JP2004122385A - Polyester type shrink label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polyester type shrink label having gentle heat shrinkability excellent in the mounting properties to a container and reconciling low temperature shrinkability and natural shrink preventing properties. <P>SOLUTION: The polyester type shrink label is a shrink label wherein a printing layer is provided on at least one surface of a base film. The base film is constituted of a center layer (A) mainly comprising a polytrimethylene terephthalate type resin (a) and the surface layers (B) mainly comprising a polyethylene terephthalate type resin (b) provided on both sides of the center layer (A). The polyethylene terephthalate type resin (b) preferably contains an alicyclic diol as a diol component along with ethylene glycol and each of the surface layers (B) preferably contains a blocking inhibitor. Further, the thickness of the center layer (A) is 50-90% with respect to that of the base film. <P>COPYRIGHT: (C)2004,JPO

Description

【００６８】
表１より、実施例に係るフィルム原反の熱収縮率（％）は、６０℃という低温であっても、熱収縮性を有しており、また、保管中の自然収縮が少ない。さらにまた、仕上がり状態が良好である。従って、実施例に係るポリエステル系シュリンクラベルは、低温収縮性と、自然収縮防止性とのバランスが良好であり、しかも、容器に装着した際の装着状態も優れている。
【図面の簡単な説明】
【図１】本発明のポリエステル系シュリンクラベルの一例を示す概略断面図である。
【符号の説明】
１　　　シュリンクラベル
２　　　ベースフィルム
２１　　ベースフィルム２の中心層
２２　　ベースフィルム２の表面層
３　　　印刷層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyester shrink label having a gentle heat shrinkage property and having less distortion of a printed design after the heat shrinkage.
[0002]
[Prior art]
Conventionally, heat-shrinkable labels (shrink labels) have been used as labels for glass bottles, plastic containers such as polyethylene terephthalate containers (PET bottles), and as sealing cap seals. As the shrink label, a polyvinyl chloride shrink label printed on a polyvinyl chloride heat-shrinkable film as a base film was used. However, the harmfulness of disposal and incineration, the suitability for recycling PET bottles, etc. Due to the problem described above, polyester shrink labels using a polyester heat-shrinkable film composed of polyethylene terephthalate or a modified product thereof as a base film have been used (see Patent Documents 1 to 3).
[0003]
[Patent Document 1]
JP-A-11-115133
[Patent Document 2]
JP 2001-272915 A
[Patent Document 3]
JP 2002-91316 A
[0004]
[Problems to be solved by the invention]
However, conventional polyester shrink labels do not provide a gradual heat shrinkage compared to conventional polyvinyl chloride shrink labels in their heat shrink suitability, and the printed design after heat shrinkage tends to be distorted. There was a need for improvement.
[0005]
In addition, if the shrink label is excellent in heat shrinkability at low temperatures, it can be applied to containers having poor heat resistance and containers containing contents that are deteriorated by heat. However, if the low-temperature shrinkability is excellent, shrinkage at room temperature (natural shrinkage) is likely to occur, thereby reducing dimensional stability and storage stability. For this reason, conventionally, the degree of low-temperature shrinkage has been considered in consideration of the balance with the natural shrinkage prevention properties, but the low-temperature shrinkage properties and the contradictory properties of the natural shrinkage prevention properties are compatible at an even more excellent level. There is a need for non-polyvinyl chloride shrink labels.
[0006]
Accordingly, an object of the present invention is to provide a polyester-based shrink label that has a moderate heat shrinkage property and is excellent in mountability to a container.
Another object of the present invention is to provide a polyester-based shrink label in which low-temperature shrinkage and natural shrinkage-prevention are compatible at an even higher level.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that heat using polytrimethylene terephthalate resin (also referred to as polypropylene terephthalate resin; sometimes referred to as “PPT resin”) as a polyester resin is used. It has been found that a shrink label made of a shrinkable film shows a gradual shrinkage behavior, but has a large shrinkage ratio when stored at a temperature of about 30 to 40 ° C., and is inferior in practical use. Therefore, as a result of further intensive studies, a shrink label having a PPT-based resin as a central layer and a polyethylene terephthalate-based resin (sometimes referred to as “PET-based resin”) as a surface layer is a characteristic of the PPT-based resin. It has been found that moderate heat shrinkage is maintained and natural shrinkage is suppressed to a small level. The present invention has been completed based on these findings.
[0008]
That is, the present invention relates to a shrink label in which a printing layer is provided on at least one surface of a base film, wherein the base film comprises a polytrimethylene terephthalate-based resin (a) having a central layer (a) as a main component of the resin. A) and a polyester shrink provided on both sides of the center layer (A) and a surface layer (B) containing a polyethylene terephthalate resin (b) as a main component of the resin. Provide a label.
[0009]
The polyethylene terephthalate resin (b) preferably contains an alicyclic diol together with ethylene glycol as a diol component. The surface layer (B) may contain an antiblocking agent. The thickness of the center layer (A) is preferably 50 to 90% with respect to the thickness of the base film.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings as necessary. Note that the same members or parts may be given the same reference numerals.
In the example of FIG. 1, the shrink label 1 includes a base film 2 and a printing layer 3 provided on one surface of the base film 2, and the base film 2 includes a center layer 21 and the center layer 21. And a surface layer (22, 22) provided on both sides of the layer 21. The center layer 21 is formed of a resin composition containing polytrimethylene terephthalate-based resin (a) [PPT-based resin (a)] as a main component of the resin. On the other hand, the surface layers (22, 22) are formed of a resin composition containing polyethylene terephthalate-based resin (b) [PET-based resin (b)] as a main component of the resin.
[0011]
As described above, since the base film 2 has the center layer (A) 21 containing the PPT-based resin (a) as a main component of the resin, the shrink label 1 can exhibit a gradual heat shrinkage property, and Has excellent wearability. In particular, the distortion and vertical shrinkage of the print design after being mounted on the container are suppressed or prevented, and the cutability at the perforations formed in the vertical direction is excellent, so that it is difficult for breakage to occur halfway. .
[0012]
In addition, on both sides of the central layer (A) 21 mainly composed of the PPT resin (a), surface layers (B) (22, 22) mainly composed of the PET resin (b) are provided. Since it is provided, the excellent low-temperature shrinkage due to the PPT-based resin (a) can be effectively exhibited while suppressing or preventing the natural shrinkage of the shrink label 1. Accordingly, the shrink label 1 has good dimensional stability and storage stability, and can be applied to a container having low heat resistance and a container containing contents having low heat resistance.
[0013]
Further, the viscous PPT resin (a) is contained in the center layer (A) 21, and the surface layer (B) (22, 22) contains PET resin (b) as a main component of the resin. Therefore, even if the shrink label 1 (or the base film 2) is wound into a roll and stored, no blocking occurs, and the storability is further improved.
[0014]
[Base film]
The base film 2 has a three-layer structure in which a surface layer (B) 22, a center layer (A) 21, and a surface layer (B) 22 are laminated in this order (that is, the surface layer (B) 22 / the center layer (A)). 21 / surface layer (B) 22).
[0015]
[Center layer (A)]
The central layer (A) 21 contains a PPT resin (a) as a main component of the resin. In the PPT resin (a), the dicarboxylic acid component is mainly composed of terephthalic acid, and the diol component is mainly composed of 1,3-propanediol. The polytrimethylene terephthalate-based resin (a) can be used alone or in combination of two or more.
[0016]
The dicarboxylic acid component in the PPT-based resin (a) is mainly composed of terephthalic acid, and the proportion of terephthalic acid in the entire dicarboxylic acid component is, for example, about 70 to 100 mol% (preferably 80 to 100 mol%). . As dicarboxylic acid components other than terephthalic acid, for example, isophthalic acid, 4,4'-biphenyldicarboxylic acid, 3,3'-stilbendicarboxylic acid, 4,4'-stilbendicarboxylic acid, 4,4'-dibenzyldicarboxylic acid Aromatic dicarboxylic acids such as 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid; malonic acid; Aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecandioic acid; 1,4-decahydronaphthalenedicarboxylic acid, 1,5-decaic acid Hydronaphthalenedicarboxylic acid, 2,6-decahydronaphthalenedicarboxylic acid, 1,4-cy B hexane dicarboxylic acid, and alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid can be used. The dicarboxylic acid components can be used alone or in combination of two or more.
[0017]
The diol component in the PPT-based resin (a) is mainly composed of 1,3-propanediol, and the proportion of 1,3-propanediol in the entire diol component is, for example, 70 to 100 mol% (preferably 80 to 100 mol%). Mol%). Examples of diol components other than 1,3-propanediol include ethylene glycol, propylene glycol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, and 2-diol. Ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1 Aliphatic diols such as 2,6-hexanediol, 2-ethyl-2,4-dimethyl-1,3-hexanediol and 1,8-octanediol; thiodiethanol; polyalkylene glycols such as diethylene glycol; 1,2-cyclohexane Dimethanol, 1,3-cyclohexanedimethanol, 2,2,4,4-tetrame And the like can be used Le 1,3 alicyclic diols such as cyclobutanediol (alicyclic hydrocarbon ring-containing diol). The diol component can be used alone or in combination of two or more.
[0018]
The center layer (A) 21 contains the PPT-based resin (a) as a main component of the resin, and the proportion of the PPT-based resin (a) in the entire resin is, for example, 70 mol% or more (preferably 90 to 90 mol%). 100 mol%). The resin that can be used together with the PPT-based resin (a) is not particularly limited, and includes other polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and a copolymer thereof.
[0019]
[Surface layer (B)]
The surface layers (B) (22, 22) are provided on both sides of the central layer (A) 21 and contain a PET resin (b) as a main component of the resin. In the PET resin (b), the dicarboxylic acid component is mainly composed of terephthalic acid, the diol component is mainly composed of ethylene glycol, and about 10 to 30 mol% of at least one of the dicarboxylic acid component and the diol component. Is preferably modified with other components to lower the crystallinity. The PET resin (b) can be used alone or in combination of two or more.
[0020]
Examples of the dicarboxylic acid component other than terephthalic acid in the PET resin (b) include a dicarboxylic acid component usable as the dicarboxylic acid component in the PPT resin (a). The dicarboxylic acid components can be used alone or in combination of two or more.
[0021]
Examples of the diol component other than ethylene glycol in the PET resin (b) include a diol component usable as the diol component in the PPT resin (a). The diol component can be used alone or in combination of two or more.
[0022]
As the diol component in the PET resin (b), an alicyclic diol is preferably used in combination with ethylene glycol. Specifically, as the PET resin (b), for example, a copolyester in which a dicarboxylic acid component is mainly composed of terephthalic acid and a diol component is composed of ethylene glycol and 1,4-cyclohexanedimethanol is preferably used. it can. In the copolyester, the proportion of terephthalic acid in the whole dicarboxylic acid component is, for example, 95 to 100 mol%, and the total proportion of ethylene glycol and 1,4-cyclohexanedimethanol in the whole diol component is, for example, 80 to 100. Preferably it is mol%. The ratio of ethylene glycol to 1,4-cyclohexane dimethanol is preferably ethylene glycol / 1,4-cyclohexane dimethanol (molar ratio) = 70 to 90/10 to 30. Further, as the diol component in the copolyester, diethylene glycol may be used together with ethylene glycol and 1,4-cyclohexanedimethanol.
[0023]
The surface layer (B) (22, 22) contains the PET resin (b) as a main component of the resin, and the ratio of the PET resin (b) to the entire resin is, for example, 70 mol% or more ( Preferably it is 90-100 mol%). The resin that can be used together with the PET resin (b) is not particularly limited, but includes other polyester resins such as polybutylene terephthalate and polyethylene naphthalate.
[0024]
The surface layer (B) (22, 22) may contain a blocking inhibitor. Examples of the antiblocking agent include inorganic oxides such as silica (amorphous silica and microcrystalline silica), alumina, zinc oxide and magnesium oxide; carbonates such as calcium carbonate and magnesium carbonate; zeolite and calcium silicate; Inorganic particles such as silicates (including aluminosilicate) such as glass beads, talc, clay and mica; and organic particles such as cross-linked polystyrene particles and cross-linked polymethyl methacrylate particles. The shape of the antiblocking agent is, for example, spherical or amorphous, and the average particle size is, for example, about 0.1 to 10 μm. The amount of the antiblocking agent used is, for example, about 0.05 to 1.0% by weight based on the total amount of the constituent components of the surface layer (B) (22, 22).
[0025]
The two surface layers (B) (22, 22) formed on both sides of the center layer (A) 21 may be formed from the same PET resin (b) or different PET resins (b). May be formed.
[0026]
The PPT-based resin (a) and the PET-based resin (b) can be prepared by a known or common polymerization method (eg, a polymerization method by condensation polymerization of a dicarboxylic acid component and a diol component).
[0027]
In the base film 2 having such a three-layer structure, the thickness can be appropriately selected within a range that does not impair the mechanical strength, the handleability of the label, and the like, but is generally 20 to 100 μm (preferably 30 to 100 μm). 60 μm). The ratio of the thickness of the center layer (A) 21 to the base film 2 is desirably about 50 to 90% (preferably 60 to 90%). If the ratio exceeds 90%, the natural shrinkage increases, and if it is less than 50%, the low-temperature shrinkage decreases.
[0028]
The thickness of the center layer (A) 21 can be appropriately selected within a range that does not impair the strength and handleability of the base film, but is, for example, about 10 to 60 μm, and preferably about 20 to 50 μm. When the thickness of the central layer (A) 21 is less than 10 μm, the mountability to a container and low-temperature shrinkage are reduced, and when it exceeds 60 μm, the cost is increased and it is not practical.
[0029]
The thickness of the surface layer (B) (22, 22) is the same or different, and is, for example, about 2 to 15 μm, preferably about 3 to 10 μm. When the thickness of each surface layer (B) (22, 22) is less than 2 μm, the natural shrinkage-preventing property is reduced, and when it exceeds 15 μm, the low-temperature shrinkage property is reduced.
[0030]
The center layer (A) 21 and the surface layer (B) (22, 22) may be provided, if necessary, in addition to the above components, for example, a lubricant, a filler, a heat stabilizer, an antioxidant, an ultraviolet absorber, Various additives such as an inhibitor, a flame retardant, and a colorant may be contained.
[0031]
Each of the center layer (A) 21 and the surface layer (B) (22, 22) may be composed of a plurality of layers. Further, between the central layer (A) 21 and each of the surface layers (B) (22, 22), other heat-shrinking properties, low-temperature shrinking properties, and natural shrinkage preventing properties are not impaired. A resin layer may be provided. Further, the surface of the printing layer of the surface layer (B) (22, 22) may be subjected to a conventional surface treatment such as corona discharge treatment, plasma treatment, and acid treatment in order to improve printability.
[0032]
The base film 2 can be manufactured by a conventional method used when manufacturing a laminated film, for example, a coextrusion method. For example, a resin composition containing a PPT resin (a) forming the center layer (A) 21 and a resin composition containing a PET resin (b) forming the surface layer (B) (22, 22) are used. And a melt-extrusion molding method using a feed block two-type and three-layer type extruder equipped with a T die, cooling by a cooling roll, and stretching. Since both the center layer (A) 21 and the surface layer (B) (22, 22) are formed of a polyester polymer, the base film 2 can be laminated without using an adhesive, but it is necessary. An adhesive layer may be interposed depending on the conditions. Note that an annular die can be used instead of the T die. Further, a resin composition containing a resin for forming each layer is melt-extruded and molded to form a single-layer film of each layer, which is laminated by a known or common laminating method, and then subjected to a stretching treatment to obtain a base film 2. You can also get
[0033]
Stretching can be performed by any of a tenter method and a tube method. The stretching treatment is performed by, for example, stretching at a temperature of about 70 to 100 ° C. in the width direction (transverse direction; TD direction) by 2.0 to 7.0 times, preferably 4.0 to 6.0 times. Is Note that, if necessary, for example, a stretching process can be performed at a low stretching ratio (for example, about 1.5 times or less) also in the length direction (longitudinal direction; MD direction). As described above, the base film 2 in the present invention includes a uniaxially oriented film stretched in only one direction and a biaxially oriented film stretched mainly in one direction and slightly stretched in a direction perpendicular to the direction. included. The base film 2 thus obtained has an orientation in the transverse direction (mainly the direction in which the stretching treatment is performed), and exhibits a large heat shrinkage in the direction.
[0034]
In FIG. 1, the printing layer 3 is formed on one surface of the base film 2. However, in the present invention, the printing layer may be formed on at least one surface of the base film 2. When the printing layer is formed only on one surface of the base film, the surface of the shrink label on the printing layer side is the surface on the adherend (object to be mounted such as a container) (for example, when it is rolled into a cylindrical shape). Inner surface), or a surface on the opposite side to the adherend (for example, an outer surface when it is rolled into a cylindrical shape). Further, an overcoat layer may be provided on the surface of the base film opposite to the adherend by coating.
[0035]
The printing layer 3 is a layer on which product names, illustrations, handling precautions, and the like are displayed, and can be formed by printing using a known printing method such as letterpress rotary printing, silk screen printing, or gravure printing. The printing ink used for forming the printing layer 3 is not particularly limited, and can be appropriately selected according to the printing method. The surface on which characters, designs, and the like are printed is usually the surface that comes into contact with the adherend (such as a container).
[0036]
The thickness of the printing layer 3 is not particularly limited, and is, for example, about 0.1 to 10 μm (preferably 0.5 to 7 μm).
[0037]
In the shrink label 1 of the present invention, the base film 2 is rounded into a cylindrical shape so that the direction in which the stretching process is mainly performed (main stretching direction) is the circumferential direction, and both ends are adhered using a solvent or an adhesive. Thereafter, if necessary, it can be cut to a desired length and used as a cylindrical shrink label. The shrink label may be in any form of a full shrink label, a semi-full shrink label, or a half shrink label.
[0038]
The polyester-based shrink label of the present invention can exhibit moderate heat shrinkage, so that it can be easily attached to a container. Specifically, without causing wrinkles, and with or without reducing the distortion of the print design, and suppressing or preventing vertical shrinkage, it is mounted in a state in which it is tightly adhered to the container. be able to. The term "vertical closing" refers to a phenomenon in which the upper and lower ends of a label partially shrink in the vertical direction and the upper and lower lines become arcuate or wavy.
[0039]
In addition, the polyester shrink label of the present invention has excellent low-temperature shrinkability. Specifically, the heat shrinkage rate is such that when immersed in hot water at 60 ° C. for 10 seconds, the main stretching direction ( 3% or more (for example, 3 to 20%, preferably 8 to 15%) in the direction corresponding to the circumferential direction of the container. Thus, the polyester shrink label of the present invention has heat shrinkability even at a low temperature of 60 ° C. Note that a shrink label made of only polyethylene terephthalate resin does not usually have heat shrinkage at 60 ° C. Further, the temperature at the time of heat shrinkage when the conventional polyester shrink label is attached to the container is usually 70 to 90 ° C., and the polyester shrink label of the present invention can be used at the temperature at the time of heat shrink. The heat shrinkability superior to that of the polyester shrink label can be exhibited.
[0040]
Further, when immersion treatment is performed in hot water at 80 ° C. for 10 seconds, the heat shrinkage in the main stretching direction is, for example, desirably about 30 to 80%, preferably about 40 to 70%.
[0041]
The heat shrinkage can be determined by the following equation.
Heat shrinkage (%) = [{(original length in main stretching direction)-(length after treatment in main stretching direction)] / (original length in main stretching direction)] × 100 (1)
[0042]
The heat shrinkage may be determined by appropriately selecting the type and composition ratio of the resin components of the center layer (A) and the surface layer (B), stretching conditions (stretching temperature, stretching ratio, etc.), heat setting conditions (temperature, time, etc.), and the like. It can be adjusted by selecting.
[0043]
Furthermore, the polyester shrink label of the present invention has excellent anti-natural shrinkage properties. Specifically, when left at 30 ° C. for 30 days, the main stretching direction (corresponding to the circumferential direction of the container) Direction) is 2% or less (preferably 1.8% or less). In general, it is said that there is no practical problem if the natural shrinkage ratio of the shrink label is 2% or less, and that if it exceeds 3%, practical use is difficult.
[0044]
The shrink label is, for example, supplying the cylindrical shrink label to an automatic label mounting apparatus, after cutting to a required length, a container filled with ordinary contents, the container body side surface is substantially entirely It can be attached to a container by being continuously fitted so as to partially or partially cover, and then heat shrunk by heating to be attached. The heat shrinkage of the shrink label fitted to the container may be performed by any known method, and for example, a steam having a temperature in a tunnel of about 70 to 95 ° C. for the reason of uniformly transmitting the temperature and improving the finish of the label. It is preferable that the resin be thermally contracted by passing through a tunnel, but a good finish can be obtained even by using a hot air heater at 80 to 200 ° C.
[0045]
Various containers such as a glass container (for example, various bottles) and a plastic container (for example, a so-called “pet bottle”) can be used as the container. Of course, the contents to be filled in the container are not particularly limited.
[0046]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the polyester shrink label of this invention, it has moderate heat shrinkability and is excellent in the mountability to a container. In addition, the low-temperature shrinkage and the natural shrinkage-prevention are both achieved at an even higher level.
[0047]
【Example】
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
(Preparation example 1 of polyethylene terephthalate resin)
As the polyethylene terephthalate resin, terephthalic acid: 77 mol%, isophthalic acid: 18 mol%, and adipic acid: 5 mol% are used as the dicarboxylic acid component based on the total amount of the dicarboxylic acid component. On the other hand, polymerization was carried out using 92 mol% of ethylene glycol, 5 mol% of butylene glycol (1,4-butanediol), and 3 mol% of diethylene glycol to obtain a polyethylene terephthalate resin having an intrinsic viscosity of 0.76 ( (Sometimes referred to as "polyester A").
[0048]
(Preparation example 2 of polyethylene terephthalate resin)
As the polyethylene terephthalate resin, only terephthalic acid is used as the dicarboxylic acid component, and as the diol component, ethylene glycol: 68 mol%, 1,4-cyclohexane dimethanol: 26 mol%, and diethylene glycol: 6 mol% based on the total amount of the diol component. Was used to prepare a polyethylene terephthalate-based resin (sometimes referred to as “polyester B”).
[0049]
(Preparation example 1 of polytrimethylene terephthalate resin)
As a polytrimethylene terephthalate-based resin, polymerization was performed using only terephthalic acid as a dicarboxylic acid component, only 1,3-propanediol as a diol component, and further using tetrabutyl titanate as a catalyst to obtain an intrinsic viscosity of 0.84. A polytrimethylene terephthalate-based resin (sometimes referred to as "polyester C") was prepared.
[0050]
(Example 1)
Spherical silica fine particles (average particle diameter: 2 μm) were added to polyester A at 900 ppm per weight of polyester A to prepare a polyethylene terephthalate-based resin composition (sometimes referred to as “silica-containing polyester A”).
The silica-containing polyester A and the polyester C are supplied to a co-extruded sheet manufacturing apparatus including two twin-screw vent extruders to form a three-layer structure [silica-containing polyester A / polyester C / silica-containing polyester A]. (Hereinafter sometimes referred to as “polyester ACA sheet”). The polyester ACA sheet has the same layer configuration as the base film 2 in FIG.
[0051]
In addition, the twin-screw extruder of the co-extruded sheet manufacturing apparatus has a strong vent mechanism, and therefore, even if the polyester raw material is supplied without drying, it is possible to remove moisture in the polyester raw material during the extrusion process. Can be. Therefore, in the production method using the twin-screw extruder, it is considered that the hydrolysis of the polymer accompanying the melt extrusion is extremely small.
[0052]
The polyester ACA sheet is stretched 1.1 times in the longitudinal direction at 60 to 80 ° C. and cooled, then sent to a tenter type width stretching machine, and stretched 3.8 times in the width direction at 70 to 90 ° C. At the same temperature as the stretching, a tension heat treatment is carried out for 3 seconds, then a heat treatment is carried out by giving a relaxation of 3% of the entire width in the width direction, and uniform cooling is carried out in the tension state, and further, an end portion (a so-called “ear portion”). )), A film having a thickness of about 50 μm (each of the surface layer having a thickness of 5 μm and the center layer having a thickness of 40 μm) was prepared and wound. The take-up roll is held in an atmosphere of 30 ° C. for 24 hours to perform a strain removal treatment, and then slit to form a 1000 mm-wide film raw material (hereinafter, sometimes referred to as “film raw material A”). Produced.
[0053]
The film raw material A was applied to a gravure printing machine to print a design of 10 colors on one side, and a slit and an end face were sequentially bonded to prepare a ring-shaped polyester shrink label. The inside of the ring of the ring-shaped (tubular) polyester shrink label is the printing surface.
[0054]
(Example 2)
Spherical silica fine particles (average particle size: 2 μm) are added to polyester B at a concentration of 900 ppm per weight of polyester B, and a polyethylene terephthalate-based resin composition (hereinafter sometimes referred to as “silica-containing polyester B”) is used in the same manner as in Example 1. Was prepared.
[0055]
A sheet (“Polyester BCB”) having a three-layer structure [silica-containing polyester B / polyester C / silica-containing polyester B] was prepared in the same manner as in Example 1 except that silica-containing polyester B was used instead of silica-containing polyester A. Sheet).
[0056]
In the same manner as in Example 1 except that a polyester BCB sheet was used in place of the polyester ACA sheet, a film raw material having a thickness of about 50 μm (the thickness of the surface layer was 5 μm and the thickness of the center layer was 40 μm) (“ A film-shaped raw material B) was produced, and a ring-shaped polyester shrink label was prepared in the same manner as in Example 1 except that the raw film B was used.
[0057]
(Comparative Example 1)
Spherical silica fine particles (average particle size: 2 μm) were added to polyester A at 900 ppm per 1 weight of polyester A, and a polyethylene terephthalate-based resin composition (hereinafter sometimes referred to as “silica-containing polyester A”) was used in the same manner as in Example 1. Was prepared. The silica-containing polyester A was supplied to a twin-screw vent extruder to prepare a single-layer sheet of the silica-containing polyester A (sometimes referred to as “polyester A sheet”). The twin screw vent extruder has a strong vent mechanism like the extruder of the first embodiment.
[0058]
In the same manner as in Example 1 except that a polyester A sheet was used in place of the polyester ACA sheet, a film raw material having a thickness of about 50 μm (sometimes referred to as “film raw material C”) was produced. A ring-shaped polyester shrink label was produced in the same manner as in Example 1 except that the film raw material C was used.
[0059]
(Comparative Example 2)
Polytrimethylene terephthalate resin composition (sometimes referred to as "silica-containing polyester C") was prepared by adding 1200 ppm of spherical silica fine particles (average particle size: 2 μm) to polyester C per 1 weight of polyester C. . The silica-containing polyester C was supplied to a twin-screw vent extruder to prepare a single-layer sheet of the silica-containing polyester C (sometimes referred to as “polyester C sheet”). The twin screw vent extruder has a strong vent mechanism like the extruder of the first embodiment.
[0060]
In the same manner as in Example 1 except that a polyester C sheet was used in place of the polyester ACA sheet, a film raw material having a thickness of about 50 μm (sometimes referred to as “film raw material D”) was prepared. A ring-shaped polyester shrink label was produced in the same manner as in Example 1 except that the raw film D was used.
[0061]
(Comparative Example 3)
A mixture of polyethylene terephthalate-based resin and polytrimethylene terephthalate-based resin (sometimes referred to as “polyester ACmix”) was prepared by mixing 20 parts by weight of polyester A and 80 parts by weight of polyester C. Spherical silica fine particles (average particle size: 2 μm) were added to the polyester ACmix at 900 ppm per weight of the polyester ACmix to prepare a composition based on the polyester ACmix (sometimes referred to as “silica-containing polyester ACmix”). The silica-containing polyester ACmix was supplied to a twin-screw vent extruder to produce a single-layer sheet of the silica-containing polyester ACmix (sometimes referred to as a “polyester ACmix sheet”). The twin screw vent extruder has a strong vent mechanism like the extruder of the first embodiment.
[0062]
In the same manner as in Example 1 except that a polyester ACmix sheet was used in place of the polyester ACA sheet, a raw film having a thickness of about 50 μm (sometimes referred to as “film raw material E”) was produced. A ring-shaped polyester shrink label was produced in the same manner as in Example 1 except that the raw film E was used.
[0063]
(Evaluation of heat shrinkage)
The film raw materials (film raw materials A to E) obtained in the examples and comparative examples were immersed in hot water at 60 ° C., 70 ° C., and 80 ° C. for 10 seconds, and then in the width direction of the film raw material ( The length in the TD direction was measured, and the heat shrinkage (%) was determined by the following equation. In addition, the measurement result was shown in the column of "thermal shrinkage rate (%) of raw film" in Table 1.
Heat shrinkage A (%) = [{(original length in direction X)-(length after immersion in direction X)] / (original length in direction X)] × 100
[0064]
(Evaluation of shrink label wearing condition)
The polyester shrink labels obtained in Examples and Comparative Examples were attached to the outer peripheral surface of a 2 L square PET bottle (a container made of polyethylene terephthalate) and passed through a hot air shrink oven for about 3 seconds to shrink (heat shrink). ), And the attached state (finished state) of the polyester shrink label at that time was evaluated according to the following evaluation criteria. The evaluation results are shown in the “finished state” column in Table 1.
Evaluation criteria
Excellent: There are almost no wrinkles, distortions, vertical shrinkage, etc., and the wearing state is extremely good.
Good: There are some wrinkles, distortions, vertical shrinkage, etc., but the wearing state is at a level without any problem.
Acceptable: There are considerable wrinkles, distortion, vertical shrinkage, etc., and it is possible to endure practical use by selectively removing particularly bad ones.
Impossible: Wrinkles, distortion, vertical shrinkage, etc. are extremely large, and are at a level that does not endure practical use.
[0065]
(Evaluation of natural shrinkage)
Further, the polyester shrink labels (polyester shrink labels before shrinkage) obtained in Examples and Comparative Examples were allowed to stand in an atmosphere of 30 ° C. for 30 days in a free state, and the shrinkage ratio after standing (polyester shrinkage). The shrinkage rate in the main shrinkage direction of the label was measured. The measurement results are shown in the column of “natural shrinkage (%)” in Table 1.
[0066]
This shrinkage ratio indicates how much the polyester shrink label shrinks during storage at room temperature or the like, and is also referred to as a natural shrinkage ratio. It is naturally said that the value of the shrinkage ratio is preferably low. Usually, it is said that if it is 2% or less, there is no practical problem, and if it exceeds 3%, it is practically difficult to use.
[0067]
[Table 1]

[0068]
According to Table 1, the heat shrinkage (%) of the film raw material according to the examples has heat shrinkage even at a low temperature of 60 ° C., and the natural shrinkage during storage is small. Furthermore, the finished state is good. Therefore, the polyester shrink label according to the example has a good balance between the low-temperature shrinkage property and the natural shrinkage-preventing property, and also has an excellent mounted state when mounted on a container.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a polyester shrink label of the present invention.
[Explanation of symbols]
1 Shrink label
2 Base film
21 Central layer of base film 2
22 Surface layer of base film 2
3 printing layer

Claims (4)

A shrink label having a printing layer provided on at least one surface of a base film, wherein the base film comprises: a center layer (A) containing a polytrimethylene terephthalate-based resin (a) as a main component; A polyester shrink label comprising: a surface layer (B) having a polyethylene terephthalate resin (b) as a main component of the resin, provided on both sides of the layer (A). The polyester-based shrink label according to claim 1, wherein the polyethylene terephthalate-based resin (b) contains an alicyclic diol together with ethylene glycol as a diol component. 3. The polyester shrink label according to claim 1, wherein the surface layer (B) contains an antiblocking agent. The polyester shrink label according to any one of claims 1 to 3, wherein the thickness of the center layer (A) is 50 to 90% of the thickness of the base film.

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