TW202409138A - Copolymerized polyester, sheet-like adhesive, multilayer film and molded body - Google Patents

Abstract

The present invention addresses the problem of providing a copolymerized polyester which is suitable for use as an adhesive that has excellent handling properties and low environmental load, while being suitable for use in thermal three-dimensional molding. The present invention relates to a copolymerized polyester which has an aromatic group concentration in the copolymerized polyester of 5% by mass to 25% by mass, a glass transition temperature of -80 DEG C to 10 DEG C, and a melting point of 70 DEG C to 130 DEG C.

Description

Copolyester, sheet adhesives, laminated films and molded articles

The present invention relates to copolyesters. More specifically, it relates to copolyesters, sheet adhesives containing the copolyesters, and laminated films and molded products using the sheet adhesives.

In the past, in various fields such as home appliances, automobile interiors, and miscellaneous goods, white, black, and colored inks were used to decorate characters and patterns on the surface of the molded body as the adherend. , to demonstrate high functionality and design. In particular, in the decoration of molded objects with complex surface shapes such as three-dimensional curved surfaces, decorative pieces in which decorative sheets are laminated on the surface of articles with three-dimensional curved surfaces are used in various applications. As a method of decorating a laminated decorative sheet, it is known that the decorative sheet disclosed in Patent Document 1 is introduced into a molding device, the decorative sheet is softened by heating, and the softened decorative sheet is attached to the surface of a three-dimensional molded body. , a method of vacuum/pressure forming (TOM forming) for decoration, etc.

Decorative sheets used for TOM molding are known to have a decorative layer (surface layer or surface protective layer), an adhesive layer, and the like. When using a decorative sheet with a decorative layer and an adhesive layer, the adhesive force of the adhesive layer is used to bond the decorative sheet to the molded body. Patent Document 2 discloses a molding laminate having a silicone adhesive layer and an acrylic adhesive layer as a decorative molding laminate suitable for TOM molding. [Prior Technical Document] 〔Patent documents〕

[Patent Document 1] Japanese Patent Application Publication No. 2002-067137 [Patent Document 2] Japanese Patent Application Publication No. 2017-154410

[Problem to be solved by the invention]

Adhesives that exhibit tackiness at room temperature have a problem with poor handling properties when peeling off the release film. For example, when the adhesive layers are in contact with each other, it may be difficult to peel them off. Even if they can be peeled off, the surface of the adhesive layer may be uneven, and the appearance of the film may deteriorate during molding. Therefore, it is difficult to mass-produce decorative molded products using a TOM molding machine or the like. In addition, when applying an adhesive layer to a decorative film, a solvent or the like must be used to apply the adhesive and dry it, causing an environmental load. Furthermore, in three-dimensional thermoforming represented by TOM molding, from the viewpoint of improving work efficiency, adhesives that can be bonded by heating in a short time are required. An object of the present invention is to provide an ideal copolymer polyester that is excellent in handleability, has low environmental load, and is suitable as an adhesive for three-dimensional thermoforming. [Methods to solve problems]

As a result of careful research to solve this problem, the inventors of the present invention discovered that a copolyester having the following characteristics can form a sheet-like adhesive that has good handling properties and good adhesion during three-dimensional thermoforming of decorative films, and completed the present invention. That is, the present invention has the following configuration.

[1] A copolymerized polyester, the aromatic group concentration in the aforementioned copolymerized polyester is 5 to 25% by mass, Glass transition temperature is -80~10℃, The melting point is 70~130℃. [2] The copolymer polyester as described in [1] above, wherein the crystallization heat of fusion is 0.5 J/g or more and 20 J/g or less. [3] The copolymer polyester as described in [1] or [2] above, wherein the elongation at break measured at 25°C is 500% or more. [4] The copolymer polyester according to any one of [1] to [3] above, wherein the storage elastic modulus at 0° C. is 150 MPa or less. [5] The copolymer polyester as described in any one of [1] to [4] above, wherein the tensile elastic modulus measured at 25°C is 10 to 80 MPa. [6] A sheet-like adhesive is composed of copolyester as described in any one of the aforementioned [1] to [5]. [7] The sheet adhesive described in the aforementioned [6] is used for three-dimensional thermoforming. [8] A laminated film is obtained by laminating the sheet-like adhesive described in [6] above. [9] A molded body obtained by laminating the sheet-like adhesive described in [6] above. [Effects of the invention]

The copolyester of the present invention has excellent handleability, good adhesion during three-dimensional thermoforming, and can be adhered to the base material even with a small amount of heat, so it has low environmental load. Therefore, it is suitable as an adhesive for three-dimensional thermoforming and can also be used as a sheet adhesive using it.

Hereinafter, one embodiment of the present invention will be described in detail. However, the present invention is not limited to this, and can be implemented with various modifications within the scope described above.

<Copolyester> The copolyester of the present invention contains structural units having aromatic groups, and the aromatic group concentration in the copolyester is 5 to 25% by mass. The aromatic group concentration is preferably 7% by mass or more, more preferably 9% by mass or more, and further preferably 11% by mass or more, and preferably 22% by mass or less, more preferably 20% by mass or less, and further preferably 18% by mass or less. By keeping the aromatic group concentration within the above range, the shrinkage stress after molding is suppressed, and the copolyester can have good adhesion. The aromatic group concentration here refers to the mass ratio of the aromatic ring excluding the substituent in the copolyester. For example, polyethylene terephthalate contains one benzene ring relative to the molecular weight of the ethylene terephthalate unit of 192.2 (62.1 (molecular weight of ethylene glycol) + 166.1 (molecular weight of terephthalic acid) - 18 × 2), so the aromatic group concentration is 40.6% by mass based on the molecular weight of benzene of 78.1. In addition, in a polyester composed of two or more polycarboxylic acid components and/or two or more polyol components, for example, in the case of a1 shown in the embodiment (terephthalic acid: 50 mol%, adipic acid: 50 mol%, 1,4-butanediol: 100 mol%), the molecular weight of 1 mol structural unit is calculated to be 166.1 × 0.5 + 146.1 × 0.5 + 90.1 × 1 - 18 × 2 = 210.2. In addition, the molecular weight of the aromatic group in 1 mol structural unit is calculated to be 78.1×0.5=39.1. Therefore, the aromatic group concentration of a1 is 39.1/210.2, which is about 19 mass % (18.6 mass %). In addition, when the copolyester contains a high molecular weight component such as polytetramethylene glycol described later in the structural unit, the number average molecular weight can also be used as the molecular weight for calculation.

The structural unit with an aromatic group constituting the copolyester in the present invention refers to the polycarboxylic acid component, the polyol component, or both of them having an aromatic group constituting the copolyester. The number of aromatic groups contained in the aforementioned polycarboxylic acid component or the aforementioned polyol component is not particularly limited, but preferably 1 to 2. As for the aforementioned aromatic group, it is preferably an aromatic hydrocarbon with 6 to 12 carbon atoms, for example, benzene, naphthalene, etc. Moreover, the structural unit with an aromatic group constituting the copolyester of the present invention is not particularly limited, and examples thereof include: structural units derived from aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, phthalic acid, and trimellitic acid, structural units derived from aromatic polyols such as bisphenol A ethylene oxide adducts and bisphenol A propylene oxide adducts, etc. The aromatic structural unit constituting the copolyester is preferably a structural unit derived from an aromatic polycarboxylic acid, more preferably contains terephthalic acid, and contains at least one selected from isophthalic acid, naphthalene dicarboxylic acid, phthalic acid and trimellitic acid.

The copolyester of the present invention preferably has a crystal melting heat of 20 J/g or less. More preferably, it is 15 J/g or less. Also, it is preferably 0.5 J/g or more, more preferably 1 J/g or more, and further preferably 4 J/g or more. By having a crystal melting heat within the aforementioned range, in three-dimensional thermoforming such as TOM forming, it still shows good adhesion to the substrate even when forming must be performed at a low temperature and in a short time. Also, from the perspective of heat resistance, a higher crystal melting heat is better. On the other hand, from the perspective of TOM formability, a lower crystal melting heat is better. In order to adjust the crystal melting heat to the aforementioned range, for example, the copolyester can be adjusted by having terephthalic acid and combining ortho-substituted aromatic dicarboxylic acids such as phthalic acid, meta-substituted aromatic dicarboxylic acids such as isophthalic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, dimer acid, sebacic acid, adipic acid and other aliphatic dicarboxylic acids as polycarboxylic acids constituting the copolyester. Among them, it is preferred to use terephthalic acid in combination with one or more selected from the group consisting of meta-substituted aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and aliphatic dicarboxylic acids, and it is more preferred to use terephthalic acid in combination with alicyclic dicarboxylic acids. In particular, by combining alicyclic dicarboxylic acids, it is possible to suppress the melting point or crystal melting heat from rising excessively, making it easier to adjust these to the desired range.

As the polyol component constituting the copolyester (but excluding the polyol component having an aromatic group), there may be mentioned: aliphatic diols such as ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, diethylene glycol, 2,2-dimethyl-1,3-propanediol, 1,4-pentanediol, 1,5-pentanediol, 1,3-pentanediol, 3-methyl-1,5-pentanediol, triethylene glycol, 1,6-hexanediol, 1,8-octanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecanediol; and linear polyalkylene glycols such as diethylene glycol, polyethylene glycol, and polytetramethylene glycol. These can be used alone or in combination of two or more. Among them, ethylene glycol, diethylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6-hexanediol and polytetramethylene glycol are preferred.

The copolymer polyester of the present invention has a glass transition temperature of -80~10°C. More preferably, it is -70~0℃, and further more preferably, it is -65~-10℃. If the glass transition temperature exceeds the aforementioned upper limit, the film may peel off due to shrinkage stress after molding. Moreover, if it is lower than the said lower limit value, anti-blocking property may fall and handleability may become poor. In addition, the glass transition temperature is a value measured by the method described in the Example.

The copolymer polyester of the present invention has a melting point of 70 to 130°C. More preferably, it is 80°C or higher, still more preferably, it is 90°C or higher, still further preferably, it is 100°C or higher. Furthermore, the temperature is preferably 125°C or lower, and further preferably 120°C or lower. If the copolymer polyester does not have a melting point or the melting point does not reach the aforementioned lower limit, the anti-blocking property will be reduced and the handleability will be poor. Moreover, if it exceeds the said upper limit, adhesiveness will become unsatisfactory, and low-temperature formability will be inferior. In addition, from the viewpoint of heat resistance, the one with a higher melting point is preferable. On the other hand, from the viewpoint of TOM formability, the one with the lower melting point is better. In addition, the melting point is a value measured by the method described in the Examples.

The copolyester of the present invention preferably has an elongation at break measured at 25°C of 500% or more, more preferably 600% or more, and even more preferably 700% or more. When the elongation at break measured at 25°C is above the above value, the portion to be stretched during three-dimensional thermoforming can still follow the elongation of the substrate and can be well bonded to the substrate. The upper limit of the elongation at break measured at 25°C is not particularly limited, but is usually 1000% or less. In order to improve the elongation at break of the copolyester, it is preferred to have a long-chain aliphatic monomer without a substituent (for example, having a total of 5 or more hydroxyl groups and/or ether groups continuously between reactive groups) as a structural unit of the copolyester. Examples of such aliphatic monomers include linear aliphatic dicarboxylic acids such as adipic acid and sebacic acid, linear aliphatic diols such as 1,6-hexanediol and 1,8-octanediol, and linear polyalkylene glycols such as diethylene glycol, polyethylene glycol, and polytetramethylene glycol. The elongation at break can be measured by the measurement method described in the examples.

The copolymerized polyester of the present invention preferably has a storage elastic modulus at 0° C. of 150 MPa or less, more preferably 120 MPa or less, and further preferably 100 MPa or less. If the storage elastic modulus at 0° C. exceeds the above value, poor appearance or reduced adhesion may occur during three-dimensional thermoforming. The lower limit of the storage elastic modulus at 0° C. is not particularly limited, but is usually 1 MPa or more, preferably 10 MPa or more. In order to set the 0° C. storage elastic modulus of the copolyester within the aforementioned range, for example, it is preferable to use an aliphatic monomer having a long chain (for example, a total of more than 5 hydrocarbon groups and/or ether groups continuously between reactive groups). As a structural unit of copolymerized polyester, examples of such aliphatic monomers include: aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and dimer acid, 1,6-hexanediol, 1 , 8-octanediol, 3-methyl-1,5-pentanediol, dimer diol and other aliphatic diols, diethylene glycol, polyethylene glycol, polytetramethylene glycol and other polymers Alkylene glycol, etc.

The copolymer polyester of the present invention preferably has a tensile elastic modulus measured at 25°C of 10 to 80 MPa. If the tensile elastic modulus measured at 25°C is within the above range, the formability will be good in three-dimensional thermoforming at 120°C. In order to make the tensile elastic modulus measured at 25° C. fall within the above range as a copolymerized polyester, for example, the copolymerized polyester can contain terephthalic acid and an ortho-substituted aromatic dicarboxylic acid such as phthalic acid, Meta-substituted aromatic dicarboxylic acids such as isophthalic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, dimer acids, sebacic acid, adipic acid and other aliphatic dicarboxylic acids, etc. Adjusted as polycarboxylic acid constituting copolyester. Among them, a combination of terephthalic acid and one or more selected from the group consisting of meta-substituted aromatic dicarboxylic acid, alicyclic dicarboxylic acid, and aliphatic dicarboxylic acid is preferred. Terephthalic acid and alicyclic dicarboxylic acid are used in combination.

The peak temperature of the dielectric loss tangent (tanδ) of the copolyester of the present invention measured by a dynamic viscoelasticity measuring device is preferably 40°C or less, more preferably 15°C or less, and further preferably 0°C or less. If tanδ exceeds the above value, there may be a case where the appearance is poor or the adhesiveness is reduced during three-dimensional thermoforming. The lower limit of the peak temperature of the dielectric loss tangent (tanδ) is not particularly limited, but is usually -70°C or more. In order to make the peak temperature of the dielectric loss tangent (tanδ) within the above-mentioned range, for example, it is preferred to have a long-chain (for example, a total of more than 5 hydroxyl groups and/or ether groups are continuously present between the reactive groups) aliphatic monomers as the structural units of the copolyester. Examples of such aliphatic monomers include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and dimer acid, aliphatic diols such as 1,6-hexanediol, 1,8-octanediol, 3-methyl-1,5-pentanediol, and dimer glycol, and polyalkylene glycols such as diethylene glycol, polyethylene glycol, and polytetramethylene glycol.

The reduced viscosity of the copolyester of the present invention is preferably 0.5 dl/g or more. More preferably, it is 0.7 dl/g or more, and further preferably, it is 0.9 dl/g or more. When the reduced viscosity is above the above value, the elongation at break of the copolyester is increased, and as a result, it can follow the elongation of the substrate during three-dimensional thermoforming, and the adhesion is improved. In addition, it is preferably less than 2.5 dl/g, more preferably less than 2.0 dl/g, further preferably less than 1.7 dl/g, and further preferably less than 1.3 dl/g. If it exceeds 2.5 dl/g, there is a possibility that the wettability to the adherend becomes insufficient.

<Sheet adhesive> The sheet adhesive of the present invention contains the aforementioned copolyester and has excellent handling and adhesion properties, and can be used as an adhesive for three-dimensional thermoforming.

In addition to the aforementioned copolymerized polyester, various other additives can also be blended into the sheet adhesive of the present invention. As for additives, resins other than the copolyester of the present invention, antioxidants, inorganic fillers, stabilizers, ultraviolet absorbers, anti-aging agents, etc. can be added as long as they do not impair the characteristics of the present invention. It is widely used as an additive.

＜Antioxidants＞ When the sheet adhesive of the present invention requires high temperature and long-term durability, it is preferred to add an antioxidant. For example, as a hindered phenol system, 1,3,5-trimeric isocyanate (3,5-di(tertiary butyl)-4-hydroxybenzyl) ester, 1,1,3-triisocyanate (4-hydroxy-2-methyl-5-tertiary butylphenyl)butane, 1,1-bis(3-tertiary butyl-6-methyl-4-hydroxyphenyl)butane, 3 ,5-bis(1,1-dimethylethyl)-4-hydroxy-phenylpropionic acid, neopentylerythritol 4(3,5-bis(tertiary butyl)-4-hydroxyphenyl)propionic acid Ester, 3-(1,1-dimethylethyl)-4-hydroxy-5-methyl-phenylpropionic acid, 3,9-bis[1,1-dimethyl-2-[(3-tri grade butyl-4-hydroxy-5-methylphenyl)propyloxy]ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-tris Methyl-2,4,6-bis(3',5'-bis(tertiary butyl)-4'-hydroxybenzyl)benzene, etc., and as phosphorus series, 3,9-bis( p-Nonylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 3,9-bis(octadecyloxy)-2, 4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, tris(monononylphenyl)phosphite, triphenoxyphosphine, isodecyl phosphite, Isodecyl phenyl phosphate, diphenyl 2-ethylhexyl phosphite, dinonylphenyl bis(nonylphenyl) phosphate, 1,1,3-shen(2-methyl-4-di (Tridecyl)phosphite-5-tertiary butylphenyl)butane, ginseng (2,4-di(tertiary butyl)phenyl) phosphite, neopentylerythritol bis(2,4 -Di(tertiary butyl)phenyl phosphite), 2,2'-methylene bis(4,6-di(tertiary butyl)phenyl) 2-ethylhexyl phosphite, bis( 2,6-bis(tertiary butyl)-4-methylphenyl)nepententerythritol diphosphite, etc. Examples of thioether systems include: 4,4'-thiobis[2-tertiary Butyl-5-methylphenol]bis[3-(dodecylthio)propionate], thiobis[2-(1,1-dimethylethyl)-5-methyl-4, 1-phenylene]bis[3-(tetradecylthio)-propionate], neopentylerythritol 4(3-n-dodecylthiopropionate), bis(tridedecylthio)-propionate Dipropionate. These can be used individually or in combination. The added amount is preferably not less than 0.1% by mass and not more than 5% by mass based on the solid content of the sheet adhesive. If the content is less than 0.1% by mass, the thermal deterioration resistance effect may be insufficient. If it exceeds 5% by mass, adhesion, etc. may be adversely affected.

As for the resins other than the copolymerized polyester of the present invention, thermoplastic resins such as polyester resins other than the copolymerized polyester of the present invention, epoxy resins, polyolefin resins, styrene resins, and polyurethane resins can be added. As well as phenolic resin, phenoxy resin, petroleum resin, rosin, and modified rosin, etc.

<Epoxy resin> The sheet adhesive of the present invention may also contain an epoxy resin as described above. The epoxy resin used in the present invention is not particularly limited, and examples thereof include: bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, brominated bisphenol A diglycidyl ether and other glycidyl ether types, hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester and other glycidyl ester types, triglycidyl isocyanate, glycidyl hydantoin, tetraglycidyl diaminoglycidyl ether, and the like. Diphenylmethane, triglycidyl p-aminophenol, triglycidyl m-aminophenol, diglycidyl aniline, diglycidyl toluidine, tetraglycidyl m-xylenediamine, diglycidyl tribromoaniline, tetraglycidyl bisaminomethyl cyclohexane and other epoxy amines, or 3,4-epoxyhexyl methyl formate, epoxidized polybutadiene, epoxidized soybean oil and other aliphatic epoxides, etc. The number average molecular weight of the epoxy resin is preferably 450 to 40,000. If it is less than 450, the sheet adhesive is very easy to soften and has poor mechanical properties. If it is more than 40,000, the compatibility with the copolymer polyester becomes extremely poor, and the adhesive effect may be impaired.

When the sheet adhesive of the present invention contains epoxy resin, the content is preferably 10 parts by mass or less relative to 100 parts by mass of the copolyester. When the content is within the above range, the copolyester can be properly plasticized, and the generation of stress at the bonding interface that changes with time can be prevented by limiting the crystallization of the copolyester or inhibiting enthalpy relaxation. In addition, the adhesion to the metal surface can be improved.

<Polyolefin resin> The sheet adhesive of the present invention may also contain a polyolefin resin as described above. The polyolefin resin used in the present invention is not particularly limited, and examples thereof include: ultra-low density polyethylene, linear low density polyethylene, ethylene propylene elastomer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate-maleic anhydride terpolymer, ethylene-ethyl acrylate-maleic anhydride terpolymer, ethylene-methacrylate glycidyl methacrylate copolymer, ethylene-vinyl acetate-methacrylate glycidyl methacrylate terpolymer, ethylene-methyl acrylate-methacrylate glycidyl methacrylate terpolymer, etc.

The blending amount of the polyolefin resin used in the present invention is preferably 15 parts by mass or less relative to 100 parts by mass of the copolyester. By being within the above range, the strain energy caused by crystallization and enthalpy relaxation of the copolyester can be relaxed, and the deterioration of the adhesive strength over time can be suppressed.

＜Inorganic filler＞ As for the inorganic filler, it is preferable to blend 40 parts by mass or less of talc, calcium carbonate, zinc oxide, titanium oxide, clay, bentonite, fumed silica, and silica based on 100 parts by mass of the copolyester. Powder, mica, etc.

In addition, various metal salt nucleating agents, coloring pigments, inorganic and organic fillers, viscosity enhancers, quenchers, metal deactivators, UV absorbers, stabilizers such as HALS, silane coupling agents, flame retardants, etc. can also be added as other additives.

<Laminated film, molded body> The laminated film of the present invention can be obtained by laminating the aforementioned sheet adhesive and a substrate. If a decorative film is used as a substrate, a decorative sheet can be obtained as a laminated film. In addition, the aforementioned sheet adhesive and laminated film can be used to decorate a molded body. When decorating a three-dimensional molded body, for example, the sheet adhesive and the laminated film can be pressed against the surface of the molded body to be adhered, with the adhesive layer facing the surface of the molded body to be adhered, to obtain a decorated molded body. As for the molding method under vacuum conditions or reduced pressure conditions, for example, TOM molding method can be cited. The sheet adhesive and laminated film of the present invention are particularly suitable for use in molding methods such as TOM molding.

As mentioned above, the manufacturing method of the molded body of the present invention is preferably the TOM (Three Dimension Overlay Method). The so-called TOM method, for example, uses a vacuum pump to suck air from two spaces in the device divided by the decorative sheet fixed to the fixed frame, and evacuates the inside of the decoration. At the same time, the decorative sheet is heated to a specified temperature for softening by an infrared heater. At the time when the decorative sheet is heated and softened, the atmosphere is introduced into only one side of the space in the device, so that the decorative sheet is firmly and closely attached to the three-dimensional shape of the molded body that is the adherend in the vacuum environment. If necessary, pressure pressing from the silicone rubber sheet side can also be appropriately used. After the decorative sheet is bonded to the molded body, the silicone rubber sheet is peeled off from the decorative sheet, and then the molded decorative sheet is peeled off from the fixing frame to obtain a decorated molded body. The vacuum forming is usually performed at about 80-150°C, preferably at about 100-140°C.

The molded body obtained by the present invention is not particularly limited, and examples thereof include: bumpers, front spoilers, rear spoilers, side skirts, side trims, rearview mirrors and other automotive exterior parts, instrument panels, center consoles, door switch panels and other automotive interior parts, mobile phones, audio products, refrigerators, heaters, lighting fixtures and other home appliance housings, washstands, etc.

This application claims priority based on Japanese Patent Application No. 2022-106839 filed on July 1, 2022. The entire specification of Japanese Patent Application No. 2022-106839 filed on July 1, 2022 is incorporated into this application by reference. [Example]

In order to further illustrate the present invention in detail, the following examples are given, but the present invention is not limited by the examples. In addition, each measured value recorded in the examples is measured by the following method.

Determination of resin composition: The test sample (copolyester) was dissolved in heavy chloroform and analyzed by 1H-NMR using a nuclear magnetic resonance (NMR) device 400-MR manufactured by Varian. The molar ratio was calculated from the integral value. In addition, the aromatic group concentration (mass %) was calculated from the obtained resin composition results.

Melting point, glass transition temperature, crystallization fusion heat: Using the differential scanning calorimeter "DSC220" manufactured by Seiko Instruments, 5 mg of the test sample (copolyester) was placed in an aluminum pan, covered with a lid and sealed, and kept at 250°C for 5 minutes to completely melt the sample. The liquid was rapidly cooled using nitrogen, and then measured from -150°C to 250°C at a heating rate of 20°C/min. In the endothermic curve obtained in this process, the temperature of the intersection of the baseline before the endothermic peak and the tangent line toward the endothermic peak was set as the glass transition temperature (Tg, unit: °C). In addition, the maximum peak temperature of the fusion heat was set as the melting point (Tm, unit: °C), and the area of the endothermic curve was set as the crystallization fusion heat (ΔH, unit: J/g).

Restored viscosity: Dissolve 0.10g of a fully dried measurement sample (copolyester) in 25 ml of a mixed solvent of phenol/tetrachloroethane (mass ratio 6/4), and measure using an Ubbelohde viscometer at 30°C.

Production of sheet adhesive: Using an extruder with a screw diameter of 40 mmφ, the copolyester is extruded on a release film (38 μm thick) through a T-shaped die at a temperature of 160°C so that the thickness of the adhesive (copolyester layer) becomes 30 μm. On the release-treated PET film), a sheet-like adhesive is obtained.

Production of laminated films: The obtained sheet-like adhesive was molded using a vacuum heating press (HH46 manufactured by TRM Corporation) to form a decorative film (MLE901-80 manufactured by Taxilon CI, polyvinyl chloride) at a temperature of 135°C and a pressure of 20 MPa for 20 seconds. Use vacuum heating and pressure to produce a laminated film with a sheet-like adhesive.

Manufacturing of the formed body: On the lower box of the double-sided vacuum forming device (trade name NGF-T-0203, manufactured by Bushi Vacuum Co., Ltd.) composed of upper and lower boxes, an upper and lower lifting table is provided, and a rectangular fixture with a length of 9 cm, a width of 5 cm, and a height of 5 cm is set on it, and an ABS-made bonded formed body with a length of 9 cm, a width of 5 cm, and a height of 0.2 cm is set. Afterwards, the release film of the obtained laminated film is peeled off on the sheet clamp frame of the upper box of the above-mentioned double-sided vacuum forming device, and the adhesive layer of the laminated film is set in a manner opposite to the bonded formed body of the lower box. Next, the vacuum degree in the upper and lower boxes is reduced to 1.0 kPa, and the temperature of the laminated film is heated to 120°C using a near-infrared heater to raise the bonded molded body, and the bonded molded body and the laminated film are pressed together. After that, only 300 kPa compressed air is introduced into the upper box and maintained for 4 seconds. The upper and lower boxes are released to atmospheric pressure to obtain a molded body with the laminated film vacuum pressed together.

Tensile modulus: The release film was peeled off from the sheet adhesive obtained as described above, and a tensile test was performed at a tensile speed of 100 mm/min at 25°C using Shimadzu Autograph AG-XPlus to obtain a stress-strain curve. The tensile modulus was calculated from the slope of the obtained stress-strain curve in the range of tensile load 0.1~1.5N.

Elongation at break: The release film was peeled off from the sheet adhesive obtained as described above, and a tensile test was performed using Shimadzu Autograph AG-XPlus at a tensile speed of 100 mm/min at 25°C to measure the elongation at break.

Determination of storage elastic modulus and dielectric loss tangent (tanδ): From the sheet adhesive obtained as described above, the release film is peeled off to prepare a strip test piece. The length of the test piece is set to 15 mm and the width is set to 4 mm. Using the dynamic viscoelasticity measuring device DVA-220 manufactured by IT Measurement and Control Co., Ltd., the temperature dispersion of the dynamic viscoelasticity of the above-mentioned strip test piece is measured at a frequency of 10 Hz and a heating rate of 4°C/min in the range of -100°C to 130°C to obtain the storage elastic modulus and dielectric loss tangent (tanδ).

Handling evaluation: Cut two test pieces of 3×3cm from the sheet-shaped adhesive, apply a load of 2kg with the adhesive surfaces of the two pieces overlapping each other, and let it stand at 25°C for 72 hours. After that, the overlapping sheet adhesive was peeled off and the surface condition was evaluated. (evaluation criteria) ○: It can be peeled off, and the surface of the peeled surface is not damaged. △: Peelable, but the surface appearance of the peeled surface deteriorates. ×: Cannot be peeled off.

Evaluation of adhesion: The molded body obtained as described above was subjected to a tensile test using Shimadzu Autograph AG-XPlus in an environment of 25°C, and the 180° peeling adhesive force (unit N/25mm) was measured at a tensile speed of 50 mm/min.

Evaluation of heat resistance: The molded body obtained in the above manner was left to stand in an air supply constant temperature thermostat (trade name: DNF84, manufactured by Yamato Scientific Co., Ltd.) set to 100° C., and the appearance of the molded body after 500 hours was confirmed. (evaluation criteria) ○: The film was not peeled off from the ABS adherend molded body. △: A part of the film is peeled off from the ABS adhered molded body, and the adhered molded body is partially exposed. ×: The film peeled off from the ABS adhered molded body. -: The adhesion after molding is 0N/25mm, so the heat resistance test cannot be performed.

<Example 1> Example of producing copolyester (a1) 83 parts by mass of terephthalic acid, 73 parts by mass of adipic acid, 180 parts by mass of 1,4-butanediol, and 0.1 parts by mass of tetrabutyl titanium were added to a reaction tank equipped with a stirrer, a thermometer, and a cooler for distillation, and an esterification reaction was carried out at 170-220°C for 2 hours. After the esterification reaction was completed, the temperature was raised to 255°C, and the system was slowly depressurized. It took 60 minutes to carry out a polycondensation reaction at 250°C to obtain copolyester (a1). The composition and physical property values are shown in Table 1. In addition, the obtained copolyester (a1) was processed into the aforementioned sheet adhesive and the performance was evaluated. The results are shown in Table 2.

<Example 2> Preparation of copolyester (a2) In a reaction tank equipped with a stirrer, a thermometer, and a distillation cooler, 108 parts by mass of terephthalic acid, 58 parts by mass of isophthalic acid, 180 parts by mass of 1,4-butanediol, and 0.4 parts by mass of tetrabutyl titanium were added, and an esterification reaction was carried out at 170-220°C for 2 hours. After the esterification reaction was completed, 170 parts by weight of polytetramethylene glycol "PTMG1000" (manufactured by Mitsubishi Chemical Corporation, density 0.98 g/cm ³ ) with a number average molecular weight of 1000 and 0.8 parts by weight of hindered phenol antioxidant "Irganox 1330" (manufactured by Ciba-Geigy) were added, the temperature was raised to 255°C, and the system was gradually depressurized. Polycondensation reaction was carried out at 255°C for 60 minutes to obtain copolyester (a2). The composition and physical property values are shown in Table 1. The performance evaluation results are shown in Table 2.

<Example 3~4, Comparative Example 1~4> Example of preparation of copolyesters (a3)~(a8) Copolyesters (a3) and (a6) are prepared by the same method as copolyester (a2), and copolyesters (a4), (a5), (a7) and (a8) are prepared by the same method as copolyester (a1), respectively, by changing the type and amount of each component so as to obtain the resin composition shown in Table 1, to synthesize copolyesters (a3)~(a8). The respective compositions and physical property values are shown in Table 1. In addition, the respective performance evaluation results are shown in Table 2.

＜Comparative Example 5＞ An acrylic adhesive (b1) (Mold Fit 50 manufactured by Nirei Shinka) was used instead of the copolymerized polyester, and performance evaluation was performed in the same manner. The performance evaluation results are shown in Table 2.

[Table 1] Copolyester＜Resin composition (mol%)＞ a1 a2 a3 a4 a5 a6 a7 a8 Polycarboxylic acid components terephthalic acid 50 65 50 35 40 65 50 0 isophthalic acid 0 35 0 20 30 35 20 0 sebacic acid 0 0 0 0 0 0 30 50 Adipic acid 50 0 0 45 30 0 0 50 1,4-Cyclohexanedicarboxylic acid 0 0 50 0 0 0 0 0 Polyol ingredients Ethylene glycol 0 0 0 0 0 0 60 50 1,4-butanediol 100 83 90 100 100 90 0 50 neopentyl glycol 0 0 0 0 0 0 40 0 Polytetramethylene glycol ^※1 0 17 10 0 0 10 0 0 Resin physical properties Aromatic group concentration (mass %) 19 twenty one 12 20 26 25 25 0 Glass transition temperature (℃) -37 -70 -60 -20 -8 -70 7 -60 Melting point(℃) 110 126 107 96 113 139 - 40 Crystallization heat of fusion (J/g) 14.5 12.8 6.31 2.93 16 17 - 87.2 Reduced viscosity (dl/g) 0.9 1.8 1.2 0.9 0.5 1.5 0.7 0.8 Sheet properties Tensile elastic modulus (MPa) 52 37 36 25 103 65 - - Elongation at break(%) 854 940 711 857 80 790 - - Storage elastic modulus at 0℃ (MPa) 106 55 67 81 1013 167 1700 - tanδ peak temperature (℃) -30 -40 -30 -15 8 -16 28 -

[Table 2] Example Comparative example 1 2 3 4 1 2 3 4 5 copolyester a1 a2 a3 a4 a5 a6 a7 a8 b1 Handling 〇 〇 〇 〇 〇 〇 × 〇 × Adhesion(N/25mm) 38 46 47 79 0 0 31 0 32 heat resistance 〇 〇 〇 △ - - × - 〇 ※b1: Acrylic adhesive

As can be seen from Table 2, the copolymerized polyesters of the examples have good handling properties and adhesive properties. In particular, the copolymerized polyesters (a1) to (a3) have a higher melting point and crystallization heat of fusion than the copolymerized polyester (a4), so they also have excellent heat resistance. On the other hand, the copolyester-based aromatic group concentration of Comparative Example 1 was high and did not exhibit adhesiveness. The copolymer polyester system of Comparative Example 2 has a high melting point and does not exhibit adhesiveness. The copolymerized polyester of Comparative Example 3 has no melting point and is poor in blocking resistance (handling properties). The copolyester-based aromatic group concentration of Comparative Example 4 was low and did not exhibit adhesiveness. In Comparative Example 5, an acrylic adhesive was used, but the anti-blocking properties (handling properties) were poor. [Industrial availability]

The copolyester of the present invention has excellent handling properties and good adhesion during three-dimensional thermoforming. It can be bonded to a substrate even with a small amount of heat, so it can be used as an adhesive for three-dimensional thermoforming represented by TOM molding.

Claims (9)

A copolyester, wherein the aromatic group concentration in the copolyester is 5 to 25 mass %, the glass transition temperature is -80 to 10°C, and the melting point is 70 to 130°C. Such as the copolyester of claim 1, wherein the crystallization heat of fusion is 0.5 J/g or more and 20 J/g or less. Such as the copolymer polyester of claim 1 or 2, wherein the elongation at break measured at 25°C is more than 500%. Such as the copolyester of claim 1 or 2, wherein the storage elastic modulus at 0°C is less than 150 MPa. Such as the copolyester of claim 1 or 2, wherein the tensile elastic modulus measured at 25°C is 10~80MPa. A sheet adhesive containing the copolyester of claim 1 or 2. The sheet adhesive of claim 6 is used for three-dimensional thermoforming. A laminated film obtained by laminating the sheet-shaped adhesive agent of claim 6. A molded body obtained by laminating the sheet-like adhesive according to claim 6.