JPH0729406B2 - Laminated material excellent in aroma retention and container using the laminated material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> In the present invention, a resin layer made of a polyester resin containing a copolymerized polyester modified with an acid component as a main component is laminated on the side of the base material which is in contact with the content. The present invention relates to a laminated material having an excellent aroma retaining property and a container using the laminated material.

<Prior art> Low-density polyethylene (LDPE), polyfluoropyrene (PP) is used as the layer in contact with the contents of the container for packaging liquids such as juice, liquor and mineral water, and the bag for packaging food products such as coffee powder and candy. The polyolefin resin represented by) is widely used.

This polyolefin resin is harmless to the human body, inexpensive, easy to heat seal, and excellent in water resistance and moisture resistance, and is used by laminating it with a base material and an adhesive layer.

However, when laminating the polyolefin resin, the odor peculiar to the polyolefin generated during extrusion does not disappear, and not only does it have a great effect on the taste of liquids and foods, but also the polyolefin resin has the property of easily adsorbing and transmitting aroma components. Therefore, the scent and taste of the contents were significantly reduced.

In order to solve such a problem, it has been proposed to use a copolymerized polyester, which is a resin that produces less odorous components and is less likely to absorb and permeate aroma components, instead of the polyolefin resin. As the copolyester, a polyester produced by polycondensation of terephthalic acid, isophthalic acid and ethylene glycol, for example, 1,4
A polyester produced by polycondensation of a glycol component containing cyclohesane dimethanol and a dibasic acid component.

By using a copolyester, polyethylene terephthalate originally has few volatile substances at the time of heat processing, and by lowering the melting temperature while maintaining low adsorption of aroma components, heat sealing property can be imparted. It is possible.

However, the copolyester generally has no mechanical strength, particularly elongation, is brittle against the stress applied to the packaging material after heat sealing, and it is difficult to form a uniform heat sealing layer. It had a defect that the heat sealing stability was poor.

Further, the extrusion processability is inferior to that of the polyolefin resin, so that it is difficult to form a stable film with an extruder for general polyolefin resin, and it is necessary to use a screw for polyester processing and to reduce the air gap. A device such as shortening was necessary. Therefore, low density polyethylene, ethylene-vinyl acetate copolymer is widely used as the ionomer etc. in the innermost layer of a flexible pouch for packaging quasi-drugs such as medicinal ingredients such as poultices and medicated bath salts. It is used. These resins have excellent heat-sealing properties and also have appropriate mechanical strength.

However, 1-menthol, which is a medicinal component such as a poultice and a medicinal health bath agent, dl-camphor and various fragrances are adsorbed to these resin layers, and by further permeation,
It penetrates into the adhesive layer with the base material to reduce the adhesive force and to lose the function as a packaging bag. Therefore, a packaging bag having a polyacrylonitrile resin as the innermost layer has been proposed for the purpose of preventing adsorption and permeation of a medicinal component into the inner layer resin.

However, the polyacrylonitrile resin easily decomposes at a high temperature, and it is necessary to control the temperature precisely and shorten the residence time of the resin, and it is difficult to process the resin with a general polyolefin extruder. Therefore, it was necessary to make a polyacrylonitrile film by a separate description of a dedicated processing machine and then to bond it to a substrate by a method such as dry lamination.

Furthermore, as a beverage container for juice or the like, in recent years, a container made of paperboard as a base material, provided with a ruled line for processing, and bent from the part of the ruled line has been widely used.

Also, when making a box as a liquid container, there is a process of punching the container material into the mold of the liquid container to make a groove trace of the bent part called a ruled line, and the container material has some flexibility. Elongation is required, but also in this point, the above-mentioned copolymer type polyester is insufficient, and there is a possibility that cracking may occur or floating with the paperboard may occur.

<Problems to be Solved by the Invention> An object of the present invention is to provide a laminated material excellent in aroma retaining property in which the aroma component of the contents is less adsorbed and the aroma and the like of the resin layer is less transferred to the contents. Was to do.

Another object of the present invention is to provide a laminate material having an excellent aroma retaining property, which has a resin layer made of a copolyester having heat sealing property with polyolefin.

Another object of the present invention is to provide a laminated material excellent in aroma retaining property in which a resin layer made of a copolyester is formed by extrusion from an extruder, like the polyolefin resin on the substrate.

Further, it is an object of the present invention to provide a container capable of efficiently storing a content containing an aroma component such as juice using the above laminated material.

<Means for Solving the Problems> The present invention provides terephthalic acid on the side of the base material that is in contact with the content.
It is a laminated material having an excellent aroma retaining property in which a resin layer containing 5 to 30 parts by weight of polyolefin is added to 95 to 70 parts by weight of a copolyester produced from isophthalic acid and ethyl glycol.

Further, the present invention is a laminated material having an excellent aroma retaining property in which the base material is a paperboard provided with a polyolefin layer on the outside, and the same resin layer as described above is laminated on the side in contact with the contents.

Furthermore, the present invention is a bag-shaped container in which the resin layers of the above-mentioned laminated material are heat-sealed.

Furthermore, the present invention provides the aforementioned laminated material with ruled lines,
It is a container formed by bending from this ruled line and heat sealing.

Hereinafter, the present invention will be described in detail.

The base material that is a part of the laminated material of the present invention is not particularly limited, but includes plastics, paper, a laminated body of plastics and metal, a laminated body of plastics and paper, and a paper and metal. Is preferably a laminate of plastics, paper and metal, more specifically, a laminate of biaxially stretched polyethylene terephthalate and aluminum foil, a laminate of paper and aluminum foil, polyethylene and paper. And the like, which are excellent in heat resistance with little thermal deformation when the resin is extruded at 200 ° C. or higher. The film or sheet of the base material may be printed on the front side or the intermediate layer of the base material, which is less necessary.

Next, the polyester-based resin used for the resin layer laminated on the side in contact with the content of the base material is a polyester-based resin obtained by adding a polyolefin containing a copolymerized polyester modified with an acid component as a main component. The copolyester is a polyester produced by polycondensation of terephthalic acid, isophthalic acid and ethylene glycol.

The polyolefin to be added includes polyethylene, polypropylene, linear low density polyethylene and modified products thereof.

By using polyester produced by polycondensation of terephthalic acid, isophthalic acid and ethylene glycol, polyethylene terephthalate resin generally has less resin odor caused by volatile components and heat with low adsorption of aroma components. A polyester that can be sealed can be obtained. Further, in order to obtain a stable sealing property at the time of heat sealing and to obtain a resin layer having a uniform thickness distribution at the time of extruding a resin made of polyester, 30 to 5 parts by weight relative to 70 to 95 parts by weight of the polyester is used. It is necessary to add some polyolefin resin.

When the amount of added polyolefin exceeds 30% by weight,
Although it is possible to obtain stable sealing properties during heat sealing and extrusion processability close to that of polyolefins, the amount of resin odor and aroma components adsorbed due to volatile components increases.

That is, when the amount of the polyolefin added is in the range of 5 to 30 parts by weight, the stable sealing property at the time of heat sealing and the polyolefin can be maintained while suppressing the adsorption amount of the resin odor and the aroma component caused by the volatile component to a level satisfying the above. It is possible to obtain extrudability very close to

The method of laminating the resin layer consisting of the base material and the polyester-based resin is extrusion laminating method using an adhesive, extrusion coating method not using an adhesive, and extruding the adhesive resin and the resin layer in multiple layers by a coextrusion method, There are a method of extrusion coating on a base material and a method of laminating the polyester film prepared in advance with the base material by a method such as dry lamination.

<Function> The resin used in the resin layer described in the present invention has the basic properties of a polyester resin. That is, since less volatile substances are generated from the resin, the scent and taste of the contents hardly change due to the transfer of odor. Further, since the flavor component of the contents is less adsorbed, the scent and taste of the contents can be retained as they are when they are filled.

Generally, polyethylene terephthalate produced from terephthalic acid and ethylene glycol has high crystallinity and a melting point.
Although it is as high as around 255 °, it is produced by replacing part of terephthalic acid, which is a dicarboxylic acid component, with isophthalic acid. Copolyester has a low crystallinity and a melting point of 200.
The temperature becomes below ℃, and the heat sealing property is improved.

However, such a copolyester resin has heat sealability between itself, but it does not have heat sealability with respect to the polyethylene resin that is often used in the outermost layer of the container, which is required due to the box-forming structure of a general fluid container. Was enough.

Therefore, in the present invention, the above-mentioned copolyester resin is used as a basic material, and a polyolefin resin having the same heat-sealing property as or the same as the polyolefin resin is blended.

As a result, the innermost resin layer of the present invention, like the polyolefin, is provided with stable heat-sealing property even at a low temperature from around 120 ° C. and, at the same time, has sufficient heat-sealing with respect to the polyolefin such as the outermost polyethylene. Have sex.

Further, the copolymerized polyester resin is inferior in elongation and flexibility, but by blending with a polyolefin resin, the physical properties are improved, and the box-forming workability of a paper container for forming ruled lines is also improved, and the resin layer is It is less likely to crack or float more than the base paperboard.

<Example 1> Biaxially stretched polyethylene terephthalate film (12μ)
50 mol% each of terephthalic acid and isophthalic acid as dibasic acid components on a base material laminated with aluminum foil (9μ)
A polyester produced by using ethylene glycol as the glycol component, which has a density of 0.
916, resin layer made of polyester resin containing low density polyethylene with melt flow index 23g / 10min (50
μ) was extruded through a two-component reaction type urethane adhesive to obtain a laminated material. The added amount of the low-density polyethylene added was 3, 5, 15, 30, 50 parts by weight with respect to 97, 95, 85, 70, 50 parts by weight of the polyester resin. The resin side made of polyester resin of the obtained laminated material is the side in contact with the contents, and by heat sealing, the part in contact with the contents has a size of 10 cm × 10 cm, and a packaging bag having an area of 200 cm ^2. It was made. Each bag was filled with a poultry material containing 50 ml of 100% fruit juice orange juice and 50 mg of 1-menthol and stored at 25 ° C. Table 1 shows the heat-sealing strength required for producing the packaging bag, the amount of d-limonene in the orange juice adsorbed in the bag after storage for 2 weeks and 1
-Indicated the amount of menthol.

<Comparative Example 1> A polyester resin layer produced by using terephthalic acid and isophthalic acid as dibasic acid components in an amount of 50 mol% each on the same substrate as in Example 1 and using ethylene glycol as a glycol component. (50μ) was extruded through a two-component reactive urethane adhesive. The polyester resin had poorer extrudability than the polyester resin containing the polyolefin component used in Example 1, and it was difficult to obtain a polyester resin layer having a uniform thickness. By using an extruder, a laminated material similar to that of the present invention was obtained. The obtained laminated material was formed into a bag in the same manner as in Example 1 and a storage test was conducted. The test results are shown in Table 1.

Comparative Example 2 A low density polyethylene layer (50 μ) having a density of 0.923 and a melt flow index of 3.7 g / 10 min on the same substrate as in Example 1.
Was extruded through a two-component reactive urethane adhesive to obtain a laminated material of the present invention. The obtained laminated material was formed into a bag in the same manner as in Example 1 and a storage test was conducted. The test results are shown in Table 1.
It was shown to.

As shown in Table 1, in Comparative Example 1 in which the resin layer in contact with the contents was a copolymerized polyester containing no polyolefin, d-limonene in orange juice and 1-menthol in the poultice were not adsorbed. , Heat sealability is inferior.

Comparative Example 2 in which the layer in contact with the content is polyethylene
Then, although the heat sealing property is excellent, d-limonene, 1
-Menthol was adsorbed in the packaging bag. On the other hand, in the example of the present invention, in the copolymerized polyester resin in which the layer in contact with the content contains polyolefin, terephthalic acid, isophthalic acid, and ethylene glycol, low d-limonene and 1-menthol can be obtained. It is a laminated material with a good balance of adsorption and heat sealing properties.

<Example 2> The following laminated member was obtained in which a resin layer made of a polyester-based resin was laminated on the side of the substrate having a polyolefin layer made of low-density polyethylene provided on the outside of the paperboard and in contact with the contents.

(1) Paperboard: Paperboard for milk containers Density 310g / m ² (2) Polyolefin resin layer: Low density polyethylene Density 0.923g / m ² Melt index 3.7g / 10min Resin thickness 20μ (3) Resin layer: (a) Copolymerization To polyester resin (b)
Resin mixed with polyethylene resin. Resin thickness 40μ (a) Copolymerized polyester resin terephthalic acid and isophthalic acid as dicarboxylic acid components
In a proportion of each 50 mole%, copolymerized polyester produced by using ethylene glycol as the diol component (b) polyethylene resin: low-density polyethylene density 0.916 g / cm ² melt index 23g / cm ² (c) mixing ratio polyester For each 97,95,85,70,50 parts by weight of resin, 3,5,15,30,50 parts by weight of polyethylene resin are blended,
Samples 1-5 were obtained.

As a method for laminating the outermost layer polyolefin resin and the innermost resin layer, a melt extrusion coating method on a paperboard is used,
I did.

Comparative Example-3 A liquid container material was obtained by using only the copolyester resin without blending the polyester resin in the innermost layer of (3) in the configuration of Example-1. The resin thickness was the same as 40μ.

<Comparative Example-4> In the configuration of Example-2, the same low-density polyethylene as the olefin resin of the outermost layer was used for the innermost resin layer, and a liquid container material was obtained. The resin thickness was 40 μm and the same.

Incidentally, this structure is almost the same as the structure of a general material for liquid containers such as milk and juice.

<Example-3> Samples 1 to 5 of the material for liquid container obtained in Example-2
And the performance evaluation was performed about the following items about the samples obtained in Comparative Example-3 and Comparative Example-4.

(1) Adsorption of flavor components Prototype liquid container using each sample (for 1000ml capacity)
Fill each container with 1000 ml of 100% orange juice and seal 5
After storing at 4 ° C. for 4 weeks, limonene in orange juice adsorbed on the innermost layer resin of the liquid container was quantitatively measured by gas chromatography after storage.

The amount of limonene adsorbed in the innermost layer of low density polyethylene of Comparative Example-2 was set to 100% and the amount adsorbed for each sample was displayed.

(2) Heat-sealing property between the innermost resin layers The innermost resin layers are stacked on each other and heat-sealed to check the heat-sealing property. Bar sealer used Temperature 130 ℃ -220 ℃ Pressure 3kg / cm ² hours 5 seconds (3 ) Heat-sealing property of innermost resin layer and outermost polyolefin layer Each sample was laminated with the innermost resin layer and polyethylene resin of the outermost layer and heat-sealed, and the heat-sealing conditions were the same as in (2).

(4) Ruled line bending test A ruled line strength tester (manufactured by Resca Co., Ltd.) was used to perform a bending and stretching test of the ruled line portion up to 90 ° 20 times, and then the cracks in the ruled line portion were evaluated. The bending speed during the test was 10 degrees / second. Table 2 shows the performance evaluation of each sample of (1) to (4).

As shown in Table 2 above, the heat-sealing property of the sample having the polyethylene composition of the innermost layer of Comparative Example-4 is good because the innermost layers and the innermost layer / outermost layer are stably heat-sealed even at the low sealing temperature. The amount of limonene adsorbed in the juice was large, and a nasty smell such as polyethylene odor was produced by sensory testing.

Moreover, limonene was not detected in the sample having the innermost-layer copolyester composition of Comparative Example-3, and it is considered that almost no limonene was adsorbed, and there was no offensive odor in sensory inspection, and there was no change in taste or aroma. However, the heat sealing property was inferior. In particular, the outermost layer polyethylene resin and the innermost layer copolyester showed almost no heat-sealing property.

On the other hand, in the sample of the innermost-layer polyethylene-blended copolyester composition of Example-2, limonene was not detected or was at an extremely low level as compared with Comparative Example-3, and a sensory test revealed that no offensive odor or discoloration was observed. There wasn't.

In particular, samples 2 to 4 with a polyethylene content of 5 to 30%
Has a temperature range in which limonene is not detected, and the heat-sealing properties are also good for the innermost layers and for both the innermost layers / outermost layers. In practice, sufficient heat-sealing properties can be obtained by increasing the heat-sealing conditions. Was completed.

In addition, regarding the crack of the ruled line portion at the time of bending, the second embodiment
Samples 2 to 5 were not observed as in Comparative Example 4.

<Effects of the Invention> (1) By using the laminated material of the present invention, it is possible to obtain a container in which a medicinal component and a flavor component of the contents are less adsorbed in the container and odor and the like are less transferred from the container. I can. As a result, it is possible to preserve the taste and aroma of contents that are rich in flavor components such as liquor and juice and are sensitive to odor components transferred from the outside as they are filled. Become.

(2) Since the laminated material of the present invention has the effect of the above (1) and has good heat-sealing property, box-making processability and the like as in the conventional innermost layer polyolefin resin constitution, a box-making machine and contents For the material filling and the like, the conventional method can be used to obtain the required product physical properties.

(3) Further, when the resin layer is formed on the base material, it can be formed by extrusion using a generally used extruder for polyolefin.

Claims (4)

[Claims] 1. A terephthalic acid is provided on the side of the base material which is in contact with the content,
Copolyester produced from isophthalic acid and ethylene glycol 95 to 70 parts by weight of polyolefin to 5 to 30 parts by weight
A layered material with excellent aroma retention in which resin layers mixed in the range of parts by weight are layered. 2. The laminated material having excellent aroma retaining property according to claim 1, wherein the base material is a paperboard having a polyolefin layer provided on the outside. 3. A bag-shaped container in which resin layers of the laminated material according to claim 1 are heat-sealed. 4. A container formed by forming a ruled line on the laminated material according to claim (2), bending it from the ruled line, and heat-sealing it.