Foamed resin molded article and laminated resin molded article

Abstract

To provide a foamed resin molded object and a laminated resin molded object capable of ensuring lightweight properties due to foaming and capable of performing temperature control while keeping definite strength.SOLUTION: The foamed resin molded article 1 contains a polycarbonate resin and a phase change material. The phase change material has a content of 5.0 mass% or more and 50 mass% or less with respect to the foamed resin molded article 1. The laminated resin molded article 10 has a skin layer 2 made of a non-foamed resin on a main surface of a foamed resin molded article 1. As described above, the foamed resin molded article 1 containing a polycarbonate resin can have a function of maintaining a constant temperature by containing the PCM material in a balanced manner.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a foamed resin molded article and a laminated resin molded article in which a skin layer is laminated on a main surface of the foamed resin molded article. [Background technology]

[0002] In recent years, foamed resin molded bodies have been formed into desired shapes by thermal shaping such as vacuum forming, and are used to manufacture resin products according to their intended use. Resin products manufactured using foamed resin molded bodies as materials have attracted attention because they can be lightweight, thereby improving convenience, and can reduce carbon dioxide emissions.

[0003] It is difficult to control the size, shape, and other conditions of the bubbles formed during foam molding of a resin foam. If the size of the numerous bubbles becomes uneven, or if multiple bubbles coalesce to form irregular bubbles, this affects the strength and lightness of the resin foam and the resin product. To address this issue, it is known to add polytetrafluoroethylene (hereinafter referred to as PTFE) when molding a resin foam, as described in the following document:

[0004] WO 2008 / 038639 (Patent Document 1) discloses a foamed sheet containing 80 to 99.5% by weight of a thermoplastic resin and 0.5 to 20% by weight of PTFE. The foamed sheet has fine bubbles, and is designed to exhibit excellent surface appearance, flexibility, light weight, formability, and high light reflectivity by specifying the dispersed particle size and number of PTFE particles and the average bubble diameter perpendicular to the direction of taking up the foamed sheet.

[0005] Japanese Patent Laid-Open Publication No. 2009-1674 (Patent Document 2) discloses a foam molded article. The foam molded article is produced by foam molding a thermoplastic resin composition containing a thermoplastic resin and fluororesin particles having an average particle size of 1 to 100 μm, with the number fraction of particles having a particle size of 0.1 μm or more and less than 1.0 μm being 50% or less by number, and having a melt flow rate (JIS K7210) of 10 to 200 g / 10 min. As a result, Patent Document 2 provides a foam molded article with excellent foaming properties and soft feel.

[0006] Japanese Patent Laid-Open Publication No. 2000-72912 (Patent Document 3) discloses a foam containing a foaming nucleating agent. The foaming nucleating agent is composed of a fluororesin powder in which the total frequency of particles with a particle size of 0.1 to 0.5 μm is at least 50% by number and the total frequency of particles with a particle size of 5 μm or more is 40% by number or less. This makes it possible to produce organic polymer foams that are improved in terms of the degree of expansion, cell fineness, and foaming uniformity.

[0007] Japanese Patent Laid-Open Publication No. 2006-77218 (Patent Document 4) discloses an extruded thermoplastic resin foam to which 0.01 to 1.0 parts by weight of polytetrafluoroethylene powder is added per 100 parts by weight of the thermoplastic resin. The average particle size of the polytetrafluoroethylene powder is 0.5 μm or more and less than 1 time the average cell film thickness of the foam. This prevents a decrease in the closed cell ratio and makes the cell film uniform, improving appearance.

[0008] Japanese Patent Laid-Open Publication No. 2008-88213 (Patent Document 5) discloses a polyester foam sheet containing PTFE as a foam nucleating agent, thereby providing a foam having fine cells.

[0009] Japanese Patent Laid-Open Publication No. 2016-172872 (Patent Document 6) and Japanese Patent Laid-Open Publication No. 2014-80575 (Patent Document 7) disclose polycarbonate-based resin foam sheets for thermoforming, each of which contains a fluorine-based resin powder such as PTFE as a foaming adjuster during foaming.

[0010] Japanese Patent Laid-Open Publication No. 2001-187824 (Patent Document 8) discloses a mixed resin extruded foam board of polypropylene-based resin and polystyrene-based resin. The extruded foam board is obtained by mixing 0.01 to 0.5 parts by weight of polytetrafluoroethylene with a primary particle diameter of 1 μm or less with 100 parts by weight of polypropylene-based resin and polystyrene-based resin in an extruder, and then extruding the mixture to foam. This results in a high closed cell content, a small average cell diameter, and a low density of the extruded polypropylene-based resin foam board. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2008 / 038639 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-1674 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-72912 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-77218 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-88213 [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-172872 [Patent Document 7] Japanese Patent Application Laid-Open No. 2014-80575 [Patent Document 8] Japanese Patent Application Laid-Open No. 2001-187824 Summary of the Invention [Problem to be solved by the invention]

[0012] Foamed resin molded bodies are lightweight and have a certain strength, and because they can reduce carbon dioxide emissions compared to non-foamed resin molded bodies, they are expected to be applied in a variety of fields, such as mobile objects and building materials. However, although foamed bodies have pores inside, their thermal properties are insufficient, and further improvements are required for their application in mobile objects and building materials.

[0013] Patent Documents 1 to 8 do not fully consider the thermal properties of the resin molded product.

[0014] An object of the present disclosure is to provide a foamed resin molded article that ensures lightweight properties due to foaming, does not reduce the strength of the resin molded article, and exhibits excellent thermal properties. [Means for solving the problem]

[0015] In order to solve the above problems, the present disclosure provides the following solution. Specifically, the foamed resin molded product according to the present disclosure is a foamed resin molded product containing a polycarbonate resin, and is characterized by containing a phase change material (hereinafter referred to as PCM material) which is a latent heat material. The content of the PCM material may be 5.0% by mass or more and 50% by mass or less of the foamed resin molded product. [Effects of the Invention]

[0016] The foamed resin molded article and laminated resin molded article according to the present disclosure ensure lightweight properties due to foaming, and also contain a PCM material inside, making it possible to control temperature. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing the appearance of a foamed resin molded article according to this embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the foamed resin molded article shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] The foamed resin molded article according to the embodiment of the present disclosure may be a foamed resin molded article containing a polycarbonate resin, and may contain a PCM material having a melting point of 28°C, at which the PCM material changes from solid to liquid, in an amount of 5.0% by mass or more and 50% by mass or less relative to the foamed resin molded article.

[0019] This allows for temperature control while maintaining a certain level of strength while ensuring lightweight foaming.

[0020] Furthermore, the laminated resin molded product according to the embodiment of the present disclosure may include the foamed resin molded product and a skin layer made of a non-foamed resin laminated on one main surface of the foamed resin molded product, thereby further suppressing a decrease in strength of the foamed resin molded product after thermal shaping such as vacuum forming.

[0021] Furthermore, in the laminated resin molding, by including a PCM material in the skin layer as well, the total amount of PCM material can be increased, and the time period over which temperature can be controlled can be extended.

[0022] Hereinafter, embodiments of a foamed resin molded product 1 and a laminated resin molded product 10 according to the present disclosure will be described in detail with reference to Figures 1 and 2. Note that identical or corresponding components in the figures are denoted by the same reference numerals, and the same description will not be repeated. Note that, to facilitate understanding of the description, the drawings referred to below show simplified or schematic configurations, and some components are omitted.

[0023] The foamed resin molded body 1 contains a polycarbonate resin from the viewpoint of improving lightness and mechanical strength. However, the foamed resin molded body 1 may also contain an engineering plastic and a super engineering plastic. Engineering plastics or super engineering plastics have excellent heat resistance and mechanical strength. Engineering plastics are thermoplastic resins having a deflection temperature under load of 100°C or higher. Engineering plastics are thermoplastic resins having a deflection temperature under load of 100°C or higher. Examples of engineering plastics include polycarbonate (PC), modified polyphenylene ether (m-PPE), and syndiotactic polystyrene (SPS). Super engineering plastics are thermoplastic resins having a deflection temperature under load of 150°C or higher. Examples of super engineering plastics include polyphenylene sulfide (PPS), polysulfone (PSF), polyethersulfone (PES), polyarylate (PAR), polyamideimide (PAI), thermoplastic polyimide (PI), polyetherimide (PEI), and liquid crystal polymer (LCP). The resin material used in the foamed resin molded product 1 of the present disclosure may contain at least one selected from the group consisting of engineering plastics and super engineering plastics. For example, the polycarbonate resin content of the resin material contained in the foamed resin molded product 1 is 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more. The resin material of the foamed resin molded product 1 may contain an ultraviolet absorber, an antioxidant, etc. The deflection temperature under load is measured in accordance with ISO075-2B under a load of 1.81 MPa.

[0024] In this embodiment, the foamed resin molded body 1 contains a PCM material. The PCM material is a phase change material, and a paraffin-based latent heat storage material is preferably used. Because the PCM material undergoes a phase change between liquid and solid, it is preferably microencapsulated.

[0025] The PCM material has an average particle size of less than 40 μm. From the viewpoint of stably forming fine bubbles in the foamed resin molded body 1, the average particle size of the PCM material is preferably less than 40 μm, more preferably less than 25 μm, and even more preferably less than 10 μm, and is preferably 10 nm or more, more preferably 4 μm or more, and even more preferably 8 μm or more.

[0026] The average particle size of a PCM material is the volume-average particle size, and refers to the median diameter (D50) determined by laser diffraction / scattering particle size distribution measurement. Specifically, the volume-average particle size is determined by the following measurement method. A spray-type dry measurement using a laser diffraction particle size distribution analyzer (e.g., Shimadzu Corporation, model number "SALD-2300") is used to obtain the volume-based particle size distribution of the volatile residue described above. Using the obtained particle size distribution, the cumulative distribution for volume is subtracted from the small particle size side, and the particle size at which the cumulative 50% of all particles is determined as D50. As mentioned above, fibrous residues may occasionally occur in the volatile residue, but these should be ignored.

[0027] As described above, the foamed resin molded body 1 contains a balanced amount of PCM material, which allows temperature control while ensuring lightweight properties due to foaming and maintaining a certain level of strength.

[0028] Next, an embodiment of the laminated resin molding 10 will be specifically described with reference to Fig. 2. As shown in Fig. 2, the laminated resin molding 10 may have a skin layer 2 on at least one of the main surfaces of the foamed resin molding 1 described above. The skin layer 2 is made of a non-foamed resin. The non-foamed resin is a resin that does not contain bubbles caused by a foaming agent when the skin layer 2 is molded.

[0029] The skin layer 2 is made of, for example, polycarbonate resin. The skin layer 2 may be made of a thermoplastic resin that can adhere well to the foamed resin molded body 1. More specifically, it is particularly preferable that the resin material of the skin layer 2 is the same as that of the foamed resin molded body 1. The skin layer 2 may also contain a PCM material. This configuration of the skin layer 2 makes it possible to efficiently improve the strength while also achieving weight reduction, improved strength, and temperature control. The PCM material is the same as that contained in the foamed resin molded body.

[0030] The melt viscosity of the skin layer 2 is preferably 5500 Pa·s or more, and more preferably 7000 Pa·s. The upper limit of the melt viscosity of the skin layer 2 is not particularly limited, but is preferably 10000 Pa·s. This suppresses damage to the skin layer 2 during vacuum forming and allows the skin layer 2 to be properly formed during molding of the laminated resin molded product 10. As a result, it is possible to suppress a decrease in the strength of the resin molded product after vacuum forming of the laminated resin molded product 10. The melt viscosity is measured in accordance with ISO 11443 at a measurement temperature of 230°C, a capillary L / D of 5 / 1, and an apparent shear rate of 91 sec-1.

[0031] Next, a method for manufacturing the foamed resin molded body 1 and the laminated resin molded body 10 will be described (not shown). First, resin pellets, which will serve as the resin material, and a micro PCM material are placed into the screw cylinder of the main extruder. At this time, the PCM material may be microencapsulated. By microencapsulating the PCM material, even if it exceeds its melting point and liquefies, the liquefied PCM material on the surface of the resin molded body will not flow out. During foam molding, the resin pellets are made of, for example, polycarbonate resin. The resin pellets and PCM material are heated in a screw cylinder to produce a molten resin. Next, a blowing agent is injected into the molten resin from a blowing agent injection cylinder attached to the screw cylinder of the main extruder. The blowing agent is dissolved in the molten resin by the screw cylinder, kneaded, and uniformly dispersed. In this manner, a mixed molten resin is produced. The mixed molten resin is discharged from the die outlet to form the foamed resin molded product 1. Furthermore, when a skin layer 2 is provided, i.e., when a laminated resin molded product 10 is produced, simultaneously, resin pellets that serve as the resin material are introduced into each of the screw cylinders of the two sub-extruders and heated and melted to produce two molten resins. One of the two molten resins is discharged from the die outlet to form the skin layer 2 provided on one main surface of the foamed resin molded product 1, and the other is discharged from the die outlet to form the skin layer 2 provided on the other main surface of the foamed resin molded product 1. The mixed molten resin and the two molten resins are merged in a die from each extruder and discharged from the die outlet so that skin layers 2 are laminated on one and the other of the main surfaces of the foamed resin molded body 1. The mixed molten resin foams when extruded from the die outlet into the atmosphere. In this manner, the foamed resin molded body 1 can be produced. The foaming method may be a physical foaming method using an inert gas such as nitrogen or carbon dioxide as a foaming agent, or a chemical foaming method. The PCM material may be present in the bubbles produced by foaming. The foamed resin molded body 1 or the laminated resin molded body 10 extruded in this manner is transported to a cutting machine by a take-up machine. The cutting machine cuts the foamed resin molded body 1 or the laminated resin molded body 10 into the desired shape. The foamed resin molded body 1 and the laminated resin molded body 10 may be produced by injection molding or other methods, and are not particularly limited.

[0032] The foamed resin molded body 1 and laminated resin molded body 10 produced in this manner can be formed into desired shapes by thermal shaping such as vacuum forming and used in the following applications: For example, a wide range of products and parts, such as mobility materials and building components, including automotive interior materials, which require strength and temperature control; products and parts, such as batteries or trays for heat-generating components used in manufacturing processes involving heating, which require heat resistance and strength; or products and parts, which require weight reduction. The foamed resin molded body 1 contains polycarbonate resin and is foam-molded by coextrusion, making it suitable as a material for molding these products and parts.

[0033] Products and parts made from the foamed resin molded body 1 and the laminated resin molded body 10 can reduce the amount of resin used. As a result, the foamed resin molded body 1 according to this embodiment can contribute to improving resource utilization efficiency, easing transportation burdens, reducing energy consumption, and reducing CO2 emissions. By providing the foamed resin molded body 1 to society, it is possible to contribute to achieving Goal 7 (Affordable and Clean Energy), Goal 9 (Industry, Innovation and Infrastructure), and Goal 11 (Sustainable Cities and Communities) of the 17 Sustainable Development Goals (SDGs) established by the United Nations.

[0034] Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure.

[0035] (Example) First, a 30:70 mixture of resin pellets composed of a PCM material with a melting point of 28°C and polycarbonate was placed in a screw cylinder and foamed under low pressure under specified conditions to produce a foamed sheet with a skin layer. The resulting foamed sheet had a 3mm thick foam layer and 0.5mm thick skin layers on the top and bottom. This sheet was cut into 20cm x 20cm pieces and left at room temperature (20°C) for one hour to completely solidify the PCM material. The foamed sheet was then moved to a 35°C environment and monitored for temperature changes. The temperature retention time at 28°C, the melting point of the PCM material, was measured. The temperature rose steadily from 20°C to 28°C, but stopped rising at 28°C and was maintained at 28°C for over 30 minutes, confirming the heat storage effect. [Explanation of symbols]

[0036] 1. Foamed resin molding 2. Skin layer 10. Laminated resin molding

Claims

1. A foamed resin molded article containing a polycarbonate resin, including a phase change material; The foamed resin molded body has a content of the phase change material of 5.0 mass % or more and 50 mass % or less with respect to the foamed resin molded body.

2. The foamed resin molded article according to claim 1, The foamed resin molded article, wherein the phase change material is paraffin.

3. The foamed resin molded article according to claim 1 or 2; a skin layer made of a non-foamed resin and laminated on one main surface of the foamed resin molded body.

4. The foamed resin molded article according to claim 3, A foamed resin molded article, wherein the skin layer contains a phase change material.

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