Classifications

• • 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
  • C08J9/228—Forming foamed products
  • C08J9/232—Forming foamed products by sintering expandable particles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
  • C08F255/02—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00 on to polymers of olefins having two or three carbon atoms
• • 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
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/06—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• • 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
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/03—Extrusion of the foamable blend
• • 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
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/034—Post-expanding of foam beads or sheets
• • 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
  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/06—CO2, N2 or noble gases
• • 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
  • C08J2205/00—Foams characterised by their properties
  • C08J2205/04—Foams characterised by their properties characterised by the foam pores
  • C08J2205/052—Closed cells, i.e. more than 50% of the pores are closed
• • 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
  • C08J2351/00—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers
  • C08J2351/06—Characterised by the use of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
• • 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
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases

Definitions

• the present invention relates to a polypropylene-based resin composition that can be suitably used for extrusion foaming, a method for producing the same, a method for producing polypropylene-based resin pre-foamed particles, and a method for producing a polypropylene-based resin foam molded article.
• the foamed molded product obtained by using the polypropylene-based resin pre-foamed particles has features such as arbitrary shape, cushioning property, light weight, and heat insulating property. Further, since the base material of the foam molded product is made of polypropylene resin, it is excellent in chemical resistance, heat resistance, compressive strength, and strain recovery rate after compression. Due to these characteristics, the foam molded product obtained by using the polypropylene-based resin pre-foamed particles is used in various applications such as an automobile interior member, a core material for an automobile bumper, a heat insulating material, and a buffer packaging material.
• the polypropylene-based resin pre-foamed particles used to obtain a polypropylene-based resin foam molded product generally have polypropylene-based resin particles dispersed in water together with a volatile foaming agent in a pressure-resistant container, and the melting point of the polypropylene-based resin.
• the polypropylene-based resin particles are heated to a nearby temperature to impregnate the polypropylene-based resin particles with a foaming agent, and the polypropylene-based resin particles are kept constant at a temperature and pressure inside the container under pressure equal to or higher than the vapor pressure indicated by the foaming agent.
• the polypropylene-based resin pre-foamed particles obtained by the decompression foaming method can be easily secondary molded by in-mold molding using heated steam to obtain a foamed molded product, which is useful foaming having the above-mentioned characteristics. A molded product can be obtained.
• the pre-foaming process is performed by an extruder to make the size suitable for foaming, and then to the foaming process in a pressure-resistant container.
• Patent Document 1 it is obtained by melt-kneading a polypropylene-based resin with an aromatic vinyl monomer and / or an isoprene monomer and a radical generator, and has stretch viscosity characteristics showing that it has high melt elasticity.
• a method of obtaining foamed particles by performing extrusion foaming using the applied modified polypropylene resin has been proposed.
• Patent Document 2 uses a random polypropylene-based resin having a low melting point as a main component of a base material as pre-foamed particles having excellent secondary moldability obtained by an extrusion foaming method, and propylene alone as a part of the base material. Those using a polymer have been proposed.
• Patent Document 3 by using a polypropylene resin having a specific viscoelastic property as a base material, prefoamed particles having a low internal foaming ratio and excellent secondary moldability obtained by an extrusion foaming method can be obtained. Proposed.
• Patent Document 4 describes pre-foamed particles based on a propylene homopolymer having specific viscoelastic properties, and steam at 165 ° C.
• Patent Document 5 describes prefoamed particles based on a propylene homopolymer having a specific melt tension and a linear molecular structure, and water vapor used for secondary molding of the prefoamed particles. Is stated to be 4.5 kg / cm 2 (0.45 MPa).
• Patent Document 6 a resin composition composed of a propylene-olefin copolymer having a specific intrinsic viscosity and an ethylene homopolymer or an ethylene-olefin copolymer having a specific intrinsic viscosity is used as a base resin. It is described that the pre-foamed particles obtained by the extrusion foaming method and the pre-foamed particles are secondarily molded with steam at 145 ° C. (corresponding to about 0.41 MPa).
• Patent Document 1 Although foamed particles having a low density and a high closed cell ratio can be obtained, there is a problem that they are not necessarily excellent in secondary moldability.
• Patent Document 2 has a problem that the strength of the obtained foamed molded product is not sufficient as a result of using a random polypropylene-based resin having a low melting point as a main component of the base material.
• Patent Document 3 also has a problem that the strength of the obtained foamed molded product is not sufficient because random polypropylene is used as the base material.
• Patent Documents 4 to 6 when the prefoamed particles are to be secondarily molded by using heated steam, there is a problem that higher temperature and higher pressure steam is required and the utility cost is significantly increased.
• the present invention uses polypropylene-based resin pre-foamed particles as a base material when produced by extrusion foaming, so that the foamed particles have a high closed cell ratio and are good secondary.
• a system resin composition a method for producing the same, a method for producing polypropylene-based resin pre-foamed particles, and a method for producing a polypropylene-based resin foam molded product.
• the present invention relates to a polypropylene-based resin composition, which satisfies the following requirements (1) to (4) in one or more embodiments.
• the melting tension at 230 ° C. is 2.94 cN or more and 19.6 cN or less.
• the melting point Tm measured by differential scanning calorimetry is more than 150 ° C and less than 159 ° C.
• the cold crystallization temperature Tc measured by differential scanning calorimetry is 122 ° C or higher and lower than 130 ° C.
• the heat of fusion ⁇ H measured by differential scanning calorimetry is 85 J / g or more and less than 100 J / g.
• the present invention is, in one or more embodiments, a method for producing the polypropylene-based resin composition, wherein one or more monomers selected from the group consisting of polypropylene-based resins, conjugated diene compounds, and aromatic vinyl compounds.
• the present invention relates to a method for producing a polypropylene-based resin composition, which comprises a step of melt-kneading and extruding the radical polymerization initiator at a temperature at which the polypropylene-based resin is melted and the radical polymerization initiator is decomposed.
• the present invention is a method for producing polypropylene-based resin pre-foamed particles according to one or more embodiments, which comprises a step of extruding and foaming the polypropylene-based resin composition to obtain polypropylene-based resin pre-foamed particles.
• the present invention relates to a method for producing foamed particles.
• the present invention is a method for producing a polypropylene-based resin foam-molded article according to one or more embodiments, wherein the polypropylene-based resin pre-foamed particles obtained by the above-mentioned method for producing polypropylene-based resin pre-foamed particles are steam-molded.
• the present invention relates to a method for producing a polypropylene-based resin foam molded product to obtain a foamed molded product.
• the pre-foamed particles obtained by using the polypropylene-based resin pre-foamed particles as a base material when produced by extrusion foaming have a high closed cell ratio.
• a foam molded article having a high closed cell ratio, good secondary moldability, and low vapor pressure can be obtained.
• a polypropylene-based resin composition that can be used as a base material when the pre-foamed particles are produced by extrusion foaming can be obtained.
• a foamed molded article having a high closed cell ratio, good secondary moldability, and low vapor pressure can be obtained.
• Pre-foamed particles can be obtained.
• a high-strength foam molded product can be molded with a low vapor pressure.
• melt tension at 230 ° C. (hereinafter, also simply referred to as "melt tension") of 2.94 cN or more and 19.6 cN or less, and (2) difference.
• Melting point Tm measured by scanning calorific value analysis exceeds 150 ° C. and less than 159 ° C.
• Cold crystallization temperature Tc measured by differential scanning calorific value analysis is 122 ° C.
• the melt tension of the polypropylene-based resin composition is 2.94 cN or more and 19.6 cN or less.
• foamed particles having a low open cell ratio can be obtained by the extrusion foaming method, and the secondary moldability of the foamed particles is also good.
• the melt tension of the polypropylene-based resin composition is more preferably 3.0 cN or more, further preferably 4.0 cN or more, and particularly preferably 5.0 cN or more.
• the melt tension of the polypropylene-based resin composition is preferably 15.0 cN or less, and more preferably 13.0 cN or less.
• the melt tension of the polypropylene-based resin composition can be measured by the method described in Examples.
• the melting point Tm of the polypropylene-based resin composition is more than 150 ° C and less than 159 ° C.
• the melting point Tm of the polypropylene-based resin composition is preferably 152 ° C. or higher, more preferably 153 ° C. or higher.
• the cold crystallization temperature Tc of the polypropylene-based resin composition is 122 ° C. or higher and lower than 130 ° C.
• foamed particles having a low open cell ratio can be obtained by the extrusion foaming method, the secondary moldability of the foamed particles is improved, and the strength of the foamed molded product is also increased.
• the cold crystallization temperature Tc of the polypropylene-based resin composition is preferably 123 ° C. or higher.
• the heat of fusion ⁇ H of the polypropylene-based resin composition is 85 J / g or more and less than 100 J / g.
• foamed particles having a low open cell ratio can be obtained by the extrusion foaming method, the secondary moldability of the foamed particles is improved, and the strength of the foamed molded product is also increased.
• the heat of fusion ⁇ H of the polypropylene-based resin composition is preferably 88 J / g or more, and more preferably 91 J / g or more.
• the polypropylene-based resin composition has a mm fraction (hereinafter, also simply referred to as “mm fraction”) of 3 chains of propylene units by 13 C-NMR, which is less than 96%. It is preferably 95% or less, more preferably 94% or less. This improves the secondary moldability of the foamed particles obtained by the extrusion foaming method.
• the mm fraction of the polypropylene-based resin composition is preferably 91% or more, and more preferably 92% or more.
• the polypropylene-based resin composition preferably has a melt florate (MFR) of 1 g / 10 minutes or more and 20 g / 10 minutes or less, and 1.5 g / 10 minutes or more and 15 g / 10. It is more preferably 2 g / 10 minutes or more and 12 g / 10 minutes or less.
• MFR melt florate
• the foamed particles can be suitably obtained by the extrusion foaming method.
• the polypropylene-based resin composition is not particularly limited, but for example, one or more monomers selected from the group consisting of polypropylene-based resins, conjugated diene compounds, and aromatic vinyl compounds.
• the radical polymerization initiator is preferably produced by melt-kneading and extruding at a temperature at which the polypropylene-based resin is melted and the radical polymerization initiator is decomposed.
• a polypropylene-based material having a branched structure having a polypropylene-based resin as a main chain and a structural unit derived from one or more monomers selected from the group consisting of a conjugated diene compound and an aromatic vinyl compound as a side chain. It becomes easy to obtain a polypropylene-based resin composition containing a resin. Then, the polypropylene-based resin composition can easily satisfy the above-mentioned melt tension, melting point Tm, cold crystallization temperature Tc, heat of fusion ⁇ H, and mm fraction.
• a linear polypropylene-based resin can be preferably used, and specific examples thereof include propylene homopolymers, block copolymers, and random copolymers.
• the propylene copolymer a polymer containing 75% by mass or more of propylene is preferable because it retains the crystallinity, rigidity, chemical resistance, and the like, which are the characteristics of polypropylene-based resins.
• Monomers that can be copolymerized with propylene include ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 3,4-dimethyl-1-.
• ⁇ -olefins having 2 or 4 to 12 carbon atoms such as butene, 1-heptene, 3-methyl-1-hexene, 1-octene, 1-decene; cyclopentene, norbornene, tetracyclo [6,2,11,8,13] , 6]
• Cyclic olefins such as -4-dodecene; 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6- Diene such as octadiene; vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, ethyl acrylate, butyl acrylate, methyl methacrylate, maleic anhydride, styrene, methylstyrene, vinyltoluen
• Ethylene and 1-butene are particularly preferable from the viewpoints of improved cold brittleness and low cost. These may be used alone or in combination of two or more.
• the polypropylene-based resin is preferably a homopolymer of propylene from the viewpoint of easily obtaining a polypropylene-based resin composition satisfying the above-mentioned melt tension, melting point Tm, cold crystallization temperature Tc, heat of fusion ⁇ H and mm fraction.
• the polypropylene-based resin is not particularly limited, but the MFR is preferably 1 g / 10 minutes or more and 20 g / 10 minutes or less, more preferably 1.5 g / 10 minutes or more and 15 g / 10 minutes or less, and 2 g / 10 minutes or less. It is more preferably 10 minutes or more and 12 g / 10 minutes or less. This makes it easy to adjust the MFR of the polypropylene-based resin composition to the above-mentioned range.
• the polypropylene-based resin is not particularly limited, but has a melting point Tm of 145 ° C. or higher and 165.5 ° C. or lower, more preferably 155 ° C. or higher and 165 ° C. or lower, and 160 ° C. or higher and 165 ° C. or lower. Is even more preferable.
• Tm melting point
• the polypropylene-based resin preferably has a cold crystallization temperature Tc of 110 ° C. or higher and 125 ° C. or lower, and more preferably 113 ° C. or higher and 120 ° C. or lower.
• Tc cold crystallization temperature
• the polypropylene-based resin preferably has a heat of fusion ⁇ H of 95 J / g or more and 120 J / g or less, and more preferably 100 J / g or more and 120 J / g or less.
• a heat of fusion ⁇ H of 95 J / g or more and 120 J / g or less, and more preferably 100 J / g or more and 120 J / g or less.
• the polypropylene-based resin is not particularly limited, but the mm fraction is preferably 96% or more and 97% or less. Thereby, the melt tension, the melting point Tm, the cold crystallization temperature Tc, the heat of fusion ⁇ H and the mm fraction, particularly the mm fraction, of the polypropylene resin composition can be easily adjusted within the above-mentioned ranges.
• conjugated diene compound used as the monomer examples include butadiene, isoprene, 1,3-heptadiene, 2,3-dimethylbutadiene, 2,5-dimethyl-2,4-hexadiene and the like.
• aromatic vinyl compound used as the monomer examples include styrene; methyl such as o-methylstyrene, m-methylstyrene, p-methylstyrene, ⁇ -methylstyrene, ⁇ -methylstyrene, dimethylstyrene and trimethylstyrene.
• Styrene Styrene; chlorostyrene such as ⁇ -chlorostyrene, ⁇ -chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, dichlorostyrene, trichlorostyrene; o-bromostyrene, m-bromostyrene, p-bromo Bromostyrene such as styrene, dibromostyrene, tribromostyrene; fluorostyrene such as o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, difluorostyrene, trifluorostyrene; o-nitrostyrene, m-nitrostyrene, p.
• chlorostyrene such as ⁇ -chlorostyrene, ⁇ -chlorostyrene, o-chlorostyrene, m-ch
• -Nitrostyrene such as nitrostyrene, dinitrostyrene, trinitrostyrene; vinylphenol such as o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, dihydroxystyrene, trihydroxystyrene; o-divinylbenzene, m-divinylbenzene , Divinylbenzene such as p-divinylbenzene; isopropenylstyrene such as o-diisopropenylbenzene, m-diisopropenylbenzene, p-diisopropenylbenzene and the like.
• styrene and / or methylstyrene is preferable from the viewpoint of increasing the closed cell ratio and the foaming ratio of the foamed molded product.
• conjugated diene compounds are preferable, and butadiene and / or isoprene are particularly preferable because they are inexpensive and easy to handle, and the reaction can proceed uniformly.
• the conjugated diene compound is a copolymerizable monomer such as vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide, methacrylicamide, vinyl acetate, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, metal acrylate.
• Acrylic acid esters such as salts, metal methacrylates, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate; methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-methacrylate. It may be used in combination with a methacrylic acid ester such as ethylhexyl or stearyl methacrylate.
• the amount of the monomer added is preferably 0.04 mol or more and 0.14 mol or less, and more preferably 0.05 mol or more and 0.13 mol or less with respect to 1 kg of the polypropylene-based resin. It is more preferably 0.06 mol or more and 0.12 mol or less. This makes it easy to obtain a polypropylene-based resin composition that satisfies the above-mentioned melting tension, melting point Tm, cold crystallization temperature Tc, heat of melting ⁇ H, and mm fraction.
• the amount of the monomer added such as the conjugated diene compound is preferably 0.05 parts by mass or more and 1.5 parts by mass or less, and 0.1 parts by mass or more and 0 parts by mass with respect to 100 parts by mass of the polypropylene resin. More preferably, it is 9.9 parts by mass or less.
• the amount of the conjugated diene compound or the like added is in the above range, it is easy to obtain a polypropylene resin composition satisfying the above-mentioned melt tension, melting point Tm, cold crystallization temperature Tc, heat of fusion ⁇ H and mm fraction.
• radical polymerization initiator examples include peroxides and azo compounds.
• a polypropylene resin composition satisfying the above-mentioned melt tension, melting point Tm, cold crystallization temperature Tc, heat of fusion ⁇ H and mm fraction can be used. From the viewpoint of easy acquisition, it is preferable to use an organic peroxide, and from the viewpoint that branching can be effectively generated with a small amount of addition, it is particularly preferable to use a peroxy ester or a peroxy dicarbonate.
• peroxy ester examples include cumyl peroxy neodecanoate, 1,1,3,3-tetramethylbutyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, and t-butyl peroxy.
• Neodecanoate t-hexylperoxypivalate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 2,5-dimethyl-2, 5-Di (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t -Butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropylmonocarbonate, t-butylperoxy-2-ethylhexylmonocarbonate, t-hexylperoxy Benzoate, 2,5-dimethyl-2,5-di (benzoylper
• the peroxydicarbonate is not particularly limited, and for example, dinormal propyl peroxydicarbonate, diisopropylperoxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, and di (2-ethylhexyl) per.
• Oxydicarbonate, disec-butylperoxydicarbonate, and disetylperoxydicarbonate can be preferably used. These may be used individually by 1 type, and may be used in combination of 2 or more type.
• the amount of the radical polymerization initiator added is preferably 0.05 parts by mass or more and 3 parts by mass or less, and 0.1 parts by mass or more and 2.5 parts by mass or less with respect to 100 parts by mass of the polypropylene resin. More preferably.
• the amount of the radical polymerization initiator added is within the above range, it is possible to efficiently copolymerize the polypropylene-based resin with the monomer as a side chain. This makes it easy to obtain a polypropylene-based resin composition that satisfies the above-mentioned melt tension, melting point Tm, cold crystallization temperature Tc, heat of fusion ⁇ H, and mm fraction.
• Examples of the device for reacting the polypropylene resin, the monomer and the radical polymerization initiator include a roll, a conider, a Banbury mixer, a brabender, a kneader such as a single-screw extruder and a twin-screw extruder; a twin-screw surface.
• Examples include a horizontal stirrer such as a renewer and a twin-screw multi-disc device; a vertical stirrer such as a double helical ribbon stirrer.
• it is preferable to use a kneader, and an extruder such as a single-screw extruder and a twin-screw extruder is particularly preferable from the viewpoint of productivity.
• the polypropylene-based resin, the monomer and the radical polymerization initiator may be mixed and then melt-kneaded, or the polypropylene-based resin may be melt-kneaded and then the monomer or the radical polymerization initiator may be melt-kneaded at the same time or separately.
• the polypropylene-based resin and the radical polymerization initiator may be melt-kneaded and then the monomers may be mixed in a batch or in a divided manner.
• the temperature of the kneader may be any temperature as long as the polypropylene resin melts and the radical polymerization initiator decomposes. Preferably, it can be melt-kneaded at 150 ° C. or higher and 300 ° C. or lower.
• the melt-kneading time is generally preferably 1 minute or more and 60 minutes or less.
• the obtained polypropylene-based resin composition can contain an alcohol derived from a radical polymerization initiator, and specifically, one or more selected from the group consisting of t-butyl alcohol derived from a radical polymerization initiator and isopropanol. Alcohol can be included.
• the alcohol present in the polypropylene-based resin composition is, for example, a method in which pellets of the polypropylene-based resin composition are frozen and pulverized as a sample, and the gas component generated when heated to 150 ° C. is analyzed by the GC-MS method. Can be confirmed by.
• the polypropylene-based resin composition can be used as a base resin, and polypropylene-based resin pre-foamed particles can be obtained by an extrusion foaming method.
• the base resin may contain 10% by mass or less of a resin other than the polypropylene-based resin in addition to the polypropylene-based resin composition, or 5% by mass or less, as long as the effect of the present invention is not impaired. It may contain 3% by mass or less, or may contain 1% by mass or less. More specifically, in one or more embodiments of the present invention, the base resin may consist of 100% by mass of the polypropylene-based resin composition, and 90% by mass or more of the polypropylene-based resin composition is 100% or more.
• the polypropylene-based resin composition may be contained in an amount of 97% by mass or more and 100% by mass or less, another resin may be contained in an amount of 0% by mass or more and 3% by mass or less, and the polypropylene-based resin composition may be contained in an amount of 99% by mass or more and 100% by mass or less.
• Other resins may be contained in an amount of 0% by mass or more and 1% by mass or less.
• the other resin examples include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, and the like.
• examples thereof include polyethylene resins such as ethylene-methacrylic acid copolymers; styrene resins such as polystyrene and styrene-maleic anhydride copolymers; polyamides and the like.
• the base resin, the foaming agent, and, if necessary, the additive are melt-kneaded and then extruded, and the extruded melt-kneaded product is cut to obtain polypropylene-based resin pre-foamed particles. It is preferable that the melt-kneading is performed in two steps, and the temperature of the second step is lower than the temperature of the first step.
• the base resin, the foaming agent, and, if necessary, the additive are supplied to the first-stage extruder and melt-kneaded, and then the melt-kneaded product is melt-kneaded in the second-stage extruder whose temperature is lower than that of the first-stage extruder.
• the melt-kneaded product molten resin containing a foaming agent
• the temperature of the second-stage extruder is lower than the temperature of the first-stage extruder, the open cell ratio of the foamed particles can be easily reduced, and the moldability is improved. Further, since the main purpose of the second-stage extruder is cooling, it does not have to be an extruder as long as the purpose can be achieved. For example, a static mixer, a melt cooler, or the like can be used instead.
• the difference between the temperature of the first stage and the temperature of the second stage is preferably 5 ° C. or more, preferably 8 ° C. or more, from the viewpoint of reducing the open cell ratio of the foamed particles and improving the moldability. It is more preferably ° C. or higher, and even more preferably 10 ° C. or higher.
• the shredding method for obtaining foamed particles by the extrusion foaming method is usually roughly divided into a cold cut method and a die face cut method.
• a cold cut method a molten resin containing a foaming agent extruded from a pore die is foamed, and a strand-shaped foamed molded product is taken up and shredded while being cooled by passing through a water tank or the like (a method).
• Strand cut method can be mentioned.
• the die face cutting method is a method of cutting the molten resin extruded from the pore die with a rotating cutter while contacting the die surface or while ensuring a slight gap.
• the die face cut method is divided into an underwater cut method, a watering cut method, and a hot cut method according to the difference in the cooling method.
• both a physical foaming agent and a degradable foaming agent can be preferably used as the foaming agent.
• the physical foaming agent include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane and hexane; alicyclic hydrocarbons such as cyclopentane and cyclobutane; air, nitrogen and carbon dioxide. Inorganic gas such as gas; and water and the like.
• Specific examples of the degradable foaming agent include inorganic carbonates such as sodium bicarbonate and ammonium carbonate; organic acids such as citrate or salts thereof (sodium citrate, etc.); 2,2'-azobisiso.
• Examples thereof include azo compounds such as butyronitrile and azodicarboxylic acid amide; sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide; nitroso compounds such as N, N'-dinitrosopentamethylenetetramine (DNPT); and azide compounds such as terephthalazide. ..
• azo compounds such as butyronitrile and azodicarboxylic acid amide
• sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide
• nitroso compounds such as N, N'-dinitrosopentamethylenetetramine (DNPT)
• azide compounds such as terephthalazide. ..
• One of these foaming agents may be used alone, or two or more of them may be used in combination.
• inorganic gas and / or water is preferable from the viewpoint of safety during handling and simplification of required equipment
• the amount of the foaming agent added varies depending on the type of the foaming agent and the foaming ratio of the target polypropylene-based resin pre-foamed particles, and may be appropriately adjusted. However, it is 0.1 part by mass with respect to 100 parts by mass of the base resin. It is preferably 20 parts by mass or more, and more preferably 0.3 parts by mass or more and 15 parts by mass or less.
• the additives include cell nucleating agents (also referred to as bubble nucleating agents); colorants; antistatic agents; flame retardants; antioxidants, metal deactivators, Stabilizers such as phosphorus-based processing stabilizers, UV absorbers, UV stabilizers, fluorescent whitening agents, metal soaps, anti-acid adsorbents; cross-linking agents; chain transfer agents; lubricants; plasticizers; fillers; reinforcing materials, etc.
• Additives may be included.
• Such an additive may be prepared by preliminarily containing the additive in a resin at a high concentration to form a masterbatch, and the masterbatch resin may be added to the polypropylene-based resin mixture.
• a polyolefin resin is preferable, a polypropylene resin is more preferable, and a masterbatch can be made with the same polypropylene resin as the polypropylene resin used for the base resin of foamed particles. More preferred.
• a bubble nucleating agent may be added for the purpose of controlling the bubble shape.
• the bubble nucleating agent include sodium hydrogen carbonate, sodium hydrogen carbonate-citric acid mixture, monosodium citrate salt, talc, calcium carbonate and the like, and one of these may be used alone or two or more thereof. May be used in combination.
• the amount of the bubble nucleating agent added is not particularly limited, but is usually preferably 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the base resin.
• the extrusion discharge amount in the second-stage extruder, static mixer or melt cooler is not particularly limited, but may be, for example, 1 kg / hour or more and 1000 kg / hour or less. In the laboratory type, it may be approximately 1 kg / hour or more and 50 kg / hour or less, and in the actual production machine type, 20 kg / hour or more and 1000 kg / hour or less is preferable.
• the shape of the die used in the second-stage extruder, static mixer or melt cooler does not matter, but from the viewpoint of the appearance of the foamed particles and the ease of shaping the die, the die opening is preferably circular.
• the diameter of the portion is preferably 0.1 mm or more and 2.0 mm or less, and more preferably 0.3 mm or more and 1.0 mm or less.
• the mass of the foamed particles per particle is preferably 0.2 mg or more and 10 mg or less, and more preferably 0.5 mg or more and 6.0 mg or less.
• the mass per foamed particle is an average resin particle mass calculated based on the mass of 100 randomly selected polypropylene-based resin pre-foamed particles. When the mass per grain of the polypropylene-based resin pre-foamed particles is 0.2 mg or more, the dimensional change rate of the foamed molded product does not increase, and when it is 10 mg or less, it tends to be easily filled in the mold.
• the bulk density of the polypropylene-based resin pre-foamed particles is not particularly limited, but is preferably, for example, 20 g / L or more and 450 g / L or less, and 30 g / L or more and 300 g / L or less. More preferably.
• the bulk density of the foamed particles is within the above-mentioned range, it becomes easy to obtain a foamed molded product having a low open cell ratio and excellent compressive strength.
• the bulk density of the polypropylene-based resin pre-foamed particles can be measured by the method described in Examples.
• a foamed molded product can be produced by steam molding polypropylene-based resin prefoamed particles.
• the foamed particles are pressure-treated with an inorganic gas to impregnate the particles with the inorganic gas to obtain a predetermined internal pressure.
• a method in which the particles are applied and then filled in a mold and heat-fused with steam or the like for example, Japanese Patent Application Laid-Open No. 51-22951
• Foamed particles are compressed by gas pressure and filled in a mold to recover the particles.
• a method of heat-sealing with steam or the like using force for example, Japanese Patent Application Laid-Open No. 53-33996
• the mold is filled with foamed particles up to a predetermined gap.
• a method such as a method of compressing the closed and filled foam particles and heating and fusing with steam or the like can be used.
• the polypropylene-based resin foam molded product can be obtained by filling the polypropylene-based resin pre-foamed particles in a mold that can close but cannot seal, and heating with steam or the like to perform steam molding. it can.
• the pressure (vapor pressure) of steam during steam molding is preferably 0.40 MPa or less, and preferably 0.38 MPa or less. It is more preferably 0.36 MPa or less, and even more preferably 0.36 MPa or less.
• the polypropylene-based resin foam molded product has a higher 50% compressive strength from the viewpoint of excellent static compressive strength.
• the 50% compressive strength varies depending on the density of the foamed molded product, but for example, in the foamed molded product having a density in the range of 60 to 90 g / L, it is preferably 0.40 MPa or more, preferably 0.50 MPa or more. It is more preferable, and it is particularly preferable that it is 0.60 MPa or more.
• the 50% compressive strength of the polypropylene-based resin foam molded article can be measured by the method described in Examples.
• the density of the polypropylene-based resin foam molded product may be appropriately determined depending on the intended use and is not particularly limited, but is preferably, for example, 30 g / L or more and 300 g / L or less, preferably 40 g / L. More preferably, it is L or more and 300 g / L or less. In one or more embodiments of the present invention, the density of the polypropylene-based resin foam molded article can be measured by the method described in Examples.
• the present invention may be configured as follows in one or more embodiments.
• a polypropylene-based resin composition which satisfies the following requirements (1) to (4).
• the melting tension at 230 ° C. is 2.94 cN or more and 19.6 cN or less.
• the melting point Tm measured by differential scanning calorimetry is more than 150 ° C and less than 159 ° C.
• the cold crystallization temperature Tc measured by differential scanning calorimetry is 122 ° C or higher and lower than 130 ° C.
• the heat of fusion ⁇ H measured by differential scanning calorimetry is 85 J / g or more and less than 100 J / g.
• the polypropylene-based resin composition has a polypropylene-based resin as a main chain and a structural unit derived from one or more monomers selected from the group consisting of a conjugated diene compound and an aromatic vinyl compound as a side chain.
• the polypropylene-based resin composition according to [6] wherein the alcohol derived from the radical polymerization initiator is at least one selected from the group consisting of t-butyl alcohol and isopropanol.
• [8] The method for producing a polypropylene-based resin composition according to any one of [1] to [7], which is one or more selected from the group consisting of polypropylene-based resins, conjugated diene compounds, and aromatic vinyl compounds.
• a method for producing a polypropylene-based resin composition which comprises a step of melt-kneading and extruding the monomer and the radical polymerization initiator of the above at a temperature at which the polypropylene-based resin is melted and the radical polymerization initiator is decomposed.
• [9] The method for producing a polypropylene-based resin composition according to [8], wherein the polypropylene-based resin is a propylene homopolymer.
• a method for producing polypropylene-based resin pre-foamed particles which comprises a step of extruding and foaming the polypropylene-based resin composition according to any one of [1] to [7] to obtain polypropylene-based resin pre-foamed particles.
• a method for producing polypropylene-based resin pre-foamed particles A method for producing polypropylene-based resin pre-foamed particles.
• Manufacturing method. [16] The method for producing a polypropylene-based resin foam molded product according to [15], wherein the vapor pressure at the time of steam molding is 0.40 Mpa or less.
• a capillograph manufactured by Toyo Seiki Seisakusho Co., Ltd. was used, which was equipped with an attachment for measuring melt tension and had a cylinder with a diameter of 10 mm equipped with an orifice having a diameter of 1 mm and a length of 10 mm at the tip.
• the sample is filled in a cylinder set at 230 ° C., preheated for 5 minutes, and then the strands discharged from the orifice when the piston is lowered at a piston descent speed of 10 mm / min are hung on a pulley with a load cell 350 mm below to 1 m / min.
• the pick-up speed was increased at a rate of reaching a speed of 200 m / min in 4 minutes, and the load (unit: cN) applied to the pulley with a load cell when the strand was broken was defined as the melt tension.
• ⁇ Melting point Tm, cold crystallization temperature Tc and heat of fusion ⁇ H> 5 to 6 mg of the sample is melted by raising the temperature from 40 ° C. to 220 ° C. at a heating rate of 10 ° C./min using a differential scanning calorimeter DSC [DSC6200 type manufactured by Seiko Instruments Co., Ltd.], and then melting. Crystallization by lowering the temperature from 220 ° C to 40 ° C at a temperature lowering rate of 10 ° C / min, and then further raising the temperature from 40 ° C to 220 ° C at a heating rate of 10 ° C / min to melt the first time.
• the DSC curves at the time of raising the temperature, at the time of lowering the temperature, and at the time of the second raising of the temperature were obtained.
• ⁇ Melting point Tm The melting peak temperature obtained in the DSC curve at the time of the second temperature rise was defined as the melting point Tm. When a plurality of melting peaks were observed in the DSC curve, the melting peak existing on the highest temperature side was used.
• ⁇ Cold crystallization temperature Tc >> The crystallization peak temperature obtained in the DSC curve at the time of lowering the temperature was defined as the cold crystallization temperature Tc. When a plurality of crystallization peaks were observed in the DSC curve, the crystallization peak existing on the highest temperature side was used.
• melt flow rate (MFR) complies with the provisions of Law B described in ISO 1133 (1997), and uses a melt indexer S-01 (manufactured by Toyo Seiki Seisakusho) at 230 ° C. under a constant load of 2.16 kg. The distance that the piston moves within a certain period of time is measured, and the obtained distance and the resin density at the measured temperature are converted into the mass of the resin extruded from the orifice in 10 minutes. The fixed time is 120 seconds when the melt flow rate exceeds 0.5 g / 10 minutes and is 1.0 g / 10 minutes or less; it exceeds 1.0 g / 10 minutes and is 3.5 g / 10 minutes or less.
• a crack with a depth of about 5 mm is made on the surface of the polypropylene-based resin foam molded product with a knife, the foamed molded product in the mold is cracked along the crack, the fracture surface is observed, and the number of broken particles relative to the total number of particles in the fracture surface.
• the fusion rate of the molded product was evaluated. The case where the fusion rate was 80% or more was regarded as acceptable.
• a metal ruler is applied so as to pass through the center of the largest surface of the polypropylene resin foam molded product and parallel to the longest side, and the largest gap between the ruler and the molded product is measured.
• the numerical value was taken as the amount of deformation shrinkage. The case where the denatured shrinkage amount was 1.5 mm or less was regarded as acceptable.
• PP-1 Polypropylene homopolymer ("F113G” manufactured by Prime Polymer Co., Ltd.)
• PP-2 Propylene homopolymer ("J106G” manufactured by Prime Polymer Co., Ltd.)
• PP-3 Random copolymer of propylene and ethylene (“F724NPC” manufactured by Prime Polymer Co., Ltd.), 98% by mass of propylene
• PP-4 Polypropylene homopolymer ("J108M” manufactured by Prime Polymer Co., Ltd.)
• L / D twin-screw extruder
• a pellet-shaped polypropylene-based resin composition was obtained by shredding.
• the obtained polypropylene-based resin composition contains a polypropylene-based resin having a branched structure having a polypropylene-based resin as a main chain and a structural unit derived from a conjugated diene compound as a side chain.
• the obtained polypropylene-based resin composition contains an alcohol derived from a radical polymerization initiator, specifically t-butyl alcohol and isopropanol.
• melt-kneaded product was connected to the tip of a twin-screw extruder, passed through a melt cooler set at 164 ° C. to cool, and then pores having a diameter of 0.7 mm attached to the tip of the melt cooler.
• Polypropylene type with a mass of 1.5 to 2.0 mg / grain by extruding from a die with two holes under atmospheric pressure to foam and cutting with a rotary cutter attached to the tip of the die. Resin pre-foamed particles were obtained.
• a polypropylene-based resin foam molded product was obtained. Further, the vapor pressure of the steam used for the heat molding was sequentially lowered by 0.02 MPa, and the heat molding was repeated in the same manner as described above to obtain a foam molded product corresponding to each vapor pressure.
• the obtained foam molded product was cured in a curing room at 75 ° C. for 24 hours and then left at room temperature for 4 hours, and the fusion rate, deformation shrinkage, and surface novi were evaluated by the above evaluation method. The lowest vapor pressure at which a foam molded product that passed these requirements was obtained was defined as the minimum moldable vapor pressure.
• Example 2 [Preparation of polypropylene resin composition] Except that the polypropylene resin shown in Table 2 below was used as the raw material polypropylene resin, and the monomer shown in Table 2 below and t-butylperoxyisopropyl monocarbonate as the radical polymerization initiator were used in the blending amounts shown in Table 2 below.
• the obtained polypropylene-based resin composition contains a polypropylene-based resin having a branched structure having a polypropylene-based resin as a main chain and a structural unit derived from a conjugated diene compound as a side chain.
• the obtained polypropylene-based resin composition contains an alcohol derived from a radical polymerization initiator, specifically t-butyl alcohol and isopropanol.
• polypropylene-based resin pre-foamed particles Polypropylene resin pre-foamed particles were produced in the same manner as in Example 1 except that the polypropylene-based resin composition obtained above was used.
• polypropylene-based resin foam molded product A polypropylene-based resin foam molded product was produced in the same manner as in Example 1 except that the polypropylene-based resin pre-foamed particles obtained above were used.
• Comparative Examples 1 to 9 in Comparative Example 4, the prefoamed particles did not expand sufficiently at any of the vapor pressures, and an evaluable molded product could not be obtained.
• Comparative Example 5 although an evaluable molded product was obtained, the obtained molded product did not fill the inside of the mold due to insufficient expansion of the prefoamed particles, and a higher vapor pressure was required. It became.
• Comparative Examples 6 to 8 the obtained pre-foamed particles were in a state of being significantly shrunk immediately after being discharged from the die and hardly expanding, which was not worthy of molding evaluation.
• the melt tension at 230 ° C. was 2.94 cN or more and 19.6 cN or less
• the melting point Tm was more than 150 ° C. and less than 159 ° C.
• the cold crystallization temperature Tc was 122 ° C.
• both the point that molding with low steam pressure required for secondary molding is possible and the point that a high-strength polypropylene-based resin foam molded product can be obtained are compatible at a high level. We were able to.
• the polypropylene-based resin pre-foamed particles produced by extrusion foaming using the composition as a base material had an extremely high open cell ratio, and could not form a polypropylene-based resin foam molded product.
• the polypropylene-based resin pre-foamed particles produced by extrusion foaming using a polypropylene-based resin composition having a melting point Tm of 159 ° C. or higher and a heat of fusion ⁇ H of 100 J / g or higher as a base material are continuous. Due to the high bubble ratio, the polypropylene-based resin foam molded product could not be molded at a low steam pressure.
• the polypropylene-based resin pre-foamed particles produced by extrusion foaming using a polypropylene-based resin having a cold crystallization temperature Tc of less than 122 ° C. have an extremely high open cell ratio, and the polypropylene-based resin foam molded product.
• Tc cold crystallization temperature

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