Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L87/00—Compositions of unspecified macromolecular compounds, obtained otherwise than by polymerisation reactions only involving unsaturated carbon-to-carbon bonds
  • C08L87/005—Block or graft polymers not provided for in groups C08L1/00 - C08L85/04
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/60—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from the reaction of a mixture of hydroxy carboxylic acids, polycarboxylic acids and polyhydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones

Definitions

• the present invention relates to a resin composition and a resin modifier that are excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance.
• Polylactic acid a bioplastic
• Polylactic acid is made from renewable resources derived from plants such as corn, which are produced by photosynthesis, and is expected to be used in a wide range of fields.
• polylactic acid is known to be brittle, inferior in impact resistance and heat resistance, and easily hydrolyzed, compared to petroleum-based plastics. Therefore, the use of polylactic acid as a resin material may be limited.
• a technique using a stereocomplex of polylactic acid has been considered (see, for example, Patent Document 1).
• Patent Document 2 a technique using a urethane polymer having a lactic acid unit (see, for example, Patent Document 2) and a technique using a composition of a block copolymer of a specific polyester and polylactic acid and polylactic acid (see, for example, Patent Documents 3 and 4) have been considered.
• JP 2011-153275 A International Publication No. 2021/210608 JP 2014-1261 A JP 2001-335623 A
• Final products made from resin materials are required to be hydrolytically resistant to prevent deterioration over time, so bioplastics need to be both biodegradable and hydrolytically resistant depending on the application. Furthermore, from the viewpoint of versatility, final products made of resin materials are desirably excellent in impact resistance and heat resistance. Therefore, the present invention provides a resin composition excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance, and a resin modifier that can improve the biodegradability, hydrolysis resistance, heat resistance, and impact resistance.
• the present inventors have conceived the following invention and found that the problems can be solved. That is, the present invention is as follows.
• the aliphatic diol (b1) has an alkyl group as a branched chain and does not have a quaternary carbon, the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups,
• the aliphatic polyester resin (II) is a polylactic acid resin.
• a resin modifier comprising a block copolymer (I) containing a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b),
• the polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2),
• the aliphatic diol (b1) has an alkyl group as a branched chain and does not have a quaternary carbon
• the resin modifier wherein the two hydroxyl groups in the aliphatic diol (b1) are primary hydroxyl groups.
• the present invention provides a resin composition that is excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance, as well as a resin modifier that can improve biodegradability, hydrolysis resistance, heat resistance, and impact resistance.
• a "polylactic acid unit” means a “structural unit derived from polylactic acid”
• a “polyester unit” means a “structural unit derived from polyester”.
• the "main chain” of a polymer means the longest molecular chain in the polymer molecule, unless otherwise specified.
• the resin composition of the present embodiment contains a block copolymer (I) and an aliphatic polyester resin (II).
• the block copolymer (I) contains a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b), the polyester unit (b) contains a unit derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2), the aliphatic diol (b1) has an alkyl group as a branched chain and does not have a quaternary carbon, the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups, and the melting point of the block copolymer (I) is less than 180°C.
• the resin composition contains the block copolymer (I) having a predetermined structure, the resin composition becomes excellent in biodegradability, hydrolysis resistance, heat resistance, and impact resistance.
• the block copolymer (I) contains a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b), and the polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2), the aliphatic diol (b1) has an alkyl group as a branched chain and has no quaternary carbon, and the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups.
• the resin composition has excellent hydrolysis resistance, heat resistance, and impact resistance.
• the block copolymer (I) that satisfies the above requirements, the resin composition exhibits good biodegradability.
• the block structural unit (B) is likely to form an amorphous structure, when the block copolymer (I) is biodegraded, microorganisms are likely to enter the polymer structure, realizing good biodegradability, and thereby the resin composition also exhibits good biodegradability.
• the biodegradability is further improved by the aliphatic diol (b1) having an alkyl group as a branched chain.
• the block structural unit (B) does not form an amorphous structure, it is considered that microorganisms are unlikely to enter the polymer structure when the block copolymer (I) is biodegraded, and it is considered that it is difficult to obtain the effect of the present invention.
• the fact that the polymer has an amorphous structure is only one factor that affects biodegradability. This is because it is considered that various factors such as whether or not microorganisms recognize the amorphous structure as food, whether enzymes and microorganisms are easily accessible, steric hindrance of the main chain, melting point, crystallinity, etc., affect biodegradability in combination. Therefore, simply having a polymer with an amorphous structure does not necessarily mean that good biodegradability can be obtained.
• the block structural unit (A) is mainly composed of a polylactic acid unit (a).
• the above-mentioned "main component” means the unit that is contained at the highest content ratio among the units constituting the block structural unit (A).
• the content of the polylactic acid unit (a) in the block structural unit (A) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass.
• There is no upper limit to the content of the polylactic acid unit (a) in the block structural unit (A) is, for example, 100% by mass or less.
• the polylactic acid constituting the polylactic acid unit (a) may be prepared by a direct condensation method of lactic acid or by a ring-opening polymerization method of lactide.
• the lactic acid for example, at least one selected from the group consisting of L-lactic acid, D-lactic acid, and DL-lactic acid can be used.
• the lactide for example, at least one selected from the group consisting of L-lactide, D-lactide, DL-lactide, and meso-lactide can be used.
• polylactic acid poly-L-lactic acid, poly-D-lactic acid, poly-DL-lactic acid, and stereocomplex polylactic acid obtained by mixing poly-L-lactic acid and poly-D-lactic acid can be used.
• the polylactic acid is not a stereocomplex polylactic acid.
• the polylactic acid is preferably at least one selected from the group consisting of poly-L-lactic acid, poly-D-lactic acid, and poly-DL-lactic acid, and more preferably at least one selected from the group consisting of poly-L-lactic acid and poly-D-lactic acid.
• the block structural unit (A) contains preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more of structural units derived from poly-L-lactic acid or poly-D-lactic acid.
• the block structural unit (A) is composed of structural units derived from poly-L-lactic acid or structural units derived from poly-D-lactic acid, that is, the structural units derived from poly-L-lactic acid or structural units derived from poly-D-lactic acid account for 100% by mass.
• the block structural unit (A) may or may not contain a unit (a') other than the polylactic acid unit (a).
• the monomer constituting the unit (a') is not particularly limited as long as it does not impair the effects of the present invention.
• the content of units (a') in the block structural unit (A) is preferably 30 mass % or less, more preferably 20 mass % or less, even more preferably 15 mass % or less, and still more preferably 10 mass % or less.
• the number average molecular weight of the block structural unit (A) is preferably 1,000 to 200,000, more preferably 2,000 to 100,000, and even more preferably 3,000 to 50,000. Within the above numerical ranges, productivity tends to be excellent. From the viewpoints of heat resistance and impact resistance, the number average molecular weight of the block structural unit (A) is preferably 5,000 or more, more preferably 7,500 or more, and even more preferably 10,000 or more.
• the number average molecular weight of the block structural unit (A) means the total of all the blocks.
• the number average molecular weight of the block structural unit (A) can be determined from the number average molecular weight of the block copolymer (I) described below and the mass content of the block structural unit (A).
• the block structural unit (B) is mainly composed of a polyester unit (b).
• the above-mentioned "main component” means the unit that is contained in the largest proportion among the units that constitute the block structural unit (B).
• the content of the polyester units (b) in the block structural unit (B) 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 85% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.
• the polyester unit (b) contains units derived from an aliphatic diol (b1) and an aliphatic dicarboxylic acid (b2). Specifically, the polyester unit (b) contains units derived from a polyester obtained by reacting an aliphatic diol (b1) with an aliphatic dicarboxylic acid (b2).
• the polyester unit (b) may or may not contain units derived from monomers other than the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2).
• the monomer other than the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) is not particularly limited as long as the effects of the present invention are not impaired.
• the total amount of the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) in the polyester unit (b) is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more, and may be 100% by mass. There is no upper limit to the total amount of the aliphatic diol (b1) and the aliphatic dicarboxylic acid (b2) in the polyester unit (b), and it is, for example, 100% by mass or less.
• the aliphatic diol (b1) has an alkyl group as a branched chain and has no quaternary carbon, and the two hydroxyl groups in the aliphatic diol (b1) are primary hydroxyl groups.
• the "branched chain” in the aliphatic diol (b1) refers to a partial structure branching off from the "main chain” in the aliphatic diol (b1), and no hydroxyl group is bonded to the end thereof.
• the "main chain” in the aliphatic diol (b1) refers to a partial structure that is a molecular chain composed of a plurality of atoms, preferably carbon atoms, connecting two primary hydroxyl groups in the molecule at both ends. Therefore, the two primary hydroxyl groups in the aliphatic diol (b1) are located at both ends of the "main chain” in the aliphatic diol (b1).
• the block structural unit (B) is less likely to crystallize and has good hydrolysis resistance, so that the block copolymer (I) containing the block structural unit (B) has good biodegradability and good hydrolysis resistance.
• the resin composition containing the block copolymer (I) also has good biodegradability and good hydrolysis resistance.
• the block structural unit (B) since the block structural unit (B) is less likely to crystallize, the block structural unit (B) contains a flexible amorphous structure, and as a result, the impact resistance of the resin composition is good.
• the number of branched chains is preferably 1 or 2, more preferably 1.
• the branched chains are preferably methyl, ethyl, and propyl groups, more preferably methyl and ethyl groups, and even more preferably methyl groups.
• the respective branched chains may be the same or different.
• the block copolymer (I) Since the aliphatic diol (b1) does not have a quaternary carbon, the block copolymer (I) has good biodegradability, and the resin composition containing the block copolymer (I) also has good biodegradability. In addition, the aliphatic diol (b1) easily reacts with the aliphatic dicarboxylic acid (b2), and the block copolymer (I) can be easily produced. When the two hydroxyl groups in the aliphatic diol (b1) are primary hydroxyl groups, the glass transition temperature of the block copolymer (I) tends to decrease, and the impact resistance of the resin composition (particularly the impact resistance at low temperatures of about -40°C to 10°C) is improved. In addition, the aliphatic diol (b1) easily reacts with the aliphatic dicarboxylic acid (b2), and the block copolymer (I) can be easily produced.
• the aliphatic diol (b1) has an alkyl group as a branched chain, does not have a quaternary carbon, and the two hydroxyl groups of the aliphatic diol (b1) are primary hydroxyl groups, so that the block copolymer (I) and the resin composition containing the block copolymer (I) have excellent biodegradability, hydrolysis resistance, and impact resistance.
• the carbon number of the aliphatic diol (b1) is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, from the viewpoint of exhibiting excellent hydrolysis resistance and impact resistance (particularly impact resistance at low temperatures), and is preferably 30 or less, more preferably 18 or less, and even more preferably 9 or less, from the viewpoint of exhibiting even better biodegradability.
• the carbon number of the aliphatic diol (b1) is preferably 4 to 30, more preferably 5 to 18, and even more preferably 6 to 9.
• Examples of the aliphatic diol (b1) include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,4-pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1 ,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,
• the aliphatic diol (b1) is preferably at least one selected from the group consisting of 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,4-diethyl-1,5-pentanediol, and more preferably 3-methyl-1,5-pentanediol.
• the aliphatic diol (b1) may be used alone or in combination of two or more kinds.
• the number of carbon atoms in the aliphatic dicarboxylic acid (b2) is not limited as long as the effects of the present invention are not impaired, but from the viewpoint of exhibiting excellent hydrolysis resistance and impact resistance (particularly impact resistance at low temperatures), it is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, and from the viewpoint of exhibiting even better biodegradability, it is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less. That is, the number of carbon atoms in the aliphatic dicarboxylic acid (b2) is preferably 4 to 12, more preferably 5 to 10, and even more preferably 6 to 8.
• the aliphatic dicarboxylic acid (b2) is preferably a non-cyclic aliphatic dicarboxylic acid from the viewpoint of exerting excellent hydrolysis resistance and impact resistance.
• Examples of the aliphatic dicarboxylic acid (b2) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and decanedicarboxylic acid. At least one selected from the group consisting of succinic acid, adipic acid, and sebacic acid is preferred, at least one selected from succinic acid and adipic acid is more preferred, and adipic acid is even more preferred.
• the aliphatic dicarboxylic acid (b2) may be used alone or in combination of two or more kinds.
• a combination of 3-methyl-1,5-pentanediol and adipic acid, a combination of 3-methyl-1,5-pentanediol and succinic acid, a combination of 2-methyl-1,3-propanediol and adipic acid, a combination of 2-methyl-1,3-propanediol and succinic acid, and a combination of 2,4-diethyl-1,5-pentanediol and adipic acid are examples of preferred embodiments, and a combination of 3-methyl-1,5-pentanediol and adipic acid is an example of a more preferred embodiment.
• the block structural unit (B) may contain a unit (b') other than the polyester unit (b).
• the monomer constituting the unit (b') is not particularly limited as long as it does not impair the effects of the present invention.
• the content of units (b') in the block structural unit (B) is preferably 50 mass % or less, more preferably 30 mass % or less, even more preferably 20 mass % or less, still more preferably 15 mass % or less, and particularly preferably 10 mass % or less.
• the number average molecular weight of the block structural unit (B) may be preferably 1,000 to 300,000, more preferably 5,000 to 200,000, even more preferably 7,000 to 150,000, and still more preferably 9,000 to 100,000. Within the above numerical range, the block copolymer (I) tends to be easily produced. From the viewpoints of heat resistance and impact resistance, the number average molecular weight of the block structural unit (B) is preferably 10,000 or more, more preferably 15,000 or more, even more preferably 20,000 or more, and even more preferably 25,000 or more.
• the number average molecular weight of the block structural unit (B) is preferably 10,000 to 300,000, more preferably 15,000 to 200,000, even more preferably 20,000 to 150,000, and even more preferably 25,000 to 100,000.
• the number average molecular weight of the block structural unit (B) can be determined from the number average molecular weight of the block copolymer (I) described below and the mass content of the block structural unit (B), and specifically, can be measured by the method described in the Examples.
• the content of the block structural unit (A) is preferably 5% by mass or more and 95% by mass or less relative to 100% by mass of the total of the block structural unit (A) and the block structural unit (B).
• the proportion of the block structural unit (A) is 5% by mass or more, the heat resistance of the resin composition tends to be more excellent, and when the proportion of the block structural unit (A) is 95% by mass or less, the hydrolysis resistance, impact resistance, and biodegradability of the resin composition tend to be more excellent.
• the proportion of the block structural unit (A) is more preferably 10% by mass or more, and even more preferably 15% by mass or more.
• the proportion of the block structural unit (A) is more preferably 80% by mass or less, even more preferably 75% by mass or less, still more preferably 70% by mass or less, particularly preferably 60% by mass or less, extremely preferably 50% by mass or less, and most preferably 45% by mass or less.
• the proportion of the block structural unit (A) can be determined by 1 H-NMR, specifically, by the method described in the Examples.
• the total content of the block structural unit (A) and the block structural unit (B) in the block copolymer (I) is preferably 90% by mass or more, more preferably 95% by mass or more, and may be 100% by mass. There is no upper limit to the total content of the block structural unit (A) and the block structural unit (B) in the block copolymer (I), and it may be, for example, 100% by mass or less.
• the block copolymer (I) may or may not contain units other than the block structural unit (A) and the block structural unit (B).
• the units other than the block structural unit (A) and the block structural unit (B) are not particularly limited as long as they do not impair the effects of the present invention.
• the content of units other than the block structural unit (A) and the block structural unit (B) is preferably 10% by mass or less, more preferably 5% by mass or less.
• the bonding form of the block copolymer (I) is preferably a triblock type or a diblock type, and more preferably a triblock type.
• the block copolymer (I) may be a mixture of a triblock type and a diblock type.
• the bonding form is preferably [block structural unit (A)]-[block structural unit (B)]-[block structural unit (A)].
• the number average molecular weight of the block copolymer (I) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more, and from the viewpoints of ease of production and processability, the number average molecular weight of the block copolymer (I) is preferably 400,000 or less, more preferably 200,000 or less, and even more preferably 100,000 or less. That is, the number average molecular weight of the block copolymer (I) is preferably 5,000 to 400,000, more preferably 10,000 to 200,000, and even more preferably 15,000 to 100,000.
• the number average molecular weight of the block copolymer (I) is preferably 20,000 or more, more preferably 25,000 or more, even more preferably 30,000 or more, and even more preferably 35,000 or more. From the viewpoints of heat resistance, impact resistance, ease of production, and processability, the number average molecular weight of the block copolymer (I) is preferably 20,000 to 400,000, more preferably 25,000 to 200,000, and even more preferably 30,000 to 100,000. The number average molecular weight of the block copolymer (I) can be determined by gel permeation chromatography (GPC), specifically, by the method described in the examples.
• GPC gel permeation chromatography
• the melting point of the block copolymer (I) is less than 180°C, preferably 175°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower. From the viewpoint of practical heat resistance, the melting point of the block copolymer (I) is preferably 110° C. or higher, more preferably 120° C. or higher, and even more preferably 125° C. or higher.
• the melting point of the block copolymer (I) is preferably 110°C or more and less than 180°C, more preferably 120°C or more and 175°C or less, even more preferably 120°C or more and 170°C or less, and still more preferably 125°C or more and 160°C or less.
• the melting point of the block copolymer (I) can be determined by a differential scanning calorimeter, specifically, by the method described in the examples.
• the glass transition temperature of the block copolymer (I) is preferably ⁇ 80° C. or higher and ⁇ 15° C. or lower. Within the above numerical range, the resin composition tends to be excellent in flexibility and impact resistance. From the viewpoint of low-temperature properties such as impact resistance at low temperatures, the glass transition temperature of the block copolymer (I) is more preferably ⁇ 20° C. or lower, further preferably ⁇ 25° C. or lower, and in one embodiment of the present invention, it may be ⁇ 30° C. or lower or ⁇ 35° C. or lower. In another embodiment of the present invention, the glass transition temperature of the block copolymer (I) may be ⁇ 45° C. or lower.
• the lower limit of the glass transition temperature of the block copolymer (I) is preferably low, and in one embodiment of the present invention, for example, the glass transition temperature may be ⁇ 70° C. or higher, ⁇ 60° C. or higher, ⁇ 50° C. or higher, or ⁇ 40° C. or higher. In another embodiment of the present invention, the glass transition temperature of the block copolymer (I) may be ⁇ 70° C. or higher, ⁇ 60° C. or higher, or ⁇ 50° C. or higher.
• the glass transition temperature of the block copolymer (I) can be determined by differential scanning calorimetry.
• the block copolymer (I) can be produced by a known production method.
• a known method for producing the block copolymer (I) may be, for example, a method in which a polyester constituting the polyester unit (b) is synthesized and the polyester is polymerized with lactide.
• the polyester can be synthesized by a known method.
• the polyester can be synthesized by reacting an aliphatic diol (b1) with an aliphatic dicarboxylic acid (b2) using an esterification catalyst (e.g., tin octylate, tin chloride, or tin oxide).
• a ring-opening polymerization catalyst e.g., tin octoate, tin chloride, tin oxide.
• the polymerization reaction may be performed by solution polymerization, melt polymerization, interfacial polycondensation, or the like, and any of the polymerization reaction conditions may be set under known polymerization reaction conditions.
• Another known method for producing the block copolymer (I) may be, for example, a method in which a polylactic acid constituting the polylactic acid unit (a) and a polyester constituting the polyester unit (b) are separately synthesized and the polylactic acid and the polyester are reacted with each other.
• Polylactic acid can be synthesized by a known method.
• polylactic acid may be synthesized by reacting lactic acid by a direct condensation method, or polylactic acid may be synthesized by reacting lactide by a ring-opening polymerization method.
• an esterification catalyst e.g., tin octoate, tin chloride, tin oxide.
• the polymerization reaction may be solution polymerization, melt polymerization, interfacial polycondensation, or the like, and any of these may be carried out under known polymerization reaction conditions.
• the aliphatic polyester resin (II) is preferably at least one selected from the group consisting of biomass resins and biodegradable resins from the viewpoint of biodegradability.
• the aliphatic polyester resin (II) include polylactic acid (PLA), polycaprolactone (PCL), poly(caprolactone/butylene succinate) (PCLBS), polybutylene succinate (PBS), poly(butylene succinate/adipate) (PBSA), poly(butylene succinate/carbonate) (PEC), poly(ethylene terephthalate/succinate) (PETS), poly(butylene adipate/terephthalate) (PBAT), poly(tetramethylene adipate/terephthalate) (PTMT), polyethylene succinate (PES), polyglycolic acid (PGA), polyethylene furanoate (PEF), polyhydroxyalkanoate (PHA) [e.g., polyhydroxybutyrate
• the aliphatic polyester resin (II) is preferably PLA, PBS, PBSA, or PBAT, and more preferably PLA or its copolymer, i.e., polylactic acid resin.
• examples of the polylactic acid resin include at least one selected from the group consisting of a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, a homopolymer of DL-lactic acid, a copolymer of DL-lactic acid and L-lactic acid, a copolymer of DL-lactic acid and D-lactic acid, and a polymer of lactide, which is a cyclic dimer of lactic acid.
• the polylactic acid resin may be a copolymer of lactic acid with an aliphatic hydroxycarboxylic acid other than lactic acid, an aliphatic dicarboxylic acid, an aliphatic diol, an aromatic dicarboxylic acid, etc.
• the copolymer preferably contains 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more of structural units derived from lactic acid.
• the polylactic acid-based resin a homopolymer of L-lactic acid, a homopolymer of D-lactic acid, or a copolymer of L-lactic acid and D-lactic acid is preferable, and a homopolymer of L-lactic acid is more preferable.
• the polylactic acid resin may be used alone or in combination of two or more kinds.
• the polylactic acid resin may be a commercially available product.
• commercially available products include the "INGEO series” manufactured by Natureworks, the "Luminy series” manufactured by TOTAL CORBION, the “Revode” series manufactured by Zhejiang Hisun Biomaterials Co., Ltd., and the "SUPLA” series manufactured by SUPLA Material Technology Co., Ltd.
• the weight average molecular weight of the polylactic acid resin is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more from the viewpoints of impact resistance and heat resistance, and is preferably 600,000 or less, more preferably 550,000 or less, and even more preferably 500,000 or less from the viewpoints of moldability and compatibility with the block copolymer (I). That is, the weight average molecular weight of the polylactic acid resin is preferably 50,000 to 600,000, more preferably 100,000 to 550,000, and even more preferably 150,000 to 500,000.
• the weight average molecular weight of the polylactic acid resin can be determined by gel permeation chromatography (GPC) measurement in terms of standard polystyrene. When a commercially available product is used, the value listed in the catalog may be used.
• the resin composition of this embodiment contains the block copolymer (I) in an amount of preferably 0.5 to 50% by mass, more preferably 1 to 40% by mass, even more preferably 1.5 to 30% by mass, and even more preferably 2 to 20% by mass, based on 100% by mass of the total of the block copolymer (I) and the aliphatic polyester resin (II).
• the above content ratios make it possible to obtain a resin composition having even better hydrolysis resistance, heat resistance, and impact resistance.
• the resin composition of this embodiment contains preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, even more preferably 70 to 98.5% by mass, and even more preferably 80 to 98% by mass of the aliphatic polyester resin (II) relative to 100% by mass of the total of the block copolymer (I) and the aliphatic polyester resin (II).
• the above content ratios make it possible to obtain a resin composition with even better hydrolysis resistance, heat resistance, and impact resistance.
• the resin composition of this embodiment contains block structural units (A) in an amount of preferably 0.1 to 40% by mass, more preferably 0.3 to 30% by mass, even more preferably 0.5 to 25% by mass, and even more preferably 1 to 15% by mass, relative to 100% by mass of the total of the block copolymer (I) and the aliphatic polyester resin (II).
• the above content ratios make it possible to obtain a resin composition with even better hydrolysis resistance, heat resistance, and impact resistance.
• the resin composition of this embodiment contains block structural units (B) in an amount of preferably 0.2 to 40% by mass, more preferably 0.5 to 30% by mass, even more preferably 1 to 20% by mass, and even more preferably 1.5 to 15% by mass, relative to 100% by mass of the total of the block copolymer (I) and the aliphatic polyester resin (II).
• the above content ratios make it possible to obtain a resin composition with even better hydrolysis resistance, heat resistance, and impact resistance.
• the total content of the block copolymer (I) and the aliphatic polyester resin (II) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more.
• the total content of the block copolymer (I) and the aliphatic polyester resin (II) may be 100% by mass or less. With the above content ratio, the effect of the present invention is more significantly exhibited.
• the resin composition of this embodiment may contain, in addition to the block copolymer (I) and the aliphatic polyester resin (II), a plasticizer, a resin other than the aliphatic polyester resin (II), and other additives.
• a plasticizer may be added to adjust the viscosity of the resin composition to a level suitable for molding, to obtain a molded product having a desired hardness, etc.
• the plasticizer is not particularly limited, but is preferably a plasticizer that is biodegradable in any of industrial compost, home compost, soil, and marine environments. Suitable examples include vegetable esters such as rapeseed oil and castor oil, synthetic esters such as triacetin, diethyl phthalate, and triethyl citrate, polyols such as ethylene glycol and trimethylolpropane, and derivatives thereof, and sugars such as sorbitol. These may be used alone or in combination of two or more.
• the resin other than the aliphatic polyester resin (II) is not particularly limited, but is preferably a resin that is biodegradable in any of the environments of industrial compost, household compost, soil, and marine. Suitable examples include polyvinyl alcohol, cellulose resins such as cellulose acetate, starch and its esters, and 4-nylon. These may be used alone or in combination of two or more.
• the resin composition of this embodiment may contain additives other than the block copolymer (I) and the aliphatic polyester resin (II).
• additives include inorganic fillers, softeners, heat aging inhibitors, antioxidants, hydrolysis inhibitors, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, brightening agents, ultraviolet absorbers, lubricants, etc. These may be used alone or in combination of two or more. When the above additives are used, the content of the additives in the resin composition may be appropriately determined depending on the desired physical properties of the resin composition.
• Method of producing resin composition There is no particular limitation on the method for producing the resin composition of this embodiment, and it is sufficient to uniformly mix the block copolymer (I), the aliphatic polyester resin (II), and, if necessary, additives.
• the mixing method include a method of melt-kneading using a single-screw extruder, a multi-screw extruder, a Banbury mixer, a heating roll, a Brabender, various kneaders, etc., or a method of feeding each component through a separate inlet and melt-kneading the components. Alternatively, they may be preblended before melt-kneading.
• Examples of the preblending method include a method using a mixer such as a Henschel mixer, a high-speed mixer, a V blender, a ribbon blender, a tumbler blender, or a conical blender.
• the temperature during melt-kneading can be arbitrarily selected, preferably within the range of 140 to 220° C., taking into consideration the melting points and decomposition temperatures of the block copolymer (I) and the aliphatic polyester resin (II).
• the block copolymer (I) can have improved hydrolysis resistance, heat resistance, and impact resistance by being mixed with an aliphatic polyester resin (II) to form a resin composition. Therefore, the present invention provides a resin modifier comprising a block copolymer (I). In addition, the use of the block copolymer (I) as a resin modifier for the aliphatic polyester resin (II) is also a preferred embodiment.
• the compounds used in the examples and comparative examples are as follows. 3-Methyl-1,5-pentanediol (Kuraray Co., Ltd.) Adipic acid (Tokyo Chemical Industry Co., Ltd.) Stannous octoate (Tokyo Chemical Industry Co., Ltd.) Toluene (Kishida Chemical Co., Ltd.) L-lactide (Tokyo Chemical Industry Co., Ltd.) D-Lactide (Tokyo Chemical Industry Co., Ltd.) Methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Succinic acid (Tokyo Chemical Industry Co., Ltd.) 2-Methyl-1,3-propanediol (Tokyo Chemical Industry Co., Ltd.) 2,4-Diethyl-1,5-pentanediol (Tokyo Chemical Industry Co., Ltd.) Propylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)
• the physical properties of the block copolymer, polymer and resin composition in the examples and comparative examples were measured or evaluated by the following methods.
• Mn Number average molecular weight
• the number average molecular weights (Mn) of the block copolymer and polymer were determined in terms of standard polystyrene by gel permeation chromatography (GPC).
• GPC gel permeation chromatography
• the Mn of the block structural unit (B) was determined from the Mn of the block copolymer and the mass content of the block structural unit (B)
• the Mn of the block structural unit (B') was determined from the Mn of the block copolymer and the mass content of the block structural unit (B').
• Biodegradability (composting) of the resin composition The biodegradability of the resin composition in compost was measured according to the method of ISO 14855-2: 2018. If the decomposition rate after 15 days was 10% by mass or more, it was rated as A, and if it was less than 10% by mass, it was rated as B.
• a V-notch processing (remaining width 8 mm, tip radius 0.25 mm) was performed on the center of the long side to prepare a notched rectangular test piece.
• ⁇ Impact strength measurement> The notched rectangular test piece prepared using the resin composition was stored at 23°C and 49% humidity for 24 hours or more, and the impact strength was measured at 23°C and 49% humidity with a hammer load of 2 J using a Charpy impact tester ("DG-CB" manufactured by Toyo Seiki Seisakusho Co., Ltd.). The measured value was the average value of 5 measurements.
• test piece for hydrolysis resistance was prepared in the same manner as described in ⁇ Preparation of test piece for deflection temperature under load> above.
• ⁇ Hydrolysis resistance test> The deflection temperature under load (1) was measured by using the strip test piece prepared using the resin composition in the same manner as described in ⁇ Measurement of deflection temperature under load> above.
• a test piece prepared in the same manner as the strip test piece used to measure the deflection temperature under load (1) was immersed in 100 mL of ion-exchanged water with a pH of 7, left to stand at 50° C. for one week, removed, and stored at 23° C.
• the deflection temperature under load (2) was measured using the strip test piece in the same manner as in the above ⁇ Measurement of deflection temperature under load>.
• the difference between the deflection temperature under load (1) and the deflection temperature under load (2) was less than 5° C., it was rated as A, and when it was 5° C. or more, it was rated as B.
• the pressure was reduced to 2,000 Pa and the reaction was carried out for 3 hours, and then the pressure was reduced to 80 Pa and the reaction was carried out while appropriately checking until the number average molecular weight reached 9,500, thereby synthesizing a polymer consisting of structural units (B') mainly composed of polyester units.
• the pressure was returned to normal pressure, the temperature was cooled to 80 ° C., and then toluene was added to dilute the solid content concentration to 40% by mass, and the above toluene solution was added to methanol in an amount twice the total amount of the solution. The supernatant was discarded, and the same amount of methanol as the amount of the toluene solution added was added again for washing.
• the mixture was cooled to 80°C, and a polymer consisting of structural unit (B') and L-lactide were added so that the mass ratio of polymer consisting of structural unit (B')/L-lactide was 50/50, and toluene was added in the amount of the weight of the distilled off solution described above to adjust the solid content concentration to 50 mass%.
• the mixture was heated to 100°C, and tin octylate was added in an amount of 0.1 mass% relative to the polymer consisting of structural unit (B'), and the mixture was allowed to react for 4 hours to obtain a toluene solution of a block copolymer consisting of block structural unit (A) mainly composed of polylactic acid unit (a) and block structural unit (B) mainly composed of polyester unit (b).
• Toluene was added to this solution to dilute the solid content to 40% by mass, and the above toluene solution was then poured into methanol in an amount twice the total amount of the solution to precipitate a solid.
• a block copolymer (I-1) consisting of a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b).
• the above measurements were carried out on the obtained block copolymer (I-1), and the results are shown in Table 1-1.
• a block copolymer (I-2) composed of a block structural unit (A) composed of a polylactic acid unit (a) as a main unit and a block structural unit (B) composed of a polyester unit (b) as a main unit was synthesized in the same manner as in Production Example 1, except that the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural unit (B') composed of polyester unit (b) as a main unit, the mass ratio of L-lactide used was changed, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-2), and the results are shown in Table 1-1.
• a block copolymer (I-3) composed of a block structural unit (A) having a polylactic acid unit (a) as a main unit and a block structural unit (B) having a polyester unit (b) as a main unit was synthesized in the same manner as in Production Example 1, except that succinic acid was used instead of adipic acid, the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural unit (B') having a polyester unit as a main unit, the mass ratio of L-lactide used was changed, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-3), and the results are shown in Table 1-1.
• a block copolymer (I-4) composed of a block structural unit (A) having a polylactic acid unit (a) as a main unit and a block structural unit (B) having a polyester unit (b) as a main unit was synthesized in the same manner as in Production Example 1, except that 2-methyl-1,3-propanediol was used instead of 3-methyl-1,5-pentanediol, the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural unit (B') having polyester units as main units, the mass ratio of L-lactide used was changed, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-4), and the results are shown in Table 1-1.
• a block copolymer (I-5) composed of a block structural unit (A) having polylactic acid units (a) as main units and a block structural unit (B) having polyester units (b) as main units was synthesized in the same manner as in Production Example 1, except that 2-methyl-1,3-propanediol was used instead of 3-methyl-1,5-pentanediol, succinic acid was used instead of adipic acid, the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural units (B') having polyester units as main units, the mass ratio of L-lactide used was changed, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-5), and the results are shown in Table 1-1.
• a block copolymer (I-6) composed of a block structural unit (A) having polylactic acid units (a) as main units and a block structural unit (B) having polyester units (b) as main units was synthesized in the same manner as in Production Example 1, except that 2,4-diethyl-1,5-pentanediol was used instead of 3-methyl-1,5-pentanediol, the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural units (B') having polyester units as main units, the mass ratio of L-lactide used was changed, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-6), and the results are shown in Table 1-1.
• Block copolymers (I-7) to (I-14) composed of block structural units (A) composed mainly of polylactic acid units (a) and block structural units (B) composed mainly of polyester units (b) were synthesized in the same manner as in Production Example 1, except that the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of structural units (B') composed mainly of polyester units (b), the mass ratio of L-lactide used was changed, and the dilution concentration during synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the resulting block copolymers (I-7) to (I-14), and the results are shown in Tables 1-2 to 1-4.
• the above measurements were carried out on the obtained block copolymer (I-15), and the results are shown in Table 1-4.
• a block copolymer (I-16) composed of a block structural unit (A) composed mainly of a polylactic acid unit (a) and a block structural unit (B) composed mainly of a polyester unit (b) was synthesized in the same manner as in Production Example 15, except that the number average molecular weight was adjusted by adjusting the reaction time during the synthesis of a polymer composed of a structural unit (B') composed mainly of a polyester unit (b), the mass ratio of L-lactide to D-lactide used was set to 80:20, and the dilution concentration during the synthesis was appropriately changed to a concentration that was easy to handle.
• the above measurements were carried out on the obtained block copolymer (I-16), and the results are shown in Table 1-4.
• Block copolymer (I'-1) was synthesized in the same manner as in Production Example 1, except that propylene glycol was used instead of 3-methyl-1,5-pentanediol, succinic acid was used instead of adipic acid, the number average molecular weight was adjusted by adjusting the reaction time during synthesis of the polymer consisting of structural units (C') having polyester units as main units, the mass ratio of L-lactide used was changed, and the dilution concentration during synthesis was appropriately changed to a concentration that was easy to handle. The above measurements were carried out on the resulting block copolymer (I'-1). The results are shown in Table 2.
• Examples 1 to 21 and Comparative Examples 2 and 3 The block copolymers and polymers obtained in the Production Examples, and the polylactic acid polymer "INGEO 2500HP" (manufactured by Nature Works) as the aliphatic polyester resin (II) were charged into a kneading machine Labo Plastomill (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "3S150", roller mixer model "R60”) in the formulations shown in Tables 1 and 2, and melt-kneaded for 5 minutes at a cylinder temperature of 210°C and a screw rotation speed of 50 rpm to obtain a resin composition. The obtained resin composition was subjected to the above measurements and evaluations. The results are shown in Tables 1-1 to 1-4 and 2.
• Example 1 A resin composition was obtained in the same manner as in Example 1, except that the block copolymer (I) was not used and the aliphatic polyester resin (II) was changed to the composition shown in Table 2. The resin composition thus obtained was subjected to the above-mentioned measurements and evaluations. The results are shown in Table 2.
• PLLA Poly L-lactic acid
• PDLLA Poly DL-lactic acid
• MPD 3-methyl-1,5-pentanediol
• DEPD 2,4-diethyl-1,5-pentanediol
• MPDiol 2-methyl-1,3-propanediol
• Adipic acid SA Succinic acid
• PG Propylene glycol
• the resin composition of this embodiment which contains a block copolymer (I) containing a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b) having a specific structure, and an aliphatic polyester resin (II), was confirmed to have excellent hydrolysis resistance from the hydrolysis resistance evaluation.
• the resin composition of this embodiment has excellent impact resistance from the impact strength measurement, and excellent heat resistance from the load deflection temperature measurement.
• the resin composition of this embodiment has excellent biodegradability and excellent transparency.
• the block copolymer (I) containing a block structural unit (A) mainly composed of a polylactic acid unit (a) and a block structural unit (B) mainly composed of a polyester unit (b) having a specific structure is suitable for use as a resin modifier.
• the resin composition obtained in Comparative Example 1 was inferior in impact resistance since it did not contain the block copolymer (I).
• the resin composition obtained in Comparative Example 2 was inferior in hydrolysis resistance, impact resistance, and transparency. This result was probably due to the use of a polyester polymer obtained by reacting propylene glycol with succinic acid, rather than a block copolymer.
• the resin composition obtained in Comparative Example 3 was inferior in hydrolysis resistance and impact resistance, similar to Comparative Example 2.
• the reason for this result is considered to be that the block copolymer contains, as a structural unit, propylene glycol in which the two hydroxyl groups in the diol are not primary hydroxyl groups.
• the resin composition of this embodiment has excellent biodegradability, hydrolysis resistance, impact resistance, and heat resistance. Furthermore, the block copolymer (I) is suitable for use as a resin modifier. Therefore, the industrial usefulness of the resin composition and resin modifier of this embodiment is extremely high.

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• 2023
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