JPH03134085A - Liner for screw type metallic cap - Google Patents

Abstract

PURPOSE:To obtain a liner for a screw type metallic cap with improved sealing properties, shelf stability and plug-opening properties by compounding each specified ethylene resin and hydrogenated block copolymerized elastomer and a higher fatty acid amide. CONSTITUTION:A liner prepared by using a sheet made from a compsn. consisting of 60-80 wt.% ethylene resin (A), 40-20 wt.% hydrogenated block copolymerized elastomer (B) and 0.1-0.5 pt.wt. higher fatty acid amide (C) based on 100 pts.wt. in total of the ingredients A and B wherein the vinyl acetate content of the ingredient A is 3-10 pts.wt.; the ingredient B is a hydrogenated block copolymer consisting of a polymer block with styrene as the main ingredient and a polymer with a hydrogenated butadiene as the main ingredient; the ingredient C is an 8-22C fatty acid amide compd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a liner for a cap, particularly a liner for a screw-type metal cap, which has excellent preservability of contents and is easy to open during practical use.

More specifically, without sacrificing the excellent flexibility, food hygiene, moldability, etc. of ethylene resin, it can be used to improve sealability, preservability, and practical use of beverages, especially soft drinks, beer, and other high-pressure contents. This invention relates to a liner for a screw-type metal cap that has significantly improved opening performance.

[Conventional technology]

Conventionally, cork, soft PVC, olefin resins, especially ethylene resins, and the like have been used as liners for bottle caps. Among these, cork liners are preferred for their rebound resilience and are a natural material that has been used for a long time, but there are large differences in quality, making the quality unstable, producing cork dust, and being relatively expensive. etc.,
In recent years, liners such as soft PVC and olefin resins have been giving up their position.

However, although soft PVC liners are also flexible and have excellent sealing properties, in recent years, due to hygienic issues such as plasticizers and vinyl chloride monomers, there has been a shift to olefin resins, which have excellent hygienic properties.

Ethylene resin is widely used for the olefin resin liner, which is inherently flexible, but it does not have sufficient sealing properties against defects such as poor shape at the mouth of the bottle and scratches and chips in the rim. On the other hand, the internal pressure of the contents may decrease during long-term storage, or on the other hand, even if sufficient sealing performance has been obtained, the original function such as opening with a screw cap etc. There were problems such as not being able to

(Problems to be Solved by the Invention) The problem of the present invention is to solve the above problems, that is, to improve the properties of ethylene resin, especially without impairing the excellent moldability and food hygiene of ethylene resin. An object of the present invention is to provide a liner for a screw-type metal cap that has improved sealing performance, storage stability, and opening performance that cannot be achieved by flexibility alone.

[Means to solve the problem]

The present inventors have conducted repeated studies to solve these problems, and as a result, have found that the problems can be solved by using a liner made of a specific ethylene polymer composition, and have completed the present invention.

That is, the present invention has (A) an ethylene resin of 60 to 80 ff.
(hereinafter referred to as wt%), (B) 40 to 20 wt% of hydrogenated block copolymer elastomer, and (C) higher fatty acid amide based on 100 parts by weight of (A) and (B) in total. A composition comprising 0.1 to 0.5 parts by weight,
Component (A) consists of low density polyethylene and/or ethylene-vinyl acetate copolymer, and the vinyl acetate content in component (A) is 3 to 10 wt%, and component (B) consists of a polymer mainly composed of styrene. It is a hydrogenated block copolymer consisting of a combined block and a polymer block mainly composed of hydrogenated butadiene, and the component (C) has 8 to 22 carbon atoms.
The present invention provides a liner to be installed inside a screw-type metal cap, which is characterized by using a sheet made of a composition that is an amide compound of fatty acids.

The low density polyethylene used in the present invention is JIS: 674
8, the density is preferably 0.910 or more and less than 0.930, and preferably a density of 0.920 JX or less is preferable from the viewpoint of flexibility to provide sealing performance. Furthermore, the ethylene resin (^) made of polyethylene and/or edylene-vinyl acetate copolymer contains 3 to 10 w of vinyl acetate.
t%, preferably 4 to 8 wt%.

If the content exceeds 10 wt%, the odor may be disliked depending on the content, and the content may be too flexible, have poor load-bearing properties, and become subject to large deformation, which may result in insufficient sealing performance or a decline in long-term storage stability. So I don't like it. On the other hand, the content is 3w
If it is less than t%, it is difficult to obtain the desired performance.

The hydrogenated product of the styrene-butadiene block copolymer has a styrene content of 10 to 45 wt%, a hydrogenation rate of 80% or more, preferably 90% or more, and in the present polymer composition, The blending ratio is 20 to 40 wt%. 4
If it exceeds 0 wt%, it will have high rubber elasticity, which is preferable for long-term storage, but it will also cause large shear deformation, making it difficult to open the screw-type cap. On the other hand, if it is less than 20 wt%, it is difficult to achieve sufficient sealing performance.

The higher fatty acid amide preferably consists of one or more amide compounds of fatty acids having 8 to 22 carbon atoms, more preferably one or more amide compounds between unsaturated fats having 16 to 22 carbon atoms, and comprises the above polymer (A ) and (B) in an amount of 0.1 to 0.5 mm part, preferably 0.2 to 0.4 part by weight, per 100 parts by weight of the mixture.

If it is less than 0.1 part by weight, sufficient slippage will not be obtained and the opening will tend to be insufficient, and if it exceeds 0.5 part by weight, it will noticeably bleed onto the liner surface and cause problems such as contamination with the contents. Possible and undesirable.

Additionally, in the above composition, commonly used additives such as colorants, stabilizers, modifiers, processability improvers, etc. may be added to the extent that the properties of the polymer composition of the present invention are not impaired.

To obtain the polymer composition used in the liner of the present invention, (
^) Ethylene resin, (B) styrene-butadiene block copolymer hydrogenated product, and (C) higher fatty acid amide may be uniformly mixed.

Examples of the mixing method include mixing with a commonly used mixer such as a Henschel mixer or drum blender, and uniformly mixing using a melt kneader such as an extruder, Banbury mixer, or roll mill. The liner is generally formed into a plate shape using a sheet forming device such as an extruder or a roll mill, and then cut or punched according to the size and shape of the metal cap. The thickness is selected depending on the function of the cap, but is in the range of 0.5 to 2 m.

(Effects of the Invention) By using the liner of the present invention, excellent performance in sealing and preservability of beverages with internal pressure such as carbon dioxide gas can be achieved without impairing the excellent moldability and food hygiene properties of ethylene resin. It has now become possible to provide a cap that exhibits excellent performance and is easy to open during practical use.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 9, Comparative Examples 1 to 5 Using the polymers and additives shown in Table 2, the following (1) to
The composition shown in Table 1 was prepared by the method shown in (3), and a liner was manufactured using this and was attached to a cap. This product was evaluated by the method shown in (4) below. The results are shown in Table 3.

① L makeup sole belly 1 1 Each composition shown in Table 1 was premixed, melted and kneaded using an extruder, and extruded into pellets (3φ×3Lml) to produce pellets.

The preliminary mixing was performed at room temperature using a drum blender for 15 minutes. In addition, melt kneading was performed using a 40axφ extrusion 11 (
L/D28. Full flight screw) at 200℃
Melt extrusion was performed.

The above composition (pellets) was extruded into a 40sφ IEI (L/D
28. A sheet with a thickness of 0.8 m was molded at 200° C. using a sheet molding device consisting of a full-flight screw. Next, this is 33! IJ! The hitting method was done using an nφ cutting blade.

(3) Cap (33mm diameter, 20m diameter screw type) The above liner was attached to the inside surface of the cap by heat-pressing it at 200'C for 1 minute. Adhesive properties were given to the inner surface of the cap in advance. A cap coated with an ethylene oxide modified epoxy hot melt material was used.

Danri Rekikan Katsushika (a) Preservation Sensory Test 1 ~ “Arihi Beer” (Arihi Beer) in a clean glass container
(manufactured by Co., Ltd.) and sealed using an AI screw cap fitted with a liner made of the polymer composition shown in Table 1, and stored in an inverted state at 25°C. Preservation 14
After a day, the beer was opened, and 12 panelists conducted a discrimination test to determine whether it was different from Asahi Beer (using a low-density polyethylene liner), which had been stored at the same time.

The test result is "significant difference" with X, "no significant difference" with ○,
``It cannot be said that there is a significant difference, but there is some sense of difference'' is indicated by Δ.

(b) Sealing and storage test (a) Fill a 2N glass bottle with 100 cc and fill it with carbonated water.
Njf, seal with side torque 38 Kyr-cm.

The carbonated water used was one that dissolved 2.5 times the volume of carbon dioxide at 23°C as compared to the same volume of water.

(b) The glass container sample in the state of (a) was heated to 60℃ for 1 hour.
Heat for 0 minutes and check for gas leaks. Further, leave it at 40°C for 7 days and check for gas leaks.

(C) The glass bottle mentioned above has a width of 2 to 3M in the circumferential direction and a depth in the radial direction on the outer edge of the bottle mouth, assuming that the shape of the bottle mouth is defective and the same product is scratched or chipped, which is unavoidable in practical use. A total of 10 glass bottles with chips in the range of 1 to 2 holes were selected and used for this evaluation.

(d) The evaluation results were displayed as follows.

O: All or most do not leak (leak rate 0/10 to 1/10) X: All or most leak (leak rate 6 to 10/10) Δ: Intermediate between the above (leak rate 2 to 5/10) 10) (c) Openability test The glass bottle sample from (b) (a) above was heated in hot water at 60°C for 10 minutes, then cooled to room temperature, and stored at 5°C for 14 days at 1.3.7°. Open each bottle with a torque meter and measure the opening torque at that time.

Preferred torque is 5 to 20 to 9 f-cm and 5 Ng
If it is less than f-cm, it may not be possible to maintain sufficient honeymoon properties for practical purposes, so it should be set to 20! When the torque exceeds 1f-r:m, opening becomes difficult in proportion to the size of the torque.

This evaluation result is displayed as follows.

O: Torque tO ~ 16Ngf-C/71 X:
Torque less than 5 Kif-cm and over 20 Klf-cm

Claims (1)

[Claims] 1. (A) 60-80% by weight of ethylene resin; (B) 40-2% hydrogenated block copolymer elastomer
0% by weight, and (C) a higher fatty acid amide in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the total amount of components (A) and (B), wherein the component (A) is consisting of low density polyethylene and/or ethylene-vinyl acetate copolymer, and the vinyl acetate content in the component (A) is 3 to 10% by weight, and the component (B) is a polymer block mainly composed of styrene. It is a hydrogenated block copolymer consisting of a polymer mainly composed of hydrogenated butadiene, and is characterized by using a sheet consisting of a composition in which the component (C) is an amide compound of a fatty acid having 8 to 22 carbon atoms. A liner installed inside a screw-on metal cap.