JP2008006804A - Heat-shrinkable polyester film, method of manufacturing the same, and heat-shrinkable label - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester film excellent in all of the properties of perforation tearableness when labeled, strength at an adhesive part, impact resistance, designedness when mounted to bottles, slipperiness between labels after applied to bottles. <P>SOLUTION: The heat-shrinkable polyester film contains a silicone constituent at least on an outermost layer of one side, has a shrinkage ratio in one direction (y direction) of not less than 20% and less than 85% after immersed in a hot water of 95°C±0.5°C for 10 seconds, a shrinkage ratio in the direction (x direction) orthogonal to it of not less than 0% and not greater than 10%, and a refractive index in the thickness direction (z direction) of less than 1.5400. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film suitable for label applications.

  As a heat-shrinkable film, particularly a heat-shrinkable film for labeling the body of a bottle, a film made of polyvinyl chloride, polystyrene or the like is mainly used. However, with regard to polyvinyl chloride, in recent years, the generation of chlorine-based gas at the time of incineration of discarded vinyl chloride products has become a problem. On the other hand, polystyrene has problems such as difficulty in printing on a polystyrene film. Furthermore, when collecting and recycling PET bottles, it is necessary to separate labels of resins such as polyvinyl chloride and polystyrene at the time of disposal. For this reason, polyester-based heat-shrinkable films that do not have these problems are attracting attention.

  In addition to heat shrinkability, heat-shrinkable polyester film used as a label for bottles has a perforation-cutting property, adhesive strength, impact resistance, and design characteristics when attached to a bottle. There is a demand for slipperiness between labels after the bottles are mounted.

  The perforation cut property is required because a bottle perforation may be provided on the bottle label. When the product bottle is a beverage glass bottle, it is usually refrigerated. In this case, since label opening is performed at a low temperature, there is a problem that unsuccessful opening is likely to occur, and the demand for perforation cutability is high. In patent document 1, in order to improve perforation cut property, the temperature conditions at the time of extending | stretching are optimized in the manufacturing process of a heat-shrinkable polyester-type film. Although the perforation cutting property of the heat-shrinkable polyester film obtained by this method is somewhat improved, it is still insufficient.

  As a heat-shrinkable polyester film excellent in perforation cutability, Patent Document 2 discloses a heat-shrinkable polyester film having a predetermined hot water shrinkage ratio and breaking elongation. However, this heat-shrinkable polyester film is inferior in the strength of the adhesive part at the time of labeling, such as when the PET bottle falls when it is attached as a label, the adhesive part of the label peels off due to impact was there.

  As for impact resistance, known heat-shrinkable films often stretch about 3 to 5 times only in the lateral direction and easily tear in the lateral direction, so the film label is attached to a glass bottle and packed in multiple boxes, When transported for a long distance, there was a problem that the film was torn laterally due to the impact between the glass bottles. In addition, the production method in which only transverse stretching is performed has a problem that productivity is low. As a measure to improve them, there is a method of suppressing the film tearing due to tension by causing not only the stretching in the transverse direction but also the stretching in the longitudinal direction so that the molecular orientation in the longitudinal direction in the film also exists. When stretching is performed, the production speed in the longitudinal direction is also improved. However, as is well known, when the polymer is simply blended and stretched in the longitudinal direction, the shrinkage in the longitudinal direction occurs, so that there is a problem that the design property is deteriorated particularly when it is attached to a square bottle.

  With regard to slipperiness, in beverages sold by vending machines, when polyester film is used as a label, the slipperiness of the label is insufficient, the product does not pass through the passage and does not reach the outlet, A clogging problem such as discharge may occur. In addition, when sold by heating, there is a problem that not only the slipping property is lowered but also blocking of labels occurs. Patent Document 3 discloses a method of laminating a layer having good slipperiness on the film surface, but this is due to post-processing on the film, and the problem of cost remains.

As described above, in the label application for bottles, all of the perforation cutability, the strength of the adhesive part, the impact resistance, the design property at the time of bottle mounting, and the slipperiness between the labels after the bottle mounting when labeling. An excellent heat-shrinkable polyester film has not been obtained so far.
JP 2003-268131 A JP-A-11-207818 JP 2002-196677 A

  In view of the above circumstances, the problems to be solved by the present invention include perforation cutability, adhesive strength, impact resistance, design at the time of bottle mounting, and slipping between labels after bottle mounting. An object of the present invention is to provide a heat-shrinkable polyester film having excellent properties.

In the present invention, at least one outermost layer contains a silicone component, and the shrinkage in one direction (y direction) after being immersed in warm water of 95 ° C. ± 0.5 ° C. for 10 seconds is 20% or more and less than 85%. A heat-shrinkable polyester-based film having a shrinkage rate in a direction perpendicular to it (x direction) of 0% or more and 10% or less and a refractive index in a thickness direction (z direction) of less than 1.5400. .
The heat-shrinkable polyester film of the present invention preferably has a structure in which X layers containing the polyester component M and Y layers containing the polyester component N are alternately laminated. The polyester component M contained in the X layer contains 70 to 99% by mass of polyester A and 1 to 30% by mass of polyester B, and the polyester component N contained in the Y layer contains 70 to 99% by mass of polyester B and 1 to 30% by mass of polyester A. % Is preferably included. Furthermore, it is preferable that the X layer and the Y layer have a structure in which 500 layers or more are alternately stacked.

  The heat-shrinkable polyester film of the present invention has a friction coefficient between the silicone component-containing surfaces of μd ≦ 0.27, and heat in the y direction after being immersed in warm water of 95 ° C. ± 0.5 ° C. for 10 seconds. The shrinkage rate is 50% or more and less than 85%, the solvent adhesive strength between one surface and the other surface is 2.0 N / 15 mm or more, the tear propagation strength is 2.0 N or less, 60 ° C. ± 1 ° C. It is preferable that the breaking strength after being immersed in warm water for 30 minutes is 20 MPa or more.

Furthermore, the heat-shrinkable thermal polyester film of the present invention is applied to at least one surface of a melt-extruded unstretched polyester film or a uniaxially stretched polyester film after applying a coating liquid containing a silicone component and a binder resin component. It is preferable to laminate 0.002 to 0.5 g / m ^{2 of} a layer containing a silicone component on at least one side obtained by further biaxially or uniaxially stretching the coating film.

  Furthermore, another embodiment of the present invention is a heat shrinkable label formed from the above heat shrinkable polyester film.

  According to the present invention, the heat-shrinkable polyester excellent in all of the perforation cutting property, the strength of the adhesive portion, the impact resistance, the design property at the time of bottle mounting, and the slipperiness between the labels after the bottle mounting when the label is formed. A system film is provided. Since the label using the film of the present invention is excellent in perforation cutting properties, even when it is a full bottle label, it is easy to peel off the label even at a low temperature. In addition, the vending machine hardly causes the problem of label breakage when a beverage product in a plastic bottle falls to the outlet. Furthermore, when a film label is mounted on a glass bottle and packed in a plurality of boxes and transported for a long distance, the problem that the film avoids in the lateral direction due to the impact between the glass bottles is reduced. Furthermore, since the friction between containers can be kept low, clogging of goods in the vending machine can be prevented.

  In the present invention, the coefficient of dynamic friction between at least one side of the film is 0.27 or less, and the shrinkage in one direction (y direction) after being immersed in warm water of 95 ° C. ± 0.5 ° C. for 10 seconds is 20% or more and less than 85%. A heat shrinkable polyester system, characterized in that the shrinkage rate in the direction perpendicular to it (x direction) is 0% or more and 10% or less, and the refractive index in the thickness direction (z direction) is less than 1.5400 It is a film.

  The heat shrinkable polyester film of the present invention has a shrinkage rate (warm water heat shrinkage rate) in one direction (y direction) when immersed in warm water at 95 ° C. ± 0.5 ° C. for 10 seconds in a no-load state. The characteristic is 20% or more. If the heat shrinkage rate is less than 20%, the label may not be properly attached to the container due to insufficient heat shrinkage force. The heat shrinkage rate is preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. In particular, when the heat shrinkage rate is 50% or more, it is possible to attach the label very easily even on a difficult part such as a shoulder of a bottle. On the other hand, the upper limit of the heat shrinkage rate is less than 85%, preferably 82% or less, more preferably 80% or less. In particular, when the heat shrinkage rate is less than 85%, the occurrence of label jumping due to the excessively large shrinkage force of the label when the bottle is placed on the bottle for heat shrinkage is extremely suppressed.

  In addition, the heat shrinkable polyester film of the present invention has a shrinkage rate (warm water heat shrinkage rate) orthogonal to the y direction when immersed in warm water at 95 ° C. ± 0.5 ° C. for 10 seconds under no load. In the direction (x direction) to be performed, it is 0% or more and 10% or less, preferably 0% or more and 8% or less, and more preferably 0% or more and 5% or less. If the heat shrinkage rate exceeds 10%, the film may be labeled, and when it is heat-shrinked and attached to a bottle, there is a possibility that vertical shrinkage may occur. If the heat shrinkage rate is less than 0%, the film label is stretched in the vertical direction.

  Here, the hot water heat shrinkage ratio is obtained by measuring the length of the film before and after the dipping treatment, and using the formula of (length before shrinkage−length after shrinkage) / length before shrinkage) × 100 (%). This is the required value. In addition, when measuring the heat shrinkage rate, the film is immersed in water at 25 ° C. ± 0.5 ° C. after being immersed in warm water at a predetermined temperature for a predetermined time so as not to give an excessive heat history to the film. So that the film cools.

  The heat-shrinkable polyester film of the present invention has a refractive index in the thickness direction (z direction) of less than 1.5400, more preferably less than 1.5390. The refractive index is a value that varies depending on the chemical composition of the polyester film, the structure, and the degree of orientation of the polyester molecules (among these, the degree of orientation of the polyester molecules in particular). It has been found that the chemical composition, structure, and degree of orientation of polyester molecules of a heat-shrinkable polyester film having excellent strength can be expressed by the refractive index in the thickness direction. The value of the refractive index in the thickness direction is lower than that of a normal polyester film, and the polyester film having a low refractive index in the thickness direction is random in the thickness direction. It is thought that the ease of tearing of the film is improved because the force is weak and the cohesive force of molecules is weak. The lower limit of the refractive index is a limit value of the refractive index that can be exhibited by the polyester film, and is considered to be about 1.4000. From the viewpoint of industrial productivity of the polyester film, the lower limit is preferably 1.4500, more preferably 1.5000.

  In the heat-shrinkable polyester film of the present invention, the coefficient of dynamic friction between at least one side of the film is μd ≦ 0.27, more preferably μd ≦ 0.25, and further preferably μd ≦ 0.22. If the coefficient of friction exceeds this range, when the film is attached to the bottle as a label, the slipping property of the label is insufficient and the vending machine is clogged, that is, the product does not pass through the passage and does not reach the outlet. Problems such as multiple emissions are likely to occur. Moreover, when it is sold by heating, the slipperiness is not only reduced, but the labels are easily blocked.

  The heat-shrinkable polyester film of the present invention has a solvent adhesive strength between one surface and the other surface of 2.0 N / 15 mm or more, a tear propagation strength of 2.0 N or less, and in 60 ° C. warm water. The breaking strength after immersion for 30 minutes is preferably 20 MPa or more. The heat-shrinkable polyester film having such characteristics is particularly excellent in perforation cutability and the strength of the adhesive part at the time of labeling.

In the present invention, the solvent adhesive strength is a value determined as follows.
Apply 1,3-dioxolane with a width of 2 ± 1 mm slightly inside from the edge of one side of the film (coating amount: 3.0 ± 0.3 g / m ² ). They are bonded together and processed into a tube (processing speed: 10 mm / min). The tube is cut open so that the bonded portion is in the center, and a film-like test piece (n = 10) having a length of 100 mm and a width of 15 mm is cut out so that the bonded portion is in the center. This film-like test piece was set on a tensile tester in which the distance between chucks was set to 50 mm so that the solvent adhesion portion was located in the center of the chucks, and pulled at a temperature of 23 ° C. and a tensile speed of 200 mm / min. A test is performed to measure the peel strength of the bonded portion. This peel strength is the solvent adhesive strength.

  In the present invention, the solvent adhesive strength is preferably 2.0 N / 15 mm or more, more preferably 2.5 to 20 N / 15 mm, and particularly preferably 2.8 to 10 N / 15 mm.

  In the present invention, the tear propagation strength is based on JIS K7128-2 (1998), a film that has been shrunk 10% in advance at 85 ° C. is cut into a length of 51 mm × width of 64 mm, and a light load tear tester is used. The value obtained by measurement.

In the present invention, the tear propagation strength is preferably 2.0 N or less, more preferably 0.2 to 1.9 N, and particularly preferably 0.5 to 1.8 N.

In the present invention, the breaking strength is a value determined as follows.
A film label having a folding diameter of 87.5 mm and a label length of 120 mm is placed on a 250 mL steel can (outer diameter 53 mm, height 133 mm) and immersed in hot water at 80 ° C. for 10 seconds to shrink-fit the label on the can ( About 5% shrinkage). The steel can with the label is immediately transferred into warm water of 60 ° C. ± 1 ° C. and immersed for 30 minutes. A sample is cut out from the label of the steel can, and the film before heat treatment according to JIS-K-7127 (1999) (test piece is type 2. However, distance between chucks: 20 mm, pulling speed: 200 mm / min) A tensile test is performed in a direction perpendicular to the maximum shrinkage direction (namely, the x direction). The test piece has a length of 100 mm (x direction) and a width of 15 mm, and the test conditions are a distance between chucks of 20 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min. The strength when ruptured during the test is defined as the rupture strength.

  In the present invention, the breaking strength after immersion for 30 minutes in warm water of 60 ° C. ± 1 ° C. is preferably 20 MPa or more, more preferably 30 to 200 MPa, and particularly preferably 40 to 150 MPa. .

  The thickness of the heat-shrinkable polyester film of the present invention is preferably 5 to 100 μm, and more preferably 20 to 50 μm.

  In the present invention, the heat-shrinkable polyester film has a y-direction and x-direction shrinkage ratio and a z-direction refractive index within the above ranges after being immersed in the warm water at 95 ° C. ± 0.5 ° C. for 10 seconds. If so, the chemical composition of the specific film and the structure of the film are not particularly limited. Moreover, there is no restriction | limiting in particular about the manufacturing method of the heat-shrinkable polyester film of this invention.

  As an example of a method for producing a heat-shrinkable polyester film having the above-described heat shrinkage rate and refractive index, an X layer containing a polyester component M and a Y layer containing a polyester component N have a structure in which they are alternately laminated. The method of extending | stretching a heat-shrinkable polyester-type film on suitable extending | stretching conditions is mentioned.

  In the heat-shrinkable polyester film having a structure in which the X layer containing the polyester component M and the Y layer containing the polyester component N are alternately laminated, each of the layers that are preferably 500 layers or more constitutes each layer. Since the polyester component has individual properties, it has characteristics that cannot be obtained with a film produced by mixing two polyester components, and can achieve the low refractive index as described above. As a result, the film is particularly excellent in perforation cutability, strength of the bonded portion, and the like.

  First, a polyester film having a structure in which an X layer containing a polyester component M and a Y layer containing a polyester component N are alternately laminated will be described in detail.

  The polyester components M and N can be selected to meet the object of the present invention in any combination as long as they have different thermal characteristics. It is preferable that the difference in glass transition temperature between the polyester components M and N is 3 ° C. or more and 100 ° C. or less, and the difference in heat of crystal fusion is 5 J / g or more and 100 J / g or less. The polyester component M is a crystalline polyester component having a glass transition temperature measured by DSC of −50 ° C. or more and less than 60 ° C. and a crystal melting heat of 5 J / g or more and 100 J / g or less. Is more preferably a substantially amorphous polyester component having a glass transition temperature of 60 ° C. or more and 150 ° C. or less and a heat of crystal fusion of 0 J / g or more and 3 J / g or less. The polyester components M and N as raw materials may be constituted by either a homopolymer or a copolymer, and may be a polyester composition containing two or more kinds of arbitrary polyesters.

  As a preferable combination of the polyester components M and N, the polyester component M includes 70 to 99 mass% of polyester A and 1 to 30 mass% of polyester B, and the polyester component N includes 70 to 99 mass% of polyester B and 1 to 30 mass% of polyester A. It is preferable to contain. Moreover, it is more preferable that the polyester component M contains 73-97 mass% of polyester A and 3-27 mass% of polyester B, and the polyester component N contains 73-97 mass% of polyester B and 3-27 mass% of polyester A. Furthermore, it is most preferable that the polyester component M contains 75-94 mass% of polyester A and 6-25 mass% of polyester B, and the polyester component N contains 75-94 mass% of polyester B and 6-25 mass% of polyester A.

The polyester components M and N are preferably used in a mass ratio (polyester component M / N) of 97/3 to 3/97. If the mass ratio is outside this range, it is difficult to form a layer structure, and it may be difficult to simultaneously achieve a thermal shrinkage rate of 50% or more and a tear propagation strength of 2.0 N or less at 95 ° C. is there.
Furthermore, the polyester components M and N are more preferably used in a mass ratio (polyester component M / N) of 90/10 to 10/90, and 85/15 to 60/40 or 40/60 to 15/85. Most preferably, it is used in

  Here, examples of the polyester A include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polypentamethylene terephthalate, polyhexamethylene terephthalate, polyethylene-2,6-naphthalate (PEN). ) And other crystalline polyesters can be used. Further, based on these, an acid component and / or a glycol component described later may be copolymerized with 10 mol% or less in 100 mol% of the acid component and / or glycol component. Furthermore, based on polyethylene terephthalate (PET), dimer acid is copolymerized to 10 mol% or less (PET-D), or polyethylene-2,6-naphthalate (PEN) is copolymerized to 10 mol% or less of isophthalic acid. It is also possible to use. More preferred are PBT, PTT and PET-D.

As polyester B, for example, based on a polyester comprising terephthalic acid as an acid component and ethylene glycol as a glycol component, 5 mol% or more, preferably 6 mol% or more and 40 mol% in 100 mol% of the acid component and / or glycol component. A copolymer obtained by copolymerizing less than the different dicarboxylic acid components and / or glycol components can be used. Specific monomer components include, for example, dicarboxylic acid components such as aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, and orthophthalic acid, and aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. And alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Examples of the glycol component include aliphatic diols such as propanediol, butanediol, neopentylglycol, and hexanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, and aromatic diols.
Polyester B is preferably copolymerized with 7 mol% or more and 35 mol% or less neopentyl glycol and / or 1,4-cyclohexanedimethanol, based on polyester comprising terephthalic acid as the acid component and ethylene glycol as the glycol component. Polyester.

The heat-shrinkable polyester film has a structure in which X layers and Y layers are alternately laminated. The number of laminated X layers and Y layers is 500 or more in total of the X layers and Y layers. It is preferable to be, more preferably 1000 to 100,000, and most preferably 2000 to 20,000. When the total of the X layer and the Y layer is 500 layers or more, the perforation cut property is particularly excellent.
The outermost layer of the heat-shrinkable polyester film may be either the X layer or the Y layer.

  For the X layer and Y layer, conventionally known additives, for example, organic particles (eg, crosslinked acrylic particles, crosslinked styrene particles, silicone particles, etc.), inorganic particles (eg, silica, kaolin, clay, carbonic acid) Calcium, aluminum oxide, barium sulfate, zinc oxide, zinc sulfide, etc.), lubricants, stabilizers, colorants, antioxidants, antifoaming agents, antistatic agents, ultraviolet absorbers, and the like.

The heat-shrinkable polyester film used in the present invention preferably has a melting specific resistance value at a temperature of 275 ° C. of 0.70 × 10 ⁸ Ω · cm or less. When such a film is used, as will be described in detail below, the uniformity of the film thickness can be improved, and the printability on the film and the workability when processing the film into a form that can be mounted on a container. (Stable workability) can be improved.

  That is, in the present invention, when the film melt-extruded from the extruder is cooled by a conductive cooling roll (such as a casting roll), an electrode is disposed between the extruder and the casting roll, and the film is interposed between the electrode and the casting roll. A voltage is applied (that is, electricity is applied to the film from the electrode), and the film is electrostatically adhered to the roll. When the melting specific resistance value is small, the adhesion (electrostatic adhesion) between the film and the roll can be enhanced. If the electrostatic adhesion to the roll is low, the thickness of the cast unstretched film becomes non-uniform, and in the stretched film obtained by stretching this unstretched film, the thickness non-uniformity is further expanded. If the electrostatic adhesion is sufficiently high, the stretched film can be made uniform in thickness.

  When the uniformity of the film thickness is increased, color misregistration can be prevented and printability can be improved when multicolor printing in which a plurality of colors are superimposed is applied to the film.

  Next, the manufacturing method of the heat-shrinkable polyester film of the present invention including the manufacturing method of the polyester film having a structure in which the X layer and the Y layer are alternately laminated will be described. Although there is no restriction | limiting in particular in the manufacturing method of the heat-shrinkable polyester film of this invention, For example, polyester component M containing 70-99 mass% of polyester A and 1-30 mass% of polyester B, and 70-99 mass% of polyester B, and polyester A polyester component N containing A1 to 30% by mass is charged into separate extruders E and F, respectively, and melted polyester components M and N are charged into a laminating apparatus to obtain a laminate of polyester components M and N. The laminated body is discharged from the laminating apparatus, and is extruded to a cooling roll to obtain an unstretched sheet. The unstretched sheet is stretched in the transverse direction from 3.0 times to 6.0 times at 60 ° C to 120 ° C, Obtained by a method of stretching in the longitudinal direction from 1.01 to 3.0 times at 50 ° C. or more and 120 ° C. or less before or after stretching in the transverse direction. It is possible.

The heat-shrinkable polyester film of the present invention is a preferred embodiment in which an easy-slip layer is laminated on the surface of the heat-shrinkable polyester film on at least one side of the film.
A material containing a silicone component and a resin component is recommended as the slippery layer.
Silicone components refer to organosiloxanes and have properties such as oil, rubber, and resin, which are called silicone oil, silicone rubber, and silicone resin, respectively. Since it has water repellent action, lubrication action, release action, etc., it is effective in reducing surface friction when laminated as a film surface layer, and also has the effect of preventing blocking between films due to its release properties. can get. Furthermore, when used as a beverage container label, it is often shrunk and attached using steam or hot air, and if it is a slippery layer with low water resistance, the slipperiness using the above will significantly reduce slipperiness. However, due to the water-repellent effect of silicone, good slipperiness can be maintained even after treatment with steam. In particular, silicone resins and silicone copolymers are recommended. Silicone resin refers to organopolysiloxane having a three-dimensional network structure, and when it is laminated as a slippery layer on the polyester film surface and then wound up as a roll, transfer to the back surface of the film is less likely to occur. . Moreover, when using as a drink label, although a printing process is given, the printability in that case is favorable. Furthermore, those having a methyl group as an organic group are particularly recommended because they have excellent heat resistance and are suitable for use as labels for hot beverage containers.
The content is preferably 10 to 80% by weight, particularly preferably 20 to 70%, as the existing amount in the slippery layer. If the abundance is less than 10% by weight, the effect of improving the slipping property is small, and if it exceeds 80% by weight, the transfer of the coating layer component tends to occur.

Silicone and other lubricants may be used in combination. The lubricants used in combination are paraffin wax, micro wax, polypropylene wax, polyethylene wax, ethylene acrylic wax, stearic acid, behenic acid, 12-hydroxystearic acid, stearin. Acid amide, oleic acid amide, erucic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, butyl stearate, stearic acid monoglyceride, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate , Siloxane, higher alcohol polymer, stearyl alcohol, calcium stearate, zinc stearate, magnesium stearate, lead stearate, etc. Is preferred. Among these, the addition of low molecular weight polyethylene wax can be expected to improve lubricity from the effect of preventing sticking by smoothing the layer surface.
Also, inorganic particles such as silica, titania, mica, talc, calcium carbonate, organic particles such as polymethyl methacrylate (PMMA), styrene-divinylbenzene, formaldehyde resin, silicone resin, polyamideimide, benzoguanamine, or the surface thereof Although the slipperiness can be further improved by adding a treated product or the like, the transparency of the film tends to decrease due to the formation of surface irregularities, etc., so the addition amount is appropriately adjusted according to the requirement for transparency. It is recommended.

Examples of the resin component include polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, acrylic resins, polyvinyl acetate resins, polyolefin resins such as polyethylene or polypropylene, cellulose resins, There are melamine resins, copolymers or modified resins thereof, and those that are curable by heat and light energy. Especially, polyester resins, polyurethane resins, or copolymers thereof should be combined with a lubricant. In addition to showing good lubricity, it is recommended because it can be bonded with a solvent in tube processing. Furthermore, from the viewpoint of safety and environmental friendliness, it is preferable to use an aqueous dispersion. This resin component has an effect as a binder and improves the adhesion of the slippery layer to the film. In addition, when the film is stretched after the slippery layer is laminated, the resin component is used as a stretching aid for making a smooth surface. It also has a function. Furthermore, when stretched, it is also effective in strengthening the surface layer.

As a method for forming the slippery layer, a method of laminating a slippery resin on the surface layer by melt extrusion, application of a slippery coating solution during the film forming process (in-line coating), slippery coating after film formation Liquid coating (off-line coating), etc., but in-line coating is expected because of the cost and stretching heat treatment after coating, so that the adhesion between the coating layer and the film is improved and the layer is further toughened. The reverse roll method, the air knife method, the fountain method, etc. are mentioned as examples.
For the coating process, after the polyester-based raw material composition is formed into a film by a melt extrusion method or the like, or after the film-shaped material is stretched uniaxially, the above-described easy-sliding coating solution is smoothed on the film surface. It is preferable to apply to a uniform thickness. After this, it is recommended that the coating layer itself be stretched following the film by heating and stretching in a uniaxial or biaxial direction, so that the effect of improving adhesion and toughness to the film can be obtained. The

  As an embodiment of the present invention, a polyester resin, a polyurethane resin, an acrylic resin or a copolymer thereof is used as a binder resin component, a silicone resin or a silicone copolymer resin is used as a lubricant, and heat shrinkage is performed by an inline coating method. It is particularly recommended to form a slippery layer on the surface layer of the conductive polyester film.

The amount of the coating layer present on the film after stretching and drying is preferably 0.002 to 0.5 g / m ² , more preferably 0.003 to 0.2 g / m ² . If it is 0.002 g / m ² or less, the frictional resistance becomes large, and if it exceeds 0.5 g / m ² , the transparency of the film is lowered, the adhesiveness with a solvent is lowered, and the roll in the processing step, etc. And wear debris is generated due to rubbing of the laminated surface.

  The heat-shrinkable polyester film thus obtained has a shrinkage rate in one direction (y direction) of 20% or more and less than 85% after being immersed in warm water of 5 ° C. ± 0.5 ° C. for 10 seconds, The shrinkage rate in the direction perpendicular to it (x direction) is 0% or more and 10% or less, and the rate in the thickness direction (z direction) is less than 1.5400. Further, the solvent adhesive strength is 2.0 N / 15 mm or more, the tear propagation strength is 2.0 N or less, and the breaking strength after being immersed in warm water at 60 ° C. ± 1 ° C. for 30 minutes is 20 MPa or more. Have. And when it is made into a label, it is excellent in all of the perforation cut property, the strength of the adhesive part, the impact resistance, the design property at the time of bottle mounting, and the slipperiness between labels after the bottle mounting, and is suitable as a label for a bottle. .

  In the present invention, the perforation cut property refers to the ease of tearing by a finger in the perforation provided in the vertical direction for the purpose of easily removing the label film attached to the bottle from the bottle. It refers to the ease of tearing at the fingertips of the perforations on the bottle label immediately after refrigeration at 5 ° C. for 12 hours and taking out from the refrigerator. Excellent perforation cutability means that when the perforation is torn with a finger, the film is damaged and the film part pinched by the fingertip is torn or the film is torn in a direction not along the perforation. Rather, it refers to tearing easily in the direction in which the perforations are formed.

  The strength of the bonding part is the difficulty of peeling off the part where the film is laminated and bonded when the film is made into a cylindrical shape, especially against the impact when the bottle with the film label is dropped. When the bottle with the film label is freely dropped from a height of 1 m onto the concrete surface, the adhesive part is not dissociated and the film is not damaged at the adhesive part.

  Impact resistance refers to the impact resistance against impacts between glass bottles, especially when film labels are mounted on glass bottles and packed in multiple boxes and transported over long distances. This means that the film does not break (especially in the lateral direction) against a strong impact.

  Designability when a bottle is attached refers to the appearance of the film label attached to the bottle, and excellent designability means that a cylindrical film attached to a bottle (especially a square bottle). It means that the label hardly causes vertical draw and the upper edge and the lower edge of the film label are almost horizontal. In addition, the vertical shrinkage means that the lengths in the vertical direction of the labels after shrinkage are not uniform, and the upper edge of the label after being shrunk on a PET bottle or the like draws a line that curves downward, An appearance defect in which the edge draws a curved line upward.

  The labeling of the heat-shrinkable polyester film of the present invention can be performed by a conventionally known method. As an example, a heat-shrinkable polyester film cut to a desired width is appropriately printed, and the right and left ends of the film are overlapped and bonded together by solvent adhesion or the like to produce a tube film. The tube film is cut into an appropriate length to obtain a tube-shaped label. Alternatively, one opening of this tubular label is joined to form a bag-like label.

  These labels are perforated by a conventional method, and then covered with a plastic bottle. The plastic bottle is placed on a belt conveyor or the like, and steam is blown into a contracting tunnel (steam tunnel) or hot air is blown. Pass the inside of the type of shrinking tunnel (hot air tunnel). The label is attached to a bottle container such as a plastic bottle by the thermal contraction of the label when passing through these tunnels.

Specifically, an example in which the heat-shrinkable polyester film of the present invention is labeled and attached to a 500 mL PET bottle is shown by using a tube forming device, and a little inside 1,3 from the edge of one side of one end of the film. -Dioxolane is applied in a width of 2 ± 1 mm (application amount: 3.0 ± 0.3 g / m ² ). Immediately roll up the film and glue the ends together to create a tubular film label. The size of the tube-shaped film label may be any size as long as it can be attached to a 500 mL plastic bottle without wrinkles. As a measure of the size of the film label, the folding diameter is 109 mm and the label length is about 90 mm.

  Perforations according to the actual product form are provided on the label. For example, using a sewing machine blade, holes having a length of 0.2 to 2.0 mm are disposed at intervals of 0.2 to 1.0 mm along a direction perpendicular to the main contraction direction of the label, and extend over the entire length of the label. One or two perforations of length are provided.

  Subsequently, the film is coated on a 500 mL PET bottle (round shape, body diameter 62 mm, minimum neck diameter 25 mm), and a steam tunnel is used to pass the tube-shaped film label through a passage time of 2.5 seconds and a zone temperature of 80. By heat shrinking at 0 ° C., it can be attached to a 500 mL PET bottle.

  And the said label is excellent in all of the perforation cut property, the strength of an adhesive part, impact resistance, the design property at the time of bottle mounting, and the slipperiness between labels after bottle mounting.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited to these Examples at all. First, the evaluation method of the film created in the Example and the comparative example is demonstrated.

(1) Friction coefficient The dynamic friction coefficient μd between film surfaces was measured in an environment of 23 ° C. and 65% RH in accordance with JIS K-7125.
Further, after the hot water treatment, the film was subjected to treatment in 80 ° C. hot water for 20 seconds, and the film was shrunk by 10% in the main shrinkage direction was measured by the same method as described above.

(2) Heat Shrinkage The film was cut into a 10 cm × 10 cm square, and heat-shrinked in warm water at 95 ° C. ± 0.5 ° C. for 10 seconds under no load. The film was immediately immersed in water at 25 ° C. ± 0.5 ° C. for 10 seconds, then the vertical and horizontal dimensions of the film were measured, and the thermal shrinkage rate was determined according to the following formula (1). The direction in which the thermal contraction rate is large was taken as the y direction.
Thermal shrinkage rate = ((length before shrinkage−length after shrinkage) / length before shrinkage) × 100 (%) (1)

(3) Solvent adhesive strength 1,3-Dioxolane was applied in a width of 2 ± 1 mm from the edge of one side of one end of the film in a width of 2 ± 1 mm (application amount: 3.0 ± 0.3 g / m ² ). Immediately after the film was rolled, the ends were superposed and bonded, and processed into a tube (processing speed: 10 mm / min). The tube was rolled up in a flattened state to form a roll.
The tube-shaped sample cut out from the roll-shaped material was cut open so that the adhesion location was in the center, and used as a film-shaped sample. From this film-like sample, a film-like test piece (n = 10) having a length of 100 mm and a width of 15 mm was cut out, and this film-like test piece was set to a tensile tester (made by Baldwin, " STM-T ") is set so that the solvent adhesion part is located at the center of the chucks, a tensile test is performed at a temperature of 23 ° C and a tensile speed of 200 mm / min, and the peel strength of the adhesion part is measured. This was defined as solvent adhesive strength.

(4) Tear Propagation Strength Based on JIS K7128-2 (1998), a film preliminarily shrunk at 85 ° C. by 10% was cut into 51 mm length × 64 mm width, and a light load tear tester manufactured by Toyo Seiki Seisakusho Co., Ltd. The value obtained was used as the tear propagation resistance.

(5) Perforation cut test Three colors were printed on a heat-shrinkable film in advance with grass, gold, and white ink from Toyo Ink Mfg. Co., Ltd. A tube-shaped label was prepared by adhering both ends of the printed film with 1,3-dioxolane. The label size was a folding diameter of 109 mm and a label length of 90 mm.
The label was perforated in a direction perpendicular to the main shrinkage direction of the label. Two sheets of cardboard with a thickness of 1 mm are placed under the folded label, and a sewing machine blade (a blade with a total length of 100 mm with 1 mm pitch blades spaced at 1 mm intervals) is placed on a test sealer (made by Seibu Kikai Co., Ltd.). Attach, press the sewing machine blade to the label with a gauge pressure of 2 kg / cm ² , and put a perforation parallel to the label edge at a position 5 mm from the edge of the folded label. The label was provided with two perforations provided with holes of 1 mm in length at intervals of 1 mm over the entire length of the label, and the interval between the two perforations was 10 mm.
Using a steam tunnel (model: SH-1500-L) manufactured by Fuji Astec Inc., spraying steam with a vapor pressure of 98 kPa (pressure gauge display: 1 kg / cm ² ) at a transit time of 2.5 seconds and a zone temperature of 80 ° C. (display). The label was heat-shrinked and attached to a 500 mL PET bottle (round shape, trunk diameter 62 mm, minimum neck diameter 25 mm). At this time, a portion (shoulder portion) having a diameter of about 40 mm was set to one end of the label.
After that, this bottle is filled with about 500 mL of water, refrigerated at 5 ° C. for 12 hours, tearing the perforation of the label on the bottle immediately after taking it out of the refrigerator with a fingertip, and tearing it off vertically to remove the label from the bottle The number of bottles formed was counted, and the percentage of bottles that could not tear the label cleanly for all 50 samples was shown as the perforation cut defect rate (%).

(6) Breaking at the time of dropping A plastic bottle that had been attached with a label under the condition (5) and refrigerated at 5 ° C. for 12 hours was free-dropped onto a glossy concrete surface by applying a dust-proof coating from a height of 1 m. At this time, holding the PET bottle sideways and releasing it, the bottle dropped from its side surface onto the concrete surface. A test was performed on 10 PET bottles. If even one bonded part was removed, it was rated as x. Further, whether or not the perforation part was torn was evaluated in the same manner.

(7) Breaking strength A film label having a folding diameter of 87.5 mm × label length of 120 mm is placed on a 250 mL steel can (outer diameter 53 mm, height 133 mm) and immersed in 80 ° C. hot water for 10 seconds to remove the label. The can was contracted and mounted (approximately 5% contraction). The steel can with the label attached was immediately transferred into warm water of 60 ° C. ± 1 ° C. and immersed for 30 minutes. A sample was cut out from the steel can label (the part without back attachment) and JIS-K-7127 (1999) (the test piece was type 2. However, the distance between chucks: 20 mm, the pulling speed: 200 mm / min) A tensile test was conducted in the direction orthogonal to the maximum shrinkage direction of the film before heat treatment. The test piece has a length of 100 mm (direction perpendicular to the maximum shrinkage direction of the film) and a width of 15 mm. Test conditions are a distance between chucks of 20 mm, a temperature of 23 ° C., and a tensile speed of 200 mm / min. The strength at the time of breaking during the test was defined as the breaking strength.

(8) Refractive index Samples obtained by cutting out the films obtained in Examples and Comparative Examples to have a width of 2 cm and a length of 3 cm were used as samples. At this time, a sample was prepared by cutting out such that the length direction of the sample was parallel to the length direction of the film (longitudinal stretching direction; x direction).
About each said sample for a measurement, the refractive index of the length direction of a film, the width direction (lateral stretching direction; y direction), and the thickness direction (z direction) was measured using the Abbe refractometer 4T made from an Atago optical company. The solvent used for the measurement was diiodomethane, and the measurement conditions were 23 ° C. and 60 RH%. The number of measurements was n = 5.

(9) Film breakage due to impact in glass bottle Glass bottle filled with 140 mL of water (60 ° C.) with a film label of folding diameter 86.0 mm × label length 60.0 mm [height 125 mm (inner body part 83 mm), The label was shrunk and attached to the bottle by immersing it in hot water at 80 ° C. for 10 seconds. At this time, of the label length of 60.0 mm, 10.0 mm was attached so as to cover a portion thinner than the shoulder of the bottle (portion inclined toward the tip of the bottle at the shoulder). The bottle with the label was immersed in 30 ° C. water for 12 hours and cooled. Furthermore, it was allowed to cool for 12 hours in an atmosphere of −5 ° C. One set of a dozen bottles packed in a box of 3 in the vertical direction and 4 in the horizontal direction was taken as one set, and 20 sets were prepared. The number of damaged films after counting 20 sets on a truck and running 500 km was counted.

(10-1) Number of layers inside the film (part 1)
The number of layers inside the film was determined by observation using a transmission electron microscope. First, the film was embedded in an epoxy resin. As the epoxy resin used, a mixture of Luabeck 812, Luavec NMA (manufactured by Nacalai Tesque) and DMP30 (manufactured by TAAB) in a ratio of 100: 89: 3 was used. Next, after embedding the sample film in the above-described mixed resin, the sample film was left in an oven adjusted to a temperature of 60 ° C. for 16 hours to cure the resin and obtain an embedded block.
The obtained embedding block was attached to an ultra cut N manufactured by Nissan Sangyo Co., Ltd. and an ultrathin section was prepared. First, trimming was performed using a glass knife until a cross section of a portion desired to be observed for the film appeared on the resin surface. Next, an ultrathin section was cut out using a diamond knife (Sumitomo Electric Sumiknife SK2045). The cut sections were collected on a mesh and then stained by standing in a ruthenium tetroxide vapor for 30 minutes at room temperature, followed by thin carbon deposition.
The electron microscope observation was performed using JEM-2010 manufactured by JEOL under the condition of an acceleration voltage of 200 kV. The obtained image was recorded on an imaging plate (FDL UR-V manufactured by Fuji Photo Film). The signal recorded on the imaging plate is read out using digital luminography (Pixsys TEM manufactured by JEOL), recorded as digital image information on a Windows personal computer, and the layer confirmed from the difference in staining degree between the X layer and the Y layer I counted the number.
(10-2) Number of layers inside film (part 2)
The number of layers inside the film was determined by observation using a transmission electron microscope (TEM). First, the film was embedded in an epoxy resin. As the epoxy resin used, Luabeck 812, Luavec NMA (manufactured by Nacalai Tesque), and DMP30 (manufactured by TAAB) were mixed well at a ratio (mass) of 100: 89: 3, respectively. Next, after embedding the sample film in the above-described mixed resin, the sample film was left in an oven adjusted to a temperature of 60 ° C. for 16 hours to cure the resin and obtain an embedded block.
The resin was cut with respect to the embedded block using a glass knife until the cross section of the film portion appeared on the block surface (surface exposure). The embedding block after the surface exposure was put in a vessel sealed with ruthenium chloride vapor for 3 days to carry out ruthenium staining. Ruthenium chloride vapor was replaced with fresh vapor every day.
A number of ultrathin sections having a thickness of about 700 mm with a microtome were cut from the surface of the embedded block to about 1.5 μm from the surface of the embedded block. The ultra-thin slice with the clearest contrast was selected and subjected to carbon deposition to obtain a sample for TEM observation.
The electron microscope observation was performed using JEM-2010 manufactured by JEOL Ltd. under the condition of an acceleration voltage of 200 kV. The obtained image was recorded on an imaging plate (“FDL UR-V” manufactured by Fuji Photo Film Co., Ltd.). The signal recorded on the imaging plate was read out using digital luminography (“Pixsys TEM” manufactured by JEOL Ltd.) and recorded as digital image information on a Windows (registered trademark) personal computer. The magnification was appropriately selected from 5000 to 20000 times.
The image information was analyzed using image analysis software (Scion Image Alpha 4.0.3.2; manufactured by Scion Corporation). First, preliminary confirmation was performed before confirming the detailed number of layers. The preliminary confirmation was performed as follows.
1. The color density in the film thickness direction was quantified by a line profile. Specifically, the density of 100 pixels in width and 3000 pixels in length (the number of pixels can be changed arbitrarily) is read, and the curve is drawn with the horizontal axis as the pixel in the length direction and the vertical axis as the signal intensity (darkness). And graphed.
2. Since there are many peaks in the curve in the graph, for one peak, the number of pixels at the position where the maximum value exists and the number of pixels at the position where the minimum value exists are read, and the difference d (peak width) About half) was considered the thickness of the layer. About 30 peaks, d was calculated _| required and average value _dav was calculated.
3. The average value d _av was converted into nm units, and when the converted value was 100 nm or more, the number of layers was counted visually from the TEM image on the imaging plate. In the conversion, when the TEM image is 5000 times, one pixel is 5 nm, and when it is 20,000 times, one pixel is 1.25 nm.
4). When d _av (nm) after the above conversion was less than 100 nm, the following detailed layer number confirmation method was adopted to determine the number of layers.
A detailed method for confirming the number of layers was performed as follows.
1. About the said TEM observation image, the correction process with the noise and the unevenness of the shade of an image was performed. First, the image was captured using image analysis software (L Process ver. 1.96; manufactured by FUJIFILM Science Lab99) (FIG. 3). With the setting of the image selector tool set to 2 ⁿ , Fourier transform (FFT) was performed in the maximum range of the image (2048 × 2048 pixels, but can be arbitrarily specified) (FIG. 4). In FIG. 3, the center of the figure is determined, the layer direction (stripe direction) is taken as the X axis, and the direction orthogonal to the direction is taken as the Y axis. In FIG. 4, the center of FIG. 3 and the center of FIG. 4 (zero pixel) are arranged so that the collection of white bright spots is along the Y axis (in the figure, horizontal and vertical lines are visible, which is noise). In addition, the 5th pixel to the 1020th pixel on the Y axis were surrounded by a rectangle having a width of 200 pixels (from −100 pixel to + 100th pixel on the X axis). Similarly, the rectangle from the -5th pixel to the -1020th pixel was surrounded by a rectangle having a width of 200 pixels. The areas other than those enclosed are treated as noise. The numerical values of 5 to 1020 pixels and the width of 200 pixels are empirically derived values for removing noise. Only the enclosed part was subjected to inverse Fourier transform (IFFT), and the obtained image was saved in TIFF format (16 bits) (FIG. 5).
2. The image after inverse Fourier transform was read into image analysis software (Scion Image Alpha 4.0.3.2; manufactured by Scion Corporation), and the density of the image was clarified by the Threshold function and changed to the BMP format (FIG. 6). (End of correction process)
3. In this BMP format image, using the Profile Plot function, a line profile that is as long as possible (about 2000 to 2500 pixels) parallel to the Y axis is taken with a plot width of 1 pixel, so that the density of the film cross-sectional image is binarized. And saved in Plot Value format.
4). This Plot Value format data was read into Microsoft Excel, and the average value (Av) of all the data for each pixel of the line parallel to the Y axis was obtained. Next, when the data of a certain pixel is larger than the average value (Av), the judgment value +1 is given to the pixel, and otherwise, the judgment value -1 is given to the pixel. When the judgment value of each pixel is plotted with respect to the pixel (horizontal axis), the obtained graph is a horizontal straight line connecting +1 and +1 (or -1 and -1), +1 and -1 (or vice versa). It became a line consisting of diagonal straight lines connecting The number of diagonal lines was determined as the number of layers.
The number of layers obtained by the above method may be smaller than the 2 ⁿ layer or 2 ^{n + 1} layer theoretically obtained from the number n of elements of the static mixer. The polyester resin component M constituting the X layer and the polyester resin component N constituting the Y layer have a different resin composition, but transesterification occurs at the interface between adjacent layers during the lamination process, and the X layer and the Y layer. A polyester having the same composition may be formed in the vicinity of the interface. For example, if the number of layers is increased and the thickness of one layer is reduced to a level of several nanometers, it is identified that a part of the X layer and the Y layer are layers of the same polyester composition. It is considered to be smaller than the theoretical value when the confirmation method is adopted.
The number of layers is the number of layers inside the base film, excluding the easy-sliding layer.

(11) Blocking test under high temperature The sample was attached to a 350 mL heated plastic bottle (square 58 mm x 58 mm, minimum neck diameter 24 mm) so that the easy-to-slip surface of the label would be the outer surface under the conditions of (5). . The PET bottle beverage was laid down and stacked in five layers, and the presence or absence of blocking after lapse of 7 days at 75 ° C. was evaluated.

(12) Vending machine clogging test Under the conditions of (5), a 500 mL PET bottle (square 58 mm x 58 mm, minimum neck diameter 25 mm) was mounted so that the easy-to-slip surface of the label would be the outer surface. When 400 bottles of this plastic bottle beverage were put into the vending machine and discharged, the number of cases where clogging or multiple discharge occurred was counted.

(Preparation of coating solution)
The solid content of an aqueous dispersion of silicone / acrylic acid ester copolymer (Charine NS-626, manufactured by Nissin Chemical Industry Co., Ltd.) is 70% by mass in the total solid content of the coating liquid, and the aqueous dispersion of the acrylic acid ester copolymer is dispersed. The liquid (Vinibran 2585 Nissin Chemical Industry Co., Ltd.) has a solid content of 20 mass% in the solid content, the acetylene glycol derivative (Surfinol 486 manufactured by Air Products Japan) has a solid content of 10 mass% in the solid content, and isopropyl alcohol is 20 mass%. 100 kg of an aqueous solution containing was added to the tank.

(Synthesis of polyester)
In an esterification reactor, 57036 parts by mass of terephthalic acid (TPA), 33244 parts by mass of ethylene glycol (EG), 15733 parts by mass of neopentyl glycol (NPG), 23.2 parts by mass of antimony trioxide (polymerization catalyst) , 5.0 parts by weight of sodium acetate (alkali metal compound) and 46.1 parts by weight of trimethyl phosphate (phosphorus compound), adjusted to 0.25 MPa, and stirred at a temperature of 220 to 240 ° C. for 120 minutes to form an ester The reaction was carried out. The reaction vessel was returned to normal pressure, and 3.0 parts by mass of cobalt acetate tetrahydrate and 124.1 parts by mass of magnesium acetate tetrahydrate (alkaline earth metal compound) were added. After stirring for 5 minutes, the pressure was reduced to 0.5 hPa over 75 minutes and the temperature was raised to 280 ° C. Stirring was continued until the melt viscosity reached 4500 poise at a temperature of 280 ° C. (about 70 minutes), and then discharged into water in the form of a strand. A polyester chip A was obtained by cutting the discharged material with a strand cutter. The intrinsic viscosity of the polyester chip A was 0.75 dl / g.
By the same method, the polyester raw material chip | tip B of the chip | tip composition shown in Table 1 was obtained. In the tables, PD is 1,3-propanediol, CHDM is 1,4-cyclohexanedimethanol, BD is 1,4-butanediol, and DIA is an abbreviation for dimer acid. The intrinsic viscosity of the polyester chip B was 0.92 dl / g.

  The intrinsic viscosity was precisely weighed with 0.1 g of a chip, dissolved in 25 ml of a mixed solvent of phenol / tetrachloroethane = 3/2 (mass ratio), and then measured with an Ostwald viscometer at 30 ± 0.1 ° C. . The intrinsic viscosity [η] is obtained by the following formula (Huggins formula).

Here, η _sp : specific viscosity, t ₀ : solvent dropping time using Ostwald viscometer, t: chip solution dropping time using Ostwald viscometer, and C: concentration of chip solution. In the actual measurement, the intrinsic viscosity was calculated by the following approximate equation where k = 0.375 in the Huggins equation.

Here, η _{r is the} relative viscosity.

Table 1 shows the composition and physical properties of the polyester chips A and B.

Example 1
Each chip obtained in the above synthesis example was separately pre-dried, and as shown in Table 2, 80 kg of chip A and 20 kg of chip B were sufficiently mixed using a super mixer (manufactured by Kawada Seisakusho), and then the mixed pellet was extruded. It was put into a hopper of I (single axis 60 mmφ, L / D = 25) and melted at 275 ° C. ± 2 ° C. Similarly, after 5 kg of chips A and 25 kg of chips B were sufficiently mixed using a super mixer, they were melted at 255 ° C. ± 2 ° C. with an extruder II (a twin screw extruder, 22.5 mm × 2, L / D = 25).

  The resin melted by both extruders is led to a feed block of 265 ° C. ± 2 ° C. so that I / II = 8/2 (discharge mass ratio), and further a static mixer of 275 ° C. ± 2 ° C. (Noritake Company) And 12 elements, inner diameter 38.4 mm, 1 element L / D = 1.5, 1 element plate twist angle 180 degrees). Subsequently, it led to a T-die at 275 ° C. ± 2 ° C. and melt extruded. The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 20 ° C. ± 2 ° C. to obtain an unstretched sheet. Note that the time from when the resin laminate was discharged from the exit of the static mixer at the end of lamination to the close contact with the cooling roll was about 2 minutes. Further, the discharge amount of the extruders I and II was 40 kg per hour.

  The unstretched sheet was preheated with a metal roll having a surface temperature of 75 ° C., and then longitudinally stretched 1.4 times with a silicon rubber roll having a surface temperature of 80 ° C.

  A coating liquid is applied to the stretched film by a fountain die coating / smoothing bar method using a die lip gap of 320 μm, a nozzle gap of 200 μm, and a smoothing bar having a diameter of 8 mm. A coating solution was supplied.

Next, after preheating in a tenter at 82 ° C. for 24 seconds, the film was stretched 4.8 times at 77 ° C. in the transverse direction, followed by heat treatment at 70 ° C. for 24 seconds to obtain a thickness of 45 μm and a coating amount of 0.02 g / A heat-shrinkable polyester film of m ² was obtained. Table 3 shows the physical property values of the obtained film.

Example 2
The solid content of the silicone aqueous dispersion (TSM6343 manufactured by Toshiba Silicone) is 70% by weight in the total solid content of the coating liquid, and the solid content of the aqueous dispersion of acrylate ester copolymer (ViniBran 2583 manufactured by Nissin Chemical Industry) is used. An IPA-water solution containing 20% by weight in solid content and 10% by weight in solid content of acetylene glycol derivative (Surfinol 465, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a coating solution. Otherwise, a heat-shrinkable polyester film was obtained in the same manner as in Example 1. Table 3 shows the physical property values of the obtained film.

Comparative Example 1
In Example 1, a heat-shrinkable polyester film was obtained in the same manner as in Example 1 except that the coating amount was 0.7 g / m ² . Table 3 shows the physical property values of the obtained film.

Comparative Example 2
In Example 1, a heat-shrinkable polyester film was obtained in the same manner as in Example 1 except that the coating solution was not applied. Table 3 shows the physical property values of the obtained film.

Comparative Example 3
Except that chip A and chip B were mixed at 80/20 (weight ratio), put into Extruder II (Twin Screw Extruder), melted at 275 ° C. and led to T-die without using a static mixer In the same manner as in Example 2, a heat-shrinkable polyester film was obtained. Table 3 shows the physical property values of the obtained film.

  In the film obtained in Comparative Example 1, the solvent-adhered portion was peeled off when the film was shrink-fitted to the bottle, and the label could not maintain a cylindrical shape.

  The heat-shrinkable polyester film of the present invention is suitable for bottle labels, and can suppress problems such as the occurrence of clogging particularly when sold with a vending machine.

It is the TEM photograph of the film taken in into image analysis software. FIG. 3 is an image after Fourier transform of FIG. 2. FIG. 4 is an image after the inverse Fourier transform of FIG. 3. It is an image after clarifying the shading of FIG.

Claims (10)

  The coefficient of dynamic friction between at least one side of the film is 0.27 or less, and the shrinkage rate in one direction (y direction) after being immersed in warm water of 95 ° C. ± 0.5 ° C. for 10 seconds is 20% or more and less than 85%, A heat-shrinkable polyester film having a shrinkage rate in a direction perpendicular to it (x direction) of 0% or more and 10% or less and a refractive index in a thickness direction (z direction) of less than 1.5400.   2. The heat-shrinkable polyester film according to claim 1, wherein the X layer containing the polyester component M and the Y layer containing the polyester component N have a structure in which they are alternately laminated.   The polyester component M contained in the X layer contains 70 to 99% by mass of polyester A and 1 to 30% by mass of polyester B, and the polyester component N contained in the Y layer contains 70 to 99% by mass of polyester B and 1 to 30% by mass of polyester A. The heat-shrinkable polyester film according to claim 2.   The heat-shrinkable polyester film according to claim 2 or 3, wherein the X layer and the Y layer have a structure in which 500 layers or more are alternately laminated.   The solvent adhesion strength between the one side and the other side of the film is 2.0 N / 15 mm or more, the tear propagation strength is 2.0 N or less, and the fracture after being immersed in warm water of 60 ° C. ± 1 ° C. for 30 minutes The heat-shrinkable polyester film according to any one of claims 1 to 4, wherein the strength is 20 MPa or more.   The heat-shrinkable polyester film according to any one of claims 1 to 5, wherein an easy-slip layer is laminated on at least one outermost layer of the film.   The heat-shrinkable polyester film according to claim 6, wherein the easy-slip layer contains a silicone component.   The coating solution containing the silicone component is applied to at least one surface of the melt-extruded unstretched polyester film or uniaxially stretched polyester film, and then the coated film is further biaxially stretched or uniaxially stretched. The manufacturing method of the heat-shrinkable polyester film of Claims 1-7 to do. Heat-shrinkable polyester film according to claim 7, the silicone component-containing layer of slipperiness layer is characterized in that it is a 0.002~0.5 g / m ^2.   The heat-shrinkable label produced from the heat-shrinkable polyester-type film in any one of Claims 1-7, 9.