Polylactic acid-based resin composition and use of the same

Abstract

To provide a polylactic acid resin composition which is excellent in flexibility.SOLUTION: A resin composition contains a polylactic acid-based resin and a polyhydroxyalkanoic acid-based resin, wherein a ratio of the polyhydroxyalkanoic acid-based resin is 2 to 50 pts.mass with respect to 100 pts.mass of the polylactic acid-based resin. The polyhydroxyalkanoic acid-based resin may contain a hydroxy C4-10 alkanoic acid component (especially, hydroxy C4-6 alkanoic acid component) as a polymerization component. The polyhydroxyalkanoic acid-based resin may contain at least one selected from the group consisting of (R)-3-hydroxybutyric acid component and (R)-3-hydroxyvaleric acid component as a polymerization component. A ratio of the polyhydroxyalkanoic acid-based resin may be 3 to 30 pts.mass with respect to 100 pts.mass of the polylactic acid-based resin. A melt flow rate of the resin composition may be 1 to 30 g / 10 min.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polylactic acid resin composition containing a polyhydroxyalkanoic acid resin and uses thereof. [Background technology]

[0002] There is a strong demand for efforts to realize a "low-carbon society" by reducing greenhouse gas emissions and a "resource-circulating society" that is in harmony with the environment, and the spread of a new material called "bioplastics" is accelerating in order to realize such a society.

[0003] Among these, polylactic acid is used as a plant-derived, biodegradable resin, but it is a hard resin and lacks flexibility for use as a film. This has led to the problem that films cannot be made with polylactic acid as the main component. Other plant-derived, biodegradable resins, such as polyhydroxyalkanoates, are also hard and difficult to use as resins for films. Therefore, a method is known in which additives (plasticizers) are added to increase flexibility in order to give the resin a flexibility suitable for film formation.

[0004] JP 2011-52149 A (Patent Document 1) discloses a polylactic acid resin composition that is composed of polylactic acid, a plasticizer for plasticizing polylactic acid, and a polymer having a thickening effect.

[0005] Japanese Patent Laid-Open Publication No. 2015-193750 (Patent Document 2) discloses a resin composition containing a hard biodegradable resin such as a polylactic acid resin, a soft biodegradable resin, a plasticizer, and at least one compound selected from the group consisting of fatty acid amide compounds, aliphatic monoepoxy compounds, and aliphatic monocarboxylic acid compounds. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-52149 A [Patent Document 2] JP 2015-193750 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the resin compositions of Patent Documents 1 and 2 have problems such as the plasticizer bleeding out, the glass transition temperature of the resin being lowered by the plasticizer, and the heat resistance of the film being reduced. In order to avoid these problems, it is necessary to adopt a method of reducing the amount of plasticizer used or a method of not using plasticizer at all, but such conventional techniques cannot impart flexibility.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a polylactic acid resin composition having excellent flexibility and uses thereof. [Means for solving the problem]

[0009] As a result of intensive research to solve the above-mentioned problems, the inventors discovered that the flexibility of a polylactic acid-based resin composition can be improved by combining a specified amount of a polyhydroxyalkanoic acid-based resin with a polylactic acid-based resin, and thus completed the invention.

[0010] That is, the resin composition of aspect [1] of the present invention is a resin composition containing a polylactic acid-based resin and a polyhydroxyalkanoic acid-based resin, and the proportion of the polyhydroxyalkanoic acid-based resin is 2 to 50 parts by mass per 100 parts by mass of the polylactic acid-based resin.

[0011] The present invention relates to an aspect [2] of the present invention, wherein the polyhydroxyalkanoic acid resin is a hydroxyalkanoic acid. 4-10 This is an embodiment in which an alkanoic acid component is contained as a polymerization component.

[0012] The present invention relates to an aspect [3] of the present invention, wherein the polyhydroxyalkanoic acid resin is a hydroxyalkanoic acid. 4-6 This is an embodiment in which an alkanoic acid component is contained as a polymerization component.

[0013] Aspect [4] of the present invention is any one of aspects [1] to [3] above, wherein the polyhydroxyalkanoic acid resin contains at least one component selected from the group consisting of an (R)-3-hydroxybutyric acid component and an (R)-3-hydroxyvaleric acid component as a polymerization component.

[0014] An embodiment [5] of the present invention is any one of the above embodiments [1] to [4], wherein the polyhydroxyalkanoic acid resin contains an (R)-3-hydroxybutyric acid component as a polymerization component.

[0015] Aspect [6] of the present invention is any one of aspects [1] to [5] above, wherein the proportion of the polyhydroxyalkanoic acid resin is 3 to 30 parts by mass per 100 parts by mass of the polylactic acid resin.

[0016] The embodiment [7] of the present invention is an embodiment in which the resin composition of any one of the above embodiments [1] to [6] has a melt flow rate of 1 to 30 g / 10 min at a temperature of 190° C. and a load of 2.16 kgf.

[0017] The embodiment [8] of the present invention is an embodiment in which the resin composition of any one of the above embodiments [1] to [7] is substantially free of a plasticizer.

[0018] The present invention also includes, as an embodiment [9], a molded article formed from the resin composition according to any one of the embodiments [1] to [8] above.

[0019] The embodiment

[10] of the present invention is an embodiment in which the molded article of the embodiment [9] is a film or sheet.

[0020] The present invention also includes, as aspect

[11] , a method for improving the flexibility of a resin composition comprising a polylactic acid-based resin and a polyhydroxyalkanoic acid-based resin, by adjusting the proportion of the polyhydroxyalkanoic acid to 2 to 50 parts by mass per 100 parts by mass of the polylactic acid-based resin.

[0021] In this specification and claims, the number of carbon atoms of a substituent is represented as C1, C6, C 10 For example, "C1 alkyl group" means an alkyl group with one carbon atom, and "C 6-10 The term "aryl group" refers to an aryl group having 6 to 10 carbon atoms.

[0022] In this specification and claims, 2-10 "Alkanoic acid" means that the total number of carbon atoms in the alkanoic acid, including the carbon number of the carboxyl group, is 2 to 10.

[0023] Furthermore, when a numerical range is indicated using "to" in this specification and the claims, it is intended to include both ends of the numerical range.

[0024] Furthermore, in this specification and claims, the terms "carboxylic acid component" and "hydroxycarboxylic acid component" are used to mean not only carboxylic acids and hydroxycarboxylic acids, but also reactive derivatives thereof. Effect of the Invention

[0025] The resin composition of the present invention contains a predetermined amount of polyhydroxyalkanoic acid resin relative to the polylactic acid resin, and therefore can improve flexibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The resin composition of the present invention contains a predetermined amount of polyhydroxyalkanoic acid resin relative to the polylactic acid resin. Surprisingly, although both resins are hard polymer resins, by combining the two resins in a specific ratio, the resin composition of the present invention has excellent flexibility without adding a plasticizer. In particular, the resin composition of the present invention can improve mechanical properties such as impact strength, and in addition, despite the combination of highly crystalline resins, the resin composition of the present invention has high melt fluidity and moldability. In addition, since both resins in the resin composition of the present invention are both highly biodegradable, unlike conventional polylactic acid resins, the resin composition of the present invention can achieve both biodegradability and flexibility. Furthermore, despite the combination of different resins, the resin composition of the present invention has excellent transparency, and in particular, by adjusting the ratio of the polyhydroxyalkanoic acid resin to a small amount, the transparency of the resin composition can be further improved.

[0027] [Polylactic acid resin] The resin composition of the present invention contains a polylactic acid resin. The polylactic acid resin is a resin (polymer) containing a lactic acid component as a polymerization component. The lactic acid component may be lactic acid (2-hydroxypropanoic acid or 2-hydroxypropionic acid) or a reactive derivative of lactic acid.

[0028] Lactic acid may be an optical isomer (D- or L-isomer) or a racemic mixture (DL-isomer), but from the standpoint of mechanical properties and the like, it is preferable to include the L-isomer (L-lactic acid).

[0029] When the lactic acid contains an L-form, the proportion of the L-form in the lactic acid is preferably 10 mol % or more, more preferably 50 mol % or more, and even more preferably 90 mol % or more.

[0030] When the lactic acid is a combination of L- and D-forms (D-lactic acid), the molar ratio of the L- and D-forms, L- / D-form, may be 99.9 / 0.1 to 10 / 90, for example, 99.5 / 0.5 to 50 / 50, preferably 99 / 1 to 70 / 30, further preferably 98 / 2 to 80 / 20, more preferably 97 / 3 to 90 / 10, and most preferably 96 / 4 to 93 / 7.

[0031] Reactive derivatives of lactic acid include lactide (lactic acid dimer), acid anhydride, methyl ester, and other C 1-3 Examples of the acid halide include alkyl esters and acid chlorides.

[0032] These lactic acid components can be used alone or in combination of two or more. Among these lactic acid components, lactic acid components containing L-lactic acid [(S)-2-hydroxypropanoic acid] or its reactive derivatives are preferred, and a combination of L-lactic acid and D-lactic acid [(R)-2-hydroxypropanoic acid] is particularly preferred.

[0033] The polylactic acid resin is preferably a polymer having a lactic acid component as the main polymerization component, and may be a homopolymer of a lactic acid component (e.g., poly D-lactic acid, poly L-lactic acid, poly D,L-lactic acid, etc.) or a copolymer of a lactic acid component and a copolymerization component.

[0034] Examples of copolymerizable components with the lactic acid component include diols, dicarboxylic acid components, hydroxycarboxylic acid components, and lactones.

[0035] The diol is not particularly limited and may be any of aliphatic diols, alicyclic diols, and aromatic diols, but aliphatic diols are preferred from the viewpoint of biodegradability, etc. Examples of aliphatic diols include C 11 diols such as ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, hexanediol, and octamethylene glycol. 2-10 Aliphatic diols, etc. These diols can be used alone or in combination of two or more kinds.

[0036] Of these diols, C 2-8 Aliphatic diols are preferred, and C diols such as ethylene glycol, 1,4-butanediol, and neopentyl glycol are preferred. 2-6 Alkanediols are particularly preferred.

[0037] The dicarboxylic acid component is not particularly limited and may be any of an aliphatic dicarboxylic acid component, an alicyclic dicarboxylic acid component, and an aromatic dicarboxylic acid component. From the viewpoint of biodegradability, an aliphatic dicarboxylic acid component is preferred.

[0038] The aliphatic dicarboxylic acid component may be an aliphatic dicarboxylic acid or a reactive derivative of an aliphatic dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include C 11 acid such as oxalic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. 2-10 Examples of reactive derivatives of aliphatic dicarboxylic acids include acid anhydrides and methyl esters. 1-3 Examples of the dicarboxylic acid component include alkyl esters, acid halides such as acid chlorides, etc. These dicarboxylic acid components can be used alone or in combination of two or more kinds.

[0039] Of these dicarboxylic acid components, C 2-8 Aliphatic dicarboxylic acids or their reactive derivatives are preferred, and C carboxylic acids such as oxalic acid, succinic acid, and adipic acid are preferred. 2-6 Alkanedicarboxylic acids or reactive derivatives thereof are particularly preferred.

[0040] The hydroxycarboxylic acid component may be any of a hydroxyaliphatic carboxylic acid component, a hydroxyalicyclic carboxylic acid component, and a hydroxyaromatic carboxylic acid component, but from the standpoint of biodegradability and the like, a hydroxyaliphatic carboxylic acid component is preferred.

[0041] The hydroxyaliphatic carboxylic acid component may be a hydroxyaliphatic carboxylic acid or a reactive derivative of a hydroxyaliphatic carboxylic acid.

[0042] Hydroxyaliphatic carboxylic acids include glycolic acid, 3-hydroxypropanoic acid (3HP), 2-hydroxybutyric acid (2-hydroxybutanoic acid), 3-hydroxybutyric acid (3HB), 4-hydroxybutyric acid (4HB), 3-hydroxy-3-methyl-butyric acid, 2-hydroxyvaleric acid (2-hydroxypentanoic acid), 3-hydroxyvaleric acid (3HV), 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxy-2-methyl-valeric acid, 3-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 3-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 3-hydroxynananoic acid, 9-hydroxynananoic acid, 3-hydroxydecanoic acid, and 10-hydroxydecanoic acid. 1-6 Hydroxy C, optionally having an alkyl group 2-15 Alkanoic acid and the like.

[0043] Reactive derivatives of hydroxyaliphatic carboxylic acids include acid anhydrides, methyl esters, and other C 1-3 Examples of the suitable alkyl esters include acid halides such as acid chlorides, and lactones corresponding to hydroxyaliphatic carboxylic acids.

[0044] Lactones include di-C lactones such as glycolide, β-propiolactone, β-dimethylpropiolactone, γ-butyrolactone, γ-dimethylbutyrolactone, δ-valerolactone, and ε-caprolactone. 1-6 C which may have an alkyl group 3-15 These lactones can be used alone or in combination of two or more. Among these lactones, C 3-10 Lactones are preferred, and C such as glycolide, propiolactone, and caprolactone. 4-8 Lactones are particularly preferred.

[0045] These hydroxycarboxylic acid components can be used alone or in combination of two or more.

[0046] Of these hydroxycarboxylic acid components, hydroxy C 2-10Alkanoic acid or a reactive derivative thereof is preferred, and hydroxy C 2-8 Alkanoic acid or its reactive derivatives are more preferred, and hydroxy C such as glycolic acid and 3-hydroxypropanoic acid are preferred. 2-6 Alkanoic acids or reactive derivatives thereof are more preferred.

[0047] These copolymerization components can be used alone or in combination of two or more. Among these copolymerization components, C 2-4 C such as alkanediols, adipic acid, etc. 2-6 Alkanedicarboxylic acid components, such as hydroxy C, glycolic acid, etc. 2-4 Alkanoic acid components, such as glycolide and caprolactone 4-6 Lactones are preferred. The copolymerization components may be any copolymerization components other than the 3-hydroxybutyric acid component.

[0048] In the polylactic acid resin, the proportion of the lactic acid component, which is a monomer, may be the maximum proportion of all the constituent monomers, and may be, for example, 50 mol% or more (e.g., about 50 to 99.5 mol%) of all the constituent monomers, preferably 70 mol% or more (e.g., about 70 to 99 mol%), more preferably 80 mol% or more (e.g., about 80 to 98 mol%), more preferably 90 mol% or more, and most preferably 95 mol% or more. The polylactic acid resin may be a resin consisting of only the lactic acid component. If the proportion of the lactic acid component is too small, the biodegradability of the resin composition may be reduced.

[0049] The polylactic acid resin may be a single polylactic acid resin of the same type, or may be an alloy resin in which two or more polylactic acid resins of different types (or polymerization compositions) are combined.

[0050] The polylactic acid resin may be a resin that does not contain a 3-hydroxybutyric acid component as a polymerization component.

[0051] The melt flow rate (MFR) of the polylactic acid resin is, for example, 1 to 30 g / 10 min, preferably 2 to 20 g / 10 min, further preferably 2.5 to 15 g / 10 min, more preferably 3 to 10 g / 10 min, and most preferably 3.5 to 7 g / 10 min, under conditions of a temperature of 190° C. and a load of 2.16 kgf. If the MFR is too small, the moldability of the resin composition may decrease, whereas if it is too large, the mechanical properties of the resin composition may decrease.

[0052] The weight average molecular weight of the polylactic acid resin can be selected in the range of 1,000 to 1,000,000, and is, for example, 5,000 to 1,000,000, preferably 10,000 to 800,000, further preferably 20,000 to 700,000, more preferably 30,000 to 600,000, and most preferably 50,000 to 500,000.

[0053] In the present specification and claims, the weight average molecular weight of the polylactic acid resin can be measured by GPC in terms of standard polystyrene.

[0054] The glass transition temperature (Tg) of the polylactic acid resin is, for example, 40 to 80° C., preferably 45 to 75° C., further preferably 50 to 70° C., more preferably 55 to 65° C., and most preferably 57 to 62° C. If the glass transition temperature is too low, the heat resistance and mechanical properties of the resin composition may be reduced, and conversely, if it is too high, the biodegradability and moldability of the resin composition may be reduced. The polylactic acid resin may be crystalline.

[0055] The melting point of the polylactic acid resin is, for example, 80 to 250°C, preferably 100 to 200°C, further preferably 130 to 180°C, even more preferably 140 to 170°C, and most preferably 150 to 160°C.

[0056] In this specification and claims, the glass transition temperature and melting point of the polylactic acid resin can be measured using a differential scanning calorimeter (DSC).

[0057] The acid value of the polylactic acid resin may be, for example, 0 to 100 mgKOH / g (e.g., 0.1 to 80 mgKOH / g), preferably 0.2 to 80 mgKOH / g, more preferably 0.3 to 60 mgKOH / g, and particularly about 0.5 to 30 mgKOH / g. If the acid value is too large, there is a risk that hydrolysis may occur easily. The hydroxyl value of the polylactic acid resin can also be selected from the same range as the acid value.

[0058] The polylactic acid resin may account for 50% or more by mass in the resin composition, for example, 50 to 99% by mass, preferably 70 to 98% by mass, further preferably 80 to 97% by mass, even more preferably 90 to 96% by mass, and most preferably 92 to 95% by mass.

[0059] [Polyhydroxyalkanoic acid resin] The polyhydroxyalkanoic acid resin may be a resin classified into the polyhydroxyalkanoate (PHA) group, which is a representative biodegradable resin, together with polylactic acid (PLA). Examples of the polyhydroxyalkanoic acid resin include hydroxy C 2-10 Resins containing an alkanoic acid component as a polymerization component (excluding the polylactic acid resins) are examples of such resins. The polyhydroxyalkanoic acid resin may be a resin in which the proportion of a lactic acid component, which is a polymerization component (monomer), in all constituent monomers is less than 50 mol %, or a resin that does not contain a lactic acid component as a polymerization component.

[0060] Hydroxy C 2-10 The alkanoic acid component is hydroxy C 2-10 It may be an alkanoic acid, and the hydroxy C 2-10 It may also be a reactive derivative of an alkanoic acid.

[0061] Hydroxy C 2-10Alkanoic acids include glycolic acid, lactic acid, 3HP, 2-hydroxybutyric acid, 3HB (or BHB), 4HB, 3-hydroxy-3-methyl-butyric acid, 2-hydroxyvaleric acid (2-hydroxypentanoic acid), 3HV, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 2-hydroxy-2-methyl-valeric acid, 3-hydroxyhexanoic acid, 6-hydroxyheptanoic acid, 3-hydroxyheptanoic acid, 7-hydroxyheptanoic acid, 3-hydroxyoctanoic acid, 8-hydroxyoctanoic acid, 3-hydroxynananoic acid, 9-hydroxynananoic acid, 3-hydroxydecanoic acid, 10-hydroxydecanoic acid, and the like.

[0062] Hydroxy C 2-10 Reactive derivatives of alkanoic acids include C anhydrides, methyl esters, etc. 1-3 Examples of the acid halide include an alkyl ester, an acid halide such as an acid chloride, and a corresponding lactone.

[0063] These hydroxy C 2-10 The alkanoic acid components can be used alone or in combination of two or more.

[0064] These hydroxy C 2-10 Among the alkanoic acid components, hydroxy C 3-10 Alkanoic acid moieties are preferred, and hydroxy C 4-10 Alkanoic acid moieties are more preferred, and hydroxy C 4-8 Alkanoic acid moieties are more preferred, and hydroxy C 4-6 Alkanoic acid moieties are most preferred. 4-6 Among the alkanoic acid components, 3-hydroxy C 4-6 An alkanoic acid moiety is preferred, a 3-hydroxybutyric acid moiety and / or a 3-hydroxyvaleric acid moiety is more preferred, and a 3-hydroxybutyric acid moiety is even more preferred.

[0065] 3-Hydroxy C 4-6The alkanoic acid component may be an optical isomer (R or S form), or may be an S form or racemic form, but from the standpoint of biodegradability, it is preferable that the component contains at least the R form [particularly, an (R)-3-hydroxybutyric acid component or an (R)3HB component].

[0066] 3-Hydroxy C 4-6 The proportion of R-isomers in the alkanoic acid component, particularly the optical purity (enantiomer or optical isomer excess), is, for example, 50% ee or more (e.g., 80% ee or more), preferably 90% ee or more (e.g., 95 to 100% ee), and more preferably 98 to 100% ee (e.g., 99 to 100% ee, particularly substantially 100% ee). If the optical purity is too low, there is a risk of reduced biodegradability.

[0067] 3-Hydroxy C 4-6 The mass proportion of the R-isomer in the alkanoic acid component is preferably 10% by mass or more, further preferably 50% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass.

[0068] Hydroxy C 2-10 Reactive derivatives of alkanoic acid components include C anhydrides, methyl esters, etc. 1-3 Examples of the acid halide include an alkyl ester, an acid halide such as an acid chloride, and a corresponding lactone.

[0069] Hydroxy C 4-6 Alkanoic acid components (especially hydroxy C 4-5 The ratio of hydroxy C 2-10 The hydroxyl group may account for 50 mol % or more of the alkanoic acid component, preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, and most preferably 100 mol %. 4-6 If the proportion of the alkanoic acid component is too low, there is a risk that flexibility and biodegradability will decrease.

[0070] Hydroxy C 2-10The proportion of the alkanoic acid component may be the maximum proportion in all the constituent monomers, and may be, for example, 50 mol % or more of all the constituent monomers, preferably 70 mol % or more, further preferably 80 mol % or more, even more preferably 90 mol % or more, and most preferably 100 mol %. 2-10 If the proportion of the alkanoic acid component is too low, the flexibility of the resin composition may decrease.

[0071] Polyhydroxyalkanoic acid resins contain hydroxy C as a polymerization component. 2-10 In addition to the alkanoic acid component, hydroxy C 2-10 The copolymer may further contain a copolymerizable component that can be copolymerized with the alkanoic acid component. The copolymerizable component may be a diol, a dicarboxylic acid component, a hydroxy C 2-10 and hydroxycarboxylic acid components other than alkanoic acid components.

[0072] The diol is not particularly limited, and can be selected from the diols exemplified in the section on polylactic acid resins, including preferred embodiments.

[0073] The dicarboxylic acid component is not particularly limited, and can be selected from the dicarboxylic acid components exemplified in the section on polylactic acid resins, including preferred embodiments.

[0074] Examples of the hydroxycarboxylic acid component include the hydroxyalicyclic carboxylic acid components and hydroxyaromatic carboxylic acid components exemplified in the section on the polylactic acid resin.

[0075] These copolymerization components can be used alone or in combination of two or more. The proportion of these copolymerization components in the total constituent monomers may be less than 50 mol%, preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 10 mol% or less, and most preferably 1 mol% or less.

[0076] Polyhydroxyalkanoic acid resin is a type of hydroxy C 4-6 Polyhydroxy C with alkanoic acid as the main polymerization component 4-6It may be an alkanoic acid resin, and hydroxy C 4-5 Polyhydroxy C with alkanoic acid as the main polymerization component 4-5 Alkanoic acid resins are preferred. The polyhydroxyalkanoic acid resin may also be a poly3-hydroxybutyric acid resin (poly3HB resin) containing a 3-hydroxybutyric acid component (3HB component) as a main polymerization component, with poly(R)3HB resin being preferred.

[0077] Preferred Polyhydroxy C 4-6 Examples of the alkanoic acid resin include a homopolymer of an (R)-3-hydroxybutyric acid component, and a copolymer of an (R)-3-hydroxybutyric acid component and a copolymer component.

[0078] Examples of the copolymerizable component copolymerizable with the (R)-3-hydroxybutyric acid component include hydroxy C components such as 3HP components, 3HB components, 4HB components, 3HV components, and 3-hydroxyhexanoic acid components. 2-10 Alkanoic acid components and the like. These copolymerization components can be used alone or in combination of two or more. Among these copolymerization components, 3-hydroxy C components such as 4HB components, (R)3HV components, and (R)-3-hydroxyhexanoic acid components are preferred because of their excellent biodegradability. 4-8 Alkanoic acid components are preferred, and 3-hydroxy C such as (R)3HV component and (R)-3-hydroxyhexanoic acid component are preferred because they can improve the flexibility of the resin composition. 5-7 Alkanoic acid components are particularly preferred.

[0079] In a copolymer of an (R)-3-hydroxybutyric acid component and a copolymerization component, the molar ratio of both components, (R)-3-hydroxybutyric acid component / copolymerization component, is 99.99 / 0.01 to 50 / 50, preferably 99.95 / 0.05 to 70 / 30, further preferably 99.9 / 0.1 to 90 / 10, more preferably 99.8 / 0.2 to 95 / 5, and most preferably 99.7 / 0.3 to 97 / 3.

[0080] The polyhydroxyalkanoic acid resin may be a single polyhydroxyalkanoic acid resin of the same type, or may be an alloy resin in which two or more poly(3-hydroxybutyric acid) resins of different types (or polymerization compositions) are combined.

[0081] The weight average molecular weight of the polyhydroxyalkanoic acid resin can be selected from the range of 1,000 to 3,000,000, and is, for example, 10,000 to 2,500,000, preferably 50,000 to 2,000,000, further preferably 100,000 to 1,500,000, more preferably 200,000 to 1,000,000, and most preferably 300,000 to 800,000.

[0082] In the present specification and claims, the weight average molecular weight of the polyhydroxyalkanoic acid resin can be measured by GPC in terms of standard polystyrene.

[0083] The polyhydroxyalkanoic acid resin may be crystalline.

[0084] Polyhydroxyalkanoic acid resin (especially polyhydroxy C 4-6 The melting point of the alkanoic acid resin is, for example, 60 to 250°C, preferably 70 to 200°C, further preferably 80 to 180°C, even more preferably 90 to 170°C, and most preferably 100 to 160°C.

[0085] In this specification and claims, the melting point of the polyhydroxyalkanoic acid resin can be measured using a differential scanning calorimeter (DSC).

[0086] Polyhydroxyalkanoic acid resin (especially polyhydroxy C 4-6The proportion of the polyhydroxyalkanoic acid resin can be selected from the range of about 2 to 50 parts by mass relative to 100 parts by mass of the polylactic acid resin, and is, for example, 3 to 30 parts by mass (particularly 4 to 25 parts by mass), preferably 4.5 to 20 parts by mass, further preferably 5 to 15 parts by mass, more preferably 5.5 to 10 parts by mass, and most preferably 6 to 9 parts by mass. If the proportion of the polyhydroxyalkanoic acid resin is too low, the flexibility of the resin composition may decrease, whereas if it is too high, the transparency, flexibility (elongation at break), and tensile modulus may decrease.

[0087] [Other ingredients] The resin composition of the present invention may further contain other components. The other components may be other resins or conventional additives that are blended into resins.

[0088] Examples of the other resins include other aliphatic polyester resins, aliphatic polyamide resins, cellulose-based resins, polyvinyl alcohol-based resins, etc. These other resins may be used alone or in combination of two or more.

[0089] Examples of commonly used additives include antiblocking agents, slip agents (or anti-scratch agents), stabilizers (antiaging agents, antioxidants, antiozonants, UV absorbers, light stabilizers, heat stabilizers, etc.), flame retardants, compatibilizers, softeners, lubricants, antistatic agents, crystal nucleating agents, colorants, preservatives, antifungal agents, etc. These additives may be used alone or in combination of two or more.

[0090] The total proportion of the other components can be selected from the range of about 0.1 to 100 parts by mass, for example, 0.5 to 50 parts by mass, preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, per 100 parts by mass of the polylactic acid resin.

[0091] The resin composition of the present invention has excellent flexibility even without a plasticizer, so the proportion of the plasticizer may be small. The proportion of the plasticizer may be less than 5 parts by mass, preferably 3 parts by mass or less, more preferably 1 part by mass or less, and more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the polylactic acid resin. The resin composition of the present invention may be substantially free of a plasticizer, and preferably does not contain a plasticizer.

[0092] [Characteristics and preparation method of resin composition] The resin composition of the present invention has excellent flexibility. The elongation at break of the resin composition of the present invention (test speed: 10 mm / min) may be 50% or more (particularly 100% or more), for example, 150 to 1000%, preferably 200 to 800%, further preferably 250 to 500%, more preferably 300 to 450%, and most preferably 350 to 400%. If the elongation at break is too low, the flexibility of the resin composition may decrease.

[0093] In this specification and claims, the elongation at break (elongation at break or elongation at break) of a resin composition can be measured in accordance with JIS K 7161, and in detail, can be measured by the method described in the examples below.

[0094] The tensile modulus of the resin composition of the present invention (test speed: 10 mm / min) may be 2000 MPa or less (particularly 1500 MPa or less), for example, 500 to 2000 MPa, preferably 1000 to 1500 MPa, further preferably 1200 to 1450 MPa, and further preferably 1300 to 1400 MPa. If the tensile modulus is too high, the flexibility of the resin composition may decrease.

[0095] In the present specification and claims, the tensile modulus of elasticity of the resin composition can be measured in accordance with JIS K 7161, and in detail, can be measured by the method described in the examples described later.

[0096] The resin composition of the present invention also has excellent mechanical properties. The Izod impact strength (notched) of the resin composition of the present invention is 1 kJ / m 2or more, for example, 1 to 30 kJ / m 2 , preferably 1.5 to 10 kJ / m 2 , more preferably 2 to 5 kJ / m 2 , more preferably 2.3 to 4 kJ / m 2 , and most preferably 2.5 to 3.5 kJ / m 2 If the impact strength is too low, there is a risk of the mechanical properties being reduced.

[0097] In the present specification and claims, the Izod impact strength of the resin composition can be measured in accordance with ISO 180, and more specifically, by the method described in the examples below.

[0098] The resin composition of the present invention has excellent melt fluidity and high moldability. The MFR (melt flow rate or melt flow index (MFI)) of the resin composition of the present invention (temperature: 190°C, load: 2.16 kgf) may be 1 g / 10 min or more, for example, 1 to 30 g / 10 min, preferably 3 to 20 g / 10 min, further preferably 5 to 10 g / 10 min, more preferably 6 to 9 g / 10 min, and most preferably 7 to 8 g / 10 min. If the MFR is too small, there is a risk of reduced moldability.

[0099] In the present specification and claims, the MFR of a resin composition can be measured in accordance with ISO 1133, and more specifically, by the method described in the examples below.

[0100] The glass transition temperature (Tg) of the resin composition of the present invention can be selected, for example, within the range of about 10 to 150°C, and is, for example, 20 to 100°C, preferably 30 to 80°C, further preferably 40 to 75°C, more preferably 50 to 70°C, and most preferably 55 to 65°C.

[0101] In this specification and claims, the glass transition temperature of the resin composition can be measured using a differential scanning calorimeter (DSC), and in detail, can be measured by the method described in the examples below.

[0102] The resin composition of the present invention can be prepared by mixing a polylactic acid resin, a polyhydroxyalkanoic acid resin, and other components as necessary by a conventional method such as dry mixing or melt kneading, and the resin composition may be in the form of pellets, etc. When melt kneading, the kneading temperature is, for example, 100 to 250°C, preferably 130 to 230°C, more preferably 150 to 220°C, more preferably 160 to 200°C, and most preferably 170 to 190°C. As the method for melt kneading, a conventional method can be used, and for example, a twin-screw extrusion kneader may be used.

[0103] [Molded body] The molded article of the present invention may be formed from the resin composition. The shape of the molded article of the present invention is not particularly limited and can be selected according to the application, and may be a one-dimensional structure such as a line or thread; a two-dimensional structure such as a film, sheet, or plate; or a three-dimensional structure such as a block, rod, tube, or hollow.

[0104] The molded article of the present invention can be produced by molding the resin composition by a conventional molding method, such as compression molding, injection molding, injection compression molding, extrusion molding, transfer molding, blow molding, pressure molding, and casting molding.

[0105] When the molded article of the present invention is a film-like or sheet-like two-dimensional structure, the molded article of the present invention can be produced by forming the resin composition into a film (or molding it) using a conventional film-forming method, such as an inflation molding method, a casting method (solvent casting method), a melt extrusion method, or a calendar method.

[0106] When the molded article of the present invention is produced by injection molding, the cylinder temperature is, for example, 130 to 250°C, preferably 150 to 230°C, further preferably 180 to 210°C, more preferably 185 to 205°C, and most preferably 190 to 200°C. EXAMPLES

[0107] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The raw materials used are as follows, and the properties and evaluation of the obtained resin composition and test pieces were measured and evaluated as follows.

[0108] [Ingredients used] PLA (polylactic acid): Manufactured by Anhui Fengyuan Group Co., Ltd.; FY804, melting point 150-160℃, L content 95.5%, D content 4.5%, MFR (temperature 190℃, load 2.16kgf) 4g / 10 minutes, glass transition temperature 60℃ PHB (Poly(R)-hydroxybutyric acid): Ningbo Tainan Biologic Material Co., Ltd.; ENMAT Y3000, glass transition temperature 4℃ PHBV ((R)-hydroxybutyric acid-(R)-hydroxyvaleric acid copolymer): manufactured by Ningbo Tainan Biologic Material Co., Ltd.; ENMAT Y1000P, glass transition temperature -1℃

[0109] [Glass transition temperature] The glass transition temperature (Tg) of the resulting resin composition was measured using a differential scanning calorimeter ("DSC214 Polymer" manufactured by Netzsch Japan KK).

[0110] [Elongation at break and tensile modulus] The resin composition was measured for breaking elongation and tensile modulus using a small tabletop tester (Shimadzu Corporation, "EZ-Graph") in accordance with JIS K 7161. The test conditions were a crosshead speed of 10 mm / min, a test piece length of 75 mm, a width of 10 mm, and a thickness of 2 mm. A load cell of 100 N was used.

[0111] [IZOD impact strength (notched)] The Izod impact strength of the resin composition was measured in accordance with ISO 180 using an impact tester (Impact Tester manufactured by Yasuda Seiki Seisakusho Co., Ltd.). The test conditions were a lift angle of 150° and a notched test piece. The length of the test piece was 54 mm, the width was 12 mm, and the thickness was 3 mm.

[0112] [MFR] The resin composition was measured in accordance with ISO 1133 under conditions of a holding time of 5 minutes, a temperature of 190° C., and a test load of 2.16 kgf.

[0113] [Transparency] For each resin composition, a test piece having a thickness of 2 mm was prepared, and the transparency of the test piece was visually observed and evaluated according to the following criteria.

[0114] 1...Almost completely transparent 2…Slightly cloudy 3 - Cloudy but clear 4…Highly turbid 5...Completely opaque

[0115] Example 1 A resin composition (PHB content: 8% by mass) was prepared by mixing 276 g of PLA and 24 g of PHB, melt-kneading the mixture at 180°C using a twin-screw extruder, and pelletizing the mixture. The resulting resin pellets were injection-molded at 195°C, and the mold releasability was good.

[0116] Example 2 A resin composition (PHB content: 14% by mass) was prepared and a test piece was manufactured in the same manner as in Example 1, except that 258 g of PLA and 42 g of PHB were used. The releasability was good.

[0117] Example 3 A resin composition (PHB content: 20% by mass) was prepared and a test piece was manufactured in the same manner as in Example 1, except that 240 g of PLA and 60 g of PHB were used. The releasability was good.

[0118] Example 4 A resin composition (PHBV content: 8 mass%) was prepared and a test piece was manufactured in the same manner as in Example 1, except that 276 g of PLA and 24 g of PHBV were used. The releasability was good.

[0119] Example 5 A resin composition (PHBV content: 14% by mass) was prepared and a test piece was manufactured in the same manner as in Example 1, except that 258 g of PLA and 42 g of PHBV were used. The releasability was good.

[0120] Example 6 A resin composition (PHBV content: 20% by mass) was prepared and a test piece was manufactured in the same manner as in Example 1, except that 240 g of PLA and 60 g of PHBV were used. The releasability was good.

[0121] Comparative Example 1 Using only PLA, a twin-screw extruder was used to melt-knead at 165°C and pelletize the resin. The resulting resin pellets were injection-molded at 195°C, and the mold release properties were good.

[0122] Comparative Example 2 A resin composition (PHB content: 1% by mass) was prepared in the same manner as in Example 1 except that 297 g of PLA and 3 g of PHB were used, and a test piece was manufactured.

[0123] Comparative Example 3 A resin composition (PHBV content: 1% by mass) was prepared in the same manner as in Example 1 except that 297 g of PLA and 3 g of PHBV were used, and a test piece was manufactured.

[0124] Table 1 shows the evaluation results of the resin compositions and the test pieces of the injection-molded products obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

[0125] [Table 1]

[0126] As is clear from the results in Table 1, the test pieces of Examples 1 to 6 had good breaking elongation. In particular, the test pieces obtained in Examples 1 and 4 had high breaking elongation and excellent transparency.

[0127] In contrast, the breaking elongation of the test pieces obtained in Comparative Examples 1 to 3 was small, and in the test pieces of Comparative Examples 1 and 3, it was very small. [Industrial Applicability]

[0128] The resin composition of the present invention has high biodegradability and can be used in various fields, such as paints, antistatic agents, inks, adhesives, pressure sensitive adhesives, electric and electronic materials (e.g., carrier transport agents, luminescent bodies, organic photoreceptors, etc.), electric and electronic parts or devices (e.g., optical lenses, optical films, optical disks, inkjet printers, digital paper, organic semiconductor lasers, dye-sensitized solar cells, etc.), mechanical parts or devices (e.g., automobiles, aviation and space materials, sensors, etc.). In particular, because of its high mechanical properties, it can be easily molded by extrusion molding, injection molding, etc., and can be suitably used for molded members in various fields (e.g., molded bodies such as casings and housings), containers (containers for food, daily necessities, electrical and electronic devices and parts, etc.), packaging materials such as films and sheets, and garbage bags. In addition, the problem of microplastics (especially microplastics in the ocean), which has become a new problem in recent years, can also be solved by taking advantage of its high biodegradability.

Claims

1. A resin composition comprising a polylactic acid resin and a polyhydroxyalkanoic acid resin, the proportion of the polyhydroxyalkanoic acid resin being 2 to 50 parts by mass per 100 parts by mass of the polylactic acid resin.

2. The polyhydroxyalkanoic acid resin is hydroxy C ４－１０ The resin composition according to claim 1, which comprises an alkanoic acid component as a polymerization component.

3. The polyhydroxyalkanoic acid resin is hydroxy C ４－６ 3. The resin composition according to claim 1, which contains an alkanoic acid component as a polymerization component.

4. 3. The resin composition according to claim 1, wherein the polyhydroxyalkanoic acid resin contains at least one component selected from the group consisting of an (R)-3-hydroxybutyric acid component and an (R)-3-hydroxyvaleric acid component as a polymerization component.

5. 3. The resin composition according to claim 1, wherein the polyhydroxyalkanoic acid resin contains an (R)-3-hydroxybutyric acid component as a polymerization component.

6. 3. The resin composition according to claim 1, wherein the proportion of said polyhydroxyalkanoic acid resin is 3 to 30 parts by mass per 100 parts by mass of said polylactic acid resin.

7. 3. The resin composition according to claim 1, which has a melt flow rate of 1 to 30 g / 10 min at a temperature of 190° C. and a load of 2.16 kgf.

8. 3. The resin composition according to claim 1, which is substantially free of a plasticizer.

9. A molded article formed from the resin composition according to claim 1 or 2.

10. The molded article according to claim 9, which is a film or sheet.

11. A method for improving the flexibility of a resin composition comprising a polylactic acid-based resin and a polyhydroxyalkanoic acid-based resin, by adjusting the proportion of the polyhydroxyalkanoic acid to 2 to 50 parts by mass per 100 parts by mass of the polylactic acid-based resin.

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