JP2000355352A - Molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably maintain a flavor for a long period of time for contents in a packaging container by a method wherein the packaging container is made up of a molding which is formed of a material including a thermoplastic resin and a carbon dioxide low permeable resin having a specified carbon dioxide gas permeability constant respectively in a specified percentage. SOLUTION: A molding is formed of a material including a thermoplastic resin in 30-99 wt.% and a carbon dioxide low permeable resin having its carbon dioxide permeability constant (JIS K7126-87) set below 1.0×10-17 mol×m/(m2×s×Pa) in 70-1 wt.%. For the thermoplastic resin, a polyolefine resin, a polyolefin elastomer and a styrene elastomer are used, and its monodispersion (weight average molecular weight/number average molecular weight) measured by a gel permeation chromatography is set as 1.5-3.0. Furthermore, for the carbon dioxide low permeable resin, an ethylene-vinyl alcohol copolymer and a polyamide resin are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article containing a cap liner, which has a low permeability to carbon dioxide, and is effective for use in packaging of foods and beverages. Especially in the case of a cap liner, when used as a cap for a bottle of content to which carbon dioxide such as carbonated drinking water has been added, prevent leakage of carbon dioxide,
It is possible to maintain the flavor of the contents for a long time.

In addition, the permeability of carbon dioxide is almost proportional to that of oxygen, and since it has low permeability to oxygen, oxygen permeates through the cap liner into the bottle, and the contents are removed. Oxidation also prevents the flavor from being impaired.

[0003]

2. Description of the Related Art Molded articles are generally produced by various molding methods using generally known thermoplastic resins. In the case of the cap liner, generally, a composition such as hydrogenated styrene-conjugated diene block copolymer rubber and liquid paraffin (Japanese Patent Publication No. 6-88608) is suitably used as the material for the cap liner. .

[0004] Large carbonated drinking water PET bottles (2.0 l
Type and 1.5 liter type), the leakage of carbon dioxide from the cap portion is a very small ratio compared to the leakage of carbon dioxide from the bottle portion having a large surface area, and cares much. The problem was not.

[0005] However, small carbonated drinking water PET bottles (50) which have recently been introduced to the market and whose quantity has increased dramatically have been increasing.
In the case of 0 ml type and 350 ml type), the leakage of carbon dioxide in the cap portion is not negligible compared to the leakage in the bottle portion having a reduced surface area, and the flavor inhibition due to the leakage of carbon dioxide is reduced from the cap portion. Leakage of carbon dioxide has also become a cause and is becoming a problem.

[0006] This is in the same situation as when the contents are oxidized due to the inflow of oxygen, and the taste is inhibited.

[0007] Therefore, there has been a demand for a cap liner which prevents the bottle contents from hindering the flavor.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molded article including a cap liner having low carbon dioxide permeability, which has been made in view of the above-mentioned conventional technical problem. .

[0009]

Means for Solving the Problems Accordingly, the present inventors have conducted intensive studies, and as a result, by using a molded body composed of a thermoplastic resin and a resin having a carbon dioxide low permeability performance of a certain value or less, The inventors have found that the flavor of the contents in a packaging container using the molded body can be maintained for a long period of time, and have completed the invention.

That is, the present invention relates to a thermoplastic resin (a) 3
0-99% by weight and carbon dioxide gas permeability coefficient (JIS
K7126-87) is 1.0 × 10 ⁻¹⁷ mol × m /
(M ² × s × Pa) or less, a molded article composed of 70 to 1% by weight of carbon dioxide low permeability resin (b).

The thermoplastic resin used in the present invention (a)
Examples thereof include polyolefin-based resins, polyolefin-based elastomers, polyester-based resins, ABS resins, styrene-based resins, and styrene-based elastomers. When the molded article is used for a cap liner, generally known compositions for cap liner materials can be used. Specifically, it is at least one resin selected from the group consisting of polyolefin-based resins, polyolefin-based elastomers, and styrene-based elastomers. Specifically, high-density polyethylene, linear low-density polyethylene, branched low-density polyethylene, polyethylene,
Ethylene-vinyl acetate copolymer, ethylene-propylene copolymer rubber, ethylene-butene copolymer rubber, styrene-butadiene block copolymer rubber, styrene-ethylene-butylene block copolymer rubber, styrene-ethylene-propylene block There are copolymer rubber, styrene-isoprene block copolymer rubber, and the like.

[0012] Among the polyolefin resins, gel
Monodispersity (weight average molecular weight / number average molecular weight) in permeation chromatography measurement is 1.5 to
It is more preferable to use a polyolefin-based resin characterized by being in the range of 3.0, because it has less hindrance to the contents. The method for measuring Mw and Mn was determined by gel permeation chromatography (manufactured by Nippon Millipore Co., Ltd., apparatus name "ALC / GPC150C" (column: Tosoh Corporation, trade name "GMHHR-H (S)" 3). Book,
Solvent: 1,2,4-trichlorobenzene, temperature: 140
, A flow rate of 1.0 ml / min, an injection concentration of 1 mg / 1 ml, and an injection volume of 300 μl). The column elution volume was calibrated by universal calibration using standard polystyrene manufactured by Tosoh Corporation.

The low carbon dioxide permeable resin (b) used in the present invention is a polyvinyl alcohol resin, ethylene-
Examples thereof include a vinyl alcohol copolymer, a polyamide resin, a vinyl chloride resin, and a vinylidene chloride resin.

Among them, ethylene is easily compounded with the thermoplastic resin (a) and has excellent carbon dioxide low permeability.
Vinyl alcohol copolymer (trade name: EVAL manufactured by Kuraray Co., Ltd., Soarnol manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), polyamide resin (nylon manufactured by Ube Industries, Nylon manufactured by Unitika, Nylon manufactured by Kanebo Co., Ltd.) The carbon dioxide gas permeability coefficient (JIS K7126-87) of the low-permeability carbon dioxide resin (b) is 1.0 × 10 ^−17.
mol × m / (m ² × s × Pa) or less and 1.0 ×
If it exceeds 10 ⁻¹⁷ mol × m / (m ² × s × Pa), it is difficult to lower the carbon dioxide permeability of the molded body.

The molded article of the present invention contains 30 to 99% by weight, preferably 50 to 90% by weight of the above-mentioned thermoplastic resin (A), 70 to 1% by weight of the low-permeability carbon dioxide resin (B), Preferably, it is composed of 50 to 10% by weight.

When the content of the thermoplastic resin (a) is less than 30% by weight, the ratio of the hard carbon dioxide low-permeability resin (b) is generally large, so that the molded body is hard and brittle, so that it is inferior.

On the other hand, if the content of the thermoplastic resin (a) exceeds 99% by weight, the amount of the low carbon dioxide permeable resin is too small, and the effect of low carbon dioxide permeability of the molded product cannot be obtained.

The molded article of the present invention includes films, sheets, trays, cups, bottles, caps, gaskets, etc. produced by molding methods such as film, sheet, press, blow, and injection. After mixing the thermoplastic resin (a) and the carbon dioxide low-permeability resin (b) with various methods known in the above range, for example, using a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, etc. Using a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, etc., melt-kneading and granulating or pulverizing, or using a dry-blended product without prior melt-kneading, or a method using an auto feeder, Create a sheet of any thickness with etc., punch it into any shape,
Adhesion is applied to the top surface of the cap using an adhesive, or the punched material is melted / semi-fused and then glued to the top surface of the cap. In this state, the cap is cut out on the top surface inside the cap, the cut out composition is immediately pressed, cooled, and molded into a cap liner shape by an in-shell molding method to obtain a cap liner and a cap provided with the cap liner. Is preferably used.

In the molded article of the present invention, if necessary, heat stabilizers, weather stabilizers, antistatic agents, antiblocking agents, slip agents, surfactants, antifogging agents, dropping agents, crosslinking agents, nucleating agents , Pigments, dyes, silica, talc, mica, carbon,
Inorganic or organic additives and fillers such as calcium carbonate, magnesium carbonate, metal stearate, wood flour, cork powder, and cellulose powder may be blended as long as the object of the present invention is not impaired. Among them, the cap liner often uses a slip agent to adjust the cap opening torque, especially higher fatty acid amide,
Higher fatty acids, glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters,
Higher alcohol fatty acid esters, ethylene bis higher fatty acid amides and the like are used, and preferably, higher fatty acid amides are used. Specifically, caprylic amide, capric amide, lauric amide, myristic amide, palmitic amide, stearic amide, arachidic amide, behenic amide, oleic amide, erucic amide, linoleic amide, Linolenic acid amide is mentioned, and stearic acid amide, oleic acid amide and erucic acid amide are preferable.

From the viewpoint of flexibility and low water absorption, the molded article of the present invention preferably has a morphology in which the carbon dioxide low-permeability resin (b) is dispersed in the thermoplastic resin (a). In the case of a cap liner, the opening torque can be easily controlled. The larger the dispersed particle shape is, the better from the viewpoint of low carbon dioxide permeability, and it is more preferable that the dispersed particle shape is flat and dispersed in a layer on the molding surface of the molded body.

As a specific dispersion structure, the average dispersed particle form of the carbon dioxide low-permeability resin has a length parallel to the surface of the molded body of 5 μm or more and a length perpendicular to the molded body of 2 μm or less. The structure that is flat and dispersed in layers suppresses the transmission of carbon dioxide, which is more effective.

For this purpose, the melt viscosity ratio of the low carbon dioxide permeable resin (b) to the thermoplastic resin (a) (the melt viscosity of the low carbon dioxide permeable resin (b) / the melt viscosity of the thermoplastic resin (a)) ) Is effective, and in the case of a cap liner, a cap liner formed by an in-shell mold method can be favorably obtained.

A feature of the molded article of the present invention is a mixed system of a thermoplastic resin and a carbon dioxide low-permeability resin, which suppresses the carbon dioxide permeability of the molded article.
Sheets, presses, blows, molded products made by injection molding, etc., especially when it is a cap liner, which prevents the inhibition of the flavor of the contents of the container, which is not present in conventional cap liners, and is excellent in long-term storage stability is there.

[0024]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist of the present invention.

The test and measurement methods used in the present invention are as follows.

<Method for Preparing Sample Cap> As a method for preparing a sample cap for a test described below, an in-shell molding method generally used for cap molding was adopted.
Specifically, the material was melt-extruded at a resin temperature of 200 ° C. using an extruder, a predetermined amount (about 300 mg) was hot-cut, and dropped into a 28 mmφ polypropylene cap shell. Immediately, the sample was pressurized and cooled with a pressing die, and adjusted to a liner shape to produce a sample cap.

<Test Bottle Preparation Method> A 500 ml PET bottle (manufactured by Toyo Seikan) has a carbon dioxide concentration of 50%.
To 0 ml, 500 ml of 4.2 volume carbon dioxide water was filled at 5 ° C., and using the prepared sample resin cap, tightening the cap was 15 kg-cm.
The test was carried out at a torque of 1.

<Confirmation of Dispersibility of Carbon Dioxide Low Permeability Resin> The center portion of the cap liner portion of the obtained sample cap is cut in a direction perpendicular to the plane of the cap liner.
The length and thickness of the carbon dioxide low-permeability resin existing at the center (0.1 × 0.1 mm) of the cut center were measured with an optical microscope (1000 magnification), and the average dispersed particle shape was confirmed. Was.

<Measurement of Cap Opening Torque> After storing the test bottle at 5 ° C. for one week, immediately, a cap opening torque measuring instrument (TNK-60B manufactured by Shinpo Kogyo Co., Ltd.)
, The opening torque of the cap wound around the test bottle was measured. The measured value of the cap opening torque is an average value of ten test bottles.

The proper value of the cap opening torque is 8
１５15 kg-cm.

<Carbon dioxide permeation test> JIS K712
According to 6-87 (Method A), a test was performed using a three-piece gas permeation tester manufactured by Toyo Seiki. The shape of the test piece was formed by pressing into a 150 x 150 x 0.4 mm flat plate,
The center portion was cut into a circle having a diameter of 70 mm to obtain a test piece. At present, the carbon dioxide permeation coefficient of a test piece prepared by the configuration of Comparative Example 1 which is generally used for carbonated beverages is set to 100, and compared with other cap liner materials.

Incidentally, it was confirmed that the dispersed particle shape of the carbon dioxide low-permeability resin of the test piece was equivalent to that of the cap liner.

Example 1 Thermoplastic resin (Ultra-linear low-density polyethylene manufactured by Tosoh Corporation: Lumitac 22-1; melt flow rate (J
IS K7210-76; 190 ° C, 2.16 kg load) 2 g / 10 min, density (JIS K6760-8)
1) 0.900 g / cm ³ , monodispersity 4.2, hereinafter PE
-1), and 70% by weight of a carbon dioxide low-permeability resin (ethylene-vinyl alcohol copolymer manufactured by Kuraray Co., Ltd .: Eval EP-G156A; carbon dioxide gas permeability coefficient: 2.8 × 10 ⁻¹⁸ mol × m / ( m ² × s × Pa), hereinafter referred to as EVOH-1) and 30% by weight.
0.3 parts by weight of erucic acid amide was added to parts by weight, and mixed for 15 minutes using a tumbler blender.
Melt-kneading and granulation at a resin temperature of 210 ° C. using a twin screw extruder manufactured by Toshiba Machine Co., Ltd. of 6 mm and 57 mmφ, using the obtained cap liner material, confirming carbon dioxide low permeability resin dispersibility, measuring cap opening torque And a carbon dioxide permeation test, and the test results are shown in Table 1.

Example 2 In Example 1, EVOH-1 was replaced with a carbon dioxide low-permeable resin (polyamide 6: UBE nylon 1011FB manufactured by Ube Industries, Ltd .; carbon dioxide gas permeability coefficient 5.2 × 10 5).
^-18 mol × m / (m ² × s × Pa), hereinafter referred to as PA6-1), and various tests were conducted as in Example 1.
Table 1 shows the test results.

Example 3 In Example 1, 90% by weight of PE-1 and EVOH-
Various tests were carried out in the same manner as in Example 1 except that the content was changed to 110% by weight. Table 1 shows the test results.

Example 4 In Example 1, 50% by weight of PE-1 and EVOH-
1 was changed to 50% by weight, and various tests were performed as in Example 1. Table 1 shows the test results.

Example 5 In Example 1, 40% by weight of a thermoplastic resin and PE-ethylene-vinyl acetate copolymer (manufactured by Tosoh Corporation: Ultracene 541, hereinafter referred to as EVA-1) were used.
Various tests were carried out in the same manner as in Example 1 except that the blend was changed to the weight%. Table 1 shows the test results.

Example 6 In Example 1, the thermoplastic resin was changed to a polypropylene resin (manufactured by Chisso Corporation: Chisso Polypro K1008; melt flow rate (JIS K7210-76; 230).
° C, 2.16 kg load) 11 g / 10 min, monodispersity 5.1, hereinafter referred to as PP-1) 7% by weight, hydrogenated styrene-ethylene-butylene-styrene block copolymer rubber (manufactured by Shell Japan K.K .: Clayton G1651;
MFR (JIS K7210-76; 230 ° C, 2.1
6 kg load) <0.1 g / 10 min, hereinafter SBC-1
Liquid paraffin (manufactured by Esso Oil Co., Ltd .: Christol J-322; viscosity (JIS K))
2283-83) 64 mm ² / S (40 ° C., hereinafter referred to as flow para-1) The blend was changed to 25% by weight, and various tests were carried out in the same manner as in Example 1. Table 1 shows the test results.

Example 7 In Example 1, the thermoplastic resin was changed to a linear low-density polyethylene (manufactured by Dow Chemical: Affinity PT145).
0; melt flow rate (JIS K7210-76;
190 ° C., 2.16 kg load) 7.5 g / 10 min,
Density (JIS K6760-81) 0.902 g / cm
³ , monodispersity 1.9, hereinafter referred to as PE-2)
Various tests were performed as in Example 1. Table 1 shows the test results.

COMPARATIVE EXAMPLE 1 0.3 part by weight of erucic acid amide was added to 100 parts by weight of PP-1 at 10% by weight, SBC-1 at 55% by weight and flow para-1 at 35% by weight. Various tests were performed on the cap liner material in the same manner as in Example 1. Table 1 shows the test results.

Comparative Example 2 In Example 1, EVOH-1 was replaced with PP-1 (carbon dioxide gas permeability coefficient 2.2 × 10 ⁻¹⁵ mol × m / (m ² × s).
× Pa)), and various tests were performed as in Example 1. Table 1 shows the test results.

Comparative Example 3 Various tests were carried out as in Example 1 except that 100% by weight of PE-1 and 0.3 part by weight of erucic acid amide were used. Table 1 shows the test results.

Comparative Example 4 In Example 1, 20% by weight of PE-1 and EVOH-
1 was changed to 80% by weight, and various tests were performed as in Example 1. Table 1 shows the test results.

[0044]

[Table 1]

[0045]

The molded article of the present invention has a characteristic of low carbon dioxide permeability, which is not found in conventionally known molded articles.
It is useful without losing the flavor of the contents of the container over a long period of time.

Claims (9)

[Claims] 1. A thermoplastic resin (a) of 30 to 99% by weight and a carbon dioxide gas permeability coefficient (JIS K7126-8)
7) is 1.0 × 10 ⁻¹⁷ mol × m / (m ² × s × Pa)
A molded product comprising the following carbon dioxide low permeable resin (b): 70 to 1% by weight. 2. The molding according to claim 1, wherein the thermoplastic resin (a) is at least one resin selected from the group consisting of polyolefin resins, polyolefin elastomers and styrene elastomers. body. 3. A polyolefin resin having a monodispersity (weight average molecular weight / number average molecular weight) of 1.5 to 3.0 in gel permeation chromatography of the thermoplastic resin (a). The molded article according to claim 1, wherein the molded article is provided. 4. The molded article according to claim 1, wherein the carbon dioxide low-permeability resin (b) is an ethylene-vinyl alcohol copolymer and / or a polyamide resin. 5. The average dispersed particle shape of the low carbon dioxide permeable resin (b) according to any one of claims 1 to 4 in the thermoplastic resin (a) has a length parallel to the surface of the molded body. 5 μm or more, the vertical length is also 2 μm or less, having a structure in which it is dispersed in the form of a flat layer on the surface of the molded body.
5. The molded article according to any one of 4. 6. The molded article according to claim 1, wherein the molded article is used as a cap liner. 7. A cap comprising the cap liner according to claim 6. 8. The cap according to claim 7, wherein the cap liner is formed by an in-shell molding method. 9. A packaging container comprising the molded product according to claim 1 or a cap.