JPH01193345A - Liner material - Google Patents

Abstract

PURPOSE:To provide a liner material having good stress cracking resistance and workability, by compounding an ethylene.alpha-olefin copolymer resin having a specific ethylene content with a specified amount of a lubricant. CONSTITUTION:A liner material comprises (A) 100 pts.wt. of an ethylene.alpha-olefin copolymer resin having an ethylene content of 80-97wt.%, preferably 85-95wt.% and a density of 0.925-0.895g/cm<3>, preferably 0.92-0.9g/cm<3>, (B) 0.01-5 pts.wt., preferably 0.05-3 pts.wt., of a lubricant, preferably the alkali metal, alkaline earth metal, zinc or aluminum salt of a higher fatty acid, higher fatty acid amide or silica and preferably further (C) 3-50 pts.wt., preferably 5-30 pts.wt., of an ethylene.alpha-olefin copolymer rubber having an ethylene content of 50-87mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liner material provided as a sealing material on the inner surface of a container lid such as a cap.

(Prior art and its problems) Conventionally, low density polyethylene (LDPE) has been used as a liner material.
) and straight-set low density polyethylene (LLDPE) are known.

However, liner materials made of these polyolefins still have a problem of insufficient stress cracking resistance.

One possible way to improve this stress cracking resistance is to use polyolefins with as low a melt flow rate as possible, but in this case, a new problem arises in that workability is significantly reduced. will occur.

That is, the liner material is applied by dropping the molten material onto the inner surface of the cap etc. and compressing it with a punch, etc. However, when using low density polyethylene etc., the molten material When dripping the liquid onto the inner surface of the cap, it becomes difficult to set the dropping position uniformly, and as a result, molding defects often occur.

Therefore, an object of the present invention is to provide a liner material with improved stress cracking resistance without impairing workability such as the above-mentioned molding defects.

(Means for Solving the Problems) The present inventors have discovered that an ethylene/α-olefin copolymer resin having an ethylene content in the range of 80 to 97% by weight,
It has been found that by adding a certain amount of lubricant to this, a liner material with good stress cracking resistance and workability can be obtained.

That is, the liner material of the present invention comprises: (A) an ethylene/α-olefin copolymer resin having an ethylene content in the range of 80 to 97% by weight; and (8) a lubricant; the lubricant is ethylene/α-olefin copolymer resin; α-olefin copolymer resin 10
It is blended at a ratio of 0.01 to 5 parts by weight per 0 parts by weight.

(Function) First, in the present invention, the ethylene/α-olefin copolymer resin acts to significantly improve stress cracking resistance.

As is clear from its ethylene content, this copolymer resin has a higher α-olefin comonomer component than conventional linear low density polyethylene (LLDPE), and therefore its density is 0.925 to 0.895 g/cm3. is in an extremely low range.

Incidentally, the ethylene content of LLDPE conventionally used for liner materials is about 97 to 99% by weight, and its density is in the range of 0.925 to 0.950 g/cm3. It is in a higher range than the density of the combined resin.

That is, by using such an ethylene/α-olefin copolymer resin, excellent stress cracking resistance is exhibited, as shown in the examples described later.

Further, according to the present invention, by blending a predetermined amount of a lubricant into the ethylene/α-olefin copolymer resin, workability is significantly improved as shown in the examples described later.

That is, FIG. 1 shows an apparatus for applying a liner material to a container such as a cap.
It is applied at the center of the inner surface. By compressing the resin thus applied to the inner surface of the cap 3 with a punch or the like, a liner is formed on the inner surface of the cap 3.

If a polyolefin with the lowest possible density is used as the liner material, the position of the resin 1 applied by the rotating blade 2 will be extremely inaccurate, resulting in molding defects etc. in the next compression molding process. This often occurred.

On the other hand, such problems did not occur with extremely high-density polyethylene and the like.

In the present invention, by blending a predetermined amount of lubricant into the low-density ethylene/α-olefin copolymer resin mentioned above, excellent workability similar to that of high-density polyethylene can be obtained, and the above-mentioned problems can be solved. It is solved by

Although the exact reason why workability such as molding defects is improved by adding a lubricant in this way is still unknown,
The present inventors estimate as follows.

That is, in low-density polyolefins such as LLDPE, side chains are bonded to a linearly long main chain, and the number of such side chains tends to increase as the density decreases.

In polyolefins with low density and good stress cracking resistance due to the presence of side chains, when applying this to the inner surface of the cap 3, the frictional force with the blade 2 is large. It is recognized that this causes the problem that the liquid is not dripped accurately.

Since high-density polyolefin has fewer side chains, there is no problem of friction with the blade, and the droplets are always dropped at a fixed position on the inner surface of the cap, so there is no problem with molding defects. be.

According to the present invention, by incorporating a lubricant, such friction with the blade is reduced, and workability is recognized to be significantly improved.

(Preferred embodiment of the invention) In the present invention, in such a copolymer resin, the α-olefin copolymerized with ethylene is , especially α-olefins having a carbon number of 3 to 8, specifically propylene, butene,
Hexene, octene, 4-methyl-1-pentene, etc. are used, and the ethylene content is 80 to 97% by weight, especially 8
It ranges from 5 to 95% by weight.

If the ethylene content exceeds the above range, the density will increase and the stress cracking resistance will decrease; if it is less, the heat resistance and workability will decrease, and this will also be disadvantageous in terms of cost.

In addition, this copolymer resin has a density (JIS K6760) of 0.925 to 0.89587 cm3, especially 0.920 cm3, in relation to the ethylene content being within the above range.
It is in the range of 0.90087cm3 to 0.90087cm3.

Furthermore, among the ethylene/α-olefin copolymer resins mentioned above, the melt flow rate (A
STM D I238) is 0.5 to 253710
Those within the range m1n are preferably used.

(B) Lubricants As the lubricants used in the present invention, those known per se, such as the following, are used.

1. Fatty acids, fatty alcohols Higher fatty acids Fatty acids obtained from animal or vegetable oils and hydrogenated fatty acids with 12 to 22 carbon atoms Hydroxystearic acid Straight chain aliphatic-hydric alcohols Animal or vegetable Products with 12 or more carbon atoms obtained by reducing fats and oils or their fatty acid esters or decomposing and distilling natural waxes, tridecyl alcohol 2, polyethylene glycols with a molecular weight of 200 to 9,500 polypropylene glycols with a molecular weight of 1000 or more polyoxypropylene -Polyoxyethylene-block polymer having a molecular weight of 1900 to 9000 3, amide, amine.

Higher fatty acid amide oleyl palmitamide stearyl erucamide 2 stearomide ethyl stearate ethylene bis fatty acid amide NN' oleoyl stearyl ethylene diamine NN'
Bis(2hydroxyethyl)alkyl(012~Cl
8) Amide NN' bis(hydroxyethyl) lauroamide N alkyl (C+a to C+a) distearic acid ester of oleic acid fatty acid jetanolamine di(hydroxyethyl) diethylenetriamine monoacetate 4, -hydric, polyhydric alcohol fatty acid ester of stearate n-butyl Hydrogenated rosin methyl ester Dibutyl sepatate (n-butyl) Dioctyl sepatate (2-ethylhexyl, n-octyl) glycerin fatty acid ester glyceryl lactostefryl Stearate ester of pentaerythritol Pentaerythritol tetra Stearate sorbitan fatty acid ester polyethylene glycol fatty acid ester polyethylene glycol monostearate polyethylene glycol dilaurate polyethylene glycol monooleate polyethylene glycol dioleate polyethylene glycol coconut fatty acid ester polyethylene glycol tall oil fatty acid ester entadiol montanate ester 1.3 butanediol montanate ester Diethylene glycol stearate ester Propylene glycol fatty acid ester 5, triglycerides, waxes Hydrogenated edible oils Cottonseed oil and other edible oils 12-Glycerin ester of hydroxystearic acid Hydrogenated fish oil Beef tallow Sparm acetiwax Montan wax Carnauba wax Beeswax M-aliphatic Alcohol and aliphatic saturated acid ester Examples: Hydrogenated whale oil lauryl stearate, stearyl stearate> Lanolin 6, Salts of higher fatty acids with alkali metals, alkaline earth metals, zinc and aluminum (metallic soaps) 7. Silicone oil This invention Of the above-mentioned lubricants, salts of higher fatty acids of alkali metals, alkaline earth metals, zinc and aluminum, higher fatty acid amides and silicone oils are particularly preferably used.

These lubricants may be used alone or in combination, but the blending amount is 100% of the ethylene/α-olefin copolymer resin.
0.0 per part by weight! 5 parts by weight, especially 0.05 to 3 parts by weight
The range is in parts by weight.

If the amount is less than the above range, the desired workability improvement effect will not be achieved, and if it is in a larger amount, it will have a negative effect on the stress cracking resistance and sealing properties of the liner material.

Other Compounding Agents In the present invention, in addition to the above components, 3 to 50 parts by weight, particularly 5 to 30 parts by weight of ethylene/α-olefin copolymer rubber is added per 100 parts by weight of the ethylene α-olefin copolymer resin. In order to further improve the stress cracking resistance, it is preferable to mix the resin at a ratio of .

This rubber component is not only completely amorphous but also X-
Also included are polymers with a low crystallinity of 15% or less as measured by linear diffraction.

This ethylene/α-olefin copolymer rubber contains ethylene and α-olefin, such as propylene, 1-butene, 1
-α with 3 to 10 carbon atoms such as pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc.
- A copolymer with one or more olefins.

The ethylene content is usually 50 to 87 mol%, preferably 63 to 82 mol%, and the intrinsic viscosity in a decahydronaphthalene solution at 135°C is 0.5 to 3.0.
dj2/g, particularly those in the range of 1.5d12/g are preferably used.

Furthermore, this ethylene/α-olefin copolymer rubber has the following properties:
One or more polyene components may be included.

Specifically, the polyene component includes 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-hebutadiene, 7-methyl-1,6- quenched nonconjugated dienes, such as octadiene,
Cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbornene,
5-ethylidene-2-norbornene, 5-methylene-2
-Norbornene, cyclic non-conjugated dienes such as 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isobrobenyl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethynelidene-3-isopropylene Typical examples include trienes such as lydene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1,3.7-octatriene, and 1,4.9-decatriene. Suitable polyenes are cyclic nonconjugated dienes and 1,4-hexadiene, especially dicyclopentadiene or 5-ethylidene-2-norbornene.

These polyene components are copolymerized so that the resulting copolymer has an iodine value of at most 30, preferably 20 or less.

Furthermore, the liner material of the present invention may contain various compounding agents known per se, such as fillers and antioxidants, in amounts that do not impair its properties.

(Example) An extruder was used using an ethylene/α-olefin copolymer resin, a lubricant (higher fatty acid metal salt), and a blend material (ethylene/boropyrene copolymer rubber) in the proportions shown in Table 1. An in-shell mold machine for forming a cap liner produces a 28mm aluminum plate with a thickness of 0.23m.
A liner was molded into the shell of the P cap.

The molding conditions were as follows.

Extruder (screw type, full flight) Screw diameter 40φ L/, 24) CR30 Rotation speed 60 rpm Extruder set temperature C, 170-220℃ C2180-240℃ F 180-260℃ Cap production 700 pieces/ Weight of liner: 350 mg Each liner was tested for workability, stress cracking resistance, and sealing properties, and the results are shown in Table 1.

Workability was determined by randomly extracting 500 trial caps, examining the liner shape, determining that workability was good if a predetermined liner shape was obtained, and examining the defective rate.

For the stress cracking resistance test, cut the side of the sample cap and hold it 180° from the center with the liner outside.
0.1 of surfactant (product name: Liponox)
% solution and left in a 50° C. thermostat to examine the occurrence of cracks in the liner. The number of preparations was 50 each, and the time (rs.) until cracks appeared in half of them was investigated.

Sealing performance was determined by filling a bottle (containing 300 mfl) with hot water at 95°C with a test cap, dropping it upside down from a height of 50cm on a steel plate at an angle of 20° for one day and night, and then measuring the internal pressure to see if there was any leakage. I looked into it.

Table 1 *Ethylene content of ethylene/α-olefin copolymer resin.

[Brief explanation of the drawing]

FIG. 1 shows an apparatus for applying liner material to a cap. 1...Extruded resin 2...Rotating blade 3...Cap Patent applicant: Nippon Crown Cork Co., Ltd., 2nd attorney, Yukio Shoko, patent attorney Figure 1

Claims (4)

[Claims] (1) Consisting of (A) an ethylene/α-olefin copolymer resin having an ethylene content in the range of 80 to 97% by weight, and (B) a lubricant, the lubricant being an ethylene/α-olefin copolymer resin. A liner material characterized in that the liner material is blended in a proportion of 0.01 to 5 parts by weight per 100 parts by weight of the combined resin. (2) Ethylene/α-olefin copolymer resin (A) 1
Ethylene at a ratio of 3 to 50 parts by weight per 00 parts by weight.
Claim 1 wherein α-olefin copolymer rubber is blended.
Liner material listed. (3) The ethylene/α-olefin copolymer resin is
The liner material of claim 1 having a density of 0.925 to 0.895 g/cm^3. (4) The liner material according to claim 1, wherein the lubricant is a higher fatty acid metal salt, silicone oil, or fatty acid amide.