TWI704055B - Polyethylene film for packaging and polyethylene film for overlap packaging - Google Patents

Abstract

The present invention provides a polyethylene film for packaging and a polyethylene film for overlap packaging that have low moisture permeability, good printing processability, heat sealability, excellent crease retention, excellent crease retention, and excellent blocking resistance and transparency.

According to the present invention, a base material obtained by uniaxially stretching an unstretched film for packaging of a resin composition containing 100 parts by mass of high-density polyethylene and 25-75 parts by mass of low-density polyethylene to 6-16 times One or both sides of the film are provided with a heat-sealing layer composed of ethylene-(meth)acrylic acid copolymer or neutralized salt with a total thickness of 0.2~5.0μm, which can obtain low moisture permeability, good printing processability, and heat-sealability , Excellent crease retention, polyethylene film for packaging with excellent crease retention, blocking resistance and transparency.

Description

Polyethylene film for packaging and polyethylene film for overlap packaging

The present invention relates to a polyethylene film for packaging in which the content is wrapped, packaged by folding and heat-sealed to seal the package, and a polyethylene film for overlap packaging.

In the overlap package that wraps the contents and then folds the package, heat sealing is often performed to seal the package. Therefore, the packaging film requires heat sealability. In addition, for packaging films, printing processes such as company names, product names, trademark indications, and ingredient descriptions related to the contents are often carried out. However, if the packaging film has high moisture permeability, it is easy to absorb moisture during the printing process. Because of the occurrence of leakage, packaging films with low moisture permeability are desired. In addition, since the contents are wrapped and packaged by folding, there is a demand for a packaging film with excellent crease retention that can retain creases. On the other hand, heat-sealable materials that are adhered by heating sometimes adhere to each other during storage and cause blocking (blocking), which causes problems when the film is exported from the film roll for printing. Therefore, the packaging film Requires blocking resistance. In addition, in order to recognize the contents and cope with back printing, it is sometimes desired that the packaging film has high transparency.

As a packaging film with heat-sealability, Patent Document 1 discloses a heat-sealable cellophane, which uses cellophane as a substrate, and has a polyester-based resin on at least one side of the substrate. Heat seal layer of ingredients. However, cellophane has a high moisture permeability, so there is a problem that it is prone to omission during printing.

Patent Document 2 discloses a heat-sealable polypropylene film using polypropylene as a base material. However, although the polypropylene film has a low moisture permeability and is not easy to miss printing during printing processing, it has the problem of poor crease retention and inability to retain creases.

Patent Document 3 discloses a polyethylene film having a heat-sealing layer and an easily tearable layer. Although polyethylene film has low moisture permeability and good printing processability, it cannot be made of general-purpose materials because the tearable layer requires the use of special terpolymers. In addition, its manufacturing method is also limited to multilayer extrusion using multiple extruders.

Patent Document 4 discloses a laminate including a uniaxially stretched layer and a heat-sealing layer. The uniaxially stretched layer is formed by uniaxially stretching high-density polyethylene and non-linear low-density polyethylene. Forming.

【Existing technical documents】

【Patent Literature】

[Patent Document 1] JP 2001-096670 A

[Patent Document 2] JP 2001-171056 A

[Patent Document 3] JP 2006-56029 A

[Patent Document 4] JP 2008-155527 A

The object of the present invention is to provide a polyethylene film for packaging that has good printing processability due to low moisture permeability, heat sealability, excellent crease retention, and excellent blocking resistance (blocking resistance) and transparency. And polyethylene film for overlapping packaging.

In-depth studies have been conducted to achieve the above-mentioned problems. As a result, it was found that a substrate film obtained by uniaxially stretching a resin composition composed of high-density polyethylene and low-density polyethylene is provided with a specific resin combination on one or both sides. The heat-sealable layer composed of a material can obtain a polyethylene film for packaging that has low moisture permeability, is less likely to cause omission during printing, has excellent crease retention, can retain creases, and has heat sealability.

That is, in order to solve the above-mentioned problems, the present invention adopts the following means.

(1) A polyethylene film for packaging, which is provided with a heat seal layer on one or both sides of a base film, and the base film is a film obtained by uniaxially stretching an unstretched film to 6-16 times. The unstretched film is composed of a resin composition containing 100 parts by mass of high-density polyethylene and 25-75 parts by mass of low-density polyethylene, and the heat-sealing layer is composed of a resin containing ethylene-(meth)acrylic acid copolymer or neutralized salt Composition, the total thickness of the heat seal layer is 0.2 to 5.0 μm.

(2) The polyethylene film for packaging as described in (1) has a haze of less than 15% and a heat seal strength of 0.1N/15mm or more.

(3) A polyethylene film for overlap packaging using the packaging described in (1) or (2) Use polyethylene film.

(4) A method for manufacturing a polyethylene film for packaging, which is the method for manufacturing a polyethylene film for packaging as described in (1) or (2), comprising the following steps: applying a coating liquid containing a resin composition to a base film Then, drying is performed to form the heat-sealing layer.

The polyethylene film for packaging of the present invention has heat-sealability. In addition, it uses polyethylene with low moisture permeability as the main material of the base material, so it has good printing processability. In addition, because of its excellent crease retention, it can maintain creases and is resistant to creases. Both adhesion and transparency are excellent. In addition, the polyethylene film for packaging can be applied to overlap packaging.

1‧‧‧Base film

2‧‧‧Heat Sealing Layer

3‧‧‧Cellophane tape

Fig. 1 is a cross-sectional view showing an example of the polyethylene film for packaging of the present invention. Fig. 1A shows an example in which a heat seal layer 2 is provided on one side of a base film 1, and Fig. 1B shows an example in which a heat seal layer 2 is provided on both sides of the base film 1. There is an example of the heat seal layer 2.

2 is a schematic diagram of a method for evaluating the adhesion between the base material and the heat seal layer. FIG. 2A shows a state before the cellophane tape 3 is peeled off, and FIG. 2B shows a state in which the cellophane tape 3 is peeling off.

Hereinafter, a preferred embodiment for implementing the present invention will be described. It should be stated that the following The illustrated embodiment shows an example of the representative embodiment of the present invention, and should not be used to narrowly interpret the scope of the present invention.

As shown in FIGS. 1A to 1B, the polyethylene film for packaging of the present invention is provided with a heat-sealing layer 2 on one or both sides of the base film 1. FIG. 1A shows an example in which the heat-sealing layer 2 is provided on one side of the base film 1, and FIG. 1B shows an example in which the heat-sealing layer 2 is provided on both sides of the base film 1.

Hereinafter, the base film 1 and the heat-sealing layer 2 will be described in detail.

〈Base film〉

The base film in the present invention is composed of a resin composition containing 100 parts by mass of high-density polyethylene and 25 to 75 parts by mass of low-density polyethylene, more preferably containing 100 parts by mass of high-density polyethylene and 35 to 35 parts by mass of low-density polyethylene. 65 parts by mass of resin composition. If the content of low-density polyethylene is less than 25 parts by mass, the transparency of the film base material decreases. On the other hand, if the content of the low-density polyethylene is more than 75 parts by mass, the crease retention property decreases. The thickness of the film is preferably 5 to 100 μm, and more preferably in the range of 10 to 60 μm. If it is thinner than 5 μm, the strength necessary for a film cannot be obtained, on the other hand, if it is thicker than 100 μm, the crease retention tends to decrease.

(High-density polyethylene)

The high density polyethylene used in the present invention preferably has a density of 0.94~0.97g/cm ³ , a melting point of 126~135°C measured by the DSC method, a temperature of 190°C specified in JISK-6922-2, and a load of 2.16kg The lower melt flow rate is 0.05~10.0g/10 minutes.

(Low-density polyethylene)

The low-density polyethylene used in the present invention preferably has a density of 0.91~0.93g/cm ³ , a melting point of 100~125°C measured by the DSC method, a temperature specified in JISK-6922-2 of 190°C, and a load of 2.16kg The lower melt flow rate is 0.05~10.0g/10 minutes.

If necessary, additives such as heat stabilizers, antioxidants, ultraviolet absorbers, antiblocking agents, lubricants, antistatic agents, pigments, dyes, etc. may be added to the resin composition constituting the base film.

(Mixed raw materials)

The method of mixing the raw materials of the resin composition constituting the base film, that is, high-density polyethylene, low-density polyethylene, and other additives, can be a commonly used known method. For example, a method of mixing at room temperature or a temperature around room temperature using a well-known mixer such as a Henschel mixer, ribbon mixer, Banbury mixer, and drum mixer can be mentioned. After mixing, after kneading and melting using a mixing roll, a single-screw or twin-screw extruder, etc., the obtained sheet or strand can be crushed, cut, etc., and molded into pellets. In the case where the resins have been molded into pellets, the resins may be mixed and used directly.

(Film molding)

Film forming can be performed as follows, for example. The mixed raw material mixture is fed to an extruder, melted, extruded through a film die, and cooled in a molding machine, thereby forming an unstretched film having a thickness in the range of about 20 to 1400 μ. The obtained unstretched film is uniaxially stretched in the longitudinal or transverse directions at 100°C to 140°C, thereby obtaining a stretched film. It should be noted that the stretching ratio is 6 to 16 times, Preferably it is the range of 8-15 times. If the stretching ratio is less than 6 times, the crease retention of the resulting film will deteriorate, and if the stretching ratio exceeds 16 times, stretching will become difficult. As a stretching method, a longitudinal uniaxial stretching method based on roll stretching or a horizontal uniaxial stretching method based on tenter stretching can be used. The horizontal uniaxial stretching method based on tenter stretching is preferable. In addition, the film can be stretched to 1.1 to 3 times in the direction perpendicular to the stretching direction within the range of not losing the crease retention of the film.

(Film post-processing)

In order to stabilize the dimensions of the stretched film, heat treatment (heat setting) at 100 to 165°C for 1 to 60 seconds can shrink it by about 1 to 10% in the stretching direction.

In addition, the substrate film is preferably surface-treated to control its wettability. The wettability index of the base film is preferably 36 to 52 dyne/cm, more preferably 40 to 48 Dyne/cm. If the wettability index is less than 36 Dyne/cm, the printing ink is likely to peel off from the film during printing, and the adhesion to the heat seal layer is also reduced. On the other hand, if the wettability index is greater than 52, after winding the film, poor film development is likely to occur due to blocking. The method of improving the wettability of the surface of the substrate film layer is not particularly limited, and a well-known film surface treatment method can be used, for example, corona treatment, plasma treatment, flame treatment, etc. can be used.

<Heat Sealing Layer>

The heat-sealing layer in the present invention may be provided on one side or both sides of the film base material, but it is more preferable to be provided on one side in terms of productivity and processing operability.

The total thickness of the heat seal layer in the present invention is 0.2 to 5.0 μm, more preferably 0.3 to 4.8 μm. If If the total thickness of the heat-sealing layer is thinner than 0.2 μm, the heat-sealability decreases. On the other hand, if the total thickness of the heat-sealing layer is thicker than 5.0 μm, the blocking resistance is reduced.

The heat-sealing layer in the present invention is composed of a resin composition containing an ethylene-(meth)acrylic acid copolymer or a neutralized salt. By using these compounds, it is possible to form a heat-sealable layer satisfying all of heat-sealability, adhesion to the base film, blocking resistance, and transparency. As the neutralizing salt, for example, sodium salt, potassium salt, calcium salt, magnesium salt, zinc salt, iron salt, copper salt, ammonium salt, alkanolamine salt, etc. can be used. Among them, the sodium salt, ammonium salt, and alkanolamine salt of the ethylene-acrylic acid copolymer can provide a good balance of heat sealability, adhesion to the base film, blocking resistance, and transparency, and are therefore preferred.

If necessary, additives such as heat stabilizers, antioxidants, ultraviolet absorbers, antiblocking agents, lubricants, and antistatic agents may be added to the resin composition constituting the heat seal layer.

(Formation of heat seal layer)

As a method for forming a heat-seal layer on a base film, a conventionally known method may be used. Examples include the following methods: co-extrusion in which the base film is simultaneously extrusion molded; The method of melt-coating the heat-sealable layer; the method of laminating the separately prepared base film and the heat-sealable film; the resin composition constituting the heat-sealable layer is dissolved or emulsified or dispersed in water or solvent to make a coating liquid, The method of applying the coating liquid to a previously prepared base film, etc.

Among them, for the method of applying the coating liquid containing the resin composition constituting the heat-sealing layer to the substrate film, by selecting the concentration of the coating liquid, the coating method, and the coating conditions, the total heat-sealing layer can be The thickness is preferably controlled to a total thickness of 5.0 μm or less that can achieve both heat sealability and blocking resistance.

The coating method of applying the coating liquid to the substrate film layer is not particularly limited, and a known coating method can be used. For example, gravure coating, gravure offset coating, comma coating, bar coating, kiss coating, etc. can be used. By using a temperature-adjustable hot-air drying device to dry the coating liquid applied to the base film layer at a temperature of 60 to 120°C, a heat seal layer can be formed on the base film.

The ethylene-(meth)acrylic acid copolymer or neutralized salt used in the heat-sealing layer of the present invention has excellent dispersibility in water and self-emulsification, so it can be used as an aqueous dispersion (dispersion) or an aqueous emulsion ( (Emulsion) to adjust the coating liquid. At this time, in order to improve the wettability and drying properties to the base film, an organic solvent may be added to the coating liquid as needed.

[Example]

Hereinafter, examples and comparative examples are given in Table 1 to describe the present invention more specifically. These Examples and Comparative Examples are all examples and do not limit the content of the present invention.

【Table 1】

<Example 1>

High-density polyethylene (made by Japan Polyethylene, NovatecHD HY530, density 0.96g/cm ³ , melting point 135°C (DSC method), MFR 0.55g/10 minutes (temperature 190°C specified in JIS K 6922-2, load 2.16kg) )) 100 parts by mass and low-density polyethylene (made by Japan Polyethylene, NovatecLD LF244E, density 0.924g/cm ³ , melting point 112°C (DSC method), MFR 0.6g/10 minutes (temperature 190 specified in JIS K 6922-2) ℃, load 2.16kg)) 60 parts by mass are dry blended in a drum mixer, fed to a single screw extruder for kneading and melting, extruded with a film die, and cooled in a molding machine to a thickness of 290μm The unstretched film was formed, and the unstretched film was stretched by a tenter stretching method at 120°C in the transverse direction at a stretching ratio of 12 times to obtain a film with a thickness of 24 μm. Furthermore, in order to improve the wettability of the film surface, corona treatment (46 dyne/cm) was performed on both sides to obtain a base film.

Coating stock solution A (made by Sumitomo Seiki, Zaikthene AC-HW-10) containing ethylene-acrylic acid copolymer ammonium salt as an aqueous dispersion of the resin composition constituting the heat-sealing layer was diluted with water and methanol to prepare the heat-sealing layer formation The coating liquid is applied to the base film using a gravure coater, and dried using a hot air drying device at 80°C. A heat seal layer with a thickness of 2.0 μm is formed on one side of the base film and then wound into a roll. A polyethylene film for packaging provided with a heat seal layer on one side was obtained.

<Examples 2~5>

Except that the number of addition parts of the low-density polyethylene was changed according to Table 1, in the same manner as in Example 1, a polyethylene film for packaging provided with a heat seal layer was obtained.

<Examples 6-9>

Except changing the draw ratio at the time of base film molding according to Table 1, it carried out similarly to Example 1, and obtained the polyethylene film for packaging provided with a heat seal layer.

<Examples 10~14>

Except that the total thickness of the heat-sealing layer was changed according to Table 1, the same procedure as in Example 1 was carried out to obtain a polyethylene film for packaging provided with a heat-sealing layer.

<Examples 15-17>

Except that the heat-sealing layer was formed on both surfaces, similarly to Example 1, Example 10, and Example 14, a polyethylene film for packaging provided with a heat-sealing layer was obtained.

<Examples 18-20>

According to Table 1, the coating stock solutions B to D in the form of water-based dispersion or water-based emulsion used in the preparation of the coating solution for forming the heat-sealing layer were changed, and in the same manner as in Example 1, a packaging polymer with a heat-sealing layer was obtained. Vinyl film.

B: Sodium salt of ethylene-acrylic acid copolymer (Zaikthene AC-NC manufactured by Sumitomo Seiki)

C: Potassium salt of ethylene-methacrylic acid copolymer (MYE-30ER manufactured by Marufang Chemical)

D: Ethylene-methacrylic acid copolymer (AQUATEX AC-3100 manufactured by Japan Coating Resin)

<Comparative Examples 1~2>

Except that the number of addition parts of the low-density polyethylene was changed according to Table 1, in the same manner as in Example 1, a polyethylene film for packaging provided with a heat seal layer was obtained.

<Comparative Examples 3~4>

Except changing the draw ratio at the time of base film molding according to Table 1, it carried out similarly to Example 1, and obtained the polyethylene film for packaging provided with a heat seal layer.

〈Comparative Examples 5-6〉

Except that the total thickness of the heat-sealing layer was changed according to Table 1, the same procedure as in Example 1 was carried out to obtain a polyethylene film for packaging provided with a heat-sealing layer.

<Comparative Examples 7~9>

According to Table 1, the aqueous dispersion or aqueous emulsion coating stock solutions E to G used in the preparation of the heat-sealing layer forming coating liquid were changed in the same manner as in Example 1 to obtain polyethylene for packaging with a heat-sealing layer film.

E: Acid-modified polyolefin (MGP-055 manufactured by Marufang Chemical)

F: Ethylene-vinyl acetate copolymer (AQUATEX MC-3800 manufactured by Japan Coating Resin)

G: Polymethyl methacrylate (Rikabondo ES-90 manufactured by Japan Coating Resin)

<Comparative Example 10>

Using cellophane (#300) as the base film, heat-sealable cellophane was obtained as follows.

Using the coating stock solution A in the form of an aqueous dispersion of the ethylene-acrylic acid copolymer ammonium salt in the resin composition constituting the heat seal layer, the coating stock solution A was diluted with water and methanol to prepare the coating solution for forming the heat seal layer, and the gravure coater was used The coating solution is applied to the base film, and dried using a hot air drying device at 80°C. A heat seal layer with a thickness of 2.0 μm is formed on one side of the base film and then wound into a roll to obtain a heat seal layer on one side. The heat-sealable cellophane.

The measuring method and evaluation method of characteristics are shown below.

〈Haze (transparency)〉

The so-called haze refers to the ratio of diffuse transmitted light to total transmitted light when visible light is irradiated to the film. Here, in accordance with ASTM D1003, the haze of the polyethylene film for packaging was measured using a haze meter (manufactured by Suga Test), and the following judgment was made (n=5).

◎ (Excellent): Haze (average value) is less than 15%.

○ (good): Haze (average value) is 15% and less than 25%.

× (not possible): The haze (average value) is 25% or more.

<Crease retention>

For crease retention, cut out a 100mm×100mm test piece from the polyethylene film for packaging, fold it in half in the MD (length) direction, press it with a load of 5kg (pressure 10kPa) for 10 seconds, and then place it on TD (width) Fold it in half in the direction, pressurize with a load of 5kg (pressure 20kPa) for 10 seconds, after releasing the pressurization, observe the state change under an environment of 23℃±2 and 50±5% relative humidity, and proceed with Make a decision (n=3).

◎ (Excellent): After 2 days of pressurization, all 3 specimens can maintain a 4-fold state.

○ (Good): After 2 days of pressing, one or two of the three test pieces can maintain a 4-fold state.

X (not possible): After 2 days of pressurization, none of the 3 test pieces could maintain the 4-fold state.

<Adhesion between base film and heat seal layer>

As shown in FIG. 2A, a portion where the heat-seal layer 2 is applied and a portion where the heat-seal layer 2 is not applied are provided on the base film 1, and a polyethylene film is produced in the same manner as in the above-mentioned embodiment. As shown in FIG. 2B, on the finished polyethylene film, a cellophane tape 3 with a width of 18 mm was attached to the portion where the heat seal layer 2 was not coated with the heat seal layer 2. At this time, the uncoated part is only attached with a length of 10 mm, and the coated part is attached with a length of 100 mm. From the attached cellophane tape 3, using a manual crimping roller (width 45mm, diameter 95mm, mass 2kg) covered with a rubber layer of thickness 6mm, reciprocating crimping once at a speed of about 5mm/s. On the side where the heat seal layer 2 is not applied, peel the cellophane tape 3 at an angle of 180° at 23±2°C and a relative humidity of 50±5%, and observe whether the heat seal layer 2 is removed from the packaging polyethylene film Peel off and make the following judgment (n=5).

◎ (Excellent): No heat-sealing layer 2 is peeled from the polyethylene film for packaging.

X (not possible): One or more heat-sealing layers 2 are peeled from the polyethylene film for packaging.

<Heat seal strength>

Cut out two specimens with a width of 15mm and a length of 60mm and overlap them. Use a heat seal tester (manufactured by TESTER SANGYO) to overlap the center of the specimen under the conditions of a pressure of 0.1MPa, a temperature of 120°C, and a time of 0.5 seconds. Part 15mm×20mm is heat sealed. Tensile testing machine (made by Shimadzu Manufacture), fix the unheated parts of the two specimens to each chuck, and pull them in the opposite direction at a speed of 200mm/min at a temperature of 23±2°C and a relative humidity of 50±5% to measure this The peel strength at the time was taken as the heat seal strength (n=5).

◎ (Excellent): Heat seal strength (average value) is 0.3N/15mm width or more.

○ (good): The heat seal strength (average value) is 0.1N/15mm width or more and less than 0.3N/15mm width.

× (unavailable): The heat seal strength (average value) is less than 0.1N/15mm width.

〈Blocking resistance〉

Cut out 2 test pieces (polyethylene film for packaging) according to the size of 60mm in width and 90mm in length and overlap them. Clamp the two test pieces with two smooth thick papers with width 60mm and length 60mm, and place a weight of 3kg. (Pressure 8kPa) and keep in an oven at 40°C. After keeping it for 24 hours, remove the heavy object and let it cool at room temperature for 1 hour or more. After that, the overlapped test piece is peeled off, and the adhesion state at this time and whether the heat seal layer is cracked is observed, and the following judgments are made (n=3).

◎(Excellent): All test pieces have no adhesion.

○ (Good): There is a test piece with slight adhesion, but no test piece with cracks in the heat seal layer.

× (not possible): There are specimens with adhesion and cracks in the heat seal layer.

<Stretchability>

According to the stretching ratio in Table 1, the unstretched base film was stretched by the tenter stretching method to observe whether the breakage occurred, and the following judgment was made (n=10).

◎ (Excellent): In 10 times of processing, none of the breakage occurred.

○ (good): 1 out of 10 times of processing.

× (unavailable): Two or more breaks occurred in 10 machining operations.

<Moisture permeability resistance>

The moisture permeability of the base film was measured in accordance with JIS Z 0208 moisture permeability test method (cup method) condition B of moisture-proof packaging materials, and the following judgment was made (n=2).

◎(Excellent): The moisture permeability (average value) is less than 20g/m ² ‧24hr.

× (not possible): The moisture permeability (average value) is 20g/m ² ‧24hr or more.

<Comprehensive judgment>

In the evaluation of the above-mentioned haze to moisture permeability resistance, the worst evaluation result is regarded as a comprehensive judgment.

In Example 1, excellent results were obtained in all of transparency, crease retention, adhesion between the base film and the heat seal layer, heat seal strength, blocking resistance, and stretch processability.

In Examples 2 to 5, when the low-density polyethylene is 25 parts by mass relative to 100 parts by mass of the high-density polyethylene, the transparency tends to decrease. When the low-density polyethylene is 75 parts by mass relative to 100 parts by mass of the high-density polyethylene, the stretching processability tends to decrease.

In Examples 6 to 9, when the stretch magnification during the formation of the base film was 6 times, the crease retention tended to decrease. When the stretch magnification at the time of forming the base film is 16 times, the stretch processability tends to decrease.

In Examples 10-14, when the total thickness of the heat-sealable layer is 0.2 μm, the heat-sealability tends to decrease. When the total thickness of the heat seal layer is 5.0 μm, the blocking resistance tends to decrease.

In Examples 15-17, even if heat-sealing layers are provided on both sides of the substrate, when the total thickness of the heat-sealing layer is 0.2μm, the heat-sealability tends to decrease, and when the thickness is 5.0μm, the blocking resistance decreases. the trend of.

In Examples 18 to 20, even if the type of ethylene-(meth)acrylic acid copolymer constituting the heat seal layer was changed, the transparency, crease retention, adhesion between the base film and the heat seal layer, heat seal strength, Excellent results were also obtained in blocking resistance and stretch processability.

In Comparative Examples 1 to 2, when the low-density polyethylene is less than 25 parts by mass, the transparency is significantly reduced, and when it is more than 75 parts by mass, the stretch processability is significantly reduced.

In Comparative Examples 3 to 4, when the stretch magnification of the base film is less than 6 times, the crease retention is significantly reduced, and when it is higher than 16 times, the stretch processability is significantly reduced.

In Comparative Examples 5 to 6, when the total thickness of the heat-sealing layer is less than 0.2 μm, the heat-sealing strength is significantly reduced, and when it is greater than 5.0 μm, the blocking resistance is significantly reduced.

In Comparative Examples 7-9, ethylene-(meth)acrylic acid copolymers or neutralized salts other than The transparency, adhesion to the base film, heat-seal strength, and blocking resistance of the coating liquid in the form of an aqueous dispersion composed of other raw materials were not satisfactory.

In Comparative Example 10, the heat-sealable cellophane provided with a heat-sealable layer using cellophane as a base material is to obtain moisture permeability resistance.

1‧‧‧Base film

2‧‧‧Heat Sealing Layer

Claims (4)

A polyethylene film for packaging, which is provided with a heat seal layer on one or both sides of a base film, wherein the base film is a film formed by uniaxially stretching an unstretched film to 6 to 16 times. The unstretched film is composed of a resin composition containing 100 parts by mass of high-density polyethylene and 25-75 parts by mass of low-density polyethylene, and the heat-sealing layer is composed of a resin composition containing ethylene-(meth)acrylic acid copolymer or neutralized salt The total thickness of the heat-sealing layer is 0.2-5.0 μm. The polyethylene film for packaging according to claim 1, wherein the haze is less than 15%, and the heat sealing strength is 0.1N/15mm or more. A polyethylene film for overlap packaging in which the polyethylene film for packaging as described in claim 1 or 2 is used. A method for manufacturing a polyethylene film for packaging, wherein the polyethylene film for packaging is the polyethylene film for packaging according to claim 1 or 2, and the manufacturing method comprises the following steps: coating a coating liquid containing a resin composition After the base film is dried, the heat-sealing layer is formed.

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