JP3369507B2 - Blow molded container - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-layer or multi-layer blow molding container in which at least an inner layer is a polyamide layer.

[0002]

2. Description of the Related Art In recent years, single-layer or multi-layer blow-molded containers having a polyamide inner layer have been widely used because of their excellent mechanical properties, heat resistance, chemical resistance and gas barrier properties. ing. In particular, such blow-molded containers are often used by being filled with liquids or solids such as gasoline, chemicals, organic solvents, etc. It is important commercial value that they have excellent impact strength and sealability for safety. ing. However, since such a blow-molded container has a weak adhesive strength at the pinch-off portion, it has a problem that the pinch-off portion is likely to tear due to an impact.

Conventionally, in order to improve the adhesive strength of the pinch-off portion of this blow-molded container, a method is adopted in which the adhesive area of the pinch-off portion is widened, or a mold structure is applied to the pinch-off portion with a strong pressure as much as possible. Is taken,
I am using nitrogen for blow air. However, the shape of the pinch-off part can be changed significantly,
In many cases, the method of improving the mold structure has restrictions on the design of the container, and molding with nitrogen as blow air requires modification of the molding machine or supply of nitrogen. It will not be easy.

On the other hand, as an improvement in terms of resin used, there is a method of improving adhesive strength of a pinch-off portion by adding a copper halide or its derivative to a polyamide resin (Japanese Patent Publication No. 57-2579). . This method is effective in improving the adhesive strength of the pinch-off part, but it has the drawback that the appearance color tone of the molding container changes to blue or yellow-green over time due to the copper ions originating from copper halide, so its application is limited. Occurs. That is, in the case of a colored product or the like, the color tone is darkened due to the interaction between the pigment and the copper halide, and thus the color tone is difficult to be adjusted. Further, there are methods (JP-A-2-281924 and JP-A-3-32815) in which this defect is improved by adding a phosphorus-based heat-resistant agent instead of copper halide, but the color tone is good. However, the adhesive strength of the pinch-off part is insufficient.

[0005]

The inventors of the present invention have completed the present invention as a result of intensive studies to solve such problems, and the purpose thereof is to bond the pinch-off portion. It is an object of the present invention to provide a blow-molded container having improved strength and excellent organic solvent resistance which is not restricted by color tone and design of the container.

[0006]

The above-mentioned object is achieved by a blow molding container of a single layer or a multilayer, characterized in that the inner layer is formed of a polyamide layer containing a manganese compound. .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyamide of the present invention includes nylon 6, nylon 66, nylon 12, nylon 46, copolymerized nylon, semi-aromatic nylon and the like, and is generally called nylon. , Those containing additives such as dyes, lubricants, plasticizers, stabilizers, flame retardants, reinforcing agents, colorants, ultraviolet absorbers and antioxidants are also included. Further, not only the polyamide homopolymer but also an alloy product obtained by mixing polyamide, polypropylene, polyphenylene ether, ionomer and the like may be used.

The amount of the manganese compound added to the polyamide is preferably 1 to 1000 ppm as the manganese atom, and most preferably 10 to 500 p as the manganese atom.
pm. If the amount of manganese atoms added is less than 1 ppm, the effect of improving the adhesive strength is small, and if it is more than 1000 ppm, the color tone of the molded product tends to deteriorate, and the value of the molded product decreases.

As the manganese compound, manganese acetate,
Manganese benzoate, manganese naphthenate, manganese stearate, manganese phosphite, manganese sulphate, manganese chloride and the like are preferable, and those soluble in polyamide are preferable, but even if other compounds are mixed to make them soluble in polyamide, I do not care.

In the conventional method using copper halide, it was necessary to wash with an expensive solvent such as triethylene glycol as necessary so that the machine used for kneading with polyamide is not corroded by halogen. Manganese or the like is particularly preferable because it does not require cleaning and can reduce such trouble and cost.

As the method of adding the manganese compound to the polyamide, (1) a method of adding at the time of polymerization, (2) a method of dry blending a finely pulverized manganese compound into polyamide pellets, and (3) melt-kneading the compound. Machine, high filling, master pellets added to polyamide, (4) dry blend of manganese compound adsorbed on porous nylon powder to polyamide,
However, the powder adsorption method (4) is most preferable because it does not require the trouble of finely pulverizing the manganese compound and can improve the strength of the pinch-off portion with a small amount.

The average particle size of the porous nylon powder used for powder adsorption is preferably 100 μm or less, more preferably 5 to 50 μm. Its specific surface area is 0.5 m ² / g
It is preferably at least 2 m ² / g and more preferably at least 2 m ² / g.

Powder adsorption can be carried out as follows. Porous nylon powder is put into a manganese compound dissolved in a solvent such as methanol and the mixture is stirred.
After removing the solvent by a rotary evaporator, it is dried by a vacuum dryer.

In the present invention, by using the reducing agent together with the manganese compound, the effect of improving the adhesive strength of the pinch-off portion and the effect of preventing the coloring of the polyamide can be further enhanced.

As the reducing agent, sodium hypophosphite,
Examples include sodium pyrophosphate and potassium iodide. In particular, potassium iodide can remarkably enhance the effect when used in combination with another reducing agent.

When a reducing agent is used, it may be mixed with a manganese compound in advance and then subjected to masterbatch, powder adsorption or the like.

The blow molded container of the present invention is molded by a generally known blow molding method. For example, a three-layer oil tank of polyamide / adhesive layer / polyethylene can be molded using an accumulator blow molding machine. When blow molding is carried out, if the inner layer is polyamide, generally the adhesion of the pinch-off part tends to be poor,
When a polyamide containing a manganese compound is used, a pinch-off portion having sufficient adhesive strength can be formed, and a blow molded product having excellent impact strength and barrier properties can be obtained. The blow-molded container in which the copper halide is added to the polyamide disclosed in JP-B-57-2579 satisfies the adhesive strength at the pinch-off part, but when the polyamide absorbs moisture, the color changes to blue or green over time. I will end up. However, the blow-molded container using the polyamide containing the manganese compound of the present invention satisfies the adhesive strength of the pinch-off portion, and at the same time, a beautiful blow-molded product which is peculiar to polyamide and has no discoloration with time or transparent or milky white can be obtained. .
Also, in the case of coloring with a color color, Japanese Patent Publication No. 57-2579.
In the method disclosed in the publication, it is difficult to adjust the color because it darkens due to the interaction between the pigment and the copper compound, and it is impossible to adjust a particularly vivid color, but the blow-molded container of the present invention does not darken, so Color is easy.

[0018]

EFFECTS OF THE INVENTION Blow-molded containers have good moldability and good appearance color tone, and there is a problem that the color tone changes with time, for example, when copper halide is used, and the color tone becomes dark when the color product is toned. Does not happen. In addition, the effect of extremely increasing the adhesive strength and impact strength of the pinch-off portion appeared by simply adding the manganese compound to the polyamide.

Hereinafter, the present invention will be described in detail with reference to Examples. Prior to that, the methods for testing the tensile breaking strength and the tensile impact strength used in the Examples will be described.

[0020]

[Tensile breaking strength] The bottom pinch part of the container molded as in the example was cut into a width of 10 mm and a length of 40 mm as shown in FIG.
The measurement was performed according to ASTM D638 (cross head speed 5 mm / min, chuck distance 20 mm). The test machine used was Tensilon UCT500 manufactured by Orientec Co., Ltd.

[0021]

[Tensile Impact Strength] As shown in FIG. 4, the bottom pinch portion of the container molded as in the example was cut into a width of 3 mm and a length of 40 mm, and
It measured according to STM D1822. The measuring machine was a Tensile Impact Tester from Toyo Seiki Co., Ltd.

[0022]

Example 1 4.4 g of manganese (II) acetate tetrahydrate,
20 g of sodium hypophosphite and 20 g of potassium iodide
g was weighed, externally added to 1 kg of 6 nylon, kneaded with a single screw extruder, and pelletized. The pellets were mixed with blow-moldable high-viscosity 6-nylon pellets in an amount of 5% by weight, and the length was 300 m by a single-layer blow molding machine.
A 500 cc container having a diameter of 70 mm and a diameter of 70 mm was blow-molded.
When the cross section of the pinch-off portion of the blow container thus obtained was confirmed, the adhesion was good (FIG. 1). Also,
The adhesiveness (tensile breaking strength and tensile impact strength) of the pinch-off part was measured. The results are shown in Table 1.

Further, the color difference between the surface of the bottle immediately after molding and the surface of the bottle after being left in the room after molding for one month was measured with a color difference meter (manufactured by Suga Test Instruments Co., Ltd.), and numerical values were obtained. However, no change in color tone was observed at 0.3.

When a white pigment master chip was added in the same manner and blow molding was performed, the same color tone as that of a molded product to which no manganese compound was added was obtained.

[0025]

Example 2 4.4 g of manganese (II) acetate tetrahydrate was weighed, externally added to 1 kg of 6 nylon, melt-kneaded with a biaxial kneader to form pellets. The pellets were mixed with blow-moldable high-viscosity 6-nylon pellets so as to be 20% by weight, and a single-layer blow molding machine was used to blow-mold a 500 cc bottle having a length of 300 mm and a diameter of 70 mm in the same manner as in Example 1. did. The adhesive strength of the pinch-off part of the blow bottle thus obtained (tensile breaking strength and tensile impact strength)
Was measured. The results are shown in Table 1.

[0026]

Example 3 Manganese (II) acetate tetrahydrate was weighed in an amount of 4.4 g, finely pulverized, and then dry-blended into 5 kg of blow-moldable high-viscosity nylon 6 to form a single layer as in Example 1. Blow molding machine, length 300mm, diameter 70m
m 500 cc bottle was blow molded. The adhesive strength (tensile breaking strength and tensile impact strength) of the pinch-off portion of the blow bottle thus obtained was measured. The results are shown in Table 1.

[0027]

Example 4 10 g of manganese (II) acetate tetrahydrate was weighed and completely dissolved in 200 cc of water-containing methanol in which pure water and methanol were mixed at a ratio of 50/50. 90 g of porous 6 nylon powder (average particle size: 20 μ, specific surface area: 3.0 m ² / g) was put into this, and the mixture was made into a slurry and stirred well. Next, hydrous methanol is removed from this slurry using an evaporator, and manganese (II) acetate tetrahydrate is adsorbed on the porous 6 nylon powder. After drying this powder with a vacuum dryer (90 ° C, 8 hours),
6 Nylon was dry blended to 0.9% by weight, and a 500 cc bottle having a length of 300 mm and a diameter of 70 mm was blow molded by a single layer blow molding machine in the same manner as in Example 1. The adhesive strength (tensile breaking strength and tensile impact strength) of the pinch-off portion of the blow bottle thus obtained was measured. The results are shown in Table 1.

[0028]

Example 5 Manganese (II) acetate tetrahydrate (8 g) and sodium hypophosphite (12 g) were weighed and mixed with pure water and methanol at 50/50 to give 200 cc of water-containing methanol.
Completely dissolves in. 90g of porous 6 nylon powder (average particle size 20μ, specific surface area 3.0m ² / g) in this
Put in, make a slurry, and stir well. Next, the slurry was used to remove hydrous methanol using an evaporator, and porous 6 nylon powder was converted to manganese (II) acetate.
Adsorb tetrahydrate and sodium hypophosphite. After drying this powder with a vacuum dryer (90 ° C, 8 hours),
6 Nylon was dry-blended to 0.6% by weight, and a 500 cc bottle having a length of 300 mm and a diameter of 70 mm was blow molded by a single layer blow molding machine in the same manner as in Example 1. The adhesive strength (tensile breaking strength and tensile impact strength) of the pinch-off portion of the blow bottle thus obtained was measured. The results are shown in Table 1.

[0029]

[Comparative Example 1] Blow-moldable high-viscosity 6-nylon pellets having a length of 300 mm were blown by a single-layer blow molding machine.
A 500 cc container having a diameter of 70 mm was blow molded. The cross section of the pinch-off portion of the blow container thus obtained was photographed and the adhesion state was confirmed. The adhesion portion had a valley shape (FIG. 2). In addition, the adhesiveness (tensile breaking strength and tensile impact strength) of the pinch-off portion was measured. The results are shown in Table 1.

[0030]

Comparative Example 2 Blow-moldable high-viscosity 6-nylon pellets with phosphorus-based antioxidant (Ciba Geigy, lrg)
afos 168) was dry blended to 0.5% by weight, and this was blended with a single layer blow molding machine to a length of 3
A 500 cc bottle having a diameter of 00 mm and a diameter of 70 mm was blow molded. The cross section of the pinch-off portion of the blow container thus obtained was photographed and the adhesion state was confirmed. The adhesion portion had a valley shape (FIG. 3). In addition, the adhesive strength (tensile breaking strength and tensile impact strength) of the pinch-off portion was measured. The results are shown in Table 1.

[0031]

Example 6 A 5% aqueous solution of manganese sulfate and an aqueous solution of 5% sodium pyrophosphate are mixed and stirred with a homomixer, and the produced precipitate is filtered and purified (manganese pyrophosphate). This was dry-blended to 6 nylon as manganese at 70 ppm, and a single layer blow molding machine was used in the same manner as in Example 1 to obtain 500 cc of 300 mm in length and 70 mm in diameter.
The container was blow molded. The adhesive strength (tensile breaking strength and tensile impact strength) of the pinch-off portion of the blow container thus obtained was measured. The results are shown in Table 1.

[0032]

[Comparative Example 3] 6 nylon pellets with copper iodide (CuI)
Was blended with 0.05% by weight and potassium iodide (KI) with 0.5% by weight, and a single layer blow molding machine was used in the same manner as in Example 1 to obtain 50 having a length of 300 mm and a diameter of 70 mm.
A 0 cc container was blow molded. Although the adhesion state of the pinch-off part of the blow container thus obtained was good, the color tone of the bottle surface immediately after molding and after molding and after leaving it in the room for one month was measured with a color difference meter and the values were measured. It was found that the color difference was as large as 6.8 when it was changed to blue.

When a white pigment master chip was added and blow molding was carried out in the same manner as this method, the color tone was dark and the target whiteness could not be obtained.

[0034]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pinch-off portion of a blow-molded container manufactured in Example 1.

2 is a cross-sectional view of a pinch-off portion of a blow-molded container manufactured in Comparative Example 1. FIG.

FIG. 3 is a cross-sectional view of a pinch-off portion of a blow-molded container manufactured in Comparative Example 2.

FIG. 4 is a view showing the bottom of the blow-molded container of the present invention.

[Explanation of symbols]

1 Pinch off part 2 Pinch off part 3 Pinch off part 4 Polyamide layer 5 Polyamide layer 6 Polyamide layer 7 Blow molded container bottom 8 Pinch off part 9 Sample site for tensile breaking strength test

Claims (2)

(57) [Claims] 1. A single-layer or multi-layer blow-molded container, wherein the inner layer contains a manganese compound of 10 ppm or more and 500 pp.
characterized by being formed of a polyamide layer containing less than m
Blow molded container with pinch-off section . 2. A single-layer or multi-layer blow molded container
The inner layer contains manganese compound of 50 ppm or more and 200 pp
characterized by being formed of a polyamide layer containing less than m
Blow molded container with pinch-off section .