Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/10—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial
  • B29C55/12—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets multiaxial biaxial
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins

Definitions

• the present invention relates to biaxially oriented polypropylene films and laminates thereof.
• biaxially oriented polypropylene film has been widely used as a packaging material for items such as food and textile products due to its excellent transparency and mechanical properties.
• biaxially oriented polypropylene film can have poor slip properties or can suffer from blocking, where films stick to each other, making it difficult to work with when processing the film, so it is known to add an anti-blocking agent.
• biaxially oriented polypropylene film When printing on biaxially oriented polypropylene film, it is necessary to improve the transferability of the printing ink from the printing roll to the film surface and the adhesion of the printing ink to the film surface from the standpoint of color development and color fading.
• polypropylene resins are non-polar, their surface energy is low, and biaxially oriented polypropylene film may not have sufficient adhesion to deposition layers, coating layers, printing inks, etc.
• Patent Document 1 discloses a film with improved adhesion to printing ink, which is made by blending an antiblocking agent into the film to create a surface layer with a specified surface roughness and wetting tension.
• Patent Document 2 discloses a film containing an antiblocking agent to form a surface layer with relatively small surface roughness and a predetermined wetting tension.
• the film described in Patent Document 1 had poor adhesion to the aluminum vapor deposition film when an aluminum vapor deposition film was provided on the surface layer.
• the film described in Patent Document 2 had poor film formability due to unstable longitudinal stretching, and the resulting film had poor appearance and unstable physical properties.
• the present invention aims to provide a biaxially oriented polypropylene film that has excellent thermal dimensional stability and mechanical strength, as well as an excellent appearance, and that is easy to work with when providing a functional layer such as a deposition layer or coating layer on the film, and has excellent adhesion to the functional layer.
• the present invention has been able to solve the above-mentioned problems by providing a biaxially oriented polypropylene film having a base layer A made of a polypropylene-based resin composition and a surface layer B made of a polypropylene-based resin composition on one side of the base layer A, and by controlling the composition of the polypropylene-based resin composition in the surface layer B and the film-forming conditions of the film. That is, the present invention has the following configuration.
• the Martens hardness of the surface layer B is 248 N/ mm2 or less.
• the surface layer B has a wetting tension of 36 mN/m or more.
• the sum of the heat shrinkage rate at 150°C in the longitudinal direction and the heat shrinkage rate at 150°C in the transverse direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less.
• the rate of fall-off of the antiblocking agent in the surface layer B is 10% or less.
• a laminate comprising a functional layer provided on the surface layer B of the biaxially oriented polypropylene film according to any one of [1] to [7] above.
• a biaxially oriented polypropylene film having excellent thermal dimensional stability and mechanical strength can be obtained.
• a functional layer such as a deposition layer or a coating layer
• a biaxially oriented polypropylene film having excellent workability and excellent adhesion to the functional layer can be stably obtained.
• a layer made of metal and/or metal oxide is provided on the biaxially oriented polypropylene film of the present invention, a laminate having high gas barrier properties can be obtained.
• the biaxially oriented polypropylene film of the present invention has a base layer A made of a polypropylene-based resin composition and a surface layer B made of a polypropylene-based resin composition. It is preferable that the biaxially oriented polypropylene film of the present invention further has a surface layer C, and specifically, it is preferable that the base layer A has a surface layer B on one side thereof and the base layer A has a surface layer C on the other side thereof.
• the biaxially oriented polypropylene film of the present invention satisfies the following (1) to (4).
• the "biaxially oriented polypropylene film of the present invention” may be simply referred to as the "film".
• the Martens hardness of the surface layer B is 248 N/ mm2 or less.
• the wetting tension of the surface layer B is 36 mN/m or more.
• the sum of the heat shrinkage rate at 150°C in the longitudinal direction and the heat shrinkage rate at 150°C in the transverse direction of the biaxially oriented polypropylene film is 0.0% or more and 25.0% or less.
• the rate of fall-off of the antiblocking agent in the surface layer B is 10% or less.
• the base layer A preferably enhances the thermal dimensional stability, mechanical strength, and transparency of the biaxially oriented polypropylene film of the present invention.
• the base layer A is made of a polypropylene resin composition mainly composed of a polypropylene homopolymer.
• the term "main component" means that 70% by mass or more of the entire base layer A is a polypropylene homopolymer, more preferably 80% by mass or more of the entire base layer A is a polypropylene homopolymer, even more preferably 90% by mass or more of the entire base layer A is a polypropylene homopolymer, and particularly preferably 95% by mass or more of the entire base layer A is a polypropylene homopolymer.
• the polypropylene homopolymer used in the base layer A is a polypropylene polymer that does not substantially contain ⁇ -olefin components other than propylene, specifically, a polypropylene (co)polymer having 1 mol% or less of ⁇ -olefin components other than propylene and 99 mol% or more of propylene as constituent units.
• the polypropylene homopolymer includes not only a polypropylene homopolymer that does not contain any ⁇ -olefin components other than propylene, but also a polypropylene copolymer having 1 mol% or less of ⁇ -olefin components other than propylene and 99 mol% or more of propylene as constituent units.
• the content of the ⁇ -olefin component other than propylene is 1 mol% or less, as described above, preferably 0.3 mol% or less, more preferably 0.2 mol% or less, and even more preferably 0.1 mol% or less.
• the crystallinity is likely to be improved.
• Examples of the ⁇ -olefin component having 4 or more carbon atoms include 1-butene, 1-pentene, 3-methyl-1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 5-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, and 1-eicosene.
• the polypropylene homopolymer two or more different polypropylene homopolymers can also be used.
• the polypropylene homopolymer used in the base layer A preferably has a melting point of 160°C or more and 175°C or less, more preferably 164°C or more and 173°C or less, and even more preferably 166°C or more and 171°C or less. If the melting point is 160°C or more, the thermal dimensional stability and mechanical strength can be increased. If the melting point is 175°C or less, it is easy to suppress the increase in cost in polypropylene production, and the film is less likely to break during film formation. The melting point can also be further increased by blending a crystal nucleating agent with the above-mentioned polypropylene resin.
• the melting point was measured by a differential scanning calorimeter (DSC) and is the main endothermic peak temperature associated with melting, which is observed when 1 to 10 mg of a sample is packed and set in an aluminum pan, melted at 230° C. for 5 minutes in a nitrogen atmosphere, cooled to 30° C. at a scanning rate of ⁇ 10° C./min, held for 5 minutes, and then heated at a scanning rate of 10° C./min.
• DSC differential scanning calorimeter
• the polypropylene homopolymer used in the base layer A preferably has a mesopentad fraction ([mmmm]%), which is an index of stereoregularity, of 95.0 to 99.9%, more preferably 97.0 to 99.7%, even more preferably 97.5 to 99.5%, and particularly preferably 98.0 to 99.3%. If it is 95.0% or more, the crystallinity of the polypropylene resin is increased, and the melting point, crystallinity, and crystal orientation of the crystals in the base layer A are improved, and the thermal dimensional stability and mechanical strength can be increased. If it is 99.9% or less, it is easier to reduce the cost of polypropylene production and the film is less likely to break during film formation.
• the mesopentad fraction is measured by the nuclear magnetic resonance method (the so-called NMR method).
• the melt flow rate (MFR) of the polypropylene homopolymer used in the base layer A is preferably 4.0 to 30 g/10 min, more preferably 4.5 to 25 g/10 min, even more preferably 4.8 to 22 g/10 min, particularly preferably 5.0 to 20 g/10 min, and most preferably 5.5 to 10 g/10 min.
• the MFR of the polypropylene resin is 4.0 g/10 min or more
• the amount of low molecular weight components in the polypropylene resin constituting the base layer A increases, which promotes oriented crystallization of the polypropylene resin, makes it easier to increase the crystallinity in the base layer A, and reduces entanglement of polypropylene molecular chains in the amorphous portion, thereby improving thermal dimensional stability and mechanical strength.
• the MFR of the polypropylene resin is 30 g/10 min or less, the film formability of the film is easily maintained.
• the polypropylene homopolymer used in the base layer A preferably has a weight average molecular weight (Mw) of 180,000 to 500,000. If the Mw is less than 180,000, the melt viscosity is low, which may cause instability during casting and poor film-forming properties. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less decreases, which may cause a decrease in the heat shrinkage rate at high temperatures.
• the Mw is more preferably 190,000 to 400,000, even more preferably 200,000 to 380,000, and particularly preferably 210,000 to 350,000.
• the number average molecular weight (Mn) of the polypropylene homopolymer used in the base layer A is preferably 20,000 to 200,000. If it is less than 20,000, the melt viscosity is low, so it may not be stable when cast and film formability may be poor. If it exceeds 200,000, the heat shrinkage rate at high temperatures may decrease. Mn is more preferably 30,000 to 120,000, even more preferably 40,000 to 110,000, particularly preferably 50,000 to 100,000, and most preferably 60,000 to 90,000.
• the polypropylene homopolymer used in the base layer A preferably has an Mw/Mn ratio, which is an index of molecular weight distribution, of 2.8 to 10. More preferably, it is 3.0 to 8.0, even more preferably 3.2 to 6.0, and particularly preferably 3.5 to 5.0.
• the Mw/Mn ratio of the polypropylene homopolymer is 2.8 or more, the proportion of low molecular weight components in the polypropylene resin constituting the base layer A increases, so that the oriented crystallization of the polypropylene resin is more promoted, the crystallization degree in the base layer A is more likely to be increased, and the entanglement of the polypropylene molecular chains in the amorphous portion is reduced, thereby improving the thermal dimensional stability and mechanical strength.
• the molecular weight distribution of the polypropylene homopolymer can be adjusted by polymerizing components of different molecular weights in a series of plants in multiple stages, blending components of different molecular weights in an offline kneader, polymerizing by blending catalysts with different performances, or using a catalyst that can achieve the desired molecular weight distribution.
• the propylene-based resin composition constituting the base layer A may contain additives or other resins other than the polypropylene homopolymer.
• additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, antifogging agents, flame retardants, inorganic or organic fillers, etc.
• other resins include polyolefin resins other than the polypropylene homopolymer used in the base layer A, various elastomers, etc.
• the surface layer B has high adhesion to a functional layer such as a vapor deposition layer or a coating layer, and further has slip properties and anti-blocking properties when the functional layer is provided on the surface layer B.
• the functional layer is a layer having at least one function such as coating properties, design properties, water vapor barrier properties, oxygen barrier properties, thermal conductivity, low dielectric properties, high dielectric properties, heat resistance, etc., and examples of the functional layer include a vapor deposition layer, a coating layer, and a printed layer.
• the surface layer B preferably contains 25% by mass or more and 85% by mass or less of a polypropylene resin having a melting point of 130° C. or more and 158° C. or less.
• the polypropylene resin composition constituting the surface layer B preferably contains 25% by mass or more and 85% by mass or less of a polypropylene resin having a melting point of 130° C. or more and 158° C. or less.
• the surface layer B preferably contains a polypropylene resin having a melting point of 159° C. or more and 175° C. or less.
• or less is small, specifically, it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, and most preferably 0% by mass (not including a polypropylene resin having a melting point of 129° C. or less).
• the polypropylene resin having a melting point of 159°C or more and 175°C or less used in the surface layer B may be referred to as a "high melting point polypropylene resin”
• the polypropylene resin having a melting point of 130°C or more and 158°C or less may be referred to as a "mid-melting point polypropylene resin”
• the polypropylene resin having a melting point of 129°C or less may be referred to as a "low melting point polypropylene resin”.
• the melting points of the polypropylene resins used in the surface layer B are rounded off to the first decimal place and classified as high melting point polypropylene resins, mid melting point polypropylene resins, or low melting point polypropylene resins. Only one type of polypropylene resin may be used for each of the high melting point polypropylene resins, mid melting point polypropylene resins, and low melting point polypropylene resins, or two or more different types of polypropylene resins may be used.
• the surface layer B contains 25% by mass or more and 85% by mass or less of the mid-melting point polypropylene resin
• the adhesion to the deposition layer, the coating layer, etc. can be further improved.
• the melting point of the mid-melting point polypropylene resin is 158°C or less
• the adhesion to the functional layer can be improved.
• the melting point is 130°C or more, the productivity during film formation can be ensured and the roughness of the film surface can be suppressed.
• the melting point of the mid-melting point polypropylene resin is preferably 134°C or more and 150°C or less, more preferably 138°C or more and 143°C or less.
• the surface layer B more preferably contains 30% by mass or more and 80% by mass or less of the mid-melting point polypropylene resin, and even more preferably contains 35% by mass or more and 75% by mass or less.
• surface layer B preferably contains a high-melting point polypropylene resin with a higher melting point than the mid-melting point polypropylene resin in order to maintain the thermal dimensional stability and mechanical strength of the biaxially oriented polypropylene film.
• the high-melting point polypropylene resin preferably has a melting point of 160°C or more and 170°C or less, and more preferably 161°C or more and 165°C or less.
• Surface layer B preferably contains 15% by mass or more and 75% by mass or less of the high-melting point polypropylene resin, more preferably 20% by mass or more and 70% by mass or less, and even more preferably 25% by mass or more and 65% by mass or less.
• the total amount of the high melting point polypropylene resin and the mid melting point polypropylene resin relative to the total resin contained in the surface layer B is preferably 60 to 100 mass%, more preferably 70 to 100 mass%, even more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, particularly preferably 95 to 100 mass%, and most preferably 98 to 100 mass%.
• mid-melting point polypropylene resin and high-melting point polypropylene resin are described.
• the mass average of the physical properties of each polypropylene resin falls within the numerical range described below.
• the mass average of the physical properties of each polypropylene resin falls within the numerical range described below.
• the melt flow rate (MFR; 230°C, 2.16 kgf) of the mid-melting point polypropylene resin is preferably 2.0 g/10 min or more and 10 g/10 min or less. More preferably, it is 3.0 g/10 min or more and 8.0 g/10 min or less, and even more preferably, it is 4.0 g/10 min or more and 7.0 g/10 min or less.
• the melt flow rate (MFR; 230°C, 2.16 kgf) of the high-melting point polypropylene resin is preferably 2.0 g/10 min or more and 10 g/10 min or less, and more preferably, it is 3.0 g/10 min or more and 6.0 g/10 min or less.
• the difference between the MFR of the mid-melting point polypropylene resin and the MFR of the high-melting point polypropylene resin is preferably 2.0 g/10 min or less, and more preferably, it is 1.5 g/10 min or less.
• the weight average molecular weight (Mw) of the mid-melting point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 190,000 to 320,000, even more preferably 200,000 to 300,000, and particularly preferably 230,000 to 260,000. If the Mw is less than 180,000, the melt viscosity is low, so there is a risk that the resin will not be stable when cast and film formability will be poor. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less will be too small, so there is a risk that the heat shrinkage rate at high temperatures will be reduced.
• the Mw of the high melting point polypropylene resin is preferably 180,000 to 500,000. It is more preferably 210,000 to 400,000, even more preferably 240,000 to 350,000, and particularly preferably 270,000 to 320,000. If the Mw is less than 180,000, the melt viscosity is low, so there is a risk that the resin will not be stable when cast and film formability will be poor. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less will be too small, so there is a risk that the heat shrinkage rate at high temperatures will be reduced. It is also preferable that the Mw of the high melting point polypropylene resin is greater than the Mw of the mid melting point polypropylene resin.
• the number average molecular weight (Mn) of the mid-melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 45,000 to 55,000. If Mn is less than 20,000, the melt viscosity is low, so there is a risk of instability during casting and poor film formability. If Mn exceeds 200,000, there is a risk of reduced heat shrinkage at high temperatures.
• the Mn of the high melting point polypropylene resin is preferably 20,000 to 200,000. It is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000. If the Mn is less than 20,000, the melt viscosity is low, so there is a risk that the resin will not be stable when cast and film formability will be poor. If the Mn is more than 200,000, there is a risk that the heat shrinkage rate at high temperatures will decrease. It is also preferable that the Mn of the high melting point polypropylene resin is greater than the Mn of the mid melting point polypropylene resin.
• the molecular weight distribution (Mw/Mn) of the mid-melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, even more preferably 3.5 to 9.0, particularly preferably 4.0 to 8.0, and most preferably 4.5 to 6.0.
• the molecular weight distribution (Mw/Mn) of the high-melting point polypropylene resin is preferably 2.8 to 10, more preferably 3.2 to 9.0, even more preferably 3.5 to 9.0, particularly preferably 3.7 to 8.0, and most preferably 4.0 to 6.0. It is also preferable that the Mw/Mn of the high-melting point polypropylene resin is larger than the Mw/Mn of the mid-melting point polypropylene resin.
• High melting point polypropylene resin, mid melting point polypropylene resin, and low melting point polypropylene resin are obtained by polymerizing the raw material propylene using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.
• a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.
• ethylene and/or an ⁇ -olefin having 4 or more carbon atoms may be copolymerized, and a polypropylene resin with low stereoregularity depending on the catalyst used may be used, but a mid melting point polypropylene resin can be obtained without copolymerizing ethylene and/or an ⁇ -olefin having 4 or more carbon atoms.
• the content of ⁇ -olefin components other than propylene in the mid melting point polypropylene resin is preferably 0 to 15 mol%, more preferably 2 to 10 mol%.
• the surface layer B contains an anti-blocking agent.
• the surface layer B may also contain other additives other than the anti-blocking agent and other resins other than the polypropylene-based resin.
• additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, anti-fogging agents, flame retardants, inorganic or organic fillers, etc.
• resins include polyolefin-based resins other than the polypropylene-based resin used in the surface layer B and various elastomers, etc.
• the total resin contained in surface layer B the total of the high melting point polypropylene resin and the mid melting point polypropylene resin is preferably 70 to 100 mass%, more preferably 80 to 100 mass%, even more preferably 90 to 100 mass%, particularly preferably 95 to 100 mass%, and most preferably 98 to 100 mass%.
• the antiblocking agent is preferably a particle having a pore volume of 0.2 mL/g to 3 mL/g, more preferably a particle having a pore volume of 0.5 mL/g to 2.5 mL/g, and even more preferably a particle having a pore volume of 1.1 mL/g to 1.8 mL/g.
• the antiblocking agent can be appropriately selected from inorganic and organic particles. Among these, it is particularly preferable to use a silicon compound. Examples of silicon compounds include silica, silicate, and compounds having a main skeleton formed by siloxane bonds. In particular, porous silica particles are preferable.
• porous silica When porous silica is used, it is preferable to use one having a pore volume of 0.8 mL/g to 2 mL/g, and more preferably one having a pore volume of 1.1 mL/g to 1.8 mL/g.
• the particle shape may be spherical or amorphous, and amorphous particles are preferred.
• the average particle size is preferably 1 ⁇ m to 5 ⁇ m, more preferably 2 ⁇ m to 4 ⁇ m. The average particle size is determined by taking a photograph using a scanning electron microscope, measuring the Feret's diameter in the horizontal direction using an image analyzer, and averaging the results.
• the content of the antiblocking agent is preferably 100 ppm or more and 10,000 ppm or less, more preferably 300 ppm or more and 6,000 ppm or less, even more preferably 800 ppm or more and 4,000 ppm or less, and particularly preferably 1,200 ppm or more and 2,700 ppm or less, based on the total mass of the surface layer B.
• the three-dimensional average roughness and Martens hardness of the surface layer B can be set within a predetermined range described below.
• the slipperiness and blocking resistance of the film are excellent, and when it is 10,000 ppm or less, the excessive addition of the antiblocking agent is unlikely to cause a decrease in light transmittance, the antiblocking agent is unlikely to penetrate the functional layer when laminating the functional layer, or the functional layer formed near the surface layer B is unlikely to become sparse due to the antiblocking agent protruding from the surface layer B, and the barrier property is unlikely to decrease or the adhesion is unlikely to be poor.
• the dropout rate of the antiblocking agent in the surface layer B is 10% or less, preferably 8% or less, more preferably 6% or less, and even more preferably 4% or less.
• a dropout rate of 10% or less can suppress contamination of guide rolls in post-processing such as coating and vapor deposition.
• the generation of voids due to the dropout of the antiblocking agent can be suppressed, and a laminate with excellent gas barrier properties can be obtained when metal and/or metal oxide is vapor-deposited.
• the lower limit of the dropout rate is not particularly limited, but is, for example, 0.3% or more.
• the surface layer C is an optional layer, and is a layer mainly for expressing slipperiness and antiblocking properties.
• the melting point of the polypropylene-based resin used in the surface layer C is preferably 150° C. or higher in order to maintain thermal dimensional stability, mechanical strength, and productivity.
• a polypropylene-based resin having a melting point of 175° C. or lower is economically easy to obtain, and can suppress the antiblocking agent from falling off from the surface layer C.
• the surface layer C is preferably made of a polypropylene resin composition containing a polypropylene resin having a melting point of 150°C to 175°C and an antiblocking agent. Only one type of polypropylene resin may be used as the polypropylene resin having a melting point of 150°C to 175°C, or two or more different types of polypropylene resins may be used.
• the total content of the polypropylene resin having a melting point of 150°C to 175°C and the antiblocking agent is preferably 90 to 100 mass%, more preferably 95 to 100 mass%, and even more preferably 98 to 100 mass%.
• the melting point of the polypropylene resin used in the surface layer C is preferably 154 to 170°C, and more preferably 158 to 165°C.
• the polypropylene resin with a melting point of 150°C or higher and 175°C or lower is preferably a polypropylene homopolymer (a polypropylene homopolymer that does not contain any ⁇ -olefin components other than propylene and/or a polypropylene copolymer whose constituent units are 1 mol% or less of ⁇ -olefin components other than propylene and 99 mol% or more of propylene).
• the weight average molecular weight (Mw) of the polypropylene resin with a melting point of 150°C or higher and 175°C or lower used in the surface layer C is preferably 180,000 to 500,000. If the Mw is less than 180,000, the melt viscosity is low, so the resin is not stable when cast, and film-forming properties may be poor. If the Mw exceeds 500,000, the amount of components with a molecular weight of 100,000 or less decreases, and there is a risk of a reduction in the heat shrinkage rate at high temperatures.
• the Mw is more preferably 190,000 to 400,000, even more preferably 230,000 to 380,000, and particularly preferably 270,000 to 350,000.
• the polypropylene resin used in the surface layer C which has a melting point of 150°C or higher and 175°C or lower, preferably has a number average molecular weight (Mn) of 20,000 to 200,000. If Mn is less than 20,000, the melt viscosity is low, making the resin unstable when cast and resulting in poor film formability. If Mn exceeds 200,000, there is a risk of reduced heat shrinkage at high temperatures. Mn is more preferably 30,000 to 80,000, even more preferably 40,000 to 70,000, and particularly preferably 50,000 to 60,000.
• the polypropylene resin used in the surface layer C which has a melting point of 150°C or more and 175°C or less, preferably has an Mw/Mn ratio, which is an index of molecular weight distribution, of 2.8 or more and 10 or less. More preferably, it is 3.2 or more and 8.0 or less, even more preferably, it is 3.5 or more and 7.0 or less, and particularly preferably, it is 4.0 or more and 6.0 or less.
• the surface layer C may contain additives or other resins other than polypropylene resins having a melting point of 150°C or more and 175°C or less.
• additives include antiblocking agents, antioxidants, UV absorbers, nucleating agents, adhesives, antifogging agents, flame retardants, inorganic or organic fillers, etc., and from the viewpoint of imparting slipperiness and antiblocking properties to the surface layer C, it is preferable that the surface layer C contains an antiblocking agent.
• other resins include polyolefin resins other than polypropylene resins having a melting point of 150°C or more and 175°C or less, and various elastomers.
• the polypropylene resin with a melting point of 150°C or higher and 175°C or lower preferably accounts for 80 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and particularly preferably 98 to 100% by mass.
• the antiblocking agent is preferably a particle having a pore volume of 0.2 mL/g to 3 mL/g, more preferably a particle having a pore volume of 0.5 mL/g to 2.5 mL/g, and even more preferably a particle having a pore volume of 1.1 mL/g to 1.8 mL/g.
• the antiblocking agent can be appropriately selected from inorganic and organic particles. Among these, it is particularly preferable to use a silicon compound. Examples of silicon compounds include silica, silicate, and compounds having a main skeleton formed by siloxane bonds. In particular, porous silica particles are preferable.
• porous silica When porous silica is used, it is preferable to use a porous silica having a pore volume of 0.8 mL/g to 2 mL/g, and more preferably a porous silica having a pore volume of 1.1 mL/g to 1.8 mL/g. It is preferable to use the same antiblocking agent contained in the surface layer C as the antiblocking agent contained in the surface layer B.
• the particle shape may be spherical or amorphous, and amorphous particles are preferred.
• the average particle size is preferably 1 ⁇ m to 5 ⁇ m, more preferably 2 ⁇ m to 4 ⁇ m.
• the average particle size is determined by taking a photograph using a scanning electron microscope, measuring the Feret's diameter in the horizontal direction using an image analyzer, and averaging the results.
• the content of the antiblocking agent is preferably 100 ppm or more and 10,000 ppm or less in the total mass of the surface layer C, more preferably 300 ppm or more and 6,000 ppm or less, even more preferably 800 ppm or more and 4,000 ppm or less, and particularly preferably 1,500 ppm or more and 3,000 ppm or less.
• the slipperiness and blocking resistance of the film are excellent, and when it is 10,000 ppm or less, the excessive addition of the antiblocking agent causes a decrease in permeability, the antiblocking agent penetrates the functional layer when laminating the functional layer, and the functional layer formed near the surface layer B is unlikely to become sparse due to the antiblocking agent protruding from the surface layer C, and the barrier property is unlikely to decrease and the adhesion is unlikely to be poor.
• the content of the antiblocking agent in the surface layer C is preferably greater than the content of the antiblocking agent in the surface layer B.
• the dropout rate of the antiblocking agent in the surface layer C is preferably 10% or less, more preferably 8% or less, even more preferably 6% or less, and particularly preferably 4% or less. If the dropout rate is 10% or less, contamination of the guide roll during post-processing such as coating and vapor deposition can be suppressed. In addition, the generation of voids due to the dropout of the antiblocking agent can be suppressed, and when metal and/or metal oxide is vapor-deposited, a product with excellent gas barrier properties can be obtained. There is no particular limit to the lower limit of the dropout rate, but it is, for example, 0.3% or more.
• the biaxially oriented polypropylene film of the present invention has a surface layer B on one side of the base layer A, and the surface layer B may be directly laminated on the surface of the base layer A, or another layer may be interposed between the base layer A and the surface layer B.
• the surface layer C when the surface layer C is on the other side of the base layer A, the surface layer C may be directly laminated on the surface of the base layer A, or another layer may be interposed between the base layer A and the surface layer C.
• the biaxially oriented polypropylene film of the present invention may have a two-layer structure of only the surface layer B/base layer A, a three-layer structure of only the surface layer B/base layer A/surface layer C, or a multi-layer structure of four or more layers including layers other than the base layer A, the surface layer B, and the surface layer C.
• the four-layer structure include the surface layer B/intermediate layer D/base layer A/surface layer C, and by providing the intermediate layer D, the adhesion between the base layer A and the surface layer B can be further increased.
• the overall thickness of the biaxially oriented polypropylene film of the present invention is preferably 5 to 100 ⁇ m, more preferably 10 to 80 ⁇ m, and even more preferably 18 to 50 ⁇ m. If it is within the above range, the film has sufficient rigidity and is suitable as a base material for packaging and industrial use.
• the thickness of surface layer B is preferably 0.3 ⁇ m to 10 ⁇ m, more preferably 0.5 ⁇ m to 3 ⁇ m, and even more preferably 0.8 ⁇ m to 2 ⁇ m.
• a thickness of 0.3 ⁇ m or more can increase the adhesion between surface layer B and the functional layer, making it suitable as a substrate for packaging or industrial use that requires the addition of a functional layer by deposition processing, coating processing, or the like. If the thickness of surface layer B is thicker than 10 ⁇ m, there is a risk that the thickness ratio of substrate layer A will become relatively low, which may result in a decrease in the rigidity and thermal dimensional stability of the film.
• the thickness of the surface layer C is preferably 0.3 ⁇ m to 10 ⁇ m, more preferably 0.5 ⁇ m to 5 ⁇ m, and even more preferably 0.8 ⁇ m to 3 ⁇ m.
• a thickness of 0.3 ⁇ m or more makes it easier to ensure the slipperiness and processability of the film. If the thickness of the surface layer C is thicker than 10 ⁇ m, there is a risk that the thickness ratio of the base layer A will become relatively low, which may result in a decrease in the rigidity and thermal dimensional stability of the film.
• the thickness of the base layer A is preferably 5 to 90 ⁇ m, more preferably 10 to 50 ⁇ m, and even more preferably 15 to 30 ⁇ m. A thickness of 5 ⁇ m or more can improve the thermal dimensional stability and mechanical strength of the film. If the thickness of the base layer A is thicker than 90 ⁇ m, the thermal dimensional stability and mechanical strength can be improved, but there is a risk that the effect will become saturated.
• the biaxially oriented polypropylene film of the present invention can be obtained by melt-extruding the polypropylene resin compositions constituting each layer, such as the base layer A and the surface layer B, using separate extruders, co-extruding them through a die, and cooling them with a cooling roll to form an unstretched sheet, stretching the unstretched sheet in the machine direction (MD) and transverse direction (TD), and then subjecting it to a heat setting treatment.
• MD machine direction
• TD transverse direction
• the melt extrusion temperature is preferably about 200 to 280°C.
• MFR difference the difference between the MFR of base layer A and the MFR of surface layer B. If the MFR difference is more than 5.0 g/10 min, the layers are likely to be disturbed and the appearance is likely to be poor. It is more preferable that it is 4.0 g/10 min or less, and even more preferable that it is 3.0 g/10 min or less.
• the difference between the maximum MFR and the minimum MFR of the three polypropylene resin compositions constituting base layer A, surface layer B, and surface layer C is 5.0 g/10 min or less, and more preferably 3.0 g/10 min or less.
• the surface temperature of the cooling roll is preferably 25 to 50°C, and more preferably 30 to 45°C. If the cooling roll temperature is 50°C or less, crystallization of the unstretched sheet and growth of spherulites can be suppressed, allowing for a high stretch ratio and a film with a high tensile modulus to be obtained. In addition, the occurrence of large surface irregularities resulting from spherulites can be suppressed, allowing a film with appropriate surface roughness to be obtained.
• the lower limit of the stretch ratio in the longitudinal direction (MD) is preferably 3.5 times or more, and more preferably 4 times or more. If it is 3.5 times or more, thickness unevenness can be reduced.
• the upper limit of the stretch ratio in the MD is preferably 8 times or less, and more preferably 7 times or less. If it is 8 times or less, breakage is unlikely to occur in the subsequent TD stretching, making production easier.
• the lower limit of the MD stretching temperature is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 135°C or higher. At 120°C or higher, thickness unevenness is less likely to become large and the film surface is less likely to become rough. A higher MD stretching temperature makes it less likely that voids will form around the antiblocking agent particles, preventing roll contamination during processing due to the antiblocking agent particles falling off the film surface. In addition, good gas barrier properties are obtained when aluminum is vapor-deposited.
• the upper limit of the MD stretching temperature is preferably 150°C or less, more preferably 145°C or less, and even more preferably 140°C or less. If the MD stretching temperature is too high, the film may begin to stick to the MD stretching rolls, causing stick-slip and causing spots on the film and a rough surface. If the MD stretching temperature is made even higher, the film may stick to the stretching rolls, making it impossible to stretch.
• the lower limit of the stretch ratio in the transverse direction (TD) is preferably 6 times or more, more preferably 7 times or more, and even more preferably 8 times or more. If it is 6 times or more, thickness unevenness is unlikely to become large.
• the upper limit of the TD stretch ratio is preferably 15 times or less, more preferably 13 times or less, and even more preferably 11 times or less. If it exceeds the above, the thermal shrinkage rate may become high and there is a risk of frequent breakage during stretching.
• the preheating temperature in TD stretching is preferably set 1 to 5°C higher than the stretching temperature. If the mesopentad fraction of the polypropylene homopolymer constituting the base layer A is high, the preheating temperature in TD stretching is preferably set 7 to 20°C higher than the stretching temperature in order to quickly raise the preheating temperature in TD stretching to near the stretching temperature.
• the lower limit of the TD stretching temperature is preferably 150°C or higher, more preferably 152°C or higher, even more preferably 154°C or higher, and particularly preferably 156°C or higher.
• the upper limit of the TD stretching temperature is preferably 170°C or lower, more preferably 168°C or lower, and even more preferably 166°C or lower.
• a high heat setting temperature is preferable, more preferably 160°C or higher, and even more preferably 162°C or higher. If the temperature is 160°C or higher, the heat shrinkage rate is unlikely to become high, and long-term treatment is not necessary to reduce the heat shrinkage rate.
• the upper limit of the heat setting temperature is preferably 180°C or lower, and more preferably 175°C or lower. If the temperature is 180°C or lower, melting of low-molecular-weight components and loss of orientation due to recrystallization are unlikely to occur, and surface roughness and whitening of the film are unlikely to occur.
• the lower limit of the relaxation rate is preferably 2% or more, more preferably 3% or more, and even more preferably 5% or more. If it is 2% or more, the thermal shrinkage rate is unlikely to become high.
• the upper limit of the relaxation rate is preferably 10% or less, and more preferably 8% or less. If it is 10% or less, thickness unevenness is unlikely to become large.
• the film produced by the above process can be wound into a roll and then annealed offline.
• the film thus obtained can be subjected to corona discharge, plasma treatment, flame treatment, etc., as necessary, and then wound up with a winder to obtain the biaxially oriented polypropylene film roll of the present invention.
• the method for producing the biaxially oriented polypropylene film of the present invention is not limited to the above-mentioned method.
• the haze of the biaxially oriented polypropylene film of the present invention is preferably 8% or less, more preferably 5% or less, even more preferably 4% or less, and particularly preferably 3% or less.
• the haze tends to deteriorate when the stretching temperature or heat setting temperature is too high, when the cooling roll temperature is high and the cooling rate of the unstretched (raw) sheet is slow, or when there is too much low molecular weight component with a molecular weight of 100,000 or less, and the haze can be adjusted to within the above range by adjusting these conditions.
• the tensile modulus in the longitudinal direction of the biaxially oriented polypropylene film of the present invention is preferably 1.0 GPa or more, more preferably 1.5 GPa or more, even more preferably 1.8 GPa or more, and particularly preferably 2.0 GPa or more.
• the tensile modulus in the width direction of the biaxially oriented polypropylene film of the present invention is preferably 3.0 GPa or more, more preferably 3.2 GPa or more, and even more preferably 3.5 GPa or more.
• the upper limit is not particularly limited, and is, for example, 10 GPa or less.
• the sum of the tensile modulus in the longitudinal and transverse directions of the biaxially oriented polypropylene film of the present invention is preferably 5.8 to 12.0 Pa, more preferably 6.0 to 10.0 GPa. If the tensile modulus is within the above range, the film will be strong and can be used even if it is thin, which in turn makes it possible to reduce costs.
• the "longitudinal direction" of the biaxially oriented polypropylene film of the present invention is the direction corresponding to the flow direction in the film production process, and the "width direction” is the direction perpendicular to the flow direction in the film production process, and the same applies below.
• the thermal shrinkage rate in the longitudinal direction of the biaxially oriented polypropylene film of the present invention at 150°C is preferably 15.0% or less, more preferably 9.0% or less, even more preferably 7.0% or less, and particularly preferably 5.0% or less.
• the lower limit of the thermal shrinkage rate in the longitudinal direction at 150°C is preferably 0% or more. If it is within the above range, it can be used in applications where it may be exposed to high temperatures. In addition, even when a functional layer is laminated on the film, the deterioration of the barrier property of the functional layer can be suppressed, and as a result, the barrier property of the laminate can be enhanced.
• the heat shrinkage rate in the width direction of the biaxially oriented polypropylene film of the present invention at 150°C is preferably 20.0% or less, more preferably 10.0% or less, and even more preferably 8.0% or less.
• the lower limit of the heat shrinkage rate in the width direction at 150°C is preferably 0% or more. If it is within the above range, it can be used in applications where it may be exposed to high temperatures. In addition, even if a functional layer is laminated on the film, the deterioration of the barrier property of the functional layer can be suppressed, and as a result, the barrier property of the laminate can be enhanced.
• the sum of the thermal shrinkage rates in the longitudinal and transverse directions of the biaxially oriented polypropylene film of the present invention at 150°C is 25.0% or less, preferably 23.0% or less, more preferably 20.0% or less, even more preferably 15.0% or less, and particularly preferably 12.0% or less.
• the lower limit of the sum of the thermal shrinkage rates in the longitudinal and transverse directions at 150°C is 0% or more. Within the above range, it can be used in applications where it may be exposed to high temperatures. In addition, even when a functional layer is laminated on the film, the deterioration of the barrier property of the functional layer can be suppressed, and as a result, the barrier property of the laminate can be enhanced.
• the surface wet tension of the surface layer B of the biaxially oriented polypropylene film of the present invention is 36 mN/m or more, preferably 38 mN/m or more, more preferably 40 mN/m or more. If the wet tension is 36 mN/m or more, the adhesion with the functional layer is improved. In order to make the wet tension 36 mN/m or more, it is preferable to perform a physicochemical surface treatment such as a corona treatment or a flame treatment. In the corona treatment, it is preferable to use a preheat roll and a treatment roll and perform discharge in the air. If the wet tension is too high, the slipperiness and antiblocking properties may deteriorate, so it is preferable that the wet tension is 46 mN/m or less.
• the surface wet tension is preferably 36 mN/m or more, more preferably 38 mN/m or more, and even more preferably 40 mN/m or more, similar to the surface layer B. If the wet tension is too high, slipperiness and anti-blocking properties may deteriorate, so it is preferably 46 mN/m or less. When no other materials are laminated on the surface of the surface layer C, a wet tension of 32 mN/m or less is preferable in terms of slipperiness and anti-blocking properties.
• the surface resistance value of the surface layer B of the biaxially oriented polypropylene film of the present invention is preferably 14 Log ⁇ or more, more preferably 14.5 Log ⁇ or more, and even more preferably 15 Log ⁇ or more. If the film contains additives such as antistatic agents or impurities, the surface resistance value will be less than 14 Log ⁇ , which may result in poor adhesion. A surface resistance value of 14 Log ⁇ or more is preferable in terms of adhesion to the functional layer.
• the preferred upper limit of the surface resistance value of the surface layer B is not particularly limited, but is 18 Log ⁇ or less in terms of production.
• the surface resistance value of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 14 Log ⁇ or more, more preferably 14.5 Log ⁇ or more, and even more preferably 15 Log ⁇ or more. If the film contains additives such as antistatic agents or impurities, the surface resistance value will be less than 14 Log ⁇ , which may result in poor adhesion. A surface resistance value of 14 Log ⁇ or more is preferable in terms of adhesion to the functional layer.
• the preferred upper limit of the surface resistance value of the surface layer C is not particularly limited, but is 18 Log ⁇ or less for manufacturing reasons.
• the Martens hardness of the surface layer B of the biaxially oriented polypropylene film of the present invention is 248 N/ mm2 or less, preferably 245 N/ mm2 or less, more preferably 230 N/ mm2 or less, and even more preferably 210 N/mm2 or less.
• the Martens hardness of the surface layer B being 248 N/mm 2 or less, the adhesion between the surface layer B and the functional layer is improved. Furthermore, even if the ratio of the thickness of the surface layer B to the thickness of the entire film is reduced, the adhesion is easily improved.
• the Martens hardness is easily made 248 N/mm 2 or less.
• the lower limit of the Martens hardness of the surface layer B is preferably 150 N/mm 2 or more, more preferably 165 N/mm 2 or more.
• the Martens hardness of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 250 N/ mm2 or more, more preferably 260 N/ mm2 or more, and even more preferably 270 N/ mm2 or more.
• the upper limit of the Martens hardness of the surface layer C is preferably 350 N/ mm2 or less, and more preferably 300 N/ mm2 or less.
• the Martens hardness of the surface layer B indicates the hardness of the surface layer B measured using a dynamic ultra-microhardness tester under the conditions described in the Examples described later.
• the Martens hardness of the surface layer C is also measured in the same manner.
• the three-dimensional average roughness SRa of the surface layer B of the biaxially oriented polypropylene film of the present invention is preferably 10 nm or more and 100 nm or less, more preferably 13 nm or more and 90 nm or less, even more preferably 15 nm or more and 80 nm or less, particularly preferably 17 nm or more and 70 nm or less, and most preferably 19 nm or more and 50 nm or less.
• the three-dimensional average roughness of the surface layer B is 10 nm or more, the film has good slipperiness, and wrinkles can be suppressed when wound into a roll or during post-processing such as deposition processing.
• the film when the three-dimensional average roughness is 100 nm or less, the film has good transparency, and the film can be prevented from slipping too much when wound into a roll or during post-processing such as deposition processing, which can prevent workability from deteriorating.
• the three-dimensional average roughness SRa of the surface layer C of the biaxially oriented polypropylene film of the present invention is preferably 15 nm or more and 100 nm or less, more preferably 20 nm or more and 70 nm or less, and even more preferably 30 nm or more and 50 nm or less.
• the film has good slipperiness, and the occurrence of wrinkles can be suppressed when wound into a roll or during post-processing such as vapor deposition.
• the film has good transparency, and the film is prevented from slipping too much when wound into a roll or during post-processing such as vapor deposition, which would cause deterioration of workability.
• Laminate further provided with a functional layer
• the biaxially oriented polypropylene film of the present invention is not limited to packaging use, and can be used for industrial purposes.
• a laminate can be provided with a functional layer such as a deposition layer, a coating layer, or a printing layer.
• the material of the deposition layer is preferably a metal and/or a metal oxide, more preferably aluminum, Al 2 O 3 , SiO x (x ⁇ 2), a mixture of Al 2 O 3 and SiO 2 , or a mixture of Al and SiO 2 , and even more preferably a mixture of aluminum or Al and SiO 2.
• the thickness of the deposition layer is preferably 5 to 40 nm, more preferably 10 to 30 nm.
• the deposition layer may be prepared by any known method, such as PVD (physical vapor deposition) methods such as vacuum deposition, sputtering, and ion plating, or CVD (chemical vapor deposition), but the physical vapor deposition method is preferred, and the vacuum vapor deposition method is more preferred.
• PVD physical vapor deposition
• CVD chemical vapor deposition
• the deposition material aluminum, Al 2 O 3 , SiO x (x ⁇ 2), a mixture of Al 2 O 3 and SiO 2 , or a mixture of Al and SiO 2 may be used as the deposition material, and known methods such as resistance heating, high-frequency induction heating, and electron beam heating may be used as the heating method.
• oxygen, nitrogen, water vapor, etc. may be introduced as the reactive gas, and reactive vapor deposition using means such as ozone addition and ion assist may be used.
• preparation conditions may be changed as long as the object of the present invention is not impaired, such as applying a bias to the biaxially oriented polypropylene film of the present invention or raising and lowering the temperature of the biaxially oriented polypropylene film of the present invention.
• a bias to the biaxially oriented polypropylene film of the present invention or raising and lowering the temperature of the biaxially oriented polypropylene film of the present invention.
• other preparation methods such as sputtering and CVD.
• the coating amount after drying is preferably 0.03 to 3 g/ m2 , and more preferably 0.1 to 0.3 g/ m2 .
• the upper limit of oxygen permeability of the vapor deposition film provided with the vapor deposition layer at a temperature of 23° C. and a relative humidity of 65% is preferably 50 mL/m 2 /day/MPa, more preferably 39 mL/m 2 /day/MPa, even more preferably 30 mL/m 2 /day/MPa, and particularly preferably 25 mL/m 2 /day/MPa.
• the upper limit of oxygen permeability of the vapor deposition film at a temperature of 23° C. and a relative humidity of 65% is not particularly limited, but is preferably 0.1 mL/m 2 /day/MPa from the viewpoint of productivity.
• Heat-sealable laminate When the biaxially oriented polypropylene film of the present invention or a laminate having a vapor deposition layer and/or a coating layer thereon is used for packaging, it can be processed into a packaging bag as a heat-sealable laminate laminated with a heat-sealable film.
• the heat-sealable film include unstretched films, uniaxially stretched films, and biaxially stretched films made of low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, and polyester.
• unstretched films or uniaxially stretched films made of low-density polyethylene, linear low-density polyethylene, or polypropylene are preferred.
• the surface to be laminated with the heat sealable film may be either the surface layer B side or the opposite surface layer B side. It is preferable to laminate the heat sealable film via an adhesive layer.
• an adhesive an ester adhesive, a urethane adhesive, an acrylic adhesive, a polyethyleneimine adhesive, or the like can be used.
• lamination method a dry lamination method, an extrusion lamination method, a co-extrusion method, or the like can be used.
• a packaging bag processed by laminating a heat-sealable film onto the biaxially oriented polypropylene film of the present invention or a laminate having a vapor deposition layer and/or a coating layer thereon can be used as a packaging container with excellent suitability for filling and packaging and preserving various items such as food and beverages, medicines, detergents, shampoos, oils, toothpaste, adhesives, and pressure sensitive adhesives.
• Examples of layer configurations of the heat-sealable laminate of the present invention, where the boundary of the layer configuration is represented by /, include OPP/bond/LLDPE, OPP/bond/CPP, OPP/bond/Al/bond/CPP, OPP/bond/Al/bond/LLDPE, OPP/PE/Al/bond/LLDPE, OPP/bond/Al/PE/LLDPE, PET/bond/OPP/bond/LLDPE, PET/bond/OPP/bond/Al/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OPP/bond/LLDPE, PET/bond/Al/bond/OP
• aluminum vapor deposition means that aluminum is vapor-deposited on a film
• inorganic oxide vapor deposition means that an inorganic oxide is vapor-deposited on a film
• aluminum or inorganic oxide vapor deposition means that aluminum or an inorganic oxide is vapor-deposited on a film.
• OPP biaxially oriented polypropylene film of the present invention
• PET oriented polyethylene terephthalate film
• LLDPE unoriented linear low density polyethylene film
• PE polyethylene film other than LLDPE
• CPP unoriented polypropylene film
• General OPP conventionally available commercially available oriented polypropylene film
• Al aluminum foil
• EVOH ethylene-vinyl alcohol copolymer resin film
• Adhesive adhesive layer for bonding films together
• the number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw/Mn) are each defined by the number of molecules (N i ) of the molecular weight (M i ) at each elution position of the GPC curve obtained via the molecular weight calibration curve, as shown in the following equations.
• Thickness A cross section of a film solidified with a modified urethane resin was cut out with a microtome and observed under a differential interference microscope to measure the thickness of each layer.
• Tensile modulus A sample of 10 mm in width and 180 mm in length was cut out from the film using a razor. It was measured according to JIS K 7127, and after leaving it for 12 hours under an atmosphere of 23°C and 65% relative humidity, it was measured under the conditions of 23°C, 65% relative humidity, chuck distance 100 mm, and pulling speed 200 mm/min. The average value of five measurement results was calculated and used as the tensile modulus in the length direction. The measuring device used was Shimadzu Corporation's Autograph AG5000A. Further, a sample having a width of 180 mm and a length of 10 mm was cut out from the film using a razor, and the tensile modulus in the width direction was determined by the same method as for the lengthwise tensile modulus.
• Heat shrinkage rate Measured by the following method in accordance with JIS Z 1712. The film was cut into pieces of 20 mm width and 200 mm length in both the longitudinal and transverse directions, and was hung in a hot air oven at 150° C. for 5 minutes. The length after heating was measured, and the ratio of the shrunken length to the original length was taken as the heat shrinkage rate.
• the obtained film was cut into a square of about 2 cm to prepare a sample, and the surface opposite to the measurement surface was fixed with an adhesive on a glass plate with a thickness of about 1 mm, and then the sample was left for 12 hours in an atmosphere of 23°C and relative humidity of 50% to condition the humidity.
• the Martens hardness of the surface layer B and the surface layer C of the above sample was measured under the following measurement conditions using a dynamic ultra-microhardness tester (DUH-211 manufactured by Shimadzu Corporation) according to a method in accordance with ISO14577-1 (2002). The measurement was performed 10 times by changing the position of the film, and the average value of 8 points excluding the maximum and minimum was calculated.
• Measurement environment Temperature 23°C, relative humidity 50%
• Test mode Load-unload test
• Indenter used triangular pyramid indenter with 115 degree edge angle
• Indenter elastic modulus 1.140 ⁇ 106 N/ mm2
• Indenter Poisson's ratio 0.07 Cf-Ap
• Test force 0.10 mN
• Load speed 0.0050mN/sec
• Load holding time 5 seconds
• Three-dimensional average roughness SRa The average roughness SRa of the surface layers B and C was measured by a stylus method under the following conditions using a contact type three-dimensional surface roughness meter (manufactured by Kosaka Laboratory: Model ET-4000A).
• Stylus tip radius 0.5 ⁇ m
• Stylus pressure 50 ⁇ N
• Cut-off value 800 ⁇ m
• Measurement length 500 ⁇ m
• Measurement speed 0.1 ⁇ m/sec Measurement interval: 5 ⁇ m
• Dynamic friction coefficient Two films were prepared, and the surface layer B of one film was superimposed on the surface layer C of the other film.
• the dynamic friction coefficient was measured in an atmosphere of 23°C and relative humidity of 50% using a universal tensile tester STM-T-50BP (manufactured by Toyo Baldwin Co., Ltd.) in accordance with JIS K 7125 (1999).
• a visual evaluation of A or higher on the surface layer B was considered to be acceptable, but when a functional layer is also provided on the surface layer C, it is preferable that the visual evaluations of both the surface layers B and C are A or higher.
• A+ There was no repelling of the coating layer.
• C Cracks in the coating layer were observed over the entire surface.
• Adhesion of aluminum vapor-deposited film A film was unwound from the film roll obtained by the production method described in 17) above, and deposition was performed on the surface layer B of the unwound film using a small vacuum deposition apparatus (VWR-400/ERH manufactured by ULVAC Machinery Co., Ltd.) to a film thickness of 30 nm, thereby obtaining a vapor-deposited film having an aluminum vapor-deposited film on the surface layer B.
• VWR-400/ERH manufactured by ULVAC Machinery Co., Ltd.
• Oxygen permeability of aluminum vapor-deposited film The oxygen permeability of the vapor-deposited film produced by the manufacturing method described in 19) above was measured in an atmosphere at a temperature of 23° C. and a relative humidity of 65% using an oxygen permeability measuring device (OX-TRAN 2/20 manufactured by MOCON Corp.) in accordance with the electrolytic sensor method (Appendix A) of JIS K 7126-2. The oxygen permeability was measured in the direction in which oxygen permeates from the substrate layer A side to the aluminum vapor-deposited layer.
• Laminate Strength The laminate strength was measured by the following procedure.
• Procedure 1) Preparation of a laminate of a biaxially oriented polypropylene film and a non-oriented polyethylene film The preparation was carried out using a continuous dry laminator as follows. The adhesive was gravure coated on the surface of the surface layer B of the biaxially oriented polypropylene film obtained in the examples and comparative examples so that the coating amount when dried was 2.8 g/ m2 , and then introduced into a drying zone and dried at 80°C for 5 seconds. Subsequently, the film was laminated with a sealant film between rolls provided downstream (roll pressure 0.2 MPa, roll temperature: 50°C). The obtained laminate film was aged at 40°C for 3 days in a wound state.
• the adhesive used was a urethane adhesive obtained by mixing 28.9% by mass of a base agent (TM569, manufactured by Toyo Morton Co., Ltd.), 4.00% by mass of a hardener (CAT10L, manufactured by Toyo Morton Co., Ltd.), and 67.1% by mass of ethyl acetate, and the sealant film used was a non-oriented polyethylene film manufactured by Toyobo Co., Ltd. (Rix (registered trademark) L4102, thickness 40 ⁇ m).
• Step 2) Measurement of Laminate Strength The laminate film obtained above was cut into a rectangular shape of 200 mm in length and 15 mm in width, with the longitudinal direction of the biaxially oriented polypropylene film as the long side, and the peel strength was measured when T-peeling at a pulling speed of 200 mm/min under an environment of 23°C and relative humidity of 65% using a tensile tester (Tensilon, manufactured by Orientec Co., Ltd.). The measurement was performed three times, and the average value was taken as the laminate strength.
• a tensile tester Teensilon, manufactured by Orientec Co., Ltd.
• the types of antiblocking agents used in the examples and comparative examples are shown in Table 1. In all of the examples and comparative examples, the content of the antiblocking agent in MB-1 was 5.0 mass%.
• Example 1 The base layer A was made of 70% by mass of PP-1 and 30% by mass of PP-2.
• the surface layer B was made of 26% by mass of PP-3, 20% by mass of PP-4, 50% by mass of PP-5, and 4% by mass of MB-1.
• the surface layer C was made of 25% by mass of PP-3, 70% by mass of PP-4, and 5% by mass of MB-1.
• the base layer A was made using a 45 mm extruder, the surface layer B was made using a 25 mm extruder, and the surface layer C was made using a 20 mm extruder. The raw material resins were melted at 250 ° C.
• the surface of the surface layer B of the laminate was subjected to a corona treatment using a corona treatment machine manufactured by Softal Corona & Plasma GmbH under the condition of an applied current value of 0.75 A, and then wound up with a winder to obtain a biaxially oriented polypropylene film.
• the total thickness of the obtained biaxially oriented polypropylene film was 20 ⁇ m (thicknesses of surface layer B/base layer A/surface layer C were 1.3 ⁇ m/17.7 ⁇ m/1.0 ⁇ m).
• Example 2 Comparative Examples 1 to 2, and Comparative Examples 5 to 6
• a biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the raw material composition of the surface layer B was changed as shown in Table 2.
• the raw material composition of the surface layer C was also changed as shown in Table 2.
• Example 5 A biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the surface layer C was also subjected to a corona treatment.
• Comparative Example 4 The raw material composition was the same as in Comparative Example 3, and the production conditions were the same as in Example 1 except that the longitudinal stretching temperature was lowered by 10°C to 125°C and the production conditions were changed as shown in Table 2, to obtain a biaxially oriented polypropylene film.
• Example 9 A biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the antiblocking agent contained in surface layer B and surface layer C was changed from the silica particles to the silicone particles.
• Example 10 A biaxially oriented polypropylene film was obtained under the same conditions as in Example 1, except that the antiblocking agent contained in the surface layer B and the surface layer C was changed from the silica particles to the crosslinked polymethyl methacrylate particles.
• Table 2 shows the raw material composition of each layer of the films in the examples and comparative examples, the thickness of each layer, and the film manufacturing conditions, and Table 3 shows various physical properties and various evaluations of the films in the examples and comparative examples.
• the biaxially oriented polypropylene films obtained in Examples 1 to 5 had little dirt on the guide roll during post-processing, few wrinkles in the obtained film rolls, and films cut from the film rolls had little repelling of the coating liquid on Layer B.
• the aluminum vapor-deposited layer had excellent adhesion, and the aluminum vapor-deposited film had low oxygen permeability and excellent gas barrier properties.
• the laminate strength with the non-oriented polyethylene film was high.
• the film of Comparative Example 1 had low laminate strength because the amount of polypropylene resin having a melting point of 130° C. or more and 158° C. or less was small in the surface layer B.
• the film of Comparative Example 2 had a large amount of polypropylene resin with a melting point of 130°C or more and 158°C or less in the surface layer B, so that the longitudinal stretching was unstable and the film formability was poor.
• the appearance of the biaxially oriented polypropylene film was poor due to the occurrence of stretching unevenness in the longitudinal stretching roll.
• the raw material of the base layer A was a polypropylene-based resin with a melting point of 159° C., and therefore the sum of the heat shrinkage rates at 150° C. was high. Furthermore, because the heat shrinkage rate at 150° C. was high, when an aluminum vapor-deposited film was provided on the surface layer B, the barrier property of the aluminum vapor-deposited film was reduced, and as a result, the gas barrier property of the aluminum vapor-deposited film was significantly inferior.
• the surface layer B was not subjected to corona treatment, and therefore the laminate strength was low. In addition, repelling occurred when a coating layer was provided on the surface layer B.
• the adhesion of the aluminum vapor-deposited film was poor, and the oxygen permeability of the aluminum vapor-deposited film was very high, resulting in significantly poor gas barrier properties.
• the antiblocking agent contained in the surface layer B and the surface layer C was an antiblocking agent with a pore volume of zero, and therefore the dropout rate of the antiblocking agent in the surface layer B and the surface layer C was high, resulting in stains on the entire surface of the guide roll. Furthermore, when an aluminum vapor-deposited film was provided on the surface layer B, the oxygen permeability of the aluminum vapor-deposited film was high and the gas barrier property was poor.
• the biaxially oriented polypropylene film of the present invention has excellent thermal dimensional stability and mechanical strength, excellent workability when forming a vapor deposition layer or a coating layer on the biaxially oriented polypropylene film, and excellent adhesion to the vapor deposition layer or the coating layer, so it can be used as a base film for various processing.
• a layer made of metal and/or metal oxide is formed on the biaxially oriented polypropylene film of the present invention, a film with high gas barrier properties can be obtained, which is preferable.
• Such processed films can be used for food packaging, labels, industrial films, etc., and are industrially useful.

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• 2024
  • 2024-01-10 WO PCT/JP2024/000253 patent/WO2024161918A1/ja not_active Ceased
  • 2024-01-10 JP JP2024574358A patent/JPWO2024161918A1/ja active Pending
  • 2024-01-17 TW TW113101787A patent/TW202438313A/zh unknown

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