JP2016003018A - Blow-molded vessel and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow-molded vessel which is useful as a medical vessel, a food vessel or the like, composed of a specified block copolymer hydride, suppressed in thick deviation, and favorable in heat resistance, and its manufacturing method.SOLUTION: A blow-molded vessel is composed of at least two polymer blocks [A] with repeating units derived from aromatic vinyl compounds as main components, and at least one polymer block [B] with a repeating unit derived from a chain conjugated diene compound as a main component. When a weight fraction occupied in the whole of a block copolymer of the polymer block [A] is set as wA, and a weight fraction occupied in the whole of a block copolymer of the polymer block [B] is set as wB, (wA:wB) becomes 50:50 to 80:20 in a block copolymer [C]. The blow-molded vessel is composed of a block copolymer hydride in which 90% or more of a total unsaturated bond of the block copolymer [C] is hydrogenated [D]. The blow-molded vessel has a fuselage part and a neck part, and a ratio of a maximum value and a minimum value of a wall thickness at the same periphery of the fuselage part is not larger than 1.1. There is also provided a manufacturing method of the blow-molded vessel.

Description

  The present invention relates to a blow molded container comprising a specific block copolymer hydride and a method for producing the same, and more particularly, suitable for pharmaceutical containers or food containers, etc. The present invention relates to a small blow molded container and a method for manufacturing the same.

  Conventionally, glass containers have been used for pharmaceutical containers, food containers and the like, but plastic containers are being replaced from the viewpoint of weight reduction and easy disposal. Under such circumstances, it is reported that a specific block copolymer hydride container is excellent in transparency, heat resistance, chemical resistance, low elution, etc., and is therefore suitable for pharmaceutical containers and food containers. (Patent Documents 1 to 3).

  On the other hand, Patent Document 4 discloses a blow molded container obtained by blow molding an alicyclic structure-containing polymer resin at a specific draw ratio. This document also describes the draw ratio, cylinder temperature when molding a preform, and mold temperature during blow molding as molding conditions for providing a blow molded container having excellent solvent crack resistance. Has been.

International Publication WO00 / 077094 JP 2002-121244 A JP 2013-48560 A JP 2003-118718 A

The present inventors have selected a specific range for the content of the repeating unit derived from the aromatic vinyl compound of the block copolymer hydride and the repeating unit derived from the chain conjugated diene compound. It has been found that a specific block copolymer hydride [D] having a balanced heat-resistance property and excellent mechanical strength and solvent crack resistance properties can be obtained.
However, this block copolymer hydride [D] melt-molded product has a large difference in mechanical elastic modulus between the machine direction (MD direction) and the transverse direction (TD direction: Traverse Direction). In molding, there is a problem that when the preform is blow-molded, uneven thickness tends to occur within the same circumference corresponding to the TD direction of the body portion.
If the blow molded container has uneven thickness, repeated boiling sterilization or steam sterilization may cause deformation of the container or decrease in mechanical strength, which is not preferable.
The present invention has been made in view of such circumstances, and is suitable for pharmaceutical containers or food containers made of a specific block copolymer hydride [D], and has excellent heat resistance and blow molding with less uneven thickness. It aims at providing a container and its manufacturing method.

  As a result of intensive studies to achieve the above object, the inventors of the present invention heated a preform made of a specific block copolymer hydride [D] to a specific temperature range, in the vertical direction and the horizontal direction. It has been found that a blow-molded container with less uneven thickness can be obtained when blow-molding is performed such that the draw ratio is within a specific range, and the present invention has been completed.

Thus, according to the present invention, the following blow molded containers (1) to (3) and the method for producing the blow molded containers are provided.
(1) At least two polymer blocks [A] mainly composed of repeating units derived from an aromatic vinyl compound and at least one polymer block mainly composed of repeating units derived from a chain conjugated diene compound [ B], and the weight fraction of the whole polymer block [A] in the entire block copolymer is wA, and the weight fraction of the whole polymer block [B] in the whole block copolymer is wB. Occasionally, block copolymer hydrogen obtained by hydrogenating 90% or more of all unsaturated bonds of block copolymer [C] having a ratio of wA to wB (wA: wB) of 50:50 to 80:20 a blow-molded container comprising a compound [D] when having a body portion and a neck portion, the maximum value t _max thick in the same circumferential of the _body, the minimum value was t _min, t _max / in t _min is 1.1 or less Blow-molded container according to claim Rukoto.
(2) At least two polymer blocks [A] having as a main component a repeating unit derived from an aromatic vinyl compound and at least one polymer block having as a main component a repeating unit derived from a chain conjugated diene compound [ B], and the weight fraction of the whole polymer block [A] in the entire block copolymer is wA, and the weight fraction of the whole polymer block [B] in the whole block copolymer is wB. Occasionally, block copolymer hydrogen obtained by hydrogenating 90% or more of all unsaturated bonds of block copolymer [C] having a ratio of wA to wB (wA: wB) of 50:50 to 80:20 A blow molded container made of a compound [D], wherein a preform made of a block copolymer hydride [D] has a longitudinal draw ratio y of 1.01 to 1.3, For draw ratio y Method for producing a blow molded container lateral ratio of drawing ratio x of the maximum diameter portion of the body (x / y) is extended such that 1.1 to 2.
(3) A preform is molded using pellets of the block copolymer hydride [D] held at a temperature of 50 to 120 ° C. for 3 hours or more before blow molding, and the preform is continuously blow molded. (2) The method for producing a blow-molded container according to (2).

ADVANTAGE OF THE INVENTION According to this invention, the blow molding container which consists of specific block copolymer hydride [D] which is excellent in heat resistance and has few uneven thickness, and its manufacturing method are provided.
The blow molded container of the present invention is suitable as a pharmaceutical container or a food container.

The blow-molded container of the present invention has at least two polymer blocks [A] mainly comprising a repeating unit derived from an aromatic vinyl compound, and at least one repeating unit derived from a chain conjugated diene compound. The weight fraction of all polymer blocks [A] in the whole block copolymer is wA, and the weight fraction of all polymer blocks [B] in the whole block copolymer is comprised of two polymer blocks [B]. When the ratio is wB, 90% or more of the total unsaturated bonds of the block copolymer [C] in which the ratio of wA to wB (wA: wB) is 50:50 to 80:20 was hydrogenated. A blow-molded container made of a block copolymer hydride [D], which has a trunk portion and a neck portion, wherein the maximum value of the wall thickness within the same circumference of the trunk portion is t _max and the minimum value is t _min . _{when, t max} / _t and wherein the _in is 1.1 or less.

1. Block copolymer hydride [D]
The block copolymer hydride [D] used in the present invention is a polymer obtained by hydrogenating 90% or more of the total unsaturated bonds of the block copolymer [C] as a precursor.
The block copolymer [C] contains at least two polymer blocks [A] and at least one polymer block [B].

(Polymer block [A])
The polymer block [A] has a structural unit derived from an aromatic vinyl compound as a main component.
The content of the structural unit derived from the aromatic vinyl compound in the polymer block [A] is usually 90% by weight or more, preferably 95% by weight or more, more preferably 99% by weight or more.
When there are too few structural units derived from the aromatic vinyl compound in the polymer block [A], the heat resistance of the blow molded container according to the present invention may be lowered.

Moreover, polymer block [A] may contain components other than the structural unit derived from an aromatic vinyl compound. Examples of the component other than the structural unit derived from the aromatic vinyl compound include a structural unit derived from a chain conjugated diene and / or a structural unit derived from another vinyl compound. The content thereof is usually 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less, based on all structural units in the polymer block [A].
The plurality of polymer blocks [A] contained in the block copolymer hydride [D] may be the same as or different from each other as long as the above range is satisfied.

(Polymer block [B])
The polymer block [B] has a structural unit derived from a chain conjugated diene compound as a main component.
The content of the structural unit derived from the chain conjugated diene compound in the polymer block [B] is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more.
When the structural unit derived from the chain conjugated diene compound in the polymer block [B] is in the above range, flexibility is imparted to the blow molded container according to the present invention.

Moreover, polymer block [B] may contain components other than the structural unit derived from a chain conjugated diene compound. Examples of the component other than the structural unit derived from the chain conjugated diene compound include a structural unit derived from an aromatic vinyl compound and / or a structural unit derived from another vinyl compound. The content thereof is usually 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less, based on all structural units in the polymer block [B]. When the content of the structural unit derived from the aromatic vinyl compound in the polymer block [B] increases, the flexibility of the blow molded container according to the present invention at low temperatures may be reduced.
When the block copolymer hydride [D] has a plurality of polymer blocks [B], the polymer blocks [B] may be the same as or different from each other.

  As the aromatic vinyl compound, styrene; α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, Styrenes having an alkyl group having 1 to 6 carbon atoms as a substituent, such as 5-t-butyl-2-methylstyrene; halogen atoms as a substituent, such as 4-chlorostyrene, dichlorostyrene, 4-monofluorostyrene Styrenes having an alkoxy group having 1 to 6 carbon atoms as a substituent, such as 4-methoxystyrene; styrenes having an aryl group as a substituent, such as 4-phenylstyrene; 1-vinylnaphthalene, Vinyl naphthalenes such as 2-vinyl naphthalene; and the like. Among these, from the viewpoint of hygroscopicity, aromatic vinyl compounds that do not contain a polar group, such as styrene and styrenes having an alkyl group having 1 to 6 carbon atoms as a substituent, are preferable, because of industrial availability. Styrene is particularly preferred.

  Examples of the chain conjugated diene compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and the like, and does not contain a polar group from the viewpoint of hygroscopicity. A chain conjugated diene compound is preferred, and 1,3-butadiene and isoprene are particularly preferred from the viewpoint of industrial availability.

  Examples of other vinyl compounds include vinyl compounds, unsaturated cyclic acid anhydrides, and unsaturated imide compounds. These compounds may have a nitrile group, an alkoxycarbonyl group, a hydroxycarbonyl group, or a halogen atom as a substituent. Among these, from the viewpoint of hygroscopicity, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-eicosene, Does not contain polar groups such as chain olefins having 2 to 20 carbon atoms such as 4-methyl-1-pentene and 4,6-dimethyl-1-heptene; cyclic olefins having 5 to 20 carbon atoms such as vinylcyclohexane; Are preferred, chain olefins having 2 to 20 carbon atoms are more preferred, and ethylene and propylene are particularly preferred.

(Block copolymer [C])
The number of polymer blocks [A] in the block copolymer [C] is usually 5 or less, preferably 4 or less, more preferably 3 or less. When there are a plurality of polymer blocks [A] and / or polymer blocks [B], the weight average molecular weight of the polymer block having the maximum and minimum weight average molecular weight in the polymer block [A] is expressed as Mw (A ) When _max and Mw (A) _min are set, and the weight average molecular weight of the polymer block having the maximum and minimum weight average molecular weight in the polymer block [B] is Mw (B) _max and Mw (B) _min , respectively. , Mw (A) _max and Mw (A) _min ratio (Mw (A) _max / Mw (A) _min ) and Mw (B) _max and Mw (B) _min ratio (Mw (B) _max / Mw (B) _min ) is 4.0 or less, preferably 3.5 or less, and more preferably 3.0 or less.

  The form of the block of the block copolymer [C] may be a chain type block or a radial type block, but a chain type block is preferable because of excellent mechanical strength. The most preferable form of the block copolymer [C] is a triblock copolymer ([A]-[B]-[A]) in which the polymer block [A] is bonded to both ends of the polymer block [B]. The polymer block [B] is bonded to both ends of the polymer block [A], and the polymer block [A] is bonded to the other end of the both polymer blocks [B]. [A]-[B]-[A]-[B]-[A]).

  In the block copolymer [C], when the weight fraction of the whole polymer block [A] in the whole block copolymer is wA, the weight of the whole polymer block [B] in the whole block copolymer. When the fraction is wB, the ratio of wA to wB (wA: wB) is usually 50:50 to 80:20, preferably 55:45 to 75:25, more preferably 60:40 to 70:30. It is. When wA is too high, the heat resistance of the blow molded container according to the present invention is increased, but the flexibility is low, the mechanical strength and the solvent crack resistance may be insufficient, and when wA is too low. The heat resistance is lowered, and the blow molded container is easily shrunk by steam sterilization or boiling sterilization.

  The molecular weight of the block copolymer [C] is a polystyrene-reduced weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and usually 40,000 to 200. , Preferably 50,000 to 150,000, more preferably 60,000 to 100,000. Further, the molecular weight distribution (Mw / Mn) of the block copolymer [C] is preferably 3 or less, more preferably 2 or less, and particularly preferably 1.5 or less.

  As a method for producing the block copolymer [C], for example, a monomer mixture (a) containing an aromatic vinyl compound as a main component and a chain conjugated diene compound as a main component by a method such as living anion polymerization. A method of alternately polymerizing the monomer mixture (b) to be polymerized; a monomer mixture (a) containing an aromatic vinyl compound as a main component and a monomer mixture (b) containing a chain conjugated diene compound as a main component in order. Then, the method etc. of coupling the terminal of polymer block [B] with a coupling agent are mentioned.

(Block copolymer hydride [D])
The block copolymer hydride [D] is obtained by hydrogenating the carbon-carbon unsaturated bond of the main chain and the side chain of the block copolymer [C] and the carbon-carbon unsaturated bond of the aromatic ring. is there.
The hydrogenation rate is usually 90% or more, preferably 97% or more, more preferably 99% or more. The higher the hydrogenation rate, the better the weather resistance, heat resistance and transparency of the molded body. The hydrogenation rate of the block copolymer hydride [D] can be determined by measurement by ¹ H-NMR.

  There are no particular restrictions on the hydrogenation method or reaction mode of the unsaturated bond, and it may be carried out according to a known method, but a hydrogenation method that can increase the hydrogenation rate and has little polymer chain scission reaction is preferred. Examples of such a hydrogenation method include methods described in WO 2011/096389 pamphlet, WO 2012/043708 pamphlet and the like.

  After completion of the hydrogenation reaction, after removing the hydrogenation catalyst and / or polymerization catalyst from the reaction solution, the block copolymer hydride [D] can be recovered from the resulting solution. Although the form of the recovered block copolymer hydride [D] is not limited, it can be usually formed into a pellet shape and subjected to subsequent blow molding.

  The molecular weight of the block copolymer hydride [D] is a polystyrene-equivalent weight average molecular weight (Mw) measured by GPC using THF as a solvent, and is usually 40,000 to 200,000, preferably 50,000 to 150. , 000, more preferably 60,000 to 100,000. The molecular weight distribution (Mw / Mn) of the block copolymer hydride [D] is preferably 3 or less, more preferably 2 or less, and particularly preferably 1.5 or less. When Mw and Mw / Mn are within the above ranges, the heat resistance and mechanical strength of the molded blow molded container are good.

  When the block copolymer hydride [D] used in the present invention is blow-molded, another compounding agent may be contained. The compounding agent is not particularly limited, but is a stabilizer such as an antioxidant, a heat stabilizer, a light stabilizer, a weathering stabilizer, an ultraviolet absorber, a near infrared absorber, and the like; a resin modifier such as a lubricant and a plasticizer. Colorants such as dyes and pigments; antistatic agents and the like. These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the object of the present invention.

When blow molding the block copolymer hydride [D] to mold a container, it is effective to add an antioxidant in order to suppress oxidative degradation of the resin. Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. Examples of phenolic antioxidants include pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate and tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane. Examples of phosphorus antioxidants include triphenyl phosphite and diphenylisodecyl phosphite. Examples of the sulfur-based antioxidant include dilauryl thiodipropionate and dimyristyl thiodipropionate. These antioxidants can be used individually by 1 type, or can also be used in combination of 2 or more type. Among these, phenolic antioxidants, particularly alkyl-substituted phenolic antioxidants are preferred. These antioxidants can be used alone or in combination of two or more.
The blending amount of the antioxidant is appropriately selected within a range not impairing the object of the present invention, but is usually 0.01 to 1.0 part by weight with respect to 100 parts by weight of the block copolymer hydride [D], Preferably it is 0.02-0.5 weight part, More preferably, it is 0.05-0.3 weight part.

2. Blow Molded Container A blow molded container of the present invention is a blow molded container made of the above-described block copolymer hydride [D], and has a body part and a neck part, and has a wall thickness within the same circumference of the body part. When the maximum value is t _max and the minimum value is t _min , t _max / t _min is 1.1 or less, preferably 1.05 or less. By reducing the uneven thickness, it is possible to suppress deformation of the container even when the container is repeatedly subjected to steam sterilization or boiling sterilization.

The blow molded container of the present invention has a thickness of usually 0.5 to 3 mm, preferably 0.6 to 2.5 mm, more preferably 0.7 to 2.0 mm.
The shape of the container is not particularly limited as long as it has a body portion and a neck portion. Examples of the shape of the body portion include a cylindrical shape, a prismatic shape, a spherical shape, and the like, and a cylindrical shape is preferable from the viewpoint of mechanical strength and ease of use. Moreover, it does not restrict | limit especially about the shape of the bottom part of a container, The shape with a hollow toward the inside may be sufficient even if it is planar shape.
The blow molded container of the present invention is a neck and body that can be attached with a lid so that medicines, foods, etc. can be stored in a sealed manner, and can be treated such as steam sterilization while the medicines, foods, etc. are stored in a sealed state A shape having a portion is preferable. The neck portion preferably has a screw thread or an uneven portion that can be fitted to the lid so that the lid can be attached and sealed.

3. Blow Molded Container Manufacturing Method The blow molded container manufacturing method of the present invention is a blow molded container manufacturing method comprising the above block copolymer hydride [D], comprising the block copolymer hydride [D]. The preform has a longitudinal draw ratio y of 1.01 to 1.3, and a ratio (x / y) of the transverse draw ratio x in the maximum diameter portion of the body portion to the longitudinal draw ratio y is 1. .1 to 2 to be stretched.

The blow molded container of the present invention can be obtained by blow molding the specific block copolymer hydride [D].
The blow molding method includes a direct blow molding method and an injection blow molding method. In the present invention, an injection blow molding method that easily forms a thread on the neck of the blow molded container is preferably used.
Injection blow molding consists of (1) molding a preform that is a hollow body having an opening by injection molding, and (2) inserting the preform into a blow mold and heating and melting it from the opening. Blow molding is performed by blowing air inside. In the above method, it is usually preferable to use a columnar preform having a constant cross-sectional diameter.

  In the present invention, the stretching ratio (y) in the longitudinal direction is the ratio of the length of the neck (stretched portion) of the blow molded container to the length of the preform neck (stretched portion). The transverse draw ratio (x) is the ratio of the maximum transverse diameter of the blow molded container to the transverse diameter of the preform. The maximum diameter is the maximum diameter when the cross section of the blow molded container is circular, and the maximum equivalent diameter when the cross section of the blow molded container is polygonal or elliptical.

  The blow molded container of the present invention has a longitudinal draw ratio y of 1.01 to 1.3, preferably 1.03 to 1.25, more preferably 1.05 to 1.2. The ratio (x / y) of the draw ratio x in the transverse direction at the maximum diameter part of the body part to the draw ratio y is 1.1 to 2, preferably 1.15 to 1.9, more preferably 1.2 to 1. .8. By making the draw ratio y in the vertical direction and the ratio of the draw ratio in the vertical and horizontal directions (x / y) within the above ranges, the uneven thickness of the blow molded container can be reduced.

The molding conditions at the time of preform molding are as follows.
(I) Cylinder temperature is made into the range of 190-280 degreeC normally, Preferably it is 200-270 degreeC, More preferably, it is 210-260 degreeC. If the cylinder temperature is excessively low, the fluidity is deteriorated and the resulting container is distorted. If the cylinder temperature is excessively high, the container surface may be roughened due to thermal decomposition of the resin or the like. The diameter of the preform, the inner diameter of the hollow portion, and the length of the preform can be appropriately selected depending on the size of the intended container.

(Ii) a glass transition temperature of the high temperature side of the block copolymer hydrides [D] used in the case of a Tg _2, the preform is usually _{Tg 2 + 20 ℃ ~Tg 2 +} 50 ℃, preferably _Tg 2 + 25 ℃ ~ Tg ₂ + 45 ℃, more preferably heated to _{Tg 2 + 30 ℃ ~Tg 2 +} 40 ℃, stretched so that the above draw ratio.

(Iii) the temperature of the blow mold is usually _{Tg 2 -100 ℃ ~Tg 2 -10 ℃} , preferably _{Tg 2 -80 ℃ ~Tg 2 -20 ℃} , more preferably _Tg 2 -60 ℃ _~Tg 2 -30 ° C. When the preform molding conditions and the blow molding conditions are within the above ranges, the uneven thickness of the blow molded container can be reduced.

  In the present invention, it is preferable that the block copolymer hydride [D] pellets are held at a temperature of 50 to 120 ° C. for 3 hours or more before blow molding to be used for preform molding. Further, it is preferable that the molded preform is continuously subjected to blow molding without cooling. By heat-treating the block copolymer hydride [D] pellets under the above conditions, the amount of dissolved air contained in the pellets is reduced. As a result, the preform is prevented from being unevenly stretched during blow molding, and a blow molded container with less uneven thickness can be obtained. When the temperature and time of the heat treatment are within the above ranges, the amount of dissolved air removed is sufficient, and the uneven thickness of the blow-molded container is effectively reduced particularly in a region where the draw ratio is large.

  The blow molded container of the present invention is transparent and excellent in the visibility of contents, has characteristics such as low moisture absorption, low moisture permeability, and heat resistance, and can be boiled or steam sterilized. Therefore, it is suitable for pharmaceutical containers, food containers and the like. Specifically, it is suitable for a container for an aseptic preparation that is required to maintain a high degree of sterility and a container for a diagnostic agent such as a contrast medium. In addition, infusion containers and infusion kit containers; eye drops containers; pure water containers; sampling tubes for blood analysis; blood collection tubes; specimen containers; analysis containers such as UV test cells; Sterilized containers for medical instruments such as contact lenses; medical containers such as disposable syringes and prefilled syringes; laboratory instruments such as beakers, vials, ampoules, test tubes and flasks; housings for artificial organs; The blow molded container of the present invention is also suitable as a bottle for food storage containers, soft drinks, etc., but especially oils from sebum, saliva, etc. adhere to tableware, baby bottles, mugs, etc. It is also suitable as an easy food container.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to the following examples. Parts and% are based on weight unless otherwise specified.

Measurement and evaluation in this example are performed by the following methods.
(1) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)
The molecular weights of the block copolymer and the hydride of the block copolymer were measured at 38 ° C. as standard polystyrene conversion values by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent. As a measuring device, HLC8020GPC manufactured by Tosoh Corporation was used.
(2) Hydrogenation rate The hydrogenation rate of the main chain, side chain, and aromatic ring of the block copolymer hydride [D] was calculated by measuring a ¹ H-NMR spectrum.
(3) Glass transition temperature The block copolymer hydride was press-molded to produce a test piece having a length of 50 mm, a width of 10 mm, and a thickness of 1 mm. Using this test piece, from −100 ° C. to + 150 ° C. using a viscoelasticity measuring device (product name “ARES”, manufactured by T.A. Instruments Japan) based on JIS-K7244-2 method. The viscoelastic spectrum was measured at a temperature rising rate of 5 ° C./min. From the peak top temperature on the high temperature side of the loss factor tan δ, the glass transition temperature Tg ₂ on the high temperature side was determined.

(4) Thickness of Blow Molded Container The body of a blow molded container made of block copolymer hydride [D] is cut, and the thickness of 12 uniform parts within the same circumference is measured with an ultrasonic thickness gauge (KARL DUTSCH). The maximum value t _max and the minimum value t _min were measured, and t _max / t _min was calculated.
(5) Heat resistance of blow container A blow molded container made of a block copolymer hydride [D] is placed in a microwave disinfection device (DC microwave disinfection device, manufactured by Lek). About 60 ml of tap water is added into the microwave disinfector. Next, the microwave disinfector equipped with the measurement sample container is placed in a microwave oven (RE-50, rated voltage: 100 V, rated high frequency output: 500 W, oscillation frequency: 2450 MHz, manufactured by Sharp Corporation) and heated. The heat treatment time was 5 minutes. The same sterilization treatment was repeated 30 times, followed by drying in an oven at a temperature of 90 ° C. for 2 hours, and the appearance was visually observed. The case where no deformation of the shape was observed was evaluated as ◯ (good), and the case where the deformation was recognized was evaluated as x (bad). Ten blow molded containers were evaluated, and the number of good and bad was examined.
(6) Solvent crack resistance After coating tri-13-docosenoic acid glycerol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) on the entire surface of the body part of the blow molded container made of the block copolymer hydride [D], the above and It put in the same microwave sterilizer and heat-processed for 3 minutes using the same microwave oven as the above. The sample container was taken out and dried in an oven at a temperature of 90 ° C. for 2 hours, and then the appearance was visually observed. A case where whitening due to fine cracks was not observed was evaluated as ◯ (good), and a case where whitening was observed was evaluated as x (defective). Ten blow molded containers were evaluated, and the number of good and bad was examined.

[Reference Example 1] Production of block copolymer hydride [D1] In a reactor equipped with a stirrer and sufficiently purged with nitrogen inside, 550 parts of dehydrated cyclohexane, 30.0 parts of dehydrated styrene, and n-dibutyl ether 0.475 part was added. While stirring the whole volume at 60 ° C., 0.73 parts of n-butyllithium (15% cyclohexane solution) was added to initiate polymerization, and the whole volume was further stirred at 60 ° C. for 60 minutes. When the reaction solution was measured by gas chromatography, the polymerization conversion rate at this point was 99.5%.
Next, 40.0 parts of dehydrated isoprene was added to the reaction solution, and stirring was continued for 30 minutes. The polymerization conversion rate at this time was 99.5%. Thereafter, 30.0 parts of dehydrated styrene was further added and stirred for 60 minutes. The polymerization conversion rate at this point was almost 100%.
Here, 0.5 part of isopropyl alcohol was added to stop the reaction. The resulting block copolymer [C1] had a weight average molecular weight (Mw) of 57,700, a molecular weight distribution (Mw / Mn) of 1.04, and wA: wB = 60: 40.

  Next, the polymer solution was transferred to a pressure-resistant reactor equipped with a stirrer, and a diatomaceous earth supported nickel catalyst (product name “product name“ E22U ”, nickel supported amount 60%, manufactured by JGC Catalysts & Chemicals, Inc.) as a hydrogenation catalyst. ) 7.0 parts and 100 parts dehydrated cyclohexane were added and mixed. The inside of the reactor was replaced with hydrogen gas, and hydrogen was supplied while stirring the solution. A hydrogenation reaction was performed at a temperature of 190 ° C. and a pressure of 4.5 MPa for 6 hours. The weight average molecular weight (Mw) of the block copolymer hydride [D1] after the hydrogenation reaction was 61,100, and the molecular weight distribution (Mw / Mn) was 1.05.

After completion of the hydrogenation reaction, the reaction solution was filtered to remove the hydrogenation catalyst, and the filtrate was then subjected to pentaerythrityl tetrakis [3- (3,5-di-t-butyl-), which is a phenolic antioxidant. 4-hydroxyphenyl) propionate] (product name “Songnox 1010”, manufactured by Koyo Chemical Laboratory Co., Ltd.) 1.0 part of xylene solution in which 0.1 part was dissolved was added and dissolved.
Next, the above solution was filtered with a metal fiber filter (pore size 0.4 μm, manufactured by Nichidai) to remove minute solids, and then a cylindrical concentration dryer (product name “Contro”, manufactured by Hitachi, Ltd.) ), The solvent cyclohexane, xylene and other volatile components were removed from the solution at a temperature of 260 ° C. and a pressure of 0.001 MPa or less. The molten polymer is continuously filtered at a temperature of 260 ° C. with a polymer filter (manufactured by Fuji Filter) equipped with a stainless sintered filter having a pore diameter of 20 μm connected to a concentration dryer, and then the molten polymer is extruded into a strand form from a die. After cooling, 94 parts of pellets of block copolymer hydride [D1] were obtained by a pelletizer.

The pelletized block copolymer hydride [D1] had a weight average molecular weight (Mw) of 60,500, a molecular weight distribution (Mw / Mn) of 1.08, and a hydrogenation rate of almost 100%.
Molding of the block copolymer hydrides [D1] is colorless and transparent, glass transition temperature Tg ₂ of the high-temperature side was 137 ° C..

[Reference Example 2] Production of block copolymer hydride [D2] 50.0 parts of styrene, 30.0 parts of isoprene, and 20.0 parts of styrene were added in this order in three portions, and n-butyllithium ( Polymerization and reaction termination were carried out in the same manner as in Reference Example 1 except that the 15% cyclohexane solution was changed to 0.68 part.
The resulting block copolymer [C2] had a weight average molecular weight (Mw) of 62,800, a molecular weight distribution (Mw / Mn) of 1.04, and wA: wB = 70: 30.

Next, the polymer solution was hydrogenated in the same manner as in Reference Example 1. The weight average molecular weight (Mw) of the block copolymer hydride [D2] after the hydrogenation reaction was 66,500, and the molecular weight distribution (Mw / Mn) was 1.06.
After completion of the hydrogenation reaction, an antioxidant was added in the same manner as in Reference Example 1, followed by concentration and drying to obtain 96 parts of a block copolymer hydride [D2] pellet.

The pelletized block copolymer hydride [D2] had a weight average molecular weight (Mw) of 65,800, a molecular weight distribution (Mw / Mn) of 1.10, and a hydrogenation rate of almost 100%.
Molding of the block copolymer hydrides [D2] is colorless and transparent, glass transition temperature Tg ₂ of the high-temperature side was 138 ° C..

[Reference Example 3] Production of block copolymer hydride [D3] 30.0 parts of styrene, 45.0 parts of isoprene, and 25.0 parts of styrene were added in this order in three portions, and n-butyllithium ( Polymerization and reaction termination were carried out in the same manner as in Reference Example 1 except that the 15% cyclohexane solution was changed to 0.65 part.
The weight average molecular weight (Mw) of the obtained block copolymer [C3] was 64,300, the molecular weight distribution (Mw / Mn) was 1.04, and wA: wB = 55: 45.

Next, the polymer solution was hydrogenated in the same manner as in Reference Example 1. The weight average molecular weight (Mw) of the block copolymer hydride [D3] after the hydrogenation reaction was 68,100, and the molecular weight distribution (Mw / Mn) was 1.06.
After completion of the hydrogenation reaction, an antioxidant was added in the same manner as in Reference Example 1, and then concentrated and dried to obtain 93 parts of a block copolymer hydride [D3] pellet.

The pelletized block copolymer hydride [D3] had a weight average molecular weight (Mw) of 67,400, a molecular weight distribution (Mw / Mn) of 1.09, and a hydrogenation rate of almost 100%.
Molding of the block copolymer hydrides [D3] is colorless and transparent, glass transition temperature Tg ₂ of the high-temperature side was 136 ° C..

[Example 1]
The block copolymer hydride [D1] pellets obtained in Reference Example 1 were heat treated at 70 ° C. for 4 hours using a hot air dryer in which air was circulated, and then injected into a blow molding machine (ASB-12N / 10) (manufactured by Nissei ASB) with a cylinder temperature of 240 ° C. and a preform mold temperature of 100 ° C. A reform was formed. The preform has a neck that extends 30 mm from the opening, and a thread is formed on the neck.
Next, the preform is heated to 164 ° C. (Tg ₂ + 27 ° C.), the draw ratio y in the longitudinal direction (height direction) is 1.05, and the transverse direction (diameter direction) is stretched at the maximum diameter portion of the body portion. Using a blow mold with a magnification x of 1.71 (lateral stretch ratio / longitudinal stretch ratio = x / y = 1.63), air was blown into the preform under the condition of a blow mold temperature of 100 ° C. Blow molding was carried out while blowing to obtain a blow molded container 1 (for 300 ml) having a neck having an opening and a trunk having a height of 135 mm and a trunk having a diameter of 65 mm.

Using the obtained blow molded container 1, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated. The maximum thickness t _max at the maximum diameter portion of the body portion was 1.69 mm, the minimum value t _min was 1.63 mm, t _max / t _min was 1.04, and the uneven thickness was small.
In the appearance after 30 times of sterilization with a microwave oven, no deformation was observed and the heat resistance was good. In the evaluation of the solvent crack resistance, no whitening was observed. The results are shown in Table 1.

  On the other hand, from the weight change before and after the block copolymer hydride [D1] pellets were heated at 70 ° C. for 4 hours using a hot-air dryer in which air was circulated, the amount of dissolved air removed was equivalent to 190 ppm. did.

[Example 2]
A blow molded container 2 was molded in the same manner as in Example 1 except that the block copolymer hydride [D1] pellets were used without heat treatment before blow molding.
Using the obtained blow molded container 2, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Example 3]
Example 1 except that pellets of the block copolymer hydride [D2] obtained in Reference Example 2 were used, the cylinder temperature was changed to 250 ° C., and the preform heating temperature was changed to 169 ° C. (Tg ₂ + 31 ° C.). The blow molded container 3 was molded in the same manner as described above.
Using the obtained blow molded container 3, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Example 4]
Implementation was performed except that the block copolymer hydride [D2] pellets obtained in Reference Example 2 were used and the block copolymer hydride [D2] pellets were used without heat treatment before blow molding. A blow molded container 4 was molded in the same manner as in Example 3.
Using the obtained blow molded container 4, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Example 5]
Blow molding in the same manner as in Example 1 except that the block copolymer hydride [D3] pellet obtained in Reference Example 3 was used and the heating temperature of the preform was changed to 160 ° C. (Tg ₂ + 24 ° C.). Container 5 was molded.
Using the obtained blow molded container 5, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Example 6]
Implemented except that the block copolymer hydride [D3] pellets obtained in Reference Example 3 were used and the block copolymer hydride [D3] pellets were used without heat treatment prior to blow molding. A blow molded container 6 was formed in the same manner as in Example 5.
Using the obtained blow-molded container 6, the thickness of the blow-molded container, the heat resistance and the solvent crack resistance of the blow container were evaluated.

[Example 7]
The shape of the preform has a height of 117 mm, an opening diameter of 40 mm, a neck extending from the opening to 30 mm, a thread formed on the neck, and a cross section of the neck lower part having a diameter of 38 mm. A blow molded container 7 made of a block copolymer hydride [D1] having the same outer shape as in Example 1 was molded in the same manner as in Example 1 except that the longitudinal stretch ratio y and the lateral stretch ratio x were changed. The longitudinal draw ratio y was 1.21, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.42). It was.
Using the obtained blow molded container 7, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated. The maximum thickness t _max at the maximum diameter portion of the body portion was 1.71 mm, the minimum value t _min was 1.58 mm, t _max / t _min was 1.08, and the uneven thickness was small. In the appearance after 30 times of sterilization with a microwave oven, no deformation was observed and the heat resistance was good. In the evaluation of the solvent crack resistance, no whitening was observed.

[Example 8]
Blow molded container 8 having the same outer shape as that of Example 1 except that block copolymer hydride [D2] is used and the shape of the preform is the same as that of Example 7. Was molded. The longitudinal draw ratio y was 1.21, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.42). It was.
Using the obtained blow molded container 8, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Example 9]
A blow molded container 9 having the same outer shape as that of Example 1 except that the block copolymer hydride [D3] is used and the shape of the preform is the same as that of Example 7. Was molded. The longitudinal draw ratio y was 1.21, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.42). It was.
Using the obtained blow-molded container 9, the thickness of the blow-molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Comparative Example 1]
The shape of the preform was changed to a height of 107 mm, an opening diameter of 40 mm, a neck extending from the opening to 30 mm, a thread formed on the neck, and a cross section of the neck below the diameter of 38 mm, A blow molded container 10 made of a block copolymer hydride [D1] having the same outer shape as in Example 1 was molded in the same manner as in Example 1 except that the longitudinal stretch ratio y and the lateral stretch ratio x were changed. The longitudinal draw ratio y was 1.36, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.25). It was.
Using the obtained blow molded container 10, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated. The maximum thickness t _max at the maximum diameter portion of the body portion was 1.84 mm, the minimum value t _min was 1.52 mm, and t _max / t _min was 1.21, clearly showing uneven thickness. . In the appearance after sterilization with a microwave oven 30 times, the curvature on the thin side was reduced, deformation was observed, and the heat resistance was insufficient. In the evaluation of the solvent crack resistance, no whitening was observed.

[Comparative Example 2]
Blow-molded container 11 having the same outer shape as in Example 1 except that block copolymer hydride [D2] is used and the shape of the preform is the same as in Comparative Example 1. Was molded. The longitudinal draw ratio y was 1.36, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.25). It was.
Using the obtained blow molded container 11, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Comparative Example 3]
A blow molded container 12 having the same outer shape as that of Example 1 except that a block copolymer hydride [D3] is used and the shape of the preform is the same as that of Comparative Example 1. Was molded. The longitudinal draw ratio y was 1.36, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw ratio = x / y = 1.25). It was.
Using the obtained blow molded container 12, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Comparative Example 4]
Using the block copolymer hydride [D1] pellet obtained in Reference Example 1, the preform has a height of 130 mm, an opening diameter of 25 mm, and a neck extending from the opening to 20 mm. A screw thread is formed in the lower part of the neck, except that the diameter of the cross section of the lower part of the neck is 23 mm. Blow molding is performed in the same manner as in Example 1, and the height of the neck part having the opening part and the trunk part is 135 mm. A blow-molded container 13 (for 300 ml) having a diameter of the body part of 65 mm was obtained. The longitudinal draw ratio y was 1.05, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter part of the body part was 2.83 (lateral draw ratio / longitudinal draw ratio = x / y = 2.69). It was.
Using the obtained blow molded container 13, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated. The maximum thickness t _max at the maximum diameter portion of the body portion is 1.51 mm, the minimum value t _min is 1.17 mm, and t _max / t _min is 1.29. Clearly uneven thickness was recognized. . In the appearance after sterilization with a microwave oven 30 times, the curvature on the thin side was reduced, deformation was observed, and the heat resistance was insufficient. In the evaluation of the solvent crack resistance, no whitening was observed.

[Comparative Example 5]
A blow molded container 14 having the same outer shape as that of Comparative Example 4 except that the block copolymer hydride [D2] is used and the shape of the preform is the same as that of Comparative Example 4. Was molded. The longitudinal draw ratio y was 1.05, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter part of the body part was 2.83 (lateral draw ratio / longitudinal draw ratio = x / y = 2.69). It was.
Using the obtained blow molded container 14, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Comparative Example 6]
A blow molded container 15 having the same outer shape as that of Comparative Example 4 except that a block copolymer hydride [D3] is used and the shape of the preform is the same as that of Comparative Example 4. Was molded. The longitudinal draw ratio y was 1.05, and the draw ratio x in the transverse direction (diameter direction) at the maximum diameter part of the body part was 2.83 (lateral draw ratio / longitudinal draw ratio = x / y = 2.69). It was.
Using the obtained blow molded container 15, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated.

[Reference Example 4] Production of block copolymer hydride [D4] Styrene and isoprene were divided into three portions, and 20.0 parts of styrene, 60.0 parts of isoprene, and 20.0 parts of styrene were each in this order three times. Polymerization and reaction termination were performed in the same manner as in Reference Example 1 except that n-butyllithium (15% cyclohexane solution) was changed to 0.65 part. The obtained block copolymer [C4] had a weight average molecular weight (Mw) of 63,000, a molecular weight distribution (Mw / Mn) of 1.04, and wA: wB = 40: 60.

Next, the polymer solution was hydrogenated in the same manner as in Reference Example 1. The weight average molecular weight (Mw) of the block copolymer hydride [D4] after the hydrogenation reaction was 66,700, and the molecular weight distribution (Mw / Mn) was 1.05.
After completion of the hydrogenation reaction, an antioxidant was added in the same manner as in Reference Example 1, followed by concentration and drying to obtain 93 parts of pellets of block copolymer hydride [D4].

The pelletized block copolymer hydride [D4] had a weight average molecular weight (Mw) of 66,000, a molecular weight distribution (Mw / Mn) of 1.09, and a hydrogenation rate of almost 100%.
Molding of the block copolymer hydrides [D4] is colorless and transparent, glass transition temperature Tg ₂ of the high-temperature side was 127 ° C..

[Comparative Example 7]
The block copolymer hydride [D4] pellets obtained in Reference Example 4 were heat-treated at 50 ° C. for 4 hours using a hot air dryer in which air was circulated, and then a cylinder temperature of 230 ° C. and a preform mold. Except that the temperature was 80 ° C., a preform having a height of 130 mm, an opening diameter of 40 mm, and a neck section of 38 mm in diameter was formed in the same manner as in Example 1. Next, the preform was heated to 154 ° C. (Tg ₂ + 27 ° C.), the longitudinal draw ratio y was 1.05, and the transverse draw ratio x at the maximum diameter portion of the body portion was 1.71 (lateral draw ratio / longitudinal draw). Using a blow mold with a magnification = x / y = 1.63), blow molding was performed under the condition of a blow mold temperature of 90 ° C. to obtain a blow molded container 16 (for 300 ml) having the same shape as in Example 1. .

Using the obtained blow molded container 16, the thickness of the blow molded container, the heat resistance of the blow container, and the solvent crack resistance were evaluated. The maximum thickness t _max at the maximum diameter portion of the body portion was 1.70 mm, the minimum value t _min was 1.65 mm, t _max / t _min was 1.03, and the uneven thickness was small. In the appearance after 30 times of sterilization with a microwave oven, the container body was contracted to a diameter of about 50 mm, and the heat resistance was insufficient. In the evaluation of the solvent crack resistance, no whitening was observed.

About the blow molding containers 1 to 16 of Examples 1 to 9 and Comparative Examples 1 to 7, the type of the block copolymer hydride [D] used, Tg ₂ , the temperature and time of the heat treatment of the pellets, and the blow molding conditions ( Table 1 shows the cylinder temperature, preform mold temperature, preform heating temperature, blow mold temperature, and draw ratio).
Moreover, the thickness of the trunk | drum part about the blow molding containers 1-16 of Examples 1-9 and Comparative Examples 1-7, a heat resistance test, and the result of a solvent crack resistance test are put together in Table 2, and are shown.
In Table 2, 1) indicates that the curvature of the thin portion was reduced or deformed, and 2) indicates that the body portion of the container was contracted or deformed.

The following can be seen from the results of this example and the comparative example.
Blow molding containers 1 to 9 made of a specific block copolymer hydride [D] within the scope of the present invention have a longitudinal stretch ratio y and a lateral stretch ratio / longitudinal stretch ratio = x / y within a specific range. The thickness is small, it is not deformed even by repeated steam sterilization treatment using a microwave oven, and cracks do not occur even when oils and fats are attached, showing good heat resistance and good solvent crack resistance (implementation) Examples 1-9).
Further, before the blow molding, the block copolymer hydride [D] pellets are heat-treated to reduce the amount of dissolved air, thereby obtaining a blow molded container having a smaller uneven thickness (Examples 1 and 3). 5).
On the other hand, even when the specific block copolymer hydride [D] is used, if the longitudinal draw ratio y and / or the transverse draw ratio x exceeds the range of the present invention, the body part of the blow molded container The uneven thickness within the same circumference becomes large, and the repeated steam sterilization process using a microwave oven causes the thin side to shrink and cause deformation, resulting in poor heat resistance (Comparative Examples 1 to 6).
When the weight fraction wA occupying the entire block copolymer of the polymer block [A] having a repeating unit derived from an aromatic vinyl compound as a main component is lower than the range of the present invention, a blow molded container having a small uneven thickness is used. Even if it exists, it is deformed by repeated steam sterilization using a microwave oven, and the heat resistance is insufficient (Comparative Example 7).

  The blow molded container with a small uneven thickness, which is made of the specific block copolymer hydride [D] of the present invention, has heat resistance against steam sterilization or boiling sterilization, and is useful as a pharmaceutical container or a food container. . Moreover, according to the manufacturing method of this invention, said blow molded container can be manufactured and is industrially useful.

Claims (3)

At least two polymer blocks [A] mainly composed of repeating units derived from an aromatic vinyl compound, and at least one polymer block [B] mainly composed of repeating units derived from a chain conjugated diene compound. Consists of
When the weight fraction of the entire polymer block [A] in the entire block copolymer is wA, and the weight fraction of the entire polymer block [B] in the entire block copolymer is wB, wA and wB Block copolymer [C] having a ratio (wA: wB) of 50:50 to 80:20, comprising a hydride of block copolymer [D] obtained by hydrogenating 90% or more of all unsaturated bonds. A blow molded container,
Having a torso and neck,
Maximum value _{t max} thick in the same circumferential of the body, when the minimum value was _{t min,} a blow molded container, characterized in that t max _{/ t min} is 1.1 or less. At least two polymer blocks [A] mainly composed of repeating units derived from an aromatic vinyl compound, and at least one polymer block [B] mainly composed of repeating units derived from a chain conjugated diene compound. Consists of
When the weight fraction of the entire polymer block [A] in the entire block copolymer is wA, and the weight fraction of the entire polymer block [B] in the entire block copolymer is wB, wA and wB Block copolymer [C] having a ratio (wA: wB) of 50:50 to 80:20, comprising a hydride of block copolymer [D] obtained by hydrogenating 90% or more of all unsaturated bonds. A method of manufacturing a blow molded container,
The preform made of the block copolymer hydride [D] is stretched in the transverse direction at the maximum diameter portion of the body portion with respect to the stretching ratio y in the longitudinal direction of 1.01 to 1.3 and the stretching ratio y in the longitudinal direction. A method for producing a blow-molded container that is stretched so that the ratio (x / y) of the magnification x is 1.1 to 2.   A preform is molded using pellets of block copolymer hydride [D] held at a temperature of 50 to 120 ° C. for 3 hours or more before blow molding, and the preform is continuously blow molded. The method for producing a blow molded container according to claim 2.