JP7211403B2 - Adhesive composition and adhesive - Google Patents

Description

The present invention relates to an adhesive composition containing a polyester resin and an adhesive obtained by curing this adhesive composition, more specifically, low moisture absorption, tack-free property before curing, initial adhesiveness after curing Furthermore, the present invention relates to an adhesive composition excellent in long-term durability in a moist and hot environment and an adhesive obtained by curing this adhesive composition.

Conventionally, polyester resins are excellent in heat resistance, chemical resistance, durability, and mechanical strength, so they are used in a wide range of applications such as films, PET bottles, fibers, toners, electrical parts, adhesives, and pressure sensitive adhesives. ing. In addition, polyester-based resins have high polarity due to their polymer structure, so they exhibit excellent adhesion to polar polymers such as polyester, polyvinyl chloride, polyimide, and epoxy resins, as well as metal materials such as copper and aluminum. It has been known. Utilizing this characteristic, use as an adhesive for producing a laminate of metal and plastic, for example, an adhesive for producing a flexible copper-clad laminate, a flexible printed circuit board, etc., has been investigated.

For example, Patent Document 1 discloses a thermosetting adhesive sheet which is excellent in dimensional stability when cured and excellent in adhesiveness, heat resistance, flexibility, electrical insulation, low dielectric constant and low dielectric loss tangent after curing. For the purpose, the total amount of a reactive functional group capable of reacting with at least one of an organometallic compound or an epoxy group-containing compound and a functional group having a heteroatom other than halogen is 0.01 mmol / g or more, 9 mmol / A thermosetting composition has been proposed which contains a resin (eg, a polyester resin) having a molecular weight of 10 g or less, an organometallic compound, and a trifunctional or higher epoxy group-containing compound.

Further, in Patent Document 2, for the purpose of obtaining an adhesive composition containing a polyester resin having excellent resistance to moist heat and cationic acid, and having both compatibility and adhesiveness with an epoxy resin, aromatic dicarboxylic acid An adhesive composition containing an acid component, a polyester resin composed of dimer diol, a specific glycol, a glycol having a specific structure or an oxyacid, and an alkylene glycol having 2 to 10 carbon atoms has been proposed.

Japanese Unexamined Patent Application Publication No. 2017-031301 JP 2003-183365 A

However, in recent years, in addition to curability, heat resistance, and initial adhesiveness, tack-free properties are also required from the viewpoint of rework as physical properties required for adhesive layers such as flexible copper-clad laminates and flexible printed circuit boards. From this point of view, low hygroscopicity and long-term durability in moist and heat environments are also strongly required.

For example, in the technology disclosed in Patent Document 1, a large amount of polyhydric 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, which results in glass There are problems such as deterioration in initial adhesiveness due to a decrease in transition temperature and difficulty in reworking due to tack. In addition, Patent Document 1 does not take into account long-term durability in a hot and humid environment, and further improvement is required.

In addition, when a copper clad laminate or the like is produced using the adhesive composition disclosed in Patent Document 2, although it is relatively excellent in moist heat resistance and low hygroscopicity, the glass transition temperature is too low, resulting in polyimide and There are problems such as insufficient adhesion to copper and occurrence of tack. In addition, since it contains an ether bond-containing glycol such as polypropylene glycol, or does not have an acid value that acts as a reaction point with the epoxy resin, there is also the problem of poor heat resistance, and further improvement is required. .

Therefore, in view of this background, the present invention provides an adhesive composition having low moisture absorption, tack-free property before curing, initial adhesion after curing, and further excellent long-term durability in a hot and humid environment, and the adhesion thereof. An object of the present invention is to provide an adhesive in which an agent composition is cured.

However, as a result of intensive research in view of such circumstances, the present inventors have found that an adhesive composition containing a polyester resin has a glass transition temperature (Tg) while reducing the ester bond concentration of the polyester resin. Adhesive composition with low hygroscopicity, tack-free property before curing, initial adhesiveness after curing, and long-term durability in a moist and heat environment by increasing the acid value and giving it a predetermined value or more. He found that it can be a product and completed the present invention.

That is, the gist of the present invention is an adhesive composition containing a polyester resin (A) containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, wherein the polyester resin (A) The adhesive composition has an ester bond concentration of 7 mmol/g or less, an acid value of 3 mgKOH/g or more, and a glass transition temperature (Tg) of −5° C. or more.

The present invention also provides an adhesive obtained by curing the above adhesive composition.

As described with respect to Patent Document 1 above, a large amount of polyhydric carboxylic acid or polyhydric alcohol having a long-chain alkyl group is usually used in order to reduce the water absorption, but on the other hand, initial adhesiveness and tack-free property , and the long-term durability in a wet-heat environment is lowered.
By optimizing the ester bond concentration, acid value, and glass transition temperature (Tg) by adjusting the composition of the monomers that make up the polyester resin, the inventors have found that while having low hygroscopicity, The present inventors have completed the present invention based on the discovery of excellent tack-free properties, initial adhesive properties after curing, and long-term durability in a moist and hot environment.

The adhesive composition of the present invention is an adhesive composition containing a polyester resin, and has low moisture absorption, tack-free property before curing, initial adhesion after curing, and long-term durability in a moist and heat environment. Especially adhesives for producing laminates of metal and plastic, for example, flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards, coverlays, bonding sheets, etc. Effective for adhesives used in

The configuration of the present invention will be described in detail below, but these are examples of preferred embodiments.
In the present invention, the term "class" attached after the name of a compound is a concept that includes not only the compound, but also derivatives of the compound. For example, the term "carboxylic acids" includes carboxylic acids as well as carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides and carboxylic acid esters.

The adhesive composition of the present invention contains at least a polyester resin (A) containing structural units derived from polyhydric carboxylic acids and structural units derived from polyhydric alcohols. First, the polyester-based resin (A) will be described.

<Polyester resin (A)>
The polyester-based resin (A) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and preferably the polyhydric carboxylic acid and the polyhydric alcohol are linked by an ester bond. It is obtained by letting

[Polyvalent carboxylic acids]
Polyvalent carboxylic acids in polyvalent carboxylic acids include, for example, aromatic polyvalent carboxylic acids described later; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and acid anhydrides thereof alicyclic polyvalent carboxylic acids such as polycarboxylic acids; and aliphatic polyvalent carboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid. 1 type(s) or 2 or more types can be used for polyhydric carboxylic acid.

It is preferable to contain aromatic polyvalent carboxylic acids as polyvalent carboxylic acids. Examples of aromatic polycarboxylic 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). Aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are also included. Furthermore, trifunctional or higher functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton or acid value to the polyester resin (A) are also included in the above aromatic polyvalent carboxylic acids. Examples of aromatic carboxylic acids in trifunctional or higher aromatic carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), and trimellitic anhydride. product, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride , 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2′-bis[(dicarboxyphenoxy)phenyl ] propane dianhydride and the like.
Among these, aromatic dicarboxylic acids are preferred, terephthalic acid and isophthalic acid are particularly preferred, and isophthalic acid is more preferred.

The content of aromatic polycarboxylic acids relative to the total polycarboxylic acids is preferably 25 mol% or more, more preferably 40 mol% or more, particularly preferably 70 mol% or more, and still more preferably 90 mol% or more. is. Aromatic polycarboxylic acids may occupy 100 mol %. If the content of the aromatic carboxylic acid is too low, the long-term durability in a moist and hot environment tends to be insufficient.

The content (molar ratio) of the aromatic polycarboxylic acid relative to the total polycarboxylic acid is obtained from the following formula.
Aromatic acid content (mol%) = (aromatic polycarboxylic acids (mol)/polycarboxylic acids (mol)) x 100

In addition, aromatic dicarboxylic acids having a sulfonic acid group such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5(4-sulfophenoxy)isophthalic acid, etc. , and aromatic dicarboxylates having sulfonic acid groups such as metal salts and ammonium salts thereof, from the viewpoint of the hygroscopicity of the polyester resin (A), the content of the total polycarboxylic acids is 10 mol% or less. 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 %.

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

Examples of bisphenol skeleton-containing monomers include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,4′-dihydroxybenzophenone, bisphenol fluorene, and Hydrogenated products thereof, and glycols such as ethylene oxide adducts and propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to hydroxyl groups of bisphenols can be mentioned. Among them, those containing a bisphenol A skeleton are preferable, and ethylene oxide adducts are preferable from the viewpoint of reactivity. In particular, 2 to 3 mol of ethylene oxide is added from the viewpoint of heat resistance, low moisture absorption, and long-term durability in moist and heat environments. things are preferred.

The content of the bisphenol skeleton-containing monomer relative to the total polyhydric alcohol is preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 30 mol% or more, and still more preferably 40 mol% or more. . If the content of the bisphenol skeleton-containing monomer is too low, there is a tendency that the low hygroscopicity and the long-term durability in a moist and heat environment become insufficient.
In addition, the upper limit of the content of the bisphenol skeleton-containing monomer with respect to the entire polyhydric alcohol is 100 mol %.

Examples of aliphatic polyhydric alcohols 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, dimethylolheptane, 2,2,4 -trimethyl-1,3-pentanediol and the like.

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

Examples of aromatic polyhydric alcohols include para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, and ethylene oxide adducts of 1,4-phenylene glycol.

Diethylene glycol, triethylene glycol, dipropylene glycol, and further, ether bond-containing glycols other than bisphenol skeleton-containing monomers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol have heat resistance, low hygroscopicity, and moist heat. From the viewpoint of long-term durability in the environment, the content relative to the entire polyester resin is preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, and still more preferably 8% by weight. % or less, and most preferably 5 wt % or less.

[Overall raw material compounds constituting the polyester resin (A)]
The compound constituting the polyester-based resin (A) may contain dimer acids as polyvalent carboxylic acids, and dimer diols as polyhydric alcohols regardless of whether or not they contain dimer acids. may contain.
The compound constituting the polyester resin (A) in the present invention preferably contains at least one selected from the group consisting of dimer acids as polycarboxylic acids and dimer diols as polyhydric alcohols.
Examples of dimer acids and dimer diols include dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc., and dimers, which are reductants of these. diols, hydrogenated products thereof, and the like. Among them, hydrogenated products are preferred from the viewpoint of suppressing gelation during production, and dimer diols are preferred from the viewpoint of increasing the content ratio of the aromatic acid in the polyvalent carboxylic acid component, and hydrogenated dimers are particularly preferred. They are diols.

The total content (α + β) (mol%) of the dimer acid content (α) relative to the total polyhydric carboxylic acids and the dimer diol content (β) relative to the total polyhydric alcohols is 5 mol% or more. more preferably 10 mol % or more, particularly preferably 15 mol % or more, and 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, and still more preferably 55 mol% or less.
If the total content (α + β) (mol%) of dimer acids and dimer diols is too small, low hygroscopicity and long-term durability in a moist heat environment tend to be insufficient, and the total content (α + β) ( %), the tack-free property before curing and the initial adhesive property after curing tend to be insufficient.

In addition, the ratio of the content (β) of dimer diols to the total content (α + β) of dimer acids and dimer diols ((β)/(α + β) (molar ratio)) is 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 dimer diols relative to the total content (α + β) of dimer acids and dimer diols is too low, long-term durability in wet and heat environments tends to be insufficient.

The total content (α + β) (% by weight) of the dimer acid content (α) and the dimer diol content (β) relative to the entire polyester resin (A) is preferably 10% by weight or more, more preferably. is 15% by weight or more, particularly preferably 20% by weight or more, more preferably 30% by weight or more, and the total content (α + β) (% by weight) is preferably 80% by weight or less, more preferably 70% by weight or less, particularly preferably 60% by weight or less, more preferably 50% by weight or less.

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

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 (A). Examples of such oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, 4,4-bis( and p-hydroxyphenyl)valeric acid.

In the polyester-based resin (A) used in the present invention, in addition to the polycarboxylic acid anhydride to be described later, for the purpose of introducing a branched skeleton as necessary, tri- or more functional polycarboxylic acids, and At least one selected from the group consisting of tri- 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 points) of the resin, and a strong coating film with a high crosslink density can be obtained.

In that case, trifunctional or higher polyvalent carboxylic acids include, for example, trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-diphenyltetracarboxylic dianhydride, 3 ,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2′-bis[(dicarboxyphenoxy)phenyl]propane Examples include compounds such as dianhydrides. Examples of tri- or higher functional polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.
Tri- or more functional polycarboxylic acids and tri- or more functional polyhydric alcohols may be used alone or in combination of two or more.

When using at least one selected from the group consisting of trifunctional or higher polycarboxylic acids and trifunctional or higher polyhydric alcohols separately from the polycarboxylic anhydride described later, the entire polycarboxylic acid The content of trifunctional or higher polyhydric carboxylic acids or the content of trifunctional or higher polyhydric alcohols with respect to the total polyhydric alcohols is preferably 0.1 to 5 mol%, more preferably 0.1 It is in the range of ~3 mol%. If the content of either or both is too high, the coating film formed by applying the adhesive tends to have reduced mechanical properties such as elongation at break, and gelation tends to occur during polymerization. .

The polyester-based resin (A) in the present invention preferably has a carboxyl group in its side chain from the viewpoint of curing speed and heat resistance after curing. Such a polyester-based resin (A) contains a polyvalent carboxylic anhydride having a carboxylic anhydride structure as a polyvalent carboxylic acid (hereinafter sometimes simply referred to as "polyvalent carboxylic anhydride"). It is obtained by copolymerizing copolymer components.

The polyvalent carboxylic acid anhydride preferably has at least two carboxylic acid anhydride structures for the purpose of introducing carboxy groups into side chains. dianhydride (pyromellitic dianhydride), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 4,4-oxydiphthalic dianhydride, 2,3,6,7-naphthalene tetra carboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, ethylene glycol bistrimellitate dianhydride, 3,3′,4,4′-diphenyltetracarboxylic dianhydride, 2 ,2′,3,3′-diphenylsulfonetetracarboxylic anhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride and other aromatic polycarboxylic acid anhydrides;
1,2,3,4-cyclobutanetetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5-(2 alicyclic polyvalent carboxylic anhydrides such as ,5-dioxotetrahydrofuryl)-3-cyclohexene-1,2-dicarboxylic anhydride and cyclopentanetetracarboxylic dianhydride;
Aliphatic polyvalent carboxylic anhydrides such as ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, and 1,2,3,4-pentanetetracarboxylic dianhydride;
etc. One kind selected from these can be used alone, or two or more kinds can be used in combination.

Among these polyvalent carboxylic acid anhydrides, the polymerization reactivity when producing the polyester resin (A), the heat resistance of the produced polyester resin (A), and the long-term durability in a moist and hot environment From, preferably an aromatic polycarboxylic acid anhydride, more preferably 1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride), 2,3,6,7- naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, and 3,3′,4,4′-diphenyltetracarboxylic dianhydride, particularly preferably 1,2 , 4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride).

The content of the polycarboxylic acid anhydride in the polycarboxylic acids is preferably 0.5 to 20 mol%, more preferably 1 to 15 mol%, particularly preferably 2, based on the total polycarboxylic acids. to 10 mol %, more preferably 3 to 8 mol %. If the content is too small, the heat resistance tends to be insufficient, and if the content is too large, gelation occurs during the production process of the polyester resin (A), and low hygroscopicity or under a moist heat environment. Long-term durability tends to be insufficient.

[Production of polyester resin (A)]
The polyester resin (A) used in the present invention can be produced by a well-known method. to obtain a polyester-based resin, and further introducing an acid value.

As a method of introducing an acid value into a polyester-based resin, for example, a method of introducing a carboxylic acid into the resin by acid addition after an esterification reaction or after reduced-pressure polycondensation can be mentioned. When a monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compound is used for acid addition, the molecular weight may decrease due to transesterification, so it is preferable to use a compound having at least one carboxylic acid anhydride. Examples of acid anhydrides include succinic anhydride, maleic anhydride, orthophthalic anhydride, 2,5-norbornenedicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, and oxydiphthalic anhydride. acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4' -diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride, etc. mentioned.

When the total amount of polyvalent carboxylic acids constituting the polyester-based resin (A) is 100 mol %, if 15 mol % or more of acid addition is performed, gelation may occur, and the polyester may be depolymerized, resulting in the loss of the resin. Molecular weight may decrease. Methods of acid addition include a method of direct addition in a bulk state and a method of solution addition of the polyester. The reaction in the bulk state is fast, but if a large amount is added, gelation may occur and the reaction will be at a high temperature, so it is necessary to take precautions such as blocking oxygen gas to prevent oxidation. On the other hand, addition in a solution state is slow in reaction, but can stably introduce a large amount of carboxyl groups.

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

[Ester bond concentration of polyester resin (A)]
The polyester resin (A) used in the present invention has an ester bond concentration of 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, more preferably 3.1 to 5 mmol/g.
If the ester bond concentration is too high, low hygroscopicity and long-term durability in a moist and heat environment will be insufficient. On the other hand, if the ester bond concentration is too low, the initial adhesiveness will be insufficient.

The definition and measuring 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-based resin, and is obtained, for example, by a calculated value from the charged amount. This calculation method is a value obtained by dividing the number of moles of the smaller of the charged amounts of the polyhydric carboxylic acid and the polyhydric alcohol by the total weight of the resin, and an example of the calculation formula is shown below.
When the polyhydric carboxylic acid and the polyhydric alcohol are charged in the same molar amount, either of the following formulas may be used.
Moreover, when using a monomer having both a carboxy group and a hydroxyl group, or when producing a polyester from caprolactone or the like, the calculation method will be changed as appropriate.

(When polyhydric carboxylic acids are less than polyhydric alcohols)
Ester group concentration (mmol/g)=[(A1/a1×m1+A2/a2×m2+A3/a3×m3 . . . )/Z]×1000
A: Charge amount (g) of polyvalent carboxylic acid
a: molecular weight of polyvalent carboxylic acid m: number of carboxylic acid groups per molecule of polyvalent carboxylic acid Z: finished weight (g)

(When polyhydric alcohols are less than polyhydric carboxylic acids)
Ester group concentration (mmol/g) = [(B1/b1 x n1 + B2/b2 x n2 + B3/b3 x n3...)/Z] x 1000
B: Charged amount of polyhydric alcohol (g)
b: molecular weight of polyhydric alcohol n: number of hydroxyl groups per molecule of polyhydric alcohol Z: finished weight (g)

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

In addition, the concentration of polar groups other than ester bonds and reactive functional groups is preferably low from the viewpoint of low hygroscopicity and long-term durability in wet and heat environments.
Other polar groups include, for example, amide groups, imide groups, urethane groups, urea groups, ether groups, carbonate groups and the like.

The total concentration of amide groups, imide groups, urethane groups, and urea groups is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, and still more preferably is less than or equal to 0.5 mmol/g, most preferably less than or equal to 0.2 mmol/g.
Examples of the ether group include an alkyl ether group and a phenyl ether group, and from the viewpoint of low hygroscopicity and long-term durability in a moist and heat environment, it is particularly preferable to lower the concentration of the alkyl ether group.
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 preferably 1 mmol/g or less. Preferably, it is 0.5 mmol/g or less. In addition, 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 less than or equal to 0.2 mmol/g.

[Acid value of polyester resin (A)]
The acid value of the polyester resin (A) 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, further preferably 7 to 20 mg KOH/g.
If the acid value is too low and the polyepoxy compound (B) is included in the adhesive composition, the degree of cross-linking with the polyepoxy compound (B) will be insufficient, resulting in poor heat resistance. be sufficient. On the other hand, if the acid value is too high, the hygroscopicity and long-term durability in a hot and humid environment are lowered, and a large amount of the polyepoxy compound (B) is required for curing. It tends to be inferior in dielectric properties.

The definition and measuring method of the acid value are as follows.
The acid value (mgKOH/g) can be obtained 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 performing neutralization titration based on JIS K0070. can.
In the present invention, the acid value of the polyester resin (A) is due to the content of carboxy groups in the resin.

[Glass transition temperature (Tg) of polyester resin (A)]
The glass transition temperature (Tg) of the polyester resin (A) 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 It is preferably 7-40°C, most preferably 10-30°C.
If the glass transition temperature (Tg) is too low, initial adhesiveness and tack-free properties will be insufficient. On the other hand, 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 obtained by measuring with a differential scanning calorimeter. The measurement conditions are a measurement temperature range of -70 to 140°C and a temperature increase rate of 10°C/min.

[Peak top molecular weight (Mp) and weight average molecular weight (Mw) of polyester resin (A)]
The peak top molecular weight (Mp) of the polyester resin (A) used in the present invention is preferably 5,000 to 150,000, more preferably 10,000 to 100,000, particularly preferably 15,000 to 70,000, and still 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, and flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards will be produced. There is a tendency that problems such as the polyester-based resin of the adhesive layer flowing and oozing out during press processing when bonding are likely to occur. On the other hand, if the peak top molecular weight (Mp) is too high, the initial adhesion tends to be insufficient, or the viscosity of the solution during coating is too high, making it difficult to obtain a uniform coating film.

The weight average molecular weight (Mw) of the polyester resin (A) used in the present invention is preferably 5,000 to 300,000, more preferably 10,000 to 200,000, particularly preferably 20,000 to 150,000, and still 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, and flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards will be produced. There is a tendency that problems such as the polyester-based resin of the adhesive layer flowing and oozing out during press processing when bonding are likely to occur. On the other hand, if the weight-average molecular weight (Mw) is too high, the initial adhesion tends to be insufficient, or the viscosity of the solution during coating is too high, making it difficult to obtain a uniform coating film.

Methods for measuring peak top molecular weight (Mp) and weight average molecular weight (Mw) are as follows.
The peak top molecular weight (Mp) and weight average molecular weight (Mw) were determined by high performance liquid chromatography (manufactured by Tosoh Corporation, "HLC-8320GPC") using a column (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 ⁶ , theoretical Number of plates: 16,000 plates/line, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm)))))), and can be obtained by standard polystyrene molecular weight conversion.

[Water absorption rate (% by weight) of polyester resin (A)]
The water absorption rate of the polyester resin (A) 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, and further preferably 0.6% by weight or less. be.
If the water absorption is too high, the wet heat durability and insulation reliability tend to deteriorate, and the dielectric properties tend to deteriorate. Inferior in dielectric properties means that the relative permittivity and dielectric loss tangent values do not decrease or increase.

The method for measuring water absorption 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 polyester resin layer with a dry film thickness of 65 μm. This sheet was cut into a size of 7.5 cm×11 cm, the polyester-based resin layer surface of the sheet was laminated on a glass plate, and then the release film was peeled off. By repeating this operation six times, a test plate having a polyester-based resin layer with a thickness of 390 μm on a glass plate is obtained.
After immersing the thus-obtained test plate in purified water at 23°C for 24 hours, it is taken out, the water on the surface is wiped off, and dried at 70°C for 2 hours. The weight required in each of these steps is measured, and the water absorption (% by weight) is calculated from the change in weight according to the following formula.
(c−d)×100/(b−a)
a: Weight of the glass plate alone b: Weight of the initial test plate c: Weight of the test plate immediately after removing from the purified water and wiping off moisture d: Weight of the test plate after drying at 70 ° C. for 2 hours

Further, in the present invention, the content of the polyester resin (A) in the polyester resin in the adhesive composition is preferably more than 50% by weight, more preferably 70% by weight of the total polyester resin. It is at least 85% by weight, particularly preferably at least 85% by weight. If the content is too small, low hygroscopicity and long-term durability in wet and heat environments tend to be insufficient.

<Polyepoxy compound (B)>
The adhesive composition of the present invention preferably further contains a polyepoxy compound (B). By reacting and curing the epoxy groups in the polyepoxy compound (B) and the carboxyl groups in the polyester resin (A), an adhesive layer with excellent heat resistance and not only adhesive strength but also excellent solder heat resistance is formed. Obtainable.

Examples of the polyepoxy compound (B) used in the present invention include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether; phenol novolak glycidyl ether, cresol novolak. 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-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil alicyclic or aliphatic epoxides such as Polyepoxy compound (B) can be used alone or in combination of two or more.

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 can be formed by heating at a relatively low temperature. There is a tendency that the coating film of the object can be B-staged (semi-cured state), and the fluidity of the B-stage film can be suppressed to improve the workability in the bonding operation. Moreover, the effect of suppressing the foaming of the B-stage film can be expected, which is preferable.

Examples of nitrogen atom-containing polyepoxy compounds include glycidylamines such as tetraglycidyldiaminodiphenylmethane, triglycidyl para-aminophenol, tetraglycidylbisaminomethylcyclohexanone, and N,N,N',N'-tetraglycidyl-m-xylenediamine. system and the like.

When the adhesive composition of the present invention contains a polyepoxy compound (B) and the polyepoxy compound (B) further contains these nitrogen atom-containing polyepoxy compounds, such nitrogen atom-containing polyepoxy compounds 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 polyepoxy compound (B).
In addition, 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 with respect to 100 parts by weight of the polyester resin (A). Part by weight or less.
If the content of the nitrogen atom-containing polyepoxy-based compound is too high, the rigidity tends to be excessively high, and the adhesiveness tends to decrease. tend to

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

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

<Adhesive composition>
The adhesive composition of the present invention contains at least a polyester resin (A), preferably further contains a polyepoxy compound (B), has low moisture absorption, tack-free properties before curing, and initial It has the effect of being excellent in adhesiveness and long-term durability in a wet and hot environment.

In the adhesive composition of the present invention, fillers, flame retardants, etc. may be blended. In that case, the content of the polyester resin (A) in the adhesive composition should be Considering the total solid content, it is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, and still more preferably 60 to 85% by weight.

When the adhesive composition of the present invention contains the polyepoxy compound (B), the content of the polyepoxy compound (B) is preferably 1 part per 100 parts by weight of the polyester resin (A). ~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-based compound (B) is too small, the heat resistance and long-term durability in a hot and humid environment tend to be insufficient. , the dielectric properties tend to be inferior.

A solvent may be added to the adhesive composition of the present invention in order to appropriately adjust the viscosity of the adhesive composition and to 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 solvents 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; amides such as dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; aromatics such as toluene and xylene, and the like. The solvents listed above may be used alone, or two or more of them may be mixed and used in any combination and ratio.

[Other ingredients]
The adhesive composition of the present invention may contain components other than those listed above for the purpose of further improving its functionality. Other components include, for example, inorganic fillers, coupling agents such as silane coupling agents, UV inhibitors, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, elastic softening agents, diluents, agents, antifoaming 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 adhesive composition, and exhibits effects of excellent initial adhesiveness, low hygroscopicity, and long-term durability under moist and heat environments.
"Curing" in the present invention means intentionally curing the adhesive composition with heat and/or light, etc., 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, which is preferably 50% or more, more preferably 60% or more, particularly preferably 70% or more, and still more preferably 75% or more. If the gel fraction is too low, the heat resistance and long-term durability in a moist and hot environment tend to be insufficient.
The gel fraction mentioned above means the weight percentage of the undissolved adhesive component with respect to the weight of the adhesive before immersion after immersing the adhesive in methyl ethyl ketone at 23° C. for 24 hours.

When the adhesive composition of the present invention is cured or semi-cured to form an adhesive, the curing method of the adhesive composition varies depending on the ingredients and amounts in the adhesive composition, but is usually 80 to 200°C. 10 minutes to 10 hours at .

A catalyst may be used when curing the adhesive composition of the present invention using the polyepoxy compound (B).
Examples of such catalysts include 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)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; octylic acid, quaternary tetraphenylborate salt, etc., converted into amine salt; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diallyiodonium hexafluoroantimonate; and triphenylphosphine. Among these, 1,8-diazabicyclo(5,4,0)-undecene-7 and 1,5-diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5 ,4,0)-undecene-7 and other tertiary amines; and compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternary tetraphenylborate salts, etc., are thermosetting and heat-resistant. It is preferable in terms of properties, adhesion to metals, and storage stability after compounding.
In this case, the blending amount is preferably 0.01 to 1 part by weight per 100 parts by weight of the polyester resin (A). Within this range, the catalytic effect on the reaction between the polyester-based resin (A) and the polyepoxy-based compound (B) is further increased, and strong adhesion 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 and heat environment, it is effective in bonding substrates made of various materials such as resins and metals. It is suitable as an adhesive for producing a laminate with a plastic layer, for example, as an adhesive used for bonding electronic material members.
Examples of "electronic material members" in the present invention include flexible printed circuit boards, coverlays, bonding sheets, and the like.
Flexible laminates, such as flexible copper-clad laminates and flexible printed circuit boards, are examples of materials produced by laminating electronic material members. A flexible laminate is, for example, a laminate obtained by sequentially laminating "flexible flexible substrate/adhesive layer/conductive metal layer made of copper, aluminum, alloys thereof, etc.", and constitutes the adhesive layer. The adhesive of the present invention can be used as an adhesive. In addition to the various layers described above, the flexible laminate may further include other insulating layers, other adhesive layers, and other conductive metal layers.

EXAMPLES 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 thereof is not exceeded. In addition, "parts" and "%" in the examples mean weight standards.

Proportion (mol%) of aromatic polycarboxylic acids to the total polycarboxylic acids (referred to as "aromatic acid content" in Table 1), ester bond concentration (mmol/g), water absorption, glass transition temperature ( ° C.), acid value (mgKOH/g), peak top molecular weight (Mp), weight average molecular weight (Mw), equivalent weight of epoxy groups to COOH were measured according to the description of this specification.

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

[Production Example 1: Production of polyester resin (A-1)]
A thermometer, a stirrer, a rectifying column, and a reactor equipped with a nitrogen inlet tube were charged with 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as a polyhydric carboxylic acid and ethylene of bisphenol A as a polyhydric alcohol. Oxide about 2 mol adduct "Newpol BPE-20" (BPE-20) (manufactured by Sanyo Chemical Industries, Ltd.) 223.9 parts (0.6868 mol), neopentyl glycol (NPG) 28.6 parts (0.2746 mol), 254.4 parts (0.4801 mol) of dimer diol "PRIPOL 2033" (P2033) (manufactured by Croda Co., Ltd.), and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the internal temperature reached 270°C for 120 minutes. The temperature was raised over a period of 3 hours, and an esterification reaction was carried out at 270°C for 3 hours.
Next, the internal temperature is lowered to 200 ° C., 15.0 parts (0.0688 mol) of pyromellitic dianhydride (PMAn) is added and an addition reaction is performed at 200 ° C. for 2 hours. A polyester resin (A-1) having various physical properties was obtained.

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

Table 1 shows the resin composition (structural units derived from components) and physical properties of the obtained polyester resin. In addition, in Table 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" : About 2 mol of ethylene oxide adduct of bisphenol A "Newpol BPE-20" (manufactured by Sanyo Chemical Industries, Ltd.)
"P2033": dimer diol "Pripol 2033" (manufactured by Croda)

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

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

(Example 1)
The polyester resin (A-1) obtained above was diluted with methyl ethyl ketone to a solid content concentration of 60%, and this polyester resin (A-1) solution (100 parts as solid content) was added with a polyepoxy compound ( 10 parts of B-1) (solid content) were blended, diluted with methyl ethyl ketone to a solid content of 50%, stirred and mixed to obtain an adhesive composition.

(Examples 2-3, Comparative Examples 1-5)
An adhesive composition was obtained in the same manner as in Example 1, except that the resin composition was as shown in Table 2.
The obtained adhesive compositions were evaluated as follows. Table 2 shows the results.

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

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

[Wet heat durability]
Put the PI/Cu test piece in a thermo-hygrostat at 85° C. and 85% RH, take it out after a predetermined time, leave it overnight in an environment of 23° C. and 50% RH, and then perform the same initial adhesive strength as described above. to measure the tensile peel strength. The percentage of the adhesive strength after wet heat treatment to the initial adhesive strength was defined as "retention rate".
The absolute value of adhesive strength was evaluated using the same evaluation criteria as those for the initial adhesive strength.
The adhesive force retention rate was evaluated based on the following evaluation criteria.
◎: retention rate of 80% or more ○: retention rate of 60% or more and less than 80% △: retention rate of 40% or more and less than 60% ×: retention rate of less than 40%

[Tack-free property]
The adhesive layer surface of the obtained polyimide film with an adhesive layer before curing was lightly touched with a finger and evaluated based on the following evaluation criteria.
(double-circle): Almost no stickiness is felt.
◯: Not much stickiness is felt.
Δ: Slightly sticky.
x: Sticks to fingers.

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

From the results in Tables 1 and 2 above, the polyester resins (A-1) and (A-2) of Production Examples 1 and 2 that satisfy the requirements of the present invention are excellent in low hygroscopicity, and the performance obtained using them The adhesive compositions of Examples 1 to 3 are excellent in tack-free property before curing, initial adhesive property after curing, and long-term durability in a moist and hot environment.
On the other hand, the polyester resin (A'-1) of Comparative Production Example 1, which has a high ester bond concentration, has high hygroscopicity, and Comparative Examples 1 and 2 obtained using it are inferior in long-term durability in a moist and heat environment. It was something. Likewise, the adhesive compositions of Comparative Examples 3 and 4 obtained using the polyester-based resin (A'-2) of Comparative Production Example 2 having a high ester bond concentration are also inferior in long-term durability in a moist and hot environment. Met.
In addition, the adhesive composition of Comparative Example 5 obtained using the polyester resin (A'-3) of Comparative Production Example 3 having a low glass transition temperature has tack-free properties before curing and initial adhesiveness after curing. was inferior to

The adhesive composition of the present invention is an adhesive composition containing a polyester resin, and has low moisture absorption, tack-free property before curing, initial adhesion after curing, and long-term durability in a moist and heat environment. In particular, it is effective as an adhesive for producing metal and plastic laminates, for example, as an adhesive used for flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards. be.

Claims (8)

An adhesive composition containing a polyester resin (A) containing structural units derived from polyhydric carboxylic acids and structural units derived from polyhydric alcohols,
It contains at least one selected from the group consisting of dimer acids as the polycarboxylic acids and dimer diols as the polyhydric alcohols, and the content (α) of the dimer acids with respect to the entire polyhydric carboxylic acids and the The total content (α + β) with the content (β) of the dimer diols with respect to the entire polyhydric alcohol is 5 mol% or more,
Aromatic polycarboxylic acids are contained as the polycarboxylic acids, and the content of the aromatic polycarboxylic acids with respect to the total polycarboxylic acids is 25 mol% or more,
The polyester resin (A) has an ester bond concentration of 7 mmol/g or less, a total concentration of amide groups, imide groups, urethane groups, and urea groups of 2 mmol/g or less, an acid value of 3 mgKOH/g or more, and a glass transition. An adhesive composition characterized by having a temperature (Tg) of -5°C or higher. 2. The adhesive composition according to claim 1, wherein a bisphenol skeleton-containing monomer is contained as the polyhydric alcohol, and the content of the bisphenol skeleton-containing monomer is 10 mol % or more based on the total polyhydric alcohol. 3. The adhesive composition according to claim 1, wherein the polyester-based resin (A) has a carboxyl group in its side chain. The adhesive composition according to any one of claims 1 to 3, wherein the content of the polyester resin (A) in the polyester resin is more than 50% by weight. 5. The adhesive composition according to any one of claims 1 to 4, further comprising a polyepoxy compound (B). An adhesive obtained by curing the adhesive composition according to any one of claims 1 to 5. 7. The adhesive according to claim 6, which is used for bonding electronic material members. 8. The adhesive according to claim 7, wherein the electronic material member is at least one selected from flexible copper-clad laminates, flexible printed boards, coverlays and bonding sheets.