JP4967485B2 - Adhesive composition and transparent laminate - Google Patents

Description

  The present invention relates to an adhesive composition. The adhesive composition is suitable for an adhesive for printed wiring boards, and in particular, a flexible printed circuit board, a coverlay film, and a semiconductor integrated circuit mounting tape (hereinafter referred to as “TAB”) called a TAB (tape automated bonding) system. It is suitable for an adhesive composition of a metal layer and a plastic film used for a touch panel substrate, an IC card, an IC tag substrate, an electronic paper substrate, a flexible display substrate, and the like.

  Flexible printed wiring boards are generally integrated by adhering a conductor such as copper foil or ITO film to a heat-resistant organic insulating film made of polyimide, liquid crystal polymer, etc., which is excellent in heat resistance and electrical insulation, via an adhesive. However, an epoxy resin adhesive is used as the adhesive because of its good adhesiveness. However, with the remarkable increase in wiring density and mounting density in recent years, there has been a demand for further improvements in the heat resistance, moisture resistance, adhesion, and workability of printed wiring boards. The TAB tape is basically the same as the flexible printed wiring board and basically has the same material structure and various required characteristics, but both are used properly according to the required characteristic level. Currently. In response to such market demands, printed boards using polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) have come to be used particularly in applications that require workability, cost, and moisture resistance. I came. These films are cheaper than polyimide and liquid polymer, and are excellent in transparency, so that they are easy to process during the production of printed circuit boards, and are excellent in moisture resistance compared to polyimide.

  By the way, when these bonds are made using an adhesive composed of an epoxy resin and a curing agent, a large distortion may occur in the cured adhesive due to the thermal cycle, and the joint may be destroyed. Attempts have been made to impart flexibility to the cured adhesive in order to absorb such internal strain and prevent the occurrence of internal stress. For example, a method of adding a synthetic rubber or the like to an adhesive composition is disclosed (see Patent Document 1). An adhesive composition in which a synthetic rubber is added to an epoxy resin is excellent in peel strength, but in heat resistance. It was not satisfactory.

  In order to solve these problems, the present applicant has proposed an epoxy resin composition comprising a methoxy group-containing silane-modified epoxy resin, an epoxy group-containing synthetic rubber, and a curing agent for epoxy resin. Although the thing has the favorable adhesiveness to a polyimide film, the adhesiveness to polyester films, such as PEN, was not enough. (See Patent Document 2)

  Therefore, the applicant of the present invention has been characterized by containing a methoxy group-containing silane-modified epoxy resin, a carboxyl group and / or a hydroxyl group, an acrylic polymer having a glass transition point of 20 ° C. or less, and a curing agent for epoxy resin, with repeated improvements. An adhesive composition was proposed. The adhesive composition exhibits excellent adhesion to not only polyimide films but also PEN and liquid crystal polymers, and is further superior to conventional epoxy resin adhesives that are adhesives for printed wiring boards. Although it showed heat resistance etc., in order to use for a display, an optical use, etc., what improved further transparency was calculated | required. (See Patent Document 3)

  JP-A-10-335768   JP 2003-246838 A   JP-A-2005-179408

  The present invention has an adhesive layer that has more excellent transparency and heat resistance, adhesiveness, moisture resistance, insulation, and the like compared to a conventional epoxy resin adhesive that is an adhesive for printed wiring boards. It is an object to provide an adhesive composition to be applied.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a methoxy group-containing silane-modified epoxy resin obtained by modifying a specific epoxy resin with a specific methoxysilane compound, a specific elastomer, and a curing agent for epoxy resin. It has been found that an adhesive composition that meets the above-mentioned purpose can be obtained by using a resin composition containing as an essential component, and the present invention has been completed.

  That is, the present invention has a methoxy group-containing silane-modified epoxy resin (A) obtained by subjecting a bisphenol-type epoxy resin (a-1) and a methoxysilane partial condensate (a-2) to a dealcoholization reaction, a carboxyl group, Acrylic polymer (B) having a glass transition point of 20 ° C. or less, an acid value of 2 to 10 (mgKOH / g), a number average molecular weight of 150,000 to 300,000, and a curing agent for epoxy resin (C) A laminate obtained by bonding polyethylene naphthalate or polyethylene terephthalate using the laminate adhesive composition, wherein the laminate has a haze value of 20% Concerning.

  The adhesive composition of the present invention is not only excellent in adhesiveness, heat resistance, moisture resistance, insulation, etc., but also excellent in transparency, and can be sufficiently used especially for optical applications. It is. Therefore, the adhesive composition according to the present invention is a metal used for flexible printed circuit boards, TAB tapes, touch panel substrates, IC cards, IC tag substrates, electronic paper substrates, flexible display substrates, electromagnetic wave shielding laminates, and the like. It is useful as an adhesive composition between a layer and a plastic film.

  The methoxy group-containing silane-modified epoxy resin (A) used in the present invention comprises a bisphenol-type epoxy resin (a-1) (hereinafter referred to as (a-1) component) and a methoxysilane partial condensate (a-2) (hereinafter referred to as (A-2) component). The component (a-1) is obtained by a reaction of bisphenols with a haloepoxide such as epichlorohydrin or β-methylepichlorohydrin. Examples of bisphenols include reaction products of phenol or 2,6-dihalophenol with aldehydes or ketones such as formaldehyde, acetaldehyde, acetone, acetophenone, cyclohexanone, and benzophenone, as well as oxidation of dihydroxyphenyl sulfide with peracid, Examples thereof include those obtained by etherification reaction between hydroquinones.

  The component (a-1) has a hydroxyl group that can undergo a demethanol reaction with the component (a-2). The hydroxyl group does not need to be contained in all molecules constituting the component (a-1), and may have a hydroxyl group as the component (a-1). Since the epoxy equivalent of the component (a-1) varies depending on the structure of the component (a-1), an epoxy equivalent having an appropriate epoxy equivalent can be appropriately selected and used depending on the application, but 350 to 1000 g / eq or less. Some are preferred. If it is less than 350 g / eq, the adhesiveness of the resulting adhesive layer tends to be low, and if it exceeds 1000 g / eq, the storage stability of the methoxy group-containing silane-modified epoxy resin tends to be low. Among these (a-1) components, bisphenol A type epoxy resins are particularly preferred because they are the most widely used and inexpensive.

As the component (a-2) constituting the component (A), an oligomer obtained by partially hydrolyzing and condensing methoxysilane generally used in a sol-gel method can be used. For example, it is represented by the general formula: R _p Si (OCH ₃ ) _4-p (wherein p represents an integer of 0 or 1, and R represents a lower alkyl group having 6 or less carbon atoms or a phenyl group). Examples include partial condensates of compounds. In addition, when p is 2-4, since three-dimensional crosslinking does not occur, desired heat resistance cannot be imparted to the finally obtained cured adhesive.

  Specific examples of the component (a-2) include a partial condensation product of tetramethoxysilane; methyltrimethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane. Examples thereof include partial condensates of trimethoxysilanes such as methoxysilane and mixtures thereof. Among these, partial condensates such as tetramethoxysilane and methyltrimethoxysilane, and mixtures thereof are preferable because of their high sol-gel curing rate.

  The component (a-2) may be appropriately selected from one or more of the above substances, but the average number of Si per molecule is preferably 3-12. When the average number of Si is less than 3, the amount of toxic methoxysilanes flowing out of the system together with the by-product alcohol during the dealcoholization reaction with the component (a-1) is not preferable. If it exceeds 12, the reactivity with the component (a-1) falls, and it takes a long time to obtain the desired component (A).

  In particular, as the component (a-2), the general formula:

  (In the formula, Me represents a methyl group, and the average number of repeating units of n is 3 to 8.) When the one containing 70% by weight or more of a methyltrimethoxysilane partial condensate represented by It is preferable in terms of moisture resistance and flexibility.

  (A) component used by this invention is obtained by the demethanol reaction of the said (a-1) component and (a-2) component. The proportion of the component (a-1) and the component (a-2) used is not particularly limited as long as the methoxy group remains in the component (A) to be obtained, but the component (a-2) It is preferable in terms of heat resistance and adhesion that the silica equivalent weight / (a-1) component weight (weight ratio) is in the range of 0.25 to 1.2. In addition, with respect to a general elastomer (B) (hereinafter referred to as component (B)), a cured film obtained only from component (a-1) and epoxy resin curing agent (C) (hereinafter referred to as component (C)). The refractive index of (a-2) is high, and when the weight of the component (a-2) in terms of silica / weight (weight ratio) of the component (a-1) increases, a cured film obtained only from the component (A) and the component (C) Since the refractive index of (B) decreases and approaches the refractive index of the component (B), the weight ratio is particularly preferably 0.50 or more because the choices of the component (B) that can be used are widened.

  The production of the component (A) is, for example, by charging the components (a-1) and (a-2), heating and distilling off the alcohol produced as a by-product or returning to the system by refluxing with a cooling tube. Done. The reaction temperature is about 50 to 130 ° C., preferably 70 to 110 ° C., and the total reaction time is about 1 to 15 hours. In order to prevent the polycondensation reaction of the component (a-2) itself, this reaction is preferably carried out under substantially anhydrous conditions.

  In the above demethanol reaction, a catalyst that does not open an epoxy ring among conventionally known catalysts can be used to promote the reaction. Examples of the catalyst include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium, and manganese. And metals such as oxides, organic acid salts, halides, and methoxides of these metals. Among these, organic tin and organic acid tin are particularly preferable, and specifically, dibutyltin dilaurate, tin octylate and the like are effective.

  The above reaction can be performed in a solvent or without a solvent. The solvent is not particularly limited as long as it is an organic solvent that dissolves the component (a-1) and the component (a-2) and is inert to them. Examples of such an organic solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone, esters such as ethyl acetate and butyl acetate, aromatics such as toluene and xylene, cellosolve acetate, methyl cellosolve acetate and the like. And an aprotic polar solvent such as dimethylformamide, ethers such as cellosolve, tetrahydrofuran and diethylene glycol dimethyl ether, alcohols such as isopropyl alcohol and n-butyl alcohol, and the like. Among these, those having a boiling point of 70 to 110 ° C. at normal pressure such as methyl ethyl ketone are particularly preferable for the following reasons. That is, the adhesive composition is formed by forming a B stage layer (adhesive sheet) on a base film such as PEN, laminating or hot pressing a conductor such as copper foil, and further heating to form a C stage layer ( This adhesive cured product) undergoes a manufacturing process. When heating after bonding the conductor, if a large amount of volatile matter (solvent, etc.) is generated, bubbles are generated between the conductor and the adhesive cured product. This is because problems such as irregularities on the conductor surface occur. From this, when producing the adhesive sheet, the residual amount of volatile components such as a solvent is reduced as much as possible, and the residual amount of volatile components in the cured residue of the C stage layer is adjusted to 5% by weight or less. Is preferred. When a solvent having a boiling point exceeding 110 ° C. is used, it is necessary to excessively increase the formation temperature of the adhesive sheet in order to reduce the residual ratio of the solvent. As a result, the interlayer adhesion between the subsequent C stage layer and the conductor Is not preferable because of a tendency to become insufficient. Moreover, when the boiling point of the solvent used is less than 70 ° C., it takes a long time for the demethanol reaction between the component (a-1) and the component (a-2), which is not preferable.

  The component (A) thus obtained is mainly composed of an epoxy resin in which the hydroxyl group in the component (a-1) is silane-modified, but the component (A) is not reacted with the component (a-1). Or an unreacted component (a-2) may be contained.

  The component (A) has in its molecule an methoxysilyl moiety derived from the component (a-2) and an epoxy group derived from a bisphenol type epoxy resin. The methoxysilyl moiety forms a cured product bonded to each other by evaporation of the solvent, heat treatment, or reaction with moisture (humidity). Such a cured product has fine gelled silica sites (high-order network structure of siloxane bonds). Therefore, the methoxy group contained in the component (A) preferably retains 60 mol% or more of the methoxyl group of the component (a-2) used. The epoxy group reacts with the component (C) described later.

  The component (B) used in the present invention has a carboxyl group, a glass transition point of 20 ° C. or less, an acid value of 2 to 10 (mgKOH / g), a number average molecular weight of 150,000 to 300,000, It is necessary to select a material that gives flexibility to the cured agent and does not generate a decomposition product at a solder melting temperature (230 to 260 ° C.) and has a strong adhesion to a transparent film such as PEN or PET.

By setting the glass transition temperature of the component (B) to −50 to 20 ° C., it becomes easy to mix with other components such as the component (A), so the amount of the solvent (D) used can be reduced. From the viewpoint of easy viscosity adjustment, it is particularly preferable to set the temperature to −50 to 0 ° C. because it is hardly affected by temperature such as seasonal factors. When the glass transition point exceeds 20 ° C., the flexibility of the cured adhesive is deteriorated, and the press temperature at the time of bonding is increased, which is not preferable.

In order to obtain adhesion to a transparent film such as PEN or PET, it has at least one functional group selected from the group consisting of a carboxyl group and a hydroxyl group, and is generally (1) acrylic acid An ester, an α-substituted acrylate ester as a main component, and a polymer containing at least one of the functional groups as a crosslinking point, or (2) at least one monomer having the functional group as the main component. Examples thereof include a polymer obtained by graft polymerization with a monomer as a component. Specifically, an epoxy group-containing monomer (B-) is added to a constituent component mainly composed of one of acrylic ester or α-substituted acrylic ester (B-1) (hereinafter referred to as component (B-1)). 2) (hereinafter referred to as (B-2) component), carboxyl group-containing monomer (B-3) (hereinafter referred to as (B-3) component), hydroxyl group-containing monomer (B-4) (hereinafter referred to as (B-4) And a monomer having at least one functional group selected from the group consisting of components)). Examples of the component (B-1) include monomers having no epoxy group, carboxyl group and hydroxyl group such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and octyl acrylate. Examples of the component (B-2) include glycidyl ethers such as vinyl glycidyl ether and allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate and the like which do not have a carboxyl group and a hydroxyl group other than the component (B-1). Examples of the component (B-3) include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride and the like which have no hydroxyl group other than the components (B-1) and (B-2). (B-4) Components other than (B-1) to (B-3), methacrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxypropyl, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, polyethylene glycol Examples include dimethacrylates of polyhydric alcohols such as dimethacrylate, alkoxy acrylates such as methoxymethyl acrylate, and the like. These can be used alone or in admixture of two or more. Furthermore, if necessary, other vinyl monomers such as vinyl chloride, vinylidene chloride, styrene, acrylonitrile, vinyl acetate and the like may be copolymerized.

  As (B) component used for this invention, an acid value needs to be 2-10 (mgKOH / g). When this range is exceeded, the compatibility with the component (A) deteriorates, a uniform adhesive composition cannot be obtained, and the transparency tends to decrease. Moreover, when it exceeds 10, it exists in the tendency for the water absorption of an adhesive composition and an electrical property to fall.

  Moreover, the number average molecular weight of the (B) component used for this invention needs to be 150,000-300,000. When this range is exceeded, compatibility with the component (A) deteriorates, a uniform adhesive composition cannot be obtained, and the transparency of the cured film obtained from the adhesive composition tends to deteriorate.

  In the present invention, it is important to reduce the refractive index difference between the cured film obtained from the component (A) and the component (C) and the component (B) for the purpose of obtaining an adhesive layer excellent in transparency. It is necessary to select an elastomer having a refractive index of 1.45 to 1.54. When the refractive index is 1.45 or less and 1.54 or more, the difference between the refractive index of the cured film obtained from the component (A) and the component (C) becomes large, so that haze is likely to occur in the adhesive layer. There is a strong tendency to lose transparency. In addition, as said (B) component, a commercially available thing can also be used as it is. As a commercially available acrylic polymer, the method which has Teisan resin SG-70L (brand name Nagase ChemteX Co., Ltd. product) etc. as a main component is mention | raise | lifted, for example.

  The component (B) used in the adhesive composition of the present invention is preferably dissolved in a solvent before being mixed with other components. (B) As a solvent which can be used for melt | dissolution of a component, the same thing as what was used at the time of manufacture of (A) component is mentioned. Considering the ease of mixing, it is preferable that the solid content is about 10 to 30% by weight and the viscosity is about 100 to 10000 mPa · s.

  (C) component used for this invention is not specifically limited, The phenol resin type hardening | curing agent which is a well-known hardening | curing agent for epoxy resins, a polyamine type hardening | curing agent, a polycarboxylic acid type hardening | curing agent, etc. can be used. Specifically, examples of the phenol resin-based curing agent include phenol novolak resin, cresol novolac resin, bisphenol novolak resin, poly p-vinylphenol, and the like, and examples of the polyamine-based curing agent include diethylenetriamine, triethylenetetramine, and tetraethylenepenta. Min, dicyandiamide, polyamidoamine (polyamide resin), ketimine compound, isophoronediamine, m-xylenediamine, m-phenylenediamine, 1,3-bis (aminomethyl) cyclohexane, N-aminoethylpiperazine, 4,4'-diamino Examples include diphenylmethane, 4,4'-diamino-3,3'-diethyldiphenylmethane, diaminodiphenylsulfone and the like, and polycarboxylic acid curing agents include phthalic anhydride, tetrahydroanhydride Taric acid, methyltetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalic anhydride, hexachloroendomethylenetetrahydrophthalic anhydride, methyl-3,6-endomethylenetetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, can give. Among these, it is preferable to use at least one selected from the group consisting of an aromatic amine and a novolak phenol resin because both pot life and low-temperature curing of the adhesive composition can be achieved. In addition, when (C) component used for the adhesive composition of this invention is solid at room temperature, it is preferable to make it melt | dissolve in a solvent before mixing with another component. (C) As a solvent which can be used for melt | dissolution of a component, the same thing as what was used at the time of manufacture of (A) component is mentioned. In addition, the adhesive composition of the present invention is preferably diluted with a solvent to adjust the viscosity depending on the coating conditions such as the type of coater. Examples of the diluting solvent include the same ones used in the production of the component (A).

The adhesive composition of the present invention is prepared by blending the above-described various essential components, that is, the component (A), the component (B), and the component (C). The blending ratio of the component (B) to the component (A) is 90 to 200 with respect to the curing residue of the component (A) from the viewpoint of transparency and interlayer adhesion between the cured adhesive and a transparent film such as a polyester film. Must be in weight percent. If the said mixture ratio is less than 90 weight%, the adhesiveness of the hardened layer with respect to a conductor will become inadequate, and a transparent adhesive hardened | cured material will not be obtained. Moreover, when it exceeds 200 weight%, there exists a tendency for heat resistance to fall. In addition, the hardening residue of (A) component is calculated | required as follows. That is, (A) component and 1 equivalent of triethylenetetramine are mixed, and about 1 g of the mixed solution is weighed into an aluminum cup (50 mm diameter) (weighing (i)), and this is continued at 100 ° C. for 1 hour. Dried at 200 ° C. for 2 hours, cured, reweighed (weighed (ii)), and calculated from the following equation.
Curing residue (%) = (weighing (ii) -triethylenetetramine weight) × 100 / weighing (i)

  The blending ratio of the component (C) is such that the functional group having active hydrogen in the component (C) is about 0.1 to 1.2 equivalents relative to 1 equivalent of the epoxy group present in the adhesive composition. Preferably there is.

  In addition, the adhesive composition contains an epoxy curing accelerator, accelerates the curing reaction between the epoxy resin and the curing agent, and cures the adhesive composition that is performed after bonding the base material such as copper foil. And the curing time can be shortened. For example, tertiary amines such as 1,8-diaza-bicyclo [5.4.0] undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol; 2 -Imidazoles such as methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole; Organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine; Tetraphenylphosphonium / tetraphenylborate, 2-ethyl-4-methylimidazole / tetraphenylborate, N-methylmorpholine / tetraphenylborate, etc. Such as boron salt can be mentioned. It is preferable to use the said hardening accelerator in the ratio of 0.05-5 weight% with respect to the hardening remainder of (A) component.

  In addition, since alcohol is generated in the sol-gel curing reaction of the methoxysilyl moiety, the curing after the epoxy group ring-opening / crosslinking reaction proceeds between the epoxy group in the component (A) and the component (C). When alcohol is generated, foaming or cracking may occur in the cured adhesive. Therefore, it is necessary to add a sol-gel curing accelerator such as an organotin catalyst, but the accelerator is complexed with a functional group such as a carboxylic acid or a hydroxyl group contained in the acrylic polymer. Pot life may be shortened. Therefore, it is preferable to use or use an aromatic amine that also acts as a sol-gel curing accelerator for the component (C).

  The composition of the adhesive composition of the present invention can be appropriately adjusted according to its use, but usually the silica equivalent weight in the cured adhesive obtained from the adhesive composition is 7 to 41% by weight. It is preferable to blend them as follows. In addition, when the equivalent weight is 15 to 25% by weight, the heat resistance of the adhesive cured product and the adhesion to the base material are excellent, which is particularly preferable. Here, the weight in terms of silica refers to the weight of silica obtained by subjecting the component (a-2) used in the production of the component (A) contained in the adhesive composition to a sol-gel curing reaction. As a method for adjusting the weight in terms of silica in the cured adhesive obtained from the adhesive composition, the blending ratio of the component (A), the component (B), and the component (C) is adjusted within the range of the ratio described above. In addition to the method of performing, there are a method of containing other solid components and a method of adding the component (a-2). Examples of such other solid components include bisphenol type epoxy resins (a-1), epoxy resins such as conventionally known novolak type epoxy resins and hydrogenated epoxy resins, and phenol resins. In particular, when the adhesive composition is used as an adhesive composition for a coverlay, 20 to 400% by weight of an epoxy resin is used with respect to the cured residue of the component (A) because it is necessary to fill the unevenness of the circuit. It is necessary to use it. If it is less than 20% by weight, the fluidity of the adhesive is insufficient and the circuit is not filled. If it exceeds 400% by weight, the heat resistance is lowered and the bleeding property tends to deteriorate. Examples of such epoxy resins include the same ones as (a-1) used during the production of the component (A), but those that are solid at room temperature are easier to handle as a coverlay film. .

  In the adhesive composition of the present invention, a mold release agent, a surface treatment agent, a flame retardant, a viscosity modifier, a plasticizer, an antibacterial agent, an antifungal agent, and the like, as long as the effects of the present invention are not impaired. You may mix | blend a leveling agent, an antifoamer, a coloring agent, a stabilizer, a coupling agent, etc.

  The adhesive composition thus obtained includes a flexible printed circuit board, a coverlay film and a TAB tape, a touch panel substrate, an IC card, an IC tag substrate, an electronic paper substrate, a flexible display substrate, and an electromagnetic wave shielding laminate. It can be used as an adhesive composition of a metal layer and a plastic film used for a body or the like.

  To obtain a flexible printed circuit board, cover lay film, TAB tape, touch panel substrate, IC card, IC tag substrate, electronic paper substrate, flexible display substrate, electromagnetic wave shielding laminate from the adhesive composition of the present invention The adhesive composition of the present invention is applied on a substrate film at a cured film thickness of about 5 to 50 μm, dried at 70 to 150 ° C. for about 30 seconds to 15 minutes, and then a metal foil such as copper foil is applied to 50 A method is used in which thermocompression bonding is performed at about -100 ° C., followed by after-curing at about 40-150 ° C. for about 1 to 3 hours and complete curing on the C stage. In stage B, the volatile content of the adhesive composition (solvent for production in component (A), methanol by-produced by sol-gel curing reaction of methoxysilyl moiety of component (A), solvent in adhesive composition) It is necessary to prevent the generation of bubbles in the subsequent C stage by reducing the residual rate of. In the case of the coverlay film, the production is completed when the adhesive composition is dried and cured on the base film to make the B stage. Later, the printed circuit board is 0.5 to 5 MPa, 80 to 150 ° C., 1 to 3 Used by hot pressing for about an hour.

  The substrate film to which the adhesive composition is applied is not particularly limited, and any known film can be used without limitation depending on the application, but for touch panel substrates, IC cards, IC tag substrates, and electronic papers. When light transmittance is particularly important as a laminate such as a substrate or a flexible display substrate, a colorless base film is preferably used, and a polyester film such as PEN or PET is particularly preferable. When heat resistance is particularly required as a laminate, such as a flexible printed circuit board, coverlay film, and TAB tape, it is possible to use a base material made of any one selected from the group consisting of PEN and polyimide. From the point of view, it is preferable.

  Moreover, as a metal foil, various well-known things can be used according to the use of the said laminated body. Specifically, gold foil, ITO foil, silver foil, copper foil, nichrome foil, aluminum foil and the like can be mentioned, but when used for printed wiring boards, TAB tapes, etc., copper foil, nichrome foil, aluminum foil are preferable. .

The cured product made from the adhesive composition of the present invention has heat resistance, adhesion, moisture resistance and insulation, and is particularly excellent in transparency. The adhesive layer of about 15 μm obtained from the adhesive composition usually has a solder heat resistance of 230 ° C. to 260 ° C., and the adhesion is, for example, PEN / PET as a base film, metal layer When an electrolytic copper foil is used, the peel strength is 9 N / cm or more. Further, the water absorption is usually 0.5% or less, and the moisture resistance is excellent. Especially in the solder heat resistance test after storage for 12 hours in the environment of temperature 80 ° C. and humidity 85%, which is usually evaluated for the above-mentioned use. Does not occur. Further, the volume resistance is usually 10 ¹³ Ω · cm or more, and the insulation is excellent. In the most important transparency, it is preferable that the haze value is usually 5% or less when the film thickness is 15 μm, and 10% or less when the film thickness is 500 μm. At this time, when a laminate in which an adhesive layer is provided on PEN or PET and PEN or PET is laminated on the adhesive layer is produced, an increase in haze value is suppressed, and the haze value is usually 20% or less.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In each example, “%” is based on weight unless otherwise specified.

Production Example 1 (Production of methoxy group-containing silane-modified epoxy resin (A-1))
In a reactor equipped with a stirrer, a condenser tube, and a thermometer, bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., trade name “JER1001”, epoxy equivalent 480 g / eq) (a-1) 800.0 g and MEK960 0.0 g was added and dissolved at 80 ° C. Furthermore, poly (methyltrimethoxysilane) (manufactured by Tama Chemical Co., Ltd., trade name “MTMS”, which is a partial condensate of methyltrimethoxysilane (CH ₃ Si (OCH ₃ ) ₃ ) and having an average number of Si of 3.5. -A ") (a-2) 605.0 g and 2.3 g of dibutyltin laurate as a catalyst were added and subjected to a demethanol reaction at 80 ° C for 5 hours to obtain an active ingredient (after curing) 50%, weight in terms of silica / bisphenol. Type epoxy resin (1) has a weight (weight ratio) of 0.51. A methoxy group-containing silane-modified epoxy resin (A-1) having an epoxy equivalent of 1400 g / eq was obtained. Moreover, it was confirmed by ¹ H-NMR that 87 mol% of the methoxy group of the partial condensate component of methyltrimethoxysilane was retained.

Production Example 2 (Production of methoxy group-containing silane-modified epoxy resin (A-2))
400.0 g of JER1001 (a-1) and 334.8 g of MEK were added to a reactor equipped with a stirrer, a condenser tube, and a thermometer, and dissolved at 80 ° C. Furthermore, poly (tetramethoxysilane) (manufactured by Tama Chemical Co., Ltd., trade name “Partial condensate of tetramethoxysilane (Si (OCH ₃ ) ₄ ) (a-2)) having an average number of Si of 4.0. MS-51 ") (429.1 g) and dibutyltin dilaurate (0.35 g) as a catalyst were added and subjected to a demethanol reaction at 80 ° C for 5 hours to obtain an active ingredient (after curing) of 50%, weight in terms of silica / bisphenol type epoxy resin ( A methoxy group-containing silane-modified epoxy resin (A-2) having a weight (weight ratio) of 1) of 0.55 and an epoxy equivalent of 1400 g / eq was obtained. Moreover, it was confirmed by ¹ H-NMR that 87 mol% of the methoxy group of the partial condensate component of methyltrimethoxysilane was retained.

Example 1 (Production of adhesive composition)
20.0 g of the methoxy group-containing silane-modified epoxy resin (A-1) obtained in Production Example 1, manufactured by Nagase ChemteX Corporation, trade name “Taisan Resin SG-70L” (solid content 12.5% MEK varnish , Glass transition point -17 ° C., acid value 5 mg KOH / g, number average molecular weight 200,000) (component B) 64.0 g, aromatic amine (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “Gascamin 240”, active hydrogen Equivalent 103 g / eq) (Component C) 1.10 g and methyl ethyl ketone 10.0 g were added and uniformly dissolved to prepare an adhesive composition. The blending ratio of the component (B) was 80% by weight with respect to the cured residue of the component (A) in solid content. The functional group having active hydrogen in the component (C) is 1 equivalent relative to 1 equivalent of the epoxy group present in the adhesive composition. The weight in terms of silica in the cured adhesive is 18% by weight.

Example 2 (Production of adhesive composition)
11.5 g of the methoxy group-containing silane-modified epoxy resin (A-1) obtained in Production Example 1, 1.0 g of the methoxy group-containing silane-modified epoxy resin (A-2) obtained in Production Example 2, and Teisan Resin SG- 70 L (component B) 68.0 g, gascamine 240 0.1 g (component C), JER1001 2.3 g, and methyl ethyl ketone 10.0 g were uniformly dissolved to prepare an adhesive composition. The blending ratio of the component (B) is 100% by weight with respect to the curing residue of the component (A). The functional group having active hydrogen in the component (C) is 0.1 equivalent with respect to 1 equivalent of the epoxy group present in the adhesive composition. The weight in terms of silica in the cured adhesive is 12.8% by weight.

Example 3 (Production of adhesive composition)
Except having changed the usage-amount of Taisan resin SG-70L into 80.0g, the same operation was performed by the same preparation amount as Example 1, and the adhesive composition was prepared. The blending ratio of the component (B) is 100% by weight with respect to the curing residue of the component (A), and the weight in terms of silica in the cured adhesive is 16.6% by weight.

Example 4 (Production of adhesive composition)
An adhesive composition was prepared by performing the same operation as in Example 1 except that the amount of Taisan resin SG-70L was changed to 81.5 g. The blending ratio of the component (B) is 120% by weight with respect to the cured residue of the component (A), and the weight in terms of silica in the cured adhesive is 11.7% by weight.

(Comparative Example 1)
10.0 g of JER1001, 1.10 g of gascamine 240, 64.0 g of SG-70L and 20.0 g of methyl ethyl ketone were added and dissolved uniformly to prepare an adhesive composition. The blending ratio of the component (B) is 80% by weight with respect to the curing residue of the component (A). The functional group having active hydrogen in the component (C) is 0.75 equivalent relative to 1 equivalent of the epoxy group present in the adhesive composition.

(Comparative Example 2)
10.19 g of JER1001, 0.23 g of gascamine 240, 81.5 g of SG-70L, and 20.0 g of methyl ethyl ketone were added and dissolved uniformly to prepare an adhesive composition. The blending ratio of the component (B) is 100% by weight with respect to the curing residue of the component (A). The functional group having active hydrogen in the component (C) is 0.1 equivalent with respect to 1 equivalent of the epoxy group present in the adhesive composition.

(Comparative Example 3)
As the acrylic polymer (B), Teisan Resin SG-70L was manufactured by Nagase ChemteX Corporation, trade name "Taisan Resin WS-023" (glass transition point -5 ° C, acid value 20 mgKOH / g, number average molecular weight 110,000). The adhesive composition was prepared in the same manner as in Example 1 except that 8 g of Teisan Resin WS-023 was used and 32 g of methyl ethyl ketone was added. The blending ratio of the component (B) is 80% by weight with respect to the curing residue of the component (A). The weight in terms of silica in the cured adhesive is 18.3% by weight.

(Comparative Example 4)
An adhesive composition was prepared in the same manner as in Example 1, except that the amount of TAISIN RESIN WS-023 used as the acrylic polymer (B) was changed to 6.8 g and 27.2 g of methyl ethyl ketone was added. did. The blending ratio of the component (B) is 80% by weight with respect to the curing residue of the component (A). The weight in terms of silica in the cured adhesive is 14.2% by weight.

(Comparative Example 5)
As acrylic polymer (B), Teisan Resin SG-70L manufactured by Nagase ChemteX Corporation, trade name “Taisan Resin SG-P3” (solid content 15% MEK varnish, glass transition point 15 ° C., acid value 0, number The adhesive composition was prepared in the same manner as in Example 1, except that the average molecular weight was 250,000) and 53.3 g of Teisan resin SG-P3 was added. The blending ratio of the component (B) is 80% by weight with respect to the curing residue of the component (A). The weight in terms of silica in the cured adhesive is 18.3% by weight.

(Comparative Example 6)
An adhesive composition was prepared by performing the same operation as in Example 1 except that the amount of Teisan resin SG-P3 used as the acrylic polymer (B) was changed to 45.3 g. The blending ratio of the component (B) is 80% by weight with respect to the curing residue of the component (A). The weight in terms of silica in the cured adhesive is 14.2% by weight.

<Manufacture of bonded samples: Use of adhesive compositions of Examples 1 and 3 and Comparative Examples 1, 3 and 5>
The adhesive compositions obtained in Examples 1 and 3 and Comparative Examples 1, 3 and 5 were dried on a 50 μm polyethylene naphthalate (PEN) film (trade name “Teonex Q83” manufactured by Teijin DuPont Films) with a roll coater. After coating and drying so that the subsequent thickness becomes 15 μm, the adhesive surface and the treated surface of 18 μm copper foil (product name “F2-WS” manufactured by Furukawa Circuit Foil Co., Ltd.) are superposed on each other at 120 ° C. After pressure bonding with a laminate roll, treatment was performed in an oven at 100 ° C. for 3 hours, 130 ° C., 3 hours, 160 ° C. for 3 hours, the adhesive was cured, and a bonded sample (PEN / adhesive layer / copper foil) was obtained. The laminated sample obtained using the adhesive composition of Example 1 is designated as H-1, and the adhesive sheet samples obtained using the adhesive compositions of Example 3, Comparative Examples 1, 3 and 5 are designated H. -3, G-1, G-3, and G-5. Table 1 shows the results of measuring the peel strength, solder heat resistance, moisture resistance, and volume resistance of the obtained sample.

Peel strength: The peel strength between the copper foil and the film was measured based on JIS C-6482.
Solder heat resistance: After the test piece was heated and dried at 100 ° C. for 60 minutes, it was floated in a solder bath at 260 ° C. for 30 seconds to examine the presence or absence of swelling.
Moisture resistance (humidity solder heat resistance): After placing the test piece in an environment of 80 ° C. and humidity of 85% for 12 hours, a solder heat resistance test was performed.
Volume resistance: Measurement was carried out based on JIS C-6481.

From the above results, it is clear that the adhesive compositions of Examples 1 and 3 are excellent in peel strength and solder heat resistance.

<Production of Adhesive Sheet Sample: Use of Adhesive Compositions of Examples 2, 4 and Comparative Examples 2, 4 and 6>
The adhesive compositions of Examples 2 and 4 and Comparative Examples 2, 4 and 6 were dried on a 50 μm polyethylene naphthalate (PEN) film (trade name “Teonex Q83” manufactured by Teijin DuPont Films) with a roll coater. The adhesive sheet sample (PEN / adhesive layer) was obtained by applying and drying to a thickness of 25 μm. The adhesive sheet sample obtained using the adhesive composition of Example 2 was designated as H-2, and the adhesive sheet samples obtained using the adhesive compositions of Example 4, Comparative Examples 2, 4 and 6 were respectively used. It was set as H-4, G-2, G-4, and G-6.

Table 2 shows various physical properties of the sheet sample obtained in the previous section. The measuring method is as follows.
Transparency: Measured based on haze value (cloudiness value), JIS K 7105. The adhesive sheet sample was measured with the adhesive layer in the B stage.
Transparency of adhesive layer: A value obtained by subtracting the haze value of the PEN film from the haze value of the laminate.
Peel strength: Adhesive sheet sample for measuring adhesive strength is to superimpose the adhesive layer side of the adhesive sheet sample on the mirror surface side of the copper foil, and heat-press bond at 140 ° C, 2.0 MPa for 2 hours with a hot press. A test piece (PEN / adhesive layer / copper foil) was prepared.
Solder heat resistance: After the test piece used in the peel strength test was heated and dried at 100 ° C. for 60 minutes, it was floated in a solder bath at 260 ° C. for 30 seconds to examine the presence or absence of swelling.

From the above results, the adhesive compositions of Examples 2 and 4 are excellent in transparency, peel strength, and solder heat resistance, and are useful as adhesive compositions used for coverlay films.

<Manufacture of laminated film samples>
The copper foils of the bonded samples obtained in Examples 1 and 3 and Comparative Examples 1, 3 and 5 were removed by whole surface etching with an aqueous iron chloride solution, and in Examples 2, 4 and Comparative Examples 2, 4 and 6, respectively. The obtained adhesive sheet sample was laminated on the adhesive layer side, and heated and pressed at 140 ° C., 2.0 MPa for 2 hours, and laminated film sample (PEN / adhesive sheet sample adhesive layer / bonded sample adhesive layer / PEN). The transparency of each obtained film sample was measured based on the above-mentioned JIS K 7105. The results are shown in Table 3.

From the above results, a flexible printed circuit board having excellent transparency was produced by combining the copper-clad laminate obtained from the adhesive compositions of Examples 1 and 3 and the coverlay film obtained from Examples 2 and 4. Is possible.

<Hardened film sample: Use of adhesive compositions of Examples 1 and 3 and Comparative Examples 1, 3 and 5>
The adhesive compositions obtained in Examples 1 and 3 and Comparative Examples 1, 3 and 5 were cast on an aluminum cup and cured at 50 ° C. for 12 hours and at 150 ° C. for 3 hours to obtain a cured film having a thickness of 500 μm. Obtained.
Transparency of cured film: Measured based on haze value (cloudiness value), JIS K 7105.
Water absorption: The cured film was placed in an absolute dry state at 50 ° C. for 24 hours and then immersed in water for 24 hours to determine the water content. The results are shown in Table 4.

From the above results, it is clear that the adhesive compositions of Examples 1 and 3 are excellent in transparency, insulation and moisture resistance.

Claims (6)

  A methoxy group-containing silane-modified epoxy resin (A) obtained by dealcoholizing a bisphenol type epoxy resin (a-1) and a methoxysilane partial condensate (a-2), having a carboxyl group, and having a glass transition point of 20 For laminates characterized by containing an acrylic polymer (B) having an acid value of 2 to 10 (mg KOH / g), a number average molecular weight of 150,000 to 300,000, and a curing agent for epoxy resin (C). Adhesive composition.   The adhesive composition for laminates according to claim 1, wherein the methoxysilane partial condensate (a-2) is a partial condensate of tetramethoxysilane and / or methyltrimethoxysilane.   The adhesive composition for laminates according to claim 1, wherein the blending amount of the acrylic polymer (B) is 90 to 200% with respect to the curing residue of the silane-modified epoxy resin (A).   The adhesive composition for laminates according to any one of claims 1 to 3, wherein the epoxy resin curing agent (C) is at least one selected from the group consisting of aromatic amines and novolak phenol resins.   The adhesive composition for laminates according to any one of claims 1 to 4, which has a haze value of 5% or less when formed into a 15 µm cured film.   A laminate obtained by bonding polyethylene naphthalate or polyethylene terephthalate using the adhesive composition for laminates according to any one of claims 1 to 5, wherein the laminate has a haze value of 20% or less. body.