JP2006137943A - Resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin compositon which has a suppressed warpage by heat and is useful as an over-coating agent on a flexible printed wiring boad. <P>SOLUTION: This resin composition contains (A) a resin having a polybutadiene structure on the molecule, (B) a thermosetting resin and (C) a compound having two or more mercapto groups in the molecule and/or a compound having two or more disulfide bonds in the molecule. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resin composition suitably used as an overcoat agent for protecting a circuit surface in a flexible printed wiring board used for TCP, COF, and the like, and further, a flexible printed wiring whose surface is protected by the resin composition The present invention relates to a board and an electronic device incorporating the wiring board.

  A flexible printed circuit board (FPC) used for TCP (Tape Carrier Package), COF (Chip On Flexible or Film), etc. is generally a conductor layer in which a circuit is formed on one or both sides of a polyester terephthalate or polyimide film. It is mainly comprised from the board | substrate which has (conductor circuit layer), and the surface protective film which protects the surface of this board | substrate. As an insulating protective film for FPC, generally, a method in which a cover lay film in which an adhesive layer is provided on a polyimide film punched into a desired shape is attached to a substrate, or a varnish-like resin composition (over A method is known in which a coating agent) is printed in a desired pattern by screen printing and cured. Since a method using a coverlay film is disadvantageous in terms of workability and cost, a method of coating an overcoat agent by screen printing is becoming mainstream.

  The resin composition used for the FPC overcoat agent is required to have a cured product with excellent flexibility and less warpage. Examples of a method for imparting such characteristics include a method using a resin having a polybutadiene skeleton. In Patent Documents 1 and 2, an overcoat agent for a flexible circuit having a polybutadiene skeleton containing a specific polybutadiene polyol, polyester polyol and polybutadiene blocked isocyanate, a polyimide resin, a resin composition containing a polybutadiene polyol and polyblock isocyanate are flexible. It is disclosed that it is excellent in properties such as property and warpage and is suitable as an overcoat agent for a flexible circuit.

  On the other hand, in recent years, there has been an increasing demand for thinner and smaller electronic devices, and miniaturization of wiring is also progressing in FPC. However, in the FPC in which the wiring has a fine pitch, the influence of the warp due to the heat of the surface protective film appears more prominently, which becomes a factor of significantly reducing the yield. Accordingly, there is a demand for a resin composition for an overcoat agent in which warpage due to heat is suppressed more than ever.

JP-A-11-71551 JP-A-11-199669

  An object of this invention is to provide the resin composition useful as an overcoat agent of a flexible printed wiring board by which the curvature by heat was suppressed.

  As a result of intensive studies to solve the above problems, the present inventors have found that (A) a resin having a polybutadiene structure in the molecule, (B) a thermosetting resin, and (C) two or more mercapto groups in the molecule. The resin composition characterized by containing a compound having a compound and / or a compound having a disulfide bond in the molecule contains a resin having a polybutadiene structure, and the cured product has excellent flexibility, and by heat The present inventors have found that the warpage is small and completed the present invention.

［式中、Ｒ１は２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示し、Ｒ３はジイソシアネート化合物のイソシアネート基を除いた残基を示す。］
で表されるウレタン構造を有する樹脂である、上記［１］記載の樹脂組成物。
［１１］成分（Ａ）の分子内にポリブタジエン構造を有する樹脂が、分子内に下式（1-a)：

［式中、Ｒ１は２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示し、Ｒ３はジイソシアネート化合物のイソシアネート基を除いた残基を示す。］
で表されるポリブタジエン構造及び式(1-b)

［式中、Ｒ２は四塩基酸二無水物の酸無水物基を除いた残基を示し、Ｒ３は前記と同意義を示す。］
で表されるポリイミド構造を有する変性ポリイミド樹脂である、上記［１］記載の樹脂組成物。
［１２］成分（Ｂ）の熱硬化性樹脂がエポキシ樹脂である、上記［１］〜［１１］のいずれかに記載の樹脂組成物。
［１３］樹脂組成物がエポキシ硬化剤をさらに含有する、上記［１２］記載の樹脂組成物。
［１４］成分（Ａ）と成分（Ｂ）の比が、質量比で１００：１〜１：１であり、樹脂組成物中の成分（Ａ）および（Ｂ）の合計の含有量が６０質量％以上である、上記［１］〜［１３］のいずれかに記載の樹脂組成物。
［１５］成分（Ａ）と成分（Ｃ）の比が、質量比で１０００：１〜１０：１である上記［１］〜［１４］のいずれかに記載の樹脂組成物。
［１６］樹脂組成物がさらに充填材を含有する上記［１］〜［１５］のいずれかに記載の樹脂組成物。
［１７］樹脂組成物中の充填材の含有量が５〜５０質量％である上記［１６］記載の樹脂組成物。
［１８］樹脂組成物がさらに有機溶剤を含有するワニス状の樹脂組成物である上記［１］〜［１７］のいずれかに記載の樹脂組成物。
［１９］樹脂組成物中の有機溶剤の含有量が２０〜６０質量％である上記［１８］記載の樹脂組成物。
［２０］フレキシブルプリント配線板の表面保護に使用される上記［１］〜［１９］のいずれかに記載の樹脂組成物。
［２１］上記［１］〜［１７］のいずれか一項に記載の樹脂組成物で表面が保護されたフレキシブルプリント配線板。
［２２］上記［１８］または［１９］記載の樹脂組成物ワニスを、フレキシブルプリント配線板の所定部分に塗布後、乾燥工程を経て得られる表面が保護されたフレキシブルプリント配線板。
［２３］上記［２１］または［２２］記載のフレキシブルプリント配線板を内蔵する電子機器。 That is, the present invention includes the following contents.
[1] (A) a resin having a polybutadiene structure in the molecule, (B) a thermosetting resin, and (C) a compound having two or more mercapto groups in the molecule and / or a compound having a disulfide bond in the molecule. A resin composition characterized by containing.
[2] The resin composition according to [1] above, wherein the resin having a polybutadiene structure in the molecule of component (A) is a resin having a polybutadiene structure and a polyurethane structure in the molecule.
[3] The resin composition according to [1] above, wherein the resin having a polybutadiene structure in the molecule of component (A) is a resin having a polybutadiene structure, a polyurethane structure and a polyimide structure in the molecule.
[4] The above-mentioned [1], wherein the resin having a polybutadiene structure in the molecule of component (A) is a modified polyimide resin obtained by reacting a bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride. The resin composition as described.
[5] Resin having a polybutadiene structure in the molecule of component (A) is a functional group equivalent of the isocyanate group of the diisocyanate compound with respect to the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene. The resin composition as described in [1] above, which is a modified polyimide resin obtained by reacting a tetrabutyric dianhydride with a polybutadiene diisocyanate composition obtained by reacting at a ratio exceeding 1.
[6] Resin having a polybutadiene structure in the molecule of component (A) is a bifunctional hydroxyl group-terminated polybutadiene and a diisocyanate compound, and a functional group equivalent of the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene and the isocyanate group of the diisocyanate compound. The modified polyimide resin obtained by reacting tetrabasic acid dianhydride with the polybutazine diisocyanate composition obtained by reacting at a ratio of 1: 1.5 to 1: 2.5, the above [1] The resin composition according to [1].
[7] Resin having a polybutadiene structure in the molecule of component (A) is a bifunctional hydroxyl group-terminated polybutadiene and a diisocyanate compound, and a functional group equivalent of the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene and the isocyanate group of the diisocyanate compound. A functional group of an isocyanate group of a diisocyanate compound as a raw material is added to a polybutazine diisocyanate composition obtained by reacting at a ratio of 1: 1.5 to 1: 2.5. Equivalent X, functional group equivalent W of hydroxyl group of bifunctional hydroxyl-terminated polybutadiene as a raw material, and functional group equivalent Y of acid anhydride group of tetrabasic acid dianhydride are Y> XW ≧ Y / 5 (W> 0, X> 0, Y> 0), which is a modified polyimide resin obtained by reacting at a ratio satisfying the relationship [1] The resin composition of the mounting.
[8] The modified polyimide resin obtained after the reaction is further modified with a new diisocyanate compound, an isocyanate functional group equivalent X of the diisocyanate compound as a raw material, and a hydroxyl group functional group of a bifunctional hydroxyl-terminated polybutadiene as a raw material. Equivalent W, functional group equivalent Y of acid anhydride of tetrabasic acid dianhydride, and isocyanate functional group equivalent Z of newly reacted diisocyanate compound are Y- (X-W)> Z ≧ 0 (W> 0, X > 0, Y> 0, Z> 0) The resin composition according to any one of the above [2] to [7], which is a modified polyimide resin obtained by reacting at a ratio satisfying the relationship.
[9] The resin composition according to any one of [2] to [6], wherein the number average molecular weight of the bifunctional hydroxyl group-terminated polybutadiene is 800 to 10,000.
[10] A resin having a polybutadiene structure in the molecule of component (A) is represented by the following formula (1-a):

[Wherein, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, and R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound. ]
The resin composition according to the above [1], which is a resin having a urethane structure represented by:
[11] A resin having a polybutadiene structure in the molecule of component (A) has the following formula (1-a):

[Wherein, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, and R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound. ]
Polybutadiene structure represented by the formula (1-b)

[Wherein R2 represents a residue obtained by removing an acid anhydride group of a tetrabasic acid dianhydride, and R3 has the same meaning as described above. ]
The resin composition according to the above [1], which is a modified polyimide resin having a polyimide structure represented by the formula:
[12] The resin composition according to any one of [1] to [11], wherein the thermosetting resin of the component (B) is an epoxy resin.
[13] The resin composition according to the above [12], wherein the resin composition further contains an epoxy curing agent.
[14] The ratio of the component (A) to the component (B) is 100: 1 to 1: 1 by mass ratio, and the total content of the components (A) and (B) in the resin composition is 60 mass. % Of the resin composition according to any one of the above [1] to [13].
[15] The resin composition according to any one of [1] to [14], wherein the ratio of the component (A) to the component (C) is 1000: 1 to 10: 1 in terms of mass ratio.
[16] The resin composition according to any one of [1] to [15], wherein the resin composition further contains a filler.
[17] The resin composition according to the above [16], wherein the content of the filler in the resin composition is 5 to 50% by mass.
[18] The resin composition according to any one of [1] to [17], wherein the resin composition is a varnish-like resin composition further containing an organic solvent.
[19] The resin composition according to the above [18], wherein the content of the organic solvent in the resin composition is 20 to 60% by mass.
[20] The resin composition according to any one of [1] to [19], which is used for protecting a surface of a flexible printed wiring board.
[21] A flexible printed wiring board whose surface is protected with the resin composition according to any one of [1] to [17].
[22] A flexible printed wiring board having a protected surface obtained through a drying step after applying the resin composition varnish of [18] or [19] to a predetermined portion of the flexible printed wiring board.
[23] An electronic device incorporating the flexible printed wiring board according to [21] or [22].

  The resin composition of the present invention is suitable as an overcoat agent for flexible printed wiring boards because the cured product has excellent flexibility by containing a resin having a polybutadiene structure in the molecule, and warpage due to heat is small. Can be used.

The resin composition of the present invention mainly contains a resin having a polybutadiene structure in the molecule, a thermosetting resin, a compound having two or more mercapto groups in the molecule, and / or a compound having a disulfide bond in the molecule. Features.
That is, the present invention provides a resin composition comprising a resin having a polybutadiene structure and a thermosetting resin that imparts an excellent flexibility effect in a cured product, and / or a compound having two or more mercapto groups in the molecule and / or in the molecule. By blending disulfide bonds, a resin composition can be obtained in which the warpage that occurs when the resin composition is cured in layers is significantly reduced. In addition to flexibility due to the inclusion of a resin having a polybutadiene structure in the molecule, the warpage during curing is reduced, so it is useful as a resin composition for flexible printed wiring boards, especially the surface of flexible printed wiring boards. It is suitable as a protective resin composition (overcoat agent for flexible printed wiring boards).

  The “resin having a polybutadiene structure in the molecule” of the component (A) in the present invention is not particularly limited, but is usually a copolymer of polybutadiene and another compound, preferably from the viewpoint of flexibility, a polybutadiene structure in the molecule. And resins having a polyurethane structure.

  Examples of the resin having a polybutadiene structure and a polyurethane structure in the molecule include a resin having a repeating unit represented by the following formula (1-a) in the molecule.

［式中、Ｒ１は２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示し、Ｒ３はジイソシアネート化合物のイソシアネート基を除いた残基を示す。］

[Wherein, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, and R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound. ]

  In the resin composition of the present invention, the component (A) “resin having a polybutadiene structure in the molecule” is used in a flexible printed wiring board, and particularly has a polybutadiene structure and a polyurethane structure in the molecule from the viewpoint of heat resistance. In addition, a resin having a polyimide structure is preferable.

  Examples of the resin having a polybutadiene structure, a polyurethane structure, and a polyimide structure in the molecule include modified polyimide resins having a repeating unit represented by the following formulas (1-a) and (1-b) in the molecule.

「式中、Ｒ１は２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示し、Ｒ２は四塩基酸二無水物の酸無水物基を除いた残基を示し、Ｒ３はジイソシアネート化合物のイソシアネート基を除いた残基を示す。」

"In the formula, R1 represents a residue obtained by removing the hydroxyl group of the polyfunctional hydroxyl group-terminated polybutadiene, R2 represents a residue obtained by removing the acid anhydride group of tetrabasic acid dianhydride, and R3 represents a diisocyanate compound. The residue excluding the isocyanate group is shown. "

The modified polyimide resin particularly preferred in the present invention is:
[A] a bifunctional hydroxyl group-terminated polybutadiene,
It can be obtained by reacting three components of [b] diisocyanate compound and [c] tetrabasic dianhydride.

  As the bifunctional hydroxyl group-terminated polybutadiene, a bifunctional hydroxyl group-terminated polybutadiene having a number average molecular weight of 800 to 10,000 is preferable. Moreover, as a polybutadiene structure of a formula (1-a), the case where R1 in a formula shows the residue remove | excluding the hydroxyl group of the bifunctional hydroxyl group terminal polybutadiene whose number average molecular weight is 800-10000 is preferable. When the number average molecular weight of the bifunctional hydroxyl group-terminated polybutadiene is 800 or less, the modified polyimide resin tends to lack flexibility, and when it is 10,000 or more, the modification polyimide resin tends to lack compatibility with the thermosetting resin. There is also a tendency to lack heat resistance. In the present invention, the number average molecular weight is a value measured by gel permeation chromatography (GPC) method (polystyrene conversion). Specifically, the number average molecular weight by the GPC method is LC-9A / RID-6A manufactured by Shimadzu Corporation as a measuring device, and Shodex K-800P / K-804L / K manufactured by Showa Denko KK as a column. -804L can be measured using chloroform as a mobile phase at a column temperature of 40 ° C. and calculated using a standard polystyrene calibration curve.

  In the modified polyimide resin, the number of polybutadiene structures (1-a) per molecule is usually 1 to 10,000, preferably 1 to 100, and the number of polyimide structures (1-b) is usually 1. ~ 100, preferably 1-10.

  The number average molecular weight of the modified polyimide resin is not particularly limited, but is usually 5,000 to 200,000, preferably 10,000 to 100,000.

各式中の記号は前記と同義である。 Moreover, each component [a]-[c] used as the raw material of a modified polyimide resin composition can be represented by the following formulas (a)-(c) in order.

The symbols in each formula are as defined above.

  In order to efficiently obtain the modified polyimide resin composition in the present invention, the following procedure is preferably used.

First, the polybutadiene of component [a] and the diisocyanate compound of component [b] are reacted at a ratio of the functional group equivalent of the isocyanate group of the diisocyanate compound to the hydroxyl group of the polybutadiene exceeding 1, thereby obtaining a composition containing polybutadiene diisocyanate. The polybutadiene diisocyanate can be represented by the following formula (ab).

  In the formula, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound, and n is 1 or more and 100 or less (0 ≦ n ≦ 100). ). n preferably represents an integer of 1 or more and 10 or less (0 ≦ n ≦ 10). In the formula, R1 represents a residue obtained by removing a hydroxyl group of a difunctional hydroxyl group-terminated polybutadiene, R2 represents a residue obtained by removing an acid anhydride group of a tetrabasic acid dianhydride, and R3 represents an isocyanate of a diisocyanate compound. The residue without a group is shown. In the polybutadiene isocyanate represented by the formula (a-b), it is preferable that R1 in the formula represents a residue excluding the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene having a molecular weight of 800 to 10,000.

  The reaction ratio of the polybutadiene and the diisocyanate compound is preferably such that the functional group equivalent ratio of the isocyanate group of the diisocyanate compound to the hydroxyl group of the polybutadiene is 1: 1.5 to 1: 2.5.

  Next, tetrabasic acid dianhydride is reacted with the polybutadiene diisocyanate composition. The reaction ratio of the tetrabasic acid dianhydride is not particularly limited, but it is preferable not to leave the isocyanate group in the composition as much as possible. The functional group equivalent of the isocyanate group of the diisocyanate compound that is the raw material is X, and the raw material is When the functional group equivalent of the hydroxyl group of the bifunctional hydroxyl-terminated polybutadiene is W and the functional group equivalent of the acid anhydride group of the tetrabasic acid dianhydride is Y, Y> X−W ≧ Y / 5 (W> 0, X > 0, Y> 0) It is preferable to react at a ratio satisfying the relationship.

式中、Ｒ１は２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示し、Ｒ２は四塩基酸二無水物の酸無水物基を除いた残基を示し、Ｒ３はジイソシアネート化合物のイソシアネート基を除いた残基を示し、ｎ及びｍは１以上１００以下（１≦ｎ≦１００）の整数を示す。ｎ及びｍは好ましくは１以上１０以下（１≦ｎ≦１０）の整数を示す。式（a-b-c）におけるポリブタジエン構造としては、式中のＲ１が、８００〜１００００の２官能性ヒドロキシル基末端ポリブタジエンのヒドロキシル基を除いた残基を示す場合が好ましい。 As described above, the modified polyimide resin thus obtained contains both the polybutadiene structure represented by the formula (1-a) and the imide structure represented by the formula (1-b) in the molecule. It is a waste. In addition, the modified polyimide resin composition in the present invention preferably has a modified polyimide containing a structure represented by the following formula (abc) as a main component.

In the formula, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, R2 represents a residue obtained by removing the acid anhydride group of a tetrabasic acid dianhydride, and R3 represents an isocyanate of a diisocyanate compound. The residue except a group is shown, n and m show the integer of 1-100 (1 <= n <= 100). n and m are preferably integers of 1 or more and 10 or less (1 ≦ n ≦ 10). As the polybutadiene structure in the formula (abc), it is preferable that R1 in the formula represents a residue excluding the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene of 800 to 10,000.

各式中の記号は前記と同義である。 In order not to leave the isocyanate group in the polybutadiene diisocyanate composition as much as possible, it is preferable to confirm the disappearance of the isocyanate group by FT-IR or the like during the reaction. The terminal group of the modified polyimide resin thus obtained can be represented by the following formula (1-c) or the following formula (1-d).

The symbols in each formula are as defined above.

  In the production of the modified polyimide resin, a polybutadiene diisocyanate composition and tetrabasic dianhydride are reacted, and then further reacted with a diisocyanate compound, whereby a higher molecular weight modified polyimide resin can be obtained. The reaction ratio of the isocyanate compound in this case is not particularly limited, but the isocyanate functional group equivalent of the isocyanate compound as the raw material is X, the hydroxyl group functional group equivalent of the bifunctional hydroxyl-terminated polybutadiene as the raw material is W, tetrabasic acid dianhydride Y- (X-W)> Z ≧ 0 (W> 0, X> 0, Y> 0) where Y is the functional group equivalent of the acid anhydride and Z is the isocyanate functional group equivalent of the isocyanate compound to be newly reacted. , Z> 0) is preferably reacted at a ratio satisfying the relationship.

  The modified polyimide resin in the present invention includes two chemical structural units of a polybutadiene structure represented by the above formula (1-a) and a polyimide structure represented by the above formula (1-b). Usually, in order to impart flexibility to the resin composition, it is common to directly mix a rubber-based resin such as polybutadiene resin into the resin composition, but nonpolar rubber-based resins are highly polar. Phase separation is likely to occur in the thermosetting resin composition, and it is difficult to obtain a stable composition particularly when the content of the rubber-based resin is high. In addition, a resin composition containing a rubber-based resin often cannot obtain sufficient heat resistance. On the other hand, the polyimide resin has heat resistance and has a relatively high compatibility with the thermosetting resin composition because of its high polarity. Since the modified polyimide resin of the present invention has both the polyimide structure and the polybutadiene structure imparting flexibility in one molecule, it becomes a material excellent in both flexibility and heat resistance, and further is a thermosetting resin. Therefore, it is a material suitable for obtaining a stable thermosetting resin composition.

  The composition ratio of the polybutadiene structure and the polyimide structure in the modified polyimide resin in the present invention can be changed by adjusting the reaction ratio of the raw materials. When the proportion of the polybutadiene structure is large, the resin composition of the present invention is a material with more flexibility, and when the proportion of the polyimide structure is large, the resin composition is a material with more excellent heat resistance. Further, it is known that a compound having a polybutadiene structure or a polyimide structure tends to exhibit low values of dielectric constant and dielectric loss tangent, and the modified polyimide resin in the present invention has both skeletons, so that the resin composition of the present invention Is an insulating material with excellent dielectric properties. In particular, when the proportion of the polybutadiene structure in the modified polyimide resin is large, the material is more excellent in dielectric characteristics.

  Component [a] Bifunctional hydroxyl group-terminated polybutadiene in the raw material of the modified polyimide resin in the present invention means that both ends of the polybutadiene are hydroxyl groups. The polybutadiene may be one in which a part of the unsaturated bond in the molecule is hydrogenated. Specific examples of the bifunctional hydroxyl group-terminated polybutadiene include, for example, G-1000, G-3000, GI-1000, GI-3000 (manufactured by Nippon Soda Co., Ltd.), R-45EPI (Idemitsu Kosan Co., Ltd.) )).

  Examples of the component [b] diisocyanate compound used as a raw material for the modified polyimide resin in the present invention include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and the like. And diisocyanate.

  Specific examples of the component [c] tetrabasic acid dianhydride used as a raw material for the modified polyimide resin in the present invention include pyromellitic acid dianhydride, benzophenone tetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride. , Naphthalenetetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-cyclohexene-1,2-dicarboxylic anhydride, 3,3′-4,4′-diphenylsulfonetetra Carboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3- Examples include dione.

  In the production of the modified polyimide resin in the present invention, the reaction between the bifunctional hydroxyl group-terminated polybutadiene and the diisocyanate compound can be carried out in an organic solvent under a reaction temperature of 80 ° C. or lower and a reaction time of usually 1 to 8 hours. . Moreover, you may carry out in catalyst presence if needed. The reaction of the polybutadiene diisocyanate composition and the tetrabasic acid dianhydride is carried out by cooling the solution containing the polybutadiene diisocyanate composition obtained after the above reaction to room temperature, and then adding the tetrabasic acid dianhydride thereto, and the reaction temperature of 120 to The reaction can be carried out under conditions of 180 ° C. and reaction time of 2 to 24 hours. The reaction is usually performed in the presence of a catalyst. Moreover, you may carry out by adding an organic solvent further. The obtained reaction solution may be filtered in order to remove insoluble matters as necessary. The resulting reaction solution may be purified by adding a solvent that is a poor solvent for the modified polyimide, and separating the modified polyimide, but usually such purification is not necessary, If necessary, it can be used as it is as the modified imide resin varnish in the present invention by filtering to remove insoluble matters.

  In the varnish-like modified polyimide resin thus obtained, the amount of the solvent in the varnish can be appropriately adjusted by adjusting the amount of the solvent during the reaction or adding a solvent after the reaction. Further, after the reaction of the polybutadiene diisocyanate composition and the tetrabasic acid dianhydride, a diisocyanate can be further reacted to obtain a modified polyimide resin having a higher molecular weight. In this case, the diisocyanate compound is added dropwise to the reaction product of the polybutadiene diisocyanate composition and the tetrabasic dianhydride, and the reaction can be carried out under conditions of a reaction temperature of 120 to 180 ° C. and a reaction time of 2 to 24 hours.

  Examples of the organic solvent used in the above reactions include N, N′-dimethylformamide, N, N′-diethylformamide, N, N′-dimethylacetamide, N, N′-diethylacetamide, dimethylsulfoxide, diethyl Examples include polar solvents such as sulfoxide, N-methyl-2-pyrrolidone, tetramethylurea, γ-butyrolactone, cyclohexanone, diglyme, triglyme, carbitol acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate. These solvents may be used as a mixture of two or more. Further, if necessary, a nonpolar solvent such as an aromatic hydrocarbon can be appropriately mixed and used.

  Examples of the catalyst used in each of the above reactions include tetotamethylbutanediamine, benzyldimethylamine, triethanolamine, triethylamine, N, N′-dimethylpiperidine, α-methylbenzyldimethylamine, N-methylmorpholine, triethylene. Tertiary amines such as diemine and organometallic catalysts such as dibutyltin laurate, dimethyltin dichloride, cobalt naphthenate and zinc naphthenate can be used. These catalysts may be used in combination of two or more. In particular, it is most preferable to use triethylenediamine as the catalyst.

  As the “thermosetting resin” of the component (B) in the present invention, for example, an epoxy resin, a urethane resin comprising a mixture of isocyanate and polyol or a mixture of blocked isocyanate and polyol, a bismaleimide resin, a cyanate ester resin, a bisallyl azide resin, Examples thereof include vinyl benzyl ether resin, benzoxazine resin, and polymer of bismaleimide and diamine. These thermosetting resins may be used in combination of two or more. As the thermosetting resin in the present invention, an epoxy resin is particularly preferable.

  Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac epoxy resin, bisphenol S type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type. Examples of epoxy resins having two or more functional groups in one molecule such as epoxy resins, epoxidized products of condensation products of phenol and aromatic aldehydes having phenolic hydroxyl groups, triglycidyl isocyanurate, alicyclic epoxy resins, etc. be able to. Two or more of these epoxy resins may be mixed and used.

  When using an epoxy resin, an epoxy curing agent is usually required. As an epoxy curing agent, for example, an amine curing agent, a guanidine curing agent, an imidazole curing agent, a phenol curing agent, an acid anhydride curing agent, a thiol curing agent, or an epoxy adduct or microencapsulation thereof. The thing etc. can be mentioned. In particular, an imidazole curing agent is preferable from the viewpoint of viscosity stability when the resin composition is used as a printing ink. Two or more epoxy curing agents may be mixed and used. Further, a curing accelerator such as triphenylphosphine, phosphonium borate, 3- (3,4-dichlorophenyl) -1,1-dimethylurea may be used in combination.

  Specific examples of the epoxy curing agent include, for example, dicyandiamide as an amine curing agent, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4-diamino-6- [2′-methyl as an imidazole curing agent, and the like. Examples include imidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct.

  When using the resin composition of this invention as an overcoat agent of a flexible printed wiring board, the ratio of a component (A) and a component (B) is 100: 1 by mass ratio in the thermosetting resin of a component (B). It is preferable to use in the range of 1: 1. If the ratio of the resin of component (A) is larger than this, the degree of crosslinking tends to decrease and the chemical resistance tends to decrease, and if it is less than this, the degree of crosslinking becomes too high and it is difficult to obtain sufficient flexibility. It is in. Moreover, it is preferable that content of the sum total of a component (A) and (B) is 60 mass% or more in the resin composition (100 mass%) of this invention. Here, the total content of components (A) and (B) is calculated as the content in the resin composition component excluding the organic solvent when the resin composition such as the resin composition varnish contains the organic solvent. When the amount is less than 60% by mass, the function as an overcoat agent may not be sufficiently obtained in the resin composition.

  As the “compound having two or more mercapto groups in the molecule and / or the compound having a disulfide bond in the molecule” of the component (C) in the present invention, 1,4-butanedithiol, p-xylene-α, α ′ -Dithiol, 2,4,6-trimercapto-s-triazole, 2,5-dimercapto-1,3,4-thiadiazole and other dithiol compounds having two or more mercapto groups in one molecule, diethyl disulfide, diphenyl A compound having a disulfide bond in one molecule such as disulfide, dihexyl disulfide, and dioctyl disulfide can be used. Preferable examples include 2,4,6-trimercapto-s-triazole and 2,5-dimercapto-1,3,4-thiadiazole.

  The component (C) is preferably used in a range where the ratio of the component (A) to the component (C) is 1000: 1 to 10: 1 by mass ratio, and more preferably in the range of 200: 1 to 20: 1. More preferably it is used. When the ratio of the component (C) is smaller than this, the effect of reducing the warp tends not to be sufficiently obtained. On the other hand, if it is larger than this, the problem of odor tends to occur, and when the overcoat agent is stored, the pot life tends to be shortened due to increase in viscosity.

  The resin composition of the present invention may further contain a filler. The filler may be either an organic filler or an inorganic filler. Two or more fillers can be mixed and used. By using an inorganic filler, the mechanical strength of the coating film can be improved. Although the compounding quantity of an inorganic filler is not specifically limited, Preferably, it can add in 5-50 mass% or less in this resin composition. If it exceeds 50% by mass, it tends to be difficult to apply the resin composition varnish to the surface of the flexible circuit board, and the elastic modulus of the formed surface protective film tends to increase and the toughness tends to decrease. If it is less than 5% by mass, the effect of improving the mechanical strength tends not to be sufficiently exhibited.

  Inorganic fillers include silica, alumina, barium sulfate, talc, clay, mica powder, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum borate, barium titanate, titanate Examples include strontium, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, barium zirconate, and calcium zirconate. Silica and talc are particularly preferable. The inorganic filler preferably has an average particle size of 5 μm or less. Examples of the organic filler include acrylic rubber particles, polyamide fine particles, and silicone particles. Specific examples of the acrylic rubber particles are fine particles of a resin that has been subjected to a chemical crosslinking treatment on a resin exhibiting rubber elasticity such as acrylonitrile butadiene rubber, butadiene rubber, and acrylic rubber, and is insoluble and infusible in an organic solvent. Any of these may be used, for example, XER-91 (manufactured by Nippon Synthetic Rubber Co., Ltd.), Staphyloid AC3355, AC3816, AC3832, AC4030, AC3364, IM101 (above, Gantz Kasei Co., Ltd.) EXL2655, EXL2602 (above, manufactured by Kureha Chemical Industry Co., Ltd.) and the like. Specific examples of the polyamide fine particles include aliphatic polyamides such as nylon, aromatic polyamides such as Kevlar, and polyamide imide and other resins having an amide bond of 50 microns or less. For example, VESTOSINT 2070 (manufactured by Daicel Huls Co., Ltd.) or SP500 (manufactured by Toray Industries, Inc.) can be used. The organic filler preferably has an average particle size of 5 μm or less. The average particle diameter can be measured with a laser diffraction / scattering particle size distribution analyzer LA-500 manufactured by Horiba, Ltd.

  In the resin composition of the present invention, various resin additives, resin components other than the components (A) and (B), and the like can be blended as long as the effects of the present invention are exhibited. Examples of resin additives include, for example, coupling agents such as silane coupling agents, titanate coupling agents, aluminum coupling agents, silicone defoaming agents, fluorine defoaming agents, and acrylic polymer deodorizing agents. Antifoaming agents such as foaming agents, thickeners such as Orben and Benton, coloring agents such as phthalocyanine blue, phthalocyanine green, iodin green, disazo yellow, carbon black, phosphorus containing compounds, bromine containing compounds, aluminum hydroxide And flame retardants such as magnesium hydroxide, leveling agents, thixotropic agents and the like. Examples of other resin components include polyester polyol resin, polyimide resin, and polyamideimide resin.

  When the resin composition of the present invention is used for surface protection of a flexible printed wiring board, that is, when used as an overcoat agent for a flexible printed wiring board, an organic solvent is usually added to the resin composition. Used in the form of varnish. Examples of the organic solvent used for preparing the varnish-like resin composition, that is, the resin composition varnish, include, for example, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, Examples thereof include acetates such as carbitol acetate, carbitols such as cellosolve and butyl carbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These organic solvents may be used in combination of two or more. The resin composition varnish of the present invention further includes an organic solvent in the resin composition of the present invention, and is conceptually included in the resin composition of the present invention. The content of the organic solvent in the varnish-like resin composition varies depending on the molecular structure of the resin, solubility in the organic solvent, molecular weight, etc., but is preferably 20 to 60% by mass, and more preferably 30 to 50% by mass. % Is more preferable.

  By applying the resin composition varnish of the present invention to a predetermined portion of a flexible printed wiring board and drying the coated surface, a flexible printed wiring board having the entire surface or a part of the surface protected by the resin composition of the present invention is obtained. Obtainable. The drying conditions can be set as appropriate by those skilled in the art depending on the type of resin composition varnish to be used, but are usually dried at 100 to 200 ° C. for about 1 to 120 minutes. The thickness of the surface protective film to be formed is not particularly limited, but is usually 5 to 100 μm. The flexible printed wiring board whose surface is protected by the resin composition of the present invention is not particularly limited, and is a TAB flexible printed wiring board, a COF flexible printed wiring board, a multilayer flexible printed wiring board, a conductive paste printed flexible printed wiring board. However, it can be suitably used particularly for TAB flexible printed wiring boards and COF flexible printed wiring boards.

  The flexible printed wiring board whose surface is protected by the resin composition of the present invention is used in a form incorporated in various electronic devices. For example, mobile phones, digital cameras, video cameras, game machines, personal computers, printers, hard disk drives, plasma TVs, liquid crystal TVs, liquid crystal displays, car navigation systems, copiers, fax machines, AV equipment, measuring equipment, medical equipment It is suitably used as internal wiring of various electronic devices such as.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated concretely, this invention is not limited to this. In addition, in an Example, a part means a mass part.

<Manufacture of modified polyimide resin varnish A>
In a reaction vessel, 50 g of G-3000 (bifunctional hydroxyl group-terminated polybutadiene, number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1798 g / eq., Solid content: 100 mass%: Nippon Soda Co., Ltd.) 23.5 g of ipsol 150 (aromatic hydrocarbon-based mixed solvent: manufactured by Idemitsu Kosan Co., Ltd.) and 0.005 g of dibutyltin laurate were mixed and dissolved uniformly. When the temperature became uniform, the temperature was raised to 50 ° C., and while further stirring, 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) Was added and the reaction was carried out for about 3 hours. The reaction was then cooled to room temperature before 8.96 g benzophenonetetracarboxylic dianhydride (acid anhydride equivalent = 161.1 g / eq.), 0.07 g triethylenediamine, and ethyl diglycol. 40.4 g of acetate (manufactured by Daicel Chemical Industries, Ltd.) was added, the temperature was raised to 130 ° C. with stirring, and the reaction was carried out for about 4 hours. The disappearance of the NCO peak at 2250 cm ⁻¹ was confirmed by FT-IR. Confirming the disappearance of the NCO peak was regarded as the end point of the reaction, and the reaction product was cooled to room temperature and then filtered through a 100 mesh filter cloth to obtain a modified polyimide resin varnish A.

Properties of modified polyimide resin varnish A: Viscosity = 7.5 Pa · s (25 ° C., E-type viscometer)
Acid value = 16.9 mgKOH / g
Solid content (components other than solvent) = 50 mass%
Number average molecular weight = 13723
Polybutadiene structure content = 50 * 100 / (50 + 4.8 + 8.96)
= 78.4% by mass

<Manufacture of modified polyimide resin varnish B>
In a reaction vessel, 50 g of G-3000 (bifunctional hydroxyl group-terminated polybutadiene, number average molecular weight = 5047 (GPC method), hydroxyl group equivalent = 1798 g / eq., Solid content: 100 mass%: Nippon Soda Co., Ltd.) 23.5 g of ipsol 150 (aromatic hydrocarbon-based mixed solvent: manufactured by Idemitsu Kosan Co., Ltd.) and 0.007 g of dibutyltin laurate were mixed and dissolved uniformly. When the temperature became uniform, the temperature was raised to 50 ° C., and while further stirring, 4.8 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) Was added and the reaction was carried out for about 3 hours. The reaction was then allowed to cool to room temperature, after which 8.83 g of benzophenone tetracarboxylic dianhydride (acid anhydride equivalent = 161.1 g / eq.), 0.07 g of triethylenediamine, ethyl diglycol 74.09 g of acetate (manufactured by Daicel Chemical Industries, Ltd.) was added, the temperature was raised to 130 ° C. with stirring, and the reaction was performed for about 4 hours. When the disappearance of the NCO peak at 2250 cm ⁻¹ was confirmed by FT-IR, 1.42 g of toluene-2,4-diisocyanate (isocyanate group equivalent = 87.08 g / eq.) Was added, and again at 130 ° C. While stirring for 2 to 6 hours, the disappearance of the NCO peak was confirmed by FT-IR. Confirming the disappearance of the NCO peak was regarded as the end point of the reaction, and the temperature was lowered to room temperature, followed by filtration with a 100 mesh filter cloth to obtain a modified polyimide resin varnish B.

Properties of modified polyimide resin varnish B: Viscosity = 7.0 Pa · s (25 ° C., E-type viscometer)
Acid value = 6.9 mgKOH / g
Solid content = 40% by mass
Number average molecular weight = 19890
Content ratio of polybutadiene structure = 50 * 100 / (50 + 4.8 + 8.83 + 1.43)
= 76.9% by mass

<Other resin varnish properties>
(i) Polybutadiene polyol (G-1000, manufactured by Nippon Soda Co., Ltd., OH-terminated polybutadiene, solid content: 100% by mass)
(ii) Cresol novolac type epoxy resin varnish (N695, Dainippon Ink Co., Ltd., carbitol acetate solution, solid content 80% by mass)
(iii) Dicyclopentadiene type epoxy resin varnish (HP 7200, Dainippon Ink Co., Ltd., carbitol acetate solution, solid content 80% by mass)
(iv) Polyester polyol (Byron-200, Toyobo Co., Ltd., OH-terminated polyester polyol, carbitol acetate / petroleum naphtha = 2/1 solid content 45% by mass)

<Manufacture of polybutadiene polyblock isocyanate resin varnish>
In a reaction vessel, 1000 g of HTP-9 (manufactured by Idemitsu Kosan Co., Ltd., NCO-terminated polybutadiene, NCO equivalent = 467 g / eq., Solid content = 100% by mass), 216 g of carbitol acetate, and 0.1 g of dibutyltin dilaurate were mixed uniformly. Dissolved in. When the temperature became uniform, the temperature was raised to 70 ° C., and 214 g of methylethylethone oxime was added dropwise over 2 hours with further stirring, and held for 1 hour, and the absorption peak of NCO at 2250 cm ⁻¹ was confirmed to disappear by FT-IR. The temperature was then lowered to obtain a polybutadiene polyblock isocyanate resin varnish resin varnish.

Properties of polybutadiene polyblock isocyanate resin varnish resin varnish:
NCO equivalent = 672.5 g / eq, solid content 85 mass%

<Evaluation method of surface protective film>
1. Warpage test: on a polyimide film having a length of 35 mm × width 60 mm × thickness 40 μm, a thickness of 15 μm was applied within a range of 25 mm × 35 mm, and the amount of warpage after curing was measured under the following conditions. The amount of warpage was measured by measuring the height (mm) of the warp on the surface plate with the coating surface down.
Conditions: Aged specimens cured at 120 ° C./90 minutes at 150 ° C. for 100 hours.
Judgment standard ◎: Warpage amount is 0.2 mm or less ○: Warpage amount is 1.0 mm or less ×: Warpage amount exceeds 1.0 mm

2. Bending resistance (flexibility) test: A test piece coated on a polyimide film having a length of 35 mm × width 60 mm × thickness 40 μm within a range of 25 mm × 35 mm with a thickness of 15 μm and cured at 120 ° C. for 90 minutes is bent 180 °. The surface of the coating film was observed.
○: No change in coating film before and after bending.
(Triangle | delta): A change is seen in a part of coating film before and behind bending.
X: A change is seen in the coating film before and after bending.

3. Heat resistance: ILB (Inner Lead Bonding) simulated heat resistance test: A resin composition is applied at a thickness of 15 μm on a polyimide substrate on which a 40 μm pitch copper wiring pattern is formed, and cured at 120 ° C. for 90 minutes to prepare a test piece did. A heating tool of an ILB bonder was brought into contact with the boundary portion between the application portion and non-application portion of the resin composition in the pattern portion for 2 seconds, and the presence or absence of occurrence of swelling in the resin composition was observed. If no blistering occurred, the temperature of the heating tool was raised by 10 ° C., and the same operation was repeated. The limit temperature at which no blistering was observed was defined as the heat resistant temperature.

4). Chemical resistance: A test piece coated on a polyimide film with a length of 35 mm x width 60 mm x thickness 40 μm within a range of 25 mm x 35 mm with a thickness of 15 μm and cured at 120 ° C. for 90 minutes is immersed in 1M hydrochloric acid for 30 minutes. The appearance of the coating film was observed.
○: No change in coating film before and after immersion.
(Triangle | delta): A change is seen in a part of coating film before and behind immersion.
X: A change is seen in the coating film before and after immersion.

5. Solvent resistance: A coating of a test piece which was coated on a polyimide film having a length of 35 mm × width 60 mm × thickness 40 μm within a range of 25 mm × 35 mm with a thickness of 15 μm and cured for 90 minutes at 120 ° C. was soaked with acetone. The coating was rubbed with a waste cloth and the appearance of the coating was observed.
○: No change in coating film before and after rubbing.
(Triangle | delta): A change is seen in a part of coating film before and after rubbing.
X: Change is seen in the coating film before and after rubbing.

6). Electrical insulation: A test piece obtained by applying a resin composition with a thickness of 15 μm on a polyimide substrate having a comb copper wiring pattern with a pitch of 30 μm and curing for 90 minutes at 120 ° C., 25 ± 3 ° C., 50 ± 10% RH The insulation resistance value (initial value) was measured after standing for 2 hours or more in the environment. Insulation resistance after placing the test piece in a constant temperature and humidity chamber of 85 ± 2 ° C and 85 ± 2% RH, applying 60V, and leaving it in an environment of 25 ± 3 ° C and 50 ± 10% RH for 2 hours The value was measured.

  Each component of (A) to (E) was blended according to Example 1 in Table 1, kneaded using three rolls, and then a viscosity of 20 ± 2 Pa · S using carbitol acetate and petroleum naphtha as viscosity adjusting solvents. Adjusted. It apply | coated to each evaluation base material with a predetermined film thickness, and it dried and hardened on the conditions of 120 degreeC / 90 minutes, and created the test sample.

  Each component was blended according to Example 2 in Table 1, and a test sample was prepared in the same manner as in Example 1.

  Each component was blended according to Example 3 in Table 1, and a test sample was prepared in the same manner as in Example 1.

  Each component was blended according to Example 4 in Table 1, and a test sample was prepared in the same manner as in Example 1.

  Each component was blended according to Example 5 in Table 1, kneaded using three rolls, added with component (G), stirred with a planetary mixer, and then carbitol acetate and petroleum naphtha were used as viscosity adjusting solvents. The viscosity was adjusted to 20 ± 2 Pa · S. A test sample was prepared in the same manner as in Example 1.

Each component was mix | blended according to Example 6 of Table 1, and the test sample was created by the method similar to an Example.

*) The numerical values in the table represent parts by mass including the solvent in the raw material.
*) In the table, Aerosil A-200: Ultrafine silica, manufactured by Nippon Aerosil Co., Ltd.

<Comparative Examples 1-3>
Each component was blended according to Comparative Examples 1 to 3 in Table 1, and test samples were prepared in the same manner as in Example 1.

About Examples 1-6 and Comparative Examples 1-3, evaluation of each item was implemented and the result was put together in Table 2.

  It turns out that the resin composition of Examples 1-6 is excellent in the softness | flexibility and the curvature at the time of hardening compared with the resin composition of a comparative example, and also excellent in chemical resistance, heat resistance, and electrical insulation.

Claims (23)

(A) A resin having a polybutadiene structure in the molecule, (B) a thermosetting resin, and (C) a compound having two or more mercapto groups in the molecule and / or a compound having a disulfide bond in the molecule. A resin composition characterized by the above. The resin composition according to claim 1, wherein the resin having a polybutadiene structure in the molecule of component (A) is a resin having a polybutadiene structure and a polyurethane structure in the molecule. The resin composition according to claim 1, wherein the resin having a polybutadiene structure in the molecule of component (A) is a resin having a polybutadiene structure, a polyurethane structure, and a polyimide structure in the molecule. The resin composition according to claim 1, wherein the resin having a polybutadiene structure in the molecule of component (A) is a modified polyimide resin obtained by reacting a bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound and a tetrabasic acid anhydride. object. Resin having a polybutadiene structure in the molecule of component (A) is a bifunctional hydroxyl group-terminated polybutadiene and a diisocyanate compound, and the functional group equivalent ratio of the isocyanate group of the diisocyanate compound to the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene is 1. The resin composition according to claim 1, which is a modified polyimide resin obtained by reacting tetrabasic acid dianhydride with a polybutazine diisocyanate composition obtained by reacting at a ratio exceeding 1. The resin having a polybutadiene structure in the molecule of component (A) is a bifunctional hydroxyl group-terminated polybutadiene and diisocyanate compound, and the functional group equivalent ratio of the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene and the isocyanate group of the diisocyanate compound is 1. 2. A modified polyimide resin obtained by reacting tetrabasic acid dianhydride with a polybutazine diisocyanate composition obtained by reacting at a ratio of 1.5 to 1: 2.5. Resin composition. The resin having a polybutadiene structure in the molecule of component (A) is a bifunctional hydroxyl group-terminated polybutadiene and diisocyanate compound, and the functional group equivalent ratio of the hydroxyl group of the bifunctional hydroxyl group-terminated polybutadiene and the isocyanate group of the diisocyanate compound is 1. : Polybutazineene diisocyanate composition obtained by reacting at a ratio of 1.5 to 1: 2.5, tetrabasic acid dianhydride, functional group equivalent X of the isocyanate group of the diisocyanate compound as a raw material, The functional group equivalent W of the hydroxyl group of the bifunctional hydroxyl-terminated polybutadiene as the raw material and the functional group equivalent Y of the acid anhydride group of the tetrabasic acid dianhydride are Y> XW ≧ Y / 5 (W> 0, X The tree according to claim 1, which is a modified polyimide resin obtained by reacting at a ratio satisfying the relationship of> 0, Y> 0). Composition. The modified polyimide resin obtained after the reaction is further modified with a new diisocyanate compound, the isocyanate functional group equivalent X of the diisocyanate compound as the raw material, the hydroxyl functional group equivalent W of the bifunctional hydroxyl-terminated polybutadiene as the raw material, The functional group equivalent Y of the acid anhydride of the tetrabasic dianhydride and the isocyanate functional equivalent Z of the diisocyanate compound to be newly reacted are Y- (XW)> Z ≧ 0 (W> 0, X> 0, The resin composition according to any one of claims 4 to 7, which is a modified polyimide resin obtained by reacting at a ratio satisfying a relationship of Y> 0, Z> 0). The resin composition as described in any one of Claims 4-6 whose number average molecular weights of bifunctional hydroxyl group terminal polybutadiene are 800-10000. A resin having a polybutadiene structure in the molecule of component (A) is represented by the following formula (1-a):

[Wherein, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, and R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound. ]
The resin composition of Claim 1 which is resin which has the urethane structure represented by these. A resin having a polybutadiene structure in the molecule of component (A) is represented by the following formula (1-a):

[Wherein, R1 represents a residue obtained by removing the hydroxyl group of the difunctional hydroxyl group-terminated polybutadiene, and R3 represents a residue obtained by removing the isocyanate group of the diisocyanate compound. ]
Polybutadiene structure represented by the formula (1-b)

[Wherein R2 represents a residue obtained by removing an acid anhydride group of a tetrabasic acid dianhydride, and R3 has the same meaning as described above. ]
The resin composition according to claim 1, which is a modified polyimide resin having a polyimide structure represented by: The resin composition as described in any one of Claims 1-11 whose thermosetting resin of a component (B) is an epoxy resin. The resin composition according to claim 12, wherein the resin composition further contains an epoxy curing agent. The ratio of the component (A) to the component (B) is 100: 1 to 1: 1 by mass ratio, and the total content of the components (A) and (B) in the resin composition is 60% by mass or more. The resin composition as described in any one of Claims 1-13 which exists. The ratio of a component (A) and a component (C) is 1000: 1-10: 1 by mass ratio, The resin composition as described in any one of Claims 1-14. The resin composition according to any one of claims 1 to 15, wherein the resin composition further contains a filler. The resin composition according to claim 16, wherein the content of the filler in the resin composition is 5 to 50% by mass. The resin composition according to any one of claims 1 to 17, wherein the resin composition is a varnish-like resin composition further containing an organic solvent. The resin composition according to claim 18, wherein the content of the organic solvent in the resin composition is 20 to 60% by mass. The resin composition as described in any one of Claims 1-19 used for the surface protection of a flexible printed wiring board. The flexible printed wiring board by which the surface was protected with the resin composition as described in any one of Claims 1-17. The flexible printed wiring board by which the surface obtained through the drying process was applied after apply | coating the resin composition varnish of Claim 18 or 19 to the predetermined part of a flexible printed wiring board. An electronic device incorporating the flexible printed wiring board according to claim 21 or 22.