KR20140068946A - Liquid ink - Google Patents

Abstract

A liquid ink containing a thermosetting resin composition comprising an organic polymer, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition. When the thermosetting resin composition is cured, a cured product (1) having a storage elastic modulus at 25 占 폚 of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa is formed.

Description

Liquid ink {LIQUID INK}

The present invention relates to a liquid ink.

BACKGROUND ART [0002] Conventionally, various printed wiring boards of one side, both sides, or multiple layers are widely used in the field of industrial devices or consumer electronic devices. In the case of an electronic apparatus, only one printed wiring board is rarely used, and for example, a plurality of printed wiring boards divided into functional units are generally used. Normally, a plurality of wiring boards are connected by various connectors.

BACKGROUND OF THE INVENTION [0002] Electronic devices are aimed at thin and light small-sized devices. In recent years, high-density mounting printed wiring boards representing thin and light chips have been assembled in recent cellular phones, video cameras, and notebook PCs. In such an electronic apparatus, it is necessary to compactly mount a plurality of printed wiring boards in a limited space. However, when the boards of these wiring boards are connected by a connector, the volume becomes large, so that connection by the connector is already difficult. For this reason, various flexible rigid wiring boards in which a flexible substrate such as a polyimide film substrate and a rigid substrate are combined have been proposed.

For example, there has been proposed a manufacturing method of a rigid flexible wiring board in which a rigid substrate and a flexible substrate are thermocompression-bonded via an adhesive sheet, and a rigid substrate and a circuit of a flexible substrate are electrically connected by a through hole (for example, See Patent Document 1).

Further, a rigid substrate having no flexibility is laminated on a flexible substrate having flexibility, and a flexible substrate is partially exposed on the rigid substrate to expose the flexible substrate. Thus, A method of manufacturing a substrate has been proposed (see, for example, Patent Document 2).

Furthermore, it has been proposed to increase the thickness of the conductor portion of the printed wiring board to partially impart rigidity (see, for example, Patent Document 3).

Patent Document 1: JP-A-2-39594 Patent Document 2: JP-A-5-90756 Patent Document 3: JP-A-2006-352103

SUMMARY OF THE INVENTION A principal object of the present invention is to provide a liquid ink capable of enhancing the rigidity of an arbitrary portion which does not require bending property while maintaining a good bending property with respect to a flexible substrate such as a flexible printed wiring board.

The present invention relates to a liquid ink containing a thermosetting resin composition comprising an organic polymer, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition. When the thermosetting resin composition is cured, a cured product having a storage elastic modulus at 25 ° C of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa may be formed.

According to the liquid ink according to the present invention, since the cured product of the thermosetting resin composition to which the inorganic filler is applied has the specific storage elastic modulus and the tensile elastic modulus as described above, the flexible substrate such as a flexible printed wiring board, The rigidity of any portion that does not require bending properties can be increased.

The thermosetting resin composition may contain 50% by mass or more of an inorganic filler based on the mass of the total solid content (components other than the solvent in the liquid ink) of the thermosetting resin composition. The organic polymer may include an acrylic resin. Thereby, the thermosetting resin forming the cured product having the specific storage elastic modulus and the tensile elastic modulus is particularly easily constituted.

The acrylic resin may have a glycidyl group. The weight average molecular weight of the acrylic resin may be 400,000 to 1,800,000, 500,000 to 1,500,000, or 800,000 to 1,400,000.

The inorganic filler may contain silica particles. The silica particles may be surface-treated with a silane coupling agent. Thereby, sedimentation of the silica particles is suppressed, and a liquid ink having higher stability can be obtained. From the same viewpoint, the silane coupling agent may have an amino group.

The thermosetting resin may contain an epoxy resin. In this case, the thermosetting resin composition may further contain a phenol resin.

The epoxy resin may contain a biphenyl aralkyl type epoxy resin. The biphenyl aralkyl type epoxy resin exhibits high compatibility with an organic polymer such as an acrylic resin, and therefore, a liquid ink excellent in dispersion stability can be obtained by using the biphenyl aralkyl type epoxy resin.

The liquid ink according to the present invention can be used for applying a liquid ink to a polyimide film base material and curing the applied liquid ink to form a cured film for enhancing the rigidity of the polyimide film base material.

Further, the liquid ink according to the present invention can be used for applying a liquid ink to a flexible printed wiring board, curing the applied liquid ink, and forming a cured film for enhancing the rigidity of the flexible printed wiring board.

According to the present invention, there is provided a liquid ink capable of enhancing the rigidity of an arbitrary portion which does not require bending property while maintaining good bending property, with respect to a flexible substrate such as a flexible printed wiring board.

The cured film formed by the liquid ink according to the present invention exhibits good adhesion to the polyimide film. Therefore, by applying a liquid ink to a portion of the flexible printed circuit board having the polyimide film substrate as a substrate, which does not require bending property, and forming a cured film, the rigidity of the flexible wiring board at the portion where the cured film is formed is avoided It is possible to make it to have a rigid property. That is, a rigid-flexible printed wiring board having a rigid portion and a flexible portion can be manufactured by a simple process. Such a rigid-flexible printed wiring board can contribute to weight reduction of various electronic apparatuses.

Moreover, since the cured film formed by the liquid ink according to the present invention has a high underflow property, a high level of underflow property required when using lead-free solder is easily achieved.

1 is a cross-sectional view showing an embodiment in a state in which a cured film is in contact with a substrate.
2 is a stress-displacement curve and a tangent line of the cured product of the liquid ink obtained in Example 11. Fig.

Hereinafter, a preferred embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

1 is a cross-sectional view showing an embodiment in a state in which a cured film 1 is in contact with a substrate 10. Fig. The substrate 10 is a flexible substrate having flexibility such as a polyimide film. The rigidity of the substrate 10 is higher in the portion in contact with the cured film 1 as compared with the case where the cured film 1 is not formed. In other words, in the portion in contact with the cured film 1, the self-supporting property of the base material 10 is enhanced. When the base material 10 is a flexible printed wiring board, the base material 10 in contact with the cured film 1 can function, for example, as a rigid part of a rigid-flexible wiring board.

The liquid ink according to the present embodiment can be used for forming the cured film 1. For example, the liquid ink is applied to the substrate 10, and the applied liquid ink is cured, whereby the cured film 1 is formed. The thickness of the cured film 1 is 50 to 300 mu m, 80 to 200 mu m, or 100 to 150 mu m.

The liquid ink according to this embodiment contains a thermosetting resin composition containing an organic polymer as a polymer material, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition.

(For example, the cured film 1) having a storage elastic modulus at 25 ° C of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa when the thermosetting resin composition in the liquid ink is cured by heating, Is formed.

The storage elastic modulus of the cured product at 25 캜 is measured by measuring the dynamic viscoelasticity of the cured product on the film. More specifically, the storage elastic modulus of the cured product at 25 캜 was determined by measuring the dynamic viscoelasticity of the film-shaped cured product having a width of 5 mm and a length of 30 mm in a tensile mode, a distance between chucks of 20 mm, a cycle of 10 Hz, And the storage elastic modulus at 25 캜 is read from a viscoelastic curve showing the relationship between the storage elastic modulus and the temperature. The cured product as a measurement sample is formed, for example, by drying a coating film of a liquid ink having a thickness of 125 mu m by heating at 110 DEG C for 10 minutes and then curing by heating at 185 DEG C for 30 minutes.

The tensile modulus of elasticity is calculated from the maximum value of the slope of the tangent line of the stress-displacement curve (elastic deformation portion) obtained when a short-cured cured product is prepared as a measurement sample and tensile stress is applied thereto at a tensile speed of 50 mm / Is the initial modulus of elasticity obtained. The tensile test is usually conducted in an atmosphere of about 23 캜.

The tensile modulus of the cured product of the thermosetting resin composition according to this embodiment varies mainly depending on the content ratio of the inorganic filler having a high elastic modulus. In the thermosetting resin composition comprising an organic polymer, a thermosetting resin and an inorganic filler, when the content of the inorganic filler is 50 mass% or more based on the mass of the thermosetting resin composition, the thermosetting resin composition preferably has a tensile modulus of 0.5 GPa to 3.0 GPa Cargo is likely to form. Since the tensile modulus of the cured product of the liquid ink is in the range of 0.5 GPa to 3.0 GPa, cracks are unlikely to occur in the cured film when the substrate is bent together with the cured film. That is, the cured film 1 can be formed while maintaining high flexibility of the substrate 10. From the same viewpoint, the tensile elastic modulus of the cured product of the liquid ink material may be 0.7 GPa to 2.0 GPa.

On the other hand, the storage elastic modulus of the cured product of the thermosetting resin composition according to the present embodiment, unlike the tensile elastic modulus, is not significantly affected by the inorganic filler, and is maintained at a relatively low value mainly reflecting the low elastic modulus of the resin component. Specifically, the storage modulus at 25 占 폚 of the cured product may be 500 MPa or less, or 120 MPa or less. Since the storage elastic modulus of the cured product is low, particularly excellent bending property and bottom flowability are achieved. The lower limit of the storage elastic modulus is usually about 10 MPa and may be 25 MPa.

A preferred embodiment of a thermosetting resin composition for forming a cured film having the above characteristics will be described in detail below.

As described above, the thermosetting resin composition according to the present embodiment may contain an inorganic filler in an amount of 50 mass% or more based on the mass of the total solid content (component other than the solvent in the liquid ink) of the thermosetting resin composition. The content of the inorganic filler may be 70 mass% or more. The content of the inorganic filler may be 90 mass% or less, or 80 mass% or less from the viewpoint of the tensile elastic modulus.

The inorganic filler may be composed of one kind of particles or a combination of two or more kinds of particles. The average particle diameter of the inorganic filler may be 1 to 100 탆, 1 to 50 탆, 1 to 20 탆, or 1.5 to 10 탆. The inorganic filler may be a mixture of plural kinds of fillers having different average particle diameters. Thereby, the space filling rate by the inorganic filler can be increased.

The inorganic filler may be silica particles. The silica particles may be, for example, spherical silica obtained by a sol-gel method, crushed silica finely pulverized, dry silica, or wet silica.

Examples of commercially available products of spherical silica include MSR-2212, MSR-SC3, MSR-SC4, MSR-3512 and MSR-FC208 (trade names, manufactured by Rumorihi- SO3, SO2, SO2, SO2, SO2, SO2, SO2, SO2, SO2, ). CMC-1, VX-S2 and VX-SR (trade names, manufactured by Rumoriti Kagaku Co., Ltd.) were used as commercially available products of the crushed silica, , F05, F05-30, F05-12 (trade names, manufactured by Fukushima Yoshi Kogyo Co., Ltd.), and the like. (Manufactured by TOKUYAMA CORPORATION) can also be used as the non-woven fabric.

The silica particles may be surface-treated with a silane coupling agent. Thereby, sedimentation of the silica particles is suppressed, and a liquid ink having higher dispersion stability can be obtained.

Examples of the silane coupling agent as a surface treatment agent used for surface treatment of silica particles include vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3- Methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3- N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane diethoxysilane, n-2- (aminoethyl) Aminopropyltrimethoxysilane, n-2- (aminoethyl) -3-aminopropyltriethoxysilane Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl- 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, (Triethoxysilylpropyl) tetrasulfide, 3-isocyanate propyltriethoxysilane, polycondensation product of dimethylsilane, polycondensation product of diphenylsilane, dimethylsilane and diphenylsilane ≪ / RTI > Among them, a silane coupling agent having an amino group can be selected.

The organic polymer constituting the thermosetting resin composition may be an acrylic resin or a polyamideimide resin from the viewpoints of adhesiveness with the polyimide film substrate and heat resistance.

The polyamideimide resin may have a siloxane group and / or an aliphatic group in addition to an amide group and an imide group. The weight average molecular weight of the polyamide-imide resin may be 10000 to 1500000, 30000 to 100000, or 50,000 to 80000. In the present specification, the weight average molecular weight is a standard polystyrene conversion value determined by GPC measurement.

The acrylic resin is generally a copolymer composed of a polymerizable monomer containing two or more kinds of acrylic monomers. The acrylic resin can be produced at a low cost by combining a wide variety of commercially available acrylic monomers with a wide range of properties. In addition, since acrylic resins have good solubility in ketone solvents having a low boiling point, they are excellent in that printed liquid ink can be easily dried.

The acrylic monomer constituting the acrylic resin is not particularly limited, and examples thereof include acrylonitrile, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, Butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, phenyl acrylate, benzyl acrylate, naphthyl acrylate, cyclohexyl acrylate isobornyl acrylate, norbornyl methyl acrylate, tricyclo [5.2.1.O ^2,6] deca-8-yl (dicyclopentanyl acrylate) acrylate, tricyclo [5.2.1.O ^2,6] deca 4-methyl acrylate, adamantyl acrylate, isobornyl acrylate, norbornyl acrylate, tricyclohexyl acrylate [5.2.1.O ^2,6 ] deca-8-yl acrylate, tricyclohexyl acrylate [5.2.1.O ^2,6] deca-4-methyl, and the acid-adamantyl (Meth) acrylate, n-propyl methacrylate, n-butyl methacrylate (butyl methacrylate), i-butyl methacrylate , T-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, octyldodecyl methacrylate, octadecyl methacrylate, Ethyl, cyclopentyl methacrylate, cyclohexyl methacrylate, methylcyclohexyl methacrylate, tricyclohexyl methacrylate, norbornyl methacrylate, methacrylic acid Norbornylmethyl, isobornyl methacrylate, boronyl methacrylate, menthyl methacrylate, adamantyl methacrylate, methacrylic acid tricyclo [5.2.1.o ^2,6 ] deca-8-yl claw fentanyl methacrylate), and methacrylate, tricyclo [5.2.1.O ^2,6] deca-4, such as methyl methacrylate Is one or two or more kinds of monomers selected from esters.

From the viewpoint of the heat resistance and adhesiveness of the cured film formed from the liquid ink, the acrylic monomer constituting the acrylic resin is at least one functional group selected from the group consisting of carboxyl group, hydroxyl group, acid anhydride group, amino group, amide group and epoxy group And a functional group-containing monomer having at least one (meth) acrylic group. The functional group-containing monomer includes, for example, a monomer having a carboxyl group such as acrylic acid, methacrylic acid and itaconic acid, a monomer having a carboxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, Containing monomers such as methyl acrylate, 2-hydroxypropyl acrylate, N-methylol methacrylamide and hydroxyl group-containing monomers such as (o-, m-, p-) hydroxystyrene, monomers containing acid anhydride groups such as maleic anhydride, Ethylaminoethyl and diethylaminoethyl methacrylate, and monomers containing an amino group such as glycidyl acrylate, glycidyl methacrylate (glycidyl methacrylate), glycidyl α-ethyl acrylate, α-n- Epoxypropyl acrylate, glycidyl methacrylate, glycidyl acrylate, 3,4-epoxybutyl acrylate, 3,4-epoxybutyl methacrylate, 4,5,5- 7-epoxyheptyl, 3-methyl-4-epoxybutyl acrylate, 3-methyl- Methyl-4,5-epoxypentyl methacrylate, 4-methyl-4,5-epoxypentyl acrylate, 5-methyl-5,6-epoxyhexyl acrylate, Methylglycidyl methacrylate,? -Methyl glycidyl methacrylate,? -Methyl glycidyl acrylate, 3-methyl-3,4-epoxybutyl acrylate, -Epoxybutyl acrylate, 4-methyl-4,5-epoxypentyl acrylate, 4-methyl-4,5-epoxypentyl methacrylate, 5-methyl acrylate, 6-epoxyhexyl acrylate, and methacrylic acid- -Methyl-5,6-epoxyhexyl, and other epoxy group-containing monomers. These may be used alone or in combination of two or more.

The acrylic resin may further contain other monomers copolymerized with the acrylic monomer. Other monomers include, for example, 4-vinylpyridine, 2-vinylpyridine,? -Methylstyrene,? -Ethylstyrene,? -Fluorostyrene,? -Chlorostyrene,? -Bromostyrene, fluorostyrene, Aromatic vinyl compounds such as styrene, bromostyrene, methylstyrene, methoxystyrene and styrene and aromatic vinyl compounds such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, Substituted maleimides such as N-methylmaleimide, N-butylmaleimide, Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide and N-phenylmaleimide . ≪ / RTI >

The acrylic resin may have a glycidyl group particularly when the thermosetting resin is an epoxy resin. Since the acrylic resin has a glycidyl group, the heat resistance of the cured film can be further increased. Therefore, the acrylic resin may contain glycidyl methacrylate or glycidyl acrylate, which is a functional group-containing monomer, as a monomer unit. The content of glycidyl methacrylate may be from 0.5 to 10 mass%, from 1 to 8 mass%, or from 2 to 5 mass% based on the amount of all the polymerizable monomers constituting the acrylic resin.

The acrylic resin may contain an alkyl acrylate as a monomer from the viewpoint of adhesion with a flexible wiring board when it is a cured film. The alkyl group of the alkyl acrylate may have 1 to 12 carbon atoms or 2 to 10 carbon atoms. The content of the alkyl acrylate may be from 50 to 99% by mass, from 60 to 98% by mass, or from 70 to 96% by mass, based on the amount of all the polymerizable monomers constituting the acrylic resin. The alkyl acrylates are selected, for example, from ethyl acrylate and butyl acrylate.

The acrylic resin may contain acrylonitrile or methacrylonitrile as a monomer from the viewpoint of toughness and adhesiveness. The content of acrylonitrile or methacrylonitrile may be from 0.5 to 10 mass%, from 1 to 8 mass%, or from 2 to 5 mass% based on the amount of all the polymerizable monomers constituting the acrylic resin.

The acrylic resin may be, for example, a copolymer of glycidyl methacrylate and alkyl (meth) acrylate, a copolymer of glycidyl methacrylate, alkyl (meth) acrylate and (meth) acrylonitrile, (Meth) acrylate, and dicyclopentanyl (meth) acrylate.

The weight average molecular weight of the acrylic resin may be 400,000 to 1,800,000, 500,000 to 1,500,000, or 800,000 to 1,400,000. If the weight average molecular weight is less than 400,000, the viscosity of the liquid ink is low, so that the dispersion stability of the inorganic filler may be deteriorated or the liquid ink may not be able to exhibit thixotropy. In addition, when the weight average molecular weight of the acrylic resin is low, the cured film tends to be broken, and the curvature of the cured film tends to be lowered. When the weight average molecular weight of the acrylic resin exceeds 180,000, solubility in a solvent is remarkably lowered, and it tends to be difficult to increase the concentration of solid content in the liquid ink. When the concentration of the solid content of the liquid ink is low, it is necessary to control the film thickness of the applied liquid ink and reduce the film due to drying shrinkage.

The glass transition temperature (Tg) of the acrylic resin may be -50 to 100 占 폚, -45 to 20 占 폚, or -40 占 to 5 占 폚. When the glass transition temperature of the acrylic resin is within these numerical values, the storage elastic modulus and the tensile elastic modulus of the cured film can be easily controlled while the sticking of the cured film is suppressed. The Tg of the acrylic resin can be measured by DSC (differential scanning calorimetry), but the Tg of the acrylic resin composed of n kinds of monomers can be calculated by the following calculation formula (FOX formula).

Tg (℃) = {1 / (W 1 / Tg 1 + W 2 / Tg 2 + ... + W i / Tg i + ... + W n / Tg n)} - 273

In the FOX formula, Tg _i (K) represents the glass transition temperature of the homopolymer of each monomer, W _i represents the mass fraction of each monomer, W ₁ + W ₂ + + W _i + ... W _n = 1.

For example, the acrylic resin obtained by copolymerizing 5% by mass of glycidyl methacrylate, 5% by mass of acrylonitrile, 85% by mass of ethyl acrylate and 5% by mass of butyl acrylate has a glass transition temperature (Tg) is calculated as follows.

Tg = {1 / (0.05 / 319 + 0.05 / 498 + 0.85 / 251 + 0.05 / 219)} - 273 = -14.7 DEG C

The thermosetting resin constituting the thermosetting resin composition is a compound having a curable functional group (for example, an epoxy group). The thermosetting resin may be a thermosetting resin selected from, for example, an epoxy resin, a polyimide resin, a polyamideimide resin, a triazine resin, a phenol resin, a melamine resin, a polyester resin, a cyanate ester resin, Two or more.

The thermosetting resin may contain a high molecular weight component for the purpose of improving the flexibility and heat resistance of the cured film. However, the molecular weight of the thermosetting resin is usually 3,000 or less.

Examples of the epoxy resin include polyglycols obtained by reacting polyhydric alcohols such as bisphenol A, novolak type phenol resins, and orthocresol novolak type phenol resins, or polyhydric alcohols such as 1,4-butanediol with epichlorohydrin Glycidyl derivatives of polyglycidyl esters obtained by reacting a polybasic acid such as cidyl ether, phthalic acid and hexahydrophthalic acid with epichlorohydrin, N-glycidyl derivatives of compounds having an amino group, amide group or heterocyclic nitrogen group, Type epoxy resins. Among them, polyglycidyl ethers selected from biphenyl aralkyl type epoxy resins and naphthalene type tetrafunctional epoxy resins, and N-glycidyl derivatives of compounds having an amide group or heterocyclic nitrogen group, , Acrylic resin).

Examples of the phenol resin include phenol resins such as phenol resins, bisphenol A resins, cresol novolak resins and aminotriazine novolak resins. From the viewpoint of compatibility with an acrylic resin, one or both of cresol novolak type and aminotriazine novolak type phenol resins can be selected. The amine triazine novolac-type phenol resin has a structural unit represented by the following structural formula (I). When combined with an epoxy resin, the phenol resin sometimes functions as a curing agent for the epoxy resin.

[In the formula (I), R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 30.]

The thermosetting resin composition may contain a curing agent usually used for curing the thermosetting resin. For example, when the thermosetting resin is an epoxy resin, the curing agent may be selected from dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, phthalic anhydride, pyromellitic anhydride, and phenol novolak and cresol novolac Polyfunctional phenols.

Often, an accelerator can be used for the purpose of promoting the reaction between the thermosetting resin and the curing agent. The kind and blending amount of the promoter are not particularly limited. For example, an imidazole-based compound, an organophosphorous compound, a tertiary amine and a quaternary ammonium salt are used, and two or more kinds of them may be used in combination.

Based on the total mass of the organic polymer (acrylic resin, etc.), the thermosetting resin (epoxy resin, etc.) and the curing agent (phenol resin, etc.) (which may correspond to the total mass of components other than the inorganic filler of the thermosetting resin composition) The content of the organic polymer may be 40 to 90 mass%, 50 to 85 mass%, or 60 to 80 mass%. The total amount of the glycidyl group of the acrylic resin and the epoxy group of the epoxy resin and the amount of the hydroxyl group of the phenol resin may be substantially equivalent. The ratio of the thermosetting resin to the curing agent is suitably set within a range usually employed in consideration of the reactivity and the like.

As the solvent constituting the liquid ink, for example, a ketone solvent such as methyl ethyl ketone, cyclohexanone and the like can be used. From the viewpoint of printability, cyclohexanone can be selected. The concentration of the thermosetting resin composition (component other than the solvent) in the liquid ink may be 40 to 70 mass% based on the mass of the liquid ink.

The liquid ink can be prepared by mixing each component constituting the thermosetting resin composition with a solvent and stirring them as necessary. The inorganic filler may be dispersed in an organic solvent containing a surface treatment agent in advance to be slurried. The solid content concentration (inorganic filler concentration) of the slurry including the inorganic filler and the solvent is not particularly limited, but is preferably 50 to 90 mass%, 60 to 80 mass%, or 65 to 75 mass% . A mixture of an organic polymer, a thermosetting resin and a curing agent may be prepared in advance. This mixture and a slurry of an inorganic filler are mixed to obtain a liquid ink.

The liquid ink according to this embodiment is applied to a predetermined portion of the substrate to form a cured film. The coating method may be, for example, continuous coating such as bar coating, comma coating and roll coating, or a printing method such as screen printing and metal mask printing.

The applied liquid ink (coating film) is dried and cured as required. The drying temperature may be 50 to 150 캜, 80 to 130 캜, or 100 to 120 캜. The coating film is cured by treatment at a higher temperature. The curing temperature may be 150 to 250 캜, 160 to 200 캜, or 180 to 190 캜.

Example

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

Example 1

7 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, trade name, manufactured by Shin-Etsu Silicones Co., Ltd.) as a surface treatment agent was dissolved in 300 g of methyl ethyl ketone. To this, F05-12 Ltd.) was added with stirring, and then stirred at room temperature for an additional 1 hour. The coagulated material of the crushed silica was separated by filtration using a 200 mesh nylon cloth to obtain a slurry-like filtrate (silica slurry). (MEK) solution (concentration 20 mass%) of a copolymer of glycidyl methacrylate, ethyl acrylate and butyl acrylate (weight average molecular weight: 1.3 million, epoxy equivalent: 7800, Tg-45 ° C) And 34.2 g of a MEK solution (concentration 50% by mass) of a biphenyl aralkyl type epoxy resin (NC-3000H, trade name, manufactured by Nippon Kayaku Co., Ltd.) 25.8 g of an MEK solution (concentration of 50% by mass) having a number average molecular weight of 5,000 and a 1-cyanoethyl-2-phenylimidazole (2PZ-CN, trade name of Shikoku Kasei K.K.) Solution. To this resin solution, 430 g of a silica slurry was added and stirred for 1 hour to obtain a liquid ink.

Examples 2 to 11, Reference Examples 1 to 4 and Comparative Examples 5 to 8

Liquid inks were prepared in the same manner as in Example 1, except that the respective materials shown in Tables 1 and 2 were used at the blending ratios shown in Tables. The compounding ratio of the organic polymer, the thermosetting resin and the curing agent is based on the mass of the thermosetting resin composition other than the inorganic filler, and the compounding ratio of the inorganic filler is determined based on the mass of the total solids (component other than the solvent in the liquid ink) .

Example 12

7 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, trade name, manufactured by Shin-Etsu Silicones Co., Ltd.) as a surface treatment agent was dissolved in 300 g of cyclohexanone, to which was added SO-25R Ltd.) was added with stirring, and then stirred at room temperature for an additional 1 hour. The coagulated material of the spherical silica was separated by filtration using 200 mesh nylon bubbles to obtain a slurry filtrate (silica slurry). 350 g of a cyclohexanone solution (concentration of 20% by mass) of a copolymer of glycidyl methacrylate, acrylonitrile, ethyl acrylate and butyl acrylate as an acrylic resin (weight average molecular weight: 450,000, Tg- And 34.2 g of a cyclohexanone solution (concentration 50% by mass) of a biphenyl aralkyl type epoxy resin (NC-3000H, trade name, manufactured by Nippon Kayaku Co., (Concentration: 50% by mass) and 0.5 g of 1-cyanoethyl-2-phenylimidazole (2PZ-CN, trade name, manufactured by Shikoku Kasei K.K.) were mixed , And stirred to obtain a resin solution. To this resin solution, 430 g of the silica slurry (concentration of inorganic filler: 70 mass%) was added and stirred for 1 hour to obtain a liquid ink.

Details of each material shown in Tables 1 and 2 are as follows.

1. Acrylic resin

GMA / EA / BA: Copolymer of glycidyl methacrylate, ethyl acrylate and butyl acrylate (compounding ratio of monomer: GMA / EA / BA = 2/26/72 (mass ratio), Tg: )

A copolymer of glycidyl methacrylate, acrylonitrile, ethyl acrylate and butyl acrylate (mixing ratio of monomer: GMA / AN / EA / BA = 5/5/85 / 5 (mass ratio), Tg: -14.7 占 폚)

A copolymer of glycidyl methacrylate, ethyl acrylate, butyl acrylate and dicyclopentanyl acrylate (mixing ratio of monomers: GMA / EA / BA / FA513AS = 5/28 / 38.5 / 28.5 (mass ratio), Tg: -6.7 ° C)

2. Epoxy resin

NC-3000H: biphenyl aralkyl type epoxy resin (trade name, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 290)

EXA4710: Naphthalene type tetrafunctional epoxy resin (trade name, manufactured by Dainippon Ink and having an epoxy equivalent of 170)

N770: phenol novolak type epoxy resin (manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent 188)

3. Phenolic resin (hardener)

LA-3018: Aminotriazine novolak type phenol resin (trade name, manufactured by Dainippon Ink and Chemicals, Inc., hydroxyl equivalent: 151, nitrogen content: 18%)

KA-1165: Cresol novolak type phenolic resin (trade name, manufactured by Dainippon Ink and Chemicals, Inc., hydroxyl equivalent of 119)

LA-1356: Aminotriazine novolak type phenolic resin (trade name, manufactured by Dainippon Ink and Chemicals, Inc., hydroxyl equivalent 146, nitrogen content 19%)

4. Silica particles

F05-12: Fractured silica, product name of Fukushima Yoshinobu Co., Ltd.

ㆍ F05-30: Fractured silica, product name of Fukushima Yoshinobu Co., Ltd.

SO-C6 / SO-E3: spherical silica, trade name of product manufactured by Admatech Kabushiki Kaisha

ㆍ SO-25R: spherical silica, product name of Admatech Co., Ltd.

5. Surface treatment agent (silane coupling agent)

KBM573: N-phenyl-3-aminopropyltrimethoxysilane, trade name of Shin-Etsu Silicone Co., Ltd.

KBM602: N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, trade name of Shin-Etsu Silicone Co., Ltd.

KBM903: 3-aminopropyltrimethoxysilane, trade name of Shin-Etsu Silicone Co., Ltd.

KBM5103: 3-acryloxypropyltrimethoxysilane, trade name of Shin-Etsu Silicone Co., Ltd.

ㆍ DMDS / TEMOS: polysiloxane oligomer formed by dimethyldimethoxysilane (DMDS) and tetramethoxysilane (TEMOS)

(evaluation)

1. Adhesion to polyimide film

A liquid imide was applied to a polyimide film (UVRex 50S) using a bar coater so as to have a thickness of 125 mu m after drying. The applied liquid ink was dried by heating at 110 占 폚 for 10 minutes and then cured by heating at 185 占 폚 for 30 minutes to form a cured film in close contact with the polyimide film. The cured film was divided into a checkerboard shape by a cutter knife with ten shears spaced at 2 mm intervals and 10 shears spaced at 2 mm intervals at right angles to these. The adhesive tape was stuck thereon, and the adhesive was peeled off, and the adhesiveness was evaluated based on the number of checkered eyes remaining on the polyimide film. When the number of checkered eyes remained on the polyimide film was large, it was judged that the adhesion to polyimide was good.

2. Storage elasticity of cured product

A liquid-phase ink having a thickness of 125 占 퐉 after drying was applied to a release-treated PET (polyethylene terephthalate) film using a bar coater. The applied liquid ink was dried by heating at 110 占 폚 for 10 minutes and then cured by heating at 185 占 폚 for 30 minutes to form a cured film (cured product). A specimen having a width of 5 mm and a length of 30 mm was punched out from the cured product peeled off from the release-treated PET film. The sample was subjected to viscoelasticity measurement at a chuck distance of 20 mm, a cycle of 10 Hz, and a temperature raising rate of 5 deg. C / minute using a dynamic viscoelasticity measuring apparatus (REOGEL4000 manufactured by Rheology). From the obtained viscoelastic curve, the storage elastic modulus and Tg at 25 캜 were obtained.

3. Mechanical Properties of Cured Products

A liquid-phase ink having a thickness of 125 占 퐉 after drying was applied to a release-treated PET (polyethylene terephthalate) film using a bar coater. The applied liquid ink was dried by heating at 110 占 폚 for 10 minutes and then cured by heating at 185 占 폚 for 30 minutes to form a cured film (cured product). A specimen having a width of 10 mm and a length of 100 mm was punched out from the cured product peeled off from the release-treated PET film. This sample was subjected to a tensile test at a tensile speed of 50 mm / min using an EZ tester to obtain a stress-displacement curve. From the maximum value of the slope of the tangent line of the stress-displacement curve at the beginning, the tensile elastic modulus was determined according to the following formula. The stress-displacement curve of the cured product of the liquid ink obtained in Example 11 is shown in Fig. The tensile modulus was calculated from the slope of the tangent line T having the maximum slope in the tangent line of the stress-displacement curve in Fig.

Tensile modulus (Pa) = maximum value of tangent slope of stress-displacement curve (N / m) x

[Displacement (m) / cross-sectional area of cured product (m ² )]

4. Self-supporting property

A liquid ink in an amount such that the thickness after drying was 125 占 퐉 was applied to a polyimide film (UFIREX 50S) using a bar coater. The applied liquid ink was dried by heating at 110 占 폚 for 10 minutes and then cured by heating at 185 占 폚 for 30 minutes to form a cured film (cured product). The cured film was punched with a polyimide film to a size of 10 mm in width and 100 mm in length to obtain a sample. The obtained samples were placed on two pedestals provided at intervals of 80 mm so as to cover their pedestals, and the amount of sinking of the central portion of the sample at that time was measured. When the settling amount was 10 mm or less, it was judged that there was self-supporting property.

5. Bendability

A pin gauge of 0.3 mm was applied to a sample composed of a polyimide film and a cured film laminated thereon, and the sample was bent to about 180 degrees while winding the sample thereon, and the presence or absence of cracks at that time was observed. A polyimide film was placed on the outer side or the inner side of the pin gauge to perform the same evaluation. When the occurrence of cracks was not confirmed, it was judged that bending property was good.

6. Down flow

A sample composed of a polyimide film and a cured film laminated thereon was sandwiched between two wire nettings, and a conveyor type reflow test was conducted. That is, the sample was treated three times with a heating profile in which the maximum temperature of the surface of the sample was 260 DEG C at a speed of 1.2 m / min and the temperature was maintained for 10 seconds. After the treatment, the presence or absence of swelling and peeling between the polyimide film and the cured film was confirmed by visual observation of the appearance. When the expansion and peeling were not confirmed, it was judged that the flowability was good.

(result)

The liquid inks of Examples had excellent dispersion stability, and no aggregation of silica was observed even after being left for 2 weeks. Self-supporting property could be imparted to the polyimide film by the cured film formed by these liquid inks. Also, the cured film had good adhesion to the polyimide, and there was no problem with the down flow. In the liquid ink of Reference Example 1, there was a problem in stability because silica was aggregated. In the liquid inks of Reference Examples 2 and 3, since the resin was separated, there was a problem in stability. The cured film formed by the liquid ink of Comparative Example 5 could not impart self-supporting property to the polyimide film. The cured film formed by the liquid ink of Comparative Example 6 could not be bent together with the polyimide film without causing cracks.

The storage elastic modulus at 25 deg. C of the cured product formed by the liquid ink of Reference Example 4 having the composition excluding the silica particles from the liquid ink of Example 3 was substantially the same value as that of the cured product of Example 3. From this, it was confirmed that the storage elastic modulus of the cured product at 25 캜 was a value mainly reflecting the elastic modulus of the resin component excluding the inorganic filler.

One … The cured film (cured product)
10 ... materials

Claims (12)

A thermosetting resin composition comprising an organic polymer, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition,
Wherein a cured product having a storage elastic modulus at 25 占 폚 of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa is formed when the thermosetting resin composition is cured. The method according to claim 1,
Wherein the thermosetting resin composition comprises 50 mass% or more of the inorganic filler based on the mass of the thermosetting resin composition. 3. The method according to claim 1 or 2,
Wherein the organic polymer comprises an acrylic resin. The method of claim 3,
Wherein the acrylic resin has a glycidyl group. The method according to claim 3 or 4,
Wherein the acrylic resin has a weight average molecular weight of 400,000 to 1,800,000. 6. The method according to any one of claims 1 to 5,
Wherein the inorganic filler comprises silica particles. The method according to claim 6,
Wherein the silica particles are surface-treated with a silane coupling agent. 8. The method of claim 7,
Wherein the silane coupling agent has an amino group. 9. The method according to any one of claims 1 to 8,
Wherein the thermosetting resin comprises an epoxy resin, and the thermosetting resin composition further comprises a phenol resin. 10. The method of claim 9,
Wherein the epoxy resin comprises a biphenyl aralkyl type epoxy resin. 11. The method according to any one of claims 1 to 10,
A liquid ink used for applying a liquid ink to a polyimide film base material and curing the applied liquid ink to form a cured film for enhancing the rigidity of the polyimide film base material. 11. The method according to any one of claims 1 to 10,
A liquid ink used for applying a liquid ink to a flexible printed wiring board and curing the applied liquid ink to form a cured film for enhancing the rigidity of the flexible printed wiring board.

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