Polylactic acid resin composition for injection blow molding, method for producing polylactic acid resin composition, injection blow molded article, and method for producing injection blow molded article

Abstract

The polylactic acid resin composition for injection blow molding, which is obtained by modifying a polylactic acid resin with an organic peroxide, has a melt tension at 190 DEG C of from 20.0 cN to 85.0 cN (inclusive). The crystallization temperature during the cooling process using a differential scanning calorimeter at 5 DEG C / min is 120 DEG C or less, or there is no crystallization peak.

Description

Technical Field

[0001] The present invention relates to a polylactic acid resin composition suitable for injection blow molding and a manufacturing technique thereof. More specifically, it relates to a manufacturing technique for controlling melt tension and crystallization rate. By this manufacturing technique, a polylactic acid resin composition with excellent processability can be provided.

[0002] [Explanation of Units]

[0003] The meanings of the units used in this specification are as described below.

[0004] In the unit of time, h is hours, min is minutes, and s is seconds.

[0005] In the unit of quantity, L is liters.

[0006] In the unit of force, N is Newton.

[0007] In the unit of concentration, N is normal concentration.

[0008] In the unit of speed, rpm is revolutions per minute.

[0009] In the unit of viscosity, Pa·s is Pascal seconds.

[0010] Gram equivalent is denoted as g / eq. Background Art

[0011] In recent years, with the improvement of environmental awareness, there has been an expectation to use raw materials that are easily decomposed in nature. That is, research is being conducted on using aliphatic polyester resins such as polylactic acid resins, which are easily decomposed in nature, as raw materials for various products.

[0012] However, polylactic acid resins generally have the disadvantages of low melt tension and poor processability.

[0013] Various improvement techniques for compensating for this disadvantage have been proposed (for example, refer to Patent Document 1, Patent Document 2, and Patent Document 3).

[0014] That is, Patent Document 1 discloses a technique for modifying a polylactic acid resin with a specific organic peroxide. By this technique, a polylactic acid resin that suppresses the problem of odor generation and has excellent melt tension can be obtained.

[0015] In addition, Patent Document 2 discloses a technique for modifying a polylactic acid resin with an organic peroxide. By this technique, a polylactic acid resin composition for injection molding having rheological properties suitable for injection molding and capable of improving productivity in injection molding can be obtained.

[0016] In addition, Patent Document 3 discloses a technique for modifying polylactic acid resin with an organic peroxide. Through this technique, a lactic acid-based resin composition having excellent processability and physical properties in addition to the inherent biodegradability, and a molded article formed therefrom are obtained.

[0017] The inventors of the present invention have conducted research on manufacturing injection blow molded articles such as containers using various resins. There is no problem with general-purpose resins different from polylactic acid resin, and high-quality injection blow molded articles are obtained. In contrast, the moldability of polylactic acid resin is poor, and the productivity is reduced. After detailed investigation, it was found that crystallization occurs during injection blow molding, and this crystallization hinders plastic deformation.

[0018] As described above, Patent Documents 1 to 3 provide techniques for obtaining a polylactic acid resin having excellent foaming properties, injection moldability, etc. by modifying polylactic acid and improving melt tension and rheological properties.

[0019] However, in Patent Documents 1 to 3, the crystallization rate has not been sufficiently studied. As a result, the productivity cannot be improved in the prior art.

[0020] In the process of demanding productivity improvement, a polylactic acid resin composition having excellent injection blow moldability and a manufacturing technique thereof are desired.

[0021] Prior Art Documents

[0022] Patent Documents

[0023] Patent Document 1: Japanese Patent Laid-Open No. 2019-183140

[0024] Patent Document 2: Japanese Patent Laid-Open No. 2007-262222

[0025] Patent Document 3: Japanese Patent Laid-Open No. 2003-171544 Summary of the Invention

[0026] Problems to be Solved by the Invention

[0027] The problem to be solved by the present invention is to provide a polylactic acid resin composition having excellent injection blow moldability and a manufacturing technique thereof.

[0028] Means for Solving the Problems

[0029] The inventors of the present invention consider as follows.

[0030] In the prior art, crystallization occurs during injection blow molding, resulting in reduced productivity. If crystallization does not occur during injection blow molding, an increase in productivity can be expected. If complete non-crystallization cannot be achieved, then by allowing crystallization at the end of injection blow molding, the reduction in moldability can be suppressed, and an increase in productivity can be expected.

[0031] Based on these ideas, poly(lactic acid) resin was modified with an organic peroxide, and various poly(lactic acid) resin compositions obtained were evaluated. It was found that if the crystallization temperature during the temperature decrease process at 5 °C / min measured using a differential scanning calorimeter is 120 °C or lower, an increase in productivity can be predicted.

[0032] Among them, in injection blow molding, the parison is expanded by a fluid (such as compressed air). When the melt tension of the parison at 190 °C is less than 20.0 cN, the melt tension is too small, and sometimes the molded body breaks. In addition, when the melt tension of the parison at 190 °C exceeds 85.0 cN, the parison is difficult to elongate, and sometimes the molded body is cut.

[0033] It can be seen that if the melt tension at 190 °C is 20.0 cN or more and 85.0 cN or less, breakage and cutting can be suppressed.

[0034] Based on the above insights, the present invention has the following solutions.

[0035] [1]: A poly(lactic acid) resin composition for injection blow molding, which is a poly(lactic acid) resin composition for injection blow molding obtained by modifying a poly(lactic acid) resin with an organic peroxide, wherein

[0036] the melt tension at 190 °C is 20.0 cN or more and 85.0 cN or less,

[0037] the crystallization temperature during the temperature decrease process at 5 °C / min using a differential scanning calorimeter is 120 °C or lower or there is no crystallization peak.

[0038] [2]: The poly(lactic acid) resin composition for injection blow molding according to the above [1], wherein the melt mass flow rate of the poly(lactic acid) resin composition at a temperature of 190 °C and a nominal load of 21.18 N is 0.1 g / 10 min or more and 20.0 g / 10 min or less.

[0039] [3]: The poly(lactic acid) resin composition for injection blow molding according to the above [1], wherein the melt mass flow rate of the poly(lactic acid) resin composition at a temperature of 190 °C and a nominal load of 21.18 N is 0.1 g / 10 min or more and 10.0 g / 10 min or less.

[0040] [4]: The poly(lactic acid) resin composition for injection blow molding according to any one of the above [1] to [3], wherein the proportion of the D-form in the total of the D-form and the L-form in the poly(lactic acid) resin composition is 3.0 mol% or more and 20.0 mol% or less.

[0041] [5]: The polylactic acid resin composition for injection blow molding according to any one of [1] to [3] above, wherein the proportion of the D-form in the total of the D-form and the L-form in the polylactic acid resin composition is 3.3 mol% or more and 18.0 mol% or less.

[0042] [6]: The polylactic acid resin composition for injection blow molding according to any one of [1] to [3] above, wherein the proportion of the D-form in the total of the D-form and the L-form in the polylactic acid resin composition is 3.5 mol% or more and 15.0 mol% or less.

[0043] [7]: The polylactic acid resin composition for injection blow molding according to any one of [1] to [6] above, wherein the organic peroxide is used in a proportion of 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100 parts by mass of the above polylactic acid resin for modification.

[0044] [8]: A method for manufacturing a polylactic acid resin composition, which is a method for manufacturing the polylactic acid resin composition described in any one of [1] to [3] above, wherein, with respect to 100 parts by mass of a polylactic acid resin in which the proportion of the D-form in the total of the D-form and the L-form is 3.0 mol% or more and 20.0 mol% or less, an organic peroxide is melt-kneaded in a proportion of 0.10 parts by mass or more and 3.00 parts by mass or less to produce it.

[0045] [9]: A method for manufacturing a polylactic acid resin composition, which is a method for manufacturing the polylactic acid resin composition described in any one of [1] to [3] above, wherein, with respect to 100 parts by mass of a polylactic acid resin in which the proportion of the D-form in the total of the D-form and the L-form is 3.3 mol% or more and 18.0 mol% or less, an organic peroxide is melt-kneaded in a proportion of 0.10 parts by mass or more and 3.00 parts by mass or less to produce it.

[0046]

[10] : A method for manufacturing a polylactic acid resin composition, which is a method for manufacturing the polylactic acid resin composition described in any one of [1] to [3] above, wherein, with respect to 100 parts by mass of a polylactic acid resin in which the proportion of the D-form in the total of the D-form and the L-form is 3.5 mol% or more and 15.0 mol% or less, an organic peroxide is melt-kneaded in a proportion of 0.10 parts by mass or more and 3.00 parts by mass or less to produce it.

[0047]

[11] : An injection blow molded article obtained by injection blow molding the polylactic acid resin composition described in any one of [1] to [7] above.

[0048]

[12] : A method for manufacturing an injection blow molded article obtained by injection blow molding the polylactic acid resin composition described in any one of the above [1] to [7].

[0049]

[13] : A method for manufacturing an injection blow molded article, which is the method for manufacturing an injection blow molded article described in the above

[12] , comprising:

[0050] A preparation step of preparing an injection blow molding apparatus, the injection blow molding apparatus having an injection device for injecting the molten polylactic acid resin composition, a preform mold for forming a preform, and a blow mold for blow molding;

[0051] A preform forming step of obtaining the preform by injecting the polylactic acid resin composition into the preform mold through the injection device;

[0052] A transfer step of transferring the obtained preform from the preform mold to the blow mold; and

[0053] A blow molding step of obtaining an injection blow molded article by blow molding the transferred preform with the blow mold.

[0054] Effects of the Invention

[0055] According to the present invention, a polylactic acid resin composition excellent in injection blow moldability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a diagram for explaining the manufacturing method of the polylactic acid resin composition of the present invention.

[0057] Figure 2 It is a diagram for explaining the basic configuration of an injection blow molding apparatus.

[0058] Figure 3 It is a diagram for explaining the basic configuration of a core.

[0059] Figure 4 It is a diagram for explaining the heating curve for crystallization temperature and the heating curve for crystallization time.

[0060] Figure 5 It is a DSC curve diagram of the crystallization temperature of Example 1.

[0061] Figure 6 It is a DSC curve diagram of the crystallization time of Comparative Example 1.

[0062] Figure 7 (a) It is a diagram for explaining the morphology at the initial stage of blow molding, Figure 7 (b) It is a diagram for explaining the morphology at the middle stage of blow molding, Figure 7 (c) It is a diagram for explaining the morphology at the final stage of blow molding. Detailed implementation manners

[0063] Hereinafter, implementation manners of the present invention will be described based on the accompanying drawings.

[0064] [Polylactic acid resin]

[0065] The polylactic acid resin of this implementation manner can be a homopolymer of lactic acid or a copolymer of lactic acid and other monomers.

[0066] As other monomers in the above copolymers, aliphatic hydroxycarboxylic acids, aliphatic polyols, aliphatic polycarboxylic acids, etc. other than lactic acid can be cited.

[0067] The above monomers can be, for example, polyfunctional polysaccharides, etc.

[0068] In the polylactic acid resin of this implementation manner, the proportion of the D-form in the total of the D-form and the L-form is preferably 3.0 mol% or more.

[0069] The proportion of the above D-form is more preferably 3.3 mol% or more, and particularly preferably 3.5 mol% or more.

[0070] The proportion of the above D-form is preferably 20.0 mol% or less, more preferably 18.0 mol% or less, and particularly preferably 15.0 mol% or less.

[0071] When the proportion of the D-form in the polylactic acid resin of this implementation manner is less than 3.0 mol%, the crystallization rate becomes fast, crystallization occurs during injection blow molding, and the moldability decreases.

[0072] In addition, when the proportion of the D-form in the polylactic acid resin of this implementation manner exceeds 20.0 mol%, the yellowing of the resin is significant and the appearance deteriorates.

[0073] As the aliphatic polycarboxylic acid constituting the above copolymer, for example, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, dodecanedioic acid can be cited.

[0074] The aliphatic polycarboxylic acid can be an acid anhydride.

[0075] As the above aliphatic polyol, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, tetramethylene glycol, 1,4-cyclohexanedimethanol, etc. can be cited.

[0076] As the hydroxycarboxylic acid other than lactic acid constituting the above copolymer, for example, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxypentanoic acid, 5-hydroxypentanoic acid, 6-hydroxyhexanoic acid, etc. can be cited.

[0077] Examples of the multifunctional polysaccharides described above include cellulose, nitrocellulose, methylcellulose, ethylcellulose, celluloid, viscose rayon, regenerated cellulose, cellophane, cuprammonium fiber, cuprammonium rayon, cuprophane, Bemberg, hemicellulose, starch, acropectin, dextrin, dextran, glycogen, pectin, chitin, chitosan, gum arabic, guar gum, locust bean gum, acacia gum, etc.

[0078] The polylactic acid resin in the present embodiment can be blended with other resins within the range that does not impair its performance.

[0079] [Modification]

[0080] The above-mentioned polylactic acid resin (polylactic acid resin having melting characteristics) can be obtained by modifying a commercially available polylactic acid resin.

[0081] In the above modification, a crosslinked structure or a long-chain branched structure can be introduced into the molecular structure of the polylactic acid resin, or the polylactic acid resin can be made to have a higher molecular weight.

[0082] To increase the molecular weight of the polylactic acid resin, chain extenders such as carbodiimide can be used.

[0083] In addition, the modification based on the chain extender can be carried out using compounds having one or more functional groups capable of undergoing a condensation reaction with hydroxyl groups or carboxyl groups present in the molecular structure of the polylactic acid resin, such as acrylic organic compounds, epoxy organic compounds, and isocyanate organic compounds.

[0084] That is, the above modification can be carried out by a method of binding acrylic organic compounds, epoxy organic compounds, isocyanate organic compounds, etc. to the polylactic acid resin through a reaction.

[0085] The modification of the polylactic acid resin with crosslinking or long-chain branching can be carried out, for example, by a method of reacting the polylactic acid resins with each other using a radical initiator.

[0086] Among the above modification methods, in terms of being able to suppress the inclusion of other components, it is preferable to react the polylactic acid resins with each other using a radical initiator.

[0087] It should be noted that when a suitable radical initiator reacts with the polylactic acid resin, free radicals are generated in the polylactic acid resin. The free radicals generated in the polylactic acid resin react with each other in the extruder to form crosslinking points (branching points) of the polylactic acid resin and are stabilized.

[0088] The polylactic acid resin can have a crosslinked structure, a long-chain branched structure in the molecular structure of the polylactic acid resin through such modification, or the polylactic acid resin can be made to have a high molecular weight.

[0089] Examples of the radical initiator used for the modification of the polylactic acid resin include organic peroxides, azo compounds, halogen molecules, and the like.

[0090] Among them, organic peroxides are preferred.

[0091] [Organic peroxide]

[0092] Examples of the organic peroxide used in the present embodiment include peroxide esters, hydroperoxides, dialkyl peroxides, diacyl peroxides, diperoxycarbonates, peroxoketals, and ketone peroxides.

[0093] Examples of the peroxide ester include tert-butylperoxy 2-ethylhexyl carbonate, tert-hexylperoxy isopropyl monocarbonate, tert-hexylperoxy benzoate, tert-butylperoxy benzoate, tert-butylperoxy laurate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxy acetate, 2,5-dimethyl 2,5-bis(benzoylperoxy)hexane, and tert-butylperoxy isopropyl monocarbonate.

[0094] Examples of the hydroperoxide include p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, and tert-butyl hydroperoxide.

[0095] Examples of the dialkyl peroxide include diisopropylbenzene peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)-hexyne-3.

[0096] Examples of the diacyl peroxide include dibenzoyl peroxide, bis(4-methylbenzoyl) peroxide, and bis(3-methylbenzoyl) peroxide.

[0097] Examples of the diperoxycarbonate include bis(2-ethylhexyl) diperoxycarbonate, diisopropyl diperoxycarbonate.

[0098] Examples of the peroxoketal include 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-tert-butylperoxycyclohexane, 2,2-bis(tert-butylperoxy)-butane, n-butyl 4,4-di-(tert-butylperoxy)valerate, and 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane.

[0099] As the above-mentioned ketone peroxides, examples thereof include methyl ethyl ketone peroxide, acetylacetone peroxide, etc.

[0100] (Amount of preferred organic peroxide)

[0101] The above-mentioned organic peroxide also depends on the molecular weight of the polylactic acid resin, etc., but usually is used in a proportion of 0.10 parts by mass or more relative to 100 parts by mass of the polylactic acid resin to be modified.

[0102] The usage amount of the organic peroxide is preferably 0.20 parts by mass or more, and particularly preferably 0.30 parts by mass or more.

[0103] In addition, the organic peroxide also depends on the molecular weight of the polylactic acid resin, etc., but usually is used in a proportion of 3.00 parts by mass or less relative to 100 parts by mass of the polylactic acid resin to be modified.

[0104] The usage amount of the organic peroxide is preferably 2.50 parts by mass or less, more preferably 2.00 parts by mass or less, and particularly preferably 1.50 parts by mass or less.

[0105] By modifying the polylactic acid resin by using the organic peroxide in such a proportion, the modified polylactic acid resin can be made suitable for injection blow molding.

[0106] By making the usage amount of the above-mentioned organic peroxide 0.10 parts by mass or more, the effect brought by the modification of the polylactic acid resin can be more reliably exerted.

[0107] In addition, by making the usage amount of the organic peroxide 3.00 parts by mass or less, the mixing of gels in the modified polylactic acid resin can be inhibited.

[0108] [Crosslinking aid]

[0109] As a method for modifying the polylactic acid resin, a crosslinking aid can also be used together with the organic peroxide. As the crosslinking aid, divinylbenzene, diallylbenzene, divinylnaphthalene, divinylphenyl, divinylcarbazole, divinylpyridine, etc. can be cited.

[0110] The crosslinking aid can be polyfunctional acrylic compounds such as ethylene glycol diacrylate, butanediol diacrylate, triethylene glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol tetraacrylate, etc.; polyfunctional methacrylic compounds such as ethylene glycol dimethacrylate, butanediol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, etc.

[0111] Crosslinking aids may include polyvinyl esters, polyallyl esters, polyacryloyloxyalkyl esters, and polymethacryloyloxyalkyl esters of aliphatic and aromatic polycarboxylic acids such as divinyl phthalate, diallyl phthalate, diallyl maleate, and bisacryloyloxyethyl terephthalate; polyvinyl ethers and polyallyl ethers of aliphatic and aromatic polyols such as diethylene glycol divinyl ether, hydroquinone divinyl ether, and bisphenol A diallyl ether; allyl esters of cyanuric acid or isocyanuric acid such as triallyl cyanurate and triallyl isocyanurate; triallyl phosphonate; triacryloyloxyethyl phosphonate; maleimide compounds such as N-phenylmaleimide and N,N'-m-phenylene bismaleimide; and polyfunctional monomers such as dipropargyl phthalate and dipropargyl maleate, which have two or more triple bonds.

[0112] The crosslinking aid may be a polymer-type substance having an epoxy group capable of bonding to the hydroxyl group and carboxyl group of the polylactic acid resin. This polymer-type crosslinking aid is also suitable for having a chain extension function.

[0113] As the above polymer-type crosslinking aid, for example, an epoxy group-containing (meth)acrylic polymer can be cited.

[0114] As the above epoxy group-containing (meth)acrylic polymer, a styrene-glycidyl (meth)acrylate copolymer can be cited.

[0115] As the styrene-glycidyl (meth)acrylate copolymer, it is preferable that the proportion of glycidyl (meth)acrylate in the copolymer exceeds 20% by mass. The proportion of glycidyl (meth)acrylate in the copolymer is more preferably more than 30% by mass, and particularly preferably more than 50% by mass. The epoxy equivalent in this copolymer is, for example, 150 to 3000 g / eq.

[0116] The above epoxy equivalent may be 200 to 500 g / eq. The weight average molecular weight (Mw) of the above styrene-glycidyl (meth)acrylate copolymer is, for example, 2000 to 25000. The above weight average molecular weight (Mw) may be 3000 to 8000.

[0117] The number average molecular weight (Mn) of the styrene-glycidyl (meth)acrylate copolymer can be set, for example, to 400 to 6000. The number average molecular weight (Mn) may be 1000 to 4000. The dispersity (Q value = Mw / Mn) of the styrene-glycidyl (meth)acrylate copolymer is, for example, 1.5 to 5.

[0118] As the epoxy group-containing (meth)acrylic polymer, commercially available products sold under the trade name "Joncryl" by BASF Corporation, commercially available products sold under the trade name "ARUFON" by Toagosei Company, Limited (English name: Toagosei Company, Limited), and commercially available products sold under the trade name "Marproof" (registered trademark) (English: Marproof) by NOF CORPORATION can be used.

[0119] In addition, although the crosslinking aid also depends on the molecular weight of the polylactic acid resin, etc., it is usually used in a proportion of 2.00 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin to be modified.

[0120] The usage amount of the crosslinking aid is preferably 1.50 parts by mass or less, more preferably 1.00 parts by mass or less, and particularly preferably 0.50 parts by mass or less.

[0121] By making the usage amount of the crosslinking aid as described above 0.10 parts by mass or more, the effect brought about by the modification of the polylactic acid resin can be more reliably exerted.

[0122] [Polylactic Acid Resin Composition]

[0123] The substance obtained by modifying the above-mentioned polylactic acid resin with the above-mentioned organic peroxide becomes a polylactic acid resin composition. The manufacturing method of this polylactic acid resin composition will be described later.

[0124] It should be noted that since it is optional to use a crosslinking aid together with the organic peroxide, the organic peroxide used together with the crosslinking aid and the organic peroxide without the crosslinking aid are collectively referred to as the organic peroxide.

[0125] In addition, the substance obtained by modifying the polylactic acid resin with the organic peroxide is sometimes referred to as the modified polylactic acid resin. In the polylactic acid resin composition of the present invention, a trace amount of the organic peroxide used in the modification may remain. In addition, a mixture can also be made by mixing other substances. These are collectively referred to as the polylactic acid resin composition.

[0126] [Manufacturing Method of Polylactic Acid Resin Composition]

[0127] Based on Figure 1 A preferred example of the manufacturing method of the polylactic acid resin composition will be described.

[0128] As Figure 1 shown, the polylactic acid resin 11 and an appropriate amount of the organic peroxide 12 are put into a mixer 13 such as a ribbon mixer. The mixer 13 is used to fully stir and mix to obtain a mixture 14.

[0129] The obtained mixture 14 is put into an extruder 15. The mixture is melt-kneaded using the extruder 15 to obtain a kneaded product 16 in the form of a wire (rope).

[0130] The obtained kneaded product 16 is sufficiently cooled and cut into a specified length using a cutting machine 17 called a granulator.

[0131] Thus, a polylactic acid resin composition 18 in the form of pellets is obtained. The size of the pellets is, for example, a cylinder with a diameter of 3 mm and a height of 3 mm. These pellets become the specimens in the examples described later. In addition, the pellets are supplied to the injection blow molding apparatus described below.

[0132] [Injection Blow Molding Apparatus]

[0133] The apparatus for obtaining an injection blow molded article using the polylactic acid resin composition (pellets) 18 as a starting material is an injection blow molding apparatus. Based on Figure 2 and Figure 3 a specific example of this apparatus will be described.

[0134] As Figure 2 shown, the injection blow molding apparatus 20 includes an injection device 21, a preform mold 31, and a blow mold 33 as main components.

[0135] The injection device 21 has a heating cylinder 23 with an internal screw 22, includes a heater 24 and a hopper 25, and includes a screw rotation mechanism 26 and a heating cylinder moving mechanism 27.

[0136] The heating cylinder 23 is maintained at, for example, 220°C by the heater 24.

[0137] The preform mold 31 and the blow mold 33 are arranged in a combination mold 35. A rotary head 36 is arranged along the combination mold 35, and a rod-shaped core 37 is mounted on the rotary head 36.

[0138] The rotary head 36 rotates 180° around an axis 39 through a rotation mechanism 38 and moves to a standby position through a moving cylinder 41.

[0139] Through the core 37, a preform cavity 32 is formed in the preform mold 31, and a blow cavity 34 is formed in the blow mold 33.

[0140] The heating cylinder 23 is advanced using the heating cylinder moving mechanism 27 so that the nozzle contacts the preform mold 31. When the screw 22 is rotated by the screw rotation mechanism 26, the polylactic acid resin composition 18 at about 220°C is injected. This process is called the injection process.

[0141] A blow molding process for blow molding is performed using the blow mold 33.

[0142] AsFigure 3 As shown, a fluid passage 43 is provided along the central axis of the core 37, and a plurality of radial passages 44 are provided along a radial axis orthogonal to the central axis. The radial passages 44 extend from the fluid passage 43 and open to the outside of the core 37. A high-pressure fluid source 45 is connected to the fluid passage 43, and the supply and stop of high-pressure fluid (such as compressed air at room temperature) are controlled by a flow path opening and closing valve 46 provided in the mold.

[0143] In the injection process, the radial passages 44 are in a closed state.

[0144] In the above blow molding process, the radial passages 44 are opened by the operation of the flow path opening and closing valve 46, and the high-pressure fluid from the high-pressure fluid source 45 is blown out to the outside of the core 37. As a result, blow molding is performed.

[0145] After the above blow molding process is completed, the radial passages 44 are closed by the operation of the flow path opening and closing valve 46.

[0146] In Figure 2 In the injection blow molding apparatus 20, the rotary head 36 is rotated 180° around the axis 39, but the rotary head 36 may also move linearly without rotation. That is, the axis of the preform mold 31 and the axis of the blow mold 33 are arranged parallel to each other, and the head having the core 37 is moved along an axis orthogonal to these axes. By alternately arranging a plurality of preform molds 31 and a plurality of blow molds 33 along the orthogonal axis, an injection blow molding apparatus with high productivity can be provided.

[0147] Therefore, the injection blow molding apparatus 20 is not limited to the Figure 2 structure described in

[0148] Next, the operation of the injection blow molding apparatus 20 including the above configuration will be described.

[0149] In Figure 2 In the injection device 21, a polylactic acid resin composition at about 220°C is injected into the preform cavity 32 to form a preform. Then, the preform mold 31 is opened, and the rotary head 36 is rotated, thereby moving the preform 47 to the blow mold 33. When measured using a surface thermometer during this movement, the temperature of the preform 47 is about 180°C.

[0150] The temperature of the blow mold 33 is controlled to 25°C to 50°C. The preform 47 is received in the blow mold 33.

[0151] By spraying high-pressure fluid from the Figure 3 radial passages shown, the preform 47 expands in a manner imitating the external shape of the blow mold cavity 34.

[0152] The injection blow-molded article 48 is obtained by opening the blow molding die 33 and removing it from the core 37.

[0153] The injection blow-molded article 48 is obtained by injection blow molding the polylactic acid resin composition of the present invention ( Figure 1 , reference numeral 18). Since the polylactic acid resin composition ( Figure 1 , reference numeral 18) is used, an injection blow-molded article 48 without cracks, cuts, and having good appearance can be obtained.

[0154] In addition, the manufacturing method of the injection blow-molded article is obtained by injection blow molding the polylactic acid resin composition of the present invention ( Figure 1 , reference numeral 18). Since the injection blow-molded article is produced with a high yield, the productivity of the injection blow-molded article can be improved by the manufacturing method of the injection blow-molded article of the present invention.

[0155] More specifically, the manufacturing method of the injection blow-molded article of the present invention includes: a preparation step of preparing an injection blow molding apparatus ( Figure 2 , reference numeral 20), which injection blow molding apparatus has an injection device ( Figure 2 , reference numeral 21) for injecting a molten polylactic acid resin composition and a preform mold ( Figure 2 , reference numeral 47) for molding a preform ( Figure 2 , reference numeral 31) and a blow molding die ( Figure 2 , reference numeral 33);

[0156] A preform molding step of injecting the polylactic acid resin composition into the preform mold ( Figure 2 , reference numeral 31) through the injection device ( Figure 2 , reference numeral 31) to obtain the preform ( Figure 2 , reference numeral 47);

[0157] A transfer step of transferring the obtained preform from the preform mold ( Figure 2 , reference numeral 31) to the blow molding die ( Figure 2 , reference numeral 33); and

[0158] A blow molding step of blow molding the transferred preform with the blow molding die ( Figure 2 , reference numeral 33) to obtain an injection blow-molded article ( Figure 2 , reference numeral 48).

[0159] Examples

[0160] Hereinafter, examples and comparative examples are listed to specifically illustrate the present invention, but the present invention is not limited to the following examples.

[0161] [Preparation of Specimens]

[0162] The specimens were prepared roughly based on Figure 1 However, the detailed preparation procedures for each example and each comparative example are described below.

[0163] (Example 1 (Specimen))

[0164] 100 parts by mass of polylactic acid resin (“FY804” manufactured by Anhui BBCA Biochemical Co., Ltd. (English name: ANHUI BBCABIOCHEMICAL CO., LTD.)) and 0.50 part by mass of organic peroxide: tert-butyl peroxyisopropyl monocarbonate (“Trigonox BPIC-75” manufactured by Kayaku Nouryon Corporation (English name: KAYAKU NOURYON CORPORATION)) were stirred and mixed using a ribbon blender to obtain a mixture.

[0165] The obtained mixture was fed into a twin-screw extruder with a barrel diameter of 57 mm (L / D = 31.5, where D is the outer diameter of the screw and L is the effective length of the screw). The set temperature of the feeding section was set at 170 °C, and the temperature thereafter was set at 200 °C. Under the condition of a rotational speed of 100 rpm, the above mixture was melt-kneaded in the twin-screw extruder, and the kneaded product was extruded in the form of a strand from a die with a diameter of 3 mm and 18 holes installed at the front end of the extruder at a discharge rate of 30 kg / h.

[0166] Next, the extruded strand-shaped kneaded product was passed through a cooling water tank with a length of 2 m containing water at 30 °C for cooling. The cooled strand was cut using a granulator to obtain pellets of the modified polylactic acid resin composition.

[0167] (Example 2 (Specimen))

[0168] The amount of the organic peroxide was set at 0.45 part by mass. Except for this, pellets of the polylactic acid resin composition were prepared by the same method as in Example 1.

[0169] (Example 3 (Specimen))

[0170] Instead of tert-butyl peroxyisopropyl monocarbonate, 0.40 part by mass of α,α'-di-tert-butylperoxydiisopropylbenzene (“PERBUTYL P” manufactured by NOF Corporation) was added as the organic peroxide. Except for this, pellets of the polylactic acid resin composition were prepared by the same method as in Example 1.

[0171] (Example 4 (Specimen))

[0172] As the polylactic acid resin, “FY212” manufactured by Anhui Fengyuan Company was used, and the amount of the organic peroxide was set to 1.30 parts by mass. Except for this, pellets of the polylactic acid resin composition were produced by the same method as in Example 1.

[0173] (Example 5 (Specimen))

[0174] As the polylactic acid resin, “FY804” manufactured by Anhui Fengyuan Company was used. As the organic peroxide, 0.30 part by mass of tert-butylperoxy 3,5,5-trimethylhexanoate (“Trigonox 42” manufactured by Chemische Fabrik Nouryon B.V.) was used, and 0.50 part by mass of an epoxy group-containing acrylic acid-modified styrene resin (“Joncryl ADR 4468” manufactured by BASF SE) as a crosslinking aid was used. Except for this, pellets of the polylactic acid resin composition were produced by the same method as in Example 1.

[0175] (Comparative Example 1 (Specimen))

[0176] As the polylactic acid resin, “FY801” manufactured by Anhui Fengyuan Company was used. Except for this, pellets of the polylactic acid resin composition were produced by the same method as in Example 1.

[0177] (Comparative Example 2 (Specimen))

[0178] As the polylactic acid resin, “FY804” manufactured by Anhui Fengyuan Company was used, but the modification operation was not performed and it was used directly.

[0179] (Comparative Example 3 (Specimen))

[0180] As the polylactic acid resin, “Biopolymer Ingeo 4032D” manufactured by Nature Works LLC was used. Except for this, pellets of the polylactic acid resin composition were produced by the same method as in Example 1.

[0181] (List of Specimens)

[0182] When the specimens described above are presented in an easily observable manner as a list, it is as follows. That is, Table 1 shows the grades of the polylactic acid resin, Table 2 shows the grades of the organic peroxide and the crosslinking aid, and Table 3 shows the composition of the specimen, that is, the pellet-shaped polylactic acid resin composition.

[0183] Table 1

[0184]

[0185] 4032D: Biopolymer Ingeo 4032D

[0186] Table 2

[0187]

[0188] BPIC - 75: tert - butyl peroxy isopropyl monocarbonate

[0189] 2 PERBUTYL P: α,α′ - di - tert - butyl peroxy diisopropylbenzene

[0190] 3 Trigonox 42: tert - butyl peroxy 3,5,5 - trimethylhexanoate

[0191] 4 Joncryl ADR 4468: epoxy - group - containing acrylic - modified styrene - based resin

[0192]

[0193] In order to evaluate each specimen, various physical property values were measured. The measurement methods and various physical property values obtained are described below.

[0194] It should be noted that only the proportion of the following D - form is measured using polylactic acid resin because there is no difference in the polylactic acid resin and the modified polylactic acid resin composition.

[0195] [Proportion of D - form]

[0196] In polylactic acid resin, when the proportion of the D - form is too small, the crystallization rate becomes fast, and crystallization occurs during injection blow molding, resulting in a decrease in moldability. In addition, when the proportion of the D - form in polylactic acid resin is too large, the resin yellows significantly, and the appearance deteriorates. Therefore, it is required to control the proportion of the D - form within an appropriate range.

[0197] (Preferred proportion of D - form)

[0198] The proportion of the D - form in polylactic acid resin is preferably 3.0 mol% or more and 20.0 mol% or less, more preferably 3.3 mol% or more and 18 mol% or less, and particularly preferably 3.5 mol% or more and 15 mol% or less.

[0199] The same applies to the polylactic acid resin composition.

[0200] (Measurement method for proportion of D - form)

[0201] The measurement method for the proportion of the D - form in the total of the D - form and the L - form is described below.

[0202] The lactic acid content of the D-form or L-form in the polylactic acid resin can be measured by the following method. Freeze-crush the polylactic acid resin. Supply 200 mg of the powder of the crushed polylactic acid resin into an Erlenmeyer flask. Then, add 30 mL of 1N sodium hydroxide aqueous solution into the Erlenmeyer flask. Next, heat to 65 °C while shaking the Erlenmeyer flask to completely dissolve the polylactic acid resin.

[0203] Next, supply 1N hydrochloric acid into the above Erlenmeyer flask for neutralization to prepare a decomposition solution with a pH of 4 to 7. The prepared decomposition solution is made into a specified volume using a volumetric flask. Then, filter the decomposition solution with a 0.45 μm membrane filter. Analyze the filtered decomposition solution using liquid chromatography. Based on the chart obtained through the analysis, calculate the area ratio as the existence ratio from the peak areas derived from the D-form and L-form, and calculate the amounts of the D-form and L-form.

[0204] Repeat the above measurement method 5 times. Add and average the obtained amounts of the D-form and L-form respectively as the amounts of the D-form and L-form in the polylactic acid resin.

[0205] Above, the polylactic acid resin has been described, but the same measurement method is also used to confirm the ratio of the D-form in the polylactic acid resin composition.

[0206] (Measurement conditions for liquid chromatography)

[0207] Liquid chromatography device (High Performance Liquid Chromatograph): Product name PU-2085Plus type system manufactured by JASCO Corporation

[0208] Column: Product name SUMICHIRAL OA5000 (diameter 4.6 mm × length 250 mm) manufactured by Sumika Chemical Analysis Service, Ltd.

[0209] Column temperature: 25 °C

[0210] Mobile phase: Mixture of 2 mM CuSO 4 aqueous solution and 2-propanol (CuSO 4 aqueous solution: 2-propanol (volume ratio) = 95:5)

[0211] Mobile phase flow rate: 1.0 mL / minute

[0212] Detector: UV 254 nm

[0213] Injection volume: 20 μL

[0214] (Ratio of the D-form obtained during the measurement)

[0215] The proportion of the D-form in Example 1 was 3.5 mol%, the proportion of the D-form in Example 2 was 3.5 mol%, the proportion of the D-form in Example 3 was 3.5 mol%, the proportion of the D-form in Example 4 was 12.0 mol%, the proportion of the D-form in Example 5 was 3.5 mol%, the proportion of the D-form in Comparative Example 1 was 1.0 mol%, the proportion of the D-form in Comparative Example 2 was 3.5 mol%, and the proportion of the D-form in Comparative Example 3 was 1.4 mol%.

[0216] [Melt tension]

[0217] When the melt tension is too small, it results in low strength and sometimes the molded body breaks during injection blow molding. Additionally, when the melt tension is too large, it is difficult to stretch and sometimes the molded body is cut during injection blow molding. Therefore, an appropriate range of melt tension is required.

[0218] (Preferred melt tension)

[0219] The polylactic acid resin composition of the present embodiment exhibits specific characteristic values in the measurement of melt tension at 190 °C.

[0220] Specifically, the polylactic acid resin composition exhibits a melt tension of 20.0 cN or more and 85.0 cN or less in the measurement of melt tension at 190 °C.

[0221] The melt tension of the polylactic acid resin composition is preferably 80.0 cN or less, more preferably 75.0 cN or less, further preferably 65 cN or less, further preferably 63.0 cN or less, and still more preferably 60.0 cN or less.

[0222] The melt tension of the polylactic acid resin composition is preferably 22.0 cN or more, and more preferably 25.0 cN or more.

[0223] The polylactic acid resin composition of the present embodiment can suppress the breakage of the molded body during blow molding by having a melt tension of 20.0 cN or more.

[0224] In addition, the polylactic acid resin composition of the present embodiment exhibits good elongation during blow molding and can suppress cutting by having a melt tension of 85.0 cN or less.

[0225] (Method for measuring melt tension)

[0226] The melt tension was measured using a "Capilograph1D" (special specification for heating furnace) capillary rheometer manufactured by TOYO SEIKI SEISAKU-SHO, LTD. and a "Rheotens71.97" manufactured by GoettFert. The measurement conditions are as described below.

[0227] (Measurement conditions)

[0228] The sample was pre-vacuum dried at 70°C for 5 hours in advance. The Rheotens71.97 was set so that the distance from the die outlet of the Capilograph1D to the measurement section was 80 mm. First, after filling the sample into the barrel heated to 190°C, it was preheated for 5 minutes. It should be noted that the measurement time, including the preheating time after filling into the barrel, did not exceed 10 minutes. Then, a piston was inserted from the upper part of the barrel, and the molten resin was extruded in a rope shape. At this time, the piston descent speed (20 mm / min) was kept constant and the extruded rope was passed through the measuring wheel of the Rheotens. Then, the traction speed was gradually increased, and the melt tension of the sample was measured.

[0229] For the measurement results, the average value of the maximum and minimum values of the tension before the point where the rope broke was taken as the melt tension of the sample.

[0230] It should be noted that when there is only one maximum point in the tension chart, the maximum value is taken as the melt tension.

[0231] In addition, when the rope became thinner and wound into an idling state, that moment was taken as the break point, and the average value of the maximum and minimum values of the tension before that was taken as the melt tension of the sample.

[0232] (Measurement conditions of Capilograph1D)

[0233] Die: diameter 2.095 mm, length 8 mm, inlet angle 90 degrees (conical)

[0234] Barrel diameter: 9.55 mm

[0235] Piston speed: 20 mm / min

[0236] Measurement temperature: 190°C

[0237] (Measurement conditions of Rheotens)

[0238] Measuring wheel interval: upper 0.6 - 0.8 mm, lower 1.0 mm

[0239] Acceleration: 10 mm / s 2

[0240] Drawing speed: initial speed 6.92 mm / s

[0241] (Melt tension obtained during measurement)

[0242] The melt tension of Example 1 was 51.8 cN, that of Example 2 was 47.5 cN, that of Example 3 was 52.4 cN, that of Example 4 was 28.7 cN, that of Example 5 was 72.3 cN, that of Comparative Example 1 was 48.8 cN, that of Comparative Example 2 was 1.7 cN, and that of Comparative Example 3 was 68.5 cN.

[0243] [Crystallization temperature]

[0244] In the injection blow molding method, a preform is formed by a preform mold, and the preform is blow molded by an injection blow mold. Inside the blow mold, the preform is rapidly cooled. The high-temperature polylactic acid resin composition sometimes crystallizes during the temperature drop.

[0245] When crystallization occurs at the initial stage of injection blow molding, it hinders subsequent blow molding. In contrast, even if crystallization occurs at the end stage of blow molding (when blow molding ends), it does not cause hindrance.

[0246] Therefore, the crystallization temperature is measured.

[0247] (Preferred crystallization temperature)

[0248] The crystallization temperature of the polylactic acid resin composition is preferably 120 °C or lower, more preferably 118 °C or lower, and particularly preferably 115 °C or lower during the temperature drop of 5 °C / minute using a differential scanning calorimeter.

[0249] The polylactic acid resin composition of the present embodiment can suppress crystallization during injection blow molding and can suppress blow molding defects caused by crystallization by making the crystallization temperature 120 °C or lower.

[0250] (Method for measuring crystallization temperature)

[0251] The crystallization temperature is measured by the method described in JIS K7121:1987 and JIS K7121:2012. Among them, the sampling method / temperature conditions are as follows.

[0252] 5.5 ± 0.5 mg of the sample is filled at the bottom of an aluminum measurement container without gaps. Aluminum lids are respectively placed on the above containers.

[0253] Next, differential scanning calorimetry analysis was performed using a "DSC7000X, AS-3" differential scanning calorimeter manufactured by Hitachi High-Tech Science Corporation. Under a nitrogen flow rate of 20 mL / min, the sample was heated / cooled in the following steps to obtain a differential scanning calorimetry curve (hereinafter abbreviated as DSC curve).

[0254] (Step 1) Heat from 30 °C to 210 °C and hold for 10 minutes.

[0255] (Step 2) Cool (descend in temperature) from 210 °C to 0 °C.

[0256] It should be noted that all heating / cooling was carried out at a rate of 5 °C / min. Alumina was used as the reference substance. Using the analysis software attached to the device, the top temperature of the crystallization peak observed during the cooling process was read as the crystallization temperature.

[0257] For ease of understanding, the heating curve for crystallization temperature and the heating curve for crystallization time are shown in Figure 4 . It should be noted that the heating curve for crystallization time is used later.

[0258] Figure 4 In, in the heating curve for crystallization temperature, during the cooling process shown in (Step 2), a crystallization peak is expected to occur.

[0259] (Crystallization temperature obtained during measurement)

[0260] Figure 5 DSC curve graph showing the crystallization temperature of Example 1.

[0261] As shown in Figure 5 , the crystallization temperature of Example 1 was 112 °C.

[0262] Although the DSC curve graph is omitted, the crystallization temperature of Example 2 was 113 °C, the crystallization temperature of Example 3 was 110 °C, the crystallization temperature of Example 5 was 114 °C, the crystallization temperature of Comparative Example 1 was 136 °C, and the crystallization temperature of Comparative Example 3 was 128 °C.

[0263] Although the DSC curve graph is omitted, there is no crystallization peak as shown in Figure 5 for Example 4 and Comparative Example 2.

[0264] [Crystallization time]

[0265] In the case of crystallization during the cooling process in injection blow molding, the later the crystallization starts, the less it will cause interference. Therefore, the crystallization time was measured.

[0266] (Method for Measuring Crystallization Time)

[0267] The crystallization time is measured by the following method. The sampling method / temperature conditions are as follows. 5.5 ± 0.5 mg of the sample is filled at the bottom of an aluminum measuring container without gaps. Then, an aluminum lid is placed on the above container.

[0268] Next, differential scanning calorimetry is performed using the "DSC7000X, AS-3" differential scanning calorimeter manufactured by Hitachi High-Technologies Corporation. Based on a nitrogen flow rate of 20 mL / minute, the sample is heated / cooled in the following steps to obtain a DSC curve.

[0269] (Step 1) After heating from 20°C to 200°C at (100°C / minute), it is held at 200°C for 5 minutes.

[0270] (Step 2) After cooling from 200°C to 130°C at (100°C / minute), it is held at 130°C for crystallization. The crystallization time is the half-value from the start time of the crystallization peak to the peak time of the crystallization peak.

[0271] Figure 4 The heating curve showing the crystallization time is shown.

[0272] In Figure 4 the heating curve of the crystallization time, during holding at 130°C, a crystallization peak may occur. Since it is a possibility, there may sometimes be no crystallization peak.

[0273] (Crystallization Time Obtained during Measurement)

[0274] Figure 6 DSC curve graph showing the crystallization time of Comparative Example 1.

[0275] As Figure 6 shown, in Comparative Example 1, a crystallization peak exists during holding at 130°C. The crystallization time in Comparative Example 1 is 8.45 minutes.

[0276] Although the crystallization peak is omitted, in Comparative Example 3, a crystallization peak exists during holding at 130°C, and the crystallization time is 8.95 minutes.

[0277] Although the crystallization peak is omitted, in Example 5, a crystallization peak exists during holding at 130°C, and the crystallization time is 23.10 minutes.

[0278] In contrast, in Example 1, Example 2, Example 3, Example 4, and Comparative Example 2, no crystallization peak exists during holding at 130°C.

[0279] [Melt Mass Flow Rate (MFR)]

[0280] In resin molding, the fluidity of the resin material is important. When the fluidity is too poor, the filling of the mold cavity is insufficient, resulting in poor molding. When the fluidity is too good, leakage occurs from the gaps of the mold. The same applies to the polylactic acid resin composition.

[0281] The polylactic acid resin composition preferably exhibits moderate fluidity when thermally melted.

[0282] (Preferred melt mass flow rate)

[0283] The melt mass flow rate of the polylactic acid resin composition at a temperature of 190 °C and a nominal load of 21.18 N is preferably 0.1 g / 10 min or more, more preferably 0.2 g / 10 min or more, and particularly preferably 0.3 g / 10 min or more.

[0284] In addition, the melt mass flow rate of the polylactic acid resin composition at a temperature of 190 °C and a nominal load of 21.18 N is preferably 20.0 g / 10 min or less, more preferably 18.0 g / 10 min or less, further preferably 15.0 g / 10 min or less, further preferably 10.0 g / 10 min or less, and particularly preferably 8.0 g / 10 min or less.

[0285] (Method for measuring melt mass flow rate)

[0286] The melt mass flow rate is measured in accordance with JIS K 7210:1999. The melt mass flow rate is measured by the method of "b) Measuring the time for the piston to move a specified distance" described in Method B of this standard. The melt mass flow rate is measured using the "Melt Flow Rate Tester (Automatic) 120-SAS" manufactured by Yasuda Seiki Seisakusho, Ltd. (English name: YASUDA SEIKI SEISAKUSHO, LTD.). The test sample is the sample that has been vacuum dried at 70 °C for 5 hours, sealed just before measurement, and stored in a desiccator.

[0287] (Measurement conditions for melt mass flow rate)

[0288] Test sample: 3 - 8 g

[0289] Preheating 1: 200 seconds

[0290] Preheating 2: 30 seconds

[0291] Test temperature: 190 °C

[0292] Test load (nominal load): 21.18 N

[0293] Piston movement distance (interval): 25 mm

[0294] The test of the specimen was conducted 3 times, and the average value was taken as the melt mass flow rate (g / 10 min).

[0295] (Melt mass flow rate (MFR) obtained in the measurement)

[0296] The MFR of Example 1 was 0.3 g / 10 min, the MFR of Example 2 was 0.4 g / 10 min, the MFR of Example 3 was 1.2 g / 10 min, the MFR of Example 4 was 8.2 g / 10 min, the MFR of Example 5 was 0.6 g / 10 min, the MFR of Comparative Example 1 was 2.5 g / 10 min, the MFR of Comparative Example 2 was 4.3 g / 10 min, and the MFR of Comparative Example 3 was 2.3 g / 10 min.

[0297] [Shear viscosity]

[0298] In the case of having crystallinity, by maintaining a higher temperature during molding and delaying the arrival at the crystallization temperature, good moldability can be achieved. If the shear viscosity is high, a certain degree of viscosity can be maintained even at a high temperature, and the temperature during molding can be increased.

[0299] Therefore, the shear viscosity of the polylactic acid resin composition was measured.

[0300] (Measurement of shear viscosity)

[0301] The measurement of shear viscosity was carried out using a capillary rheometer "Capilograph1D" (special specification for heating furnace) manufactured by Toyo Seiki Seisaku-sho, Ltd. under the following conditions.

[0302] (Measurement conditions for shear viscosity)

[0303] The specimen was vacuum-dried at 70 °C for 5 hours in advance.

[0304] (Measurement conditions for Capilograph1D)

[0305] Die: diameter 1.0 mm, length 10 mm, inlet angle 90 degrees (conical)

[0306] Barrel diameter: 9.55 mm

[0307] Piston speed: 8.22 mm / min (shear rate 100 1 / s))

[0308] Measurement temperature: 190 °C

[0309] Preheating time: 5 minutes

[0310] (Shear viscosity obtained in the measurement)

[0311] The shear viscosity of Example 1 was 2456 Pa·s, that of Example 2 was 2467 Pa·s, that of Example 3 was 1756 Pa·s, that of Example 4 was 699 Pa·s, that of Example 5 was 2430 Pa·s, that of Comparative Example 1 was 1182 Pa·s, that of Comparative Example 2 was 1070 Pa·s, and that of Comparative Example 3 was 733 Pa·s.

[0312] [Gel fraction]

[0313] If the proportion of the gel (gel fraction) is large, the appearance deteriorates. Therefore, the gel fraction was measured.

[0314] (Preferred gel fraction)

[0315] The gel fraction contained in the polylactic acid resin composition of the present embodiment is preferably 15.0% by mass or less, more preferably 13.0% by mass or less, and particularly preferably 10.0% by mass or less.

[0316] (Method for measuring gel fraction)

[0317] The measurement of the gel fraction (mass%) was carried out by the following method. Prepare about 0.5 g of the sample and accurately weigh the initial mass (m0 (g)) of the sample. In addition, prepare a 200-mesh metal mesh (wire diameter 0.05 mm) for filtering the solution in which the sample is dissolved. Also accurately weigh the initial mass (M0 (g)) of the metal mesh. Put the weighed test sample into a beaker (100 mL). Add 50 mL of chloroform as a solvent and a stir bar to the beaker, and cover it with aluminum foil. Stir with a stirrer for 2 hours and dissolve it at room temperature. After 2 hours, remove the aluminum foil and filter the dissolved matter in the beaker with the above metal mesh. After filtration, naturally dry the metal mesh in a fume hood for 12 hours or more. After natural drying, further dry the metal mesh in a thermostatic dryer at 120 °C for 2 hours. Cool the dried metal mesh with a desiccator. After cooling, weigh the metal mesh with resin insoluble matter attached, and calculate the gel fraction from the following formula.

[0318] (Calculation method of gel fraction)

[0319] Gel fraction (mass%) = (m1 / m0) × 100

[0320] m0: Initial mass of the sample

[0321] m1: Mass of resin insoluble matter (M1 - M0)

[0322] M0: Initial mass of the metal mesh

[0323] M1: Total mass of resin insoluble matter and metal mesh

[0324] (Gel fraction obtained during measurement)

[0325] The gel fraction of Example 1 was 1.1% by mass, that of Example 2 was 0.9% by mass, that of Example 3 was 1.8% by mass, that of Example 4 was 11.7% by mass, that of Example 5 was 0.7% by mass, that of Comparative Example 1 was 4.0% by mass, that of Comparative Example 2 was 0.4% by mass, and that of Comparative Example 3 was 3.9% by mass.

[0326] [Prototype production and evaluation of injection blow molded articles]

[0327] (Prototype production of injection blow molded articles)

[0328] The polylactic acid resin composition (pellets) having the composition shown in Table 3 was supplied to Figure 2 the injection blow molding apparatus 20 shown, and a preform ( Figure 2 , reference numeral 47) was produced using the injection blow molding apparatus 20, and the preform was blow molded to produce a prototype injection blow molded article ( Figure 2 , reference numeral 48).

[0329] (Evaluation of continuous blow molding property)

[0330] The injection blow molding apparatus ( Figure 2 , reference numeral 20) was continuously operated to obtain a plurality of test articles. At this time, it was evaluated whether smooth blow molding was performed without delay.

[0331] The best evaluation was rated as ◎ (very good), good was rated as 〇 (good), and poor was rated as × (bad).

[0332] For Example 1 it was 〇, for Example 2 it was ◎, for Example 3 it was ◎, for Example 4 it was 〇, for Example 5 it was ◎, for Comparative Example 1 it was ×, for Comparative Example 2 it was ×, and for Comparative Example 3 it was ×.

[0333] (Evaluation of single - time blow molding property)

[0334] The injection blow molding apparatus ( Figure 2 , reference numeral 20) was operated once to obtain one test article. At this time, it was evaluated whether smooth blow molding was performed without delay.

[0335] For Example 1 it was 〇, for Example 2 it was ◎, for Example 3 it was ◎, for Example 4 it was 〇, for Example 5 it was ◎, for Comparative Example 1 it was ×, for Comparative Example 2 it was ×, and for Comparative Example 3 it was ×.

[0336] (Evaluation of appearance)

[0337] The appearance of the test articles obtained during continuous operation and single - time operation was observed.

[0338] Example 1 is ◎, Example 2 is ◎, Example 3 is ◎, Example 4 is 〇, Example 5 is ◎, Comparative Example 1 is ×, Comparative Example 2 is ×, and Comparative Example 3 is ×.

[0339] The above evaluations are summarized in Table 4.

[0340]

[0341] (Evaluation of injection blow molding formability)

[0342] In Table 4, if the continuous blow molding formability, single blow molding formability, and appearance are all ◎, the comprehensive evaluation is ◎.

[0343] In Table 4, if the continuous blow molding formability, single blow molding formability, and appearance are all a mixture of ◎ and 〇 or all 〇, the comprehensive evaluation is 〇.

[0344] In Table 4, if the continuous blow molding formability, single blow molding formability, and appearance are all ×, the comprehensive evaluation is ×.

[0345] Hereinafter, the above comprehensive evaluation is referred to as "injection blow molding formability".

[0346] On this basis, the composition, various physical property values, and evaluations of the above-mentioned polylactic acid resin composition are summarized in Table 5.

[0347]

[0348] To examine Table 5, the following (a) to (c) are presented. Figure 7 as follows.

[0349] Figure 7 (a) is a diagram illustrating the shape at the initial stage of blow molding. Figure 7 (b) is a diagram illustrating the shape at the middle stage of blow molding. Figure 7 (c) is a diagram illustrating the shape at the final stage of blow molding.

[0350] In Figure 7 (a), compressed air is ejected from the core 37 to the inner peripheral surface of the parison 47 to start blow molding. At this time, the temperature t1 of the parison 47 is presumed to be about 150 °C.

[0351] In Figure 7 (b), the parison 47 gradually expands in the blow molding cavity 34. At this time, the parison 47 is cooled by normal temperature compressed air and the blow molding die 33 at 25 °C to 50 °C. The temperature t2 of the parison 47 at this time is presumed to be about 130 °C.

[0352] In Figure 7(c), the outer peripheral surface of the preform 47 comes into contact with the blow mold 33, and the swelling is completed. The temperature t3 of the preform 47 at this time is presumed to be about 120°C. Thereafter, the preform 47 is sufficiently cooled to become an injection blow molded body 48.

[0353] In Table 5 above, when focusing on the "crystallization temperature during temperature drop at 5°C / min" in the middle section, Comparative Example 1 was 136°C and Comparative Example 3 was 128°C. These temperatures are close to temperature t2 (about 130°C). It is considered that crystallization occurred in Comparative Example 1 and Comparative Example 2 at the Figure 7 (b) stage, which hindered the subsequent blow molding, and the result was evaluated as ×.

[0354] In contrast, the crystallization temperatures during temperature drop at 5°C / min for Examples 1 to 3 and Example 5 were 120°C or lower. This temperature is close to temperature t3 (about 120°C) or lower. In Examples 1 to 3 and Example 5, Figure 7 crystallization occurred in (c). In Examples 1 to 3 and Example 5, crystallization did not occur during the expansion, so the blow moldability was good and the evaluation was ○ or ◎.

[0355] Since there was no crystallization peak during temperature drop at 5°C / min in Example 4, the blow moldability was good and the evaluation was ○.

[0356] It should be noted that Comparative Example 2 had no crystallization peak during temperature drop at 5°C / min, but the melt tension was 1.7 cN. When the melt tension is lower than 20.0 cN, due to insufficient strength, it ruptures during blow molding. Therefore, the evaluation was ×.

[0357] From the above description, it can be seen that for a polylactic acid resin composition with a melt tension of 20.0 cN or more and 85.0 cN or less at 190°C and a crystallization temperature of 120°C or lower or no crystallization peak during the temperature drop process of 5°C / min using a differential scanning calorimeter, the injection blow moldability is good.

[0358] Industrial Applicability

[0359] The polylactic acid resin composition of the present invention is suitable for injection blow molding.

[0360] Explanation of Reference Numerals

[0361] 11... polylactic acid resin, 12... organic peroxide, 18... polylactic acid resin composition, 20... injection blow molding device, 21... injection device, 31... preform mold, 33... blow mold, 47... preform, 48... injection blow molded body.

Claims

1. A polylactic acid resin composition for injection blow molding, which is a polylactic acid resin composition for injection blow molding obtained by modifying a polylactic acid resin with an organic peroxide, wherein, the melt tension at 190 °C is 20.0 cN or more and 85.0 cN or less, the crystallization temperature during the cooling process at 5 °C / minute using a differential scanning calorimeter is 120 °C or less or there is no crystallization peak.

2. The polylactic acid resin composition for injection blow molding according to claim 1, wherein, the melt mass flow rate of the polylactic acid resin composition at a temperature of 190 °C and a nominal load of 21.18 N is 0.1 g / 10 min or more and 20.0 g / 10 min or less.

3. The polylactic acid resin composition for injection blow molding according to claim 1, wherein, the melt mass flow rate of the polylactic acid resin composition at a temperature of 190 °C and a nominal load of 21.18 N is 0.1 g / 10 min or more and 10.0 g / 10 min or less.

4. The polylactic acid resin composition for injection blow molding according to any one of claims 1 to 3, wherein, the proportion of the D-form in the total of the D-form and the L-form in the polylactic acid resin composition is 3.0 mol% or more and 20.0 mol% or less.

5. The polylactic acid resin composition for injection blow molding according to any one of claims 1 to 3, wherein, the proportion of the D-form in the total of the D-form and the L-form in the polylactic acid resin composition is 3.3 mol% or more and 18.0 mol% or less.

6. The polylactic acid resin composition for injection blow molding according to any one of claims 1 to 3, wherein, the proportion of the D-form in the total of the D-form and the L-form in the polylactic acid resin composition is 3.5 mol% or more and 15.0 mol% or less.

7. The polylactic acid resin composition for injection blow molding according to any one of claims 1 to 3, wherein, relative to 100 parts by mass of the polylactic acid resin, the modification is carried out using the organic peroxide in a proportion of 0.10 part by mass or more and 3.00 parts by mass or less.

8. A method for manufacturing a polylactic acid resin composition, which is a method for manufacturing a polylactic acid resin composition according to any one of claims 1 to 3, wherein, relative to 100 parts by mass of a polylactic acid resin in which the proportion of the D-form in the total of the D-form and the L-form is 3.0 mol% or more and 20.0 mol% or less, the organic peroxide is melt-kneaded in a proportion of 0.10 part by mass or more and 3.00 parts by mass or less to produce.

9. An injection blow molded article, which is obtained by injection blow molding the polylactic acid resin composition according to any one of claims 1 to 3.

10. A method for manufacturing an injection blow molded article, wherein, the injection blow molded article is obtained by injection blow molding the polylactic acid resin composition according to any one of claims 1 to 3.

11. A method for manufacturing an injection blow molded article, which is the method for manufacturing an injection blow molded article according to claim 10, comprising: A preparation process, preparing an injection blow molding apparatus, the injection blow molding apparatus having an injection device for injecting the molten polylactic acid resin composition, a preform mold for forming a preform, and a blow mold for blow molding; A preform forming process, injecting the polylactic acid resin composition into the preform mold through the injection device to obtain the preform; A transfer process, transferring the obtained preform from the preform mold to the blow mold; and A blow molding process, obtaining an injection blow molded article by blow molding the transferred preform with the blow mold.

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