Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor

Definitions

• the present invention relates to a method for producing a foam molded article.
• a method of suppressing such burrs a method of minimizing the parting line of the mold (for example, a method of making the mold corresponding to the undercut portion of the molded product into the forced removal structure instead of the slide structure).
• a method of adding a deburring agent to the resin, etc. but forced punching may not be applicable due to restrictions on product design, and when the deburring agent is added, the fluidity of the resin is impaired There is.
• the pressure at the time of injection of the supercritical fluid may in theory be made equal to or higher than the critical pressure of the fluid.
• a high pressure for example, a pressure exceeding 10 MPa
• the surface of the resulting molded article may have a rough appearance, or after the heat treatment, fine bubble-like bulging portions called blisters may be formed on the surface. As a result, the appearance of the molded article may be deteriorated.
• An object of the present invention is to provide a method for producing a foam-molded article capable of suppressing burrs while maintaining good appearance.
• the present invention relates to the following.
• the weight reduction ratio of the foam molded product obtained in the injection foam molding step for the gas having a pressure of 1 MPa or more and 10 MPa or less to the resin composition in the injection foam molding step is 3% or more to 12% with respect to the reference weight calculated from the mold dimensions.
• the manufacturing method of a foam-molded article made to contact in the quantity which becomes the following.
• flash can be provided, maintaining a favorable appearance.
• the method for producing a foam-molded product (hereinafter, also simply referred to as “molded product”) according to the present embodiment is a step of injection-foaming a resin composition containing a thermoplastic resin (hereinafter, simply referred to as “injection foam molding process” Also known as
• injection foam molding process Also known as
• a foam-molded article is a molded article which is molded by injection foam molding and has a cell structure inside.
• the resin composition contains a thermoplastic resin.
• the thermoplastic resin is not particularly limited as long as it is a thermoplastic resin that can be used for injection molding.
• a thermoplastic resin polyamide, polyester, polyethylene terephthalate (PET), acrylic, polyolefin, aramid, polyethylene naphthalate, polybutylene terephthalate, polyarylene sulfide, polyacetal, liquid crystal polymer (aromatic polyester, aromatic polyester amide, etc.), Polyimides, polyarylates, polyether imides, polyether ether ketones and the like can be mentioned. These can be used alone or in combination of two or more.
• polyamide, polyethylene terephthalate, polybutylene terephthalate, polyarylene sulfide, polyacetal, liquid crystal polymer, polyarylate, polyetherimide, polyether ether ketone, and the like are selected from the viewpoint of excellent mechanical properties, heat resistance and chemical resistance. It is preferable to contain one or more resins, and it is more preferable to contain one or more resins selected from polyarylene sulfide, polyethylene terephthalate, polybutylene terephthalate, and liquid crystal polymer in that it is further excellent in moldability, and in particular, excellent in appearance. In terms of point, polyethylene terephthalate and / or polyarylene sulfide are preferable.
• the content of the thermoplastic resin is preferably 30% by mass or more, more preferably 50% by mass or more, and more preferably 60% by mass or more in the entire resin composition in terms of sufficiently exhibiting the characteristics of the resin. Is more preferred.
• the melt viscosity of the resin composition is, based on the thermoplastic resin constituting the resin composition, based on the most added amount, if the thermoplastic resin is a crystalline resin, the melting point + 30 ° C., non-crystalline resin If it is, the melt viscosity measured at a glass transition temperature + 120 ° C and a shear rate of 1216 sec -1 is preferably 100 Pa ⁇ s or more and 600 Pa ⁇ s or less, more preferably 150 Pa ⁇ s or more and 500 Pa ⁇ s or less More preferably, it is 200 Pa ⁇ s or more and 400 Pa ⁇ s or less. By setting it in this range, it is possible to obtain a molded article having an excellent appearance and suppressing burrs while securing good moldability.
• the resin composition can include one or more resins having a melt viscosity in the above range.
• the resin composition contains an inorganic filler in an amount of 20% by mass or more, preferably 25% by mass or more, based on the entire resin composition. If the content of the inorganic filler is less than 20% by mass, fine irregularities called bumps or fine sink marks called avatars are formed on the surface of the resulting molded article, or burrs are formed, resulting in good appearance and burrs. It becomes difficult to make compatible with the suppression of
• the upper limit value of the content of the inorganic filler is preferably 70% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less in terms of securing the fluidity of the resin .
• a fibrous, particulate or plate-like inorganic filler for example, a fibrous, particulate or plate-like inorganic filler can be used.
• fibrous inorganic fillers include glass fibers, asbestos fibers, silica fibers, silica / alumina fibers, alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and further stainless steel, aluminum, titanium, Examples thereof include fibrous materials of metals such as copper and brass.
• cuttle-fish, glass flakes, various metal foil etc. can be illustrated. These inorganic fillers can be used alone or in combination of two or more.
• the size of the inorganic filler is not particularly limited as long as the effects of the present invention are not impaired.
• the average diameter of the fibrous filler can be about 1 ⁇ m to 30 ⁇ m (preferably 3 ⁇ m to 20 ⁇ m), and the average length is 100 ⁇ m to 5 mm (preferably 300 ⁇ m to 4 mm, more preferably 500 ⁇ m to 3. 5 mm).
• the average primary particle diameter of the plate-like or particulate filler can be, for example, about 1 ⁇ m to 500 ⁇ m, preferably about 10 ⁇ m to 100 ⁇ m.
• the average diameter and the average length of the fibrous filler and the average primary particle diameter of the plate-like or powder-like filler are the CCD camera for the fibrous filler, plate-like or powder-like filler before being blended in the resin composition. It is the value which analyzed the picture photographed in and was calculated by a weighted average.
• the resin composition may contain an elastomer in order to suppress a decrease in the strength (in particular, the impact resistance) of the foam-molded article.
• the type of elastomer is not particularly limited, and examples thereof include olefin-based elastomers, styrene-based elastomers, polyester-based elastomers, polyamide-based elastomers, urethane-based elastomers and core-shell-based elastomers.
• olefin elastomer are copolymers having ethylene and / or propylene as the main component, and specifically, ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-octene copolymers, ethylene -Propylene-butene copolymer, ethylene-propylene-diene copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-glycidyl methacrylate copolymer, etc. may be mentioned, but it is limited thereto It is not a thing.
• styrenic elastomers include block copolymers comprising a polymer block mainly composed of a vinyl aromatic compound such as styrene and a polymer block mainly composed of a nonhydrogenated and / or hydrogenated conjugated diene compound. However, it is not limited to this.
• polyester elastomers examples include aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate as hard segments, polyethers such as polyethylene glycol and polytetramethylene glycol, or aliphatic polyesters such as polyethylene adipate, polybutylene adipate, and polycaprolactone as soft.
• aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate as hard segments
• polyethers such as polyethylene glycol and polytetramethylene glycol
• aliphatic polyesters such as polyethylene adipate, polybutylene adipate, and polycaprolactone as soft.
• polyamide-based elastomers include, but are not limited to, block copolymers in which nylon 6, nylon 66, nylon 11, nylon 12 or the like is a hard segment and polyether or aliphatic polyester is a soft segment. It is not a thing.
• urethane elastomers include reaction of diisocyanates such as 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate and hexamethylene diisocyanate with glycols such as ethylene glycol and tetramethylene glycol.
• a polyether or polyethylene adipate such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol or an aliphatic polyester such as polybutylene adipate or polycaprolactone as a soft segment
• the core-shell elastomer is a polymer having a multi-layer structure composed of a core layer (core portion) and a shell layer covering a part or all of the core layer (surface of the core portion).
• the core layer is composed of a rubber component (soft component), and an acrylic rubber component (acrylic rubber) is particularly desirable.
• the glass transition temperature of the rubber component is, for example, less than 0 ° C. (eg, -10 ° C. or less), preferably -20 ° C. or less (eg, -180 to -25 ° C.), more preferably -30 ° C. or less (eg, -150 to -40 ° C.).
• Acrylic rubber as a rubber component is an acrylic monomer [in particular, alkyl acrylate (acrylic acid C1-12 alkyl ester such as butyl acrylate, preferably acrylic acid C1-8 alkyl, more preferably acrylic acid C2-6 alkyl ester)] Etc.] is a polymer whose main component is
• the acrylic rubber may be a homopolymer or copolymer of acrylic monomers (copolymer of acrylic monomers, copolymer of acrylic monomer and other unsaturated bond-containing monomer, etc.), acrylic It may be a copolymer of a monomer (and other unsaturated bond-containing monomer) and a crosslinkable monomer.
• the content of the elastomer is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and still more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the thermoplastic resin. It is below a mass part.
• the resin composition may be, if necessary, an antioxidant, a weathering stabilizer, a molecular weight modifier, a flowability modifier, an ultraviolet light absorber, a near infrared light absorber, an antistatic agent, a coloring agent such as a dye or pigment, a lubricant
• an antioxidant e.g., an antioxidant, a weathering stabilizer, a molecular weight modifier, a flowability modifier, an ultraviolet light absorber, a near infrared light absorber, an antistatic agent, a coloring agent such as a dye or pigment, a lubricant
• a mold release agent, a crystallization accelerator, a crystal nucleating agent, a flame retardant, a flame retardant auxiliary and the like can be contained.
• the form of the resin composition may be a powder-particle mixture, or may be a melt mixture (melt-kneaded product) such as pellets.
• the method for producing the resin composition is not particularly limited, and the resin composition can be produced using equipment and methods known in the art. For example, necessary components can be mixed and kneaded using a single- or twin-screw extruder or other melt-kneading apparatus to prepare molding pellets. A plurality of extruders or other melt kneading apparatuses may be used. Moreover, all the components may be simultaneously fed from the hopper, or some components may be fed from the side feed port.
• the above resin composition is injection foam molded.
• the injection foam molding is performed by bringing the above-mentioned resin composition into contact with a gas having a pressure of 1 MPa or more and 10 MPa or less, preferably 3 MPa or more and 8 MPa or less, and performing injection molding. If the pressure is less than 1 MPa, filling of the resin into the mold becomes insufficient and molding becomes difficult, or burrs are generated by raising the resin pressure to fill the resin into the mold. I have some troubles. When the pressure exceeds 10 MPa, the surface of the resulting molded article may have a rough appearance or blisters may be easily formed after heat treatment.
• pressurized gas can be used, and nitrogen, carbon dioxide, compressed air, fluorocarbon, hydrocarbon and the like can be mentioned.
• phase change may occur in the above-mentioned pressure range, but in the description of the present embodiment, they are collectively referred to as "gas".
• the amount of gas dissolved in the resin composition is correlated with the rate of weight loss relative to the reference weight calculated from the mold size of the resulting molded article.
• the amount of gas used in the present embodiment is 3% to 12%, preferably 5% to 10%, of the weight reduction rate of the molded article obtained in the injection foam molding step with respect to the reference weight calculated from the mold dimensions.
• the amount is as follows. By making the usage-amount of gas into said range, it can be compatible in the good appearance property and the inhibitory effect of a burr
• the adjustment of the amount of gas used can be performed by adjusting the injection amount of the molten resin into the mold. For example, the amount of gas used can be increased by reducing the injection amount of molten resin into the mold.
• the "reference weight calculated from the mold size” means the weight of a molded product obtained by filling 100% of the resin composition into the mold and molding it by ordinary injection molding which is not foam molding.
• “100% filling” means that the filling amount of the resin composition in the cavity is stabilized by securing the injection time longer than the so-called gate sealing time.
• the method of bringing the gas into contact with the resin composition can be carried out in the same manner as ordinary injection foam molding.
• it can be performed using an injection molding machine provided with a screw-provided cylinder for melting a thermoplastic resin and a container for supplying a gas into the cylinder.
• the gas supply method is not particularly limited, and may be supplied from a cylinder such as a nitrogen cylinder, a carbon dioxide cylinder, a compressed air cylinder or the like to the injection foam molding machine through the supply valve, in which case pressure reduction is performed via the pressure reduction valve. It may be supplied.
• compressed air air in the atmosphere may be compressed by a compressor or the like and supplied.
• the method for producing a foam molded article according to the present embodiment includes the step of heat-treating the molded article obtained in the injection foam molding step at 100 to 350 ° C. for 1 to 120 minutes after the injection foam molding step. It is also good. By heat treatment, the degree of crystallinity can be increased, and mechanical characteristics and dimensional stability can be enhanced. In the conventional method for producing a foam-molded article, even if the appearance of the surface of the molded article after injection foam molding is good, when a heat treatment is performed, a fine, bubble-like bulging portion (blister) is formed on the surface There is. In particular, in the reflowed solder process where heat treatment is carried out at a high temperature of 200 to 320 ° C.
• blister problems may occur in the conventional foam molded article, but the production of the foam molded article of this embodiment According to the method, even when heat treatment is performed after the injection foam molding step, blisters can be prevented from being formed on the surface, and good appearance can be maintained.
• the method for producing a foam-molded product according to the present embodiment can have a dry blending step of resin pellets and an organic foaming agent and / or an inorganic foaming agent, microcapsules, and the like, which are carried out by ordinary injection foam molding.
• the foamed molded article obtained by the method for producing a foamed molded article according to the present embodiment has a bending strength of 80% or more as a retention of a reference molded article having a weight reduction rate of 0%, which is measured according to ISO 178. Is preferably 90% or more.
• the standard molded product with a weight loss rate of 0% means that 100% of the resin composition is filled in the mold by normal injection molding that is not foam molding (in crystalline resin, the gate seal time is secured It means the molded article obtained by molding in a state where the weight is stabilized.
• the bulging part is not formed in the surface of the foam-molded article after a heat treatment process.
• the bulging part means the thing of the bubble-like fine swelling which protrudes from the surface of a foam-molded article.
• the maximum diameter is usually about 2 mm to 5 mm and the height is about 0.2 mm to 1 mm.
• the foam-molded article obtained by the method for producing a foam-molded article according to the present embodiment can be used in various applications.
• this foam-molded article is excellent in good appearance and burrs are suppressed, it can be suitably used for applications where it is preferable to use molded articles with few burrs.
• the foam-molded article obtained by the method for producing a foam-molded article according to the present embodiment can be suitably used for fluid piping parts (application of joint parts of fluid piping, application of port parts for fluid piping), and the like.
• fluid piping parts use for example, cold and warm water piping parts use can be mentioned.
• the resin composition used is as follows.
• the melt viscosity of the polyarylene sulfide resin composition (melting point: about 280 ° C.) is a value measured at 310 ° C. and a shear rate of 1216 sec ⁇ 1 .
• PPS 1 Polyarylene sulfide resin having a melt viscosity of 220 Pa ⁇ s containing 30% by mass of glass fiber (Owens Corning Japan Ltd., average length 3 mm, average diameter 10 ⁇ m) in polyarylene sulfide resin manufactured by Polyplastics Co., Ltd.
• PPS 2 Polyplastics Co., Ltd., polyarylene sulfide resin containing 40% by mass of glass fiber (Owens Corning Japan GK Co., Ltd., average length 3 mm, average diameter 10 ⁇ m), polyarylene having a melt viscosity of 160 Pa ⁇ s Sulfide resin composition
• PPS 3 Polyplastics Co., Ltd., polyarylene sulfide resin to glass fiber (Nippon Electric Glass Co., Ltd., average length 3 mm, average diameter 13 ⁇ m) 40 mass%, talc (Matsumura Sangyo Co., Ltd., average Diameter Polyarylene sulfide resin composition having a melt viscosity of 200 Pa ⁇ s, containing 13% by mass of 3 ⁇ m, and 7% by mass of glass beads (manufactured by Potters Barotini Co., Ltd., average diameter of 20 ⁇ m)
• PPS 4 Polyplastics Co., Ltd.
• PPS5 Polyarylene sulfide resin composition having a melt viscosity of 300 Pa ⁇ s containing 40% by mass of glass fiber (Nippon Electric Glass Co., Ltd., average length 3 mm, average diameter 13 ⁇ m) in polyarylene sulfide resin
• each resin composition of PPS1 to PPS5 contains about 0.2 mass% of pentaerythritol tetrastearate as a release agent, in addition to the above.
• the weight reduction rate of the foam molded article was adjusted by changing the VP injection switching position. As a result, a flat 60 mm ⁇ 60 mm ⁇ thickness 2 mm flat foam molded product (side gate 4 mm wide ⁇ 2 mm thick at the center of one side) was obtained.
• molded articles were also produced in which the molding conditions such as the pressure (gas pressure) of the gas to be injected and the resin temperature (cylinder temperature) during molding were changed as shown in Table 1.
• the mold temperature in injection foam molding of PPS1 to PPS5 was all 140 degreeC.
• the resulting foam-molded article was heat-treated at 150 ° C. for 1 hour using a heating type hot air thermostatic chamber apparatus (VTEC-75 manufactured by Isuzu Co., Ltd.). The surface of the heat-treated foam molded article was visually observed to evaluate the presence or absence of blisters. The results are shown in Table 1. 2: No blistering occurs or hardly occurs. 1: Significant blistering occurs.

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• Engineering & Computer Science (AREA)
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• Mechanical Engineering (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)
• Molding Of Porous Articles (AREA)

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Citations (6)

• 2017
  • 2017-09-29 JP JP2017189281A patent/JP6934384B2/ja active Active
• 2018
  • 2018-09-28 WO PCT/JP2018/036339 patent/WO2019065997A1/ja not_active Ceased

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