JPH083384A - Resin composition for food packaging film and food packaging film - Google Patents

Abstract

(57) [Summary] (Corrected) [Constitution] 10 to 95% by weight of the following (A) component and (B)
A resin composition obtained by uniformly melt-kneading 90 to 5% by weight of components. Component (A): made of ethylene and α-olefin having 3 to 12 carbon atoms and having a density of 0.900 to 0.940 g / cm 3.
³ , the ethylene / α-olefin copolymer (B) component having a maximum melting peak temperature of 110 ° C. as measured by a differential scanning calorimeter: composed of ethylene and α-olefin having 3 to 12 carbon atoms and having a density of 0. 880 to 0.920 g / cm
³ , the molecular weight distribution represented by the ratio of weight average molecular weight / number average molecular weight is 1.8 to 3.0, and the maximum melting peak temperature measured by a differential scanning calorimeter is within the range of 60 to 110 ° C. Ethylene / α-olefin copolymer [Effect] In addition to mechanical strength such as impact strength, tensile strength and tear strength, it has the performance required as a food packaging material such as low temperature heat sealability and food hygiene. .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition for a food packaging film and a food packaging film.

[0002]

2. Description of the Related Art Most of packaging materials are ethylene resins such as polyethylene, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers from the viewpoint of excellent heat-sealing property, hot tack property and food hygiene property. , Ionomers, etc. are used as the heat seal layer. At present, in which packaging forms have been diversified, in order to sufficiently satisfy the performance required for materials, many of them take a form in which an ethylene polymer resin is laminated on another suitable film. For example, films such as stretched polyamide and polyethylene terephthalate are often used as base materials for food packaging materials, but they are heat sealable even though they are excellent in many aspects such as impact strength, rigidity, gas barrier properties and safety and hygiene. It has the drawback of being inferior in properties. On the other hand, the polyolefin resin film alone has good heat-sealing properties, but is inferior to the above-mentioned base film in terms of impact strength and rigidity. Generally, a method of stacking is used to complement the defects of both.

In addition to mechanical strength such as impact strength, tensile strength and tear strength, the above ethylene-based copolymers used for food packaging materials have low temperature heat sealing property, hot tack property and food hygiene property. Nature is required.

Many materials have been proposed so far as an ethylene resin used for a heat seal layer of a food packaging material. However, the conventional one is unsatisfactory in heat sealability at low temperature. Further, in the case of a material having excellent heat-sealing property and hot tack property, some of the components in the ethylene-based resin migrate into the food depending on the food to be packaged, which causes a food hygiene problem. Especially when the food is oily, it is difficult to use. It should be noted that the amount of extraction with respect to n-hexane is usually used as an index showing the degree of migration of the components in the ethylene resin into food.

[0005]

Generally, in order to improve the low-temperature heat-sealing property and hot-tack property of the ethylene-based copolymer, a means for lowering the density of the ethylene-based resin is used, which is packaged. It increases the amount of ingredients transferred to foods, which adversely affects food hygiene. vice versa,
If the density is increased in order to reduce the amount of transferred components, the low temperature heat sealability will be deteriorated.

The present invention is intended to provide a composition suitable as a food packaging material and a film thereof. Specifically, in addition to mechanical strength such as impact strength, tensile strength and tear strength, low temperature heat An object of the present invention is to obtain a resin composition for a food packaging film having the performance required as a food packaging material such as sealing property and food hygiene, and the film.

[0007]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that these problems can be solved by melt-mixing a specific ethylene / α-olefin copolymer. It was solved, and it was found that a resin composition and a film thereof having excellent mechanical properties, low extractability by a hydrocarbon solvent, and good low-temperature sealing property and hot tack property can be obtained.

That is, one aspect of the present invention is the following (A) component 10 to 95% by weight and (B) component 90 to 5:
A resin composition obtained by uniformly melt-kneading wt%, wherein the density is 0.890 to 0.920 g / cm ³ ,
It relates to a resin composition for a food packaging film, which has a melt flow rate of 0.5 to 20 g / 10 minutes at a temperature of 190 ° C. and a load of 2.16 kg and an n-hexane soluble content of 6% by weight or less. .

Component (A): ethylene and 3 to 12 carbon atoms
Made of α-olefin, and has a density of 0.900 to 0.9
40 g / cm ³ , temperature 190 ° C., load 2.16 k
Ethylene / α-olefin copolymer having a melt flow rate in g of 0.5 to 30 g / 10 min and a maximum melting peak temperature of 110 ° C. as measured by a differential scanning calorimeter

Component (B): ethylene and 3 to 12 carbon atoms
Of α-olefin, and has a density of 0.880 to 0.9.
20 g / cm ³ , temperature 190 ° C., load 2.16 k
The melt flow rate in g is 0.5 to 30 g / 10 minutes, the number average molecular weight measured by the GPC method is 35,
000 to 150,000, and the molecular weight distribution represented by the ratio of weight average molecular weight / number average molecular weight is 1.8 to 3.0.
And the maximum melting peak temperature measured by a differential scanning calorimeter is within the range of 60 to 110 ° C.
Olefin copolymer

Another aspect of the present invention relates to a food packaging film using the above resin composition for a food packaging film.

The details will be described below.

The component (A) of the present invention comprises ethylene and an α-olefin having 3 to 12 carbon atoms and has a density of 0.90.
0 to 0.940 g / cm ³ and a melt flow rate of 0.5 to ³⁰ g at a temperature of 190 ° C. and a load of 2.16 kg.
It is an ethylene / α-olefin copolymer having a maximum melting peak temperature of 110 minutes and a maximum melting peak temperature of 110 ° C. as measured by a differential scanning calorimeter.

The carbon number of the α-olefin as the component (A) is 3
-12, preferably 6-12. Specific examples of the α-olefin include propylene, butene-1, pentene-
Examples thereof include 1,4-methylpentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1. These may be used alone or in combination of two or more.
Of these, particularly preferred are propylene, butene-1, 4-methylpentene-1, hexene-1, 4-methylhexene-1 and octene-1, and the most preferred are butene-1 and hexene-1. Is.

The content ratio of the α-olefin in the component (A) is preferably 1 to 20 mol%. When the content ratio is too small, the density of the component (A) may be too small, while when the content ratio is too large, the density of the component (A) may be too large.

The density of the component (A) is 0.900 to 0.94.
0 g / cm ³ , preferably 0.902 to 0.920 g /
It is cm ³ . If the density is too low, the n-hexane-soluble content of the finally obtained resin composition will increase, causing problems in food hygiene and causing stickiness in the film, and blocking will easily occur. On the other hand, when the density is too high, the flexibility of the obtained resin composition film is insufficient and the low temperature heat sealability is deteriorated.

Component (A) temperature 190 ° C., load 2.16
Melt flow rate in kg is 0.5 to 30 g / 10
Min, preferably 1.0 to 10 g / 10 min. If the melt flow rate is too small, the resin pressure of the extruder becomes large when the resin composition finally obtained for obtaining a film for food packaging is subjected to extrusion processing, resulting in a significant decrease in extrusion processability. On the other hand, if the melt flow rate is too high, take-up surging tends to occur during extrusion, which is not preferable in terms of film forming property, and a satisfactory film for food packaging cannot be obtained. Here, the melt flow rate is
It is measured by the method specified in Condition 4 of Table 1 of JIS-K7210.

The maximum melting peak temperature of the component (A) measured by a differential scanning calorimeter is higher than 110 ° C, preferably higher than 115 ° C. If this condition is not satisfied, the n-hexane soluble content will increase.

The component (A) preferably has two or more endothermic peaks measured by a differential scanning calorimeter. This makes it possible to achieve an excellent balance between the low temperature heat sealability and the mechanical strength of the final composition obtained.

Here, the maximum melting peak temperature measured by a differential scanning calorimeter is JIS K71 using a differential scanning calorimeter (for example, 7 type DSC device manufactured by Perkin Elmer Co.).
22 to obtain the amount of heat of fusion. The measuring method conforms to K7121 3- (2).

The component (A) is an ethylene / α-olefin copolymer satisfying the above conditions.

As a specific method for obtaining the component (A), the presence of a catalyst composed of a solid catalyst component containing at least a transition metal and an organoaluminum compound compound is generally used by an ionic polymerization method using ethylene and α-olefin. Under normal conditions of 30 to 300 ° C., normal pressure to 3000 kg / cm ² ,
Polymerization in the presence of a solvent, gas-solid, liquid-solid or homogeneous liquid phase,
Manufactured. Examples of the solid catalyst component containing a transition metal include titanium compounds such as chromium oxide, molybdenum oxide, titanium trichloride, titanium tetrachloride, titanium tetrachloride-alkylaluminum and titanium tetrachloride-magnesium compounds such as magnesium chloride compounds- Examples thereof include (chlorinated) alkylaluminum compounds.

The component (B) of the present invention comprises ethylene and an α-olefin having 3 to 12 carbon atoms and has a density of 0.88.
0 to 0.920 g / cm ³ and a melt flow rate of 0.5 to ³⁰ g at a temperature of 190 ° C. and a load of 2.16 kg.
/ 10 minutes, the number average molecular weight measured by the GPC method is 35,000 to 150,000, and the molecular weight distribution represented by the ratio of weight average molecular weight / number average molecular weight is 1.
It is an ethylene / α-olefin copolymer having a maximum melting peak temperature of 8 to 3.0 and a maximum melting peak temperature observed by a differential scanning calorimeter of 60 to 110 ° C.

The carbon number of the α-olefin of the component (B) is 3
-12, preferably 6-12. Specific examples of the α-olefin include those mentioned above as the α-olefin of the component (A). In addition, α of the component (A)
The olefin and the α-olefin of the component (B) may be the same or different.

The content ratio of the α-olefin in the component (B) is preferably 5 to 40 mol%. When the content ratio is too low, the density of the component (B) may be too high, while when the content ratio is too high, the density of the component (B) may be too low.

The density of the component (B) is 0.880 to 0.92.
0 g / cm ³ , preferably 0.890 to 0.915 g /
It is cm ³ . If the density is too low, the n-hexane-soluble content of the finally obtained resin composition increases to cause a problem in food hygiene, and the film becomes sticky, and blocking is likely to occur. On the other hand, if the density is too high, the resulting resin composition film lacks in flexibility, lowers the low-temperature heat-sealing property, and deteriorates the feel as a film for food packaging.

Component (B) temperature 190 ° C., load 2.16
Melt flow rate in kg is 0.5 to 30 g / 10
Min, preferably 1.0 to 20 g / 10 min. When the melt flow rate is too small, the resin pressure of the extruder becomes large when the resin composition finally obtained is extruded in order to obtain the film for food packaging of the present invention, and the extrudability is lowered. . On the other hand, if the melt flow rate is too high, take-up surging tends to occur during extrusion, which is not preferable in terms of film forming property, and a satisfactory film for food packaging cannot be obtained. The melt flow rate is measured by the method specified in Condition 4 of Table-1 of JIS-K7210.

The component (B) has a number average molecular weight of 35,000 to 150,000, preferably 60,000 to 110,000, as measured by the GPC method. If the number average molecular weight is too small, take-up surging is likely to occur during extrusion processing, which is not preferable in terms of film forming property, and a satisfactory film for food packaging cannot be obtained. On the other hand, when the number average molecular weight is too large, the resin pressure of the extruder becomes large when the resin composition finally obtained in order to obtain the film for food packaging is extruded, and the extrudability is deteriorated.

The molecular weight distribution represented by the ratio of the weight average molecular weight / number average molecular weight of the component (B) is 1.8 to 3.0, preferably 1.9 to 2.5. If the ratio is too small, the molding load becomes difficult due to the increase in motor load during extrusion molding,
On the other hand, if the ratio is too large, the moldability improves, but
Satisfactory heat seal characteristics cannot be obtained.

The component (B) has a maximum melting peak temperature measured by a differential scanning calorimeter of 60 to 110 ° C., preferably 80 to 1
It is observed in the range of 00 ° C, most preferably 85 to 95 ° C. If the temperature is too low, the n-hexane soluble content becomes excessive, while if the temperature is too high, the low temperature heat sealability is poor.

The component (B) may have one or more endothermic peaks as measured by a differential scanning calorimeter, but preferably has only one endothermic peak. This can further improve the low temperature heat sealability.

Here, the maximum melting peak temperature measured by a differential scanning calorimeter is measured by the method described in the section for the component (A).

The component (B) is an ethylene / α-olefin copolymer satisfying the above conditions.

The component (B) is generally produced by an ionic polymerization method in the presence of a metallocene catalyst or a Ziegler catalyst, usually at 30 to 300 ° C., atmospheric pressure to 3000 kg / cm ² ,
It is produced in the presence of a solvent or without a solvent, in a gas-solid, liquid-solid or homogeneous liquid phase.

The metallocene compound is a composite catalyst system of a compound having a specific structure containing a transition metal and an oxygen-containing organoaluminum compound, and the Ziegler catalyst is a composite catalyst system of a vanadium compound and an organoaluminum compound. To be

The metallocene catalyst is represented by the general formula R ¹ _k
R ² _l R ³ _m R ⁴ _n M (wherein M is zirconium, titanium, hafnium or vanadium, R ¹ is a group having a cycloalkadienyl skeleton, and R ² , R ³ and R ⁴ are cycloalkaline). A group having a dienyl skeleton, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a halogen atom or hydrogen, k and l are integers of 1 or more, and k +
1 + m + n = 4. ), 1. 1. a transition metal compound containing a ligand having a cycloalkadienyl skeleton, and A catalyst system composed of a compound mainly containing an organoaluminum oxide compound can be mentioned.

For example, the following compounds are used as the transition metal compound containing a ligand having a cycloalkadienyl skeleton. Examples of the transition metal compound containing a ligand having a cycloalkadienyl skeleton include bis (cyclopentadienyl) diethyltitanium, bis (cyclopentadienyl) dimethyltitanium, bis (pentamethylcyclopentadienyl) titanium, and bis (Cyclopentadienyl) dichlorotitanium, bis (cyclopentadienyl) titanium monochloride monohydride, bis (indenyl) titanium monochloride monohydride, bis (indenyl) titanium dichloride, ethylenebis (indenyl) dimethyltitanium, ethylenebis ( Indenyl) methyltitanium chloride, ethylenebis (indenyl) titanium dichloride, ethylenebis (4,5,6,7-tetrahydro-1-indenyl)
Titanium dichloride, ethylene bis (4,5,6,7
-Tetrahydro-1-indenyl) dimethyltitanium, ethylenebis (4-methyl-1-indenyl) titanium dichloride, ethylenebis (2,3-dimethyl-
1-indenyl) titanium dichloride, bis (cyclopentadienyl) diethyltitanium, bis (cyclopentadienyl) dimethylzirconium, bis (pentamethylcyclopentadienyl) zirconium, bis (cyclopentadienyl) dichlorozirconium, bis ( Cyclopentadienyl) monochloride monohydride, bis (indenyl) zirconium monochloride monohydride, bis (indenyl) zirconium dichloride,
Ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) methylzirconium dichloride, ethylenebis (indenyl) zirconium dichloride, ethylenebis (4,5,6,7-tetrahydro-1)
-Indenyl) zirconium dichloride, ethylenebis (4,5,6,7-tetrahydro-1-indenyl) dimethylzirconium, ethylenebis (4-methyl-1-)
Examples thereof include indenyl) zirconium dichloride and ethylenebis (2,3-dimethyl-1-indenyl) zirconium dichloride. Preferably, biscyclopentadienyldimethyltitanium, bispentadienyltitanium dichloride, biscyclopentadienyldimethylzirconium and bispentadienylzirconium dichloride are used. As the oxygen-containing organoaluminum compound, tetramethyldialuminoxane, tetraethyldiaminoxane, tetrabutyldialuminoxane,
Tetrahexyl dialuminoxane, methyl aluminoxane, ethyl aluminoxane, butyl aluminoxane, hexyl aluminoxane, etc. are mentioned. Of these, methylaluminoxane is preferably used.

Compound of vanadium compound and organoaluminum
As a catalyst system composed of a substance, a general formula VO (OR)_nX
_3-n(However, R is a hydrocarbon group, X is a halogen, and 0 ≦ n ≦
3 is shown. ), VOCl₃, VO (O
CH₃) Cl₂, VO (OCH ₃)₂Cl, VO (OC
H₃)₃, VO (OC₂H_Five) Cl₂, VO (OC₂H
_Five)₂Cl, VO (OC₂H_Five)₃, VO (OC
₃H₇) Cl₂, VO (OC₃H₇)₂Cl, VO (O
C₃H₇)₃, VO (OisoC₃H₇) Cl₂, VO
(OisoC₃H₇)₂Cl, VO (OisoC
₃H₇)₃Alternatively, it is possible to exemplify these mixtures.
Wear. Of these compounds, compounds represented by 0 ≦ n ≦ 1
Compounds are particularly preferably used. Organic aluminization
As a compound, the general formula R ^' _mAlX_3-m(However, R'is
Hydrocarbon group, X is halogen, and 1≤m≤3.
You ), (C₂H_Five)₂AlCl, (C
_FourH₉)₂AlCl, (C ₆H₁₃)₂AlCl, (C₂
H_Five)_1.5AlCl_1.5, (C_FourH₉)_1.5AlCl
_1.5, (C₆H₁₃)_1.5AlCl_1.5, C₂H_FiveAlC
l₂, C_FourH₉AlCl₂, C₆H₁₃AlCl₂etc
It can be illustrated. Demonstrate more favorable effects in the present invention
To satisfy this, 1 ≦ m ≦ 2 is satisfied, and in particular (C
₂H_Five)_1.5AlCl_1.5Is preferably used.

With these metallocene compound / oxygen-containing organoaluminum compound catalyst system or vanadium compound / organoaluminum compound catalyst system, an ethylene / α-olefin copolymer having a narrower molecular weight distribution and a uniform composition distribution can be obtained. The resin composition of the present invention can be obtained.

The resin composition for a food packaging film of the present invention comprises 10 to 95% by weight of the above-mentioned component (A) and component 9 (B).
A resin composition obtained by uniformly melt-kneading 0 to 5% by weight, having a density of 0.890 to 0.920 g / cm ³ and a melt flow rate at a temperature of 190 ° C. and a load of 2.16 kg. It is 0.5 to 20 g / 10 minutes, and the n-hexane soluble content is 6% by weight or less.

In the resin composition, the component (A) is 10 to
95% by weight, preferably 30 to 90% by weight, most preferably 50 to 85% by weight, and the component (B) is 90 to 5% by weight, preferably 70 to 10% by weight, most preferably 5%.
It is 0 to 15% by weight. If the component (A) is too small (the component (B) is too large), the mechanical strength of the film may be reduced,
If the component (A) is too large (the component (B) is too small), the heat seal strength at low temperature, which is the object of the present invention, will not be satisfactory.

The components (A) and (B) are melt-kneaded. The method of melt kneading is not limited, but for example, a method of uniformly mixing the pellets of the component (A) and the component (B) and then uniformly melt kneading using an extruder can be used.

The resin composition has a density of 0.890 to 0.92.
0 g / cm ³ , preferably 0.895 to 0.915 g /
It is cm ³ . If the density is too low, the solvent extractability becomes high, resulting in poor food hygiene and poor film blocking properties. On the other hand, if the density is too high, satisfactory low-temperature heat sealability cannot be obtained, and problems such as film breakage during extrusion molding tend to occur.

Resin composition temperature 190 ° C., load 2.16
Melt flow rate in kg is 0.5 to 20 g / 10
Min, preferably 1.0 to 10 g / 10 min. If the melt flow rate is too low, the resin pressure at the time of extrusion molding rises and the motor load becomes excessive, which is not preferable. On the other hand, if the melt flow rate is too high, problems such as surging are likely to occur during extrusion molding.

The n-hexane soluble content of the resin composition is 6% by weight or less. When the soluble content is excessive, some components in the resin composition are transferred to the food to be packaged,
This may cause problems in food hygiene, cause stickiness on the film surface, cause blocking, and impair heat seal properties and hot tack properties. The n-hexane soluble content is preferably 5% by weight or less in consideration of the heat-sealing property, other mechanical properties and more preferable balance of food hygiene.

Here, the soluble component is the FDA standard No. 177.
It is measured by the maximum elution amount measurement method with n-hexane at 50 ° C. described in Chapter 1520. Specifically, a predetermined amount of a sample sample is kept in n-hexane at 50 ° C. for 2 hours, insoluble components are filtered, and the solvent residue is concentrated to dryness. Can be calculated.

The resin composition for a food packaging film of the present invention and the film thereof are obtained by dry blending or melt blending the components (A) and (B). Various blenders such as a Henschel mixer and a tumbler mixer are used for the dry blend, and various mixers such as a single screw extruder, a twin screw extruder, a Banbury mixer, and a heat roll are used for the melt blend.

In order to produce a film for food packaging using the ethylene / α-olefin copolymer resin composition of the present invention, generally known techniques such as inflation method and T-die method can be used.

The inflation method is also called a blow molding method, in which the resin melt-kneaded by an extruder is extruded into a tube shape through a circular slit of a die, and the pressure of gas (usually air) blown into the tube. A film having a wide range of width can be manufactured by adjusting The ratio of the width of the film to the diameter of the circular slit is called the blow up ratio (BUR). The thickness of the film can be adjusted by selecting the resin extrusion rate and the BUR. The extruded tube is cooled from its outside by gas (usually air) and / or liquid (usually water).

The T-die method is called a cast method, in which the resin melt-kneaded by an extruder is extruded through parallel slits of the die and cooled by being brought into contact with a roll in which a coolant such as water is passed, Generally, a film having good transparency and good thickness accuracy can be produced. The thickness of the film can be adjusted by selecting the resin extrusion rate and the film take-off rate.

The thickness of the single-layer film comprising the ethylene / α-olefin copolymer resin composition of the present invention is preferably 5 to 500 μm, particularly 10 to 100 μm. If the thickness is less than this range, it is difficult to process, and it becomes difficult to exhibit the heat sealing property and hot tack property.

The food packaging film of the present invention is in the form of a composite film with another base material, in order to fully exhibit its excellent low-temperature heat-sealing property and low n-hexane extractability, It is desirable that the ethylene / α-olefin copolymer resin composition film of the invention is present as a surface layer on at least one side.

The substrate can be selected from any polymer capable of forming a film, cellophane, paper, paperboard, woven fabric, aluminum foil and the like. 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, poly-1-butene and poly-4. -Methyl-1-pentene, polyethylene,
Ethylene / vinyl acetate copolymer, ethylene / methacrylic acid ester copolymer, ethylene / acrylic acid ester copolymer, ethylene / methacrylic acid copolymer, ethylene /
Acrylic acid copolymer, polyolefin resin such as ionomer, polyvinylidene chloride, polyvinyl chloride, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc., each gas barrier property, printability, transparency, rigidity, It can be selected according to the purpose of forming the composite film in consideration of adhesiveness and the like. The substrate may be uniaxially or biaxially stretched when the substrate is stretchable, particularly when the properties of the film are improved by stretching such as polyamide resin, polyester resin, polypropylene and the like. When in the form of a composite film, the layer thickness of the food packaging film according to the invention is preferably 1 to 500 μm, in particular 10 to 100 μm. The thickness of the base material layer is arbitrary and can be selected according to the purpose. It is already widely practiced to combine a plurality of base materials with various configurations, and the present invention can also be adopted.

In the present invention, the composite film having two or more layers includes a lamination method such as a dry lamination method, a wet lamination method, a sandwich lamination method and a hot melt lamination method, a coextrusion method, an extrusion coating method, and an extrusion lamination method. It can be produced by known techniques such as (referred to as) and combinations thereof.

In the lamination method, the film of the present invention obtained by the method described in the description of the monolayer film and the above-mentioned substrate are solvent-based adhesive, water-based adhesive,
It is pasted together with a hot melt adhesive, a molten polymer or the like.

In the co-extrusion method, the melted / extruded ethylene / α-olefin copolymer resin composition of the present invention and the other melted / extruded polymer are mixed in the die and / or
Or contact it externally.

In the extrusion coating method, the surface of at least one side of another substrate is coated with the melted / extruded ethylene / α-olefin copolymer resin composition of the present invention. These details are described in "Handbook of Laminating Process" published by the Processing Technology Research Group.

In the composite film thus produced, when the base material is uniaxially or biaxially stretchable, uniaxial or biaxial stretching can be further added. The stretching can be performed by heating the composite film to a temperature range in which the substrate can be stretched by a known method such as a tenter stretching method, an inflation stretching method, a roll stretching method, and if necessary, further heat setting.

Ethylene / α for food packaging films of the present invention
In the olefin copolymer resin composition and the film thereof, in order to further improve the physical properties of the film, 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene- 3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate] methane (IRGANOX 1010) and n-
Octadecyl-3- (4'-hydroxy-3,5'-di-t-butylphenyl) propionate (IRGANO
X 1076) typified by phenolic stabilizers such as bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite and tris (2,4-di-t-butylphenyl) phosphite. Phosphite stabilizers, lubricants represented by higher fatty acid amides and higher fatty acid esters, antistatic agents such as glycerin esters and sorbitan acid esters of fatty acids having 8 to 22 carbon atoms, silica, calcium carbonate, talc, etc. And an antiblocking agent represented by

The food packaging film of the present invention is characterized in that the temperature at which the heat-sealing property is exhibited is low, the temperature range is wide, and the extractability with respect to the hydrocarbon solvent is low, and further the transparency, gloss, and impact are obtained. It has an excellent balance of physical properties such as strength and tear strength, and satisfies all important properties as a film for food packaging. This film is konjac in the form of a single-layer film or a composite film, foods, milk, etc. that are packaged with water such as pickles.
It can be used for packaging various foods such as liquid foods such as sake and soy sauce, dry foods such as confectionery, packaging of processed meats such as ham and sausage.

[0061]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

(I) First, a method for measuring physical properties in the following examples and comparative examples will be described.

(1) Density According to the method specified in JIS K6760. 100
The density was measured after annealing in water at ℃ for 1 hour.

(2) Melt flow rate (MFR) In accordance with the method specified in JIS K6760, temperature 1
It was measured at 90 ° C. and a load of 2.16 kg.

(3) Maximum melting peak temperature For the measurement, a differential scanning calorimeter (DSC) DSC-7 manufactured by Perkin Elmer was used. About 10 mg of a test piece cut out from a sheet with a thickness of about 0.5 mm prepared by hot pressing was put in a sample pan for DSC measurement, and 150 ° C. in DSC.
Was pre-melted for 5 minutes, cooled to 40 ° C. at 1 ° C./minute, held for 5 minutes, and then heated to 150 ° C. at a rate of 10 ° C./minute to obtain a thermogram. When there were multiple melting peaks, the highest value was taken as the highest melting peak temperature.

(4) Number average molecular weight and molecular weight distribution GPC (Gel Permeation Chroma)
measurement is performed by Waters 150C
-Type GPC measuring device is used, and Tohso GMH is used for the column.
6-HT, using o-dichlorobenzene as a solvent, 145
It was measured at ° C. The calibration curve was prepared by a standard method using standard polystyrene manufactured by Tosoh Corporation. The molecular weight distribution was calculated as the ratio of weight average molecular weight / number average molecular weight.

(5) Low-temperature heat-sealing property The ethylene / α-olefin copolymer resin composition of the present invention
Obtained by laminating the film on a substrate such as stretched nylon
Cut the two composite films thus cut into a width of 15 mm, and
Layers composed of a ethylene / α-olefin copolymer resin composition
Put the cats on top of each other and use the heat sealer manufactured by Tester Sangyo Co., Ltd.
Using seal surface pressure 1.0kg / cm ², Sealing time
Heat seal with a seal width of 10 mm under the condition of 1.0 second
It was. Heat the seal bar by changing the temperature of the seal bar by 5 ℃.
Sealed. From now on, width 1 is perpendicular to the sealing surface.
Cut out a 5mm specimen and use a Shopper type tensile tester.
Measure 180 ° peel strength at a speed of 200 mm / min using
did. The low-temperature heat-sealing property is the seal measured under the above conditions.
Temperature when the strength exceeds 2 kg / 15 mm width
Temperature at which the seal seal develops). The lower this temperature, the lower the temperature
It shows that the heat sealability is good.

(6) Low temperature hot tack property Ethylene of two composite films of 15 mm width obtained by laminating the ethylene / α-olefin copolymer resin composition film of the present invention on a substrate such as stretched nylon. α
Layers made of an olefin copolymer resin composition are superposed on each other, and one side is 10 g to 200 g (10
(g unit), and using a heat sealer manufactured by Tester Sangyo Co., Ltd., a sealing surface pressure of 1.3 kg / cm ² ,
Heat sealing was performed with a sealing width of 20 mm under the condition of the sealing time of 0.3 seconds. The load falls at the same time as the end of the sealing, and 0.14 seconds after the end of the sealing, the peeling force is applied to the sealing surface due to the load. By sequentially changing the load and performing the test, the load (W) when the actually peeled length reached just 10 cm was determined. Further, the same test was conducted by changing the seal bar temperature (heat sealing temperature) in the range of 110 to 160 ° C. by 10 ° C. The low temperature hot tack property is indicated by the temperature when the load (W) exceeds 30 g, that is, the hot tack property development temperature (HTT). The lower the HTT, the better the low temperature hot tack property.

(7) n-Hexane Soluble Content The measurement was carried out according to the method described in FDA Standard, Chapter 177, Section 1520. Specifically, resin 2.5 ± 0.00
1 g was placed in a flask, 1000 ml of n-hexane was added, and the flask was placed in a water bath adjusted to 50 ° C. in advance and heated. After the temperature of n-hexane in the flask reached 50 ° C, the mixture was left for exactly 2 hours while stirring with a magnetic stirrer. afterwards,
While the n-hexane was warm, natural filtration was performed using a filter paper. The filtrate was collected in a flask that had been precisely weighed in advance, and the recovered filtrate was weighed. As a result, the recovered filtrate was recovered in 90% or more of the initial charged amount. Next, about half of the solvent filtrate was transferred to a 1-liter beaker, and heated and concentrated using a steam bath. High-purity nitrogen gas was blown into the beaker during the concentration. When the amount of solvent in the beaker had decreased due to evaporation, the remaining solvent filtrate was further added, and finally all the solvent filtrate was transferred. When the concentrate had reached approximately 50 ml, it was transferred to a pre-weighed 100 ml evaporating dish. The beaker was heated with n-hexane to 2
After washing twice, the washing solution was added to the same evaporation dish. The evaporation dish was further concentrated by a steam bath under a stream of high-purity nitrogen, and finally all the solvent was evaporated. The evaporation dish containing the residue was transferred to a vacuum desiccator, left for 12 hours or more, and the net weight of the dried residue was weighed with an accuracy of 0.0001 g. The results were corrected with blank test values corresponding to the non-volatile substances in n-hexane used in the test. From the result of the above method, the n-hexane soluble content was calculated by the following formula. n-Hexane soluble content (% by weight) = ((residual weight g) /
(Sample weight g)) x 100

(II) Preparation of ethylene / α-olefin copolymer resin composition and production of monolayer film

(1) Method 1 The ethylene / α-olefin copolymer pellets of the components (A) and (B) were dry blended at a predetermined mixing ratio to obtain a T-die having a die width of 400 mm and a die lip of 0.7 mm. Using a Tanabe Plastics film forming machine consisting of a 50 mmφ single screw extruder, a film having a thickness of 50 μm was obtained at an extrusion rate of 10 kg / hr, a die set temperature of 240 ° C. and a chill roll temperature of 75 ° C.

(2) Method 2 The ethylene / α-olefin copolymer pellets of the components (A) and (B) are dry blended at a predetermined mixing ratio to obtain a spiral die having a die diameter of 125 mm and a die lip of 2.0 mm, and Using a Placo inflation molding machine K-40R equipped with a one-stage air ring with iris,
Extrusion rate of 24 kg / hr, die set temperature of 170 ° C.,
A 30 μm thick film was obtained with a blow up ratio of 1.8. Furthermore, the surface tension of the film surface is 42 to 45 dyne / c by the corona treatment machine attached to the device.
Corona treatment was performed so as to obtain m.

Manufacture of Composite Film Using a desktop test coater manufactured by Yasui Seiki,
Ren / α-olefin copolymer resin composition single layer film
2 g / m²Urethane adhesive so that
A stretched nylon base film with a thickness of 15 μm
℃, 3kg / cm ²After crimping at 40 ° C for 2 days,
Dry lamination composite film by heating and aging
Got Rum.

Examples 1 to 10 and Comparative Examples 1 to 5 Components (A) and (B) were mixed as shown in Tables 1 to 3,
A film was formed by the above method 1. The density and n-hexane soluble content of the film were measured. Further, this film was attached to a stretched nylon substrate by the dry laminating method by the above-mentioned method, and then the low temperature heat sealing property and the low temperature hot tack property were evaluated.

However, Example 7 was carried out as follows. That is, the components (A) and (B) were mixed as shown in Table 2 and formed into a film by the method 2 described above. The density and n-hexane soluble content of the film were measured. Further, this film was laminated on a stretched nylon substrate by the dry laminating method by the above-mentioned method, and then the heat sealing property and the hot tack property were evaluated.

The results are shown in Tables 4 to 6.

From the results, the following can be seen. All the examples satisfying the conditions of the present invention show satisfactory results in all evaluation items. On the other hand, Comparative Example 1 and Comparative Example 2 lack the component (B), Comparative Example 3 has an excessively high density of the resin composition, and Comparative Example 4 has the highest value obtained by the differential scanning calorimeter of the component (B). The melting peak temperature is too high, and the density of the component (B) in Comparative Example 5 is too low, and the heat seal developing temperature and / or the hot tack developing temperature are both high, which is unsatisfactory.

[0078]

[Table 1] ----------------------- Comparative Example 1 2 3 4 5 (A ) Component type * 1 A1 A1 A1 A2 A3 Amount wt% 80 60 20 70 60 Characteristic density g / cm ³ 0.912 0.912 0.912 0.921 0.902 MFR g / 10 min * 2 2.0 2.0 2.0 1.5 2.0 Maximum peak temperature ℃ * 3 121 121 121 121 114 Number of melting peaks * 4 3 3 3 3 3 (B) Component type * 5 B1 B1 B1 B2 B3 amount wt% 20 40 80 30 40 Characteristic density g / cm ³ 0.902 0.902 0.902 0.895 0.910 MFR g / 10 min * 2 2.0 2.0 2.0 3.0 1.8 Number average molecular weight * 6 96100 96100 96100 88000 98200 Molecular weight distribution * 7 2.0 2.0 2.0 2.0 2.1 Maximum peak temperature ℃ * 3 92 92 92 84 103 Number of melting peaks * 4 1 1 1 1 1 Resin composition (A) + (B) Density g / cm ³ 0.911 0.907 0.905 0.913 0.905 MFR g / 10 min * 2 2.0 2.0 2.0 1.8 1.9 n-Hexane soluble content wt% 2.3 2.5 1.7 4.0 4.9 −−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−

[0079]

[Table 2] ------------------------------------------ Comparative Example 6 7 8 9 10 (A ) Component type * 1 A3 A4 A1 A1 A3 Amount wt% 20 60 60 60 60 Characteristic density g / cm ³ 0.902 0.919 0.912 0.912 0.902 MFR g / 10 min * 2 2.0 1.9 2.0 2.0 2.0 Maximum peak temperature ℃ * 3 114 120 121 121 114 Number of melting peaks * 4 3 3 3 3 3 (B) Component type * 5 B1 B1 B4 B5 B5 amount wt% 80 40 40 40 40 Characteristic density g / cm ³ 0.902 0.902 0.905 0.910 0.910 MFR g / 10 min * 2 2.0 2.0 1.9 2.0 2.0 Number average molecular weight * 6 96100 96100 96900 96300 96300 Molecular weight distribution * 7 2.0 2.0 2.0 1.8 1.8 Maximum peak temperature ° C * 3 92 92 95 102 102 Number of melting peaks * 4 1 1 1 1 1 Resin composition (A) + (B) Density g / cm ³ 0.902 0.912 0.909 0.911 0.904 MFR g / 10 min * 2 2.0 1.9 2.0 2.0 2.0 n-hexane soluble wt% 3.0 1.2 2.8 1.3 3.1 −−−−−−−−− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−

[0080]

[Table 3] ------------------------------------------ Ratio Comparative Example 1 2 3 4 5 (A ) Component type * 1 A1 A3 A5 A1 A3 Amount wt% 100 100 80 70 60 Characteristic density g / cm ³ 0.912 0.902 0.930 0.912 0.902 MFR g / 10 min * 2 2.0 2.0 2.5 2.0 2.0 Maximum peak temperature ℃ * 3 121 114 123 121 114 Number of melting peaks * 4 3 3 1 3 3 (B) Component type * 5--B1 B6 B7 amount wt% 0 0 20 30 40 Characteristic density g / cm ³ 0.902 0.905 0.870 MFR g / 10 min * 2 2.0 2.1 2.5 Number average molecular weight * 6 96100 57600 91700 Molecular weight distribution * 7 2.0 4.1 2.1 Maximum peak temperature ℃ * 3 92 115 56 Number of melting peaks * 4 1 2 1 Resin composition (A) + (B) Density g / cm ³ 0.912 0.902 0.924 0.909 0.889 MFR g / 10 min * 2 2.0 2.0 2.4 2.0 2.2 n-hexane soluble content wt% 4.1 17.0 1.2 4.8> 50 −−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−−−−−−−

[0081]

[Table 4] -------------------------- Seal onset temperature ℃ 110 106 94 109 97 Hot tack onset temperature ℃ 112 110 105 110 103 ------------------------------------------------------------------------------------------------------------------------------------------ −−−−−

[0082]

[Table 5] ------------------ Comparative Example 6 7 8 9 10 Evaluation Heat Seal development temperature ℃ 92 108 94 96 94 Hot tack development temperature ℃ 100 112 105 106 101 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−−

[0083]

[Table 6] ---------------------------- Seal onset temperature ℃ 116 114 119 115 94 Hot tack onset temperature ℃ 122 120 128 120 110 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−−

* 1 Type of component (A) A1 to A5: ethylene-1-hexene copolymers A1 to A5 were all produced by high pressure ionic polymerization using a titanium catalyst. * 2 MFR: Melt flow rate at a temperature of 190 ° C and a load of 2.16 kg * 3 Maximum peak temperature: Maximum melting peak temperature by differential scanning calorimeter * 4 Number of melting peaks: Number of melting peaks by differential scanning calorimeter * 5 ( B) Types of components B1 to B3, B6 and B7: ethylene-1-butene copolymer B4 and B5: ethylene-1-hexene copolymer B1 to B4 and B7 are all solution polymerization using a vanadium catalyst. Manufactured by. B5 was produced by a solution polymerization method using a metallocene catalyst. B6 was produced by high pressure ionic polymerization using a titanium-based catalyst. * 6 Number average molecular weight: Number average molecular weight measured by GPC method * 7 Molecular weight distribution: Molecular weight distribution represented by the ratio of weight average molecular weight / number average molecular weight

[0085]

As described above, according to the present invention, in addition to mechanical strength such as impact strength, tensile strength and tear strength,
It was possible to provide a resin composition for a food packaging film and a food packaging film having the performance required as a food packaging material such as low temperature heat sealability and food hygiene.

Claims (9)

[Claims] 1. A resin composition obtained by uniformly melt-kneading 10 to 95% by weight of the following component (A) and 90 to 5% by weight of the component (B), and having a density of 0.890 to 0.920.
g / cm ³ , a temperature of 190 ° C., a melt flow rate at a load of 2.16 kg of 0.5 to 20 g / 10 minutes, and an n-hexane soluble content of 6% by weight or less, a resin for a food packaging film. Composition. Component (A): made of ethylene and α-olefin having 3 to 12 carbon atoms and having a density of 0.900 to 0.940 g / cm 3.
³ , the temperature was 190 ° C., the melt flow rate at a load of 2.16 kg was 0.5 to 30 g / 10 minutes, and the maximum melting peak temperature measured by a differential scanning calorimeter was more than 110 ° C. Polymer (B) component: made of ethylene and α-olefin having 3 to 12 carbon atoms and having a density of 0.880 to 0.920 g / cm 3.
³ , the temperature is 190 ° C., the melt flow rate at a load of 2.16 kg is 0.5 to 30 g / 10 minutes, and the GPC
Number average molecular weight measured by the method is 35,000 to 15
And the molecular weight distribution represented by the ratio of weight average molecular weight / number average molecular weight is 1.8 to 3.0, and the maximum melting peak temperature measured by a differential scanning calorimeter is 60 to 11
Ethylene / α-olefin copolymer observed in the range of 0 ° C 2. Ethylene / α-obtained by copolymerizing ethylene and α-olefin, wherein the component (A) is present in the presence of a catalyst system containing a titanium compound and an organoaluminum compound.
The composition for a food packaging film according to claim 1, which is an olefin copolymer. 3. The resin composition for a food packaging film according to claim 1, wherein the component (A) is an ethylene / α-olefin copolymer having two or more endothermic peaks measured by a differential scanning calorimeter. 4. The resin composition for a food packaging film according to claim 1, wherein the α-olefin of the component (A) has 6 to 12 carbon atoms. 5. The resin composition for a food packaging film according to claim 1, wherein the component (B) is an ethylene / α-olefin copolymer having only one endothermic peak measured by a differential scanning calorimeter. 6. The component (B) in the presence of a catalyst system containing a metallocene compound and an oxygen-containing organoaluminum compound or a vanadium compound and an organoaluminum compound,
The composition for a food packaging film according to claim 1, which is an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and α-olefin. 7. The component (B) is 1 to 3 in a hydrocarbon solvent.
The composition for a food packaging film according to claim 6, which is an ethylene / α-olefin copolymer obtained by copolymerizing ethylene and α-olefin at a pressure of 0 kg / cm ² . 8. The resin composition for a food packaging film according to claim 1, wherein the α-olefin as the component (B) has 6 to 12 carbon atoms. 9. A food packaging film using the resin composition for a food packaging film according to any one of claims 1 to 8.