JP5774944B2 - LINER MATERIAL RESIN COMPOSITION FOR TWIST CAP AND METHOD FOR PRODUCING TWIST CAP FOR FOOD BOTTLING - Google Patents

Description

  The present invention relates to a liner cap resin material composition for twist caps and a method for producing a twist cap for food bottling.

  Conventionally, vinyl chloride plastisol has been used as a liner material for medium- to large-diameter twist caps such as metal screw caps for food bottling and metal lug caps.

  The vinyl chloride plastisol liner material is widely used because of its excellent sealing function, excellent handling workability, and stable physical properties, properties and quality.

  However, in recent years, it has been required to consider the environment and food hygiene, but the vinyl chloride plastisol liner material has problems with these. For example, it has been pointed out that vinyl chloride resin has a problem of generating chlorine gas at the time of incineration and damaging the incinerator and a problem of photochemical smog. Plasticizer, an essential component of vinyl chloride plastisol, is a concern about adverse effects on the human body due to the transition to food contents, environmental pollution of soil and rivers, and the corrosion resistance of the coating film applied to the inner surface of the torsion cap body. Deterioration problems have been pointed out.

  As a technique for dealing with these problems, a liner material mainly composed of an elastomer has been studied. For example, a liner material mainly composed of a two-pack type or a one-pack type urethane elastomer is partially used as a liner material for a twist cap for food bottling.

  However, urethane elastomers have not been widely used due to problems in handling workability and food hygiene.

  As a liner material mainly composed of an elastomer, a small-diameter cap for beverages, for example, has been proposed in which a styrene elastomer, a polypropylene resin, and liquid paraffin are blended (see Patent Documents 1 to 7).

JP 2007-63392 A JP 2005-111758 A JP 2004-263093 A JP 2003-286408 A JP-A-11-106565 JP-A-11-130910 Japanese Patent No. 423972

  However, the liner material using this styrenic elastomer has been studied for small-sized caps for beverages such as metal PP (pill fur proof) caps and synthetic resin caps. It has not been studied for medium to large diameter twist caps (pre-formed caps) such as caps and metal lug caps. One of the reasons is that it has been considered that it is difficult to ensure sealing performance and openability with a twisted cap.

  In addition, the liner material for twist caps for food bottles has other required properties, such as corrosion resistance of the coating film applied to the inner surface of the twist cap body, heat resistance during heat sterilization, food contamination resistance, flavor However, a composition that satisfies all of these requirements in a liner material using a styrene elastomer has not been studied.

  The present invention has been made in view of the circumstances as described above, does not contain chemical substances such as chlorine and plasticizers that may cause environmental pollution and adverse effects on the human body, and sealability, openability, corrosion resistance , Torsion cap liner material capable of satisfying practicality of twist caps for food bottling, heat resistance, food contamination resistance and flavor, and manufacture of twist caps for food bottling The challenge is to provide a method.

  In order to solve the above-described problems, a twisted cap liner material resin composition of the present invention is a twisted cap liner material resin composition used in a twisted cap for food bottling, wherein the styrene elastomer (A), polypropylene -Based resin (B), liquid paraffin (C), and lubricant (D), styrene-based elastomer (A) has a styrene content of 30 to 33% by mass, and ethylene-ethylene-propylene as an elastomer block (EEP) or ethylene-butylene (EB), the melt flow rate (MFR) at 230 ° C. and 2.16 kg / 10 min is 0, and the total amount of (A), (B), (C) Styrene elastomer (A) 15-30% by mass, polypropylene resin (B) 5-25% by mass, liquid paraffin C) 45 to 65 wt%, it is characterized in that it contains 1.5 to 10 wt% lubricant (D).

  In this twist cap liner material resin composition, as the lubricant (D), 0.5 to 2.0% by mass of a higher fatty acid amide with respect to the total amount of (A), (B) and (C), silicone It is preferable to contain 1.0-8.0 mass% of oil.

  The method for producing a twist cap for a food bottle according to the present invention includes a step of applying and curing the liner cap resin material composition for a twist cap on the sealing surface of the twist cap body for food bottle filling with the bottle mouth. It is characterized by.

  In this twist cap manufacturing method, it is preferable that the JIS A hardness of the liner material formed on the sealing surface of the twist cap body with the bottle mouth by the curing is 20-60.

  In this twist cap manufacturing method, it is preferable to use a twist cap body in which an epoxy phenol-based paint containing acid-modified polypropylene resin powder is coated on a sealing surface with a bottle mouth.

  According to the present invention, it does not contain chemical substances such as chlorine and plasticizers that have environmental pollution or adverse effects on the human body, and it has a sealing property, an opening property, a corrosion resistance, a heat resistance, a food contamination resistance, and a flavor property. It can be satisfied to a practical degree with a twist cap for bottled goods.

It is sectional drawing which shows the form of the liner material in the twist cap for a foodstuff bottling, and a drink bottle cap.

  The present invention is described in detail below.

  The present invention relates to a twister cap liner material resin composition used in a twist cap for food bottling, in a styrene elastomer (A), a polypropylene resin (B), liquid paraffin (C), and a lubricant (D ) Was formulated as a specific composition, and was completed based on the fact that a liner material suitable for a twist cap for food bottling could be obtained.

  Conventionally, liner materials blended with styrene elastomer, polypropylene resin, and liquid paraffin are caps made of synthetic resin such as PET bottles, or small caps for beverage containers such as metal PP caps such as bottle cans and small bottles. It was used for (a small diameter cap of about 30φ).

  On the other hand, the present invention is directed to a medium to large-diameter twist cap for bottling food products of, for example, about 60 ± 20φ.

  Such a twist cap is completely different from the small cap of a beverage container in the required performance of the liner material, and also differs in terms of design concept and physical properties. The present invention is characterized in that the components (A) to (D) are examined from a viewpoint specific to the twist cap for food bottling and used in a specific composition in such a twist cap for food bottling. .

  That is, the small cap of the beverage container of the prior art is usually molded, and the sealing portion of the sealing surface 101a of the beverage bottle cap main body 101 by the liner material 102 is the top of the bottle can mouth 103 as shown in FIG. With a shape that covers the periphery of the part, the seal area is wide.

  On the other hand, as shown in FIG. 1A, the liner material of the present invention has the liner material 2 molded flat on the sealing surface 1a of the twisted cap body 1, and the sealing surface is only at the top of the bottle mouth 3. The seal area is small.

  The conventional technique as shown in FIG. 1 (b) is fitted (rolled) while applying a large load of about 100 kgf from above, despite a small diameter, while ensuring perfect sealing. The twist cap for food bottling used in the present invention is wound with a relatively small torque of 2 to 5 Nm regardless of the medium diameter to the large diameter. For this reason, there is a limit to the liner material biting into the bottle opening.

  Therefore, the liner material of the medium to large-diameter twist cap for food bottling needs to be a soft gasket in which the top of the bottle mouth is easy to bite in order to ensure sealing.

  The food bottling product to which the present invention is applied is usually subjected to high-temperature sterilization treatment, and therefore the liner material is required to have heat resistance. Therefore, the elastomer and olefin resin must have heat resistance. Moreover, since the liner material of this invention is used for the twist cap of medium diameter-large diameter, it is necessary to make it a liner material which is easy to open. Therefore, the selection of the lubricant is important.

  The compounding composition designed in consideration of these is the present invention. According to the study by the present inventors, the use of a styrene-based elastomer having a large molecular weight to ensure heat resistance is required with a small compounding ratio. Heat resistance. In addition, a polypropylene resin was used as the olefin resin from the viewpoint of ensuring heat resistance, and the heat resistance could be ensured even though the blending ratio was reduced to make it a soft liner material. And in this invention, white oil has many compounding quantities compared with the existing liner material. This has the purpose of softening the liner material, but despite the fact that it was blended in large quantities, it was possible to achieve a blend that did not impair the performance required for the liner material, particularly heat resistance. Furthermore, by adding higher fatty acid amide or the like as a lubricant, it was possible to obtain a torsion cap that could be opened with an appropriate torque and the lubricant did not fall into the contents.

  The styrene-based elastomer (A) blended in the twister cap liner material resin composition of the present invention is composed of a styrene polymer block and an elastomer block, and the styrene content is 30 to 33% by mass. When the styrene content is within this range, the heat resistance of the liner material and the sealing property due to the elasticity of the elastomer can be ensured.

  Examples of the styrene monomer used in the styrene polymer block include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N, N-diethyl-p-amino. Examples thereof include ethylstyrene and N, N-vinylpyridine. Of these, styrene and α-methylstyrene are preferable.

  The elastomer block contains ethylene-butylene (EB) or ethylene-ethylene-propylene (EEP: hydrogenated isoprene structure).

  As the block structure, A: styrene polymer block, B: elastomer block, ABA type can be used, and can be used alone or as a blend of two or more.

  For example, the SEEPS type and SEBS type having the following structure can be used.

(In the formula, PS is a polystyrene unit, the square brackets are random copolymers, and m and n are integers of 1 or more.)

(In the formula, PS is a polystyrene unit, the square brackets are random copolymers, and m and n are integers of 1 or more.)
These are hydrogenated modified products obtained by obtaining a copolymer of styrene polymer block-elastomer block-styrene polymer block and then hydrogenating the copolymer.

  The styrene elastomer (A) is a powder having a high molecular weight and excellent heat resistance, having a melt flow rate (MFR) of 0 at 230 ° C. and 2.16 kg / 10 min (JIS K7210). By using the powder having excellent heat resistance, the food bottled product can be sterilized at high temperature.

  That is, by using this non-flowable block copolymer, the liner material is flexible at room temperature and particularly excellent in rubber elasticity when heated. At 130 ° C, the compressive stress does not decrease so much, and as a result, leakage (liquid leakage) due to thermal deformation or heat shrinkage is effectively suppressed under heat sterilization conditions at 130 ° C for 30 minutes, and also during storage and handling Leakage due to the falling of the water is also effectively suppressed.

  This styrenic elastomer (A) has flexibility, low modulus, excellent elasticity, heat resistance, weather resistance, hygiene, etc., and good compatibility with polypropylene resin (B) and liquid paraffin (C). It is.

  The styrene elastomer (A) preferably has a specific gravity of 0.88 to 0.94 and a solution viscosity (5 mass% toluene solution) of preferably 20 to 700 mPa · s. If the solution viscosity is too low, fluidity may occur in the elastomer at the time of molding. If the solution viscosity is too high, the elastomer becomes hard, and the fluidity and molding processability of the resin composition tend to deteriorate.

  Content of the styrene-type elastomer (A) in the liner material resin composition for twist caps of this invention is 15-30 mass% with respect to the total amount of (A), (B), (C). When there is too little content of a styrene-type elastomer (A), the elasticity of a liner material will be lost and sealing performance will fall. When there is too much content of a styrene-type elastomer (A), a liner material will become weak and compression fracture will occur easily.

  The polypropylene resin (B) blended in the torsion cap liner material resin composition of the present invention can impart thermoformability without reducing the compressive stress in the heat sterilization treatment (for example, 130 ° C.).

  In general, by adding an olefin resin, heat moldability can be imparted, but food bottling products are usually subjected to hot pack (heat filling) or high temperature heat sterilization treatment after filling. Therefore, since heat resistance is required for the liner material, it is essential to use a polypropylene resin instead of a polyethylene resin as the olefin resin.

As the polypropylene resin, for example, a homopolymer of propylene, a copolymer of propylene (main component) and ethylene and / or an α-olefin having 4 to 12 carbon atoms can be used. For example, a polypropylene resin having the following physical properties can be preferably used.
MFR (230 degreeC, 2.16kg / 10min JIS K7210): 1-60
Specific gravity: 0.89-0.92
Hardness (Rockwell R type): 80-120
Thermal deformation temperature (0.45 MPa, ASTM D648): 70 to 110 ° C.
When the MFR is in the above range, the moldability of the twisted cap liner material resin composition is good, and the heat sealing property and impact resistance as the twist cap are also excellent.

  The content of the polypropylene resin in the liner cap resin material composition of the present invention is 5 to 25% by mass with respect to the total amount of (A), (B), and (C). By setting the content of the polypropylene resin within this range, the hardness, tensile strength, heat resistance, etc. of the compound can be obtained in a balanced manner. If the content of polypropylene resin is too small, film formation may not be possible as a liner material. Even if film formation is possible, the film is brittle and has poor tensile strength, and may break when wound on bottles or when sterilized. . When there is too much content of polypropylene resin, hardness will become high too much, the bite into a bottle mouth will worsen, and sealability will be inferior.

  The liquid paraffin (C) blended in the twister cap liner material resin composition of the present invention is compatible with the styrene-based elastomer (A) and the polyethylene-based resin (B) to enable molding.

  That is, liquid paraffin (C) imparts flexibility and heat moldability, and is tasteless and odorless compared to other oils, so that it has little influence on the flavor of food contents and is effective.

  Liquid paraffin (C) is a hydrocarbon oil obtained by highly purifying a relatively light lubricating oil fraction, such as a spindle oil fraction, by washing with sulfuric acid. It is colorless and odorless and has low volatility and is mainly composed of alkyl naphthenes. It is also called oil (white oil).

  In particular, the properties of refined liquid paraffin of the medicinal class are defined in 6 stations (d 0.860-0.905: published by Kyoritsu Shuppan Co., Ltd., February 15, 1987, see page 749 of Chemistry Dictionary 9). Such refined liquid paraffin is particularly suitable because the contents are foodstuffs.

The kinematic viscosity of the liquid paraffin (C) is preferably 20 to 70 mm ² / s (40 ° C.) in consideration of heat resistance, suppression of elution to bleed and contents, molding processability and the like.

  Content of a liquid paraffin (C) is 45-65 mass% with respect to the total amount of (A), (B), (C). By setting the content within this range, the physical properties centered on the fluidity and hardness of the torsion cap liner material resin composition can be made within an appropriate range.

  A lubricant (D) is blended in the liner cap resin material composition of the present invention. The opening torque of torsion caps is generally set to cap diameter (cm) x 2/4 ± 1/4 N · m, but by adding lubricant (D), the opening torque should be within this range. Can do.

  As the lubricant (D), a higher fatty acid amide or silicone oil is mainly blended. By blending them, the lubricant (D) bleeds on the surface of the liner material, so that the twist cap can be opened and closed smoothly (appropriate torque). In a preferred configuration, the lubricant (D) is 0.5 to 2.0% by mass of a higher fatty acid amide and 1.0 to 8.0 silicone oil based on the total amount of (A), (B) and (C). Contains mass%.

  Higher fatty acid amides are excellent in lubricity and have a great effect of reducing the opening torque, but if the amount of bleed on the liner material surface is large, the higher fatty acid amides may fall into the contents or even adversely affect the flavor. is there. Considering such points, the content of the higher fatty acid amide is preferably 0.5 to 2.0 parts by mass with respect to the total amount of (A), (B), and (C).

  Examples of higher fatty acid amides include oleic acid amide, erucic acid amide, stearic acid amide, palmitic acid amide, lauric acid amide, methylene bis stearyl amide, ethylene bis lauryl amide, stearyl oleyl amide, linoleic acid amide, linolenic acid amide, etc. Can be mentioned. Of these, oleic acid amide and erucic acid amide are preferable.

  Silicone oil can provide smoothness to the surface of the liner material and improve the tightness of the torsion cap. The silicone oil content depends on the blending ratio of each component (A), (B), and (C), but it gives smoothness to the liner material surface and suppresses bleeding even when there is a lot of liquid paraffin. However, considering suppression of a decrease in the flavor of the contents, the content is preferably 1.0 to 8.0% by mass with respect to the total amount of (A), (B), and (C).

The silicone oil is preferably one having a kinematic viscosity of 100 to 10,000 mm ² / s (20 ° C.) in consideration of food hygiene and the mixing and dispersibility of the twisted cap liner material. A dimethyl silicone oil, a methylphenyl silicone oil or the like having a kinematic viscosity in such a range is preferable.

  Other additives can be blended in the liner cap resin material composition of the present invention as long as the effect is not impaired. Examples of such other additives include pigments, barrier materials, and antioxidants.

  The pigment is added for coloring the liner material. For example, titanium oxide can be used. Content of titanium oxide can be 0.5-1.0 mass% with respect to the total amount of (A), (B), (C), for example.

  The barrier material is added to improve the gas permeability of the liner material. For example, an isoprene-based elastomer can be used. The content of the isoprene-based elastomer is, for example, 20 to 30% by mass with respect to the total amount of (A), (B), and (C).

  As the antioxidant, for example, pentaerythritol “3- (3,3-ditert-butyl-4-hydroxyphenyl) propionate” or the like can be used.

  The twisted cap liner material resin composition of the present invention is prepared by mixing each component such as (A), (B), (C), (D) with a known method, for example, a Henschel mixer, a V blender, etc. It can be prepared by melt-kneading with an extruder, twin-screw extruder, Banbury mixer, etc., granulating, pulverizing and the like.

  The twist cap for food bottling according to the present invention is obtained by applying and curing the twisted cap liner material resin composition prepared as described above to the sealing surface of the twist cap main body for food bottling with the bottle mouth. Can be manufactured.

  For example, a method of extruding a certain amount of a liner cap resin material composition for a twist cap onto the inner surface of the cap body with a hot melt extruder and embossing under cooling can be used.

  As the torsion cap body, one in which an epoxy phenol-based paint containing polypropylene resin powder is coated on the sealing surface with the bottle mouth is preferably used. The epoxy phenolic paint usually used for coating on the inner surface of the cap has corrosion resistance, but cannot sufficiently adhere to the liner material by the liner cap resin material composition of the present invention. However, by blending the polypropylene resin powder with the epoxy phenol paint, the polypropylene resins are fused and integrated at the time of molding to obtain strong adhesion, and it is possible to ensure strong adhesion with the liner material. Moreover, corrosion resistance does not deteriorate.

  An acid-modified polypropylene resin can be used as the polypropylene resin powder. The content of the polypropylene resin powder is preferably 5 to 20% by mass with respect to the total amount of the epoxy phenol paint (including the polypropylene resin powder).

  In addition, in the case of liner materials made of vinyl chloride plastisol, which are widely used, vinyl chloride paints are used because they only adhere to vinyl chloride paints. However, the corrosion resistance of vinyl chloride paints is inherently weak, and the liner material is hardened and baked. Occasionally, since the coating film is melted and bonded with a plasticizer in vinyl chloride plastisol, the corrosion resistance of the periphery melted by the plasticizer is further reduced, but the epoxy phenolic paint containing the above polypropylene resin powder and the present According to the combination with the liner material by the liner cap resin material composition of the invention, the corrosion resistance is not deteriorated.

  The JIS A hardness of the liner material formed on the sealing surface of the twist cap body with the bottle mouth by curing of the twist cap liner material resin composition is preferably 20-60. If the hardness is too small, the impact resilience will decrease, and if the hardness is too large, it will be too hard to bite into the bottle mouth and the sealing and impact resistance will decrease.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
<Example 1>
The following components were blended in the blending amounts (parts by mass) shown in Table 1 to prepare a twisted cap liner material resin composition.
(Styrene elastomer)
Styrene elastomer (SEEPS type) containing ethylene-ethylene-propylene (EEP) as an elastomer block, styrene content 30% by weight, specific gravity 0.91, MFR0, viscosity of 5% by weight toluene solution 670 mPa · s (30 ° C.)
(Polypropylene resin)
Density 0.9, 230 ° C, MFR24
(Liquid paraffin)
Matsumura Oil Research Co., Ltd., kinematic viscosity 68mm ² / s (40 ° C)
(lubricant)
Oleic acid amide, Lion Axo erucic acid amide, Lion Axo silicone oil, Shin-Etsu Chemical Co., Ltd., Kinematic viscosity 350mm ² / s (25 ° C)
(Pigment)
Titanium oxide, Sakai Chemical Industry Co., Ltd. The MFR of styrene elastomer and polypropylene resin is a value measured under the conditions of 230 ° C. and 2.16 kg / 10 min using a melt index tester manufactured by Yasuda Seiki Seisakusho Co., Ltd. is there.

  30 parts by mass of styrene elastomer, 15 parts by mass of polypropylene resin, 55 parts by mass of liquid paraffin, 0.5 parts by mass of oleic acid amide, 0.5 parts by mass of erucic acid amide, 5 parts by mass of silicone oil, 0.6 mass of titanium oxide The part was kneaded and melted at 180 ° C. for 80 minutes with a kneader to obtain a resin material composition (compound) for a twist cap.

The following evaluation was performed about this liner material resin composition for twist caps.
[hardness]
The liner cap resin material composition for twist caps was cured with a hot press heated to 190 ° C. to prepare a 2 mm thick sheet. The hardness of this sheet was measured at 25 ° C. using a JIS K6301 TYPE A hardness meter.
[Tensile strength / elongation]
The liner cap resin material composition for twist caps was cured with a hot press heated to 190 ° C. to prepare a 2 mm thick sheet. The tensile strength of this sheet was measured according to JIS K6251 using a STROGRAPH VE5D type manufactured by Toyo Seiki Seisakusho.

Specifically, measurement was performed at a test piece shape: dumbbell-shaped No. 3, tensile speed: 500 mm, measurement temperature: 25 ° C., and the tensile strength at 500% elongation was 2 MPa or more, and less than this was evaluated as x. In addition, the thing which elongation did not reach to 500% and broke in the middle was set as x.
[Real bottle test]
In order to evaluate the performance of the resin composition for the twist cap liner material as a liner material, a 0.8 mm thick sealing gasket was molded on a 62φ screw cap by hot pressing and subjected to a real bottle test.

  In addition, the epoxy phenol-type paint which mix | blended acid-modified polypropylene-type resin powder was painted on the sealing surface side of the cap main body which laminates sealing gasket.

Fill a commercial jam bottle with 80 ° C warm water, wind the cap with a torque of 3.5 N · m, perform 90 ° C x 60 min immersion sterilization and 118 ° C x 80 min pressure sterilization, then cool Thereafter, it was stored at 5 ° C., RT, and 38 ° C. for 40 days, and then the sealing property (vacuum degree), the opening property (opening torque), and the state of the liner material were evaluated according to the following criteria. The degree of vacuum was measured at 25 ° C. using a VACUUM CANTESTER manufactured by Yokoyama Keiki Co., Ltd., and the opening torque was measured using a torque meter manufactured by Shinpo Kogyo Co., Ltd. (MODELTNK-100B). .
(Degree of vacuum)
○: Degree of vacuum is 20 kPa or more ×: Degree of vacuum is less than 20 kPa (opening torque)
○: Opening torque is 1.6 to 4.6 N · m
×: Other than above (liner material state)
A: The trace of biting into the liner material at the bottleneck rim is normal.
X: The bite is too shallow or too deep, or sagging due to breakage or softening of the liner material occurs.
<Example 2>
In Example 1, the styrene elastomer was changed to 15 parts by mass, the polypropylene resin was changed to 25 parts by mass, and the liquid paraffin was changed to 60 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Example 3>
In Example 1, the polypropylene resin was changed to 5 parts by mass and the liquid paraffin was changed to 65 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Example 4>
In Example 1, the styrene elastomer was changed to 20 parts by mass, the polypropylene resin was changed to 25 parts by mass, and the liquid paraffin was changed to 55 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Example 5>
In Example 1, the polypropylene resin was changed to 25 parts by mass and the liquid paraffin was changed to 45 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Example 6>
In Example 1, the styrene elastomer was changed to 20 parts by mass and the liquid paraffin was changed to 65 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Example 7>
In Example 5, a styrene elastomer containing ethylene-butylene (EB) with a styrene elastomer as an elastomer block (SEBS type: styrene content 33 mass%, specific gravity 0.92, MFR 0, viscosity of 5 mass% toluene solution 42 mPa -It changed to s (30 degreeC). Other than that, it processed similarly to Example 5, and performed the measurement of A hardness and tensile strength, and the evaluation by a real bottle test.
<Comparative Example 1>
In Example 1, the styrene elastomer was changed to 10 parts by mass, the polypropylene resin was changed to 25 parts by mass, and the liquid paraffin was changed to 65 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Comparative Example 2>
In Example 1, the styrene elastomer was changed to 50 parts by mass, the polypropylene resin was changed to 5 parts by mass, and the liquid paraffin was changed to 45 parts by mass. Other than that, it processed like Example 1, and tried the measurement of A hardness and tensile strength, and the evaluation by a real bottle test. However, this blended composition could not be melt-kneaded in the kneader kneading step, resulting in a puffy state and could not proceed to the subsequent step. This is thought to be due to the small proportion of polypropylene resin.
<Comparative Example 3>
In Example 1, the styrene elastomer was changed to 20 parts by mass, the polypropylene resin was changed to 30 parts by mass, and the liquid paraffin was changed to 50 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Comparative Example 4>
In Example 1, the styrene elastomer was changed to 40 parts by mass, the polypropylene resin was changed to 20 parts by mass, and the liquid paraffin was changed to 40 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Comparative Example 5>
In Example 1, the styrene elastomer was changed to 25 parts by mass, the polypropylene resin was changed to 5 parts by mass, and the liquid paraffin was changed to 70 parts by mass. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.
<Comparative Example 6>
In Example 5, a styrene elastomer containing ethylene-propylene (EP) with a styrene elastomer as an elastomer block (styrene content 20 mass%, specific gravity 0.89, MFR0, viscosity of 5 mass% toluene solution 40 mPa · s ( 30 ° C)). Otherwise, the same treatment as in Example 5 was performed, but uniform kneading was not possible in the kneader kneading step, and the liquid paraffin was floated on the surface, and it was not possible to proceed to the subsequent step. This is considered due to the fact that the amount of oil absorption of the elastomer is small.
<Comparative Example 7>
In Example 5, a styrene elastomer containing ethylene-propylene (EP) with a styrene elastomer as an elastomer block (styrene content 35 mass%, specific gravity 0.92, MFR 0, viscosity of 5 mass% toluene solution 27 mPa · s ( 30 ° C)). Otherwise, the same treatment as in Example 5 was carried out, but due to the same phenomenon as in Comparative Example 6, it was determined that it was inappropriate as a liner material, and it was not possible to proceed to the subsequent step.
<Comparative Example 8>
A general-purpose epoxy phenol paint (epoxy phenol paint containing no polypropylene resin powder) was applied to the sealing surface of the cap body, and the cap was molded using the liner material of Example 1. Other than that, it processed similarly to Example 1 and performed the measurement of A hardness and tensile strength, and evaluation by the actual bottle test.

  The evaluation results are shown in Tables 1 and 2.

DESCRIPTION OF SYMBOLS 1 Twist cap main body 1a Sealing surface 2 Liner material 3 Bottle mouth 101 Drinking bottle cap main body 101a Sealing surface 102 Liner material 103 Bottle can mouth

Claims (4)

In the twist cap for food bottles, the liner material is molded flat on the sealing surface of the twist cap body, and the seal surface is only the top of the bottle mouth .
Containing a styrene elastomer (A), a polypropylene resin (B), liquid paraffin (C), and a lubricant (D);
The styrene elastomer (A) has a styrene content of 30 to 33% by mass, contains ethylene-ethylene-propylene (EEP) or ethylene-butylene (EB) as an elastomer block, 230 ° C., 2.16 kg / 10 min. The melt flow rate (MFR) at 0 is 0,
Styrenic elastomer (A) 15-30% by mass, polypropylene resin (B) 5-25% by mass, liquid paraffin (C) 45-65% by mass with respect to the total amount of (A), (B), (C). %, Lubricant (D) 1.5 to 10% by mass ,
As the lubricant (D), 0.5 to 2.0% by mass of higher fatty acid amide and 1.0 to 8.0% by mass of silicone oil are contained with respect to the total amount of (A), (B) and (C). A liner resin composition for a torsion cap. A twist cap for food bottling, comprising a step of applying and curing the liner cap resin material composition for a twist cap according to claim 1 on a sealing surface of a twist cap body for food bottling with a bottle mouth. Manufacturing method. The method for producing a twist cap for food bottling according to claim 2, wherein the liner material formed on the sealing surface of the twist cap body with the bottle mouth by the curing has a JISA hardness of 20 to 60. The twist cap for foodstuff bottling according to claim 3, wherein an epoxy phenol-based paint containing acid-modified polypropylene resin powder is applied to the sealing surface of the bottle mouth as the twist cap body. Manufacturing method.

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