Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
  • H05K3/386—Improvement of the adhesion between the insulating substrate and the metal by the use of an organic polymeric bonding layer, e.g. adhesive
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/08—Macromolecular additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/04—Non-macromolecular additives inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J171/00—Adhesives based on polyethers obtained by reactions forming an ether link in the main chain; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J201/00—Adhesives based on unspecified macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J9/00—Adhesives characterised by their physical nature or the effects produced, e.g. glue sticks
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/14—Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/01—Dielectrics
  • H05K2201/0104—Properties and characteristics in general
  • H05K2201/0129—Thermoplastic polymer, e.g. auto-adhesive layer; Shaping of thermoplastic polymer
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/03—Conductive materials
  • H05K2201/0332—Structure of the conductor
  • H05K2201/0335—Layered conductors or foils
  • H05K2201/0355—Metal foils

Definitions

• the present invention relates to an adhesive composition
• an adhesive composition comprising, as a base, a resin component containing a thermoplastic resin, an epoxy resin and a curing agent, and an adhesive composition precursor as a raw material of the adhesive composition.
• an adhesive film for FPC (flexible printed circuit board) protective film an adhesive composition composed of a combination of various thermoplastic resins and a thermosetting epoxy resin has been known (see, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 9-132710, 9-125037, 6-256746, 5-
• an adhesive film formed from a composition comprising a phenoxy resin and/or an acrylic adhesive polymer as the thermoplastic resin, an epoxy resin and a curing agent is comparatively superior in properties such as heat resistance, adhesion to metal and the like, and has hitherto been considered to be particularly useful. It is also disclosed in the above publications to employ a polyester polyol resin and various elastomers as the thermoplastic resin. As the curing agent, dicyandiamide is frequently used because of its excellent curing potential.
• the acrylic adhesive polymer include a carboxyl group, a hydroxyl group or an epoxy group in the molecule.
• Japanese Unexamined Patent Publication (Kokai) Nos. 6-256746 and 5-339556 disclose compositions that reportedly have improved "repairing properties" due to a continuous epoxy resin phase and a dispersed phase of a phenoxy resin and a acrylic polymer.
• "Repairing properties” means that when circuit parts or circuits as the adherend are defective, the adhesive film can be easily removed from the adherend. After removing the adhesive film, non-defective circuit parts or circuits can be adhered to reconstruct the circuit. Accordingly, these publications do not disclose any means for effectively improving dimensional stability, impact resistance, flowability at the time of thermal bonding (preventing a flow large enough to cause squeeze-out), and adhesion.
• a nonflammable composition is normally formed by mixing an antimony pentaoxide powder with the other resin component.
• the antimony pentaoxide powder is comparatively inexpensive, and its average particle diameter is normally not less than 0.5 ⁇ m.
• Adhesive compositions comprising a thermoplastic resin, an epoxy resin and dicyandiamide have a drawback in that the stress produced during the heat curing process causes a large dimensional change. While reducing the dimensional change (i.e., improving the dimensional stability) is required for FPC protective film applications, it is very difficult to meet this requirement.
• the adhesive composition contains antimony pentaoxide powder
• the antimony pentaoxide is liable to be sedimented, due to its specific gravity, in a liquid mixture of the antimony pentaoxide, other resin component and solvent. It is difficult to obtain a uniform mixture.
• a non-uniform mixture reduces dimensional stability and adhesion, resulting in a drastic deterioration in the composition's utility as the adhesive for FPC protective film.
• the present invention provides an adhesive composition comprising a thermoplastic resin, an epoxy resin and a curing agent, and having improved utility as an adhesive for FPC protective film, particularly with respect to properties such as dimensional stability, impact resistance, flow resistance (resistance to flow) at the time of thermal bonding, and adhesion.
• the present invention also provides an adhesive composition precursor that can be advantageously used to provide such adhesive compositions.
• the present invention provides an adhesive composition
• a resin component containing a thermoplastic resin, an epoxy resin and a curing agent wherein: said thermoplastic resin contains a pressure sensitive adhesive polymer; and said resin component contains an inorganic colloid dispersed therein.
• the epoxy resin contains a brominated epoxy resin; said inorganic colloid is a colloid of antimony pentaoxide; and the total amount of said brominated epoxy resin and said colloid of antimony pentaoxide is within the range from 13 to 60% by weight, based on the total amount of said adhesive composition.
• the present invention provides an adhesive composition precursor which gives such an adhesive composition after drying. It comprises:
• a preferred method for producing the above adhesive comprises: (a) mixing a first resin solution obtained by dissolving an epoxy resin, a curing agent, and an optionally added thermoplastic resin other than a pressure sensitive adhesive polymer in a first solvent, with a second resin solution obtained by dissolving a pressure sensitive adhesive polymer in a second solvent to form a matrix resin solution; and
• the adhesive composition of the present invention is a composition comprising, as a base, a resin component containing a thermoplastic resin, an epoxy resin and a curing agent, containing a pressure sensitive adhesive polymer as the thermoplastic resin and an inorganic colloid dispersed in the resin component.
• the adhesive compositions of the present invention can effectively improve the following properties:
• Dimensional stability can be improved to such a degree that the dimensional change is not more than 0.1%.
• the impact resistance can be improved to such a degree that when a hole having a diameter of 10 mm is punched in a polymer film-adhesive film laminate (formed by applying an adhesive composition to a polymer film), no crack occurs at the periphery of the hole.
• the flow resistance at the time of thermal bonding can be improved to such a degree that when a hole (1 rnrn ⁇ X 1 mm2) is bored in an adhesive film, and a rolled copper foil having a thickness of 30 ⁇ m is placed on the adhesive film to cover the hole and then thermally bonded at 120°C under a pressure of 38 kg/cm ⁇ for 1 minute, the squeeze-out of the adhesive composition at the periphery of the hole is not more than 0.6 mm in length.
• the adhesion can be improved to such a degree that when an adhesive composition is used for bonding between a metallic foil such as copper foil and a film of a polymer such as polyimide, the adhesion strength can be effectively enhanced (e.g. peel strength can be increased to 500 kg/cm or more).
• One preferred aspect of the present invention provides an adhesive composition wherein: the epoxy resin contains a brominated epoxy resin; the inorganic colloid is a colloid of antimony pentaoxide; and the total amount of the brominated epoxy resin and the colloid of antimony pentaoxide is within the range from 13 to 60% by weight based on the total amount of all of the resin ingredients.
• brominated epoxy resin refers to an epoxy resin wherein a bromine atom is introduced into the molecule.
• the brominated epoxy resin has a structure in which one or more hydrogen atoms of the phenyl ring in a molecule of a bisphenol type epoxy resin is substituted with a bromine atom.
• the epoxy resin other than the "brominated epoxy resin” is particularly referred to as a “non-brominated epoxy resin” in the specification of the present application, and is distinguished from the brominated epoxy resin.
• the present invention resides in the combined use of an inorganic colloid and a pressure sensitive adhesive polymer in an adhesive composition that is based on an epoxy resin and a curing agent.
• the inorganic colloid can improve the dimensional stability and flow resistance during thermal bonding.
• the inorganic particles are in the form of a colloid, which will be defined hereinafter.
• the pressure sensitive adhesive polymer can cooperate with the inorganic colloid to improve dimensional stability and flow resistance, and synergistically combines with the inorganic colloid to improve impact resistance. Further, the inorganic colloid and the pressure sensitive adhesive polymer can improve the excellent adhesion of the adhesive composition based on the epoxy resin and the curing agent.
• the adhesive composition in accordance with this preferred aspect of the present invention is sufficiently nonflammable to pass level V0 of Underwriter's
• the additional, optional component includes (i) thermoplastic resins such as phenoxy resin, polyester polyol, etc., (ii) curing acclerators, and (iii) additives such as tackifier, plasticizer, etc., but is not limited thereto.
• the pressure sensitive adhesive polymer forms a fine phase separation structure having a size (e.g. diameter in the case of a spherical form) of about 1 nm to 1 ⁇ m in the adhesive composition.
• This fine structure and molecules of the other polymers (e.g. epoxy resin, phenoxy resin, etc.) in the adhesive composition are entangled in each other, thereby making it possible to improve the flow resistance at the time of thermal bonding and impact resistance at the same time.
• the fine structure has configurations other than a spherical form, such as an elliptical form or an indefinite form, the size of such fine structures should be measured as the longest dimension thereof, for example, the longitudinal axis in elliptical particles.
• the content of the pressure sensitive adhesive polymer is not limited so long as the effect on the present invention is not adversely affected, but is normally from 0.1 to 25% by weight, based on the total amount of the adhesive composition.
• the content is too small, the dimensional stability, impact resistance, flow resistance, and adhesion may not be improved.
• the content is too large, other features of the adhesive composition (e.g. nonflammability) are likely to be reduced.
• the preferred content of the pressure sensitive adhesive polymer is within the range of 1 to 10% by weight, based on the total amount of the adhesive composition.
• the term "pressure sensitive adhesive polymer” refers to a polymer showing pressure sensitive adhesion at a normal temperature (about 25°C).
• an acrylic polymer is preferred because it can effectively enhance adhesion.
• an alkyl acrylate-aromatic acrylate copolymer is preferred because the aromatic acrylate in the polymer molecule has good compatibility with the epoxy resin and can easily exert an interaction of entanglement.
• the adhesive composition contains a phenoxy resin
• the alkyl acrylate-aromatic acrylate copolymer has a good interaction with the phenoxy resin, thereby making it possible to improve the flow resistance at the time of thermal bonding as well as impact resistance.
• the weight ratio of the alkyl acrylate (A) to the aromatic acrylate (P) in the copolymer is not specifically limited so long as the copolymer shows pressure sensitive adhesion, but is preferably from 30:70 to 99:1, and particularly preferably from 40:50 to 90: 10.
• the amount of the aromatic acrylate in the copolymer is too small, the flow resistance at the time of thermal bonding and impact resistance are likely to be reduced.
• the amount of the aromatic acrylate is too large, the dimensional stability is likely to be reduced.
• alkyl acrylate examples include butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, and the like.
• aromatic acrylate examples include phenoxyalkyl acrylate and the like.
• the acrylic polymer can also contain other monomer units in place of or together with the alkyl acrylate or aromatic acrylate. These monomer units are, for example, alkyl methacrylate, (meth)acrylic carboxylic acid (e.g. acrylic acid, etc.), (meth)acrylic polycarboxylic anhydride, and alkoxy (meth)acrylate (e.g. acetoacetoxy acrylate, etc.).
• the adherend to which the adhesive composition is applied is metal, it is preferred that the acrylic polymer not contain substantial amounts of a carboxylic acid so as to prevent corrosion of the adherend.
• the inorganic colloid is normally contained in the dispersion in the form of colloidal particles, the colloidal particles are not sedimented by specific gravity and can be stably dispersed. Accordingly, the adhesive composition of the present invention formed by drying such a dispersion can achieve a state where the different components are uniformly mixed, thereby making it possible to improve peel strength and dimensional stability.
• the content of the inorganic colloid in the adhesive composition is not specifically limited so long as the effect of the present invention is not adversely affected, but is normally within the range of from 1 to 50% by weight. When the content is less than 1% by weight, the dimensional stability is likely to be reduced. On the other hand, when the content exceeds 50% by weight, the peel strength is likely to be reduced.
• the preferred content of the inorganic colloid is within the range of 2 to 45% by weight, based on the total weight of the adhesive composition.
• inorganic colloid normally refers to fine particles having an average particle diameter within the range of 1 to 100 nm.
• the inorganic particle sol is normally a mixture of (i) a dispersion medium and (ii) the inorganic colloid dispersed in the dispersion medium.
• the inorganic particle sol there can be used antimony pentaoxide sol, silica sol or the like.
• Resin Component The resin component normally comprises the following three components:
• the resin component comprises: (a) a phenoxy resin
• the phenoxy resin (a) is one of the components of the thermoplastic resin that contributes to improved adhesive strength.
• the intermolecular attraction between a hydroxyl group of a polymer molecule constituting the phenoxy resin and the flexibility of the resin itself contributes to an improved peel strength.
• the kind and amount of the phenoxy resin are preferably selected so that the glass transition temperature of the cured composition is at least 70°C. Consequently, the dynamic folding resistance of the cured composition is enhanced, thereby making it possible to effectively prevent breakage and peel-off of the adhesive layer in use.
• the non-brominated epoxy resin (b) increases the glass transition temperature of the cured composition by reacting with a curing agent such as dicyandiamide.
• a high glass transition temperature is advantageous for enhancing the heat resistance.
• the kind and amount of the non-brominated epoxy resin are also preferably selected so that so that the glass transition temperature of the cured composition does not reach 70°C or less.
• the non-brominated epoxy resin for example, there can be used epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, cresylic novolak epoxy resin, phenolic novolak epoxy resin and the like.
• the non-brominated epoxy resin is not an essential component. However, both types of epoxy resins are preferably included to enhance both adhesive strength and nonflammability.
• the brominated epoxy resin (c) enhances the nonflammability of the composition.
• the brominated epoxy resin also enhances the solubility of the phenoxy resin in a specific solvent (e.g. a mixed solvent containing methyl ethyl ketone and methanol).
• the mixed solvent containing methyl ethyl ketone and methanol has a comparatively large evaporation rate. Accordingly, a combination of the brominated epoxy resin and phenoxy resin is preferred for reducing the amount of the residual solvent in the adhesive composition (e.g. adhesive film, etc.) after drying and for providing a uniform mixture of the respective components.
• the brominated epoxy resin (like the non-brominated epoxy resin) reacts with the curing agent.
• the kind and amount of the brominated epoxy resin are preferably selected so that a good balance between the nonflammability of the composition, the solubility of the phenoxy resin, and the glass transition temperature (exceeding 70°C) of the composition after curing can be obtained.
• the curing agent (e) is a compound that can react with at least an epoxy resin to cure or crosslink the same.
• the curing agent is dicyandiamide or its derivatives. Dicyandiamide and its derivatives are superior in curing potential, and effectively enhance the storage stability of the adhesive composition and its precursor.
• the kind and amount of the curing agent are also preferably selected similar to the other resin components.
• the resin component can contain various optional components.
• the amount of these optional components is also preferably selected similar to the above other resin components.
• the content of the resin component other than the pressure sensitive adhesive polymer contained in the adhesive composition is not specifically limited so long as the effect of the present invention is not adversely affected.
• the phenoxy resin is the thermoplastic resin
• the content of (a) the phenoxy resin, (b) the non-brominated epoxy resin, (c) the brominated epoxy resin, and (d) the curing agent, each based on the total amount of all the resin ingredients, are respectively from 40 to 91.5% by weight (a), from 4 to
• the composition includes from 50 to 90% by weight (a), from 5 to 35% by weight (b), from 5 to 40% by weight (c), and from 0.5 to 5% by weight (d).
• the components are uniformly mixed in the adhesive composition (after drying) that is formed by using these resin components and a solvent (e.g. methyl ethyl ketone, methanol, ethyl alcohol, etc.).
• a solvent e.g. methyl ethyl ketone, methanol, ethyl alcohol, etc.
• the adhesive composition precursor is a raw material of the adhesive composition that provides the adhesive composition of the present invention.
• This precursor is normally composed of the resin component, particles of an inorganic colloid such as a colloid of antimony pentaoxide, and a solvent.
• the inorganic colloid is normally mixed with the other components in the form of a sol, and is uniformly dispersed in a vehicle of the resin components and solvent.
• the sol those prepared by dispersing colloidal particles in a dispersion medium containing an organic solvent are normally used.
• the solvent of the sol is preferably selected considering the solubility to the resin components. Among them, methyl ethyl ketone is particularly preferred because the dispersion stability of the sol (particles) in the precursor is not likely to be deteriorated.
• the concentration of the inorganic colloid in the adhesive composition precursor is normally within the range of 1 to 50% by weight.
• the adhesive composition precursor can be produced by various methods, and the method of producing the same will be described in detail below with reference to a case using a colloid of antimony pentaoxide as the inorganic colloid.
• an epoxy resin, a curing agent and a thermoplastic resin other than "a pressure sensitive adhesive polymer", such as phenoxy resin, which is optionally added, are dissolved in a first solvent to prepare a first resin solution.
• the pressure sensitive adhesive polymer is dissolved in a second solvent to prepare a second resin solution.
• the first and second resin solutions are mixed to prepare a matrix resin solution.
• Mixing can be carried out using, for example, a high-speed mixer, a planetary mixer, a homomixer, sand mill or the like.
• the solid content of the matrix resin solution is normally within the range of 5 to 70% by weight.
• an antimony pentaoxide sol is added to the matrix resin solution to prepare a uniform dispersion, using a suitable mixing means such as those described for preparing the matrix resin solution.
• the uniform dispersion thus obtained is the adhesive composition precursor. According to such a production method, there can be easily prepared a precursor containing antimony pentaoxide particles that are uniformly and stably dispersed in the resin components.
• the matrix resin solution preferably exhibits microphase separation.
• the first and second solvents are preferably different.
• Microphase separation in the adhesive composition formed by drying the precursor makes it possible to further enhance the dimensional stability, impact resistance, flow resistance at the time of thermal bonding, etc. of the adhesive composition.
• the microphase separated structure in the adhesive composition is a structure wherein one phase (the dispersed phase) forms islands having a size (diameter) of not more than 1 ⁇ m that are uniformly dispersed in a continuous sea (the continuous phase).
• the dispersed phase preferably contains the pressure sensitive adhesive polymer. In this case, the epoxy resin and curing agent are normally present in the continuous phase.
• thermoplastic resin other than the pressure sensitive adhesive polymer e.g., the phenoxy resin
• the thermoplastic resin is preferably present in the continuous phase.
• the epoxy resin and curing agent may be present in the continuous phase or dispersed phase.
• the solvent for the first resin solution should be a good solvent for the curing agent and the thermoplastic resin other than the pressure sensitive adhesive polymer (e.g., phenoxy resin).
• the solvent for the second resin solution should be a good solvent for the pressure sensitive adhesive polymer, but a poor solvent for the epoxy resin, curing agent and phenoxy resin.
• the first solvent is a mixture of methyl ethyl ketone (MEK) and methanol
• the second solvent is (i) an ester solvent alone, such as ethyl acetate, butyl acetate or the like, or (ii) a mixture of an ester solvent and a sub-solvent of the first solvent (e.g., toluene, isopropanol, acetone, MEK or blends thereof).
• the second solvent is a mixture of an ester solvent and a sub-solvent
• the weight ratio of the ester solvent (E) to the sub- solvent (S) i.e.
• (E:S) is within the range from 100:0 to 55:45.
• the weight ratio of methanol to MEK in the first solvent is normally from 0.005 to 0.4. When the ratio is less than 0.005:1, the solubility of dicyandiamide is lowered. On the other hand, when the ratio exceeds 0.4:1, the solubility of the thermoplastic resin is lowered. In both cases, it becomes more difficult to uniformly mix the components.
• the first solvent may contain solvents other than methyl ethyl ketone and methanol.
• it may contain alcohols such as ethanol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol, etc., or nitrogen-containing solvents such as acetonitrile, etc.
• ethanol has good solubility to dicyandiamide, an evaporation rate lower than that of methyl ethyl ketone, and does not drastically reduce the evaporation rate of the mixed solvent. Accordingly, a uniform coating can be obtained without lowering the drying rate of the coating.
• the adhesive composition precursor of the present invention is a dispersion having excellent storage stability because the inorganic colloid is stably dispersed in the matrix resin solution.
• the precursor composition is a dispersion wherein the two resin solutions cause stable microphase separation. Accordingly, the adhesive film of the adhesive composition of the present invention can be easily formed by purchasing such a stable dispersion, storing the dispersion, and then applying and drying it at the desired time.
• the adhesive composition precursor can contain various additives as far as the effect of the present invention is not adversely affected. Suitable additives are, for example, surfactants, viscosity adjustors and the like.
• the adhesive composition of the present invention can be used, for example, in the form of an adhesive film.
• the thickness of the film is normally within the range from 5 to 1,000 ⁇ m.
• the adhesive film can be produced by various methods that involve applying the adhesive composition precursor on a substrate and drying the precursor.
• the applying means there can be used the same means as in case of producing a normal adhesive film.
• suitable applying means include a knife coater, a bar coater, a die coater, an extruder and the like.
• the drying condition is not specifically limited. However, drying is normally performed at a temperature of 60 to 100°C for several seconds to 1 hour so that the residual solvent does not remain and the curing reaction of the composition does not proceed excessively at the time of drying.
• plastic films such as polyimide film, polyester film, etc. and metal foils such as copper foil, aluminum foil, etc.
• the invention is not limited to these.
• it is normally employed as an adhesive sheet or adhesive film comprising a layer of an adhesive film and a substrate.
• the release film may be removed before use and an adhesive film alone can also be used.
• the adhesive film is laminated on the adherend and bonding between them is completed by a thermal bonding operation including heating at 100 to 180°C for 0.1 to 2 minutes under a pressure of from 2 to 50 kg/cm ⁇ - After the completion of the thermal bonding operation, the following heating operation at 150 to 180°C for 1 to 5 hours can also be performed.
• the thickness of the adhesive film is preferably adjusted so that squeeze-out of the composition component from the film end hardly arises.
• the thickness of the adhesive film is normally from 10 to 2,000 ⁇ m.
• the formulation of the adhesive composition is preferably selected so that the tensile storage modulus at 60°C of the cured adhesive film is not less than 1010 dyn/cm ⁇ . Consequently, it is possible to obtain an adhesive film having high dynamic folding resistance at 60°C, which is suitable as an adhesive for FPC protective film.
• the adhesive for FPC protective film is preferably selected so that the shrinkage rate of the adhesive film after the completion of curing is not more than 0.1%. This shrinkage rate is a percentage of a reduction in size after curing to the size before curing.
• Example 1 Preparation of adhesive composition precursor (dispersion) and formation of adhesive film.
• a phenoxy resin trade name: YP50S, number-average molecular weight: 1,180, weight average molecular weight: 58,600, manufactured by Tohto Kasei Co., Ltd.
• a brominated epoxy resin trade name YDB400, epoxy equivalent of about 400, manufactured by Tohto Kasei Co., Ltd.
• Dicy dicyandiamide
• the acrylic pressure sensitive adhesive polymer as the second resin solution is an acrylic acid unit- containing copolymer and can be available as a solution dissolved in a mixed solvent of ethyl acetate and toluene (65:35).
• an antimony pentaoxide sol (trade name: Sun Colloid AME-130, particle diameter: 5 to 50 nm, solid content: 30% by weight, dispersion medium: methyl ethyl ketone, manufactured by Nissan Chemical Co., Ltd.) was added.
• An adhesive composition precursor of this example was obtained as a uniform dispersion.
• the composition of the resulting adhesive composition precursor is as described in Table 1 below for reference.
• the ratio of methanol (MeOH) to methyl ethyl ketone (MEK) in a solvent included in this adhesive composition precursor, i.e. MeOH/MEK was
• the adhesive composition precursor of this example was evaluated with respect to the dispersion stability. The results show that the formed microphase separation is stably maintained and the dispersion stability is good. The dispersion state was satisfactory enough to recover the original state by shaking several times by hand, even after 30 days.
• the resulting dispersion was uniformly applied on a substrate film of any one of the following plastic films: a PET film subjected to a releasing treatment or a polyimide film (trade name: Kapton V, thickness: 25 m), and then dried at 90°C for 30 minutes.
• Tg Glass transition temperature
• a rolled copper foil having a thickness of 30 ⁇ m was laminated on the adhesive surface of an adhesive film with a polyimide film prepared in the same manner as described above, and they were thermally bonded at 120°C under a pressure of 20 kg/cm ⁇ for 1 minute. Subsequently, the resulting laminate was heat-treated at 170°C for 2 hours to obtain a test piece.
• the copper foil of this test piece was peeled off at a peel angle of 180° and a peel rate of 50 mm/min and the integrated average value of the resulting value was taken as an adhesive strength (peel adhesive strength, g/cm).
• the adhesive composition precursor and adhesive film of this example were respectively observed by an optical microscope (magnification: x 500). As a result, it has been found that both of them have a microphase separated structure, wherein a fine "separated phase" having a size of submicron order or less is uniformly dispersed in a "continuous phase". It is considered that such a microphase separated structure effectively contribute to an improvement in dimensional stability, impact resistance (die punching properties) and flowability at the time of thermal bonding.
• an adhesive composition precursor of this example was prepared.
• the adhesive composition precursor of this example gave an adhesive film having the same performances as those of Example 1 when using it immediately after preparation. However, the storage stability was not good and the same microphase separated structure as that of Example 1 could be maintained only for several hours.
• an adhesive composition precursor and adhesive film of this example were prepared.
• the pressure sensitive adhesive polymer used in this example is that (trial preparation No. EX01) obtained by reacting in an ethyl acetate solution according to a solution polymerization method, and was a copolymer of 2- methylbutyl acrylate and an acrylic acid (weight ratio: 90:10).
• an ethyl acetate solution having a concentration of 30% by weight was used as a second resin solution.
• the adhesive composition precursor of this example had good dispersion stability, similar to Example 1.
• the adhesive composition precursor and adhesive film of this example had the same microphase separated structure as that of Example 1. Furthermore, the adhesive film of this case was evaluated in the same manner as that described in Example 1. The results are shown in Table 1 below.
• an adhesive composition precursor and adhesive film (adhesive composition) of each example were prepared.
• the adhesive composition precursor of each example had good dispersion stability, similar to Example 1.
• the adhesive composition precursor and adhesive film of each example had the same microphase separated structure as that of
• Example 1 Furthermore, the adhesive film of each example was evaluated in the same manner as that described in Example 1. The results are shown in Table 1 below. The details of the resin components used newly in each example are as listed below.
• PKHM30 polyester polyol-containing phenoxy resin, (trade name: PKHM- 30, containing about 30% by weight of polyester polyol, manufactured by Union Carbide Co.).
• Pressure sensitive adhesive polymer (second resin solution)
• Examples 3 and 4 product obtained by solution polymerization (trial preparation No. EX02), copolymer of phenoxyethyl acrylate and acrylic acid (weight ratio 9:1).
• Examples 5 and 6 the same one as that of Example 1 is used.
• Example 8 copolymer having a hydroxyl group in the molecule, SKI 435 manufactured by Sohkent Kagaku Co., Ltd., available as a solution containing a mixed solvent of ethyl acetate and toluene (59:41).
• Example 9 the same one as that of Example 1 is used.
• Example 11 product obtained by solution polymerization (trial preparation
• Example 13 product obtained by solution polymerization (trial preparation No. EX07), copolymer of butyl acrylate and phenoxyethyl acrylate (weight ratio 50:50).
• an adhesive composition precursor and adhesive film (adhesive composition) of each example was prepared.
• the adhesive film of each example was evaluated in the same manner as that described in Example 1. The results are shown in Table 1 below. Since the pressure sensitive adhesive polymer is not used in these comparative examples, the die punching properties are particularly inferior to Examples 1 to 14.
• this adhesive composition can be advantageously used as an adhesive for FPC protective film.

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• 1998
  • 1998-07-28 JP JP10212505A patent/JP2000053934A/ja active Pending
• 1999
  • 1999-06-15 EP EP99933514A patent/EP1117747A1/en not_active Withdrawn
  • 1999-06-15 WO PCT/US1999/013486 patent/WO2000006661A1/en active IP Right Grant
  • 1999-06-15 KR KR1020017001177A patent/KR100609804B1/ko not_active IP Right Cessation
  • 1999-06-15 CN CNB99810521XA patent/CN1156549C/zh not_active Expired - Fee Related
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