Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/0013—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fillers dispersed in the moulding material, e.g. metal particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
  • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/346—Clay
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L101/00—Compositions of unspecified macromolecular compounds
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C2045/0091—Pellets or granules, e.g. their structure, composition, length, height, width
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
  • B29C2945/76—Measuring, controlling or regulating
  • B29C2945/76003—Measured parameter
  • B29C2945/761—Dimensions, e.g. thickness
  • B29C2945/76103—Dimensions, e.g. thickness shrinkage, dilation, dimensional change, warpage
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
  • B29K2029/04—PVOH, i.e. polyvinyl alcohol

Definitions

• the present invention relates to polyvinyl alcohol-based resin compositions and injection molded articles.
• Vinyl alcohol-based resins such as polyvinyl alcohol-based resins (hereinafter also referred to as PVA-based resins) are excellent in solvent resistance, gas barrier properties, strength, transparency, etc., so they are used in various molded products such as food packaging containers. It is
• melt molding examples include melt molding.
• melt-molding methods include injection molding, extrusion molding such as T-die and inflation, compression molding, blow molding, vacuum molding, and press molding.
• Patent Document 1 contains a PVA-based resin (A) and a multimeric aldehyde compound (B), and the content of the multimeric aldehyde compound (B) is 100 mass of the PVA-based resin (A).
• a resin composition is described that is 0.5 ⁇ 10 ⁇ 4 to 100 ⁇ 10 ⁇ 4 parts by weight per part. It also describes that raw material pellets using such a resin composition can be melt-molded by an extrusion molding method or an injection molding method.
• an object of the present invention is to provide a PVA-based resin composition that allows an injection-molded article to be easily removed from a mold during injection molding and has excellent releasability.
• the molding shrinkage ratio in at least one of the MD (machine direction) direction and the TD (transverse direction) direction during injection molding of the PVA-based resin composition is a specific value or more, The present inventors have found that it is possible to suppress excessive adhesion between the PVA-based resin composition and the mold and improve releasability, thereby completing the present invention.
• Alcohol-based resin composition 2.
• the polyvinyl alcohol-based resin composition further contains a mold shrinkage rate modifier (B), 3.
• the PVA-based resin composition of the present invention it is possible to provide a PVA-based resin composition that is easily removed from the mold during injection molding and has excellent releasability because the molding shrinkage ratio is adjusted to a specific range.
• the polyvinyl alcohol-based resin composition (PVA-based resin composition) is a PVA-based resin composition containing polyvinyl alcohol-based resin (A) (PVA-based resin (A)).
• the molding shrinkage in at least one of the MD direction and the TD direction is 0.4% or more. Adhesion between the PVA-based resin composition and the mold is suppressed by setting the molding shrinkage rate in at least one of the MD direction and the TD direction during injection molding of the PVA-based resin composition to 0.4% or more. This makes it easier for the injection-molded product to come off from the mold, improving mold releasability.
• Such molding shrinkage is preferably 0.45% or more, more preferably 0.5% or more.
• the molding shrinkage rate is preferably 1.0% or less, more preferably 0.9% or less, and even more preferably 0.8% or less. That is, the molding shrinkage rate in at least one of the MD direction and the TD direction during injection molding is 0.4% or more and 1.0% or less, so that the shape of the injection molded product is not impaired and the mold It is preferable because it becomes easier to come off.
• the molding shrinkage ratio in at least one of the MD direction and the TD direction during injection molding is preferably within the above range, and the MD direction and the TD direction during injection molding. It is more preferable that the molding shrinkage ratios of both are within the above ranges.
• the molding shrinkage rate in the MD direction during injection molding is preferably 0.4% or more, more preferably 0.45% or more, and more preferably 0.5% or more, from the viewpoint of improving the releasability of the injection molded product. More preferred.
• the molding shrinkage rate in the MD direction during injection molding is preferably 1.0% or less, more preferably 0.9% or less, and further preferably 0.8% or less, from the viewpoint of not damaging the shape of the injection molded product. preferable.
• the molding shrinkage rate in the TD direction during injection molding is preferably 0.4% or more, more preferably 0.45% or more, and even more preferably 0.5% or more, from the viewpoint of improving the releasability of the injection molded product. .
• the molding shrinkage rate in the TD direction during injection molding is preferably 1.0% or less, more preferably 0.9% or less, and further preferably 0.8% or less, from the viewpoint of not damaging the shape of the injection molded product. preferable.
• the mold shrinkage ratios in the MD direction and the TD direction during injection molding are both preferably 0.4% or more, more preferably 0.45% or more. 0.5% or more is more preferable.
• the molding shrinkage ratios in the MD and TD directions during injection molding are both preferably 1.0% or less, more preferably 0.9% or less, and 0.9% or less. 8% or less is more preferable.
• the MD direction during injection molding refers to the flow direction of the molten resin during injection molding
• the TD direction refers to the direction perpendicular to the flow direction.
• the molding shrinkage rates in the MD direction and the TD direction are values measured in accordance with JIS K-7152-4, and specifically refer to values measured by the method described in Examples.
• “molding shrinkage in at least one of the MD direction and the TD direction during injection molding” may be simply referred to as “molding shrinkage.”
• the PVA-based resin composition according to this embodiment contains the PVA-based resin (A).
• the PVA-based resin composition according to the present embodiment preferably contains a PVA-based resin (A) and a mold shrinkage rate modifier (B).
• the PVA-based resin (A) used in the present embodiment is a resin mainly composed of vinyl alcohol structural units, which is obtained by saponifying a polyvinyl ester-based resin obtained by polymerizing a vinyl ester-based monomer.
• the PVA-based resin (A) has a vinyl alcohol structural unit corresponding to the degree of saponification and a vinyl ester structural unit of the unsaponified portion.
• the PVA-based resin (A) used in the present embodiment may be unmodified PVA, or obtained by copolymerizing a vinyl ester-based monomer and various monomers during the production of a vinyl ester-based resin and saponifying this. and various post-modified PVA obtained by introducing various functional groups into unmodified PVA by post-modification. Such modification is preferably carried out to the extent that the water-solubility of the PVA-based resin (A) is not lost. In some cases, the modified PVA may be further post-modified.
• monomers used for copolymerization with vinyl ester-based monomers include, for example, ethylene, propylene, isobutylene, ⁇ -octene, ⁇ -dodecene, ⁇ -octadecene, and the like.
• Olefins acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, unsaturated acids such as itaconic acid or salts thereof, mono- or dialkyl esters thereof; nitriles such as acrylonitrile and methacrylonitrile; amides such as methacrylamide; olefin sulfonic acids such as ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, or salts thereof; alkyl vinyl ethers; N-acrylamidomethyltrimethylammonium chloride; allyltrimethylammonium chloride; N-vinylpyrrolidone; vinyl chloride; vinylidene chloride; polyoxyalkylene (meth)allyl ether such as polyoxyethylene (meth)allyl ether and polyoxypropylene (meth)allyl ether; polyoxyethylene (meth)acrylate, polyoxypropylene (Meth) Polyoxyalkylene (me
• such monomers include 3,4-dihydroxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-hydroxy-1-butene, 4-acyloxy-3-hydroxy-1-butene, 3,4-diacyloxy-2-methyl-1-butene, 4,5-dihydroxy-1-pentene, 4,5-diacyloxy-1-pentene, 4,5-dihydroxy-3-methyl-1-pentene, 4, 5-diacyloxy-3-methyl-1-pentene, 5,6-dihydroxy-1-hexene, 5,6-diacyloxy-1-hexene, glycerin monoallyl ether, 2,3-diacetoxy-1-allyloxypropane, 2 -acetoxy-1-allyloxy-3-hydroxypropane, 3-acetoxy-1-allyloxy-2-hydroxypropane, glycerin monovinyl ether, glycerin monoisopropenyl ether, vinylethylene carbonate, 2,
• the content of these monomers is preferably within a range that does not impair the water solubility of the PVA-based resin (A). is preferably 5 mol % or less.
• Post-modified PVA into which a functional group has been introduced by post-modification includes, for example, those having acetoacetyl groups by reaction with diketene, those having polyalkylene oxide groups by reaction with ethylene oxide, and those having epoxy compounds and the like. Those having a hydroxyalkyl group by reaction, or those obtained by reacting an aldehyde compound having various functional groups with a PVA-based resin can be mentioned.
• the PVA-based resin (A) is preferably a melt-molding PVA-based resin (A1) in consideration of application to various molded products.
• the PVA-based resin for melt-molding is a PVA-based resin suitable for melt-molding capable of hot-melt molding.
• the modified PVA-based resin includes a PVA-based resin containing a structural unit having a primary hydroxyl group in the side chain, or an ethylene-modified PVA-based resin. preferable.
• a PVA-based resin containing a structural unit having a primary hydroxyl group in a side chain is preferable from the viewpoint of excellent melt moldability.
• the number of primary hydroxyl groups in such a structural unit is, for example, preferably 1 to 5, more preferably 1 to 2, still more preferably 1.
• the PVA-based resin containing a structural unit having a primary hydroxyl group in its side chain preferably has a secondary hydroxyl group in addition to the primary hydroxyl group in its side chain.
• PVA-based resins containing structural units having primary hydroxyl groups in side chains include modified PVA-based resins having 1,2-diol structural units in side chains, and hydroxyalkyl group structural units in side chains.
• a modified PVA-based resin and the like can be mentioned.
• modified PVA-based resins containing 1,2-diol structural units in side chains are particularly represented by the following general formula (1): ) is preferably used.
• the portions other than the 1,2-diol structural units are vinyl alcohol structural units and vinyl ester structural units of unsaponified portions, as in ordinary PVA-based resins.
• R 1 to R 4 each independently represent a hydrogen atom or an optionally substituted alkyl group having 1 to 4 carbon atoms, and X represents a single bond or a bond chain. show.
• R 1 to R 4 each independently represent a hydrogen atom or an optionally substituted alkyl group having 1 to 4 carbon atoms. All of R 1 to R 4 are desirably hydrogen atoms from the viewpoint of making the terminal of the side chain a primary hydroxyl group. There may be.
• the alkyl group having 1 to 4 carbon atoms is not particularly limited, and examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and tert-butyl group.
• Examples of the substituent that the alkyl group may have include a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, a sulfonic acid group, and the like.
• X is a single bond or a bond chain.
• X is preferably a single bond in terms of thermal stability and stability under high temperature and acidic conditions.
• the bonding chain is not particularly limited, and examples thereof include hydrocarbon groups such as alkylene groups, alkenylene groups, alkynylene groups, phenylene groups, and naphthylene groups. These hydrocarbon groups may be substituted with halogen groups such as fluorine, chlorine and bromine atoms.
• the connecting chains include -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-, -HPO4-, -Si(OR) 2- , -OSi(OR) 2- , -OSi(OR) 2O- , -Ti(OR)2 - ,- OTi(OR) 2 -, -OTi(OR) 2 O-, -Al(OR)-, -OAl(OR)-, -OAl(OR)O- and the like.
• Each R is independently a hydrogen atom or an arbitrary substituent, preferably a hydrogen atom or an alkyl group, particularly preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
• m is a natural number, preferably 1-10, particularly preferably 1-5.
• X is a bond chain
• X is preferably an alkylene group having 6 or less carbon atoms, more preferably a methylene group or -CH 2 OCH 2 -, from the viewpoints of viscosity stability and heat resistance during production.
• a particularly preferred structure in the 1,2-diol structural unit represented by the general formula (1) is a structure in which R 1 to R 4 are all hydrogen atoms and X is a single bond.
• the saponification degree of the PVA-based resin (A) used in this embodiment is preferably 60 to 100 mol %, for example.
• saponification degree means the value measured based on JISK6726 here.
• the preferred range of the degree of saponification varies depending on the modified species. It is preferably 70 to 90 mol %.
• the degree of saponification is equal to or less than the above upper limit, it is possible to prevent the melting point from becoming too close to the decomposition temperature, thereby facilitating melt molding, which is preferable.
• the degree of saponification is equal to or higher than the above lower limit, since a decrease in water solubility can be suppressed.
• the degree of saponification of the modified PVA-based resin containing 1,2-diol structural units in side chains is, for example, preferably 60 to 99.9 mol%, more preferably 65 to 99.8 mol%, and particularly preferably 70. ⁇ 99.5 mol%. It is preferable that the degree of saponification is equal to or higher than the above lower limit, since a decrease in water solubility can be suppressed.
• the degree of saponification of the ethylene-modified PVA-based resin modified with a small amount of ethylene is, for example, preferably 60 mol% or more, more preferably 70 to 95 mol%, and particularly preferably 71 to 90 mol%.
• the degree of saponification is equal to or less than the above upper limit, it is possible to prevent the melting point from becoming too close to the decomposition temperature, thereby facilitating melt molding, which is preferable.
• the degree of saponification is equal to or higher than the above lower limit, since a decrease in water solubility can be suppressed.
• the modification rate in the modified PVA-based resin that is, the structural units derived from various monomers in the copolymer or the functional groups introduced by post-modification, although the content cannot be generalized because the properties vary greatly depending on the type of structural unit and functional group, it is preferably 0.1 to 20 mol %, for example.
• the modification rate is, for example, preferably 0.1 to 20 mol%, more preferably 0.5 to 10 mol%. and particularly preferably 1 to 8 mol %. It is preferable that the modification rate is within the above range because it facilitates melt molding.
• the content of 1,2-diol structural units in the PVA-based resin is the 1 H-NMR spectrum of the PVA-based resin with a degree of saponification of 100 mol% (solvent: DMSO-d 6 , internal standard: tetramethylsilane).
• the modification rate is, for example, preferably 0.1 to 15 mol%, more preferably 0.5 to 10 mol%. , more preferably 1 to 10 mol %, particularly preferably 5 to 9 mol %. It is preferable that the modification rate is equal to or less than the above upper limit value, since a decrease in water solubility can be suppressed. In addition, it is preferable that the modification rate is equal to or higher than the above lower limit value because it facilitates melt molding.
• the viscosity average degree of polymerization of the PVA-based resin (A) used in the present embodiment is, for example, preferably 100 to 3000, more preferably 150 to 2000, even more preferably 180 to 1000, and particularly preferably 200 to 800. is.
• the viscosity-average degree of polymerization is equal to or less than the upper limit, it is possible to prevent the melt viscosity from becoming too high during melt-molding, thereby facilitating melt-molding.
• the viscosity average degree of polymerization here refers to a value measured according to JIS K 6726.
• the PVA-based resin (A) used in this embodiment may be of one type or a mixture of two or more types.
• two or more types of PVA-based resins (A) for example, a combination of two or more types of unmodified PVA-based resins having different saponification degrees, viscosity-average degrees of polymerization, melting points, etc.; unmodified PVA-based resins and modified Combination with PVA-based resin: Combination of two or more modified PVA-based resins having different degrees of saponification, viscosity-average degree of polymerization, melting point, type of functional group, modification rate, etc., but saponification degree, viscosity
• the average values of the average degree of polymerization, modification rate, etc. are preferably within the preferred ranges of the present embodiment.
• the binding mode of the main chain of the PVA-based resin (A) used in the present embodiment is typically mainly 1,3-diol bonds, and the content of 1,2-diol bonds is, for example, 1.5 to 1 Although it can be about 7 mol %, the content of 1,2-diol bonds can be increased by increasing the polymerization temperature when polymerizing the vinyl ester monomer, and the content is reduced to 1.8 mol %. % or more, or even 2.0 to 3.5 mol %.
• a method for producing the PVA-based resin (A) used in the present embodiment includes, for example, a method of polymerizing and saponifying a vinyl ester-based monomer such as vinyl acetate.
• vinyl ester monomer examples include vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, Vinyl piperate, vinyl octylate, vinyl monochloroacetate, vinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate, vinyl trifluoroacetate and the like can be used.
• vinyl ester-based monomer vinyl acetate is preferably used from the viewpoint of price and availability.
• Polymerization of the vinyl ester monomer can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, and the like. Among them, it is preferable to carry out solution polymerization under reflux because the heat of reaction can be removed efficiently.
• Solvents for solution polymerization include, for example, alcohols, preferably lower alcohols having 1 to 3 carbon atoms.
• the polymer is dissolved in alcohol or a mixed solvent of water and alcohol, and an alkali catalyst or an acid catalyst can be used.
• an alkali catalyst for example, alkali metal hydroxides and alcoholates such as potassium hydroxide, sodium hydroxide, sodium methylate, sodium ethylate, potassium methylate and lithium methylate can be used.
• a transesterification reaction using an alkali catalyst in an anhydrous alcoholic solvent is preferably used in terms of the reaction rate and the ability to reduce impurities such as fatty acid salts.
• the reaction temperature of the saponification reaction is preferably 20 to 60°C, for example.
• the reaction temperature is above a certain level, the reaction rate does not become too low, so the reaction efficiency is less likely to decrease.
• By keeping the reaction temperature below a certain level it is possible to prevent the reaction temperature from becoming equal to or higher than the boiling point of the reaction solvent, and it is easy to ensure safety in terms of production.
• saponification is performed under high pressure using a column type continuous saponification tower with high pressure resistance, saponification can be performed at a higher temperature, for example, 80 to 150 ° C., and a small amount of saponification catalyst is used. Even when using, it is possible to obtain a product with a high degree of saponification in a short time.
• the side chain 1,2-diol structural unit-containing modified PVA-based resin can be produced by a known production method.
• it can be produced by the methods described in JP-A-2002-284818, JP-A-2004-285143, and JP-A-2006-95825.
• the content of the PVA-based resin (A) in the PVA-based resin composition is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. It is preferable that the content of the PVA-based resin (A) in the PVA-based resin composition is 60% by mass or more because the mechanical strength is maintained.
• the upper limit of the content of the PVA-based resin (A) is not particularly limited as long as the molding shrinkage in at least one of the MD direction and the TD direction during injection molding can be 0.4% or more.
• the PVA-based resin composition according to the present embodiment preferably contains a molding shrinkage rate modifier (B).
• B a molding shrinkage rate modifier
• the molding shrinkage rate of the PVA-based resin composition can be adjusted.
• the molding shrinkage rate adjusting agent (B) a substance that can increase the molding shrinkage rate of the PVA-based resin composition compared to the case where the PVA-based resin (A) is used alone is used. It is preferable because it is easy to adjust the rate to a desired value.
• a substance having a property of assisting the crystallization of the PVA-based resin (A) or expanding the shrinkage volume during crystallization is preferable.
• the mold shrinkage rate adjuster (B) is preferably one or more selected from the group consisting of resins other than PVA-based resins, inorganic substances, elastomers and hydrophobic materials.
• resins other than PVA-based resins include chemically synthesized biodegradable resins, microbial-produced resins, and thermoplastic elastomers. More specifically, for example, polybutylene adipate terephthalate, polybutylene succinate, polylactic acid, polybutylene succinate adipate, polyglycolic acid, polyethylene succinate, polycaprolactone, polyethylene terephthalate succinate, polybutylene sebacic acid-co-terephthalate , poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polyhydroxyalkanoic acid, bacterial cellulose, poly 3-hydroxybutyrate, styrene/butadiene/block copolymer, styrene/butadiene/butylene block copolymer polymers, styrene/ethylene/butylene block copolymers, styrene/isoprene block copolymers, styrene/isobut
• resins other than the PVA-based resin include polybutylene adipate terephthalate, polybutylene succinate, polylactic acid, polybutylene succinate adipate, polyglycolic acid, Polyethylene succinate, polycaprolactone, polyethylene terephthalate succinate, polybutylene sebacic acid-co-terephthalate, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), polyhydroxyalkanoic acid, bacterial cellulose, poly 3- Biodegradable resins such as hydroxybutyrate are preferably used.
• the molding shrinkage rate adjuster (B) is more preferably capable of adjusting the molding shrinkage rate of the PVA-based resin composition and adjusting the hydrophilicity of the PVA-based resin composition.
• the PVA-based resin has relatively high hydrophilicity. Therefore, by adjusting the mold shrinkage ratio to the above value with the mold shrinkage ratio adjuster (B) and further making the hydrophilicity of the PVA resin composition relatively small, the releasability of the PVA resin composition is improved. It is preferable because it is easier to improve.
• the molding shrinkage rate modifier (B) is preferably a substance having relatively low hydrophilicity or a hydrophobic substance. succinate, polylactic acid, polycaprolactone, styrene/ethylene/butylene block copolymers, and the like.
• the content of the resin other than the PVA-based resin with respect to the total amount of the PVA-based resin composition is adjusted according to the type of resin, etc. so that the desired molding shrinkage can be obtained. It may be adjusted as appropriate, and is not particularly limited.
• the content is preferably 1% by mass or more, more preferably 5% by mass or more, from the viewpoint of improving releasability from the mold.
• the content is preferably 40% by mass or less, more preferably 30% by mass or less, from the viewpoint of improving mechanical strength.
• inorganic substances include layered inorganic compounds (layered inorganic minerals), and specific examples include talc, calcium carbonate, mica, zeolite, clay, mica, synthetic mica, bentonite, kaolinite (kaolin mineral), pyrophyllite, smectite, vermiculite, chlorite, septe chlorite, serpentine, stilpnomelane, montmorillonite, and the like.
• the molding shrinkage rate adjusting agent (B) the molding shrinkage rate can be adjusted even if the amount added to the PVA-based resin composition is relatively small. It is hard to lose sexuality.
• Talc and calcium carbonate are preferable inorganic substances from the viewpoint of excellent moldability.
• the content of the inorganic substance with respect to the total amount of the PVA-based resin composition may be appropriately adjusted according to the type of the inorganic substance so as to obtain a desired molding shrinkage rate.
• the content is preferably 100 ppm or more, more preferably 500 ppm or more, from the viewpoint of promoting crystallization of the PVA-based resin (A).
• the content is preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of improving moldability.
• ppm means mass ppm here.
• the molding shrinkage rate adjusting agent (B) one type of substance may be used, or two or more types of substances may be used in combination.
• the PVA-based resin composition according to this embodiment may contain other components such as a plasticizer in addition to the components described above.
• plasticizers include compounds obtained by adding ethylene oxide to polyhydric alcohols such as aliphatic polyhydric alcohols such as ethylene glycol, hexanediol, glycerin, trimethylolpropane, and diglycerin; ethylene oxide, propylene oxide, and ethylene oxide; Various alkylene oxides such as mixed adducts of propylene oxide; sugars such as sorbitol, mannitol, pentaerythritol, xylol, arabinose and ribulose; phenol derivatives such as bisphenol A and bisphenol S; amide compounds such as N-methylpyrrolidone; -Glucosides such as D-glucoside;
• the content of the plasticizer is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass of the PVA-based resin (A). 1 to 30 parts by mass, more preferably 2 to 20 parts by mass.
• the content of the plasticizer is at least the above lower limit, melt moldability is likely to be improved, and when it is at most the above upper limit, properties such as gas barrier properties and water solubility of the PVA-based resin are less likely to be impaired, which is preferable.
• thermoplastic resins e.g., polyethylene, polypropylene, polyester, etc.
• fragrances e.g., polyethylene, polypropylene, polyester, etc.
• foaming agents e.g., foaming agents, deodorants, extenders
• fillers e.g., glass beads, glass fibers, silica, Inorganic fillers such as alumina, hydrotalcite, titanium oxide, zirconium oxide, boron nitride and aluminum nitride, organic fillers such as melamine-formalin resins
• release agents e.g., UV absorbers, antioxidants, processing stabilizers, Weather resistance stabilizers, fungicides, preservatives and the like can be mentioned, and these additives can be blended as appropriate.
• the PVA-based resin composition according to the present embodiment can be produced, for example, by a method of appropriately mixing each component constituting the PVA-based resin composition.
• An example of the method for producing the PVA-based resin composition according to the present embodiment includes the following method, but the production method is not limited only to the following method.
• the shape of the PVA-based resin composition according to the present embodiment is preferably cylindrical (pellet-shaped) or powdery, for example. Since the PVA-based resin (A) is generally obtained in the form of powder, it is melt-kneaded together with the molding shrinkage rate adjusting agent (B) to obtain cylindrical pellets made of the PVA-based resin composition according to the present embodiment. It is preferable to obtain raw material pellets.
• Raw material pellets are generally used as raw materials for various melt moldings. ⁇ 2.5 mm. Also, the length of the raw material pellet is preferably 0.5 to 5 mm, more preferably 1 to 4 mm, and particularly preferably 1.5 to 3 mm.
• an extruder to convert the PVA-based resin composition according to the present embodiment into raw material pellets.
• the extruder a single-screw extruder or a twin-screw extruder can be used, but a twin-screw extruder is preferable because sufficient kneading can be obtained by moderate shearing.
• the L/D (screw length/screw diameter) of the extruder is, for example, preferably 10-80, more preferably 15-70, and particularly preferably 20-60. If the L/D is too small, kneading will be insufficient and ejection will tend to be unstable. It tends to cause deterioration.
• the screw rotation speed of the extruder is usually 10 to 1000 rpm, preferably 30 to 700 rpm, particularly preferably 50 to 500 rpm. If the number of revolutions is too low, the discharge tends to be unstable, and if it is too high, excessive shear heat generation tends to cause deterioration of the resin composition.
• the temperature of the resin composition in the extruder cannot be generalized depending on the desired throughput and the like, but it is usually 140 to 280°C, preferably 150 to 260°C, particularly preferably 170 to 240°C. be done.
• the method for adjusting the resin temperature is not particularly limited, but usually a method of appropriately setting the temperature of the cylinder in the extruder or a method of controlling the temperature by the number of revolutions of the extruder is used.
• the PVA-based resin composition according to the present embodiment is suitable for moldings produced by melt molding such as injection molding and extrusion molding (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.).
• melt molding such as injection molding and extrusion molding (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.).
• the PVA-based resin composition according to the present embodiment is manufactured by an injection molding method because the molding shrinkage rate is adjusted to a specific value, so that the injection-molded product can be easily removed from the mold and has excellent releasability. It is particularly suitable for use in injection molded products.
• the present invention relates to an injection-molded article containing the PVA-based resin composition according to this embodiment.
• the method of injection molding is not particularly limited, for example, raw material pellets containing the PVA-based resin composition according to the present embodiment produced by the method described above can be melted and subjected to injection molding.
• the cylinder temperature is preferably 150° C. or higher, more preferably 200° C. or higher, from the viewpoint of melting of the PVA-based resin composition.
• the cylinder temperature is preferably 300° C. or lower, more preferably 250° C. or lower, from the viewpoint of suppressing resin deterioration.
• the mold temperature is preferably 40°C or higher, more preferably 60°C or higher.
• the mold temperature is preferably 100° C. or lower, more preferably 90° C. or lower, from the viewpoint of further improving mold releasability.
• the injection molded article containing the PVA-based resin composition according to the present embodiment has a molding shrinkage rate of 0.4% or more in at least one of the MD direction and the TD direction during injection molding of the PVA-based resin composition. Since the PVA-based resin composition (injection-molded article) can be prevented from closely contacting the mold, it can be easily removed from the mold and has excellent releasability.
• injection-molded articles containing the PVA-based resin composition according to the present embodiment include sheets, rods, plates, pipes, discs, rings, bottle-shaped articles, spheres, polygonal bodies, polygonal bodies, cones, and bicones. A wide variety of shapes such as bodies can be mentioned.
• Such injection-molded products are specifically useful as various packaging materials for electronic components, foods, beverages (coffee capsules, etc.), cosmetics, pharmaceuticals, agricultural chemicals, industrial chemicals, drilling materials, water-soluble cores, and the like. is.
• acetic acid for neutralization was added in an amount of 0.8 equivalent of sodium hydroxide, filtered, washed thoroughly with methanol, dried in a hot air dryer, and modified to contain a side chain 1,2-diol structural unit. A PVA was obtained.
• the degree of saponification of the resulting modified PVA containing 1,2-diol structural units in the side chain is the amount of alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene structural units in the resin. Analysis showed 99 mol %. Also, the viscosity average degree of polymerization was 530 when analyzed according to JIS K6726.
• the content (modified amount) of the 1,2-diol structural unit represented by the formula (1) in the modified PVA containing the 1,2-diol structural unit in the side chain is the integral measured by 1 H-NMR. When calculated from the value, it was 1 mol %.
• the conditions for 1 H-NMR measurement were as follows. Conditions: 300 MHz proton NMR, d 6 -DMSO solution, internal standard substance; tetramethylsilane, 50°C
• PVA-based resin compositions of Examples 1 to 6 and Comparative Example 1 were produced using PVA1 as the PVA-based resin (A).
• Example 1 Talc (manufactured by Nippon Talc Co., Ltd., product number SG-95) was added to the PVA-based resin (A) as a molding shrinkage rate adjusting agent (B) so that the total amount of the PVA-based resin composition was 3000 ppm.
• the mixture was melt-kneaded with a screw extruder (manufactured by Technobell Co., Ltd.), solidified by air cooling, and then cut by a strand cutting method using a cutter to obtain a PVA-based resin composition in the form of pellets.
• Example 2 For the PVA resin (A), talc (manufactured by Nippon Talc Co., Ltd., product number SG-95) as a molding shrinkage rate adjusting agent (B) is 3000 ppm of the total amount of the PVA resin composition, polybutylene adipate terephthalate (PBAT) ( A pellet-shaped PVA-based resin composition was obtained in the same manner as in Example 1, except that ecoflex (registered trademark) manufactured by BASF was added to the total amount of the PVA-based resin composition in an amount of 10% by mass. .
• ecoflex registered trademark
• Example 3 Pellet-shaped pellets were obtained in the same manner as in Example 1, except that PBAT was added to the PVA-based resin (A) as a molding shrinkage rate adjusting agent (B) so as to be 5% by mass of the total amount of the PVA-based resin composition. A PVA-based resin composition was obtained.
• Example 4 Pellet-shaped pellets were obtained in the same manner as in Example 1, except that PBAT was added to the PVA-based resin (A) as a molding shrinkage rate adjusting agent (B) so as to be 10% by mass of the total amount of the PVA-based resin composition. A PVA-based resin composition was obtained.
• Example 5 Pellet-shaped pellets were obtained in the same manner as in Example 1 except that PBAT was added to the PVA-based resin (A) as a molding shrinkage rate modifier (B) so as to be 20% by mass of the total amount of the PVA-based resin composition. A PVA-based resin composition was obtained.
• Example 6 Polybutylene succinate (PBS) (manufactured by Mitsubishi Chemical Corporation, product name: BioPBS) as a molding shrinkage rate adjusting agent (B) is added to the PVA resin (A) so that it becomes 10% by mass of the total amount of the PVA resin composition.
• PBS Polybutylene succinate
• B molding shrinkage rate adjusting agent
• Example 1 A pellet-shaped PVA-based resin composition was obtained in the same manner as in Example 1, except that the PVA-based resin (A) was used alone.
• injection molding The PVA-based resin compositions of Examples 1 to 6 and Comparative Example 1 were injection-molded under the following conditions to obtain injection-molded articles (test pieces).
• Injection molding machine SE100DU-C250 type (manufactured by Sumitomo Heavy Industries, Ltd.) Mold: ISO-D2 (manufactured by Axxicon, mold of type D2 specified in ISO294-3) Size of test piece: length (corresponding to MD direction) 60 mm x width (corresponding to TD direction) 60 mm x thickness 2 mm
• Cylinder temperature: Nozzle/H4/H3/H2/H1/HP 230/230/220/220/210/200°C Mold temperature: 75°C
• the molding shrinkage rate was measured by the following method. After sampling the test pieces, each shot was placed in an aluminum bag and stored. This state was maintained at 23° C. for 24 hours for adjustment (treatment for measuring shrinkage). For the test piece after adjustment, using a caliper (1/100 accuracy, manufactured by Mitutoyo Co., Ltd.), the dimension in the MD direction (flow direction of molten resin during injection molding) and the dimension in the TD direction (perpendicular to the MD direction) was measured. From the measured values, the mold shrinkage in the MD direction and the mold shrinkage in the TD direction were calculated according to the following equations.
• the molding shrinkage rate in the MD direction and the molding shrinkage rate in the TD direction of five test pieces were calculated, and the average values are shown in Table 1. Shown as shrinkage.
• the PVA-based resin compositions of Examples have a mold shrinkage rate of 0.4% or more in at least one of the MD direction and the TD direction during injection molding, so that the mold release property of the injection molded product is excellent. rice field.
• the PVA-based resin composition of the comparative example had a mold shrinkage rate of less than 0.4% in both the MD direction and the TD direction during injection molding, resulting in poor releasability of the injection molded product.

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• 2022
  • 2022-03-28 JP JP2023511256A patent/JPWO2022210529A1/ja active Pending
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• 2023
  • 2023-09-27 US US18/373,564 patent/US20240228744A1/en active Pending

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