CN116761719A - Laminated films and packaging bags - Google Patents

Abstract

The present invention provides a laminated film and a packaging bag. The laminated film (1) includes a base material layer (2) and a sealant layer (4) as the outermost surface on one side of the laminated film (1). The base material layer (2) contains 77-99 parts by mass of high-density polyethylene (A) and 1-23 parts by mass of ultra-high molecular weight polyethylene (B), totaling 100 parts by mass. The high-density polyethylene (A) The density of the ultra-high molecular weight polyethylene (B) is 0.942~0.970g/cm ³ , the melt mass flow rate is 0.1~3.0g/10min under the conditions of a temperature of 190°C and a load of 2.16kg. The density of the ultra-high molecular weight polyethylene (B) is 0.930～0.960g/cm ³ .

Description

Laminated films and packaging bags

Technical field

The invention relates to a laminated film and a packaging bag.

This application claims priority based on Japanese Patent Application No. 2021-7964 filed in Japan on January 21, 2021, and Japanese Patent Application No. 2021-191262 filed in Japan on November 25, 2021, the contents of which are incorporated herein by reference.

Background technique

Conventional packaging bags are made by laminating a base material layer such as polyethylene terephthalate (PET) or polyamide (PA), which has higher heat resistance than the sealant, on the outside of a sealant such as polyethylene (PE). Laminated film. However, since the sealant and the resin of the base material layer are of different types, recyclability is poor.

Patent Document 1 describes an agricultural polyolefin-based multilayer film in which at least one of the outer layer and the inner layer contains ultra-high molecular weight polyethylene with a weight average molecular weight of 400,000 or more. It has been suggested that the multilayer film improves abrasion resistance, imparts breaking strength and tear strength to the film, and can be used as a covering material for gardening facilities such as agricultural greenhouses and agricultural sheds, and the like.

Patent Document 2 describes a stretched polyolefin produced by rolling and stretching a sheet composed of a polyolefin-based resin with a weight average molecular weight of 100,000 to 500,000 and an ultra-high molecular weight polyolefin-based resin with a weight average molecular weight of 1,000,000 or more. Olefin resin sheet. It has been suggested that this resin sheet has excellent tensile strength, tensile rigidity, impact resistance, etc., and is suitable for use as a protective member to protect the human body from impact in sports competitions.

existing technical documents

patent documents

Patent Document 1: Japanese Patent Application Publication No. 2019-98534;

Patent Document 2: Japanese Patent Application Publication No. 2010-167640.

Contents of the invention

technical problem

In the technology of Patent Document 1, from the viewpoint of film transparency and processability, it is preferable that a layer containing ultra-high molecular weight polyethylene and a layer not containing ultra-high molecular weight polyethylene contain low-density polyethylene and/or Ethylene-vinyl acetate copolymer. In Patent Document 1, the proportion of high-density polyethylene in the layer containing ultra-high molecular weight polyethylene is only 56% by mass at the maximum (Example 3). In addition, Patent Document 1 describes using a layer containing ultra-high molecular weight polyethylene as an outer layer, but does not describe using an inner layer not containing ultra-high molecular weight polyethylene as a sealant to form a packaging bag, nor does it describe Any inspiration.

In Example 1 of Patent Document 2, it is described that 70 parts by mass of a high-density polyethylene resin with a weight average molecular weight (Mw) of 330,000, a melting point of 133° C., a density of 0.956, and a melt index (MI) of 0.37 g/10 min. After 30 parts by mass of ultra-high molecular weight polyethylene resin with a weight average molecular weight (Mw) of 2 million to 6 million, a melting point of 141°C, a density of 0.928, and an average particle diameter of 150 μm are melt-extruded and stretched to form an stretched sheet with a thickness of 0.65 mm. , a linear low-density polyethylene film is laminated between stretched sheets to form a laminated film. However, there is no description of arranging the linear low-density polyethylene film of the laminated film on the outermost surface of one side to form a packaging bag, and no suggestion is given.

An object of the present invention is to provide a laminated film and a packaging bag having a base material layer of polyethylene resin that are excellent in heat deformation resistance, impact resistance, and embrittlement resistance.

Technical solutions

The laminated film of the present invention includes a base material layer and a sealant layer as the outermost surface of one side of the laminated film. The base material layer contains 77 to 99 parts by mass of high-density polyethylene (A) and 1 to 23 parts by mass of Ultra-high molecular weight polyethylene (B), 100 parts by mass in total, the density of the high-density polyethylene (A) is 0.942 to 0.970g/cm ³ , and the melt mass is at a temperature of 190°C and a load of 2.16kg The flow rate is 0.1-3.0g/10min, and the density of the ultra-high molecular weight polyethylene (B) is 0.930-0.960g/cm ³ .

The ultra-high molecular weight polyethylene (B) of the base material layer may have an average particle diameter of 5 to 200 μm and a weight average molecular weight of 500,000 or more.

The base material layer may contain the masking agent (C) in a proportion of 5 parts by mass or less.

The masking agent (C) may be titanium oxide.

The sealant layer may be a layer composed of polyethylene resin.

You may have a layer made of polyethylene resin on the opposite side of the base material layer from the sealant layer.

The base material layer may be formed of a resin composition obtained by melting and kneading the high-density polyethylene (A) and the ultra-high molecular weight polyethylene (B).

The base material layer can be formed into a film shape by extrusion molding.

Moreover, the packaging bag of this invention is formed using the said laminated film.

Technical effect

According to the present invention, in a laminated film and a packaging bag having a base material layer of polyethylene resin, the thermal deformation resistance, impact resistance, and embrittlement resistance can be improved.

Description of the drawings

FIG. 1 is an enlarged cross-sectional view showing one embodiment of the laminated film of the present invention.

FIG. 2 is an enlarged cross-sectional view showing another embodiment of the laminated film of the present invention.

Fig. 3 is a front view showing one embodiment of the packaging bag of the present invention.

Symbol Description

1 laminated film

2 base material layer

4 layers of sealant

6 outer layer

10 stand-up bags (packaging bags)

12 Container body

14 spout parts

16 Main body membrane

18 bottom film

20 Heat sealing department

Detailed ways

Hereinafter, the present invention will be described based on preferred embodiments.

As shown in FIG. 1 , the laminated film 1 of this embodiment includes a base material layer 2 and a sealant layer 4 which is the outermost surface of the laminated film 1 side. The base material layer 2 and the sealant layer 4 are preferably formed of polyethylene resin. This can improve recyclability.

In the laminated film 1 of the embodiment, the base layer 2 contains high-density polyethylene (A) and ultra-high molecular weight polyethylene (B).

High-density polyethylene (A) is a polyethylene resin with a density of 942g/cm ^or more. The density of the high-density polyethylene (A) is preferably in the range of 0.942 to 0.970 g/cm ³ , and more preferably in the range of 0.945 to 0.960 g/cm ³ .

The melt mass flow rate (MFR) of the high-density polyethylene (A) is preferably in the range of 0.1 to 3.0g/10min, and more preferably in the range of 0.3 to 1.5g/10min under the conditions of a temperature of 190°C and a load of 2.16kg. within the range. The melt mass flow rate represents the mass of plastic discharged from the mold within 10 minutes (g/10min) when molten plastic is extruded from the mold under specified conditions. The measurement method is specified in JISK7210-1 "Measurement method of melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics".

By setting the density and MFR of the high-density polyethylene (A) within these ranges, the base film forming the base layer 2 has excellent processability, and the heat deformation resistance, impact resistance, and resistance of the laminated film 1 can be improved. Brittleness.

For a total of 100 parts by mass of high-density polyethylene (A) and ultra-high molecular weight polyethylene (B), the blending ratio of high-density polyethylene (A) is preferably in the range of 77 to 99 parts by mass, and may be 81 to 99 parts by mass. parts by mass, more preferably 88 to 97 parts by mass. Accordingly, even if the materials other than high-density polyethylene (A) in the base layer 2 are powder-shaped substances such as ultra-high molecular weight polyethylene (B) or masking agent (C), the processing of the base film can be improved. sex.

The high-density polyethylene (A) contained in the base material layer 2 may be one type or two or more types. In the case where two or more types of high-density polyethylene (A) are used, the density, melt mass flow rate (MFR), etc. may be different within the above range. The blending ratio of the high-density polyethylene (A) may be such that the total of two or more high-density polyethylenes (A) is within the above range.

Ultra-high molecular weight polyethylene (B) is a polyethylene resin that has a higher molecular weight, lower melt viscosity, and worse fluidity in the molten state than ordinary polyethylene. The density of ultra-high molecular weight polyethylene (B) is preferably in the range of 0.930 to 0.960 g/cm ³ .

The weight average molecular weight (Mw) of the ultra-high molecular weight polyethylene (B) may be 500,000 or more.

The melt mass flow rate (MFR) of ultra-high molecular weight polyethylene (B) is less than 0.1g/10min at a temperature of 190°C and a load of 2.16kg, and cannot be measured.

Since ultra-high molecular weight polyethylene (B) has low fluidity upon heating, even if it is melt-kneaded in a sheet-like or pellet-like (granular) state, it is difficult to disperse it in other polyethylene resins and to uniformly melt-mix it. Therefore, the ultra-high molecular weight polyethylene (B) is preferably in a powder form. Examples of the ultra-high molecular weight polyethylene (B) in the form of powder include HI-ZEX MILLION (registered trademark), MIPELON (registered trademark) of Mitsui Chemicals Co., Ltd., and Celanese USA (registered trademark). GUR (registered trademark) of Celanese) Company, etc.

In order to obtain a flat film from a resin composition containing powdered ultra-high molecular weight polyethylene (B), the ultra-high molecular weight polyethylene (B) preferably has an average particle diameter smaller than the thickness of the base material layer 2 . For example, the average particle diameter of ultra-high molecular weight polyethylene (B) is preferably in the range of 5 to 200 μm. The average particle diameter of the ultra-high molecular weight polyethylene (B) is less than 150 μm, and may be 100 μm or less, for example, 25 to 30 μm.

Since ultra-high molecular weight polyethylene (B) has low fluidity even when melt-kneaded at high temperature, it is estimated that the average particle size of the powder of ultra-high molecular weight polyethylene (B) contained in the resin composition before melt-kneading is related to the melting The average particle diameters of the ultra-high molecular weight polyethylene (B) particles contained in the base film after kneading and molding are substantially the same.

For a total of 100 parts by mass of high-density polyethylene (A) and ultra-high molecular weight polyethylene (B), the blending ratio of ultra-high molecular weight polyethylene (B) is preferably in the range of 1 to 23 parts by mass, and may be 1 to 19 parts by mass. within the range of parts by mass, and more preferably within the range of 3 to 12 parts by mass. Therefore, even if the melt fluidity is low, even if ultra-high molecular weight polyethylene (B) in powder form is added to the base layer 2, the processability as a base film can be improved.

The ultra-high molecular weight polyethylene (B) contained in the base material layer 2 may be one type or two or more types. When two or more types of ultra-high molecular weight polyethylene (B) are used, the weight average molecular weight (Mw), average particle diameter, etc. may be different within the above range. The blending ratio of the ultra-high molecular weight polyethylene (B) may be such that the total of two or more ultra-high molecular weight polyethylenes (B) is within the above range.

The base material layer 2 may contain high-density polyethylene (A) in the range of 77 to 99% by mass, and may contain ultra-high molecular weight polyethylene (B) in the range of 1 to 23% by mass. More preferably, the base material layer 2 may contain high-density polyethylene (A) in the range of 88 to 97 mass %, and ultra-high molecular weight polyethylene (B) in the range of 3 to 12 mass %. ). In this case, the total amount of the base material layer 2 or the total amount of the resin components contained in the base material layer 2 can be used as the basis of 100% by mass.

The base material layer 2 may contain additives as necessary within the range of the mixing ratio of the high-density polyethylene (A) and the ultra-high molecular weight polyethylene (B). The additive may be a substance that is compatible with the high-density polyethylene (A) in a molten state, or may be in the form of a powder. The additives are not particularly limited, and examples thereof include ultraviolet absorbers, infrared absorbers, colorants, anti-blocking agents, slip agents, antioxidants, stabilizers, and the like.

In the base material layer 2, the resin component other than additives may be formed only from polyethylene such as high-density polyethylene (A) and ultra-high molecular weight polyethylene (B). As the resin component, the base material layer 2 may contain only high-density polyethylene (A) and ultra-high molecular weight polyethylene (B). When blending other resin components into the base material layer 2, polyethylene-based resins such as medium density polyethylene are preferred, but the content of other resin components is preferably controlled to a minimum.

As an example of the additive, for example, the base material layer 2 may contain masking in a proportion of 5 parts by mass or less based on 100 parts by mass of the high-density polyethylene (A) and the ultra-high molecular weight polyethylene (B) in total. Agent (C). In a packaging bag containing contents requiring light-shielding properties, a masking agent (C) is added to the base material layer 2 . In applications that do not require masking properties, there is no need to add a masking agent (C).

Examples of the masking agent (C) include various pigments such as inorganic pigments and organic pigments. Specific examples of the pigment include black pigments such as titanium-based black pigments, carbon black, and iron black (ferric oxide). In packaging applications for foods, cosmetics, pharmaceuticals, etc., masking agents (C) that are acceptable in terms of hygiene are preferred, and titanium oxide is preferred. When the masking agent (C) is added to the base material layer 2, the mixing ratio is preferably in the range of 1 to 5 parts by mass, and more preferably in the range of 2 to 4 parts by mass.

The laminated film 1 of the embodiment has the sealant layer 4 on one outermost surface. The sealant layer 4 is not particularly limited as long as it is formed of a sealant resin, but polyethylene resin is preferably used as the sealant. Thereby, by making the two laminated films 1 face each other, the sealant layers 4 can be thermally bonded. In addition, since the sealant layer 4 and the base material layer 2 are layers made of polyethylene resin, recyclability is improved.

Examples of polyethylene resins used as sealants include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and the like. The sealant layer can be a single layer or multiple layers. The sealant layer 4 may contain additives as components other than resin. The additives of the sealant layer 4 are not particularly limited, and examples thereof include antioxidants, lubricants, anti-adhesive agents, stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, colorants, and the like.

The manufacturing method of the laminated film 1 according to the embodiment is not particularly limited. The various components constituting the laminated film 1 can be appropriately laminated by extrusion lamination, dry lamination, co-extrusion, or a combination thereof. layer. For example, the base material layer 2 and the sealant layer 4 may be formed into film shapes, and the obtained base material films and sealant films may be laminated by a dry lamination method or the like. Alternatively, the sealant layer 4 may be laminated on the base film by an extrusion lamination method after the base film is molded in advance. In addition, the sealant layer 4 and the base material layer 2 can be molded simultaneously by a co-extrusion method.

When the laminated film 1 is printed, a printing layer may be formed on the inner surface or outer surface of the base film before being laminated with the sealant layer 4 . In addition, after the sealant layer 4 before being laminated with the base material layer 2 is formed into a film shape, a printed layer may be formed on the outer surface of the sealant film. In addition, after the base material layer 2 and the sealant layer 4 are laminated, a printed layer may be formed on the outer surface of the base material layer 2 . You may have a printed layer at two or more places in the thickness direction of the laminated film 1.

In the laminated film 1 of the embodiment, the thickness of the base layer 2 is not particularly limited. It can be designed appropriately according to the use of packaging materials, etc., but it is usually about 10 to 200 μm, preferably 15 to 120 μm. The thickness of the sealant layer 4 is not particularly limited, but is, for example, about 10 to 200 μm, preferably 15 to 120 μm.

The base material layer 2 is preferably formed by melting and kneading high-density polyethylene (A) and ultra-high molecular weight polyethylene (B). During melt-kneading, both high-density polyethylene (A) and ultra-high molecular weight polyethylene (B) may be kneaded in a molten state. When using additives such as the masking agent (C), at least the high-density polyethylene (A) can be kneaded in a molten state.

In addition, the method of molding the base material layer 2 into a film shape is not particularly limited, but it can be molded into a film shape by, for example, an extrusion molding method. According to extrusion molding, a film with a uniform thickness can be easily molded by heating and melting the resin composition to flow without a solvent. In addition, by cooling and solidifying the film of the extruded molten resin quickly, the dispersed state of particles such as ultra-high molecular weight polyethylene (B) or masking agent (C) in the base material layer 2 can be improved.

The film obtained by the step of extruding the base material layer 2 may be a single-layer base material film, or may be a laminated film 1 in which the base material layer 2 and the sealant layer 4 are co-extruded. Examples of methods for forming a film from extruded molten resin include T-die molding, inflation molding, and the like. The laminated film 1 may have two or more base material layers 2 .

A masterbatch containing additives such as ultra-high molecular weight polyethylene (B) or masking agent (C) can be prepared in advance. The masterbatch can be produced by melt-kneading additives such as ultra-high molecular weight polyethylene (B) or a masking agent (C) and high-density polyethylene (A) at a concentration higher than the concentration in the base material layer 2 . In extrusion molding, when the resin composition obtained by melt-kneading the masterbatch and high-density polyethylene (A) is molded, the melt-kneading before extrusion molding can be made more efficient.

After T-die molding, it is preferable to perform heat treatment using a cooling roll when the film immediately after extrusion molding is charged with heat. This is more effective because the base film or the laminated film 1 after molding can be quickly cooled. In the process of cooling the film, the particle shape of the ultra-high molecular weight polyethylene (B) and the dispersion state of the masking agent (C) and the like are fixed, and the uniformity in the molten state can be maintained even after cooling.

When a long film is continuously molded, it is preferable to wind the long molded body of the film after molding because productivity is excellent. In addition, before laminating the base material layer 2 and the sealant layer 4 after molding and film formation, the base material layer 2 may be stretched using methods such as uniaxial stretching or biaxial stretching. This is effective since the strength and thermal deformation resistance of the laminated film 1 are improved. When the base material layer 2 is stretched, pitch deviation can be suppressed when the laminated film 1 is processed into a packaging bag or the like.

For example, in applications that do not require printing on the laminated film 1, since there is no need to consider pitch deviation, etc., the film can be formed without going through a stretching process. When the stretching step is omitted, the adjacent base material layer 2 and sealant layer 4 can be melt-extruded simultaneously by a co-extrusion method.

As shown in FIG. 2 , the laminated film 1 according to the embodiment may have an outer layer 6 made of polyethylene resin on the outside of the base material layer 2 on the side opposite to the sealant layer 4 . The polyethylene resin used to form the outer layer 6 is not particularly limited, and examples thereof include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene ( HDPE) etc. The additives for the outer layer 6 are not particularly limited, and examples thereof include antioxidants, lubricants, anti-adhesive agents, stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, colorants, and the like. The outer layer 6 may be a layer that is not thermally bonded to the sealant layer 4 at the same time, and the laminated film 1 may have the sealant layer 4 on only one side. The outer layer 6 may be a layer capable of thermal bonding in the same manner as the sealant layer 4 , and the laminated film 1 may have the sealant layer 4 on both sides.

There is no particular limitation on the manufacturing method of the laminated film 1 having three resin layers: the sealant layer 4, the base material layer 2, and the outer layer 6. Each resin layer can be formed into a film in any order. Alternatively, two or more layers may be filmed simultaneously and then laminated. Since the sealant layer 4, the base material layer 2, and the outer layer 6 are each made of polyethylene resin, recyclability is improved.

For example, each resin layer may be formed into a film and then laminated by a dry lamination method or the like.

In addition, the sealant layer 4 or the outer layer 6 may be laminated on the base material layer 2 by an extrusion lamination method after the base material layer 2 is formed into a film in advance. In addition, the three layers of sealant layer 4, base material layer 2, and outer layer 6 can be molded simultaneously by a coextrusion method. After the sealant layer 4 and the base material layer 2 are laminated in advance, the outer layer 6 may be laminated on the outside of the base material layer 2 . After the outer layer 6 and the base material layer 2 are laminated first, the sealant layer 4 may be laminated inside the base material layer 2 .

The use of the laminated film 1 of the embodiment is not particularly limited, and it can be used to manufacture containers such as packaging bags. The packaging bag is not particularly limited, and examples thereof include pouches, bags, three-side sealing bags, four-side sealing bags, pillow bags, gusset bags, stand-up bags, and the like. The packaging container may be formed only of the laminated film 1 of the embodiment, or the laminated film 1 may be combined with accessory components such as labels, tags, straws, and spouts.

3 is a front view showing a stand-up pouch 10 as an example of a packaging bag using the laminated film 1. The stand-up pouch 10 includes a hollow container body 12 and a spout member 14 attached to one end of the container body 12. . For example, the container main body 12 is formed of two main body film 16 and bottom film 18 each having the same rectangular planar shape. The main body film 16 and the bottom film 18 are both formed from the laminated film 1 , and the outer edge portions of the respective sealant layers 4 are heat-welded to each other to form a heat-sealed portion 20 . Thereby, the container main body 12 has a bag shape as a whole, and the contents can be put in and out of the container main body 12 through the spout member 14, and it has a flat shape that is flattened when no contents are put therein. It should be noted that the present invention is not limited to stand-up bags, but can be applied to various packaging bags using laminates, and can provide a single material that has good heat deformation resistance, impact resistance, and embrittlement resistance. Packaging bags.

When the packaging bag is composed of two or more types of members, the laminated film 1 of the embodiment is used for one or more specific components, and other laminated films or single-layer films can be used for other components. Since the laminated film 1 of the embodiment is excellent in strength, it can be used not only for small packaging bags but also for manufacturing large packaging bags capable of storing heavy contents.

The state of the content is not particularly limited, and examples include liquid, powder, granular, solid, and the like. The type of contents is not particularly limited, and examples thereof include detergents, chemicals, cosmetics, pharmaceuticals, foods, beverages, seasonings, inks, paints, fuels, and the like. The packaging bag can contain two or more contents in a mixed state or two or more contents separately. The packaging bag may have one space for storing contents, or may have two or more spaces.

According to the embodiment, it is possible to provide the laminated film 1 and the packaging bag 10 having excellent heat deformation resistance, impact resistance, and embrittlement resistance among the laminated film 1 and the packaging bag having the base material layer 2 of polyethylene resin.

As mentioned above, the present invention has been described based on preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the present invention.

Since the laminated film of the embodiment is a resin film mainly composed of polyethylene, its use is not limited to packaging bags and can be used for various purposes such as packaging, display, testing, storage, and shielding.

[Example]

Hereinafter, this invention is demonstrated concretely based on an Example.

(Method for forming base film)

Based on the composition of the base material layer shown in Table 1, the resin was melt-kneaded, and a single-layer base film as the base material layer was extruded with a thickness of 100 μm using a T-die extruder. In Table 1, the basis of parts by mass is that the total of high-density polyethylene (A) and ultra-high molecular weight polyethylene (B) as resins is 100 parts by mass.

【Table 1】

It should be noted that the abbreviations used in Table 1 have the following meanings.

"HDPE1" is a high-density polyethylene with density ρ=0.949g/cm ³ , melting point Tm=130°C, and melt mass flow rate MFR=1.1g/10min (temperature 190°C and load 2.16kg).

"HDPE2" is a high-density polyethylene with density ρ=0.952g/cm ³ , melting point Tm=129°C, and melt mass flow rate MFR=21g/10min (temperature 190°C and load 2.16kg).

"UHMWPE1" is an ultra-high molecular weight polyethylene powder (manufactured by Mitsui Chemicals Co., Ltd., trade name MIPELON (registered trademark)) with a density ρ = 0.940 g/cm ³ , a melting point Tm = 136° C., an average particle diameter of 30 μm, and a weight average molecular weight of 2 million. XM-220).

"UHMWPE2" is an ultra-high molecular weight polyethylene powder with a density ρ = 0.940 g/cm ³ , a melting point Tm = 136° C., an average particle diameter of 25 μm, and a weight average molecular weight of 2 million (manufactured by Mitsui Chemicals Co., Ltd., trade name MIPELON (registered trademark) XM-221U).

"Titanium oxide" is titanium oxide powder with a TiO2 content of 95% and an average particle diameter of 25 μm (manufactured by Ishihara Sangyo Co., Ltd., trade name CR-Super70).

(Evaluation method of base film)

(1)Measurement method of melt mass flow rate (MFR)

The base film formed to have a thickness of 100 μm was pulverized to obtain a measurement sample. For Comparative Examples 1 and 2 in which the composition of the base material layer is composed of one type of resin, high-density polyethylene particles used in the molding process of the base film were directly used as measurement samples. For each measurement sample, the melt mass flow rate (MFR) value (g/10 minutes) was measured under the conditions of a temperature of 300° C. and a load of 2.16 kg. The MFR value of the base film is an index of processability and heat deformation resistance.

(2)Measurement method of the number of bends

The base film molded to a thickness of 100 μm was cut into a size of 15 mm in width and 100 mm in length to obtain a measurement sample. For the measurement sample, an MIT bending endurance tester (manufactured by TESTER SANGYO Co., Ltd.) was used to repeatedly bend a bending angle of 135° with a force of 1.5kgf {14.7N}, and the bending until fracture was measured. frequency. The value of the number of bends of the base film is an index of impact resistance and embrittlement resistance.

(3) Evaluation method of thermal deformation

The base film molded to a thickness of 100 μm was cut into a size of 15 mm in width and 100 mm in length to obtain a measurement sample. Place the measurement sample on a hot plate at a temperature of 150°C for 1 minute, and visually confirm whether there is thermal shrinkage or warping. When no thermal shrinkage or warping was observed in the base film, it was evaluated as "no thermal deformation", and when thermal shrinkage or warping was observed in the base film, it was evaluated as "the presence of thermal deformation".

(Evaluation results of base film)

Table 2 shows the evaluation results of the base film.

【Table 2】

According to Examples 1 to 8, by setting the composition of the base layer to a predetermined range, a base film having a thickness of 100 μm can be produced by extrusion molding. In addition, in the compositions of Examples 1 to 8, the value of the melt mass flow rate (MFR) under the conditions of a temperature of 300°C and a load of 2.16 kg was small, and it was not confirmed under the conditions of a temperature of 150°C and a load of 1 minute. Heat shrinkage and warping, so the heat deformation resistance of the base film is improved. In addition, since the base film of Examples 1 to 8 has a large number of bending times, the impact resistance and embrittlement resistance are improved.

According to Comparative Example 1, although high-density polyethylene (HDPE1) has heat deformation resistance to the extent that the value of the melt mass flow rate (MFR) can be measured under the conditions of a temperature of 300°C and a load of 2.16 kg, it fails at a temperature of 150°C. Thermal shrinkage and warping of the base film occurred under the conditions of 1 minute at ℃. In addition, in the base film of Comparative Example 1, the number of times of bending was reduced.

According to Comparative Example 2, high-density polyethylene (HDPE2) has excessive fluidity at a high temperature of 300°C, and the value of the melt mass flow rate (MFR) under the conditions of a temperature of 300°C and a load of 2.16 kg cannot be measured. In addition, in Comparative Example 2, thermal shrinkage and warping of the base film occurred under the conditions of 150° C. and 1 minute. In addition, in the base film of Comparative Example 2, the number of bends was significantly reduced.

According to Comparative Example 3, although titanium oxide was blended with high-density polyethylene (HDPE1) in the same manner as Comparative Example 1, thermal shrinkage and warping of the base film occurred under the conditions of 150° C. and 1 minute. In addition, in the base film of Comparative Example 3, the number of bends of the base film was reduced.

According to Comparative Example 4, the fluidity of the molten resin was low, and a base film having a thickness of 100 μm could not be produced. Therefore, the melt mass flow rate (MFR) and the number of bends under the conditions of a temperature of 300° C. and a load of 2.16 kg could not be measured, and the thermal deformation properties could not be evaluated.

The number of bending times shown in Table 2 is considered to be affected by the presence or absence of titanium oxide. When comparing the base material films of Examples 1 and 3 without titanium oxide and Comparative Example 1, the number of bending times of the base film of Examples 1 and 3 is the number of bending times of the base film of Comparative Example 1. More than 2 times. If the base material films of Examples 2 and 4 and Comparative Example 3 containing titanium oxide are compared, the number of bending times of the base material films of Examples 2 and 4 is the number of bending times of the base material film of Comparative Example 2. About 1.5 times.

(How to make laminated film)

When the base material film was melt-extruded according to the composition of the base material layer of Examples 1 to 8 shown in Table 1, the sealant layer was laminated by co-extrusion to produce a base material layer with a thickness of 100 μm and a sealant layer with a thickness of 50 μm. The sealant layer is a laminated film of these two layers.

Among the materials for the sealant layer, those with density ρ = 0.937g/cm ³ , melting point Tm = 126°C, and melt mass flow rate MFR = 3.5g/10min (under the conditions of temperature 190°C and load 2.16kg) were used. Metallocene catalyst polymerizes C6-LLDPE.

(Manufacture of packaging bags)

Using the above laminated film in which the sealant layer was laminated on the base material layer of Examples 1 to 8 by co-extrusion, a three-sided sealed bag was produced under the conditions of heat sealing temperature of 160° C., sealing pressure of 0.2 MPa, and sealing time of 1 sec. When the packaging bags having the base material layers of Examples 1 to 8 were produced, thermal deformation of the laminated film due to heating of the sealing portion was not confirmed.

Industrial availability

According to the present invention, a laminated film and a packaging bag having a base material layer of a polyethylene resin can be provided that are excellent in heat deformation resistance, impact resistance, and embrittlement resistance, and therefore have industrial feasibility. Exploitability.

Claims (9)

1. A laminated film, characterized in that it includes a base material layer and a sealant layer forming the outermost surface of one side of the laminated film, The base material layer contains 77-99 parts by mass of high-density polyethylene (A) and 1-23 parts by mass of high-molecular-weight polyethylene (B), totaling 100 parts by mass. The ultra-high-density polyethylene (A) The density is 0.942~0.970g/cm ³ , the melt mass flow rate is 0.1~3.0g/10min under the conditions of a temperature of 190°C and a load of 2.16kg, and the density of the ultra-high molecular weight polyethylene (B) is 0.930 ~0.960g/cm ³ . 2. The laminated film according to claim 1, characterized in that: The ultra-high molecular weight polyethylene (B) of the base material layer has an average particle diameter of 5 to 200 μm, and a weight average molecular weight of 500,000 or more. 3. The laminated film according to claim 1 or 2, characterized in that: The base material layer contains the masking agent (C) in a proportion of 5 parts by mass or less. 4. The laminated film according to claim 3, characterized in that: The masking agent (C) is titanium oxide. 5. The laminated film according to any one of claims 1 to 4, characterized in that: The sealant layer is a layer made of polyethylene resin. 6. The laminated film according to any one of claims 1 to 5, characterized in that: The base material layer has a layer made of polyethylene resin on the opposite side to the sealant layer. 7. The laminated film according to any one of claims 1 to 6, characterized in that: The base material layer is formed of a resin composition obtained by melting and kneading the high-density polyethylene (A) and the ultra-high molecular weight polyethylene (B). 8. The laminated film according to any one of claims 1 to 7, characterized in that: The base material layer is formed into a film shape by extrusion molding. 9. A packaging bag, characterized in that: It is formed using the laminated film according to any one of claims 1 to 8.