WO2021079670A1

WO2021079670A1 - Adhesive composition for flexible printed wiring board, adhesive for flexible printed wiring board, and flexible printed wiring board

Info

Publication number: WO2021079670A1
Application number: PCT/JP2020/035562
Authority: WO
Inventors: 宇之中根
Original assignee: 三菱ケミカル株式会社
Priority date: 2019-10-23
Filing date: 2020-09-18
Publication date: 2021-04-29
Also published as: TW202134381A; KR20220087444A; CN114555749A; CN114555749B

Abstract

As an adhesive composition which exhibits excellent long term durability in moist heat environments and excellent adhesive properties, the present invention provides an adhesive composition for a flexible printed wiring board, which contains a polyester-based resin (A1) containing structural units derived from a polycarboxylic acid and structural units derived from a polyhydric alcohol, and which is characterized in that the polyester-based resin (A1) satisfies the requirements. [1] The ester bond concentration is 7 mmol/g or less. [2] The acid value is 3 mg KOH/g or more. [3] The glass transition temperature (Tg) is -5ºC or higher.

Description

Adhesive composition for flexible printed wiring board, adhesive for flexible printed wiring board and flexible printed wiring board

The present invention relates to an adhesive composition for a flexible printed wiring board containing a polyester resin and an adhesive obtained by curing the adhesive composition. More specifically, the present invention relates to an adhesive having high adhesiveness in addition to long-term durability in a moist heat environment, and an adhesive composition before the adhesive is cured.

Conventionally, polyester resins have excellent heat resistance, chemical resistance, durability, and mechanical strength, and are therefore used in a wide range of fields such as films, PET bottles, fibers, toners, electrical parts, adhesives, and adhesives. ing. Further, since the polyester resin has high polarity due to its polymer structure, it exhibits excellent adhesiveness to polar polymers such as polyester, polyvinyl chloride, polyimide and epoxy resin, and metal materials such as copper and aluminum. It has been known. Utilizing this property, its use as an adhesive for producing a metal-plastic laminate, for example, a flexible copper-clad laminate, a flexible printed circuit board, or the like is being studied.

For example, Patent Document 1 proposes a thermosetting adhesive sheet having excellent dimensional stability during curing and excellent adhesiveness, heat resistance, flexibility, electrical insulation, low dielectric constant and low dielectric loss tangent after curing. ing. In this thermosetting adhesive sheet, the total amount of the reactive functional group capable of reacting with at least one of the organic metal compound or the epoxy group-containing compound and the functional group having a hetero atom other than halogen is 0.01 mmol / g. As described above, it is formed from a thermosetting composition containing a resin of 9 mmol / g or less (for example, a polyester resin), an organic metal compound, and a trifunctional or higher functional epoxy group-containing compound.

Further, Patent Document 2 proposes a copolymerized polyester having excellent moisture-heat resistance and cation-acid resistance, compatibility with an epoxy resin, and adhesiveness, and an adhesive composition containing the same. This copolymerized polyester is composed of an aromatic dicarboxylic acid component, a dimerdiol, a first glycol, a second glycol or an oxyic acid, and an alkylene glycol having 2 to 10 carbon atoms.

Japanese Unexamined Patent Publication No. 2017-031301 Japanese Unexamined Patent Publication No. 2003-183365

However, in recent years, in addition to curability, heat resistance, and adhesiveness, long-term durability in a moist heat environment is required for adhesives used for flexible copper-clad laminates and flexible printed circuit boards. Also tends to be strongly demanded. However, when the polarity of the resin is lowered for the purpose of improving the moist heat durability, there is a problem that the adhesiveness is generally significantly lowered, and it is difficult to achieve both of these characteristics at a high level.

For example, in the technique disclosed in Patent Document 1, a large amount of polyvalent carboxylic acid or polyhydric alcohol having a long-chain alkyl group is used for the purpose of reducing the dielectric constant / dielectric loss tangent and water absorption, and thus adhesiveness. There was a problem such as a decrease in. Further, Patent Document 1 does not consider the point of long-term durability in a moist heat environment, and further improvement is required.

Further, when a copper-clad laminate or the like is produced using the adhesive composition disclosed in Patent Document 2, it is expected that the long-term durability in a moist heat environment is relatively excellent. However, the copolymerized polyester is inferior in adhesiveness and heat resistance because it contains an ether bond-containing glycol such as polypropylene glycol as a copolymerization component and is not given an acid value as a reaction point with an epoxy resin. There is a problem and further improvement is required.

Therefore, the present invention provides an adhesive composition having excellent long-term durability in a moist heat environment and further having high adhesiveness under such a background, and an adhesive obtained by curing the adhesive composition.

However, as a result of intensive studies in view of such circumstances, the present inventor has obtained an adhesive obtained by curing an adhesive composition containing a polyester resin (A1) that satisfies the following requirements for a long period of time in a moist heat environment. We have found the adhesive composition (first aspect) of the present invention, which has excellent durability and high adhesiveness.
[1] The ester bond concentration is 7 mmol / g or less.
[2] The acid value is 3 mgKOH / g or more.
[3] The glass transition temperature (Tg) is -5 ° C or higher.

In addition to the first aspect, the adhesive composition of the present invention can also be obtained by containing a polyester resin (A2) that satisfies the following requirements (second aspect).
[I] The above-mentioned multivalent carboxylic acids contain 25 mol% or more of aromatic polyvalent carboxylic acids.
[II] The above-mentioned multivalent carboxylic acids contain trivalent or higher valent carboxylic acids (x1) having an acid anhydride radix of 0 or 1.
[III] The ester bond concentration is 7 mmol / g or less.
[IV] The acid value is 3 mgKOH / g or more.

Further, the adhesive composition of the present invention can also be obtained by containing any of the following polyester-based resins (1) to (4) in addition to the above-mentioned first and second aspects (third aspect). ).
(1) A polyester resin (A3) having a glass transition temperature (Tg) of −5 ° C. or higher, a temperature of 23 ° C., and a dielectric loss tangent (α) of 0.005 or lower at 10 GHz under a relative humidity of 50% RH environment.
(2) A polyester resin (A4) having an acid value of 3 mgKOH / g or more, a temperature of 23 ° C., and a dielectric loss tangent (α) of 0.005 or less at 10 GHz under a relative humidity of 50% RH environment.
(3) Polyester resin having a glass transition temperature (Tg) of -5 ° C or higher, an acid value of 3 mgKOH / g or higher, a temperature of 23 ° C, and a dielectric loss tangent (α) of 0.005 or lower at 10 GHz under a relative humidity of 50% RH environment. (A5).
(4) A polyester resin (A6) having a dielectric loss tangent (α) of 0.003 or less at 10 GHz under a temperature of 23 ° C. and a relative humidity of 50% RH.

Furthermore, the present invention also provides an adhesive obtained by curing the above-mentioned adhesive composition.

The present invention also provides a flexible printed wiring board using the above adhesive.

As described with respect to Patent Document 1, a large amount of polyvalent carboxylic acid or polyhydric alcohol having a long-chain alkyl group is usually used to reduce the water absorption rate, but on the other hand, in an adhesive or moist heat environment. Long-term durability is reduced.
The present inventor optimizes the ester bond concentration, acid value, glass transition temperature, etc. by adjusting the composition of the monomers constituting the polyester resin, thereby providing excellent long-term durability in a moist heat environment, and at the same time. The present invention was completed by finding that it is also excellent in adhesiveness.

The adhesive composition according to one aspect of the present invention is an adhesive composition containing a polyester resin (A1) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. Since the polyester resin (A1) satisfies the following requirements, it has excellent effects of low moisture absorption, tack-free property before curing, initial adhesiveness after curing, and long-term durability in a moist heat environment. Play.
[1] The ester bond concentration is 7 mmol / g or less.
[2] The acid value is 3 mgKOH / g or more.
[3] The glass transition temperature (Tg) is -5 ° C or higher.

Further, the polyester resin (A1) contains aromatic polyvalent carboxylic acids as polyvalent carboxylic acids, and the content of the aromatic polyvalent carboxylic acids as a whole is 25 mol% or more. And, it becomes more excellent in long-term durability in a moist heat environment.

Further, when the polyester resin (A1) has a carboxy group in the side chain, it becomes superior in curing speed and heat resistance after curing.

Further, the polyester resin (A1) contains at least one selected from the group consisting of dimer acids as the multivalued carboxylic acids and dimer diols as the polyhydric alcohols, and the polyvalent carboxylic acids as a whole. When the total content (α + β) of the content of the dimer acids (α) and the content of the dimer diols (β) with respect to the total content of the polyhydric alcohols is 5 mol% or more, low hygroscopicity or a moist heat environment It will be excellent in long-term durability underneath.

Further, when the polyester resin (A1) contains a bisphenol skeleton-containing monomer as the polyhydric alcohols and the content of the bisphenol skeleton-containing monomer with respect to the entire polyhydric alcohols is 10 mol% or more, it is low. It becomes superior in moisture absorption and long-term durability in a moist heat environment.

The adhesive composition according to another aspect of the present invention is an adhesive composition containing a polyester resin (A2) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. Since the polyester resin (A2) satisfies the following requirements, it has low moisture absorption, excellent long-term durability in a moist heat environment, and excellent adhesiveness.
[I] The above-mentioned multivalent carboxylic acids contain 25 mol% or more of aromatic polyvalent carboxylic acids.
[II] The above-mentioned multivalent carboxylic acids contain trivalent or higher valent carboxylic acids (x1) having an acid anhydride radix of 0 or 1.
[III] The ester bond concentration is 7 mmol / g or less.
[IV] The acid value is 3 mgKOH / g or more.

When the glass transition temperature of the polyester resin (A2) is −5 ° C. or higher, the initial adhesiveness and tack-free property become superior.

If the polyester-based resin (A2) is a polyester-based resin obtained through a step of depolymerization using a polyvalent carboxylic acid (x1), the adhesiveness becomes better.

The polyester resin (A2) contains at least one selected from the group consisting of dimer acids as the polyvalent carboxylic acids and dimer diols as the polyhydric alcohols, and the dimer acids with respect to the entire polyvalent carboxylic acids. When the total content (α + β) of the content (α) and the content (β) of the dimerdiols with respect to the total content of the polyhydric alcohols is 5 mol% or more, it is under low hygroscopicity or in a moist heat environment. Becomes better in long-term durability.

When the polyester resin (A2) contains a bisphenol skeleton-containing monomer as the polyhydric alcohols and the content of the bisphenol skeleton-containing monomer with respect to the entire polyhydric alcohols is 10 mol% or more, the moisture absorption property is low. It becomes superior in long-term durability in a moist heat environment.

The adhesive composition according to another aspect of the present invention is an adhesive composition containing a polyester resin (A3) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. The polyester resin (A3) has a glass transition temperature (Tg) of -5 ° C or higher, a temperature of 23 ° C, and a dielectric loss tangent (α) of 0.005 or less at 10 GHz under a relative humidity of 50% RH environment. It has a dielectric constant and a low dielectric loss tangent, particularly a low dielectric loss tangent, and exhibits excellent effects on initial adhesiveness after curing and long-term durability in a moist heat environment.

Further, the adhesive composition according to another aspect of the present invention is an adhesive composition containing a polyester resin (A4) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. Since the polyester resin (A4) has an acid value of 3 mgKOH / g or more, a temperature of 23 ° C., and a dielectric loss tangent (α) of 0.005 or less at 10 GHz under a relative humidity of 50% RH environment, it has a low dielectric constant. In addition, it has a low dielectric loss tangent, particularly a low dielectric loss tangent, and has an excellent effect of initial adhesiveness after curing and long-term durability in a moist heat environment.

Further, the adhesive composition according to another aspect of the present invention is an adhesive composition containing a polyester resin (A5) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. The polyester resin (A5) has a glass transition temperature (Tg) of -5 ° C or higher, an acid value of 3 mgKOH / g or higher, a temperature of 23 ° C, and a relative humidity of 50%. Since it is .005 or less, it has a low dielectric constant and a low dielectric loss tangent, particularly a low dielectric loss tangent, and has an excellent effect of initial adhesiveness after curing and long-term durability in a moist heat environment.

Further, the adhesive composition according to another aspect of the present invention is an adhesive composition containing a polyester resin (A6) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. Since the polyester resin (A6) has a dielectric loss tangent (α) of 0.003 or less at 10 GHz under a temperature of 23 ° C. and a relative humidity of 50% RH, low dielectric constant and low dielectric loss tangent, particularly It has a low dielectric loss tangent, and has an excellent effect of initial adhesiveness after curing and long-term durability in a moist heat environment.

When the polyepoxy compound (B) is further contained, an adhesive layer having excellent heat resistance and not only adhesive strength but also solder heat resistance can be obtained.

Further, when the content of the polyester resin (A1) in the polyester resin is more than 50% by weight, it becomes more excellent in low hygroscopicity and long-term durability in a moist heat environment.

The adhesive composition of the present invention is particularly used for producing an adhesive for producing a metal-plastic laminate, for example, a flexible laminate such as a flexible copper-clad laminate or a flexible printed circuit board, a coverlay, or a bonding sheet. It is preferably used as an adhesive to be used, and more preferably as an adhesive for a flexible printed wiring board. Further, since the adhesive composition of the present invention and the obtained adhesive have the above-mentioned excellent effects, the flexible printed wiring board using such an adhesive has excellent long-term durability and reliability in a moist heat environment. Will be high.

Hereinafter, the configuration of the present invention will be described in detail, but these are examples of desirable embodiments.
In the present invention, the "class" added after the compound name is a concept that includes the derivative of the compound in addition to the compound. For example, the term "carboxylic acids" includes, in addition to carboxylic acids, carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic acid esters.

First, the adhesive composition according to the first aspect of the present invention is characterized by containing a polyester resin (A1) that satisfies the following requirements.
[1] The ester bond concentration is 7 mmol / g or less.
[2] The acid value is 3 mgKOH / g or more.
[3] The glass transition temperature (Tg) is -5 ° C or higher.

Next, the adhesive composition according to the second aspect of the present invention is characterized by containing a polyester resin (A2) that satisfies the following requirements.
[I] The above-mentioned multivalent carboxylic acids contain 25 mol% or more of aromatic polyvalent carboxylic acids.
[II] The above-mentioned multivalent carboxylic acids contain trivalent or higher valent carboxylic acids (x1) having an acid anhydride radix of 0 or 1.
[III] The ester bond concentration is 7 mmol / g or less.
[IV] The acid value is 3 mgKOH / g or more.

Further, the adhesive composition according to the third aspect of the present invention is characterized by containing the polyester resin according to any one of the following (1) to (4).
(1) A polyester resin (A3) having a glass transition temperature (Tg) of −5 ° C. or higher, a temperature of 23 ° C., and a dielectric loss tangent (α) of 0.005 or lower at 10 GHz under a relative humidity of 50% RH environment.
(2) A polyester resin (A4) having an acid value of 3 mgKOH / g or more, a temperature of 23 ° C., and a dielectric loss tangent (α) of 0.005 or less at 10 GHz under a relative humidity of 50% RH environment.
(3) Polyester resin having a glass transition temperature (Tg) of -5 ° C or higher, an acid value of 3 mgKOH / g or higher, a temperature of 23 ° C, and a dielectric loss tangent (α) of 0.005 or lower at 10 GHz under a relative humidity of 50% RH environment. (A5).
(4) A polyester resin (A6) having a dielectric loss tangent (α) of 0.003 or less at 10 GHz under a temperature of 23 ° C. and a relative humidity of 50% RH.
Hereinafter, the first to third aspects will be described in order.

<< First aspect >>
The adhesive composition of the present invention contains at least a polyester resin (A1) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols. First, the polyester resin (A1) will be described.

<Polyester resin (A1)>
The polyester resin (A1) contains a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and preferably an ester bond between the polyvalent carboxylic acid and the polyhydric alcohol. It is obtained by letting.

[Multivalent carboxylic acids]
Examples of the polyvalent carboxylic acid in the polyvalent carboxylic acids include aromatic polyvalent carboxylic acids described later; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their acid anhydrides. Alicyclic polyvalent carboxylic acids such as substances; Examples thereof include aliphatic polyvalent carboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid. One or more polyvalent carboxylic acids can be used.

It is preferable to contain aromatic polyvalent carboxylic acids as the polyvalent carboxylic acids. Examples of aromatic polyvalent carboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid, and derivatives thereof (aromatic dicarboxylic acids). In addition, aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid can be mentioned. Further, the above-mentioned aromatic polyvalent carboxylic acids also include trifunctional or higher functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and acid value to the polyester resin (A1). Examples of the aromatic carboxylic acid in trifunctional or higher functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethyleneglucolbis (anhydrotrimeritate), glycerol tris (anhydrotrimeritate), and trimellitic acid anhydride. Trimellitic acid dianhydride, oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride , 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 2,2'-bis [(dicarboxyphenoxy) phenyl ] Propane dianhydride and the like can be mentioned.
Among these, aromatic dicarboxylic acids are preferable, terephthalic acid and isophthalic acid are particularly preferable, and isophthalic acid is more preferable.

The content of the aromatic polyvalent carboxylic acids with respect to the total polyvalent carboxylic acids is preferably 25 mol% or more, more preferably 40 mol% or more, particularly preferably 70 mol% or more, still more preferably 90 mol% or more. Is. Aromatic polyvalent carboxylic acids may account for 100 mol%. If the content of aromatic carboxylic acids is too low, the long-term durability in a moist heat environment tends to be insufficient.

The content (molar ratio) of aromatic polyvalent carboxylic acids with respect to the total polyvalent carboxylic acids can be calculated from the following formula.
Aromatic acid content (mol%) = (aromatic polyvalent carboxylic acid (mol) / polyvalent carboxylic acid (mol)) × 100

Aromatic dicarboxylic acids having sulfonic acid groups such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5 (4-sulfophenoxy) isophthalic acid. , And the aromatic dicarboxylic acid salt having a sulfonic acid base such as a metal salt or an ammonium salt thereof has a content of 10 mol% or less based on the total polyvalent carboxylic acid from the viewpoint of hygroscopicity of the polyester resin (A1). It is preferably 5 mol% or less, particularly preferably 3 mol% or less, still more preferably 1 mol% or less, and most preferably 0 mol% or less.

[Multivalent alcohols]
Examples of polyhydric alcohols include bisphenol skeleton-containing monomers, aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, and aromatic polyhydric alcohols. One type or two or more types of polyhydric alcohols can be used.

Examples of the bisphenol skeleton-containing monomer include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, and bisphenol fluorene. Examples thereof include hydrogenated products thereof, ethylene oxide adducts obtained by adding 1 to several mols of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols, glycols such as propylene oxide adducts, and the like. Among them, those containing a bisphenol A skeleton are preferable, ethylene oxide adducts are preferable from the viewpoint of reactivity, and 2-3 mol of ethylene oxide is added from the viewpoint of heat resistance, low hygroscopicity, and long-term durability in a moist heat environment. The thing is preferable.

The content of the bisphenol skeleton-containing monomer in the whole polyhydric alcohols is preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 30 mol% or more, still more preferably 40 mol% or more. .. If the content of the bisphenol skeleton-containing monomer is too small, the hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.
The upper limit of the content of the bisphenol skeleton-containing monomer with respect to the total polyhydric alcohols is 100 mol%.

Examples of the aliphatic polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and 1,5-pentane. Diol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, dimethylol heptane, 2,2,4 -Trimethyl-1,3-pentanediol and the like can be mentioned.

Examples of the alicyclic polyhydric alcohol include 1,4-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.

Examples of the aromatic polyhydric alcohol include paraxylene glycol, metaxylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, and ethylene oxide adduct of 1,4-phenylene glycol.

In addition, diethylene glycol, triethylene glycol, dipropylene glycol, and ether bond-containing glycols other than bisphenol skeleton-containing monomers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol have heat resistance, low moisture absorption, and moist heat. From the viewpoint of long-term durability in the environment, the content of the polyester resin as a whole is preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, still more preferably 8% by weight. % Or less, most preferably 5% by weight or less.

[General raw material compounds constituting the polyester resin (A1)]
The compound constituting the polyester resin (A1) may contain dimer acids as polyhydric carboxylic acids, and dimer diols may be contained as polyhydric alcohols regardless of whether or not dimer acids are contained. It may be contained.
In the present invention, the compound constituting the polyester resin (A1) preferably contains at least one selected from the group consisting of dimer acids as polyhydric carboxylic acids and dimer diols as polyhydric alcohols.
Examples of dimer acids and dimer diols include dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like (mainly those having 36 to 44 carbon atoms) and dimers which are reduced products thereof. Examples thereof include diols and their hydrogenated additives. Of these, hydrogenated additives are preferable from the viewpoint of suppressing gelation during production, and dimerdiols are preferable, and hydrogenated dimers are particularly preferable, from the viewpoint of increasing the content ratio of aromatic acids of polyvalent carboxylic acids. It is a diol.

The total content (α + β) (mol%) of the dimer acids content (α) with respect to the total polyhydric carboxylic acids and the dimer diol content (β) with respect to the total polyhydric alcohols is 5 mol% or more. It is preferable, more preferably 10 mol% or more, particularly preferably 15 mol% or more, still more preferably 20 mol% or more. The total content (α + β) (mol%) is preferably 100 mol% or less, more preferably 80 mol% or less, particularly preferably 65 mol% or less, still more preferably 55 mol% or less.
If the total content (α + β) (mol%) of dimer acids and dimer diols is too small, the long-term durability in a low hygroscopicity and moist heat environment tends to be insufficient, and the total content (α + β) ( If it is too much (molar%), the tack-free property before curing and the initial adhesiveness after curing tend to be insufficient.

The ratio ((β) / (α + β) (molar ratio)) of the content (β) of dimer diols to the total content (α + β) of dimer acids and dimer diols must be 0.6 or more. It is preferably 0.7 or more, particularly preferably 0.8 or more, still more preferably 0.9 or more, and most preferably 1.

If the content (β) of dimerdiols is too small relative to the total content (α + β) of dimer acids and dimerdiols, the long-term durability in a moist heat environment tends to be insufficient.

The total content (α + β) (% by weight) of the content (α) of dimer acids and the content (β) of dimer diols with respect to the entire polyester resin (A1) is preferably 10% by weight or more, more preferably. Is 15% by weight or more, particularly preferably 20% by weight or more, further preferably 30% by weight or more, and the total content (α + β) (% by weight) is preferably 80% by weight or less, more preferably. It is 70% by weight or less, particularly preferably 60% by weight or less, and further preferably 50% by weight or less.

If the total content (α + β) (% by weight) of dimer acids and dimer diols is too small, the long-term durability in a low hygroscopicity and moist heat environment tends to be insufficient, and the total content (α + β) ( If it is too much (% by weight), the tack-free property before curing and the adhesiveness after curing tend to be insufficient.

Further, an oxycarboxylic acid compound having a hydroxyl group and a carboxy group in its molecular structure can also be used as a raw material compound for the polyester resin (A1). Examples of such oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis ( p-Hydroxyphenyl) Valeric acid and the like can be mentioned.

In the polyester resin (A1) used in the present invention, in addition to the polyvalent carboxylic acid anhydride described later, trifunctional or higher functional polyvalent carboxylic acids and trifunctional or higher functional acids for the purpose of introducing a branched skeleton as needed. At least one selected from the group consisting of trifunctional or higher functional polyhydric alcohols may be copolymerized. In particular, when a cured coating film is obtained by reacting with a curing agent, the introduction of a branched skeleton increases the terminal group concentration (reaction point) of the resin, and a strong coating film having a high crosslink density can be obtained.

Examples of the trifunctional or higher functional polyvalent carboxylic acids include trimellitic acid, trimesic acid, ethyleneglucolbis (anhydrotrimerite), glycerol tris (anhydrotrimerite), and trimellitic anhydride. Pyromellitic acid dianhydride, oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride, 3 , 3', 4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 2,2'-bis [(dicarboxyphenoxy) phenyl] propane Examples thereof include compounds such as dianhydride. Examples of the trifunctional or higher functional alcohols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like.
As the trifunctional or higher functional polyvalent carboxylic acids and the trifunctional or higher functional alcohols, one kind or two or more kinds can be used, respectively.

When at least one selected from the group consisting of a trifunctional or higher-functional polyvalent carboxylic acid and a trifunctional or higher-functional polyhydric alcohol is used separately from the polyvalent carboxylic acid anhydride described later, the entire polyvalent carboxylic acid is used. The content of the trifunctional or higher polyvalent carboxylic acid with respect to the above, or the content of the trifunctional or higher polyhydric alcohol with respect to the whole polyhydric alcohol is preferably 0.1 to 5 mol%, more preferably 0.1, respectively. It is in the range of ~ 3 mol%. If the content of both or one of them is too large, the mechanical properties such as the elongation at break point of the coating film formed by the application of the adhesive tend to decrease, and gelation tends to occur during the polymerization. ..

The polyester resin (A1) in the present invention preferably has a carboxy group in the side chain in terms of curing speed and heat resistance after curing. Such a polyester-based resin (A1) contains a polyvalent carboxylic acid anhydride having a carboxylic acid anhydride structure as a polyvalent carboxylic acid (hereinafter, may be simply referred to as "polyvalent carboxylic acid anhydride"). It is obtained by copolymerizing the copolymerization component.

The polyvalent carboxylic acid anhydride preferably has at least two carboxylic acid anhydride structures for the purpose of introducing a carboxy group into the side chain, for example, 1,2,4,5-benzenetetracarboxylic acid. Dianoxide (pyromellitic acid dianhydride), 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride, 4,4-oxydiphthalic acid dianhydride, 2,3,6,7-naphthalenetetra Carboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, ethylene glycol bistrimerite dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride, 2 , 2', 3,3'-diphenylsulfonetetracarboxylic acid anhydride, thiophene-2,3,4,5-tetracarboxylic acid dianhydride and other aromatic polyvalent carboxylic acid anhydrides;
1,2,3,4-cyclobutanetetracarboxylic acid anhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 5- (2) , 5-Dioxotetrahydrofuryl) -3-cyclohexene-1,2-dicarboxylic acid anhydride, cyclopentanetetracarboxylic acid dianhydride and other alicyclic polyvalent carboxylic acid anhydrides;
Aliphatic polyvalent carboxylic acid anhydrides such as ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride;
And so on. One type selected from these can be used alone, or two or more types can be used in combination.

Among these polyvalent carboxylic acid anhydrides, the polymerization reactivity at the time of producing the polyester resin (A1), the heat resistance of the produced polyester resin (A1), and the long-term durability in a moist heat environment are considered. Therefore, it is preferably an aromatic polyvalent carboxylic acid anhydride, and more preferably 1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride), 2,3,6,7-. Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,3', 4,4'-diphenyltetracarboxylic dianhydride, and particularly preferably 1,2. , 4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride).

The content of the polyvalent carboxylic acid anhydride in the polyvalent carboxylic acids is preferably 0.5 to 20 mol%, more preferably 1 to 15 mol%, and particularly preferably 2 with respect to the total polyvalent carboxylic acids. It is -10 mol%, more preferably 3-8 mol%. If the content is too small, the heat resistance tends to be insufficient, and if the content is too large, it may gel during the manufacturing process of the polyester resin (A1), or may have low hygroscopicity or in a moist heat environment. Long-term durability tends to be inadequate.

[Manufacturing of polyester resin (A1)]
The polyester resin (A1) used in the present invention can be produced by a well-known method. For example, polyhydric carboxylic acids and polyhydric alcohols are subjected to an esterification reaction in the presence of a catalyst, if necessary. This can be produced by obtaining a polyester-based resin and further introducing an acid value.

Examples of the method for introducing an acid value into a polyester resin include a method for introducing a carboxylic acid into a resin by acid addition after an esterification reaction or polycondensation under reduced pressure. When a monocarboxylic acid, a dicarboxylic acid, or a polyfunctional carboxylic acid compound is used for acid addition, the molecular weight may decrease due to ester exchange, and it is preferable to use a compound having at least one carboxylic acid anhydride. Examples of the acid anhydride include succinic anhydride, maleic anhydride, orthophthalic anhydride, 2,5-norbornenedicarboxylic acid anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, and oxydiphthal. Acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride, 3,3', 4,4' -Diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 2,2'-bis [(dicarboxyphenoxy) phenyl] propane dianhydride and other compounds Can be mentioned.

When the total polyvalent carboxylic acids constituting the polyester resin (A1) are 100 mol%, if 15 mol% or more of the acid is added, gelation may occur, and polyester depolymerization may occur. The molecular weight may decrease. Examples of the acid addition method include a method of directly adding in a bulk state and a method of adding polyester as a solution. The reaction in the bulk state is fast, but if a large amount is added, gelation may occur and the reaction is carried out at a high temperature. Therefore, care must be taken such as blocking oxygen gas to prevent oxidation. On the other hand, the addition in the solution state has a slow reaction, but a large amount of carboxy groups can be stably introduced.

Further, when obtaining a polyester resin having a carboxy group in the side chain, a hydroxyl group-containing prepolymer obtained by copolymerizing polyvalent carboxylic acids excluding polyvalent carboxylic acid anhydride and polyhydric alcohols is polyvalent. The method of reacting the carboxylic acid anhydride is preferable in terms of productivity.

[Ester bond concentration of polyester resin (A1)]
The ester bond concentration of the polyester resin (A1) used in the present invention is 7 mmol / g or less, preferably 2 to 6.5 mmol / g, more preferably 2.5 to 6 mmol / g, and particularly preferably. It is 3 to 5.5 mmol / g, more preferably 3.1 to 5 mmol / g.
If the ester bond concentration is too high, the hygroscopicity and long-term durability in a moist heat environment will be insufficient. Further, if the ester bond concentration is too low, the initial adhesiveness becomes insufficient.

The definition and measurement method of the ester bond concentration are as follows.
The ester bond concentration (mmol / g) is the number of moles of ester bonds in 1 g of the polyester resin, and is obtained by, for example, a calculated value from the charged amount. Such a calculation method is a value obtained by dividing the number of moles of the smaller amount of each of the charged amounts of the polyvalent carboxylic acids and the polyhydric alcohols by the total weight of the resin, and an example of the calculation formula is shown below.
When the amounts of the polyvalent carboxylic acids and the polyhydric alcohols charged are the same molar amount, either of the following calculation formulas may be used.
Further, when a monomer having both a carboxy group and a hydroxyl group is used as a monomer, or when polyester is produced from caprolactone or the like, the calculation method is appropriately changed.

(When there are less multivalent carboxylic acids than polyhydric alcohols)
Ester group concentration (mmol / g) = [(A1 / a1 × m1 + A2 / a2 × m2 + A3 / a3 × m3 ...) / Z] × 1000
A: Amount of polyvalent carboxylic acids charged (g)
a: Molecular weight of polyvalent carboxylic acids m: Number of carboxylic acid groups per molecule of polyvalent carboxylic acids Z: Finished weight (g)

(When there are fewer polyhydric alcohols than polyhydric carboxylic acids)
Ester group concentration (mmol / g) = [(B1 / b1 × n1 + B2 / b2 × n2 + B3 / b3 × n3 ...) / Z] × 1000
B: Amount of polyhydric alcohol charged (g)
b: Molecular weight of polyhydric alcohols n: Number of hydroxyl groups per molecule of polyhydric alcohols Z: Finished weight (g)

The ester bond concentration can also be measured by a known method using NMR or the like.

Further, the concentration of other polar groups other than the ester bond and the reactive functional group is preferably low from the viewpoint of low hygroscopicity and long-term durability in a moist heat environment.
Examples of other polar groups include an amide group, an imide group, a urethane group, a urea group, an ether group, a carbonate group and the like.

The total concentration of the amide group, the imide group, the urethane group and the urea group is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1 mmol / g or less, still more preferably. Is 0.5 mmol / g or less, most preferably 0.2 mmol / g or less.
Examples of the ether group include an alkyl ether group and a phenyl ether group, and it is particularly preferable to reduce the concentration of the alkyl ether group from the viewpoint of low hygroscopicity and long-term durability in a moist heat environment.
The alkyl ether group concentration is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1.5 mmol / g or less, still more preferably 1 mmol / g or less, and most It is preferably 0.5 mmol / g or less. The phenyl ether group concentration is preferably 5 mmol / g or less, more preferably 4 mmol / g or less, particularly preferably 3 mmol / g or less, still more preferably 2.5 mmol / g or less. ..
The carbonate group concentration is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, particularly preferably 1 mmol / g or less, still more preferably 0.5 mmol / g or less, and most preferably. Is 0.2 mmol / g or less.

[Acid value of polyester resin (A1)]
The acid value of the polyester resin (A1) used in the present invention is 3 mgKOH / g or more, preferably 4 to 60 mgKOH / g, more preferably 5 to 40 mgKOH / g, particularly preferably 6 to 30 mgKOH / g, still more preferably. It is 7 to 20 mgKOH / g.
If the acid value is too low, when the adhesive composition contains the polyepoxy compound (B), the cross-linking points with the poly-epoxy compound (B) will be insufficient and the degree of cross-linking will be low, resulting in poor heat resistance. It will be enough. Further, if the acid value is too high, the hygroscopicity and long-term durability in a moist heat environment are lowered, and a large amount of polyepoxy compound (B) is required at the time of curing. It tends to be inferior in the reduced dielectric properties.

The definition and measurement method of acid value are as follows.
The acid value (mgKOH / g) can be determined by dissolving 1 g of a polyester resin in 30 g of a mixed solvent of toluene / methanol (for example, toluene / methanol = 7/3 by volume) and neutralizing titration based on JIS K0070. it can.
In the present invention, the acid value of the polyester resin (A1) is due to the content of carboxy groups in the resin.

[Glass transition temperature (Tg) of polyester resin (A1)]
The glass transition temperature (Tg) of the polyester resin (A1) used in the present invention is −5 ° C. or higher, preferably 0 to 100 ° C., more preferably 3 to 80 ° C., particularly preferably 5 to 60 ° C., and further. The temperature is preferably 7 to 40 ° C, most preferably 10 to 30 ° C.
If the glass transition temperature (Tg) is too low, the initial adhesiveness and tack-free property become insufficient. Further, if the glass transition temperature (Tg) is too high, the initial adhesiveness and flexibility tend to be insufficient.

The method for measuring the glass transition temperature (Tg) is as follows.
The glass transition temperature (Tg) can be determined by measuring with a differential scanning calorimeter. The measurement conditions are a measurement temperature range of −70 to 140 ° C. and a temperature rise rate of 10 ° C./min.

[Peak top molecular weight (Mp) and weight average molecular weight (Mw) of polyester resin (A1)]
The peak top molecular weight (Mp) of the polyester resin (A1) used in the present invention is preferably 5000 to 150,000, more preferably 10,000 to 100,000, particularly preferably 15,000 to 70,000, and even more preferably 25,000 to 40,000.
If the peak top molecular weight (Mp) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the peak top molecular weight (Mp) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

The weight average molecular weight (Mw) of the polyester resin (A1) used in the present invention is preferably 5000 to 300,000, more preferably 10,000 to 200,000, particularly preferably 20,000 to 150,000, and even more preferably 30,000 to 100,000.
If the weight average molecular weight (Mw) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminated boards such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the weight average molecular weight (Mw) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

The method for measuring the peak top molecular weight (Mp) and the weight average molecular weight (Mw) is as follows.
Peak top molecular weight (Mp) and weight average molecular weight (Mw), high performance liquid chromatography (manufactured by Tosoh Corporation, "HLC-8320GPC") by column (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 ^6, theory The number of stages: 16000 stages / piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm)) can be measured using two series, and can be determined by standard polystyrene molecular weight conversion.

[Water absorption rate (% by weight) of polyester resin (A1)]
The water absorption rate of the polyester resin (A1) used in the present invention is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, still more preferably 0.6% by weight or less. is there.
If the water absorption rate is too high, the moist heat durability and insulation reliability tend to deteriorate, and the dielectric properties tend to be inferior. Inferior in dielectric properties means that the values of the relative permittivity and the dielectric loss tangent do not decrease or increase.

The method for measuring the water absorption rate is as follows.
A polyester resin solution (before blending the polyepoxy compound (B)) was applied onto a release film with an applicator and dried at 120 ° C. for 10 minutes to prepare a sheet having a dry film thickness of the polyester resin layer of 65 μm. This sheet was cut into a size of 7.5 cm × 11 cm, the polyester resin layer surface of the sheet was laminated on a glass plate, and then the release film was peeled off. By repeating this operation 6 times, a test plate having a polyester resin layer having a thickness of 390 μm on the glass plate is obtained.
The test plate thus obtained is immersed in purified water at 23 ° C. for 24 hours, then taken out, the surface of the test plate is wiped off, and the test plate is dried at 70 ° C. for 2 hours. The weight required in each of these steps is measured, and the water absorption rate (% by weight) is calculated from the weight change according to the following formula.
(Cd) × 100 / (ba)
a: Weight of the glass plate alone b: Weight of the initial test plate c: Weight of the test plate immediately after being taken out from purified water and wiped off d: Weight of the test plate after drying at 70 ° C. for 2 hours

The content of the polyester resin (A1) in the polyester resin in the adhesive composition of the present invention is preferably more than 50% by weight, more preferably 70% by weight, based on the total polyester resin. As mentioned above, it is particularly preferably 85% by weight or more. If the content is too small, the hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.

<Polyepoxy compound (B)>
The adhesive composition of the present invention preferably further contains the polyepoxy compound (B). By reacting the epoxy group in the polyepoxy compound (B) with the carboxy group in the polyester resin (A1) and curing it, an adhesive layer with excellent heat resistance and not only adhesive strength but also solder heat resistance can be obtained. Obtainable.

Examples of the polyepoxide compound (B) used in the present invention include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; phenol novolac glycidyl ether and cresol novolac. Polyfunctional glycidyl ether type such as glycidyl ether; glycidyl ester type such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; triglycidyl isocyanurate, 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, epoxidized soybean oil Such as alicyclic or aliphatic epoxides and the like. As the polyepoxy compound (B), one kind or two or more kinds can be used.

When the adhesive composition of the present invention contains a nitrogen atom-containing polyepoxy compound (nitrogen atom-containing polyepoxy compound) as the polyepoxy compound (B), the adhesive composition is heated at a relatively low temperature. There is a tendency that the coating film of an object can be B-staged (semi-cured state), and the fluidity of the B-stage film can be suppressed to improve workability in the bonding operation. Further, the effect of suppressing the foaming of the B stage film can be expected, which is preferable.

Examples of the nitrogen atom-containing polyepoxy compound include glycidyl amines such as tetraglycidyl diaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethylcyclohexanone, N, N, N', and N'-tetraglycidyl-m-xylene diamine. The system etc. can be mentioned.

When the adhesive composition of the present invention contains the polyepoxy compound (B) and the polyepoxy compound (B) further contains these nitrogen atom-containing polyepoxy compounds, the nitrogen atom-containing polyepoxy compound The content of the polyepoxy compound (B) is preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less based on the whole polyepoxy compound (B).
The content of the nitrogen atom-containing polyepoxy compound is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight, based on 100 parts by weight of the polyester resin (A1). It is less than a part by weight.
If the content of the nitrogen atom-containing polyepoxy compound is too large, the rigidity tends to be excessively high and the adhesiveness tends to decrease, and the cross-linking reaction tends to proceed during the storage of the adhesive sheet, resulting in a decrease in sheet life. Tend to do.

The equivalent of the epoxy group to the carboxy group is preferably 0.8 to 5, more preferably 0.9 to 3, particularly preferably 1 to 2.5, and even more preferably 1.2 to 2.
If the corresponding amount is too large, the initial adhesiveness and low hygroscopicity tend to be insufficient, and the dielectric properties tend to be inferior. On the other hand, if it is too small, the long-term durability and solder heat resistance in a moist heat environment tend to be insufficient.

The equivalent of the epoxy group to the carboxy group (COOH) is calculated by the following formula from the acid value of the polyester resin (A1) and the epoxy equivalent (g / eq) of the blended polyepoxy compound (B).
Epoxy equivalent to COOH = (a ÷ WPE) / (AV ÷ 56.1 ÷ 1000 × b)
a: Weight (g) of the polyepoxy compound (B) used in the formulation
WPE: Epoxy equivalent (g / eq) of polyepoxy compound (B)
AV: Acid value of polyester resin (A1) (mgKOH / g)
b: Weight (g) of the polyester resin (A1) used for compounding

<Adhesive composition>
The adhesive composition of the present invention contains at least a polyester resin (A1), preferably a polyepoxy compound (B), has low hygroscopicity, tack-free property before curing, and initial stage after curing. It has the effect of being excellent in adhesiveness and long-term durability in a moist heat environment.

In the adhesive composition of the present invention, a filler, a flame retardant, or the like may be blended. In that case, the content of the polyester resin (A1) in the adhesive composition should be such that the filler, the flame retardant, or the like is blended. In consideration of, it is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, still more preferably 60 to 85% by weight, based on the total solid content.

When the adhesive composition of the present invention contains the polyepoxy compound (B), the content of the polyepoxy compound (B) is preferably 1 with respect to 100 parts by weight of the polyester resin (A1). It is ~ 30 parts by weight, more preferably 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight, still more preferably 4 to 10 parts by weight. If the content of the polyepoxy compound (B) is too small, the heat resistance and long-term durability in a moist heat environment tend to be insufficient, and if it is too large, the initial adhesiveness and low hygroscopicity may be insufficient. , The dielectric properties tend to be inferior.

The adhesive composition of the present invention may contain a solvent in order to appropriately adjust the viscosity of the adhesive composition and facilitate handling when forming a coating film. The solvent is used to ensure handleability and workability in molding the adhesive composition, and the amount used is not particularly limited.

Examples of the solvent include ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate; ethers such as ethylene glycol monomethyl ether; N, N-dimethylformamide, N, N- Amides such as dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; aromatics such as toluene and xylene can be mentioned. The above-mentioned solvents may be used alone or in admixture of two or more in any combination and ratio.

[Other ingredients]
The adhesive composition of the present invention may contain other components other than those listed above for the purpose of further improving its functionality. Other components include, for example, coupling agents such as inorganic fillers and silane coupling agents, ultraviolet inhibitors, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, low elasticity agents, and dilutions. Examples include agents, defoaming agents, ion trapping agents, leveling agents, catalysts and the like.
When the adhesive composition of the present invention contains other components, the content of the other components is preferably 70% by weight or less, more preferably 0.05 to 60% by weight, and particularly preferably 0.1 to 50% by weight. By weight%, more preferably 0.2 to 40% by weight.

<Adhesive>
The adhesive of the present invention is obtained by curing the above-mentioned adhesive composition, and has the effects of excellent initial adhesiveness, low hygroscopicity, and long-term durability in a moist heat environment.
"Curing" in the present invention means that the adhesive composition is intentionally cured by heat and / or light, and the degree of curing can be controlled according to desired physical properties and applications. The degree of curing can be confirmed by the gel fraction of the adhesive, and the gel fraction is preferably 50% or more, more preferably 60% or more, particularly preferably 70% or more, still more preferably 75% or more. If the gel fraction is too low, the heat resistance and long-term durability in a moist heat environment tend to be insufficient.
The above gel fraction means the weight percentage of the insoluble adhesive component with respect to the weight of the adhesive before immersion in which the adhesive is immersed in methyl ethyl ketone at 23 ° C. for 24 hours.

The method for curing the adhesive composition when the adhesive composition of the present invention is cured or semi-cured to obtain an adhesive varies depending on the blending components and the blending amount in the adhesive composition, but is usually 80 to 200 ° C. The heating conditions for 10 minutes to 10 hours can be mentioned.

A catalyst may be used when curing the adhesive composition of the present invention using the polyepoxy compound (B).
Such catalysts include, for example, 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methyl. Imidazole compounds such as imidazole; triethylamine, triethylenediamine, N'-methyl-N- (2-dimethylaminoethyl) piperazine, 1,8-diazabicyclo (5,4,0) -undecene-7,1,5-diazabicyclo Tertiary amines such as (4,3,0) -nonen-5,6-dibutylamino-1,8-diazabicyclo (5,4,5) -undecene-7; and these tertiary amines as phenol or Compounds made into amine salts with octylic acid, quaternized tetraphenylborate salt and the like; cationic catalysts such as triarylsulfonium hexafluoroantimonate and diallyliodonium hexafluoroantimonate; triphenylphosphine and the like can be mentioned. Of these, 1,8-diazabicyclo (5,4,0) -undecene-7 and 1,5-diazabicyclo (4,5,3,0) -nonene-5,6-dibutylamino-1,8-diazabicyclo (5) , 4,0) -tertiary amines such as undecene-7; and compounds obtained by converting these tertiary amines into amine salts with phenol, octyl acid, quaternized tetraphenylborate salt, etc. are thermosetting and heat resistant. It is preferable in terms of property, adhesion to metal, and storage stability after compounding.
At that time, the blending amount is preferably 0.01 to 1 part by weight with respect to 100 parts by weight of the polyester resin (A1). Within this range, the catalytic effect on the reaction between the polyester resin (A1) and the polyepoxy compound (B) is further increased, and strong adhesive performance can be obtained.

[Use]
Since the adhesive of the present invention is excellent in initial adhesiveness, low moisture absorption, and long-term durability in a moist heat environment, it is effective for adhering a base material made of various materials such as resin and metal, particularly with a metal layer. It is suitable as an adhesive for producing a laminated plate with a plastic layer, for example, an adhesive used for bonding electronic material members.
Examples of the "electronic material member" in the present invention include a flexible printed circuit board, a coverlay, a bonding sheet, and the like.
Examples of those manufactured by laminating electronic material members include flexible laminated boards such as flexible copper-clad laminated boards and flexible printed circuit boards. The flexible laminated board is, for example, a laminated body in which "flexible flexible substrate / adhesive layer / conductive metal layer made of copper, aluminum, alloys of these, etc." is sequentially laminated, and constitutes an adhesive layer. The adhesive of the present invention can be used as the adhesive. The flexible laminated plate may further include another insulating layer, another adhesive layer, and another conductive metal layer in addition to the above-mentioned various layers.

<< Second aspect >>
The adhesive composition of the present invention contains at least a polyester resin (A2) containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin (A2) will be described.

<Polyester resin (A2)>
The polyester resin (A2) contains a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and preferably an ester bond between the polyvalent carboxylic acid and the polyhydric alcohol. It is obtained by letting.

[Multivalent carboxylic acids]
Examples of the polyvalent carboxylic acid in the polyvalent carboxylic acid include an aromatic polyvalent carboxylic acid described later; a trivalent or higher-valent polyvalent carboxylic acid (x1) having an acid anhydride group number of 0 or 1 described later; 1,4. -Alicyclic polyvalent carboxylic acids such as cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and its acid anhydrides; succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedic acid And other aliphatic polyvalent carboxylic acids can be mentioned. One or more polyvalent carboxylic acids can be used.

The multivalent carboxylic acids include aromatic polyvalent carboxylic acids. Examples of aromatic polyvalent carboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and biphenyldicarboxylic acid, and derivatives thereof (aromatic dicarboxylic acids). In addition, aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid can be mentioned. Further, the above-mentioned aromatic polyvalent carboxylic acids also include trifunctional or higher functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and acid value to the polyester resin (A2). Examples of the aromatic carboxylic acid in trifunctional or higher functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethyleneglucolbis (anhydrotrimeritate), glycerol tris (anhydrotrimeritate), and trimellitic acid anhydride. Trimellitic acid dianhydride, oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride , 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 2,2'-bis [(dicarboxyphenoxy) phenyl ] Propane dianhydride and the like can be mentioned.
Among these, aromatic dicarboxylic acids are preferable, terephthalic acid and isophthalic acid are particularly preferable, and isophthalic acid is more preferable.

The content of aromatic polyvalent carboxylic acids with respect to the total polyvalent carboxylic acids is 25 mol% or more, preferably 40 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more. Aromatic polyvalent carboxylic acids may account for 100 mol%. If the content of aromatic carboxylic acids is too low, the long-term durability in a moist heat environment will be insufficient.

The polyvalent carboxylic acids also contain trivalent or higher valent carboxylic acids (x1) having an acid anhydride radix of 0 or 1. The valence of the carboxy group in the polyvalent carboxylic acid (x1) is preferably 3 to 6 valent, more preferably 3 to 4 valent. Examples of such polyvalent carboxylic acids (x1) include those having an acid anhydride group number of 0 or 1 among the above-mentioned trifunctional or higher functional aromatic carboxylic acids. For example, trimellitic acid anhydride, trimellitic acid, trimesic acid and the like can be mentioned. Among these, those having an acid anhydride group number of 1 are preferable, and trimellitic acid anhydride is particularly preferable.
Examples of the polyvalent carboxylic acids (x1) other than aromatic carboxylic acids include hydrogenated trimellitic acid anhydride and the like.

Aromatic dicarboxylic acids having sulfonic acid groups such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5 (4-sulfophenoxy) isophthalic acid. , And the aromatic dicarboxylic acid salt having a sulfonic acid base such as a metal salt or an ammonium salt thereof has a content of 10 mol% or less based on the total polyvalent carboxylic acid from the viewpoint of hygroscopicity of the polyester resin (A2). It is preferably 5 mol% or less, particularly preferably 3 mol% or less, still more preferably 1 mol% or less, and most preferably 0 mol% or less.

[Multivalent alcohols]
The polyhydric alcohols are the same as the contents of [polyhydric alcohols] described in the first aspect above. That is, for example, a bisphenol skeleton-containing monomer, an aliphatic polyhydric alcohol, an alicyclic polyhydric alcohol, and an aromatic polyhydric alcohol can be mentioned. One type or two or more types of polyhydric alcohols can be used.

[General raw material compounds constituting the polyester resin (A2)]
The compound constituting the polyester resin (A2) may contain dimer acids as polyhydric carboxylic acids, and dimer diols may be contained as polyhydric alcohols regardless of whether or not dimer acids are contained. It may be contained.
The dimer acids and dimer diols are the same as those of the dimer acids and dimer diols described in the first aspect. That is, in the present invention, the compound constituting the polyester resin (A2) preferably contains at least one selected from the group consisting of dimer acids as polyhydric carboxylic acids and dimer diols as polyhydric alcohols. ..
Examples of dimer acids and dimer diols include dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like (mainly those having 36 to 44 carbon atoms) and dimers which are reduced products thereof. Examples thereof include diols and their hydrogenated additives. Of these, hydrogenated additives are preferable from the viewpoint of suppressing gelation during production, and dimerdiols are preferable, and hydrogenated dimers are particularly preferable, from the viewpoint of increasing the content ratio of aromatic acids of polyvalent carboxylic acids. It is a diol.

The total content (α + β) (% by weight) of the content (α) of dimer acids and the content (β) of dimer diols with respect to the entire polyester resin (A2) is preferably 10% by weight or more, more preferably. Is 15% by weight or more, particularly preferably 20% by weight or more, further preferably 30% by weight or more, and the total content (α + β) (% by weight) is preferably 80% by weight or less, more preferably. It is 70% by weight or less, particularly preferably 60% by weight or less, and further preferably 50% by weight or less.

If the total content (α + β) (% by weight) of dimer acids and dimer diols is too small, the long-term durability in a low hygroscopicity and moist heat environment tends to be insufficient, and the total content (α + β) ( If it is too much (% by weight), the adhesiveness tends to be insufficient.

Further, an oxycarboxylic acid compound having a hydroxyl group and a carboxy group in its molecular structure can also be used as a raw material compound for the polyester resin (A2). Examples of such oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis ( p-Hydroxyphenyl) Valeric acid and the like can be mentioned.

The polyester resin (A2) used in the present invention is a trifunctional or higher functional polyvalent carboxylic acid for the purpose of introducing a branched skeleton, in addition to the polyvalent carboxylic acid (x1) used in the depolymerization reaction described later. And at least one selected from the group consisting of trifunctional or higher functional polyhydric alcohols is preferably copolymerized. In particular, when a cured coating film is obtained by reacting with a curing agent, the introduction of a branched skeleton increases the terminal group concentration (reaction point) of the resin, and a strong coating film having a high crosslink density can be obtained.

Apart from the multivalued carboxylic acids (x1) used in the depolymerization reaction described later, it is selected from the group consisting of trifunctional or higher functional polyvalent carboxylic acids and trifunctional or higher functional alcohols for the purpose of introducing a branched skeleton. When at least one is used, the content of the trifunctional or higher polyvalent carboxylic acid with respect to the entire polyhydric carboxylic acid, or the content of the trifunctional or higher polyhydric alcohol with respect to the entire polyhydric alcohol is preferably, respectively. It is in the range of 0.1 to 5 mol%, more preferably 0.3 to 3 mol%, still more preferably 0.5 to 2 mol%. If the content of both or one of them is too large, the mechanical properties such as the elongation at the breaking point of the coating film formed by the application of the adhesive are lowered, and the adhesive strength tends to be lowered, and during the polymerization. It also tends to gel.

[Manufacturing of polyester resin (A2)]
The polyester resin (A2) used in the present invention can be produced by a well-known method. For example, polyhydric carboxylic acids and polyhydric alcohols are subjected to an esterification reaction in the presence of a catalyst, if necessary. After obtaining a prepolymer, polycondensation is carried out, and further depolymerization is carried out to produce the prepolymer.

The temperature in the esterification reaction between the polyvalent carboxylic acids and the polyhydric alcohols is usually 180 to 280 ° C., and the reaction time is usually 60 minutes to 8 hours.

The temperature in polycondensation is usually 220 to 280 ° C., and the reaction time is usually 20 minutes to 4 hours. Further, polycondensation is preferably performed under reduced pressure.

For the depolymerization, it is preferable to use a trivalent or higher valent carboxylic acid (x1) having an acid anhydride radix of 0 or 1. Examples of trivalent or higher valent carboxylic acids (x1) having 0 or 1 acid anhydride groups include compounds such as trimellitic acid, trimellitic acid anhydride, hydrogenated trimellitic acid anhydride, and trimesic acid. Can be mentioned. Preferably, it is a trivalent or higher valent carboxylic acid (x1) having 1 acid anhydride group, and examples thereof include trimellitic acid anhydride and hydrogenated trimellitic acid anhydride, and in particular, trimellitic acid. Anhydride is preferred.
The temperature in the depolymerization is usually 200 to 260 ° C., and the reaction time is usually 10 minutes to 3 hours.

When the total polyvalent carboxylic acids constituting the polyester resin (A2) are 100 mol%, the molecular weight of the resin is significantly reduced when depolymerization is performed using 20 mol% or more of the polyvalent carboxylic acids (x1). Sometimes. Therefore, when the total polyvalent carboxylic acids constituting the polyester resin (A2) are 100 mol%, it is preferable to carry out depolymerization using less than 20 mol% of the polyvalent carboxylic acids (x1), and more preferably. Depolymerization is carried out using 1 to 15 mol%, particularly preferably 2 to 10 mol%, still more preferably 3 to 8 mol% of polyvalent carboxylic acids (x1).

[Ester bond concentration of polyester resin (A2)]
The ester bond concentration of the polyester resin (A2) used in the present invention is the same as the content of the ester bond concentration described in the first aspect. That is, it is 7 mmol / g or less, preferably 2 to 6.5 mmol / g, more preferably 2.5 to 6 mmol / g, particularly preferably 3 to 5.5 mmol / g, still more preferably 3. It is 1 to 5 mmol / g.
If the ester bond concentration is too high, the hygroscopicity and long-term durability in a moist heat environment will be insufficient. Further, if the ester bond concentration is too low, the initial adhesiveness becomes insufficient.

[Acid value of polyester resin (A2)]
The acid value of the polyester resin (A2) used in the present invention is the same as the content of the acid value described in the first aspect. That is, it is 3 mgKOH / g or more, preferably 4 to 60 mgKOH / g, more preferably 5 to 40 mgKOH / g, particularly preferably 6 to 30 mgKOH / g, and further preferably 7 to 20 mgKOH / g.
If the acid value is too low, when the adhesive composition contains the polyepoxy compound (B), the cross-linking points with the poly-epoxy compound (B) will be insufficient and the degree of cross-linking will be low, resulting in poor heat resistance. It will be enough. Further, if the acid value is too high, the hygroscopicity and long-term durability in a moist heat environment are lowered, and a large amount of polyepoxy compound (B) is required at the time of curing, so that it is often required in recent years. It tends to be difficult to obtain the low dielectric properties.

The definition and measurement method of acid value are as follows.
The acid value (mgKOH / g) can be determined by dissolving 1 g of a polyester resin in 30 g of a mixed solvent of toluene / methanol (for example, toluene / methanol = 7/3 by volume) and neutralizing titration based on JIS K0070. it can.
In the present invention, the acid value of the polyester resin (A2) is due to the content of carboxy groups in the resin.

[Glass transition temperature (Tg) of polyester resin (A2)]
The glass transition temperature (Tg) of the polyester resin (A2) used in the present invention is preferably −5 ° C. or higher, more preferably 0 to 100 ° C., particularly preferably 3 to 80 ° C., still more preferably 5 to It is 60 ° C., particularly preferably 7 to 40 ° C., most preferably 10 to 30 ° C.
If the glass transition temperature (Tg) is too low, the initial adhesiveness and tack-free property tend to be insufficient. Further, if the glass transition temperature (Tg) is too high, the initial adhesiveness and flexibility tend to be insufficient.

[Peak top molecular weight (Mp) and weight average molecular weight (Mw) of polyester resin (A2)]
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) of the polyester resin (A2) used in the present invention are the contents of the peak top molecular weight (Mp) and the weight average molecular weight (Mw) according to the first aspect. Is similar to. That is, the peak top molecular weight (Mp) of the polyester resin (A2) is preferably 5000 to 150,000, more preferably 10000 to 100,000, particularly preferably 15,000 to 70,000, and further preferably 25,000 to 40,000.
If the peak top molecular weight (Mp) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the peak top molecular weight (Mp) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

The weight average molecular weight (Mw) of the polyester resin (A2) used in the present invention is preferably 5000 to 300,000, more preferably 10,000 to 200,000, particularly preferably 20,000 to 150,000, and even more preferably 30,000 to 100,000.
If the weight average molecular weight (Mw) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminated boards such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the weight average molecular weight (Mw) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

[Water absorption rate (% by weight) of polyester resin (A2)]
The water absorption rate of the polyester resin (A2) used in the present invention is the same as the content of the water absorption rate described in the first aspect. That is, it is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, still more preferably 0.6% by weight or less.
If the water absorption rate is too high, the moist heat durability and insulation reliability tend to decrease, and the dielectric properties tend to be inferior.

The method for measuring the water absorption rate is as follows.
A polyester resin solution (before blending the polyepoxy compound (B)) was applied onto a release film with an applicator and dried at 120 ° C. for 10 minutes to prepare a sheet having a dry film thickness of the polyester resin layer of 65 μm. This sheet was cut into a size of 7.5 cm × 11 cm, the polyester resin layer surface of the sheet was laminated on a glass plate, and then the release film was peeled off. By repeating this operation 6 times, a test plate having a polyester resin layer having a thickness of 390 μm on the glass plate is obtained.
The test plate thus obtained was immersed in purified water at 23 ° C. for 24 hours, then taken out, the surface of the test plate was wiped off, and dried at 70 ° C. for 2 hours. The weight required in each of these steps is measured, and the water absorption rate (% by weight) is calculated from the weight change according to the following formula.
(Cd) × 100 / (ba)
a: Weight of the glass plate alone b: Weight of the initial test plate c: Weight of the test plate immediately after being taken out from purified water and wiped off d: Weight of the test plate after drying at 70 ° C. for 2 hours

The content of the polyester resin (A2) in the polyester resin in the adhesive composition of the present invention is preferably more than 50% by weight, more preferably 70% by weight, based on the total polyester resin. As mentioned above, it is particularly preferably 85% by weight or more. If the content is too small, the hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.

<Polyepoxy compound (B)>
The adhesive composition of the present invention preferably further contains the polyepoxy compound (B). Since the polyepoxy compound (B) used in the present invention is the same as the content of the <polyepoxy compound (B)> described in the first aspect, the description thereof is omitted here.

<Adhesive composition>
The adhesive composition of the present invention contains at least a polyester resin (A2), preferably a polyepoxy compound (B), and has low hygroscopicity, high adhesiveness, and long-term durability in a moist heat environment. It has the effect of being excellent in sex.

In the adhesive composition of the present invention, the contents of the filler, flame retardant, polyepoxy compound (B), solvent, and other optional components contained therein have been described in the above-mentioned first aspect. Since it is the same as the content of <adhesive composition>, the description is omitted here.

<Adhesive>
The adhesive of the present invention is obtained by curing the above-mentioned adhesive composition, and has the effects of excellent initial adhesiveness, low hygroscopicity, and long-term durability in a moist heat environment.
Since the adhesive of the present invention has the same contents as the <adhesive> described in the first aspect described above, the description thereof is omitted here.

<< Third aspect >>
The adhesive composition of the present invention contains at least a polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin will be described.

<Polyester resin>
The polyester resin contains a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and is preferably obtained by ester-bonding the polyvalent carboxylic acid and the polyhydric alcohol. Is something that can be done.

[Multivalent carboxylic acids]
Examples of the polyvalent carboxylic acid in the polyvalent carboxylic acid include an aromatic polyvalent carboxylic acid described later; a trivalent or higher polyvalent carboxylic acid having an acid anhydride group number of 0 or 1 described later; 1,4-cyclohexanedicarboxylic acid. Alicyclic polyvalent carboxylic acids such as acids, 1,3-cyclohexanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids and their acid anhydrides; fats such as succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid. Group polyvalent carboxylic acids can be mentioned. One or more polyvalent carboxylic acids can be used.

The multivalent carboxylic acids include aromatic polyvalent carboxylic acids. Examples of aromatic polyvalent carboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl isophthalate, orthophthalic acid, naphthalenedicarboxylic acid, dimethyl naphthalenedicarboxylic acid, and biphenyldicarboxylic acid, and derivatives thereof (aromatic dicarboxylic acids). ). In addition, aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid can be mentioned. Further, the above-mentioned aromatic polyvalent carboxylic acids also include trifunctional or higher functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and acid value to the polyester resin. Examples of the aromatic carboxylic acid in trifunctional or higher functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethyleneglucolbis (anhydrotrimeritate), glycerol tris (anhydrotrimeritate), and trimellitic acid anhydride. Trimellitic acid dianhydride, oxydiphthalic acid dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 3,3', 4,4'-diphenyltetracarboxylic acid dianhydride , 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride, 2,2'-bis [(dicarboxyphenoxy) phenyl ] Propane dianhydride and the like can be mentioned.
Among these, aromatic dicarboxylic acids are preferable, isophthalic acid, dimethyl isophthalate, and dimethyl naphthalenedicarboxylic acid are particularly preferable, and dimethyl naphthalenedicarboxylic acid is more preferable from the viewpoint of low dielectric properties.

The content of the aromatic polyvalent carboxylic acids with respect to the total polyvalent carboxylic acids is preferably 25 mol% or more, more preferably 40 mol% or more, further preferably 70 mol% or more, and particularly preferably 90 mol% or more. , Most preferably 100 mol%. If the content of the aromatic multivalent carboxylic acid is too small, the long-term durability in a moist heat environment tends to be insufficient, or the low dielectric loss tangent tends to be inferior.

The content of the aromatic polyvalent carboxylic acid with respect to the entire polyester resin is preferably 15 to 70% by weight, more preferably 20 to 65% by weight, still more preferably 25 to 60% by weight, and particularly preferably 30. It is ~ 55% by weight. If the content of the aromatic multivalent carboxylic acid is too small, the initial adhesiveness tends to be insufficient or the initial adhesiveness tends to be inferior, and if it is too large, the initial adhesiveness tends to be insufficient.

The polyvalent carboxylic acids preferably also contain trivalent or higher valent carboxylic acids having an acid anhydride radix of 0 or 1. The valence of the carboxy group in such polyvalent carboxylic acids is preferably 3 to 6 valences, and more preferably 3 to 4 valences. Examples of such polyvalent carboxylic acids include those having an acid anhydride group number of 0 or 1 among the above-mentioned trifunctional or higher functional aromatic polyvalent carboxylic acids. For example, trimellitic acid anhydride, trimellitic acid, trimesic acid and the like can be mentioned. Among these, those having an acid anhydride group number of 1 are preferable, and trimellitic acid anhydride is particularly preferable.
Further, among the trivalent or higher valent carboxylic acids having 0 or 1 acid anhydride groups, those other than the aromatic polyvalent carboxylic acids include, for example, hydrogenated trimellitic acid anhydride and the like.

Aromatic dicarboxylic acids having sulfonic acid groups such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5 (4-sulfophenoxy) isophthalic acid. , And the aromatic dicarboxylic acid salt having a sulfonic acid base such as a metal salt or an ammonium salt thereof has a content of 10 mol% or less with respect to the total polyvalent carboxylic acid from the viewpoint of hygroscopicity of the polyester resin. It is preferably 5 mol% or less, particularly preferably 3 mol% or less, still more preferably 1 mol% or less, and most preferably 0 mol% or less.

[Multivalent alcohols]
Examples of polyhydric alcohols include dimerdiols, bisphenol skeleton-containing monomers, aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, and aromatic polyhydric alcohols. One type or two or more types of polyhydric alcohols can be used.

In the present invention, the compound constituting the polyester resin preferably contains dimerdiols as polyhydric alcohols.
Examples of the dimer diols include dimer diols which are reduced compounds of dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like, and those. Examples of hydrogenated substances. Of these, hydrogenated additives are preferable from the viewpoint of suppressing gelation during the production of the polyester resin.

The content of the dimerdiol in the whole polyhydric alcohols is preferably 5 to 80 mol%, more preferably 10 to 60 mol%, particularly preferably 15 to 55 mol%, still more preferably 20 to 50 mol%. Is. If the content of dimerdiols is too small, the low hygroscopicity and dielectric properties tend to be inferior, and if the content is too large, the initial adhesiveness tends to be insufficient.

The content of the dimerdiols in the entire polyester resin is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, still more preferably 15 to 55% by weight, and particularly preferably 20 to 50% by weight. %. If the content of the dimerdiols is too small, the low hygroscopicity and dielectric properties tend to be inferior, and if the content is too large, the initial adhesiveness tends to be insufficient.

Examples of the bisphenol skeleton-containing monomer include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4'-dihydroxybenzophenone, and bisphenol fluorene. Examples thereof include hydrogenated products thereof, ethylene oxide adducts obtained by adding 1 to several mols of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols, glycols such as propylene oxide adducts, and the like. Among them, bisphenol fluorene having a condensed polycyclic aromatic skeleton is preferable from the viewpoint of low dielectric property, and ethylene oxide adduct is preferable from the viewpoint of reactivity, and particularly heat resistance, low hygroscopicity, and long-term under a moist heat environment. From the viewpoint of durability, an adduct of 2 to 3 mol of ethylene oxide is preferable, and bisphenoloxyethanol fluorene is most preferable.

From the viewpoint of low dielectric properties, it is preferable that the amount of bisphenol skeleton-containing monomer other than bisphenol fluorene and its derivatives is small, but from the viewpoint of solvent solubility of polyester resin, storage stability of the solution, and low hygroscopicity, it is large. It is preferable, and it is preferable to adjust the introduction amount according to the desired physical properties. On the other hand, bisphenol fluorene and its derivatives are preferably introduced into polyester-based resins in all of the above-mentioned solvent solubility, storage stability of the solution, low moisture absorption, and low dielectric properties, and all polyhydric alcohols. The content of bisphenol fluorene and its derivative is preferably 5 to 50 mol%, more preferably 10 to 45 mol%, particularly preferably 15 to 40 mol%, still more preferably 20 to 35 mol%. .. If the content of bisphenol fluorene and its derivatives is too high, the initial adhesiveness tends to be insufficient, and if it is too low, the solvent solubility, storage stability, low hygroscopicity, and dielectric properties tend to be insufficient. is there.

Examples of the aliphatic polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and 1,5-pentane. Diol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, 2-ethyl-2-butylpropanediol, dimethylol Heptane, 2,2,4-trimethyl-1,3-pentanediol and the like can be mentioned. Among them, those having 5 or less carbon atoms are preferably used because the aromatic ring content described later can be increased.

Among the above polyhydric alcohols, it is preferable to use a polyhydric alcohol having a side chain from the viewpoint of solvent solubility and solution stability. Examples of the polyhydric alcohol having a side chain include bisphenol A, bisphenol B, bisphenol E, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, bisphenol fluorene and their hydrogenated products, and bisphenol. A bisphenol skeleton-containing monomer having a side chain such as an ethylene oxide adduct obtained by adding 1 to several mols of ethylene oxide or propylene oxide to a hydroxyl group of the same kind, a propylene oxide adduct, etc., 1,2-propylene glycol, 2-methyl -1,3-Propanediol, neopentylglycol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, dimethylolheptan, 2,2,4-trimethyl-1,3-pentane Examples thereof include aliphatic polyhydric alcohols having side chains such as diols, and alicyclic polyhydric alcohols having side chains such as tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.
The content of the polyhydric alcohol having a side chain is preferably 10 mol% or more, more preferably 20 mol% or more, still more preferably 30 mol% or more, based on the total polyhydric alcohols. The upper limit is 95 mol%. Further, it is 5% by weight or more, more preferably 10% by weight or more, still more preferably 15% by weight or more, based on the entire polyester resin. The upper limit is 50% by weight.
If the content of the polyhydric alcohol having a side chain is too small, the solvent solubility and the solution stability of the obtained polyester resin solution tend to decrease.

[General raw material compounds that make up polyester resins]
As for the compound constituting the polyester resin, it is preferable that at least one of the above polyvalent carboxylic acids and polyhydric alcohols contains a condensed polycyclic aromatic compound from the viewpoint of low dielectric loss tangent. Examples of the condensed polycyclic aromatic compound include naphthalenedicarboxylic acid, dimethyl naphthalenedicarboxylic acid, anthracenedicarboxylic acid and the like as condensed polycyclic aromatic compounds of polyvalent carboxylic acids, among which price and availability are available. Naphthalene dicarboxylic acids are preferable from the viewpoint of the above, and dimethyl naphthalene dicarboxylic acid is more preferable from the viewpoint of reactivity. These can be used alone or in combination of two or more. Examples of the condensed polycyclic aromatic compound of polyhydric alcohols include bisphenol fluorene and derivatives thereof such as ethylene oxide and propyrone oxide adducts. Among them, ethylene oxide adducts are preferable, and bisphenoxyethanol is preferable. Fluorene is particularly preferred. These can be used alone or in combination of two or more.

In the present invention, it is preferable to increase the aromatic ring content from the viewpoint of low dielectric loss tangent.
The aromatic ring content with respect to the entire polyester resin is preferably 10% by weight or more, more preferably 15% by weight or more, particularly preferably 20% by weight or more, still more preferably 25% by weight, from the viewpoint of low dielectric loss tangent. That is all. The upper limit is usually 50% by weight.

Here, the definition and calculation method of the aromatic ring content in the present invention are as follows.
The aromatic ring content is the weight ratio of the atoms constituting the aromatic ring in the polyester resin. The two aromatic ring portions derived from the bisphenol skeleton are not included in the aromatic ring content in the present invention because they do not contribute to the low dielectric property. The reason why the two aromatic ring portions derived from the bisphenol skeleton do not contribute to the low dielectric loss tangent is not clear, but it is presumed that the two aromatic rings derived from the bisphenol skeleton cannot participate in stacking between aromatic rings, for example, due to steric factors. ..

The aromatic ring content is calculated from the composition of the polyester resin. The calculation method is as follows.
Aromatic ring content = A1 x (a11 x m11 + a12 x m12 + a13 x m13 ...) / (x1-y1) + A2 x (a21 x m21 + a22 x m22 + a23 x m23 ...) / (x2-y2) + A3 x (a31 x) m31 + a32 x m32 + a33 x m33 ...) / (x3-y3) ...
A: Content of structural units derived from each monomer in polyester resin (% by weight)
a: Atomic weight of atoms constituting the aromatic ring in each monomer (for example, 12 for carbon, 14, 14 for nitrogen, etc. When two or more kinds of atoms are present, a11 in the above formula, a. Corresponds to a12, a13, ..., For example, a11: carbon, a12: nitrogen, a13: oxygen.)
m: Number of atoms constituting the aromatic ring in each monomer x: Molecular weight of each monomer y: Sum of the formula amounts of leaving groups in each monomer The two aromatic ring sites derived from the bisphenol skeleton are for the above reasons. As shown above, it is not included as an atom constituting the aromatic ring (treated as m = 0).

Further, an oxycarboxylic acid compound having a hydroxyl group and a carboxy group in its molecular structure can also be used as a raw material compound for a polyester resin. Examples of such oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis ( p-Hydroxyphenyl) Valeric acid and the like can be mentioned.

The polyester resin used in the present invention has a trifunctional or higher functional polyvalent carboxylic acid and a trifunctional or higher functional polyvalent resin for the purpose of introducing a branched skeleton, in addition to the polyvalent carboxylic acids used in the depolymerization reaction described later. It is preferable that at least one selected from the group consisting of valent alcohols is copolymerized. In particular, when a cured coating film is obtained by reacting with a curing agent, the introduction of a branched skeleton increases the terminal group concentration (reaction point) of the resin, and a strong coating film having a high crosslink density can be obtained.

At least one selected from the group consisting of trifunctional or higher functional polyvalent carboxylic acids and trifunctional or higher functional alcohols for the purpose of introducing a branched skeleton, in addition to the polyvalent carboxylic acids used in the depolymerization reaction described later. When using, the content of the trifunctional or higher polyvalent carboxylic acid with respect to the entire polyhydric carboxylic acid, or the content of the trifunctional or higher polyhydric alcohol with respect to the entire polyhydric alcohol is preferably 0.1. It is in the range of ~ 5 mol%, more preferably 0.3 to 3 mol%, still more preferably 0.5 to 2 mol%. If the content of both or one of them is too large, the mechanical properties such as the elongation at the breaking point of the coating film formed by the application of the adhesive are lowered, and the adhesive strength tends to be lowered, and during the polymerization. It also tends to gel.

[Manufacturing of polyester resin]
The polyester resin used in the present invention can be produced by a well-known method. For example, polyhydric carboxylic acids and polyhydric alcohols can be produced by subjecting them to an esterification reaction in the presence of a catalyst, if necessary, to obtain a polyester resin, and further introducing an acid value. it can.

When the total polyvalent carboxylic acids constituting the polyester resin are 100 mol%, gelation may occur if an acid addition of 15 mol% or more is performed. Examples of the acid addition method include a method of directly adding in a bulk state and a method of adding polyester as a solution. The reaction in the bulk state is fast, but if a large amount is added, gelation may occur and the reaction is carried out at a high temperature. Therefore, care must be taken such as blocking oxygen gas to prevent oxidation. On the other hand, the addition in the solution state has a slow reaction, but a large amount of carboxy groups can be stably introduced.

In the present invention, another well-known method, for example, polyhydric carboxylic acids and polyhydric alcohols are subjected to an esterification reaction in the presence of a catalyst, if necessary, to obtain a prepolymer. , It can be produced by performing polycondensation and further depolymerizing.

For depolymerization, it is preferable to use trivalent or higher valent carboxylic acids having an acid anhydride radix of 0 or 1, from the viewpoint of initial adhesiveness. Examples of trivalent or higher valent carboxylic acids having 0 or 1 acid anhydride groups include compounds such as trimellitic acid, trimellitic acid anhydride, hydrogenated trimellitic acid anhydride, and trimesic acid. Preferably, it is a trivalent or higher valent carboxylic acid having 1 acid anhydride group from the viewpoint of suppressing a decrease in molecular weight, and examples thereof include trimellitic acid anhydride and hydrogenated trimellitic acid anhydride. Trimellitic anhydride is preferable from the viewpoint of low dielectric rectification.
The temperature in the depolymerization is usually 200 to 260 ° C., and the reaction time is usually 10 minutes to 3 hours.

When the total polyvalent carboxylic acids constituting the polyester resin are 100 mol%, depolymerization is performed using more than 20 mol% of trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups. In some cases, the molecular weight of the resin may be significantly reduced. Therefore, when the total polyvalent carboxylic acids constituting the polyester resin are 100 mol%, depolymerization is performed using 20 mol% or less of trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups. Depolymerization is preferably carried out using 1 to 15 mol%, particularly preferably 2 to 10 mol%, still more preferably 3 to 8 mol%.

[Glass transition temperature (Tg) of polyester resin]
The glass transition temperature (Tg) of the polyester resin used in the present invention is the same as the content of the glass transition temperature described in the first aspect. That is, it is −5 ° C. or higher, preferably 0 to 100 ° C., more preferably 3 to 80 ° C., particularly preferably 5 to 60 ° C., still more preferably 7 to 40 ° C., and most preferably 10 to 30 ° C.
If the glass transition temperature (Tg) is too low, the initial adhesiveness and tack-free property become insufficient. If the glass transition temperature (Tg) is too high, the initial adhesiveness and flexibility tend to be insufficient.

[Acid value of polyester resin]
The acid value of the polyester resin used in the present invention is 3 mgKOH / g or more, preferably 4 to 60 mgKOH / g, more preferably 5 to 40 mgKOH / g, particularly preferably 6 to 30 mgKOH / g, still more preferably 7 to 20 mgKOH. / G.
If the acid value is too low, when the adhesive composition contains a curing agent such as a polyepoxy compound, the cross-linking point with the curing agent is insufficient and the degree of cross-linking is lowered, so that the heat resistance becomes insufficient. In addition, if the acid value is too high, the hygroscopicity and long-term durability in a moist heat environment will decrease, and a large amount of curing agent will be required at the time of curing. Tends to be difficult to obtain.

The definition and measurement method of acid value are as follows.
The acid value (mgKOH / g) can be determined by dissolving 1 g of a polyester resin in 30 g of a mixed solvent of toluene / methanol (for example, toluene / methanol = 7/3 by volume) and neutralizing titration based on JIS K0070. it can.
In the present invention, the acid value of the polyester resin is due to the content of the carboxy group in the resin.

[Ester bond concentration of polyester resin]
The ester bond concentration of the polyester resin used in the present invention is preferably 7.5 mmol / g or less, more preferably 2 to 7 mmol / g, still more preferably 2.5 to 6.5 mmol / g. It is particularly preferably 3 to 6 mmol / g, and particularly preferably 3.1 to 5.5 mmol / g.
If the ester bond concentration is too high, the low hygroscopicity tends to be insufficient, and if the ester bond concentration is too low, the initial adhesiveness tends to be insufficient.

The definition and measurement method of the ester bond concentration are the same as the contents of the ester bond concentration described in the first aspect. That is, it is as follows.
The ester bond concentration (mmol / g) is the number of moles of ester bonds in 1 g of the polyester resin, and is obtained by, for example, a calculated value from the charged amount. Such a calculation method is a value obtained by dividing the number of moles of the smaller amount of each of the charged amounts of the polyvalent carboxylic acids and the polyhydric alcohols by the total weight of the resin, and an example of the calculation formula is shown below.
When the amounts of the polyvalent carboxylic acids and the polyhydric alcohols charged are the same molar amount, either of the following calculation formulas may be used.
Further, when a monomer having both a carboxy group and a hydroxyl group is used as a monomer, or when polyester is produced from caprolactone or the like, the calculation method is appropriately changed.

The concentration of other polar groups other than the ester bond and the reactive functional group is the same as that described in the first aspect. That is, it is preferably low from the viewpoint of low hygroscopicity and long-term durability in a moist heat environment.
Examples of other polar groups include an amide group, an imide group, a urethane group, a urea group, an ether group, a carbonate group and the like.

[Peak top molecular weight (Mp) and weight average molecular weight (Mw) of polyester resin]
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) of the polyester resin used in the present invention are the same as the contents of the peak top molecular weight (Mp) and the weight average molecular weight (Mw) described in the first aspect. is there. That is, the peak top molecular weight (Mp) of the polyester resin is preferably 5000 to 150,000, more preferably 10000 to 100,000, particularly preferably 15,000 to 70,000, and further preferably 25,000 to 40,000.
If the peak top molecular weight (Mp) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the peak top molecular weight (Mp) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

The weight average molecular weight (Mw) of the polyester resin used in the present invention is preferably 5000 to 300,000, more preferably 10,000 to 200,000, particularly preferably 20,000 to 150,000, and even more preferably 30,000 to 100,000.
If the weight average molecular weight (Mw) is too low, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, or flexible laminated boards such as flexible copper-clad laminates and flexible printed circuit boards will be manufactured. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and seep out during press working. Further, if the weight average molecular weight (Mw) is too high, the initial adhesiveness tends to be insufficient, or the solution viscosity at the time of coating is too high, and it tends to be difficult to obtain a uniform coating film.

[Water absorption rate of polyester resin (% by weight)]
The water absorption rate of the polyester resin used in the present invention is the same as the content of the water absorption rate described in the first aspect. That is, it is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, still more preferably 0.6% by weight or less.
If the water absorption rate is too high, the moist heat durability and insulation reliability tend to decrease, and the dielectric properties tend to be inferior.

The method for measuring the water absorption rate is as follows.
A polyester resin solution (before compounding the curing agent) was applied on a release film with an applicator and dried at 120 ° C. for 10 minutes to prepare a sheet having a dry film thickness of 65 μm. This sheet was cut into a size of 7.5 cm × 11 cm, the polyester resin layer surface of the sheet was laminated on a glass plate, and then the release film was peeled off. By repeating this operation 6 times, a test plate having a polyester resin layer having a thickness of 390 μm on the glass plate is obtained.
The test plate thus obtained was immersed in purified water at 23 ° C. for 24 hours, then taken out, the surface of the test plate was wiped off, and dried at 70 ° C. for 2 hours. The weight required in each of these steps is measured, and the water absorption rate (% by weight) is calculated from the weight change according to the following formula.
(Cd) × 100 / (ba)
a: Weight of the glass plate alone b: Weight of the initial test plate c: Weight of the test plate immediately after being taken out from purified water and wiped off d: Weight of the test plate after drying at 70 ° C. for 2 hours

[Dielectric properties of polyester resin]
(Relative permittivity (Dk))
The relative permittivity of the polyester resin used in the present invention at a temperature of 23 ° C. and a relative humidity of 50% RH at a frequency of 10 GHz is preferably 2.8 or less, more preferably 2.7 or less, and particularly preferably 2.6. Below, it is more preferably 2.5 or less. If the relative permittivity is too high, the transmission speed when used as a substrate tends to be inferior or the transmission loss tends to increase.

(Dissipation factor (Df))
The dielectric loss tangent of the polyester resin used in the present invention at a temperature of 23 ° C. and a relative humidity of 50% RH at a frequency of 10 GHz is 0.005 or less, preferably 0.0045 or less, more preferably 0.004 or less. It is particularly preferably 0.0035 or less, further preferably 0.003 or less, particularly preferably 0.0025 or less, and most preferably 0.002 or less. If the dielectric loss tangent is too high, the transmission loss when the substrate is used becomes large.

The relative permittivity and dielectric loss tangent can be measured by the cavity resonator perturbation method using a network analyzer. If the adhesiveness of the polyester resin is so strong that it is difficult to prepare a measurement sample by itself, the dielectric property of the polyester resin alone can be calculated by measuring in a sanded state on the film and subtracting the film content. it can.

Thus, in the present invention, a polyester resin having a very small dielectric loss tangent can be obtained as compared with the conventional one.
A polyester resin having a very small dielectric loss tangent is very useful as a raw material for an adhesive used for bonding electronic material members or the like because it can suppress transmission loss in a high frequency region.

Further, in the present invention, a non-crystalline polyester resin is preferable in terms of solvent solubility and solution stability thereof. If it is crystalline, the solvent solubility and its solution stability tend to be insufficient.
Non-crystallinity can be confirmed by a differential scanning calorimeter. For example, when measured at a measurement temperature range of −70 to 400 ° C. and a temperature rise rate of 10 ° C./min, no endothermic peak due to crystal melting is observed. .. The measurement temperature range and the rate of temperature rise can be appropriately changed according to the sample.

Further, in the present invention, it is preferable that the polyester-based resin is soluble in a non-halogen-based organic solvent from the viewpoint of forming an adhesive composition described later. If the solubility in such an organic solvent is insufficient, it tends to be difficult to prepare an adhesive composition.

The non-halogen organic solvent is, for example, an aromatic solvent such as toluene, xylene, solvent naphtha, or sorbasso, a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone, methyl alcohol, ethyl alcohol, isopropyl alcohol, or isobutyl. It is an alcohol solvent such as alcohol, an ester solvent such as ethyl acetate or normal butyl acetate, an acetate solvent such as cellosolve acetate or methoxyacetate, or a mixture of two or more of these solvents.

<Hardener>
The adhesive composition of the present invention preferably further contains a curing agent. By containing a curing agent, the functional group in the polyester resin reacts with the curing agent having a functional group that reacts with the functional group and is cured, so that the adhesive has excellent adhesive strength, heat resistance, and durability. Can be obtained.
Examples of such a curing agent include compounds having a functional group that reacts with at least one of a hydroxyl group and a carboxy group contained in a polyester resin, such as a polyisocyanate compound and a polyepoxy compound, and among them, solder heat resistant. In terms of points, it is preferably a polyepoxy compound.

Examples of the polyisocyanate compound include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydride diphenylmethane diisocyanate, xylylene diisocyanate, and hydride xylylene diisocyanate. Examples thereof include a tolylene diisocyanate adduct of trimethylolpropane, an isocyanate adduct such as a hexamethylene diisocyanate adduct and an isophorone diisocyanate adduct. The polyisocyanate compound may be used even if the isocyanate portion is blocked with phenol, lactam or the like. One of these isocyanate compounds may be used alone, or two or more thereof may be mixed and used.

Examples of the polyepoxide-based compound include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; and polyfunctional such as phenol novolac glycidyl ether and cresol novolac glycidyl ether. Glycidyl ether type; Glycidyl ester type such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; alicyclic group such as triglycidyl isocyanurate, 3,4-epoxide cyclohexylmethylcarboxylate, epoxidized polybutadiene, epoxidized soybean oil or Examples include aliphatic epoxides. As these polyepoxy compounds, one kind or two or more kinds can be used. Among them, the glycidyl ether type and the glycidyl ester type are preferable from the viewpoint of reactivity, the glycidyl ether type is preferable from the viewpoint of wet heat durability, and the polyfunctional type is preferable from the viewpoint of solder heat resistance.

Further, the epoxy equivalent of the polyepoxy compound is preferably 500 g / eq or less, more preferably 350 g / eq or less, particularly preferably 250 g / eq or less, still more preferably 200 g / eq or less. If the epoxy equivalent of the polyepoxy compound is too large, the crosslink density after curing will be low, resulting in inferior solder heat resistance, or inferior dielectric properties due to the need to add a large amount of polyepoxy compound to increase the crosslink density. Tend.

Further, when a polyester-containing polyepoxy compound (nitrogen atom-containing polyepoxy compound) is contained as the polyepoxy compound, the coating film of the adhesive composition is B-staged (semi-) by heating at a relatively low temperature. It tends to be able to be in a cured state), and the fluidity of the B stage film can be suppressed to improve workability in the bonding operation. Further, the effect of suppressing the foaming of the B stage film can be expected, which is preferable.

When the adhesive composition of the present invention contains a polyepoxy compound, and the polyepoxy compound further contains these nitrogen atom-containing polyepoxy compounds, the content of the nitrogen atom-containing polyepoxy compound is poly. It is preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less based on the total epoxy compound.
The content of the nitrogen atom-containing polyepoxy compound is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight or less, based on 100 parts by weight of the polyester resin. Is.
If the content of the nitrogen atom-containing polyepoxy compound is too large, the rigidity tends to be excessively high and the adhesiveness tends to decrease, and the cross-linking reaction tends to proceed during the storage of the adhesive sheet, resulting in a decrease in sheet life. Tend to do.

The equivalent of the epoxy group to the carboxy group (COOH) is calculated by the following formula from the acid value of the polyester resin and the epoxy equivalent (g / eq) of the blended polyepoxy compound.
Epoxy equivalent to COOH = (a ÷ WPE) / (AV ÷ 56.1 ÷ 1000 × b)
a: Weight (g) of the polyepoxy compound used in the formulation
WPE: Epoxy equivalent of polyepoxy compound (g / eq)
AV: Acid value of polyester resin (mgKOH / g)
b: Weight (g) of polyester resin used for compounding

<Adhesive composition>
The adhesive composition of the present invention contains at least the polyester resin of the present invention, preferably further contains a curing agent, has excellent low dielectric properties, has low hygroscopicity, high adhesiveness, and is long-term in a moist heat environment. It has the effect of being excellent in durability.

In the adhesive composition of the present invention, a filler, a flame retardant, etc. may be blended. In that case, the content of the polyester resin of the present invention in the adhesive composition shall be a filler, a flame retardant, or the like. In consideration of the above, it is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, still more preferably 60 to 85% by weight, based on the total solid content.

When the adhesive composition of the present invention contains a curing agent, the content of the curing agent is preferably 1 to 30 parts by weight, more preferably 2 to 3 parts by weight, based on 100 parts by weight of the polyester resin of the present invention. It is 20 parts by weight, particularly preferably 3 to 15 parts by weight, and even more preferably 4 to 10 parts by weight. If the content of the curing agent is too small, the heat resistance and long-term durability in a moist heat environment tend to be insufficient, and if it is too large, the initial adhesiveness and low hygroscopicity are insufficient, and the dielectric properties are inferior. Tend to do.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the example, "part" and "%" mean the weight standard.

<< First aspect >>
Ratio of aromatic polyvalent carboxylic acids to the total polyvalent carboxylic acids (mol%) (denoted as "aromatic acid content" in Table 1-1), ester bond concentration (mmol / g), water absorption rate, glass transition The temperature (° C.), acid value (mgKOH / g), peak top molecular weight (Mp), weight average molecular weight (Mw), and equivalent of the epoxy group to COOH were measured according to the description herein.

<Manufacturing of polyester resin>
The composition (molar ratio) shown in Table 1-1 below is the composition ratio (resin composition ratio) of the finished product, and is the relative ratio (molar ratio) of the amounts of each constituent monomer of the obtained polyester resin.

[Manufacturing Example 1-1: Production of polyester resin (A1-1)]
In a reaction can equipped with a thermometer, agitator, a rectification tower, and a nitrogen introduction tube, 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as polyhydric carboxylic acids and ethylene oxide of bisphenol A as polyhydric alcohols. Approximately 2 mol of oxide Additive "New Pole BPE-20" (BPE-20) (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 223.9 parts (0.6868 mol), neopentyl glycol (NPG) 28.6 parts (0.2746) Mol), dimerdiol "Pripole 2033" (P2033) (manufactured by Claude) 254.4 parts (0.4801 mol), and 0.1 part of tetrabutyl titanate as a catalyst, 120 minutes until the internal temperature reaches 270 ° C. The temperature was raised over 3 hours, and the esterification reaction was carried out at 270 ° C. for 3 hours.
Next, the internal temperature was lowered to 200 ° C., 15.0 parts (0.0688 mol) of pyromellitic dianhydride (PMAn) was added, and an addition reaction was carried out at 200 ° C. for 2 hours. The resins shown in Table 1-1 were added. A polyester resin (A1-1) having a composition and various physical properties was obtained.

[Production Examples 1-2, Comparative Production Examples 1-1 to 1-3: Production of Polyester Resins (A1-2, A1'-1, A1'-2, A1'-3)]
Polyester resins (A1-2, A1'-1, A1'-2, A1'-3) were obtained in the same manner as A1-1 except that the resin composition was changed as shown in Table 1-1. It was.

Table 1-1 shows the resin composition (structural unit derived from the components) and various physical properties of the obtained polyester resin. In Table 1-1, each abbreviation is as follows.
"TPA": terephthalic acid "IPA": isophthalic acid "AdA": adipic acid "P1010": dimer acid "Pripol 1010" (manufactured by Croda)
"PMAn": pyromellitic dianhydride "BPDA": 3,3', 4,4', -diphenyltetracarboxylic dianhydride "EG": ethylene glycol "NPG": neopentyl glycol "BPE-20" : Approximately 2 mol of ethylene oxide adduct of bisphenol A "Nieuport BPE-20" (manufactured by Sanyo Kasei Kogyo Co., Ltd.)
"P2033": Dimerdiol "Pripole 2033" (manufactured by Croda)

<Polyepoxy compound (B)>
The following were prepared as the polyepoxy compound (B).
(B1-1): Phenolic novolac type epoxy resin "YDPN-638" (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) (WPE = 177 (g / eq))

<Manufacturing of adhesive composition>
Using the polyester resin and polyepoxy compound obtained above, an adhesive composition was produced as follows.

(Example 1-1)
The polyester resin (A1-1) obtained above is diluted with methyl ethyl ketone to a solid content concentration of 60%, and a polyepoxy compound (100 parts as a solid content) is added to the polyester resin (A1-1) solution (solid content). An adhesive composition was obtained by blending 10 parts of B1-1) (solid content), further diluting with methyl ethyl ketone so as to have a solid content of 50%, stirring, and mixing.

(Examples 1-2 to 1-3, Comparative examples 1-1 to 1-5)
In Example 1-1, an adhesive composition was obtained in the same manner except that the resin composition was as shown in Table 1-2.
The obtained adhesive composition was used for evaluation as follows. The results are shown in Table 1-2.

<Manufacturing of laminated body>
The adhesive composition prepared above was applied to a polyimide film "Kapton 200H" (manufactured by Toray DuPont) having a thickness of 50 μm with an applicator, and then dried at 120 ° C. for 5 minutes to form an adhesive layer having a dry thickness of 25 μm. .. Next, (1) a rolled copper foil having a thickness of 30 μm or (2) a polyimide film “Kapton 200H” having a thickness of 50 μm is laminated with the adhesive layer surface of the polyimide film with an adhesive layer (lamination conditions: 170 ° C., 0.2 MPa, respectively). The feed rate was 1.5 m / min), and then heat treatment and curing were performed in an oven at 160 ° C. for 4 hours to obtain each laminate.
For convenience, the laminate (polyimide film / adhesive layer / rolled copper foil) laminated with the rolled copper foil is referred to as PI / Cu, and the laminate (polyimide film / adhesive layer / polyimide film) laminated with the polyimide film is described as PI / PI. Notated as.

<Evaluation>
[Initial adhesive strength]
The laminate obtained above was cut out to a width of 1 cm and used as a test piece. The test piece was fixed to a glass plate having a thickness of 2 mm using double-sided tape, and the tensile peel strength of the test piece was measured using a peeling tester in an environment of 23 ° C. and 50% RH (peeling speed: 50 mm / min). , Peeling angle: 180 °). The evaluation criteria are as follows.
⊚: 8 N / cm or more ○: 6 N / cm or more, less than 8 N / cm Δ: 4 N / cm or more, less than 6 N / cm ×: less than 4 N / cm

[Moist heat durability]
The PI / Cu test piece was placed in a constant temperature and humidity chamber at 85 ° C. and 85% RH, taken out after a predetermined time, allowed to stand overnight in an environment of 23 ° C. and 50% RH, and then subjected to the same initial adhesive strength as described above. The tensile peel strength was measured. The percentage of the adhesive force after the wet heat treatment with respect to the initial adhesive force was defined as the "maintenance rate".
The absolute value of the adhesive strength was evaluated using the same evaluation criteria as the initial adhesive strength.
The maintenance rate of adhesive strength was evaluated based on the following evaluation criteria.
⊚: Maintenance rate is 80% or more ○: Maintenance rate is 60% or more and less than 80% Δ: Maintenance rate is 40% or more and less than 60% ×: Maintenance rate is less than 40%

[Tack-free]
The adhesive layer surface of the polyimide film with the adhesive layer before curing obtained above was lightly touched with a finger and evaluated based on the following evaluation criteria.
◎: Almost no stickiness is felt.
〇: I don't feel much stickiness.
Δ: Somewhat sticky.
×: Sticks to the finger.

[Gel fraction]
The polyimide film with an adhesive layer obtained above was heat-treated at 160 ° C. for 4 hours to be cured, and then cut into a size of 4 cm × 4 cm. This was wrapped in a 200 mesh SUS wire mesh and immersed in methyl ethyl ketone at 23 ° C. for 24 hours, and the weight percentage of the insoluble adhesive component remaining in the wire mesh with respect to the adhesive weight before immersion was defined as the gel fraction.

From the results of Tables 1-1 and 1-2 above, the polyester resins (A1-1) and (A1-2) of Production Examples 1-1 and 1-2 satisfying the requirements of the present invention are excellent in low hygroscopicity. The adhesive compositions of Examples 1-1 to 1-3 obtained using them are excellent in tack-free property before curing, initial adhesive property after curing, and long-term durability in a moist heat environment. Is.
On the other hand, the polyester resin (A1'-1) of Comparative Production Example 1-1 having a high ester bond concentration has high hygroscopicity, and Comparative Examples 1-1 and 1-2 obtained by using the polyester resin have high hygroscopicity in a moist heat environment. It was inferior in long-term durability. Similarly, the adhesive compositions of Comparative Examples 1-3 and 1-4 obtained by using the polyester resin (A1'-2) of Comparative Production Example 1-2 having a high ester bond concentration also under a moist heat environment. It was inferior in long-term durability.
Further, the adhesive composition of Comparative Example 1-5 obtained by using the polyester resin (A1'-3) of Comparative Production Example 1-3 having a low glass transition temperature has a tack-free property before curing and a tack-free property after curing. It was inferior in the initial adhesiveness of.

<< Second aspect >>
Ratio of aromatic polyvalent carboxylic acids to the total polyvalent carboxylic acids (mol%) (denoted as "aromatic acid content" in Table 2-1), ester bond concentration (mmol / g), water absorption rate, glass transition The temperature (° C.), acid value (mgKOH / g), peak top molecular weight (Mp), weight average molecular weight (Mw), and equivalent of the epoxy group to COOH were measured according to the description herein.

<Manufacturing of polyester resin>
The composition (molar ratio) shown in Table 2-1 below is the finished composition ratio (resin composition ratio), and is the relative ratio (molar ratio) of the amounts of each constituent monomer of the obtained polyester resin.

[Manufacturing Example 2-1: Production of polyester resin (A2-1)]
231.1 parts (1.3910 mol) of isophthalic acid (IPA) and trimellitic anhydride (TMAn) 2 as polyvalent carboxylic acids in a reaction can equipped with a thermometer, a stirrer, a rectification tower, and a nitrogen introduction tube. .7 parts (0.0141 mol), about 2 mol of ethylene oxide adduct of bisphenol A as polyhydric alcohol "New Pole BPE-20" (BPE-20) (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 230.1 parts (0) .7058 mol), 57.0 parts (0.9183 mol) of ethylene glycol (EG), 261.5 parts (0.4941 mol) of dimerdiol "Pripol 2033" (P2033) (manufactured by Crowder), tetrabutyl as a catalyst 0.1 part of titanate was charged, the temperature was raised over 2.5 hours until the internal temperature reached 270 ° C., and the esterification reaction was carried out at 270 ° C. for 1.5 hours.
Next, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure inside the system was reduced to 2.5 hPa, and the polymerization reaction was carried out over 3 hours.
Then, the internal temperature was lowered to 240 ° C., 17.6 parts (0.0916 mol) of trimellitic anhydride (TMAn) was added, and a depolymerization reaction was carried out at 240 ° C. for 1 hour to carry out a polyester resin (A2-1). Got

[Production Examples 2-2 to 2-4, Comparative Production Example 2-5: Production of Polyester Resins (A2-2) to (A2-4) and (A2'-5)]
Polyester resins (A2-2) to (A2-4) and (A2'-5) were obtained in the same manner as in A2-1 except that the resin composition was changed as shown in Table 2-1.

[Comparative Production Example 2-1: Production of Polyester Resin (A2'-1)]
In a reaction can equipped with a thermometer, agitator, a rectification tower, and a nitrogen introduction tube, 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as polyhydric carboxylic acids and ethylene oxide of bisphenol A as polyhydric alcohols. Approximately 2 mol of oxide Additive "New Pole BPE-20" (BPE-20) (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 223.9 parts (0.6868 mol), neopentyl glycol (NPG) 28.6 parts (0.2746) Mol), dimerdiol "Pripole 2033" (P2033) (manufactured by Claude) 254.4 parts (0.4801 mol), and 0.1 part of tetrabutyl titanate as a catalyst were charged, and it took 2 hours until the internal temperature reached 270 ° C. The temperature was raised over and the esterification reaction was carried out at 270 ° C. for 3 hours.
Next, the internal temperature was lowered to 200 ° C., 15.0 parts (0.0688 mol) of pyromellitic dianhydride (PMAn) was added, and a double addition reaction was carried out at 200 ° C. for 2 hours to carry out a polyester resin (A2'). -1) was obtained.

[Comparative Production Examples 2-2 to 2-4: Production of Polyester Resins (A2'-2) to (A2'-4)]
Polyester resins (A2'-2) to (A2'-4) were obtained in the same manner as A2'-1 except that the resin composition was changed as shown in Table 2-1.

Table 2-1 shows the resin composition (structural unit derived from the components) and various physical properties of the obtained polyester resin. The abbreviations in Table 2-1 are as follows.
"TPA": Terephthalic acid "IPA": Isophthalic acid "TMAn": Trimellitic acid anhydride "AdA": Adipic acid "P1009": Dimeric acid "Pripol 1009" (manufactured by Croda)
"P1010": Dimer acid "Pripole 1010" (manufactured by Croda)
"PMAn": pyromellitic dianhydride "BPDA": 3,3', 4,4', -diphenyltetracarboxylic dianhydride "EG": ethylene glycol "NPG": neopentyl glycol "BPE-20" : Approximately 2 mol of ethylene oxide adduct of bisphenol A "Nieuport BPE-20" (manufactured by Sanyo Kasei Kogyo Co., Ltd.)
"P2033": Dimerdiol "Pripole 2033" (manufactured by Croda)

<Polyepoxy compound (B)>
The following were prepared as the polyepoxy compound (B).
(B2-1): Phenolic novolac type epoxy resin "YDPN-638" (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) (WPE = 177 (g / eq))

<Manufacturing of adhesive composition>
Using the polyester resin and the polyepoxy compound (B) obtained above, an adhesive composition was produced as follows.

(Example 2-1)
The polyester resin (A2-1) obtained above is diluted with a mixed solvent of toluene / methyl ethyl ketone = 5/1 (weight ratio) to a solid content concentration of 55%, and this polyester resin (A2-1) solution (solid content). The adhesive composition is prepared by blending 10 parts of the polyepoxy compound (B2-1) (solid content) with respect to 100 parts), and further diluting, stirring, and mixing with methyl ethyl ketone so that the solid content becomes 50%. Got

(Examples 2-2 to 2-4, Comparative Examples 2-1 to 2-6)
In Example 2-1 an adhesive composition was obtained in the same manner except that the resin compositions shown in Table 2-2 were used.
The obtained adhesive composition was used for evaluation as follows. The results are shown in Table 2-2.

<Manufacturing of laminated body>
The adhesive composition produced above was applied to a polyimide film "Kapton 200H" (manufactured by Toray DuPont) having a thickness of 50 μm with an applicator, and then dried at 120 ° C. for 5 minutes to form an adhesive layer having a dry film thickness of 25 μm. .. Next, a rolled copper foil having a thickness of 30 μm was laminated with the adhesive layer surface of the polyimide film with the adhesive layer (lamination conditions: 170 ° C., 0.2 MPa, feed rate 1.5 m / min), and then in an oven at 160 ° C. for 4 hours. A laminate (PI (base material) / Cu (adhesive)) was obtained by heat treatment and curing.

<Evaluation>
[Initial adhesive strength]
The laminate obtained above was cut out to a width of 1 cm and used as a test piece. The test piece is fixed to a glass plate with a thickness of 2 mm using double-sided tape, and the polyimide film side of the laminate is pulled using a peeling tester in an environment of 23 ° C. and 50% RH, and the tensile peeling strength of the test piece is measured. (Peeling speed: 50 mm / min, peeling angle: 180 °). The evaluation criteria are as follows.
⊚: 12 N / cm or more ○: 9 N / cm or more, less than 12 N / cm Δ: 6 N / cm or more, less than 9 N / cm ×: less than 6 N / cm

[Moist heat durability]
The test piece was placed in a constant temperature and humidity chamber at 85 ° C. and 85% RH, taken out after a predetermined time, allowed to stand overnight in an environment of 23 ° C. and 50% RH, and then subjected to tensile peeling in the same manner as the initial adhesive strength described above. The intensity was measured. The percentage of the adhesive force after the wet heat treatment with respect to the initial adhesive force was defined as the "maintenance rate".
The absolute value of the adhesive strength was evaluated using the same evaluation criteria as the above initial adhesive strength.
The maintenance rate of adhesive strength was evaluated based on the following evaluation criteria.
⊚: Maintenance rate is 80% or more ○: Maintenance rate is 60% or more and less than 80% Δ: Maintenance rate is 40% or more and less than 60% ×: Maintenance rate is less than 40%

From the results in Table 2-1 above, the polyester resins (A2-1) to (A2-4) that satisfy the requirements of the present invention obtained in Production Examples 2-1 to 2-4 are excellent in low hygroscopicity. I understand. Further, from the results in Table 2-2 above, the adhesive compositions of Examples 2-1 to 2-4 obtained by using these polyester resins (A2-1) to (A2-4) are in a moist heat environment. It can be seen that it has excellent long-term durability and also has high adhesiveness.
On the other hand, the polyester-based resins obtained in Comparative Production Examples 2-1 and 2-2 in which acid values were imparted to other than trivalent or higher valent carboxylic acids (x1) having an acid anhydride group number of 0 or 1. The adhesive compositions of Comparative Examples 2-1 and 2-2 obtained using A2'-1) and (A2'-2) are excellent in long-term durability in a moist heat environment, but have excellent adhesiveness. It was lower than that of the examples.
Further, the polyester resins (A2'-3) and (A2'-4) having high ester bond concentrations obtained in Comparative Production Examples 2-3 and 2-4 have high hygroscopicity and were obtained by using them. Some of the adhesive compositions of Comparative Examples 2-3 to 2-5 had good initial adhesiveness, but were inferior in long-term durability in a moist heat environment.
Further, although the polyester resin (A2'-5) having a low aromatic acid content obtained in Comparative Production Example 2-5 has low hygroscopicity, the adhesive of Comparative Example 2-6 obtained by using them. The composition had low initial adhesiveness and was also inferior in long-term durability in a moist heat environment.

<< Third aspect >>
Aromatic ring content, glass transition temperature (° C.), acid value (mgKOH / g), ester bond concentration (mmol / g), peak top molecular weight (Mp), weight average molecular weight (Mw), dielectric properties, epoxy group for COOH Epoxides were measured as described herein. Other methods for measuring physical properties are as follows.

[Dimerdiol content]
The content (% by weight) of dimerdiol with respect to the polyester resin is shown.

<Manufacturing of polyester resin>
The composition described in Table 3-1 below is the composition ratio (resin composition ratio) of the finished product, which is the relative ratio (molar ratio) of the amounts of each constituent monomer of the obtained polyester resin and its weight%.

[Manufacturing of polyester resin (A-1)]
263.7 parts (1.5872 mol) of isophthalic acid (IPA) and trimellitic anhydride (TMAn) 3 as polyvalent carboxylic acids in a reaction can equipped with a thermometer, a stirrer, a rectification tower, and a nitrogen introduction tube. . 1 part (0.0161 mol), about 2 mol of ethylene oxide adduct of bisphenol A as polyhydric alcohol "New Pole BPE-20" (BPE-20) (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 105.0 parts (0) .3221 mol), ethylene glycol (EG) 65.0 parts (1.0472 mol), dimerdiol "Pripol 2033" (P2033) (manufactured by Crowder) 234.5 parts (0.4431 mol), neopentyl glycol (. 62.9 parts (0.6039 mol) of NPG) and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the temperature was raised over 2.5 hours until the internal temperature reached 270 ° C., and the temperature was raised at 270 ° C. for 1.5 hours. , The esterification reaction was carried out.
Next, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure inside the system was reduced to 2.5 hPa, and the polymerization reaction was carried out over 2 hours.
Then, the internal temperature was lowered to 230 ° C., 15.8 parts (0.0822 mol) of trimellitic anhydride (TMAn) was added, and a depolymerization reaction was carried out at 230 ° C. for 1 hour to carry out a polyester resin (A-1). Got

[Manufacturing of polyester resins (A-2 to 8, A'-1 to 2)]
Polyester resins (A-2 to 8, A'-1 to 2) were obtained in the same manner as in A-1, except that the resin composition was changed as shown in Table 3-1.

Table 3-2 shows the resin composition (structural unit derived from the components) and various physical properties of the obtained polyester resin. In Table 3-1 each abbreviation is as follows.
"NDCM": Dimethyl naphthalenedicarboxylic acid "IPA": Isophthalic acid "DMI": Dimethyl isophthalate "P1009": Dimeric acid "Pripol 1009" (manufactured by Croda International)
"TMAn": Trimellitic anhydride "BPEF": Bisphenoxyethanol fluorene "BPE-20": Approximately 2 moles of ethylene oxide adduct of bisphenol A "Nieuport BPE-20" (manufactured by Sanyo Kasei Kogyo Co., Ltd.)
"EG": Ethylene glycol "NPG": Neopentyl glycol "1.4BG": 1.4-butanediol "1.6HG": 1,6-Hexanediol "1.10DG": 1,10-decanediol " P2033 ": Dimerdiol" Pripole 2033 "(manufactured by Croda)

<Hardener>
The following polyepoxy compounds were prepared as curing agents.
-Polyepoxy compound (B-1): Phenolic novolac type epoxy resin "YDPN-638" (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) (WPE = 177 (g / eq))
Polyepoxy compound (B-2): glycidyl ether type special polyfunctional epoxy resin "jER-1031S" (manufactured by Mitsubishi Chemical Corporation) (WPE = 200 (g / eq))
-Polyepoxy compound (B-3): Triglycidyl paraaminophenol "jER-630" (manufactured by Mitsubishi Chemical Corporation) (WPE = 96 (g / eq))

<Manufacturing of adhesive composition>
Using the polyester resin and the curing agent obtained above, an adhesive composition was produced as follows.

(Example 3-1)
The polyester resin (A-1) obtained above is diluted with a mixed solvent of toluene / cyclohexane = 4/1 (weight ratio) to a solid content concentration of 50%, and this polyester resin (A-1) solution (solid content). 10 parts of the polyepoxy compound (B-1) (solid content) was added to 100 parts), and further diluted with a mixed solvent of toluene / cyclohexane = 4/1 (weight ratio) so that the solid content was 50%. , Stirring and mixing to obtain an adhesive composition.

(Examples 3-2 to 3-4, Comparative Examples 3-1 to 3-2)
In Example 3-1 an adhesive composition was obtained in the same manner except that the resin composition was as shown in Table 3-3.
The obtained adhesive composition was evaluated as follows, and the results are shown in Table 3-3.

<Manufacturing of laminated body>
The adhesive composition prepared above was applied to a polyimide film "Kapton 200H" (manufactured by Toray DuPont) having a thickness of 50 μm with an applicator, and then dried at 120 ° C. for 5 minutes to form an adhesive layer having a dry thickness of 25 μm. .. Next, (1) a rolled copper foil having a thickness of 30 μm or (2) a polyimide film “Kapton 200H” having a thickness of 50 μm is laminated with the adhesive layer surface of the polyimide film with an adhesive layer (lamination conditions: 170 ° C., 0.2 MPa, respectively). The feed rate was 1.5 m / min), and then heat treatment and curing were performed in an oven at 160 ° C. for 4 hours to obtain each laminate.
For convenience, the laminate (polyimide film / adhesive layer / rolled copper foil) laminated with the rolled copper foil is referred to as PI / Cu.

[Initial adhesive strength]
The laminate obtained above was cut out to a width of 1 cm and used as a test piece. The test piece was fixed to a glass plate having a thickness of 2 mm using double-sided tape, and the tensile peel strength of the test piece was measured using a peeling tester in an environment of 23 ° C. and 50% RH (peeling speed: 50 mm / min). , Peeling angle: 180 °). The evaluation criteria are as follows.
⊚: 12 N / cm or more ○: 9 N / cm or more, less than 12 N / cm Δ: 6 N / cm or more, less than 9 N / cm ×: less than 6 N / cm

From the results of Tables 3-1 to 3-3 above, the polyester resins (A-1) to (A-8) of Production Examples 3-1 to 3-8 satisfying the requirements of the present invention have a low dielectric constant and a low dielectric constant. The adhesive compositions of Examples 3-1 to 3-4, which are excellent in normal contact, particularly low dielectric loss tangent, and obtained by using them, have initial adhesiveness after curing and long-term durability in a moist heat environment. It is excellent in.
On the other hand, the polyester resin (A'-1) of Comparative Production Example 3-1 is inferior in low dielectric loss tangent, and Comparative Example 3-1 obtained by using it has initial adhesiveness after curing and further under a moist heat environment. It was also inferior in long-term durability. Further, the polyester resin (A'-2) of Comparative Production Example 3-2 was inferior in terms of low dielectric constant and low dielectric loss tangent.

Although the specific embodiment of the present invention has been shown in the above examples, the above examples are merely examples and are not interpreted in a limited manner. Various variations apparent to those skilled in the art are intended to be within the scope of the present invention.

The adhesive composition of the present invention is an adhesive composition containing a polyester resin, and has an effect of being excellent in long-term durability in a moist heat environment and having high adhesiveness. The adhesive composition of the present invention is particularly used for producing an adhesive for producing a metal-plastic laminate, for example, a flexible laminate such as a flexible copper-clad laminate or a flexible printed substrate, a coverlay, or a bonding sheet. It is preferably used for the adhesive used.

Claims

An adhesive composition containing a polyester resin (A1) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A1) satisfies the following requirements. An adhesive composition for a flexible printed wiring board.
[1] The ester bond concentration is 7 mmol / g or less.
[2] The acid value is 3 mgKOH / g or more.
[3] The glass transition temperature (Tg) is -5 ° C or higher.
The polyester resin (A1) contains aromatic polyvalent carboxylic acids as polyvalent carboxylic acids, and the content of the aromatic polyvalent carboxylic acids as a whole is 25 mol% or more. The adhesive composition for a flexible printed wiring board according to claim 1.
The adhesive composition for a flexible printed wiring board according to claim 1 or 2, wherein the polyester resin (A1) has a carboxy group in the side chain.
The polyester resin (A1) contains at least one selected from the group consisting of dimer acids as the polyhydric carboxylic acids and dimer diols as the polyhydric alcohols, and the dimer for the entire polyvalent carboxylic acids. Claims 1 to 3 characterized in that the total content (α + β) of the acid content (α) and the dimerdiol content (β) with respect to the total polyhydric alcohols is 5 mol% or more. The adhesive composition for a flexible printed wiring board according to any one of the above.
The polyester resin (A1) contains a bisphenol skeleton-containing monomer as the polyhydric alcohols, and the content of the bisphenol skeleton-containing monomer with respect to the entire polyhydric alcohols is 10 mol% or more. The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 4.
An adhesive composition containing a polyester resin (A2) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A2) satisfies the following requirements. An adhesive composition for a flexible printed wiring board.
[I] The above-mentioned multivalent carboxylic acids contain 25 mol% or more of aromatic polyvalent carboxylic acids.
[II] The above-mentioned multivalent carboxylic acids contain trivalent or higher valent carboxylic acids (x1) having an acid anhydride radix of 0 or 1.
[III] The ester bond concentration is 7 mmol / g or less.
[IV] The acid value is 3 mgKOH / g or more.
The adhesive composition for a flexible printed wiring board according to claim 6, wherein the polyester resin (A2) has a glass transition temperature of −5 ° C. or higher.
The flexible printed wiring board according to claim 6 or 7, wherein the polyester resin (A2) is a polyester resin obtained through a step of depolymerization using polyvalent carboxylic acids (x1). Adhesive composition for.
The polyester resin (A2) contains at least one selected from the group consisting of dimer acids as the polyhydric carboxylic acids and dimer diols as the polyhydric alcohols, and the dimer acids with respect to the entire polyhydric carboxylic acids. 6-8, wherein the total content (α + β) of the content (α) of the dimerdiol and the content (β) of the dimerdiol with respect to the total polyhydric alcohol is 5 mol% or more. The adhesive composition for a flexible printed wiring board according to any one of the items.
The polyester resin (A2) contains a bisphenol skeleton-containing monomer as the polyhydric alcohols, and the content of the bisphenol skeleton-containing monomer with respect to the entire polyhydric alcohols is 10 mol% or more. The adhesive composition for a flexible printed wiring board according to any one of claims 6 to 9.
An adhesive composition containing a polyester resin (A3) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A3) has a glass transition temperature (Tg). ) −5 ° C. or higher, a temperature of 23 ° C., and a dielectric positive contact (α) of 0.005 or lower at 10 GHz under a relative humidity of 50% RH environment.
An adhesive composition containing a polyester resin (A4) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A4) has an acid value of 3 mgKOH / g. As described above, the adhesive composition for a flexible printed wiring board is characterized by having a dielectric positive contact (α) of 0.005 or less at 10 GHz under a temperature of 23 ° C. and a relative humidity of 50% RH.
An adhesive composition containing a polyester resin (A5) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A5) has a glass transition temperature (Tg). ) -5 ° C or higher, acid value 3 mgKOH / g or higher, temperature 23 ° C, relative humidity 50% Adhesive for flexible printed wiring board characterized by dielectric constant (α) 0.005 or lower at 10 GHz under RH environment. Agent composition.
An adhesive composition containing a polyester resin (A6) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A6) has a relative temperature of 23 ° C. An adhesive composition for a flexible printed wiring board, which has a dielectric loss tangent (α) of 0.003 or less at 10 GHz under a humidity of 50% RH environment.
The adhesive composition for a flexible printed wiring board according to any one of claims 1 to 14, further containing a polyepoxy compound (B).
An adhesive for a flexible printed wiring board according to any one of claims 1 to 15, wherein the adhesive composition for a flexible printed wiring board is cured.
A flexible printed wiring board characterized by using the adhesive for a flexible printed wiring board according to claim 16.
An adhesive composition containing a polyester resin (A1) containing a structural unit derived from polyvalent carboxylic acids and a structural unit derived from polyhydric alcohols, wherein the polyester resin (A1) satisfies the following requirements. However, the adhesive composition is characterized in that the content of the polyester resin (A1) in the polyester resin is more than 50% by weight.
[1] The ester bond concentration is 7 mmol / g or less.
[2] The acid value is 3 mgKOH / g or more.
[3] The glass transition temperature (Tg) is -5 ° C or higher.