JP2005138387A - Heat-shrinkable polyolefinic film roll and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-shrinkable polyolefinic film roll capable of reducing the occurrence of a defective product in providing a labelled container product by manufacturing a heat-shrinkable label/bag from a roll formed by winding the long heat-shrinkable polyolefinic film and covering a container with the heat-shrinkable label/bag to thermally shrink the label/bag, and its manufacturing method. <P>SOLUTION: In the heat-shrinkable polyolefinic film roll formed by winding the heat-shrinkable polyolefinic film, the heat-shrinkable polyolefinic film satisfies specific physical properties along with following requirement (1) wherein the heat shrinkage factor in the maximum heat-shrink direction of the heat-shrinkable polyolefinic film measured by immersing a square sample with a dimension of 10×10 cm, which is cut from the film by a sample cutting part provided at every 100 m, in hot water of 85°C for 10 sec to draw up the same and subsequently immersing the same in water for 10 sec at 25°C to draw up the same, is 20% or above with respect to all samples. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film roll obtained by winding a heat-shrinkable polyolefin film suitable for labeling use, and more specifically, a heat-shrinkable polyolefin having good outer surface slipperiness when used as a beverage bottle label. The present invention relates to a film roll formed by winding a film.

  Heat-shrinkable films are widely used for applications such as shrink wrapping, shrinkage labels, cap seals, etc. by utilizing the property of shrinking by heating. Among these, polyolefin films are used in various containers such as polyethylene terephthalate (PET) containers, polyethylene containers, and glass containers for the purposes of labels, cap seals, and integrated packaging.

In order to produce labels and the like, the following methods are usually employed. That is, the raw polymer is continuously melt extruded to produce an unstretched film. Next, stretching is performed to obtain a film roll. While feeding out the film from this film roll, it is slit to a desired width and wound into a roll again. Subsequently, character information such as various product names and designs are printed. After the printing is finished, the tube is manufactured by overlapping and joining the left and right ends of the film by means such as solvent bonding (tubing process). The slit process and the printing process may be reversed in order. If the obtained tube is cut into a suitable length, it becomes a cylindrical label, and a bag can be manufactured by joining one open end of this cylindrical label.
In addition, the inside of a shrink tunnel (steam tunnel) that covers the above-mentioned label or bag, etc., and heat-shrinks by blowing steam, or a shrink tunnel (hot-air tunnel) that heat-shrinks by blowing hot air, By passing it on a conveyor or the like, and thermally shrinking a label or bag, it is brought into close contact with the container to obtain a final product (labeled container).

By the way, in this heat shrinking process, when the fluctuation of the heat shrinkage rate of each label, bag, etc. is large, the heating conditions in the tunnel are the same, so there are labels, bags, etc. that do not show an appropriate heat shrinkage rate. May occur. As a result, defective appearance due to insufficient shrinkage, shrinkage spots, wrinkles, pattern distortion, vertical shrinkage, etc. results in a defective product and cannot be shipped to the market. Normally, labels, bags, etc. are processed from the same film roll from a single film roll, so if the heat shrinkage behavior of a film wound on a single film roll varies greatly, There has been a problem that the defective rate in the shrinking process increases.
Until now, there is one in which the thickness in the width direction of the film roll is adjusted (see Patent Document 1, etc.).
JP 2002-28972 A

  However, there is no disclosure of a technique for suppressing fluctuations in the heat shrinkage rate.

  In the present invention, a heat-shrinkable label, a bag, etc. are manufactured from a roll wound with a long film, and these are put on a container and thermally contracted to provide a labeled container product. It is an object of the present invention to provide a heat-shrinkable polyolefin film roll that can solve a number of problems in the process and reduce the occurrence of defective products, and a method for producing the same.

  The inventor is a film roll formed by winding a heat-shrinkable polyolefin film, and the heat-shrinkable polyolefin film has at least one of the following requirements (2) to (5) together with the following requirement (1). It has a gist where either one is satisfied.

(1) When the winding start end of the film in the steady region where the film properties are stable in the length direction of the film is the first end, and the end on the winding end is the second end, The first sample cutout portion is provided within 2 m inside the two end portions, and the final cutout portion is provided within 2 m inside the first end portion, and the sample cutout portion is provided approximately every 100 m from the first sample cutout portion. Each sample cut into a square shape of 10 cm × 10 cm was dipped in hot water at 85 ° C. for 10 seconds, then dipped in water at 25 ° C. for 10 seconds, and then heat shrinkage in the maximum heat shrink direction. The rate is 20% or more for all samples.

(2) For each sample appropriately cut out from each sample cutout section described in (1) above, when the average value of the heat shrinkage rate in the maximum shrinkage direction described in (1) was calculated, the heat of all the samples The shrinkage rate is within a range of ± 5% of this average value.

(3) When the average value is calculated by measuring the heat shrinkage stress in the maximum shrinkage direction for each sample cut out from each sample cutout portion described in requirement (1) of claim 1, the maximum of all the samples The heat shrinkage stress in the shrinkage direction is 3.0 MPa or more, and when the average value of these maximum heat shrinkage stresses is calculated, the maximum heat shrinkage stress of all the samples falls within this average value ± 1.0 MPa. ing.

(4) Each sample cut out to 10 cm × 10 cm from each sample cut out appropriately from each sample cut-out part described in requirement (1) of claim 1 is immersed in warm water at 85 ° C. for 10 seconds. When the sample is pulled up and then dipped in water at 25 ° C. for 10 seconds, the thermal shrinkage rate in the direction perpendicular to the maximum shrinkage direction of all the samples is within 7%, and the average value of the thermal shrinkage rates in these orthogonal directions Is calculated, the thermal contraction rate in the orthogonal direction of all the samples is within ± 2% of the average value.

(5) A film in a steady region where the film physical properties are stable in the length direction of the film is appropriately slit in the length direction, and both sides of the slit film are overlapped with each other to form a tube by solvent bonding with tetrahydrofuran, With respect to the tube roll obtained by winding in the flat crushed state, the first sample cutout portion is provided within 2 m inside the end of the tube winding, and the final cutout portion is provided within 2 m inside the tube winding start. At the same time, a sample cut-out portion is provided about every 100 m from the first sample cut-out portion, and the tube-like sample obtained from each sample cut-out portion is cut into a film-like test piece having a width of 15 mm. Set the distance on the tensile tester set at 50 mm so that the solvent adhesion part is located in the center of the chucks. When the solvent adhesion strength was measured by performing a tensile test under the conditions of 23 ° C. and a pulling speed of 200 m / min, the solvent adhesion strength of all the samples was 1 N / 15 mm width or more, and when these average values were calculated, The solvent adhesive strength of all the samples is within the range of ± 2 N / 15 mm width of this average value.

  The heat-shrinkable polyolefin film roll of the present invention in which a film satisfying at least one of the requirements (2) to (5) is wound together with the above requirement (1) Since the fluctuation of surface characteristics such as slip and antistatic property is extremely small, it is possible to reduce the occurrence of defects due to variations in individual surface characteristics when labels and bags are manufactured from this film roll, resulting in extremely poor product defects. Can be reduced.

  Moreover, it is preferable that the heat-shrinkable polyester film having a width of 0.2 m or more and a length of 300 m or more is wound on the film roll of the present invention. This is because the film having the above width and length is likely to change the surface characteristics of the film unless the present invention is applied, and it is meaningful to apply the present invention. In addition, it has excellent processing suitability and handling suitability in the printing process and the processing process up to the final product.

The production method of the present invention is a method for producing a heat-shrinkable polyolefin film comprising a step of mixing and extruding a polymer having the largest amount of use with one or more other polymers having different compositions from the polymer. And
The shape of each polymer raw material chip to be used is an elliptical shape having an elliptical cross section having a major axis and a minor axis, and raw material chips other than the most used polymer are replaced by the average major axis of the most used polymer raw material chip ( mm), average minor axis (mm), and average chip length (mm), average major axis (mm), average minor axis (mm), and average chip length (mm) included in a range within ± 20%, respectively. It has a gist. It is effective for suppressing fluctuations in film composition.
The production method of the present invention is a method for producing a heat-shrinkable polyolefin film roll including a step of melt-extruding a film using an extruder equipped with a raw material chip supply unit and a funnel-shaped hopper, and the inclined as the hopper It is preferable to use a hopper having an angle of 65 ° or more. It is effective in suppressing composition fluctuations in the film.

  Yet another production method of the present invention is a method for producing a heat-shrinkable polyester film roll including a step of melt-extruding a film using an extruder equipped with a funnel-shaped hopper as a raw material chip supply unit, The gist is that a hopper having a capacity of 15 to 120% by mass of the discharge amount per hour of the extruder is used. It is effective for suppressing fluctuations in the film composition.

  Still another production method of the present invention is a method for producing a heat-shrinkable film roll by drawing a film obtained by melt-extrusion of a raw material polymer and then winding the film once or after cooling. The fluctuation range of the surface temperature of the film measured at an arbitrary point in each of the preheating step, the stretching step, and the heat treatment step after stretching is controlled within the range of the average temperature ± 1 ° C. over the entire length of the film. Has a gist. It is effective for suppressing fluctuations in heat shrinkage behavior.

  The heat-shrinkable polyolefin film roll of the present invention has little compositional and physical property fluctuations of a long film wound around the film roll, defects in the solvent bonding process, insufficient shrinkage in the heat shrinking process, shrinkage spots The occurrence of defects due to the occurrence of wrinkles, distortion, vertical shrinkage, etc. is extremely small. In addition, the method for producing a heat-shrinkable polyolefin roll of the present invention can easily reduce the fluctuation of the polymer composition and the fluctuation of the heat-shrinking behavior of the long film, and is very useful for industrial production.

As a result of studying various problems that occur in the process of manufacturing labels and bags from the heat-shrinkable polyolefin film and the heat-shrink process, the present inventors have found that these defects are caused when the raw polymer of the film is a homopolymer. In addition, the present inventors have found that this is likely to occur in the case of a polymer containing a secondary constituent unit other than the main constituent unit obtained by copolymerization or blending. That is, it was considered that the composition variation of the polymer occurred in the long film, and this was one factor of the variation of the heat shrinkage behavior. And if it was the heat-shrinkable polyolefin film roll which concerns on this invention, since the fluctuation | variation of a composition fluctuation | variation and a heat shrink behavior was small, it discovered that said malfunction was not raise | generated. Hereinafter, the present invention will be described in detail.
The object of the present invention is a polyolefin-based heat-shrinkable film roll. In a wide temperature range from low temperature to high temperature, it has excellent shrink finish, can give a shrink-finished appearance with little shrinkage spots, wrinkles and distortion, and can have a beautiful gloss and transparency.

The film wound around the heat-shrinkable polyester film roll of the present invention must satisfy the following requirement (1).
(1) When the winding start end of the film in the steady region where the film properties are stable in the length direction of the film is the first end, and the end on the winding end is the second end, The first sample cutout portion is provided within 2 m inside the two end portions, and the final cutout portion is provided within 2 m inside the first end portion, and the sample cutout portion is provided approximately every 100 m from the first sample cutout portion. Each sample cut into a square shape of 10 cm × 10 cm was dipped in hot water at 85 ° C. for 10 seconds, then dipped in water at 25 ° C. for 10 seconds, and then heat shrinkage in the maximum heat shrink direction. The rate is 20% or more for all samples.

First, the meaning of the above-mentioned (1) “steady region where film physical properties are stable in the length direction of the film” will be described. The “steady region where the film physical properties are stable in the length direction of the film” is a region where the film forming process and the stretching process are stably performed during film production, and the film physical properties are almost 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, the amount of the most secondary component units and other characteristics are more uniform than the conventional level. The technical idea is to make it. In actual operation, the film composition is not required to be uniform even when the film composition is obtained when the raw material supply method and film forming conditions are unstable. For this reason, it is assumed that the sampling for evaluating the characteristics requiring homogenization is performed only in the region where the film forming process and the stretching process are operated in a stable steady state, that is, the “steady region”.
Therefore, for example, if the film is about 10 m from the beginning of winding of the roll when the steady operation is not performed, sampling is not performed from this portion, and the 10 m from the beginning of winding is sampled as the first end of the film.
The number of the steady regions (steady operation regions) is normally one place per film roll (one place over the entire film roll). However, since there may be a plurality of locations depending on the manufacturing situation, sampling is performed only from the steady region in this case. The steady region can be evaluated, for example, by measuring the thermal shrinkage rate in the maximum shrinkage direction of the film by a method described later. That is, the region where the heat shrinkage rate is within about 20% (the difference between the maximum value and the minimum value of the heat shrinkage rate of a plurality of samples is within about 20%) may be regarded as the steady region.

  Next, a sampling method will be described. About 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 second end By providing a first cutout portion within 2 m from the inside, a final cutout portion within 2 m from the first end portion, and providing a sample cutout portion about every 100 m from the first cutout portion Samples are selected at approximately equal intervals over the entire length of the steady region of the film. Note that “about every 100 m” means that the sample may be cut out at about 100 m ± 1 m.

The sampling method will be described in more detail. For example, when a heat-shrinkable film having a total length of a steady region and a length of 498 m is wound around a roll, the first sample (1) is formed within 2 m from the end of film winding (second end). ). The area to be cut out is appropriately selected according to the physical property value to be measured. Subsequently, the second sample [2] is cut out at a distance of about 100 m from where the first sample [1] was cut out. Similarly, the third sample [3] is cut out at about 200 m, the fourth sample [4] is cut out at about 300 m, and the fifth sample [5] is cut out at about 400 m. Here, since the remainder is shorter than 100 m, the sixth (final) sample [6] cuts out any portion within 2 m from the start of winding of the film (first end).
The requirement (1) of the present invention is that the heat shrinkage rate in the maximum shrinkage direction of all the samples thus cut is 20% or more. If the heat shrinkage rate of the heat-shrinkable polyester film is less than 20%, the heat shrinkage force of the film is insufficient, and when the container is coated and shrunk, it does not adhere to the container, resulting in poor appearance. It is not preferable. A more preferable heat shrinkage rate is 40% or more, and further preferably 60% or more.
Here, the heat shrinkage rate in the maximum shrinkage direction means the heat shrinkage rate in the direction in which the sample is most contracted, and the maximum shrinkage direction is the length in the longitudinal direction or the transverse direction of the cut-out square sample. It is decided. Further, the heat shrinkage rate (%) was 25 ° C. ± 0.5 after a sample of 10 cm × 10 cm was immersed in warm water at 85 ° C. ± 0.5 ° C. for 10 seconds under a no-load condition and then heat shrunk. The film was measured in accordance with the following formula after measuring the length in the longitudinal and lateral directions after being immersed in water at 10 ° C. for 10 seconds under no load condition (hereinafter, the heat shrinkage in the maximum shrinkage direction measured under these conditions). The rate is simply abbreviated as “heat shrinkage rate”).
Heat shrinkage rate = 100 × (length before shrinkage−length after shrinkage) ÷ length before shrinkage

In requirement (2) of the present invention, when the average value of the heat shrinkage rate in the maximum shrinkage direction described in requirement (1) is calculated, the heat shrinkage rates of all the samples are within ± 5% of this average value. It is in the range.
As described in the requirement (1), the long film employed in the present invention has a heat shrinkage rate of 20% or more in the maximum shrinkage direction. Since the film having a value within ± 5% has a uniform heat shrinkage rate over the entire length of the film, fluctuations in the heat shrinkage rate of one piece, one label, a bag, etc. are reduced, so that the coating shrinks. Defects in the process can be reduced, and the defect rate of products can be drastically reduced. The variation degree of the heat shrinkage rate is more preferably within ± 3% of the average value of the heat shrinkage rate, and more preferably within ± 2%.

Requirement (3) is the maximum heat shrinkage stress value in the maximum shrinkage direction for each sample appropriately cut out from each sample cutout section described in requirement (1), in hot air at a temperature of 90 ° C. and a blowing speed of 5 m / sec. When measured under the conditions of a sample of 20 mm and a distance between chucks of 100 mm, the maximum heat shrinkage stress value of all the samples is 3.0 MPa or more, and when the average value of these maximum heat shrinkage stress values is calculated, When the maximum heat shrinkage stress values of the samples calculate this average value, the maximum heat shrinkage stress values of all the samples are within the range of ± 1.0 MPa of this average value.
Here, the maximum heat shrinkage stress value is specifically measured as follows.
(1) A sample having a length in the maximum shrinkage direction of 200 mm and a width of 20 mm is prepared.
(2) The inside of the heating furnace of a tensile tester (for example, “Tensilon” manufactured by Toyo Seiki Co., Ltd.) equipped with a hot air type heating furnace is heated to 90 ° C.
(3) Stop air flow and set the sample in the heating furnace. The distance between chucks is 100 mm (constant).
(4) The heating furnace door is quickly closed, air blowing (90 ° C., blowing speed 5 m / sec) is resumed, and heat shrinkage stress is detected and measured.
(5) The maximum value is read from the chart, and this is taken as the maximum heat shrinkage stress value (MPa).
If the maximum heat shrinkage stress value of the film is less than 3.0 MPa, an appearance defect due to insufficient shrinkage stress of the film occurs, and a problem of deterioration in tear resistance occurs due to insufficient mechanical strength. A more preferred lower limit of the maximum heat shrinkage stress value is 3.5 MPa, and a more preferred lower limit is 4.0 MPa. Moreover, an average value is calculated from the maximum heat shrinkage stress value measured as described above, and a change in the maximum heat shrinkage stress value of the long film is obtained. When the fluctuation range of the maximum heat shrinkage stress value is within an average of ± 0.5 MPa or more and within ± 1.0 MPa, the defect rate can be reduced by adjustment in the coating shrinkage step. Further, when the fluctuation of the maximum heat shrinkage stress value is less than the average value ± 0.5 MPa, the process adjustment is not required, and a label, a bag and the like having a very excellent shrinkage finish can be obtained. The variation in the maximum heat shrinkage stress value is more preferably within a range within ± 0.4 MPa of the average value of the maximum heat shrinkage stress value. In addition, the average value itself of the maximum heat shrinkage stress value is preferably 4.0 MPa or more. A more preferred lower limit is 4.5 MPa, and a still more preferred lower limit is 5.0 MPa.

  Requirement (4) is that each sample cut out to 10 cm × 10 cm from each sample cutting part described in requirement (1) is dipped in hot water at 85 ° C. for 10 seconds and then pulled up into water at 25 ° C. When the sample is immersed for a second and pulled up, the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction of all the samples is 7% or less, and when the average value of the heat shrinkage rates in these orthogonal directions is calculated, all the samples The thermal contraction rate in the orthogonal direction is within the range of ± 2% of this average value. This requirement (8) is particularly a requirement for a film that does not cause an appearance defect called “vertical sink”.

Here, vertical shrinkage means that the length of the label after shrinkage is uneven, so that the upper edge of the label after covering and shrinking a PET bottle or the like draws a curved line downward, or the lower edge is curved upward An appearance defect that draws a line.
When the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction (orthogonal direction heat shrinkage rate) exceeds 7%, appearance defects due to vertical shrinkage tend to occur. More preferably, the heat shrinkage rate in the orthogonal direction is 6% or less, more preferably 5% or less.

  Moreover, by keeping the fluctuation of the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction of one heat shrinkable film roll within a range of ± 2% of the average value of the heat shrinkage rate in the orthogonal direction, one piece, one piece Since the thermal shrinkage fluctuations of the labels, bags, etc. are reduced, appearance defects due to variations in vertical shrinkage in the coating shrinkage process can be reduced, and the defective rate of products can be drastically reduced. The variation degree of the orthogonal direction heat shrinkage rate is more preferably within ± 1.8% of the average heat shrinkage rate, further preferably within ± 1.5%, and most preferably within ± 1%.

  In addition to the requirement (1), the long film satisfying any of the requirements (2) to (4) has a small variation in the heat shrinkage behavior of the film. The frequency of occurrence of defects such as wrinkles, distortion, and vertical shrinkage becomes very small. It is more preferable that the film satisfies the requirement (2) or (3) and the requirement (4) together with the requirement (1), and more preferably a film satisfying any of the requirements (2) to (4). .

  In the requirement (5) of the present invention, attention is paid to the solvent adhesive strength as one of the film physical properties indicating that the composition of the film in the steady region is uniform, and the fluctuation is defined. That is, the requirement (5) of the present invention is that, in a steady region where the physical properties are stable in the length direction of the film, the film is slit in the length direction and a solvent is bonded with tetrahydrofuran to form a tube, which is flattened. About the tube roll obtained by winding in the crushed state, the first sample cutout portion is provided within 2 m from the end of the tube winding, and the final sample cutout portion is provided within 2 m from the beginning of the tube winding. Sample cut-out portions are provided at intervals of about 100 m from the sample cut-out portion, and the tube-like sample obtained from each sample cut-out portion is cut open to form a film-like test piece having a width of 15 mm, and the distance between chucks is set to 50 mm. Set the tensile tester so that the solvent adhesion part is located in the center of the chucks, and set the temperature at 23 ° C and the tensile speed. When the tensile strength test was conducted under the condition of 200 mm / min and the solvent adhesive strength was measured, the solvent adhesive strength of all samples was 1 N / 15 mm width or more, and when the average value was calculated, The adhesive strength is within the range of ± 2 N / 15 mm width of this average value.

  The adjustment method of the test piece for solvent adhesive strength measurement in the above requirement (5) is as follows. First, the heat-shrinkable film roll before shrinkage is stored in an environment controlled at a temperature of 30 ° C. ± 1 ° C. and a relative humidity of 85 ± 2%. After 250 hours, it was taken out, and using a tube forming device, tetrahydrofuran was applied in a width of 2 ± 1 mm slightly from the edge of one surface of one end of the film (coating amount 3.0 ± 0.3 g / mm 2). ) Immediately roll the film and overlap the edges to bond and process it into a tube. The tube is wound in a flat state and rolled. A first sample cutout is provided within 2 m from the end of winding of the tube in the tube roll, and a final cutout is provided within 2 m from the beginning of winding of the tube, and a sample is cut out every about 100 m from the first sample cutout. Provide a part. In addition, the thermal shrinkage rate in the maximum shrinkage direction of the film is measured in the vicinity of each sample cutout portion, and it is confirmed whether or not the film physical property is a steady region. The cut-out size for the solvent adhesion test is not particularly limited, but the length direction of the tube corresponds to the width direction of the test piece to be described later, and the test piece needs to have a width of 15 mm, so about 10 test pieces can be collected. Thus, it is preferable to cut out 150 mm or more in the length direction of the tube. Each tube-shaped sample cut out in this way is cut open at a place other than the solvent adhesion portion, and a film-like test piece having a length of about 100 mm and a width of 15 mm is prepared. This is a test piece for measuring the solvent adhesive strength. About 10 test pieces are desirably prepared for each sample cut-out portion.

  The solvent adhesion strength is set in a tensile tester so that the solvent adhesion part is located at the approximate center between chucks, and a tensile test is performed under the conditions of a temperature of 23 ° C., a pulling speed of 200 mm / min, and a distance between chucks of 50 mm. taking measurement. The average value of the solvent adhesive strength for each sample cut-out portion was obtained (or the average value if 10 test pieces were prepared and the solvent adhesive strength was measured), and this was obtained for each sample cut-out portion. The solvent adhesive strength of Moreover, the average value of the solvent adhesive strength of all measured test pieces is also calculated.

  In order to satisfy the requirement (5), the solvent adhesive strength of all samples must be 1 N / 15 mm width or more. If the solvent adhesive strength is less than 1 N / 15 mm width, a defect that the adhesive part peels off after forming a label, bag or the like occurs. A more preferable lower limit of the solvent adhesive strength is 1.5 N / 15 mm width or more. On the other hand, if the solvent adhesion is too good, the solvent adhesion portion may lose its flatness due to swelling of the film due to the penetration of the solvent, and the appearance may be deteriorated. Is 8.0 N / 15 mm width or less, preferably 7.0 N / 15 mm width or less. The unit of the solvent adhesive strength is “N / 15 mm width” because the width of the test piece is 15 mm.

Further, in order to satisfy the requirement (5), the solvent adhesive strength of all the samples must be within the range of ± 2 N / 15 mm width of this average value. In a film in which the solvent adhesive strength of each sample is not within the average value ± 2 N / 15 mm width, a location where the solvent adhesive strength is insufficient and a location where the solvent adhesive strength is too large are mixed. Therefore, a tube obtained by solvent-bonding from such a film has an adhesive portion that is easily peeled off at a location where the solvent adhesive strength is insufficient, and at a location where the solvent adhesive strength is too high, The flatness of the film is lost, resulting in poor appearance, which is not preferable. The solvent adhesive strength of each sample is preferably within an average value ± 1.8 N / 15 mm width, and more preferably within an average value ± 1.6 N / 15 mm width.
The average value of the solvent adhesive strength of each sample is preferably 2.5 N / 15 mm width or more. More preferably, it is 3 N / 15 mm width or more, and still more preferably 3.5 N / 15 mm width or more.
The average value of the solvent adhesive strength of the long film is preferably 2.5 N / 15 mm width or more. More preferably, it is 3 N / 15 mm width or more, and still more preferably 3.5 N / 15 mm width or more.

By suppressing fluctuations in the solvent adhesive strength of the long film within the above range, products and appearances with insufficient solvent adhesive strength in labels and bags manufactured from tubes obtained by solvent bonding of this film The incidence of defective products can be drastically reduced.
1,3-dioxolane was used as the solvent for bonding when determining the solvent bonding strength, but other solvents may be used when actually manufacturing the tube. Specifically, aromatic hydrocarbons such as benzene, toluene, xylene and trimethylbenzene; halogenated hydrocarbons such as methylene chloride and chloroform; phenols such as phenol; furans such as tetrahydrofuran; and mixed solvents thereof Can be mentioned.

  If the long film currently wound by the film roll of this invention demonstrated above satisfy | fills any one of requirements (2)-(5) with the said requirement (1), it is a film roll of this invention. is there. Those satisfying two or more of requirements (2) to (5) together with requirement (1) are preferred, and films satisfying all of requirements (1) to (5) are more preferred.

  Next, the preferable manufacturing method of the elongate film which shows a uniform composition, a heat shrink characteristic, and a surface characteristic over the full length is demonstrated.

  The heat-shrinkable polyolefin film is made by blending two or more kinds of polymers with different types and compositions, or by using multiple copolymerization monomer components, etc., from the viewpoint of achieving both heat shrink properties, natural shrinkage, and strength. In addition to the main constituent unit, a secondary constituent unit is introduced into the raw polymer to change the properties of the resulting film.

For example, the homopolymer includes polyethylene, polypropylene, polybutylene, polybutene-1, and the like. Examples of the copolymer include random copolymers such as ethylene-α-olefin random copolymers, propylene-α-olefin random copolymers, butylene-α-olefin random copolymers, and propylene-ethylene block copolymers. And a block copolymer such as polypropylene elastomer. Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms, and ethylene, propylene, butene-1, hexene-1, octene-1, and the like are preferably used. An ethylene-propylene random copolymer, propylene It is particularly preferable to use a -butene random copolymer, an ethylene-propylene-butene random copolymer, or the like. Further, there is no particular limitation on the three-dimensional structure of these polymers, and isotactic, atactic, syndiotactic or a mixed structure thereof may be used.
By introducing a copolymer component, an olefin polymer having high crystallinity can be made amorphous and a high heat shrinkage rate necessary for a heat shrinkable film can be imparted.

  Furthermore, other components include cyclic olefin resins, petroleum resins, and styrene resins.

The cyclic olefin-based resin is a general generic name. Specifically, 1) a polymer obtained by hydrogenating a ring-opened (co) polymer of a cyclic olefin as necessary, and 2) an addition (co) weight of a cyclic olefin. 3) A random copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene. Other examples include 4) graft modified products obtained by modifying the above 1) to 3) into unsaturated carboxylic acids or derivatives thereof. The cyclic olefin is not particularly limited. For example, bicyclohept-2-ene (2-norbornene) and derivatives thereof such as norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-butylnorbornene, Examples thereof include 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethylnorbornene, 5-phenylnorbornene, and 5-benzylnorbornene. Examples of tetracyclo-3-dodecene and derivatives thereof include 8-methyltetracyclo-3-dodecene, 8-ethyltetracyclo-3-dodecene, and 5,10-dimethyltetracyclo-3-dodecene. it can.
Cyclic olefin resins have a higher glass transition temperature than other polyolefins, and as a result, the effect of improving the rigidity of the film compared to other polyolefin films and the disadvantages of polyolefin films in general are natural. Has the effect of reducing shrinkage. In particular, the higher the glass transition temperature among the cyclic polyolefins, the greater the above-mentioned effect.
The glass transition temperature of the cyclic polyolefin is preferably 70 ° C. or higher and 140 ° C. or lower, more preferably 90 ° C. or higher and 110 ° C. or lower. By setting the glass transition temperature to 90 ° C. or higher, the amount of cyclic polyolefin added can be reduced, and therefore the cost of the film raw material can be reduced. On the other hand, when the glass transition temperature is 140 ° C. or higher, stretchability during film formation deteriorates, thickness unevenness tends to occur, and appearance tends to deteriorate.

  In addition, the petroleum-based resin used in the present invention is a polymerizable substance in a specific fraction (containing a polymerizable compound such as olefin and diolefin) obtained in the process of petroleum refining industry and petrochemical industry, In particular, it refers to a polymerized resin as it is without isolation and purification. More specifically, among the above-mentioned aromatic hydrocarbon resins and aromatic petroleum resins are alicyclic saturated hydrocarbon resins obtained by partial hydrogenation or complete hydrogenation, Examples include commercially available products such as Alcon manufactured by Arakawa Chemical Industries, Ltd. or Escoretz manufactured by Toenex Corporation. By using a petroleum resin, it is possible to secure a shrinkage ratio required for a heat-shrinkable film by making the polymer non-crystalline, and it is also possible to improve stretchability during film formation. The softening point of the petroleum resin is preferably 110 ° C. or higher, and a more preferable softening point is 125 ° C. or higher. More preferably, it is 140 ° C. or higher. This is because the higher the softening temperature of the petroleum resin, the higher the heat shrinkage rate can be obtained. Further, when the softening point of the petroleum resin is less than 110 ° C., there are cases where the film becomes sticky and causes problems in post-processing such as printing, or becomes cloudy due to changes over time.

  A styrene resin is a copolymer of a styrene monomer and a conjugated diene monomer, and can provide solvent adhesion when processing a film into a tube shape. High heat shrinkability can be obtained because it is a conductive polymer.

Examples of the styrene monomer include styrene, α-methylstyrene, and p-methylstyrene. Examples of the conjugated diene monomer include butadiene, isoprene, 1,3-butadiene and the like, and one or more of these conjugated diene monomers are included.
Block copolymers of these conjugated diene monomers and the above styrene monomers are listed as styrene polymers used in the present invention. Among these, the block copolymer most preferably used is a styrene-butadiene block copolymer in which the styrene monomer is styrene and the conjugated diene monomer is butadiene. In the block copolymer, the styrene content in the polymer is preferably 15 to 90% by weight, more preferably 20 to 85% by weight. If the styrene content exceeds 95% by weight, the impact resistance of the film is lowered, which is not preferable. Further, when the styrene content is 10% by weight or less, the solvent adhesiveness is lowered, and the function may be impaired when the outer layer is used as the solvent adhesive layer. In addition, the diene monomer is soft, and when this ratio increases, sufficient rigidity cannot be obtained, and the natural shrinkage in the direction perpendicular to the main shrinkage direction of the film increases. As a result, the film roll is tightened in the radial direction, and troubles such as blocking may occur.

  In addition to the above resin components, terpene resins, rosin resins, coumarone-indene resins, and the like can be used.

  At this time, as a means for containing a plurality of types of polymers in the film, there are a method of performing copolymerization and using this copolymer polymer alone, and a method of blending different types of polymers. A method of blending different types of polymers is common.

  Variations in the composition of the polymer components that make up the film are particularly noticeable when the film is manufactured by blending two or more raw material chips with different polymer compositions, then melt-kneading and extruding from an extruder. To do. In industrial production, when using this production method, two or more kinds of polymer chips as raw materials are collected and supplied continuously or intermittently to a hopper or the like, and finally, immediately before or immediately above the extruder through a plurality of hoppers. Generally, a method of supplying quantitatively from a reservoir hopper or the like according to the extrusion amount of the extruder. However, depending on the capacity or shape of these hoppers and the like, when the remaining amount of the raw material polymer in the hopper changes, the mixing ratio of multiple types of raw material polymers supplied from the hopper changes, which causes a raw material segregation phenomenon. The composition of the polymer extruded from the extruder also fluctuates accordingly, causing fluctuations in the heat shrink behavior of the heat shrinkable film produced.

(Means 1)
In the present invention, as a means for reducing the composition variation of the polymer constituting the film due to the above cause, it is preferable to suppress the phenomenon of raw material segregation in the hopper by combining the shapes of plural types of polymer chips to be used. For example, a chip which is taken out from the polymerization apparatus in a melted state after polymerization and immediately cooled with water and then cut with a strand cutter has a cylindrical shape with an elliptical bottom surface. It is preferable to use different kinds of raw material chips whose average sizes of the diameter and the cylindrical height are within the range of the chip size of the raw material species having the highest use ratio within ± 15%, and the size is within ± 10%. It is more preferable to be within the range.

(Means 2)
Furthermore, in the present invention, it is preferable to reduce the ratio of fine powder generated by scraping of the raw material chips used as a means for reducing the composition fluctuation of the polymer constituting the film due to the above-mentioned causes. Since the fine powder promotes the generation of raw material segregation, it is preferable to reduce the ratio of the fine powder contained by removing the fine powder generated in the process. The ratio of the fine powder contained is preferably controlled within 1 wt%, more preferably within 0.5 wt% throughout the entire process until the raw material chips enter the extruder.

Furthermore, in the present invention, it is preferable to optimize the capacity and shape of the hopper to be used as a means for reducing raw material segregation in the hopper.
(Means 3)
The proper capacity of the hopper to be used is the hopper capacity in the process from mixing two or more kinds of raw materials to supplying the raw material to the extruder (discharge amount per hour of the extruder) × It is preferable to be within the range of 0.05 to (discharge amount per hour of the extruder) × 1.2, and (discharge amount per hour of the extruder) × 0.1 to (1 of the extruder) It is more preferable that the discharge amount per time is within a range of up to 1.0.
(Means 4)
As an appropriate shape of the hopper, it is preferable to use a shape in which the angle of the bottom of the hopper is designed so as to become a mass flow or a state close thereto when discharging the raw material in the hopper. Taking the above-mentioned polyester raw material chip as an example, the angle of the hopper bottom is preferably 70 degrees or more, and more preferably 75 degrees or more.
As a method of mixing a plurality of types of raw materials, a method of mixing while continuously feeding each raw material in a constant amount with a hopper directly above the extruder is most preferable, but the plurality of types of raw material chip sizes were controlled within the aforementioned range. After mixing the materials, they can be led to an extruder through a plurality of intermediate hoppers. When mixing multiple types of raw materials, use a method of mixing multiple types of raw materials in a hopper quantitatively from an apparatus that continuously supplies quantitative raw material chips, or mixing in advance using a blender, etc. In the latter case, it is preferable to pay attention to the equipment, the raw material chip size and the like so that the raw material segregation does not occur during discharge after mixing.

  In the heat-shrinkable polyolefin film of the present invention, an organic lubricant component, inorganic particles, organic salt particles and crosslinked polymer particles can be added as a lubricant.

  As organic lubricant components, paraffin wax, micro wax, polypropylene wax, polyethylene wax, ethylene acrylic wax, stearic acid, behenic acid, 12-hydroxystearic acid, stearic acid amide, oleic acid amide, erucic acid amide, behemic acid amide , Methylene bis stearamide, ethylene bis stearamide, ethylene bis oleate, butyl stearate, monoglyceride stearate, pentaerythritol tetrastearate, hydrogenated castor oil, stearyl stearate, siloxane, higher alcohol polymer, stearyl It is preferable to add at least one kind of alcohol, calcium stearate, zinc stearate, magnesium stearate, lead stearate, etc. There.

Inorganic particles include calcium carbonate, kaolin, talc, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, riotium fluoride, etc. Is mentioned.
In particular, in order to obtain a film having a lower haze while obtaining good handling properties, the inorganic particles are preferably aggregated silica particles formed by agglomerating primary particles.
Examples of the organic salt particles include terephthalate such as calcium oxalate, calcium, barium, zinc, manganese, and magnesium.

  Examples of the crosslinked polymer particles include homopolymers or copolymers of vinyl monomers such as divinylbenzene, styrene, acrylic acid or methacrylic acid. In addition, organic particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting urea resin, and thermosetting phenol resin may be used.

  Examples of the method of adding the lubricant include a method of dispersing the lubricant and a lubricant in a polymer polymerization step used as a film raw material, a method of adding the polymerized polyester again after melting. In order to disperse the lubricant and lubricant uniformly in the film roll, after the lubricant or lubricant is dispersed in the polymer by any of the methods described above, the shape of the polymer chip in which the lubricant or lubricant is dispersed is used. It is preferable to suppress the phenomenon of raw material segregation in the hopper. For example, the polymer chip that is taken out from the polymerization apparatus in a molten state after polymerization and immediately cooled with water and then cut with a strand cutter has a cylindrical shape with an elliptical bottom surface, but the major axis of the elliptical bottom surface, It is preferable to use different kinds of raw material chips in which the average size of the minor axis and the height of the cylindrical shape is within the range of the chip size of the raw material species having the highest usage ratio within ± 20%, and the size is ± 15%. It is more preferable to be within the range.

  Moreover, antioxidants, ultraviolet absorbers, antistatic agents, colorants, antibacterial agents, and the like can be added as necessary.

  If necessary, the polymer chip used in the present invention is dried using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer, and extruded into a film at a temperature of 180 to 270 ° C. At this time, it is preferable to take measures to reduce the composition fluctuation of the polymer component described above. For extrusion, the T-die method is preferred. After extrusion, it is cooled rapidly to obtain an unstretched film. Stretching is performed on the unstretched film, but in order to achieve the object of the present invention, the lateral direction is practical as the main shrinking direction. For example, when the main shrinkage direction is the longitudinal direction, the film can be formed in accordance with a normal operation in addition to changing the stretching direction in the following method by 90 degrees.

(Means 5)
Factors causing fluctuations in the heat shrinkage behavior of the long film include process fluctuations when the film is stretched, in addition to the composition fluctuations of the polymer components constituting the film. That is, in order to reduce the heat shrinkage fluctuation of the long film, it is preferable to suppress the fluctuation of the temperature in the step of stretching the film and reduce the fluctuation range of the surface temperature of the film as much as possible.
When uniaxially stretching in the transverse direction using a tenter, there are a preheating process before stretching, a stretching process, a heat treatment process after stretching, a relaxation process, a restretching process, and the like. In particular, in the preheating step, the stretching step, and the heat treatment step after stretching, controlling the fluctuation range of the surface temperature of the film measured at an arbitrary point within an average temperature of ± 1 degree is a uniform heat shrinkage behavior. Is a preferred means for. More preferably, the average temperature is within ± 0.5 ° C.
Temperature fluctuations in the preheating step and the stretching step greatly affect the fluctuations in the heat shrinkage rate (maximum shrinkage direction and orthogonal direction) and the maximum heat shrinkage stress value. Therefore, when the fluctuation range of the surface temperature of the film in these steps is small, the film is stretched or heat-treated at the same temperature over the entire length of the film, and the heat shrinkage behavior becomes uniform. Of course, it is preferable that the fluctuation range of the surface temperature of the film is small also in the relaxation treatment and the re-stretching treatment step.
In order to reduce fluctuations in the film surface temperature, for example, a wind speed fluctuation suppression facility equipped with an inverter so that the wind speed of the hot air that heats the film can be controlled, or a low pressure steam of 500 kPa or less (5 kgf / cm ² or less) as the heat source. It is good to use the equipment etc. which can suppress the temperature fluctuation of hot air.

  The fluctuation range of the surface temperature of the film measured at an arbitrary point is, for example, the film temperature fluctuation continuously during film production when, for example, 2 m has passed since the drawing process, for example, an infrared non-contact surface thermometer This is the range of fluctuation when measured by. Since the average temperature can be calculated when film production for one roll is completed, if the fluctuation range of the film surface temperature is within the average temperature ± 1 ° C, the film is stretched under the same conditions over the entire length of the steady region of the film. Therefore, the fluctuation of the heat shrinkage behavior is also reduced. If the composition of the long film is only made uniform, any one of the above means 1 to 4 may be adopted. It is more preferable to use two or more of the four means in combination, and it is more preferable to employ all of 1-4. Therefore, each raw material chip is reduced using a hopper that reduces the fine powder by means 4, uses the chip size defined in means 1, and has an inclination angle of means 2 of 65 ° or more and a capacity satisfying means 3. After mixing, it is preferable to form a film while continuously supplying a fixed amount to the extruder and controlling the discharge amount. In addition, the raw material chips may be mixed in advance and then supplied to the final hopper and the extruder via some intermediate (buffer) hoppers. When mixing multiple types of raw material chips, there is a method of mixing in a hopper using an apparatus that can continuously supply raw material chips, or a method of mixing in advance using a blender, etc. In the latter case, it is preferable to pay attention to the raw material chip size so that raw material segregation does not occur when the mixture is discharged.

In order to suppress the fluctuation of the heat shrinkage behavior of the long film, it is preferable to employ the above 5 means in addition to the above 1 to 4 means.
As a stretching method, not only horizontal uniaxial stretching with a tenter, but also stretching in the longitudinal direction of 1.0 to 4.0 times, preferably 1.1 to 2.0 times can be performed. The biaxial stretching may be either sequential biaxial stretching or simultaneous biaxial stretching, and may be re-stretched as necessary. Further, in sequential biaxial stretching, any of stretching methods such as vertical and horizontal, horizontal and vertical, vertical and horizontal and horizontal and vertical and horizontal directions may be used. Even when these longitudinal stretching steps or biaxial stretching steps are adopted, the film roll of the present invention is subject to fluctuations in the film surface temperature measured at a fixed position in the preheating step, stretching step, etc., similarly to the transverse stretching. Within the range of the distance in the flow direction corresponding to the film winding length, the average temperature is preferably within ± 1 ° C, and more preferably within the average temperature ± 0.5 ° C.

  The heat-shrinkable film roll in the present invention is a heat-shrinkable film roll obtained by winding a heat-shrinkable film around a core and winding a width of 200 mm or more and a length of 300 m or more. A film roll having a width of less than 200 mm is of low industrial utility value, and a film roll having a length of less than 300 m is less likely to exhibit the effects of the present invention. As for the width | variety of the heat-shrinkable film roll in this invention, 300 mm or more is more preferable, and 400 mm or more is further more preferable. The length of the heat-shrinkable film roll is more preferably 400 m or more, and further preferably 500 m or more. The upper limit of the width and winding length of the film roll is not particularly limited, but generally it is 1500 mm or less in width for ease of handling, and the winding length is about 6000 m or less when the film thickness is 45 μm. In addition, the winding core in the present invention refers to a paper tube of 3 inches, 6 inches, 8 inches, or the like, a plastic core, or a metal core that serves as a core of a film roll.

  Next, the present invention will be described in more detail using examples and comparative examples, but is not limited to the following examples. Moreover, the measuring method of the physical property of the film obtained by the Example and the comparative example is shown below.

(1) Confirmation of steady region and setting of sample cut-out portion From the second end portion (winding end portion) of the film about a film roll wound with a film having a length of 1000 m obtained in Examples and Comparative Examples described later. Samples of 5 points were cut out at intervals of 20 m, samples of 5 points were cut out at intervals of 20 m from the first end (winding start portion) of the film, and the thermal shrinkage rate (described later) of these samples in the maximum shrinkage direction was measured. The thermal contraction rate of each sample was within 20%. Moreover, the production / stretching process was stable during the production of the film. Therefore, it was confirmed that each film roll corresponds to the steady region over the entire length of the film.

(2) The heat shrinkage film in the maximum shrinkage direction is cut into a 10 cm × 10 cm square along the longitudinal direction and the direction orthogonal thereto, and treated in warm water of 85 ° C. ± 0.5 ° C. for 10 seconds without load. Then, the sample was immersed in water at 25 ° C. ± 0.5 ° C. for 10 seconds, and then the lengths of the sample in the vertical and horizontal directions were measured, and the thermal shrinkage rate was determined according to the following formula.
Heat shrinkage rate (%) = (length before shrinkage−length after shrinkage) ÷ length before shrinkage × 100

(3) In the measurement of the heat shrinkage rate in the maximum shrinkage direction, the heat shrinkage rate was also obtained in the direction perpendicular to the maximum shrinkage direction.

(4) Maximum heat shrinkage stress value A sample having a length in the maximum shrinkage direction of 200 mm and a width of 20 mm is prepared, and the inside of the heating furnace of the tensile tester (“Tensilon” manufactured by Toyo Seiki Co., Ltd.) equipped with a hot air heating furnace is 90 ° C. , Stop blowing and set the sample in the heating furnace. The distance between chucks is 100 mm (constant). The heating furnace door is quickly closed, air blowing (90 ° C., blowing speed 5 m / sec) is resumed, and heat shrinkage stress is detected and measured. The maximum value was read from the chart, and this was taken as the maximum heat shrink direction (MPa). The results are shown in Table 8.

(5) Solvent adhesiveness Solvent adhesiveness was controlled by adjusting the temperature to 30 ± 1 ° C and relative humidity 85 ± 2% by slitting the film roll to a width of 273 mm over the entire length of the film roll and winding it again into a roll shape. For 250 hours, and after printing three colors with grass, gold and white inks manufactured by Toyo Ink Co., Ltd., using a tube forming device, slightly inward from the edge of one side of the film. Tetrahydrofuran was applied in a width of 2 ± 1 mm (application amount: 3.0 ± 0.3 g / mm ² ), the film was immediately rolled up, the ends were overlapped and bonded, and processed into a tube (processing speed: 80 m / min) ). The tube was rolled up in a flat and crushed state.
A sample is cut out from the tube roll. The first sample cut-out part was the end of the tube winding (0 m from the end of winding), and the final cut-out part was the start of the tube winding (0 m from the start of winding), and a total of 11 samples were collected. The tube-shaped sample obtained from each sample cut-out part was cut open so that the adhesion location was in the center, and a film-shaped sample was obtained. From this film-like sample, a film test piece (n = 10) having a length of 100 m and a width of 15 mm was cut out, and this film-like test piece was set at a distance between chucks of 50 mm (“STM made by Baldwin”). -T ") so that the solvent-bonded portion is positioned in the center of the chucks, and a tensile test is performed at a temperature of 23 ° C and a pulling speed of 200 mm / min to measure the peel strength of the bonded portion. The solvent adhesive strength.

(6) Shrinkage Finishing Property Of the tube prepared in (4), the entire amount of the tube that was not used for the measurement of the solvent adhesive strength was cut to prepare a heat-shrinkable film label. A heat-shrinkable film label is attached to a 0.9L square PET bottle, and the tunnel passage time is 10 seconds, 1 zone temperature / 2 zone temperature in a steam tunnel (model: SH-1500-L) manufactured by Fuji Astex. = The entire amount of the label produced under the condition of 80 ° C / 90 ° C was allowed to pass, and the shrinkage finish property was judged visually. Shrinkage finish is evaluated by a five-step evaluation, 5: Best finish, 4: Good finish, 3: Slight defects (within 2 locations), 2: Defects (3-5 locations), 1: Many defects (6 As a result, the shrinkage finished defective rate (%) was determined according to the following formula. Here, the defects are wrinkles, label edge folding, color spots, and insufficient shrinkage.
Shrinkage finished defective rate = 100 × number of defective samples / total number of samples

(Raw polymer)
Using the following raw material polymers having the composition shown in Table 1, all raw material polymers were melt-extruded by an extruder, then strand cut and adjusted to the raw material sizes in Table 1 were used.
Chip A: SPX78H3 manufactured by Sumitomo Chemical Co., Ltd.
Chips B and C: Alcon P140 (softening temperature 140 ° C) manufactured by Arakawa Chemical Industries, Ltd. and S131 manufactured by Sumitomo Chemical Co., Ltd.
Chip D: APEL6011T manufactured by Mitsui Chemicals, Inc.
Chip E: S131 manufactured by Sumitomo Chemical Co., Ltd.
Chip F: FL6741G manufactured by Sumitomo Chemical Co., Ltd.
Chip GH: HYBRAR 7125 manufactured by Sumitomo Chemical Co., Ltd.

(Example 1)
Using two extruders, the outer layer / base material layer / outer layer structure (2 types, 3 layers) are laminated in a molten state so that the thicknesses of both outer layers are almost equal, extruded from a T die, and then cooled roll An unstretched sheet was obtained by casting above.
Using one extruder for the base material layer, as shown in Table 1, 34% of chip A, 47% of chip B, 5% of chip D, 14% of chip E, hopper directly above the extruder The mixture was mixed in the hopper while being continuously supplied separately with a metering screw feeder, and melt-extruded at 230 ° C. with a single-screw extruder. The hopper had a capacity of 100 kg of raw material chips, and the discharge rate of the extruder was 300 kg per hour. Then, using the other extruder for the outer layer, as shown in Table 1, the chip F is 39%, the chip G is 50%, the chip I is 2%, the chip J is 6%, and the chip K is 3%. While being fed separately and continuously to the hopper directly above the extruder with a fixed screw feeder, mixing in this hopper, melt extrusion at 230 ° C with a single screw extruder, and cooling with a cooling roll maintained at 20 ° C Solidified. The hopper had a capacity of 33 kg of raw material chips, and the discharge rate of the extruder was 100 kg per hour.
The unstretched film was preheated at 92 ° C. for 15 seconds, stretched 6 times at 76 ° C. in the transverse direction with a tenter, and then heat treated at 70 ° C. for 15 seconds while relaxing 8% in the width direction. A 50 μm heat-shrinkable polyolefin film was continuously formed over 1000 m. Here, in Example 1, the fluctuation of the film surface temperature when the film was continuously produced was the average temperature ± 0.8 ° C. in the preheating step, the average temperature ± 0.7 ° C. in the stretching step, and the average temperature in the heat treatment step. The temperature was controlled within a range of ± 0.5 ° C. 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).
The obtained film was slit to a width of 0.4 m and a length of 1000 m and wound up on a 3-inch paper tube to obtain a heat-shrinkable film roll. The physical property values of this film roll are shown in Tables 2 to 5.

(Example 2)
Using two extruders, the outer layer / base material layer / outer layer structure (2 types, 3 layers) are laminated in a molten state so that the thicknesses of both outer layers are almost equal, extruded from a T die, and then cooled roll An unstretched sheet was obtained by casting above.
Using one extruder for the base material layer, as shown in Table 1, 28% of chip A, 45% of chip B, 8% of chip D, 19% of chip E, hopper directly above the extruder The mixture was mixed in the hopper while being continuously supplied separately with a metering screw feeder, and melt-extruded at 230 ° C. with a single-screw extruder. The hopper had a capacity of 100 kg of raw material chips, and the discharge rate of the extruder was 300 kg per hour. Then, using the other extruder for the outer layer, as shown in Table 1, 41% of the chip F, 51% of the chip G, 2% of the chip I, 6% of the chip J, and the hopper directly above the extruder The mixture was mixed in the hopper while being separately supplied continuously with a quantitative screw feeder, melt-extruded with a single-screw extruder at 230 ° C., and cooled and solidified with a cooling roll maintained at 20 ° C. The hopper had a capacity of 33 kg of raw material chips, and the discharge rate of the extruder was 100 kg per hour.
The unstretched film was preheated at 90 ° C. for 15 seconds, stretched 6 times at 75 ° C. in the transverse direction with a tenter, and then heat-treated at 70 ° C. for 15 seconds while relaxing 8% in the width direction. A 50 μm heat-shrinkable polyolefin film was continuously formed over 1000 m. Here, in Example 1, the fluctuation of the film surface temperature when the film was continuously produced was the average temperature ± 0.7 ° C. in the preheating step, the average temperature ± 0.6 ° C. in the stretching step, and the average temperature in the heat treatment step. Control was within the range of ± 0.6 ° C.
The obtained film was slit to a width of 0.4 m and a length of 1000 m and wound up on a 3-inch paper tube to obtain a heat-shrinkable film roll. The physical property values of this film roll are shown in Tables 2 to 5.

(Comparative Example 1)
As shown in Table 1, 34% of chip A, 47% of chip C, 5% of chip D, and 14% of chip E were mixed in advance using one extruder for the base material layer. Then, 350 kg of raw material chips and 60 hoppers with the same inclination angle of 60 ° are arranged in series, and the mixture is put in the hopper on the most upstream side, the second, third, fourth ( A heat-shrinkable polyolefin film roll having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the final hopper was moved to each hopper. The physical property values of the film rolls obtained are shown in Tables 2-5.

(Comparative Example 2)
As shown in Table 1, using one extruder for the outer layer, chip F 39%, chip H 50%, chip I 2%, chip J 6%, chip K 3% in advance Mixed. Then, 4 hoppers of the same shape with a raw material chip of 35 kg and a hopper inclination angle of 60 ° are arranged in series, and the mixture is put into the uppermost hopper, the second, third, fourth ( A heat-shrinkable polyolefin film roll having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the final hopper was moved to each hopper. The physical property values of the film rolls obtained are shown in Tables 2-5.

(Comparative Example 3)
In Example 1, the fluctuation of the film surface temperature when continuously producing the film was as follows: average temperature ± 1.2 ° C. in the preheating step, average temperature ± 2.7 ° C. in the stretching step, and average temperature ± 2.5 in the heat treatment step. A heat-shrinkable polyolefin film roll was obtained in the same manner as in Example 1 except that the temperature was controlled within the range of ° C. The physical property values of the film rolls obtained are shown in Tables 2-5.

  The heat-shrinkable polyolefin film roll of the present invention has little compositional and physical property fluctuations of a long film wound around the film roll, defects in the solvent bonding process, insufficient shrinkage in the heat shrinking process, shrinkage spots The occurrence of defects due to the occurrence of wrinkles, distortion, vertical shrinkage, etc. is extremely small. In addition, the method for producing a heat-shrinkable polyolefin roll of the present invention can easily reduce the fluctuation of the polymer composition and the fluctuation of the heat-shrinking behavior of the long film, and is very useful for industrial production.

Claims (9)

A film roll formed by winding a heat-shrinkable polyolefin film, wherein the heat-shrinkable polyolefin film satisfies the following requirements (1) and (2): .
When the end of the film in the steady region where the film properties are stable in the length direction of the film is the first end, and the end on the end of the winding is the second end, the second end The first sample cutout portion is provided within 2 m of the first end portion, the final cutout portion is provided within 2 m inside the first end portion, and the sample cutout portion is provided about every 100 m from the first sample cutout portion. Each sample cut into a 10 cm × 10 cm square shape was immersed in hot water at 85 ° C. for 10 seconds and then pulled up, then immersed in water at 25 ° C. for 10 seconds, and the heat shrinkage rate in the maximum heat shrinkage direction was It is 20% or more for all samples.
For each sample appropriately cut out from each sample cutout section described in (1) above, when the average value of the heat shrinkage rate in the maximum heat shrinkage direction of the cut sample was calculated, the heat shrinkage rate of all the samples Is within this average value ± 5%. A film roll formed by winding a heat-shrinkable polyester film, wherein the heat-shrinkable polyester film satisfies the requirement (1) according to claim 1 and satisfies the following requirement (3). A heat-shrinkable polyester film roll.
The maximum shrinkage direction of all the samples when the average value is calculated by measuring the heat shrinkage stress in the maximum shrinkage direction for each sample appropriately cut out from each sample cutout portion described in requirement (1) of claim 1 When the average value of these maximum heat shrinkage stresses was calculated, the maximum heat shrinkage stress values of all the samples were within this average value ± 1.0 MPa. Yes. A film roll formed by winding a heat-shrinkable polyolefin film, wherein the heat-shrinkable polyolefin film satisfies the requirement (1) according to claim 1 and the following requirement (4). A heat-shrinkable polyolefin film roll.
Each sample cut to 10 cm × 10 cm from each sample cut-out portion appropriately cut out from each sample cut-out portion described in requirement (1) of claim 1 is dipped in hot water of 85 ° C. for 10 seconds and pulled up Then, when the sample was immersed in water at 25 ° C. for 10 seconds and pulled up, the heat shrinkage rate in the direction orthogonal to the maximum shrinkage direction of all the samples was within 7%, and the average value of the heat shrinkage rates in these orthogonal directions was When calculated, the thermal contraction rate in the orthogonal direction of all the samples is within the range of ± 2% of this average value. A film roll formed by winding a heat-shrinkable polyolefin film, wherein the heat-shrinkable polyolefin film satisfies the requirement (1) according to claim 1 and the following requirement (5). A heat-shrinkable polyolefin film roll.
A film in a steady region where the film properties are stable in the length direction of the film is appropriately slit in the length direction, and both sides of the slit film are overlapped with each other and solvent-bonded with tetrahydrofuran to form a tube. About the tube roll obtained by winding in the crushed state, the first sample cutout portion is provided within 2 m inside the tube winding end, and the final cutout portion is provided within 2 m inside the tube winding start, and 1 Sample cut-out portions are provided approximately every 100 m from the second sample cut-out portion, and the tube-like sample obtained from each sample cut-out portion is cut open to form a film-like test piece having a width of 15 mm. Set to the tensile tester set at the center of the chuck so that the solvent adhesion portion is located at the center of the chucks. When the solvent adhesion strength was measured by conducting a tensile test at a pulling speed of 200 m / min, the solvent adhesion strength of all samples was 1 N / 15 mm width or more, and when the average value of these samples was calculated, all samples The solvent adhesive strength is within the range of ± 2 N / 15 mm width of this average value.   The heat-shrinkable polyolefin film roll according to any one of claims 1 to 4, wherein a heat-shrinkable polyolefin film having a width of 0.2 m or more and a length of 300 m or more is wound. A method for producing a heat-shrinkable polyolefin film roll, comprising a step of mixing a polymer having the largest amount of use and one or more other polymers having different compositions from each other and melt-extruding the polymer.
The shape of the 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 the raw material chips of polymers other than the most used polymer are the raw material chips of the most used polymer. The average major axis (mm), the average minor axis (mm), and the average tip length (within ± 20% of the major axis (mm), average minor axis (mm), and average tip length (mm), respectively. mm), and a method for producing a heat-shrinkable polyolefin film roll.   A method for producing a heat-shrinkable polyolefin-based film comprising a step of melt-extruding a film using an extruder equipped with a funnel-shaped hopper as a raw material chip supply unit, wherein the discharge amount per hour of the extruder is used as the hopper A method for producing a heat-shrinkable polyolefin film roll, wherein a hopper having a capacity of 15 to 120% by mass is used.   A method for producing a heat-shrinkable film roll by drawing a film obtained by cooling after melting and extruding a raw material polymer, or after cooling and then stretching, after a preheating step, a stretching step and stretching The heat shrinkable polyolefin film is characterized in that the fluctuation range of the surface temperature of the film measured at an arbitrary point in each of the heat treatment steps is controlled within the range of the average temperature ± 1 ° C. over the entire length of the film. Method.   A method for producing a heat-shrinkable polyolefin film, wherein the heat-shrinkable film roll is allowed to stand in an atmosphere of 40 ° C. ± 1 ° C. for 6 hours to 24 hours after film formation.