WO2019188922A1 - 熱収縮性ポリエステル系フィルム - Google Patents
熱収縮性ポリエステル系フィルム Download PDFInfo
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- WO2019188922A1 WO2019188922A1 PCT/JP2019/012394 JP2019012394W WO2019188922A1 WO 2019188922 A1 WO2019188922 A1 WO 2019188922A1 JP 2019012394 W JP2019012394 W JP 2019012394W WO 2019188922 A1 WO2019188922 A1 WO 2019188922A1
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- shrinkage
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/181—Acids containing aromatic rings
- C08G63/183—Terephthalic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/199—Acids or hydroxy compounds containing cycloaliphatic rings
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/66—Polyesters containing oxygen in the form of ether groups
- C08G63/668—Polyesters containing oxygen in the form of ether groups derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/672—Dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- 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
- C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
- B29C55/08—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique transverse to the direction of feed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
- B29C61/02—Thermal shrinking
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2467/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
- C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2207/00—Properties characterising the ingredient of the composition
- C08L2207/20—Recycled plastic
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F3/00—Labels, tag tickets, or similar identification or indication means; Seals; Postage or like stamps
- G09F3/02—Forms or constructions
- G09F3/0291—Labels or tickets undergoing a change under particular conditions, e.g. heat, radiation, passage of time
Definitions
- the present invention relates to a heat-shrinkable polyester film suitable for heat-shrinkable label applications.
- polyvinyl chloride resin and polystyrene are used for band packaging for bundling containers such as lunch boxes, as well as for label packaging, cap seals, integrated packaging, etc. that protect glass bottles or plastic bottles and display products.
- a stretched film (so-called heat-shrinkable film) made of a polyester resin or a polyester resin is used.
- the polyvinyl chloride film has low heat resistance and generates hydrogen chloride gas during incineration; it causes dioxins.
- polystyrene film has poor solvent resistance and must use ink with a special composition during printing, and must be incinerated at a high temperature, and a large amount of black smoke is generated with an unpleasant odor during incineration.
- polyester-based heat-shrinkable films are widely used as heat-shrinkable labels because of their high heat resistance, easy incineration, and excellent solvent resistance.
- Patent Document 1 discloses a heat shrinkable film using polylactic acid which is a biomass raw material.
- a heat-shrinkable polyester film mainly composed of ethylene terephthalate (polylactic acid is also a polyester material, but in the present invention, a polyester material refers to a material mainly composed of ethylene terephthalate and is distinguished from polylactic acid. ) Is superior to the polylactic acid type, and a heat-shrinkable polyester film using a biomass raw material is expected.
- Patent Document 2 discloses a polyester film using biomass-derived ethylene glycol, and shows the possibility of reducing the environmental load.
- a heat-shrinkable film using a biomass-derived polyester raw material has not yet been disclosed. This is because in the polyester-based biomass raw material, ethylene glycol is replaced from petroleum-derived to plant-derived.
- a conventional heat-shrinkable polyester film needs to use a copolymerization raw material (amorphous raw material) of a monomer that can be amorphous in order to exhibit heat-shrinkability.
- amorphous raw material a copolymerization raw material of a monomer that can be amorphous in order to exhibit heat-shrinkability.
- the heat shrinkability increases with the increase of the amorphous raw material.
- a conventional heat-shrinkable polyester film generally uses an amorphous polyester raw material (amorphous raw material). This is because it is considered that amorphous molecules are involved in the expression of the shrinkage rate.
- a heat-shrinkable polyester film using an amorphous raw material has a problem that heat resistance is low and thickness unevenness is poor.
- Patent Document 6 PET resin recycled from PET bottles (recycled) A polyester film using 80% by weight of PET as a raw material is disclosed.
- the polyester film described in Patent Document 6 requires that the heat shrinkage rate is small.
- Patent Document 7 discloses a heat-shrinkable polyester film using recycled PET.
- the heat-shrinkable polyester film described in Patent Document 7 expresses heat-shrinkability by containing a predetermined amount of a copolymerizable monomer component other than ethylene terephthalate, has low heat resistance, and has uneven thickness. There is a problem that is bad.
- recycled PET contains only 55 weight% at the maximum, and in order to achieve environmental load reduction, it is preferable that it is higher content.
- the ends of the film are fixed with a solvent, an adhesive, or the like to produce a ring-shaped (tube-shaped) label, and this is covered with a bottle and shrunk.
- the method is adopted.
- the shrinking direction the width direction, the shrinking label can be continuously produced, which is efficient.
- Patent Document 4 discloses a heat-shrinkable film that thermally shrinks in the transverse (width) direction and hardly undergoes thermal shrinkage in the longitudinal (longitudinal) direction, and a manufacturing method thereof.
- a film exhibiting desired heat shrinkage characteristics is produced by laterally uniaxially stretching a film which is made of crystalline polyethylene terephthalate as a raw material and subjected to bending treatment in the longitudinal direction.
- Patent Document 5 discloses a heat-shrinkable polyester film having a low heat shrinkage rate in the width direction (vertical direction) and a small thickness unevenness in the longitudinal direction.
- Patent Document 5 uses a polyester-based unstretched film in which ethylene terephthalate is a main constituent, and a monomer component that can be an amorphous component in all polyester resin components is contained in an amount of 0 mol% to 5 mol%.
- the film is produced by a biaxial stretching method in which the film is longitudinally stretched.
- a stretching method A a simultaneous biaxial stretching machine shown in FIG. After stretching in the width direction (transverse stretching) at a magnification of 5 times to 6 times, the distance between the clips is increased at a temperature of the film Tg or more (Tg + 40 ° C.) to 1.5 times or more and 2.5 times or less. It describes a method of relaxing in the width direction by narrowing the tenter width by 5% or more and 30% or less after transverse stretching while stretching in the longitudinal direction at a magnification (longitudinal stretching).
- the film of Patent Document 4 is disclosed as a heat-shrinkable film that shrinks greatly in the width direction.
- the thermal shrinkage rate at 95 ° C. in the width direction is 12.5% at the maximum, and it cannot be said that the level of shrinkage rate required for the current heat shrink film is satisfied.
- the main shrinkage direction is the longitudinal direction. Therefore, a film whose width direction is the main shrinkage direction and which has a high heat shrinkage in the width direction and a small thickness unevenness has not been disclosed yet. Even if the transverse-to-longitudinal stretching method described in Patent Document 5 is simply changed from longitudinal to transverse stretching, the non-shrinkage direction (longitudinal direction) cannot be relaxed, and the shrinkage ratio in the longitudinal direction becomes high, which is desired. No film can be obtained. Furthermore, even if the longitudinal to lateral stretching is performed, the thermal shrinkage stress in the width direction may be increased.
- the present invention has been made in view of the above circumstances, and its purpose is to provide a heat-shrinkable polyester film and / or recycled PET that uses a raw material derived from biomass resources that does not substantially contain an amorphous component.
- a heat-shrinkable polyester film that is blended and preferably blended with recycled PET in a high ratio, has a high heat shrinkage ratio in the width direction and has a small thickness variation, and a method for producing the same There is to do.
- the present inventors have studied to solve the above problems.
- the preheated film is preheated at a temperature (T1) of (Tg + 40 ° C.) or more and (Tg + 70 ° C.) or less (Tg + 5 ° C.) or more ( (Tg + 40 ° C.) or less at a temperature (T2), and the transversely stretched film is further stretched at a temperature (T3) of (Tg ⁇ 10 ° C.) to (Tg + 15 ° C.) (provided that T1> T2> T3)
- T1> T2> T3 the transverse stretching method is adopted, the shrinkage rate in the longitudinal direction and the width direction can be controlled even in the case of using a polyester in which the ethylene terephthalate unit is 90 mol% or more in 100 mol% of all ester units, and a high heat in the width direction.
- the present inventors have found that the shrinkage rate and the reduction in thickness variation can both
- the configuration of the present invention is as follows. 1. It is a heat-shrinkable polyester film containing ethylene terephthalate units in 90 mol% or more of 100 mol% of all ester units, and at least a part of ethylene glycol and / or terephthalic acid constituting the ethylene terephthalate unit is derived from biomass resources Do you know it, Or contains polyester resin recycled from PET bottles, A heat-shrinkable polyester film characterized by satisfying the following requirements (1) to (4). (1) Thermal contraction rate in the width direction when contracted in 90 ° C. hot water for 10 seconds 50% or more and 75% or less (2) Thermal contraction in the longitudinal direction when contracted in 90 ° C.
- thermo contraction rate in the longitudinal direction is -6% or more and 6% or less when shrinking in hot water of 70 ° C. for 10 seconds
- Thickness unevenness in the width direction is 1% 20% or less
- the heat-shrinkable polyester film according to 1 above which satisfies the following requirement (5).
- the maximum heat shrinkage stress in the width direction when contracted in hot air at 90 ° C. for 30 seconds is 4 MPa or more and 13 MPa. 3.
- the heat-shrinkable polyester film according to 1 or 2 which satisfies the following requirement (6).
- Crystallinity calculated from density is 1% or more and 15% or less. 4.
- a heat-shrinkable polyester film substantially free of an amorphous component or a heat-shrinkable polyester film blended with a high ratio of recycled PET, the heat in the width direction being the main shrinkage direction. It was possible to provide a heat-shrinkable polyester film having a high shrinkage rate and a small thickness unevenness.
- polyester raw material used for heat-shrinkable polyester film has an ethylene terephthalate unit of 90 mol% or more in 100 mol% of all ester units. Preferably it is 95 mol% or more, Most preferably, it is 100 mol%.
- the ethylene terephthalate unit contains ethylene glycol and terephthalic acid as main components. By using ethylene terephthalate, excellent heat resistance and transparency as a heat-shrinkable polyester film can be obtained.
- biomass degree When the ratio of plant-derived carbon to the total number of carbons is defined as the biomass degree, the biomass degree is theoretically 20% when only the ethylene glycol component is derived from plants in the ethylene terephthalate unit.
- terephthalic acid In order to increase the degree of biomass, terephthalic acid also needs to be derived from plants, and the effect of reducing the environmental load increases, but the cost increases.
- Petroleum-derived components and plant-derived components may be used in combination.
- the lower limit of the degree of biomass of the polyester constituting the film is preferably 5% or more, more preferably 10% or more, and further preferably 13% or more. If it is less than the above, the effect on the environmental load reduction may be small.
- the upper limit of the degree of biomass is preferably 20%, more preferably 100%.
- a second preferred mode of the polyester raw material used for the heat-shrinkable polyester film of the present invention is a mode in which recycled PET is contained in an amount of 50 wt% to 100 wt%.
- the most preferable form is 100% by weight.
- the lower limit of the content ratio of recycled PET is preferably 60% by weight, and more preferably 70% by weight.
- polyester used in PET bottles is controlled in crystallinity, and as a result, polyester containing 10 mol% or less isophthalic acid component is used as the acid component. May have.
- the polyester raw material used in the present invention may contain amorphous components (amorphous alcohol component and amorphous acid component), but the proportion of the amorphous alcohol component in 100 mol% of the total alcohol component and the total acid component The total with the ratio of the amorphous acid component in 100 mol% is suppressed to 0 mol% or more and 5 mol% or less.
- the polyester is composed only of an ethylene terephthalate unit, but it is not an active copolymerization, and the ethylene terephthalate unit includes a constituent unit of terephthalic acid and diethylene glycol and / or isophthalic acid. And ethylene glycol constituent units may be present as by-products.
- a preferable content in the case of containing isophthalic acid is 0.5 mol% or more and 5 mol% or less of the isophthalic acid component with respect to all dicarboxylic acids in all polyester resins constituting the polyester film.
- the content of the amorphous component is preferably as low as possible, and most preferably 0 mol%.
- Examples of the monomer of the amorphous acid component include the above-mentioned isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the like.
- Examples of the monomer for the amorphous alcohol component include neopentyl glycol, 1,4-cyclohexanedimethanol, diethylene glycol, 2,2-diethyl 1,3-propanediol, and 2-n-butyl-2- Examples include ethyl-1,3-propanediol, 2,2-isopropyl-1,3-propanediol, 2,2-di-n-butyl-1,3-propanediol, hexanediol, and the like.
- the polyester raw material used in the present invention may use 1,4-butanediol, which is a diol component other than ethylene glycol, as a component other than the above-described ethylene terephthalate and amorphous components.
- 1,4-Butanediol lowers the melting point of the polyester film and is useful as a low Tg component, but it is preferably not contained as much as possible for the purpose of the present invention.
- the preferred content of 1,4-butanediol in the total alcohol component and the total acid component is 10 mol% or less, more preferably 5 mol% or less, and most preferably 0 mol%.
- the polyester raw material used in the present invention may contain various additives as necessary.
- the additive is not particularly limited, and known additives such as waxes, antioxidants, antistatic agents, crystal nucleating agents, viscosity reducers, heat stabilizers, coloring pigments, anti-coloring agents, ultraviolet absorbers, and the like. Is mentioned.
- the polyester raw material is preferably added with fine particles that act as a lubricant in order to improve the workability (slidability) of the film.
- Any fine particles can be selected regardless of the type of inorganic fine particles and organic fine particles.
- the inorganic fine particles include silica, alumina, titanium dioxide, calcium carbonate, kaolin, and barium sulfate.
- the organic fine particles include acrylic resin particles, melamine resin particles, silicone resin particles, and crosslinked polystyrene particles.
- the average particle diameter of the fine particles is preferably in the range of about 0.05 to 3.0 ⁇ m when measured with a Coulter counter.
- the lower limit of the content of the fine particles in the film is preferably 0.01% by weight, more preferably 0.015% by weight, and still more preferably 0.02% by weight. If it is less than 0.01% by weight, the slipperiness may be lowered.
- the upper limit is preferably 1% by weight, more preferably 0.2% by weight, and still more preferably 0.1% by weight. If it exceeds 1% by weight, the transparency may be lowered, which is not preferable.
- the method of blending the fine particles in the polyester raw material is not particularly limited.
- the fine particles can be added at any stage for producing the polyester resin, but after the esterification stage or the completion of the transesterification reaction, the polycondensation is performed. It is preferable to add as a slurry dispersed in ethylene glycol or the like at the stage before the start of the reaction to advance the polycondensation reaction.
- a method of blending a slurry of fine particles dispersed in ethylene glycol or water using a vented kneading extruder and a polyester resin raw material; or a dried fine particle and polyester resin raw material using a kneading extruder You may carry out by the method of blending.
- the intrinsic viscosity of the polyester raw material is preferably in the range of 0.50 to 0.80 dl / g.
- the intrinsic viscosity is more preferably 0.52 dl / g or more and 0.78 dl / g or less, further preferably 0.52 dl / g or more and 0.75 dl / g or less, particularly preferably 0.52 dl / g or more. 0.73 dl / g or less.
- the heat-shrinkable polyester film of the present invention can be subjected to corona treatment, coating treatment, flame treatment, etc. in order to improve the printability and adhesion of the film surface.
- the heat-shrinkable polyester film of the present invention satisfies the above requirements (1) to (4).
- the most significant contribution to the shrinkage finish of the label is the heat shrinkage rate at 90 ° C. defined in (1) in the width direction, and (2) and (3 in the longitudinal direction.
- the heat shrinkage rate at 70 ° C. and 90 ° C. specified in (1)) is technically more difficult to control than the other temperature zones.
- the heat shrinkage rate in the width direction which is the main shrinkage direction defined in (1) is very high, and the heat shrinkage rate in the longitudinal direction in (2) and (3) is low, and It is very useful in that it can provide a heat-shrinkable polyester film having a small thickness variation.
- the heat shrinkable polyester film of the present invention is in the width direction (main shrinkage direction) when immersed in hot water at 90 ° C. for 10 seconds, as defined in (1) above.
- the shrinkage rate is 50% or more and 75% or less.
- the “width direction” is a direction orthogonal to the longitudinal direction (machine direction; Machine Direction; MD), and is also referred to as a transverse direction (TD). If the thermal shrinkage rate in the width direction at 90 ° C. is less than 50%, the film shrinks insufficiently when the container is shrunk on the container or the like, and the film does not adhere cleanly to the container, resulting in poor appearance.
- the thermal contraction rate in the width direction at 90 ° C. is preferably 55% or more and 70% or less, and more preferably 60% or more and 65% or less.
- the heat shrinkable polyester film of the present invention has a heat shrinkage ratio in the longitudinal direction (machine direction, MD) when immersed in hot water at 90 ° C. for 10 seconds, as defined in (2) above. Is -6% or more and 14% or less. If the thermal shrinkage in the longitudinal direction at 90 ° C. is less than ⁇ 6%, it is not preferable because when the container is coated and shrunk, the film tends to be stretched and wrinkled easily and a good shrink appearance cannot be obtained. On the other hand, if the thermal shrinkage in the longitudinal direction at 90 ° C. exceeds 14%, distortion and sink marks are likely to occur after shrinkage, which is not preferable.
- the thermal shrinkage in the longitudinal direction at 90 ° C. is preferably from ⁇ 4% to 12%, more preferably from ⁇ 2% to 10%.
- the heat-shrinkable polyester film of the present invention has a heat shrinkage rate of ⁇ 6% in the longitudinal direction (machine direction, MD) when immersed in hot water at 70 ° C. for 10 seconds as defined in (3) above. It is 6% or less. If the heat shrinkage rate in the longitudinal direction at 70 ° C. is less than ⁇ 6%, it is not preferable because when the container is shrunk, it tends to be stretched too much and become wrinkled, and a good shrink appearance cannot be obtained. On the other hand, if the thermal shrinkage in the longitudinal direction at 70 ° C. exceeds 6%, distortion and sink marks are likely to occur after shrinkage, which is not preferable.
- the thermal shrinkage in the longitudinal direction at 70 ° C. is preferably from ⁇ 4% to 4%, more preferably from ⁇ 2% to 2%.
- the heat-shrinkable polyester film of the present invention has a thickness unevenness of 1% or more and 20% or less when the measurement length is 1 m across the width direction, as defined in (4) above.
- the thickness unevenness in the width direction exceeds 20%, it is preferable because not only appearance defects such as misalignment and wrinkles occur when the film is wound as a roll, but printing defects are likely to occur when the film is printed. Absent.
- the thickness unevenness in the longitudinal direction is preferably 19% or less, and more preferably 18% or less. Although the thickness unevenness in the width direction is preferably as small as possible, it can be considered that about 1% is the limit in consideration of the performance of the film forming apparatus.
- the heat shrinkable polyester film of the present invention has a maximum heat shrinkage stress in the width direction of 4 MPa or more when contracted in hot air at 90 ° C. for 30 seconds. It is preferably 13 MPa or less. In the case of heat shrinkage, if the maximum heat shrinkage stress at 90 ° C. in the width direction exceeds 13 MPa, it is not preferable because an object to be packaged such as a container is easily deformed. On the other hand, the lower the maximum heat shrinkage stress in the width direction, the less the deformation of the object to be packaged, which is preferable, but 4 MPa is the lower limit in the current technical level.
- the crystallinity calculated from the density is preferably 1% or more and 15% or less as defined in (6) above.
- the crystallinity exceeds 15%, the thermal shrinkage in the width direction increases.
- the relationship between the thermal contraction rate and the crystallinity in the width direction will be described later.
- the lower the degree of crystallinity the better the heat shrinkage rate in the width direction, which is preferably 13% or less, more preferably 11% or less.
- the lower limit of the crystallinity is about 1% in the current technical level. The method for measuring the degree of crystallinity is described in the column of Examples.
- the thickness of the heat-shrinkable polyester film according to the present invention is preferably 5 ⁇ m or more and 200 ⁇ m or less, considering that it is used for banding film applications used for binding purposes such as bottle label applications and lunch boxes. It is more preferably 20 ⁇ m or more and 100 ⁇ m. When the thickness exceeds 200 ⁇ m, the weight per area of the film simply increases, which is not economical. On the other hand, if the thickness is less than 5 ⁇ m, the film becomes extremely thin, which makes it difficult to handle in a process such as making a tubular label (poor handling properties).
- the haze value is preferably 2% or more and 13% or less.
- the haze value exceeds 13%, the transparency becomes poor and the appearance may be deteriorated during label production.
- the haze value is more preferably 11% or less, and still more preferably 9% or less. The smaller the haze value, the better.
- the lower limit is about 2%.
- the heat-shrinkable polyester film of the present invention is stretched laterally under the following conditions using an unstretched film obtained by melt-extruding the polyester raw material with an extruder. Can be manufactured. Specifically, it is preheated at a temperature (T1) of (Tg + 40 ° C.) or more and (Tg + 70 ° C.) or less, and the preheated film is transversely stretched at a temperature (T2) of (Tg + 5 ° C.) or more (Tg + 40 ° C.), The transversely stretched film is further stretched at a temperature (T3) of (Tg ⁇ 10 ° C.) or more and (Tg + 15 ° C.) or less.
- T1, T2, and T3 satisfy the relationship of T1>T2> T3.
- heat treatment may be performed at a temperature of (Tg ⁇ 30 ° C.) to Tg.
- the polyester can be obtained by polycondensing the above-mentioned preferred dicarboxylic acid component and diol component by a known method. Usually, two or more kinds of chip-like polyester are mixed and used as a raw material for the film.
- the polyester raw material is preferably dried using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer. After the polyester raw material is dried in this way, it is melted at a temperature of 200 to 300 ° C. using an extruder and extruded into a film.
- a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer.
- the polyester raw material is melted at a temperature of 200 to 300 ° C. using an extruder and extruded into a film.
- any existing method such as a T-die method or a tubular method can be employed.
- an unstretched film can be obtained by rapidly cooling the sheet-like molten resin after extrusion.
- a method of rapidly cooling the molten resin a method of obtaining a substantially unoriented resin sheet by casting the molten resin from a die onto a rotating drum and solidifying by rapid cooling is preferably used.
- the heat-shrinkable polyester film of the present invention can be obtained by stretching the obtained unstretched film in the width (lateral) direction by the method described in detail below.
- a heat-shrinkable polyester film using a conventional amorphous material is generally stretched at a glass transition temperature (Tg) to Tg + 30 ° C. at a stretching ratio of 3.5 to 5.5 times (final stretching). It is manufactured by stretching at a magnification). It is considered that the amorphous molecules are oriented by this stretching condition, and the film has a shrinkage ratio. The shrinkage ratio becomes higher as the stretching temperature is lower or the stretch ratio is higher (that is, the amorphous molecules are oriented). Easier).
- the monomer component (amorphous raw material) which can be an amorphous component as in the present invention is 0 mol% or more and 5 mol% or less and does not substantially contain an amorphous raw material
- the film shrinks if stretched at a magnification of 2 to 2.5 times, but the same magnification as above, that is, stretch of 3.5 to 5.5 times is performed. On the contrary, the shrinkage rate of the film is lowered.
- Comparative Example 1 where the draw ratio was as high as 3.6 times, the shrinkage in the width direction was significantly reduced to 20.4%.
- Comparative Examples 5 and 6 in Table 3 to be described later are all made from a polyester raw material having a Tg of 74 ° C. and a temperature of 83 to 90 ° C. (Comparative Example 5) or 80 ° C. (Comparative Example 6). This is an example of producing a film by transverse stretching at 6 times (Comparative Example 5) or 2.3 times (Comparative Example 6).
- FIG. 4 of Non-Patent Document 1 shows the relationship between stress (horizontal axis) and birefringence (vertical axis) in uniaxial stretching of polyethylene terephthalate fiber, and the state of change in molecular orientation is read from this figure. be able to. That is, in the region where the draw ratio DR is about 2 times, the stress and the birefringence are in a linear relationship, and when the drawing is stopped, the stress is relaxed and the birefringence is lowered.
- the decrease in birefringence indicates relaxation of molecular chains, and when replaced with a film, it is considered that the film contracts (expresses shrinkage).
- the draw ratio DR exceeds 2
- the linear relationship between stress and birefringence becomes difficult to be established, and no reduction in birefringence is observed even when the drawing is stopped.
- This phenomenon is considered to indicate a decrease in shrinkage due to orientation crystallization. From this, even if it is a case where the amorphous raw material is not substantially contained as in the present invention, it is considered that the shrinkage rate can be expressed in the film as long as the orientation crystallization by stretching does not occur. .
- the present inventors do not make the stretching process in general high-temperature stretching (constant) as described above, but in a process in which molecules are hardly oriented by high-temperature stretching and a process in which molecules are actively oriented by low-temperature stretching.
- the shrinkage rate can be expressed by aligning only amorphous molecules while suppressing the decrease in the shrinkage rate due to orientation crystallization, and the thickness unevenness can be suppressed to a low level.
- the film is preheated at a temperature T1, stretched at a temperature T2, and then stretched at a temperature T3 (T1> T2> T3), whereby only amorphous molecules are contained in the film. It was found that the thermal contraction rate in the longitudinal direction and the width direction can be controlled, and thickness unevenness in the width direction can be reduced.
- the preheating zone is preheated at a temperature T1 of (Tg + 40 ° C.) or more and (Tg + 70 ° C.) or less.
- T1 a temperature of (Tg + 40 ° C.) or more and (Tg + 70 ° C.) or less.
- the preheating temperature T1 is (less than Tg + 40 ° C.), the stress applied in the longitudinal direction increases due to neck-in caused by transverse stretching, and the thermal shrinkage rate in the longitudinal direction tends to exceed the upper limit of 6%, which is not preferable.
- the preheating temperature T1 exceeds (Tg + 70 ° C.)
- the thickness unevenness in the width direction is deteriorated and easily exceeds 20% of the upper limit.
- the preheating temperature T1 is more preferably (Tg + 45 ° C.) or more and (Tg + 65 ° C.) or less, and more preferably (Tg + 50 ° C.) or more (Tg + 60 ° C.) or less.
- the passage time of the preheating zone it is preferable to control the passage time of the preheating zone to 2 seconds or more and 10 seconds or less so that the preheating temperature T1 is reached. If the passage time of the preheating zone is less than 2 seconds, the transverse stretching at T2 in the next step is started before the film reaches the preheating temperature T1. Therefore, the same problem as when the preheating temperature T1 is less than (Tg + 40 ° C.) occurs.
- the longer the passage time of the preheating zone the more preferable the temperature of the film easily reaches the preheating temperature T1, but when the passage time is too long, the temperature of the preheating zone is set to exceed the cold crystallization temperature. This is not preferable because crystallization of the unstretched film is excessively promoted. Furthermore, the longer the passing time through the preheating zone, the more the production facilities increase, which is not preferable. A passage time of the preheating zone of 10 seconds is sufficient.
- the film preheated at the temperature T1 is stretched transversely at a temperature T2 of (Tg + 5 ° C.) or more and (Tg + 40 ° C.) or less (sometimes referred to as first transverse stretching).
- T2 a temperature of (Tg + 5 ° C.) or more and (Tg + 40 ° C.) or less.
- the temperature T2 in the first lateral stretching is set lower than the preheating temperature T1 to (Tg + 5 ° C.) or more and (Tg + 40 ° C.) or less. Control.
- the temperature T2 in the first transverse stretching is preferably (Tg + 10 ° C.) or more and (Tg + 35 ° C.) or less, more preferably (Tg + 15 ° C.) or more and (Tg + 30 ° C.) or less.
- the draw ratio in the first transverse drawing is preferably 1.5 times or more and 2.5 times or less.
- the draw ratio in the first transverse stretch is less than 1.5 times, the effect of suppressing orientation crystallization is reduced, the shrinkage rate in the film width direction tends to be less than 50%, and the shrinkage rate in the longitudinal direction is 6 %, It is not preferable because it tends to exceed%.
- the draw ratio exceeds 5 times in the first transverse drawing the thickness unevenness in the width direction tends to exceed 20%, which is not preferable.
- the stretching ratio in the first lateral stretching is more preferably 1.6 times or more and 2.4 times or less, and further preferably 1.7 times or more and 2.3 times or less.
- the transversely stretched film is further stretched at a temperature T3 of (Tg ⁇ 10 ° C.) or more and (Tg + 15 ° C.) or less (sometimes referred to as second transverse stretching).
- T3 a temperature of (Tg ⁇ 10 ° C.) or more and (Tg + 15 ° C.) or less.
- the temperature T3 in the second transverse stretching is more preferably (Tg ⁇ 7 ° C.) or more and (Tg + 12 ° C.) or less, and more preferably (Tg ⁇ 4 ° C.) or more and (Tg + 9 ° C.) or less.
- the draw ratio in the second transverse drawing is preferably 1.5 times or more and 2.5 times or less. If the draw ratio in the second transverse drawing is less than 1.5 times, the thickness unevenness in the width direction is deteriorated. On the other hand, when the draw ratio exceeds 2.5 times in the second transverse stretching, not only the shrinkage rate in the width direction tends to decrease, but also the shrinkage stress in the width direction increases.
- the stretching ratio in the second transverse stretching is more preferably 1.6 times or more and 2.4 times or less, and further preferably 1.7 times or more and 2.3 times or less.
- the final draw ratio (the product of the draw ratio in the first transverse drawing and the draw ratio in the second transverse draw) is preferably 3 to 5.5 times. If the final draw ratio is less than 3, not only the shrinkage rate in the width direction tends to decrease, but also the thickness unevenness in the width direction deteriorates. On the other hand, when the final draw ratio exceeds 5.5, breakage tends to occur during stretching in the width direction.
- the final draw ratio is more preferably 3.1 times or more and 5.4 times or less, and further preferably 3.2 times or more and 5.3 times or less.
- the preheating temperature T1, the temperature T2 in the first stretching, and the temperature T3 in the second stretching satisfy the relationship of T1> T2> T3.
- a desired film can be obtained by performing transverse stretching so that each of T1, T2, and T3 satisfies the above range while satisfying this relationship.
- the film that has been subjected to transverse stretching as described above may be heat-treated in a state where both ends in the width direction are held with clips in the tenter, if necessary.
- the heat treatment means that the heat treatment is performed at a temperature of (Tg ⁇ 20 ° C.) or more and Tg or less for 1 second or more and 9 seconds or less.
- Such heat treatment can be preferably used because it can suppress a decrease in the heat shrinkage rate and improve the dimensional stability after storage over time.
- the heat treatment temperature is lower than (Tg ⁇ 20 ° C.), the above-mentioned effect due to the heat treatment is not exhibited effectively.
- the thermal shrinkage in the width direction tends to be below the lower limit of 50%.
- the temperature at the time of heat processing is below the temperature T3 in 2nd extending
- Example 8 the heating temperature after transverse stretching is 50 ° C., and the above temperature range Is not considered as an example in which the heat treatment is performed in the present invention.
- Example 8 since the heating temperature after transverse stretching was set to 75 ° C., it is considered that the heat treatment in the present invention was performed. The longer the heat treatment time, the easier it is to exert the effect. However, if the heat treatment time is too long, the equipment becomes enormous, so it is preferable to control the heat treatment time between 1 second and 9 seconds. More preferably, it is 5 seconds or more and 8 seconds or less.
- relaxation in the width direction can be performed by reducing the distance between the gripping clips in the tenter. Thereby, the dimensional change after a time storage and the fall of a heat contraction characteristic can be suppressed.
- Maximum heat shrinkage stress A sample having a main shrinkage direction (width direction) length of 200 mm and a width (longitudinal direction) of 20 mm was cut out from the polyester film, and using a high elongation measuring machine with a heating furnace (Tensilon, registered trademark of Orientec Corporation). It was measured. The heating furnace was previously heated to 90 ° C., and the distance between chucks was 100 mm. Blowing of the heating furnace was temporarily stopped, the heating furnace door was opened, the sample was attached to the chuck, and then the heating furnace door was quickly closed to restart the blowing. The heat shrinkage stress in the width direction when shrinking in hot air at 90 ° C. for 30 seconds was measured, and the maximum value was defined as the maximum heat shrinkage stress (MPa).
- MPa maximum heat shrinkage stress
- dc 1.455 g / cm 3 (density of polyethylene terephthalate complete crystal) da: 1.335 g / cm 3 (density of polyethylene terephthalate completely amorphous)
- Tg glass transition point
- biomass degree The proportion of plant-derived carbon in the total number of carbons measured according to ASTM D6866 was defined as the biomass degree.
- polyester raw material A In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial recirculating cooler, 100 mol% of dimethyl terephthalate (DMT) as a petroleum-derived dicarboxylic acid component, and as a petroleum-derived polyhydric alcohol component Charge 100 mol% ethylene glycol (EG) so that ethylene glycol is 2.2 times the molar ratio of dimethyl terephthalate, and polycondensate 0.05 mol% zinc acetate as the transesterification catalyst with respect to the acid component.
- DMT dimethyl terephthalate
- EG ethylene glycol
- antimony trioxide was added in an amount of 0.225 mol% based on the acid component, and a transesterification reaction was carried out while distilling off the produced methanol out of the system. Thereafter, a polycondensation reaction was performed at 280 ° C. under a reduced pressure of 26.7 Pa to obtain a polyester raw material A having an intrinsic viscosity of 0.58 dl / g.
- the intrinsic viscosity is obtained by dissolving 0.2 g of polyester in 50 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60/40, weight ratio) and using an Ostwald viscometer at 30 ° C. (Dl / g) was measured.
- This polyester raw material A is polyethylene terephthalate.
- the composition of the monomer component of the polyester raw material A is shown in Table 1.
- Table 1 the content of each monomer component in 100 mol% of the total acid component is listed in the column of “acid component”, and each column in 100 mol% of the total polyhydric alcohol component is listed in the column of “polyhydric alcohol component”. The monomer component content is shown.
- Polyester raw material B was synthesized in the same manner as polyester A, except that petroleum-derived ethylene glycol was replaced with plant-derived ethylene glycol in the synthesis of polyester raw material A.
- Polyester raw materials C to F having different monomer components were obtained as shown in Table 1 by the same method as the above polyester raw material A.
- the polyester raw material C was produced by adding SiO 2 (Silicia 266 manufactured by Fuji Silysia Co., Ltd .; average particle size 1.5 ⁇ m) as a lubricant at a ratio of 7,000 ppm with respect to the polyester.
- SiO 2 Siliconicia 266 manufactured by Fuji Silysia Co., Ltd .
- average particle size 1.5 ⁇ m average particle size 1.5 ⁇ m
- TPA is terephthalic acid
- IPA is isophthalic acid
- BD is 1,4-butanediol
- NPG is neopentyl glycol
- CHDM is 1,4-cyclohexanedimethanol
- DEG is a by-product diethylene glycol.
- the intrinsic viscosity of each polyester raw material is C: 0.58 dl / g, D: 0.72 dl / g, E: 0.80 dl / g, F: 1.20 dl / g, G: 0.70 dl / g, respectively. there were.
- polyester raw material G After washing away the remaining foreign substances such as beverages from beverage PET bottles, the flakes obtained by pulverization are melted with an extruder, and the filter is changed to a finer one with a mesh size. Fine foreign matters were filtered out and filtered with a filter having the smallest opening size of 50 ⁇ m for the third time to obtain a polyester raw material B as a PET bottle recycling raw material.
- Polyester B and polyester C were mixed at a mass ratio of 95: 5 and charged into an extruder. This mixed resin was melted at 280 ° C., extruded from a T-die, wound on a rotating metal roll cooled to a surface temperature of 30 ° C., and rapidly cooled to obtain an unstretched film having a thickness of about 150 ⁇ m. The Tg of the unstretched film was 75 ° C. The obtained unstretched film was guided to a transverse stretcher (tenter) and preheated at 130 ° C. for 5 seconds. The preheated film was continuously led to the first half zone of transverse stretching and stretched at 90 ° C. until 2.0 times.
- This mixed resin was melted at 280 ° C., extruded from a T-die, wound on a rotating metal roll cooled to a surface temperature of 30 ° C., and rapidly cooled to obtain an unstretched film having a thickness of about 150 ⁇ m.
- Examples 2 to 4 Films of Examples 2 to 4 were produced in the same manner as in Example 1 except that the conditions for transverse stretching and the polyester raw materials were changed as shown in Table 2 in Example 1.
- Comparative Example 1 The polyester raw material A and the polyester raw material C were mixed at 95: 5 and charged into an extruder, and the raw materials were melted and extruded in the same manner as in Example 1. Thereafter, a film of Comparative Example 1 was produced in the same manner as in Example 1 except that the conditions for transverse stretching were changed as shown in Table 2.
- Comparative Example 4 Polyester raw material B, polyester raw material C, polyester raw material E, and polyester raw material F are mixed at a mass ratio of 18: 5: 67: 10 and charged into an extruder, and the raw materials are melted in the same manner as in Example 1. Extruded. Thereafter, a film of Comparative Example 4 was produced in the same manner as in Example 1 except that the conditions for transverse stretching were changed as shown in Table 2. Thus, the characteristic of each film obtained was evaluated by said method. These results are also shown in Table 2.
- the heat-shrinkable films of Examples 1 to 4 that satisfy the requirements of the present invention use a biomass raw material, and use polyethylene terephthalate having a very low proportion of the amorphous component of 1 mol%.
- the heat shrinkage rate in the width direction is high, the thickness unevenness in the width direction is reduced, the heat shrinkage rate in the longitudinal direction is kept low, and the shrinkage finish when coated on the label is also good ( Evaluation 4 or 5).
- Comparative Example 1 did not use biomass raw materials, and did not satisfy the requirements of the present invention. Furthermore, since the temperature T1 at the time of preheating was as low as 90 ° C., the thermal shrinkage rate at 90 ° C. in the width direction was as low as 20.4%, and the shrinkage finish of the label was remarkably reduced (Evaluation 1).
- Comparative Example 4 since a polyester film containing a large amount of amorphous components was used, the thickness unevenness in the width direction was as large as 23.4%. In Comparative Example 4, an amorphous raw material other than polyethylene terephthalate is used, and the method of calculating the crystallinity according to the above formula 3 cannot be applied. Therefore, the column of Table 2 is described as “ ⁇ ”.
- Polyester G and polyester C were mixed at a mass ratio of 95: 5 and charged into an extruder. This mixed resin was melted at 280 ° C., extruded from a T-die, wound on a rotating metal roll cooled to a surface temperature of 30 ° C., and rapidly cooled to obtain an unstretched film having a thickness of about 150 ⁇ m.
- the Tg of the unstretched film was 74 ° C.
- the obtained unstretched film was guided to a transverse stretching machine (tenter) and preheated at 140 ° C. for 5 seconds. The preheated film was continuously led to the first half zone of transverse stretching, and stretched transversely at 95 ° C. until 2.0 times.
- Example 6 to 10 Comparative Examples 5 to 8
- Example 5 Example 5 above, Examples 6 to 10 and Comparative Examples 5 to 8 were made in the same manner as Example 5 except that the raw material blending ratios of polyesters A and B and the conditions for transverse stretching were changed as shown in Table 3. A film was produced.
- a recycled PET raw material was used in an amount of 60% by weight or more, and a raw material in which the ratio of the amorphous component was suppressed to 10 mol% or less was used. Nevertheless, the heat shrinkage rate in the width direction is high, the thickness unevenness in the width direction is reduced, the heat shrinkage rate in the longitudinal direction is also kept low, and the shrink finish when coated on the label is also good. (Evaluation 4 or 5).
- the comparative example 5 uses the recycled PET raw material, since the temperature T1 at the time of preheating was as low as 95 ° C., the thermal shrinkage rate at 90 ° C. in the width direction was as low as 25.6%. Since the heat shrinkage stress at 90 ° C. was as high as 16.4%, the shrinkage finish of the label was remarkably lowered (Evaluation 1).
- Comparative Example 7 uses recycled PET raw material, the temperature T2 at the time of stretching was as low as 70 ° C., so the thermal shrinkage rate at 70 ° C. in the longitudinal direction was as high as 14.1%, and the shrinkage of the label was finished. The property decreased (Evaluation 2).
- Comparative Example 9 did not satisfy the requirements of the present invention because the physical properties such as shrinkage satisfied the requirements of the present invention, but the amount of ethylene glycol monomer was small (that is, the amount of ethylene terephthalate units was small).
- an amorphous raw material other than polyethylene terephthalate is used, and the method of calculating the crystallinity according to the above formula 3 cannot be applied. Therefore, the column of Table 3 is described as “ ⁇ ”.
- Comparative Example 10 did not satisfy the requirements of the present invention because the amount of ethylene glycol monomer was small (ie, the amount of ethylene terephthalate unit was small). Moreover, since the ratio of the amorphous component was as high as 23%, the thickness unevenness in the width direction was as high as 23.4%. In Comparative Example 10, an amorphous raw material other than polyethylene terephthalate is used, and the calculation method of the crystallinity according to the above formula 3 cannot be applied. Therefore, the column of Table 3 is described as “ ⁇ ”.
- the heat-shrinkable polyester film of the present invention uses a biomass raw material PET bottle recycled raw material and has the above characteristics, so that it can be used for banding film used for binding of bottle labels, lunch boxes, etc. It can be suitably used for and can contribute to reducing the environmental load.
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Abstract
Description
従来の石油由来の原料は有限であり、焼却処分される際に大気へ二酸化炭素を放出する問題がある。一方、バイオマス原料は再生可能であり、仮に焼却処分されたとしても植物が取り込んだ二酸化炭素を大気に戻すことになるため、石油由来原料よりも二酸化炭素の発生量を減らすことができる点で有用である。例えば特許文献1には、バイオマス原料であるポリ乳酸を用いた熱収縮性フィルムが開示されている。しかし特許文献1では、ポリ乳酸系の弱点である収縮仕上がり性の悪さを補うために石油由来のオレフィン系素材と積層しているため、依然として環境負荷低減には寄与できていない。一方、エチレンテレフタレートを主成分とした熱収縮性ポリエステル系フィルム(ポリ乳酸もポリエステル系素材だが、本発明においては、ポリエステル系素材とはエチレンテレフタレートを主成分とする素材を指し、ポリ乳酸と区別する)の収縮仕上がり性は、ポリ乳酸系よりも優れているため、バイオマス原料を用いた熱収縮性ポリエステル系フィルムが期待されている。
上述のように、従来の熱収縮性ポリエステル系フィルムは、非晶質のポリエステル原料(非晶質原料)を用いることが一般的である。これは、収縮率の発現には非晶質分子が関与していると考えられているためである。しかし、非晶質原料を用いた熱収縮性ポリエステル系フィルムは、耐熱性が低く、厚み斑が悪いという問題がある。
1.エチレンテレフタレートユニットを全エステルユニット100モル%中、90モル%以上含有する熱収縮性ポリエステル系フィルムであり、該エチレンテレフタレートユニットを構成するエチレングリコール及び/またはテレフタル酸の少なくとも一部がバイオマス資源に由来しているか、
あるいはPETボトルからリサイクルされたポリエステル樹脂を含有し、
下記要件(1)~(4)を満たすことを特徴とする熱収縮性ポリエステル系フィルム。(1)90℃の温湯中に10秒間収縮させたときの幅方向における熱収縮率が50%以上75%以下
(2)90℃の温湯中に10秒間収縮させたときの長手方向における熱収縮率が-6%以上14%以下
(3)70℃の温湯中に10秒間収縮させたときの長手方向における熱収縮率が-6%以上6%以下
(4)幅方向における厚み斑が1%以上20%以下
2.更に下記要件(5)を満たすものである上記1に記載の熱収縮性ポリエステル系フィルム。
(5)90℃の熱風中で30秒間収縮させたときの幅方向における最大熱収縮応力が4MPa以上13MPa
3.更に下記要件(6)を満たすものである上記1または2に記載の熱収縮性ポリエステル系フィルム。
(6)密度から算出した結晶化度が1%以上15%以下
4.前記エチレンテレフタレートを構成するエチレングリコール及び/またはテレフタル酸の少なくとも一部がバイオマス資源に由来している、上記1~3のいずれかに記載の熱収縮性ポリエステル系フィルム。
5.前記PETボトルからリサイクルされたポリエステル樹脂を50重量%以上100重量%以下で含有する、上記1~4のいずれかに記載の熱収縮性ポリエステル系フィルム。
6.ポリエステルフィルムを構成する全ポリエステル樹脂中の全ジカルボン酸成分に対するイソフタル酸成分含有率が0.5モル%以上5モル%以下である、上記1~5のいずれかに記載の熱収縮性ポリエステル系フィルム。
本発明の熱収縮性ポリエステル系フィルムに用いるポリエステル原料は、エチレンテレフタレートユニットを全エステルユニット100モル%中、90モル%以上有する。好ましくは95モル%以上であり、最も好ましくは100モル%である。エチレンテレフタレートユニットは、エチレングリコールおよびテレフタル酸を主な構成成分として含有する。エチレンテレフタレートを用いることにより、熱収縮性ポリエステル系フィルムとして優れた耐熱性と透明性を得ることができる。また、エチレンテレフタレートユニットを構成するエチレングリコール及び/またはテレフタル酸はその少なくとも一部がバイオマス原料であることが第1の好ましい様態である。バイオマス原料を用いることで、環境負荷低減に寄与することができる。全炭素数に占める植物由来炭素の割合をバイオマス度としたとき、エチレンテレフタレートユニットにおいて、エチレングリコール成分のみを全て植物由来としたときバイオマス度は理論上20%となる。バイオマス度をそれより大きくするには、テレフタル酸も植物由来とする必要があり、環境負荷低減の効果は大きくなるがコスト高となる。該エチレングリコール成分とテレフタル酸成分については、石油由来の成分と植物由来の成分を併用してもよい。フィルムを構成するポリエステルのバイオマス度の下限は、好ましくは5%以上、より好ましくは10%以上、さらに好ましくは13%以上である。上記未満であると環境負荷低減に対して効果が小さいことがある。バイオマス度の上限は好ましくは20%、より好ましくは100%である。
また非晶質アルコール成分(ジオール成分)のモノマーとしては、例えばネオペンチルグリコール、1,4-シクロヘキサンジメタノール、ジエチレングリコール、2,2-ジエチル1,3-プロパンジオール、2-n-ブチル-2-エチル-1,3-プロパンジオール、2,2-イソプロピル-1,3-プロパンジオール、2,2-ジ-n-ブチル-1,3-プロパンジオール、ヘキサンジオール等が挙げられる。
本発明の熱収縮性ポリエステル系フィルムは上記(1)~(4)の要件を満足する。熱収縮性フィルムをボトルのラベル用途に用いる場合、ラベルの収縮仕上がり性に最も寄与するのが、幅方向では(1)に規定する90℃における熱収縮率、長手方向では(2)、(3)に規定する70℃、90℃における熱収縮率であり、当該温度帯における熱収縮率の制御が他の温度帯より技術的に難しい。本発明によれば、(1)に規定する主収縮方向である幅方向の熱収縮率が非常に高く、(2)、(3)における長手向の熱収縮率が低いフィルムであって、且つ、厚み斑の小さい熱収縮性ポリエステル系フィルムを提供できた点で非常に有用である。
本発明の熱収縮性ポリエステル系フィルムは、上記(1)に規定するとおり、90℃の温湯中に10秒間浸漬させたときの幅方向(主収縮方向)における収縮率が50%以上75%以下である。ここで「幅方向」とは長手方向(機械方向、Machine Direction;MD)と直交する方向であり、横方向(Transverse Direction;TD)とも呼ばれる。90℃における幅方向の熱収縮率が50%未満であると、容器等に被覆収縮させる際に、フィルムの収縮が不足して容器にきれいに密着せず、外観不良が起こるため好ましくない。一方、90℃における幅方向の熱収縮率が75%を超えると、容器等に被覆収縮させる際に収縮速度が極端に速くなってしまい、フィルムの歪み等が発生するため好ましくない。90℃における幅方向の熱収縮率は、55%以上70%以下が好ましく、60%以上65%以下がより好ましい。
本発明の熱収縮性ポリエステル系フィルムは上記(2)に規定するとおり、90℃の温湯中に10秒間浸漬させたときの長手方向(機械方向、MD)における熱収縮率が-6%以上14%以下である。90℃における長手方向の熱収縮率が-6%未満であると、容器等に被覆収縮させる際に、伸びが生じすぎてシワになり易く、良好な収縮外観を得ることができないので好ましくない。一方、90℃における長手方向の熱収縮率が14%を超えると、収縮後に歪みやヒケが生じ易くなるので好ましくない。90℃における長手方向の熱収縮率は、-4%以上12%以下が好ましく、-2%以上10%以下がより好ましい。
本発明の熱収縮性ポリエステル系フィルムは、上記(4)に規定するとおり、幅方向にわたって測定長さを1mとした場合の厚み斑が1%以上20%以下である。幅方向の厚み斑が20%を超えると、フィルムをロールとして巻き取ったときに端面ズレやシワ等の外観不良が起こるだけでなく、フィルムを印刷するときに印刷不良が発生し易くなるので好ましくない。長手方向の厚み斑は、19%以下が好ましく、18%以下がより好ましい。幅方向の厚み斑は小さいほど好ましいが、製膜装置の性能等を考慮すると1%程度が限界であると考えらえる。
本発明の熱収縮性ポリエステル系フィルムは、上記(5)に規定するとおり、90℃の熱風中で30秒間収縮させたときの幅方向における最大熱収縮応力が4MPa以上13MPa以下であることが好ましい。熱収縮の際、幅方向の90℃での最大熱収縮応力が13MPaを上回ると、容器等の被包装対象物が変形し易くなるため好ましくない。一方、幅方向における最大熱収縮応力は低いほど被包装対象物の変形が少なくなるため好ましいが、現状の技術水準では4MPaが下限である。
本発明の熱収縮性ポリエステル系フィルムは、上記(6)に規定するとおり、密度から算出した結晶化度が1%以上15%以下であることが好ましい。上記結晶化度が15%を上回ると、幅方向における熱収縮率が増加する。幅方向における熱収縮率と結晶化度との関係については、後述する。上記結晶化度は低ければ低いほど、幅方向における熱収縮率が増加するため良く、13%以下がより好ましく、11%以下が更に好ましい。なお上記結晶化度は、現在の技術水準では1%程度が下限である。結晶化度の測定方法は、実施例の欄に記載する。
本発明に係る熱収縮性ポリエステル系フィルムの厚みは、ボトルのラベル用途や弁当箱等の結束目的で使用するバンディングフィルム用途等に用いられることを考慮すると、5μm以上200μm以下が好ましく、20μm以上100μmがより好ましい。厚みが200μmを超えると、単にフィルムの面積あたりの重量が増加するだけで経済的でない。一方、厚みが5μmを下回るとフィルムが極端に薄くなるため、チューブ状ラベルにする等の工程で扱い難く(ハンドリング性が悪く)なってしまう。
また、ヘイズ値は2%以上13%以下が好ましい。ヘイズ値が13%を超えると、透明性が不良となり、ラベル作成の際に見栄えが悪くなる虞があるので好ましくない。ヘイズ値は、11%以下がより好ましく、9%以下が更に好ましい。なおヘイズ値は小さいほど好ましいが、実用上必要な滑り性を付与する目的でフィルムに所定量の滑剤を添加せざるを得ないこと等を考慮すると、2%程度が下限になる。
本発明の熱収縮性ポリエステル系フィルムは、上記ポリエステル原料を押出機により溶融押し出しして得られた未延伸フィルムを用いて、下記条件で横延伸することによって製造することができる。具体的には、(Tg+40℃)以上(Tg+70℃)以下の温度(T1)で予熱し、前記予熱されたフィルムを(Tg+5℃)以上(Tg+40℃)以下の温度(T2)で横延伸し、前記横延伸されたフィルムを(Tg-10℃)以上(Tg+15℃)以下の温度(T3)で更に延伸する。ここで前記T1、T2、T3はT1>T2>T3の関係を満足する。必要に応じて、前記T3での第2横延伸の後、(Tg-30℃)以上Tg以下の温度で熱処理しても良い。なお、ポリエステルは、前述した好適なジカルボン酸成分とジオール成分とを公知の方法で重縮合させることによって得ることができる。また通常は、チップ状のポリエステルを2種以上混合してフィルムの原料として使用する。
原料樹脂を溶融押し出しする際には、ポリエステル原料をホッパードライヤー、パドルドライヤー等の乾燥機、または真空乾燥機を用いて乾燥するのが好ましい。このようにしてポリエステル原料を乾燥した後、押出機を利用して200~300℃の温度で溶融し、フィルム状に押し出す。押し出しに際しては、Tダイ法、チューブラー法等、既存の任意の方法を採用することができる。
そして、押し出し後のシート状の溶融樹脂を急冷することによって未延伸フィルムを得ることができる。なお、溶融樹脂を急冷する方法としては、溶融樹脂を口金から回転ドラム上にキャストして急冷固化することにより実質的に未配向の樹脂シートを得る方法が好適に用いられる。
得られた未延伸フィルムを、以下に詳述する方法で幅(横)方向へ延伸することにより、本発明の熱収縮性ポリエステル系フィルムを得ることができる。
以下、本発明の熱収縮性ポリエステル系フィルムを得るための延伸方法について、従来の熱収縮性ポリエステル系フィルムの製膜方法、および非特許文献1及び2を引用して分子構造との差異を考慮しつつ、詳細に説明する。
フィルムの収縮挙動を支配する分子構造の詳細は、未だ明らかになっていない部分が多いが、大まかには配向した非晶質分子が収縮特性に関与していると考えられている。そのため、通常、熱収縮性ポリエステル系フィルムは非晶質原料を使用し、収縮させたい方向(主収縮方向、通常は幅方向)へ延伸することによって製造される。従来の非晶質原料を用いた熱収縮性ポリエステル系フィルムは、一般的にはガラス転移温度(Tg)からTg+30℃の温度で、3.5倍から5.5倍程度の延伸倍率(最終延伸倍率)で延伸して製造されている。この延伸条件によって非晶質分子が配向し、フィルムに収縮率が備わると考えられており、延伸温度が低いほど、または延伸倍率が高いほど収縮率は高くなる(すなわち非晶質分子が配向し易くなる)。
第1横延伸での温度T2は、(Tg+10℃)以上(Tg+35℃)以下がより好ましく、(Tg+15℃)以上(Tg+30℃)以下が更に好ましい。
上記のようにして横延伸を行ったフィルムは、必要に応じて、テンター内で幅方向の両端際をクリップで把持した状態で熱処理しても良い。ここで熱処理とは、(Tg-20℃)以上Tg以下の温度で1秒以上9秒以下、熱処理することを意味する。このような熱処理により、熱収縮率の低下を抑制できる他、経時保管後の寸法安定性が向上するため、好ましく用いられる。熱処理温度が(Tg-20℃)より低いと、熱処理による上記効果が有効に発揮されない。一方、熱処理温度がTgより高いと、幅方向の熱収縮率が下限の50%を下回り易くなる。
なお、熱処理時の温度は、第2延伸での温度T3以下であることが好ましい。
熱処理時間は長いほど効果を発揮し易くなるが、あまり長いと設備が巨大化するので、1秒以上9秒以下に制御することが好ましい。より好ましくは、5秒以上、8秒以下である。
また、熱処理工程においては、テンター内の把持用クリップ間の距離を縮めることにより、幅方向へのリラックスを実施することもできる。これにより、経時保管後の寸法変化や熱収縮特性の低下を抑制することができる。
ポリエステル系フィルムを10cm×10cmの正方形に裁断し、所定温度[(90℃または70℃)±0.5℃]の温湯中に無荷重状態で10秒間浸漬して熱収縮させた後、25℃±0.5℃の水中に10秒間浸漬し、水中から引き出してフィルムの縦および横方向の寸法を測定し、下式1に従ってそれぞれの熱収縮率を求めた。熱収縮率の大きい方向を主収縮方向(幅方向)とした。
熱収縮率(%)={(収縮前の長さ-収縮後の長さ)/収縮前の長さ}×100 式1
フィルムロールから、フィルム長手方向の寸法40mm×フィルム幅方向の寸法500mmの幅広な帯状のフィルム試料をサンプリングし、ミクロン測定器株式会社製の連続接触式厚み計を用いて、測定速度5m/minで上記フィルム試料の幅方向に沿って連続的に厚みを測定した(測定長さは400mm)。測定時の最大厚みをTmax.、最小厚みをTmin.、平均厚みをTave.とし、下式2に従ってフィルムの幅方向の厚み斑を算出した。
厚み斑(%)={(Tmax.-Tmin.)/Tave.}×100 式2
ポリエステル系フィルムから、主収縮方向(幅方向)の長さが200mm、幅(長手方向)20mmのサンプルを切り出し、加熱炉付き強伸度測定機(テンシロン、オリエンテック社の登録商標)を用いて測定した。加熱炉は予め90℃に加熱しておき、チャック間距離は100mmとした。加熱炉の送風を一旦止めて加熱炉の扉を開け、上記サンプルをチャックに取付けた後、速やかに加熱炉の扉を閉めて送風を再開した。90℃熱風中で30秒間収縮させたときの幅方向における熱収縮応力を測定し、その最大値を最大熱収縮応力(MPa)とした。
JIS K7136に準拠して、ヘイズメータ「500A」(日本電色工業株式会社製)を用いて測定した。測定は2回行い、その平均値を求めた。
JIS-K-7112の密度勾配管法により、硝酸カルシウム水溶液を用いて約3mm四方のサンプルの密度dを測定し、下式3に従って結晶化度を測定した。
結晶化度(%)={dc×(d-da)/(d×(dc-da)}×100 式3
dc:1.455g/cm3(ポリエチレンテレフタレート完全結晶の密度)
da:1.335g/cm3(ポリエチレンテレフタレート完全非晶の密度)
d: サンプルの密度(g/cm3)
セイコー電子工業株式会社社製の示差走査熱量計(型式:DSC220)を用いて、JIS-K7121-1987に従ってTgを求めた。詳細には未延伸フィルム10mgを、-40℃から120℃まで昇温速度10℃/分で昇温し、吸熱曲線を測定した。得られた吸熱曲線の変曲点の前後に接線を引き、その交点をガラス転移点(Tg;℃)とした。
ポリエステル系フィルムの端部をインパルスシーラー(富士インパルス社製)で溶着し、幅方向を周方向とした円筒状ラベルを得た。このラベルを、市販のPETボトル(内容物入り;伊藤園社製の「おーいお茶」)に被せて、85℃に調整したスチームに通して熱収縮させた(トンネル通過時間30秒)。ラベルの収縮仕上がり性を、以下の基準に従って目視で5段階評価した。以下に記載の欠点とは、飛び上がり、シワ、収縮不足、ラベル端部折れ込み、収縮白化等を意味する。
5:仕上がり性最良(欠点なし)
4:仕上がり性良(欠点1箇所あり)
3:欠点2箇所あり
2:欠点3~5箇所あり
1:欠点多数あり(6箇所以上)
ASTM D6866に従い測定した、全炭素数に占める植物由来炭素の割合をバイオマス度とした。
ポリエステル原料Aの合成
撹拌機、温度計および部分環流式冷却器を備えたステンレススチール製オートクレーブに、石油由来のジカルボン酸成分としてジメチルテレフタレート(DMT)100モル%と、石油由来の多価アルコール成分としてエチレングリコール(EG)100モル%とを、エチレングリコールがモル比でジメチルテレフタレートの2.2倍になるように仕込み、エステル交換触媒として酢酸亜鉛を酸成分に対して0.05モル%、重縮合触媒として三酸化アンチモンを酸成分に対して0.225モル%添加し、生成するメタノールを系外へ留去しながらエステル交換反応を行った。その後、280℃で26.7Paの減圧下にて重縮合反応を行い、固有粘度0.58dl/gのポリエステル原料Aを得た。なお固有粘度は、ポリエステル0.2gをフェノール/1,1,2,2-テトラクロルエタン(60/40、重量比)の混合溶媒50mLに溶解し、30℃でオストワルド粘度計を用いて固有粘度(dl/g)を測定した。このポリエステル原料Aはポリエチレンテレフタレートである。ポリエステル原料Aのモノマー成分の組成を表1に示す。表1中、「酸成分」の欄には全酸成分100モル%に占める各モノマー成分の含有量を、「多価アルコール成分」の欄には全多価アルコール成分100モル%中に占める各モノマー成分の含有量を示している。
ポリエステル原料Aの合成において、石油由来のエチレングリコールを植物由来のエチレングリコールに置き換えた以外は、ポリエステルAと同様の方法によりポリエステル原料Bを合成した。
上記ポリエステル原料Aと同様の方法により、表1に示すように、モノマー成分の異なるポリエステル原料C~Fを得た。なお、ポリエステル原料Cは、滑剤としてSiO2(富士シリシア社製サイリシア266;平均粒径1.5μm)をポリエステルに対して7,000ppmの割合で添加して製造した。各ポリエステル原料は、適宜チップ状にした。表1において、TPAはテレフタル酸、IPAはイソフタル酸、BDは1,4-ブタンジオール、NPGはネオペンチルグリコール、CHDMは1,4-シクロヘキサンジメタノール、DEGは副生成物のジエチレングリコールである。各ポリエステル原料の固有粘度は、それぞれ、C:0.58dl/g、D:0.72dl/g,E:0.80dl/g,F:1.20dl/g,G:0.70dl/gであった。
飲料用PETボトルから残りの飲料などの異物を洗い流した後、粉砕して得たフレークを押出機で溶融し、順次目開きサイズの細かなものにフィルタを変えて2回更に細かな異物を濾別し、3回目に50μmの最も小さな目開きサイズのフィルタで濾別して、PETボトルリサイクル原料であるポリエステル原料Bを得た。得られた樹脂の組成は、テレフタル酸/イソフタル酸//エチレングリコール/ジエチレングリコール=95.0/5.0//98/2(モル%)で、固有粘度は0.70dl/gであった。
ポリエステルBおよびポリエステルCを質量比95:5で混合して押出機に投入した。この混合樹脂を280℃で溶融させてTダイから押出し、表面温度30℃に冷却された回転する金属ロールに巻き付けて急冷することにより、厚さ約150μmの未延伸フィルムを得た。未延伸フィルムのTgは75℃であった。
得られた未延伸フィルムを横延伸機(テンター)に導き、130℃で5秒間の予熱を行った。予熱後のフィルムは連続して横延伸前半ゾーンに導き、90℃で2.0倍になるまで横延伸した。続いて、横延伸後半ゾーンでは82℃で1.9倍になるまで横延伸した。最終的な横延伸倍率は3.8倍であった。最後に熱処理ゾーンにて50℃で3秒間熱処理した後、冷却し、両縁部を裁断除去して幅500mmでロール状に巻き取ることによって、厚さ40μmの横延伸フィルムを所定の長さにわたって連続的に製造し、実施例1のフィルムを得た。
上記実施例1において、横延伸の条件及びポリエステル原料を表2のように変更したこと以外は実施例1と同様にして実施例2~4のフィルムを製造した。
ポリエステル原料Aおよびポリエステル原料Cを95:5で混合して押出機に投入し、実施例1と同様の方法で原料を溶融させて押出した。その後、横延伸の条件を表2のように変更したこと以外は実施例1と同様にして比較例1のフィルムを製造した。
上記実施例1において、横延伸の条件を表2のように変更したこと以外は実施例1と同様にして比較例2、3のフィルムを製造した。
ポリエステル原料B、ポリエステル原料C、ポリエステル原料E、ポリエステル原料Fを質量比18:5:67:10の割合で混合して押出機に投入し、実施例1と同様の方法で原料を溶融させて押出した。その後、横延伸の条件を表2のように変更したこと以外は実施例1と同様にして比較例4のフィルムを製造した。
このようにして得られた各フィルムの特性を上記の方法で評価した。これらの結果を表2に併記する。
ポリエステルGおよびポリエステルCを質量比95:5で混合して押出機に投入した。この混合樹脂を280℃で溶融させてTダイから押出し、表面温度30℃に冷却された回転する金属ロールに巻き付けて急冷することにより、厚さ約150μmの未延伸フィルムを得た。未延伸フィルムのTgは74℃であった。
得られた未延伸フィルムを横延伸機(テンター)に導き、140℃で5秒間の予熱を行った。予熱後のフィルムは連続して横延伸前半ゾーンに導き、95℃で2.0倍になるまで横延伸した。続いて、横延伸後半ゾーンでは82℃で1.9倍になるまで横延伸した。最終的な横延伸倍率は3.8倍であった。最後に熱処理ゾーンにて50℃で3秒間熱処理した後、冷却し、両縁部を裁断除去して幅500mmでロール状に巻き取ることによって、厚さ40μmの横延伸フィルムを所定の長さにわたって連続的に製造し、実施例5のフィルムを得た。
上記実施例5において、ポリエステルAとBの原料配合比率と横延伸の条件を表3のように変更したこと以外は実施例5と同様にして実施例6~10、および比較例5~8のフィルムを製造した。
ポリエステル原料A、ポリエステル原料G、ポリエステル原料C、ポリエステル原料D、ポリエステル原料Fを質量比27:40:5:18:10の割合で混合して押出機に投入した。この混合樹脂を280℃で溶融させてTダイから押出し、表面温度30℃に冷却された回転する金属ロールに巻き付けて急冷することにより、厚さ約150μmの未延伸フィルムを得た。未延伸フィルムのTgは70℃であった。
次いで、横延伸の条件を表3のように変更したこと以外は上記実施例5と同様にして比較例9のフィルムを製造した。
ポリエステル原料G、ポリエステル原料C、ポリエステル原料E、ポリエステル原料Fを質量比18:5:67:10の割合で混合して押出機に投入した。この混合樹脂を280℃で溶融させてTダイから押出し、表面温度30℃に冷却された回転する金属ロールに巻き付けて急冷することにより、厚さ約150μmの未延伸フィルムを得た。未延伸フィルムのTgは68℃であった。
次いで、横延伸の条件を表3のように変更したこと以外は上記実施例5と同様にして比較例10のフィルムを製造した。
Claims (6)
- エチレンテレフタレートユニットを全エステルユニット100モル%中、90モル%以上含有する熱収縮性ポリエステル系フィルムであり、
該エチレンテレフタレートユニットを構成するエチレングリコール及び/またはテレフタル酸の少なくとも一部がバイオマス資源に由来しているか、
あるいはPETボトルからリサイクルされたポリエステル樹脂を含有し、
下記要件(1)~(4)を満たすことを特徴とする熱収縮性ポリエステル系フィルム。(1)90℃の温湯中に10秒間収縮させたときの幅方向における熱収縮率が50%以上75%以下
(2)90℃の温湯中に10秒間収縮させたときの長手方向における熱収縮率が-6%以上14%以下
(3)70℃の温湯中に10秒間収縮させたときの長手方向における熱収縮率が-6%以上6%以下
(4)幅方向における厚み斑が1%以上20%以下 - 更に下記要件(5)を満たすものである請求項1に記載の熱収縮性ポリエステル系フィルム。
(5)90℃の熱風中で30秒間収縮させたときの幅方向における最大熱収縮応力が4MPa以上13MPa以下 - 更に下記要件(6)を満たすものである請求項1または2に記載の熱収縮性ポリエステル系フィルム。
(6)密度から算出した結晶化度が1%以上15%以下 - 前記エチレンテレフタレートを構成するエチレングリコール及び/またはテレフタル酸の少なくとも一部がバイオマス資源に由来している、請求項1~3のいずれか1項に記載の熱収縮性ポリエステル系フィルム。
- 前記PETボトルからリサイクルされたポリエステル樹脂を50重量%以上100重量%以下で含有する、請求項1~4のいずれか1項に記載の熱収縮性ポリエステル系フィルム。
- ポリエステルフィルムを構成する全ポリエステル樹脂中の全ジカルボン酸成分に対するイソフタル酸成分含有率が0.5モル%以上5モル%以下である、請求項1~5のいずれか1項に記載の熱収縮性ポリエステル系フィルム。
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US20210024708A1 (en) | 2021-01-28 |
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EP3778727A1 (en) | 2021-02-17 |
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