JP2015042557A - Transparent container for liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a container formed of polyethylene, and excellent in transparency, heat resistance, gas barrier property, and clean property.SOLUTION: Provided is the transparent container for liquid formed of polyethylene, and satisfying requirements of (A)-(C), (A) the container has 55% or more of light transmittance after being subjected to high pressure steam sterilization in a condition of 115°C or more, (B) the container has a dimension change ratio of 7.0% or less after being subjected to high pressure steam sterilization in a condition of 115°C or more, (C) the container has 0.2wt% or less of loss weight after filling water and then leaving the container for 14 days.

Description

  The present invention relates to a container filled with a food or medical drug solution. More specifically, the present invention relates to a container made of polyethylene and having excellent transparency, heat resistance, gas barrier properties, cleanliness, and the like.

  Containers for filling foods, medical chemicals, and the like by blow-molding thermoplastic resins such as polyethylene resins have been produced. Since foods and medical chemicals directly taken into the body are strictly required to be kept in a sterile state, conventionally, a process of washing the inner wall after blow molding a thermoplastic resin into a container has been performed. Recently, a simultaneous filling blow molding method in which a liquid is filled at the same time as blow molding has been developed in order to omit the cleaning step for the purpose of improving productivity. However, in the simultaneous filling blow molding, since the liquid is injected into the molten resin container, the number of fine particles in the liquid, which is considered to be caused by the organic matter in the molten resin, is increased as compared with the conventional post-filling method. Therefore, a reduction in the number of fine particles, that is, low elution (cleanness) has been required for these containers. Furthermore, when commercialization is required, transparency to the extent that the liquid level of the content liquid can be confirmed and good blow moldability are required. Low-density polyethylene obtained by high-pressure radical polymerization is widely used as a material that satisfies these requirements. Has been used.

  In recent years, in order to further enhance safety, it has been required to set a high heat sterilization temperature for products filled with liquid. However, at high sterilization temperatures exceeding 115 ° C., if high-pressure low-density polyethylene having a melting point of about 110 ° C. is used, the container is deformed and cannot be commercialized. Furthermore, the content of the liquid filled in the simultaneous filling blow container is generally a relatively small amount, and many types are used once. That is, when the water vapor barrier property is low, a change in the concentration of the contents and a change in the volume of the internal volume cannot be ignored. Therefore, a material having a high gas barrier property in the category of polyethylene resin is required. In order to improve gas barrier properties and heat resistance, it is effective to use high-density polyethylene obtained by a low-pressure coordination anionic polymerization method with high crystallinity. However, it is well known that general high density polyethylene is inferior in transparency and blow moldability. Under these circumstances, in order to produce polyethylene containers satisfying conflicting heat resistance, gas barrier properties and transparency, and blow moldability, there are various resin compositions and multilayer containers mainly composed of high-pressure low-density polyethylene. It has been proposed (for example, see Patent Documents 1, 2, 3, and 4). In addition, a method of improving a polypropylene having excellent heat resistance and producing a container having excellent transparency and cleanliness has been proposed (see, for example, Patent Documents 5 and 6). Furthermore, the present inventors produced a macromonomer having a low molecular weight, and by using a copolymer having a long chain branch produced by a method of copolymerizing the obtained macromonomer and ethylene, transparency, heat resistance It has been found that it is possible to provide a medical container having excellent properties and cleanliness (for example, see Patent Document 7).

JP 11-49820 A JP 2002-265705 A Japanese Patent Laid-Open No. 2005-007888 JP 2008-018063 A JP 2006-306476 A JP 2012-046692 A JP 2006-314490 A

However, in the methods proposed in the above Patent Documents 1, 2, 3, and 4, the use of a multi-layer molding machine or a process for forming a resin composition is required, so that an increase in production cost and multi-components are used. For this reason, there are problems such as variations in quality that can occur. In addition, in the methods proposed in Patent Documents 5 and 6, an additive such as an antioxidant must be added to use polypropylene that is inherently easily oxidized, which is a clean property. This leads to a decline, and improvements are required. Further, in the method proposed in Patent Document 7, since it was necessary to synthesize and isolate a macromonomer and copolymerize ethylene and the macromonomer, when the molecular weight of the macromonomer is high, a copolymer of ethylene and the macromonomer Is difficult to obtain, and the molecular weight of the macromonomer has to be reduced. For this reason, through further research by the present inventors, the resulting container has poor mechanical strength due to the high molecular weight of polyethylene, resulting in inconveniences such as tearing when assembling parts and damage during transportation. It has become difficult to apply.

As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention consisted of polyethylene obtained by sequentially synthesizing a macromonomer and copolymerizing ethylene and the macromonomer without synthesizing and isolating the macromonomer. The inventors have found that the balance of transparency, heat resistance, gas barrier properties, cleanliness and mechanical strength of the container is excellent, and have completed the present invention. That is, the present invention relates to a transparent container for liquid, which is a container made of polyethylene and satisfies the following requirements (A), (B), (C), and (D).
(A) Light transmittance after autoclaving at 115 ° C. or higher is 55% or more (B) Dimensional change rate after autoclaving at 115 ° C. or higher is 7.0% or less (C ) Filled with water and left to stand for 14 days, weight loss (weight loss weight ratio) is 0.2 wt% or less (D) -20 ° C puncture impact strength is 2.0 kJ / m or more. Permeability is in accordance with the Japanese Pharmacopoeia, set a transparent container for liquid in the autoclave by high-pressure steam sterilization, sterilize at a temperature of 115 ° C. for 30 minutes, 9.5 mm wide from the sterilized container, A sample piece having a length of 50 mm is cut out and the light transmittance at a wavelength of 450 nm is measured in pure water.

  (B) Dimensional change rate means that a sample piece having a width of 50 mm and a length of 50 mm is cut out from a molded container, subjected to high-pressure steam sterilization by the same method as described above, and the width (W) and length ( L) is measured, and the average dimensional change rate in the width direction and the length direction is obtained from the following equation.

Dimensional change rate (%) = 100 × {(50−W) / 50 + (50−L) / 50} / 2
(C) The weight loss percentage (%) is the weight of a sealed transparent container for water filled with water (weight A), then 14% at a relative humidity of 65 ± 5% and a temperature of 20 ± 2 ° C. The weight after standing for days was measured (weight B), and it was obtained from the following formula.

Weight loss ratio (%) = 100 × (weight A−weight B) / weight A
(D) Puncture impact strength is in accordance with JIS P8134. A sample piece having a width of 100 m and a length of 100 mm is cut out from a molded container, treated at a temperature of −20 ° C. for 10 minutes, and fixed to a puncture impact tester. In this case, it is pierced from the lower surface of the film with a triangular pyramid impact head having an angle of 60 degrees, and the breaking energy at that time is measured.

  The container of the present invention has a light transmittance of 55% or more, preferably 60% or more after autoclaving at 115 ° C. or higher. When the light transmittance is lower than 55%, it is difficult to visually confirm the liquid level of the content liquid, and the Japanese Pharmacopoeia standard value cannot be achieved. Moreover, the dimensional change rate after autoclaving at 115 ° C. or higher is 7.0% or less, and preferably 5% or less. When the dimensional change rate is higher than 7.0%, the container after sterilization is clearly deformed visually, making it difficult to produce a product. Further, the weight to be reduced after filling with water and leaving it to stand for 14 days is 0.2 wt% or less, preferably 0.1 wt% or less. When the weight to be reduced after filling with water and leaving for 14 days exceeds 0.2 wt%, the concentration change of the contents after long-term storage cannot be ignored, so it cannot be used as a small-capacity food or medical container In addition, the Japanese Pharmacopoeia standard values cannot be achieved. Furthermore, the puncture impact strength at −20 ° C. is 2.0 kJ / m or more, preferably 3.0 kJ / m or more. When the puncture impact strength at −20 ° C. is lower than 2.0 kJ / m, when the content liquid is filled and dropped after storage at low temperature, the content may leak.

The container of the present invention is filled with pure water whose fine particles of 1 μm or more are confirmed to be 0/10 ml, and has a number of fine particles of 2 μm or more measured after autoclaving at 115 ° C. or higher. It is preferable that it is 30 / 10ml or less, and it goes without saying that the standard value of the Japanese Pharmacopoeia can be achieved within this range, and there can be no problem when used for medical containers, food containers, etc. Hygiene can be secured. Moreover, it is preferable that the weight (n-heptane extraction amount) of the component extracted when immersed in heptane at 50 ° C. for 2 hours is 0.2 wt% or less, and in this range, the low molecular weight component having poor heat resistance However, it is difficult for bleeding to occur on the surface of the container and blocking is unlikely to occur. Further, the oxygen permeability coefficient measured at 23 ° C. and 100 kPa is preferably 6 × 10 ⁻¹⁶ (mol × m) / (m ² × s × Pa) or less in accordance with JIS K7126-1. If present, the barrier property is clearly higher than that of an existing high-pressure low-density polyethylene container, and it is possible to secure a barrier property that, when used as a container, the concentration change of the contents cannot become a practical problem.

Polyethylene constituting the container of the present invention, the density conforming to JIS K6760 is not more 925 kg / ^{m 3} or more 955 kg / ^{m 3} or less, preferably 930 kg / ^{m 3} or more 950 kg / ^{m 3} or less, more preferably 935 kg / m ³ or more and 945 kg / m ³ or less, and the melt flow rate (MFR) measured at 190 ° C. under a load of 2.16 kg in accordance with ASTM 1238 is 0.1 g / 10 min or more and less than 10 g / 10 min, preferably Is 0.6 g / 10 min or more and less than 5 g / 10 min, in a DSC crystallization exothermic curve obtained by measuring the temperature from 220 ° C. to 40 ° C. at 40 ° C./min with a differential scanning calorimeter (DSC). The difference between the temperature at which crystallization starts (Tc onset) and the temperature at which the crystallization exotherm reaches a maximum (Tc peak) is 10 ° C. or more, An ethylene / α-olefin copolymer having a DSC melting endotherm curve obtained by measuring from 0 ° C. to 220 ° C. at a rate of 10 ° C./min and showing a peak, and having strain-hardening properties of elongational viscosity during melt stretching. Coalescence is preferred. When the density is 925 kg / m ³ or more, the container can be suitably used as a heat-resistant container without deformation of the container or a decrease in transparency during high-temperature sterilization. When the density is 950 kg / m ³ or less, transparency and mechanical strength that are practically acceptable as a transparent container for liquid can be obtained. Further, if the MFR is in the range of 0.1 g / 10 min or more and less than 10 g / 10 min, the extrusion load at the time of extrusion can be molded without excessively high, and the drawdown resistance is good. Blow molding is possible without problems. Further, in the DSC crystallization exothermic curve obtained by measuring by DSC at a rate of 40 ° C./min from 220 ° C. to 40 ° C., the difference between the Tc onset and the Tc peak is 10 ° C. or more. When the DSC melting endothermic curve obtained by measuring the temperature up to 220 ° C. at a rate of 10 ° C./min shows one peak, the transparency is improved during cooling after molding. Furthermore, by exhibiting strain-hardening properties of elongational viscosity at the time of melt stretching, the drooping of the molten resin is reduced, the thickness variation of the molded product is eliminated, and a container having a good shape is obtained. Further, when the polyethylene has a melt tension of 40 mN or more, deformation during extrusion molding becomes small, the product shape can be easily controlled, and a container can be obtained stably.

  The polyethylene used in the present invention is produced using a metallocene catalyst. The metallocene catalyst to be used has a metallocene complex, an activation cocatalyst, and, if necessary, an organoaluminum compound as constituents. At the same time as the synthesis of the macromonomer, the macromonomer, ethylene and an olefin having 3 to 6 carbon atoms are copolymerized. It is preferable to carry out.

  The macromonomer is an olefin polymer having a vinyl group at the terminal, and is an ethylene copolymer having a vinyl group at the terminal obtained by copolymerizing ethylene and an olefin having 3 to 6 carbon atoms. Non-bridged bis (indenyl) zirconium complexes and non-bridged bis (cyclopentadienyl) as metallocene complexes of metallocene catalysts that synthesize macromonomers and copolymerize macromonomers, ethylene and olefins having 3 to 6 carbon atoms Zirconium complex, bridged bis (cyclopentadienyl) zirconium complex, bridged bis (indenyl) zirconium complex, bridged (cyclopentadienyl) (indenyl) zirconium complex, bridged (cyclopentadienyl) (fluorenyl) zirconium A catalyst using a complex or a bridged (indenyl) (fluorenyl) zirconium complex is preferred. With these complexes, the synthesis of the macromonomer and the copolymerization of the macromonomer, ethylene, and olefin having 3 to 6 carbon atoms can be carried out with one kind of complex, and a polyethylene having a Tc peak difference of 10 ° C. or more can be obtained. Can be obtained. Specific examples of metallocene complexes include, for example, bis (indenyl) zirconium dichloride, dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (indenyl) zirconium dichloride, dimethylsilanediyl (cyclopenta). Dienyl) (2-methylindenyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (4,7-dimethylindenyl) zirconium dichloride, dimethylsilanediyl (cyclopentadienyl) (2,4,7- Trimethylindenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopenta Dichlorides such as enyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, isopropylidene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride Examples of the transition metal compound include dimethyl, diethyl, dihydro, diphenyl, and dibenzyl. Moreover, although the compound which substituted the zirconium atom of the said transition metal compound with the titanium atom or the hafnium atom can also be illustrated, it is not limited to these. Among these, you may use 1 type or multiple types.

  The activation co-catalyst used as a component of the metallocene catalyst is a metallocene complex or a compound that plays a role in converting a reaction product of a metallocene complex and an organoaluminum compound into an active species capable of olefin polymerization. It is preferable that it is a compound which produces | generates a reactive compound, and the produced | generated cationic compound acts as a polymerization active seed | species which can superpose | polymerize an olefin. An activation co-catalyst is a compound that provides a compound that, after forming a polymerization active species, coordinates weakly or interacts with the generated cationic compound, but does not react directly with the active species.

  Specific examples of the activation promoter include alkylaluminoxanes such as methylaluminoxane, silica gel-supported alkylaluminoxanes, tris (fluorinated aryl) borons such as tris (pentafluoreophenyl) boron, N, N-dimethylammonium-tetrakis ( Examples thereof include boron compounds such as tetrakis (fluorinated aryl) boron salts such as pentafluorophenyl) boron, silica gel-supported materials thereof, clay minerals, clay minerals treated with organic compounds, and the like. Among them, it is preferable to use a clay mineral treated with an organic compound.

  When a clay mineral treated with an organic compound is used as the activation promoter, the clay mineral used is preferably a clay mineral belonging to the smectite group, and specific examples include montmorillonite, beidellite, saponite, hectorite and the like. It is also possible to use a mixture of a plurality of these clay minerals.

  The organic compound treatment means introducing an organic ion between clay mineral layers to form an ionic complex. Examples of the organic compound used in the organic compound treatment include N, N-dimethyl-n-octadecylamine hydrochloride, N, N-dimethyl-n-eicosylamine hydrochloride, N, N-dimethyl-n-docosylamine hydrochloride, N, N-dimethyloleylamine hydrochloride, N, N-dimethylbehenylamine hydrochloride, N-methyl-bis (n-octadecyl) amine hydrochloride, N-methyl-bis (n-eicosyl) amine hydrochloride, N-methyl -Alkylammonium salts such as dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, N, N-dimethylaniline hydrochloride can be exemplified.

  The metallocene catalyst is not particularly limited in the method for preparing the metallocene catalyst such as a method in which a metallocene complex is reacted with an activation promoter.

  As the metallocene catalyst, an alkylaluminum such as triethylaluminum or triisobutylaluminum may be used as necessary for the activation of the metallocene complex and the removal of impurities in the solvent during the preparation of the catalyst.

  When the polyethylene used in the present invention is produced, it is preferably carried out at a polymerization temperature of −100 to 120 ° C., preferably 20 to 120 ° C. in view of productivity, and more preferably in the range of 60 to 120 ° C. It is preferable. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa. The polymerizable monomer is ethylene and an α-olefin having 3 to 6 carbon atoms, and the supply ratio of ethylene and the α-olefin having 3 to 6 carbon atoms is ethylene / α-olefin having 3 to 6 carbon atoms ( A feed ratio of 1 to 200, preferably 3 to 100, and more preferably 5 to 50 can be used. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. The ethylene / α-olefin copolymer can be separated and recovered from the polymerization solvent by a conventionally known method after completion of the polymerization, and dried to obtain.

  The polymerization can be carried out in a slurry state, a solution state or a gas phase state. In particular, when the polymerization is carried out in a slurry state, polyethylene having a powder particle shape can be produced efficiently and stably.

The MFR in the present invention can be measured at a temperature of 190 ° C. and a load of 2.16 kg in accordance with ASTM 1238. For the strain hardening, the maximum value of the extension viscosity measured at 160 ° C. and the strain rate of 0.07 to 0.1 s ⁻¹ using a Meissner type uniaxial extension viscometer is the extension viscosity in the linear region at that time. The value divided by is defined as a non-linear parameter λ, and when λ exceeds 1, it can be confirmed that there is strain hardening. Note that M.M. Yamaguchi et al. Polymer Journal 32, 164 (2000). As described in, the elongational viscosity in the linear region can be calculated from dynamic viscoelasticity. When λ is 1, it can be determined that there is no strain hardening. In addition, (trade name) Capillograph (manufactured by Toyo Seiki Seisakusho) is used for melt tension. A strand lowered at a piston lowering speed of 10 mm / min is drawn at 10 m / min from a die having a length (L) of 8 mm and a diameter (D) of 2.095 mm at 190 ° C., and the take-up load is measured as a melt tension. Can do.

  The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by GPC of polyethylene constituting the container of the present invention is preferably 3.0 to 6.0, more preferably 3.5. ~ 5.5. When Mw / Mn is within this range, good product appearance and moldability can be obtained, which is preferable. Mn is preferably 15,000 or more, more preferably 15,000 to 100,000, and particularly preferably 15,000 to 50,000. When Mn is 15,000 or more, the mechanical strength of the resulting container increases.

  In the polyethylene used in the present invention, an inorganic filler such as a heat stabilizer, a weather stabilizer, an antistatic agent, an antiblocking agent, a slip agent, a lubricant, a nucleating agent, and a pigment, or an organic filler, as long as the cleanliness is not deteriorated. Known additives such as an agent or a reinforcing agent can be blended. Moreover, it can also be used by mixing with other thermoplastic resins. Examples of these include high density polyethylene (HDPE), linear low density polyethylene (L-LDPE), high pressure process low density polyethylene (LDPE), polypropylene resin, poly-1-butene, poly-4-methyl-1 Examples include pentene, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, polystyrene, and maleic anhydride grafts thereof.

  Examples of the container sterilization method include an EOG sterilization method, a high-pressure steam (autoclave) sterilization method, and a radiation irradiation sterilization method. The thickness of the container is preferably 0.05 to 2 mm, more preferably 0.1 to 0.8 mm, and most preferably 0.15 to 0.6 mm. The high-pressure steam sterilization method is a method of sterilization by heating for a certain period of time using saturated water vapor that has been pressurized to increase its temperature. This method is performed at 115 ° C. for 30 minutes at 121 ° C. in the Japanese Pharmacopoeia. The conditions for 20 minutes or at 126 ° C. for 16 minutes are determined, and the processing conditions are determined by the material quality of the product, the safety of the product after sterilization, and the like. is there.

  The container obtained by the present invention has an excellent balance of transparency, heat resistance, gas barrier properties, and cleanness, and is suitable for containers filled with various foods and medical chemicals.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Below, the evaluation method of the container used by the Example and the comparative example is shown.
~ Container evaluation ~
~ Evaluation of formability ~
The container manufactured by the method shown in Example 1 was visually observed, and the presence or absence of uneven thickness due to poor drawdown property of the molten parison was evaluated.

~ Evaluation of transparency ~
In accordance with the Japanese Pharmacopoeia, the container manufactured by the method shown in Example 1 was set in the autoclave by high-pressure steam sterilization, and the container sterilized at 115 ° C. for 30 minutes was taken out. Using a “UV-visible spectrophotometer 220A” manufactured by Hitachi, a sample piece having a width of 9.5 mm and a length of 50 mm was cut out from the sterilized container, and the light transmittance at a wavelength of 450 nm was measured in pure water.

~ Evaluation of heat resistance ~
A sample piece having a width of 50 mm and a length of 50 mm was cut out from the molded container and subjected to high-pressure steam sterilization in the same manner as described above. The width (W) and length (L) of the sample piece after sterilization were measured, and the average dimensional change rate in the width direction and the length direction was obtained from the following formula.

Dimensional change rate (%) = 100 × {(50−W) / 50 + (50−L) / 50} / 2
-Evaluation of moisture permeability-
The container manufactured by the method shown in Example 1 was filled with water, and the weight of the sealed container was weighed (weight A), and then the weight after being left for 14 days at a relative humidity of 65 ± 5% and a temperature of 20 ± 2 ° C. Was weighed (weight B). The weight loss weight ratio obtained by the following formula was used as an index of moisture permeability.

Weight loss ratio (%) = 100 × (weight A−weight B) / weight A
~ Evaluation of impact resistance ~
In accordance with JIS P8134, a sample piece having a width of 100 m and a length of 100 mm is cut out from a molded container, treated at a temperature of −20 ° C. for 10 minutes, fixed to a puncture impact tester, and a triangular pyramid impact head with an angle of 60 degrees. Was pierced from the lower surface of the film, and the breaking energy at that time was measured.

-Evaluation of fine particles-
After 100 ml of pure water and 10 ml of clean air were sealed in a container washed with pure water whose number of fine particles of 1 μm or more was confirmed to be 0/10 ml, hydrothermal sterilization was performed at 115 ° C. for 30 minutes. After standing for 1 day, the number of fine particles of 2 μm or more was measured using a fine particle counter “M-3000 · 4100 · HR-60HA” manufactured by HIAC / ROYCO. These operations were all performed in a class 1000 clean room.

-N-Heptane extract amount-
About 2 g of a sample that has been cut and crushed and passed through a 200-mesh sieve, weighed precisely, added 400 ml of n-heptane, extracted at 50 ° C. for 2 hours, evaporated the solvent from the extract, and dried. It calculated by calculating | requiring the ratio with respect to the initial weight of the weight of the extract obtained by solidifying.

~ Low temperature drop test ~
The container was cooled in a −20 ° C. freezer for 24 hours. The container was dropped from a height of 1 m onto the concrete surface.

10 out of 10 no cracks ... ○,
2 to 3 out of 10 cracks, cracks, etc ...
5 out of 10 cracks, cracks, etc ...
-Production and evaluation of ethylene / α-olefin copolymers-
Although the manufacture example of the ethylene * alpha-olefin copolymer used for this invention is demonstrated concretely below, this invention is not limited to these. Unless otherwise noted, the reagents used were commercially available products or those synthesized according to known methods.

  A jet mill (trade name: CO-JET SYSTEM α MARK III, manufactured by Seishin Enterprise Co., Ltd.) was used for pulverization of the organically modified clay, and the particle size after pulverization was measured using a microtrack particle size distribution analyzer (trade name, manufactured by Nikkiso Co., Ltd.). MT3000) was used to measure ethanol as a dispersant.

  Preparation of the ethylene / α-olefin copolymer production catalyst, production of the ethylene / α-olefin copolymer and solvent purification were all carried out in an inert gas atmosphere. A hexane solution (20 wt%) of triisobutylaluminum manufactured by Tosoh Finechem Co., Ltd. was used. Furthermore, various physical properties of the ethylene / α-olefin copolymer in the examples were measured by the following methods.

~ Measurement of density ~
The density gradient tube method was used in accordance with JIS K6760 (1995).

~ Measurement of MFR ~
In accordance with ASTM 1238, the measurement was performed at a temperature of 190 ° C. and a load of 2.16 kg.

~ Measurement of characteristic crystallization temperature difference and melting point ~
It measured using the differential scanning calorimeter and "DSC-7" by Perkin Elmer. After the sample is melted at 220 ° C. for 5 minutes in the apparatus and then cooled to 40 ° C. at a cooling rate of 40 ° C./min, the temperature at the position where the exotherm of the DSC crystallization exotherm curve starts and the heat generation are maximized The difference in temperature at the indicated position was defined as a characteristic crystallization temperature difference. Further, the number of peaks in the melting endotherm curve obtained when the temperature was raised again to 220 ° C. at a rate of 10 ° C./min was measured, and the peak temperature was taken as the melting point.

~ Measurement of strain hardening ~
The measurement was performed using a Meissner type uniaxial extensional viscometer (manufactured by Toyo Seiki Seisakusho, trade name: Melten Rheometer) set at a temperature of 160 ° C. The non-linear parameter (λ) was obtained as a value obtained by dividing the maximum value of the extensional viscosity measured under the condition of strain rate of 0.07 to 0.1 s ⁻¹ by the extensional viscosity in the linear region at that time. In addition, the value of the extensional viscosity in the linear region is taken by Takeshi Fukuda, New Polymer Experimental Science 1, Basics of Polymer Experiment, Molecular Characteristic Analysis, “3-4. Molecular Shape and Form”, 295 (1994). According to the method described in the above, calculation was performed using an approximate expression from dynamic viscoelasticity. When the obtained λ exceeded 1, it was judged that there was strain hardening.

~ Measurement of melt tension (MS) ~
Capillograph (manufactured by Toyo Seiki Seisakusho) was used. A strand lowered at a piston lowering speed of 10 mm / min was drawn at 10 m / min from a die having a length (L) of 8 mm and a diameter (D) of 2.095 mm at 190 ° C., and the take-up load was taken as melt tension.

-Weight average molecular weight (Mw), number average molecular weight (Mn), ratio of weight average molecular weight to number average molecular weight (Mw / Mn)-
The weight average molecular weight (Mw), the number average molecular weight (Mn), and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) were measured by GPC. The column temperature was set to 140 ° C. using a GPC device (Tosoh Corp. (trade name) HLC-8121GPC / HT) and a column (Tosoh Corp. (trade name) TSKgel GMHhr-H (20) HT). The measurement was performed using 1,2,4-trichlorobenzene as an eluent. A measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected and measured. The calibration curve of molecular weight was calibrated using a polystyrene sample having a known molecular weight. In addition, Mw and Mn were calculated | required as a value of linear polyethylene conversion.

Production Example 1
[Production of ethylene / α-olefin copolymer (A-1)]
(1) Denaturation of clay In 6 liters of distilled water, 150 g of concentrated hydrochloric acid, 424 g (1.2 mol) of dimethylbehenylamine (Lion Co., Ltd. (trade name) Armin DM22D) and synthetic hectorite (trade name of Rockwood Additives) (trade name) After adding 1 kg of Laponite RD), the mixture was heated to 60 ° C. and stirred for 1 hour while maintaining the temperature. This slurry was filtered, washed twice with 6 liters of distilled water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 1.2 kg of modified clay. The modified clay was pulverized by jet mill to have a median diameter of 15 μm.
(2) Preparation of catalyst suspension After substituting a 5-liter flask equipped with a thermometer and a reflux tube with nitrogen, 500 g of the modified clay obtained in (1) and 3.1 liters of hexane were added, and then dimethylsilanediyl (Cyclopentadienyl) (2,4,7-trimethyl-1-indenyl) zirconium dichloride (8.81 g) and 20% triisobutylaluminum (1.4 liter) were added, and the mixture was stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was extracted, washed 5 times with 4 liters of hexane, and then added with 4 liters of hexane to obtain a catalyst suspension (solid weight: 11.0 wt%).
(3) Production of ethylene / α-olefin copolymer (A-1) In a polymerization vessel having an internal volume of 540 L, hexane was 145 kg / hour, ethylene was 30 kg / hour, butene-1 was 4.5 kg / hour, and hydrogen was added. The catalyst suspension prepared in the above (2) is continuously supplied so that the production amount is 5 NL / hour and the polymer production amount is 30 kg / hour, continuously while maintaining the total pressure at 3,000 kPa and the polymerization vessel internal temperature at 70 ° C. A polymerization reaction was performed.

The slurry was continuously extracted from the polymerization vessel to remove unreacted hydrogen, ethylene, and butene-1, and then separated and dried to obtain ethylene / α-olefin copolymer (A-1) powder. This was melt-kneaded using a single-screw extruder having a diameter of 50 mm set at 200 ° C. and pelletized to obtain ethylene / α-olefin copolymer (A-1) pellets. The density of the obtained ethylene / α-olefin copolymer (A-1) pellets was 927 kg / m ³ , MFR was 2.5 g / 10 min, characteristic crystallization temperature difference 14.5 ° C., melting point 115 ° C., strain hardening. The melt tension was 67 mN, Mn 17,000, and Mw / Mn 5.3.

Production Example 2
[Production of ethylene / α-olefin copolymer (A-2)]
(1) Modification of clay (2) Preparation of catalyst suspension The same procedure as in Production Example 1 was performed.
(3) Production of ethylene / α-olefin copolymer (A-2) A polymerizer having an internal volume of 540 L was charged with 145 kg / hour of hexane, 30 kg / hour of ethylene, 2.0 kg / hour of butene-1 and hydrogen. The catalyst suspension prepared in (2) above was continuously fed so that the production amount was 7 NL / hour and the polymer production was 30 kg / hour, and the total pressure was 3,000 kPa and the polymerization vessel internal temperature was kept at 75 ° C. A polymerization reaction was performed.

The slurry was continuously extracted from the polymerization vessel to remove unreacted hydrogen, ethylene, and butene-1, and then separated and dried to obtain ethylene / α-olefin copolymer (A-2) powder. This was melt-kneaded using a single-screw extruder having a diameter of 50 mm set at 200 ° C. and pelletized to obtain ethylene / α-olefin copolymer (A-2) pellets. The density of the obtained ethylene / α-olefin copolymer (A-1) pellets was 935 kg / m ³ , MFR 3.3 g / 10 min, characteristic crystallization temperature difference 13.8 ° C., melting point 121 ° C., strain hardening The melt tension was 57 mN, Mn 17,000, and Mw / Mn 5.6.

Production Example 3
[Production of ethylene / α-olefin copolymer (A-3)]
(1) Modification of clay (2) Preparation of catalyst suspension The same procedure as in Production Example 1 was performed.
(3) Production of ethylene / α-olefin copolymer (A-3) In a polymerization vessel having an internal volume of 540 L, hexane was 145 kg / hour, ethylene was 30 kg / hour, butene-1 was 1.2 kg / hour, and hydrogen was added. The catalyst suspension prepared in the above (2) is continuously supplied so that the production amount is 10 NL / hour and the polymer production amount is 30 kg / hour, continuously while maintaining the total pressure at 3,000 kPa and the polymerization vessel internal temperature at 75 ° C. A polymerization reaction was performed.

After continuously removing the slurry from the polymerization vessel and removing unreacted hydrogen, ethylene, and butene-1, ethylene / α-olefin copolymer (A-3) powder was obtained through steps of separation and drying. This was melt-kneaded using a single-screw extruder with a 50 mm diameter set at 200 ° C. and pelletized to obtain ethylene / α-olefin copolymer (A-3) pellets. The density of the obtained ethylene / α-olefin copolymer (A-3) pellet was 938 kg / m ³ , MFR was 0.8 g / 10 min, characteristic crystallization temperature difference 13.4 ° C., melting point 126 ° C., strain hardening The melt tension was 100 mN, Mn 25,000, and Mw / Mn 4.4.

Production Example 4
[Production of ethylene / α-olefin copolymer (A-4)]
(1) Modification of clay (2) Preparation of catalyst suspension The same procedure as in Production Example 1 was performed.
(3) Production of ethylene / α-olefin copolymer (A-4) In a polymerizer having an internal volume of 540 L, hexane was 145 kg / hour, ethylene was 30 kg / hour, butene-1 was 1.3 kg / hour, and hydrogen was added. The catalyst suspension prepared in (2) above was continuously fed so that the production amount was 7 NL / hour and the polymer output was 30 kg / hour, and the total pressure was 3,000 kPa and the polymerization vessel internal temperature was kept at 80 ° C. A polymerization reaction was performed.

The slurry was continuously extracted from the polymerization vessel to remove unreacted hydrogen, ethylene, and butene-1, and then separated and dried to obtain an ethylene / α-olefin copolymer (A-4) powder. This was melt-kneaded using a single-screw extruder with a diameter of 50 mm set at 200 ° C. and pelletized to obtain ethylene / α-olefin copolymer (A-4) pellets. The density of the obtained ethylene / α-olefin copolymer (A-4) pellets is 940 kg / m ³ , MFR is 4.0 g / 10 min, characteristic crystallization temperature difference 13.4 ° C., melting point 130 ° C., strain hardening The melt tension was 72 mN, Mn 23,000, and Mw / Mn 3.7.

Production Example 5
[Production of ethylene / α-olefin copolymer (A-5)]
(1) Denaturation of clay After adding 60 mL of ethanol and 2.0 mL of 37% concentrated hydrochloric acid to 60 mL of water, 11.7 g (0.022 mol) of N-methyldioleilamine was added to the resulting solution and heated to 60 ° C. To prepare an N-methyldioleylamine hydrochloride solution. To this solution was added 20 g of hectorite. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 1 L of 60 ° C. water. Then, it dried at 60 degreeC and 10-3 torr for 24 hours, and the modified | denatured hectorite with an average particle diameter of 5.2 micrometers was obtained by grind | pulverizing with a jet mill. As a result of elemental analysis, the amount of ions per gram of modified hectorite was 0.85 mmol.
(2) Preparation of Catalyst Suspension 8.0 g of the modified hectorite was suspended in 29 mL of hexane, 46 mL of a hexane solution of triisobutylaluminum (0.714 M) was added, and the mixture was stirred at room temperature for 1 hour. A contact product of (b) and component (c) was obtained. On the other hand, 111.5 mg (320 μmol) of dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride dissolved in toluene was added and stirred at room temperature overnight to obtain a catalyst slurry (100 g / L). .
(3) Production of Macromonomer 1,200 mL of hexane and 1.0 mL of a hexane solution of triisobutylaluminum (0.714 mol / L) were introduced into a 2 L autoclave, and the internal temperature of the autoclave was raised to 90 ° C. To this autoclave, 0.25 mL of the catalyst slurry was added, and ethylene was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, ethylene was continuously introduced so that the partial pressure was kept at 1.2 MPa. The polymerization temperature was controlled at 90 ° C. 34 minutes after the start of polymerization, the internal temperature was lowered to 50 ° C. and the internal pressure of the autoclave was depressurized to 0.1 MPa, and then nitrogen was introduced into the autoclave until the pressure became 0.6 MPa and depressurized. This operation was repeated 5 times.
(4) Production of ethylene / α-olefin copolymer (A-5) 1.0 mL of triisobutylaluminum hexane solution (0.714 mol / L) was introduced into a 2 L autoclave containing the macromonomer produced above. After adding 3 ml of butene-1, the internal temperature of the autoclave was raised to 85 ° C. After maintaining the temperature and stirring for 30 minutes, 20 mL of a toluene solution of 5 μmol of diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride was added to the autoclave, The mixture was stirred for 1 hour while maintaining the temperature. Ethylene was introduced until the partial pressure reached 0.1 MPa to initiate polymerization. During the polymerization, ethylene was continuously introduced so that the partial pressure was maintained at 0.1 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 113 g of polymer was obtained. The obtained ethylene / macromonomer copolymer had an MFR of 5.0 g / 10 min and a density of 953 kg / m ³ .

Examples 1-4
~ Manufacture of containers ~
Using a blow-fill-seal machine equipped with a blow die, the plastic ampule (internal volume 10 ml) formed by filling the ethylene / α-olefin copolymer produced in Production Examples 1 to 4 with a blow die Manufactured. This ampoule had a barrel thickness of 400 μm.

~ Sterilization of filled containers ~
The container prepared by the above method was autoclaved at 115 ° C. for 30 minutes using a high-temperature and high-pressure cooking sterilizer manufactured by Nisaka Seisakusho and cooled to room temperature.
The results are shown in Table 1.

比較例１
エチレン・α−オレフィン共重合体に代えて高圧法により製造された市販の低密度ポリエチレン（東ソー（株）製、（商品名）ペトロセン１８６；密度＝９２４ｋｇ／ｍ^３、ＭＦＲ＝３．０ｇ／１０分、特性結晶化温度差９．２℃、融点１１１℃、溶融張力９０ｍＮ、歪硬化性あり、Ｍｎ１６，０００、Ｍｗ／Ｍｎ３．９）を用いた以外は実施例１と同様に行った。結果を表２に示す。

Comparative Example 1
Commercially available low density polyethylene manufactured by high pressure method instead of ethylene / α-olefin copolymer (manufactured by Tosoh Corporation, (trade name) Petrocene 186; density = 924 kg / m ³ , MFR = 3.0 g / 10 Minute, characteristic crystallization temperature difference 9.2 ° C., melting point 111 ° C., melt tension 90 mN, strain hardening, Mn 16,000, Mw / Mn 3.9). The results are shown in Table 2.

Comparative Example 2
Commercially available low-density polyethylene (manufactured by Tosoh Corporation, (trade name) Petrocene 172; manufactured by the high-pressure method instead of the ethylene / α-olefin copolymer), density = 920 kg / m ³ , MFR = 0.3 g / This was carried out in the same manner as in Example 1 except that a characteristic crystallization temperature difference of 9.7 ° C., a melting point of 110 ° C., a melt tension of 230 mN, a strain hardening property, Mn 19,000, Mw / Mn 5.5) was used. The results are shown in Table 2.

Comparative Example 3
Commercially available linear low density polyethylene produced by using a Ziegler-Natta type catalyst instead of the ethylene / α-olefin copolymer (manufactured by Tosoh Corporation, (trade name) Nipolon-LM50; density = 936 kg / m) ³ , MFR = 3.0 g / 10 min, characteristic crystallization temperature difference 4.2 ° C., melting point 80, 116 ° C., melt tension 9 mN, no strain hardening, Mn 25,000, Mw / Mn 3.5) Was carried out in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4
Commercially available linear low density polyethylene produced by using a Ziegler-Natta type catalyst instead of the ethylene / α-olefin copolymer (manufactured by Tosoh Corporation, (trade name) Nipolon-LF13; density = 920 kg / m ³ , MFR = 0.5 g / 10 min, characteristic crystallization temperature difference 5.6 ° C., melting point 75, 120 ° C., melt tension 45 mN, no strain hardening, Mn 23,000, Mw / Mn 3.7) Was carried out in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 5
Commercially available linear low-density polyethylene produced by using a metallocene catalyst instead of ethylene / α-olefin copolymer (manufactured by Tosoh Corporation, (trade name) Nipolon-Z7P02A; density = 920 kg / m ³ , MFR) = 2.0 g / 10 min, characteristic crystallization temperature difference 5.7 ° C., melting point 113 ° C., melt tension 12 mN, no strain hardening, Mn 44,000, Mw / Mn 1.9) The same was done. The results are shown in Table 2.

Comparative Example 6
Ethylene / α-olefin copolymer A-5 produced in Production Example 5; density = 953 kg / m ³ , MFR = 5.0 g / 10 min, characteristic crystallization temperature difference 8.1 ° C., melting point 126 ° C., melt tension 120 mN, no strain hardening, Mn 8,000, Mw / Mn 8.7) The results are shown in Table 2.

Claims (8)

A transparent container for liquid, which is a container made of polyethylene and satisfies the following requirements (A) to (D).
(A) Light transmittance after autoclaving at 115 ° C. or higher is 55% or more (B) Dimensional change rate after autoclaving at 115 ° C. or higher is 7.0% or less (C ) Weight is reduced to 0.2 wt% or less after filling with water and left for 14 days. (D) Puncture impact strength at -20 ° C is 2.0 kJ / m or more The transparent container for liquid according to claim 1, wherein the number of fine particles of 2 µm or more measured after autoclaving at 115 ° C or higher is 30 / 10ml or less The transparent container for liquid according to claim 1 or 2, wherein the weight of the component extracted when immersed in heptane at 50 ° C for 2 hours is 0.2 wt% or less. The transparent container for liquid (a) JIS K6760 according to any one of claims 1 to 3, wherein the polyethylene is an ethylene / α-olefin copolymer that satisfies the following requirements (a) to (d): 925-955 kg / m ³ in accordance with the density
(B) According to ASTM 1238, the melt flow rate measured at 190 ° C. and a load of 2.16 kg is 0.1 or more and less than 10 g / 10 min. (C) 40 ° C. from 220 ° C. to 40 ° C. by a differential scanning calorimeter (DSC) In the DSC crystallization exotherm curve obtained by measuring the temperature at a rate of ℃ / min, the difference between the temperature at which crystallization starts (Tc onset) and the temperature at which the crystallization exotherm reaches a maximum (Tc peak) is 10 ° C or more. The DSC melting endotherm curve obtained by measuring the temperature from 40 ° C. to 220 ° C. at a rate of 10 ° C./min shows one peak. (D) Strain hardening property of elongational viscosity during melt drawing The liquid transparent container according to claim 1, wherein the liquid transparent container is a chemical liquid filling container obtained by simultaneous filling blow molding. The transparent container for liquid according to claim 5, wherein the transparent container for liquid is a kit preparation container. The transparent container for liquid according to claim 5, wherein the transparent container for liquid is a plastic ampule. The transparent container for liquid according to claim 5, wherein the transparent container for liquid is an eye drop container.