JPH1052897A - Easily releasable film and easily releasable sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widen a heat sealing temperature range and to improve low- temperature salability, heat resistant and impact resistance by specifying content and density of α-olefin of ethylene-α-olefin copolymer, and setting a melt flow rate to a specific range. SOLUTION: Ethylene-α-olefin copolymer contains 7 to 20wt.% α-olefin content and has 0.892 to 0.925g/cm<3> density to improve its heat sealing strength and sealability of contents. The ethylene-α-olefin copolymer has a range of a melt flow rate of 0.1 to 40g/10min in terms of a load of 2.16kg at 190 deg.C to obtain stable molten film with film processability. The method for manufacturing it comprises the steps of executing in gas-solid, gas-liquid, liquid-solid or uniform liquid phase in the presence of Ziegler catalyst by using ethylene and α-olefin. The polymerization is conducted by a method such as a batch type or semi- continuous type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for easy peeling and a seal material for easy peeling using the film for easy peeling.

[0002]

2. Description of the Related Art Polypropylene has excellent characteristics such as excellent heat resistance, moldability, mechanical properties and appearance, easy handling when treated as waste, and little influence on foods. Taking advantage of these properties, polypropylene is widely used as a packaging material for various foods or as a simple tableware that also serves as a packaging material. As the lids of these containers, those of an easy-open type that can be opened with a suitable force without resistance are widely used, and accordingly, development of an easily peelable lid material optimal for polypropylene is desired.

[0003] Conventionally, a special resin such as an ionomer or a modified ethylene-vinyl acetate copolymer is used directly or as a blend in a seal layer to exhibit a property of being easily peelable from polypropylene, ie, exhibiting easy peelability. Alternatively, an adhesive such as a low molecular weight ethylene-vinyl acetate copolymer (EVA) is applied to a base film to develop an appropriate adhesive strength. However, when an adhesive is used, problems such as deterioration of the working environment due to the use of an organic solvent in a coating process and leakage of contents due to a decrease in mechanical strength at low temperatures have been raised. In addition, these lid materials are easily affected by heat and moisture due to the properties of the sealing layer, are inferior in heat resistance, and their use range is somewhat restricted. In addition, ethylene-vinyl acetate copolymers and ionomers tend to generate odor, and are not suitable for food applications.

Further, a technique using a polypropylene-based material as a sealant is known. For example, JP-A-61-246061 discloses that a resin composition comprising 40 to 80% by weight of polypropylene and 60 to 20% by weight of a low-crystalline ethylene-α-olefin copolymer is used as a heat seal portion. It has been disclosed. Japanese Patent Application Laid-Open No. 6-328639 discloses polybutene,
It is disclosed that a resin composition containing polyethylene and polypropylene is used as a heat seal portion, and polypropylene is used as a base material layer. However, both resin compositions have problems such as inadequate low-temperature sealing properties because polypropylene is an essential component, and a narrow appropriate heat-sealing temperature range.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an easy-peeling film which has an appropriate easy-to-peel property and a necessary and sufficient heat resistance, impact resistance and low-temperature heat sealability when used as a packaging material. An object of the present invention is to provide an easily peelable sealing material comprising the film and a base material.

[0006]

Means for Solving the Problems The present inventors have developed an easy-peeling film having easy-peeling properties, heat resistance, impact resistance and low-temperature heat-sealing properties, and an easy-peeling sealing material comprising the film and a base material. As a result of the study, it was surprisingly found that the object of the present invention was achieved when only a specific ethylene-α-olefin copolymer was used as a sealing material film without using polypropylene, and the present invention was completed.

That is, according to the present invention, the content of α-olefin is 7 to 20% by weight and the density is 0.892 to 0.925 g.
/ Cm ³ , 190 ° C., melt flow rate (MFR) measured under conditions of 2.16 kg load is 0.1 to 40 g /
A film for easy peeling, comprising an ethylene-α-olefin copolymer in a range of 10 minutes.
Further, the present invention is an easy-peeling seal material comprising the above-mentioned easy-peeling film and a base material.
Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The term "easy peeling" in the present invention means that practical sealing properties are ensured and that opening by human hands is easy. More specifically, the heat-sealed seal material for easy peeling and the container made of a polypropylene resin were heated at 180 ° and 90 ° at a peeling speed of 300 mm / min.
As a result of the peel test, the peel strength was 600
~ 2500g / 15mm width and 400-2000g /
Those having an appropriate sealing temperature range having a width of 30 ° C. or more within a range of 15 mm width are referred to as those having easy peelability. If the 180 ° peel strength is less than 600 g / 15 mm width or the 90 ° peel strength is less than 400 g / 15 mm width, the sealing performance of the contents may be reduced, and the seal may be peeled off due to impact during transportation. On the other hand, 180
° Peel strength exceeds 2500 g / 15 mm width or 90
If the peel strength exceeds 2,000 g / 15 mm width, the film does not show easy peelability and may be difficult to peel by hand.

The ethylene-α-olefin copolymer according to the present invention has an α-olefin content of 7 to 20% by weight, preferably 8 to 18% by weight, and a density of 0.892 to 0.92.
5 g / cm ³ , preferably 0.895 to 0.920 g /
cm ³ , more preferably 0.895 to 0.912 g /
cm ³ . The density was measured according to JIS-K6760. If the content of α-olefin is less than 7% by weight or the density exceeds 0.925 g / cm ³ , the heat seal strength with polypropylene cannot be sufficiently obtained,
Poor sealability of contents. The content of α-olefin is more than 20% by weight or the density is 0.892 g / c
If it is less than m ³ , the film becomes more flexible than necessary and handling becomes difficult. As the α-olefin of the copolymer, for example, propylene, butene-1, hexene-
1, α-olefins having 3 to 12 carbon atoms, such as octene-1. Further, the present invention provides an ethylene-α-olefin copolymer having a density of 0.895 to 0.920 g / cm
^And the α-olefin is α-olefin having 3 to 12 carbon atoms.
A film for easy release made of an ethylene-α-olefin copolymer which is an olefin is preferred.

The ethylene-α-olefin copolymer according to the present invention has a melt flow rate (MFR) at 190 ° C. under a load of 2.16 kg of 0.1 to 40 g / 10 minutes,
Preferably it is in the range of 0.1 to 25 g / 10 minutes. The ethylene-α-olefin copolymer has an MFR of 0.1 g.
A film having a length of less than / 10 minutes is inferior in film processability and is not preferred. When the MFR exceeds 40 g / 10 min, a stable molten film cannot be obtained, and it is difficult to form a film. Further, when used as a lid material, the seal layer is significantly deformed, and the heat seal strength and appearance are impaired. Therefore, it is not preferable.

When the ethylene-α-olefin copolymer of the present invention is formed into a sheet having a thickness of 0.3 mm,
It is preferable to use an ethylene-α-olefin copolymer in which the bleeding on the sheet surface after lapse of days (excluding the bleeding of the additive) is 0.25 mg / cm ² or less.

The process for producing an ethylene-α-olefin copolymer according to the present invention is carried out by using ethylene and an α-olefin in the presence of a Ziegler catalyst or a metallocene catalyst, usually at 0 to 300 ° C. and normal pressure 3000 kg / cm ² ,
In the presence or absence of a solvent, gas-solid, gas-liquid, liquid-
It is carried out under a solid or homogeneous liquid phase. Further, the polymerization can be carried out by any of batch, semi-continuous, and continuous methods. Further, the polymerization can be performed in two or more stages having different reaction conditions. In addition, adjustment of molecular weight
Although it can be adjusted by the polymerization temperature, the catalyst concentration, the amount of the comonomer, and the like, it is efficiently performed by adding hydrogen to the polymerization system.

The Ziegler catalyst is formed from a solid catalyst component containing a transition metal, a cocatalyst component comprising an organoaluminum compound, and, if necessary, a carrier.

The metallocene catalyst is at least one compound selected from the group consisting of organoaluminum oxy compounds, organoaluminum compounds, and compounds that react with a reaction product of a transition metal compound and an organometallic compound to form a stable anion.
Group III transition metal compounds, optionally formed from a support.

The ethylene-α-olefin copolymer according to the present invention may be used alone, but if the conditions of the final composition are within the scope of the present invention, the ethylene-α-olefin copolymer may be used as an ethylene-α-olefin copolymer. One or more α-olefin copolymers and / or ethylene homopolymers may be used as a mixture. For example, after mixing the above mixture with a Henschel mixer, a tumbler blender, etc., a film may be directly formed, or the above mixture may be extruded, a kneader,
A film may be formed by using a material kneaded after kneading with a Banbury mixer or the like.

The method for forming the film for easy peeling of the present invention is not particularly limited, and an inflation film forming apparatus, a T-die film forming apparatus, or the like can be generally used.

Further, the ethylene-α-olefin copolymer according to the present invention may be, if necessary, a metal soap such as calcium stearate; a neutralizing agent such as hydrotalcite;
2,6-di-t-butyl-p-cresol (BHT),
Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (I
RGANOX1010), a phenolic heat stabilizer represented by n-octadecyl-3- (4'-hydroxy-3,5'-di-t-butylphenyl) propionate (IRGANOX1076); bis (2,4-di-t -Butylphenyl) pentaerythritol diphosphite and phosphite-based heat stabilizers represented by tris (2,4-di-t-butylphenyl) phosphite; lubricants represented by higher fatty acid amides and higher fatty acid esters; An antistatic agent such as an aliphatic glycerin ester having 8 to 22 carbon atoms, a sorbitan acid ester or a polyethylene glycol ester; an antiblocking agent represented by silica, calcium carbonate, talc and the like; a weathering stabilizer, an antifogging agent, a pigment, Various compounds commonly used in addition to polyolefin resins such as dyes, dropping agents, nucleating agents, etc. You may include in the range which does not impair.

The ethylene-α-olefin copolymer according to the present invention may be incorporated, if necessary, within a range where high-pressure polyethylene is usually used as a processability modifier and within a range that does not impair the object of the present invention. You may.

The seal material for easy peeling of the present invention comprises a film for easy peeling comprising the above-mentioned ethylene-α-olefin copolymer and a substrate. The film for easy peeling may use the ethylene-α-olefin copolymer according to the present invention in a single layer, and further use the ethylene-α-olefin copolymer as a multilayer film having at least one surface layer. You may. The method for forming the multilayer film is not particularly limited, and examples thereof include a coextrusion molding method and a sandwich molding method. Examples of the material of the multilayer film include a polyethylene resin having a higher density than the above-mentioned ethylene-α-olefin copolymer.

The method for producing the easily peelable seal material of the present invention is not particularly limited, and examples thereof include various known methods such as a dry lamination method, an extrusion lamination method, a sand lamination method, and a coextrusion method.

As the substrate according to the present invention, for example, any polymer capable of forming a film, paper, aluminum foil, cellophane and the like can be used. Examples of the polymer capable of forming a film include polyamide resins such as nylon 6, nylon 66, nylon 11, and nylon 12; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polypropylene and poly-1-.
Polyolefin resins such as butene and poly-4-methyl-1-pentene; polyvinylidene chloride, polyvinyl chloride, polystyrene, polyvinyl alcohol, ethylene
Examples thereof include vinyl alcohol copolymers and polycarbonates, which can be appropriately selected in consideration of gas barrier properties, printability, transparency, rigidity, adhesiveness, and the like. Further, the base material may be used by laminating a plurality of materials as necessary. When the substrate is stretchable, it may be stretched uniaxially or biaxially. Among these, the substrate is preferably a polyamide resin, a polyester resin, an aluminum foil or the like.

The polypropylene resin to be adhered to the film for easy peeling and the sealing material for easy peeling of the present invention is not particularly limited. For example, propylene homopolymer, propylene-ethylene random copolymer and propylene
Ethylene block copolymers are exemplified. The content of these ethylenes is not particularly limited.
１５15% by weight.

[0023]

As described above in detail, according to the present invention, an easy-peeling film having excellent low-temperature sealing properties, a wide heat-sealing temperature range, heat resistance and impact resistance, and a film and a substrate. And a seal material for easy peeling comprising: Further, the present invention is most suitable as a film for easy peeling such as a container made of a polypropylene resin and a sealing material for easy peeling.

[0024]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples.

First, methods for measuring physical properties in the following examples and comparative examples will be described. (1) Density (d) According to the method specified in JIS K6760. 100
After annealing for 1 hour in water at ℃, the density was measured. However, the sample having a density of less than 0.905 g / cm ³ was not annealed. (2) Melt flow rate (MFR) According to condition 4 of Table 1 of JIS K6760, at 190 ° C.
The measurement was performed under the condition of 2.16 kg load. (3) Surface bleed amount 150 mm x 150 m using a 150 ° C hot press
A required number of sheets of mx 0.3 mm were prepared and adjusted by aging for 7 days in a 60 ° C oven without contacting each other. The sheet was washed with 300 ml of heptane per sheet, and the liquid was recovered, dried and weighed. The value obtained by dividing the measured weight by the sheet surface area was defined as the surface bleed amount. In the measurement of the amount of surface bleed, the sample used had no additive formulation as much as possible. When it was difficult to prepare an additive-free sample, the high-performance liquid chromatography and gas chromatography of the washed and recovered surface bleed component were measured, and the concentrations of various additives were calculated from the results and corrected.

(4) α-Olefin content Determined by the characteristic absorption of α-olefin using an infrared spectrophotometer. (5) Seal strength The easy-peeling film side of the easy-peeling seal material composed of the base material and the easy-peeling film is superimposed on the sheet made of the polypropylene resin as the adherend,
At a sealing temperature of 0 ° C. and 220 ° C., under a pressure of 4 kg / cm ² , the resultant was heat-sealed with a 10 mm seal bar, and then sufficiently cooled. A test piece having a width of 15 mm was collected from the obtained sample, and the crosshead speed was 300 mm / min and the peel angle was 1
The strength when the seal portion was peeled at 80 ° and 90 ° was defined as the seal strength (g / 15 mm). In Examples and Comparative Examples, peeling occurred between the sheet made of the polypropylene resin as the adherend and the film for easy peeling without peeling between the substrate layer and the film for easy peeling. (6) Tensile impact strength Measured based on ASTM D1822-61T.

Example 1 An ethylene-1-hexene copolymer having a density of 0.912 g / cm ³ and an MFR of 2 g / 10 min was formed into a film by an inflation method at a processing temperature of 170 ° C., and was applied to a stretched polyamide film by dry lamination. I combined. This was heat-sealed under the conditions described above with a 500 μm press sheet made of a propylene-ethylene random copolymer (MFR (measured at 230 ° C.) 7.5 g / 10 min, ethylene content 4.5% by weight) as an adherend. The seal strength was measured under the same conditions as described above. Table 1 shows the results.

Example 2 Example 1 was repeated except that the ethylene-1-butene copolymer of Example 1 was replaced with an ethylene-1-butene copolymer having a density of 0.905 g / cm ³ and an MFR of 2 g / 10 min. 1
Same as. Table 1 shows the measurement results.

Example 3 Example 1 was repeated except that the ethylene-1-hexene copolymer used in Example 1 was replaced with an ethylene-1-hexene copolymer having a density of 0.908 g / cm ³ and an MFR of 2 g / 10 min. Same as 1. Table 1 shows the measurement results.

Example 4 The procedure of Example 1 was repeated except that the ethylene-1-hexene copolymer of Example 1 was replaced with an ethylene-1-hexene copolymer having a density of 0.921 g / cm ³ and an MFR of 2 g / 10 min. Same as 1. Table 1 shows the measurement results.

Comparative Example 1 The procedure of Example 1 was repeated except that the ethylene-1-hexene copolymer of Example 1 was replaced with an ethylene-1-hexene copolymer having a density of 0.932 g / cm ³ and an MFR of 2 g / 10 min. Same as 1. Table 1 shows the measurement results.

Example 5 Instead of the ethylene-1-hexene copolymer of Example 1, an ethylene-1-hexene copolymer having a density of 0.908 g / cm ³ and an MFR of 2 g / 10 min was used as an adherend. M
Example 1 was repeated except that a propylene homopolymer having an FR (measured at 230 ° C.) of 8.5 g / 10 min was used. Table 2 shows the measurement results.

Example 6 The procedure of Example 5 was repeated except that the ethylene-1-butene copolymer of Example 5 was replaced with an ethylene-1-butene copolymer having a density of 0.905 g / cm ³ and an MFR of 2 g / 10 min. 5
Same as. Table 2 shows the measurement results.

Comparative Example 2 The procedure of Example 5 was repeated except that the ethylene-1-hexene copolymer of Example 5 was replaced with an ethylene-1-hexene copolymer having a density of 0.932 g / cm ³ and an MFR of 2 g / 10 min. Same as 5. Table 2 shows the measurement results.

Example 7 Instead of the ethylene-1-hexene copolymer of Example 1, an ethylene-1-butene copolymer having a density of 0.905 g / cm ³ and an MFR of 2 g / 10 min was used as an adherend. Propylene-ethylene block copolymer (MFR (230 ° C
(Measurement) was 9 g / 10 min, and the ethylene content was 2% by weight). Table 3 shows the measurement results.

Example 8 Instead of the ethylene-1-butene copolymer of Example 7,
Density 0.908g / cm ^Three, MFR2g / 10min Echile
Example 7 except that a 1-hexene copolymer was used.
I did the same. Table 3 shows the measurement results.

Comparative Example 3 Instead of the ethylene-1-butene copolymer of Example 7,
Density 0.932g / cm ^Three, MFR2g / 10min Echile
Example 7 except that a 1-hexene copolymer was used.
I did the same. Table 3 shows the measurement results.

Example 9 In place of the ethylene-1-hexene copolymer of Example 1, an ethylene-1-butene copolymer having a density of 0.900 g / cm ³ and an MFR of 2 g / 10 min was used as an adherend. MF
R (measured at 230 ° C.) was 60 g / 10 minutes, and the procedure was the same as that of Example 1 except that a propylene homopolymer containing 2.5% by weight of titanium dioxide was used. Table 4 shows the measurement results.

Example 10 Instead of the ethylene-1-butene copolymer of Example 9,
Density 0.895g / cm ^Three, MFR2g / 10min Echile
Example 9 except that a 1-butene copolymer was used.
I did it. Table 4 shows the measurement results.

Comparative Example 4 Instead of the ethylene-1-butene copolymer of Example 9,
Density 0.890g / cm ^Three, MFR1g / 10min
Example 9 except that a 1-butene copolymer was used.
I did it. Table 4 shows the measurement results. Excessive surface bleed
No peel strength after heat sealing due to excess
Was.

[0041]

[Table 1] {Example Example Comparative Example 1 2 3 4 1} ────────────────────────────── Substrate Propylene-ethylene random copolymer α-olefin C'6 C'4 C '6 C'6 C'6 content wt% 13.0 11.2 13.3 10.8 5.4 Surface bleed mg / cm ² 0 0 0.02 0 0 MFR g / 10 min 2 2 2 2 2 Density g / cm ³ 0.912 0.905 0.908 0.921 0.932 Tensile impact Strength kg ・ cm / cm ² 1500 1300 1770 1360 650 ───────────────────────────────── Seal strength g / 15mm 180 ° peel 160 ° C 880 1730 1580 950 820 190 ° C 1070 2280 2150 1020 900 220 ° C 990 2050 2130 1030 820 90 ° peel 160 ° C 410 2280 1570 340 310 190 ° C 440 2100 1830 440 300 220 ° C 540 1830 1760 470 310 ── ────────────────────────── ────

[0042]

[Table 2]

[0043]

[Table 3] Example Comparative Example 7 8 3}被 Substrate Propylene-ethylene block copolymer α-olefin C'4 C'6 C'6 content wt% 11.2 13.3 5.4 Surface bleed mg / cm ² 0 0.02 0 MFR g / 10 min 2 2 2 Density g / cm ³ 0.905 0.908 0.932 Tensile impact strength kg · cm / cm ² 1300 1770 650 ─────────────────シ ー ル Seal strength g / 15mm 180 ° peeling 160 ° C 1730 1730 550 190 ° C 1760 1990 1010 220 ° C 1900 1870 910 90 ° peeling 160 ° C 1570 630 170 190 190 ° C 1490 960 390 220 ° C 1750 1150 380 ────────────────────────────

[0044]

[Table 4]

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C08J 5/18 CES C08J 5/18 CES (72) Inventor Yasuaki Suzuki 5 Anesaki Beach, Ichihara City, Chiba Prefecture (1) Sumitomo Chemical Co., Ltd. (72) Inventor Satoru Hosoda 2-27-1, Shinkawa, Chuo-ku, Tokyo Sumitomo Chemical Industries, Ltd. (72) Inventor Masami Yoshimoto 3-chome, Kutaro-cho, Chuo-ku, Osaka-shi No. 6-8 Toyo Aluminum Co., Ltd. (72) Toshihiko Nakano 3-8, Kutaro-cho, Chuo-ku, Osaka-shi No. 6-8 Inside Toyo Aluminum Co., Ltd. (72) Mamoru Kamata, 3-chome, Kutaro-cho, Chuo-ku, Osaka-shi No. 6-8 Inside Toyo Aluminum Co., Ltd.

Claims (5)

[Claims] (1) an α-olefin content of 7 to 20% by weight;
The density is 0.892 to 0.925 g / cm ³ , 190 ° C.,
2. The melt flow rate (MFR) measured under the condition of a load of 16 kg is in the range of 0.1 to 40 g / 10 min.
An easily peelable film comprising an ethylene-α-olefin copolymer. 2. An ethylene-α-olefin copolymer having a high density
0.895-0.920 g / cm ^ThreeAnd α-
The olefin is an α-olefin having 3 to 12 carbon atoms.
The film for easy release according to claim 1. 3. An ethylene-α-olefin copolymer containing 0.1% by weight of
The bleeding material (excluding bleeding material of the additive) on the sheet surface after aging at 60 ° C. for 7 days when the sheet has a thickness of 3 mm is 0.25 mg / cm ² or less.
The film for easy release according to the above. 4. A film for easy peeling comprising a multilayer film comprising the ethylene-α-olefin copolymer according to claim 1 as at least one surface layer. 5. A seal material for easy peeling comprising the film for easy peel according to claim 1 and a substrate.