JP2024088933A - Laminated film and processed products made by sealing laminated film - Google Patents

Abstract

【assignment】
The present invention aims to provide a laminated film whose sealed portion is resistant to tearing when the laminated film is sealed to form a bag, and to provide a processed product whose weld-cut sealed portion is resistant to tearing even when the laminated film is sealed by weld-cut sealing.
SOLUTION
A laminated film comprising an inner layer (A), an intermediate layer (B), and an outer layer (C), wherein the inner layer (A) and the outer layer (C) are primarily composed of a polyethylene-based resin, and the intermediate layer (B) is primarily composed of a polybutylene terephthalate-based resin, and wherein an adhesive resin layer (D) is interposed between the inner layer (A) and the intermediate layer (B), and between the intermediate layer (B) and the outer layer (C).
[Selected Figure] Figure 1

Description

The present invention relates to a laminated film and a processed product made by sealing the laminated film.

Patent Document 1 describes an invention relating to an odor-barrier co-extruded multilayer film that can be easily processed to prevent deterioration of the contents of food, miscellaneous goods, etc. due to erosion by volatile components from the outside during storage, and a packaging material and packaging container that use this film (Patent Document 1 [0001]).

The examples in Patent Document 1 describe a coextruded multilayer film with a composition of LLDPE/adhesive resin/PBT copolymer/adhesive resin/LLDPE.

Patent Publication No. 2012-11741

Generally, when making bags from laminated film, the sides and bottom of the bag are sealed, but bags made in this way tend to have easily ruptured seals, resulting in the bag breaking.

Therefore, the goal is to provide a film whose seal is less likely to tear when the laminated film is sealed to make a bag.

After extensive research into the above problem, the inventors discovered that in order to make the sealed portion tear-resistant, the sealed portion needs to be stretchable. Specifically, they discovered that by giving the sealed portion the property of stretching (hereinafter sometimes referred to as extensibility), even if stress is applied to the sealed portion, the applied stress can be dispersed, resulting in a bag with a sealed portion that is tear-resistant.

Furthermore, the inventors have investigated a method of making bags using a fusion seal, with the aim of improving production efficiency when sealing laminated films to make bags. However, when sealing laminated films using fusion seal, the sealed portion is more likely to break than when sealing with a hot plate. This is because, while sealing with fusion seal allows for faster sealing, fusion seal requires a shorter sealing time than hot plate seal and the sealing pressure is smaller, so that the laminated films may not be sufficiently fused together. Furthermore, the fusion seal portion where the laminated film is fusion sealed has a smaller fusion area than the hot plate seal portion where a hot plate seal is used, so that the laminated films may not be sufficiently fused together.

Therefore, as a means for solving the above problems of the present invention,
(1) A laminated film comprising an inner layer (A), an intermediate layer (B), and an outer layer (C),
The inner layer (A) and the outer layer (C) each contain a polyethylene resin as a main component,
The intermediate layer (B) is mainly composed of a polybutylene terephthalate resin,
A laminated film, characterized in that an adhesive resin layer (D) is interposed between the inner layer (A) and the intermediate layer (B), and between the intermediate layer (B) and the outer layer (C);
(2) The laminated film according to (1), wherein the adhesive resin layer (D) is mainly composed of a modified ethylene (meth)acrylate-based resin;
(3) The laminated film according to (1), wherein the polyethylene resin has a density of 0.915 to 0.925 g/ ^cm3 ;
(4) The laminate film according to any one of (1) to (3), characterized in that the laminate film has a total thickness of 50 μm or less;
(5) A processed product having a sealed portion formed by sealing the laminated film according to any one of (1) to (4);
(6) The workpiece according to (5), characterized in that the elongation of the seal portion is 100% or more;
(7) The workpiece according to (5) or (6), characterized in that the strength of the seal portion is 1 N/15 mm or more;
(8) The workpiece according to any one of (5) to (7), characterized in that the seal is a melt-cut seal;
(9) The processed product according to any one of (5) to (8) is a bag obtained by making a bag;
(10) The processed product according to any one of (5) to (8) is a deodorizing bag produced by bagging;
The gist of this paper is as follows.

According to the first aspect of the present invention, since the layer containing polybutylene terephthalate resin as a main component is provided, the deodorizing property is excellent.
According to the second invention, sufficient adhesion can be achieved between the intermediate layer (B) mainly composed of a polybutylene terephthalate resin and the inner layer (A) and outer layer (C) mainly composed of a polyethylene resin, and when the laminated film is sealed to form a processed product, the sealed portion has extensibility, making it possible to form a processed product in which the sealed portion is less likely to tear.
According to the third invention, it is possible to obtain a laminated film having anti-blocking properties. In addition, it is possible to obtain a laminated film having flexibility, and when the laminated film is sealed to obtain a processed product, the processed product can be easily handled. Specifically, since the laminated film has flexibility, when the laminated film is made into a bag (preferably an odor-proof bag), it is possible to easily tie the opening of the bag.
According to the fourth invention, when sealing the laminated film to make a processed product, sealing is possible even with a small amount of heat required to melt the laminated film, so that the sealing speed can be increased and production efficiency can be improved. Furthermore, a laminated film with excellent melt-cutting and sealing suitability can be obtained. In addition, since the layer thickness is as thin as 50 μm or less, when the laminated film is made into a bag (preferably an odor-proof bag), the opening of the bag can be easily tied.
According to the fifth aspect of the present invention, a processed product having excellent odor prevention properties and a sealed portion that is difficult to tear can be obtained.
According to the sixth aspect of the present invention, the seal portion has sufficient extensibility, so that the seal portion is unlikely to tear.
According to the seventh aspect of the present invention, the seal portion has sufficient strength, so that the seal portion is unlikely to be broken.
According to the eighth aspect of the present invention, the sealing speed can be increased compared to the hot plate sealing, thereby improving production efficiency. Also, it is easier to respond to changes in the specifications of the workpiece than with the hot plate sealing.
According to the ninth aspect of the present invention, the sealed portion has sufficient extensibility, so that the sealed portion is less likely to tear.
According to the tenth aspect of the present invention, the sealed portion has sufficient extensibility, so that the sealed portion is difficult to tear. In addition, since the bag is made of a laminated film having an intermediate layer (B) mainly composed of a polybutylene terephthalate resin, the odor-proof bag has excellent odor-proofing properties.

1 is a schematic cross-sectional view showing one embodiment of a laminated film according to the present invention. FIG. 2 is a schematic diagram for explaining in detail a method for measuring the elongation and strength of a sealed portion in which the laminated film according to the present invention is sealed. 1A is a schematic perspective view showing a bag made by welding sealing using the laminated film of the present invention, FIG. 1B is a schematic side view, and FIG. 1C is a schematic partial cross-sectional view showing an enlarged view of the sealed portion. 1A is a schematic perspective view showing a bag made by hot plate sealing using the laminated film of the present invention, FIG. 1B is a schematic side view, and FIG. 1C is a schematic partial cross-sectional view showing an enlarged view of the sealed portion. 1A to 1C are schematic plan views showing a method for producing a bag by heat-cutting and sealing a laminated film according to the present invention.

The present invention is described in detail below, but is not limited thereto. Various forms can be adopted within the scope of the present invention, provided that the same effect is achieved, without departing from the spirit of the present invention.

In this specification, the term "main component" means a component that constitutes a layer and accounts for 50% or more by weight, preferably 60% or more by weight, more preferably 80% or more by weight, even more preferably 90% or more by weight, and particularly preferably 95% or more by weight.

In this specification, the term "sealed portion" refers to a sealed portion sealed by melt-cutting sealing, and a sealed portion sealed by hot plate sealing, referred to as a "hot plate sealing portion."

A typical structure of the laminated film of the present invention is an inner layer (A) mainly composed of a polyethylene resin / an adhesive resin layer (D) / an intermediate layer (B) mainly composed of a polybutylene terephthalate resin / an adhesive resin layer (D) / an outer layer (C) mainly composed of a polyethylene resin.

Figure 1 shows a schematic cross-sectional view of the typical configuration described above.

<Inner layer (A)>
The inner layer (A) is mainly composed of a polyethylene resin, which allows the laminated film 1 to have excellent sealing properties.

The density of the polyethylene resin used for the inner layer (A) is not particularly limited, but is preferably 0.880 to 0.930 g/cm ³ , and more preferably 0.915 to 0.925 g/cm ³ .

By making the density 0.915 g/ ^cm3 or more, the crystallinity of the polyethylene resin can be increased, and the laminate film 1 can be made excellent in blocking resistance. In addition, the laminate film 1 can be made excellent in strength, and when the laminate film 1 is sealed to form a processed product, the sealed portion is unlikely to break.

By setting the density to 0.925 g/cm3 or ^less , it is possible to obtain a laminated film 1 that is excellent in flexibility and easy to stretch. As a result, when the laminated film 1 is sealed to form a processed product, the sealed portion can be made to be difficult to tear. In addition, since the laminated film 1 has excellent flexibility, when the laminated film 1 is sealed to form a processed product, the processed product can be made to be easy to handle, and further, when the laminated film 1 is made into a bag (preferably an odor-proof bag), the opening of the bag can be easily tied.

Specific examples of polyethylene resins include ultra-low density polyethylene, low density polyethylene, high density polyethylene, linear low density polyethylene, etc., but it is preferable to use linear low density polyethylene. Linear low density polyethylene has a moderately low melting point, so it can be used to make a laminate film 1 with excellent sealing properties.

In terms of mechanical strength and processability, the melt flow rate (MFR) value of the polyethylene resin at 190°C is preferably 1.0 to 10.0 g/10 min, more preferably 1.0 to 5.0 g/10 min, and particularly preferably 1.0 to 3.0 g/10 min. By setting the MFR value within the above range, it is possible to provide an appropriate melt tension during melt processing. In the present invention, a polybutylene terephthalate resin is used for the intermediate layer (B), but since polybutylene terephthalate resin alone has a high MFR and a fast crystallization rate, which makes it poor in film formability, the film formability of the laminated film 1 can be ensured by using a linear low-density polyethylene with high melt tension for the inner layer (A).

The polyethylene resin may be one type or two or more types. When two or more types are used, the combination and ratio of the resins can be selected as desired depending on the purpose. For example, a blend of linear low-density polyethylene and low-density polyethylene can be exemplified, but those skilled in the art can select a suitable form as appropriate, and there is no particular limitation.

The melting point of the polyethylene resin used for the inner layer (A) is not particularly limited, but is preferably 80 to 135°C, more preferably 90 to 130°C, and particularly preferably 100 to 120°C. By keeping it within the above range, a laminate film 1 with excellent sealing properties can be obtained.

In addition, additives can be added to the inner layer (A) as necessary, and those skilled in the art can add suitable additives as desired.

Furthermore, the inner layer (A) may contain other resins as long as it is mainly composed of a polyethylene resin, and is not particularly limited.

The thickness of the inner layer (A) is not particularly limited, but is preferably 1 to 20 μm, and more preferably 3 to 10 μm. If the inner layer (A) is within the above range, high-speed sealing is possible even when the laminated film 1 is sealed to form a processed product, and the strength of the seal portion formed by sealing the laminated film 1 can be made sufficient.

<Middle Class (B)>
The intermediate layer (B) is mainly composed of a polybutylene terephthalate resin. This allows the laminated film 1 to have excellent odor prevention properties. In addition, when the laminated film 1 is sealed and processed, it can be made into a processed product with excellent odor prevention properties.

The intermediate layer (B) is mainly composed of polybutylene terephthalate resin. The polybutylene terephthalate resin may be of only one type or of two or more types. When two or more types are used, the combination and ratio of the resins may be selected as desired according to the purpose.

Specific examples of polybutylene terephthalate resins include homopolymers and copolymers. Examples of the acid component of the copolymer include, but are not limited to, terephthalic acid, isophthalic acid, and adipic acid.

The thickness of the intermediate layer (B) is not particularly limited as long as it can provide odor-preventing properties to the laminated film 1, but it is preferably 1 μm to 10 μm. In addition, the thickness of the intermediate layer (B) is sufficient to exhibit odor-preventing properties if it is 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, or 6 μm or more.

In addition, additives can be added to the intermediate layer (B) as necessary, and those skilled in the art can add suitable additives as desired.

Furthermore, as long as the intermediate layer (B) is mainly composed of polybutylene terephthalate resin, it may contain other resins and is not particularly limited.

<Outer layer (C)>
The outer layer (C) can be the same as that described in the section on inner layer (A). By using the same resin for the inner layer (A) and the outer layer (C), the laminated film can be used without worrying about the front and back. In addition, the laminated film can be made less prone to curling.

<Adhesive Resin Layer (D)>
As shown in the representative structure described above, the adhesive resin layer (D) is located between the inner layer (A) and the intermediate layer (B), and between the intermediate layer (B) and the outer layer (C).

The adhesive resin layer (D) is preferably composed mainly of a modified ethylene (meth)acrylate resin. By using a modified ethylene (meth)acrylate resin as the main component, the layers of the laminated film 1 can be sufficiently bonded together, and in particular, the intermediate layer (B) composed mainly of a polybutylene terephthalate resin can be sufficiently bonded together with the inner layer (A) and outer layer (C) composed mainly of a polyethylene resin.

In addition, by using a modified ethylene (meth)acrylate resin in the adhesive resin layer (D), a laminated film 1 with excellent extensibility can be obtained. Furthermore, when a laminated film 1 using a modified ethylene (meth)acrylate resin as the adhesive resin layer (D) is sealed, the sealed portion has extensibility, so that the sealed portion is less likely to tear, making it possible to produce a processed product.

Modified ethylene (meth)acrylate resins are ethylene (meth)acrylate resins modified with unsaturated carboxylic acids, their anhydrides, or derivatives.

Examples of unsaturated carboxylic acids to be modified include, but are not limited to, unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, furanic acid, crotonic acid, vinyl acetate, and pentenoic acid, and α,β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid, or their anhydrides and derivatives. Of these, α,β-unsaturated dicarboxylic acids or their anhydrides and derivatives are preferred, and it is even more preferred to use maleic anhydride. Maleic anhydride can adequately bond each layer together due to the covalent bonds between molecular chains generated by the thermal reaction, and when the laminated film 1 is sealed, the sealed portion has extensibility, making it possible to produce a processed product in which the sealed portion is less likely to tear.

In addition, additives can be added to the adhesive resin layer (D) as necessary, and those skilled in the art can add suitable additives as desired.

Furthermore, the adhesive resin layer (D) may contain a resin other than the adhesive resin, and is not particularly limited. For example, the adhesive resin layer (D) can be a blend of an adhesive resin and a polybutylene terephthalate resin.

<Laminated film 1>
The total thickness of the laminated film 1 is preferably from 1 to 50 μm, more preferably from 5 to 30 μm, and particularly preferably from 10 to 25 μm.
By setting the thickness within the above range, the laminate film 1 can be made soft and easy to handle by reducing the thickness while providing appropriate stiffness and strength to the laminate film 1. Furthermore, when the thickness is within the above range, the laminate film 1 can be sealed to form a processed product even if the amount of heat required to melt the laminate film 1 is small. This allows for a high-speed sealing, improving production efficiency. Furthermore, when the laminate film 1 is made into a bag to form an odor-proof bag, the opening of the odor-proof bag can be easily tied.

The laminated film 1 of the present invention is not limited to the above-mentioned typical configuration, and layers other than the inner layer (A), intermediate layer (B), outer layer (C), and adhesive resin layer (D) can be provided as necessary.

As shown in the representative configuration above, by making the layers symmetrical in the thickness direction, it is possible to make the laminate film 1 less prone to curling.

<Processed products>
By sealing the laminated film of the present invention, a processed product having a sealed portion can be obtained.

The laminated film of the present invention has excellent elongation. Therefore, even when the laminated film is sealed to provide a sealed portion, it is possible to obtain a processed product that has excellent elongation and is resistant to tearing. Furthermore, because of its excellent elongation, when the laminated film is sealed to form a bag, it is possible to obtain a processed product in which the sealed portion is resistant to tearing. Specifically, even if stress is applied to the sealed portion, the applied stress can be dispersed, and a bag can be obtained in which the sealed portion is resistant to tearing.

The processed product obtained by the present invention has a sealed portion, but the sealed portion has sufficient extensibility and strength, making it difficult for the sealed portion to tear.

Specifically, it is preferable that the elongation of the sealed portion is 100% or more, 120% or more, 140% or more, 160% or more, 180% or more, or 200% or more. By stretching the sealed portion, it is possible to produce a processed product in which the sealed portion is resistant to tearing. Furthermore, when the laminated film is sealed to produce a bag, it is possible to produce a bag in which the sealed portion is resistant to tearing. There is no particular upper limit to the elongation of the sealed portion.

Figure 2 is a schematic diagram for explaining in detail how to measure the elongation and strength of the sealed portion of the laminated film according to the present invention.

The method for measuring the elongation of the seal portion will be described in detail below with reference to FIG.
(1) The laminated film 1 is sealed to produce a processed product having a sealed portion.
(2) A rectangular test piece 4 (width 15 mm) is prepared from the workpiece having a seal portion. At this time, the test piece is prepared so that the seal portion 3 is positioned in the center in the longitudinal direction of the test piece, as shown in FIG.
(3) The test piece 4 is attached to a tensile tester with a chuck distance of 40 mm.
(4) The tensile test is performed at a speed of 500 mm/min in the tensile direction shown in FIG. 2 until the seal portion 3 breaks.
(5) Calculate the elongation (%) of the seal portion. The calculation method is as follows:
Elongation (%)=([chuck distance at break]−[chuck distance before tensile test (40 mm)])/[chuck distance before tensile test (40 mm)]×100.

The strength of the sealed portion is preferably 1N/15mm or more, 3N/15mm or more, 5N/15mm or more, 6N/15mm or more, 7N/15mm or more, 9N/15mm or more, or 11N/15mm or more. When the strength of the sealed portion is within the above range, the sealed portion can be made into a processed product that is difficult to tear. Furthermore, when the laminated film is sealed to make a bag, the sealed portion can be made into a bag that is difficult to tear. There is no particular upper limit to the strength of the sealed portion. There is also a correlation between the elongation and strength of the sealed portion, and if the sealed portion has elongation, the strength of the sealed portion tends to increase.

The method for measuring the strength of the seal portion will be described in detail below with reference to FIG.
(1) The laminated film 1 is sealed to produce a processed product having a sealed portion.
(2) A rectangular test piece 4 (width 15 mm) is prepared from the workpiece having a seal portion. At this time, the test piece is prepared so that the seal portion 3 is positioned in the center of the length direction of the test piece, as shown in FIG.
(3) The test piece 4 is attached to a tensile tester with a chuck distance of 40 mm.
(4) The tensile test speed is set to 500 mm/min, and the tensile test is performed in the tensile direction shown in FIG. 2 until the seal portion 3 breaks.
(5) The strength of the seal (N/15 mm) is the maximum load at which the seal breaks.

The laminated film of the present invention also has an intermediate layer (B) mainly composed of a polybutylene terephthalate resin, and therefore has excellent deodorizing properties. Therefore, when the laminated film of the present invention is sealed to produce a processed product, a processed product with excellent deodorizing properties can be obtained.

As for the processed product, for example, a laminated film can be sealed to make a bag. In addition, the bag made by the present invention has odor-proofing properties and can be used as an odor-proof bag.

The odor-proof bag obtained by the present invention can contain odorous substances and can seal the odor of the odorous substances inside the odor-proof bag. Examples of odorous substances include human or animal excrement, used diapers, food waste, etc. Also examples include foods with strong odors such as kimchi and natto.
Furthermore, contents that are prone to absorbing odors can be stored in the odor-proof bag, and the contents can be protected from odors outside the bag. For example, when storing the contents in a location close to items that contain volatile chemical components such as insect repellents, deodorants, and fragrances, the contents can be stored in the odor-proof bag to protect them from the volatile chemical components.
As described above, the contents to be contained in the odor-proof bag and the method of using the odor-proof bag are not particularly limited, and those skilled in the art can select a suitable form.

The laminated film can also be sealed to process it into gloves. In this way, the shape of the processed product can be determined by those skilled in the art as appropriate and is not particularly limited.

Specific sealing methods include fusion sealing, hot plate sealing, ultrasonic sealing, and high frequency sealing, among which fusion sealing and hot plate sealing are preferably used.

The laminated film of the present invention has excellent suitability for melt-cut sealing because the laminated films can be sufficiently fused together even when sealed at high speed. Furthermore, melt-cut sealing is easier to adapt to changes in the specifications of the processed products than other sealing methods, so by using the laminated film of the present invention for melt-cut sealing, production efficiency can be improved.

Figure 3 shows a schematic perspective view (A) of a bag produced by melt-cutting and sealing using the laminated film according to the present invention, a schematic cross-sectional view (B), and a schematic partial side view (C) showing an enlarged view of the sealed portion.

As shown in the schematic perspective view (A) of FIG. 3, the laminated film 1 can be made into a bag by melt-sealing the sides and bottom of the bag to form the melt-sealed portion 31. It is also possible to make a bag by folding a sheet of laminated film 1, making the crease the bottom of the bag, and melt-sealing the parts that will become the sides of the bag.

The method for making bags by melt-cutting and sealing can be any conventional method known in the art and is not particularly limited.

Figure 4 shows a schematic perspective view (A), a schematic side view (B), and a schematic partial cross-sectional view (C) of a bag made by hot plate sealing using the laminated film according to the present invention.

As shown in the schematic perspective view (A) of Figure 4, the laminated film can be made into a bag by sealing the sides and bottom of the bag with a hot plate to form a hot plate sealed portion 32. It is also possible to make a bag by folding a sheet of laminated film, using the crease as the bottom of the bag, and sealing the parts that will become the sides of the bag with a hot plate.

The method for making bags using hot plate sealing can be any conventional method known in the art and is not particularly limited.

Although the above describes the method of making bags from laminated film by melt-cutting or hot plate sealing, any conventionally known method can be used for the bag making method, and those skilled in the art can select a suitable form. For example, the bottom of the bag can be sealed with a hot plate, and the sides of the bag can be melt-cut and sealed, and then the bag can be made using melt-cut sealing and hot plate sealing.

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

<Examples 1 to 2, Comparative Examples 1 to 6>
Using the resins listed below, a laminated film having a structure of inner layer (A)/adhesive resin layer (D)/middle layer (B)/adhesive resin layer (D)/outer layer (C) was obtained by co-extrusion. The thickness of each layer is shown in Table 1.
<Inner layer (A) and outer layer (C)>
・Linear low density polyethylene (LLDPE)
Density: 0.923 g/cm ³ , Melting point: 118°C, MFR: 1.5 g/10 min (190°C)
<Intermediate layer (B)>
・Polybutylene terephthalate (PBT)
Homopolymer, density: 1.310 g/cm ³ , melting point: 223° C., MFR=5 g/10 min
<Adhesive Resin Layer (D)>
Maleic acid modified ethylene (meth)acrylate Density: 0.93 g/cm ³ , Melting point: 92° C., MFR: 1.6 g/10 min
Acid-modified ethylene-butene copolymer Density: 0.90 g/cm ³ , Melting point: 120°C, MFR: 3.5 g/10 min
・Acid-modified LLDPE (1)
Density: 0.90 g/cm ³ , melting point: 119° C., MFR: 1 g/10 min
・Acid-modified LLDPE (2)
Density: 0.907 g/cm ³ , MFR: 2.3 g/10 min
・Acid-modified LLDPE (3)
Density: 0.914 g/cm ³ , MFR: 6.5 g/10 min

<<Stretchability and strength of laminated film>>
The elongation and strength of the obtained laminated film were evaluated. Specifically, the elongation and strength of the laminated film in the MD direction and TD direction were measured. The measurement method was performed with reference to JIS K 7127 (1989), and the measured value was the average of five samples excluding the maximum and minimum values of seven samples. The chuck distance was 80 mm, and the tensile test speed was 500 mm/min. The measurement results are shown in Table 1.

The resulting laminated film was then heat-sealed to produce a workpiece with a heat-sealed portion. The heat-sealing method is described below.

[Fusing seal]
The obtained laminated film was heat-cut and sealed to produce a bag by the following method. The specific production method will be described in detail below with reference to Fig. 5. Fig. 5 is a schematic plan view showing the production method of producing a bag by heat-cutting and sealing the laminated film according to the present invention.
(i) A laminate film 1 is prepared.
(ii) The laminated film 1 is folded along the center in the width direction to produce a laminated film 1' having a crease 5.
(iii) The laminated film 1' having the fold 5 is fusion-cut and sealed using a fusion-cutting and sealing device 6 to produce the bag 7. At this time, the laminated film 1' having the fold 5 in a direction perpendicular to the conveying direction shown in Fig. 5 is fusion-cut and sealed to produce the bag 7. In this way, the bottom of the bag 7 is formed by the fold 5, and the sides of the bag 7 are formed by the fusion-cut and sealed portions 31, making it possible to produce the bag 7.
The sealing temperature of the welding sealing device 6 in the welding sealing machine was 300° C., the contact time between the welding sealing device 6 and the laminated film 1′ having the fold 5 was 0.1 seconds, and the conditions were such that 45 bags could be produced per minute.

[Seal stretch]
The elongation of the weld-sealed portion of the bag produced by the weld-sealing method was measured. Since the produced bag had two weld-sealed portions (see FIG. 5 (iii)), the elongation of the two weld-sealed portions (portions P and Q) was measured. The measurement results are shown in Table 1.
The method for measuring the elongation of the seal portion will be described in detail below with reference to FIG.
(1) A rectangular test piece 4 (15 mm wide) is prepared from a workpiece or bag having a sealed portion. At this time, the test piece is prepared so that the sealed portion is located in the center of the length of the test piece, as shown in FIG.
(2) The test piece 4 is attached to a tensile tester with a chuck distance of 40 mm.
(3) The tensile test speed is set to 500 mm/min, and the tensile test is performed in the tensile direction shown in FIG. 2 until the seal portion 3 breaks.
(4) Calculate the elongation (%) of the seal portion at the time of breakage. The calculation method is as follows:
Elongation (%)=([chuck distance at break]−[chuck distance before tensile test (40 mm)])/[chuck distance before tensile test (40 mm)]×100.

[Seal strength]
The strength of the welded seal part of the bag produced by the welded seal was measured. Since the produced bag had two welded seal parts, the strength of the two welded seal parts (parts P and Q) was measured. The evaluation results are shown in Table 1. The method for measuring the strength of the sealed part is explained in detail below with reference to FIG. 2. (1) A rectangular test piece 4 (width 15 mm) is produced from a workpiece or bag having a sealed part. At this time, the test piece is produced so that the sealed part is located in the center of the length of the test piece as shown in FIG. 2.
(2) The test piece 4 is attached to a tensile tester with a chuck distance of 40 mm.
(3) The tensile test speed is set to 500 mm/min, and the tensile test is performed in the tensile direction shown in FIG. 2 until the seal portion 3 breaks.
(4) The strength of the seal (N/15 mm) is the maximum load until the seal breaks.

<Seal tear evaluation>
The tear resistance of the welded seal part of the bag made by the welded seal was evaluated. As shown in Fig. 3(B), the welded seal part was placed in the center, and a point 1 cm away from the welded seal part (d in Fig. 3(B)) was grabbed by hand and pulled in the pulling direction shown in the figure to evaluate the tear resistance of the welded seal part. Note that in Fig. 3(B), there are two pulling directions, but the bag was pulled in both directions at the same time. The evaluation criteria are as follows.
◯: When pulled in the tensile direction, it does not break immediately, and the melt-cut sealed portion stretches in the tensile direction.
×: When pulled in the tensile direction, the melt-cut sealed portion immediately breaks.
The evaluation results are shown in Table 1.

Deodorization evaluation
First, the obtained laminated film was sealed to produce a bag. The specific bag-making method was to fold the obtained laminated film in half so that the crease would become the bottom of the bag. Then, the side of the bag was sealed using a sealing machine described below to produce the bag.
Sealing machine: P-300 manufactured by Fuji Impulse Co., Ltd. (product number: H6196259/01301D), adhesive temperature: 180°C
Next, the following odor prevention evaluation was performed to confirm the odor prevention performance of the prepared bag. First, 10 g of kimchi was placed in the prepared bag, and the opening of the bag was tied. Then, the bag containing the kimchi was placed in an aluminum pouch with a zipper for 24 hours. After 24 hours, the aluminum pouch was opened and the odor was confirmed. The evaluation criteria were as follows.
A: I didn't notice any smell.
×: A strong odor was detected.
The evaluation results are shown in Table 1.

From Table 1, it can be seen that in Examples 1-2 and Comparative Example 6, the elongation of the sealed portion is 100% or more, and that they have sufficient elongation compared to Comparative Examples 1-5. Furthermore, in Examples 1-2 and Comparative Example 6, the "sealed portion tear evaluation" was all rated "Good," and it can be seen that when the elongation of the sealed portion is 100% or more, the sealed portion is less likely to tear.

Furthermore, Table 1 shows that the adhesive resin layer (D) containing acid-modified ethylene (meth)acrylate as the resin component has better elongation and strength in the sealed portion than adhesive resin layers (D) containing acid-modified ethylene-butene copolymer or acid-modified LLDPE as the resin component, and the "sealed portion tear evaluation" is "Good."

It can also be seen that the elongation and strength of the seal part are related, and that the seal part has sufficient strength when it is elongated. Specifically, in Examples 1-2 and Comparative Example 6, where the seal part has an elongation of 100% or more, the seal part has a strength of 6 N/15 mm or more, which is higher than Comparative Examples 1-5. Furthermore, in Examples 1-2 and Comparative Example 6, the "seal part tear evaluation" was all rated "good," indicating that the seal part is less likely to tear when its strength is 6 N/15 mm or more.

In other words, even when bags are made using heat-cut sealing in Examples 1 and 2, the sealed portion has sufficient elongation and strength, making it suitable for heat-cut sealing.

In addition, Examples 1 and 2 and Comparative Examples 1 to 5, in which the intermediate layer (B) was PBT, were all rated as "good" for odor prevention, demonstrating that they have better odor prevention properties than Comparative Example 6, in which the intermediate layer (B) was 6-66 copolymerized Ny.

1 Laminated film (A) Inner layer (A)
(B) Middle layer (B)
(C) Outer layer (C)
(D) Adhesive resin layer (D)
1' Laminated film with fold 2 Workpiece 3 Sealing section 31 Welding sealing section 32 Hot plate sealing section 4 Test piece 5 Fold 6 Welding sealing device 7 Bag

Claims (10)

A laminated film comprising an inner layer (A), an intermediate layer (B), and an outer layer (C),
The inner layer (A) and the outer layer (C) each contain a polyethylene resin as a main component,
The intermediate layer (B) is mainly composed of a polybutylene terephthalate resin,
A laminated film, characterized in that the inner layer (A) and the intermediate layer (B), and the intermediate layer (B) and the outer layer (C) are laminated together via an adhesive resin layer (D). The laminated film according to claim 1, characterized in that the adhesive resin layer (D) is mainly composed of a modified ethylene (meth)acrylate resin. 2. The laminated film according to claim 1, wherein the polyethylene resin has a density of 0.915 to 0.925 g/cm ³ . The laminated film according to claim 1, characterized in that the laminated film has a total thickness of 50 μm or less. A processed product having a sealed portion formed by sealing the laminated film according to claims 1 to 4. The workpiece according to claim 5, characterized in that the elongation of the seal portion is 100% or more. The workpiece according to claim 5, characterized in that the strength of the seal portion is 1N/15mm or more. The workpiece according to claim 5, characterized in that the seal is a melt-cut seal. The processed product described in claim 5 is a bag that has been made into a bag. The processed product according to claim 5 is a deodorizing bag produced by bagging.

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