Polyester film and laminate

Abstract

To provide a polyester film which can reduce environmental load and which is comparable in physical properties such as transparency and mechanical properties to conventional polyester films produced from fossil fuel-derived raw materials, and a laminate including the polyester film.SOLUTION: The polyester film of the present disclosure includes a polyester composed of diol units and dicarboxylic acid units, wherein the diol units include ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to polyester films and laminates. [Background technology]

[0002] Polyesters are widely used in various industrial applications due to their excellent mechanical properties, chemical stability, heat resistance, transparency, etc., and their low cost. Polyesters are obtained by polycondensation of diol units and dicarboxylic acid units. For example, polyethylene terephthalate is produced by esterifying ethylene glycol and terephthalic acid as raw materials, followed by polycondensation. These raw materials are produced from petroleum, a fossil fuel. For example, ethylene glycol is industrially produced from ethylene, and terephthalic acid is industrially produced from xylene.

[0003] In recent years, with growing calls for the creation of a circular economy, there has been a desire to move away from fossil fuels in the materials sector, just as there is in energy. Therefore, the production of polyester from raw materials other than fossil fuels, such as biomass, is being considered. Biomass is a non-exhaustible resource, an industrial resource derived from the constituent materials of living organisms. The carbon contained in biomass comes from carbon dioxide absorbed from the atmosphere through photosynthesis during the growth process of living organisms. Therefore, even if carbon dioxide is emitted when biomass is burned, it is thought that the amount of carbon dioxide in the atmosphere does not increase overall. For this reason, biomass is attracting attention as a carbon-neutral renewable energy source. Recently, the practical application of biomass plastics made from these biomass raw materials has progressed rapidly, and attempts have been made to produce polyester, a general-purpose polymer material, from these biomass raw materials (for example, Patent Documents 1 and 2). By using polyester produced from biomass-derived raw materials (biomass polyester) instead of polyester produced using fossil fuel-derived raw materials, it becomes possible to reduce the amount of fossil fuel used and the environmental burden.

[0004] Bioethanol, which is used to produce biomass polyester, can be produced by sugar fermentation from molasses, a non-edible raw material. However, it is known from experience that the yield of crops such as sugarcane is greatly affected by weather factors. Therefore, there are concerns that climate change will make it difficult to stably procure sugarcane, the raw material for bioethanol. Ethanol, which is also used as a raw material for plastics, has been produced from resources that are neither fossil fuels nor biomass. For example, ethanol has been produced by microbial fermentation using carbon monoxide present in exhaust gases emitted from steel mills and factories as a raw material (see, for example, Patent Document 3). Ethylene glycol has also been produced by electrolyzing carbon dioxide present in exhaust gases emitted from steel mills and factories (see, for example, Patent Document 4). Furthermore, the production of polyesters from these compounds has also been considered. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2011-527348 [Patent Document 2] Special Publication No. 2012-519748 [Patent Document 3] Special Publication No. 2011-512869 [Patent Document 4] Japanese Patent Application Publication No. 2018-123390 Summary of the Invention [Problem to be solved by the invention]

[0006] Containers have been produced from polyesters produced from fossil fuel-derived raw materials or biomass-derived raw materials for some time. However, it was unclear whether films produced from polyesters produced using ethanol derived from carbon monoxide gas or ethylene glycol derived from carbon dioxide gas would exhibit the same transparency and mechanical properties as conventional films.

[0007] Therefore, an object of the present disclosure is to provide a polyester film that can reduce the environmental load and is comparable in physical properties such as transparency and mechanical properties to conventional polyester films produced from raw materials derived from fossil fuels. Another object of the present disclosure is to provide a laminate comprising the polyester film. [Means for solving the problem]

[0008] The present inventors have found that polyester films produced using ethylene glycol produced from carbon monoxide gas or carbon dioxide gas as raw materials are comparable in physical properties, such as transparency and mechanical properties, to conventional polyester films produced from raw materials derived from fossil fuels. The present disclosure was completed based on this finding and through further investigation.

[0009] The present disclosure is solved by the following embodiments. <1> A polyester film comprising a polyester consisting of a diol unit and a dicarboxylic acid unit, The polyester film, wherein the diol unit contains ethylene glycol derived from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. <2> The carbon dioxide molecule content is 1.1 x 10 18 pcs / g or more 3.0×10 18 pieces / g or less, <1> The polyester film according to claim 1. <3> The water molecule content is 8.6 x 10 19 pcs / g or more 2.5×10 20 pieces / g or less, <1> or <2> The polyester film according to claim 1. <4> The dicarboxylic acid unit includes at least one selected from the group consisting of terephthalic acid derived from a fossil fuel, terephthalic acid derived from biomass, and terephthalic acid derived from carbon dioxide gas. <1> ~ <3> 1. The polyester film according to claim 1 . <5> <1> ~ <4> An optical film comprising the polyester film according to any one of the above. <6> <1> ~ <4> A laminate comprising the polyester film according to any one of the above. [Effects of the Invention]

[0010] The present disclosure can provide a polyester film that can reduce the environmental load and is comparable in physical properties such as transparency and mechanical properties to conventional polyester films produced from raw materials derived from fossil fuels. The present disclosure can also provide a laminate including the polyester film. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view simply illustrating an example of the configuration of a polyester film according to the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view simply illustrating an example of the configuration of a laminate including a polyester film according to the present disclosure. [Figure 3] FIG. 1 is a perspective view simply showing an example of a standing pouch. [Figure 4] FIG. 2 is a cross-sectional view showing a simplified example of the configuration of a laminate that forms a side sheet of a standing pouch. [Figure 5] FIG. 10 is a cross-sectional view simply showing an example of another configuration of a laminate forming a side sheet of a standing pouch. [Figure 6] FIG. 1 is a front view showing a simplified example of a pillow bag. [Figure 7] FIG. 1 is a front view showing a simplified example of a three-sided sealed bag. [Figure 8] FIG. 1 is a front view showing a simplified example of a four-side sealed bag. [Figure 9] FIG. 1 is a partial cross-sectional view showing an example of a tube container. [Figure 10] FIG. 1 is a cross-sectional view simply showing an example of the configuration of a laminate that forms a cylindrical body portion of a tube container. [Figure 11] FIG. 10 is a cross-sectional view simply showing an example of another configuration of a laminate that forms the cylindrical body of a tube container. [Figure 12] FIG. 1 is a perspective view simply illustrating an example of a liquid-holding paper container. [Figure 13] FIG. 2 is a cross-sectional view simply showing an example of the configuration of a laminate that forms a liquid-storing paper container. [Figure 14] FIG. 1 is a perspective view showing a simplified example of a paper cup with a portion cut away. [Figure 15] FIG. 2 is a cross-sectional view showing a simplified example of the configuration of a laminate that forms the body of a paper cup. [Figure 16] FIG. 1 is an explanatory diagram showing an example of an outline of a method for manufacturing a paper cup. [Figure 17] 1 is a graph showing the measurement results of the transmittance of polyester films of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] [polyester] The polyester film according to the present disclosure comprises a polyester composed of diol units and dicarboxylic acid units, and the diol units contain ethylene glycol produced from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. The term "polyester" refers to a polymer formed by ester bonds. Such polyesters are typically obtained by polycondensation of diol units and dicarboxylic acid units. That is, the polyester contained in the polyester film is obtained by a polycondensation reaction using ethylene glycol as a diol unit and dicarboxylic acid as a dicarboxylic acid unit, which are derived from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

[0013] Ethylene glycol made from carbon monoxide gas and ethylene glycol made from carbon dioxide gas will be described below.

[0014] [Ethylene glycol made from carbon monoxide gas] Ethylene glycol using carbon monoxide gas as a raw material can be produced from ethanol using carbon monoxide gas as a raw material. For example, ethylene glycol using carbon monoxide gas as a raw material can be obtained by, for example, producing ethanol using carbon monoxide gas as a raw material and then converting it into ethylene oxide using a conventionally known method.

[0015] <Microbial fermentation> Ethanol, which is made from carbon monoxide gas, can be obtained by microbial fermentation.

[0016] Microbial fermentation is carried out, for example, in a fermenter filled with a culture solution containing water and microorganisms. A feed gas containing carbon monoxide gas is supplied into the fermenter, and the carbon monoxide gas is converted into ethanol inside the fermenter. The feed gas may contain carbon dioxide, nitrogen, oxygen, etc. in addition to carbon monoxide.

[0017] The fermenter is preferably a continuous fermentation apparatus, and may be any of agitation type, airlift type, bubble column type, loop type, open bond type, and photobio type. The raw material gas and the culture solution may be continuously supplied to the fermenter, but it is not necessary to supply the raw material gas and the culture solution simultaneously, and the raw material gas may be supplied to a fermenter to which the culture solution has been previously supplied. The raw material gas is generally blown into the fermenter through a sparger or the like.

[0018] The culture medium is not particularly limited as long as it has an appropriate composition for culturing microorganisms, but is a liquid containing water as the main component and nutrients (e.g., vitamins, phosphoric acid, etc.) dissolved or dispersed in this water.

[0019] The temperature of the fermenter is preferably controlled to 40° C. or less. By controlling the temperature to 40° C. or less, the microorganisms in the fermenter do not die, and ethanol is efficiently produced by the raw material gas coming into contact with the microorganisms. The temperature of the fermenter is more preferably 38°C or lower, and in order to enhance the activity of the microorganisms, is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher.

[0020] The microorganism (species) that ferments the feed gas is not particularly limited as long as it can produce ethanol by microbial fermentation of the feed gas using carbon monoxide as the main feedstock. For example, the microorganism (species) is preferably one that produces ethanol from the feed gas through the fermentation action of gas-utilizing bacteria. Among gas-utilizing bacteria, the genus Clostridium is preferred, and Clostridium autoethanogenum is more preferred, from the viewpoints of gas utilization and culture stability. Examples are provided in more detail below.

[0021] Gas-utilizing bacteria include both eubacteria and archaebacteria. Examples of true bacteria include bacteria of the genus Clostridium, Moorella, Acetobacterium, Carboxydocella, Rhodopseudomonas, Eubacterium, Butyribacterium, Oligotropha, Bradyrhizobium, and the aerobic hydrogen-oxidizing bacteria Larsotonia.

[0022] On the other hand, examples of archaea include bacteria of the genus Methanobacterium, bacteria of the genus Methanobrevibacter, bacteria of the genus Methanocalculus, bacteria of the genus Methanococcus, bacteria of the genus Methanosarcina, bacteria of the genus Methanosphaera, bacteria of the genus Methanothermobacter, Metha Examples include bacteria of the genus Nothrix, bacteria of the genus Methanoculleus, bacteria of the genus Methanofollis, bacteria of the genus Methanogenium, bacteria of the genus Methanospirillium, bacteria of the genus Methanosaeta, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, bacteria of the genus Arcaheoglobus, and the like. Among these, as archaea, bacteria of the genus Methanosarcina, bacteria of the genus Methanococcus, bacteria of the genus Methanothermobacter, bacteria of the genus Methanothrix, bacteria of the genus Thermococcus, bacteria of the genus Thermofilum, and bacteria of the genus Archaeoglobus are preferred.

[0023] Furthermore, due to their excellent ability to assimilate carbon monoxide and carbon dioxide, archaea are preferably bacteria of the genus Methanosarcina, Methanothermobactor, or Methanococcus, with Methanosarcina or Methanococcus being particularly preferred. Specific examples of Methanosarcina bacteria include Methanosarcina barkeri, Methanosarcina mazei, and Methanosarcina acetivorans.

[0024] Among the gas-utilizing bacteria listed above, it is preferable to select and use bacteria with high ethanol production capacity, such as Clostridium autoethanogenum, Clostridium ljungdahlii, Clostridium aceticum, Clostridium carboxidivorans, Moorella thermoacetica, and Acetobacterium woodii.

[0025] Ethanol produced by microbial fermentation is obtained, for example, as an ethanol-containing liquid mixed with a culture solution. Ethanol can be separated from this ethanol-containing liquid using a separation device. Examples of separation devices include solid-liquid separators, distillation devices, and separation membranes, but it is preferable to use a solid-liquid separator and a distillation device in combination. Below, we will specifically explain the separation process performed using a solid-liquid separator and a distillation device in combination.

[0026] The ethanol-containing liquid obtained by microbial fermentation is separated in a solid-liquid separation device into a solid component mainly composed of microorganisms and a liquid component containing ethanol. The ethanol-containing liquid obtained by microbial fermentation contains, in addition to the target ethanol, microorganisms contained in the fermenter and their dead bodies as solid components, so solid-liquid separation is performed to remove these. Examples of solid-liquid separation devices include filters, centrifuges, and devices that use solution precipitation. The solid-liquid separation device may also be a device (e.g., a heat drying device) that evaporates the liquid component containing ethanol from the ethanol-containing liquid and separates it from the solid component. In this case, the liquid component containing the target ethanol may be entirely evaporated, or the liquid component may be partially evaporated so that the target ethanol is preferentially evaporated.

[0027] The liquid component separated by solid-liquid separation is further distilled in a distillation apparatus to separate the target product, ethanol. Separation by distillation allows for the production of large amounts of highly purified ethanol through simple operations. When distillation is performed, a known distillation apparatus such as a distillation column may be used. Furthermore, the distillation is performed, for example, so that the distillate contains the target product, ethanol, at a high purity, while the bottoms (i.e., the distillation residue) contains water as the main component (for example, 70% by mass or more, preferably 90% by mass or more). By performing the distillation in this manner, the target product, ethanol, and water can be largely separated.

[0028] The temperature inside the distillation apparatus during ethanol distillation is not particularly limited, but is preferably 100° C. or lower, more preferably 95° C. or lower, and preferably 70° C. or higher. By setting the temperature inside the distillation apparatus within the above range, ethanol can be reliably separated from other components such as water. The pressure inside the distillation apparatus during ethanol distillation may be normal pressure, but is preferably less than atmospheric pressure, more preferably 60 kPa or more and 150 kPa or less (gauge pressure). By setting the pressure inside the distillation apparatus within this range, the ethanol separation efficiency can be improved, and the ethanol yield can be increased.

[0029] [Ethylene glycol made from carbon dioxide gas] Ethylene glycol can be produced from carbon dioxide gas by electrolysis. A method for producing ethylene glycol from carbon dioxide gas by electrolysis will be described below.

[0030] <Electrolysis> Electrolysis can be carried out, for example, using an electrolysis cell comprising an anode, a cathode, and an ion exchange membrane positioned to separate the anode and the cathode.

[0031] The anode causes an oxidation reaction of water (H2O) to produce oxygen (O2) and hydrogen ions (H +) or hydroxide ions (OH - ) to generate oxygen (O2) and water (H2O). On the other hand, the cathode reacts with the hydrogen ions (H + ) and electrons (e - ) to reduce carbon dioxide (CO2) and to produce carbon compounds such as ethylene glycol (C2H6O2). In this way, by reducing carbon dioxide on the cathode side of the electrolytic cell, ethylene glycol can be produced using carbon dioxide as a raw material.

[0032] The anode is preferably mainly composed of a catalytic material capable of reducing the overvoltage of the reaction that oxidizes water or hydroxide ions. Examples of such catalytic materials include metals such as platinum (Pt), palladium (Pd), and nickel (Ni), alloys and intermetallic compounds containing these metals, binary metal oxides such as manganese oxide (Mn-O), iridium oxide (Ir-O), nickel oxide (Ni-O), cobalt oxide (Co-O), iron oxide (Fe-O), tin oxide (Sn-O), indium oxide (In-O), ruthenium oxide (Ru-O), lithium oxide (Li-O), and lanthanum oxide (La-O), ternary metal oxides such as Ni-Co-O, Ni-Fe-O, La-Co-O, Ni-La-O, and Sr-Fe-O, quaternary metal oxides such as Pb-Ru-Ir-O and La-Sr-Co-O, and metal complexes such as Ru complexes and Fe complexes.

[0033] The cathode is preferably made of a catalytic material capable of reducing the overvoltage of the carbon dioxide reduction reaction. Examples of such catalytic materials include metals such as gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), titanium (Ti), cadmium (Cd), zinc (Zn), indium (In), gallium (Ga), lead (Pb), and tin (Sn), metal materials such as alloys and intermetallic compounds containing at least one of these metals, carbon materials such as carbon (C), graphene, CNT (carbon nanotubes), fullerene, and Ketjenblack, and metal complexes such as Ru complexes and Re complexes.

[0034] [Diol unit] The diol unit used in the present disclosure does not have to be limited to ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide. That is, ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide may be used in combination with another diol. Even when used in combination with another diol, the present disclosure aims to reduce the environmental impact as long as ethylene glycol made from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide is used.

[0035] Other diols include diols derived from fossil fuels and diols derived from biomass.

[0036] As the fossil fuel-derived diol, a compound having two or more, preferably two to eight hydroxyl groups per molecule can be used. Specifically, the fossil fuel-derived diol is not particularly limited and conventionally known compounds can be used, such as polypropylene glycol (PPG), neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG), butylene glycol (BG), hexamethylene glycol, triethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, 1,9-nonanediol, and 3-methyl-1,5-pentanediol. These may be used alone or in combination of two or more.

[0037] Examples of biomass-derived diols that can be used include aliphatic diols obtained from plant materials such as corn, sugarcane, cassava, and sago palm. Examples of biomass-derived aliphatic diols include polypropylene glycol (PPG), neopentyl glycol (NPG), ethylene glycol (EG), diethylene glycol (DEG), butylene glycol (BG), and hexamethylene glycol, all of which can be obtained from plant materials by the following methods. These may be used alone or in combination.

[0038] Biomass-derived polypropylene glycol is produced by a fermentation method in which glucose is obtained by decomposing plant raw materials, via 3-hydroxypropylaldehyde (HPA) from glycerol. Compared to polypropylene glycol produced by the EO production method, polypropylene glycol produced by a biomethod such as the fermentation method is preferable in terms of safety, as useful by-products such as lactic acid can be obtained, and production costs can be kept low. Biomass-derived butylene glycol can be produced by producing glycol from plant raw materials, fermenting the glycol, obtaining succinic acid, and then hydrogenating the resulting succinic acid. Biomass-derived ethylene glycol can be produced, for example, from bioethanol obtained by a conventional method via ethylene.

[0039] [Dicarboxylic acid unit] The dicarboxylic acid unit of the polyester is, for example, a dicarboxylic acid derived from a fossil fuel, and examples of the dicarboxylic acid derived from a fossil fuel include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof, without limitation. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, butyl esters, etc. Among these, terephthalic acid is preferred, and dimethyl terephthalate is preferred as a derivative of aromatic dicarboxylic acid. Specific examples of aliphatic dicarboxylic acids include linear or alicyclic dicarboxylic acids typically having 2 to 40 carbon atoms, such as oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid. Derivatives of aliphatic dicarboxylic acids include lower alkyl esters of the above aliphatic dicarboxylic acids, such as methyl esters, ethyl esters, propyl esters, and butyl esters, as well as cyclic acid anhydrides of the above aliphatic dicarboxylic acids, such as succinic anhydride. Among these, adipic acid, succinic acid, dimer acid, or a mixture thereof is preferred, with those containing succinic acid as the main component being particularly preferred. More preferred derivatives of aliphatic dicarboxylic acids include methyl esters of adipic acid and succinic acid, or a mixture thereof.

[0040] Furthermore, the dicarboxylic acid units of the polyester may be derived from biomass. Examples of biomass-derived dicarboxylic acids that can be used include aliphatic dicarboxylic acids obtained from plant materials such as renewable plant-derived oils such as soybean oil, linseed oil, tung oil, coconut oil, palm oil, and castor oil, as well as regenerated oils obtained by recycling waste cooking oils containing these oils as a main component. Examples of biomass-derived aliphatic dicarboxylic acids include sebacic acid, succinic acid, phthalic acid, adipic acid, glutaric acid, and dimer acid. For example, sebacic acid is produced by alkaline pyrolysis of ricinoleic acid obtained from castor oil, with heptyl alcohol as a by-product. Furthermore, biomass-derived aromatic dicarboxylic acids can be produced by, for example, producing isobutanol from corn, sugars, or wood, converting the isobutanol into isobutylene, dimerizing the isobutane to produce isooctene, synthesizing p-xylene through radical cleavage, recombination, and cyclization, and then oxidizing the resulting p-xylene (WO 2009 / 079213). When a biomass-derived dicarboxylic acid is used as the dicarboxylic acid unit, in the present disclosure, it is particularly preferable to use biomass-derived terephthalic acid.

[0041] The dicarboxylic acid unit of the polyester may be a dicarboxylic acid produced from carbon dioxide gas. An example of a dicarboxylic acid produced from carbon dioxide gas is terephthalic acid, which is produced from carbon dioxide gas. Terephthalic acid produced from carbon dioxide gas can be produced, for example, by using a composite catalyst containing chromium oxide and a specific H-ZSM-5 zeolite to produce p-xylene from carbon dioxide gas and hydrogen gas as raw materials, and then oxidizing the p-xylene (Japanese Patent Laid-Open Publication No. 2019-205969).

[0042] These dicarboxylic acids can be used alone or in combination of two or more.

[0043] The polyester may be a copolymerized polyester containing the diol unit and dicarboxylic acid unit, as well as a third copolymerization component. Specific examples of the copolymerization component include a bifunctional oxycarboxylic acid, and at least one polyfunctional compound selected from the group consisting of a trifunctional or higher polyhydric alcohol, a trifunctional or higher polycarboxylic acid and / or its anhydride, and a trifunctional or higher oxycarboxylic acid for forming a crosslinked structure. Among these copolymerization components, bifunctional and / or trifunctional or higher oxycarboxylic acids are particularly preferred because they tend to facilitate the production of copolymerized polyesters with a high degree of polymerization. Among these, the use of trifunctional or higher oxycarboxylic acids is most preferred because a very small amount of the oxycarboxylic acid can easily produce a polyester with a high degree of polymerization without the need for a chain extender, as described below.

[0044] The polyester may also be a high-molecular-weight polyester obtained by chain-extending (coupling) these copolymer polyesters. Chain extenders such as carbonate compounds and diisocyanate compounds can also be used, but the amount thereof is usually 10 mol % or less, preferably 5 mol % or less, and more preferably 3 mol % or less of carbonate bonds and urethane bonds relative to 100 mol % of all monomer units constituting the polyester.

[0045] Specific examples of carbonate compounds include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl carbonate, etc. In addition, carbonate compounds composed of the same or different hydroxy compounds derived from hydroxy compounds such as phenols and alcohols can also be used.

[0046] Specific examples of the diisocyanate compound include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0047] The polyester used in the present disclosure can be obtained by a conventionally known method of polycondensing the above-mentioned diol unit and dicarboxylic acid unit. Specifically, it can be produced by a general melt polymerization method in which an esterification reaction and / or transesterification reaction between the above-mentioned diol unit and dicarboxylic acid unit is carried out, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent.

[0048] The amount of diol used in producing the polyester is substantially equimolar to 100 moles of the dicarboxylic acid or its derivative. However, since distillates are generally produced during the esterification and / or transesterification reaction and / or polycondensation reaction, the diol is generally used in an excess of 0.1 mol % or more and 20 mol % or less.

[0049] The polycondensation reaction is preferably carried out in the presence of a polymerization catalyst. The timing of adding the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction, and the catalyst may be added when the raw materials are charged or when pressure reduction is initiated.

[0050] Polymerization catalysts typically include compounds containing metal elements from Groups 1 to 14 of the periodic table, excluding hydrogen and carbon. Specific examples include compounds containing organic groups, such as carboxylates, alkoxy salts, organic sulfonates, or β-diketonate salts, containing at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium, as well as inorganic compounds, such as oxides and halides, of the aforementioned metals, and mixtures thereof. Among these, metal compounds containing titanium, zirconium, germanium, zinc, aluminum, magnesium, or calcium, or mixtures thereof, are preferred, with titanium compounds, zirconium compounds, or germanium compounds being particularly preferred. Furthermore, because a catalyst in a molten or dissolved state during polymerization increases the polymerization rate, it is preferred that the catalyst be liquid during polymerization or soluble in an ester oligomer or polyester.

[0051] The titanium compound is preferably a tetraalkyl titanate, specifically tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, or a mixture thereof. Titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium (diisoproxide)acetylacetonate, titanium bis(ammonium lactate)dihydroxide, titanium bis(ethylacetoacetate)diisopropoxide, titanium (triethanolamine)isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolamine, butyl titanate dimer, etc. Titanium oxide and composite oxides containing titanium and silicon are also preferably used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium bis(ammonium lactate) dihydroxide, polyhydroxytitanium stearate, titanium lactate, butyl titanate dimer, titanium oxide, titania / silica composite oxide (e.g., Acordis Industrial Preferred are tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, and titania / silica composite oxide (for example, product name C-94 manufactured by Acordis Industrial Fibers).

[0052] Specific examples of zirconium compounds include zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris(butoxy)stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, potassium zirconium oxalate, polyhydroxyzirconium stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate, and mixtures thereof. Zirconium oxide and composite oxides containing, for example, zirconium and silicon may also be used. Among these, zirconyl diacetate, zirconium tris(butoxy)stearate, zirconium tetraacetate, zirconium acetate hydroxide, ammonium zirconium oxalate, potassium zirconium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, and zirconium tetra-t-butoxide are preferred.

[0053] Specific examples of germanium compounds include inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. From the viewpoints of cost and availability, germanium oxide, tetraethoxygermanium, and tetrabutoxygermanium are preferred, with germanium oxide being particularly preferred.

[0054] When a metal compound is used as a polymerization catalyst, the amount of catalyst used, expressed as the amount of metal relative to the polyester produced, is usually 5 ppm or more, preferably 10 ppm or more, and the upper limit is usually 30,000 ppm or less, preferably 1,000 ppm or less, more preferably 250 ppm or less, and particularly preferably 130 ppm or less. If the amount of catalyst used is too large, not only is it economically disadvantageous but the thermal stability of the polymer is reduced, while if the amount is too small, the polymerization activity is reduced, which makes it more likely that the polymer will decompose during polymer production. As for the amount of catalyst used here, the method of reducing the amount of catalyst used is a preferred embodiment, because the amount of terminal carboxyl groups in the polyester produced is reduced as the amount of catalyst used is reduced.

[0055] The reaction temperature for the esterification reaction and / or transesterification reaction between diol units and dicarboxylic acid units is usually in the range of 150°C to 260°C, and the reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. The reaction pressure is usually normal pressure to 10 kPa, and the reaction time is usually 1 hour to 10 hours.

[0056] In the above-mentioned production process, a chain extender (coupling agent) may be added to the reaction system. After the polycondensation is completed, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and reacted with the polyester obtained by polycondensation.

[0057] High-molecular-weight polyesters using these chain extenders (coupling agents) can be produced using known techniques. After polycondensation is complete, the chain extender is added to the reaction system in a homogeneous, molten state without a solvent and reacted with the polyester obtained by polycondensation. Specifically, a polyester with a higher molecular weight can be obtained by reacting the chain extender with a polyester prepolymer obtained by catalytically reacting a diol with a dicarboxylic acid, which has substantially hydroxyl end groups and a mass-average molecular weight (Mw) of 20,000 or more, preferably 40,000 or more. A prepolymer with a mass-average molecular weight of 20,000 or more can be produced with the use of a small amount of coupling agent without being affected by residual catalyst, even under harsh conditions such as a molten state, and therefore without forming gel during the reaction.

[0058] [Polyester film] The polyester film according to the present disclosure is a film containing the above-described polyester, i.e., a film containing a polyester using ethylene glycol derived from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide (hereinafter also referred to as a "gas-derived polyester"). From the viewpoint of reducing the environmental load, the content of the gas-derived polyester in the polyester film is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 95% by mass or more. The content of the gas-derived polyester in the polyester film is 100% by mass or less, practically 99% by mass or less, and more practically 97% by mass or less.

[0059] Since the polyester film according to the present disclosure contains a gas-derived polyester, the content of carbon dioxide molecules in the polyester film tends to be higher than that of films using conventional fossil fuel-derived polyester. For example, the content of carbon dioxide molecules in the polyester film according to the present disclosure is 1.1 × 10 18 It is preferable that the number of particles is 1.5×10 18More preferably, it is 2.0 × 10 18 The content of carbon dioxide molecules in the polyester film according to the present disclosure is more preferably 3.0 × 10 18 It is preferable that the number of particles is less than 2.7 × 10 18 It is more preferable that the number of particles is 2.4×10 18 It is more preferable that the number is not more than 1 / g. The content of carbon dioxide molecules in the polyester film is measured by thermal desorption spectrometry-mass spectrometry (TDS-MS), specifically by the method described in the examples below.

[0060] Furthermore, the content of water molecules in the polyester film according to the present disclosure tends to be higher than that in films using conventional polyesters derived from fossil fuels. For example, the content of water molecules in the polyester film according to the present disclosure is 8.6×10 19 It is preferable that the number of particles is 9.0 × 10 19 More preferably, it is 1.0 × 10 20 The content of water molecules in the polyester film according to the present disclosure is more preferably 2.5×10 20 It is preferable that the number of particles is less than 2.0 × 10 20 It is more preferable that the number of particles is less than 1.5 × 10 20 It is more preferable that the number is not more than 1 / g. The content of water molecules in the polyester film is measured by thermal desorption spectrometry-mass spectrometry (TDS-MS), specifically by the method described in the Examples below.

[0061] The polyester film may contain various additives as long as the properties of the present disclosure are not impaired. Examples of additives include plasticizers, UV stabilizers, color inhibitors, matting agents, deodorizers, flame retardants, weather resistance agents, antistatic agents, thread friction reducers, release agents, antioxidants, ion exchange agents, and color pigments. The content of these additives is, for example, 5% by mass or more and 50% by mass or less.

[0062] To obtain the polyester film of the present disclosure by processing polyester into a film shape, a conventional method for forming a film from polyester can be used. Specifically, gas-derived polyester pellets are dried and then fed into a melt extruder heated to a temperature above the melting point (Tm) of the pellets and below Tm + 70°C. The pellets are melted and extruded into a sheet through a die such as a T-die. The extruded sheet is then rapidly cooled and solidified on a rotating cooling drum or the like to form a polyester film 10 as shown in Figure 1. The polyester film 10 obtained in this manner is composed of a single layer. As the melt extruder, a single screw extruder, a twin screw extruder, a vent extruder, a tandem extruder, etc. can be used depending on the purpose.

[0063] The polyester film according to the present disclosure is preferably biaxially stretched. The biaxial stretching can be carried out by a conventionally known method, and may be sequential biaxial stretching or simultaneous biaxial stretching. Sequential biaxial stretching and simultaneous biaxial stretching will be described below.

[0064] [Sequential biaxial stretching] In the sequential biaxial stretching, the film extruded onto the cooling drum as described above is stretched in the machine direction, and then the film is stretched in the transverse direction. The longitudinal stretching is usually performed by varying the peripheral speed of rolls, and may be performed in one step or in multiple steps using multiple pairs of rolls. The longitudinal stretching ratio is preferably 2.0 times or more, more preferably 2.5 times or more, and preferably 15.0 times or less, more preferably 7.0 times or less, even more preferably 5.0 times or less, and even more preferably 4.2 times or less. This can suppress variations in optical properties such as in-plane retardation. The stretching temperature is preferably 50° C. or higher, more preferably 80° C. or higher, and even more preferably 95° C. or higher, and is preferably 120° C. or lower, more preferably 115° C. or lower, and even more preferably 110° C. or lower, thereby making it possible to suppress variations in optical properties such as in-plane retardation.

[0065] The transverse stretching is usually performed using a tenter method, in which the film is conveyed while being held at both ends with clips, and stretched in the transverse direction. The stretching ratio in the transverse direction is preferably 2 times or more, more preferably 2.5 times or more, and is preferably 15 times or less, more preferably 5 times or less. This can suppress variations in optical properties such as in-plane retardation. The stretching temperature is preferably 50° C. or higher, more preferably 90° C. or higher, and even more preferably 95° C. or higher, and is preferably 120° C. or lower, more preferably 110° C. or lower, and even more preferably 105° C. or lower, thereby making it possible to suppress variations in optical properties such as in-plane retardation.

[0066] The film sequentially biaxially stretched as described above is preferably heat-treated in a tenter at a temperature equal to or higher than the stretching temperature and lower than the melting point to impart flatness and dimensional stability. Specifically, heat setting is preferably carried out at a temperature of 120°C or higher, more preferably 190°C or higher, and preferably 235°C or lower, more preferably 225°C or lower. Furthermore, from the viewpoint of suppressing variations in optical properties such as in-plane retardation, it is preferable to perform post-heat treatment stretching of 1% to 10% in the first half of the heat treatment. This can suppress variations in optical properties such as in-plane retardation. After the heat treatment, the film is slowly cooled to room temperature and then wound up. If necessary, a relaxation treatment or the like may be performed during the heat treatment or slow cooling. The relaxation rate during the heat treatment is preferably 0.5% or more, more preferably 0.8% or more, even more preferably 1% or more, and preferably 5% or less, more preferably 3% or less, even more preferably 2.5% or less, and even more preferably 2% or less. This can suppress variations in optical properties such as in-plane retardation. The relaxation rate during slow cooling is preferably 0.5% or more, and preferably 3% or less, more preferably 2% or less, even more preferably 1.5% or less, and even more preferably 1.0% or less. This can suppress variations in optical properties such as in-plane retardation. From the viewpoint of flatness, the temperature during slow cooling is preferably 80°C or more, more preferably 90°C or more, and even more preferably 100°C or more, and preferably 150°C or less, more preferably 130°C or less, and even more preferably 120°C or less.

[0067] [Simultaneous biaxial stretching] In simultaneous biaxial stretching, the film extruded onto the cooling drum as described above is introduced into a simultaneous biaxial tenter, and while both ends of the film are held with clips, the film is conveyed and stretched simultaneously and / or stepwise in the machine and cross directions. Simultaneous biaxial stretching machines include pantograph, screw, drive motor, and linear motor types, but drive motor and linear motor types are preferred, as they allow the stretching ratio to be changed as desired and relaxation treatment to be performed at any desired location.

[0068] The area ratio of the simultaneous biaxial stretching is preferably 2 times or more, more preferably 3 times or more, even more preferably 6 times or more, even more preferably 10 times or more, and is preferably 50 times or less, more preferably 30 times or less, even more preferably 25 times or less, even more preferably 20 times or less, and particularly preferably 15 times or less, thereby making it possible to suppress variations in optical properties such as in-plane retardation. In the case of simultaneous biaxial stretching, it is preferable to make the stretching ratios in the machine direction and the cross direction the same and to make the stretching speeds approximately equal in order to suppress in-plane orientation differences.

[0069] The stretching temperature for simultaneous biaxial stretching is preferably 50° C. or higher, more preferably 90° C. or higher, and even more preferably 100° C. or higher, and is preferably 160° C. or lower, more preferably 150° C. or lower, and even more preferably 140° C. or lower, thereby making it possible to suppress variations in optical properties such as in-plane retardation.

[0070] The simultaneously biaxially stretched film is preferably subsequently heat-treated in a heat-setting chamber in a tenter at a temperature equal to or higher than the stretching temperature and lower than the melting point in order to impart flatness and dimensional stability. The heat-treatment conditions are the same as those after the successive biaxial stretching.

[0071] The thickness of the polyester film is optional depending on the application, but is usually 5 μm or more and 500 μm or less. The breaking strength of such a film is 1 kg / mm ​​in the MD direction. 2More than 40kg / mm 2 Below, 1kg / mm ​​in the TD direction 2 More than 35kg / mm 2 The elongation at break is 10% or more and 350% or less in the MD direction and 3% or more and 300% or less in the TD direction. Thus, the polyester film according to the present disclosure has physical properties equivalent to those of polyester films produced from conventional fossil fuel-derived materials or biomass-derived materials.

[0072] Although the polyester film 10 shown in FIG. 1 is composed of a single layer, the polyester film of the present disclosure is not limited to a single layer configuration and may be composed of multiple layers. When the polyester film of the present disclosure is composed of multiple layers, at least one layer must contain a gas-derived polyester, and the other layers may not contain a gas-derived polyester. Examples of polyesters constituting layers that do not contain a gas-derived polyester include at least one selected from the group consisting of fossil fuel-derived polyesters, biomass-derived polyesters, and recycled polyesters. Recycled polyester refers to polyesters recycled by collecting used products such as containers shipped to the market.

[0073] The polyester film according to the present disclosure can be subjected to secondary processing for the purpose of imparting surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubrication functions, optical functions, thermal functions, biocompatibility, etc. Examples of secondary processing include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.), etc.

[0074] The refractive index and transmittance of the polyester film according to the present disclosure are equivalent to those of polyester films produced from conventional fossil fuel-derived materials or biomass-derived materials. Therefore, suitable applications of the polyester film according to the present disclosure include, for example, optical applications (optical film applications, polarizing plate applications, and display device applications). In particular, the polyester film according to the present disclosure can be suitably used as a substrate for an optical film for an image display device, a substrate for a touch panel for an image display device, or the like. For example, an optical film using a polyester film according to the present disclosure as a substrate is an optical film according to the present disclosure. The optical film according to the present disclosure comprises a polyester film according to the present disclosure.

[0075] Furthermore, the polyester film according to the present disclosure can be suitably used for applications such as laminates, packaging, various label materials, lid materials, sheet molded products, laminated tubes, etc. Hereinafter, laminates, packaging, stand-up pouches, lid materials, tube containers, liquid paper containers, and paper cups will be described as examples of applications of the polyester film according to the present disclosure.

[0076] [Laminate] A laminate according to the present disclosure includes a polyester film according to the present disclosure. For example, the laminate according to the present disclosure includes a polyester film according to the present disclosure and a sealant layer provided on one or both surfaces of the polyester film according to the present disclosure. FIG. 2 is a cross-sectional view illustrating a simplified example of the configuration of a laminate according to the present disclosure. As shown in FIG. 2, a laminate 20A includes a polyester film 10 and a sealant layer 21, with the sealant layer 21 laminated above the polyester film 10. In the embodiment shown in FIG. 2, the laminate 20A is configured such that the sealant layer 21 is laminated above the surface of the polyester film 10. However, the laminate 20A may also be configured such that the sealant layer 21 is laminated below the surface of the polyester film 10, or such that the sealant layer 21 is laminated on both the upper and lower surfaces of the surface of the polyester film 10.

[0077] Furthermore, the laminate 20A may have at least one other layer, such as a barrier layer, a support, a resin layer, or a printed layer, above and / or below the surface of the polyester film 10, in addition to the sealant layer 21. The other layers will be described later.

[0078] The sealant layer 21 is provided above the polyester film 10 of the laminate 20A, for example, as shown in Fig. 2. The sealant layer 21 is a layer formed of a film of a heat-sealable resin that can be fused together by heat.

[0079] The material for forming the sealant layer 21 is not particularly limited as long as it is a resin that can be fused to each other by heat, and examples thereof include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), ethylene-α-olefin copolymer polymerized using a metallocene catalyst, ethylene-polypropylene random or block copolymer, polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene Examples of suitable resins include polyolefin resins such as ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer (EMMA), ionomer resins, heat-sealable ethylene-vinyl alcohol resins, ethylene-propylene copolymers, methylpentene polymers, polybutene polymers, and cyclic olefin copolymers; acid-modified polyolefin resins obtained by modifying polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid; polyvinyl acetate resins, poly(meth)acrylic resins, and polyvinyl chloride resins. These may be used alone or in combination. The sealant layer 21 can be a film or sheet of any of the above resins, or a coating film thereof.

[0080] When polyethylene is used as the material for forming the sealant layer 21, in addition to ethylene obtained from fossil fuels, polymerized ethylene derived from biomass may also be used as the raw material. Examples of biomass-derived ethylene that can be used include those described in JP 2012-251006 A. By using polyethylene obtained by polymerizing biomass-derived ethylene as the material for forming the sealant layer 21, a layer made of a carbon-neutral material can be formed. Therefore, by using polyethylene in combination with the gas-derived polyester described above, the amount of fossil fuel used can be further significantly reduced, thereby reducing the environmental impact.

[0081] As the polyethylene obtained by polymerizing biomass-derived ethylene, a commercially available product may be used, for example, a sugarcane-derived linear low-density polyethylene resin "C4LL-LL118 (d=0.916, MFR=1.0 g / 10 min)" manufactured by Braskem.

[0082] 2, the laminate 20A has one sealant layer 21, but may have two or more sealant layers 21. When there are two or more sealant layers 21, the sealant layers 21 may have the same composition or different compositions.

[0083] The thickness of the sealant layer 21 is preferably 20 μm or more, more preferably 30 μm or more, and is preferably 200 μm or less, more preferably 130 μm or less.

[0084] Examples of methods for laminating the sealant layer 21 on the upper surface (inner surface) of the laminate 20A include dry lamination and melt extrusion lamination. Furthermore, when performing the lamination, the film may be subjected to pretreatment such as corona treatment, ozone treatment, and flame treatment, as needed. Among these, dry lamination is more preferred due to its excellent adhesive strength.

[0085] 2 includes the polyester film 10 and the sealant layer 21, the laminate 20A is not limited thereto, and as long as it includes these layers, the laminate 20A may include at least one other layer in addition to the polyester film 10 and the sealant layer 21. For example, the laminate 20A may include other layers between the polyester film 10 and the sealant layer 21, on the surface of the sealant layer 21 opposite to the surface on which the polyester film 10 is laminated, or on the surface of the polyester film 10 opposite to the surface on which the sealant layer 21 is laminated, depending on the application of the laminate.

[0086] Examples of other layers include a barrier layer, a support, a resin layer, and a printed layer. When two or more other layers are included, the other layers may have the same composition or different compositions. These other layers can be laminated to each other via an adhesive layer by dry lamination or via an adhesive resin layer by melt extrusion lamination.

[0087] The barrier layer functions as a gas barrier layer that prevents the permeation of gases such as oxygen gas, or a water vapor barrier layer that prevents the permeation of water vapor. Examples of barrier layers that can be used include a layer made of a metal foil obtained by rolling a metal such as aluminum foil, a layer made of a vapor-deposited film of a metal such as aluminum, a layer made of a vapor-deposited film of an inorganic oxide such as alumina, a layer made of a gas barrier coating film, and a saponified ethylene-vinyl acetate copolymer (EVOH). When the barrier layer is formed of a layer made of a vapor-deposited film of an inorganic oxide such as alumina, a layer made of the gas barrier coating film may be provided on at least one side of the layer made of a vapor-deposited film of an inorganic oxide to impart or improve gas barrier properties. The barrier layer can be formed by a conventionally known method, and its composition and formation method are not particularly limited. Examples of metal foils and vapor-deposited films that can be used for the barrier layer include those described in JP 2012-96469 A. The gas barrier coating film contains one or more alkoxides and a polyvinyl alcohol resin and / or an ethylene-vinyl alcohol copolymer, and is obtained by polycondensation using a sol-gel method. For example, the one described in JP 2012-96469 A can be used. As the EVOH constituting the barrier layer, for example, the one described in JP 2008-307847 A can be used. Two or more barrier layers may be provided. When two or more barrier layers are provided, they may have the same composition or different compositions. Furthermore, one or more barrier layers may be provided on each side of the polyester film 10.

[0088] The support is not particularly limited and can be formed using any known material, such as an oriented polyester resin layer, an oriented polyamide resin layer, an oriented polyolefin resin layer, or a paper layer (paper substrate), as long as it can support the laminate and improve the strength characteristics and impact resistance of the laminate. Furthermore, a biomass-derived material may also be used as the support. Furthermore, the support can be formed using one of these layers alone or in combination of two or more layers.

[0089] The polyester-based resin layer that can be used as the support can be a conventionally known polyester derived from fossil fuels or a polyester derived from biomass. The polyester-based resin layer may also be a layer formed by mixing a resin material containing a conventional raw material derived from fossil fuels with a resin material containing a raw material derived from biomass.

[0090] To improve adhesion, a dicarboxylic acid component containing a sulfonic acid group may be used. Examples of sulfonic acid group-containing dicarboxylic acids include metal sulfonate-containing dicarboxylic acids. Examples of metal sulfonate-containing dicarboxylic acids include metal salts (alkali metal salts, alkaline earth metal salts, etc.) of sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5-[4-sulfophenoxy]isophthalic acid. In particular, from the viewpoint of achieving good adhesion and deformation resistance, it is preferable to use sodium sulfoterephthalic acid or 5-sodium sulfoisophthalic acid. In the sulfone group-containing polyester, the copolymerization ratio of the sulfonic acid group-containing dicarboxylic acid is preferably 0.5 mol % or more and 10 mol % or less based on the total acid components. Furthermore, the intrinsic viscosity is preferably 0.3 dL / g or more and 0.8 dL / g or less.

[0091] Depending on the application of the package including the laminate according to the present disclosure, various polyester-based resins can be used for the polyester-based resin layer, and a mixture of two or more types may also be used. For example, when polyester is used, a support having excellent thermal dimensional stability, aroma retention, and heat resistance can be obtained. Furthermore, when a sulfonic acid group-containing polyester is used, a coextruded film having high interlayer adhesive strength can be obtained.

[0092] The polyester resin layer may contain various additives such as a lubricant, if necessary.

[0093] The polyamide-based resin layer usable as the support may be primarily made of aliphatic polyamide, but may also contain other polyamide components, such as aromatic polyamides. Examples of aliphatic polyamides that can be used include aliphatic polyamides obtained by polycondensation of aliphatic or alicyclic diamines such as hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or 1,4-bis(aminomethyl)cyclohexane, and bis(p-aminocyclohexylmethane) with dicarboxylic acids or derivatives thereof such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid; polyamide resins obtained by condensation of ε-aminocaproic acid, 11-aminoundecanoic acid, and the like; polyamide resins obtained from lactam compounds such as ε-caprolactam and ω-laurolactam; and mixtures thereof. Specifically, aliphatic polyamide resins such as nylon 6, nylon 6,6, nylon 9, nylon 11, nylon 12, nylon 6 / 66, nylon 66 / 610, nylon MXD6, etc. Among them, suitable aliphatic polyamides include nylon 6, nylon 6,6, nylon-6 / 6,6, etc. Examples of two or more aliphatic polyamides include a combination of nylon 6 and nylon 6 / 6,6 in any ratio.

[0094] Examples of stretched polyolefin resin layers that can be used as the support include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), ethylene-α-olefin copolymers polymerized using a metallocene catalyst, and random or block copolymers of ethylene and polypropylene.

[0095] When a polyester resin layer or a polyamide resin layer is used as the support, a modified polyolefin resin layer made of modified polyolefin may be provided between the support and the sealant layer 21 in order to improve the adhesion between the support and the sealant layer 21. Modified polyolefin is a polyolefin resin modified by substituting part of the polyolefin, which is the main component, with another substance (monomer) by copolymerization or co-condensation, or by locally reacting an appropriate substance (monomer). Examples of such resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), ethylene-α-olefin copolymers polymerized using a metallocene catalyst, polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ionomer resins, ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-propylene copolymer, methylpentene polymer, polyethylene, polyethylene-based resins, and acid-modified polyolefin-based resins such as polyolefin-based resins modified with acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, or other unsaturated carboxylic acids. It goes without saying that the above-mentioned polyethylene-based resins can also be those using the above-mentioned biomass-derived ethylene as a monomer unit.

[0096] Preferred modified polyolefins are copolymers having a structure in which polyolefin segments and polar non-olefin segments are bonded in a block, graft, and / or random manner, such as copolymers of propylene-based polyolefin segments and segments containing lactic acid as constituent components, copolymers of ethylene-based polyolefin segments and segments containing acrylic acid units as constituent components, copolymers of propylene-based polyolefin segments and segments containing acrylic acid units as constituent components, etc. Specifically, examples of maleic anhydride-modified polyolefin resins that can be used include Admer SE800, SF740, SF731, and SF730 manufactured by Mitsui Chemicals, Inc.

[0097] In addition to the above, commercially available polylactic acid films may also be used as biomass-derived materials for the support. For example, polylactic acid films sold by Mitsui Chemicals Tohcello Co., Ltd. can be suitably used.

[0098] Furthermore, as a paper layer (paper substrate) that can be used as a support, any paper can be used depending on the desired rigidity, etc., and known papers such as high-quality paper, construction paper, art paper, coated paper, pure white roll paper, kraft paper, label paper with enhanced water resistance, paperboard such as cup base paper, card paper, ivory paper, and manila cardboard, milk carton base paper, cup base paper, synthetic paper, and clay-coated paper can be used.

[0099] The thickness of the polyester resin layer or the like serving as a support may be adjusted appropriately depending on the intended use of the laminate. For example, when the laminate is used as a packaging material for an application requiring rigidity, a thick support can be used.

[0100] Furthermore, by forming the support using a resin material containing biomass-derived raw materials, the support becomes a layer made of a carbon-neutral resin. By forming a laminate with the polyester film 10 and a support having a layer made of a carbon-neutral resin, it is possible to manufacture a laminate having two or more layers containing a carbon-neutral resin. This allows for a significant reduction in the amount of fossil fuel used to form the support, thereby reducing the environmental impact.

[0101] The method for forming the support is not particularly limited and may be a conventionally known method. The support may be formed by extrusion lamination of these materials, or may be formed in advance as a film by a T-die method, an inflation method, or the like, and then laminated on the printing layer by dry lamination, or the like.

[0102] A printing layer can be provided as needed, for example, between the polyester film 10 and the support. The printing layer is a layer on which any printed pattern such as letters, pictures, figures, symbols, designs, etc. is formed for decoration, indication of contents, expiration date, manufacturer, seller, etc. The printing layer may be provided on the entire surface or on a part of the surface.

[0103] The printing layer can be formed using conventionally known pigments or dyes, and an ink composition can be used which contains one or more ordinary ink vehicles as the main component, optionally containing one or more additives such as plasticizers, stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, curing agents, crosslinking agents, lubricants, antistatic agents, and fillers as needed, and further containing a colorant such as a dye or pigment, and which is thoroughly kneaded with a solvent, diluent, etc.

[0104] The ink vehicle may be one or more of known ones, such as linseed oil, tung oil, soybean oil, hydrocarbon oil, rosin, rosin ester, rosin-modified resin, shellac, alkyd resin, phenolic resin, maleic acid resin, natural resin, hydrocarbon resin, polyvinyl chloride resin, polyacetic acid resin, polystyrene resin, polyvinyl butyral resin, acrylic or methacrylic resin, polyamide resin, polyester resin, polyurethane resin, epoxy resin, urea resin, melamine resin, aminoalkyd resin, nitrocellulose, ethyl cellulose, chlorinated rubber, cyclized rubber, etc.

[0105] The method for forming the printed layer is not particularly limited, and can be, for example, a conventional printing method such as gravure printing, offset printing, letterpress printing, screen printing, transfer printing, flexographic printing, etc. Using such a method for forming a printed layer, the ink composition can be printed onto the outer surface side of the support in a desired pattern to form a printed layer.

[0106] The thickness of the printed layer is preferably 0.1 μm or more, more preferably 0.3 μm or more, and is preferably 8 μm or less, more preferably 5 μm or less.

[0107] The printing layer is preferably formed after a surface treatment has been previously performed on the side of the support on which the printing layer is to be formed. Such surface treatments include pretreatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals. Alternatively, the surface may be treated in advance by optionally applying a primer coating agent, undercoating agent, anchor coating agent, or the like.

[0108] The adhesive layer used when bonding two layers by dry lamination can be formed by applying an adhesive used for lamination (laminating adhesive) to the surface of the layer to be laminated and drying it. Examples of laminating adhesives that can be used include one-component or two-component curing or non-curing vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, and rubber adhesives, including solvent-based, water-based, and emulsion-based adhesives. The laminating adhesive can be applied to the coating surface of the layer constituting the laminate by, for example, direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fountain coating, transfer roll coating, or other methods. The thickness of the adhesive layer is preferably 0.5 μm or more, more preferably 1 μm or more. This ensures sufficient adhesive strength. Furthermore, the thickness of the adhesive layer is preferably 10 μm or less, more preferably 5 μm or less. This reduces the likelihood of misalignment during lamination.

[0109] The adhesive resin layer provided when bonding two layers by melt extrusion lamination is formed by melt extrusion lamination using a thermoplastic resin. The thermoplastic resin that can be used for the adhesive resin layer is a polyethylene resin, a polypropylene resin, a cyclic polyolefin resin, or a copolymer resin, modified resin, or mixture (including alloy) containing these resins as the main component. Examples of polyolefin resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), ethylene-α-olefin copolymers polymerized using a metallocene catalyst, random or block copolymers of ethylene and polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-maleic acid copolymer, and ionomer resins. To improve interlayer adhesion, acid-modified polyolefin resins obtained by modifying the above polyolefin resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid can also be used. Furthermore, resins obtained by graft-polymerizing or copolymerizing unsaturated carboxylic acids, unsaturated carboxylic anhydrides, and ester monomers onto polyolefin resins can also be used. These materials can be used alone or in combination of two or more. Examples of cyclic polyolefin-based resins that can be used include cyclic polyolefins such as ethylene-propylene copolymers, polymethylpentene, polybutene, and polynorbornene. These resins can be used alone or in combination of two or more. It goes without saying that the polyethylene-based resins mentioned above can be those that use the above-mentioned biomass-derived ethylene as a monomer unit.

[0110] Various plastic compounding agents and additives can be added to the adhesive resin layer as needed, for example, to improve or modify the film's processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, release properties, flame retardancy, mildew resistance, electrical properties, strength, etc., and the amount added can be any amount ranging from a trace amount to several tens of percent depending on the purpose. Common additives that can be used in the above include, for example, lubricants, plasticizers, fillers, antistatic agents, antiblocking agents, crosslinking agents, antioxidants, UV absorbers, light stabilizers, colorants (dyes, pigments, etc.), and even modifying resins can be used.

[0111] The thickness of the adhesive resin layer can be set appropriately, and is preferably 5 μm or more, more preferably 10 μm or more, and is preferably 800 μm or less, more preferably 500 μm or less. If the thickness is less than the lower limit, the moisture barrier properties will be insufficient, and if it is more than the upper limit, the quality will be excessive and moldability will also be reduced. The adhesive resin layer may have a single layer structure or a multi-layer structure.

[0112] In addition, when a polyolefin resin having a polar group, such as the acid-modified polyolefin resin described above, is used as the adhesive resin layer and the adhesive resin layer is laminated on the polyester film 10 by the melt extrusion lamination method, the adhesive resin layer can be laminated without performing surface treatment such as an anchor coating agent.

[0113] Furthermore, one or both surfaces of the laminate may be subjected to secondary processing for the purpose of imparting surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubrication functions, optical functions, thermal functions, biocompatibility, etc. Examples of secondary processing include embossing, painting, bonding, printing, metallizing (plating, etc.), machining, surface treatments (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.), etc. Furthermore, the laminate may be subjected to lamination (dry lamination or extrusion lamination), bag making, and other post-processing processes to produce packages, etc.

[0114] As described above, the laminate 20A is a film comprising a polyester film 10 and a sealant layer 21, and since the polyester film 10 is formed from a layer made of a carbon-neutral material and has excellent hygiene, by using the polyester film 10 in the laminate 20A, it is possible to reduce the amount of fossil fuel used for the laminate 20A as a whole, thereby realizing a laminate that is highly effective in reducing CO2 emissions and has excellent hygiene.

[0115] <Package> As described above, laminates including polyester films according to the present disclosure reduce fossil fuel consumption, have a significant effect on CO2 emissions, and are highly hygienic. Therefore, they are useful as packaging materials for foods and the like, and can be suitably used, for example, as packaging films for packages. Examples of packaging materials include packaging bags, lids, laminated tubes, liquid containers, paper cups, and various label materials. Examples of packaging bags include various types of packaging bags, such as stand-up pouches, side-sealed bags, two-sided sealed bags, three-sided sealed bags, four-sided sealed bags, envelope-sealed bags, palm-sealed bags (pillow-sealed bags), pleated sealed bags, flat-bottom sealed bags, square-bottom sealed bags, and gusset-sealed bags. The thickness of the laminate can be determined appropriately depending on the application, and is preferably 30 μm or more, more preferably 35 μm or more, and preferably 300 μm or less, more preferably 180 μm or less. An example of a package using a laminate including a polyester film according to the present disclosure is described below. In this disclosure, each layer of the packaging body exemplified below, other than the sealant layer 21, is a single layer, but this is not limited to this and may have two or more layers. Also, while the packaging body exemplified below has a printed layer, this is not limited to this and may not have a printed layer.

[0116] [Standing pouch] A case will be described in which a laminate including a polyester film according to the present disclosure is applied to a stand-up pouch. FIG. 3 is a perspective view showing a simplified example of a stand-up pouch. As shown in FIG. 3, the stand-up pouch 30 is composed of two side sheets 31 and one bottom sheet 32. In the stand-up pouch 30, the side sheets 31 and the bottom sheet 32 ​​are composed of separate members. The stand-up pouch 30 is a package formed by bag-making such that the sealant layer of the laminate constituting the side sheet 31 is the innermost layer. In the present disclosure, the side sheets 31 and the bottom sheet 32 ​​of the stand-up pouch 30 are composed of separate members, but this is not limited thereto, and the side sheets 31 and the bottom sheet 32 ​​may be composed of the same member.

[0117] The side sheet 31 can be formed using a laminate including a polyester film according to the present disclosure. FIG. 4 is a cross-sectional view showing a simplified example of the configuration of a laminate forming the side sheet 31. As shown in FIG. 4, the laminate 20B forming the side sheet 31 can include, for example, a sealant layer 21, a support 33, a printed layer 34, and a polyester film 10, and can be constructed by laminating the sealant layer 21, the support 33, the printed layer 34, and the polyester film 10 in this order from the inner surface to the outer surface. The standing pouch 30 is produced by heat-sealing and bonding the sealant layers 21 of the side sheet 31 together. The laminate 20B may also include the barrier layer between any of the layers forming the laminate 20B, such as between the polyester film 10 and the printed layer 34.

[0118] In this embodiment, the printed layer 34 is provided between the polyester film 10 and the support 33, but if the support 33 is transparent, the printed layer 34 may be provided between the sealant layer 21 and the support 33.

[0119] Furthermore, in this embodiment, the side sheets 31 are formed using a laminate comprising a polyester film according to the present disclosure, but this is not limited to this, and the bottom sheet 32 ​​may be formed using a laminate comprising a polyester film according to the present disclosure, or both the side sheets 31 and the bottom sheet 32 ​​may be formed using laminates comprising a polyester film according to the present disclosure.

[0120] Furthermore, the laminate 20B forming the side sheet 31 is not limited to the layer structure shown in Fig. 4, but may have the layer structure shown in Fig. 2, or may have other layers as described above. Furthermore, depending on the material constituting the support 33, the positions of the layers may be changed as appropriate. For example, as shown in Fig. 5, the laminate 20C forming the side sheet 31 may have a layer structure in which the sealant layer 21, polyester film 10, support 33, and printed layer 34 are laminated in this order from the inner surface to the outer surface. Furthermore, the laminate 20C may also have the above-mentioned barrier layer between any of the layers constituting the laminate 20C, such as between the polyester film 10 and the sealant layer 21.

[0121] The standing pouch 30 can be manufactured using a conventionally known manufacturing method, for example, by stacking two side sheets 31 facing each other so that the sealant layer 21 is the innermost layer, inserting a bottom sheet 32 ​​between the two side sheets 31, and heat-sealing the side sheet 31 and the bottom sheet 32.

[0122] Heat sealing can be performed by any known method, such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, or ultrasonic sealing.

[0123] The standing pouch 30 can be suitably used as a packaging bag for filling liquids, for packaging chemical products, pharmaceuticals, quasi-drugs, cosmetics, food, etc., for example, as an outer bag for patches, or as a standing pouch used for refill contents of liquid detergent, liquid fabric softener, liquid soap, etc.

[0124] Depending on the heat-sealing configuration of the laminate, various packaging bags other than stand-up pouches can be produced. Fig. 6 is a simplified front view of an example of a pillow bag, Fig. 7 is a simplified front view of an example of a three-sided sealed bag, and Fig. 8 is a simplified front view of an example of a four-sided sealed bag. In Figs. 6 to 8, heat-sealed locations are indicated by hatching. The pillow bag 41 shown in Fig. 6 can be obtained by forming a bag with the sealant layer 21 of the laminates 20A to 20C shown in Figs. 2, 4, and 5 as the innermost layer, and then heat-sealing and bonding two opposing sides of the laminate. The three-sided sealed bag 42 shown in Fig. 7 can be obtained by forming a bag with the sealant layer 21 of the laminates 20A to 20C as shown in Figs. 2, 4, and 5 as the innermost layer, and then heat-sealing and bonding three sides of the laminates 20A to 20C. Furthermore, the four-sided sealed bag 43 shown in Figure 8 can be obtained by making a bag so that the sealant layer 21 of the laminates 20A to 20C as shown in Figures 2, 4 and 5 is the innermost layer, and then heat-sealing and bonding the four sides of the laminates 20A to 20C.

[0125] [Lid material] Next, a case where a lid material is formed using a laminate including a polyester film according to the present disclosure will be described. The lid material is a case where the support 33 constituting the laminate is made of a paper layer, and can be formed using laminates 20A to 20C having layer configurations as shown in Figures 2, 4, and 5.

[0126] The lid material can be suitably used as a lid material for cup-shaped packaging containers, in particular for packaging containers for sealing contents such as instant foods such as cup ramen and cup yakisoba that can be eaten by pouring hot water over them, foods to be heated in a microwave oven and other ready-to-eat foods, heated beverages, beverages to be heated in a microwave oven, snacks, confectionery, jellies, etc.

[0127] [Tube container] Next, a case where a tube container is formed using a laminate including a polyester film according to the present disclosure will be described. Fig. 9 is a partial cross-sectional view showing a simplified example of a tube container. As shown in Fig. 9, a tube container 50 includes a head portion 51 and a cylindrical body portion 52.

[0128] The head portion 51 is composed of a hollow conical shoulder portion 53 and a spout portion 54, which are integrally formed.

[0129] The cylindrical body 52 is connected to a shoulder 53 of the head 51. The cylindrical body 52 can be formed using a laminate. FIG. 10 is a cross-sectional view showing a simplified example of the configuration of a laminate forming the cylindrical body of a tube container. As shown in FIG. 10, the laminate 20D forming the cylindrical body 52 includes a first sealant layer 21A, a polyester film 10, a printed layer 34, and a second sealant layer 21B, and is configured by laminating the first sealant layer 21A, the polyester film 10, the printed layer 34, and the second sealant layer 21B in this order from the inner surface to the outer surface of the cylindrical body 52. ​​The laminate 20D may also include the above-mentioned barrier layer between any of the layers forming the laminate 20D, such as between the polyester film 10 and the printed layer 34.

[0130] Furthermore, the layer structure of the laminate 20D forming the tubular body 52 is not limited to that shown in FIG. 10 , and the layer structure of the laminate 20D can be adjusted as appropriate. Another example of the layer structure of the laminate forming the tubular body 52 is shown in FIG. 11 . As shown in FIG. 11 , the laminate 20E forming the tubular body 52 is similar to the laminate 20D shown in FIG. 10 except that an adhesive resin layer 55 is provided between the polyester film 10 and the printed layer 34, and a support 33 is provided between the printed layer 34 and the second sealant layer 21B. The laminate 20E may also include the barrier layer between any of the layers forming the laminate 20E, such as between the polyester film 10 and the adhesive resin layer 55.

[0131] The cylindrical body 52 is produced by overlapping the first sealant layer 21A and the second sealant layer 21B at both ends of the cylindrical body 52 and heat-sealing and fusing the overlapped portions. The cylindrical body 52 has a head 51 connected to the top of one opening. Note that the method for overlapping the both ends of the cylindrical body 52 is not limited to overlapping the first sealant layer 21A and the second sealant layer 21B, and the second sealant layers 21B may also be overlapped.

[0132] Heat sealing can be performed by a conventionally known method such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, ultrasonic sealing, or flame sealing.

[0133] An example of a manufacturing method for the tube container 50 will be described. The head 51 is connected to one opening of the cylindrical body 52 by a conventional method such as compression molding. The contents are then filled into the other open end of the cylindrical body 52 connected to the head 51, and the open end is heat-sealed to form a bottom seal 56. This allows for the tube container 50 to be filled and packaged with the contents. A cap can be attached to the spout 54 by various methods, such as screwing or fitting, depending on the shape of the spout 54.

[0134] The tube container 50 can be suitably used as a tube container for, for example, toothpaste, cosmetics, glue, mustard paste, wasabi paste, cream, paint, cartilage, medicines, and other conventionally known products.

[0135] [Liquid paper container] Next, a liquid-carrying paper container formed using a laminate including a polyester film according to the present disclosure will be described. Fig. 12 is a perspective view showing an example of a liquid-carrying paper container. As shown in Fig. 12, the liquid-carrying paper container 60 has a rectangular cylindrical body 61 including sides, a rectangular plate-shaped bottom 62, and an upper portion 63.

[0136] The upper portion 63 has a pair of opposing inclined plates 63a and a pair of folded portions 64 that are located between the inclined plates 63a and are folded between the inclined plates 63a. A gluing tab 65 is provided at the upper end of each of the pair of inclined plates 63a, and the pair of inclined plates 63a are adhered to each other by the gluing tab 65 provided at the upper end of each of the pair of inclined plates 63a. A spout may be attached to one of the pair of inclined plates 63a, and the spout may be sealed with a cap.

[0137] The liquid-carrying paper container 60 can be formed using a laminate. FIG. 13 is a cross-sectional view showing an example of the configuration of a laminate used in the liquid-carrying paper container. As shown in FIG. 13, the laminate 20F forming the liquid-carrying paper container 60 includes a first sealant layer 21A, a polyester film 10, an adhesive resin layer 55, a paper layer 66, a second sealant layer 21B, and a printed layer 34. The first sealant layer 21A, the polyester film 10, the adhesive resin layer 55, the paper layer 66, the second sealant layer 21B, and the printed layer 34 can be laminated in this order from the inner surface to the outer surface of the liquid-carrying paper container 60. The laminate 20F may also include the barrier layer between any of the layers constituting the laminate 20F, such as between the polyester film 10 and the adhesive resin layer 55. For example, the polyester film 10 may be provided with a layer made of a vapor-deposited metal film, a layer made of a vapor-deposited inorganic oxide film, and a layer made of a gas-barrier coating film.

[0138] Any paper can be used for the paper layer 66 depending on the desired rigidity, etc., and known papers such as high-quality paper, construction paper, art paper, coated paper, pure white roll paper, kraft paper, water-resistant label paper, cup base paper, card paper, ivory paper, paperboard such as manila cardboard, milk carton base paper, cup base paper, synthetic paper, clay-coated paper, etc. can be used.

[0139] Furthermore, before laminating the second sealant layer 21B on the paper layer 66, the surface of the paper layer 66 may be subjected to corona discharge treatment, flame treatment, or the like. These treatments can improve the adhesive strength between the layers. Corona discharge treatment can be performed by passing the paper layer through a corona atmosphere generated using a known corona discharge treatment device. Flame treatment can be performed by using a known flame treatment device to heat the surface of the paper layer with fire.

[0140] The liquid paper container 60 can be manufactured using the above-mentioned laminate by a conventionally known method. For example, the laminate can be made into a box to manufacture liquid paper containers 60 of various shapes, such as gable top type and brick type.

[0141] The liquid paper container 60 can be suitably used as a paper container for all types of liquids, including alcoholic beverages such as sake, shochu, and wine, dairy drinks such as milk, foods such as soft drinks like orange juice and tea, and chemical products such as car wax, shampoo, and detergent.

[0142] [Paper cups] A paper cup formed using a laminate including a polyester film according to the present disclosure will be described below. FIG. 14 is a perspective view of a paper cup with a portion cut away. As shown in FIG. 14, a paper cup 70 has a cylindrical body 72 with a flange 71 at the top and a diameter that gradually widens toward the opening, and a bottom 73 provided at the lower end (one end) of the body 72. The body 72 has a flange 71 whose upper end is rounded outward. After the contents are placed inside the paper cup 70, a lid is attached along the flange 71 of the body 72 to seal it. The lid preferably has gas barrier properties, and conventionally known lids with gas barrier properties can also be used.

[0143] The body 72 can be formed using a laminate including a polyester film according to the present disclosure. FIG. 15 is a cross-sectional view showing an example of the configuration of a laminate used in the body of a paper cup. As shown in FIG. 15, the laminate 20G forming the body 72 includes a sealant layer 21, a polyester film 10, an adhesive resin layer 55, a paper layer 66, and a printed layer 34. The sealant layer 21, the polyester film 10, the adhesive resin layer 55, the paper layer 66, and the printed layer 34 can be stacked in this order from the inner surface to the outer surface of the body 72. The laminate 20G may also include the barrier layer between any of the layers constituting the laminate 20G, such as between the polyester film 10 and the adhesive resin layer 55. For example, the polyester film 10 may be provided with a layer made of a vapor-deposited metal film, a layer made of a vapor-deposited inorganic oxide film, and a layer made of a gas barrier coating film.

[0144] The laminate 20G forming the body 72 can be, for example, a laminate obtained by laminating in this order a low-density polyethylene resin layer as the sealant layer 21, a polyester film 10, a low-density polyethylene resin layer as the adhesive resin layer 55, and a support 33. Similarly to the body 72, the bottom 73 can also be a laminate obtained by laminating in this order a low-density polyethylene resin layer as the sealant layer 21, a polyester film 10, a low-density polyethylene resin layer as the adhesive resin layer 55, and a paper layer 66.

[0145] In this embodiment, the laminate 20G has a printed layer 34 on the outer surface side of the paper layer 66, but this is not limited to this, and a sealant layer 21 may also be provided on the outer surface side of the printed layer 34 or between the paper layer 66 and the printed layer 34.

[0146] An example of a schematic manufacturing method for a paper cup is shown in Figure 16. As shown in Figure 16, a body blank 72' is cut out in a fan shape from the laminate 20G shown in Figure 15 and given a predetermined outline, and rolled into a cylindrical shape with the printed layer 34 on the outside and the printed layer 34 on the inside, and both ends 72a' are overlapped and bonded together by heat sealing. This forms a body adhesive portion 75 on the body 72.

[0147] In addition, a circular bottom blank 73' is cut out from a cup base paper (not shown), and the outer peripheral edge of the bottom blank 73' is bent downward to form a bent portion 73a'. The bottom blank 73' may also be cut out from the laminate 20G.

[0148] Next, the formed bottom blank 73' is placed under the cylindrically processed body blank 72'. The lower end of the body blank 72' is then bent so that the bent portion 73a' of the bottom blank 73' is wrapped around the lower end of the body blank 72'. While maintaining this state, the overlapping portion of the bent portion 73a' of the bottom blank 73' and the lower end of the body blank 72' are melted with hot air, and a predetermined pressure is applied to this portion to integrate them. A flange portion 71 is then formed at the upper end of the body 72, completing the paper cup 70. The laminate 20G that forms the body 72 is configured by layering the sealant layer 21, polyester film 10, adhesive resin layer 55, paper layer 66, and printed layer 34 in this order from the inner surface to the outer surface of the paper cup 70, with the printed layer 34 being positioned on the outermost side.

[0149] The paper cup 70 can be suitably used as a paper container for snacks, instant foods that can be made into a meal by pouring hot water over them, foods that can be heated in a microwave oven, other instant foods, heated drinks, drinks that can be heated in a microwave oven, etc.

[0150] In this embodiment, the case where the body portion 72 is formed by the laminated body 20G has been described, but this is not limited to this, and only the bottom portion 73, or both the body portion 72 and the bottom portion 73 may be formed by the laminated body 20G. [Example]

[0151] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0152] [Example 1] We prepared pellets (intrinsic viscosity: 0.61 dL / g) of polyethylene terephthalate (PET) using ethylene glycol derived from carbon monoxide gas as the diol unit and terephthalic acid derived from fossil fuels as the dicarboxylic acid unit. Hereinafter, these pellets will also be referred to as pellet A. After drying, pellets A were fed to an extruder, melted at 260°C, extruded into a sheet form from a T-die, and cooled and solidified by a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was held in an 88°C environment for 1 minute, and then stretched simultaneously in the machine direction and transverse direction at a stretching rate of 100 mm / min to a stretching ratio of 3.6 times in area. In this way, the polyester film of Example 1 was obtained. The thickness of the polyester film of Example 1 was 12 μm.

[0153] [Example 2] We prepared pellets (intrinsic viscosity: 0.65 dL / g) of polyethylene terephthalate (PET) using ethylene glycol derived from carbon monoxide gas as the diol unit and terephthalic acid derived from fossil fuels as the dicarboxylic acid unit. Hereinafter, these pellets will also be referred to as pellet B. A polyester film of Example 2 was obtained in the same manner as in Example 1, except that pellets B were used instead of pellets A. The polyester film of Example 2 had a thickness of 12 μm.

[0154] [Comparative Example 1] Pellets (intrinsic viscosity: 0.61 dL / g) made of polyethylene terephthalate (PET) were prepared using fossil fuel-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit. These pellets are hereinafter also referred to as pellets C. A polyester film of Comparative Example 1 was obtained in the same manner as in Example 1, except that pellets C were used instead of pellets A. The polyester film of Comparative Example 1 had a thickness of 12 μm.

[0155] Comparative Example 2 Pellets (intrinsic viscosity: 0.65 dL / g) made of polyethylene terephthalate (PET) were prepared using fossil fuel-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit. These pellets are hereinafter also referred to as pellets D. A polyester film of Comparative Example 2 was obtained in the same manner as in Example 1, except that pellet D was used instead of pellet A. The polyester film of Comparative Example 2 had a thickness of 12 μm.

[0156] [Haze measurement] Test pieces measuring 50 mm long x 50 mm wide were cut out from each of the polyester films of Examples 1 and 2 and Comparative Examples 1 and 2. The haze of each test piece was measured using a haze meter (NDH4000, manufactured by Nippon Denshoku Industries Co., Ltd.) under an environment of a temperature of 23°C and a relative humidity of 50% RH. The measurement was performed in accordance with JIS K7136:2000. The smaller the haze, the more transparent the polyester film. The results are shown in Table 1.

[0157] [Measurement of tensile strength and tensile elongation] Test pieces measuring 200 mm in the machine direction (MD) and 15 mm in the transverse direction (TD) were cut out from each of the polyester films of Examples 1 and 2 and Comparative Examples 1 and 2. The tensile strength and tensile elongation in the machine direction were measured for each test piece using a tensile tester (Tensilon RTC-125A, manufactured by Orientec Co., Ltd.) at a temperature of 23°C and a relative humidity of 50% RH. The test was performed at a pulling speed of 300 mm / min. Further, test pieces measuring 15 mm in the longitudinal direction and 200 mm in the transverse direction were cut out, and the tensile strength and tensile elongation in the transverse direction of each test piece were measured in the same manner as above. The results are shown in Table 1.

[0158] [Measurement of carbon dioxide and water molecule content] Four test pieces measuring 10 mm long x 3 mm wide were cut out from each of the polyester films of Examples 1 and 2 and Comparative Examples 1 and 2. The total mass of the four test pieces was approximately 35 mg. Thermal desorption spectrometry-mass spectrometry (TDS-MS) was performed under the following conditions to measure the content of carbon dioxide molecules and water molecules in the polyester film. The results are shown in Table 1. (Measurement conditions) ·Device name: Denshi Kagaku EMD-WA1000S / W type Four specimens were heated on the SiC stage. Ionization method: Electron Ionization (EI) Measurement mode: SCAN mode Measurement mass range (m / z): 1 to 200 ·Heating conditions: 50℃~100℃ Heating rate: 10℃ / min Holding temperature and holding time: 100°C for 30 minutes

[0159] [Refractive index measurement] The refractive index at a reference wavelength of 589 nm was measured for each of the polyester films of Example 2 and Comparative Example 2 in accordance with JIS K 7142:2014 (Method A) under the following measurement conditions. The results are shown in Table 1. (Measurement conditions) ·Equipment: Multi-wavelength Abbe refractometer (product name: DR-M2, manufactured by Atago Co., Ltd.) ·Light source wavelength: 589nm Intermediate solution: 1-bromonaphthalene Measurement room temperature: 25±1℃

[0160] [Transmittance measurement] The transmittance at wavelengths of 200 to 800 nm was measured under the following measurement conditions for each of the polyester films of Example 2 and Comparative Example 2. The results are shown in FIG. (Measurement conditions) Equipment: UV-visible spectrophotometer (product name: UV-2700, manufactured by Shimadzu Corporation) Measurement mode: Single, transmittance measurement Slit width: 5.0 nm Measurement wavelength range: 200-800nm Scan speed: Fast Sampling pitch: 0.5nm Light source switching: 360nm

[0161] [Table 1]

[0162] As is clear from Table 1 above and FIG. 17 , the polyester film according to the present disclosure, even though it is a film made from a polyester containing ethylene glycol as a diol unit, which is produced from carbon monoxide gas as a raw material, exhibits physical properties comparable to those of films made from conventional polyesters containing ethylene glycol as a diol unit derived from fossil fuels in terms of transparency, mechanical properties, refractive index, and transmittance, and is therefore suitable for optical applications. Furthermore, it was found that films made from polyesters containing ethylene glycol as a diol unit, which is derived from carbon monoxide gas, contained more carbon dioxide molecules and water molecules than films made from polyesters containing ethylene glycol as a diol unit derived from fossil fuels. [Explanation of symbols]

[0163] 10 Polyester film 20A~20G laminate 21 Sealant layer 21A First Sealant Layer 21B Second sealant layer 30 standing pouches 31 Side sheet 32 Bottom sheet 33 Support 34 Printing layer 41 Pillow Bag 42 3-side seal bag 43 4-side seal bag 50 tube containers 51 Head 52 Cylindrical body 53 Shoulder 54 Spout part 55 Adhesive resin layer 56 Bottom seal 60 Liquid paper containers 61 Torso 62 Bottom 63 Upper 63a Inclined plate 64 Folding section 65 Glue margin 66 Paper layer 70 paper cups 71 Flange 72 Torso 72' body blank 72a' both ends 73 Bottom 73' bottom blank 73a' bend 75 Body sticker

Claims

1. A polyester film comprising a polyester consisting of a diol unit and a dicarboxylic acid unit, The diol unit comprises ethylene glycol derived from at least one gas selected from the group consisting of carbon monoxide and carbon dioxide.

2. The carbon dioxide molecule content is 1.1 x 10 １８ pieces / g or more 3.0×10 １８ The polyester film according to claim 1 , wherein the number of particles per gram is not more than 1 / g.

3. The water molecule content is 8.6 x 10 １９ pieces / g or more 2.5×10 ２０ The polyester film according to claim 1 or 2, wherein the number of particles per gram is not more than 1 / g.

4. 3. The polyester film according to claim 1, wherein the dicarboxylic acid unit comprises at least one selected from the group consisting of terephthalic acid derived from a fossil fuel, terephthalic acid derived from biomass, and terephthalic acid derived from carbon dioxide gas.

5. An optical film comprising the polyester film according to claim 1 or 2.

6. A laminate comprising the polyester film according to claim 1 or 2.

Images