KR101705243B1 - White heat-shrinkable laminated film and label comprising same - Google Patents

Abstract

The present invention relates to a white heat-shrink lamination film having high light-shielding ability (low light transmittance). The present invention further relates to a packing material including the same and a label. The white heat-shrink lamination film has outstanding ability of shielding visible light and ultraviolet light due to low light transmittance, while exhibiting excellent heat-shrink, thereby effectively preventing spoilage of contents of various dairy products and lactobacillus products. Thus, the white heat-shrink lamination film can be useful as heat-shrink labels and packaging materials for the products.

Description

WHITE HEAT-SHRINKABLE LAMINATED FILM AND LABEL COMPRISING SAME [0002]

The present invention relates to a white heat-shrinkable laminated film having high light-shielding properties (low light transmittance), and heat-shrinkable packaging materials and labels containing the same.

The heat-shrinkable film is generally used for labeling and covering of plastic containers, glass bottles, dry batteries or electrolytic capacitors, as well as for stationary or multiple containers for integrated packing or close packing.

As a heat-shrinkable film, polyvinyl chloride (PVC) film has been used for a long time. The PVC heat-shrinkable film has excellent molding processability and low shrinkage stress, and exhibits excellent properties for labeling and shrink-wrapping in various types and types of containers. However, recently, there has been a problem of causing environmental pollution problems. Accordingly, development of a polyester heat-shrinkable film which is eco-friendly and has an excellent heat shrinkage has been demanded.

The polyester heat-shrinkable film is widely used for packaging and labeling purposes in beverage containers such as PET bottles and other types of containers by utilizing the property of shrinking by heating. Conventionally, in order to label a cylindrical container such as a beverage container or the like, a method is used in which the polyester film is cut into a predetermined size and then rolled, adhered to both ends with a solvent, and then covered with a container to shrink. Therefore, for effective labeling, properties such as high heat shrinkage are required, and the appearance of the film after labeling should be good. For example, Korean Patent Laid-Open Publication No. 2014-0141635 discloses a heat-shrinkable multilayer film in which two thermoplastic resins are alternately laminated, and discloses that the film is suppressed from being deformed by heat press molding.

On the other hand, as compared with general products, there is a high possibility that the products such as milk, lactic acid bacteria and the like are deteriorated due to the influence of the external environment. Therefore, there is a demand for a heat-shrinkable film excellent in shielding property . However, the heat shrinkable films known so far do not exhibit satisfactory shielding properties.

Korean Patent Publication No. 2014-0141635

Accordingly, the present invention aims to provide a white heat-shrinkable laminated film having a high heat shrinkage ratio and light shielding property. The present invention also provides a heat-shrinkable label and packaging material comprising the white heat-shrinkable laminated film.

In order to achieve the above object, the present invention provides a laminated film comprising a two-layer structure of a first surface layer / a base layer or a three-layer structure of a first surface layer / a base layer /

Wherein the base layer comprises a polyester resin and light absorbing particles,

Wherein each of the first surface layer and the second surface layer comprises a polyester resin and light reflection and scattering particles,

Wherein the laminated film has a light transmittance of 15% or less.

The present invention also provides a packaging material and a label comprising the white heat-shrinkable laminated film.

The white heat-shrinkable laminated film of the present invention exhibits excellent heat shrinkability and has a low light transmittance and is excellent in ultraviolet ray and visible ray shielding performance. Therefore, it is possible to effectively prevent deterioration of contents of various kinds of milk and lactic acid bacteria products, Labels and packaging materials.

The white heat-shrinkable laminated film of the present invention is a laminated film comprising a two-layer structure of a first surface layer / a base layer or a three-layer structure of a first surface layer / a base layer / a second surface layer,

Wherein the base layer comprises a polyester resin and light absorbing particles, each of the first surface layer and the second surface layer comprises a polyester resin and light reflection and scattering particles, and the laminated film has a light transmittance of not more than 15% .

The light absorbing particles may be at least one selected from the group consisting of carbon black, carbon nanotube (CNT), and graphene. More specifically, the light absorbing particles may be carbon black.

The light absorbing particles may have an average particle diameter of 5 to 300 nm. More specifically, the light absorbing particles may have an average particle diameter of 10 to 100 nm.

The polyester resin used for the substrate layer may be a polyester homopolymer resin, a polyester copolymer resin, or a blending resin thereof.

As the polyester homopolymer resin, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a mixture thereof, an acid component containing an aromatic dicarboxylic acid as a main component and a glycol component containing an alkylene glycol as a main component are mixed in a usual manner Followed by condensation polymerization. Examples of the aromatic dicarboxylic acid include aromatic dicarboxylic acids such as dimethyl terephthalic acid, terephthalic acid, isophthalic acid, dimethyl-2,5-naphthalene dicarboxylic acid, naphthalene dicarboxylic acid, cyclohexanedicarboxylic acid, diphenoxyethanedicarboxylic acid, Anthracene dicarboxylic acid, and?,? - bis (2-chlorophenoxy) -ethane-4,4-dicarboxylic acid. Examples of the alkylene glycol include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and hexylene glycol.

The polyester homopolymer resin may contain, in addition to the aromatic dicarboxylic acid and the alkylene glycol described above, a second alcohol component imparting an amorphous property to the film. The second alcohol component may impart heat shrinkage and seaming properties to the film. The second alcohol component may be a diol component or an alcohol component having a valence of three or more, but any component capable of lowering the crystallinity of the film by lowering the crystallization of the stretch in the stretching process of the heat- Diol, 1,3-octanediol, 1,3-butanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) Diethylene-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,1- , 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol or a mixture thereof may be used. The second alcohol component may be contained in an amount of 0 to 30 mol%, 0.5 to 30 mol%, or 3 to 30 mol% based on the total amount of all alcohol components including the glycol component.

The polyester homopolymer resin can be produced by polymerizing by a conventional method. For example, a polyester is obtained by a direct esterification method in which a dicarboxylic acid and a diol are directly reacted, an ester exchange method in which a dicarboxylic acid dimethyl ester is reacted with a diol, and the like. The polymerization may be carried out by any of batchwise and continuous methods.

On the other hand, in order to obtain a heat-shrinkable polyester resin having a high heat shrinkage ratio and excellent shrink finishing property, neopentyl glycol or cyclohexanedimethanol is contained in an amount of 10 mol% or more, 12 mol Or more, or 14% or more. The upper limit of the above-mentioned components is not particularly limited, but if it is excessively high, the heat shrinkage ratio may excessively increase or the rupture resistance of the film may deteriorate. Therefore, it may be 40 mol% or less, 35 mol% or less, or 30 mol% or less.

Wherein the substrate layer contains a polyester resin and light absorbing particles in an amount of 99.9 wt% or less and 0.1 wt% or more, and the heat-shrinkable laminated film contains light absorbing particles in an amount of 0.1 wt% or more based on the total weight of the film . In detail, the base layer contains a polyester resin and light absorbing particles in an amount of 90 to 99.9% by weight and 0.1 to 10% by weight, and the heat-shrinkable laminated film has a light absorbing particle of 0.1 to 5 % ≪ / RTI > by weight. When the polyester resin and the light absorbing particle are contained within the above range, the light absorbing particle can have a superior light shielding effect and a high film forming property to the light absorbing particle usage amount.

The base layer may further comprise light reflection and scattering particles.

The light reflection and scattering particles may be at least one selected from the group consisting of titanium dioxide (TiO ₂ ), barium (Ba), silicon dioxide (SiO ₂ ), calcium carbonate (CaCO ₃ ) and clay (kaolin). In detail, the light absorbing particles may be titanium dioxide (TiO ₂ ). The titanium dioxide may be a crystalline form of anatase or rutile, and any form may be used.

The light reflection and scattering particles may have an average particle size of 100 to 1,000 nm. In detail, the light reflection and scattering particles may have an average particle diameter of 200 to 800 nm.

The base layer may contain 5 to 30% by weight of light reflection and scattering particles based on the total weight of the base layer. In detail, the base layer may comprise 8 to 25% by weight of light reflection and scattering particles based on the total weight of the base layer.

Wherein each of the first surface layer and the second surface layer comprises a polyester resin and light reflection and scattering particles in an amount of 90 wt% or less and 10 wt% or more, and the heat shrinkable laminated film has light reflection and / Scattering particles in an amount of 1% by weight or more. In detail, each of the first surface layer and the second surface layer may contain a polyester resin, and light reflection and scattering particles in an amount of 60 to 90% by weight and 10 to 40% by weight. When the polyester resin and the light reflecting and absorbing particles are contained within the above range, the light reflection and scattering effect can be maximized in the state in which the film processability is ensured.

The polyester resin used for the surface layer, and the light reflection and scattering particles, respectively, are as described for the base layer.

Each of the first surface layer, the base layer and the second surface layer may further include additives such as a stabilizer, a colorant, an antioxidant, a defoaming agent, an antistatic agent, and an ultraviolet absorber if necessary. In order to improve the whiteness of the heat-shrinkable film, a fluorescent whitening agent may be further included.

The heat-shrinkable laminated film has a two-layer structure, and the first surface layer and the base layer may have a thickness ratio of 0.5 to 30: 1. In detail, the heat-shrinkable laminated film has a two-layer structure, and the first surface layer and the base layer may have a thickness ratio of 0.5 to 20: 1. More specifically, the heat-shrinkable laminated film may have a two-layer structure, and the first surface layer and the base layer may have a thickness ratio of 0.8 to 15: 1.

The heat-shrinkable laminated film has a three-layer structure, and the first surface layer, the base layer and the second surface layer may have a thickness ratio of 0.5 to 30: 1: 0.5 to 30. In detail, the heat-shrinkable laminated film has a three-layer structure, and the first surface layer, the base layer and the second surface layer may have a thickness ratio of 0.5 to 20: 1: 0.5 to 20. More specifically, the heat-shrinkable laminated film has a three-layer structure, and the first surface layer, the base layer and the second surface layer may have a thickness ratio of 0.8 to 15: 1: 0.8 to 15.

The heat-shrinkable laminated film may include an additional layer in addition to the two- or three-layer structure. The additional layer may comprise a polyester resin, and light absorbing particles or light reflecting and scattering particles. The additional layer may be located between layers of the two- or three-layer structure, or may be located outside the layer. The polyester resin, light reflection and scattering particles, and light absorption particles are as defined above.

The heat-shrinkable laminated film may have a light transmittance of 15% or less. In detail, the heat-shrinkable laminated film may have a light transmittance of 10% or less. More specifically, the heat-shrinkable laminated film may have a light transmittance of 7% or less or 6% or less.

The heat-shrinkable laminated film may show a heat shrinkage rate of 40 to 80% in the longitudinal direction or the width direction when heat-treated at a temperature of 90 DEG C for 10 seconds. In detail, the heat-shrinkable laminated film may exhibit a heat shrinkage ratio of 50 to 75% in the longitudinal direction or the width direction when heat-treated at a temperature of 90 캜 for 10 seconds.

The heat-shrinkable laminated film may have a thickness of 20 to 100 mu m, 30 to 80 mu m, or 35 to 60 mu m.

Hereinafter, the white heat-shrinkable laminated film of the present invention can be produced by the following process.

(1) providing a polyester resin composition comprising a first surface layer and a base layer, respectively, or each of a first surface layer, a base layer and a second surface layer; (2) co-extruding the polyester resin compositions to prepare an unoriented sheet; And (3) stretching the unstretched sheet.

First, the polyester resin can be produced by an esterification reaction between a diol repeating unit and a dicarboxylic acid repeating unit and a solid phase polymerization process according to a conventional method.

Next, the polyester resin compositions are co-extruded (melt-extruded) into different layers according to a conventional method and then cooled to obtain a two-layered unstretched sheet laminated in this order of the first surface layer / 1 surface layer / substrate layer / second surface layer are laminated in this order to prepare an unoriented sheet having a three-layer structure.

Specifically, the melt extrusion can be performed at a temperature of Tm + 30 to Tm + 80 占 폚. The above Tm is the melting point of the polyester resin. Further, it is preferable that the cooling is performed at a temperature of 30 DEG C or less, for example, 15 to 30 DEG C.

Thereafter, the unstretched sheet is stretched in one or both directions of a first direction, for example, a longitudinal direction (machine direction) and a second direction perpendicular to the first direction, for example, a width direction (tenter direction) A desired white heat-shrinkable laminated film can be produced.

Specifically, the unstretched sheet may be uniaxially or biaxially stretched.

The unstretched sheet may be stretched 1.0 to 4.5 times in the first direction, for example, in the longitudinal direction, and 1.0 to 5.0 times in the second direction, for example, in the width direction. More specifically, the unstretched sheet may be stretched 1.0 to 3.5 times in the first direction, for example, in the longitudinal direction, and 3.0 to 4.5 times in the second direction, for example, in the width direction.

The stretching temperature may be Tg + 5 to Tg + 80 占 폚, and in order to further improve the brittleness of the film, the stretching temperature range may be Tg + 10 to Tg + 50 占 폚. The Tg is the glass transition temperature of the polyester resin.

After initiating the heat setting, the film relaxes in the longitudinal and / or width direction and the stretched sheet can be heat set at a temperature of 60 to 240 캜, more specifically 65 to 120 캜.

The white heat-shrinkable laminated film of the present invention thus produced exhibits excellent heat shrinkability and has a low light transmittance and is excellent in ultraviolet ray and visible ray shielding performance. Therefore, it is possible to effectively prevent deterioration of contents of various kinds of milk and lactic acid bacteria, And can be usefully used as heat-shrinkable labels and packaging materials for products. Accordingly, the present invention provides a packaging material or label comprising the white heat-shrinkable laminated film.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[ Example ]

Manufacturing example  One: The substrate layer  Preparation of resin composition

100 mol% of terephthalic acid as a dicarboxylic acid compound, 83 mol% of ethylene glycol as a diol compound and 17 mol% of neopentyl glycol were polymerized to prepare a copolymer polyester resin composition.

Specifically, the dicarboxylic acid compound and the diol compound were placed in an autoclave equipped with a stirrer and a distillation column, and 0.07 parts by weight of manganese acetate as an ester exchange reaction catalyst was added to 100 parts by weight of terephthalic acid. The temperature was raised to 220 ° C, Methanol was removed to allow the reaction to proceed.

When the transesterification reaction was completed, silica having an average particle diameter of 0.28 占 퐉 was added in an amount of 0.07 parts by weight based on 100 parts by weight of terephthalic acid, and 0.4 part by weight of trimethyl phosphate as a stabilizer was added. After 5 minutes, 0.035 part by weight of antimony trioxide and 0.005 part by weight of tetrabutyl titanate were added as a polymerization catalyst, and the mixture was stirred for 10 minutes. Subsequently, the reaction product was transferred to a second reactor equipped with a vacuum apparatus, and then gradually reduced in pressure while being heated to 285 DEG C and polymerized for 210 minutes to obtain a copolymer polyester resin (weight average molecular weight: 54,070, IV viscosity: 0.672) Respectively.

2.5% by weight of carbon black having an average particle diameter of 20 nm (manufacturer: DIC, product name: KL7886) was added to 97.5% by weight of a copolymer polyester resin and mixed to prepare a base layer resin composition. Thereafter, the mixture was filtered with a nylon filter having a 95% cut size of 5 탆 and extruded from the nozzle into a strand shape. The mixture was cooled and solidified using cooling water previously subjected to a filtration treatment (pore size: 1 탆 or less) Followed by cutting to produce a substrate layer resin chip.

Manufacturing example  2: Preparation of surface layer resin composition

12.5% by weight of anatase type titanium dioxide (manufactured by Sakai, product name: SA1) having an average particle diameter of 300 nm was added to 87.5% by weight of the copolymerized polyester resin prepared in the same manner as in Production Example 1 to prepare a surface layer resin composition. Thereafter, the mixture was extruded in a strand shape, cooled and solidified by using cooling water previously subjected to a filtration treatment (pore size: 1 μm or less), and cut into pellets to prepare a surface layer resin chip.

Example  1: White Heat-shrinkable  Production of laminated film

The base layer resin chips prepared in Preparation Example 1 and the surface layer resin chips prepared in Production Example 2 were melt co-extruded through an extruder at 275 ° C and then cooled in a casting roll at 20 ° C to prepare an unoriented sheet. The unstretched sheet was stretched 4.0 times in the width direction at 75 캜, heat treated (heat set) at 70 캜 for 10 seconds and cooled to obtain a two-layer white heat-shrinkable laminated film (first surface layer: = 1: 1).

Example  2 to 16

Except that the content of each component of the base layer resin composition, the content of each component of the surface layer resin composition, the thickness ratio of the base layer and the surface layer, the number of layers and the thickness of the laminated film shown in Table 1 below were changed, A two-layer or three-layer white heat-shrinkable laminated film was produced in the same manner.

Comparative Example  1 to 5

The surface layer resin chips containing the corresponding amounts of titanium dioxide shown in the following Table 1 were melted and extruded through an extruder at 275 DEG C and then cooled in a casting roll at 20 DEG C to prepare an unoriented sheet. The unstretched sheet was stretched 4.0 times in the width direction at 75 캜, heat treated (heat set) at 70 캜 for 10 seconds and cooled to prepare a white heat-shrinkable single-layer film having a thickness of 40 탆.

Experimental Example

The properties of the heat-shrinkable films prepared in Examples 1 to 16 and Comparative Examples 1 to 5 were measured as described below. The measurement results are shown in Table 1 below.

(1) Heat shrinkage measurement

The film sample was cut into a width of 300 mm and a width of 15 mm in the width direction (TD, tenter direction) in which the shrinkage ratio was to be measured, and after 10 seconds of treatment in hot water at 70 ° C, 80 ° C, 90 ° C and 100 ° C, Respectively. Based on the measured values, the heat shrinkage rate was calculated according to the following equation (1).

[Equation 1]

Heat shrinkage percentage (%) = [(initial length - length after heat treatment) / initial length] x 100

(2) Light transmittance measurement

The light transmittance of the film sample was measured according to ASTM-D1003 using a hazemeter (Gardner BYK).

As can be seen from Table 1, the laminated films of Examples 1 to 16 exhibited a high heat shrinkage ratio and a significantly lower light transmittance than that of the single-layer films of Comparative Examples 1 to 5, showing excellent ultraviolet and visible light shielding effects .

Claims (16)

As a laminated film having a three-layer structure of a first surface layer / a base layer / a second surface layer,
Wherein the base layer contains 90 to 99.9% by weight of a polyester resin and 0.1 to 10% by weight of light absorbing particles,
Wherein the first surface layer and the second surface layer each comprise 60 to 90 wt% polyester resin and 10 to 40 wt% of light reflection and scattering particles,
Wherein the laminated film has a light transmittance of 6% or less,
Wherein the first surface layer, the base layer and the second surface layer have a thickness ratio of 5 to 30: 1: 5 to 30,
Wherein the polyester resin is produced by polymerizing a diol component containing ethylene glycol and neopentyl glycol and a dicarboxylic acid component containing terephthalic acid,
Wherein the laminated film has a heat shrinkage ratio of 50 to 75% in a longitudinal direction or a width direction during heat treatment at 90 占 폚 for 10 seconds.
The method according to claim 1,
Wherein the light absorbing particles are at least one selected from the group consisting of carbon black, carbon nanotubes (CNT), and graphene.
The method according to claim 1,
Wherein the light absorbing particles have an average particle diameter of 5 to 300 nm.
The method according to claim 1,
Wherein the base layer further comprises light reflection and scattering particles.
The method according to claim 1 or 4,
Wherein the light reflection and scattering particles are at least one selected from the group consisting of titanium dioxide (TiO ₂ ), barium (Ba), silicon dioxide (SiO ₂ ), calcium carbonate (CaCO ₃ ) and clay (kaolin) Laminated film.
The method according to claim 1 or 4,
Wherein the light reflection and scattering particles have an average particle size of 100 to 1,000 nm.
The method according to claim 1,
Wherein the heat-shrinkable laminated film contains the light absorbing particles in an amount of 0.1 wt% or more based on the total weight of the film.
The method according to claim 1,
Wherein the heat-shrinkable laminated film contains light reflecting and scattering particles in an amount of 1 wt% or more based on the total weight of the film.
delete delete delete delete The method according to claim 1,
Wherein the heat-shrinkable laminated film includes an additional layer in addition to the three-layer structure.
14. The method of claim 13,
Wherein the additional layer comprises a polyester resin and light absorbing particles or light reflecting and scattering particles.
A packaging material comprising the white heat-shrinkable laminated film of claim 1.
A label comprising the white heat-shrinkable laminated film of claim 1.