JP4457656B2 - Injection molded container with excellent biodegradability, heat resistance and impact resistance and its production method - Google Patents

Description

  The present invention relates to an injection-molded container excellent in heat resistance and impact resistance and a method for producing the same, and more particularly has biodegradability and also exhibits excellent heat resistance when used for high temperature filling, The present invention relates to an injection molded container excellent in impact resistance and flavor and a method for producing the same.

As an ideal solution for plastic waste, degradable plastics that have disappeared in the natural environment have attracted attention. Among them, biodegradable plastics that have been destroyed by the action of enzymes released from the body by bacteria and fungi have been used. Yes.
Such biodegradable plastic injection-molded products are also applied to packaging containers, structural members of home appliances, automobile parts, and the like.
However, although this biodegradable plastic is excellent in terms of harmony with the environment, such as biodegradability, in applications of actual plastic molded products such as packaging containers, home appliances, and automobile parts, it has heat resistance and mechanical properties. There are also problems such as strength that must still be improved.

For this reason, various properties are improved by blending various materials with the biodegradable resin.
For example, as a technique for improving heat resistance, a polylactic acid polymer and poly-ε-caprolactone are mixed so that the L-lactic acid ratio is 75% by weight, and the composition contains SiO ₂ 50% or more. A method has been proposed in which inorganic powder is mixed and melted, filled in a heated mold at 85 to 125 ° C., and molded while crystallizing (Patent Document 1).
Similarly, as a technique for improving heat resistance, elasticity is obtained by subjecting a molded product made of polylactic acid or the like to aging under a humidification condition at a temperature of 15 ° C. or more and a relative humidity of 60% or more from the glass transition temperature of polylactic acid. A method for improving heat resistance based on the improvement of the rate has been proposed (Patent Document 2).

JP-A-8-193165 JP 2002-88161 A

  However, in the method of forming while crystallizing in the mold as described in Patent Document 1, the time (cooling time) for crystallization in the mold varies depending on the thickness and shape, and the cooling mold is There is a drawback that the molding cycle requires a longer time than the normal injection molding cycle used. In fact, in molding with a cooling time of 100 seconds, the heat resistance (elastic modulus) of the molded product is improved, but the resin stays in the injection molding machine for a long time, causing thermal decomposition of the resin, and the resin to the mold. Problems such as adhesion of odor and increase in odor components will occur.

  In addition, in the method described in Patent Document 2, it is confirmed that the heat resistance (elastic modulus) is improved in the resin composition mainly composed of lactic acid. However, in the injection molded product made of homo L-lactic acid resin, Since shrinkage and crystal whitening occur, the practicality as a molded article is poor, and even when a resin composition comprising a polylactic acid resin and a biodegradable polyester resin other than polylactic acid resin is subjected to aging treatment under warming and humidifying conditions, There are problems in terms of material strength such as poor impact resistance and easy cracking when dropped.

The present inventors have also proposed a biodegradable resin composition comprising a soft biodegradable polyester resin and a hard biodegradable aliphatic polyester resin. In a molded product comprising such a resin composition, biodegradation is proposed. However, it is desired to obtain an injection-molded product having more excellent mold releasability, although it is possible to obtain high performance and excellent flexibility and impact resistance (Japanese Patent Application No. 2002-301257).
Furthermore, in an injection molded product using an aliphatic polyester resin mainly composed of lactic acid, an odor component derived from lactic acid is generated. It is also necessary to suppress the decrease.
Accordingly, an object of the present invention is to produce an injection molded product having mechanical strength such as heat resistance and impact resistance, in particular, in addition to the above characteristics, it has biodegradability and an odor component generated during injection molding is removed. It is to provide a method for producing an injection molded product.
Another object of the present invention is an injection-molded article having mechanical strength such as heat resistance and impact resistance capable of withstanding high temperature filling, particularly biodegradability and excellent flavor as well as the above characteristics. It is to provide an injection molded product.

According to the present invention, a hard aliphatic polyester resin (A), an aliphatic polyester resin (B) other than the hard polyester resin (A), an aromatic carboxylic acid component and an aliphatic carboxylic acid component as acid components. Ri consists polyester Erasuma containing (C), the hard aliphatic polyester resin (a) and 35 wt% or more, the aliphatic polyester resin (B) 5 to 60 wt%, polyester elastomer (C) 1 the resin composition you in an amount of 30 wt%, the hard aliphatic polyester resin (a) glass transition temperature (Tg) of below the temperature of the mold, mold preferably at a temperature of 10 ° C. to 40 ° C. A method for producing an injection-molded container for high-temperature filling is provided, which is characterized in that after being injection-molded using a heat treatment, heat treatment is performed outside the mold.

In the production method of the injection molded container of the present invention,
1. An inorganic filler, preferably containing an inorganic filler containing 50% by weight or more of SiO ₂ in an amount of 1 to 40 parts by weight per 100 parts by weight of the resin composition;
2. The polyester elastomer (C) is polybutylene terephthalate adipate or polyethylene terephthalate adipate;
3. The hard aliphatic polyester resin (A) is a resin mainly composed of polylactic acid,
4). The aliphatic polyester resin (B) is polybutylene succinate or polyethylene succinate;
5. The difference in thermal shrinkage between the injection molded containers before and after the heat treatment is 5% or less,
6). That the heat treatment is performed under wet heat conditions, in particular, heat treatment of hot water of 70 ° C. or higher, a steam tunnel of 70 ° C. or higher, or an autoclave of 70 ° C. or higher;
7). It is preferred heat treatment is due to dry heat treatment above 70 ° C..
Furthermore, according to the present invention, there is provided an injection molded container for high temperature filling formed by the above production method.

According to the present invention, a resin composition comprising a hard aliphatic polyester resin (A), an aliphatic polyester resin (B) other than the hard polyester resin (A), and a soft polyester resin (C) is obtained. After the injection molding is performed using a mold having a temperature of the aliphatic polyester resin (A) not higher than the glass transition temperature (Tg), preferably a mold having a temperature of 10 to 40 ° C., heat treatment is performed outside the mold. Injection molding containers with excellent moldability and impact resistance can be molded with good moldability (releasability), and heat treatment performed outside the mold under wet heat conditions to reduce container odor derived from polylactic acid In addition, it is possible to provide an injection-molded container with significantly improved flavor. In particular, the soft polyester resin (C) can have excellent biodegradability by using a biodegradable resin.
Since the injection-molded container obtained by the present invention has excellent heat resistance, it can be suitably used for high temperature filling applications.

  In the method for producing an injection-molded container of the present invention, it comprises a hard aliphatic polyester resin (A), an aliphatic polyester resin (B) other than the hard aliphatic polyester resin (A), and a soft polyester resin (C). Use a resin composition or a resin composition further containing an inorganic filler, and mold the resin composition at a temperature not higher than the glass transition temperature (Tg) of the hard aliphatic polyester resin (A), preferably 10 An important feature is that after the injection molding is performed using a mold having a temperature of 40 ° C. to 40 ° C., heat treatment is performed outside the mold, thereby providing excellent impact resistance and separation while having excellent heat resistance. It becomes possible to provide an injection-molded product having moldability, and it is also possible to provide an injection-molded product excellent in biodegradability and flavor retention.

In the resin composition used in the present invention, the hard aliphatic polyester resin (A) and the aliphatic polyester resin (B) other than the hard aliphatic polyester resin (A) serve as a base resin. By allowing uniform dispersion of the soft polyester resin (C) and the inorganic filler, it is possible to impart a predetermined rubber-like elasticity that can impart impact resistance to the resin composition. Therefore, it is possible to remarkably improve moldability such as releasability.
That is, as is clear from the results of Examples described later, in Examples 1 to 4 using the resin composition, all have excellent release properties, no foaming during injection molding, impact resistance, 75 ° C. Filling heat resistance and container odor disappeared. On the other hand, if even one of the components (A) to (C) is missing, as shown in Comparative Examples 4 to 7, even if it is molded by the same manufacturing method as in Examples 1 to 4, the mold release failure or Further, thermal deformation occurs at the time of heat setting, or it becomes inferior in impact resistance, and only an injection molded product inferior to the injection molded container of the present invention can be obtained.

In the present invention, a mold having a temperature not higher than the glass transition temperature (Tg) of the hard aliphatic polyester resin (A) and preferably a mold having a temperature of 10 to 40 ° C. is used. After being injection-molded, it is possible to impart excellent moldability (mold release property) and heat resistance by being thermally fixed outside the mold.
That is, as is clear from the results of Examples described later, even when the resin composition is used, as shown in Comparative Examples 1 to 3, when 90 ° C. mold is used and heat setting is performed in the mold In order to make it possible to release the mold, a heat setting time of about 300 seconds is required. On the other hand, when the resin is exposed to a high temperature for a long time, the resin is thermally deteriorated, resulting in poor impact resistance. The odor cannot be lost.

In the present invention, after injection molding, by performing heat treatment outside the mold, it becomes possible to have both moldability and heat resistance, but by performing this heat treatment under wet heat conditions, The container odor derived from polylactic acid can be reduced, and it can be suitably used for a container containing, for example, a food product that requires a flavor property.
That is, as is clear from the results of the examples described later, in Examples 1 to 4 in which heat setting was performed outside the mold after injection molding under wet heat conditions, the odor of the container disappeared, whereas after injection molding In Example 5 in which heat setting was performed under dry heat conditions (90 ° C. oven) outside the mold, the same results were obtained for heat resistance, but the container odor did not disappear.

(A) Rigid aliphatic polyester resin The rigid aliphatic polyester resin used in the present invention is mainly composed of an aliphatic polyester mainly composed of lactic acid, and has the following formula (I)


(Chemical formula 1)
CH ₃ O
｜ ‖
-[-O-CH-C-]-(I)
It is mainly composed of repeating units represented by

The most preferred hard aliphatic polyester resin is composed of polylactic acid, and the structural unit is substantially composed of L-lactic acid, and the content of D-lactic acid as an optical isomer is 4.0% or less.
Of course, the polylactic acid used is not limited to this, but preferably has a weight average molecular weight (Mw) in the range of 10,000 to 300,000, particularly 20,000 to 250,000. The density is preferably in the range of 1.26 to 1.20 g / cm ³ , the melting point 160 to 200 ° C., and the melt flow rate (ASTM D1238, 190 ° C.) 2 to 20 g / 10 minutes.

Of course, the hard aliphatic polyester resin (A) used in the present invention is not limited to the above-mentioned polylactic acid, and other hard aliphatic polyester resins such as 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxy. Polyhydroxyalkanoates such as caproate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3-hydroxynanoate, 3-hydroxydecanoate, γ-butyrolactone, δ-valerolactone, ε-caprolactone, Polyglycolic acid or a copolymer thereof may be used.
The hard aliphatic polyester resin (A) preferably has a storage elastic modulus (E ′) at a temperature of 30 to 50 ° C. of 3.20 × 10 ⁹ Pa or more.

(B) Aliphatic polyester resin other than the hard aliphatic polyester resin The aliphatic polyester resin other than the hard aliphatic polyester resin used in the present invention is obtained by condensation polymerization of an aliphatic carboxylic acid and an aliphatic polyhydric alcohol. Since these aliphatic polyester resins are excellent in biodegradability and have appropriate flexibility, they can be used together with hard aliphatic polyester resins and soft polyester resins. The impact resistance can be improved without impairing the injection moldability.
Examples of the aliphatic carboxylic acid include oxalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, maleic acid, and linolenic acid. Aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, Examples include butylene glycol, hexane glycol, diethylene glycol, triethylene glycol, and neopentyl glycol.
Specific examples include polyethylene oxalate, polyethylene succinate, polybutylene succinate, polyethylene adipate, polyhexyl adipate, polypropylene adipate, polybutylene adipate, and the like. Particularly, in terms of biodegradability, polyethylene succinate Polybutylene succinate is preferably used.
The aliphatic polyester resin has a storage modulus at 30~50 ℃ (E ') is preferably in the 3.20 × ¹⁰ 9 Pa smaller range greater than 1.20 × ¹⁰ 9 Pa.

(C) Soft polyester resin The soft polyester resin used in the present invention is preferably a polyester elastomer containing an aromatic carboxylic acid component and an aliphatic carboxylic acid component as acid components. In this polyester-based elastomer, moderate crystallinity and moderate viscoelasticity are manifested by the presence of hard segments composed of aromatic carboxylic acid esters and soft segments composed of aliphatic carboxylic acid esters in the polymer chain. is doing.

Examples of the aromatic carboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, biphenyl-4,4′-dicarboxylic acid, diphenoxyethane-4,4′-dicarboxylic acid, P-β-oxyethoxybenzoic acid, 5 -Sodium sulfoisophthalic acid, trimellitic acid, pyromellitic acid, etc. can be mentioned.
On the other hand, examples of the aliphatic carboxylic acid component include aliphatic carboxylic acids having 4 or more carbon atoms, such as adipic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, hexahydroterephthalic acid, and cyclohexanediacetic acid.

  On the other hand, the alcohol component in the soft polyester includes ethylene glycol, 1,4-butanediol, propylene glycol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and bisphenol A. Examples include alcohol components such as ethylene oxide adducts, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitan.

Examples of suitable polyester-based elastomers are in no way limited to this, but include 2 to 70 mol% of aromatic carboxylic acid component, particularly 10 to 60 mol%, and 30 to 98 mol% of aliphatic carboxylic acid component, particularly 40 to 40 mol%. It is contained at a ratio of 90 mol%.
If the ratio of the aromatic carboxylic acid component in the polyester elastomer is below the above range, compatibility between the hard aliphatic polyester (A) and the aliphatic polyester (B) cannot be obtained, and as a result, impact resistance is reduced. Which is not preferred for the purposes of the present invention.
Moreover, since biodegradability will fall when the ratio of an aliphatic carboxylic acid component is less than the said range, it is not preferable when providing biodegradability to an injection molded product.

In a polyester elastomer, the aromatic ester unit and the aliphatic ester unit are generally present in the form of a so-called block copolymer chain, but of course, they may be present in the form of a random copolymer chain.
Examples of suitable copolymer compositions are polybutylene terephthalate / adipate, polyethylene terephthalate / adipate, polybutylene terephthalate / sebacate, polybutylene-2,6-naphthalate / adipate, polybutylene terephthalate / isophthalate / adipate, polybutylene terephthalate / isotope Phthalate / sebacate or a blend of two or more of these.

In general, aliphatic polyester has a problem that the melt property of the resin is inferior and melt molding is not always easy. To improve this problem, a high degree of chain elongation using a diisocyanate, an epoxy compound, or an acid anhydride is required. Although molecular weight enhancement (Japanese Patent Laid-Open No. 7-205278) has been proposed, such chain-extended polyester elastomer is also preferably used for the purpose of the present invention.
The soft aliphatic polyester resin used in the present invention preferably has a storage elastic modulus (E ′) at 30 to 50 ° C. of 1.20 × 10 ⁹ Pa or less.

(Resin composition)
In the present invention, (A) a hard aliphatic polyester resin, (B) an aliphatic polyester resin other than the hard aliphatic polyester resin, and (C) a soft polyester resin are blended to obtain a resin composition. Good to do.
The blend ratio of these resin components varies depending on the types of resin components and the required physical properties, and therefore cannot be specified unconditionally, but generally speaking, 35% by weight of (A) a hard aliphatic polyester resin is used. In particular, 40-60% by weight, (B) 5-60% by weight of aliphatic polyester resin, especially 10-50% by weight, (C) 1-30% by weight of soft polyester resin, especially 2-25% by weight It is good to mix | blend so that it may contain in the quantity.

  When the content of the hard aliphatic polyester resin (A) is less than the above value, the mechanical properties and other physical properties of the injection molded container are inferior to those in the above range. When the content of the soft polyester resin (C) is below the above range, the rubbery elasticity is insufficiently imparted and the impact resistance is inferior. On the other hand, when the content is above the above range, it is within the above range. The mold releasability from the injection mold becomes worse and the moldability becomes inferior.

In the present invention, the type and compounding ratio of the hard aliphatic polyester decomposable resin (A), the aliphatic polyester resin (B) other than the hard aliphatic polyester resin, the soft polyester resin (C) and the inorganic filler are changed. It is more preferable to adjust the final storage elastic modulus (E ′) of the resin composition to a desired range.
In the present invention, the final storage elastic modulus (E ′) at 30 to 50 ° C. of the resin composition is desirably in the range of 2.0 × 10 ^{8 to} 7.0 × 10 ⁹ Pa. It is possible to combine both impact resistance and mold release in injection molding.

  In the resin composition used in the present invention, in order to improve the melt physical properties of the resin composition, improve the melt moldability, and improve the shape stability during heat treatment, 1-40 per 100 parts by weight of the resin composition. Inorganic fillers in an amount of 2 parts by weight, in particular 2 to 30 parts by weight, can be included.

Examples of such inorganic fillers include talc, kaolin, clay, and kaolinite. Particularly, those containing 50% by weight or more of SiO ₂ can be preferably used. As the inorganic filler, those having an average particle diameter in the range of 0.1 to 50 μm can be preferably used.

  The resin composition of the present invention has various compounding agents known per se, for example, lubricants, plasticizers, leveling agents, surfactants, thickeners, thickeners, stabilizers, antioxidants, depending on the use. An agent, an ultraviolet absorber and the like can be blended according to a known formulation.

The resin composition used in the present invention was obtained by dry mixing the above-mentioned components with a conventionally known method such as a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, or the like, or by such a method. The mixture can be obtained by further melt-kneading with a single screw extruder, a twin screw extruder, a kneader, a Banbury mixer or the like.
As a method for uniformly dispersing the hard aliphatic polyester resin (A), the aliphatic polyester resin (B), the soft polyester resin (C) and the inorganic filler, a master containing a relatively high concentration of the soft polyester resin. A batch is prepared, and this master batch is mixed with the aliphatic polyester resin (A) and (B) and the inorganic filler.

(Injection molded container manufacturing method)
The injection-molded container of the present invention is formed by injection-molding a melt-kneaded product of the above resin composition. In the present invention, in particular, the molded product is taken out from the mold after injection molding and heat-treated outside the mold. This is very important.
In the present invention, since the heat treatment is performed outside the mold, the mold temperature in the injection molding is a mold having a temperature lower than the glass transition temperature (Tg) of the hard aliphatic polyester resin (A), preferably 10 to 40. The temperature is preferably in the range of ° C., and the holding time is preferably in the range of 2 to 100 seconds. Thereby, combined with the characteristics of the resin composition used, the releasability of the molded product can be remarkably improved.

As the injection machine, a known one having an injection plunger or a screw is used, and the resin composition is injected into an injection mold through a nozzle, a sprue and a gate. As a result, the resin composition flows into the injection mold cavity and is solidified into a container.
As the injection mold, either a one-gate or multi-gate injection mold may be used, and the injection temperature is preferably about 150 to 230 ° C. The shape of the container can be selected from shapes that can be injection molded, such as a cup shape and a square shape.

The molded product taken out from the injection mold is subjected to heat treatment outside the mold in order to improve heat resistance, and the temperature of such heat treatment may be in the range of 70 ° C. or more, particularly 75 ° C. to 105 ° C. Preferably, as described above, in order to remove the container odor derived from polylactic acid, it is preferable to perform the heat treatment particularly under wet heat conditions, particularly in an atmosphere of 30% RH or higher.
The heat treatment method under wet heat conditions is not limited to this. For example, the injection molded product is immersed in hot water maintained at the above temperature for 1 to 20 minutes, or 1 in a steam tunnel maintained at the above temperature. It can be heat-set under wet heat conditions by holding for 20 minutes or by holding in an autoclave maintained at the above temperature for 1 to 20 minutes.
In the present invention, when the container odor is not particularly problematic, such as containers other than food applications, the heat treatment can be performed under dry heat conditions. In this case, 1 to 20 in an oven in the above temperature range. What is necessary is just to heat-process for minutes.
In the present invention, before and after the heat treatment, the thermal shrinkage rate of the injection molded container is 5% or less, particularly 2% or less in terms of the axial shrinkage rate, and is excellent in heat resistance, particularly dimensional stability.

(Injection molded container)
The injection-molded container of the present invention is excellent in biodegradability, heat resistance, impact resistance, and flavor properties, so that it can be suitably used for packaging foods such as pudding, yogurt, confectionery, and dairy products. Can do.
Moreover, since it is excellent in heat resistance, it is suitable for, for example, high temperature filling at 70 ° C. or higher, and can be suitably used for chilled refrigeration after filling the contents at high temperature like pudding.

Next, the present invention will be described with specific examples.
(material)
Optically active isomer (d%) of polylactic acid and polybutylene succinate resin of d% = 2.0 and MFR = 6g / 10min (190 ° C / 216Kg), and 100 parts by weight composition of polybutylene terephthalate adipate resin A dry blend containing 28% by weight of talc having an average particle size of 16 μm was melt-mixed with a twin screw extruder and pelletized after strand forming.

(injection molding)
A cup-shaped mold having a diameter of 50 mmφ, a lower diameter of 40 mmφ, a depth of 50 mm, and an average wall thickness of 1.0 mm was used and injection molded into a cup-shaped container using an injection molding apparatus. When the mold temperature was 18 ° C., the molding cycle was 15 seconds for the cooling time (holding time). In injection molding to a heating mold having a mold temperature of 90 ° C., cooling (holding time) was set to 50 seconds, 100 seconds, and 300 seconds.

(Heat humidification treatment)
The cup immediately after molding was immersed in hot water at 90 ° C. for 10 minutes and cooled with cold water. Separately, the cup immediately after molding was stored in a 90 ° C. steam tunnel for 10 minutes and cooled with cold water. Similarly, the cup immediately after molding was treated with an autoclave at 90 ° C. under heating, pressurizing and humidifying conditions for 10 minutes and then cooled.

(Injection moldability)
When the mold release from the mold was good at the time of injection molding, the mold release was good, and when the molded product was not taken out of the mold and turned up or deformed, the mold release was poor. Similarly, when the injection molded resin is thermally deteriorated and the injection molded product is foamed, the resin is thermally deteriorated. When a molded product without foaming is obtained, the resin is not thermally deteriorated.

(Flavor test)
In-mold heat-fixed molding immediately after injection molding and a molding cup that has been heated and humidified (hot water, steam tunnel, autoclave) after injection molding are placed in an aluminum pouch, heat sealed, and 6 panelists in a sensory test clean room Thus, a sensory test for container odor was performed. A molded product having a strong container odor was rated as x, and a molded product that had no odor and could not be sensory was rated as ◯.

(Impact resistance)
After inversion with the mouth facing downward, a 30 g iron ball from 200 mm in height was dropped onto the bottom of the cup. A molded product having a cracked bottom in an iron ball drop test was evaluated as x for no impact resistance. Moreover, the molded product which does not break is rated as good with good impact resistance.

(Heat resistance test)
For molded products that had already undergone thermal deformation during 90 ° C hot water, steam tunneling, and autoclave treatment, they were not heat resistant and were marked as xx. In the above heat treatment, a molded product having no shape deformation of the container and having a heat shrinkage rate of 2% or less was defined as OO.
Next, a molded product that did not change in container shape and volume during 90 ° C. heat treatment was filled with 75 ° C. hot water and allowed to stand for 15 minutes. In this case, the molded product in which the initial cup shape was deformed (heat-shrinked) was regarded as having no heat resistance, and x. In addition, when filling with 75 ° C hot water and 2 minutes after filling with hot water, if the mouth is left after elliptical deformation with an ellipticity of 1.2 or more, the molded product whose shape has been restored is marked with ◯, and the cup without shape recovery is marked with △. .

Example 1
Optically active isomer (d%), polylactic acid and polybutylene succinate resin with dFR = 2.0 and MFR = 6g / 10min (190 ℃ / 2.16Kg), and aromatic biodegradable polyester (polybutylene terephthalate adipate) 28 parts by weight of talc having an average particle diameter of 16 μm was added to 100 parts of the resin composition having a composition of 40:40:20 by weight with a second feeder of a twin screw extruder, melt-mixed, and then subjected to strand molding and pelletizing. Next, this pellet was used for injection molding into a cup with an injection molding machine. The mold temperature was 18 ° C., and the cooling time (holding time) of the injection cycle was 15 seconds. Next, the molded product was immersed in a 90 ° C. constant temperature hot water layer for 10 minutes and heat fixed. Next, various evaluations of the obtained heat setting cup were performed. In the impact resistance test by the falling ball test, the bottom of the molded product was not cracked, the impact resistance was ensured, and the impact resistance was ○. Even in the 75 ° C. hot water filling test, the mouth portion was restored to its original shape even when the mouth portion was elliptically deformed 2 minutes after filling with hot water, and the 75 ° C. heat resistance was good. In the sensory test for container odor, all panelists judged that there was no odor in the odor determination, and the odor component was removed by immersion in hot water at 90 ° C., and the container odor sensory test was “good”. The evaluation results are shown in Table 1.

(Example 2)
Example 1 was repeated except that the weight ratio of the polylactic acid resin, polybutylene succinate resin, and polybutylene terephthalate adipate resin was 45:45:10. In the impact resistance test by the falling ball test, there was no bottom crack of the molded product, the impact resistance was ensured, and the impact resistance was ○. In the 75 ° C. hot water filling test, even when the mouth portion was elliptically deformed 2 minutes after filling with hot water, the mouth portion recovered to its original shape and the 75 ° C. heat resistance was ◯. In the sensory test for container odor, all the panelists judged that there was no odor, and it was confirmed that the odor component was removed by immersion in hot water at 90 ° C. The results are shown in Table 1.

(Examples 3 to 4)
The heat treatment of the injection-molded product was the same as Example 1 except that the heat treatment was 90 ° C. steam tunnel (Example 3) or 90 ° C. autoclave (Example 4). In the impact resistance test, there was no bottom crack of the molded product, the impact resistance was ensured, and the impact resistance was ○. In the 75 ° C. hot water filling test, there was no thermal deformation, and when the mouth was elliptically deformed 2 minutes after filling with hot water, the original shape was recovered and the 75 ° C. heat resistance was good. In the sensory test for container odor, all panelists judged that there was no odor component, and the odor component was removed by immersion in hot water at 90 ° C., and the sensory test for container odor was also good.

(Comparative Examples 1-3)
The mold heated to 90 ° C. was heat-set by injection molding held for different times. The same procedure as in Example 1 was repeated except that injection molding (90 ° C.-50 seconds hold: Comparative Example 1) (90 ° C.-100 seconds hold: Comparative Example 2) (90 ° C.-300 seconds hold: Comparative Example 3) was used. In this case, when the heat setting time is 50 seconds (Comparative Example 1) and the heat setting time is 100 seconds (Comparative Example 2), the heat setting of the molded product is insufficient, and the injection molded product cannot be released from the mold. The mold was defective. Further, even when the mold could be released from the mold, the molded product was deformed and practically a molded product could not be obtained. On the other hand, it was found that the molded product with a heat setting time of 300 seconds (Comparative Example 3) could ensure the mold release from the mold and the mold could be fixed by heat. When molding was repeated, the injection molded product foamed from around 10 shots. This foaming was judged to be due to thermal degradation of the resin staying in the barrel of the injection molding machine. In any case, in the heat fixing molding in the mold, the heat deterioration of the resin occurs when the heat fixing is ensured, and the heat fixing is insufficient in the state without the heat deterioration of the resin. In the impact resistance test of the molded product held at 90 ° C. for 300 seconds (Comparative Example 3), it was easily broken into pieces and the impact resistance was x. Further, in the odor sensory test of the molded odor, all the panelists judged that there was an odor on the nose, and the container odor test was x.

(Comparative Example 4)
The same procedure as in Example 1 was performed except that the injection resin composition was only polylactic acid resin. In this case, when immersed in hot water at 90 ° C. (heating and humidification treatment), the volume reduction rate of the molded product was 20% or more, resulting in thermal deformation and whitening along with shape deformation. Once the impact resistance test was performed, the bottom was easily cracked and the impact resistance was x.

(Comparative Example 5)
Example 1 was the same as Example 1 except that the resin composition was composed of polylactic acid not containing polybutylene terephthalate adipate resin and polybutylene succinate resin. In the sensory test for container odor, it was determined that all the panelists had no odor component, and it was confirmed that the odor component was removed by immersion in hot water at 90 ° C., and the container odor sensory test was ◯. Molded product after 90 ° C hot water immersion treatment is restored to its original shape even when the mouth is elliptically deformed 2 minutes after filling with hot water in the 75 ° C hot water filling test. Was ○. However, in the impact resistance test, the molded product cracked at the bottom and the impact resistance was x.
The evaluation results are shown in Table 1.

(Comparative Example 6)
The same as Example 1 except that the polylactic acid and polybutylene succinate resin and the polybutylene terephthalate adipate resin composition were 24:56:20 in weight ratio. First, it was found that the container shape had already been deformed by the 90 ° C hot water immersion treatment and could not be fixed by heat. As a result of conducting an impact resistance test, the molded product had no bottom crack and the impact resistance was good. Moreover, in the odor sensory test of container odor, all the panelists determined that it was not an odor component, the odor component was removed by immersing in 90 degreeC hot water, and the container odor sensory test was (circle). However, in the 75 ° C. hot water filling test, when the mouth portion was deformed 2 minutes after filling with hot water, the original shape was not recovered and the 75 ° C. heat resistance was x˜Δ. The evaluation results are shown in Table 1.

(Comparative Example 7)
The same procedure as in Example 1 was conducted except that the weight ratio of the resin composition comprising polylactic acid and polybutylene succinate resin and polybutylene terephthalate adipate resin was 50: 0: 50. In this case, some of the injection-molded products were defective from the mold, and the injection moldability was poor. Further, it was found that when the molded product that could be released from the mold was immersed in hot water at 90 ° C., the container shape was easily deformed and could not be fixed by heat. Therefore, as a result of the impact resistance test, there was no bottom crack in the molded product and the impact resistance was ○. However, as shown above, it was thermally deformed by injection molding and 90 ° C hot water treatment, so it was practical. No sex.

(Example 5)
The same procedure as in Example 1 was performed except that the heat treatment of the injection molded product was a dry heat treatment in a 90 ° C. oven. In the impact resistance test, there was no bottom crack of the molded product, the impact resistance was ensured, and the impact resistance was ○. In the 75 ° C. hot water filling test, there was no thermal deformation, and when the mouth was elliptically deformed 2 minutes after filling with hot water, the original shape was recovered and the 75 ° C. heat resistance was good. In the sensory test for container odor, all panelists judged that there was an odor on the nose, and the container odor test was x.

Claims (12)

A hard aliphatic polyester resin (A), an aliphatic polyester resin (B) other than the hard polyester resin (A), a polyester elastomer containing an aromatic carboxylic acid component and an aliphatic carboxylic acid component as acid components ( Ri from C) formed, said hard aliphatic polyester resin (a) and 35 wt% or more, the aliphatic polyester resin (B) 5 to 60 wt%, the amount of polyester-based elastomer (C) 1 to 30 wt% the resin composition you containing in, after injection molding using a glass transition temperature (Tg) of the mold below the temperature of the hard aliphatic polyester resin (a), the characterized in that a heat treatment outside the mold Manufacturing method of injection molding containers for high temperature filling . Temperature of the mold is manufactured method 請 Motomeko 1, wherein the glass transition temperature (Tg) of the temperature of below the temperature at 10 to 40 ° C. hard aliphatic polyester resin (A). The manufacturing method of Claim 1 or 2 in which the said resin composition further contains an inorganic filler in the ratio of 1-40 weight part per 100 weight part of resin compositions. Wherein the inorganic filler is A process according to any one of claims 1 to 3 as an inorganic filler containing SiO ₂ more than 50 wt%. The process according to any one of claims 1 to 4 , wherein the polyester elastomer (C) is polybutylene terephthalate adipate or polyethylene terephthalate adipate. The method according to any one of claims 1 to 5 , wherein the hard aliphatic polyester resin (A) is a resin mainly composed of polylactic acid. The process according to any one of claims 1 to 6 , wherein the aliphatic polyester resin (B) is polybutylene succinate or polyethylene succinate. The process according to any one of claims 1 to 7 , wherein the thermal shrinkage rate of the injection-molded container before and after the heat treatment is 5% or less. The method according to any one of claims 1 to 8 , wherein the heat treatment is performed under wet heat conditions. The method according to any one of claims 1 to 9 , wherein the heat treatment is any one of heat treatment by hot water at 70 ° C or higher, a steam tunnel at 70 ° C or higher, or an autoclave at 70 ° C or higher. The heat treatment A process according to any one of claims 1 to 8 is due to dry heat treatment above 70 ° C.. An injection-molded container for high-temperature filling molded by the production method according to any one of claims 1 to 11 .