JPH07285202A - Laminated resin film - Google Patents

Abstract

PURPOSE:To improve the heat resistance, cutting properties, hand and drape etc., by laminating a film layer consisting of a linear ethylene-alpha-olefin copolymer and a specified glyceride on a crystalline propylene resin film. CONSTITUTION:A laminated resin film is formed by providing a film layer of a linear ethylene-alpha-olefin copolymer with a density of 0.880-0.935g/cm<3> wherein a glyceride of the formula (wherein one of R<1>, R<2> and R<3> is a 2-6C acyl group and another one is an 8-22C acyl group and the remaining one is a H or a 2-22C acyl group) and 0.5-15wt.% anti-fogging agent selected from fatty acid esters being esters of 12-22C higher fatty acid with aliphatic polyhydric alcohol and having at least one alcoholic hydroxyl group are incorporated. There exists no possibility of breakage by melting when a food-contg. porcelin container is wrapped with this film and it is heated in an electric range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food packaging wrap film having excellent adhesiveness, heat resistance, cuttability and texture.

[0002]

2. Description of the Related Art A wrapping film for food packaging is used for wrapping food in ordinary households, restaurants, etc. and storing it in a refrigerator or a freezer, or heating it in a microwave oven (microwave cooker). It is also used to wrap ramen, soba noodles, soup, etc. on tableware with contents.

The food is wrapped here for the purpose of preventing the food from drying (water scattering), preventing dust from entering, and preventing the food from jumping out of the tableware. Such a wrapping film for food packaging has a width of 20 to 45 cm and a paper tube with a width of 20 to 45 cm.
It is wound up to about 100 m and stored in a paper carton box, which is used after being appropriately cut by a saw blade attached to the upper end of the side wall of the box.

The following items are required for this wrap film. Be transparent enough to see through the contents. When pulling back from the carton box by hand, do not tear it into small pieces. Be sticky. It must have heat resistance to the extent that the film does not melt when used in a microwave oven. Good tearability when cut with a saw blade.

At present, a wrap film using a vinylidene chloride resin is mainly used. However, there is a drawback that the wrap film is not cut along the saw blade at the time of cutting and is cut obliquely. As a substitute, the development of ethylene resin is being actively conducted.

However, since the ethylene resin wrap film is easily stretched and is not easily torn, a considerable tensile force is required at the time of cutting, the film cannot be cut well, and the carton box is deformed. In addition, there are problems such as poor heat resistance when used in a microwave oven and low stiffness of the film, making it difficult to handle.Therefore, it cannot be replaced with vinylidene chloride resin and is used only in a part of the market. Not not.

As a film capable of satisfying the cutting property and heat resistance, JP-A-57-96858 and JP-A-57-189850 disclose propylene-ethylene copolymer and propylene-butene-1 copolymer. Although a laminated film of a propylene-ethylene-butene-1 copolymer and polypropylene has been proposed in combination, these laminated films are not tacky and cannot be used as household wrap films.

Further, in JP-A-1-195043, a linear low-density polyethylene (ethylene-α-olefin) is formed on both surfaces of an ethylene-propylene copolymer or an ethylene-propylene-butene-1 copolymer. (Copolymer)
Although a heat-shrinkable film obtained by laminating the above has been proposed, this film has low adhesive strength and is practically difficult to use as a household wrap film that does not require heat shrinkage.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in wrapping films for food packaging, and its object is to have transparency and heat resistance. Another object of the present invention is to provide a wrap film having excellent cuttability and texture and having extremely excellent adhesiveness.

[0010]

The present invention provides a glyceride (a ₁ ) represented by the following formula (I) on one or both sides of a crystalline propylene resin film layer (A).

[0011]

[Chemical 2]

[Wherein R¹, R²And R³One of them is charcoal
An acyl group having a prime number of 2 to 6, and the other one having a carbon number of 8 to 22
And the other one is H or has 2 to 2 carbon atoms.
22 is an acyl group. ] And 12 to 22 carbon atoms
Is an ester of higher fatty acid and aliphatic polyhydric alcohol
A fat having at least one alcoholic hydroxyl group
Fatty acid ester (a ₂) 0.5 to 1 antifogging agent selected from
5 wt% contains a density of 0.880 to 0.935 g / c
m³Of the linear ethylene-α-olefin copolymer of
It also provides a laminated resin film in which a rum layer (B) is laminated.
Of.

Crystalline propylene-based resin layer (A) The crystalline propylene-based resin which imparts heat resistance contains propylene as a main component and ethylene, butene-1,
Hexene-1, octene-1,4-methylpentene-
A binary copolymer with an α-olefin such as 1,3-methylpentene-1 or a ternary copolymer of propylene, ethylene and an α-olefin can be used.

In order to obtain a proper sag flexibility as a wrap film, propylene and an α-olefin having 2 to 8 carbon atoms (excluding propylene) rather than a propylene homopolymer.
And a ternary copolymer composed of propylene, ethylene, and α-olefin are preferable. Among them, 1 to 10% by weight of ethylene, 74 to 96% by weight of propylene, and 3 to 25% by weight of α-olefin having 4 to 8 carbon atoms.
The copolymer with is most suitable.

Preferably, it is a random copolymer having an ethylene content of 1.5 to 8% by weight, a butene-1 content of 8 to 17% by weight, and a propylene content of 75 to 90.5% by weight, and has a melt flow rate (JIS). P-7210; 230 ° C,
2.16 kg load) 1 to 12 g / 10 minutes, Q value (Mw
/ Mn) is 3.5 to 5, and the degree of crystallinity is 20 to 55% (X-ray method), and more preferably 20 to 40% is a propylene-ethylene-butene-1 copolymer.

Such a propylene-based terpolymer is
JP-B-55-6643, JP-A-50-79195,
As can be seen in JP-A-54-162785, it is produced by supplying a mixture of ethylene, propylene and α-olefin to a polymerization system and carrying out random copolymerization using a Ziegler-Natta catalyst. As the α-olefin, butene-1, pentene-1, hexene-
1, Heptene-1, Octene-1, and 4-methylpentene-1 can be used, and these can be used alone or in combination of two or more.

As is well known, the Ziegler-Natta type catalyst is basically composed of a combination of a transition metal compound component and a reducing metal compound component, and is well known including various modifiers thereof. As the transition metal compound component, compounds of transition metals of groups IV to VI of the periodic table can be generally used, and among them, titanium compounds are preferable.

Examples of the titanium compound include halides, oxyhalides, alkoxy compounds, and alkoxyhalides. Specific compounds include titanium halogen compounds such as titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium trichloride, titanium tribromide, titanium triiodide, titanium dichloride, etc. Used by preference. These can also be mixed and used.

A compound having a valence of less than the highest valence can be prepared by reducing the highest valence compound with hydrogen, a metal, an organometallic compound, a metal hydride, etc., depending on the reducing agent and / or the reducing method. Depending on the case, decomposition or modification compounds of reducing agents may coexist.
Such can also be used. In particular,
For example, T obtained by reducing metallic aluminum of titanium tetrachloride
There is iCl ₃ · 1 / 3AlCl ₃ .

Suitable reducing metal compound components are hydrides of metals of groups I to III of the Periodic Table and organometallic compounds. Particularly suitable compounds are aluminum hydrides and organoaluminum compounds of general formula (II) below.

[0021]

Embedded image AlR _n X _3-n (II)

Here, R is a hydrocarbon residue, especially 8 carbon atoms.
Less than or equal to alkyl, cycloalkyl, aryl groups, X
Is halogen and n is an integer of 1 to 3. Chlorine is suitable as the halogen, at least for economic reasons. Specific examples of such an aluminum compound include trialkylaluminum (alkyl = methyl to octyl),
Examples include dialkylaluminum chloride, alkylaluminum sesquichloride, alkylaluminum dichloride. These can also be mixed and used.

The amount ratio of the transition metal compound component and the reducing metal compound component may be any that can be generally adopted in a Ziegler type catalyst. Specifically, for example, in the case of a combination of the titanium compound A and the organic aluminum compound B, the B / A molar ratio is about 0.5 to 20, preferably 1 to 10. It is known that the Ziegler type catalyst basically consisting of the above two components can be modified by various modifying agents.

One example of such a modifier is an electron donating compound. As the electron-donating compound, an acid anhydride,
Examples include esters, ketones, amines, glycols and glycol ethers. Specifically, it is, for example, methyl methacrylate. In carrying out the copolymerization, an inert organic solvent such as benzene, toluene, xylene, pentane,
Hexane, heptane, hydrocarbons such as cyclohexane, or in the presence or absence of halogenated hydrocarbons such as chlorobenzene and methylene chloride, or using a monomer for polymerization such as the α-olefin as a solvent, or in a gas phase. Arbitrary temperature, for example, temperature of about 0 to 200 ° C. (preferably 30 to 100 ° C.), and arbitrary pressure such as normal pressure to 100
It may be carried out at a pressure of about atmospheric pressure (preferably atmospheric pressure to 60 atmospheric pressure) with or without a molecular weight regulator such as hydrogen.

Such crystalline propylene-based resin is available from Mitsubishi Yuka Co., Ltd. as Mitsubishi Polypro "SPX4400""SPX".
It is sold under the trade name of 4400G "and under the trade name of Sumitomo Noprene" FL6316 "by Sumitomo Chemical Co., Ltd. If the propylene-based constitutional unit of this propylene-based three-element copolymer is less than 74% by weight, The resulting copolymer becomes rubber-like and becomes difficult to mold, and the transparency of the film is impaired, while if it exceeds 96% by weight, the rigidity of the film is increased and the flexibility is impaired.

If the content of ethylene is less than 1% by weight, slurry polymerization of the propylene-based terpolymer is difficult. If it exceeds 10% by weight, the crystallinity of the terpolymer will be lowered, the film formability will be difficult, and the transparency of the film will be impaired. Further, if the content of the α-olefin structural unit in the propylene-based terpolymer is less than 3% by weight, the rigidity of the film is too high and the feeling is impaired. On the other hand, if it exceeds 25% by weight, the transparency of the film is impaired.

The crystalline propylene-based resin of the layer (A) is an ethylene-vinyl acetate copolymer (vinyl acetate content is 5 to 25% by weight) and ethylene-acrylic acid (acryl) within a range not impairing the transparency of the film. Acid content is 5 to 2
0% by weight) copolymer, ethylene-methyl acrylate copolymer (methyl acrylate content 5-20% by weight), ethylene-methyl methacrylate copolymer, density 0.890
~ 0.910 g / cm ³ , melt index 0.1
-10g / 10min low density polyethylene, density 0.8
86 to 0.920 g / cm ³ linear low-density polyethylene, metal salt of copolymer consisting of α-olefin and acrylic acid, methacrylic acid, maleic acid (Zn, Na, K,
Li, Mg, etc.), ethylene-propylene copolymer rubber,
An ethylene-butene-1 copolymer elastomer or the like may be added in an amount of 40% by weight or less for the purpose of improving the flexibility of the laminated resin film.

Linear ethylene-α-olefin copolymer
The resin composition layer (B) is laminated on one side or both sides of the (A) layer to easily exhibit flexibility and tackiness, and the density is 0.880 to 0.935 g / c.
The linear ethylene-α-olefin copolymer of m ³ is mainly composed of ethylene, butene, butene-1, and hexene-.
It is a copolymer of α-olefin such as 1,4-methylpentene-1 and octene-1 with 1 to 2 kinds of 3 to 20% by weight of α-olefin.

Preferably, the α-olefin content is 5 to 1
Melt flow rate (JIS K-676 at 5% by weight)
It is preferable that 0) is 0.5 to 5 g / 10 minutes from the viewpoint of feeling and tackiness. The linear ethylene-α-olefin copolymer has a glyceride (a ₁ ) represented by the following formula (I) for imparting tackiness, antifogging property and flexibility to the laminated resin film.

[0030]

[Chemical 4]

[Wherein R¹, R²And R³One of them is charcoal
An acyl group having a prime number of 2 to 6, and the other one having a carbon number of 8 to 22
And the other one is H or has 2 to 2 carbon atoms.
22 is an acyl group. ] And 12 to 22 carbon atoms
Is an ester of higher fatty acid and aliphatic polyhydric alcohol
A fat having at least one alcoholic hydroxyl group
Fatty acid ester (a ₂) 0.5 to 1 antifogging agent selected from
5 wt% is included.

Examples of the glyceride (a ₁ ) represented by the above formula (I) include, for example, diacetyl monooleyl glycerin, diacetyl monolauryl glycerin, diacetyl monopalmityl glycerin, monoacetyl dioleyl glycerin, monoacetyl dilauryl glycerin, Monoacetyl monopalmityl glycerin, monoacetyl monooleyl glycerin, monoacetyl monolauryl glycerin, monoacetyl monocapryl glycerin, monoacetyl brushyl glycerin, monopropyl monobrassil glycerin, monoacetyl monoerucyl glycerin, dipropionyl monolauryl glycerin Etc. are available.

Among these, those in which ^{two of} R ¹ , R ² and R ³ are acyl groups having 2 to 4 carbon atoms and the other one is an acyl group having 8 to 22 carbon atoms are more preferable. The fatty acid ester (a ₂ ) is an ester compound of a polyhydric alcohol such as glycerin, sorbitol, pentaerythritol, propylene glycol, polyethylene glycol and polypropylene glycol, and a higher fatty acid such as oleic acid, linoleic acid and lauric acid. Specifically,
Monoglycerin oleate, polyglycerin oleate, polyglycerin stearate, polyglycerin polyricinoleate, glycerin mono, di-ricinoleate, glycerin acetyl ricinoleate, glycerin diacetomonolaurate, propylene glycol oleate, propylene glycol laurate, penta Erythritol oleate, polyethylene glycol oleate, polypropylene glycol oleate, sorbitan oleate, sorbitan laurate, polyethylene glycol sorbitan oleate, polyethylene glycol sorbitan laurate and the like can be used. Among them, polyglycerin polyricinolate, polyglycerin oleate, glycerin diacetomonolaurate and sorbitan oleate are preferable.

When the content of these antifogging agents is less than 0.5% by weight, sufficient flexibility and tackiness cannot be obtained, while when it exceeds 15% by weight, a large amount of bleeding deteriorates the appearance of the laminated resin film. . It is preferably 3 to 12% by weight.
Further, the above antifogging agent was added to the layer (A) in the same manner as the layer (B).
You may mix | blend 5-15 weight%.

Laminated Resin Film In the laminated resin film of the present invention, the thickness of the (A) layer is 1 to 1.
0 μm, preferably 2 to 5 μm, the thickness of the (B) layer is 2 to
A laminated film having a thickness of 20 μm, preferably 2 to 6 μm and a total thickness of 7 to 30 μm, preferably 8 to 22 μm, and a degree of haze (JIS-Z-6714) of 5% or less, preferably 3% or less. , Elmendorf tear strength (J
IS-Z-1702) is 0.5 to 30k both vertically and horizontally
It is preferably g / cm.

If the thickness of the crystalline propylene resin film layer (A) of the laminated resin film is less than 1 μm, the heat resistance will be insufficient. If the thickness exceeds 10 μm, the rigidity increases and the flexibility,
The texture is damaged. The method for producing this laminated resin film is not particularly limited, but it is preferably produced by the following method. The resins constituting the layers (A) and (B) are melted and kneaded using a plurality of extruders and supplied to one coextrusion die, and the multilayer film is coextruded from the coextrusion die and the laminated film is cooled. After solidification, the multilayer film is reheated to a temperature range in which it can be stretched, then stretched in the machine direction and the transverse direction by at least 3 times or more, then annealed, and then cooled. The stretching method may be a method utilizing the peripheral speed difference of the rolls, a mandrel method, a tenter method, or an inflation method.

[0037]

EXAMPLES Next, the present invention will be specifically described with reference to Examples and Comparative Examples. These do not limit the invention in any way.

Example 1 Propylene-ethylene random copolymer resin [propylene content 95.8% by weight, ethylene content 4.2% by weight,
Density 0.89 g / cm ³ , MFR 8 g / 10 min, melting point 1
40 ° C., crystallinity 35%; Mitsubishi Yuka Co., Ltd., trade name “Mitsubishi Polypro FX4”], caliber 65 mm, L / D2
It was kneaded at 250 ° C. using the extruder of No. 5 and led to the resin path of the intermediate layer of the three-layer T die.

On the other hand, a linear ethylene-butene-1 copolymer [ethylene content 93.0% by weight, butene-1 content 7.
0% by weight, MFR 2g / 10 minutes, density 0.911g / c
m ³ ; manufactured by Mitsubishi Petrochemical Co., Ltd., trade name “Mitsubishi Polyethylene LL
UF240 "] 95% by weight and diglycerin oleate (manufactured by Riken Vitamin Co., Ltd., trade name" Rikemar O71 "
D "] 5% by weight of the resin composition (B) having a caliber of 50
mm, kneaded at 230 ° C. using an L / D24 extruder,
The three-layer T-die is supplied to the resin paths forming the upper and lower surface layers and laminated in the T-die, and the thickness ratio of the intermediate layer is 6, and the upper and lower surface layers have a composition ratio of 2, respectively. After extrusion to form a three-layer film, this is heated to 95 ° C and the take-up direction (longitudinal direction) is used by utilizing the difference in peripheral speed of the rolls.
After being stretched 3 times, it was heated again to 95 ° C., stretched 6 times in the transverse direction using a tenter, and annealed at 100 ° C. to obtain a laminated stretched film having a thickness of 10 μm. Table 2 shows the physical properties of this laminated stretched film.

Comparative Example 1 Table 2 shows the physical properties of a commercially available vinylidene chloride resin wrap film manufactured by K Company.

Comparative Example 2 Low density polyethylene resin [density 0.93 g / cm ³ , M
FR 3 g / 10 minutes, melting point 113 ° C .; manufactured by Mitsubishi Petrochemical Co., Ltd.
Product name "Mitsubishi Poly-LD ZH-51"] 98.5
Wt% and glycerin monooleate [RIKEN VITAMIN CO., LTD.
Made, product name "Rikemar OL-100"] 1.5% by weight
The resin composition consisting of the above is kneaded at 180 ° C. using an extruder having a diameter of 65 mm and L / D25, extruded with a T die so that the total thickness of the film is 13 μm, cooled with a cooling roll, and slit into a width of 300 mm. A single layer film was obtained.

Examples 2 to 6 and Comparative Examples 3 to 4 The resin for the intermediate layer and surface layer having the composition shown in Table 1 was used.
A laminated resin film was obtained by carrying out film molding in the same manner as in Example 1 except that the extrusion temperature was set under the conditions shown in the same table and the thickness constitution and the draw ratio were set as shown in Table 2.
Table 2 shows these physical properties. The abbreviations of the components in Table 1 and the evaluation methods in Table 2 are as follows.

Crystalline propylene-based resin Propylene / ethylene random copolymer FX4; [Physical properties are described in Example 1; trade name of Mitsubishi Yuka Co., Ltd.] Propylene / ethylene / butene-1 random copolymer SPX 4400; [Propylene content 88.7% by weight,
Ethylene content 2.4 wt%, butene-1 content 9.3 wt%, density 0.89 g / cm ³ , MFR 5 g / 10 min, Q
Value 4.5, crystallinity 35%; trade name of Mitsubishi Petrochemical Co., Ltd.] SPX 4400G; [Propylene content 85.8% by weight, ethylene content 1.7% by weight, butene-1 content 12.
5% by weight, density 0.89 g / cm ³ , MFR 5 g / 10
Min, Q value 4.8, crystallinity 30%; trade name of Mitsubishi Petrochemical Co., Ltd.] Propylene homopolymer FL-6CK; [Density 0.90 g / cm ³ , MFR 2.
3 g / 10 minutes, Q value 4.5, crystallinity 60%, trade name manufactured by Mitsubishi Petrochemical Co., Ltd.]

Linear ethylene-α-olefin copolymer UF240; [Physical properties described in Example 1; Mitsubishi Yuka Co., Ltd.
Product name] Ultzex 1030F; [Ethylene content 88.2% by weight, 4-methylpentene-1 content 11.8% by weight, M
FR 2.3 g / 10 minutes, density 0.918 g / cm ³ ; manufactured by Mitsui Petrochemical Co., Ltd.]

Antifog agent Riquemal O-71-D; [ Diglycerin oleate ;
Riken Vitamin Co., Ltd. product name] Rikemar PL-004; [Glycerin diacetomonolaurate; Riken Vitamin Co., Ltd. product name] Rikemar OL-100; [Glycerin monooleate; Riken Vitamin Co., Ltd. product name]

Evaluation method Degree of haze JIS-Z-6714 Tear strength JIS-Z-1702 Tear elastic modulus ISO-R-1184 Adhesive force Films are overlapped in an area of 1 cm in width and 2 cm in length, and a load of 20 kg is applied to this overlapped portion. The sample for 2 minutes, then pull the sample at a pulling speed of 500 mm /
Maximum load when peeled off in minutes.

Heat resistance 10 g at the lower end of a strip film having a width of 5 cm and a length of 20 cm
The film is hung in a constant temperature atmosphere for 1 hour under a load of, and the temperature until the film is cut is measured. (The higher it is, the more it can withstand long-time heating by a microwave oven.) Adhesiveness The adhesiveness to the pottery when the pottery dish is wrapped with a film. ○: Good ×: Peeling off

Texture The presence / absence of stickiness and the rigidity of the film when touched with a hand are evaluated by feeling. ◯: No stickiness and good flexibility. △ ^* : Sticky. △ ^** : Low waist strength. Cutability The cutability of the film with the saw blade attached to the wrap film box. ◯: Good Δ: Slightly bad ×: Poor microwave oven characteristics A ceramic dish containing 100 cc of corn soup was wrapped with a film and heated in a microwave oven for 4 minutes. ○: No change ×: Damaged

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

EFFECTS OF THE INVENTION The product of the present invention is a laminated resin film having excellent transparency, heat resistance, cuttability, texture, and extremely excellent adhesiveness, and a ceramic container containing food with this laminated resin film. Even if it is lapped and heated in a microwave oven, there is no phenomenon such as melt fracture, and it is sufficiently durable for use in a microwave oven.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C08L 23/08 KEQ

Claims (3)

[Claims] 1. A crystalline propylene resin film layer
On one or both sides of (A), linear ethylene-α-ole
Fin copolymer, glyceride represented by the following formula (I) (a
₁) [Chemical 1][In the formula, R¹, R²And R³One of them has 2 to 6 carbon atoms
Acyl group, and the other one is an acyl group having 8 to 22 carbon atoms.
And the other one is H or acyl having 2 to 22 carbon atoms.
It is a base. ] And a higher fatty acid having 12 to 22 carbon atoms
And an ester of aliphatic polyhydric alcohol,
And fatty acid ester having one alcoholic hydroxyl group
(A ₂0.5 to 15% by weight of an antifogging agent selected from
Density is 0.880 to 0.935 g / cm³Straight chain
Film layer of ethylene-α-olefin copolymer (B)
A laminated resin film having a structure in which are laminated. 2. The antifog agent added to the linear ethylene-α-olefin copolymer of the layer (B) is selected from polyglycerin polyricinolate, polyglycerin oleate, glycerin diacetomonolaurate and sorbitan oleate. The laminated resin film according to claim 1, which is selected alone or as a mixture of two or more kinds. 3. The crystalline propylene-based resin of layer (A) comprises:
A copolymer of ethylene, propylene and an α-olefin having 4 to 8 carbon atoms, wherein the amount of each component is 1 to 10% by weight of ethylene, 74 to 96% by weight of propylene and 4 to 8 carbon atoms. α-olefin is 3 to 25% by weight,
Its crystallinity is 20-55%, MFR is 1-12g / 1
The laminated resin film according to claim 1, which is a crystalline propylene-based resin having a Q value of 3.5 to 5 at 0 minutes.