JP2000168824A - Resin composition for cap liner material and cap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cap liner material composition wherein an amount of a slip agent to be added to the composition can be reduced and disturbance to a flavor of bottle contents such as a beverage can be prevented by providing a cap liner which is excellent in surface slipperiness. SOLUTION: This cap liner material composition comprises (A) 15 to 80 wt.% of a polyethylene-based resin, (B) 10 to 60 wt.% of hydrogen added styrene-conjugated diene block copolymer rubber with solution viscosity of 100 to 10,000 mPa.s and (c) 10 to 50 wt.% of liquid paraffin with viscosity of 20 to 550 mm2/S (40 deg.C), wherein the composition whose morphology is such that the polyethylene-based resin (A) is a matrix is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for a cap liner material and a cap, and more particularly to an amount of a slip agent to be added to a composition for a cap liner material due to the excellent surface slip property of the cap liner. Can be reduced, and the inhibition of flavor by the slip agent on the contents of the bottle such as drinking water can be prevented.

Moreover, by using an appropriate hydrogenated styrene-conjugated diene block copolymer rubber, heat resistance,
It has high impact resistance and excellent sealing properties.

[0003] Due to such properties, the composition of the present invention prevents the flavor of the contents of the bottle from being impaired, and also prevents leakage during the transportation, such as vibration, impact and dropping of the beverage bottle, and is useful. It is.

[0004]

2. Description of the Related Art In general, as a material used for a cap liner material of a container cap, a composition such as a hydrogenated styrene-conjugated diene block copolymer rubber and liquid paraffin (Japanese Patent Publication No. 6-8860) is used for a polypropylene resin.
No. 8) has been suitably used.

When observing the morphology of this composition, a polypropylene resin is generally used as a matrix, and when used as a cap liner, the resin composition on the surface of the cap liner is mostly a polypropylene resin.

[0006] Polypropylene resins have poor surface slip properties, and it has been necessary to add a considerable amount of a slip agent to a composition for a cap liner material in order to optimize the torque when opening the cap.

As a result, there has been a problem that a serious flavor inhibition is caused by the slip agent on the contents of the bottle, and a so-called wax float is generated in which the slip agent bleed out on the surface of the cap liner is mixed into the contents. .

The polypropylene resin is added in consideration of the adhesiveness of the cap liner to the resin cap (main material is a polypropylene resin). However, since the rigidity of the polypropylene resin is high, the cap liner is added. There is also a disadvantage that the flexibility required for the method is impaired.

Therefore, there has been a demand for a composition for a cap liner material which not only has heat resistance and impact resistance, which are essentially cap liner properties, but also prevents a bottle from impairing flavor.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and has a heat resistance and an impact resistance, and a cap opening torque with a low addition amount of a slip agent formulation. It is an object of the present invention to provide a composition for a cap liner material capable of optimizing the composition, and a cap provided with a cap liner made of the composition.

[0011]

The inventors of the present invention have conducted intensive studies with the aim of preventing the bottle contents from impairing the flavor and having excellent heat resistance and impact resistance. A resin for a cap liner material composed of a resin, a hydrogenated styrene-conjugated diene block copolymer rubber and liquid paraffin, and a matrix in the morphology of the composition is a polyethylene resin having excellent surface slip properties, The amount of the slip agent added to the composition for cap liner material can be reduced, preventing the inhibition of the flavor of the contents of the bottle, and even if the polyethylene resin is used as a matrix, the adhesion to the cap is a problem in actual use. In addition, they found that the invention was flexible, and completed the invention.

That is, in the present invention, (a) 15 to 80% by weight of a polyethylene resin, (b) solution viscosity (test method; Brookfield-type rotational viscosity measurement method, conditions; 10 wt% polymer concentration in toluene solution at 25 ° C.) 100-100
10 to 60% by weight of a hydrogenated styrene-conjugated diene block copolymer rubber of 00 mPa · s and (d) 20 to 55
0 mm ² / S (40 ° C.) viscosity (JIS K2283-
83) A composition for a cap liner material comprising 10 to 50% by weight of liquid paraffin having a morphology of polyethylene resin (a) serving as a matrix. It is.

The polyethylene resin (A) used in the present invention includes a homopolymer of ethylene produced by a method such as a high-pressure method, a medium-pressure method or a low-pressure method, and ethylene and at least one other α-type. It is a copolymer with an olefin or a copolymer of ethylene with a vinyl ester compound such as vinyl acetate. Here, the α-olefin used for copolymerization with ethylene includes 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene,
Onene and 4-methyl-1-hexene.

Further, one or more blends of an ethylene homopolymer and an ethylene / α-olefin copolymer and modified products thereof with a carboxylic acid derivative or an epoxy derivative may be used. .

Melt flow rate of polyethylene resin (JIS K7210-76; 190 ° C., 2.16 kg
Load) is 0.01 to 120 g / 10 min, density (J
ISK6760-81) is 0.850-0.970 g
/ Cm ³ is preferable in terms of mechanical strength and fluidity.

Further, the polyethylene resin (a) has a density (JI) produced by a low-pressure method because the resulting heat resistant composition of the cap liner material is more excellent.
SK6760-81) 0.940~0.970g / cm ³
Is preferred. Further, a polyethylene-based resin having a property that the monodispersity (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is in the range of 1.5 to 3.0 is used. preferable. A polyethylene resin having this property can be produced using a metallocene catalyst having at least one cyclopentadienyl group or substituted cyclopentadienyl group on a transition metal such as zirconium, hafnium, or titanium.

The hydrogenated styrene-conjugated diene block copolymer rubber (b) used in the present invention has the following block structure: A: styrene polymer block, B: conjugated diene polymer block. Type A or AB
Mold and one or more blends. The hydrogenated product is obtained by hydrogenating a conjugated diene portion.

A hydrogenated styrene-butadiene block copolymer rubber (b) is generally a hydrogenated styrene-butadiene block copolymer rubber having a butadiene polymer block in a conjugated diene polymer block and an isoprene polymer. What is called a hydrogenated styrene-isoprene block copolymer rubber using blocks is preferably used, and the conjugated diene polymer block may be a block of butadiene and isoprene or a random polymer block.

Here, styrene monomers used in the styrene polymer block include styrene, t-butylstyrene, α-methylstyrene, p-methylstyrene,
Divinylbenzene, 1,1-diphenylstyrene, N,
Examples thereof include N-diethyl-p-aminoethylstyrene and N, N-vinylpyridine, and styrene and α-methylstyrene are particularly preferable. The solution viscosity of the hydrogenated styrene-conjugated diene block copolymer rubber (b) (test method; Brookfield-type rotational viscosity measurement method, conditions; 10 wt% polymer concentration in toluene solution at 25 ° C) is 100 to 10
000 mPa · s, preferably 200 to 6000 m
If it is less than 100 mPa · s, the heat resistance will be poor. If it exceeds 10,000 mPa · s, the fluidity will be significantly reduced, and the moldability of the cap liner will be poor.

The test method of the solution viscosity will be described in detail.
A sample of a hydrogenated styrene-conjugated diene block copolymer rubber (60 ± 0.2 g) was dissolved in toluene (540 g ± 0.2 g).
The solution viscosity is measured in an environment of ± 0.5 ° C.

Examples of hydrogenated styrene-butadiene block copolymer rubber include “Septon” (SEBS manufactured by Kuraray Co., Ltd.), “Clayton G” (SEBS, SEBS / SEB blend made by Shell Japan Co., Ltd.), And the trade name “TUFTEC” (SEBS manufactured by Asahi Kasei Kogyo Co., Ltd.). As the hydrogenated styrene-isoprene block copolymer rubber, the trade name “Septon” (SEP, SEPS manufactured by Kuraray Co., Ltd.) and the trade name "Clayton G" (SE manufactured by Shell Japan Co., Ltd.)
P) and the like.

Liquid paraffin used in the present invention (c)
Is composed of a saturated hydrocarbon purified by removing impurities such as aromatic hydrocarbons and sulfur compounds contained in a petroleum lubricating oil fraction.

The viscosity of the liquid paraffin is 30 to 550 m
m ² / S (40 ° C.), preferably 50 to 300 mm ² /
If the S (40 ° C.) is less than 30 mm ² / S, the heat resistance is low and the wax has a low viscosity, so that the liquid paraffin is eluted from the cap liner material into the contents, causing a wax float phenomenon, which is poor, and exceeding 550 mm ² / S. In addition, the fluidity of the composition for a cap liner material is insufficient, resulting in poor processability.

Examples of the liquid paraffin include “Christol” (trade name of liquid paraffin manufactured by Esso Oil Co., Ltd.) and “Moresco White” (trade name of liquid paraffin manufactured by Matsumura Petroleum Institute Co., Ltd.).
In the composition for a cap liner material of the present invention, the polyethylene resin (A) is 15 to 8;
0% by weight, preferably 20 to 60% by weight, and hydrogenated styrene-conjugated diene block copolymer rubber (b) is 10% by weight.
-60% by weight, preferably 15-40% by weight, and liquid paraffin (c) is 10-50% by weight, preferably
It is composed of 15 to 40% by weight.

When the content of the polyethylene resin (a) is less than 15% by weight, the slipperiness of the surface of the cap liner is inferior.
If it exceeds 0% by weight, it becomes hard and lacks elasticity.

When the amount of the hydrogenated styrene-conjugated diene block copolymer rubber (b) is less than 10% by weight, the effect of imparting elasticity is small, and when the amount exceeds 60% by weight, the fluidity is remarkably reduced and the fluidity is poor.

If the content of liquid paraffin (c) is less than 10% by weight, fluidity and elasticity are lacking, and if it exceeds 50% by weight, outflow of liquid paraffin to the contents is liable to occur, which is not good. In order to obtain the composition for a cap liner material and the cap molded product of the present invention, the polyethylene resin (a), the hydrogenated styrene-conjugated diene block copolymer rubber (b), and the liquid paraffin (d) are used as described above. Various methods known in the art, such as Henschel mixer, V-
After mixing with a blender, ribbon blender, tumbler blender, etc., melt kneading with a single screw extruder, twin screw extruder, kneader, Banbury mixer, etc. Or, using an auto feeder method, create a sheet of an arbitrary thickness with a sheet forming machine or the like, punch it into an arbitrary shape, paste it on the top surface inside the cap using an adhesive, or melt / cut the punched one. After melting and kneading with a sheet punching method or extruder, etc., which is melted and bonded to the top surface inside the cap, cut out a fixed amount in the molten state on the top surface inside the cap, and immediately press the cut out composition Cooling and forming into a cap liner shape by direct extrusion press method (in-shell mold method) The method of the cap liner material composition and the composition obtain cap equipped as a cap liner Ri is preferably used.

In the composition for a cap liner material of the present invention, a thermoplastic resin, a thermoplastic elastomer, a heat stabilizer, a weather stabilizer, an antistatic agent, a slip agent, a surfactant, an antifogging agent, Drops, nucleating agents, pigments, dyes, silica,
Inorganic or organic additives such as talc, mica, carbon, calcium carbonate, magnesium carbonate, metal stearate, wood flour, cork powder, cellulose powder, and the like, even if they are blended within a range that does not impair the purpose of the present invention. good.

The same kind of components as the resin cap body, for example, polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polystyrene, acrylonitrile-styrene-butadiene copolymer (ABS), polyethylene naphthalate, polycarbonate, etc. These blends were used to improve the adhesion to the cap.
It is preferable to add 1 to 5 parts by weight to 0 part by weight.

A slip agent is often used to adjust the cap opening torque. Particularly, higher fatty acid amides, higher fatty acids, glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, higher alcohol fatty acid esters, and ethylene bis A higher fatty acid amide or the like is used, and preferably, a higher fatty acid amide is used. Specifically, caprylic amide, capric amide, lauric amide, myristic amide, palmitic amide, stearic amide, arachidic amide, behenic amide, oleic amide, erucic amide, linoleic amide, Linolenic acid amide is mentioned, and stearic acid amide, oleic acid amide and erucic acid amide are preferable.

The characteristic of the composition for a cap liner material of the present invention is a mixed system of a polyethylene resin, a hydrogenated styrene-conjugated diene block copolymer rubber and a liquid paraffin. Is a method of improving the slip property of the surface of the cap liner by using a matrix structure to prevent the inhibition of flavor, which is not present in conventional compositions for cap liners, and for heat-resistant and impact-resistant cap liners It is a composition.

[0032]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist of the present invention.

The test and measurement methods used in the present invention are as follows.

An in-shell mold method generally used for cap molding was employed as a method for preparing the following test cap samples. Specifically, the material is melt-extruded with an extruder at a resin temperature of 200 ° C., and a fixed amount (about 300 mg)
Was hot-cut and dropped into a shell of a 28 mmφ polypropylene cap. Immediately, the sample was pressurized and cooled with a pressing die, and adjusted to a liner shape to produce a sample cap.

A 500 ml PET bottle was filled with 500 ml of distilled water at 80 ° C., and the sample cap prepared by the in-shell mold method was used to tighten the cap with a torque of 15 kg-cm. Thereafter, hot water at 90 ° C. was showered from the top surface of the cap for 5 minutes and sufficiently cooled to room temperature to obtain a test PET bottle.

<Confirmation of Matrix Components> The sample cap is cut vertically (about -120 ° C. with liquid nitrogen) using an ultramicrotome to a thickness of about 0.1 μm. The cut sample was stained with ruthenium tetroxide to obtain a sample for observing matrix components. The matrix component of the sample was confirmed by a transmission electron microscope (acceleration voltage: 200 kV).

<Drop test of water-containing bottle> As a test for comparing the heat resistance and the impact resistance of the composition for a cap liner material, the following test method was carried out.

Twenty dummy bottles (500 ml of water simply put into a bottle similar to a test PET bottle and a cap tightly wound) are placed in a carton case made of 24 pieces (4 pieces × 6 steps) made of cardboard. Only the upper four bottles were filled with test PET bottles with sample caps wrapped around.

The carton case was placed so that four bottles made of test PET were at the upper stage, and the carton case was gradually tilted down by its own weight and dropped so that the top surface of the cap became an impact surface.

The test PET bottles were repeatedly dropped until the liquid leaked, and the number of drops of the test PET bottles was taken as the number of drops, and the bottle was taken out of the carton case and replaced with a dummy bottle. This test was repeated until all the test PET bottles leaked. There is no problem if the number of drops is 30 or more in actual use. (However, the maximum number of drops was set to 50.) <Measurement of cap opening torque>
Immediately after storage at ℃ for 1 week, the cap opening torque of the cap wound around the test PET bottle was measured immediately by a cap opening torque measuring instrument (TNK-60B manufactured by Shinpo Kogyo Co., Ltd.). In addition, the measured value of the cap opening torque is an average value of ten test PET bottles.

The proper value of the cap opening torque is 8
１５15 kg-cm.

<Content Flavor Test> A test PET bottle was laid on its side, and distilled water after storage at 50 ° C. for 2 weeks was subjected to a sensory test of human smell and taste to change the flavor with distilled water before filling. Watched. The test was performed by indicating ○ for no change in flavor, △ for slight change, and x for clear change. In addition, it carried out by the sensory test by five persons. Then, as a comprehensive evaluation, those having no flavor inhibition were evaluated as ○ (in the case where there was no x, two or less, and Δ was other than 、), and some flavor inhibition was observed. For △
(When there is no x, three or more and the others are o), x (when there is at least one x) is displayed.

Example 1 Polyethylene resin (manufactured by Tosoh Corporation, trade name: Petrocene 203; branched low-density polyethylene, melt flow rate (JIS K7210-76; 190 ° C., 2.
8g / 10min, density (JIS K6)
760-81) 30% by weight of 0.919 g / cm ³ (hereinafter referred to as PE-1), hydrogenated styrene-conjugated diene block copolymer rubber (manufactured by Shell Japan K.K .: trade name Clayton G1651; solution viscosity (polymer concentration) 10
wt% toluene solution, 25 ° C.) 1000 mPa · s (hereinafter referred to as SBC-1) 40% by weight and liquid paraffin (manufactured by Esso Oil Co., Ltd .: trade name Christol J-2)
62; viscosity (JIS K2283-83) 51 mm ³ /
S (40 ° C., hereinafter referred to as flow para-1) 30% by weight of 1
After adding 0.3 part by weight of erucic acid amide to 00 parts by weight and mixing with a tumbler blender for 15 minutes, L / D =
The composition was obtained by melt-kneading and granulating at a resin temperature of 210 ° C. with a twin screw extruder manufactured by Toshiba Machine Co., Ltd. of 36 mm and 57 mmφ. Using the composition, a matrix component was confirmed, a drop test of a water-filled bottle, a cap opening torque measurement, and a content flavor test were performed. The test results are shown in Table 1.

Example 2 In Example 1, PE-1 was replaced by a polyethylene resin (manufactured by Tosoh Corporation, trade name: Nipolon Hard 5700;
Melt flow rate (JIS K7210-76; 19
The composition was changed to 1.0 g / 10 min (0 ° C., 2.16 kg load), 1.0 g / 10 min, density (JIS K6760-81) 0.953 g / cm ³ , hereinafter referred to as PE-2). Table 1 shows the test results.

Example 3 In Example 1, PE-1 was replaced with a polyethylene resin (manufactured by Dow Chemical Japan Co., Ltd .; trade name: Affinity P).
T1450; melt flow rate (JIS K7210)
−76; 190 ° C., 2.16 kg load) 7.5 g / 10
min, density (JIS K6760-81) 0.902
g / cm ³ , Mw / Mn 1.9, hereinafter referred to as PE-3)
And the composition was obtained as in Example 1. Table 1 shows the test results.

Example 4 In Example 2, 50% by weight of PE-2 and SEBS-
1 (30% by weight) and Flow Para-1 (20% by weight) to 100 parts by weight of polypropylene (manufactured by Chisso Corporation: trade name: Chisso Polypro K1800, hereinafter referred to as PP-1)
4 parts by weight and erucic acid amide 0.3 parts by weight,
A composition was obtained as in Example 1. Table 1 shows the test results.

Example 5 In Example 1, SBC-1 was replaced with a hydrogenated styrene-conjugated diene block copolymer rubber (manufactured by Kuraray Co., Ltd .; trade name: Septon 4055; solution viscosity (polymer concentration: 10 w
(t% toluene solution, 25 ° C.) 5800 mPa · s, hereinafter referred to as SBC-2), and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 1 In Example 1, PE-2 was replaced with polypropylene (manufactured by Chisso Corporation; trade name: Chisso Polypro K1011;
P-2), and a composition was obtained as in Example 1. Table 1 shows the test results.

Comparative Example 2 A composition was obtained in the same manner as in Example 1 except that the amount of erucic acid amide was changed to 0.5 part by weight. Table 1 shows the test results.

Comparative Example 3 In Example 2, SBC-1 was replaced with a hydrogenated styrene-conjugated diene block copolymer rubber (manufactured by Shell Japan Co., Ltd., trade name: Clayton G1657; solution viscosity (polymer concentration: 10 wt% toluene solution, 25 ° C.) ) <20 mP
a · s, hereinafter referred to as SBC-3), and a composition was obtained as in Example 1. Table 1 shows the test results.

[0051]

[Table 1]

[0052]

EFFECT OF THE INVENTION The composition for a cap liner material of the present invention does not exist in a conventionally known composition for a cap liner material.
Excellent heat resistance, impact resistance, and excellent surface slip property of the cap liner reduce the amount of slip agent that is usually added to the cap liner, thereby preventing the flavor of the contents from being hindered. Let
Useful.

Claims (5)

[Claims] (1) polyethylene resin 15 to 80% by weight, (b) solution viscosity (test method; Brookfield-type rotational viscosity measurement method, condition; polymer concentration 10 wt% toluene solution, 25 ° C.) 100 to 10,000 mPa Hydrogenated styrene-conjugated diene block copolymer rubber 10
６０60% by weight and (c) 20-550 mm ² / S (40
C) having a viscosity (JIS K2283-83) of 10 to 50% by weight of a liquid paraffin, wherein the morphology of the composition is as follows:
A composition for a cap liner material, wherein the composition has a structure in which the polyethylene resin (a) serves as a matrix. 2. A composition for a cap liner material for a resin cap, wherein 1 to 5 parts by weight of a resin component of the same type as the cap body is added to 100 parts by weight of the composition according to claim 1. 3. The density of the polyethylene resin (a) is 0.9.
The composition for a cap liner material according to claim 1, wherein the composition is 40 to 0.965 g / cm ³ . 4. The polyethylene resin (a) has a monodispersity (weight average molecular weight / number average molecular weight) in gel permeation chromatography measurement of 1.5 to 3.0. The composition for a cap liner material according to any one of claims 1 to 3. 5. A cap provided with a cap liner comprising the composition for a cap liner material according to claim 1.