KR102633198B1 - Multi-layer film for liquid food packaging and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a multilayer film for liquid food packaging manufactured by laminating a first film and a second film, wherein the first film includes an outer layer containing first low-density polyethylene and medium-density polyethylene; A middle layer comprising a second low-density polyethylene and a first polyolefin plastomer; and an inner layer containing a second polyolefin plastomer, wherein the second film is a nylon film and is laminated with the outer layer of the first film.

Description

Multilayer film for liquid food packaging and manufacturing method thereof {Multi-layer film for liquid food packaging and manufacturing method thereof}

The present invention relates to a multilayer film for packaging liquid food and a method of manufacturing the same.

In general, containers made of metal, glass, hardened plastic, etc. for packaging liquid phase materials are standardized to have a certain shape, so even when the contents are empty, they always occupy a certain area without external pressure and are resistant to external shocks. It has the disadvantage of being difficult to store and transport because it is broken or damaged by .

As a way to overcome the various shortcomings of these inflexible containers, flexible containers using synthetic resin film materials are receiving attention.

In particular, flexible containers for packaging liquid food must have high transparency so that the condition of the food can be checked, must not have a harmful effect on the food, and must not be easily damaged by external impact. Research continues to develop films for packaging liquid food.

Meanwhile, Republic of Korea Patent Publication No. 10-2020-0062251 is presented as a similar prior document.

Republic of Korea Patent Publication No. 10-2020-0062251 (2020.06.03)

In order to solve the above problems, the present invention provides a multilayer film for packaging liquid food that has excellent sealing strength even at low sealing temperatures during high-speed packaging, has high transparency, and is not easily damaged by external impact, and a method for manufacturing the same. The purpose.

However, the above object is illustrative, and the technical idea of the present invention is not limited thereto.

One aspect of the present invention for achieving the above object is a multilayer film manufactured by laminating a first film and a second film, wherein the first film includes an outer layer including a first low-density polyethylene and a medium-density polyethylene; A middle layer comprising a second low-density polyethylene and a first polyolefin plastomer; and an inner layer containing a second polyolefin plastomer, wherein the second film is a nylon film and is laminated with the outer layer of the first film.

In the above aspect, the outer layer of the first film is an agent that satisfies a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C. 1 It may include low-density polyethylene and medium-density polyethylene that satisfies a density of 0.926 to 0.940 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 100 to 130°C. .

In the above aspect, the middle layer of the first film is an agent that satisfies a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C. 2 Comprising low-density polyethylene and a first polyolefin plastomer satisfying a density of 0.885 to 0.910 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 70 to 100°C. It may be.

In the above aspect, the inner layer of the first film is an agent that satisfies a density of 0.850 to 0.879 g/cm3, a melt index of 0.3 to 5.0 g/10 min (2.16 kg, 190°C), and a melting point of 50 to 75°C. 2Polyolefin plastomer, or a second polyolefin plastomer satisfying a density of 0.880 to 0.900 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 65 to 85°C. It may include

In addition, another aspect of the present invention is a) a co-extrusion method, wherein the outer layer includes the first low-density polyethylene and the middle-density polyethylene, the middle layer includes the second low-density polyethylene and the first polyolefin plastomer, and the second polyolefin plastomer. Manufacturing a first film including an inner layer including a stormer; and b) laminating the outer layer of the first film and the nylon film so that they come into contact with each other.

The multilayer film for liquid food packaging according to the present invention has excellent sealing strength even at low sealing temperatures during high-speed packaging, has low gas permeability and moisture permeability, so that food does not easily deteriorate, and has high transparency, so it is easy to check whether packaged food deteriorates. It can be checked and has the advantage of not being easily damaged by external shock.

Figure 1 is a diagram briefly illustrating a multilayer film for packaging liquid food according to an example of the present invention.

Hereinafter, the multilayer film for liquid food packaging and its manufacturing method according to the present invention will be described in detail. The drawings introduced below are provided as examples so that the idea of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, if there is no other definition in the technical and scientific terms used, they have the meaning commonly understood by those skilled in the art to which this invention pertains, and the gist of the present invention is summarized in the following description and attached drawings. Descriptions of known functions and configurations that may be unnecessarily obscure are omitted.

One aspect of the present invention relates to a multilayer film manufactured by laminating a first film and a second film. In detail, the first film includes an outer layer including a first low-density polyethylene and a medium-density polyethylene; A middle layer comprising a second low-density polyethylene and a first polyolefin plastomer; and an inner layer containing a second polyolefin plastomer, wherein the second film is a nylon film and is laminated with the outer layer of the first film.

Accordingly, the multilayer film for liquid food packaging according to the present invention can have excellent sealing properties during high-speed packaging, and has low gas permeability and moisture permeability, so food may not easily deteriorate, and its high transparency makes it easy to check whether packaged food deteriorates. It can be checked and has the advantage of not being easily damaged by external shock.

Hereinafter, a multilayer film for packaging liquid food according to an example of the present invention will be described in more detail.

As described above, the first film according to an example of the present invention may be composed of a three-layer structure of an outer layer, a middle layer, and an inner layer. In this case, the thickness of the outer layer may be 5 to 15 ㎛, and the thickness of the middle layer may be 15 to 15 ㎛. 25 ㎛, the thickness of the inner layer may be 5 to 15 ㎛. Through this, it has low gas permeability and moisture permeability, so food does not easily deteriorate, and it has excellent transparency, so it is easy to check whether packaged food has deteriorated.

The outer layer of the first film is a first low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.926 g/cm3. It may include medium density polyethylene satisfying a density of ~0.940 g/cm3, a melt index of 0.5~5.0 g/10 min (2.16 kg, 190°C), and a softening point of 100~130°C, and more preferably 0.915~0.925. First low-density polyethylene satisfying a density of g/cm3, a melt index of 0.5~3.0 g/10 min (2.16 kg, 190°C), and a softening point of 98~110°C, and a density of 0.930~0.940 g/cm3, 0.5~ It may include medium density polyethylene that satisfies a melt index of 3.0 g/10 minutes (2.16 kg, 190°C) and a softening point of 115-125°C. By satisfying this, it can be effectively laminated with the second film in the future, preventing the layers from easily peeling off, and ensuring excellent gas and moisture barrier properties and toughness.

At this time, the weight ratio of the first low-density polyethylene:medium-density polyethylene may be 90:10 to 10:90, and more preferably 80:20 to 50:50. The desired effect can be maximized by using a mixture of the first low-density polyethylene and the medium-density polyethylene that satisfy the physical property index in this ratio.

The middle layer of the first film is a second low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.885 g/cm3. It may include a first polyolefin plastomer (first POP) that satisfies a density of ~0.910 g/cm3, a melt index of 0.3~5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 70~100°C. , more preferably a second low-density polyethylene satisfying a density of 0.915 to 0.925 g/cm3, a melt index of 0.5 to 3.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 98 to 110°C, and 0.895 to 0.905 g. It may include a first polyolefin plastomer (first POP) that satisfies a density of /cm3, a melt index of 0.3 to 3.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 80 to 90°C. By satisfying this, the outer layer, middle layer, and inner layer can be well co-extruded into a triple layer.

At this time, the weight ratio of the second low-density polyethylene:the first POP may be 80:20 to 20:80, more preferably 70:30 to 30:70, and even more preferably 60:40 to 40:60. The desired effect can be maximized by using a mixture of the first low-density polyethylene and the first POP that satisfy the physical property index in this ratio.

In addition, the inner layer of the first film is a second polyolefin plastomer that satisfies a density of 0.850 to 0.879 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 50 to 75°C. (2nd POP), or a second polyolefin plastomer satisfying a density of 0.880 to 0.900 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 65 to 85°C. 2POP), and more preferably, a second POP that satisfies a density of 0.860 to 0.875 g/cm3, a melt index of 0.3 to 3.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 55 to 65°C, Alternatively, it may include a second POP that satisfies a density of 0.880 to 0.890 g/cm3, a melt index of 0.3 to 3.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 70 to 80°C. By satisfying this, excellent sealing properties can be secured during high-speed packaging.

At this time, the density of the polymer material was measured according to ASTM D792, the melt index (2.16 kg, 190°C) was measured according to ASTM D1238, the melting point was measured according to ASTM D3418, and the Vicat softening point is measured according to ASTM D1525.

Meanwhile, the inner layer of the first film according to an example of the present invention may further include surface-modified zinc oxide nanoparticles. The surface-modified zinc oxide nanoparticles are intended to provide antibacterial and anti-fungal performance to the multilayer film, and may be surface-modified with silicone oil. Through this, agglomeration between particles is prevented, and excellent antibacterial and anti-fungal properties can be secured even by adding a small amount of the above ingredients, and can be well mixed with polyolefin plastomer. On the other hand, if the surface is not modified with silicone oil, the above components must be added twice or more to secure similar antibacterial and antifungal properties. In this case, the properties such as gas permeability and toughness of the multilayer film may be reduced, which is not good.

More specifically, the zinc oxide nanoparticles may be surface modified with silicone oil having an HLB of 3 to 8, and preferably, may be surface modified with a silicone oil having an HLB of 4 to 7. Through this, the agglomeration phenomenon between particles can be prevented particularly effectively, while miscibility with polyolefin plastomer can be excellent. On the other hand, when using silicone oil with HLB less than 3 or more than HLB 8, the miscibility between the particles and the polyolefin plastomer resin after surface modification is poor, which may worsen the agglomeration phenomenon between particles, resulting in a decrease in antibacterial and anti-fungal properties. In addition, the tensile strength and elongation rate may be lowered.

As a specific example, the silicone oil is dimethicone, PEG-3 dimethicone, PEG-10 dimethicone, PEG/PPG-20/22 butyl ether dimethicone, cetyl PEG/PPG-10/1 dimethicone, PEG-9 It may be any one or two or more selected from the group consisting of polydimethylsiloxyethyl dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, etc.

Additionally, the viscosity of the silicone oil at 25°C may be 100 to 1000 cS, and more preferably 400 to 800 cS. In this range, the surface modification effect of the zinc oxide nanoparticles may be excellent.

In addition, the zinc oxide nanoparticles before surface modification may be nano-sized zinc oxide particles with an average particle size of 1 to 100 nm, more preferably 5 to 50 nm. In this range, it has excellent antibacterial and anti-fungal performance and can be mixed well with polyolefin plastomer resin.

The surface-modified zinc oxide nanoparticles may be added in an amount of 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight, and even more preferably 1 to 10 parts by weight, based on 100 parts by weight of the inner layer resin (second polyolefin plastomer) of the first film. It can be added in 3 to 8 parts by weight. In the above range, antibacterial and antifungal properties are excellent. On the other hand, when surface-modified zinc oxide nanoparticles are added in less than 0.5 parts by weight, antibacterial properties may be minimal, and when added in more than 15 parts by weight, haze increases.

In addition, the inner layer may further include surface-modified calcium oxide, which can further improve antibacterial and antifungal properties. The surface-modified calcium oxide may be surface-modified with silicone oil. In detail, it may be surface-modified with a silicone oil with an HLB of 3 to 8, and preferably with a silicone oil with an HLB of 4 to 7. . Through this, it is possible to effectively prevent agglomeration between particles and have excellent miscibility with polyolefin plastomer. On the other hand, when using silicone oil with HLB less than 3 or more than HLB 8, the miscibility between the particles and the polyolefin plastomer resin after surface modification is poor, which may worsen the agglomeration phenomenon between particles, resulting in a decrease in antibacterial and anti-fungal properties. In addition, the tensile strength and elongation rate may be lowered.

As a specific example, the silicone oil is dimethicone, PEG-3 dimethicone, PEG-10 dimethicone, PEG/PPG-20/22 butyl ether dimethicone, cetyl PEG/PPG-10/1 dimethicone, PEG-9 It may be any one or two or more selected from the group consisting of polydimethylsiloxyethyl dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, etc., and is the same as or different from the silicone oil surface-modified with zinc oxide nanoparticles. can do.

Additionally, the viscosity of the silicone oil at 25°C may be 100 to 1000 cS, and more preferably 400 to 800 cS. In this range, the surface modification effect of the calcium oxide particles may be excellent.

In addition, the calcium oxide before surface modification may have an average particle size of 10 to 300 nm, and more preferably 50 to 200 nm. In this range, it has excellent antibacterial and anti-fungal performance and can be mixed well with polyolefin plastomer resin. At this time, the calcium oxide may be manufactured by calcining the shell. Specifically, for example, the shell may be calcined at 900 to 1250°C for 1 to 10 hours, or better, at 1000 to 1200°C for 3 to 5 hours. there is. Through this, problems such as decay caused by organic matter remaining in the shell can be prevented without consuming too much energy in the firing of the shell. Afterwards, calcium oxide powder satisfying the above particle size range can be obtained through several stages of grinding.

The surface-modified calcium oxide may be added in an amount of 0.1 to 8 parts by weight, more preferably 0.5 to 5 parts by weight, and even more preferably 1 to 100 parts by weight of the inner layer resin (second polyolefin plastomer) of the first film. It can be added in 3 parts by weight. In the above range, antibacterial and antifungal properties are excellent.

In addition, the inner layer may further include functional additives as needed. Specifically, for example, it may further include one or more functional additives selected from the group consisting of slip agents, anti-blocking agents, anti-blocking agents, etc.

The slip agent is added to improve the slipperiness of the inner layer surface and prevent adhesion to adjacent inner layer surfaces, and is from the group consisting of erucamide, stearamide, oliamide, etc. There may be one or more than one selected. The addition amount is not particularly limited as long as it is a level commonly used in the industry. As a non-limiting example, it may be added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the inner layer resin (second polyolefin plastomer) of the first film. .

The anti-blocking agent is added to improve the roughness of the inner layer surface to prevent adhesion to adjacent inner layer surfaces, and may be any one or two or more selected from the group consisting of mica, talc, calcium carbonate, zeolite, and silica. there is. The amount added is not particularly limited as long as it is commonly used in the industry. As a non-limiting example, it may be added in an amount of 1 to 10 parts by weight based on 100 parts by weight of the inner layer resin (second polyolefin plastomer) of the first film. .

The second film according to the present invention is laminated on the outer layer of the first film, and the second film may be a nylon film, specifically made of nylon 6, nylon 66, nylon 6-nylon 66 copolymer, and nylon 610. It may be any one or two or more selected from the group. Through this, the mechanical properties and gas and moisture barrier properties of the multilayer film are further improved, preventing it from being easily damaged by external shocks, and at the same time, deterioration of packaged liquid food can be more effectively prevented. At this time, the thickness of the second film may be 10 to 20 ㎛.

In addition, another aspect of the present invention is a) a co-extrusion method, wherein the outer layer includes the first low-density polyethylene and the middle-density polyethylene, the middle layer includes the second low-density polyethylene and the first polyolefin plastomer, and the second polyolefin plastomer. Manufacturing a first film including an inner layer including a stormer; and b) laminating the outer layer of the first film and the nylon film so that they come into contact with each other.

First, by co-extrusion, an outer layer containing the first low-density polyethylene and the middle-density polyethylene, a middle layer containing the second low-density polyethylene and the first polyolefin plastomer, and an inner layer containing the second polyolefin plastomer. The first film can be manufactured.

At this time, since the polymer materials used in each layer are the same as described above, redundant description will be omitted, and their co-extrusion can be performed under conditions commonly used in the art.

Next, a multilayer film for liquid food packaging can be manufactured by laminating the outer layer of the first film and the nylon film in contact with each other. The lamination process can be used without particular limitation as long as it is a method commonly used in the industry, such as solvent-type bonding or non-solvent bonding. For example, solvent-type bonding is a method of dissolving an adhesive in a solvent. A representative solvent may be water, and the first film and the second film are bonded through dry lamination or wet lamination. can do. For dry bonding or double bonding, adhesives such as water-dispersed polyurethane, acrylic emulsion, or water-based polyvinyl alcohol can be used. On the other hand, solvent-free bonding is a method that does not use solvents, and adhesives such as one-component polyurethane-based or two-component polyurethane-based adhesives can be used.

Hereinafter, the multilayer film for liquid food packaging and its manufacturing method according to the present invention will be described in more detail through examples. However, the following examples are only a reference for explaining the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Additionally, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The terminology used in the description herein is merely to effectively describe particular embodiments and is not intended to limit the invention. Additionally, the unit of additives not specifically described in the specification may be weight percent.

[Production Example 1]

For 100 parts by weight of zinc oxide nanoparticles (average particle size 50 nm), 20 parts by weight of PEG-10 dimethicone (BRB 6341, viscosity 600 cS at 25°C, HLB 4.5) was added, and the mixture was mixed at a speed of 800 rpm using a super mixer. After stirring, filtering and drying were performed to prepare surface-modified zinc oxide nanoparticles.

[Production Example 2]

The scallop shells were fired at a temperature of 1100°C for 3 hours, then placed in a multi-purpose grinder and first pulverized to have an average particle diameter of 100 ㎛. The primary crushed scallop shells were fired again at a temperature of 1100°C for 2 hours, then secondary crushed to an average particle diameter of 2 ㎛ through a dry ball mill process, and then ball milled again to oxidize with an average particle diameter of 100 ㎚. Calcium was prepared.

Next, 20 parts by weight of PEG-10 dimethicone (BRB 6341, viscosity 600 cS at 25°C, HLB 4.5) was added to 100 parts by weight of the calcium oxide, and stirred at a speed of 800 rpm using a super mixer. , filtered and dried to prepare surface-modified calcium oxide.

[Production Examples 3 and 4]

Except for using cyclopentasiloxane and PEG/PPG-18/18 dimethicone (BRB 6373, viscosity 30 cS at 25°C, HLB 2) as silicone oil, all processes were carried out in the same manner as in Preparation Examples 1 and 2 to produce a surface-modified product. Zinc oxide nanoparticles (Preparation Example 3) and surface-modified calcium oxide (Preparation Example 4) were prepared.

[Production Examples 5 and 6]

Except for using PEG-12 dimethicone (SM3220P, viscosity 250-600 cS at 25°C, HLB 13) as silicone oil, all processes were carried out in the same manner as Preparation Examples 1 and 2 to produce surface-modified zinc oxide nanoparticles (Preparation Example 5) and surface-modified calcium oxide (Preparation Example 6) were prepared.

[Comparative Manufacturing Examples 1 and 2]

Zinc oxide nanoparticles (Comparative Preparation Example 1) and calcium oxide (Comparative Preparation Example 2) without surface modification were prepared.

[Example 1]

80 parts by weight of first low-density polyethylene (first LDPE) having a density of 0.919 g/cm3, a melt index of 1.0 g/10 minutes (2.16 kg, 190°C), and a Vicat softening point of 102°C as the outer layer material of the first film; , was prepared by mixing 20 parts by weight of medium density polyethylene (MDPE) with a density of 0.935 g/cm3, a melt index of 1.0 g/10 min (2.16 kg, 190°C), and a Vicat softening point of 123°C.

The middle layer material includes 50 parts by weight of second low-density polyethylene (second LDPE) having a density of 0.919 g/cm3, a melt index of 0.9 g/10 minutes (2.16 kg, 190°C), and a Vicat softening point of 102°C, and 0.902 g. It was prepared by mixing 50 parts by weight of the first polyolefin plastomer (first POP) having a density of /cm3, a melt index of 1.0 g/10 minutes (2.16 kg, 190°C), and a Vicat softening point of 85°C.

As the inner layer material, 100 parts by weight of the second polyolefin plastomer (second POP) having a density of 0.868 g/cm3, a melt index of 1.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 62°C was prepared in Preparation Example 1. It was prepared by mixing 2.5 parts by weight of the surface-modified zinc oxide nanoparticles, 1.0 parts by weight of the surface-modified calcium oxide of Preparation Example 2, and 1.0 parts by weight of erucamide.

These were co-extruded to produce a first film with an outer layer of 10 ㎛, a middle layer of 20 ㎛, and an inner layer of 10 ㎛.

Next, a polyurethane adhesive was applied to the outer layer of the first film and then a second film (nylon 6, thickness 15 ㎛) was laminated to prepare a multilayer film according to the present invention.

[Example 2]

All processes except using 100 parts by weight of the second polyolefin plastomer (third POP) with a density of 0.885 g/cm3, a melt index of 1.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 74°C as the inner layer material. A multilayer film was manufactured in the same manner as in Example 1.

[Example 3]

All processes were performed in the same manner as in Example 1, except that 50 parts by weight of the first low-density polyethylene (1st LDPE) and 50 parts by weight of the medium-density polyethylene (MDPE) of Example 1 were used as the outer layer material of the first film to produce a multilayer film. was manufactured.

[Example 4]

All processes were carried out in the same manner as in Example 1, except that 20 parts by weight of the first low-density polyethylene (1LDPE) and 80 parts by weight of the medium-density polyethylene (MDPE) of Example 1 were used as the outer layer material of the first film to produce a multilayer film. was manufactured.

[Example 5]

All processes were the same as in Example 1 except that 80 parts by weight of the second low-density polyethylene (2nd LDPE) of Example 1 and 20 parts by weight of the first polyolefin plastomer (1st POP) were used as the middle layer material of the first film. Proceed to produce a multilayer film.

[Example 6]

All processes were the same as in Example 1 except that 20 parts by weight of the second low-density polyethylene (2nd LDPE) of Example 1 and 80 parts by weight of the first polyolefin plastomer (1st POP) were used as the middle layer material of the first film. Proceed to produce a multilayer film.

[Comparative Example 1]

A multilayer film (=first film) without nylon film was prepared.

[Comparative Example 2]

A multilayer film was manufactured in the same manner as in Example 1, except that 100 parts by weight of the first low-density polyethylene (1LDPE) of Example 1 was used as the outer layer material of the first film.

[Comparative Example 3]

A multilayer film was manufactured in the same manner as in Example 1 except that 100 parts by weight of the medium density polyethylene (MDPE) of Example 1 was used as the outer layer material of the first film.

[Comparative Example 4]

A multilayer film was manufactured in the same manner as in Example 1, except that 100 parts by weight of the second low-density polyethylene (2LDPE) of Example 1 was used as the middle layer material of the first film.

[Comparative Example 5]

A multilayer film was manufactured in the same manner as in Example 1 except that 100 parts by weight of the first polyolefin plastomer (1st POP) of Example 1 was used as the middle layer material of the first film.

[Comparative Example 6]

As the inner layer material of the first film, 100 parts by weight of the second polyolefin plastomer (No. 4 POP), which has a density of 0.902 g/cm3, a melt index of 1.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 100°C, was used. All other processes were performed in the same manner as in Example 1 to produce a multilayer film.

1st film 2nd film
existence and nonexistence Outer layer (part by weight) Middle layer (part by weight) inner layer 1LDPE MPPE 2LDPE 1stPOP type Melting point (℃) weight part ◎ Example 1 80 20 50 50 2ndPOP 62 100 ◎ Example 2 80 20 50 50 3rdPOP 74 100 ◎ Example 3 50 50 50 50 2ndPOP 62 100 ◎ Example 4 20 80 50 50 2ndPOP 62 100 ◎ Example 5 80 20 80 20 2ndPOP 62 100 ◎ Example 6 80 20 20 80 2ndPOP 62 100 ◎ Comparative Example 1 80 20 50 50 2ndPOP 62 100 x Comparative Example 2 100 - 50 50 2ndPOP 62 100 ◎ Comparative Example 3 - 100 50 50 2ndPOP 62 100 ◎ Comparative Example 4 80 20 100 - 2ndPOP 62 100 ◎ Comparative Example 5 80 20 - 100 2ndPOP 62 100 ◎ Comparative Example 6 80 20 50 50 3POP 100 100 ◎

[Characteristics Evaluation]

1) Sealing strength (N/15 mm): Heat sealing strength was evaluated at 80°C, 90°C, 100°C, and 110°C based on ASTM F 1921, and the results are shown in Table 2 below.

2) Tensile strength (MPa) and elongation (%): Evaluated according to ASTM D638, and the results are shown in Table 2 below.

Heat sealing strength (N/15㎜) tensile strength
(㎫) elongation rate
(%) 80℃ 90℃ 100℃ 110℃ Example 1 37.2 54.3 56.1 58.4 19.2 241 Example 2 12.5 28.7 52.9 57.9 20.4 235 Example 3 36.4 53.1 54.6 57.6 18.9 240 Example 4 37.0 53.9 55.5 57.2 18.2 230 Example 5 36.5 53.4 54.6 55.3 18.6 217 Example 6 36.1 54.2 56.3 57.8 18.0 223 Comparative Example 1 37.0 54.2 56.0 58.1 16.5 211 Comparative Example 2 36.2 53.8 55.4 57.2 17.4 222 Comparative Example 3 36.4 54.5 56.0 57.8 18.1 219 Comparative Example 4 37.1 54.1 56.3 58.2 17.2 213 Comparative Example 5 36.6 53.8 55.9 58.0 18.0 211 Comparative Example 6 < 1 < 1 2.9 50.9 18.7 237

Referring to Tables 1 and 2 above, the multilayer film manufactured to satisfy the claims had a high heat sealing strength of 50 N/15 mm or more even at a lower temperature, and also had excellent tensile strength and elongation.

[Examples 7 to 12 and Comparative Examples 7 to 8]

As shown in Table 3 below, instead of 2.5 parts by weight of the surface-modified zinc oxide nanoparticles of Preparation Example 1 and 1.0 parts by weight of the surface-modified calcium oxide of Preparation Example 2, Preparation Examples 2 to 6 or Comparative Preparation Examples 1 to 2 were used. All processes were carried out in the same manner as in Example 1 except that zinc oxide nanoparticles and calcium oxide were used in the amounts shown in Table 3 below.

(part by weight) inner layer material 1stPOP 2ndPOP ZnO CaO Erucamide Example 1 10 35.5 Manufacturing Example 1 2.5 Production example 2 1.0 1.0 Example 7 10 35.5 Production example 3 2.5 Production example 4 1.0 1.0 Example 8 10 35.5 Production example 5 2.5 Production example 6 1.0 1.0 Example 9 10 35.5 Manufacturing Example 1 0.1 Production example 2 0.05 1.0 Example 10 10 35.5 Manufacturing Example 1 0.5 Production example 2 0.3 1.0 Example 11 10 35.5 Manufacturing Example 1 5 Production example 2 2 1.0 Example 12 10 35.5 Manufacturing Example 1 10 Production example 2 5 1.0 Comparative Example 7 10 35.5 Manufacturing Example 1 - Production example 2 - 1.0 Comparative Example 8 10 35.5 Comparative Manufacturing Example 1 2.5 Comparative Manufacturing Example 2 1.0 1.0

[Characteristics Evaluation]

1) Tensile strength (MPa) and elongation (%): Evaluated according to ASTM D638, and the results are shown in Table 4 below.

2) Transparency (%): Evaluated according to ASTM D1746, transmittance at a wavelength of 600 nm was taken, and the results are shown in Table 4 below.

3) Antibacterial property: Antibacterial property was evaluated according to JIS Z 2801:2010, and the results are shown in Table 4 below. In detail, Escherichia coli ATCC 8739 was inoculated into the ^inner layer of the multilayer film at 1.5 I checked the log. At this time, the antibacterial activity value was calculated as log(B/A), where A is the number of bacteria in the multilayer film sample after 24 hours, and B is the number of bacteria in the control group (blank, Stomacher 400 poly-bag) after 24 hours.

4) Anti-fungal property: Anti-fungal property was evaluated according to ASTM G21-15. In detail, five types of mold ( Aspergillus brasiliensis ATCC 9642, Chaetomium globosum ATCC 6205, Penicillium funiculosum ATCC 11797, Trichoderma virens ATCC 9645, Aureobasidium pullulans ATCC 15233) were filmed on a multilayer film for 28 days at 28-30℃ and relative humidity above 85%. was cultured on the inner layer and graded according to the following criteria.

- Level 0: unable to grow

- Grade 1: Grows less than 10% of the area above the specimen.

- Grade 2: Grows from more than 10 area% to less than 30 area% above the specimen.

- Grade 3: Grows from more than 30 area% to less than 60 area% above the specimen.

- Grade 4: Grows over 60% of the area above the specimen.

tensile strength
(㎫) elongation rate
(%) transparency
(%) antibacterial
(log) anti-fungal
(Rating) Example 1 19.2 241 89 4.2 0 Example 7 18.5 240 88 2.6 One Example 8 18.3 238 90 2.3 One Example 9 17.8 226 92 1.2 2 Example 10 18.4 235 90 3.3 0 Example 11 18.9 242 85 4.4 0 Example 12 17.1 223 81 4.8 0 Comparative Example 7 17.4 221 93 (Increased number of bacteria) 3 Comparative Example 8 17.9 225 90 2.1 2

Referring to Tables 3 and 4 above, in Example 1, in which zinc oxide nanoparticles surface-modified with silicone oil of HLB 3 to 8 and calcium oxide were added in an appropriate amount, excellent mechanical strength was maintained while maintaining high transparency of the multilayer film. It was confirmed that antibacterial and antifungal properties could be achieved.

Although the present invention has been described through the above-described specific details and limited examples, this is only provided to facilitate a more general understanding of the present invention, and the present invention is not limited to the above-mentioned examples, and the present invention belongs to Those skilled in the art can make various modifications and variations from this description.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and the scope of the patent claims described below as well as all modifications that are equivalent or equivalent to the scope of this patent claim shall fall within the scope of the spirit of the present invention. .

100: first film 200: second film
110: outer layer 120: middle layer 130: inner layer

Claims (8)

It is a multilayer film manufactured by laminating the first film and the second film,
The first film includes an outer layer including first low-density polyethylene and first medium-density polyethylene; A middle layer comprising a second low-density polyethylene and a first polyolefin plastomer; And an inner layer containing a second polyolefin plastomer,
The second film is a nylon film and is laminated with the outer layer of the first film,
The inner layer of the first film is a second polyolefin plastomer satisfying a density of 0.850 to 0.879 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 55 to 65°C. Containing a multilayer film for liquid food packaging. According to clause 1,
The outer layer of the first film is a first low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.926 g/cm3. A multilayer film for liquid food packaging comprising medium density polyethylene satisfying a density of ~0.940 g/cm3, a melt index of 0.5~5.0 g/10 min (2.16 kg, 190°C), and a softening point of 100~130°C. According to clause 2,
The middle layer of the first film is a second low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.885 g/cm3. For liquid food packaging, comprising a first polyolefin plastomer satisfying a density of ~0.910 g/cm3, a melt index of 0.3~5.0 g/10 min (2.16 kg, 190°C), and a softening point of 70~100°C. Multilayer film. delete a) Co-extrusion method, comprising an outer layer containing a first low-density polyethylene and a medium-density polyethylene, a middle layer containing a second low-density polyethylene and a first polyolefin plastomer, and an inner layer containing a second polyolefin plastomer. Manufacturing a first film; and
b) laminating the outer layer of the first film and the nylon film so that they are in contact with each other,
The inner layer of the first film is a second polyolefin plastomer satisfying a density of 0.850 to 0.879 g/cm3, a melt index of 0.3 to 5.0 g/10 minutes (2.16 kg, 190°C), and a melting point of 55 to 65°C. A method of manufacturing a multilayer film for liquid food packaging, comprising: According to clause 5,
The outer layer of the first film is a first low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.926 g/cm3. A multilayer film for liquid food packaging comprising medium density polyethylene satisfying a density of ~0.940 g/cm3, a melt index of 0.5~5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 100~130°C. Manufacturing method. According to clause 6,
The middle layer of the first film is a second low-density polyethylene satisfying a density of 0.910 to 0.925 g/cm3, a melt index of 0.5 to 5.0 g/10 minutes (2.16 kg, 190°C), and a softening point of 95 to 120°C, and 0.885 g/cm3. Comprising a first polyolefin plastomer (first POP) satisfying a density of ~0.910 g/cm3, a melt index of 0.3~5.0 g/10 min (2.16 kg, 190°C), and a softening point of 70~100°C. , Manufacturing method of multilayer film for liquid food packaging. delete