JP2000281117A - Cap liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft drink having a heat sterilization process after hot filling of contents and filling and sealing among soft drinks due to excellent flexibility and heat-resistant rubber elasticity of a styrene-based thermoplastic elastomer. In addition, the present invention also provides a cap liner used for sealing a synthetic resin cap excellent in hygiene without impairing the hermetic sealability even in contents such as carbonated beverages under internal pressure. SOLUTION: This liner is used to be joined to the inside of the top surface of a synthetic resin screw-type cap, and the average thickness of the top surface contact liner portion that comes into contact with the top surface of the tip of the container mouth is 0.3 to 1.3. 5 mm, outer periphery near the tip of the container mouth and / or
Or, the average height of the liner rising portion in contact with the inner peripheral portion is 0.3 to 2 mm from the thickness of the top surface contact liner portion.
High, and the average thickness of the liner rising part is
3 to 1.5 mm, the hardness of the liner (JIS-
A) wherein A) is in the range of 50 to 95 and the composition of the liner is a specific composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liner of a synthetic resin cap used for a soft drink container or the like,
Excellent softness of styrene-based thermoplastic elastomers, soft drinks with a heat sterilization process after hot filling and filling and sealing of the contents among soft drinks due to heat-resistant rubber elasticity,
In addition, even for contents such as carbonated beverages that are subject to internal pressure, the sealing property is not impaired, an abnormal increase in opening torque is prevented, opening is easy in actual use, and furthermore, the container opening and closing is performed. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cap liner used for sealing a synthetic resin cap with improved hygiene in which liner wear during contact friction with a portion is improved and elution from the liner material is prevented.

[0002]

2. Description of the Related Art In recent years, PET bottles have been remarkably increasing as containers for soft drinks and the like. Aluminum caps were initially used as cap materials for containers, but recently synthetic resins such as polypropylene have been used. The use of caps made of plastic is being promoted. This is because in the case of recycling PET bottle containers with aluminum caps, it is difficult to separate specific gravity through water with conventional PET materials and aluminum materials, whereas PET materials and olefin-based synthetic materials are difficult to separate. The combination of resin caps is due to the ease of specific gravity separation. This PET
As a liner material for the cap of the container, an olefin-based resin such as low-density polyethylene has been mainly used for the aluminum cap at the beginning, but with the movement of the synthetic resin-based cap, a styrene-based resin has been used. Elastomer liner materials are used in some fields, such as soft drinks, which have a heat sterilization process after hot filling or filling and sealing of soft drinks, and synthetic resin caps for contents containers such as carbonated drinks with internal pressure. It is being used for liners.

[0003] This material change is due in part to the structure of a synthetic resin cap and an aluminum cap,
Material differences can be mentioned. That is, in the conventional aluminum cap, the oak treatment of the outer peripheral edge corresponding to the cap top liner is usually performed, but in the case of the synthetic resin cap, the oak treatment is performed due to the characteristics of the material. It cannot be done like aluminum caps. Therefore, when conventional olefin resin such as low-density polyethylene is used as it is as a liner material for a cap made of synthetic resin, sealing of contents that require high-temperature filling and heat sterilization and contents such as carbonated drinking water that requires internal pressure. In the sealing properties, there are problems such as leakage from the point of plastic deformation and permanent distortion, and there is also a problem in the leakage property against impact during transportation. A liner material made of an elastomer such as styrene, which has excellent properties, has been mainly used.

Japanese Patent Application Laid-Open No. 2-57569 discloses a heat-resistant liner material that can withstand hot filling of contents and heat sterilization after filling and sealing, as well as heat deformation and heat shrinkage. As a heat-resistant liner material in which leaks are effectively eliminated, 10 to 60% by weight of a hydrogenated styrene / butadiene block copolymer, 20 to 8 liquid paraffins
A composition comprising 0% by weight and 5 to 60% by weight of a propylene-based resin is disclosed. However, in the above-mentioned compounding system, since the amount of liquid paraffin, which is a compound component greatly affecting moldability, has a large range of 20 to 80% by weight, the moldability is high where the amount of liquid paraffin is large. Although good, the following wax float problem occurred.

[0005] That is, in the case of a cap liner using a composition containing a large amount of liquid paraffin, the container is filled with a liquid, the cap is wound up, sealed, and then commercialized. If left unattended in the environment, oily substances, which are considered to be liquid paraffin, separate from the liner material, and may float in droplets on the surface of the content liquid or form an oil film (hereinafter referred to as wax float). there were. Conversely, a composition containing a small amount of liquid paraffin rarely causes wax float, but has a problem in molding processability due to insufficient fluidity and poor fusion between materials. Further, this composition has good compression set over a wide range from low to high temperatures, and is excellent in hermetic sealability.However, this good compression set increases the torque value at the time of opening use. It is presumed that a large amount of lubricant is required in order to lower the torque value at the time of unsealing use, and as a result, there is a case where the added lubricant has a problem of bleeding with time.

Japanese Patent Application Laid-Open No. 7-76360 discloses that the disadvantages of the prior art are solved, in that the contents are resistant to hot filling and heat sterilization after filling and sealing, leakage is effectively eliminated, and A wax float improved heat resistant liner composition is disclosed. In other words, with respect to such moldability and wax float problem, the amount of liquid paraffin is reduced by making the hydrogenated styrene / butadiene block copolymer in the composition a low molecular weight type having good moldability. It was done. However, in such a blended system, even if the thermoplastic elastomer has relatively high heat resistance, the hydrogenated styrene / butadiene block copolymer in the composition has a low molecular weight. The compression set and the permanent elongation in the high temperature range, which are presumed to be caused, were large, and the material strength was low. For this reason, an increase in torque at the time of opening the use, which is considered to be caused by the deformation of the liner and the phenomenon of fusing to the bottle main body, was observed depending on the processing conditions such as high-temperature filling and heat sterilization.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liner for a synthetic resin cap which solves the above problems. In detail, there is no problem in the formability of the liner, and there is no liquid leakage even after hot filling and heat sterilization treatment of the internal solution such as a soft drink, and there is no internal pressure drop in the internal solution such as a carbonated beverage. It has excellent hermetic sealing properties, is easy to open in actual use, improves wear of the liner material due to contact friction with the container opening when opening and closing the cap, and wax caused by liquid paraffin in the liner material An object of the present invention is to provide a liner for a cap made of a synthetic resin which is excellent in hygiene and prevents bleeding over time due to additives such as a float and a lubricant.

[0008]

The liner of the present invention is a liner which is used by being joined to the inside of the top surface of a screw-in cap made of synthetic resin, the top surface contact liner being in contact with the top surface of the top end of the container mouth. Average thickness of the part is 0.3-1.5m
m, the average height of the liner rising portion in contact with the outer peripheral portion and / or the inner peripheral portion near the tip of the container mouth is 0.3 to 2 mm higher than the thickness of the top surface contact liner portion, and the average of the liner rising portion The thickness is 0.3 to 1.5 mm, and the hardness (JIS-A) of the liner material is 50 to
95, wherein the composition of the liner is as follows:
A cap liner comprising a component, a component (B), and a component (C). Component (A): a hydrogenated product of a styrene / conjugated diene block copolymer, wherein the conjugated diene is isoprene alone or a mixture of isoprene and butadiene (mixing weight ratio of isoprene and butadiene 100/0 to 1/99). The hydrogenated product of a certain copolymer is 45 to 70% by weight based on the total amount of (A) and (B). Component (B): The total amount of rubber softener and / or liquid paraffin in (A) and (B) (C) component: melt flow rate (230 ° C., 2.16%)
(kg load) of 0.1 to 100 g / 10 min of crystalline polypropylene resin and / or melt flow rate (190
C., 2.16 kg load) with a polyethylene resin having a density of 0.1 to 50 g / 10 min and a density of 0.940 g / cm < ³ > or more based on 100 parts by weight of the total amount of (A) and (B).
0 parts by weight

The inventor of the present invention has provided a liner having the above-mentioned characteristics,
Good moldability, hot filling of inner solution such as soft drinks,
Even after heat sterilization treatment, there is no leakage of the internal solution without impairing the heat-resistant rubber elasticity, and it has a good hermetic seal with no internal pressure drop even in internal solutions such as carbonated beverages, and it is opened at the time of actual use That the liner wear is improved when the cap is repeatedly opened and closed, and that the softener such as liquid paraffin is eluted, and that the lubricant is effective in preventing bleeding. They have found and completed the invention.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [A] Liner shape The liner according to the present invention is hermetically sealed in a cap shell using a known liner molding method. After forming into a relatively thin sheet, it is punched into a diameter that matches the shape of the cap, then inserted into the cap and bonded, or by inserting the pre-formed cap into the mold by the insert double injection method, and then the liner. A method in which a material is melt-injected into the inner side of the top surface of the cap, or an in-shell molding method in which a certain amount of extruded molten resin is dropped inside the cap and embossed under cooling to form a liner shape. be able to. Among them, the in-shell molding method is preferable.

As shown in FIGS. 1 and 2, a liner according to the present invention has a cap 7 made of synthetic resin such as polypropylene.
The average thickness of the top surface contact liner portion 1 that contacts the top surface 4 of the container mouth is 0.3 to 1.5 mm, and the outer peripheral portion 5 of the container mouth and / or The average height of the rising liner portions 2 and 3 that are in contact with the inner peripheral portion 6 is 0.3 to 2 times greater than the thickness of the top surface contact liner portion 1.
mm higher. In addition, the average thickness of the liner rising portions 2 and 3 is 0.3 to 1.5 mm. The average thickness of the top surface contact liner portion 1 that contacts the top surface 4 of the tip of the container mouth is 0.3 to 5 mm, preferably 0.4.
１1.0 mm. If the average thickness is less than 0.3, it is too thin, so that a sufficient rubber-like elastic effect cannot be obtained, so that the hermetically sealing property of the content liquid becomes insufficient. Further, a problem of poor fusion with the cap shell occurs, and the material strength is also weakened. On the other hand, if the thickness exceeds 1.5 mm, it is too thick, which is economically disadvantageous such as poor bubble generation, an increase in molding cycle time, and an increase in price.

The average height of the rising liner portions 2, 3 in contact with the outer peripheral portion 5 and / or the inner peripheral portion 6 of the container mouth is 0.3 to 2 mm higher than the thickness of the top surface contact liner portion 1.
Preferably, it is 0.4 to 1.5 mm. Average height is 0.
If it is less than 3 mm, a sufficient rubber-like elastic effect cannot be obtained.
The hermetic sealing of the content liquid becomes insufficient, and the material strength is also reduced. Conversely, if the thickness exceeds 2.0 mm, the sealing performance is sufficient, but the opening torque of the cap is increased due to frictional resistance, resulting in poor opening performance and abrasion. The average thickness of the liner rising portions 2 and 3 is 0.3 to 1.3.
5 mm, preferably 0.4 to 1.3 mm. If the thickness is less than 0.3 mm, a sufficient rubber-like elastic effect cannot be obtained, so that the hermetic sealing property of the content liquid becomes insufficient and the material strength is also reduced. On the other hand, if the thickness exceeds 1.5 mm, the sealing property is sufficient, but the opening torque of the cap is increased, the opening property is deteriorated, and abrasion occurs. The rising liner portions 2 and 3 that come into contact with the outer peripheral portion 5 and the inner peripheral portion 6 of the container mouth may be only one of the liner portions 2 and 3 that are in contact with the outer peripheral portion 5 or the inner peripheral portion 6.

[B] Elastomer composition for liner (1) Constituent components (essential components) (A) Hydrogenated product of styrene / conjugated diene block copolymer [Component (A)] Elastomer composition for cap liner of the present invention Examples of the hydrogenated product of the styrene / conjugated diene block copolymer (A) used in the above include:
The conjugated diene is a polymer block composed of isoprene alone or a mixture of isoprene and butadiene. Specifically, a hydrogenated product of styrene / isoprene / styrene block copolymer (hereinafter simply referred to as “hydrogenated SI- S ") or a hydrogenated product of a styrene- (isoprene / butadiene) -styrene block copolymer (hereinafter sometimes simply referred to as" hydrogenated S-BI-S "). ). Among them, the conjugated diene is hydrogenated S which is a mixture of isoprene and butadiene.
-BI-S is preferable because it has better slipperiness, less stickiness, and is more excellent in preventing torque rise at opening.

The good slipperiness means that the amount of the lubricant added for preventing the rise of torque at the time of opening is small, the amount of the lubricant is small, the bleeding of the lubricant is very effective, and the feeling of stickiness is less. Is effective for the wax float problem. In that case, the mixing weight ratio (isoprene / butadiene) is 100/0 to 1/99, preferably 90/1.
0 to 35/65. These hydrogenated styrene / conjugated diene block copolymers have a weight average molecular weight of 5
000-500,000, preferably 100,00
0 to 400,000, particularly preferably 120,000 to
300,000, styrene content of 5 to 50% by weight, preferably 8 to 45% by weight, particularly preferably 10 to 40% by weight. 1, in the microstructure of the conjugated diene block
2- The microstructure is less than 20%, preferably less than 15%. The total amount of the 1,2-microstructure and 3,4-microstructure is less than 40%, preferably less than 35%, more preferably less than 30%. Hydrogenation rate is 9
5% or more, preferably 97 to 100% of a block copolymer is used. Here, the “weight average molecular weight” is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions.

(Conditions) Equipment: 150C ALC / GPC (MILLIPOR)
Column: AD80M / S (manufactured by Showa Denko KK) Solvent: o-dichlorobenzene Temperature: 140 ° C Flow rate: 1 ml / min Injection volume: 200 ml Concentration: 2 mg / ml (antioxidant) 0.2% by weight of 2,6-di-tert-butyl-p-phenol was added. The concentration was measured at a wavelength of 3.42 μm using an infrared spectrophotometer MIRAN1A manufactured by FOXBORO.

If the weight average molecular weight of the hydrogenated styrene / conjugated diene block copolymer is too large, the moldability tends to be poor. If the weight average molecular weight is too small, the rubber elasticity, mechanical strength and sealability tend to be poor. is there. As a method for producing a hydrogenated product of these styrene / conjugated diene block copolymers, for example, Japanese Patent Publication No.
No. 798, a styrene / conjugated diene block copolymer is synthesized in an inert solvent using a lithium catalyst, and then, for example, the hydrogenated SIS is described in 8704, JP-B-43-663
No. 6, JP-A-59-133203, JP-A-60-79
According to the methods described in the respective publications of No. 005, there can be mentioned a method of hydrogenation in an inert solvent in the presence of a hydrogenation catalyst.

As the hydrogenated S-BI-S, for example, those synthesized by the method described in JP-A-3-188114 can be mentioned. The above-mentioned hydrogenated styrene / conjugated diene block copolymer having a 1,2-microstructure of less than 20% is compared with a homopolymer of isoprene or isoprene or a block (a) composed of a polymer of styrene or a derivative thereof. And a total of 1,2 bond content and 3,4 bond content in the microstructure of the conjugated diene block (b) is 40% or more. Having a weight average molecular weight of 50,000 to 500,000,
A styrene-based block copolymer having a styrene content of 5 to 50% by weight or a hydrogenated product having a hydrogenation rate of 70% or more, preferably 80% or more is added to the component (A) in an amount of 1 to 50%.
By adding 50 wt%, preferably 5 to 30 wt%, the molten resin chip splashes in the shell when a certain amount of the extruded molten resin is dropped inside the shell of the synthetic resin cap during in-shell molding. This has a remarkable effect on prevention, and also improves fluidity and lowers the resin pressure during molding. (B) Rubber Softener and / or Liquid Paraffin [Component (B)] In the elastomer composition for a cap liner of the present invention, the rubber softener and / or liquid paraffin of the component (B) is used.

As a rubber softener , mineral oil or synthetic resin is suitable. The mineral oil-based softener is a combination mixture of an aromatic ring, a naphthene ring, and a paraffin chain,
Those having 50% or more of the total number of carbon atoms in the paraffin chain are called paraffinic and have a naphthene ring carbon number of 30 to
45% are naphthenic and have 30 aromatic carbons
More than% are called aromatics and are classified.
Among these, mineral oil-based softeners suitably used as the component (B) are paraffinic and naphthenic, and have an aromatic hydrocarbon content of 30% or less. Aromatic ones are not preferred in terms of dispersibility for the component (A). The mineral oil-based softening agent is not particularly limited, and known mineral oil-based softening agents can be used. Among them, preferable properties of the mineral oil-based softening agent include a kinematic viscosity at 40 ° C. of 20 to 800 cst, preferably 50 to 600 cst, and a pour point of −. At 45 to 0 ° C., preferably at −30 to 0 ° C., with a flash point (COC) of 170 to 40
A temperature of 0 ° C, preferably 200 to 350 ° C is used. Polybutene, low molecular weight polybutadiene and the like can be used as the synthetic resin-based softener.

Liquid paraffin Liquid paraffin belongs to the lubricating oil fraction in terms of boiling point, and is purified by removing impurities such as unsaturated components and aromatic components and sulfur components contained in the lubricating oil fraction. It is a mixture of high purity liquid saturated hydrocarbons. (C) Crystalline polypropylene resin and / or polyethylene resin [Component (C)] In the elastomer composition for a cap liner of the present invention, the crystalline polypropylene resin and / or polyethylene resin of the component (C) is used.

Crystalline polypropylene resin The crystalline polypropylene resin includes propylene homopolymer, propylene and ethylene and / or C 4-12
Having a degree of crystallinity of at least 35% by X-ray diffraction, preferably from 40% to 80%.
Is used. The above-mentioned crystalline polypropylene resin has a melt flow rate (JIS-K6758, 230
℃ 2.16kg load) 0.1-100g / 10min,
Preferably 1 to 70 g / 10 min, particularly preferably 5 to 5 g
The thing of 0 g / 10 minutes is used.

Polyethylene resin As the polyethylene resin, a melt flow rate (JIS-K67) obtained by a known method such as a low pressure polymerization method is used.
60, 190 ° C, 2.16kg load) 0.1-50g
For example, a polyethylene resin having a density of 0.940 g / cm ³ or more, preferably 0.945 g / cm ³ or more is used.

(2) Additional Component (Optional Component) The elastomer composition for a cap liner used in the present invention may contain an additional component as long as the effects of the present invention are not significantly impaired. Examples of the additional component include phenol-based and / or phosphorus-based antioxidants, hindered amine-based light stabilizers, neutralizing agents such as metal soaps and / or hydrotalcites, higher fatty acids, Lubricants such as waxes, silicone oil, silicone gum, higher fatty acid amides, organic and inorganic pigments such as titanium oxide and phthalocyanine blue, metal deactivators,
Antistatic agents, fillers, peroxides, nucleating agents, low-density polyethylene, linear low-density polyethylene, ethylene
Examples thereof include a vinyl acetate copolymer. Among these additional components, to improve the openability during actual use,
A lubricant such as a higher fatty acid, a wax, a silicone oil, a silicone gum, a higher fatty acid amide or the like is usually used in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the composition composed of the components (A) to (C). It is particularly preferable to add it in the range of 0.3 to 5 parts by weight.

(3) Blending Ratio The blending ratio of each of the above components in the elastomer composition for a cap liner used in the present invention is as follows: the (A) component which is a hydrogenated product of a styrene / conjugated diene block copolymer and the rubber softening agent. For the component (B), which is an agent and / or a liquid paraffin,
Component (A) is 45 to 70% by weight, preferably 50 to 65% by weight.
%, Particularly preferably 55 to 60% by weight, and the component (B) is 55 to 30% by weight, preferably 50 to 35% by weight, particularly preferably 45 to 40% by weight. If the component (A) is less than the above range, the wax float deteriorates. On the other hand, when the component (A) exceeds the above range, the moldability deteriorates,
In addition, the flexibility of the composition is reduced, and the hermetic sealing properties as a liner are deteriorated. The amount of the component (C), which is a crystalline polypropylene resin and / or a polyethylene resin, is 5 to 100 parts by weight, preferably 10 to 70 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). And particularly preferably 15 to 50 parts by weight. If the compounding ratio of the component (C) is less than the above range, the molding processability of the obtained composition is deteriorated, and the composition becomes too soft, so that the material strength is reduced and the abrasion is also deteriorated. On the other hand, when the ratio exceeds the above range, the flexibility of the composition is reduced, and the hermetic sealability as a liner is deteriorated.

(4) Preparation of Composition The elastomer composition for a cap liner of the present invention comprises the above components (A), (B) and (C), and if necessary additional components, in a known manner, for example, After mechanically mixing with a Henschel mixer, a V blender, a tumbler blender or the like, it can be produced by known mechanical melting and kneading. For the mechanical melt kneading, a general melt kneader such as a Banbury mixer, various kneaders, a single screw or twin screw extruder can be used.

[C] Hardness of Liner Material The hardness of the liner material according to the present invention is JIS-A hardness (J
ISK6301) is 50 to 95, preferably 60 to 85.
It is. If the hardness (JIS-A) is less than 50, the material strength of the liner is weak, so that there is a problem that the liner is worn when the cap is opened and closed and in contact friction with the container opening. And poor molding stability. Conversely, if the hardness (JIS-A) exceeds 90, it is too hard to sufficiently adhere to the mouth of the container, the compression set is deteriorated, and the hermetic sealing of the contents of the container is impaired.

[D] Molding of cap liner The elastomer composition for a cap liner of the present invention is hermetically molded in a cap shell using a known liner molding method. As a liner molding method, for example, the elastomer composition for a cap liner is used in a range of 0.5 to 1.0 m.
After molding into a sheet with a thickness of m, punching into a diameter that matches the shape of the cap, inserting it into the cap and bonding it, or dropping a certain amount of extruded molten resin inside the cap and cooling An in-shell molding method in which a liner shape is formed by embossing downward can be given. Note that the in-shell molding method is an excellent molding method in terms of mass productivity. When the cap liner obtained by the above molding is layered on the inner surface of the cap, and the cap is put on the mouth of the bottle and tightened, a screw-like projection formed on the outer periphery of the mouth of the bottle is formed. The screw portion formed on the inside of the cap meshes, and the mouth of the bottle comes into contact with the flat surface (the horizontal portion and the vertical portion with respect to the mouth of the bottle) of the liner on the inner surface of the cap. This prevents bleeding of additives such as wax floats and lubricants caused by liquid paraffin, increases hermetic sealing by screw-shaped engagement, and increases liquidity by elasticity caused by the shape, hardness and material of the liner. It prevents leakage and facilitates opening.

[E] Caps The caps for which the elastomer composition for a cap liner of the present invention is used include PET bottle containers such as various tea drinks, fruit drinks, vegetable drinks, carbonated drinks, soft drinks, mineral water, beer bottles, and whiskeys. Examples of the cap include containers for liquor bottles such as bottles for wine, bottles for sake, bottles for sake, etc., wide-mouthed bottles for foods such as jam and enokitake, and small bottles for drinks. Among these, a container cap used for a PET bottle container is preferable.

[0028]

EXAMPLES Examples and comparative examples are shown below, but the present invention is not limited to the following examples as long as the gist is not exceeded. Examples 1 to 9 and Comparative Examples 1 to 13 (1) Raw materials used (A) Component: hydrogenated styrene / conjugated diene block copolymer

[0029]

[Table 1]

Component (B): Rubber softener B-1 Idemitsu Kosan Co., Ltd. paraffin rubber softener PW90 (trade name) Kinematic viscosity (40 ° C.): 95.5 cst, Pour point: -15.0 ° C Flash point (COC): 272 ° C (C) component: crystalline polypropylene resin C-1 Novatec PPMA03 manufactured by Nippon Polychem Co., Ltd. Melt flow rate (230 ° C, 2.16 kg) 25 g / 10 minutes High density polyethylene resin C- 2 Novatec HDHJ49 manufactured by Nippon Polychem Co., Ltd.
0 Melt flow rate (190 ° C, 2.16 kg) 20 g / 10 min

(2) Production of Composition The above-mentioned raw materials were blended in the proportions of the components shown in Table 2 (Examples) and Table 3 (Comparative Examples). 0.5 part by weight of erucic acid amide) and 0.1 part by weight of a phthalocyanine blue face were added and mixed with a Henschel mixer, and then mixed with a twin screw extruder having an L / D of 33 and a cylinder diameter of 45 mm. The mixture was melt-kneaded at a set temperature to obtain pellets of the liner composition. (3) Molding of Liner The obtained composition for a cap liner was molded at a temperature of 210 ° C. by an in-shell molding method in a 28 mmφ polypropylene cap shell as shown in FIGS. In addition, cutting and overlaying of the mold were sequentially performed to obtain liner-shaped products of Examples and Comparative Examples. (4) Evaluation Next, the following physical properties were evaluated. The results are shown in Table 2 (Example) and Table 3 (Comparative Example). In addition, for the measurement samples of the following evaluations, pellets of the above composition for a cap liner were mixed with an in-line screw type injection molding machine (a small injection molding machine manufactured by Toshiba Machine Co., Ltd .:
120 mm molded at an injection pressure of 500 kg / cm ² , an injection temperature of 220 ° C., and a mold temperature of 40 ° C. according to IS90B).
A × 80 mm × 2 mm (thick) sheet was used.

For the measurement samples of the following evaluations, a liner-formed polypropylene cap obtained by molding into a liner by the in-shell mold method described above was used. (The container is a 1.5 liter PET bottle.) JIS-A hardness: based on JIS-K6301. Compression set: Based on JIS-K6301 (70 ° C, 22 hours). Liner moldability: Each composition was molded into a liner at 210 ° C. in a cap shell by an in-shell mold method, and the obtained 100 cap liners were visually inspected and evaluated according to the following criteria. ：: There is no molding failure of the liner. ×: Molding defects such as bubbles, chips, burrs and the like of the liner were 1% or more. Hermetic sealability: 1.5 liter PE using a cap with a liner obtained by in-shell molding
Fill the T bottle with mineral water at 95 ° C, wind it with a tightening torque of 11.0 kg · cm using a Magna Torque head (trade name) of a capping machine manufactured by Alcoa, and seal the container with mineral water for another 30 minutes. After falling over for 2 seconds, sterilization treatment was performed for 3 minutes with a hot water shower at 90 ° C. (Test number: 10) 漏 れ: no leak at all ×: leak at least even at 1 piece Opening property: the sample container after tightening the cap at 60 ° C.
After storing in a thermostat and a 5 ° C. refrigerator for one week, the opening torque value was measured, and the measured torque value was evaluated according to the following criteria. (10 tests) ：: All suitable values of torque (10 to 20 kg · cm) △: Intermediate torque (5 to 10 kg · cm or 20 to 25)
(kg / cm or more). ×: inappropriate torque value (less than 5 kg · cm or 25 kg · cm)
cm or more). Abrasion: The cap sample with the liner was manually wound around the mouth of the PET bottle container, and the operation of tightening and opening was repeated 10 times, and the degree of abrasion of the liner was observed and evaluated according to the following criteria.
(Number of tests: 10) ：: No wear (fuzzing, shaving) was observed. X: Abrasion (fuzz, shaving) was observed even a little. Wax float: The sample container after tightening the cap was turned over, stored in a constant temperature bath at 40 ° C. for 48 hours, and then returned to room temperature, and the presence or absence of wax float on the liquid surface was visually checked. ○: No ×: Yes

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

Industrial Applicability The liner of the synthetic resin cap of the present invention has good in-shell moldability, and is subjected to hot filling and heat sterilization of an inner solution such as a soft drink, and sterilization of containers, caps and liners. No liquid leakage even after aseptic filling after pre-processing and filling at room temperature,
In addition, it has good hermetic sealing properties without lowering the internal pressure even in internal solutions such as carbonated beverages, easy to open in actual use, and liner wear due to contact friction with the container opening when opening and closing. It is preferably used as a liner material used for sealing a synthetic resin cap having improved hygiene and improved hygiene in which elution from the liner material is prevented.

[Brief description of the drawings]

FIG. 1 is a partially cut drawing of a container cap with a liner.

FIG. 2 is a partially cut drawing of a container cap with a liner.

FIG. 3 is a partially cut drawing of a container mouth.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liner part which contacts the front-end | top surface of a container mouth part 2 Liner part which contacts the outer peripheral part of a container-mouth part front-end 3 Liner part which contacts the inner peripheral part of a container-mouth front-end 4 Top-top surface of a container mouth part 5 Container Outer peripheral part at the tip of the mouth 6 Inner peripheral part at the tip of the container mouth

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23/10 C08L 23/10 53/02 53/02 83/04 83/04 91/00 91/00 / / C08J 5/00 CER C08J 5/00 CER F term (reference) 3E084 AA04 AA12 AA24 AB01 BA02 CC03 DA01 DB12 DC03 FA09 GA01 GB01 HA02 HB04 HC06 HD01 4F071 AA15 AA15X AA20 AA20X AA21X AA71 BB04 AE04 A05 AE04 A05 AE04 BC BP01W CP03Z EF056 EP016 FD040 FD070 FD090 FD176 GG01

Claims (2)

[Claims] 1. A liner joined to the inside of the top surface of a synthetic resin screw-in cap, wherein an average thickness of a top surface contact liner portion which comes into contact with a top surface of a front end of a container mouth is 0.3 to 1 .5 mm, outer periphery near the end of the container mouth and / or
Alternatively, the average height of the liner rising portion in contact with the inner peripheral portion is 0.3 to 2 mm from the thickness of the top surface contact liner portion.
High, and the average thickness of the liner rising part is
3 to 1.5 mm, and the hardness of the liner (JIS-
A) wherein A) is in the range of 50 to 95 and the composition of the liner comprises the following components (A), (B) and (C). Component (A): a hydrogenated product of a styrene / conjugated diene block copolymer, wherein the conjugated diene is isoprene alone or a mixture of isoprene and butadiene (mixing weight ratio of isoprene and butadiene 100/0 to 1/99). The hydrogenated product of the copolymer was added to the total amount of (A) and (B),
45 to 70% by weight (B) Component: 30 to 55% by weight of rubber softener and / or liquid paraffin based on the total amount of (A) and (B) (C) component; melt flow rate (230 ° C., 2.16
(kg load) of 0.1 to 100 g / 10 min of crystalline polypropylene resin and / or melt flow rate (190
C., 2.16 kg load) with a polyethylene resin having a density of 0.1 to 50 g / 10 min and a density of 0.940 g / cm < ³ > or more based on 100 parts by weight of the total amount of (A) and (B).
0 parts by weight 2. A composition comprising 0.05 to 10 parts by weight of a lubricant based on 100 parts by weight of an elastomer composition comprising the components (A), (B) and (C). Item 2. The cap liner according to Item 1.