Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
  • C08K5/098—Metal salts of carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/02—Homopolymers or copolymers of unsaturated alcohols
  • C08L29/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
  • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Definitions

• the present invention relates to a resin composition that contains a polyvinyl alcohol-based resin and has excellent thermal stability and molding stability during melt molding, a film or sheet made of the resin composition, and a multilayer structure that contains a layer made of the resin composition.
• Containers and packaging films are used in a wide range of fields, including agriculture, civil engineering, industry, medical, packaging, leisure, toys, miscellaneous goods, daily necessities, containers, and parts, and require gas barrier properties to prevent deterioration of the content.
• Polyvinyl alcohol (PVA) has high crystallinity due to hydrogen bonds between hydroxyl groups, and due to this high crystallinity, it has excellent gas barrier properties. Therefore, PVA-based resins or resin compositions thereof are used as gas barrier layers for the above-mentioned containers and packaging films.
• molded products such as containers and films are produced by melt molding from the viewpoint of productivity.
• PVA polyvinyl alcohol
• modified PVA-based resins that can be melt molded have also been proposed (for example, PVA-based resins having a 1,2-diol structure in the side chain described in Patent Documents 1, 2, 3, etc.).
• molded products of PVA-based resins are hard, it is known to add a plasticizer to PVA-based resin compositions for melt molding, such as packaging films and containers (for example, Patent Document 4).
• the present invention was made in consideration of these circumstances, and its purpose is to provide a resin composition that contains a PVA-based resin and has excellent thermal stability and molding stability during melt molding.
• the inventors discovered that by incorporating an appropriate amount of formic acid and acetate groups into a PVA-based resin to create a resin composition, the thermal stability and molding stability during melt molding are improved compared to the case of using PVA-based resin alone, and thus completed the present invention.
• the gist of the present invention is as follows:
• Aspect 1 of the present invention is a resin composition containing a polyvinyl alcohol resin, a formic acid group, and an acetate group, characterized in that the content of the formic acid group in the resin composition is 4 to 500 ppm, and the content ratio of the formic acid group to the acetate group (formic acid group/acetate group) is 0.001 to 0.200.
• the resin composition of aspect 2 of the present invention is characterized in that in aspect 1, the content of the acetate group in the resin composition is 10,000 ppm or less.
• the resin composition of aspect 3 of the present invention is characterized in that in aspect 1 or 2, the polyvinyl alcohol resin contains a structural unit having a modifying group other than ethylene.
• the resin composition of aspect 4 of the present invention is characterized in that in any one of aspects 1 to 3, the polyvinyl alcohol resin contains a structural unit having a hydrophilic modifying group.
• the resin composition of aspect 5 of the present invention is characterized in that in any one of aspects 1 to 4, the polyvinyl alcohol resin contains a structural unit having a primary hydroxyl group in the side chain.
• the resin composition of aspect 6 of the present invention is any one of aspects 1 to 5, characterized in that the content of formic acid groups is 5 to 100 ppm.
• Aspect 7 of the present invention is a molded article containing the resin composition of any one of aspects 1 to 6.
• Aspect 8 of the present invention is a film containing the resin composition described in any one of aspects 1 to 6.
• Aspect 9 of the present invention is a sheet containing the resin composition described in any one of aspects 1 to 6.
• Aspect 10 of the present invention is a multilayer structure containing at least one layer made of the resin composition described in any one of aspects 1 to 6.
• the resin composition of the present invention contains a PVA-based resin and has excellent thermal stability and molding stability when subjected to melt molding.
• the resin composition of the present invention is a resin composition containing a polyvinyl alcohol-based resin (PVA-based resin), a formic acid group, and an acetate group, in which the content of the formic acid group in the resin composition is 4 to 500 ppm, and the content ratio of the formic acid group to the acetate group (formic acid group/acetate group) is 0.001 to 0.200.
• PVA-based resin polyvinyl alcohol-based resin
• a formic acid group formic acid group
• an acetate group in which the content of the formic acid group in the resin composition is 4 to 500 ppm, and the content ratio of the formic acid group to the acetate group (formic acid group/acetate group) is 0.001 to 0.200.
• the PVA-based resin used in the resin composition of the present invention is a PVA-based resin that is subjected to molding, including film formation, by a solution casting method.
• the PVA-based resin may also include a copolymer-modified PVA-based resin obtained by saponifying a copolymer obtained by copolymerizing a modifying monomer in order to impart a desired property (e.g., water resistance) to the PVA-based resin, or a post-modified PVA-based resin obtained by post-modifying a PVA-based resin.
• PVA-based resin is a general term for unmodified PVA, copolymer-modified PVA, and post-modified PVA.
• modified PVA-based resin When copolymer-modified PVA and post-modified PVA are collectively referred to, they are called "modified PVA-based resin.”
• Unmodified PVA-based resin is a polyvinyl alcohol obtained by saponifying polyvinyl ester obtained by polymerizing vinyl ester-based monomers, and contains vinyl alcohol units represented by the following formula (1) and vinyl ester units (the following formula (2)) which are unsaponified portions. The vinyl ester units are included when the saponification degree is less than 100%.
• vinyl ester monomers examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, and vinyl versatate, with vinyl acetate being economically preferred.
• R a depends on the type of vinyl ester monomer used, and when vinyl acetate monomer is used, it is a methyl group.
• the number-average degree of polymerization of unmodified PVA-based resins is usually 150 to 4000, preferably 200 to 2000, more preferably 250 to 800, and even more preferably 300 to 600. If the average degree of polymerization is too low, it tends to be difficult to form a stable shape during melt molding, and if it is too high, the viscosity of the resin composition tends to become too high, making molding difficult.
• the viscosity of an aqueous solution may be used as an index of the average degree of polymerization of unmodified PVA-based resin.
• the viscosity of a 4% by weight aqueous solution at 20°C, measured in accordance with JIS K6726:1994, is usually 1.5 to 20 mPa ⁇ s, preferably 2 to 12 mPa ⁇ s, and particularly preferably 2.5 to 8 mPa ⁇ s. If the viscosity is too low, it tends to be difficult to form a stable shape during melt molding, and if it is too high, molding tends to be difficult.
• the degree of saponification of the unmodified PVA-based resin is usually 70 to 99.9 mol%, preferably 75 to 99.7 mol%, and particularly preferably 78 to 99.5 mol%. If the degree of saponification is too low, the flexibility becomes too high, and the shape stability during lamination tends to decrease.
• the degree of saponification was measured in accordance with JIS K6726:1994.
• the melting point of unmodified PVA resins varies depending on the degree of polymerization and saponification, but is preferably around 200 to 250°C, and the decomposition temperature is preferably around 250 to 300°C.
• the main chain bond is mainly 1,3-diol bonds, and the content of 1,2-diol bonds is about 1.5 to 1.7 mol %, but the content of 1,2-diol bonds can be increased by raising the polymerization temperature when polymerizing vinyl ester-based monomers.
• Modified PVA-based resin Copolymer modified PVA-based resins are obtained by saponifying a copolymer obtained by copolymerizing a modifying monomer.
• copolymerization monomers (modifying monomers) used in the copolymerized modified PVA-based resin include olefins such as ethylene, propylene, isobutylene, ⁇ -octene, ⁇ -dodecene, and ⁇ -octadecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid, or their salts or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid
• polyoxyalkylene (meth)allyl ether examples include polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate; polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (meth)acrylamide; hydroxyl group-containing ⁇ -olefins such as polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, 3-buten-1-ol, 4-penten-1-ol, and 5-hexen-1-ol, and derivatives thereof such as acylated products.
• polyoxyalkylene (meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate
• the post-modified PVA-based resin can be obtained by post-modifying a PVA-based resin.
• post-modified PVA-based resins include those having an acetoacetyl group by reaction with diketene, those having a polyalkylene oxide group by reaction with ethylene oxide, those having a hydroxyalkyl group by reaction with an epoxy compound or the like, and those obtained by reacting an aldehyde compound having various functional groups with a PVA-based resin.
• modified PVA-based resins that is, the content of structural units derived from various monomers in the copolymer or functional groups introduced by post-reaction, cannot be generalized because the characteristics vary greatly depending on the type of modification, but is usually 0.1 to 20 mol%, and a range of 0.5 to 15 mol% is particularly preferable.
• a PVA-based resin containing a structural unit having a hydrophilic modified group is preferably used.
• hydrophilic modified groups include a hydroxyl group, a carboxyl group, and an amino group.
• a PVA-based resin containing a structural unit having a primary hydroxyl group in the side chain is preferred.
• a PVA-based resin containing a structural unit having a 1,2-diol modified group is preferred.
• the modified PVA resin containing a structural unit having a 1,2 diol modifying group contains a structural unit having a 1,2 diol modifying group in the side chain in addition to the vinyl alcohol unit represented by the following formula (1) that constitutes polyvinyl alcohol, and the vinyl ester unit (the following formula (2)) that is the unsaponified portion.
• the vinyl ester unit is included when the degree of saponification is less than 100%.
• R a depends on the type of vinyl ester monomer used, and for example, when vinyl acetate monomer is used, it is a methyl group.
• a side chain 1,2-diol-containing unit represented by the following formula (3) is preferred.
• R 1 to R 6 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X represents a single bond or a bonding chain.
• R 1 to R 6 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or a tert-butyl group, which may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group).
• a hydrogen atom is more preferable.
• R 1 to R 6 may be the same or different, but preferably all are hydrogen atoms. When all are hydrogen atoms, the terminals of the side chains become primary hydroxyl groups, which is preferable in that the reactivity with adhesive resins such as acid-modified polyolefin resins is improved and the formation of a laminate is facilitated.
• X is a single bond or a bonding chain.
• the bonding chain (X) include hydrocarbon groups such as alkylene groups, alkenylene groups, alkynylene groups, phenylene groups and naphthylene groups (these hydrocarbon groups may be substituted with halogen atoms such as fluorine atoms, chlorine atoms and bromine atoms), -O-, -(CH 2 O) m -, -(OCH 2 ) m -, -(CH 2 O) m CH 2 -, -CO-, -COCO-, -CO(CH 2 ) m CO-, -CO(C 6 H 4 )CO-, -S-, -CS-, -SO-, -SO 2 -, -NR-, -CONR-, -NRCO-, -CSNR-, -NRCS-, -NRNR-, -HPO 4 -, -Si(OR) 2 -
• X is preferably a single bond, an alkylene group having 6 or less carbon atoms (particularly a methylene group), or —CH 2 OCH 2 —, and among these, a single bond is most preferable from the viewpoint of thermal stability and stability under high temperatures or acidic conditions.
• a structural unit having a primary hydroxyl group in a side chain in which R5 and R6 are hydrogen atoms is particularly preferred, and the most preferred structural unit is a structural unit represented by the following formula (3a) in which R1 to R6 are all hydrogen atoms and X is a single bond.
• the degree of modification (content) of the modified PVA resin is preferably 0.1 to 20 mol%, more preferably 0.5 to 15 mol%, even more preferably 1 to 10 mol%, and particularly preferably 2 to 8 mol%. If the modification rate is too low, the reactivity with adhesive resins such as acid-modified polyolefin resins tends to decrease, and if it is too high, the crystallization rate becomes too slow, and when a laminate is formed with other resins, the laminate tends to deform, and the appearance tends to deteriorate.
• the number-average degree of polymerization of the modified PVA-based resin is preferably 150 to 4000, more preferably 200 to 2000, even more preferably 250 to 800, and particularly preferably 300 to 600. If the average degree of polymerization is too low, it tends to be difficult to form a stable shape during melt molding, and if it is too high, the viscosity of the resin composition tends to become too high, making molding difficult.
• the viscosity of a 4% by weight aqueous solution of the modified PVA resin at 20°C, measured in accordance with JIS K6726:1994, is preferably 1.5 to 20 mPa ⁇ s, more preferably 2 to 12 mPa ⁇ s, and particularly preferably 2.5 to 8 mPa ⁇ s. If the viscosity is too low, it tends to be difficult to form a stable shape during melt molding, and if it is too high, molding tends to be difficult.
• the degree of saponification of the modified PVA resin (average degree of saponification measured in accordance with JIS K6726:1994) is preferably 70 to 100 mol%, more preferably 80 to 99.9 mol%, and particularly preferably 85 to 99.7 mol%. If the degree of saponification is too low, the gas barrier properties tend to decrease.
• the melting point of the modified PVA resin depends on the degree of polymerization and saponification, but it is preferable that the melting point is 160 to 230°C, and the decomposition temperature is 250 to 350°C.
• the PVA-based resin that can be used in the resin composition of the present invention may be one type or a mixture of two or more types.
• examples of the mixture include combinations of the above-mentioned unmodified PVA-based resins, unmodified PVA-based resins and various modified PVA-based resins, and different types of modified PVA-based resins.
• examples of the mixture include combinations of modified PVA-based resins of the same type but with different saponification degrees, polymerization degrees, modification rates, etc.
• the PVA-based resin is preferably contained in the resin composition in an amount of 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.
• Formic acid is a carboxylic acid that has a formyl group in addition to the carboxy group.
• the thermal stability and molding stability of the PVA-based resin can be improved by adjusting the ratio of the acid and base contained therein.
• acetic acid and/or an acetate salt are used as the acid.
• the present inventors have found that the thermal stability and molding stability of the PVA-based resin during melt molding can be improved by using formic acid and/or a formate salt as the acid in addition to the above. The reason for this is unclear, but it is presumed that because formic acid and formate salts have reducing properties, the oxidative decomposition of the PVA-based resin is suppressed compared to when only acetic acid or acetate salts are used.
• acetic acid and acetate ion are collectively referred to as "acetate radical”
• formic acid and formate ion are collectively referred to as "formate radical”.
• Formic acid can generally be produced by (i) reacting methanol with carbon monoxide under strongly basic conditions to produce methyl formate, which is then hydrolyzed; (ii) reacting methyl formate with ammonia to produce formaldehyde, which is then hydrolyzed with sulfuric acid; or (iii) reacting sodium hydroxide with carbon monoxide to produce sodium formate, which is then neutralized with hydrochloric acid.
• Formate ions can be added using a formate salt.
• formate salts include sodium formate, potassium formate, lithium formate, magnesium formate, calcium formate, barium formate, zinc formate, copper formate, iron formate, nickel formate, manganese formate, lead formate, tin formate, chromium formate, and ammonium formate, with sodium formate being preferred.
• sodium formate such as sodium formate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.
• the content of formic acid radicals in the resin composition of the present invention (per the mass of the entire resin composition) is 4 to 500 ppm, preferably, for example, 4 to 450 ppm, and more preferably, for example, 5 to 100 ppm.
• the content of formic acid radicals is preferably 4.3 ppm or more, more preferably 4.5 ppm or more, even more preferably 4.8 ppm or more, even more preferably 5 ppm or more, particularly preferably 10 ppm or more, and particularly preferably 15 ppm or more.
• the content of formic acid radicals is preferably 450 ppm or less, more preferably 400 ppm or less, even more preferably 300 ppm or less, even more preferably 200 ppm or less, particularly preferably 150 ppm or less, and particularly preferably 100 ppm or less.
• the numerical range of the content of formic acid radicals can be set by any combination of the above-mentioned lower and upper limits and the numerical values described in the Examples column. The same applies to the numerical ranges other than the content of formic acid radical.
• the above-mentioned content (4 to 500 ppm) is necessary.
• the formic acid group content is 4 ppm or more, the thermal stability is good.
• the formic acid group content is 500 ppm or less, the molding stability during melt molding is good.
• the content of formic acid groups in the resin composition can be measured by the method described in the Examples section.
• the resin composition of the present invention may contain only formic acid as the formic acid radical, may contain only formic acid ions, or may contain both formic acid and formic acid ions.
• the resin composition of the present invention further contains an acetate group (acetic acid, acetate ion).
• Acetic acid is a type of carboxylic acid that has a linear saturated hydrocarbon chain.
• Acetic acid can be synthesized by carbonylation of methanol, and examples of commercially available products include acetic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.
• Acetate ions can be added using acetate salts.
• the acetate salt is not limited to any particular salt, and sodium acetate is preferably used.
• Commercially available sodium acetate includes, for example, sodium acetate manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.
• the content of acetate groups in the resin composition of the present invention is preferably 1000 ppm or more, more preferably 1500 ppm or more, even more preferably 1800 ppm or more, and particularly preferably 2000 ppm or more, from the viewpoint of molding stability during melt molding.
• the content of acetate groups is preferably 10000 ppm or less, more preferably 9500 ppm or less, even more preferably 9000 ppm or less, and particularly preferably 8500 ppm or less, from the viewpoint of thermal stability.
• the content of acetate groups is, for example, 10000 ppm or less, and preferably 1000 to 10000 ppm.
• the acetate group may be contained not only as an impurity generated during the production process of the PVA-based resin, but also by being added separately.
• the content of acetate groups in the resin composition can be measured by the method described in the Examples section.
• the content ratio of formic acid groups to acetic acid groups is 0.001 or more, preferably 0.0015 or more, more preferably 0.0018 or more, and particularly preferably 0.002 or more, from the viewpoint of thermal stability and molding stability.
• the content ratio of formic acid groups to acetic acid groups is 0.200 or less, more preferably 0.100 or less, and particularly preferably 0.050 or less, from the viewpoint of thermal stability. In other words, the content ratio of formic acid groups to acetic acid groups (formic acid groups/acetic acid groups) is 0.001 to 0.200.
• the content ratio of formic acid groups to acetic acid groups (formic acid groups/acetic acid groups) is based on mass.
• the resin composition of the present invention may contain only acetic acid as the acetate radical, may contain only acetate ions, or may contain both acetic acid and acetate ions.
• the resin composition of the present invention may contain other plasticizers within a range that does not impair the effects of the present invention (water solubility, gas barrier properties).
• the resin composition of the present invention may contain other polymers (resins) within a range that does not impair the effects of the present invention (for example, less than 30% by mass of the resin composition).
• examples of the polymers (resins) that may be contained include various thermoplastic resins such as polyamide, polyester, polyethylene, polypropylene, and polystyrene.
• the resin composition of the present invention may contain, as necessary, a reinforcing agent, a filler, a pigment, a dye, a lubricant, an antioxidant, an antistatic agent, an ultraviolet absorber, a heat stabilizer, a light stabilizer, a surfactant, an antibacterial agent, an antistatic agent, a drying agent, an antiblocking agent, a flame retardant, a crosslinking agent, a curing agent, a foaming agent, a crystal nucleating agent, and the like, within a range that does not impair the effects of the present invention (for example, 10% by mass or less of the resin composition).
• the resin composition of the present invention having the above composition has good thermal stability and molding stability due to the coexistence of formic acid groups and acetic acid groups, without impairing the properties of the PVA-based resin.
• the resin composition having the above-mentioned composition can be prepared by (i) dry blending a PVA-based resin with formic acid and/or a formate, acetic acid and/or an acetate, and other components, followed by melt kneading, or (ii) mixing an aqueous solution of a PVA-based resin, formic acid and/or a formate, acetic acid and/or an acetate, and other components.
• the method (i) is preferred, as it allows the resin composition to be obtained in the form of pellets.
• acetate radicals may be contained as impurities generated during the production process of the PVA-based resin. In this case, it is not necessary to add acetic acid and/or acetate salts in the above methods (i) and (ii).
• acetic acid and/or an acetate salt When acetic acid and/or an acetate salt is added, the order of addition of formic acid and/or a formate salt and acetic acid and/or an acetate salt does not matter, and they may be premixed and added to the PVA-based resin, or formic acid and/or a formate salt may be added to a premix of the PVA-based resin and acetic acid and/or an acetate salt.
• the resin composition of the present invention is melt moldable, and a melt extrusion molding method generally used for thermoplastic resins can be employed. Therefore, the resin composition of the present invention can be suitably used for producing various molded articles, for example, melt molded articles that require gas barrier properties, particularly melt molded films, stretched films, bags made of sheets, and containers and lids made of cups, trays, tubes, bottles, etc.
• the film, sheet or container may be a film, sheet or container made of the resin composition of the present invention alone (single layer), or may be used as a multilayer structure having two or more layers of other thermoplastic resins, papers, etc. In such a multilayer structure, there may be at least one layer made of the resin composition of the present invention (resin composition layer).
• Multilayer structure containing the resin composition layer of the present invention include, for example, food packaging materials such as coffee capsules and shrink films, pharmaceutical packaging materials, cosmetic packaging materials such as lotion and foundation cases, packaging materials for metal parts, packaging materials for electronic parts, packaging materials for items that need to be protected from deterioration of properties due to oxidation or moisture absorption, packaging materials for substances where odor transfer or leakage is a concern, and multilayer structures used in various agricultural sheets and agricultural materials such as mulch sheets, fumigation sheets, seedling trays, and covering sheets.
• food packaging materials such as coffee capsules and shrink films
• pharmaceutical packaging materials such as lotion and foundation cases
• packaging materials for metal parts packaging materials for electronic parts
• packaging materials for items that need to be protected from deterioration of properties due to oxidation or moisture absorption packaging materials for substances where odor transfer or leakage is a concern
• multilayer structures used in various agricultural sheets and agricultural materials such as mulch sheets, fumigation sheets, seedling trays, and covering sheets.
• Applicable melt molding methods include injection molding and extrusion molding.
• Extrusion molding is particularly suitable as a molding method for films or sheets, and examples include the T-die molding method and the inflation molding method (tubular film method). Not only single-layer extrusion but also multi-layer extrusion is possible.
• Multi-layer extrusion co-extrusion molding is suitable for manufacturing multi-layer structures in which films are laminated.
• the obtained film or sheet may be subjected to secondary processing such as uniaxial or biaxial stretching. Since the resin composition of the present invention has excellent stretchability, it is preferable to perform a stretching process to improve the strength of the film and further improve the gas barrier properties.
• sample freeze-pulverized pellets
• 5 ml of 1% p-toluenesulfonic acid-ethanol solution was added using a whole pipette, and the vial was sealed with a hand clipper (only 5 ml of 1% p-toluenesulfonic acid-ethanol solution was used for the blank).
• the vial was set in an ultrasonic cleaner set at 60°C and operated for 2 hours to perform ethyl esterification of formic acid.
• the vial was removed from the ultrasonic cleaner and allowed to stand at room temperature for 3 hours or more.
• 0.5 g of formic acid was precisely weighed into a measuring flask and the volume was adjusted to 50 ml with ethanol (10,000 mg/L solution).
• the solution was appropriately diluted stepwise to prepare a standard solution, and 0.5 g of the standard solution was precisely weighed into a 20 ml vial, 5 ml of 1% p-toluenesulfonic acid-ethanol solution was added using a whole pipette, and the vial was sealed with a hand clipper. Headspace analysis was carried out under the conditions shown in Table 1 below.
• GC gas chromatography
• MS mass spectrometry
• the acetate radical content was measured by the following pH measurement and neutralization titration method.
• Thermal Stability was evaluated by the following TGA constant temperature method. 5 mg of the resin composition pellets were heated using a thermogravimetric analyzer (Pyris 1 TGA, manufactured by Perkin Elmer) under conditions of a nitrogen atmosphere: 20 mL/min, a temperature: 230°C, and a heating time: 1 hour, and the weight after heating was measured to measure the residual rate. When the residual rate was 90% or more, the thermal stability was evaluated as good. When the residual rate was less than 90%, the thermal stability was evaluated as poor.
• the dynamic viscosity behavior was evaluated by the following method. 55 g of the resin composition pellets were kneaded for 30 minutes under the conditions of 230°C and 50 rpm in a Plastograph (manufactured by Brabender). The torque values were measured at 5 minutes and 20 minutes, and the torque ratio (Torque (20 minutes)/Torque (5 minutes)) was used for evaluation. The larger this value, the more the viscosity of the PVA-based resin composition increased. In melt molding, it is preferable to show dynamic viscosity behavior with small viscosity change.
• the resin composition of Comparative Example 1 which contains a large amount of formic acid groups and has a large formic acid group/acetic acid group ratio
• the resin compositions of Comparative Examples 2 and 3 which have a small formic acid group/acetic acid group ratio
• have a low residual rate in the TGA constant temperature method evaluation indicating that they have poor thermal stability
• the resin composition of Comparative Example 4 which contains a small amount of formic acid groups, has a large viscosity change in the dynamic viscosity behavior evaluation, indicating that it has poor molding stability.
• the PVA-based resin used was an unmodified PVA-based resin having a degree of saponification of 87.6 mol % as measured in accordance with JIS K6726 and a number average degree of polymerization of 500 as measured in accordance with JIS K6726.
• Each resin composition pellet according to Examples 7 to 8 and Comparative Examples 5 to 6 was prepared in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 4, except that the unmodified PVA-based resin, formic acid, sodium formate, acetic acid, and sodium acetate were mixed in the ratios shown in Table 3.
• the resin composition pellets prepared based on the above-mentioned measurement and evaluation method were subjected to evaluation of thermal stability by a constant temperature TGA method and molding stability by dynamic viscosity behavior. The results are shown in Table 3.
• the resin composition of the present invention contains a PVA-based resin and has sufficient thermal stability and molding stability during melt molding, making it suitable for use in various packaging materials, particularly food packaging materials such as coffee capsules.

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• 2024
  • 2024-03-27 CN CN202480023646.3A patent/CN120981522A/zh active Pending
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• 2025
  • 2025-09-26 US US19/341,440 patent/US20260022230A1/en active Pending

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