JP4260794B2 - Manufacturing method of biodegradable resin molded products - Google Patents

Description

The present invention relates to a biodegradable resin molded article production method.

  Among the biodegradable resins, polylactic acid resins are made from saccharides from corn, straw, etc., and a large amount of L-lactic acid is produced by fermentation. The use of the obtained resin is expected because it has a characteristic that it has little rigidity and has high rigidity and good transparency. However, polylactic acid resin is brittle, hard, and lacks flexibility, all of which are limited to the field of hard molded products. When molded into a sheet or container, the flexibility is insufficient or when it is bent There is a problem such as whitening, and the current situation is that it is not used in the soft or semi-rigid field. In addition, the polylactic acid resin has a slow crystallization rate and is in an amorphous state after molding unless a mechanical process such as stretching is performed. However, since the glass transition temperature (Tg) of polylactic acid is as low as 60 ° C. and poor in heat resistance, there is a problem that it cannot be used in an environment where the temperature is 55 ° C. or higher. In addition, the polylactic acid resin has a slow crystallization rate and is in an amorphous state after molding unless a mechanical process such as stretching is performed. However, since the glass transition temperature (Tg) of polylactic acid is as low as 60 ° C. and poor in heat resistance, there is a problem that it cannot be used in an environment where the temperature is 55 ° C. or higher.

  Various methods have been proposed for adding a plasticizer as a technique for applying polylactic acid resin to soft and semi-rigid fields, or for crystallizing by adding a crystal nucleating agent to improve heat resistance. Reference 1 discloses that an aliphatic polyester composition containing a transparent nucleating agent such as an aliphatic carboxylic acid amide having a melting point of 40 to 300 ° C. is molded and heat-treated at the time of molding or after molding. And a method for producing an aliphatic polyester molded body having both crystallinity. Furthermore, Patent Document 2 discloses a lactic acid polymer composition containing an amide compound having a specific structure, a plasticizer, and a lactic acid polymer, and a method for producing a molded body thereof.

In the case where the resin composition described in Patent Documents 1 and 2 is formed into a sheet in an amorphous state and a crystallized product is obtained when thermoforming such as vacuum forming is performed, the mold temperature is set to 100 because the crystallization speed is low. There was a problem in that the productivity was inferior because the temperature was raised to over ℃ or a long mold holding time was required.
On the other hand, Patent Document 3 proposes a method of obtaining a molded body by stretching and orientation during thermoforming. In this case, at the time of demolding, the molded body can be obtained without cooling the molded body to Tg or less, but the flat portion where the sheet remains as it is or the portion where the stretching orientation is insufficient is inferior in strength and impact resistance, and the whole However, there was a problem inferior in heat resistance without crystallizing.
Japanese Patent No. 3411168 International Publication No. 2003/042302 Pamphlet Japanese Patent No. 3563436

The subject of this invention is providing the manufacturing method with high productivity by the thermoforming method of a biodegradable resin molded product with favorable softness | flexibility, heat resistance, temperature sensitivity, and impact resistance .

The present invention relates to a polylactic acid resin, a plasticizer comprising a compound having 2 or more ester groups in the molecule and having an average addition mole number of ethylene oxide of 2 to 9 , an ester group, a hydroxyl group and an amide in the molecule. A crystal nucleating agent composed of an aliphatic compound having two or more of at least one group selected from a group, and a hydrolysis inhibitor, and a plasticizer content in an amount of 5 to 70 wt. Part, the production method of a biodegradable resin molded product for thermoforming a sheet or film made of a biodegradable resin composition having a content of crystal nucleating agent of 0.1 to 5 parts by weight , comprising the following step (1 ) And step (2), a method for producing a biodegradable resin molded product is obtained which obtains a molded product crystallized to a relative crystallinity of 80% or more.

Step (1): heat the sheet or film made of a biodegradable resin composition, to a temperature below the melting point (Tm) of the glass transition temperature (Tg) of more biodegradable resin composition of the biodegradable resin composition Engineering as step (2): step a sheet or film obtained in (1), at a mold temperature of 60 to 100 [° C., the step of thermoforming

  By the method for producing a biodegradable resin molded article of the present invention, a biodegradable resin molded article having excellent flexibility, heat resistance, temperature sensitivity and impact resistance can be produced with good productivity. When applied to a transparent biodegradable resin such as, a molded product with good transparency can be obtained.

[Polylactic acid resin]
The polylactic acid resin used in the present invention is polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid and the like, and glycolic acid and hydroxycaproic acid are preferable. A preferred molecular structure of polylactic acid is composed of 20 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 20 mol% of each enantiomer. The copolymer of lactic acid and hydroxycarboxylic acid is composed of 85 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 15 mol% of hydroxycarboxylic acid units. These polylactic acid resins can be obtained by dehydrating polycondensation using L-lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material by selecting those having the required structure. Preferably, it can be obtained by ring-opening polymerization by selecting a desired structure from lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone. Lactide includes L-lactide, which is a cyclic dimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lactic acid, meso-lactide obtained by cyclic dimerization of D-lactic acid and L-lactic acid, and D- There is DL-lactide, which is a racemic mixture of lactide and L-lactide. Any lactide can be used in the present invention. However, the main raw material is preferably D-lactide or L-lactide.

  Examples of the commercially available polylactic acid resin include Mitsui Chemicals, Inc., trade name Racia; Cargill Dow Polymers, trade name Nature works, and the like.

  Among these polylactic acid resins, from the viewpoint of crystallization speed and physical properties, L-lactic acid is a high-purity product, particularly a grade of L-lactic acid, particularly LACEA H-400, LACEA H-100, LACEA H-440, manufactured by Mitsui Chemicals. A polylactic acid resin having an L-lactic acid purity of 95% or more, particularly, LACEA H-400, LACEA H-100, manufactured by Mitsui Chemicals, Inc. is more preferable.

[Plasticizer]
Plasticizers used in the present invention, in molecular having two or more ester groups, the average number of moles of added ethylene oxide is 2 to 9, in particular the compounds of 3-9. Examples of such compounds include esters of polyvalent carboxylic acids and polyethylene glycol monoalkyl ethers, alkyl ether esters of polyhydric alcohols, and the like.

  The average molecular weight of the plasticizer used in the present invention is preferably from 250 to 700, more preferably from 300 to 600, still more preferably from 350 to 550, particularly preferably from the viewpoint of bleed resistance and volatile resistance. Is 400-500. The average molecular weight can be obtained by calculating the saponification value by the method described in JISK0070 and calculating from the following formula.

    Average molecular weight = 56108 × (number of ester groups) / saponification value

  Among such plasticizers, from the viewpoint of excellent moldability and impact resistance of the biodegradable resin molded product, an ester of succinic acid and polyethylene glycol monomethyl ether having an average added mole number of ethylene oxide of 2 to 4, Esters of adipic acid and polyethylene glycol monomethyl ether having an average addition mole number of ethylene oxide of 2 to 3, polyethylene glycol monomethyl ether of 1,3,6-hexanetricarboxylic acid and ethylene oxide having an average addition mole number of 2 to 3 Ester of polyvalent carboxylic acid such as ester of polyethylene glycol monomethyl ether; ester of acetic acid and glycerin in ethylene oxide average 3 to 9 mol adduct, polyethylene glycol having an average addition mole number of acetic acid and ethylene oxide in 4 to 9 Multivalent ester such as Alkyl ether esters of alcohol are more preferred. From the viewpoint of excellent moldability, impact resistance and bleed resistance of plasticizers of biodegradable resin molded products, esters of polyethylene glycol monomethyl ether having an average addition mole number of succinic acid and ethylene oxide of 2 to 3, adipic acid Esters of 1,3,6-hexanetricarboxylic acid and diethylene glycol monomethyl ether, esters of acetic acid and glycerol with an average of 3 to 6 moles of ethylene oxide adducts, average addition moles of acetic acid and ethylene oxide More preferred are esters with polyethylene glycol having a number of 4-6. From the viewpoints of moldability, impact resistance, plasticizer bleed resistance, volatilization resistance and pungent odor resistance of biodegradable resin molded products, esters of succinic acid and triethylene glycol monomethyl ether, ethylene oxide of acetic acid and glycerin Particularly preferred are esters with an average of 3-6 mole adducts. These plasticizers may be used alone or in combination of two or more.

  In addition, it is preferable that the ester of this invention is all the esterified saturated ester from a viewpoint of fully exhibiting the function as a plasticizer.

[Crystal nucleating agent]
The crystal nucleating agent used in the present invention is at least one group selected from an ester group, a hydroxyl group and an amide group in the crystal nucleating agent molecule from the viewpoint of crystallization speed, heat resistance, temperature sensitivity, and transparency. an aliphatic compound having two or more hydroxyl groups have one or more, ester or has aliphatic compound having one or more amide groups is good preferred, hydroxyl two or more, ester or amide group Are more preferable, and aliphatic compounds having two or more hydroxyl groups and two or more ester groups or amide groups are particularly preferable.
The melting point of the crystal nucleating agent is preferably 65 ° C or higher, preferably 70 ° C to 220 ° C, and more preferably 80 to 190 ° C.

  The reason why the effect of the present invention is further improved by the aliphatic compound is not clear, but if it has two or more of the above functional groups, the interaction with the polylactic acid resin becomes good and the compatibility is improved. It is thought that this is due to fine dispersion in the resin, probably having one or more hydroxyl groups, preferably two or more, so that the dispersibility in the polylactic acid resin is improved, and one or more ester groups or amide groups are obtained. It is considered that the compatibility with the polylactic acid resin is preferably improved by having two or more. When the melting point of the crystal nucleating agent is higher than the heat treatment temperature and lower than or equal to the kneading temperature of the resin composition, the dispersibility is improved by dissolving the crystal nucleating agent during kneading. Since the temperature of crystallization and heat treatment can be raised, it is also preferable from the viewpoint of improving the crystallization speed. The preferred crystal nucleating agent is considered to precipitate a large number of fine crystals quickly in the cooling process from the resin melt state, and is also preferable from the viewpoint of improving transparency and crystallization speed.

  Examples of the crystal nucleating agent used in the present invention include aliphatic esters and aliphatic amides. Examples of aliphatic esters include fatty acid esters such as stearic acid monoglyceride and behenic acid monoglyceride, and hydroxy compounds such as 12-hydroxystearic acid triglyceride. Fatty acid esters; aliphatic fatty amides such as hydroxy fatty acid monoamides such as 12-hydroxystearic acid monoethanolamide, aliphatic bisamides such as ethylene bislauric acid amide, ethylene biscapric acid amide, ethylene biscaprylic acid amide, and methylene bis 12-hydroxystearic acid Hydroxy fatty acid bisamides such as acid amide, ethylene bis 12-hydroxy stearic acid amide, hexamethylene bis 12-hydroxy stearic acid amide, and the like. From the viewpoint of moldability, heat resistance, impact resistance, and bloom resistance of the crystal nucleating agent of biodegradable resin molded products, 12-hydroxystearic acid triglyceride, behenic acid monoglyceride, ethylenebis12-hydroxystearic acid amide, hexamethylene Bis 12-hydroxystearic acid amide, 12-hydroxystearic acid monoethanolamide, ethylene biscaprylic acid amide, ethylene biscapric acid amide are preferred, 12-hydroxystearic acid triglyceride, ethyl bis 12-hydroxystearic acid amide, hexamethylene bis 12 -Hydroxystearic acid amide, 12-hydroxystearic acid monoethanolamide are more preferable, 12-hydroxystearic acid triglyceride, ethylene bis 12-hydroxystearic acid Phosphoric acid amide, more preferably hexamethylene bis hydroxystearic acid amide, ethylenebis 12-hydroxystearic acid amide, hexamethylene bis hydroxystearic acid amide are particularly preferred.

  When the crystal nucleating agent of the present invention is added to a transparent biodegradable resin, excellent transparency can be maintained.

[Biodegradable resin composition]
The biodegradable resin composition of the present invention contains a polylactic acid resin, a plasticizer, a crystal nucleating agent, and a hydrolysis inhibitor .

The content of the polylactic acid resin in the biodegradable resin composition of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more from the viewpoint of achieving the object of the present invention.
The content of the plasticizer in the biodegradable resin composition of the present invention is 5 to 70 parts by weight with respect to 100 parts by weight of the polylactic acid resin, from the viewpoint of obtaining a sufficient crystallization speed and impact resistance. 50 parts by weight is more preferable, and 10 to 40 parts by weight is even more preferable.
The content of the crystal nucleating agent in the biodegradable resin composition of the present invention is 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, with respect to 100 parts by weight of the polylactic acid resin. 3 to 3 parts by weight are particularly preferred.

In addition to the above components, the resin composition of the present invention can contain silicates such as talc, smectite, kaolin, mica, montmorillonite, and inorganic compounds such as silica and magnesium oxide. The average particle size of these inorganic compounds is preferably 0.1 to 20 μm, more preferably 0.1 to 10 μm from the viewpoint of dispersibility. Among these inorganic compounds, silicate is preferable and talc is more preferable from the viewpoint of moldability and heat resistance of the biodegradable resin molded product.
The content of these inorganic compounds is preferably 0.1 to 2 parts by weight, more preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the polylactic acid resin, from the viewpoint of sufficient crystallization speed and transparency. .5 to 1.5 parts by weight is particularly preferred. Moreover, from a viewpoint of sufficient crystallization speed, impact resistance, heat resistance, and rigidity, 3 to 50 parts by weight is preferable, 5 to 40 parts by weight is further preferable, and 5 to 30 parts by weight is particularly preferable.

Examples of the hydrolysis inhibitor used in the biodegradable resin composition of the present invention include carbodiimide compounds such as polycarbodiimide compounds and monocarbodiimide compounds, and polycarbodiimide compounds are preferred from the viewpoint of moldability of biodegradable resin molded products. .

  Examples of the polycarbodiimide compound include poly (4,4′-diphenylmethanecarbodiimide), poly (4,4′-dicyclohexylmethanecarbodiimide), poly (1,3,5-triisopropylbenzene) polycarbodiimide, and poly (1,3,5). -Triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide and the like, and examples of the monocarbodiimide compound include N, N'-di-2,6-diisopropylphenylcarbodiimide.

The carbodiimide compounds may be used alone or in combination of two or more in order to satisfy the moldability, heat resistance, impact resistance, and bloom resistance of the crystal nucleating agent of the biodegradable resin molded product. Poly (4,4′-dicyclohexylmethanecarbodiimide) is obtained from carbodilite LA-1 (manufactured by Nisshinbo Co., Ltd.), poly (1,3,5-triisopropylbenzene) polycarbodiimide and poly (1,3,5). -Triisopropylbenzene and 1,5-diisopropylbenzene) polycarbodiimide are stabuxol P and stabuxol P-100 (Rhein Chemie), N, N'-di-2,6-diisopropylphenylcarbodiimide is stabuxol I (Rhein Chemie) Can be purchased and used.
The content of the hydrolysis inhibitor in the biodegradable resin composition of the present invention is preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the polylactic acid resin from the viewpoint of moldability of the biodegradable resin molded product. 0.1 to 2 parts by weight is more preferable.

  In addition to the above, the biodegradable resin composition of the present invention further contains other components such as a hindered phenol or phosphite antioxidant, or a hydrocarbon wax or a lubricant that is an anionic surfactant. can do. The content of each of the antioxidant and the lubricant is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

  The biodegradable resin composition of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an inorganic filler, an antifungal agent, an antibacterial agent and a foaming agent as components other than those described above. In addition, flame retardants and the like can be contained as long as the object of the present invention is not hindered.

[Production method of biodegradable resin molded product]
The method for producing a biodegradable resin molded article of the present invention comprises crystallizing from a sheet or film of the biodegradable resin composition according to the present invention to a relative crystallinity of 80% or more by the above steps (1) and (2). This is a method of obtaining a molded product by making it.

  In the present invention, the biodegradable resin composition sheet or film is prepared by mixing the biodegradable resin composition of the present invention with a twin-screw extruder, a Banbury mixer or the like to prepare a pellet or the like and drying it. It can be obtained by molding using an extrusion molding method or a calendar molding machine.

  In the present invention, the biodegradable resin composition can be mixed by an ordinary method, for example, a method of mixing a crystal nucleating agent and a plasticizer while melting the biodegradable resin using an extruder or the like. Etc. The temperature at the time of mixing is not less than the melting point (Tm1) of the polylactic acid resin from the viewpoint of dispersibility of the crystal nucleating agent and plasticizer, preferably in the range of Tm1 to Tm1 + 100 ° C, more preferably Tm1 to Tm1 + 50 ° C. Range. Specifically, it is preferably 170 to 240 ° C, more preferably 170 to 220 ° C.

  In addition, melting | fusing point (Tm1) of polylactic acid resin is a value calculated | required from the crystal melting endothermic peak temperature by the temperature rising method of differential scanning calorimetry (DSC) based on JIS-K7121.

In the present invention, a method for forming a sheet or film of the biodegradable resin composition (each unstretched) includes a T-die extrusion molding method or a calendar molding method. At that time, the biodegradable resin may be in an amorphous state or a crystalline state, and is not particularly limited when performing the thermoforming process of the present invention in-line, but when used after storing the sheet or film as a roll, From the viewpoints of stability and blocking resistance, it is preferable to crystallize to a relative crystallinity of 30% or more.
The method of crystallization to a relative crystallinity of 30% or more is a T-die extrusion molding method or a calendar molding method. The method of crystallizing the sheet | seat or film which annealed in the thermostatic chamber in the state which does not each overlap is mentioned.

The thickness of the sheet or film of the present invention is appropriately selected depending on the purpose of use. Although there is no clear regulation, the thickness of the sheet is 100 to 2000 μm, and the thickness of the film is 100 μm or less. The thickness is appropriately selected depending on the purpose of use, but is usually preferably 50 to 1000 μm, more preferably 100 to 800 μm. On the other hand, in the case of producing a thermoformed product making use of the transparency of polylactic acid, the haze value of a 0.5 mm thick sheet or film is preferably 50% or less, even 40% or less in a crystallized sheet or film. More preferably, 20% or less is particularly preferable, and 10% or less is most preferable.
The following method 1 is mentioned as a preferable manufacturing method in the present invention.
Method 1: A method in which the heating temperature of the sheet or film in step (1) is Tg or more and less than Tm, and the mold temperature is 60 to 100 ° C. in step (2) .

  In addition, melting | fusing point (Tm) of a biodegradable resin composition is a value calculated | required from the crystal melting endothermic peak temperature by the temperature rising method of differential scanning calorimetry (DSC) based on JIS-K7121. The glass transition temperature (Tg) of the biodegradable resin composition is a value obtained from the peak temperature of the loss elastic modulus (E ″) in the dynamic viscoelasticity measurement of a sheet or film having a crystallinity of 0%. Yes, the value can be obtained from the dynamic viscoelasticity measuring method described in the examples.

  Examples of the heating method in the step (1) of the present invention include a non-contact heating method using radiant heat such as a ceramic heater, and a heating method using hot air or a heating plate. The temperature in the step (1) is the temperature of the sheet or film that is reached immediately before shifting to the step (2) by heating. The time required for the step (1) varies depending on the setting of the heater and the apparatus, but is preferably 1 to 60 seconds, more preferably 2 to 45 seconds, further preferably 3 to 30 seconds, and more preferably 5 to 20 from the viewpoint of productivity. Seconds are particularly preferred.

  The holding time in the mold in the step (2) of the present invention achieves a relative crystallinity of 80% or more, and is preferably 5 to 60 seconds, more preferably 8 to 50 seconds, from the viewpoint of productivity. 10 to 45 seconds are more preferable, and 10 to 40 seconds are particularly preferable.

  About the manufacturing method of this invention, in the case of the method 1, an amorphous or crystallized sheet | seat or film is softened until the softness | flexibility which can follow a metal mold | die is obtained by heat processing, and between a sheet | seat or film and a metal mold | die. Next, after applying a vacuum and / or compressed air, or after extending the pressure by assisting with a plug to some extent, the vacuum and / or compressed air is used to follow the mold, and it is placed in the mold at a temperature suitable for crystallization. A molded article that is held and crystallized (relative crystallinity of 80% or more) is obtained. When using a sheet or film having a relative crystallinity of less than 30%, the method 1 is usually used for crystallization in a mold. In that case, any molding method can be applied. On the other hand, from the viewpoint of improving the molding speed (productivity) and transparency, it is preferable to use a sheet or film crystallized in advance to a relative crystallinity of 30% or more. When maintaining the transparency of the molded body, the transparency of the sheet or film crystallized in advance is preferably 50% or less, more preferably 40% or less, and the haze value of the 0.5 mm thick sheet or film, 20% or less is particularly preferable, and 10% or less is most preferable. In this case, any molding method can be applied, but when manufacturing a molded product having a deep drawing, a complicated shape transfer with high design, a fitting part, etc., in vacuum molding with a molding pressure of 0.1 MPa or less. In some cases, a satisfactory molded product cannot be obtained, and a pressure forming method that increases the forming pressure is preferable, and a plug assist method is more preferable.

  When the biodegradable resin is polylactic acid, in the method 1 of the present invention, the heating temperature in the step (1) satisfies the relative crystallinity of 80% from the viewpoints of moldability, prevention of uneven thickness, and appearance improvement. When forming a non-sheet or film, 40 to 140 ° C is preferable, 50 to 120 ° C is more preferable, and 60 to 100 ° C is particularly preferable. Moreover, when shape | molding a sheet | seat or film with a relative crystallinity degree of 80% or more, 80 degreeC or more and less than 165 degreeC are preferable, 90-160 degreeC is further more preferable, and 100-150 degreeC is especially preferable. On the other hand, the mold temperature in the step (2) is preferably 60 to 100 ° C, more preferably 65 to 95 ° C, particularly preferably 70 to 90 ° C, from the viewpoint of transparency and moldability (molding speed). Most preferred is 85 ° C.

  Examples of the thermoforming in the step (2) of the present invention include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a thermo forming method with plug assist added thereto, a matched mold forming method, and the like. A pressure forming method and a vacuum pressure forming method are preferred.

  In the production method of the present invention, a molded product crystallized to a relative crystallinity of 80% or more, preferably 90% or more, more preferably 95% or more by the steps (1) and (2) as described above. Obtainable.

  In the present invention, the relative crystallinity refers to the crystallinity represented by the following formula. In the following formula, the treatment at 70 ° C. × 60 hours indicates a treatment in which a molded product immediately after molding is left in a temperature-controlled room controlled at 70 ° C. for 60 hours and then allowed to cool at room temperature (preferably 25 ° C.).

  Relative crystallinity (%) = (crystallinity immediately after molding (%)) / (crystallinity after 70 ° C. × 60 hours treatment (%)) × 100

  The reason for prescribing the crystallinity after molding as described above is that the effect of the present invention is exhibited by crystallization of the base resin, heat resistance, temperature sensitivity, blocking resistance, solvent resistance. This is because the improvement in properties and the like is also an effect of crystallization. In addition, the improvement in flexibility (decrease in elastic modulus and improvement in elongation at break) and the improvement in impact resistance by the plasticizer can be sufficiently effective by crystallization.

Examples 1 and 2 and Comparative Examples 1 to 5
The present invention products (A to B) and comparative products (C to D) shown in Table 1 as biodegradable resin compositions were used in a biaxial extruder (Berstorf ZE40A), and the cylinder and die temperatures were 190 to The mixture was melt-kneaded under conditions of 180 ° C. to obtain resin composition pellets.

  The obtained pellets were dried at 70 ° C. under reduced pressure for 1 day, and the water content was adjusted to 500 ppm or less. Using the pellets, a sheet shown in Table 2 was obtained with a T-die extruder (250 mm T die manufactured by Soken Co., Ltd.). After the obtained sheet was softened by heat treatment (step (1)) under the conditions shown in Table 3, it was changed to Table 3 using a Sanwa Kogyo vacuum forming machine (see FIG. 1 for the mold). Vacuum molding (step (2)) was performed under the conditions shown to obtain a molded product.

Table 3 shows the moldability of each resin composition and the crystallinity and transparency evaluation results of the obtained molded product measured by the following method. Incidentally, in the column of molding of Table 3, the method 1, means a method 1 described in the above section [biodegradable resin molded article production method.
Further, the molded products obtained in Examples 1 and 2 and Comparative Examples 2, 4, and 5 were tested for blocking resistance, heat resistance, flexibility / temperature sensitivity / heat resistance, impact resistance and bleed resistance by the following methods. Measured with These results are shown in Table 4.

<Crystallinity>
A sample is cut out from the bottom plane of the obtained sheet or molded product, and using a wide-angle X-ray diffraction measurement device (RINT2500VPC, light source CuKα, tube voltage 40 kV, tube current 120 mA manufactured by Rigaku Corporation), 2θ = 5-30 ° The crystallinity was determined by analyzing the amorphous and crystalline peak areas.

<Transparency>
A sample was cut out from the bottom plane of the obtained sheet or molded product, and the haze value was measured using an integrating sphere light transmittance measuring device (haze meter) defined in JIS-K7105. Smaller numbers indicate better transparency.

<Blocking resistance>
Ten pieces of the obtained molded articles were placed in an oven controlled at 80 ° C. and treated for 4 hours, allowed to cool at room temperature, a sample peel test was performed, and the following criteria were evaluated.
○: The samples peel easily without sticking to each other.
X: The samples stick to each other and cannot be peeled off.
<Heat resistance>
The obtained molded product was filled with 80% hot water at 80% capacity, and the degree of deformation was visually observed.
○: Deformation is not seen at all.
X: Deformation occurs.
XX: Deforms greatly.

<Flexibility, temperature sensitivity, heat resistance>
A sample is cut out from the flat portion of the obtained molded product, and based on JIS-K7198, using a dynamic viscoelasticity measuring device (DVA-200 manufactured by IT Measurement Control) at a frequency of 50 Hz and a temperature rising rate of 2 ° C./min. The temperature dependence of the storage elastic modulus (E ′) in the temperature range of −20 ° C. to 150 ° C. and the storage elastic modulus (E ′) at 0 ° C., 25 ° C. and 60 ° C. were measured.

<Impact resistance>
The corner of the bottom of the molded product was impacted with a hammer and the impact resistance was observed.
○: Not cracked at all ×: Breakage or cracks occur.
<Bleed resistance>
The obtained molded article was left in a thermostatic chamber at 70 ° C. for one week, and the presence or absence of a plasticizer bleed on the surface was observed with the naked eye.

* 1: Polylactic acid resin (manufactured by Mitsui Chemicals, LACEA H-400)
* 2: Plasticizer Diester of succinic acid and triethylene glycol monomethyl ether * 3: Crystal nucleating agent Ethylene bis 12-hydroxystearic acid amide (Nihon Kasei Co., Ltd., SLIPAX H)
* 4: Hydrolysis inhibitor polycarbodiimide (Nisshinbo Co., Ltd., Carbodilite LA-1)
* 5: Nihon Talc Co., Ltd., Micro Ace P-6
* 6: Stearic acid monoamide (manufactured by Kao Corporation, fatty acid amide S)
* 7: Tributyl acetylcitrate (ATBC, manufactured by Taoka Chemical Co., Ltd.)

It is a figure which shows the metal mold | die used in the Example, (A) is a top view, (B) is the sectional view on the a-a 'line.

Claims (2)

A polylactic acid resin, a plasticizer comprising a compound having 2 or more ester groups in the molecule and an average added mole number of ethylene oxide of 2 to 9, and an ester group, a hydroxyl group and an amide group in the molecule are selected. A crystal nucleating agent composed of an aliphatic compound having at least two groups of at least one kind and a hydrolysis inhibitor, and a plasticizer content of 5 to 70 parts by weight with respect to 100 parts by weight of a polylactic acid resin. A method for producing a biodegradable resin molded article, in which a sheet or film made of a biodegradable resin composition having an agent content of 0.1 to 5 parts by weight is thermoformed, comprising the following steps (1) and ( A method for producing a biodegradable resin molded product, which obtains a molded product crystallized to a relative crystallinity of 80% or more by 2)
Step (1): heat the sheet or film made of a biodegradable resin composition, to a temperature below the melting point (Tm) of the glass transition temperature (Tg) of more biodegradable resin composition of the biodegradable resin composition Engineering as step (2): step a sheet or film obtained in (1), at a mold temperature of 60 to 100 [° C., the step of thermoforming   The method for producing a biodegradable resin molded article according to claim 1, wherein the thermoforming in the step (2) is vacuum forming, pressure forming or vacuum pressure forming.

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