JPWO2016189987A1 - Wrap film - Google Patents

Abstract

The following formula (1): Δn = nx−ny = Re / d (1) (where nx represents the refractive index in the slow axis direction in the film plane, and ny represents the slow axis direction in the film plane) The refractive index in the vertical direction is represented, Re represents the in-plane retardation (unit: nm) of the film, d represents the thickness (unit: nm) of the film, and the birefringence Δn determined by the following formula (1a) : 0.0003 ≦ Δn ≦ 0.0013 The condition represented by (1a) is satisfied, and the following formula (2): ΔP = (nx + ny) / 2−nz (2) (wherein nx is a delay in the film plane) The refractive index in the phase axis direction, ny represents the refractive index in the direction perpendicular to the slow axis direction in the film plane, and nz represents the refractive index in the thickness direction of the film). Is represented by the following formula (2a): −0.0120 ≦ ΔP ≦ −0.0102 (2a) Wrap film and satisfies the conditions.

Description

  The present invention relates to a wrap film, and more particularly to a wrap film containing a polyvinylidene chloride resin.

  A film made of polyvinylidene chloride resin (hereinafter abbreviated as “PVDC resin”) has excellent properties such as adhesion to containers, transparency, barrier properties, heat resistance, and fragrance retention properties. It is known that it is a suitable film (for example, Unexamined-Japanese-Patent No. 2011-168750 (patent document 1)). Such a PVDC resin wrap film is wound around a core material and loaded into a dedicated carton as a wrap film wound body. Then, when used, a wrap film having a required length is pulled out of the carton and cut with a saw blade mounted on the carton.

JP 2011-168750 A

  However, when the wrap film made of PVDC resin is pulled out of the carton and cut with a saw blade attached to the carton, the wrap film may be broken in the vertical direction or the saw blade may be deteriorated. Then, when the cause of these malfunctions was examined, the present inventors found out that the strong force applied when cutting a wrap film was the cause.

  This invention is made | formed in view of the subject which the said prior art has, and aims at providing the wrap film made from a PVDC resin which can be easily cut with weak force.

  As a result of intensive studies to achieve the above object, the present inventors have found that a wrap film made of PVDC resin satisfying predetermined conditions of birefringence and plane orientation can be cut with a weak force, and the present invention has been completed. It came to do.

That is, the wrap film of the present invention is a wrap film containing a polyvinylidene chloride resin,
Following formula (1):
Δn = n _x −n _y = Re / d (1)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, Re is the plane of the film retardation (Unit: nm), d represents the thickness of the film (unit: nm))
The birefringence Δn determined by the following formula (1a):
0.0003 ≦ Δn ≦ 0.0013 (1a)
Meets the conditions
Following formula (2):
_{ΔP = (n x + n y} ) / 2-n z (2)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, the thickness of the n _z is the film Represents the refractive index in the direction)
The plane orientation degree ΔP obtained by the following formula (2a):
−0.0120 ≦ ΔP ≦ −0.0102 (2a)
It satisfies the condition represented by

  The thickness of the wrap film of the present invention is preferably 5 to 15 μm. The polyvinylidene chloride resin is preferably a copolymer of vinylidene chloride and a comonomer copolymerizable with the vinylidene chloride, and the comonomer is preferably vinyl chloride. Furthermore, the slow axis direction in the film plane is preferably the longitudinal direction (MD) of the wrap film. In addition, the machine direction (MD) is the flow direction of the film at the time of inflation biaxial stretching.

  Such a wrap film of the present invention is used in the state of a wrap film wound body in which the longitudinal direction (MD) is a winding direction and is loaded in a carton equipped with a saw blade.

  According to the present invention, it is possible to obtain a PVDC resin wrap film that can be easily cut with a weak force.

It is the schematic which shows the wrap film manufacturing apparatus used by the Example and the comparative example. It is a graph which shows the result of having plotted birefringence degree (DELTA) n with respect to plane orientation degree (DELTA) P about the wrap film obtained by the Example and the comparative example.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  The wrap film of the present invention will be described. The wrap film of the present invention is a wrap film containing a polyvinylidene chloride resin (PVDC resin). The PVDC resin used in the present invention is a copolymer of vinylidene chloride (VD) and a comonomer copolymerizable with vinylidene chloride. The content of vinylidene chloride in the PVDC resin is preferably 60 to 98% by mass, more preferably 65 to 97% by mass, still more preferably 70 to 95%, particularly preferably 75 to 90% by mass, and a comonomer. As content, 2-40 mass% is preferable, 3-35 mass% is more preferable, 5-30 mass% is still more preferable, 10-25 mass% is especially preferable. If the comonomer content is less than the lower limit, the internal plasticization of the PVDC resin becomes insufficient and the melt processability tends to decrease. On the other hand, if the upper limit is exceeded, the gas barrier property and the water vapor barrier property tend to decrease. It is in.

  Examples of the comonomer include vinyl chloride (VC); alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, and the like. 18); methacrylic acid alkyl esters (alkyl group having 1 to 18 carbon atoms) such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate; acrylonitrile, methacrylonitrile Vinyl cyanide such as styrene; aromatic vinyl such as styrene; vinyl ester of aliphatic carboxylic acid (carbon number 1 to 18) such as vinyl acetate; alkyl vinyl ether (alkyl group having 1 to 18 carbon atoms); acrylic acid, methacrylic acid , Malein Vinyl polymerizable unsaturated carboxylic acids such as fumaric acid and itaconic acid; alkyl esters (including partial esters) of vinyl polymerizable unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. ); Epoxy group-containing vinyl polymerizable monomers such as glycidyl acrylate and glycidyl methacrylate; diene monomers such as butadiene and isoprene; chlorinated diene monomers such as chloroprene; divinylbenzene, ethylene glycol diacrylate, ethylene glycol methacrylate, etc. Examples thereof include polyfunctional monomers having two or more polymerizable double bonds in the molecule. These comonomers may be used individually by 1 type, or may use 2 or more types together. Among such comonomers, vinyl chloride (VC), methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate are preferable, and vinyl chloride (VC) is more preferable.

  The reduced viscosity (η) (unit, L / g) of the PVDC resin is preferably 0.030 to 0.070 from the viewpoints of melt processability, stretch processability, packaging machine suitability, and cold resistance, and 0.033. -0.065 is more preferable, and 0.035-0.060 L / g is particularly preferable. When the reduced viscosity of the PVDC resin is less than the lower limit, the stretch processability tends to decrease, or the strength and cutability of the film tend to decrease. On the other hand, when the upper limit is exceeded, the melt processability decreases or coloring There is a tendency to do. In the PVDC resin used in the present invention, two or more kinds of PVDC resins having different reduced viscosities may be mixed to adjust the reduced viscosity to the above range.

  Such a PVDC resin can be synthesized by a known method such as suspension polymerization, emulsion polymerization, solution polymerization or the like, but a powder resin having an average particle size of 40 to 600 μm can be obtained without being pulverized. From this viewpoint, suspension polymerization is preferable.

  In the present invention, the PVDC resin may be used alone, or the PVDC resin may be added to a plasticizer, a heat stabilizer, an antioxidant, a lubricant, a dispersion aid, a filler, an ultraviolet absorber, an interface. Various additives such as an activator and a pH adjuster may be added and used as a PVDC resin composition. The PVDC resin composition containing the additive can be prepared by adding the additive to the polymerization reaction system at any time before, during, or after the synthesis of the PVDC resin.

  Examples of the plasticizer include dioctyl phthalate, acetyl tributyl citrate, dibutyl sebacate, dioctyl sebacate, acetylated monoglyceride, acetylated diglyceride, acetylated triglyceride, polycondensate of adipic acid and 1,3-butanediol, adipic acid And a 1,4-butanediol polycondensate. These plasticizers may be used alone or in combination of two or more. As addition amount of a plasticizer, 0.05-10 mass parts is preferable with respect to 100 mass parts of PVDC resin, 0.1-5 mass parts is more preferable, 0.5-3 mass parts is especially preferable.

  Examples of heat stabilizers include epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil, epoxidized animal oils, epoxidized fatty acid esters such as epoxidized octyl stearate, and epoxidized resin prepolymers such as bisphenol A glycidyl ether. Epoxy compounds; epoxy group-containing resins such as glycidyl group-containing acrylic resins and glycidyl group-containing methacrylic resins can be mentioned. These heat stabilizers may be used alone or in combination of two or more. As addition amount of a heat stabilizer, 0.1-5 mass parts is preferable with respect to 100 mass parts of PVDC resin, 0.5-4 mass parts is more preferable, and 1-3 mass parts is especially preferable.

  Examples of the antioxidant, the lubricant, the dispersion aid, the filler, the ultraviolet absorber, the surfactant, and the pH adjuster include those described in JP2011-94035A.

  Moreover, in this invention, you may mix other resin with the said PVDC resin. The mixing amount of the other resin is preferably 30 parts by mass or less with respect to 100 parts by mass of the PVDC resin, more preferably 20 parts by mass or less, particularly preferably 10 parts by mass or less from the viewpoint of compatibility with the PVDC resin. preferable. The content of the vinylidene chloride component in the mixed resin of the PVDC resin and the other resin is preferably 50% by mass or more, and 60% by mass or more from the viewpoints of gas barrier property, water vapor barrier property, and heat resistance. Is more preferable, and 70 mass% or more is particularly preferable.

  Examples of the other resin include ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid ester copolymer (preferably , Ethylene-acrylic acid alkyl ester copolymer (alkyl group having 1 to 18 carbon atoms)), ethylene-methacrylic acid ester copolymer (preferably ethylene-methacrylic acid alkyl ester copolymer (alkyl group having 1 carbon atom) To 18)), homopolymers of ethylene-glycidyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, acrylic ester (preferably alkyl ester of acrylic acid (C1-C18 of alkyl group)) and Copolymer (eg, methyl acrylate-butyl acrylate copolymer), Homopolymers and copolymers (e.g., methyl methacrylate-butyl methacrylate copolymer) and ethylene ionomers of uric acid esters (preferably alkyl methacrylates (alkyl group having 1 to 18 carbon atoms)) , Methyl methacrylate-butadiene-styrene copolymer, polyamide and the like. These other resins may be used alone or in combination of two or more.

The wrap film of the present invention is formed by melt-extruding the PVDC resin or the PVDC resin composition using, for example, an extruder to form a film, cooling, stretching (preferably biaxial stretching), and further relaxation. It can manufacture by giving a process, It is preferable to manufacture especially by the inflation biaxial stretching method by a circular die. At this time, the birefringence Δn of the resulting wrap film is expressed by the following formula (1a):
0.0003 ≦ Δn ≦ 0.0013 (1a)
The degree of plane orientation ΔP satisfies the following condition (2a):
−0.0120 ≦ ΔP ≦ −0.0102 (2a)
The cooling temperature, stretching temperature, stretching ratio, relaxation temperature, and relaxation rate of the melt-extruded film are adjusted so as to satisfy the condition represented by If the birefringence Δn is less than 0.0003, or the plane orientation ΔP is less than −0.0120, rupture during inflation biaxial stretching tends to occur, and stable film formation becomes difficult. Moreover, when the birefringence Δn exceeds 0.0013 or the plane orientation ΔP exceeds −0.0102, the wrap film is easily stretched, and it is difficult to easily cut the wrap film with a weak force. . From such a viewpoint, the birefringence Δn is expressed by the following formula (1b):
0.0005 ≦ Δn ≦ 0.0013 (1b)
The plane orientation degree ΔP is preferably the following formula (2b):
−0.0115 ≦ ΔP ≦ −0.0102 (2b)
It is preferable that the condition represented by

The birefringence Δn is expressed by the following formula (1):
Δn = n _x −n _y = Re / d (1)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, Re is the plane of the film retardation (Unit: nm), d represents the thickness of the film (unit: nm))
The degree of plane orientation ΔP is calculated by the following formula (2):
_{ΔP = (n x + n y} ) / 2-n z (2)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, the thickness of the n _z is the film Represents the refractive index in the direction)
Is required.

  The birefringence Δn tends to decrease as the stretching ratio (molecular orientation) in the machine direction (MD) increases or as the relaxation rate in the machine direction (MD) decreases. Since the orientation degree ΔP tends to decrease as the draw ratio increases or the relaxation rate decreases, the birefringence degree Δn is controlled by controlling the stretch ratio and relaxation rate based on these tendencies. And the plane orientation degree ΔP can be adjusted within the above range.

  Although the cooling temperature of the film after melt extrusion cannot be determined unconditionally, it is preferably 20 ° C. or less, and more preferably 15 ° C. or less. If the cooling temperature exceeds the upper limit, crystallization of the resin proceeds and the stretchability tends to deteriorate, and the wrap film tends to whiten and the transparency tends to be impaired. In addition, although there is no restriction | limiting in particular as a minimum of the said cooling temperature, 3 degreeC or more is preferable and 5 degreeC or more is more preferable from a viewpoint of economical efficiency (specifically cooling capability).

  The stretching temperature cannot be determined unconditionally, but is preferably 15 ° C. or higher, and more preferably 20 ° C. or higher. When the stretching temperature is less than the lower limit, the stretchability is deteriorated and the inflation bubbles tend to burst. In addition, although there is no restriction | limiting in particular as an upper limit of the said extending | stretching temperature, From a viewpoint of workability | operativity or economical efficiency (enlargement of an installation), 50 degrees C or less is preferable and 45 degrees C or less is more preferable.

  Although the stretching ratio cannot be determined unconditionally, for example, the stretching ratio in the machine direction (MD) is preferably 3.6 to 5.0 times, and more preferably 3.8 to 4.6 times. When the stretching ratio in the machine direction (MD) is less than the lower limit, inflation bubbles tend to be loosened, making continuous film formation difficult. On the other hand, when the upper limit is exceeded, an air bag is generated and the bubble shape becomes unstable. , Tend to cause uneven width and uneven thickness. Moreover, as a draw ratio of a horizontal direction (TD), 4.0-5.5 times are preferable and 4.5-5.1 times are more preferable. When the stretching ratio in the transverse direction (TD) is less than the lower limit, the bubble shape becomes unstable and tends to cause unevenness in width and thickness. On the other hand, when it exceeds the upper limit, it tends to easily burst.

  The relaxation temperature cannot be generally determined, but is preferably 20 to 100 ° C, and more preferably 25 to 85 ° C. When the relaxation temperature is less than the lower limit, a sufficient relaxation rate cannot be obtained, winding tightening tends to occur, and problems such as deformation of the core portion tend to occur. On the other hand, when the upper limit is exceeded, the transparency of the film Tend to be damaged.

  Although the relaxation rate cannot be determined unconditionally, for example, the relaxation rate in the machine direction (MD) is preferably 4.5 to 12.0%, and more preferably 5.0 to 11.0%. When the relaxation rate in the machine direction (MD) is less than the lower limit, the relaxation is insufficient, and when creating a wrap film wound body, there is a tendency for tightening to occur over time, whereas, when the upper limit is exceeded, The film is slack and tends to wrinkle during winding. Moreover, as a relaxation rate of a horizontal direction (TD), 2.5 to 6.5% is preferable and 3.0 to 6.1% is more preferable. When the transverse direction (TD) relaxation rate is less than the lower limit, the film width tends to change after the wrap film is wound. On the other hand, when the upper limit is exceeded, wrinkles occur during winding. It tends to be easy.

  The thickness of the wrap film thus obtained is preferably 5 to 15 μm. When the thickness of the wrap film is less than the lower limit, sufficient strength cannot be obtained, and it tends to be broken during use.On the other hand, when the upper limit is exceeded, a large force tends to be required when cutting, and , Rigidity increases and practical adhesion tends to deteriorate.

  Moreover, in the wrap film of this invention, it is preferable that the slow axis direction in a film surface is the vertical direction (MD) of a wrap film. Furthermore, the wrap film of the present invention is preferably obtained as a wound body in which the longitudinal direction (MD) of inflation biaxial stretching is the winding direction. By these, since the longitudinal direction of the wrap film coincides with the longitudinal direction (MD) of inflation biaxial stretching, it becomes possible to easily cut with a weak force.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In addition, the reduced viscosity of the polyvinylidene chloride resin, the birefringence degree and the plane orientation degree of the wrap film were measured by the following methods.

(1) Reduced viscosity 1 g of polyvinylidene chloride resin was added to 50 ml of tetrahydrofuran and dissolved by heating to 40 ° C. This solution was added to methanol to precipitate a polyvinylidene chloride resin, recovered by filtration, and then dried. 80 mg of polyvinylidene chloride resin after drying was weighed, 20 ml of cyclohexanone at 30 ° C. was added as a solvent, and dissolved by heating at 70 ° C. for 60 minutes. Then, it cooled at room temperature and filtered and obtained the sample solution.

After injecting 5 ml of this sample solution into an Ubbelohde viscometer and allowing to stand for 5 minutes in a thermostatic bath at 30 ° C., the number of seconds of flow of the sample solution was measured by a conventional method, and the following formula:
η = (1/4) × {(t ₂ / t ₁ ) −1}
(In the formula, t ₁ represents the flow down time (unit: second) of cyclohexanone (solvent) at 30 ° C., and t ₂ represents the flow down time (unit: second) of the sample solution at 30 ° C.)
Was used to determine the reduced viscosity (η).

(2) Birefringence degree A wrap film is attached to a phase difference measuring device (“KOBRA-WR” manufactured by Oji Scientific Instruments) so that the longitudinal direction (MD) of the film is 0 ° of the measuring device, The in-plane retardation Re of the wrap film at a wavelength of 589 nm was measured, and the following formula (1):
Δn = n _x −n _y = Re / d (1)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, Re is the plane of the film retardation (Unit: nm), d represents the thickness of the film (unit: nm))
Was used to determine the birefringence Δn of the wrap film. This measurement was performed on five randomly selected measurement points, and the average value was obtained. In addition, this average value was calculated | required as a value of 4 decimal places by rounding off the 5 decimal places. The orientation angle display range was set to -90 degrees to 90 degrees. Accordingly, when the orientation angle is in the range of −45 ° to 45 °, polyvinylidene chloride has negative intrinsic birefringence, which means that the slow axis direction of the wrap film is the machine direction (MD). . That is, it means that the orientation in the transverse direction (TD) of the wrap film is stronger than that in the longitudinal direction (MD), and that the orientation in the longitudinal direction (MD) becomes stronger as Δn becomes smaller.

(3) Degree of plane orientation A wrap film is attached to a phase difference measuring device (“KOBRA-WR” manufactured by Oji Scientific Instruments Co., Ltd.) so that the longitudinal direction (MD) of the film is the 0 ° direction of the measuring device, is inclined film so that the incident angle becomes 40 ° tilt central axis as the fast axis, the slow axis direction of the refractive indices n _x in the plane of the wrapping film at a wavelength of 589 _nm, the slow axis direction in a plane The refractive index n _{y in the} vertical direction and the refractive index _nz in the thickness direction were measured in the low phase difference mode with an average refractive index Nave = 1.609, and the following formula (2):
_{ΔP = (n x + n y} ) / 2-n z (2)
Thus, the plane orientation degree ΔP of the wrap film was obtained. This measurement was performed on five randomly selected measurement points, and the average value was obtained. In addition, this average value was calculated | required as a value of 4 decimal places by rounding off the 5 decimal places.

(Preparation Example 1)
Vinylidene chloride (VD) and vinyl chloride (VC) are mixed at VD: VC = 82: 18 (mass ratio), and vinylidene chloride-vinyl chloride copolymer (PVDC resin, reduced viscosity ( η): 0.044 L / g) was synthesized. To 100 parts by mass of this PVDC resin, as additives, acetyl tributyl citrate (ATBC), diacetylated monoglyceride (DALG), epoxidized soybean oil and liquid paraffin are added and mixed to a total of 8.4 parts by mass. A PVDC resin composition was prepared.

Example 1
The wrap film was produced using the manufacturing apparatus shown in FIG. That is, after the PVDC resin composition obtained in Preparation Example 1 was melt-extruded from a circular die at 175 ° C. using a single-screw extruder 1 having a diameter of 75 cm, the obtained tubular parison was cooled to a 10 ° C. cooling bath (1 The bath was quenched with 2 and then passed through a warm water bath (2 baths) 3 at 40 ° C. Thereafter, air is pressed into the tubular parison between the pinch rollers 4 and 5 having different rotational speeds to expand, and the stretching temperature is 25 ° C., the longitudinal direction (MD) is 4.2 times, and the transverse direction (TD) is 5.1 times. Inflation biaxial stretching is performed at a stretching ratio of 25 ° C., and the relaxation temperature is 25 ° C., the longitudinal direction (MD) is 10.1%, and the lateral direction (TD) is 4.0% between the pinch rollers 5 and 6 having different rotational speeds. After performing the relaxation treatment with the relaxation rate, the film was wound up with the winding roller 7 and then rolled back with a slit to obtain a 20-m roll wrap film roll (width 30 cm). The stretching temperature is the temperature of the atmosphere in which the tubular parison taken out from the two baths is exposed during biaxial stretching (that is, the environmental temperature in the region between the pinch rollers 4 and 5), and the relaxation temperature is The temperature of the atmosphere to which the film after biaxial stretching is exposed during the relaxation treatment (that is, the environmental temperature in the region between the pinch rollers 5 and 6). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 2)
Stretching temperature 25 ° C, longitudinal direction (MD) 4.4 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 5.0 times, relaxation temperature 25 ° C, longitudinal direction (MD) 10.1%, A wrapped wrap film was produced in the same manner as in Example 1 except that the relaxation treatment was performed at a relaxation rate of 4.8% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 3)
Stretching temperature 25 ° C, longitudinal direction (MD) 4.6 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 4.7 times, relaxation temperature 25 ° C, longitudinal direction (MD) 5.0%, A wrapped wrap film was produced in the same manner as in Example 1 except that the relaxation treatment was performed at a relaxation rate of 5.1% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

Example 4
4. Change the temperature of the cooling bath (1 bath) to 11 ° C and the temperature of the hot water bath (2 baths) to 45 ° C, stretching temperature 25 ° C, longitudinal direction (MD) 4.0 times, transverse direction (TD) 5. Example in which inflation biaxial stretching was performed at a stretching ratio of 1 ×, and relaxation treatment was performed at a relaxation temperature of 25 ° C., a relaxation rate of 5.0% in the machine direction (MD), and 5.3% in the transverse direction (TD). A wrap film wound body was produced in the same manner as in Example 1. About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 5)
Stretch temperature 25 ° C, longitudinal direction (MD) 4.5 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 4.8 times, relaxation temperature 25 ° C, longitudinal direction (MD) 5.0%, A wrapped wrap film was produced in the same manner as in Example 4 except that the relaxation treatment was performed at a relaxation rate of 4.0% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 6)
The temperature of the hot water bath (2 baths) is changed to 30 ° C., inflation biaxial stretching is performed at a stretching temperature of 30 ° C., a stretching ratio of machine direction (MD) of 4.2 times, and transverse direction (TD) of 4.6 times. A wrapped wrap film was produced in the same manner as in Example 4 except that the relaxation treatment was performed at a relaxation temperature of 40 ° C., a relaxation rate of 10.8% in the machine direction (MD), and 4.2% in the transverse direction (TD). . About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 7)
Stretching temperature 30 ° C, longitudinal direction (MD) 4.1 times, transverse direction (TD) inflation biaxial stretching at a stretching ratio of 4.8 times, relaxation temperature 40 ° C, longitudinal direction (MD) 10.7%, A wrapped wrap film was produced in the same manner as in Example 6 except that the relaxation treatment was performed at a relaxation rate of 6.1% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Example 8)
Stretching temperature 30 ° C, longitudinal direction (MD) 4.3 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 4.5 times, relaxation temperature 40 ° C, longitudinal direction (MD) 10.7%, A wrapped wrap film was produced in the same manner as in Example 6 except that the relaxation treatment was performed at a relaxation rate of 4.3% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 1)
Stretching temperature 25 ° C, longitudinal direction (MD) 3.2 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 5.4 times, relaxation temperature 25 ° C, longitudinal direction (MD) 10.1%, A wrapped wrap film was produced in the same manner as in Example 1 except that the relaxation treatment was performed at a relaxation rate of 4.9% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 2)
Stretching temperature 25 ° C, longitudinal direction (MD) 3.4 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 3.3 times, relaxation temperature 25 ° C, longitudinal direction (MD) 10.1%, A wrapped wrap film was produced in the same manner as in Example 1 except that the relaxation treatment was performed at a relaxation rate of 3.5% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 3)
Stretching temperature is 25 ° C, longitudinal direction (MD) is 3.4 times, transverse direction (TD) is inflation biaxial stretching at a stretching ratio of 4.4 times, relaxation temperature is 25 ° C, longitudinal direction (MD) is 10.1%, A wrapped wrap film was produced in the same manner as in Example 1 except that the relaxation treatment was performed at a relaxation rate of 3.5% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 4)
4. Change the temperature of the cooling bath (1 bath) to 12 ° C and the temperature of the hot water bath (2 baths) to 30 ° C, stretching temperature 25 ° C, machine direction (MD) 4.0 times, transverse direction (TD) 5. Example in which inflation biaxial stretching was performed at a stretching ratio of 1 ×, and relaxation treatment was performed at a relaxation temperature of 25 ° C., a relaxation rate of 10.1% in the machine direction (MD), and 3.9% in the transverse direction (TD). A wrap film wound body was produced in the same manner as in Example 1. About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 5)
Stretching temperature 25 ° C, longitudinal direction (MD) 3.5 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 5.3 times, relaxation temperature 25 ° C, longitudinal direction (MD) 5.0%, A wrapped wrap film was produced in the same manner as in Example 4 except that the relaxation treatment was performed at a relaxation rate of 5.2% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 6)
Stretch temperature 25 ° C, longitudinal direction (MD) 4.0 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 4.7 times, relaxation temperature 25 ° C, longitudinal direction (MD) 5.0%, A wrapped wrap film was produced in the same manner as in Example 4 except that the relaxation treatment was performed at a relaxation rate of 5.8% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 7)
Stretching temperature is 30 ° C, longitudinal direction (MD) is 4.0 times, transverse direction (TD) is inflation biaxial stretching at a stretching ratio of 4.7 times, relaxation temperature is 40 ° C, longitudinal direction (MD) is 10.8%, A wrapped wrap film was produced in the same manner as in Example 6 except that the relaxation treatment was performed at a relaxation rate of 4.2% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

(Comparative Example 8)
Stretching temperature 30 ° C, longitudinal direction (MD) 4.0 times, transverse direction (TD) inflation biaxial stretching at a draw ratio of 4.7 times, relaxation temperature 40 ° C, longitudinal direction (MD) 10.7%, A wrapped wrap film was produced in the same manner as in Example 6 except that the relaxation treatment was performed at a relaxation rate of 4.6% in the transverse direction (TD). About the obtained wrap film, thickness was measured and birefringence degree (DELTA) n (average value) and plane orientation degree (DELTA) P (average value) were calculated | required. The results are shown in Table 1. Moreover, the orientation angle of the obtained wrap film was in the range of -45 degrees to 45 degrees. From this, it was found that the slow axis direction of the obtained wrap film was the machine direction (MD), and the orientation in the transverse direction (TD) was stronger than that in the machine direction (MD).

<Cutability (Sensory test)>
The wrapping film rolls obtained in the examples and comparative examples were loaded into a commercially available new NEW Kurelap (registered trademark) carton (for 30 cm width) equipped with a saw blade made of resin. Pull the wrap film about 30cm out of the carton, securely close the carton lid, hold the carton so that the thumb is in place, rotate the carton inward and pull the wrap film from the center to the lateral (TD) outside Cut towards. The wrap film was cut on 10 monitors and judged according to the following criteria. The results are shown in Table 1.
A: Easy to cut with weak force.
B: Can be cut with a weak force, but difficult to cut.
C: Those that cannot be cut with a weak force and require a relatively strong force.

<Cutability (cut test)>
The wrap films obtained in the examples and comparative examples were cut to 40 mm in the transverse direction (TD) and 140 mm in the longitudinal direction (MD) to prepare test wrap films. One end of the longitudinal direction (MD) of the test wrap film is fixed with a tape inside a commercially available new cle wrap (registered trademark) carton (for 30 cm width) equipped with a plastic saw blade. Attached to. In that case, it fixed so that the center part of the test wrap film which protrudes from the carton might contact the V-shaped front-end | tip of a saw blade of a carton. Next, the other end of the test wrap film in the machine direction (MD) is sandwiched between chuck portions of a Tensilon universal material testing machine ("RTC-210A" manufactured by Orientec Co., Ltd.), and a saw blade and a test wrap film The angle of the jig was adjusted so that the angle was 80 °. Thereafter, the test wrap film was pulled upward at a pulling speed of 1000 mm / min, and the strength (peak value (unit: N)) when the wrap film was cut was measured, and the wrap film obtained in Example 1 was measured. The cutting force was divided by the cutting force of the wrap film obtained in each example, and the relative score based on the cutting force of the wrap film obtained in Example 1 was obtained. The results are shown in Table 1. Note that a wrap film having a relative score of 1.00 or more means a wrap film that can be easily cut with a weak force equal to or less than that of the wrap film obtained in Example 1, while the relative score is 1. A wrap film of less than 00 means that the wrap film requires a stronger force than the wrap film obtained in Example 1 and is difficult to cut.

  When comparing the plane orientation degree ΔP and the birefringence degree Δn of Example 7 and Comparative Example 4 shown in Table 1, ΔP is equivalent, but Δn is smaller in Example 7, so that the longitudinal direction (MD) This suggests that the molecular orientation is large. Since the cutability of the wrap film of the present invention is evaluated for ease of breaking when the film is pulled in a direction perpendicular to the saw blade, the tensile direction (longitudinal direction of the wrap film) and inflation biaxial stretching It is considered that Example 7 having a larger molecular orientation in the vertical direction (MD) was more likely to break when the vertical direction (MD) was matched. On the other hand, although Δn of Comparative Example 6 is smaller than that of Example 7, ΔP is large, so it is considered that it was difficult to break.

  Based on the results shown in Table 1, the degree of plane orientation ΔP was plotted against the degree of birefringence Δn. The result is shown in FIG.

As is clear from the results shown in Table 1 and FIG. 2, the birefringence Δn is expressed by the following formula (1a):
0.0003 ≦ Δn ≦ 0.0013 (1a)
The degree of plane orientation ΔP satisfies the following condition (2a):
−0.0120 ≦ ΔP ≦ −0.0102 (2a)
The wrap films satisfying the conditions represented by (Examples 1 to 8, in the dotted frame in FIG. 2) can be easily cut with a weak force, and the wrap films obtained in Examples 2 to 8 are examples. The relative score for the wrap film obtained in 1 was 1.00 or more.

  On the other hand, a wrap film (Comparative Examples 1, 4 to 5) in which the birefringence Δn does not satisfy the condition represented by the formula (1a) and the plane orientation degree ΔP do not satisfy the condition represented by the formula (2a). The wrap films (Comparative Examples 1 to 3, 5 to 8) were difficult to cut or could not be cut with a weak force, and the relative score with respect to the wrap film obtained in Example 1 was less than 1.00. In particular, the wrap films (Comparative Examples 1 to 3) having a degree of plane orientation ΔP of −0.0093 or more cannot be cut with a weak force, and a strong force is required, which is relative to the wrap film obtained in Example 1. The relative score was 0.68 or less.

  As described above, according to the present invention, a PVDC resin wrap film that can be easily cut with a weak force can be obtained.

  Therefore, since the wrap film of the present invention is difficult to tear in the vertical direction and can suppress the deterioration of the saw blade of the carton, it is useful as a wrap film for various packaging such as a home wrap film.

1: Extruder 2: Cooling bath 3: Hot water bath 4-6: Pinch roller 7: Winding roller

Claims (6)

A wrap film containing a polyvinylidene chloride resin,
Following formula (1):
Δn = n _x −n _y = Re / d (1)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, Re is the plane of the film retardation (Unit: nm), d represents the thickness of the film (unit: nm))
The birefringence Δn determined by the following formula (1a):
0.0003 ≦ Δn ≦ 0.0013 (1a)
Meets the conditions
Following formula (2):
_{ΔP = (n x + n y} ) / 2-n z (2)
(Wherein, n _x represents a refractive index in a slow axis direction in the film plane, n _y represents a refractive index in a direction perpendicular to the slow axis direction in the film plane, the thickness of the n _z is the film Represents the refractive index in the direction)
The plane orientation degree ΔP obtained by the following formula (2a):
−0.0120 ≦ ΔP ≦ −0.0102 (2a)
Wrapping film that satisfies the conditions   The wrap film of Claim 1 whose thickness is 5-15 micrometers.   The wrap film according to claim 1 or 2, wherein the polyvinylidene chloride-based resin is a copolymer of vinylidene chloride and a comonomer copolymerizable with the vinylidene chloride.   The wrap film according to claim 3, wherein the comonomer is vinyl chloride.   The wrap film as described in any one of Claims 1-4 whose slow axis direction in a film surface is the vertical direction (MD) of a wrap film.   It is a wound body which consists of a wrap film of Claim 5, Comprising: The longitudinal direction (MD) of this wrap film is a winding direction, The wrap film wound body currently loaded in the carton with which the saw blade was mounted | worn.