JP2003170498A - Heat-shrinkable polyester film roll and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyester film roll which can improve the productivity of a shrink-packaged object. <P>SOLUTION: The heat-shrinkable polyester film roll, in a steady area in which the physical properties of the film is stabilized in the longitudinal direction of the film, when a specimen piece is set for every about 100 m, meets the conditions (1) and (2). In the condition (1), each specimen cut off from each specimen piece, when immersed in hot water of 95°C for 10 sec, indicates a heat-shrinkage rate in the maximum shrinkage direction of at least 20%, and a heat-shrinkage rate in the direction perpendicular to the maximum shrinkage direction of 7% or below. In the condition (2), each specimen, when the average heat-shrinkage rate in the orthogonal direction is calculated, indicates a heat- shrinkage rate in the orthogonal direction falling within a range of the average heat-shrinkage rate ±1.5%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a film roll obtained by winding a heat-shrinkable polyester film,
More specifically, a heat-shrinkable polyester film with extremely little occurrence of defects such as insufficient shrinkage, shrinkage spots, wrinkles, distortion, and vertical shrinkage in the post-processing step caused by fluctuations in the heat shrinkage rate in the heat-shrinkable film roll. It's about rolls.

[0002]

2. Description of the Related Art Heretofore, heat-shrinkable films have been widely used for applications such as shrink wrapping and shrink labels by utilizing the property of shrinking by heating. Among them, stretched films made of vinyl chloride resin, polystyrene resin, polyester resin, etc. are polyethylene terephthalate (PET).
In various containers such as containers, polyethylene containers, and glass containers, they are used for the purpose of labels, cap seals, or integrated packaging (see, for example, Patent Document 1).

[0003] These heat-shrinkable films are once wound into a roll after being manufactured, and are sent to a printing process of various designs in the form of this film roll, and after printing is finished, if necessary, a final product. The slits are made according to the size of the label etc. used for, and the left and right edges of the film are overlapped and sealed into a tubular body by means of solvent adhesion or the like, and the tubular body is cut, and the label is cut. Processed into a bag, etc. Inside of a shrink tunnel (steam tunnel) that attaches a label or bag-like thing to the container and blows steam to heat shrink, or a shrink tunnel that blows hot air to shrink heat (hot air tunnel) Is passed through a belt conveyer or the like, heat-shrinked, and brought into close contact with the container.

By the way, in this heat shrinking step, if there is a large variation in the heat shrinkage rate of each unit such as the label or bag, the heating conditions in the tunnel are the same, so that the proper heat shrinkage rate is obtained. Labels and bags not shown will be generated, and these will be insufficient shrinkage, shrinkage spots, wrinkles, pattern distortion,
Since it causes a defective appearance due to vertical sinking or the like, it cannot be a final product. Here, the vertical mark is a defective appearance in which the label has a non-uniform length after contraction, and thus a line in which the upper edge of the label bends downward or a line in which the lower edge bends upward is drawn. .

Usually, the same label / bag for the final product is processed from one film roll, and thus when the variation amount of the heat shrinkage rate of the film wound on one film roll is large, There has been a problem that the defective rate increases in various heat shrinking steps. These defects have been a common problem with heat-shrinkable film rolls that occur even when using a heat-shrinkable film roll made of any of the above-mentioned vinyl chloride resin, polystyrene resin, polyester resin and the like.

[0006]

[Patent Document 1] Japanese Patent Application Laid-Open No. 7-138388 (paragraph 0)
(001-0005)

[0007]

DISCLOSURE OF THE INVENTION The present invention is directed to a defect in the heat shrinking step due to the fluctuation of the heat shrinkage ratio in the film roll as described above, particularly the heat shrinkage at a high temperature of about 90 to 95 ° C. To provide a heat-shrinkable polyester film roll capable of reducing the variation of vertical shrinkage when shrink-wrapping an article to be packaged, and capable of improving the productivity of the shrink-wrapped article to be wrapped, and a method for producing the same. It is what

[0008]

The heat-shrinkable polyester film roll of the present invention is a film roll obtained by winding a heat-shrinkable polyester film, and the heat-shrinkable polyester film has a long film length. When the end on the winding end side of the film is the first end and the end on the winding start side is the second end in the steady region in which the physical properties of the film are stable in the vertical direction, 2 m inside the second end A first sample cutout portion is provided within, and a final cutout portion is provided within 2 m inside the first end portion,
The point is that when the sample cutouts are provided about every 100 m from the first sample cutout, the following requirements (1) and (2) are satisfied.

(1) A 10 cm × 10 cm square sample cut out from each of the cutouts was dipped in warm water of 95 ° C. for 10 seconds and pulled up, and then 2
The heat shrinkage rate in the maximum shrinkage direction when immersed in water at 5 ° C for 10 seconds and pulled up is 20% or more, and the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction is 7% or less (2). 10 cm cut out from each sample cutout part
When the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction was measured by the method described in (1) above for each square sample of × 10 cm, and the average heat shrinkage rate of these orthogonal direction heat shrinkage rates was calculated. The orthogonal heat shrinkage of all samples is
The heat-shrinkable film roll having the above-mentioned characteristics, which is within the range of ± 1.5% of the average heat-shrinkage ratio, has excellent shrink finish over the entire length of the constant region of the film, and in the heat-shrinking step, Since there is little fluctuation in the thermal shrinkage rate of the individual labels, bags, etc. in the direction orthogonal to the maximum shrinkage direction, shrinkage unevenness in this direction can be reduced. Especially 90 ~
Even when heat-shrinking at about 95 ° C., it is possible to reduce variations in vertical sinking.

Further, when the average heat shrinkage of the heat shrinkage in the maximum shrinkage direction measured by the above method is calculated for each of the cut-out samples, the maximum shrinkage heat shrinkage in all the samples is ± 5 of average heat shrinkage in shrinkage direction
If it is within the range of%, more excellent shrink finish can be obtained.

The heat-shrinkable polyester film is preferably formed of a mixture of two or more polymers having different compositions. In such a case, the heat shrinkage property of the film is apt to change, and it is meaningful to apply the present invention. Further, even when the heat-shrinkable polyester-based film has a width of 0.2 m or more and a length of 300 m or more, the heat-shrinkable property of the film is liable to change unless the present invention is applied, which makes sense to apply the present invention. ,
Further, the film having the above width and length is a preferable embodiment of the present invention because it is excellent in processability and handleability in the processing steps from the printing to the final product described above.

The preferred production method for obtaining the heat-shrinkable film roll of the present invention having a small variation in heat-shrinkability is as follows:
A film-forming step of forming a film while mixing a polymer having the largest amount of use and one or more kinds of other polymers having different compositions from each other and performing melt-extrusion, and an unstretched film obtained in this film-forming step are substantially separated from each other. It is composed of a heat-shrinkability imparting step of biaxially stretching at different draw ratios in orthogonal directions, and a rolling step of winding the resulting heat-shrinkable film. An elliptic cylinder having an elliptical cross-section with a major axis and a minor axis is used, and raw material chips of a polymer other than the polymer with the highest usage amount are average long diameters (mm) and average short diameters (mm) of the raw material chips with the highest usage amount. Of the average major axis (mm), the average minor axis (mm), and the average chip length (mm), which are included within ± 20% of the average chip length (mm). Cities, has the gist where to set further stretching temperature "glass transition temperature + 50 ℃ polyester film" or more when stretching ratio smaller direction stretching (sub stretching).

A method of manufacturing a heat-shrinkable film roll, which comprises a step of melt-extruding a film using an extruder equipped with a funnel-shaped hopper as a raw material chip supply section, wherein the inclination angle of the hopper is 65 ° or more. Is also preferable.

Further, the stretching speed of the sub-stretching is 20 to
It is also a preferred embodiment to set in the range of 1,000 times / min and to set the preheating temperature in the preheating step prior to the sub-stretching to a temperature 10 to 80 ° C. lower than the sub-stretching temperature. In addition, the fluctuation range of the surface temperature of the film measured at an arbitrary point in the preheating step, the main stretching step and the heat treatment step prior to the stretching (main stretching) in the direction in which the stretching ratio is large is defined as the average temperature ±
It is also a preferred embodiment to set the temperature within the range of 1 ° C. The stretching speed is defined by the following formula.

Stretching rate = L ₁ / T ₁ [wherein, L ₁ is the stretching ratio, and T ₁ is the time (minutes) required to give the stretching ratio on the left]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of studying variations in vertical sinking, the present inventors have found that this variation is likely to occur mainly when producing a polyester film roll from a polymer blend. That is, it was considered that the composition variation of the blend polymer occurred in the long film, which was one of the factors contributing to the variation of vertical sinking. Then, it has been found that the heat-shrinkable polyester film roll according to the present invention is less likely to cause the above-mentioned problems because the variation in vertical shrinkage is small. Moreover, with the heat-shrinkable polyester film roll according to the present invention, even if heat-shrinked at a high temperature of about 90 to 95 ° C., the fluctuation of vertical sinking can be reduced. Therefore, it has been found that the heat shrinkage temperature can be set to a high temperature and the heat shrinkage time can be shortened, so that the productivity of the labeling step is enhanced. Hereinafter, the present invention will be described in detail.

The object of the present invention is a polyester-based heat-shrinkable film roll. This is because it exhibits good heat shrinkage properties in a wide temperature range from low temperature to high temperature, and an excellent shrink finish appearance with less shrinkage spots, wrinkles and distortion can be obtained. It also has a beautiful gloss and transparency.

The heat-shrinkable polyester film wound around the heat-shrinkable polyester film roll of the present invention has an end on the winding start side of the film in a constant region where the physical properties of the film are stable in the length direction of the film. Part 1
The end portion and the end portion on the winding end side are defined as the second end portion, the first sample cutout portion is located within 2 m of the inside of the second end portion, and the final cutout portion is within 2 m of the inside of the first end portion. With a part, about 10 from the first sample cutout part
When a sample cutout is provided every 0 m, each sample obtained from this steady region must satisfy the following requirements (1) and (2).

(1) For each 10 cm × 10 cm square sample cut out from each of the sample cutouts,
When each sample was dipped in warm water of 95 ° C for 10 seconds and pulled up, and then dipped in water of 25 ° C for 10 seconds and pulled up, the thermal shrinkage in the maximum shrinkage direction was 20% or more for all samples and the maximum shrinkage The heat shrinkage in the direction orthogonal to the direction is 7% or less (2) 10c cut out from each sample cutout part
For each square sample of m × 10 cm, the above (1)
The heat shrinkage in the direction orthogonal to the maximum shrinkage direction is measured by the method described in 1, when the average heat shrinkage of these orthogonal heat shrinkages is calculated, the orthogonal heat shrinkages of all the samples are The range is within ± 1.5% of the average heat shrinkage. First, the meaning of "a steady region in which the physical properties of the film are stable in the length direction of the film" that specifies the sample cutout portion will be described. The "steady region in which the film physical properties are stable in the length direction of the film" is a region in which the film forming process and the stretching process are stably performed during the film production, and the film physical properties are substantially uniform. In the present invention, in the long film obtained when the film forming process and the stretching process are operated in a stable steady state, it is a technique to highly uniformize the heat shrinkage ratio in the direction orthogonal to the maximum shrinkage direction. It is thought. In actual operation, the film physical properties may change during the film production depending on the raw material supply method and the film forming conditions.
In the present invention, the film obtained when the film forming process or stretching process is unstable does not require homogenization. For this reason, it was premised that sampling when evaluating the characteristics requiring uniformization is performed only in a region where the film forming process and the stretching process are operated in a stable steady state, that is, a “steady region”.

Therefore, for example, if about 10 m from the beginning of winding is a film which is not in steady operation, sampling is not performed from this portion, and 10 m from the beginning of winding is sampled as the first end of the film.

The number of the steady-state regions (steady-state operating regions) is usually one in one film roll (one in the whole film roll). However, depending on the manufacturing situation, there may be cases in which there are multiple locations, so in this case, sampling is performed only from the steady region. The steady region can be evaluated by, for example, measuring the maximum heat shrinkage stress value in the maximum shrinkage direction of the film. That is, if the maximum thermal shrinkage stress value is within a range of about 3 MPa (the difference between the maximum value and the minimum value of the maximum thermal shrinkage stress values of a plurality of samples is within about 3 MPa), it can be regarded as a steady region. Good.

Here, the maximum heat shrinkage stress value is measured as follows. (1) Prepare a sample having a maximum contraction direction length of 200 mm and a width of 20 mm. (2) Set the temperature inside the heating furnace of a tensile tester equipped with a hot air heating furnace (for example, "Tensilon" manufactured by Toyo Seiki) to 90 ° C. (3) Heating is stopped, and the sample is set in the heating furnace. The distance between chucks is 100 mm (constant). (4) The door of the heating furnace is quickly closed, and air is blown from the back and left and right outlets of the heating furnace (90 ° C, blowing speed 5 m.
/ S) is restarted to detect and measure the heat shrinkage stress. (5) The maximum value is read from the chart and set as the maximum heat shrinkage stress value (MPa). Next, the sampling method will be described. Regarding the film wound on one roll, when the end on the winding start side of the film in the steady region is the first end and the end on the winding end side is the second end, the first end The first cut-out portion is provided within 2 m from the inside, the final cut-out portion is provided within 2 m from the first end, and the sample cut-out portion is provided about 100 m from the first sample cut-out portion. Thereby, the samples are selected at substantially equal intervals over the entire length of the constant region of the film. In addition,
"Every 100 m" means that the sample may be cut out at about 100 m ± 1 m.

The above sampling method will be described in more detail. For example, when a heat-shrinkable film having a length of 498 m, whose physical properties are stable over the entire length of the film, is wound around a roll, the first sample (10 cm × 10 cm × Cut 10 cm). For the sake of convenience, the square is cut so that it has a side along the longitudinal direction of the film and a side along the direction orthogonal to the longitudinal direction (do not cut diagonally).
I will. Then, the second sample is cut out at a distance of about 100 m from the cut portion. Similarly, a third sample is cut out at about 200 m, a fourth sample is cut out at about 300 m, and a fifth sample is cut out at about 400 m. Here, the rest is shorter than 100m,
The 6th (final) sample is 2m from the beginning of film winding
Cut out any part within.

The requirement (1) of the present invention is that the heat shrinkage in the maximum shrinkage direction of all the samples thus cut is 2
It is 0% or more, and the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction is 7% or less. When the heat shrinkage ratio of the film in the maximum shrinkage direction is less than 20%, the heat shrinkage force of the film is insufficient, and when the film is shrunk by coating on a container or the like,
It is not preferable because it does not adhere to the container and a poor appearance occurs. The heat shrinkage ratio in the maximum shrinkage direction is more preferably 40% or more, and further preferably 60% or more. When the heat shrinkage ratio in the orthogonal direction exceeds 7%, the appearance defect due to the vertical mark is likely to occur even if the variation in the heat shrinkage ratio in the orthogonal direction is suppressed as described later. The heat shrinkage ratio in the orthogonal direction is more preferably 6% or less, still more preferably 5% or less.

Here, the heat shrinkage in the maximum shrinkage direction means the heat shrinkage in the direction in which the sample shrinks most,
The maximum contraction direction and the orthogonal direction are determined by the length of the square in the longitudinal direction or the transverse direction. The heat shrinkage (%) is
A 10 cm × 10 cm sample was immersed in warm water of 95 ° C. ± 0.5 ° C. for 10 seconds under no load to cause heat shrinkage,
It is a value obtained by measuring the lengths in the longitudinal and transverse directions of the film after immersing in water at 25 ° C. ± 0.5 ° C. for 10 seconds under no load and according to the following formula.

Thermal shrinkage = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage) The film manufacturing process does not become extremely unstable even in a portion other than the steady region. As long as it satisfies the range of the maximum shrinkage direction and the thermal shrinkage ratio in the orthogonal direction defined by the requirement (1). In such a circumstance, the heat shrinkage rate in the maximum shrinkage direction and the orthogonal direction in the steady region is set in the requirement (1) because the present invention suppresses the variation in the heat shrinkage rate in the orthogonal direction described later in the steady region. Since the purpose is to improve the usability of the film in the region, it is sufficient if the heat shrinkage ratios in the maximum shrinkage direction and the orthogonal direction are within a predetermined range at least in the region.

In the present invention, in the requirement (2), when the average heat shrinkage of the heat shrinkage in the orthogonal direction is calculated based on all the samples obtained from the cutout portion, the heat in the orthogonal direction of all the samples is calculated. Shrinkage is ± of the average heat shrinkage
Within 1.5% (preferably within ± 1.3%, especially ± 1%
Within)). The meaning of the average heat shrinkage ratio within ± 1.5% will be described in more detail below. That is, the heat shrinkage rate of each of the cut samples is measured, and the average heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction is calculated. When the average value of the heat shrinkage in the orthogonal direction is X (%) and the heat shrinkage in the orthogonal direction of the sample is Y1 (%), | X−Y1 | (absolute value of X−Y1) is 1.5 ( %), And also in the orthogonal direction heat shrinkages Y2 to Y6 (%) of the samples, it is also true that | X−Yn | is smaller than 1.5 (%). ± 1.5% of In other words, the difference between the maximum value Ymax of Yn and X and the minimum value Y
If the difference between min and X is within ± 1.5%, the requirements of the present invention are satisfied. The heat shrinkage measurement temperature is 9
As is clear from the 5 ° C., according to the invention,
Since it is possible to suppress the thermal shrinkage variation in the orthogonal direction at a temperature of 95 ° C., a shrinkable package (label, bag, etc.) is prepared from the film roll, and the packaged object (bottle, etc.) is coated with this. It is possible to prevent the occurrence of vertical sinking even when heat-shrinking at about 90 to 95 ° C. That is, the temperature for heat shrinkage can be increased to about 95 ° C. Therefore, it becomes possible to heat-shrink at a high temperature, and the heat-shrinking time can be shortened, so that the productivity of the coating shrinking step can be improved. The present invention is particularly useful when heat shrinking is performed by using steam as a heat source at a temperature of about 90 to 95 ° C.

In the present invention, it is also a preferable requirement that the variation of the heat shrinkage ratio in the maximum shrinkage direction is small. Specifically, each sample cut out by the sampling method described above,
When the heat shrinkage in the maximum shrinkage direction is measured and the average heat shrinkage of these heat shrinkages is calculated in the same way as the variation in the heat shrinkage in the orthogonal direction is measured (that is, the temperature 9
When calculating the value at 5 ° C.), it is preferable that the thermal shrinkage in the maximum shrinkage direction of all the samples is within ± 5% of the average thermal shrinkage. As a result, defects in the coating shrinkage step are reduced, and the defective rate of the product is further reduced. The fluctuation degree of the heat shrinkage in the maximum shrinkage direction is more preferably within ± 4% of the average heat shrinkage, and even more preferably within ± 3%.

The heat-shrinkable film of the present invention is preferably formed of a mixture of two or more polymers having different compositions. In the case of such a polymer blend, 1
This is because the fluctuation of the heat shrinkage ratio of the film wound on the roll of the book becomes large, and thus it is significant to apply the present invention.

The polyester heat shrinkable film wound around the film roll of the present invention is not particularly limited as long as it is a polyester film and has heat shrinkability. For example, an ethylene terephthalate unit composed of ethylene glycol and terephthalic acid (or dimethyl ester) is used as a basic unit (preferably 5% of all units).
0 mol% or more), as a polyhydric alcohol other than ethylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc., components for ensuring the heat shrinkage ratio, 1,4-butanediol, propylene glycol, etc. Components for exhibiting shrinkage at low temperature (hereinafter, these components for ensuring heat shrinkage, components for exhibiting shrinkage at low temperature may be referred to as shrinkage components), etc. Further included films can be used. By forming a film from the basic unit and the shrinking component and stretching the film at a predetermined ratio or more, which will be described later, it is possible to achieve a heat shrinkage ratio of the predetermined value or more. The shrinking component is not limited to the above 1,4-cyclohexanedimethanol, neopentyl glycol, 1,4-butanediol, propylene glycol, and may be various components contained in the polyester-based resin described later, A dicarboxylic acid component may be used as the shrinking component.

The polyester heat-shrinkable film may be a film whose basic unit itself is a heat-shrinkable polyester such as polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, and polyethylene naphthalate.

A preferred manufacturing method for obtaining a heat-shrinkable film roll satisfying the above requirements will be described. The heat-shrinkable film roll of the present invention biaxially stretches a film-forming step of forming a polymer while melt-extruding a polymer and an unstretched film obtained in the film-forming step at different draw ratios in directions substantially orthogonal to each other. It is manufactured by undergoing a heat-shrinkability imparting step and a rolling step of winding the resulting heat-shrinkable film. When the stretching in the direction with a large stretching ratio is called the main stretching and the stretching in the direction with a small stretching ratio is called the sub-stretching, the main stretching (the maximum shrinking direction after stretching) is the transverse direction (width direction) of the film. Since this is practical in terms of production efficiency, the case where the main stretching (the maximum shrinkage direction after stretching) is the transverse direction will be described below. Even when the main stretching is carried out in the machine direction (longitudinal direction) of the film, the stretching can be carried out according to a normal operation such as changing the stretching direction by 90 ° in the following method.

As means for incorporating the basic unit and the shrinking component into the film, there are a method in which copolymerization is carried out and this copolymer is used alone, and a method in which a homopolymer or copolymer of a different kind is blended. is there. Generally, a heat-shrinkable polyester film is obtained by blending two or more kinds of polymers having different types and compositions, or by using a plurality of copolymerization monomer components, from the viewpoint of achieving both heat shrinkability and strength. The technique of changing the characteristics of the film used according to the purpose is adopted. The present invention can employ either the method of using the copolymerized polymer alone or the method of blending, but each has the following characteristics. That is, in the method of using the copolymerized polymer alone, although there is an advantage that the composition variation of the film does not easily occur in the long film wound on the roll, it is difficult to support the industrial production of a wide variety of films. There are drawbacks. On the other hand, the blending method is widely used industrially because the characteristics of the film can be easily changed only by changing the blending ratio and it can be applied to the industrial production of a wide variety of films. In the long film thus prepared, the composition of the film is likely to change, so that the thermal shrinkage in the orthogonal direction is likely to change.

Therefore, when the blending method is adopted, the following method for suppressing the composition fluctuation of the film is adopted.

In the chip-form homogenizing blending method, usually, a plurality of raw material polymer chips having different compositions are blended in a hopper, then melt-kneaded and extruded from an extruder to form a film. For example, if there are multiple types of raw materials (for example, 3 types),
Each of the polymer chips is continuously or intermittently supplied to a plurality of (for example, three) hoppers and, if necessary, via a buffer hopper, and finally a hopper immediately before or just above the extruder (for convenience, " While mixing a plurality of types of polymer chips in a final hopper), raw material chips are quantitatively supplied to the extruder in accordance with the extrusion amount of the extruder to form a film. However, depending on the capacity or shape of the final hopper, the composition of the chips fed from the final hopper to the extruder may differ depending on the amount of chips in the final hopper and the amount of chips remaining in the final hopper. It has been found by the present inventors that the phenomenon of (1) occurs. This problem becomes remarkable especially when the shapes or specific gravities of various polymer chips are different. As a result, the heat shrinkage rate of the long film changes.

Therefore, when a heat-shrinkable polyester film roll is produced, which comprises a step of mixing a polymer used in the largest amount and one or more other polymers having a different composition from this polymer and melt-extruding the polymer, In order to obtain a film with little fluctuation, it is preferable to match the shapes of a plurality of types of polymer chips used to suppress the raw material segregation phenomenon in the final hopper.

To produce the raw material chips of the polyester film, usually, a method is employed in which, after polymerization, the material is taken out in a molten state in a strand form from a polymerization apparatus, immediately cooled with water, and then cut with a strand cutter. For this reason, the polyester chip is usually an elliptic cylinder having an elliptical cross section. At this time, as a raw material chip of another polymer to be mixed with the polymer chip having the largest usage amount, the average major axis (mm), the average minor diameter (mm) and the average chip of the cross-section ellipses of the polymer material chip having the largest usage amount are used. It has been found that the raw material segregation can be reduced by using a material within a range of ± 20% with respect to the length (mm). It is more preferable to use those having an average value within ± 15%.

If there is a difference in the size of the chips, when the mixture of chips falls in the final hopper, small chips tend to drop first. The ratio of chips increases, which causes segregation of raw materials. However, by using chips within the above range, segregation of these raw materials can be reduced, and a long film having a uniform film composition can be obtained.

An extruder is used to obtain a hopper-shaped optimized film, but optimization of the final hopper shape is also a preferable means for obtaining a long film having a uniform composition. That is, when the inclination angle of the funnel-shaped hopper is smaller than 65 °, only the small chips drop first, which causes segregation of the raw material. By using a hopper with an inclination angle of 65 ° or more, large chips can be easily dropped like small chips, and the upper end of the contents (chips) descends while maintaining a horizontal plane, so that the segregation of raw materials It is effective for reduction. A more preferable inclination angle is 70 ° or more. The inclination angle of the hopper is the angle between the funnel-shaped hypotenuse and the horizontal line segment. Multiple hoppers may be used upstream of the final hopper, in which case the tilt angle would be 6
It is preferable that the angle is 5 ° or more, more preferably 70 ° or more.

Optimization of Hopper Capacity As a means for reducing the segregation of raw materials in the hopper, it is also preferable to optimize the capacity of the hopper. The proper capacity of the hopper is, for example, within the range of 15 to 120 mass% of the discharge amount of the extruder per hour. If this hopper with too small capacity is used, stable supply of raw material is difficult, and with hopper with too large capacity, the raw material chip mixture will remain in the hopper for a long time, which may cause chip segregation. Because there is. The capacity of the hopper is 20 to 10 times the discharge amount of the extruder per hour.
The range of 0 mass% is more preferable.

Reduction of fine powder In order to obtain a long film having a uniform composition, it is also a preferable means to reduce the ratio of fine powder generated by scraping of the raw material chips used. Fine powder promotes the occurrence of raw material segregation, so remove fine powder generated in the process,
It is preferable to reduce the proportion of fine powder contained in the hopper. The ratio of the fine powder contained is preferably controlled within 1% by mass in 100% by mass of the raw material, and more preferably within 0.5% by mass throughout the entire process until the raw material chips enter the extruder. preferable. Specifically, the fine powder may be removed by, for example, a method of manufacturing chips with a strand cutter and then passing the chips through a screen, or a method of passing a raw material chip through a cyclone-type air filter when the chips are fed by air.

Any one of the above-mentioned means (especially the above-mentioned means) may be adopted if only the composition of the long film is made uniform. It is more preferable to use two or more of the four means (particularly the above means and) in combination,
It is more preferable to employ all of the above.

As described above, the composition of the long film can be obtained by using the copolymer alone, or by adopting any one of the above-mentioned means in the blending method, or by using the copolymer alone. Fluctuations can be suppressed, and fluctuations in the thermal contraction rate in the orthogonal direction can be suppressed easily.

Further, by improving the stretching conditions in addition to suppressing the compositional fluctuation of the film, it becomes easier to further suppress the fluctuation of the heat shrinkage ratio in the orthogonal direction.

Factors that cause the film surface temperature to become uniform in the stretching step, that is, the heat shrinkage rate in the film roll, are not only the above-mentioned compositional changes of the polymer components constituting the film but also the film-stretching time. There is a process variation. In order to suppress the heat shrinkage fluctuation of the long film, it is preferable to suppress the temperature fluctuation in the step of stretching the film and reduce the fluctuation range of the surface temperature of the film as much as possible.

In the case of a polyester film, for example, it is stretched in the transverse direction by using a tenter so as to have heat shrinkability, and more specifically, the transverse stretching is performed by a preheating step before stretching, a stretching step, and a stretching step. It is composed of a heat treatment step, a relaxation treatment, a re-stretching treatment step and the like. Then, in the preliminary heating step in the transverse stretching, the transverse stretching step and the heat treatment step after the transverse stretching, the fluctuation range of the surface temperature of the film measured at an arbitrary point is within an average temperature ± 1 ° C, preferably an average temperature ± 0.5 ° C. If you control within
Since the film can be transversely stretched and heat treated at substantially the same temperature over the entire length of the film, the heat shrinkage behavior becomes uniform. Even in the relaxation treatment and re-stretching treatment step, as in the preliminary heating step and the like,
It is preferable to reduce the fluctuation range of the surface temperature of the film.

In order to reduce the fluctuation of the film surface temperature, for example, a wind speed fluctuation suppressing equipment equipped with an inverter so that the wind speed of the hot air for heating the film can be controlled is used, or the heat source is 500 kPa or less (5 kgf / cm ²
It is advisable to use equipment that can suppress the temperature fluctuations of the hot air by using the low pressure steam described below).

The fluctuation range of the surface temperature of the film measured at an arbitrary point means that the film surface temperature is continuously measured during the production of the film, for example, at a point 2 m after the transverse stretching step, for example, an infrared type non-temperature. The fluctuation range when measured with a contact surface thermometer. Since the average temperature can be calculated at the time when the film production for one roll is completed, if the fluctuation range of the film surface temperature is within ± 1 ° C of the average temperature, the film can be horizontally moved under the same condition over the entire length of the steady region of the film. Since it is stretched, the fluctuation of the heat shrinkage is also small.

A preferred production example of the polyester film will be specifically described by taking the case of using the above means as an example, but the following specific example can be applied to the case of using other means. First, the raw material chips whose size is controlled to satisfy the above means are dried using a dryer such as a hopper dryer, a paddle dryer, or a vacuum dryer,
Extrude into a film at a temperature of 300 ° C. Alternatively, the undried polyester raw material is similarly extruded into a film shape while removing water in a vent type extruder. Any existing method such as a T-die method or a tubular method may be adopted for extrusion. After extrusion, the film is cooled (especially rapidly cooled) with a casting roll to obtain an unstretched film. The "unstretched film" also includes a film to which a tension necessary for feeding the film acts.

The unstretched film is stretched. The stretching treatment may be performed continuously after cooling with the above casting roll or the like, or may be performed after being once wound into a roll after cooling.

Further, focusing on making the thickness distribution of the heat-shrinkable polyester film uniform, it is preferable to carry out a preliminary heating step prior to the stretching step when stretching in the transverse direction using a tenter or the like. In this preheating step, the coefficient of thermal conductivity is 0.00544 J / cm ² · sec ·
℃ (0.0013 calories / cm ² · sec · ° C) or less, low wind speed and film surface temperature Tg + 0
It is preferable to perform heating until the temperature reaches a certain temperature within the range of ° C to Tg + 60 ° C (Tg means the glass transition temperature of the film. The same applies hereinafter).

Stretching in the transverse direction is from "Tg-20 ° C" to "Tg".
2.3 to 7.3 at a predetermined temperature within the range of g + 40 ° C.
Stretching twice, preferably 2.5 to 6.0 times. afterwards,
At a predetermined temperature within the range of 60 ° C to 110 ° C, heat treatment is performed while stretching 0 to 15% or relaxing 0 to 15%,
If necessary, further heat treatment is performed at a predetermined temperature within the range of 40 ° C to 100 ° C to obtain a heat-shrinkable polyester film. In this transverse stretching step, it is preferable to use equipment capable of reducing the fluctuation of the film surface temperature as described above.

The internal heat generation of the film due to stretching is suppressed,
Focusing on reducing the temperature unevenness of the film, the heat transfer coefficient in the stretching process is 0.00377 J / cm ² · sec.
-It is preferable to set the temperature at or above (0.0009 calories / cm ² · sec · ° C). 0.00544-0.008
37 J / cm ² · sec · ° C (0.0013-0.00
20 calories / cm ² · sec · ° C) is more preferable.

In the present invention, in order to prevent vertical shrinkage to a higher degree, stretching is performed not only in the transverse direction but also in the longitudinal direction.
The longitudinal stretching conditions will be described later.

As the polyester resin, as a dicarboxylic acid component, one or more kinds of aromatic dicarboxylic acid, aliphatic dicarboxylic acid and ester-forming derivatives thereof are used, and a known (copolymerization) polycondensation with a polyhydric alcohol component is carried out. Polyester can be used. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, naphthalene-
1,4- or -2,6-dicarboxylic acid, 5-sodium sulfoisophthalic acid and the like can be mentioned. Examples of the aliphatic dicarboxylic acid include dimer acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid and succinic acid. In addition, an oxycarboxylic acid such as p-oxybenzoic acid or a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic dianhydride may be used in combination as necessary. Among them, terephthalic acid, isophthalic acid and naphthalene-1,4- or -2,6-dicarboxylic acid are preferable. Examples of these ester derivatives include derivatives such as dialkyl esters, diaryl esters and acid halides.

As the polyhydric alcohol component, ethylene glycol, diethylene glycol, dimer diol,
Propylene glycol, triethylene glycol, 1,
4-butanediol, neopentyl glycol, 1,4
-Cyclohexanedimethanol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-
1,3-propanediol, 1,9-nonanediol,
Alkylene glycols such as 1,10-decanediol,
Examples thereof include alkylene oxide adducts of bisphenol compounds or their derivatives, trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, polyethylene glycol and the like.
Further, ε-caprolactone can also be used for the synthesis of polyester.

The polyester raw materials constituting the polyester heat-shrinkable film may be used alone or as a mixture of two or more kinds. When used alone, homopolyesters other than polyethylene terephthalate such as polybutylene terephthalate, polycyclohexylene dimethyl terephthalate and polyethylene naphthalate are preferred. This is because polyethylene terephthalate alone does not exhibit heat shrinkability.

As the basic unit of polyester, an ethylene terephthalate unit is preferable in consideration of the tear resistance, strength, heat resistance and the like of the film. However, if the ethylene terephthalate unit is the basic unit,
Since this unit does not have heat shrinkability as described above, it is necessary to coexist a component (other component) other than ethylene glycol and terephthalic acid. These other components are useful for reducing the crystallinity of the ethylene terephthalate unit and making the film heat-shrinkable. Preferred other components (heat-shrinkable components) include 1,4-cyclohexanedimethanol, neopentyl glycol, 1,4-butanediol, propylene glycol and the like.

When the ethylene terephthalate unit is used as a basic unit, it is preferable to use a blend of two or more polyesters having different Tg from the viewpoint of heat shrinkage characteristics. It is preferable to use polyethylene terephthalate and a copolyester (which may be two or more kinds) in mixture, but a combination of the copolyesters may be used. In any case, it is preferable that the ethylene terephthalate unit is present in an amount of 50 mol% or more in order to develop the heat resistance and strength of the film. 55 mol% or more is more preferable, and 60 mol% or more is further preferable.

Further, polybutylene terephthalate, polycyclohexylene dimethyl terephthalate, polyethylene naphthalate may be combined with each other, or these may be used in combination with other copolymer polyesters.

The most preferable in terms of heat shrinkability is (i)
It is a blend type of three kinds of polymers of polyethylene terephthalate, (ii) polybutylene terephthalate, and (iii) a copolymerized polyester composed of terephthalic acid and a mixed diol component of ethylene glycol and neopentyl glycol. Neopentyl glycol has the effect of amorphizing the polyester and can enhance the heat shrinkability, and 1,4-butanediol lowers the glass transition temperature of the film, and exerts heat shrinkability at low temperatures. Because it helps. When a polyhydric alcohol component other than ethylene glycol or a polycarboxylic acid component other than terephthalic acid is used, each component is 100 mol%
It is preferable to use 5 mol% or more. 7 mol% or more is more preferable, and 9 mol% or more is further preferable. When two or more polyesters are used in combination, as described above, it is preferable from the viewpoint of production efficiency to blend the chips of each polymer in the hopper.

Polyester can be produced by melt polymerization by a conventional method, but dicarboxylic acids and glycols are directly reacted with each other to polycondense the obtained oligomer.
Examples include so-called direct polymerization method, so-called transesterification method in which dimethyl ester of dicarboxylic acid and glycol are subjected to transesterification reaction and then polycondensation, and any production method can be applied. Further, it may be a polyester obtained by another polymerization method. The degree of polymerization of polyester is 0.3 to 1.3d in terms of intrinsic viscosity.
It is preferably 1 / g.

In order to prevent inconveniences such as coloring and gel formation in polyester, in addition to polymerization catalysts such as antimony oxide, germanium oxide and titanium compounds, magnesium salts such as magnesium acetate and magnesium chloride, calcium acetate, Ca salts such as calcium chloride, manganese acetate,
Mn salts such as manganese chloride, Zn such as zinc chloride and zinc acetate
Cobalt such as salt, cobalt chloride, cobalt acetate, etc. is added to the polyester as metal ion of 300 ppm, respectively.
(Mass basis, the same applies hereinafter) Phosphoric acid or phosphoric acid ester derivatives such as phosphoric acid trimethyl ester and phosphoric acid triethyl ester may be added in an amount of 200 ppm or less in terms of phosphorus (P).

The total amount of metal ions other than the above polymerization catalyst was 300 ppm with respect to polyester, and the P amount was 200 pp.
When it exceeds m, not only the coloring of the polymer becomes remarkable, but
It is not preferable because the heat resistance and hydrolysis resistance of the polymer are significantly lowered.

At this time, in terms of heat resistance, hydrolysis resistance, etc., the mass ratio (P / M) of the total amount of P (P) and the total amount of metal ions (M) is 0.4 to 1.0. Is preferred.
If the mass ratio (P / M) is less than 0.4 or exceeds 1.0, the film may be colored or coarse particles may be mixed into the film, which is not preferable.

The timing of addition of the above metal ions and phosphoric acid and its derivatives is not particularly limited. Generally, metal ions are charged at the time of charging the raw materials, that is, before transesterification or esterification, and phosphoric acids are subjected to a polycondensation reaction. It is preferably added before.

If necessary, fine particles of silica, titanium dioxide, kaolin, calcium carbonate or the like may be added, and further, an antioxidant, an ultraviolet absorber, an antistatic agent,
Colorants, antibacterial agents, etc. can also be added.

In the case of heat shrinking at a temperature of about 85 to 90 ° C. by suppressing the compositional variation of the film and the thermal shrinkage as described above, for example,
It is possible to suppress the variation of the heat shrinkage ratio in the orthogonal direction. However, in the case of heat shrinking at a temperature of 90 to 95 ° C., in order to suppress the variation of the heat shrinkage ratio in the orthogonal direction within the range of the present invention,
Stretching is always performed in the orthogonal direction, and it is necessary to adopt a predetermined stretching temperature in the stretching in the orthogonal direction.

The case where the maximum contraction direction is the lateral direction (width direction) of the film [hence, the case where the direction orthogonal to the maximum contraction direction is the longitudinal direction (longitudinal direction) of the film] will be described below.

That is, as described above, the transverse stretching is performed at a predetermined temperature within the range of "Tg-20 ° C" to "Tg + 40 ° C", while the longitudinal stretching is "Tg + 50 ° C".
Perform at the above temperature. Longitudinal stretching at such a relatively high temperature can highly suppress the variation of the heat shrinkage ratio in the orthogonal direction, so that vertical shrinkage can be prevented even when heat shrinked at a temperature of 90 to 95 ° C, and the appearance after shrinkage is good. You can A preferred longitudinal stretching temperature is, for example, about “Tg + 55 ° C.” or higher (particularly, “Tg + 60 ° C.” or higher). The upper limit of the longitudinal stretching temperature is, for example, about "melting point-15 ° C" or less in the case of a polyester film showing a melting point, and "Tg + 130 ° C" in the case of a polyester film showing no melting point.
It is about the following. The longitudinal stretching temperature means the highest temperature reached on the surface of the film in the longitudinal stretching section.

The stretching ratio in the longitudinal direction is smaller than that in transverse stretching, and is, for example, about 1.05 to 1.5 times, preferably about 1.07 to 1.5 times. If the stretching ratio is made too large, the heat shrinkage ratio in the machine direction (direction orthogonal to the maximum shrinkage direction) becomes too large.

That is, the film roll of the present invention is manufactured by performing stretching (biaxial stretching) in both the transverse direction and the longitudinal direction, and performing the longitudinal stretching at a predetermined temperature. As biaxial stretching, sequential biaxial stretching is adopted. By adopting sequential biaxial stretching, transverse stretching and longitudinal stretching can be performed at different temperatures. In the sequential biaxial stretching, after stretching in the transverse direction and the longitudinal direction, stretching (re-stretching) in the transverse direction and / or the longitudinal direction may be performed again.
The order of stretching is not particularly limited, and any method such as vertical / horizontal, horizontal / vertical, vertical / horizontal / vertical, horizontal / vertical / horizontal may be used. Further, the transverse stretching and the longitudinal stretching may be one-stage stretching or multi-stage stretching of two or more stages. After the longitudinal stretching, it is preferable to perform a relaxation treatment and / or a heat treatment as in the case of the transverse stretching.

In the longitudinal stretching, the stretching speed is, for example,
20 times / minute or more (preferably 25 times / minute or more, more preferably 30 times / minute or more), 1,000 times / minute or less (preferably 900 times / minute or less, more preferably 800 times / minute or less) It is desirable to control the range. If the stretching speed is too fast, insufficient heating of the film is likely to occur, and if the stretching speed is too slow, productivity is reduced.

The stretching speed can be calculated according to the following formula.

Stretching speed = L ₁ / T ₁ [wherein, L ₁ represents the stretching ratio, T ₁ represents the time (minutes) required to give the stretching ratio on the left] The longitudinally stretched film was
Without cooling to Tg or lower, the same temperature range as the above longitudinal stretching temperature (for example, Tg + 50 ° C. or higher) is passed,
It is preferable to perform relaxation treatment. If the longitudinally stretched film is once cooled and then reheated for relaxation treatment, thermal crystallization proceeds in the case of a crystalline film. for that reason,
When the film is transversely stretched after that, the stretching stress at the time of transverse stretching is increased, the stretchability is deteriorated, and the film is easily broken.

The passage time in the predetermined temperature zone in the relaxation treatment is, for example, 0.1 seconds or more, preferably 0.2 seconds or more. If the relaxation time is too short, the relaxation effect cannot be obtained. The relaxation rate is, for example, 20% or less, preferably 15% or less. If the relaxation rate is too large, the film becomes loose in the longitudinal direction, the film running becomes unstable such as meandering, and scratches may be induced.

The relaxation rate is a value calculated according to the following equation.

Relaxation rate (%) = (1−S ₂ / S ₁ ) × 100 (In the formula, S ₁ represents the traveling speed of the film on the downstream side when the film is stretched while changing the traveling speed of the film. S ₂ Indicates the running speed of the film after stretching) When heating to the above-mentioned predetermined temperature in longitudinal stretching, if necessary, it may be preheated to a temperature below the above-mentioned predetermined temperature. The preheating temperature is, for example, 1 than the predetermined temperature.
It is a low temperature of about 0 to 80 ° C.

Various heating means can be adopted for raising the temperature to a predetermined temperature during preheating, longitudinal stretching (main heating), relaxation treatment, etc., but preferably a heating roll and / or a heater (infrared heater). Etc.) is used.

As the heating roll, for example, a heating roll made of a metal material having a surface hard chrome plating (hereinafter referred to as a chrome plating roll), a heating roll made of a ceramic material (hereinafter referred to as a ceramic roll), fluorine Heating roll made of resin material (hereinafter,
A fluororesin roll), a heating roll made of a silicone rubber material (hereinafter referred to as a silicone rubber roll), or the like can be selected. Especially, it is desirable to use chrome-plated rolls, fluororesin rolls, etc. during preheating, and ceramic rolls, silicon rubber rolls, etc. when preheated to a prescribed temperature (main heating) or during relaxation treatment. It is desirable to do. The chrome plating roll and the fluororesin roll are excellent in transferring heat to the film, and can efficiently preheat the film. On the other hand, ceramic rolls and silicon rubber rolls are excellent in releasability, and can maintain good releasability even when the film softens and easily sticks during the main heating or relaxation treatment. For example, after preheating a film using a roll group for preheating consisting of a chrome plating roll and / or a fluororesin roll, one or more main heating rolls consisting of a ceramic roll and / or a silicon rubber roll are used. It is desirable to raise the temperature of the film to a predetermined temperature. The preheating roll may be a free rotation type or a drive type. The main heating roll is usually of a driving type. The film thus heated to a predetermined temperature can be longitudinally stretched by utilizing the speed difference between the main heating roll and the stretching roll installed downstream thereof. Also in the relaxation treatment step, it is desirable to maintain the film at a predetermined temperature using one or a plurality of heating rolls made of a ceramic roll and / or a silicon rubber roll. The relaxation treatment can be performed by utilizing the speed difference between the stretching roll installed downstream of the stretching roll.

As the infrared heater, a far infrared heater,
A near infrared heater (in particular, a condensing type near infrared heater) can be used, and these heaters can be used alone or in combination.

As for the heating by the heating roll and the heating by the heater, only one of them may be adopted or both of them may be combined. For example, preliminary heating may be performed using a heating roll, and main heating (longitudinal stretching) and relaxation treatment may be performed using a heater. In this case, a drive roll is adopted as the most downstream roll that constitutes the heating roll group, and longitudinal stretching and subsequent relaxation treatment are performed by utilizing the speed difference between the stretching roll installed downstream thereof. You can A heating heater may be used as an auxiliary when performing preheating or main heating using a heating roll.

The longitudinal traveling direction of the film is preferably the vertical direction. Although it is usual that the direction of travel of the film is horizontal, in the present invention, since the longitudinal stretching is carried out at a high temperature, the rigidity of the film decreases. Therefore, when the film is advanced in the horizontal direction, the film hangs downward and easily adheres to the roll, making stable film formation difficult.

The heat-shrinkable polyester film roll of the present invention is preferably a roll of a heat-shrinkable film having a width of 0.2 m or more wound around a winding core (core) of 300 m or more in length. A roll of a film having a width of less than 0.2 m has a low industrial utility value, and a film roll having a length of less than 300 m has a short winding length of the film, and thus the film has a full length. Since the change in heat shrinkage is small, the effect of the present invention is difficult to be exhibited. The width of the heat-shrinkable film roll is more preferably 0.3 m or more, further preferably 0.4 m or more. The length of the heat-shrinkable film wound on the roll is more preferably 400 m or more, further preferably 500 m or more.

The upper limits of the width and the winding length of the film roll are not particularly limited, but for ease of handling,
Generally, the width is 1.5m or less, and the roll length is film thickness 45μ.
In the case of m, it is preferably 6000 m or less. As the winding core, a plastic core of 3 inches, 6 inches, 8 inches, or the like, or a metal core can be used.

The thickness of the film constituting the heat-shrinkable polyester film roll of the present invention is not particularly limited, but for example, the heat-shrinkable film for labels is preferably 10 to 200 μm, and 20 to 100 μm.
Is more preferable.

[0087]

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modifications made within the scope of the present invention are included in the present invention. Be done. The methods for measuring the physical properties of the film rolls obtained in Examples and Comparative Examples are as follows.

(1) Confirmation of steady region and setting of sample cut-out portion Length 1000 m obtained in Examples and Comparative Examples described later
For the film roll on which the film of No. 2 was wound, 5 point samples were cut out at 20 m intervals from the second end (winding end) of the film, and 2 from the first end (winding start) of the film.
Five samples were cut out at an interval of 20 m from the inner part of 00 m toward the first end, and the maximum heat shrinkage stress value in the maximum shrinkage direction of these samples was measured (described later). The maximum heat shrinkage stress value of each sample was within the range of 3 MPa. Moreover, during the production of the film, the production / stretching process was stable. Therefore, it was confirmed that each film roll corresponds to the constant region over the entire length of the film.

In such a film roll, a sample was cut out from the steady region and the following physical properties (2) to (9) were measured. In measurements other than the following physical properties (3) "solvent adhesion strength" and (8) and (9) "shrinkage finish and vertical sink defect rate", the first sample cut-out portion was the second end portion of the film (rolled film). The length was 0 m from the end, and the final sample cutout part was the first end of the film (0 m from the start of winding). Samples were collected from 11 sample cutout parts in total. Then, 10 samples were cut out from each sample cutout part, and the average value of the physical properties of the 10 samples in each sample cutout part was taken as the physical property value of the sample in the cutout part [(3) "solvent adhesion strength"] , (8) and (9) “Shrinking finish and vertical sink defect rate” will be described in detail in each measurement item].

(2) Component composition Each sample was dissolved in a solvent in which chloroform D (manufactured by Eurysop Co.) and trifluoroacetic acid D1 (manufactured by Eurysop Co.) were mixed at a ratio of 10: 1 (volume ratio) to prepare a sample solution. NMR (“GEMINI-200”; Varian
(Manufactured by K.K.) was used to measure the proton NMR of the sample solution under the measurement conditions of a temperature of 23 ° C. and an integration number of 64 times. In the NMR measurement, the peak intensity of a predetermined proton was calculated, and the amount of ethylene glycol, neopentyl glycol, or 1,4-butanediol in 100 mol% of the polyhydric alcohol component was measured. The most abundant alcohol component in the following examples and comparative examples was ethylene glycol. Among the components other than ethylene glycol, the variation in the content ratio of the most abundant alcohol component (the most secondary alcohol component) and the second most abundant alcohol component (the second secondary alcohol component) (average value, The maximum value and the minimum value) were investigated.

(3) Solvent adhesive strength: The film of the film roll has a width of 273 mm over the entire length.
Slit into, roll again and roll at temperature 30 ± 1
The sample was stored for 250 hours in an environment controlled at 85 ° C. and a relative humidity of 85 ± 2%. Next, this is a grass color from Toyo Ink Mfg. Co.,
After printing three colors with gold and white inks, use a tube forming machine and use 1,3-dioxolane with a width of 2 ± 1mm on one side of both slit ends of the film so as not to adhere to the edge portion. Apply (Apply amount: 3.0 ± 0.3g
/ Mm ² ), the film was immediately rolled, both slit ends were overlapped and bonded, and processed into a tube (processing speed:
80 mm / min). The tube was rolled into a roll in a flatly crushed state.

Samples are cut out from the above tube roll at intervals of about 100 m. The first sample cut-out portion is the winding end portion (0 m from the winding end) of the tube.
The final cutout portion was the winding start portion (0 m from the winding start) of the tube, and 11 samples were collected in total. The tube-shaped sample obtained from each sample cut-out part was cut open so that the adhesion location was at the center, and a film-shaped sample was obtained. From this film sample, length 100 mm, width 1
Cut out a 5 mm film-like test piece (n = 10),
This film-shaped test piece was subjected to a tensile tester ("STM-" manufactured by Baldwin Co., Ltd.) in which the distance between chucks was set to 50 mm.
T ”) so that the solvent-bonded portion is located at the center of the chucks, and the temperature is 23 ° C. and the pulling speed is 200 mm /
A tensile test is performed under the condition of minutes, the peel strength of the bonded portion is measured, and this is taken as the solvent bonding strength.

The variation (average value, maximum value, minimum value) among samples of the above-mentioned solvent adhesive strength was examined.

(4) A glass transition temperature sample of 10 ± 1 mg was heated at a temperature of 300 ° C. for 2 minutes, immediately put in liquid nitrogen and rapidly cooled, and then a DSC apparatus (model: DSC220) manufactured by Seiko Denshi Kogyo Co., Ltd. was used. Then, the temperature was raised from -40 ° C to 300 ° C at a rate of 20 ° C / min, the DSC curve was measured, and the glass transition temperature (° C) was determined. The glass transition temperature (Tg) was the intersection of the tangent lines drawn before and after the endothermic start curve in the DSC curve.

The variation (average value, maximum value, minimum value) between samples of the above glass transition temperature was examined.

(5) The heat shrinkage ratio of the film in the maximum shrinkage direction at each hot water temperature (85 ° C. or 95 ° C.) is set so as to be along the longitudinal direction and the direction orthogonal thereto.
Cut into 0 cm x 10 cm squares, 85 ° C ± 0.5 ° C
Alternatively, the sample is immersed in warm water of 95 ° C ± 0.5 ° C for 10 seconds under no load for heat shrinkage, and immediately immersed in water of 25 ° C ± 0.5 ° C for 10 seconds. The length in the direction was measured and determined according to the following formula. Thermal shrinkage (%) = 100 × (length before shrinkage−length after shrinkage) ÷ (length before shrinkage) The direction with the largest shrinkage was defined as the maximum shrinkage direction.

The variation (average value, maximum value, minimum value) between samples of the heat shrinkage ratio in the maximum shrinkage direction was examined.

(6) Thermal shrinkage in the direction orthogonal to the maximum shrinkage direction at each hot water temperature (85 ° C. or 95 ° C.) In the measurement of the thermal shrinkage ratio in the maximum shrinkage direction in (5) above,
The heat shrinkage rate was also obtained in the direction orthogonal to the maximum shrinkage direction.

The variation (average value, maximum value, minimum value) between samples of the heat shrinkage ratio in the orthogonal direction was examined.

(7) Maximum heat shrinkage stress value A sample having a length of 200 mm and a width of 20 mm in the maximum shrinkage direction was prepared, and in a heating furnace of a tensile tester (“Tensilon” manufactured by Toyo Seiki) equipped with a hot air heating furnace. Is heated to 90 ℃,
Stop blowing air and set the sample in the heating furnace. The distance between chucks is 100 mm (constant). The door of the heating furnace is quickly closed, and the air blow (90 ° C., blowing speed 5 m / s) is restarted to detect and measure the heat shrinkage stress. The maximum value was read from the chart and this was taken as the maximum heat shrinkage stress value (MPa).

The variation (average value, maximum value, minimum value) between samples of the maximum heat shrinkage stress value was examined.

(8) Shrinkage finish when shrinkage temperature = 80 to 90 ° C. and vertical shrinkage defect rate Of the tubes prepared in the above (3), all the parts of the tube not used for solvent adhesive strength measurement were cut. Then, a heat-shrinkable film label was prepared. About 1/2 amount of this heat-shrinkable film label was heat-shrinked into the bottle to determine shrink finish quality and vertical sink defect rate when the shrink temperature was set to 80 to 90 ° C.

That is, a 0.9 L square PET bottle was fitted with a heat-shrinkable film label, and a steam tunnel (model: SH-1500-L) manufactured by Fuji Astec Co., Ltd.
The label (about 1/2 amount) was passed under the condition of tunnel passage time of 10 seconds, 1 zone temperature / 2 zone temperature = 80 ° C./90° C., and shrink finish property and vertical sink defect rate were determined as follows. .

[Shrinkage Finishability] Shrinkage finishability was evaluated on a scale of five. 5: Best finish quality 4: Good finish quality 3: Some defects (within 2 places) 2: There are defects (3 to 5 places) 1: Many defects (6 or more places) Here, defects are wrinkles and label edges. Folds, color spots, and insufficient shrinkage. A grade of 4 or more was a passing level and a grade of 3 or less was defective, and the shrinkage finish defective rate (%) was obtained according to the following formula. The results are also shown in Table 7. Shrinkage finish defect rate = 100 × defective sample number / total sample number [vertical sink defect rate] The vertical sink defect rate was obtained as follows. First, the length in the vertical direction of the label after shrinkage is measured for the total amount of the label-attached bottles, and the difference between the length (Lmax) and the length (Lmin) of the shortest part (Lmin) in the vertical direction is measured for each bottle ( Lmax-Lmin), that is, vertical sink (L). In addition, Lmax of most of the labels matches the length of the label before contraction of 110 mm (no contraction). The average value (L) of all the label-equipped bottles (L)
Calculate a). The difference between the average value (La) of vertical sinking and the vertical sinking (L) of each label is within ± 1.0 mm as a pass. That is, if | La-L | is 1.0 mm or less, it passes 1.
Those exceeding 0 mm are regarded as defective. The vertical sink defect rate (%) is calculated from the following formula. Vertical shrinkage defect rate = 100 × number of defective samples / total number of samples (9) Shrinkage finish property when shrinkage temperature is set to 90 to 95 ° C. and vertical shrinkage defect rate Of the heat-shrinkable film labels obtained in (8) above. Tunnel remaining time = 6 using all remaining amount (about 1/2 amount)
Second, 1 zone temperature / 2 zones temperature = 90 ° C./95° C., except that shrinkage temperature = 90
The shrinkage finish property and vertical sink defect rate when set to ˜95 ° C. were evaluated.

Synthesis Example 1 (Synthesis of Polyester) 100 mol% of dimethyl terephthalate (DMT) as a dicarboxylic acid component was placed in a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux type cooler.
And ethylene glycol (EG) as the diol component
68 mol% and neopentyl glycol (NPG) 32 mol% were charged so that the polyhydric alcohol would be 2.2 times the molar ratio of the methyl ester, and 0.05 mol% of zinc acetate as the transesterification catalyst (acid component )) And 0.025 mol% of antimony trioxide (based on the acid component) as a polycondensation catalyst, and transesterification was carried out while distilling the produced methanol out of the system. After that, 280 ℃
The polycondensation reaction was performed under reduced pressure of 26.7 Pa. The obtained polyester in a molten state was taken out from the polymerization apparatus in a strand form, immediately cooled with water, and then cut with a strand cutter to obtain a raw material chip A. In addition, the cutting conditions were changed to prepare a slightly smaller chip for the comparative example. This was used as raw material chip B. The intrinsic viscosity of Chip A and Chip B was 0.70 dl / g.

The limiting viscosity was 25 g of phenol / tetrachloroethane = 3 /
After dissolving in a mixed solvent of 2 (mass ratio), it was measured at 30 ± 0.1 ° C. with an Ostwald viscometer. The intrinsic viscosity [η] is
It is calculated by the following equation (Huggins equation).

[0107]

[Equation 1]

Here, η _{sp is the} specific viscosity, t _{0 is} the drop time of the solvent using the Ostwald viscometer, t is the drop time of the chip solution using the Oswald viscometer, and C is the concentration of the chip solution. In the actual measurement, the intrinsic viscosity was calculated according to the following approximate equation with k = 0.375 in the Huggins equation.

[0109]

[Equation 2]

Where η _r is the relative viscosity.

Synthetic Example 2 By the same method as in Synthetic Example 1, polyester raw material chips C to D having the composition shown in Table 1 were obtained. BD in the table
Is an abbreviation for 1,4-butanediol. The intrinsic viscosity of each polyester chip is 1.20 dl / g for chip C,
Chip D was 1.20 dl / g.

Comparative Example 1 Four hoppers of the same shape having a capacity of 400 kg of raw material chips and an inclination angle of 60 ° were arranged in series. On the other hand, each chip obtained in the above synthesis example was separately predried. The chips B, C, and D are supplied to the most upstream hopper at the ratios shown in Table 1 (chip B = 60 mass%, chip C = 25 mass%, chip E = 15 mass%), and the second, third The hopper was moved to each of the fourth hopper (final hopper; hopper immediately above the extruder). Melt extrusion was performed at 280 ° C. with a single-screw extruder (discharging amount = 450 kg / hour), and then rapidly cooled to obtain an unstretched film having a thickness of 180 μm.

The unstretched film was heated at a temperature of 105 ° C. for 10
After preheating for 2 seconds, use a tenter to move it in the horizontal direction at 78 ° C (Tg + 1
The film was stretched 4.0 times at 3 ° C.) and then heat-treated at 80 ° C. for 10 seconds to continuously form a heat-shrinkable polyester film having a thickness of 45 μm over 1000 m or more. The fluctuation range of the film surface temperature is the average temperature ± in the preheating process.
The temperature was 1.0 ° C., the average temperature was ± 2.5 ° C. in the stretching step, and the average temperature was ± 2.0 ° C. in the heat treatment step.

Each of the obtained films was 0.4 m in width and 1 in length.
After slitting to 000 m, it was wound on a 3-inch paper tube to obtain a heat-shrinkable film roll. The surface temperature of the film was measured using an infrared non-contact surface thermometer (the same applies to the following Examples and Comparative Examples).

Comparative Examples 2-3 Each of the chips obtained in the above synthesis example was separately predried.
Ratios shown in Table 1 (chip A = 60 mass%, chip D =
25% by mass, chips E = 15% by mass), each chip was continuously and separately fed to a hopper directly above the extruder with a metering screw feeder, and mixed in this hopper.
Melt extrude with a single screw extruder at 0 ° C, then quench,
An unstretched film having a thickness of 180 μm was obtained. The hopper had a capacity of containing 150 kg of raw material chips, and the discharge rate of the extruder was 450 kg per hour. The inclination angle of the hopper was 70 °.

Two unstretched film rolls were obtained by dividing the above unstretched film into two equal parts in the lengthwise direction. For each unstretched film, after preheating at 105 ° C. for 10 seconds,
Stretched 4.0 times in the transverse direction at 78 ° C with a tenter, then 8
Heat treatment was performed at 0 ° C. for 10 seconds to continuously form a heat-shrinkable polyester film having a thickness of 45 μm over 1000 m or more. Here, in Comparative Example 2, the fluctuation range of the film surface temperature when the film is continuously manufactured is the average temperature ± 1.0 ° C in the preheating step, the average temperature ± 2.5 ° C in the stretching step, and the average in the heat treatment step. Temperature ± 2.0 ° C
Was within the range. Further, in Comparative Example 3, the fluctuation range of the film surface temperature was changed to the average temperature ± 0.5 in the preheating step.
C., the average temperature ± 0.4 ° C. in the stretching step, and the average temperature ± 0.5 ° C. in the heat treatment step.

Each of the obtained films was 0.4 m in width and 1 in length.
After slitting to 000 m, it was wound on a 3-inch paper tube to obtain a heat-shrinkable film roll.

Example 1 An unstretched film roll was obtained in the same manner as in Comparative Example 3 above.

The unstretched film was preheated to a temperature of 85 ° C. (a temperature 55 ° C. lower than the following longitudinal stretching temperature) by roll heating in a longitudinal stretching machine, and then a film temperature of 140 ° C. (using a condensing infrared heater). Tg + 75 ° C.). This heating film has a draw ratio of 1.
2. The film was drawn at a drawing speed of 90 times / min, immediately heated on a heating roll at a film temperature of 150 ° C. for 2 seconds to be relaxed by 5%, and further cooled on a cooling roll to a film temperature of 30 ° C. A silicon rubber roll was used as a roll that was in contact with the film when heated by a condensing infrared heater, a ceramics roll was used as a heat treatment roll after stretching, and a chrome plating roll was used as a cooling roll. Nip rolls before and after stretching were not used.

Then, transverse stretching and heat treatment were carried out in the same manner as in Comparative Example 3 to continuously form a heat-shrinkable polyester film having a thickness of 45 μm over 1000 m or more. The fluctuation range of the film surface temperature during transverse stretching is the same as in Comparative Example 3.

The film thus obtained was 0.4 m wide and 10 long.
The heat-shrinkable film roll was obtained by slitting it to 00 m and winding it up on a 3-inch paper tube.

The physical properties of the heat-shrinkable film rolls obtained in the respective Examples and Comparative Examples are shown in Tables 2 to 10 below.

[0123]

[Table 1]

[0124]

[Table 2]

[0125]

[Table 3]

[0126]

[Table 4]

[0127]

[Table 5]

[0128]

[Table 6]

[0129]

[Table 7]

[0130]

[Table 8]

[0131]

[Table 9]

[0132]

[Table 10]

As is clear from Tables 1 to 8, as compared with Comparative Example 1 in which the chip shape, hopper capacity, etc. are improper and raw material segregation is likely to occur, Comparative Examples 2 to 3 and Example 1 have different film compositions. Fluctuation (variation of most secondary alcohol components,
The fluctuation of the second secondary alcohol component) can be suppressed, the fluctuation of the solvent adhesive strength can be suppressed, and the fluctuation of the glass transition temperature can be suppressed. As a result, it is possible to improve the shrink finish property when the shrink temperature is 80 to 90 ° C (see Table 7).

Particularly, in Comparative Example 3 and Example 1, since the surface temperature of the film in the transverse stretching step is precisely controlled, the fluctuation of the maximum heat shrinkage stress value and the heat shrinkage in the maximum shrinkage direction at the temperature of 85 ° C. It is possible to suppress the fluctuation of the rate and the fluctuation of the heat shrinkage rate in the orthogonal direction when the temperature is 85 ° C. As a result, it is possible to enhance the shrink finish property when the shrink temperature = 80 to 90 ° C. and suppress the occurrence of vertical sinking (see Table 8).

However, as is clear from Tables 9 to 10,
In Comparative Example 3, the thermal shrinkage in the orthogonal direction fluctuates when measured at a temperature of 95 ° C., and if the shrinking temperature is set to 90 to 95 ° C., suppression of vertical sinking becomes insufficient. On the other hand, in Example 1, since the longitudinal stretching was performed under predetermined conditions, the thermal shrinkage variation in the orthogonal direction was suppressed even when measured at a temperature of 95 ° C, and the shrinkage temperature was 90 to 95 ° C. It is also possible to control vertical sinking. Therefore, the tunnel passage time in heat contraction is about 10 seconds (contraction temperature = 80 to 90).
Approximately 6 seconds (shrink temperature = 90 to 95)
In the case of about ℃), it is possible to improve productivity.

[0136]

EFFECT OF THE INVENTION The heat-shrinkable film roll of the present invention has little fluctuation in heat shrinkage in the direction orthogonal to the maximum shrinkage direction of the long film wound around the film roll. In particular, even if the heat shrink temperature is set to 95 ° C., there is little variation in the heat shrink rate in the orthogonal direction. Therefore, even when the object to be packaged (bottle or the like) is heat-shrinked at a relatively high temperature of about 90 to 95 ° C., it is possible to reduce the occurrence of appearance defects due to variations in vertical sinking. Therefore, the heat shrinkage can be performed at a higher speed, and the productivity can be improved.

Further, the method for producing a heat-shrinkable film roll of the present invention can easily reduce the fluctuation of the heat shrinkage rate (heat shrinkage rate at a temperature of 95 ° C. in the direction orthogonal to the maximum shrinkage direction) of the long film. And is very useful in industrial production.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Takekawa             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Katsuya Ito             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Shigeru Yoneda             Toyobo, 2-8, Dojimahama, Kita-ku, Osaka-shi             Koki Co., Ltd. (72) Inventor Katsuhiko Nose             Toyobo, 2-8, Dojimahama, Kita-ku, Osaka-shi             Koki Co., Ltd. F-term (reference) 4F210 AA24 AE01 AG01 AH54 AM34                       AR06 AR07 AR08 AR12 QA02                       QA03 QC06 QD13 QD34 QD36                       QG01 QG18 QW05 RA03 RA05                       RC02 RG02 RG04 RG43

Claims (9)

[Claims] 1. A film roll obtained by winding a heat-shrinkable polyester film, wherein the heat-shrinkable polyester film is wound in a constant region where the film properties are stable in the length direction of the film. The end on the starting side is the first end, the end on the winding end side is the second end, and the first sample cut-out portion is located within 2 m of the inside of the second end and the first end. When the final cutout portion is provided within 2 m of the inside and the sample cutout portion is provided about every 100 m from the first sample cutout portion, the following requirements (1) and (2) are satisfied. Shrinkable polyester film roll. (1) 10 cm cut out from each sample cutout part
95 for each square sample of × 10 cm
When immersed in warm water of ℃ for 10 seconds and pulled up, and then immersed in water of 25 ℃ for 10 seconds and pulled up, the heat shrinkage rate in the maximum shrinkage direction of all samples was 20% or more, and in the maximum shrinkage direction The heat shrinkage in the orthogonal direction is 7% or less (2) 10 cm cut out from each sample cutout part
When the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction was measured by the method described in (1) above for each square sample of × 10 cm, and the average heat shrinkage rate of these orthogonal direction heat shrinkage rates was calculated. The orthogonal heat shrinkage of all samples is
It is within ± 1.5% of the average heat shrinkage ratio 2. When the average heat shrinkage ratio of the heat shrinkage ratios in the maximum shrinkage direction measured by the method for each of the cut-out samples is calculated, the maximum heat shrinkage ratio in the maximum shrinkage direction is The heat-shrinkable polyester film roll according to claim 1, wherein the heat-shrinkable polyester film roll is within a range of ± 5% of the average heat shrinkage in the shrinking direction. 3. The heat-shrinkable polyester film roll according to claim 1, wherein the heat-shrinkable film is formed of a mixture of two or more polymers having different compositions. 4. The heat-shrinkable polyester film roll according to claim 1, wherein the heat-shrinkable polyester film has a width of 0.2 m or more and a length of 300 m or more. 5. A film-forming step of forming a film while mixing a polymer used in the largest amount and one or more other polymers having different compositions from this polymer and performing melt extrusion, and a film-forming step obtained by this film-forming step. The heat shrinkability imparting step of biaxially stretching the stretched film at different stretch ratios in directions substantially orthogonal to each other, and a rolling step of winding the resulting heat shrinkable film. A method for producing a heat-shrinkable polyester film roll, wherein the shape of a raw material chip of each polymer used is an elliptic cylinder having an elliptical cross section having a major axis and a minor axis, and a polymer other than the polymer used most The raw material chips of the above are the average major axis (mm), the average minor axis (mm), and the average chip length (m) of the raw material chips of the polymer used most.
m), each having an average major axis (mm), an average minor axis (mm) and an average chip length (mm), which are included within a range of ± 20%, respectively, and further when stretched in a direction having a smaller stretch ratio. A method for producing a heat-shrinkable polyester film roll, wherein the stretching temperature is set to "glass transition temperature of polyester film + 50 ° C" or more. 6. A stretching speed at the time of stretching in a direction having a small stretching ratio, wherein the stretching speed defined by the following formula is 20:
The method for producing a heat-shrinkable polyester film roll according to claim 5, wherein the heat-shrinkable polyester film roll is set in a range of up to 1,000 times / minute. Stretching speed = L ₁ / T ₁ [wherein, L ₁ is the stretching ratio, and T ₁ is the time (minutes) required to give the stretching ratio on the left] 7. Preheating is performed prior to stretching in a direction with a small stretching ratio, and the preheating temperature is set to a temperature 10 to 80 ° C. lower than the stretching temperature when stretching in a direction with a small stretching ratio. The method for producing a heat-shrinkable polyester film roll according to claim 5 or 6, which is set. 8. A method for producing a heat-shrinkable film roll, which comprises a step of melt-extruding a film using an extruder equipped with a funnel-shaped hopper as a raw material chip supply section, wherein the hopper has an inclination angle of 65 ° or more. The method for producing a heat-shrinkable polyester film roll according to any one of claims 5 to 7. 9. A fluctuation range of a surface temperature of a film measured at an arbitrary point in a main stretching step of stretching in a direction having a large stretching ratio, a preheating step prior to the main stretching step, and a heat treatment step subsequent to the main stretching step. Is within a range of an average temperature of ± 1 ° C. over the entire length of the film.
9. The method for producing a heat-shrinkable polyester film roll according to any one of 8 to 8.