JP7223300B2 - Polyester resin, adhesive composition and adhesive - Google Patents

Description

The present invention relates to a polyester-based resin, an adhesive composition containing the polyester-based resin, and an adhesive obtained by curing this adhesive composition. Also, the initial adhesive property after curing, further polyester resin forming an adhesive composition excellent in long-term durability in a hot and humid environment, further adhesive composition containing a polyester resin and its adhesion The present invention relates to adhesives in which the agent composition is cured.

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 having excellent adhesion to various plastics, metals, and glass epoxy, resistance to moist heat, and adhesion at high temperature and high humidity, a thermoplastic resin (polyester resin) is disclosed. , an inorganic filler, a solvent, and an epoxy resin under predetermined conditions.

Japanese Patent Application Laid-Open No. 2017-031301 JP 2015-187271 A

However, in recent years, in the field of electronic materials such as flexible copper-clad laminates and flexible printed circuit boards, the physical properties required for the adhesive layers used there are, in addition to adhesiveness, further lower dielectric properties as the frequency of transmission signals increases. Low dielectric properties, especially low dielectric loss tangent, such as low dielectric constant and low dielectric loss tangent, are becoming highly sought after.

In the technique 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, thereby increasing the glass transition temperature. As a result, the initial adhesion deteriorates, and the wet heat durability becomes insufficient. In addition, the concentration of ester bonds has been lowered in order to achieve a low dielectric constant, a low dielectric loss tangent, and a low water absorption rate. rice field.

In addition, the technique disclosed in Patent Document 2 attempts to improve adhesiveness, but does not consider dielectric properties, and is not sufficient to meet the recent demand for low dielectric properties. .

Therefore, in the present invention, under such a background, an adhesive composition having a low dielectric constant and a low dielectric loss tangent, and having excellent initial adhesiveness after curing and long-term durability in a moist and hot environment is formed. It is an object of the present invention to provide a polyester-based resin, an adhesive composition containing the polyester-based resin, and an adhesive obtained by curing the adhesive composition.

However, as a result of extensive research in view of such circumstances, the inventors of the present invention have found that the following polyester resins (1) to (4) meet the objects of the present invention, and have completed the present invention.
(1) A polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, having a glass transition temperature (Tg) of −5° C. or higher, a temperature of 23° C., and a relative humidity of 50 A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz in a %RH environment.
(2) A polyester resin containing a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, having an acid value of 3 mgKOH/g or more, at a temperature of 23°C and a relative humidity of 50% RH. A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz.
(3) A polyester resin containing structural units derived from polycarboxylic acids and structural units derived from polyhydric alcohols, having a glass transition temperature (Tg) of −5° C. or higher and an acid value of 3 mgKOH/g or higher. A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz under an environment of a temperature of 23° C. and a relative humidity of 50% RH.
(4) A polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, the dielectric loss tangent (α) at 10 GHz in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH A polyester resin of 0.0030 or less.

That is, the present invention has the following aspects [1] to [15].
[1] A polyester resin containing structural units derived from polycarboxylic acids and structural units derived from polyhydric alcohols, having a glass transition temperature (Tg) of −5° C. or higher, a temperature of 23° C., and a relative humidity of 50 A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz in a %RH environment.
[2] A polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, having an acid value of 3 mgKOH/g or more, at a temperature of 23° C. and a relative humidity of 50% RH. A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz.
[3] A polyester resin containing structural units derived from polycarboxylic acids and structural units derived from polyhydric alcohols, having a glass transition temperature (Tg) of −5° C. or higher and an acid value of 3 mgKOH/g or higher. A polyester resin having a dielectric loss tangent (α) of 0.0050 or less at 10 GHz under an environment of a temperature of 23° C. and a relative humidity of 50% RH.
[4] A polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, the dielectric loss tangent (α) at 10 GHz in an environment with a temperature of 23 ° C. and a relative humidity of 50% RH A polyester resin of 0.0030 or less.
[5] The polyester resin according to any one of [1] to [4], wherein the polycarboxylic acids include aromatic polycarboxylic acids.
[6] The polyester resin according to any one of [1] to [5], wherein the polyvalent carboxylic acid contains a trivalent or higher polyvalent carboxylic acid having 0 or 1 acid anhydride group.
[7] The polyester resin according to any one of [1] to [6], wherein the polyhydric alcohol contains dimer diol.
[8] The polyester resin according to any one of [1] to [7], wherein at least one of polyhydric carboxylic acids and polyhydric alcohols contains a condensed polycyclic aromatic compound.
[9] The polyester resin according to any one of [1] to [8], which is amorphous.
[10] An adhesive composition comprising the polyester resin according to any one of [1] to [9].
[11] The adhesive composition of [10], which further contains a curing agent.
[12] The adhesive composition according to [10] or [11], wherein the content of the curing agent is 30 parts by weight or less per 100 parts by weight of the polyester resin.
[13] An adhesive obtained by curing the adhesive composition according to any one of [10] to [12].
[14] The adhesive according to [13], which is used for bonding electronic material members.
[15] The adhesive according to [14], wherein the electronic material member is at least one selected from flexible copper-clad laminates, coverlays and bonding sheets.

As described with reference to Patent Document 1 above, in order to reduce the water absorption, dielectric constant, and dielectric loss tangent, a large amount of polyhydric carboxylic acids and polyhydric alcohols having long-chain alkyl groups are usually used, and the ester bond concentration is low. However, on the other hand, the initial adhesiveness and the long-term durability in a moist and hot environment are degraded. Further, it is difficult to obtain even lower dielectric properties by lowering the ester bond concentration.
The present inventor prepared the composition of the monomers constituting the polyester resin and further optimized the acid value, glass transition temperature (Tg), etc., to achieve a lower dielectric constant and a lower dielectric constant than conventional polyester resins. The present inventors have completed the present invention based on the finding that the composition has excellent dielectric loss tangent, initial adhesiveness after curing, and long-term durability in a moist and hot environment.

The polyester-based resin of the present invention has a low dielectric constant and a low dielectric loss tangent, especially a low dielectric loss tangent, and forms an adhesive composition having excellent initial adhesiveness after curing and long-term durability in a moist and hot environment. In particular, such an adhesive composition is an adhesive for producing a laminate of metal and plastic, such as lamination of electronic material members, especially flexible copper-clad laminates, coverlays, and bonding sheets. It is effective as an adhesive used in the production of flexible printed wiring boards, etc.

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.
In the present invention, "x and/or y (x and y are arbitrary constituents or components)" means three combinations of x only, y only, and x and y.

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

<Polyester resin>
The polyester-based resin contains structural units derived from polycarboxylic acids and structural units derived from polyhydric alcohols in the molecule, and is preferably obtained by ester bonding polyhydric carboxylic acids and polyhydric alcohols. It is something that can be done.

[Polyvalent carboxylic acids]
Polyvalent carboxylic acids in polyvalent carboxylic acids include, for example, aromatic polyvalent carboxylic acids described later; trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups described later; 1,4-cyclohexanedicarboxylic acid Alicyclic polyvalent carboxylic acids such as acids, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their acid anhydrides; fats such as succinic acid, adipic acid, azelaic acid, sebacic acid and dodecanedioic acid Group polyhydric carboxylic acids can be mentioned. 1 type(s) or 2 or more types can be used for polyhydric carboxylic acid.

Polyvalent carboxylic acids preferably contain aromatic polyvalent carboxylic acids. Examples of aromatic polycarboxylic acids include monocyclic aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl isophthalate, and orthophthalic acid; biphenyldicarboxylic acid, naphthalenedicarboxylic acid, and naphthalenedicarboxylic acid; Polycyclic aromatic polycarboxylic acids such as dimethyl; among polycyclic aromatic polycarboxylic acids, naphthalenedicarboxylic acid, condensed polycyclic aromatic polycarboxylic acids such as dimethyl naphthalenedicarboxylate 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 an acid value to the polyester resin are also included in the above-mentioned aromatic polyvalent carboxylic acids. Tri- or higher functional aromatic polycarboxylic acids include, for example, trimellitic acid, trimesic acid, ethylene glycol bis (anhydrotrimellitate), glycerol tris (anhydrotrimellitate), trimellitic anhydride, pyro mellitic 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 and anhydrides.
Among these, from the viewpoint of dielectric properties, polycyclic aromatic polycarboxylic acids are preferred, and condensed polycyclic aromatic polycarboxylic acids are particularly preferred. Among condensed polycyclic aromatic polycarboxylic acids, Dimethyl naphthalenedicarboxylate is particularly preferred.
Among the monocyclic aromatic polycarboxylic acids, preferred are terephthalic acid, dimethyl terephthalate, isophthalic acid and dimethyl isophthalate.
Moreover, in order to lower the crystallinity and ensure the stability after dissolution in a solvent, it is preferable to use a plurality of types of polyvalent carboxylic acids.

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

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

Further, the content of the aromatic polycarboxylic acid relative to the entire polyester resin is preferably 15 to 70% by weight, more preferably 20 to 65% by weight, still more preferably 25 to 60% by weight, particularly preferably 30% by weight. ~55% by weight. If the content of the aromatic polycarboxylic acid is too low, the initial adhesiveness tends to be insufficient and the low dielectric loss tangent tends to be poor.

Polyvalent carboxylic acids preferably also contain trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups. The valence of the carboxy group in such polyvalent carboxylic acids is preferably 3-6 valence, more preferably 3-4 valence. Examples of such polyvalent carboxylic acids include those having 0 or 1 acid anhydride group among the above trifunctional or higher aromatic polyvalent carboxylic acids. Examples thereof include trimellitic anhydride, trimellitic acid, and trimesic acid. Among these, those having one acid anhydride group are preferred, and trimellitic anhydride is particularly preferred.
Examples of trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups other than aromatic polyvalent carboxylic acids include hydrogenated trimellitic anhydride.

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 sulfonate groups such as metal salts and ammonium salts thereof, from the viewpoint of the hygroscopicity of polyester resins, 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 dimer diols, bisphenol skeleton-containing monomers, aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, and aromatic polyhydric alcohols. One or two or more polyhydric alcohols can be used.

In the present invention, the compound constituting the polyester-based resin preferably contains dimer diols as polyhydric alcohols.
The dimer diols include, for example, dimer diols which are reductants of dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, etc. and the like. Among them, hydrogenated substances are preferable from the viewpoint of suppressing gelation during the production of polyester-based resins.

The dimer diol content relative to the total polyhydric alcohols is preferably 2 to 80 mol%, more preferably 5 to 70 mol%, particularly preferably 7 to 65 mol%, still more preferably 10 to 60 mol%. is. If the content of the dimer diols is too low, the hygroscopicity and dielectric properties tend to be poor, and if it is too high, the initial adhesiveness tends to be insufficient.

The content of dimer diols relative to the entire polyester resin is preferably 5 to 70 wt%, more preferably 10 to 60 wt%, still more preferably 12 to 55 wt%, and particularly preferably 15 to 50 wt%. %. If the content of the dimer diols is too low, the hygroscopicity and dielectric properties tend to be poor, and if it is too high, the initial adhesiveness tends to be insufficient.

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, Examples include bisphenylphenol fluorenes, 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 the hydroxyl group of bisphenols. . Among them, bisphenol fluorene and bisphenylphenol fluorene having a condensed polycyclic aromatic skeleton are preferable from the viewpoint of low dielectric properties, and ethylene oxide adducts are preferable from the viewpoint of reactivity, especially heat resistance, low moisture absorption, and moist heat. From the standpoint of long-term durability in the environment, adducts of 2 to 3 mol of ethylene oxide are preferred, and bisphenoxyethanolfluorene and bisphenylphenoxyethanolfluorene are most preferred.

From the viewpoint of low dielectric properties, it is preferable to use a small amount of bisphenol skeleton-containing monomers other than bisphenol fluorene, bisphenylphenol fluorene, and derivatives thereof. From the viewpoint of , the larger the amount, the better, and it is preferable to adjust the introduction amount according to the desired physical properties. On the other hand, it is preferable to introduce bisphenol fluorene, bisphenylphenol fluorene, and derivatives thereof into the polyester-based resin in terms of any of the above-mentioned physical properties such as solvent solubility, storage stability of the solution, low hygroscopicity, and low dielectric properties. The content of bisphenol fluorene and its derivatives with respect to the total polyhydric alcohols is preferably 2 to 50 mol%, more preferably 5 to 45 mol%, particularly preferably 10 to 40 mol%, still more preferably 15 to 35 mol %. If the content of bisphenol fluorene, bisphenylphenol fluorene and its derivatives is too high, the initial adhesiveness tends to be insufficient, and if it is too low, solvent solubility, storage stability, low hygroscopicity, and dielectric properties are insufficient. tend to be sufficient.

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, 1,10-decanediol, 2-ethyl-2-butylpropanediol, dimethylol Heptane, 2,2,4-trimethyl-1,3-pentanediol and the like can be mentioned. Among them, those having 5 or less carbon atoms are preferably used from the viewpoint of increasing the aromatic ring content and the alicyclic content, which will be described later.

Examples of alicyclic polyhydric alcohols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, spiroglycol and the like. Among these, polycyclic compounds are preferred from the viewpoint of low dielectric properties, and tricyclodecanedimethanol is more preferred.

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.

Among the above polyhydric alcohols, it is preferable to use a polyhydric alcohol having a side chain from the viewpoint of solvent solubility and solution stability. Examples of polyhydric alcohols having side chains include bisphenol A, bisphenol B, bisphenol E, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, bisphenol fluorene, bisphenylphenol fluorene, and their water Additives, ethylene oxide or propylene oxide adducts obtained by adding 1 to several moles of ethylene oxide or propylene oxide to hydroxyl groups of bisphenols, bisphenol skeleton-containing monomers having side chains such as propylene oxide adducts, 1,2-propylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, dimethylolheptane, 2,2,4-trimethyl- Aliphatic polyhydric alcohols having side chains such as 1,3-pentanediol, and alicyclic polyhydric alcohols having side chains such as tricyclodecanediol, tricyclodecanedimethanol and spiroglycol can be mentioned.
The content of the polyhydric alcohol having a side chain is preferably 10 mol % or more, more preferably 20 mol % or more, still more preferably 30 mol % or more, relative to the total polyhydric alcohols. In addition, an upper limit is 95 mol%. Moreover, it is 5% by weight or more, more preferably 10% by weight or more, and still more preferably 15% by weight or more with respect to the entire polyester resin. In addition, an upper limit is 50 weight%.
If the content of the polyhydric alcohol having a side chain is too small, the solvent solubility and the solution stability of the obtained polyester resin solution tend to decrease.

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 polyester-based resin]
At least one of the polyhydric carboxylic acids and polyhydric alcohols in the compound constituting the polyester resin preferably contains a condensed polycyclic aromatic compound from the viewpoint of low dielectric loss tangent. The condensed polycyclic aromatic compound is a condensed polycyclic aromatic compound of polyvalent carboxylic acids, for example, naphthalenedicarboxylic acid, dimethyl naphthalenedicarboxylate, anthracenedicarboxylic acid, and the like. From the viewpoint of , naphthalenedicarboxylic acids are preferable, and dimethyl naphthalenedicarboxylate is more preferable from the viewpoint of reactivity. These can be used alone or in combination of two or more. Examples of condensed polycyclic aromatic compounds of polyhydric alcohols include bisphenol fluorene, bisphenylphenol fluorene, and their derivatives such as ethylene oxide and propylene oxide adducts. is preferred, and bisphenoxyethanolfluorene and bisphenylphenoxyethanolfluorene are particularly preferred. These can be used alone or in combination of two or more.

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

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

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

In the present invention, it is also preferable to increase the alicyclic content from the viewpoint of low dielectric loss tangent.
As described above, aromatic polycarboxylic acids are preferable as polyhydric carboxylic acids from the viewpoint of long-term durability and low dielectric loss tangent in a moist and hot environment, so the introduction of the alicyclic skeleton is performed on the polyhydric alcohol side. is preferred.

Here, the definition and calculation method of the alicyclic content in the present invention are as follows.
The alicyclic content is the weight ratio of the atoms constituting the alicyclic ring in the polyester resin.

The alicyclic content can be calculated from the composition of the polyester resin. The calculation method is as follows.
Alicyclic content = A1 x (a11 x n11 + a12 x n12 + a13 x n13 ...) / (x1 - y1) + A2 x (a21 x n21 + a22 x n22 + a23 x n23 ...) / (x2 - y2) + A3 x (a31 x n31+a32×n32+a33×n33...)/(x3-y3)...
A: Content (% by weight) of structural units derived from each monomer in the polyester resin
a: Atomic weight of atoms constituting an alicyclic ring in each monomer (for example, 12 for carbon, 14 for nitrogen, etc.) When there are two or more types of atoms, a11, a12, a13, etc., for example, a11: carbon, a12: nitrogen, and a13: oxygen.)
n: number of atoms constituting the alicyclic ring in each monomer x: molecular weight of each monomer y: sum of formula weights of leaving groups in each monomer

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

In addition to the polycarboxylic acids used in the depolymerization reaction described later, the polyester-based resin used in the present invention includes tri- or higher-functional polycarboxylic acids and tri- or higher-functional polycarboxylic acids for the purpose of introducing a branched skeleton. At least one selected from the group consisting of hydric alcohols is preferably copolymerized. In particular, when a cured coating film is obtained by reacting with a curing agent, the introduction of a branched skeleton increases the terminal group concentration (reaction 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.

At least one selected from the group consisting of tri- or higher-functional polycarboxylic acids and tri- or higher-functional polyhydric alcohols for the purpose of introducing a branched skeleton, separately from the polycarboxylic acids used in the depolymerization reaction described later. When using, the content of tri- or more functional polycarboxylic acids with respect to the total polycarboxylic acids, or the content of tri- or more functional polyhydric alcohols with respect to the total polyhydric alcohols, each preferably 0.1 ~5 mol%, more preferably 0.3 to 3 mol%, still more preferably 0.5 to 2 mol%. If the content of both or either one is too large, the mechanical properties such as the elongation at break of the coating film formed by applying the adhesive tend to decrease, and the adhesive strength tends to decrease, and during polymerization. It also has a tendency to gel.

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

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 the carboxylic anhydride include succinic anhydride, maleic anhydride, orthophthalic anhydride, 2,5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, and pyromellitic dianhydride. , oxydiphthalic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-diphenyltetracarboxylic dianhydride, 3,3′,4, Compounds such as 4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride etc.

When 15 mol % or more of acid addition is performed, gelation may occur when the total amount of polyvalent carboxylic acids constituting the polyester resin is 100 mol %. Methods of acid addition include a method of direct addition in a bulk state and a method of dissolving and adding a polyester resin. 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.

In the present invention, another well-known method, for example, a polyhydric carboxylic acid and a polyhydric alcohol, optionally in the presence of a catalyst, is subjected to an esterification reaction to obtain a prepolymer. , polycondensation, and further depolymerization.

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

The temperature in the polycondensation is usually 220-280° C., and the reaction time is usually 20 minutes-4 hours. Moreover, it is preferable to perform polycondensation under reduced pressure.

For depolymerization, it is preferable to use trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups from the viewpoint of initial adhesiveness. Examples of trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride groups include compounds such as trimellitic acid, trimellitic anhydride, hydrogenated trimellitic anhydride and trimesic acid. Trivalent or higher polyvalent carboxylic acids having one acid anhydride group are preferred from the viewpoint of suppressing the reduction in molecular weight. Examples thereof include trimellitic anhydride and hydrogenated trimellitic anhydride. is preferably trimellitic anhydride from the viewpoint of low dielectric loss tangent.
The temperature in the depolymerization is usually 200-260° C., and the reaction time is usually 10 minutes-3 hours.

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

[Glass transition temperature (Tg) of polyester resin]
The glass transition temperature (Tg) of the polyester resin used in the present invention is −5° C. or higher, preferably 0 to 70° C., more preferably 5 to 60° C., particularly preferably 10 to 50° C., still more preferably 12. ~40°C, most preferably 15-30°C.
If the glass transition temperature (Tg) is too low, initial adhesiveness and tack-free properties will be insufficient. 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.

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

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 = 9/1 by volume) and performing neutralization titration based on JIS K0070. can.
In addition, in the present invention, the acid value of the polyester resin is due to the content of carboxy groups in the resin.

[Ester bond concentration of polyester resin]
The ester bond concentration of the polyester resin used in the present invention is preferably 8 mmol/g or less, more preferably 2 to 7.5 mmol/g, still more preferably 2.5 to 7 mmol/g, particularly preferably 3 to 6.5 mmol/g, particularly preferably 3.5 to 6 mmol/g.
If the ester bond concentration is too high, the low hygroscopicity tends to be insufficient, and if the ester bond concentration is too low, the initial adhesiveness tends to be insufficient.

The definition and 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, still more preferably 0.5 mmol/g or less. It is 5 mmol/g or less, and most preferably 0.2 mmol/g or less.
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, most preferably 0.5 mmol/g or less. 5 mmol/g or less. Also, 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 0.2 mmol/g. / g or less.

[Peak top molecular weight (Mp) and weight average molecular weight (Mw) of polyester resin]
The peak top molecular weight (Mp) of the polyester resin 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 50,000.
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 used in the present invention is preferably 10,000 to 300,000, more preferably 20,000 to 200,000, particularly preferably 30,000 to 150,000, still more preferably 40,000 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 of polyester resin (% by weight)]
The water absorption rate of the polyester resin 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 still more preferably 0.6% by weight or less.
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 the curing agent is added) is 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. Six pieces of this sheet are cut into a size of 7.5 cm x 11 cm. Next, after peeling off the release film of the cut sheet and laminating these sheets, one polyester resin layer surface of the sheet is laminated on the glass plate to form a polyester resin layer having a thickness of 390 μm on the glass plate. Obtain a test panel with
The test plate thus obtained was immersed in purified water at 23° C. for 24 hours, then taken out, the water on the surface was wiped off, and dried at 70° C. for 2 hours. The weight required in each of these steps is measured, and the water absorption (% by weight) is calculated from the change in weight according to the following formula.
Water absorption (% by weight) = (cd) x 100/(ba)
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

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

(Dielectric loss tangent (Df))
The dielectric loss tangent at a frequency of 10 GHz in an environment of a temperature of 23° C. and a relative humidity of 50% RH of the polyester resin used in the present invention is 0.0050 or less, preferably 0.0045 or less, more preferably 0.0040 or less, It is particularly preferably 0.0035 or less, more preferably 0.0030 or less, particularly preferably 0.0025 or less, and most preferably 0.002 or less. If the dielectric loss tangent is too high, the transmission loss will increase when used as a substrate.

The dielectric constant and dielectric loss tangent can be measured by the cavity resonator perturbation method using a network analyzer. In addition, if it is difficult to prepare a measurement sample by itself due to the strong stickiness of polyester resin, it is also possible to measure it while sandwiching it between films and calculate the dielectric properties of the polyester resin alone by subtracting the film amount. can.

Thus, in the present invention, it is possible to obtain a polyester-based resin having a very small dielectric loss tangent as compared with the conventional ones.
A polyester-based resin having a very small dielectric loss tangent is very useful as a raw material for adhesives used for laminating electronic material members, etc., because it can suppress transmission loss in a high frequency region.

Further, in the present invention, a non-crystalline polyester resin is preferred from the viewpoint of solvent solubility and solution stability. Crystallinity tends to result in insufficient solvent solubility and solution stability.
Amorphous can be confirmed by a differential scanning calorimeter, for example, when measured at a temperature range of -70 to 400 ° C. and a temperature increase rate of 10 ° C./min, no endothermic peak due to crystal melting is observed. . Note that the measurement temperature range and temperature increase rate can be appropriately changed according to the sample.

In addition, in the present invention, it is preferable that the polyester resin is soluble in a non-halogen organic solvent from the viewpoint of the adhesive composition described below. Insufficient solubility in such an organic solvent tends to make preparation of the adhesive composition difficult.

Examples of the non-halogen organic solvent include aromatic solvents such as toluene, xylene, solvent naphtha and Solvesso, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl Examples include alcohol solvents such as alcohol, ester solvents such as ethyl acetate and normal butyl acetate, acetate solvents such as cellosolve acetate and methoxy acetate, and mixtures of two or more of these solvents.

<Curing agent>
The adhesive composition of the present invention preferably further contains a curing agent. By containing a curing agent, the functional group in the polyester resin reacts with the curing agent having a functional group that reacts with the functional group, and the adhesive is cured and has excellent adhesive strength, heat resistance, and durability. can be obtained.
Examples of such curing agents include compounds having functional groups that react with at least one of hydroxyl groups and carboxy groups contained in polyester resins, such as polyisocyanate compounds and polyepoxy compounds. It is preferable that it is a polyepoxy-based compound.

Examples of the polyisocyanate-based compound include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate. Moreover, isocyanate adducts such as tolylene diisocyanate adducts, hexamethylene diisocyanate adducts, and isophorone diisocyanate adducts of trimethylolpropane can also be used. The above polyisocyanate-based compound may also be one in which the isocyanate portion is blocked with phenol, lactam, or the like. These isocyanate compounds may be used singly or in combination of two or more.

Examples of the polyepoxy compound include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; Glycidyl ether type; glycidyl ester type such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; Aliphatic epoxides and the like can be mentioned. One or more of these polyepoxy compounds can be used. Among them, glycidyl ether type and glycidyl ester type are preferred from the viewpoint of reactivity, glycidyl ether type is preferred from the viewpoint of wet heat durability, and polyfunctional type is preferred from the viewpoint of solder heat resistance.

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

Furthermore, when a nitrogen atom-containing polyepoxy compound (nitrogen atom-containing polyepoxy compound) is contained as the polyepoxy compound, the coating film of the adhesive composition is brought to the B stage (half-stage) by heating at a relatively low temperature. 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, and the polyepoxy compound contains these nitrogen atom-containing polyepoxy compounds, the content of the nitrogen atom-containing polyepoxy compound is It is preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less based on the entire epoxy compound. In addition, the content of such a nitrogen atom-containing polyepoxy compound is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight or less with respect to 100 parts by weight of the polyester resin. is.
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 0.7-5, more preferably 0.8-3, particularly preferably 0.9-2.5, still more preferably 1-2.
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 carboxyl group (COOH) is obtained from the acid value of the polyester resin and the epoxy equivalent weight (g/eq) of the blended polyepoxy compound by the following formula.
Equivalent weight of epoxy to COOH=(a÷WPE)/(AV÷56.1÷1000×b)
a: Weight (g) of polyepoxy compound used in formulation
WPE: Epoxy equivalent weight (g/eq) of polyepoxy compound
AV: Acid value of polyester resin (mgKOH/g)
b: Weight (g) of polyester resin used for blending

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

In the adhesive composition of the present invention, a filler, a flame retardant, etc. may be blended. 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.

Further, when the adhesive composition of the present invention contains a curing agent, the content of the curing agent is preferably 1 to 30 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the polyester resin of the present invention. 20 parts by weight, particularly preferably 3 to 15 parts by weight, more preferably 4 to 10 parts by weight. If the content of the curing agent is too low, the heat resistance and long-term durability in a hot and humid environment will tend to be insufficient. tend to

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. 1 minute to 10 hours at .

A catalyst may be used when curing the adhesive composition of the present invention using a curing agent.
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 with respect to 100 parts by weight of the polyester resin. Within this range, the catalytic effect for the reaction between the polyester-based resin and the curing agent 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.

Aromatic ring content, alicyclic content, glass transition temperature (°C), acid value (mgKOH/g), ester bond concentration (mmol/g), peak top molecular weight (Mp), weight average molecular weight (Mw), dielectric properties , the equivalent weight of epoxy groups to COOH was measured as described herein. Methods for measuring other physical properties are as follows.

[Dimer diol content]
Shows the content (%) of dimer diol with respect to the polyester resin.

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

[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 263.7 parts (1.5872 mol) of isophthalic acid (IPA) and 3 trimellitic anhydride (TMAn) as polyvalent carboxylic acids. .1 part (0.0161 mol), 105.0 parts (0 .3221 mol), ethylene glycol (EG) 65.0 parts (1.0472 mol), dimer diol "PRIPOL 2033" (P2033) (manufactured by Croda) 234.5 parts (0.4431 mol), neopentyl glycol ( NPG) 62.9 parts (0.6039 mol) and 0.1 part of tetrabutyl titanate as a catalyst were charged, the temperature was raised over 2.5 hours until the internal temperature reached 270°C, and the temperature was increased to 270°C for 1.5 hours. , an esterification reaction was carried out.
Then, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure in the system was reduced to 2.5 hPa, and the polymerization reaction was carried out over 2 hours.
Thereafter, the inner temperature is lowered to 230°C, 15.8 parts (0.0822 mol) of trimellitic anhydride (TMAn) is added, and depolymerization reaction is performed at 230°C for 1 hour to obtain a polyester resin (A-1). got

[Production of polyester resins (A-2 to 12, A'-1 to 2)]
Polyester resins (A-2 to 12, A'-1 to 2) were obtained in the same manner as A-1, except that the resin composition was changed as shown in Table 1.

Table 2 shows the resin composition (structural units derived from components) and physical properties of the obtained polyester-based resin. In addition, in Table 1, each abbreviation is as follows.
"NDCM": dimethyl naphthalene dicarboxylate "TPA": terephthalic acid "IPA": isophthalic acid "DMI": dimethyl isophthalate "P1009": dimer acid "Pripol 1009" (manufactured by Croda)
"TMAn": trimellitic anhydride "BPEF": bisphenoxyethanol fluorene "BOPPEF": bisphenylphenoxyethanol fluorene "BPE-20": about 2 moles of ethylene oxide of bisphenol A adduct "Newpol BPE-20" (Sanyo Kasei manufactured by Kogyosha)
"TCD-DM": tricyclodecanedimethanol "EG": ethylene glycol "2MPG": 2-methyl-1,3-propanediol "NPG": neopentyl glycol "1.4BG": 1.4-butanediol "1.6HG": 1,6-hexanediol "1.10DG": 1,10-decanediol "P2033": dimer diol "Pripol 2033" (manufactured by Croda)

<Curing agent>
As a curing agent, the following polyepoxy compound was prepared.
- Polyepoxy-based compound (B-1): phenol novolac type epoxy resin "YDPN-638" (manufactured by Nippon Steel Chemical & Materials Co., Ltd.) (epoxy equivalent = 177 (g / eq))
· Polyepoxy compound (B-2): glycidyl ether type special multifunctional epoxy resin "jER-1031S" (manufactured by Mitsubishi Chemical Corporation) (epoxy equivalent = 200 (g / eq))
- Polyepoxy compound (B-3): triglycidyl para-aminophenol "jER-630" (manufactured by Mitsubishi Chemical Corporation) (epoxy equivalent = 96 (g/eq))
- Polyepoxy compound (B-4): tetraglycidyldiaminodiphenylmethane "jER-604" (Mitsubishi Chemical Corporation) (epoxy equivalent = 120 (g/eq))

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

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

(Examples 2-7, Comparative Examples 1-2)
An adhesive composition was obtained in the same manner as in Example 1, except that the resin composition was as shown in Table 3.
The obtained adhesive composition was evaluated as follows, and the results are shown in Table 3.

<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, a rolled copper foil having a thickness of 30 μm is laminated with the adhesive layer surface of the polyimide film with an adhesive layer (lamination conditions: 170 ° C., 0.2 MPa, feed rate 1.5 m / min), and then heat treated in an oven at 160 ° C. for 4 hours. , to obtain a laminate.

[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 a temperature of 23 ° C. and a relative humidity of 50% RH (peeling speed: 50 mm/min, peeling angle: 180°). The evaluation criteria were as follows.
◎: 12 N / cm or more ○: 9 N / cm or more, less than 12 N / cm △: 6 N / cm or more, less than 9 N / cm ×: less than 6 N / cm

[Wet heat durability]
The laminate obtained above was placed in a thermo-hygrostat at a temperature of 85° C. and a relative humidity of 85% RH, taken out after a predetermined period of time, and allowed to stand overnight in an environment of a temperature of 23° C. and a relative humidity of 50% RH. The tensile peel strength was measured in the same manner as the initial adhesive strength described above. 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%

[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 to 3 above, the polyester resins (A-1) to (A-12) of Production Examples 1 to 12 satisfying the requirements of the present invention have a low dielectric constant and a low dielectric loss tangent, especially a low dielectric loss tangent. The adhesive compositions of Examples 1 to 7 obtained using them are excellent in initial adhesiveness after curing and further in long-term durability in a moist and hot environment.
On the other hand, the polyester resin (A'-1) of Comparative Production Example 1 is inferior in low dielectric loss tangent, and Comparative Example 1 obtained using it has initial adhesiveness after curing, and long-term durability in a moist and hot environment. It was inferior in terms of sex. The polyester resin (A'-2) of Comparative Production Example 2 was inferior in terms of low dielectric constant and low dielectric loss tangent.

The adhesive composition of the present invention is an adhesive composition containing a polyester-based resin, and has a low dielectric constant and a low dielectric loss tangent, particularly a low dielectric loss tangent. It has the effect of being excellent in long-term durability under the environment, and it is especially used as an adhesive for manufacturing metal and plastic laminates, such as flexible copper-clad laminates and flexible printed circuit boards. It is effective as an adhesive used.

Claims (10)

A polyester resin containing a structural unit derived from a polyhydric carboxylic acid and a structural unit derived from a polyhydric alcohol, wherein the polyhydric carboxylic acid contains an aromatic polyhydric carboxylic acid, and the polyhydric alcohol contains a dimer diol. Contains, has a glass transition temperature (Tg) of −5° C. or higher, an acid value of 3 mgKOH/g or higher, and a dielectric loss tangent (α) of 0.0050 at 10 GHz in an environment with a temperature of 23° C. and a relative humidity of 50% RH. A polyester resin characterized by: 2. The polyester resin according to claim 1, wherein the polyvalent carboxylic acid contains trivalent or higher polyvalent carboxylic acid having 0 or 1 acid anhydride group. 3. The polyester resin according to claim 1, wherein at least one of polyhydric carboxylic acids and polyhydric alcohols contains a condensed polycyclic aromatic compound. The polyester resin according to any one of claims 1 to 3 , which is amorphous. An adhesive composition comprising the polyester resin according to any one of claims 1 to 4 . 6. The adhesive composition according to claim 5 , further comprising a curing agent. 7. The adhesive composition according to claim 6 , wherein the content of the curing agent is 30 parts by weight or less with respect to 100 parts by weight of the polyester resin. An adhesive obtained by curing the adhesive composition according to claim 6 or 7 . 9. The adhesive according to claim 8 , which is used for bonding electronic material members. 10. The adhesive according to claim 9 , wherein the electronic material member is at least one selected from flexible copper-clad laminates, coverlays and bonding sheets.