KR20210148096A - polypropylene film - Google Patents

Abstract

A polypropylene film having both a thermal contraction force of 400 mN or less in the main orientation axis direction and a direction perpendicular thereto at 140°C, and a Young's modulus in both the main orientation axis direction and a direction orthogonal thereto of 1.8 GPa or more. To provide a polypropylene film with excellent heat resistance and quality.

Description

polypropylene film

The present invention relates to a polypropylene film excellent in shrinkage properties at high temperatures and mechanical strength at high temperatures, and excellent in heat resistance, productivity, and quality.

Since the polypropylene film is excellent in transparency, mechanical properties, electrical properties, etc., it is used for various uses, such as a packaging use, a mold release use, a tape use, cable wrapping, and electrical uses including a capacitor|condenser. In particular, since it is excellent in surface releasability and mechanical properties, it is used suitably as a release film of various members, such as a plastics product, a building material, and an optical member, and a process film.

The properties required for the release film are appropriately set depending on the intended use thereof. As one of the methods used, after bonding to an adherend, a high-temperature process such as a heating roll or oven at 140 to 150° C. may be passed in some cases. In this case, PET film with excellent heat resistance has been used in many cases so far, but PET film lacks releasability and may not satisfy the required characteristics. have.

When the shrinkage force at high temperature is large, when bonding to the adherend and passing through the heating step, the shrinkage may cause peeling from the adherend or curling in some cases. In particular, polypropylene has a low melting point of about 160°C, and it is very difficult to suppress the shrinkage force of about 140 to 150°C.

As a means of heat-resistance, the example in which the shrinkage force in 120 degreeC was made low by making the heat processing temperature very high, and relaxing an orientation is described in patent document 1, for example. Further, Patent Documents 3 and 4 describe examples of lowering the thermal shrinkage rate by increasing the heat treatment temperature in the relaxation treatment and relaxing the orientation. Moreover, in patent document 2, the example of making low the thermal contraction rate by making the molecular weight of a polypropylene raw material low is described. Moreover, the example in which the shrinkage force in 140 degreeC was made low by making the relaxation rate after transverse stretching very large in patent document 5 is described.

In general, in order to lower the shrinkage force, a method of lowering the orientation of the polypropylene film is used, but when the polypropylene film has low mechanical strength at high temperature, a problem may occur. For example, when adhesive coating is applied to a polypropylene film and an adhesive layer is dried in a high-temperature oven, a problem in quality, such as wrinkles, may arise. Moreover, the example in which the shrinkage force in 140 degreeC was made low by making the relaxation rate after transverse stretching very large in patent document 5 is described.

From the above, it is required to lower the shrinkage force at high temperature and maintain the mechanical strength at high temperature. When it is relieved, a contractile force may be generated and the contractile force may become large. That is, shrinkage force and mechanical strength are a trade-off relationship, and it was difficult to make them compatible.

Japanese Patent Laid-Open No. 2003-041017 Japanese Patent Laid-Open No. 2014-051657 Japanese Patent Laid-Open No. 2017-125184 International Publication No. 2016/006578 International Publication No. 2014/148547

However, in the method of patent documents 1 and 3 mentioned above, when mechanical strength was low and conveying a polypropylene film and an adhesion film at high temperature, there existed a problem that wrinkles arise. In addition, in the method described in Patent Documents 2 and 4, there were problems such as high thermal shrinkage at high temperature, peeling from an adherend, or curling. Moreover, in the method of patent document 5, the rigidity of the film in high temperature was low, when conveying an adhesive film at high temperature, there existed a problem, such as a film extending in a flow direction, and width contraction becoming large.

Accordingly, an object of the present invention is to solve the above problems. That is, it is an object to provide a polypropylene film that has excellent mechanical strength at room temperature and high temperature despite low thermal shrinkage force, and can be suitably used as a release film under a high temperature environment.

In order to solve the above problems and achieve the object, the polypropylene film of the present invention has a thermal contraction force of 400 mN or less at 140° C. in the main alignment axis direction and in a direction orthogonal thereto, and the main alignment axis direction and orthogonal thereto It is characterized in that the Young's modulus in all directions is 1.8 GPa or more.

Although the polypropylene film of the present invention has low thermal shrinkage force, it has excellent mechanical strength at room temperature and high temperature, and can be suitably used as a release film under a high temperature environment.

The polypropylene film of the present invention has both a thermal contraction force of 400 mN or less at 140° C. in the direction of the main alignment axis and a direction orthogonal thereto, and a Young's modulus in both the direction of the main alignment axis and a direction orthogonal thereto of 1.8 GPa or more.

The thermal contraction force at 140° C. in the direction of the main orientation axis and the direction orthogonal thereto is more preferably all 350 mN or less, still more preferably all 100 mN or less, still more preferably all 95 mN or less, and most preferably all 30 mN or less. am. When the thermal contraction force at 140°C in the direction of the main orientation axis and in the direction perpendicular thereto exceeds 400 mN in at least one side, peeling or curling occurs from the adherend due to shrinkage when bonding to the adherend and passing through the heating process or there are cases where Although the lower limit of the thermal contraction force at 140 degreeC in the direction orthogonal to the main orientation axis direction is not specifically limited, Actually, about -100 mN is a lower limit. In addition, the thermal contraction force here means the thermal contraction force in width 4mm, The measurement can be performed by the method shown in an Example.

In the present invention, the principal orientation axis direction is 15°, 30°, 45°, 60°, 75°, 90°, When the Young's modulus is measured in each direction forming an angle of 105°, 120°, 135°, 150°, and 165°, it refers to the direction showing the highest value. Here, in the polypropylene film of this invention, "longitudinal direction" is a direction corresponding to the flow direction in a film manufacturing process (it may be referred to as "MD" hereafter), and "width direction" is an above-described film It is a direction (hereinafter, sometimes referred to as "TD") orthogonal to the flow direction in a manufacturing process. When a film sample is in the shape of a reel, a roll, etc., it can be said that the film winding direction is a longitudinal direction. On the other hand, in the case of a film in which it is not clear which direction corresponds to the flow direction in the film manufacturing process from the appearance of the film, for example, a line is drawn at 15° intervals based on an arbitrary straight line on the film plane. , a slit-shaped film piece is sampled parallel to each line, the Young's modulus is obtained with a tensile tester, and the direction in which the maximum Young's modulus is given is regarded as the direction of its main orientation axis. Although the details will be described later, when the sample width is less than 150 mm and the Young's modulus cannot be obtained with a tensile tester, the crystal orientation of the α crystal (110) plane of the polypropylene film by wide-angle X-rays is measured as follows, It is set as the film length and width direction based on the following judgment criteria. That is, X-rays are incident in a direction perpendicular to the film surface, and the crystal peak at 2θ = about 14° (α crystal (110) plane) is scanned in the circumferential direction, and the obtained diffraction intensity distribution has the highest diffraction intensity. The direction is set to the direction of the main orientation axis.

More preferably, all of the Young's modulus in the direction of the main alignment axis and in the direction orthogonal thereto are 2.0 GPa or more, and even more preferably all of the Young's modulus is 2.3 GPa or more. When the Young's modulus in the direction of the main alignment axis and in the direction orthogonal thereto is less than 1.8 GPa in at least one side, wrinkles may occur when adhesive coating is applied to a polypropylene film and drying the adhesive layer in a high-temperature oven. Although the upper limit of the Young's modulus in the direction of the main alignment axis and the direction orthogonal thereto is not particularly limited, substantially about 10 GPa is the upper limit.

In order to make the values of the thermal contraction force and Young's modulus at 140°C in the direction of the main alignment axis and the direction orthogonal thereto within the above ranges, the raw material composition of the film is in the range described later, and the film forming conditions are in the range described later, and particularly It is effective to use a raw material having a high melting point, with a low cold xylene soluble part, and to set the preheat roll temperature at the time of longitudinal stretching in the range to be described later, and to homogenize the crystalline state before stretching, and then perform high orientation stretching.

The polypropylene film of the present invention preferably has a temperature of 116° C. or higher, more preferably all 124° C. or higher, and still more preferably all of the temperatures when the heat shrinkage force in the main orientation axis direction and the direction orthogonal thereto is 20 mN or higher. are all 132°C or higher, most preferably all 142°C or higher. When the temperature when the thermal contraction force becomes 20 mN or more in at least one of the main orientation axis direction and the direction orthogonal thereto is less than 116 ° C. Curls may occur. Although the upper limit of the temperature when a thermal contraction force will be 20 mN or more is not specifically limited, About 160 degreeC is an upper limit substantially. In order to make the value of the temperature when the thermal contraction force is 20 mN or more within the above range, the raw material composition of the film is set to the range described later, and the film forming conditions are set to the range described later, particularly high crystallinity and low cold xylene soluble portion, It is effective to use a raw material with a high melting point, to set the preheat roll temperature during longitudinal stretching in the range described later, to equalize the crystal state before stretching, and to appropriately promote relaxation of the film in the heat treatment process after horizontal stretching .

In the polypropylene film of the present invention, the maximum point stress at 120° C. in the direction of the main alignment axis and the direction perpendicular thereto is preferably 80 MPa or more, more preferably 100 MPa° C. or more, and still more preferably all 120 MPa or more. am. When the maximum point stress at 120°C is less than 80 MPa in at least one of the direction of the main orientation axis and the direction orthogonal thereto, there is a case where wrinkles occur when adhesive coating is applied to a polypropylene film and drying the adhesive layer in a high-temperature oven have. Although the upper limit of maximum point stress is not specifically limited, Actually, about 300 MPa is an upper limit. In order to make the maximum point stress within the above range, the raw material composition of the film is set to the range described later, and the film forming conditions are set to the range described later, particularly high crystallinity, low cold xylene soluble part, and high melting point raw material is used; Moreover, it is preferable to make the preheat roll temperature at the time of longitudinal stretching in the range mentioned later, and to carry out high orientation stretching after making the crystal state before extending|stretching uniform. Moreover, it is preferable to make the heat processing temperature after lateral stretching and a relaxation rate into the ranges mentioned later, and not to relieve|moderate the orientation of a film more than necessary.

The polypropylene film of the present invention preferably has a maximum projection roughness St of at least one side of 2000 nm or more, more preferably 4000 nm or more, still more preferably 6000 nm or more. When St on both surfaces of a film is less than 2000 nm, the releasability at the time of peeling from a to-be-adhered body is insufficient, and a to-be-adhered body may deform|transform or break into a film. Although the upper limit of St is not specifically limited, About 30000 nm is an upper limit substantially. In order to make St into the above range, it is effective to set the raw material composition of the film in the range to be described later, and to make the film forming conditions in the range to be described later, and in particular to increase the casting temperature to high temperature to form β crystals in the unstretched film in the casting process. .

As for the polypropylene film of this invention, it is preferable that the thickness nonuniformity in the said main orientation axis direction is less than 6.0 %, More preferably, it is less than 4.0 %, More preferably, it is less than 2.0 %. When the thickness non-uniformity in the main orientation axis direction is 6.0% or more, it becomes difficult to join neatly at the time of joining with a to-be-adhered body, peeling from a to-be-adhered body, or air may mix. The lower limit of the thickness non-uniformity in the direction of the main alignment axis is not particularly limited, but substantially about 0.1% is the lower limit. In order to make the thickness non-uniformity in the main orientation axis direction within the above range, the raw material composition of the film is set to the range described later, and the film forming conditions are set to the range described later, and in particular, the preheating and stretching temperatures at the time of transverse stretching are adjusted to the ranges described later, , it is also effective to increase the lateral draw ratio.

The polypropylene film of the present invention preferably has a thermal contraction force of 95 mN or less at 140° C. in a direction orthogonal to the main orientation axis direction, more preferably 60 mN or less, still more preferably 30 mN or less, and most preferably 10 mN or less. is below. When the thermal contraction force at 140° C. in the direction perpendicular to the main alignment axis direction exceeds 95 mN, when bonding to the adherend and passing through the heating process, the case may be peeled off from the adherend or curled due to shrinkage have. Although the lower limit of the thermal contraction force at 140 degreeC in the direction orthogonal to the said main orientation axis direction is not specifically limited, Actually, about -100 mN is a lower limit. In order to make the thermal contraction force at 140° C. in the direction orthogonal to the main alignment axis direction within the above range, the raw material composition of the film is set to the range described later, and the film forming conditions are set to the range described later, especially the preheat roll at the time of longitudinal stretching It is effective to make temperature into the range mentioned later, and to carry out high orientation stretching after uniformizing the crystal state before extending|stretching. In addition, it is more effective to set the preheating temperature and the stretching temperature at the time of transverse stretching to the ranges described later, to increase the preheating temperature, to preheat the polypropylene film uniformly, and to perform high stress stretching at a temperature lower than the preheating temperature.

In the polypropylene film of the present invention, the value obtained by multiplying the Young's modulus (GPa) at 120° C. in the direction orthogonal to the main alignment axis direction by the thickness (μm) of the film is preferably 1.5 (GPa·μm) or more, and more preferably Preferably it is 3.0 (GPa-micrometer) or more, More preferably, it is 4.0 (GPa-micrometer) or more, Most preferably, it is 5.5 or more. The value obtained by multiplying the thickness of the film by the Young's modulus at 120°C in the direction perpendicular to the direction of the main alignment axis has a high correlation with the rigidity of the film under a high-temperature environment. When passing, the film in conveyance stretches in a flow direction, and the width contraction of a film may become large. The upper limit of the value obtained by multiplying the thickness of the film by the Young's modulus at 120°C in a direction orthogonal to the direction of the main alignment axis is not particularly limited, but substantially about 30 is the upper limit. In order to make the value obtained by multiplying the thickness of the film by the Young's modulus at 120°C in a direction orthogonal to the direction of the main alignment axis to be within the above range, the raw material composition of the film is in the range described later, and the film forming conditions are in the range described later, especially The preheating roll temperature at the time of longitudinal stretching shall be in the range described later, and after homogenizing the crystal state before stretching, high orientation stretching, preheating during transverse stretching, and stretching temperature are adjusted to the ranges described later, and uniformly preheated at a high temperature It is effective not to take too large a relaxation rate and not to relax an orientation too much to perform high orientation stretching at low temperature, and to not relax too much.

The polypropylene film of this invention has a laminated structure of two or more layers, and at least one layer is 50 mass % or more and 100 mass % of polypropylene whose cold xylene soluble part (CXS) is 3.5 % or less in 100 mass % of total of the said layer. It is preferable that it is a layer containing below, more preferable content is 70 mass % or more and 100 mass % or less, more preferable content is 90 mass % or more and 100 mass % or less, Most preferable content is 95 mass % or more and 100 mass % or less. Here, CXS refers to a polyolefin component dissolved in xylene when the sample is completely dissolved in xylene and then precipitated at room temperature, and is a component that is difficult to crystallize due to low stereoregularity or low molecular weight. It is thought that When many of these components are contained in resin, the thermal dimensional stability of a film may be inferior. Therefore, as for CXS of the polypropylene contained in the polypropylene film of this invention, 2.0 % or less is more preferable, and 1.5 % or less is still more preferable. It is a laminated structure of two or more layers, and when content of the polypropylene whose CXS in at least 1 layer is 3.5 % or less is less than 50 mass %, the mechanical strength in high temperature of a polypropylene film runs short. As a result, for example, when adhesive coating is applied to a polypropylene film and an adhesion layer is dried in high temperature oven, wrinkles may arise. In addition, in a laminated configuration of two or more layers, when at least one layer contains 50% by mass or more and 100% by mass or less of polypropylene having a CXS exceeding 3.5% in at least one layer, the thermal contraction force becomes large, and it joins with an adherend and passes through a heating step When it does, it may peel from a to-be-adhered body by shrinkage, or curl may generate|occur|produce. Although the lower limit of at least one layer of CXS is not specifically limited, About 0.1 % is a lower limit substantially. In order to make CXS into the said range, it is effective to make the raw material composition of a film into the range mentioned later, and to use the polypropylene raw material with especially low CXS.

The polypropylene film of the present invention is not particularly limited as to whether it has a single-layer structure or a laminated structure as long as it contains polypropylene, but as described above, the polypropylene film of the present invention has a laminated structure of two or more layers, and at least one layer is CXS It is preferable that it is a layer containing 50 mass % or more and 100 mass % or less of polypropylene which is 3.5 % or less. It is preferable that the layer containing 50 mass % or more and 100 mass % or less of polypropylene whose CXS is 3.5 % is the largest layer among each layer of laminated constitution. In particular, it is preferable that the inner layer of a three-layer structure is a layer containing 50 mass % or more and 100 mass % or less of CXS of 3.5 % or less polypropylene.

The polypropylene film of the present invention has a laminated configuration of two or more layers, and at least one layer is heated from 25°C to 250°C at 20°C/min by differential scanning calorimeter DSC, and then from 250°C to 25°C at 20°C/min. It is preferable that the crystallization peak temperature (Tc) when temperature-falling is 110 degreeC or more, More preferably, it is 112 degreeC or more, More preferably, it is 114 degreeC or more. Tc correlates with the ease of crystallization, and the higher the Tc, the easier it is to crystallize. The polypropylene film crystallizes to form spheroids when solidified on a cooling drum after melt extrusion. The higher the Tc, the more dense spherulites are produced in the unstretched sheet, and with it, the surface shape of the film after biaxial stretching also becomes finer. From a viewpoint of obtaining the surface with the processus|protrusion with which the releasability becomes favorable without making it transfer to a to-be-adhered body, and obtaining the refinement|miniaturization of Tc, it is so preferable that Tc is high. Although the upper limit of Tc is not specifically limited, About 125 degreeC is an upper limit substantially. In order to make Tc into the said range, it is effective to make the raw material composition of a film into the range mentioned later, and to use a branched polypropylene and polypropylene raw material with high molecular weight especially. In obtaining the value of Tc, it is necessary to separate the polypropylene film into each layer and evaluate each layer, but when it is difficult to separate into each layer, the film as a whole is evaluated, and the value is regarded as a representative value.

Although the thickness of the polypropylene film of this invention is adjusted suitably according to a use, and limitation in particular is not carried out, It is preferable from a viewpoint of handling property that they are 0.5 micrometer or more and 100 micrometers or less. In order to make use of these characteristics, the thickness is more preferably 1 µm or more and 40 µm or less, still more preferably 1 µm or more and 30 µm or less, and most preferably 6 µm or more and 30 µm or less. The thickness can be adjusted by the number of screw rotations of the extruder, the width of the unstretched sheet, the film forming speed, the draw ratio, and the like within a range that does not reduce other physical properties.

Next, although the raw material of the polypropylene film of this invention is demonstrated, it is not necessarily limited to this.

The polypropylene film of the present invention is not particularly limited as to whether it has a single-layer structure or a laminated structure as long as it contains polypropylene, but as described above, the polypropylene film of the present invention has a laminated structure of two or more layers, and at least one layer is CXS It is preferable that it is a layer containing 50 mass % or more and 100 mass % or less of polypropylene which is 3.5 % or less. In order to obtain a polypropylene film having such a layer (a layer containing 50% by mass or more and 100% by mass or less of polypropylene having a CXS of 3.5% or less), a raw material having a CXS of 3.5% or less (hereinafter, a polypropylene having a CXS of 3.5% or less as a raw material) is obtained. It is preferable to use the polypropylene raw material A). CXS of the polypropylene raw material A is more preferably 2.0 % or less, More preferably, it is 1.5 % or less. The content of the polypropylene raw material A is preferably 50 mass % or more, more preferably 70 mass % or more, still more preferably 90 mass % or more, when the layer containing the polypropylene raw material A is 100 mass %, 95 It is most preferable that it is mass % or more. In order to obtain a polypropylene raw material satisfying such CXS, a method of increasing the catalytic activity when obtaining a resin or a method of washing the obtained resin with a solvent or an olefin monomer itself can be used.

Moreover, as for the polypropylene raw material A, a viewpoint of intensity|strength or heat resistance to homopolypropylene is used preferably.

It is preferable that melting|fusing point of polypropylene raw material A is 155 degreeC or more, More preferably, 160 degreeC or more and 165 degreeC or more are still more preferable. When melting|fusing point is less than 155 degreeC, heat resistance is insufficient, and when it joins with a to-be-adhered body and passes through a heating process, it may peel from a to-be-adhered body or curl may arise by shrinkage|contraction.

As for the polypropylene raw material A, it is preferable that a mesopentad fraction is 0.94 or more, More preferably, it is 0.97 or more. The mesopentad fraction is an index indicating the stereoregularity of the crystal phase of polypropylene measured by nuclear magnetic resonance (NMR method). desirable. There is no particular restriction on the upper limit of the mesopentad fraction. In order to obtain a resin with high stereoregularity as described above, a method of washing the resin powder obtained with a solvent such as n-heptane, a method of selecting a catalyst and/or a cocatalyst, and a method of appropriately selecting a composition are preferably employed. .

Further, as the polypropylene raw material A, more preferably, the melt flow rate (MFR) is 1 to 10 g/10 min (230°C, 21.18 N load), more preferably 1 to 8 g/10 min (230° C., 21.18 N load). load), particularly preferably in the range of 4 to 8 g/10 min (230°C, 21.18 N load), from the viewpoints of film forming properties and film strength. In order to make melt flow rate (MFR) into the said value, the method of controlling an average molecular weight, molecular weight distribution, etc. are employ|adopted.

As polypropylene raw material A, the copolymerization component etc. by another unsaturated hydrocarbon may be contained in the range which does not impair the objective of this invention, and the polymer may be blended. As a monomer component constituting such a copolymerization component or a blend, for example, ethylene, propylene (in the case of a copolymerized blend), 1-butene, 1-pentene, 3-methylpentene-1, 3-methylbutene-1, 1 -Hexene, 4-methylpentene-1, 5-ethylhexene-1, 1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl- 2-norbornene etc. are mentioned. From the viewpoint of dimensional stability, the amount of copolymerization or blending is preferably less than 1 mol% in terms of copolymerization, and less than 10% by mass in terms of blending.

It is preferable that content of the ethylene component contained in the polypropylene raw material A is 10 mass % or less. More preferably, it is 5 mass % or less, More preferably, it is 3 mass % or less. Although crystallinity falls so that there is much content of an ethylene component, it is easy to improve transparency, when content of an ethylene component exceeds 10 mass %, intensity|strength may fall or heat resistance may fall and thermal contraction rate may deteriorate. In addition, the resin tends to deteriorate during the extrusion process, and fish eyes in the film are likely to occur in some cases.

To the polyolefin raw material used for the polypropylene film of the present invention, various additives such as a crystal nucleating agent, antioxidant, heat stabilizer, slip agent, antistatic agent, antiblocking agent, filler, viscosity You can also contain a regulator, a coloring inhibitor, etc.

Among these, selection of the type of antioxidant and the amount to be added is important from the viewpoint of bleed-out of the antioxidant. That is, as such an antioxidant, it is a phenol-type thing which has steric hindrance, and at least 1 sort(s) of it is a high molecular weight type thing of molecular weight 500 or more is preferable. Although various things can be mentioned as the specific example, For example, 2,6-di-t-butyl-p-cresol (BHT: molecular weight 220.4) together with 1,3,5-trimethyl-2,4,6-tris(3) ,5-di-t-butyl-4-hydroxybenzyl)benzene (for example, "Irganox" (registered trademark) 1330 manufactured by BASF: molecular weight 775.2) or tetrakis [methylene-3 (3,5-di-t-) It is preferable to use butyl-4-hydroxyphenyl) propionate] methane (for example, "Irganox" (trademark) 1010 by BASF Corporation: molecular weight 1177.7) etc. together. As for the total content of these antioxidants, the range of 0.03-1.0 mass % is preferable with respect to polyolefin raw material whole quantity. If there is too little antioxidant, the polymer may deteriorate in the extrusion process, resulting in coloration of the film or poor long-term heat resistance. When there are too many antioxidants, transparency may fall by the bleed-out of these antioxidants. A more preferable content is 0.05-0.9 mass %, Especially preferably, it is 0.1-0.8 mass %.

Moreover, it is preferable that the polypropylene film of this invention has at least 1 layer or more of layers containing branched polypropylene. When content of the branched polypropylene in the layer containing branched polypropylene resin makes the whole layer 100 mass %, 0.05-10 mass % is preferable. A dense and fine surface with a high crystallization peak temperature (Tc) of the polypropylene film, controlling the size of spheroids generated in the cooling process of the melt-extruded resin sheet to be small, and reducing the steep height difference of the surface irregularities of the film after biaxial stretching From a viewpoint of forming an unevenness|corrugation, the minimum of content of branched polypropylene resin becomes like this. More preferably, it is 0.5 mass % or more, More preferably, it is 1 mass % or more. On the other hand, the upper limit of content of branched polypropylene resin becomes like this. More preferably, it is 8 mass % or less, More preferably, it is 5 mass % or less.

Moreover, a crystal nucleating agent can be added to the polypropylene raw material used for the polypropylene film of this invention in the range which does not go against the objective of this invention. α tablet nucleating agent (dibenzylidene sorbitol, sodium benzoate, etc.), β tablet nucleating agent (1,2-hydroxystearate potassium, magnesium benzoate, N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide) Amide compounds, such as quinacridone compounds, etc.) etc. are illustrated. However, since excessive addition of the above-mentioned different type of nucleating agent may cause a decrease in transparency or strength due to a decrease in stretchability or void formation, etc., the amount added is usually 0.5% by mass or less, preferably 0.1% by mass or less, more preferably It is preferable to set it as 0.05 mass % or less.

It is preferable that the polypropylene film of this invention is biaxially stretched using the above-mentioned raw material. The biaxial stretching method is obtained by any of the inflation simultaneous biaxial stretching method, the stenter simultaneous biaxial stretching method, and the stenter sequential biaxial stretching method, but among them, film forming stability, thickness uniformity, high rigidity and dimensional stability of the film It is preferable to adopt a stenter successive biaxial stretching method in terms of controlling the

Next, although one aspect of the manufacturing method of the polypropylene film of this invention is demonstrated as an example, it is not necessarily limited to this.

First, 80 parts by mass of polypropylene raw material A and 20 parts by mass of branched polypropylene raw material are dry blended and supplied to a single screw extruder for layer B (base layer (II)), and polypropylene raw material A is added to layer A (surface layer (I)) ) is supplied to a single screw extruder for use, and melt extrusion is performed at 200 to 280°C, more preferably 220 to 280°C, still more preferably 240 to 270°C. Then, after removing foreign substances or modified polymers with a filter installed in the middle of the polymer tube, laminated with a multi-manifold type A-layer/B-layer/A-layer composite T die, and discharged on a casting drum, A-layer/B A laminated unstretched sheet having a layer structure of layer/layer A is obtained. In this case, the lamination thickness ratio is preferably in the range of 1/8/1 to 1/60/1. By setting it as the said range, at least 1 layer of a layer whose CXS is 3.5% or less, or a layer whose Tc is 112 degreeC or more is formed, and it can obtain the film excellent in heat resistance and mechanical strength at high temperature.

Further, the casting drum preferably has a surface temperature of 40 to 120°C, preferably 60 to 120°C, more preferably 80 to 110°C. Moreover, it is not cared also as a two-layer laminated structure of A-layer/B-layer. As a method of adhesion to the casting drum, any of an electrostatic application method, an adhesion method using the surface tension of water, an air knife method, a press roll method, an underwater casting method, etc. may be used, but air with good flatness and controllable surface roughness The knife method is preferred. The air temperature of the air knife is 40 to 100° C., and the blowing air velocity is preferably 130 to 150 m/s. Moreover, in order not to generate|occur|produce vibration of a film, it is preferable to adjust the position of an air knife suitably so that air may flow to a film forming downstream.

The obtained unstretched sheet|seat is introduce|transduced into a longitudinal stretch process. In the longitudinal stretching step, first, the unstretched sheet is brought into contact with a plurality of metal rolls maintained at a temperature of 10° C. or higher and 160° C. or lower, preferably 140° C. or higher and 158° C. or lower, more preferably 145° C. or higher and 155° C. or lower to preheat, After extending|stretching 4 to 8 times in the longitudinal direction between rolls provided with the circumferential speed difference, it cools to room temperature. The stretching temperature is 100°C or more and 150°C or less, preferably 100°C or more and 140°C or less, and more preferably 110°C or more and 130°C or less. By heating to a high temperature in the preheating step of longitudinal stretching, the β-crystal in the unstretched film transitions to the α-crystal, and the crystalline state in the polypropylene film can be homogenized. In addition, by setting the stretching temperature to be lower than the preheating temperature, stretching can be performed with a high stress. Thus, by uniformizing the crystal state in a polypropylene film in a longitudinal stretching process and extending|stretching at high stress, it is excellent in the mechanical strength at high temperature, and a polypropylene film with low thermal contraction force can be obtained. 3 times or more and 6 times or less are preferable, and, as for a draw ratio, 4 times or more and 5.5 times or less are still more preferable.

Then, the longitudinal uniaxially stretched film is guided by a tenter, the end of the film is gripped with a clip, preheated, and then transversely stretched 7 to 13 times in the width direction. At this time, by increasing the preheating temperature, uniformly preheating the polypropylene film, and stretching the polypropylene film under high stress at a temperature lower than the preheating temperature, a polypropylene film having excellent mechanical strength at high temperature and low thermal shrinkage can be obtained. From this, a preheating temperature is 165-180 degreeC, More preferably, it is 170-180 degreeC, More preferably, it is 173-180 degreeC. Moreover, the transverse stretching temperature is 155-170 degreeC, More preferably, it is 155-165 degreeC, More preferably, it is 155-160 degreeC.

In the subsequent heat treatment and relaxation treatment process, while tension is applied in the width direction with a clip and relaxed at a relaxation rate of 2 to 20%, more preferably 8 to 18%, and still more preferably 10 to 15%, 140 ℃ or more and less than 170 ℃, more preferably, heat-fixed at a temperature of 140 ℃ or more and less than 160 ℃, and guided to the outside of the tenter through a cooling process at 80 to 100 ℃ while holding the tension in the width direction with a clip , Release the clip of the film edge part, slit the film edge part in a winder process, and wind up the film product roll. When heat processing is performed at high temperature of 170 degreeC or more, the orientation of a polypropylene film may be relieve|moderated, and the fall of mechanical strength may be caused. In particular, the fall of the mechanical strength in a high temperature region becomes remarkable. In addition, when the relaxation treatment is performed at a relaxation rate of 20% or more, the orientation of the polypropylene film is relaxed, which may lead to a decrease in mechanical strength. In particular, the fall of the mechanical strength in a high temperature region becomes remarkable.

The polypropylene film obtained as described above can be used in various applications such as packaging films, surface protection films, process films, hygiene products, agricultural products, construction products, and medical products. , It can be used preferably as a process film and a release film, Especially preferably, it can use as a release film.

Next, the example in the case of using the polypropylene film of this invention as a coating base material for adhesion films (base film) is demonstrated. The polypropylene film of this invention can be set as the adhesive film which has an adhesive layer on the at least single side|surface.

The adhesive used for the adhesive layer in the adhesive film of this invention is not specifically limited, A rubber type, a vinyl polymerization type, a condensation polymerization type, a thermosetting resin type, a silicone type, etc. can be used. Among them, examples of the rubber-based pressure-sensitive adhesive include a butadiene-styrene copolymer system, a butadiene-acrylonitrile copolymer system, and an isobutylene-isoprene copolymer system. As a vinyl polymerization type adhesive, an acryl type, a styrene type, a vinyl acetate-ethylene copolymer type|system|group, a vinyl chloride-vinyl acetate copolymer type|system|group, etc. are mentioned. Moreover, as an adhesive of a condensation polymerization system, a polyester system is mentioned. Moreover, an epoxy resin type, a urethane resin type, etc. are mentioned as a thermosetting resin type adhesive.

Among these, it is excellent in transparency, and when a weather resistance, heat resistance, heat-and-moisture resistance, adhesiveness to a base material, etc. are considered, an acrylic adhesive is used suitably. As a specific example of such an acrylic pressure-sensitive adhesive, "SKdyne" (registered trademark) 1310, 1435, SKdyne 1811L, SKdyne 1888, SKdyne 2094, SKdyne 2096, SKdyne 2137, SKdyne 3096, SKdyne 1852, etc. manufactured by Soken Chemical Co., Ltd. are suitable examples. can be heard

In addition, it is preferable to use a curing agent together with the above-described acrylic pressure-sensitive adhesive. Specific examples of the curing agent include, in the case of isocyanate, toluene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, di Phenylmethane-4-4'-diisocyanate, diphenylmethane-2-4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4-4 '-diisocyanate, diskiurohexylmethane-2-4'-diisocyanate, lysine isocyanate, etc. are mentioned. The mixing ratio of a hardening|curing agent is 0.1-10 mass parts with respect to 100 mass parts of adhesives, Preferably it is 0.5-5 mass parts. When it is less than 0.1 mass part, hardening of an adhesive layer in a drying furnace will become inadequate, and a tear may generate|occur|produce. When it exceeds 10 parts by mass, the surplus curing agent may migrate to the substrate or may be gasified at a high temperature to cause contamination.

In addition, according to the material of a to-be-adhered body (glass or a functional film), you may add and mix|blend an antioxidant, a ultraviolet absorber, a silane coupling agent, a metal deactivator, etc. to an acrylic adhesive suitably.

As for the adhesion film using the polypropylene film of this invention, it is preferable that the thickness d of an adhesion layer is 2.0 micrometers or less. More preferably, it is 1.5 micrometers or less, More preferably, it is 1.0 micrometer or less. When the thickness d of an adhesion layer exceeds 2.0 micrometers, the slipperiness|lubricacy of the back surface of a base film and the surface of an adhesion layer may deteriorate, and winding-up may become difficult. Moreover, drying of the adhesion layer in a drying furnace may become inadequate, and tearing may generate|occur|produce. Tear-off is after coating the solution of the adhesive layer on one side of the base film, drying and curing in a drying furnace, winding the adhesive film of the present invention in a roll shape without intervening a release film, and then removing the adhesive film during use When unwinding, it points out the phenomenon to which a part of adhesion layer migrates to the back surface of a base film. A well-known technique can be used for the method of making the thickness of an adhesion layer into the said range, and it is controllable by solid content concentration of the solution of an adhesion layer, or coating thickness adjustment in various coating methods. When the thickness of the pressure-sensitive adhesive layer is too thin, stable coating may be difficult, or the adhesive force may not be adhered to the adherend due to too low a thickness, so about 0.1 µm is the lower limit.

It is preferable that the 180 degree peeling force after bonding the adhesive film using the polypropylene film of this invention to an acrylic board is 200 mN/25 mm or less. The peeling force is more preferably 100 mN/25 mm or less, still more preferably 80 mN/25 mm or less. When peeling force exceeds 200 mN/25 mm, the slipperiness|lubricacy of the back surface of a base film and the surface of an adhesion layer deteriorates, the case where winding-up becomes difficult, or tearing may generate|occur|produce. In order to make peeling force into the said range, it is effective to make the composition and thickness of an adhesive layer into the range mentioned later, and to make the raw material composition and film forming conditions of a film into the range mentioned later, and to control the surface roughness of a base film. If the peeling force is less than 10 mN/25 mm, the lower limit is about 10 mN/25 mm since the adhesive film may peel during conveyance after bonding with the adherend.

Next, although the manufacturing method of an adhesive layer is demonstrated, it is not necessarily limited to this.

First, a coating agent for an adhesive layer is prepared. The coating agent can be used by dissolving additives, such as the adhesive and hardening|curing agent mentioned above in a solvent. The solvent can be appropriately adjusted and used according to the drying temperature in the coater or the viscosity of the coating agent. Specific examples include methanol, ethanol, isopropyl alcohol, n-butanol, tert-butanol, ethylene glycol monomethyl ether, 1-methoxy-2 -At least one solvent selected from propanol, propylene glycol monomethyl ether, cyclohexanone, toluene, ethyl acetate, butyl acetate, isopropylacetone, methyl ethyl ketone, methyl isobutyl ketone, diacetyl acetone, and acetyl acetone is used. can

Although the solid content concentration in a coating agent is suitably selected according to the viscosity of a coating agent, or the thickness of an adhesion layer, it is preferable that it is 5-20 mass %.

Next, the base film mentioned above is conveyed to a coater, and the coating agent for adhesion layers is coated. Here, the surface on which the pressure-sensitive adhesive layer is coated may be any surface of the base film, but it is preferable to improve the wettability with the coating agent by pretreatment such as corona treatment on the coated surface in advance. On the other hand, in order to improve releasability, it is preferable not to perform pretreatment, such as corona treatment, on the back surface of a base film. The coating method (coating method) is not particularly limited, and conventional coating methods such as a metabar method, a doctor blade method, a gravure method, a die method, a knife method, a reverse method, and a dip method can be adopted. However, as described above, the thickness of the adhesive layer is a thin film of 2.0 μm or less, and the gravure method or the reverse method is preferable from the viewpoint of stably obtaining the coating layer of the thin film.

After coating the coating agent for adhesive layers on a base film, it guides to a drying furnace, removes the solvent in a coating agent, and obtains an adhesive film. Although the drying temperature here is suitably set according to the heat resistance of a base film, and the boiling point of a solvent, it is preferable that it is 60-170 degreeC. If it is less than 60 degreeC, hardening of an adhesive layer may not fully advance and tearing may generate|occur|produce. When it exceeds 170 degreeC, a base film may deform|transform and planarity may deteriorate. In addition, the drying time is preferably 15 to 60 seconds. If it is less than 15 seconds, hardening of an adhesive layer may not fully advance and tearing may generate|occur|produce. When it exceeds 60 second, since productivity will fall, it is unpreferable.

The adhesion film after drying is wound up with a winder, without bonding a release film etc. to the adhesion surface, and an adhesion film roll is obtained. Since the adhesive film of the present invention has the above-described configuration, hardening of the adhesive layer is sufficiently advanced, and the slip property of the back surface of the base film and the surface of the adhesive layer is also good, so even if it is wound without intervening a release film, tearing or winding is performed. There is no problem, such as generation|occurrence|production of wrinkles, and the adhesive film roll with good quality can be obtained.

The adhesive film of the present invention obtained as described above can be used in various applications such as packaging films, surface protection films, process films, hygiene products, agricultural products, construction products, and medical products. It can be used suitably as a protective film and a process film.

Moreover, since the polypropylene film of this invention is excellent in heat resistance and quality, it can use suitably as a release film which requires very high quality, such as an optical member and a semiconductor manufacturing process.

Example

Hereinafter, the present invention will be described in detail by way of Examples. In addition, the characteristic measured and evaluated by the following method.

(1) Film thickness

It measured using the micro thickness meter (made by Anritsu Corporation). The film was sampled at 10 cm square, arbitrarily measured at 5 points, and the average value was obtained.

(2) Heat shrinkage force, the temperature when the heat shrinkage force becomes 20mN or more

Using TMA (manufactured by SII Nanotechnology Co., Ltd./model TMA/SS6100), the heat shrinkage force curve in the measurement direction (the main orientation axis direction and the direction orthogonal thereto) was measured under the following conditions.

(a) Sample: width 4 mm x length 20 mm

(b) Temperature program: Raise the temperature from 30°C to a heating rate of 10°C/min

<Heat shrinkage force>

The heat shrinkage force (mN) at 140°C was read from the heat shrinkage force curve. The measurement was performed 3 times, and the average was calculated|required.

<Heat shrink start temperature>

In the thermal contraction force curve, the temperature when the thermal contraction force becomes 20 mN during the temperature increase process was read. The measurement was performed 3 times, and the average was calculated|required.

(3) Young's modulus

The Young's modulus was measured at 23 degreeC and 65 %RH using the film elongation measuring apparatus (AMF/RTA-100) by the Orientec Corporation. The sample was cut into a size of measuring direction (main orientation axis direction and a direction orthogonal thereto): 25 cm, a direction perpendicular to the measurement direction: 1 cm, stretched with an original length of 100 mm and a tensile rate of 300 mm/min, and Young's modulus was measured according to the method specified in JIS-Z1702 (1994).

(4) Young's modulus at 120°C

The Young's modulus at 120 ° C., using a film elongation measuring device (AMF/RTA-100) manufactured by Orientec Co., Ltd., put in an oven heated to 120 ° C., heated for 1 minute, and then the tensile rate was set to 300 mm /min, the film was subjected to a tensile test. The sample was cut to a size of 25 cm in the measurement direction (direction orthogonal to the main orientation axis): 1 cm in the direction perpendicular to the measurement direction, and stretched at an original length of 100 mm and a tensile rate of 300 mm/min, JIS-Z1702 (1994). ) was measured according to the method stipulated in

(5) Maximum point stress at 120°C

The maximum point stress at 120 ° C., using a film elongation measuring apparatus (AMF/RTA-100) manufactured by Orientec Co., Ltd., was put in an oven heated to 120 ° C., and after heating for 1 minute, the tensile rate was determined The tensile test of the film was done at 300 mm/min. The load value at breakage of the sample is read, and the value divided by the cross-sectional area (film thickness x width (10 mm)) of the sample before the test is calculated as the stress of breaking strength, and the measurement is performed 5 times for each sample, and the average value is evaluated. was done. In addition, as the film thickness used for calculating the breaking strength, the value measured in (1) above was used.

(6) Maximum asperity roughness (St)

The measurement was performed using Ryoka System VertScan2.0 R5300GL-Lite-AC, and the surface shape was obtained by surface correction of the shooting screen by polynomial quaternary approximation with the attached analysis software. In addition, maximum protrusion roughness St shows the difference between the height maximum value (Peak) and height minimum value (Valley) in a measurement area|region. Measurement conditions are as follows. Measurement was performed on both surfaces of the film at n = 3 (number of measurements = 3 times), and the average value of each surface was obtained, thereby employing as St of each surface. In addition, the value of the larger one is described in a table|surface among the values of St of both surfaces of a film.

Manufacturer: Ryoka System, Ltd.

Device Name: VertScan2.0 R5300GL-Lite-AC

Measurement conditions: CCD camera SONY HR-57 1/2 inch

Objective Lens: 5x

Medium Lens: 0.5x

Wavelength filter: 530nm white

Measurement mode: Wave

Measurement software: VS-Measure Version5.5.1

Analysis software: VS-Viewer Version5.5.1

Measurement area: 1.252 mm x 0.939 mm.

(7) thickness unevenness

A polypropylene film was prepared, the film was cut out to a width of 10 mm, and 20 points were measured at intervals of 50 mm in the main orientation axis direction. The average value of the obtained 20 points of data was obtained, and the difference (absolute value) between the maximum value and the minimum value was obtained, and the value obtained by dividing the absolute value of the difference between the minimum value and the maximum value by the average value was defined as the thickness non-uniformity in the main orientation axis direction of the film. In addition, the measurement was performed using the contact-type Anritsu Co., Ltd. electron micrometer (K-312A type) in the atmosphere of 23 degreeC 65 %RH.

(8) crystallization peak temperature (Tc)

Using a differential scanning calorimeter (Seiko Instruments Co., Ltd. EXSTAR DSC6220), the temperature was raised from 25° C. to 250° C. at 20° C./min for each layer of 3 mg polypropylene film in a nitrogen atmosphere, and held for 5 minutes. Then, it temperature-falls from 250 degreeC to 25 degreeC at 20 degreeC/min. The peak temperature of the exothermic curve obtained at the time of this temperature fall was made into the crystallization temperature (Tc) of a polypropylene film. In addition, when several peak temperature could be observed, the highest temperature in the area|region of 80 degreeC - 130 degreeC was made into the crystallization temperature (Tc) of a polypropylene film.

(9) Curl evaluation after heating

A polypropylene film and a 40 µm thick "Zeonoa Film" (registered trademark) manufactured by Nippon Zeon Co., Ltd. were sampled in a 100 mm wide and 100 mm long square, and the A side of the polypropylene film and the "Zeonoa Film" were They are overlapped so as to be in contact with each other, sandwiched between two acrylic plates (width 100 mm, length 100 mm), a load of 2 kg is applied, and after standing in an atmosphere of 23° C. for 1 hour, heated in an oven at 120° C. for 1 hour, and joined. A sample was taken. The Zeonoa film side was placed on the floor, and the height of the curled bonding sample was measured regularly, and the following criteria were evaluated.

S: The height of the curled joint sample is less than 5 mm.

A: The height of the curled bonding sample is 5 mm or more and less than 10 mm.

B: The height of the curled bonding sample is 10 mm or more and less than 15 mm.

C: The height of the curled bonding sample is 15 mm or more.

(10) Planarity of an adhesive film having an adhesive layer

The adhesive film having a 500 mm width adhesive layer wound on the core is unwound by 1 m, and uniformly 1 kg / m, and 3 kg without pre-tension (the state dangling in the vertical direction by the weight of the film) and the entire width of the film. A tension of /m was added, and the presence or absence of areas with poor flatness such as wrinkles or dents was visually confirmed.

S: There is no location of flatness defect in pre-tension.

A: Points with poor flatness are seen in pre-tension, and disappears in tension of 1 kg/m width.

B: Points with poor planarity are seen with a tension of 1 kg/m width, and disappearing with a tension of 3 kg/m width.

C: The point where the flatness defect does not disappear even with a tension of 3 kg/m width.

(9) Width shrinkability of adhesive film having adhesive layer

After coating the coating agent for the adhesion layer on the polypropylene film of 500 mm width, it guide|induced to a 100 degreeC drying furnace, conveyed with the tension|tensile_strength of 200N for 30 second, the solvent in the coating agent was removed, and the adhesive film was obtained. The width of the polypropylene film and the width of the adhesive film were measured with a maser, and the width shrinkage was calculated based on the following formula.

Width shrinkage (%) = (500-adhesive film width)/500×100

Based on the calculated width contraction rate, the following references|standards evaluated.

S: Width contraction rate is less than 0.5 %.

A: Width contraction rate is 0.5 % or more and less than 1.0 %.

B: Width contraction rate is 1.0 % or more and less than 2.0 %.

C: Width contraction rate is 2.0 % or more.

(Example 1)

As a raw material for surface layer (I), 98.5 mass parts of Sumitomo Chemical Co., Ltd. homopolypropylene raw material A (MFR: 7.5 g/10 min, melting|fusing point: 163 degreeC, CXS: 1.0%), and Ziegler-Natta catalyst type branched chain 1.5 parts by mass of dry blend of polypropylene raw material B (Profax PF-814) is fed to a single screw extruder for the surface layer (I) layer, and as a raw material for the inner layer (II), homopolypropylene manufactured by Prime Polymer Co., Ltd. Raw material C (MFR: 4.0 g/10 min, melting point: 166° C., CXS: 1.7%) 98.5 parts by mass and 1.5 parts by mass of the branched polypropylene B are dry blended, and a single screw extruder for the inner layer (II) layer is supplied to, melt extrusion is performed at 260 ° C., and foreign matter is removed with a sintered filter of 20 µm cut, and then laminated at a thickness ratio of 1/10/1 with a feed block type A/B/A composite T die, 102 ° C It was discharged to the casting drum in which the furnace surface temperature was controlled, and it was made to closely_contact|adhere to the casting drum with an air knife, and the unstretched sheet|seat was obtained. Subsequently, the sheet was preheated to 155° C. using a ceramic roll, and stretched 4.0 times in the longitudinal direction of the film between the rolls at 148° C. provided with a circumferential speed difference. Next, the tenter type stretching machine is introduced by gripping the end with a clip, preheated at 180° C. for 5 seconds, stretched 9.6 times at 170° C., and heat-treated at 167° C. while providing 14% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Example 2)

Prime Polymer Co., Ltd. homopolypropylene raw material D (MFR: 3.0 g/10 min, melting point: 164° C., CXS: 3.3%) 90 parts by mass, Mitsui Chemicals Co., Ltd. 4-methyl-1-pentene polymer 10 parts by mass of "MX004" (melting point: 230 ° C.) is supplied from the metering hopper to the twin screw extruder so that 10 parts by mass are mixed in this ratio, melt-kneaded at 260 ° C., discharged from the die in the form of strands, and cooled in a water bath at 25 ° C. It solidified and cut into chips to obtain a polypropylene raw material (1). As a raw material for the surface layer (I), 98 parts by mass of the homopolypropylene raw material C and 2 parts by mass of the polypropylene raw material (1) are dry blended, and supplied to a single screw extruder for the surface layer (I) layer, and the inner layer ( As a raw material for II), 98.5 parts by mass of the homopolypropylene raw material C and 1.5 parts by mass of the branched polypropylene raw material B are dry blended, and supplied to a single-screw single screw extruder for the inner layer (II) layer, at 260° C. After melt extrusion and removal of foreign matter with a sintered filter of 20 μm cut, it was laminated with a feed block type A/B/A composite T die at a thickness ratio of 1/12/1, and the surface temperature was controlled at 93° C. It was discharged to the drum, and it was made to closely_contact|adhere to the casting drum with an air knife, and the unstretched sheet|seat was obtained. Subsequently, the sheet was preheated to 153°C using a ceramic roll, and stretched 4.9 times in the longitudinal direction of the film between rolls at 128°C provided with a circumferential speed difference. Next, the tenter-type stretching machine is introduced by gripping the end with a clip, preheated at 179°C for 5 seconds, stretched 9.5 times at 173°C, and heat-treated at 148°C while providing 11% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Example 3)

As a raw material for the surface layer (I), 98 parts by mass of the homopolypropylene raw material A and 2 parts by mass of the polypropylene raw material (1) are dry blended, and supplied to a single-screw single screw extruder for the surface layer (I) layer, and the inner layer ( As a raw material for II), 70 parts by mass of the homopolypropylene raw material C and 30 parts by mass of the homopolypropylene raw material A are dry blended, fed to a single screw extruder for the inner layer (II) layer, and melted at 250° C. After extruding and removing foreign substances with a sintered filter having a cut of 20 µm, it was laminated with a feed block type A/B/A composite T die at a thickness ratio of 1/8/1, and the surface temperature was controlled at 58 ° C. was discharged to, and was brought into close contact with the casting drum with an air knife to obtain an unstretched sheet. Subsequently, the sheet was preheated to 144°C using a ceramic roll, and stretched 4.4 times in the longitudinal direction of the film between rolls at 138°C with a difference in circumferential speed. Next, the tenter type stretching machine is introduced by gripping the end with a clip, preheated at 176°C for 5 seconds, stretched 8.8 times at 167°C, and heat-treated at 163°C while giving 9% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Example 4)

As a raw material for the surface layer (I), 95.7 parts by mass of the homopolypropylene raw material D, 2.3 parts by mass of the branched polypropylene raw material B, and 2 parts by mass of the polypropylene raw material (1) are dry blended for the surface layer (I) layer is supplied to a single screw extruder of a single screw, and as a raw material for the inner layer (II), 97.7 parts by mass of the homopolypropylene raw material D and 2.3 parts by mass of the branched polypropylene raw material B are dry blended for the inner layer (II) layer It is supplied to a single screw extruder, melt-extruded at 250° C., and foreign matter is removed with a sintered filter having a cut of 20 μm, followed by a feed block type A/B/A composite T die at a thickness ratio of 1/10/1. It laminated|stacked, it discharged to the casting drum which controlled the surface temperature at 110 degreeC, it was made to adhere to the casting drum with an air knife, and the unstretched sheet|seat was obtained. Subsequently, the sheet was preheated to 159°C using a ceramic roll, and stretched 4.1 times in the longitudinal direction of the film between the rolls at 125°C provided with a circumferential speed difference. Next, the tenter type stretching machine is introduced by gripping the end with a clip, preheated at 180° C. for 5 seconds, stretched 10.2 times at 175° C., and heat-treated at 140° C. while providing 14% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Example 5)

As a raw material for the surface layer (I), 98.5 parts by mass of the homopolypropylene raw material C and 1.5 parts by mass of the branched polypropylene raw material B are dry blended, and supplied to a single-screw single screw extruder for the surface layer (I) layer, and the inner layer As a raw material for (II), 100 parts by mass of the homopolypropylene raw material C is supplied to a single-screw single screw extruder for the inner layer (II) layer, melt extrusion is performed at 250° C., and foreign matter is removed by a sintered filter having a cut of 20 μm. After removal, it is laminated at a thickness ratio of 1/10/1 with a feed block type A/B/A composite T die, discharged to a casting drum whose surface temperature is controlled at 65° C., and adhered to the casting drum with an air knife. , an unstretched sheet was obtained. Subsequently, the sheet was preheated to 152°C using a ceramic roll, and stretched 4.6 times in the longitudinal direction of the film between rolls at 132°C provided with a circumferential speed difference. Next, the tenter type stretching machine is introduced by gripping the end with a clip, preheated at 177° C. for 5 seconds, stretched 6.8 times at 169° C., and heat-treated at 170° C. while giving 16% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Example 6)

As a raw material for the surface layer (I), 95 parts by mass of the homopolypropylene raw material D and 5 parts by mass of a metallocene catalyst-based branched polypropylene raw material (WAYMAX MFX3 manufactured by Nippon Polypro Co., Ltd.) were dry blended to prepare the surface layer (I) layer 100 parts by mass of the homopolypropylene raw material D as a raw material for the inner layer (II) is fed to a single screw extruder and fed to a single screw extruder for the inner layer (II) layer, and melt extrusion is performed at 250 ° C. , after removing foreign substances with a sintered filter with a cut of 20 μm, stacked with a feed block type A/B/A composite T die at a thickness ratio of 1/10/1, and discharged to a casting drum whose surface temperature is controlled at 55° C. , it was made to closely_contact|adhere to the casting drum with an air knife, and the unstretched sheet|seat was obtained. Subsequently, the sheet was preheated to 146° C. using a ceramic roll, and stretched 4.4 times in the longitudinal direction of the film between rolls at 133° C. provided with a circumferential speed difference. Next, the tenter-type stretching machine is introduced by gripping the end with a clip, preheated at 176°C for 5 seconds, stretched 7.8 times at 166°C, and heat-treated at 153°C while providing 11% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound up around the core, and the 7-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 1)

A polypropylene resin (MFR: 2.0 g/10 min) having a copolymer composition of 98.4 parts by mass of a propylene component and 1.6 parts by mass of an ethylene component is supplied to a single screw extruder, extruded from a T-die at 280 ° C. After being cooled and solidified on a cold roll, 4.4 times longitudinally stretched by a heating roll stretching machine set at 141 ° C., then 9.2 times horizontally stretched by a tenter stretching machine set at 162 ° C. After transverse stretching, heat treatment at 170 ° C., 30 A ㎛ polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 2)

"Novatech SA4L" (MFR=5.0/10 min) manufactured by Nippon Polypro Co., Ltd. was supplied to a single screw extruder, extruded from a T-die at 250°C into a sheet, and cooled and solidified with a cooling roll at 30°C. Then, it is longitudinally stretched 4.5 times at 135° C., then both ends are clamped with clips, guided into a hot air oven, preheated at 169° C., stretched transversely at 8.2 times at 160° C., and continuously relaxed at a relaxation rate of 6.7% 168 It was heat-treated at ℃ to obtain a polypropylene film of 4㎛. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 3)

75 parts by mass of the homopolypropylene raw material D, 25 parts by mass of calcium carbonate particles (manufactured by Sankyo Sehun Co., Ltd., 2480K, particle diameter: 6 µm) are dry blended, and fed to a single screw melt extruder for inner layer (II), The homopolypropylene raw material D is supplied to a single-axis melt extruder for the surface layer (I), melt-extruded at 240° C., and foreign matter is removed with a sintered filter having an 80 μm cut, and then a feed block type B/A/B It laminated|stacked at the thickness ratio of 1/50/1 with composite T-die, it discharged to the cast drum which controlled the surface temperature at 30 degreeC, and obtained the cast sheet. Next, it preheated to 140 degreeC using several ceramic rolls, and extended|stretched 4.6 times in the longitudinal direction of the film. Next, the tenter type stretching machine was introduced by gripping the end with a clip, and after preheating at 165°C for 3 seconds, it was stretched 8.0 times at 160°C. In the subsequent heat treatment step, heat treatment is performed at 160° C. while applying 10% relaxation in the width direction, and then, through a cooling step at 130° C., it is guided to the outside of the tenter, the clip at the end of the film is released, and the film is placed on the core. It wound up and obtained the 25-micrometer-thick polypropylene film. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 4)

99.7 parts by mass of the homopolypropylene raw material A, 0.3 parts by mass of N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide (New Nippon Rica Co., Ltd., NU-100), which is a β-tablet nucleating agent, In addition, the antioxidants, IRGANOX (registered trademark) 1010 and IRGAFOS (registered trademark) 168 manufactured by Ciba Specialty Chemicals, are supplied from a metering hopper to the twin-screw extruder so that 0.1 parts by mass each are mixed in this ratio, and melt-kneaded at 300 ° C., Discharged from the die in the form of strands, solidified by cooling in a water bath at 25°C, and cut into chips to obtain a polypropylene raw material (2).

The homopolypropylene raw material D is fed to a single-screw melt extruder for the inner layer (II) layer, and the polypropylene raw material (2) is fed to a single-screw melt extruder for the surface layer (I) layer, and melt extrusion is performed at 240 ° C. , After removing foreign substances with a sintered filter of 60 µm cut, it was laminated with a feed block type A/B composite T die at a thickness ratio of 8/1, and discharged to a cast drum whose surface temperature was controlled at 90° C. to obtain a cast sheet . Then, it preheated at 125 degreeC using several ceramic rolls, and extended|stretched 4.6 times in the longitudinal direction of the film. Next, the tenter type stretching machine was introduced by gripping the end with a clip, and after preheating at 165°C for 3 seconds, it was stretched 8.0 times at 160°C. In the subsequent heat treatment step, heat treatment is performed at 160° C. while applying 10% relaxation in the width direction, and then, it is guided to the outside of the tenter through a cooling step at 130° C., the clip at the end of the film is released, and the film is applied to the core. It wound up and obtained the 15-micrometer-thick polypropylene film. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 5)

As a raw material for the surface layer (I), 98.5 parts by mass of the homopolypropylene raw material A and 1.5 parts by mass of the branched polypropylene raw material B are dry blended, and supplied to a single-screw single screw extruder for the surface layer (I) layer, and the inner layer As a raw material for (II), 98.5 parts by mass of the homopolypropylene raw material C and 1.5 parts by mass of the branched polypropylene raw material B are dry blended, and supplied to a single-screw single screw extruder for the inner layer (II) layer, 250 Perform melt extrusion at ° C, remove foreign substances with a sintered filter of 20 μm cut, and then laminate with a feed block type A/B/A composite T die at a thickness ratio of 1/10/1, and control the surface temperature at 35 ° C. It was discharged to one casting drum, and it was made to closely_contact|adhere to the casting drum with an air knife, and the unstretched sheet|seat was obtained. Subsequently, the sheet was preheated to 153° C. using a ceramic roll, and stretched 3.7 times in the longitudinal direction of the film between rolls at 148° C. provided with a circumferential speed difference. Next, the tenter type stretching machine is introduced by gripping the end with a clip, preheated at 180° C. for 5 seconds, stretched 7.2 times at 178° C., and heat-treated at 170° C. while giving 16% relaxation in the width direction, and then It guide|induced to the outside of a tenter through a 100 degreeC cooling process, the clip of the film edge part was released, the film was wound around the core, and the 25-micrometer-thick polypropylene film was obtained. Table 1 shows the physical properties and evaluation results of the obtained film.

(Comparative Example 6)

As a linear polypropylene, the mesopentad fraction is 98.5%, and the melt mass flow rate (MFR) is 2.6 g/10 min. 100 parts by mass of a polypropylene resin manufactured by Prime Polymer Co., Ltd., a branched polypropylene resin manufactured by Basell Corporation (high 0.5 parts by mass of melt tension polypropylene Profax PF-814 mesopentad fraction 91.0%) is blended, fed to an extruder at a temperature of 250° C., and melt-extruded from a T-slit die at a resin temperature of 250° C. into a sheet, and the The molten sheet was cooled and solidified on a casting drum having a diameter of 1 m maintained at 90° C. at an air knife temperature of 90° C. and an air velocity of 140 m/s. Next, the sheet was gradually preheated to 140°C, then maintained at a temperature of 145°C, passed between rolls provided with a circumferential speed difference, and stretched 4.8 times in the longitudinal direction. At that time, the stretching part was performed by supplementing the amount of heat by using a radiation heater (output 3.5 kW). Subsequently, the film was guided by a tenter, stretched 10 times in the width direction at a stretching temperature of 160° C., and then relaxed in three steps in the width direction at a total relaxation rate of 23% (12.0% in the first stage, the second stage in the second stage) is 9.0%, and the third stage is 3.9%). It heat-processed at the heat setting temperature of 150 degreeC, and the cooling temperature of 140 degreeC, and it quenched for 5 second at room temperature after that, and obtained the biaxially-oriented polypropylene film whose film thickness is 3.0 micrometers. Table 1 shows the physical properties and evaluation results of the obtained film.

In addition, the "direction orthogonal to the main alignment axis" in the table means a direction orthogonal to the main alignment axis direction.

As described above, the polypropylene film of the present invention can be used in various applications such as packaging films, release films, process films, hygiene products, agricultural products, construction products, and medical products. In particular, since it is excellent in heat resistance, mechanical strength, releasability, and quality, it can be preferably used as a release film or a process film that passes through a high-temperature process after bonding to an adherend.

Claims (12)

A polypropylene film, wherein both the thermal contraction force at 140° C. in the direction of the main alignment axis and the direction orthogonal thereto are 400 mN or less, and the Young's modulus in both the direction of the main alignment axis and the direction orthogonal thereto is 1.8 GPa or more. The polypropylene film according to claim 1, wherein the temperature in the direction of the main alignment axis and the direction orthogonal thereto when the thermal contraction force is 20 mN or more is 116°C or more. The polypropylene film according to claim 1 or 2, wherein the maximum point stress at 120°C in the direction of the main alignment axis and the direction orthogonal thereto is 80 MPa or more. The polypropylene film according to any one of claims 1 to 3, wherein the maximum protrusion roughness St of at least one side is 2000 nm or more. The polypropylene film according to any one of claims 1 to 4, wherein the thickness non-uniformity in the main orientation axis direction is less than 6.0%. The polypropylene film according to any one of claims 1 to 5, wherein the thermal contraction force at 140°C in a direction orthogonal to the main alignment axis direction is 95 mN or less. The value obtained by multiplying the Young's modulus (GPa) at 120°C in a direction orthogonal to the main alignment axis direction by the thickness (μm) of the film is 1.5 (GPa·μm) according to any one of claims 1 to 6 ) or more, a polypropylene film. The polypropylene film according to any one of claims 1 to 7, wherein the thickness of the film is at least 6 μm. The composition according to any one of claims 1 to 8, wherein at least one layer contains 50% by mass or more and 100% by mass or less of polypropylene having a cold xylene soluble part (CXS) of 3.5% or less. layered, polypropylene film. 10. The method according to any one of claims 1 to 9, wherein it has a laminated configuration of two or more layers, wherein at least one layer is heated from 25°C to 250°C at 20°C/min using a differential scanning calorimeter DSC, and then from 250°C The polypropylene film whose crystallization peak temperature (Tc) when temperature-falling at 20 degreeC/min to 25 degreeC is 110 degreeC or more. The adhesive film which has an adhesive layer on at least single side|surface of the polypropylene film in any one of Claims 1-10. The release film using the polypropylene film in any one of Claims 1-10.