WO2024101188A1 - Particules expansées d'extrusion de résine à base de polypropylène, leur procédé de production et corps moulé en mousse - Google Patents

Particules expansées d'extrusion de résine à base de polypropylène, leur procédé de production et corps moulé en mousse Download PDF

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WO2024101188A1
WO2024101188A1 PCT/JP2023/038889 JP2023038889W WO2024101188A1 WO 2024101188 A1 WO2024101188 A1 WO 2024101188A1 JP 2023038889 W JP2023038889 W JP 2023038889W WO 2024101188 A1 WO2024101188 A1 WO 2024101188A1
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polypropylene
polypropylene resin
resin
based resin
extruded
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PCT/JP2023/038889
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English (en)
Japanese (ja)
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清敬 中山
正樹 天野
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株式会社カネカ
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/16—Making expandable particles
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/22—After-treatment of expandable particles; Forming foamed products

Definitions

  • the present invention relates to extruded polypropylene resin foam particles, their production method, and foam molded articles.
  • Polypropylene resin foam molded products obtained using polypropylene resin foam particles are characterized by their flexibility in shape, excellent cushioning properties, light weight, and excellent heat insulation properties. These characteristics are also advantages of polypropylene resin foam molded products. Furthermore, because the base material of polypropylene resin foam molded products is polypropylene resin, they have excellent chemical resistance, heat resistance, compressive strength, and strain recovery rate after compression. Due to these advantages, polypropylene resin foam molded products are used mainly for automotive interior components and core materials for automotive bumpers, as well as for a variety of other applications such as insulation materials and cushioning packaging materials.
  • the extrusion foaming method has been used to manufacture polypropylene resin foam molded bodies, using a polypropylene resin with a branched structure as the base material.
  • polypropylene resin with a branched structure tends to be disadvantageous in terms of cost
  • a method has been proposed in which a mixture of a polypropylene resin with a branched structure and a polypropylene resin with a linear structure that does not have a branched structure is used as the base resin for extrusion foaming (see Patent Document 1).
  • the present invention was made in consideration of the above problems, and aims to provide extruded polypropylene resin foam beads with a reduced open cell ratio, and to provide a method for producing extruded foam beads that have a wide pressure range for obtaining good foamed products in the production of foamed products by molding the extruded foam beads in a mold, thereby producing extruded foam beads that have excellent moldability when producing foamed products.
  • the inventors have discovered that the above problems can be solved by using a polypropylene resin composition containing a random polypropylene resin (A) having a branched structure and a linear polypropylene resin (B) having no branched structure, both of which have similar viscosities at a specific shear rate, and have thus completed the present invention.
  • a polypropylene-based resin extruded foam bead the base resin of which contains a polypropylene-based resin composition
  • the polypropylene-based resin composition contains a random polypropylene-based resin (A) having a branched structure and a linear polypropylene-based resin (B) having no branched structure, the content of the random polypropylene-based resin (A) having a branched structure is 30% by weight or more and 80% by weight or less based on the polypropylene-based resin composition, The content of the linear polypropylene-based resin (B) is 20% by weight or more and 70% by weight or less based on the polypropylene-based resin composition,
  • the extruded polypropylene resin foam particles satisfy the following formula ( 1 ), where the complex viscosity ( ⁇ * ) at 180°C and an angular frequency ( ⁇ ) of 100 rad/sec of the random polypropylene resin (A) having a branched structure is ⁇ * (A) and the
  • the melting point of the linear polypropylene resin (B) is in the range of 130.0 to 155.0° C.
  • the random polypropylene resin (A) having a branched structure is a modified polypropylene resin obtained by melt-kneading (a) a random polypropylene resin, (b) a monomer selected from a conjugated diene and a vinyl aromatic compound, and (c) a radical polymerization initiator at a temperature at which (a) the random polypropylene resin melts and (c) the radical polymerization initiator decomposes.
  • the linear polypropylene resin (B) is a linear random polypropylene resin.
  • a polypropylene resin foamed molded article which is an in-mold molded article of the extruded foam particles according to any one of [1] to [10].
  • a method for producing extruded polypropylene resin beads comprising the steps of: The method includes: supplying a polypropylene-based resin composition to an extruder, melt-kneading the composition, adding a foaming agent, and further melt-kneading the composition to obtain a melt-kneaded product; and cooling the melt-kneaded product and extruding it through a die to foam the product.
  • the polypropylene-based resin composition contains a random polypropylene-based resin (A) having a branched structure and a linear polypropylene-based resin (B) having no branched structure, the content of the random polypropylene-based resin (A) having a branched structure is 30% by weight or more and 80% by weight or less based on the polypropylene-based resin composition, The content of the linear polypropylene-based resin (B) is 20% by weight or more and 70% by weight or less based on the polypropylene-based resin composition, Regarding the complex viscosity ( ⁇ * ) at 180° C.
  • the random polypropylene resin (A) having a branched structure is a modified polypropylene resin obtained by melt-kneading (a) a random polypropylene resin, (b) a monomer selected from a conjugated diene and a vinyl aromatic compound, and (c) a radical polymerization initiator at a temperature at which (a) the random polypropylene resin melts and (c) the radical polymerization initiator decomposes.
  • extruded polypropylene resin foamed beads of the present invention it is possible to provide extruded polypropylene resin foamed beads having a reduced open cell ratio.
  • the method for producing extruded polypropylene resin foam beads of the present invention in the production of foam molded articles by in-mold molding of the extruded foam beads, the steam pressure range for obtaining good foam molded articles is broadened, and as a result, a method can be provided for producing extruded foam beads that have excellent moldability in the production of foam molded articles.
  • the extruded polypropylene resin foam particles of the present embodiment are extruded polypropylene resin foam particles in which the base resin contains a polypropylene resin composition.
  • the polypropylene resin composition contains a random polypropylene resin (A) having a branched structure and a linear polypropylene resin (B) having no branched structure.
  • the content of the random polypropylene resin (A) having a branched structure is 30% by weight or more and 80% by weight or less based on the polypropylene resin composition.
  • the content of the linear polypropylene resin (B) is 20% by weight or more and 70% by weight or less based on the polypropylene resin composition.
  • the extruded polypropylene resin foam particles of this embodiment can provide extruded polypropylene resin foam particles with a reduced open cell rate.
  • the base resin contains a polypropylene-based resin composition described below as an essential component, and preferably contains the polypropylene-based resin composition as a main component.
  • "containing the polypropylene-based resin composition as a main component” means that the base resin contains the polypropylene-based resin composition in an amount of 90% by weight or more, preferably 95% by weight or more, more preferably 97% by weight or more, and even more preferably 99% by weight or more.
  • the polypropylene resin composition contains a random polypropylene resin (A) having a branched structure (hereinafter also referred to as “branched random polypropylene resin (A)”) and a linear polypropylene resin (B) not having a branched structure (hereinafter also referred to simply as “linear polypropylene resin (B)").
  • A random polypropylene resin
  • B linear polypropylene resin
  • the branched random polypropylene resin (A) is a modified polypropylene resin obtained by introducing a branched structure into a linear random polypropylene resin.
  • the method of introducing a branched structure into a linear random polypropylene resin is not particularly limited, but includes, for example, (a1) a method of irradiating a linear random polypropylene resin with radiation, and (a2) a method of melt-kneading a mixture containing a linear random polypropylene resin, a monomer selected from the group consisting of conjugated dienes and vinyl aromatic compounds, and a radical polymerization initiator.
  • a specific example of the method (a1) above is the method described in JP-T-2002-542360.
  • Specific examples of the above method (a2) include a method in which (a) a random polypropylene resin, (b) a monomer selected from a conjugated diene and a vinyl aromatic compound, and (c) a radical polymerization initiator are melted and kneaded at a temperature at which (a) the random polypropylene resin melts and (c) the radical polymerization initiator decomposes.
  • Random polypropylene resin refers to a random copolymer of a propylene monomer and a monomer other than propylene.
  • Random polypropylene resin contains 50 mol% or more of structural units derived from propylene monomers and less than 50 mol% of structural units derived from monomers other than propylene monomers, out of 100 mol% of all structural units contained in the resin.
  • the "structural unit derived from propylene monomer” may be referred to as a "propylene unit”.
  • the "structural unit derived from a monomer other than propylene monomer” may be referred to as a "comonomer unit”.
  • Comonomers include, for example, (a) ⁇ -olefins having 2 or 4 to 12 carbon atoms, such as ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene, and 1-decene; (b) cyclic olefins, such as cyclopentene, norbornene, and tetracyclo[6,2,11,8,13,6]-4-dodecene; and (c) 5-methylene-2 -norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6-octadiene, and other dienes; and (d) vinyl chloride, vinylidene chloride, acryl
  • Acrylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and glycidyl acrylate.
  • Methacrylic acid esters include methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and glycidyl methacrylate.
  • Styrenic monomers include styrene, methylstyrene, dimethylstyrene, alpha-methylstyrene, para-methylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, t-butylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, and trichlorostyrene.
  • the random polypropylene resin preferably has a structural unit derived from an ⁇ -olefin having 2 or 4 to 12 carbon atoms as a comonomer unit, more preferably a structural unit derived from ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene, and/or 1-decene, more preferably a structural unit derived from ethylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene, and/or 4-methyl-1-pentene, even more preferably a structural unit derived from ethylene, 1-butene, isobutene, and/or 1-pentene, and even more preferably a structural unit derived from ethylene and/or 1-butene.
  • Random polypropylene resin preferably contains 90 mol% or more of propylene units, more preferably 93 mol% or more, even more preferably 94 mol% or more, and particularly preferably 95 mol% or more, of the total 100 mol% of structural units contained in said (a) random polypropylene resin.
  • conjugated dienes include butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, and 2,5-dimethyl-2,4-hexadiene.
  • conjugated diene compounds may be used alone or in combination of two or more.
  • butadiene and isoprene are particularly preferred because (a) they are inexpensive and easy to handle, and (b) the reaction proceeds uniformly.
  • vinyl aromatic compounds include styrene; methylstyrenes such as o-methylstyrene, m-methylstyrene, p-methylstyrene, ⁇ -methylstyrene, ⁇ -methylstyrene, dimethylstyrene, and trimethylstyrene; chlorostyrenes such as ⁇ -chlorostyrene, ⁇ -chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, dichlorostyrene, and trichlorostyrene; bromostyrenes such as o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene, and tribromostyrene; fluorostyrenes such as o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, difluorostyren
  • the amount of (b) conjugated diene, etc. used is preferably 0.01 parts by weight to 5.00 parts by weight, more preferably 0.10 parts by weight to 3.00 parts by weight, and even more preferably 0.10 parts by weight to 2.00 parts by weight, per 100 parts by weight of (a) random polypropylene resin.
  • the radical polymerization initiator is an organic peroxide capable of abstracting hydrogen from (a) a random polypropylene resin and (b) a conjugated diene compound, etc.
  • Examples of the (c) radical polymerization initiator include organic peroxides such as ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, and peroxyesters.
  • organic peroxides those with particularly high hydrogen abstraction ability are preferred.
  • organic peroxides with high hydrogen abstraction ability include peroxyketals such as 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, n-butyl 4,4-bis(t-butylperoxy)valerate, and 2,2-bis(t-butylperoxy)butane; dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, ⁇ , ⁇ '-bis(t-butylperoxy-m-isopropyl)benzene, t-butylcumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5- Suitable examples of the organic peroxides include dialkyl peroxides such as di(t-butylperoxy)-3-hexyn
  • the amount of (c) radical polymerization initiator used is preferably 0.01 parts by weight to 5.00 parts by weight, more preferably 0.10 parts by weight to 3.00 parts by weight, even more preferably 0.10 parts by weight to 2.00 parts by weight, and particularly preferably 0.10 parts by weight to 1.50 parts by weight, relative to 100 parts by weight of (a) random polypropylene resin.
  • examples of the apparatus for melt-kneading (a) random polypropylene resin, (b) monomer such as conjugated diene, and (c) radical polymerization initiator include kneaders such as rolls, co-kneaders, Banbury mixers, Brabenders, single-screw extruders, and twin-screw extruders; horizontal mixers such as twin-screw surface renewal machines and twin-screw multi-disk devices; and vertical mixers such as double helical ribbon mixers. Of these, it is preferable to use a kneader, and in particular extruders such as single-screw extruders and twin-screw extruders are preferable from the viewpoint of productivity.
  • the complex viscosity ( ⁇ * ) of the branched random polypropylene resin (A) is not particularly limited, but when the complex viscosity at an angular frequency ( ⁇ ) of 100 rad/sec is " ⁇ * 100", the ⁇ * 100 of the branched random polypropylene resin (A) is preferably 100 Pa ⁇ sec to 1000 Pa ⁇ sec, more preferably 150 Pa ⁇ sec to 700 Pa ⁇ sec, and even more preferably 200 Pa ⁇ sec to 500 Pa ⁇ sec.
  • ⁇ * 100 of the branched random polypropylene resin (A) may be referred to as " ⁇ * (A)".
  • the melting point (Tm) of the branched random polypropylene resin (A) is not particularly limited, but is preferably from 130.0°C to 155.0°C, and more preferably from 135.0°C to 155.0°C. In this specification, the melting point is a value determined by measurement using differential scanning calorimetry.
  • the cold crystallization temperature (Tc) of the branched random polypropylene resin (A) is not particularly limited, but is preferably from 90.0°C to 120.0°C, and more preferably from 100.0°C to 120.0°C.
  • the cold crystallization temperature is a value determined by measurement using differential scanning calorimetry.
  • the melt flow rate (MFR) of the branched random polypropylene resin (A) is not particularly limited, but is preferably 0.5 g/10 min or more and 50 g/10 min or less, more preferably 0.5 g/10 min or more and 30 g/10 min or less, and even more preferably 1 g/10 min or more and 10 g/10 min or less.
  • MFR is a value determined by measurement at a temperature of 230° C. in accordance with ISO 1133.
  • the linear polypropylene resin (B) is a linear resin that contains 50 mol% or more of structural units derived from propylene monomers in 100 mol% of all structural units contained in the resin and does not have a branched structure.
  • Examples of the linear polypropylene resin (B) include propylene homopolymer, block polypropylene resin, and random polypropylene resin, and propylene homopolymer and random polypropylene resin are preferable, and random polypropylene resin is more preferable.
  • the random polypropylene resin is the same as the embodiment described in the above-mentioned [(a) Random polypropylene resin].
  • the complex viscosity ( ⁇ * ) of the linear polypropylene resin (B) is not particularly limited, but when the complex viscosity at an angular frequency ( ⁇ ) of 100 rad/sec is " ⁇ * 100", the ⁇ * 100 of the linear polypropylene resin (B) is preferably 100 Pa ⁇ sec to 1500 Pa ⁇ sec, more preferably 150 Pa ⁇ sec to 800 Pa ⁇ sec, even more preferably 150 Pa ⁇ sec to 500 Pa ⁇ sec, even more preferably 150 Pa ⁇ sec to 450 Pa ⁇ sec, and particularly preferably 150 Pa ⁇ sec to 400 Pa ⁇ sec.
  • ⁇ * 100 of the linear polypropylene resin (B) may be referred to as " ⁇ * (B)".
  • the melting point (Tm) of the linear polypropylene resin (B) is not particularly limited, but is preferably 130.0°C to 155.0°C, and more preferably 135.0°C to 155.0°C.
  • the cold crystallization temperature (Tc) of the linear polypropylene resin (B) is not particularly limited, but is preferably 80.0°C to 130.0°C, and more preferably 85.0°C to 110°C.
  • the melt flow rate (MFR) of the linear polypropylene resin (B) is not particularly limited, but is preferably 10 g/10 min or more and 1000 g/10 min or less, more preferably 10 g/10 min or more and 100 g/10 min or less, even more preferably 15 g/10 min or more and 80 g/10 min or less, and particularly preferably 20 g/10 min or more and 70 g/10 min or less.
  • the content of the branched random polypropylene resin (A) and the content of the linear polypropylene resin (B) are, relative to the polypropylene resin composition, 30% by weight to 80% by weight and 20% by weight to 70% by weight, preferably 40% by weight to 80% by weight and 20% by weight to 60% by weight, and more preferably 50% by weight to 80% by weight and 20% by weight to 50% by weight.
  • the complex viscosity ( ⁇ * ) at 180° C. and an angular frequency ( ⁇ ) of 100 rad/sec is expressed by the following (Formula 1), where the ⁇ * of the branched random polypropylene resin (A) is ⁇ * (A) and the ⁇ * of the linear polypropylene resin (B) is ⁇ * (B): 0.2 ⁇ * (B)/ ⁇ * (A) ⁇ 1.5 (Equation 1) and satisfies the following (Equation 2): 0.4 ⁇ * (B)/ ⁇ * (A) ⁇ 1.5 (Equation 2) It is preferable that the following formula (3): 0.5 ⁇ * (B)/ ⁇ * (A) ⁇ 1.5 (Equation 3) It is more preferable that the following formula (Formula 4): 0.6 ⁇ * (B)/ ⁇ * (A) ⁇ 1.4 (Equation 4) It is even more preferable that
  • the complex viscosity at 180°C and an angular frequency of 100 rad/sec corresponds to the viscosity at a high shear rate, which is relatively close to that during melt kneading.
  • any of the above formulas (1) to (4) is satisfied for such a specific complex viscosity, it means that the viscosities at a high shear rate of the branched random polypropylene resin (A) and the linear polypropylene resin (B) are close to each other.
  • the polypropylene resin composition may contain components other than the branched random polypropylene resin (A) and the linear polypropylene resin (B) described above (hereinafter, also referred to as "other components"), as long as the effects of the present invention are not impaired.
  • the other components include resins or rubbers other than the resin (A) and the resin (B) (hereinafter, also referred to as "other resins, etc.”), foam nucleating agents, (a) stabilizers such as antioxidants, metal deactivators, phosphorus-based processing stabilizers, ultraviolet absorbers, ultraviolet stabilizers, fluorescent brighteners, metal soaps, and antacid adsorbents, and/or (b) additives such as crosslinkers, chain transfer agents, lubricants, plasticizers, fillers, reinforcing materials, flame retardants, colorants, and antistatic agents. These other components may be used alone or in combination of two or more.
  • the total content of the other components in the polypropylene resin composition is not particularly limited.
  • the total content of the other components in the polypropylene resin composition is, for example, preferably 0.01 to 50.00 parts by weight, and more preferably 0.05 to 30.00 parts by weight, per 100 parts by weight of the polypropylene resin composition.
  • the other resins include (a) ethylene-based resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear very low-density polyethylene, ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, and ethylene/methacrylic acid copolymer, and (c) styrene-based resins such as polystyrene, styrene/maleic anhydride copolymer, and styrene/ethylene copolymer.
  • ethylene-based resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear very low-density polyethylene, ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, and ethylene/methacrylic acid copolymer
  • the rubber examples include olefin-based rubbers such as ethylene/propylene rubber, ethylene/butene rubber, ethylene/hexene rubber, and ethylene/octene rubber.
  • the total content of the other resins and rubbers in the base resin is not particularly limited.
  • the total content of the other resins and rubbers in the polypropylene-based resin composition is, for example, preferably 1 to 30 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the polypropylene-based resin composition.
  • bubble nucleating agent examples include a mixture of sodium bicarbonate and citric acid, monosodium citrate, talc, calcium carbonate, etc. These bubble nucleating agents may be used alone or in combination of two or more.
  • the content of the bubble nucleating agent in the polypropylene resin composition is not particularly limited.
  • the content of the bubble nucleating agent is preferably 0.01 to 5.00 parts by weight, more preferably 0.01 to 3.50 parts by weight, even more preferably 0.01 to 1.00 parts by weight, and particularly preferably 0.01 to 0.50 parts by weight, per 100 parts by weight of the polypropylene resin composition.
  • This configuration has the advantage that the average bubble diameter and bubble shape of the extruded foamed particles become uniform, and as a result, the foamability during extrusion foaming tends to be stable.
  • the bulk density of the extruded foam particles is not particularly limited, but is preferably 45 g/L to 300 g/L, more preferably 50 g/L to 250 g/L, even more preferably 55 g/L to 230 g/L, and particularly preferably 60 g/L to 220 g/L.
  • the above-mentioned configuration has the advantage that the polypropylene resin in-mold foamed article obtained by using the extruded foam particles exhibits characteristics such as the freedom of shape, cushioning properties, light weight, and heat insulation properties.
  • the average cell diameter (also referred to as the average bubble diameter) of the extruded polypropylene resin foam particles is not particularly limited, but is preferably 100 ⁇ m or more and 500 ⁇ m or less, and more preferably 120 ⁇ m or more and 400 ⁇ m or less. If the average bubble diameter of the extruded polypropylene resin foam particles is 100 ⁇ m or more, the shrinkage of the foamed molded product tends to be small, and if it is 500 ⁇ m or less, the molding cycle during in-mold foam molding tends to be shortened.
  • the open cell ratio of the extruded polypropylene resin foam particles is preferably as low as possible.
  • the open cell ratio of the extruded polypropylene resin foam particles is preferably 15.0% or less, more preferably 12.0% or less, more preferably 8.0% or less, more preferably 7.0% or less, even more preferably 6.0% or less, and particularly preferably 5.0% or less.
  • the lower limit of the open cell ratio of the extruded polypropylene resin foam particles is not particularly limited, and is, for example, 0.0% or more.
  • the extruded polypropylene resin foam particles have an advantage that the extruded polypropylene resin foam particles have excellent moldability because the cells are hardly broken and shrunk during molding, and (b) the extruded polypropylene resin foam particles have an advantage that the extruded polypropylene resin foam particles have characteristics such as shape arbitrariness, cushioning properties, light weight, compressive strength and heat insulation properties.
  • the open cell ratio of the extruded polypropylene resin foam particles is a value obtained by measuring using an air-comparison type pycnometer [Model 1000, manufactured by Tokyo Science Co., Ltd.] according to the method described in Procedure C of ASTM D2856-87.
  • the method of measuring the volume Va is also called the submersion method.
  • the method for producing extruded polypropylene resin foam beads of the present embodiment is as follows: The method includes: supplying a polypropylene-based resin composition to an extruder, melt-kneading the composition, adding a foaming agent, and further melt-kneading the composition to obtain a melt-kneaded product; and cooling the melt-kneaded product and extruding it through a die to foam the product.
  • the polypropylene-based resin composition contains a random polypropylene-based resin (A) having a branched structure and a linear polypropylene-based resin (B) having no branched structure, the content of the random polypropylene-based resin (A) having a branched structure is 30% by weight or more and 80% by weight or less based on the polypropylene-based resin composition, The content of the linear polypropylene-based resin (B) is 20% by weight or more and 70% by weight or less based on the polypropylene-based resin composition, Regarding the complex viscosity ( ⁇ * ) at 180° C.
  • the method for producing extruded polypropylene resin foam beads of this embodiment broadens the pressure range required to obtain a good foam molded product in the production of a foam molded product by molding the extruded foam beads in a mold, and as a result, a method can be provided for producing extruded foam beads that have excellent moldability when producing a foam molded product.
  • the foaming agent used in the manufacturing method of the present embodiment is not particularly limited as long as it is a foaming agent generally used in extrusion foaming.
  • the foaming agent include (a) (a-1) aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, and hexane; (a-2) alicyclic hydrocarbons such as cyclopentane and cyclobutane; (a-3) ethers such as dimethyl ether, diethyl ether, and methyl ethyl ether; (a-4) alcohols such as methanol and ethanol; (a-5) inorganic gases such as air, nitrogen, and carbon dioxide; and (a-6) physical foaming agents such as water, and (b) chemical foaming agents including thermal decomposition type foaming agents such as sodium bicarbonate, azodicarbonamide, and dinitrosopentamethylenetetramine.
  • inorganic gases such as sodium bicarbonate,
  • the amount of the foaming agent used is preferably 0.5 parts by weight to 7.0 parts by weight, more preferably 0.5 parts by weight to 6.0 parts by weight, even more preferably 0.5 parts by weight to 5.0 parts by weight, even more preferably 0.5 parts by weight to 4.0 parts by weight, and particularly preferably 0.5 parts by weight to 3.0 parts by weight, per 100.0 parts by weight of the polypropylene resin composition.
  • the extruder used to obtain the melt-kneaded product may be, for example, a single-screw extruder or a twin-screw extruder. Of these, a twin-screw extruder is preferred because of its excellent melt-kneading properties.
  • the cylinder temperature of the extruder is not particularly limited and can be set appropriately depending on the melting point of the polypropylene resin composition used, the type and amount of the foaming agent used, etc., from the viewpoint of sufficiently melt-kneading the polypropylene resin composition and the foaming agent.
  • the cylinder temperature of the extruder is preferably 150°C or higher and 250°C or lower, and more preferably 170°C or higher and 230°C or lower.
  • the cooling device used to cool the obtained molten kneaded product examples include a single screw extruder, a static mixer, and a melt cooler.
  • a die for extruding the cooled molten kneaded product is provided at the tip of the extrusion direction of the molten kneaded product.
  • the temperature of the cooling device is not particularly limited as long as it is a temperature suitable for foaming the obtained molten kneaded product.
  • the temperature of the cooling device is preferably 120°C or more and 180°C or less, more preferably 130°C or more and 170°C or less.
  • the cooled molten mixture is extruded through holes provided in the die into a region where the pressure is lower than the internal pressure of the cooling device (hereinafter, also referred to as the "low pressure region").
  • the molten mixture may be extruded into a gas phase or into a liquid phase.
  • the pressure of the low pressure region is not particularly limited, but is preferably 5 MPa or less, and more preferably 1 MPa or less.
  • the extruded molten mixture immediately begins to foam, and when foaming is completed, a polypropylene resin extruded foam is obtained.
  • the foaming process may further include a chopping process for cutting the extruded molten kneaded material into particles.
  • the molten kneaded material (extruded foam) may be chopped during foaming, or the molten kneaded material (extruded foam) may be chopped after foaming has been completed.
  • the method for chopping the extruded molten kneaded material is not particularly limited.
  • the molten kneaded material may be chopped with a cutter or the like provided next to the die along the extrusion direction.
  • the low pressure region may be in either a gas or liquid phase, but is preferably filled with water.
  • the low pressure region preferably further includes a water circulation path connected to a water pipe for discharging the resulting extruded foam particles and a water pipe for returning the water after discharging the extruded foam particles to the low pressure region.
  • the extruder is connected to the cooling device with a die at the tip in the extrusion direction, and the cooled molten mixture is extruded from the die and expanded in a low pressure region.
  • the polypropylene resin foam molded article of this embodiment is an in-mold molded article of the extruded polypropylene resin foam beads described above.
  • the polypropylene resin foam molded article can be obtained by filling the extruded foam beads into a mold that can be closed but cannot be sealed, and then heating and molding with steam or the like.
  • Examples of methods for producing the foam molded article include (a) a method in which the foam beads are pressurized with an inorganic gas to impregnate the particles with the inorganic gas and impart a predetermined particle internal pressure, and then the particles are filled into a mold and heat-fused with steam or the like (e.g., JP-B-51-22951), (b) a method in which the foam beads are compressed with gas pressure, filled into a mold, and heat-fused with steam or the like by utilizing the recovery force of the particles (e.g., JP-B-53-33996), and (c) a method in which the foam beads are filled into a mold with an expanded gap, the mold is closed to a predetermined gap, the filled foam beads are compressed, and then heat-fused with steam or the like.
  • a method in which the foam beads are pressurized with an inorganic gas to impregnate the particles with the inorganic gas and impart a predetermined particle internal pressure, and then the particles are filled into
  • the pressure range of steam or the like required to obtain a good foamed molded article is wide. That is, the molding range of the extruded foamed beads is wide.
  • the molding width of the extruded foam particles refers to the range of vapor pressure (gauge pressure) during in-mold foam molding that can obtain a foam molded product that satisfies the following when the extruded foam particles are foam molded in-mold: (x1) the extruded foam particles are sufficiently fused to each other, (x2) the gaps between the extruded foam particles are sufficiently filled, (x3) the surface is beautiful, (x4) the surface is not melted, and (x5) there is no shrinkage and the shape of the mold (metal mold) used in the in-mold foam molding is transferred.
  • Polypropylene resin foam molded products are used for automobile interior components, core materials for automobile bumpers, insulation materials, cushioning packaging materials, etc.
  • isoprene manufactured by Kuraray Co., Ltd., isoprene monomer
  • isoprene monomer which is a conjugated diene compound
  • the amount of the resin mixture fed to the twin-screw extruder was 70 kg/h.
  • the amount of the resin mixture fed means the amount of the resin mixture per unit time prepared in the twin-screw extruder at the time when the conjugated diene compound was fed to the twin-screw extruder.
  • the prepared resin mixture was melt-kneaded in a twin-screw extruder at a cylinder temperature of 200° C. and a screw rotation speed of 230 rpm to obtain Resin A-1 as a branched random polypropylene resin.
  • the obtained Resin A-1 was discharged in a strand shape from a die at a discharge rate of 70 kg/h.
  • the discharged strand was (a) water-cooled, and then (b) chopped into pellets (cylindrical).
  • Resin A-2 was obtained in the same manner as in the production example of Resin A-1, except that J2021GR (manufactured by Prime Polymer Co., Ltd., linear random polypropylene resin, melting point: 156°C, MFR: 25g/10min) was used instead of RD265CF as the raw material resin, and the amount of isoprene supplied was changed from 0.41 parts by weight to 0.47 parts by weight.
  • J2021GR manufactured by Prime Polymer Co., Ltd., linear random polypropylene resin, melting point: 156°C, MFR: 25g/10min
  • Resins B-1 to B-5 were used as linear polypropylene resins.
  • Resins B-1 and B-2 are resins that correspond to the linear polypropylene resin (B) in this embodiment, and resins B-3 to B-5 are comparative resins that do not correspond to the linear polypropylene resin (B) in terms of complex viscosity.
  • Resin B-1 Linear random polypropylene resin manufactured by Prime Polymer Co., Ltd. (F329RA, melting point 137°C, MFR: 27g/10min)
  • Resin B-2 Linear random polypropylene resin manufactured by Prime Polymer Co., Ltd.
  • Resin B-3 Linear random polypropylene resin manufactured by Prime Polymer Co., Ltd. (F724NPC, melting point 150°C, MFR: 7g/10min)
  • Resin B-4 Linear random polypropylene resin manufactured by Prime Polymer Co., Ltd. (E330GV, melting point 143°C, MFR: 2g/10min)
  • Resin B-5 Linear random polypropylene resin manufactured by Prime Polymer Co., Ltd. (B221WC, melting point 149°C, MFR: 0.5g/10min)
  • C-1 was used as a bubble nucleating agent.
  • C-1 Talc manufactured by Hayashi Kasei Co., Ltd. (Talc Powder PK-S)
  • the low-pressure region is equipped with a water circulation path connected to a water pipe for discharging the obtained extruded foamed particles and a water pipe for returning the water after discharging the extruded foamed particles to the low-pressure region.
  • the obtained extruded foamed particles were measured for bulk density, average cell diameter, and open cell ratio, and the results are shown in Tables 2 to 3.
  • a polypropylene resin foam molded article was produced by the following method.
  • a block-shaped mold (molding space: 381 mm long x 320 mm wide x variable thickness) was set in a state where the thickness of the molding space was 78 mm (cracking rate: 30%).
  • the molding space of the mold was filled with polypropylene resin extrusion foam particles. Thereafter, the mold was moved so that the thickness of the molding space in the mold was 60 mm, and the molding space was compressed.
  • the air in the mold was expelled with steam of 0.10 MPa (gauge pressure), and then, the molded article was heated and molded for 10 seconds using steam showing a steam pressure of 0.20 to 0.30 MPa (gauge pressure), to obtain a foam molded article.
  • the obtained polypropylene resin foam molded article was dried at 75°C for 16 hours or more, and left to stand at 23°C for 24 hours or more, and various evaluations were performed.
  • the steam pressure used for molding was changed every 0.02 MPa, and the steam pressure at which a good foam molded article was obtained is shown in Tables 2 to 3.
  • the certain time is 120 seconds when the melt flow rate is more than 0.5 g / 10 minutes and 1.0 g / 10 minutes or less; 60 seconds when the melt flow rate is more than 1.0 g / 10 minutes and 3.5 g / 10 minutes or less; and 30 seconds when the melt flow rate is more than 3.5 g / 10 minutes and 10 g / 10 minutes or less.
  • the temperature at the peak of the DSC curve of the sample obtained during cooling was taken as the cold crystallization temperature Tc.
  • the temperature of the peak (melting peak) of the DSC curve of the sample obtained during the second heating was taken as the melting point Tm.
  • a viscoelasticity measuring device (MCR102 manufactured by Anton Paar) equipped with a parallel plate type measuring jig of 25 mm ⁇ was used as the parallel plate type viscoelasticity measuring device. Dynamic viscoelasticity measurements were performed under the following conditions of 180° C., strain 5%, and angular frequencies of 0.1 to 100 rad/sec according to the following procedure. (1) A resin sample was press-molded at 190° C. into a plate shape of about 1.5 mm, and then a measurement sample having a diameter of about 25 mm was cut out from the plate. (2) A resin sample was sandwiched between two parallel plates heated to the measurement temperature, and after melting, the gap distance between the plates was set to 1.0 mm.
  • the bulk density of the extruded foam particles was calculated by carrying out the following steps (1) to (3) in that order.
  • (1) The extruded polypropylene resin particles are poured into a measuring cup of about 1 L, the internal volume of which Vk (L) has been accurately measured in advance, until the measuring cup overflows.
  • (2) The powder surface (upper end) of the container is scraped off, and the weight Wb (g) of the extruded polypropylene resin particles in the container is measured.
  • Average cell diameter Ten pieces were randomly taken from the extruded foamed beads and cut with great care so as not to destroy the cell membrane. The cut surface of each sample was observed under a microscope (VHX digital microscope, manufactured by Keyence Corporation). A line equivalent to a length of 1 mm was drawn on the part excluding the surface layer, and the number of cells through which the outer line passed was counted. Thereafter, the average cell diameter was measured in accordance with ASTM D3576.
  • the ratio (%) of the number of extruded foam particles that were broken within the extruded foam particles at the fracture surface to the total number of extruded foam particles present at the fracture surface was calculated, and samples with this ratio of 60% or more were deemed to have passed, and samples with this ratio of less than 60% were deemed to have failed.
  • the extruded foam particles were visually observed between the extruded foam particles in an area of 100 mm x 100 mm near the center of both sides (surfaces perpendicular to the thickness direction) of the surface of the polypropylene resin foam molded article, and the number of gaps between the extruded foam particles (recessed areas relative to the surface) was counted. A sample having 20 or less gaps between the extruded foam particles was rated as pass, and a sample having 21 or more gaps was rated as fail.
  • the surface melt state of the polypropylene resin foam molded article was evaluated immediately after molding, without drying or leaving the obtained polypropylene resin foam molded article to stand. Specifically, in the case of a polypropylene-based resin foam molded article immediately after molding, (a) the foam molded article stuck to the mold and could not be released, or (b) even if the foam molded article could be released from the mold, a part of the foam molded article surface, such as a steam slit portion on the foam molded article surface, remained on the mold side, the article was deemed to have failed; otherwise, the article was deemed to have passed.
  • the length, width and thickness of the polypropylene resin foam molded article were measured. Using the obtained results, the shrinkage rate (%) of each of the length, width and thickness of the polypropylene resin foam molded article was evaluated according to the following formula: ⁇ (dimension of molding space in mold) - (dimension of molded product) ⁇ x 100 / dimension of molding space in mold A sample was deemed to pass if the shrinkage rates of the length, width and thickness were all 5% or less, and was deemed to fail if any one of them was greater than 5%. The dimensions of the molding space in the mold were 381 mm length, 320 mm width and 60 mm thickness.
  • the open cell ratio of the obtained extruded foamed beads was as high as 21% at the minimum in Comparative Examples 1 to 5, whereas it was only 8% at the maximum in Examples 1 to 9. From Tables 2 and 3, it is understood that, regarding the moldable width of the extruded foamed beads, in Comparative Examples 1 to 5, even if molding was possible, it was zero, whereas in Examples 1 to 9, there was a width of 0.04 MPa.

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Abstract

L'invention concerne des particules expansées d'extrusion de résine à base de polypropylène présentant un faible taux d'alvéoles ouverts. Lorsqu'un corps moulé en mousse est fabriqué par moulage dans le moule desdites particules, la plage de pression pour obtenir un excellent corps moulé en mousse devient large. Par conséquent, l'invention concerne également un procédé de production de particules expansées d'extrusion présentant une excellente aptitude au moulage lors de la fabrication d'un corps moulé en mousse.　La particule expansée d'extrusion de résine à base de polypropylène selon la présente invention contient, dans une résine de matériau de base, une composition de résine à base de polypropylène. La composition de résine contient une résine à base de polypropylène aléatoire (A) ayant une structure ramifiée et une résine à base de polypropylène linéaire (B) n'ayant pas de structure ramifiée. En ce qui concerne la viscosité complexe (η*) à 180 °C et à une fréquence angulaire (ω) de 100 rad/sec, lorsque η* de la résine à base de polypropylène aléatoire (A) est désigné par η*(A) et η* de la résine à base de polypropylène linéaire (B) est désigné par η*(B) (B), la formule 1 est satisfaite.　Formule 1 : 0,2 < η* (B)/η*(A) < 1,5
PCT/JP2023/038889 2022-11-10 2023-10-27 Particules expansées d'extrusion de résine à base de polypropylène, leur procédé de production et corps moulé en mousse WO2024101188A1 (fr)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09249763A (ja) * 1996-03-15 1997-09-22 Sekisui Plastics Co Ltd ポリプロピレン系樹脂発泡粒子
JP2012102188A (ja) * 2010-11-08 2012-05-31 Japan Polypropylene Corp 発泡シート成形用ポリプロピレン系樹脂組成物および発泡シート
JP2013231099A (ja) * 2012-04-27 2013-11-14 Mitsui Chemicals Inc プロピレン系重合体、プロピレン系重合体組成物、予備発泡粒子発泡成形体、射出発泡成形体およびそれらの製造方法
WO2022154070A1 (fr) * 2021-01-15 2022-07-21 株式会社カネカ Particules de mousse extrudée de résine de polypropylène, leur procédé de production et corps moulé en mousse
WO2022191181A1 (fr) * 2021-03-10 2022-09-15 株式会社カネカ Composition de résine de polypropylène destinée au soufflage par extrusion, particules soufflées par extrusion, et mousse moulée
WO2022203036A1 (fr) * 2021-03-25 2022-09-29 株式会社カネカ Particules de mousse extrudée de résine de polypropylène, leur procédé de production et corps moulé en mousse
JP2022152955A (ja) * 2021-03-29 2022-10-12 株式会社カネカ ポリプロピレン系樹脂押出発泡粒子の製造方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09249763A (ja) * 1996-03-15 1997-09-22 Sekisui Plastics Co Ltd ポリプロピレン系樹脂発泡粒子
JP2012102188A (ja) * 2010-11-08 2012-05-31 Japan Polypropylene Corp 発泡シート成形用ポリプロピレン系樹脂組成物および発泡シート
JP2013231099A (ja) * 2012-04-27 2013-11-14 Mitsui Chemicals Inc プロピレン系重合体、プロピレン系重合体組成物、予備発泡粒子発泡成形体、射出発泡成形体およびそれらの製造方法
WO2022154070A1 (fr) * 2021-01-15 2022-07-21 株式会社カネカ Particules de mousse extrudée de résine de polypropylène, leur procédé de production et corps moulé en mousse
WO2022191181A1 (fr) * 2021-03-10 2022-09-15 株式会社カネカ Composition de résine de polypropylène destinée au soufflage par extrusion, particules soufflées par extrusion, et mousse moulée
WO2022203036A1 (fr) * 2021-03-25 2022-09-29 株式会社カネカ Particules de mousse extrudée de résine de polypropylène, leur procédé de production et corps moulé en mousse
JP2022152955A (ja) * 2021-03-29 2022-10-12 株式会社カネカ ポリプロピレン系樹脂押出発泡粒子の製造方法

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