Classifications

• • 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
  • C09J157/00—Adhesives based on unspecified polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/22—Plastics; Metallised plastics
• • 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
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
• • 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
  • C08L2666/20—Macromolecular compounds having nitrogen in the main chain according to C08L75/00 - C08L79/00; Derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • 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
  • C09J2433/00—Presence of (meth)acrylic polymer
• • 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
  • C09J2467/00—Presence of polyester
• • 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
  • C09J2469/00—Presence of polycarbonate

Definitions

• the present invention relates to an adhesive composition and an adhesive sheet, and in more detail to an adhesive composition having pressure sensitivity including an adhesive polymer and a nonadhesive polymer, and to an adhesive sheet.
• An adhesive sheet equipped with an adhesive layer comprising a pressure sensitive adhesives on at least one of main surfaces of a substrate may be easily and strongly stuck only by pressure being applied, and thus since sticking work to adherend can be easily done manually, these adhesive sheets are used widely.
• pressure sensitive adhesives constituting adhesive layers of adhesive sheets
• a pressure sensitive adhesive having adhesive polymers as principal component is widely known, and various types have been developed.
• a pressure sensitive adhesives including a) acrylate copolymer 100 mass parts obtained from a monomer mixture including one or more kinds of mono functional acrylates having non-tertiary alkyl group having 1 to 14 carbons about 70 to 98 percent by weight, and a polar monomer of approximately 30 to 2 percent by weight, b) a plasticizer of 2 to 10 mass parts are known.
• pressure sensitive adhesives wherein acrylate copolymers included as monomer units (repetition units) originating in mono functional acrylates at comparatively large percentage in molecule, almost all copolymers show a glass transition point (Tg) by a dynamic viscoelasticity measuring method of -5°C or less.
• plasticizers such as polyethylene oxides and adipates, may also be added, the pressure sensitive adhesives are excellent in low-temperature performance as low-temperature adhesive property.
• adhesive films are known wherein tack of adhesive layers is suppressed.
• an adhesive film in which good positioning property at ordinary temperature is realized by covering a part of the adhesive layer surface by non-tacky grains, such as inorganic grains and glass beads.
• a pressure sensitive adhesive is known in which a nonadhesive polymer comprising substantially linear polycaprolactones having a molecular weight of approximately 3,000 to approximately 342,000 etc. is included in addition to pressure sensitive adhesive basic resin comprising adhesive polymers, such as acrylic derived polymers, and non-tacky grains comprising inorganic grains, such as silica, is included to mitigate tack at ordinary temperature effectively and to improve positioning property in sticking process.
• thermo sensitive adhesiveness An adhesive composition with thermo sensitive adhesiveness is known in which an adhesive polymer having two functional groups, hydroxy group and phenyl group, in a molecule, and crystalline polycaprolactone serving as a nonadhesive polymer are included. Compatibility between the adhesive polymer and the polycaprolactone are improved and tack on a surface of the adhesive at ordinary temperature is effectively mitigable.
• the present invention provides an adhesive composition that effectively enhances pressure sensitive adhesivity at low temperatures and tack suppression effect at the same time, which makes easy an accurate positioning of the site for sticking, and which can be easily stuck by press fitting even in an environment of low temperature less than 0°C, and at providing an adhesive sheet constituted with the composition as an adhesive layer.
• viscoelasticity behavior of the adhesive polymer has direct influence over pressure sensitivity required for adhesive composition, and that selection of a composition having a glass transition point obtained from viscoelasticity behavior in a specific range demonstrates appropriate pressure sensitivity even at low temperature.
• an adhesive composition having pressure sensitivity including an adhesive polymer and a nonadhesive polymer, wherein the adhesive polymer has a glass transition point by a dynamic viscoelasticity measuring method of -60°C to -5°C, and the nonadhesive polymer has a glass transition point by a differential scanning calorimeter of -5°C or less, and a fusing point of higher than 25°C by a differential scanning calorimeter, and also has compatibility with the adhesive polymer in uncrystallized state.
• an adhesive composition of the present invention has a probe tack lower than 7N, measured by a method based on ASTM D2979 under conditions of 25°C, contact pressure of 100 g/cm 2 , contact time of 1 second, and releasing speed of 10 mm/second is lower than 7N, and a 180 degrees releasing strength measured at a releasing speed of 300 mm/minute, in -5°C environment is 20 N/25 mm or more, after being stuck to a melamine baking finish plate and being left to stand for 5 minutes under -5°C environment.
• an adhesive polymer preferably has at least one alkyl group having 4 to 8 carbons including at least one butyl group, and at least one carboxyl group, and monomer units including alkyl groups having 4 to 8 carbons in a percentage of 60 to 99 mole % in all molecules.
• an adhesive polymer preferably has a polycaprolactone skeleton or a polycarbonate skeleton in the molecule.
• a method for manufacturing an adhesive composition comprises the steps of: (a) preparing a first solution by dissolving an adhesive polymer whose glass transition point by a dynamic viscoelasticity measuring method is -60 to -5°C in a solvent, (b) preparing a second solution by dissolving in a solvent a nonadhesive polymer in which a glass transition point by a differential scanning calorimeter is -5°C or less, a fusing point by a differential scanning calorimeter is higher than 25 °C, and the nonadhesive polymer being compatible with the adhesive polymer in uncrystallized state, (c) mixing the first solution and the second solution approximately uniformly, and (d) drying an obtained mixed solution.
• a low temperature applicable adhesive sheet comprising a substrate, and an adhesive layer comprising the above described adhesive composition
• the substrate includes a polymer film, and has a breaking elongation of 50% or more at -5°C at an elastic stress rate of 300 rnm/min and a 50% elongation stress of 10 to 200 MPa at an elastic stress rate of 300 rnm/min at -5°C.
• Adhesive Composition An adhesive composition of the present invention is characterized by that the composition includes an adhesive polymer and a nonadhesive polymer, a glass transition point of the adhesive polymer by a dynamic viscoelasticity measuring method is -60 to -5°C, a glass transition point of the nonadhesive polymer by a differential scanning calorimeter is -5°C or less, a fusing point by a differential scanning calorimeter is higher than 25°C, and also has compatibility with the adhesive polymer in uncrystallized state.
• an adhesive sheet with an adhesive layer constituted by the above described composition concerned may easily be released after stuck to adherend face lightly to enable an easy accurate positioning to a site for sticking, and at the same time may easily be stuck by being stuck by press fitting towards an adherend face in an environment of comparatively wide temperature range (a range of -5 to 25 °C included) including low temperatures of 0 or less °C.
• a glass transition point (Tgi) of an adhesive polymer in the present invention by a dynamic viscoelasticity measuring method is -60 to -5°C. If a glass transition point (Tgi) of an adhesive polymer by a dynamic viscoelasticity measuring method exceeds -5°C, low-temperature adhesive property, especially pressure sensitivity at temperature of less than 0°C will fall, and on the other hand tack effect cannot be effectively suppressed if a glass transition point (Tg by a dynamic viscoelasticity measuring method is less than -60°C, and as a result after being stuck toward adherend face lightly, it does not release easily to make accurate positioning of site for sticking difficult.
• Adhesive polymers whose glass transition point (TgO by a dynamic viscoelasticity measuring method is -60 to -5°C involved, for example, polymers, such as acrylic derived polymes, nitrile-butadiene derived copolymers (NBR etc.), styrene-butadiene derived copolymers (SBR etc.), uncrystallized polyurethanes, and silicone derived polymers, or polymers with two or more of the above described kinds mixed.
• an adhesive polymer of the present invention a polymer having one or more alkyl groups having 4 to 8 carbons including at least one butyl groups, and one or more carboxyl groups is preferable among polymers having the above described characteristics.
• an adhesive polymer having such substituents has a very high compatibility with a nonadhesive polymers at temperatures higher than fusing point of the nonadhesive polymers, and thus phenyl group is not needed to increase compatibility with nonadhesive polymer, a glass transition point (Tg]) by a dynamic viscoelasticity measuring method is easily controlled in the above described range.
• a glass transition point (Tg 2 ) of an adhesive polymer in order for a glass transition point (Tg 2 ) of an adhesive polymer to be controlled very easily in a range of -5°C or less, it is preferable that many butyl groups are included in all alkyl groups having 4 to 8 carbons, and specifically, it is preferable that 50 to 100 mol % in alkyl group having 4 to 8 carbons are butyl groups.
• monomer units including alkyl group having 4 to 8 carbons is preferably include 60 to 99 mol % in all of molecules, more preferably 65 to 98 mol % in all of the molecules, and still more preferably 70 to 95 mol % in all of the molecules.
• a percentage of the monomer unit including alkyl group having 4 to 8 carbons is less than 60 mol %, low-temperature adhesive property of the adhesive composition may not be effectively raised.
• a content of the monomer unit including alkyl group having 4 to 8 carbons exceeds 99 mol %, a content percentage of a monomer unit including active hydrogen containing group may be decreased, and so that compatibility between the nonadhesive polymer and the adhesive polymer may be decreased.
• a molecular weight if an adhesive polymer used in the present invention is in a range where predetermined adhesive strength is demonstrated, usually it may be set to have a weight average molecular weight of 10,000 to 1,000,000.
• weight average molecular weight means a styrene converted molecular weight by a GPC method.
• a cross-linked polymer may be used as an adhesive polymer to increase heat resistance, and to prevent adhesive deposit.
• Cross linkage may be formed through functional groups, such as hydroxyl groups other than alkyl group and carboxyl group in the adhesive polymer, epoxy groups, and radiation-induced cross linking property functional groups, and may be formed through carboxyl groups.
• a cross linkage structure is typically formed using cross-linking agents, and it is preferable that a structure is formed by reacting suitable cross-linking agents based on types of cross-linking functional groups of an adhesive polymer so that sufficient cross linking density to increase heat resistance as an adhesive and adhesive deposit prevention effect may be obtained.
• a cross-linking functional group utilized in cross-linking is a carboxyl group
• a cross linkage structure is formed using bis amide derived cross-linking agents or epoxy resin derived cross-linking agents as cross-linking agents.
• a cross linkage structure may also be formed using isocyanate derived cross-linking agents in a range that does not impair effect of the present invention.
• Epoxy resin derived cross-linking agents for example, bisphenol A type epoxy resins, bisphenol F type epoxy resins, cresol novolak type epoxy resins, phenol novolak type epoxy resins, etc. also be used.
• the epoxy equivalent of epoxy resin derived cross-linking agents is usually 70 to 400, and preferably 80 to 300.
• Bis amide derived cross-linking agents for example, bisaziridine derivatives of dibasic acid, such as iso phthaloyl bis(2 -methyl aziridine), etc. may also be used.
• bisamide derived cross-linking agents may react at comparatively low temperature with adhesive polymer having carboxyl groups, it is especially preferable to easily obtain sufficient cross-linking density.
• cross-linking component unit is included at 0.01 to 20 mass % in the adhesive composition, and is more preferable that 0.05 to 10 mass %.
• tackifiers may also be used with adhesive polymers as in conventional pressure sensitive adhesives.
• An adhesive polymer used in the present invention may be prepared by methods known to those skilled in the art.
• acrylic derived adhesive polymer may be obtained by polymerizing a mixed monomer including (a) (meth)acrylic monomer that has alkyl group having 4 to 8 carbons in molecule, and (b) (meth)acrylic monomer that has carboxyl group in molecule.
• copolymerization may be carried out by standard methods of polymerization, such as solution polymerization.
• the above described components (a) and (b) are included in all monomers, and specifically it is preferable that the above described components (a) and (b) are included 65 mol % or more in sum total in all monomers, and more preferable that 70 mol % or more.
• a glass transition point (Tg 2 ) of a nonadhesive polymer by a differential scanning calorimeter used for the present invention is -5°C or less.
• a glass transition point (Tg 2 ) by a differential scanning calorimeter exceeds -5°C, low-temperature adhesive property, and particularly the pressure sensitivity at a temperature of less than 0°C will decline, and therefore application to adhesive film used outdoors for an object, such as advertisement, will become difficult.
• a glass transition point (Tg 2 ) is preferably -70°C or more.
• a glass transition point as determined by a differential scanning calorimeter of a nonadhesive polymer is preferably no more than a glass transition point (Tg as determined by a dynamic viscoelasticity measuring method of an adhesive polymer, and more preferably a Tg difference (Tgi- Tg 2 ) that is in a range of 20 to 65°C.
• Tack suppression effect can be increased easily, almost without disturbing adhesive property including low-temperature adhesive property of the adhesive polymer, if the glass transition point of both polymers is in such a relationship.
• a nonadhesive polymer as used in the present invention is a crystalline polymer with a fusing point by a differential scanning calorimeter higher than 25°C.
• a fusing point as determined by a differential scanning calorimeter is 25°C or less, tackiness is substantially demonstrated at ordinary temperatures and tack of the composition obtained may not be suppressed effectively.
• compatibility with an adhesive polymer may fall when the fusing point is too high, and it is preferable that the fusing point of the nonadhesive polymer be 100°C or less.
• a nonadhesive polymer in the present invention has compatibility with an adhesive polymer in uncrystallized state.
• a nonadhesive polymer having no compatibility with an adhesive polymer will interfere with the low-temperature performance of the adhesive polymer, and, as a result, the low-temperature adhesive property of a composition will fall.
• “compatibility” may be determined by three factors,
• a film adhesive film-like adhesive comprising an adhesive composition used in the present invention, and having a thickness in a range of 20 to 60 ⁇ m
• a film adhesive is heated at a temperature no less than a fusing point of an nonadhesive polymer and compared with a film adhesive that is heated at a temperature less than the fusing point.
• the nonadhesive polymer usually forms a plurality of fine crystals.
• a phase of the nonadhesive polymer is dispersed in matrix phase including the adhesive polymer.
• haze value measured using a color difference meter shows at least 5% (usually 20% or less).
• the nonadhesive polymer melts, and so that a state where the nonadhesive polymer and the adhesive polymer are melted mutually is shown to lower the haze value and the film adhesives seem to be almost transparent.
• a haze value hardly changes. In such a case, smaller haze value means better compatibility. Therefore, in the case that the nonadhesive polymer and the adhesive polymer melt mutually, a haze value measured using a color difference meter is preferably 2% or less, and especially preferably 2% or less.
• a film adhesive comprising an adhesive composition of the present invention is placed between two polarizing plates made to intersect perpendicularly and observation is performed.
• micro crystal of nonadhesive polymer rotates polarization plane of light coming into the film adhesive, and the light is transmitted through two polarizing plates. Since the direction of crystal axis is usually random, a crystal that works to transmit incident light through two polarizing plates by rotating polarization plane of light by exactly 90 degrees and a crystal through which light cannot transmit may exist at the same time.
• Non-limiting examples of a nonadhesive polymer used in the present invention has a glass transition point (Tg 2 ) as determined by a differential scanning calorimeter of -5°C or less and a fusing point measured by a differential scanning calorimeter being higher than 25°C.
• Such polymers are compatible with the adhesive polymer in an uncrystallized state, and include but are not limited to polyester polyols, such as poly caprolactones; polyols, such as polycarbonate polyols, or crystalline polyurethanes obtained by polymerizing these polyols and diisocyanate compounds. In addition, these polymers may be used independently or may be used in combination.
• Additional nonadhesive polymers used in the present invention include, a polymer that has an alkylene skeleton of 4 to 6 carbon atoms in the molecule with the promise that the polymer has (1) a high degree of crystallinity, and (2) an effective fuming point such that the polymer is not tacky at room temperature (3 is soluble in organic solvents and (4) is compatible with the adhesive polymer. Furthermore, a nonadhesive polymer having poly caprolactone skeleton or polycarbonate skeleton is more preferable. A nonadhesive polymer having a polycarbonate skeleton in molecule is preferable and generally, water resistance and anti-hydrolysis property of an adhesive composition.
• An adhesive composition in the present invention includes the above described adhesive polymer and nonadhesive polymer, wherein tack suppression and low-temperature adhesive property of the adhesive composition are simultaneously attained.
• An adhesive composition in the present invention specifically has a probe tack measured by a method based upon ASTM D2979 under conditions of 25°C, a contact pressure of 100 g/cm 2 , a contact time of 1 second, and a releasing speed of 10 mm/sec
• probe tack (hereinafter referred to as "probe tack” simply) that is preferably lower than 7 N, and more preferably is 6N or less, and especially preferably is 5 N or less.
• a probe tack in this range provides for easier release of an adhesive sheet and also makes it easier to attain accurate positioning of the adhesive sheet.
• lower limit of a probe tack is not especially limited as long as pressure sensitivity at low temperature is not impaired, it is preferably 2 N or more in view of easy temporary sticking process obtained, and more preferably 3 N or more.
• An adhesive composition of the present invention preferably has a 180 degrees releasing strength (hereinafter referred to as simply "-5°C releasing strength") of 20 N/25 mm or more measured at a 300 mm/minute releasing speed at -5°C after being left as it is for 5 minutes while adhering to a melamine baking finish plate at -5°C, more preferably 22 N/25 mm or more, and especially preferably 23 N/25 mm or more.
• -5°C releasing strength 180 degrees releasing strength
• 20 N/25 mm or more measured at a 300 mm/minute releasing speed at -5°C after being left as it is for 5 minutes while adhering to a melamine baking finish plate at -5°C, more preferably 22 N/25 mm or more, and especially preferably 23 N/25 mm or more.
• an upper limit of a -5°C release strength is not especially limited, preferably it is 50 N/25 mm or less in view of making tack control easier.
• a suitable combination of a nonadhesive polymer and an adhesive polymer may suitably be selected so that the above described characteristics, such as tack suppression and low-temperature pressure sensitivity, may be demonstrated.
• a probe tack ratio (TAf/TBf) that is a ratio of a probe tack (TAf) of an adhesive composition including a nonadhesive polymer 10 mass parts to an adhesive polymer 90 mass parts, to a probe tack (TBf) of an adhesive composition including the adhesive polymer concerned independently is less than 0.9, and preferably 0.88 or less, and (ii) a probe tack ratio (TAf/TBf) that is a ratio of a probe tack (TAf) of an adhesive composition including a nonadhesive polymer 10 mass parts to an adhesive polymer 90 mass parts, to a probe tack (TBf) of an adhesive composition including the adhesive polymer concerned independently is less than 0.9, and preferably 0.88 or less, and (ii) a probe tack ratio (TAf/TBf) that is a ratio of a probe tack (TAf) of an adhesive composition including a nonadhesive polymer 10 mass parts to an adhesive polymer 90 mass parts, to
• -5°C releasing strength ratio that is a ratio of a -5°C releasing strength (PAf) of the adhesive composition including a nonadhesive polymer 10 mass parts to an adhesive polymer 90 mass parts to a -5°C releasing strength (PBf) of an adhesive composition including the adhesive polymer concerned independently is 0.7 or more, and preferably 0.8 or more.
• a probe tack ratio (TAf/TBf) exceeds 0.9
• tack suppression effect at normal temperature may not necessarily be enough, and accurate positioning of the site for sticking of an adhesive sheet may become difficult.
• a -5°C releasing strength ratio (PAf/PBf) becomes less than 0.7
• low-temperature adhesiveness of a composition especially pressure sensitivity at a temperature less than 0°C in an environment at low temperature falls, and sometimes sticking of an adhesive sheet may become difficult.
• an adhesive polymer and a nonadhesive polymer are present in a ratio so that effective tack suppression and low-temperature press fitting nature may be demonstrated.
• an adhesive polymer is included 70 to 97 mass % in an adhesive composition, it is more preferable 75 to 95 mass %, and it is especially preferable
• the nonadhesive polymer is preferably included 2 to 29 mass % in an adhesive composition, more preferably 4 to 24 mass %, and especially preferably 5 to 19 mass %.
• an adhesive composition of the present invention a first solution with the above described adhesive polymer dissolved therein, and a second solution with a nonadhesive polymer dissolved therein are mixed to obtain a mixed solution with the adhesive polymer and the nonadhesive polymer almost uniformly dispersed therein. Subsequently, this mixed solution is preferably dried to obtain the adhesive composition.
• an adhesive composition obtained by such a manufacturing method when an adhesive polymer and a nonadhesive polymer form mutual phase separated structure at a temperature less than a fusing point of a nonadhesive polymer, a phase separated structure where phase including large amount of the nonadhesive polymer is finely and uniformly dispersed is obtained, and thereby a nonadhesive polymer may exist almost without blocking adhesive property (low-temperature releasing strength etc.) of an adhesive polymer, and tack control effect is easily improved.
• the adhesive polymer and nonadhesive polymer can be dissolved low molecular organic solvent having 4 to 8 carbons that has alkyl groups conjugating with benzene ring or carbonyl group in a molecule.
• organic solvents included but are not limited to for example, methyl ethyl ketone, ethyl acetate, toluene, etc.
• Mixing process of a first solution and a second solution may be performed by conventional methods using mixing equipments, such as a homogeneous mixer and a planetary mixer, and thus each polymer may be uniformly dissolved or dispersed.
• Drying process of mixed solution obtained may usually be performed at temperatures of 60 to 180°C for dozens of seconds to several minutes.
• a third solution containing a cross-linking component is added to a mixed solution of the first solution and the second solution, and then all solutions are mixed together uniformly.
• additives may be included, provided the additives do not diminish the effectiveness of the adhesive composition. If such additives are used, they are present in amount consistent with the use as known to those skilled in the art.
• additives include but are not limited to viscosity regulators, defoaming agents, leveling agents, UN absorbents, antioxidants, pigments, anti-mold agent, elastic minute balls comprising an adhesive polymer or nonadhesive rubber derived polymer, tackifiers, catalysts promoting cross-linking reaction, etc. 2.
• a low temperature applicable adhesive sheet in the present invention comprises a substrate and an adhesive layer made of an adhesive composition and such adhesive composition is disposed on at least one of major surface of the substrate.
• Substrates used in the present invention include for example, a substrate made from paper, coated paper, metal films, and polymer films. Substrates comprising a polymer film are preferred.
• Polymer films comprising one or more synthetic polymer including at least one kind selected from a group of non-crystalline polyesters, plasticized polyesters, polyurethanes, polyolefins, and ethylene-acrylate copolymers etc. are preferable. Furthermore, polyolefins, especially ionomers, or ethylene- vinyl acetate copolymer modified polyolefins are more preferable.
• a substrate used in the adhesive sheet of the present invention preferably has 50% or more of low-temperature elongation at -5°C and by elastic stress rate of 300 mm/minute, more preferably 60% or more, and especially preferably 70% or more.
• low-temperature elongation represents a ratio of an elongation of the substrate at breaking by strain to a length of a strain direction of a substrate before straining. It is preferable that a substrate used in an adhesive sheet of the present invention further has 50% elongation stress of 10 to 200 MPa at -5°C and in 300 mm elastic stress rate, it is more preferable that 12 to 150 MPa, and it is especially preferable that 15 to 100 MPa.
• 50% elongation stress is 200 MPa or more, there is a possibility that neither irregularity of an adherend nor curve may not be followed at a low temperature of -5°C, and on the other hand, if the above described 50% elongation stress is less than 10 MPa, the elongation of a substrate will become excessively large, and there is a possibility that wrinkle may be given on a sheet or a sheet may fracture by an ordinary temperature hand work.
• 50% elongation stress represents a stress when a substrate is elongated by 50%.
• a thickness of a substrate is generally based on the application and such thickness is generally 5 to 500 ⁇ m, and preferably 10 to 300 ⁇ m.
• a substrate used in an adhesive sheet of the present invention may transmit visible light and ultraviolet radiation, and may also be a substrate reflecting light, such as a retroreflection sheet. It may be colored, or the sheet may contain one or more images and such an adhesive sheet may be used as an ornamental sheet or a marking film.
• a substrate used in an adhesive sheet of the present invention may include an adhesive layer on at least one main surface, a liner may also be included on at least one main surface of the substrate, and the adhesive layer may be indirectly prepared via this liner.
• a liner having paper or plastics film as principal component may be included.
• the paper liner usually has releasing coatings (releasing layer), such as a polyethylene coat and a silicone coat on a surface of paper.
• releasing coatings such as a polyethylene coat and a silicone coat
• under coats such as clay coat and a polyethylene coat, are present between the paper and the releasing coating layer.
• Liners with fine irregularity formed on the stripping face are preferable as liners used in the present invention.
• irregularity transferred from the irregularity of a liner stripping face can be prepared on a surface (adhesion face) of an adhesive layer prepared on a liner.
• minute glass beads etc. can be disposed in a predetermined position of an adhesive layer by giving a desired pattern to the irregularity of a liner releasing face.
• an adhesive layer may be formed on the liner and the minute glass beads will be diffused onto the adhesive layer.
• irregularity of a liner stripping face may be arranged with regularly repeated pattern, and may be irregularity having a rough surface with irregular pattern.
• a first solution containing an adhesive polymer is in dissolved state and a second solution similarly including a nonadhesive polymer is in dissolved state are mixed together, the mixed solution is applied on a substrate or a liner. This mixture is dried to form an adhesive layer on the liner.
• predetermined quantity of a third solution comprising a cross-linking component may be added to the mixed solution obtained by mixing first solution and the second solution.
• a solvent dissolving each polymer is preferably a comparatively low molecular organic solvent having 4 to 8 carbons that has benzene ring or carbonyl group, and alkyl group conjugating to the benzene ring or the carbonyl group in a molecule so that it may have a good compatibility to both of an adhesive polymer and a nonadhesive polymer used in an adhesive composition of the present invention and an adhesive polymer and a nonadhesive polymer can be uniformly dissolved in a mixed solution.
• organic solvents for example, methyl ethyl ketone, ethyl acetate, toluene, etc. may be mentioned.
• an adhesive polymer has one or more alkyl groups having 4 to 8 carbons, and one or more carboxyl groups in a molecule, a percentage of a monomer unit comprising the alkyl groups having 4 to 8 carbons included in the adhesive polymer molecule is 60 to 99 mol %, and it is preferable that the one or more alkyl groups having 4 to 8 carbons always include a butyl group, and that a nonadhesive polymer has alkylene skeleton having 4 to 6 carbons in a molecule.
• an adhesive polymer and a nonadhesive polymer have uniform and minute phase separated structure, and thereby a nonadhesive polymer may exist almost without blocking adhesive property of an adhesive polymer, and tack control effect is easily improved in an adhesive composition comprising such an applied film.
• a coating material that forms an adhesive layer can be formed by dissolving or dispersing each material uniformly using mixing equipments, such as a homogeneous mixer and a planetary mixer. Drying process at a time of forming an adhesive layer is usually performed at a temperature of 60 to 180°C. Drying time is usually dozens of seconds to several minutes.
• An adhesive layer usually has a thickness of 5 to 1 ,000 ⁇ m, preferably 10 to 500 ⁇ m, and especially preferably 15 to 100 ⁇ m.
• Well-known means such as a knife coater, a roll coater, a die-coater, and a bar coater, may be used for an application means.
• a nonvolatile component in a first solution, a second solution, and a mixed solution that mixes these solutions approximately in a uniform state is preferably 10 to 70 mass %.
• materials having adhering face formed by (1) metals, such as aluminum, stainless steel, steel, and zinc steel plate; (2) resins, such as polyimides, acrylate resins, polyurethanes, melamine resins, epoxy resins, and vinyl chlorides; (3) inorganic oxide materials, such as ceramics and glass etc. may be used.
• materials having a coated face as an adhering face may be used.
• a glass transition temperature (Tg 2 ) and a fusing (or melting) point (Tm) of a nonadhesive polymer of each Example and Comparative example were specified from endotherm peak temperature of the obtained chart, by measuring a quantity of heat, using a differential scanning calorimeter (type number) DSC-2CC manufactured by PerkinElmer, Inc., in a temperature range of -60°C to 180°C, at temperature rising velocity for 10°C/minute.
• TM polycaprolactone having a carboxyl group
• a cross-linking agent 0.2 mass parts iso-phthaloyl-bis(2 -methyl aziridine) was added to the obtained mixed solution 100 mass parts and stirred, and the adhesive composition solution was obtained. Obtained adhesive composition solution was transparent.
• the obtained adhesive composition solution was applied using a knife coater, dried under a condition at 90°C and for 5 minutes, and the adhesive layer comprising an adhesive composition having a thickness of 35 ⁇ m was formed on the liner.
• a substrate having a thickness of 80 ⁇ m and comprising ethylene vinyl acetate copolymer modified polyolefin film was dry-laminated onto the adhesive layer to obtain an adhesive sheet having an adhesive layer at one side.
• the low-temperature elongation measured under a condition at -5°C and 300 mm/minute of elastic stress rate showed 200%, and 50% elongation stress measured under a same condition at -5°C showed 21 MPa. Evaluation results of the obtained adhesive sheet are collectively shown in Table 1. (Example 2)
• TM poly carbonate diol
• Example 3 In other conditions, the same method as Example 1 was used, and an adhesive sheet was manufactured. Evaluation results of the obtained adhesive sheet are collectively shown in Table 1. (Example 3)
• Example 4 (may be abbreviate to "NTP3" hereafter)). Except that this polyurethane was used as a nonadhesive polymer (NTP3) solution, an adhesive sheet was manufactured as in Example 1. In addition, a nonvolatile matter concentration of this solution showed 20 mass %. Evaluation results of the obtained adhesive sheet are collectively shown in Table 1. (Example 4)
• Example 1 Example 1 and Example 2, respectively, except having not used the nonadhesive polymer solution. Evaluation results of the obtained adhesive sheet are collectively shown in Table 1.
• a glass transition temperature (Tg 2 ) of the adhesive polymers (NTP1 and NTP2) used in Example 1 and Example 2 was measured from endotherm peak temperature of the obtained chart, by measuring a quantity of heat, using a differential scanning calorimeter (type number) DSC-2CC manufactured by PerkinElmer, Inc., in a temperature range of -60°C to 180°C, at temperature rising velocity for 10°C/minute, and the adhesive polymer (NTP1) used in Example 1 showed -29°C, and the adhesive polymer (NTP2) used in Example 2 showed -36°C.
• the adhesive sheets obtained in each Example, Comparative example, and Reference example were cut by 200 mm x 25 mm, ant the cut sheet was stuck to a melamine baking finish plate by PALTEC Co., Ltd. as an adherend under 20°C environment using a press fitting roller to prepare a test specimen.
• Adhesion of a sheet was performed by a method according to JIS Z0237 8.2.3.
• the releasing strength in a direction of 180 degrees at 300 mm/minute releasing speed was measured using a Tensilon after kept standing for 48 hours under a same temperature after completion of adhesion.
• the adhesive sheets obtained in each Example, Comparative example, and Reference example were cut by 200 mm x 25 mm, ant the cut sheet was stuck to a melamine baking finish plate by PALTEC Co., Ltd. as an adherend under -5°C environment using a press fitting roller to prepare a test specimen.
• Adhesion of a sheet was performed by a method according to JIS Z0237 8.2.3.
• the releasing strength in a direction of 180 degrees at 300 mm/minute releasing speed was measured using a Tensilon after kept standing for 5 minutes under a same temperature after completion of adhesion.
• Rate of tack attenuation ⁇ 1 -[probe tack of composition comprising nonadhesive polymer] ⁇ [probe tack of adhesive polymer itself] ⁇ x 100.
• an adhesive composition which enables to effectively enhance pressure sensitive adhesivity at low temperatures and tack suppression effect at the same time, which makes easy an accurate positioning of the site for sticking, and which can be easily stuck by press fitting even in an environment of low temperature of lower than 0°C and an adhesive sheet constituted with the composition as an adhesive layer.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Adhesive Tapes (AREA)
• Laminated Bodies (AREA)

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  • 2002-08-27 EP EP02759473A patent/EP1423489A1/en not_active Withdrawn
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