JP2020163695A - Laminate for packaging - Google Patents

Abstract

To provide a laminate for packaging capable of maintaining block property and whiteness degree when being formed into a packaging bag.SOLUTION: There is provided a laminate 1A for packaging comprising at least: a base material 6; a white print layer 4 formed on the base material 6; and a sealant layer 2 including a light shielding layer, which are laminated. A whiteness degree of the sealant layer 2 on a white print layer 4 side has an L* value indicated by a L*a*b* colorimetric system of 45 or greater and 65 or smaller, and a whiteness degree of the laminate 1A for packaging on an opposite plane of the sealant layer 2 has an L* value indicated by the L*a*b* colorimetric system of 70 or greater, and has light transmittance in a range of wavelength 200-800 nm of 30% or smaller.SELECTED DRAWING: Figure 2

Description

The present invention relates to laminates and packages.

Conventionally, various packaging bags for packaging food are known. In such a packaging bag, a light-shielding property that protects the contents contained in the packaging bag from external light, a gas barrier property that reduces the influence of gas passing through the packaging bag, and the like are required. Conventionally, an aluminum-deposited film or an aluminum-laminated packaging laminate has been used for such a packaging bag. In addition, the surface (outer surface) of the packaging bag is often decorated by printing or the like.
In recent years, a packaging laminate constructed without using a metal such as aluminum has been known for the purpose of reducing the environmental load at the time of disposal of the packaging bag and for use in a microwave oven (for example, Patent Document 1). , 2). Patent Document 1 discloses a packaging laminate having a design as a packaging material while maintaining a high light-shielding property by including a chromatic color printing layer as well as a white printing in the printing layer.

Further, in Patent Document 2, a black or chromatic resin layer to which a colorant such as a dye or a pigment is added in order to give the sealant layer a light-shielding property and a whiteness, and a white resin layer are used to impart the light-shielding property. The packaging laminate is disclosed.

Japanese Patent No. 3959605 Japanese Patent No. 4915032

However, when printing a chromatic color layer in combination with white printing, which is a technique described in Patent Document 1, white ink, which can originally have a high degree of whiteness, overlaps with the chromatic color layer, and the printing interface is mixed. There is a problem that the original whiteness of the white ink cannot be fully exhibited.
Furthermore, since the white print layer and the chromatic color layer are in close contact with each other, the color of the chromatic color layer is more directly reflected on the surface (outer surface) of the packaging bag.

Further, when the sealant is provided with a light-shielding property as described in Cited Document 2, the pigment of the content may penetrate to the white resin layer depending on the content, and the whiteness may be lowered.

Therefore, an object of the present invention is to provide a packaging laminate capable of maintaining light-shielding property and whiteness when made into a packaging bag.

The first aspect of the present invention is a packaging laminate in which a base material, a white printing layer formed on the base material, and a sealant layer including a light-shielding layer are laminated at least, and the sealant layer The whiteness on the white printing layer side has an L * value of 45 or more and 65 or less according to the L * a * b * color system, and the whiteness of the packaging laminate on the opposite surface to the sealant layer is L * a * b. A laminated body for packaging having an L * value of 70 or more according to a color system and a light transmittance of 30% or less in a wavelength range of 200 to 800 nm.
The white print layer may be laminated on the sealant layer side of the base material.

The titanium oxide content of the white ink used in the white printing layer may be 0.5% to 30%, and the thickness of the white printing layer may be 0.5 μm or more and 2 μm or less.

According to the present invention, the whiteness of the sealant layer on the white printing layer side is such that the L * value according to the L * a * b * color system is 45 or more and 65 or less, and the laminate for packaging on the opposite surface to the sealant layer. By setting the whiteness to an L * value of 70 or more according to the L * a * b * color system and a light transmittance of 30% or less in the wavelength range of 200 to 800 nm, the light-shielding property when made into a packaging bag is obtained. , Whiteness and can be maintained.

It is a top view of the packaging bag which concerns on the packaging laminate of this invention. It is a schematic diagram which shows the laminated structure of the laminated body for packaging of this invention. It is a schematic diagram which shows another laminated structure of the laminated body for packaging of this invention.

An embodiment of the present invention will be described.
The packaging bag 1 of the present embodiment shown in FIG. 1 is a packaging bag that is supposed to contain the contents and can be applied to various sterilizations such as boil sterilization and retort sterilization. The packaging bag 1 of the present embodiment is formed by integrally joining the side portions and the bottom portions of two laminated bodies 1A arranged so as to face each other in the thickness direction by heat sealing.
An opening T is formed at the upper end of the packaging bag 1, and a heat-sealing opening 1d capable of heat-sealing is formed on the inner peripheral surface of the opening T. An internal space S communicating from the opening T to the lower end of each laminated body 1A is formed inside the packaging bag 1.
The laminated body 1A is the laminated body of the present embodiment and has a light-shielding property. The laminated body 1A is configured so that the light transmittance is 30% or less with respect to light having a wavelength in the range of 200 nm or more and 800 nm or less. The light transmittance in the laminated body 1A can be measured using a spectrophotometer. When the light transmittance is 30% or more, the contents may be discolored or the flavor may be deteriorated due to the influence of external light when the product is displayed, so it is preferably 30% or less.

The whiteness of the surface (outer surface) of the packaging bag when the laminate 1A is used as the packaging bag has an L * value of 70 or more according to the L * a * b * color system.
The laminate 1A is a packaging laminate invented for the purpose of packaging bags for food, and if the whiteness L * value of the surface (outer surface) of the packaging bag is 70 or less, the entire pattern is printed when the pattern is printed. It is possible to express the original color of printing without sinking the color of.

FIG. 2 is a diagram schematically showing the layer structure of the laminated body 1A. As shown in FIG. 2, the laminate 1A includes a sealant layer 2, an intermediate resin layer 3, a white printing layer 4, a barrier layer 5, and a base material layer 6.

The sealant layer 2 contains polyolefin as a base polymer. Examples of the polyolefin include homopolyolefins and olefin copolymers, and olefin copolymers are preferable.
Examples of the homopolyolefin include homopolyethylene and homopolypropylene. Examples of the olefin include ethylene, propylene, butene, hexene, α-olefin and the like. Examples of the α-olefin include 1-butene and 1-hexene.

The olefin copolymer may be a block copolymer, a random copolymer, or a mixture thereof. Examples of the olefin copolymer include an ethylene copolymer and the like.
Examples of the ethylene copolymer include a propylene-ethylene copolymer and an ethylene-α-olefin copolymer.

In addition to the function of sealing the packaging bag, the sealant layer 2 of the present invention also has a role of a layer that absorbs light in order to reduce the light transmission of the packaging bag 1. Therefore, the sealant layer contains the above-mentioned base polymer and a light-shielding substance dispersed in the base polymer.

As the light-shielding substance contained in the sealant layer 2, for example, titanium oxide can be selected.

Further, the light-shielding substance contained in the sealant layer 2 may contain a substance other than the above-mentioned titanium oxide, and the color is not particularly limited. For example, it can be considered as a pigment in which carbon black, iron oxide, titanium yellow, an azo dye, a phthalocyanine pigment, or the like is mixed and blended. In particular, the addition of a light-shielding substance such as carbon black or iron oxide, which has a dark color, can be expected to further improve the light-shielding property.

The layer structure of the sealant layer 2 may be a single layer structure or a multi-layer structure. In the case of a multi-layer structure, it is preferable to add the light-shielding substance to the layer on the white printing side rather than the layer in contact with the contents in order to prevent the light-shielding substance from flowing out.

The sealant layer 2 preferably has a whiteness L * value of 45 or more and 65 or less measured from the white printing side. If it is 45 or less, the light-shielding property is sufficient, but the white print layer cannot compensate for the low brightness of the sealant layer 2 in terms of appearance design. If it is 65 or more, the packaging bag is excellent in design, but it cannot maintain sufficient light-shielding property and is not suitable as a packaging bag for storing food.
Furthermore, when the contents are contained in the packaging bag 1 and heat sterilized, if the contents contain a dye, the dye permeates the sealant layer 2 by heating and the surface (outer surface) of the packaging bag 1 It may be transparent to. At that time, if the whiteness of the sealant layer 2 on the white printing side is 65 or more, the pigment of the contents transmitted through the sealant may be conspicuous up to the surface (outer surface) of the packaging bag 1 and the design property may be impaired.

In the present embodiment, the method for producing the sealant film is preferably an inflation method or a casting method, but the method is not limited thereto, and the sealant film may be produced by various known methods.

The role of the white printing layer 4 is to improve the brightness of the entire packaging bag. Since the sealant layer 2 is chromatic, if the white print layer is not formed, the brightness is too low for a food packaging bag, which affects consumers' purchasing motivation, which is not preferable as a packaging bag.
By forming the white printing layer 4, the brightness of the entire packaging bag is improved, and the brightness is not inferior to that of other food packaging bags, and a preferable color as a food packaging bag can be expressed.
In order to satisfy the above brightness, the thickness of the white print layer 4 is preferably 0.5 μm or more and 2 μm or less.
If it is 0.5 μm or less, the brightness of the surface (outer surface) of the packaging bag is too low for food packaging, which is not preferable in terms of design. If it is 2 μm or more, the brightness as a packaging bag is sufficiently maintained, but the cohesive force of the ink is lowered, the strength of the entire printing layer is lowered, and the function as a packaging bag cannot be sufficiently performed.

The material of the white printing layer 4 includes, for example, titanium oxide as the white ink. The titanium oxide content of the white ink used in the white printing layer 4 is 0.5% to 30%, preferably 0.5 to 20%, and particularly preferably 0.5 to 10%.

The white printing layer 4 may be provided between the base material 6 and the sealant layer 2, or may be provided on the base material 6 on the opposite side of the sealant layer 2. In particular, by providing it between the base material 6 and the sealant layer 2, the durability of the white printing layer against the retort treatment can be imparted.

The intermediate resin layer 3 is a resin layer arranged between the sealant layer 2 and the barrier layer 5. The intermediate resin layer 3 is made of, for example, stretched nylon in order to have strength. The intermediate resin layer 3 imparts piercing resistance to the packaging bag 1.
It is not essential that the packaging bag of the present invention is provided with the intermediate resin layer 3, and the intermediate resin layer 3 may not be provided.

The barrier layer 5 is a layer having a gas barrier property that reduces the permeability of a predetermined gas of interest, such as water (water vapor) and oxygen. In the packaging bag of the present invention, the specific configuration of the barrier layer 5 is not particularly limited. For example, the barrier layer 5 may have a metal oxide layer formed by depositing a metal oxide. Examples of metal oxides include silica and alumina. The barrier layer 5 having a metal oxide layer can obtain sufficient gas barrier properties while suppressing the environmental load at the time of disposal to be lower than that of a barrier layer using an unoxidized metal such as aluminum. A barrier film having a layer that exerts a barrier function on a plastic base material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), stretched nylon (ONY), and stretched polypropylene (OPP) may be used as the barrier layer 5. it can.
Regarding the barrier layer 5, a coating layer may be further provided on the metal oxide layer to enhance the gas barrier property. Examples of the structure of the coating layer include a water-soluble polymer film such as polyvinyl alcohol (PVA) and an organic-inorganic hybrid film containing a water-soluble polymer film and an oxide such as silicon or aluminum.

The barrier layer 5 may be provided on the base material 6 on the side of the sealant layer 2, or may be provided on the base material 6 on the side opposite to the sealant layer 2. In particular, by providing it between the base material 6 and the sealant layer 2, the durability of the barrier layer against the retort treatment can be provided. Further, as shown in FIG. 3, when the barrier layer 5 is provided on the base material 6 on the opposite side of the sealant layer 2, the white printing layer 4 is provided so as to be in contact with the barrier layer, so that the barrier layer 5 for retort treatment can be provided. It can be made durable.

The type of the base material layer 6 is not particularly limited. For example, plastic base materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), stretched nylon (ONY), and stretched polypropylene (OPP) can be mentioned. From the viewpoint of heat sterilization treatment, it is preferable to use polyethylene terephthalate (PET).

The sealant layer 2, the intermediate resin layer 3, and the base material layer 6 may be bonded to each other via an adhesive layer. As the bonding method, a known method such as dry lamination can be used. In particular, a dry laminate using a two-component curable urethane adhesive is preferable from the viewpoint of durability against retort treatment and the like.

Further, a pattern layer on which characters, figures, etc. are printed may be provided. Since it is necessary to be visible when the packaging bag is made, the pattern layer needs to be located on the outer layer side of the packaging bag on the opposite surface to the sealant layer than the white printing layer 4. For example, when the white printing layer 4 is provided between the base material 6 and the sealant layer 2, a pattern layer may be provided between the white printing layer and the base material layer 6, and the white printing layer 4 is on the opposite side of the sealant layer 2. When it is provided on the base material 6, the pattern layer may be provided on the white print on the opposite side of the base material 6.

Hereinafter, the laminate and the packaging bag of the present invention will be further described with reference to specific examples, but the present invention is not limited to the contents of the following examples.

(Example 1)
(Preparation of sealant film)
92.0% by weight of the propylene-ethylene block copolymer, 8.0% by weight of the ethylene-α-olefin copolymer, and carbon black and titanium oxide as pigments were premixed in an arbitrary ratio by dry blending. The obtained premix was kneaded at 200 to 230 ° C. using a continuous kneading extruder and pelletized to obtain pellet 1.

Pellets 1 were put into an extruder and heated to 220 ° C. The sealant film of Example 1 was produced by extrusion inflation molding using an inflation device. The thickness of the sealant film was 60 μm. The obtained sealant film was a gray sealant having an L * value of 50 measured from the side to be bonded to the intermediate layer described later.

(Preparation of laminate)
Polyethylene terephthalate (PET) was used as the base material layer. A white ink having a titanium oxide solid content of 7% was formed on the base material layer using a gravure printing machine so as to have a thickness of 1.5 μm. An ONY film having a thickness of 15 μm was used as the intermediate resin layer.
The laminate of Example 1 was prepared by laminating the base material layer, the intermediate resin layer, and the sealant layer by dry laminating using a two-component curable urethane adhesive. In the laminated body, the white printing layer and the chromatic color layer are adjacent to the intermediate resin layer.

(Example 2)
Same as in Example 1 except that the ratio of carbon black and titanium oxide is adjusted so that the brightness of the sealant measured from the side to be bonded to the intermediate layer is L * = 63, and the thickness of the white printing layer is 0.5 μm. The laminate of Example 2 was produced.

(Example 3)
A GL film manufactured by Toppan Printing Co., Ltd. was used as a barrier layer instead of the base material layer. In this film, a coating layer having a thickness of 0.3 μm composed of an aluminum oxide vapor-deposited layer having a thickness of 15 nm and an organic-inorganic hybrid film containing PVA and silicon oxide is laminated in this order on a base film made of stretched PET. It has a structure with a total thickness of 12 μm. A laminate was produced in the same manner as in Example 1 except that the base material layer was changed.

(Comparative Example 1)
Same as Example 1 except that the ratio of carbon black and titanium oxide is adjusted so that the brightness of the sealant measured from the side to be bonded to the intermediate layer is L * = 85, and the thickness of the white printing layer is 1.5 μm. The laminate of Example 2 was produced.

(Measurement method of brightness L *)
The light transmittance was measured with a spectrophotometer (UV-2450, an ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation), and the brightness L * was measured with a spectrophotometer (manufactured by Suga Test Instruments Co., Ltd.).

(Making a packaging bag)
Two laminates of each example having a width of 130 mm and a height of 180 mm were prepared and laminated so that the sealant films face each other. Then, the three sides excluding the upper end were joined by heat sealing with a seal width of 5 mm to prepare packaging bags for each example.

(Preparation of packaging)
The packaging bag of each example was filled with the contents shown below, and the upper ends were joined by heat sealing to prepare the packaging of each example.
Commercially available curry was enclosed as the contents.

(Evaluation of preservation of contents)
The contents enclosed in the packaging of each example were heat-sterilized at 121 ° C. for 30 minutes.
Then, it was stored at room temperature for one week, and a sensory evaluation was carried out to see if the flavor and color of the contents were impaired.

In Example 1, it was confirmed that the packaging bag had a sufficient whiteness L * value and was excellent in design.
In Example 2, the light-shielding property was sufficient, but the thickness of the white print was thinner than that in Example 1, so that the color of the sealant was conspicuous and the whiteness as a packaging bag was slightly inferior.
In Example 3, by further using the barrier film, the result that the flavor of the contents was better than that of the other examples was obtained.
In Comparative Example 1, the whiteness L * value of the packaging bag was superior to that of the other examples, but the contents were deteriorated by light due to insufficient light-shielding property, and it was not suitable as a packaging bag for food preservation. It could be confirmed.

Although one embodiment and the embodiment of the present invention have been described above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like within a range not deviating from the gist of the present invention. Is done.

1A ... Packaging laminate 2 ... Sealant layer 3 ... Intermediate resin layer 4 ... White printing layer 5 ... Barrier layer 6 ... Base material layer

Claims (5)

A packaging laminate in which a base material, a white printing layer formed on the base material, and a sealant layer including a light-shielding layer are laminated at least, and the whiteness of the sealant layer on the white printing layer side is determined. The L * value according to the L * a * b * color system is 45 or more and 65 or less, and the whiteness of the packaging laminate on the opposite surface to the sealant layer is the L * value according to the L * a * b * color system. A packaging laminate having a wavelength of 70 or more and a light transmittance of 30% or less in the wavelength range of 200 to 800 nm. The packaging according to claim 1, wherein the content of titanium oxide in the white ink used for the white printing layer is 0.5% to 30%, and the thickness of the white printing layer is 0.5 μm or more and 2 μm or less. Laminated body for. The packaging laminate according to claim 1 or 2, wherein the white printing layer is laminated on the sealant layer side of the base material. The packaging laminate according to any one of claims 1 to 3, further comprising a barrier layer and a barrier coat layer formed between the base material layer and the sealant layer. The barrier layer is made of a metal oxide, and the barrier coat layer is composed of at least one compound selected from the group consisting of a metal alkoxide, a hydrolyzate of a metal alkoxide, and a polymer of a metal alkoxide, and a hydroxy group-containing polymer. The packaging laminate according to claim 4, which comprises a compound.

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