Adhesive composition and adhesive

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

[Technical Field]

[0001] 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 dissipation factor and excellent adhesion, and an adhesive obtained by curing this adhesive composition. [Background technology]

[0002] Polyester resins have been used in a wide range of applications, such as films, PET bottles, fibers, toners, electrical components, adhesives, and pressure-sensitive adhesives, due to their excellent heat resistance, chemical resistance, durability, and mechanical strength. In addition, polyester resins are highly polar due to their polymer structure, and are known to exhibit excellent adhesion to polar polymers such as polyester, polyvinyl chloride, polyimide, and epoxy resin, as well as to metal materials such as copper and aluminum. Taking advantage of these properties, its use as an adhesive for producing laminates of metal and plastic, such as flexible copper-clad laminates and flexible printed circuit boards (hereinafter, both of which may be collectively referred to as FPCs), is being considered.

[0003] Flexible copper clad laminates and flexible printed circuit boards are a type of printed circuit board made by laminating thin copper foil and an insulating film (plastic film). FPCs are flexible and can be deformed repeatedly, and they can maintain their performance as printed circuit boards even after deformation. FPCs are thin and suitable for use in foldable or moving parts, and demand for them is increasing in recent years as electronic devices such as smartphones, televisions, and laptops become ever smaller, lighter, and thinner. Furthermore, in line with the recent trend toward higher speeds and higher frequencies of transmission signals, there is a growing demand for low dielectric properties such as low dielectric constant and low dielectric loss tangent.

[0004] For example, Patent Document 1 discloses that a polyester resin containing specific amounts of a structural moiety having a polycyclic structure and a structural moiety having 10 or more continuous carbon chains has excellent solvent solubility, heat resistance, and adhesive strength, and has excellent dielectric properties such as a low relative dielectric constant and dielectric loss tangent. Furthermore, Patent Document 2 discloses that a polyester having an ester group concentration of 5000 eq / 106 g or less and a glass transition temperature of −30° C. or more has excellent solvent solubility, heat resistance, and adhesive strength, and has low relative dielectric constant and dielectric loss tangent, resulting in excellent dielectric properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 200715 [Patent Document 2] International Publication No. 2021 / 200716 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in recent years, in the field of electronic materials such as flexible copper-clad laminates and flexible printed circuit boards, adhesive layers used therein are required to have even lower dielectric properties, such as lower dielectric constants and lower dielectric loss tangents.

[0007] In the technologies disclosed in the above Patent Documents 1 and 2, the polar group concentration is reduced by using a monomer having a continuous carbon chain of 10 or more, thereby lowering the dielectric constant and dielectric loss tangent. However, further reduction of the polar group concentration in order to further reduce the dielectric tends to significantly impair adhesiveness, making it difficult to achieve both the high level of low dielectric properties and adhesiveness that has been required in recent years.

[0008] Under these circumstances, an object of the present invention is to provide an adhesive composition that has an even lower dielectric constant and dielectric dissipation factor and also has excellent adhesion after curing, and an adhesive obtained by curing this adhesive composition. [Means for solving the problem]

[0009] However, in view of the above circumstances, the present inventors have conducted extensive research and have found that the adhesive composition described below meets the object of the present invention, thereby completing the present invention. That is, the gist of the present invention is an adhesive composition containing a polyester resin (A) having a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), the content of structural moieties derived from aromatic polycarboxylic acids (a1-1) is 20 mol % or more of the total structural moieties derived from polycarboxylic acids (a1); The adhesive composition has a content of structural moieties derived from polydiene diols and / or hydrogenated polydiene diols (a2-1) of 50% by weight or more of the total polyester resin (A).

[0010] That is, the present invention has the following aspects [1] to

[12] . [1] An adhesive composition containing a polyester resin (A) having a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), the content of structural moieties derived from aromatic polycarboxylic acids (a1-1) is 20 mol % or more of the total structural moieties derived from polycarboxylic 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 of the total polyester resin (A). [2] The adhesive composition according to [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 the above [1] or [2], wherein the glass transition temperature of the polyester resin (A) is -60 to 60°C. [4] The polyester resin (A) has an acid value of 3 mgKOH / g or more. The adhesive composition according to any one of the above items [1] to [3]. [5] An adhesive composition containing the polyester resin according to any one of [1] to [4] above, wherein at least one of the polycarboxylic acids and the polyhydric alcohols contains a condensed polycyclic aromatic compound. [6] An adhesive composition containing a polyester-based resin according to any one of [1] to [5] above, characterized in that the polyvalent carboxylic acids include trivalent or higher polyvalent carboxylic acids (a2-1) having 0 or 1 acid anhydride group. [7] The adhesive composition according to any one of the above [1] to [6], wherein the polyester resin (A) is non-crystalline. [8] 3. The adhesive composition according to claim 1, 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] 3. An adhesive obtained by curing the adhesive composition according to claim 1 or 2.

[11] 11. The adhesive according to claim 10, which is used for bonding electronic materials.

[12] 12. The adhesive according to claim 11, wherein the electronic material is at least one selected from the group consisting of a flexible copper-clad laminate, a coverlay, and a bonding sheet.

[0011] As in Patent Documents 1 and 2, a common approach to lowering the dielectric constant and dielectric loss tangent is to use a large amount of polycarboxylic acids or polyhydric alcohols having long-chain alkyl groups and reduce the ester bond concentration, but this results in a decrease in adhesive strength. Furthermore, it is difficult to achieve even lower dielectric properties by lowering the ester bond concentration. The present inventors have discovered the unique effect of improving low dielectric properties and also improving adhesiveness by incorporating a specific amount or more of a polybutadiene-derived structural moiety into a polyester resin, and have completed the present invention. [Effects of the Invention]

[0012] The adhesive composition containing the polyester-based resin used in the present invention has a low dielectric constant and a low dielectric loss tangent, and forms an adhesive composition with excellent adhesion. In particular, such an adhesive composition is effective as an adhesive for producing laminates of metal and plastic, for example, for bonding electronic materials, and particularly as an adhesive used in producing flexible printed wiring boards such as flexible copper-clad laminates, coverlays, and bonding sheets.

[0013] The polyester resin used in the present invention can obtain the effects of the present invention because it contains at least specific amounts of structural moieties derived from polydiene diols and / or hydrogenated polydiene diols and structural moieties derived from aromatic polycarboxylic acids. DETAILED DESCRIPTION OF THE INVENTION

[0014] The configuration of the present invention will be described in detail below, but these are merely examples of preferred embodiments. In the present invention, the term "class" added after the name of a compound is a concept that encompasses 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 acid esters. In the present invention, "x and / or y (x and y are any constitutions or components)" means three combinations: x only, y only, and x and y.

[0015] The adhesive composition of the present invention contains at least a polyester resin containing a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin will be described.

[0016] <Polyester resin (A)> The polyester resin (A) used in the present invention contains a structural unit derived from a polycarboxylic acid (a1) and a structural unit derived from a polyhydric alcohol (a2) in the molecule, and the content of the structural moiety derived from an aromatic polycarboxylic acid (a1-1) is 20 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1), The content of structural moieties derived from polydiene diols and / or hydrogenated polydiene diols (a2-1) (hereinafter, polydiene diols and / or hydrogenated polydiene diols (a2-1) may be referred to as polydiene diols (a2-1)) is 50% by weight or more of the total polyester resin (A).

[0017] [Polycarboxylic acids (a1)] Examples of polycarboxylic acids in the structural moiety derived from polycarboxylic acids (a1) include aromatic polycarboxylic acids (a1-1) described below; trivalent or higher polycarboxylic acids (a1-2) having 0 or 1 acid anhydride group described below; alicyclic polycarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their acid anhydrides; and aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, etc. One or more types of polycarboxylic acids can be used.

[0018] Examples of the aromatic polycarboxylic acids (a1-1) include monocyclic aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl isophthalate, and orthophthalic acid; polycyclic aromatic polycarboxylic acids such as biphenyldicarboxylic acid, naphthalenedicarboxylic acid, and dimethyl naphthalenedicarboxylate; and among the polycyclic aromatic polycarboxylic acids, condensed polycyclic aromatic polycarboxylic acids such as naphthalenedicarboxylic acid and dimethyl naphthalenedicarboxylate, and derivatives thereof (aromatic dicarboxylic acids). Other examples include aromatic oxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Furthermore, trifunctional or higher aromatic carboxylic acids introduced into polyester resins to impart a branched skeleton or acid value are also included in the aromatic polycarboxylic acids. Examples of tri- or higher functional aromatic polycarboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride. Among these, from the viewpoint of dielectric properties, polycyclic aromatic polycarboxylic acids are preferred, among which condensed polycyclic aromatic polycarboxylic acids are particularly preferred, and among the condensed polycyclic aromatic polycarboxylic acids, dimethyl naphthalenedicarboxylate is particularly preferred. Among the monocyclic aromatic polycarboxylic acids, terephthalic acid, dimethyl terephthalate, isophthalic acid, and dimethyl isophthalate are preferred. In order to lower the crystallinity and ensure stability after dissolution in a solvent, it is preferable to use a plurality of polycarboxylic acids.

[0019] The content of structural units derived from aromatic polycarboxylic acids (a1-1) relative to the total polycarboxylic acids (a1) is 20 mol% or more, preferably 40 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 100 mol%. When the content of aromatic polycarboxylic acids is within the above range, excellent dielectric properties can be achieved, and adhesive properties can also be achieved. Conversely, if the content is too low, the long-term durability in a humid and hot environment tends to be insufficient, and the dielectric loss tangent tends to be inferior.

[0020] The content (mol %) of aromatic polycarboxylic acids relative to the total polycarboxylic acids can be calculated from the following formula. Aromatic polycarboxylic acid content (mol%)=(aromatic polycarboxylic acid (mol) / polycarboxylic acid (mol))×100

[0021] Furthermore, the content of the structural moiety derived from aromatic polycarboxylic acids (a1-1) relative to the total weight of the polyester resin is preferably 1 to 50 wt%, more preferably 3 to 40 wt%, even more preferably 5 to 30 wt%, and particularly preferably 10 to 25 wt%. When the content of aromatic polycarboxylic acids is within the above range, excellent dielectric properties can be achieved while also achieving good adhesive properties. Conversely, if the content is too low, the initial adhesiveness tends to be insufficient or the tackiness tends to be excessively strong, while if the content is too high, the initial adhesiveness tends to be insufficient.

[0022] When imparting an acid value to the polyester resin (A), it is preferable from the viewpoint of adhesive strength that the structural moiety derived from the polycarboxylic acid (a1) contains a structural moiety derived from a trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group. The valence of the carboxy group in the structural moiety derived from the trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group is preferably 3 to 6, more preferably 3 to 4. Examples of the trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group and constituting the structural moiety derived from the trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group include, for example, the above-mentioned trivalent or higher aromatic polycarboxylic acids having 0 or 1 acid anhydride group. Examples include trimellitic anhydride, trimellitic acids, and trimesic acids. Examples of the trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group other than the above include hydrogenated trimellitic anhydride. Among these, those having one acid anhydride group are preferred, and a structural moiety derived from trimellitic anhydride is particularly preferred.

[0023] 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.

[0024] 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, and dodecanedioic acid.

[0025] When the polyester resin (A) contains the structural moieties derived from the alicyclic polycarboxylic acids and the structural moieties derived from the aliphatic polycarboxylic acids, the total content of the structural moieties derived from the alicyclic polycarboxylic acids and the structural moieties derived from the aliphatic polycarboxylic acids in the structural moieties derived from the polycarboxylic acids (a1) is preferably 30 mol % or less, more preferably 20 mol % or less, and particularly preferably 10 mol % or less.

[0026] The polyester resin (A) may contain structural units derived from aromatic dicarboxylic acids having sulfonic acid groups, such as structural units derived from sulfoterephthalic acid, structural units derived from 5-sulfoisophthalic acids, structural units derived from 4-sulfophthalic acids, structural units derived from 4-sulfonaphthalene-2,7-dicarboxylic acids, and structural units derived from 5(4-sulfophenoxy)isophthalic acids, as well as structural units derived from aromatic dicarboxylic acid salts having sulfonate groups, such as their metal salts and ammonium salts. However, in terms of the hygroscopicity of the polyester resin (A) and the compatibility of the resin, the content of structural units derived from polyvalent carboxylic acids (a1) relative to the total amount of structural units 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 %.

[0027] [Structural moiety derived from polyhydric alcohols (a2)] In the present invention, the structural moiety derived from the polyhydric alcohol (a2) contains a structural unit derived from the polydiene diol (a2-1). The polydiene diols (a2-1) constituting the structural moiety derived from the polydiene diols (a2-1) are preferably polydiene diols formed from conjugated dienes having 4 to 9 carbon atoms and / or hydrogenated polydiene diols formed from conjugated dienes having 4 to 9 carbon atoms, in terms of excellent dielectric properties. Examples include polybutadiene diols, polyisoprene diols, polyhexadiene diols, etc., both of which have hydroxyl groups at their ends, and hydrogenated products thereof. These may be used alone or in combination of two or more. Among these, hydrogenated polybutadiene diols are preferred in terms of suppressing gelation during the production of the polyester resin (A).

[0028] The hydroxyl groups at both ends may be bonded directly to the polydiene structure or via a bond chain. Examples of such linking chains include 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-, and -CO(CH2)mCO- (m=1 to 10). Among these, alkylene chains are preferred in that they do not impair the effects of the present invention. The above linking chains may be contained alone or in combination of two or more types.

[0029] The number average molecular weight of the polydiene diol (a2-1) is preferably 500 to 10,000, more preferably 600 to 5,000, even more preferably 700 to 2,800, and particularly preferably 800 to 1,800, from the viewpoint of excellent dielectric properties and compatibility with polyester.

[0030] When the polydiene diol (a2-1) is a hydrogenated polydiene diol, the hydrogenation ratio is not particularly limited, but is preferably 80% or more, and particularly preferably 90% or more. If the hydrogenation ratio is low, the appearance of the polyester resin (A) may deteriorate due to the influence of remaining unsaturated groups, and gelation may easily occur during the production of the polyester resin (A), making production difficult. The upper limit is usually 100%.

[0031] The polydiene diols preferably have side chains, and the proportion of side chains in the entire polydiene diols (a2-1) is preferably 10% or more, more preferably 20% or more, even more preferably 30% or more, and most preferably 40% or more. The ratio of the side chains to the total can be calculated by the following formula 1. [Formula 1] Percentage of side chains to the total (%) = number of carbon atoms in side chains / total number of carbon atoms x 100

[0032] In the polyester resin (A) used in the present invention, from the viewpoint of dielectric properties and adhesiveness, the content of structural moieties derived from polydiene diols (a2-1) in the structural moieties derived from polyhydric alcohols (a2) is preferably 10 mol% or more, more preferably 15 to 90 mol%, even more preferably 20 to 80 mol%, and particularly preferably 25 to 70 mol%. When the content of structural moieties derived from polydiene diols (a2-1) is within the above range, low moisture absorption, dielectric properties, and adhesiveness are excellent. If the content is too high, adhesiveness tends to be poor or tackiness tends to be excessively strong. Conversely, if the content is too low, low moisture absorption, dielectric properties, and adhesiveness tend to be poor.

[0033] Furthermore, the content of the structural moiety derived from polydiene diols and / or hydrogenated polydiene diols (a2-1) relative to the total weight of the polyester resin (A) is 50% by weight or more, preferably 55 to 95% by weight, more preferably 60 to 90% by weight, and even more preferably 65 to 85% by weight. When the content of the structural moiety derived from polydiene diols (a2-1) is within the above range, low moisture absorption, dielectric properties, and adhesiveness are excellent. If the content is too high, the adhesiveness tends to be poor and the tackiness tends to be excessively strong, while if the content is too low, the low moisture absorption, dielectric properties, and adhesiveness tend to be poor.

[0034] Examples of structural moieties other than polydiene diols and / or hydrogenated polydiene diols (a2-1) include structural moieties derived from dimer diols, structural moieties derived from bisphenol skeleton-containing monomers, structural moieties derived from aliphatic polyhydric alcohols (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. The structural moieties derived from polyhydric alcohols (a2) may be contained alone or in combination of two or more.

[0035] Furthermore, in the present invention, from the viewpoint of a low dielectric loss tangent, the total of the structural moieties derived from the aromatic polycarboxylic acids (a1-1) and the structural moieties derived from the polydiene diols (a2-1) is preferably 90% by weight or more of the polyester resin (A), more preferably 95% by weight or more.

[0036] The total of the structural moieties derived from the aromatic polycarboxylic acids (a1-1) and the structural moieties derived from the polydiene diols (a1-2) can be calculated by the following formula 2. [Formula 2] Total (wt%) of structural moieties derived from polycarboxylic acids (a1-1) and polydiene diols (a2-1)=[weight of structural moieties (a1-1) derived from aromatic polycarboxylic acids+weight of polydiene diols (a2-1)] / weight of total polyester×100

[0037] Examples of dimer diols constituting the structural moiety derived from dimer diols include diols derived from dimer acids of unsaturated fatty acid dimers having an average carbon number of 10 to 26 (preferably 12 to 24, more preferably 14 to 22).Specific examples include diols derived from unsaturated fatty acids such as oleic acids, linoleic acids, linolenic acids, and erucic acids.

[0038] Examples of the bisphenol skeleton-containing monomer constituting the structural moiety 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, bisphenol Z, 4,4'-dihydroxybenzophenone, bisphenolfluorene, and the like, 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 groups of bisphenols.

[0039] Examples of the aliphatic polyhydric alcohol constituting the structural moiety derived from the aliphatic polyhydric alcohol include aliphatic diols such as ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 1,10-decanediol, 2-ethyl-2-butylpropanediol, 2,4-diethyl-1,5-pentanediol, and 2,2,4-trimethyl-1,3-pentanediol, and trivalent or higher aliphatic polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. Among these, ethylene glycol and trimethylolpropane are preferred.

[0040] Examples of the alicyclic polyhydric alcohol constituting the structural moiety derived from the alicyclic polyhydric alcohol include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.

[0041] The aromatic polyhydric alcohol constituting the structural moiety derived from the aromatic polyhydric alcohol is one other than the bisphenol skeleton-containing monomer, and examples thereof include paraxylene glycol, metaxylene glycol, orthoxylene glycol, 1,4-phenylene glycol, and ethylene oxide adducts of 1,4-phenylene glycol.

[0042] Furthermore, the aromatic polyhydric alcohol also includes a fluorene-based diol represented by the following general formula (1).

[0043] [ka] 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, etc. R2, R3, R4, and R5 are each 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 from one another.

[0044] When the polyester resin (A) contains a structural moiety derived from a dimer diol, a structural moiety derived from a bisphenol skeleton-containing monomer, a structural moiety derived from an aliphatic polyhydric alcohol, a structural moiety derived from an alicyclic polyhydric alcohol, or a structural moiety derived from an aromatic polyhydric alcohol, the total content of the structural moieties derived from dimer diols, the structural moieties derived from a bisphenol skeleton-containing monomer, the structural moiety derived from an aliphatic polyhydric alcohol, the structural moiety derived from an alicyclic polyhydric alcohol, and the structural moiety derived from an aromatic polyhydric alcohol in the structural moieties derived from the polyhydric alcohols (a2) is preferably 90 mol% or less, more preferably 80 mol% or less, and particularly preferably 75 mol% or less.

[0045] Furthermore, when the polyester resin (A) contains a structural portion derived from an aliphatic polyhydric alcohol, the content of the structural portion derived from an aliphatic polyhydric alcohol in the structural portion derived from the polyhydric alcohols (a2) is preferably 90 mol% or less, more preferably 80 mol% or less, and particularly preferably 75 mol% or less.

[0046] The polyester resin (A) used in the present invention may have at least one structural moiety selected from the group consisting of a structural moiety derived from a trivalent or higher aromatic polycarboxylic acid and a structural moiety derived from a trivalent or higher aliphatic polyalcohol for the purpose of introducing a branched skeleton. That is, the polyester resin (A) may contain at least one selected from the group consisting of the trivalent or higher aromatic polycarboxylic acid and the trivalent or higher aliphatic polyalcohol as a copolymerization component. In particular, when crosslinking is formed by reacting with the curing agent (B) described below, the introduction of a branched skeleton increases the number of reactive sites in the resin, resulting in a strong adhesive layer with high crosslink density. Among these, trimethylolpropane is preferred for its versatility. When a trivalent or higher polycarboxylic acid (a1-2) having zero or one acid anhydride group is used in the depolymerization reaction described below, a trivalent or higher aromatic polycarboxylic acid may be used in addition to the polycarboxylic acid used in the depolymerization reaction.

[0047] When at least one selected from the group consisting of trivalent or higher aromatic polycarboxylic acids and trivalent or higher aliphatic polyhydric alcohols is used for the purpose of introducing a branched skeleton into the polyester resin (A), the content of the trivalent or higher aromatic polycarboxylic acids relative to the total polycarboxylic acids (a1) or the content of the trivalent or higher polyhydric alcohol relative to the total polyhydric alcohols (a2) (excluding trivalent or higher polycarboxylic acids (a1-2) having 0 or 1 acid anhydride group used in the depolymerization reaction) is preferably 0.1 to 5 mol %, more preferably 0.3 to 3 mol %, and even more preferably 0.5 to 2 mol %. If the content of either or both is too high, the mechanical properties such as elongation at break of the coating film formed by application of the adhesive tend to decrease, resulting in a decrease in adhesive strength, and gelation may also occur during polymerization.

[0048] Furthermore, the polyester resin (A) used in the present invention may contain a structural moiety derived from an oxycarboxylic acid compound. The oxycarboxylic acid compound is a compound having a hydroxyl group and a carboxyl group in its molecular structure. Examples of the oxycarboxylic acid compound constituting the structural moiety derived from the oxycarboxylic acid compound include 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, 4,4-bis(p-hydroxyphenyl)valeric acid, etc. These may be used alone or in combination of two or more.

[0049] [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., even more 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 adhesiveness and dielectric properties tend to be poor and the tackiness tends to be excessively strong, while if the glass transition temperature (Tg) is too high, the adhesiveness tends to be insufficient.

[0050] The glass transition temperature (Tg) was measured as follows. The glass transition temperature (Tg) can be determined by measurement using a differential scanning calorimeter, where the measurement conditions are a temperature range of −90 to 100° C. and a temperature rise rate of 10° C. / min.

[0051] [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, and even more preferably 7 to 20 mgKOH / g. When the acid value is within the above range, the degree of crosslinking when cured with a curing agent (B) such as an epoxy (described below) is appropriate, resulting in an excellent balance of adhesion, heat resistance, low moisture absorption, long-term durability in a humid and hot environment, and low dielectric properties. If the acid value is too low, when a curing agent (B) such as a polyepoxy compound is contained in the adhesive composition, the number of crosslinking points with the curing agent (B) is insufficient, resulting in a low degree of crosslinking and insufficient heat resistance. On the other hand, if the acid value is too high, the low moisture absorption and long-term durability in a humid and hot environment will be reduced, and a large amount of curing agent (B) will be required during curing, making it difficult to achieve the low dielectric properties that have become increasingly popular in recent years.

[0052] The definition and measurement method of the acid value are as follows. The acid value (mgKOH / g) can be 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 according to JIS K 0070. In the present invention, the acid value of the polyester resin (A) is determined based on the amount of carboxyl groups in the resin. This is due to the content of silyl groups.

[0053] [Hydroxyl value of polyester resin (A)] 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, and 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.

[0054] The hydroxyl value of the polyester resin (A) was determined by neutralization titration according to JIS K 0070. This is what is required.

[0055] 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, and even more preferably 1.5 to 3.0 mmol / g. If the ester group concentration is too low, the polarity and elastic modulus of the polyester resin (A) decrease, which tends to result in poor adhesion or excessive tackiness, while if the ester group concentration is too high, it tends to adversely affect the dielectric properties.

[0056] The ester group concentration (mmol / g) refers to the number of moles of ester groups per gram of polyester resin (A), and can be calculated, for example, from the amounts charged. The calculation method is to divide the number of moles of the polycarboxylic acid (a1) or the polyhydric alcohol (a2), whichever is charged less frequently, by the total weight of the final product, and an example of the calculation formula is shown below. When the polycarboxylic acids (a1) and the polyhydric alcohols (a2) are charged in equal molar amounts, either of the following calculation formulas may be used. Furthermore, when a monomer having both a carboxylic acid and a hydroxyl group is used, or when polyester is prepared from caprolactone or the like, the calculation method will be changed appropriately.

[0057] <When the amount of polycarboxylic acids (a1) is small> Ester group concentration (mmol / g) = [(A1 / α1 × m1 + A2 / α2 × m2 + A3 / α3 × m3 ) / Z] × 1000 A: Amount of polycarboxylic acid (a1) (g) α: Molecular weight of polycarboxylic acid (a1) m: number of carboxyl groups per molecule of polycarboxylic acid (a1) Z: Finished weight (g)

[0058] <When the amount of polyhydric alcohol (a2) is small> Ester group concentration (mmol / g) = [(B1 / β1 × n1 + B2 / β2 × n2 + B3 / β3 × n3 ) / Z] × 1000 B: Amount of polyhydric alcohol (a2) (g) β: Molecular weight of polyhydric alcohols (a2) n: number of hydroxyl groups per molecule of polyhydric alcohols (a2) Z: Finished weight (g)

[0059] The ester group concentration can also be measured by a known method using NMR, etc. For example, the ester group concentration, composition, and composition ratio of the polyester resin (A) can be determined by H-NMR measurement (proton-type nuclear magnetic resonance spectroscopy) or C-NMR measurement (carbon-type nuclear magnetic resonance spectroscopy) at a resonance frequency of 400 MHz.

[0060] Furthermore, the concentration of polar groups other than the ester groups and reactive functional groups contained in the polyester resin (A) is preferably low from the viewpoint of low moisture absorption and long-term durability in a humid and hot environment. Other examples of the polar group include an amide group, an imide group, a urethane group, a urea group, an ether group, and a carbonate group.

[0061] 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, particularly preferably 1 mmol / g or less, even more preferably 0.5 mmol / g or less, and most preferably 0.2 mmol / g or less.

[0062] 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 in terms of low moisture absorption and long-term durability in a humid and hot 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, even more preferably 1 mmol / g or less, and most preferably 0.5 mmol / g or less. 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, and even more preferably 2.5 mmol / g or less.

[0063] The carbonate group concentration of the polyester resin (A) is 3 mmol / g or less. It is preferable that the concentration is 2 mmol / g or less, more preferably 2 mmol / g or less, and particularly preferably 1 mmol / g or less. It is preferably 0.2 mmol / g or less, more preferably 0.5 mmol / g or less, and most preferably 0.2 mmol / g or less. g or less.

[0064] [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, further preferably 30,000 to 250,000, and particularly preferably 50,000 to 200,000. If the weight-average molecular weight (Mw) is too low, the low moisture absorption, long-term durability in a humid and hot environment, and low dielectric properties tend to be insufficient, while if the weight-average molecular weight (Mw) is too high, the adhesive strength tends to be insufficient and the solution viscosity during application tends to be too high, making it difficult to obtain a uniform coating film.

[0065] 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, and even more preferably 20,000 to 80,000. If the peak top molecular weight (Mp) is too low, the low moisture absorption, long-term durability in a humid and hot environment, and low dielectric properties tend to be insufficient, whereas if the peak top molecular weight (Mp) is too high, the adhesive strength tends to be insufficient and the solution viscosity during application tends to be too high, making it difficult to obtain a uniform coating film.

[0066] The weight average molecular weight (Mw) and peak top molecular weight (Mp) were measured by the following methods. The weight-average molecular weight (Mw) and peak-top molecular weight (Mp) can be determined by measuring three columns in series: 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 / column, packing material: styrene-divinylbenzene copolymer, packing particle size: 10 μm) in a high-performance liquid chromatograph (Waters Japan, "Waters 2695 (main body)" and "Waters 2414 (detector)"), and converting the values ​​into standard polystyrene molecular weights.

[0067] [Water absorption rate (wt%) of polyester resin (A)] The water absorption of the polyester resin (A) used in the present invention is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, and even more preferably 0.6% by weight or less, with the lower limit usually being 0% by weight. If the water absorption rate is too high, the durability against humidity and heat and the insulating reliability tend to decrease, and the dielectric properties tend to be poor.

[0068] The water absorption rate was measured as follows. A polyester resin (A) solution (not including the curing agent (B) described below) was applied to a release film with an applicator and dried at 120°C for 10 minutes to produce a sheet with a dry polyester resin (A) layer thickness of 65 μm. This sheet was cut into a size of 7.5 cm x 11 cm, and the polyester resin (A) layer side of the sheet was laminated onto a glass plate whose weight had been measured in advance. The release film was then peeled off. Six of these polyester resin (A) layers were stacked to obtain a test plate with a polyester resin layer thickness of 390 μm on the glass plate, and its weight was measured. The test plate thus obtained is immersed in purified water at 23°C for 24 hours, then removed, the surface water is wiped off, the weight is measured, and the plate is then dried at 70°C for 2 hours, and the weight of the dried test plate is measured. From the weights measured in each of these steps, the water absorption rate (wt%) is calculated according to the following formula 3. [Formula 3] Water absorption rate (weight%)=(cd) / (ba)×100 a: Weight of the glass plate alone b: Initial weight of test plate c: Weight of the test plate immediately after removing it from the purified water and wiping off the water d: Weight of test plate after drying at 70°C for 2 hours

[0069] [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 under an environment of 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, and even 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.

[0070] (Dielectric loss tangent (Df)) The polyester resin (A) used in the present invention preferably has a dielectric loss tangent at a frequency of 10 GHz under an environment of a temperature of 23°C and a relative humidity of 50%RH of 0.01 or less, more preferably 0.005 or less, even more preferably 0.003 or less, particularly preferably 0.0025 or less, even more preferably 0.002 or less, especially 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.

[0071] The 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 highly adhesive and it is difficult to prepare a measurement sample for the polyester resin (A) alone, the polyester resin (A) can be measured sandwiched between films, and the dielectric properties of the polyester resin (A) alone can be calculated by subtracting the film content.

[0072] [Probe Tack (N) of Polyester Resin (A)] The probe tack of the polyester resin (A) used in the present invention is preferably 5 N or less, more preferably 3 N or less, particularly preferably 2 N or less, and even more preferably 1.5 N or less. The lower limit is usually 0 N. If the probe tack is too high, the adhesiveness will be strong, which will tend to result in poor handling and reworkability when used as an adhesive sheet, and problems will tend to occur in the processing of flexible printed wiring boards.

[0073] The method for measuring the probe tack is as follows. A polyester resin (A) solution (not including the curing agent (B) described below) was applied to a 38 μm-thick PET film (Toray Industries, Inc., "Lumirror T60") using an applicator and dried at 120°C for 5 minutes to produce a sheet with a dry thickness of 25 μm for the polyester resin (A) layer. The sheet was then cut into 12 mm x 12 mm pieces and measured under an environment of 23°C and 50% RH using a probe tack tester (Tester Sangyo Co., Ltd., TE-6001) with a probe diameter of 5 mm, a push-in speed of 10 mm / sec, a pull-up speed of 10 mm / sec, a pressure time of 5 seconds, and an application pressure of 1000 gf / cm. 2 It can be determined by measuring

[0074] In the present invention, it is preferable that the polyester resin (A) is a non-crystalline polyester resin in terms of solvent solubility and solution stability. If the compound is crystalline, the solvent solubility and solution stability thereof tend to be insufficient. The term "non-crystalline" can be confirmed by a differential scanning calorimeter, and refers to a state in which no endothermic peak due to crystalline melting is observed when measured, for example, at a temperature range of -90 to 400°C and a temperature rise rate of 10°C / min. The temperature range and temperature rise rate can be appropriately changed depending on the sample.

[0075] [Production of polyester resin (A)] The polyester resin (A) of the present invention can be produced by polycondensation reaction of the above-mentioned polycarboxylic acids (a1) and the above-mentioned polyhydric alcohols (a2) in the presence of a catalyst using a known method. That is, since the polyester resin (A) is obtained by polycondensation reaction of the polycarboxylic acids (a1) and the polyhydric alcohols (a2), it has structural moieties derived from the polycarboxylic acids (a1) and the polyhydric alcohols (a2). In the polycondensation reaction, an esterification reaction or a transesterification reaction is first carried out, followed by the polycondensation reaction. When a high molecular weight is not required, the resin may be produced by only the esterification reaction or the transesterification reaction.

[0076] The blending ratio of the polyvalent carboxylic acids (a1) and the polyhydric alcohols (a2) is preferably 1 to 3 equivalents, particularly preferably 1.1 to 2.2 equivalents, and even more preferably 1.2 to 1.7 equivalents of the polyhydric alcohols (a2) per equivalent of the polyvalent carboxylic acids (a1). If the blending ratio of the polyhydric alcohols (a2) is too low, the acid value tends to be high, making it difficult to obtain a high molecular weight, while if it is too high, the yield tends to be low.

[0077] [Esterification reaction or transesterification reaction] In the esterification reaction or transesterification reaction, a catalyst is usually used, and specific examples include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are 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 the hue of the resulting reaction product.

[0078] The amount of the catalyst to be added is preferably 1 to 10,000 ppm, particularly preferably 10 to 5,000 ppm, and further preferably 20 to 3,000 ppm, based on the total weight of the copolymerization components. If the amount is too small, the polymerization reaction tends to proceed insufficiently, whereas if the amount is too large, there is no advantage such as shortening the reaction time, and side reactions tend to occur easily.

[0079] 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 not to proceed sufficiently, while if it is too high, side reactions such as decomposition tend to occur easily. Furthermore, although the pressure during the reaction is usually normal pressure, it is also preferable to perform the reaction under pressure to increase the reaction temperature and efficiently proceed with the reaction.

[0080] As reaction conditions for the polycondensation reaction carried out after the above-mentioned esterification reaction or transesterification reaction, it is preferable to further blend the same amount of the same catalyst as that used in the above-mentioned esterification reaction or transesterification reaction, set the reaction temperature to preferably 220 to 280°C, particularly preferably 230 to 270°C, and gradually reduce the pressure of the reaction system until the reaction is finally carried out at 5 hPa or less. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur easily.

[0081] In addition, when obtaining a polyester resin having a carboxy group in the side chain, a method of reacting a polycarboxylic acid anhydride with a hydroxyl group-containing prepolymer obtained by copolymerizing a polycarboxylic acid (a1) other than a polycarboxylic acid anhydride with a polyhydric alcohol (a2) is preferred from the viewpoint of productivity.

[0082] The temperature for the esterification reaction between the polycarboxylic acids (a1) and the polyhydric alcohols (a2) is usually 180 to 280° C., and the reaction time is usually 60 minutes to 8 hours.

[0083] The temperature in the polycondensation is usually 200 to 280° C., and the reaction time is usually 20 minutes to 4 hours. The polycondensation is preferably carried out under reduced pressure.

[0084] The polyester resin (A) can also be produced by a well-known method other than the above, for example, by subjecting a polycarboxylic acid (a1) and a polyhydric alcohol (a2) to an esterification reaction, optionally in the presence of a catalyst, to obtain a prepolymer, followed by polycondensation and further depolymerization.

[0085] For depolymerization, it is preferable to use trivalent or higher polycarboxylic acids (a1-2) having 0 or 1 acid anhydride group in terms of adhesive strength. As the trivalent or higher polycarboxylic acids (a1-2) having 0 or 1 acid anhydride group, those described above for the polycarboxylic acids (a1) can be used. Among them, trivalent or higher polycarboxylic acids (a1-2) having 1 acid anhydride group are preferred in terms of suppressing a decrease in molecular weight, more preferably trimellitic anhydride and hydrogenated trimellitic anhydride, and particularly preferably trimellitic anhydride in terms of a low dielectric loss tangent. The temperature for depolymerization is usually 200 to 260°C, and the reaction time is usually 10 minutes to 3 hours.

[0086] During depolymerization, when the entire polycarboxylic acids (a1) are taken as 100 mol %, the number of acid anhydride groups is When the trivalent or higher polyvalent carboxylic acid (a1-2) in which is 0 or 1 is used in an amount of more than 20 mol %, the resin Therefore, the molecular weight of the polycarboxylic acid (a1) may be significantly reduced. When the number of acid anhydride groups is 0 or 1, the polyvalent carboxylic acids (a1-2) having 3 or more carboxylic acids are It is preferable to carry out depolymerization using 20 mol % or less, more preferably 1 to 15 mol %, and particularly preferably 1 to 15 mol %. The content is preferably 2 to 10 mol %, and more preferably 3 to 8 mol %.

[0087] Thus, a polyester resin (A) having a very small dielectric loss tangent compared to conventional resins can be obtained. Furthermore, the polyester resin (A) having a very small dielectric loss tangent is very useful as a raw material for adhesives used for bonding electronic materials and components, because it can suppress transmission loss in the high frequency range.

[0088] In the present invention, it is preferable that the polyester resin (A) is soluble in a non-halogen organic solvent in order to prepare the adhesive composition described below. If the solubility in such an organic solvent is insufficient, it tends to be difficult to prepare the adhesive composition.

[0089] 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; alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and isobutyl 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.

[0090] [Curing agent (B)] The adhesive composition of the present invention preferably further contains a curing agent (B). By including the curing agent (B), functional groups in the polyester resin (A) react with the curing agent (B) having a functional group reactive with the functional group, resulting in curing, and an adhesive with excellent adhesive strength, heat resistance, and durability can be obtained. In addition, as with polyfunctional acrylates, the curing agents may react with each other and become entangled with the polyester resin (A), resulting in pseudo-crosslinking. Examples of such curing agents (B) include polyisocyanate compounds, polyepoxy compounds, polyfunctional (meth)acrylic monomers, and polyfunctional urethane (meth)acrylates. Among these, compounds having a functional group that reacts with at least one of the hydroxyl group and the carboxyl group contained in the polyester resin (A) are preferred, and among these, polyepoxy compounds are preferred in terms of solder heat resistance.

[0091] Examples of the polyisocyanate compounds include aromatic isocyanate curing agents such as 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, and naphthalene diisocyanate curing agents such as 1,5-naphthalene diisocyanate; Examples of suitable curing agents include alicyclic isocyanate curing agents such as cyclohexanediisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidenedicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, and norbornane diisocyanate; aliphatic isocyanate curing agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts, biurets, and isocyanurates of the above-mentioned isocyanate compounds. The polyisocyanate compounds may also be used in which the isocyanate moiety is blocked with phenol, lactam, or the like. These polyisocyanate compounds may be used alone or in combination. Among these, from the viewpoint of compatibility, alicyclic isocyanate curing agents and aliphatic isocyanate curing agents are preferred, and alicyclic isocyanate curing agents are particularly preferred, with isocyanurates and adducts of isophorone diisocyanate being even more preferred.

[0092] The equivalent weight (functional group molar ratio) of isocyanate groups to hydroxyl groups 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. If the equivalent weight is too large, the adhesive strength and stability over time of the adhesive sheet tend to be insufficient, whereas if it is too small, the long-term durability and cohesive strength in a humid and hot environment tend to be insufficient, and the dielectric properties tend to be poor.

[0093] Examples of the polyepoxy compounds include bifunctional glycidyl ethers such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; multifunctional glycidyl ethers such as phenol novolac glycidyl ether and cresol novolac glycidyl ether; glycidyl esters such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; and alicyclic or aliphatic epoxides such as triglycidyl isocyanurate, 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. These polyepoxy compounds may be used alone or in combination. Among these, glycidyl ethers and glycidyl esters are preferred from the viewpoint of reactivity, glycidyl ethers are preferred from the viewpoint of wet heat durability, and multifunctional types are preferred from the viewpoint of heat resistance.

[0094] 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 even more preferably 200 g / eq or less. If the epoxy equivalent of the polyepoxy compound is too high, the crosslink density after crosslinking will be low, resulting in poor heat resistance, or a large amount of polyepoxy compound will need to be added to achieve high crosslink density, resulting in poor dielectric properties.

[0095] Furthermore, if the polyepoxy compound contains a polyepoxy compound containing a nitrogen atom (a nitrogen atom-containing polyepoxy compound), the curing time of the adhesive layer can be shortened, which is preferable.

[0096] Examples of nitrogen atom-containing polyepoxy compounds include glycidylamine compounds such as tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, tetraglycidyl bisaminomethylcyclohexanone, and N,N,N',N'-tetraglycidyl-m-xylenediamine.

[0097] The equivalent weight (functional group molar ratio) of epoxy groups to carboxy groups is preferably 0.5 to 5, more preferably 0.8 to 3, particularly preferably 0.9 to 2, and even more preferably 1 to 1.5. If the equivalent weight is too large, the adhesive strength and low moisture absorption tend to be insufficient and the dielectric properties tend to be poor, whereas if the equivalent weight is too small, the long-term durability and heat resistance in a humid and hot environment tend to be insufficient.

[0098] The equivalent weight (functional group molar ratio) of epoxy groups to carboxy groups (COOH) is calculated from the acid value of the polyester resin (A) and the epoxy equivalent weight (g / eq) of the blended polyepoxy compound using the following formula 4. [Formula 4] Equivalent weight of epoxy to COOH = (a ÷ WPE) / (AV ÷ 56.1 ÷ 1000 × b) a: Weight (g) of polyepoxy compound used in the formulation WPE: Epoxy equivalent of polyepoxy compound (g / eq) AV: Acid value of polyester resin (A) (mgKOH / g) b: Weight (g) of polyester resin (A) used in the blend

[0099] [Adhesive composition] The adhesive composition of the present invention contains a polyester resin (A), and further contains a curing agent (B) and other components as required. 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 or more, and even more preferably 70% by weight or more, based on the total solid content, with the upper limit usually being 99% by weight. When the content is within the above range, the effects of the present invention are more easily obtained.

[0100] 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 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, per 100 parts by weight of the polyester resin (A). If the content of the curing agent (B) is too low, the heat-resistant adhesive strength and long-term durability under humid and hot environments tend to be insufficient, while if it is too high, the adhesive strength and low moisture absorption tend to be insufficient and the dielectric properties tend to be inferior.

[0101] [Other ingredients] To further improve its functionality, the adhesive composition of the present invention may contain other components in addition to the polyester resin (A) and the curing agent (B), such as inorganic fillers, coupling agents such as silane coupling agents, ultraviolet inhibitors, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, elasticity reducing agents, diluents, antifoaming agents, ion trapping agents, leveling agents, and catalysts. When the adhesive composition of the present invention contains other components, the content of the other components is preferably 70% by weight or less, more preferably 0.05 to 60% by weight, particularly preferably 0.1 to 50% by weight, and even more preferably 0.2 to 40% by weight, based on the total solid content.

[0102] The adhesive composition of the present invention can be obtained, for example, by preparing the polyester resin (A) and necessary optional components, and blending and dispersing them during the production of the polyester resin (A), or by blending them into a solution of the polyester resin (A) dissolved in an organic solvent, and dispersing them using a mixing roller or the like.

[0103] The adhesive composition of the present invention may also contain a solvent in order to adjust the viscosity of the adhesive composition appropriately and to facilitate handling when forming a coating film. The solvent is used to ensure ease of handling and workability when molding the adhesive composition, and there are no particular restrictions on the amount used.

[0104] 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; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; alcohols such as methanol and ethanol; alkanes such as hexane and cyclohexane; aromatics such as toluene and xylene. The above-mentioned solvents may be used alone, or two or more may be mixed in any combination and ratio.

[0105] <Adhesive> In the present invention, the adhesive can be obtained by curing the adhesive composition. In the present invention, "curing" means intentionally crosslinking the adhesive composition by heat and / or light, and the degree of crosslinking can be controlled depending on the desired physical properties and applications.

[0106] The degree of crosslinking can be confirmed by the gel fraction of the adhesive, and the gel fraction is preferably 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 or more. If the gel fraction is too low, the heat resistance and long-term durability in a humid and hot environment tend to be insufficient, while if it is too high, the adhesive strength tends to be insufficient. The gel fraction is an index of the degree of cure and is calculated, for example, by the following method. That is, an adhesive sheet (without a release sheet) consisting of an adhesive layer formed on a polymer sheet (e.g., a PET film) serving as a substrate is wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours, and the gel fraction is calculated as the weight percentage of the insoluble adhesive component remaining in the wire netting after immersion relative to the weight of the adhesive component before immersion, excluding the weight of the substrate.

[0107] The method for curing the adhesive composition of the present invention when it is cured or semi-cured to form an adhesive varies depending on the components and their amounts in the adhesive composition, but typically includes heating conditions of 80 to 200°C for 1 minute to 10 hours.

[0108] When the adhesive composition of the present invention is cured using a curing agent, a catalyst may be used. Examples of such catalysts include imidazole compounds such as 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole; tertiary amines such as triethylamine, triethylenediamine, N'-methyl-N-(2-dimethylaminoethyl)piperazine, 1,8-diazabicyclo(5,4,0)-undecene-7, 1,5-diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; and compounds obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, or the like; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diaryliodonium hexafluoroantimonate; and triphenylphosphine. Among these, tertiary amines such as 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 obtained by converting these tertiary amines into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc. are preferred in terms of thermosetting properties, heat resistance, adhesion to metals, and storage stability after formulation. The amount of the curing agent (B) added is preferably 0.01 to 1 part by weight per 100 parts by weight of the polyester resin. This range further enhances the catalytic effect on the reaction between the polyester resin (A) and the curing agent (B), thereby achieving strong adhesive properties.

[0109] [Application] The adhesive of the present invention has excellent initial adhesion, low moisture absorption, and long-term durability in a humid and hot environment, and is therefore effective for bonding substrates made of various materials such as resins and metals. It is particularly suitable as an adhesive for producing laminates of metal layers and plastic layers, for example, as an adhesive used for bonding electronic materials. Examples of the "electronic material" in the present invention include flexible printed circuit boards, coverlays, and bonding sheets. Examples of products produced by bonding electronic materials include flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards. A flexible laminate is, for example, a laminate obtained by sequentially laminating a flexible substrate, an adhesive layer, and a conductive metal layer made of copper, aluminum, or an alloy thereof, and the adhesive of the present invention can be used as the adhesive constituting the adhesive layer. 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. [Example]

[0110] The present invention will be explained in more detail below with reference to examples, but the present invention does not exceed the gist of the present invention. The present invention is not limited to the following examples. In the examples, "parts" and "%" indicate weights. It means a quantity standard.

[0111] Example 1 [Production of Polyester Resin (A-1)] Into a reactor equipped with a thermometer, a stirrer, a rectification column, and a nitrogen inlet tube, 7.5 parts (0.039 mol) of dimethyl terephthalate (a1-1) as polycarboxylic acids (a1), 8.8 parts (0.045 mol) of dimethyl isophthalate (a1-1), 9.4 parts (0.039 mol) of dimethyl 2,6-naphthalenedicarboxylate (a1-1), 1.2 parts (0.006 mol) of trimellitic anhydride (a1-2), and poly 9.6 parts (0.155 mol) of ethylene glycol as the hydric alcohol (a2), 473.6 parts (0.122 mol) of hydrogenated polybutadiene diol (a2-1) (GI-3000 (manufactured by Nippon Soda Co., Ltd.) having a number average molecular weight of 3870), and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the internal temperature was raised to 270°C over 2.5 hours, and an esterification reaction was carried out at 270°C for 1.5 hours. Next, 0.1 parts 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, and 9.9 parts (0.052 mol) of trimellitic anhydride (TMAn) was added and a depolymerization reaction was carried out at 230°C for 1 hour to obtain a polyester resin (A-1).

[0112] <Examples 2 to 4 and Comparative Example 1> [Production of Polyester Resins (A-2) to (A-4) and (A'-1)] Polyester resins (A-2) to (A-4) and (A'-1) were obtained in the same manner as for polyester resin (A-1), except that the resin composition was changed as shown in Table 1.

[0113] <Comparative Example 2> [Production of Polyester Resin (A'-2)] A reactor equipped with a thermometer, a stirrer, a rectification column, and a nitrogen inlet tube was charged with 19.3 parts (0.132 mol) of adipic acid and 17.1 parts (0.084 mol) of sebacic acid as polycarboxylic acids (a1), 13.4 parts (0.217 mol) of ethylene glycol as polyhydric alcohols (a2), 448.2 parts (0.195 mol) of hydrogenated polybutadiene diol (a2-1) (GI-2000 (manufactured by Nippon Soda Co., Ltd.)) having a number average molecular weight of 2,300, 2.0 parts (0.015 mol) of trimethylolpropane, and 0.1 parts of tetrabutyl titanate as a catalyst. The internal temperature was raised to 270°C over 2.5 hours, and an esterification reaction was carried out at 270°C for 1.5 hours. Next, 0.1 parts 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).

[0114] <Comparative Examples 3 and 4> [Production of Polyester Resins (A'-3) and (A'-4)] Polyester resins (A'-3) and (A'-4) were obtained in the same manner as for polyester resin (A'-2), except that the resin composition was changed as shown in Table 1.

[0115] The compositions shown in Table 1 below are the composition ratios (resin composition ratios) of the finished products, and are the relative ratios (molar ratios) of the amounts of the constituent monomers of the resulting polyester resins. In Table 1, the abbreviations are as follows: "IPA": Isophthalic acid (a1-1) [DMT]: Dimethyl terephthalate (a1-1) "DMI": Dimethyl isophthalate (a1-1) "NDCM": 2,6-naphthalenedicarboxylic acid dimethyl (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

[0116] The resin composition (structural parts derived from components) of the obtained polyester resin is shown in Table 1 below.

[0117] The polyester resin's glass transition temperature (°C), acid value (mgKOH / g), peak top molecular weight (Mp), weight average molecular weight (Mw), dielectric properties (dielectric constant 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%) were measured according to the specifications herein. The physical properties of the polyester resin are shown in Table 2 below. In addition, since the dielectric properties of Comparative Examples 2 to 4 were poor and the problems of the present invention could not be solved, the probe tack was not evaluated.

[0118] [Table 1]

[0119] [Table 2]

[0120] <Curing agent (B)> The following was prepared as the curing agent (B). (B-1): Tetraglycidyldiaminodiphenylmethane ("jER604" manufactured by Mitsubishi Chemical Corporation)

[0121] An adhesive composition was produced as follows using the polyester resin (A) and curing agent (B) obtained above.

[0122] <Example 5> The polyester resin (A-1) obtained above was diluted with toluene to a solid content concentration of 50%, and 2.5 parts of curing agent (B-1) (solid content) was blended with this polyester resin (A-1) solution (100 parts as solid content), and the mixture was further diluted with toluene to a total solid content of 50%, followed by stirring and mixing, to obtain an adhesive composition.

[0123] <Examples 6 to 12, Comparative Examples 5 and 6> An adhesive composition was obtained in the same manner as in Example 5, except that the components were blended as shown in Table 3 below. The adhesive compositions obtained were evaluated as follows, and the evaluation results are shown in Table 3 below.

[0124] [Adhesion strength (peel strength) (PI / adhesive layer / Cu)] The adhesive composition prepared above was applied to a 50 μm-thick polyimide film "Kapton 200H" (manufactured by DuPont-Toray Co., Ltd.) with an applicator and then dried at 120°C for 5 minutes to form an adhesive layer with a dry thickness of 25 μm. Next, a 30 μm-thick rolled copper foil was laminated to the adhesive layer surface of the adhesive-coated polyimide film (lamination conditions: 170°C, 0.2 MPa, feed rate 1.5 m / min), and then heat-treated and cured in an oven at 160°C for 4 hours to obtain a laminate. The laminate obtained above was cut into a 1 cm wide piece to be used as a test piece. The test piece was fixed to a 2 mm thick glass plate using double-sided tape, and the tensile peel strength of the test piece was measured using a peel tester under an environment of 23°C temperature and 50% RH relative humidity (peel speed: 50 mm / min, peel angle: 180°).

[0125] [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. A release-treated PET film was then attached to the adhesive layer to protect its surface, and the adhesive layer was 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 4 cm x 4 cm size. After peeling off the release film on one side, the sheet was wrapped in a 200-mesh SUS wire netting and immersed in toluene at 23°C for 24 hours. The gel fraction was determined as the weight percentage of the insoluble adhesive component remaining in the wire netting relative to the weight of the adhesive before immersion.

[0126] 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.

[0127] [Probe Tack] The adhesive composition prepared above was applied to a 38 μm-thick PET film ("Lumirror T60" manufactured by Toray Industries, Inc.) with an applicator and dried at 120° C. for 5 minutes to produce a sheet of adhesive composition with a dry film thickness of 25 μm. A release-treated PET film was then attached to the adhesive layer to protect its surface, and the adhesive sheet was then obtained by heat-treating and curing in an oven at 160° C. for 4 hours. The adhesive sheet obtained above was cut into a size of 12 mm x 12 mm, and the release-treated PET film was then peeled off. The adhesive sheet was then tested at 23°C and 50% RH using a probe tack tester (TE-6001, manufactured by Tester Sangyo Co., Ltd.) with a probe diameter of 5 mm, a push-in speed of 10 mm / sec, a pull-up speed of 10 mm / sec, a pressure time of 5 seconds, and an application pressure of 1000 gf / cm. 2 was measured.

[0128] [Table 3]

[0129] From the results in the above table, the adhesive compositions of Examples 5 to 12, which used the polyester resins (A-1) to (A-4) of Examples 1 to 4, were adhesive compositions with excellent dielectric properties and adhesive properties (probe tack). On the other hand, the adhesive compositions of Comparative Examples 5 and 6, which used the polyester resin (A'-1) of Comparative Example 1, were poor in adhesiveness. Also, the polyester resins (A'-2) to (A'-4) of Comparative Examples 2 to 4 were poor in dielectric tangent. [Industrial Applicability]

[0130] The adhesive composition of the present invention is an adhesive composition containing a polyester resin (A), and has an extremely low dielectric constant and dielectric dissipation factor, as well as excellent adhesion. Therefore, it is effective as an adhesive for producing metal-plastic laminates, for example, flexible laminates such as flexible copper-clad laminates and flexible printed circuit boards.

Claims

1. An adhesive composition containing a polyester resin (A) having a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), the content of the structural moiety derived from the aromatic polycarboxylic acid (a1-1) is 20 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1); the content of structural moieties derived from polydiene diols and / or hydrogenated polydiene diols (a2-1) is 50% by weight or more of the total weight of the polyester resin (A), An adhesive composition characterized in that the acid value of the polyester resin (A) is 3 mgKOH / g or more.

2. An adhesive composition containing a polyester resin (A) having a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), the content of the structural moiety derived from the aromatic polycarboxylic acid (a1-1) is 20 mol % or more of the total structural moieties derived from the polycarboxylic acid (a1); the content of structural moieties derived from polydiene diols and / or hydrogenated polydiene diols (a2-1) is 50% by weight or more of the total weight of the polyester resin (A), The adhesive composition is characterized in that the polycarboxylic acids include a trivalent or higher polycarboxylic acid (a1-2) having 0 or 1 acid anhydride group.

3. An adhesive composition containing a polyester resin (A) having a structural moiety derived from a polycarboxylic acid (a1) and a structural moiety derived from a polyhydric alcohol (a2), the content of structural moieties derived from aromatic polycarboxylic acids (a1-1) is 70 mol % or more of the total structural moieties derived from polycarboxylic 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 of the total weight of the polyester resin (A).

4. The adhesive composition according to any one of claims 1 to 3, 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.

5. 4. The adhesive composition according to claim 1, wherein the polyester resin (A) has a glass transition temperature of -60 to 60°C.

6. 4. The adhesive composition according to claim 2, wherein the polyester resin (A) has an acid value of 3 mgKOH / g or more.

7. An adhesive composition containing a polyester-based resin described in any one of claims 1 to 3, characterized in that at least one of the polyvalent carboxylic acids (a1) and the polyhydric alcohols (a2) contains a condensed polycyclic aromatic compound.

8. An adhesive composition containing a polyester-based resin as described in claim 1 or 3, characterized in that the polyvalent carboxylic acids (a1) include polyvalent carboxylic acids (a1-2) of three or more valences having 0 or 1 acid anhydride group number.

9. An adhesive composition described in any one of claims 1 to 3, characterized in that the polyester resin (A) is amorphous.

10. The adhesive composition according to any one of claims 1 to 3, further comprising a curing agent (B).

11. An adhesive composition as described in claim 10, characterized in that the content of the curing agent (B) is 30 parts by weight or less per 100 parts by weight of the polyester resin (A).

12. An adhesive obtained by curing the adhesive composition according to any one of claims 1 to 3.

13. The adhesive according to claim 12, which is used for bonding electronic materials.

14. The adhesive described in Claim 13, characterized in that the electronic material component is at least one selected from flexible copper-clad laminates, coverlays, and bonding sheets.

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