JP2010248380A - Adhesive composition, and adhesive sheet and coverlay film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesives composition, free from any halogen compound and other materials giving load to environment, that is excellent in storability in a semi-cured state and is excellent in adhesiveness, heat resistance, migration resistance, and flame resistance in a cured state, and to provide an adhesive sheet and coverlay film using the composition. <P>SOLUTION: The adhesive composition includes (A) a non-halogen-based epoxy resin, (B) a synthetic rubber, (C) a curing agent not having two or more thiol groups, (D) a polythiol compound having two or more thiol groups, (E) a curing accelerator, and (F) an inorganic filler. The adhesive sheet has a mold release base material and an adhesive layer comprising the adhesive composition prepared at least on one side of the mold release base material. The coverlay film has an electric insulation film and an adhesive layer comprising the adhesive composition prepared at least on one side of the electric insulation film. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an adhesive composition having excellent storage stability in a semi-cured state, excellent curability during heat processing, excellent adhesion after curing, heat resistance, migration resistance and flame retardancy, and the composition The present invention relates to an adhesive sheet and a cover lay film.

  In recent years, the development of the electronics field has been remarkable, and in particular, electronic devices for communication and consumer use have been reduced in size, weight and density, and the demand for these performances has become increasingly sophisticated. In response to such demands, a flexible printed wiring board (hereinafter abbreviated as FPC) has flexibility and withstands repeated bending, so that it can be mounted three-dimensionally in a narrow space, and electronic equipment. As a composite part with wiring, cable, connector function, etc., its application is expanding.

  The FPC is a circuit in which a circuit is produced by a conventional method on a flexible printed wiring board, and a coverlay film is bonded in such a way as to protect the circuit depending on the purpose of use. In recent years, electronic devices have been reduced in size, weight, circuit density, and the like, and there has been an increasing demand for multilayer flexible printed wiring boards in which four or more layers of flexible printed wiring boards are stacked. This multilayer flexible printed wiring board has a multilayer structure in which two or more single-sided copper foil FPCs or double-sided copper foil FPCs are laminated using an adhesive sheet. Properties required for these flexible printed wiring boards include adhesion durability, heat resistance, flexibility, folding resistance, migration resistance, flame resistance, and the like.

  Generally, a coverlay film used for FPC is an adhesive solution mainly composed of a thermosetting resin composition on at least one surface of an electrically insulating film having high heat resistance and excellent electrical and mechanical properties. Is applied and dried to a semi-cured state. Usually, a protective release sheet is bonded to the adhesive layer of the coverlay film, and is peeled off in use. The coverlay film is affixed to a surface on which a circuit is produced via an adhesive layer, and is used for the purpose of (1) circuit protection of FPC, (2) improvement of flexibility, and the like. Properties required for the coverlay film include high adhesive strength, heat resistance, flexibility, flame retardancy, and the like.

  The adhesive sheet used for FPC is a sheet having a semi-cured adhesive layer on at least one side of a release substrate. The adhesive sheet is used to form a multilayer FPC by stacking two or more single-sided copper foil FPCs or double-sided copper foil FPCs, or to bond a reinforcing plate or the like to the FPC, or both Be Properties required for the adhesive sheet include high adhesive strength, heat resistance, and the like.

  In addition, against the background of environmental problems in recent years, there is a tendency to suppress the use of halogen compounds for components mounted on electronic devices, and the use of bromine compounds that have been frequently used to make FPCs flame-retardant in the past. It has become difficult. Recently, as a flame retardant, a method of making a flame retardant by adding a phosphorus compound to an adhesive instead of a bromine compound has been widely used. As a result of a further increase in interest in environmental problems, it has become necessary to refrain from using environmentally hazardous substances other than halogen compounds and to substitute them with materials with less environmental burden.

  In addition to the above requirements, the adhesive composition used for the coverlay film and the adhesive sheet generally has a thermosetting resin as a main component, so that it has excellent storage stability during storage and at the time of processing. There is a demand for excellent thermosetting properties.

  As an adhesive composition, a thermosetting resin such as an epoxy resin is generally added with a thermoplastic resin for imparting flexibility, a rubber component or a combination thereof, a curing agent for an epoxy resin, and the like. used. The thermoplastic resin and rubber component must react with an epoxy resin thermosetting resin and be incorporated into a crosslinked structure so that heat resistance and adhesiveness are exhibited after the adhesive composition is cured. Those having a group are generally used.

  As the thermoplastic resin and the rubber component, acrylonitrile butadiene rubber (hereinafter referred to as NBR), acrylic rubber, ethylene / acrylic rubber, phenoxy resin, polyester resin and the like are generally used. Those having a carboxyl group, an epoxy group, an amino group or the like as a reactive functional group with a curable resin are used, and those having a carboxyl group are particularly frequently used. However, an adhesive composition containing such a thermoplastic resin having a reactive functional group, a rubber component or a combination thereof is inferior in storage stability due to the reaction between the epoxy resin and the reactive functional group during storage. There is a problem.

  As the above-mentioned adhesive composition, for example, an adhesive composition containing an epoxy resin, a curing agent, an aliphatic dimethylurea derivative, and NBR having a carboxyl group is known (Patent Document 1). Although this composition is excellent in preservability in a semi-cured state, there is a problem that it needs to be stored at a very low temperature of −10 ° C. in order to suppress the reaction between the epoxy resin and the carboxyl group in NBR. .

  In addition, a composition (Patent Document 2) containing an epoxy resin, a carboxyl group-modified rubber, a resol type phenol resin curing agent, an aromatic diamine curing agent, and a boron trifluoride complex as a curing accelerator, an epoxy resin, and a carboxyl group A composition (Patent Document 3) containing NBR, an aromatic diamine curing agent, and a boron trifluoride complex as a curing accelerator is known. Although these compositions have little deterioration in physical properties even when stored at room temperature and are excellent in preservability, they contain fluorine and boron that are regulated to be discharged into wastewater, thus reducing the environmental burden. Therefore, use should be avoided as much as possible.

JP 2001-348418 A JP 2001-164226 A JP 2002-76583 A

  Therefore, the present invention is excellent in preservability in a semi-cured state in spite of not using a halogen compound and other environmental load substances, and has excellent adhesion, heat resistance, migration resistance and flame retardancy after curing. An object is to provide an excellent adhesive composition, and an adhesive sheet and a coverlay film using the composition.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention have a composition containing a polythiol compound as a curing agent component together with other curing agents, which has excellent storage stability in a semi-cured state, and after curing. The present invention was completed by finding a cured product having excellent adhesion, heat resistance, migration resistance and flame retardancy.

That is, the present invention firstly
(A) non-halogen epoxy resin,
(B) synthetic rubber,
(C) a curing agent not having two or more thiol groups,
(D) a polythiol compound having two or more thiol groups,
An adhesive composition containing (E) a curing accelerator and (F) an inorganic filler is provided.

  Secondly, the present invention provides an adhesive sheet having a release substrate and an adhesive layer composed of the above composition provided on at least one surface of the release substrate. The adhesive sheet is obtained by applying the composition to a substrate having releasability.

  Thirdly, the present invention provides a coverlay film having an electrically insulating film and an adhesive layer made of the above composition provided on at least one surface of the electrically insulating film. The coverlay film is obtained by applying the composition onto an electrically insulating film.

  The composition of the present invention is excellent in preservability in a semi-cured state, has excellent adhesion, heat resistance, migration resistance and flame retardancy after curing, and further does not contain a halogen compound and other environmental load substances. is there. Therefore, the adhesive sheet and coverlay film produced using this composition are also excellent in adhesion, heat resistance, migration resistance and flame resistance, and do not contain halogen compounds and other environmentally hazardous substances.

<Adhesive composition>
The adhesive composition of this invention contains the said (A)-(F) component.
The usage method and usage form of the adhesive composition of the present invention are not limited in any way, but in one of the typical usage forms as an adhesive, the composition is sandwiched between two adherends in layers. It is used as a composition for adhering these adherends. A to-be-adhered body is not specifically limited, For example, the combination etc. of the copper foil and the electrically insulating film used for the coverlay film mentioned later are mentioned. Moreover, the composition of this invention is used also for manufacture of an adhesive sheet, a coverlay film, etc., for example.

  Hereinafter, the above components (A) to (F), other optional components, and the method for preparing the adhesive composition of the present invention will be described in more detail.

[(A) Non-halogen epoxy resin]
The non-halogen epoxy resin as component (A) is an epoxy resin that does not contain a halogen atom such as bromine in its molecule. This epoxy resin is not specifically limited, For example, you may contain silicone, urethane, a polyimide, polyamide, etc. Further, the skeleton may contain a phosphorus atom, a sulfur atom, a nitrogen atom, or the like.

  Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, or hydrogenated products thereof, phenol novolac type epoxy resins, cresol novolac type epoxy resins and other glycidyl ether type epoxy resins, Glycidyl ester epoxy resins such as glycidyl hexahydrophthalate and dimer acid glycidyl esters, glycidyl amine epoxy resins such as triglycidyl isocyanurate and tetraglycidyl diaminodiphenylmethane, linear aliphatics such as epoxidized polybutadiene and epoxidized soybean oil Epoxy resin, etc., preferably bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novo Click type epoxy resins. Examples of these commercially available products include jER (registered trademark) 1001 (manufactured by Japan Epoxy Resin), Epicron 830S (manufactured by DIC), jER517 (manufactured by Japan Epoxy Resin), EOCN103S (manufactured by Nippon Kayaku), jER828. (Made by Japan epoxy resin) etc. are mentioned.

  In addition, various phosphorus-containing epoxy resins in which phosphorus atoms are bonded using a reactive phosphorus compound are also effectively used when constituting a flame-retardant adhesive composition that does not contain a halogen. Specifically, for example, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (manufactured by Sanko Co., Ltd., trade name: HCA) is bonded to the phosphorus atom of this compound. A compound obtained by reacting a compound obtained by substituting the active hydrogen atom with hydroquinone (trade name: HCA-HQ, manufactured by Sanko Co., Ltd.) with the above-described epoxy resin is used. Examples of these commercial products include FX305 (manufactured by Toto Kasei Co., Ltd., phosphorus content: 3% by mass), EPICLON EXA9710 (manufactured by DIC, phosphorus content: 3% by mass), and the like.

  (A) The non-halogen-type epoxy resin of a component may be used individually by 1 type, or may use 2 or more types together.

[(B) Synthetic rubber]
The (B) component synthetic rubber is not particularly limited and can be used singly or in combination of two or more. Examples of the component (B) include acrylic rubber, NBR (that is, acrylonitrile-butadiene rubber), ethylene-acrylic rubber, styrene-butadiene rubber, butadiene-methylacrylate-acrylonitrile rubber, butadiene rubber, carboxyl group-containing acrylic resin, carboxyl Examples thereof include group-containing NBR, vinyl group-containing NBR, silicone rubber, urethane rubber, and polyvinyl butyral. Among these, carboxyl group-containing acrylic resins, carboxyl group-containing NBR, and carboxyl group-containing ethylene-acrylic rubber are preferable. Hereinafter, in particular, the carboxyl group-containing acrylic resin, the carboxyl group-containing NBR, and the carboxyl group-containing ethylene-acrylic rubber will be described.

<Carboxyl group-containing acrylic resin>
The carboxyl group-containing acrylic resin that can be used in the present invention has a glass transition temperature (Tg) of −40 to 30 ° C., and is mainly composed of an acrylate ester and a monomer having a small amount of carboxyl groups. Anything is acceptable. This glass transition temperature (Tg) is preferably -10 to 25 ° C. When the glass transition temperature is −40 to 30 ° C., the obtained adhesive composition has an appropriate tack and is excellent in handling properties. When the glass transition temperature is lower than −40 ° C., the obtained adhesive composition has a large tack and is inferior in handling properties. Moreover, when a glass transition temperature exceeds 30 degreeC, the adhesive composition obtained is inferior to adhesiveness. The glass transition temperature is measured by a differential scanning calorimeter (DSC).

  As for the weight average molecular weight of this acrylic resin, the measured value by gel permeation chromatography (GPC, standard polystyrene conversion) is preferably 100,000 to 1,000,000, and more preferably 300,000 to 850,000.

  The acrylic polymer can be prepared by ordinary solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc., but from the viewpoint of reducing ionic impurities that affect migration resistance as much as possible. Is more preferable.

  Preferable examples of the acrylic resin include (a) acrylic acid ester, methacrylic acid ester or a combination thereof, (b) acrylonitrile, methacrylonitrile or a combination thereof, and (c) three components of unsaturated carboxylic acid. An acrylic polymer obtained by polymerization is exemplified. The acrylic polymer may be a copolymer composed only of the components (a) to (c) or a copolymer containing other components.

(A) Acrylic acid ester, methacrylic acid ester, or a combination thereof (a) Acrylic acid ester, methacrylic acid ester or a combination thereof as a component imparts flexibility to the adhesive composition, (a) Specific compounds of the components include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylate-n-butyl, methacrylate-n-butyl, isobutyl acrylate, isobutyl methacrylate, acrylic Isopentyl acid, isopentyl methacrylate, acrylic acid-n-hexyl, methacrylic acid-n-hexyl, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, n-octyl acrylate, Methacryl Examples include acid-n-octyl, isononyl acrylate, isononyl methacrylate, acrylic acid-n-decyl, methacrylic acid-n-decyl, isodecyl acrylate, and isodecyl methacrylate. Among them, alkyl acrylates and alkyl methacrylates having 1 to 12, particularly 1 to 4 carbon atoms in the alkyl group are preferable. Each of the (a) component acrylic acid ester and methacrylic acid ester may be used alone or in combination of two or more.

  The amount of the component (a) is preferably 50 to 80% by mass in the component (B), and more preferably 55 to 75% by mass. When this amount is less than 50% by mass, the flexibility of the resulting composition may be impaired. Moreover, when it exceeds 80 mass%, the protrusion of the said composition may generate | occur | produce at the time of press work.

(B) Acrylonitrile, methacrylonitrile or a combination thereof (b) Component acrylonitrile, methacrylonitrile or a combination thereof imparts heat resistance, adhesiveness and chemical resistance to the adhesive sheet.

  The amount of the component (b) is preferably 15 to 45% by mass and more preferably 20 to 40% by mass in the component (B). When this amount is less than 15% by mass, the resulting cured product may be inferior in heat resistance. Moreover, when it exceeds 45 mass%, the softness | flexibility of an adhesive sheet may be impaired.

-(C) Unsaturated carboxylic acid (c) The unsaturated carboxylic acid of component (c) provides adhesion to the resulting composition, and at the same time serves as a crosslinking point during heat curing, and can be copolymerized with a carboxyl group. Specific examples of the compound include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. (C) The unsaturated carboxylic acid of a component may be used individually by 1 type, or may use 2 or more types together.

  (C) It is preferable that the quantity of a component is 2-10 mass% in (A) component, and 2-8 mass% is more preferable. If this amount is less than 2% by mass, the effect of crosslinking formation may be insufficient. On the other hand, when the amount exceeds 10% by mass, the composition is too cross-linked and poorly adapted to the adherend, which may cause bubbles and blisters during heat curing or solder bath treatment.

  As such a carboxyl group-containing acrylic resin, for example, under the trade name, Paracron ME-3500-DR (manufactured by Negami Kogyo Co., Ltd., glass transition temperature -35 ° C., weight average molecular weight 600,000, containing —COOH), Teisan Resin WS023DR ( Manufactured by Nagase ChemteX, glass transition temperature −5 ° C., weight average molecular weight 450,000, containing —OH and —COOH), Teisan Resin SG-280DR (manufactured by Nagase ChemteX, glass transition temperature −30 ° C., weight average molecular weight 900,000, -COOH-containing), Teisan resin SG-708-6DR (manufactured by Nagase ChemteX, glass transition temperature 5 ° C, weight average molecular weight 800,000, -OH and -COOH-containing). The said acrylic resin may be used individually by 1 type, or may use 2 or more types together.

<Carboxyl group-containing NBR>
As the carboxyl group-containing NBR that can be used in the present invention, for example, acrylonitrile and butadiene, the amount of acrylonitrile with respect to the total amount of acrylonitrile and butadiene is preferably 5 to 70% by mass, particularly preferably 10 to 50% by mass. Examples thereof include those obtained by carboxylating the molecular chain terminal of a copolymer rubber copolymerized so as to have a ratio, or a copolymer rubber of acrylonitrile and butadiene with a carboxyl group-containing monomer such as acrylic acid or maleic acid. For this carboxylation, for example, a monomer having a carboxyl group such as methacrylic acid can be used.

  The ratio of the carboxyl group in the carboxyl group-containing NBR (that is, the ratio of the monomer unit having the carboxyl group to the total monomers constituting the carboxyl group-containing NBR) is not particularly limited, but preferably 1 -10 mol%, particularly preferably 2-6 mol%. When this ratio satisfies the range of 1 to 10 mol%, the fluidity of the resulting composition can be controlled, so that good curability can be obtained.

  As such a carboxyl group-containing NBR, for example, Nipol 1072 (manufactured by Nippon Zeon Co., Ltd.) or PNR-1H (manufactured by JSR), which is a high purity product with a small amount of ionic impurities, can be used. High-purity carboxyl group-containing NBR is expensive and cannot be used in a large amount, but is effective in that it can simultaneously improve adhesion and migration resistance. The carboxyl group-containing NBR may be used alone or in combination of two or more.

<Carboxyl group-containing ethylene-acrylic rubber>
The carboxyl group-containing ethylene-acrylic rubber that can be used in the present invention includes an ethylene monomer unit and an acrylate monomer unit, a methacrylic acid ester monomer unit, or a combination thereof and a monomer having a carboxyl group. An ethylene-acrylic rubber composed of units can be used. Examples of the acrylate monomer unit include a methyl acrylate monomer unit, an ethyl acrylate monomer unit, and a butyl acrylate monomer unit. Examples of the methacrylate ester monomer unit include a methyl methacrylate monomer unit, an ethyl methacrylate monomer unit, and a butyl methacrylate monomer unit. Examples of the monomer unit having a carboxyl group include an acrylic acid monomer unit, a methacrylic acid monomer unit, and a maleic acid monomer unit.

  The ratio of the carboxyl group in the carboxyl group-containing ethylene-acrylic rubber (that is, the ratio of the monomer unit having a carboxyl group to the total monomer units constituting the carboxyl group-containing ethylene-acrylic rubber) is not particularly limited. However, Preferably it is 1-10 mol%, Most preferably, it is 2-6 mol%. When this ratio satisfies the range of 1 to 10 mol%, the fluidity of the resulting composition can be controlled, so that good curability can be achieved.

  Examples of such ethylene-acrylic rubber include Baymac G (manufactured by DuPont, containing —COOH) under the trade name. The said carboxyl group-containing ethylene-acrylic rubber may be used individually by 1 type, or may use 2 or more types together.

  Although the compounding quantity of (B) component is not specifically limited, Preferably it is 10-100 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 20-90 mass parts. When the component (B) satisfies the range of 10 to 100 parts by mass, the obtained flexible copper-clad laminate, coverlay film and adhesive sheet are more excellent in flame retardancy and peel strength from copper foil.

[(C) Curing agent not having two or more thiol groups]
The curing agent that does not have two or more thiol groups as component (C) is not particularly limited as long as it is normally used as a curing agent for epoxy resins. For example, polyamine curing agent, acid anhydride curing Agents, phenol resin type curing agents, etc., among them, from the viewpoint of not deteriorating the preservability in the semi-cured state of the resulting composition and the flame retardancy of the resulting cured product, aromatic polyamine curing agent, A curing agent having an aromatic ring in the molecular skeleton, such as a phenol resin type curing agent and an aromatic acid anhydride curing agent, is more preferable. Examples of polyamine curing agents include aliphatic amine curing agents such as diethylenetriamine, tetraethylenetetramine, and tetraethylenepentamine, alicyclic amine curing agents such as isophoronediamine, and aromatic amines such as diaminodiphenylmethane and phenylenediamine. Examples of such a curing agent include dicyandiamide, and as described above, an aromatic amine curing agent is particularly preferable. Examples of the acid anhydride curing agent include phthalic anhydride, pyromellitic acid anhydride, trimellitic acid anhydride, hexahydrophthalic anhydride, and the like. In particular, when the obtained composition is used for a coverlay film, an aromatic polyamine-based curing agent and a phenol resin-type curing agent are preferable because appropriate reactivity is required. (C) The hardening | curing agent of a component may be used individually by 1 type, or may use 2 or more types together.

  (C) The compounding quantity of a component becomes like this. Preferably it is 1-20 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 3-15 mass parts. When the blending amount is in the range of 1 to 20 parts by mass, the resulting composition is sufficiently cured, and the resulting cured product does not have an excessive degree of crosslinking, and tends to be excellent in heat resistance and adhesion. .

[(D) Polythiol compound having two or more thiol groups]
The polythiol compound having two or more thiol groups as the component (D) acts as a curing agent for the epoxy resin together with a curing agent not having two or more thiol groups as the component (C). The (D) component polythiol compound is a curing agent that reacts with the epoxy resin even at low temperatures. For example, when the solution of the adhesive composition of the present invention is applied to a substrate and dried by heating, the polythiol compound of component (D) reacts with the epoxy resin of component (A), and the adhesive composition is semi-cured. It becomes a state. This semi-cured state gives an adhesive composition with excellent storage stability. Therefore, the number of epoxy groups in the non-halogen epoxy resin as component (A) is a, the number of thiol groups in the polythiol compound having two or more thiol groups as component (D) is b, and component (C) When the number of active hydrogens in the curing agent not having two or more thiol groups is c, a / b is in the range of 2.0-30, and a / (b + c) is 1.0-10. It is preferable that it is the range of these. The a / b is more preferably in the range of 2.0 to 25, and still more preferably in the range of 2.0 to 20. The a / (b + c) is more preferably in the range of 1.0 to 8.0, and still more preferably in the range of 1.0 to 5.0.

  When a / b is in the range of 2.0 to 30, the obtained adhesive composition is particularly easy to obtain an appropriate semi-cured state, and the preservability in the semi-cured state and the heat resistance after curing are high. It tends to be excellent. When a / b is smaller than 2.0, the resulting adhesive composition tends to be in a state in which the curing reaction proceeds excessively when it is in a semi-cured state, and is inferior in adhesiveness and heat resistance after curing. Moreover, when a / b is larger than 30, the resulting adhesive composition tends to be in a state where the curing reaction is insufficient when it is in a semi-cured state and is poor in storage stability in the semi-cured state.

  When a / (b + c) is in the range of 1.0 to 10, the obtained adhesive composition is particularly easy to obtain an appropriate cured state, and has excellent heat resistance and adhesiveness after curing. It is easy to become. When a / (b + c) is smaller than 1.0, the resulting adhesive composition tends to be in a state where the curing reaction has progressed too much, and tends to be inferior in adhesiveness and heat resistance after curing. Moreover, when a / (b + c) is larger than 10, the resulting adhesive composition is likely to be insufficiently cured and poor in heat resistance after curing.

  The component (D) is not particularly limited as long as it is a polythiol compound having two or more thiol groups. Examples of the (D) component polythiol compound include 1,3,5-triazine-2,4,6-trithiol, 6-dibutylamino-1,3,5-triazine-2,4-dithiol, and 6-phenyl. Triazine polythiol compounds such as amino-1,3,5-triazine-2,4-dithiol; polyhydric alcohols such as ethylene glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, mercaptoacetic acid, β-mercaptopropionic acid, etc. Polythiol compounds which are ester compounds of mercapto organic acids such as ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (thioglycolate), trimethylolpropane tris (3-mercapto Lopionate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol poly (3-mercaptopropionate), etc .; 1,4-butanedithiol, 1,6-hexanedithiol, 1,10-decanedithiol Terminal thiol group-containing polyether; terminal thiol group-containing polythioether; terminal thiol group-containing polythiol compound obtained by reaction of an epoxy compound with hydrogen sulfide, and the like. Among them, a triazine polythiol compound, a polythiol compound that is an ester compound of a polyhydric alcohol and a mercapto organic acid, or a combination thereof is preferably used. Among the compounds specifically exemplified as the polythiol compound which is an ester compound of a polyhydric alcohol and a mercapto organic acid, ethylene glycol dithioglycolate is a polythiol compound having two thiol groups in the molecule, and ethylene glycol dithiol. Compounds other than glycolate are polythiol compounds having 3 or more thiol groups in the molecule. (D) The polythiol compound of a component may be used individually by 1 type, or may use 2 or more types together. For example, each of the triazine polythiol compound and the polythiol compound that is the ester compound may be used alone or in combination of two or more.

[(E) Curing accelerator]
The curing accelerator as component (E) includes a non-halogen epoxy resin as component (A) and a curing agent not having two or more thiol groups as component (C) and two or more thiol groups as component (D). It will not specifically limit if it accelerates | stimulates reaction with the polythiol compound which has. Examples of the curing accelerator include 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and ethyl isocyanate compounds of these compounds, 2-phenylimidazole, 2-phenyl-4-methylimidazole. Imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole; triphenylphosphine, tributylphosphine, tris (p-methylphenyl) phosphine, tris (p And triorganophosphines such as -methoxyphenyl) phosphine and tris (p-ethoxyphenyl) phosphine. (E) The hardening accelerator of a component may be used individually by 1 type, or may use 2 or more types together.

  (E) Although the compounding quantity of a component is not specifically limited, Preferably it is 0.1-10 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 0.1-5 mass parts, More preferably, it is 0.1-3 mass parts.

[(F) Inorganic filler]
The inorganic filler which is (F) component is a component mix | blended in order to improve the heat resistance and flame retardance of the hardened | cured material obtained. The inorganic filler is not particularly limited as long as it is conventionally used for a coverlay film, an adhesive sheet or the like. Specific examples of the inorganic filler include metal hydroxides such as aluminum hydroxide and magnesium hydroxide; metal oxides such as silicon dioxide, molybdenum oxide, and zinc molybdate from the point of acting also as a flame retardant aid. Among them, aluminum hydroxide, magnesium hydroxide and zinc molybdate are preferable. (F) The inorganic filler of a component may be used individually by 1 type, or may use 2 or more types together.

  Although the compounding quantity of (F) component is not specifically limited, Preferably it is 5-100 mass parts with respect to the total 100 mass parts of organic solid content in the adhesive composition of this invention, More preferably, it is 10-90 masses. Part. When the blending amount of the component (F) is in the range of 5 to 100 parts by mass, the obtained cured product tends to have excellent adhesion, heat resistance, and flame retardancy. The “organic solid content” is a non-volatile organic component that constitutes a cured product obtained by curing the adhesive composition of the present invention, and specifically, mainly the components (A) to (E). Among the components added in some cases (for example, other optional components described later), there may be components corresponding to this. Organic solvents are usually not included in organic solids.

[Other optional ingredients]
In addition to the above components (A) to (F), other optional components exemplified below may be added to the composition of the present invention as long as the object and effect of the present invention are not impaired.

-Phosphorus flame retardants Phosphorus flame retardants are useful for obtaining flame retardancy without using halogen. In order to obtain the composition of the present invention as a flame-retardant composition containing no halogen, a phosphorus-containing epoxy resin containing no halogen may be used as the component (A), and halogen and phosphorus as the component (A). A non-halogen-based epoxy resin that does not contain a phosphorus-containing flame retardant may be combined with the component (A) as another optional component, and a phosphorus-containing epoxy resin that does not contain a halogen as the component (A); A non-halogen epoxy resin containing no halogen and phosphorus may be used, and a phosphorus flame retardant may be combined with the component (A) as another optional component.

  Examples of phosphorus flame retardants include phosphazene compounds and phosphoric ester amide compounds. Since the phosphazene compound and the phosphoric ester amide compound contain a phosphorus atom and a nitrogen atom in the molecule, particularly high flame retardancy is obtained. In general, a phosphate ester may be used as a phosphorus-based flame retardant, but the phosphate ester is inferior in hydrolysis resistance and deteriorates the migration resistance of the resulting cured product. Absent.

  The higher the phosphorus content of the phosphorus-based flame retardant, the more desirable since the flame retardancy can be obtained with a small amount of phosphorus-based flame retardant. The specific phosphorus content is, for example, 8.0% by mass or more, more preferably 9.0% by mass or more, and particularly preferably 10.0% by mass or more. When the phosphorus content is less than 8.0% by mass, it may be necessary to increase the amount of phosphorus-based flame retardant added to impart flame retardancy to the resulting cured product. And at least one of the heat resistance is not preferable.

Organic solvent The composition of the present invention is prepared using the above-mentioned components (A) to (F) and components added as necessary in the absence of a solvent, and it is used as an adhesive sheet, a coverlay film and a flexible copper-clad laminate. Although it may be used for the production of a plate, it may be dissolved or dispersed in an organic solvent, and the composition may be prepared and used as a solution or dispersion (hereinafter simply referred to as “solution”). Examples of the organic solvent include N, N-dimethylacetamide, methyl ethyl ketone, N, N-dimethylformamide, cyclohexanone, N-methyl-2-pyrrolidone, toluene, methanol, ethanol, isopropanol, acetone, and the like. N-dimethylacetamide, methyl ethyl ketone, N, N-dimethylformamide, cyclohexanone, N-methyl-2-pyrrolidone, toluene, particularly preferably N, N-dimethylacetamide, methyl ethyl ketone, and toluene. These organic solvents may be used alone or in combination of two or more.

(Preparation of composition)
In the adhesive composition of the present invention, the components (A) to (F) and the organic solvent and other optional components added as necessary are mixed using, for example, a pot mill, a ball mill, a homogenizer, a super mill, or the like. Can be prepared.

<Coverlay film>
The said composition can be used for manufacture of a coverlay film. Specifically, for example, a cover lay film having an electrically insulating film and an adhesive layer made of the above composition provided on at least one surface of the electrically insulating film can be mentioned. The manufacturing method will be described below.

  A solution of the adhesive composition of the present invention prepared by mixing required components and an organic solvent in advance is applied to an electrically insulating film using a reverse roll coater, a comma coater or the like. The electrically insulating film coated with the solution is passed through an in-line dryer, and dried by removing the organic solvent at 80 to 160 ° C. over 2 to 10 minutes to obtain a semi-cured state. Next, a cover lay film is obtained by pressure bonding and laminating this semi-cured adhesive layer with a release substrate functioning as a protective layer of the adhesive layer using a roll laminator. The release substrate is peeled off when the coverlay film is used. The “semi-cured state” means a state in which the composition has dried and partially, in other words, a state in which the curing reaction has progressed incompletely.

  The thickness of the adhesive layer of the coverlay film after drying is usually 5 to 45 μm, preferably 5 to 35 μm.

-Electrical insulating film The said electrical insulating film will not be specifically limited if normally used for a flexible copper clad laminated board and a coverlay film. Specifically, for example, based on polyimide film, aramid film, polyethylene terephthalate film, polyethylene naphthalate film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, glass fiber, aramid fiber, polyester fiber, etc. Then, it is impregnated with epoxy resin, acrylic resin, or the like that becomes a matrix, and is made into a film or sheet and bonded to copper foil, etc., and the heat resistance and dimensional stability of the resulting coverlay film From the viewpoints of mechanical properties and the like, particularly preferably, a low-temperature plasma-treated polyimide film or a corona-treated aramid film can be suitably used. As a polyimide film, what is normally used for a coverlay film should just be used. The electrical insulating film may be of any thickness as required, but is preferably 7.5 to 50 μm.

・ Release substrate (protective layer)
The release substrate is not particularly limited as long as it is a film-like material that protects the adhesive layer and can be peeled from the adhesive layer without damaging the form as necessary. For example, polyethylene (PE) film, polypropylene (PP) film, polymethylpentene (TPX) film, plastic film such as polyester film subjected to release treatment; PE film, polyolefin film such as PP film, TPX film, release Examples include release paper obtained by coating a treated polyester film on one or both sides of a paper material.

<Adhesive sheet>
The said composition can be used for manufacture of an adhesive sheet. Specifically, for example, an adhesive sheet having an adhesive layer made of the composition and a release substrate that covers the adhesive layer and functions as a protective layer can be mentioned. As the release substrate, those described as the protective layer of the coverlay film can be used. Hereinafter, the manufacturing method of the adhesive sheet of this invention is demonstrated.

  A solution of the adhesive composition of the present invention prepared by mixing required components and an organic solvent in advance is applied to a release substrate using a reverse roll coater, a comma coater or the like. The release substrate coated with the solution is passed through an in-line dryer and dried by removing the organic solvent at 80 to 160 ° C. over 2 to 10 minutes to obtain a semi-cured state. Next, the semi-cured adhesive layer is pressure-bonded to another release substrate using a roll laminator and laminated. In this way, an adhesive sheet is obtained.

  The adhesive sheet and coverlay film of the present invention can be used to produce an FPC according to a conventional method. In the FPC manufacturing process, the semi-cured adhesive layer may be completely cured each time one or both of the adhesive sheet and the coverlay film are bonded together, or after the final FPC configuration is assembled, It may be cured. The adhesive layer in the semi-cured state in the adhesive sheet and the coverlay film of the present invention can be completely cured by heating at 140 to 180 ° C. for 40 to 120 minutes under a pressure of 1 to 5 MPa, for example.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, these Examples do not limit this invention at all. The components (A) to (F) and other optional components used in the examples are specifically as follows. In addition, the unit of the numerical value which shows the compounding ratio in a table | surface is a "mass part."

<Adhesive composition components>
(A) Non-halogen epoxy resin (1) jER1001 (trade name) (manufactured by Japan Epoxy Resin, epoxy equivalent: 450-500)
(2) jER828 (trade name) (manufactured by Japan Epoxy Resin, epoxy equivalent: 184-194)
(3) EPICLON EXA9710 (trade name) (manufactured by DIC, epoxy equivalent: 475, phosphorus content: 3% by mass)
・ (B) Synthetic rubber (1) Baymac G (trade name) (manufactured by DuPont, carboxyl group-containing ethylene-acrylic rubber)
(2) Nipol 1072 (trade name) (manufactured by Nippon Zeon, carboxyl group-containing NBR)
(C) Curing agent not having two or more thiol groups (1) 4,4′-diaminodiphenyl sulfone (DDS)
(D) Polythiol compound having two or more thiol groups (1) 1,3,5, -triazine-2,4,6-trithiol (hereinafter abbreviated as TTT)
(2) Pentaerythritol tetrakis (3-mercaptopropionate) (hereinafter abbreviated as PTM)
・ (E) Curing accelerator (1) 2E4MZ (trade name) (made by Shikoku Kasei Kogyo Co., Ltd., imidazole curing accelerator)
・ (F) Inorganic filler (1) Aluminum hydroxide (made by Showa Denko)
(2) Zinc molybdate (manufactured by Nippon Inorganic Chemical Industry)
・ Phosphorus flame retardant (optional component)
(1) SP-703 (trade name) (manufactured by Shikoku Chemicals, phosphoric ester amide, phosphorus content: 10% by mass)

<Characteristics of coverlay film>
[Example 1]
-Preparation of adhesive composition The components of the adhesive composition were mixed in the proportions shown in the column of Formulation Example 1 in Table 1, and the resulting mixture had a mass ratio of methyl ethyl ketone / toluene / N, N-dimethylacetamide of 10 / By adding a 10/1 mixed solvent, the total concentration of the organic solid component (that is, the components (A) to (E) and the phosphorus flame retardant) and the inorganic solid component (that is, the component (F)) is 35 masses. % Dispersion was prepared.

-Production of coverlay film The above dispersion was applied to the surface of polyimide film A (trade name: Kapton, Toray DuPont, thickness: 25 μm) with an applicator so that the thickness after drying was 25 μm. A coverlay film was prepared by drying the composition in a blowing oven at a temperature of 10 ° C. for a semi-cured state.

[Examples 2 to 4]
Example 1 except that the components of the adhesive composition in Example 1 were mixed in the proportions shown in the respective columns of Formulation Examples 2 to 4 in Table 1 instead of being mixed in the proportions shown in the columns of Formulation Example 1 in Table 1. A coverlay film was produced in the same manner.

[Comparative Examples 1-4]
Example 1 except that the components of the adhesive composition in Example 1 were mixed in the proportions shown in each column of Comparative Formulation Examples 1 to 4 in Table 1 instead of being mixed in the proportions shown in the column of Formulation Example 1 in Table 1. A coverlay film was produced in the same manner as described above.

[Measurement]
About the produced cover-lay film, characteristics, such as peeling strength, were measured according to the following measuring method 1, migration resistance was measured according to the following measuring method 2, and preservability was measured according to the following measuring method 3. The results are shown in Table 2.

[Measurement method 1]
1-1. Peel strength In accordance with JIS C6471, the glossy surface of rolled copper foil (manufactured by Nikko Materials, thickness: 18 μm) and the adhesive layer of the coverlay film are pressed (temperature: 160 ° C., pressure: 3 MPa, time: 60 minutes) to produce a press sample. The obtained press sample was cut into a size of 1 cm in width and 15 cm in length to obtain a test piece. The polyimide film surface of the test piece is fixed, and the minimum value of the force required to peel the copper foil at a speed of 50 mm / min in the direction of 90 degrees with respect to the polyimide film surface is measured at 25 ° C. It was shown as peel strength.

1-2. Solder heat resistance (normal condition, moisture absorption)
-Under normal conditions: A test piece was produced by cutting a press sample produced in the same manner as in the above measurement method 1-1 into a 25 mm square. The test piece was floated on a 300 ° C. solder bath for 30 seconds. When the test piece did not swell, peel, or discolor, it was evaluated as “good” (indicated by a circle in Table 2), and when the test piece swelled, peeled, or discolored, It was evaluated as “bad” (indicated by × in Table 2).
-Under moisture absorption: A test piece prepared in the same manner as that for measuring solder heat resistance under normal conditions was allowed to stand for 24 hours in an atmosphere of 40 ° C and 90% relative humidity, and then the test piece was placed at 260 ° C. It floated on the solder bath for 30 seconds. A case where none of the test piece swells, peels off or discolors is evaluated as “good” (indicated by a circle in Table 2), and a case where at least one of the test piece swells, peels off or discolors occurs. It was evaluated as “bad” (indicated by × in Table 2).

1-3. Flame retardance All the copper foil was removed by etching the pressed sample to prepare a sample. In accordance with UL94 VTM-0 flame retardancy standard, the flame retardancy of the sample was measured. A case where the sample exhibited flame retardancy satisfying the UL94 VTM-0 standard was evaluated as “good” (indicated by a circle in Table 2), and a case where the sample did not satisfy the UL94 VTM-0 standard was expressed as “ It was evaluated as “bad” (indicated by × in Table 2).

[Measurement method 2]
2-1. Migration resistance A comb-shaped circuit having a line width / space width = 50 μm / 50 μm is prepared on a two-layer single-sided flexible copper-clad laminate (manufactured by Shin-Etsu Chemical Co., Ltd., KN25SE12C, polyimide layer thickness 25 μm, copper foil thickness 12 μm). The adhesive layer of the coverlay film prepared above is combined with the flexible copper-clad laminate and the coverlay film by a press device (temperature: 160 ° C., pressure: 3 MPa, time: 60 minutes). Thus, a sample for evaluating the migration resistance of the coverlay film was produced.

  Under conditions of a temperature of 85 ° C. and a relative humidity of 85%, a DC voltage of 50 V was applied to both electrodes of the circuit of the sample for evaluation, and migration resistance was evaluated (migration tester, IMV, MIG-8600B). When a short circuit (reduction in resistance value) occurred between the conductors within 1,000 hours after voltage application, or when dendrite growth was observed after 1,000 hours, it was evaluated as “bad” (Table 2). In this case, the resistance value was maintained even after 1,000 hours, and the case where no dendrite was generated was evaluated as “good” (indicated by ○ in Table 2).

[Measurement method 3]
3-1. Preservability The coverlay film prepared above was left at 40 ° C. for 7 days. On the other hand, a circuit pattern for embedding test defined in JPCA-BM02 was prepared on a two-layer single-sided flexible copper-clad laminate (manufactured by Shin-Etsu Chemical Co., Ltd., KN25SR35A, polyimide layer thickness 25 μm, copper foil thickness 35 μm). An embedding evaluation sample was prepared by bonding the adhesive layer of the coverlay film after being left to stand on the circuit pattern. In accordance with JPCA-BM02, the embeddability evaluation sample was observed with a stereomicroscope with a magnification of about 10 times to confirm the presence or absence of bubbles between circuits. When bubbles were not confirmed between the circuits, the embedding property was evaluated as “good” (indicated by a circle in Table 2), and when bubbles were confirmed between the circuits, the embedding property was evaluated as “bad” (table). 2 indicates x).

<Characteristics of adhesive sheet>
Example 5
A dispersion was prepared in the same manner as in Example 1. Next, the dispersion was applied to the surface of the polyester film which had been subjected to a release treatment so that the thickness after drying was 25 μm with an applicator, and then it was dried in a blowing oven at 120 ° C. for 10 minutes. An adhesive sheet was prepared with the product in a semi-cured state.

[Examples 6 to 8]
In Example 5, an adhesive sheet was prepared in the same manner as in Example 5 except that the dispersion was prepared in the same manner as in Examples 2 to 4 instead of preparing the dispersion in the same manner as in Example 1.

[Comparative Examples 5 to 8]
In Example 5, instead of preparing the dispersion in the same manner as in Example 1, an adhesive sheet was prepared in the same manner as in Example 5 except that the dispersion was prepared in the same manner as in Comparative Formulation Examples 1 to 4, respectively.

[Measurement]
The characteristics of the prepared adhesive sheet were measured according to the following measuring method 4. The results are shown in Table 3.

[Measurement method 4]
4-1. Peel strength Through the adhesive layer separated from the polyester film of the adhesive sheet, polyimide film B (trade name: Apical, Kaneka, thickness: 75 μm) and polyimide film C (trade name: Apical, Kaneka, thickness: 25 μm), followed by bonding using a press device (temperature: 160 ° C., pressure: 3 MPa, time: 60 minutes) to produce a press sample. The sample was cut into a size of 1 cm in width and 15 cm in length to obtain a test piece. A polyimide film B (thickness: 75 μm) of the test piece was fixed, and a polyimide film C (thickness: 25 ° C.) The minimum value of the force required to peel 25 μm) at a rate of 50 mm / min in the direction of 180 degrees with respect to the surface of the polyimide film B was measured and indicated as the peel strength.

<Evaluation>
The compositions prepared in Formulation Examples 1 to 4 satisfy the requirements of the present invention, and the coverlay film and the adhesive sheet using the composition are storability, peel strength, solder heat resistance, flame retardancy, Excellent migration resistance.

  The compositions prepared in Comparative Formulation Examples 1 and 2 did not contain a polythiol compound having two or more thiol groups of the component (D), which is a requirement of the present invention, and had poor storage stability.

  The composition prepared in Comparative Formulation Example 3 did not contain a curing agent not having two or more thiol groups of the component (C), which is a requirement of the present invention, and was inferior in solder heat resistance.

  The composition prepared in Comparative Formulation Example 4 does not contain a polythiol compound having two or more thiol groups of the component (D), which is a requirement of the present invention, and is poor in storage stability. It did not contain the inorganic filler of component (F), which was a requirement, and was inferior in flame retardancy.

  The cured product obtained by curing the adhesive composition of the present invention, and the coverlay film and adhesive sheet using the composition are all stored, peel strength, solder heat resistance, flame resistance, and migration resistance. In addition, since it does not contain halogen compounds and other environmentally hazardous substances, it is expected to be applied to the production of flexible printed wiring boards that are environmentally friendly.

Claims (7)

(A) non-halogen epoxy resin,
(B) synthetic rubber,
(C) a curing agent not having two or more thiol groups,
(D) a polythiol compound having two or more thiol groups,
(E) A curing accelerator, and (F) an adhesive composition containing an inorganic filler.   When the number of epoxy groups in component (A) is a, the number of thiol groups in component (D) is b, and the number of active hydrogens in component (C) is c, a / b is 2.0 to 2.0. The adhesive composition according to claim 1, wherein the adhesive composition is in a range of 30 and a / (b + c) is in a range of 1.0 to 10.   The adhesive composition according to claim 1 or 2, wherein the component (D) is a triazine polythiol compound, a polythiol compound that is an ester compound of a polyhydric alcohol and a mercapto organic acid, or a combination thereof.   The composition which concerns on any one of Claims 1-3 which are pinched | interposed into a layer between two to-be-adhered bodies, and adhere | attach these adherends.   The adhesive sheet which has a mold release base material and the adhesive bond layer which consists of a composition of any one of Claims 1-3 provided in the at least single side | surface of this mold release base material.   The coverlay film which has an electrically insulating film and the adhesive bond layer which consists of a composition of any one of Claims 1-3 provided in the at least single side | surface of this electrically insulating film.   The coverlay film according to claim 6, wherein the electrically insulating film is a polyimide film.