JP2003053915A - Blow molded container for liquid milk product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blow molded container having a multilayered structure for a liquid milk product excellent from an aspect of a smell and taste and excellent in surface gloss, drop strength and handleability, and useful for a milk product such as milk, a milky beverage, yogurt or the like. SOLUTION: The blow molded container for the liquid milk product comprises a multilayered structure of two or more layers with a polypropylene resin composition containing a phenolic oxidation inhibitor and/or a hindered amine stabilizer (a) and a neutralizing agent (b) in an outermost layer comprising, and a polyethylenic resin in an innermost layer. A 6-10C volatile hydrocarbon is not more than 300 ppm, and a 11-30C origomer component is not more than 600 ppm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a blow molding container for liquid dairy products such as milk, and particularly to a blow molding container for liquid dairy products which is excellent in odor and taste and has excellent surface gloss, drop strength and handleability. Regarding the container.

[0002]

2. Description of the Related Art Materials for blow containers for dairy products such as dairy drinks and yogurt are made in accordance with the Ministry of Health and Welfare Ordinance No. 52 of 1952 (packaging container of rigid resin such as milk, standard of raw materials),
Standardized and currently accepted raw materials are limited to polyethylene, ethylene and 1-alkene copolymers, etc., and high density polyethylene and low density polyethylene of high pressure radical polymerization method are partially used. ing. However, blow containers molded with high-density polyethylene tend to be rough on the outer surface during blow molding and have poor gloss, so that dairy products such as milk tend to be disliked by consumers who are accustomed to high-gloss glass bottle containers. .

On the other hand, in the case of high density radical polymerization low density polyethylene, although it is excellent in glossiness and transparency, it is too low in rigidity so that the surface is not easily scratched and the buckling strength is lowered, so that it is covered. If the thickness of the product is increased, not only the transparency is deteriorated but also the product cost is increased, which is not practical value. Among polypropylene resins, a polypropylene random copolymer obtained by copolymerizing propylene and an α-olefin other than propylene is excellent in gloss and transparency, but is inferior in low-temperature drop strength and is extremely poor in blow moldability and is 1 L or more. It was difficult to mold a large container, and it was also difficult to mold a container having a handle structure.

Further, in the case of a polypropylene resin, when it is melted and pelletized from a polymerized powder, and when it is thermoformed by a blow molding machine, the odor is increased due to an increase in a low molecular weight component due to heat deterioration as compared with a polyethylene resin. Getting worse.
In order to prevent this thermal deterioration, it is sufficient to add an antioxidant, a neutralizing agent, etc., but depending on the type and amount of the additive, the preventive effect may be insufficient, or the additive itself may have a bad taste. There was a problem that made it worse. Other substances that cause odor include unreacted monomers used in the polymerization process, residual solvent,
Additives and their decomposed substances, low molecular weight oligomers generated in the polymerization process, impurities brought in from the outside in the polymerization process or molding process, and the like are considered. ,

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of glossiness in high-density polyethylene, the rigidity of high-pressure radical polymerization low-density polyethylene, and the problems of polypropylene drop strength and moldability. Another object of the present invention is to provide a blow-molded container for liquid dairy products which is particularly excellent in odor and taste.

[0006]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventors have identified a specific polypropylene resin composition for the outermost layer and a specific polyethylene resin for the innermost layer. With a multi-layered structure, it has excellent odor and taste, surface gloss, drop strength, volume reduction,
The inventors have found that a blow-molded container for liquid dairy products that is excellent in handleability can be obtained, and completed the present invention.

That is, the present invention is as follows. 1. A multilayer structure of two or more layers using a polypropylene resin composition containing (a) a phenolic antioxidant and / or a hindered amine stabilizer and (b) a neutralizing agent as an outermost layer and a polyethylene resin as an innermost layer. Consisting of 6 carbons
Volatile hydrocarbon of 10 is 300ppm or less, carbon number 11
The blow molding container for liquid dairy products, wherein the oligomer component of -30 is 600 ppm or less. 2. The blow molding container for liquid dairy products according to claim 1, wherein the polypropylene-based resin composition further contains (C) a phosphorus-based antioxidant. 3. The blow molding container for liquid dairy products according to claim 1 or 2, wherein the neutralizing agent is at least one selected from fatty acid metal salts, hydrotalcite, and metal hydroxide salts. 4. Polypropylene resin, melt flow rate 3g
It is a polypropylene random copolymer of / 10 minutes or more, The blow molding container for liquid dairy products of any one of Claims 1-3. 5. An intermediate layer made of a mixture of a polypropylene random copolymer and a polyethylene-based resin is provided between the outermost layer and the innermost layer.
A blow-molded container for liquid dairy products according to item. 6. The blow molding container for liquid dairy products according to any one of claims 1 to 5, wherein the outermost layer of the polypropylene-based resin composition has a thickness of 0.5 to 50% with respect to the entire layer. 7. The capacity is 1000 cc or more, and a handle structure is provided from the body to the mouth of the container.
A blow-molded container for liquid dairy products according to any one of claims 1 to 6.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION [I] Polypropylene Resin Composition The polypropylene resin composition in the present invention comprises a polypropylene resin and an additive component.

1. Polypropylene-based resin The polypropylene-based resin used in the present invention includes a homopolymer of propylene and a polypropylene random copolymer of propylene and α-olefin, and the α-olefin includes ethylene and butene having 2 to 8 carbon atoms. -1,
Pentene-1, hexene-1,4-methyl-pentene-
1, octene-1 and the like. The propylene / ethylene random copolymer is most preferably used. Two or more kinds of α-olefins other than propylene can be used in combination. For example, a propylene / ethylene / hexene terpolymer, a propylene / ethylene / octene terpolymer, and the like can also be used. The amount of α-olefin copolymerized in polypropylene is preferably 1% by weight or more. If the amount of α-olefin copolymerized is small, the drop strength and transparency of the blow container are lowered. Further, if the amount of the α-olefin copolymerized is too large, the rigidity decreases.

The polypropylene-based resin can be produced by a process such as slurry, bulk, gas phase method, etc., using a Chiguenatta type catalyst or a metallocene catalyst. JIS-K7210 of this polypropylene resin
The melt flow rate (MFR) measured by (230 ° C., 2.16 kg load) is 3 g / 10 minutes or more, preferably 5 g / 10 minutes or more, and particularly preferably 10 g / 10 minutes or more. The MFR is measured in the state of the polypropylene resin composition after the polypropylene resin is mixed with the additive. If the MFR of the polypropylene resin composition is less than the above, the surface of the molten resin (molten parison) extruded in a cylindrical shape during blow molding becomes rough, and the transparency becomes worse than the gloss. Further, if this MFR is too high, the drop strength will decrease.

2. Additive component The additive component added to the polypropylene resin composition of the present invention includes (a) a phenolic antioxidant and / or a hindered amine stabilizer, (b) a neutralizing agent, and, if necessary, ( c) A phosphorus-based antioxidant. The polypropylene resin composition comprises (a) a phenolic antioxidant and / or
Or, if it does not contain a hindered amine stabilizer, burns may occur during molding of the container for dairy products, and problems may occur, and the odor may transfer to the dairy products.
It becomes a problem. Further, when the neutralizing agent is not contained, there is a concern that chlorine, which remains as an impurity, may affect the propylene polymerization catalyst and process. The neutralizing agent also functions as a dispersant and improves the dispersibility of the pigment and the like. Furthermore, the phosphorus-based antioxidant is effective not only for preventing deterioration of the resin composition at the time of molding and processing, for suppressing burns and suppressing odor generation, but also for suppressing discoloration. That is,
The dairy product container is often colored with a white pigment, but it may turn yellow due to aging or the like. On the other hand, phosphorus-based antioxidants are effective because they have the effect of suppressing discoloration. (C) A lactone antioxidant and vitamin E can be used in place of the phosphorus antioxidant. Hereinafter, specific examples of each additive that can be used in the present invention and their preferable mixing ratios are shown.

(A-1) Phenolic Antioxidant Specific examples of the phenolic antioxidant which can be used in the present invention include tris- (3,5-di-t-butyl-).
4-hydroxybenzyl) -isocyanurate, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane, octadecyl-3- (3,3
5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], 1,3,5-trimethyl-2,4
6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 3,9-bis [2- [3- (3-
t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,
Examples include 4,8,10-tetraoxaspiro [5,5] undecane, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid and the like. Further, these phenolic antioxidants may be used alone or in combination of two or more kinds.

The blending amount of this phenolic antioxidant is
0.01 to 100 parts by weight of polypropylene resin
It is 0.5 part by weight, preferably 0.02 to 0.3 part by weight. If it is less than this amount, the heat aging resistance of the product is not sufficient. On the other hand, if it is excessive, not only is it uneconomical, but also discoloration and bleeding problems occur, which is not preferable.

(A-2) Hindered amine light stabilizer As specific examples of the hindered amine light stabilizer which can be used in the present invention, dimethyl succinate and 1- (2
-Hydroxyethyl) -4-hydroxy-2,2,6,
Polycondensation product with 6-tetramethylpiperidine, poly [[6
-(1,1,3,3-tetramethylbutyl) amino-
1,3,5-triazine-2,4-diyl] [(2,
2,6,6-Tetramethyl-4-piperidyl) imino]
Hexamethylene [(2,2,6,6-tetramethyl-4
-Piperidyl) imino]], 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid bis (1,2,2,6,6-pentamethyl-4-
Piperidyl) ester, tetrakis (2,2,6,6-
Tetramethyl-4-piperidyl) -1,2,3,4-butane tetracarboxylate, bis (2,2,6,6-
Tetramethyl-4-piperidyl) sebacate, N, N '
A polycondensate of -bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 1,2-dibromoethane, poly [(N, N'-bis (2,2,6,2
6-Tetramethyl-4-piperidyl) hexamethylenediamine)-(4-morpholino-1,3,5-triazine-2,6-diyl)], 1,1 ′-(1,2-ethanediyl) -bis ( 3,3,5,5-tetramethylpiperazinone), tris (2,2,6,6-tetramethyl-4-)
Piperidyl) -dodecyl-1,2,3,4-butanetetracarboxylate, tris (1,2,2,6,6-petanemethyl-4-piperidyl) -dodecyl-1,2,
3,4-butanetetracarboxylate, bis (1,
2,2,6,6-Petanemethyl-4-piperidyl) sebacate and the like can be mentioned.

These hindered amine antioxidants may be used alone or in combination of two or more. Particularly, those having a molecular weight of 500 or more are preferable in terms of compatibility and excellent effect. Among these, the most suitable compound is poly [[6- (1-poly (1)-(2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine] , 1,3,3-Tetramethylbutyl) amino-1,3,5-triazine-2,4-
Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-
Tetramethyl-4-piperidyl) imino]], poly [(N, N′-bis (2,2,6,6-tetramethyl-
4-piperidyl) hexamethylenediamine)-(4-morpholino-1,3,5-triazine-2,6-diyl)] and the like.

The amount of the hindered amine component blended is 0.01 to 0.1 per 100 parts by weight of the polypropylene resin.
5 parts by weight, preferably 0.02-0.3 parts by weight.
If it is less than this amount, the heat aging resistance of the product is not sufficient, while
If the amount is excessive, not only is it uneconomical, but also discoloration and bleeding problems occur, which is not preferable.

(B) Neutralizing agent Examples of the neutralizing agent that can be used in the present invention include fatty acid metal salts, hydrotalcites, metal hydroxide salts and the like. Even if they are used alone, two or more kinds are used in combination. You may use it. The content of the neutralizing agent is 0.01 to 0.5 parts by weight, preferably 0.0 to 100 parts by weight of the polypropylene resin.
2 to 0.2 parts by weight. If it is less than this amount, the effect of preventing corrosion of the mold, molding machine, etc. is not sufficient, while if it is excessive, not only is it uneconomical, but problems such as bleeding occur. Specific examples of the fatty acid metal salt, hydrotalcite and metal hydroxide salt are as follows.

(B-1) Fatty Acid Metal Salt The fatty acid metal salt that can be used in the present invention includes calcium stearate, magnesium stearate, zinc stearate, aluminum stearate, lithium stearate, sodium stearate and benzene. Calcium acid, magnesium behenate, zinc behenate, aluminum behenate, lithium behenate, similar metal laurate, metal montanate, metal melicinate, metal serotate, lignocerine Examples thereof include acid metal salts and hydroxystearic acid metal salts. Among these, metal soaps such as lithium stearate, magnesium stearate, zinc stearate, calcium stearate, aluminum stearate, magnesium behenate, zinc behenate, and calcium behenate are particularly preferred because of their performance and availability. preferable. These metal salts can be produced by a synthetic method in which a carboxylic acid compound and a metal hydroxide are reacted, followed by washing with water, dehydration, and drying (metathesis method), or a method of directly reacting without using water (direct method). it can.

(B-2) Hydrotalcites The hydrotalcites that can be used in the present invention do not contain a water-containing basic carbonate such as magnesium, calcium, zinc, aluminum or bismuth or crystal water. , Natural products and synthetic products. Examples of natural products include those having a structure of Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O. In addition, as a synthetic product, Mg _0.7 Al _0.3
(OH) ₂ (CO ₃ ) _0.15・ 0.54H ₂ O, Mg _4.5 Al
_{2 (OH) 1 3 CO 3} · 3.5H 2 O, Mg 4.2 Al 2 (O
_{H) 12.4 CO 3, Zn 6} Al 2 (OH) 16 CO 3 · 4H
₂ O, Ca ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, Mg ₁₄ B
_{i 2 (OH) 2 9.6 ·} 4.2H 2 O , and the like.

(B-3) Metal Hydroxide Salt Examples of the metal hydroxide salt that can be used in the present invention include magnesium hydroxide, aluminum hydroxide and lithium aluminum complex hydroxide salt.

(B-4) Other Neutralizing Agent Instead of the fatty acid metal salt, calcium stearoyl lactate, sodium stearoyl lactate or magnesium stearoyl lactate can be used.

(C) Phosphorus-Based Antioxidant In the present invention, the phosphorus-based antioxidant that can be used, if necessary, is a phosphorus-type antioxidant generally used as an oxidation stabilizer for resin compositions, particularly Can be listed without limitation. Specifically, tris (mixed, mono and dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 4,4-butylidene bis (3-methyl-6-t-butyl) Phenyl-di-tridecyl) phosphate, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5)
-T-butylphenyl) butane, bis (2,4-di-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-butylphenyl) -4
-4'-biphenylene phosphonite pentaerythritol-di-phosphite, bis (2,6-di-butyl-4-methylphenyl) pentaerythritol-di-
Phosphite, 2,2'-ethylidene bis (4,6-
Di-t-butylphenyl) fluorophosphite, methylenebis (4,6-di-t-butylphenyl) -2-
Examples thereof include ethylhexyl-phosphite.

These may be used alone or in combination of two or more. Among these, more preferred compounds include tris (2,4-di-t-butylphenyl) phosphite and tetrakis (2,4-di-butylphenyl).
-4-4'-biphenylene phosphonite pentaerythritol-di-phosphite, bis (2,6-di-
Butyl-4-methylphenyl) pentaerythritol-
Di-phosphite, 2,2'-ethylidene bis (4,
6-di-t-butylphenyl) fluorophosphite and methylenebis (4,6-di-t-butylphenyl)
A compound of 2-ethylhexyl-phosphite is a preferred example. The amount of the phosphorus-based antioxidant compounded is 0.01 to 0.5 part by weight, preferably 0.02 to 0.3 part by weight, per 100 parts by weight of the polypropylene resin. If it is less than this amount, the heat aging resistance of the product is not sufficient. On the other hand, if it is excessive, not only is it uneconomical, but also discoloration and bleeding problems occur, which is not preferable.

[II] Polyethylene resin 1. Types of polyethylene-based resin Examples of the polyethylene-based resin used in the present invention include ethylene homopolymers and copolymers of ethylene and α-olefins, and the α-olefins include propylene, butene-1, and pentene-1. , Hexene-1,4-methyl-
Pentene-1, octene-1, etc. are mentioned. As concrete polyethylene, high density polyethylene (HDP
E), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LL)
DPE), ultra low density polyethylene (V-LDPE), etc.

Among these, ionic polymerization catalysts such as Ziegler catalysts, Phillips type catalysts and metallocene catalysts are used to intentionally have a high molecular weight component and a low molecular weight component by a slurry method, a solution method, a gas phase method or the like. The designed homopolymer having a wide molecular weight distribution, or high density polyethylene or medium density polyethylene which is a copolymer of ethylene and α-olefin is preferable because of excellent moldability and rigidity.

As this polyethylene resin, JIS
Melt flow rate (MFR) measured by -K7210 (190 ° C, 2.16 kg load) is 0.1 to 10 g.
/ 10 minutes is preferable, and more preferably, a physical property value within a range of 1 to 5 g / 10 minutes is shown. If the MFR is too small, extrusion becomes difficult during molding, and the outer surface of the resin causes rough skin. On the other hand, if the MFR is too large, the resin sags at the time of molding to reduce drawdown, making molding difficult, and molding with a large container capacity becomes impossible.

As for the molecular weight distribution, gel permeation chromatography (GPC: Gel Permeation Chromatog
The ratio (Q value) of the weight average molecular weight to the number average molecular weight measured by raphy) is preferably 6 or more, more preferably 8 or more. The smaller the Q value, the worse the drawdown property in terms of MFR, and the smaller the swell (swell) of the molten parison, which makes it difficult to form a container having a handle structure. The density of this polyethylene resin is 0.86 to a value measured by JIS-K6992.
0.97 g / cm ³ is preferred. When the density is high, impact strength and transparency are lowered, and when the density is low, rigidity is lowered. Therefore, it is desirable to select it according to the intended container performance.

2. Additive Components Various additives and pigments may be added to the polyethylene-based resin of the present invention, but in the present invention, since this polyethylene-based resin is used for the inner layer in contact with a liquid dairy product, odor,
From the viewpoint of taste, it is preferable that the additive is not added as much as possible, and it is preferable that the phenol-based antioxidant, the hindered amine-based stabilizer, and the phosphorus-based antioxidant are not included. However, a phenol-based antioxidant, a hindered amine-based stabilizer, and a phosphorus-based antioxidant may be used as long as the amount thereof is a trace amount mixed in the manufacturing process. In this case, the trace amount is 0.02% by weight of each antioxidant with respect to the polyethylene resin.
It is about the following. Further, the neutralizing agent such as fatty acid metal salt is 0.
If it is 25% by weight or less and the glycerin fatty acid ester as an antistatic agent is 0.03% by weight or less, there is no particular adverse effect on odor and taste.

[III] Blow container for liquid dairy products 1. Volatile hydrocarbons and oligomer components The lower volatile hydrocarbons contained in the liquid dairy blow container are unreacted monomers in the polyolefin and have a degree of polymerization of 2 to
Various additives such as about 5 oligomers and antioxidants,
Residues of various polymerization solvents, lubricating oils of various polymerization equipment, impurities mixed from outside the system during polymerization reaction and heat processing, and decomposition products and oxides of these various components (carboxylic acids,
Aldehydes) and the like. The oligomer component contained in the liquid dairy blow container may be a polypropylene type oligomer having a carbon number of multiples of 3 or a polyethylene type oligomer having a carbon number of multiples of 2.
The oligomer component is originally generated from a polymer having a low degree of polymerization or a polymer decomposed from a polymer having a high degree of polymerization, and these oxides (carboxylic acids, aldehydes) are also considered to affect the flavor. The liquid dairy product blow container has a volatile hydrocarbon content of 6 to 10 carbon atoms of 3 or less.
00 ppm or less, preferably 150 ppm or less, more preferably 100 ppm or less, further preferably 50 pp
m or less, particularly preferably 20 ppm or less, more preferably about 0.01 ppm, and the content of the oligomer component having 12 to 30 carbon atoms is 600 ppm or less, preferably 3
00ppm or less, more preferably 250ppm or less, further preferably 60ppm or less, particularly preferably 20p
pm or less, more preferably about 0.01 ppm.
If the volatile hydrocarbon having 6 to 10 carbon atoms contained in the resin of the container exceeds 300 ppm, it is not preferable because odor is easily generated when heat-sterilizing the dairy product in the container or during storage. Further, if the oligomer having 12 to 30 carbon atoms contained in the resin of the container exceeds 600 ppm, the taste may change when heat sterilizing the dairy product in the container or during storage, which is not preferable.

As a method of reducing the volatile hydrocarbons and oligomer components of the present invention, in the case of polypropylene resin, the additives (a) and (b) and, if necessary, the additive (c) are added to the polypropylene resin. And then post-treatment has 6 to 1 carbon atoms
0 volatile hydrocarbon and a method of reducing the content of an oligomer having 12 to 30 carbon atoms to a predetermined amount or less, volatile hydrocarbon having 6 to 10 carbon atoms and 12 to 3 carbon atoms in a polypropylene resin
The method of adding the additive of (a), (b) and (c) if necessary after the oligomer content of 0 is reduced to a predetermined amount or less by post-treatment, and the polypropylene resin is a volatile hydrocarbon having 6 to 10 carbon atoms. And (a), (b) and, if necessary, the additive of (c) is added after polymerizing the content of the oligomer having 12 to 30 carbon atoms to a predetermined amount or less. The present invention may use either method.

On the other hand, in the case of a polyethylene resin, the addition of an antioxidant or the like is preferable as compared with a polypropylene resin because the generation of a low molecular weight component due to molecular cleavage by heat is less than that of a polypropylene resin. It is also possible to add an agent, and a method of reducing the content of volatile hydrocarbons having 6 to 10 carbon atoms and oligomers having 12 to 30 carbon atoms to a predetermined amount or less by post-treatment, and volatile polyethylene resin having 6 to 10 carbon atoms. There is a method of polymerizing the contents of the hydrocarbon and the oligomer having 12 to 30 carbon atoms to be a predetermined amount or less, and then adding an additive as necessary. The present invention may use either method.

As a method for reducing the volatile hydrocarbons and oligomer components of polypropylene-based resins and polyethylene-based resins, 1) remove the oligomer content by slurry polymerization and enhance drying with a dryer to enhance solvent and volatile hydrocarbons. 2) Method for reducing the residence time of polymerization to suppress the formation of oligomer components, and enhancing drying with a dryer to reduce volatile hydrocarbons 3) Providing a washing step with a low boiling point solvent such as propylene To reduce oligomers and enhance drying with a dryer to reduce volatile hydrocarbons. In addition, as a method for enhancing the drying using the above resin powder, the drying treatment temperature is 60 to 10
The temperature is 0 ° C., the drying time is 1 to 4 hours, and the deodorizing treatment may be combined with a treatment method of warm air drying of the pellets. Here, the amount of volatile hydrocarbons having 6 to 10 carbon atoms is a value obtained by measuring a gas obtained by thermally decomposing a sample with a gas chromatograph, and the amount of oligomer components having 12 to 30 carbon atoms. Is the amount obtained by measurement by gas chromatography / mass spectrometry.

2. Multilayer Structure The blow molding container for liquid dairy products of the present invention has a multilayer structure of two or more layers using a polypropylene resin composition as the outermost layer and a polyethylene resin as the innermost layer. Examples of the method for molding this blow-molded container having a multilayer structure include a direct blow molding method having a plurality of extruders and a multilayer die, a rotary blow molding method, and the like. As the actual blow molding conditions, a molding temperature is 160 to 280 ° C. and a blowing pressure is 2
Conditions of 10 to 10 kg / cm ² and a blow ratio of 1.2 to 5.0 are preferable.

The layer structure may be any structure as long as it uses a polypropylene resin composition as the outermost layer and a polyethylene resin as the innermost layer, and may have a multilayer structure of three or more kinds. The preferred multilayer structure in the present invention is a multilayer structure of three or more types including an intermediate layer in which a polypropylene resin and a polyethylene resin are mixed between the outermost polypropylene resin composition and the innermost polyethylene resin. The layer obtained by mixing the polypropylene-based resin and the polyethylene-based resin has an effect of welding the polypropylene-based resin and the polyethylene-based resin, and plays a role as a kind of adhesive layer.

As a method for mixing the polypropylene resin and the polyethylene resin, the ratio of the polyethylene resin to the polypropylene resin is about 5 to 95% by weight, preferably 10 to 90% by weight. Examples of the mixing method include a dry blending method in which polypropylene-based resin and polyethylene-based resin pellets are directly mixed and supplied to a blow molding machine, or a method in which the polypropylene-based resin and the polyethylene-based resin are melt-mixed in advance with a melt-kneader. Can be used. In addition, crushed burrs generated during the production of the blow-molded product can be crushed and used as a layer in which polypropylene-based resin and polyethylene-based resin are mixed, which is more industrially advantageous than cost. large. In addition, when the polypropylene resin and the polyethylene resin are dry-blended or melt-blended, the additives (a) and (b) described above may be added.

Examples of the mixer or kneader used for the above mixing include Henschel mixer, super mixer, V blender, tumbler mixer, ribbon blender, Banbury mixer, kneader blender,
Brabender plastograph, roll, single screw extrusion granulator, twin screw extrusion granulator and the like can be mentioned. The kneading temperature is generally 160 to 300 ° C.

The total thickness of the polyethylene resin layer used in the blow molding container for liquid dairy products of the present invention (in the case of a two-layer structure, only the thickness of the inner layer is the total thickness of the inner layer and the intermediate layer in the case of a three-layer structure) is It is 50% or more, preferably 70% or more, and more preferably 50 to 99.5% with respect to the entire layer. In other words, the thickness of the outermost layer made of the polypropylene resin composition is preferably 0.5 to 50%.
If the thickness of this polyethylene resin layer is thin, the drop strength is poor. Further, this thickness can be obtained by adjusting the extrusion ratio for each layer of the multilayer blow molding machine.

3. Capacity of container The preferred capacity of the blow-molded container for liquid dairy products of the present invention is 1000 cc or more. As a beverage container that can be drunk in large quantities every day such as milk, if it is not large to some extent, there is a problem that the amount of container waste after consumption increases, and the container cost corresponding to the volume increases.

4. Structure of Container The structure of the blow-molded container for liquid dairy products of the present invention is not particularly limited, but a preferred structure has a handle structure from the body of the container to the mouth. From the viewpoint of product cost, it is preferable that this handle is formed integrally with the bottle during blow molding. The drawings are an external view and a cross-sectional view showing such a blow-molded container having an integral structure and having a hollow handle portion. In the figure, 1 is a container body, 2 is a mouth part,
Reference numeral 3 denotes a handle portion, 4 denotes a body portion, (a) is a sectional view taken along the line AA 'of the mouth portion, (b) is a sectional view taken along the line BB' of the handle portion, and (c) is a sectional view taken along the line CC of the body portion. 'Represents a cross-sectional view. However, in the same sectional view, the wall thickness of the container may be partially enlarged and displayed. The handle can be molded by a normal blow molding method, and the handle part is generally hollow, but when cleaning the container and recycling it, it is important to make it easy to wash, It is also possible that the handle portion is not hollow. It is possible to manufacture a hollow handle by inserting air into the handle while blow-molding it while retaining air in the handle. On the other hand, if air is removed from the handle and compression-molded with the die, a hollow handle structure can be obtained. it can. In some cases, it can be applied to a blow-molded container without a handle and then to a container having a structure in which a handle portion is joined by mechanical means.

[IV] Liquid dairy product The liquid dairy product of the blow-molded container for a liquid dairy product of the present invention is a liquid at room temperature such as milk, coffee milk, fermented lactic acid bacteria beverage, lactic acid beverage, and at room temperature such as yogurt. It is semi-solid but liquid when filled. Since these products are basically filled without containing a gas such as air, the packing density is higher than powder or solid dairy products, and there is a problem in use unless they are containers excellent in drop strength.

[0041]

The present invention will be described in more detail with reference to the following examples. The evaluation method and test method are shown below.

(1) Melt flow rate (MFR): J
According to IS-K7210, in the case of polypropylene resin, the temperature was 230 ° C. and the load was 2.16 kg. In the case of polyethylene resin, the temperature is 190
The measurement was carried out under conditions of ° C and a working load of 2.16 kg.

(2) Q value: Gel Permeation Chromatography (GPC)
The ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn was measured under the following conditions. GPC device; Waters ISOC-ALC / GP
C solvent; O-dichlorobenzene measurement temperature; 140 ° C. flow rate; 1 m / min standard material; Tosoh monodisperse polystyrene

(3) Method for measuring volatile hydrocarbons: A blow-molded container was cut into small pieces each having a size of several mm and a 5 mg sample was used. The sample was pyrolyzed under the following conditions and analyzed by gas chromatography. (I) Pyrolysis condition Pyrolysis device; PYR-1A made by Shimadzu Corporation Pyrolysis temperature; 210 ° C Pipe temperature; 100 ° C (ii) Condition equipment for gas chromatograph; G-C14B column made by Shimadzu Corporation; G made by Chemicals Inspection Association -100 (40 m, composition;
Methyl Silicone, polarity; non-polarity, film thickness; 1 μm) Column temperature; 60 ° C. → 150 ° C. Calibration curve; n-heptane conversion was performed.

(4) Oligomer measurement method: "Polymer analysis handbook" (published by Kinokuniya Shoten, first edition 1995, first edition,
p. 51, 183) and analyzed by the following method. 2.5 g of the freeze-pulverized sample is heated and refluxed extracted with 100 ml of hexane for 1 hour, cooled, filtered, desolvated by a rotary evaporator and dried to dryness. 4 ml of hexane is added to this and extraction is performed with an ultrasonic washing machine. This was measured by gas chromatography / mass spectrometry (SIM) under the following conditions. Device; HP-GCD column; HP-1 0.23 mm × 30 m Temperature; 100 ° C. → 5 ° C./min→300° C. Injection amount; 1 μl Splitless detection; SIM (m / Z = 43, 57 monitor m / Z =
Quantification at 43 (C18 conversion, absolute calibration curve method) The absolute calibration curve method was based on JIS K 0123.

(5) Odor test method: Prepare a clean odorless wide-mouth glass bottle (300 ml) with a stopper, and put about 80 g of a sample obtained by cutting a blow-molded container into a shape of about 20 × 20 mm into the wide-mouth bottle. . The bottle is capped and placed in a gear oven made by Toyo Seiki heated to 80 ° C. for 2 hours to heat.
It was taken out after heating and evaluated within 10 minutes according to the following odor criteria. Odor standard 0: Not felt 1st: Feeling 2nd: Feeling 3rd: Feeling comfortable 4th: Smell strongly

(6) Taste test method: blow molded wall thickness 1
After treating a 1000 mm mm container with boiling water for 5 minutes or more, 200 ml of coffee milk was put into the container and the mouth was sealed with an aluminum foil for cooking. Then one in the refrigerator 24
Stored for hours. The other is after heating at 80 ℃ for 2 hours,
After allowing to cool at room temperature for 1 hour, it was stored in a refrigerator for 24 hours.
Also, a wide-mouth glass bottle with a stopper that is clean and has no odor 300m
200 ml of coffee milk was added to 1 for comparison.
After each treatment, a sensory test was performed by comparing with the target product of a glass bottle (wide-mouthed bottle). The criterion was expressed by the number of people who felt a difference compared to the glass bottle of coffee milk. (1 /
10 = 1 in 10)

(7) Container gloss test method: The gloss level of the outer surface of the blow-molded container was evaluated visually and by touch.

(8) Drop strength test method: Milk was filled into a bottle container up to the mouth of the bottle, tightly stoppered, and kept at a temperature of 0 ° C. for 12 hours, and then the bottle container 1 from a height of 2 m to a concrete surface.
Zero pieces were dropped and the number of cracks was shown.

Example 1 (1) Polypropylene Resin A Ziegler Natta catalyst was prepared by the following method. <Solid catalyst component 1> 4000 ml of dehydrated / deoxygenated n-heptane was introduced into a flask sufficiently replaced with nitrogen, and then 8 mol of MgCl ₂ and Ti (OnC _4).
16 mol of H ₉ ) 4 was introduced, and the mixture was reacted at 95 ° C. for 2 hours. After the reaction was completed, the temperature was lowered to 40 ° C and then methylhydropolysiloxane (20 centistokes)
960 ml was introduced and reacted for 3 hours. The solid component produced was washed with n-heptane.

Next, 1000 ml of n-heptane purified in the same manner as described above was introduced into a flask that had been sufficiently replaced with nitrogen, and 4.8 mol of the solid component synthesized above was converted in terms of Mg atom. Then, 500 ml of n-heptane was mixed with 8 mol of SiCl ₄ and the mixture was introduced into the flask at 30 ° C. for 30 minutes and reacted at 70 ° C. for 3 hours. After completion of the reaction, it was washed with n-heptane. Then, to 500 ml of n-heptane, 0.4 phthalic acid chloride was added.
After mixing 8 moles, the mixture was introduced into the flask at 70 ° C. for 30 minutes and reacted at 90 ° C. for 1 hour. After completion of the reaction, it was washed with n-heptane. Then, 200 ml of SiCl ₄ was introduced into the flask at 30 ° C. for 30 minutes, and the mixture was heated at 80 ° C. for 6 minutes.
Reacted for hours. After the reaction was completed, it was thoroughly washed with n-heptane to obtain a solid component. Then, n-heptane 1000 purified in the same manner as above was placed in a flask that had been sufficiently replaced with nitrogen.
Introduce 10 ml of the solid component synthesized above by introducing milliliter.
0g _{introduced, (t-C 4 H 9} ) Si (CH 3) (OCH 3)
224 ml, Al (C ₂ H ₅ ) ₃ 34 g at 30 ° C.
For 2 hours. After the contact was completed, it was thoroughly washed with n-heptane to obtain a solid catalyst component mainly composed of MgCl ₂ . The titanium content of this solid catalyst component was 1.1% by weight.

<Polymerization Method 1> Using the above Ziegler-Natta catalyst, a propylene / ethylene random copolymer powder was produced by the following gas phase polymerization method. By using a stirring type continuous gas phase polymerization reaction device comprising a reactor having an internal volume of 10 L,
Continuous production of propylene-ethylene random copolymer was carried out. First, the inside of the reactor was replaced with sufficiently purified nitrogen, and then 2.2 kg of polymer carrier that was sufficiently dehydrated and deoxygenated.
After filling, the gas was sufficiently replaced with propylene. The hydrogen and ethylene used in combination were controlled by the hydrogen concentration and ethylene concentration in the gas phase. Triethylaluminum and the solid catalyst component were continuously introduced to adjust the polymerization temperature to 7
Propylene-ethylene random copolymerization was continuously carried out at 5 ° C. and a total pressure of 14.5 kg / cm 2. The copolymerized powder was extracted intermittently. Thus, a powdery propylene-ethylene random copolymer was obtained.

In order to deodorize the obtained propylene-ethylene random copolymer powder, a gear oven manufactured by Toyo Seiki Co., Ltd. was used to carry out a reinforced drying treatment at 80 ° C. for 60 minutes while flowing a small amount of nitrogen (about 1000 ml / min). . With respect to 100 parts by weight of the powder that has been subjected to this enhanced drying treatment,
As a phenolic antioxidant, 0.1 part by weight of pentaerythyl-tetrakis [3- (3,5-t-butyl-4-hydroxyphenyl) propionate] (manufactured by Ciba Specialty Chemicals; hereinafter abbreviated as IR1010), As a phosphorus-based antioxidant, 0.1 part by weight of tris (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals; hereinafter abbreviated as IR168), and as a neutralizing agent calcium stearate 0. 05 parts by weight was added, and the mixture was sealed with nitrogen using a super mixer and mixed for 3 minutes. Then, using a 30 mmD extruder, the hopper was granulated and pelletized at 230 ° C. while sealing the hopper with nitrogen. The obtained propylene / ethylene random copolymer composition had an MFR of 12 g / 10 minutes and an ethylene content of 3.2.
% By weight.

(2) Polymerization of ethylene and butene-1 with isopentane as a solvent in an autoclave using an inorganic chromium catalyst (Phillips catalyst) obtained by firing chromium oxide using polyethylene resin silica as a carrier, The solvent of this ethylene-butene-1 copolymer was separated by a centrifugal separator and taken out. Then, in order to deodorize the powder, use a gear oven manufactured by Toyo Seiki Co., Ltd. while flowing a small amount of nitrogen (about 1000 ml per minute) 8
Drying treatment was performed at 0 ° C. for 60 minutes. The powder subjected to this drying treatment was granulated and pelletized at 200 ° C. using a 30 mmD extruder while sealing the hopper with nitrogen. The obtained ethylene-butene-1 copolymer has MFR =
0.3 g / 10 minutes, butene-1 content = 0.5% by weight.

(3) Container molding Inner layer 50 mmD, outer layer 40 mmD, middle layer 40 mmD extruder and direct blow molding machine having a spiral type multilayer round die. The polyethylene resin pellet sample was used as the inner layer and the polypropylene resin was used as the outer layer. The composition pellets were directly blended in the middle layer under the conditions of a molding temperature of 200 ° C and a mold temperature of 20 ° C by supplying pellets obtained by dry blending the polyethylene resin pellets and the polypropylene resin composition in the same weight ratio. Blow molding was carried out to form a round container having a shoulder cavity type handle with a capacity of 1000 cc, a weight of 75 g, and a body wall thickness of about 0.6 mm.
The thickness ratio of each layer is 50% for the inner layer, 10% for the intermediate layer, and 4 for the outer layer.
The ratio is 0%. Table 1 shows the results of evaluation of the amount of volatile hydrocarbons and odor of the obtained blow-molded container, taste of coffee milk using this container during storage, heating taste, and gloss and drop strength of the container.

Example 2 (1) Polypropylene-based resin Using the solid catalyst (Ziegler Natta-based catalyst) of Example 1, a propylene / ethylene random copolymer powder was produced by the following slurry polymerization method. <Polymerization method 2> After thoroughly replacing the inside of a stirring type polymerization tank having an internal volume of 200 liters with propylene, 60 liters of dehydrated and deoxygenated n-heptane were introduced, and 15.0 g of triethylaluminum and the solid catalyst component 3 were introduced. 0.0 g was introduced at 60 ° C. in a propylene atmosphere. Next, after raising the temperature in the polymerization tank to 65 ° C., propylene was added at 5.9 kg /
For a time, ethylene was introduced at a feed rate of 0.04 kg / hour, and the amount of hydrogen used together was controlled by the hydrogen concentration in the gas phase. Then, the introduction of propylene and ethylene was stopped, and the temperature in the polymerization tank was continued at 65 ° C. for 90 minutes. The slurry thus obtained is filtered and dried under reduced pressure (80
C., 3 hours) to obtain 32.0 kg of powdery propylene / ethylene random copolymer. The powder thus obtained is subjected to a strengthening drying treatment at 90 ° C. for 3 hours while flowing a slight amount of nitrogen (about 1000 ml / min) in order to accelerate the removal of volatile components using a gear oven manufactured by Toyo Seiki Co., Ltd. went. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene / ethylene random copolymer composition had MFR =
It was 14 g / 10 minutes and the ethylene content = 3.2% by weight.

(2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 1.

Example 3 (1) Polypropylene Resin Using the solid catalyst (Ziegler Natta catalyst) of Example 1, a propylene homopolymer powder was produced by the following gas phase polymerization method. <Polymerization Method 3> A propylene homopolymer was continuously produced by using a stirring type continuous gas phase polymerization reaction apparatus including a reactor having an internal volume of 10 L. First, the inside of the reactor was purged with nitrogen that had been sufficiently purified, and then 2.2 kg of a polymer carrier that had been thoroughly dehydrated and deoxygenated was filled, and then the gas was sufficiently purged with propylene. The hydrogen used together was controlled by the hydrogen concentration in the gas phase. Further, triethylaluminum and the solid catalyst component were continuously introduced, the polymerization temperature was 75 ° C., and the total pressure was 1
Propylene homopolymerization was continuously carried out at 4.5 kg / cm ² . The polymerized powder was intermittently withdrawn. The powder thus obtained is dried at 80 ° C. for 60 minutes using a gear oven manufactured by Toyo Seiki Co., Ltd. while promoting the removal of volatile components while flowing a small amount of nitrogen (about 1000 ml / min). A powdery propylene homopolymer was obtained. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene homopolymer composition had MFR = 13 g / 10 minutes.

(2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 1.

Example 4 (1) Polypropylene Resin Except that the hydrogen concentration was changed during the polymerization of Example 1.
It polymerized similarly. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene / ethylene random copolymer composition has MFR
= 3 g / 10 minutes. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 1.

[Example 5] (1) Polypropylene resin In the polymerization of Example 1, except that the hydrogen concentration was changed,
It polymerized similarly. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene / ethylene random copolymer composition has MFR
= 1 g / 10 minutes. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 1.

[Comparative Example 1] (1) Polypropylene-based resin The strengthening drying treatment carried out in Example 1 (8 while flowing nitrogen)
A propylene / ethylene block copolymer was obtained in the same manner as in Example 1 except that the deodorizing treatment of treating at 0 ° C. for 60 minutes) was omitted. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene / ethylene random copolymer composition had MFR = 12.
It was g / 10 minutes. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 2.

[Comparative Example 2] (1) Polypropylene-based resin The reinforced drying treatment carried out in Example 2 (9 while flowing nitrogen)
A propylene / ethylene block copolymer was obtained in the same manner as in Example 2 except that the deodorizing treatment of 3 hours at 0 ° C.) was omitted. Thereafter, in the same manner as in Example 1, a phenol-based antioxidant, a phosphorus-based antioxidant and calcium stearate were added, and the mixture was granulated and pelletized. The obtained propylene / ethylene random copolymer composition had MFR = 14 g.
/ 10 minutes. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 2.

[Example 6] (1) Polypropylene-based resin The additive formulation of Example 1 was used as a phenol-based antioxidant, 0.1 part by weight of IR1010, and as a neutralizing agent, only 0.05 part by weight of calcium stearate. Same as Example 1 except that After granulation, the obtained propylene / ethylene random copolymer composition has MFR = 12 g / 10
It was a minute. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 2.

Example 7 (1) Polypropylene Resin In the additive formulation of Example 1, the phenolic antioxidant IR1010 was not used, but dimethyl succinate-1 was used as a hindered amine (HARS) stabilizer instead. −
(2-hydroxyethyl) -4-hydroxy-2,2
Example 1 was repeated except that 0.1 part by weight of 6,6-teotramethylpepyridine polycondensate (manufactured by Ciba Specialty Chemicals; hereinafter abbreviated as TNV622) was used. After granulation, the obtained propylene / ethylene random copolymer composition had MFR = 12 g / 10 minutes. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 2.

Comparative Example 3 (1) Polypropylene resin Example 1 except that the additive formulation of Example 1 was changed to no addition
Same as. After granulation, the propylene / ethylene random copolymer obtained had MFR = 20 g / 10 minutes. This indicates that MFR increased due to thermal decomposition of the polymer because no stabilizer was added in the granulation step. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1. The evaluation results of the molded container are shown in Table 2.

Comparative Example 4 (1) Polypropylene Resin The same resin as in Example 1 was used. (2) Polyethylene resin is not used. (3) Inner layer 50 mmD, outer layer 40 mmD used in the container molding example 1,
In a direct blow molding machine having an intermediate layer extruder of 40 mmD and a spiral type multi-layer round die, a resin material is not supplied to the inner layer extruder and the intermediate layer extruder, and only the outer layer extruder is operated to obtain a polypropylene resin composition. Molding was attempted under the same conditions as in Example 1 except that the single layer molding was replaced with. However, molding was impossible due to drawdown, and a molded product worthy of evaluation could not be obtained. The results are shown in Table 3.

Comparative Example 5 (1) Polypropylene resin was not used. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Inner layer 50 mmD, outer layer 40 mmD used in the container molding example 1,
In a direct blow molding machine having an intermediate layer extruder of 40 mmD and a spiral type multi-layer round die, the resin material is not supplied to the outer layer extruder and the intermediate layer extruder, only the inner layer extruder is operated, and the polyethylene resin Molding was tried under the same conditions as in Example 1 except that the layer molding was replaced. This Comparative Example 5
However, unlike the single layer molding of the polypropylene resin composition, the molding operation was successful. Table 3 shows the evaluation results of the molded containers.

[Example 8] (1) Polypropylene resin The same resin as in Example 1 was used. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Container molding Blow molding was performed under the same conditions as in Example 1 except that the resin for the intermediate layer was not supplied to the extruder and the intermediate layer was omitted. Table 3 shows the evaluation results of the molded containers.

[Example 9] (1) Polypropylene resin The same resin as in Example 1 was used. (2) Polyethylene resin The same resin as in Example 1 was used. (3) Inner layer 50 mmD, outer layer 40 mmD used in the container molding example 1,
In a direct blow molding machine having an intermediate layer 40 mmD extruder and a spiral-type multilayer round die, the extrusion ratio of the outer layer extruder and the inner layer extruder is adjusted by adjusting the screw rotation speed, and the thickness ratio of each layer is 30% for the inner layer and the middle layer. 10%, outer layer 60%
Example 1 was repeated except that the ratio was set to. Table 3 shows the evaluation results of the molded containers.

Example 10 (1) Polypropylene Resin The same resin as in Example 1 was used. (2) Polyethylene resin The same resin as in Example 1 was used. (3) The container molding machine and molding conditions are the inner layer of 50 m used in Example 1.
mD, outer layer 40mmD, middle layer 40mmD extruder and direct blow molding machine with spiral type multi-layer round die, except that the container capacity was changed to a round capacity 2000cc with a shoulder cavity type handle and a weight of 150g. Molded under the same conditions as in Example 1. Table 3 shows the evaluation results of the molded containers.

[0072]

[Table 1]

[0073]

[Table 2]

[0074]

[Table 3]

[0075]

EFFECTS OF THE INVENTION According to the present invention, a blow-molded container having a multi-layer structure for liquid dairy products, which is excellent in odor and taste, and is also excellent in surface gloss, drop strength and handleability, can be obtained.

[Brief description of drawings]

FIG. 1 shows an external view and a sectional view of a blow-molded container having a structure with a grip according to the present invention.

[Explanation of symbols]

1: Container body 2: Mouth 3: Handle part 4: Body 5: Outer layer 6: Inner layer 7: Middle layer (A): A, A'cross sectional view (mouth sectional view) (B): B, B'cross sectional view (handle sectional view) (C): C, C'cross-sectional view (body sectional view)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3E033 AA02 BA15 BA16 BB04 BB08                       CA03 CA20 DA02 DB01 DD01                       DE02 FA03 GA02                 4F100 AA17A AC10A AH01A AH02H                       AH03H AH08H AH10H AK04B                       AK04C AK07A AK07C AL03A                       AL03C AL05C BA02 BA03                       BA07 BA10A BA10B CA06A                       DA01 GB16 JA06A JK10                       JL05 JN21 YY00A                 4J002 BB121 BB141 DE078 DE148                       DE188 DE288 EG028 EG038                       EG048 EJ016 EJ066 EJ077                       EW049 EW069 FD047 FD049                       FD076 FD208 GF00 GG01

Claims (7)

[Claims] 1. A polypropylene resin composition containing (a) a phenolic antioxidant and / or a hindered amine stabilizer and (b) a neutralizing agent in the outermost layer and a polyethylene resin in the innermost layer. A blow molding container for a liquid dairy product, which has a multi-layered structure including at least one layer and has a volatile hydrocarbon having 6 to 10 carbon atoms of 300 ppm or less and an oligomer component having 11 to 30 carbon atoms of 600 ppm or less. 2. The blow molding container for liquid dairy products according to claim 1, wherein the polypropylene resin composition further contains (C) a phosphorus antioxidant. 3. The blow molding container for liquid dairy products according to claim 1, wherein the neutralizing agent is at least one selected from fatty acid metal salts, hydrotalcite, and metal hydroxide salts. 4. The blow molding container for liquid dairy products according to claim 1, wherein the polypropylene resin is a polypropylene random copolymer having a melt flow rate of 3 g / 10 minutes or more. 5. An intermediate layer made of a mixture of a polypropylene random copolymer and a polyethylene-based resin is provided between the outermost layer and the innermost layer, and the intermediate layer is provided. Blow molding container for liquid dairy products. 6. The liquid dairy product according to any one of claims 1 to 5, wherein the outermost layer of the polypropylene resin composition has a thickness of 0.5 to 50% of the total layer. Blow molded container. 7. The blow-molded container for liquid dairy products according to any one of claims 1 to 6, which has a capacity of 1000 cc or more and has a handle structure extending from the body of the container to the mouth.