JP2017035882A - Method for producing haet-shrinkable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a heat-shrinkable film having small variation in shrinkage at the center and end part in the width direction.SOLUTION: There is provided a method for producing a heat-shrinkable film having a film width W (mm) of 1,000 mm or more, which comprises a step MD1 of stretching the film in a longitudinal direction, wherein a film width W1 (mm) before MD1 and a film width W2 (mm) after MD1 satisfy the following expression (I), and the W2 (mm) and the stretching magnification (factor) of MD1 satisfy the expression (II). 0.8≤(W2)/(W1)<1 (1), 400≤(W2)/(the stretching magnification of MD1)≤6,000 (2)SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a heat-shrinkable film, and more particularly to a method for producing a heat-shrinkable film having a small variation in shrinkage rate at the center and end in the width direction even when the width is 1000 mm or more.

The heat-shrinkable film is used for a wide range of applications such as packaging and labeling. Examples include labeling for bottle containers such as tea and soft drinks, packaging applications such as multi-shrink applications, and decorative applications that give high-design designs to complex-shaped members using film shrinkage. It is done. For these applications, a uniaxially stretched film as typified by Patent Documents 1 and 2 and a film that contracts only in a specific direction by stretching in the transverse direction and then biaxially stretching in the longitudinal direction have been proposed. .
The heat shrink film is required to be commercialized in a wide range from the viewpoint of suppressing the manufacturing cost by printing and processing a large area at a time, but based on the proposal listed in Patent Document 1 or 2. It was found that even when a film having a width of 1000 mm or more was sampled, the variation in shrinkage rate in the width direction increased. Specifically, for example, a phenomenon in which the thermal shrinkage rate at the end portion of the film is lower than that at the center portion of the film is observed, and in some cases, a wide film cannot obtain sufficient characteristics at the end portion. Therefore, even when a wide sample of 1000 mm or more is used, a film having a uniform shrinkage at the center and end in the width direction is required.

JP 2011-79229 A International Publication No. 2014/021120

Therefore, the present invention aims to solve the above-mentioned drawbacks and provide a method for producing a film having a uniform shrinkage at the center and the end in the width direction even when a wide sample of 1000 mm or more is obtained.

In order to solve the above problems, the present invention has the following configuration.
(1) A method for producing a heat-shrinkable film having a film width W (mm) of 1000 mm or more, comprising a step (MD1) of stretching in the longitudinal direction, and a film width W1 (mm) before MD1 and after MD1 The film width W2 (mm) satisfies the following formula (I), and the W2 (mm) and MD1 draw ratio (times) satisfy the formula (II): Production method.
0.8 ≦ (W2) / (W1) <1 (I)
400 ≦ (W2) / (MD1 draw ratio) ≦ 6000 (II)
(2) The method for producing a heat-shrinkable film according to (1), wherein the step (MD1) of stretching in the longitudinal direction is a roll heating method.
(3) The average value TE1 (μm) of the thickness at both ends of the width direction position of the film before the step (MD1) of stretching in the longitudinal direction and the thickness TC1 (μm) at the center satisfy the following formula (III). (1) The manufacturing method of the heat-shrinkable film as described in (2).
1.2 ≦ (TE1) / (TC1) ≦ 50 (III)
(4) The average value TE2 (μm) of the thickness at both ends of the film in the width direction after the step (MD1) of stretching in the longitudinal direction and the thickness TC2 (μm) of the center satisfy the following formula (IV). The manufacturing method of the heat-shrinkable film in any one of (1)-(3).
1.2 ≦ (TE2) / (TC2) ≦ 50 (IV)
(5) The heat-shrinkable film according to any one of (1) to (4), wherein TE1 (μm), TC1 (μm), TE2 (μm), and TC2 (μm) satisfy the following formula (V): Production method.
0.9 ≦ {(TE2) / (TC2)} / {(TE1) / (TC1)} ≦ 2 (V)
(6) The method for producing a heat-shrinkable film according to any one of (1) to (5), wherein the heat-shrinkable film comprises a polyester resin as a main constituent component.

The heat shrinkable film manufacturing method of the present invention can obtain a film having uniform shrinkage at the center and end in the width direction even when it is a wide sample of 1000 mm or more. It is preferably used as a film production method.

Hereinafter, the heat shrinkable film manufacturing method of the present invention will be described in detail.
The method for producing a heat-shrinkable film of the present invention is a method for producing a heat-shrinkable film having a film width W (mm) of 1000 mm or more, and has a step (MD1) of stretching in the longitudinal direction, and the film before MD1 It is important that the width W1 (mm) and the film width W2 (mm) after MD1 satisfy the following formula (I).
0.8 ≦ (W2) / (W1) <1 (I)
If the film width W (mm) is less than 1000 mm, the area of the film that can be printed and processed at a time is reduced, which may increase the manufacturing cost of various film processed products used in packaging and decoration applications. . The film width W (mm) is preferably as wide as possible, but is preferably 7000 mm or less and more preferably 5000 mm or less from the viewpoint of width restrictions of the film stretching equipment, printing, and processing equipment.
(W2) / (W1) indicates the width dimension retention ratio before and after the step (MD1) of stretching in the longitudinal direction, and if it is less than 0.8, the shrinkage in the width direction during the MD1 step increases. In some cases, the orientation axis of the film after the MD1 step is distorted, and the shrinkage is uneven at the center and the end in the width direction of the film. (W2) / (W1) is preferably 0.85 or more, and more preferably 0.9 or more, from the viewpoint of improving uniform shrinkage at the center and end in the width direction. Moreover, although (W2) / (W1) is so preferable that it is large, since it is difficult to eliminate shrinkage | contraction in the width direction completely at an extending | stretching process, the realistic upper limit is less than one.
Specific methods for setting (W2) / (W1) within the range of the formula (I) include a method of adjusting manufacturing conditions such as a draw ratio and film thicknesses at both ends. Among them, a method of increasing the film thickness at both ends of the film before the MD1 step, which will be described later, a method of changing the heating method at the MD1 step to a roll heating method, and the like are effective. By making both end portions of the film before the MD1 process thicker than the central portion, the frictional force applied to the film during MD1 stretching is concentrated on both end portions, and when the both end portions of the film try to shrink to the central portion, Since it becomes difficult to shrink, the film shrinkage at the time of extending | stretching can be suppressed. In addition, by adopting a roll heating method, for example, the roll can be brought into contact until immediately before the stretching process between rolls having a difference in peripheral speed, and the stretching section can be controlled to be short, so that the shrinkage of the film during stretching can be suppressed. Is advantageous.
In the method for producing a heat-shrinkable film of the present invention, it is important that the film width W2 (mm) after MD1 and the draw ratio (times) of MD1 satisfy the formula (II).
400 ≦ (W2) / (MD1 draw ratio) ≦ 6000 (II)
(W2) / (MD1 draw ratio) is a value obtained by dividing W2 which is the film width after MD1 by the draw ratio of MD1 (unit is expressed in mm / times). The larger the W2, the larger the film width W of the final product, and the smaller the MD1 draw ratio, the better the uniform shrinkage at the center and end in the width direction. (W2) / (MD1 stretch The larger the (magnification), the wider the width, and the better the uniform shrinkability at the center and end in the width direction. If (W2) / (MD1 draw ratio) is less than 400, the uniform shrinkage at the center and end in the width direction may be insufficient. In addition, since the film width of the final product is less than 1000 mm and the area of the film that can be printed and processed at a time is reduced, the manufacturing cost of various film processed products may increase. From the viewpoint of increasing the uniform shrinkability in the width direction and the film width of the final product, (W2) / (stretching ratio of MD1) is preferably 500 or more, more preferably 600 or more, and particularly preferably 700 or more. If (W2) / (MD1 draw ratio) exceeds 6000, the film width is too wide to be compatible with film stretching equipment, printing and processing equipment, or the draw ratio is small and the heat shrinkability is insufficient. It may become. From the standpoint of adaptability to various facilities and good heat shrinkability, (W2) / (MD1 draw ratio) is preferably 4000 or less, more preferably 3500 or less, and particularly preferably 3000 or less.
Specific methods for setting (W2) / (MD1 draw ratio) in the range of the formula (II) include a method of adjusting production conditions such as draw ratio and film thickness at both ends. In particular, in order to satisfy the formula (II) while keeping (W2) / (W1) within the range of the formula (I), it is important to suppress the width shrinkage in the MD1 step described later. Effective methods include thickening and a roll heating method in the MD1 process. By thickening both end portions before the MD1 process, the frictional force applied to the film during MD1 stretching is concentrated on both end portions, and when the both end portions of the film try to contract to the center portion, it becomes difficult to contract due to the frictional force. Therefore, film shrinkage during stretching can be suppressed. In addition, by adopting a roll heating method, for example, the roll can be brought into contact with the roll until immediately before the stretching process between the rolls with a difference in peripheral speed, and the stretching section can be controlled to be short, so that the film shrinkage during stretching can be suppressed. Is advantageous.
The manufacturing method of the heat-shrinkable film of the present invention may include a step of stretching in at least one of the longitudinal direction and / or the width direction at an arbitrary stage before and after the MD1 step. The stretching method may be either the inflation method or the flat method for the MD1 step and any other stretching step. Here, the inflation method is a stretching method in which a tubular molten resin extruded from a circular die is expanded by an internal gas pressure, and the flat method is a roll convergence of a sheet-shaped molten resin extruded by a T die or the like. This is a stretching method that expands in the in-plane direction of the sheet-like resin by utilizing the difference, speed change of the clip, and width change. From the viewpoint of easy control of film thickness and a film width W (mm) of 1000 mm or more, the flat method is preferably used. Moreover, the extending | stretching method of the flat method is divided roughly into the wet extending | stretching method and the dry-type extending | stretching method, and may use any. Here, the wet stretching method is a stretching method in which stretching is performed in a heated solvent tank, and the dry stretching method is a method in which the film is stretched by heating with hot air or roll heating. Further, the wet stretching method and the dry stretching method may be used in combination. From the viewpoint of easily raising the stretching temperature and not requiring drying (removal) of the solvent, the dry stretching method is preferable. In the dry stretching method, various heating methods such as a radiation heating method, a hot air heating method, a hot plate heating method, and a roll heating method are used, and these methods may be combined. Here, the radiant heating method is a method in which the film is heated and stretched by an infrared (IR) heater or the like, and the hot air heating method and the hot plate heating method are methods in which a film is heated and stretched by circulating hot air or a heating plate, respectively. Yes, the roll heating method is a method in which the film is stretched by heating with a heating roll. In addition, the stretching method is a roll stretching method that stretches due to the difference in peripheral speed between the low-speed roll group and the high-speed roll group, and tenter stretching that grips both ends of the film with clips, etc. Various methods such as a method are used.
In the method for producing a heat-shrinkable film of the present invention, the step of stretching in the longitudinal direction (MD1) may employ any method such as a roll stretching method or a tenter stretching method, but the uniform shrinkability in the width direction. From this point of view, a roll stretching method is preferable, and among the roll stretching methods, a combination with a roll heating method in which a film is heated and stretched by a heated roll is more preferable.

In the method for producing a heat-shrinkable film of the present invention, the average value TE1 (μm) of the thickness at both ends of the width direction position of the film before the step of stretching in the longitudinal direction (MD1) and the thickness TC1 (μm) at the center are as follows. It is preferable that the following formula (III) is satisfied.
1.2 ≦ (TE1) / (TC1) ≦ 50 (III)
(TE1) / (TC1) is an index of how thick both end portions of the film before the step (MD1) of stretching in the longitudinal direction are with respect to the center portion of the film. In the case of the roll stretching method, the contact portion between the film and the roll is concentrated on the end portion, and therefore, the center portion of the film is preferable because the contact area with the roll is reduced and the quality is improved. In addition, it is preferable that (TE1) / (TC1) is 50 or less because thickness unevenness and heat shrinkage unevenness in the width direction of the film can be reduced. (TE1) / (TC1) is more preferably 1.2 or more and 45 or less, particularly preferably 1.2 or more and 40 or less, and most preferably 1.2 or more and 30 or less.

  As a specific method for setting (TE1) / (TC1) within the range of the formula (III), a method for adjusting the lip width of the die for discharging the sheet before stretching so that the width of the end portion becomes large, etc. Is mentioned.

The manufacturing method of the heat-shrinkable film of the present invention includes the average value TE2 (μm) of the thickness at both ends of the width direction position of the film after the step of stretching in the longitudinal direction (MD1) and the thickness TC2 (μm) at the center. Preferably satisfies the following formula (IV).
1.2 ≦ (TE2) / (TC2) ≦ 50 (IV)
(TE2) / (TC2) is an index of how thick both ends of the film after the step of stretching in the longitudinal direction (MD1) are with respect to the center of the film. In the case of the roll stretching method, when the roll is transported after the step of stretching in the longitudinal direction (MD1), the contact portion between the film and the roll is concentrated on the end portion, so that the central portion of the film does not touch the roll so much and the quality is low. Since it becomes favorable, it is preferable. Moreover, it is preferable that (TE2) / (TC2) is 50 or less because thickness unevenness and heat shrinkage unevenness in the width direction of the film can be reduced. (TE2) / (TC2) is more preferably 1.2 or more and 45 or less, particularly preferably 1.2 or more and 40 or less, and most preferably 1.2 or more and 30 or less.

  As a specific method for setting (TE2) / (TC2) within the range of the formula (IV), a method of adjusting the lip width of the die for discharging the sheet before stretching so that the width of the end portion becomes large, etc. Is mentioned.

The manufacturing method of the heat-shrinkable film of the present invention includes an average value TE1 (μm) of thicknesses at both ends of the width direction position of the film before the step (MD1) of stretching in the longitudinal direction and a thickness TC1 (μm) of the central part, In addition, the average value TE2 (μm) of the thickness at both ends at the position in the width direction of the film after the step (MD1) of stretching in the longitudinal direction and the thickness TC2 (μm) at the center satisfy the following formula (V). preferable.
0.9 ≦ {(TE2) / (TC2)} / {(TE1) / (TC1)} ≦ 2 (V)
{(TE2) / (TC2)} / {(TE1) / (TC1)} is how thick both ends of the film are before and after the step (MD1) of stretching in the longitudinal direction with respect to the center of the film. If it is 0.9 or more, for example, the contact part of the film and the roll immediately after stretching concentrates at the end, so the central part of the film does not touch the roll just after stretching so the quality is good. Therefore, it is preferable. Moreover, it is preferable that {(TE2) / (TC2)} / {(TE1) / (TC1)} is 2 or less because thickness unevenness and heat shrinkage unevenness in the width direction of the film can be reduced. {(TE2) / (TC2)} / {(TE1) / (TC1)} is more preferably 1.0 or more and 1.8 or less, and particularly preferably 1.05 or more and 1.9 or less. Most preferably, it is 1 or more and 1.8 or less.
As a specific method for bringing {(TE2) / (TC2)} / {(TE1) / (TC1)} into the range of the formula (V), the lip width of the die for discharging the sheet before stretching is as follows: Examples include a method in which the width of the end portion is adjusted and the elastic modulus of the film before stretching is adjusted so that the center portion is more easily stretched than the both end portions of the film. Examples of the method for adjusting the modulus of elasticity of the film before stretching include a method in which the stretching temperature is 20 ° C. or higher than the glass transition temperature of the polymer, and more preferably 30 ° C. or higher, (MD1) before the step In the film production, the temperature of the die, which will be described later, is made higher at the end than at the center, so that the thermal decomposition of the resin at the end (mainly crystalline resin) proceeds to reduce the molecular weight, and the (MD1) step The method of making the edge part of the previous film have a higher degree of crystallinity, the method of making the crystallinity state of the edge part high by performing heat treatment only on the edge part of the film before the (MD1) step, etc. Can be mentioned.

In the method for producing a heat-shrinkable film of the present invention, the constituent components of the heat-shrinkable film are not particularly limited as long as the effects of the present invention are exhibited. For example, polyolefin resins such as polypropylene and polyethylene, cyclic Olefin resins, Polyethylene terephthalate, Polypropylene terephthalate, Polybutylene terephthalate, and other polyester resins, Acrylic resins, Polyvinylidene fluoride, Polytetrafluoroethylene, Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers, Tetrafluoroethylene / Hexafluoro Fluorine resins such as propylene copolymer, tetrafluoroethylene / ethylene copolymer, polychlorotrifluoroethylene, chlorotrifluoroethylene / ethylene copolymer, polycarbonate Resin, polyurethane resin, polyvinyl chloride resin, polystyrene resin, ABS (acrylonitrile / butadiene / styrene copolymer) resin, AS (acrylonitrile / styrene copolymer) resin, triacetyl cellulose resin, triacetate Resin, urethane resin, polyamide resin and the like. From the viewpoint of easily exhibiting shrinkage, polyolefin resins, polyamide resins, polystyrene resins, and polyester resins are preferable, and polyester resins are particularly preferable. Further, from the viewpoint of improving the shrinkage characteristics, when the resin as the main constituent component of the heat-shrinkable film is a polyester resin, the resin preferably has crystallinity. Here, as a method for judging the crystallinity of the resin, for example, in differential scanning calorimetry measured according to JIS K-7121-1987 and JIS K-7122-1987, the temperature is 25 ° C. to 20 ° C./min. It can be judged whether or not an endothermic peak is seen from the DSC curve when the temperature is raised to (that is, if the endothermic peak is seen, the resin is crystalline). Moreover, it can be judged that the crystallinity of the resin is higher as the crystal melting energy obtained from the obtained DSC curve is larger.
In the present invention, when a polyester resin is used as the main component of the heat-shrinkable film, it is preferable that ethylene glycol is 80 mol% or more as a glycol or a derivative thereof constituting the polyester resin. For example, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl Aliphatic dihydroxy compounds such as aliphatic dihydroxy compounds such as glycol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, 1,4-cyclohexanedimethanol and spiroglycol Things, bisphenol A, aromatic dihydroxy compound such as bisphenol S, and may contain a derivative thereof.

Moreover, as dicarboxylic acid or its derivative, terephthalic acid is preferably 80 mol% or more, but as other components, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyl Aromatic dicarboxylic acids such as sulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid Examples thereof include alicyclic dicarboxylic acids such as oxycarboxylic acids such as paraoxybenzoic acid, and derivatives thereof. Examples of dicarboxylic acid derivatives include dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimer. An esterified product may be contained.
The heat-shrinkable film obtained by the production method of the present invention has uniform shrinkage characteristics at the center and end of the film even at a width of 1000 mm or more. It can use preferably for a use.
In addition, the heat-shrinkable film obtained by the production method of the present invention can be formed with various functional layers such as a printed layer, a light-resistant layer, a weather-resistant layer, an adhesive layer, an adhesive layer, and a vapor-deposited layer. In addition to being layered on a heat-shrinkable film, the layer can be heat-shrinked and used, and after functional layers are layered on a heat-shrinkable film, the film is heat-shrinked and then released, and then peeled off. Can be used as a film.

  The characteristic measuring method and the effect evaluating method in the present invention are as follows.

(1) Film width W, W1, W2
The film width W is determined by measuring the distance between both ends of the film using a steel tape measure (manufactured by Yamayo Measuring Instruments, Styron Custom “NC10”) after placing the film sample unrolled from the product roll on a flat surface. Determined by measurement. The film width W1 before the MD1 step was measured by measuring the width before the MD1 step in the same manner as the film width W. The film width W2 after the MD1 step was measured by the same method as the film width W for a sample obtained after the film for which the measurement of W1 was completed was put into the MD1 step. The measurement was performed 5 times in total by shifting the position by 50 mm in the longitudinal direction of the film, and the average value of these 5 times was adopted.

(2) Stretch ratio In the case of the roll stretching method, the peripheral speed of the roll installed at the beginning of the stretch roll group and the roll installed at the end of the stretch roll group is measured, and the peripheral speed of the last roll is determined. The value divided by the peripheral speed of the first roll was taken as the draw ratio. In the case of the tenter method, the clip speed at the tenter entrance and the clip speed at the tenter exit were measured, and the value obtained by dividing the clip speed at the exit by the clip speed at the entrance was taken as the draw ratio.

(3) The film thickness was measured using a film thickness dial gauge (Mitutoyo, 2046S). The measurement was carried out for a total of three locations: the central portion determined from the film width of (1) and the position on the central portion side in the film width direction of 5 mm from both end portions of the film. The measurement was performed 5 times in total by shifting the position by 50 mm in the longitudinal direction of the film per location, and the average value of the thickness of 5 times was obtained. For the central part, an average value of five times of thickness was adopted, and TC1 and TC2 were set according to the process. About both ends, the average value of the thickness measured 5 times at each end, that is, 10 times in total was adopted, and it was set as TE1 and TE2 according to the process.

(4) A sample obtained by cutting the heat shrinkage film into a size of 150 mm × 10 mm width in the longitudinal direction of the roll product is marked at both end positions with an interval of 100 mm (L0), and a 3 g weight is suspended to 110 ° C. Heat treatment was performed by placing in a heated hot air oven for 30 minutes. The distance between marked lines (L1) after heat treatment was measured, and the heat shrinkage rate was calculated by the following formula from the change in the distance between marked lines before and after heating. The measurement was carried out with 5 samples and evaluated with an average value. In addition, the measurement location was made into the center part calculated | required by (3), and was made into a total of five places of the both ends and the intermediate position (2 places) of a center part and each edge part. For both ends, an average value of measurement of 5 samples measured at each end, that is, a total of 10 samples was adopted. For the middle position (two locations) between the center portion and each end portion, the average value of the measurement of 5 samples measured at each location, that is, a total of 10 samples was adopted. In the table, the heat shrinkage rate at the center of the film is denoted as SC, the heat shrinkage rate at the end of the film as SE, and the heat shrinkage rate at the middle position between the film center and the edge as SCE.
Thermal contraction rate (%) = 100 × (L0−L1) / L0
(5) Uniformity of shrinkage rate Based on the thermal shrinkage rate obtained in (4), the difference between the thermal shrinkage rate SE of the film edge and the thermal shrinkage rate SC of the film center, / The difference between the thermal shrinkage rate SCE at the middle position of the edge and the thermal shrinkage rate SC at the center of the film was calculated and judged according to the following criteria.
Difference between SE and SC = (SE−SC) / SC × 100
Difference between SCE and SC = (SCE−SC) / SC × 100
S: The difference between SE and SC, and the difference between SCE and SC are both 10% or less. A: The difference between SCE and SC is 10% or less, and the difference between SE and SC exceeds 10% and 16% or less. B: Difference between SE and SC, difference between SCE and SC both exceeds 10% and less than 16% C: Difference between SE and SC, difference between SCE and SC exceeds 16% Value D: A value in which the difference between SE and SC and the difference between SCE and SC both exceeded 16% (6) The thermal shrinkage ratio SC at the center in the width direction of the shrinkable film was measured and judged according to the following criteria.
A: Shrinkage rate is 20% or more B: Shrinkage rate is 10% or more and less than 20% C: Shrinkage rate is less than 10% (7) Film quality After 10 A4 size samples are cut out at the center in the width direction of the film The film surface was observed under a three-wavelength fluorescent lamp, and the number of scratches with a length of 5 mm or more that could be recognized was counted. The total amount of 10 scratches was determined and judged according to the following criteria.
A: 5 or less scratches B: 6 or more and 10 or less scratches C: 11 or more scratches (8) Wide workability The film width was measured by the method of (1) and judged according to the following criteria.
○: Film width W is 1000 mm or more x: Film width W is less than 1000 mm (resin as a main component of the film)
(9) Glass transition temperature Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., RDC220), measurement and analysis were performed in accordance with JIS K7121-1987 and JIS K7122-1987. Using 5 mg of resin raw material as a sample, the specific heat change based on the transition from the glass state to the rubber state when the temperature was raised from 25 ° C. to 300 ° C. at 20 ° C./min was read. An intermediate point where the straight line parallel to the straight line (intermediate point) at the same distance (intermediate point) in the direction of the vertical axis (the axis indicating the heat flow) from the straight line obtained by extending each base line intersects with the curve of the step change portion of the glass transition The point glass transition temperature was determined and used as the glass transition temperature of the resin raw material.

(10) Melting point Measurement and analysis were performed in accordance with JIS K-7121-1987 and JIS K-7122-1987 using a differential scanning calorimeter (Seiko Denshi Kogyo's RDC220). Using 5 mg of resin raw material as a sample, the temperature at the top of the endothermic peak obtained from the DSC curve when the temperature was raised from 25 ° C. to 300 ° C. at 20 ° C./min was taken as the melting point.

  In carrying out the examples of the present invention, the following raw materials were used.

(PET)
Polyethylene terephthalate is agglomerated silica having a number average particle diameter of 0.2 μm to a polyethylene terephthalate resin (inherent viscosity 0.65) having a terephthalic acid component of 100 mol% as a dicarboxylic acid component and an ethylene glycol component of 100 mol% as a glycol component. A polyester resin compounded to be 0.5% by weight based on 100% by weight of the total resin. The glass transition temperature was 78 ° C. and the melting point was 255 ° C.

(PET-I)
A polyester resin (inherent viscosity 0.65) having a terephthalic acid component of 88 mol% as a dicarboxylic acid component, 12 mol% of an isophthalic acid component, and 100 mol% of an ethylene glycol component as a glycol component, has a number average particle size of 0.2 μm. Polyester resin obtained by compounding the aggregated silica of 0.5% by mass with respect to 100% by mass in total of the polyethylene terephthalate resin. The glass transition temperature was 77 ° C. and the melting point was 230 ° C.

(PP)
“Noblen R101” manufactured by Sumitomo Chemical Co., Ltd. (polyolefin resin having an MFR of 19 g / 10 min and a melting point of 160 ° C. according to JIS K7210-1999)
(Ny)
"Amilan CM6241M" manufactured by Toray (polyamide resin)
Example 1
“PET” was supplied to a vented co-axial twin screw extruder with an oxygen concentration of 0.2% by volume, the extruder cylinder temperature was melted at 270 ° C., the short tube temperature was 275 ° C., the die temperature was 280 ° C., T The sheet was discharged from a die onto a cooling drum whose temperature was controlled at 50 ° C. Then, as the MD1 step, the stretching section between the low-speed roll group and the high-speed roll group is surrounded by a heat insulating material and set to 100 ° C. with hot air heating, and the stretching in this section is stretched 1.6 times in the longitudinal direction. A film sample was obtained.

(Examples 2 to 4)
A film sample was obtained in the same manner as in Example 1 except that various conditions were as shown in Table 1.

(Example 5)
Various conditions are as shown in Table 1. Before the MD1 step, the tenter method is uniaxially stretched in the width direction (hot air oven heating, 85 ° C, 3.6 times) (TD0 step), and the heating temperature is 120 ° C (pressurized water) A film was obtained in the same manner as in Example 1 except that steam was used as the heat medium. Then, both ends were slit with the same length, and the rest was used as a film sample.

(Example 6)
A film sample was obtained in the same manner as in Example 5 except that the magnification of the TD0 step was 3.8 times.

(Examples 7 to 10)
Various conditions were as shown in Table 2, and a film was obtained in the same manner as in Example 1 except that the MD1 step was roll stretching by 98 ° C. roll heating (water was used as a heat medium). In Examples 9 and 10, after obtaining the film after the MD1 step, both ends were slit with the same length, and the remainder was used as a film sample.

(Examples 11 and 12)
Various conditions are as shown in Table 3. Before the MD1 step, the tenter method is uniaxially stretched in the width direction (hot air oven heating, 85 ° C, 3.0 times) (TD0 step), and the roll heating temperature is 120 ° C ( A film was obtained in the same manner as in Example 7 except that pressurized steam was used as the heating medium. In addition, after obtaining the film after MD1 process, both ends were slit by the same length, respectively, and the remainder was made into the film sample.

(Example 13)
Various conditions are as shown in Table 3, and after MD1 step, it was the same as Example 7 except that uniaxial stretching (hot air oven heating, 120 ° C., 1.8 times) was performed in the width direction by the tenter method (TD2 step). A film was obtained. In addition, after obtaining the film after TD2 process, both ends were each slitted by the same length, and the remainder was made into the film sample.

(Example 14)
Various conditions are as shown in Table 3. Before the MD1 step, the tenter method is uniaxially stretched in the width direction (hot air oven heating, 85 ° C, 3.0 times) (TD0 step), and the tenter method is uniaxially in the width direction. A film was obtained in the same manner as in Example 7 except that stretching (hot air oven heating, 150 ° C., 1.5 times) was performed (step TD2). In addition, after obtaining the film after TD2 process, both ends were each slitted by the same length, and the remainder was made into the film sample.

(Examples 15 to 17)
The main constituent resin of the film was changed from “PET” as shown in Tables 3 and 4 and various conditions were changed as shown in Tables 3 and 4 to obtain a film in the same manner as in Example 1. .

(Example 18)
When various conditions are as shown in Table 4 and the base temperature is set to four temperature control sections with a uniform length in the width direction, a total of two locations at both ends are 300 ° C. and two locations at the center are 280 ° C. A film was obtained in the same manner as in Example 7 except that.
(Example 19)
Various conditions are as shown in Table 5, and the film before the MD1 step is heated to a room temperature after heating a range of 200 mm from both ends until the film temperature reaches 85 ° C. using an infrared (IR) heater. After cooling to air, a film was obtained in the same manner as in Example 7 except that the MD1 step was performed.

(Comparative Examples 1-3)
A film was obtained in the same manner as in Example 1 except that various conditions were as shown in Table 5. In addition, about the comparative examples 2 and 3, after obtaining the film after MD1 process, both ends were slit by the same length, respectively, and the remainder was made into the film sample.

(Comparative Example 4)
A film sample was obtained in the same manner as in Example 6 except that various conditions were as shown in Table 5 and the magnification in the TD0 step was 4.8 times.

The heat-shrinkable film production method of the present invention can obtain a film having uniform shrinkage at the center and end in the width direction even when a wide sample of 1000 mm or more is used. A heat-shrinkable film having uniform shrinkage characteristics can be produced.

Claims (6)

A method for producing a heat-shrinkable film having a film width W (mm) of 1000 mm or more, comprising a step (MD1) of stretching in the longitudinal direction, and a film width W1 (mm) before MD1 and a film width after MD1 A method for producing a heat-shrinkable film, wherein W2 (mm) satisfies the following formula (I), and the W2 (mm) and MD1 draw ratio (times) satisfy the formula (II).
0.8 ≦ (W2) / (W1) <1 (I)
400 ≦ (W2) / (MD1 draw ratio) ≦ 6000 (II) The manufacturing method of the heat-shrinkable film of Claim 1 whose process (MD1) extended | stretched to a longitudinal direction is a roll heating system. The average value TE1 (μm) of the thickness at both ends of the width direction position of the film before the step (MD1) of stretching in the longitudinal direction and the thickness TC1 (μm) of the center satisfy the following formula (III). Or the manufacturing method of the heat-shrinkable film of 2.
1.2 ≦ (TE1) / (TC1) ≦ 50 (III) The average value TE2 (μm) of the thickness at both ends of the film in the width direction after the step of stretching in the longitudinal direction (MD1) and the thickness TC2 (μm) at the center satisfy the following formula (IV): The manufacturing method of the heat-shrinkable film in any one of 1-3.
1.2 ≦ (TE2) / (TC2) ≦ 50 (IV) The manufacturing method of the heat-shrinkable film in any one of Claims 1-4 with which TE1 (micrometer), TC1 (micrometer), TE2 (micrometer), and TC2 (micrometer) satisfy the following (V) formula.
0.9 ≦ {(TE2) / (TC2)} / {(TE1) / (TC1)} ≦ 2 (V) The method for producing a heat-shrinkable film according to any one of claims 1 to 5, wherein the heat-shrinkable film comprises a polyester resin as a main constituent.