JPS62256836A - Material for packing of bottle cap or the like - Google Patents

Abstract

PURPOSE:To obtain a material for a packing of a bottle cap or the like, having elasticity and excellent heat resistance, by using a random copolymer of a 4-methyl-1-pentene of specified properties with a 3-7C alpha-olefin as the principal component. CONSTITUTION:A 4-methyl-1-pentene having a 4-methyl-1-pentene content of 40-80mol%, an m.p. of 140-220 deg.C, a softening point of 90-190 deg.C and a degree of crystallization in the range of 15-35% as determined by X-ray diffractometry is prepared. A random copolymer of this 4-methyl-1-pentene with a 3-7C alpha- olefin except 4-methyl-1-pentene (e.g., 1-hexane or 1-butene) is produced. The obtained random copolymer as the principal material is mixed with necessary additives such as a heat stabilizer, pigment, filler and blowing agent, and the obtained mixture is molded into any desired shape by, for example, extrusion to obtain the purpose material for a packing of a bottle cap or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a packing material that has elasticity and excellent heat resistance and is used for sealing containers such as bottle caps.

[Conventional technology]

Conventionally, Colfujisufu has been widely used as a packing material for bottle caps and the like because of its high elasticity, excellent airtightness, and good heat resistance. However, because corfujisufu is made from cork resin, it is expensive and the manufacturing process is complicated, so in recent years there has been a push to replace it with plastic. The packing material must (A) be highly elastic, (b) heat resistant (not deformed by boiling water at 100°C), and (c)
Performance requirements include: (d) not causing any problems in terms of food hygiene; (d) not discoloring or deteriorating the contents or giving a nasal smell; and (e) not causing dissolution, swelling, or deterioration due to the contents. .

Ethylene-vinyl acetate copolymer and ethylene-propylene rubber are soft plus Y-socks with good elasticity, but they are still unsatisfactory in terms of performance, especially heat resistance.

The plastics currently in practical use as packing materials are soft vinyl chloride resin and high-pressure low-density polyethylene, but soft vinyl chloride resin requires the use of a large amount of plasticizer, and high-pressure low-density polyethylene is It is difficult to heat treat because its heat resistance and elasticity are not very good.
It is necessary to increase the capping pressure when capping the subject.
This causes noise during capping, damage to the bottle, and other problems.

[Problem that the invention seeks to solve]

In view of this situation, the present inventor conducted various studies in order to obtain a packing agent that does not contain a large amount of plasticizer, has elasticity, and has excellent heat resistance. The present inventors have discovered that an olefin random copolymer has the above-mentioned properties, and have completed the present invention.

[Means for solving problems]

That is, the present invention has a 4-methyl-1-pentene content of 40 to 80 mol% and a melting point of 140 to 220°C.
4-methyl-1-pentene having a softening point of 90 to 190°C and a crystallinity of 15 to 35% by X-rays and a carbon number of 3 to 7 (provided that 4-methyl-1-
The present invention provides a packing agent for bottle caps, etc. that has elasticity and heat resistance (excluding pentene) and alpha-olefin (excluding pentene).

[Function] The 4-methyl-1-pentene/α-olefin random copolymer used in the present invention (hereinafter sometimes abbreviated to “random copolymer”) is a polymer having a 4-methyl-1-pentene content. 40 to 80 mol%, preferably 50 to 75 mol%, melting point 140 to 220°C, preferably 160°C
4-methyl-1-pentene having a softening point of 90 to 190°C, preferably 110 to 180°C and an X-ray crystallinity of 15 to 35%, preferably 20 to 30%. 3 to 7 carbon atoms
(However, 4-methyl-1-pentene is excluded) Random copolymer with α-olefin, usually decalin solvent 135
Intrinsic viscosity [η] at °C is 0.5 to 641/g
, preferably 1 to 5d! /g range.

Copolymers with a 4-methyl-1-pentene content of less than 40 mol% have low heat resistance, mechanical strength, and elastic modulus, while copolymers with a 4-methyl-1-pentene content of more than 80 mol% are too hard and have poor sealing properties. . The 4-methyl-1-pentene content in the present invention is '
This is a value measured by C-NMR method.

A copolymer having a melting point of less than 140°C has a composition with low heat resistance and low mechanical strength. On the other hand, if it exceeds 220"C, the sealing performance is poor.The melting point in the present invention is determined by the differential scanning pH meter (D
SC), thickness 9.1ms 20 hours after molding
A 10 mg sample was taken from the press sheet and heated at 10℃/
A heating curve was measured from 0 to 250°C at a heating rate of min, and the maximum endothermic peak was taken as the melting point (Tm).

・Copolymers with a softening point of less than 90°C have low heat resistance.

The softening point in the present invention is determined by using a thermal mechanical analyzer (TMA) to take a 1 cm square sample from a press sheet with a thickness of 1 Pengyuan 20 hours after molding.
Place a needle with a diameter of 0.025 inch on one side of the sample, apply a load of 49 g, heat it at a heating rate of 10°C/min, and read the temperature when the needle penetrates a depth of 0.11 mm to determine softening. It was marked as a point.

A copolymer with an X-ray crystallinity of less than 15% has an elastic modulus,
Mechanical strength is low; on the other hand, those exceeding 35% are too hard and have poor sealing properties. The crystallinity in the present invention is 20 after molding.
2x4c from a press sheet with a thickness of 1.01 after time elapsed
A sample of
After separating into crystalline parts and amorphous bone and measuring their areas, the crystalline parts were determined as weight %.

In addition, both press sheets were coated with random copolymers to a thickness of 0.1 and 1.5 mm, respectively. Pour the specified amount into the OB mold and 240
The mold was preheated for 5 minutes using a hydraulic press molding machine heated to 20°C, pressurized for 5 minutes, and then immediately transferred to a cooling press molding machine cooled with water at 20°C and cooled for 5 minutes.

Specifically, the α-olefin having 3 to 7 carbon atoms to be copolymerized with 4-methyl-1-pentene in the random copolymer (A) used in the present invention is propylene, 1-
Examples include butene, ■-pentene, ■-hexene, and ■-heptene. Among these α-olefins, 1-butene and 1-1-xeno are preferable, and 1-hexene is especially flexible. It is preferable because it has an excellent balance with rigidity.

Copolymers with ethylene are too soft and have poor heat resistance, while copolymers with 8 or more carbon atoms, such as 1-decene or 1-
Copolymers with hexadecene and the like also have poor heat resistance and low mechanical strength, and neither of them can achieve the object of the present invention.

In addition to the above properties, the random copolymer formula used in the present invention has a soluble content in acetone/n-decane mixed solvent (volume ratio 1/1) at 10°C of 4×[η]-oJ-σ, 2 weight% or less, and even 0.2X (η) to 3.8X (
23% by weight ([η] is the value of the intrinsic viscosity of the random copolymer [F], excluding the unit), which is the amount of low-molecular polymer components on the surface during molding. This is preferable because it does not cause stickiness due to bleed-out. In the present invention, the amount of the copolymer soluble in the M mixed solvent is measured and determined by the following method.

That is, in a 150 ml flask with a stirring blade, 1 g of copolymer sample and 0.05 g of 2,6-tert-
Add butyl-4-methylphenol, 50 mZ of n-decane, and dissolve on a 120'c oil solution. /8 After solving,
Allow to cool naturally at room temperature for 30 minutes, then add 50 ml of acetone in 30 seconds, and leave to cool on a 10°C water bath for 60 minutes.

The solution containing the precipitated copolymer and low molecular weight polymer component was filtered and separated using a glass filter, and the solution was collected in 1011 ml.
1g Te 150'CT: Kofl Ninal"i, Te Inui 5L
The weight was measured, and the soluble portion of the copolymer in the mixed solvent was calculated and determined as a percentage of the weight of the sample copolymer. In the measurement method described above, stirring was performed continuously from the time of melting to immediately before filtration.

To the 4-methyl-1-pentene/α-olefin random copolymer 8 having the above-mentioned properties, for example, (al) a magnesium compound, a titanium compound, a diester, and optionally a halogen compound (a magnesium compound or a titanium compound). (b) Organoaluminum compound catalyst component, and (cl
In the presence of a catalyst formed from an organosilicon compound catalyst component having Si-〇-C bonds, about 20 to about 200
4-methyl-1-pentene and 1-butene at a temperature of °C,■
- Obtained by copolymerizing with an α-olefin having 3 to 7 carbon atoms such as hexene.

The copolymerization conditions for producing the random copolymer φO suitable for use in the present invention as described above are detailed in Japanese Patent Application No. 60-216258 filed by the present applicant.

The packing material for the bottle of the present invention is composed of the above-mentioned random co-association as a main component, and has heat resistance,
In order to adjust the elastic modulus, flexibility, etc., the random copolymer (c) 100! (Up to 100 parts by weight, preferably 70 parts by weight, based on part f of polymethyl-1-pentene 03) may be added. The amount of poly(4-methyl-1-pentene) is 100. If it exceeds the tR portion, it becomes too hard and is therefore unsuitable as a packing material.

Such poly-4-methyl-1-pentene (B) is a homopolymer of 4-methyl-1 to pentene or 4-methyl-1-pentene.
1-Pentene and other α-olefins, such as ethylene,
Copolymer with α-olefin having 2 to 20 carbon atoms such as propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, etc., usually 4-methyl-1-pentene. Containing 85 mol% or more of 4
-It is a polymer mainly composed of methyl-1-pentene.

The melt flow rate (MFR, load: 5 kg, temperature: 260°C) of poly-4-methyl-1-pentene (B) is preferably in the range of 0.5 to 200 g/10 m1n. If the MFR is less than 0.5g/20m1n, the melt viscosity is high and the moldability is poor, and the MFR is less than 200g.
/10 m1n has a low melt viscosity and poor moldability, and also has low mechanical strength.

The random conformal polymer used in the present invention includes a heat stabilizer,
Nucleating agents, lubricants, pigments, dyes (I), fillers, foaming agents, foaming aids, etc. may also be added.

JI of the present invention! Packing materials such as Z can be used in an unfoamed state or as a foam. When using foam,
Foaming (& ratio is usually 3 times or less, preferably 1.3 to 2
This is twice the range. If the expansion ratio exceeds 3 times, the compressive strength and elastic recovery properties of the foam will be poor and it cannot be used as a packing material. The packing material according to the invention preferably has a thickness in the range of 0.5 to 5 nv, especially 1 to 41 nv.

As a method for producing a foam of the random copolymer (c), for example, azobisisobutyronitrile, abdicarboxylic acid amide, N, N'
- Contains a decomposable organic blowing agent such as dinitrosopentamethylene radramine, benzenesulfonyl hydrazide, p, p'-oxybis(benzenesulfonylhydrazide), toluenesulfonyl hydrazide, or a decomposable nonvolatile blowing agent such as sodium orthocarbonate. , a method of foaming by heating the compound to decompose the foaming agent, and a method of impregnating a random copolymer with an easily volatile organic solvent, plasticizing it under a high pressure state, and then transferring it to a low pressure state and foaming it. Alternatively, a method of blowing high-pressure gas such as air, nitrogen, carbon dioxide, etc. into the molten random copolymer (c) in a molding vessel can be mentioned.

In these cases, the method using a decomposable organic blowing agent is preferable because the expansion ratio of the foam can be easily adjusted, the cells tend to become closed cells, and a foam with good appearance and performance can be easily obtained. When blending such a degradable organic blowing agent, the blending history is usually 0. It is advisable to mix the amount of OI to 5% by weight, preferably about 0.1 to 2% by weight.

In order to manufacture the packing material for bottle caps and the like of the present invention, an unfoamed sheet or a foamed sheet is manufactured in advance by a known method such as calendar molding, extrusion molding, compression molding, injection molding, etc. A method of forming a packing material into a predetermined shape from a sheet or foam sheet, and if necessary, fitting it to the metal outer shell of the crown or cap or pasting it with adhesive or other means, or After supplying a predetermined amount of the random copolymer (A) in a molten state or a solidified state, the resin is heated and foamed as necessary and cooled, or heated and molded using a suitably heated plunger to form a predetermined shape. Methods such as doing this can be adopted.

Bottle lids and the like to which the packing material of the present invention can be used include, for example, crowns such as long skirt crowns and short skirt crowns, screw caps, high neck caps, roll-on caps, pilfer-proof caps, twist-off caps, and side seals. Caps, flute caps, securo caps, flavor lock caps, royal caps, omnia caps, turn-off crowns, etc. can be mentioned.

〔Effect of the invention〕

The packing material for bottle caps, etc. made of the 4-methyl-1-pentene/α-olefin random copolymer of the present invention is ■(
It is heat resistant enough to withstand heat, especially boiling in boiling water and high-pressure steam sterilization at 120°C, and has excellent food hygiene, and is not altered by acids, alcohol, salt solutions, etc. Moreover, it does not have any reactivity with the liquid content, colorants, fragrances, etc., and does not alter the flavor or change the taste.

In addition, it has an excellent balance between flexibility and elastic modulus, so
Good airtightness can be obtained with low plugging pressure, and the airtightness is also excellent in durability. Taking advantage of these characteristics, it is suitably used as a packing material for applications where baby food, dairy products, pharmaceuticals, sterilized water, etc. are filled into bottles and then subjected to high-temperature treatment such as boiling or high-pressure steam sterilization.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way unless the gist of the invention is exceeded.

Example 1 [Production of 4-methyl-1-pentene/1-hexene random copolymer] Preparation of titanium catalyst component (a)> Anhydrous magnesium chloride 4.76 g (50 mmol)
, Deccan 25ml Oc! l: 23.4mZ (150mmol) of 2-ethylhexyl alcohol
After performing a heating reaction at 30°C for 2 hours to obtain a homogeneous/g liquid,
In this solution, 1.11 g of anhydrous phthalic acid (7.5 mmo
1) and stirred and mixed for an additional hour at 130'C to dissolve phthalic anhydride into the homogeneous solution. After cooling the homogeneous solution obtained in this way to room temperature, 200 mZ of titanium tetrachloride (1.8 mmol) kept at -20°C
) over a period of 1 hour. After charging, the temperature of this mixed solution was raised to 110"C over 4 hours, and when it reached 110°C, di-isobutyl phthalate 2.6811 (12.5 mmol I) was added and heated for 2 hours. Keep the stirring ball at the same temperature.After the reaction for 2 hours, collect the solid part by hot filtration.
After resuspending in 0mf of 7'1Cf4,
Heat the reaction at ℃ for 2 hours. After the reaction is completed, the solid portion is again collected by hot filtration and thoroughly washed with decane and hexane at 110° C. until no free titanium compound is detected in the washing liquid. The titanium catalyst component (al) prepared by the above production method was stored as a hexane slurry, and a portion of it was dried for the purpose of investigating the catalyst composition.

The titanium catalyst component thus obtained (11) had the following composition: titanium 3.1m%, chlorine 56.0m%, magnesium 17.0m9%, and diisobutyl phthalate 20m%.
．． It was 9%.

Polymerization> 200 ff (7) Susg to reaction vessel, 2 per hour
010) ■-hexene, 601 4-methyl-1-pentene (hereinafter abbreviated as 4MP), 80 mmol triethylaluminum, 80 mmol 1 trimethylmethoxysilane, 2 mmol titanium catalyst component (al was charged continuously.The hydrogen partial pressure in the gas phase was kept at 1.5 kg/cnl, and the polymerization temperature was kept at 70°C.
I kept it.

Continuously draw out m mixed solution so that the liquid volume in the reaction vessel becomes 1001 g, stop the polymerization with a small amount of methanol, remove unreacted monomer, and produce 7.5 g of copolymer per hour. I got it. The thus obtained 4-methyl-1-pentene/1-hexene random copolymer (hereinafter abbreviated as PMH-I) has a 4MP content of 55 mol% and a melting point of 168°.
The C1 softening point was 140° C1 crystallinity was 24%, the intrinsic viscosity [η] was 2.2 ip/g, and the acetone/n-decane soluble content was 1.7ii%.

[Manufacture of bottle lids]

The PMI-1-1 was processed using a 50 mmφ extruder (molding temperature 20
After melting at 0''C), it was fed to a T-die (forming temperature: 200°C) to produce a sheet with a thickness of 2mm.

A disk with a diameter of 27 mm was punched out from this sheet and fitted into the outer shell of the crown, and then the crown was corked at a capping pressure of 300 kg into a 210 cc bottle filled to the neck with hot water at 95°C.

Next, the bottle was left in a constant temperature room at 23°C for 24 hours, and the pressure inside the bottle was measured using a vacuum tester. The results are shown in Table 1.

Note that the numerical values in the table represent the number of bottles that showed an abnormal value (degree of vacuum 200 mm, 11 g or less) out of 100 bottles subjected to the test.

After capping the crown and leaving it in a constant temperature bath at 80°C for 30 minutes,
Furthermore, the pressure inside the bottle was similarly measured for bottles that were left in a constant temperature room at 23°C for 24 hours, and those that were left in a constant temperature room at 110°C for 30 minutes and then left in a constant temperature room at 23°C for another 24 hours. did.

Heat resistance: The sheet was placed in a hot air circulation oven at 120° C., and the appearance was observed after 1 hour to evaluate the presence or absence of deformation and dimensional changes.

○ Hardly any deformation or shrinkage is observed.

△ Some deformation and shrinkage are observed.

× Significant deformation and shrinkage are observed.

Hardness: According to JIS K 6301, JISA
Spring hardness was measured.

Expansion ratio: Performed according to ASTM D792.

Example 2 Example 1 (7) was used instead of PMH-1 used in Example 1.
PMHI 1% 4) 1-pentene [1-hexadecene/l-octadecene (weight ratio 1/
1) Content ■6 mol%: MFR: 26 g/lo
min, hereinafter abbreviated as PMP-1] was mixed in a Henschel mixer at a molding temperature of 24%.
A T-die sheet was molded in the same manner as in Example 1 except that the temperature was 0°C, and a total of 1i [[i] was formed. The results are shown in Table 1.

Example 3 In place of PMH-I used in Example 1, iM was obtained by polymerizing by changing the charging amounts of 1-hexene and 4MP and changing the hydrogen partial pressure appropriately. 4- with a P content of 70 mol%, a melting point of 195°C, a softening point of 165°C, a crystallinity of 26%, an intrinsic viscosity [η) of 2.5 dl/g, and an acetone/n-decane soluble content of 2.0fffffi%.
The same procedure as in Example 1 was carried out except that methyl-1-pentene/1-hexene random copolymer (hereinafter abbreviated as PMII-n) was used. The results are shown in Table 1.

Example 4 After mixing 100 parts by weight of PMI-1-I used in Example 1 and 0.5 parts by weight of azodicarboxylic acid amide using a Henschel mixer, the same procedure as in Example 1 was carried out to obtain a foamed sheet. The following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 5 In Example 2, 1 part of azodicarboxylic acid amide o, 5% y-1 part was mixed with a Henschel mixer to 100 parts of a mixture of 70% by weight of PMH-I and 130% by weight of PMP-130, using a Henschel mixer. The same procedure as in Example 2 was carried out to obtain a foamed sheet. The following procedure was carried out in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 1 PMP-1 was used instead of PMII-■ used in Example 1.
The same procedure as in Example 1 was conducted except that the molding temperature was 230° C. The results are shown in Table 1.

Comparative Example 2 The same procedure as in Example 4 was carried out except that PMP-1 was used instead of PMTI-1 used in Example 4 and the molding temperature was 230'c. The results are shown in Table 1.

Comparative Example 3 In place of P and MH-1 used in Example 1, high-pressure low density polyethylene (Mirason 4 manufactured by DuPont Mitsui Polychemicals Co., Ltd.
1. VFR (ASTM D1238.E) 0
．． 9g/10mln, density 0.918g/a+l
) (hereinafter abbreviated as LDPE) at a molding temperature of 1.
The same procedure as in Example 1 was conducted except that the temperature was 60°C. The results are shown in Table 1.

Comparative Example 4 To 100 parts by weight of LDPE used in Comparative Example 3, 1.0% of azodicarphonamide was added. The same procedure as in Comparative Example 3 was carried out after mixing with a certain amount of OM using a Henschel mixer.

The results are shown in Table 1.

Claims (1)

[Claims] (1) 4-methyl-1-pentene content is 40 to 8
0 mol%, melting point 140 to 220°C, softening point 90
Crystallinity at 190°C to 190°C and X-rays is 15 to 3
It is characterized by consisting of a random copolymer (A) of 4-methyl-1-pentene in the range of 5% and an α-olefin having 3 to 7 carbon atoms (excluding 4-methyl-1-pentene). Packing materials for bottle caps, etc.