CN114555749B - Adhesive composition for flexible printed circuit board, adhesive for flexible printed circuit board, and flexible printed circuit board - Google Patents

Adhesive composition for flexible printed circuit board, adhesive for flexible printed circuit board, and flexible printed circuit board Download PDF

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Publication number
CN114555749B
CN114555749B CN202080073175.9A CN202080073175A CN114555749B CN 114555749 B CN114555749 B CN 114555749B CN 202080073175 A CN202080073175 A CN 202080073175A CN 114555749 B CN114555749 B CN 114555749B
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polyester resin
acid
beta
dimer
content
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CN114555749A (en
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中根宇之
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Mitsubishi Chemical Corp
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Mitsubishi Chemical Corp
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J167/00Adhesives based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Adhesives based on derivatives of such polymers
    • C09J167/02Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16Dicarboxylic acids and dihydroxy compounds
    • C08G63/18Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/181Acids containing aromatic rings
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78Preparation processes
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L63/00Compositions of epoxy resins; Compositions of derivatives of epoxy resins
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J163/00Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09JADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J167/00Adhesives based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Adhesives based on derivatives of such polymers
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/03Use of materials for the substrate

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

An adhesive composition for a flexible printed circuit board, which has excellent long-term durability and excellent adhesion in a hot and humid environment, is characterized by comprising a polyester resin (A1), wherein the polyester resin (A1) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, and the polyester resin (A1) satisfies the following conditions. [1] The ester bond concentration was 7 mmol/g or less. [2] The acid value is 3mgKOH/g or more. [3] The glass transition temperature (Tg) is-5 ℃ or higher.

Description

Adhesive composition for flexible printed circuit board, adhesive for flexible printed circuit board, and flexible printed circuit board
Technical Field
The present invention relates to an adhesive composition for a flexible printed circuit board containing a polyester resin, and an adhesive obtained by curing the adhesive composition. More specifically, the present invention relates to an adhesive having high adhesion in addition to long-term durability under hot and humid environments, and an adhesive composition before curing the adhesive.
Background
Conventionally, polyester resins are used in a wide variety of fields such as films, plastic bottles, fibers, toners, motor parts, adhesives, and binders because of their excellent heat resistance, chemical resistance, durability, and mechanical strength. Also known are: since polyester resins have high polarity due to their polymer structure, they exhibit excellent adhesion to polar polymers such as polyesters, polyvinyl chloride, polyimide, and epoxy resins, and to metallic materials such as copper and aluminum. By utilizing this characteristic, the use of the adhesive as an adhesive for producing a laminate of metal and plastic, for example, an adhesive for producing a flexible copper-clad laminate, a flexible printed board, or the like has been studied.
For example, patent document 1 proposes a thermosetting adhesive sheet excellent in dimensional stability upon curing, adhesion after curing, heat resistance, bendability, electrical insulation, low dielectric constant, and low dielectric loss tangent. The thermosetting adhesive sheet is formed from a thermosetting composition containing a resin (for example, a polyester resin), an organometallic compound, and a trifunctional or higher epoxy-containing compound, wherein the total amount of reactive functional groups capable of reacting with at least either the organometallic compound or the epoxy-containing compound and functional groups having heteroatoms other than halogen in the resin is 0.01mmol/g or more and 9mmol/g or less.
Patent document 2 proposes a copolyester excellent in moist heat resistance and cationic acidity resistance and having compatibility with an epoxy resin and adhesion, and an adhesive composition containing the same. The copolyester is formed by aromatic dicarboxylic acid component and dimeric alcohol, 1 st glycol, 2 nd glycol or oxyacid and alkylene glycol with 2-10 carbon atoms.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2017-031301
Patent document 2: japanese patent laid-open No. 2003-183365
Disclosure of Invention
Problems to be solved by the invention
However, in recent years, there is a tendency that physical properties required for adhesives used for flexible copper-clad laminates, flexible printed boards, and the like are as follows: in addition to curability, heat resistance, and adhesion, long-term durability in a hot and humid environment is strongly demanded from the viewpoint of reliability. However, if the resin is made to have a low polarity in order to improve the wet heat durability, there is a problem that the adhesiveness is generally greatly lowered, and it is difficult to achieve a high level of these properties.
For example, in the technique disclosed in patent document 1, a polycarboxylic acid or a polyol having a long-chain alkyl group is used in a large amount in order to reduce the dielectric constant, dielectric loss tangent, and water absorption, and therefore, there is a problem that the adhesiveness is lowered. In patent document 1, further improvement is demanded in view of long-term durability under a hot and humid environment without consideration.
In addition, when the adhesive composition disclosed in patent document 2 is used for producing a copper-clad laminate or the like, it is assumed that the adhesive composition is excellent in long-term durability under a hot and humid environment. However, this copolyester has a problem of poor adhesion and heat resistance because it contains a diol containing an ether bond such as polypropylene glycol as a copolymerization component or is not provided with an acid value forming a reaction site for reaction with an epoxy resin.
Accordingly, the present invention provides an adhesive composition having excellent long-term durability in a hot and humid environment and further having high adhesion, and an adhesive obtained by curing the adhesive composition.
Solution for solving the problem
Accordingly, the present inventors have made intensive studies in view of the above circumstances, and as a result, have found that an adhesive composition (first embodiment) of the present invention, wherein an adhesive composition containing a polyester resin (A1) satisfying the following conditions is excellent in long-term durability under a hot and humid environment and has high adhesion.
[1] The ester bond concentration was 7 mmol/g or less.
[2] The acid value is 3mgKOH/g or more.
[3] The glass transition temperature (Tg) is-5 ℃ or higher.
The adhesive composition of the present invention can be obtained by containing the polyester resin (A2) satisfying the following conditions in addition to the first embodiment (second embodiment).
[I] the polycarboxylic acid contains 25 mol% or more of an aromatic polycarboxylic acid.
[ II ] the polycarboxylic acid contains a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group.
[ III ] the ester bond concentration is 7 mmol/g or less.
[ IV ] the acid value is 3mgKOH/g or more.
The adhesive composition of the present invention can be obtained by containing a polyester resin according to any one of the following (1) to (4) in addition to the first and second aspects (third aspect).
(1) A polyester resin (A3) having a glass transition temperature (Tg) of-5 ℃ or higher and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
(2) An acid value of 3mgKOH/g or more, and a dielectric loss tangent (alpha) at 10GHz at a temperature of 23 ℃ under a relative humidity of 50% RH of 0.005 or less.
(3) A polyester resin (A5) having a glass transition temperature (Tg) of-5 ℃ or higher, an acid value of 3mgKOH/g or higher, and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
(4) A polyester resin (A6) having a dielectric loss tangent (alpha) of 0.003 or less at 10GHz under an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
The present invention further provides an adhesive agent obtained by curing the adhesive agent composition.
The invention also provides a flexible printed circuit board which is formed by using the adhesive.
As described in patent document 1, in general, polycarboxylic acids and polyols having long-chain alkyl groups are used in large amounts to reduce water absorption, but on the other hand, adhesiveness and long-term durability in a hot and humid environment are reduced.
The inventors found that: the present invention has been completed by adjusting the composition of the monomers constituting the polyester resin to optimize the ester bond concentration, acid value, glass transition temperature, and the like, thereby achieving excellent long-term durability in a hot and humid environment and excellent adhesion.
ADVANTAGEOUS EFFECTS OF INVENTION
The adhesive composition according to one embodiment of the present invention is an adhesive composition containing a polyester resin (A1), wherein the polyester resin (A1) contains a structural unit derived from a polycarboxylic acid type and a structural unit derived from a polyhydric alcohol type, and the polyester resin (A1) has the following conditions, and thus has the effects of low hygroscopicity, non-tackiness before curing, initial tackiness after curing, and excellent long-term durability in a hot-humid environment.
[1] The ester bond concentration was 7 mmol/g or less.
[2] The acid value is 3mgKOH/g or more.
[3] The glass transition temperature (Tg) is-5 ℃ or higher.
Further, when the polyester resin (A1) contains an aromatic polycarboxylic acid as the polycarboxylic acid and the content of the aromatic polycarboxylic acid is 25 mol% or more based on the entire polycarboxylic acid, the long-term durability in a hot and humid environment is more excellent.
In addition, if the polyester resin (A1) has a carboxyl group in a side chain, the curing speed and the heat resistance after curing are more excellent.
Further, when the polyester resin (A1) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyhydric alcohols, and the total content (α+β) of the dimer acids to the entire polycarboxylic acids and the total content (α+β) of the dimer alcohols to the entire polyhydric alcohols is 5 mol% or more, the polyester resin is low in hygroscopicity and excellent in long-term durability under a hot and humid environment.
Further, when the polyester resin (A1) contains a bisphenol skeleton-containing monomer as the polyhydric alcohol and the content of the bisphenol skeleton-containing monomer is 10 mol% or more based on the entire polyhydric alcohol, the polyester resin has low hygroscopicity and is more excellent in long-term durability under a hot and humid environment.
In another embodiment of the present invention, the adhesive composition contains a polyester resin (A2), wherein the polyester resin (A2) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, and the polyester resin (A2) satisfies the following conditions, and therefore has the effects of low hygroscopicity, excellent long-term durability in a hot and humid environment, and excellent adhesiveness.
[I] the polycarboxylic acid contains 25 mol% or more of an aromatic polycarboxylic acid.
[ II ] the polycarboxylic acid contains a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group.
[ III ] the ester bond concentration is 7 mmol/g or less.
[ IV ] the acid value is 3mgKOH/g or more.
When the glass transition temperature of the polyester resin (A2) is at least-5 ℃, the initial adhesion and non-tackiness are more excellent.
The polyester resin (A2) is a polyester resin obtained by a depolymerization step using a polycarboxylic acid (x 1), and has more excellent adhesion.
The polyester resin (A2) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyalcohols, and the total content (α+β) of the dimer acids to the total content (α) of the polycarboxylic acids and the total content (β) of the dimer alcohols to the total polyols is 5 mol% or more, thereby having low hygroscopicity and further excellent long-term durability in a hot and humid environment.
When the polyester resin (A2) contains a bisphenol skeleton-containing monomer as the polyhydric alcohol and the content of the bisphenol skeleton-containing monomer is 10 mol% or more based on the entire polyhydric alcohol, the polyester resin has low hygroscopicity and is more excellent in long-term durability under a hot and humid environment.
Another embodiment of the adhesive composition of the present invention is an adhesive composition containing a polyester resin (A3), wherein the polyester resin (A3) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, and the polyester resin (A3) has a glass transition temperature (Tg) of-5 ℃ or higher and a dielectric loss tangent (α) of 0.005 or less at 10GHz in an environment of a relative humidity of 50% rh at a temperature of 23 ℃, and therefore exhibits the effects of low dielectric constant and dielectric loss tangent, particularly low dielectric loss tangent, initial adhesion after curing, and further excellent long-term durability in a hot-humid environment.
In addition, as another embodiment of the present invention, an adhesive composition comprising a polyester resin (A4), wherein the polyester resin (A4) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, the acid value of the polyester resin (A4) is 3mgKOH/g or more, and the dielectric loss tangent (α) at 10GHz in an environment of a relative humidity of 50% rh at a temperature of 23 ℃ is 0.005 or less, and therefore, the adhesive composition exhibits the effects of low dielectric constant and dielectric loss tangent, particularly low dielectric loss tangent, initial adhesiveness after curing, and further excellent long-term durability in a humid and hot environment.
In addition, as another embodiment of the present invention, an adhesive composition comprising a polyester resin (A5), wherein the polyester resin (A5) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, the polyester resin (A5) has a glass transition temperature (Tg) of-5 ℃ or higher, an acid value of 3mgKOH/g or higher, and a dielectric loss tangent (α) at 10GHz in an environment of a relative humidity of 50% rh at a temperature of 23 ℃ or lower of 0.005 or lower, and therefore exhibits the effects of low dielectric constant and dielectric loss tangent, in particular, low dielectric loss tangent, initial adhesion after curing, and further excellent long-term durability in a hot-humid environment.
In addition, as another embodiment of the adhesive composition of the present invention, an adhesive composition containing a polyester resin (A6), wherein the polyester resin (A6) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, and the polyester resin (A6) has a dielectric loss tangent (α) of 0.003 or less at 10GHz in an environment of a relative humidity of 50% rh at a temperature of 23 ℃, and therefore exhibits the effects of low dielectric constant and low dielectric loss tangent, particularly low dielectric loss tangent, initial adhesion after curing, and further excellent long-term durability in a hot and humid environment.
When the polyepoxide compound (B) is further contained, an adhesive layer excellent in heat resistance, adhesion and solder heat resistance can be obtained.
Further, when the content of the polyester resin (A1) in the polyester resin exceeds 50% by weight, the polyester resin has low hygroscopicity and further excellent long-term durability under a hot and humid environment.
The adhesive composition of the present invention is particularly suitable for an adhesive for producing a laminate of metal and plastic, for example, an adhesive used for producing a flexible laminate such as a flexible copper-clad laminate and a flexible printed board, a coverlay, a bonding sheet, and the like, and is more suitable for an adhesive for a flexible printed board. Further, since the adhesive composition and the obtained adhesive of the present invention have the above-described excellent effects, the reliability of the flexible printed circuit board using the adhesive, which is excellent in long-term durability under a hot and humid environment, is improved.
Detailed Description
The following describes the constitution of the present invention in detail, but they are descriptions showing an example of the preferred embodiment.
In the present invention, "class" denoted after the name of a compound is a concept including derivatives of the compound in addition to the compound. For example, the term "carboxylic acid" includes carboxylic acid derivatives such as carboxylates, carboxylic acid anhydrides, carboxylic acid halides, carboxylic acid esters, and the like, in addition to carboxylic acids.
First, the adhesive composition according to the first aspect of the present invention is characterized by containing a polyester resin (A1) satisfying the following conditions.
[1] The ester bond concentration was 7 mmol/g or less.
[2] The acid value is 3mgKOH/g or more.
[3] The glass transition temperature (Tg) is-5 ℃ or higher.
Next, the adhesive composition according to the second aspect of the present invention is characterized by containing a polyester resin (A2) satisfying the following conditions.
[I] the polycarboxylic acid contains 25 mol% or more of an aromatic polycarboxylic acid.
[ II ] the polycarboxylic acid contains a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group.
[ III ] the ester bond concentration is 7 mmol/g or less.
[ IV ] the acid value is 3mgKOH/g or more.
The adhesive composition according to the third aspect of the present invention is characterized by comprising a polyester resin according to any one of the following (1) to (4).
(1) A polyester resin (A3) having a glass transition temperature (Tg) of-5 ℃ or higher and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
(2) An acid value of 3mgKOH/g or more, and a dielectric loss tangent (alpha) at 10GHz at a temperature of 23 ℃ under a relative humidity of 50% RH of 0.005 or less.
(3) A polyester resin (A5) having a glass transition temperature (Tg) of-5 ℃ or higher, an acid value of 3mgKOH/g or higher, and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
(4) A polyester resin (A6) having a dielectric loss tangent (alpha) of 0.003 or less at 10GHz under an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
The following describes the first to third embodiments in order.
First mode
The adhesive composition of the present invention contains at least a polyester resin (A1), wherein the polyester resin (A1) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin (A1) will be described.
< Polyester resin (A1) >)
The polyester resin (A1) preferably contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and is a resin obtained by bonding a polycarboxylic acid and a polyhydric alcohol by an ester bond.
[ Polycarboxylic acids ]
Examples of the polycarboxylic acid include aromatic polycarboxylic acids described below; alicyclic polycarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 2-cyclohexanedicarboxylic acid and anhydrides thereof; aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and the like. The polycarboxylic acid may be used in an amount of 1 or2 or more.
The polycarboxylic acid preferably contains an aromatic polycarboxylic acid. Examples of the aromatic polycarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, and 2,2' -biphenyl dicarboxylic acid, and derivatives thereof (aromatic dicarboxylic acids). Examples of the carboxylic acids include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Further, tri-or more functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and an acid value to the polyester resin (A1) are also included in the aromatic polycarboxylic acids. Examples of the aromatic carboxylic acid in the three-or higher-functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3',4,4' -diphenylsulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
Among these, aromatic dicarboxylic acids are preferable, terephthalic acid and isophthalic acid are particularly preferable, and isophthalic acid is further preferable.
The content of the aromatic polycarboxylic acid based on the entire polycarboxylic acid is preferably 25 mol% or more, more preferably 40 mol% or more, particularly preferably 70 mol% or more, and further preferably 90 mol% or more. The aromatic polycarboxylic acids may occupy 100 mole%. If the content of the aromatic carboxylic acid is too small, the long-term durability in a hot and humid environment tends to be insufficient.
The content (molar ratio) of the aromatic polycarboxylic acid relative to the entire polycarboxylic acid is determined by the following formula.
Aromatic acid content (mol%) = (aromatic polycarboxylic acid (mol)/polycarboxylic acid (mol)) ×100
From the viewpoint of hygroscopicity of the polyester resin (A1), the content of the aromatic dicarboxylic acid having a sulfonate group such as sulfonic acid terephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2, 7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, and the like, and the metal salt or ammonium salt thereof, and the like, relative to the entire polycarboxylic acid, is preferably 10 mol% or less, more preferably 5 mol% or less, particularly preferably 3 mol% or less, further preferably 1 mol% or less, and most preferably 0 mol%.
[ Polyhydric alcohols ]
Examples of the polyhydric alcohol include monomers having a bisphenol skeleton, aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, and aromatic polyhydric alcohols. The polyhydric alcohol may be used in an amount of 1 or 2 or more.
Examples of the monomer having a bisphenol skeleton include bisphenol a, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4' -dihydroxybenzophenone, bisphenol fluorene, and a hydride thereof; ethylene oxide adducts and the like obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols, glycols and the like such as propylene oxide adducts and the like. Among them, bisphenol a skeleton is preferably contained, and ethylene oxide adducts are preferable from the viewpoint of reactivity, and ethylene oxide 2 to 3 mol adducts are preferable from the viewpoints of heat resistance, low hygroscopicity, and long-term durability under a humid and hot environment.
The content of the bisphenol skeleton-containing monomer relative to the entire polyhydric alcohol is preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 30 mol% or more, and further preferably 40 mol% or more. If the content of the bisphenol skeleton-containing monomer is too small, low hygroscopicity and long-term durability under a hot and humid environment tend to be insufficient.
The upper limit of the content of the monomer having a bisphenol skeleton relative to the entire polyol is 100 mol%.
Examples of the aliphatic polyhydric alcohol include ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 1, 9-nonanediol, 2-ethyl-2-butylpropanediol, dimethylolheptane, and 2, 4-trimethyl-1, 3-pentanediol.
Examples of the alicyclic polyol include 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.
Examples of the aromatic polyol include paradimethanol, isophthaloyl dimethanol, phthalic dimethanol, 1, 4-benzenediol, and ethylene oxide adducts of 1, 4-benzenediol.
The content of the ether bond-containing diol other than the bisphenol skeleton-containing monomer such as diethylene glycol, triethylene glycol, dipropylene glycol, and polyethylene glycol, polypropylene glycol, polytetramethylene glycol is preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, further preferably 8% by weight or less, and most preferably 5% by weight or less, based on the entire polyester resin, from the viewpoints of heat resistance, low hygroscopicity, and long-term durability under hot and humid environments.
[ Whole of raw material Compound constituting polyester resin (A1) ]
The compound constituting the polyester resin (A1) may contain dimer acids as polycarboxylic acids, and may contain dimer alcohols as polyalcohols, regardless of whether or not dimer acids are contained.
In the present invention, the compound constituting the polyester resin (A1) particularly preferably contains at least one selected from the group consisting of dimer acids as polycarboxylic acids and dimer alcohols as polyols.
Examples of the dimer acids and the dimer alcohols include dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like (mainly those having 36 to 44 carbon atoms), dimer alcohols which are their reduced products, and their hydrides. Among them, from the viewpoint of suppressing gelation at the time of production, a hydride is preferable, and from the viewpoint of increasing the content ratio of the aromatic acid in the polycarboxylic acid component, a dimer alcohol is preferable, and a hydrogenated dimer alcohol is particularly preferable.
The total content (α+β) (mol%) of the dimer acid based on the total content (α) of the polycarboxylic acid based on the total content (β) of the dimer alcohol based on the total content (β) of the polyhydric alcohol is preferably 5 mol% or more, more preferably 10 mol% or more, particularly preferably 15 mol% or more, and further preferably 20 mol% or more. The total content (α+β) (mol%) is preferably 100 mol% or less, more preferably 80 mol% or less, particularly preferably 65 mol% or less, and further preferably 55 mol% or less.
If the total content (α+β) (mol%) of dimer acids and dimer alcohols is too small, there is a tendency that low hygroscopicity and long-term durability under a hot and humid environment become insufficient, and if the total content (α+β) (mol%) is too large, there is a tendency that non-tackiness before curing and initial adhesiveness after curing become insufficient.
The ratio ((β)/(α+β) (molar ratio)) of the content (β) of the dimer acid to the total content (α+β) of the dimer alcohol is preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, further preferably 0.9 or more, and most preferably 1.
If the content (β) of the dimer alcohol is too small relative to the total content (α+β) of the dimer acid and the dimer alcohol, the long-term durability in a hot and humid environment tends to be insufficient.
The total content (α+β) (wt%) of the dimer acid content (α) and the dimer alcohol content (β) is preferably 10 wt% or more, more preferably 15 wt% or more, particularly preferably 20 wt% or more, further preferably 30 wt% or more, based on the entire polyester resin (A1), and the total content (α+β) (wt%) is preferably 80 wt% or less, more preferably 70 wt% or less, particularly preferably 60 wt% or less, further preferably 50 wt% or less.
If the total content (α+β) (wt%) of dimer acids and dimer alcohols is too small, there is a tendency that low hygroscopicity and long-term durability under a hot and humid environment become insufficient, and if the total content (α+β) (wt%) is too large, there is a tendency that non-tackiness before curing and adhesiveness after curing become insufficient.
In addition, a hydroxycarboxylic acid compound having a hydroxyl group and a carboxyl group in the molecular structure can also be used as a raw material compound for the polyester resin (A1). Examples of the hydroxycarboxylic acid compound include 5-hydroxyisophthalic acid, parahydroxybenzoic acid, parahydroxyphenylpropionic acid, parahydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4, 4-bis (parahydroxyphenyl) valeric acid.
In the polyester resin (A1) used in the present invention, at least one selected from the group consisting of trifunctional or higher polycarboxylic acids and trifunctional or higher polyols may be copolymerized, if necessary, for the purpose of introducing a branched skeleton, in addition to the polycarboxylic acid anhydride described later. In particular, when a cured coating film is obtained by reacting the resin with a curing agent, a coating film having an increased terminal group concentration (reaction site) of the resin, a high crosslinking density and high toughness can be obtained by introducing a branched skeleton.
Examples of the polycarboxylic acids having three or more functions include trimellitic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3', and 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like. Examples of the trifunctional or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and the like.
The trifunctional or higher polycarboxylic acid and the trifunctional or higher polyol may be used in an amount of 1 or 2 or more, respectively.
When at least one selected from the group consisting of trifunctional or higher polycarboxylic acids and trifunctional or higher polyols is used in addition to the polycarboxylic acid anhydride described later, the content of trifunctional or higher polycarboxylic acids relative to the entire polycarboxylic acid or the content of trifunctional or higher polyols relative to the entire polyols is preferably in the range of 0.1 to 5 mol%, more preferably 0.1 to 3 mol%, respectively. If the content of either or both is too large, mechanical properties such as elongation at break point of a coating film formed by applying an adhesive tend to be lowered, and gelation tends to occur during polymerization.
From the viewpoints of curing speed and heat resistance after curing, the polyester resin (A1) in the present invention preferably has a carboxyl group in a side chain. Such a polyester resin (A1) can be obtained by copolymerizing a polycarboxylic acid anhydride having a carboxylic acid anhydride structure (hereinafter, sometimes simply referred to as "polycarboxylic acid anhydride") as a copolymerization component of polycarboxylic acids.
The polycarboxylic acid anhydride preferably has at least two carboxylic acid anhydride structures for the purpose of introducing a carboxyl group into a side chain, and examples thereof include 1,2,4, 5-benzene tetracarboxylic dianhydride (pyromellitic dianhydride), 3', aromatic polycarboxylic acid anhydrides such as 4,4' -benzophenone tetracarboxylic acid dianhydride, 4-oxydiphthalic acid dianhydride, 2,3,6, 7-naphthalene tetracarboxylic acid dianhydride, 1,2,5, 6-naphthalene tetracarboxylic acid dianhydride, ethylene glycol bis-trimellitate dianhydride, 3', 4' -diphenyl tetracarboxylic acid dianhydride, 2', 3' -diphenyl sulfone tetracarboxylic acid anhydride, thiophene-2, 3,4, 5-tetracarboxylic acid dianhydride, and the like;
Alicyclic polycarboxylic acid anhydrides such as 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 5- (2, 5-dioxotetrahydrofuranyl) -3-methyl-3-cyclohexene-1, 2-dicarboxylic anhydride, 5- (2, 5-dioxotetrahydrofuranyl) -3-cyclohexene-1, 2-dicarboxylic anhydride, and cyclopentane tetracarboxylic dianhydride;
Aliphatic polycarboxylic acid anhydrides such as ethylene tetracarboxylic dianhydride, 1,2,3, 4-butane tetracarboxylic dianhydride, and 1,2,3, 4-pentane tetracarboxylic dianhydride; etc. 1 kind selected from them may be used alone, or 2 or more kinds may be used in combination.
Among these polycarboxylic acid anhydrides, aromatic polycarboxylic acid anhydrides are preferable, 1,2,4, 5-benzene tetracarboxylic acid dianhydride (pyromellitic dianhydride), 2,3,6, 7-naphthalene tetracarboxylic acid dianhydride, 1,2,5, 6-naphthalene tetracarboxylic acid dianhydride, 3', 4' -diphenyl tetracarboxylic acid dianhydride, and particularly 1,2,4, 5-benzene tetracarboxylic acid dianhydride (pyromellitic dianhydride) from the viewpoints of polymerization reactivity at the time of producing the polyester resin (A1), heat resistance of the produced polyester resin (A1), and long-term durability under a hot and humid environment.
The content of the polycarboxylic acid anhydride in the polycarboxylic acid is preferably 0.5 to 20 mol%, more preferably 1 to 15 mol%, particularly preferably 2 to 10 mol%, further preferably 3 to 8 mol% based on the whole polycarboxylic acid. If the content is too small, the heat resistance tends to be insufficient, and if the content is too large, gelation occurs in the production process of the polyester resin (A1), or low hygroscopicity and long-term durability under a hot and humid environment tend to be insufficient.
[ Production of polyester resin (A1) ]
The polyester resin (A1) used in the present invention can be produced by a known method, for example, by esterifying a polycarboxylic acid with a polyhydric alcohol in the presence of a catalyst if necessary to obtain a polyester resin, and introducing an acid value.
Examples of the method for introducing an acid value into a polyester resin include a method for introducing a carboxylic acid into a resin by acid addition after an esterification reaction and a reduced pressure polycondensation. If monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compounds are used for the acid addition, the molecular weight may be reduced by transesterification, and preferably, a compound having at least one carboxylic anhydride is used. Examples of the acid anhydride include succinic anhydride, maleic anhydride, phthalic anhydride, 2, 5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3', and 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
If the total amount of the polycarboxylic acids constituting the polyester resin (A1) is 100 mol%, gelation may occur when 15 mol% or more of the acid is added, and depolymerization of the polyester may occur to reduce the molecular weight of the resin. Examples of the method of acid addition include a method of direct addition in a bulk (bulk) state and a method of adding a polyester in a solution. Although the reaction rate is high in the bulk state, gelation may occur in the case of addition in a large amount, and the reaction may be performed at a high temperature, and therefore, attention must be paid to blocking oxygen to prevent oxidation or the like. On the other hand, although the addition reaction in the solution state is slow, a large amount of carboxyl groups can be stably introduced.
In addition, when a polyester resin having a carboxyl group in a side chain is obtained, a method of reacting a polycarboxylic acid anhydride with a hydroxyl group-containing prepolymer obtained by copolymerizing a polycarboxylic acid other than the polycarboxylic acid anhydride with a polyhydric alcohol is preferable from the viewpoint of productivity.
[ Concentration of ester bond in polyester resin (A1) ]
The concentration of the ester bond in the polyester resin (A1) used in the present invention is 7 mmol/g or less, preferably 2 to 6.5 mmol/g, more preferably 2.5 to 6 mmol/g, particularly preferably 3 to 5.5 mmol/g, and further preferably 3.1 to 5 mmol/g.
If the ester bond concentration is too high, low hygroscopicity and long-term durability under a hot and humid environment become insufficient. In addition, if the concentration of the ester bond is too low, initial adhesion becomes insufficient.
The definition and measurement method of the ester bond concentration are as follows.
The ester bond concentration (mmol/g) is the number of moles of ester bonds in 1g of the polyester resin, and is calculated, for example, from the calculated value derived from the amount of the polyester resin fed. The calculation method is a value obtained by dividing the number of moles of the smaller one of the amounts of polycarboxylic acids and polyols by the total weight of the resin, and an example of the calculation formula is shown below.
The amounts of the polycarboxylic acids and the polyhydric alcohols to be added are the same in terms of the molar amounts. Any of the following formulas may be used.
In addition, when a substance having both a carboxyl group and a hydroxyl group, or when a polyester is produced from caprolactone or the like is used as a monomer, the calculation method is appropriately changed.
(The polycarboxylic acid is less than the polyhydric alcohol)
Concentration of ester group (mmol/g) = [ (A1/a1×m1+A2/a2×m2+A3/a3×m3 …)/Z ] ×1000
A: charge amount (g) of polycarboxylic acid
A: molecular weight of polycarboxylic acids
M: number of carboxylic acid groups per 1 molecule of polycarboxylic acid
Z: weight of finished product (g)
(Where polyols are less than polycarboxylic acids)
Concentration of ester group (mmol/g) = [ (B1/b1×n1+B2/b2×n2+B3/b3×n3 …)/Z ] ×1000
B: amount of polyol (g)
B: molecular weight of polyol
N: number of hydroxyl groups per 1 molecule of polyol
Z: weight of finished product (g)
The ester bond concentration may be measured by a known method using NMR or the like.
In addition, from the viewpoint of low hygroscopicity and long-term durability under a hot and humid environment, it is preferable that the concentration of the other polar groups other than the ester bond and the reactive functional group is low.
Examples of the other polar group include an amide group, an imide group, a urethane group, an urea group, an ether group, and a carbonate group.
The total concentration of the amide groups, imide groups, urethane groups and urea groups is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
Examples of the ether group include an alkyl ether group and a phenyl ether group, and particularly, it is preferable to reduce the concentration of the alkyl ether group from the viewpoints of low hygroscopicity and long-term durability under a hot and humid environment.
The concentration of the alkyl ether group is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1.5 mmol/g or less, further preferably 1 mmol/g or less, and most preferably 0.5 mmol/g or less. The concentration of the phenyl ether group is preferably 5 mmol/g or less, more preferably 4 mmol/g or less, particularly preferably 3 mmol/g or less, and further preferably 2.5 mmol/g or less.
The carbonate group concentration is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
[ Acid value of polyester resin (A1) ]
The acid value of the polyester resin (A1) used in the present invention is 3mgKOH/g or more, preferably 4 to 60mgKOH/g, more preferably 5 to 40mgKOH/g, particularly preferably 6 to 30mgKOH/g, and further preferably 7 to 20mgKOH/g.
When the acid value is too low, the crosslinking site between the adhesive composition and the polyepoxide compound (B) becomes insufficient, and the degree of crosslinking becomes low, so that the heat resistance becomes insufficient. In addition, when the acid value is too high, hygroscopicity, long-term durability under a hot and humid environment are lowered, or a large amount of the polyepoxide compound (B) is required at the time of curing, so that an increase in dielectric characteristics is required in recent years, and tends to be deteriorated.
The definition and measurement method of the acid value are as follows.
The acid value (mgKOH/g) can be obtained by dissolving 1g of the polyester resin in 30g of a mixed solvent of toluene/methanol (for example, toluene/methanol=7/3 by volume ratio) and performing neutralization titration according to JIS K0070.
In the present invention, the acid value of the polyester resin (A1) is due to the carboxyl group content in the resin.
[ Glass transition temperature (Tg) of polyester resin (A1) ]
The glass transition temperature (Tg) of the polyester resin (A1) used in the present invention is-5℃or higher, preferably 0 to 100℃and more preferably 3 to 80℃and even more preferably 5 to 60℃and even more preferably 7 to 40℃and most preferably 10 to 30 ℃.
If the glass transition temperature (Tg) is too low, initial adhesion and non-tackiness become insufficient. If the glass transition temperature (Tg) is too high, initial adhesion and bendability tend to be insufficient.
The method for measuring the glass transition temperature (Tg) is as follows.
The glass transition temperature (Tg) can be determined by measurement using a differential scanning calorimeter. The measurement conditions were as follows: the measurement temperature ranges from-70 ℃ to 140 ℃ and the temperature rising speed is 10 ℃/min.
[ Peak top molecular weight (Mp) and weight average molecular weight (Mw) ] of the polyester-based resin (A1)
The peak top molecular weight (Mp) of the polyester resin (A1) used in the present invention is preferably 5000 to 150000, more preferably 10000 to 100000, particularly preferably 15000 to 70000, and further preferably 25000 to 40000.
If the peak top molecular weight (Mp) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the peak top molecular weight (Mp) is too high, the following tends to occur: the initial adhesion becomes insufficient, or the solution viscosity at the time of coating becomes too high, and it becomes difficult to obtain a uniform coating film.
The weight average molecular weight (Mw) of the polyester resin (A1) used in the present invention is preferably 5000 to 300000, more preferably 10000 to 200000, particularly preferably 20000 to 150000, further preferably 30000 to 100000.
If the weight average molecular weight (Mw) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the weight average molecular weight (Mw) is too high, the following tends to occur: the initial adhesiveness becomes insufficient; or the solution viscosity at the time of coating is too high, and it is difficult to obtain a uniform coating film.
The measurement methods of the peak top molecular weight (Mp) and the weight average molecular weight (Mw) are as follows.
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) can be determined as follows: the molecular weight was measured by a high performance liquid chromatograph (manufactured by Tosoh corporation, "HLC-8320 GPC") using two columns (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2X 10 6, theoretical plate number: 16000 grade/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm)) in series, and the molecular weight was converted to standard polystyrene.
[ Water absorption (wt.%) ] of the polyester resin (A1)
The water absorption of the polyester resin (A1) used in the present invention is preferably 2 wt% or less, more preferably 1 wt% or less, particularly preferably 0.8 wt% or less, and further preferably 0.6 wt% or less.
If the water absorption is too high, the wet heat durability, insulation reliability and dielectric characteristics tend to be poor. The difference in dielectric characteristics means that: the relative dielectric constant and the dielectric loss tangent do not decrease or increase.
The method for measuring the water absorption is as follows.
The polyester resin solution (before compounding the polyepoxide compound (B)) was applied to a release film by an applicator and dried at 120 ℃ for 10 minutes to prepare a sheet having a polyester resin layer with a dry film thickness of 65 μm. The sheet was cut into a size of 7.5cm×11cm, and the polyester resin layer of the sheet was laminated on a glass plate, and then the release film was peeled off. This operation was repeated 6 times to obtain a test sheet having a polyester resin layer with a thickness of 390 μm on a glass plate.
The test plate thus obtained was immersed in purified water at 23℃for 24 hours, and then the surface was taken out and wiped off with moisture, and dried at 70℃for 2 hours. The required weight was measured in each of these steps, and the water absorption (wt%) was calculated from the weight change according to the following formula.
(c-d)×100/(b-a)
A: weight of glass sheets alone
B: weight of initial test plate
C: weight of test plate immediately after removal of water from purified water
D: weight of the test plate after drying at 70℃for 2 hours
The content of the polyester resin (A1) in the polyester resin in the adhesive composition of the present invention is preferably more than 50% by weight, more preferably 70% by weight or more, particularly preferably 85% by weight or more of the entire polyester resin. If the content is too small, the hygroscopicity tends to be low and the long-term durability in a hot and humid environment tends to be insufficient.
< Polyepoxide Compound (B) >)
The adhesive composition of the present invention preferably further contains a polyepoxide compound (B). By reacting the epoxy group in the polyepoxide compound (B) with the carboxyl group in the polyester resin (A1) to cure the same, an adhesive layer excellent in heat resistance, adhesion and solder heat resistance can be obtained.
Examples of the polyepoxide compound (B) used in the present invention include difunctional glycidyl ethers such as bisphenol a diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol a diglycidyl ether; a multifunctional glycidyl ether type such as phenol novolac glycidyl ether and cresol novolac glycidyl ether; glycidyl ester types such as glycidyl hexahydrophthalate and glycidyl dimer acid; triglycidyl isocyanurate, 3, 4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil and other alicyclic or aliphatic epoxides, and the like. The polyepoxide compound (B) may be used in an amount of 1 or 2 or more.
In the adhesive composition of the present invention, when the polyepoxide compound (B) contains a polyepoxide compound containing a nitrogen atom (polyepoxide compound containing a nitrogen atom), the following tends to be present: the coating film of the adhesive composition can be B-stageable (semi-solid state) by heating at a relatively low temperature, and the fluidity of the B-stageable film can be suppressed to improve workability in the bonding operation. In addition, the effect of suppressing the foaming of the B-stage film can be expected, and is preferable.
Examples of the nitrogen atom-containing polyepoxide compound include glycidyl amines such as tetraglycidyl diaminodiphenylmethane, triglycidyl para-aminophenol, tetraglycidyl bisaminomethyl cyclohexanone, and N, N' -tetraglycidyl meta-xylylenediamine.
The adhesive composition of the present invention contains the polyepoxide compound (B), and when the polyepoxide compound (B) contains these polyepoxide compounds having nitrogen atoms, the content of the polyepoxide compound having nitrogen atoms is preferably 30% by weight or less, more preferably 25% by weight or less, particularly preferably 20% by weight or less, relative to the entire polyepoxide compound (B).
The content of the nitrogen atom-containing polyepoxide compound is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight or less based on 100 parts by weight of the polyester resin (A1).
If the content of the nitrogen atom-containing polyepoxide compound is too large, the rigidity tends to be excessively high and the adhesiveness tends to be lowered, and the crosslinking reaction tends to occur during the storage of the adhesive sheet and the sheet life tends to be lowered.
The equivalent weight of the epoxy group to the carboxyl group is preferably 0.8 to 5, more preferably 0.9 to 3, particularly preferably 1 to 2.5, and further preferably 1.2 to 2.
If the equivalent amount is too large, initial adhesion and low hygroscopicity tend to be insufficient or dielectric characteristics tend to be poor. If too small, the long-term durability and solder heat resistance in a hot and humid environment tend to be insufficient.
The equivalent weight of the epoxy group to the carboxyl group (COOH) is determined from the acid value of the polyester resin (A1) and the epoxy equivalent weight (g/eq) of the polyepoxide compound (B) to be compounded.
Equivalent of epoxy group to cooh= (a/WPE)/(AV/56.1/1000×b)
A: weight (g) of polyepoxide compound (B) used in the compounding
WPE: epoxy equivalent (g/eq) of polyepoxide (B)
AV: acid value (mgKOH/g) of polyester resin (A1)
B: weight (g) of polyester resin (A1) used in compounding
< Adhesive composition >
The adhesive composition of the present invention contains at least a polyester resin (A1), preferably a polyepoxide compound (B), and has the effects of low hygroscopicity, non-tackiness before curing, initial adhesiveness after curing, and excellent long-term durability under a hot and humid environment.
In the adhesive composition of the present invention, a filler, a flame retardant, and the like may be blended, and in this case, the content of the polyester resin (A1) in the adhesive composition is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, and further preferably 60 to 85% by weight, based on the entire solid content, in consideration of the filler, the flame retardant, and the like.
When the adhesive composition of the present invention contains the polyepoxide compound (B), the content of the polyepoxide compound (B) is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight, and further preferably 4 to 10 parts by weight, relative to 100 parts by weight of the polyester resin (A1). If the content of the polyepoxide compound (B) is too small, heat resistance and long-term durability in a hot and humid environment tend to be insufficient, and if it is too large, initial adhesion and low hygroscopicity tend to be insufficient or dielectric characteristics tend to be poor.
The adhesive composition of the present invention may be blended with a solvent in order to appropriately adjust the viscosity of the adhesive composition and to facilitate handling in forming a coating film. The solvent is used for ensuring handling and workability in molding the adhesive composition, and the amount thereof is not particularly limited.
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; aromatic compounds such as toluene and xylene. The above-listed solvents may be used in an amount of 1, or may be used in an amount of 2 or more in any combination and ratio.
[ Other ingredients ]
The adhesive composition of the present invention may contain other components than those listed above for the purpose of further improving the functionality thereof. Examples of the other components include inorganic fillers, coupling agents such as silane coupling agents, ultraviolet screening agents, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, low-elasticity agents, diluents, antifoaming agents, ion capturing agents, leveling agents, catalysts, and the like.
When the adhesive composition of the present invention contains other components, the content of the other components is preferably 70% by weight or less, more preferably 0.05 to 60% by weight, particularly preferably 0.1 to 50% by weight, and further preferably 0.2 to 40% by weight.
< Adhesive >
The adhesive of the present invention is obtained by curing the adhesive composition, and has the effects of excellent initial adhesion, low hygroscopicity, and long-term durability in a hot and humid environment.
The term "curing" as used herein means that the adhesive composition is intentionally cured by heat and/or light or the like, and the degree of curing can be controlled according to desired physical properties and uses. The degree of curing can be confirmed by the gel fraction of the adhesive, and the gel fraction is preferably 50% or more, more preferably 60% or more, particularly preferably 70% or more, and further preferably 75% or more. If the gel fraction is too low, heat resistance and long-term durability under a hot and humid environment tend to be insufficient.
The gel fraction refers to: the adhesive was immersed in methyl ethyl ketone at 23 ℃ for 24 hours, and the weight of the insoluble adhesive component was relative to the weight of the adhesive before immersion.
The method for curing the adhesive composition of the present invention when the adhesive composition is cured or semi-cured to prepare an adhesive may vary depending on the compounding ingredients and the compounding amount in the adhesive composition, and generally, heating conditions of 80 to 200℃and 10 minutes to 10 hours are exemplified.
When the adhesive composition of the present invention is cured using the polyepoxide compound (B), a catalyst may be used.
Examples of such a catalyst 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) -undec-7-ene, 1, 5-diazabicyclo (4, 3, 0) -nonen-5, 6-dibutylamino-1, 8-diazabicyclo (5, 4, 0) -undec-7-ene; compounds obtained by preparing amine salts from these tertiary amines such as phenol, octanoic acid, and quaternized tetraphenyl borate; cationic catalysts such as triallyl sulfonium hexafluoroantimonate and diallyl iodonium hexafluoroantimonate; triphenylphosphine, and the like. Among these, tertiary amines such as1, 8-diazabicyclo (5, 4, 0) -undec-7-ene, 1, 5-diazabicyclo (4, 3, 0) -5-nonene, 6-dibutylamino-1, 8-diazabicyclo (5, 4, 0) -undec-7-ene and the like are preferable from the viewpoints of thermosetting property and heat resistance, adhesion to metals, and storage stability after compounding; and compounds obtained by preparing amine salts from these tertiary amines such as phenol, octanoic acid, and quaternized tetraphenyl borate salts.
The blending amount in this case is preferably 0.01 to 1 part by weight based on 100 parts by weight of the polyester resin (A1). If the amount is within this range, the catalytic effect for the reaction of the polyester resin (A1) and the polyepoxide compound (B) is further increased, and a strong adhesive property can be obtained.
[ Use ]
The adhesive of the present invention is effective for bonding a substrate made of various materials such as resin and metal, and is particularly suitable for an adhesive used for producing a laminate of a metal layer and a plastic layer, for example, an adhesive used for bonding an electronic material member, because it is excellent in initial adhesion, low hygroscopicity, and long-term durability under a hot and humid environment.
Examples of the "electronic material member" in the present invention include a flexible printed board, a cover layer, and a bonding sheet.
Examples of the product produced by bonding the electronic material members include flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. The flexible laminate is a laminate obtained by stacking, for example, "flexible substrate having flexibility/adhesive layer/conductive metal layer made of copper, aluminum, an alloy thereof, or the like" in this order, and the adhesive of the present invention can be used as an adhesive constituting the adhesive layer. 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.
Second mode
The adhesive composition of the present invention contains at least a polyester resin (A2), wherein the polyester resin (A2) contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol. First, the polyester resin (A2) will be described.
< Polyester resin (A2) >)
The polyester resin (A2) preferably contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and is a resin obtained by bonding a polycarboxylic acid and a polyhydric alcohol by an ester bond.
[ Polycarboxylic acids ]
Examples of the polycarboxylic acid include aromatic polycarboxylic acids described below; a 3-or more-membered polycarboxylic acid (x 1) having 0 or 1 acid anhydride group; alicyclic polycarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, and 1, 2-cyclohexanedicarboxylic acid and anhydrides thereof; aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and the like. The polycarboxylic acid may be used in an amount of 1 or 2 or more.
The polycarboxylic acids contain aromatic polycarboxylic acids. Examples of the aromatic polycarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, and the like, and derivatives thereof (aromatic dicarboxylic acids). Examples of the carboxylic acids include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Further, tri-or more functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and an acid value to the polyester resin (A2) are also included in the aromatic polycarboxylic acids. Examples of the aromatic carboxylic acid in the three-or higher-functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3',4,4' -diphenylsulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
Among these, aromatic dicarboxylic acids are preferable, terephthalic acid and isophthalic acid are particularly preferable, and isophthalic acid is further preferable.
The content of the aromatic polycarboxylic acid is 25 mol% or more, preferably 40 mol% or more, more preferably 70 mol% or more, particularly preferably 90 mol% or more, based on the entire polycarboxylic acid. The aromatic polycarboxylic acids may occupy 100 mole%. If the content of the aromatic carboxylic acid is too small, the long-term durability in a hot and humid environment becomes insufficient.
The content (molar ratio) of the aromatic polycarboxylic acid relative to the entire polycarboxylic acid is determined by the following formula.
Aromatic acid content (mol%) = (aromatic polycarboxylic acid (mol)/polycarboxylic acid (mol)) ×100
The polycarboxylic acid further contains a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group. The valence of the carboxyl group in the polycarboxylic acid (x 1) is preferably 3 to 6, more preferably 3 to 4. Examples of the polycarboxylic acid (x 1) include those having 0 or 1 acid anhydride group in the above trifunctional or higher aromatic carboxylic acids. Examples of the acid anhydride include trimellitic anhydride, trimellitic acid, and among these, the number of acid anhydride groups is preferably 1, and trimellitic anhydride is particularly preferred.
Examples of the polycarboxylic acid (x 1) other than the aromatic carboxylic acid include hydrogenated trimellitic anhydride and the like.
From the viewpoint of hygroscopicity of the polyester resin (A2), the content of the aromatic dicarboxylic acid having a sulfonate group such as sulfonic acid terephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2, 7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, and the like, and the metal salt or ammonium salt thereof, and the like, relative to the entire polycarboxylic acid, is preferably 10 mol% or less, more preferably 5 mol% or less, particularly preferably 3 mol% or less, further preferably 1 mol% or less, and most preferably 0 mol%.
[ Polyhydric alcohols ]
The polyhydric alcohol is the same as the polyhydric alcohol described in the first embodiment. That is, examples thereof include monomers having a bisphenol skeleton, aliphatic polyols, alicyclic polyols, and aromatic polyols. The polyhydric alcohol may be used in an amount of 1 or 2 or more.
Examples of the monomer having a bisphenol skeleton include bisphenol a, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4' -dihydroxybenzophenone, bisphenol fluorene, and a hydride thereof; ethylene oxide adducts and the like obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols, glycols and the like such as propylene oxide adducts and the like. Among them, bisphenol a skeleton is preferably contained, and ethylene oxide adducts are preferable from the viewpoint of reactivity, and ethylene oxide 2 to 3 mol adducts are preferable from the viewpoints of heat resistance, low hygroscopicity, and long-term durability under a humid and hot environment.
The content of the bisphenol skeleton-containing monomer relative to the entire polyhydric alcohol is preferably 10 mol% or more, more preferably 20 mol% or more, particularly preferably 30 mol% or more, and further preferably 40 mol% or more. If the content of the bisphenol skeleton-containing monomer is too small, low hygroscopicity and long-term durability under a hot and humid environment tend to be insufficient.
The upper limit of the content of the monomer having a bisphenol skeleton relative to the entire polyol is 100 mol%.
Examples of the aliphatic polyhydric alcohol include ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 1, 9-nonanediol, 2-ethyl-2-butylpropanediol, dimethylolheptane, and 2, 4-trimethyl-1, 3-pentanediol.
Examples of the alicyclic polyol include 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.
Examples of the aromatic polyol include paradimethanol, isophthaloyl dimethanol, phthalic dimethanol, 1, 4-benzenediol, and ethylene oxide adducts of 1, 4-benzenediol.
The content of the ether bond-containing diol other than the bisphenol skeleton-containing monomer such as diethylene glycol, triethylene glycol, dipropylene glycol, and polyethylene glycol, polypropylene glycol, polytetramethylene glycol is preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, further preferably 8% by weight or less, and most preferably 5% by weight or less, based on the entire polyester resin, from the viewpoints of heat resistance, low hygroscopicity, and long-term durability under hot and humid environments.
[ Whole of raw material Compound constituting polyester resin (A2) ]
The compound constituting the polyester resin (A2) may contain dimer acids as polycarboxylic acids, and may contain dimer alcohols as polyalcohols, regardless of whether or not dimer acids are contained.
The dimer acids and the dimer alcohols are the same as those described in the first embodiment. That is, in the present invention, the compound constituting the polyester resin (A2) particularly preferably contains at least one selected from the group consisting of dimer acids as polycarboxylic acids and dimer alcohols as polyalcohols.
Examples of the dimer acids and the dimer alcohols include dimer acids derived from oleic acid, linoleic acid, linolenic acid, erucic acid and the like (mainly those having 36 to 44 carbon atoms), dimer alcohols which are their reduced products, and their hydrides. Among them, from the viewpoint of suppressing gelation at the time of production, a hydride is preferable, and from the viewpoint of increasing the content ratio of the aromatic acid in the polycarboxylic acid component, a dimer alcohol is preferable, and a hydrogenated dimer alcohol is particularly preferable.
The total content (α+β) (mol%) of the dimer acid based on the total content (α) of the polycarboxylic acid based on the total content (β) of the dimer alcohol based on the total content (β) of the polyhydric alcohol is preferably 5 mol% or more, more preferably 10 mol% or more, particularly preferably 15 mol% or more, and further preferably 20 mol% or more. The total content (α+β) (mol%) is preferably 100 mol% or less, more preferably 80 mol% or less, particularly preferably 65 mol% or less, and further preferably 55 mol% or less.
If the total content (α+β) (mol%) of dimer acids and dimer alcohols is too small, there is a tendency that low hygroscopicity and long-term durability under a hot and humid environment become insufficient, and if the total content (α+β) (mol%) is too large, there is a tendency that non-tackiness before curing and initial adhesiveness after curing become insufficient.
The ratio ((β)/(α+β) (molar ratio)) of the content (β) of the dimer acid to the total content (α+β) of the dimer alcohol is preferably 0.6 or more, more preferably 0.7 or more, particularly preferably 0.8 or more, further preferably 0.9 or more, and most preferably 1.
If the content (β) of the dimer alcohol is too small relative to the total content (α+β) of the dimer acid and the dimer alcohol, the long-term durability in a hot and humid environment tends to be insufficient.
The total content (α+β) (wt%) of the dimer acid content (α) and the dimer alcohol content (β) is preferably 10 wt% or more, more preferably 15 wt% or more, particularly preferably 20 wt% or more, further preferably 30 wt% or more, based on the entire polyester resin (A2), and the total content (α+β) (wt%) is preferably 80 wt% or less, more preferably 70 wt% or less, particularly preferably 60 wt% or less, further preferably 50 wt% or less.
If the total content (α+β) (wt%) of dimer acids and dimer alcohols is too small, the low hygroscopicity tends to be insufficient, and the long-term durability under a hot and humid environment tends to be insufficient, and if the total content (α+β) (wt%) is too large, the adhesiveness tends to be insufficient.
In addition, a hydroxycarboxylic acid compound having a hydroxyl group and a carboxyl group in the molecular structure can also be used as a raw material compound for the polyester resin (A2). Examples of the hydroxycarboxylic acid compound include 5-hydroxyisophthalic acid, parahydroxybenzoic acid, parahydroxyphenylpropionic acid, parahydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4, 4-bis (parahydroxyphenyl) valeric acid.
In the polyester resin (A2) used in the present invention, in addition to the polycarboxylic acid (x 1) used in the depolymerization reaction described later, at least one selected from the group consisting of a trifunctional or higher polycarboxylic acid and a trifunctional or higher polyol is preferably copolymerized for the purpose of introducing a branched skeleton. In particular, when a cured coating film is obtained by reacting the resin with a curing agent, a coating film having an increased terminal group concentration (reaction site) of the resin, a high crosslinking density and high toughness can be obtained by introducing a branched skeleton.
Examples of the polycarboxylic acids having three or more functions include trimellitic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3', and 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like. Examples of the trifunctional or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and the like.
The trifunctional or higher polycarboxylic acid and the trifunctional or higher polyol may be used in an amount of 1 or 2 or more, respectively.
When at least one selected from the group consisting of tri-or higher polycarboxylic acids and tri-or higher polyols is used for the purpose of introducing a branched skeleton, in addition to the polycarboxylic acids (x 1) used in the depolymerization reaction described later, the content of tri-or higher polycarboxylic acids relative to the whole polycarboxylic acids or the content of tri-or higher polyols relative to the whole polyols is preferably in the range of 0.1 to 5 mol%, more preferably 0.3 to 3 mol%, still more preferably 0.5 to 2 mol%, respectively. If the content of either or both of the components is too large, mechanical properties such as elongation at break point of a coating film formed by applying the adhesive tend to be lowered, and the adhesive strength tends to be lowered, and gelation tends to occur during polymerization.
[ Production of polyester-based resin (A2) ]
The polyester resin (A2) used in the present invention can be produced by a known method, for example, by esterifying a polycarboxylic acid with a polyhydric alcohol in the presence of a catalyst as needed to obtain a prepolymer, then polycondensing the prepolymer, and further depolymerizing the prepolymer.
The temperature in the esterification reaction of the polycarboxylic acids with the polyols is generally 180 to 280℃and the reaction time is generally 60 minutes to 8 hours.
The temperature in polycondensation is generally 220 to 280℃and the reaction time is generally 20 minutes to 4 hours. In addition, the polycondensation is preferably carried out under reduced pressure.
The depolymerization is preferably carried out using a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group. Examples of the polycarboxylic acids (x 1) having 3 or more acid anhydride groups of 0 or 1 include compounds such as trimellitic acid, trimellitic anhydride, hydrogenated trimellitic anhydride, and trimesic acid. The polycarboxylic acid (x 1) having 3 or more acid anhydride groups of 1 is preferable, and examples thereof include trimellitic anhydride and hydrogenated trimellitic anhydride, and trimellitic anhydride is particularly preferable.
The temperature in depolymerization is usually 200 to 260℃and the reaction time is usually 10 minutes to 3 hours.
When the total of the polycarboxylic acids constituting the polyester resin (A2) is 100 mol%, if the polycarboxylic acids (x 1) are used in an amount of 20 mol% or more for depolymerization, the molecular weight of the resin may be significantly reduced. Therefore, when the total amount of the polycarboxylic acids constituting the polyester resin (A2) is 100 mol%, the polycarboxylic acids (x 1) are preferably used in an amount of less than 20 mol%, more preferably 1 to 15 mol%, particularly preferably 2 to 10 mol%, and still more preferably 3 to 8 mol%, to depolymerize the polyester resin.
[ Concentration of ester bond in polyester resin (A2) ]
The concentration of the ester bond of the polyester resin (A2) used in the present invention is the same as that described in the first embodiment. That is, the concentration is 7 mmol/g or less, preferably 2 to 6.5 mmol/g, more preferably 2.5 to 6 mmol/g, particularly preferably 3 to 5.5 mmol/g, and even more preferably 3.1 to 5 mmol/g.
If the ester bond concentration is too high, low hygroscopicity and long-term durability under a hot and humid environment become insufficient. In addition, if the concentration of the ester bond is too low, initial adhesion becomes insufficient.
The definition and measurement method of the ester bond concentration are as follows.
The ester bond concentration (mmol/g) is the number of moles of ester bonds in 1g of the polyester resin, and is calculated, for example, from the calculated value derived from the amount of the polyester resin fed. The calculation method is a value obtained by dividing the number of moles of the smaller one of the amounts of polycarboxylic acids and polyols by the total weight of the resin, and an example of the calculation formula is shown below.
The amounts of the polycarboxylic acids and the polyhydric alcohols to be added are the same in terms of the molar amounts. Any of the following formulas may be used.
In addition, when a substance having both a carboxyl group and a hydroxyl group, or when a polyester is produced from caprolactone or the like is used as a monomer, the calculation method is appropriately changed.
(The polycarboxylic acid is less than the polyhydric alcohol)
Concentration of ester group (mmol/g) = [ (A1/a1×m1+A2/a2×m2+A3/a3×m3 …)/Z ] ×1000
A: charge amount (g) of polycarboxylic acid
A: molecular weight of polycarboxylic acids
M: number of carboxylic acid groups per 1 molecule of polycarboxylic acid
Z: weight of finished product (g)
(Where polyols are less than polycarboxylic acids)
Concentration of ester group (mmol/g) = [ (B1/b1×n1+B2/b2×n2+B3/b3×n3 …)/Z ] ×1000
B: amount of polyol (g)
B: molecular weight of polyol
N: number of hydroxyl groups per 1 molecule of polyol
Z: weight of finished product (g)
The ester bond concentration may be measured by a known method using NMR or the like.
In addition, from the viewpoint of low hygroscopicity and long-term durability under a hot and humid environment, it is preferable that the concentration of the other polar groups other than the ester bond and the reactive functional group is low.
Examples of the other polar group include an amide group, an imide group, a urethane group, an urea group, an ether group, and a carbonate group.
The total concentration of the amide groups, imide groups, urethane groups and urea groups is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
Examples of the ether group include an alkyl ether group and a phenyl ether group, and particularly, it is preferable to reduce the concentration of the alkyl ether group from the viewpoints of low hygroscopicity and long-term durability under a hot and humid environment. The concentration of the alkyl ether group is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1.5 mmol/g or less, further preferably 1 mmol/g or less, and most preferably 0.5 mmol/g or less. The concentration of the phenyl ether group is preferably 5 mmol/g or less, more preferably 4 mmol/g or less, particularly preferably 3 mmol/g or less, and further preferably 2.5 mmol/g or less.
The carbonate group concentration is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
[ Acid value of polyester resin (A2) ]
The acid value of the polyester resin (A2) used in the present invention is the same as that described in the first embodiment. That is, it is 3mgKOH/g or more, preferably 4 to 60mgKOH/g, more preferably 5 to 40mgKOH/g, particularly preferably 6 to 30mgKOH/g, further preferably 7 to 20mgKOH/g.
When the acid value is too low, the crosslinking site between the adhesive composition and the polyepoxide compound (B) becomes insufficient, and the degree of crosslinking becomes low, so that the heat resistance becomes insufficient. In addition, if the acid value is too high, hygroscopicity, long-term durability under a hot and humid environment are lowered, or a large amount of the polyepoxide compound (B) is required at the time of curing, so that it tends to be difficult to obtain low dielectric characteristics which have been demanded to be increased in recent years.
The definition and measurement method of the acid value are as follows.
The acid value (mgKOH/g) can be obtained by dissolving 1g of the polyester resin in 30g of a mixed solvent of toluene/methanol (for example, toluene/methanol=7/3 by volume ratio) and performing neutralization titration according to JIS K0070.
In the present invention, the acid value of the polyester resin (A2) is due to the carboxyl group content in the resin.
[ Glass transition temperature (Tg) of polyester resin (A2) ]
The glass transition temperature (Tg) of the polyester resin (A2) used in the present invention is preferably-5℃or higher, more preferably 0 to 100℃and particularly preferably 3 to 80℃and further preferably 5 to 60℃and particularly preferably 7 to 40℃and most preferably 10 to 30 ℃.
If the glass transition temperature (Tg) is too low, initial adhesion and non-tackiness tend to be insufficient. If the glass transition temperature (Tg) is too high, initial adhesion and bendability tend to be insufficient.
The method for measuring the glass transition temperature (Tg) is as follows.
The glass transition temperature (Tg) can be determined by measurement using a differential scanning calorimeter. The measurement conditions were as follows: the measurement temperature ranges from-70 ℃ to 140 ℃ and the temperature rising speed is 10 ℃/min.
[ Peak top molecular weight (Mp) and weight average molecular weight (Mw) ] of the polyester-based resin (A2)
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) of the polyester resin (A2) used in the present invention are the same as those of the first embodiment described above. That is, the peak top molecular weight (Mp) of the polyester resin (A2) is preferably 5000 to 150000, more preferably 10000 to 100000, particularly preferably 15000 to 70000, and further preferably 25000 to 40000.
If the peak top molecular weight (Mp) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the peak top molecular weight (Mp) is too high, the following tends to occur: the initial adhesiveness becomes insufficient; or the solution viscosity at the time of coating is too high, and it is difficult to obtain a uniform coating film.
The weight average molecular weight (Mw) of the polyester resin (A2) used in the present invention is preferably 5000 to 300000, more preferably 10000 to 200000, particularly preferably 20000 to 150000, further preferably 30000 to 100000.
If the weight average molecular weight (Mw) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the weight average molecular weight (Mw) is too high, the following tends to occur: the initial adhesiveness becomes insufficient; or the solution viscosity at the time of coating is too high, and it is difficult to obtain a uniform coating film.
The measurement methods of the peak top molecular weight (Mp) and the weight average molecular weight (Mw) are as follows.
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) can be determined as follows: the molecular weight was measured by a high performance liquid chromatograph (manufactured by Tosoh corporation, "HLC-8320 GPC"), and two columns (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2X 10 6, theoretical plate number: 16000 grade/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm)) were used in series, and the result was obtained by conversion from standard polystyrene molecular weight.
[ Water absorption (wt.%) (polyester resin (A2))
The water absorption of the polyester resin (A2) used in the present invention is the same as that described in the first embodiment. That is, it is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, and further preferably 0.6% by weight or less.
If the water absorption is too high, the wet heat durability, insulation reliability and dielectric characteristics tend to be poor.
The method for measuring the water absorption is as follows.
The polyester resin solution (before compounding the polyepoxide compound (B)) was applied to a release film by an applicator and dried at 120 ℃ for 10 minutes to prepare a sheet having a polyester resin layer with a dry film thickness of 65 μm. The sheet was cut into a size of 7.5cm×11cm, and the polyester resin layer of the sheet was laminated on a glass plate, and then the release film was peeled off. This operation was repeated 6 times to obtain a test sheet having a polyester resin layer with a thickness of 390 μm on a glass plate.
The test plate thus obtained was immersed in purified water at 23℃for 24 hours, and then the surface was taken out and wiped off with moisture, and dried at 70℃for 2 hours. The required weight was measured in each of these steps, and the water absorption (wt%) was calculated from the weight change according to the following formula.
(c-d)×100/(b-a)
A: weight of glass sheets alone
B: weight of initial test plate
C: weight of test plate immediately after removal of water from purified water
D: weight of the test plate after drying at 70℃for 2 hours
The content of the polyester resin (A2) in the polyester resin in the adhesive composition of the present invention is preferably more than 50% by weight, more preferably 70% by weight or more, particularly preferably 85% by weight or more of the entire polyester resin. If the content is too small, the hygroscopicity tends to be low and the long-term durability in a hot and humid environment tends to be insufficient.
< Polyepoxide Compound (B) >)
The adhesive composition of the present invention preferably further contains a polyepoxide compound (B). The polyepoxide compound (B) used in the present invention is the same as the content of < polyepoxide compound (B) > described in the first embodiment, and therefore, description thereof is omitted here.
< Adhesive composition >
The adhesive composition of the present invention contains at least a polyester resin (A2), preferably a polyepoxide compound (B), and exhibits the effects of low hygroscopicity, high adhesiveness, and excellent long-term durability under hot and humid environments.
In the adhesive composition of the present invention, the content of any component such as filler, flame retardant, polyepoxide compound (B), solvent, and other component contained therein is the same as that of < adhesive composition > described in the first embodiment, and therefore, description thereof is omitted here.
< Adhesive >
The adhesive of the present invention is obtained by curing the adhesive composition, and has the effects of excellent initial adhesion, low hygroscopicity, and long-term durability in a hot and humid environment.
The adhesive of the present invention is the same as the < adhesive > described in the first embodiment, and therefore, description thereof is omitted here.
Third mode
The adhesive composition of the present invention contains at least a polyester resin containing structural units derived from polycarboxylic acids and structural units derived from polyols. First, a polyester resin will be described.
< Polyester resin >
The polyester resin preferably contains a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol in the molecule, and is obtained by bonding a polycarboxylic acid and a polyhydric alcohol by an ester bond.
[ Polycarboxylic acids ]
Examples of the polycarboxylic acid include aromatic polycarboxylic acids described below; a 3-or more-membered polycarboxylic acid having 0 or 1 acid anhydride group; alicyclic polycarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid and anhydrides thereof; aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and the like. The polycarboxylic acid may be used in an amount of 1 or 2 or more.
The polycarboxylic acids contain aromatic polycarboxylic acids. Examples of the aromatic polycarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, dimethyl isophthalate, phthalic acid, naphthalene dicarboxylic acid, dimethyl naphthalene dicarboxylic acid, and biphenyl dicarboxylic acid, and derivatives thereof (aromatic dicarboxylic acids). Examples of the carboxylic acids include aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Further, tri-or more functional aromatic carboxylic acids introduced for the purpose of imparting a branched skeleton and an acid value to the polyester resin are also included in the aromatic polycarboxylic acids. Examples of the aromatic carboxylic acid in the three-or higher-functional aromatic carboxylic acids include trimellitic acid, trimesic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3',4,4' -diphenylsulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
Among these, aromatic dicarboxylic acids are preferable, isophthalic acid, dimethyl isophthalate, and dimethyl naphthalenedicarboxylate are particularly preferable, and dimethyl naphthalenedicarboxylate is further preferable from the viewpoint of low dielectric characteristics.
The content of the aromatic polycarboxylic acid based on the entire polycarboxylic acid is preferably 25 mol% or more, more preferably 40 mol% or more, still more preferably 70 mol% or more, particularly preferably 90 mol% or more, and most preferably 100 mol%. If the content of the aromatic polycarboxylic acid is too small, the following tends to occur: the long-term durability under hot and humid environments becomes insufficient or is poor in terms of low dielectric loss tangent.
The content (molar ratio) of the aromatic polycarboxylic acid relative to the entire polycarboxylic acid is determined by the following formula.
Aromatic acid content (mol%) = (aromatic polycarboxylic acid (mol)/polycarboxylic acid (mol)) ×100
The content of the aromatic polycarboxylic acid based on the entire polyester resin is preferably 15 to 70% by weight, more preferably 20 to 65% by weight, still more preferably 25 to 60% by weight, and particularly preferably 30 to 55% by weight. If the content of the aromatic polycarboxylic acid is too small, initial adhesion tends to be insufficient, or the low dielectric loss tangent tends to be poor, and if it is too large, initial adhesion tends to be insufficient.
The polycarboxylic acids preferably further contain 3-or more polycarboxylic acids having 0 or 1 acid anhydride group. The valence of the carboxyl group in the polycarboxylic acid is preferably 3 to 6, more preferably 3 to 4. Examples of the polycarboxylic acids include those having 0 or 1 acid anhydride group in the above tri-or higher aromatic polycarboxylic acids. Examples of these include trimellitic anhydride, trimellitic acid, and among these, a substance having 1 acid anhydride group is preferable, and trimellitic anhydride is particularly preferable.
Examples of the polycarboxylic acids having 3 or more acid anhydride groups of 0 or 1 include hydrogenated trimellitic anhydride and the like, in addition to aromatic polycarboxylic acids.
From the viewpoint of hygroscopicity of the polyester resin, the content of the aromatic dicarboxylic acid having a sulfonate group such as sulfonic acid terephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2, 7-dicarboxylic acid, 5- (4-sulfophenoxy) isophthalic acid, and the like, and the content of the aromatic dicarboxylic acid having a sulfonate group such as a metal salt or an ammonium salt thereof, relative to the entire polycarboxylic acid, is preferably 10 mol% or less, more preferably 5 mol% or less, particularly preferably 3 mol% or less, further preferably 1 mol% or less, and most preferably 0 mol%.
[ Polyhydric alcohols ]
Examples of the polyhydric alcohol include a dimer alcohol, a bisphenol skeleton-containing monomer, an aliphatic polyhydric alcohol, an alicyclic polyhydric alcohol, and an aromatic polyhydric alcohol. The polyhydric alcohol may be used in an amount of 1 or 2 or more.
In the present invention, the compound constituting the polyester resin preferably contains a dimer alcohol as a polyol.
Examples of the dimer alcohols include dimer alcohols which are the reduced products of dimer acids (mainly those having 36 to 44 carbon atoms) derived from oleic acid, linoleic acid, linolenic acid, erucic acid, and the like, and hydrides thereof. Among them, from the viewpoint of suppressing gelation at the time of producing a polyester resin, a hydride is preferable.
The content of the dimer alcohol relative to the entire polyol is preferably 5 to 80 mol%, more preferably 10 to 60 mol%, particularly preferably 15 to 55 mol%, and further preferably 20 to 50 mol%. If the content of the dimer alcohol is too small, the hygroscopicity tends to be low and the dielectric characteristics tend to be poor, and if the content is too large, the initial adhesiveness tends to be insufficient.
The content of the dimer alcohol relative to the entire polyester resin is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, still more preferably 15 to 55% by weight, and particularly preferably 20 to 50% by weight. If the content of the dimer alcohol is too small, the hygroscopicity tends to be low and the dielectric characteristics tend to be poor, and if the content is too large, the initial adhesiveness tends to be insufficient.
Examples of the monomer having a bisphenol skeleton include bisphenol a, bisphenol B, bisphenol E, bisphenol F, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, 4' -dihydroxybenzophenone, bisphenol fluorene, and a hydride thereof; ethylene oxide adducts and the like obtained by adding 1 to several moles of ethylene oxide or propylene oxide to the hydroxyl groups of bisphenols, glycols and the like such as propylene oxide adducts and the like. Among them, bisphenol fluorene having a condensed polycyclic aromatic skeleton is preferable from the viewpoint of low dielectric characteristics, ethylene oxide adduct is preferable from the viewpoint of reactivity, ethylene oxide 2 to 3mol adduct is preferable from the viewpoint of heat resistance, low hygroscopicity and long-term durability under a humid and hot environment, and diphenoxyethanol fluorene is most preferable.
From the viewpoint of low dielectric characteristics, it is preferable that the amount of monomers containing a bisphenol skeleton other than bisphenol fluorene and its derivative is small, and from the viewpoints of solvent solubility of the polyester resin, storage stability of the solution, and low hygroscopicity, it is preferable that the amount of monomers containing a bisphenol skeleton other than bisphenol fluorene and its derivative is large, and it is preferable that the amount of monomers to be introduced is adjusted in accordance with desired physical properties. On the other hand, in view of any physical properties of the solvent solubility, the storage stability of the solution, the low hygroscopicity and the low dielectric properties, it is also preferable to introduce bisphenol fluorene and its derivative into the polyester resin, and the content of bisphenol fluorene and its derivative relative to the entire polyol is preferably 5 to 50 mol%, more preferably 10 to 45 mol%, particularly preferably 15 to 40 mol%, and even more preferably 20 to 35 mol%. If the content of bisphenol fluorene or a derivative thereof is too large, initial adhesiveness tends to be insufficient, and if it is too small, solvent solubility, storage stability, low hygroscopicity, and dielectric characteristics tend to be insufficient.
Examples of the aliphatic polyhydric alcohol include ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 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, dimethylolheptane, and 2, 4-trimethyl-1, 3-pentanediol. Among them, a polyol having 5 or less carbon atoms is preferably used from the viewpoint of improving the aromatic ring content described later.
Examples of the alicyclic polyol include 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.
Examples of the aromatic polyol include paradimethanol, isophthaloyl dimethanol, phthalic dimethanol, 1, 4-benzenediol, and ethylene oxide adducts of 1, 4-benzenediol.
Among the above polyols, a polyol having a side chain is preferably used from the viewpoints of solvent solubility and solution stability. Examples of the polyhydric alcohol having a side chain include bisphenol a, bisphenol B, bisphenol E, bisphenol AP, bisphenol BP, bisphenol P, bisphenol PH, bisphenol S, bisphenol Z, bisphenol fluorene, and hydrogenated products thereof; and a monomer having a bisphenol skeleton, such as an ethylene oxide adduct obtained by adding 1 to several moles of ethylene oxide or propylene oxide to a bisphenol hydroxyl group, and a propylene oxide adduct; aliphatic polyhydric alcohols having a side chain such as 1, 2-propanediol, 2-methyl-1, 3-propanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 2-ethyl-2-butylpropanediol, dimethylolheptane, and 2, 4-trimethyl-1, 3-pentanediol; alicyclic polyols having side chains such as tricyclodecanediol, tricyclodecanedimethanol and spirodiol.
The content of the polyhydric alcohol having a side chain is preferably 10 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more, based on the entire polyhydric alcohol. The upper limit is 95 mol%. Further, the content is 5% by weight or more, more preferably 10% by weight or more, and still more preferably 15% by weight or more, based on the entire polyester resin. The upper limit is 50% by weight.
If the content of the polyhydric alcohol having a side chain is too small, the solvent solubility and the solution stability of the obtained polyester resin solution tend to be lowered.
The content of the ether bond-containing diol other than the bisphenol skeleton-containing monomer such as diethylene glycol, triethylene glycol, dipropylene glycol, and polyethylene glycol, polypropylene glycol, polytetramethylene glycol is preferably 20% by weight or less, more preferably 15% by weight or less, particularly preferably 10% by weight or less, further preferably 8% by weight or less, and most preferably 5% by weight or less, based on the entire polyester resin, from the viewpoints of heat resistance, low hygroscopicity, and long-term durability under hot and humid environments.
[ Whole of raw material Compound constituting polyester resin ]
The compound constituting the polyester resin is preferably from the viewpoint of low dielectric loss tangent: at least one of the polycarboxylic acids and the polyols contains a condensed polycyclic aromatic compound. Examples of the condensed polycyclic aromatic compound include naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dimethyl ester, anthracene dicarboxylic acid, and the like, and naphthalene dicarboxylic acid is preferable from the viewpoint of price and ease of acquisition, and naphthalene dicarboxylic acid dimethyl ester is more preferable from the viewpoint of reactivity. They may be used singly or in combination of 2 or more. Examples of the condensed polycyclic aromatic compound of the polyhydric alcohol include bisphenol fluorene and its derivatives such as ethylene oxide and propylene oxide adducts, and among them, ethylene oxide adducts are preferable, and diphenoxyethanol fluorene is particularly preferable. They may be used singly or in combination of 2 or more.
In the present invention, from the viewpoint of low dielectric loss tangent, it is preferable to increase the aromatic ring content.
From the viewpoint of low dielectric loss tangent, the aromatic ring content is preferably 10% by weight or more, more preferably 15% by weight or more, particularly preferably 20% by weight or more, and further preferably 25% by weight or more, relative to the entire polyester resin. The upper limit is usually 50% by weight.
Here, the definition and calculation method of the aromatic ring content in the present invention are as follows.
The aromatic ring content refers to: the weight ratio of atoms constituting the aromatic ring in the polyester resin. The two aromatic ring portions derived from the bisphenol skeleton are not included in the aromatic ring content of the present invention because they do not contribute to low dielectric characteristics. The reason why the two aromatic ring moieties derived from the bisphenol skeleton do not contribute to the low dielectric loss tangent is not yet determined, presumably because: for example, from a steric factor, two aromatic rings derived from a bisphenol skeleton cannot participate in stacking of aromatic rings with each other.
The aromatic ring content was calculated from the composition of the polyester resin. The calculation method is as follows.
Aromatic ring content =A1×(a11×m11+a12×m12+a13×m13…)/(x1-y1)+A2×(a21×m21+a22×m22+a23×m23…)/(x2-y2)+A3×(a31×m31+a32×m32+a33×m33…)/(x3-y3)…
A: content (wt%) of structural unit derived from each monomer in the polyester resin
A: the atomic weight of the atoms constituting the aromatic ring in each monomer (for example, 12 if carbon, 14 if nitrogen, etc. in addition, when there are 2 or more atoms, a11, a12, a13, … corresponding to the above formula, for example, a11:carbon, a12:nitrogen, a13:oxygen.)
M: number of atoms constituting aromatic ring in each monomer
X: molecular weight of the monomers
Y: sum of the formula weights of the groups released in the monomers
The two aromatic ring sites derived from the bisphenol skeleton are not included in the atoms constituting the aromatic ring (considered as m=0) for the above reasons.
In addition, a hydroxycarboxylic acid compound having a hydroxyl group and a carboxyl group in the molecular structure can also be used as a raw material compound for the polyester resin. Examples of the hydroxycarboxylic acid compound include 5-hydroxyisophthalic acid, parahydroxybenzoic acid, parahydroxyphenylpropionic acid, parahydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4, 4-bis (parahydroxyphenyl) valeric acid.
In the polyester resin used in the present invention, at least one selected from the group consisting of tri-or higher-functional polycarboxylic acids and tri-or higher-functional polyols is preferably copolymerized for the purpose of introducing a branched skeleton, in addition to the polycarboxylic acids used in the depolymerization reaction described later. In particular, when a cured coating film is obtained by reacting the resin with a curing agent, a coating film having an increased terminal group concentration (reaction site) of the resin, a high crosslinking density and high toughness can be obtained by introducing a branched skeleton.
Examples of the polycarboxylic acids having three or more functions include trimellitic acid, ethylene glycol bis (dehydrated trimellitate), glycerol tris (dehydrated trimellitate), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3', and 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
Examples of the trifunctional or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and the like.
The trifunctional or higher polycarboxylic acid and the trifunctional or higher polyol may be used in an amount of 1 or 2 or more, respectively.
When at least one selected from the group consisting of tri-or higher polycarboxylic acids and tri-or higher polyols is used for the purpose of introducing a branched skeleton, the content of tri-or higher polycarboxylic acids relative to the whole polycarboxylic acids or the content of tri-or higher polyols relative to the whole polyols is preferably in the range of 0.1 to 5 mol%, more preferably 0.3 to 3 mol%, still more preferably 0.5 to 2 mol%, respectively, unlike the polycarboxylic acids used in the depolymerization reaction described later. If the content of either or both of the components is too large, mechanical properties such as elongation at break point of a coating film formed by applying the adhesive tend to be lowered, and the adhesive strength tends to be lowered, and gelation tends to occur during polymerization.
[ Production of polyester resin ]
The polyester resin used in the present invention can be produced by a known method. For example, the polyester resin can be produced by esterifying a polycarboxylic acid with a polyhydric alcohol in the presence of a catalyst if necessary to obtain a polyester resin, and introducing an acid value.
Examples of the method for introducing an acid value into a polyester resin include a method for introducing a carboxylic acid into a resin by acid addition after an esterification reaction and a reduced pressure polycondensation. If monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compounds are used for the acid addition, the molecular weight may be reduced by transesterification, and preferably, a compound having at least one carboxylic anhydride is used. Examples of the acid anhydride include succinic anhydride, maleic anhydride, phthalic anhydride, 2, 5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -diphenyltetracarboxylic dianhydride, 3', and 4,4' -diphenyl sulfone tetracarboxylic dianhydride, 4'- (hexafluoroisopropylidene) diphthalic dianhydride, 2' -bis [ (dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.
If the total amount of the polycarboxylic acids constituting the polyester resin is 100 mol%, gelation may occur if 15 mol% or more of the acid addition is performed. Examples of the method of acid addition include a method of direct addition in a bulk state and a method of adding a polyester in a solution. Although the reaction rate is high in the bulk state, gelation may occur in the case of addition in a large amount, and the reaction may be performed at a high temperature, and therefore, attention must be paid to blocking oxygen to prevent oxidation or the like. On the other hand, although the addition reaction in the solution state is slow, a large amount of carboxyl groups can be stably introduced.
In addition, when a polyester resin having a carboxyl group in a side chain is obtained, a method of reacting a polycarboxylic acid anhydride with a hydroxyl group-containing prepolymer obtained by copolymerizing a polycarboxylic acid other than the polycarboxylic acid anhydride with a polyhydric alcohol is preferable from the viewpoint of productivity.
In the present invention, the polymer may be produced by other known methods, for example, esterification of a polycarboxylic acid and a polyhydric alcohol in the presence of a catalyst if necessary to obtain a prepolymer, polycondensation, and depolymerization.
The temperature in the esterification reaction of the polycarboxylic acids with the polyols is generally 180 to 280℃and the reaction time is generally 60 minutes to 8 hours.
The temperature in polycondensation is generally 220 to 280℃and the reaction time is generally 20 minutes to 4 hours. In addition, the polycondensation is preferably carried out under reduced pressure.
From the viewpoint of initial adhesiveness, it is preferable to use a polycarboxylic acid having 3 or more members and having 0 or 1 acid anhydride group. Examples of the polycarboxylic acids having 3 or more acid anhydride groups of 0 or 1 include compounds such as trimellitic acid, trimellitic anhydride, hydrogenated trimellitic anhydride, and trimesic acid. From the viewpoint of suppressing a decrease in molecular weight, polycarboxylic acids having 3 or more members and 1 acid anhydride group are preferable, and examples thereof include trimellitic anhydride and hydrogenated trimellitic anhydride, and from the viewpoint of low dielectric loss tangent, trimellitic anhydride is preferable.
The temperature in depolymerization is usually 200 to 260℃and the reaction time is usually 10 minutes to 3 hours.
When the total of the polycarboxylic acids constituting the polyester resin is 100 mol%, if the depolymerization is performed using more than 20 mol% of the polycarboxylic acids having 3 or more acid anhydride groups of 0 or 1, the molecular weight of the resin may be significantly reduced. Therefore, when the total polycarboxylic acids constituting the polyester resin are 100 mol%, it is preferable to depolymerize the polyester resin with 20 mol% or less of polycarboxylic acids having 3 or more acid anhydride groups of 0 or 1, more preferably 1 to 15 mol%, particularly preferably 2 to 10 mol%, and still more preferably 3 to 8 mol%.
[ Glass transition temperature (Tg) ] of polyester resin
The glass transition temperature (Tg) of the polyester resin used in the present invention is the same as that described in the first embodiment. That is, the temperature is not less than-5 ℃, preferably 0 to 100 ℃, more preferably 3 to 80 ℃, particularly preferably 5 to 60 ℃, further preferably 7 to 40 ℃, and most preferably 10 to 30 ℃.
If the glass transition temperature (Tg) is too low, initial adhesion and non-tackiness become insufficient. If the glass transition temperature (Tg) is too high, initial adhesiveness and bendability tend to be insufficient.
The method for measuring the glass transition temperature (Tg) is as follows.
The glass transition temperature (Tg) can be determined by measurement using a differential scanning calorimeter. The measurement conditions were such that the measurement temperature was in the range of-70 to 140℃and the temperature rise rate was 10℃per minute.
[ Acid value of polyester resin ]
The acid value of the polyester resin used in the present invention is 3mgKOH/g or more, preferably 4 to 60mgKOH/g, more preferably 5 to 40mgKOH/g, particularly preferably 6 to 30mgKOH/g, and further preferably 7 to 20mgKOH/g.
When the acid value is too low, the curing agent such as a polyepoxide compound is contained in the adhesive composition, and the crosslinking site with the curing agent is insufficient, and the degree of crosslinking becomes low, so that the heat resistance becomes insufficient. In addition, if the acid value is too high, hygroscopicity, long-term durability under a hot and humid environment are lowered, or a large amount of a curing agent is required at the time of curing, so that it is liable that it is difficult to obtain low dielectric characteristics which have been demanded to be increased in recent years.
The definition and measurement method of the acid value are as follows.
The acid value (mgKOH/g) can be obtained by dissolving 1g of the polyester resin in 30g of a mixed solvent of toluene/methanol (for example, toluene/methanol=7/3 by volume ratio) and performing neutralization titration in accordance with JIS K0070.
In the present invention, the acid value of the polyester resin is due to the carboxyl group content in the resin.
[ Concentration of ester bond in polyester resin ]
The concentration of the ester bond in the polyester resin used in the present invention is preferably 7.5 mmol/g or less, more preferably 2 to 7 mmol/g, still more preferably 2.5 to 6.5 mmol/g, particularly preferably 3 to 6 mmol/g, and particularly preferably 3.1 to 5.5 mmol/g.
If the ester bond concentration is too high, the low hygroscopicity tends to be insufficient, and if the ester bond concentration is too low, the initial adhesiveness tends to be insufficient.
The definition and measurement method of the ester bond concentration are the same as those described in the first embodiment. Namely, as follows.
The ester bond concentration (mmol/g) is the number of moles of ester bonds in 1g of the polyester resin, and is calculated, for example, from the calculated value derived from the amount of the polyester resin fed. The calculation method is a value obtained by dividing the number of moles of the smaller one of the amounts of polycarboxylic acids and polyols by the total weight of the resin, and an example of the calculation formula is shown below.
The amounts of the polycarboxylic acids and the polyhydric alcohols to be added are the same in terms of the molar amounts. Any of the following formulas may be used.
In addition, when a substance having both a carboxyl group and a hydroxyl group, or when a polyester is produced from caprolactone or the like is used as a monomer, the calculation method is appropriately changed.
(The polycarboxylic acid is less than the polyhydric alcohol)
Concentration of ester group (mmol/g) = [ (A1/a1×m1+A2/a2×m2+A3/a3×m3 …)/Z ] ×1000
A: charge amount (g) of polycarboxylic acid
A: molecular weight of polycarboxylic acids
M: number of carboxylic acid groups per 1 molecule of polycarboxylic acid
Z: weight of finished product (g)
(Where polyols are less than polycarboxylic acids)
Concentration of ester group (mmol/g) = [ (B1/b1×n1+B2/b2×n2+B3/b3×n3 …)/Z ] ×1000
B: amount of polyol (g)
B: molecular weight of polyol
N: number of hydroxyl groups per 1 molecule of polyol
Z: weight of finished product (g)
The ester bond concentration may be measured by a known method using NMR or the like.
The concentration of the other polar groups other than the ester bond and the reactive functional group is the same as that described in the first embodiment. That is, from the viewpoints of low hygroscopicity and long-term durability in a hot and humid environment, a low concentration is preferable.
Examples of the other polar group include an amide group, an imide group, a urethane group, an urea group, an ether group, and a carbonate group.
The total concentration of the amide groups, imide groups, urethane groups and urea groups is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
Examples of the ether group include an alkyl ether group and a phenyl ether group, and particularly, it is preferable to reduce the concentration of the alkyl ether group from the viewpoints of low hygroscopicity and long-term durability under a hot and humid environment. The concentration of the alkyl ether group is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1.5 mmol/g or less, further preferably 1 mmol/g or less, and most preferably 0.5 mmol/g or less. The concentration of the phenyl ether group is preferably 5 mmol/g or less, more preferably 4 mmol/g or less, particularly preferably 3 mmol/g or less, and further preferably 2.5 mmol/g or less.
The carbonate group concentration is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, particularly preferably 1 mmol/g or less, further preferably 0.5 mmol/g or less, and most preferably 0.2 mmol/g or less.
[ Peak top molecular weight (Mp) and weight average molecular weight (Mw) ] of polyester-based resin
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) of the polyester resin used in the present invention are the same as those described in the first embodiment. That is, the peak top molecular weight (Mp) of the polyester resin is preferably 5000 to 150000, more preferably 10000 to 100000, particularly preferably 15000 to 70000, and further preferably 25000 to 40000.
If the peak top molecular weight (Mp) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the peak top molecular weight (Mp) is too high, the following tends to occur: the initial adhesiveness becomes insufficient; or the solution viscosity at the time of coating is too high, and it is difficult to obtain a uniform coating film.
The weight average molecular weight (Mw) of the polyester resin used in the present invention is preferably 5000 to 300000, more preferably 10000 to 200000, particularly preferably 20000 to 150000, further preferably 30000 to 100000.
If the weight average molecular weight (Mw) is too low, the following problems tend to occur: low hygroscopicity, non-sticking chirality, and long-term durability under hot and humid environments become insufficient; or the polyester resin of the adhesive layer flows and bleeds out during the press working in the production of flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. If the weight average molecular weight (Mw) is too high, the following tends to occur: the initial adhesiveness becomes insufficient; or the solution viscosity at the time of coating is too high, and it is difficult to obtain a uniform coating film.
The measurement methods of the peak top molecular weight (Mp) and the weight average molecular weight (Mw) are as follows.
The peak top molecular weight (Mp) and the weight average molecular weight (Mw) can be determined as follows: the molecular weight was measured by a high performance liquid chromatograph (manufactured by Tosoh corporation, "HLC-8320 GPC") using two columns (TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2X 10 6, theoretical plate number: 16000 grade/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 4 μm)) in series, and the molecular weight was converted to standard polystyrene.
[ Water absorption (wt.%) ] of polyester resin
The water absorption of the polyester resin used in the present invention is the same as that described in the first embodiment. That is, it is preferably 2% by weight or less, more preferably 1% by weight or less, particularly preferably 0.8% by weight or less, and further preferably 0.6% by weight or less.
If the water absorption is too high, the wet heat durability, insulation reliability and dielectric characteristics tend to be poor.
The method for measuring the water absorption is as follows.
The polyester resin solution (before compounding the curing agent) was applied to a release film by an applicator and dried at 120℃for 10 minutes to prepare a sheet having a polyester resin layer with a dried film thickness of 65. Mu.m. The sheet was cut into a size of 7.5cm×11cm, and the polyester resin layer of the sheet was laminated on a glass plate, and then the release film was peeled off. This operation was repeated 6 times to obtain a test sheet having a polyester resin layer with a thickness of 390 μm on a glass plate.
The test plate thus obtained was immersed in purified water at 23℃for 24 hours, and then the surface was taken out and wiped off with moisture, and dried at 70℃for 2 hours. The required weight was measured in each of these steps, and the water absorption (wt%) was calculated from the weight change according to the following formula.
(c-d)×100/(b-a)
A: weight of glass sheets alone
B: weight of initial test plate
C: weight of test plate immediately after removal of water from purified water
D: weight of the test plate after drying at 70℃for 2 hours
[ Dielectric Properties of polyester resin ]
(Relative permittivity (Dk))
The polyester resin used in the present invention preferably has a relative dielectric constant of 2.8 or less, more preferably 2.7 or less, particularly preferably 2.6 or less, and even more preferably 2.5 or less at a frequency of 10GHz in an atmosphere of a relative humidity of 50% rh at a temperature of 23 ℃. If the relative dielectric constant is too high, there is a tendency that the transfer speed difference and the transfer loss become large when the substrate is manufactured.
(Dielectric loss tangent (Df))
The polyester resin used in the present invention has a dielectric loss tangent of 0.005 or less, preferably 0.0045 or less, more preferably 0.004 or less, particularly preferably 0.0035 or less, further preferably 0.003 or less, particularly preferably 0.0025 or less, and most preferably 0.002 or less at a frequency of 10GHz in an atmosphere of a relative humidity of 50% rh at a temperature of 23 ℃. If the dielectric loss tangent is too high, the transmission loss when the substrate is formed becomes large.
The method for measuring the relative permittivity and dielectric loss tangent can be obtained by a cavity resonator perturbation method using a network analyzer. When the adhesion of the polyester resin is high and it is difficult to prepare a measurement sample alone, the dielectric characteristics of the polyester resin alone can be calculated by measuring the sample in a state of being sandwiched between films and subtracting the amount of the films.
Thus, the present invention can obtain a polyester resin having a very small dielectric loss tangent as compared with the conventional polyester resin.
Further, from the viewpoint of suppressing transmission loss in a high frequency range, a polyester resin having a very small dielectric loss tangent is very useful as a raw material of an adhesive used for bonding electronic material members and the like.
In the present invention, from the viewpoints of solvent solubility and solution stability, a non-crystalline polyester resin is preferable. If crystalline, the solvent solubility and the solution stability tend to be insufficient.
The non-crystallinity can be confirmed by a differential scanning calorimeter, for example, referring to: when the measurement is carried out at a temperature ranging from-70 to 400 ℃ and a temperature rise rate of 10 ℃/min, no endothermic peak due to crystal melting is observed. The measurement temperature range and the temperature rise rate may be appropriately changed according to the sample.
In the present invention, from the viewpoint of preparing an adhesive composition to be described later, it is preferable that the polyester resin is soluble in a non-halogen organic solvent. If the solubility in the organic solvent is insufficient, it tends to be difficult to prepare the adhesive composition.
The non-halogen organic solvent is, for example, an aromatic solvent such as toluene, xylene, solvent naphtha, solvosiso, etc.; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, and isobutanol; ester solvents such as ethyl acetate and n-butyl acetate; acetate solvents such as cellosolve acetate and methoxyacetate; or a mixture of two or more of these solvents.
< Curing agent >
The adhesive composition of the present invention preferably further contains a curing agent. By containing the curing agent, the functional group in the polyester resin reacts with the curing agent having a functional group reactive with the functional group, and the resulting cured product can provide an adhesive having excellent adhesion, heat resistance, and durability.
Examples of the curing agent include a compound having a functional group reactive with at least one of a hydroxyl group and a carboxyl group contained in the polyester resin, such as a polyisocyanate compound and a polyepoxide compound, and among these, polyepoxide compounds are preferable from the viewpoint of solder heat resistance.
Examples of the polyisocyanate compound include polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate, and isocyanate adducts such as toluene diisocyanate adduct, hexamethylene diisocyanate adduct, and isophorone diisocyanate adduct of trimethylolpropane. The polyisocyanate compound may be one in which an isocyanate moiety is blocked with phenol, lactam or the like. These isocyanate compounds may be used alone or in combination of 1 or more than 2.
Examples of the polyepoxide compound include difunctional glycidyl ethers such as bisphenol a diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol a diglycidyl ether; a multifunctional glycidyl ether type such as phenol novolac glycidyl ether and cresol novolac glycidyl ether; glycidyl ester types such as glycidyl hexahydrophthalate and glycidyl dimer acid; triglycidyl isocyanurate, 3, 4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, epoxidized soybean oil and other alicyclic or aliphatic epoxides, and the like. The polyepoxide compound may be used in an amount of 1 or 2 or more. Among them, the glycidyl ether type and the glycidyl ester type are preferable from the viewpoint of reactivity, the glycidyl ether type is preferable from the viewpoint of wet heat durability, and the polyfunctional type is preferable from the viewpoint of solder heat resistance.
The epoxy equivalent of the polyepoxide compound is preferably 500g/eq or less, more preferably 350g/eq or less, particularly preferably 250g/eq or less, and further preferably 200g/eq or less. If the epoxy equivalent of the polyepoxide compound is too large, the crosslink density after curing becomes low, and therefore, solder heat resistance is poor or a large amount of polyepoxide compound must be added to achieve the crosslink density, and therefore, dielectric characteristics tend to be poor.
Further, when a polyepoxide compound containing a nitrogen atom (a polyepoxide compound containing a nitrogen atom) is included as the polyepoxide compound, the following tends to be included: the coating film of the adhesive composition can be B-stageable (semi-solid state) by heating at a relatively low temperature, and the fluidity of the B-stageable film can be suppressed to improve workability in the bonding operation. In addition, the effect of suppressing the foaming of the B-stage film can be expected, and is preferable.
Examples of the nitrogen atom-containing polyepoxide compound include glycidyl amines such as tetraglycidyl diaminodiphenylmethane, triglycidyl para-aminophenol, tetraglycidyl bisaminomethyl cyclohexanone, and N, N' -tetraglycidyl meta-xylylenediamine.
The adhesive composition of the present invention contains a polyepoxide compound, and when the polyepoxide compound contains these polyepoxide compounds containing nitrogen atoms, the content of the polyepoxide compound containing nitrogen atoms is preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less, relative to the entire polyepoxide compound.
The content of the nitrogen atom-containing polyepoxide compound is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and particularly preferably 2 parts by weight or less, based on 100 parts by weight of the polyester resin.
If the content of the nitrogen atom-containing polyepoxide compound is too large, the rigidity tends to be excessively high and the adhesiveness tends to be lowered, and the crosslinking reaction tends to occur during the storage of the adhesive sheet and the sheet life tends to be lowered.
The equivalent weight of the epoxy group to the carboxyl group is preferably 0.8 to 5, more preferably 0.9 to 3, particularly preferably 1 to 2.5, and further preferably 1.2 to 2.
If the equivalent amount is too large, initial adhesion and low hygroscopicity tend to be insufficient or dielectric characteristics tend to be poor. If too small, the long-term durability and solder heat resistance in a hot and humid environment tend to be insufficient.
The equivalent weight of the epoxy group to the carboxyl group (COOH) is determined from the acid value of the polyester resin and the epoxy equivalent weight (g/eq) of the polyepoxide compound to be compounded.
Equivalent of epoxy group to cooh= (a/WPE)/(AV/56.1/1000×b)
A: weight (g) of polyepoxide compound used in the compounding
WPE: epoxy equivalent (g/eq) of polyepoxide
AV: acid value of polyester resin (mgKOH/g)
B: weight (g) of polyester resin used in compounding
< Adhesive composition >
The adhesive composition of the present invention contains at least the polyester resin of the present invention, and preferably contains a curing agent, and exhibits the effects of excellent low dielectric characteristics, low hygroscopicity, high adhesion, and excellent long-term durability under hot and humid environments.
In the adhesive composition of the present invention, a filler, a flame retardant, and the like may be blended, and in this case, the content of the polyester resin of the present invention in the adhesive composition is preferably 30% by weight or more, more preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight, and further preferably 60 to 85% by weight, based on the entire solid content, in consideration of the filler, the flame retardant, and the like.
When the adhesive composition of the present invention contains a curing agent, the content of the curing agent is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, particularly preferably 3 to 15 parts by weight, and further preferably 4 to 10 parts by weight, based on 100 parts by weight of the polyester resin of the present invention. If the content of the curing agent is too small, heat resistance and long-term durability under a hot and humid environment tend to be insufficient, and if too large, initial adhesion and low hygroscopicity tend to be insufficient or dielectric characteristics tend to be poor.
In order to appropriately adjust the viscosity of the adhesive composition, the adhesive composition of the present invention may be mixed with a solvent for easy handling in forming a coating film. The solvent is used for ensuring handling and workability in molding the adhesive composition, and the amount thereof is not particularly limited.
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; aromatic compounds such as toluene and xylene. The above-listed solvents may be used in an amount of 1, or may be used in an amount of 2 or more in any combination and ratio.
[ Other ingredients ]
The adhesive composition of the present invention may contain other components than those listed above for the purpose of further improving the functionality thereof. Examples of the other components include inorganic fillers, coupling agents such as silane coupling agents, ultraviolet screening agents, antioxidants, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, low-elasticity agents, diluents, antifoaming agents, ion capturing agents, leveling agents, catalysts, and the like.
When the adhesive composition of the present invention contains other components, the content of the other components is preferably 70% by weight or less, more preferably 0.05 to 60% by weight, particularly preferably 0.1 to 50% by weight, and further preferably 0.2 to 40% by weight.
< Adhesive >
The adhesive of the present invention is obtained by curing the adhesive composition, and exhibits the effects of initial adhesion, low hygroscopicity, and excellent long-term durability in a hot and humid environment.
The adhesive of the present invention is the same as the < adhesive > described in the first embodiment, and therefore, description thereof is omitted here.
[ Use ]
The adhesive of the present invention is effective for bonding a substrate made of various materials such as resin and metal, and is particularly suitable for an adhesive used for producing a laminate of a metal layer and a plastic layer, for example, an adhesive used for bonding an electronic material member, because it is excellent in initial adhesion, low hygroscopicity, and long-term durability under a hot and humid environment.
Examples of the "electronic material member" in the present invention include a flexible printed board, a cover layer, and a bonding sheet.
Examples of the product produced by bonding the electronic material members include flexible laminated boards such as flexible copper-clad laminated boards and flexible printed boards. The flexible laminate is a laminate obtained by stacking, for example, "flexible substrate having flexibility/adhesive layer/conductive metal layer made of copper, aluminum, an alloy thereof, or the like" in this order, and the adhesive of the present invention can be used as an adhesive constituting the adhesive layer. 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
The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples within a range not exceeding the gist thereof. In the examples, "parts" and "%" refer to weight basis.
First mode
The ratio (mol%) of the aromatic polycarboxylic acid to the entire polycarboxylic acid (referred to as "aromatic acid content" in Table 1-1), the ester bond concentration (mmol/g), the water absorption, the glass transition temperature (. Degree.C.), the acid value (mgKOH/g), the peak top molecular weight (Mp), the weight average molecular weight (Mw), and the equivalent weight of the epoxy group to COOH were measured according to the description of the present specification.
< Production of polyester resin >
The composition (molar ratio) shown in the following Table 1-1 is the composition ratio (resin composition ratio) of the final product, and is the relative ratio (molar ratio) of the amounts of the respective constituent monomers of the obtained polyester resin.
[ Production example 1-1: production of polyester resin (A1-1)
To a reaction vessel equipped with a thermometer, a stirrer, a rectifying column and a nitrogen inlet tube, 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as a polycarboxylic acid, about 2 mol of ethylene oxide adduct "NEWPOL BPE-20" (BPE-20) (Sanyo chemical industry Co., ltd.) of bisphenol A as a polyhydric alcohol, 223.9 parts (0.6868 mol) of neopentyl glycol (NPG) 28.6 parts (0.2746 mol), 254.4 parts (0.4801 mol) of dimer alcohol "PRIPOL 2033" (P2033) (CRODA Co., ltd.) and 0.1 part of tetrabutyltitanate as a catalyst were charged, and an esterification reaction was carried out at 270℃for 3 hours after 120 minutes until the internal temperature reached 270 ℃.
Then, the internal temperature was lowered to 200℃and 15.0 parts (0.0688 mol) of pyromellitic dianhydride (PMAn) was added thereto, followed by an addition reaction at 200℃for 2 hours, to obtain a polyester resin (A1-1) having the resin composition and physical properties shown in Table 1-1.
[ Production examples 1-2, comparative production examples 1-1 to 1-3: production of polyester resins (A1-2, A1' -1, A1' -2, A1' -3)
The same procedure as for A1-1 was repeated except that the resin composition was changed as shown in Table 1-1 to obtain polyester resins (A1-2, A1' -1, A1' -2, A1' -3).
The resin composition (structural unit derived from the component) and the physical properties of the obtained polyester resin are shown in Table 1-1. In Table 1-1, the abbreviations are as follows.
"TPA": terephthalic acid
"IPA": isophthalic acid
"AdA": adipic acid
"P1010": dimer acid "PRIPOL 1010" (manufactured by CRODA Co.)
"PMAn": pyromellitic dianhydride
"BPDA":3,3', 4', -diphenyltetracarboxylic dianhydride
"EG": ethylene glycol
"NPG": neopentyl glycol
"BPE-20": about 2 mol adduct "NEWPOL BPE-20" of bisphenol A ethylene oxide (Sanyo chemical industry Co., ltd.)
"P2033": dimer alcohol "PRIPOL 2033" (manufactured by CRODA Co., ltd.)
[ Table 1-1]
< Polyepoxide Compound (B) >)
The following compounds were prepared as the polyepoxide compound (B).
(B1-1): phenol novolac type epoxy resin "YDPN-638" (manufactured by Nitro iron chemical & materials Co., ltd.) (WPE=177 (g/eq))
< Production of adhesive composition >
Using the polyester resin and the polyepoxide compound obtained as described above, an adhesive composition was produced as follows.
Example 1-1
The polyester resin (A1-1) obtained above was diluted with methyl ethyl ketone to a solid content of 60%, and 10 parts of the polyepoxide compound (B1-1) (solid content) was mixed with the polyester resin (A1-1) solution (100 parts by solid content), and further diluted, stirred and mixed with methyl ethyl ketone to a solid content of 50%, thereby obtaining an adhesive composition.
Examples 1-2 to 1-3 and comparative examples 1-1 to 1-5
In example 1-1, adhesive compositions were obtained in the same manner as described in Table 1-2 except that the resin compositions were prepared.
The adhesive composition obtained was used for evaluation as follows. The results are shown in tables 1 to 2.
< Preparation of laminate >
The adhesive composition prepared above was applied to a polyimide film "KAPTON 200H" (manufactured by eastern dupont) having a thickness of 50 μm by an applicator, and then dried at 120 ℃ for 5 minutes to form an adhesive layer having a dry film thickness of 25 μm. Next, (1) a rolled copper foil having a thickness of 30 μm or (2) a polyimide film "KAPTON 200H" having a thickness of 50 μm was laminated on the adhesive layer surface of the polyimide film with an adhesive layer (lamination condition: 170 ℃ C., 0.2MPa, feed speed: 1.5 m/min), followed by heat treatment in an oven at 160 ℃ C. For 4 hours to cure the laminate, thereby obtaining each laminate.
For convenience, the laminate laminated with the rolled copper foil (polyimide film/adhesive layer/rolled copper foil) was designated PI/Cu, and the laminate laminated with the polyimide film (polyimide film/adhesive layer/polyimide film) was designated PI/PI.
< Evaluation >
[ Initial adhesion ]
The laminate obtained above was cut into 1cm wide pieces and used as test pieces. The test piece was fixed to a glass plate having a thickness of 2mm using a double-sided tape, and the tensile peel strength (peel speed: 50mm/min, peel angle: 180 °) of the test piece was measured using a peel tester at 23℃under 50% RH. The evaluation criteria are as follows.
And (3) the following materials: 8N/cm or more
O: 6N/cm or more and less than 8N/cm
Delta: 4N/cm or more and less than 6N/cm
X: less than 4N/cm
[ Durability to damp-heat ]
The PI/Cu test piece was placed in a constant temperature and humidity machine at 85 ℃ and 85% rh, taken out after a predetermined time, allowed to stand in an environment at 23 ℃ and 50% rh for one night, and then subjected to the same operation as the initial adhesion to measure the tensile peel strength. The percentage of the adhesive force after the wet heat treatment to the initial adhesive force was set as "maintenance rate".
The absolute value of the adhesive force was evaluated using the same evaluation criterion as the initial adhesive force.
The maintenance rate of the adhesive force was evaluated based on the following evaluation criteria.
And (3) the following materials: the maintenance rate is more than 80 percent
O: the maintenance rate is more than 60% and less than 80%
Delta: the maintenance rate is more than 40% and less than 60%
X: the maintenance rate is less than 40 percent
[ Non-sticking chirality ]
The adhesive layer surface of the polyimide film with an adhesive layer before curing obtained as described above was lightly touched with a finger, and evaluated based on the following evaluation criteria.
And (3) the following materials: almost no stickiness was felt.
And (2) the following steps: less sticky feeling.
Delta: slightly sticky.
X: is stuck on the finger.
[ Gel fraction ]
The polyimide film with an adhesive layer obtained above was cured by heat treatment at 160℃for 4 hours, and then cut into a size of 4 cm. Times.4 cm. The resultant was wrapped with a 200 mesh SUS-made metal mesh, and immersed in methyl ethyl ketone at 23℃for 24 hours, whereby the percentage of the weight of the insoluble adhesive component remaining in the metal mesh relative to the weight of the adhesive before immersion was set as a gel fraction.
[ Tables 1-2]
Based on the results of tables 1-1 and 1-2, the polyester resins (A1-1) and (A1-2) of production examples 1-1 and 1-2 satisfying the conditions of the present invention were excellent in low hygroscopicity, and the adhesive compositions of examples 1-1 to 1-3 obtained by using them were excellent in tack-free property before curing, initial adhesiveness after curing, and long-term durability under a hot and humid environment.
On the other hand, the polyester resin (A1' -1) of comparative production example 1-1 having a high ester bond concentration has high hygroscopicity, and comparative examples 1-1 and 1-2 obtained using the same have poor long-term durability under a hot and humid environment. Similarly, the adhesive compositions of comparative examples 1 to 3 and 1 to 4 obtained by using the polyester-based resin (A1' -2) of comparative production examples 1 to 2 having a high ester bond concentration were also inferior in long-term durability under hot and humid environments.
The adhesive compositions of comparative examples 1 to 5 obtained using the polyester-based resins (A1' -3) of comparative production examples 1 to 3 having a low glass transition temperature were inferior in tack-free property before curing and initial adhesiveness after curing.
Second mode
The ratio (mol%) of the aromatic polycarboxylic acid to the entire polycarboxylic acid (referred to as "aromatic acid content" in Table 2-1), the ester bond concentration (mmol/g), the water absorption, the glass transition temperature (. Degree.C.), the acid value (mgKOH/g), the peak top molecular weight (Mp), the weight average molecular weight (Mw), and the equivalent weight of the epoxy group to COOH were measured according to the description of the present specification.
< Production of polyester resin >
The composition (molar ratio) shown in the following Table 2-1 is the final composition ratio (resin composition ratio), and is the relative ratio (molar ratio) of the amounts of the respective constituent monomers of the obtained polyester resin.
[ Production example 2-1: production of polyester resin (A2-1)
231.1 Parts (1.3910 mol) of isophthalic acid (IPA), 2.7 parts (0.0141 mol) of trimellitic anhydride (TMAn), 230.1 parts (0.7058 mol) of ethylene oxide of bisphenol A (BPE-20) (Sanyo chemical industry Co., ltd.), 57.0 parts (0.9183 mol) of Ethylene Glycol (EG), 261.5 parts (0.4941 mol) of dimer alcohol "PRIPOL 2033" (P2033) (CRODA Co., ltd.) and 0.1 part of tetrabutyl titanate as a catalyst were charged into a reaction vessel equipped with a thermometer, a stirrer, a rectifying column and a nitrogen inlet tube, and the temperature was raised to 270℃until the internal temperature reached 2.5 hours, and the esterification reaction was carried out at 270℃for 1.5 hours.
Next, 0.1 part of tetrabutyl titanate as a catalyst was added thereto, and the inside of the system was depressurized to 2.5hPa, and polymerization was carried out over 3 hours.
Thereafter, the internal temperature was lowered to 240℃and 17.6 parts (0.0916 mol) of trimellitic anhydride (TMAn) was added thereto, followed by depolymerization at 240℃for 1 hour to obtain a polyester resin (A2-1).
[ Production examples 2-2 to 2-4, comparative production examples 2-5: production of polyester resins (A2-2) to (A2-4) and (A2' -5)
Polyester resins (A2-2) to (A2-4) and (A2' -5) were obtained in the same manner as in A2-1 except that the resin composition was changed as described in Table 2-1.
Comparative production example 2-1: production of polyester resin (A2' -1)
To a reaction vessel equipped with a thermometer, a stirrer, a rectifying column and a nitrogen inlet tube, 228.2 parts (1.3735 mol) of isophthalic acid (IPA) as a polycarboxylic acid, about 2 mol of ethylene oxide adduct "NEWPOL BPE-20" (BPE-20) (Sanyo chemical industry Co., ltd.) of bisphenol A as a polyhydric alcohol, 223.9 parts (0.6868 mol) of neopentyl glycol (NPG) 28.6 parts (0.2746 mol), 254.4 parts (0.4801 mol) of dimer alcohol "PRIPOL 2033" (P2033) (CRODA Co., ltd.) and 0.1 part of tetrabutyltitanate as a catalyst were charged, and an esterification reaction was carried out at 270℃for 3 hours after 2 hours until the internal temperature reached 270 ℃.
Then, the internal temperature was lowered to 200℃and 15.0 parts (0.0688 mol) of pyromellitic dianhydride (PMAn) was added thereto, followed by addition polymerization at 200℃for 2 hours to obtain a polyester resin (A2' -1).
Comparative production examples 2-2 to 2-4: production of polyester resins (A2 '-2) to (A2' -4)
Polyester resins (A2 ' -2) to (A2 ' -4) were obtained in the same manner as A2' -1 except that the resin composition was changed as described in table 2-1.
The resin composition (structural unit derived from the component) and the physical properties of the obtained polyester resin are shown in Table 2-1. The abbreviations in Table 2-1 are as follows.
"TPA": terephthalic acid
"IPA": isophthalic acid
"TMAn": trimellitic anhydride
"AdA": adipic acid
"P1009": dimer acid "PRIPOL 1009" (manufactured by CRODA Co.)
"P1010": dimer acid "PRIPOL 1010" (manufactured by CRODA Co.)
"PMAn": pyromellitic dianhydride
"BPDA":3,3', 4', -diphenyltetracarboxylic dianhydride
"EG": ethylene glycol
"NPG": neopentyl glycol
"BPE-20": about 2 mol adduct "NEWPOL BPE-20" of bisphenol A ethylene oxide (Sanyo chemical industry Co., ltd.)
"P2033": dimer alcohol "PRIPOL 2033" (manufactured by CRODA Co., ltd.)
[ Table 2-1]
< Polyepoxide Compound (B) >)
The following compounds were prepared as the polyepoxide compound (B).
(B2-1): phenol novolac type epoxy resin "YDPN-638" (manufactured by Nitro iron chemical & materials Co., ltd.) (WPE=177 (g/eq))
< Production of adhesive composition >
Using the polyester resin and the polyepoxide compound (B) obtained as described above, an adhesive composition was produced as follows.
Example 2-1
The polyester resin (A2-1) obtained above was diluted with a toluene/methyl ethyl ketone=5/1 (weight ratio) mixed solvent to a solid content concentration of 55%, and 10 parts of the polyepoxide compound (B2-1) (solid content) was mixed with the polyester resin (A2-1) solution (100 parts by solid content), and further diluted with methyl ethyl ketone to a solid content of 50%, followed by stirring and mixing, whereby an adhesive composition was obtained.
Examples 2-2 to 2-4 and comparative examples 2-1 to 2-6
In example 2-1, adhesive compositions were obtained in the same manner as in Table 2-2 except that the resin compositions were prepared.
Using the obtained adhesive composition, evaluation was performed as follows. The results are shown in Table 2-2.
< Preparation of laminate >
The adhesive composition thus produced was applied to a polyimide film "KAPTON 200H" (manufactured by eastern-dupont) having a thickness of 50 μm by an applicator, and then dried at 120℃for 5 minutes to form an adhesive layer having a dry film thickness of 25. Mu.m. Then, a rolled copper foil having a thickness of 30 μm was laminated on the adhesive layer surface of the polyimide film with an adhesive layer (lamination condition: 170 ℃ C., 0.2MPa, feed speed: 1.5 m/min), and then heat-treated with an oven at 160 ℃ C. For 4 hours to cure the laminate (PI (substrate)/Cu (adherend)) was obtained.
< Evaluation >
[ Initial adhesion ]
The laminate obtained above was cut into 1cm wide pieces and used as test pieces. The test piece was fixed to a glass plate having a thickness of 2mm using a double-sided tape, and the polyimide film side of the laminate was stretched using a peel tester at 23℃and 50% RH, and the tensile peel strength (peel speed: 50mm/min, peel angle: 180 °) of the test piece was measured. The evaluation criteria are as follows.
And (3) the following materials: 12N/cm or more
O: 9N/cm or more and less than 12N/cm
Delta: 6N/cm or more and less than 9N/cm
X: less than 6N/cm
[ Durability to damp-heat ]
The test piece was placed in a constant temperature and humidity machine at 85℃and 85% RH, taken out after a predetermined time, allowed to stand in an environment at 23℃and 50% RH for one night, and then subjected to the same operation as the initial adhesion to measure the tensile peel strength. The percentage of the adhesive force after the wet heat treatment to the initial adhesive force was set as "maintenance rate".
The absolute value of the adhesive force was evaluated using the same evaluation criteria as the initial adhesive force described above.
The maintenance rate of the adhesive force was evaluated based on the following evaluation criteria.
And (3) the following materials: the maintenance rate is more than 80 percent
O: the maintenance rate is more than 60% and less than 80%
Delta: the maintenance rate is more than 40% and less than 60%
X: the maintenance rate is less than 40 percent
[ Gel fraction ]
The polyimide film with an adhesive layer obtained above was cured by heat treatment at 160℃for 4 hours, and then cut into a size of 4 cm. Times.4 cm. The resultant was wrapped with a 200mesh SUS-made metal mesh, and immersed in methyl ethyl ketone at 23℃for 24 hours, whereby the percentage of the weight of the insoluble adhesive component remaining in the metal mesh relative to the weight of the adhesive before immersion was set as a gel fraction.
[ Table 2-2]
From the results in Table 2-1, it can be seen that: the polyester resins (A2-1) to (A2-4) satisfying the conditions of the present invention obtained in production examples 2-1 to 2-4 are excellent in low hygroscopicity. Further, as can be seen from the results of the above Table 2-2: the adhesive compositions of examples 2-1 to 2-4 obtained by using these polyester resins (A2-1) to (A2-4) are excellent in long-term durability under hot and humid environments and further have high adhesion.
On the other hand, the adhesive compositions of comparative examples 2-1 and 2-2 obtained by using the polyester resins (A2 '-1) and (A2' -2) obtained in comparative production examples 2-1 and 2-2, which were obtained by imparting an acid value based on the polycarboxylic acid (x 1) having 3 or more members excluding 0 or 1 in the number of acid anhydride groups, were excellent in long-term durability under a hot and humid environment, but were lower in adhesion than the examples.
In addition, the polyester resins (A2 '-3) and (A2' -4) having a high ester bond concentration obtained by comparing production examples 2-3 and 2-4 have high hygroscopicity, and the adhesive compositions of comparative examples 2-3 to 2-5 obtained by using these resins have good initial adhesion, but have poor long-term durability under hot and humid environments.
The polyester resins (A2' -5) having a low aromatic acid content obtained in comparative production examples 2 to 5 were low in hygroscopicity, but the adhesive compositions of comparative examples 2 to 6 obtained using these resins were low in initial adhesion and also poor in long-term durability under hot and humid environments.
Third mode
The aromatic ring content, the glass transition temperature (. Degree.C.), the acid value (mgKOH/g), the ester bond concentration (mmol/g), the peak top molecular weight (Mp), the weight average molecular weight (Mw), the dielectric characteristics, and the equivalent weight of the epoxy group to COOH were measured according to the description of the present specification. The measurement methods of other physical properties are as follows.
[ Dimer alcohol content ]
Represents the content (wt%) of the dimer alcohol relative to the polyester resin.
< Production of polyester resin >
The composition shown in Table 3-1 below is the composition ratio (resin composition ratio) of the final product, and is the relative ratio (molar ratio) of the amounts of the respective constituent monomers of the obtained polyester resin and its weight%.
[ Production of polyester resin (A-1) ]
To a reaction vessel equipped with a thermometer, a stirrer, a rectifying column and a nitrogen inlet tube, 263.7 parts (1.5872 mol) of isophthalic acid (IPA) as a polycarboxylic acid, 3.1 parts (0.0161 mol) of trimellitic anhydride (TMAn), 105.0 parts (0.3221 mol) of ethylene oxide of about 2 mol adduct "NEWPOL BPE-20" (BPE-20) (Sanyo chemical industry Co., ltd.), 65.0 parts (1.0472 mol) of Ethylene Glycol (EG), 234.5 parts (0.4431 mol) of dimer alcohol "PRIPOL 2033" (P2033) (CRODA Co., ltd.), 62.9 parts (0.6039 mol) of neopentyl glycol (NPG), and 0.1 part of tetrabutyltitanate as a catalyst were charged, and an esterification reaction was carried out at 270℃for 1.5 hours after a lapse of 2.5 hours until the internal temperature reached 270 ℃.
Next, 0.1 part of tetrabutyl titanate as a catalyst was added thereto, and the inside of the system was depressurized to 2.5hPa, and polymerization was carried out over 2 hours.
Thereafter, the internal temperature was lowered to 230℃and 15.8 parts (0.0822 mol) of trimellitic anhydride (TMAn) was added thereto, followed by depolymerization at 230℃for 1 hour to obtain a polyester resin (A-1).
[ Production of polyester-based resin (A-2 to 8, A' -1 to 2) ]
Polyester resins (A-2 to 8 and A' -1 to 2) were obtained in the same manner as in A-1 except that the resin composition was changed as shown in Table 3-1.
The resin composition (structural unit derived from the component) and the physical properties of the obtained polyester resin are shown in tables 3 to 2. In Table 3-1, the abbreviations are as follows.
"NDCM": naphthalene dicarboxylic acid dimethyl ester
"IPA": isophthalic acid
"DMI": dimethyl isophthalate
"P1009": dimer acid "PRIPOL 1009" (manufactured by CRODA Co.)
"TMAn": trimellitic anhydride
"BPEF": diphenoxyethanol fluorene
"BPE-20": about 2 mol adduct "NEWPOL BPE-20" of bisphenol A ethylene oxide (Sanyo chemical industry Co., ltd.)
"EG": ethylene glycol
"NPG": neopentyl glycol
"1.4BG":1, 4-butanediol
"1.6HG":1, 6-hexanediol
"1.10DG":1, 10-decanediol
"P2033": dimer alcohol "PRIPOL 2033" (manufactured by CRODA Co., ltd.)
[ Table 3-1]
[ Table 3-2]
< Curing agent >
As a curing agent, the following polyepoxide compound was prepared.
Polyepoxide compound (B-1): phenol novolac type epoxy resin "YDPN-638" (manufactured by Nitro iron chemical & materials Co., ltd.) (WPE=177 (g/eq))
Polyepoxide compound (B-2): glycidyl Ether type Special multifunctional epoxy resin "jER-1031S" (Mitsubishi chemical Co., ltd.) (wpe=200 (g/eq))
Polyepoxide compound (B-3): triglycidyl Parafidol "jER-630" (manufactured by Mitsubishi chemical corporation) (wpe=96 (g/eq))
< Production of adhesive composition >
Using the polyester resin and the curing agent obtained above, an adhesive composition was produced as follows.
Example 3-1
The polyester resin (a-1) obtained above was diluted with a toluene/cyclohexane=4/1 (weight ratio) mixed solvent to a solid content concentration of 50%, 10 parts of the polyepoxide compound (B-1) (solid content) was mixed with the polyester resin (a-1) solution (100 parts by solid content), and the mixture was diluted, stirred and mixed with a toluene/cyclohexane=4/1 (weight ratio) mixed solvent to a solid content of 50%, whereby an adhesive composition was obtained.
Examples 3-2 to 3-4 and comparative examples 3-1 to 3-2
In example 3-1, an adhesive composition was obtained in the same manner as in Table 3-3 except that the resin composition was set as shown in Table 3.
The adhesive composition thus obtained was evaluated as shown below, and the results are shown in tables 3 to 3.
< Preparation of laminate >
The adhesive composition prepared above was applied to a polyimide film "KAPTON 200H" (manufactured by eastern dupont) having a thickness of 50 μm by an applicator, and then dried at 120 ℃ for 5 minutes to form an adhesive layer having a dry film thickness of 25 μm. Next, (1) a rolled copper foil having a thickness of 30 μm or (2) a polyimide film "KAPTON 200H" having a thickness of 50 μm was laminated on the adhesive layer surface of the polyimide film with an adhesive layer (lamination condition: 170 ℃ C., 0.2MPa, feed speed: 1.5 m/min), followed by heat treatment in an oven at 160 ℃ C. For 4 hours to cure the laminate, thereby obtaining each laminate.
For convenience, the laminate (polyimide film/adhesive layer/rolled copper foil) laminated with the rolled copper foil was designated PI/Cu.
[ Initial adhesion ]
The laminate obtained above was cut into 1cm wide pieces and used as test pieces. The test piece was fixed to a glass plate having a thickness of 2mm using a double-sided tape, and the tensile peel strength (peel speed: 50mm/min, peel angle: 180 °) of the test piece was measured using a peel tester at 23℃under 50% RH. The evaluation criteria are as follows.
And (3) the following materials: 12N/cm or more
O: 9N/cm or more and less than 12N/cm
Delta: 6N/cm or more and less than 9N/cm
X: less than 6N/cm
[ Durability to damp-heat ]
The PI/Cu test piece was placed in a constant temperature and humidity machine at 85 ℃ and 85% rh, taken out after a predetermined time, allowed to stand in an environment at 23 ℃ and 50% rh for one night, and then subjected to the same operation as the initial adhesion to measure the tensile peel strength. The percentage of the adhesive force after the wet heat treatment to the initial adhesive force was set as "maintenance rate".
The absolute value of the adhesive force was evaluated using the same evaluation criterion as the initial adhesive force.
The maintenance rate of the adhesive force was evaluated based on the following evaluation criteria.
And (3) the following materials: the maintenance rate is more than 80 percent
O: the maintenance rate is more than 60% and less than 80%
Delta: the maintenance rate is more than 40% and less than 60%
X: the maintenance rate is less than 40 percent
[ Gel fraction ]
The polyimide film with an adhesive layer obtained above was cured by heat treatment at 160℃for 4 hours, and then cut into a size of 4 cm. Times.4 cm. The resultant was wrapped with a 200 mesh SUS-made metal mesh, and immersed in methyl ethyl ketone at 23℃for 24 hours, whereby the percentage of the weight of the insoluble adhesive component remaining in the metal mesh relative to the weight of the adhesive before immersion was set as a gel fraction.
[ Tables 3-3]
Based on the results of tables 3-1 to 3-3, the polyester resins (A-1) to (A-8) of production examples 3-1 to 3-8 satisfying the conditions of the present invention were excellent in low dielectric constant and low dielectric loss tangent, in particular low dielectric loss tangent, and the adhesive compositions of examples 3-1 to 3-4 obtained by using them were excellent in initial adhesion after curing and further in long-term durability under a hot and humid environment.
On the other hand, the polyester resin (A' -1) of comparative production example 3-1 was inferior in low dielectric loss tangent, and the cured initial adhesion and further long-term durability under hot and humid environment of comparative example 3-1 obtained by using the same were also inferior. The polyester resin (A' -2) of comparative production example 3-2 was inferior in terms of low dielectric constant and low dielectric loss tangent.
The above-described embodiments are merely illustrative examples and are not to be construed as limiting the invention. Meaning that various modifications which are apparent to those skilled in the art are within the scope of the invention.
Industrial applicability
The adhesive composition of the present invention is an adhesive composition containing a polyester resin, and exhibits the effect of excellent long-term durability in a hot and humid environment and high adhesion. The adhesive composition of the present invention is particularly suitable for an adhesive used for producing a laminate of metal and plastic, for example, an adhesive used for producing a flexible laminate such as a flexible copper-clad laminate and a flexible printed board, a coverlay, a bonding sheet, and the like.

Claims (16)

1. An adhesive composition for a flexible printed circuit board, which is characterized by comprising a polyester resin (A1), wherein the polyester resin (A1) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyalcohol, the polyester resin (A1) comprises at least 1 selected from the group consisting of a dimer acid which is the polycarboxylic acid and a dimer alcohol which is the polyalcohol, the total content (alpha+beta) of the dimer acid relative to the whole polycarboxylic acid and the content (beta) of the dimer alcohol relative to the whole polyalcohol is more than 5 mol%,
The molar ratio (beta)/(alpha+beta) of the content (beta) of the dimer acid to the total content (alpha+beta) of the dimer alcohol is 0.6 or more,
The polyester resin (A1) satisfies the following conditions:
[1] the concentration of ester bonds is below 7 mmol/g;
[2] the acid value is more than 3 mgKOH/g;
[3] the glass transition temperature (Tg) is-5 ℃ or higher.
2. The adhesive composition for flexible printed circuit boards according to claim 1, wherein the polyester resin (A1) contains an aromatic polycarboxylic acid as a polycarboxylic acid, and the content of the aromatic polycarboxylic acid is 25 mol% or more based on the entire polycarboxylic acid.
3. The adhesive composition for flexible printed circuit boards according to claim 1 or 2, wherein the polyester resin (A1) has a carboxyl group in a side chain.
4. The adhesive composition for flexible printed circuit boards according to claim 1 or 2, wherein the polyester resin (A1) contains a bisphenol skeleton-containing monomer as the polyol, and the content of the bisphenol skeleton-containing monomer relative to the entire polyol is 10 mol% or more.
5. An adhesive composition for a flexible printed circuit board, which is characterized by comprising a polyester resin (A2), wherein the polyester resin (A2) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyalcohol, the polyester resin (A2) comprises at least 1 selected from the group consisting of a dimer acid which is the polycarboxylic acid and a dimer alcohol which is the polyalcohol, the total content (alpha + beta) of the dimer acid relative to the whole polycarboxylic acid and the content (beta) of the dimer alcohol relative to the whole polyalcohol is more than 5 mol%,
The molar ratio (beta)/(alpha+beta) of the content (beta) of the dimer acid to the total content (alpha+beta) of the dimer alcohol is 0.6 or more,
The polyester resin (A2) satisfies the following conditions:
[I] The polycarboxylic acid contains more than 25 mol% of aromatic polycarboxylic acid;
[ II ] the polycarboxylic acid contains a polycarboxylic acid (x 1) having 3 or more members and having 0 or 1 acid anhydride group number;
[ III ] the concentration of ester bonds is 7 mmol/g or less;
[ IV ] the acid value is 3mgKOH/g or more.
6. The adhesive composition for flexible printed circuit boards according to claim 5, wherein the glass transition temperature of the polyester resin (A2) is-5 ℃ or higher.
7. The adhesive composition for flexible printed circuit boards according to claim 5 or 6, wherein the polyester resin (A2) is a polyester resin obtained by a depolymerization step using a polycarboxylic acid (x 1).
8. The adhesive composition for flexible printed circuit boards according to claim 5 or 6, wherein the polyester resin (A2) contains a bisphenol skeleton-containing monomer as the polyol, and the content of the bisphenol skeleton-containing monomer relative to the entire polyol is 10 mol% or more.
9. An adhesive composition for flexible printed circuit boards, which is characterized by comprising a polyester resin (A3), wherein the polyester resin (A3) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol,
The polyester resin (A3) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyalcohols,
The ratio (beta)/(alpha+beta) of the content (beta) of the dimer alcohol to the total content (alpha+beta) of the dimer acid to the content (beta) of the dimer alcohol to the total content (alpha+beta) of the polycarboxylic acid is 0.6 or more,
The polyester resin (A3) has a glass transition temperature (Tg) of-5 ℃ or higher and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
10. An adhesive composition for flexible printed circuit boards, which is characterized by comprising a polyester resin (A4), wherein the polyester resin (A4) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol,
The polyester resin (A4) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyalcohols,
The ratio (beta)/(alpha+beta) of the content (beta) of the dimer alcohol to the total content (alpha+beta) of the dimer acid to the content (beta) of the dimer alcohol to the total content (alpha+beta) of the polycarboxylic acid is 0.6 or more,
The polyester resin (A4) has an acid value of 3mgKOH/g or more and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
11. An adhesive composition for flexible printed circuit boards, which is characterized by comprising a polyester resin (A5), wherein the polyester resin (A5) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol,
The polyester resin (A5) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyalcohols,
The ratio (beta)/(alpha+beta) of the content (beta) of the dimer alcohol to the total content (alpha+beta) of the dimer acid to the content (beta) of the dimer alcohol to the total content (alpha+beta) of the polycarboxylic acid is 0.6 or more,
The polyester resin (A5) has a glass transition temperature (Tg) of-5 ℃ or higher, an acid value of 3mgKOH/g or higher, and a dielectric loss tangent (alpha) of 0.005 or less at 10GHz in an atmosphere of a relative humidity of 50% RH at a temperature of 23 ℃.
12. An adhesive composition for flexible printed circuit boards, which is characterized by comprising a polyester resin (A6), wherein the polyester resin (A6) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol,
The polyester resin (A6) contains at least 1 selected from the group consisting of dimer acids as the polycarboxylic acids and dimer alcohols as the polyalcohols,
The ratio (beta)/(alpha+beta) of the content (beta) of the dimer alcohol to the total content (alpha+beta) of the dimer acid to the content (beta) of the dimer alcohol to the total content (alpha+beta) of the polycarboxylic acid is 0.6 or more,
The dielectric loss tangent (alpha) of the polyester resin (A6) at 10GHz under the conditions of the temperature of 23 ℃ and the relative humidity of 50% RH is less than 0.003.
13. The adhesive composition for flexible printed circuit boards according to any one of claims 1, 5, and 9 to 12, further comprising a polyepoxide compound (B).
14. An adhesive for a flexible printed circuit board, which is obtained by curing the adhesive composition for a flexible printed circuit board according to any one of claims 1 to 13.
15. A flexible printed circuit board, which is obtained by using the adhesive for a flexible printed circuit board according to claim 14.
16. An adhesive composition comprising a polyester resin (A1), wherein the polyester resin (A1) comprises a structural unit derived from a polycarboxylic acid and a structural unit derived from a polyhydric alcohol, wherein the polyester resin (A1) comprises at least 1 selected from the group consisting of a dimer acid which is the polycarboxylic acid and a dimer alcohol which is the polyhydric alcohol, and wherein the total content (alpha + beta) of the dimer acid relative to the whole polycarboxylic acid and the total content (alpha + beta) of the dimer alcohol relative to the whole polyhydric alcohol is 5 mol% or more,
The molar ratio (beta)/(alpha+beta) of the content (beta) of the dimer acid to the total content (alpha+beta) of the dimer alcohol is 0.6 or more,
The polyester resin (A1) satisfies the following conditions, the content of the polyester resin (A1) in the polyester resin exceeds 50 wt%,
[1] The concentration of ester bonds is below 7 mmol/g;
[2] the acid value is more than 3 mgKOH/g;
[3] the glass transition temperature (Tg) is-5 ℃ or higher.
CN202080073175.9A 2019-10-23 2020-09-18 Adhesive composition for flexible printed circuit board, adhesive for flexible printed circuit board, and flexible printed circuit board Active CN114555749B (en)

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