Manufacturing method of pellet and manufacturing apparatus of pellet

Abstract

To provide a manufacturing method of pellets capable of comparatively reducing fish eye formation and a manufacturing apparatus of pellets capable of manufacturing the pellets.SOLUTION: A manufacturing method of pellets including an olefin-based polymer and an anti-blocking agent includes the following steps of 1 and 2. The step 1 is a measurement and transportation step in which an olefin-based polymer and an anti-blocking agent are measured, and the olefin-based polymer and the anti-blocking agent of measured specified quantities are supplied to a transportation feeder from different spots and transported by the transportation feeder. The step 2 is a pelletizing step in which the olefin-based polymer and the anti-blocking agent are supplied from the transportation feeder from the same spot to a pelletizer, the supplied olefin-based polymer is thermo-fused while the olefin-based polymer and the anti-blocking agent are kneaded in a pelletizer to produce a kneaded product, then the kneaded product is discharged from the pelletizer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pellet manufacturing method and a pellet manufacturing apparatus. [Background technology]

[0002] Conventionally, films on which aluminum is vapor-deposited (referred to as "aluminum vapor-deposited films") are lightweight and have excellent barrier properties, and therefore are suitably used as packaging materials for light food packaging, etc. Polyolefin films are used as films on which aluminum is vapor-deposited (referred to as "raw film").

[0003] Polyolefin films are generally made from pellets of a polyolefin resin composition in which an antiblocking agent such as inorganic fine powder is blended with a polyolefin resin in order to improve the sliding property between films and the blocking resistance. For example, Patent Document 1 discloses a method for producing pellets of such polyolefin resin composition, in which a predetermined amount of polypropylene resin and additives such as an antiblocking agent are mixed using a Henschel mixer, and then the mixture is fed to a twin-screw extruder for melt-kneading. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-292687 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the original film is required to have few fisheyes. If fisheyes are present in the original film, pinholes may appear in the aluminum vapor deposition film, resulting in reduced barrier properties.

[0006] However, the method described in Patent Document 1 has a problem in that poor dispersion occurs when the polyolefin resin and the antiblocking agent are mixed, and fish eyes tend to occur in the obtained film.

[0007] The present invention has been made in consideration of such problems, and an object of the present invention is to provide a pellet manufacturing method that can relatively reduce the occurrence of fisheyes, and a pellet manufacturing apparatus that can manufacture such pellets. [Means for solving the problem]

[0008] The method for producing pellets according to the present invention is a method for producing pellets containing an olefin polymer and an antiblocking agent, and includes the following steps 1 and 2. Step 1: A weighing and conveying step of weighing the olefin polymer and the antiblocking agent, respectively, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent from separate locations to a conveying feeder and conveying them by the conveying feeder. Step 2: A granulation step in which the olefin polymer and the antiblocking agent are each supplied from the same location to a granulator from a conveying feeder, the supplied olefin polymer is heated and melted while the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator.

[0009] The pellet manufacturing apparatus according to the present invention includes a measuring and conveying device having a measuring section for measuring each of an olefin polymer and an antiblocking agent, and a conveying feeder to which the measured amounts of the olefin polymer and the antiblocking agent are supplied and which conveys the supplied olefin polymer and antiblocking agent; a granulator which receives an olefin polymer and an antiblocking agent from a conveying feeder of the metering and conveying device, kneads the olefin polymer and the antiblocking agent while heating and melting the supplied olefin polymer to form a kneaded mixture, and discharges the kneaded mixture; Equipped with The conveying feeder has separate locations to which the olefin polymer and the antiblocking agent are supplied, whereas the granulator has the same location to which the olefin polymer and the antiblocking agent are supplied. Effect of the Invention

[0010] According to the present invention, it is possible to provide a pellet manufacturing method capable of relatively reducing the occurrence of fisheyes, and a pellet manufacturing apparatus capable of manufacturing such pellets. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a pellet production method and production apparatus according to one aspect of an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating a pellet production method and production apparatus according to another aspect of the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited to the following embodiment. In the following drawings, the same or corresponding parts are given the same reference characters and their description will not be repeated.

[0013] 1. Pellets manufacturing method The method for producing pellets according to this embodiment is a method for producing pellets containing an olefin polymer and an antiblocking agent, and includes the following steps 1 and 2. Step 1: A weighing and conveying step of weighing the olefin polymer and the antiblocking agent, respectively, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent from separate locations to a conveying feeder and conveying them by the conveying feeder. Step 2: A granulation step in which the olefin polymer and the antiblocking agent are each supplied from the same location to a granulator from a conveying feeder, the supplied olefin polymer is heated and melted while the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator.

[0014] In one aspect, the method for producing pellets according to this embodiment includes the following steps 1(1) and 2(1). Step 1(1): A weighing and conveying step of weighing the olefin polymer and the antiblocking agent, respectively, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent to a single conveying feeder from different positions thereof, and conveying the materials by the conveying feeder. Step 2(1): A granulation step in which an olefin polymer and an antiblocking agent are each supplied from the same location to a granulator through one conveying feeder, and while the supplied olefin polymer is heated and melted, the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator.

[0015] One embodiment will be specifically described with reference to Fig. 1. As shown in Fig. 1, in step 1(1), the olefin polymer and the antiblocking agent are each weighed, and the weighed predetermined amounts of the olefin polymer and the antiblocking agent are each supplied to a single conveying feeder 23 from different positions of the single conveying feeder 23 and conveyed by the conveying feeder 23. More specifically, the olefin polymer is supplied to the upstream side of a single conveying feeder 23, and the antiblocking agent is supplied to the downstream side.

[0016] As shown in FIG. 1 , in step 2(1), an olefin polymer and an antiblocking agent are each supplied from the same location to a granulator 3 through a single conveying feeder 23, and while the supplied olefin polymer is heated and melted, the olefin polymer and the antiblocking agent are kneaded in the granulator 3 to form a kneaded mixture, which is then discharged from the granulator 3.

[0017] In another aspect, the method for producing pellets according to the present embodiment includes the following steps 1(2) and 2(2). Step 1(2): A weighing and conveying step of weighing the olefin polymer and the antiblocking agent in predetermined amounts, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent to two conveying feeders, respectively, and conveying them by the conveying feeders. Step 2(2): A granulation step in which an olefin polymer and an antiblocking agent are supplied from two conveying feeders to a granulator from the same locations, and while the supplied olefin polymer is heated and melted, the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator.

[0018] Another embodiment will be specifically described with reference to Fig. 2. As shown in Fig. 2, in step 1(2), the olefin polymer and the antiblocking agent are each weighed, and the weighed predetermined amounts of the olefin polymer and the antiblocking agent are supplied to two conveying feeders 23, 23, respectively, and conveyed by the conveying feeders 23, 23. That is, the olefin polymer and the antiblocking agent are each supplied to the conveying feeders from different locations.

[0019] As shown in FIG. 2 , in step 2(2), the olefin polymer and the antiblocking agent are supplied from two conveying feeders 23, 23 to the granulator 3 from the same locations, and while the supplied olefin polymer is heated and melted, the olefin polymer and the antiblocking agent are kneaded in the granulator 3 to form a kneaded mixture, which is then discharged from the granulator 3.

[0020] The pellet production method according to the present embodiment may further include a mixing step of mixing the olefin polymer and at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate regulator, prior to step 1. When the pellet production method according to the present embodiment includes the mixing step, the additive is fed to a conveying feeder together with the olefin polymer in step 1. The mixing step can be carried out using a mixer such as a Henschel mixer or a Nauta mixer.

[0021] In the pellet production method according to this embodiment, step 1 may further include weighing at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier, and supplying the weighed predetermined amount of the additive to a conveying feeder from a position separate from the olefin polymer and the antiblocking agent, and conveying the additive by the conveying feeder.

[0022] More specifically, for example, in the above-mentioned one embodiment, when the additive is supplied to one transport feeder 23, the additive may be supplied upstream of the olefin polymer, downstream of the antiblocking agent, or downstream of the olefin polymer and upstream of the antiblocking agent. The additive is preferably supplied downstream of the olefin polymer and upstream of the antiblocking agent. Also, for example, in the above-mentioned other embodiment, a transport feeder for supplying the additive may be provided, and the olefin polymer, the antiblocking agent, and the additive may be supplied to each of the three transport feeders and transported by the transport feeders.

[0023] Examples of the transport feeder 23 include a screw type feeder, a conveyor type feeder, etc. Among these, the transport feeder 23 is preferably a screw type feeder that has a screw arranged along the transport direction and transports the transported object by rotation of the screw.

[0024] [Olefin polymer] The olefin-based polymer is an olefin homopolymer or an olefin-based copolymer containing 50% by mass or more of a structural unit derived from an olefin. The pellet may contain at least one selected from the group consisting of an olefin homopolymer and an olefin-based copolymer as the olefin-based polymer. Examples of the olefin-based polymer include a propylene-based polymer and an ethylene-based polymer. The olefin-based polymer is preferably a propylene-based polymer whose main component is a structural unit derived from propylene.

[0025] The propylene-based polymer is a polymer containing more than 50% by mass of structural units derived from propylene, and may be a propylene homopolymer or a propylene-based copolymer containing more than 50% by mass of structural units derived from propylene. Examples of the propylene-based copolymer include copolymers of propylene with ethylene and / or an α-olefin having 4 to 10 carbon atoms. The propylene-based polymer may be a so-called heterophasic propylene polymerization material containing both a propylene homopolymer and a propylene-based copolymer.

[0026] The ethylene-based polymer is a polymer containing more than 50% by mass of structural units derived from ethylene, and may be an ethylene homopolymer or an ethylene-based copolymer containing more than 50% by mass of structural units derived from ethylene. Examples of the ethylene-based copolymer include a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, and a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms substituted with an alicyclic compound. The ethylene-based polymer may contain both an ethylene homopolymer and an ethylene-based copolymer.

[0027] Olefin polymers are carbon-14 ( 14 C) as a constituent element, or may be one that has been material recycled (mechanically recycled).

[0028] Carbon 14 ( 14The concentration of carbon-14(C) is calculated as pMC (percentage of mordern carbon) by the Accelerator Mass Spectrometry (AMS) method specified in ISO 16620-2:2019. Carbon dioxide in the atmosphere contains carbon-14( 14 C) in a certain proportion, so plants that grow by absorbing carbon dioxide from the atmosphere, such as corn and trees, contain carbon-14( 14 It is known that carbon-14(C) is contained in fossil fuels such as petroleum, which are thought to have been stored underground for a long time. 14 It is also known that the propylene polymer contains almost no carbon-14 (C). Therefore, by using plant-derived substances as the raw material for the monomer used in the production of propylene polymer, the constituent elements of the propylene polymer can be made to contain almost no carbon-14 ( 14 C) may be contained.

[0029] In the production of olefin polymers, fossil resource-derived monomers (ethylene, propylene, 1-butene, 1-hexene, etc.), plant-derived monomers (ethylene, propylene, 1-butene, 1-hexene, etc.), chemically recycled monomers (ethylene, propylene, 1-butene, 1-hexene, etc.), etc. can be used, and these can be used in combination of two or more. Specific monomer combinations include, for example, fossil resource-derived propylene / plant-derived propylene / chemically recycled propylene, fossil resource-derived propylene / plant-derived propylene / chemically recycled propylene / fossil resource-derived ethylene / plant-derived ethylene / chemically recycled ethylene, fossil resource-derived propylene / plant-derived propylene / chemically recycled propylene / fossil resource-derived 1-butene / plant-derived 1-butene / chemically recycled 1-butene, etc.

[0030] Fossil resource-derived monomers are derived from carbon from underground resources such as petroleum, coal, and natural gas, and generally contain carbon-14( 14C) is hardly contained. Methods for producing monomers derived from fossil resources include known methods, such as cracking petroleum-derived naphtha and ethane, and dehydrogenating ethane and propane to produce olefins.

[0031] Plant-derived monomers are derived from carbon that circulates on the earth's surface as plants and animals, and generally contain a certain percentage of carbon-14( 14 Examples of methods for producing plant-derived monomers include known methods, such as cracking of bionaphtha, vegetable oil, animal oil, etc., dehydrogenation of biopropane, methods of separating alcohol from fermented products such as sugar extracted from plant raw materials such as sugarcane and corn, and subjecting it to a dehydration reaction (JP-T 2010-511634 A, JP-T 2011-506628 A, JP-T 2013-503647 A, etc.), and methods of subjecting ethylene obtained from plant-derived ethanol to a metathesis reaction with n-butene (WO 2007 / 055361 A, etc.).

[0032] Chemical recycling monomers are derived from carbon generated by the decomposition and combustion of waste materials. 14 C) content varies depending on the waste. Methods for producing chemical recycling monomers include known methods, such as a method of pyrolyzing waste plastics (JP Patent Publication No. 2017-512246, etc.), a method of cracking waste vegetable oil, waste animal oil, etc. (JP Patent Publication No. 2018-522087, etc.), and a method of gasifying, converting to alcohol, and dehydrating waste such as food waste, biomass waste, food waste, waste oil, waste wood, waste paper, and waste plastics (JP Patent Publication No. 2019-167424, International Publication No. 2021 / 006245, etc.).

[0033] When two or more of fossil resource-derived olefins, plant-derived olefins, and chemically recycled olefins are used, the olefins produced individually may be mixed and used in combinations such as fossil resource-derived olefins / plant-derived olefins, fossil resource-derived olefins / chemically recycled olefins, plant-derived olefins / chemically recycled olefins, and fossil resource-derived olefins / plant-derived olefins / chemically recycled olefins. In addition, a mixture of the above olefin combinations may be produced by using a mixture of combinations such as fossil resource-derived compounds / plant-derived compounds, fossil resource-derived compounds / chemically recycled compounds, plant-derived compounds / chemically recycled compounds, and fossil resource-derived compounds / plant-derived compounds / chemically recycled compounds as raw materials or intermediates in the olefin production process.

[0034] Carbon 14 ( 14 From the viewpoint of reducing the environmental load, the concentration of carbon-14 (C) contained in the olefin polymer is preferably 0.2 pMC(%) or more, more preferably 0.5 pMC(%) or more, even more preferably 1 pMC(%) or more, still more preferably 5 pMC(%) or more, and particularly preferably 10 pMC(%) or more. 14 From the viewpoint of cost, the concentration of carbon-14 (C) contained in the olefin polymer is preferably 99 pMC(%) or less, more preferably 95 pMC(%) or less, even more preferably 90 pMC(%) or less, still more preferably 70 pMC(%) or less, and particularly preferably 50 pMC(%) or less. 14 The concentration of C) can be adjusted by changing the ratio of the fossil resource-derived olefin, the plant-derived olefin, and the chemically recycled olefin used in the production of the olefin-based polymer.

[0035] <Propylene-based polymer> The isotactic pentad fraction of the propylene-based polymer is preferably 0.961 or more, more preferably 0.975 or more, and even more preferably 0.980 or more. The isotactic pentad fraction of the propylene-based polymer is preferably 1.000 or less, and more preferably 0.995 or less.

[0036] The isotactic pentad fraction means the isotactic fraction in pentad units. That is, the isotactic pentad fraction indicates the content ratio of a structure in which five consecutive structural units derived from propylene are meso-bonded when viewed in pentad units. When the target component is a copolymer, the isotactic pentad fraction refers to a value measured for the chain of structural units derived from propylene.

[0037] The isotactic pentad fraction is 13 This is a value measured by C-NMR spectroscopy. 13 The ratio of the area of ​​the mmmm peak to the area of ​​all absorption peaks in the methyl carbon region obtained by C-NMR spectrum is defined as the isotactic pentad fraction. 13 The method for measuring the isotactic pentad fraction by C-NMR spectroscopy is described, for example, in Macromolecules, 6, 925 (1973) by A. Zambelli et al. 13 The assignment of absorption peaks obtained by C-spectrum is based on the description in Macromolecules, 8, 687 (1975).

[0038] The isotactic pentad fraction of the propylene-based polymer can be adjusted to the above range by appropriately selecting a catalyst, a donor, polymerization conditions, etc. Also, a propylene-based polymer having a desired isotactic pentad fraction can be obtained from a commercial product.

[0039] The melt flow rate (MFR) of the propylene polymer is preferably 0.1 g / 10 min or more and 300 g / 10 min or less, more preferably 1 g / 10 min or more and 100 g / 10 min or less, and even more preferably 1 g / 10 min or more and 10 g / 10 min or less.

[0040] The melt flow rate (MFR) of a propylene-based polymer is measured by Method A under conditions of a temperature of 230° C. and a load of 2.16 kg in accordance with the method specified in JIS K7210-1:2014 and K7210-2:2014.

[0041] (Propylene homopolymer) The intrinsic viscosity number ([η]) of the propylene homopolymer is preferably 0.10 dL / g or more and 4.00 dL / g or less, more preferably 0.50 dL / g or more and 3.00 dL / g or less, and even more preferably 0.70 dL / g or more and 2.00 dL / g or less.

[0042] In this specification, the intrinsic viscosity (unit: dL / g) is a value measured at a temperature of 135° C. using tetralin as a solvent by the following method.

[0043] Using an Ubbelohde viscometer, the reduced viscosity is measured at three concentrations: 0.1 g / dL, 0.2 g / dL, and 0.5 g / dL. The reduced viscosity is plotted against the concentration, and the intrinsic viscosity is calculated by the extrapolation method in which the concentration is extrapolated to zero. The method for calculating the intrinsic viscosity by the extrapolation method is described, for example, in page 491 of "Polymer Solutions, Polymer Experiments 11" (published by Kyoritsu Publishing Co., Ltd. in 1982).

[0044] The molecular weight distribution (Mw / Mn) of the propylene homopolymer is preferably 2.0 or more, more preferably 3.0 or more. The molecular weight distribution of the propylene homopolymer is preferably 15.0 or less, more preferably 10.0 or less. The molecular weight distribution of the propylene homopolymer is preferably 2.0 or more and 15.0 or less, more preferably 3.0 or more and 10.0 or less.

[0045] In this specification, the molecular weight distribution means the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), calculated using the weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC) under the following conditions. Equipment: Tosoh Corporation HLC-8121 GPC / HT Separation column: 3 GMHHR-H(S)HT, manufactured by Tosoh Corporation Measurement temperature: 140℃ Carrier: Orthodichlorobenzene Flow rate: 1.0mL / min Sample concentration: Approximately 1 mg / mL Sample injection volume: 400 μL Detector: Differential Refraction Calibration curve creation method: Use standard polystyrene

[0046] The propylene homopolymer can be produced, for example, by carrying out a polymerization step of polymerizing propylene using a polymerization catalyst.

[0047] Examples of the polymerization catalyst include Ziegler type catalysts; Ziegler-Natta type catalysts; catalysts containing a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane; catalysts containing a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with the transition metal compound to form an ionic complex, and an organoaluminum compound; and catalysts modified by supporting a catalyst component (a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, an organoaluminum compound, etc.) on inorganic particles (silica, clay minerals, etc.).

[0048] Examples of the polymerization catalyst include catalysts described in JP-A-61-218606, JP-A-5-194685, JP-A-7-216017, JP-A-9-316147, JP-A-10-212319, JP-A-2004-182981, JP-A-2010-168545, and JP-A-2011-246699.

[0049] Furthermore, a polymer obtained by prepolymerizing propylene in the presence of the above polymerization catalyst can also be used as the polymerization catalyst.

[0050] Examples of the polymerization method include bulk polymerization, solution polymerization, and gas phase polymerization. Here, bulk polymerization refers to a method in which polymerization is carried out using an olefin that is liquid at the polymerization temperature as a medium. Solution polymerization refers to a method in which polymerization is carried out in an inert hydrocarbon solvent such as propane, butane, isobutane, pentane, hexane, heptane, or octane. Gas phase polymerization refers to a method in which a gaseous monomer is used as a medium and the gaseous monomer is polymerized in the medium.

[0051] The polymerization method may be, for example, a batch method, a continuous method, or a combination thereof. The polymerization method may be a multi-stage method in which a plurality of polymerization reaction vessels are connected in series.

[0052] From the viewpoint of industrial and economical superiority, the polymerization method is preferably a continuous gas phase polymerization method or a bulk-gas phase polymerization method in which a bulk polymerization method and a gas phase polymerization method are carried out continuously.

[0053] Various conditions in the polymerization step (polymerization conditions such as polymerization temperature, polymerization pressure, monomer concentration, catalyst input amount, and polymerization time) may be appropriately determined depending on the molecular structure of the desired polymer.

[0054] In the method for producing a propylene homopolymer, other steps may be carried out before or after the polymerization step. For example, after the polymerization step, the polymer may be dried at a temperature equal to or lower than the melting temperature of the polymer, if necessary, in order to remove residual solvent contained in the polymer and ultralow molecular weight oligomers produced as by-products during production. Examples of the drying method include the methods described in JP-A-55-75410 and JP-A-2565753.

[0055] (Random copolymer of propylene and monomers other than propylene) The random copolymer of propylene and a monomer other than propylene contains structural units derived from propylene and structural units derived from a monomer other than propylene, and preferably contains 0.01% by mass or more and 20% by mass or less of structural units derived from a monomer other than propylene, based on 100% by mass of the total mass of the copolymer.

[0056] Examples of monomers other than propylene include ethylene and α-olefins having 4 to 12 carbon atoms. In this specification, α-olefins are aliphatic unsaturated hydrocarbons having a carbon-carbon unsaturated double bond at the α-position. Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 4-methyl-1-hexene.

[0057] The monomer other than propylene is preferably at least one selected from the group consisting of ethylene and α-olefins having 4 to 10 carbon atoms, more preferably at least one selected from the group consisting of ethylene, 1-butene, 1-hexene, and 1-octene, and even more preferably at least one selected from the group consisting of ethylene and 1-butene.

[0058] Examples of random copolymers of propylene and monomers other than propylene include propylene-ethylene random copolymers, propylene-1-butene random copolymers, propylene-1-hexene random copolymers, propylene-1-octene random copolymers, propylene-ethylene-1-butene random copolymers, propylene-ethylene-1-hexene random copolymers, and propylene-ethylene-1-octene random copolymers.

[0059] The random copolymer of propylene and a monomer other than propylene has an intrinsic viscosity ([η]) of preferably 0.10 dL / g or more and 4.00 dL / g or less, more preferably 0.50 dL / g or more and 3.00 dL / g or less, and even more preferably 0.70 dL / g or more and 2.00 dL / g or less.

[0060] The random polymer of propylene and a monomer other than propylene has a molecular weight distribution (Mw / Mn) of preferably 2.0 or more, more preferably 3.0 or more. The molecular weight distribution is preferably 10.0 or less, more preferably 7.0 or less. The random polymer of propylene and a monomer other than propylene has a molecular weight distribution of preferably 2.0 or more and 10.0 or less, more preferably 3.0 or more and 7.0 or less.

[0061] The random copolymer of propylene and a monomer other than propylene can be produced, for example, by polymerizing propylene and a monomer other than propylene according to the polymerization catalyst, polymerization method, polymerization system, and polymerization conditions that can be used in the production of the above-mentioned propylene homopolymer.

[0062] (Heterophagic propylene polymer material) The heterophasic propylene polymerization material is a mixture containing a polymer I containing 80% by mass or more of structural units derived from propylene (wherein the total mass of the polymer I is taken as 100% by mass) and a polymer II containing structural units derived from at least one α-olefin selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms and structural units derived from propylene.

[0063] The heterophasic propylene polymer material can be produced, for example, by carrying out a first polymerization step of polymerizing polymer I and a second polymerization step of polymerizing polymer II. These polymerization steps can be carried out according to the polymerization catalyst, polymerization method, polymerization scheme, and polymerization conditions that can be used in the production of the above-mentioned propylene homopolymer.

[0064] The heterophasic propylene polymerization material may be such that the sum of polymer I and polymer II contained in the heterophasic propylene polymerization material is 100% by mass relative to the total mass of the heterophasic propylene polymerization material (100% by mass).

[0065] As described above, polymer I contains 80% by mass or more of structural units derived from propylene (where the total mass of polymer I is taken as 100% by mass). Polymer I may be, for example, a propylene homopolymer, or may contain structural units derived from monomers other than propylene. When polymer I contains structural units derived from monomers other than propylene, the content of such structural units may be, for example, 0.01% by mass or more and less than 20% by mass with respect to the total mass of polymer I, 100% by mass.

[0066] <Ethylene-α-olefin copolymer> The olefin polymer may be an ethylene-α-olefin copolymer.

[0067] The ethylene-α-olefin copolymer may be an ethylene-α-olefin random copolymer. Note that the ethylene-α-olefin copolymer refers to a copolymer containing structural units derived from ethylene and structural units derived from an α-olefin having 4 or more carbon atoms, and substantially not containing structural units derived from propylene.

[0068] The ethylene-α-olefin copolymer may have a total content of structural units derived from ethylene and structural units derived from an α-olefin having 4 or more carbon atoms of 100% by mass, relative to the total mass of the copolymer (100% by mass).

[0069] Examples of the α-olefins having 4 or more carbon atoms include α-olefins having 4 to 12 carbon atoms. Examples of the α-olefins having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene. The α-olefins having 4 to 12 carbon atoms are preferably 1-butene, 1-hexene, or 1-octene. The α-olefins having 4 to 12 carbon atoms may be α-olefins having a cyclic structure, such as vinylcyclopropane and vinylcyclobutane.

[0070] Examples of ethylene-α-olefin copolymers include ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-1-decene copolymers, ethylene-(3-methyl-1-butene) copolymers, and copolymers of ethylene and an α-olefin having a cyclic structure.

[0071] In the ethylene-α-olefin copolymer, the content of structural units derived from α-olefins having 4 or more carbon atoms is preferably 1% by mass or more and 49% by mass or less, more preferably 5% by mass or more and 49% by mass or less, and even more preferably 24% by mass or more and 49% by mass or less, relative to the total mass of the ethylene-α-olefin copolymer (100% by mass).

[0072] The density of the ethylene-α-olefin copolymer is preferably 0.85 g / cm 3 More than 0.89g / cm 3 More preferably, it is 0.85 g / cm 3 More than 0.88g / cm 3 More preferably, it is 0.85 g / cm or less. 3 More than 0.87g / cm 3 The following is the result.

[0073] The melt flow rate (MFR) of the ethylene-α-olefin copolymer is preferably 0.1 g / 10 min or more and 80 g / 10 min or less. The melt flow rate (MFR) of the ethylene-α-olefin copolymer is measured by the A method under the conditions of a temperature of 190° C. and a load of 2.16 kg according to the method specified in JIS K7210-1:2014 and K7210-2:2014.

[0074] When the ethylene-α-olefin copolymer is contained, the content thereof is preferably 80 parts by mass or more, and more preferably 90 parts by mass or more, based on 100 parts by mass of the olefin polymer.

[0075] Ethylene-α-olefin copolymers can be produced by polymerizing ethylene and an α-olefin having 4 or more carbon atoms using a polymerization catalyst.

[0076] Examples of the polymerization catalyst include homogeneous catalysts such as metallocene catalysts, and Ziegler-Natta type catalysts.

[0077] Examples of homogeneous catalysts include catalysts containing a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring and an alkylaluminoxane; catalysts containing a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that reacts with the transition metal compound to form an ionic complex, and an organoaluminum compound; and catalysts modified by supporting a catalyst component (a compound of a transition metal of Group 4 of the periodic table having a cyclopentadienyl ring, a compound that forms an ionic complex, an organoaluminum compound, etc.) on inorganic particles (silica, clay minerals, etc.).

[0078] An example of the Ziegler-Natta type catalyst is a catalyst that combines a titanium-containing solid transition metal component with an organometallic component.

[0079] The ethylene-α-olefin copolymer may be a commercially available product. Examples of commercially available ethylene-α-olefin copolymers include Engage (registered trademark) manufactured by Dow Chemical Japan, Tafmer (registered trademark) manufactured by Mitsui Chemicals, Neozex (registered trademark) and Ultzex ​​(registered trademark) manufactured by Prime Polymer Co., Ltd., Excellen FX (registered trademark), Sumikathen (registered trademark), and Esprene SPO (registered trademark) manufactured by Sumitomo Chemical Co., Ltd.

[0080] [Anti-blocking agent] Examples of the antiblocking agent include fine particles such as inorganic fine particles, organic fine particles, etc. The antiblocking agent is preferably fine particles composed of at least one selected from the group consisting of silicon dioxide, aluminosilicate, magnesium silicate, aluminum silicate, aluminum borate, and calcium carbonate, or crosslinked polymer fine particles composed of a styrene derivative monomer, a radical polymerizable monomer unit, and a crosslinking agent, and more preferably fine particles composed of silicon dioxide.

[0081] Examples of methods for producing fine particles made of silicon dioxide include known methods such as wet methods and dry methods. The wet method is preferred from the viewpoint of ease of controlling the physical properties.

[0082] The wet method is carried out, for example, as follows.

[0083] By mixing sodium silicate made from high-purity silica sand with sulfuric acid, a silicate sol is produced and primary particles are formed. The primary particles are subjected to a sol-gel polymerization reaction to form three-dimensional silicon dioxide aggregates, resulting in fine particles made of silicon dioxide.

[0084] In the wet method, by changing the conditions for forming the primary particles, it is possible to obtain fine particles made of silicon dioxide having desired properties. Note that fine particles made of naturally occurring silicon dioxide are not suitable because it is difficult to obtain the desired properties.

[0085] The fine particles composed of silicon dioxide may be commercially available products.

[0086] The fine particles composed of silicon dioxide preferably contain 40 mass % or more of silicon dioxide in the crystal structure.

[0087] The fine particles composed of silicon dioxide may be magnesium silicate, aluminum silicate, or calcium aluminum silicate.

[0088] The antiblocking agent may be surface-treated using a surface treatment agent. Examples of the surface treatment agent include surfactants, metal soaps, organic acids such as acrylic acid, oxalic acid, citric acid, and tartaric acid, higher alcohols, esters, silicones, fluororesins, silane coupling agents, condensed phosphates such as sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, and sodium trimetaphosphate, pH adjusters, and organic stabilizers. Among these, the surface treatment agent is preferably an organic acid such as acrylic acid, oxalic acid, citric acid, and tartaric acid, and more preferably citric acid. The method of surface treatment is not particularly limited, and may be a known method such as surface spraying or immersion.

[0089] The shape of the particles of the antiblocking agent is not particularly limited, and may be, for example, spherical, angular, columnar, needle-like, plate-like, or irregular.

[0090] The weight average particle diameter of the antiblocking agent, as measured by a Coulter counter method, is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 10 μm or less, and even more preferably 2 μm or more and 5 μm or less, from the viewpoint of enhancing the effect of improving blocking resistance and from the viewpoint of transparency.

[0091] The bulk density of the antiblocking agent is preferably 0.01 g / ml or more and 1 g / ml or less, more preferably 0.01 g / ml or more and 0.5 g / ml or less, and even more preferably 0.05 g / ml or more and 0.2 g / ml or less, from the viewpoint of enhancing the effect of improving blocking resistance and from the viewpoint of scratch resistance.

[0092] The BET specific surface area of ​​the antiblocking agent is preferably 30 m from the viewpoint of improving the blocking resistance and transparency. 2 / g or more 700m 2 / g or less, more preferably 100m 2 / g or more 400m 2 / g or less, more preferably 150m 2 / g or more 300m 2 / g or less.

[0093] The pore volume of the antiblocking agent is preferably 0.04 ml / g or more and 3 ml / g or less, more preferably 0.4 ml / g or more and 2 ml / g or less, from the viewpoint of simultaneously imparting particularly good blocking resistance and scratch resistance to the resulting polyolefin film.

[0094] The whiteness of the antiblocking agent is preferably 80 or more, and more preferably 95 or more, from the viewpoint of imparting particularly good edge color to the resulting polyolefin film.

[0095] The weight average particle size, BET specific surface area, pore volume, and whiteness of the antiblocking agent are measured by the following methods. (1) Weight average particle size: Determined by a laser counter method. (2) BET specific surface area: It is determined by measuring by a continuous volumetric method using an automatic gas adsorption / desorption analyzer (BECKMAN COULTER Omnisorb 360). (3) Pore volume: It is determined by measuring by a continuous volumetric method using an automatic gas adsorption / desorption analyzer (BECKMAN COULTER Omnisorb 360). (4) Whiteness: Determined according to the method specified in JIS P 8123.

[0096] From the viewpoint of producing pellets that can relatively reduce the occurrence of fisheyes, the mass ratio of the antiblocking agent is preferably from 0.01 to 20 parts by mass, more preferably from 0.01 to 10 parts by mass, and even more preferably from 0.05 to 1 part by mass, relative to 100 parts by mass of the olefin-based polymer.

[0097] In the pellet production method according to the present embodiment, in step 1, the olefin polymer and the antiblocking agent are preferably in the form of powder.

[0098] 2. Pellet manufacturing equipment The pellet manufacturing apparatus according to this embodiment includes a weighing and conveying device and a granulator.

[0099] (Weight conveying device) The metering and conveying device has a metering section for metering the olefin polymer, a metering section for metering the antiblocking agent, and a conveying feeder for conveying the supplied olefin polymer and antiblocking agent. The conveying feeder has separate locations for supplying the olefin polymer and the antiblocking agent. The metering and conveying device may further have a metering section for metering at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier.

[0100] The above step 1 is carried out by using a weighing and conveying device.

[0101] (granulator) The granulator is supplied with an olefin polymer and an antiblocking agent from a conveying feeder of a metering conveying device, kneads the olefin polymer and the antiblocking agent while heating and melting the supplied olefin polymer to form a kneaded product, and discharges the kneaded product. The granulator is supplied with the olefin polymer and the antiblocking agent at the same location. When the granulator further supplies at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier, the olefin polymer, the antiblocking agent, and the additive are supplied to the same location.

[0102] The above step 2 is carried out by using a granulator.

[0103] In one aspect, the pellet manufacturing apparatus according to this embodiment includes a measuring and conveying device having a measuring section which measures each of the olefin polymer and the antiblocking agent, and one conveying feeder to which the measured amounts of the olefin polymer and the antiblocking agent are supplied and which conveys the supplied olefin polymer and antiblocking agent, and a granulator to which the olefin polymer and the antiblocking agent are supplied from the one conveying feeder of the measuring and conveying device, which heats and melts the supplied olefin polymer while kneading the olefin polymer and the antiblocking agent to form a kneaded material, and which discharges the kneaded material, wherein the one conveying feeder has different locations to which the olefin polymer and the antiblocking agent are supplied, and the granulator has the same location to which the olefin polymer and the antiblocking agent are supplied.

[0104] One embodiment will be specifically described with reference to Fig. 1. As shown in Fig. 1, the weighing and conveying device 2 has a weighing section 21 that weighs the olefin polymer, a weighing section 22 that weighs the antiblocking agent, and one conveying feeder 23 that conveys the supplied olefin polymer and antiblocking agent. More specifically, the weighing section 21 is disposed upstream of one conveying feeder 23 so as to be able to supply the olefin polymer, and the weighing section 22 is disposed downstream so as to be able to supply the antiblocking agent. That is, the one conveying feeder 23 has separate locations to which the olefin polymer and the antiblocking agent are supplied.

[0105] In another aspect, the pellet manufacturing apparatus according to this embodiment includes a measuring and conveying device having a measuring section which measures the olefin polymer and the antiblocking agent, respectively, and two conveying feeders to which the measured predetermined amounts of the olefin polymer and the antiblocking agent are respectively supplied and which convey the supplied olefin polymer and antiblocking agent, and a granulator to which the olefin polymer and the antiblocking agent are supplied from the two conveying feeders of the measuring and conveying device, which heats and melts the supplied olefin polymer while kneading the olefin polymer and the antiblocking agent to form a kneaded material, and which discharges the kneaded material, wherein the two conveying feeders have different locations to which the olefin polymer and the antiblocking agent are supplied, and the granulator has the same location to which the olefin polymer and the antiblocking agent are supplied.

[0106] Another embodiment will be specifically described with reference to Fig. 2. As shown in Fig. 2, the weighing and conveying device 2 has a weighing section 21 that weighs the olefin polymer, a weighing section 22 that weighs the antiblocking agent, and two conveying feeders 23, 23 that convey the supplied olefin polymer and antiblocking agent, respectively. That is, the two conveying feeders 23, 23 are supplied to different locations for the olefin polymer and the antiblocking agent.

[0107] As shown in FIGS. 1 and 2, the granulator 3 has, for example, a supply port 31, a cylinder 32, a screw 33, and a discharge port .

[0108] Specifically, the olefin polymer and the antiblocking agent conveyed from the conveying feeder 23 are each supplied from a supply port 31 into the inside of a cylinder 32. That is, the granulator 3 has the same supply location for the olefin polymer and the antiblocking agent. The supplied olefin polymer and the antiblocking agent are kneaded by a screw 33 provided inside the cylinder 32 while the olefin polymer is heated and melted inside the cylinder 32, to form a kneaded product. The kneaded product is then discharged from a discharge port 34 as pellets.

[0109] The screw 33 may be a single screw or multiple screws. From the viewpoint of achieving both the dispersibility and extrusion ability of the antiblocking agent, the screw 33 preferably has at least two screws, and more preferably has two screws. When the screw has at least two screws, the rotation directions of the individual screws may be the same or different. From the viewpoint of achieving both the dispersibility and extrusion ability of the antiblocking agent, the rotation directions of the individual screws are preferably the same.

[0110] The temperature inside the cylinder 32 is preferably equal to or higher than the melting point of the olefin polymer, and more preferably, is 40° C. to 160° C. higher than the melting point of the olefin polymer.

[0111] The supply port 31 may be equipped with a hopper.

[0112] The present invention includes the following aspects. [1] A method for producing pellets containing an olefin polymer and an antiblocking agent, the method comprising the following steps 1 and 2: Step 1: A weighing and conveying step of weighing the olefin polymer and the antiblocking agent, respectively, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent from separate locations to a conveying feeder and conveying them by the conveying feeder. Step 2: A granulation step in which the olefin polymer and the antiblocking agent are each supplied from the same location to a granulator from a conveying feeder, the supplied olefin polymer is heated and melted while the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator. [2] The method for producing pellets according to [1], wherein the conveying feeder is a screw-type feeder having a screw arranged along the conveying direction and conveying the material by rotation of the screw. [3] The method for producing pellets according to [1] or [2], wherein in step 1, the olefin polymer and the antiblocking agent are in the form of powder. [4] The method for producing pellets according to any one of [1] to [3], wherein a mass ratio of the antiblocking agent is from 0.01 parts by mass to 20 parts by mass relative to 100 parts by mass of the olefin polymer. [5] The method for producing pellets according to any one of [1] to [4], wherein the antiblocking agent is fine particles composed of at least one selected from the group consisting of silicon dioxide, aluminosilicate, magnesium silicate, aluminum silicate, aluminum borate, and calcium carbonate, or fine crosslinked polymer particles composed of a styrene derivative monomer, a radical polymerizable monomer unit, and a crosslinking agent. [6] The method for producing pellets according to any one of [1] to [5], wherein the pellets contain, as an olefin-based polymer, at least one selected from the group consisting of an olefin homopolymer and an olefin-based copolymer. [7] The method for producing pellets according to any one of [1] to [6], wherein the olefin polymer is a propylene polymer containing, as a main component, a structural unit derived from propylene. [8] The method for producing pellets according to any one of [1] to [7], further comprising, before step 1, a mixing step of mixing the olefin polymer and at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier. [9] The method for producing pellets according to any one of [1] to [8], wherein step 1 further comprises weighing at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier, and supplying the weighed amount of the additive to a conveying feeder from a position separate from the olefin polymer and the antiblocking agent, and conveying the additive by the conveying feeder.

[10] A measuring and conveying device having a measuring section for measuring each of an olefin polymer and an antiblocking agent, and a conveying feeder for conveying the olefin polymer and the antiblocking agent, to which a predetermined amount of the measured olefin polymer and the antiblocking agent are supplied; a granulator which receives an olefin polymer and an antiblocking agent from a conveying feeder of the metering and conveying device, kneads the olefin polymer and the antiblocking agent while heating and melting the supplied olefin polymer to form a kneaded mixture, and discharges the kneaded mixture; Equipped with A pellet production apparatus, wherein the conveying feeder has separate supply locations for an olefin polymer and an anti-blocking agent, and the granulator has a same supply location for an olefin polymer and an anti-blocking agent. EXAMPLES

[0113] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0114] The olefin polymers prepared in the following Production Examples were measured by the following methods.

[0115] (Physical property measurement 1) [Content of structural units derived from ethylene (unit: mass%)] The value was determined by the IR spectrum measurement method described on page 256 of Polymer Analysis Handbook (published by Asakura Publishing Co., Ltd. in 1985).

[0116] [Content of structural units derived from α-olefins having 4 to 12 carbon atoms (unit: mass%)] The value was determined by the IR spectrum measurement method described on page 619 of Polymer Analysis Handbook (published by Kinokuniya Shoten in 1995).

[0117] [Melt flow rate (MFR, unit: g / 10 min)] Measurements were performed using Method A in accordance with JIS K7210-1:2014 and K7210-2:2014 at a temperature of 230°C and a load of 2.16 kg.

[0118] [Average particle size (unit: μm)] The average particle size of the olefin polymer was measured using a laser diffraction particle size distribution analyzer (HELOS / KF, sample disperser: GRADIS+VIBRI, manufactured by Sympatec). The measurement data obtained was analyzed using a dedicated analysis software (WINDOX ve5.3.1.0), and the volume-based median diameter (D50) was calculated as the average particle size.

[0119] The films obtained in the following Examples and Comparative Examples were measured by the following methods.

[0120] (Physical property measurement 2) [HAZE (unit:%)] The haze was measured according to the standard of JIS K7105. The lower the haze value, the more transparent the film is.

[0121] [Slipperiness (static friction coefficient: μs and dynamic friction coefficient: μk)] Under conditions of room temperature 23°C and humidity 50%, two films with MD 100mm x TD 75mm were stacked with their anti-chill surfaces facing each other, and a weight with a mass of 200g was placed on the surface opposite the anti-chill surface of the film with an installation area of ​​63.5mm x 63.5mm. The static friction coefficient (μs) and dynamic friction coefficient (μk) were measured by moving the weight at a moving speed of 15cm / min using an abrasion and friction tester (TOYOSEKI FRICTION TESTER TR-2 type, manufactured by Toyo Seiki Seisakusho Co., Ltd.). The slipperiness was evaluated by the values ​​of μs and μk.

[0122] [Number of fisheyes (FE)] Using a film defect inspection device (MujiKen, manufactured by NIRECO Corporation) installed on the film production machine, the number of fisheyes of 100 μm or more was counted under the following conditions.

[0123] <Measurement conditions> Camera: 1D CCD, 8,192 pixels Scan rate: Maximum approx. 0.06 msec / line (160 MHz) Resolution: 50μm / pixel

[0124] (Production Example: Production of Olefin Polymer) An olefin polymer was produced by copolymerizing ethylene, propylene, and 1-butene by gas phase polymerization using a Ziegler-Natta catalyst. The contents of each structural unit in the produced olefin polymer and the physical properties of the olefin polymer were as follows.

[0125] <Content of each structural unit in olefin polymer> Structural units derived from ethylene: 1.0% by mass Structural units derived from propylene: 95.4% by mass Structural units derived from 1-butene: 3.6% by mass

[0126] <Physical properties of olefin polymers> MFR: 7.5g / 10min Shape: powder Average particle size: 760μm

[0127] Example 1 100 parts by mass of the olefin polymer produced in the production example, 0.05 parts by mass of hydrotalcite DHT-4C (manufactured by Kyowa Chemical Industry Co., Ltd.), 0.10 parts by mass of Irganox 1010 (manufactured by BASF), and 0.10 parts by mass of Irgafos 168 (manufactured by BASF) were mixed using a Henschel mixer and fed to the feeder at 20 kg / h from a weighing section installed upstream of a conveying feeder equipped with a screw. Next, an antiblocking agent (Silysia 550, average particle size 4 μm, manufactured by Fuji Silysia Co., Ltd.) was fed at 40 g / h from a weighing section installed downstream of the conveying feeder. Then, under the conditions of a screw temperature of 30 ° C. and a screw rotation speed of 300 rpm, the mixture mixed with the Henschel mixer and the antiblocking agent were conveyed from the conveying feeder to the feed port of the following granulator. At the supply port of the granulator, an olefin polymer mixture (1) containing 0.20 parts by mass (based on 100 parts by mass of the olefin polymer) of an antiblocking agent was obtained.

[0128] The obtained antiblocking agent-containing olefin polymer (1) was melt-extruded using a 40 mm single-screw granulator (VS40-28V, manufactured by Tanabe Plastics Machinery Co., Ltd.) at a set temperature of 270°C and an extrusion rate of 10 kg / h to obtain pellets containing the olefin polymer and the antiblocking agent.

[0129] The pellets were melt extruded at a resin temperature of 250°C using a 50 mm T-die film-forming device (V-50-F600 film-molding device with a 400 mm wide T-die, manufactured by Tanabe Plastics Machinery Co., Ltd.), and then cooled and solidified while being wound up on a chill roll through which 50°C cooling water was passed, thereby obtaining a film with a thickness of 30 μm.

[0130] Example 2 The antiblocking agent was supplied to the conveying feeder at 80 g / h from a metering section installed downstream of the conveying feeder, and an olefin polymer mixture (2) containing 0.40 parts by mass of the antiblocking agent (wherein the olefin polymer is taken as 100 parts by mass) was obtained at the supply port of the granulator. A film was obtained in the same manner as in Example 1.

[0131] Example 3 100 parts by mass of the olefin polymer produced in the production example, 0.05 parts by mass of hydrotalcite DHT-4C, 0.10 parts by mass of Irganox 1010, and 0.10 parts by mass of Irgafos 168 were mixed using a Henschel mixer and fed to the feeder A at 100 kg / h from a weighing section installed upstream of the feeder A equipped with a screw. In addition, the antiblocking agent was fed to the feeder B at 0.1 kg / h from a weighing section installed upstream of the feeder B equipped with a screw, which is different from the feeder A. The mixture from the feeder A using the Henschel mixer and the antiblocking agent from the feeder B were each fed to the feed port of the following granulator.

[0132] Next, the mixture obtained by using the Henschel mixer and the antiblocking agent were melt-extruded at a set temperature of 270°C and an extrusion rate of 10 kg / h using a 47 mm twin-screw granulator (CMP-47, manufactured by Japan Steel Works, Ltd.) to obtain pellets containing an olefin polymer and an antiblocking agent.

[0133] The pellets were melt extruded at a resin temperature of 250°C using a 50 mm T-die film-forming device (V-50-F600 film-molding device with a 400 mm wide T-die, manufactured by Tanabe Plastics Machinery Co., Ltd.), and then cooled and solidified while being wound up on a chill roll through which 50°C cooling water was passed, thereby obtaining a film with a thickness of 30 μm.

[0134] Example 4 A film was obtained in the same manner as in Example 3, except that the antiblocking agent was supplied to the transport feeder B from a metering unit installed upstream of the transport feeder B at 0.2 kg / h.

[0135] Comparative Example 1 100 parts by mass of the olefin polymer produced in the production example, 0.05 parts by mass of hydrotalcite DHT-4C, 0.10 parts by mass of Irganox 1010, 0.10 parts by mass of Irgafos 168, and 0.20 parts by mass of an antiblocking agent were mixed using a Henschel mixer and fed to the feeder at 20 kg / h from a weighing unit installed upstream of a conveying feeder equipped with a screw. Then, under conditions of a screw temperature of 30° C. and a screw rotation speed of 300 rpm, the mixture mixed in the Henschel mixer was conveyed from the conveying feeder to the feeder of a 47 mm twin-screw granulator. At the feeder of the granulator, an olefin polymer mixture (3) containing 0.20 parts by mass of an antiblocking agent (wherein the olefin polymer is 100 parts by mass) was obtained.

[0136] A film was obtained in the same manner as in Example 1, except that the obtained olefin polymer mixture (3) was used.

[0137] Comparative Example 2 Except for using 0.40 parts by mass of an antiblocking agent, an olefin polymer mixture (4) containing 0.40 parts by mass of an antiblocking agent (wherein the olefin polymer is taken as 100 parts by mass) was obtained at the supply port of the granulator in the same manner as in Comparative Example 1.

[0138] A film was obtained in the same manner as in Example 1, except that the obtained olefin polymer mixture (4) was used.

[0139] Comparative Example 3 A film was obtained in the same manner as in Example 1, except that 100 parts by mass of the olefin polymer produced in the production example, 0.05 parts by mass of hydrotalcite DHT-4C, 0.10 parts by mass of Irganox 1010, 0.10 parts by mass of Irgafos 168, and 0.20 parts by mass of an antiblocking agent were mixed using a Henschel mixer and transported directly to the supply port of the granulator without using a transport feeder.

[0140] Comparative Example 4 A film was obtained in the same manner as in Comparative Example 3, except that 0.40 parts by mass of the antiblocking agent was used.

[0141] Comparative Example 5 A film was obtained in the same manner as in Example 3, except that 100 parts by mass of the olefin polymer produced in the production example, 0.05 parts by mass of hydrotalcite DHT-4C, 0.10 parts by mass of Irganox 1010, 0.10 parts by mass of Irgafos 168, and 0.10 parts by mass of an antiblocking agent were mixed using a Henschel mixer and supplied to the conveying feeder A equipped with a screw at 100 kg / h from a metering section installed upstream of the conveying feeder A, and then the mixture mixed using the Henschel mixer from the conveying feeder A was supplied to the supply port of the granulator.

[0142] Comparative Example 6 A film was obtained in the same manner as in Comparative Example 5, except that 0.20 parts by mass of the antiblocking agent was used.

[0143] The above-mentioned haze, slipperiness, and FE number were measured using the films obtained in each Example and Comparative Example. The measurement results of Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 1, and the measurement results of Examples 3 and 4 and Comparative Examples 5 and 6 are shown in Table 2, respectively.

[0144] [Table 1]

[0145] [Table 2]

[0146] As can be seen from Tables 1 and 2, the pellets produced by the pellet production methods of the respective Examples which satisfy all of the constituent requirements of the present invention can relatively reduce the occurrence of fisheyes. [Explanation of symbols]

[0147] Reference Signs List 1: Pellet manufacturing apparatus, 2: Measuring and conveying apparatus, 21: Measuring section for measuring olefin polymer, 22: Measuring section for measuring antiblocking agent, 23: Conveying feeder, 3: Granulator, 31: Supply port, 32: Cylinder, 33: Screw, 34: Discharge port

Claims

1. A method for producing pellets containing an olefin polymer and an antiblocking agent, comprising the following steps 1 and 2: Step 1: A weighing and conveying step of weighing the olefin polymer and the antiblocking agent, respectively, and supplying the weighed predetermined amounts of the olefin polymer and the antiblocking agent from separate locations to a conveying feeder and conveying them by the conveying feeder. Step 2: A granulation step in which the olefin polymer and the antiblocking agent are each supplied from the same location to a granulator from a conveying feeder, the supplied olefin polymer is heated and melted while the olefin polymer and the antiblocking agent are kneaded in the granulator to form a kneaded mixture, and the kneaded mixture is discharged from the granulator.

2. 2. The method for producing pellets according to claim 1, wherein the transport feeder is a screw-type feeder having a screw arranged along a transport direction and transporting the transported material by rotation of the screw.

3. 2. The method for producing pellets according to claim 1, wherein in step 1, the olefin polymer and the antiblocking agent are in the form of powder.

4. The method for producing pellets according to claim 1, wherein a mass ratio of the antiblocking agent is from 0.01 parts by mass to 20 parts by mass with respect to 100 parts by mass of the olefin polymer.

5. 2. The method for producing pellets according to claim 1, wherein the antiblocking agent is fine particles composed of at least one selected from the group consisting of silicon dioxide, aluminosilicate, magnesium silicate, aluminum silicate, aluminum borate, and calcium carbonate, or fine crosslinked polymer particles composed of a styrene derivative monomer, a radical polymerizable monomer unit, and a crosslinking agent.

6. 2. The method for producing pellets according to claim 1, wherein the pellets contain, as the olefin-based polymer, at least one selected from the group consisting of an olefin homopolymer and an olefin-based copolymer.

7. The method for producing pellets according to claim 1, wherein the olefin polymer is a propylene polymer containing structural units derived from propylene as a main component.

8. 2. The method for producing pellets according to claim 1, further comprising, before step 1, a mixing step of mixing the olefin polymer and at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier.

9. 2. The method for producing pellets according to claim 1, wherein the step 1 further comprises weighing at least one additive selected from the group consisting of a neutralizing agent, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a pigment, a nucleating agent, and a melt flow rate modifier, and supplying the weighed predetermined amount of the additive to a conveying feeder from a position separate from the olefin polymer and the antiblocking agent, and conveying the additive by the conveying feeder.

10. a measuring and conveying device having a measuring section for measuring each of the olefin polymer and the antiblocking agent, and a conveying feeder for conveying the olefin polymer and the antiblocking agent, to which the measured amounts of the olefin polymer and the antiblocking agent are supplied; a granulator which receives an olefin polymer and an antiblocking agent from a conveying feeder of the metering and conveying device, kneads the olefin polymer and the antiblocking agent while heating and melting the supplied olefin polymer to form a kneaded mixture, and discharges the kneaded mixture; Equipped with A pellet production apparatus, wherein the conveying feeder has separate supply locations for an olefin polymer and an anti-blocking agent, and the granulator has a same supply location for an olefin polymer and an anti-blocking agent.

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