JP2001018290A - Aliphatic polyester stretch-molded object and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a biaxially stretched molded object made of aliphatic polyester eliminated or reduced in the anisotropy of mechanical strength characteristics and enhanced in gas barrier properties. SOLUTION: In a method for producing an aliphatic polyester stretch-molded object by the biaxial stretch molding of a preform of a resin based on aliphatic polyester, a negative gradient is provided to a stretching speed in the biaxial stretching of the preform so that an initial stretching speed becomes high and a final stretching speed becomes low. By vapor-depositing hard carbon film, gas barrier properties are also enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch molded article of an aliphatic polyester having improved mechanical strength anisotropy and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the amount of solid waste discharged from cities has become enormous, and is approaching the limit of waste disposal capacity. Plastic has always been pointed out as one of the causes of this solid waste.

As an ideal solution for plastic waste, degradable plastics that disappear in the natural environment are attracting attention. Degradable plastics include photodegradable plastics, in which the molecular chains of the polymer are cut by ultraviolet light, and biodegradable plastics, which are broken down by the action of enzymes released by bacteria and fungi outside the body.

[0004] However, in the case of photodegradable plastics, there is no expectation of an effect by burial treatment in the soil, and there is a risk of environmental pollution due to decomposition products.

[0005] As biodegradable plastics, conventionally, aliphatic polyesters such as polyhydroxybutyrate (PHA), 3-hydroxybutyrate (3HB) and
-Random copolymer with hydroxyvalerate (3HV), poly (ε-caprolactone) (PCL), polybutylene succinate (PBS), polybutylene succinate adipate (PBAS), polylactic acid (PLLA)
Etc. are known.

[0006]

However, although these aliphatic polyesters are excellent in harmony with the environment such as biodegradability, they still have problems to be solved in moldability. are doing. As an example, aliphatic polyesters have a problem that the melt properties of the resin are inferior and that molding such as direct blow, injection stretch molding, and thermoforming of sheets is difficult. For this reason, it has been proposed to improve the melt tension by adding an inorganic filler (Japanese Patent Laid-Open No. 5-289623) and to increase the molecular weight by extending the chain length using a diisocyanate, a diepoxy compound or an acid anhydride (Japanese Patent Laid-Open No. 7-205278). . In addition, the aliphatic polyester can generally improve the material strength by processing by stretch molding.

[0007]

In the case of aliphatic polyester, mechanical strength such as yield point strength and elastic modulus is improved by stretching, like ordinary plastics. However, when the aliphatic polyester is biaxially stretch-formed, the obtained stretch-formed product has anisotropy in mechanical strength.

For example, in a biaxially stretched molded article of aromatic polyester and polyethylene terephthalate (PET), the stretching direction, ie, the machine direction (MD) and the transverse direction (T
Although the yield point strength of D) and the yield point strength in the direction of 45 degrees from MD and TD show almost the same strength, the aliphatic polyester such as polylactic acid is stretched in the stretching direction, that is, the machine direction (M
D) and the yield strength in the transverse direction (TD) are MD and T
It is lower than the yield point strength in the direction of 45 degrees from the D direction.

As described above, the biaxially stretched molded article of the aliphatic polyester has anisotropy in mechanical strength, and the strength is particularly low in the stretching axis direction where the strength should be increased. Is difficult. For example, in a three-dimensional molded container such as a bottle or a cup, it is suitable to set the stretching direction to the container axial direction and the container circumferential direction. In this case, having the mechanical strength of the surface formed by the stretching axis isotropic is also an important point for preventing buckling, preventing cracking due to a drop impact, and preventing cracking due to expansion, contraction and deformation. However, the mechanical strength is different even in the direction in which the strength in the axial direction and the circumferential direction forms a 45-degree direction with respect to the stretching axis, so that the strength of the biaxially stretched molded article of the aliphatic polyester has not achieved the intended purpose. On the other hand, it is not practical to perform the stretching operation in a direction deviated by 45 degrees from the axial direction or the circumferential direction of the container.

In addition, it was found that the biaxially stretched molded article having anisotropy in mechanical strength as described above often had a tendency to crack during compression deformation as shown in Comparative Examples.

Accordingly, an object of the present invention is to provide a biaxially stretched molded article formed of an aliphatic polyester, wherein the anisotropy of the mechanical strength described above is eliminated or reduced, and the aliphatic polyester has a stable mechanical strength characteristic. An object of the present invention is to provide an axially stretched molded article and a method for producing the same.

[0012]

According to the present invention, there is provided a method for producing a stretched aliphatic polyester article comprising biaxially stretching a preform of a resin mainly composed of an aliphatic polyester. There is provided a method for producing a stretched article characterized by stretch molding in which a biaxial stretching is performed with a negative gradient in the stretching speed such that the initial stretching speed is increased and the final stretching speed is decreased. According to the present invention, there is provided a stretched molded article formed from a resin mainly composed of an aliphatic polyester, the following equation (1) T in ₄₅ ≦ Tx ‥ (1) formula, Tx biaxial stretching of the molded body , And T ₄₅ is a tensile yield point strength (MPa) in a direction of 45 ° with respect to the stretching direction of the molded body, and has a strength characteristic expressed by: An aliphatic polyester stretch molded article is provided. The aliphatic polyester stretched molded product according to the present invention has the following formula (2) Do = (S-Sa) / S ‥ (2) where S is a chemical shift of 100 when a molded product sample is measured by ¹³ C wide-area NMR. Represents a peak area of about 300 ppm, and Sa represents a peak area of an NMR spectrum when the amorphous powder of the sample is measured in the same manner as described above. The degree of orientational crystallinity (Do) is 0.15 or more. It is preferred that Further, the aliphatic polyester used in the present invention is an aliphatic polyester having a glass transition point (Tg) of -60 ° C or higher, and represents polyhydroxyalkanoate. According to the present invention, there is further provided a packaging container comprising the above stretch-formed body. In the stretch molded article according to the present invention, a hard carbon film can be formed by a chemical vapor deposition method for the purpose of suppressing gas permeability through the vessel wall and preventing sorption of flavor components in the contents.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Action] In the present invention, the biaxial stretching of an aliphatic polyester preform is carried out by stretching at a high initial stretching speed and at a low final stretching speed with a negative gradient. Thus, the present invention is based on a new finding that the anisotropy of strength of a stretch molded article can be eliminated or reduced.

That is, in the present invention, by performing a biaxial stretching operation in which the initial stretching speed is increased and the final stretching speed is decreased, and the stretching speed is provided with a negative gradient, mechanical stretching of the aliphatic polyester stretch molded article is performed. This is important for eliminating or reducing strength anisotropy. For example, when the stretching speed is constant, when the stretching speed is high or when the stretching speed is low, the yield point strength in the stretching direction is 4
It is lower than the yield point strength in the 5 degree direction (diagonal direction). On the other hand, the yield strength in the stretching direction is reduced by the yield strength in the diagonal direction by increasing the initial stretching speed and performing stretching with a negative gradient in the stretching speed to decrease the final stretching speed. Can be equal to or greater than. As a result, the disadvantage that the strength in the stretching direction is reduced can be eliminated.

[0015] The stretched aliphatic polyester molded article according to the present invention exhibits strength characteristics satisfying the above formula (1). For this reason, the container made of the stretched molded article of the present invention has excellent buckling resistance and drop impact resistance, and has the advantage that cracking due to expansion, shrinkage, and deformation is effectively prevented.

The stretch molded article according to the present invention has the formula (2)
It is preferable that the oriented crystallinity (Do) defined by the formula (1) is 0.15 or more, particularly 0.2 or more, from the viewpoint of mechanical properties, transparency and heat resistance.

In general, the degree of crystallinity of a thermoplastic polyester derived from a dibasic acid mainly composed of an aromatic carboxylic acid and glycol can be measured by a density method. The relationship with the degree of conversion is represented by the following equation (3). Crystallinity X _c = (ρ _c / ρ) × {(ρ−ρ _am ) / (ρ _c −ρ _am )} × 100 (3) where ρ is an n-heptane-carbon tetrachloride density gradient Density of sample measured at 20 ° C in a tube (manufactured by Ikeda Rika), ρ
_am is the amorphous density (1.335 g / cm ³ ), and p _c is the crystal density (1.455 g / cm ³ ).

However, in the case of aliphatic polyester, the density of amorphous and highly oriented samples of polylactic acid and the like is almost constant, and the oriented crystallinity cannot be determined by the density method.

The present inventor has proposed that an aliphatic polyester is made of ¹³ C
Chemical shift 100 to 30 as measured by broad NMR
It has been found that the peak area at 0 ppm (carbonyl carbon region) is closely related to the degree of orientation of the aliphatic polyester, and the degree of orientation can be measured from this peak area. That is, for the aliphatic polyester stretched molded body, the area S of the NMR spectrum was obtained, and then the peak area Sa of the NMR spectrum when the amorphous powder of this sample was measured in the same manner as above was obtained. The orientation crystallinity (Do) is calculated. There is a one-to-one correspondence between the orientational crystallinity (Do) and the stretching ratio thus obtained.

FIG. 1 shows the relationship between the draw ratio (axial draw ratio, area draw ratio) and the obtained oriented crystallinity (Do) for various stretched molded products of aliphatic polyester. According to FIG. 1, it can be seen that as the stretching ratio increases, the degree of oriented crystallinity increases.

According to the present invention, as described above, the aliphatic polyester is subjected to a biaxial stretching operation in which the initial stretching speed is increased and the final stretching speed is decreased, and a stretching gradient is provided with a negative gradient. When the strength characteristics of the stretched molded product satisfy the above-mentioned formula (1), mechanical strength anisotropy is eliminated or reduced, and the improvement of the anisotropy is due to the orientation crystallinity (Do) of 0.15. It should be noted that this is achieved in the above areas.

(Aliphatic polyester resin) In the present invention, as the aliphatic polyester resin, any biodegradable aliphatic polyester resin mainly composed of hydroxyalkanoate units is used. The aliphatic polyester resin should have at least a molecular weight capable of forming a film, and generally has a number average molecular weight of 100
00 to 300,000, especially 20,000 to 20,000
It should be in the range of 0. Examples of suitable aliphatic polyester resins are polyhydroxyalkanoates or copolymers thereof.

As the polyhydroxyalkanoate,
The following formula

Embedded image In the formula, R is a hydrogen atom or a linear or branched alkyl group, and n is a positive integer including zero, for example, lactic acid [R = CH ₃ , n = 0 , LLA], 3- hydroxybutyrate _{[R = CH 3, n =} 1,3HB], 3- hydroxyvalerate _{[R = CH 2 CH 3,} n = 1,3HV], 3- hydroxy-caproate [R _{= (CH 2) 2 CH 3} , n = 1,3HC], 3- hydroxy-heptanoate _{[R = (CH 2) 3} CH 3, n = 1,3H H], 3- hydroxyoctanoate [R = (CH ₂ ) ₄ CH ₃ n = 1, 3HO], 3-hydroxynonanoate [R = (CH ₂ ) ₅ CH ₃ , n = 1, 3HN], 3-hydroxydecanoate [R = (CH ₂ )] _{6 CH 3, n = 1,3HD]} , γ- Bed One or two types of lolactone [R = H, n = 2, BL], δ-valerolactone [R = H, n = 3, VL], ε-caprolactone [R = H, n = 4, CL] Polymers composed of the above are exemplified.

The polyhydroxyalkanoate includes polylactic acid (polylactic acid includes poly (L-lactic acid) having a structural unit of only L-lactic acid, poly (D-lactic acid) including only D-lactic acid, and L-lactic acid. Units and poly (DL-lactic acid) present in an arbitrary ratio of D-lactic acid species.)
It may be a homopolymer such as caprolactone or a copolymer with another hydroxyalkaliate. Further, a copolymer obtained by copolymerizing 3-hydroxybutyrate and another 3-hydroxyalkanoate, particularly 3-hydroxyvalerate, may be used.

The aliphatic polyester used in the present invention preferably has a glass transition point (Tg) of -60 ° C or more, particularly preferably 30 ° C or more. Among these aliphatic polyesters, polylactic acid is mentioned as an aliphatic polyester which is industrially mass-produced, easily available, and environmentally friendly. Polylactic acid (PLLA) is a resin using cereal starch such as corn as a raw material, and is a lactic acid fermentation product of starch and a polymer using L-lactic acid as a monomer. In general, it is produced by a ring-opening polymerization method of lactide, which is a dimer, and a direct polycondensation method. This polymer is decomposed by water and carbon dioxide gas by microorganisms existing in nature, and is attracting attention as a complete recycling system type resin. The glass transition point (Tg) is also about 58 ° C., which is close to that of PET.

The stretch molded article of the present invention can use the above-mentioned aliphatic polyester, especially polylactic acid alone, or can be a blend with another aliphatic polyester or another resin or a laminate with another resin. Can also be used.

Further, other resins usable in the form of a blend or a laminate with the above aliphatic polyester include:
Barrier resins, for example, a hydroxyl group-containing thermoplastic resin having a barrier property to oxygen, a nylon resin, a barrier polyester resin, a hynitrile resin, and a cyclic olefin copolymer having a barrier property to water vapor may be mentioned. it can. Among these, a hydroxyl group-containing resin is preferable in terms of biodegradability, and any resin can be used as long as thermoforming is possible. This resin has, in its molecular chain, a repeating unit having a hydroxyl group and a unit for imparting thermoformability to the resin. The hydroxyl group-containing repeating unit may be a vinyl alcohol unit or a hydroxyalkyl (meth) acrylate unit, but a vinyl alcohol unit is preferred from the viewpoint of biodegradability. Other units contained in the hydroxyl group-containing resin include olefin units such as ethylene and propylene, vinyl ester units such as vinyl acetate, and alkyl (meth) acrylate units. These hydroxyl-containing resins should have at least a molecular weight sufficient to form a film.

A preferred hydroxyl group-containing resin comprises a copolymer containing 10 to 40 mol% of ethylene units, 40 to 88 mol% of vinyl alcohol units, and 50 mol% or less of ester-containing vinyl units. By using such a hydroxyl group-containing polymer as a blend or a laminate, it is possible to improve the gas barrier properties of the stretched molded article, and to achieve the advantage that the biodegradability is not substantially inhibited.

The stretch molded article of the present invention may contain various coloring agents, fillers, inorganic or organic reinforcing agents, lubricants, plasticizers, leveling agents, surfactants, thickeners, etc. A viscosity reducing agent, a stabilizer, an antioxidant, an ultraviolet absorber, a rust inhibitor and the like can be blended according to a known formulation.

(Stretched Molded Article and Method for Producing the Same) The stretched molded article of the present invention is obtained by stretching a preformed article of a resin mainly composed of an aliphatic polyester by increasing the initial stretching rate and decreasing the final stretching rate. It is manufactured by performing biaxial stretching in which a negative gradient is provided.

The preform can be produced by a known extrusion molding method, injection molding method or compression molding method. For example, by extruding the molten resin through a T-die, a thin sheet of a stretched film, and a sheet for a film or a cup for air pressure molding or plug assist molding are formed. By extruding the molten resin through a ring die, a pipe-shaped preform for molding a container can also be formed.
Further, a preform for a three-dimensional container such as a bottle is formed by injecting the molten resin into a mold including a cavity mold and a core mold by using a screw or a plunger. A three-dimensional preform such as a bottle can also be obtained by compressing a molten resin parison with a cavity mold and a core mold.

In order to produce a preform made of a laminate of an aliphatic polyester and another resin, for example, a hydroxyl group-containing resin, a lamination technique known per se is used. Is produced by co-extrusion using a multilayer die using an extruder corresponding to the above-mentioned method. In injection molding, a multilayer preform can be formed by a co-injection method or a sequential co-injection method known per se. Furthermore, even in the compression molding method, by forming a multilayer molten resin parison by co-extrusion etc.,
Multilayer preforms can be manufactured.

The stretching of the preform is performed at the stretching temperature of the aliphatic polyester by the above-mentioned method at the stretching speed, and the oriented crystallinity (Do) of the obtained molded article is 0.1 mm.
This is performed under the condition of 15 or more.

Although the stretching temperature varies depending on the type of the aliphatic polyester, generally, the stretching temperature is from Tg to Tg based on the glass transition point (Tg) of the aliphatic polyester.
A temperature of + 60 ° C. is appropriate, for example for polylactic acid
A temperature of Tg + 10 ° C. to Tg + 20 ° C. is appropriate.

[0035] In the present invention, performs the initial biaxial stretching in which a negative slope stretching speed large and the stretching speed was reduced drawing speed of the end of the stretching speed of the first stage and (V ₁₎ Final The ratio (V ₁ / V ₂ ) of the stretching speed (V ₂ ) of the step is generally preferably in the range of 3 to 70 in order to eliminate or reduce the anisotropy of strength. That is, when the ratio of V ₁ / V ₂ is lower than the above range, it tends to be difficult to improve the strength characteristics so as to satisfy the above formula (1).
If this ratio exceeds the above range, the productivity of stretch molding is undesirably deteriorated.

The stretching speed in the first stage is not particularly limited, but is generally preferably in the range of 1 m / sec to 50 m / sec. The change of the stretching speed can be changed stepwise over two or more stages or continuously. Of course,
In any of these cases, a gradient must be provided in the stretching speed such that the stretching speed monotonically decreases from the initial stage to the final stage. The switching of the stretching speed can be performed by changing the moving speed of the stretching rod or the gripping chuck in mechanical stretching, or by changing the blow pressure in expansion stretching.

The stretching ratio is such that the degree of orientational crystallinity (Do) defined by the above formula (2) is 0.15 or more. The stretching ratio is 1.4 to 4 times, the stretching ratio in the transverse direction (container circumferential direction) is 1.4 to 4 times, and preferably the area stretching ratio is 2 to 16 times.

In the stretch molding of the present invention, the reason why the anisotropy of strength is eliminated or reduced by providing a negative gradient in the stretching speed has not yet been elucidated. However, under such stretching conditions, the possibility that relaxation of strain due to stretching and a kind of heat fixation have occurred cannot be denied.

The aliphatic polyester stretched molded article according to the present invention is free from anisotropy in mechanical strength and is excellent in various properties as a container, but has a gas barrier property as compared with aromatic polyester. Tend to be slightly inferior.
In order to improve this, it is preferable to form a hard carbon film on at least one surface of the stretched molded body by a chemical vapor deposition method (CVD).

A hard carbon film is generally referred to as DLC (diam).
ond like carbon) film, i carbon film or hydrogenated amorphous carbon film (a-C: is of the called H), consist Amorufuasu carbon film was mainly SP ³ bond. This carbon film is excellent in the effect of suppressing sorption of low molecular organic compounds such as flavor components and gas barrier properties. The thickness of the carbon film is preferably in the range of 0.05 to 5 μm from the viewpoint of improving these properties and the adhesion to plastic, durability, transparency, and the like.

The hard carbon film can be formed by a known chemical vapor deposition method (CVD), in particular, plasma CVD. Plasma CVD is to grow a thin film using gas plasma. Basically, a gas containing a raw material gas is discharged under a reduced pressure with electric energy by a high electric field to decompose and generate a substance to be generated. It consists of a process of depositing on a substrate through a chemical reaction in the gas phase or on the substrate. The plasma state is realized by glow discharge, and by this glow discharge method,
A method using a DC glow discharge, a method using a high-frequency glow discharge, a method using a microwave discharge, and the like are known.

Since plasma CVD utilizes the direct decomposition of gas molecules by high-speed electrons, it is in a thermal non-equilibrium state in which the electron temperature and the gas molecule temperature are different so that a source gas having a large generation energy can be easily dissociated. It has the advantage that a low-temperature process is possible and that a relatively uniform amorphous film can be formed even when the substrate temperature is low, and it can be easily applied to an aliphatic polyester stretch molded article.

As the raw material gas for forming the film, aliphatic or aromatic hydrocarbons, aromatic hydrocarbons, oxygen-containing hydrocarbons, nitrogen-containing hydrocarbons, etc., which are gaseous or liquid at ordinary temperature, are used.
Among them, benzene having 6 or more carbon atoms, toluene, o
-Xylene, m-xylene, p-xylene, cyclohexane and the like are desirable. These raw materials may be used alone or may be used as a mixture of two or more gases.
Further, these gases may be diluted with a rare gas such as argon or helium before use.

To form a hard carbon film, a stretched aliphatic polyester article is filled in a reaction vessel, and the pressure in the reaction vessel is reduced. The degree of vacuum at this time is generally 10 ⁻² to 10
A range of ^-5 torr is desirable. Next, the source gas is supplied into the reaction vessel, glow discharge is started, and a film is formed. The pressure in the reaction vessel is 0.5-0.001 torr
It is preferably in the range of r. In order to further improve the adhesion between the carbon film and the molded body, the surface of the molded body can be activated by performing a plasma treatment with an inorganic gas such as argon or oxygen before forming the carbon film.

(Usage) The stretch molded article of the present invention can be used in various plastic packaging containers such as bottles, cups, tubes,
They are useful as plastic cans, pouches, caps, etc., as packaging materials for films, trays, etc., as distribution containers such as containers, tanks, baskets, etc., and as structures such as pipes and cases.

[0046]

Next, the present invention will be described with reference to specific examples. The present invention is not limited to the following embodiments.

(Molding) Bottle molding: polylactic acid having a weight average molecular weight of 180,000
Was used. 190-200 ° C using an injection molding machine
Below, a preform having a diameter of 28 mmφ was injection molded. Money
Mold temperature 15 ° C. Next, convert the preform to an infrared heater
After reheating to 65 to 75 ° C, using a mold blow molding machine,
A round 500 ml mold blow bottle was prepared. this
In the case, the blow pressure is 30 kg / cm compressed air pressure.²Suppose
Pressure blow molding was performed. Also, compressed air blowing port and exhaust port
And the initial compressed air pressure is 30 kg / cm ²age
After opening the exhaust valve for a while,
And reduce the final blow pressure to 0.5kg
/ Cm²The mold was blown to a reduced pressure.

Cup molding: The above-mentioned polylactic acid was used. Using an extruder, C1 to C4 of the screw part were 190 to 200
00 ° C, T-die temperature 190 ° C, 400mm width, 2
A sheet having a thickness of mm was prepared. The sheet was reheated to 70 ° C. using a thermoform molding machine, and then stretched in the longitudinal direction by conical plug assist, and at the same time, a cylindrical cup was formed with compressed air. (80mmφ diameter, 50mmφ bottom diameter,
Height 90 mm). Mold temperature 15 ° C. In this case, the pressure of the blown compressed air was set to a constant pressure of 10 kg / cm ^{2 and} the pressure of the blown compressed air was increased to an initial air pressure of 10 kg / c.
Molding was carried out with varying from m ² to 0.5 kg / cm ^2.

Stretched sheet molding: The above-mentioned polylactic acid was used.
Using an injection molding machine, an 11 mm × 11 mm size flat plate having a thickness of 2 mm was injection molded under a condition of 190 to 200 ° C. Mold temperature 15 ° C. Next, the injection molded flat plate was reheated to 70 ° C. using a biaxial stretching device, and then stretched 2 × at a stretching speed of 10 m / min.
Simultaneous biaxial stretching was performed twice, 2.5 × 2.5 times, and 3 × 3 times. Further, the stretching ratio is kept constant at 3 × 3 times, and the stretching speed is 5 × 3.
0mm / min, 500mm / min, 1000mm /
Simultaneous biaxial stretching was performed with the min. Similarly, the stretching ratio is set to 3 × 3 times, and the initial stretching speed is 1000 mm /
min and within 500 mm stepwise within the biaxial stretching time.
The biaxial stretching was performed at a reduced stretching speed of 50 mm / min.

(Evaluation) Stretching stress of biaxially stretched sheet: The stretching stress at the time of biaxial stretching was measured using a biaxial stretching apparatus manufactured by Toyo Seiki Co., Ltd. In this case, the stretching axes were biaxial, and the stretching stress of each stretching axis showed the same pattern. For this reason, it showed uniaxial stretching stress. Mechanical strength: A biaxially stretched sheet was used. The AS has a direction in which the axis is the stretching axis direction (X, Y) and a direction in which the axis is the diagonal direction (45 ° direction) formed by the stretching biaxial directions.
Cut out TMD-1822 type dumbbell, and ORIENT
A tensile stress-strain curve was obtained using a tensile tester manufactured by EC. Compressive strength: A mold blow bottle and a thermoform molding cup were used. Using a jig of 10 mmφ on the body (horizontal direction) of the bottle and the cup, a compression strain test of a strain amount of 10% was performed. Bottles and cups that generated cracks in the body direction during strain deformation were marked with “x”, and bottles and cups that did not crack with deformation were marked with “○”.

¹³ C wide-area NMR measurement: manufactured by JEOL
Using an NMR apparatus, using a biaxially stretched sheet, a mold blow bottle, and a piece cut out from the Thermofoam cup in a direction of 4 mm in width, superposed in the cutout direction, and then filled in a Diflon holder. .
Then, ¹³ C wide-area NMR measurement was performed. Further, the focused nucleus was limited to the carbonyl carbon region. The obtained NMR spectrum shows the amorphous pattern shown in FIG. 1 if only the non-oriented component is present. If an orientation component is present, an angle-dependent spectrum pattern between the orientation axis of the orientation component and the direction of the static magnetic field of NMR as shown in FIGS. 3 and 4 is shown in addition to the amorphous pattern shown in FIG. 2 ( For example, FIG. 3 → vertical, FIG. 4 → parallel). Therefore, by subtracting the powder pattern shown in FIG. 2 from the actually measured ¹³ C wide NMR measurement spectrum,
The composition fraction of the oriented crystal component can be determined. First, create a thin amorphous samples quenched molten sample, after chopped, randomly packed in Daifuron made sample tube, ¹³ C
Broad NMR measurement was performed (FIG. 1). Next, a biaxially stretched sheet,
The sections cut out from the mold blow bottle and the thermofoam cup were overlapped with each other in the same cutting direction, and ¹³ C wide-area NMR measurement was performed. After reading each measured spectrum with an image scanner, the X and Y coordinates of the spectrum were obtained. Then, using a spreadsheet software (Microsoft, Excel (registered trademark)), the powder pattern of the non-oriented component was determined from the ¹³ C wide NMR spectrum of the biaxially stretched sheet, the mold blow bottle, and the section of the thermoform cup. deducted. The spectral peak intensity before calculation was set to S. The amorphous component subtracted by the calculation was defined as Sa. In this case, S-Sa = Sc is the oriented crystal component. Therefore, here, Do = (S
-Sa) / S indicates the composition of the oriented crystal component. The ¹³ C wide NMR measurement shown here is a general analytical technique.

Example 1 A flat plate having a thickness of 2 mm was reheated to 70 ° C.
After heating, use a biaxial stretching device to simultaneously stretch 3 × 3
Stretching was performed. The initial stretching speed is 1000 mm / min
During the simultaneous biaxial stretching time, the stretching speed is gradually increased to 500
mm / min and 50 mm / min. Same as above
For the biaxially stretched sample, the stretching axis direction and its diagonal direction (4
5 °) mechanical strength (yield point strength), biaxial of the same sample
Stretching stress pattern during stretching, and ¹³C-wide NMR
Table 1 shows the degree of orientational crystallinity determined from the measurement.

[Comparative Example 1] A flat plate having a thickness of 2 mm was reheated to 70 ° C.
After heating, use a biaxial stretching device to adjust the stretching ratio to 3 × 3 at the same time.
Axial stretching was performed. Stretching speed is 1000 mm / min, 5
Each speed of 00mm / min, 50mm / min
At a constant speed. For the above simultaneous biaxially stretched sample,
Mechanical strength in the extension axis direction and its diagonal direction (45 ° direction)
(Yield point strength), stretching stress pattern during biaxial stretching of the same sample
And ¹³Oriented crystallinity determined from wide C NMR
Are shown in Table 1.

[Comparative Example 2] A flat plate having a thickness of 2 mm was reheated to 70 ° C.
After heating, simultaneous biaxial stretching was performed using a biaxial stretching apparatus. Delay
The elongation speed is 10 m / min and the elongation ratio is 2 ×
It was changed to 2 times, 2.5 × 2.5 times, and 3 × 3 times. the above
For simultaneous biaxially stretched samples, stretch axis direction and its diagonal direction
(45 ° direction) mechanical strength (yield point strength)
Stretching stress pattern during biaxial stretching, and ¹³Wide CN
Table 2 shows the degree of orientational crystallinity determined from MR.

Example 2 The above-mentioned polylactic acid was used. Using an extruder, C1 to C4 of the screw part were 190 to 200
400 ° C, 00 ° C, T-die temperature 190 ° C,
A sheet having a thickness of 2 mm was prepared. The sheet was reheated to 70 ° C. using a thermoform molding machine, and then stretched in the longitudinal direction with a conical plug assist, while simultaneously reducing the initial compressed air pressure from 15 kg / cm ² to 1 kg / cm ² low pressure air at the end, and forming a cylindrical cup. Was molded. (Diameter 80mmφ, bottom diameter 5
0mmφ, height 90mm) Mold temperature 15 ° C. A 10 mmφ flat jig is used for the cup body (lateral direction),
% Compression deformation. Cups that did not crack in the trunk during compression strain deformation were marked with ○, and cups that cracked in the trunk during deformation were marked X. The results are shown in Table 3.

Comparative Example 3 The above-mentioned polylactic acid was used. Using an extruder, adjust the screw temperature and C1 to C4 to 190
~ 200 ° C, T-die temperature at 190 ° C, 400mm
A sheet having a width of 2 mm was prepared. This sheet was heated to 70 ° C. using a thermoform forming machine, then stretched in the longitudinal direction by conical plug assist, and simultaneously formed into a cylindrical cup with compressed air. (Diameter 80mmφ, Bottom diameter 50mm
φ, height 90mm) Mold temperature 15 ° C. In this case, the pressure of the blown compressed air was 15 kg / cm ² . Using a 10 mmφ flat plate jig in the cup body (lateral direction), compression strain deformation was performed with a strain amount of 10%. A cup that did not crack in the trunk after strain deformation was marked with ○, and a cup that cracked in the trunk during deformation was marked X. The results are shown in Table 3.

Example 3 The polylactic acid was used. Using an injection molding machine, a preform of 28 mmφ was injection-molded under a condition of 190 to 200 ° C. Mold temperature 15 ° C. After the preform was reheated to 70 to 75 ° C. using an infrared heater, a round 500 ml-capacity blow bottle was prepared using a mold blow molding machine. The blow pressure at the time of blow is set to 30 at the beginning with the compressed air blow-in port and the exhaust port.
After adjusting the pressure to Kg / cm ² , the exhaust valve was temporarily opened, and the blow pressure was reduced stepwise within the blow time. Finally 0.
The pressure was reduced to 5 kg / cm ² and the mold was blown. Using a 10 mmφ flat jig, the body (horizontal direction) of the molding die blow bottle was subjected to compressive strain deformation until the strain amount was 10%. A bottle with no crack in the body after compression strain deformation was marked with a circle, and a bottle with a crack in the body during strain deformation was marked with x. The results are shown in Table 3.

Comparative Example 4 The above-mentioned polylactic acid was used. Using an injection molding machine, under conditions of 190 to 200 ° C., a nozzle diameter of 28
A preform of mmφ was injection molded. Mold temperature 15
° C. 70-75 ° C for preform using infrared heater
After reheating, a round blow bottle having a volume of 500 ml was prepared using a mold blow molding machine. 30K compressed air pressure during blow
g / cm ² constant pressure blow molding was performed. Using a 10 mmφ flat jig, the body (transverse direction) of the above molding die blow bottle was subjected to compressive strain deformation with a strain amount of 10%. A bottle with no crack in the body after compression strain deformation was marked with a circle, and a bottle with a crack in the body during strain deformation was marked with x. The results are shown in Table 3.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

Next, the preparation and measurement of samples were shown in Examples and Comparative Examples relating to the stretch moldability of an aliphatic polyester having a hard carbon film formed thereon.

(Bottle molding) A preform having a diameter of 28 mmφ was injection-molded from polylactic acid at 190 ° C. to 200 ° C. using an injection molding machine. Mold temperature 15 ° C. Next, the preform was reheated to 65 to 75 ° C. with an infrared heater, and a 500 ml-thick mold blow bottle having an average thickness of 300 μm was prepared using a mold blow molding machine. in this case,
A compressed air blowing port and an exhaust port were provided side by side, and the initial compressed air pressure was set to 30 kg / cm ^2, and then the pressure was reduced stepwise within the blowing time. Final blow pressure of 0.5 kg / cm
^The mold blow molding of No. ² was performed. Also, set the blow pressure to 3
Die blow molding was performed at a constant pressure of 0 kg / cm ² .

(Sheet forming) The polylactic acid was extruded using an extruder, and the temperature of C1 to C4 of the screw portion was increased to 190 ° C to 200 ° C.
℃, T die temperature was 190 ℃, 200mm width, 2m
An m-thick sheet was formed. Then, it was reheated to 65 ° C. to 75 ° C. using a heating oven, and 3 × 3 times biaxial stretching was performed using a modified tenter-type biaxial stretching machine (average wall thickness: 200 μm). In this case, the initial stretching speed is 1 m /
min, and the stretching speed was gradually reduced to 0.05 m / min until a predetermined stretching ratio was reached. In addition, constant-speed stretching was performed at a stretching speed of 1 m / min.

(Formation of Carbon Film) (Bottle) Using a bottle-shaped electrode and an electrode installed inside the bottle, the pressure inside the bottle was reduced by vacuum using a CVD deposition apparatus, and a mixed gas of hexane and argon was mixed with the raw material gas. The deposition pressure was 0.1 torr,
PE-CVD carbon film deposition at a high frequency power of 13.56 MHz was performed. Film formation temperature 25 ° C. (Stretched sheet) Using a plate electrode set up and down in a vacuum chamber, using a mixed gas of hexane and argon as a source gas, a film forming pressure of 0.1 torr, and a high frequency power of 13.56 MH
z-PE-CVD carbon film deposition was performed. Film forming temperature 25
° C.

(Oxygen Gas Barrier Property) (Bottle) A prototype bottle was placed in a vacuum chamber, and after depressurizing the vacuum, high-purity nitrogen gas was flowed in, and the gas phase in the bottle was replaced with nitrogen gas. Then, it sealed with the rubber stopper. It was stored under conditions of 30 ° C.-80% RH with an oxygen concentration of 20.9%. After 3 weeks, using a gas-tight syringe, it was taken the bottle in the air, and GC analysis, in terms of BO _2. (Stretched sheet) Using a gas transmission tester manufactured by Mocon,
At 40 ° C., the oxygen permeability was measured and converted to an oxygen permeability coefficient.

(Mechanical Strength) (Bottle) A compression strain test was performed with a strain amount of 10% using a 10 mmφ jig on the bottle body (horizontal direction) after the mold blow bottle and the carbon thin film were deposited. A bottle in which cracks were generated in the body direction during strain deformation was rated as x, and a bottle in which cracks did not occur during deformation was rated as ○. (Stretched sheet) Using a biaxially stretched sheet, ASTM-1 is applied to a direction having an axis in the stretching axis direction (X, Y) and a direction having an axis in a diagonal direction (45 °) formed by the stretching two axes.
An 822 type dumbbell was cut out, and a tensile stress-strain curve was obtained using a tensile tester manufactured by ORIENTEC.

Example 4 A preform having a diameter of 28 mmφ was injection molded from polylactic acid at 190 ° C. to 200 ° C. using an injection molding machine. Mold temperature 15 ° C. Next, the preform was reheated to 65 ° C. to 75 ° C. with an infrared heater, and then a 500 ml volume blow mold bottle having an average thickness of 300 μm was prepared using a mold blow molding machine. in this case,
A compressed air blowing port and an exhaust port were provided side by side, and the initial compressed air pressure was set to 30 kg / cm ^2, and then the pressure was reduced stepwise within the blowing time. Final blow pressure of 0.5 kg / cm
^The mold blow molding of No. ² was performed. Next, using a bottle-shaped electrode and an electrode placed inside the bottle, the pressure inside the bottle was reduced by vacuum, and a hexane / argon mixed gas was used as a source gas.
PE-CVD carbon film deposition at a high frequency power of 13.56 MHz was performed. Film formation temperature 25 ° C. BO ₂ obtained by storing the bottle after depositing the carbon film at 40 ° C.-RH 80% with an oxygen concentration of 20.9% was obtained. Furthermore, it is 10m in the bottle body (lateral direction)
Using a jig of mφ, a compressive strain test of a strain amount of 10% was performed. A bottle in which cracks were generated in the body direction during strain deformation was rated as x, and a bottle in which cracks did not occur during deformation was rated as ○. Table 4 shows the obtained results.

Comparative Example 5 A preform having a diameter of 28 mmφ was injection-molded from polylactic acid at 190 ° C. to 200 ° C. using an injection molding machine. Mold temperature 15 ° C. Next, the preform was reheated to 65 ° C. to 75 ° C. with an infrared heater, and then a 500 ml volume blow mold bottle having an average thickness of 300 μm was prepared using a mold blow molding machine. in this case,
A compressed air blowing port and an exhaust port were provided side by side, and the initial compressed air pressure was set to 30 kg / cm ^2, and then the pressure was reduced stepwise within the blowing time. Final blow pressure of 0.5 kg / cm
^The mold blow molding of No. ² was performed. After replacing the bottle with nitrogen, the bottle was stored at 30 ° C.-RH 80% with an oxygen concentration of 20.9% to obtain a bottle BO ₂ . Further, a compression strain test with a strain amount of 10% was performed using a 10 mmφ jig in the bottle body (lateral direction). A bottle in which cracks were generated in the body direction during strain deformation was rated as x, and a bottle in which cracks did not occur during deformation was rated as ○. Table 4 shows the obtained results.

[Comparative Example 6] A preform having a diameter of 28 mm was injection molded from polylactic acid at 190 ° C to 200 ° C using an injection molding machine. Mold temperature 15 ° C. Next, the preform was reheated to 65 ° C. to 75 ° C. with an infrared heater, and then a 500 ml volume blow mold bottle having an average thickness of 300 μm was prepared using a mold blow molding machine. in this case,
Die blow molding was performed at a constant compressed air pressure of 30 kg / cm ² . Next, using a bottle-shaped electrode and an electrode placed inside the bottle, the pressure inside the bottle was reduced by vacuum, and a hexane / argon mixed gas was used as a source gas. Electric power 1
A 3.56 MHz PE-CVD carbon film was deposited. Film formation temperature 25 ° C. After depositing the carbon film, the bottle is
To obtain a BO ₂ bottles obtained and stored in 0.9% 30 ℃ -RH80%. In addition, the bottle body (lateral direction)
Using a jig of φ, a compression strain test with a strain amount of 10% was performed. A bottle in which cracks were generated in the body direction during strain deformation was rated as x, and a bottle in which cracks did not occur during deformation was rated as ○.
Table 4 shows the obtained results.

Example 5 Using a polylactic acid extruder, the temperature of C1 to C4 in the screw portion was increased to 190 ° C to 200 ° C.
℃, T die temperature was 190 ℃, 200mm width, 2m
An m-thick sheet was formed. Then, it was reheated to 65 ° C. to 75 ° C. using a heating oven, and 3 × 3 times biaxial stretching was performed using a modified tenter-type biaxial stretching machine (average wall thickness: 200 μm). In this case, the initial stretching speed is 10 m
/ Min, and the stretching speed was gradually reduced to 0.05 m / min until a predetermined stretching ratio was reached. Next, using flat electrodes set up and down in the vacuum chamber, hexane
Deposition pressure 0.1 to using argon mixed gas as source gas
rr, PE-CVD carbon film deposition at a high frequency power of 13.56 MHz was performed. Film formation temperature 25 ° C. Further, the oxygen permeability was measured at 40 ° C. using a gas permeation tester manufactured by Mocon and converted to an oxygen permeability coefficient. Further, ASTM-1 is applied to a direction about the stretching axis direction (X, Y) and a direction about the diagonal direction (45 °) between the stretching axes.
An 822 type dumbbell was cut out, and a tensile stress-strain curve was obtained using a tensile tester manufactured by ORIENTEC. Table 5 shows the obtained results.

[Comparative Example 7] The polylactic acid was extruded by using an extruder, and the C1 to C4 temperature of the screw portion was increased to 190 ° C to 200 ° C.
℃, T die temperature was 190 ℃, 200mm width, 2m
An m-thick sheet was formed. Then, it was reheated to 65 ° C. to 75 ° C. using a heating oven, and 3 × 3 times biaxial stretching was performed using a modified tenter-type biaxial stretching machine (average wall thickness: 200 μm). In this case, the initial stretching speed is 10 m
/ Min, and the stretching speed was gradually reduced to 0.05 m / min until a predetermined stretching ratio was reached. Using the above stretched sheet, using a gas transmission tester manufactured by Mocon, 40
The oxygen permeability was measured under the condition of ° C., and was converted into the oxygen permeability. Furthermore, ASTM-1822 type dumbbells are cut out in a direction about the stretching axis direction (X, Y) and a direction about the diagonal direction (45 °) formed by the stretching two axes, respectively.
A tensile stress-strain curve was obtained with a tensile tester manufactured by ORIENTEC. Table 5 shows the obtained results.

[Comparative Example 8] Polylactic acid was used in an injection molding machine, and the C1 to C4 temperature of the screw portion was set to 190 ° C to 200 ° C.
℃, T die temperature was 190 ℃, 200mm width, 2m
An m-thick sheet was formed. Thereafter, the film was reheated to 65 ° C. to 75 ° C. using a heating oven, and 3 × 3 times biaxial stretching was performed using a modified tenter type biaxial stretching machine (average thickness: 200 μm). The speed was a constant stretching speed of 10 m / min. Next, using a bottle-shaped electrode and an electrode placed inside the bottle, the pressure inside the bottle was reduced by vacuum, and a hexane / argon mixed gas was used as a source gas. 13.56MHZ
z-PE-CVD carbon film deposition was performed. Film forming temperature 25
° C. Using the stretched sheet, the oxygen permeability coefficient was measured at 40 ° C. using a gas permeability tester manufactured by Mocon, and converted to the elemental permeability coefficient. Furthermore, a direction having the stretching axis direction (X, Y) as an axis, and a diagonal direction (45 °) formed by the two stretching axes.
ASTM-1822 type dumbbells were cut out in the directions around the axis, and a tensile stress-strain curve was obtained using a tensile tester manufactured by ORIENTEC. Table 5 shows the obtained results.

[0074]

[Table 4]

[0075]

[Table 5]

[0076]

According to the present invention, a stretch molded product of an aliphatic polyester is obtained by performing a biaxial stretching operation in which the initial stretching speed is high and the final stretching speed is low and the stretching speed is provided with a negative gradient. Is in a range satisfying the above formula (1), the anisotropy of the mechanical strength is eliminated or reduced, and the improvement of the anisotropy is caused by the degree of orientation (Do) of 0.1.
Achieved in the region of 5 or more. The container made of the stretch molded article of the present invention has an advantage that it is excellent in buckling resistance and drop impact resistance, and is effectively prevented from being cracked due to expansion / contraction or deformation. Further, by forming a hard carbon film on the aliphatic polyester stretched molded article by chemical vapor deposition (CVD), the gas permeation resistance is improved,
In addition, the sorption of low molecular organic components can be suppressed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the draw ratio (axial draw ratio, area draw ratio) and the orientation crystallinity (Do) obtained for various stretch-formed products of an aliphatic polyester stretch-formed product.

FIG. 2: ¹³ C wide NM of unoriented aliphatic polyester
The R spectrum pattern was shown.

FIG. 3 shows that the orientation axis is perpendicular to the direction of the static magnetic field of NMR.
When the aliphatic polyester ¹³C wide NMR spec
A tor pattern was shown.

FIG. 4 shows that the orientation axis is parallel to the direction of the static magnetic field of NMR.
When the aliphatic polyester ¹³C wide NMR spec
A tor pattern was shown.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B29L 7:00 9:00 F term (Reference) 3E033 AA08 BA17 BB04 BB05 BB08 EA10 FA02 FA03 GA02 GA03 4F100 AA37B AA37C AK41A BA02 BA03 BA06 BA10A BA10B BA10C EH66B EH66C EH662 EJ38 EJ381 GB16 JA05A JA11A JC00 JD02 JK02A JK10 JK20 JM02B JM02C YY00A 4F208 AA24C AE01 AG01 AG03 AG07 LA02 LB01 L0728AG01A07Q01 AG01 QN04

Claims (8)

[Claims] In a method for producing an aliphatic polyester stretched molded article, which comprises biaxially stretching a preformed article of a resin mainly composed of an aliphatic polyester, the biaxial stretching of the preformed article is performed at an initial stretching speed. A method for producing a stretch-molded article, characterized in that molding is performed while providing a negative gradient in the stretching speed so that the stretching speed is large and the final stretching speed is low. 2. A method for producing a stretch molded article, comprising forming a hard carbon film on at least one surface of the formed aliphatic polyester stretch molded article by a chemical vapor deposition method. 3. A stretched molded article formed from a resin mainly composed of an aliphatic polyester, the following equation (1) T in ₄₅ ≦ Tx ‥ (1) formula, Tx is biaxially oriented direction of the molded body Aliphatic having a tensile yield point strength (MPa), wherein T ₄₅ is a tensile yield point strength (MPa) in a direction of 45 ° with respect to the stretching direction of the molded article, Polyester stretch molded article. 4. The following formula (2): Do = (S—Sa) / S ‥ (2) In the formula, S represents a peak area of 100 to 300 ppm of chemical shift when a molded sample is measured by ¹³ C wide-area NMR. Wherein Sa represents the peak area of an NMR spectrum when the amorphous powder of the sample is measured in the same manner as described above, and the degree of orientational crystallinity (Do) is 0.15 or more. The stretch molded article according to claim 3, wherein 5. An aliphatic polyester having a glass transition point (T
The stretch molded article according to claim 3 or 4, wherein g) is an aliphatic polyester having a temperature of -60 ° C or higher. 6. The method according to claim 3, wherein the aliphatic polyester is a polyhydroxyalkanoate.
The stretched molded article according to the above. 7. The stretched molded article according to claim 3, wherein a hard carbon film is formed on at least one surface of the aliphatic polyester stretched molded article. 8. A packaging container comprising the stretched molded article according to claim 3.