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
  • C09J167/00—Adhesives based on polyesters obtained by reactions forming a carboxylic ester 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
  • 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]

Definitions

• One embodiment of the present invention relates to a decorative film.
• Patent Document 1 discloses a decorative sheet made of acrylic resin, and states that when the decorative sheet is attached using a vacuum/compressed air molding method, it is possible to conceal the inclusion of foreign matter such as dust and unevenness on the surface of the substrate.
• One of the objectives of the present invention is to provide a decorative film that can be easily removed immediately after application even if foreign matter is mixed in, is less likely to peel off or float from the substrate over the long term due to increased adhesive strength, and is also highly water resistant.
• a decorative film comprising a substrate and a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a polyester-based resin (A), the ratio (b/a) of the adhesive strength (a) to the adhesive strength (b) of the pressure-sensitive adhesive layer, as measured by the following adhesive strength test, is 1.5 or more;
• the pressure-sensitive adhesive layer has a storage modulus (G') of 1.0 x 10 4 Pa or more and 1.0 x 10 7 Pa or less when measured by a dynamic viscoelasticity test at 23°C and 1 Hz, and
• the pressure-sensitive adhesive layer has a loss tangent (tan ⁇ ) of 0.5 or more and 10.0 or less when measured in a dynamic viscoelasticity test at 23° C.
• Adhesive strength (a): A test piece of 150 mm x 20 mm is cut out from an adhesive sheet for adhesive strength testing, which comprises an adhesive layer having a thickness of 20 ⁇ m and an easily moldable polyethylene terephthalate film having a thickness of 50 ⁇ m on one side of the adhesive layer, and the adhesive layer surface is attached to a polycarbonate plate. The adhesive layer surface is then left for 30 seconds in an environment of 23°C and 50% RH, and the adhesive strength is measured using a tensile tester as a 180-degree peel strength (N/20 mm) at a peel speed of 300 mm/min.
• polyester emulsion is at least one type of emulsion selected from the group consisting of an emulsion in which a polyester resin having a sulfonic acid group is dispersed in an aqueous medium, and an emulsion in which a polyester resin having a carboxyl group is dispersed in an aqueous medium by neutralizing the polyester resin with a basic compound.
• the decorative film according to one embodiment of the present invention can be easily removed immediately after application even if foreign matter is mixed in, and over the long term, the increased adhesive strength makes it less likely to peel or float off the adherend, and it also has excellent water resistance.
• a to B representing a numerical range means A or more and B or less, unless otherwise specified.
• a decorative film according to one embodiment of the present invention is a decorative film including a substrate and a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a polyester resin, the ratio (b/a) of the adhesive strength (a) to the adhesive strength (b) of the pressure-sensitive adhesive layer, as measured by the following adhesive strength test, is 1.5 or more;
• the pressure-sensitive adhesive layer has a storage modulus (G') of 1.0 x 10 4 Pa or more and 1.0 x 10 7 Pa or less when measured by a dynamic viscoelasticity test at 23°C and 1 Hz, and
• the pressure-sensitive adhesive layer has a loss tangent (tan ⁇ ) of 0.5 or more and 10.0 or less when measured in a dynamic viscoelasticity test at 23° C.
• Adhesive strength (a): A test piece of 150 mm x 20 mm is cut out from an adhesive sheet for adhesive strength testing, which comprises an adhesive layer having a thickness of 20 ⁇ m and an easily moldable polyethylene terephthalate film having a thickness of 50 ⁇ m on one side of the adhesive layer, and the adhesive layer surface is attached to a polycarbonate plate. The adhesive layer surface is then left for 30 seconds in an environment of 23°C and 50% RH, and the adhesive strength is measured using a tensile tester as a 180-degree peel strength (N/20 mm) at a peel speed of 300 mm/min.
• the decorative film according to one embodiment of the present invention uses an adhesive layer that has a predetermined adhesive strength to the adherend, so that even if foreign matter is mixed in, the film can be easily removed immediately after application, and over the long term, the increased adhesive strength makes the film less likely to peel off or float from the adherend, resulting in excellent water resistance.
• the adhesive layer has a predetermined viscoelasticity (storage modulus and loss tangent), allowing it to exert an appropriate adhesive strength.
• the substrate plays a role in decoration, but it may also have a decorative layer.
• the decorative film according to one embodiment of the present invention may have a release film on the adhesive layer to protect the adhesive layer until it is used.
• the decorative film according to one embodiment of the present invention has a substrate, which usually constitutes the outermost layer of a decorated formed article obtained by attaching the decorative film to an adherend that is the object of decoration.
• the substrate may be colored or colorless, transparent, translucent or opaque.
• the substrate is preferably in the form of a film or sheet, and may have a single layer structure or may be composed of multiple layers.
• the thickness of the substrate is preferably 10 to 1000 ⁇ m, more preferably 20 to 500 ⁇ m, and further preferably 50 to 300 ⁇ m.
• the substrate may be, for example, a substrate made of a thermoplastic resin.
• the thermoplastic resin is preferably at least one selected from polyvinyl chloride, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, acrylonitrile butadiene styrene (ABS) resin, polyurethane, polyethylene, and polypropylene.
• ABS acrylonitrile butadiene styrene
• polyurethane polyethylene
• polypropylene polypropylene.
• at least one selected from polyvinyl chloride, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, and ABS resin is more preferable, with polyethylene terephthalate being particularly preferable.
• PET polyethylene terephthalate
• PETG amorphous ones called A-PET and PETG, but those with moldability called easily moldable PET are particularly preferable.
• the Young's modulus of the substrate measured in accordance with JIS K 7127 (1999) in a 23°C environment is preferably 40 N/ mm2 or more, more preferably 600 N/ mm2 or more, and even more preferably 900 N/ mm2 or more.
• the Young's modulus is 40 N/mm2 or more , the resulting decorative film is less likely to deform, so that the uneven shape provided on the adhesive layer is less likely to appear on the surface, and problems in appearance are less likely to occur.
• the upper limit of the Young's modulus is preferably 8000 N/ mm2 or less, more preferably 6500 N/ mm2 or less, and even more preferably 3000 N/ mm2 or less. When the Young's modulus is 8000 N/mm2 or less, the decorative film has excellent processability. These upper and lower limits can be combined arbitrarily.
• the substrate may also contain functional substances such as inorganic particles such as silica, plasticizers, colorants, and ultraviolet absorbers depending on the application.
• functional substances such as inorganic particles such as silica, plasticizers, colorants, and ultraviolet absorbers depending on the application.
• patterns, letters, designs, etc. may be printed on the substrate surface to impart design, and patterns, letters, designs, etc. may be formed inside the substrate.
• the decorative film according to one embodiment of the present invention has a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a polyester-based resin (A).
• Adhesive Strength of the Pressure-Sensitive Adhesive Layer to a Polycarbonate Plate The adhesive strength of the pressure-sensitive adhesive layer to a polycarbonate plate can be measured by the following method, the details of which are as described later in the Examples.
• a test piece of 150 mm x 20 mm is cut out from an adhesive sheet for adhesive strength testing, which is made of the adhesive layer having a thickness of 20 ⁇ m and an easily moldable polyethylene terephthalate film having a thickness of 50 ⁇ m on one side of the adhesive layer, and the adhesive layer surface is attached to an adherend of a polycarbonate plate, and the adhesive layer surface is left for 30 seconds under an environment of 23 ° C. and 50% RH.
• the adhesive strength (a) can be obtained by measuring the 180-degree peel strength (N/20 mm) at a peel speed of 300 mm/min using a tensile tester. By changing the time left after attachment to the adherend from the conditions for obtaining the adhesive strength (a), the adhesive strength (b) after 20 minutes can be obtained. Furthermore, the adhesive strength after 24 hours can also be obtained by the same method, and the adhesive strength after 24 hours is hereinafter referred to as the adhesive strength (c).
• the tensile tester for example, an autograph (Shimadzu Corporation's "Autograph AG-X”) can be used.
• the ratio (b/a) of adhesive strength (a) to adhesive strength (b) measured by the method described above is 1.5 or more, preferably 2 to 1000, and more preferably 3 to 100.
• b/a 1.5 or more, the initial adhesive strength of the adhesive layer to the adherend is sufficiently low, so that even if foreign matter is mixed in, the desired decorative film tends to be easily peeled off from the adherend immediately after application.
• the ratio (c/a) of adhesive strength (a) to adhesive strength (c) measured by the method described above is preferably 3.5 or more, more preferably 8 to 1000, and even more preferably 9 to 100.
• c/a is 3.5 or more, peeling or lifting of the decorative film from the adherend due to an increase in adhesive strength over time tends to be less likely to occur, and the desired decorative film tends to be obtained more easily.
• the adhesive strength (a) after 30 seconds of the adhesive layer measured by the above-mentioned method is preferably greater than 0.8 N/20 mm and equal to or less than 7.0 N/20 mm, more preferably equal to or greater than 0.9 N/20 mm and equal to or less than 6.0 N/20 mm, and even more preferably equal to or greater than 0.9 N/20 mm and equal to or less than 5.0 N/20 mm.
• the adhesive strength (a) is within the above range, the initial adhesive strength of the adhesive layer to the adherend is sufficiently low, so that even if foreign matter is mixed in, the decorative film can be easily peeled off immediately after application, and the desired decorative film tends to be obtained.
• the adhesive strength (b) after 20 minutes of the adhesive layer measured by the above-mentioned method is preferably 3.0 N/20 mm or more and 15.0 N/20 mm or less, more preferably 3.5 N/20 mm or more and 14.0 N/20 mm or less, and even more preferably 3.5 N/20 mm or more and 13.0 N/20 mm or less.
• the adhesive strength (c) after 24 hours of the adhesive layer measured by the above-mentioned method is preferably 10.0 N/20 mm or more and 30.0 N/20 mm or less, more preferably 11.0 N/20 mm or more and 20.0 N/20 mm or less, and even more preferably 11.0 N/20 mm or more and 18.0 N/20 mm or less.
• the adhesive strength (c) is within the above range, the decorative film is less likely to peel off or float from the substrate over a long period of time.
• the adhesive strength of the adhesive layer to an acrylonitrile butadiene styrene plate in addition to the adhesive strength to a polycarbonate plate, can be measured using the following method.
• the adhesive strength of the adhesive layer to the acrylonitrile-butadiene-styrene plate can be measured under the same conditions as the method described in the above section "Adhesive strength of the adhesive layer to the polycarbonate plate" except that the adherend is replaced with an acrylonitrile-butadiene-styrene plate, and the details are as described in the examples below.
• the adhesive strengths measured by this method are the adhesive strength after 30 seconds (d), the adhesive strength after 20 minutes (e), and the adhesive strength after 24 hours (f).
• the ratio (e/d) of adhesive strength (d) to adhesive strength (e) measured by the method described above is preferably 1.5 or more, more preferably 2 to 1000, and even more preferably 3 to 100.
• e/d 1.5 or more, the initial adhesive strength of the pressure-sensitive adhesive layer to the adherend is sufficiently low, so that even if foreign matter is mixed in, the desired decorative film tends to be easily peeled off from the adherend immediately after application.
• the preferred range of the ratio (f/d) of adhesive strength (d) to adhesive strength (f) is the same as the preferred range of the ratio (c/a) of adhesive strength (a) to adhesive strength (c) described in the section "Adhesive strength of adhesive layer to polycarbonate plate" above.
• the preferred ranges for adhesive strength (d), adhesive strength (e), and adhesive strength (f) are the same as the preferred ranges for adhesive strength (a), adhesive strength (b), and adhesive strength (c) described above in the section "Adhesive strength of adhesive layer to polycarbonate plate.”
• the pressure-sensitive adhesive sheet includes the pressure-sensitive adhesive layer and a release film provided on one or both sides of the pressure-sensitive adhesive layer. Details of the method for preparing the pressure-sensitive adhesive sheet are as described in the examples below.
• the adhesive sheet for adhesive strength testing according to one embodiment of the present invention comprises the above-mentioned adhesive layer having a thickness of 20 ⁇ m and a 50 ⁇ m easily moldable polyethylene terephthalate film on one side of the adhesive layer.
• the pressure-sensitive adhesive layer has a storage modulus (G') of 1.0 x 10 4 Pa to 1.0 x 10 7 Pa, preferably 5.0 x 10 4 Pa to 5.0 x 10 6 Pa, more preferably 1.0 x 10 5 Pa to 9.5 x 10 5 Pa, when measured by a dynamic viscoelasticity test according to JIS K 7244 at 23°C and 1 Hz. If the storage modulus (G') is within the above range, the initial adhesive strength is sufficiently low, so that even if foreign matter is mixed in, the decorative film tends to be easily peeled off immediately after application.
• the storage modulus (G') can be determined by the method described in the examples below.
• the pressure-sensitive adhesive layer has a loss tangent (tan ⁇ ) of 0.5 to 10.0, preferably 0.7 to 7.0, more preferably 1.0 to 5.0, when measured by a dynamic viscoelasticity test according to JIS K 7244 at 23°C and 0.01 Hz.
• a loss tangent 0.5 to 10.0, preferably 0.7 to 7.0, more preferably 1.0 to 5.0, when measured by a dynamic viscoelasticity test according to JIS K 7244 at 23°C and 0.01 Hz.
• the loss tangent can be determined by the method described in the examples below.
• the thickness of the adhesive layer is preferably 3 to 1000 ⁇ m, and more preferably 5 to 500 ⁇ m.
• the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a polyester-based resin (A) described below.
• the pressure-sensitive adhesive composition is a composition containing the polyester-based resin (A) and other components as necessary.
• polyester resin (A) used in the present invention is obtained by copolymerizing copolymerization components containing polyvalent carboxylic acids (A1) and polyhydric alcohols (A2) as constituent raw materials.
• the polyhydric alcohol (A2) contains at least one of polyether glycol (A2-1) and alkylene glycol (A2-2) from the viewpoint of the balance between the initial adhesive strength and the adhesive strength over time.
• Polycarboxylic acids (A1) used in the present invention include divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids, with divalent carboxylic acids being preferred since they allow the polyester resin to be stably obtained.
• divalent carboxylic acids examples include aliphatic dicarboxylic acids such as malonic acids, dimethylmalonic acids, succinic acids, glutaric acids, adipic acids, trimethyladipic acids, pimelic acids, 2,2-dimethylglutaric acids, azelaic acids, sebacic acids, fumaric acids, maleic acids, itaconic acids, thiodipropionic acids, and diglycolic acids; Aromatic dicarboxylic acids such as terephthalic acids, isophthalic acids, benzylmalonic acids, diphenic acids, 4,4'-oxydibenzoic acids, and naphthalenedicarboxylic acids; Alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acids, 1,2-cyclohexanedicarboxylic acids, 1,3-cyclopentanedicarboxylic acids, 1,4-cyclohexanedicarboxylic acids, 2,5-norbornane
• trivalent or higher carboxylic acids examples include trimellitic acids, pyromellitic acids, adamantanetricarboxylic acids, and trimesic acids. These polyvalent carboxylic acids (A1) can be used alone or in combination of two or more.
• polyvalent carboxylic acids (A1) it is preferable to use aromatic polyvalent carboxylic acids (A1-1) from the viewpoint of imparting cohesive strength, and terephthalic acids and isophthalic acids are particularly preferred.
• the content of such aromatic polycarboxylic acids (A1-1) is preferably 30 mol% or more, more preferably 50 to 90 mol%, and even more preferably 60 to 80 mol%, based on the total content of the polycarboxylic acids (A1).
• the adhesive strength tends to become sufficiently large over time.
• polyvalent carboxylic acids (A1) aliphatic polyvalent carboxylic acids can also be used to impart a tacky feel, such as sebacic acids and azelaic acids.
• the content of such aliphatic polycarboxylic acids is preferably 50 mol % or less, more preferably 40 mol % or less, and even more preferably 30 mol % or less, based on the total content of the polycarboxylic acids (A1).
• the adhesive strength tends to become sufficiently large over time.
• aromatic polycarboxylic acids (A1-1) and aliphatic polycarboxylic acids can be used in combination as the polycarboxylic acids (A1).
• polyester resin (A) In order to increase the number of branching points in the polyester resin (A), it is preferable to use polyvalent carboxylic acids having a valence of three or more, and it is even more preferable to use trimellitic acids, which are relatively less likely to cause gelation.
• the content of such trivalent or higher polyvalent carboxylic acids is preferably 10 mol % or less, and more preferably 0.1 to 5 mol %, based on the total content of the polyvalent carboxylic acids (A1), in order to increase the cohesive strength of the adhesive. If the content is within the above range, gelation tends not to occur during the production of the polyester resin (A).
• the content of polyvalent carboxylic acids (A1) is preferably 5% by mass or more, more preferably 20 to 60% by mass, and even more preferably 30 to 50% by mass, based on the total amount of polyester resin (A). If the content is within the above range, the initial adhesive strength tends to be sufficiently low.
• Polyhydric alcohol (A2) The polyhydric alcohol (A2) used in the present invention includes dihydric alcohols and trihydric or higher polyhydric alcohols.
• dihydric alcohol examples include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 2,2,4-trimethyl-1,6-hexanediol; Alicyclic diols
• trihydric or higher polyhydric alcohol examples include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol.
• polyether glycols (A2-1) such as polytetramethylene ether glycol, polyethylene glycol, and polypropylene glycol.
• the above polyhydric alcohols (A2) can be used alone or in combination of two or more.
• aliphatic diols such as ethylene glycol, diethylene glycol, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol are preferred because they can reduce the initial adhesive strength.
• polyether glycol (A2-1) because it can reduce the initial adhesive strength, and among these, polytetramethylene ether glycol is preferably used.
• the content of polyether glycol (A2-1) in polyhydric alcohol (A2) is preferably 10 to 99 mol % relative to the entire polyhydric alcohol (A2), more preferably 30 to 98 mol %, and even more preferably 51 to 97 mol %. When the content is within the above range, the initial adhesive strength tends to be sufficiently low.
• alkylene glycol (A2-2) examples include aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol (neopentyl glycol), and among these, 1,6-hexanediol, ethylene glycol, and 2,2-dimethyl-1,3-propanediol are preferably used.
• the lower limit of the content of the alkylene glycol (A2-2) is preferably 1 mol% or more, more preferably 10 mol% or more, even more preferably 30 mol% or more, and particularly preferably 70 mol% or more, based on the entire polyhydric alcohol (A2).
• the upper limit of the content of the alkylene glycol (A2-2) is preferably 100 mol% or less, more preferably 95 mol% or less, even more preferably 90 mol% or less, and particularly preferably 85 mol% or less, based on the entire polyhydric alcohol (A2).
• a trihydric or higher polyhydric alcohol in order to increase the number of branching points in the polyester resin (A).
• examples of such trihydric or higher polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol.
• the content of the trihydric or higher polyhydric alcohol is preferably 20 mol% or less, more preferably 0.1 to 10 mol%, and even more preferably 0.5 to 5.0 mol%, based on the total content of the polyhydric alcohol (A2). If the content is within the above range, the polyester resin (A) tends to be easier to manufacture.
• the content of the polyhydric alcohol (A2) is preferably 15% by mass or more, more preferably 40 to 95% by mass, and even more preferably 50 to 80% by mass, based on the total amount of the polyester resin (A). If the content is within the above range, the initial adhesive strength tends to be sufficiently low.
• the blending ratio of polyvalent carboxylic acids (A1) and polyhydric alcohol (A2) is preferably 1 to 3.0 equivalents of polyhydric alcohol (A2) per equivalent of polyvalent carboxylic acids (A1), and particularly preferably 1.1 to 2.0 equivalents.
• the acid value is in a moderate range, which makes it easy to increase the molecular weight and tends to result in a good yield.
• the polyester resin (A) used in the present invention is produced by subjecting the above-mentioned polyvalent carboxylic acids (A1) and polyhydric alcohols (A2) to a polycondensation reaction in the presence of a catalyst by a known method.
• the esterification reaction is carried out first, followed by the polycondensation reaction.
• a catalyst In such an esterification reaction, a catalyst is used, and specific examples include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate, antimony-based catalysts such as antimony trioxide, germanium-based catalysts such as germanium dioxide, and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide, and one or more of these are used. Among these, antimony trioxide, tetrabutyl titanate, germanium dioxide, and zinc acetate are preferred from the perspective of the balance between high catalytic activity and color.
• the amount of the catalyst is preferably 1 to 10,000 ppm, more preferably 10 to 5,000 ppm, and even more preferably 20 to 3,000 ppm, based on the total copolymerization components. If the amount is too small, the polymerization reaction tends not to proceed sufficiently, and if the amount is too large, there is no advantage to shortening the reaction time, and side reactions tend to occur easily.
• the reaction temperature during the esterification reaction is preferably 200 to 300°C, more preferably 210 to 280°C, and even more preferably 220 to 250°C. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur easily. In addition, the pressure during the reaction is usually normal pressure.
• reaction conditions for the polycondensation reaction it is preferable to further compound the same amount of the catalyst as that used in the above esterification reaction, set the reaction temperature to preferably 220 to 280° C., particularly preferably 230 to 270° C., and gradually reduce the pressure of the reaction system to finally react at 5 hPa or less. If the reaction temperature is too low, the reaction tends not to proceed sufficiently, and if it is too high, side reactions such as decomposition tend to occur easily.
• the resin composition ratio of polyester resin (A) (the ratio of structural units derived from each component) can be determined, for example, by NMR.
• the polyester resin (A) is preferably a polyester emulsion.
• emulsion refers to resin particles dispersed in an aqueous medium using an emulsifier or surfactant.
• the polyester resin (A) is preferably a self-emulsifiable resin. If the resin is self-emulsifiable, an emulsion can be formed without using an emulsifier, a surfactant, or the like, and therefore a decorative film having excellent water resistance can be obtained.
• self-emulsifiable means that some hydrophilic group is chemically introduced into the resin skeleton, and the resin itself has emulsifying ability without the need for the addition of an emulsifier or surfactant.
• the polyester emulsion is preferably at least one type of emulsion selected from the group consisting of an emulsion in which a polyester resin having a sulfonic acid group is dispersed in an aqueous medium, and an emulsion in which a polyester resin having a carboxyl group is neutralized with a basic compound and dispersed in an aqueous medium, in order to facilitate the water-solubilization or water-dispersion of the polyester resin.
• Monomers having sulfonic acid groups and/or metal sulfonate salt groups that are used as raw materials for polyester resins having sulfonic acid groups include sulfoisophthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, 5-(sulfopropoxy)isophthalic acid, sulfopropylmalonic acid, sulfosuccinic acid, 2-sulfobenzoic acid, 3-sulfobenzoic acid, 5-sulfosalicylic acid, and methyl esters of these carboxylic acids, as well as alkali metal salts, alkaline earth metal salts, and ammonium salts of these sulfonic acids.
• the amount of the monomer having a sulfonic acid group and/or a sulfonate metal salt group used is preferably 0.1 to 10 mass % and more preferably 2 to 6 mass % based on the total amount of the polyester resin (A).
• Monomers having a carboxylic acid group and/or a metal carboxylate group that are used as raw materials for polyester resins having a carboxyl group include the polycarboxylic acids listed in the "Polycarboxylic acids (A1)" column above, as well as their alkali metal salts, alkaline earth metal salts, and ammonium salts.
• the amount of the monomer having a carboxylic acid group and/or a carboxylic acid metal salt group used is preferably 0.1 to 10 mass % and more preferably 2 to 6 mass % based on the total amount of the polyester resin (A).
• the basic compound used to neutralize the polyester resin having a carboxyl group is not particularly limited, but examples include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic amines such as trimethylamine, dimethylaminoethanol, 2-methyl-2-amino-1-propanol, triethylamine, and ammonia.
• organic amine compounds are preferred, and it is particularly preferred to use tertiary amines such as triethylamine, tributylamine, dimethylethanolamine, and diethylenetriamine.
• the glass transition temperature of the polyester resin (A) is preferably ⁇ 100 to 40° C., more preferably ⁇ 80 to 20° C. or less, and even more preferably ⁇ 70 to 5° C. or less, from the viewpoint of adhesive properties, etc. When the glass transition temperature is within the above range, the polyester resin has excellent stability and water dispersibility.
• the glass transition temperature (Tg) of the polyester resin (A) is a value measured in accordance with JIS K 7121, and specifically, can be measured by the method described in the examples.
• the number average molecular weight (Mn) of the polyester resin (A) is preferably 1,000 to 100,000, more preferably 2,000 to 80,000, and even more preferably 4,000 to 50,000. If the number average molecular weight is within the above range, the polyester resin has excellent solubility and dispersibility in water.
• the weight average molecular weight (Mw) of the polyester resin (A) is preferably 8,000 to 200,000, more preferably 10,000 to 180,000, and even more preferably 20,000 to 150,000. If the weight average molecular weight is within the above range, the polyester resin has excellent solubility and dispersibility in water.
• the number average molecular weight and weight average molecular weight of the polyester resin (A) are values calculated using standard polystyrene molecular weights as measured by gel permeation chromatography (GPC), and can be measured by the method described in the examples.
• the hydroxyl value of the polyester resin (A) is preferably 1 to 50 mgKOH/g, more preferably 2 to 30 mgKOH/g, even more preferably 3 to 20 mgKOH/g, and particularly preferably 4 to 15 mgKOH/g. If the hydroxyl value is within the above range, the crosslinking efficiency with the curing agent (B), which will be described later, tends to be good.
• the acid value of the polyester resin (A) is preferably 10 mgKOH/g or less, more preferably 5 mgKOH/g or less, and even more preferably 3 mgKOH/g or less. If the acid value is within the above range, hydrolysis is less likely to proceed, and the adhesive tends to have good wet heat durability, adhesive strength, and wet heat whitening resistance, and also tends not to corrode the metal even when a metal layer or the like is laminated to one side of the adhesive layer.
• the hydroxyl value and acid value of the polyester resin (A) are determined by neutralization titration based on JIS K 0070-1992.
• the pressure-sensitive adhesive composition may contain a curing agent (B) in addition to the above-mentioned polyester resin (A).
• the curing agent (B) is not particularly limited as long as it is a component capable of undergoing a crosslinking reaction with the polyester resin (A).
• Examples of the curing agent (B) include epoxy curing agents, metal chelate curing agents, and isocyanate curing agents.
• the curing agent (B) may be used alone or in combination of two or more.
• the content of the curing agent (B) is preferably less than 4 parts by mass, more preferably 0.01 to 3 parts by mass, and even more preferably 0.5 parts by mass or less, relative to 100 parts by mass of the polyester resin (A).
• a decorative film can be obtained in which the pressure-sensitive adhesive layer has the desired viscoelasticity (storage modulus and loss tangent) and exhibits suitable adhesive strength.
• a decorative film can be obtained in which a crosslinked structure is sufficiently and appropriately formed, which has high cohesive strength, excellent balance of adhesive properties, and excellent durability.
• epoxy curing agents include epoxy compounds having two or more epoxy groups in one molecule, and specific examples thereof include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidyl isocyanurate, m-N,N-diglycidylaminophenyl glycidyl ether, N,N-diglycidyl toluidine, and N,N-diglycidylaniline.
• the number of epoxy groups in one molecule of the epoxy compound is, for example, 2 to 10.
• Metal chelate hardener examples include compounds in which components such as alkoxide, acetylacetone, and ethyl acetoacetate are coordinated with polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium.
• aluminum chelate compounds are preferred. Specific examples include aluminum isopropylate, aluminum secondary butylate, aluminum ethyl acetoacetate diisopropylate, aluminum trisethyl acetoacetate, and aluminum trisacetylacetonate.
• the metal chelate curing agents can be used alone or in combination.
• the isocyanate-based curing agent may, for example, be an isocyanate compound having two or more isocyanate groups in one molecule.
• diisocyanate compounds having two isocyanate groups in one molecule include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates.
• isocyanate compounds having three or more isocyanate groups in one molecule include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
• isocyanate compounds include multimers (e.g., dimers or trimers, biuret bodies, isocyanurates), derivatives (e.g., addition reaction products of polyhydric alcohols and two or more molecules of diisocyanate compounds), and polymers of the above isocyanate compounds having two or more isocyanate groups.
• the isocyanate-based curing agent may be used alone or in combination of two or more.
• the pressure-sensitive adhesive composition may contain a plasticizer (C) in addition to the above-mentioned polyester resin (A).
• plasticizer (C) examples include alkyl esters of aromatic polycarboxylic acids and alkyl esters of aliphatic polycarboxylic acids, with alkyl esters of aromatic polycarboxylic acids being preferred.
• the plasticizer (C) may be used alone or in combination of two or more.
• the content of the plasticizer (C) is preferably 2 to 40 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 4 to 25 parts by mass, relative to 100 parts by mass of the polyester resin (A). If the content is too high, the adhesive strength tends to decrease due to bleeding out of the plasticizer, whereas if the content is too low, the adhesive strength tends to decrease due to a decrease in compatibility.
• the additive pressure-sensitive adhesive composition may contain at least one selected from the group consisting of resin components other than the polyester resin (A), antistatic agents, silane coupling agents, ultraviolet absorbers, antioxidants, defoamers, fillers, stabilizers, softeners, tackifiers, and wettability adjusters, within the scope of the invention.
• the pressure-sensitive adhesive composition preferably contains an organic solvent in order to adjust its coatability.
• organic solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; esters such as
• the organic solvent may be used alone or in combination.
• the content of the organic solvent is preferably 0 to 90% by mass, and more preferably 10 to 80% by mass.
• the pressure-sensitive adhesive composition can be produced by mixing the above-mentioned components sequentially or simultaneously by a known method. That is, the adhesive composition can be prepared by mixing the polyester resin (A) with other components such as a curing agent (B), a plasticizer (C), an additive, an organic solvent, etc., as necessary, by a conventionally known method. In one embodiment, for example, a polymer solution containing the polymer and an organic solvent obtained when synthesizing the polyester resin (A) is mixed with a curing agent (B), a plasticizer (C), an additive, etc., as necessary.
• the decorative film according to one embodiment of the present invention may have a release film on the adhesive layer as necessary.
• the release film protects the surface of the adhesive layer until the decorative film is actually used, and is peeled off and removed when the decorative film is used.
• the release film is not particularly limited as long as it is a film that can be easily peeled off from the adhesive layer, and examples thereof include resin films, specifically, films of polyesters such as polyethylene terephthalate and polybutylene terephthalate; and films of polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.
• At least one side of the release film may be treated to be easily peeled off with a release treatment agent such as a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based agent.
• the thickness of the release film is preferably 10 to 500 ⁇ m, and more preferably 25 to 200 ⁇ m.
• the decorative film according to one embodiment of the present invention may further include a decorative layer between the substrate and the adhesive layer or on the substrate.
• the decorative layer is a layer provided to impart design to the decorative film, and is a layer that expresses patterns, letters, pictures, and the like.
• any method that can form a decorative film having a substrate and a pressure-sensitive adhesive layer can be adopted without any particular limitation.
• the method of forming a pressure-sensitive adhesive layer by applying and drying a pressure-sensitive adhesive composition on a substrate the method of further laminating a release film on the pressure-sensitive adhesive layer of the decorative film obtained by the method as necessary; the method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition on a release film and drying it, laminating the exposed surface of the obtained pressure-sensitive adhesive layer that is not in contact with the release film and the substrate, and curing to form the layer;
• the adhesive layer can be obtained by applying the above-mentioned adhesive composition onto a substrate or a release film and drying it. Drying conditions vary depending on the type of organic solvent contained in the composition and the thickness of the adhesive layer, but typically the drying temperature is 50 to 150°C and the drying time is 1 to 10 minutes.
• Methods for applying the adhesive composition include, for example, spin coating, knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating.
• the curing conditions are, for example, as follows: Curing is preferably performed for one day or more, more preferably for 2 to 10 days, in an environment of preferably 5 to 60°C, more preferably 15 to 50°C, and preferably 30 to 70% RH, more preferably 40 to 70% RH.
• a crosslinked body consisting of the polyester resin (A) and the curing agent (B) can be efficiently formed.
• a decorated molded article having a decorative film according to one embodiment of the present invention is obtained by attaching the decorative film according to one embodiment of the present invention to at least a part of the surface of a molded article, which is an adherend.
• the substrate for the decorative film may be a molded article having a three-dimensional shape, preferably an article having a three-dimensional curved surface.
• Specific examples include vehicle bodies, vehicle interior materials, building materials, and decorative panels.
• Examples of "vehicles” include four-wheeled vehicles such as passenger cars, buses, and trucks; two-wheeled vehicles such as motorcycles, scooters, and mopeds; and trains.
• the material forming the adherend is not particularly limited, and examples include metal materials; wood; and plastics such as ABS resin, polycarbonate resin, polyester resin, polypropylene resin, and polyethylene resin, the surface of which may be coated with paint.
• Methods for attaching the decorative film to the molded body that is the adherend include, for example, manual attachment, vacuum forming, pressure forming, vacuum pressure forming, and hot high pressure forming. Of these, vacuum pressure forming is preferred.
• the decorated molded body has a molded body (the adherend described above) and a substrate with an adhesive layer formed by removing the release film from the decorative film, which is placed on the surface of the molded body. More specifically, the decorated molded body has a molded body, an adhesive layer, a decorative layer if necessary, and a substrate in this order.
• Measurement device HLC-8220GPC (manufactured by Tosoh) GPC column configuration: The following five columns (all manufactured by Tosoh) (1) TSK-GELHXL-H (guard column) (2) TSK-GELG7000HXL (3)TSK-GELGMHXL (4) TSK-GELGMHXL (5) TSK-GELG2500HXL Sample concentration: diluted with tetrahydrofuran to 1.0 mg/cm 3 Mobile phase solvent: tetrahydrofuran Flow rate: 1.0 cm 3 /min Column temperature: 40° C.
• Glass transition temperature (Tg) The measurement was performed in accordance with JIS K 7121 using a differential scanning calorimeter (manufactured by TA Instruments Japan, product name "DSC Q2000") at a temperature rise rate of 20°C/min.
• polyester resin constituting the pressure-sensitive adhesive layer As the polyester resin constituting the pressure-sensitive adhesive layer, commercially available products and synthetic products shown in the following Table 1 were used. Table 1 shows the physical properties of each polyester resin.
• Polyester A Polyester resin (A-1) described in [0134] of JP-A-2022-153321
• Polyester B Polyester resin (A-3) described in [0129] of JP-A-2022-111238
• Pressure-sensitive adhesive compositions were prepared in the following formulations 1-10, and the formulation ratios are shown in Table 2. The forms of the obtained compositions are shown separately as emulsions and solvent-based compositions.
• Blend 1 25 parts by mass of diethyl phthalate (DEP) as a plasticizer and 2 parts by mass of aluminum chelating hardener "M-12AT (Soken Chemical Industries, Ltd.)" were added to polyester resin "Vylonal MD-1480 (Toyobo Co., Ltd.)” (solid content concentration 25%, 100 parts by mass as solid content), and the mixture was stirred and mixed to obtain adhesive composition (I).
• adhesive composition (II) was obtained by the same method as Blend 1, except that the aluminum chelating hardener was not added.
• Blend 6 a pressure-sensitive adhesive composition (VI) was obtained by adding each component in the blending amount shown in Table 2 to Polyester A (solid content concentration 50%, 100 parts by mass as solid content) shown in Table 1.
• Blend 7 a pressure-sensitive adhesive composition (VII) was obtained in the same manner as Blend 6, except that Polyester B shown in Table 1 was used.
• Blend 8 the acrylic resin "E03H (manufactured by Soken Chemical Engineering Co., Ltd.)" (100 parts by mass as solid content) was used to obtain a pressure-sensitive adhesive composition (VIII).
• Blends 9 and 10 the acrylic resins "1604N (manufactured by Soken Chemical Engineering Co., Ltd.)” and “2094 (manufactured by Soken Chemical Engineering Co., Ltd.)” were used, respectively, and each component was added to each acrylic resin (100 parts by mass as solid content) in the blending amount shown in Table 2 to obtain pressure-sensitive adhesive compositions (IX) and (X).
• Example 1 ⁇ Preparation of decorative film>
• the degassed pressure-sensitive adhesive composition (I) was applied onto a release-treated polyethylene terephthalate film (release film) using a doctor blade, and dried at 80° C. for 5 minutes to obtain a sheet having a coating film with a dry thickness of 20 ⁇ m.
• a 50 ⁇ m-thick easily moldable polyethylene terephthalate (PET) film "FT50" manufactured by Teijin was attached to the coating surface of the sheet, and left to stand for 24 hours under conditions of 23° C./50% RH for aging, to obtain a decorative film having a release film, a 20 ⁇ m-thick pressure-sensitive adhesive layer, and an easily moldable PET film.
• the physical properties of the decorative film were evaluated as follows. The evaluation results are shown in Table 3.
• the adhesive layer used for evaluating viscoelasticity was prepared by the following procedure. First, a 25 ⁇ m thick adhesive layer formed on a release film was laminated with another 25 ⁇ m thick adhesive layer on a release film under a 23° C./50% RH environment, and treated in an autoclave at 50° C./5 atm for 20 minutes to obtain a 50 ⁇ m thick adhesive layer. The operation of peeling off one release film and laminating a 25 ⁇ m thick adhesive layer on another release film was repeated in the same manner to prepare a viscoelastic sample with a total thickness of 1.0 mm.
• the degassed pressure-sensitive adhesive composition (I) was applied onto a 50 ⁇ m thick easily moldable polyethylene terephthalate (PET) film using a doctor blade, and dried at 80° C. for 3 minutes to form a pressure-sensitive adhesive layer with a dry thickness of 20 ⁇ m, to prepare a pressure-sensitive adhesive sheet for adhesive strength testing.
• PET easily moldable polyethylene terephthalate
• a test piece of 150 mm ⁇ 20 mm was cut out from the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer surface was attached to a polycarbonate plate adherend, and the sheet was left for 30 seconds under a 23° C., 50% RH environment, and then the adhesive strength (a) was determined by measuring the 180° peel strength (N/20 mm) at a peel speed of 300 mm/min using an autograph.
• the adhesive strength (b) after 20 minutes and the adhesive strength (c) after 24 hours were also determined under the same conditions as those for determining the adhesive strength (a), except that the time left after attachment to the adherend was changed.
• An autograph (Shimadzu Corporation's "Autograph AG-X”) was used to measure the adhesive strength.
• Examples 2 to 5, Comparative Examples 1 to 5 The decorative films of Examples 2 to 5 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1, except that the adhesive compositions (II) to (V) and adhesive compositions (VI) to (X) prepared according to the above-mentioned formulations 2 to 5 and formulations 6 to 10 were used instead of the adhesive composition (I).
• the physical properties of each decorative film were evaluated under the same conditions as those described in the column of ⁇ Evaluation of physical properties> in Example 1. The evaluation results are shown in Table 3.
• Acrylic resin E03H (manufactured by Soken Chemical Industries, Ltd.) 1604N (manufactured by Soken Chemical Industries, Ltd.) 2094 (manufactured by Soken Chemical Industries, Ltd.)
• Hardener M-12AT Aluminum chelate hardener (manufactured by Soken Chemical Industries, Ltd.)
• L-45 Isocyanate-based hardener (manufactured by Soken Chemical Industries, Ltd.)
• E-AX Epoxy hardener (manufactured by Soken Chemical Industries, Ltd.)

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