JPH1112558A - Resin composition for sealant of retort film and sealant film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in impact resistance at a low temperature, also transparency at a high temperature, resistance to melt adhesion by heating, sealing strength characteristic, etc., by blending a specific high density polyethylene with a specific linear low density polyethylene. SOLUTION: This resin composition for a sealant of a retort film is obtained by blending (A) 55-95 pt.wt. high density polyethylene having 0.945-0.970 g/cm<3> density and 0.5-10 g/10 min melt flow rate (ASTM D 1238, at 190 deg.C, load 2.16 kg) with (B) 5-45 pt.wt. (A+B makes 100 pts.wt.) linear low density polyethylene having 0.890-0.925 g/cm<3> density and 0.5-10 g/10 min melt flow rate (ASTM D 1238, at 190 deg.C, load 2.16 kg) and produced by using a metallocene catalyst. As the component (B), an ethylene/α-olefin copolymer consisting of 95-99 mol.% ethylene component and 15 mol.% 3-12C α-olefin component, is preferably used, and that having 1.5-3.5 ratio of weight averaged molecular weight (Mw) to number averaged molecular weight (Mn) is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for a sealant of a retort film (or a retort pouch) and a sealant film for a retort film (or a retort pouch) comprising the composition.

[0002]

BACKGROUND OF THE INVENTION In recent years, the demand for retort foods has increased rapidly due to the development of the food service industry, and moreover, retort pouches have been increased in size, and the amount and number of contents to be put in pouches (bags) have been increasing. .

Hitherto, polypropylene having a high melting point has been mainly used from the viewpoint of heat resistance as a sealant material (the innermost surface material of the retort pouch) of the retort film forming the retort pouch. As a result, the weight of the entire contents has increased, and accordingly, there has been a demand for increasing the bag breaking strength during low-temperature storage.

[0004] The use of a polyethylene resin instead of polypropylene improves the bag breaking strength at low temperatures (low-temperature impact resistance). However, when the resin is heat-sterilized (boiling, retorting) at 100 to 125 ° C. , Heat fusion,
Problems such as thermal deformation, whitening (decrease in transparency), and breakage of a seal occur. Japanese Patent Application Laid-Open No. 8-3383 discloses ethylene / α.
-It is stated that by blending a small amount of high-density polyethylene with an olefin copolymer, a sealant film having excellent extrudability, heat resistance and low-temperature impact resistance can be obtained. However, since the sealant film contains a lot of low-density components, it does not show appropriate whitening resistance, deformation resistance and heat melting property when boiled at a high temperature.

Now, the present inventors have developed a high density polyethylene (HDPE) having a specific density and melt flow rate.
And a composition prepared using a metallocene-based catalyst and containing a linear low-density polyethylene (LLDPE) having a specific density and a melt flow rate in a specific ratio as a sealant material for a retort film, They have found that physical properties at low and high temperatures can be improved, and have completed the present invention.

[0006]

An object of the present invention is to provide a resin composition capable of forming a sealant film for a retort film having excellent low-temperature impact resistance and excellent high-temperature transparency, heat-fusible properties, heat-resistant deformation properties and seal strength properties. And a sealant film thereof.

[0007]

SUMMARY OF THE INVENTION The resin composition for a sealant of a retort film according to the present invention has (A) a density of 0.945 to 0.9.
70 g / cm ³ and a melt flow rate (ASTM D 1
238, 190 ° C, load 2.16 kg) 55 to 95 parts by weight of high-density polyethylene having a weight of 0.5 to 10 g / 10 minutes;
It is prepared using a metallocene catalyst and has a density of 0.1.
890-0.925 g / cm ³ and a melt flow rate (ASTM D 1238, 190 ° C., load 2.16 kg) of 0.5-1.
0-g / 10 min linear low density polyethylene 5-45
Characterized by the fact that it contains 100 parts by weight [total amount of components (A) and (B) is 100 parts by weight].

In the present invention, among such resin compositions, the film impact strength at -5.degree.
200 kg · cm / cm or more and 180 ° C at 120 ° C
The haze of the film after boiled for 0 second is 5.5%
A film having a tensile strength at break at -20 ° C (seal strength) of 20 N / 15 mm or more and a tensile elongation at break at -20 ° C (seal elongation) of 200% or more is formed. Preferred are resin compositions that can be used.

Further, the sealant film for a retort film according to the present invention is characterized in that it is a film formed from the resin composition for a sealant for a retort film according to the present invention.

In the present invention, among such films, the film impact strength at -5 ° C. is 12
00 kg · cm / cm or more and 1800 at 120 ° C
The haze of the film after the boil treatment for 5.5 seconds is 5.5% or less, and the tensile strength at break at 20 ° C. (seal strength) of the heat-sealed portion is 20 N / 15 mm or more;
Tensile elongation at break at -20 ° C (seal elongation) is 20
A film having 0% or more is preferable.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the resin composition for a retort film according to the present invention and the sealant film for a retort film comprising the resin composition will be described in detail.

The resin composition for a sealant of a retort film according to the present invention contains a high-density polyethylene (A) and a linear low-density polyethylene (B). High density polyethylene (A) The high density polyethylene (A) used in the present invention has a high density
(Measured in accordance with ASTM D-1505) is 0.945 to 0.97
0 g / cm ³ , preferably 0.945 to 0.965 g /
cm ³ , more preferably 0.950 to 0.960 g /
cm ³ . When a high-density polyethylene (A) having a density within the above range is used, the deformation starting temperature (Td) is high,
In addition, a composition that can form a film with almost no loss of transparency is obtained. When such a composition containing high-density polyethylene (A) is used, the temperature of the heat sterilization treatment can be increased, and the time of the heat sterilization treatment can be shortened.

Further, this high-density polyethylene (A)
Melt flow rate (MFR; ASTM D 1238 (190 ° C, load
2.16 kg) according to 0.5 to 10 g / 10 min.
Preferably it is 0.5 to 8 g / 10 min, more preferably 1.0 to 6.0 g / 10 min. When the melt flow rate of the high-density polyethylene is within the above range, the resulting high-density polyethylene composition has good film moldability,
In particular, the extrudability of the resin in the air-cooled inflation molding method is favorable, and the use of such a composition containing high-density polyethylene (A) is preferable because a film having a balanced strength in each of the vertical and horizontal directions is obtained. .

The high-density polyethylene (A) used in the present invention may be a high-density polyethylene having the above-mentioned density and melt flow rate. Not only ethylene homopolymer but also ethylene and a small amount of α-olefin Propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-
An ethylene / α-olefin copolymer obtained by copolymerizing an α-olefin such as pentene and 4-methyl-1-pentene can also be used.

The composition of such an ethylene / α-olefin copolymer is usually about 200 m in a 10 mmφ sample tube.
¹³ C-N of g of ethylene · alpha-olefin copolymer was homogeneously dissolved in hexachlorobutadiene 1ml sample
The MR spectrum was measured at a measurement temperature of 120 ° C. and a measurement frequency of 2.
It is determined by measuring under the conditions of 5.05 MHz, a spectral width of 1500 Hz, a pulse repetition time of 4.2 sec., And a pulse width of 6 μsec.

In the present invention, the high-density polyethylene (A) is based on 100 parts by weight of the total amount of the high-density polyethylene (A) and the linear low-density polyethylene (B).
It is used in a proportion of 55 to 95 parts by weight, preferably 60 to 90 parts by weight, more preferably 60 to 85 parts by weight.

Linear low density polyethylene (B) Linear low density polyethylene (B) used in the present invention
Are ethylene homopolymers and ethylene / α-olefin copolymers of ethylene and α-olefins, preferably α-olefins having 3 to 12 carbon atoms.

Examples of the α-olefin having 3 to 12 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene,
Examples include 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. These may be copolymerized by one kind alone, or may be copolymerized by combining two or more kinds.

The linear low-density polyethylene (B) preferably used in the present invention is an ethylene / 1-butene copolymer,
Ethylene / 1-hexene copolymer, ethylene / 4-methyl-1
-It is a pentene copolymer or an ethylene / 1-octene copolymer.

This linear low-density polyethylene (B) is
The ethylene content is usually 95 to 99 mol%, preferably 96
The content of α-olefin as a comonomer is usually 1 to 5 mol%, preferably 2 to 4 mol%. If the ethylene content is within this range, there is heat resistance,
A film having excellent mechanical strength such as impact resistance can be obtained.

The composition of the linear low density polyethylene (B) is measured by the same method as described above. That is, the composition of linear low-density polyethylene is usually about 200 mg of linear low-density polyethylene in a 10 mmφ sample tube.
A ¹³ C-NMR spectrum of a sample uniformly dissolved in ml of hexachlorobutadiene was measured at a measurement temperature of 120 ° C., a measurement frequency of 25.05 MHz, a spectrum width of 1500 Hz,
The pulse repetition time is determined by measuring under a condition of 4.2 sec. And a pulse width of 6 μsec. The linear low-density polyethylene (B) used in the present invention has a density (measured in accordance with ASTM D-1505) of 0.890 to 0.925 g / cm ³ , preferably 0.895 to 0.925 g / cm ³ . cm ^3, more preferably in the range of 0.895~0.920g / cm ^3.
As long as the polyethylene (B) used in the present invention is within the above-mentioned density range, the main chain may have some short-chain or long-chain branches. In the present invention, a film having excellent mechanical strength such as impact resistance can be obtained by using the linear low-density polyethylene (B) having the above-mentioned density range.

The linear low density polyethylene (B) has a melt flow rate (MFR; ASTM D 1238 (1
(Measured in accordance with 90 ° C, load 2.16 kg)) is 0.5 to 10
g / 10 minutes, preferably 0.5 to 8 g / 10 minutes, more preferably 1.0 to 8.0 g / 10 minutes. The linear low-density polyethylene (B) was measured for weight average molecular weight (Mw) and number average molecular weight (Mn) by GPC at 140 ° C. column temperature using o-dichlorobenzene as a carrier. (Mw) divided by the number average molecular weight (Mn) is 1.5.
~ 3.5, and if it is within this range,
This shows that the low molecular weight component is small, and is suitable for use as a resin component inside the package.

The linear low-density polyethylene (B) used in the present invention is a single-site catalyst such as disclosed in
No. 9724, JP-A-6-136195, JP-A-6-136196, JP-A-6-207057, etc., containing a metallocene catalyst component (a). It can be prepared by homopolymerizing ethylene or copolymerizing ethylene with an α-olefin, preferably an α-olefin having 3 to 12 carbon atoms, in the presence.

Such a metallocene catalyst generally has at least one ligand having a cyclopentadienyl skeleton.
Metallocene catalyst component (a) composed of a transition metal compound of Group IVB of the periodic table, and organoaluminum oxy compound catalyst component (b), if necessary, particulate carrier (c), and organoaluminum compound catalyst component (d ), An ionized ionic compound formed from the catalyst component (e).

The metallocene catalyst component (a) preferably used in the present invention is a transition metal compound belonging to Group IVB of the periodic table having at least one ligand having a cyclopentadienyl skeleton. Examples of such a transition metal compound include a transition metal compound represented by the following general formula [I].

ML ¹ _x ... [I] In the formula, x is the valence of the transition metal atom M. M is a transition metal atom selected from Group IVB of the periodic table, specifically, zirconium, titanium, and hafnium, with zirconium being particularly preferred.

L ¹ is a ligand which coordinates to the transition metal atom M, and at least one of these ligands L ¹
Is a ligand having a cyclopentadienyl skeleton,
The cyclopentadienyl group may have a substituent such as a halogen atom or a trialkylsilyl group. Ligand L
Specific examples of ¹ include a cyclopentadienyl group, a methylcyclopentadienyl group, an n-butylcyclopentadienyl group, a dimethylcyclopentadienyl group, a trimethylcyclopentadienyl group, a tetramethylcyclopentadienyl group. Alkyl-substituted cyclopentadienyl group such as enyl group, pentamethylcyclopentadienyl group, methylethylcyclopentadienyl group, hexylcyclopentadienyl group, or indenyl group, 4,5,6,7-tetrahydroindenyl And fluorenyl groups.

When the compound represented by the general formula [I] contains two or more groups having a cyclopentadienyl skeleton, two of the groups having a cyclopentadienyl skeleton are methylene, ethylene, It may be bonded via an alkylene group such as propylene, a substituted alkylene group thereof, or a (substituted) silylene group such as a silylene group, a dimethylsilylene group, or a diphenylsilylene group.

The ligand L ¹ other than the ligand having a cyclopentadienyl skeleton includes an alkyl group such as a methyl, ethyl, propyl and butyl group, a cycloalkyl group such as a cyclopentyl group, an aryl group such as a phenyl group, It is an aralkyl group such as a benzyl group, an alkoxy group, an aryloxy group, a trialkylsilyl group, a hydrocarbon group containing a sulfonato group, a halogen atom or a hydrogen atom.

As the organoaluminum oxy compound catalyst component (b), a conventionally known aluminoxane obtained by reacting an alkylaluminum compound with water is preferably used. Aluminoxane has the general formula [-Al
(R) O-] _n (where R represents an alkyl group) a compound containing 3 to 50 repeating units, specifically, methylaluminoxane, ethylaluminoxane, methylethylaluminum Nooxane or the like is used.
The fine-particle carrier (c) used as needed in preparing the olefin polymerization catalyst is a conventionally known inorganic or organic compound, and preferably has a particle size of 20 to
It is a 200 μm granular or fine solid. A frequently used porous inorganic oxide alone is Si
O ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO ₂ , Ca
O, ZnO, BaO, SnO _{2 and the} like can be exemplified.

Examples of the organoaluminum compound catalyst component (d) include trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum; alkenylaluminums such as isoprenylaluminum; dialkylaluminum halides such as dimethylaluminum chloride and diethylaluminum chloride; An alkyl aluminum sesquihalide such as methyl aluminum sesquichloride is used.

The ionized ionic compound catalyst component (e) includes Lewis acids such as triphenylboron, MgCl ₂ , and Al ₂ O ₃ ; ionic compounds such as triphenylcarbenium tetrakis (pentafluorophenyl) borate;
Carborane compounds such as dodecaborane and the like are used.
Here, the atomic ratio (Al / M) between the aluminum atom (Al) derived from the component (b) and / or the component (c) and the transition metal atom (M) derived from the component (a) is 5 to 5. 3
The range of 00 is preferable, and the range of 10 to 200 is particularly preferable.

The linear low-density polyethylene (B) used in the present invention can be prepared under various conditions in the presence of a catalyst containing a metallocene compound as described above in a gas phase or a slurry or solution liquid phase. Can be obtained by homopolymerizing ethylene or copolymerizing ethylene with an α-olefin.

In the slurry polymerization method or the solution polymerization method, an inert hydrocarbon may be used as a solvent, or an olefin itself may be used as a solvent. In the present invention, in the preparation of the linear polyethylene (B), if necessary, (1) multi-stage polymerization, (2) multi-stage polymerization of liquid phase and gas phase, or
(3) It is possible to adopt a method such as performing preliminary polymerization in a liquid phase and then performing polymerization in a gas phase. The linear low-density polyethylene (B) produced using these catalyst systems is:
Usually, since the polymerization activity on the catalyst surface is single, the molecular weight distribution (Mw / Mn) of polyethylene is narrow and the composition distribution is uniform as described above.

The linear low-density polyethylene (B) obtained by these methods uses o-dichlorobenzene as a carrier and has a weight average molecular weight (Mw) and a number average molecular weight (Mn) by a GPC method at a column temperature of 140 ° C. ) Was measured, the weight average molecular weight (Mw) was converted to the number average molecular weight (Mw).
The value (Mw / Mn) divided by n) is desirably 1.5 to 3.5, and if it is within this range, it indicates that the low molecular weight component is small, and as a resin component inside the package, Suitable for use.

Resin composition for sealant The resin composition for sealant of the retort film according to the present invention contains the above-mentioned high-density polyethylene (A), linear low-density polyethylene (B) and, if necessary, other components described above. doing.

The mixing ratio of the high-density polyethylene (A) and the linear low-density polyethylene (B) is such that the high-density polyethylene (A) is 55 parts by weight based on 100 parts by weight of the total amount of (A) and (B). -95 parts by weight, preferably 60-9
0 parts by weight, more preferably 60 to 85 parts by weight,
5 to 45 parts by weight of the linear low density polyethylene (B),
Preferably 10 to 40 parts by weight, more preferably 15 to
40 parts by weight.

By mixing the linear low-density polyethylene (B) with the high-density polyethylene (A) in the above ratio, the film obtained can be compared with a film prepared from only the high-density polyethylene (A). Thus, the haze is reduced, that is, the transparency is improved, the flexibility is increased, and the decrease in impact strength is small.

In the present invention, the linear low-density polyethylene (B) prepared in the presence of a metallocene-based catalyst is replaced with the linear low-density polyethylene (B) prepared in the presence of a conventionally used Ti-based Ziegler catalyst. When low-density polyethylene is used, the resulting film can achieve an improvement in transparency, but has a large decrease in impact strength.

Other Ingredients The resin composition for a sealant of a retort film according to the present invention contains an antioxidant, a heat stabilizer, an antistatic agent, an anti-slip agent and an anti-blocking agent as long as the object of the present invention is not impaired. If necessary, additives such as anti-fogging agents, lubricants, pigments, dyes, nucleating agents, plasticizers, anti-aging agents, hydrochloric acid absorbents, and weather stabilizers may be added in appropriate amounts. Further, a small amount of another resinous or elastomeric polymer compound can be blended without departing from the object of the present invention.

The resin composition for a sealant of a retort film according to the present invention has a film impact strength at −5 ° C. (measured using a film impact tester manufactured by Toyo Seiki Seisaku-sho, Ltd.) of 1200 kg · cm / cm or more (for example, 1200 to 1200 kg / cm). 7000 kg · cm / cm), the film has a haze (ASTM D 1003-61) of 5.5% or less (for example, 1 to 5.5%) after boiled at 120 ° C. for 1800 seconds, and heat -2 of seal part
Tensile breaking strength at 0 ° C (seal strength) is 20N /
15 mm or more (for example, 20 to 50 N / 15 mm),-
Elongation at break at 20 ° C. (seal elongation) of 200
% Is preferable. A film having a higher tensile elongation at break is easier to absorb impact and has better low-temperature impact resistance.

The tensile strength at break and the tensile elongation at break were determined by heat-sealing the film with a Neurong HS-33D top sealer (trade name, manufactured by Tester Sangyo Co., Ltd.), and then performing a constant crosshead moving speed tensile test. It is measured by performing a tensile test in a -20 ° C atmosphere using a machine (manufactured by Instron).

Preparation of Resin Composition for Sealant The resin composition for sealant of the retort film according to the present invention is prepared from the high-density polyethylene (A) and the linear low-density polyethylene (B) by a known method. Can be manufactured. Specifically, for example, the following method can be mentioned. (1) A high-density polyethylene (A), a linear low-density polyethylene (B), and other components added as necessary,
Dry blending method using Henschel mixer, etc.,
A method of mechanically melt-blending using an extruder, a kneader or the like, or a blending method using these methods in combination. (2) The high-density polyethylene (A), the linear low-density polyethylene (B), and other components added as necessary,
Suitable good solvents (eg hexane, heptane, decane,
A solvent such as cyclohexane, benzene, toluene and xylene) and then removing the solvent. (3) A solution is prepared by separately dissolving the high-density polyethylene (A), the linear low-density polyethylene (B), and other components added as necessary in a suitable good solvent. A method of mixing the above solutions and then removing the solvent. (4) A method in which the above methods (1) to (3) are combined.

Further, in addition to the above method, a resin composition for a sealant can be produced by the following method. For example, one polymerization vessel is used to conduct polymerization under different reaction conditions.
It can be produced by polymerizing a linear low density polyethylene (B) and a high density polyethylene (A) in stages or more. Specifically, by a two-stage polymerization process, the linear low-density polyethylene (B) is polymerized in the first stage,
It can be produced by polymerizing the high-density polyethylene (A) in the subsequent stage, or polymerizing the high-density polyethylene (A) in the preceding stage and polymerizing the linear low-density polyethylene (B) in the subsequent stage. Alternatively, high-density polyethylene (A), linear low-density polyethylene (B) in separate polymerization vessels
Can be obtained by mixing and mixing them.

Further, a plurality of polymerization reactors are used, and one of the polymerization reactors is used to polymerize the linear low-density polyethylene (B). The high-density polyethylene (A) is polymerized in the first polymerization vessel, or the high-density polyethylene (A) is polymerized in one polymerization vessel, and then in the other polymerization vessel in the presence of the high-density polyethylene (A). It can also be produced by polymerizing high density polyethylene (B).

The sealant film for a retort film The sealant film for a retort film according to the present invention comprises a composition containing the above-described high-density polyethylene (A) and linear low-density polyethylene (B). . This film can be produced by, for example, an inflation method or a T-die method,
Its thickness is preferably 10 to 100 μm, particularly preferably 30 to 80 μm.

The sealant film for a retort film according to the present invention has a film impact strength at −5 ° C. (measured using a film impact tester manufactured by Toyo Seiki Seisaku-Sho, Ltd.) of 1200 kg · cm / cm or more (eg, 1200 to 7000 kg · cm). / Cm),
The film has a haze (ASTM D 1003-61) of 5.5% or less (for example, 1%) after boiled at 120 ° C. for 1800 seconds.
５5.5%) and -20 ° C. of the heat-sealed part.
Tensile strength at break (seal strength) of 20N / 15
mm or more (for example, 20 to 50 N / 15 mm), -20
A film having a tensile elongation at break (seal elongation) at 200C of 200% or more is preferable. Films with better tensile elongation at break readily absorb significant impact,
Moreover, it shows better low-temperature impact resistance. After the film was heat-sealed with a NEWLONG HS-33D top sealer (trade name: manufactured by Tester Sangyo Co., Ltd.),
It is measured by performing a tensile test in an atmosphere of −20 ° C. using a tensile tester (manufactured by Instron) with a constant crosshead moving speed. In this case, the heat sealing is performed at a sealing temperature of 130 ° C., a sealing time of 1 second, and a sealing pressure of 0.2 MPa.

Preparation of Sealant Film The sealant film for a retort film according to the present invention as described above is obtained by preparing the above-described resin composition for a sealant from:
For example, it can be prepared by film formation by an inflation method or a T-die extrusion method.

The film forming by the inflation method is performed by extruding the raw resin composition through a circular die and expanding the resin composition by a predetermined air flow. The resin temperature at the time of extruding the raw resin composition of the present invention is preferably 190 to 250 ° C. The film forming method by the T-die extrusion method is performed by extruding a raw resin composition in a molten state from a T-die, and winding up the extruded film. For example, 600
Toshiba Unimelt extruder equipped with a T-die of mm width (diameter:
65 mm), the raw resin composition is extruded from a T-die at a resin temperature of 230 ° C. and a resin pressure of 180 kg / cm ² , and then the extruded film is wound at a speed of 20 m / min.

The sealant film formed by the above method can be laminated on a substrate to form a retort film. Further, a retort pouch can be manufactured by heat-sealing the periphery of the film cut into the predetermined shape. The base material used is a metal foil such as an aluminum foil, a metal vapor-deposited film, a polyester film such as polyethylene terephthalate, a polyamide, an ethylene-vinyl alcohol copolymer, a single layer having excellent gas barrier properties such as polyvinylidene chloride. Or a multilayer polymer film. The polymer film may be in any state of biaxially stretched, uniaxially stretched, or unstretched.

The retort film may be produced by directly extruding and laminating a resin composition for a sealant on a substrate in the form of a film, or by dry laminating the above-mentioned sealant film on a substrate via an anchor coat agent. . At this time, the thickness of the sealant layer is
It is sufficient that the pouch has a thickness enough to exhibit sufficient heat sealing strength at the time of pouch production, preferably from 10 to 100.
μm, particularly preferably 30 to 80 μm. When a transparent type retort pouch is obtained, examples of the layer structure include a laminated structure of a polyamide film / sealant film, a polyethylene terephthalate / sealant film, or the like.

When a retort pouch containing an aluminum foil is obtained, its layer structure is, for example, aluminum foil / sealant film, polyethylene terephthalate film / aluminum foil / sealant film, polyethylene terephthalate film / polyamide film / aluminum foil / sealant film, etc. Can be exemplified.

[0053]

The resin composition for a sealant of a retort film according to the present invention has excellent low-temperature impact resistance,
A sealant film for a retort film having excellent high-temperature transparency, heat-fusing property, heat-deformability, and seal strength characteristics can be formed.

The sealant film for a retort film according to the present invention is excellent in low-temperature impact resistance and excellent in high-temperature transparency, heat-fusible properties, heat-resistant deformation properties and seal strength properties because it is made of the above composition. Therefore, even when the retort pouch using the sealant film according to the present invention is heat-sterilized at 100 to 125 ° C., whitening (decrease in transparency) on the sealing surface, heat fusion, thermal deformation, and breakage of the seal occur. In addition, the bag can be prevented from breaking even if the retort pouch falls under a low temperature, for example, in a -5 ° C atmosphere.

Therefore, the above-mentioned effects are obtained.
The resin composition for a sealant of a retort film and the sealant film according to the present invention are suitable for applications such as retort food packaging containers such as large-scale retort pouches for business use and medical containers such as infusion bags.

[0056]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The test methods for the physical properties of the sealant films obtained in Examples and Comparative Examples are as follows. (1) Film impact strength at −5 ° C. (low-temperature impact resistance) The film impact strength at −5 ° C. was measured using a film impact tester manufactured by Toyo Seiki Seisaku-sho, Ltd. (2) Haze (Transparency) After the sealant film was boiled at 120 ° C. for 1800 seconds, the haze before the treatment was measured according to ASTM D 1003-61. (3) Tensile strength at break and tensile elongation at break (seal strength characteristics)
HS-33D Top Sealer [Product name, manufactured by Tester Sangyo Co., Ltd.]
After heat-sealing the film under the conditions of a sealing temperature of 140 ° C., a sealing time of 1 second, and a sealing pressure of 0.2 MPa, a -20 ° C. atmosphere using a constant crosshead moving speed tensile tester (manufactured by Instron). It was measured by performing a tensile test below.

The linear low-density polyethylene used in the examples and comparative examples is shown in Table 1. The linear low-density polyethylenes (1) to (4) shown in Table 1 are bis (1,3-dimethylcyclopentadienyl) zirconium dichloride,
It was prepared by gas phase polymerization of ethylene with 1-octene or 1-hexene in the presence of a metallocene catalyst prepared from methylaluminoxane and triisobutylaluminum.

The linear low-density polyethylene (5) shown in Table 1 is a polyethylene obtained by polymerizing ethylene and 4-methyl-1-pentene in the presence of a Ziegler catalyst. The high-density polyethylene (HDPE) shown in Table 1 was produced by a low-pressure polymerization method using a Ziegler catalyst. Polypropylene (PP) was obtained by homopolymerizing propylene in the presence of a Natta catalyst.

[0060]

[Table 1]

[0061]

EXAMPLES 1-4 High-density polyethylene prepared by low-pressure polymerization using the Ziegler catalyst shown in Table 1 and linear low-density polyethylene prepared in the presence of a metallocene-based catalyst are shown in Table 2. The mixture was mixed using a Henschel mixer at the ratio shown in Table 2, and the mixture was kneaded with an extruder to form pellets.

Further, the obtained resin composition (I) was molded by a casting method under the following molding conditions, and a thickness of 60 μm was obtained.
m, a film having a width of 400 mm was obtained. [Molding conditions] Molding machine: Unimelt 65 mmφ cast molding machine manufactured by Toshiba Machine Co., Ltd. Die diameter: 500 mm (diameter) Molding temperature: cylinder 200 ° C., die 210 ° C. Take-off speed: 20 m / min Film obtained as above , The film impact strength, the haze, the tensile break strength at the seal portion and the tensile break elongation were measured by the methods described above. Table 2 shows the results.

[0063]

Comparative Example 1 In Example 1, a resin having a thickness of 60 as shown in Table 1 was used instead of the resin composition (I).
The above physical properties were measured in the same manner as in Example 1 except that a μm film was used. Table 2 shows the results.

[0064]

Comparative Example 2 In Example 1, a linear low-density polyethylene [LL] shown in Table 1 was used instead of the resin composition (I).
A film having a thickness of 60 μm was formed in the same manner as in Example 1 except that DPE (5) was used. The physical properties of the obtained film were measured in the same manner as in Example 1. Table 2 shows the results.

[0065]

Comparative Example 3 A film having a thickness of 60 μm was formed in the same manner as in Example 1, except that only the high-density polyethylene (HDPE) was used instead of the resin composition (I). The physical properties of the obtained film were measured in the same manner as in Example 1. Table 2 shows the results.

[0066]

Comparative Example 4 In Example 1, a linear low-density polyethylene (LLDPE) was used instead of the resin composition (I).
Except for using only (1)), in the same manner as in Example 1,
A film having a thickness of 60 μm was formed. The physical properties of the obtained film were measured in the same manner as in Example 1. Table 2 shows the results.

[0067]

Comparative Example 5 In Example 1, the high-density polyethylene 3
0 parts by weight and linear low density polyethylene (LLDPE
(2) A film having a thickness of 60 μm was formed in the same manner as in Example 1 from 70 parts by weight of the mixture. The physical properties of the obtained film were measured in the same manner as in Example 1. Table 2 shows the results.

[0068]

[Table 2]

Claims (7)

[Claims] (A) a density of 0.945 to 0.970 g /
cm ³ , melt flow rate (ASTM D 1238, 190 ° C, load 2.16k
g) having a density of 0.890 to 0.925 g / cm ³ , prepared using 55 to 95 parts by weight of a high-density polyethylene having a density of 0.5 to 10 g / 10 min and (B) a metallocene-based catalyst. Yes, melt flow rate (ASTM D 1238, 190 ℃, load 2.16k
g) contains 0.5 to 45 parts by weight of a linear low-density polyethylene having a weight of 0.5 to 10 g / 10 minutes [the total amount of components (A) and (B) is 100 parts by weight]. A resin composition for a sealant for a retort film. 2. The linear low-density polyethylene (B) comprises 95 to 99 mol% of an ethylene component and α of 3 to 12 carbon atoms.
-Ethylene / α comprising 1 to 5 mol% of an olefin component
-An olefin copolymer, characterized in that it is an olefin copolymer.
3. The resin composition for a sealant according to item 1. 3. The linear low-density polyethylene (B) having a weight average molecular weight (Mw) / number average molecular weight (Mn) value of 1.5 to 3.5. The resin composition for a sealant as described above. 4. The film impact strength at -5.degree. C. is 1200 kg.cm/cm or more,
The haze of the film after boiled for 00 seconds is 5.5
% Or less, and a resin composition capable of forming a film having a tensile strength at break at −20 ° C. of not less than 20 N / 15 mm and a tensile elongation at break at −20 ° C. of 200% or more of the heat-sealed portion. The resin composition for a sealant of a retort film according to claim 1, wherein: (A) a density of 0.945 to 0.970 g /
cm ³ , melt flow rate (ASTM D 1238, 190 ° C, load 2.16k
g) having a density of 0.890 to 0.925 g / cm ³ , prepared using 55 to 95 parts by weight of a high-density polyethylene having a density of 0.5 to 10 g / 10 min and (B) a metallocene-based catalyst. Yes, melt flow rate (ASTM D 1238, 190 ℃, load 2.16k
g) is a resin composition comprising 5-45 parts by weight of a linear low-density polyethylene having a weight of 0.5 to 10 g / 10 minutes [the total amount of components (A) and (B) is 100 parts by weight]. A sealant film for a retort film, which is a film formed of a product. 6. The film impact strength at -5 ° C. is not less than 1200 kg · cm / cm, and
The haze of the film after boiled for 00 seconds is 5.5
% Or less, and a film having a tensile strength at break at -20 ° C. of not less than 20 N / 15 mm and an elongation at break at −20 ° C. of 200% or more. 6. The sealant film for a retort film according to 5. 7. The sealant film according to claim 5, wherein the sealant film is laminated on one side of a polyamide film, a polyester film or an aluminum foil.