Vinyl acetate, vinyl acetate polymer, and vinyl alcohol polymer

Abstract

To provide traceable vinyl acetate, a polymer containing the vinyl acetate, and a vinyl alcohol polymer which is a saponified product of the polymer.SOLUTION: The vinyl acetate having ≥ 1.0 * 10 - 14 ratio of carbon 14 to the total carbon, the vinyl acetate polymer containing the vinyl acetate as a monomer unit and the vinyl alcohol polymer obtained by saponifying the vinyl acetate polymer are provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to traceable vinyl acetate, polymers containing said vinyl acetate as a monomer unit, and saponified products thereof. [Background technology]

[0002] Vinyl acetate is used as a raw material for vinyl acetate resins and vinyl alcohol resins, and also as a copolymerization monomer with ethylene, styrene, acrylates, methacrylates, etc. The resulting resins and copolymers are important industrial materials used in a wide range of fields, including paints, adhesives, and textile processing agents.

[0003] Among these, vinyl alcohol polymer (hereinafter sometimes referred to as PVOH), which is obtained by polymerizing vinyl acetate and then saponifying the resulting polymer, is one of the few crystalline water-soluble polymers. Taking advantage of its excellent water solubility and film properties (strength, oil resistance, film-forming ability, oxygen gas barrier properties, etc.), it is widely used in emulsifiers, suspending agents, surfactants, various binders, adhesives, fiber processing agents, paper processing agents, films, fibers, fabrics, etc.

[0004] Ethylene-vinyl alcohol copolymers (hereinafter sometimes referred to as EVOH) obtained by copolymerizing vinyl acetate and ethylene and then saponifying the resulting copolymer have excellent transparency, gas barrier properties such as oxygen, aroma retention, solvent resistance, oil resistance, antistatic properties, and mechanical strength. Taking advantage of these properties, EVOH is widely used in a variety of packaging containers, including food packaging containers, pharmaceutical packaging containers, industrial chemical packaging containers, and pesticide packaging containers. To produce such molded products, secondary processing is often performed after melt molding of the ethylene-vinyl alcohol copolymer. For example, stretching to improve mechanical strength and thermoforming of a multilayer sheet containing an ethylene-vinyl alcohol copolymer layer to form a container shape are commonly used.

[0005] As vinyl alcohol polymers and ethylene-vinyl alcohol copolymers are used in a wide range of applications, it is the responsibility of suppliers to supply high-quality products to the market. In addition, there is a need for a method to distinguish one's own products from those of other companies for branding purposes.

[0006] For example, the ethylene-vinyl alcohol copolymer used in the gas barrier layer of commercially available packaging containers is formed into the packaging container by thermoforming. However, the thermal history of the thermoforming process can cause the ethylene-vinyl alcohol copolymer to form a gel that is insoluble in solvents. Therefore, even if the packaging container is recovered and the ethylene-vinyl alcohol copolymer used is extracted with a solvent and its molecular weight is measured, it is often difficult to accurately measure the molecular weight. Therefore, it is not possible to determine whether the ethylene-vinyl alcohol copolymer is a company's own ethylene-vinyl alcohol copolymer simply by analyzing the molded product.

[0007] Therefore, when the produced vinyl acetate and its resulting polymers and copolymers, as well as their saponification products, are used through many distribution channels to produce paints, adhesives, fiber processing agents, paper processing agents, films, fibers, fabrics, food packaging containers, pharmaceutical packaging containers, industrial chemical packaging containers, agricultural chemical packaging containers, etc., and then discarded, it is difficult to determine which factory or production line produced the resin or its used packaging containers. It is also difficult to investigate the quality of a company's own products during or after use, or to track their impact on the environment and their decomposition in the ground after disposal.

[0008] One method for tracking one's own products is to add a tracer substance to the vinyl alcohol polymer, but adding a tracer can increase costs and reduce the performance of the vinyl alcohol polymer. Summary of the Invention [Problem to be solved by the invention]

[0009] The inventors focused on the carbon isotopes contained in vinyl acetate and discovered that by using vinyl acetate containing a certain amount of a specific carbon isotope, it is possible to trace the resulting polymers and copolymers, and even if the final product is discarded, it is possible to determine whether the raw materials are from the same company.

[0010] That is, an object of the present invention is to provide traceable vinyl acetate, a polymer containing said vinyl acetate as a monomer unit, and a vinyl alcohol polymer which is a saponified product thereof. [Means for solving the problem]

[0011] The present invention provides the following vinyl acetate, a polymer containing said vinyl acetate as a monomer unit, and a saponified product thereof.

[0012] [1] The ratio of carbon-14 to total carbon is 1.0 × 10 -14 That's all vinyl acetate.

[0013] [2]

[0023] The vinyl acetate according to [1] above, having a stable carbon isotope ratio of -20‰ or more.

[0014] [3]

[0023] The vinyl acetate according to [1] above, having a stable carbon isotope ratio of less than -20‰.

[0015] [4] The vinyl acetate according to any one of [1] to [3] above, which contains a sulfur content of more than 0 ppm to 100 ppm or less. [5] [4] Vinyl acetate according to the above [4], wherein the sulfur component is dimethyl sulfide or dimethyl sulfoxide.

[0016] [6] [6] The vinyl acetate according to any one of [1] to [5] above, containing 10 ppm to 1,500 ppm of acetate ester.

[0017] [7] The vinyl acetate according to [6] above, wherein the acetate ester is at least one of methyl acetate and ethyl acetate.

[0018] [8] The vinyl acetate according to any one of [1] to [7] above, containing a polymerization inhibitor in an amount of more than 0 ppm to 100 ppm or less.

[0019] [9] The vinyl acetate according to any one of [1] to [8] above, which contains 1 ppm to 500 ppm of at least one compound selected from polycarboxylic acids, hydroxycarboxylic acids, and hydroxylactone compounds.

[0020]

[10] The vinyl acetate according to any one of [1] to [9] above, which contains 0.001 to 10 parts by mass of acetaldehyde dimethyl acetal.

[0021]

[11] A vinyl acetate polymer containing the vinyl acetate according to any one of [1] to

[10] above as a monomer unit.

[0022]

[12] A vinyl alcohol polymer obtained by saponifying the vinyl acetate polymer described in

[11] above.

[0023]

[13] The vinyl alcohol polymer according to

[12] above, further containing ethylene units, the content of which is 1 mol % or more and 60 mol % or less.

[0024]

[14] The vinyl alcohol polymer according to

[12] or

[13] above, which has a degree of saponification of 80 mol % or more.

[0025]

[15] The vinyl alcohol polymer according to any one of

[12] to

[14] above, having a viscosity-average degree of polymerization of 200 or more and 5,000 or less.

[0026]

[16] The vinyl alcohol polymer according to any one of

[12] to

[15] above, wherein the content of 1,2-glycol bonds is 0.2 mol % or more and 2 mol % or less.

[0027]

[17] The ratio of carbon-14 to total carbon is 1.0 × 10 -14 The vinyl alcohol polymer according to any one of

[12] to

[16] above.

[0028]

[18] The vinyl alcohol polymer according to any one of

[12] to

[17] above, having a stable carbon isotope ratio of -20‰ or more.

[0029]

[19] The vinyl alcohol polymer according to any one of

[12] to

[17] above, having a stable carbon isotope ratio of less than -20‰.

[0030]

[20] The vinyl alcohol polymer according to any one of

[12] to

[19] above, which contains a sulfur content of more than 0 ppm and not more than 100 ppm. [twenty one] The vinyl alcohol polymer according to

[20] above, wherein the sulfur component is dimethyl sulfide or dimethyl sulfoxide.

[0031] [twenty two] The ethylene unit content is 1 mol% or more and 15 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The vinyl alcohol polymer according to any one of

[12] to

[21] above, which has propyl groups at the polymer terminals, and the content of the propyl groups relative to all monomer units is 0.0005 mol % or more and 0.1 mol % or less.

[0032] [twenty three] The vinyl alcohol polymer according to any one of

[12] to

[22] above, which has alkoxy groups at polymer terminals, and the content of the alkoxy groups relative to all monomer units is 0.0005 mol % or more and 1 mol % or less.

[0033] [twenty four] The vinyl alcohol polymer according to any one of

[12] to

[23] above, having the following Structure (I) and Structure (II) at the polymer terminals, and the total content of Structure (I) and Structure (II) relative to all monomer units constituting the vinyl alcohol polymer is 0.001 mol % or more and 0.1 mol % or less.

[0034] [ka] (wherein Y is a hydrogen atom or a methyl group).

[0035] [ka] (wherein Z is a hydrogen atom or a methyl group).

[0036] [twenty five] The ethylene unit content is 1 mol% or more and 15 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The molar ratio R[I / (I+II)] of the structure (I) to the sum of the structure (I) and the structure (II) is expressed by the following formula (1): R<0.92-Et / 100 (1) The vinyl alcohol polymer according to

[24] above, which satisfies the above. (In formula (1), Et is the ethylene unit content (mol %).)

[0037]

[26] The vinyl alcohol polymer according to any one of

[13] ,

[22] and

[25] above, wherein the block character of the ethylene unit is 0.90 to 0.99.

[0038]

[27] The ethylene unit content is 15 mol% or more and 60 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The total content of the structure (I) and the structure (II) is 0.002 mol % or more and 0.02 mol % or less with respect to all monomer units constituting the vinyl alcohol polymer, and the molar ratio R [I / (I+II)] of the structure (I) to the total of the structure (I) and the structure (II) is expressed using the ethylene unit content Et in the vinyl alcohol polymer, and is expressed by the following formula (2): 0.8 <R+Et / 100 (2) The vinyl alcohol polymer according to either

[24] or

[25] above, which satisfies the above.

[0039]

[28] The ratio of carbon-14 to total carbon is 1.0 × 10 -14 This is the method for tracking a polymer using vinyl acetate.

[0040]

[29] The method for tracking a polymer using vinyl acetate according to

[28] above, wherein the carbon stable isotope ratio of vinyl acetate is −20‰ or more.

[0041]

[30] The method for tracking a polymer using vinyl acetate according to

[28] above, wherein the carbon stable isotope ratio of vinyl acetate is less than -20‰.

[0042]

[31] A method for tracking a polymer using a vinyl acetate polymer containing the vinyl acetate according to any one of

[28] to

[30] as a monomer unit.

[0043]

[32] A method for tracking a polymer using a vinyl alcohol polymer obtained by saponifying the vinyl acetate polymer described in

[31] above. [Effects of the Invention]

[0044] According to the present invention, it is possible to provide traceable vinyl acetate, a polymer containing said vinyl acetate, and a vinyl alcohol polymer of said saponified product. [Brief explanation of the drawings]

[0045] [Figure 1] FIG. 1 is a schematic diagram of a polymerization apparatus used in Example 46. [Figure 2] FIG. 1 is a schematic diagram of the stirring blade used in Example 46. DETAILED DESCRIPTION OF THE INVENTION

[0046] Vinyl acetate according to the present invention, a vinyl acetate polymer obtained by polymerizing vinyl acetate, and a vinyl alcohol polymer which is a saponified product thereof will be described in detail below.

[0047] In vinyl acetate obtained from conventional petroleum feedstocks, the ratio of carbon atoms to total carbon atoms is 14 (hereinafter, 14 C) ratio (hereinafter, 14 C / C) is 1.0 × 10 -14 Whereas the vinyl acetate of the present invention is 14 C / C is 1.0×10 -14 That's it. Total carbon refers to carbon including all carbon isotopes.

[0048] From the perspective of ease of tracking, 14 C / C is 1.0 x 10 -13 It is preferable that the value is 5.0×10 or more. -13 It is more preferable that the content is equal to or greater than 100% by mass of non-fossil raw materials. 14 The upper limit of C / C is 1.2×10 -12 However, if necessary, a blank natural product such as an oxalic acid standard may be used. 14 The C / C may be actually measured and the value may be used as the upper limit.

[0049] As mentioned above 14 One possible method for controlling the C / C range is to use vinyl acetate derived from natural products, as described below. Artificial carbon-14 exists in nature, and the carbon-14 concentration in natural products fluctuates over time. Therefore, when using vinyl acetate derived from natural products, the carbon-14 concentration in the natural product must be appropriately corrected to control the carbon content of the vinyl acetate. 14The C / C can be calculated. The half-life of carbon-14 is 5,730 years, but considering the time it takes for a typical chemical product to be released to the market, the decrease in the amount of carbon-14 can be ignored.

[0050] Carbon 13 (hereinafter, 13 To quantify carbon-12 ions (sometimes referred to as C) and carbon-14, the target vinyl acetate is burned to produce carbon dioxide, and then carbon dioxide or its reduced form, graphite, is analyzed by accelerator mass spectrometry (AMS). For example, graphite is ionized by irradiating it with a Cs beam, and the amounts of carbon-12 ions, carbon-13 ions, and carbon-14 ions are measured.

[0051] 14 The C / C ratio can be determined by converting the material to carbon dioxide or graphite as described above and then measuring the carbon-14 content using accelerator mass spectrometry, for example, by comparing it with the carbon-14 content in oxalic acid, a standard substance prepared by the National Institute of Standards and Technology.

[0052] The vinyl acetate can be synthesized, for example, as follows. Vinyl acetate can usually be obtained by the gas-phase reaction of ethylene, acetic acid, and oxygen in the presence of a catalyst. Vinyl acetate containing a predetermined amount of carbon-14 can be obtained by using ethylene or acetic acid containing a predetermined amount of carbon-14 in either or both of the ethylene and acetic acid. Examples of ethylene and acetic acid containing a predetermined amount of carbon-14 include ethylene and acetic acid derived from biomass.

[0053] The biomass is a non-exhaustible industrial resource originating from living organisms, and is a renewable organic resource derived from living organisms, excluding fossil resources.

[0054] Biomass absorbs carbon dioxide from the atmosphere through photosynthesis during its growth process. Therefore, even if biomass is burned and carbon dioxide is emitted, the amount of carbon dioxide in the atmosphere does not increase overall. This property is called carbon neutral, and from the perspective of the global environment, it is preferable to use ethylene and / or acetic acid derived from biomass.

[0055] Biomass may be of a single origin or a mixture, and examples include cellulosic crops such as pulp, kenaf, wheat straw, rice straw, waste paper, and papermaking residues; oils and fats such as rapeseed oil, cottonseed oil, soybean oil, coconut oil, and castor oil; carbohydrate crops such as corn, potatoes, wheat, rice, rice husks, rice bran, used rice, cassava, and sago palm; essential oils such as pine oil, orange oil, and eucalyptus oil; wood, charcoal, compost, natural rubber, cotton, sugarcane, soybean pulp refuse, bagasse, buckwheat, soybeans, black pulp liquor, and vegetable oil cakes. Biomass is not limited to biofuel harvests, but also includes agricultural residues, urban waste, industrial waste, paper industry sediments, pasture waste, and wood and forest waste.

[0056] The biomass-derived carbon refers to carbon that exists in the atmosphere as carbon dioxide, which is taken up by plants and then synthesized using this as a raw material. Since the atmosphere contains a certain amount of carbon-14, ethylene and acetic acid derived from biomass that has taken in carbon dioxide from the atmosphere will contain a certain amount of carbon-14. Typically, biomass-derived ethylene and acetic acid contain 1.0 x 10 carbon-14 relative to the total carbon. -12 It contains a higher proportion of carbon-14.

[0057] On the other hand, fossil fuels such as petroleum contain almost no carbon-14, and the ratio of carbon-14 to total carbon in ethylene and acetic acid derived from fossil fuels is 1.0 × 10 -14 Therefore, by using both biomass-derived ethylene and acetic acid and fossil-derived ethylene and acetic acid as raw materials for vinyl acetate, the obtained vinyl acetate 14The C / C ratio can be adjusted to the desired value. For example, vinyl acetate obtained from biomass-derived ethylene and biomass-derived acetic acid and vinyl acetate obtained from fossil resource-derived ethylene and fossil resource-derived acetic acid can be 14 They may be mixed so that the C / C ratio is a desired value, or vinyl acetate may be obtained by using biomass-derived ethylene and / or acetic acid and fossil resource-derived ethylene and / or acetic acid in a desired ratio.

[0058] In addition, carbon 12 (hereinafter, 12 While the molecular weight of ethylene derived from ethylene (often referred to as "C") is 28.05 and the molecular weight of acetic acid is 60.05, ethylene and acetic acid containing large amounts of carbon-13 or carbon-14 have larger molecular weights. Therefore, the boiling point of ethylene is slightly higher than that of acetic acid, which typically has a boiling point of -103.7°C and 117.9°C, respectively. By utilizing this difference in boiling point resulting from the molecular weight ratio, i.e., the lower the molecular weight, the lower the boiling point, the more carbon-13 or carbon-14 the ethylene or acetic acid will have. Specifically, the desired carbon-13 or carbon-14 content can be achieved by distilling and refining ethanol, the raw material for ethylene and acetic acid, ethylene obtained by the dehydration reaction of ethanol, and acetic acid obtained by the oxidation reaction of ethanol, or by vaporizing the ethanol during the vapor-phase dehydration or vapor-phase oxidation.

[0059] By adjusting the carbon-14 content of vinyl acetate to the above range, it can be distinguished from ordinary vinyl acetate obtained from petroleum-derived ethylene. 14 By changing the C / C ratio, it is possible to determine what products the vinyl acetate of the present invention was used in, even from the recovered waste. Therefore, the vinyl acetate of the present invention can be traced after production.

[0060] In addition to setting the carbon-14 ratio of vinyl acetate within the above range, from the viewpoint of improving the accuracy of tracking, the carbon stable isotope ratio (hereinafter, δ 13 It is preferable that the temperature (C) is within a specific range.

[0061] The stable carbon isotope ratio refers to the ratio of carbon-13 to carbon-12 among the three isotopes of carbon atoms that exist in nature: carbon-12, carbon-13, and carbon-14. The stable carbon isotope ratio is expressed as a deviation from a standard substance, and is a value (δ value) defined by the following formula (3):

[0062] [Number 1] δ 13 C[‰]={( 13 C / 12 C) sample / ( 13 C / 12 C) PDB -1.0}×1,000 (3)

[0063] Here, [( 13 C / 12 C) sample ] represents the stable isotope ratio of the measurement target, and [( 13 C / 12 C) PDB ] indicates the stable isotope ratio of the standard material. The subscript PDB is an abbreviation for "Pee Dee Belemnite," which refers to a fossil arrowhead made of calcium carbonate (the standard material is a fossil arrowhead excavated from the Pee Dee Formation in South Carolina). 13 C / 12 It is also used as a standard for stable carbon isotope ratios (δ 13 C) is measured by accelerator mass spectrometry. Because standard materials are rare, it is also possible to use a working standard with a known stable isotope ratio relative to the standard material.

[0064] Said δ 13 By using vinyl acetate with a C of -20‰ or more, or vinyl acetate with a C of less than -20‰, tracking accuracy can be further improved. 13 A simple method for adjusting C to the above range is to use the above-mentioned biomass-derived ethylene or acetic acid.

[0065] When using ethylene and acetic acid derived from biomass, as will be described later, biomass can be broadly divided into C3 plants such as sweet potato, sugar beet, rice, trees, and algae, and C4 plants such as corn, sugarcane, and cassava. 13 C is different.

[0066] 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 (Crassulacean Acid Metabolism) plants (hereinafter referred to as CAM plants).

[0067] More than 90% of plants on Earth belong to the C3 category, including agriculturally useful plants such as rice, wheat, 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, by extension, the photosynthetic reaction. Plants that only have this Calvin-Benson cycle are called C3 plants.

[0068] δ 13 When C is to be less than -20‰, these C3 plants and their mixtures are widely used as carbon sources, but rice, wheat, potato, and palm oil are preferred as carbon sources in terms of production volume and cost.

[0069] When using biomass derived from C3 plants, the carbon stable isotope ratio (δ 13 C) is preferably from -60 to less than -20‰, more preferably from -50 to -22‰, even more preferably from -45 to -25‰, and particularly preferably from -40 to -26‰, from the viewpoint of improving the tracking accuracy of polymers using vinyl acetate, etc.

[0070] 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. C4 plants can efficiently fix carbon dioxide. Furthermore, while C3 plants have difficulty collecting carbon dioxide at high temperatures, C4 plants do not. Furthermore, photosynthesis can be performed efficiently even with limited water. This 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.

[0071] δ 13 When C is to be -20‰ or higher, these C4 plants and their mixtures are widely used as carbon sources, but corn, sugarcane, and cassava are preferred as carbon sources in terms of production volume and cost.

[0072] CAM plants have a photosynthetic system adapted to dry environments, and this photosynthetic system is thought to be an evolved form of C3 photosynthesis. Examples of CAM plants include cacti (Cactaceae), safflowers (Crassulaceae), and euphorbiaceae (Euphorbiaceae). The stable carbon isotope ratios of CAM plants are generally in the range of -35‰ to -10‰, and these CAM plants can be used as raw materials, or in combination if necessary.

[0073] As mentioned above, the δ 13 C is mainly the δ 13 Since it depends on C, ethylene and / or acetic acid with different carbon isotope ratios can be appropriately mixed to obtain the δ 13For example, vinyl acetate can be produced using ethylene and / or acetic acid derived from biomass of C4 plants and C3 plants, and the two can be mixed in a predetermined ratio to produce vinyl acetate. 14 along with the value of C 13 The value of C can be adjusted appropriately.

[0074] Although vinyl acetate polymers and their saponified products contain trace amounts of crosslinking agents, additives, graft components, etc., as needed, the main component of the carbon source constituting these vinyl acetate polymers and their saponified products is usually 65% ​​by mass or more derived from vinyl acetate, so the δ 13 C and 14 By controlling the C / C ratio, the δ of the vinyl acetate polymer and its saponification product obtained from the vinyl acetate can be controlled. 13 C and 14 C / C can be controlled.

[0075] In addition, the vinyl acetate of the present invention 14 C / C, δ if necessary 13 C is in the above range, 14 C / C and δ 13 Vinyl acetate having C may be used in combination.

[0076] For example, a predetermined δ 13 Not only do we obtain vinyl acetate that exhibits a C but also a different δ 13 C vinyl acetate is mixed to obtain a predetermined δ 13 C, i.e., δ that cannot be achieved by C3 plants alone. 13 Including C, more specific δ 13 By using a different δ 13 When a C raw material is used, the statistical analysis value obtained by analyzing its carbon stable isotope ratio is unique, making it possible to distinguish it from other raw materials. Therefore, the δ 13 C also has a unique analytical value, making it easy to identify and track.

[0077] Different δ 13 When a mixture of vinyl acetates having C is used, they may be mixed at the stage of purified vinyl acetate as the final product, or crude vinyl acetates may be mixed at the previous stage and then purified by distillation. Also, different ethylene and / or acetic acids may be mixed and then reacted to produce vinyl acetate.

[0078] Among these, from the viewpoints of adjusting trace components and diversifying raw materials, and also from the viewpoint of further increasing the traceability of the resulting vinyl acetate polymer and its saponified product, a method using multiple raw material sources, both fossil and non-fossil, for the vinyl acetate is preferred. The mixing ratio in the production method may be constant or may be changed over time or for each vinyl acetate polymer and its saponified product.

[0079] In addition, since the vinyl acetate is neither 100% derived from fossil materials nor 100% derived from non-fossil materials, the resulting vinyl acetate polymer and its saponification products are unique and specific. 14 The ratio of non-fossil raw materials to fossil raw materials is as follows: 14 It can be identified by quantifying C / C.

[0080] Furthermore, by using multiple raw material sources, both fossil and non-fossil, for vinyl acetate, fluctuations in the raw material costs of the resulting resin can be suppressed. Vinyl acetate polymers and their saponified products obtained from the vinyl acetate are excellent in cost and raw material source stability, making them widely usable. For example, the above-mentioned effects can be further expected by using bioethylene obtained from bioethanol or bionaphtha as the non-fossil raw material for vinyl acetate, and ethylene derived from naphtha as the fossil raw material.

[0081] The vinyl acetate having the specific carbon isotope ratio preferably further contains the following compounds:

[0082] The vinyl acetate of the present invention preferably contains more than 0 ppm but not more than 100 ppm of sulfur. As described above, the vinyl acetate of the present invention can be easily produced by using ethylene and / or acetic acid derived from biomass as raw materials. 14 C / C and δ 13 C can be controlled. When biomass-derived ethylene and / or vinyl acetate is used, vinyl acetate containing organic sulfur compounds derived from biomass is obtained. On the other hand, petroleum-derived vinyl acetate has a lower sulfur content than biomass-derived vinyl acetate because it is desulfurized during naphtha cracking. Therefore, comparing the sulfur content makes it easier to track biomass-derived vinyl acetate and vinyl acetate polymers. In particular, since biomass-derived vinyl acetate and vinyl acetate polymers contain dimethyl sulfide or dimethyl sulfoxide as sulfur, vinyl acetate containing dimethyl sulfide or dimethyl sulfoxide is even easier to track.

[0083] A vinyl alcohol polymer obtained by copolymerizing vinyl acetate and ethylene in the coexistence of an acetate ester and then saponifying the copolymer has improved melt extrusion stability and excellent color, and therefore it is preferred that the vinyl acetate contains an acetate ester.

[0084] When vinyl acetate is polymerized, an ester exchange reaction occurs between vinyl acetate and an aliphatic alcohol having 4 or less carbon atoms, which is used as a polymerization solvent, and the resulting product is reacted with vinyl acetate in the following manner:

[0085] [ka]

[0086] (wherein R is an alkyl group having 4 or less carbon atoms) to produce acetaldehyde. If the acetaldehyde content exceeds 200 ppm, the melt extrusion stability and melt moldability of the vinyl alcohol polymer may deteriorate, and coloring and gelation may occur when the polymer is molded.

[0087] Although the mechanism by which acetaldehyde exerts its adverse effects is not entirely clear, it is believed that acetaldehyde acts as a chain transfer agent during polymerization, affecting the degree of polymerization, polymerization degree distribution, branching, and other properties of the resulting ethylene-vinyl acetate copolymer, resulting in adverse effects on the melt extrusion stability and melt moldability of the ethylene-vinyl alcohol copolymer. Furthermore, acetaldehyde condenses during the polymerization of ethylene and vinyl acetate, converting them into condensates that are prone to coloring and gel formation, and these condensates cannot be removed even in the subsequent purification process of the polymer, resulting in coloring and gel formation when the ethylene-vinyl alcohol copolymer is molded.

[0088] Since the transesterification reaction is an equilibrium reaction, the addition of an acetic acid ester has the effect of suppressing the generation of acetaldehyde.

[0089] As the acetate ester, a saturated acetate ester is preferred from the viewpoints of melt extrusion stability and color. The saturated acetate ester refers to an ester composed of acetic acid and a saturated aliphatic alcohol. As the saturated acetate ester, an ester of acetic acid and an aliphatic alcohol having 4 or less carbon atoms is preferred, and methyl acetate or ethyl acetate is more preferred.

[0090] The content of the acetate ester relative to the vinyl acetate is preferably 10 ppm to 1,500 ppm, more preferably 30 ppm to 1,300 ppm, further preferably 50 ppm to 1,200 ppm, and particularly preferably 100 ppm to 1,000 ppm.

[0091] A mixture of multiple acetate esters may be used. In this case, it is preferable that the total content of the acetate esters is within the above range.

[0092] From the viewpoint of storage stability, the vinyl acetate of the present invention preferably contains a polymerization inhibitor, such as p-benzoquinone, tert-butylhydroquinone, 4-tert-butylpyrocatechol, cupferron, 2,6-di-tert-butyl-4-methylphenol, N,N-diethylhydroxylamine, hydroquinone, p-methoxyphenol, N-nitroso-N-phenylhydroxylamine aluminum, phenothiazine, tert-butylhydroquinone, dibutylhydroxytoluene, 1,1-diphenyl-2-picrylhydrazyl, and mequinol.

[0093] The content of the polymerization inhibitor is preferably more than 0 ppm but not more than 100 ppm, more preferably more than 0 ppm but not more than 50 ppm, even more preferably more than 0 ppm but not more than 30 ppm, and particularly preferably 1 ppm to 30 ppm. A large amount of polymerization inhibitor may slow the polymerization rate or cause discoloration after production, while an excessively small amount may not only reduce the storage stability of vinyl acetate but also slow down the polymerization.

[0094] From the viewpoints of improving the color of the ethylene-vinyl alcohol copolymer obtained by copolymerizing vinyl acetate and ethylene and saponifying the copolymer, and suppressing odor and the occurrence of fish eyes during film formation, the vinyl acetate of the present invention preferably contains at least one of polycarboxylic acid, hydroxycarboxylic acid, and hydroxylactone compound.

[0095] Examples of polycarboxylic acids and hydroxycarboxylic acids include malonic acid, succinic acid, maleic acid, phthalic acid, oxalic acid, glutaric acid, glycolic acid, lactic acid, glycerin, malic acid, tartaric acid, citric acid, and salicylic acid, with citric acid being preferred.

[0096] The hydroxylactone compound is not particularly limited as long as it has a lactone ring and a hydroxyl group in the molecule, and examples thereof include L-ascorbic acid, erythorbic acid, and glucono-delta-lactonic acid, with L-ascorbic acid and erythorbic acid being preferred.

[0097] The content of polycarboxylic acid, hydroxycarboxylic acid and hydroxylactone compound is preferably 1 ppm to 1,000 ppm, more preferably 5 ppm to 500 ppm, and even more preferably 10 ppm to 300 ppm, relative to vinyl acetate. If the content of polycarboxylic acid, hydroxycarboxylic acid and hydroxylactone compound is less than 1 ppm, the above effect is small, and if it exceeds 1,000 ppm, the polymerization of vinyl acetate tends to be inhibited.

[0098] Examples of the polycarboxylic acid, hydroxycarboxylic acid, and hydroxylactone compound include a method in which they are added to vinyl acetate in advance, a method in which they are added to the polymerization system together with vinyl acetate and a solvent all at once, a method in which they are added to the polymerization system as is, a method in which they are dissolved in the solvent used in polymerization in advance and then added to the polymerization system, a method in which they are mixed with other additives in advance and then added, and a method in which they are added in portions.

[0099] From the viewpoints of controlling the variation in the average polymerization degree of the vinyl acetate polymer and the color and solubility of the polyvinyl alcohol obtained by saponification, it is preferred that the vinyl acetate of the present invention contains acetaldehyde dimethyl acetal.

[0100] The content of acetaldehyde dimethyl acetal is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 7 parts by mass, even more preferably 0.1 to 5 parts by mass, and particularly preferably 1 to 5 parts by mass, based on 100 parts by mass of vinyl acetate. If the content of acetaldehyde dimethyl acetal is less than 0.001 part by mass, the above effect is small, whereas if it exceeds 10 parts by mass, the polymerization of vinyl acetate tends to be inhibited.

[0101] Examples of methods for adding acetaldehyde dimethyl acetal include a method in which it is added to vinyl acetate in advance, a method in which it is added to the polymerization system all at once together with vinyl acetate and a polymerization solvent described below, a method in which it is added to the polymerization system as is, a method in which it is dissolved in a solvent to be used in polymerization in advance and then added to the polymerization system, a method in which it is mixed with other additives in advance and then added, and a method in which it is added in portions.

[0102] By polymerizing or copolymerizing the vinyl acetate of the present invention, a vinyl acetate polymer or copolymer (hereinafter, polymer and copolymer will be collectively referred to as polymer) containing vinyl acetate as a monomer can be obtained. In the case of copolymerization, the copolymerized monomer may be any other monomer copolymerizable with vinyl acetate.

[0103] Other copolymerizable monomers include, for example, ethylene; olefins having 3 to 30 carbon atoms such as propylene, 1-butene, and isobutene; acrylic acid or its salts; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; methacrylic acid or its salts; methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate. methacrylic acid esters such as i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylic acids such as acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or a salt thereof, and N-methylolacrylamide or a derivative thereof; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or a salt thereof, methacrylamidepropyldimethylamine or a salt thereof, and N-methylolmethacrylamide or a derivative thereof; 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, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl 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 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.

[0104] In the polymerization of vinyl acetate, it is preferable to use an aliphatic alcohol having 4 or less carbon atoms as the polymerization solvent. When an aliphatic alcohol having 5 or more carbon atoms or an aromatic alcohol is used, the effects of the present invention cannot be fully obtained. Examples of aliphatic alcohols having 4 or less carbon atoms include methanol, ethanol, propanol, and butanol. Among these, methanol, ethanol, and propanol are preferred, methanol and ethanol are more preferred, and methanol is even more preferred.

[0105] As described above, the vinyl acetate of the present invention has a carbon-14 to total carbon ratio of 1.0×10 -14 Therefore, the ratio of carbon-14 to total carbon in the vinyl acetate polymer obtained by polymerizing such vinyl acetate is 1.0 × 10 -14 That's all. When vinyl acetate with a stable carbon isotope ratio of -20‰ or higher is used as vinyl acetate, the stable carbon isotope ratio in the resulting vinyl acetate polymer will be -20‰ or higher. When vinyl acetate with a stable carbon isotope ratio of less than -20‰ is used as vinyl acetate, the stable carbon isotope ratio in the resulting vinyl acetate polymer will be less than -20‰.

[0106] When vinyl acetate contains more than 0 ppm but not more than 100 ppm of sulfur, the resulting vinyl acetate polymer contains more than 0 ppm but not more than 100 ppm of sulfur. As described above, the sulfur contained is preferably dimethyl sulfide or dimethyl sulfoxide, from the viewpoint of ease of tracing.

[0107] The vinyl alcohol polymer is obtained by saponifying the polymer having vinyl acetate as a monomer unit. As mentioned above, the ratio of carbon-14 to total carbon is 1.0 × 10 -14 When a vinyl acetate polymer having a carbon-14 content of 1.0×10 or more is used, the ratio of carbon-14 to total carbon in the resulting vinyl alcohol polymer is 1.0×10 -14 That's all. When a vinyl acetate polymer having a stable carbon isotope ratio of -20‰ or more is used as the vinyl acetate polymer, the carbon isotope ratio in the resulting vinyl alcohol polymer will be -20‰ or more. When a vinyl acetate polymer having a stable carbon isotope ratio of less than -20‰ is used as the vinyl acetate polymer, the carbon isotope ratio in the resulting vinyl alcohol polymer will be less than -20‰.

[0108] When the vinyl acetate polymer contains more than 0 ppm but not more than 100 ppm of sulfur, the resulting vinyl alcohol polymer contains more than 0 ppm but not more than 100 ppm of sulfur. As described above, the sulfur contained is preferably dimethyl sulfide or dimethyl sulfoxide, from the viewpoint of ease of tracing.

[0109] When the polymer having vinyl acetate as a monomer unit is a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, a vinyl alcohol polymer containing an ethylene unit obtained by saponifying a vinyl acetate-ethylene copolymer in which the other copolymerizable monomer is ethylene is preferred. When the vinyl alcohol polymer contains ethylene units, the content of the ethylene units is preferably 1 mol% or more and 60 mol% or less, more preferably 1 mol% or more and 55 mol% or less.

[0110] The saponification degree of the vinyl alcohol polymer is preferably 80 mol % or more, more preferably 85 mol % or more, and even more preferably 90 mol % or more. The saponification degree 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 into vinyl alcohol units by saponification and vinyl alcohol units.

[0111] The degree of saponification of the vinyl alcohol polymer can be measured in accordance with the description of JIS K 6726: 1994. Specifically, when the degree of saponification is 99.5 mol% or less, the viscosity-average degree of polymerization (P) of an ethylene-modified vinyl alcohol polymer saponified to a degree of saponification of 99.5 mol% or more was calculated by the following formula using the intrinsic viscosity [η] (liter / g) measured in water at 30°C. P = ([η] × 10 4 / 8.29) (1 / 0.62)

[0112] From the viewpoint of ensuring sufficient mechanical strength of the resulting film, the degree of polymerization of the vinyl alcohol polymer is preferably 200 or more, more preferably 300 or more, and even more preferably 500 or more. From the viewpoint of productivity and water solubility of the vinyl alcohol polymer, the degree of polymerization is preferably 5,000 or less, and more preferably 3,000 or less.

[0113] The vinyl alcohol polymer preferably contains 1,2-glycol bonds. The content of 1,2-glycol bonds is preferably 0.2 mol% or more, more preferably 0.3 mol% or more, even more preferably 0.4 mol% or more, and particularly preferably 0.5 mol% or more. The content of 1,2-glycol bonds is preferably 2 mol% or less, more preferably 1.5 mol% or less, even more preferably 1.3 mol% or less, and particularly preferably 1.0 mol% or less.

[0114] From the viewpoints of ease of tracing as well as the hue of the film to be obtained and the viscosity stability of the aqueous solution during film formation, the vinyl alcohol polymer of the present invention is preferably a vinyl alcohol polymer that contains 1 mol % to 15 mol % of ethylene units relative to all monomer units in the vinyl alcohol polymer, has a degree of saponification of 85 mol % to 99.9 mol %, has propylene units at its terminals, and has a content of the propyl group relative to all monomer units of 0.0005 mol % to 0.1 mol (hereinafter, this may be referred to as an ethylene-modified vinyl alcohol polymer).

[0115] The viscosity-average degree of polymerization of the ethylene-modified vinyl alcohol polymer is preferably from 200 to 3,000, more preferably from 400 to 2,800, and even more preferably from 450 to 2,500. The viscosity-average degree of polymerization is a value obtained by measurement in accordance with JIS K 6726:1994, as described above.

[0116] The degree of saponification of the ethylene-modified vinyl alcohol polymer is preferably 80 mol % or more and 99.9 mol % or less, and more preferably 90 mol % or more and 99.9 mol % or less.

[0117] The ethylene-modified vinyl alcohol polymer preferably has 0.0005 mol % to 0.10 mol % of propyl groups at one end, more preferably 0.001 mol % to 0.08 mol %, and even more preferably 0.005 mol % to 0.05 mol %.

[0118] A preferred method for introducing the propyl group is, for example, a method in which ethylene and vinyl acetate are reacted in the presence of a propyl group-containing initiator and a chain transfer agent in a polymerization step. By using a propyl group-containing initiator and a propyl group-containing chain transfer agent in combination in this way, an ethylene-modified vinyl alcohol polymer having a specific amount of propyl groups introduced at one end can be efficiently produced.

[0119] Examples of initiators having a propyl group include n-propyl peroxydicarbonate, 1,1'-propane-1-nitrile, etc. The amount of the initiator having a propyl group used is preferably 0.000125% by mass or more and 0.25% by mass or less, more preferably 0.0003% by mass or more and 0.2% by mass or less, and even more preferably 0.0005% by mass or more and 0.15% by mass or less, based on vinyl acetate, in order to obtain the above-mentioned propyl group content.

[0120] Examples of chain transfer agents having a propyl group include propanethiol, propyl aldehyde, etc. In order to obtain the above-mentioned propyl group content, the concentration of the chain transfer agent having a propyl group in the system is preferably 0.0001% by mass or more and 0.005% by mass or less, more preferably 0.0002% by mass or more and 0.004% by mass or less, and even more preferably 0.0003% by mass or more and 0.003% by mass or less, based on vinyl acetate.

[0121] The polymerization temperature is not particularly limited, but is preferably 0°C to 180°C, more preferably 20°C to 160°C, and even more preferably 30°C to 150°C. When polymerization is performed at a temperature below the boiling point of the solvent used in the polymerization step, either reduced-pressure boiling polymerization, in which polymerization is performed while boiling the solvent under reduced pressure, or atmospheric non-boiling polymerization, in which polymerization is performed under conditions where the solvent is not boiled under atmospheric pressure, can be selected. Furthermore, when polymerization is performed at a temperature above the boiling point of the solvent used in the polymerization step, either pressurized non-boiling polymerization, in which polymerization is performed under conditions where the solvent is not boiled under pressure, or pressurized boiling polymerization, in which polymerization is performed while boiling the solvent under pressure, can be selected.

[0122] The ethylene pressure in the polymerization reactor in the polymerization step is not particularly limited, but is preferably 0.01 MPa to 0.9 MPa, more preferably 0.05 MPa to 0.7 MPa, and even more preferably 0.1 MPa to 0.65 MPa.

[0123] The polymerization rate of vinyl acetate at the outlet of the polymerization reactor is not particularly limited, but is preferably 10% to 90%, more preferably 15% to 85%.

[0124] The alkoxy group content of the vinyl alcohol polymer obtained by polymerizing vinyl acetate of the present invention is preferably 0.0005 mol % to 1 mol %, more preferably 0.0007 mol % or more, and even more preferably 0.001 mol % or more, based on the number of moles of all structural units (all monomer units and units having alkoxy groups) constituting the vinyl alcohol polymer, from the viewpoint of ease of tracing. On the other hand, the content is preferably 0.5 mol % or less, and even more preferably 0.3 mol % or less.

[0125] The alkoxy group-containing vinyl alcohol polymer can be produced by saponifying a vinyl ester polymer obtained by copolymerizing the vinyl acetate and an alkoxy group-containing unsaturated monomer of the present invention. The alkoxy group-containing monomer is not particularly limited as long as it is an unsaturated monomer having an alkoxy group and copolymerizable with a vinyl ester, and examples thereof include alkyl vinyl ether, alkyl allyl ether, and N-alkoxyalkyl(meth)acrylamide, with N-alkoxyalkyl(meth)acrylamide being preferred. The alkoxy group-containing monomer can be used alone or in combination of two or more, with the former being preferred.

[0126] In the case of the vinyl alcohol polymer of the present invention obtained by polymerizing vinyl acetate and ethylene, the polymer terminal has the following structural formula (I):

[0127] [ka]

[0128] (wherein Y is a hydrogen atom or a methyl group). and the following structural formula (II):

[0129] [ka]

[0130] (wherein Z is a hydrogen atom or a methyl group). A vinyl alcohol polymer having a structure (II) represented by the following formula, in which the total amount of structures (I) and (II) relative to all monomer units is 0.001 mol % or more and 0.1 mol % or less, is preferred from the viewpoints of ease of tracing, excellent viscosity stability at the initial stage of melting of the vinyl alcohol polymer, stabilizing the melt molding process, and coloration resistance under high temperatures such as 80°C and alkaline conditions. The total content is more preferably 0.07 mol % or less, even more preferably 0.05 mol % or less, and particularly preferably 0.02 mol % or less. Meanwhile, the total content is more preferably 0.002 mol % or more.

[0131] In this specification, the term "monomer unit" in a vinyl alcohol polymer refers to a vinyl alcohol unit, a vinyl ester unit, an ethylene unit in the case of a copolymer with ethylene, and other monomer units copolymerized as necessary, and the term "total monomer units" refers to the total number of moles of each monomer unit. In this case, units containing the terminal structure represented by Structure (I) or Structure (II) are also included in the calculation of the monomer units.

[0132] Both Structure (I) and Structure (II) are derived from the polymerization initiator used in the polymerization process. Structure (I) contains a cyclic ester structure formed by the reaction of a nitrile group derived from the polymerization initiator with a hydroxyl group in the same molecule, while Structure (II) is the structure before such reaction occurs.

[0133] The polymerization initiator can be an azonitrile compound containing an alkoxy group, which can introduce the structure (I) to the polymerization terminal. Examples of azonitrile compounds containing an alkoxy group include 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azobis(4-ethoxy-2,4-dimethylvaleronitrile), with 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) being preferred. These azonitrile compounds containing an alkoxy group are less likely to undergo abnormal decomposition upon contact with metals and have a high decomposition rate at low temperatures. Therefore, the use of the azonitrile compound allows for safe, efficient, and economical copolymerization of ethylene and vinyl esters.

[0134] The vinyl alcohol polymer having the structures (I) and (II) at its polymer terminals preferably has an ethylene unit content of 1 mol % or more and 15 mol % or less, more preferably 1 mol % or more and 10 mol % or less, even more preferably 1 mol % or more and 8 mol % or less, and particularly preferably 1 mol % or more and 5 mol % or less, from the viewpoint of hydrophilicity of the vinyl alcohol polymer.

[0135] The vinyl alcohol polymer having the structures (I) and (II) at the polymer terminals preferably has a viscosity-average degree of polymerization of 200 or more and 3,000 or less, more preferably 400 or more and 2,800 or less, and even more preferably 450 or more and 2,500 or more, from the viewpoint of the water-resistant adhesive viscosity of an adhesive obtained from the vinyl alcohol polymer.

[0136] Furthermore, the vinyl alcohol polymer having the structures (I) and (II) at its polymer terminals preferably has a degree of saponification of 85 mol % or more and 99.9 mol % or less, more preferably 90 mol % or more and 99.9 mol % or less, from the viewpoints of solubility in water and the water-resistant adhesion of an adhesive obtained from the vinyl alcohol polymer.

[0137] In the vinyl alcohol polymer having the structures (I) and (II) at the polymer terminals, the molar ratio R[I / (I+II)] of structure (I) to the sum of structures (I) and (II) preferably satisfies the following formula (1): The molar ratio R[I / (I+II)] more preferably satisfies the following formula (1-1), even more preferably satisfies the following formula (1-2), and particularly preferably satisfies the following formula (1-3). The molar ratio R[I / (I+II)] can be adjusted by washing the vinyl alcohol polymer after saponification. On the other hand, the molar ratio R[I / (I+II))] is preferably 0.1 or more. This is because it is difficult to achieve a molar ratio of less than 0.1 in the industrial production of EVOH, which would increase production costs. R<0.92-Et / 100 (1) R<0.90-Et / 100 (1-1) R<0.88-Et / 100 (1-2) R<0.85-Et / 100 (1-3) [In the formulas (1) to (1-3), Et is the ethylene unit content (mol %).]

[0138] Furthermore, the molar ratio R[I / (I+II)] of Structure (I) to the total of Structure (I) and Structure (II) preferably satisfies the following formula (2), more preferably the following formula (2-1): 0.8 <R+Et / 100 (2) 0.9 <R+Et / 100 (2-1) [In formulas (2) and (2-1), Et is the same as defined above.]

[0139] In the above formulas (1) to (1-3), if the molar ratio R[I / (I+II)] does not satisfy the above formula, the water solubility of the ethylene-vinyl alcohol copolymer decreases, and when the ethylene-vinyl alcohol copolymer is used as an adhesive, the high-speed coatability of the resulting adhesive decreases.

[0140] In addition, in the formulas (2) and (2-1), a large value on the right side means that the proportion of nitrile groups derived from the polymerization initiator converted to the cyclic ester structure is high, and formula (2-1) means that this proportion is even higher. By satisfying formula (2), the viscosity stability of the vinyl alcohol polymer at the beginning of melting is improved, and the sudden increase in viscosity at the beginning of melting, 5 to 20 minutes after the start of melting, can be suppressed. By satisfying formula (2-1), such viscosity increase can be further suppressed.

[0141] In the case of the vinyl alcohol polymer of the present invention obtained by polymerizing vinyl acetate and ethylene, a vinyl alcohol polymer having a block character of the ethylene unit of 0.90 to 0.99 is preferred from the viewpoint of ease of tracing, as well as from the viewpoint of the viscosity stability of the resulting coating agent and the barrier properties of the resulting coated paper when the vinyl alcohol polymer is used in a coating agent.

[0142] The block character is a numerical value that represents the distribution of ethylene units and vinyl alcohol units generated by saponification of vinyl ester units, and takes a value between 0 and 2. 0 indicates that ethylene units or vinyl alcohol units are distributed completely in blocks, and as the value increases, the alternation increases, with 1 indicating that ethylene units and vinyl alcohol units are present completely randomly and 2 indicating that ethylene units and vinyl alcohol units are present completely alternately. The block character is 13 The following can be determined by C-NMR. First, an ethylene-vinyl alcohol copolymer is saponified to a degree of saponification of 99.9 mol% or more, then thoroughly washed with methanol and dried under reduced pressure at 90°C for 2 days. The obtained fully saponified ethylene-vinyl alcohol copolymer is dissolved in DMSO-d6, and the obtained sample is subjected to spectrometry using a 500 MHz 13Measurement is performed using a C-NMR (JEOL GX-500) at 80°C. From the obtained spectrum chart, the molar fraction of vinyl alcohol-ethylene two-unit chains (AE), the molar fraction of vinyl alcohol units (A), and the molar fraction of ethylene units (E) are assigned and calculated according to the method described in T. Moritani and H. Iwasaki, 11, 1251-1259, Macromolecules (1978), and the block character (η) of the ethylene units is calculated from the following formula. η = (AE) / {2×(A)×(E)}

[0143] The ethylene-vinyl ester copolymer having the block character is stirred in a polymerization vessel using a wide paddle impeller at a stirring power per unit volume, Pv, of 0.5 to 10 kW / m 3 The vinyl ester can be obtained by contacting a solution containing a vinyl ester with an ethylene-containing gas while stirring the solution so that the Froude number Fr is 0.05 to 0.2.

[0144] As described above, the vinyl acetate of the present invention is different from the vinyl acetate obtained from conventional ethylene and acetic acid derived from fossil raw materials, and is obtained by 14 It has a value of C / C. 14 C / C plus δ 13 Therefore, the vinyl acetate of the present invention, the vinyl acetate polymer having vinyl acetate as a monomer unit obtained by polymerizing it, and the vinyl alcohol polymer which is a saponified product thereof, have a specific range of C. 14 C / C, more preferably a specific range of δ 13 Since the vinyl acetate polymer of the present invention has the formula C, it can be distinguished from commercially available or known vinyl acetate, vinyl acetate polymers obtained by polymerizing vinyl acetate, and saponified products thereof. Therefore, the vinyl acetate polymers and vinyl alcohol polymers obtained using the vinyl acetate of the present invention can be traced even after production or sale.

[0145] The method for tracking vinyl acetate polymers and vinyl alcohol polymers after production involves first measuring the amount of vinyl acetate, which is the raw material before polymerization, used to produce vinyl acetate polymers and their saponified vinyl alcohol polymers. 14 If C / C is analyzed and recorded, the amount of vinyl acetate polymer or vinyl alcohol polymer recovered after manufacturing or sales can be 14 The C / C was measured and the results were compared with the raw material vinyl acetate, which was previously measured. 14 By comparing C / C, it is possible to determine whether the recovered vinyl acetate polymer or vinyl alcohol polymer is a company product, and if it is a company product, it is possible to identify the lot, etc. Furthermore, δ 13 By setting C within a certain range, these determinations become easier.

[0146] Furthermore, in addition to the above, the vinyl acetate of the present invention can be further traceable by containing at least one of the acetate ester, polymerization inhibitor, polyhydric alcohol, hydroxycarboxylic acid, hydroxylactone compound, and acetaldehyde dimethyl acetal in the above-mentioned ranges.

[0147] Furthermore, a vinyl alcohol polymer, which is a saponification product of a vinyl acetate polymer obtained by polymerizing the vinyl acetate of the present invention and containing the vinyl acetate of the present invention as a monomer unit, contains at least one of the 1,2-glycol bond, a propylene group or an alkoxy group at the polymer terminal, Structure (I) and Structure (II), and a block character within the above-mentioned ranges, thereby facilitating traceability and improving the properties of the resulting vinyl alcohol polymer, making it suitable for use in the intended application.

[0148] of products collected after use 14 C / C and δ 13In addition to measuring C, by measuring at least one of the 1,2-glycol bond, the propylene group or alkoxy group at the polymer terminal, the structure (I) and the structure (II), and the block character by the above-mentioned method, it is possible to determine whether or not the recovered product contains a vinyl alcohol polymer made by the company, and further to determine the production line, etc.

[0149] As described above, since raw materials can be traced from the vinyl acetate polymer having vinyl acetate as a monomer unit of the present invention and its saponified vinyl alcohol polymer, it is possible to feed back the quality of the vinyl acetate raw material from the quality of the molded product obtained from the vinyl acetate polymer or vinyl alcohol polymer. Furthermore, it becomes easy to investigate the production line of the vinyl acetate polymer or vinyl alcohol polymer and the vinyl acetate raw material from the molded product.

[0150] In the above description, examples of substances, conditions, methods, numerical ranges, etc. are given, but the present invention is not limited to such examples. Specifically, the present invention is not limited to each embodiment, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, unless otherwise noted, the exemplified substances may be used alone or in combination of two or more. [Example]

[0151] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples. In the following examples, measurements and evaluations were carried out according to the following methods.

[0152] (1) Analysis of vinyl acetate Gas chromatography was used to analyze 6 g of the reaction solution, to which 1 g of n-propyl acetate was added as an internal standard. The measurement conditions were as follows:

[0153] Equipment: Shimadzu Corporation GC-9A Detector: FID Column: GL Sciences TC-WAX (length 30 m, inner diameter 0.25 mm, film thickness 0.5 μm) Injection temperature: 200℃ Detector temperature: 200℃ Column temperature: 45°C (held for 2 minutes) heated to 130°C at a rate of 4°C / min and held for 15 minutes, then heated to 200°C at a rate of 25°C / min and held for 10 minutes.

[0154] (2) Carbon isotope ratio measurement The sample was converted to carbon dioxide using the pretreatment method (ASTM D6866 / Method B) specified by the American Society of Testing and Materials, and then graphitized by complete reduction using an iron catalyst. The carbon stable isotope ratio (δ 13 C) was calculated using the formula (3) above. Also, 14 The carbon isotope ratios of the samples and the standard ( 14 C / 12 C ratio, 13 C / 12 C ratio) and from the measurement results 14 The C concentration of the sample obtained by the measurement was calculated. 14 Using the carbon concentration, the mixture ratio of biomass-derived carbon and fossil-derived carbon in the sample was evaluated.

[0155] (3) Sulfur content measurement The sulfur content was determined using a Mitsubishi Analytech trace nitrogen and sulfur analyzer (TS-2100H type) under the following measurement conditions. Heater temperature: Inlet 900℃, Outlet 900℃ Gas flow rate: Ar, O2 each 300 ml / min [Analysis System NSX-2100] Measurement mode: TS Parameters: SD-210 Measurement time (timer): 540 seconds (9 minutes) PMT sensitivity: high concentration

[0156] (4) Sulfur components were identified using gas chromatography (GC) and gas chromatography mass spectrometry (GC / MS). The GC detector used was a flame photometric detector (FPD), which has high sensitivity to trace amounts of sulfur and phosphorus compounds. The sulfur components were identified by analyzing the mass components observed at the retention time when they were detected.

[0157] (5) Degree of saponification and average degree of polymerization of vinyl alcohol polymer After polymerization, unreacted vinyl acetate monomer was removed, and the resulting methanol solution of polyvinyl acetate was saponified with an alkali molar ratio of 0.5. The pulverized product was left at 60°C for 5 hours to allow saponification to proceed. This was followed by a methanol Soxhlet separation for 3 days, followed by drying under reduced pressure at 80°C for 3 days to obtain a purified vinyl alcohol polymer. The degree of saponification and average degree of polymerization of this purified vinyl alcohol polymer were measured in accordance with JIS K6726:1994.

[0158] (6) Ethylene unit content and degree of saponification of ethylene-vinyl alcohol copolymer Ethylene-vinyl alcohol copolymer pellets were dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard and tetrafluoroacetic acid as an additive, and the pellets were measured using a 500 MHz 1 The ethylene unit content and the degree of saponification were measured at 80°C using H-NMR (JMTC-400 / 54 / SS manufactured by JEOL Ltd.). The peaks in the spectrum obtained by the above measurement are assigned as follows: 0.6 to 1.9 ppm: methylene protons (4H) of ethylene units, methylene protons (2H) of vinyl alcohol units, methylene protons (2H) of vinyl acetate units 1.9 to 2.0 ppm: methyl protons (3H) of vinyl acetate units 3.1 to 4.2 ppm: methine proton (1H) of vinyl alcohol unit

[0159] (7) Determination of carboxylic acids 20 g of ethylene-vinyl alcohol copolymer pellets and 100 mL of ion-exchanged water were placed in a 200 mL Erlenmeyer flask with a stopper, a cooling condenser was attached, and the mixture was stirred and extracted at 95°C for 6 hours. The resulting extract was neutralized with a 50% N / 50 aqueous sodium hydroxide solution using phenolphthalein as an indicator, and the carboxylic acid content, calculated as a carboxylic acid radical, was quantified. When phosphorus compounds were present, the amount of carboxylic acid was calculated taking into account the content of phosphorus compounds measured using the evaluation method described below.

[0160] (8) Quantitative determination of metal ions, phosphate compounds, and boron compounds 0.5 g of ethylene-vinyl alcohol copolymer pellets were placed in a Teflon pressure vessel, and 5 mL of concentrated nitric acid was added and decomposed at room temperature for 30 minutes. After 30 minutes, the vessel was capped and heated in a wet decomposition apparatus (Actac "MWS-2") at 150°C for 10 minutes and then at 180°C for 5 minutes. The decomposition was then carried out, and the mixture was then cooled to room temperature. The cooled solution was transferred to a 50 mL volumetric flask (TPX) and made up to 100 mL with purified water. Elemental analysis of this solution was performed using an ICP emission spectrometer (PerkinElmer "OPTIMA4300DV") to determine the metal atom equivalent of metal ions, the phosphorus atom equivalent of phosphorus compounds, and the boron atom equivalent of boron compounds contained in the ethylene-vinyl alcohol copolymer pellets.

[0161] (9) Oxygen permeability A single-layer film with an average thickness of 20 μm was produced from ethylene-vinyl alcohol copolymer pellets using a single-screw extruder (Toyo Seiki Seisakusho Co., Ltd., "D2020"; D (mm) = 20, L / D = 20, compression ratio = 3.0, screw: full flight). The conditions are as follows. The resulting film was conditioned at 20°C / 65% RH, and then its oxygen permeability was measured at 20°C / 65% RH using an oxygen permeability measuring device (ModernControl, "OX-Tran2 / 20"). The measurement was performed in accordance with JIS K 7126-2 (constant pressure method; 2006) and ISO 14663-2 annex C. (Single screw extrusion equipment conditions) Extrusion temperature: 210℃ Screw rotation speed: 40 rpm Dice width: 30cm Take-up roll temperature: 80℃ Take-up roll speed: 3.1 m / min

[0162] (10) Appearance evaluation (10-1) Evaluation of defects in monolayer film Monolayer films were produced by continuous operation under the same conditions as above, and the number of defects per 17 cm of film length was counted for each film produced 5 hours after the start of operation. The defect count was performed using a film defect inspection device ("AI-10" manufactured by Frontier Systems Co., Ltd.). The detection camera in this film defect inspection device was installed so that its lens was 195 mm from the film surface.

[0163] (10-2) Evaluation of coloring of roll edge Five hours after the start of operation, 100 m of the film produced was wound around a paper tube to produce a roll, and the presence or absence of discoloration due to yellowing at the end of the roll was visually determined.

[0164] (11) 1,2-glycol bond content The vinyl alcohol polymer was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard substance and tetrafluoroacetic acid as an additive, and the1 Measurement was performed at 80°C using H-NMR (JEOL Ltd., "JMTC-400 / 54 / SS") The peak derived from the methine proton of the vinyl alcohol unit was assigned to 3.2 to 4.0 ppm (integral value A), and the peak derived from one methine proton of the 1,2-glycol bond was assigned to around 3.15 to 3.35 ppm (integral value B). The amount of 1,2-glycol bonds was calculated using the following formula: 1,2-glycol bond amount (mol%) = B / A × 100

[0165] (12) Propyl group content at one end The content of propyl groups at one end of the vinyl alcohol polymer is determined by the amount of the vinyl ester polymer, which is the precursor or reacetylated product of the vinyl alcohol polymer. 1 The ethylene-modified vinyl ester polymer sample was purified by reprecipitation using a mixed solution of n-hexane and acetone at least three times, and then dried under reduced pressure at 80°C for three days to prepare the ethylene-modified vinyl ester polymer for analysis. The ethylene-modified vinyl ester polymer for analysis was dissolved in DMSO-d6 and analyzed by a 500 MHz spectrophotometer. 1 Measurement was performed using H-NMR (JEOL Ltd., "JMTC-400 / 54 / SS") at 80°C. The propyl group content was calculated using the peak (integral value R: 4.7 to 5.2 ppm) derived from the main chain methine protons of vinyl acetate and the peak (integral value S: 0.7 to 1.0 ppm) derived from the methyl protons of the propyl group according to the following formula: Propyl group content (mol%) = 100 × (S / 3) / R

[0166] (13) Sodium acetate content of resin material The content of sodium acetate in a resin material containing a vinyl alcohol polymer as a main component is determined according to the dissolution conductivity method described in JIS K 6726:1994.

[0167] (14) Solubility of resin materials 10g of resin material is mixed with 90g of water, i.e., 100g of a 10% aqueous solution of the resin material, and stirred at 90°C and 300 rpm for 5 hours. The entire mixture is then filtered through a 200-mesh wire mesh. Note that 200 mesh corresponds to a mesh size of 75μm in terms of the JIS standard sieve. The mesh size of the sieve is determined in accordance with the nominal mesh size W of JIS Z 8801-1-2006. The mass of the wire mesh before filtration is defined as a (g). The wire mesh is then dried at 105°C for 3 hours. The total mass of the wire mesh and any material remaining on it after drying is defined as b (g). The solubility (%) of the resin material is calculated using the following formula: Solubility (%) = 100 - 100 × {(ba) / 10}

[0168] (15) Viscosity stability of aqueous solutions of resin materials 100g of a 10% aqueous solution of the resin material prepared under the above conditions was left at 5°C, and the viscosity c was determined when the liquid temperature reached 5°C. This was compared to the viscosity d after leaving it at 5°C for 48 hours, and the viscosity stability of the aqueous solution was determined from the ratio (viscosity ratio) d / c. A higher d / c value indicates a greater increase in viscosity when left at 5°C, and therefore poorer viscosity stability. The viscosity (mPa·s) was measured using a Brookfield viscometer (BLII, manufactured by Toki Sangyo Co., Ltd.) at a rotor speed of 60 rpm and a temperature of 20°C.

[0169] (16) Color of resin material (YI) The hue of the resin material was determined by the yellow index (YI) of the powder. After removing particles smaller than 100 μm and larger than 1,000 μm using sieves (mesh openings: 100 μm and 1,000 μm), the color was measured using a color meter (SM-T-H1, manufactured by Suga Test Instruments Co., Ltd.). The YI was measured and calculated in accordance with JIS Z 8722:2009 and JIS K 7373:2006.

[0170] (17) Content of Structures (I) and (II) The vinyl alcohol polymer was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetramethylsilane as an internal standard substance and tetrafluoroacetic acid as an additive, and the 1Measurements were performed at 45°C using H-NMR (JEOL Ltd., "JMTC-400 / 54 / SS"). The contents of structures (I) and (II) were determined from the peak intensity ratio of the ethylene unit, vinyl alcohol unit, and vinyl ester unit to the peak intensity ratio of the methyl hydrogen of the methoxy group or the methylene hydrogen of the ethoxy group in structures (I) and (II). The peaks of the methyl hydrogen of the methoxy group or the methylene hydrogen of the ethoxy group in structure (I) and the peaks of the methyl hydrogen of the methoxy group or the methylene hydrogen of the ethoxy group in structure (II) were detected at around 3.07 ppm and 3.09 ppm, respectively.

[0171] (18) Block character of ethylene units in ethylene-vinyl alcohol copolymer Ethylene-vinyl alcohol copolymer was dissolved in dimethyl sulfoxide (DMSO)-d6 containing tetrafluoroacetic acid as an additive, and the 13 Measurements were performed at 80°C using a C-NMR (JEOL Ltd., "JMTC-400 / 54 / SS") From the obtained spectrum chart, the molar fraction of vinyl alcohol-ethylene dimers (AE), the molar fraction of vinyl alcohol units (A), and the molar fraction of ethylene units (E) were assigned and calculated using the method described in T. Moritani and H. Iwasaki, Macromolecules (1978), Vol. 11, pp. 1251-1259. The block character (η) of the ethylene units was calculated using the following formula: η = (AE) / {2×(A)×(E)}

[0172] <Synthesis Example 1: Preparation of vinyl acetate synthesis catalyst> A silica sphere carrier is impregnated with an aqueous solution containing sodium tetrachloropalladate and tetrachloroauric acid tetrahydrate in an amount equivalent to the carrier's water absorption, and then immersed in an aqueous solution containing sodium metasilicate nonahydrate and allowed to stand. Subsequently, an aqueous solution of hydrazine hydrate is added, and the carrier is allowed to stand at room temperature. The carrier is then washed with water until chloride ions are no longer present in the water and dried. The resulting palladium / gold / carrier composition is then immersed in an aqueous solution of acetic acid and allowed to stand. The carrier is then washed with water and dried. The carrier is then impregnated with an aqueous solution of potassium acetate in an amount equivalent to the carrier's water absorption, and dried to obtain a vinyl acetate synthesis catalyst.

[0173] <Synthesis Example 2: Production of bioethylene from rice straw> Bioethanol is obtained from rice straw, a C3 plant, by processing it through an alkali treatment process, a saccharification process, and an ethanolization process. This bioethanol is then subjected to a dehydration reaction at 190°C using mordenite as a catalyst, yielding bioethylene derived from C3 plants.

[0174] <Synthesis Example 3: Production of bioacetic acid from rice straw> Bioacetic acid derived from C3 plants can be obtained by oxidizing the bioethanol obtained in Synthesis Example 2.

[0175] Example 1 The catalyst obtained in Synthesis Example 1 was diluted with glass beads and packed into a stainless steel reaction tube, and a mixed gas of ethylene, oxygen, water, acetic acid, and nitrogen was passed through to carry out the reaction. Bioethylene (manufactured by Braskem SA) derived from sugarcane, a C4 plant, was used as the ethylene. Acetic acid was obtained by vaporizing bioacetic acid derived from sugarcane, a C4 plant, and then introducing it into the reaction system as steam. The yield and selectivity of vinyl acetate were obtained by analyzing the reaction outlet gas. The vinyl acetate obtained was analyzed by the above method. 14 C / C and δ 13 The carbon dioxide and sulfur content were measured. The vinyl acetate obtained was designated VAM-1, and the results are shown in Table 1.

[0176] <Example 2> The reaction was carried out in the same manner as in Example 1, except that the total amount of bioacetic acid was changed to petroleum-derived acetic acid. The yield and selectivity of vinyl acetate were obtained by analyzing the reaction outlet gas. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon dioxide and sulfur content were measured. The vinyl acetate obtained was designated VAM-2, and the results are shown in Table 1.

[0177] Example 3 The reaction was carried out in the same manner as in Example 1, except that half of the bioethylene was replaced with petroleum-derived ethylene and all of the bioacetic acid was replaced with petroleum-derived acetic acid. The reaction outlet gas was analyzed to obtain the yield and selectivity of vinyl acetate. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon dioxide and sulfur content were measured. The vinyl acetate obtained was designated VAM-3, and the results are shown in Table 1.

[0178] Example 4 The reaction was carried out in the same manner as in Example 1, except that the total amount of bioethylene was changed to ethylene derived from C3 plants obtained in Synthesis Example 2, and the total amount of bioacetic acid was changed to acetic acid derived from C3 plants obtained in Synthesis Example 3. The reaction outlet gas was analyzed to obtain the yield and selectivity of vinyl acetate. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon dioxide and sulfur content were measured. The vinyl acetate obtained was designated VAM-4, and the results are shown in Table 1.

[0179] <Example 5> The reaction was carried out in the same manner as in Example 1, except that the total amount of bioethylene was changed to ethylene derived from C3 plants obtained in Synthesis Example 2, and the total amount of bioacetic acid was changed to acetic acid derived from petroleum. The reaction outlet gas was analyzed to obtain the yield and selectivity of vinyl acetate. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon and sulfur content of the resulting vinyl acetate was designated VAM-5, and the results are shown in Table 1.

[0180] Example 6 The reaction was carried out in the same manner as in Example 1, except that half of the bioethylene was replaced with ethylene derived from C3 plants obtained in Synthesis Example 2, the remaining half was replaced with petroleum-derived ethylene, and all of the bioacetic acid was replaced with petroleum-derived acetic acid. The reaction outlet gas was analyzed to obtain the yield and selectivity of vinyl acetate. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon and sulfur content of the resulting vinyl acetate was designated VAM-6, and the results are shown in Table 1.

[0181] <Comparative Example 1> The reaction was carried out in the same manner as in Example 1, except that the total amount of bioethylene was changed to petroleum-derived ethylene and the total amount of bioacetic acid was changed to petroleum-derived acetic acid. The yield and selectivity of vinyl acetate were obtained by analyzing the reaction outlet gas. The obtained vinyl acetate was analyzed by the above method. 14 C / C and δ 13 The carbon content and sulfur content of the resulting vinyl acetate were measured. The vinyl acetate was designated VAM-C1, and the results are shown in Table 1.

[0182] [Table 1] In Table 1, S is the sulfur content in vinyl acetate. The vinyl acetate obtained by the methods described in Examples 1 to 6 contained dimethyl sulfide and / or dimethyl sulfoxide as sulfur components.

[0183] <Reference example 1> To the vinyl acetate (VAM-1) obtained in Example 1, 3 ppm of hydroquinone was added as a polymerization inhibitor.

[0184] <Reference example 2> To the vinyl acetate (VAM-1) obtained in Example 1, 15 ppm of hydroquinone was added as a polymerization inhibitor.

[0185] Example 7 A reactor equipped with a stirrer, reflux condenser, nitrogen inlet, and polymerization initiator inlet was charged with 720 parts by mass of the vinyl acetate (VAM-1) obtained in Example 1 and 280 parts by mass of methanol. The system was then purged with nitrogen for 30 minutes while bubbling with nitrogen. The reactor was heated, and when the internal temperature reached 60°C, 0.13 parts by mass of 2,2'-azobisisobutyronitrile was added to initiate polymerization. Polymerization continued at 60°C for 3 hours, followed by cooling to terminate the polymerization. Subsequently, unreacted vinyl acetate was removed at 30°C under reduced pressure with occasional addition of methanol, yielding a methanol solution of vinyl acetate polymer. Next, methanol was added to this methanol solution to prepare a vinyl acetate polymer methanol solution. To this methanol solution, 9.2 parts by mass of a 10% by mass sodium hydroxide solution was added, and saponification was carried out at 40°C. After adding the sodium hydroxide methanol solution, a gel-like substance formed approximately 15 minutes later. This was crushed in a grinder and left at 40°C for an additional hour to allow saponification to proceed. Then, 500 parts of methyl acetate were added to neutralize the remaining alkali. After confirming completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. 2,000 parts of methanol was added to the white solid, which was then left to stand at room temperature for 3 hours for washing. This washing procedure was repeated three times, and the resulting white solid was centrifuged for dewatering. It was then heat-treated in a dryer at 120°C for 4.5 hours to obtain a vinyl alcohol polymer (PVOH-1). The physical properties of PVOH-1 are shown in Table 2.

[0186] Example 8 The reaction was carried out in the same manner as in Example 7, except that the total amount of vinyl acetate was changed to VAM-2, to obtain a vinyl alcohol polymer (PVOH-2). The physical properties of PVOH-2 are shown in Table 2.

[0187] Example 9 The reaction was carried out in the same manner as in Example 7, except that the total amount of vinyl acetate was changed to VAM-3, to obtain a vinyl alcohol polymer (PVOH-3). The physical properties of PVOH-3 are shown in Table 2.

[0188] Example 10 The reaction was carried out in the same manner as in Example 7, except that half of the vinyl acetate was replaced with VAM-1 and the other half with VAM-C1, to obtain a vinyl alcohol polymer (PVOH-4). The physical properties of PVOH-4 are shown in Table 2.

[0189] Example 11 The reaction was carried out in the same manner as in Example 7, except that the total amount of vinyl acetate was changed to VAM-4, to obtain a vinyl alcohol polymer (PVOH-5). The physical properties of PVOH-5 are shown in Table 2.

[0190] Example 12 The reaction was carried out in the same manner as in Example 7, except that the total amount of vinyl acetate was changed to VAM-5, to obtain a vinyl alcohol polymer (PVOH-6). The physical properties of PVOH-6 are shown in Table 2.

[0191] Example 13 The reaction was carried out in the same manner as in Example 7, except that the total amount of vinyl acetate was changed to VAM-6, to obtain a vinyl alcohol polymer (PVOH-7). The physical properties of PVOH-7 are shown in Table 2.

[0192] Example 14 The reaction was carried out in the same manner as in Example 7, except that half of the vinyl acetate was replaced with VAM-4 and the other half with VAM-C1, to obtain a vinyl alcohol polymer (PVOH-8). The physical properties of PVOH-8 are shown in Table 2.

[0193] <Comparative Example 2> A vinyl alcohol polymer (PVOH-C1) was obtained by carrying out the reaction in the same manner as in Example 4, except that the total amount of vinyl acetate was changed to VAM-C1. The physical properties of PVOH-C1 are shown in Table 1.

[0194] [Table 2]

[0195] As is clear from Table 2, different 14 C / C and δ 13Even if vinyl acetate having C is used, if it is polymerized and saponified under the same conditions, a vinyl alcohol polymer with the same physical properties will be obtained.

[0196] Example 15 (Production of ethylene-vinyl acetate copolymer) A 250 L pressurized reactor equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet, and an initiator addition port was charged with 105 kg of VAM-1 and 32.3 kg of methanol. The temperature was raised to 65°C, and nitrogen bubbling was performed for 30 minutes to replace the atmosphere inside the reactor. Ethylene was then introduced at elevated pressure until the reactor pressure (ethylene pressure) reached 3.67 MPa. Sugarcane-derived ethylene (manufactured by Braskem SA) was used. After adjusting the temperature inside the reactor to 65°C, 16.8 g of 2,2'-azobis(2,4-dimethylvaleronitrile) was added as a methanol solution as an initiator to initiate polymerization. The ethylene pressure was maintained at 3.67 MPa, and the polymerization temperature was maintained at 65°C during the polymerization. After 3 hours, when the conversion of vinyl acetate reached 45%, the polymerization was terminated by cooling. The reactor was opened to remove ethylene, and nitrogen gas was bubbled through to completely remove the ethylene. Next, unreacted vinyl acetate was removed under reduced pressure, and then methanol was added to the resulting ethylene-vinyl acetate copolymer to prepare a 20% by mass methanol solution.

[0197] (Saponification and cleaning) 250 kg of the resulting 20% ​​by weight methanol solution of the ethylene-vinyl acetate copolymer jacket was placed in a 500 L reactor equipped with a stirrer, nitrogen inlet, reflux condenser, and solution addition port. The solution was heated to 60°C while nitrogen was blown into it, and 4 kg of sodium hydroxide was added as a 2N methanol solution. After the sodium hydroxide addition was completed, the system was stirred for 2 hours while maintaining the temperature at 60°C to allow the saponification reaction to proceed. After 2 hours, 4 kg of sodium hydroxide was added again in the same manner, and heating and stirring were continued for 2 hours. Subsequently, 14 kg of acetic acid was added to terminate the saponification reaction, and 50 kg of ion-exchanged water was added. Methanol and water were distilled out of the reactor while heating and stirring, concentrating the reaction solution. After 3 hours, an additional 50 kg of ion-exchanged water was added to precipitate the ethylene-vinyl alcohol copolymer. The precipitated ethylene-vinyl alcohol copolymer was collected by decantation and pulverized in a mixer. The obtained ethylene-vinyl alcohol copolymer (EVOH-1) powder was placed in an aqueous acetic acid solution (bath ratio 20) of 1 g of acetic acid to 1 L of water (1 g / L) (1 g / L, 200 L of ion-exchanged water to 10 kg of powder) and washed with stirring for 2 hours. The powder was deliquored and then placed in a 1 g / L aqueous acetic acid solution (bath ratio 20) and washed with stirring for 2 hours. The deliquored powder was placed in ion-exchanged water (bath ratio 20), washed with stirring for 2 hours, and then deliquored. This process was repeated three times for purification. The powder was dried at 60°C for 16 hours to obtain a crude dried EVOH-1 product.

[0198] (Production of wet pellets) 25 kg of the resulting crude dried EVOH-1 was placed in a 100 L stirring tank equipped with a jacket, stirrer, and reflux condenser. 20 kg of water and 20 g of methanol were added and the mixture was heated to 70 °C to dissolve the material. The resulting solution was extruded through a 3 mm diameter glass tube into a 90 / 10 water / methanol mixture cooled to 5 °C, resulting in strands. These strands were then cut into pellets with a strand cutter to obtain hydrous EVOH-1 pellets. The hydrous EVOH-1 pellets were then placed in a 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred for 2 hours. The pellets were then drained and placed in a 1 g / L aqueous acetic acid solution (bath ratio 20) and stirred for 2 hours. After draining, the aqueous acetic acid solution was renewed and the same procedure was repeated. After washing with an aqueous acetic acid solution and then draining, the material was poured into ion-exchanged water (bath ratio 20), stirred and washed for two hours, and drained. This process was repeated three times for purification, yielding hydrous pellets of EVOH-1 from which the catalyst residue from the saponification reaction and the methanol used in strand precipitation had been removed. The moisture content of the obtained hydrous pellets of EVOH-1 was measured using a Mettler halogen moisture meter, HR73.

[0199] (Pellet production) The resulting EVOH-1 hydrous pellets were placed in an aqueous solution (bath ratio 20) containing sodium acetate, acetic acid, concentrated phosphoric acid, and boric acid, and immersed for 4 hours with periodic stirring. The concentration of each component was adjusted so that the content of each component in the resulting EVOH-1 pellets was as shown in Table 3. After immersion, the pellets were drained and dried in air at 80°C for 3 hours and then at 130°C for 7.5 hours to obtain EVOH-1 pellets containing sodium acetate, acetic acid, phosphoric acid, and boric acid. The physical properties are shown in Table 3.

[0200] Example 16 The reaction was carried out in the same manner as in Example 15, except that the total amount of vinyl acetate was changed to VAM-2, to obtain ethylene-vinyl alcohol copolymer (EVOH-2) pellets. The physical properties are shown in Table 3.

[0201] Example 17 The reaction was carried out in the same manner as in Example 15, except that the total amount of vinyl acetate was changed to VAM-3, to obtain ethylene-vinyl alcohol copolymer (EVOH-3) pellets. The physical properties are shown in Table 3.

[0202] Example 18 The reaction was carried out in the same manner as in Example 15, except that half of the vinyl acetate was replaced with VAM-1 and the other half with VAM-C1, to obtain ethylene-vinyl alcohol copolymer (EVOH-4) pellets. The physical properties are shown in Table 3.

[0203] Example 19 The reaction was carried out in the same manner as in Example 15, except that the total amount of ethylene was changed to petroleum-derived ethylene, to obtain ethylene-vinyl alcohol copolymer (EVOH-5) pellets. The physical properties are shown in Table 3.

[0204] Example 20 The reaction was carried out in the same manner as in Example 15, except that half of the ethylene was replaced with petroleum-derived ethylene, to obtain ethylene-vinyl alcohol copolymer (EVOH-6) pellets. The physical properties are shown in Table 3.

[0205] Example 21 The reaction was carried out in the same manner as in Example 15, except that all of the ethylene was replaced with rice straw-derived ethylene and all of the vinyl acetate was replaced with VAM-4, to obtain ethylene-vinyl alcohol copolymer (EVOH-7) pellets. The physical properties are shown in Table 3.

[0206] <Example 22> The reaction was carried out in the same manner as in Example 15, except that all ethylene was replaced with rice straw-derived ethylene and all vinyl acetate was replaced with VAM-5, to obtain ethylene-vinyl alcohol copolymer (EVOH-8) pellets. The physical properties are shown in Table 3.

[0207] Example 23 The reaction was carried out in the same manner as in Example 15, except that all of the ethylene was replaced with rice straw-derived ethylene and all of the vinyl acetate was replaced with VAM-6, to obtain ethylene-vinyl alcohol copolymer (EVOH-9) pellets. The physical properties are shown in Table 3.

[0208] Example 24 The reaction was carried out in the same manner as in Example 15, except that all of the ethylene was replaced with rice straw-derived ethylene, half of the vinyl acetate was replaced with VAM-6, and the remaining half with VAM-C1, to obtain ethylene-vinyl alcohol copolymer (EVOH-10) pellets. The physical properties are shown in Table 3.

[0209] Example 25 The reaction was carried out in the same manner as in Example 15, except that all of the ethylene was replaced with petroleum-derived ethylene and all of the vinyl acetate was replaced with VAM-4, to obtain ethylene-vinyl alcohol copolymer (EVOH-11) pellets. The physical properties are shown in Table 3.

[0210] Example 26 The reaction was carried out in the same manner as in Example 15, except that half of the ethylene was replaced with rice straw-derived ethylene, the other half with petroleum-derived ethylene, and all of the vinyl acetate was replaced with VAM-4, to obtain ethylene-vinyl alcohol copolymer (EVOH-12) pellets. The physical properties are shown in Table 3.

[0211] <Comparative Example 3> The reaction was carried out in the same manner as in Example 8, except that all of the vinyl acetate was replaced with VAM-C1 and all of the ethylene was replaced with petroleum-derived ethylene, to obtain ethylene-vinyl alcohol copolymer (EVOH-C1) pellets. The physical properties are shown in Table 3.

[0212] [Table 3]

[0213] The obtained EVOH-1 to EVOH-6 and EVOH-C1 14 C / C and δ 13The C was measured by the above method. 14 C / C and δ 13 The values ​​are almost the same as those of C. 14 C / C and δ 13 Unlike EVOH-C1, which is made entirely from petroleum-derived vinyl acetate, EVOH-C is an ethylene-vinyl alcohol copolymer. 14 C / C and δ 13 By measuring C, it is possible to identify the raw material, and therefore it is possible to trace the ethylene-vinyl acetate alcohol copolymer.

[0214] As shown in Table 3, each of the EVOH compositions of Examples 15 to 26, although using some plant-derived raw materials, has high oxygen barrier properties comparable to those derived solely from fossil resources (EVOH composition of Comparative Example 3).

[0215] Example 27 The reaction was carried out in the same manner as in Example 15, except that 500 ppm of methyl acetate was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-13) pellets. When the physical properties of EVOH-1 and EVOH-13 were compared, it was found that EVOH-13 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-13 in C and oxygen permeability.

[0216] Example 28 The reaction was carried out in the same manner as in Example 15, except that 350 ppm of ethyl acetate was added to the vinyl acetate and the polymerization solvent was changed from methanol to ethanol, to obtain ethylene-vinyl alcohol copolymer (EVOH-14) pellets. A comparison of the physical properties of EVOH-1 and EVOH-14 revealed that EVOH-14 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-14 in C and oxygen permeability.

[0217] Example 29 The reaction was carried out in the same manner as in Example 21, except that 500 ppm of methyl acetate was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-15) pellets. A comparison of the physical properties of EVOH-1 and EVOH-15 revealed that EVOH-15 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-15 in C and oxygen permeability.

[0218] Example 30 The reaction was carried out in the same manner as in Example 21, except that 350 ppm of ethyl acetate was added to the vinyl acetate and the polymerization solvent was changed from methanol to ethanol, to obtain ethylene-vinyl alcohol copolymer (EVOH-16) pellets. A comparison of the physical properties of EVOH-7 and EVOH-16 revealed that EVOH-16 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-7 and EVOH-16 in C and oxygen permeability.

[0219] Example 31 The reaction was carried out in the same manner as in Example 15, except that 50 ppm of L-ascorbic acid was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-17) pellets. A comparison of the physical properties of EVOH-1 and EVOH-17 revealed that EVOH-17 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-17 in C and oxygen permeability.

[0220] Example 32 The reaction was carried out in the same manner as in Example 15, except that 50 ppm of erythorbic acid was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-18) pellets. A comparison of the physical properties of EVOH-1 and EVOH-18 revealed that EVOH-18 had improved film formation defects and roll edge coloration. 14C / C, δ 13 No difference was observed between EVOH-1 and EVOH-17 in C and oxygen permeability.

[0221] Example 33 The reaction was carried out in the same manner as in Example 15, except that 50 ppm of glucono-delta-lactone was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-19) pellets. When the physical properties of EVOH-1 and EVOH-19 were compared, it was found that EVOH-19 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-19 in C and oxygen permeability.

[0222] Example 34 The reaction was carried out in the same manner as in Example 21, except that 50 ppm of L-ascorbic acid was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-20) pellets. A comparison of the physical properties of EVOH-7 and EVOH-20 revealed that EVOH-20 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-7 and EVOH-20 in C and oxygen permeability.

[0223] Example 35 The reaction was carried out in the same manner as in Example 21, except that 50 ppm of erythorbic acid was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-21) pellets. A comparison of the physical properties of EVOH-7 and EVOH-21 revealed that EVOH-21 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-7 and EVOH-21 in C and oxygen permeability.

[0224] Example 36 The reaction was carried out in the same manner as in Example 21, except that 50 ppm of glucono-delta-lactone was added to the vinyl acetate, to obtain ethylene-vinyl alcohol copolymer (EVOH-22) pellets. When the physical properties of EVOH-7 and EVOH-22 were compared, it was found that EVOH-22 had improved film formation defects and roll edge coloration. 14 C / C, δ 13 No difference was observed between EVOH-1 and EVOH-22 in C and oxygen permeability.

[0225] As can be seen from Examples 15, 21, and 31 to 36, when the vinyl acetate of the present invention is polymerized alone or with other monomers, particularly when vinyl acetate is copolymerized with ethylene, in the co-presence of a polycarboxylic acid, a hydroxycarboxylic acid, a hydroxylactone compound, and a polymerization initiator, the resulting ethylene-vinyl acetate copolymer is useful as a raw material for a saponified ethylene-vinyl acetate copolymer, and the saponified ethylene-vinyl acetate copolymer obtained by saponifying such a copolymer can suppress fisheyes during film formation and has excellent hue.

[0226] Example 37 A reaction was carried out in the same manner as in Example 7, except that 0.5 parts by mass of acetaldehyde dimethyl acetal was added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-9). Visual inspection of PVOH-1 and PVOH-9 revealed that PVOH-9 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-1 and PVOH-9.

[0227] Example 38 A reaction was carried out in the same manner as in Example 7, except that 4 parts by mass of acetaldehyde dimethyl acetal was added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-10). Visual inspection of PVOH-1 and PVOH-10 revealed that PVOH-10 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-1 and PVOH-10.

[0228] Example 39 A reaction was carried out in the same manner as in Example 7, except that 4 parts by mass of acetaldehyde dimethyl acetal and 5 ppm of citric acid were added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-11). Visual inspection of PVOH-1 and PVOH-11 revealed that PVOH-11 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-1 and PVOH-11.

[0229] <Example 40> A reaction was carried out in the same manner as in Example 7, except that 4 parts by mass of acetaldehyde dimethyl acetal and 10 ppm of citric acid were added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-12). Visual inspection of PVOH-1 and PVOH-12 revealed that PVOH-12 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed between PVOH-1 and PVOH-12 for C.

[0230] <Example 41> A reaction was carried out in the same manner as in Example 11, except that 0.5 parts by mass of acetaldehyde dimethyl acetal was added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-13). Visual inspection of PVOH-5 and PVOH-13 revealed that PVOH-13 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-5 and PVOH-13.

[0231] <Example 42> A reaction was carried out in the same manner as in Example 11, except that 4 parts by mass of acetaldehyde dimethyl acetal was added to vinyl acetate, to obtain a vinyl alcohol polymer (PVOH-14). Visual inspection of PVOH-5 and PVOH-14 revealed that PVOH-14 was whiter and had a better hue. 14C / C and δ 13 No difference was observed in C between PVOH-5 and PVOH-14.

[0232] <Example 43> A vinyl alcohol polymer (PVOH-15) was obtained by carrying out the reaction in the same manner as in Example 11, except that 4 parts by mass of acetaldehyde dimethyl acetal and 5 ppm of citric acid were added to the vinyl acetate. Visual inspection of PVOH-5 and PVOH-15 revealed that PVOH-13 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-5 and PVOH-15.

[0233] <Example 44> A reaction was carried out in the same manner as in Example 11, except that 4 parts by mass of acetaldehyde dimethyl acetal and 10 ppm of citric acid were added to vinyl acetate, to obtain a vinyl alcohol polymer (EVOH-15). Visual inspection of PVOH-5 and PVOH-15 revealed that PVOH-13 was whiter and had a better hue. 14 C / C and δ 13 No difference was observed in C between PVOH-5 and PVOH-15.

[0234] As can be seen from Examples 7, 14, and 37 to 44, vinyl acetate polymers of good quality can be obtained by using vinyl acetate to which acetaldehyde dimethyl acetal has been added, and such polymers are also useful as raw materials for obtaining vinyl alcohol polymers with excellent hue.

[0235] Example 45 A continuous polymerization reactor equipped with a reflux condenser, raw material supply lines, reaction solution discharge lines, a thermometer, a nitrogen inlet, an ethylene inlet, and a stirring blade was used. VAM-1 was continuously fed into the continuous polymerization reactor at 671 L / hr, methanol at 148 L / hr, and a 1% methanol solution of n-propyl peroxydicarbonate (as an initiator) at 1.0 L / hr using metering pumps. The amount of n-propyl peroxydicarbonate added was 0.00132 mass% relative to VAM-1. The ethylene pressure in the continuous polymerization reactor was adjusted to 0.23 MPa. Sugarcane-derived ethylene (manufactured by Braskem SA) was used as the ethylene. The polymerization solution was continuously withdrawn from the continuous polymerization reactor to maintain a constant liquid level. The polymerization conversion at the reactor outlet was adjusted to 26%. During this process, propanethiol was continuously added as a chain transfer agent to a system concentration of 0.00042% by mass relative to VAM-1 (the concentration relative to the residual vinyl acetate in the continuously withdrawn polymerization solution, taken as 100). The residence time in the continuous polymerization vessel was 5 hours. The temperature at the outlet of the continuous polymerization vessel was 60°C. The polymerization solution was recovered from the continuous polymerization vessel and heated to 75°C in a hot water bath while introducing methanol vapor into the polymerization solution to remove the residual vinyl acetate, yielding a methanol solution of ethylene-modified vinyl ester polymer (hereinafter sometimes referred to as EVAc) (EVAc concentration: 32%). The average residence time in the removal step was 2 hours, and the residual vinyl acetate content in the resulting methanol solution of ethylene-modified vinyl ester polymer was 0.1%.

[0236] Next, the saponification reaction was carried out at 40°C for 1 hour using sodium hydroxide as a saponification catalyst at a molar ratio of 0.012 relative to the ethylene-modified vinyl ester polymer, with a water content of 0.5%. The resulting polymer was immersed in methanol and washed. The solvent was then removed by centrifugation, and the polymer was dried to obtain a composition containing an ethylene-vinyl alcohol copolymer (EVOH-23) as the main component, with a calculated ethylene unit content of 2 mol%, a viscosity-average polymerization degree of 1,700, a saponification degree of 98.5 mol%, a 1,2-glycol bond content of 1.6 mol%, and a propyl group content at one end of 0.0061 mol%, and a sodium acetate content of 0.42 mass%.

[0237] The resulting composition was used to measure the solubility of EVOH-23, viscosity stability of the aqueous solution, and hue when heated at 90°C for 5 hours. The solubility, viscosity stability of the aqueous solution, and hue (YI) were good.

[0238] <Example 46> A schematic diagram of the polymerization apparatus used is shown in Figure 1, and a schematic diagram of the impeller is shown in Figure 2. A roughly cylindrical polymerization vessel 1 (volume: 7,000 L, vessel inner diameter D: 1.8 m) equipped with a Max Blend impeller (manufactured by Kobelco Eco-Solutions Co., Ltd., impeller diameter (d): 1.1 m, impeller (paddle) width (b): 1.5 m) as impeller 8 was introduced into the vessel 1. Ethylene was introduced through conduit 5 to maintain the vessel ethylene pressure at 0.23 MPa, and a 1% by mass solution of 2,2'-azobis-(4-methoxy-2,4-dimethylvaleronitrile) in methanol was introduced through conduit 6 at a rate of 3 L / hr. Sugarcane-derived ethylene (manufactured by Braskem SA) was used as the ethylene. A VAM-1-containing solution (VAM-1: 777 L / hr, methanol: 170 L / hr) was introduced into the polymerization vessel 1 via inlet pipe 10 and heat exchanger 2. Ethylene-containing gas was introduced from the polymerization vessel 1 into the heat exchanger 2 via conduit 3. The VAM-1-containing liquid absorbed ethylene as it flowed down along the surface of the tube, and was then poured into the polymerization vessel 1 via conduit 4, mixed with the reaction liquid, and subjected to continuous polymerization with ethylene. The polymerization liquid was continuously withdrawn from conduit 9 so that the liquid level in the polymerization vessel 1 remained constant. The conversion of VAM-1 at the outlet of the polymerization vessel 1 was adjusted to 30%. The stirring power per unit volume, Pv, was 2.2 kW / m 3 The Froude number Fr was adjusted to 0.13. The reaction solution was stirred with the paddles fully immersed in the reaction solution and with the liquid surface close to the top of the paddles. The residence time of the reaction solution in the polymerization tank was 5 hours. The temperature at the outlet of the polymerization tank was 60°C. Methanol vapor was introduced into the continuously withdrawn polymerization solution to remove unreacted vinyl acetate monomer, yielding a methanol solution of ethylene-vinyl acetate copolymer (concentration 32% by mass).

[0239] Next, a methanol solution of sodium hydroxide (4% by mass) was added to a methanol solution of the ethylene-vinyl acetate copolymer (32% by mass) obtained in the polymerization step so that the molar ratio of sodium hydroxide to vinyl acetate units in the ethylene-vinyl acetate copolymer was 0.012. Furthermore, a methanol solution of sorbic acid (10% by mass) was added in an amount of 0.00018 parts by mass per 100 parts by mass of the ethylene-vinyl acetate copolymer. The resulting mixture was mixed in a static mixer, placed on a belt, and held at 40°C for 18 minutes to allow the saponification reaction to proceed. The mixture was then pulverized and dried to obtain an ethylene-vinyl alcohol copolymer (EVOH-24). Analysis revealed the following: ethylene unit content 2 mol%, viscosity-average degree of polymerization 1,700, degree of saponification 98.5 mol%, content of structure (I) 0.00114 mol%, content of structure (II) 0.0002 mol%, and block character of the ethylene units 0.95.

[0240] Example 47 A 250 L pressurized reactor equipped with a jacket, agitator, nitrogen inlet, ethylene inlet, and initiator addition port was charged with 83.0 kg of VAM-1 and 26.6 kg of methanol. The reactor was heated to 60 °C and then nitrogen was bubbled through for 30 minutes to purge the reactor. Ethylene was then introduced at elevated pressure until the reactor pressure (ethylene pressure) reached 3.6 MPa. Sugarcane-derived ethylene (Braskem SA) was used. After adjusting the reactor temperature to 60 °C, a 2.5 g / L methanol solution of 2,2'-azobis(2,4-dimethylvaleronitrile) was introduced as an initiator at an initial feed rate of 362 mL and a continuous feed rate of 1,120 mL / hr. The ethylene pressure was maintained at 3.6 MPa and the polymerization temperature at 60 °C during polymerization. When the conversion of vinyl acetate reached approximately 40%, sorbic acid was added and the system was cooled to terminate the polymerization. The reaction vessel was opened to remove ethylene, and then nitrogen gas was bubbled through to completely remove ethylene. Next, unreacted vinyl acetate was removed under reduced pressure, and methanol was added to the resulting ethylene-vinyl acetate copolymer to prepare a 20% by mass methanol solution.

[0241] The resulting methanol solution of ethylene-vinyl acetate copolymer was placed in a saponification reactor, and a 2 mol / L methanol solution of sodium hydroxide was added to the reactor in an amount equivalent to 3 moles per 1000 ppm of vinyl ester content. Methanol was then added to adjust the copolymer concentration to 5%. The solution was heated to 60°C and saponified for 3 hours with stirring. The final hour of the reaction was performed using a US Cleaner USK-2R ultrasonic cleaner, with ultrasonic waves irradiating the reactor at 80 W and 40 kHz. Acetic acid and water were then added to terminate the saponification reaction and precipitate the ethylene-vinyl alcohol copolymer. The precipitated ethylene-vinyl alcohol copolymer was recovered and crushed to obtain hydrous chips. The chips were then washed with an aqueous acetic acid solution and ion-exchanged water, and then immersed in an aqueous solution containing sodium acetate and acetic acid. The aqueous solution and the hydrous chips were separated and dehydrated, then placed in a hot air dryer and dried at 80°C for 3 hours, then at 110°C for 35 hours, to obtain ethylene-vinyl alcohol copolymer (EVOH-25) as dried chips. Analysis revealed that the degree of saponification was 99.9 mol% or more, the content of structure (I) was 0.0071 mol%, the content of structure (II) was 0.0027 mol%, and the contents of sodium and acetic acid were 180 ppm and 300 ppm, respectively.

[0242] Example 48 Tracking is done in the following ways: A barrier layer containing an ethylene-vinyl alcohol copolymer is removed from 10 samples of commercially available packaging containers. For this sample, 14 C / C and δ 13 C is calculated by the above method. The obtained value and the value recorded in advance at the time of manufacture are compared. 14 C / C and δ 13 By comparing the value with C, it is determined whether the product is from the company or not.

[0243] Example 49 Using EVOH-1 to EVOH-6 obtained in Examples 8 to 13, films 1 to 6 were obtained by the above method. The obtained films 1 to 6 were collected as packaging bags 1 to 6, respectively.14 C / C and δ 13 The value of C was measured by the above method and was consistent with the values ​​obtained in Examples 8 to 13. [Industrial Applicability]

[0244] The vinyl acetate of the present invention is different from conventional vinyl acetate in that: 14 Therefore, the vinyl acetate polymer containing vinyl acetate as a monomer unit obtained by polymerizing vinyl acetate of the present invention and the vinyl alcohol polymer which is its saponification product are also different from conventional products. 14 By utilizing this difference, it is possible to determine whether vinyl acetate polymers or vinyl alcohol polymers collected from the market are made using the vinyl acetate of the present invention, enabling tracking of one's own products. [Explanation of symbols]

[0245] 1 Polymerization tank 2 Heat exchanger 3 to 7 conduits 8. Mixer 9. Reaction liquid outlet pipe 10 Vinyl ester inlet pipe 11, 12 Refrigerant pipe 13 Gas exhaust pipe 21 Max Blend Wings

Claims

1. The ratio of carbon-14 to total carbon is 1.0 x 10 －１４ That's all vinyl acetate.

2. 2. The vinyl acetate according to claim 1, having a stable carbon isotope ratio of −20‰ or more.

3. 2. The vinyl acetate according to claim 1, having a stable carbon isotope ratio of less than −20‰.

4. 4. The vinyl acetate according to claim 1, having a sulfur content of more than 0 ppm and not more than 100 ppm.

5. 5. The vinyl acetate of claim 4, wherein the sulfur component is dimethyl sulfide or dimethyl sulfoxide.

6. 6. The vinyl acetate of claim 1, comprising 10 ppm to 1,500 ppm of acetate ester.

7. 7. The vinyl acetate of claim 6, wherein the acetate ester is at least one of methyl acetate and ethyl acetate.

8. The vinyl acetate according to any one of claims 1 to 7, containing more than 0 ppm to 100 ppm of a polymerization inhibitor.

9. The vinyl acetate according to any one of claims 1 to 8, comprising 1 ppm to 500 ppm of at least one compound selected from the group consisting of polycarboxylic acids, hydroxycarboxylic acids, and hydroxylactone compounds.

10. 10. The vinyl acetate according to any one of claims 1 to 9, comprising 0.001 to 10 parts by weight of acetaldehyde dimethyl acetal.

11. A vinyl acetate polymer containing the vinyl acetate according to any one of claims 1 to 10 as a monomer unit.

12. A vinyl alcohol polymer obtained by saponifying the vinyl acetate polymer according to claim 11.

13. The vinyl alcohol polymer according to claim 12, further comprising an ethylene unit, the content of which is from 1 mol % to 60 mol %.

14. The vinyl alcohol polymer according to claim 12 or 13, having a degree of saponification of 80 mol % or more.

15. The vinyl alcohol polymer according to any one of claims 12 to 14, having a viscosity average degree of polymerization of 200 or more and 5,000 or less.

16. The vinyl alcohol polymer according to any one of claims 12 to 15, wherein the content of 1,2-glycol bonds is 0.2 mol% or more and 2 mol% or less.

17. The ratio of carbon-14 to total carbon is 1.0 x 10 －１４ The vinyl alcohol polymer according to any one of claims 12 to 16, wherein

18. The vinyl alcohol polymer according to any one of claims 12 to 17, having a stable carbon isotope ratio of -20‰ or more.

19. The vinyl alcohol polymer according to any one of claims 12 to 17, having a stable carbon isotope ratio of less than -20‰.

20. The vinyl alcohol polymer according to any one of claims 12 to 19, having a sulfur content of more than 0 ppm and not more than 100 ppm.

21. 21. The vinyl alcohol polymer of claim 20, wherein the sulfur component is dimethyl sulfide or dimethyl sulfoxide.

22. The ethylene unit content is 1 mol% or more and 15 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The vinyl alcohol polymer according to any one of claims 12 to 21, which has propyl groups at polymer terminals, and the content of the propyl groups relative to all monomer units is 0.0005 mol% or more and 0.1 mol% or less.

23. The vinyl alcohol polymer according to any one of claims 12 to 22, which has alkoxy groups at polymer terminals, and the content of the alkoxy groups relative to all monomer units is 0.0005 mol% or more and 1 mol% or less.

24. 24. The vinyl alcohol polymer according to claim 12, having the following Structure (I) and Structure (II) at the polymer terminals, wherein the total content of Structure (I) and Structure (II) relative to all monomer units constituting the vinyl alcohol polymer is 0.001 mol % or more and 0.1 mol % or less. 【Chemistry 1】 (wherein Y is a hydrogen atom or a methyl group). 【Chemistry 2】 (wherein Z is a hydrogen atom or a methyl group).

25. The ethylene unit content is 1 mol% or more and 15 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The molar ratio R [I / (I+II)] of the structure (I) to the sum of the structure (I) and the structure (II) is expressed by the following formula (1): R<0.92-Et / 100 (1) The vinyl alcohol polymer according to claim 24, which satisfies the following formula: (In formula (1), Et is the ethylene unit content (mol %).)

26. 26. The vinyl alcohol polymer of any one of claims 13, 22 or 25, wherein the block character of the ethylene units is from 0.90 to 0.

99.

27. The ethylene unit content is 15 mol% or more and 60 mol% or less, and the saponification degree is 85 mol% or more and 99.9 mol% or less, The total content of the structure (I) and the structure (II) is 0.002 mol % or more and 0.02 mol % or less with respect to all monomer units constituting the vinyl alcohol polymer, and the molar ratio R [I / (I+II)] of the structure (I) to the total of the structure (I) and the structure (II) is expressed using the ethylene unit content Et in the vinyl alcohol polymer, and is expressed as the following formula (2): 0.8<R+Et / 100 (2) The vinyl alcohol polymer according to claim 24 or 25, which satisfies the above formula:

28. The ratio of carbon-14 to total carbon is 1.0 x 10 －１４ This is the method for tracking a polymer using vinyl acetate.

29. The method for tracking a polymer using vinyl acetate according to claim 28, wherein the carbon stable isotope ratio of vinyl acetate is −20‰ or more.

30. The method for tracking a polymer using vinyl acetate according to claim 28, wherein the carbon stable isotope ratio of vinyl acetate is less than -20‰.

31. A method for tracking a polymer using a vinyl acetate polymer containing the vinyl acetate according to any one of claims 28 to 30 as a monomer unit.

32. A method for tracing a polymer using a vinyl alcohol polymer obtained by saponifying the vinyl acetate polymer according to claim 31.

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