Polyvinyl alcohol resin film, method for discriminating polyvinyl alcohol resin film, and method for producing polyvinyl alcohol resin film

Abstract

A polyvinyl alcohol resin film, a method for discriminating a polyvinyl alcohol resin film, and a method for producing a polyvinyl alcohol resin film. Provided are: a PVA film which does not increase the amount of carbon dioxide present in the global environment even when carbon dioxide is generated by a biodegradation treatment or an incineration treatment; and a method for easily and reliably discriminating a manufacturer of the PVA film. The polyvinyl alcohol resin film contains a polyvinyl alcohol resin (A), and the abundance ratio 14C / C of C14 in the total carbon constituting the polyvinyl alcohol resin (A) is 1.0 * 10-14 or more. A method for discriminating a polyvinyl alcohol resin film, which discriminates a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) in which all or part of carbon is derived from ethylene (Bb) derived from a organism, and a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ap) only derived from ethylene (Bp) derived from a fossil fuel, by measuring the abundance ratio 14C / C of C14 in the total carbon, and a method for discriminating a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) containing only a polyvinyl alcohol resin (Ap) only derived from ethylene (Bp) derived from a fossil fuel.

Description

[0001] This application is a divisional application of an application with an application date of October 14, 2021, application number 202180007345.8, and invention name “Polyvinyl alcohol resin film, method for identifying polyvinyl alcohol resin film, and method for manufacturing polyvinyl alcohol resin film”. Technical Field

[0002] The present invention relates to a polyvinyl alcohol resin film containing a polyvinyl alcohol resin, a method for distinguishing the polyvinyl alcohol resin film, and a method for producing the polyvinyl alcohol resin film. Background Art

[0003] Films containing polyvinyl alcohol resin (hereinafter sometimes referred to as PVA) are used in various applications such as water-soluble films such as drug packaging, seed tapes, and optical films used as raw materials for polarizing films of liquid crystal displays due to their unique properties such as water solubility and optical properties.

[0004] PVA has a rare biodegradability as a synthetic resin, and is also known as a synthetic resin with little environmental load. However, most of the raw materials used to make PVA are manufactured using compounds derived from fossil fuels such as petroleum, coal, and natural gas as starting materials. Fossil fuels contain carbon that has been fixed underground for a long time. Therefore, the carbon dioxide released into the atmosphere by decomposing PVA using microorganisms or burning it like a common synthetic resin is carbon that is fixed deep underground rather than in the atmosphere, and will be released into the atmosphere in the form of carbon dioxide, which may become a factor in global warming.

[0005] On the other hand, if materials obtained from organisms (plants, animals) that grow by absorbing carbon dioxide circulating in the earth's environment and converting it into a nutrient source for organic matter are used as raw materials for synthetic resins, even if carbon dioxide is produced by biodegradation or incineration, the total amount of carbon that constitutes the carbon dioxide will not change due to the carbon dioxide cycle that exists in the earth's environment.

[0006] In particular, plants have attracted much attention as carbon sources because they absorb carbon dioxide circulating in the earth's environment, use carbon dioxide and water as raw materials for photosynthesis reaction, and assimilate and immobilize organisms in the form of organisms. For example, the fermentation of sugar extracted from plant raw materials such as sugarcane and corn or the distillation separation of alcohol components, especially ethanol, from cellulose fermentation, and ethylene as olefins can be obtained by its dehydration reaction. If the following PVA (hereinafter, sometimes referred to as bio-PVA) is manufactured, even if the bio-PVA is subjected to biodegradation treatment or incineration treatment to produce carbon dioxide, the carbon dioxide present in the earth's environment will not be increased, and it will not become the cause of global warming. The PVA is synthesized from the ethylene (hereinafter, sometimes referred to as bio-ethylene) of the biological source as a raw material vinyl ester monomer (hereinafter, sometimes referred to as bio-vinyl ester monomer), the bio-vinyl ester monomer is polymerized to obtain polyvinyl ester, and the polyvinyl ester is saponified to obtain PVA.

[0007] It is known that the carbon that constitutes the carbon dioxide circulating in the earth's environment is radioactive carbon 14 (hereinafter sometimes referred to as 14 C), stable carbon 12 (hereinafter sometimes referred to as 12 C) and semi-stable carbon 13 (hereinafter sometimes referred to as 13 C) a mixture having a mass ratio of: 12 C is 98.892 mass%, 13 C is 1.108 mass%, and 14 C is 1.2×10 -12 Mass%~1.2×10 -10 Mass % (trace amount). 12 C and 13 The ratio of C is stable. Radioactive 14 C is generated by neutrons contained in secondary cosmic rays generated by primary cosmic rays in the upper atmosphere, which collide with nitrogen atoms in the atmosphere ( 14 N), so it fluctuates slightly depending on the strength of sunspot activity, but it is always supplied continuously. On the other hand, it decreases with a half-life of 5730 years.

[0008] The carbon that makes up an organism that continuously absorbs carbon dioxide circulating in the earth's environment and grows is constantly renewed during its life, so the mass ratio of the three carbon isotopes that make up carbon dioxide circulating in the earth's environment continues. When an organism dies, the mass ratio of the three carbon isotopes inside the organism is fixed at the ratio at the time of death. 14 The half-life of C is 5730 years. Since it is isolated from modern carbon dioxide circulating in the earth's environment, it is not present in fossil fuels that were formed a long time after the death of organisms living in ancient times. 14The mass ratio of C to the carbon dioxide circulating in the earth's environment 14 Compared with the mass ratio of C, it is a very small value.

[0009] Therefore, the carbon content of conventional PVA made from fossil fuels is 14 The presence ratio of C also varies with the carbon content of bio-PVA. 14 Compared with the existence ratio of C, it is a significantly smaller value, substantially 0%. Therefore, if the carbon content is measured, 14 The presence ratio of C can distinguish bio-PVA from PVA derived from fossil fuels.

[0010] By the way, the use of polyvinyl alcohol resin film (hereinafter sometimes referred to as PVA film) containing polyvinyl alcohol resin includes raw film for manufacturing optical films such as polarizing films as components of LCDs such as liquid crystal televisions, and film for packaging medicines for packaging medicines in single doses, and the demand for such films has continued to expand in recent years. For PVA films used in these applications, very high quality is required, such as very few bad pixels and almost no uneven thickness. Summary of the invention

[0011] Problem that the invention aims to solve

[0012] As mentioned above, PVA film is used for various purposes such as blank film for manufacturing optical film, film for pharmaceutical packaging, etc., but in the market, in the final products such as LCD TV and pharmaceutical packaging body containing optical film using PVA film, sometimes problems originating from the quality of PVA film occur. In this case, it is necessary to specify whether the PVA film causing the problem is manufactured by the company itself or by other companies. However, in the known technology in the past, it is very difficult to specify the manufacturer of the PVA film by analyzing the PVA film used for the final product that causes the problem. Therefore, a method for easily and reliably distinguishing the manufacturer of the PVA film used for the final product that causes the problem in the market is needed.

[0013] Therefore, the first object of the present invention is to provide a PVA film using PVA that does not increase the carbon dioxide present in the earth's environment or increases the amount of carbon dioxide even if it is subjected to biodegradation treatment or incineration treatment. In addition, the second object of the present invention is to provide a method for easily and reliably identifying the manufacturer of the PVA film.

[0014] Solutions for solving problems

[0015] Regarding the distinction between organic matter derived from plants and organic matter derived from fossil fuels, ASTM D6866 based on the National Institute of Standards (NIST) of the United States is known. ASTM D6866 is a standard rule of ASTM (American Society for Testing and Materials) for determining the concentration of biogenic carbon in solid, liquid, and gas samples using radiocarbon dating, and the current version of the standard rule is ASTM D6866-20 implemented in February 2020. This method can distinguish between a film containing bio-PVA and a film containing only fossil fuel-derived PVA without containing bio-PVA.

[0016] That is, the present invention relates to the following scheme:

[0017] [1] A polyvinyl alcohol resin film comprising a polyvinyl alcohol resin (A), wherein carbon 14 ( 14 C) existence ratio 14 C / C is 1.0×10 -14 above;

[0018] [2] The polyvinyl alcohol resin film according to [1], wherein carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is above -20‰;

[0019] [3] The polyvinyl alcohol resin film according to [1], wherein carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is lower than -20‰;

[0020] [4] The polyvinyl alcohol resin film according to any one of [1] to [3], 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 ethylene (Bb) of biological origin;

[0021] [5] The polyvinyl alcohol resin film according to any one of [1] to [4], wherein the polyvinyl alcohol resin (A) contains ethylene units, and the content of the ethylene units is 1 mol% or more and less than 15 mol% based on all monomer units of the polyvinyl alcohol resin (A);

[0022] [6] The polyvinyl alcohol resin film according to any one of [1] to [5], wherein the degree of saponification of the polyvinyl alcohol resin (A) is 80 mol% or more;

[0023] [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 8000;

[0024] [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%;

[0025] [9] The polyvinyl alcohol resin film according to any one of [1] to [8], wherein the polyvinyl alcohol resin (A) has an alkoxy group at a polymer terminal, and the content of the alkoxy group is 0.0005 mol% or more and less than 1 mol% based on all monomer units of the polyvinyl alcohol resin (A);

[0026]

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

[0027]

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

[0028]

[12] A package obtained by packaging a detergent, a pesticide, or a fungicide with the water-soluble film described in

[11] above;

[0029]

[13] A method for identifying polyvinyl alcohol resin films by measuring the carbon 14 ( 14 C) existence ratio 14 C / C, thereby distinguishing a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) in which all or part of the carbon is derived from ethylene (Bb) of a bio-source, and a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ap) only containing ethylene (Bp) derived only from a fossil fuel source;

[0030]

[14] A method for identifying polyvinyl alcohol resin films by measuring the carbon 14 ( 14 C) existence ratio 14 C / C, thereby distinguishing a polyvinyl alcohol resin film of a polyvinyl alcohol resin (Ab) containing carbon all or partly derived from ethylene (Bb) of biological origin, and a polyvinyl alcohol resin film other than the polyvinyl alcohol resin film, containing a polyvinyl alcohol resin (Ab) containing carbon all or partly derived from ethylene (Bb) of biological origin;

[0031]

[15] The method for identifying a polyvinyl alcohol resin film according to

[13] or

[14] , wherein for a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) in which all or part of the carbon is derived from ethylene (Bb) of a biological origin, the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C, thereby determining whether the biologically derived ethylene (Bb) is ethylene (Bb) derived from C3 plants or ethylene (Bb) derived from C4 plants;

[0032]

[16] The method for determining a polyvinyl alcohol resin film according to

[15] , wherein the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 When C is -20‰ or above, the ethylene (Bb) of biological origin is judged to be ethylene (Bb) of C4 plant origin. 13 When C is lower than -20‰, the biologically derived ethylene (Bb) is identified as ethylene (Bb) from C3 plants;

[0033]

[17] A method for identifying polyvinyl alcohol resin films by measuring carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C, thereby distinguishing a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ab) whose carbon is all or partly derived from ethylene (Bb) of biological origin, and a polyvinyl alcohol resin film containing a polyvinyl alcohol resin (Ap) only containing ethylene (Bp) derived only from fossil fuel sources;

[0034]

[18] A method for identifying polyvinyl alcohol resin films by measuring carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C, thereby distinguishing a polyvinyl alcohol resin film of a polyvinyl alcohol resin (Ab) containing carbon all or part of which is derived from ethylene (Bb) of biological origin, from another polyvinyl alcohol resin film of a polyvinyl alcohol resin (Ab) containing carbon all or part of which is derived from ethylene (Bb) of biological origin;

[0035]

[19] A method for producing a polyvinyl alcohol resin film, wherein:

[0036] A vinyl ester monomer is synthesized by reacting bio-derived ethylene (Bb) with a compound having a carboxyl group, or a vinyl ester monomer is synthesized by reacting ethylene (Bb) with a compound having a carboxyl group,

[0037] The obtained vinyl ester monomer is polymerized to obtain polyvinyl ester,

[0038] The obtained polyvinyl ester is saponified to obtain a polyvinyl alcohol resin (Ab).

[0039] A polyvinyl alcohol resin film was produced using the obtained polyvinyl alcohol resin (Ab).

[0040] Effects of the Invention

[0041] According to the present invention, first, a PVA film is provided which does not increase the carbon dioxide in the earth's environment or increases the amount of PVA by a small amount even if it is subjected to biodegradation treatment or incineration treatment to generate carbon dioxide. In addition, according to the present invention, second, a method for easily and reliably identifying the manufacturer of the PVA film is provided. DETAILED DESCRIPTION

[0042] Hereinafter, the present invention will be described in detail.

[0043] < 14 The existence ratio of C>

[0044] The PVA film of the present invention comprises PVA (A) which is a saponified product of polyvinyl ester, wherein the total carbon content of the PVA (A) is 14 The existence ratio of C 14 C / C (hereinafter, sometimes referred to as 14 C / C) is 1.0×10 -14 Total carbon refers to the sum of all carbon isotopes. 14 C / C means, 14 The ratio of C to total carbon. 14 C / C is less than 1.0×10 -14 In the case of , it becomes close to the lower limit of the measurement method according to ASTM D6866, making it difficult to measure with good accuracy, and it becomes difficult to determine whether the PVA (A) contained in the PVA film is bio-PVA. 14 A small C / C means that the ratio of the bio-derived raw material used in the production of PVA (A) is small, and the effect of reducing the increase in the amount of carbon dioxide present in the global environment becomes insufficient. 14 C / C is preferably 2.0×10 -14 More preferably 5.0×10 -14 More preferably, 1.0×10 -13 On the other hand, 14 There is no particular upper limit on C / C. Biomass raw materials are generally more expensive than fossil fuel-derived raw materials. 14 C / C is preferably 1.0×10 -11 Below, more preferably 7.0×10 -12 Below, more preferably 5.0×10 -12 the following.

[0045] In the present invention, 14 The method for measuring C / C is not particularly limited. For example, a sample (e.g., vinyl acetate) may be converted into carbon dioxide and graphite as needed, and then the carbon dioxide and graphite may be compared with a standard substance (e.g., U.S. NIST oxalic acid) by accelerator mass spectrometry (AMS). 14 The C content can be compared and determined to obtain 14 C / C. 14 C / C can be measured by 14 The amount of C was calculated by dividing the amount of carbon in the sample.

[0046] <Carbon stable isotope ratio δ 13 C>

[0047] The present invention 13 The carbon stable isotope ratio δ 13 C (hereinafter, sometimes denoted as δ 13 C) refers to the three isotopes of carbon atoms that exist in nature (existence ratio 12 C: 13 C: 14 C=98.9:1.11:1.2×10 -12 Unit: %) 13 C relative to 12 The ratio of C, the carbon stable isotope ratio, is expressed as a deviation from a standard substance and refers to a value (δ value) defined by the following formula.

[0048] δ 13 C[‰]={( 13 C / 12 C) sample / ( 13 C / 12 C) PDB -1.0}×1000

[0049] Here, [( 13 C / 12 C) sample ] refers to the stable isotope ratio of the sample to be measured, [( 13 C / 12 C) PDB ] refers to the stable isotope ratio of a standard substance. PDB is the abbreviation for "Stable Isotope Mass Spectrum (Pee Dee Belemnite)", which refers to the belemnite fossils formed by calcium carbonate (the belemnite fossils unearthed from the Pee Dee Formation in South Carolina are used as standard substances) as 13 C / 12C ratio standard. In addition, the "carbon stable isotope ratio δ 13 C" is determined by accelerator mass spectrometry. It should be noted that, due to the scarcity of standard substances, a universal standard with a known stable isotope ratio relative to the standard substance can also be used.

[0050] <C3 plants and C4 plants>

[0051] Bioethylene is roughly divided into two types according to the plants used as bioethylene raw materials: one comes from C3 plants such as sweet potatoes, beets, rice, trees, and algae, and the other comes from C4 plants such as corn, sugar cane, and cassava. 13 In the case of PVA using bioethylene from C3 plants as raw material, δ 13 C is lower than -20‰, while in the case of PVA using bioethylene from C4 plants as raw material, δ 13 Therefore, for PVA using bioethylene derived from C3 plants as raw materials and PVA using bioethylene derived from C4 plants as raw materials, the above 14 After excluding the possibility of PVA from fossil fuels by C / C, δ 13 C can be judged.

[0052] Plants are divided into three types according to the type of initial carbon dioxide fixation product in their photosynthetic carbon dioxide fixation pathway: C3 plants, C4 plants, and succulent photosynthesis (CAM / Crassulacean Acid Metabolism) plants. Among crops, corn and grains are C4 plants, major crops such as rice and wheat are C3 plants, and Cactaceae, Crassulaceae, Euphorbiaceae, etc. are CAM plants.

[0053] More than 90% of plants on Earth are C3 plants, including agriculturally useful plants such as rice, wheat, tobacco, wheat, potatoes, and palm. The enzyme involved in the fixation of carbon dioxide in the photosynthesis pathway of C3 plants is ribulose-1,5-bisphosphate carboxylase, which has a low affinity for carbon dioxide and a high affinity for oxygen. Therefore, the efficiency of the carbon dioxide fixation reaction and the photosynthesis reaction is low.

[0054] The PVA film of the present invention is preferably based on the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is lower than -20‰. 13 C is more preferably -50‰ or more, further preferably -45‰ or more, and particularly preferably -40‰ or more. 13C is more preferably -22‰ or less, further preferably -25‰ or less, and particularly preferably -26‰ or less. The carbon stable isotope ratio δ 13 C in the above range means that PVA (A) contained in the PVA film uses PVA made of bioethylene derived from C3 plants as a raw material, which is preferred from the perspective of raw material cost, supply, etc. In addition, rice, wheat, potato, and palm oil are preferred as C3 plants.

[0055] C4 plants are plants that perform C4 photosynthesis, which refers to a photosynthesis form that has a C4 pathway for enriching carbon dioxide in addition to the Calvin-Benson cycle, which is a common carbon dioxide reduction cycle, during the photosynthesis process. In the photosynthesis pathway of this C4 plant, the enzyme involved in carbon dioxide fixation is phosphoenolpyruvate carboxylase. This enzyme is not affected by the activity inhibition caused by oxygen, has a high carbon dioxide fixation ability, and is characterized by the presence of developed chloroplasts in the vascular bundle sheath cells. Representative C4 plants include corn, sugarcane, cassava, sorghum, pampas grass, millet, Gai's tiger tail grass, four-brachiate grass, foxtail grass, barnyard grass,  seeds, Kochia scoparia, etc. Kochia scoparia is another name, also known as broom grass, falling broom, peacock pine. The above-mentioned C4 plants use extra energy to fix carbon dioxide, so they can fix carbon dioxide with good efficiency compared to other plants other than C4 plants. In addition, other plants other than C4 plants are difficult to collect carbon dioxide at high temperatures, but C4 plants are not. Moreover, even a small amount of water can fully carry out photosynthesis. It is the physiological adaptation of plants to the harsh climate such as high temperature, dryness, low carbon dioxide, and nitrogen-poor soil.

[0056] In the PVA film of the present invention, the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is preferably -20‰ or more. 13 C is more preferably -18‰ or more, further 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. The carbon stable isotope ratio δ 13 The above range of C means that PVA (A) contained in the PVA film uses PVA made of C4 plant-derived bioethylene as a raw material. Here, since C4 plant-derived bioethylene tends to be more difficult to obtain than C3 plant-derived bioethylene, the carbon stable isotope ratio δ in the PVA film of the present invention is determined by the carbon stable 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, as C4 plants, corn, sugar cane, and cassava are preferred from the perspective of production volume and cost.

[0057] In addition, CAM plants, which are plants other than C3 plants and C4 plants, have a photosynthesis system that is suitable for dry environments and is considered to be an evolutionary form of C3 photosynthesis. 13 C is generally in the range of about -35‰ to about -10‰, and these CAM plants can be used in combination as needed as a biomass raw material within the range that does not hinder the effects of the present invention.

[0058] In addition, the PVA film of the present invention only needs 14 C / C, δ as needed 13 C can be within the above range, and a mixture with different 14 C / C, or δ 13 C of PVA as raw material.

[0059] For example, not only can C3 plant-derived raw materials be used to obtain 13 C PVA film, and can be different δ 13 C PVA is mixed to obtain the specified δ 13 C, including δ that cannot be achieved by C3 plants alone 13 More specific δ including C 13 C, thereby further improving the discrimination accuracy of the obtained PVA film. 13 C raw material, the statistical analysis value obtained by analyzing its carbon stable isotope ratio is a unique value, so it can be distinguished from other raw materials. Therefore, the δ 13 C also has inherent analytical value, which facilitates identification and tracking.

[0060] <Polyvinyl alcohol resin>

[0061] In the PVA film of the present invention, it is preferred that all or part of PVA (A) is a polyvinyl alcohol resin (Ab) in which all or part of the carbon constituting the PVA (A) is derived from ethylene (Bb) of biological origin. That is, in the PVA film of the present invention, 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.

[0062] There is no particular limitation on the method for obtaining PVA (Ab), and for example, the following method can be exemplified:

[0063] Method (1), polymerizing only bio-vinyl ester monomer (Cb1) to obtain polyvinyl ester (Db1), and saponifying only the obtained polyvinyl ester (Db1) to obtain PVA (Ab1);

[0064] Method (2), polymerizing a bio-vinyl ester monomer (Cb2) using a mixture of bio-ethylene (Bb) and fossil fuel-derived ethylene (Bp) as a raw material to obtain polyvinyl ester (Db2), and saponifying the obtained polyvinyl ester (Db2) to obtain PVA (Ab2);

[0065] Method (3), copolymerizing the aforementioned bio-vinyl ester monomer (Cb1) with a vinyl ester monomer (Cp) using ethylene (Bp) derived from fossil fuel as a raw material to obtain polyvinyl ester (Db3), and saponifying the obtained polyvinyl ester (Db3) to obtain PVA (Ab3);

[0066] Method (4), mixing the aforementioned polyvinyl ester (Db1) with a polyvinyl ester (Dp) obtained by polymerizing only a fossil fuel-derived vinyl ester monomer (Cp), and saponifying the mixture to obtain PVA (Ab4);

[0067] Method (5), a method combining the above methods (2) to (4); etc.

[0068] Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate. Among these, vinyl acetate is preferred.

[0069] The method for producing the vinyl ester monomer is not particularly limited, and the vinyl ester monomer can be obtained, for example, by reacting ethylene with a compound having a carboxyl group represented by R-COOH. Vinyl acetate can be synthesized as follows. Generally, vinyl acetate can be obtained by reacting ethylene, acetic acid, and oxygen in a gas phase in the presence of a catalyst. In this case, by using a mixture containing a predetermined amount of 14 C of ethylene, or by using a 14 C of acetic acid as a compound having a carboxyl group, thereby obtaining a product containing a predetermined amount of 14 C of vinyl acetate. As containing a specified amount 14 As ethylene of C, for example, bioethylene can be mentioned.

[0070] It should be noted that in the production of vinyl ester monomers, it is preferred to use raw materials other than ethylene, such as carboxylic acids of biological origin, but the carboxylic acid group is removed from the polymer backbone of the polyvinyl ester during saponification and is usually recovered and reused. Therefore, even if fossil fuel sources are used, the carbon dioxide present in the earth's environment will not increase, and it will not become a cause of global warming.

[0071] The polyvinyl ester is preferably obtained using one or more vinyl ester monomers, and more preferably obtained using only one vinyl ester monomer. In addition, the polyvinyl ester may be a copolymer of one or more vinyl ester monomers and other monomers copolymerizable therewith.

[0072] As other monomers copolymerizable with vinyl ester monomers, ethylene is preferred. That is, the PVA contained in the PVA film of the present invention preferably contains ethylene units. In addition, the content of ethylene units is based on the molar number of all structural units constituting the vinyl ester polymer, preferably 1 mol% or more, more preferably 1.5 mol% or more. In addition, the content of ethylene units is based on the molar number of all structural units constituting the vinyl ester polymer, preferably less than 15 mol%, more preferably less than 10 mol%. The content of ethylene units is within the above range, so that when the PVA film of the present invention is used as a raw film for the manufacture of optical films, water resistance can be improved, etc., without greatly damaging the optical properties of the PVA film. The reason may not be very clear, but it is presumed that this is because ethylene units are introduced into the polymer main chain to weaken hydrophilicity, and there is no significant difference between the volume occupied by ethylene units and the volume occupied by vinyl alcohol units in the crystal, so the structure of PVA is not greatly disturbed.

[0073] Examples of other monomers copolymerizable with the vinyl ester monomer include, in addition to ethylene, olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutylene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its salts, N-hydroxy Acrylamide derivatives such as methacrylamide or its derivatives; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salts, methacrylamidepropyldimethylamine or its salts, N-hydroxymethylmethacrylamide or its derivatives; N-vinylamides such as N-vinylformamide, N-vinylacetamide, and N-vinylpyrrolidone; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-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 its salts, esters, or anhydrides; itaconic acid or its salts, esters, or anhydrides; vinyl silyl compounds such as vinyltrimethoxysilane; isopropenyl acetate, etc. The vinyl ester polymer may have structural units derived from one or more of these other monomers.

[0074] The proportion of structural units derived from other monomers in polyvinyl ester is preferably 15 mol% or less, more preferably 5 mol% or less based on the molar number of all structural units constituting polyvinyl ester, from the viewpoint of the strength of the resulting PVA film, the optical properties when the PVA film is used as a raw film for the manufacture of an optical film, etc.

[0075] Other monomers copolymerizable with the vinyl ester monomer may be monomers derived from fossil fuels or monomers derived from plants.

[0076] In the PVA film of the present invention, the degree of polymerization of PVA(A) is preferably 200 or more. The degree of polymerization of PVA(A) is preferably less than 8000. From the viewpoint of the strength of the PVA film, the degree of polymerization of PVA(A) is more preferably 300 or more, and further preferably 500 or more. On the other hand, from the viewpoint of the productivity of PVA(A) or PVA film, the degree of polymerization of PVA(A) is more preferably less than 5000, and further preferably less than 3000. The degree of polymerization of PVA(A) herein refers to the average degree of polymerization Po measured in accordance with the description of JIS K6726-1994, which is obtained by the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30°C after re-saponification and purification of PVA according to the following formula.

[0077] Po=([η]×10 4 / 8.29) (1 / 0.62)

[0078] In the PVA film of the present invention, the saponification degree of PVA (A) is preferably 80 mol% or more. When the saponification degree is less than 80 mol%, the water solubility is easily impaired when the PVA film is used as a film for drug packaging. In addition, when the PVA film is used as a raw film for optical film manufacturing, the optical properties are easily impaired. The saponification degree is more preferably 84 mol% or more, and 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 more preferably less than 99.995 mol%. The saponification degree of PVA here refers to the ratio (mol%) of the mole number of the vinyl alcohol unit relative to the total mole number of the structural unit (typically a vinyl ester monomer unit) and the vinyl alcohol unit that can be converted into the vinyl alcohol unit by saponification possessed by PVA. The saponification degree of PVA can be measured according to the records of JIS K6726-1994.

[0079] In the PVA film of the present invention, the content of 1,2-glycol bonds in PVA (A) is preferably 0.2 mol% or more. The content of 1,2-glycol bonds in PVA (A) is preferably less than 2.0 mol%. By having a 1,2-glycol bond content of less than 2.0 mol%, it is easy to obtain good optical properties and mechanical strength when using the PVA film as a raw film for optical film manufacturing. On the other hand, by having a 1,2-glycol bond content of more than 0.2 mol%, the productivity when manufacturing PVA (A) can be improved and the manufacturing cost can be reduced. The content of 1,2-glycol bonds in PVA (A) is more preferably 0.4 mol% or more, and further preferably 0.6 mol% or more. The content of 1,2-glycol bonds in PVA (A) is more preferably less than 1.9 mol%, and further preferably less than 1.8 mol%.

[0080] In the PVA film of the present invention, it is preferred that PVA (A) has an alkoxy group at the polymer terminal, and the content of the alkoxy group relative to all monomer units (hereinafter, sometimes referred to as the content of the terminal alkoxy group) is 0.0005 mol% or more. The content of the terminal alkoxy group is preferably less than 1 mol%. There is no particular limitation on the method for introducing the alkoxy group into the polymer terminal, and for example, a method for polymerizing a vinyl ester using a polymerization initiator having an alkoxy group can be cited.

[0081] When the PVA film of the present invention is used as a raw film for manufacturing an optical film, for example, when a polarizing film is manufactured using the PVA film as a raw film, if PVA (A) is dissolved into the treatment solution during the manufacturing process and the concentration of PVA (A) in the treatment solution increases, the fine particles of PVA (A) will be precipitated in the treatment solution and attached to the PVA film due to the progress of boric acid cross-linking, etc., and foreign matter originating from the PVA fine particles will remain on the surface of the obtained polarizing film and become bad points, so problems sometimes arise. In the PVA film of the present invention, the occurrence of such problems can be suppressed by having an alkoxy group at the polymer terminal of PVA (A) and its content relative to all monomer units being 0.0005 mol% or more and less than 1 mol%. When the content of the terminal alkoxy group is less than 0.0005 mol%, it is sometimes impossible to fully reduce the foreign matter bad points on the surface of the polarizing film originating from the fine particles of PVA (A). In addition, when the content of terminal alkoxy exceeds 1 mol%, when the PVA film of the present invention is used as a raw film for optical film production, there is a concern that the polarization performance of the obtained polarizing film becomes insufficient. The content of terminal alkoxy is more preferably 0.001 mol% or more, and more preferably 0.005 mol% or more relative to all monomer units. The content of terminal alkoxy is more preferably less than 0.1 mol%, and more preferably less than 0.05 mol% relative to all monomer units.

[0082] 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 PVA having different polymerization degrees, saponification degrees or modification degrees. When two or more types of PVA are used, PVA (A) may be blended with a PVA derived from biomass such as bioethylene other than PVA (A), or may be blended with a PVA derived from petroleum or fossils, or both may be combined.

[0083] In the present invention, the content of PVA (A) in the PVA film is not particularly limited, preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 85% by mass or more. In addition, the content may be 100% by mass, and if the availability of biomass and the performance as a polarizing film are taken into consideration, it is preferably 99% by mass or less, 95% by mass or less, and further 90% by mass or less.

[0084] <Plasticizer>

[0085] The PVA film of the present invention is rigid compared with other plastic films when it does not contain a plasticizer, and mechanical properties such as impact strength and process passability during secondary processing sometimes become problems. In order to prevent these problems, the PVA film of the present invention preferably contains a plasticizer. As a preferred plasticizer, polyols can be cited, specifically, for example, polyols such as ethylene glycol, glycerol, dipropylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and sorbitol can be cited. These plasticizers can be used alone or in combination of two or more. Among these plasticizers, ethylene glycol or glycerol are preferred, and glycerol is more preferred from the viewpoint of not being easy to seep out to the film surface. In addition, the plasticizer is also preferably made from raw materials of biological origin.

[0086] 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 further preferably 5 parts by mass or more relative to 100 parts by mass of PVA contained in the PVA film. In addition, the content of the plasticizer is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less. If the content of the plasticizer is less than 1 part by mass, the improvement effect of the mechanical properties such as the impact strength of the PVA film is sometimes insufficient. On the other hand, if the content of the plasticizer exceeds 70 parts by mass, the PVA film is sometimes too soft and the operability is reduced, or it oozes out on the film surface.

[0087] <Starch / Water-soluble polymer>

[0088] The PVA film of the present invention may contain water-soluble polymers other than starch and / or PVA (A). By containing such water-soluble polymers, mechanical strength can be imparted to the PVA film, moisture resistance during operation of the PVA film can be maintained, or the speed of softening caused by water absorption during dissolution of the PVA film can be adjusted.

[0089] Examples of starch include natural starches such as corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, and sago starch; and processed starches such as those subjected to etherification, esterification, and oxidation. Processed starches are particularly preferred.

[0090] 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 greater than 15 parts by mass, there is a concern that process performance may deteriorate when manufacturing the PVA film.

[0091] Examples of water-soluble polymers other than PVA (A) include dextrin, gelatin, glue, casein, shellac, gum arabic, polyacrylamide, sodium polyacrylate, polyvinyl methyl ether, a copolymer of methyl vinyl ether and maleic anhydride, a copolymer of vinyl acetate and itaconic acid, polyvinyl pyrrolidone, cellulose, acetyl cellulose, acetobutyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, sodium alginate, and the like.

[0092] The content of water-soluble polymers other than PVA (A) 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 content of water-soluble polymers other than PVA (A) is greater than 15 parts by mass, there is a concern that the physical properties of the PVA film may be impaired.

[0093] <Surfactant>

[0094] In the PVA film film-making process, from the viewpoints of its operability and the stripping property of the homemade film device when improving the manufacture of the PVA film, it is preferred to add a surfactant in the PVA film. As the type of surfactant, anionic surfactants, nonionic surfactants, etc. can be exemplified.

[0095] Examples of the anionic surfactant include carboxylic acid type surfactants such as potassium laurate; sulfate ester type surfactants such as octyl sulfate; and sulfonic acid type surfactants such as dodecylbenzenesulfonate.

[0096] Examples of the nonionic surfactant include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkyl phenyl ether types such as polyoxyethylene octyl phenyl 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; alkanol amide types such as lauric acid diethanolamide and oleic acid diethanolamide; allyl phenyl ether types such as polyoxyalkylene allyl phenyl ether, and the like.

[0097] The surfactant may be used alone or in combination of two or more.

[0098] <Other ingredients>

[0099] The PVA film of the present invention may contain water, antioxidant, ultraviolet absorber, lubricant, cross-linking agent, colorant, filler, preservative, mildewproof agent, other polymer compounds and other components in addition to plasticizer, starch, water-soluble polymer other than PVA (A), surfactant within the range that does not hinder the effect of the present invention. The total value of each mass of water-soluble polymer other than PVA, plasticizer, starch, PVA (A), and surfactant in the total mass of the PVA film of the present invention is preferably within the range of 60 to 100 mass %, more preferably within the range of 80 to 100 mass %, and further preferably within the range of 90 to 100 mass %.

[0100] <Shape>

[0101] The thickness of the PVA film of the present invention is not particularly limited, but if the thickness is too thick, there is a tendency for the secondary processability to deteriorate. Therefore, the thickness of the PVA film is preferably 200 μm or less, more preferably 150 μm or less, further preferably 100 μm or less, and further preferably 50 μm or less. In addition, if the thickness is too thin, there is a concern that the PVA film will have problems in mechanical strength. Therefore, the thickness of the PVA film is preferably 5 μm or more, more preferably 10 μm or more, further preferably 15 μm or more, and particularly preferably 20 μm or more. It should be noted that the thickness of the PVA film can be obtained as follows: the thickness of any 10 places (for example, any 10 places located on a straight line drawn in the length direction of the PVA film) is measured and obtained as their average value.

[0102] <Application>

[0103] The PVA film of the present invention can be used as a raw film or water-soluble film for the manufacture of optical films. As optical films, polarizing films, viewing angle improvement films, phase difference films, brightness improvement films, etc. can be exemplified, preferably polarizing films. In addition, as water-soluble films, films for drug packaging, base films for hydraulic transfer, base films for embroidery, demolding films for artificial marble forming, seed packaging films, films for pollutant storage bags, etc. can be exemplified, preferably films for drug packaging. As the type of drug, for example, detergents, pesticides, or fungicides can be cited. As the form of the drug, it can be powder, block, gel and liquid. By using the PVA film of the present invention as a drug packaging film to package the drug, a package body can be obtained. By using this package body, a prescribed amount of drug can be used simply and safely when using detergent to wash clothes in ordinary households and when spreading pesticides to rice fields during agricultural operations.

[0104] <Method for producing PVA film>

[0105] In the present invention, the method for manufacturing a PVA film is as follows: a method for making a film by using a film-making stock solution obtained by adding a solvent, an additive, etc. to PVA (A) and homogenizing it, and using a cast film method, a wet film method (discharging into a poor solvent), a dry-wet film method, a gel film method (a method of temporarily cooling and gelling the film-making stock solution, extracting and removing the solvent, and obtaining a PVA film) or a combination thereof; using an extruder or the like to obtain the above-mentioned film-making stock solution, and extruding it from a T-die head or the like to make a film by any method such as a melt extrusion film method, an inflation molding method, etc. to make a film. Among these, the cast film method and the melt extrusion film method can obtain a homogeneous film with good productivity, so they are preferred. Below, the cast film method or the melt extrusion film method of the PVA film is described.

[0106] When a PVA film is made by a casting film method or a melt extrusion film method, the film-making stock solution is cast in a film-like state onto a support such as a metal roll or a metal belt, and heated to remove the solvent, thereby solidifying and forming a film. The solidified film is peeled off from the support, dried by a drying roll, a drying furnace, etc. as needed, and further heat-treated and wound up as needed to obtain a long-sized PVA film in a roll.

[0107] The volatile component concentration of the above-mentioned film-forming stock solution (the concentration of volatile components such as solvents removed by volatilization or evaporation during film formation) is preferably 50% by mass or more, and more preferably 55% by mass or more. The volatile component concentration of the film-forming stock solution is preferably 90% by mass or less, and more preferably 80% by mass or less. If the volatile component concentration is less than 50% by mass, the viscosity of the film-forming stock solution becomes high, and film formation may become difficult. On the other hand, if the volatile component concentration exceeds 90% by mass, the viscosity becomes low, and the thickness uniformity of the obtained film is easily impaired.

[0108] Here, the "volatile content of the membrane-forming stock solution" in this specification means the volatile content calculated according to the following formula.

[0109] Volatile content of film-forming stock solution (mass %) = {(Wa-Wb) / Wa}×100

[0110] (Wa represents the mass (g) of the film-forming stock solution, and Wb represents the mass (g) of the film-forming stock solution when Wa (g) is dried in an electric drying machine at 105°C for 16 hours.)

[0111] There is no particular limitation on the method for adjusting the film-forming stock solution. For example, the following methods can be cited: a method of dissolving PVA and additives such as plasticizers and surfactants in a dissolving tank or the like; a method of melt-kneading the water-containing PVA together with plasticizers, surfactants, etc. using a single-screw extruder or a twin-screw extruder; etc.

[0112] When a PVA film is produced by cast film production or melt extrusion film production, the film-forming stock solution is cast in a film form from a film-forming discharge device onto a support such as a metal roll or a metal belt and heated to remove the solvent, thereby solidifying and forming a film.

[0113] The surface temperature of the support for the cast film stock solution is preferably 50°C or higher, more preferably 60°C or higher, and further preferably 65°C or higher. The surface temperature of the support for the cast film stock solution is preferably 110°C or lower, more preferably 100°C or lower, and further preferably 95°C or lower. When the surface temperature is lower than 50°C, the time required for drying becomes longer, and there is a tendency for productivity to decrease. When the surface temperature exceeds 110°C, there is a tendency for film surface abnormalities such as foaming to occur easily, and the film tends to be too hard.

[0114] The drying speed can be adjusted by uniformly blowing hot air at a wind speed of 1 to 10 m / s to the entire area of ​​the non-contact surface side of the PVA film while heating the PVA film on the support. From the aspects of drying efficiency, drying uniformity, etc., the temperature of the hot air blown to the non-contact surface side is preferably 50°C or more, more preferably 70°C or more. From the aspects of drying efficiency, drying uniformity, etc., the temperature of the hot air blown to the non-contact surface side is preferably 150°C or less, more preferably 120°C or less.

[0115] The PVA film peeled off from the support is dried on the support until the volatile content is preferably 5 to 50% by mass, and then peeled off and further dried as needed. There is no particular limitation on the drying method, and a method of contacting with a drying furnace or a drying roller can be cited. When drying with multiple drying rollers, it is preferred to alternately contact one side and the other side of the film with the drying rollers to make both sides uniform. The number of drying rollers is preferably 3 or more, more preferably 4 or more, and further preferably 5 or more. The number of drying rollers is preferably 30 or less. The upper limit of the temperature of the drying furnace and the drying roller is preferably 110°C or less, more preferably 100°C or less, more preferably 90°C or less, and further preferably 85°C or less. If the temperature of the drying furnace and the drying roller is too high, there is a concern that the film becomes too hard. On the other hand, the lower limit of the temperature of the drying furnace and the drying roller is preferably 40°C or more, more preferably 45°C or more, and further preferably 50°C or more. If the temperature of the drying furnace and the drying roller is too low, there is a concern that productivity will decrease.

[0116] The dried PVA film can be further heat-treated as needed. By heat-treating, 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 above 60°C. The upper limit of the heat treatment temperature is preferably below 135°C, and more preferably below 130°C. If the heat treatment temperature is too high, there is a concern that the film may become too hard.

[0117] The PVA film thus produced is further subjected to humidity control treatment as necessary, and the film is wound up in a roll on lined paper or a cylindrical core after both ends (ear parts) of the film are cut and the roll is then moisture-proof packaged as a product.

[0118] The volatile content of the PVA film finally obtained by the above 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.

[0119] <Judgment method>

[0120] The PVA film obtained by the above method can be identified as follows: by measuring the carbon 14 ( 14 C) existence ratio 14 C / C can distinguish between PVA films containing PVA (Ab) in which all or part of the carbon comes from ethylene (Bb) derived from biological sources and PVA films containing only ethylene (Bp) derived from fossil fuel sources (Ap).

[0121] It should be noted that, in the present invention, PVA (Ap) derived only from ethylene (Bp) from fossil fuels refers to PVA (Ab) that does not contain all or part of the carbon derived from ethylene (Bb) from biological sources, and does not exclude the concept of PVA (Ap) containing other monomer units other than ethylene (Bp) from fossil fuels. In addition, in the present invention, a PVA film containing only PVA (Ap) refers to PVA (Ab) that does not contain ethylene (Bb) from biological sources, and does not exclude the concept of PVA films containing components other than PVA (Ap).

[0122] In addition, by determining the carbon 14 in the total carbon ( 14 C) existence ratio 14 C / C can be used to distinguish a PVA film containing PVA (Ab) whose carbon is all or partly derived from ethylene (Bb) of biological origin, from another PVA film containing PVA (Ab) whose carbon is all or partly derived from ethylene (Bb) of biological origin. For example, even if a PVA film partially contains PVA (Ab) whose carbon is all or partly derived from ethylene (Bb) of the same plant origin, if the ratio of PVA (Ab) derived from ethylene (Bb) of biological origin to PVA (Ap) obtained only from raw materials of fossil fuels is different, there is a ratio 14 C / C varies. For example, for PVA film manufactured by our company, the carbon content of the total carbon is 14 ( 14 C) existence ratio 14C / C is constant during manufacturing, so that it is possible to distinguish whether the PVA film is a product of one's own company or another company. In addition, even within the same enterprise, the carbon 14 ( 14 C) existence ratio 14 C / C is manufactured in different ways, so that according to carbon 14 ( 14 C) existence ratio 14 The measurement of C / C can also identify the manufacturing location, manufacturing date, and manufacturing batch of the PVA film.

[0123] In order to perform the discrimination of PVA film, it is preferred to use the total carbon content. 14 The existence ratio of C 14 C / C becomes 1.0×10 -14 The PVA film is produced in the above manner, and more preferably, the film is 5.0×10 -14 The above method is used for manufacturing, and it is more preferable to make 2.0×10 -14 In addition, raw materials from biological sources are generally more expensive than raw materials from fossil fuels. Therefore, in order to perform the discrimination of PVA films, it is preferred to use the total carbon content. 14 The existence ratio of C 14 C / C becomes 1.0×10 -11 The PVA film is manufactured in the following manner, preferably with a thickness of 5.0×10 -12 The following method is used for manufacturing, and it is more preferable to make 0.1×10 -14 The production is carried out in the following manner.

[0124] Further, regarding the determination of carbon 14 ( 14 C) existence ratio 14 C / C, thus determining the PVA film to be PVA (Ab) containing ethylene (Bb) from biological sources, and measuring carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C, it is possible to distinguish whether the biologically derived ethylene (Bb) is derived from C3 plants or C4 plants. More specifically, at the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 When C is -20‰ or above, the ethylene (Bb) of biological origin is judged to be ethylene (Bb) of C4 plant origin. 13 When C is lower than -20‰, the ethylene (Bb) of biological origin is identified as ethylene (Bb) from C3 plants. 14 C) existence ratio 14 C / C, and carbon 13 (13 C) carbon stable isotope ratio δ 13 C, so that the PVA film can be identified with higher accuracy.

[0125] Above, regarding the determination of carbon 14 in total carbon ( 14 C) existence ratio 14 Based on the C / C ratio, the PVA film was identified as PVA (Ab) containing ethylene (Bb) derived from biological sources. Although the carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C, but no carbon 14 ( 14 C) existence ratio 14 C / C determination, carbon 13 ( 13 C) carbon stable isotope ratio δ 13 The determination of C can distinguish a PVA film containing PVA (Ab) whose carbon is all or partly derived from ethylene (Bb) derived from biological sources, and a PVA film different from the PVA film. For example, a PVA film containing PVA (Ab) derived from biological sources ethylene (Bb) and a PVA film containing only PVA (Ap) obtained from raw materials derived from fossil fuels can be distinguished. Among them, the carbon stable isotope ratio δ 13 C usually becomes lower than -20‰, so it is sometimes difficult to distinguish between a PVA film containing PVA (Ab) using ethylene (Bb) derived from C3 plants as a raw material and a PVA film containing only PVA (Ap) obtained from raw materials derived from fossil fuels.

[0126] Furthermore, it is also possible to distinguish a PVA film of PVA (Ab) containing bio-derived ethylene (Bb) and a PVA film of PVA (Ab) containing bio-derived ethylene (Bb) which is different from the PVA film.

[0127] As described above, if the mixing ratio of bio-PVA and fossil fuel-derived PVA used in the production line of each PVA film is changed, the polarizing plates of LCD products available in the consumer market can be analyzed to determine which production line's PVA film is used as raw material for the specific polarizing film used.

[0128] <Application>

[0129] As described above, the PVA film of the present invention can be suitably used for optical applications such as a raw material for polarizing films, and can also be suitably used for water-soluble films such as medicine packaging and seed tapes.

[0130] Example

[0131] Hereinafter, the present invention will be specifically described based on examples and the like, but the present invention is not limited to the following examples at all.

[0132] [Purification of PVA film]

[0133] The PVA film obtained in the following examples or comparative examples was unrolled and about 5 g of the film was collected and cut into small pieces. Then, the cut PVA film was extracted with chloroform in a Soxhlet extractor. In this way, the PVA film was purified by fully removing components other than PVA in the PVA film, thereby obtaining PVA in the PVA film.

[0134] [Carbon 14 ( 14 C) existence ratio 14 Determination of C / C]

[0135] The PVA obtained in the above [Purification of PVA Film] was subjected to CO2 conversion by the pretreatment method (ASTM D6866 / Method B) specified by the American Society of Testing and Materials, and then subjected to C (graphitization) conversion by complete reduction treatment using an iron catalyst. Next, the carbon isotope ratio ( 14 C / 12 C ratio, 13 C / 12 C ratio), and from these measurement results, we can find 12 C concentration, 13 C concentration and 14 C concentration. Then, the obtained 14 C concentration divided by the total carbon concentration ( 12 C concentration, 13 C concentration and 14 C concentration), and thus the PVA in the PVA film was calculated. 14 C / C. Here, graphite synthesized from oxalic acid standard material (HOxII) provided by the U.S. National Institute of Standards and Technology was used as the standard material. 14 The determination limit of C / C is less than 1.0×10 -14 .

[0136] [Carbon stable isotope ratio of PVA in PVA film δ 13 Determination of C]

[0137] The PVA obtained in the above [Purification of PVA Film] was subjected to CO2 conversion according to the pretreatment method (ASTM D6866 / Method B) specified by the American Society of Testing and Materials, and then subjected to C (graphitization) conversion by complete reduction treatment using an iron catalyst. Next, the carbon isotope ratio ( 13 C / 12 C ratio). Then, the carbon stable isotope ratio δ is calculated according to the following formula: 13 C. Here, PDB ("Pee Dee Belemnite") was used as a standard substance.

[0138] δ 13 C[‰]={( 13 C / 12 C) sample / ( 13 C / 12 C) PDB -1.0}×1000

[0139] In the above formula, [( 13 C / 12 C) sample ] represents the carbon isotope ratio of the purified PVA film as the measurement object ( 13 C / 12 C ratio), [( 13 C / 12 C) PDB ] represents the carbon isotope ratio of PDB as a standard substance ( 13 C / 12 C ratio).

[0140] [Measurement of ethylene unit content, alkoxy content, 1,2-glycol bond content and saponification degree of PVA in PVA film]

[0141] After dissolving the PVA obtained in the above [Purification of PVA film] in dimethyl sulfoxide (DMSO-d6), the solution was added to acetone to precipitate the PVA, thereby further purifying it. 1 to 2 drops of trifluoroacetic acid (TFA) were added to the DMSO-d6 solution of the PVA, and the obtained sample was immediately subjected to NMR measurement under the following conditions. From the obtained NMR spectrum, the ethylene unit content, alkoxy content, 1,2-glycol bond content and saponification degree of the PVA in the PVA film were determined.

[0142] (NMR measurement conditions)

[0143] Device used: Lambda500 superconducting nuclear magnetic resonance device manufactured by JEOL Ltd.

[0144] Solvent: DMSO-d6 (TFA added dropwise)

[0145] Concentration: 5% by mass

[0146] Temperature: 80℃

[0147] Resonance frequency: 1H 500MHz

[0148] Flip angle: 45°

[0149] Pulse delay time: 4.0 seconds

[0150] Cumulative times: 6000 times

[0151] [Determination of the stretching limit temperature of PVA film]

[0152] A rectangular test piece with a width of 30 mm and a flow direction of 60 mm is collected from the central part of the width direction of the PVA film roll obtained in the following examples or comparative examples. After the test piece is mounted on a tensile testing machine with a chuck interval of 15 mm, it is stretched in a constant temperature water bath set to a specified temperature, and the stretch ratio at break is measured. Repeat this operation 3 times to find the average value of the stretch ratio at break. If the average value is 6.5 times or more, lower the temperature of the constant temperature water bath by 1°C. If it is lower than 6.5 times, increase the temperature of the constant temperature water bath by 1°C, and find the temperature at which the average value of the stretch ratio at break becomes more than 6.5 times (the lowest temperature at which the average value becomes more than 6.5 times).

[0153] [Evaluation of the number of foreign matter in polarizing film]

[0154] The polarizing film obtained in the following examples or comparative examples was rolled out and cut into a size of 30 cm in the length direction (stretching direction) and 20 cm in the width direction. The blue foreign matter on the surface of the cut polarizing film was visually observed, and the number of foreign matter with the longest diameter of 5 to 500 μm (pieces / 600 cm) was calculated. 2 Repeat this operation 3 times and calculate the average number of foreign matter (pieces / 600cm 2 ). The longest diameter of the foreign matter was measured using a differential interference microscope (magnification: 200 times). It should be noted that in the following examples or comparative examples, the polarizing film after drying was continuously rolled up for 6 hours, so the cut polarizing film became a sample about 6 hours after the start of the production of the polarizing film.

[0155] [Measurement of polarization degree of polarizing film]

[0156] The polarizing film obtained in the following examples or comparative examples is rolled out and cut into a size of 30 cm in the length direction (stretching direction) and 20 cm in the width direction. Two square samples of 1.5 cm in the length direction (stretching direction) and 1.5 cm in the width direction of the polarizing film are collected from the central part of the width direction of the cut polarizing film. The transmittance (Y∥) of the light when overlapping in a parallel manner in the length direction (stretching direction) and the transmittance (Y⊥) of the light when overlapping in a perpendicular manner in the length direction (stretching direction) are measured by the same method as the above transmittance measurement method, and the polarization degree (V) (%) is calculated by the following formula.

[0157] Polarization degree (V) (%) = {(Y∥-Y⊥) / (Y∥+Y⊥)}1 / 2×100

[0158] <Example 1>

[0159] (1) Synthesis of vinyl acetate

[0160] A silica spherical carrier "HSV-I" (manufactured by Shanghai Haiyuan Chemical Technology Co., Ltd.) (spherical diameter 5 mm, specific surface area 160 m2) 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 having a water absorption capacity equivalent to that of the carrier. 2 / g, water absorption rate 0.75g / g) 23g (water absorption 19.7g), immersed in an aqueous solution containing 2.5g of sodium metasilicate 9hydrate 40mL, and let it stand for 20 hours. Then, add 3.3mL of 52wt% hydrazine hydrate aqueous solution, let it stand for 4 hours at room temperature, wash with water until the chloride ions disappear in the water, and dry at 110°C for 4 hours. The obtained palladium / gold / carrier composition is immersed in 60mL of 1.7wt% acetic acid aqueous solution and let it stand for 16 hours. Then, wash with water for 16 hours and dry at 110°C for 4 hours. After that, impregnate it with 2g of potassium acetate in an aqueous solution equivalent to the water absorption of the carrier, and dry it at 110°C for 4 hours to obtain a vinyl acetate synthesis catalyst.

[0161] 3 mL of the obtained catalyst was diluted with 75 mL of glass beads and filled into a SUS316L reaction tube (inner diameter 22 mm, length 480 mm), and a gas mixed in a ratio of ethylene / oxygen / water / acetic acid / nitrogen = 47.3 / 6.1 / 5.6 / 26.3 / 14.7 (mol%) was passed at a reaction temperature of 150° C. and a reaction pressure of 0.6 MPaG at a flow rate of 20 NL / hour to carry out the reaction. Bioethylene derived from sugar cane (manufactured by Braskem SA) was used as ethylene. The reaction gas containing the obtained vinyl acetate was purified to obtain vinyl acetate.

[0162] (2) Synthesis of PVA

[0163] Using the vinyl acetate obtained above as a monomer, using 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile) as a polymerization initiator, using methanol as a solvent, after polymerization at a polymerization temperature of 60°C by a known method, 2 mol of 2,4-diphenyl-4-methyl-1-pentene (DPMP) as a compound with a molecular weight of 1000 or less having a conjugated double bond is added to each mol of the polymerization initiator used. The polymerization time is adjusted according to the target degree of polymerization. In the obtained methanol solution of polyvinyl acetate, a 6% by mass methanol solution of sodium hydroxide is added under stirring in such a manner that the molar ratio of sodium hydroxide to the vinyl acetate unit of polyvinyl acetate becomes 0.023, and a saponification reaction is started at 30°C. As the saponification reaction proceeds, a gel is generated. The gel was crushed at the moment of 50 minutes from the start of the saponification reaction and PVA (PVA-1) swollen with methanol was obtained. The PVA-1 was washed with methanol in an amount five times its mass, and then dried with hot air at 55° C. for 1 hour and with hot air at 100° C. for 2 hours.

[0164] (3) Manufacturing of PVA film and PVA film roll

[0165] An aqueous solution containing 100 parts by mass of the obtained PVA-1, 12 parts by mass of glycerol, and 0.1 parts by mass of lauric acid diethanolamide (PVA concentration: 15% by mass) was adjusted as a film-making stock solution for a PVA film. The film-making stock solution was discharged from a slit die onto a first metal roll with a diameter of 2 m whose surface temperature was adjusted to 90°C and dried, and a film with a moisture content of 12% was peeled off from the metal roll. Then, a second metal roll with a diameter of 1 m and a surface temperature of 70°C was brought into contact with the film surface that was not in contact with the first metal roll and dried. Further, the film was brought into contact with the third to sixth metal rolls (surface temperature of 80 to 120°C, diameter of 1 m) in sequence in a manner that one side and the other side of the film were alternately brought into contact with the metal rolls and dried, and then wound up to obtain a roll of a PVA film (PVA film roll) with a width of 0.6 m, a length of 1000 m, and a thickness of 30 μm.

[0166] (4) Manufacturing of polarizing films

[0167] The obtained PVA film roll is unrolled, and swelling treatment, dyeing treatment, cross-linking treatment, stretching treatment, cleaning treatment, and drying treatment are sequentially performed to continuously manufacture polarizing film. The PVA film is immersed in a swelling treatment tank containing a treatment solution (pure water) at 30°C, during which the film is uniaxially stretched to 1.72 times in the length direction, thereby performing swelling treatment. The PVA film is immersed in a swelling treatment tank containing a treatment solution (2.8% by mass of boric acid and 5% by mass of potassium iodide aqueous solution) at 32°C, during which the film is uniaxially stretched to 1.37 times in the length direction, thereby performing dyeing treatment. The PVA film is immersed in a swelling treatment tank containing a cross-linking treatment solution (2.6% by mass of boric acid aqueous solution) at 32°C, during which the film is uniaxially stretched to 1.12 times in the length direction, thereby performing cross-linking treatment. The PVA film was stretched uniaxially to 2.31 times in the length direction in a swelling treatment tank 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 PVA film was immersed in a cleaning treatment tank containing a cleaning 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 to perform a cleaning treatment. The PVA film was dried at 60°C for 1.5 minutes to perform a drying treatment. Here, the PVA film was not stretched during the cleaning treatment and the drying treatment. In this way, the obtained PVA film was rolled out to continuously manufacture a polarizing film.

[0168] (5) Manufacturing of polarizing film rolls

[0169] Two square samples of the polarizing film with a length direction (stretching direction) of 1.5 cm and a width direction of 1.5 cm were collected from the central part of the width direction of the polarizing film. A spectrophotometer V-7100 (with an integrating sphere) manufactured by Hitachi, Ltd. was used to perform field sensitivity correction for the visible light region with a C light source and a 2-degree field of view in accordance with JIS Z8722 (method for measuring object color). For one polarizing film sample, the transmittance of light when inclined at 45 degrees relative to the stretching axis direction and the transmittance of light when inclined at -45 degrees were measured, and their average value (Y1) was calculated.

[0170] For another polarizing film sample, the transmittance of light at an inclination of 45 degrees and the transmittance of light at an inclination of -45 degrees were measured in the same manner as above, and their average value (Y2) was obtained. The average of Y1 and Y2 obtained above was taken as the transmittance (Y) (%) of the polarizing film.

[0171] The concentrations of iodine and potassium iodide in the swelling treatment tank were adjusted so that the transmittance became 43.5%, and the polarizing film after the drying treatment was continuously wound up for 6 hours to obtain a roll of polarizing film (polarizing film roll).

[0172] The PVA film roll and polarizing film roll thus obtained were measured and evaluated by the above-mentioned methods. The results of the measurements and evaluations are shown in Table 2. In addition, the raw materials and polymerization conditions of PVA are shown in Table 1.

[0173] <Example 2>

[0174] PVA (PVA-2) was obtained in the same manner as in Example 1 except that the polymerization initiator used in the above "(2) Synthesis of PVA" was changed to azobisisobutyronitrile. Then, a PVA film roll and a polarizing film roll were manufactured in the same manner as in Example 1 except that PVA-2 was used, and measurements and evaluations were performed. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0175] <Example 3>

[0176] In the above "(2) Synthesis of PVA", PVA (PVA-3) was obtained in the same manner as in Example 1 except that the polymerization temperature of PVA was changed to 90°C. Then, using PVA-3, a PVA film roll and a polarizing film roll were manufactured in the same manner as in Example 1 except that the polymerization temperature of PVA was changed to 90°C, and measurements and evaluations were performed. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0177] <Comparative Example 1>

[0178] 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 changed to petroleum-derived ethylene (manufactured by AirLiquide Kogyo Gas Ltd.). Then, a PVA film roll and a polarizing film roll were produced in the same manner as in Example 1 except that PVA-4 was used, and measurements and evaluations were performed. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0179] <Example 4>

[0180] The PVA used in the above "(3) Production of PVA film and PVA film roll" was changed to a PVA obtained by mixing PVA-4 obtained in Comparative Example 1 and PVA-1 obtained in Example 1 at a mass ratio of 1:1. A PVA film roll and a polarizing film roll were produced in the same manner as in Example 1, and measurements and evaluations were performed. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0181] <Example 5>

[0182] As the monomer used in the above-mentioned "(2) Synthesis of PVA", 5.7 parts by mass of bioethylene derived from sugar cane (manufactured by Braskem SA) was added to 100 parts by mass of vinyl acetate, and the pressure in the reaction vessel was maintained at 0.03 MPaG to carry out the polymerization reaction. PVA (PVA-5) was obtained in the same manner as in Example 1. Then, using PVA-5, a PVA film roll and a polarizing film roll were manufactured in the same manner as in Example 1, and measurements and evaluations were carried out. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0183] <Example 6>

[0184] Rice, a C3 plant, is subjected to an alkali treatment step, a saccharification step, and an ethanolation step to obtain rice-derived ethanol, and the ethanol is subjected to a dehydration reaction at 190° C. using mordenite as a catalyst to produce rice-derived bioethylene.

[0185] Then, 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 changed to the bioethylene derived from the rice. Then, a PVA film roll and a polarizing film roll were manufactured in the same manner as in Example 1 except that PVA-6 was used, and measurements and evaluations were performed. The results of the measurements and evaluations are shown in Table 2. It should be noted that the raw materials and polymerization conditions of PVA are shown in Table 1.

[0186] [Table 1]

[0187]

[0188] *1)AMV: 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile)

[0189] AIBN: Azobisisobutyronitrile

[0190] *2) Mass relative to 100 parts by mass of vinyl acetate [Table 2]

[0191]

Claims

1. An optical film using a polyvinyl alcohol resin film, wherein the polyvinyl alcohol resin film is a polyvinyl alcohol resin film comprising a polyvinyl alcohol resin (A), wherein carbon 14 ( 14 C) existence ratio 14 C / C is 1.0×10 -14 Above, among them, The polyvinyl alcohol resin (A) does not contain an alkoxy group, does not contain an ethylene unit, has a saponification degree of 80 mol% or more, a polymerization degree of 200 or more and less than 8000, and a 1,2-glycol bond content of 0.2 mol% or more and less than 2.0 mol%.

2. The optical film according to claim 1, wherein: The carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is above -20‰.

3. The optical film according to claim 1, wherein: The carbon 13 ( 13 C) carbon stable isotope ratio δ 13 C is lower than -20‰.

4. The optical film according to any one of claims 1 to 3, wherein The polyvinyl alcohol resin (A) has a 1,2-glycol bond content of 0.4 mol % or more and 1.4 mol % or less.

5. The optical film according to any one of claims 1 to 3, wherein The polyvinyl alcohol resin (A) has a 1,2-glycol bond content of 0.6 mol % or more and 1.4 mol % or less.

6. The optical film according to any one of claims 1 to 3, wherein All or part of the polyvinyl alcohol resin (A) is a polyvinyl alcohol resin (Ab) in which all or part of carbon is derived from ethylene (Bb) derived from biological sources.

7. The optical film according to any one of claims 1 to 3, wherein The carbon 14 ( 14 C) existence ratio 14 C / C is 5.0×10 -14 above.

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