TWI419949B - Adhesive composition and substance for flexible print wiring board - Google Patents

Description

Adhesive composition and substrate for flexible printed circuit board

The present invention relates to an adhesive composition and a substrate for a flexible printed circuit board. In particular, it can form a superior low dielectric constant. An adhesive composition having a low dielectric loss and other electrical properties, and an adhesive layer of a sufficient adhesion, and a substrate for a flexible printed circuit board using the same.

In recent years, with the lightness and thinness of communication devices such as electronic devices and mobile phones, most of the circuit designs of such communication devices use advantageous flexible circuit boards. The flexible circuit board has a structure in which an insulating thin film layer made of polyimide and a copper foil layer of a circuit board are integrated with an adhesive layer. The circuit board can be produced by etching a copper foil.

The adhesive composition forming the pressure-sensitive adhesive layer has good compatibility with a thermosetting resin such as an epoxy resin, and generally contains acrylonitrile for the purpose of imparting sufficient adhesion strength and toughness to the hard and brittle thermosetting resin. A copolymer (for example, an acrylonitrile-butadiene copolymer or a carboxyl group-modified acrylonitrile-butadiene copolymer, etc.) (for example, Patent Documents 1 to 3).

JP-A-2002-235063, JP-A-2002-235063, JP-A-2002-235063

[Disclosure of the Invention]

However, when the copolymer containing the acrylonitrile contains a certain amount of acrylonitrile or more, the electrical characteristics of the adhesive layer formed, particularly the low dielectric constant or low dielectric loss, are deteriorated. In the future, in order to increase the density of flexible circuits, it is expected that the adhesive layer will not only have adhesive properties but also excellent electrical properties (especially low dielectric constant and low dielectric loss).

In view of the problems of the prior art, the present invention provides a structural unit containing (A) a monomer derived from a monomer having at least two (a-1) ethylenic polymerizable unsaturated groups. a copolymer with a structural unit derived from a monomer having an alcoholic hydroxyl group, (B) a thermosetting resin, and (C) a curing agent; in the high density of the flexible circuit, the adhesive property can be sufficiently maintained, and the electric power is excellent. A characteristic adhesive composition.

In the work of the present invention, in order to achieve this problem, it has been found that the problem can be attained by including a specific copolymer, a thermosetting resin, and a curing agent, and the present invention has been completed.

That is, according to the present invention, the following adhesive composition and substrate for a flexible printed circuit board can be provided.

[1] An adhesive composition comprising: (A) a structural unit containing a monomer having at least two (a-1) ethylenic polymerizable unsaturated groups, and a member (a-2) a copolymer of a structural unit of an alcoholic hydroxyl group monomer, (B) a thermosetting resin, and (C) a curing agent.

[2] The adhesive composition according to [1] above, wherein the ratio of the (a-1) structural unit is 50 to 95% with respect to 100% by mole of the total structural unit constituting the (A) copolymer. The ratio of the molar % and the (a-2) structural unit is 5 to 50 mol% with respect to 100 mol% of the total structural unit constituting the (A) copolymer.

[3] The adhesive composition according to [1] above, wherein the (A) copolymer further contains a selected from the group consisting of (a-3) styrene, a styrene derivative, (meth)acrylic acid, and (a) At least one structural unit in which the acrylic acid derivatives are grouped.

[4] The adhesive composition according to [3] above, wherein the ratio of the (a-1) structural unit is 50 to 90% with respect to 100% by mole of the total structural unit constituting the (A) copolymer. The ratio of the molar % and the (a-2) structural unit is 5 to 45 mol% with respect to 100 mmol% of the total structural unit constituting the (A) copolymer, and the (a-3) structural unit The ratio is 1 to 25 mol% with respect to 100 mol% of the total structural unit constituting the (A) copolymer.

[5] The adhesive composition according to [1] above, wherein the (a-1) structural unit is a structural unit derived from a diene monomer.

[6] The adhesive composition according to [1] above, wherein the (a-2) structural unit is a structural unit derived from a hydroxyalkyl (meth) acrylate.

[7] The adhesive composition according to [1] above, wherein the ratio of the structural unit derived from (a-4) acrylonitrile contained in the (A) copolymer is relative to the structure of the (A) copolymer The total structural unit is 100 mol%, which is 5 mol% or less.

[8] The adhesive composition according to [1] above, wherein the (B) thermosetting resin contains an epoxy resin.

[9] The adhesive composition according to the above [1], wherein the (A) copolymer contains an alkali metal ion in an amount of 50 ppm or less.

[10] A substrate for a flexible printed circuit board, comprising: an insulating thin film layer, a circuit board, and an adhesive composition according to the above [1], and disposed on the insulating thin film layer And an adhesive layer in which the insulating thin film layer and the circuit board are adhered to each other between the circuit boards.

The adhesive composition of the present invention can form an adhesive layer which can maintain sufficient adhesive properties and has excellent electrical properties (especially, low dielectric constant, low dielectric loss).

The substrate for a flexible printed circuit board of the present invention has an adhesive layer capable of maintaining sufficient adhesive properties and having excellent electrical characteristics (especially, low dielectric constant and low dielectric loss), and can be made thinner ( Lightweight) and high density.

[Best form for implementing the invention]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below, and the present invention is not limited to the embodiments. The following embodiments can be appropriately modified and improved based on the general knowledge of the present invention without departing from the gist of the present invention.

<1> Adhesive Composition The adhesive composition of the present invention contains: (A) a structural unit containing a monomer having at least two (a-1) ethylenic polymerizable unsaturated groups, and having (a) -2) a copolymer of a structural unit of a monomer of an alcoholic hydroxyl group (hereinafter also referred to as (A) copolymer], (B) a thermosetting resin, and (C) a curing agent.

With such a configuration, it is possible to form an adhesive layer which can maintain sufficient adhesive properties and has excellent electrical characteristics (especially low dielectric constant and low dielectric loss).

Moreover, it is preferable that the adhesive composition of the present invention contains (A) a structural unit derived from a monomer having at least two (a-1) ethylenic polymerizable unsaturated groups, and A-2) a structural unit of a monomer of an alcoholic hydroxyl group, which is derived from a group selected from the group consisting of (a-3) styrene, a styrene derivative, a (meth)acrylic acid, and a (meth)acrylic acid derivative. A copolymer of at least one structural unit [hereinafter referred to as (A) copolymer], (B) a thermosetting resin, and (C) a curing agent.

With such a configuration, it has sufficient adhesion and heat resistance to form a low dielectric constant. Adhesive layer with excellent dielectric properties such as low dielectric loss. The details of each component are as follows.

Further, the following structural units derived from styrene and styrene derivatives are referred to as (a-3-1) structural units; structural units derived from (meth)acrylic acid and (meth)acrylic acid derivatives are referred to as (a- 3-2) Construction unit.

<1-1> (A) Copolymer: The (A) copolymer contained in the adhesive composition of the present invention contains a monomer derived from at least two (a-1) ethylenically polymerizable unsaturated groups. The structural unit [hereinafter referred to as (a-1) structural unit] and the structural unit derived from the monomer having the (a-2) alcoholic hydroxyl group [hereinafter referred to as (a-2) structural unit].

(a-1) The structural unit is not limited to those derived from a monomer having at least two ethylenic polymerizable unsaturated groups. The monomer having at least two ethylene polymerizable unsaturated groups is, for example, a diene monomer or the like. The diene monomer is 1,3-butadiene, dimethylbutadiene, chloroprene, 1,3-pentadiene or isoprene.

The ratio of the (a-1) structural unit is preferably 100 to 95% by mole, more preferably 55 to 85 % by mole, based on 100% by mole of the total structural unit constituting the (A) copolymer. Good for 60~85%. (a-1) When the ratio of the structural unit is in the above range, the obtained copolymer has rubber elasticity, and sufficient adhesion can be obtained. Further, when the ratio of the (a-1) structural unit is less than 50 mol%, the adhesive strength may be lowered. On the other hand, when the ratio of the structural unit (a-1) exceeds 95 mol%, the compatibility with the thermosetting resin to be blended is lowered.

(a-2) The structural unit is not limited to those derived from a monomer having an alcoholic hydroxyl group. Conventionally, a flexible circuit board of a communication device such as an electronic device or a mobile phone includes an insulating thin film layer made of an epoxy resin or the like, and a circuit board made of a copper foil layer or the like, which is adhered by an adhesive layer. The insulating thin film layer is formed by adhering to the circuit board. This adhesive layer is formed by a composition containing a copolymer containing a structural unit derived from acrylonitrile because it has good compatibility with the epoxy resin constituting the insulating film layer. Here, the ratio of the (A) copolymer (a-4) derived from the acrylonitrile structural unit [hereinafter referred to as (a-4) structural unit] in the adhesive composition of the present invention is 5 mol. % or less, since (a-2) structural unit is contained, (a-2) structural unit functions as a polar group of a copolymer. Therefore, the adhesive layer formed of the adhesive composition of the present invention can provide good compatibility with an insulating film layer made of an epoxy resin or the like.

The monomer having an alcoholic hydroxyl group constituting the structural unit of (a-2) is preferably, for example, a (meth) acrylate having an alcoholic hydroxyl group. The monomer having an alcoholic hydroxyl group is, for example, a hydroxyethyl (meth)acrylate, a hydroxypropyl (meth)acrylate, or a hydroxyalkyl (meth)acrylate such as hydroxybutyl (meth)acrylate; 2-hydroxy-3-phenoxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate monostearate, polyethylene glycol (meth)acrylic acid Ester, polypropylene glycol (meth) acrylate; epoxy (meth) acrylate; Epoxy (meth) acrylates, for example, by diglycidyl ether of bisphenol A, diglycidyl ether of diol, etc., with (meth)acrylic acid, hydroxyalkyl (methyl) It is obtained by the reaction of acrylate or the like.

The ratio of the (a-2) structural unit is preferably from 5 to 50 mol%, more preferably from 15 to 45 mol%, based on 100 mol% of the total structural unit constituting the (A) copolymer. Good for 15~40%. When the ratio of the structural unit (a-2) is in the above range, the obtained copolymer has good compatibility with the thermosetting resin to be blended, has toughness, and has sufficient adhesiveness.

Further, the (A) copolymer may contain other structural units (hereinafter referred to as other structural units (α) in addition to the (a-1) structural unit and the (a-2) structural unit. The other structural unit (α) is not particularly limited as long as it is a monomer which can be copolymerized with a monomer having at least two of the ethylenic polymerizable unsaturated groups and a monomer having an alcoholic hydroxyl group. Further, the ratio of the other structural unit (α) is preferably from 5 to 30 mol%, more preferably from 5 to 25 mol%, based on 100 mol% of the total structural unit of the (A) copolymer. Good for 1~15 moles. However, when the other structural unit (α) is a structural unit derived from acrylonitrile, the ratio of other structural units (α) (structural unit derived from acrylonitrile) is 100% by mole relative to the (A) copolymer. It is preferably 5 mol% or less. Also, it is most preferable that the structural unit derived from acrylonitrile is not contained.

The other structural unit (α) includes, for example, a monomer derived from a monomer having a carboxyl group and a monomer having an epoxy group.

The monomer having a carboxyl group is, for example, an unsaturated carboxylic acid such as (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, tetradecanoic acid or cinnamic acid; Non-polymerizable polycarboxylic acid such as acid or adipic acid, and hydroxyl group-containing unsaturated compound such as (meth)allyl alcohol or 2-hydroxyethyl (meth)acrylate, and ester containing free carboxyl group such as monoester , as well as its salt and so on.

The monomer having an epoxy group may be (meth)allyl epoxidized propyl ether, (meth)acrylic acid propyl propyl ester, (meth)acrylic acid 3,4-oxycyclohexyl ester or the like.

The (A) copolymer contained in the adhesive composition of the present invention further contains a derivative selected from the group consisting of (a-3) styrene, styrene derivative, (meth)acrylic acid, and (meth)acrylic acid derivative. At least one structural unit of the group [hereinafter referred to as (a-3) structural unit] is preferred.

That is, the (A) copolymer contained in the adhesive composition of the present invention contains a structural unit [(a-1) structure derived from a monomer having at least two (a-1) ethylenic polymerizable unsaturated groups. Unit], with a structural unit derived from a monomer having an (a-2) alcoholic hydroxyl group [(a-2) structural unit], and derived from (a-3) styrene, a styrene derivative, (a At least one structural unit (hereinafter referred to as (a-3) structural unit) in which the acrylic acid and the (meth)acrylic acid derivative are grouped is preferable.

A flexible circuit board used in a communication device such as an electronic device or a mobile phone generates heat as the communication device is used. Further, when the flexible circuit board generates heat (when the adhesive layer is heated), the adhesive layer is decomposed, and the adhesive force is lowered. Therefore, the adhesive layer provided in the flexible circuit board is required to have heat resistance.

The adhesive composition of the present invention contains (A) a copolymer which has a low dielectric constant by having a (a-3) structural unit and having sufficient adhesion. An adhesive layer having excellent dielectric properties such as low dielectric loss and an adhesive layer having heat resistance.

More specifically, (A) the copolymer contains a structural unit derived from styrene, a structural unit derived from a styrene derivative, or a structural unit of the two, and (A) a high Tg of the copolymer The formed adhesive layer exhibits heat resistance. Further, when the (A) copolymer contains a structural unit derived from (meth)acrylic acid, a structural unit derived from a (meth)acrylic acid derivative, or a structural unit of both, the structural unit is heated by (B) The reaction of the curable resin increases the crosslinking density, and the formed adhesive layer exhibits heat resistance. The reaction with (B) a thermosetting resin, specifically, a carboxyl group and an epoxy group are reacted to form a crosslinked structure, whereby the crosslinking density is increased by the reaction, and the formed adhesive layer is made to have heat resistance ( Increase the Tg of the hardened material). Further, the (A) copolymer can have a high Tg and can exhibit superior electrical characteristics by containing a structural unit derived from styrene, a structural unit derived from a styrene derivative, or a structural unit of both of them. .

Further, a structural unit derived from styrene or a styrene derivative is referred to as a (a-3-1) structural unit; a structural unit derived from a (meth)acrylic acid or a (meth)acrylic acid derivative is referred to as (a- 3-2) Construction unit. The details are as follows.

(A) When the copolymer contains the structural unit (a-3), the structural unit (a-1) contained in the (A) copolymer is the same as the above-exemplified one.

(A) When the copolymer contains (a-3) structural unit, the ratio of (a-1) structural unit is 50 to 90 mol% with respect to 100 mol% of the total structural unit constituting the (A) copolymer. Preferably, it is preferably 55 to 90 mol%, and the best is 60 to 85 mol%. When the ratio of the structural unit (a-1) is within the above range, the obtained copolymer has rubber elasticity, and sufficient adhesion can be obtained. Further, when the ratio of the (a-1) structural unit is less than 50 mol%, the adhesive force is lowered; on the other hand, when the ratio of the (a-1) structural unit exceeds 95 mol%, The compatibility of the thermosetting resin may be lowered.

(A) When the copolymer contains the structural unit (a-3), the structural unit (a-2) contained in the (A) copolymer is the same as the above-exemplified one.

(A) When the copolymer contains (a-3) structural unit, the ratio of (a-2) structural unit is 5 to 45 mol% with respect to 100 mol% of the total structural unit constituting the (A) copolymer. Preferably, it is preferably 7~30% by mole, and the best is 10~20% by mole. When the ratio of the structural unit (a-2) is within the above range, the obtained polymer has good compatibility with the thermosetting resin to be blended, and has toughness and sufficient adhesion.

The styrene and styrene derivatives used in the structural unit (a-3) include, for example, α-methylstyrene, o-methoxystyrene, p-hydroxystyrene, p-isopropenylphenol, and the like. Group vinyl compounds. Further, the (meth)acrylic acid and (meth)acrylic acid derivatives used in the structural unit (a-3) include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. Propyl ester, butyl (meth)acrylate, hexyl (meth)acrylate, (dode)alkyl (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylic acid Ester and the like. Further, the (a-3) structural unit is derived from at least one structural unit selected from the group consisting of styrene, styrene derivatives, (meth)acrylic acid, and (meth)acrylic acid derivatives. They may be used alone or in combination of two or more.

(a-3) The proportion of the structural unit is preferably from 1 to 25 mol%, more preferably from 1 to 20 mol%, based on 100 mol% of the total structural unit constituting the (A) copolymer. It is 1~18 mol%. When the ratio of the structural unit (a-3) is within the above range, the heat resistance of the cured product obtained from the adhesive composition is good.

(A) When the copolymer contains (a-3) structural unit, the (A) copolymer may contain other components besides (a-1) structural unit, (a-2) structural unit, and (a-3) structural unit. The structural unit [hereinafter referred to as other structural units (β)]. The other structural unit (β) is a monomer having at least two of the ethylenic polymerizable unsaturated groups, a monomer having an alcoholic hydroxyl group, and a selected from the group consisting of styrene, a styrene derivative, and (methyl) There is no particular limitation on the at least one copolymerizable monomer in which the acrylic acid and the (meth)acrylic acid derivative are grouped.

Further, the ratio of the other structural unit (β) is preferably 1 to 20 mol%, more preferably 1 to 15 mol%, and most preferably 100 mol% of the total structural unit of the (A) copolymer. Good for 1~10 mol%. However, when the other structural unit (β) is a structural unit derived from (a-4) acrylonitrile, the ratio of other structural units (β) [from (a-4) acrylonitrile structural unit] is relative to ( A) 100% by mole of the copolymer, and it is necessary to be 5 mol% or less. Also, it is most preferred that the structural unit derived from (a-4) acrylonitrile is not contained.

The method for producing the (A) copolymer is not particularly limited; for example, an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, or the like can be used, and among them, an emulsion polymerization method is preferred.

When it is produced by emulsion polymerization, first, each monomer is emulsified in water using a surfactant. Thereafter, a radical polymerization initiator such as a peroxide catalyst or a redox catalyst to which a polymerization initiator is added is polymerized at 0 to 50 ° C in accordance with a desired molecular weight modifier such as a thiol compound or a terpene compound. Next, after the predetermined polymerization conversion ratio is reached, a reaction inhibitor such as N,N-diethylhydroxylamine is added to stop the polymerization reaction. After the polymerization reaction is stopped, the unreacted monomer in the polymerization system is removed by steam distillation or the like to obtain a copolymer latex. The obtained copolymer latex is added to a predetermined concentration of an aqueous electrolyte solution, and the (A) copolymer in the copolymer latex is solidified (destruction of the latex), and then the (A) copolymer is isolated by washing with water and drying.

(A) a method of solidifying a copolymer, which comprises adding a copolymer latex to a predetermined concentration of an aqueous electrolyte solution for salting out, and a nonionic surfactant when using a nonionic surfactant of a surfactant; A method in which the (A) copolymer is solidified by heating above the cloud point. Further, when a surfactant other than the nonionic surfactant is used, a nonionic surfactant is added after the polymerization, and the copolymer (A) can be solidified by heating at a cloud point or higher.

The surfactant is not particularly limited, and for example, an alkyl sulfate salt, a polyethylene oxide alkyl ether sulfate salt, an alkylbenzenesulfonate, an alkyl diphenyl ether disulfonate, an alkene can be used. An anionic surfactant such as dipotassium succinate or sodium alkane sulfonate; a cationic surfactant such as an alkylamine salt or a fourth ammonium salt; a polyethylene oxide alkyl ether or a polyethylene oxide alkyl group; Nonionic surfactants such as allyl ether, polyethylene oxide fatty acid ester, polyethylene oxide sorbitan fatty acid ester, fatty acid monoglyceride, and amphoteric surfactant; and reactive emulsifier. These surfactants may be used alone or in combination of two or more.

(A) The copolymer is preferably blended in an amount of 50 to 200 parts by mass based on 100 parts by mass of the (B) thermosetting resin, and more preferably 70 to 150 parts by mass. When the blending amount is in the above range, there is an advantage that the adhesiveness of the obtained adhesive layer is improved, and peeling does not occur in long-term use. Further, it improves the compatibility of the (A) copolymer with other components while improving the heat resistance of the resulting adhesive layer.

(A) The glass transition temperature (Tg) of the copolymer is preferably -90 to 0 ° C, more preferably -80 to -10 ° C, most preferably -70 to -20 ° C, (A) glass transition temperature of the copolymer When the (Tg) is less than -90 ° C, the heat resistance of the copolymer is lowered. On the other hand, when it exceeds 0 ° C, the copolymer has a tendency to lose rubber elasticity. In addition, in this specification, "glass transition temperature (Tg)" means the value measured by the differential scanning calorimeter. Specifically, the (A) copolymer was heated and dried, and then analyzed by a differential scanning calorimeter (manufactured by Seiko Instruments Inc., trade name "EXSTAR 6000 DSC" at a temperature increase rate of 10 ° C /min.

(A) The Mooney viscosity (ML ₁₊₄ , 100 ° C) of the copolymer is preferably from 40 to 90, more preferably from 45 to 85, most preferably from 50 to 80. (A) When the Mooney viscosity of the copolymer is less than 40, the viscosity of the rubber is too low, the adhesion is strong, and the productivity is lowered. On the other hand, when it exceeds 90, the workability is lowered. In addition, the term "Money's viscosity" as used in this specification refers to the use of the ML rotor and preheating according to the JIS K 6300 standard by the Mooney test machine (trade name "MOONEY MV 2000E" manufactured by Alufa Technology Co., Ltd.). The value of the rotor was measured for 4 minutes in 1 minute and measured at a temperature of 100 °C.

Further, the amount of the alkali metal ion contained in the (A) copolymer is preferably 50 ppm or less, more preferably 30 ppm or less, and most preferably 20 ppm or less. When the content of the alkali metal ion exceeds 50 ppm, there is a problem that insulation is poor. Further, the alkali metal ions are preferably sodium ions or potassium ions. That is, the total amount of sodium ions and potassium ions is preferably 500 ppm or less.

Further, in the adhesive composition of the present invention, the ratio of the structural unit derived from (a-4) acrylonitrile contained in the (A) copolymer is 100 mol% based on the total structural unit of the (A) copolymer. 5 mol% or less is more preferably 3 mol% or less, more preferably 2 mol% or less, and most preferably 1 mol% or less. Also, the ratio of the most optimal structural unit derived from acrylonitrile is 0 mol%. That is, it is completely excluded.

Here, the conventional adhesive composition contains a copolymer containing a structural unit derived from acrylonitrile in a predetermined amount or more from the viewpoint of compatibility with a thermosetting resin, particularly an epoxy resin; The copolymer of the structural unit may, for example, be an acrylonitrile-butadiene copolymer or a carboxyl group-modified acrylonitrile-butadiene copolymer. For example, Patent Document 1 has an acrylonitrile-butadiene copolymer containing a copolymer containing a structural unit derived from acrylonitrile; the acrylonitrile-butadiene copolymer has an acrylonitrile content of 10 to 50 mol% of an adhesive. The disclosure of the composition. However, the adhesive layer formed by the adhesive composition is insufficient in electrical characteristics (especially low dielectric constant, low dielectric loss), leaving room for improvement.

On the other hand, in the adhesive composition of the present invention, the ratio of the structural unit derived from (a-4) acrylonitrile contained in the (A) copolymer is 100 mol% with respect to the total structural unit constituting the (A) copolymer. Preferably, it is 5 mol% or less; in such a case, the deterioration of electrical characteristics due to the structural unit derived from acrylonitrile is avoided. Further, since the (A) copolymer contains (a-2) structural units, it is assumed that the ratio of the (a-4) structural unit is 5 mol% or less, and good compatibility with the epoxy resin can be improved. The adhesive layer formed of the adhesive composition of the present invention containing such a (A) copolymer has excellent compatibility with a thermosetting resin, particularly an epoxy resin, and exhibits superior electrical properties (especially Low dielectric constant. Low dielectric loss).

<1-2> (B) Thermosetting Resin: The (B) thermosetting resin contained in the adhesive composition of the present invention is not particularly limited, and an epoxy resin, a phenol resin or the like can be used. Among these, epoxy resin is preferred. The epoxy resin is preferably one having a structure having at least two epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthol novolac type epoxy resin, biphenyl novolac type epoxy resin, phenol novolac type epoxy Resin, cresol type epoxy resin, and the like. Among these, a bisphenol type epoxy resin is preferred. Further, the (B) thermosetting resin may be used singly or in combination of two or more kinds. Further, in order to impart flame retardancy, a halogenated epoxy resin such as a brominated epoxy resin may be added to the epoxy resin.

<1-3> (C) Hardener: The (C) hardener contained in the adhesive composition of the present invention is not particularly limited, and is, for example, diaminodiphenylmethane or diaminodiphenyl sulfide. Amines such as diaminodiphenyl sulfonic acid and diaminobenzophenone; imidazole resin, 2-alkyl-4-methylimidazole, 2-phenyl-4-alkylimidazole, etc. Derivatives; acid anhydrides such as phthalic anhydride and trimellitic anhydride; phenolic resins; polysulfide resins; polyvinyl phenols; dicyanamide diamine, dibasic acid diterpenes, organoborons, organophosphines, anthracenes And such salt. Further, these may be used alone or in combination of two or more. Further, for the purpose of promoting the hardening reaction, a curing accelerator may be used in combination with the (C) curing agent. Here, the term "hardener" as used herein means a person who forms a self-crosslinking structure and does not form a self-crosslinking structure, and includes a person who promotes a crosslinking reaction. The "hardening accelerator" means a person who increases the crosslinking reaction of the curing agent.

The amount of the curing agent (C) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the (B) thermosetting resin. (C) When the amount of the curing agent is less than 0.1 part by mass, the curing is insufficient. On the other hand, when it exceeds 20 parts by mass, the storage stability may be lowered.

<1-4> Other additives: In addition to the (A) copolymer, (B) thermosetting resin, and (C) hardener, the adhesive composition of the present invention may contain an organic solvent and a close aid depending on the demand. Agent, flattening agent, inorganic filler, polymer additive, reactive diluent, wettability improver, surfactant, plasticizer, antioxidant, antistatic agent, antifungal agent, humidity control agent, flame retardant and others Additives, etc. These additives can be used in an amount that does not impair the effects of the present invention.

The organic solvent is added to improve the viscosity of the adhesive composition, adjust the viscosity or storage stability; such an organic solvent is not particularly limited. There are ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether Propylene glycol monoalkyl ether; propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether and other propylene glycol dialkyl ethers; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol Propylene glycol monoalkyl ether acetate such as monopropyl ether acetate or propylene glycol monobutyl ether acetate; cellosolve such as ethyl cellosolve or butyl cellosolve; carbitol such as butyl carbitol; Lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, and isopropyl lactate; ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate , an aliphatic carboxylic acid ester such as isoamyl acetate, isopropyl propionate, n-butyl propionate or isobutyl propionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate , methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, etc. Its esters; aromatic hydrocarbons such as toluene and xylene; ketones such as 2-butanone (methyl ethyl ketone), 2-heptanone, 3-heptanone, 4-heptanone and cyclohexanone; N-dimethyl a decylamine such as formamide, N-methylacetamide, N,N-dimethylacetamide or N-methylpyrrolidone; or a lactone such as γ-butyrolactone. Among these, aromatic hydrocarbons and ketones are preferred. These organic solvents may be used singly or in combination of two or more kinds.

<2> Preparation of varnish containing adhesive composition: A varnish containing the adhesive composition of the present invention can be prepared as follows. First, (B) a thermosetting resin and (A) a copolymer are added to the organic solvent, and the mixture is completely dissolved using a stirrer. Thereafter, (C) a hardener is added to prepare a homogeneous solution having a solid concentration of about 40 (35 to 45)%, that is, a varnish containing an adhesive composition.

<3> Substrate for a flexible printed circuit board: The substrate for a flexible printed circuit board of the present invention is provided with an insulating thin film layer, and is formed on the circuit board by the adhesive composition of the present invention, and is disposed on the insulating film. An adhesive layer between the layer and the circuit board to which the insulating thin film layer and the circuit board are adhered. Since the adhesive layer formed of the adhesive composition of the present invention is provided, there is an advantage that the substrate for a flexible printed circuit board can be made thinner (lighter) and higher in density.

In the substrate for a flexible printed circuit board of the present invention, for example, the varnish containing the above-described adhesive composition can be applied to an insulating thin film layer, and a circuit board is placed on the coating film and dried. The circuit board can be formed by, for example, copper foil, aluminum foil, silver foil, gold foil, or the like.

The method of applying the varnish containing the adhesive composition to the insulating film layer may be, for example, a dipping method, a spray method, a bar coating method, a roll coating method, or a spin coating method. Further, the insulating film layer may be, for example, a polyimide film, a polyester film, a polyethylene naphthalate film, or a polyether quinone film.

In addition, the substrate for a flexible printed circuit board can be bonded to a substrate for a flexible printed circuit board having a multilayer shape of two or more.

[Examples]

The present invention is specifically described below on the basis of the examples, and the present invention is not limited to the examples. In addition, "parts" and "%" in the examples and comparative examples are all quality standards unless otherwise specified.

The (A-1) copolymer ~(A-11) copolymer was synthesized by the following method and used in each of Examples and Comparative Examples.

(Synthesis Example 1) [(A-1) Synthesis of Copolymer]

An aqueous solution of 5 parts by mass of sodium (dodecylbenzenesulfonate) dissolved, 40 parts by mass of butadiene (61.6 mol%) as a raw material monomer, and 60 parts by mass of 2-hydroxyethyl methacrylate (38.4) Moer %) placed into the autoclave. Next, 0.2 parts by mass of a tertiary (dodecyl)alkyl mercaptan as a molecular weight modifier was added to the autoclave, and an oxygenation catalyst was added to adjust the temperature to 10 °C. Thereafter, 0.01 parts by mass of a p-alkyl hydroxide as a polymerization initiator was added, and emulsion polymerization was carried out until the polymerization conversion ratio was 75%. Next, N,N-diethylhydroxylamine as a reaction inhibitor is added to obtain a copolymer latex. Water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxyethyl methacrylate). The solution from which the raw material monomer was removed was added to a 5% calcium chloride aqueous solution to precipitate a copolymer. The precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 80 ° C to isolate the (A-1) copolymer.

Further, the (A-1) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 70. In addition, the content of the alkali metal ion contained in the (A-1) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 20 ppm, K: 10 ppm (total content of alkali metal ions: 30 ppm) . The glass transition temperature (Tg) of the (A-1) copolymer was -12 °C. The content ratio of (a-1) structural unit was 65.0 mol% with respect to the total structural unit of (A-1) copolymer, and the content ratio of (a-2) structural unit was 35.0 mol%. Further, the content ratio of the structural unit derived from acrylonitrile is 0 mol%.

(Synthesis Example 2) [(A-2) Synthesis of Copolymer]

In addition to using an aqueous solution in which 10 parts by mass of the polyethylene oxide alkyl ether was dissolved, 75 parts by mass of butadiene (89.8 mol%) and 25 parts by mass of 2-hydroxybutyl methacrylate as a raw material monomer (10.2) The copolymer latex was obtained in the same manner as in Synthesis Example 1 except that 2 parts by mass of onion olefinene as a molecular weight modifier was used. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water and dried by a blow dryer set at 80 ° C to isolate the (A-2) copolymer.

In addition, as for the (A-2) copolymer, the Mooney viscosity [ML ₁₊₄ (100 ° C)] was measured using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 65. In addition, the content of the alkali metal ion contained in the copolymer (A-2) was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 15 ppm, K: 8 ppm (total content of alkali metal ions: 23 ppm) . The glass transition temperature (Tg) of the (A-2) copolymer was -48 °C. The content ratio of (a-1) structural unit was 90.0 mol% with respect to the total structural unit of the (A-2) copolymer, and the content ratio of (a-2) structural unit was 10.0 mol%. Further, the content ratio of the structural unit derived from acrylonitrile is 0 mol%.

(Synthesis Example 3) [(A-3) Synthesis of Copolymer]

The copolymer (A-3) was synthesized and isolated in the same manner as in Synthesis Example 2 except that 75 parts by mass (74.6 mol%) of butadiene as a raw material and 25 parts by mass of acrylonitrile (25.4 mol%) were used.

The (A-3) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 72. In addition, the content of the alkali metal ion contained in the (A-3) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 17 ppm, K: 7 ppm (total content of alkali metal ions: 24 ppm) . The glass transition temperature (Tg) of the (A-3) copolymer was -42 °C. The content ratio of (a-1) structural unit was 75.5 mol% with respect to the total structural unit of (A-3) copolymer, and the content ratio of (a-2) structural unit was 0 mol%. Further, the content ratio of the structural unit derived from acrylonitrile was 24.5 mol%.

(Synthesis Example 4) [(A-4) Synthesis of Copolymer]

In addition to using an aqueous solution in which 10 parts by mass of the polyethylene oxide alkyl ether was dissolved, 72 parts by mass of butadiene (86.1 mol%) and 25 parts by mass of 2-hydroxybutyl methacrylate as a raw material monomer (10.2) The copolymer latex was obtained in the same manner as in Synthesis Example 1 except that 3 parts by mass of acrylonitrile (3.7 mol%) was used as the molecular weight modifier. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 80 ° C to isolate the (A-4) copolymer.

The (A-4) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 70. Further, the content of the alkali metal ion contained in the copolymer (A-4) was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 16 ppm, K: 8 ppm (total content of alkali metal ions: 24 ppm) ). The glass transition temperature (Tg) of the (A-4) copolymer was -44 °C. The content ratio of (a-1) structural unit was 76.5 mol% with respect to the total structural unit of (A-4) copolymer, and the content ratio of (a-2) structural unit was 10.0 mol%. Further, the content ratio of the structural unit derived from acrylonitrile was 3.5 mol%.

(Synthesis Example 5) [(A-5) Synthesis of Copolymer]

In addition to using an aqueous solution in which 10 parts by mass of the polyethylene oxide alkyl ether was dissolved, 30 parts by mass of butadiene (55.6 mol%) and 70 parts by mass of 2-hydroxybutyl methacrylate as a raw material monomer (45.4) The copolymer latex was obtained in the same manner as in Synthesis Example 1 except that 2 parts by mass of onion olefinene as a molecular weight modifier was used. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 80 ° C to isolate the (A-5) copolymer.

The (A-5) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 69. In addition, the content of the alkali metal ion contained in the (A-5) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Tech Co., Ltd.), Na: 15 ppm, K: 5 ppm (total content of alkali metal ions: 20 ppm) ). The glass transition temperature (Tg) of the (A-5) copolymer was -3 °C. The content ratio of (a-1) structural unit was 56.5 mol% with respect to the total structural unit of (A-5) copolymer, and the content ratio of (a-2) structural unit was 43.5 mol%. Further, the content ratio of the structural unit derived from acrylonitrile is 0 mol%.

(Synthesis Example 6) [(A-6) Synthesis of Copolymer]

5 parts by mass of an aqueous solution of sodium dodecylbenzenesulfonate, 55 parts by mass of butadiene as a raw material monomer (74.4 mol%), and 25 parts by mass of 2-hydroxybutyl methacrylate (11.6) Molex%) and 20 parts by mass of styrene (14.0 mol%) were placed in an autoclave. Next, 0.2 parts by mass of a tertiary (dodecyl)alkyl mercaptan as a molecular weight modifier was added to the autoclave, and a reducing catalyst was reduced to adjust the temperature to 10 °C. Thereafter, 0.01 parts by mass of a palladium hydroxide as a polymerization initiator was added, and emulsion polymerization was carried out until the polymerization conversion ratio was 75%. Next, N,N-diethylhydroxylamine as a reaction inhibitor is added to obtain a copolymer latex. Water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate, and styrene). The solution from which the raw material monomer was removed was added to a 5% calcium chloride aqueous solution to precipitate a copolymer. The precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 80 ° C to isolate the (A-6) copolymer.

In addition, as for the (A-6) copolymer, the Mooney viscosity [ML ₁₊₄ (100 ° C)] was measured using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 60. Further, the content of the alkali metal ion contained in the (A-6) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 22 ppm, K: 12 ppm (total content of alkali metal ions: 34 ppm) . The glass transition temperature (Tg) of the (A-6) copolymer was -23 °C. The content ratio of the (a-1) structural unit is 73.5 mol% with respect to the total structural unit of the (A-6) copolymer; (a-2) the content ratio of the structural unit is 12.0 mol%; (a-3) The content ratio of the structural unit [(a-3-2) structural unit] was 14.5 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 0 mol%.

(Synthesis Example 7) [(A-7) Synthesis of Copolymer]

In addition to using an aqueous solution in which 10 parts by mass of the polyethylene oxide alkyl ether was dissolved, 75 parts by mass (87.4 mol%) of butadiene as a raw material monomer, and 23 parts by mass of 2-hydroxyethyl methacrylate (11.1) The copolymer latex was obtained in the same manner as in Synthesis Example 1 except that 2 parts by mass of methacrylic acid (1.5 mol%) and 2 parts by mass of onion olefinene as a molecular weight modifier. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxyethyl methacrylate, and methacrylic acid). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by further blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 90 ° C to isolate the (A-7) copolymer.

In addition, as for the (A-7) copolymer, the Mooney viscosity [ML ₁₊₄ (100 ° C)] was measured using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 72. Further, the content of the alkali metal ion contained in the (A-7) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 11 ppm and K: 7 ppm (total content of alkali metal ions: 18 ppm) . The glass transition temperature (Tg) of the (A-7) copolymer was -47 °C. 100% by mole of the total structural unit of the (A-7) copolymer, the content ratio of the (a-1) structural unit is 87.4 mol%; and the content ratio of the (a-2) structural unit is 10.8 mol%; (a-3) The content ratio of the structural unit [(a-3-2) structural unit] was 1.8 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 0 mol%.

(Synthesis Example 8) [(A-8) Synthesis of Copolymer]

50 parts by mass (70.2 mol%) of butadiene as a raw material, 30 parts by mass of 2-hydroxybutyl methacrylate (14.4 mol%), 15 parts by mass of styrene (10.9 mol%), and The copolymer latex was obtained in the same manner as in Synthesis Example 2 except that 5 parts by mass of methacrylic acid (4.4 mol%) was used as the molecular weight modifier. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate, styrene, and methacrylic acid). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by further blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water and dried by a blow dryer set at 90 ° C to isolate the (A-8) copolymer.

Further, the (A-8) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 75. Further, the content of the alkali metal ion contained in the (A-8) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 12 ppm and K: 4 ppm (total content of alkali metal ions: 16 ppm) . The glass transition temperature (Tg) of the (A-8) copolymer was -14 °C. 100% by mole of the total structural unit of the (A-8) copolymer, the content ratio of the (a-1) structural unit is 70.0 mol%; and the content ratio of the (a-2) structural unit is 14.2 mol%; The content ratio of (a-3-1) structural unit was 10.2 mol%; the content ratio of (a-3-2) structural unit was 5.6 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 0 mol%.

(Synthesis Example 9) [Synthesis of (A-9) Copolymer]

In the same manner as in Synthesis Example 1, except that 65 parts by mass (67.2 mol%) of butadiene as a raw material, 25 parts by mass of acrylonitrile (26.3 mol%), and 10 parts by mass of methacrylic acid (6.5 mol%) were used. The copolymer (A-9) was synthesized and isolated.

In addition, as for the (A-9) copolymer, the Mooney viscosity [ML ₁₊₄ (100 ° C)] was measured using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 72. Further, the content of the alkali metal ion contained in the (A-9) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 20 ppm, K: 10 ppm (total content of alkali metal ions: 30 ppm) . The glass transition temperature (Tg) of the (A-9) copolymer was -25 °C. The content ratio of the (a-1) structural unit is 67.0 mol% with respect to the total structural unit of the (A-9) copolymer; (a-2) the content ratio of the structural unit is 0 mol%; (a-3) The content ratio of the structural unit [(a-3-2) structural unit] was 6.8 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 26.2 mol%.

(Synthesis Example 10) [(A-10) Synthesis of Copolymer]

The (A-10) copolymer was synthesized and isolated in the same manner as in Synthesis Example 2 except that 75 parts by mass of butadiene as a raw material (74.6 mol%) and 25 parts by mass of acrylonitrile (25.4 mol%) were used. .

In addition, as for the (A-10) copolymer, the Mooney viscosity [ML ₁₊₄ (100 ° C)] was measured using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 72. In addition, the content of the alkali metal ion contained in the (A-10) copolymer was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 17 ppm, K: 7 ppm (total content of alkali metal ions: 24 ppm) . The glass transition temperature (Tg) of the (A-10) copolymer was -42 °C. 100% by mole of the total structural unit of the (A-10) copolymer, the content ratio of the (a-1) structural unit is 74.2 mol%; (a-2) the content ratio of the structural unit is 0 mol%; (a-3) The content ratio of the structural unit is 0 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 25.8 mol%.

(Synthesis Example 11) [(A-11) Synthesis of Copolymer]

In addition to using an aqueous solution in which 10 parts by mass of the polyethylene oxide alkyl ether was dissolved, 70 parts by mass (84.5 mol%) of butadiene as a raw material monomer and 25 parts by mass of 2-hydroxybutyl methacrylate (10.3) In the same manner as in Synthesis Example 1, except that 2 parts by mass of methacrylic acid (1.5 mol%), 3 parts by mass of acrylonitrile (3.7 mol%), and 2 parts by mass of the onion olefin of the molecular weight modifier. That is, a copolymer latex is obtained. Thereafter, water vapor was blown into the obtained copolymer latex to remove unreacted raw material monomers (butadiene, 2-hydroxybutyl methacrylate). The solution from which the raw material monomer was removed was added to an aqueous solution of 5% ammonium sulfate (cloud point reducing agent), and the copolymer was precipitated by further blowing water vapor. Thereafter, the precipitated copolymer was washed with distilled water, and dried by a blow dryer set at 80 ° C to isolate the (A-11) copolymer.

Further, the (A-11) copolymer was measured for Mooney viscosity [ML ₁₊₄ (100 ° C)] using a Mooney tester (manufactured by Alufa Technology Co., Ltd.) to be 70. Further, the content of the alkali metal ion contained in the copolymer (A-11) was analyzed by an atomic absorption spectrophotometer (manufactured by Hitachi High-Technologies Corporation), and Na: 14 ppm and K: 4 ppm (total content of alkali metal ions: 18 ppm) . The glass transition temperature (Tg) of the (A-11) copolymer was -41 °C. 100% by mole of the total structural unit of the (A-11) copolymer, the content ratio of the (a-1) structural unit is 85.0 mol%; and the content ratio of the (a-2) structural unit is 10.2 mol%; (a-3) The content ratio of the structural unit [(a-3-2) structural unit] is 1.5 mol%. Further, the content ratio of the structural unit derived from (a-4) acrylonitrile was 3.3 mol%.

Further, the (a-1) structural unit and the (a-2) structural unit contained in the (A-1) copolymer ~(A-11) copolymer, the structural unit derived from acrylonitrile [(a-4) structure The content (ratio) of the unit] (% by mole) is shown in Table 1 and Table 2.

[Example 1]

70 parts by mass of (A-1) copolymer obtained in Synthesis Example 1 of (A) copolymer, and (B) epoxy resin of thermosetting resin (trade name: Yeppei 828, manufactured by Nippon Epoxy Co., Ltd. 50 parts by mass of "B-1" in the table, and (B) epoxy resin of thermosetting resin (trade name: Yeppei 1001, manufactured by Nippon Epoxy Co., Ltd., "B- 2") 50 parts by mass, 263 parts by mass of methyl ethyl ketone was added, and completely dissolved by a blender "MAZERA Z" (manufactured by Tokyo Scientific Instruments Co., Ltd.). Then, 5 parts by mass of (C) a hardening agent, diaminodiphenylmethane (trade name: Smither M, manufactured by Sumitomo Chemical Co., Ltd., "C-1" in the table) was added, and the mixture was mixed with the above mixer. A homogeneous solution. That is, a varnish containing an adhesive composition having a solid concentration of about 40% is obtained. The resulting varnish containing the adhesive composition was subjected to various evaluations as described below by separate methods.

<compatibility>

The varnish containing the adhesive composition was placed in a transparent glass bottle to visually confirm the turbidity of the solution and the presence or absence of the precipitate. When it is judged to be a homogeneous solution, it is described as "good"; when the solution is cloudy, it is "poor" when there is a precipitate.

<Electrical characteristics>

The varnish containing the adhesive composition was applied to a SUS plate whose surface was mirror-finished, and heated in a convection oven at 90 ° C for 15 minutes. Thereafter, the film was further heated at 170 ° C for 1 hour to form a 20 μm thick adhesive layer on the SUS plate. An aluminum electrode was formed on the adhesive layer, and dielectric constant and dielectric loss were measured at a frequency of 1 MHz by a dielectric constant/dielectric loss measuring machine (manufactured by Hyderabad Co., Ltd., LCR meter HP4248). .

<adhesiveness>

The varnish containing the adhesive composition was applied to a copper plate having a thickness of 1 mm, and heated in a convection oven at 90 ° C for 15 minutes. Thereafter, the film was further heated at 170 ° C for 1 hour to form a 20 μm thick adhesive layer on the SUS plate. On the adhesive layer, a polyimide film (Uchiyuki Co., Ltd., Optimus 75S) was placed on the adhesive layer, and then pressed at 130 ° C, 0.5 MPa, and 1 minute using a press (manufactured by Kansai Rolling Co., Ltd.). , to be fitted. Thereafter, the adhesive layer was hardened by heating in an oven at 170 °C. The thus obtained test plate (copper plate-adhesive layer-polyimine film) was subjected to a 90-degree peeling test by forming a slit having a width of 1 cm by a cutter on the side of the polyimide film. Specifically, a 90-degree peeling strength (kg/cm) was measured using an adhesion tester (manufactured by Yamamoto Gold Plaid Tester Co., Ltd.) in accordance with JIS C6481 (Test Method for Copper-Plyse Laminates for Printed Circuit Boards). The peel strength measured was used as an indicator of adhesion determination.

The results of the evaluations in this example were good in compatibility, the dielectric constant of the electrical characteristics was 3.4, the dielectric loss was 0.03, and the peeling strength was 1.1 kg/cm.

[Examples 2 to 4, Comparative Example 1]

An adhesive composition (a varnish containing an adhesive composition) was obtained in the same manner as in the above Example 1 except that the formulation shown in Table 2 was used. The evaluation results of the obtained adhesive compositions are shown in Table 3.

[Example 5]

70 parts by mass of (A-5) copolymer obtained in Synthesis Example 5 of (A) copolymer, and (B) epoxy resin of thermosetting resin (trade name: Yeppei 828, manufactured by Nippon Epoxy Co., Ltd. 50 parts by mass of "B-1" in the table, and (B) epoxy resin of thermosetting resin (trade name: Yeppei 1001, manufactured by Nippon Epoxy Co., Ltd., "B- 2") 50 parts by mass, 263 parts by mass of toluene was added, and completely dissolved by a blender "MAZERA Z" (manufactured by Tokyo Scientific Instruments Co., Ltd.). Then, 5 parts by mass of (C) a hardening agent, diaminodiphenylmethane (trade name: Smither M, manufactured by Sumitomo Chemical Co., Ltd., "C-1" in the table) was added, and the mixture was mixed with the above mixer. A homogeneous solution. That is, a varnish (adhesive composition) containing an adhesive composition having a solid concentration of about 40%. The obtained varnish containing the adhesive composition was evaluated for compatibility, electrical properties, and adhesion as described above, and the measurement of the glass transition temperature described below.

<glass transition temperature>

The viscoelasticity measurement was carried out by TMA/SS6100 (manufactured by Seiko Instruments Inc.), and the glass transition temperature (Tg) of the cured product was determined from the action of tan δ. The test conditions were such that the test piece had a thickness of 50 μm/width of 3 mm and a temperature increase rate of 5 ° C/min.

The results of the evaluations in this example were good in compatibility, the dielectric constant of electrical characteristics was 3.3, the dielectric loss was 0.02, the peeling strength was 1.2 kg/cm, and the glass transition temperature (Tg) was 140 °C.

[Examples 6 to 11, Comparative Examples 2, 3]

An adhesive composition (a varnish containing an adhesive composition) was obtained in the same manner as in the above Example 5 except for the formulation shown in Table 4. The evaluation results of the obtained adhesive compositions are shown in Table 4.

As shown in Tables 3 and 4, when the adhesive compositions of Examples 1 to 8 were used, it was found that the adhesive composition of Comparative Examples 1 to 3 can be used, and it is possible to maintain a sufficient adhesive property and have superior properties. An adhesive layer having electrical properties (especially low dielectric constant and dielectric loss).

[Industrial use]

The adhesive composition of the present invention can form an adhesive layer which can maintain sufficient adhesive properties and has excellent electrical properties (especially, low dielectric constant, low dielectric loss). The adhesive composition of the present invention is particularly suitable for an adhesive layer such as a substrate for a flexible printed circuit board of a communication device such as an electronic device or a mobile phone.

Claims (9)

An adhesive composition comprising: (A) a structural unit containing a monomer derived from at least two (a-1) ethylenically polymerizable unsaturated groups, and an alcoholic hydroxyl group derived from (a-2) a structural unit of the monomer, a copolymer with a structural unit derived from (a-4) acrylonitrile, (B) a thermosetting resin, and (C) a curing agent; wherein the (A) copolymer contains the same (a-2) The structural unit of the monomer of the alcoholic hydroxyl group is 5 to 45 mol% based on 100 mol% of the total structural unit constituting the copolymer (A), and the above is derived from (a-4) acrylonitrile. The ratio of the structural unit is 0 to 5 mol% with respect to 100 mol% of the total structural unit constituting the (A) copolymer. The adhesive composition of claim 1, wherein: the ratio of the structural unit (a-1) is 50 to 95 m per 100 mol% of the total structural unit constituting the copolymer (A). %, the ratio of the structural unit (a-2) described above is 5 to 45 mol% with respect to 100 mol% of the total structural unit constituting the copolymer (A). The adhesive composition of claim 1, wherein the (A) copolymer further comprises a styrene selected from the group consisting of (a-3) styrene, a styrene derivative, (meth)acrylic acid, and (methyl) At least one structural unit in which the acrylic acid derivatives are grouped. For example, the adhesive composition of claim 3, wherein: The ratio of the structural unit (a-1) is 50 to 90 mol% with respect to 100 mol% of the total structural unit constituting the copolymer (A), and the ratio of the structural unit (a-2) is relative to 100% by mole of the total structural unit of the copolymer (A) is 5 to 45 mol%, and the ratio of the structural unit (a-3) is 100 mol with respect to the entire structural unit constituting the (A) copolymer. % of ear, 1 to 25 mol%. The adhesive composition of claim 1, wherein the structural unit (a-1) is a structural unit derived from a diene monomer. The adhesive composition of claim 1, wherein the structural unit (a-2) is a structural unit derived from a hydroxyalkyl (meth) acrylate. The adhesive composition of claim 1, wherein the (B) thermosetting resin contains an epoxy resin. The adhesive composition according to claim 1, wherein the content of the alkali metal ion contained in the (A) copolymer is 50 ppm or less. A substrate for a flexible printed circuit board, comprising: an insulating thin film layer, a circuit board, and an adhesive film layer formed by the first aspect of the patent application; An adhesive layer adhered between the circuit board and the insulating film layer and the circuit board is adhered to each other.