JP2023176914A - Adhesive composition and adhesive - Google Patents

Abstract

To provide an adhesive composition having a low dielectric constant and a low dielectric loss tangent, and excellent in adhesiveness, and to provide an adhesive obtained by curing the adhesive composition.SOLUTION: An adhesive composition contains a polyester resin (A) having a structural site derived from polyvalent carboxylic acids (a1), and a structural site derived from polyhydric alcohols (a2). The adhesive composition is such that: a content of a structural site derived from aromatic polyvalent carboxylic acids (a1-1) is 20 mol% or more of the entire structural site derived from the polyvalent carboxylic acids (a1); and a content of a structural site derived from polydiene diols and/or hydrogenated polydiene diols (a2-1) is 50 wt.% or more of the entire polyester resin (A).SELECTED DRAWING: None

Description

The present invention relates to an adhesive composition containing a polyester resin and an adhesive obtained by curing this adhesive composition, and more specifically to an adhesive composition that has a low dielectric constant and a low dielectric loss tangent, and has excellent adhesive properties. The present invention relates to an adhesive composition and a cured adhesive composition thereof.

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.
Utilizing this property, adhesives for producing metal and plastic laminates, such as flexible copper-clad laminates and flexible printed circuit boards (hereinafter, both may be collectively referred to as FPC), etc. Its use as an adhesive is being considered.

Flexible copper-clad laminates and flexible printed circuit boards are a type of printed circuit board, and are made by laminating thin copper foil and insulating film (plastic film). FPC is flexible and can be repeatedly deformed, and can maintain its performance as a printed circuit board even after being deformed.
FPCs are thin and suitable for folding and use in moving parts, and demand is increasing as smartphones, televisions, notebook computers, and other electronic devices become smaller, lighter, and thinner in recent years.
Furthermore, with the recent increase in the speed of transmission signals and the increase in the frequency of transmission signals, low dielectric properties such as low dielectric constant and low dielectric loss tangent are required.

For example, Patent Document 1 discloses that a polyester resin containing a specific amount of a structural part having a polycyclic structure and a structural part having 10 or more consecutive carbon chains has excellent solvent solubility, heat resistance, adhesive strength. It is disclosed that the material has excellent dielectric properties such as excellent dielectric constant and low dielectric loss tangent.
Furthermore, in Patent Document 2, polyester having an ester group concentration of 5000 eq/106 g or less and a glass transition temperature of -30°C or higher has excellent solvent solubility, heat resistance, and adhesive strength, and has a low dielectric constant and dielectric loss tangent. It is disclosed that the material has low dielectric properties and excellent dielectric properties.

International Publication No. 2021/200715 International Publication No. 2021/200716

However, in recent years, in the field of electronic materials such as flexible copper-clad laminates and flexible printed circuit boards, lower dielectric properties such as lower dielectric constant and lower dielectric loss tangent are required as physical properties for adhesive layers used there. There is.

In the techniques disclosed in Patent Documents 1 and 2, the concentration of polar groups is lowered by using a monomer having 10 or more carbon chains in succession, resulting in a lower dielectric constant and lower dielectric loss tangent. If the polar group concentration is further lowered for the purpose of increasing the polarity, the adhesion tends to be significantly impaired, and it has been difficult to achieve both the high level of low dielectric properties and adhesion that have been required in recent years.

In view of this background, the present invention provides an adhesive composition that has a lower dielectric constant and a lower dielectric loss tangent, and also has excellent adhesive properties after curing, and an adhesive obtained by curing this adhesive composition. For the purpose of providing.

However, as a result of intensive research in view of the above circumstances, the present inventor found that the following adhesive composition met the object of the present invention, and completed the present invention.
That is, the gist of the present invention is an adhesive composition containing a polyester resin (A) having a structural part derived from a polyhydric carboxylic acid (a1) and a structural part derived from a polyhydric alcohol (a2),
The content of structural moieties derived from aromatic polyvalent carboxylic acids (a1-1) is 20 mol% or more of the total structural moieties derived from polyvalent carboxylic acids (a1),
The present invention relates to an adhesive composition in which the content of structural moieties derived from polydiene diols and/or hydrogenated polydiene diols (a2-1) is 50% by weight or more based on the entire polyester resin (A).

That is, the present invention has the following aspects [1] to [12].
[1]
An adhesive composition containing a polyester resin (A) having a structural part derived from a polyhydric carboxylic acid (a1) and a structural part derived from a polyhydric alcohol (a2),
The content of structural moieties derived from aromatic polyvalent carboxylic acids (a1-1) is 20 mol% or more of the total structural moieties derived from polyvalent carboxylic acids (a1),
An adhesive composition characterized in that the content of structural moieties derived from polydiene diols and/or hydrogenated polydiene diols (a2-1) is 50% by weight or more based on the entire polyester resin (A).
[2]
The adhesive composition according to item [1] above, wherein the polyester resin (A) has a dielectric loss tangent of 0.01 or less at a temperature of 23° C., a relative humidity of 50% RH, and a frequency of 10 GHz.
[3]
The adhesive composition according to [1] or [2] above, wherein the polyester resin (A) has a glass transition temperature of -60 to 60°C.
[4]
The adhesive composition according to any one of [1] to [3] above, wherein the polyester resin (A) has an acid value of 3 mgKOH/g or more.
[5]
An adhesive composition containing the polyester resin according to any one of [1] to [4] above, wherein at least one of the polyhydric carboxylic acids and the polyhydric alcohol contains a fused polycyclic aromatic compound. thing.
[6]
The method according to any one of [1] to [5] above, wherein the polyvalent carboxylic acids include trivalent or higher polyvalent carboxylic acids (a2-1) having an acid anhydride group of 0 or 1. An adhesive composition containing a polyester resin.
[7]
The adhesive composition according to any one of [1] to [6] above, wherein the polyester resin (A) is amorphous.
[8]
The adhesive composition according to claim 1 or 2, further comprising a curing agent (B).
[9]
9. The adhesive composition according to claim 8, wherein the content of the curing agent (B) is 30 parts by weight or less based on 100 parts by weight of the polyester resin.
[10]
An adhesive obtained by curing the adhesive composition according to claim 1 or 2.
[11]
The adhesive according to claim 10, which is used for bonding electronic material members.
[12]
12. The adhesive according to claim 11, wherein the electronic material member is at least one selected from a flexible copper-clad laminate, a coverlay, and a bonding sheet.

As in Patent Documents 1 and 2 above, in order to lower the dielectric constant and dielectric loss tangent, it is usually necessary to use a large amount of polyhydric carboxylic acids or polyhydric alcohols having long-chain alkyl groups to lower the ester bond concentration. This is possible, but on the other hand, the adhesive force will decrease. Moreover, it is difficult to obtain even lower dielectric properties by lowering the ester bond concentration.
The present inventor has discovered the unique effect of improving low dielectric properties and further improving adhesiveness by containing a specific amount or more of polybutadiene-derived structural moieties in a polyester resin, and has completed the present invention. .

The adhesive composition containing the polyester resin used in the present invention has a low dielectric constant and a low dielectric loss tangent, and forms an adhesive composition with excellent adhesive properties. , Adhesives for producing laminates of metal and plastic, for example, for bonding electronic materials, especially for producing flexible printed wiring boards such as flexible copper-clad laminates, coverlays, bonding sheets, etc. Effective as an adhesive.

The polyester resin used in the present invention has a specific amount or more of structural moieties derived from polydiene diols and/or hydrogenated polydiene diols and structural moieties derived from aromatic polycarboxylic acids, so that the effects of the present invention are not achieved. can get.

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

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

<Polyester resin (A)>
The polyester resin (A) used in the present invention contains structural units derived from polyhydric carboxylic acids (a1) and structural units derived from polyhydric alcohols (a2) in the molecule, and contains aromatic polycarboxylic The content of structural sites derived from acids (a1-1) is 20 mol% or more of the total structural sites derived from polyhydric carboxylic acids (a1),
Polydiene diols and/or hydrogenated polydiene diols (a2-1) (hereinafter, polydiene diols and/or hydrogenated polydiene diols (a2-1) are referred to as polydiene diols (a2-1) ) Hereinafter, the content of the derived structural site is 50% by weight or more of the entire polyester resin (A).

[Polyhydric carboxylic acids (a1)]
Examples of polyvalent carboxylic acids in the structural moiety derived from polyvalent carboxylic acids (a1) include aromatic polyvalent carboxylic acids (a1-1) described below; polycarboxylic acid (a1-2); alicyclic polycarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and its acid anhydride; succinic acid; Examples include aliphatic polycarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. One type or two or more types of polyhydric carboxylic acids can be used.

Examples of aromatic polycarboxylic acids (a1-1) include monocyclic aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl isophthalate, orthophthalic acid; biphenyldicarboxylic acid, naphthalene dicarboxylic acid, etc. polycyclic aromatic polycarboxylic acids such as dimethyl naphthalene dicarboxylate; among polycyclic aromatic polycarboxylic acids, fused polycyclic aromatic polycarboxylic acids such as naphthalene dicarboxylic acid and dimethyl naphthalene dicarboxylate; Examples include acids and their derivatives (aromatic dicarboxylic acids). Further examples include aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-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 are also included in the above-mentioned aromatic polycarboxylic acids. Examples of trifunctional or higher aromatic polycarboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, and pyrotrimellitic acid. 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 dianhydride Examples include anhydrides.
Among these, from the viewpoint of dielectric properties, polycyclic aromatic polycarboxylic acids are preferred, and among them, fused polycyclic aromatic polycarboxylic acids are particularly preferred. Among the fused polycyclic aromatic polycarboxylic acids, Particularly preferred is dimethyl naphthalene dicarboxylate.
Among the monocyclic aromatic polycarboxylic acids, terephthalic acid, dimethyl terephthalate, isophthalic acid, and dimethyl isophthalate are preferred.
Furthermore, in order to reduce crystallinity and ensure stability after dissolution in a solvent, it is preferable to use multiple types of polyhydric carboxylic acids.

The content of the structural unit derived from the aromatic polycarboxylic acid (a1-1) based on the entire polycarboxylic acid (a1) is 20 mol% or more, preferably 40 mol% or more, more preferably 70 mol% or more. , more preferably 90 mol% or more, particularly preferably 100 mol%. When the content of aromatic polyhydric carboxylic acids is within the above range, both excellent dielectric properties and adhesive properties can be achieved. On the other hand, if the amount is too low, long-term durability under a humid heat environment tends to be insufficient, and low dielectric loss tangent tends to be poor.

The content (mol %) of aromatic polycarboxylic acids based on the entire polycarboxylic acids is determined from the following formula.
Content of aromatic polyvalent carboxylic acids (mol%) = (aromatic polyvalent carboxylic acids (mol)/polyvalent carboxylic acids (mol)) x 100

Further, the content of structural moieties derived from aromatic polycarboxylic acids (a1-1) based on the entire polyester resin is preferably 1 to 50% by weight, more preferably 3 to 40% by weight, and still more preferably 5 to 50% by weight. ~30% by weight, particularly preferably 10-25% by weight. When the content of aromatic polycarboxylic acids is within the above range, both excellent dielectric properties and adhesive properties can be achieved. On the other hand, if it is too small, the initial adhesion will tend to be insufficient or the tackiness will become excessively strong, and if it is too large, the initial adhesion will tend to be insufficient.

When imparting an acid value to the polyester resin (A), a trivalent or higher polyvalent carboxylic acid (a1-2) having 0 or 1 acid anhydride group is used as a structural moiety derived from the polyvalent carboxylic acid (a1). From the viewpoint of adhesion, it is preferable to contain the structural site derived from the original structure. The valence of the carboxy group in the structural moiety derived from the trivalent or higher polyvalent carboxylic acids (a1-2) in which the number of acid anhydride groups is 0 or 1 is preferably 3 to 6, more preferably 3. -4 valence. Trivalent or higher polyvalent carboxylic acids having 0 or 1 acid anhydride group, which constitute the structural site derived from the trivalent or higher polyvalent carboxylic acids (a1-2) having 0 or 1 acid anhydride group; Examples of (a1-2) include those having 0 or 1 acid anhydride group among the above-mentioned trivalent or higher aromatic polycarboxylic acids. Examples include trimellitic anhydride, trimellitic acids, trimesic acids, and the like. In addition, examples of trivalent or higher polyhydric carboxylic acids (a1-2) having 0 or 1 acid anhydride group other than those mentioned above include hydrogenated trimellitic anhydride. Among these, those having one acid anhydride group are preferred, and structural moieties derived from trimellitic anhydride are particularly preferred.

Examples of the alicyclic polycarboxylic acids constituting the structural moiety derived from the alicyclic polycarboxylic acids include 1,4-cyclohexanedicarboxylic acids, 1,3-cyclohexanedicarboxylic acids, and 1,2-cyclohexanedicarboxylic acids. etc.

Examples of the aliphatic polycarboxylic acids constituting the structural moiety derived from the aliphatic polycarboxylic acids include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and the like.

When the polyester resin (A) contains a structural moiety derived from the alicyclic polycarboxylic acids and a structural moiety derived from the aliphatic polycarboxylic acids, the above structural moiety derived from the polycarboxylic acids (a1) is The total content of structural sites derived from alicyclic polycarboxylic acids and structural sites derived from aliphatic polycarboxylic acids is preferably 30 mol% or less, more preferably 20 mol% or less, particularly preferably It is 10 mol% or less.

The polyester resin (A) includes structural units derived from sulfoterephthalic acid, structural units derived from 5-sulfoisophthalic acids, structural units derived from 4-sulfophthalic acids, and structural units derived from 4-sulfonaphthalene-2,7-dicarboxylic acids. Structural units derived from aromatic dicarboxylic acids having sulfonic acid groups such as structural units derived from 5(4-sulfophenoxy)isophthalic acids, and aromatic compounds having sulfonic acid groups such as metal salts and ammonium salts thereof. Structural units derived from dicarboxylic acid salts may be included, but from the viewpoint of hygroscopicity of the polyester resin (A) and compatibility of the resin, the structural units derived from the polyhydric carboxylic acids (a1) may not be included in the entire structural units derived from the polyhydric carboxylic acids (a1). The amount is preferably 10 mol% or less, more preferably 5 mol% or less, particularly preferably 3 mol% or less, even more preferably 1 mol% or less, and most preferably 0 mol%.

[Structural site derived from polyhydric alcohol (a2)]
In the present invention, a structural unit derived from polydiene diol (a2-1) is contained as a structural moiety derived from polyhydric alcohol (a2).
The polydiene diol (a2-1) constituting the structural moiety derived from the polydiene diol (a2-1) is preferably a polydiene diol formed from a conjugated diene having 4 to 9 carbon atoms because of its excellent dielectric properties. Hydrogenated polydiene diols formed from diene diols and/or conjugated dienes having 4 to 9 carbon atoms are preferred, such as polybutadiene diols with hydroxyl groups at both ends, polyisoprene diols, polyhexadiene diols, etc. , and their hydrogenated products. These may be contained alone or in combination of two or more. Among them, hydrogenated polybutadiene diol is preferred from the viewpoint of suppressing gelation during production of the polyester resin (A).

The above-mentioned hydroxyl groups at both ends may be directly bonded to the polydiene structure or may be bonded via a bonding chain.
Such bonding chains include, for example, hydrocarbon chains such as alkylene chains, alkenylene chains, alkynylene chains, phenylene chains, and naphthylene chains (these hydrocarbons may be substituted with halogens such as fluorine, chlorine, and bromine). , -CO-, -COCO-, -CO(CH ₂ )mCO- (m=1 to 10), and the like. Among these, alkylene chains are preferred in that they do not inhibit the effects of the present invention. Moreover, the above-mentioned bonding chains may be contained alone or in combination of two or more types.

Further, the number average molecular weight of the polydiene diol (a2-1) is preferably 500 to 10,000, more preferably 600 to 5,000, from the viewpoint of excellent dielectric properties and compatibility with polyester. It is more preferably from 700 to 2,800, and particularly preferably from 800 to 1,800.

When the polydiene diol (a2-1) is a hydrogenated polydiene diol, the hydrogenation ratio is not particularly limited, but preferably 80% or more hydrogenation, particularly 90% or more hydrogenation. It is preferable to add it. If the hydrogenation rate is low, the appearance of the polyester resin (A) may deteriorate due to the unsaturated groups remaining, and gelation may easily occur during the production of the polyester resin (A). They tend to be difficult to manufacture. Further, the upper limit is usually 100%.

The polydiene diol preferably has a side chain, and the proportion of the side chain to the entire polydiene diol (a2-1) is preferably 10% or more, more preferably 20% or more, and further preferably 30% or more. Preferably, it is most preferably 40% or more.
The ratio of side chains to the total is determined by the following formula 1.
[Formula 1]
Ratio of side chains to the whole (%) = number of carbons in side chains / total number of carbons × 100

In the polyester resin (A) used in the present invention, from the viewpoint of dielectric properties and adhesive properties, it is necessary to include a structural moiety derived from polydiene diol (a2-1) in a structural moiety derived from polyhydric alcohol (a2). The amount is preferably 10 mol% or more, more preferably 15 to 90 mol%, still more preferably 20 to 80 mol%, particularly preferably 25 to 70 mol%. If the content of the structural moiety derived from polydiene diols (a2-1) is within the above range, low hygroscopicity, dielectric properties, and adhesive properties will be excellent; if it is too large, the adhesive property will be poor or the tackiness will be excessively high. On the other hand, if the amount is too low, the hygroscopicity, dielectric properties, and adhesiveness tend to be poor.

Furthermore, the content of structural moieties derived from polydiene diols and/or hydrogenated polydiene diols (a2-1) based on the entire polyester resin (A) is 50% by weight or more, preferably 55 to 95% by weight. %, more preferably 60 to 90% by weight, even more preferably 65 to 85% by weight. When the content of structural moieties derived from polydiene diols (a2-1) is within the above range, low hygroscopicity, excellent dielectric properties, and adhesive properties are achieved. If the amount is too large, the adhesiveness tends to be poor or the tackiness becomes excessively strong, whereas if the amount is too small, the hygroscopicity, dielectric properties, and adhesiveness tend to be poor.

Structural sites other than polydiene diols and/or hydrogenated polydiene diols (a2-1) include, for example, structural sites derived from dimer diols, structural sites derived from bisphenol skeleton-containing monomers, and structural sites derived from aliphatic polyhydric alcohols. (However, excluding polydiene diols and/or hydrogenated polydiene diols (a2-1).) Structural moieties derived from alicyclic polyhydric alcohols, structural moieties derived from aromatic polyhydric alcohols, etc. can be mentioned. The structural moiety derived from the polyhydric alcohol (a2) may be contained alone or in combination of two or more.

Furthermore, in the present invention, from the viewpoint of low dielectric loss tangent, the sum of the structural sites derived from the aromatic polycarboxylic acids (a1-1) and the structural sites derived from the polydiene diols (a2-1) is It is also preferable that the amount is 90% by weight or more of the resin (A). More preferably, it is 95% by weight or more.

The sum of the structural sites derived from the aromatic polycarboxylic acids (a1-1) and the structural sites derived from the polydiene diols (a1-2) can be determined by the following formula 2.
[Formula 2]
Total (wt%) of structural sites derived from polyvalent carboxylic acids (a1-1) and structural sites derived from polydiene diols (a2-1) = [structural sites derived from aromatic polyvalent carboxylic acids (a1-1) weight + weight of polydiene diol (a2-1)]/weight of entire polyester x 100

Examples of the dimer diols constituting the structural site derived from the dimer diols include dimer acids of unsaturated fatty acids having an average carbon number of 10 to 26 (preferably 12 to 24, more preferably 14 to 22). Examples include diols derived from. Specific examples include diols derived from unsaturated fatty acids such as oleic acids, linoleic acids, linolenic acids, and erucic acids.

Examples of bisphenol skeleton-containing monomers constituting structural sites derived from the bisphenol skeleton-containing monomer include bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, and bisphenol Z. , 4,4'-dihydroxybenzophenone, bisphenol fluorene, etc., hydrogenated products thereof, and 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. Examples include glycols.

Examples of the aliphatic polyhydric alcohol constituting the structural moiety derived from the aliphatic polyhydric alcohol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, and 2-methyl. -1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol , 2-ethyl-2-butylpropanediol, 2,4-diethyl-1,5-pentanediol, aliphatic diols such as 2,2,4-trimethyl-1,3-pentanediol, glycerin, trimethylolethane, Trimethyl or higher aliphatic polyhydric alcohols such as trimethylolpropane and pentaerythritol can be mentioned. Among them, ethylene glycol and trimethylolpropane are preferred.

Examples of the alicyclic polyhydric alcohol constituting the structural moiety derived from the alicyclic polyhydric alcohol include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, and tricyclodecanediol. Examples include candimethanol and spiroglycol.

The aromatic polyhydric alcohol constituting the structural moiety derived from the aromatic polyhydric alcohol is one excluding the bisphenol skeleton-containing monomer, and includes, for example, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4- Examples include phenylene glycol and ethylene oxide adducts of 1,4-phenylene glycol.

Further, examples of the aromatic polyhydric alcohol include fluorene diols represented by the following general formula (1).

式（１）中、Ｒ１は炭素数１～５のアルキレン基であり、例えば、メチレン基、エチレン基、プロピレン基、ブチレン基、ペンチレン基等が挙げられる。Ｒ２、Ｒ３、Ｒ４及びＲ５は水素原子、炭素数１～５のアルキル基、アリール基又はアラルキル基であり、これらは互いに同じであっても異なっていてもよい。

In formula (1), R1 is an alkylene group having 1 to 5 carbon atoms, such as a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and the like. R2, R3, R4 and R5 are a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an aryl group or an aralkyl group, and these may be the same or different.

The polyester resin (A) contains a structural site derived from dimer diols, a structural site derived from a bisphenol skeleton-containing monomer, a structural site derived from an aliphatic polyhydric alcohol, a structural site derived from an alicyclic polyhydric alcohol, and an aromatic polyhydric alcohol. If a structural site derived from a polyhydric alcohol (a2) is included, a structural site derived from a dimer diol, a structural site derived from a bisphenol skeleton-containing monomer, a structural site derived from an aliphatic polyhydric alcohol, The total content of structural moieties derived from alicyclic polyhydric alcohols and aromatic polyhydric alcohols is preferably 90 mol% or less, more preferably 80 mol% or less, particularly preferably 75 mol%. % or less.

In addition, when the polyester resin (A) contains a structural moiety derived from aliphatic polyhydric alcohol, the content of the structural moiety derived from aliphatic polyhydric alcohol in the structural moiety derived from polyhydric alcohol (a2) is , is preferably 90 mol% or less, more preferably 80 mol% or less, particularly preferably 75 mol% or less.

The polyester resin (A) used in the present invention has a structure derived from a trivalent or higher aromatic polycarboxylic acid and a structure derived from a trivalent or higher aliphatic polyhydric alcohol for the purpose of introducing a branched skeleton. In other words, as a copolymerization component of the polyester resin (A), the above trivalent or higher aromatic polycarboxylic acids and trivalent or higher aliphatic polycarboxylic acids have at least one structural moiety selected from the group consisting of moieties. It may contain at least one selected from the group consisting of alcohols. In particular, when forming a crosslinked structure by reacting with the curing agent (B) described below, the introduction of a branched skeleton increases the number of reaction points in the resin, making it possible to obtain a strong adhesive layer with a high crosslinking density. . Among these, trimethylolpropane is preferably included from the viewpoint of versatility. In addition, when using trivalent or higher polyvalent carboxylic acids (a1-2) having an acid anhydride group number of 0 or 1 in the depolymerization reaction described below, separately from the polyvalent carboxylic acids used in the depolymerization reaction, Aromatic polycarboxylic acids having a valence of 3 or more may also be used.

When using at least one selected from the group consisting of trivalent or higher aromatic polycarboxylic acids and trivalent or higher aliphatic polyhydric alcohols for the purpose of introducing a branched skeleton into the polyester resin (A), The content of aromatic polyhydric carboxylic acids with a valence of 3 or more based on the entire polyhydric carboxylic acids (a1), or the content of polyhydric alcohols with a valence of 3 or more with respect to the entire polyhydric alcohols (a2) The polyhydric carboxylic acids (a1-2) containing 0 or 1 acid anhydride group are each preferably 0.1 to 5 mol%, more preferably 0.3 to 3 mol%. The mol% is more preferably in the range of 0.5 to 2 mol%. If the content of both or either one is too large, the mechanical properties such as elongation at break of the coating film formed by applying the adhesive will decrease, and the adhesive strength will tend to decrease. It also has a tendency to gel.

Furthermore, the polyester resin (A) used in the present invention may contain a structural moiety derived from an oxycarboxylic acid compound.
The above-mentioned oxycarboxylic acid compound is a compound having a hydroxyl group and a carboxy group in its molecular structure.
Examples of the oxycarboxylic acid compounds constituting the structural moiety derived from the above oxycarboxylic acid compounds include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, and 6-hydroxy- Examples include 2-naphthoic acid and 4,4-bis(p-hydroxyphenyl)valeric acid. These may be used alone or in combination of two or more.

[Glass transition temperature (Tg) of polyester resin (A)]
The glass transition temperature (Tg) of the polyester resin (A) used in the present invention is preferably -60°C to 60°C, more preferably -55 to 40°C, particularly preferably -50 to 20°C, and The temperature is preferably -45 to 0°C, particularly preferably -40 to -20°C, and most preferably -35 to -25°C. If the glass transition temperature (Tg) is too low, the adhesion and dielectric properties tend to be poor, or the tackiness tends to be excessively strong; if the glass transition temperature (Tg) is too high, the adhesion tends to be insufficient. There is.

The method for measuring the glass transition temperature (Tg) is as follows.
Glass transition temperature (Tg) can be determined by measuring using a differential scanning calorimeter. The measurement conditions were a measurement temperature range of -90 to 100°C and a temperature increase rate of 10°C/min.

[Acid value of polyester resin (A)]
The acid value of the polyester resin (A) used in the present invention is preferably 3 mgKOH/g or more, more preferably 5 to 40 mgKOH/g, particularly preferably 6 to 30 mgKOH/g, even more preferably 7 to 20 mgKOH/g. It is.
When the acid value is within the above range, the degree of crosslinking when cured with a curing agent (B) such as epoxy, which will be described later, will be appropriate, resulting in good adhesion, heat resistance, low moisture absorption, and long-term durability in a moist heat environment. Excellent balance of properties and low dielectric properties. If the acid value is too low, when the adhesive composition contains a curing agent (B) such as a polyepoxy compound, there will be insufficient crosslinking points with the curing agent (B) and the degree of crosslinking will be low, resulting in poor heat resistance. becomes insufficient. In addition, if the acid value is too high, it may result in low hygroscopicity or poor long-term durability in a moist heat environment, or a large amount of curing agent (B) is required during curing, which has become increasingly required in recent years. It tends to be difficult to obtain low dielectric properties.

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 (A) 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 K 0070. It can be found by
In the present invention, the acid value of the polyester resin (A) is determined by the content of carboxy groups in the resin.

[Hydroxyl value of polyester resin (A)]
Further, the hydroxyl value of the polyester resin (A) is preferably 50 mgKOH/g or less, more preferably 20 mgKOH/g or less, even more preferably 10 mgKOH/g or less, particularly preferably 5 mgKOH/g or less. If the hydroxyl value is too high, the dielectric properties, particularly the dielectric loss tangent, tend to be poor.

The hydroxyl value of the polyester resin (A) is determined by neutralization titration based on JIS K 0070.

The ester group concentration of the polyester resin (A) is preferably 4.0 mmol/g or less, more preferably 1 to 3.5 mmol/g, even more preferably 1.5 to 3.0 mmol/g. It is g. If the ester group concentration is too low, the polarity and elastic modulus of the polyester resin (A) will decrease, resulting in poor adhesion or excessively strong tackiness, while if it is too high, it will adversely affect the dielectric properties. Tend.

The above-mentioned ester group concentration (mmol/g) refers to the number of moles of ester groups in 1 g of polyester resin (A), and is obtained, for example, from a calculated value from the amount charged. This calculation method is a value obtained by dividing the smaller number of moles of polyhydric carboxylic acids (a1) and polyhydric alcohol (a2) by the total weight of the finished product, and an example of the calculation formula is shown below. .
In addition, when the respective charged amounts of polyhydric carboxylic acid (a1) and polyhydric alcohol (a2) are the same molar amount, either of the following calculation formulas may be used.
Furthermore, if a monomer having both carboxylic acid and hydroxyl groups is used, or if polyester is prepared from caprolactone or the like, the calculation method will need to be changed as appropriate.

<When polycarboxylic acids (a1) are low>
Ester group concentration (mmol/g) = [(A1/α1×m1+A2/α2×m2+A3/α3×m3...)/Z]×1000
A: Amount (g) of polyhydric carboxylic acids (a1)
α: Molecular weight of polyvalent carboxylic acid (a1) m: Number of carboxy groups per molecule of polyvalent carboxylic acid (a1) Z: Finished weight (g)

<When polyhydric alcohol (a2) is low>
Ester group concentration (mmol/g) = [(B1/β1×n1+B2/β2×n2+B3/β3×n3...)/Z]×1000
B: Amount (g) of polyhydric alcohol (a2)
β: Molecular weight of polyhydric alcohol (a2) n: Number of hydroxyl groups per molecule of polyhydric alcohol (a2) Z: Finished weight (g)

Further, the ester group concentration can also be measured by a known method using NMR or the like. For example, the ester group concentration, composition, and composition ratio of polyester resin (A) can be determined by 1H-NMR measurement (proton type nuclear magnetic resonance spectroscopy) or 13C-NMR measurement (carbon type nuclear magnetic resonance spectroscopy) at a resonance frequency of 400 MHz. This can be done at

Further, the concentration of other polar groups other than the ester groups and reactive functional groups that the polyester resin (A) has 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 in the polyester resin (A) is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, and particularly preferably 1 mmol/g or less. It is not more than mmol/g, more preferably not more than 0.5 mmol/g, and most preferably not more than 0.2 mmol/g.

Examples of the ether group include alkyl ether groups and phenyl ether groups, and it is particularly preferable to reduce the concentration of alkyl ether groups from the viewpoint of low hygroscopicity and long-term durability in a moist heat environment.
The alkyl ether group concentration of the polyester resin (A) is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1.5 mmol/g or less, and even more preferably 1 mmol/g. /g or less, most preferably 0.5 mmol/g or less.
Further, the phenyl ether group concentration of the polyester resin (A) 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. It is 5 mmol/g or less.

The carbonate group concentration of the polyester resin (A) is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, and even more preferably 0.5 mmol/g. g or less, most preferably 0.2 mmol/
g or less.

[Weight average molecular weight (Mw) and peak top molecular weight (Mp) of polyester resin (A)]
The weight average molecular weight (Mw) of the polyester resin (A) used in the present invention is preferably 5,000 to 500,000, more preferably 10,000 to 400,000, particularly preferably 20,000 to 300,000, still more preferably 30,000 to 250,000, and especially Preferably it is 50,000 to 200,000.
If the weight average molecular weight (Mw) is too low, low hygroscopicity, long-term durability in a moist heat environment, and low dielectric properties tend to be insufficient. Furthermore, if the weight average molecular weight (Mw) is too high, the adhesive strength may be insufficient or the solution viscosity during coating may be too high, making it difficult to obtain a uniform coating film.

The peak top molecular weight (Mp) of the polyester resin (A) used in the present invention is preferably 5,000 to 150,000, more preferably 10,000 to 120,000, particularly preferably 15,000 to 100,000, even more preferably 20,000 to 80,000.
If the peak top molecular weight (Mp) is too low, low hygroscopicity, long-term durability in a moist heat environment, and low dielectric properties tend to be insufficient. Furthermore, if the peak top molecular weight (Mp) is too high, the adhesive strength may be insufficient or the solution viscosity during coating may be too high, making it difficult to obtain a uniform coating film.

The weight average molecular weight (Mw) and peak top molecular weight (Mp) were measured as follows.
The weight average molecular weight (Mw) and peak top molecular weight (Mp) were measured using a high performance liquid chromatograph (Japan Waters Co., Ltd., "Waters 2695 (main body)" and "Waters 2414 (detector)"), column: Shodex GPC KF- 806L (exclusion limit molecular weight: 2×10 7 , separation range: 100 to 2×10 7 , number of theoretical plates: 10,000 plates/piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm) at 3 It can be measured by placing books in series and converting it to a 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. Note that the lower limit is usually 0% by weight.
If the water absorption rate is too high, wet heat durability and insulation reliability tend to decrease, and dielectric properties tend to deteriorate.

The method for measuring the water absorption rate is as follows.
A polyester resin (A) solution (not containing the curing agent (B) described below) was applied onto the release film using an applicator and dried at 120°C for 10 minutes, resulting in a dry film thickness of the polyester resin (A) layer of 65 μm. Create a sheet. This sheet is cut into a size of 7.5 cm x 11 cm, and the polyester resin (A) layer side of the sheet is laminated onto a glass plate whose weight has been measured in advance, and then the release film is peeled off. By laminating six of these polyester resin (A) layers, a test plate having a 390 μm thick polyester resin layer on a glass plate is obtained, and its weight is measured.
The test plate obtained in this manner was immersed in purified water at 23°C for 24 hours, then taken out, the surface moisture was wiped off, the weight was measured, and the test plate was dried at 70°C for 2 hours. Measure the weight of. From the weight measured in each of these steps, the water absorption rate (weight %) is calculated according to the following formula 3.
[Formula 3]
Water absorption rate (weight%) = (c-d)/(ba) x 100
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

[Dielectric properties of polyester resin (A)]
(Dielectric constant (Dk))
The dielectric constant of the polyester resin (A) used in the present invention at a frequency of 10 GHz at a temperature of 23° C. and a relative humidity of 50% RH is preferably 2.6 or less, more preferably 2.4 or less, particularly preferably 2. .3 or less, more preferably 2.2 or less. If the dielectric constant is too high, the transmission speed tends to be poor and the transmission loss tends to be large.

(Dielectric loss tangent (Df))
The dielectric loss tangent of the polyester resin (A) used in the present invention at a frequency of 10 GHz at a temperature of 23° C. and a relative humidity of 50% RH is preferably 0.01 or less, more preferably 0.005 or less, and even more preferably 0. It is .003 or less, particularly preferably 0.0025 or less, further preferably 0.002 or less, particularly preferably 0.0018 or less, and most preferably 0.0015 or less. If the dielectric loss tangent is too high, transmission loss tends to increase.

The above dielectric constant and dielectric loss tangent can be measured by a cavity resonator perturbation method using a network analyzer. If the polyester resin (A) is so sticky that it is difficult to prepare a measurement sample by itself, measure it by sandwiching it in a film and subtract the amount of the film to determine the dielectric strength of the polyester resin (A) alone. Properties can also be calculated.

[Probe tack (N) of polyester resin (A)]
The probe tack of the polyester resin (A) used in the present invention is preferably 5N or less, more preferably 3N or less, particularly preferably 2N or less, still more preferably 1.5N or less. Note that the lower limit is usually 0N.
If the probe tack is too high, the adhesiveness is strong, and when it is made into an adhesive sheet, handling and reworkability tend to be poor, and problems tend to occur in the processing process of flexible printed wiring boards.

The method for measuring the probe tack is as follows.
A polyester resin (A) solution (not containing the curing agent (B) described below) was applied onto a 38 μm thick PET film (Toray Industries, Inc., "Lumirror T60") using an applicator, dried at 120°C for 5 minutes, and the polyester A sheet with a dry thickness of the resin (A) layer of 25 μm is prepared. Next, the sheet was cut into a size of 12 mm x 12 mm, and tested in an environment of 23° C. and 50% RH using a probe tack tester (manufactured by Tester Sangyo Co., Ltd., TE-6001) with a probe diameter of 5 mmΦ and a pushing speed of 10 mm/ sec, a pulling speed of 10 mm/sec, a pressurizing time of 5 seconds, and a pasting pressure of 1000 gf/cm ² .

Further, in the present invention, it is preferable that the polyester resin (A) is an amorphous polyester resin in terms of solvent solubility and solution stability.
If crystalline, solvent solubility and solution stability tend to be insufficient.
Amorphousness can be confirmed using a differential scanning calorimeter, for example, when an endothermic peak due to crystal melting is not observed when measured at a temperature range of -90 to 400°C and a temperature increase rate of 10°C/min. say. Note that the measurement temperature range and temperature increase rate can be changed as appropriate depending on the sample.

[Manufacture of polyester resin (A)]
The polyester resin (A) of the present invention is produced by using the above-mentioned polyhydric carboxylic acids (a1) and the above-mentioned polyhydric alcohols (a2) as raw materials and subjecting them to a polycondensation reaction by a known method in the presence of a catalyst. be able to. That is, since the polyester resin (A) is obtained by polycondensation reaction of polycarboxylic acids (a1) and polyhydric alcohols (a2), the structural moieties derived from polycarboxylic acids (a1) and polyhydric alcohols are It has a structural part derived from the alcohol (a2). In the above polycondensation reaction, an esterification reaction or a transesterification reaction is first performed, and then a polycondensation reaction is performed. In addition, if it is not necessary to have a high molecular weight, it may be produced only by esterification reaction or transesterification reaction.

The blending ratio of the polyhydric carboxylic acid (a1) and polyhydric alcohol (a2) is preferably 1 to 3 equivalents of the polyhydric alcohol (a2) per 1 equivalent of the polyhydric carboxylic acid (a1). , particularly preferably 1.1 to 2.2 equivalents, and even more preferably 1.2 to 1.7 equivalents. If the blending ratio of polyhydric alcohol (a2) is too low, the acid value will tend to be high and it will be difficult to increase the molecular weight, and if it is too high, the yield will tend to decrease.

[Esterification reaction or transesterification reaction]
In the esterification reaction or transesterification reaction, a catalyst is usually used, and specifically, for example, a titanium-based catalyst such as tetraisopropyl titanate or tetrabutyl titanate, an antimony-based catalyst such as antimony trioxide, germanium dioxide, etc. Examples include catalysts such as germanium-based catalysts, zinc acetate, manganese acetate, dibutyltin oxide, etc., and one or more of these may be used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the viewpoint of the balance between high catalytic activity and color of the resulting reaction product.

The amount of the catalyst blended is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm based on the total copolymerization components (by weight). If the amount is too small, the polymerization reaction tends to be difficult to proceed sufficiently, and if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

The reaction temperature during the esterification reaction or transesterification reaction is preferably 200 to 300°C, particularly preferably 210 to 280°C, and even more preferably 220 to 260°C. If the reaction temperature is too low, the reaction tends to be difficult to proceed sufficiently, whereas if it is too high, side reactions such as decomposition tend to occur. Further, the pressure during the reaction is usually normal pressure, but it is also preferable to carry out the reaction under pressure to increase the reaction temperature and proceed with the reaction efficiently.

As for the reaction conditions for the polycondensation reaction that is carried out after the above esterification reaction or transesterification reaction, the same catalyst as that used in the above esterification reaction or transesterification reaction is further blended in the same amount. However, it is preferable that the reaction temperature is preferably 220 to 280°C, particularly preferably 230 to 270°C, and the pressure of the reaction system is gradually reduced to finally carry out the reaction at 5 hPa or less. If the reaction temperature is too low, the reaction tends to be difficult to proceed sufficiently, whereas if it is too high, side reactions such as decomposition tend to occur.

In addition, when obtaining a polyester resin having a carboxyl group in the side chain, a hydroxyl group-containing resin obtained by copolymerizing a polyhydric carboxylic acid (a1) other than a polyhydric carboxylic acid anhydride and a polyhydric alcohol (a2) is used. A method in which a prepolymer is reacted with a polyhydric carboxylic acid anhydride is preferred from the viewpoint of productivity.

The temperature in the esterification reaction between polyhydric carboxylic acids (a1) and polyhydric alcohols (a2) is usually 180 to 280°C, and the reaction time is usually 60 minutes to 8 hours.

The temperature in polycondensation is usually 200 to 280°C, and the reaction time is usually 20 minutes to 4 hours. Moreover, it is preferable to perform polycondensation under reduced pressure.

In addition, the polyester resin (A) can be prepared by a well-known method other than the above, for example, by combining polycarboxylic acids (a1) and polyhydric alcohols (a2) into esters in the presence of a catalyst if necessary. After obtaining a prepolymer through a chemical reaction, it can be produced by performing polycondensation and further depolymerization.

In the depolymerization, it is preferable to use trivalent or higher polyhydric carboxylic acids (a1-2) having 0 or 1 acid anhydride group from the viewpoint of adhesive strength. As the trivalent or higher polyvalent carboxylic acids (a1-2) having 0 or 1 acid anhydride group, those explained for the polyvalent carboxylic acids (a1) can be used. Among these, preferred are trivalent or higher polyhydric carboxylic acids (a1-2) having an acid anhydride group of 1 from the viewpoint of suppressing molecular weight reduction, and more preferred are trimellitic anhydride and hydrogenated trivalent carboxylic acids (a1-2). Mellitic acid anhydride is particularly preferred, and trimellitic acid anhydride is particularly preferred from the viewpoint of low dielectric loss tangent.
The temperature during depolymerization is usually 200 to 260°C, and the reaction time is usually 10 minutes to 3 hours.

During depolymerization, when the total amount of polyvalent carboxylic acids (a1) is 100 mol%, 20 mol% of trivalent or higher polyvalent carboxylic acids (a1-2) having an acid anhydride group of 0 or 1 is added. If the amount is exceeded, the molecular weight of the resin may decrease significantly. Therefore, the entire polyhydric carboxylic acid (a1) is 1
When the number of acid anhydride groups is 0 or 1, the depolymerization is preferably carried out using 20 mol% or less of trivalent or higher polyhydric carboxylic acids (a1-2), more preferably 1 The content is preferably 15 to 15 mol%, particularly preferably 2 to 10 mol%, and even more preferably 3 to 8 mol%.

In this way, it is possible to obtain a polyester resin (A) having a very small dielectric loss tangent compared to the conventional one.
The polyester resin (A), which has a very small dielectric loss tangent, is very useful as a raw material for adhesives used for bonding electronic material members, etc., since it can suppress transmission loss in a high frequency range.

Further, in the present invention, it is preferable that the polyester resin (A) is soluble in a non-halogen organic solvent from the viewpoint of forming the adhesive composition described below. Insufficient solubility in such organic solvents tends to make it difficult to prepare adhesive compositions.

Examples of the non-halogen organic solvents 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, and isobutyl These include alcohol solvents such as alcohol, ester solvents such as ethyl acetate and n-butyl acetate, acetate solvents such as cellosolve acetate and methoxy acetate, and mixtures of two or more of these solvents.

[Curing agent (B)]
It is preferable that the adhesive composition of the present invention further contains a curing agent (B). By containing the curing agent (B), the functional groups in the polyester resin (A) react with the curing agent (B) having a functional group that reacts with such functional groups, and are cured, resulting in improved adhesive strength and heat resistance. An adhesive with excellent properties and durability can be obtained. Furthermore, like polyfunctional acrylate, the curing agents may react with each other and form entanglements with the polyester resin (A), resulting in pseudo-crosslinking.
Examples of the curing agent (B) include polyisocyanate compounds, polyepoxy compounds, polyfunctional (meth)acrylic monomers, and polyfunctional urethane (meth)acrylates, among which polyester resins (A ) is preferable, and a compound having a functional group that reacts with at least one of a hydroxyl group and a carboxy group contained in the above is preferable, and among them, a polyepoxy compound is preferable from the viewpoint of soldering heat resistance.

Examples of the polyisocyanate compounds include tolylene diisocyanate curing agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylylene diisocyanate curing agents such as 1,3-xylylene diisocyanate, Diphenylmethane curing agents such as diphenylmethane-4,4-diisocyanate, aromatic isocyanate curing agents such as naphthalene diisocyanate curing agents such as 1,5-naphthalene diisocyanate; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4 Alicyclic isocyanate curing agents such as '-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, norbornane diisocyanate; hexamethylene diisocyanate, trimethyl hexa Aliphatic isocyanate curing agents such as methylene diisocyanate; examples include adducts, bullets, and isocyanurates of the above-mentioned isocyanate compounds. In addition, the above polyisocyanate-based compounds can also be used even if the isocyanate moiety is blocked with phenol, lactam, or the like. These polyvalent isocyanate compounds may be used alone or in combination of two or more. Among these, from the viewpoint of compatibility, alicyclic isocyanate curing agents and aliphatic isocyanate curing agents are preferable, and alicyclic isocyanate curing agents are particularly preferable, and furthermore, isocyanurates of isophorone diisocyanate and Adduct bodies are preferred.

The equivalent weight of isocyanate groups to hydroxyl groups (functional group molar ratio) is preferably 0.2 to 5, more preferably 0.3 to 3, particularly preferably 0.5 to 2, and even more preferably 1.0 to 1.6. It is.
If the amount is too large, the adhesive strength and stability over time of the adhesive sheet tend to be insufficient. On the other hand, if it is too small, the long-term durability and cohesive force in a moist heat environment tend to be insufficient, and the dielectric properties tend to be poor.

Examples of the polyepoxy compounds include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; polyfunctional glycidyl ether types such as phenol novolac glycidyl ether and cresol novolac glycidyl ether. Glycidyl ether type; Glycidyl ester type such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; Examples include aliphatic epoxides. One type or two or more types of these polyepoxy compounds can be used. Among these, 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 heat resistance.

Further, the epoxy equivalent of the polyepoxy compound is preferably 500 g/eq or less, more preferably 350 g/eq or less, particularly preferably 250 g/eq or less, still more preferably 200 g/eq or less. If the epoxy equivalent of the polyepoxy compound is too large, the crosslinking density after crosslinking will be low, resulting in poor heat resistance, and it will be necessary to add a large amount of polyepoxy compound to increase the crosslinking density, resulting in poor dielectric properties. There is.

Furthermore, it is preferable to contain a polyepoxy compound containing a nitrogen atom (nitrogen atom-containing polyepoxy compound) as the polyepoxy compound, since the curing time of the adhesive layer can be shortened.

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 type compounds.

The equivalent weight (functional group molar ratio) of the epoxy group to the carboxyl group is preferably 0.5 to 5, more preferably 0.8 to 3, particularly preferably 0.9 to 2, and still more preferably 1 to 1.5. be.
If the amount is too large, adhesive strength and low moisture absorption properties tend to be insufficient, and dielectric properties tend to be poor. Moreover, if it is too small, long-term durability and heat resistance under a moist heat environment tend to be insufficient.

The equivalent weight (functional group molar ratio) of the epoxy group to the carboxyl group (COOH) is determined by the following formula 4 from the acid value of the polyester resin (A) and the epoxy equivalent (g/eq) of the blended polyepoxy compound. It will be done.
[Formula 4]
Equivalent weight of epoxy to COOH = (a÷WPE)/(AV÷56.1÷1000×b)
a: Weight (g) of polyepoxy compound used in blending
WPE: Epoxy equivalent weight (g/eq) of polyepoxy compound
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 a polyester resin (A) and, if necessary, a curing agent (B) and other components.
In the adhesive composition of the present invention, the content of the polyester resin (A) is preferably 30% by weight or more, more preferably 50% by weight or more, particularly preferably 60% by weight based on the entire solid content. The content is more preferably 70% by weight or more. Note that the upper limit is usually 99% by weight.
Within the above content range, the effects of the present invention can be more easily obtained.

When the adhesive composition of the present invention contains a curing agent (B), the content of the curing agent (B) is preferably 30 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of the polyester resin (A). is 0.1 to 20 parts by weight, particularly preferably 0.5 to 10 parts by weight, and even more preferably 1 to 5 parts by weight. If the content of the curing agent (B) is too low, the heat-resistant adhesive strength and long-term durability in a moist heat environment will tend to be insufficient, and if it is too high, the adhesive strength and low moisture absorption will be insufficient. Dielectric properties tend to be poor.

[Other ingredients]
The adhesive composition of the present invention may contain components other than the polyester resin (A) and the curing agent (B) 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 The amount is preferably 0.1 to 50% by weight, more preferably 0.2 to 40% by weight.

The adhesive composition of the present invention can be prepared, for example, by preparing the polyester resin (A) and any necessary optional components, and mixing and dispersing the polyester resin (A) at the time of manufacturing the polyester resin (A), or by dissolving the polyester resin (A) in an organic solvent. It can be obtained by adding it to a solution of the resin (A) and dispersing it using a mixing roller or the like.

Furthermore, 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 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.

<Adhesive>
In the present invention, an adhesive can be obtained by curing the adhesive composition.
"Curing" in the present invention means intentionally crosslinking the adhesive composition by heat and/or light, and the degree of crosslinking can be controlled depending on desired physical properties and use.

The degree of crosslinking can be confirmed by the gel fraction of the adhesive, and preferably the gel fraction is 30% by weight or more, more preferably 40% by weight or more, particularly preferably 50% by weight or more, and even more preferably 60% by weight. That's all. If the gel fraction is too low, heat resistance and long-term durability in a moist heat environment will tend to be insufficient, and if it is too high, the adhesive strength will tend to be insufficient.
Note that the above gel fraction serves as a guideline for the degree of curing, and is calculated, for example, by the following method. That is, an adhesive sheet (without a release sheet) consisting of a polymer sheet (such as PET film) as a base material and an adhesive layer formed thereon is wrapped in a 200-mesh SUS wire mesh and placed in toluene. The wire gauze is immersed at 23°C for 24 hours, and the weight percentage of the undissolved adhesive component remaining in the wire gauze after immersion is defined as the gel fraction relative to the weight of the adhesive component before immersion. However, the weight of the base material should be deducted.

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. Examples of heating conditions include 1 minute to 10 hours.

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, 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-diazabicyclo Tertiary amines such as (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(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., have thermosetting and heat-resistant properties. It is preferable in terms of properties, 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. Within this range, the catalytic effect on the reaction between the polyester resin (A) and the curing agent (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 under moist heat environments, so it is effective for bonding base materials 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, an adhesive used for bonding electronic material members.
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.

<Example 1>
[Production of polyester resin (A-1)]
7.5 parts (0.039 mol) of dimethyl terephthalate (a1-1) and dimethyl isophthalate as polycarboxylic acids (a1) were placed in a reaction vessel equipped with a thermometer, stirrer, rectification column, and nitrogen inlet tube. (a1-1) 8.8 parts (0.045 mol), dimethyl 2,6-naphthalene dicarboxylate (a1-1) 9.4 parts (0.039 mol), trimellitic anhydride (a1-2) 1 .2 parts (0.006 mol), 9.6 parts (0.155 mol) of ethylene glycol as polyhydric alcohol (a2), hydrogenated polybutadiene diol (a2-1) with a number average molecular weight of 3870 (GI-3000 ( Nippon Soda Co., Ltd.) 473.6 parts (0.122 mol) and 0.1 part of tetrabutyl titanate as a catalyst were added, and the temperature was raised over 2.5 hours until the internal temperature reached 270°C. The esterification reaction was carried out for .5 hours.
Next, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure inside the system was reduced to 2.5 hPa, and a polymerization reaction was carried out over 2 hours.
Thereafter, the internal temperature was lowered to 230°C, 9.9 parts (0.052 mol) of trimellitic acid anhydride (TMAn) was added, and a depolymerization reaction was carried out at 230°C for 1 hour to form a polyester resin (A-1). I got it.

<Examples 2 to 4 and Comparative Example 1>
[Production of polyester resins (A-2) to (A-4), (A'-1)]
Polyester resins (A-2) to (A-4) and (A'-1) were prepared in the same manner as polyester resin (A-1) except that the resin composition was changed as shown in Table 1. Obtained.

<Comparative example 2>
[Production of polyester resin (A'-2)]
Into a reaction vessel equipped with a thermometer, stirrer, rectification column, and nitrogen inlet tube, 19.3 parts (0.132 mol) of adipic acid and 17.1 parts (0.1 mol) of sebacic acid were added as polycarboxylic acids (a1). 084 mol), 13.4 parts (0.217 mol) of ethylene glycol as polyhydric alcohol (a2), hydrogenated polybutadiene diol (a2-1) with a number average molecular weight of 2300 (GI-2000 (manufactured by Nippon Soda)) 448.2 parts (0.195 mol), 2.0 parts (0.015 mol) of trimethylolpropane, and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the mixture was heated for 2.5 hours until the internal temperature reached 270°C. The temperature was raised to 270° C. for 1.5 hours to carry out the esterification reaction.
Next, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure inside the system was reduced to 2.5 hPa, and a polymerization reaction was carried out over 2 hours to obtain a polyester resin (A'-2).

<Comparative Examples 3 and 4>
[Production of polyester resin (A'-3) (A'-4)]
Polyester resins (A'-3) and (A'-4) were obtained in the same manner as polyester resin (A'-2) except that the resin composition was changed as shown in Table 1.

The composition described in Table 1 below is the finished composition ratio (resin composition ratio), and is the relative ratio (mole ratio) of the amount of each constituent monomer of the obtained polyester resin. In addition, in Table 1, each abbreviation is as follows.
"IPA": Isophthalic acid (a1-1)
[DMT”: dimethyl terephthalate (a1-1)
"DMI": dimethyl isophthalate (a1-1)
"NDCM": dimethyl 2,6-naphthalene dicarboxylate (a1-1)
"TMAn": trimellitic anhydride (a1-2)
"AdA": Adipic acid "SebA": Sebacic acid "GI-1000": Hydrogenated polybutadiene diol (a2-1) (GI-1000 manufactured by Nippon Soda Co., Ltd., Mn1630)
"GI-2000": Hydrogenated polybutadiene diol (a2-1) (GI-2000 manufactured by Nippon Soda Co., Ltd., Mn2300)
"GI-3000": Hydrogenated polybutadiene diol (a2-1) (GI-3000 manufactured by Nippon Soda Co., Ltd., Mn3870)
"P2033": Hydrogenated dimer diol (P2033 manufactured by Croda, molecular weight 538)
"EG": Ethylene glycol "NPG": Neopentyl glycol "TMP": Trimethylolpropane

The resin composition (structural sites derived from the components) of the obtained polyester resin is shown in Table 1 below.

In addition, the glass transition temperature (℃), acid value (mgKOH/g), peak top molecular weight (Mp), weight average molecular weight (Mw), dielectric properties (permittivity Dk, dielectric loss tangent Df), probe tack ( N), ester bond concentration (mmol/g), aromatic polycarboxylic acid (a1-1) content (mol%), and polydiene compound (a2-1) content (wt%) in this specification. Measurements were performed as described. Various physical properties of the polyester resin are shown in Table 2 below.
Note that probe tack was not evaluated for Comparative Examples 2 to 4 because the dielectric properties were poor and the problems of the present application could not be solved.

<Curing agent (B)>
The following were prepared as the curing agent (B).
(B-1): Tetraglycidyldiaminodiphenylmethane (“jER604” manufactured by Mitsubishi Chemical Corporation)

An adhesive composition was produced as described below using the polyester resin (A) and curing agent (B) obtained above.

<Example 5>
The polyester resin (A-1) obtained above was diluted with toluene to a solid content concentration of 50%, and the curing agent (B- An adhesive composition was obtained by blending 2.5 parts of 1) (solid content), diluting with toluene so that the total solid content was 50%, stirring, and mixing.

<Examples 6 to 12, Comparative Examples 5 and 6>
An adhesive composition was obtained in the same manner as in Example 5, except that each component was blended as shown in Table 3 below.
The obtained adhesive composition was evaluated as follows. The evaluation results are shown in Table 3 below.

[Adhesive strength (peel strength) (PI/adhesive layer/Cu)]
The adhesive composition prepared above was applied with an applicator to a polyimide film "Kapton 200H" (manufactured by DuPont-Toray) with a thickness of 50 μm, 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 with a thickness of 30 μm was laminated with the adhesive layer surface of the polyimide film with an adhesive layer (lamination conditions: 170°C, 0.2 MPa, feeding speed 1.5 m/min), and then heat treated in an oven at 160°C for 4 hours. A laminate was obtained by curing.
A test piece was prepared by cutting the laminate obtained above into a 1 cm wide piece. 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 (peel rate: 50 mm/min, peeling angle: 180°).

[Gel fraction]
The adhesive composition prepared above was applied to a release-treated polyethylene terephthalate (PET) film (thickness: 38 μm), and then dried at 120° C. for 5 minutes to form an adhesive layer with a dry film thickness of 50 μm. Thereafter, a release-treated PET film was attached to the adhesive layer to protect its surface, and then heat treated and cured in an oven at 160° C. for 4 hours to obtain an adhesive sheet.
The adhesive sheet obtained above was cut into a size of 4 cm x 4 cm. After peeling off the release film on one side, it was wrapped in a 200 mesh SUS wire mesh and immersed in toluene at 23°C for 24 hours to determine the weight of the undissolved adhesive component remaining in the wire mesh relative to the weight of the adhesive before dipping. The percentage was defined as the gel fraction.

[Dielectric properties of adhesive layer]
The dielectric properties (dielectric constant Dk, dielectric loss tangent Df) of the adhesive layer of the adhesive sheet obtained above were measured by a cavity resonator perturbation method using a network analyzer.

[Probe tack]
The adhesive composition prepared above was applied onto a 38 μm thick PET film (“Lumirror T60” manufactured by Toray Industries, Inc.) using an applicator and dried at 120°C for 5 minutes, resulting in a sheet with a dry film thickness of the adhesive composition of 25 μm. was created. Thereafter, a release-treated PET film was attached to the adhesive layer to protect its surface, and then heat treated and cured in an oven at 160° C. for 4 hours to obtain an adhesive sheet.
After cutting the adhesive sheet obtained above into a size of 12 mm x 12 mm, the release-treated PET film was peeled off, and a probe tack tester (manufactured by Tester Sangyo Co., Ltd., TE -6001) with a probe diameter of 5 mmΦ, pushing speed of 10 mm/sec, pulling speed of 10 mm/sec, pressurization time of 5 seconds, and application pressure of 1000 gf/cm ² .

From the results in the table above, the adhesive compositions of Examples 5 to 12 using the polyester resins (A-1) to (A-4) of Examples 1 to 4 have dielectric properties and adhesive properties (probe tack). It was an excellent adhesive composition.
On the other hand, the adhesive compositions of Comparative Examples 5 and 6 using the polyester resin (A'-1) of Comparative Example 1 had poor adhesive properties. Furthermore, the polyester resins (A'-2) to (A'-4) of Comparative Examples 2 to 4 were inferior in dielectric loss tangent.

The adhesive composition of the present invention is an adhesive composition containing a polyester resin (A), and has an extremely low dielectric constant and a low dielectric loss tangent, and also has excellent adhesive properties. Therefore, it is effective as an adhesive for producing a laminate of metal and plastic, for example, an adhesive used for flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards.

Claims (12)

An adhesive composition containing a polyester resin (A) having a structural part derived from a polyhydric carboxylic acid (a1) and a structural part derived from a polyhydric alcohol (a2),
The content of structural moieties derived from aromatic polyvalent carboxylic acids (a1-1) is 20 mol% or more of the total structural moieties derived from polyvalent carboxylic acids (a1),
An adhesive composition characterized in that the content of structural moieties derived from polydiene diols and/or hydrogenated polydiene diols (a2-1) is 50% by weight or more based on the entire polyester resin (A). The adhesive composition according to claim 1, wherein the polyester resin (A) has a dielectric loss tangent of 0.01 or less at a temperature of 23° C., a relative humidity of 50% RH, and a frequency of 10 GHz. The adhesive composition according to claim 1 or 2, wherein the polyester resin (A) has a glass transition temperature of -60 to 60°C. The adhesive composition according to claim 1 or 2, wherein the polyester resin (A) has an acid value of 3 mgKOH/g or more. The adhesive composition containing a polyester resin according to claim 1 or 2, wherein at least one of the polyhydric carboxylic acids and the polyhydric alcohol contains a condensed polycyclic aromatic compound. Containing the polyester resin according to claim 1 or 2, wherein the polyvalent carboxylic acids include trivalent or higher polyvalent carboxylic acids (a2-1) having an acid anhydride group of 0 or 1. Adhesive composition. The adhesive composition according to claim 1 or 2, wherein the polyester resin (A) is amorphous. The adhesive composition according to claim 1 or 2, further comprising a curing agent (B). 9. The adhesive composition according to claim 8, wherein the content of the curing agent (B) is 30 parts by weight or less based on 100 parts by weight of the polyester resin. An adhesive obtained by curing the adhesive composition according to claim 1 or 2. The adhesive according to claim 10, which is used for bonding electronic material members. 12. The adhesive according to claim 11, wherein the electronic material member is at least one selected from a flexible copper-clad laminate, a coverlay, and a bonding sheet.