JP4800348B2 - Manufacturing method of biodegradable resin molded products. - Google Patents

Description

  The present invention relates to a method for producing a biodegradable resin molded article and a biodegradable resin molded article obtained by the 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, in the case of polylactic acid resin, it is brittle, hard, and lacks flexibility, all of which are limited to the field of hard molded products. When molded into a film, the flexibility is insufficient, or whitening occurs when bent. The present 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.

  Various techniques for applying a polylactic acid resin to soft and semi-rigid fields have been proposed, such as a method of adding a plasticizer or a method of crystallizing by adding a crystal nucleating agent to improve heat resistance. Patent Document 1 is characterized in 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, A method for producing an aliphatic polyester molded article having both properties and crystallinity is disclosed. 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.

General-purpose resins such as polyolefin have a high crystallization speed and good processability, so they can be extruded, but biodegradable resins such as polylactic acid have a low crystallization speed and can be extruded. The current situation is not done.
When crystallization is performed when the resin composition described in Patent Documents 1 and 2 is formed into a sheet or film by an extruder, the crystallization requires heating to a temperature higher than the glass transition point of the resin composition. Since the resin composition described in these patent documents has a low crystallization rate, it cannot be crystallized on the roll surface and remains in an amorphous state, so that it does not peel off due to sticking to the roll, forcing it with tension. Since there is no stiffness when peeled, there is a problem that the sheet or film is easily deformed, and continuous production of the crystallized sheet or film by extrusion molding has not been possible.
Japanese Patent No. 3411168 International Publication No. 2003/042302 Pamphlet

  The subject of this invention is providing the method of manufacturing the sheet | seat and film of biodegradable resin with favorable softness | flexibility, heat resistance, and temperature sensitivity with high productivity by an extrusion method.

  The present invention relates to a method for producing a biodegradable resin molded article for forming a sheet or film from a resin composition containing a polylactic acid resin, a plasticizer, and a crystal nucleating agent. The relative crystallinity is obtained by a method comprising the step of contacting a sheet or film extruded from two or more metal rolls having a surface temperature of 60 to 100 ° C. and / or further heat-treating through a constant temperature layer of 60 to 100 ° C. Provided are a method for producing a biodegradable resin molded article obtained by crystallization to 30% or more to obtain a sheet or film, and a biodegradable resin molded article obtained by this production method.

  Production of biodegradable resin sheets and films having a relative crystallinity of 30% or more and excellent in flexibility, temperature sensitivity and heat resistance by the production method of the biodegradable resin molded article of the present invention with high productivity. Furthermore, when applied to a transparent biodegradable resin, excellent transparency can be maintained.

[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-lactide. 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 commercially available polylactic acid resins include Mitsui Chemicals, Inc., trade name Lacia series; Nature Works, trade name Nature works series; Toyota Motor Corporation, U'z series, 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]
The plasticizer used in the present invention is not particularly limited, and examples thereof include plasticizers used in general biodegradable resins. The plasticizer has two or more ester groups in the molecule and has an average addition mole of ethylene oxide. Compounds having 2 to 9, especially 3 to 9 are preferred. 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 JIS K0070 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. Are preferably aliphatic compounds having one or more hydroxyl groups, more preferably aliphatic compounds having one or more ester groups or amide groups, two or more hydroxyl groups, and ester groups or amide groups. An aliphatic compound having one or more is more preferable, and an aliphatic compound having two or more hydroxyl groups and two or more ester groups or amide groups is 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 crystallization and heat treatment temperature can be increased, it is 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, and a crystal nucleating agent.

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 preferably 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 preferably 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 contains silicates such as talc, smectite, kaolin, mica, montmorillonite, inorganic compounds such as silica, magnesium oxide, calcium carbonate, magnesium hydroxide, and aluminum hydroxide. can do. 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, and particularly preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the polylactic acid resin. .

  The biodegradable resin composition of the present invention can further contain a hydrolysis inhibitor in addition to the crystal nucleating agent and the plasticizer. Examples of the hydrolysis inhibitor 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 (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, as components other than those described above, biodegradable resins other than polylactic acid resins, antistatic agents, antifogging agents, light stabilizers, ultraviolet absorbers, pigments, and inorganic fillers. An antifungal agent, an antibacterial agent, a foaming agent, a flame retardant, and the like can be contained within a range that does not hinder achievement of the object of the present invention.

[Production method of biodegradable resin molded product]
The method for producing a biodegradable resin molded article of the present invention is a method of producing a biodegradable resin composition according to the present invention by subjecting a sheet or film extruded from a die by an extrusion molding method to two surface temperatures of 60 to 100 ° C. It is a method of obtaining a sheet or film by crystallization to a relative crystallinity of 30% or more by a method including a step of contacting the metal roll and / or further heat-treating through a constant temperature layer of 60 to 100 ° C.

  In the present invention, as an extrusion molding method, the biodegradable resin composition of the present invention is mixed with a twin screw extruder, a pressure kneader or the like to prepare a pellet or the like, and after drying, the sheet or the Examples include a method of forming into a film or mixing with an extruder and then directly forming into a sheet or film.

  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 a polylactic acid resin using an extruder or the like. Is mentioned. The mixing temperature is preferably at least the melting point (Tm) of the polylactic acid resin from the viewpoint of dispersibility of the crystal nucleating agent and plasticizer, more preferably in the range of Tm to Tm + 100 ° C., and still more preferably Tm to Tm + 50. It is in the range of ° C. Specifically, it is preferably 170 to 240 ° C, more preferably 170 to 220 ° C.

  In addition, melting | fusing point (Tm) of a 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 method of the present invention, a group of metal rolls with which a sheet or film extruded from a die first comes into contact is referred to as a first roll. One or more metal rolls may serve as the first roll. In the method of the present invention, the surface temperature of the first roll is controlled to 60 to 100 ° C. to crystallize to the extent that the sheet shape is maintained and the roll peelability is improved, and thereafter the metal roll (heat treated roll) In this method, the surface temperature or the temperature of the thermostat is set to 60 to 100 ° C., and the relative crystallinity is 30% or more.

In the method of the present invention, from the viewpoint of crystallization speed and productivity, the surface temperature of the first roll is preferably 60 to 90 ° C., the surface temperature of the heat treatment roll or the temperature of the thermostatic bath is more preferably 70 to 90 ° C., The surface temperature of the roll is 65 to 85 ° C, the surface temperature of the heat treatment roll or the temperature of the thermostat is more preferably 70 to 90 ° C, the surface temperature of the first roll is 70 to 80 ° C, the surface temperature of the heat treatment roll or the temperature of the thermostat The temperature is particularly preferably 75 to 85 ° C. Moreover, 1 or 2 or more heat processing rolls may be sufficient, and the sum total of the time for which a sheet | seat and a film are contacting the 1st roll and the heat processing roll is preferable, 5 to 60 second is more preferable, and 8 to 45 second is more preferable. 30 seconds is particularly preferred.
In the method of the present invention, it is preferable that the relationship between the surface temperatures of the first roll and the heat treatment roll is represented by the following formula from the viewpoint of transparency.

(Heat treatment roll surface temperature-20 ° C) ≤ (first roll surface temperature) ≤ (heat treatment roll surface temperature)

  More preferably (heat treatment roll surface temperature -15 ° C) ≤ (first roll surface temperature) ≤ (heat treatment roll surface temperature -5 ° C), particularly preferably (heat treatment roll surface temperature -10 ° C) ≤ (first roll surface temperature) ) ≦ (heat treatment roll surface temperature−5 ° C.). Specifically, the heat treatment roll surface temperature is 70 ° C to 90 ° C, the first roll surface temperature is preferably 60 to 90 ° C, more preferably 65 to 85 ° C, and particularly preferably 70 to 85 ° C.

  In the production method of the present invention, the relative crystallinity of the molded product is 30% or more, preferably 45% or more, more preferably 80% or more, from the viewpoint of blocking resistance and heat resistance, by the method described above. More preferably, a molded body crystallized to 90% or more, particularly preferably 95% or more can be obtained.

  In the present invention, the relative crystallinity refers to the crystallinity represented by the following formula. In the following formula, “70 ° C. × 60 hour treatment” refers to a treatment in which a sheet 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.

  The production method of the present invention makes it possible to form a crystallized sheet from the resin composition of the present invention with high productivity using a normal T-die extrusion molding machine without a stretching step. Specifically, productivity here means high forming speed, extremely few troubles such as adhesion to metal rolls, uneven thickness, wrinkles, etc., and annealing treatment (post heat treatment process) in another facility after sheet forming It means that in-line molding that is not necessary is possible.

[Biodegradable resin molded products]
The sheet of the present invention formed by the production method of the present invention is excellent in transparency because it can be crystallized with high transparency, and the solvent resistance is remarkably improved by crystallization. In addition, the sheet which is the biodegradable resin molded product of the present invention can significantly improve the scratch resistance as compared with the unmodified polylactic acid or polyethylene terephthalate sheet due to the effect of flexibility and additives, Due to the improved property, it is resistant to both printing inks and most solvents, thus expanding adaptability. In addition, the sheet of the present invention does not cause warping (curling phenomenon) caused by the solvent of the ink that occurs when the printed material just after printing as seen in a polypropylene clear holder is brought into contact, and has scratch resistance and transparency. Since it is high, it is also suitable as a base sheet for a clear holder.

  Further, since the sheet formed by the production method of the present invention has a high crystallization speed, it is suitable as a sheet for thermoforming performed by secondary processing such as vacuum forming and pressure forming, and is particularly a heat-resistant container utilizing transparency. It can be used for products such as blister packs and trays.

  The biodegradable resin compositions used in the following examples and comparative examples are collectively shown in Table 1.

* 1: Polylactic acid resin (manufactured by Mitsui Chemicals, LACEA H-400)
* 2: Triacetate ester of 6 mol adduct of glycerin with ethylene oxide * 3: Ethylene bis 12-hydroxystearic acid amide (Nippon Kasei Co., Ltd., SLIPAX H)
* 4: 12-hydroxystearic acid triglyceride (manufactured by Kao Corporation, Kao Wax 85P)
* 5: Diester of succinic acid and triethylene glycol monomethyl ether * 6: Polycarbodiimide (Nisshinbo Co., Ltd., Carbodilite LA-1)
* 7: Nihon Talc Co., Ltd., Micro Ace P-6
* 8: Stearic acid monoamide (manufactured by Kao Corporation, fatty acid amide S)
* 9: Tributyl acetyl citrate (ATBC manufactured by Taoka Chemical Industry Co., Ltd.)

Examples 1-3, Comparative Examples 1-4
Using the biaxial extruder (Berstorf ZE40A) as the biodegradable resin composition of the present invention products (A to B) and comparative products (EF) shown in Table 1, the cylinder and die temperatures are 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.
The pellet was brought into contact with the first roll controlled to the surface temperature shown in Table 2 with a T-die extruder (UT-32-T 200 mmT die manufactured by Plastic Engineering Laboratory), and the heat treatment roll having the surface temperature shown in Table 2 To obtain a film (the roll unit is composed of a first roll and three heat treatment rolls, each of which can be controlled with cold water or hot water).

Table 2 shows the moldability of each resin composition and the evaluation results of the degree of crystallinity, transparency, and blocking resistance measured by the following method for the obtained film.
Further, the flexibility, temperature sensitivity, heat resistance, and bleed resistance of the films obtained in Example 3 and Comparative Examples 3 and 4 were evaluated by the following methods. These results are shown in Table 3.

<Crystallinity>
Using the wide-angle X-ray diffractometer (RINT2500VPC manufactured by Rigaku Corporation, light source CuKα, tube voltage 40kV, tube current 120mA) for the film after molding, the amorphous and crystalline peak areas in the range of 2θ = 5-30 ° The crystallinity was determined by analysis.

<Transparency>
About the film after shaping | molding, the haze value was measured using the integrating sphere type light transmittance measuring apparatus (haze meter) prescribed | regulated to JIS-K7105. Smaller numbers indicate better transparency.

<Blocking resistance>
The film after molding is cut into a size of 6 cm in length and 6 cm in width, and the two samples are bonded together and sandwiched between two 10 cm × 10 cm × 5 mm thick glass plates, and a weight of 1 kg is applied from above the glass, The sample was placed in an oven controlled at 80 ° C., treated for 4 hours, and allowed to cool at room temperature, and then a sample peel test was performed and evaluated according to the following criteria.
○: The samples peel easily without sticking to each other.
X: The samples stick to each other and cannot be peeled off.

<Flexibility, temperature sensitivity, heat resistance>
About the film after shaping | molding, based on JIS-K7198, with a dynamic viscoelasticity measuring apparatus (DVA-200 made by IT measurement control), 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 region and the storage elastic modulus (E ′) at 0 ° C., 25 ° C., 60 ° C. and 80 ° C. were measured.
The lower the E ′ value at 25 ° C., the higher the flexibility. The lower the change in E ′ in the temperature range of 0 ° C. to 80 ° C., the better. The heat resistance is 60 ° C. or 80 ° C. The value of E 'was judged.

<Bleed resistance>
The molded film (length 100 mm × width 100 mm) was left in a thermostatic chamber at 70 ° C. for 1 week, and the presence or absence of a plasticizer bleed on the surface was observed with the naked eye.

  As shown in Table 2, the resin composition of the present invention was subjected to T-die extrusion molding according to the molding method of the present invention. As a result, the moldability of the film from each metal roll was satisfactory and the moldability was good. As shown, a crystallized film having a relative crystallinity of 30% or more was obtained in a short heat treatment time, and crystallization with excellent transparency was maintained.

  On the other hand, in the case of the resin composition of the comparative example, since it was not crystallized by the first roll, it adhered to the film at this point and could not be molded. Therefore, film formation was possible under the conditions of Comparative Examples 3 to 4 not corresponding to the production method of the present invention, but the film was in an amorphous state.

In addition, in the evaluation of blocking resistance assuming storage stability when the film is stocked in a roll, all the examples of the present invention have good blocking resistance, but the amorphous sheet of the comparative example caused blocking. Oops.
Even in the case of the resin composition of the present invention, if the first roll or the heat-treated roll exceeds 100 ° C., the tension of the film is remarkably lowered when the amorphous film is brought into contact with the roll, resulting in uneven contact. If the heat treatment roll becomes uniform and the heat treatment roll is lower than 60 ° C., the crystallization speed is remarkably lowered, so that crystallization does not proceed, and if it is Tg or more and less than 60 ° C., a problem of sticking to the heat treatment roll may occur.

  As shown in Table 3, the storage elastic modulus E ′ at 0 ° C. and 25 ° C. of the films shown in the examples of the present invention was lower than that of Comparative Example 3 containing no plasticizer, and the flexibility was improved. In addition, the sheet of the example has a small change in E ′ from 0 ° C. to 80 ° C. and is excellent in temperature sensitivity and heat resistance, whereas Comparative Examples 3 and 4 which are in an amorphous state are 60 ° C. and 80 ° C., respectively. E 'suddenly decreased at 0 ° C, resulting in poor temperature sensitivity and heat resistance. In addition, as a result of evaluating the bleed resistance, the resin composition of the present invention is excellent in bleed resistance, whereas the resin composition of Comparative Example 4 shows a bleed phenomenon in an accelerated test by heat treatment. It became inferior result.

Examples 4-9, Comparative Examples 5-8
The present invention products (C to D) and comparative products (E to F) shown in Table 1 as biodegradable resin compositions were used in a twin-screw 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.
The pellet was brought into contact with the first roll controlled to the surface temperature shown in Table 4 with a T-die extruder (250 mm T die manufactured by Soken Co., Ltd.), and heat-treated with a heat treatment roll having the surface temperature shown in Table 4, A film was obtained (the roll unit was composed of a first roll and one heat treatment roll, and temperature control was possible with oil or hot water, respectively).

  The moldability of each resin composition and the evaluation of the degree of crystallinity, transparency, and blocking resistance of the obtained sheet were performed in the same manner as described above. The results are shown in Table 4.

Further, the flexibility, temperature sensitivity, heat resistance, and bleed resistance of the sheets obtained in Examples 5 and 8 and Comparative Examples 7 and 8 were evaluated in the same manner as described above. Moreover, the tensile property was measured by the following method. These results are shown in Table 5.
Further, the solvent resistance of the sheets obtained in Examples 5 and 8 and Comparative Examples 7 and 8 and the PET sheet (polyethylene terephthalate sheet, sheet thickness 200 μm) was evaluated by the following method. These results are shown in Table 6.
Further, the scratch resistance of the sheets obtained in Examples 5 and 8 and Comparative Examples 7 and 8 and the PET sheet was evaluated by the following method. These results are shown in Table 7.

<Tensile properties>
Each sheet was punched with a No. 3 dumbbell, left in a thermostatic chamber at room temperature of 23 ° C. and a humidity of 60% for 24 hours, and subjected to a tensile test at a tensilon tensile speed of 50 mm / min to measure the tensile modulus and elongation at break.

<Solvent resistance>
Each sheet was immersed in each solvent shown in Table 6 adjusted to 25 ° C. for 30 seconds, taken out, then naturally dried, the state of each sheet was observed with the naked eye, and evaluated according to the following criteria.
○: No change in gloss, transparency, and surface condition Δ: Gloss is lowered and the surface is rough.
X: Transparency decreases.
XX: Dissolves.

<Scratch resistance>
Each sheet was fixed on a horizontal base, and based on JIS-K5600-5-4, the surface of the sheet was scratched with a pencil core having various hardnesses shown in Table 7, and scratch resistance was evaluated according to the following criteria.
○: Not scratched ×: Scratched

<180 ° bending whitening>
Each sheet was allowed to stand in a temperature-controlled room controlled at 25 ° C. for 24 hours, then folded 180 °, the state of the sheet was observed with the naked eye, and the folding whitening property was evaluated according to the following criteria.
○: Whitening does not occur.
Δ: Slight white streaks appear.
X: Vigorously whitened.

  As shown in Table 4, the resin composition of the present invention was subjected to T-die extrusion molding by the molding method of the present invention. As a result, the moldability of the sheet from each metal roll was satisfactory and the moldability was good. As shown in FIG. 4, a crystallization sheet having a relative crystallinity of 30% or more was obtained in a short heat treatment time, and the crystallization while maintaining excellent transparency in Examples 4 to 6 was also achieved.

  On the other hand, in the case of the resin composition of the comparative example, since it was not crystallized by the first roll, the sheet was stuck at this point and could not be molded. Therefore, sheet molding was possible under the conditions of Comparative Examples 7 and 8 that did not correspond to the production method of the present invention, but the sheet was in an amorphous state.

  In addition, in the evaluation of blocking resistance assuming storage stability when sheets are stocked in a roll, all of the examples of the present invention have good blocking resistance, but the amorphous sheets of Comparative Examples 7 and 8 are blocking. I have caused.

  Even in the case of the resin composition of the present invention, if the first roll or the heat-treated roll exceeds 100 ° C., the tension of the film is remarkably lowered at the time when the amorphous sheet is brought into contact with the roll, resulting in uneven contact. If the heat treatment roll becomes uniform and the heat treatment roll is lower than 60 ° C., the crystallization speed is remarkably lowered, so that crystallization does not proceed, and if it is Tg or more and less than 60 ° C., a problem of sticking to the heat treatment roll may occur.

  As shown in Table 5, the storage elastic modulus E ′ at 0 ° C. and 25 ° C. of the sheet shown in the examples of the present invention was lower than that of Comparative Example 7 containing no plasticizer, and the flexibility was improved. Further, the sheet of the example has a small change in E ′ from 0 ° C. to 80 ° C. and is excellent in temperature sensitivity and heat resistance, whereas Comparative Examples 7 and 8 which are in an amorphous state are 60 ° C. and 80 ° C., respectively. E 'suddenly decreased at 0 ° C, resulting in poor temperature sensitivity and heat resistance.

Further, when measuring the commonly used tensile physical properties, the sheet of the example has a low elastic modulus, a remarkably high elongation at break, and excellent flexibility as compared with Comparative Example 8 which also contains a plasticizer. . It turns out that the effect of a plasticizer is fully exhibited by crystallizing like an Example.
On the other hand, as a result of evaluating the bleed resistance, the resin composition of the present invention is excellent in bleed resistance, whereas the resin composition of Comparative Example 8 shows a bleed phenomenon in an accelerated test by heat treatment. It became inferior result.

  As shown in Table 6, the polylactic acid-based sheet of the comparative example was significantly inferior in solvent resistance. On the other hand, the sheet of the example was remarkably excellent in solvent resistance, and the result was better than that of the PET sheet. This result is considered to be the effect of improving the solvent resistance by crystallization of polylactic acid.

  As shown in Table 7, the sheet of the example was significantly superior in scratch resistance compared to the sheet of the comparative example. This result is thought to be mainly due to the excellent flexibility of the sheets of the examples, but there is a possibility that polylactic acid crystallization and crystal nucleating agents have some modification effect on the sheet surface. Is also possible.

Claims (5)

From a resin composition containing a polylactic acid resin, a plasticizer, and a crystal nucleating agent selected from an aliphatic compound having one or more hydroxyl groups in the molecule and one or more ester groups or amide groups, film a method for producing a biodegradable resin molded article for molding the, by extrusion, sheet or film extruded from the die is contacted with two or more metal roll surface temperature of 60 to 100 [° C. step A method for producing a biodegradable resin molded article, in which a sheet or film is obtained by crystallization to a relative crystallinity of 30% or more by a method comprising: From a resin composition containing a polylactic acid resin, a plasticizer, and a crystal nucleating agent selected from an aliphatic compound having one or more hydroxyl groups in the molecule and one or more ester groups or amide groups, A method for producing a biodegradable resin molded article for forming a film, wherein a sheet or film extruded from a die is brought into contact with two or more metal rolls having a surface temperature of 60 to 100 ° C. by an extrusion method, A method for producing a biodegradable resin molded article, wherein a sheet or film is obtained by crystallization to a relative crystallinity of 30% or more by a method comprising a heat treatment through a constant temperature layer at 60 to 100 ° C. The biodegradable resin molding according to claim 1 or 2 , wherein the content of the plasticizer is 5 to 70 parts by weight and the content of the crystal nucleating agent is 0.1 to 5 parts by weight with respect to 100 parts by weight of the polylactic acid resin. Product manufacturing method. The method for producing a biodegradable resin molded article according to any one of claims 1 to 3 , wherein the plasticizer is a compound having 2 or more ester groups in the molecule and an average addition mole number of ethylene oxide of 2 to 9. .   A biodegradable resin molded product obtained by the production method according to claim 1.