Resin molded article

Abstract

The resin molded article contains scale-like glass and a matrix resin. The scale-like glass contained in the resin molded article has an average particle diameter of 0.1 [mu] m or more and 40 [mu] m or less and an average thickness of 0.05 [mu] m or more and 7 [mu] m or less. At least a portion of the scale-like glass surface is covered with a surface treatment agent. When the value of the mechanical strength of the resin molded article is 100, the relative value SN of the mechanical strength of the resin molded article after N times (N is at least one integer of 1-4) of a regeneration simulation test performed using an extrusion molding machine satisfies SN > = 100-2N. The mechanical strength includes at least one selected from the group consisting of maximum tensile strength, maximum bending strength, and notched cantilever impact strength.

Description

Technical Field

[0001] The present invention relates to a resin molded article, and more particularly to a resin molded article containing glass flakes and a matrix resin. Background Art

[0002] Generally, it is known that in resin molded products, glass fibers, carbon fibers, glass beads, flaky glass, mica, talc and other flaky substrates are blended into the matrix resin as fillers for the purpose of reducing warpage and deformation and / or improving mechanical strength.

[0003] For example, Patent Document 1 proposes a resin molded article formed by molding a glass-reinforced resin composition containing a thermoplastic resin (component A), glass flakes (component B), and a surface treatment deactivator (component C).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-207075 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In recent years, as part of the efforts to build a sustainable society, the demand for recycling resin molded products has increased. Generally speaking, when recycling resin molded products, the original materials such as the base resin and the release agent are separated to form particles of a resin composition, and the particles are injection molded to produce recycled molded products. Recycled molded products are used in various applications such as automobiles, motors, and electronic components. However, there are very high barriers in terms of technology and cost to separating the base resin and the flaky glass from resin molded products containing flaky glass to produce recycled molded products. Therefore, the crushed material obtained by directly crushing the resin molded products containing flaky glass is used to produce recycled molded products. Typically, a mixture of raw materials is added to the crushed material of the resin molded products containing flaky glass in a certain proportion and injection molded to produce recycled molded products. However, when using the crushed material of the resin molded products containing flaky glass to produce recycled molded products, there is a problem that the mechanical properties of the recycled molded products are reduced.

[0009] An object of the present invention is to provide a resin molded article comprising glass flakes and a matrix resin, which is suitable for suppressing a decrease in mechanical properties after recycling.

[0010] Means of solving the problem

[0011] From one aspect, the present invention provides a resin molded product comprising flake glass and a matrix resin, wherein:

[0012] The glass flakes contained in the resin molded article have an average particle size of 0.1 μm to 40 μm and an average thickness of 0.05 μm to 7 μm.

[0013] At least a portion of the surface of the glass flake is covered with a surface treatment agent,

[0014] When the mechanical strength of the resin molded product is 100, the relative value S of the mechanical strength of the resin molded product after performing N times (N is at least one integer from 1 to 4) of the regeneration simulation test using the extruder is N Satisfy S N ≥100-2N,

[0015] The mechanical strength includes at least one selected from the group consisting of maximum tensile strength, maximum flexural strength, and notched Izod impact strength.

[0016] The present invention provides a resin molded product from another aspect, comprising glass flakes and a matrix resin, wherein:

[0017] The glass flakes contained in the resin molded article have an average particle size of 0.1 μm to 15 μm and an average thickness of 0.05 μm to 7 μm.

[0018] At least a portion of the surface of the glass flake is covered with a surface treatment agent.

[0019] Effects of the Invention

[0020] According to the present invention, there can be provided a resin molded article containing glass flakes and a matrix resin, which is suitable for suppressing a decrease in mechanical properties after recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram illustrating an example of an apparatus for producing glass flakes.

[0022] Figure 2 This is a schematic diagram illustrating another example of an apparatus for producing glass flakes. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the resin molded article of the present invention will be described in detail. However, the following description is not intended to limit the present invention to the specific embodiments.

[0024] [How the Invention Was Arrived]

[0025] When crushed resin molded articles containing glass flakes are used to produce recycled molded articles, the mechanical properties of the recycled molded articles degrade. The inventors investigated the primary cause and discovered that the glass flakes contained in the resin molded articles are pulverized during the regeneration process, resulting in the formation of new fracture surfaces on the glass flakes. Conventionally, to inhibit the decomposition of the matrix resin, at least a portion of the surface of the glass flakes used in resin molded articles was coated with a surface treatment agent (e.g., Patent Document 1). However, the surface treatment agent is absent from the new fracture surfaces of the glass flakes formed by the crushing of the resin molded articles. Therefore, it is believed that the alkaline components dissolved from the fracture surfaces of the glass flakes during the high-temperature mixing and molding process in the regeneration process promote the decomposition of the matrix resin. This decomposition of the matrix resin reduces the mechanical properties of the recycled molded articles. The present invention was completed with the foregoing considerations in mind, and its embodiments are described below.

[0026] [Resin molded products]

[0027] The resin molded article of this embodiment includes glass flakes and a matrix resin. The glass flakes contained in the resin molded article have an average particle size of 0.1 μm to 40 μm and an average thickness of 0.05 μm to 7 μm. At least a portion of the surface of the glass flakes is coated with a surface treatment agent.

[0028] The mechanical strength of the resin molded article of this embodiment is 100, and the relative value S of the mechanical strength of the resin molded article after N times (No is at least one integer from 1 to 4) of the regeneration simulation test using the extrusion molding machine is N Satisfy S N ≥100-2N. As an extrusion molding machine, for example, KZW15-30MG manufactured by Technovel (molding temperature: C1 to C4, 210°C under H1, screw diameter: 15mm, rotation speed: 300rpm) can be used. The above-mentioned mechanical strength includes at least one selected from the group consisting of maximum tensile strength, maximum bending strength and notched cantilever beam impact strength. That is, in the resin molded product of this embodiment, at least one selected from the group consisting of maximum tensile strength, maximum bending strength and notched cantilever beam impact strength satisfies S N ≥100-2N.

[0029] In the resin molded product of the present embodiment, the average particle size of the flaky glass is in the range of not less than 0.1 μm and not more than 40 μm. Conventionally, the average particle size of the flaky glass contained in the resin molded product is about 50 to 600 μm. In contrast, in the resin molded product of the present embodiment, the average particle size of the flaky glass is suppressed to be small. Therefore, when the resin molded product is crushed in the regeneration process, it is difficult to form a new fracture surface on the flaky glass. Based on this, it is believed that in the regenerated molded product, the dissolution of alkaline components from the fracture surface of the flaky glass is suppressed, thereby suppressing the reduction of mechanical properties. In the resin molded product of the present embodiment, the relative value S of the mechanical strength after the regeneration simulation test using an extrusion molding machine is carried out N times (N is at least one integer from 1 to 4) is N Satisfy S N ≥100-2N, suitable for suppressing the degradation of mechanical properties after regeneration.

[0030] The glass flakes contained in a resin molded article can be removed by heating the resin molded article in an atmosphere at 625°C to remove components other than the glass flakes. The average particle size of the glass flakes contained in the resin molded article is the value obtained by dispersing the glass flakes removed by the above method in water. In this specification, the average particle size of the glass flakes refers to the particle size (D50) at which the cumulative volume from the smallest particle size in the particle size distribution of the glass flakes measured by laser diffraction and scattering methods represents 50%. The average thickness of the glass flakes can be calculated by, for example, measuring the thickness of 100 or more glass flakes using a scanning electron microscope (SEM) and dividing the total thickness by the number of measured flakes.

[0031] In this embodiment, the maximum tensile strength of the resin molded article is a value measured in accordance with JIS K 7161: 2014. The maximum flexural strength of the resin molded article is a value measured in accordance with JIS K 7171: 2022. The notched Izod impact strength of the resin molded article is a value measured in accordance with JIS K 7110: 1999.

[0032] The mechanical strength may include the maximum tensile strength, the maximum bending strength and the notched Izod impact strength. That is, in the resin molded article of this embodiment, the maximum tensile strength, the maximum bending strength and the notched Izod impact strength may all satisfy S N ≥100-2N.

[0033] Resin molded products can also meet S N ≥100-N. Satisfy S N Resin molded products with a strength of 100-N or higher are more suitable for suppressing the degradation of mechanical properties after regeneration.

[0034] The upper limit of the average particle size of the glass flakes contained in the resin molded product can be 30 μm or 15 μm. According to such a structure, when the resin molded product is crushed in the regeneration process, it is more difficult to form new fracture surfaces on the glass flakes, so that S N ≥100-2 N. The upper limit of the average particle size of the glass flakes contained in the resin molded article may be 10 μm, or further may be 5 μm.

[0035] The lower limit of the average particle size of the glass flakes contained in the resin molded article may be 0.2 μm, 0.5 μm, or even 1 μm.

[0036] The upper limit of the average thickness of the glass flakes contained in the resin molded article may be 5 μm. The lower limit of the average thickness of the glass flakes contained in the resin molded article may be 0.1 μm.

[0037] As described above, the glass flakes contained in the resin molded article have at least a portion of their surfaces covered with a surface treatment agent. In other words, the glass flakes include a surface treatment agent that covers at least a portion of the glass flakes' surfaces. The surface treatment agent content in the glass flakes is 0.05% by mass or greater and less than 10% by mass. A surface treatment agent content of 0.05% by mass or greater can inhibit the decomposition of the matrix resin. A surface treatment agent content of less than 10% by mass can prevent excess surface treatment agent from reducing the dispersibility of the glass flakes.

[0038] The content of the surface treatment agent in the glass flakes may be 8% by mass or less, 5% by mass or less, or even 3% by mass or less.

[0039] The surface treatment agent includes, for example, at least one selected from the group consisting of a binder component and a silane coupling agent.

[0040] The binder component that the surface treatment agent may contain is not particularly limited, and known binder components used for the surface treatment of flaky glass may be suitably used. Examples of the binder component include organic binder components such as methyl cellulose, carboxymethyl cellulose, starch, carboxymethyl starch, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, acrylic resin, epoxy resin, epoxy-modified polyolefin resin, phenolic resin, vinyl acetate, and polyurethane resin. Inorganic binder components include water glass, colloidal silica, and colloidal alumina.

[0041] Preferred epoxy-modified polyolefin resins include polyolefin-glycidyl methacrylate copolymers, polyolefin-allyl glycidyl ether copolymers, and copolymers obtained by grafting glycidyl methacrylate or allyl glycidyl ether with an organic peroxide. Ethylene-glycidyl methacrylate copolymers (particularly ethylene-glycidyl methacrylate graft copolymers) containing ethylene and glycidyl methacrylate as essential components are preferred. However, epoxy-modified polyolefin resins are not limited to these. Epoxy-modified polyolefin resins may be used alone or in combination of multiple types.

[0042] Examples of silane coupling agents that can be included in the surface treatment agent include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloxypropyltrimethoxysilane. Among these, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane are preferred. In addition to silane coupling agents, titanium-based coupling agents, aluminum-based coupling agents, and zirconium oxide-based coupling agents can also be used.

[0043] The surface treatment agent may contain other components as needed in addition to the above-mentioned binder component and silane coupling agent. The surface treatment agent may further contain a crosslinking agent.

[0044] The surface treatment agent may contain other components such as a polyurethane resin, a surfactant, and / or a defoaming agent, in addition to the above-mentioned components, as needed.

[0045] The method for coating the surface of the glass flakes with a surface treatment agent is not particularly limited, and known methods can be employed. For example, a solution of the surface treatment agent can be added to the glass flakes, stirred, and then dried, thereby coating at least a portion of the surface of the glass flakes with the surface treatment agent. The specific method for adding, stirring, and drying the surface treatment agent solution is not particularly limited, but an example is described below.

[0046] For example, in a mixer such as a rotating disk mixer or a Henschel mixer with rotating blades in a mixing container, the glass flakes are fluidized while a predetermined amount of binder is added using a sprayer or the like, followed by mixing and stirring. The glass flakes are then dried while stirring in the mixer, or removed from the mixer and dried. This method allows at least a portion of the surface of the glass flakes to be coated with a surface treatment agent.

[0047] As another example, by using a tumbling granulation method as described in Japanese Patent Application Laid-Open No. 2-124732, at least a portion of the surface of the glass flakes can be coated with a surface treatment agent. Specifically, the glass flakes can be placed in a horizontal vibrating granulator equipped with stirring blades and a solution of the surface treatment agent can be sprayed onto the granules to form the granules.

[0048] In addition to the above, by applying a known method generally referred to as a stirring granulation method, a fluidized bed granulation method, a spray granulation method, and a rotary granulation method, at least a portion of the surface of the glass flakes can be coated with a surface treatment agent.

[0049] The drying step is performed, for example, by heating the glass flakes coated with the surface treatment agent to a temperature equal to or higher than the boiling point of the solvent used in the surface treatment agent solution and drying the glass flakes until the solvent evaporates.

[0050] The proportion of the surface treatment agent in the glass flakes can be controlled by adjusting the concentration of the surface treatment agent in the surface treatment agent solution added or sprayed. Specifically, by adding or spraying a predetermined amount of surface treatment agent solution to a predetermined amount of glass flakes, it is possible to produce coated glass flakes having a coating film containing a predetermined proportion of the surface treatment agent.

[0051] As the composition of the glass flakes contained in the resin molded article, a known glass composition can generally be used. Specifically, glass with a low alkali metal oxide content, such as E glass, is preferably used, for example, glass having a combined Na2O and K2O content of 2% or less by mass.

[0052] The composition of the glass flakes contained in the resin molded article may be within the range of E glass.

[0053] The following is a representative composition of E-glass. The unit of the following composition is mass %. That is, the glass flakes contained in the resin molded product can contain the following components, expressed in mass %:

[0054] 52≤SiO2≤56

[0055] 12≤Al2O3≤16

[0056] 16≤CaO≤25

[0057] 0≤MgO≤6

[0058] 0≤(Na2O+K2O)≤2

[0059] 5≤B2O3≤13

[0060] 0≤F2≤0.5.

[0061] (Na2O+K2O) preferably satisfies 0≤(Na2O+K2O)≤0.8.

[0062] In addition, as another glass with a low content of alkali metal oxides, the following glass composition can be used, which contains the following components expressed in mass %:

[0063] 59≤SiO2≤65

[0064] 8≤Al2O3≤15

[0065] 47≤(SiO2-Al2O3)≤57

[0066] 1≤MgO≤5

[0067] 20≤CaO≤30

[0068] 0<(Li2O+Na2O+K2O)<2

[0069] 0≤TiO2≤5, and substantially free of B2O3, F, ZnO, BaO, SrO, and ZrO2. This glass composition was disclosed by the present applicant in International Publication No. 2006 / 068255. Glass having this glass composition is referred to as "TA-1 glass." The phrase "substantially free of" means intentionally free of these elements, excluding unavoidable inclusions such as from industrial raw materials. Specifically, this means that the content of each of B2O3, F, ZnO, BaO, SrO, and ZrO2 is less than 0.1% by mass (preferably less than 0.05% by mass, and more preferably less than 0.03% by mass).

[0070] In addition, as another glass, the following glass composition can also be used, expressed in mass %,

[0071] 60≤SiO2≤75

[0072] 5<Al2O3≤15

[0073] 3≤CaO≤20

[0074] 6≤Na2O≤20

[0075] 9≤(Li2O+Na2O+K2O)≤20. This glass composition is disclosed by the present applicant in International Publication No. 2010 / 024283. Glass having this glass composition is called "TA-2 glass."

[0076] The composition of the glass flakes is not limited to the glass compositions of E-glass, TA-1 glass, and TA-2 glass shown above. For example, glass compositions of C-glass, A-glass, ECR glass, and S-glass may also be used. The glass compositions of low-dielectric glasses disclosed by the applicant (for example, see Japanese Patent No. 6505950, Japanese Patent No. 6775159, International Publication No. 2020 / 255396, International Publication No. 2020 / 256142, International Publication No. 2020 / 256143, and International Publication No. 2021 / 049581) may also be used.

[0077] Glass flakes can be produced by, for example, the so-called blowing method disclosed in Japanese Patent Publication Nos. 41-17148 and 45-3541, or the so-called spinning method disclosed in Japanese Patent Application Laid-Open Nos. 59-21533 and 2-503669.

[0078] Blowing method can be used Figure 1 The glass manufacturing apparatus shown in FIG. The glass manufacturing apparatus comprises a refractory furnace trough 12, a blowing nozzle 15, and a press roller 17. A glass substrate 11 melted in the refractory furnace trough 12 (melting tank) is expanded into a balloon shape by gas supplied from the blowing nozzle 15, forming a hollow glass film 16. The hollow glass film 16 is crushed by the press roller 17 to produce glass flakes 1. The thickness of the glass flakes 1 can be controlled by adjusting the stretching speed of the hollow glass film 16 and the flow rate of the gas supplied from the blowing nozzle 15.

[0079] The rotation method can be used Figure 2 The glass manufacturing apparatus shown in FIG. This apparatus comprises a conduit 21, a rotating cup 22, a set of annular plates 23, and an annular cyclone collector 24. Molten glass substrate 11 is poured from conduit 21 into rotating cup 22. Centrifugal force causes it to radially flow from the upper edge of rotating cup 22, passing between annular plates 23 and drawn into the airflow before being introduced into annular cyclone collector 24. While passing through annular plates 23, the glass cools and solidifies as a thin film, then breaks into fine fragments, producing glass flakes 1. The thickness of glass flakes 1 can be controlled by adjusting the spacing between annular plates 23, the airflow velocity, and other factors.

[0080] The matrix resin contained in the resin molded article may be, for example, a thermoplastic resin. The thermoplastic resin may be at least one selected from the group consisting of polypropylene, polyethylene, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polystyrene-based resins, styrene-acrylonitrile copolymer resins, polyacrylates, styrene-butadiene-acrylonitrile copolymer resins, polyarylene sulfide, polyphenylene sulfide, polyacetal, polyamide, polyamideimide, liquid crystal polymer, polyetheretherketone, and polyetherimide.

[0081] The thermoplastic resin is preferably a resin that is not easily decomposed. Specifically, the thermoplastic resin is preferably a resin that is not easily decomposed by heat, acid, alkali, etc. Examples of such thermoplastic resins include polypropylene, polyarylene sulfide, polyamide-imide, and fluororesin. The thermoplastic resin may be polypropylene.

[0082] The content of glass flakes in the resin molded article is preferably 3 to 70% by mass. A content of 3% or more allows the glass flakes to fully function as a reinforcing material. The resin molded article is produced using a resin composition. A content of 70% or less allows the glass flakes to be evenly dispersed in the resin composition. To further minimize molding shrinkage, the content of glass flakes is more preferably 10% to 50% by mass.

[0083] Resin molded articles may also contain other components besides the glass flakes and the matrix resin. Examples of other components include fillers such as carbon black, thermoplastic elastomers, stabilizers, antioxidants, and flame retardants. Examples of stabilizers include phosphorus-based and lactone-based stabilizers. Examples of antioxidants include hindered phenol-based compounds and phosphite-based compounds. Examples of flame retardants include bromine-based, phosphorus-based, and silicone-based flame retardants. Two or more of these may also be used in combination.

[0084] Example

[0085] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0086] 〔Flake glass〕

[0087] First, by the method described below, forming, pulverization and classification, surface treatment, etc. were performed to produce glass flakes of Example 1 and Comparative Example 1, at least a portion of the surface of which was covered with a surface treatment agent.

[0088] <Molding>

[0089] Using E glass having the composition shown in Table 1, by referring to Figure 1 Glass flakes are produced using the blowing method described above. Specifically, E glass is placed in a melting tank heated to over 1200°C and melted. Thin glass sheets are formed while air is blown from a nozzle, and the thin glass sheets are continuously drawn out using rollers. By adjusting the air flow rate and roller speed, glass flakes with an average thickness of 0.7 μm are obtained.

[0090]

Table 1

[0091]

[0092] The average thickness of the glass flakes was calculated by measuring the thickness of 100 glass flakes using a SEM and dividing the total thickness by the number of measured flakes by rounding off the second decimal place.

[0093] <Crushing and Classification>

[0094] After pulverizing the glass flakes using a ball mill, they were classified to obtain glass flakes with an average particle size of 5 μm and glass flakes with an average particle size of 160 μm. The glass flakes with an average particle size of 5 μm were used as the glass flakes of Example 1. The glass flakes with an average particle size of 160 μm were used as the glass flakes of Comparative Example 1.

[0095] Furthermore, since the flaky glass has no cracks in the thickness direction, that is, in the vertical direction, the average thickness of the glass does not differ before and after pulverization.

[0096] As the ball mill, a rolling ball mill (pot mill, tube mill, cone mill, etc.), a vibrating ball mill (circular vibration mill, gyratory vibration mill, centrifugal mill, etc.), a planetary mill, etc. can be used.

[0097] In this embodiment, a ball mill is used for pulverization, but the pulverization method is not limited thereto. Regardless of whether it is a wet method or a dry method, other pulverization methods can also be used for pulverization. For example, an impact crusher, a gyratory crusher, a cone crusher, a jaw crusher, a roller crusher, a cutting mill, an autogenous mill, a pounding mill, a mortar mill, a pestle, a ring mill, a roller mill, a jet pulverizer, a hammer mill, a pin mill, a rotary mill, a vibration mill, a planetary mill, an attritor, or a bead mill can be used alone. These methods can also be used in combination as appropriate.

[0098] Classification is performed as needed. Classification is performed by screening and classification. Screening and classification may be performed in multiple times instead of just once.

[0099] For screening and classification, a dry vibrating screen can be used, for example. For example, by using a sieve with a mesh size larger than a predetermined size to remove particles with particularly large particle sizes, and then using a sieve with a mesh size smaller than a predetermined size to further remove large particles, glass flakes with a target D50 can be obtained. The mesh size of the sieve used here can be appropriately selected based on the particle size before screening and the desired D50 of the glass flakes.

[0100] In this embodiment, sieves are used for classification, but the classification method is not limited to this. Regardless of whether the method is wet or dry, other classification methods can also be used to achieve the target D50. For example, in gravity field classification, horizontal flow and vertical upflow (wet, empty tube, fluidized bed, multi-stage zigzag) can be used. In inertial force field classification, linear, curved (impact plate), and inclined (louver, Coanda effect) types can be used. In centrifugal force field classification, natural vortex and forced vortex types can be used.

[0101] The average particle size (D50) of the glass flakes was measured by dispersing the glass flakes in water using a laser diffraction particle size distribution analyzer (manufactured by MicrotracBEL Co., Ltd., model: MT3300EX, measurement mode: HRA).

[0102] Surface treatment

[0103] 5 kg of glass flakes were placed in a Henschel mixer and stirred for 15 minutes while adding a surface treatment solution using a sprayer. The surface treatment solution was prepared using water as the solvent, along with ethylene-glycidyl methacrylate copolymer as a binder and a hydrolyzed solution of γ-aminopropyltriethoxysilane as a silane coupling agent. The undried glass flakes were then removed from the mixer and dried in a dryer at 125°C for 8 hours to obtain glass flakes at least partially covered with the surface treatment agent. Hereinafter, glass flakes at least partially covered with the surface treatment agent are referred to as "coated glass flakes."

[0104] <Calculation of Silane Coupling Agent Content>

[0105] The content ratio of the silane coupling agent in the coated glass flakes that had been surface treated and dried was calculated.

[0106] <Calculation of binder content>

[0107] The content ratio of the binder in the coated glass flakes that had been surface treated and dried was calculated.

[0108] <Calculation of surface treatment agent adhesion rate>

[0109] The adhesion rate of the surface treatment agent is evaluated using the strong heat reduction method. In this embodiment, the adhesion rate of the surface treatment agent refers to the proportion of the coating film composed of the surface treatment agent in the coated glass flakes. Specifically, an appropriate amount of coated glass flakes is dried at 110°C and then heated in an atmosphere at 625°C to remove the surface treatment agent from the surface of the coated glass flakes. The adhesion rate of the surface treatment agent on the coated glass flakes is calculated based on the difference in mass between the coated glass flakes before and after heating.

[0110] [Example 1, Comparative Example 1]

[0111] Table 2 shows the measured values ​​and calculated values ​​of the coated glass flakes of Example 1 and the coated glass flakes of Comparative Example 1.

[0112]

Table 2

[0113]

[0114] 〔Resin molded products〕

[0115] Next, the resin molded articles of Example 1 and Comparative Example 1 were formed using the following method. Polypropylene (NOVATEC BC06C, manufactured by Japan Polypropylene Co., Ltd.) was used as the base resin. The coated glass flakes and polypropylene were uniformly mixed to a ratio of 30% by mass and 70% by mass, respectively. The resulting mixture was kneaded using an extruder (Technovel, KZW15-30MG, molding temperature: C1 to C4, 210°C at H1, screw diameter: 15 mm, rotation speed: 300 rpm, screw load: 6.8 amperes, resin pressure: 1.0-1.1 MPa) under molding conditions for polypropylene. This yielded a resin composition containing polypropylene as the base resin and the coated glass flakes as a reinforcing filler. No stabilizer or antioxidant was added. This resin composition was injection molded using an injection molding machine (HM7, manufactured by Nissei Plastic Industry Co., Ltd., molding temperature: 190-200°C) and dried to yield a resin molded article.

[0116] Regeneration simulation test

[0117] The recycling simulation test was conducted by extruding the resin molded article using an extruder (Technovel, KZW15-30MG, molding temperature: C1 to C4, 210°C at H1, screw diameter: 15 mm, rotation speed: 300 rpm, screw load: 6.8 amps, resin pressure: 1.0-1.1 MPa). The number of extrusions performed was defined as the number of recycling simulation tests (N). During extrusion, the base resin is heated and melted, and a strong shear force is applied to the resin molded article in the kneading section, known as the kneading zone. Therefore, it is speculated that extrusion imposes a greater load on the resin molded article than when producing recycled molded articles through pulverization and injection molding. Therefore, in this example, the resin molded article after the recycling simulation test was considered to be the resin molded article after the recycling process.

[0118] <Calculation of the Content of Glass Flakes in Resin Molded Products>

[0119] The glass flake content in resin molded articles is evaluated using the intensive heat reduction method. Specifically, an appropriate amount of resin molded articles is heated at 625°C to remove components other than glass flakes. The glass flake content in the resin molded article is calculated based on the difference between the mass of the resin molded article before heating and the mass of the residue (glass flakes) after heating.

[0120] <Measurement of particle size distribution using laser diffraction and scattering>

[0121] Particle size distribution was measured using the laser diffraction / scattering method on the glass flakes that form as residue when calculating the glass flake content in a resin molded article. Specifically, using a laser diffraction particle size distribution measuring instrument (MicrotracBEL, model: MT3300EX, measurement mode: HRA), each glass flake was dispersed in water and the particle size distribution was measured. Based on these measurement results, the D50 value of the glass flakes in the resin molded article was read. In the particle size distribution, the D50 value is defined as the particle size at which the cumulative volume, starting from the smaller particle size, corresponds to 50%.

[0122] <Measurement of characteristic values ​​of resin molded products>

[0123] The maximum tensile strength of a resin molded article was measured in accordance with JIS K 7161: 2014. The maximum flexural strength of a resin molded article was measured in accordance with JIS K 7171: 2022. The notched Izod impact strength of a resin molded article was measured in accordance with JIS K 7110: 1999.

[0124] <Calculation of Weight Average Molecular Weight of Resin Molded Products>

[0125] The weight-average molecular weight (Mw) of resin molded products is measured using gel permeation chromatography (GPC). The GPC apparatus used is a Tosoh HLC-8321GPC / HT model. Two Tosoh TSKgel GMH6-HT (7.5 x 300 mm) columns are used as separation columns, and the column temperature is set at 140°C. The measurement solvent is o-dichlorobenzene. The sample concentration is 1.0 mg / mL, and the sample injection volume is 400 μL. A differential refractometer is used as the detector. The weight-average molecular weight (Mw) is calculated using a calibration curve for known polystyrene samples.

[0126] [Example 1, Comparative Example 1]

[0127] Table 3 shows the measured values ​​and calculated values ​​of the resin molded articles of Example 1 and Comparative Example 1 and the resin molded articles after the regeneration simulation test.

[0128]

Table 3

[0129]

[0130] As shown in Tables 2 and 3, in Example 1, while the average particle size of the glass flakes decreased slightly from 5.0 μm to 4.8 μm during the production of the resin molded article, the average particle size of the glass flakes contained in the resin molded article remained virtually unchanged even after repeated recycling simulation tests (N = 1 to 4). On the other hand, in Comparative Example 1, the average particle size of the glass flakes decreased significantly from 160 μm to 42.1 μm during the production of the resin molded article, and further decreased after repeated recycling simulation tests (N = 1 to 4).

[0131] As shown in Table 3, the relative values ​​of the maximum tensile strength, maximum flexural strength, and notched Izod impact strength of the resin molded article of Example 1 after N regeneration simulation tests (N = 1 to 4) all satisfied 100-2 N. This is believed to be because the average particle size of the glass flakes in the resin molded article of Example 1 was suppressed to a small value, which prevented the formation of new fracture surfaces in the glass flakes during the regeneration simulation test. Consequently, in the resin molded article after the regeneration simulation test, the elution of alkaline components from the fracture surfaces of the glass flakes was suppressed.

[0132] As shown in Table 3, the resin molded article of Example 1 exhibited significantly less reduction in weight-average molecular weight after N (N = 1 to 4) regeneration simulation tests than the resin molded article of Comparative Example 1. This is believed to be because the elution of alkaline components from the fractured surfaces of the glass flakes in the resin molded article after the regeneration simulation test was suppressed, thereby suppressing the decomposition of the matrix resin.

[0133] From the above results, it is considered that the resin molded article of Example 1 is suitable for suppressing the reduction in mechanical properties after regeneration.

[0134] Industrial applicability

[0135] The resin molded article of the present invention is suitable for suppressing a decrease in mechanical properties after recycling and is therefore suitable for various applications such as automobiles, motors, and electronic components.

Claims

1. A resin molded article comprising glass flakes and a matrix resin, wherein: The glass flakes contained in the resin molded article have an average particle size of 0.1 μm to 40 μm and an average thickness of 0.05 μm to 7 μm. At least a portion of the surface of the scaly glass is covered with a surface treatment agent, When the mechanical strength of the resin molded product is 100, the relative value S of the mechanical strength of the resin molded product after N times of the regeneration simulation test using the extruder is N Satisfy S N ≥100-2N, where N is at least one integer from 1 to 4, The mechanical strength includes at least one selected from the group consisting of maximum tensile strength, maximum flexural strength, and notched Izod impact strength.

2. The resin molded article according to claim 1, wherein The mechanical strength includes maximum tensile strength, maximum bending strength and notched Izod impact strength.

3. The resin molded article according to claim 1, wherein Satisfy S N ≥100-N.

4. The resin molded article according to claim 1, wherein The glass flakes contained in the resin molded article have an average particle size of 15 μm or less.

5. The resin molded article according to claim 1, wherein The content ratio of the surface treatment agent in the glass flakes is 0.05 mass % or more and less than 10 mass %.

6. The resin molded article according to claim 1, wherein The glass flakes contained in the resin molded article contain the following components, expressed in mass %. 52≤SiO2≤56, 12≤Al2O3≤16, 16≤CaO≤25, 0≤MgO≤6, 0≤(Na2O+K2O)≤2、 5≤B2O3≤13, 0≤F2≤0.5。 7. The resin molded article according to claim 1, wherein The matrix resin is a thermoplastic resin.

8. The resin molded article according to claim 7, wherein The thermoplastic resin is polypropylene.

9. A resin molded article comprising glass flakes and a matrix resin, wherein: The glass flakes contained in the resin molded article have an average particle size of 0.1 μm to 15 μm and an average thickness of 0.05 μm to 7 μm. At least a portion of the surface of the scaly glass flakes is covered with a surface treatment agent.

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