JP2008273625A - Package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package covered with a label made of a heat-shrinkable coating film and having suitable tearableness. <P>SOLUTION: The heat-shrinkable polyester film for forming the label shrinks mainly in the longitudinal direction. It is regulated so as to have the following properties in respective given ranges: a rate of hot-water heat-shrinkage in the longitudinal direction through 10-second immersion in warm-water at 90°C; a rate of hot-water heat-shrinkage in the width direction through 10-second immersion in warm-water at 90°C; right-angled tearing strength in the width direction after shrinking at 10% in warm-water at 80°C in the longitudinal direction; an Elmendorf ratio at the time of measurement of an Elmendorf tearing load after shrinking at 10% in warm-water at 80°C in the longitudinal direction; and a rate of natural shrinkage after aging at 700 hours or more in an atmosphere of 65% RH at 40°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a package that covers a label formed of a heat-shrinkable film, and more particularly, to a package that is made of a heat-shrinkable film that has a good tearing property.

  In recent years, many packagings that have been heat shrunk on the outside of containers such as glass bottles and plastic bottles are covered with plastic film labels to protect the contents, improve the appearance, and display the contents. It has become to. As such heat-shrinkable plastic films for labels, heat-shrinkable polyester films, heat-shrinkable polystyrene films, heat-shrinkable polyolefin films, heat-shrinkable polyvinyl chloride films, etc. are often used. ing.

  In addition, as an ordinary heat-shrinkable plastic film, a film that greatly shrinks in the width direction is widely used. In such a heat-shrinkable plastic film whose width direction is the main shrinkage direction, the film is stretched at a high magnification in the width direction in order to develop shrinkage characteristics in the width direction, but the longitudinal direction orthogonal to the main shrinkage direction. With regard to the direction, it is often the case that only low-stretching is applied, and some are not stretched. As described above, a film that is only stretched at a low magnification in the longitudinal direction or a film that is stretched only in the width direction has a drawback that the mechanical strength in the longitudinal direction is inferior.

  In addition, since the label of the bottle must be circular and heat-shrinked in the circumferential direction after being attached to the bottle, when the heat-shrinkable film that heat-shrinks in the width direction is attached as a label, the width direction of the film is After the annular body is formed so as to be in the circumferential direction, the annular body must be cut into a predetermined length and attached to the bottle. Therefore, it is difficult to attach a label made of a heat-shrinkable film that shrinks in the width direction to the bottle at a high speed. Therefore, recently, there is a need for a film that thermally shrinks in the longitudinal direction that can be mounted directly around a bottle from a film roll. Furthermore, in recent years, a wrapping method has been developed in which a container is closed by covering the periphery of a synthetic resin single-open container such as a lunch box with a strip-shaped film. It is also suitable for such packaging applications. Therefore, the demand for the film shrinking in the longitudinal direction is expected to increase dramatically in the future.

  In order to eliminate the problems of mechanical strength in the direction perpendicular to the main shrinkage direction as described above, and to develop a function of shrinking in the longitudinal direction, the unstretched film is made longitudinal (also referred to as longitudinal direction), width direction (horizontal direction) In the longitudinal direction, the film is stretched by 2.0 to 5.0 times and then re-stretched by 1.1 times or more in the longitudinal direction to develop shrinkage in the longitudinal direction, and the Young's modulus in the longitudinal direction and the width direction. There is known a heat-shrinkable polyester film in which the Young's modulus is adjusted to be a predetermined value or more (Patent Document 1).

JP-A-8-244114

  However, although the heat-shrinkable polyester film of Patent Document 1 described above has good mechanical strength in the longitudinal direction and the width direction, it cannot be said that the shrinkability in the longitudinal direction, which is the main shrinkage direction, is necessarily sufficient. . That is, when the present inventors performed a supplementary test in a pilot plant (film width = 1.5 m) in order to obtain the heat-shrinkable polyester film of Patent Document 1, the obtained heat-shrinkable polyester film of Patent Document 1 was obtained. Although a certain degree of mechanical strength is exhibited in the longitudinal direction and the width direction, the shrinkage in the longitudinal direction, which is the main shrinking direction, is not necessarily sufficient, and it has been found that the thickness unevenness in the longitudinal direction is large. . In addition, the natural shrinkage rate when left at room temperature for a certain period of time is large, so it is also found that there is a problem that the film roll is tightly wound and the film roll is likely to wrinkle. It was. Furthermore, it has also been found that the heat-shrinkable polyester film obtained by the additional test has poor tearability (openability) when tearing along the direction perpendicular to the main shrinkage direction. In a package coated with a label made of such a heat-shrinkable polyester film having poor openability, resistance is great when the label is torn in a direction orthogonal to the main shrinkage direction, or the label is stretched well. It was found that problems such as inability to tear or tearing at a position different from the perforation occur when there are perforations.

  The object of the present invention is to solve the problems of the heat-shrinkable polyester film of Patent Document 1 described above, and has high shrinkability in the longitudinal direction, which is the main shrinkage direction, and mechanical strength in the width direction perpendicular to the main shrinkage direction. In addition to providing a heat-shrinkable film that has high roll resistance and does not cause tightening in the roll-shaped film that is produced, hardly wrinkles into the film roll, and has good openability, and a label made of such a heat-shrinkable film Is to provide a package with good tearing of the label.

  Among the present inventions, the invention described in claim 1 is a package formed by covering at least a part of the outer periphery with a label based on a heat-shrinkable film as a base material, and is covered. The Elmendorf ratio in the case where the Elmendorf tear load in the direction orthogonal to the main shrinkage direction of the label and the Elmendorf tear load in the main shrinkage direction is measured is 0.5 to 2.0. Examples of the heat-shrinkable film of the present invention include a heat-shrinkable polyester film, a heat-shrinkable polystyrene film, a heat-shrinkable polyolefin film, and a heat-shrinkable polyvinyl chloride film. Further, the perforation means that a plurality of slits are continuously provided in a straight line or a curved line, but also includes one in which only one slit is provided. Furthermore, the shape of the slit constituting the perforation is not particularly limited. On the other hand, the notch refers to a notch provided at the edge of the label, and the shape thereof is not particularly limited. The direction perpendicular to the main shrinkage direction of the coated label or the Elmendorf tear load in the main shrinkage direction is the direction perpendicular to the main shrinkage direction of the film substrate excluding the printed layer of the coated label or the main shrinkage direction. The Elmendorf tear load in the direction of contraction.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the tensile fracture strength in the direction orthogonal to the main shrinkage direction of the coated label is 100 MPa or more and 300 MPa or less. Is. The tensile fracture strength in the direction perpendicular to the main shrinkage direction of the coated label is the tensile fracture strength in the direction perpendicular to the main shrinkage direction of the film substrate excluding the printed layer of the coated label. Say that.

  The invention described in claim 3 is the refractive index in the direction orthogonal to the main shrinkage direction of the film substrate excluding the printed layer of the coated label in the invention described in claim 1 or claim 2. Is 1.570 or more and 1.600 or less.

  The invention described in claim 4 is the invention described in any one of claims 1 to 3, wherein the right angle tear strength in the direction perpendicular to the main shrinkage direction per unit thickness of the coated label is 100 N / mm. The above is 300 N / mm or less. The right-angle tear strength in the direction perpendicular to the main shrinkage direction per unit thickness of the coated label is the perforation main shrinkage direction per unit thickness of the film substrate excluding the printed layer of the coated label. The right-angled tear strength in the direction perpendicular to

  The invention described in claim 5 is the invention described in any one of claims 1 to 4, wherein a perforation or a pair of notches is provided along a direction orthogonal to the main contraction direction of the label. It is a feature.

  The invention described in claim 6 is the invention described in any one of claims 1 to 5, wherein the unstretched film is Tg + 5 ° C. or higher and Tg + 40 ° C. in a state where both ends in the width direction are held by clips in the tenter. After stretching at a magnification of 2.5 times or more and 6.0 times or less in the width direction at the following temperature, after passing through an intermediate zone where no aggressive heating operation is performed, 1 at a temperature of 100 ° C. or more and 170 ° C. or less. Heat treatment over a period of 0.0 seconds to 10.0 seconds, and then cool the film until the surface temperature of the film reaches 30 ° C. or more and 70 ° C. or less, and clip holding portions at both edges in the width direction of the film. After cutting and removing, the film is stretched in the longitudinal direction at a temperature of Tg + 50 ° C. or more and Tg + 80 ° C. or less at a magnification of 2.0 times or more and 5.5 times or less, and then at a cooling rate of 30 ° C./second or more and 70 ° C./second or less. Film table By temperature is cooled until 45 ° C. or higher 75 ° C. or less, and is characterized in that the heat-shrinkable film before forming the label is manufactured.

  The invention described in claim 7 is the invention described in any one of claims 1 to 6, wherein the heat-shrinkable film is a heat-shrinkable polyester film.

  The heat-shrinkable film used as a label for the package of the present invention has high shrinkability in the longitudinal direction, which is the main shrinkage direction, and has high mechanical strength in the width direction perpendicular to the main shrinkage direction, and is manufactured. In the roll-shaped film, no winding tightening occurs, the film roll is difficult to wrinkle, and the unsealing property is good. Therefore, the heat-shrinkable polyester film can be suitably used as a label for a container such as a bottle, and can be attached to a container such as a bottle very efficiently within a short time. When heat-shrinked, a good finish with very little wrinkles due to heat-shrinkage and insufficient shrinkage can be expressed. In addition, the attached label expresses very good openability. Therefore, the package of the present invention has good tearing of the coated label, and when the perforated line is provided in the direction perpendicular to the main contraction direction with a suitable force, the coated label is perforated. I can tear it cleanly along my eyes.

  The package of the present invention is formed by covering at least a part of the outer periphery with a label based on a heat-shrinkable polyester film and subjecting the package to heat shrinkage. Examples include bottles, various bottles, cans, plastic containers such as confectionery and lunch boxes, and paper boxes (hereinafter collectively referred to as packaging objects). In general, when a label based on a heat-shrinkable polyester film is heat-shrinkable and coated on these packaging objects, the label is heat-shrinked by about 2 to 15% to form a package. Adhere closely. The label to be covered with the packaging object may or may not be printed, and has a perforation in a direction perpendicular to the main shrinkage direction of the label. Also good.

  In addition, when a label is coated on a packaging object, a method is adopted in which an annular body is formed in advance so that the main shrinkage direction is the circumferential direction, and then the annular body is covered with the packaging object and thermally contracted. However, when forming an annular body in such a manner, in addition to the method of bonding the heat-shrinkable film using various adhesives, the heat-shrinkable film is melted using a high-temperature heating element. It is also possible to use a method of wearing (melting sealing method) or the like. In addition, when fusing and sealing a heat-shrinkable film, a predetermined automatic bag making machine (for example, Kyoei Printing Machinery Materials Co., Ltd.-RP500) is used, and the fusing blade temperature and angle are set to predetermined conditions (for example, fusing). A method of forming an annular body or a bag at a predetermined speed (for example, 100 pieces / min) after adjusting the blade temperature to 240 ° C. and the blade angle to 70 ° can be employed. In addition, when covering the packaging object with the label, the label is wound around the packaging object, and the overlapped portion is fused and sealed to cover the packaging object and then heat shrink. It is also possible to adopt a method.

  On the other hand, as the heat-shrinkable film for forming a label, a heat-shrinkable polyester film, a heat-shrinkable polystyrene film, a heat-shrinkable polyolefin film, a heat-shrinkable film made of various plastics such as a heat-shrinkable polyvinyl chloride film, etc. Although a shrinkable film can be mentioned, among them, when a heat-shrinkable polyester film is used, the heat resistance of the label is increased, the label has excellent solvent resistance, and the label can be easily incinerated. Since it becomes a thing, it is preferable. Therefore, in the following description, the heat shrinkable polyester film will be mainly described.

  In addition, the package of the present invention can measure the Elmendorf tear load in the direction orthogonal to the main shrinkage direction of the coated label (film substrate excluding the printing layer) and the Elmendorf tear load in the main shrinkage direction by the following methods. The Elmendorf ratio in the case of measurement needs to be 0.5 or more and 2.0 or less.

[Measurement method of Elmendorf ratio]
In accordance with JIS-K-7128, the label was cut into a rectangular shape with a long main shrinkage direction, and then a test piece was prepared by cutting from the edge in the center in the longitudinal direction. Elmendorf tear load (label) in the direction perpendicular to the main shrinkage direction of the label by holding both ends of the test piece and conducting a tensile test at a predetermined tensile speed using Shimadzu Corporation Autograph) Measured as Elmendorf tear load of the film substrate excluding the printed layer). In addition, after cutting the label into a rectangular shape having a long direction perpendicular to the main shrinkage direction, a test piece is prepared by cutting from the edge in the center of the longitudinal direction, and both ends of the test piece are grasped to obtain a predetermined By performing a tensile test at a tensile speed, the Elmendorf tear load (converted as the Elmendorf tear load of the film substrate excluding the printed layer of the label) in the main shrinkage direction of the label is measured. Thereafter, the Elmendorf ratio is calculated using the following equation (6).
Elmendorf ratio = Elmendorf tear load in the direction orthogonal to the main contraction direction ÷ Elmendorf tear load in the main contraction direction

  When the Elmendorf ratio of the label is less than 0.5, it is not preferable that there is a perforation in a direction orthogonal to the main contraction direction, since it is difficult to tear straight along the perforation. On the other hand, if the Elmendorf ratio of the label exceeds 2.0, it is not preferable because it easily breaks at a position shifted from the perforation. The lower limit of the Elmendorf ratio of the label is preferably 0.6 or more, more preferably 0.7 or more, and particularly preferably 0.8 or more. Further, the upper limit of the Elmendorf ratio of the film substrate excluding the printed layer of the label is preferably 1.8 or less, more preferably 1.6 or less, and particularly preferably 1.5 or less.

  Further, the package of the present invention has a tensile fracture strength when the tensile fracture strength in the direction orthogonal to the main shrinkage direction of the coated label (film substrate excluding the printing layer) is measured by the following method. The strength needs to be 100 MPa or more and 300 MPa or less.

[Measurement method of tensile fracture strength]
The label is sampled to a predetermined size according to JIS-K-7127 to obtain a test piece, and both ends (perpendicular to the main shrinkage direction) of the test piece using a universal tensile tester (for example, Autograph manufactured by Shimadzu Corporation) The tensile strength test is performed at a tension speed of 200 mm / min, and the stress value at break (converted as the stress value of the film substrate excluding the printed layer of the label) is calculated.

  When the tensile fracture strength in the direction orthogonal to the main shrinkage direction of the label is less than 100 MPa, the cut property when tearing the label in the direction perpendicular to the main shrinkage direction, if there is a perforation ( On the other hand, if the tensile fracture strength in the direction perpendicular to the main shrinkage direction of the label exceeds 300 MPa, the initial cutability at the time of tearing becomes unfavorable. In addition, the lower limit of the tensile fracture strength is preferably 120 MPa or more, more preferably 140 MPa or more, and particularly preferably 160 MPa or more. Further, the upper limit value of the tensile fracture strength is preferably 280 MPa or less, more preferably 260 MPa or less, and particularly preferably 240 MPa or less.

  The package of the present invention preferably has a refractive index in the direction perpendicular to the main shrinkage direction of the coated label of 1.570 or more and 1.600 or less. If the refractive index in the direction perpendicular to the main shrinkage direction exceeds 1.600, the solvent adhesiveness deteriorates, which is not preferable. On the other hand, if it is less than 1.570, the cut property is deteriorated, which is not preferable. In addition, the upper limit of the refractive index in the direction orthogonal to the main shrinkage direction is preferably 1.595 or less, and more preferably 1.590 or less. Moreover, the lower limit of the refractive index in the direction orthogonal to the main shrinkage direction is preferably 1.573 or more, and more preferably 1.575 or more.

  In addition, the packaging body of the present invention has a right angle tear strength in a direction perpendicular to the main shrinkage direction per unit thickness of the coated label (film substrate excluding the printing layer) when measured by the following method. The right-angle tear strength needs to be 100 N / mm or more and 300 N / mm or less.

[Measurement method of right-angle tear strength]
The label is sampled as a test piece of a predetermined size according to JIS-K-7128. After that, at the time of tensile fracture in the direction perpendicular to the main shrinkage direction of the label under the condition of a tensile speed of 200 mm / min, grasping both ends of the test piece with a universal tensile tester (for example, Autograph manufactured by Shimadzu Corporation) Measure the strength of Then, the right angle tear strength per unit thickness is calculated using the following equation 2.
Right angle tear strength = Strength at tensile fracture ÷ thickness ・ ・ Equation 2

  If the right-angled tear strength in the direction orthogonal to the main shrinkage direction of the label is less than 100 N / mm, it may not be easily broken due to an impact such as dropping during transportation. When the right-angled tear strength in the direction orthogonal to the main shrinkage direction exceeds 300 N / mm, the cut property (easy to tear) at the initial stage of tearing becomes unsatisfactory. The lower limit of the right-angled tear strength is preferably 120 N / mm or more, more preferably 140 N / mm or more, and particularly preferably 160 N / mm or more. Further, the upper limit value of the right-angled tear strength is preferably 280 N / mm or less, more preferably 260 N / mm or less, and particularly preferably 240 N / mm or less.

  Examples of the dicarboxylic acid component constituting the polyester used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and orthophthalic acid, and aliphatics such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. Examples thereof include dicarboxylic acids and alicyclic dicarboxylic acids.

  When an aliphatic dicarboxylic acid (for example, adipic acid, sebacic acid, decanedicarboxylic acid, etc.) is contained, the content is preferably less than 3 mol%. A heat-shrinkable polyester film obtained using a polyester containing 3 mol% or more of these aliphatic dicarboxylic acids has insufficient film stiffness at high-speed mounting.

  Further, it is preferable not to contain a trivalent or higher polyvalent carboxylic acid (for example, trimellitic acid, pyromellitic acid, and their anhydrides). In a heat-shrinkable polyester film obtained using a polyester containing these polyvalent carboxylic acids, it is difficult to achieve a necessary high shrinkage rate.

  Examples of the diol component constituting the polyester used in the present invention include aliphatic diols such as ethylene glycol, 1-3 propanediol, 1-4 butanediol, neopentyl glycol, and hexanediol, and 1,4-cyclohexanedimethanol. Aromatic diols such as alicyclic diol and bisphenol A can be mentioned.

  The polyester used for the heat-shrinkable polyester film used as the label of the package of the present invention is a cyclic diol such as 1,4-cyclohexanedimethanol or a diol having 3 to 6 carbon atoms (for example, 1-3). Polyester having one or more of propanediol, 1-4 butanediol, neopentylglycol, hexanediol, etc.) and having a glass transition point (Tg) adjusted to 60 to 80 ° C. is preferred.

  Further, the polyester used for the heat-shrinkable polyester film may have a total of 10 mol% or more of one or more monomer components that can be an amorphous component in 100 mol% of the polyhydric alcohol component in all the polyester resins. Preferably, it is more preferably 15 mol% or more, and particularly preferably 17 mol% or more. Here, examples of the monomer that can be an amorphous component include neopentyl glycol, 1,4-cyclohexanediol, and isophthalic acid.

  In the polyester used for the heat-shrinkable polyester film, a diol having 8 or more carbon atoms (for example, octanediol) or a trihydric or higher polyhydric alcohol (for example, trimethylolpropane, trimethylolethane, glycerin, diglycerin). Etc.) is preferably not contained. In the heat-shrinkable polyester film obtained by using polyesters containing these diols or polyhydric alcohols, it is difficult to achieve a necessary high shrinkage rate.

  Moreover, it is preferable not to contain diethylene glycol, triethylene glycol, and polyethylene glycol as much as possible in the polyester used for the heat-shrinkable polyester film. In particular, although diethylene glycol is likely to be present because it is a by-product component during polyester polymerization, it is preferable that the content of diethylene glycol is less than 4 mol% in the polyester used in the present invention.

The heat-shrinkable polyester film is heat-shrinked in the longitudinal direction of the film calculated by the following formula 1 from the length before and after shrinkage when treated for 10 seconds in 90 ° C. warm water without load. The rate (that is, the hot water heat shrinkage rate of 90 ° C.) needs to be 40% or more and 80% or less.
Thermal shrinkage rate = {(length before shrinkage−length after shrinkage) / length before shrinkage} × 100 (%)

  If the hot water thermal contraction rate in the longitudinal direction at 90 ° C. is 40% or less, the shrinkage amount is small, so that wrinkles and tarmi are generated on the label after thermal contraction. If the hot-water heat shrinkage rate in the direction is 80% or more, it is not preferable because the shrinkage tends to occur during heat shrinkage or a so-called “jump” occurs when used as a label. In addition, the lower limit value of the hot water heat shrinkage in the longitudinal direction at 90 ° C. is preferably 45% or more, more preferably 50% or more, and particularly preferably 55% or more. Further, the upper limit value of the hot water heat shrinkage in the longitudinal direction at 90 ° C. is preferably 75% or less, more preferably 70% or less, and particularly preferably 65% or less.

    The heat-shrinkable polyester film is heated in the width direction of the film calculated by the above equation 1 from the length before and after shrinkage when treated for 10 seconds in 90 ° C. warm water without load. The shrinkage rate needs to be 0% or more and 15% or less.

  If the hot water thermal contraction rate in the width direction at 90 ° C. is less than 0%, it is not preferable because a good shrink appearance cannot be obtained when used as a label on a bottle, and conversely, the hot water heat heat in the width direction at 90 ° C. When the shrinkage rate exceeds 15%, it is not preferable because when used as a label, the shrinkage tends to occur during heat shrinkage. In addition, the lower limit of the hot water heat shrinkage in the width direction at 90 ° C. is preferably 2% or more, more preferably 3% or more, and particularly preferably 4% or more. Moreover, the upper limit of the hot water temperature thermal contraction rate in the width direction at 90 ° C. is preferably 14% or less, more preferably 13% or less, and particularly preferably 11% or less.

The heat-shrinkable polyester film needs to have a natural shrinkage ratio of 0.05% or more and 1.5% or less after aging in an atmosphere of 40 ° C. and 65% RH for 700 hours or more. . The natural shrinkage rate can be calculated using the following equation 4.
Natural shrinkage rate = {(length before aging−length after aging) / length before aging} × 100 (%)

  When the natural shrinkage rate is 1.5% or less, when a product wound in a roll shape is stored, winding tightening occurs, and the film roll is likely to wrinkle, which is not preferable. The smaller the natural shrinkage rate, the better. However, from the viewpoint of measurement accuracy, about 0.05% is considered to be the lower limit. The natural shrinkage rate is preferably 1.3% or less, more preferably 1.1% or less, and particularly preferably 1.0% or less.

  On the other hand, in the present invention, the maximum heat shrinkage stress value in the longitudinal direction of the film is preferably 4 MPa or more and 25 MPa or less. When the maximum heat shrinkage stress value in the longitudinal direction of the film is less than 4 MPa, the label rotates with the cap when the PET bottle cap is opened when the container is heat-shrinked by being attached to a container such as a PET bottle. This may cause a situation where the opening of the cap is deteriorated. On the other hand, if the maximum heat shrinkage stress value in the longitudinal direction of the film exceeds 25 MPa, the sealed portion may be removed or the appearance may be deteriorated when the film is attached to a container such as a PET bottle and thermally contracted. (That is, the finish is deteriorated), which is not preferable. The lower limit of the maximum heat shrinkage stress value in the longitudinal direction of the film is more preferably 6 MPa or more, and particularly preferably 7 MPa or more. Further, the upper limit of the maximum heat shrinkage stress value in the longitudinal direction of the film is more preferably 23 MPa or less, and particularly preferably 21 MPa or less.

  In addition, in the present invention, the fusing seal strength of the film is preferably 8 N / 15 mm or more. When the fusing seal strength of the film is less than 8 N / 15 mm, the fusing seal part may be removed when the film is heat-shrinked and attached to a container such as a PET bottle as a label, or the container after heat-shrinking is dropped. Since the fusing seal part may come off, it is not preferable. The higher the fusing seal strength of the film, the better, and it can be increased to substantially the same level as the tensile rupture strength of the film. The fusing seal strength of the film is more preferably 10 N / 15 mm or more, further preferably 12 N / 15 mm or more, and particularly preferably 14 N / 15 mm or more.

  Furthermore, the heat-shrinkable polyester film preferably has a solvent adhesive strength of 4 (N / 15 mm) or more. If the solvent adhesive strength is less than 4 (N / 15 mm), it is not preferable because the label is easily peeled off after the heat shrinkage. The solvent adhesive strength is more preferably 4.5 (N / 15 mm) or more, and particularly preferably 5 (N / 15 mm) or more.

  In addition, the heat-shrinkable polyester film preferably has a thickness variation of 10% or less in the longitudinal direction. When the thickness unevenness in the longitudinal direction is more than 10%, it is not preferable because printing spots are likely to occur during printing at the time of label production or shrinkage spots after heat shrinkage are likely to occur. In addition, the thickness variation in the longitudinal direction is more preferably 8% or less, and more preferably 6% or less.

  The heat shrinkage rate, the maximum heat shrinkage stress value, the solvent adhesive strength, and the thickness unevenness of the film in the longitudinal direction of the heat shrink film are achieved by using the preferred film composition described above and combining with the preferred production method described later. Is possible.

  Furthermore, it is preferable that the heat-shrinkable polyester film does not detect the endothermic curve peak during melting point measurement in differential scanning calorimetry (DSC). By making the polyester constituting the film amorphous, the peak of the endothermic curve at the time of measuring the melting point becomes more difficult to express. Highly amorphous to such an extent that the endothermic curve peak at the time of melting point measurement does not appear, thereby improving the solvent adhesion strength and increasing the heat shrinkage rate and the maximum heat shrinkage stress value, and controlling them within the above-mentioned preferable ranges. Easy to do.

  The thickness of the heat-shrinkable polyester film is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 100 μm.

  Further, the heat-shrinkable polyester film is obtained by melt-extruding the above-described polyester raw material with an extruder to form an unstretched film, and biaxially stretching the unstretched film by the following method and heat-treating it. be able to.

  When the raw material resin is melt-extruded, the polyester raw material is preferably dried using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer. After the polyester raw material is dried in such a manner, it is melted at a temperature of 200 to 300 ° C. and extruded into a film using an extruder. For this extrusion, any existing method such as a T-die method or a tubular method can be employed.

  And an unstretched film can be obtained by rapidly cooling the sheet-like molten resin after extrusion. In addition, as a method of rapidly cooling the molten resin, a method of obtaining a substantially unoriented resin sheet by casting the molten resin on a rotating drum from a die and rapidly solidifying it can be suitably employed.

  Further, as will be described later, the obtained unstretched film was stretched in the width direction under predetermined conditions, and then heat-treated once, and then stretched in the longitudinal direction under predetermined conditions. By rapidly cooling, it becomes possible to obtain a heat-shrinkable polyester film used as a label for the package of the present invention. Hereinafter, regarding the preferred biaxial stretching / heat treatment method for obtaining the heat-shrinkable polyester film used in the package of the present invention, the difference from the conventional biaxial stretching / heat treatment method of the heat-shrinkable polyester film is considered. However, this will be described in detail.

[Preferable stretching and heat treatment method for heat-shrinkable polyester film]
A normal heat-shrinkable polyester film is produced by stretching an unstretched film in the direction in which it is desired to shrink. Although there was a high demand for heat-shrinkable polyester films that shrink in the longitudinal direction from the past, simply stretching an unstretched film in the longitudinal direction makes it impossible to produce a wide film, resulting in poor productivity and thickness. A film with good spots cannot be produced. Moreover, if the method of extending | stretching to a longitudinal direction after extending | stretching previously to the width direction is employ | adopted, the shrinkage | contraction amount to a longitudinal direction will become inadequate, or it will shrink | contract unnecessarily in the width direction. As described above, JP-A-8-244114 discloses a method of stretching an unstretched film in the order of length-width-length under predetermined conditions in order to improve the mechanical properties in the longitudinal direction. However, according to the pilot test by the inventors of the present inventors, such a method cannot obtain a film having sufficient shrinkability in the longitudinal direction, which is the main shrinkage direction, and the width of the manufactured film roll. It was found that wrinkles in the direction are likely to occur. In addition, if the longitudinal stretching ratio (the first stage longitudinal stretching ratio or the second stage longitudinal stretching ratio) is increased to increase the contractibility in the longitudinal direction, the film is finally stretched in the longitudinal direction. It has also been found that it is difficult to carry out a continuous and stable production due to frequent breaks. Moreover, the film obtained by the additional test had a large natural shrinkage rate, wrinkles in the longitudinal direction occurred in the produced film roll, and the unsealing property was also poor.

In order to finally increase the amount of contraction in the longitudinal direction, the present inventors have disadvantaged the method of stretching in the longitudinal direction after biaxial stretching in the longitudinal direction and the width direction as disclosed in JP-A-8-244114. It was considered that it would be more advantageous to simply stretch in the width direction and then stretch in the longitudinal direction. And in such a method of stretching in the longitudinal direction after stretching in the width direction (hereinafter, simply referred to as a transverse-longitudinal stretching method), the hot water temperature shrinkage rate in the longitudinal direction of the film, the natural shrinkage rate, depending on the conditions in each stretching step, We have intensively studied how the openability changes. As a result, the present inventors have found out that when the film is manufactured by the transverse-longitudinal stretching method, the following measures are taken to increase the amount of shrinkage in the longitudinal direction, thereby enabling continuous and stable production. In addition, when the following measures are taken, the natural shrinkage rate of the film is reduced, wrinkles are difficult to enter into the film roll after manufacture, and the perforation opening property of the film is remarkably good. It turns out that there is a surprising side effect that And the present inventors came to devise this invention based on those knowledge.
(1) Control of shrinkage stress after stretching in the width direction (2) Interruption of heating between stretching in the width direction and intermediate heat treatment (3) Trimming of film edge before stretching in the longitudinal direction ( 4) Control of cooling rate of film after longitudinal stretching Hereinafter, each of the above-mentioned means will be sequentially described.

(1) Control of shrinkage stress after stretching in the width direction In the production by the horizontal-longitudinal stretching method of the film used as the label of the packaging body of the present invention, after the unstretched film is stretched in the width direction, it is 100 ° C or higher. It is necessary to perform heat treatment (hereinafter referred to as intermediate heat treatment) at a temperature of less than 170 ° C. for a period of 1.0 second to 10.0 seconds. By performing such an intermediate heat treatment, it is possible to obtain a film that has good cutability in the direction orthogonal to the main shrinkage direction and does not cause shrinkage spots when used as a label. The reason why it is possible to obtain a film having good cutability and no shrinkage spots by performing a specific intermediate heat treatment after transverse stretching is not clear, but by performing a specific intermediate heat treatment, the width direction It is thought that it is possible to reduce the shrinkage stress in the width direction while leaving some molecular orientation in the film. In addition, the minimum of the temperature of heat processing is preferable in it being 110 degreeC or more, and it is more preferable in it being 115 degreeC or more. Moreover, the upper limit of the temperature of heat processing is preferable in it being 165 degrees C or less, and it is more preferable in it being 160 degrees C or less. On the other hand, the heat treatment time needs to be appropriately adjusted according to the raw material composition within a range of 1.0 second to 10.0 seconds.

  In addition, the unstretched film is stretched in the width direction at a temperature of Tg + 5 ° C. or more and Tg + 40 ° C. or less at a magnification of 2.5 times or more and 6.0 times or less in a state where both ends of the width direction are held by clips in the tenter It is necessary to do so. If the stretching temperature is lower than Tg + 5 ° C., it is not preferable because breakage is likely to occur during stretching. On the other hand, if it exceeds Tg + 40 ° C., thickness unevenness in the width direction is deteriorated, which is not preferable. The lower limit of the transverse stretching temperature is preferably Tg + 10 ° C. or more, and more preferably Tg + 15 ° C. or more. Moreover, the upper limit of the temperature of transverse stretching is preferably Tg + 35 ° C. or less, and more preferably Tg + 30 ° C. or less. On the other hand, if the draw ratio in the width direction is less than 2.5 times, not only the productivity is deteriorated but also the thickness unevenness in the width direction is deteriorated, and on the contrary, if it exceeds 6.0 times, breakage occurs at the time of drawing. In addition, it is not preferable because a large amount of energy and a large apparatus are required for relaxation, and productivity deteriorates. In addition, the lower limit of the transverse stretching ratio is preferably 3.0 times or more, and more preferably 3.5 times or more. Further, the upper limit of the transverse stretching ratio is preferably 5.5 times or less, and more preferably 5.0 times or less.

(2) Interruption of heating between stretching in the width direction and intermediate heat treatment In the production by the transverse-longitudinal stretching method of the film used as a label of the package of the present invention, as described above, the intermediate heat treatment is performed after the transverse stretching. Although it is necessary to apply, it is necessary to pass through the intermediate zone which does not perform an active heating operation over the time of 0.5 second or more and 3.0 second or less between those transverse stretching and intermediate heat treatment. . That is, in consideration of production cost, it is preferable to perform transverse stretching and intermediate heat treatment in the same tenter. However, in the production of the film used in the present invention, the transverse stretching zone and the heat treatment zone in the tenter It is preferable to provide an intermediate zone between them. In addition, in the intermediate zone, when the strip-shaped paper piece is hung in a state where the film is not passed through, the hot air from the stretching zone and the heat treatment zone is blocked so that the paper piece hangs almost completely in the vertical direction. Is preferred. And in manufacture of the film used by this invention, it is preferable to guide the film after transverse stretching to this intermediate zone, and to let the intermediate zone pass over predetermined time. If the time for passing through the intermediate zone is less than 0.5 seconds, the hot air in the transverse stretching zone flows into the heat fixing zone due to the accompanying flow of the passing film, which makes it difficult to control the temperature of the intermediate heat treatment in the heat fixing zone. . On the contrary, it is sufficient that the time for passing through the intermediate zone is 3.0 seconds, and setting it longer than that is not preferable because it wastes equipment. The lower limit of the time for passing through the intermediate zone is preferably 0.7 seconds or more, and more preferably 0.9 seconds or more. Further, the upper limit of the time for passing through the intermediate zone is preferably 2.5 seconds or less, and more preferably 2.0 seconds or less.

(3) Trimming of film end before being stretched in the longitudinal direction In the production by the horizontal-longitudinal stretching method of the film used as the label of the packaging body of the present invention, before the film subjected to the intermediate heat treatment is stretched in the longitudinal direction. In addition, it is preferable to trim a thick portion (mainly a clip gripping portion at the time of transverse stretching) that is not sufficiently transversely stretched at the edge of the film. More specifically, a thick portion at the edge of the film using a tool such as a cutter in a portion having a thickness of about 1.1 to 1.3 times the thickness of the central portion located at the right and left edges of the film. It is preferable that only the remaining portion is stretched in the longitudinal direction while cutting the thick portion and removing the thick portion. In addition, when trimming the film edge as described above, it is preferable to cool the film so that the surface temperature of the film before trimming is 50 ° C. or less. By cooling the film in this way, trimming can be performed without disturbing the cut surface. In addition, trimming of the film edge can be performed using a normal cutter or the like, but if a round blade having a circumferential cutting edge is used, a situation in which the cutting edge is locally dulled does not occur, and the film edge is This is preferable because it can continue to be cut sharply over a long period of time and does not cause a breakage during stretching in the longitudinal direction.

  In this way, by trimming the end of the film before stretching in the longitudinal direction, the film once heat-set can be stretched uniformly in the longitudinal direction, and for the first time, stable and continuous production without breakage is possible. It becomes. In addition, it is possible to obtain a film having a large shrinkage in the longitudinal direction (main shrinkage direction). Furthermore, since the film can be uniformly stretched in the longitudinal direction, a film having a small thickness unevenness in the longitudinal direction can be obtained. In addition, by trimming the end of the film, bowing during stretching in the longitudinal direction is avoided, and a film having a small difference in physical properties between the left and right can be obtained.

(4) Control of cooling rate of film after longitudinal stretching In the production by the lateral-longitudinal stretching method of the film used as the label of the packaging body of the present invention, as described above, after the intermediate heat treatment is performed after the lateral stretching, the longitudinal direction After stretching the film, the film is preferably cooled at a cooling rate of 30 ° C./second or more and 70 ° C./second or less until the surface temperature becomes 45 ° C. or more and 75 ° C. or less. Thus, the natural shrinkage rate can be reduced for the first time by cooling the film at an appropriate speed. If the cooling rate is lower than 30 ° C./second or the surface temperature after cooling is higher than 75 ° C., a low natural shrinkage rate cannot be obtained. On the other hand, if the cooling rate is so rapid that the cooling rate exceeds 70 ° C./second, the degree of shrinkage in the width direction of the film (so-called neck-in) increases, and the film surface is easily damaged, which is not preferable. .

  Note that only one of the above-mentioned means (1) to (4) is effective for heat shrinkability in the longitudinal direction of the film, perforation openability, low natural shrinkage, and stable film-forming properties. It does not contribute, but by using the means of (1) to (4) in combination, the heat shrinkability in the longitudinal direction, the perforation opening property, the low natural shrinkage rate, and the stable film forming property It is thought that it becomes possible to express.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments of the examples, and can be appropriately changed without departing from the spirit of the present invention. is there. Tables 1 and 2 show the properties, compositions, examples, and film production conditions (stretching / heat treatment conditions, etc.) of the raw materials used in the examples and comparative examples, respectively.

  The evaluation method of the film is as follows.

[Thermal shrinkage (hot water thermal shrinkage)]
The film is cut into a 10 cm × 10 cm square, heat-shrinked by treatment in warm water at a predetermined temperature ± 0.5 ° C. for 10 seconds under no load condition, and then measured in the vertical and horizontal dimensions of the film. According to the above formula 1, the thermal shrinkage rate was obtained. The direction in which the heat shrinkage rate is large was taken as the main shrinkage direction.

[Tg (glass transition point)]
Using a differential scanning calorimeter (model: DSC220) manufactured by Seiko Denshi Kogyo Co., Ltd., 5 mg of an unstretched film was heated from −40 ° C. to 120 ° C. at a heating rate of 10 ° C./min, and the endotherm obtained. Obtained from the curve. A tangent line was drawn before and after the inflection point of the endothermic curve, and the intersection was defined as Tg (glass transition point).

[Tm (melting point)]
Using a differential scanning calorimeter (model: DSC220) manufactured by Seiko Denshi Kogyo Co., Ltd., 5 mg of an unstretched film was sampled, and from the peak temperature of the endothermic curve when the temperature was raised from room temperature at a heating rate of 10 ° C./min. Asked.

[Thickness unevenness in the main shrinkage direction]
The film was sampled into a long roll having a length of 30 m and a width of 40 mm, and measured at a speed of 5 (m / min) using a continuous contact thickness gauge manufactured by Micron Measuring Instruments Co., Ltd. In the sampling of the roll-shaped film sample described above, the length direction of the film sample was set as the main shrinkage direction of the film. The maximum thickness at the time of measurement was Tmax, the minimum thickness was Tmin., The average thickness was Tave.
Thickness unevenness = {(Tmax.−Tmin.) / Tave.} × 100 (%)

[Solvent adhesive strength]
Sealing was performed by applying 1,3-dioxolane to the stretched film and bonding the two together. Thereafter, the seal portion is cut to a width of 15 mm in a direction orthogonal to the main shrinkage direction of the film (hereinafter referred to as the orthogonal direction), and set in a universal tension tester STM-50 manufactured by Baldwin Co., Ltd. A 180 ° peel test was performed at 200 mm / min. And the tensile strength at that time was made into solvent adhesive strength.

[Fusing seal strength]
Using an automatic bag making machine (model: RP500) manufactured by Kyoei Printing Machinery Materials Co., Ltd., a cutting blade with a blade angle of 70 degrees was made at 240 ° C. at a heating bag making speed of 100 bags / min. After that, the fusing seal part of the bag-made product is cut into a strip shape having a width of 15 mm to prepare a sample piece, and using a Tensilon (model: STM-T-50BP) manufactured by Toyo Baldwin, the distance between chucks is 50 mm The peel strength was measured by conducting a tensile test at a tensile speed of 200 mm / min. And the average value of the peeling strength calculated | required about ten sample pieces was made into the fusing seal strength.

[Maximum heat shrinkage stress value]
The stretched film was cut into a size of main shrinkage direction × direction orthogonal to the main shrinkage direction = 200 mm × 15 mm. Thereafter, a universal tensile testing machine STM-50 manufactured by Baldwin Co., Ltd. was adjusted to a temperature of 90 ° C., the cut film was set, and the stress value when held for 10 seconds was measured.

[Haze]
Based on JIS-K-7136, it measured using the haze meter (Nippon Denshoku Industries Co., Ltd. make, 300A). In addition, the measurement was performed twice and the average value was calculated | required.

[Refractive index]
Using an “Abbe refractometer 4T type” manufactured by Atago Co., Ltd., each sample film was measured after being allowed to stand in an atmosphere of 23 ° C. and 65% RH for 2 hours or more.

[Natural shrinkage]
The obtained film was cut into a size of main shrinkage direction × orthogonal direction = 200 mm × 30 mm and allowed to stand (aging) for 4 hours in an atmosphere of 40 ° C. × 65% RH, and then the main shrink direction of the film (Examples 1 to 1). 6 and Comparative Examples 1 to 3 and 5 were measured for the amount of shrinkage in the longitudinal direction, and in Comparative Example 4 was the width direction), and the natural shrinkage rate was calculated by Equation 4 above.

  Moreover, the evaluation method of the label after coating is as follows.

[Measurement method of tensile fracture strength]
The label attached to the PET bottle is peeled off, and the label is sampled into a rectangular shape having a length of 50 mm in the direction orthogonal to the main contraction direction and a length of 20 mm in the main contraction direction in accordance with JIS-K-7127. Using a universal tensile testing machine (manufactured by Shimadzu Corp., Autograph) as a piece, grasp both ends (both ends in the longitudinal direction) of the test piece and perform a tensile test under the condition of a tensile speed of 200 mm / min. The stress value at break was calculated as the tensile fracture strength.

[Right-angle tear strength]
A test piece was prepared by peeling off the label attached to the PET bottle and sampling the label into the shape shown in FIG. 1 in accordance with JIS-K-7128. The direction is the perforation direction of the label). After that, using a universal tensile testing machine (manufactured by Shimadzu Corp., Autograph), grasp both ends of the test piece and pull in the direction perpendicular to the main shrinkage direction of the label at a pulling speed of 200 mm / min. The strength at the time of fracture was measured, and the right angle tear strength per unit thickness was calculated using Equation 2 above.

[Elmendorf ratio]
The label attached to the PET bottle is peeled off, and the label is cut into a size of 37.5 mm × 31.5 mm in the direction of main shrinkage × direction perpendicular to the main shrinkage direction according to JIS-K-7128. A test piece was prepared by making a slit (cut) of 10 mm from the center of the edge along the direction so as to be orthogonal to the edge. Then, using a universal tensile tester (Autograph, manufactured by Shimadzu Corporation), both ends of the produced test piece are grasped, and a tensile test is performed under the condition of a tensile speed of 200 mm / min. The Elmendorf tear load was measured. Moreover, the direction orthogonal to the main shrinkage | contraction direction of a film and the main shrinkage | contraction direction were replaced, the test piece was produced, and the Elmendorf tear load of the direction orthogonal to the main shrinkage | contraction direction was measured. Then, the Elmendorf ratio was calculated from the obtained main contraction direction and the Elmendorf tear load in the direction orthogonal to the main contraction direction using the above equation 6.

[Refractive index]
The label attached to the PET bottle is peeled off, the printing applied to the surface of the label is removed with a solvent (ethyl acetate, methyl ethyl ketone, etc.), and the label is left in an atmosphere of 65% RH for 2 hours or more. The measurement was performed using an “Abbe refractometer 4T type” manufactured by the company. The refractive index was measured by the method described above.

[Opening rate when falling down]
Fill a plastic bottle with a label with 500 ml of water, and leave the plastic bottle in a refrigerator adjusted to about 5 ° C for 8 hours or more, then drop it from a height of 1 m with the perforated part down And the ratio (%) of the perforated tears was calculated (n = 100).

[Shrink finish]
The finished state of the label mounted around the PET bottle was visually evaluated according to the following criteria.
◎: No wrinkles, jumping up, insufficient shrinkage, and no color spots are observed ○: Wrinkles, jumping up, or insufficient shrinkage cannot be confirmed, but some color spots are seen △: Jumping Neither ascending nor insufficient shrinkage has occurred, but spots on the neck are observed. ×: Wrinkles, jumping up, insufficient shrinkage occurred

[Label adhesion]
Sensory evaluation was performed on the degree of label displacement when the attached label and the PET bottle were lightly twisted. If the label did not move, it was marked as ◯.

[Perforation opening]
Fill the plastic bottle with the label with 500 ml of water, refrigerate to 5 ° C, tear the perforation of the bottle label immediately after taking it out of the refrigerator with your fingertips, tear it cleanly along the perforation in the vertical direction, and remove the label The number of bottles that could be removed from the bottle was counted, and the ratio (%) to 50 samples was calculated.

  Moreover, the polyester used for the Example and the comparative example is as follows.

Polyester 1: Polyester composed of 70 mol% ethylene glycol, 30 mol% neopentyl glycol and terephthalic acid (IV 0.72 dl / g)
Polyester 2: Polyethylene terephthalate (IV 0.75 dl / g)
Polyester 3: Consists of 82.5 mol% of terephthalic acid units and 17.5 mol% of isophthalic acid units as the dicarboxylic acid component, and ethylene glycol as the diol component.

[Example 1]
<Preparation of heat-shrinkable film roll>
The above polyester 1 and polyester 2 were mixed at a weight ratio of 90:10 and charged into an extruder. Thereafter, the mixed resin was melted at 280 ° C., extruded from a T-die, wound around a rotating metal roll cooled to a surface temperature of 30 ° C., and rapidly cooled to obtain an unstretched film having a thickness of 360 μm. At this time, the take-up speed of the unstretched film (rotational speed of the metal roll) is about 20 m / min. Met. Moreover, Tg of the unstretched film was 67 degreeC. Thereafter, the unstretched film was guided to a tenter (first tenter) in which a transverse stretching zone, an intermediate zone, and an intermediate heat treatment zone were continuously provided. In the tenter, the length of the intermediate zone located between the transverse stretching zone and the intermediate heat treatment zone is set to about 40 cm. In addition, in the intermediate zone, when the strip-shaped paper piece is hung in a state where the film is not passed through, the hot air from the stretching zone and the hot air from the heat treatment zone are blown so that the paper piece hangs almost completely in the vertical direction. Blocked.

  And after preheating the unstretched film led to the tenter until the film temperature reaches 90 ° C., the film is stretched 4 times at 75 ° C. in the transverse direction in the transverse stretching zone and passed through the intermediate zone (pass Time = about 1.2 seconds), the film was led to an intermediate heat treatment zone and heat treated at a temperature of 130 ° C. for 2.0 seconds to obtain a transversely uniaxially stretched film having a thickness of 90 μm. Thereafter, using a pair of left and right trimming devices (configured by a round blade having a circumferential cutting edge) provided behind the tenter, the edge of the laterally uniaxially stretched film (about the thickness of the film at the center) A portion having a thickness of 1.2 times) was cut, and the end portion of the film located outside the cut site was continuously removed.

    Further, the film having the edge trimmed as described above is guided to a longitudinal stretching machine in which a plurality of roll groups are continuously arranged, and preheated until the film temperature reaches 70 ° C. on the preheating roll, and then the surface temperature is 95 ° C. It extended | stretched 3 times between the extending | stretching rolls set to (3). Thereafter, the longitudinally stretched film was forcibly cooled by a cooling roll set at a surface temperature of 25 ° C. The surface temperature of the film before cooling was about 70 ° C., and the surface temperature of the film after cooling was about 25 ° C. The time required for cooling from 70 ° C. to 25 ° C. was about 1.0 second, and the film cooling rate was 45 ° C./second.

  Then, the cooled film is guided to a tenter (second tenter), heat-treated in an atmosphere of 95 ° C. for 2.0 seconds in the second tenter, cooled, and both edges are cut and removed. A film roll made of a heat-shrinkable polyester film was obtained by continuously forming a biaxially stretched film of about 30 μm over a predetermined length.

<Preparation of package with label attached>
The film roll obtained as described above is slit to a width of about 200 mm, and is then divided into a predetermined length to be wound up to create a small slit roll. Label printing (three-color printing) was repeatedly performed using grass, gold, and white inks from K.K. For each label printing, perforations over the entire width of the film (perforations in which circles of about 1 mm in diameter are continuous at intervals of about 4 mm) are arranged at intervals of about 22 mm in a direction perpendicular to the longitudinal direction of the film roll. Two were formed in parallel. Then, one end of the roll-shaped film on which the printing for the label is applied is applied on a part of the outer periphery of a 500 ml PET bottle (bottle diameter 62 mm, neck portion minimum diameter 25 mm). In this state, the roll-shaped film was drawn out by a predetermined length and wound around the outer periphery of the PET bottle. After that, the outer periphery of the PET bottle was coated with a label by fusing and sealing the heat-shrinkable films overlapped on the outer periphery of the PET bottle with a fusing seal blade adjusted to about 240 ° C. Then, using a steam tunnel (model: SH-1500-L) manufactured by Fuji Astec Inc, the PET bottle covered with the label was passed under conditions of a passage time of 2.5 seconds and a zone temperature of 80 ° C., and 500 ml of PET The label loading was completed by heat shrinking the label at the outer periphery of the bottle. At the time of mounting, the neck portion was adjusted so that a portion with a diameter of 40 mm was one end of the label. And the characteristic of the heat-shrinkable film obtained as mentioned above, a label (before and after mounting | wearing), and a package (PET bottle which mounted | wore the label) was evaluated by the above-mentioned method. The evaluation results are shown in Tables 3 and 4.

[Example 2]
A heat-shrinkable film was continuously produced by the same method as in Example 1 except that polyester 1 and polyester 2 were mixed at a weight ratio of 70:30 and charged into an extruder. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Example 3]
A heat-shrinkable film was continuously produced in the same manner as in Example 1 except that the transverse stretch ratio in the tenter (first tenter) was changed to 5.0 times. The biaxially stretched heat-shrinkable polyester film had a thickness of about 24 μm. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Example 4]
A heat-shrinkable film was continuously produced by the same method as in Example 1 except that the temperature of the intermediate heat treatment in the tenter (first tenter) was changed to 140 ° C. The biaxially stretched heat-shrinkable polyester film had a thickness of about 24 μm. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Example 5]
A heat-shrinkable film was continuously produced by the same method as in Example 1 except that the temperature of the stretching roll in the longitudinal stretching machine was changed to 92 ° C. and the stretching ratio in the longitudinal direction was changed to 5.0 times. The biaxially stretched heat-shrinkable polyester film had a thickness of about 18 μm. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Example 6]
A heat-shrinkable film was continuously produced in the same manner as in Example 1 except that the temperature of the stretching roll in the longitudinal stretching machine was changed to 92 ° C. and the stretching ratio in the longitudinal direction was changed to 7.0 times. The biaxially stretched heat-shrinkable polyester film had a thickness of about 13 μm. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Comparative Example 1]
The above-described polyester 3 is put into an extruder, melted at 265 ° C., extruded from a T die, wound around a rotating metal roll cooled to a surface temperature of 30 ° C., and rapidly cooled, thereby an unstretched film having a thickness of 360 μm Got. The take-up speed of the unstretched film was the same as in Example 1. Thereafter, the unstretched film is led to a longitudinal stretching machine (first longitudinal stretching machine) in which a plurality of roll groups are continuously arranged, preheated on a preheating roll, and then stretched at a surface temperature of 88 ° C. The film was stretched 2.7 times between rolls. Further, the film stretched in the longitudinal direction is led to a tenter (first tenter) in which a transverse stretching zone and a heat treatment zone are continuously provided, and the transverse stretching zone is at a stretching temperature of 97 ° C. and is transversely stretched at 97 ° C. After stretching 5 times, heat treatment was performed at 125 ° C. in a heat treatment zone. Thereafter, the heat-treated film is guided to a longitudinal stretching machine (second longitudinal stretching machine) in which a plurality of roll groups are continuously arranged, preheated on a preheating roll, and then stretched at a surface temperature of 98 ° C. Longitudinal stretching was again performed 1.5 times between the rolls. Furthermore, the film stretched again in the longitudinal direction is guided to a tenter (second tenter), heat-treated at 85 ° C., cooled, and both edges are cut and removed, whereby a biaxially stretched film of about 35 μm is stretched over a predetermined length. The film was continuously formed to obtain a heat-shrinkable polyester film roll. The surface temperature of the film after heat treatment and before cooling was about 75 ° C., and was cooled to about 25 ° C. in about 2.0 seconds (cooling rate = 25 ° C./second). Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Comparative Example 2]
A heat-shrinkable film was continuously produced by the same method as in Example 1 except that the temperature of the intermediate heat treatment in the tenter (first tenter) was changed to 70 ° C. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

[Comparative Example 3]
By guiding the unstretched film to a tenter and preheating until the film temperature reaches 90 ° C., the film is stretched 8.0 times in the transverse direction at a stretching temperature of 75 ° C. and cooled, and both edges are cut and removed. About 45 μm laterally uniaxially stretched film was continuously formed over a predetermined length to obtain a heat-shrinkable polyester film roll. The surface temperature of the film after heat treatment and before cooling was about 75 ° C., and was cooled to about 35 ° C. in about 2.0 seconds (cooling rate = 20 ° C./second). Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4. In the film of Comparative Example 3, the width direction is the main shrinkage direction, and the longitudinal direction is the direction orthogonal to the main shrinkage direction.

[Comparative Example 4]
A heat-shrinkable film was continuously produced by the same method as in Comparative Example 1 except that the draw ratio at the time of longitudinal stretching again with the second longitudinal stretching machine was 3.0 times. Further, a label was produced by the same method as in Example 1, and the label was attached to the outer periphery of the PET bottle by the same method as in Example 1. And the characteristic of the obtained film, the label before and behind mounting | wearing, and the package was evaluated by the method similar to Example 1. FIG. The evaluation results are shown in Tables 3 and 4.

  As is clear from Table 3, the films obtained in Examples 1 to 6 have high shrinkability in the longitudinal direction, which is the main shrinkage direction, and the shrinkage in the width direction orthogonal to the main shrinkage direction is It was very low. In addition, the films obtained in Examples 1 to 6 all had high solvent adhesive strength, small longitudinal thickness spots, good label adhesion, no shrinkage spots, and good shrinkage finish. . Furthermore, the heat-shrinkable polyester films of Examples 1 to 6 have good perforation-opening properties and a low natural shrinkage rate, so that wrinkles were not generated on the produced film roll. And the packaging body in which the label made of the heat-shrinkable polyester film obtained in each example is packaged has a good perforation opening property of the label, and the label is clean with an appropriate force along the perforation. It was possible to tear.

  On the other hand, the heat-shrinkable film obtained in Comparative Example 1 had an insufficient heat shrinkage rate, had poor label adhesion, and caused shrinkage spots. Moreover, all the heat-shrinkable films obtained in Comparative Example 2 had a high heat shrinkage rate in the film width direction, had poor label adhesion, and caused shrinkage spots. Further, the film obtained in Comparative Example 4 (the main shrinkage direction is the width direction) has a large thermal shrinkage rate in the direction orthogonal to the main shrinkage direction, and has produced shrinkage spots and a large natural shrinkage rate. Wrinkles occurred on the film roll. In addition, the packaging body in which the label made of the heat-shrinkable polyester film obtained in each comparative example is packaged has poor perforation of the label, and the label is torn cleanly with an appropriate force along the perforation. The percentage of things that could not be done was high.

  Since the package of this invention has the outstanding characteristic as mentioned above, it can be used suitably for the use for the packaging of various articles | goods.

It is explanatory drawing which shows the shape of the test piece in the measurement of a right-angled tear strength (In addition, the unit of the length of each part of the test piece in a figure is mm).

Explanation of symbols

  F ・ ・ Film.

Claims (6)

  A package formed by heat-shrinking at least a part of the outer periphery of a label based on a heat-shrinkable film, and a right angle in a direction perpendicular to the main shrinkage direction per unit thickness of the coated label The tear strength is 100 N / mm or more and 300 N / mm or less, The package body in any one of Claims 1-3 characterized by the above-mentioned.   The package according to claim 1, wherein a tensile fracture strength in a direction orthogonal to a main shrinkage direction of the coated label is 100 MPa or more and 300 MPa or less.   The package according to claim 1 or 2, wherein a refractive index in a direction perpendicular to a main shrinkage direction of the coated label is 1.570 or more and 1.600 or less.   The package according to any one of claims 1 to 3, wherein a perforation or a pair of notches is provided along a direction orthogonal to the main shrinkage direction of the coated label.   After stretching an unstretched film at a temperature of Tg + 5 ° C. or more and Tg + 40 ° C. or less at a magnification of 2.5 times or more and 6.0 times or less in a state where both ends in the width direction are held by clips in the tenter, positively After passing through an intermediate zone in which a typical heating operation is not performed, heat treatment is performed at a temperature of 100 ° C. or more and 170 ° C. or less for a time of 1.0 second or more and 10.0 seconds or less, and then the surface temperature of the film is increased. After cooling to 30 ° C. or more and 70 ° C. or less and cutting and removing the clip gripping portions at both edges in the width direction of the film, the length is 2.0 times or more and 5.5 in the longitudinal direction at a temperature of Tg + 5 ° C. or more and Tg + 80 ° C. or less. Before being formed into a label by stretching at a magnification of not more than twice, and then cooling at a cooling rate of 30 ° C./second to 70 ° C./second until the surface temperature of the film becomes 45 ° C. to 75 ° C. Packaging according to any of claims 1 to 4, characterized in that heat-shrinkable film is produced.   The package according to any one of claims 1 to 5, wherein the heat-shrinkable film is a heat-shrinkable polyester film.

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