JP6561857B2 - Stretched film - Google Patents

Description

  The present invention relates to a stretched film excellent in moldability having good followability and / or stickability.

  Conventionally, films made of polypropylene resin have been widely used as packaging materials such as food packaging materials, industrial materials such as adhesive tapes and release papers, taking advantage of their rigidity, heat resistance, oil resistance, chemical resistance, processability, etc. It is used.

  A film made of such a polypropylene-based resin is the film alone, or the film is used as a decorative film or a protective film at the time of molding, the film and other films and sheets, metals such as aluminum foil, etc. In a state where the two are bonded together, they are molded into an arbitrary shape by thermoforming such as vacuum forming and pressure forming.

  As a film used in thermoforming, for example, Patent Document 1 describes a polypropylene resin sheet composed of a polypropylene resin and a filler. Patent Document 2 discloses a heat obtained from a resin composition comprising a polypropylene resin, two or more polyethylene resins having a specific melting point, and an amorphous polyolefin resin having a specific glass transition point. A polyolefin sheet for molding is described. The sheets described in Patent Documents 1 and 2 are both unstretched films. Although unstretched film is excellent in followability to curved surfaces and adherence to adherends, when heated at the time of molding, a film called drawdown causes a phenomenon of sagging and moldability May be bad.

  Patent Document 3 describes a sheet obtained by stretching a propylene resin composition containing a high melting point propylene resin, a low melting point propylene resin, an α-olefin comonomer and a nucleating component. However, the sheet described in Patent Document 3 does not have sufficient formability, and the followability may not be sufficient particularly when used for thermoforming in which a film such as deep drawing is greatly stretched.

JP 2001-131363 A Japanese Patent Laid-Open No. 9-118791 JP 2014-169446 A

  An object of the present invention is to provide a film that has good followability and / or stickability, isotropic properties, and excellent moldability.

  In order to solve the above-mentioned problems, the present inventors have repeatedly studied the stretched film in detail, and have completed the present invention.

That is, the present invention includes the following preferred embodiments.
[1] A stretched film including at least one layer containing, as a resin component, at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less. And the stretched film whose elongation of MD direction and elongation of TD direction of the said stretched film are both 150 to 850%.
[2] The stretched film according to [1], which is a multilayer film including at least one layer containing the polypropylene resin A and the soft resin B as resin components.
[3] The stretched film according to the above [1] or [2], containing 90 to 30% by mass of polypropylene resin A and 10 to 70% by mass of soft resin B based on the total amount of resin components.
[4] The heating elongation in the MD direction and the heating elongation in the TD direction measured at 120 ° C. by the TMA method are both −2 to 8%, according to any one of the above [1] to [3]. Stretched film.
[5] The stretched film according to any one of [1] to [4], wherein the ratio of the elongation in the TD direction to the elongation in the MD direction is 0.3 to 3.0.
[6] The stretched film according to any one of [1] to [5], wherein the tensile modulus in the MD direction and the tensile modulus in the TD direction are both 1.5 GPa or less.
[7] The stretched film according to any one of [1] to [6], wherein the polypropylene resin A includes homopolypropylene or a copolymer of propylene and ethylene.
[8] The stretched film according to any one of [1] to [7], wherein the MFR of the polypropylene resin A is 1 to 8 g / 10 min.
[9] The stretched film according to any one of [1] to [8], wherein the soft resin B has an MFR of 1 to 400 g / 10 min.

The stretched film of the present invention has good followability and / or stickability, isotropic properties, and excellent moldability.
In one embodiment of the present invention, the stretched film of the present invention has a small elongation during heating. For this reason, it is possible to suppress a decrease in formability due to drawdown particularly during thermoforming, and it is possible to suppress the occurrence of sagging or wrinkles due to printing when there is a printing process.

The present invention includes at least one layer containing, as a resin component, at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less. It is related with the stretched film whose elongation in a direction and elongation in a TD direction are both 150 to 850%. The stretched film of the present invention was formed from a resin composition containing at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less. It is a stretched film in which the MD direction elongation and the TD direction elongation are both 150 to 850%. That is, the layer containing at least one polypropylene resin A having a tensile elastic modulus of 1000 MPa or more and at least one soft resin B having a tensile elastic modulus of 200 MPa or less constituting the stretched film of the present invention as a resin component. From a resin composition (hereinafter referred to as resin composition α) containing at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less. Is formed. It includes at least one layer containing at least one type of polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one type of soft resin B having a tensile modulus of 200 MPa or less as a resin component, and the elongation in the MD direction And the film excellent in the moldability is obtained by being the stretched film whose elongation in the TD direction is 150 to 850%.
The elongation of the stretched film of the present invention in the longitudinal direction (hereinafter also referred to as “MD direction”) and the elongation in the width direction (hereinafter also referred to as “TD direction”) are 150 to 850%. The elongation in the MD direction and the elongation in the TD direction may be the same or different as long as both are within the above range. When the elongation is lower than 150%, sufficient followability and / or sticking property cannot be obtained. If the elongation is higher than 850%, it is impossible to suppress a decrease in formability due to drawdown during thermoforming because orientation is insufficient. The elongation in the MD direction and the elongation in the TD direction of the stretched film of the present invention are preferably 180% or more, more preferably 210% or more, and still more preferably, from the viewpoint of obtaining sufficient followability and stickability. Is 230% or more, and particularly preferably 260% or more. The elongation in the MD direction and the elongation in the TD direction of the stretched film of the present invention are preferably 830% or less, more preferably 820% or less, from the viewpoint of easily suppressing a decrease in formability due to drawdown. More preferably, it is 800% or less. In particular, when the stretched film of the present invention is a single layer film, the elongation in the MD direction and the elongation in the TD direction are preferably 750% or less, more preferably 700% or less, and still more preferably. It is 670% or less, particularly preferably 650% or less.

  In general, the elongation tends to decrease as the stretching ratio during stretching increases. Therefore, for example, in a film obtained by stretching the resin composition α at a higher magnification in the TD direction than in the MD direction, the elongation in the TD direction is lower than the elongation in the MD direction. In the film obtained by stretching at a higher magnification in the MD direction, the elongation in the MD direction is lower than the elongation in the TD direction.

  The elongation can be measured according to JIS K-7127 (1999). Specifically, for example, a test piece (for example, test piece type 2, width 15 mm, length 140 mm) is cut out from a stretched film, and a tensile tester (for example, Universal Tensile Tester Technograph TGI-1kN manufactured by Minebea Co., Ltd.) is used. The measurement is performed at 23 ° C., a distance between chucks of 60 mm, and a test speed of 120 mm / min. The elongation is the elongation at break.

  The ratio of the elongation in the TD direction to the elongation in the MD direction of the stretched film of the present invention (the elongation in the TD direction / the elongation in the MD direction) is preferably 0.3 to from the viewpoint of easily improving the moldability of the film. It is 3.0, More preferably, it is 0.7-1.5, More preferably, it is 0.8-1.3.

  Both the MD elongation and the TD heating elongation of the stretched film of the present invention measured at 120 ° C. by the TMA method are preferably −2% to 8%. In this embodiment, the heating elongation rate in the MD direction and the heating elongation rate in the TD direction may be the same as or different from each other as long as both are within the above range. From the viewpoint of obtaining an appropriate stretchability during thermoforming, the MD elongation and the TD heating elongation of the stretched film of the present invention are more preferably 0% or more, and even more preferably 1% or more. is there. In the stretched film of the present invention, the MD elongation and the TD heating elongation are more preferably 5% or less, and more preferably from the viewpoint of easily suppressing a decrease in formability due to drawdown during thermoforming. Is 4.5% or less.

The heating elongation measured at 120 ° C. by the TMA method can be measured using a measuring device based on JISK7197. Specifically, for example, using a thermomechanical analyzer (for example, “SS-6000” manufactured by Seiko Instruments Inc.), the temperature is increased at a set temperature increase rate of 10 ° C./min under a load of 0.015 kgf / mm ^2. The dimensional change of the film when heated can be measured, and the dimensional change rate of the film at a furnace temperature of 120 ° C. with respect to the film at a furnace temperature of 25 ° C. can be measured as the heating elongation.

  The tensile elastic modulus in the MD direction and the tensile elastic modulus in the TD direction of the stretched film of the present invention are both preferably 1.5 GPa or less, and less than 1.0 GPa, from the viewpoint of obtaining sufficient followability and pastability. More preferably, it is less than 0.9 GPa, and particularly preferably 0.88 GPa or less. The tensile modulus in the MD direction and the tensile modulus in the TD direction are both preferably 0.2 GPa or more, more preferably 0.3 GPa or more, from the viewpoint of easily suppressing a decrease in formability due to drawdown. preferable. In this embodiment, the tensile modulus in the MD direction and the tensile modulus in the TD direction may be the same or different from each other as long as both are within the above range.

  In general, the tensile elastic modulus tends to increase as the stretching ratio at the time of stretching increases. Therefore, for example, in a film obtained by stretching the resin composition α at a higher magnification in the TD direction than in the MD direction, the tensile elastic modulus in the TD direction is higher than the tensile elastic modulus in the MD direction. In a film obtained by stretching at a higher magnification in the MD direction than in the TD direction, the tensile elastic modulus in the MD direction is higher than the tensile elastic modulus in the TD direction.

  The stretched film of the present invention preferably has a thickness of 10 μm or more, more preferably 15 μm or more, from the viewpoint of preventing partial elongation and deformation of the film. The stretched film of the present invention preferably has a thickness of 200 μm or less, more preferably 150 μm or less, and still more preferably 130 μm or less, from the viewpoint of followability and / or stickability.

  The thickness of the film can be measured using a thickness measuring instrument (for example, “MEI-11” manufactured by Citizen Seimitsu Co., Ltd.) in accordance with JIS-C2330.

  The haze of the stretched film of the present invention may be arbitrarily adjusted according to the appearance required for the molded product. For example, when the stretched film of the present invention is used for molding a transparent container, or a decorative film or a surface protective film. In applications where transparency is particularly required, such as when used as the content of the molded body formed from the stretched film of the present invention, or from the viewpoint of increasing the visibility of the adherend, it is preferably 10 or less, more preferably Is 6 or less, more preferably 4 or less.

  The haze of the film can be measured using a haze meter (for example, “NDH-5000” manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K7136.

  The stretched film of the present invention having the above characteristics includes a resin composition containing at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less ( At least one layer formed from the resin composition α) is included.

Polypropylene resin A
The tensile elastic modulus of the polypropylene resin A is 1000 MPa or more, preferably 1050 MPa or more, more preferably 1100 MPa or more, and further preferably 1150 MPa or more, from the viewpoint of suppressing moldability reduction due to drawdown. The tensile elastic modulus of the polypropylene resin A is preferably 1700 MPa or less, more preferably 1600 MPa or less, and further preferably 1500 MPa or less, from the viewpoint of improving stretchability when producing a film.
The tensile elastic modulus of the polypropylene resin A can be measured using a press sheet formed from the polypropylene resin A as a measurement sample. The details of the conditions for forming the press sheet are as shown in the examples. The tensile modulus of the press sheet is determined using a tensile tester (for example, Universal Tensile Tester Technograph TGI-1kN manufactured by Minebea Co., Ltd.) in accordance with JIS K-7127 (1999) using the press sheet as a measurement sample. Then, measurement is performed under the conditions of 23 ° C., a distance between chucks of 60 mm, and a test speed of 120 mm / min.

  The polypropylene resin A is not particularly limited as long as it is a polypropylene resin having a tensile modulus of 1000 MPa or more. For example, a homopolymer of propylene, and propylene and ethylene or an α- of 4 to 20 carbon atoms. And copolymers with olefins (eg butene, pentene, hexene, etc.). When the polypropylene resin A is a copolymer of propylene and ethylene or α-olefin, any of a random copolymer and a block copolymer may be used, but from the viewpoint of easily obtaining heat resistance and the above-mentioned preferable range of tensile elastic modulus. The content of monomers other than propylene in the copolymer is preferably 12% or less, more preferably 8% or less, further preferably 6% or less, particularly preferably 4% or less, and most preferably 2% or less. From the viewpoint of easily obtaining heat resistance and the above-mentioned preferable range of tensile elastic modulus, homopolypropylene or a copolymer of propylene and ethylene is preferable.

  Such a polypropylene resin A is, for example, a method of polymerizing propylene in a hydrocarbon solvent using a Ziegler-Natta catalyst system made of titanium or an aluminum compound; a method of polymerizing in liquid propylene (bulk polymerization); It can manufacture by well-known methods, such as the method of superposing | polymerizing :. Moreover, you may use a commercial item as the polypropylene resin A. Examples of commercially available products include, for example, “Prime Polypro (registered trademark) F300SP” manufactured by Prime Polymer Co., Ltd., “PC412A” manufactured by Sun Allomer Co., Ltd., “Novatech (registered trademark) FB3HAT” manufactured by Nippon Polypro Co., Ltd., “Wintech” (Registered trademark) WFW5T ", Borealis Daploy series, Korea Oil Chemical Co., Ltd. 5014L series, Sumitomo Chemical Co., Ltd. Sumitomo Nobren (registered trademark) series, and the like.

By changing the roughness of the film surface, it is possible to improve the winding property and to adjust the appearance (feel, gloss, etc.) of the molded product for use as a decorative film. It is preferable to use a block copolymer of propylene and ethylene as the polypropylene resin A of the stretched film of the present invention because the roughness of the film surface can be changed to a desired roughness. The block copolymer of propylene and ethylene can be used singly or in combination of two or more, or mixed with polypropylene resin A other than the block copolymer of propylene and ethylene.
In addition, both the homopolymer (homopolymer) and the block copolymer of propylene can be used equally as the polypropylene resin A, and should be used in a preferable type and a preferable mixing ratio depending on the appearance and surface roughness of the film. Can do.

  Examples of typical commercially available block copolymers of propylene and ethylene include “NOVATEC (registered trademark) PP BC6DRF”, “NOVATEC (registered trademark) PP BC4FC” manufactured by Nippon Polypro Co., Ltd., “Prime Polypro ( Registered trademark) J715M "and the like.

  The melt flow rate (MFR) of the polypropylene resin A is preferably 0.5 to 10 g / 10 minutes, more preferably 1 to 8 g / 10 minutes, and still more preferably 2 from the viewpoint of melt extrusion moldability. ~ 6 g / 10 min. MFR can be measured at 230 ° C. and a load of 21.18 N using a melt flow indexer (for example, a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K-7210 (1999).

  The weight average molecular weight (Mw) of the polypropylene resin A is preferably 200 to 600,000, more preferably 300 to 500,000 from the viewpoint of stretchability during film production.

  The molecular weight distribution (Mw / Mn) calculated as the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polypropylene resin A is from the viewpoint of improving stretchability and thermoformability during film production. , Preferably 3-11, more preferably 4-10.

  The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polypropylene resin A can be measured by a gel permeation chromatography (GPC) method. The GPC apparatus used for the GPC method is not particularly limited, and is a commercially available high-temperature GPC measuring instrument capable of molecular weight analysis of polyolefins (for example, a high-temperature GPC measuring instrument with a built-in differential refractometer (RI) manufactured by Tosoh Corporation). , HLC-8121GPC-HT) or the like. In this case, for example, a column made by connecting three TSKgel GMHHR-H (20) HT manufactured by Tosoh Corporation, column temperature: 140 ° C., eluent: trichlorobenzene, flow rate: 1.0 ml / min. Can be measured. Usually, a calibration curve is prepared using standard polystyrene, and a weight average molecular weight (Mw) and a number average molecular weight (Mn) are obtained by polystyrene conversion.

  The mesopentad fraction (mmmm) of the polypropylene resin A is preferably 90 mol% or more, more preferably 91 to 99.5 mol%, still more preferably 92 to 99 mol%. By using such a polypropylene-based resin A, it becomes easy to obtain a film that has excellent heat resistance and is less prone to partial elongation and deformation of the film.

The mesopentad fraction ([mmmm]) is an index of stereoregularity that can be obtained by high-temperature Fourier transform nuclear magnetic resonance apparatus (high-temperature FT-NMR) measurement. Specifically, for example, a polypropylene resin is dissolved in a solvent, and using a high-temperature Fourier transform nuclear magnetic resonance apparatus (for example, “JNM-ECP500” manufactured by JEOL Ltd.), observation nucleus: ¹³ C (125 MHz), Measurement temperature: 135 ° C., solvent: ortho-dichlorobenzene [ODCB: mixed solvent of ODCB and deuterated ODCB (volume ratio = 4/1)], measurement mode: single pulse proton broadband decoupling, pulse width: 9.1 μsec (45 ° pulse), pulse interval: 5.5 sec, integration number: 4500 times, shift standard: CH ₃ (mmmm) = 21.7 ppm, for example, “Nippon Analytical Chemistry / Polymer” Analytical Research Roundtable, New Edition Polymer Analysis Handbook, Kinokuniya, 1995, page 610 " It can be carried out.

  The pentad fraction representing the degree of stereoregularity is a combination of pentads (mmmm and “meso (m)”) arranged in the same direction and “Rasemo (r)” arranged in the opposite direction. calculated as a percentage (%) based on the integrated value of the intensity of each signal derived from mrrm and the like. Each signal derived from mmmm, mrrm and the like can be assigned with reference to, for example, “T. Hayashi et al., Polymer, 29, 138 (1988)”.

  The content of the polypropylene resin A in the resin composition α is preferably 90% by mass or less based on the total amount of the resin composition α, from the viewpoint of easily obtaining sufficient followability and pastability, and 85% by mass. More preferably, it is more preferably 80% by mass or less. The content of the polypropylene resin A in the resin composition α is preferably 30% by mass or more based on the total amount of the resin composition α, from the viewpoint of easily suppressing a decrease in moldability due to drawdown, and 35% by mass. More preferably, it is more preferably 40% by mass or more. The layer formed from the resin composition α, that is, the layer containing the polypropylene resin A and the soft resin B as a resin component, is preferably 90% by mass or less based on the total amount of the resin component. More preferably, it is 85 mass% or less, More preferably, it contains 80 mass% or less. The layer containing the polypropylene resin A and the soft resin B as a resin component is preferably 30% by mass or more, more preferably 35% by mass or more, based on the total amount of the resin component of the polypropylene resin A. Preferably it contains 40 mass% or more.

Soft resin B
The tensile elastic modulus of the soft resin B is 200 MPa or less, preferably 180 MPa or less, more preferably 150 MPa or less, and still more preferably 100 MPa or less, from the viewpoint of obtaining sufficient followability and stickability. The tensile elastic modulus of the soft resin B is preferably 5 MPa or more, more preferably 7 MPa or more, and even more preferably 10 MPa or more, from the viewpoint of easily suppressing a decrease in moldability due to drawdown.
The tensile elastic modulus of the soft resin B can be measured using a press sheet formed from the soft resin B as a measurement sample. The details of the conditions for forming the press sheet are as shown in the examples, and the method of measuring the tensile modulus is as described above.

  The soft resin B is not particularly limited as long as it has a tensile modulus of 200 MPa or less. Examples thereof include polyethylene, polyolefin-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, polyester-based thermoplastic elastomer, and polyamide-based thermoplastic elastomer. It is done. Further, from the viewpoint of improving the miscibility with the polypropylene resin A and easily obtaining a smooth and highly transparent film, the soft resin B is preferably a polyethylene, a polyolefin thermoplastic elastomer, or a polystyrene elastomer. Examples of the polyolefin-based thermoplastic elastomer include an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, and an ethylene-propylene terpolymer. Examples of polystyrene-based thermoplastic elastomers include styrene-butadiene block copolymers.

  Such a soft resin B can be produced by a known polymerization method. A commercial product may be used as the soft resin B. Examples of commercially available products include, for example, “El Modu (registered trademark) S400, S600 and S901” manufactured by Idemitsu Kosan Co., Ltd., “Tuffmer (registered trademark) PN2060, PN3560” manufactured by Mitsui Chemicals, Inc., “Tough Selenium” manufactured by Sumitomo Chemical Co., Ltd. (Registered trademark) H3712D ”,“ Welnex (registered trademark) RFX4V ”manufactured by Nippon Polypro Co., Ltd.,“ Thermo Run (registered trademark) 3705N ”manufactured by Mitsubishi Chemical Corporation,“ Lavalon (registered trademark) SJ5400N ”manufactured by Mitsubishi Chemical Corporation, etc. Can be mentioned.

  The melt flow rate (MFR) of the soft resin B is preferably 1 to 400 g / 10 minutes, more preferably 1 to 100 g / 10 minutes (230 ° C., load 21.18 N, JIS K) from the viewpoint of extrusion moldability. -7210 (measured in 1999)). The method for measuring MFR is as described above.

  The content of the soft resin B in the resin composition α is preferably 70% by mass or less, based on the total amount of the resin composition α, and preferably 65% by mass or less from the viewpoint of easily suppressing a decrease in moldability due to drawdown. It is more preferable that it is 60 mass% or less. The content of the soft resin B in the resin composition α is preferably 10% by mass or more based on the total amount of the resin composition α, and is preferably 15% by mass or more, from the viewpoint of easily obtaining sufficient followability and pastability. More preferably, it is more preferably 20% by mass or more. The layer formed from the resin composition α, that is, the layer containing the polypropylene resin A and the soft resin B as the resin component, is preferably 70% by mass or less based on the total amount of the resin component. Preferably it is 65 mass% or less, More preferably, it contains 60 mass% or less. The layer containing the polypropylene resin A and the soft resin B as a resin component is preferably 10% by mass or more, more preferably 15% by mass or more, based on the total amount of the resin component. Preferably it contains 20 mass% or more.

  The polypropylene resin A and the soft resin B preferably have an ash content of 100 ppm or less. Ash content is caused by polymerization catalyst residue and the like, and causes fine foreign matters (fish eyes). Fisheye can be prevented as the ash content is 100 ppm or less, preferably 50 ppm or less. The ash content can be adjusted by a method for controlling the type and amount of catalyst used during polymerization.

In this specification, content of ash is measured as follows based on ISO3451-1.
Polypropylene resin A and / or soft resin B are put in a crucible, heated in a muffle furnace at 750 ° C. for 1 hour, and the mass of the residue in the crucible is measured. And the ratio of the mass of the residue in a crucible with respect to the mass of the polypropylene resin A and / or soft resin B which was thrown into the crucible is calculated, and this is made into content of ash.

In addition to the polypropylene resin A and the soft resin B, the resin composition α for forming the stretched film of the present invention is a resin other than the polypropylene resin A and the soft resin B, or a resin other than the polypropylene resin (hereinafter, “polypropylene resin”). Other resins ”may be mixed within a range that does not impair the effects of the present invention. Here, the “other resins” are not particularly limited, and conventionally known resins that are suitable for stretched film applications can be used as appropriate in the present invention.
Other resins include, for example, polyolefins other than polypropylene, such as polyethylene, poly (1-butene), polyisobutene, poly (1-pentene), poly (4-methyl-1-pentene), and ethylene-propylene copolymer. Copolymer, propylene-butene copolymer, ethylene-butene copolymer, etc., copolymer of α-olefins, vinyl monomer-diene monomer random copolymer, such as styrene-butadiene random copolymer, And vinyl monomer-diene monomer-vinyl monomer random copolymer such as styrene-butadiene-styrene block copolymer.
The blending amount of such other resins is preferably 10% by mass or less, preferably 5% by mass or less based on the total amount of the polypropylene resin A and the soft resin B contained in the resin composition α. More preferred.

In addition to the polypropylene resin A and the soft resin B, the resin composition α for forming the stretched film of the present invention may contain at least one additive as necessary. In general, the additive is not particularly limited as long as it is an additive used for a polypropylene resin. Examples of such additives include stabilizers such as antioxidants, chlorine absorbers, ultraviolet absorbers, lubricants, plasticizers, flame retardants, antistatic agents, colorants, antiblocking agents and the like. Such an additive may be added to the resin composition α within a range not impairing the effects of the present invention.
However, it is preferable that the resin composition α for forming the stretched film of the present invention does not contain a nucleating agent. When the resin composition α does not contain a nucleating agent, it is preferable because followability during thermoforming is improved and stretchability is improved. The stretched film of the present invention may be a single layer film or a multilayer film.

“Antioxidant” has a role as a primary agent for the purpose of suppressing deterioration due to heat and oxidation in an extruder during production of stretched films, and suppresses deterioration over time when used for a long time. At least as a secondary agent to be blended for the purpose of. Depending on these roles, different types of antioxidants may be used, or one type of antioxidant may have two roles.
When different types of antioxidants are used, for example, 2,6-di-tert-butyl-p-cresol (generic name: BHT) is used as the primary agent for the purpose of suppressing deterioration in the extruder. It is preferable to add about 1000 to 3000 ppm in the composition α. Most of the antioxidant compounded for this purpose is consumed in the molding process in the extruder, and hardly remains in the stretched polypropylene film. Therefore, generally, the remaining amount is less than 100 ppm, which is preferable in that the content of the molded body and the adherend are hardly contaminated by the antioxidant.
As the secondary agent, known antioxidants can be used, and examples thereof include phenol-based, hindered amine-based, phosphite-based, lactone-based, and tocopherol-based thermal stabilizers and antioxidants. Specifically, dibutylhydroxytoluene, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6-tris ( 3,5-di-t-butyl-4hydroxy) benzene, tris (2,4-di-t-butylphenyl) phosphite and the like. More specifically, examples include Irganox (registered trademark) 1010, Irganox (registered trademark) 1330, and Irgafos (registered trademark) 168, which are antioxidants manufactured by BASF Japan.
Among them, at least one selected from phenolic antioxidants or a combination thereof, a combination of phenolic and phosphite, a combination of phenolic and lactone, a phenolic, phosphite and lactone The combination is preferable because it can impart an effect of suppressing deterioration over time when the film is used for a long time.
Moreover, you may use phosphorus antioxidant as a secondary agent. Examples of phosphorus antioxidants include tris (2,4-di-t-butylphenyl) phosphite (trade name: Irgaphos 168), bis (2,4-di-t-butyl-6-methylphenyl) ethyl. And phosphite (trade name: Irgaphos 38).
The content of the antioxidant as the secondary agent is preferably 300 ppm or more and 2500 ppm or less, and more preferably 500 ppm or more and 1500 ppm or less, based on the total amount of the polypropylene resin A and the soft resin B contained in the resin composition α. By making it 300 ppm or more, it is easy to give the effect of suppressing deterioration over time when the film is used for a long period of time, and by making it 2500 ppm or less, it prevents contamination of the contents of the molded product and the adherend by an antioxidant. It's easy to do.

  The “chlorine absorbent” is not particularly limited as long as it is usually used for polypropylene. Examples of the chlorine absorbent include metal soaps such as calcium stearate.

  The “ultraviolet absorber” is not particularly limited as long as it is usually used for polypropylene. Examples of the ultraviolet absorber include benzotriazole (such as Tinuvin 328 manufactured by BASF Japan), benzophenone (such as Cysorb UV-531 manufactured by Cytec), and hydroxybenzoate (such as UV-CHEK-AM-340 manufactured by Ferro).

  The “lubricant” is not particularly limited as long as it is normally used for polypropylene. Examples of the lubricant include primary amides (such as stearic acid amides), secondary amides (such as N-stearyl stearic acid amides), ethylene bisamides (such as N, N′-ethylene bisstearic acid amides), and the like.

  The “plasticizer” is not particularly limited as long as it is a commonly used one for polypropylene. As a plasticizer, PP random copolymer etc. are mentioned, for example.

  The “flame retardant” is not particularly limited as long as it is usually used for polypropylene. Examples of the flame retardant include halogen compounds, aluminum hydroxide, magnesium hydroxide, phosphates, borates, and antimony oxides.

  The “antistatic agent” is not particularly limited as long as it is usually used for polypropylene. Examples of the antistatic agent include glycerin monoesters (glycerin monostearate and the like), ethoxylated secondary amines, and the like.

  The “colorant” is not particularly limited as long as it is usually used for polypropylene. Examples of the colorant include cadmium, chromium-containing inorganic compounds, azo, quinacridone organic pigments, and the like.

  The “anti-blocking agent” is usually used for polypropylene and is not particularly limited as long as the effect as a nucleating agent is not exhibited. Examples thereof include talc, zeolite, silica, fatty acid amide, fatty acid glycerin ester compound and the like.

  The stretched film of the present invention can be obtained by stretching the resin composition α according to a usual method. In the present invention, the above resin composition α is used for stretching as it is, or a “cast raw sheet before stretching” for producing a stretched film may be formed using a known method. . When using the cast raw sheet before stretching, for example, resin pellets of polypropylene resin A and soft resin B are mixed with resin pellets and / or powder mixed with polypropylene resin A and soft resin B, or in advance, Mixed resin pellets produced by melting and kneading polypropylene resin A and soft resin B are supplied to an extruder, heated and melted, passed through a filter, and then 170 ° C to 300 ° C, preferably 200 ° C to Heat-melt to 270 ° C., melt-extrude from T-die, and cool with at least one metal drum held at 20 ° C. to 100 ° C., preferably 25 ° C. to 90 ° C., more preferably 30 ° C. to 80 ° C. By solidifying, an unstretched cast original fabric sheet can be formed. It is preferable to adjust the thickness of the said cast raw fabric sheet according to the thickness after extending | stretching, and is about 0.5-5 mm normally.

The stretched film of the present invention can be produced by subjecting the resin composition α or the cast original fabric sheet before stretching to stretching. As a method of using the resin composition α for stretching as it is, there are inflation molding and tubular stretching. Inflation molding is performed by melting raw materials with an extruder, extruding molten resin from an annular die into a tube shape, filling gas inside the tube through a hole provided inside the annular die, and supplying it from a blower while blowing up. Air is blown from the air ring to the outer surface of the tube to cool and solidify to form bubbles and wind up. The blow ratio represented by the ratio of the bubble diameter to the die diameter at the time of blow-up can be used as an index of the draw ratio. Tubular stretching is a method in which bubbles are blown up in the same manner after inflation molding to form bubbles and wound up. The product of the blow ratio at the time of inflation molding and the blow ratio at the time of tubular stretching can be used as an index of the draw ratio.
Examples of the method for performing the stretching treatment on the original cast sheet before stretching include sequential biaxial stretching in the MD direction and TD direction, and simultaneous biaxial stretching. As a method of sequential biaxial stretching or simultaneous biaxial stretching, there are a tenter method, a method of stretching between rolls provided with a peripheral speed difference, etc., but the tensile modulus and elongation are controlled by precisely controlling the stretching ratio. From the viewpoint that it is easy to make a preferable range of the tenter method, the biaxial stretching method by the tenter method, the sequential biaxial stretching method by the tenter method, and the width direction by the tenter method after stretching in the flow direction between rolls provided with a peripheral speed difference A sequential biaxial stretching method is preferably used.
From the viewpoint of easily improving the isotropy of the film, stretching is preferably performed by sequential biaxial stretching, simultaneous biaxial stretching, inflation molding, and tubular stretching, and by simultaneous biaxial stretching, inflation molding, and tubular stretching. Is more preferable. In addition, since the inflation molding is a molding method in which the resin composition α is stretched by bubbles formed by enclosing gas inside the tube as described later, in this specification, the film obtained by inflation molding is also stretched. Included in the film.

  In the case of sequential biaxial stretching or simultaneous biaxial stretching, the stretching ratio in the MD direction in stretching is preferably 2 to 6 and more preferably 2.5 to 5 from the viewpoint of easily obtaining sufficient followability and stickability. It is 5.5, More preferably, it is 2.8-4.5. The draw ratio in the TD direction is preferably 2 to 6, more preferably 2.5 to 5.5, and even more preferably 2.8 to 4. from the viewpoint of easily obtaining sufficient followability and pastability. 5.

  As the sequential biaxial stretching method, for example, the cast raw sheet is first maintained at a temperature of 100 to 160 ° C. and passed between rolls provided with a speed difference, or led to a tenter and preferably 2 to 6 times in the flow direction. More preferably, the film is stretched to 2.5 to 5.5 times, more preferably 2.8 to 4.5 times, and then relaxed by about 0 to 10% as necessary. Subsequently, the uniaxially stretched film is guided to a tenter and preferably at a temperature of 120 to 170 ° C., preferably 2 to 6 times, more preferably 2.5 to 5.5 times, and further preferably 2.8 to 4 in the width direction. After stretching by 5 times, it is relaxed by about 0 to 10% as necessary, heat-set, and wound up. By setting the draw ratio within the above range, the tensile modulus and elongation can be easily set within the above-described preferred ranges.

  In the simultaneous biaxial stretching method, the cast original fabric sheet is guided to a tenter and stretched at the temperature of 120 to 170 ° C. in the flow direction and the width direction to the above stretching ratio, and then relaxed by about 0 to 10% as necessary. Then, heat set and wind up.

  In the case of inflation molding or tubular stretching, the stretching ratio is preferably 1.2 to 3, more preferably from the viewpoint of maintaining sufficient followability and stickability and easily suppressing moldability degradation due to drawdown. It is 1.3-2.5, More preferably, it is 1.5-2.3.

  In inflation molding, the resin is heated and melted at 200 ° C. to 270 ° C., the molten resin is extruded from the annular die into a tube shape, gas is sealed inside the tube through a hole provided inside the annular die, and the blow ratio is 1.2 to 3, preferably after forming and stretching bubbles to be 1.3 to 2.5, if necessary, relaxing about 0 to 10%, cooling and solidifying, and winding. Here, the blow ratio is the ratio between the bubble diameter and the die diameter, and is an index of the draw ratio of the resin composition α.

  In tubular stretching, gas is sealed inside a tubular sheet obtained by inflation molding, bubbles are formed and stretched so that the blow ratio is 1.2 to 2.0, and then 0 to 10 as necessary. % Relaxed, heat-set and wound.

  The wound film can be cut to a desired product width after being subjected to an aging treatment in an atmosphere of about 20 to 45 ° C. as necessary. The stretched film of the present invention can be subjected to surface treatment such as corona discharge treatment or plasma discharge treatment as necessary. By surface treatment, it is possible to adjust wettability and adhesiveness when a coating layer or an adhesive layer is provided or when it is attached to an object to be protected. A known method can be adopted for the surface treatment.

  The surface of the stretched film of the present invention is provided with a fine surface roughness that improves winding ability, for example, in the range where there is no hindrance to pasting and the like when used as a film for surface protection or surface protection during thermoforming. Is preferred.

  The stretched film preferably has a surface roughness of 0.03 μm or more and 1.5 μm or less, more preferably 0.05 μm or more and 0.5 μm or less, on the center line average roughness (Ra) on at least one surface. 0.05 μm or more and 0.25 μm or less is more preferable. Further, it is preferable that the surface is finely roughened to have a maximum height (Rz, Rmax in the old JIS definition) of 0.2 μm to 15 μm. When Ra and Rz are in the above-mentioned preferable ranges, the surface can be a finely roughened surface, so that good pastability is obtained and the appearance of the molded product when used as a decorative film ( It is also possible to adjust the feeling of touch and gloss.

  Here, “Ra” and “Rz” (Rmax defined in the former JIS definition) are, for example, a stylus type surface roughness meter that is generally widely used by a method defined in JIS-B0601: 2001 or the like. The value measured using a stylus type surface roughness meter (for example, a diamond needle). More specifically, “Ra” and “Rz” are defined in JIS-B0601: 2001 using, for example, a three-dimensional surface roughness meter (for example, “Surfcom 1400D-3DF-12 type” manufactured by Tokyo Seimitsu Co., Ltd.). Can be determined according to the method.

  Moreover, as above-mentioned, in order to obtain the external appearance and surface roughness of a desired film, the kind and mixing ratio of polypropylene resin A can be selected suitably.

  As a method for giving fine irregularities on the film surface, various known roughening methods such as an embossing method, an etching method, a blending method, and a method using a β crystal can be employed.

  The impact strength of the stretched film of the present invention is not limited, but is preferably 0.04J or more and 1.2J or less, more preferably 0.05J or more and 1.1J or less, and 0.05J or more and 1J or less. Is more preferable. When it is in the above range, better toughness can be obtained as a film while maintaining good moldability, and it is not broken when used for packaging containers such as daily necessities (when handling).

  Here, the impact strength is measured using a generally used film impact tester (for example, “Film Impact Tester No. 181” manufactured by Yasuda Seiki Seisakusho Co., Ltd.) by a method defined in JIS K7124, for example. Value.

  The stretched film of the present invention may be a single-layer film containing polypropylene resin A and soft resin B as resin components, or at least one layer containing polypropylene resin A and soft resin B as resin components. A multilayer film may be included. That is, the stretched film of the present invention may be a single-layer film composed only of layers formed from the resin composition α, or may be a multilayer film including at least one layer composed of the resin composition α. . When the stretched film of the present invention is a multilayer film, a plurality of multilayer films obtained by laminating a single layer of the stretched film of the present invention, that is, a plurality of stretched films of the present invention composed of a single layer are prepared, and then the plurality A multilayer film obtained by laminating stretched films of each other (the types of stretched films may be different or the same), resin composition α and “resin R” or “resin R” (Hereinafter referred to as resin composition β. Here, the resin composition β does not contain a polypropylene resin A and a soft resin B in combination, as will be described later) and is laminated by coextrusion. It may be a multilayer film obtained by stretching, a laminate of the stretched film of the present invention and another film, or a multilayer unstretched film, each layer of the unstretched film. An unstretched film which is a layer containing the polypropylene resin A and the soft resin B [(1) Prepare a plurality of unstretched films of the stretched film of the present invention composed of a single layer, and then unstretch them. A multilayer unstretched film obtained by laminating films to each other (the type of stretched film may be different or the same), (2) a film before stretching of the stretched film of the present invention composed of a single layer A multilayer unstretched film obtained by co-extrusion of the resin composition α so as to form a plurality of layers (multilayer) (the type of the resin composition α may be different or the same), etc.), and then A multilayer film obtained by stretching the unstretched film may be used. Here, from the viewpoint of not impairing the effects of the present invention, the resin R is preferably a resin having a tensile modulus of 350 MPa or less, and more preferably a soft resin B. Examples of the resin R include polyethylene, polyolefin-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, and the like. These resin components can be used alone or in combination of two or more. Moreover, the stretched film of this invention may have an adhesive layer on the film surface as needed.

  When the stretched film of the present invention is a multilayer film, preferred multilayer films include a multilayer film including two layers composed of the resin composition α, a layer composed of the resin composition α, and a layer composed of the resin R or the resin composition β. And a multilayer film comprising a layer composed of the resin composition α, a layer composed of the resin R or the resin composition β, and a layer composed of the resin composition α in this order. In the stretched film of the present invention, the layer structure can be changed depending on the application. When the stretched film of the present invention is a multilayer film, the thickness of each layer is not particularly limited, and can be appropriately set according to the thickness of the entire multilayer stretched film of the present invention.

Here, the layer made of the resin R or the resin composition β will be described. The “resin R” means a resin (or resin component) that does not use both the polypropylene resin A and the soft resin B, and the layer made of the resin R or the resin composition β It means a layer that is not a layer that uses both the polypropylene resin A and the soft resin B together. In other words, the layer made of the resin R or the resin composition β includes (i) a layer that includes the polypropylene resin A and does not include the soft resin B, and (ii) includes the soft resin B and includes the polypropylene resin. A layer that does not contain A, and (iii) a layer that does not contain any of the polypropylene resin A and the soft resin B and contains a resin R that does not fall under either the polypropylene resin A or the soft resin B. While including the embodiment, (iv) the embodiment of the layer containing both the polypropylene resin A and the soft resin B is not included. As the resin component in the above aspects (i) to (iii), it is preferable that the entire resin component has a tensile modulus of 350 MPa or less.
Specific examples of the “resin R” are as described above.
The layer made of the resin composition β may contain at least one or more additives as necessary in addition to the above-described resin R. Examples of such additives include stabilizers such as antioxidants, chlorine absorbers and ultraviolet absorbers, lubricants, plasticizers, flame retardants, antistatic agents, colorants, antiblocking agents and the like. Specific examples of these additives are the same as the specific examples of the additives in the resin composition α described above. The content of each of these additives is a resin R instead of “polypropylene resin A and soft resin B” described in the description of each additive in the layer containing the polypropylene resin A and the soft resin B. The same amount is preferable except that.
About the manufacturing method of the multilayer stretched film of this invention containing the layer which contains the said polypropylene resin A and the soft resin B as a resin component, and the layer which consists of resin R or resin composition (beta), it is as above-mentioned.
The thickness of the layer made of the resin R or the resin composition β is not limited, but from the thickness (T _a ) of the layer containing the polypropylene resin A and the soft resin B as resin components and the resin R or the resin composition β. The relationship with the layer thickness (T _b ) is preferably 0.25 ≦ (T _b / T _a ) ≦ 4, and preferably 0.33 ≦ (T _b / T _a ) ≦ 3. More preferably, it is more preferable that 0.5 ≦ (T _b / T _a ) ≦ 2.

In the embodiment in which the stretched film of the present invention has a pressure-sensitive adhesive layer, the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer is not limited at all. For example, acrylic resin, styrene-isobutylene-styrene copolymer, styrene-butylene-styrene copolymer Polymers, styrene-ethylene-butylene-styrene copolymers, polyisobutylene resins, natural rubber resins, styrene-butadiene copolymers, styrene-isoprene copolymers, olefin elastomers, and the like can be used. The method for forming the pressure-sensitive adhesive layer is not limited in any way, and may be appropriately selected according to the type of pressure-sensitive adhesive to be used. Examples of the method for forming the pressure-sensitive adhesive layer include a method in which an organic solvent in which the pressure-sensitive adhesive is dissolved or water in which the pressure-sensitive adhesive is dispersed is applied to the film and dried, a method in which the pressure-sensitive adhesive is melt-coated on the film, or And a method of coextruding the resin composition α and the pressure-sensitive adhesive at the time of film production. Although the quantity of an adhesive layer is not specifically limited, Usually, it is 5-40 g / m < ² >.

  The stretched film of the present invention has good followability and / or stickability and isotropic property, and is a raw material for various packaging materials used in food packaging, packaging of various parts, packaging of medical devices, etc. It is suitably used as a sheet, a decorative film, a protective film during molding, and the like. The stretched film of the present invention is used alone, or the stretched film of the present invention is used as a decorative film, a protective film at the time of molding, the stretched film of the present invention and other films and sheets, metals such as aluminum foil, etc. In a state where these are bonded together, a molded body formed into an arbitrary shape can be obtained by thermoforming such as vacuum forming and pressure forming. Examples of such a molded body include a communication device member such as a mobile phone, an information device member inside an automobile, a member of household appliances, a packaging container for daily necessities, and the like. The stretched film of the present invention having the above characteristics has sufficient followability that is suitable for thermoforming, particularly where the film is greatly stretched, such as deep drawing. Moreover, the stretched film of the present invention having the above characteristics is less likely to sag due to softening of a film called drawdown.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples, but these examples are for explaining the present invention and do not limit the present invention in any way. Unless otherwise specified, the terms “parts” and “%” indicate “parts by mass” and “% by mass”, respectively.

[Measurement of each characteristic value of resin]

(1) Tensile modulus A press sheet was prepared by the following procedure using a mini test press manufactured by Toyo Seiki Seisakusho. 5 g of resin pellets and a 200 μm thick spacer were sandwiched between metal foils and preheated at 200 ° C. for 2 minutes to melt the resin pellets. Next, after pressing for 2 minutes at a pressing pressure of 2 MPa, the molten resin sheet and the spacer were sandwiched between the metal foil and another mini-test press set at 20 ° C. and pressed for 1 minute at a pressing pressure of 2 MPa. The obtained sheet | seat was removed from metal foil and the spacer, and it used for the tensile elasticity modulus measurement.
Using the created press sheet as a sample, a sample conforming to JIS K-7127 (1999) and a sample shape conforming to test piece type 2 (sample width 15 mm, sample length 140 mm) was used, and a tensile tester (Minevea Corporation) Tensile modulus was measured using a universal tensile tester Technograph TGI-1kN) under the conditions of 23 ° C., test speed 120 mm / min, and distance between chucks 60 mm.

(2) Melt flow rate (MFR)
According to JIS K-7210 (1999), it measured using the melt indexer by Toyo Seiki Seisakusho. The measurement conditions were a measurement temperature of 230 ° C. and a load of 21.18N.

[Measurement of each characteristic value of film]
(3) Tensile modulus and elongation In accordance with JIS K-7127 (1999), the sample shape conforms to specimen type 2 (sample width 15 mm, sample length 140 mm), and a tensile tester (Minebea Corporation) Tensile elasticity tester and elongation at break in MD and TD directions under the conditions of 23 ° C., test speed 120 mm / min, and distance between chucks 60 mm using a company-made universal tensile tester Technograph TGI-1kN) Was measured.

(4) Heat elongation measured at 120 ° C. by the TMA method The heat elongation was performed by the TMA method according to JIS K7197. The measurement was performed using a thermomechanical analyzer (“SS-6000” manufactured by Seiko Instruments Inc.). A strip was cut out from the film so as to have a width of 30 mm in the measurement direction and a width of 4 mm in the direction perpendicular to the measurement direction. The distance between chucks is 15 mm, the dimensional change is measured from room temperature at a set temperature increase rate of 10 ° C / min and a constant load of 0.015 kgf / mm ² , and the dimensional change rate when the furnace temperature reaches 120 ° C is heated. It was set as the value of elongation.

(5) Thickness Based on JIS-C2330, the thickness was measured using a thickness measuring instrument (“MEI-11” manufactured by Citizen Seimitsu Co., Ltd.).

(6) Surface roughness The surface roughness was measured using a three-dimensional surface roughness meter (for example, “Surfcom 1400D-3DF-12 type” manufactured by Tokyo Seimitsu Co., Ltd.) with respect to the centerline average roughness (Ra), and JIS-B0601: The measurement was performed in accordance with the method defined in 2001.

(7) Impact strength The impact strength was measured using a film impact tester (“Film Impact Tester No. 181” manufactured by Yasuda Seiki Seisakusho Co., Ltd.) in accordance with the method defined in JIS K7124.

(8) Evaluation of drawdown The film obtained in each of the examples and comparative examples was cut into a size of 210 × 297 mm, and the opening was horizontally fixed to a frame having a size of 160 mm × 250 mm. The film is heated from above with a near infrared heater until the film temperature reaches 130 ° C. The degree of film sagging at that time was evaluated according to the following criteria.
A: The film drips in the initial stage of heating, but the amount of sag is small and the original shape is maintained immediately.
○: The film sag in the initial stage of heating, and the amount of sag is large, but the original shape is maintained, and there is no practical problem.
X: The film drips in the initial stage of heating, and then breaks without returning to the original shape.

(9) Evaluation of moldability An NGF molding machine (manufactured by Fuse Vacuum Co., Ltd.) was used for the evaluation of moldability.
The film obtained in each example and each comparative example was cut to a size of 210 × 297 mm, and the opening in the NGF molding machine was fixed horizontally to a frame having a size of 160 mm × 250 mm. A container having a length of 90 mm, a width of 60 mm, and a depth of 30.5 mm was set below the film in the NGF molding machine. After heating until the temperature of the film reached 110 ° C., a molded body was obtained by laminating the film on the container. The appearance of the molded body was judged according to the following criteria.
A: The film follows the container, and there is almost no uneven thickness, and the appearance is good.
○: The film follows the container and some thin portions are seen, but the appearance is generally good.
X: There are many portions where the film does not follow the container, the film is broken, and the appearance is poor.
XX: The film is drawn down during heating, and a molded product cannot be obtained.

Example 1
As the polypropylene resin A1, a crystalline polypropylene homopolymer (“Prime Polypro (registered trademark) F-300SP” manufactured by Prime Polymer Co., Ltd., MFR = 3 g / 10 min, melting point 161 ° C., tensile elastic modulus 1200 MPa) is used. As B1, a polyolefin-based thermoplastic elastomer (“Tafmer (registered trademark) PN2060” manufactured by Mitsui Chemicals, MFR = 6 g / 10 min, tensile modulus of elasticity 22 MPa) was used.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets were put into a single screw extruder A from a hopper and melted, and extruded from a single layer die as a single layer resin layer.
The extruded resin layer was cooled and solidified while being pressed with air pressure using an air knife on a cooling drum controlled at 35 ° C. to obtain a 900 μm-thick unstretched film.
The obtained unstretched film was simultaneously biaxially stretched using a batch type biaxial stretching machine “KARO IV” manufactured by Bruckner. Using the following apparatus settings and the stretch ratio of the unstretched film as the stretching conditions, a stretched film having a total thickness of about 100 μm was obtained.
Apparatus setting: Preheating temperature 165 ° C., preheating time 2 minutes, stretching temperature (longitudinal stretching temperature and transverse stretching temperature) 165 ° C., stretching rate 100% / second, stretching ratio of unstretched film: 3.3 times in the longitudinal direction After simultaneous biaxial stretching in the transverse direction 3.3 times, in the oven at a set temperature of 170 ° C., the longitudinal direction was relaxed to 3 times and the transverse direction was tripled, and then heat setting was performed for 20 seconds.

Example 2
A stretched film having a total thickness of 36 μm was obtained in the same manner as in Example 1 except that the stretch ratio of the unstretched film was changed as follows.
Stretch ratio of unstretched film: 5.5 times in the machine direction and 5.5 times in the transverse direction. After biaxial stretching, in the oven at a set temperature of 170 ° C, the machine direction is 5 times and the transverse direction is up to 5 times. After relaxation, heat setting was performed for 20 seconds.

Example 3
A stretched film having a total thickness of about 100 μm was obtained in the same manner as in Example 1 except that the amounts of the polypropylene resin A1 and the soft resin B1 were changed to the number of parts shown in Table 1.

Example 4
A stretched film having a total thickness of about 100 μm was obtained in the same manner as in Example 1 except that the amounts of the polypropylene resin A1 and the soft resin B1 were changed to the number of parts shown in Table 1.

Example 5
Instead of the soft resin B1, a polyolefin-based thermoplastic elastomer (“L-modu (registered trademark) S901” manufactured by Idemitsu Kosan Co., Ltd., MFR = 50 g / 10 min, tensile elastic modulus 75 MPa) as the soft resin B2 was used. Except for the above, a stretched film having a total thickness of about 100 μm was obtained in the same manner as in Example 1.

Example 6
Instead of the soft resin B1, except that a polyolefin-based thermoplastic elastomer (“Welnex (registered trademark) RFX4V” manufactured by Nippon Polypro Co., Ltd., MFR = 6 g / 10 min, tensile elastic modulus 182 MPa) was used as the soft resin B3. In the same manner as in Example 1, a stretched film having a total thickness of about 100 μm was obtained.

Example 7
Other than using polypropylene homopolymer ("Novatech (registered trademark) FB3HAT" manufactured by Nippon Polypro Co., Ltd., MFR = 7.5 g / 10 min, tensile elastic modulus 1700 MPa) as polypropylene resin A2 instead of polypropylene resin A1 Obtained a stretched film having a total thickness of about 100 μm in the same manner as in Example 1.

Example 8
As the polypropylene resin A3, a copolymer of propylene and ethylene (“Wintech (registered trademark) WFW5T” manufactured by Nippon Polypro Co., Ltd., MFR = 3.5 g / 10 min, melting point 142 ° C., tensile elastic modulus 1350 MPa) is used and is soft. As the resin B1, a polyolefin-based thermoplastic elastomer (“Tuffmer (registered trademark) PN2060” manufactured by Mitsui Chemicals, MFR = 6 g / 10 min, tensile elastic modulus 22 MPa) was used.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets were put into a single screw extruder A from a hopper and melted, and this was extruded as a single layer resin layer from an annular single layer die.
The extruded resin layer was cooled and solidified at a take-up speed of 18 m / min and a blow ratio of 1.8 to obtain a stretched film having a thickness of 60 μm. The take-up speed and blow ratio are conditions in inflation molding.

Example 9
As the polypropylene resin A3, a copolymer of propylene and ethylene (“Wintech (registered trademark) WFW5T” manufactured by Nippon Polypro Co., Ltd., MFR = 3.5 g / 10 min, melting point 142 ° C., tensile elastic modulus 1350 MPa) is used and is soft. As the resin B1, a polyolefin-based thermoplastic elastomer (“Tuffmer (registered trademark) PN2060” manufactured by Mitsui Chemicals, MFR = 6 g / 10 min, tensile elastic modulus 22 MPa) was used.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets were put into a single-screw extruder A and a single-screw extruder B from a hopper and melted, and these were laminated in a two-layer configuration of AB and extruded from a circular multilayer die as a two-layer laminate. . The ratio of the amount of extruded resin between the single screw extruder A and the single screw extruder B was 50:50.
The extruded resin layer was cooled and solidified at a take-up speed of 18 m / min and a blow ratio of 1.8 to obtain a stretched film having a thickness of 60 μm. The take-up speed and blow ratio are conditions in inflation molding. The stretched film of Example 9 is composed of two layers of layer A and layer B in order from the back surface, and the thickness of each of layer A and layer B is 30 μm.

Example 10
As the polypropylene resin A3, a copolymer of propylene and ethylene (“Wintech (registered trademark) WFW5T” manufactured by Nippon Polypro Co., Ltd., MFR = 3.5 g / 10 min, melting point 142 ° C., tensile elastic modulus 1350 MPa) is used and is soft. As the resin B1, a polyolefin-based thermoplastic elastomer (“Tuffmer (registered trademark) PN2060” manufactured by Mitsui Chemicals, MFR = 6 g / 10 min, tensile elastic modulus 22 MPa) was used.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets are put into a single-screw extruder A and a single-screw extruder B from a hopper and melted, and these are laminated in a three-layer configuration of A-B-A. Extruded. The ratio of the amount of extruded resin between the single screw extruder A and the single screw extruder B was 50:50.
The extruded resin layer was cooled and solidified at a take-up speed of 18 m / min and a blow ratio of 1.8 to obtain a stretched film having a thickness of 60 μm. The take-up speed and blow ratio are conditions in inflation molding. In addition, the stretched film of Example 10 is composed of three layers of layer A, layer B, and layer A ′ in order from the back surface, the thickness of layer A and layer A ′ is 15 μm, and the thickness of layer B is 30 μm. The description of Extruder A: Extruder B = 50: 50 in the resin amount ratio in Table 1 is actually Extruder A: Extruder B: Extruder A ′ = 25: 50: 25. The above description is the sum of the resin amount ratios of Extruder A and Extruder A ′.

Example 11
As the polypropylene resin A3, a copolymer of propylene and ethylene (“Wintech (registered trademark) WFW5T” manufactured by Nippon Polypro Co., Ltd., MFR = 3.5 g / 10 min, melting point 142 ° C., tensile elastic modulus 1350 MPa) is used and is soft. As the resin B1, a polyolefin-based thermoplastic elastomer (“Tuffmer (registered trademark) PN2060” manufactured by Mitsui Chemicals, MFR = 6 g / 10 min, tensile elastic modulus 22 MPa) was used.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets are put into a single screw extruder A and the soft resin B1 is put into a single screw extruder B from a hopper and melted, and these are laminated in a three-layer structure of A-B-A to form a three-layer laminate. Extruded from an annular multilayer die. The ratio of the amount of extruded resin between the single screw extruder A and the single screw extruder B was 50:50.
The extruded resin layer was cooled and solidified at a take-up speed of 18 m / min and a blow ratio of 1.8 to obtain a stretched film having a thickness of 60 μm. The take-up speed and blow ratio are conditions in inflation molding. In addition, the stretched film of Example 11 is composed of three layers of layer A, layer B, and layer A ′ in order from the back surface, the thickness of layer A and layer A ′ is 15 μm, and the thickness of layer B is 30 μm. The description of Extruder A: Extruder B = 50: 50 in the resin amount ratio in Table 1 is actually Extruder A: Extruder B: Extruder A ′ = 25: 50: 25. The above description is the sum of the resin amount ratios of Extruder A and Extruder A ′.

Example 12
As the polypropylene resin A3, a copolymer of propylene and ethylene (“Wintech (registered trademark) WFW5T” manufactured by Nippon Polypro Co., Ltd., MFR = 3.5 g / 10 min, melting point 142 ° C., tensile elastic modulus 1350 MPa) is used and is soft. as the resin B1, a polyolefin-based thermoplastic elastomer (manufactured by Mitsui Chemicals, Inc. "TAFMER (registered trademark) PN2060", MFR = 6 g / 10 min, tensile modulus 22 MPa) using as tree butter B4, polyethylene (Prime polymer Co., Ltd. “Evolue (registered trademark) SP2510”, MFR = 31 g / 10 minutes, tensile elastic modulus 260 MPa) was prepared.
These pellets were dry blended in the number of parts shown in Table 1 to prepare mixed raw material pellets. The mixed raw material pellets to a single screw extruder A, a tree fat B4 melted and poured from the hopper into a single screw extruder B, it was stacked in three layers of A-B-A, as a laminate of three layers Extruded from an annular multilayer die. The ratio of the amount of extruded resin between the single screw extruder A and the single screw extruder B was 50:50.
The extruded resin layer was cooled and solidified at a take-up speed of 18 m / min and a blow ratio of 1.8 to obtain a stretched film having a thickness of 60 μm. The take-up speed and blow ratio are conditions in inflation molding. In addition, the stretched film of Example 10 is composed of three layers of layer A, layer B, and layer A ′ in order from the back surface, the thickness of layer A and layer A ′ is 15 μm, and the thickness of layer B is 30 μm. The description of Extruder A: Extruder B = 50: 50 in the resin amount ratio in Table 1 is actually Extruder A: Extruder B: Extruder A ′ = 25: 50: 25. The above description is the sum of the resin amount ratios of Extruder A and Extruder A ′.

Comparative Example 1
A stretched film having a total thickness of about 100 μm was obtained in the same manner as in Example 1 except that only the polypropylene resin A1 was used without using the soft resin B1.

Comparative Example 2
A stretched film having a total thickness of 18 μm was obtained in the same manner as in Example 1 except that the stretch ratio of the unstretched film was changed as follows.
Stretch ratio of non-stretched film: 7.7 times in the vertical direction and 7.7 times in the horizontal direction, and then biaxially stretched in an oven at a set temperature of 170 ° C. After relaxation, heat setting was performed for 20 seconds.

Comparative Example 3
Instead of the soft resin B1, a polyolefin-based thermoplastic elastomer (“Tafmer (registered trademark) BL3450M” manufactured by Mitsui Chemicals, MFR = 9.0 g / 10 min, tensile elastic modulus 250 MPa) was used as the soft resin B5. Except for the above, a stretched film having a total thickness of about 100 μm was obtained in the same manner as in Example 1.

Comparative Example 4
Other than using polypropylene random copolymer ("Novatech (registered trademark) FW4BT", MFR = 6.5 g / 10 min, tensile elastic modulus 850 MPa, manufactured by Nippon Polypro Co., Ltd.) as polypropylene resin A4 instead of polypropylene resin A1 Obtained a stretched film having a total thickness of about 100 μm in the same manner as in Example 1.

Comparative Example 5
In the same manner as in Example 1, an unstretched film was obtained. The resulting unstretched film was sequentially biaxially stretched using a batch type biaxial stretching machine “KARO IV” manufactured by Bruckner. Using the following apparatus settings and the stretch ratio of the unstretched film as the stretching conditions, a stretched film having a total thickness of about 22 μm was obtained.
Apparatus setting: Preheating temperature 165 ° C., preheating time 2 minutes, stretching temperature (longitudinal stretching temperature and transverse stretching temperature) 165 ° C., stretching rate 100% / second Stretch ratio of unstretched film: 4.5 times in the longitudinal direction The film was stretched 10 times in the transverse direction, then relaxed to 9 times in the transverse direction in an oven at a set temperature of 170 ° C., and then heat fixed for 20 seconds.

Comparative Example 6
In the same manner as in Example 1, an unstretched film was obtained.

  As shown in Table 1, the stretched film of the present invention has good followability and excellent moldability. Moreover, it turns out that it is hard to draw down and has favorable thermoformability. On the other hand, the films of Comparative Examples 1 to 3, 5, and 6 that do not show the elongation in a predetermined range have poor followability and insufficient moldability. Moreover, the film of Comparative Examples 4 and 6 was easy to draw down, and a molded body was not obtained. Therefore, it includes at least one layer containing at least one polypropylene resin having a tensile modulus of 1000 MPa or more and at least one soft resin having a tensile modulus of 200 MPa or less as a resin component, and the elongation in the MD direction. It is understood that if the stretched film has an elongation in the TD direction of 150 to 850%, the moldability is excellent.

Claims (9)

A stretched film comprising at least one layer containing, as a resin component, at least one polypropylene resin A having a tensile modulus of 1000 MPa or more and at least one soft resin B having a tensile modulus of 200 MPa or less,
The elongation in the MD direction of elongation and TD direction of the stretched film are both Ri 150-850 percent der, the soft resin B is a polyolefin-based thermoplastic elastomer, a stretched film.   The stretched film according to claim 1, which is a multilayer film including at least one layer containing the polypropylene resin A and the soft resin B as resin components.   The stretched film of Claim 1 or 2 containing 90-30 mass% polypropylene resin A and 10-70 mass% soft resin B based on the total amount of a resin component.   The stretched film according to any one of claims 1 to 3, wherein a heating elongation in the MD direction and a heating elongation in the TD direction measured at 120 ° C by the TMA method are both -2 to 8%.   The stretched film according to any one of claims 1 to 4, wherein the ratio of the elongation in the TD direction to the elongation in the MD direction is 0.3 to 3.0.   The stretched film according to any one of claims 1 to 5, wherein the tensile modulus in the MD direction and the tensile modulus in the TD direction are both 1.5 GPa or less.   The stretched film according to claim 1, wherein the polypropylene resin A includes homopolypropylene or a copolymer of propylene and ethylene.   The stretched film according to any one of claims 1 to 7, wherein the MFR of the polypropylene resin A is 1 to 8 g / 10 min.   The stretched film according to claim 1, wherein the soft resin B has an MFR of 1 to 400 g / 10 minutes.