JP2006187886A - Polyester having dead holding properties and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive polyester film excellent in twist holding properties and dead holding properties. <P>SOLUTION: The polyester film having the dead holding properties is composed of a resin composition containing polybutylene terephthalate and polyethylene terephthalate and the resin composition contains 35-65 mass% of polybutylene terephthalate with respect to 100 mass% of the sum total of polybutylene terephthalate and polyethylene terephthalate. The molten resin composition is gradually cooled to be stretched while held to an amorphous state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dead-holding polyester film, and more particularly to a dead-holding polyester film that is excellent in twist holding property and useful as a packaging film.

  In many cases, the packaging film is required to have a dead hold property (a property capable of maintaining a state of being subjected to deformation such as twisting and bending). Conventionally, cellophane, uniaxially stretched polyethylene film, and the like are known as films for twist packaging. Cellophane is excellent not only in dead hold property but also in transparency and easy cutting property. However, since cellophane has hygroscopic property, there is a problem that the physical properties greatly change due to humidity fluctuation. The uniaxially stretched polyethylene film has insufficient dead hold property.

  Therefore, the present condition is that the laminated film which consists of an aluminum foil excellent in dead hold property, and paper and / or a resin film is used for packaging of foodstuffs, tobacco, etc. However, the packaging material having an aluminum foil has a problem that in the incineration process after use, the aluminum foil is entangled as an ingot in the incinerator and damages the incinerator, thereby reducing the incineration efficiency. Moreover, it is difficult to separate only the aluminum foil from the laminated film as described above. Therefore, from the viewpoint of environmental protection, it is desirable not to use a packaging material having an aluminum foil as much as possible. In addition, in the case of instant foods such as cup ramen, from the viewpoint of food safety, it is necessary to inspect whether metallic foreign matter is mixed in the container, but after heat sealing the lid with aluminum foil Since detection by a metal detector is impossible, the current state is that the lid is inspected before heat sealing. In addition, when an aluminum foil is used as the lid, there is a problem that the lid becomes heavy.

  As a lid material not including an aluminum foil, for example, a laminated film having a paper layer / adhesive resin layer / polyethylene terephthalate film layer / easy-peelable resin layer in order is proposed. Polyethylene terephthalate (PET) film has properties such as water vapor barrier properties, dimensional stability against heat, and suitability for filling machines (no curling). However, since PET film has high waist strength, it has poor properties (dead hold property) for keeping the lid open. Therefore, the lid body is easily closed after opening, and there is a problem that it is difficult to pour hot water.

  Japanese Patent Application Laid-Open No. 2004-181563 (Patent Document 1) discloses a polyester resin layer (B) composed of two or more kinds of crystalline polyesters and one or more kinds of amorphous polyesters on at least one surface of the crystalline polyester resin layer (A). Has proposed a stretched polyester film in which is laminated. In Patent Document 1, as the polyester resin (B), 30 to 75% by mass of PET, 5 to 30% by mass of polybutylene terephthalate (PBT), and 20 to 40% by mass of a glass transition temperature of 35 ° C. or more. A polyester resin mixture is described which consists of an amorphous polyester and the sum of PBT and amorphous polyester is 70-25% by weight. However, the stretched polyester film having this twisting property was obtained by laminating the crystalline polyester resin (A) and the polyester resin (B) while extruding each from a separate extruder. Since the laminate was obtained by heat treatment after stretching, and the manufacturing process was complicated, the cost was high.

JP 2004-181563 A

  Accordingly, an object of the present invention is to provide an inexpensive dead-holding polyester film which is excellent in twist holding property and inexpensive.

  As a result of diligent research in view of the above object, the present inventor has melted a resin composition containing polybutylene terephthalate and polyethylene terephthalate at a specific blending ratio, and gradually stretched it while keeping it in an amorphous state. The present inventors have found that a low-priced dead-holding polyester film having excellent twist-holding properties can be obtained, and have arrived at the present invention.

  That is, the dead-holding polyester film of the present invention comprises a resin composition containing polybutylene terephthalate and polyethylene terephthalate, and the resin composition has a polybutylene terephthalate content of 35 to 100% by mass as the total of polybutylene terephthalate and polyethylene terephthalate. The resin composition containing 65% by mass is characterized by being stretched while being gradually cooled and kept in an amorphous state.

  The dead-holding polyester film of the present invention is preferably formed by an air-cooled inflation method in which a tube obtained by extruding the molten resin composition from an annular die is expanded by injecting air. The dead-holding polyester film of the present invention has a haze value of 15% or less and is excellent in transparency. The dead-holding polyester film of the present invention may uniformly form a large number of fine through holes and / or non-through holes, thereby imparting easy tearing and bending retention.

  The packaging film of the present invention comprises (a) the dead-holding polyester film, or (b) the dead-holding polyester film and a paper sheet and / or other resin film. The packaging film made of the dead-holding polyester film alone is suitable for twist packaging.

  The packaging film in which the dead-holding polyester film and the paper sheet are laminated is suitable for folding packaging applications. A packaging film having at least a paper sheet, the above-described dead-holding polyester film, another paper sheet, a rigid plastic film, and a sealant layer is suitable as a lid for an instant noodle container. A packaging film having at least a paper sheet, the above-described dead-holding polyester film, and a sealant layer is suitable as a lid for a confectionery container.

  The dead-holding polyester film of the present invention consists of a resin composition containing polybutylene terephthalate and polyethylene terephthalate in a mass ratio of 35 to 65:65 to 35, and is amorphous by slowly cooling the melted resin composition. Since the film is stretched while being held in a state, it is excellent in dead hold property, particularly in twist holding property, and also in transparency. The dead-holding polyester film of the present invention having such characteristics is suitable for various packaging applications including food use.

[1] Raw Material Polyester Resin Composition The dead-holding polyester (PES) film of the present invention comprises a resin composition containing polybutylene terephthalate (PBT) and polyethylene terephthalate (PET).
(1) Raw material polybutylene terephthalate The polybutylene terephthalate (PBT) used as a raw material is not particularly limited, but is preferably a homopolymer composed of 1,4-butanediol and terephthalic acid. However, a diol component other than 1,4-butanediol or a dicambonic acid component other than terephthalic acid may be included as a copolymerization component. Examples of such a diol component include ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-cyclohexane methanol, and the like. Examples of the dicarboxylic acid component include isophthalic acid, sebacic acid, adipic acid, azelaic acid, and succinic acid. Specific examples of preferable PBT include homo PBT commercially available from Toray Industries, Inc. under the trade name “Trecon”.

  PBT generally has a melting point of about 220-230 ° C and a glass transition temperature (Tg) of about 20-45 ° C. The melting point can be measured by ASTM D4591, and the glass transition temperature can be measured by JIS K7121 (the same applies hereinafter).

  The molecular weight of PBT is preferably relatively high. When the dead-holding PES film is produced by air-cooled inflation molding, the higher the molecular weight, the more the bubble expands when the tube of the molten resin composition extruded from the annular die is expanded by air injection. It is easy to keep the part in an amorphous state. Specifically, the IV value (intrinsic viscosity) of PBT is preferably 0.8 to 1.5.

(2) Raw material polyethylene terephthalate Polyethylene terephthalate (PET) as a raw material is not particularly limited, but is preferably composed of a homopolymer having ethylene glycol and terephthalic acid as constituent components. However, a diol component other than ethylene glycol or a dicambonic acid component other than terephthalic acid may be included as a copolymer component. Examples of such diol components include diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanemethanol, and examples of the dicarboxylic acid component include isophthalic acid, sebacic acid, adipine, and the like. Acid, azelaic acid, succinic acid and the like can be mentioned. PET preferably contains isophthalic acid as a dicarboxylic acid component other than terephthalic acid. When PET contains an isophthalic acid component, the crystallinity of the dead-holding PES film is improved. PET generally has a melting point of about 250-270 ° C and a glass transition temperature of about 70-80 ° C.

(3) Mixing ratio
The blending ratio of PBT and PET is 35 to 65% by mass of PBT, where the total of PBT and PET is 100% by mass. When the PBT content is less than 35% by mass, the dead hold property is lowered. When the content of PBT is more than 65% by mass, the dead hold property and transparency are deteriorated. The content of PBT is preferably 45 to 65% by mass. The melting point of the PES resin composition is about 230 to 250 ° C., and Tg is about 30 to 70 ° C.

(4) Other resins
The PES resin composition is not limited to the case consisting of only PBT and PET, and may contain other resins depending on the purpose as long as the effects of the present invention are not impaired. Other resins include polyesters such as polyethylene naphthalate (PEN); polyphenylene sulfide (PPS); polyamide (PA); polyimide (PI); polyamideimide (PAI); polyethersulfone (PES); PEEK); polycarbonate; polyurethane; fluororesin; polyolefin such as polyethylene and polypropylene; polyvinyl chloride; In particular, when the resin composition contains a polyolefin such as polyethylene and polypropylene and / or an elastomer, the melt viscosity and the melt tension increase, so that the film formability during film production is improved and the resulting film mechanically. It is preferable because strength and heat sealability are improved. Among these, the resin composition preferably contains polyethylene. When other resin is contained, the ratio is preferably 5 to 15% by mass, more preferably 5 to 10% by mass, based on 100% by mass of the entire resin composition.

(5) Additive
Known additives added to general thermoplastic resins and thermosetting resins in PES resin compositions, that is, stabilizers such as plasticizers, antioxidants and ultraviolet absorbers, antistatic agents, surfactants, dyes Colorants such as pigments and pigments, lubricants for improving fluidity, crystallization accelerators (nucleating agents), inorganic fillers and the like can be used as appropriate according to the required performance.

[2] Method for Producing Dead-Holding Polyester Film The dead-holding PES film of the present invention is produced by melting the raw material PES resin composition, stretching it while slowly cooling it and keeping it in an amorphous state. As a method of stretching while maintaining the raw material PES resin composition in an amorphous state, (a) an air-cooled inflation method in which a tube obtained by extruding a molten PES resin composition from an annular die is expanded by air injection, and (b) Extruding the melted PES resin composition from a T-die and forming an amorphous sheet by removing the temperature on a heated casting roll, while maintaining the resulting amorphous sheet in an amorphous state Examples of the casting method include uniaxial stretching or biaxial stretching. Of these, the air-cooled inflation method is preferred. Hereinafter, a method for producing the dead-holding PES film of the present invention by the air cooling inflation method will be described in detail.

  FIG. 1 shows the steps of a method for producing a dead-holding PES film by an air-cooled inflation molding method. The tubular film extruded from the annular die 1 attached to the extruder 12 is rapidly expanded into a film having a predetermined width by sending air into the inside from the air injection pipe 26 and sandwiched between the take-up machine nip rolls 13. Take-up and take-up by take-up reel 14. The annular die 1 has an annular die head 10 and a weld portion 11. There are no particular restrictions on the air injection means for supplying the air to be injected into the tubular film, and examples include means having a structure in which the air injection pipe 26 is connected to a blower, means having a structure in which the air injection pipe 26 is connected to a compressed air cylinder, and the like. Can do.

  In order to manufacture a dead-holding PES film, first, PBT, PET, and desired additives are kneaded. When kneading is performed in an extruder such as a single screw extruder so that the kneading temperature does not become higher than necessary, the one having a screw structure that does not generate heat or one having an appropriate cooling device is used.

  The extrusion resin temperature of the PES resin composition is the melting point of the PES resin composition (hereinafter simply referred to as “melting point” unless otherwise specified) −30 ° C. to melting point + 20 ° C., preferably melting point −20 ° C. to melting point + 10 ° C. To do. The temperature of the extruded resin is measured by a temperature detector 112 (such as a thermocouple) provided in the resin flow path of the weld portion 11 that connects the outlet 110 of the extruder 12 and the inlet 111 of the die head 10. Since the extrusion speed of the resin is very high, it is estimated that the temperature at the outlet 110 of the extruder 12 and the outlet of the die head 10 is substantially within the temperature range of -30 ° C to 20 ° C. However, the structure of the weld portion 11 is not limited to the illustrated one. By setting the extrusion resin temperature to a melting point of −30 ° C. to a melting point of + 20 ° C., a dead-holding PES film having a high degree of crystallinity and excellent film thickness uniformity and heat shrinkage resistance can be obtained.

Extrusion resin pressure is 8.3 to 13.7 MPa (85 to 140 kgf / cm ² ). Since the resin pressure in the die head 10 cannot be measured due to the configuration of the apparatus, the pressure measured by the pressure detector 121 provided at the extruder outlet 110 is set as the extrusion resin pressure. By setting the extrusion resin pressure to 8.3 to 13.7 MPa, a resin having a sufficient melt viscosity can be extruded to form bubbles. The extrusion resin pressure is preferably 9.3 to 11.8 MPa (95 to 120 kgf / cm ² ). The extrusion resin pressure can be adjusted by changing the mesh of the screen pack 120 in the extruder or changing the gap between the annular orifices.

  The outer diameter of the die lip of the die head 10 is preferably 120 to 250 mm, and the die lip gap is preferably 0.8 to 1.2 mm.

  Bubbles 3 extruded from the annular die 1 are stretched not only in the longitudinal direction (MD) but also in the transverse direction (TD) while being gradually cooled by a cooling device. In FIG. 2, the bubble cooling device includes a first hot air blowing device 20 provided in the vicinity of the annular die 1, a second hot air blowing device 21 provided above the first hot air blowing device 20, A third warm air blowing device 22 provided above the second warm air blowing device 21, a partition wall 23 provided above the third warm air blowing device 22, and a heating means 24 provided inside the partition wall 23; And a cylindrical net 25 provided inside the partition wall 23 (on the bubble 3 side). In FIG. 2, 15 indicates a heat insulating material provided above the annular die 1, and 16 indicates a guide roll.

  In the apparatus having the above configuration, the arrangement of each of the hot air blowing devices 20 to 22 and the partition wall 23 is determined by the temperature control of the bubble 3 formed by the air-cooled inflation molding method. Therefore, the shape and temperature distribution of the bubble 3 will be described below. .

  The melted PES resin composition is extruded from the annular orifice 100 of the die 1 to form a bubble 3. The bubble 3 immediately after extrusion has a small diameter due to a low melt tension, and forms a so-called neck portion 31. . In the neck portion 31, the bubble 3 is mainly stretched to MD. Next, the bubble 3 is rapidly expanded to a predetermined bubble diameter. In the inflating portion 32, the bubble 3 is stretched simultaneously in the MD and TD. There is a frost line 34 in the vicinity of the upper part of the expansion part 32, where the PES resin composition is cooled and solidified. The bubble 3 is further gradually cooled by the partition wall 23 and the heating means 24 provided in the bubble region 33 above the frost line 34.

In order to obtain a dead-holding PES film by the air-cooled inflation molding method as in the present invention, the temperature of each part of the bubble 3 is controlled as follows.
(a) Extrusion resin temperature is controlled from melting point -30 ° C to melting point + 20 ° C.
(b) The neck portion 31 is gradually cooled to a melting point of −60 ° C. to a melting point of −45 ° C.
(c) In the expansion part 32, it is gradually cooled to melting point −90 ° C. to melting point −60 ° C.
(d) In the region of the frost line 34, it is gradually cooled to a melting point of −150 ° C. to a melting point of −110 ° C.
(e) In the bubble region 33, the PES resin composition is maintained at a temperature exceeding Tg to Tg + 45 ° C.

  The condition (a) is the same as described above, but the condition (b) is that the neck portion 31 is not cooled slowly to the melting point −60 ° C. to the melting point −45 ° C. Simultaneous biaxial stretching cannot be sufficiently achieved. That is, by slowly cooling the neck portion 31 to a melting point of −60 ° C. to a melting point of −45 ° C., the expanded portion 32 can be gradually cooled / held at a melting point of −90 ° C. to a melting point of −60 ° C. [Condition (c)]. Specifically, it is preferable that the neck portion 31 is gradually cooled to 180 to 195 ° C. If the expanded part 32 is not maintained at a melting point of −90 ° C. to a melting point of −60 ° C., the expanded part 32 does not have an appropriate melt tension, and the MD is mainly stretched and cannot be thinned. If the expansion part 32 is made to have a melting point of less than −90 ° C., crystallization proceeds, so that the amorphous state cannot be maintained. Specifically, it is preferable to slowly cool the expanded portion 32 to 150 to 180 ° C.

  In order to satisfy such a temperature condition, the blow-up ratio (bubble diameter / die diameter) is preferably set to 2.0 to 4.0. In particular, the blow-up ratio is preferably 2.0 to 3.6.

  Regarding condition (d), the bubble temperature in the region of the frost line 34 is gradually cooled to the melting point −150 ° C. to the melting point −110 ° C. to sufficiently achieve simultaneous biaxial stretching of the bubble 3 to the MD and TD. Can do. If the bubble temperature in the region of the frost line 34 is lower than the melting point −150 ° C., film wrinkles may occur. Specifically, the region of the frost line 34 is preferably slowly cooled to 90 to 130 ° C.

  Regarding the condition (e), by maintaining the bubble 3 above the frost line 34 at a temperature exceeding Tg of the PES resin composition to Tg + 45 ° C. or less, the formation of a uniform thin bubble 3 can be prevented. Can be stabilized. Preferably, bubble region 33 is maintained at 90-110 ° C. If the temperature of the bubble region 33 is kept below the Tg of the PES resin composition without providing the partition wall 23 and the heating means 24, non-uniform stretching may occur, so that the bubble 3 as a whole becomes unstable.

  In the present invention, it is preferable to further surround the outer periphery of the bubble region 33 with a cylindrical net 25 as shown in FIG. As a result, the temperature of the bubble region 33 can be further stabilized and the roll of the bubble 3 can be prevented.

In order to control the temperature of the bubble 3 as described above, the first hot air blowing device 20, the second hot air blowing device 21, the third hot air blowing device 22, the partition wall 23, the heating means 24, and the cylindrical net 25 are used. The arrangement of is as follows.
(i) First hot air blowing device 20
Hot air is blown out so that the temperature of the neck part 31 is gradually cooled to the melting point −60 ° C. to the melting point −45 ° C. provided near the annular die 1. The temperature of the warm air is preferably 25 to 50 ° C.
(ii) Second hot air blowing device 21
It is provided directly under the expansion part 32, and warm air is jetted out so that the temperature of the expansion part 32 is gradually cooled to the melting point −90 ° C. to the melting point −60 ° C. The temperature of the warm air is preferably 25 to 50 ° C.
(iii) Third hot air blowing device 22
It is provided directly below the frost line 34, and hot air is blown out so that the temperature of the region of the frost line 34 is gradually cooled to the melting point -150 ° C to the melting point -110 ° C. The temperature of the hot air is preferably more than Tg of the PES resin composition and not more than Tg + 45 ° C.
(iv) Partition wall 23 and heating means 24
The partition wall 23 is located above the third hot air blowing device 22 so as to surround the bubble region 33 and so that the warm air blown from the first to third hot air blowing devices blows up along the outer surface of the bubble region 33. Provide. The heating means 24 is provided inside the partition wall 23. By providing the partition wall 23 and the heating means 24, the bubble region 33 can be shielded from the influence of the external atmosphere (air temperature, temperature, etc.), and can always be maintained above Tg to Tg + 45 ° C. of the PES resin composition.
(v) Cylindrical net 25
It is provided so as to surround the bubble region 33 inside the partition wall 23.

  In the above method, there is no particular limitation on the means for supplying hot air to be blown out from each of the first to third hot air blowing devices, and examples include a blower capable of controlling temperature. The flow rate of the warm air blown from each of the first to third warm air blowing devices is appropriately adjusted so that the bubble temperatures in the regions of the neck portion 31, the expansion portion 32, and the frost line 34 are in the above temperature ranges, respectively. . If the stable slow cooling effect cannot be obtained, the bubble 3 becomes unstable. Therefore, the temperature of the hot air is controlled so as not to change as much as possible.

  The material of the partition wall 23 is not particularly limited, but is preferably an acrylic resin so that the bubble region 33 surrounded by the partition wall 23 can be observed. If the bubble region 33 can be surrounded from four sides, the shape of the partition wall 23 is not particularly limited, and examples thereof include a cylindrical structure and a rectangular parallelepiped structure, and a cylindrical structure is preferable. As the heating means 24 provided inside the partition wall 23, for example, a rod-shaped or ribbon-shaped electric heater can be used. It is preferable to provide a plurality of rod-shaped electric heaters. An aluminum foil may be attached to the inner surface of the partition wall 23 to block heat radiation. If necessary, a means for blowing cold air of about room temperature may be provided below the partition wall 23 (immediately above the third hot air blowing device 22). This facilitates not only the temperature adjustment inside the partition wall 23 but also the air flow adjustment inside the partition wall 23.

  As shown in FIG. 2, it is preferable to provide a hot air outlet 230 at the upper part of the partition wall 23. By providing the warm air outlet 230, the warm air ejected from the first to third warm air blowing devices can be rectified. For this reason, it is possible to prevent the bubbles 3 from rolling due to warm air. Two or more hot air outlets 230 are preferably provided, and more preferably 2 to 4 hot air outlets 230 are provided. In the example shown in FIG. 2, the hot air discharge port 230 is provided on the upper portion of the side surface 231 of the partition wall 23, but may be provided on the upper surface 232 of the partition wall 23. However, the number and the diameter of the hot air outlets 230 are set such that the heat retention by the partition wall 23 is not impaired.

  As shown in FIG. 2, a ring-shaped rectifying plate 28 is preferably provided on the inner upper portion of the partition wall 23. By providing the current plate 28, the ability to rectify the warm air blown from the first to third warm air blowing devices is improved, and the roll 3 is prevented from rolling. As shown in FIG. 2, the rectifying plate 28 preferably extends from the vicinity of the cylindrical net 25 to the vicinity of the inner surface of the partition wall 23. There are no restrictions on the structure of the current plate 28, and the structure is partitioned by plates arranged in one direction as shown in FIG. 2 and FIG. 3 (a), and is divided into a grid as shown in FIG. 3 (b). Examples of such a structure include a punching plate having a large number of round holes as shown in FIG. The aperture ratio of the current plate 28 is preferably 40 to 60%. There are no particular limitations on the material constituting the current plate 28, and examples thereof include aluminum and synthetic resin. There is no particular limitation on the number of the rectifying plates 28 to be installed, but usually one sheet may be provided.

  As the fibers constituting the cylindrical net 25, natural fibers such as silk and cotton, plastic fibers such as nylon, polypropylene and polyester, metal fibers such as stainless steel, copper, brass and nickel can be used. When a net-like net is used as the cylindrical net 25, the net is preferably 5 to 20 mesh, more preferably 8 to 10 mesh.

  Film formation by the air-cooled inflation molding method of the PES resin composition in the present invention is possible by maintaining the above requirements, and general conditions of the inflation method can be applied to other conditions. That is, using a crosshead die, the tube-shaped PES resin composition is extruded upward or downward, the ends are sandwiched between pinch rolls, air is sent into it and continuously wound up while being inflated to a predetermined size. Uneven thickness can be prevented by rotating or reversing.

  According to the manufacturing method of the present invention, each part of the bubble (immediately after extrusion, the neck part, the expansion part, the frost line area, and the bubble area) is always maintained at a desired temperature, so that the quality is always uniform. Furthermore, high-speed film formation is possible.

  The dead-holding PES film (inflation PES film) obtained by the air-cooled inflation molding described above is uniaxially cold-drawn in the MD or TD direction, or biaxially cold-drawn in the MD and TD directions as necessary. May be. As a result, the inflation PES film can be further thinned, and the film thickness uniformity and transparency are improved. The temperature of cold drawing is preferably in the range of more than Tg of the PES resin composition to Tg + 40 ° C. or less. Specifically, the cold stretching temperature is more preferably in the range of 75 to 85 ° C. The stretching ratio of the uniaxial cold stretching is preferably 2 times or more in the MD direction or TD direction, and more preferably 2 to 6 times. When uniaxial cold drawing is performed, it is preferably performed in the MD direction. The stretching ratio of such biaxial cold stretching is preferably 4 times or more in terms of surface magnification, and more preferably 4 to 16 times. Biaxial cold stretching may be sequential biaxial stretching or simultaneous biaxial stretching, but sequential biaxial stretching is preferred.

  Generally, when a PES film is stretched at a temperature exceeding Tg + 40 ° C., crystals are oriented in the stretching direction, so that the tensile strength, elastic modulus, rigidity, etc. in the orientation direction are greatly improved. However, since the strength in the non-oriented direction is lowered, there is a problem that the film is torn when sequentially biaxially stretched at a temperature exceeding Tg + 40 ° C. On the other hand, when the PES film is cold-drawn at a temperature exceeding Tg to Tg + 40 ° C. or less, the orientation of the molecular chain in the drawing direction is less than when the PES film is drawn at a temperature exceeding Tg + 40 ° C. For this reason, the film does not tear even if the biaxial stretching is sequentially performed on the inflation PES film at a temperature exceeding Tg to Tg + 40 ° C. Moreover, even if uniaxial stretching is performed by cold stretching at a temperature exceeding Tg to Tg + 40 ° C. or less, easy tearing does not occur. Further, by cold drawing at a temperature of more than Tg to Tg + 40 ° C. or less, the crystals are broken and fine spherulites are generated, so that the transparency of the film is improved. Examples of the apparatus used for uniaxial cold drawing and sequential biaxial cold drawing include those described in WO 2004/026558.

[3] Dead hold property polyester film The PES film 3 obtained by the air-cooled inflation molding is excellent in dead hold property, twist hold property and transparency. Specifically, the recovery angle of the air-cooled inflation molded PES film 3 is 30 degrees or less, the twist holding angle is 450 degrees or more, and the haze value (JIS K7105) is 15% or less. Here, the “recovery angle” means that a 4 cm × 2 cm strip test piece as shown in FIG. 4A is cut out from the PES film 3, and the obtained strip test piece is elongated as shown in FIG. 4B. Bend in the direction, put a 200 g rectangular weight on the bent part and leave it for 5 seconds, remove the weight as shown in Fig. 4 (c), measure the rising angle θ, and calculate the average value of 5 tests It is a thing. A smaller value means a better result. Here, the “twist holding angle” means that a 16 cm × 16 cm square test piece is cut out from the PES film 3 and a 2 cm diameter iron ball is placed in the center of each square test piece. Wrapped in a test piece film, twisted 1.5 times (540 degrees) in opposite directions on both sides of the iron ball, left in an environment of 23 ° C and 50% relative humidity for 24 hours, and then twisted on both sides of the iron ball The angle held in the measured state was measured, and the average value of five tests was calculated.

  The air-cooled inflation molded PES film 3 is also excellent in film thickness uniformity and heat shrinkage resistance. Specifically, the film thickness difference of the film having an average film thickness of 8 to 30 μm is 1 to 3 μm, and the thermal contraction rate is 0.1% or less in the MD direction and 0.15% or less in the TD direction. The thickness difference is a value obtained by measuring a total of 6 points of the thickness at the center and both ends in the width direction of the PES film, and calculating the difference between the maximum value and the minimum value. A smaller value means a better result. The heat shrinkage is a value obtained by measuring the shrinkage of MD and TD when the PES film 3 is exposed at 150 ° C. for 10 minutes. ]. For this reason, a printed layer and a metal vapor deposition layer with little unevenness can be formed. In addition, there is little change in film dimensions in secondary processing such as heat sealing and printing.

  The PES film 3 manufactured by the air-cooled inflation molding method is excellent in dead hold property, particularly twist hold property as described above. The region from the neck of the bubble to the frost line is gradually cooled to form an amorphous state. Since the bubble region is maintained at a temperature exceeding Tg of the PES resin composition to Tg + 45 ° C. or less, while being stretched almost uniformly in the MD direction and the TD direction, there is no distortion (stress) in the generated bubbles. Conceivable.

  The thickness of the dead-holding PES film 3 may be appropriately set according to the use, but is usually 5 to 40 μm. If this thickness is 5 μm or more, it has sufficient dead-holding property, twist-holding property, aroma retention property and gas barrier property, and also has good glossiness and printing characteristics. On the other hand, even if it exceeds 40 μm, the cost of the film will only rise, and it is meaningless. The preferred thickness of the dead-holding PES film 3 is 10 to 30 μm.

[4] Processing to dead-hold polyester film
(1) Formation of linear traces In order to improve the tearability of the dead-holding PES film, a number of substantially parallel linear traces may be formed by the method described below. In order to achieve both film strength and good linear tearability, the depth of the linear marks is preferably 1 to 40% of the thickness of the dead-holding PES film, specifically 0.1 to 10 μm. Preferably there is. The width of the line marks is preferably 0.1 to 10 μm, and the interval between the line marks is preferably 10 to 200 μm.

  In order to form a linear mark on a dead-holding PES film, for example, a method disclosed in WO 03/091003 can be employed. In this method, a large number of substantially parallel linear marks are formed on a film by sliding the film continuously running against a roll or plate having a number of fine particles having a Mohs hardness of 5 or more on the surface. As the fine particles, diamond fine particles are preferable. As a means for pressing the film against the roll or plate, a means for blowing air or a brush slidably contacting the film is preferable. Since the linear trace obtained by this method does not penetrate the film, it is possible to ensure sufficient aroma retention and gas barrier properties for the dead-holding PES film in which the linear trace is formed.

  It is preferable that the linear trace is formed entirely on at least one surface of the dead-holding PES film. As a result, the dead-holding PES film is given a linear tearability in one direction and can be linearly split along a linear mark from any part.

(2) Formation of micropores In order to improve the easy tearability and bending retention of the dead-holding PES film, a number of micropores may be formed on the entire surface by the method described below. The micropores preferably have an average opening diameter of 0.5 to 100 μm and a distribution density of about 500 holes / cm ² or more. If the distribution density of the micropores is less than about 500 holes / cm ² , the tearability is insufficient. From the viewpoint of film strength, the distribution density of micropores is more preferably 1 × 10 ³ to 1 × 10 ⁴ holes / cm ² , particularly 1 × 10 ^{3 to} 5 × 10 ³ holes / cm ^2. preferable.

  In order to form micropores in the dead-holding PES film, for example, methods disclosed in Japanese Patent No. 2063411 and JP-A-2002-59487 can be employed. For example, in the method of Japanese Patent No. 2063411, a first roll (same as the above-mentioned linear trace forming roll) in which a large number of fine particles having a Mohs hardness of 5 or more having sharp corners adhere to the surface is smooth. Since the film passes while receiving a uniform pressing force with the second roll, many fine holes are formed in the film. As the second roll, an iron-based roll, a stainless-based roll, a special steel roll or the like subjected to Ni plating, Cr plating, or the like can be used. The fine holes may be selectively formed as either through holes or non-through holes depending on the use of the dead-holding PES film. By adjusting the pressing force between the first roll and the second roll, one or both of the through hole and the non-through hole can be formed.

(3) Deposition of ceramic or metal For the purpose of improving the gas barrier property of the dead-holding PES film, metal, ceramic or the like may be deposited. Specific examples of the ceramic to be deposited include silica and alumina. Vapor deposition of metal, ceramic, etc. can be performed by a known method.

(4) Resin coating A resin may be coated for the purpose of improving the gas barrier property and transparency of the dead-holding PES film. Examples of the transparent resin include polyvinyl alcohol polymers.

[5] Packaging Film Since the dead-holding PES film of the present invention is excellent in twist retention and transparency as described above, it is suitable as a packaging film. The packaging film comprises (a) a dead-holding PES film of the present invention, or (b) a laminate comprising the dead-holding PES film of the present invention and a paper sheet and / or another resin film (dead-holding PES). Film laminate). Depending on the application of the packaging film, either a single dead-holding PES film or a dead-holding PES film laminate may be selected. For example, a packaging film composed only of a dead-holding PES film is suitable for twist packaging of relatively large foods such as vegetables and fruits as well as relatively small foods such as candy and strawberries.

(1) Layer configuration example of laminate The layer configuration example of the dead-holding PES film laminate will be described below. In the example shown in FIG. 5, a printing layer 301, a paper sheet 302, an adhesive layer 303, and a dead-holding PES film 3 are sequentially laminated. Since this dead-holding PES film laminate 30 is excellent in bending retention, it is suitable for folding packaging applications. For example, it is suitable as an alternative material for laminates made of aluminum foil and paper sheets conventionally used for packaging chocolate, butter, tobacco and the like.

  In the example shown in FIG. 6, the printed layer 301, the paper sheet 302, the polyethylene layer 304, the dead-holding PES film 3, the adhesive layer 305, the paper sheet 302, the adhesive layer 306, the rigid plastic film 307, the adhesive layer 308 and A sealant layer 309 is sequentially laminated. The dead-holding PES film laminate 30 is suitable for use as a lid material for instant noodle containers that contain cup ramen, cup fried noodles, and the like. The lid made of this dead-holding PES film laminate 30 is excellent in opening retention.

  In the example shown in FIG. 7, a printing layer 301, a paper sheet 302, a polyethylene layer 304, a dead-holding PES film 3, an adhesive layer 310, and a sealant layer 309 are sequentially laminated. This dead-holding PES film laminate 30 is suitable for use as a cover material for paper containers that contain, for example, confectionery. The lid made of this dead-holding PES film laminate 30 is also excellent in opening retention.

Hereinafter, each layer will be described in detail.
(i) Print layer The print layer 301 can be provided by gravure printing, inkjet printing, or the like. As printing ink, what mixed the pigment and various additives with base thermoplastic resins, such as an acrylic resin type, a polyester resin type, and a polyurethane resin type, can be used. Two-component polyurethane resin-based printing inks are excellent in water resistance.

(ii) Paper sheet The paper sheet 302 also functions as a dead hold property imparting layer. The type of paper is not limited and includes synthetic paper. The basis weight of the paper sheet 302 is preferably about 20 to 120 g / m ² and more preferably about 30 to 80 g / m ² . If the basis weight of the paper sheet 302 is less than about 20 g / m ² , the paper sheet 302 is too weak to provide sufficient dead hold property. On the other hand, even if the basis weight of the paper sheet 302 exceeds about 120 g / m ² , only the cost increases and no further improvement in dead hold property is recognized.

(iii) Rigid plastic film The rigid plastic film 307 is preferably made of a PET film. In order to improve the linear tearability of the PES film laminate 30, it is preferable to use a biaxially oriented PET film having a uniaxial orientation or a different degree of orientation as the PET film. Biaxially oriented PET films with different degrees of orientation are commercially available as “Emblet PC” (Unitika Ltd.). Further, when a large number of substantially parallel linear marks and / or a large number of fine holes as described above are formed in the rigid plastic film 307, the linear tearability of the PES film laminate 30 is improved.

(iv) Sealant layer The sealant film 309 can be formed of a polyethylene film, an unstretched polypropylene film, an ionomer resin film, a polystyrene film, or the like. The sealant film 309 preferably has an easy peel property so that the lid made of the PES film laminate 30 can be easily peeled from the container body. Therefore, it is preferable that the sealant film 309 has a relatively weak thermal adhesiveness. A known hot melt can also be used as the sealant layer 309.

  As the sealant film 309, for example, a laminated film having a polyethylene base film and a low molecular weight polyethylene film in this order from the paper sheet 302 side can be used. The thickness of the polyethylene base film is preferably about 10 to 40 μm, more preferably about 20 to 30 μm. The thickness of the low molecular weight polyethylene film is preferably about 5 to 20 μm, more preferably about 7 to 15 μm. Such a laminated polyethylene film is commercially available, for example, as 760FD (manufactured by Toray Synthetic Film Co., Ltd.). As the sealant film 211, a film made of a mixture of ethylene-vinyl acetate copolymer (EVA) and polyethylene can also be used. In the film made of this mixture, linear low density polyethylene (LLDPE) is preferable as the polyethylene. The thickness of the film made of this mixture is also preferably about 10 to 40 μm, more preferably about 20 to 30 μm. The thickness of the hot melt layer is preferably 10 to 50 μm, more preferably 20 to 40 μm.

A linear ethylene / α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 18 carbon atoms as the sealant film 309 [density (JIS K6922): 0.870 to 0.910 g / cm ³ , MFR (JIS K6921, 190 ° C., 2.16 kg load): 1 to 100 g / 10 min] and a sealant film (Japanese Patent Laid-Open No. 2004-26190) made of a resin composition containing polystyrene. When a lid having a heat seal layer made of this sealant film is heat sealed to the container body, both sealing performance and easy opening performance can be achieved.

  In order to give the PES film laminate 30 excellent linear tearability, the sealant film 309 may be formed with a number of substantially parallel linear marks and / or a number of micropores as described above.

(v) Adhesive layer Although there is no restriction | limiting in particular in an adhesive layer, It is preferable to consist of film-form plastics which have adhesiveness. When the PES film laminate 30 is used as a food packaging film, it is preferable to use a low-odor acrylic water-soluble resin (for example, trade name “Life Bond RA-1A”, manufactured by Nippon Steel Chemical Co., Ltd.). When the PES film laminate 30 is formed by an extrusion lamination method, it is preferable to use polyethylene as the adhesive layer.

(vi) Other layers In order to prevent the packaged contents from being deteriorated by sunlight or ultraviolet rays, the PES film laminate 30 may have a light-shielding ink layer. The light-shielding ink layer is preferably provided on the PES film 3. The light-shielding ink is not particularly limited as long as it is an ink containing a black or dark pigment or dye such as carbon black. The light-shielding ink layer has an advantage that there is no adverse influence on the environment during the incineration process, and also has an advantage that the metal foreign matter in the sealed container can be detected by a metal detector. Therefore, not only the safety of instant foods and the like is further increased, but also the inspection cost can be significantly reduced by using a metal detector.

(2) Method for Producing Dead Hold Polyester Film Laminate When producing the dead hold PES film laminate 30 shown in FIG. 5, the paper sheet 302 provided with the printing layer 301 in advance and the PES film 3 are prepared by the dry lamination method. What is necessary is just to adhere.

When the dead-holding PES film laminate 30 shown in FIG. 6 is manufactured, first, a laminate comprising the printing layer 301, the paper sheet 302, the polyethylene layer 304, and the PES film 3 shown in FIG. 8 (a) [laminate (a). ] Is produced. FIG. 9 shows an example of an apparatus for producing the laminate (a). The PES film 3 rewound from the reel 40 on which the PES film is wound is printed by being rewound from the reel 44 via the pressure adjusting rolls 41 and 41 and the guide roll 42 and through the molten polyethylene 304 extruded from the die 43. through between the pair of cooling rolls 45, 45 'while overlapping requires paper sheet 302 (extrusion lamination), and shaping at a temperature T ₁ of the less than Tg ultra-melting point of the PES while conveying a cooling roll 45 for vehicles . Thereby, the curl shape can be stored in the PES film 3 of the laminate (a). In this specification, curl-shaped memory means that the PES film laminate 30 is exposed to a temperature T ₁ or higher after the shaping treatment, unlike the dead hold property that can maintain the state when the PES film laminate 30 is warped. By the above, it means the property of returning from the shape (flat shape, reverse curl shape, etc.) given after the shaping process to the curl shape (the PES film laminate 30 can be warped). For example, by setting the melting temperature of polyethylene 304 to about 300 ° C., the PES film 3 can be shaped at about 130 ° C.

  When forming the laminate (a), it is preferable that the PES film 3 is bonded to the paper sheet 302 in the state in which the PES film 3 has been stretched in the MD direction within the elastic deformation region (1 to 3% elongation). Thereby, the curling property can be imparted to the PES film laminate 30. To stretch 1 to 3%, the PES film 3 may be applied with a tension of 10 to 20 kgf / m width. When the PES film 3 is bonded to the paper sheet 302 without being stretched, the tension applied to the PES film 3 is 5 kgf / m width or less.

The laminate (a) obtained by the above-mentioned shaping treatment at the temperature T ₁ , in particular, the one that is bonded to the paper sheet 302 while applying tension to the PES film 3 has a curling property that warps the PES film 3. As shown in FIG. 9, while being wound around the reel 46 with the PES film 3 facing outward, it is cooled to a temperature T _{2 that is} equal to or lower than the Tg of PES. As a result, the laminate (a) does not substantially curl when unwound (of course, the laminate (a) curls over time).

  Next, another paper sheet 302 is adhered to the PES film 3 side of the laminate (a) produced as described above by the dry lamination method, thereby obtaining the laminate (laminate (b )). When a laminated body made of a rigid plastic film 307 and a sealant film 309 formed in advance is bonded to the paper sheet 302 side of the obtained laminated body (b) by a dry lamination method, a dead-holding PES film shown in FIG. 30 is obtained.

When adhering the paper sheet 302 to the laminate (a) and adhering the laminate comprising the rigid plastic film 307 and the sealant film 309 to the laminate (b), the laminate (a) and the laminate (b) was dry laminated with Tg super through T ₁ lower than a temperature T ₃ of the PES while maintaining a flat state, is cooled to a temperature T ₄ of the following Tg of PES. As a result, the dead-holding PES film laminate 30 finally obtained has a flat shape. Dry lamination temperature T ₃ is, for example, about 90 ° C.. By forming the flat-shaped dead-holding PES film laminate 30, there is no hindrance to the work of punching / sealing into the lid. Lid was heat-sealed is processed by T ₁ or more temperature during normal heat sealing, so recover substantially curled shape by shape recovery ability, when peeled from the container body, the curled condition.

  The production method of the dead-holding PES film shown in FIG. 7 is the same as the above except that the sealant film 309 is adhered to the laminate (a).

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
A PES film was produced by an air-cooled inflation molding method using the apparatus shown in FIG. 60 parts by mass of PBT pellets (trade name “Toraycon 1200S”, manufactured by Toray Industries, Inc., melting point: 220 ° C., intrinsic viscosity: 1.2), and 40 parts by mass of PET pellets (including isophthalic acid as a copolymerization component. Melting point: 260 ° C.) (Dry blend), and the resulting mixture is put into a single screw extruder (screw diameter: 50 mm, extrusion rate: 50 kg / hr), melt-kneaded at 240 ° C, and in the extruder A molten resin composition was prepared. Subsequently, the molten resin composition is extruded from the extruder outlet at an extrusion resin temperature of 240 ° C. and an extrusion resin pressure of 11.8 MPa (120 kgf / cm ² ). Further, a die head (die diameter: 150 mm, die lip gap: 0.9 mm) ) Extruded a tube of molten resin composition. The expanded molten resin composition tube is expanded at a blow-up ratio of 3.6, and (1) the bubble neck is gradually lowered to 185 ° C by blowing hot air (30 ° C) from the first hot air blowing device. (2) Slowly cool the bubble expansion to 160 ° C by blowing warm air (30 ° C) from the second hot air blowing device, and (3) Warm air (50) from the third hot air blowing device. The frost line region was gradually cooled to 125 ° C. by ejecting (° C.), and (4) while maintaining the bubble region at 100 ° C., it was drawn at 20 m / min to produce a dead-holding PES film. The cylindrical net surrounding the bubble region is made of nylon, and the acrylic resin cylindrical partition wall is provided with two hot air outlets on the upper side, and a bar heater on the inside. A rectifying plate having a hole area ratio of 60% was provided on the inside.

Example 2
A dead-holding PES film was produced in the same manner as in Example 1 except that the blending ratio of PBT and PET was changed to PBT / PET = 50/50 (mass ratio).

Example 3
A dead-holding PES film was produced in the same manner as in Example 1 except that the blending ratio of PBT and PET was changed to PBT / PET = 40/60 (mass ratio).

Comparative Example 1
A PES film was produced in the same manner as in Example 1 except that the blending ratio of PBT and PET was changed to PBT / PET = 70/30 (mass ratio).

Comparative Example 2
A PES film was produced in the same manner as in Example 1 except that the blending ratio of PBT and PET was changed to PBT / PET = 80/20 (mass ratio).

Comparative Example 3
A PES film was produced in the same manner as in Example 1 except that the blending ratio of PBT and PET was changed to PBT / PET = 30/70 (mass ratio).

<Evaluation of dead hold property>
From the PES films obtained in Examples 1 to 3 and Comparative Examples 1 to 3, 4 cm × 2 cm strip-shaped test pieces as shown in FIG. Two types of strip-shaped test pieces were cut out from each PES film, one whose longitudinal direction was the MD direction of the film and one whose TD direction was the film. Each strip-shaped test piece obtained was bent in the longitudinal direction as shown in FIG. 4 (b), and a 200 g rectangular parallelepiped weight was placed on the bent portion and left for 5 seconds, as shown in FIG. 4 (c). The weight was removed, the rising angle θ was measured, the average value of five tests was calculated, and this was taken as the recovery angle. The results are shown in Table 1 and FIG.

<Evaluation of twist retention>
From the PES films obtained in Examples 1 to 3 and Comparative Examples 1 to 3, square test pieces of 16 cm × 16 cm square were cut out. Place a 2cm diameter iron ball in the center of each square test piece obtained, wrap it in a square test piece film, twist it 1.5 times (540 degrees) in opposite directions on both sides of the iron ball, After being allowed to stand for 24 hours in an environment of temperature and 50% relative humidity, the angle (twist holding angle) held while twisted on both sides of the iron ball was measured. Calculate the average value of 5 tests, and the following criteria:
◯: Twist holding angle is 450 degrees or more.
Δ: Twist holding angle is 300 degrees or more and less than 450 degrees.
X: Twist holding angle is less than 300 degrees.
It was evaluated by. The results are shown in Table 1.

<Evaluation of transparency>
About the PES film obtained in Examples 1-3 and Comparative Examples 1-3, the haze value was measured by JISK7105. The results are shown in Table 1.

Comparative Example 4
A commercially available biaxially stretched polypropylene (OPP) film [trade name “Pyrene” (manufactured by Toyobo Co., Ltd.), thickness: 20 μm] was evaluated in the same manner as described above for dead hold property and twist hold property. The results are shown in Table 1.

Comparative Example 5
With respect to commercially available moisture-proof cellophane [trade name “MST” (manufactured by Sekisui Chemical Co., Ltd.), thickness: 20 μm] (Comparative Example 5), dead hold property and twist hold property were evaluated in the same manner as described above. The results are shown in Table 1.

Comparative Example 6
The dead hold property and the twist retention property were evaluated in the same manner as described above for a commercially available biaxially stretched PET film [trade name: “Ester film” (manufactured by Toyobo Co., Ltd.), thickness: 12 μm] (Comparative Example 6). . The results are shown in Table 1.

表１（続き）

Table 1 (continued)

Note: (1) Toray Industries, Inc. trade name “Torekon”.
(2) Contains isophthalic acid as a copolymerization component.
(3) Using a contact thickness meter, the values obtained by measuring the film thicknesses at a total of six points, each of two points at the center and both ends in the width direction of the sheet, were averaged.
(4) The longitudinal direction of the strip specimen is the MD direction of the film.
(5) The longitudinal direction of the strip specimen is the TD direction of the film.

  As is clear from Table 1 and FIG. 10, the PES films of Examples 1 to 3 are excellent in any of dead hold property, twist hold property and transparency. On the other hand, in Comparative Examples 1 to 3, since the blending ratio of PBT and PET is outside the range of the present invention, the dead hold property and the twist retention property are inferior. In Comparative Examples 1 and 2, the transparency is also inferior. It was. In Comparative Examples 4 to 6, which are conventional packaging films, both the dead hold property and the twist hold property were inferior.

It is the schematic which shows an example of the apparatus which manufactures the dead hold property polyester film of this invention by the air cooling inflation molding method. It is a schematic sectional drawing which shows an example of the apparatus which cools a bubble slowly. 3A is a plan view showing an example of the current plate, FIG. 3B is a plan view showing another example of the current plate, and FIG. 3C is still another example of the current plate. FIG. 4 (a) is a perspective view showing a test piece for evaluating the dead hold property, and FIG. 4 (b) is a perspective view showing a state in which the test piece of FIG. 4 (a) is bent and a weight is placed on the bent portion. FIG. 4 (c) is a perspective view showing a bent state of the test piece after the weight of FIG. 4 (b) is removed. It is sectional drawing which shows the layer structural example of the film for packaging of this invention. It is sectional drawing which shows another layer structural example of the film for packaging of this invention. It is sectional drawing which shows another example of a layer structure of the film for packaging of this invention. 8A is a cross-sectional view showing a state in which a paper sheet and a PES film are bonded, and FIG. 8B is a cross-sectional view showing a state in which the paper sheet is bonded to the laminate of FIG. 8A. FIG. 8 (c) is a cross-sectional view showing a state in which a rigid plastic film and a sealant film are laminated on the laminate of FIG. 8 (b). It is the schematic which shows an example of the apparatus which forms the laminated body of Fig.8 (a). It is a graph which shows the relationship between PBT content and a recovery angle about the polyester film of Example 1 and Comparative Examples 1 and 2.

Explanation of symbols

1 ... Inflation die
10 ... Die head
100 ・ ・ ・ Ring orifice
11 ... Weld part
110 ・ ・ ・ Extruder outlet
111 ・ ・ ・ Die head entrance
112 ・ ・ ・ Temperature detector
12 ... Extruder
120 ... Screen pack
121 ... Pressure detector
13 ... Tipper nip roll
14 ... take-up reel
15 ... Insulation
16 ... Guide roll
17 ... Nip roll
20 ... First hot air blowing device
21 ... Second hot air blowing device
22 ・ ・ ・ Third hot air blowing device
23 ... Bulkhead
230 ・ ・ ・ Hot air outlet
231 ・ ・ ・ Side wall side
232 ・ ・ ・ Bump top surface
24 ・ ・ ・ Heating means
25 ... Cylindrical net
26 ... Air injection pipe
28 ... Rectifying plate 3 ... Bubble, dead hold PES film
30 ・ ・ ・ Dead-holding PES film laminate
31 ... Neck
32 ... Expanded part
33 ・ ・ ・ Bubble area
34 ... Frost line
301 ... Printed layer
302 ・ ・ ・ Paper sheet
303,305,306,308 ... Adhesive layer
304 ・ ・ ・ Polyethylene layer
307 ・ ・ ・ Rigid plastic film
309 ・ ・ ・ Sealant film
40, 44, 46 ... reel
41 ... Pressure adjustment roll
42 ... Guide roll
43 ... Die
45, 45 '・ ・ ・ Cooling roll

Claims (10)

A film comprising a resin composition containing polybutylene terephthalate and polyethylene terephthalate, having a dead hold property, wherein the resin composition comprises 100% by mass of polybutylene terephthalate and polyethylene terephthalate as a total of 35 to 65 masses of polybutylene terephthalate. A dead-holding polyester film, wherein the resin composition is contained while being melted and is slowly cooled and stretched while being kept in an amorphous state. The dead-holding polyester film according to claim 1, wherein the dead-holding polyester film is formed by an air-cooled inflation method in which a tube obtained by extruding the molten resin composition from an annular die is expanded by injecting air. Hold polyester film. The dead-holding polyester film according to claim 1 or 2, wherein a haze value is 15% or less. The dead-holding polyester film according to any one of claims 1 to 3, wherein a number of fine through-holes and / or non-through-holes are uniformly formed, and thus have easy tearability and bend retention. Characteristic dead hold polyester film. A packaging film comprising the dead-holding polyester film according to claim 1. 6. The packaging film according to claim 5, wherein the packaging film is for twist packaging. A packaging film comprising a laminate comprising the dead-holding polyester film according to claim 1 and a paper sheet and / or another resin film. 8. The packaging film according to claim 7, wherein the dead-holding polyester film and a paper sheet are laminated, and the packaging film is for folding packaging. The packaging film according to claim 7, which has at least a paper sheet, the dead-holding polyester film, another paper sheet, a rigid plastic film, and a sealant layer, and is used for a lid for an instant noodle container. Characteristic packaging film. The packaging film according to claim 7, wherein the packaging film has at least a paper sheet, the dead-holding polyester film, and a sealant layer, and is used for a lid for a confectionery container.

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