JP2003205962A - Composition for cap liner, and cap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a cap liner which is heat resistant so as to be adaptable to a thermal-sterilizing step at a high temperature, and flexible, and a cap having the cap liner formed of the composition. <P>SOLUTION: The composition for the cap liner consists of, by weight, 20-89% propylene polymer (a) in which the melt-flow rate in accordance with JIS K7210-76 (230°C×2.16 kgf) is 0.1-100 g/10 min, and the crystallization temperature measured by a scanning differential thermal calorimeter is ≥120°C, 10-50% hydrogenated styrene conjugate diene block copolymer (b) in which the viscosity of the solution measured with 5% toluene solution (30°C) is 80-500 mPa s, and the styrene content is 25-40%, and 1-30% liquid paraffin (c). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition having high heat resistance and flexibility. Specifically, when used as a cap liner for a food (beverage) packaging container by imparting flexibility to the composition for a cap liner material and improving heat resistance,
It enables sterilization heat treatment of contents (packaging container) at a higher temperature.

Due to such characteristics, the composition of the present invention can be subjected to high temperature treatment in the sterilization process of the contents (packaging container) of foods (beverages) due to the superior heat resistance of the cap liner, Advantages such as shortening of processing time are obtained, and there is an effect of preventing the flavor change of the contents caused by the thermal history over time, which is effective.

Recently, some diversified foods may require retort sterilization (heat treatment at 100 to 130 ° C. for 1 to 30 minutes), and this treatment can be used and is effective. Is.

[0004]

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

However, these compositions have low heat resistance, and the heat treatment temperature in the process of sterilizing the contents (packaging container) of foods (beverages) is about 95 ° C. even at high temperatures, and a sufficient sterilizing effect is obtained. The sterilization time was extended in order to bring out the effect. However, there has been concern about denaturation of contents, change in flavor, etc. due to a long heat history.

As described above, the composition for a cap liner material currently used has the above-mentioned problem of low heat resistance, and the composition for a cap liner material which can be sterilized at a higher temperature and There is a need for a cap having a cap liner composed of the composition.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to have heat resistance capable of supporting a heat sterilization process at high temperatures, and
It is an object of the present invention to provide a cap liner material composition having high flexibility and a cap having a cap liner comprising the composition.

[0008]

Therefore, as a result of intensive studies by the present inventors, a specific solution viscosity as a flexibility-imparting material,
A composition for a capliner material comprising a combination of a hydrogenated styrene-conjugated diene block copolymer, which is an elastomer component having a styrene content, and a propylene-based copolymer having a specific crystallization temperature, and liquid paraffin,
They have found that they have both flexibility and high heat resistance, and have completed the present invention. That is, the present invention is based on JIS K72.
The melt flow rate according to 10-76 (230 ° C. × 2.16 kg load) is 0.1 to 100 g / 10 min, and the crystallization temperature measured using a scanning differential calorimeter is 1.
Propylene-based polymer (a) 20 to 89 having a temperature of 20 ° C. or higher
Wt%, 5 wt% -a hydrogenated styrene-conjugated diene block copolymer having a solution viscosity of 80 to 500 mPa · s measured with a toluene solution (30 ° C.) and a styrene content of 25 to 40 wt% ) 10 to 50% by weight and 1 to 30% by weight of liquid paraffin (C) are composition for a cap liner material.

The present invention will be described in detail below.

The propylene polymer (a) used in the present invention is JIS K7210-76 (230 ° C. × 2.
Melt flow rate (hereinafter referred to as 16 kg load)
MFR) is 0.1 to 100 g / 10 min, and the crystallization temperature measured using a scanning differential calorimeter is 12
It is 0 ° C or higher.

The propylene polymer (a) has an MFR of 0.1 to 100 g / 10 min, preferably 1 to
It is 50 g / 10 min. MFR is 0.1g / 10m
If it is less than in, extrusion load is excessively applied during molding of the cap liner, resulting in poor molding, and if it exceeds 100 g / 10 min, heat resistance and impact resistance are poor.

Further, the propylene polymer (a) has a crystallization temperature of 120 ° C. or higher measured by a scanning differential calorimeter, and a crystallization temperature of less than 120 ° C. results in poor heat resistance.

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 such a propylene-based polymer is around 115 ° C. at the highest, but the crystallization temperature can be 120 ° C. or higher by highly crystallizing it by adding a nucleating agent or the like.

Specific nucleating agents include metal phosphates (Adeka Stab NA-11 manufactured by Asahi Denka Co., Ltd.), carboxylic acid metal salts (Al-PTBBA manufactured by Shell), and the like.
The effect is obtained with the addition of 01 to 1 wt%.

The crystallization temperature is measured by a scanning differential calorimeter (DSC) (manufactured by Perkin Elmer Co., Ltd., device name: "D").
SC-7 ". 23 samples in DSC furnace
Melt at 0 ° C for 5 minutes, then cool at 3 ° C at 10 ° C / min.
The temperature at the maximum peak position of the exothermic curve obtained by lowering to 0 ° C. and solidifying (crystallization) was measured as the crystallization temperature.

The hydrogenated styrene-conjugated diene block copolymer (B) used in the present invention has a solution viscosity of 80 to 500 mPa measured in a 5 wt% toluene solution (30 ° C.).
-S, and the styrene content is 25 to 40% by weight. Hydrogenated styrene-conjugated diene block copolymer (b)
Has a solution viscosity of 80 to 500 mPa · s measured with a 5 wt% -toluene solution (30 ° C.), preferably 1
It is from 00 to 400 mPa · s. Solution viscosity is 80mPa
・ If it is less than s, the heat resistance of the cap liner is insufficient, and 5
If it exceeds 00 mPa · s, extrusion load will be applied too much during molding of the cap liner, resulting in defective molding.

The solution viscosity measured with a 5 wt% -toluene solution (30 ° C.) was measured using a B type viscometer.
It was measured. Weigh 60 g of sample and 540 g of toluene into a sample bottle (capacity 1000 ml glass cylindrical bottle with screw stopper (capacity 1000 ml, mouth inner diameter 60 mm)), seal the sample bottle, and shake until the sample is completely dissolved. Stir with. Next, the sample bottle is put in a constant temperature water bath kept at 30 ° C, and when it reaches 30 ° C, a rotor and a guard are attached, and the sample bottle is immersed in the solution up to the position of the immersion mark of the rotor.
Start the viscometer and read the scale of the viscometer after the indicated value stabilizes.

The hydrogenated styrene-conjugated diene block copolymer (b) has a styrene content of 25 to 40% by weight, preferably 26 to 35% by weight. If the styrene content is less than 25% by weight, the heat resistance of the cap liner will be insufficient, and if it exceeds 40% by weight, the flexibility of the cap liner will be impaired.

Specific examples of the hydrogenated styrene-conjugated diene block copolymer (b) are as follows: hydrogenated styrene-butadiene diblock copolymer, hydrogenated styrene-butadiene-styrene triblock copolymer, Hydrogenated styrene-isoprene diblock copolymer, hydrogenated styrene-isoprene-styrene triblock copolymer, hydrogenated styrene-isoprene-butadiene diblock copolymer, hydrogenated styrene-isoprene-butadiene-styrene triblock copolymer Examples thereof include a combination, and one kind of these or a blend of two or more kinds can be used. Among these, hydrogenated styrene-isoprene-butadiene-styrene triblock copolymer in which the conjugated diene block is a mixture of isoprene and butadiene is excellent in material strength,
More useful.

The hydrogenated styrene-conjugated diene block copolymer (b) is, for example, Kraton G1651 (hydrogenated styrene-butadiene-styrene triblock copolymer type) manufactured by Kraton Polymer Japan Co., Ltd., Septon 4055 manufactured by Kuraray Co., Ltd. (Hydrogenated styrene-isoprene-butadiene-styrene triblock copolymer type), 4077 (hydrogenated styrene-isoprene-butadiene-styrene triblock copolymer type), and the like are available.

Liquid paraffin used in the present invention (c)
May be commercially available in consideration of food additives, and examples thereof include trade name Cristol (Esso Oil Co., Ltd.) and trade name Moresco White (Matsumura Oil Research Co., Ltd.).

The composition for a cap liner material of the present invention is
20 to 89% by weight of the propylene polymer (a),
Preferably 30 to 80% by weight, hydrogenated styrene-conjugated diene block copolymer (B) is 10 to 50% by weight, preferably 15 to 45% by weight and liquid paraffin (C) is 1 to
It is composed of 30% by weight, preferably 5 to 25% by weight. If the propylene polymer (a) is less than 20% by weight, the heat resistance is poor, and if it exceeds 89% by weight, the rigidity is too high and the flexibility is poor. When the hydrogenated styrene-conjugated diene block copolymer (b) is less than 10% by weight, flexibility is poor,
If it exceeds 50% by weight, the moldability of the cap liner is poor due to insufficient fluidity. If the liquid paraffin (C) is less than 1% by weight, the moldability of the cap liner is poor due to insufficient fluidity, and if it exceeds 30% by weight, the heat resistance is poor.

The composition for a cap liner material of the present invention is
If necessary, thermoplastic resin, heat resistance stabilizer, weather resistance stabilizer,
Antiblocking agent, antistatic agent, slip agent, surfactant, antifogging agent, drip agent, plasticizer, nucleating agent, pigment, dye, silica, titanium oxide, talc, mica, carbon,
Inorganic or organic additives such as calcium carbonate, magnesium carbonate, metal stearate, wood powder, cork powder, cellulose powder, and silicone oil, and fillers may be added within a range that does not impair the object of the present invention.

Among them, the slip agent is often necessary for adjusting the cap opening torque and is generally preferably used. For example, higher fatty acid amide, higher fatty acid, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, higher alcohol fatty acid ester, ethylene bis higher fatty acid amide, etc. are used, and preferably higher fatty acid amide is used. Shows, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidonic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid Examples include amides.

The composition for a cap liner material of the present invention is
The propylene-based polymer (a), the hydrogenated styrene-conjugated diene block copolymer (b) and the liquid paraffin (c) are various methods known in the above range, for example, Henschel mixer, V-blender, ribbon. Blender,
After mixing with a tumbler blender, etc., melt kneading with a single-screw extruder, twin-screw extruder, kneader, Banbury mixer, etc., and granulating or pulverizing, or a method using a dry blend product or an auto feeder without melt kneading in advance. Is used.

In order to obtain a cap molded article, a cap is obtained by mounting the composition for a cap liner material as a cap liner by the in-shell molding method.

The characteristics of the composition for a cap liner material of the present invention are a propylene-based polymer having a high crystallization temperature, a hydrogenated styrene-conjugated diene block copolymer in which the melt viscosity and the styrene content are limited to specific ranges, and It is a composition for a cap liner material, which has high heat resistance and flexibility, which are not present in conventional compositions for a cap liner material, by adding liquid paraffin.

Due to the above characteristics, the cap liner made of the composition for a cap liner material of the present invention can be attached to a resin cap or a metal cap, particularly at 100 ° C.
As described above, it can be applied to a glass or metal bottle that can be heat-sterilized (retort) and is useful.

The cap equipped with the cap liner of the present invention is used for packaging containers for soft drinks, alcoholic drinks, coffee drinks, tea drinks, mineral water, dressings, sauces for seasoned meat, seasoning sauces, mayonnaise, salad oil, sesame oil, etc. Can be used as a cap.

[0030]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

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

<Method for producing composition for cap liner material> After blending each constituent raw material with a tumbler, a twin screw extruder of L / D = 36 mm and 57 mmφ adjusted to a resin temperature of 230 ° C. (manufactured by Toshiba Machine Co., Ltd.) , Trade name TEM-50
Melt kneading and granulation were carried out in B) to obtain a composition for a cap liner material.

<Measurement of compression set> The compression set is measured in accordance with JIS K 6301-75, 5
Using a press die of 0 × 150 × 12.5 mm, press at a press temperature of 200 ° C. and a press pressure of 75 kg / cm ² ,
A flat plate sample was prepared. This flat plate sample has a diameter of 29
The thickness of the test piece (the original thickness of the test piece)
Was measured to obtain a compression set test piece. JIS K
The test piece was compressed to 9.52 mm in the thickness direction using the compression fixing device specified in 6301-75, and the device that fixed the test piece was heated at 120 ° C. for 22 hours. Then, the compression is released, and the test piece is allowed to stand at 23 ° C. for 30 minutes,
The thickness of the test piece after compression (thickness after compression) was measured. Then, the compression set was determined by the following equation.

Compression set (%) = (original thickness of test piece−thickness after compression) × 100 ÷ (original thickness of test piece−9.52) <Method for producing sample cap> As a method for producing the sample cap, a cap is used. The in-shell molding method used for molding was adopted. Specifically, the composition for a cap liner material is melt extruded by an extruder (manufactured by Tanabe Plastics Co., Ltd., trade name V-20) adjusted to a resin temperature of 230 ° C., and extruded through a die hole having a diameter of 7 mm. Hot-cut the strands to 300 mg, 28
A sample cap was prepared by dropping it into the shell of a mmφ aluminum cap and immediately adjusting it to a cap liner shape with a pressing die.

<Method for producing sample bottle> 500 ml
500 ml of orange juice (30% by weight orange juice concentration water) in an aluminum bottle (made by Daiwa Seikansha Co., Ltd.)
Filled and fitted with test cap sample. afterwards,
It was put in a retort kettle and heated for 10 minutes using hot water adjusted to 120 ° C. with pressure steam to obtain a sample bottle.

<Drop Test of Sample Bottle> As a test for comparing the flexibility and heat resistance of the cap liner, the following test method was carried out.

Twenty-five dummy bottles (similarly 500 ml aluminum bottles with 500 ml of water and caps tightened) were placed in a cardboard carton case containing 30 pieces (5 pieces × 6 steps) in one box. , Only the upper 5 bottles were filled with sample bottles.

The carton case was placed so that the five sample bottles were in the upper stage, and the carton case was gradually tilted by its own weight so that the top surface of the cap became the impact surface, and dropped onto a flat concrete surface.

Dropping is repeated until a sealing failure such as liquid leakage occurs, and the sample bottle with the sealing failure is taken as the drop count value, taken out from the carton case and replaced with a dummy bottle, and all the sample bottles are sealed. Repeated until bad. However, in actual use, there is no problem if the number of drops is 30 or more. Maximum number of drops 3
It was 0 times.

Example 1 As a composition for a cap liner material, a propylene resin (manufactured by Chisso Corporation, Chisso Polypro K1140, kneaded with 0.2% by weight of a nucleating agent ADEKA STAB NA-11, melt flow rate (JIS K7210). 230
C. × 2.16 kg load) 40 g / 10 min, crystallization temperature 133 ° C., 40% by weight of PP-1), hydrogenated styrene-conjugated diene block copolymer (Kuraray Co., Ltd., trade name Septon 4055 (water) Styrene-isoprene-butadiene-styrene triblock copolymer, solution viscosity 90 mPa · s (5 wt% -toluene solution, 30
C), styrene content 30% by weight, hereinafter referred to as SBC-1) 40% by weight, and liquid paraffin (produced by Esso Sekiyu KK, trade name Cristol J-262, hereinafter referred to as flow para-1) 20% by weight. Then, 0.5 part by weight of erucic acid amide was added to 100 parts by weight of these in total to obtain a composition for a cap liner material. Using this composition for a cap liner material, compression set measurement and sample bottle drop test were performed, and the test results are shown in Table 1.

[0041]

[Table 1] Example 2 In Example 1, 60% by weight of PP-1 and SBC-1 were used.
Was changed to 30% by weight and flow Para-1 was changed to 10% by weight to obtain a composition for a cap liner material in the same manner as in Example 1. The results of these tests are shown in Table 1.

Example 3 In Example 1, SBC-1 was hydrogenated styrene-conjugated diene block copolymer (Kuraray Co., Ltd., trade name Septon 4077 (hydrogenated styrene-isoprene butadiene-styrene triblock copolymer). , Solution viscosity 300mP
a · s (5 wt% -toluene solution, 30 ° C.), styrene content 30 wt%, hereinafter referred to as SBC-2),
A composition for a cap liner material was obtained in the same manner as in Example 1.
The results of these tests are shown in Table 1.

Example 4 In Example 3, 60% by weight of PP-1 and SBC-2 were used.
Was changed to 30% by weight and flow Para-1 was changed to 10% by weight to obtain a composition for a cap liner material in the same manner as in Example 1. The results of these tests are shown in Table 1.

Comparative Example 1 In Example 1, PP-1 was mixed with propylene resin (manufactured by Chisso Corporation, Chisso Polypro K1140, melt flow rate (JIS K7210; 230 ° C. × 2.16 k).
g load) 40 g / 10 min, crystallization temperature 114 ° C., hereinafter referred to as PP-2), and a cap liner composition was obtained in the same manner as in Example 1. The results of these tests are shown in Table 1.
It was shown to.

Comparative Example 2 In Example 1, SBC-1 was hydrogenated styrene-conjugated diene block copolymer (Kuraray Co., Ltd., trade name Septon 4044 (hydrogenated styrene-isoprene butadiene-styrene triblock copolymer). , Solution viscosity 22 mPa
* S (5 wt% -toluene solution, 30 ° C), styrene content 32 wt%, hereafter referred to as SBC-3), and a composition for a cap liner material was obtained in the same manner as in Example 1. The results of these tests are shown in Table 1.

Comparative Example 3 In Example 1, PP-1 was used as high density polyethylene (manufactured by Tosoh Corporation, trade name Nipolon Hard 1200, MF).
R (JIS K7210; 190 ° C. × 2.16 kg load) 21 g / 10 min, density 0.952 g / cm ³ ,
(Hereinafter referred to as HD-1), and a composition for a cap liner material was obtained in the same manner as in Example 1. The results of these tests are shown in Table 1.

Comparative Example 4 In Example 1, 90% by weight of PP-1 and SBC-1 were used.
Was changed to 6 wt% and flow Para-1 was changed to 4 wt% to obtain a composition for a cap liner material in the same manner as in Example 1. The results of these tests are shown in Table 1.

Comparative Example 5 In Example 1, 10% by weight of PP-1 and SBC-1 were used.
Was changed to 60% by weight and flow Para-1 to 40% by weight, and a composition for a cap liner material was obtained in the same manner as in Example 1. The results of these tests are shown in Table 1.

[0049]

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

Claims (6)

[Claims] 1. JIS K7210-76 (230 ° C. ×
A propylene-based polymer (a) 20 to 89 having a melt flow rate of 0.1 to 100 g / 10 min based on a (2.16 kg load) and a crystallization temperature of 120 ° C. or higher measured using a scanning differential calorimeter. % By weight, 5% by weight-solution viscosity measured with toluene solution (30 ° C.) is 80-50
The hydrogenated styrene-conjugated diene block copolymer (b) having a styrene content of 25 to 40% by weight and the liquid paraffin (c) of 1 to 30% by weight. A composition for a cap liner material, comprising: 2. A hydrogenated styrene-conjugated diene block copolymer (b) is a hydrogenated styrene-isoprene-butadiene-polymer.
The composition for a cap liner material according to claim 1, which is a styrene triblock copolymer. 3. A cap liner comprising the composition for a cap liner material according to claim 1 or 2. 4. A cap to which the cap liner according to claim 3 is attached. 5. A container equipped with the cap according to claim 4. 6. A container is filled with food or beverage, and 1
The container according to claim 5, which is heat-sterilized at a temperature of 00 ° C or higher.