JP7388485B2 - Adhesive compositions and adhesives - Google Patents

Description

The present invention relates to an adhesive composition containing a polyester resin and an adhesive obtained by curing this adhesive composition. Furthermore, the present invention relates to an adhesive composition having excellent long-term durability under a moist heat environment, and an adhesive obtained by curing this adhesive composition.

Traditionally, polyester resins have excellent heat resistance, chemical resistance, durability, and mechanical strength, so they have been used in a wide range of applications such as films, PET bottles, fibers, toners, electrical parts, adhesives, and adhesives. ing. In addition, polyester resin has high polarity due to its polymer structure, so it exhibits excellent adhesion to polar polymers such as polyester, polyvinyl chloride, polyimide, and epoxy resin, and to metal materials such as copper and aluminum. It has been known. Taking advantage of this property, its use as an adhesive for producing laminates of metal and plastic, such as flexible copper-clad laminates and flexible printed circuit boards, is being considered.

For example, Patent Document 1 discloses that a thermosetting adhesive sheet having excellent dimensional stability during curing and excellent adhesion, heat resistance, flexibility, electrical insulation, low dielectric constant, and low dielectric loss tangent after curing is obtained. For the purpose of
A thermosetting composition containing a resin (for example, a polyester resin), an organometallic compound, and a trifunctional or more functional epoxy group-containing compound in an amount of ol/g or more and 9 mmol/g or less has been proposed.

Furthermore, Patent Document 2 discloses that aromatic dicarbonate is Adhesive compositions containing an acid component and a polyester resin consisting of a dimer diol, a specific glycol, a glycol or oxyacid with a specific structure, and an alkylene glycol having 2 to 10 carbon atoms have been proposed.

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

However, in recent years, physical properties required for adhesive layers such as flexible copper-clad laminates and flexible printed circuit boards include curability, heat resistance, and initial adhesion, as well as tack-free properties from the point of view of rework. From this point of view, there is a strong demand for low moisture absorption and long-term durability in humid and heat environments.

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. There were problems such as a decrease in the transition temperature, resulting in poor initial adhesion and tack formation, making rework difficult. Further, Patent Document 1 does not consider long-term durability under a moist heat 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 has relatively excellent moist heat resistance and low moisture absorption, the glass transition temperature is too low, making it difficult to use polyimide or other materials. There were problems such as insufficient adhesion to copper and tackiness. Additionally, because it contains ether bond-containing glycols such as polypropylene glycol, and because it does not have an acid value that acts as a reaction point with epoxy resin, there is also the problem of poor heat resistance, and further improvements are required. .

Therefore, in the present invention, against this background, low moisture absorption, tack-free property before curing,
The object of the present invention is to provide an adhesive composition that has excellent initial adhesion after curing and long-term durability under a moist heat environment, and an adhesive obtained by curing this adhesive composition.

However, as a result of extensive research in view of the above circumstances, the present inventors have developed an adhesive composition containing a polyester resin, which has a low glass transition temperature (Tg) while lowering the ester bond concentration of the polyester resin. By increasing the acid value and adding an acid value above a specified value, we have created an adhesive composition with low moisture absorption, tack-free properties before curing, initial adhesion after curing, and excellent long-term durability in humid heat environments. They discovered that it can be used as a material, 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. 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 adhesive composition described above.

As mentioned in connection with Patent Document 1, a large amount of polyhydric carboxylic acid or polyhydric alcohol having a long-chain alkyl group is usually used in order to reduce water absorption, but on the other hand, initial adhesion and tack-free properties are , and long-term durability in a moist heat environment is reduced.
The present inventor has realized that by adjusting the composition of the monomers constituting the polyester resin,
By optimizing the ester bond concentration, acid value, and glass transition temperature (Tg), we have achieved low moisture absorption, tack-free properties before curing, initial adhesion after curing, and long-term durability in humid heat environments. The present invention was completed based on the discovery that it has excellent properties.

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 heat environment. It has excellent effects, especially as an adhesive for producing laminates of metal and plastic, such as flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards, coverlays, bonding sheets, etc. Effective for adhesives used in

Hereinafter, the structure of the present invention will be explained in detail, but these are examples of desirable embodiments.
In the present invention, the term "class" added after a compound name is a concept that includes not only the compound but also derivatives of the compound. For example, the term "carboxylic acids" includes not only carboxylic acids but also carboxylic acid derivatives such as carboxylic acid salts, carboxylic acid anhydrides, carboxylic acid halides, and carboxylic esters.

The adhesive composition of the present invention contains at least a polyester resin (A) containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin (A) will be explained.

<Polyester resin (A)>
The polyester resin (A) contains a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol in its molecule, and preferably the polyhydric carboxylic acid and the polyhydric alcohol are bonded together by an ester bond. This can be obtained by doing so.

[Polycarboxylic acids]
Examples of the polycarboxylic acids in the polycarboxylic acids include aromatic polycarboxylic acids described below; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,
Alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid and its acid anhydride; Aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, etc. . One type or two or more types of polyhydric carboxylic acids can be used.

It is preferable to contain aromatic polycarboxylic acids as the polycarboxylic acids. Examples of aromatic polycarboxylic acids include aromatic dicarboxylic acids and derivatives thereof (aromatic dicarboxylic acids) such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, biphenyldicarboxylic acid, and diphenic acid. Also, p-hydroxybenzoic acid, 6-
Examples include aromatic oxycarboxylic acids such as hydroxy-2-naphthoic acid. 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-mentioned aromatic polycarboxylic acids. Examples of aromatic carboxylic acids in trifunctional or higher-functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), and 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 dianhydride, and the like.
Among these, aromatic dicarboxylic acids are preferred, particularly terephthalic acid and isophthalic acid, and still more preferred is isophthalic acid.

The content of aromatic polycarboxylic acids based on the entire polycarboxylic acids is preferably 25 mol% or more, more preferably 40 mol% or more, particularly preferably 70 mol% or more,
More preferably, it is 90 mol% or more. Aromatic polycarboxylic acids may account for 100 mol%. If the content of aromatic carboxylic acids is too low, long-term durability in a humid heat environment tends to be insufficient.

The content (molar ratio) of aromatic polycarboxylic acids to the entire polycarboxylic acids is determined 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 dicarboxylic acid salts having a sulfonic acid group such as metal salts and ammonium salts thereof, from the viewpoint of hygroscopicity of the polyester resin (A), the content of which is 10 mol% or less based on the total polyhydric carboxylic acids. It is preferably at most 5 mol%, particularly preferably at most 3 mol%, even more preferably at most 1 mol%, and most preferably at most 0 mol%.

[Polyhydric alcohols]
Examples of the 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 bisphenol skeleton-containing monomers include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, and bisphenol BP.
, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4,
4'-dihydroxybenzophenone, bisphenol fluorene and their hydrogenated products, and glycols such as ethylene oxide adducts and propylene oxide adducts obtained by adding one to several moles of ethylene oxide or propylene oxide to the hydroxyl group of bisphenols. etc. Among these, those containing a bisphenol A skeleton are preferred, and from the viewpoint of reactivity, ethylene oxide adducts are preferred, particularly those containing 2 to 3 moles of ethylene oxide from the viewpoint of heat resistance, low hygroscopicity, and long-term durability in a humid heat environment. Preferably.

The content of the bisphenol skeleton-containing monomer based on the entire 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 small, low hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.
Note that the upper limit of the content of the bisphenol skeleton-containing monomer relative 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, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-
Examples include ethyl-2-butylpropanediol, dimethylolheptane, and 2,2,4-trimethyl-1,3-pentanediol.

Examples of the alicyclic polyhydric alcohol include 1,4-cyclohexanediol, 1,4-
Examples include cyclohexanedimethanol, tricyclodecanediol, tricyclodecane dimethanol, spiroglycol and the like.

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

In addition, ether bond-containing glycols other than bisphenol skeleton-containing monomers such as diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are heat resistant, have low hygroscopicity, and are heat resistant. 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, and even more preferably 8% by weight. % or less, most preferably 5% by weight or less.

[General raw material compounds constituting polyester resin (A)]
The compound constituting the polyester resin (A) may contain dimer acids as polyhydric carboxylic acids, and may contain dimer diols as polyhydric alcohols, regardless of whether it contains dimer acids. May contain.
In the present invention, the compound constituting the polyester resin (A) 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 dimer diols which are reduced forms thereof, and hydrogenated products thereof.
Among these, 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 aromatic acids in the polyhydric carboxylic acid components, and hydrogenated dimer diols are particularly preferred. They are diols.

The total content (α + β) (mol%) of the content (α) of dimer acids based on the total polyhydric carboxylic acids and the content (β) of dimer diols based on the total polyhydric alcohols is 5 mol% or more. It is preferably at least 10 mol%, particularly preferably at least 15 mol%, even more preferably at least 20 mol%. Also, 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, low hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.
If β) (mol %) is too large, the tack-free property before curing and the initial adhesiveness after curing tend to be insufficient.

Furthermore, 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, even more preferably 0.9 or more, and most preferably 1.

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

The total content (α + β) (weight%) of the content (α) of dimer acids and the content (β) of dimer diols 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, even more preferably 30% by weight or more, and the total content (α + β) (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 even more preferably 50% by weight or less.

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

Furthermore, oxycarboxylic acid compounds having a hydroxyl group and a carboxy group in their molecular structure can also be used as raw material compounds for the polyester resin (A). Examples of such oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, and p-hydroxybenzoic acid.
Hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-
Examples include naphthoic acid and 4,4-bis(p-hydroxyphenyl)valeric acid.

In addition to the polycarboxylic anhydride described below, the polyester resin (A) used in the present invention contains trifunctional or higher-functional polycarboxylic acids, and 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 concentration of end groups (reaction points) in the resin, making it possible to obtain a strong coating film with a high crosslinking density.

Examples of trifunctional or higher polycarboxylic acids in this case include 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 Examples include compounds such as anhydride, 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride, and the like. In addition, as trifunctional or more functional polyhydric alcohols, for example,
Examples include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.
Each of the trifunctional or more functional polyhydric carboxylic acids and the trifunctional or more functional polyhydric alcohol can be used alone or in combination of two or more.

When at least one selected from the group consisting of trifunctional or higher functional polycarboxylic acids and trifunctional or higher functional polyhydric alcohols is used separately from the polyvalent carboxylic acid anhydride described below, the entire polyvalent carboxylic acids The content of trifunctional or more polyhydric carboxylic acids relative to the whole polyhydric alcohol, or the content of trifunctional or more polyhydric alcohol relative to the whole polyhydric alcohol, is preferably 0.1 to 0.
5 mol%, more preferably 0.1 to 3 mol%. If the content of both or either one is too large, the mechanical properties such as elongation at break of the coating formed by applying the adhesive tend to decrease, and there is also a tendency to cause gelation during polymerization. .

The polyester resin (A) in the present invention preferably has a carboxyl group in the side chain in terms of curing speed and heat resistance after curing. Such polyester resin (A)
By copolymerizing a copolymerization component containing a polycarboxylic anhydride having a carboxylic anhydride structure (hereinafter sometimes simply referred to as "polycarboxylic anhydride") as a polycarboxylic acid, can get.

The polyhydric carboxylic acid anhydride preferably has at least two carboxylic acid anhydride structures for the purpose of introducing a carboxylic acid group into the side chain, for example, 1,2,4,5-
Benzenetetracarboxylic dianhydride (pyromellitic dianhydride), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4-oxydiphthalic dianhydride, 2,3,
6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, ethylene glycol bistrimelitate dianhydride, 3,3',4,4'-
Aromatic polycarboxylic acids such as diphenyltetracarboxylic dianhydride, 2,2',3,3'-diphenylsulfonetetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride Anhydrous;
1,2,3,4-cyclobutanetetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride,
Alicyclic polycarboxylic acid anhydrides such as 5-(2,5-dioxotetrahydrofuryl)-3-cyclohexene-1,2-dicarboxylic anhydride and cyclopentanetetracarboxylic dianhydride;
Aliphatic polyhydric carboxylic acid anhydrides such as ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, and 1,2,3,4-pentanetetracarboxylic dianhydride;
etc. One type selected from these can be used alone or two or more types can be used in combination.

Among these polyhydric 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 heat environment are important. , preferably aromatic polycarboxylic acid anhydrides, 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, particularly preferably 1,2 , 4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride).

The content of polycarboxylic anhydride in the polycarboxylic acids is preferably 0.5 to 20 mol%, more preferably 1 to 15 mol%, particularly preferably 2 to 20 mol%, based on the entire polycarboxylic acids. ~10 mol%, more preferably 3~8 mol%. If the content is too small, heat resistance tends to be insufficient, and if the content is too large, the polyester resin (A
) tend to gel during the manufacturing process, have low moisture absorption, and have insufficient long-term durability in humid heat environments.

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

Examples of a method for introducing an acid value into a polyester resin include a method of introducing a carboxylic acid into the resin by acid addition after an esterification reaction or after vacuum polycondensation. When a monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compound is used for acid addition, a decrease in molecular weight may occur 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 Anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2'-
Examples include compounds such as bis[(dicarboxyphenoxy)phenyl]propane dianhydride.

When the total polycarboxylic acids constituting the polyester resin (A) is 100 mol%,
If 15 mol% or more of acid is added, gelation may occur, and depolymerization of the polyester may occur, resulting in a decrease in the molecular weight of the resin. Examples of the acid addition method include a method in which the acid is added directly in a bulk state, and a method in which the polyester is dissolved and added. The reaction in the bulk state is fast, but gelation may occur if a large amount is added, and the reaction takes place at high temperatures, so care must be taken to prevent oxidation by blocking oxygen gas. On the other hand, addition in a solution state allows a large amount of carboxy groups to be stably introduced, although the reaction is slow.

In addition, when obtaining a polyester resin having a carboxyl group in the side chain, polyvalent A method of reacting a carboxylic acid anhydride is preferred from the viewpoint of productivity.

[Ester bond concentration of polyester resin (A)]
The ester bond concentration of the polyester resin (A) 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,
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 heat environment will become insufficient. Moreover, if the ester bond concentration is too low, the initial adhesiveness will be insufficient.

The definition and measurement method of ester bond concentration are as follows.
The ester bond concentration (mmol/g) refers to the number of moles of ester bonds in 1 g of polyester resin, and is determined, for example, by a calculated value from the amount of the ester bond. This calculation method is
It is the value obtained by dividing the smaller number of moles of each of the charged amounts of polyhydric carboxylic acids and polyhydric alcohols by the total weight of the resin, and an example of the calculation formula is shown below.
In addition, when the respective amounts of polyhydric carboxylic acids and polyhydric alcohols are the same molar amount, either of the following calculation formulas may be used.
In addition, when using a monomer having both a carboxyl group and a hydroxyl group, or when producing polyester from caprolactone or the like, the calculation method must 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: Amount of polyvalent carboxylic acids (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 polyhydric alcohols are less 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 (g)
b: Molecular weight of polyhydric alcohol n: Number of hydroxyl groups per molecule of polyhydric alcohol Z: Finished weight (g)

The above-mentioned 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 ester bonds and reactive functional groups is preferably low in terms 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, and a carbonate group.

The total concentration of amide groups, imide groups, urethane groups, and urea groups is 3 mmol/g.
It is preferably at most 2 mmol/g, more preferably at most 1 mmol/g, even more preferably at most 0.5 mmol/g, and most preferably at most 0.2 mmol/g. .
Examples of the ether group include an alkyl ether group and a phenyl ether group,
From the viewpoint of low hygroscopicity and long-term durability under a moist heat environment, it is particularly preferable to reduce the concentration of alkyl ether groups.
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. Furthermore, 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, even 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, even more preferably 0.5 mmol/g or less, and most preferably is 0.2 mmol/g or less.

[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, even 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), there will be insufficient crosslinking points with the polyepoxy compound (B) and the degree of crosslinking will be low, resulting in poor heat resistance. It will be enough. In addition, if the acid value is too high, hygroscopicity and long-term durability in a moist heat environment will decrease, and a large amount of polyepoxy compound (B) will be required during curing, so it has been often required in recent years. The resulting dielectric properties tend to be inferior.

The definition and measurement method of acid value are as follows.
The acid value (mgKOH/g) is determined by dissolving 1 g of polyester resin in 30 g of a mixed solvent of toluene/methanol (e.g., toluene/methanol = 7/3 by volume), and calculating the JIS K00
It can be determined by neutralization titration based on 70.
In the present invention, the acid value of the polyester resin (A) is determined by 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.
, more preferably 7 to 40°C, most preferably 10 to 30°C.
If the glass transition temperature (Tg) is too low, initial adhesion and tack-free properties will be insufficient.
Furthermore, if the glass transition temperature (Tg) is too high, initial adhesion and flexibility tend to be insufficient.

The method for measuring glass transition temperature (Tg) is as follows.
Glass transition temperature (Tg) can be determined by measuring using a differential scanning calorimeter. Note that the measurement conditions were 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 5000
-150,000 is preferable, more preferably 10,000 - 100,000, particularly preferably 15,000 - 70,000, even more preferably 25,000 - 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 may become insufficient, and flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards may be insufficient. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and ooze out during press processing. In addition, the peak top molecular weight (M
If p) is too high, the initial adhesion may be insufficient or the solution viscosity during coating may be too high, making it difficult to obtain a uniform coating.

The weight average molecular weight (Mw) of the polyester resin (A) used in the present invention is 5000 to 3
00000 is preferable, more preferably 10000 to 200000, particularly preferably 20
000 to 150,000, 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 may be insufficient, and flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards may be insufficient. There is a tendency for problems such as the polyester resin in the adhesive layer to flow and ooze out during press processing. Furthermore, if the weight average molecular weight (Mw) is too high, the initial adhesion may be insufficient, or the solution viscosity during coating may be too high, making it difficult to obtain a uniform coating film.

The method for measuring the peak top molecular weight (Mp) and weight average molecular weight (Mw) is as follows.
The peak top molecular weight (Mp) and weight average molecular weight (Mw) were measured using a column (TSKgel Supe) using high performance liquid chromatography (Tosoh Corporation, "HLC-8320GPC").
rMultipore HZ-M (exclusion limit molecular weight: 2×10 ⁶ , number of theoretical plates: 16000
It can be measured using two columns in series, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm), and calculated by converting to standard polystyrene molecular weight.

[Water absorption rate (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, even more preferably 0.6% by weight or less. be.
If the water absorption rate is too high, wet heat durability and insulation reliability tend to decrease, and dielectric properties tend to deteriorate. Note that poor dielectric properties mean that the values of relative permittivity and dielectric loss tangent do not become small;
Alternatively, it means that the value becomes larger.

The method for measuring water absorption rate is as follows.
Apply the polyester resin solution (before blending the polyepoxy compound (B)) onto the release film using an applicator and dry at 120°C for 10 minutes until the dry film thickness of the polyester resin layer is 6.
A 5 μm sheet was produced. This sheet was cut into a size of 7.5 cm x 11 cm, the polyester resin layer side 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 resin layer with 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 moisture is wiped off, and the 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.
(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 it from 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 based on the entire polyester resin. It is at least 85% by weight, particularly preferably at least 85% by weight. If this content is too small, low hygroscopicity and long-term durability in a moist heat environment tend to be insufficient.

<Polyepoxy compound (B)>
It is preferable that the adhesive composition of the present invention further contains a polyepoxy compound (B). By reacting and curing the epoxy group in the polyepoxy compound (B) and the carboxyl group in the polyester resin (A), an adhesive layer with excellent heat resistance and adhesive strength as well as solder heat resistance is created. Obtainable.

Examples of the polyepoxy compound (B) used in the present invention include bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A
Difunctional glycidyl ether types such as diglycidyl ether; polyfunctional glycidyl ether types such as phenol novolac glycidyl ether and cresol novolak glycidyl ether; glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; triglycidyl isocyanurate, Examples include alicyclic or aliphatic epoxides such as 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. One type or two or more types of polyepoxy compounds (B) 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 can be formed by heating at a relatively low temperature. It is possible to B-stage the coating film of an object (semi-cured state), and it tends to be possible to suppress the fluidity of the B-stage film and improve workability in bonding operations. Further, it is preferable because it can be expected to have the effect of suppressing foaming of the B-stage film.

Examples of nitrogen atom-containing polyepoxy compounds include glycidyl amines such as tetraglycidyldiaminodiphenylmethane, triglycidyl para-aminophenol, tetraglycidyl bisaminomethylcyclohexanone, and N,N,N',N'-tetraglycidyl-m-xylene diamine. Examples include systems.

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 a nitrogen atom-containing polyepoxy compound The content of is 30% based on the entire polyepoxy compound (B).
It is preferably at most 25% by weight, more preferably at most 25% by weight, particularly preferably at most 20% by weight.
% by weight or less.
In addition, the content of the nitrogen atom-containing polyepoxy compound is the same as the content of the polyester resin (A
) It is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, particularly preferably 2 parts by weight or less, per 100 parts by weight.
If the content of such a nitrogen atom-containing polyepoxy compound is too high, the rigidity tends to become excessively high and the adhesiveness tends to decrease, and the crosslinking reaction tends to proceed during storage of the adhesive sheet, reducing the sheet life. There is a tendency to

The equivalent weight 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 amount is too large, the initial adhesion and low moisture absorption properties tend to be insufficient, and the dielectric properties tend to be poor. On the other hand, if it is too small, long-term durability and soldering heat resistance in a moist heat environment tend to be insufficient.

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

<Adhesive composition>
The adhesive composition of the present invention contains at least a polyester resin (A), preferably further contains a polyepoxy compound (B), and has low hygroscopicity, tack-free property before curing, and initial It has excellent adhesive properties and long-term durability under moist heat environments.

In the adhesive composition of the present invention, a filler, a flame retardant, etc. may be blended, and in that case, the content of the polyester resin (A) in the adhesive composition may be determined by blending the filler, flame retardant, etc. In consideration of this, it is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, even more preferably 60% by weight, based on the total solid content.
~85% by weight.

Further, when the adhesive composition of the present invention contains a polyepoxy compound (B), the content of the polyepoxy compound (B) is preferably 1 part by weight based on 100 parts by weight of the polyester resin (A). The amount is 30 parts by weight, more preferably 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight, even more preferably 4 to 10 parts by weight. If the content of the polyepoxy compound (B) is too low, heat resistance and long-term durability in a moist heat environment tend to be insufficient, and if it is too high, initial adhesion and low moisture absorption may become insufficient. , they tend to have poor dielectric properties.

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 ease of handling and workability in molding the adhesive composition, and there is no particular restriction on the amount used.

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- Examples include amides such as dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; and aromatics such as toluene and xylene. The above-mentioned solvents may be used alone or in a mixture 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 ingredients include, for example, inorganic fillers, coupling agents such as silane coupling agents, ultraviolet inhibitors, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, low-elasticity agents, and diluents. agent, antifoaming agent, ion trapping agent, leveling agent, catalyst, etc.
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, particularly preferably 0.1% by weight or less.
~50% by weight, more preferably 0.2~40% by weight.

<Adhesive>
The adhesive of the present invention is obtained by curing the adhesive composition described above, and exhibits the effects of excellent initial adhesiveness, low moisture absorption, and long-term durability in a moist heat environment.
"Curing" in the present invention means intentionally curing the adhesive composition by heat and/or light, and the degree of curing can be controlled depending on desired physical properties and intended use. 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, and still more preferably 75% or more. If the gel fraction is too low, heat resistance and long-term durability in a moist heat environment tend to be insufficient.
Note that the above-mentioned gel fraction means the weight percentage of the undissolved adhesive component relative to the weight of the adhesive before immersion when the adhesive is immersed in methyl ethyl ketone at 23° C. for 24 hours.

The curing method for curing or semi-curing the adhesive composition of the present invention to produce an adhesive varies depending on the components and amount of the adhesive composition, but is usually at 80 to 200°C. de1
Heating conditions include 0 minutes to 10 hours.

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, and 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-
Tertiary amines such as diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; Examples include compounds made into amine salts with octylic acid, quaternized tetraphenylborate salts, etc.; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diallyliodonium hexafluoroantimonate; triphenylphosphine, and the like. Among these, 1,8-diazabicyclo(5,4,0)-undecene-7 and 1,5-diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(
Tertiary amines such as 5,4,0)-undecene-7; and compounds in which these tertiary amines are made into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc. are thermosetting and It is preferable in terms of heat resistance, adhesion to metals, and storage stability after blending.
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 resin (A) and the polyepoxy compound (B) will further increase, and strong adhesive performance can be obtained.

[Application]
The adhesive of the present invention has excellent initial adhesion, low moisture absorption, and long-term durability in a moist heat environment.
Effective for adhering base materials made of various materials such as resins and metals, especially adhesives for producing laminates of metal layers and plastic layers, such as adhesives used for bonding electronic material parts. suitable for
Examples of the "electronic material member" in the present invention include flexible printed circuit boards, coverlays, bonding sheets, and the like.
Examples of products manufactured by bonding electronic material members include flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards. A flexible laminate is, for example, a laminate in which "a flexible flexible substrate/adhesive layer/a conductive metal layer made of copper, aluminum, an alloy thereof, etc." are laminated in sequence, and the adhesive layer constitutes the flexible laminate. The adhesive of the present invention can be used as the adhesive. In addition, the flexible laminate may further include other insulating layers, other adhesive layers, and other conductive metal layers in addition to the various layers described above.

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 unless it exceeds the gist thereof. In addition, "part" and "%" in the examples mean a weight basis.

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

<Manufacture of polyester resin>
The composition (molar ratio) listed in Table 1 below is the finished composition ratio (resin composition ratio),
This 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)]
In a reaction vessel equipped with a thermometer, stirrer, rectification column, and nitrogen inlet tube, 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as a polyhydric carboxylic acid and ethylene of bisphenol A as a polyhydric alcohol were added. Approximately 2 moles of oxide 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), dimer diol "Pripol 203"
3'' (P2033) (manufactured by Croda), 254.4 parts (0.4801 mol) and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the temperature was raised over 120 minutes until the internal temperature reached 270°C. The esterification reaction was carried out at ℃ for 3 hours.
Next, the internal temperature was lowered to 200°C, and 15.0 parts (0
．． 0,688 mol) was added and an addition reaction was carried out at 200°C for 2 hours to obtain a polyester resin (A-1) having the resin composition and physical properties shown in Table 1.

[Production Example 2, Comparative Production Examples 1 to 3: Polyester resin (A-2, A'-1, A'-2, A'
-3) Manufacturing]
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 various 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" : Approximately 2 moles of ethylene oxide adduct of bisphenol A "Newpol BPE-20" (manufactured by Sanyo Chemical Industries, Ltd.)
"P2033": Dimerdiol "Pripol 2033" (manufactured by Croda)

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

<Manufacture of adhesive composition>
An adhesive composition was produced as described below using the polyester resin and polyepoxy compound obtained above.

(Example 1)
The polyester resin (A-1) obtained above was added to methyl ethyl ketone to a solid content concentration of 60.
%, and for this polyester resin (A-1) solution (100 parts as solid content),
An adhesive composition was obtained by adding 10 parts of polyepoxy compound (B-1) (solid content), diluting with methyl ethyl ketone to a solid content of 50%, stirring and mixing.

(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 composition was evaluated as follows. The results are shown in Table 2.

<Preparation of laminate>
The adhesive composition prepared above was applied to a 50 μm thick polyimide film “Kapton 200H”.
'' (manufactured by DuPont-Toray) with an applicator and dried at 120° C. for 5 minutes to form an adhesive layer with a dry thickness of 25 μm. Next, (1) rolled copper foil with a thickness of 30 μm, or (2)
A polyimide film "Kapton 200H" with a thickness of 50 μm was laminated with the adhesive layer surface of each of the above polyimide films with an adhesive layer (lamination conditions: 170° C., 0.2 MPa, feeding speed 1.5 m/min), and then heated in an oven at 160° C. for 4 hours. Each laminate was obtained by heat treatment and curing for a period of time.
For convenience, a laminate laminated with rolled copper foil (polyimide film/adhesive layer/rolled copper foil)
is expressed as PI/Cu, and a laminate laminated with a polyimide film (polyimide film/adhesive layer/polyimide film) is expressed as PI/PI.

<Evaluation>
[Initial adhesive strength]
A test piece was prepared by cutting the laminate obtained above into a 1 cm wide piece. The test piece was fixed to a 2 mm thick glass plate 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). , peeling angle: 1
80°). The evaluation criteria were as follows.
◎: 8N/cm or more ○: 6N/cm or more, less than 8N/cm △: 4N/cm or more, less than 6N/cm ×: Less than 4N/cm

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

[Tack-free property]
The adhesive layer surface of the adhesive layer-attached polyimide film before curing obtained above was touched lightly with a finger and evaluated based on the following evaluation criteria.
◎: Almost no stickiness felt.
○: Stickiness is not felt very much.
△: Slightly sticky.
×: Sticks to fingers.

[Gel fraction]
The polyimide film with an adhesive layer obtained above was cured by heat treatment at 160° C. for 4 hours, and then cut into a size of 4 cm×4 cm. Wrap this in a 200 mesh SUS wire mesh,
It was 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 of Production Examples 1 and 2 that meet the requirements of the present invention (
A-1) and (A-2) have excellent low moisture absorption, and the adhesive compositions of Examples 1 to 3 obtained using them have tack-free properties before curing, initial adhesion after curing, Furthermore, it has excellent long-term durability under a humid heat 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 have poor long-term durability in a moist heat environment. It was something. Polyester resin of Comparative Production Example 2 (A'-2), which also has a high ester bond concentration
The adhesive compositions of Comparative Examples 3 and 4 obtained using the same method also had poor long-term durability in a moist heat environment.
In addition, the adhesive composition of Comparative Example 5 obtained using the polyester resin (A'-3) of Comparative Production Example 3, which has a low glass transition temperature, has tack-free properties before curing and initial adhesion after curing. It 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 heat environment. It is particularly effective as an adhesive for producing metal-plastic laminates, for example, for flexible copper-clad laminates, flexible printed circuit boards, and other flexible laminates. be.

Claims (8)

An adhesive composition containing a polyester resin (A) containing a structural unit derived from polyhydric carboxylic acids and a structural unit derived from polyhydric alcohols,
Aromatic polycarboxylic acids are contained as the polycarboxylic acids, and the content of the aromatic polycarboxylic acids based on the entire polycarboxylic acids is 25 mol% or more,
The polyester resin (A) has an ester bond concentration of 7 mmol/g or less, an acid value of 3 mgKOH/g or more, a glass transition temperature (Tg) of -5°C or more, and an alkyl ether group concentration of 3 mmol/g or less. , the total concentration of amide groups, imide groups, urethane groups, and urea groups is 2 mmol/g or less ,
An adhesive composition characterized in that the content of the polyester resin (A) in the polyester resin is more than 50% by weight. Contains at least one selected from the group consisting of dimer acids as polyhydric carboxylic acids and dimer diols as polyhydric alcohol, and the content (α) of dimer acids relative to the entire polyhydric carboxylic acids and the entire polyhydric alcohol. 2. The adhesive composition according to claim 1, wherein the total content (α+β) of the content (β) of dimer diols is 5 mol% or more. 3. The adhesive composition according to claim 1, wherein the adhesive composition contains a bisphenol skeleton-containing monomer as the polyhydric alcohol, and the content of the bisphenol skeleton-containing monomer based on the entire polyhydric alcohol is 10 mol% or more. The adhesive composition according to any one of claims 1 to 3, wherein the polyester resin (A) has a carboxyl group in a side chain. The adhesive composition according to any one of claims 1 to 4, further comprising a polyepoxy compound (B). An adhesive characterized in that the adhesive composition according to any one of claims 1 to 5 is cured. 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 a flexible copper-clad laminate, a flexible printed circuit board, a coverlay, and a bonding sheet.