Composition

Abstract

The present invention relates to a composition which comprises a poly(vinyl alcohol)-based resin (A) and a polyol (B1). The polyol (B1) has a glass transition temperature of 25°C or higher. The polyol (B1) is contained in an amount of 26-130 parts by mass per 100 parts by mass of the poly(vinyl alcohol)-based resin (A) and has a melting point of 210°C or lower and a crystallization temperature of 190°C or lower.

Description

composition

[0001] This patent application claims priority under the Paris Convention to Japanese Patent Application No. 2022-107890 (filing date: July 4, 2022), the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a composition that can be used as a packaging material for food, a melt-molded product containing the composition, a laminate that includes a layer containing the composition, and a food package that includes the laminate.

[0003] Polyvinyl alcohol resins are one of the few crystalline, water-soluble polymers that have been widely used in applications such as paper coating agents, paper internal additives, adhesives for paper, wood, and inorganic materials, warp sizing agents, stabilizers for emulsion polymerization and suspension polymerization, and various binders. Conventional polyvinyl alcohol resins have been used in the form of aqueous solutions due to their poor thermal stability. In other words, "fully saponified polyvinyl alcohol resins" have melting points and thermal decomposition temperatures that are very close to each other, making them impossible to process using hot melt molding. Meanwhile, "partially saponified polyvinyl alcohol resins," which have melting points lower than those of fully saponified polyvinyl alcohol resins, have poor thermal stability, resulting in the generation of an acetic acid odor during hot melt molding and poor gas barrier properties.

[0004] Also proposed are a method of blending a polyvinyl alcohol-based resin with another polymer or a plasticizer to reduce the melt viscosity of the polyvinyl alcohol-based resin and then hot-melt molding the polyvinyl alcohol-based resin (e.g., Patent Document 1), and a method of modifying a polyvinyl alcohol-based resin to reduce the melting point of the polyvinyl alcohol-based resin (e.g., Patent Document 2).

[0005] Patent No. 5645346 Patent No. 4772175

[0006] However, the method of blending a polyvinyl alcohol-based resin with another plasticizer, as in Patent Document 1, can cause problems such as bleeding of the plasticizer over long-term use and a decrease in gas barrier properties. Furthermore, modified polyvinyl alcohol-based resins such as those in Patent Document 2 have poor gas barrier properties when the degree of saponification is low, and poor melt moldability when the degree of saponification is high. Furthermore, when glycerin is used primarily as the plasticizer disclosed in Patent Document 2, there is a problem of decreased gas barrier properties. As such, it has been difficult to achieve both melt moldability and gas barrier properties in compositions containing polyvinyl alcohol-based resins.

[0007] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a composition having excellent gas barrier properties and melt-formability, a melt-formed product containing the composition, a laminate including a layer containing the composition, and food packaging including the laminate.

[0008] As a result of extensive research to achieve the above object, the present inventors have found that the above problems can be solved by setting the melting point and crystallization temperature within specific ranges in a composition containing a polyvinyl alcohol-based resin and a specific polyol in a predetermined ratio, and have thus completed the present invention.

[0009] [1] A composition comprising a polyvinyl alcohol-based resin (A) and a polyol (B1), wherein the polyol (B1) has a glass transition temperature of 25°C or higher, the content of the polyol (B1) is 26 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the polyvinyl alcohol-based resin (A), and the composition has a melting point of 210°C or lower and a crystallization temperature of 190°C or lower. [2] The composition according to [1], wherein the polyol (B1) has a crystallization enthalpy of 100 J / g or lower as measured by differential scanning calorimetry at a temperature decrease rate of 10°C / min. [3] The composition according to [1] or [2], wherein the polyol (B1) is at least one polyol selected from the group consisting of maltitol, lactitol, and trehalose. [4] The composition according to any one of [1] to [3], further comprising a polyol (B2) having a glass transition temperature of less than 25°C. [5] The composition according to [4], wherein the content of the polyol (B2) is 20 parts by mass or less per 100 parts by mass of the polyvinyl alcohol-based resin (A). [6] The composition according to any one of [1] to [3], wherein the polyol (B2) does not contain a polyol having a glass transition temperature of less than 25°C. [7] The composition according to any one of [1] to [6], wherein the content of the starch is 40 mass% or less based on the mass of the composition. [8] The composition according to any one of [1] to [6], wherein the starch is not contained. [9] The composition according to any one of [1] to [8], wherein the polyvinyl alcohol-based resin (A) contains a vinyl alcohol-based polymer having a degree of saponification of 90 mol% or more and 99.99 mol% or less.

[10] The composition according to any one of [1] to [9], wherein the viscosity-average degree of polymerization of the polyvinyl alcohol-based resin (A) is 200 or more and 1500 or less.

[11] The composition according to any one of [1] to

[10] , wherein the polyvinyl alcohol-based resin (A) contains an α-olefin-vinyl alcohol copolymer.

[12] The composition according to

[11] , wherein the α-olefin-vinyl alcohol copolymer contains a structural unit derived from an α-olefin having 4 or less carbon atoms.

[13] The composition according to any one of [1] to

[10] , wherein the polyvinyl alcohol-based resin (A) contains an ethylene-vinyl alcohol copolymer, and the ethylene unit content of the ethylene-vinyl alcohol copolymer is 1 mol% or more and 12 mol% or less.

[14] The composition according to

[13] , wherein the ethylene-vinyl alcohol copolymer content is 50 mass% or more relative to the mass of the polyvinyl alcohol-based resin (A).

[15] The oxygen transmission rate (OTR) is 3.0 cc / m. ２ The composition according to any one of claims [1] to

[14] , wherein the viscosity is 1 / day·atm or less.

[16] A melt-molded product comprising the composition according to any one of [1] to

[15] .

[17] A laminate comprising a layer containing the composition according to any one of [1] to

[15] .

[18] The laminate according to

[17] , wherein the laminate further comprises a layer containing a biodegradable polyester.

[19] The laminate according to

[18] , wherein the biodegradable polyester is at least one biodegradable polyester selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and polyhydroxyalkanoate.

[20] Food packaging comprising the laminate according to any one of

[17] to

[19] .

[0010] The composition of the present invention has excellent melt-processability and gas barrier properties.

[0011] [Composition] The composition of the present invention comprises a polyvinyl alcohol-based resin (A) and a polyol (B1), wherein the glass transition temperature (sometimes referred to as Tg) of the polyol (B1) is 25°C or higher, the content of the polyol (B1) is 26 to 130 parts by mass per 100 parts by mass of the polyvinyl alcohol-based resin (A), the melting point of the composition is 210°C or lower, and the crystallization temperature is 190°C or lower. In this specification, a polyol having a Tg of 25°C or higher may be referred to as "Tg≧25°C polyol (B1)" or "polyol (B1)," and the polyvinyl alcohol-based resin (A) may be simply referred to as "component (A)." In addition, in this specification, the upper and lower limits may be combined in any combination.

[0012] In conventional compositions containing polyvinyl alcohol-based resins, the addition of a plasticizer such as a polyol to improve melt moldability generally results in a decrease in crystallinity and a deterioration in gas barrier properties. However, the present inventors have surprisingly found that by adding 26 to 130 parts by mass of a polyol (B1) having a Tg of 25°C or higher per 100 parts by mass of the polyvinyl alcohol-based resin (A) and adjusting the melting point and crystallization temperature of the composition to 210°C or lower and 190°C or lower, respectively, not only is melt moldability improved, but the gas barrier properties can also be maintained or improved. Although the reason for this is unclear, it is presumed that the polyol (B1) suppresses the mobility of the amorphous portion of the polyvinyl alcohol-based resin.

[0013] <Polyvinyl Alcohol Resin (A)> The polyvinyl alcohol resin (A) includes a vinyl alcohol polymer. The vinyl alcohol polymer is a polymer containing vinyl alcohol units as monomer units. The vinyl alcohol polymer is obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer, which is the raw material monomer, and the saponified vinyl alcohol polymer may contain vinyl ester units in addition to vinyl alcohol units. The vinyl alcohol polymer may be a modified vinyl alcohol copolymer obtained by saponifying a copolymer obtained by copolymerizing the vinyl ester monomer, which is the raw material monomer, with another monomer, to contain monomer units other than vinyl alcohol units and vinyl ester units. In this specification, among the raw material monomers of such a modified vinyl alcohol copolymer, monomers other than vinyl ester monomers may be referred to as "modified species." Furthermore, the ratio of constituent units derived from the "modified species" to all monomer units in the modified vinyl alcohol copolymer may be referred to as the "modification amount." The modified vinyl alcohol polymer may be a so-called post-modified modified vinyl alcohol polymer in which a specific functional group is introduced into a saponified vinyl alcohol polymer by reacting a specific chemical species with the saponified vinyl alcohol polymer. In this specification, the term "vinyl alcohol polymer" includes unmodified vinyl alcohol polymers, modified vinyl alcohol copolymers, and post-modified vinyl alcohol polymers or copolymers. The polyvinyl alcohol resin (A) may also contain multiple types of vinyl alcohol polymers having different physical properties.

[0014] Examples of vinyl ester monomers used as raw material monomers for vinyl alcohol polymers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate, and among these, vinyl acetate is preferred.

[0015] The vinyl alcohol polymer may be a modified vinyl alcohol copolymer containing, in addition to vinyl alcohol units and vinyl ester units as described above, other monomer units other than the vinyl ester units. Examples of other monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylic acid and its salts; acrylic acid esters; methacrylic acid and its salts; methacrylic acid esters; acrylamide; acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or quaternary salts thereof, and N-methylolacrylamide and its derivatives; methacrylamide; methacrylamide derivatives such as N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts or quaternary salts thereof, and N-methylolmethacrylamide and its derivatives; methyl vinyl ether, ethyl vinyl ether, vinyl ethers such as n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinyl halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and salts or esters thereof; vinyl silyl compounds such as vinyltrimethoxysilane; isopropenyl acetate; and vinyl compounds such as dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerin monoallyl ether, and 3,4-diacetoxy-1-butene. Among these, from the viewpoint of easily improving gas barrier properties, the other monomer is preferably an α-olefin such as ethylene and / or 3,4-diacetoxy-1-butene. The content (modification amount) of these other monomer units varies depending on the purpose and application of use, etc.In one embodiment, the content of other monomer units may be preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and particularly preferably 0.5 mol% or less. In another embodiment, the content of other monomer units may be preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and preferably 12 mol% or less, more preferably 11 mol% or less, and even more preferably 10 mol% or less.

[0016] From the viewpoint of easily improving gas barrier properties, the polyvinyl alcohol resin (A) preferably contains, as the vinyl alcohol polymer, at least one selected from the group consisting of an unmodified vinyl alcohol polymer, an α-olefin-vinyl alcohol copolymer, and a vinyl alcohol copolymer having a 1,2-diol structure in the side chain; from the viewpoint of more easily improving gas barrier properties, it is more preferable that it contains an α-olefin-vinyl alcohol copolymer. The α-olefin-vinyl alcohol copolymer preferably contains a structural unit derived from an α-olefin having 4 or less carbon atoms, and is more preferably an ethylene-vinyl alcohol copolymer. Furthermore, the vinyl alcohol polymer contained in the polyvinyl alcohol resin (A) may be a vinyl alcohol polymer that does not contain an oxyalkylene group.

[0017] In one embodiment of the present invention, the degree of saponification of the polyvinyl alcohol-based resin (A) is preferably 90 mol% or more, more preferably 94 mol%, even more preferably 97 mol% or more, even more preferably 98 mol% or more, and preferably 99.9 mol% or less, more preferably 99.7 mol% or less, and even more preferably 99.5 mol% or less. When the degree of saponification of the polyvinyl alcohol-based resin (A) is within the above range, the crystallinity of the polyvinyl alcohol-based resin (A) is improved, the gas barrier properties are easily improved, and the water solubility is easily reduced. In addition, the thermal stability is improved, the melt moldability is easily improved, and molding and film formation are more stable. The degree of saponification of the polyvinyl alcohol-based resin can be measured in accordance with JIS K6726 (1994). When the polyvinyl alcohol resin (A) contains two or more vinyl alcohol polymers having different degrees of saponification, the degree of saponification of the mixture of vinyl alcohol polymers used is measured in accordance with JIS K6726 (1994), and the obtained degree of saponification is regarded as the degree of saponification of the polyvinyl alcohol resin (A).

[0018] In one embodiment of the present invention, the degree of saponification of the vinyl alcohol polymer contained in the polyvinyl alcohol resin (A) is preferably 90 mol% or more, more preferably 94 mol%, even more preferably 97 mol% or more, even more preferably 98 mol% or more, and preferably 99.9 mol% or less, more preferably 99.7 mol% or less, and even more preferably 99.5 mol% or less. When the degree of saponification of the vinyl alcohol polymer contained in the polyvinyl alcohol resin (A) is within the above range, the crystallinity of the polyvinyl alcohol resin (A) is improved, the gas barrier properties are easily improved, and the water solubility is easily reduced. In addition, the thermal stability is improved, the melt moldability is easily improved, and molding and film formation are more stable. The degree of saponification of the polyvinyl alcohol resin can be measured in accordance with JIS K6726 (1994).

[0019] In one embodiment of the present invention, when the polyvinyl alcohol resin (A) contains a vinyl alcohol polymer having a saponification degree of 90 mol% to 99.99 mol%, the content of the vinyl alcohol polymer having a saponification degree of 90 mol% to 99.99 mol% contained in the polyvinyl alcohol resin (A) is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 90 mass% or more, even more preferably 95 mass% or more, particularly preferably 98 mass% or more, and preferably 100 mass% or less, relative to the mass of the polyvinyl alcohol resin (A). Furthermore, the polyvinyl alcohol resin (A) may contain only a vinyl alcohol polymer having a saponification degree of 90 mol% to 99.99 mol%. When the content of the vinyl alcohol polymer having a saponification degree of 90 mol% to 99.99 mol% is equal to or greater than the above-mentioned lower limit, the gas barrier properties and melt moldability are easily improved.

[0020] In one embodiment of the present invention, when the polyvinyl alcohol-based resin (A) contains an ethylene-vinyl alcohol copolymer, the content (modification amount) of ethylene units in the polyvinyl alcohol-based resin (A) is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and preferably 12 mol% or less, more preferably 11 mol% or less, and even more preferably 10 mol% or less. When the ethylene unit content is within the above range, melt moldability and biodegradability are likely to be improved and water solubility is likely to be reduced while maintaining gas barrier properties. The ethylene unit content means the ratio of ethylene units to all monomer units in the ethylene-vinyl alcohol copolymer. The ethylene unit content is the ratio of the ethylene unit to the total monomer units in the ethylene-vinyl alcohol copolymer to the ethylene-vinyl ester copolymer, which is a precursor or reacetylated product of the ethylene-vinyl alcohol copolymer. １ It can be determined from H-NMR, for example, by the method described in the Examples. When the polyvinyl alcohol resin (A) contains a plurality of ethylene-vinyl alcohol copolymers having different ethylene unit contents, the ethylene unit contents of the mixture of ethylene-vinyl alcohol copolymers used are measured by the method described in the Examples, and the obtained ethylene unit content is defined as the ethylene unit content of the polyvinyl alcohol resin (A).

[0021] In one embodiment of the present invention, when the polyvinyl alcohol resin (A) contains an ethylene-vinyl alcohol copolymer, the ethylene unit content (modification amount) of the ethylene-vinyl alcohol copolymer is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and preferably 12 mol% or less, more preferably 11 mol% or less, and even more preferably 10 mol% or less. When the ethylene unit content is within the above range, melt moldability and biodegradability are likely to be improved and water solubility is likely to be reduced while maintaining gas barrier properties. The ethylene unit content means the ratio of ethylene units to all monomer units in the ethylene-vinyl alcohol copolymer. The ethylene unit content of the ethylene-vinyl alcohol copolymer is the ratio of the ethylene unit to the total monomer units in the ethylene-vinyl alcohol copolymer to the ethylene-vinyl ester copolymer, which is a precursor or reacetylated product of the ethylene-vinyl alcohol copolymer. １ It can be determined from H-NMR, for example, by the method described in the Examples.

[0022] Furthermore, the ethylene-vinyl alcohol copolymer may contain other monomer units in addition to vinyl alcohol units, ethylene units, and vinyl ester units, as long as the effects of the present disclosure are not impaired. Examples of other monomers include those other than the ethylene exemplified above, and the content of the other monomer units can be appropriately selected, for example, from the range of the former proportion (10 mol% or less) described above as the content of the other monomer units.

[0023] In one embodiment of the present invention, when the polyvinyl alcohol-based resin (A) contains an ethylene-vinyl alcohol copolymer, the content of the ethylene-vinyl alcohol copolymer is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, and particularly preferably 90% by mass or more, and is preferably 100% by mass or less, relative to the mass of the polyvinyl alcohol-based resin (A). When the content of the ethylene-vinyl alcohol copolymer is within the above range, melt moldability is likely to be improved and water solubility is likely to be reduced while maintaining gas barrier properties.

[0024] In one embodiment of the present invention, a vinyl alcohol copolymer having a 1,2-diol structure in its side chain is obtained, for example, by saponifying a copolymer obtained by copolymerizing a vinyl ester monomer and a 3,4-diacetoxy-1-butene monomer, and the saponified vinyl alcohol copolymer has a 1,2-diol structure in its side chain. The content of units containing a 1,2-diol structure in the vinyl alcohol copolymer having a 1,2-diol structure in its side chain is preferably 1 mol% or more, more preferably 2 mol% or more, even more preferably 3 mol% or more, and preferably 12 mol% or less, more preferably 11 mol% or less, and even more preferably 10 mol% or less. Having the content of units containing a 1,2-diol structure in the above ranges facilitates improved gas barrier properties, melt moldability, and biodegradability. The content of units containing a 1,2-diol structure refers to the ratio of units containing a 1,2-diol structure to all monomer units in the vinyl alcohol copolymer having a 1,2-diol structure in its side chain. The content of units containing 1,2-diol structures is １ It can be determined from H-NMR, for example, by the method described in the Examples.

[0025] Furthermore, the vinyl alcohol copolymer having a 1,2-diol structure in its side chain may contain other monomer units besides vinyl alcohol units, units derived from 3,4-diacetoxy-1-butene, and vinyl ester units, as long as the effects of the present disclosure are not impaired. Examples of other monomers include those other than the 3,4-diacetoxy-1-butene exemplified above, and the content of the other monomer units can be appropriately selected, for example, from the range of the former proportion (10 mol% or less) described above as the content of the other monomer units.

[0026] In one embodiment of the present invention, when the polyvinyl alcohol resin (A) contains a vinyl alcohol copolymer having a 1,2-diol structure in a side chain as the vinyl alcohol polymer, the content of the vinyl alcohol copolymer having a 1,2-diol structure in a side chain can be selected, for example, from the same range as the content of the ethylene-vinyl alcohol copolymer. When the content of the vinyl alcohol copolymer having a 1,2-diol structure in a side chain is within the above range, gas barrier properties and melt moldability are likely to be improved.

[0027] In one embodiment of the present invention, the polyvinyl alcohol-based resin (A) is preferably biodegradable. The biodegradable polyvinyl alcohol-based resin (A) can be decomposed into water and carbon dioxide by activated sludge treatment or by burying it in soil. For example, it is preferable that the biodegradable polyvinyl alcohol-based resin (A) be completely decomposed within two days when continuously treated with activated sludge. From the viewpoint of biodegradability, the polyvinyl alcohol-based resin (A) is preferably water-dispersible. When the polyvinyl alcohol-based resin (A) contains an ethylene-vinyl alcohol copolymer, the ethylene unit content of the ethylene-vinyl alcohol copolymer may be preferably 1 to 12 mol%, more preferably 1 to 10 mol%, and even more preferably 1 to 9 mol%, from the viewpoint of easily enhancing biodegradability.

[0028] In a preferred embodiment of the present invention, the polyvinyl alcohol resin (A) contains an ethylene-vinyl alcohol copolymer, and the ethylene unit content of the ethylene-vinyl alcohol copolymer is 1 mol % or more and 12 mol % or less. In this form, the gas barrier property, melt moldability, and biodegradability of the composition are likely to be improved.

[0029] In one embodiment of the present invention, the viscosity-average degree of polymerization (hereinafter sometimes abbreviated as "degree of polymerization") of the polyvinyl alcohol-based resin (A) is preferably 200 or more, more preferably 230 or more, even more preferably 250 or more, even more preferably 300 or more, and particularly preferably 350 or more. For example, it may be 400 or more or 450 or more, and preferably 1500 or less, more preferably 1200 or less, even more preferably 1000 or less, even more preferably 800 or less, for example, it may be 700 or less. When the degree of polymerization of the polyvinyl alcohol-based resin (A) is within the above range, it is easy to improve workability when producing molded products, films, etc., and it is easy to improve mechanical strength. Furthermore, it is easy to have good melt viscosity during melt molding, so it is easy to improve workability and processability. Furthermore, when the polyvinyl alcohol-based resin (A) contains two or more vinyl alcohol-based polymers, the degree of polymerization of the polyvinyl alcohol-based resin (A) means the average degree of polymerization calculated from the polymerization degrees and blending ratios of each vinyl alcohol-based polymer. When the polyvinyl alcohol resin (A) contains only one type of vinyl alcohol polymer, the degree of polymerization of the vinyl alcohol polymer is the degree of polymerization of the polyvinyl alcohol resin (A). When the polyvinyl alcohol resin (A) contains two or more types of vinyl alcohol polymers, vinyl alcohol polymers with different degrees of polymerization may be mixed in an appropriate blending ratio to adjust the degree of polymerization of the polyvinyl alcohol resin (A) to fall within the above-mentioned range. In this specification, the viscosity-average degree of polymerization can be measured in accordance with JIS K6726 (1994), for example, by the method described in the Examples.

[0030] In one embodiment of the present invention, the viscosity-average degree of polymerization of the vinyl alcohol polymer contained in the polyvinyl alcohol resin (A) may be 200 or more and 2000 or less, preferably 200 or more, more preferably 230 or more, even more preferably 250 or more, even more preferably 300 or more, and particularly preferably 350 or more, for example, 400 or more or 450 or more, and preferably 1800 or less, more preferably 1600 or less, even more preferably 1500 or less, even more preferably 1000 or less, and particularly preferably 800 or less, for example, 700 or less. When the viscosity-average degree of polymerization of the vinyl alcohol polymer is within the above range, it is easy to improve workability when producing molded products, films, etc., and it is easy to improve mechanical strength. In addition, it is easy to have a good melt viscosity during melt molding, so it is easy to improve workability and processability.

[0031] In one embodiment of the present invention, the content of the polyvinyl alcohol-based resin (A) is preferably 43% by mass or more, more preferably 45% by mass, and may be, for example, 48% by mass or more, 51% by mass or more, or 56% by mass or more, relative to the mass of the composition, and is preferably 79% by mass or less, more preferably 74% by mass or less, even more preferably 70% by mass or less, still more preferably 65% ​​by mass or less, or 62% by mass or less. When the content of the polyvinyl alcohol-based resin (A) is equal to or more than the above lower limit, the gas barrier property is easily improved, and when the content of the polyvinyl alcohol-based resin (A) is equal to or less than the above upper limit, the melt moldability is easily improved.

[0032] <Method for Producing Polyvinyl Alcohol Resin (A)> As described above, the polyvinyl alcohol resin (A) contains a vinyl alcohol polymer. The vinyl alcohol polymer can be obtained, for example, by polymerizing a vinyl ester monomer, or a vinyl ester monomer and another monomer, to obtain a vinyl ester polymer or copolymer (the polymer and copolymer may be collectively referred to as a vinyl ester polymer), followed by saponification. Methods for polymerizing vinyl ester monomers include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among these, bulk polymerization and solution polymerization, in which polymerization is performed without a solvent or in a solvent such as alcohol, are preferably used. Examples of alcohols used as a solvent during solution polymerization include lower alcohols such as methanol, ethanol, and propanol. Examples of initiators used in copolymerization include known initiators such as azo initiators or peroxide initiators, such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethyl-valeronitrile), benzoyl peroxide, and n-propyl peroxydicarbonate. The polymerization temperature is not particularly limited, but is preferably in the range of 0°C to 150°C. Furthermore, for example, when the vinyl alcohol polymer is an ethylene-vinyl alcohol copolymer or the like, it is preferable to copolymerize a vinyl ester monomer with a monomer such as ethylene by the above method.

[0033] The vinyl ester polymer obtained in the polymerization step can be saponified in an organic solvent by alcoholysis or hydrolysis in the presence of a catalyst. Examples of catalysts used in the saponification step include basic catalysts such as sodium hydroxide, potassium hydroxide, and sodium methoxide; or acidic catalysts such as sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid. The organic solvent used in the saponification step is not particularly limited, but examples include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. These can be used alone or in combination. Among these, it is preferable to use methanol or a mixed solution of methanol and methyl acetate as the solvent and carry out the saponification reaction in the presence of sodium hydroxide, a basic catalyst, for simplicity's sake. The amount of saponification catalyst used is preferably 0.001 to 0.5 in molar ratio to the vinyl ester monomer units in the vinyl ester polymer. This molar ratio is more preferably 0.002 or greater. On the other hand, this molar ratio is more preferably 0.4 or less, and even more preferably 0.3 or less.

[0034] A preferred embodiment of the saponification step is as follows. First, a saponification catalyst such as sodium hydroxide is added to the vinyl ester polymer solution obtained in the polymerization step and mixed. The solvent used here is preferably methanol. Initially, the mixture is a homogeneous liquid. However, as the saponification reaction progresses and the vinyl ester units in the polymer are saponified and converted to vinyl alcohol units, the solubility in the solvent decreases, causing the polymer to precipitate in the solution. At this time, the solution contains methyl acetate produced by alcoholysis with methanol. As the saponification reaction progresses, the amount of polymer precipitated gradually increases, forming a slurry, which then loses fluidity. Therefore, to ensure that the saponification reaction proceeds uniformly, it is preferable to mix thoroughly until fluidity is lost.

[0035] The method for mixing the vinyl ester polymer solution and the saponification catalyst is not particularly limited, and various methods such as a static mixer, a kneader, or a stirring blade can be used, but the use of a static mixer is preferred because it allows continuous, uniform mixing. In this case, it is preferable to add the saponification catalyst to the vinyl ester polymer solution after the polymerization step in a pipe connected to the polymerization tank, and then pass the mixture through a static mixer to mix and obtain a paste. The temperature of the reaction solution in the static mixer is usually 20 to 80°C.

[0036] The method for promoting the saponification reaction of the vinyl ester polymer in the paste that has passed through the static mixer is not particularly limited. A preferred method is to place the paste on a moving belt and promote the saponification reaction while moving the belt in a tank maintained at a constant temperature. The paste on the belt loses its fluidity and becomes solid, and the saponification reaction then proceeds in the solid state. This method allows the saponification reaction to proceed continuously in the solid state, resulting in a solid block containing the vinyl alcohol polymer and the solvent. The saponification temperature is preferably 20 to 60°C, preferably 25°C or higher, more preferably 30°C or higher, and preferably 55°C or lower, more preferably 50°C or lower. A saponification temperature above the lower limit mentioned above can easily prevent a decrease in the reaction rate. A saponification temperature below the upper limit mentioned above can easily prevent a decrease in the solvent content in the resulting solid block and a deterioration in the solubility of the resulting vinyl alcohol polymer. The saponification time is preferably 5 minutes to 2 hours. The saponification time is more preferably 8 minutes or longer, even more preferably 10 minutes or longer, more preferably 1.5 hours or shorter, and even more preferably 1 hour or shorter.

[0037] If necessary, a washing step may be added to wash the vinyl alcohol polymer for the purpose of removing impurities such as sodium acetate. Examples of washing liquids include methanol, acetone, methyl acetate, ethyl acetate, hexane, and water. Among these, methanol, methyl acetate, and water, alone or in combination, are more preferred. The amount of washing liquid is typically preferably 30 to 10,000 parts by mass, and more preferably 50 to 3,000 parts by mass, per 100 parts by mass of the vinyl alcohol polymer. The washing temperature is preferably 5 to 80°C, and more preferably 20 to 70°C. The washing time is preferably 20 minutes to 10 hours, and more preferably 1 to 6 hours. Known washing methods, such as a batch method and a countercurrent washing method, can be used.

[0038] <Polyol (B1)> The composition of the present invention contains a polyol (B1) having a Tg of 25°C or higher, and the content of the polyol (B1) is 26 parts by mass or more and 130 parts by mass or less per 100 parts by mass of the polyvinyl alcohol-based resin (A). If the content of the polyol (B1) is less than 26 parts by mass or more than 130 parts by mass, the melt-moldability and / or gas barrier properties are insufficient. In the present invention, since the content of the polyol (B1) is within the above range, the melting point of the composition is lowered to improve the melt-moldability, while maintaining or improving the gas barrier properties. The polyol (B1) can be used alone or in combination of two or more types.

[0039] The Tg of the polyol (B1) is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and even more preferably 70°C or higher, and is preferably 150°C or lower, more preferably 130°C or lower. When the Tg of the polyol (B1) is within the above range, the crystallization temperature of the composition is high and the composition has heat resistance, which makes it easy to improve melt moldability and gas barrier properties. The Tg of the polyol (B1) can be measured using a differential scanning calorimeter (sometimes referred to as DSC), for example, by the method described in the examples.

[0040] The crystallization enthalpy of polyol (B1) is preferably 100 J / g or less, more preferably 50 J / g or less, even more preferably 30 J / g or less, and even more preferably 5 J / g or less. When the crystallization enthalpy of polyol (B1) is within the above range, bleed-out of polyol (B1) is easily suppressed. Here, the crystallization enthalpy in the present invention is measured using a differential scanning calorimeter at a temperature decrease rate of 10°C / min, and can be measured, for example, by the method described in the Examples. Note that, if the crystallization enthalpy of a polyol is indistinguishable under these measurement conditions, the crystallization enthalpy is considered to be 0 J / g, and such a polyol also falls under the category of polyols having a crystallization enthalpy of 100 J / g or less. Note that the crystallization enthalpy being indistinguishable means that it cannot be determined because no crystallization enthalpy peak is present in the DSC measurement.

[0041] The polyol (B1) is not particularly limited as long as it has a Tg of 25°C or higher, is compatible with the polyvinyl alcohol-based resin (A), and has the effect of lowering the melting point of the composition, but suitable examples include polyhydric alcohols such as maltitol, lactitol, and trehalose. From the viewpoint of easily improving melt-processability and gas barrier properties, the polyol (B1) is preferably at least one selected from the group consisting of maltitol, lactitol, and trehalose, and more preferably trehalose.

[0042] The content of polyol (B1) is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 45 parts by mass or more, per 100 parts by mass of polyvinyl alcohol-based resin (A), and may be, for example, 51 parts by mass or more, 55 parts by mass or more, or 60 parts by mass or more, and is preferably 140 parts by mass or less, more preferably 130 parts by mass or less, and may be, for example, 120 parts by mass or less, 105 parts by mass or less, 95 parts by mass or less, 85 parts by mass or less, or 80 parts by mass or less. When the content of polyol (B1) is at least the above lower limit, the melt-moldability and gas barrier properties of the composition are easily improved, and when the content of polyol (B1) is at most the above upper limit, the occurrence of problems such as bleed-out of polyol (B1) can be suppressed, and the melt-moldability and gas barrier properties of the composition are easily improved.

[0043] <Polyol (B2)> The composition of the present invention may contain, in addition to the polyol (B1), a polyol (B2) (sometimes simply referred to as polyol (B2)) having a Tg of less than 25° C., as long as the effects of the present invention are not impaired. The polyol (B2) may be used alone or in combination of two or more types.

[0044] From the viewpoint of imparting flexibility to the composition, the Tg of the polyol (B2) is preferably 20° C. or lower, more preferably 15° C. or lower, even more preferably 10° C. or lower, still more preferably 5° C. or lower, and is preferably −100° C. or higher, more preferably −80° C. or higher, even more preferably −60° C. or higher, still more preferably −40° C. or higher, and particularly preferably −20° C. or higher. The Tg of the polyol (B2) can be measured using DSC, for example, by the method described in the Examples.

[0045] The polyol (B2) is not particularly limited as long as it is a compound that can reduce the Tg or melt viscosity of the polyvinyl alcohol-based resin (A), and examples thereof include polyhydric alcohols such as sorbitol, xylitol, glycerin, and diglycerin; diols such as 1,3-butanediol and 2,3-butanediol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and propylene glycol; glycerin derivatives obtained by adding ethylene oxide, propylene oxide, or the like to polyhydric alcohols such as sorbitol, xylitol, glycerin, and diglycerin; sugars; polyethers; phenol derivatives such as bisphenol A and bisphenol S; amide compounds such as N-methylpyrrolidone; trimethylolpropane, diglycerin, and 3-methyl-1,3,5-pentanetriol. These may be used alone or in combination. Among these, polyhydric alcohols are preferred, at least one selected from the group consisting of sorbitol, xylitol and glycerin is preferred, sorbitol and / or glycerin is more preferred, and sorbitol is even more preferred.

[0046] In one embodiment of the present invention, the content of polyol (B2) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the polyvinyl alcohol-based resin (A). When the content of polyol (B2) is equal to or less than the above-mentioned upper limit, good gas barrier properties are likely to be exhibited. Furthermore, the lower limit of the content of polyol (B2) may be, for example, 0 parts by mass or more, 0.1 parts by mass or more, or 1 part by mass or more. In another embodiment of the present invention, from the viewpoint of easily improving gas barrier properties, it is preferable that the composition of the present invention does not contain polyol (B2).

[0047] <Polyol (B3)> As a polyol other than the above-mentioned polyol (B1) and polyol (B2), there is a polyol (B3) whose Tg is not observed by DSC measurement. Examples of polyol (B3) include mannitol, pentaerythritol, and dipentaerythritol. Such polyol (B3) does not fall under the category of polyol (B1) or polyol (B2).

[0048] In addition, all polyols contained in the composition of the present invention may be collectively referred to as polyol (B). In one embodiment of the present invention, the content of polyol (B1) is preferably 70% by mass or more, more preferably 80% by mass or more, and may be, for example, 90% by mass or more, 95% by mass or more, or 98% by mass or more, relative to the mass of polyol (B). The upper limit of the content of polyol (B1) is 100% by mass or less. In another embodiment of the present invention, polyol (B) may be composed solely of polyol (B1). When the content of polyol (B1) relative to the mass of polyol (B) is equal to or greater than the above-mentioned lower limit, the gas barrier properties of the composition are likely to be improved.

[0049] <Composition> The composition of the present invention contains the polyvinyl alcohol-based resin (A) and 26 parts by mass or more and 130 parts by mass or less of the polyol (B1) per 100 parts by mass of the component (A), and has a melting point of 210° C. or less and a crystallization temperature of 190° C. or less, thereby achieving both excellent gas barrier properties and excellent melt-moldability.

[0050] If the melting point of the composition of the present invention is higher than 210°C and / or the crystallization temperature is higher than 190°C, the gas barrier properties and / or melt moldability tend to be insufficient. The melting point of the composition of the present invention is 210°C or lower, preferably 208°C or lower, more preferably 206°C or lower, and even more preferably 205°C or lower, and may be, for example, 204°C or lower or 203°C or lower. If the melting point is lower than the above upper limit, the gas barrier properties and melt moldability of the composition can be improved, and the strength of molded articles formed from the composition can also be increased. In addition, co-extrusion / co-injection molded articles with biodegradable polyesters having low heat resistance can be stably produced. The melting point of the composition of the present invention is preferably 160°C or higher, more preferably 170°C or higher, even more preferably 172°C or higher, and even more preferably 173°C or higher, and may be, for example, 180°C or higher or 190°C or higher. If the melting point is lower than the above upper limit or higher than the above lower limit, the above-mentioned effects (gas barrier properties, melt moldability, heat resistance, strength, and stability) are more likely to be improved. The melting point of the composition is the temperature at which tan δ becomes greater than 1 in the process of lowering the temperature from 230°C to 160°C and then raising the temperature from 160°C to 230°C at a rate of 5°C / min using a dynamic viscoelasticity apparatus under nitrogen at a frequency of 1 Hz, and can be measured, for example, by the method described in the Examples.

[0051] The crystallization temperature of the composition of the present invention is 190°C or lower, preferably 188°C or lower, more preferably 186°C or lower, and may be, for example, 184°C or lower. When the crystallization temperature is below the above-mentioned upper limit, the gas barrier properties and melt moldability of the composition can be improved, and the strength of molded articles formed from the composition can also be increased. Furthermore, co-extrusion and co-injection molded articles with biodegradable polyesters having low heat resistance can be stably produced. The crystallization temperature of the composition of the present invention is preferably 120°C or higher, more preferably 122°C or higher, and even more preferably 124°C or higher, and may be, for example, 150°C or higher or 170°C or higher. When the crystallization temperature is below the above-mentioned upper limit or above the above-mentioned lower limit, the above-mentioned effects (gas barrier properties, melt moldability, heat resistance, strength, and stability) are more likely to be improved. The crystallization temperature of the composition is the temperature at which tanδ becomes 1 or less during the process of decreasing the temperature from 230°C to 160°C at a rate of 5°C / min under nitrogen and at a frequency of 1 Hz using a dynamic viscoelasticity apparatus, and can be measured, for example, by the method described in the Examples.

[0052] The melting point and crystallization temperature of the composition can be adjusted by appropriately adjusting the type and content of the polyol (B), the type, polymerization degree, modification amount, saponification degree and content of the polyvinyl alcohol-based resin (A), etc., and the melting point and crystallization degree may be adjusted by using the above-mentioned preferred ones or setting them within the preferred ranges. For example, the melting point and crystallization degree tend to decrease as the contents of the polyol (B1) and polyol (B2) increase and as the polymerization degree of the polyvinyl alcohol-based resin (A) decreases.

[0053] In one embodiment of the present invention, the composition of the present invention can have a low melt viscosity. The complex viscosity of the composition of the present invention is preferably 10,000 Pa·s or less, more preferably 5,000 Pa·s or less, and even more preferably 3,000 Pa·s or less. For example, it may be 2,000 Pa·s or less, 1,500 Pa·s or less, 1,000 Pa·s or less, or 600 Pa·s or less. The complex viscosity of the composition of the present invention is preferably 70 Pa·s or more, more preferably 90 Pa·s or more. When the complex viscosity is within the above range, melt moldability is easily improved. For example, when the complex viscosity is below the above upper limit, extrusion, injection, and compression moldability are easily improved, and when the complex viscosity is above the above lower limit, coextrusion moldability is also easily improved. The complex viscosity can be measured using a dynamic viscoelasticity apparatus under nitrogen, at a frequency of 1 Hz, and at a temperature of 200°C, for example, by the method described in the examples.

[0054] The composition of the present invention has significantly superior gas barrier properties, particularly oxygen barrier properties, compared to conventional polyvinyl alcohol-based resin compositions, and is useful as a resin for oxygen barrier films. That is, the composition of the present invention has a lower oxygen permeability, which is an index of oxygen barrier properties, measured by the specific method shown below, compared to conventional polyvinyl alcohol-based resin compositions. In one embodiment of the present invention, the oxygen permeability (OTR) of the composition of the present invention is preferably 3.0 cc / m ２ ·day·atm or less, more preferably 3.0 cc / m ２ Less than 2.5 cc / m ２ ·day·atm or less, and even more preferably 2.0 cc / m ２ ·day·atm or less, particularly preferably 1.5 cc / m ２ less than 1.0 cc / m ２ ·day·atm or less, particularly preferably 0.8 cc / m ２ When the oxygen transmission rate (OTR) is equal to or less than the upper limit, excellent oxygen barrier properties can be exhibited. The oxygen transmission rate is measured by soaking an aqueous solution of the composition in a double-bleached kraft paper (100 μm thick, 70 g / m ２The resulting barrier paper (a laminate of paper and a composition layer) was conditioned at a temperature of 23°C and a relative humidity of 65% for 7 days, and the oxygen permeability (unit: cc / m) of the barrier paper was then measured. ２ ·day·atm) is measured and the obtained measured value is converted into a value corresponding to a thickness of 20 μm of the composition layer, and can be measured, for example, by the method described in the Examples.

[0055] The composition of the present invention has excellent melt moldability, so that it can be molded while suppressing film thickness unevenness even at a relatively low molding temperature.In addition, it can be applied to various known molding methods (e.g., compression molding, extrusion molding, injection molding, etc.).For example, it can also be suitably applied to co-extrusion molding, and a laminate can be formed by co-extrusion molding together with a layer containing a biodegradable polyester.In this specification, melt moldability means a property that is easy to melt mold, and the higher the melt moldability, the easier it is to melt mold.For example, melt moldability can be evaluated by compression molding and extrusion molding as in the examples.

[0056] (Additives) The composition of the present invention may further contain starch. The starch may be unmodified or modified. Inclusion of unmodified and / or modified starch is preferred from the viewpoints of reducing the material cost of the composition and improving biodegradability. Examples of starch include starches derived from corn, cassava, potato, sweet potato, sago, tapioca, sorghum, beans, bracken, lotus, water chestnut, wheat, rice, oats, arrowroot, and peas. Among these, from the viewpoint of amylose content, starch derived from corn (maize) or cassava is preferred, and starch derived from corn is more preferred. The starch may be composed of one or more types of starch. The modified starch may contain a modified group in which a hydroxyl group contained in the starch is modified with a hydrophilic compound and / or a hydrophobic compound, and is preferably etherified starch, esterified starch, or amidated starch.

[0057] Examples of the hydrophilic compound include alkylene oxides having 2 to 6 carbon atoms, such as ethylene oxide, propylene oxide, and butylene oxide; halogenated carboxylic acids having 2 to 4 carbon atoms, such as chloroacetic acid; alkyl halides having 2 to 6 carbon atoms, such as methyl bromide; carboxylic anhydrides having 2 to 6 carbon atoms, such as maleic anhydride and phthalic anhydride; oxoacid salts, such as sodium nitrate and sodium phosphate; 2-diethylaminoethyl chloride; and 2,3-epoxypropyltrimethylammonium chloride.

[0058] Examples of the hydrophobic compound include cetyl bromide, lauryl bromide; epoxidized soybean fatty alcohol, epoxidized linseed fatty alcohol; glycidyl ethers having 2 to 24 carbon atoms, such as allyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, decane glycidyl ether, lauryl phenyl glycidyl ether, myristoyl glycidyl ether, cetyl glycidyl ether, palmityl glycidyl ether, stearyl glycidyl ether, and linolyl glycidyl ether; and glycidyl ethers having 2 to 24 carbon atoms, such as octanoic acetic anhydride, decanoic acetic anhydride, and lauric acid. Examples of suitable amines include alkanoic carboxylic acid anhydrides such as acetic anhydride and myristic acetic anhydride; alkyl or alkenyl dicarboxylic acid anhydrides such as alkyl or alkenyl succinic anhydride and alkyl or alkenyl maleic anhydride; and aliphatic amines containing a saturated or unsaturated hydrocarbon group having 6 to 24 carbon atoms (for example, n-dodecylamine, n-hexadecylamine, n-octadecylamine, cocoamine, tallow amine, hydrogenated N-tallow-1,3-diaminopropane, N-hydrogenated tallow-1,3-diaminopropane, N-oleyl-1,3-diaminopropane, etc.).

[0059] In one embodiment of the present invention, from the viewpoint of easily adjusting the melting point and degree of crystallinity of the composition and easily enhancing the gas barrier properties, the starch content may be preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to the mass of the composition. The lower limit of the starch content may be, for example, 0% by mass or more, 0.1% by mass or more, or 1% by mass or more. In another embodiment of the present invention, from the viewpoint of easily adjusting the melting point and degree of crystallinity of the composition and easily enhancing the gas barrier properties, it is preferable that the composition of the present invention does not contain starch.

[0060] The composition of the present invention may contain additives other than the polyvinyl alcohol resin (A), polyol (B), and starch, as long as they do not impair the objectives and effects of the present invention. Examples of such additives include inorganic layered compounds, fillers, processing stabilizers such as copper compounds, weathering stabilizers, colorants, UV absorbers, heat stabilizers, light stabilizers, antioxidants, antistatic agents, flame retardants, plasticizers other than the above-mentioned polyols, other plasticizer resins, lubricants, fragrances, foaming agents, deodorants, extenders, release agents, mold release agents, reinforcing materials, antifungal agents, preservatives, crystallization rate retarders, and other thermoplastic resins other than the polyvinyl alcohol resin (A). Adding organic stabilizers such as hindered phenols, copper halide compounds such as copper iodide, and alkali metal halide compounds such as potassium iodide as heat stabilizers is particularly preferred, as they improve melt retention stability during molding and fiberization. The composition of the present invention may or may not contain the above-mentioned additives. The content of the other additives is not particularly limited, but may be preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, for example, 1.5% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less, or 0.01% by mass or less, relative to the mass of the composition. The content of the other additives may be the total content (total proportion) of all the other additives, or may be the content (proportion) of one specific other additive selected from the other additives, or may be the total content (proportion) of two or more specific other additives selected.

[0061] Examples of inorganic layered compounds include micas, talc, montmorillonite, kaolinite, vermiculite, etc. Addition of an inorganic layered compound tends to improve gas barrier properties, strength, and handleability.

[0062] The filler preferably increases hardness and rigidity, imparts a sense of mass, exhibits anti-blocking properties, and further exerts effects of controlling the rate of water disintegration and biodegradability of the resulting molded product or fiber. Examples of fillers include inorganic fillers such as kaolin, clay, talc, acid clay, silica, alumina, diatomaceous earth, bentonite, montmorillonite, kibushi clay, gairome clay, rosewood, alumite, china clay, feldspar, asbestos, perlite, calcium carbonate, magnesium hydroxide, carbon black, titanium oxide, mica, zirconium oxide, boron nitride, aluminum nitride, shirasu, glass, and glass fiber, and organic fillers such as urea-formalin-based resins and melamine-formalin-based resins. The average particle size of the filler is not particularly limited, but is preferably 0.1 to 100 μm. The content of the filler is not particularly limited, but is preferably 400 parts by mass or less, and more preferably 200 parts by mass or less, per 100 parts by mass of the polyvinyl alcohol-based resin (A).

[0063] In one embodiment of the present invention, the total content of the polyvinyl alcohol-based resin (A), the polyol (B1), and optionally the polyol (B2), particularly the total content of the polyvinyl alcohol-based resin (A) and the polyol (B1), is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably 95% by mass or more, and particularly preferably 98% by mass or more, and may even be 100% by mass, relative to the mass of the composition. When the total content is within the above range, the gas barrier properties and melt moldability of the composition are likely to be improved.

[0064] The method for producing the composition of the present invention is not particularly limited, and may be, for example, a method of mixing a polyvinyl alcohol-based resin (A), a polyol (B1), and optionally a polyol (B2), the starch, and the other additives. The order of mixing is not particularly limited, and for example, starch and / or other additives may be added to the polyvinyl alcohol-based resin (A) and then the polyol (B) may be added, or vice versa, or all components may be added simultaneously. Mixing can be performed using a known mixer, and preferably a melt-kneader. In a preferred embodiment of the present invention, the composition is obtained by melt-kneading using an extruder. The form of the composition is not particularly limited, and may be pellets, a sheet, or a film.

[0065] As the extruder, for example, a twin-screw extruder can be used. The twin-screw extruder may be either co-rotating or counter-rotating. The screw rotation speed is preferably 20 rpm or more, more preferably 40 rpm or more. The cylinder temperature is 100°C or more, more preferably 150°C or more, even more preferably 200°C or more, and preferably 300°C or less. Each component can be directly introduced into the extruder. Alternatively, these components may be premixed using a mixer or the like and then introduced into the extruder.

[0066] The molten mixture that has been forced through the extruder while being melt-kneaded is extruded through a die, the temperature of which may preferably be 150 to 250°C.

[0067] The extruded mixture (melt) can be extruded into a sheet, film or strand shape, and in this case, the mixture (melt) is cooled and dried.

[0068] When the mixture is extruded into strands, it can be extruded through a strand nozzle with multiple holes and cut with a rotary cutter to form pellets. To prevent the pellets from sticking together, vibration can be applied periodically or constantly, and moisture in the pellets can be removed using hot air, dehumidified air, or an infrared heater.

[0069] When the mixture is extruded into a sheet or film, the mixture can be extruded through a film-forming die and then cooled and dried while being taken up by a take-up roller. Cooling between the die and the roller is preferred to prevent the mixture from sticking to the roller.

[0070] In one embodiment of the present invention, the thickness of a film or sheet comprising the composition of the present invention is not particularly limited, but is preferably 5 to 1000 μm, more preferably 10 to 500 μm. The thickness of the film or sheet can be measured using a thickness meter, for example, by the method described in the Examples.

[0071] The composition of the present invention may contain a solvent and may be in the form of a solution or dispersion. As the solvent, a known solvent capable of dissolving or dispersing the components in the composition can be used. In addition, the solution or dispersion of the composition may be formed into a sheet or film by a conventional film-forming method (e.g., cast film formation, etc.).

[0072] [Melt-molded article] The present invention encompasses a melt-molded article containing the composition of the present invention. The melt-molded article (or melt-molded product) of the present invention has excellent gas barrier properties because it contains the composition of the present invention. Examples of melt-molding methods include extrusion molding, injection molding, T-die extrusion film formation, inflation film formation, compression molding, transfer molding, reinforced plastic molding, hollow molding, press molding, blow molding, calendar molding, foam molding, vacuum molding, and pressure molding. If desired, other thermoplastic resins can be laminated by methods such as coextrusion molding and lamination molding. These methods can produce molded articles of any shape, such as films, sheets, tubes, bottles, nonwoven fabrics, and fibers. In one embodiment of the present invention, for example, when compression molding is used, a pelletized composition can be molded into the desired shape using a compression molding machine. In this case, the composition of the present invention has excellent melt moldability, allowing molding at relatively low temperatures.

[0073] [Laminate] The present invention encompasses a laminate including a layer containing the composition of the present invention (sometimes referred to as a composition layer). The laminate of the present invention has excellent gas barrier properties because it contains the composition of the present invention.

[0074] The laminate of the present invention may contain one or more layers of the composition of the present invention. When two or more layers are contained, the compositions of the respective composition layers may be the same or different. The laminate may contain layers other than the composition layer of the present invention. Examples of such layers include paper, polymer film layers, adhesive layers, etc. The paper is not particularly limited, and examples thereof include kraft paper, double-bleached kraft paper, wood-free paper, construction paper, glassine paper, parchment paper, synthetic paper, white cardboard, manila cardboard, milk carton base paper, cup base paper, ivory paper, and silver paper.

[0075] The polymer constituting the polymer film layer is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET); polyolefins such as polypropylene (PP) [preferably biaxially oriented polypropylene (BOPP)] and polyethylene (PE) [preferably low-density polyethylene (LDPE), high-density polyethylene (HDPE), and linear low-density polyethylene (LLDPE)]; ethylene-vinyl acetate copolymers; ethylene-α-olefin copolymers; ionomers; polyamides; polyimides; biodegradable polyesters; and resins obtained by modifying these with modifiers such as maleic anhydride. Among these, biodegradable polyesters are preferred from the viewpoint of biodegradability. The biodegradable polyester is preferably at least one biodegradable polyester selected from the group consisting of polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), and polyhydroxyalkanoate (PHA).

[0076] Examples of the layer configuration of the laminate of the present invention include paper / composition layer; polymer film / composition layer; polymer film / composition layer / polymer film; paper / adhesive layer / composition layer; polymer film / adhesive layer / composition layer; polymer film / adhesive layer / composition layer; polymer film / adhesive layer / composition layer / paper / adhesive layer / polymer film.

[0077] Methods for producing the laminate of the present invention include a method of forming a film of the composition on another layer such as paper or a polymer film, a method of co-extruding a composition layer with another layer, a method of laminating or co-extrusion forming a film of the composition layer, an adhesive layer and another layer, etc. When laminating, the adhesive may be applied to the surface of the other layer or extrusion coated on the surface of the other layer.

[0078] In one embodiment of the present invention, the laminate of the present invention has a biodegradable polyester layer / composition layer / biodegradable polyester layer in this order. Such a laminate can be obtained by co-extruding a pellet-shaped composition using a co-extruder. In another embodiment of the present invention, the laminate of the present invention has a paper / composition layer in this order. Such a laminate can be obtained by forming a film on paper using a conventional film-forming machine and drying it.

[0079] In one embodiment of the present invention, a crosslinking agent may be added to the composition of the present invention when obtaining the laminate of the present invention. Examples of crosslinking agents include epoxy compounds, isocyanate compounds, aldehyde compounds, silica compounds, aluminum compounds, zirconium compounds, and boron compounds. Among these, silica compounds such as colloidal silica and alkyl silicates are preferred. The amount of crosslinking agent added may be 5 to 60 parts by mass, preferably 10 to 40 parts by mass, and more preferably 15 to 30 parts by mass, per 100 parts by mass of the polyvinyl alcohol-based resin (A).

[0080] In one embodiment of the present invention, a heat-sealable resin layer may be formed as another layer on the composition layer. The heat-sealable resin layer is typically formed by coextrusion, extrusion lamination, or dry lamination. Examples of heat-sealable resins that can be used include polyethylenes such as HDPE, LDPE, and LLDPE, PP, ethylene-vinyl acetate copolymers, ethylene-α-olefin copolymers, and ionomers, as well as biodegradable polyesters such as PLA, PBS, PHA, and PBAT, and resins obtained by modifying these with a modifier such as maleic anhydride.

[0081] In one embodiment of the present invention, the laminate of the present invention may be subjected to a stretching treatment for the purpose of improving oxygen barrier properties and mechanical properties. For example, in the case of a laminate of a polymer film such as a polyolefin film, a polyester film, or a polyamide film with a composition layer, the manufacturing conditions are not particularly limited, but the laminate is usually heat-treated in air or the like at a temperature applied to the resin constituting the polymer film. The heat treatment temperature may be, for example, 140°C to 170°C in the case of a polyolefin film, and 140°C to 240°C in the case of a polyester film or a polyamide film. The heat treatment of the composition layer is preferably performed simultaneously with the heat treatment of the polymer film.

[0082] In one embodiment of the present invention, the thickness of the composition layer in the laminate of the present invention can be appropriately selected depending on the number of layers and the types of other layers, and is not particularly limited, but may be preferably 5 to 500 μm, more preferably 5 to 300 μm, even more preferably 7 to 150 μm, and still more preferably 10 to 100 μm. When the laminate of the present invention has a plurality of composition layers, the thickness of the composition layer described above refers to the thickness of one composition layer.

[0083] In one embodiment of the present invention, the thickness of the laminate of the present invention can be appropriately selected depending on the number and type of layers and is not particularly limited, but may be preferably 10 to 2000 μm, more preferably 20 to 1000 μm. The thicknesses of the composition layers in the laminate and the laminate can each be measured using a thickness meter, for example, by the method described in the Examples.

[0084] [Uses] The composition of the present invention can be used, for example, as a fiber sizing agent, a fiber treatment agent, a fiber processing agent, a sizing agent for textile products, a paper processing agent such as a clear coating agent for paper, a pigment coating agent for paper, an internal sizing agent for paper, or a binder for overcoating thermal paper, a pressure-sensitive adhesive, an anti-fogging agent, a paint, an adhesive for paper, wood, or plastic, a binder for nonwoven fabric, a binder for fiber, a binder for ceramics, a binder for various building materials such as gypsum board or fiberboard, an additive for cement or mortar, a hot-melt adhesive, an image-forming material, a photosensitive resin, a substrate for gel, a film, a fiber, a sheet, a molded article (film, fiber, sheet, tube, nonwoven fabric, etc.), a soil conditioner, etc. The composition of the present invention may also be used in combination with other polymers such as cellulose derivatives, gums, gelatin, or casein.

[0085] The present invention includes food packaging comprising the laminate of the present invention. The food packaging is not particularly limited, but examples thereof include containers for packaging foods such as meat, fresh noodles, processed foods, tea, coffee powder, coffee beans, and pickles.

[0086] As one embodiment of the present invention, from the viewpoint of suitability for the above-mentioned applications, the composition of the present invention is preferably low in water solubility, and for example, it is preferable that a 20 μm thick, 1 cm square film made of the composition does not completely dissolve in water at 23° C. for 60 seconds or more. Note that it can be determined that the film is "not completely dissolved" when it can be visually confirmed that the film remains in water. Furthermore, as one embodiment of the present invention, from the viewpoint of suitability for the above-mentioned applications, it is also preferable that the composition of the present invention is not edible.

[0087] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, "parts" and "%" are by mass unless otherwise specified. The obtained polyvinyl alcohol-based resins were analyzed as follows.

[0088] [Content of Ethylene Unit] The content of ethylene units in the ethylene-vinyl alcohol copolymer used in the Examples and Comparative Examples was the same as that of the ethylene-vinyl ester copolymer, which is a precursor or reacetylated product of the ethylene-vinyl alcohol copolymer. １ The ethylene-vinyl ester copolymer was purified by reprecipitation three or more times using a mixed solution of n-hexane and acetone, and then dried under reduced pressure at 80°C for three days to prepare an ethylene-vinyl ester copolymer for analysis. ６ Dissolved in １ H-NMR (500 MHz) was measured. The content of ethylene units was calculated using the peak (4.7 to 5.2 ppm) derived from the main chain methine of the vinyl ester and the peak (0.8 to 1.6 ppm) derived from the main chain methylene of ethylene and vinyl ester.

[0089] [Content of units containing 1,2-diol structure] The content of units containing 1,2-diol structure in the vinyl alcohol copolymer having a 1,2-diol structure in the side chain used in the examples is １ Specifically, the vinyl alcohol copolymer was dissolved in DMSO-d ６ Dissolved in １ H-NMR (500 MHz) was measured. The content of units containing a 1,2-diol structure was calculated using the peak (3.3 ppm) derived from the methylene adjacent to the primary alcohol of the 1,2-diol.

[0090] [Viscosity Average Degree of Polymerization] The viscosity average degree of polymerization of the vinyl alcohol polymer and the ethylene-vinyl alcohol copolymer was determined by the method described in JIS K6726 (1994). Specifically, each polymer or copolymer was resaponified and purified, and then calculated from the intrinsic viscosity [η] (l / g) measured in water at 30°C using the following formula. In the following formula, the degree of polymerization is represented as P. P = ([η] x 10 ４ / 8.29) （１／０．６２）Further, the viscosity average degree of polymerization of the polyvinyl alcohol-based resin (A) was calculated from the degree of polymerization and blending ratio of the vinyl alcohol polymer and / or ethylene-vinyl alcohol copolymer contained in the polyvinyl alcohol-based resin (A).

[0091] [Saponification Degree] The saponification degrees of the vinyl alcohol polymer and ethylene-vinyl alcohol copolymer were determined by the method specified in JIS K6726 (1994).

[0092] [Thickness] The thickness of the laminate and each layer in the laminate in the examples and comparative examples was measured with a digital micrometer.

[0093] <Production Example 1> [Production of Ethylene-Vinyl Alcohol Copolymer (A1)] A continuous polymerization vessel equipped with a reflux condenser, a raw material supply line, a reaction solution discharge line, a thermometer, a nitrogen inlet, an ethylene inlet, and a stirring blade was used. Vinyl acetate was continuously fed to the continuous polymerization vessel at 626 L / hr, methanol at 216 L / hr, and a 1% methanol solution of n-propyl peroxydicarbonate as an initiator at 30.3 L / hr, each using a metering pump. The ethylene pressure in the polymerization vessel was adjusted to 0.69 MPa. The polymerization solution was continuously withdrawn from the continuous polymerization vessel so that the liquid level in the polymerization vessel was constant. The polymerization rate at the outlet of the continuous polymerization vessel was adjusted to 67%. 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 reactor, and while heating to 75°C in a warm water bath, methanol vapor was introduced into the polymerization solution to remove residual vinyl acetate (hereinafter sometimes abbreviated as "VAc"), yielding a methanol solution of an ethylene-vinyl ester copolymer. Next, at 40°C, the water content of the system used in the saponification step was 0.5%, and sodium hydroxide was used as the saponification catalyst in a molar ratio of 0.02 relative to the ethylene-vinyl ester copolymer, for 1 hour, for saponification. The resulting polymer was immersed in methanol and washed. The solvent was then removed by centrifugation, followed by drying, yielding an ethylene-vinyl alcohol copolymer (A1) having an ethylene unit content (sometimes referred to as the Et-modified amount) of 10 mol%, a viscosity-average degree of polymerization (sometimes abbreviated as DP) of 400, and a degree of saponification (sometimes abbreviated as DS) of 98.5 mol%.

[0094] <Production Example 2> [Production of Ethylene-Vinyl Alcohol Copolymer (A2)] A continuous polymerization vessel equipped with a reflux condenser, a raw material supply line, a reaction solution discharge line, a thermometer, a nitrogen inlet, an ethylene inlet, and a stirring blade was used. Vinyl acetate was continuously fed into the continuous polymerization vessel at 631 L / hr, methanol at 165 L / hr, and a 1% methanol solution of n-propyl peroxydicarbonate as an initiator at 3.0 L / hr, each using a metering pump. The ethylene pressure in the polymerization vessel was adjusted to 0.61 MPa. The polymerization vessel was continuously withdrawn from the continuous polymerization vessel so that the liquid level in the polymerization vessel was constant. The conversion at the outlet of the continuous polymerization vessel was adjusted to 38%. 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 vessel was recovered from the continuous polymerization vessel, and the remaining vinyl acetate was removed by introducing methanol vapor into the polymerization vessel while heating it to 75°C in a hot water bath, yielding a methanol solution of an ethylene-vinyl ester copolymer. Next, a saponification reaction was carried out for 1 hour at 40°C using sodium hydroxide as a saponification catalyst in a molar ratio of 0.025 relative to the ethylene-vinyl ester copolymer, with a water content of 0.5% in the system to be subjected to the saponification step. The resulting copolymer was immersed in methanol and washed. The solvent was then removed by centrifugation, and the copolymer was dried to obtain an ethylene-vinyl alcohol copolymer (A2) having an ethylene unit content of 6 mol%, a viscosity-average degree of polymerization of 1000, and a degree of saponification of 99.2 mol%.

[0095] Production Example 3 Production of Vinyl Alcohol Polymer (A3) 1,300 g of vinyl acetate and 500 g of methanol were charged into a separable flask equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen inlet, a feed port for post-addition liquids, and a pump. While stirring, the polymerization solution was purged with nitrogen and heated in a thermostatic bath. Once the temperature reached a constant temperature of 60°C, 0.5 g of 2,2'-azobis(isobutyronitrile) (AIBN) was added to initiate polymerization. 2.3 hours after the start of polymerization, when the conversion reached 30%, 1,000 g of methanol was added to terminate the polymerization. Methanol vapor was blown into the polymerization paste to remove unreacted vinyl acetate monomer, yielding a methanol solution of vinyl ester polymer (sometimes abbreviated as PVAc). Methanol was added to the resulting PVAc solution to adjust the concentration to 25% by mass. To 400 g of this methanol solution (100 g of PVAc in the solution), 11.6 g (molar ratio [MR] relative to vinyl acetate units in the PVAc: 0.025) of an alkaline solution (10% by mass NaOH methanol solution) was added and saponification was carried out at 40°C. After the addition of the alkaline solution, the gel was pulverized in a grinder and the saponification reaction was carried out for a total of 1 hour. Then, 1000 g of methanol was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid vinyl alcohol (PVA) polymer obtained by filtration and the mixture was left to stand at room temperature for 3 hours for washing. The washing procedure was repeated three times, and the resulting PVA polymer was centrifuged and left to stand in a dryer at 70°C for two days to obtain a PVA polymer (A3) having a viscosity-average degree of polymerization of 1,700 and a degree of saponification of 99.2 mol%.

[0096] <Production Example 4> [Production of Modified Vinyl Alcohol Copolymer (A4)] A reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer was charged with 68.0 parts of vinyl acetate, 23.8 parts of methanol, and 8.2 parts of 3,4-diacetoxy-1-butene, and 0.3 mol % (relative to the charged vinyl acetate) of azobisisobutyronitrile was added. The temperature was raised under a nitrogen stream while stirring to initiate polymerization. When the polymerization rate of vinyl acetate reached 90%, m-dinitrobenzene was added to terminate the polymerization. Subsequently, unreacted vinyl acetate monomer was removed from the system by blowing in methanol vapor to give a methanol solution of the copolymer.

[0097] Next, the above methanol solution was further diluted with methanol to a concentration of 45%, and the mixture was charged into a kneader. While maintaining the solution temperature at 35°C, a 2% methanol solution of sodium hydroxide was added at a ratio of 10.5 mmol per mole of the total amount of vinyl acetate units and 3,4-diacetoxy-1-butene units in the copolymer, thereby carrying out saponification. As the saponification proceeded, the saponified product precipitated. When it became particulate, it was filtered out, thoroughly washed with methanol, and dried in a hot air dryer to obtain the desired modified vinyl alcohol copolymer (A4) having 1,2-diol structures in its side chains. The modified vinyl alcohol copolymer (A4) had a viscosity-average degree of polymerization of 450, a degree of saponification of 99.2 mol%, and a content of units containing 1,2-diol structures (sometimes referred to as DO content) of 6%.

[0098] <Production Example 5> [Production of Vinyl Alcohol Polymer (A5)] 630 g of vinyl acetate and 1,170 g of methanol were charged into a separable flask equipped with a stirrer, a nitrogen inlet, and an initiator addition port. The temperature was raised to 60°C, and the system was then purged with nitrogen by nitrogen bubbling for 30 minutes. The internal temperature of the flask was adjusted to 60°C, and 0.5 g of AIBN was added to initiate polymerization. 3.2 hours after the start of polymerization, when the conversion reached 40%, 1,000 g of methanol was added and the mixture was cooled to terminate the polymerization. Unreacted vinyl acetate monomer was removed to obtain a methanol solution of PVAc. Methanol was added to the resulting PVAc solution to adjust the concentration to 25% by mass. 400 g of the methanol solution of PVAc (100 g of PVAc in the solution) was then added with 13.8 g (molar ratio [MR] relative to vinyl acetate units in PVAc: 0.03) of an alkaline solution (10% by mass of NaOH in methanol), and saponification was carried out at 40°C. After the alkali addition, the gel was pulverized in a grinder and subjected to a saponification reaction for a total of 1 hour. Then, 1,000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, 1,000 g of methanol was added to the white solid PVA polymer obtained by filtration and allowed to stand at room temperature for 3 hours for washing. This washing procedure was repeated three times, and the resulting PVA polymer was centrifuged for dewatering. The resulting PVA polymer was then left to dry in a dryer at 70°C for 2 days, yielding PVA polymer (A5) with a viscosity-average degree of polymerization of 500 and a degree of saponification of 98.5 mol%.

[0099] The DP, DS, Et modification amount, and DO content of each of the polymers (A1) to (A5) produced in Production Examples 1 to 5, and the DP of the polyvinyl alcohol resin (A) are shown in Tables 1 and 2.

[0100] [Polyol] The following polyols (B1) having a glass transition temperature (Tg) of 25°C or higher were used. Each Tg was evaluated by DSC measurement under nitrogen at a heating rate of 10°C / min. Furthermore, each crystallization enthalpy (ΔHc) was evaluated by DSC measurement under nitrogen at a heating rate of 10°C / min. Polyol (B1-1): maltitol, Tg = 47°C, ΔHc = 0 J / g (unidentifiable) Polyol (B1-2): trehalose, Tg = 120°C, ΔHc = 0 J / g (unidentifiable) Polyol (B1-3): lactitol, Tg = 33°C, ΔHc = 0 J / g (unidentifiable)

[0101] The following polyols (B2) having a glass transition temperature (Tg) of less than 25°C were used. The Tg of each was evaluated by DSC measurement under nitrogen at a temperature increase rate of 10°C / min. Polyol (B2-1): sorbitol, Tg = -4°C Polyol (B2-2): glycerin, Tg = -75°C

[0102] The following polyols were used as polyol (B3). The crystallization enthalpy (ΔHc) of each was evaluated by DSC measurement under nitrogen at a temperature decrease rate of 10°C / min. Polyol (B3-1): pentaerythritol, ΔHc = 271.5 J / g Polyol (B3-2): dipentaerythritol, ΔHc = 275.4 J / g Polyol (B3-3): mannitol, ΔHc = 219.1 J / g Note that no Tg was observed in the DSC measurement for polyols (B3-1) to (B3-3).

[0103] Example 1 As described below, a composition containing 100 parts by mass of a polyvinyl alcohol-based resin (A) and 67 parts by mass of a polyol (B1) was prepared, and the surface state of the film was evaluated, and the melting point, crystallization temperature, and complex viscosity were measured.

[0104] [Film Surface Condition] 6 g (dry mass) of ethylene-vinyl alcohol copolymer (A1) and 4 g (dry mass) of polyol (B1-1) were dispersed in distilled water to give a dissolution concentration of 20%, and then heated and stirred at a temperature of 95°C for 3 hours to prepare an aqueous solution of the composition. A film having a thickness of approximately 300 μm was then obtained by casting. This film was made of a composition containing 67 parts by mass of polyol (B1) per 100 parts by mass of polyvinyl alcohol resin (A). The surface condition of this film was visually evaluated using the following criteria: ◯: Transparent ×: Polyol bleeds out and becomes white

[0105] [Melting Point, Crystallization Temperature, Complex Viscosity] The melt properties of this film were measured using a dynamic viscoelasticity analyzer (DHR-2, manufactured by TA Instruments). Under nitrogen and at a frequency of 1 Hz, the temperature was lowered from 230°C to 160°C at a rate of 5°C / min. The temperature at which tanδ became 1 or less was taken as the crystallization temperature, and the complex viscosity at 200°C was used as an index of moldability. Next, the temperature was raised from 160°C to 230°C at a rate of 5°C / min. The temperature at which tanδ became greater than 1 was taken as the melting point. Using the above methods, it was confirmed that the melting point of the composition was 202°C, the crystallization temperature was 181°C, and the complex viscosity was 168 Pa s.

[0106] Next, compositions with the same formulation as above were prepared as follows, and their physical properties were evaluated. Note that, since the compositions prepared by each method below all had the same composition, the melting point of the composition was 202°C, the crystallization temperature was 181°C, and the complex viscosity was 168 Pa s.

[0107] [Oxygen Barrier Property] 6 g (in terms of dry mass) of ethylene-vinyl alcohol copolymer (A1) and 4 g (in terms of dry mass) of polyol (B1-1) were dispersed in distilled water so that the dissolved concentration was 20%, and then the dispersion was heated and stirred at a temperature of 95°C for 3 hours to prepare an aqueous solution of the composition. Next, a double-bleached kraft paper (100 μm thick, 70 g / m ２ The composition was dried in a hot air dryer at 80°C for 30 minutes to obtain a barrier paper with a 20 µm thick film of the composition. The oxygen transmission rate (OTR) (unit: cc / m) of the barrier paper (laminate of paper and composition) was ２The oxygen permeability (per day atm) of the barrier paper was measured after conditioning the barrier paper for 7 days at a temperature of 23°C and a relative humidity of 65%. The thickness of the composition layer in the barrier paper (laminate of paper and composition) obtained in Examples 2 to 14 was 10 to 36 μm, and the oxygen permeability shown in Tables 1 and 2 is the value converted into a thickness of the composition layer in the barrier paper of 20 μm. The oxygen barrier property was evaluated using the following index: ◯: OTR<1.5 cc / m ２ ・day・atm △: 1.5cc / m ２ ・day・atm≦OTR<3.0cc / m ２ ・day・atm ×: 3.0cc / m ２ ・day・atm≦OTR

[0108] [Melt moldability] Compression molding and extrusion molding were carried out as follows to evaluate the melt moldability of the composition. (Compression molding) 120 g of ethylene-vinyl alcohol copolymer (A1) in dry mass and 80 g of polyol (B1-1) in dry mass were dry blended and then charged into a twin-screw extruder (ULT-Nano, manufactured by Technovel Co., Ltd.). The twin-screw extruder was melt-kneaded at a screw rotation speed of 50 rpm and a cylinder temperature of 220°C to obtain pellets of the composition. Next, the obtained pellets of the composition were each compressed using a compression molding machine under a load of 50 kgf / cm. ２ The pellets were compression molded for 5 minutes under the above conditions to obtain a melt-molded product. Molding was performed at a mold temperature of 200°C, and if the pellets did not melt, the temperature was increased in 10°C intervals, and the temperature at which the pellets melted and a sheet was obtained was measured, and the melt moldability by compression molding was evaluated using the following index: ◯: Sheeting possible at a molding temperature of 200°C △: Sheeting possible at a molding temperature of 210°C ×: Sheeting possible at a molding temperature of 220°C or 230°C

[0109] (Extrusion Molding) A laminate comprising a layer containing a composition and a layer containing a biodegradable polyester was prepared by the following method, and its melt moldability by extrusion molding was evaluated. Pellets of the composition and pellets of polylactic acid (Ingeo (registered trademark) biopolymer 2003D, Natureworks), a biodegradable polyester, were each charged into the hopper of a single-screw extruder (VGM25-28EX, manufactured by G.M. ENGINEERING) and co-extruded using a feed block die at a cylinder temperature of 210°C, a die temperature of 200°C, and a flow rate of 5 kg / h to obtain a two-kind, three-layer laminate with a width of 20 cm and a thickness of 500 μm. The resulting laminate had a structure of polylactic acid layer / composition layer / polylactic acid layer = 200 μm / 100 μm / 200 μm (thickness) from the outside. The melt moldability by extrusion molding (co-extrusion molding) was evaluated using the following indicators. ◯: A laminate can be obtained. △: A laminate can be obtained by increasing the cylinder temperature to 220°C. ×: Extrusion is not possible even at a cylinder temperature of 220°C, or there is significant film thickness unevenness.

[0110] The laminate obtained above was biodegradable.

[0111] Examples 2 to 14, Comparative Examples 1 to 10 Compositions were prepared and evaluated in the same manner as in Example 1 using the formulations shown in Tables 1 and 2. The results are shown in Tables 1 and 2. All of the laminates obtained in Examples 2 to 14 were biodegradable.

[0112] The compositions of Examples 1 to 14 were confirmed to have excellent melt moldability and oxygen barrier properties because they contained a specific amount of polyol (B1) having a glass transition temperature of 25°C or higher and had melting points and crystallization temperatures within specific ranges. On the other hand, the composition of Comparative Example 1 did not contain polyol (B1), and the compositions of Comparative Examples 2 and 7 did not contain polyol (B1) and in addition had melting points exceeding 210°C and crystallization temperatures exceeding 190°C, so were poor in oxygen barrier properties and / or melt moldability. The compositions of Comparative Examples 3 and 5 had melting points exceeding 210°C and crystallinity degrees exceeding 190°C, so were poor in melt moldability. The composition of Comparative Example 4 had a polyol (B1) content of more than 130 parts by mass, so were poor in oxygen barrier properties and melt moldability. The composition of Comparative Example 6 had a polyol (B1) content of less than 26 parts by mass, so were poor in melt moldability. The compositions of Comparative Examples 8 to 10 did not contain polyol (B1) and contained polyol (B3) with a crystallization enthalpy of greater than 100 J / g, so bleed-out occurred, whitening occurred, and the surface condition was poor. Therefore, other evaluations could not be performed.

Claims

1. A composition comprising a polyvinyl alcohol-based resin (A) and a polyol (B1), The glass transition temperature of polyol (B1) is 25°C or higher. The polyol (B1) content is 26 parts by mass or more and 130 parts by mass or less per 100 parts by mass of polyvinyl alcohol resin (A). A composition having a melting point of 210°C or lower and a crystallization temperature of 190°C or lower.

2. The composition according to claim 1, wherein the crystallization enthalpy of the polyol (B1) obtained by differential scanning calorimetry at a cooling rate of 10°C / min is 100 J / g or less.

3. The composition according to claim 1, wherein the polyol (B1) is at least one polyol selected from the group consisting of maltitol, lactitol, and trehalose.

4. The composition according to claim 1, further comprising a polyol (B2) having a glass transition temperature of less than 25°C.

5. The composition according to claim 4, wherein the content of polyol (B2) is 20 parts by mass or less per 100 parts by mass of polyvinyl alcohol resin (A).

6. The composition according to claim 1, which does not contain polyol (B2) having a glass transition temperature of less than 25°C.

7. The composition according to claim 1, further comprising starch, wherein the starch content is 40% by mass or less relative to the mass of the composition.

8. The composition according to claim 1, which does not contain starch.

9. The composition according to claim 1, wherein the polyvinyl alcohol-based resin (A) comprises a vinyl alcohol-based polymer having a degree of saponification of 90 mol% or more and 99.99 mol% or less.

10. The composition according to claim 1, wherein the viscosity-average degree of polymerization of the polyvinyl alcohol-based resin (A) is 200 or more and 1500 or less.

11. The composition according to claim 1, wherein the polyvinyl alcohol-based resin (A) comprises an α-olefin-vinyl alcohol copolymer.

12. The composition according to claim 11, wherein the α-olefin-vinyl alcohol copolymer contains structural units derived from an α-olefin having 4 or fewer carbon atoms.

13. The composition according to claim 1, wherein the polyvinyl alcohol resin (A) contains an ethylene-vinyl alcohol copolymer, and the ethylene unit content of the ethylene-vinyl alcohol copolymer is 1 mol% or more and 12 mol% or less.

14. The composition according to claim 13, wherein the content of the ethylene-vinyl alcohol copolymer is 50% by mass or more relative to the mass of the polyvinyl alcohol resin (A).

15. The oxygen permeability (OTR) is 3.0 cc / m³. ２ The composition according to claim 1, wherein the concentration is less than or equal to day ATM.

16. A molten article comprising the composition described in any one of claims 1 to 15.

17. A laminate comprising a layer containing the composition according to any one of claims 1 to 15.

18. The laminate according to claim 17, wherein the laminate further comprises a layer containing biodegradable polyester.

19. The laminate according to claim 18, wherein the biodegradable polyester is at least one biodegradable polyester selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and polyhydroxyalkanoate.

20. Food packaging comprising the laminate described in claim 17.