Polyvinyl alcohol resin film, method for distinguishing polyvinyl alcohol resin film, and method for manufacturing polyvinyl alcohol resin film

Abstract

To provide a method for easily and reliably identifying the manufacturer of a PVA film. [Solution] Carbon 14 ( 14 C) abundance ratio 14 A method for distinguishing polyvinyl alcohol resin films by measuring C / C to distinguish between polyvinyl alcohol resin films containing polyvinyl alcohol resin (Ab) whose carbon is derived entirely or partially from biologically derived ethylene (Bb) and polyvinyl alcohol resin films containing only polyvinyl alcohol resin (Ap) whose carbon is derived solely from fossil fuel-derived ethylene (Bp).

Description

[Technical Field]

[0001] The present invention relates to a polyvinyl alcohol resin film containing a polyvinyl alcohol resin, a method for identifying a polyvinyl alcohol resin film, and a method for producing a polyvinyl alcohol resin film. [Background technology]

[0002] Films containing polyvinyl alcohol resin (hereinafter referred to as PVA) have unique properties such as water solubility and optical properties, and are used in a variety of applications that take advantage of these properties, including water-soluble films for pharmaceutical packaging and seed tape, and optical films used as raw materials for polarizing films for LCD displays.

[0003] PVA is known for its biodegradability, which is rare among synthetic resins, and its environmental impact. However, most of the raw materials used to manufacture PVA are derived from compounds derived from fossil fuels such as petroleum, coal, and natural gas. Fossil fuels contain carbon that has been trapped underground for many years. Therefore, decomposing PVA with microorganisms or incinerating it like conventional synthetic resins and releasing carbon dioxide into the atmosphere would release carbon trapped deep underground into the atmosphere as carbon dioxide, potentially contributing to global warming.

[0004] On the other hand, if materials obtained from living organisms (plants and animals) that grow on nutrients that absorb carbon dioxide circulating in the global environment and convert it into organic matter are used as raw materials for synthetic resins, even if they are biodegraded or incinerated to generate carbon dioxide, the total amount of carbon that makes up that carbon dioxide will not change, because the carbon dioxide present in the global environment is circulating.

[0005] Plants, in particular, have attracted attention as carbon sources because they absorb carbon dioxide circulating in the global environment, assimilate it, and fix it as an organic matter through photosynthesis using carbon dioxide and water as raw materials. For example, alcohol components, particularly ethyl alcohol, can be distilled and separated from the fermented sugar or cellulose products extracted from plant materials such as sugarcane and corn, followed by dehydration to obtain the alkene ethylene. This biologically derived ethylene (hereinafter sometimes referred to as bioethylene) can be used as a raw material to synthesize vinyl ester monomers (hereinafter sometimes referred to as biovinyl ester monomers). The resulting polyvinyl esters can then be polymerized and saponified to produce PVA (hereinafter sometimes referred to as bioPVA). Even if this bioPVA is biodegraded or incinerated to generate carbon dioxide, it will not increase the carbon dioxide present in the global environment and will not contribute to global warming.

[0006] The carbon that makes up carbon dioxide circulating in the Earth's environment is the radioactive isotope carbon-14 (hereinafter referred to as 14 C), stable carbon-12 (hereinafter referred to as 12 C), and metastable carbon-13 (hereinafter, 13 C), the mass ratio of which is 12 C is 98.892 mass%, 13 1.108% by mass of C, and 14 C is 1.2 × 10 -12 Mass%~1.2×10 -10 It is known to be a trace amount by mass. 12 C and 13 The ratio of C is stable. 14 C is the neutrons contained in secondary cosmic rays generated by primary cosmic rays in the upper atmosphere that react with nitrogen atoms ( 14 N), so although it fluctuates slightly depending on the strength of sunspot activity, it is constantly being supplied, but at the same time, it decreases with a half-life of 5730 years.

[0007] The carbon that makes up the bodies of living organisms that grow by constantly absorbing carbon dioxide circulating in the Earth's environment is continually renewed during their lives, so they continue to inherit the mass ratio of the three carbon isotopes that make up the carbon dioxide circulating in the Earth's environment.When an organism dies, the mass ratio of the three carbon isotopes within the organism is fixed at the ratio at the time of death. 14 The half-life of C is 5730 years, and it is thought that it was formed in fossil fuels long after the extinction of ancient organisms. 14 The mass ratio of C in carbon dioxide circulating in the Earth's environment is isolated from that of modern carbon dioxide circulating in the Earth's environment. 14 This is a very small value compared to the mass ratio of C.

[0008] Therefore, the carbon that makes up ordinary PVA made from fossil fuels 14 The abundance ratio of C in the carbon that makes up bio-PVA is also 14 The carbon content of bio-PVA is significantly lower than that of fossil fuel-derived PVA, which is essentially 0%. 14 It is possible to distinguish them by measuring the abundance ratio of C.

[0009] Meanwhile, applications of polyvinyl alcohol resin films (hereinafter sometimes referred to as PVA films) containing polyvinyl alcohol resin include raw film used in the production of optical films such as polarizing films, which are components of LCDs in liquid crystal televisions, and pharmaceutical packaging films used to individually package single-dose doses of medicine, and demand for these films has been expanding in recent years. PVA films used for these applications are required to be of extremely high quality, with extremely few defects and almost no unevenness in thickness, etc. Summary of the Invention [Problem to be solved by the invention]

[0010] As described above, PVA film is used for a variety of purposes, including raw material film for optical film manufacturing and pharmaceutical packaging film. However, in the marketplace, problems due to the quality of the PVA film can occur in end products, such as LCD televisions and pharmaceutical packaging, which contain optical films using PVA film. In such cases, it is necessary to determine whether the PVA film causing the problem was manufactured in-house or by another company. However, with conventional techniques, it has been extremely difficult to identify the manufacturer of the PVA film by analyzing the PVA film used in the problematic end product. Therefore, a method for easily and reliably identifying the manufacturer of the PVA film used in problematic end products on the market has been sought.

[0011] Therefore, a first object of the present invention is to provide a PVA film using PVA that does not increase or only increases the amount of carbon dioxide present in the global environment even when biodegraded or incinerated to generate carbon dioxide, and a second object of the present invention is to provide a method for easily and reliably identifying the manufacturer of a PVA film. [Means for solving the problem]

[0012] The National Institute of Standards (NIST) ASTM D6866 is a standard for determining the biogenic carbon content of solid, liquid, and gas samples using radiocarbon dating. The currently valid version of the standard is ASTM D6866-20, which came into effect in February 2020. This method makes it possible to distinguish between films containing bio-based PVA and films containing only fossil-derived PVA.

[0013] That is, the present invention provides: [1] A polyvinyl alcohol resin film containing a polyvinyl alcohol resin (A), wherein the polyvinyl alcohol resin (A) contains 14 carbon atoms ( 14 C) abundance ratio 14 C / C is 1.0×10 -14 A polyvinyl alcohol resin film; [2] Carbon-13( 13 C) carbon stable isotope ratio δ 13 The polyvinyl alcohol resin film according to [1] above, wherein C is -20‰ or more; [3] Carbon-13( 13 C) carbon stable isotope ratio δ 13 The polyvinyl alcohol resin film according to [1] above, wherein C is less than -20‰; [4] The polyvinyl alcohol resin film according to any one of [1] to [3] above, wherein all or part of the polyvinyl alcohol resin (A) is a polyvinyl alcohol resin (Ab) in which all or part of the carbon is derived from biologically-derived ethylene (Bb); [5] The polyvinyl alcohol resin film according to any one of [1] to [4] above, wherein the polyvinyl alcohol resin (A) contains ethylene units, and the content of the ethylene units relative to the total monomer units of the polyvinyl alcohol resin (A) is 1 mol% or more and less than 15 mol%; [6] The polyvinyl alcohol resin film according to any one of [1] to [5], wherein the polyvinyl alcohol resin (A) has a degree of saponification of 80 mol% or more; [7] The polyvinyl alcohol resin film according to any one of [1] to [6], wherein the degree of polymerization of the polyvinyl alcohol resin (A) is 200 or more and less than 8,000; [8] The polyvinyl alcohol resin film according to any one of [1] to [7], wherein the content of 1,2-glycol bonds in the polyvinyl alcohol resin (A) is 0.2 mol% or more and less than 2.0 mol%; [9] The polyvinyl alcohol resin film according to any one of [1] to [8], wherein the polyvinyl alcohol resin (A) has alkoxyl groups at polymer terminals, and the content of the alkoxyl groups relative to the total monomer units of the polyvinyl alcohol resin (A) is 0.0005 mol % or more and less than 1 mol %;

[10] An optical film using the polyvinyl alcohol resin film according to any one of [1] to [9] above;

[11] A water-soluble film using the polyvinyl alcohol resin film according to any one of [1] to [9] above;

[12] A package in which a detergent, pesticide, or disinfectant is packaged with the water-soluble film according to

[11] above;

[13] Carbon 14 ( 14 C) abundance ratio 14 A method for distinguishing polyvinyl alcohol resin films, which distinguishes between polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biologically-derived ethylene (Bb) and polyvinyl alcohol resin films containing only polyvinyl alcohol resins (Ap) whose carbon is derived solely from fossil fuel-derived ethylene (Bp) by measuring C / C;

[14] Carbon 14 in total carbon ( 14 C) abundance ratio 14 a method for distinguishing a polyvinyl alcohol resin film, which distinguishes between a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb) and a polyvinyl alcohol resin film different from the polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb) by measuring C / C;

[15] For polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb), carbon 13 ( 13 C) carbon stable isotope ratio δ 13the method for determining whether the biologically-derived ethylene (Bb) is ethylene (Bb) derived from a C3 plant or ethylene (Bb) derived from a C4 plant, by measuring C;

[16] Carbon-13 ( 13 C) carbon stable isotope ratio δ 13 When the carbon stable isotope ratio δ is -20‰ or more, the biologically derived ethylene (Bb) is determined to be ethylene (Bb) derived from a C4 plant, and 13 the method for determining a polyvinyl alcohol resin film according to

[15] , wherein the biologically-derived ethylene (Bb) is determined to be ethylene (Bb) derived from a C3 plant when C is less than -20‰;

[17] Carbon-13 ( 13 C) carbon stable isotope ratio δ 13 A method for distinguishing polyvinyl alcohol resin films, which distinguishes between polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is wholly or partly derived from biological ethylene (Bb) and polyvinyl alcohol resin films containing only polyvinyl alcohol resins (Ap) whose carbon is derived only from fossil fuel-derived ethylene (Bp) by measuring C;

[18] Carbon-13 ( 13 C) carbon stable isotope ratio δ 13 a method for distinguishing a polyvinyl alcohol resin film, which distinguishes between a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb) and a polyvinyl alcohol resin film different from the polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb) by measuring C;

[19] A method for producing a polyvinyl alcohol resin film, comprising synthesizing a vinyl ester monomer by reacting biologically-derived ethylene (Bb) with a compound having a carboxy group, or synthesizing a vinyl ester monomer by reacting ethylene (Bb) with a compound having a carboxy group, polymerizing the obtained vinyl ester monomer to obtain a polyvinyl ester, saponifying the obtained polyvinyl ester to obtain a polyvinyl alcohol resin (Ab), and producing a polyvinyl alcohol resin film using the obtained polyvinyl alcohol resin (Ab); Regarding. [Effects of the Invention]

[0014] According to the present invention, first, a PVA film using PVA that does not increase or only increases the amount of carbon dioxide present in the global environment even when biodegraded or incinerated to generate carbon dioxide is provided, and second, a method for easily and reliably identifying the manufacturer of a PVA film is provided. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be specifically described below.

[0016] < 14 C abundance ratio> The PVA film of the present invention contains PVA (A) which is a saponified product of polyvinyl ester, and the PVA (A) contains 100% of the total carbon atoms constituting the PVA (A). 14 C abundance ratio 14 C / C (hereinafter, 14 C / C) is 1.0 × 10 -14 That's all. Total carbon is the sum of all carbon isotopes, 14 C / C is the ratio of total carbon 14 C ratio. 14 C / C is 1.0×10 -14If it is less than this, it will be close to the lower limit of measurement in the measurement method according to ASTM D6866, making it difficult to measure with high accuracy, and it will be difficult to determine whether the PVA (A) contained in the PVA film is bio-PVA. 14 A small C / C indicates that the proportion of biologically derived raw materials used in the production of PVA(A) is low, resulting in an insufficient effect in reducing the increase in carbon dioxide in the global environment. 14 C / C is 2.0 x 10 -14 It is preferable that it is 5.0×10 or more. -14 More preferably, it is 1.0×10 -13 More preferably, the above is true. 14 There is no particular upper limit on the C / C ratio, but since biologically derived raw materials are generally more expensive than fossil fuel-derived raw materials, 14 C / C is 1.0 x 10 -11 It is preferable that it is less than 7.0 × 10 -12 It is more preferable that it is less than 5.0 × 10 -12 It is more preferable that:

[0017] In the present invention, 14 There is no particular limitation on the method for measuring C / C. For example, a sample (e.g., vinyl acetate) may be converted into carbon dioxide or graphite as necessary, and then subjected to accelerator mass spectrometry (AMS) to measure the C / C ratio against a standard substance (e.g., oxalic acid from the US NIST). 14 The C content can be determined by comparative measurement. 14 C / C is the 14 It can be calculated by dividing the amount of C by the total amount of carbon in the sample.

[0018] <Carbon stable isotope ratio δ 13 C> In the present invention 13 C stable carbon isotope ratio δ 13 C (hereinafter, δ 13 C) are the three isotopes (abundance ratios) of carbon atoms that exist in nature. 12 C: 13 C: 14C = 98.9:1.11:1.2×10 -12 units; %), among 12 the ratio of 13 C to C, the carbon stable isotope ratio is represented by the deviation from the reference material and refers to the value (δ value) defined by the following formula.

[0019] δ 13 C [‰] = {( 13 C / 12 C) sample / ( 13 C / 12 C) PDB -1.0} × 1,000

[0020] Here, [( 13 C / 12 C) sample represents the stable isotope ratio of the sample to be measured, and [( 13 C / 12 C) PDB represents the stable isotope ratio of the reference material. PDB is an abbreviation for "Pee Dee Belemnite" and means fossils of belemnites composed of calcium carbonate (fossils of belemnites unearthed from the Pee Dee layer in South Carolina as a reference material), 13 C / 12 C ratio is used as a standard. Also, "carbon stable isotope ratio δ 13 C" is measured by accelerator mass spectrometry. Since the reference material is rare, a working standard with a known stable isotope ratio to the reference material can also be used.

[0021] <C3 Plants and C4 Plants> Bioethylene is roughly classified into two major categories depending on the plant used as its raw material. There are those derived from C3 plants such as sweet potatoes, sugar beets, rice, trees, and algae, and those derived from C4 plants such as corn, sugarcane, and cassava. The δ 13 C of both is quite different. In the case of PVA made from bioethylene derived from C3 plants, δ 13 C is less than -20‰, and in the case of PVA made from bioethylene derived from C4 plants, δ 13Therefore, PVA made from bioethylene derived from C3 plants and PVA made from bioethylene derived from C4 plants are different from the above. 14 After measuring C / C to rule out the possibility that the PVA was derived from fossil fuels, δ 13 This can be determined by measuring C.

[0022] Plants are classified into three types based on the type of initial carbon dioxide fixation product in their photosynthetic carbon dioxide fixation pathway: C3 plants, C4 plants, and succulent photosynthetic plants (CAM / Crassulacean Acid Metabolism). Among crops, corn and millet are C4 plants, while major crops such as rice and wheat are C3 plants, and cacti (Cactaceae), safflower (Crassulaceae), and spurge (Euphorbiaceae) are CAM plants.

[0023] More than 90% of plants on Earth belong to the C3 class, including agriculturally useful plants such as rice, barley, tobacco, wheat, potatoes, and palm trees. The enzyme involved in carbon dioxide fixation in the photosynthetic pathway of C3 plants is ribulose-1,5-bisphosphate carboxylase, which has a low affinity for carbon dioxide and a high affinity for oxygen, resulting in low efficiency of the carbon dioxide fixation reaction and, therefore, the photosynthetic reaction.

[0024] The PVA film of the present invention has a carbon-13( 13 C) carbon stable isotope ratio δ 13 It is preferable that C is less than -20‰. 13 C is more preferably -50‰ or more, even more preferably -45‰ or more, and particularly preferably -40‰ or more. 13 C is more preferably −22‰ or less, further preferably −25‰ or less, and particularly preferably −26‰ or less. 13The fact that C is in the above range indicates that the PVA (A) contained in the PVA film is made from bioethylene derived from a C3 plant, which is preferable from the viewpoints of raw material cost, supply availability, etc. Furthermore, preferred C3 plants are rice, wheat, potato, and palm oil.

[0025] C4 plants are plants that perform C4 photosynthesis, a form of photosynthesis that utilizes the C4 pathway for carbon dioxide concentration in addition to the Carbene-Benson cycle, a common carbon dioxide reduction pathway. The enzyme responsible for carbon dioxide fixation in the photosynthetic pathway of C4 plants is phosphoenolpyruvate carboxylase. This enzyme is not inhibited by oxygen, has a high carbon dioxide fixation capacity, and is characterized by the presence of well-developed chloroplasts in bundle sheath cells. Representative C4 plants include corn, sugarcane, cassava, sorghum, miscanthus, guinea grass, rhodes grass, caramel millet, foxtail millet, barnyard millet, finger millet, and broom tree, also known as broom grass, broom tree, or kochia greens. Because C4 plants use extra energy to fix carbon dioxide, they can fix carbon dioxide more efficiently than non-C4 plants. Furthermore, while non-C4 plants have difficulty collecting carbon dioxide at high temperatures, C4 plants do not experience this problem. Moreover, photosynthesis is possible even with little water, which is a physiological adaptation that allows plants to cope with harsh climates such as high temperatures, dryness, low carbon dioxide levels, and nitrogen-poor soils.

[0026] In the PVA film of the present invention, carbon-13( 13 C) carbon stable isotope ratio δ 13 It is preferable that C is -20‰ or more. 13 C is more preferably -18‰ or more, even more preferably -15‰ or more, and particularly preferably -13‰ or more. 13 C is more preferably -1‰ or less, further preferably -4‰ or less, and particularly preferably -7‰ or less. 13The fact that C is in the above range indicates that PVA (A) contained in the PVA film is made from bioethylene derived from C4 plants. Here, bioethylene derived from C4 plants tends to be more difficult to obtain than bioethylene derived from C3 plants. Therefore, the stable carbon isotope ratio δ 13 When C is within the above range, the manufacturer of the PVA film can be more easily and reliably identified. In addition, corn, sugarcane, and cassava are preferred as C4 plants in terms of production volume and cost.

[0027] In addition to C3 and C4 plants, CAM plants have a photosynthetic system adapted to dry environments, and this photosynthetic system is considered to be an evolved form of C3 photosynthesis. 13 C is generally in the range of about -35‰ to about -10‰, and these CAM plants can be used as biomass raw materials in combination as needed within a range that does not impair the effects of the present invention.

[0028] In addition, the PVA film of the present invention 14 C / C, δ if necessary 13 As long as C is within the above range, different 14 C / C or δ 13 A mixture of PVA containing C may be used as a raw material.

[0029] For example, using raw materials derived from C3 plants, 13 Not only did we obtain PVA films that exhibited different δ 13 Mix PVA of C and adjust to the specified δ 13 C, i.e., δ that cannot be achieved by C3 plants alone. 13 Including C, more specific δ 13 By setting the δ 13 When a C raw material is used, the statistical analysis value obtained by analyzing its stable carbon isotope ratio is unique, making it possible to distinguish it from other raw materials. Therefore, the δ 13C also has a unique analytical value, making it easy to identify and track.

[0030] <Polyvinyl alcohol resin> In the PVA film of the present invention, all or part of the PVA (A) is preferably a polyvinyl alcohol resin (Ab) in which all or part of the carbon constituting the PVA (A) is derived from biological ethylene (Bb). That is, in the PVA film of the present invention, the PVA (A) may be PVA (Ab) alone or a mixture of PVA (Ab) and PVA (Ap) obtained only from raw materials derived from fossil fuels.

[0031] There is no particular limitation on the method for obtaining PVA(Ab). For example, (1) A method in which only polyvinyl ester (Db1) obtained by polymerizing only biovinyl ester monomer (Cb1) is saponified to obtain PVA (Ab1), (2) A method of obtaining PVA (Ab2) by saponifying polyvinyl ester (Db2) obtained by polymerizing biovinyl ester monomer (Cb2) made from a mixture of bioethylene (Bb) and fossil fuel-derived ethylene (Bp), (3) a method for obtaining PVA (Ab3) by saponifying polyvinyl ester (Db3) obtained by copolymerizing the biovinyl ester monomer (Cb1) with a vinyl ester monomer (Cp) obtained from fossil fuel-derived ethylene (Bp); (4) A method in which a mixture of the polyvinyl ester (Db1) and a polyvinyl ester (Dp) obtained by polymerizing only a vinyl ester monomer (Cp) derived from a fossil fuel is mixed and saponified to obtain a PVA (Ab4); (5) A method that combines the above methods (2) to (4), Examples include:

[0032] Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate, and among these, vinyl acetate is preferred.

[0033] There are no particular limitations on the method for producing a vinyl ester monomer. For example, it can be obtained by reacting ethylene with a compound having a carboxy group represented by R-COOH. Vinyl acetate can be synthesized as follows. Usually, vinyl acetate can be obtained by reacting ethylene, acetic acid, and oxygen in the gas phase in the presence of a catalyst. At this time, a predetermined amount of 14 A predetermined amount of ethylene or carboxyl group-containing compound containing C 14 By using acetic acid containing C, a specified amount 14 Vinyl acetate containing C is obtained. 14 An example of ethylene containing C is bioethylene.

[0034] In the production of vinyl ester monomers, it is preferable to use raw materials other than ethylene, such as carboxylic acids, that are derived from living organisms. However, since the carboxylic acid group is removed from the polymer backbone of the polyvinyl ester during saponification and is usually recovered and reused, even if fossil fuel-derived materials are used, they do not increase the amount of carbon dioxide present in the global environment and do not contribute to global warming.

[0035] The polyvinyl ester is preferably one obtained using one or more vinyl ester monomers, more preferably one obtained using only one vinyl ester monomer, or may be a copolymer of one or more vinyl ester monomers with other monomers copolymerizable therewith.

[0036] The other monomer copolymerizable with the vinyl ester monomer is preferably ethylene. That is, the PVA contained in the PVA film of the present invention preferably contains ethylene units. The content of ethylene units is preferably 1 mol% or more, more preferably 1.5 mol% or more, based on the number of moles of all structural units constituting the vinyl ester polymer. The content of ethylene units is preferably less than 15 mol% or more, more preferably less than 10 mol%, based on the number of moles of all structural units constituting the vinyl ester polymer. When the PVA film of the present invention is used as a raw film for producing an optical film, the water resistance and other properties of the PVA film can be improved without significantly impairing the optical properties of the PVA film. The reason for this is not entirely clear, but it is presumed that the introduction of ethylene units into the polymer backbone weakens hydrophilicity, while the volume occupied by the ethylene units in the crystal is not significantly different from that of vinyl alcohol units, thereby preventing significant disruption of the PVA crystal structure.

[0037] Examples of other monomers copolymerizable with vinyl ester monomers include, in addition to ethylene, olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or a salt thereof; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or a salt thereof; methyl methacrylate, ethyl methacrylate, methacrylic acid, and the like. Methacrylic acid esters such as n-propyl acrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its salts, and N-methylolacrylamide or its derivatives. acrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or a salt thereof, N-methylolmethacrylamide or a derivative thereof; N-vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, and n-butyl vinyl ether; Examples include vinyl ethers such as i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid or a salt, ester, or acid anhydride thereof; itaconic acid or a salt, ester, or acid anhydride thereof; vinylsilyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.The vinyl ester polymer may have structural units derived from one or more of these other monomers.

[0038] The proportion of structural units derived from other monomers in the polyvinyl ester is preferably 15 mol % or less, and more preferably 5 mol % or less, based on the number of moles of all structural units constituting the polyvinyl ester, from the viewpoints of the strength of the resulting PVA film and the optical performance when the PVA film is used as a raw film for producing an optical film.

[0039] The other monomer copolymerizable with the vinyl ester monomer may be a monomer derived from a fossil fuel or a monomer derived from a plant.

[0040] In the PVA film of the present invention, the degree of polymerization of the PVA (A) is preferably 200 or more. The degree of polymerization of the PVA (A) is preferably less than 8,000. From the viewpoint of the strength of the PVA film, the degree of polymerization of the PVA (A) is more preferably 300 or more, and even more preferably 500 or more. On the other hand, from the viewpoint of the productivity of the PVA (A) or the PVA film, the degree of polymerization of the PVA (A) is more preferably less than 5,000, and even more preferably less than 3,000. Here, the degree of polymerization of the PVA (A) means the average degree of polymerization Po measured in accordance with the description of JIS K6726-1994, and is calculated by the following formula from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30°C after resaponifying and purifying the PVA.

[0041] Po = ([η]×10 4 / 8.29) (1 / 0.62)

[0042] In the PVA film of the present invention, the saponification degree of the PVA (A) is preferably 80 mol% or more. If the saponification degree is less than 80 mol%, the water solubility of the PVA film is likely to be impaired when used as a pharmaceutical packaging film, and the optical properties of the PVA film are likely to be impaired when used as a raw film for producing an optical film. The saponification degree is more preferably 84 mol% or more, and even more preferably 88 mol% or more. On the other hand, the saponification degree is preferably less than 100 mol%, more preferably less than 99.999 mol%, and even more preferably less than 99.995 mol%. Here, the saponification degree of the PVA refers to the ratio (mol%) of the number of moles of vinyl alcohol units to the total number of moles of structural units (typically vinyl ester monomer units) that can be converted to vinyl alcohol units by saponification contained in the PVA and vinyl alcohol units. The saponification degree of the PVA can be measured according to the description of JIS K6726-1994.

[0043] In the PVA film of the present invention, the 1,2-glycol bond content of the PVA (A) is preferably 0.2 mol% or more. The 1,2-glycol bond content of the PVA (A) is preferably less than 2.0 mol%. When the 1,2-glycol bond content is less than 2.0 mol%, good optical properties and mechanical strength can be easily obtained when the PVA film is used as a raw film for producing an optical film. On the other hand, when the 1,2-glycol bond content is 0.2 mol% or more, the productivity in producing the PVA (A) can be improved and the production cost can be reduced. The 1,2-glycol bond content of the PVA (A) is more preferably 0.4 mol% or more, and even more preferably 0.6 mol% or more. The 1,2-glycol bond content of the PVA (A) is more preferably less than 1.9 mol%, and even more preferably less than 1.8 mol%.

[0044] In the PVA film of the present invention, it is preferable that the PVA (A) has an alkoxyl group at the polymer terminal, and the content of the alkoxyl group relative to all monomer units (hereinafter sometimes referred to as the content of terminal alkoxyl groups) is 0.0005 mol% or more. The content of terminal alkoxyl groups is preferably less than 1 mol%. The method for introducing alkoxyl groups into the polymer terminal is not particularly limited, but examples thereof include a method of polymerizing a vinyl ester using a polymerization initiator having an alkoxyl group.

[0045] When the PVA film of the present invention is used as a raw film for producing an optical film, for example, when a polarizing film is produced using the PVA film as a raw film, PVA (A) may dissolve into a treatment solution during the production process. As a result, the concentration of PVA (A) in the treatment solution increases. As a result, PVA (A) fine particles precipitate in the treatment solution due to the progression of boric acid crosslinking and adhere to the PVA film. This can cause problems, such as foreign matter originating from the PVA fine particles remaining on the surface of the resulting polarizing film, resulting in defects. In the PVA film of the present invention, this problem can be prevented by having the PVA (A) have an alkoxyl group at the polymer terminal and by ensuring that the content of this group relative to the total monomer units is 0.0005 mol% or more but less than 1 mol%. If the content of terminal alkoxyl groups is less than 0.0005 mol%, the foreign matter defects on the surface of the polarizing film originating from the PVA (A) fine particles may not be sufficiently reduced. Furthermore, if the content of terminal alkoxyl groups exceeds 1 mol%, when the PVA film of the present invention is used as a raw film for producing an optical film, the resulting polarizing film may have insufficient polarization performance. The content of terminal alkoxyl groups relative to all monomer units is more preferably 0.001 mol% or more, and even more preferably 0.005 mol% or more, and more preferably less than 0.1 mol%, and even more preferably less than 0.05 mol%.

[0046] The PVA film of the present invention may use one type of PVA as PVA (A), or may use a blend of two or more types of PVAs that differ from each other in degree of polymerization, degree of saponification, degree of modification, etc. When using a blend of two or more types of PVAs, PVA (A) may be blended with a PVA derived from biomass other than PVA (A), such as bioethylene, or PVA (A) may be blended with a PVA derived from petroleum or fossil fuels, or both may be combined.

[0047] In the present invention, the content of PVA (A) in the PVA film is not particularly limited, but is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more. Furthermore, the content may be 100% by mass, but considering both the availability of biomass and the performance as a polarizing film, it is preferably 99% by mass or less, 95% by mass or less, or even 90% by mass or less.

[0048] <Plasticizer> The PVA film of the present invention, without a plasticizer, is more rigid than other plastic films, which can lead to problems with mechanical properties such as impact strength and processability during secondary processing. To prevent these problems, it is preferable to incorporate a plasticizer into the PVA film of the present invention. Preferred plasticizers include polyhydric alcohols, such as ethylene glycol, glycerin, diglycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and sorbitol. These plasticizers may be used alone or in combination. Among these plasticizers, ethylene glycol or glycerin are preferred, with glycerin being more preferred, from the viewpoint of preventing bleed-out onto the film surface. It is also preferable to use plasticizers produced from biologically derived raw materials.

[0049] The content of the plasticizer in the PVA film of the present invention is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of PVA contained in the PVA film. The content of the plasticizer is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. If the content of the plasticizer is less than 1 part by mass, the effect of improving the mechanical properties of the PVA film, such as impact strength, may be insufficient. On the other hand, if the content of the plasticizer exceeds 70 parts by mass, the PVA film may become too flexible, resulting in poor handling or bleeding out onto the film surface.

[0050] <Starch / Water-soluble polymer> The PVA film of the present invention may contain a water-soluble polymer other than starch and / or PVA (A). The inclusion of such a water-soluble polymer can impart mechanical strength to the PVA film, maintain moisture resistance during handling of the PVA film, or adjust the rate of softening due to water absorption during dissolution of the PVA film.

[0051] Examples of starches include natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, and sago starch; and processed starches that have been subjected to etherification, esterification, oxidation, or the like, with processed starches being particularly preferred.

[0052] The content of starch in the PVA film is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of PVA (A). If the amount of starch is more than 15 parts by mass, the processability during production of the PVA film may be impaired.

[0053] Examples of water-soluble polymers other than PVA(A) include dextrin, gelatin, glue, casein, shellac, gum arabic, polyacrylic acid amide, sodium polyacrylate, polyvinyl methyl ether, copolymer of methyl vinyl ether and maleic anhydride, copolymer of vinyl acetate and itaconic acid, polyvinylpyrrolidone, cellulose, acetyl cellulose, acetyl butyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and sodium alginate.

[0054] The content of the water-soluble polymer other than PVA (A) in the PVA film is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of PVA (A). If the content of the water-soluble polymer other than PVA (A) exceeds 15 parts by mass, the physical properties of the PVA film may be impaired.

[0055] <Surfactant> In the production of a PVA film, it is preferable to add a surfactant to the PVA film from the viewpoints of improving the handling property and the releasability of the PVA film from the film-forming device during production. Examples of the type of surfactant include anionic surfactants and nonionic surfactants.

[0056] Examples of anionic surfactants include carboxylic acid surfactants such as potassium laurate; sulfate ester surfactants such as octyl sulfate; and sulfonic acid surfactants such as dodecylbenzenesulfonate.

[0057] Examples of nonionic surfactants include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkyl phenyl ether types such as polyoxyethylene octylphenyl ether; alkyl ester types such as polyoxyethylene laurate; alkyl amine types such as polyoxyethylene lauryl amino ether; alkyl amide types such as polyoxyethylene lauric acid amide; polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether; alkanolamide types such as lauric acid diethanolamide and oleic acid diethanolamide; and allyl phenyl ether types such as polyoxyalkylene allyl phenyl ether. The surfactant may be used alone or in combination of two or more.

[0058] <Other ingredients> The PVA film of the present invention may contain, in addition to plasticizers, starch, water-soluble polymers other than PVA (A), and surfactants, components such as water, antioxidants, UV absorbers, lubricants, crosslinking agents, colorants, fillers, preservatives, antifungal agents, and other polymer compounds, to the extent that the effects of the present invention are not impaired. The proportion of the total mass of PVA, plasticizers, starch, water-soluble polymers other than PVA (A), and surfactants to the total mass of the PVA film of the present invention is preferably within the range of 60 to 100% by mass, more preferably within the range of 80 to 100% by mass, and even more preferably within the range of 90 to 100% by mass.

[0059] <Shape> Although there is no particular limitation on the thickness of the PVA film of the present invention, if the thickness is too thick, the secondary processability tends to deteriorate. Therefore, the thickness of the PVA film is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less, and even more preferably 50 μm or less. Also, if the thickness is too thin, there is a possibility that problems may occur in the mechanical strength of the PVA film. Therefore, the thickness of the PVA film is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and particularly preferably 20 μm or more. The thickness of the PVA film can be determined as the average value by measuring the thickness at any 10 locations (for example, any 10 locations on a straight line drawn in the length direction of the PVA film).

[0060] <Use> The PVA film of the present invention is used as a raw film for optical film production or a water-soluble film. Examples of the optical film include a polarizing film, a viewing angle improvement film, a retardation film, a brightness improvement film, etc., and a polarizing film is preferred. Also, examples of the water-soluble film include a film for drug packaging, a base film for hydraulic transfer, a base film for embroidery, a release film for artificial marble molding, a film for seed packaging, a film for a dirt storage bag, etc., and a film for drug packaging is preferred. Examples of the type of drug include, for example, detergents, agricultural chemicals, or bactericides. The form of the drug may be any of powdery,块状, gel状, and liquid状. By using the PVA film of the present invention as a film for drug packaging to package a drug, a package can be obtained. By using this package, a certain amount of drug can be used simply and safely when washing clothes with a detergent in a general household or when spraying agricultural chemicals on a paddy field in agricultural work.

[0061] <Method for producing PVA film> In the present invention, the PVA film can be produced by any method using a film-forming solution prepared by adding a solvent, additives, etc. to PVA (A) to homogenize it. The methods include casting, wet film-forming (discharging into a poor solvent), dry-wet film-forming, gel film-forming (a method in which the film-forming solution is cooled to gel, and then the solvent is extracted and removed to obtain a PVA film), or a combination of these methods. Also, melt extrusion film-forming and inflation film-forming methods, in which the film-forming solution is obtained using an extruder or the like and then extruded through a T-die or the like, can be used to produce a film. Among these, casting and melt extrusion film-forming methods are preferred because they can produce homogeneous films with good productivity. Below, the casting and melt extrusion film-forming methods for PVA films are described.

[0062] When a PVA film is produced by the casting method or the melt extrusion method, the film-forming solution is cast in the form of a film onto a support such as a metal roll or a metal belt, and is heated to remove the solvent, thereby solidifying the film. The solidified film is peeled off from the support, dried with a drying roll or a drying oven, if necessary, further heat-treated if necessary, and wound up to obtain a long roll of PVA film.

[0063] The volatile content concentration of the film-forming solution (the concentration of volatile components such as solvents removed by volatilization or evaporation during film formation) is preferably 50% by mass or more, more preferably 55% by mass or more. The volatile content concentration of the film-forming solution is preferably 90% by mass or less, more preferably 80% by mass or less. If the volatile content concentration is less than 50% by mass, the viscosity of the film-forming solution increases, which may make film formation difficult. On the other hand, if the volatile content concentration exceeds 90% by mass, the viscosity decreases, which may impair the thickness uniformity of the resulting film.

[0064] Here, the "volatile content of the film-forming solution" in this specification refers to the volatile content calculated by the following formula.

[0065] Volatile content of film-forming solution (mass%) = {(Wa-Wb) / Wa} x 100 (Wa represents the mass (g) of the membrane-forming solution, and Wb represents the mass (g) of the membrane-forming solution Wa (g) after drying it in an electric dryer at 105°C for 16 hours.)

[0066] There are no particular limitations on the method for preparing the film-forming solution. Examples include a method in which PVA and additives such as a plasticizer and a surfactant are dissolved in a dissolution tank or the like, or a method in which water-containing PVA is melt-kneaded together with a plasticizer, a surfactant, etc. using a single-screw extruder or a twin-screw extruder.

[0067] When a PVA film is produced by a casting method or a melt extrusion method, the film-forming solution is cast in the form of a film onto a support such as a metal roll or a metal belt from a film-forming extrusion device, and is heated to remove the solvent, thereby solidifying the film.

[0068] The surface temperature of the support onto which the film-forming solution is flowing is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. The surface temperature of the support onto which the film-forming solution is flowing is preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 95°C or lower. If the surface temperature is lower than 50°C, the time required for drying tends to be longer, and productivity tends to decrease. If the surface temperature exceeds 110°C, abnormalities on the film surface such as foaming tend to occur more easily, and the film tends to become too hard.

[0069] The drying speed may be adjusted by simultaneously heating the PVA film on the support and uniformly blowing hot air at a speed of 1 to 10 m / sec onto the entire area of ​​the non-contact side of the PVA film. From the viewpoints of drying efficiency and uniformity of drying, the temperature of the hot air blown onto the non-contact side is preferably 50°C or higher, more preferably 70°C or higher. From the viewpoints of drying efficiency and uniformity of drying, the temperature of the hot air blown onto the non-contact side is preferably 150°C or lower, more preferably 120°C or lower.

[0070] The PVA film peeled from the support is dried on the support, preferably to a volatile content of 5 to 50% by mass, and then peeled off, and further dried as necessary. The drying method is not particularly limited, and examples include contacting the film with a drying oven or drying rolls. When drying is performed with multiple drying rolls, it is preferable to alternately contact one side of the film with the drying rolls to achieve uniformity on both sides. The number of drying rolls is preferably three or more, more preferably four or more, and even more preferably five or more. The number of drying rolls is preferably 30 or less. The upper limit of the temperature of the drying oven and drying rolls is preferably 110°C or less, more preferably 100°C or less, more preferably 90°C or less, and even more preferably 85°C or less. If the temperature of the drying oven and drying rolls is too high, the film may become too hard. On the other hand, the lower limit of the temperature of the drying oven and drying rolls is preferably 40°C or more, more preferably 45°C or more, and even more preferably 50°C or more. If the temperature of the drying oven or drying roll is too low, productivity may decrease.

[0071] The dried PVA film can be further heat-treated as needed. By performing heat treatment, the physical properties of the PVA film, such as strength, water solubility, and birefringence, can be adjusted. The lower limit of the heat treatment temperature is preferably 60°C or higher. The upper limit of the heat treatment temperature is preferably 135°C or lower, more preferably 130°C or lower. If the heat treatment temperature is too high, the film may become too hard.

[0072] The PVA film produced in this manner is further subjected to humidity conditioning treatment, cutting of both ends (edges) of the film, etc., if necessary, and then wound into a roll on a cylindrical core, packaged in moisture-proof packaging, and completed as a finished product.

[0073] The volatile content of the PVA film finally obtained by the above-described series of treatments is not necessarily limited. The volatile content of the PVA film is preferably 1% by mass or more, more preferably 2% by mass or more. The volatile content of the PVA film is preferably 5% by mass or less, more preferably 4% by mass or less.

[0074] <Discrimination method> The PVA film obtained by the above method contains 14 carbon atoms ( 14 C) abundance ratio 14 By measuring the C / C ratio, it is possible to distinguish between PVA films containing PVA (Ab) whose carbon is derived entirely or partially from biologically derived ethylene (Bb) and PVA films containing only PVA (Ap) whose carbon is derived solely from fossil fuel-derived ethylene (Bp).

[0075] In the present invention, PVA (Ap) derived solely from fossil fuel-derived ethylene (Bp) means that it does not contain PVA (Ab) whose carbon is entirely or partially derived from biologically derived ethylene (Bb), and does not exclude PVA (Ap) containing monomer units other than fossil fuel-derived ethylene (Bp). Furthermore, in the present invention, PVA film containing only PVA (Ap) means that it does not contain PVA (Ab) derived from biologically derived ethylene (Bb), and does not exclude PVA films containing components other than PVA (Ap).

[0076] In addition, carbon 14 ( 14 C) abundance ratio 14By measuring the C / C ratio, it is possible to distinguish between a PVA film containing PVA (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb) and another PVA film containing PVA (Ab) whose carbon is derived entirely or partially from biological ethylene (Bb). For example, even if a PVA film contains PVA (Ab) derived from the same plant-derived ethylene (Bb) as a part of the PVA film, if the ratio of PVA (Ab) derived from biological ethylene (Bb) and PVA (Ap) obtained only from fossil fuel-derived raw materials differs, the presence ratio 14 For example, for the PVA film we manufacture, the carbon 14 ( 14 C) abundance ratio 14 By manufacturing PVA film so that the C / C ratio is constant, it is possible to distinguish whether the film is made by one company or another. Even within the same company, carbon-14( 14 C) abundance ratio 14 By manufacturing the compound with different C / C ratios, carbon-14( 14 C) abundance ratio 14 By measuring C / C, it is also possible to identify the manufacturing site, manufacturing date, and manufacturing lot of the PVA film.

[0077] To perform the discrimination of PVA film, the total carbon 14 C abundance ratio 14 C / C is 1.0×10 -14 It is preferable to produce a PVA film so that the viscosity is 5.0 × 10 or more. -14 It is more preferable to manufacture the product so that the concentration is 2.0 × 10 or more. -14 Furthermore, since raw materials derived from living organisms are generally more expensive than raw materials derived from fossil fuels, it is more preferable to manufacture the PVA film so that the total carbon content is equal to or greater than 100%. 14 C abundance ratio 14 C / C is 1.0×10 -11 It is preferable to produce a PVA film with a viscosity of 5.0 × 10 -12It is more preferable to manufacture it so that the concentration is less than 0.1 × 10 -14 It is more preferable to manufacture it as follows.

[0078] Furthermore, carbon 14 ( 14 C) abundance ratio 14 By measuring C / C, the PVA film that was determined to contain PVA (Ab) derived from biological ethylene (Bb) was analyzed using carbon 13 ( 13 C) carbon stable isotope ratio δ 13 By measuring the carbon-13 ( 13 C) carbon stable isotope ratio δ 13 When the carbon stable isotope ratio δ is -20‰ or more, the biologically derived ethylene (Bb) is determined to be ethylene (Bb) derived from a C4 plant, and 13 If the carbon is less than -20‰, the ethylene (Bb) derived from living organisms is identified as ethylene (Bb) derived from C3 plants. 14 C) abundance ratio 14 C / C and carbon-13( 13 C) carbon stable isotope ratio δ 13 By measuring C, PVA films can be identified with higher accuracy.

[0079] Above, carbon 14 ( 14 C) abundance ratio 14 After measuring C / C, the films that were determined to be PVA films containing PVA (Ab) derived from biological ethylene (Bb) were analyzed using carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C was measured, but carbon 14 ( 14 C) abundance ratio 14 No C / C measurement was performed, and carbon-13( 13 C) carbon stable isotope ratio δ 13By measuring C, it is possible to distinguish between a PVA film containing PVA (Ab) whose carbon is derived entirely or partially from biologically derived ethylene (Bb) and other PVA films different from the PVA film. For example, it is possible to distinguish between a PVA film containing PVA (Ab) derived from biologically derived ethylene (Bb) and a PVA film containing only PVA (Ap) obtained only from fossil fuel-derived raw materials. However, the stable carbon isotope ratio δ of PVA (Ap) obtained only from fossil fuel-derived raw materials 13 Since C is generally less than -20‰, it can be difficult to distinguish between PVA films containing PVA (Ab) made from ethylene (Bb) derived from C3 plants and PVA films containing only PVA (Ap) obtained solely from fossil fuel-derived raw materials.

[0080] Furthermore, it is possible to distinguish between a PVA film containing PVA (Ab) derived from biologically-derived ethylene (Bb) and a PVA film containing PVA (Ab) derived from a different biologically-derived ethylene (Bb) from the PVA film.

[0081] As mentioned above, if the blend ratio of bio-PVA and fossil fuel-derived PVA is changed for each PVA film production line, it will be possible to identify which production line's PVA film was used to make the polarizing film by analyzing the polarizers in LCD products available on the consumer market.

[0082] <Application> The PVA film of the present invention can be suitably used for optical applications such as a raw material for polarizing films as described above, and can also be suitably used for water-soluble films such as pharmaceutical packaging and seed tape. [Example]

[0083] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples in any way.

[0084] [Purification of PVA film] The PVA film roll obtained in the following Examples or Comparative Examples was unwound, and approximately 5 g of film was collected and cut into small pieces. The cut PVA film was then extracted with chloroform using a Soxhlet extractor. In this way, components other than PVA in the PVA film were sufficiently removed, purifying the PVA film and obtaining the PVA in the PVA film.

[0085] [Carbon 14 ( 14 C) abundance ratio 14 C / C measurement] The PVA obtained in the above [Purification of PVA film] was converted to CO2 using the pretreatment method (ASTM D6866 / Method B) specified by the American Society of Testing and Materials, and then converted to C (graphite) by complete reduction treatment using an iron catalyst. Next, the carbon isotope ratios ( 14 C / 12 C ratio, 13 C / 12 C ratio) and from the measurement results 12 C concentration, 13 C concentration and 14 The C concentration was calculated. 14 C concentration is the total carbon concentration ( 12 C concentration, 13 C concentration and 14 C) (total concentration) of PVA in the PVA film. 14 The C / C was calculated. Here, the standard substance used was graphite synthesized from the oxalic acid standard substance (HOxII) provided by the National Institute of Standards and Technology of the United States. 14 The measurement limit of C / C is 1.0 × 10 -14 is less than.

[0086] [Carbon stable isotope ratio δ of PVA in PVA film 13 Measurement of C] The PVA obtained in the above [Purification of PVA film] was converted to CO2 using the pretreatment method (ASTM D6866 / Method B) specified by the American Society of Testing and Materials, and then converted to C (graphite) by complete reduction treatment using an iron catalyst. Next, the carbon isotope ratios ( 13 C / 12 The stable carbon isotope ratio δ was calculated using the following formula: 13 C was calculated. Here, PDB ("Pee Dee Belemnite") was used as the standard substance.

[0087] δ 13 C[‰]={( 13 C / 12 C) sample / ( 13 C / 12 C) PDB -1.0}×1,000

[0088] In the above formula, [( 13 C / 12 C) sample ] is the carbon isotope ratio ( 13 C / 12 C ratio), [( 13 C / 12 C) PDB ] is the carbon isotope ratio of the standard PDB ( 13 C / 12 C ratio).

[0089] [Measurement of ethylene unit content, alkoxyl group content, 1,2-glycol bond content and degree of saponification of PVA in PVA film] The PVA obtained in the above "Purification of PVA film" was further purified by dissolving it in dimethyl sulfoxide (DMSO-d6) and then adding the solution to acetone to precipitate the PVA. One or two drops of trifluoroacetic acid (TFA) were added to the DMSO-d6 solution of PVA, and the resulting sample was immediately subjected to NMR measurement under the following conditions. The ethylene unit content, alkoxyl group content, 1,2-glycol bond content, and degree of saponification of the PVA in the PVA film were determined from the obtained NMR spectrum.

[0090] (NMR measurement conditions) Equipment used: JEOL Ltd. superconducting nuclear magnetic resonance spectrometer "Lambda500" Solvent: DMSO-d6 (TFA dropwise) Concentration: 5% by mass Temperature: 80℃ Resonance frequency: 1H 500MHz Flip angle: 45° Pulse delay time: 4.0 seconds Accumulation count: 6000 times

[0091] [Measurement of the stretching limit temperature of PVA film] A rectangular test piece measuring 30 mm in the width direction and 60 mm in the machine direction was taken from the width-direction center of the PVA film roll obtained in the following Examples or Comparative Examples. This test piece was set in a tensile tester with a chuck spacing of 15 mm and then stretched in a thermostatic water bath set at a predetermined temperature to measure the stretch ratio at break. This process was repeated three times, and the average stretch ratio at break was calculated. If this average was 6.5 times or greater, the temperature of the thermostatic water bath was decreased by 1°C. If it was less than 6.5 times, the temperature of the thermostatic water bath was increased by 1°C. The limit temperature at which the average stretch ratio at break was 6.5 times or greater (the lowest temperature at which the average was 6.5 times or greater) was calculated.

[0092] [Evaluation of the number of foreign particles in polarizing film] The polarizing film rolls obtained in the following Examples or Comparative Examples were unwound and cut into pieces of 30 cm in the length direction (stretching direction) and 20 cm in the width direction. The surfaces of the cut polarizing films were visually inspected for blue foreign matter, and the number of foreign matter with a maximum diameter of 5 to 500 μm (pieces / 600 cm) was counted. 2 This was repeated three times to determine the average number of foreign particles (number / 600 cm 2 ) was determined. The longest diameter of the foreign matter was measured using a differential interference microscope (magnification: 200x). In the following examples and comparative examples, the polarized film after drying treatment was continuously wound up for 6 hours, so the cut polarized film was a sample taken approximately 6 hours after the start of polarized film production.

[0093] [Measurement of the polarization degree of polarizing film] The polarized film rolls obtained in the following Examples or Comparative Examples were unwound and cut to a size of 30 cm in the length direction (stretching direction) and 20 cm in the width direction. Two square samples measuring 1.5 cm in the length direction (stretching direction) and 1.5 cm in the width direction were taken from the center of the cut polarized film. The light transmittance (Y∥) when the samples were stacked so that their length directions (stretching directions) were parallel, and the light transmittance (Y⊥) when the samples were stacked so that their length directions (stretching directions) were perpendicular were measured using the same method as for measuring transmittance above. The polarization degree (V) (%) was calculated using the following formula:

[0094] Degree of polarization (V) (%) = {(Y∥-Y⊥) / (Y∥+Y⊥)} 1 / 2 × 100

[0095] Example 1 (1) Synthesis of vinyl acetate Silica spherical carrier "HSV-I" (manufactured by Shanghai Haiyuan Chemical Technology Co., Ltd.) (sphere diameter 5 mm, specific surface area 160 m 223 g of a palladium / g (water absorption coefficient 0.75 g / g) carrier (water absorption amount 19.7 g) was impregnated with an aqueous solution containing 1.5 g of a 56 mass% sodium tetrachloropalladate aqueous solution and 1.5 g of a 17 mass% tetrachloroauric acid tetrahydrate aqueous solution, in an amount equivalent to the carrier's water absorption, and then immersed in 40 mL of an aqueous solution containing 2.5 g of sodium metasilicate nonahydrate and allowed to stand for 20 hours. Subsequently, 3.3 mL of a 52 mass% hydrazine hydrate aqueous solution was added, and the carrier was allowed to stand for 4 hours at room temperature. The resulting carrier was then washed with water until chloride ions were completely removed, and dried at 110 °C for 4 hours. The resulting palladium / gold / carrier composition was immersed in 60 mL of a 1.7 mass% acetic acid aqueous solution and allowed to stand for 16 hours. It was then washed with water for 16 hours and dried at 110 °C for 4 hours. The carrier was then impregnated with 2 g of potassium acetate in an aqueous solution equivalent to the carrier's water absorption, and dried at 110 °C for 4 hours to obtain a vinyl acetate synthesis catalyst.

[0096] 3 mL of the resulting catalyst was diluted with 75 mL of glass beads and packed into a SUS316L reaction tube (inner diameter 22 mm, length 480 mm). The reaction was carried out at a reaction temperature of 150°C, a reaction pressure of 0.6 MPaG, and a gas mixture of ethylene / oxygen / water / acetic acid / nitrogen = 47.3 / 6.1 / 5.6 / 26.3 / 14.7 (mol%) at a flow rate of 20 NL / h. The ethylene used here was sugarcane-derived bioethylene (manufactured by Braskem SA). The resulting reaction gas containing vinyl acetate was purified to obtain vinyl acetate.

[0097] (2) Synthesis of PVA Polymerization was carried out at 60°C using the vinyl acetate obtained above as the monomer, 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile) as the polymerization initiator, and methanol as the solvent by a known method. Two moles of 2,4-diphenyl-4-methyl-1-pentene (DPMP), a compound with a conjugated double bond and a molecular weight of 1,000 or less, were then added per mole of the polymerization initiator. The polymerization time was adjusted to the desired degree of polymerization. A 6% by mass solution of sodium hydroxide in methanol was added to the resulting methanol solution with stirring, so that the molar ratio of sodium hydroxide to vinyl acetate units in the polyvinyl acetate was 0.023. The saponification reaction was initiated at 30°C. A gel formed as the saponification reaction progressed. After 50 minutes had elapsed since the start of the saponification reaction, the gel was crushed to obtain methanol-swollen PVA (PVA-1). This PVA-1 was washed with five times its mass of methanol, and then dried with hot air at 55°C for 1 hour and at 100°C for 2 hours.

[0098] (3) Manufacturing of PVA film and PVA film rolls The resulting aqueous solution (PVA concentration: 15% by mass) containing 100 parts by mass of PVA-1, 12 parts by mass of glycerin, and 0.1 parts by mass of lauric acid diethanolamide was prepared as a PVA film dope. This dope was extruded through a slit die onto a 2-m diameter first metal roll (with a surface temperature of 90°C) and dried. The resulting film, with a moisture content of 12% by mass, was peeled off from the metal roll. The film was then dried by contacting the side of the film that had not been in contact with the first metal roll with a 1-m diameter second metal roll (with a surface temperature of 70°C). The film was then dried by contacting the third to sixth metal rolls (surface temperatures of 80 to 120°C, diameter of 1 m) in sequence, with one side of the film alternately contacting the metal rolls, and then wound up to obtain a PVA film roll with a width of 0.6 m, a length of 1000 m, and a thickness of 30 μm (PVA film roll).

[0099] (4) Manufacturing of polarizing film The resulting PVA film roll was unwound and subjected to swelling, dyeing, crosslinking, stretching, washing, and drying in this order to continuously produce polarized film. The swelling treatment involved immersing the PVA film in a swelling bath containing a treatment liquid (pure water) at 30°C and uniaxially stretching the film to 1.72 times its original length. The dyeing treatment involved immersing the PVA film in a swelling bath containing a treatment liquid (aqueous solution of 2.8% by mass of boric acid and 5% by mass of potassium iodide) at 32°C and uniaxially stretching the film to 1.37 times its original length. The crosslinking treatment involved immersing the PVA film in a swelling bath containing a crosslinking treatment liquid (aqueous solution of 2.6% by mass of boric acid) at 32°C and uniaxially stretching the film to 1.12 times its original length. The stretching treatment was carried out by uniaxially stretching the PVA film in the longitudinal direction by 2.31 times in a swelling treatment bath containing a stretching treatment solution (aqueous solution of 2.8% by mass of boric acid and 5% by mass of potassium iodide) at 55°C. The washing treatment was carried out by immersing the PVA film in a washing treatment bath containing a washing treatment solution (aqueous solution of 1.5% by mass of boric acid and 5% by mass of potassium iodide) at 22°C for 12 seconds. The drying treatment was carried out by drying the PVA film at 60°C for 1.5 minutes. The PVA film was not stretched during the washing and drying treatments. The PVA film roll obtained in this way was unwound to continuously produce polarized films.

[0100] (5) Manufacture of polarized film rolls Two square samples measuring 1.5 cm in the length direction (stretching direction) and 1.5 cm in the width direction were taken from the center of the width direction of the obtained polarized film. Each was measured using a Hitachi V-7100 spectrophotometer (with integrating sphere) in accordance with JIS Z8722 (Method for measuring object color) using luminosity correction in the visible light region with a C light source and a 2-degree field of view. For one polarized film sample, the light transmittance was measured when the sample was tilted 45 degrees and -45 degrees relative to the stretching axis direction, and the average value (Y1) of these transmittances was calculated.

[0101] For the other polarizing film sample, the light transmittance was measured in the same manner as above when tilted at 45 degrees and when tilted at -45 degrees, and the average value (Y2) was calculated. The average of Y1 and Y2 calculated above was used as the transmittance (Y) (%) of the polarizing film.

[0102] The concentrations of iodine and potassium iodide in the swelling treatment tank were adjusted so that the transmittance was 43.5%, and the polarized film after drying was then continuously wound up for 6 hours to obtain a roll of polarized film (polarized film roll).

[0103] The PVA film roll and polarizing film roll thus obtained were measured and evaluated by the methods described above. The measurement and evaluation results are shown in Table 2. The raw materials and polymerization conditions for the PVA are shown in Table 1.

[0104] <Example 2> PVA (PVA-2) was obtained in the same manner as in Example 1, except that the polymerization initiator used in "(2) Synthesis of PVA" above was changed to azobisisobutyronitrile. Then, a PVA film roll and a polarized film roll were produced in the same manner as in Example 1, except that PVA-2 was used, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for PVA are shown in Table 1.

[0105] Example 3 PVA (PVA-3) was obtained in the same manner as in Example 1, except that the PVA polymerization temperature in "(2) Synthesis of PVA" above was changed to 90°C. Then, a PVA film roll and a polarized film roll were produced in the same manner as in Example 1, except that PVA-3 was used, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for PVA are shown in Table 1.

[0106] <Comparative Example 1> PVA (PVA-4) was obtained in the same manner as in Example 1, except that the ethylene used in the above "(1) Synthesis of vinyl acetate" was replaced with petroleum-derived ethylene (manufactured by Air Liquide Kogyo Gas Co., Ltd.). Then, a PVA film roll and a polarized film roll were produced in the same manner as in Example 1, except that PVA-4 was used, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for PVA are shown in Table 1.

[0107] Example 4 The PVA used in the above "(3) Production of PVA film and PVA film roll" A PVA film roll and a polarized film roll were produced, and measurements and evaluations were carried out in the same manner as in Example 1, except that the PVA used was a 1:1 mixture of PVA-4 obtained in Comparative Example 1 and PVA-1 obtained in Example 1. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for the PVA are also shown in Table 1.

[0108] <Example 5> PVA (PVA-5) was obtained in the same manner as in Example 1, except that 5.7 parts by mass of sugarcane-derived bioethylene (manufactured by Braskem SA) was added per 100 parts by mass of vinyl acetate as the monomer used in "(2) Synthesis of PVA" above, and the polymerization reaction was carried out while maintaining the pressure inside the reaction vessel at 0.03 MPaG. Then, PVA film rolls and polarized film rolls were produced in the same manner as in Example 1, except that PVA-5 was used, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for PVA are shown in Table 1.

[0109] Example 6 Rice, a C3 plant, was treated with alkali, saccharification, and ethanol to obtain rice-derived ethanol. This ethanol was then dehydrated at 190°C using mordenite as a catalyst to produce rice-derived bioethylene.

[0110] PVA (PVA-6) was obtained in the same manner as in Example 1, except that the ethylene used in the above "(1) Synthesis of vinyl acetate" was replaced with this rice-derived bioethylene. A PVA film roll and a polarized film roll were produced in the same manner as in Example 1, except that PVA-6 was used, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. The raw materials and polymerization conditions for PVA are shown in Table 1.

[0111] [Table 1]

[0112] [Table 2]

Claims

1. Polyvinyl alcohol is obtained by removing components other than polyvinyl alcohol from a polyvinyl alcohol resin film, The carbon 14 ( １４ C) abundance ratio １４ A method for distinguishing polyvinyl alcohol resin films, comprising measuring C / C, and if 14 C / C is 1.0×10 −14 or more, distinguishing the film as a polyvinyl alcohol resin film containing polyvinyl alcohol resin (Ab) derived entirely or partly from biologically derived ethylene (Bb), and if 14 C / C is less than 1.0×10 −14 , distinguishing the film as a polyvinyl alcohol resin film containing only polyvinyl alcohol resin (Ap) derived exclusively from fossil fuel-derived ethylene (Bp).

2. Polyvinyl alcohol is obtained by removing components other than polyvinyl alcohol from a polyvinyl alcohol resin film, The carbon 14 ( １４ C) abundance ratio １４ A method for distinguishing polyvinyl alcohol resin films, which distinguishes between polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biologically-derived ethylene (Bb) and polyvinyl alcohol resin films that are different from the polyvinyl alcohol resin films and contain polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biologically-derived ethylene (Bb) by measuring C / C.

3. For a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) in which all or part of the carbon is derived from biological ethylene (Bb), carbon 13 ( １３ C) carbon stable isotope ratio δ １３ 3. The method for determining a polyvinyl alcohol resin film according to claim 1 or 2, wherein the method determines whether the biologically-derived ethylene (Bb) is ethylene (Bb) derived from a C3 plant or ethylene (Bb) derived from a C4 plant by measuring C.

4. Carbon 13 ( １３ C) carbon stable isotope ratio δ １３ When the carbon stable isotope ratio δ is −20‰ or more, the biologically derived ethylene (Bb) is determined to be ethylene (Bb) derived from a C4 plant, and １３ The method for determining a polyvinyl alcohol resin film according to claim 3, wherein the biologically derived ethylene (Bb) is determined to be ethylene (Bb) derived from a C3 plant when C is less than -20‰.

5. Polyvinyl alcohol is obtained by removing components other than polyvinyl alcohol from a polyvinyl alcohol resin film, The carbon 13 ( １３ C) carbon stable isotope ratio δ １３ A method for distinguishing polyvinyl alcohol resin films, which distinguishes between polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from ethylene (Bb) derived from C4 plants and polyvinyl alcohol resin films containing only polyvinyl alcohol resins (Ap) whose carbon is derived solely from ethylene (Bp) derived from fossil fuels, by measuring C.

6. Polyvinyl alcohol is obtained by removing components other than polyvinyl alcohol from a polyvinyl alcohol resin film, The carbon 13 ( １３ C) carbon stable isotope ratio δ １３ A method for distinguishing polyvinyl alcohol resin films, which distinguishes between polyvinyl alcohol resin films containing polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biologically-derived ethylene (Bb) and polyvinyl alcohol resin films which are different from the polyvinyl alcohol resin films and contain polyvinyl alcohol resins (Ab) whose carbon is derived entirely or partially from biologically-derived ethylene (Bb) by measuring C.

7. A vinyl ester monomer is synthesized by reacting ethylene (Bb), the carbon of which is wholly or partly derived from a living organism, with a compound having a carboxy group, or by reacting ethylene with １４ a compound having a carboxy group containing C to synthesize a vinyl ester monomer; The resulting vinyl ester monomer is polymerized to obtain a polyvinyl ester; The obtained polyvinyl ester is saponified to obtain a polyvinyl alcohol resin (Ab), The obtained polyvinyl alcohol resin (Ab) is used to produce a polyvinyl alcohol resin film, 7. The method for identifying a polyvinyl alcohol resin film according to claim 1, wherein the abundance ratio of carbon-14 ( 14 C) to total carbon in the produced polyvinyl alcohol resin film, 14 C / C, or the carbon stable isotope ratio δ 13 C of carbon-13 ( 13 C) in total carbon in the produced polyvinyl alcohol resin film is measured.

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