JP2002265709A - Composition for cap liner material and cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for a cap liner material which has both heat resistance, flexibility and cap liner modability and can retain liner performance even after high temperature sterilization treatment. SOLUTION: The composition for a cap liner material comprising (a) 30-90 wt.% propylene based polymer having a melt flow rate of 0.1-100 g/10 min and a crystallization temperature of >=120 deg.C and (b) 70-10 wt.% polypropylene- ethylene/α-olefin copolymer having a melt flow rate of 1-50 g/10 min and a melting point of >=140 deg.C is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition having high heat resistance, high flexibility, and excellent cap liner moldability (particularly, in-shell moldability). More specifically, when the composition for a cap liner material is used as a cap liner for food (beverage) packaging containers by imparting flexibility and improving heat resistance, the contents (packaging containers) are sterilized at higher temperatures. Heat treatment becomes possible.

[0002] Due to such properties, the composition of the present invention can be subjected to high-temperature treatment in the process of sterilizing the contents (packaging containers) of foods (beverages) due to the superior heat resistance of the cap liner, Advantages such as shortening of the processing time are obtained, and there is an effect of preventing the content from being hindered by the temporal thermal history, which is effective.

[0003] Recently, retort sterilization (heat treatment at 100 to 130 ° C for 1 to 30 minutes) may be required for some of the diversified foods. It is.

[0004]

2. Description of the Related Art In general, as a composition used for a cap liner, a composition obtained by adding a hydrogenated styrene-conjugated diene block copolymer rubber and liquid paraffin to polyolefin (Japanese Patent Publication No. 6-88608). ) And simple polyethylene resins have been suitably used.

However, these compositions have low heat resistance, and the temperature of the heat treatment in the sterilization process of the contents (packaging containers) of foods (beverages) is about 95 ° C. even at a high temperature, so that a sufficient sterilizing effect can be obtained. The sterilization time was extended to make it work. However, there has been a concern about denaturation of contents, change in flavor, and the like due to long-term heat history.

As described above, currently used compositions for cap liner materials have the above-mentioned problem of low heat resistance, and are capable of sterilizing at higher temperatures. There is a need for a cap having a cap liner of the composition.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition for a cap liner material which is excellent in heat resistance, and which is excellent in flexibility and moldability of a cap liner, and a cap having a cap liner comprising the composition. Is to provide.

[0008]

The inventors of the present invention have conducted intensive studies and have found that a propylene-ethylene / α-olefin copolymer which is an elastomer component having a specific melt flow rate and a high melting point is used as a softening agent. The present inventors have found that a composition for a cap liner made of a combination with a propylene-based copolymer having a high crystallization temperature has both flexibility, moldability of a cap liner, and heat resistance, and have completed the present invention. That is, the present invention relates to a melt flow rate (JIS K7210-76; 230 ° C-2.
Propylene polymer (a) 3 having a load of 16 kg) of 0.1 to 100 g / 10 min and a crystallization temperature of 120 ° C. or higher
0 to 90% by weight, melt flow rate (JIS K72
10-76; 230 ° C.-2.16 kg load) 1-50
g / 10 min, polypropylene-ethylene / α-olefin copolymer (b) having a melting point of 140 ° C. or more
It is a composition for a cap liner material, characterized in that the composition is composed of% by weight.

The propylene polymer (A) used in the present invention has a melt flow rate (JIS K7210-
76; 230 ° C.-2.16 kg load) 0.1-100
g / 10 min, and the crystallization temperature is 120 ° C. or higher.

The propylene-based polymer (a) is prepared by melt flow rate (JIS K7210-76; 230 ° C.-2.
16 kg load, hereinafter referred to as MFR. ) Is 0.1 to 100
g / 10 min, preferably 1 to 50 g / 10 m
in. If the MFR is less than 0.1 g / 10 min, the extrusion load is excessively applied during the molding of the cap liner, resulting in poor molding. If the MFR exceeds 100 g / 10 min, the heat resistance and impact resistance are poor.

The propylene polymer (a) has a crystallization temperature of 120 ° C. or higher. When the crystallization temperature is lower than 120 ° C., the heat resistance is poor.

The crystallization temperature is measured by a scanning differential calorimeter (DSC) (manufactured by PerkinElmer, Inc .;
SC-7 ". 23 samples in DSC furnace
After melting at 0 ° C. for 5 minutes, a cooling rate of 10 ° C./min.
The temperature at the maximum peak position of the heat generation curve obtained by lowering the temperature to 0 ° C. and solidifying (crystallizing) was measured as the crystallization temperature.

The propylene polymer (a) can be obtained by a known production method, and can be produced by polymerization of propylene or copolymerization with a small amount (5% by weight or less) of α-olefin.

The crystallization temperature of the propylene-based polymer (a) is usually around 115 ° C., but the target crystallization temperature of 120 ° C. or higher can be achieved by adding a nucleating agent or the like. Specific examples of the nucleating agent include metal phosphates (Adeka Stab NA-11 manufactured by Asahi Denka) and metal carboxylate (Al-PTBBA manufactured by Shell).
% Is effective.

The polypropylene-ethylene / α-olefin copolymer (b) used in the present invention has an MFR of 1 to 5
0 g / 10 min, melting point 140 ° C. or higher. The polypropylene-ethylene / α-olefin copolymer (B) has M
FR is 1 to 50 g / 10 min, preferably 5
３０30 g / 10 min. The MFR of the polypropylene-ethylene / α-olefin copolymer (b) is 1 g / 10
If it is less than min, the extrusion load is excessively applied during the molding of the cap liner, resulting in poor molding. If it exceeds 50 g / 10 min, heat resistance and impact resistance are poor.

The polypropylene-ethylene / α-olefin copolymer (b) has a melting point of 140 ° C. or higher. When the melting point of the polypropylene-ethylene / α-olefin copolymer (b) is less than 140 ° C, heat resistance is poor.

The melting point is measured by a scanning differential calorimeter (DSC) (manufactured by PerkinElmer, Inc., apparatus name "DSC-
7 ". Once in the DSC furnace the sample is 230
Heat to ° C. After cooling to 30 ° C. and holding for 5 minutes, the temperature was raised to 230 ° C. at a heating rate of 10 ° C./min, and the temperature at the maximum peak position of the endothermic curve obtained by melting was measured as the melting point.

The α-olefin used in the polypropylene-ethylene / α-olefin copolymer (b) is, for example, propylene, 1-butene, 4-methyl-1
-Pentene, 3-methyl-1-butene, 1-pentene,
1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-
Tridecene, 1-tetradecene, 1-pentadecene, 1
-Hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, and the like, and one or more copolymers may be used. Among them, as the α-olefin, propylene and 1-butene are generally used. Among them, 1-butene improves the compatibility with the propylene-based polymer (a), and the material properties, especially high tensile strength , Low compression set, high ESCR and a large improvement effect, and the cap liner performance is also improved.

The polypropylene-ethylene / α-olefin copolymer (b) has a structure in which the ethylene / α-olefin copolymer component is finely dispersed in a matrix mainly composed of polypropylene, and has a melting point similar to that of polypropylene. It has the same flexibility as olefin-based elastomers, and is manufactured by Montelu Cataloy (C200F,
KS-359P, KS-357P, KS-084P, X
500F).

As the ethylene / α-olefin copolymer (b), one kind or a blend of two or more kinds can be used.

The composition for a cap liner material of the present invention comprises:
30 to 90% by weight of the propylene-based polymer (A),
Preferably 40 to 80% by weight, ethylene to α-olefin copolymer (b) 70 to 10% by weight, preferably 60
-20% by weight. If the propylene-based polymer (a) is less than 30% by weight, heat resistance is poor. If it exceeds 90% by weight, rigidity is too high and impact resistance is poor.

The composition for a cap liner material of the present invention comprises:
If necessary, thermoplastic resin, heat stabilizer, weather stabilizer,
Antiblocking agent, antistatic agent, slip agent, surfactant, antifogging agent, dropping agent, plasticizer, nucleating agent, pigment, dye, silica, titanium oxide, talc, mica, carbon, calcium carbonate, carbonic acid Inorganic or organic additives and fillers such as magnesium, metal stearate, wood powder, cork powder, and cellulose powder may be added as long as the object of the present invention is not impaired.

Of these, slip agents are often required to adjust the cap opening torque, and are generally used favorably. For example, higher fatty acid amides, 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 preferably used. , Caprylic amide, capric amide, lauric amide, myristic amide, palmitic amide, stearic amide, arachidic amide, behenic amide, oleic amide, erucic amide, linoleic amide, linolenic acid Amides are mentioned.

The composition for a cap liner material of the present invention comprises:
The propylene-based polymer (a) and the polypropylene-ethylene / α-olefin copolymer (b) are mixed by various methods known in the above range, for example, a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, and the like. Thereafter, a method of melt-kneading with a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like and granulating or pulverizing, or a method using a dry blend product or an auto feeder without prior melt-kneading is used.

In order to obtain a cap molded product, a cap having a cap liner composition as a cap liner is obtained by an in-shell molding method.

A feature of the composition for a cap liner material of the present invention is that a polypropylene-ethylene / α-olefin copolymer having a melt flow rate and a melting point limited to specific ranges is added to a propylene polymer having a high crystallization temperature. This is a composition for a cap liner material that has excellent cap liner moldability, high heat resistance and flexibility, which is not available in the conventional composition for a cap liner material.

Due to the above characteristics, a cap provided with a cap liner comprising the composition for a cap liner material of the present invention can be used for soft drinks, alcoholic drinks, coffee drinks, tea drinks, mineral water, dressings, grilled meats, sauces, and seasonings. It can be used as a cap for packaging containers for sauces, mayonnaise, salad oil, sesame oil and the like.

[0028]

EXAMPLES 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.

The test measurement method used in the present invention is as follows.

<Production method of composition for cap liner material> After blending each constituent raw material with a tumbler, L / D
Using a single screw extruder manufactured by Tanabe Plastics Machine Co., Ltd. of = 28 mm and 60 mmφ, kneading and granulation were performed at 230 ° C. to obtain a composition for a cap liner material.

<Evaluation of liner moldability> L / D = 25 m
m, 40 mmφ, using a single screw extruder manufactured by Tanabe Plastics Machine Co., Ltd., using a resin for a cap liner material at a resin temperature of 230 ° C., a screw rotation speed of 100 rpm, and a discharge amount of 15
8 kg / h.
Take out one strand from the hole of mmφ. The strand coming out of the die head is hot-cut with a rotary cutter so as to be 300 mg as it is. The hot-cut molten pellet is dropped on a 28 mmφ polypropylene cap, cooled under pressure, and adjusted to a cap liner shape. 1000 cap liners are molded and the success rate is measured. (Note that Nisso PP K1016 manufactured by Chisso was used as a raw material of the polypropylene cap.) <Drop test of water bottle> The following test was performed to compare the heat resistance and the impact resistance of the composition for the cap liner material. The method was implemented.

A 500 ml PET bottle was filled with hot water at 85 ° C., and a cap was tightened (tightening torque: 15 kg-cm) using a good cap prepared by evaluation of cap liner moldability. Thereafter, the mixture was placed in a retort sterilization pot, treated at 120 ° C for 20 minutes, and then allowed to cool to room temperature to obtain a test bottle.

[0033] Twenty dummy bottles (unretorted bottles) were placed in a cardboard carton case containing 24 bottles (4 bottles x 6 rows), and only four upper bottles contained test bottles.

The carton case was placed so that the four test bottles were at the upper stage, and the carton case was gradually tilted down by its own weight and dropped so that the top surface of the cap became an impact surface.

The test bottles were repeatedly dropped until the liquid leaked, and the number of drops of the test bottle was taken as the value of the number of drops, taken out of the carton case, replaced with a dummy bottle, and repeated until all the test bottles leaked. (However, the maximum number of drops was 30.) Example 1 As a composition for a cap liner material, a propylene-based resin (0.2% by weight of a nucleating agent ADK STAB NA-11 added to Nissopolypro K1016 manufactured by Nisso) was added. , MFR
5.0 g / 10 min, crystallization temperature 133 ° C, hereinafter PP
-1) and a polypropylene-ethylene / α-olefin copolymer (Catalloy KS manufactured by Montell)
-357P (polypropylene-ethylene-propylene copolymer) MFR 25 g / 10 min, melting point 142 ° C., hereinafter referred to as PER-1) 0.3 part by weight of erucamide was added to 100 parts by weight of 40% by weight. I got something. The composition was subjected to liner moldability evaluation and a water bottle drop test, and the test results are shown in Table 1.

Example 2 In Example 1, 80% by weight of PP-1 and PER-1
Was changed to 20% by weight, and a composition was obtained as in Example 1. Table 1 shows the test results.

Example 3 In Example 1, 40% by weight of PP-1 and PER-1
Was changed to 60% by weight, and a composition was obtained as in Example 1. Table 1 shows the test results.

Example 4 In Example 1, PP-1 was added to a propylene-based resin (Nisso-polypro K1800 manufactured by Chisso) with a nucleating agent ADK STAB N.
A-11 containing 0.2% by weight, MFR 21.0
g / 10 min, crystallization temperature 134 ° C., hereinafter referred to as PP-2), and a composition was obtained in the same manner as in Example 1. Table 1 shows the test results.

Example 5 In Example 1, PER-1 was replaced with a polypropylene-ethylene / α-olefin copolymer (Catalloy X manufactured by Montell).
500 (polypropylene-ethylene-butene copolymer), MFR 9g / 10min, melting point 162 ° C, below P
ER-2), and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 1 PP-1 20% by weight, hydrogenated styrene-ethylene-butylene block copolymer rubber (Clayton G1651 manufactured by Shell Japan, hereinafter referred to as SEBS) 40% by weight, liquid paraffin (Christole manufactured by Esso Oil Co., Ltd.) J-2
62; viscosity (JIS K2283-83) 51 mm2 /
S (40 ° C., hereinafter referred to as “flow para”) was added in an amount of 40 parts by weight and erucic acid amide was added in an amount of 0.3 part by weight. Table 1 shows the test results.

Comparative Example 2 Erucamide was added to 100 parts by weight of PP-1 in 0.1 part by weight.
3 parts by weight were added, and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 3 In Example 1, PP-1 was replaced with a propylene resin (Nisso polypro K1016 manufactured by Chisso, MFR 5.0 g / 10 g).
min, the crystallization temperature was changed to 114 ° C., hereinafter referred to as PP-3), and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 4 In Example 1, PER-1 was replaced with a polypropylene-ethylene / α-olefin copolymer (Catalloy 5 manufactured by Montell).
C30F (polypropylene-ethylene-propylene copolymer), MFR 5.5 g / 10 min, melting point 130 ° C,
(Hereinafter referred to as PER-3), and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 5 In Example 1, 15% by weight of PP-1 and PER-1
Was changed to 85% by weight, and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 6 In Example 1, PER-1 was replaced with a polypropylene-ethylene / α-olefin copolymer (Montal's Cataloy K
S-353P (polypropylene-ethylene-propylene copolymer), MFR 0.45 g / 10 min, melting point 14
The temperature was changed to 2 ° C., hereinafter referred to as PER-4), and a composition was obtained as in Example 1. Table 1 shows the test results.

[0046]

[Table 1]

EFFECT OF THE INVENTION The composition for a cap liner material of the present invention does not exist in a conventionally known composition for a cap liner material,
It has both heat resistance, flexibility, and cap liner moldability, and is useful because it retains liner performance even after high-temperature sterilization.

Claims (4)

[Claims] 1. A melt flow rate (JIS K7210)
−76; 230 ° C.-2.16 kg load) 0.1 to 10
0 g / 10 min, 30 to 90% by weight of a propylene-based polymer (a) having a crystallization temperature of 120 ° C. or higher, and a melt flow rate (JIS K7210-76; 230 ° C.-2.16)
A composition for a cap liner material comprising 70 to 10% by weight of a polypropylene-ethylene / α-olefin copolymer (b) having a weight (kg load) of 1 to 50 g / 10 min and a melting point of 140 ° C. or higher. 2. The composition for a cap liner material according to claim 1, wherein the α-olefin component of the polypropylene-ethylene / α-olefin copolymer (b) is butene. 3. A cap having a cap liner comprising the composition for a cap liner material according to claim 1. 4. A packaging container having the cap according to claim 3.