JP3223350B2 - Wrapping film for packaging and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a wrapping film for packaging and a method for producing the same. More specifically, the present invention relates to a packaging wrapping film comprising at least three multilayer films or at least five multilayer films, and a method for producing the same.

[0002]

2. Description of the Related Art Wrapping films for packaging are widely used for sealing foods. For business use, for example, fruits and vegetables, fresh fish, meat, prepared foods, and the like are placed in a plastic tray, which is effective in preventing dust adhesion during transportation and display. In restaurants and ordinary households, it is effective in preventing drying when stored in a refrigerator or heating in a microwave oven, etc., has an effect on flavor retention such as flavor, prevention of odor diffusion, and prevention of odor adhesion to other foods. Its usage is increasing. In particular,
In general households and convenience stores, microwave ovens have spread due to recent changes in food culture, and are used to control water evaporation during microwave processing such as cooking or heating cooked foods, thawing frozen foods, and reheating cold foods. It is used exclusively and its applications are expanding.

[0003] In many cases, these packaging wrapping films are generally used by storing a film having a width of 20 to 45 cm and a thickness of 10 to 25 µm wound on a core material such as a paper tube in a paper box case. The necessary amount of film is appropriately cut with a saw blade-like cutter attached to this case, the food storage container or the food itself is wrapped with this film, and the container opening and the food are sealed with the appropriate adhesiveness of the film. It is.

[0004] However, the cuttability of easily cutting a film is one of the important required characteristics. Further, container adhesion (moderate adhesiveness and flexibility) to various containers such as glass containers, ceramics, plastic containers compatible with microwave ovens, and paper containers is also an important characteristic. Furthermore, even with heating by a microwave oven, it is necessary to have heat resistance that can withstand no change in appearance such as perforation, whitening phenomenon, fusing, etc., and of course, mechanical strength characteristics against various stresses during lapping are also important. Required characteristics.

As described below, packaging films for such uses are easily tearable when used in a required amount, and have mechanical strength characteristics that can withstand the stress during wrapping, and appropriate adhesion to various containers (adhesiveness, Flexibility), heat resistance that does not cause changes in appearance such as heat melting, shrinkage, whitening, etc. by microwave heating, food hygiene, does not contain harmful substances such as plasticizers, stabilizers, antioxidants, etc., environmental hygiene, When incinerated as waste, it is required that harmful substances such as chlorine are not released into the atmosphere.

Heretofore, as these wrapping films for packaging, single-layer films using resins such as polyvinylidene chloride, polyethylene and polyvinyl chloride have been known. The mainstream polyvinylidene chloride is generally a biaxially stretched film with excellent cutability, moderate flexibility, tackiness,
(Container adhesion), so that it has good so-called wrapping characteristics, and further has heat resistance due to resin characteristics, and is suitably used in practical use. However, it has a disadvantage that it is expensive and inferior in economy. Furthermore, when polyvinylidene chloride is incinerated as waste, hydrochloric acid gas is generated, and the problem of air pollution at the level of the global environment has become apparent. Further, since polyvinylidene chloride uses a large amount of a plasticizer for the purpose of imparting adhesive properties, it has been pointed out that there is a problem of food harm, such as a problem of transfer to food. Problems similar to the above-mentioned polyvinylidene chloride have been pointed out for polyvinyl chloride.

On the other hand, polyethylene is widely used because it is inexpensive and economical, and has no problem of environmental pollution due to incineration. However, it has a drawback in heat resistance derived from resin materials, and especially in the microwave oven as in this application. The aptitude is insufficient for response. As described above, it is difficult to say that all of the conventional food packaging films are sufficient.

There is a demand for a suitable film instead of the vinylidene chloride resin film and the vinyl chloride resin film, and various wrapping single-layer films mainly composed of an olefin resin have been proposed. There is a limit to satisfying all of the above required qualities simultaneously.

[0009] On the other hand, many wrapping films for packaging have been proposed in which the limitation of the single-layer structure is solved by a multilayer laminated structure. For example, JP-A-8-309938 discloses a three-layer structure in which a specific propylene-based resin is added with a specific amount of a dissolvable crystal nucleating agent, and an ethylene-α-olefin copolymer is laminated on both sides of the intermediate layer. Film, JP-A-6-31882
JP, JP-A-6-87197, JP-A-6-87
No. 198 and the like, the present inventors have proposed a film formed by laminating a layer made of a specific ethylene-α-olefin copolymer on at least one surface of a propylene-α-olefin copolymer layer. . Further, Japanese Patent Application Laid-Open No. 7-1
In Japanese Patent No. 25157, the present inventors have proposed a three-layer film in which an ethylene-based resin layer is laminated on both sides of a propylene-based resin layer whose melting point is specified and stretched.
Japanese Patent Application Laid-Open No. 7-148898 discloses that a layer made of a polypropylene resin composition is provided on an intermediate layer, and both surfaces thereof are made of a resin composition containing ultra-low-density polyethylene having a density of 0.91 g / cm ³ or less and low-density polyethylene. A film formed by laminating layers, JP-A-9-1749 discloses a layer comprising a polyethylene-based resin composition containing an ester of an aliphatic polyhydric alcohol and a fatty acid on both surfaces with a propylene-based resin layer as an intermediate layer. Have been proposed.

However, all of the properties required for wrapping films for packaging, namely, easy tearing properties, mechanical strength properties to withstand stress during wrapping, and appropriate adhesion to various containers (adhesiveness, flexibility) ), It has not been possible to simultaneously satisfy all of the heat resistance and the like that can cope with microwave heating.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide excellent tearability, mechanical strength characteristics, adhesion to containers (adhesion, flexibility), microwave oven suitability, etc., as well as food hygiene and environmental hygiene. It is another object of the present invention to provide a wrapping film for packaging which has no problem and is economically advantageous and a method for producing the same.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, have specified a resin composition having required characteristics required for each layer and devised an arrangement of the structure. As a result, it has been found that the object of the present invention is achieved, and the present invention has been completed.

That is, the present invention provides at least three layers (A layer / B layer / C layer) comprising the following outer layers (A and C layers) of (i) and an intermediate layer (B layer) of (ii) below. Wrapping for packaging, characterized in that said multilayer film comprises 5 to 30% of the thickness of said intermediate layer (layer B) with respect to the total thickness of said multilayer film. Film. (I) Both outer layers (A and C layers) are obtained by a high pressure radical polymerization method and have a density of 0.920 to 0.935 g / cm.
³ , the melt flow rate is 2 to 10 g / 10 min and n-
At least one ethylene resin 99 to 60 selected from an ethylene homopolymer, an ethylene-vinyl ester copolymer, and an ethylene-unsaturated carboxylic acid ester copolymer having a hexane extraction amount of 0.6% by weight or more. % By weight, the content of the repeating unit derived from ethylene is 45 to 6
0 to 10% by weight of ethylene-propylene copolymer
(Ii) an intermediate layer (layer B) having a melting point of 150 ° C. or more,
A layer made of a propylene-based resin having a melt flow rate of 2 to 20 g / 10 minutes

The present invention also relates to the following two outer layers (A and C layers) of (i), an intermediate layer (B layer) of (ii) and an adjacent layer of the intermediate layer (B layer) of (iii) below. Layer (D layer, E layer)
At least 5 layers (A layer / D layer / B layer /
(E layer / C layer), wherein the ratio of the thickness of the intermediate layer (B layer) to the total thickness of the multilayer film is 5 to 30%. Wrapping film for packaging. (I) Both outer layers (A and C layers) are obtained by a high-pressure radical polymerization method and have a density of 0.920 to 0.935 g / c.
m ³ , melt flow rate 2-10 g / 10 min and n
A hexane extraction amount of at least 0.6% by weight of at least one ethylene resin 99- selected from ethylene homopolymers, ethylene-vinyl ester copolymers and ethylene-unsaturated carboxylic acid ester copolymers; 60% by weight,
When the content of the repeating unit derived from ethylene is 45 to 45;
60% by weight of ethylene-propylene copolymer 1-1
A layer composed of a resin composition containing 0% by weight and 0 to 30% by weight of a recycled resin; (ii) the intermediate layer (layer B) has a melting point of 150 ° C. or more, and has a melt flow rate of 2 to 20 g / 10 min. A layer made of a certain propylene-based resin (iii) (D layer, E layer) obtained by a high-pressure radical polymerization method, having a density of 0.920 to 0.935 g / cm ³ ;
An ethylene homopolymer, an ethylene-vinyl ester copolymer, and an ethylene copolymer having a melt flow rate of 2 to 10 g / 10 minutes and an n-hexane extraction amount of 0.6% by weight or more.
100 to 60% by weight of at least one ethylene resin selected from unsaturated carboxylic acid ester copolymers, and the content of repeating units derived from ethylene is 45 to 6
0 to 10% by weight of ethylene-propylene copolymer
Layer comprising a resin composition containing 0% by weight and 0 to 30% by weight of a recycled resin

Further, the present invention is a method for producing a packaging wrapping film, wherein the packaging wrapping film is formed by a co-extrusion method. Hereinafter, the present invention will be described in detail.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The self-adhesive packaging film of the present invention is a film having at least three layers (A layer / B layer / C layer). Both outer layers (A layer, C layer) are layers that do not contain harmful substances such as plasticizers from the viewpoint of food hygiene and have adhesiveness (adhesion, flexibility) to various containers,
0.92 density obtained by high pressure radical polymerization
0 to 0.935 g / cm ³ , melt flow rate (MF
R) is 2 to 10 g / 10 min, and the amount of n-hexane extracted is 0.1.
6% by weight or more of 99 to 60% by weight of at least one ethylene resin selected from ethylene homopolymer, ethylene-vinyl ester copolymer and ethylene-unsaturated carboxylic acid ester copolymer, derived from ethylene Composition containing 1 to 10% by weight of an ethylene-propylene copolymer having a content of a repeating unit (hereinafter referred to as "ethylene unit") of 45 to 60% by weight and a regenerated resin of 0 to 30% by weight It is a layer consisting of The intermediate layer (layer B) has a melting point of 150 ° C. or more and an MFR of 2 to 2 in consideration of easy tearability, microwave oven suitability, and mechanical strength characteristics.
This is a layer made of a propylene-based resin at 20 g / 10 min. Furthermore, in order to effectively exhibit the characteristics of each layer, the ratio of the thickness of the intermediate layer (B layer) to the total thickness of the multilayer film is 5 to 30%, preferably 12 to 20%.

The above-mentioned ethylene resin is a resin obtained by a high-pressure radical polymerization method.
It is at least one resin selected from ethylene-vinyl ester copolymers and ethylene-unsaturated carboxylic acid ester copolymers. The density of the ethylene resin is 0.
If it is less than 920 g / cm ³ , the heat resistance is insufficient.
If it exceeds 35 g / cm ³ , the tackiness is insufficient, which is not preferable. The density is measured by a method specified in JIS K6760. The MFR of the ethylene resin
Is less than 2 g / 10 minutes, it becomes difficult to process the film, while if it exceeds 10 g / 10 minutes, processing stability is affected, which is not preferable. MFR is measured by a method specified in JIS K6760. In addition, the reason why the extraction amount of the n-hexane of the ethylene-based resin was specified to be 0.6% by weight or more was that the low-molecular-weight material contained moderately,
This is because the flexibility is improved. The amount of n-hexane extracted is
It is a measure of the content of a low molecular weight substance in the ethylene resin, and the amount is obtained by forming the ethylene resin into a film and extracting it with n-hexane at 45 ° C for 5 hours as an index. When the amount of n-hexane extracted is less than 0.6% by weight, the effects of tackiness and flexibility derived from the effects of low molecular weight substances cannot be obtained. The upper limit of the amount of n-hexane extracted is 5% by weight. n-
If the amount of hexane extraction exceeds 5% by weight, the tack tends to be too large.

Examples of the vinyl ester of the ethylene-vinyl ester copolymer include vinyl acetate, vinyl propionate, and vinyl neoate. Of these, vinyl acetate is preferred. Further, as the unsaturated carboxylic acid ester of the ethylene-unsaturated carboxylic acid ester copolymer, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl methacrylate, Examples thereof include ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. Of these, methyl methacrylate is preferred.

The ethylene-propylene copolymer used in the present invention is intended to impart tackiness in addition to the tackiness exhibited by the ethylene-based resin, and the content of ethylene units is 45 to 60% by weight. Copolymers can be suitably used. Those having an ethylene unit content of less than 45% by weight or more than 60% by weight are not preferred because the desired tackiness is hardly exhibited. In addition, since the copolymer has no unsaturated bond in the main chain of the polymer, it has excellent weather resistance and heat aging resistance, and has practically superior properties such as long-term storage stability.

As the recycled resin used in the present invention, a trimming loss generated mainly in the step of producing the film of the present invention is used. That is, examples of the recycled resin include an ethylene-based resin and a propylene-based resin. There is no particular limitation on the method for regenerating the trimming loss, and the regenerated resin is used after being finely divided or pelletized by a known method.

The intermediate layer (layer B) of the present invention has a melting point of 150.
° C or more, preferably 155 to 165 ° C, MFR is 2-2.
There is no limitation as long as the propylene resin is 0 g / 10 min, preferably 8 to 14 g / 10 min. Not only propylene homopolymer but also propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene- Ethylene-
Butene-1 copolymer and the like can be used. When the melting point is lower than 150 ° C., heat resistance is insufficient, which is not preferable. The melting point is measured using a differential scanning calorimeter (DSC). If the MFR is less than 2 g / 10 minutes, film processing becomes difficult, and if it exceeds 20 g / 10 minutes, processing stability is affected, which is not preferable. MFR is JIS K6
It is measured by the method specified in 758.

The present invention has a multilayer structure of at least three layers. As described above, the reason is that a resin composition having required characteristics required for each layer is arranged in order to simultaneously satisfy many problems. In addition, a remarkable effect can be obtained by devising the arrangement of the layer structure. The intermediate layer (B layer) in the present invention accounts for 5 to 30%, preferably 12 to 20% of the total thickness of the film. If the thickness of the intermediate layer (layer B) is less than 5%, heat resistance, rigidity, and mechanical strength are insufficient, which is not preferable. On the other hand, if it exceeds 30%, it is not preferable because the easy tearing property (cutting suitability) decreases.

The outer layers (A and C layers) of the present invention contain 99 to 60% by weight, preferably 96 to 78% by weight of the ethylene resin.
% By weight of the ethylene-propylene copolymer is 1 to 10% by weight.
% By weight, preferably 2 to 6% by weight, and
It comprises a resin composition containing up to 30% by weight, preferably 2 to 16% by weight. If the ethylene-based resin is used in an amount of less than 60% by weight, the transparency of the film becomes insufficient. If the ethylene-propylene copolymer is used in an amount exceeding 10% by weight, the tackiness is remarkably increased, and excessive blocking occurs in a film forming process and a product, which is not preferable. If the ethylene-based resin is used in excess of 99% by weight or the ethylene-propylene copolymer is used in less than 1% by weight, the adhesiveness of the film becomes insufficient, which is not preferable. The reclaimed resin always contains an ethylene-based resin and a propylene-based resin, but since both are incompatible with each other, the layer containing them becomes non-uniform. It is not preferable because it becomes cloudy and remarkably lowers the transparency, furthermore, lowers the lapping characteristics and deteriorates the appearance when heated in a microwave oven.

The present invention also relates to the present invention, wherein both outer layers (A and C layers), an intermediate layer (B layer) and both adjacent layers (D layer,
E layer) and at least 5 layers (A layer / D layer /
(B layer / E layer / C layer), wherein the ratio of the thickness of the intermediate layer (B layer) to the total thickness of the multilayer film is 5 to 30%, preferably 12 to 20%. And a packaging wrapping film composed of a multilayer film.

As the outer layers (A and C layers) and the intermediate layer (B layer), the same resin composition and resin as those used for the above-mentioned multilayer film composed of at least three layers can be used. Both adjacent layers (D layer,
E layer) obtained by a high-pressure radical polymerization method, having a density of 0.920 to 0.935 g / cm ³ , a melt flow rate of 2 to 10 g / 10 min, and an n-hexane extraction amount of 0.6% by weight or more. , Ethylene homopolymer, ethylene-
Ethylene-propylene having 100 to 60% by weight of at least one ethylene resin selected from a vinyl ester copolymer and an ethylene-unsaturated carboxylic acid ester copolymer, and having an ethylene unit content of 45 to 60% by weight. This is a layer composed of a resin composition containing 0 to 10% by weight of a copolymer and 0 to 30% by weight of a recycled resin.

The above-mentioned ethylene resin is a resin obtained by a high-pressure radical polymerization method, and is an ethylene homopolymer,
It is at least one resin selected from ethylene-vinyl ester copolymers and ethylene-unsaturated carboxylic acid ester copolymers. The density of the ethylene resin is 0.
If it is less than 920 g / cm ³ , the heat resistance is insufficient.
If it exceeds 35 g / cm ³ , the tackiness is insufficient, which is not preferable. The density is measured by a method specified in JIS K6760. The MFR of the ethylene resin
Is less than 2 g / 10 minutes, it becomes difficult to process the film, while if it exceeds 10 g / 10 minutes, processing stability is affected, which is not preferable. MFR is measured by a method specified in JIS K6760. Further, the reason why the extraction amount of the n-hexane of the ethylene-based resin was specified to be 0.6% by weight or more was that the low-molecular weight material contained moderately, and thus the tackiness,
This is because the flexibility is improved. The amount of n-hexane extracted is
It is a measure of the content of low molecular weight substances in the ethylene-based resin, and the index is based on the amount obtained by forming the ethylene-based resin into a film and extracting it with n-hexane at 45 ° C for 5 hours. If the amount of n-hexane extracted is less than 0.6% by weight, the effects of tackiness and flexibility derived from the effects of low molecular weight substances cannot be obtained. The upper limit of the amount of n-hexane extracted is 5% by weight. n-
If the amount of hexane extraction exceeds 5% by weight, the adhesion tends to be too large.

The vinyl ester of the ethylene-vinyl ester copolymer includes, for example, vinyl acetate, vinyl propionate, vinyl neoate and the like. Among these, vinyl acetate is preferred. Further, as the unsaturated carboxylic acid ester of the ethylene-unsaturated carboxylic acid ester copolymer, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, methyl methacrylate, Examples thereof include ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. Of these, methyl methacrylate is preferred.

The ethylene-propylene copolymer used in the present invention imparts an additional adhesiveness in addition to the adhesiveness exhibited by the ethylene-based resin, and has an ethylene unit content of 45 to 60% by weight. Copolymers can be suitably used. Those having an ethylene unit content of less than 45% by weight or more than 60% by weight are not preferred because the desired tackiness is hardly exhibited. In addition, since the copolymer has no unsaturated bond in the main chain of the polymer, it has excellent weather resistance and heat aging resistance, and has practically superior properties such as long-term storage stability.

As the recycled resin used in the present invention, the trimming loss generated mainly in the step of producing the film of the present invention is used as in the above-mentioned case. That is, examples of the recycled resin include an ethylene-based resin and a propylene-based resin. There is no particular limitation on the method for regenerating the trimming loss, and the regenerated resin is used after being finely divided or pelletized by a known method.

Both adjacent layers (D layer, E layer) of the intermediate layer (B layer)
Layer) is 100 to 60% by weight, preferably 96 to 78% by weight of the ethylene resin, 0 to 10% by weight, preferably 2 to 6% by weight of the ethylene-propylene copolymer, and 0 to 10% by weight of the regenerated resin. -30% by weight, preferably 2-16
It consists of a resin composition containing by weight. If the ethylene-based resin is used in an amount of less than 60% by weight, the transparency of the film becomes insufficient. If the ethylene-propylene copolymer is used in an amount exceeding 10% by weight, the tackiness is remarkably increased, and excessive blocking occurs in a film forming process and a product, which is not preferable. If the above-mentioned regenerated resin is used in an amount exceeding 30% by weight, the layer becomes cloudy and the transparency is remarkably reduced, which is not preferable.

As a method for producing the film of the present invention, a co-extrusion method may be mentioned. As the co-extrusion method, any known method such as a co-extrusion T-die method and a co-extrusion inflation method is used, but a method using a co-extrusion T-die apparatus of three types and five layers is preferable. As the co-extrusion T-die, any of a generally used multi-manifold type and a feed block type may be used.

The thickness of the wrapping film for packaging of the present invention is preferably 6 to 50 μm, more preferably 8 to 15 μm.
μm.

[0033]

As described above in detail, according to the present invention, the present invention has both easy tearing property and mechanical strength capable of withstanding the stress during lapping, and further has appropriate adhesiveness to various containers, heat resistance and electronic resistance. It has excellent practicality such as range suitability, does not contain additives such as plasticizers, antioxidants, and stabilizers that are not desirable for food hygiene, and does not release harmful substances into the atmosphere when incinerated as waste. Can provide a wrapping film for packaging in consideration of the global environment. Also,
The present invention can provide a wrapping film suitable for food packaging. Further, the present invention can provide a method for producing the above wrapping film for packaging.

[0034]

Hereinafter, the present invention will be described in detail with reference to Examples.
The present invention is not limited to these examples.

First, the method for evaluating characteristic values according to the present invention will be described below. (1) Density The density of the ethylene-based resin was in accordance with the method specified in JIS K6760. After annealing for 1 hour in water at 100 ° C., the density was measured. (2) Melt flow rate (MFR) The MFR of the ethylene-based resin was measured by a method specified in JIS K6760. MFR of propylene resin
Was measured by the method specified in JIS K6758. (3) Melting point The melting point of the propylene-based resin was measured using DSC-7 manufactured by Perkin Elmer. A sample having a weight of about 10 mg cut out from a sheet having a thickness of about 0.5 mm produced by a hot press was placed in a sample pan for DSC measurement, and the temperature was raised to 230 ° C., and then lowered to 150 ° C. 4 per minute
After the temperature was lowered to 0 ° C. and held for 5 minutes, 180 ° C. at 5 ° C./minute
The temperature was raised to ° C. to obtain a thermogram. The main peak temperature in the thermogram at the time of this temperature rise was defined as the melting point.

(4) Content of Ethylene Unit in Copolymer Determined from a material balance. Further, using an infrared spectrophotometer, 7
32cm ^-1, and quantified from the characteristic absorption of 720 cm ^-1, confirmed the results of the mass balance. The measurement with an infrared spectrophotometer was performed by quantifying a calibration curve based on a quantitative value obtained by radiation measurement of an ethylene copolymer labeled with ¹⁴ C. (5) Extraction amount of n-hexane Ethylene resin was inflated to a thickness of 30
It was molded into a film of μm to make a sample.
Was extracted for 5 hours in 1 liter of n-hexane at 45 ° C. for 5 hours. (6) Easy tearing property (cut suitability) Wrap the required amount of evaluation film around a commercially available wrap film, store it in a commercially available carton box ("One Wrap" manufactured by Jujo Special Paper Machinery Co., Ltd.), and judge cut suitability by sensitivity evaluation. did. ◎ ・ ・ ・ It cuts along the blade just by pulling lightly. Δ: Cutable, but the film is difficult to stretch. X: The film stretched and could not be cut.

(7) Tensile strength A strip-shaped film specimen having a width of 1.5 cm and a length of 10 cm is gripped and pulled at an interval of 5 cm at a pulling speed of 50 mm / min, and the force required for breaking (unit: g / 1.5 cm) is obtained. It was measured. (8) Elongation at Break The elongation (unit:%) of the film up to the break at the time of measuring the tensile strength was measured. (9) Adhesiveness A 10 cm wide, 15 cm long film specimen was pressure-bonded to a glass plate with a 2 kg rubber roll, and the vertical length was 300 m.
The force required for peeling at a speed of m / min was measured and defined as the adhesive force (g / 10 cm).

(10) Lapping characteristics The qualitative evaluation of the adhesion to the glass cup was made from a practical viewpoint. ◎ ・ ・ ・ Adheres closely. Δ: Insufficient adhesion or peeled off immediately after adhesion. ×: The film does not adhere, or the film has excessive adhesion and is difficult to handle. (11) Heat resistance According to Tokyo Metropolitan Ordinance No. 1027 “Quality display of wrap film” (a 2.5-cm top and bottom of a 3 cm wide, 14 cm long strip-shaped film specimen, a load of 10 g is applied to the lower part,
The maximum temperature at which the film does not break when left in a heated atmosphere for 1 hour in this state is indicated in units of 10 ° C. (12) Suitability for microwave oven A commercially available retort curry was placed in a heat-resistant glass container, wrapped, heated in a microwave oven for 180 seconds, and the change in appearance of the film was evaluated. A: No change occurs in the film. Δ: The film is sticky. X: A hole is formed in the film.

Example 1 As the intermediate layer (B), the melting point was 161 ° C., and the MFR was 12 g / 1.
0-minute polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Noblen WF949C), and both outer layers (A, C)
Polyethylene with an extraction amount of n-hexane of 0.8% by weight, a density of 0.931 g / cm ³ and an MFR of 5 g / 10 min (manufactured by Sumitomo Chemical Co., Ltd .: manufactured by high-pressure radical polymerization, trade name: Sumikasen CE3506) 80% by weight,
Using a resin composition obtained by mixing 4% by weight of an ethylene-propylene copolymer having an ethylene unit content of 52% by weight and 16% by weight of a recycled resin obtained by pelletizing the three-layer film, using a co-extrusion T-die facility. Two types and three layers were laminated by a melt extruder. The total thickness of the obtained three-layer film is 12 μm, and the thickness ratio of the entire structure is A layer: B layer: C layer = 40%: 20
%: 40%. Table 1 shows the properties of the obtained film.

Example 2 The thickness ratio of all the structures was A layer: B layer: C layer = 44%: 12%:
Except having set it to 44%, it carried out similarly to Example 1, and obtained the three-layer film. Table 1 shows the properties of the obtained film.

COMPARATIVE EXAMPLE 1 The thickness ratio of all the structures was A layer: B layer: C layer = 34%: 32%:
Except having set it as 34%, it carried out similarly to Example 1, and obtained the three-layer film. Table 1 shows the properties of the obtained film.

Comparative Example 2 The thickness ratio of all the structures was A layer: B layer: C layer = 48%: 4%: 4
A three-layer film was obtained in the same manner as in Example 1 except that the content was changed to 8%. Table 1 shows the properties of the obtained film.

Comparative Example 3 Example 1 was repeated except that an ethylene-propylene copolymer having an ethylene unit content of 65% by weight was used as the ethylene-propylene copolymer used for both outer layers (A, C). A three-layer film was obtained in the same manner as described above. Table 1 shows the properties of the obtained film.

Comparative Example 4 Example 1 was repeated except that an ethylene-propylene copolymer having an ethylene unit content of 35% by weight was used as the ethylene-propylene copolymer used for both outer layers (A, C). A three-layer film was obtained in the same manner as described above. Table 1 shows the properties of the obtained film.

Comparative Example 5 The resin composition of the outermost layers (A, C) was mixed except that the mixing ratio of polyethylene, ethylene-propylene copolymer resin and self-regenerating resin was 60: 20: 20% by weight. In the same manner as in Example 1, a three-layer film was obtained. Table 1 shows the properties of the obtained film.

[0046]

Table 1-------------------------------------------------------------------------------------Example −−−−−−−−−−−−−−−−−−−−−−−−−−−−− Suitability for cutting ◎ ◎ △ ◎ ◎ ◎ ◎ Tensile strength g / 1.5cm 586 557 787 372 612 632 632 600 Elongation at break% 483 512 389 549 453 468 477 Adhesive g / 10cm 6.8 7.0 6.3 7.3 3.4 3.0 9.8 Lapping characteristics ◎ ◎ △ ◎ × × × Heat resistance ℃ 150 150 150 130 150 150 150 Suitable for microwave oven ◎ ◎ ◎ × ◎ ◎ ◎ △ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Example 3 The intermediate layer (B) had a melting point of 161 ° C. and an MFR of 12 g.
/ 10 min polypropylene (manufactured by Sumitomo Chemical Co., Ltd .: trade name Noblen WF949C), and its both layers (D,
E) Polyethylene having an n-hexane extraction amount of 0.8% by weight, a density of 0.931 g / cm ³ and an MFR of 5 g / 10 minutes (manufactured by Sumitomo Chemical Co., Ltd .: manufactured by high pressure radical polymerization method, trade name) Sumikacene CE3506) A resin composition obtained by mixing 80% by weight, 4% by weight of an ethylene-propylene copolymer having an ethylene unit content of 52% by weight, and 16% by weight of a recycled resin obtained by pelletizing the five-layer film is used. ,
Further, as the outermost layers (A, C), the extraction amount of n-hexane was 0.8% by weight, the density was 0.931 g / cm ³ , and the MFR5
g / 10 min polyethylene (manufactured by Sumitomo Chemical Co., Ltd .: manufactured by high pressure radical polymerization method, trade name: Sumikasen CE350)
6) 97% by weight and the content of ethylene units is 52% by weight
Using a resin composition mixed with 3% by weight of an ethylene-propylene copolymer of the above, three types and five layers were laminated using a co-extrusion T-die facility. The total thickness of the obtained five-layer film is 12 μm,
The thickness ratio of all the structures is A layer: D layer: B layer: E layer: C layer =
20%: 20%: 20%: 20%: 20%. Table 2 shows the properties of the obtained film.

Example 4 The thickness ratio of all the structures was A layer: D layer: B layer: E layer: C layer = 24
A five-layer film was obtained in the same manner as in Example 3, except that the ratio was changed to%: 20%: 12%: 20%: 24%. Table 2 shows the properties of the obtained film.

Comparative Example 6 The thickness ratio of all the structures was A layer: D layer: B layer: E layer: C layer = 13
A five-layer film was obtained in the same manner as in Example 3, except that%: 12%: 50%: 12%: 13%. Table 2 shows the properties of the obtained film.

Comparative Example 7 The thickness ratio of all the structures was A layer: D layer: B layer: E layer: C layer = 24
A five-layer film was obtained in the same manner as in Example 3 except that%: 24%: 4%: 24%: 24%. Table 2 shows the properties of the obtained film.

Comparative Example 8 The procedure of Example 3 was repeated except that the ethylene-propylene copolymer used for both outer layers (A, C) had a content of 65% of ethylene units. A layer film was obtained. Table 2 shows the properties of the obtained film.

Comparative Example 9 The procedure of Example 3 was repeated except that the ethylene-propylene copolymer used for both outer layers (A, C) had a 35% ethylene unit content. A layer film was obtained. Table 2 shows the properties of the obtained film.

Comparative Example 10 The procedure of Example 3 was repeated except that a resin composition containing 80% by weight of an ethylene-based resin and 20% by weight of an ethylene-propylene copolymer was used in both outer layers (A, C). A layer film was obtained. Table 2 shows the properties of the obtained film.

Comparative Example 11 A five-layer film was obtained in the same manner as in Example 3 except that 35% by weight of a recycled resin (obtained by pelletizing a five-layer film) to be mixed into both inner layers (D, E) was mixed. Was. Table 2 shows the properties of the obtained film.

[0055]

Table 2--------------------------------------------------------------------------------------Example 11 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Suitability for cutting ◎ ◎ △ △ ◎ ◎ ◎ ◎ Tensile strength g / 1.5 cm 612 578 773 372 602 622 610 586 Elongation at break% 432 502 403 541 423 398 457 412 Adhesion g / 10cm 6.3 6.3 5.3 6.3 3.8 3.2 9.8 6.3 Lapping properties ◎ ◎ △ △ × × × × Heat resistance ℃ 150 150 150 130 150 150 150 150 Suitable for microwave oven ◎ ◎ ◎ × × × △ △ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koichi Yanase 5-1, Anesaki Beach, Ichihara City, Chiba Prefecture Within Sumitomo Chemical Industries Co., Ltd. (72) Inventor Nobuhiro Hato 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Nippon Paper Industries Inside the Product Development Laboratory Co., Ltd. (72) Inventor Koichiro Hiroshige 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Nihon Paper Industries Inside the Product Development Laboratory (72) Inventor Hajime Tani 11-11, Tanifunawaramachi, Ichifuna-cho, Shinjuku-ku, Tokyo Jujo Within Central Corporation (56) References JP-A-9-239927 (JP, A) JP-A-8-224842 (JP, A) JP-A-7-125157 (JP, A) JP-A-63-262242 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (4)

(57) [Claims] An at least three layers comprising an outer layer (A and C layers) of the following (i) and an intermediate layer (B layer) of the following (ii):
A multilayer film having a layer (layer A / layer B / layer C), wherein the ratio of the thickness of the intermediate layer (layer B) to the total thickness of the multilayer film is 5 to 30%. A wrapping film for packaging, comprising: (I) Both outer layers (A and C layers) are obtained by a high pressure radical polymerization method and have a density of 0.920 to 0.935 g / cm.
³ , the melt flow rate is 2 to 10 g / 10 min and n-
At least one ethylene resin 99 to 60 selected from an ethylene homopolymer, an ethylene-vinyl ester copolymer, and an ethylene-unsaturated carboxylic acid ester copolymer having a hexane extraction amount of 0.6% by weight or more. % By weight, the content of the repeating unit derived from ethylene is 45 to 6
0 to 10% by weight of ethylene-propylene copolymer
(Ii) an intermediate layer (layer B) having a melting point of 150 ° C. or more,
A layer made of a propylene-based resin having a melt flow rate of 2 to 20 g / 10 minutes 2. Both outer layers (A and C layers) of the following (i), an intermediate layer (B layer) of the following (ii), and both adjacent layers (D layer) of the intermediate layer (B layer) of the following (iii) , E layer) comprising at least 5 layers (A layer / D layer / B layer / E layer / C layer), wherein the thickness of the intermediate layer (B 5) to 30% of the thickness of the layer)
% Wrapping film comprising a multi-layer film. (I) Both outer layers (A and C layers) are obtained by a high-pressure radical polymerization method and have a density of 0.920 to 0.935 g / c.
m ³ , melt flow rate 2-10 g / 10 min and n
A hexane extraction amount of at least 0.6% by weight of at least one ethylene resin 99- selected from ethylene homopolymers, ethylene-vinyl ester copolymers and ethylene-unsaturated carboxylic acid ester copolymers; 60% by weight,
When the content of the repeating unit derived from ethylene is 45 to 45;
60% by weight of ethylene-propylene copolymer 1-1
A layer composed of a resin composition containing 0% by weight and 0 to 30% by weight of a recycled resin; (ii) the intermediate layer (layer B) has a melting point of 150 ° C. or more, and has a melt flow rate of 2 to 20 g / 10 min. A layer made of a certain propylene-based resin (iii) (D layer, E layer) obtained by a high-pressure radical polymerization method, having a density of 0.920 to 0.935 g / cm ³ ;
An ethylene homopolymer, an ethylene-vinyl ester copolymer and an ethylene-melt having a melt flow rate of 2 to 10 g / 10 min and an extraction amount of n-hexane of 0.6% by weight or more.
100 to 60% by weight of at least one ethylene resin selected from unsaturated carboxylic acid ester copolymers, and the content of repeating units derived from ethylene is 45 to 6
0 to 10% by weight of ethylene-propylene copolymer
Layer comprising a resin composition containing 0% to 30% by weight of recycled resin 3. The packaging wrapping film according to claim 1, wherein the ratio of the thickness of the intermediate layer (layer B) to the total thickness of the multilayer film is 12 to 20%. 4. A method for producing a packaging wrapping film, wherein the packaging wrapping film according to claim 1 is formed by a co-extrusion method.