Resin composition

Abstract

To further improve mechanical characteristics of a resin composition containing a filler and a base material compared to those of conventional resin compositions.SOLUTION: A resin composition contains a filler (1) composed of a plurality of filler particles (10), wherein each of the plurality of filler particles (10) is composed of aluminum particles (11), and an alumina film (12) which coats the surfaces of the aluminum particles (11) and is formed with a plurality of holes (14), an average value obtained by averaging the following value (I) of an opening (16) related to each of the plurality of holes (14) is 33 nm or more and 57 nm or less, and the number of holes (14) per surface 1 μm2 of the alumina film (12) is 65 pieces or more and 163 pieces or less. Expression (1): (maximum Feret diameter+minimum Feret diameter) / 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing a filler. [Background technology]

[0002] Research and development of various functional fillers to be added to electromagnetic wave shielding materials, thermally conductive materials, and electrically conductive materials has been conducted for some time now in order to improve the performance of these materials. While increasing the amount of filler added to improve various performances has been a common approach, adding too much filler reduces the toughness and mechanical strength of the aforementioned materials, and research is also underway to solve this problem. For example, Patent Document 1 discloses a porous filler that has mesopores, micropores, and macropores, and is obtained by inserting a coupling agent or the like between the layers of a layered clay mineral to make the layered clay mineral three-dimensional. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-137849 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the porous filler disclosed in Patent Document 1 does not have sufficient adhesiveness to the substrate, and there is room for improvement in the mechanical properties of a resin composition containing this porous filler and a substrate.

[0005] One aspect of the present invention has been made in consideration of the above-mentioned problems, and aims to improve the mechanical properties of a resin composition containing a filler and a base material compared to conventional resin compositions. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, a resin composition according to one aspect of the present invention is a resin composition containing a filler consisting of a plurality of filler particles, wherein each of the plurality of filler particles comprises an aluminum particle and an alumina coating having a plurality of holes formed therein, covering the surface of the aluminum particle, and wherein an average value of the following value (I) of the openings of each of the plurality of holes is 33 nm or more and 57 nm or less, and the surface of the alumina coating is 1 μm 2 The number of holes per unit area is 65 or more and 163 or less. (Maximum Feret diameter + Minimum Feret diameter) ÷ 2 (I) According to the above configuration, during the kneading of the filler and the substrate and during the molding of the kneaded product obtained by the above kneading, a portion of the substrate penetrates into the pores of the alumina coating through the openings of the pores and hardens. This creates an anchoring effect, improving the adhesion between the plurality of filler particles and the substrate compared to conventional methods. As a result, the tensile strength and elastic modulus of the resin composition containing the filler and the substrate are improved compared to conventional methods.

[0007] Furthermore, according to the above-described configuration, the plurality of filler particles and the substrate exhibit a more effective anchoring effect, thereby improving the adhesion between the plurality of filler particles and the substrate compared to conventional methods, thereby improving the tensile strength of the resin composition compared to conventional methods.

[0008] In the resin composition according to one aspect of the present invention, the relationship between the average value of the (I) values ​​for the openings of the plurality of holes and the tensile shear stress generated at the interface between the filler and the substrate may be expressed by the following formula (II): Y=-0.030X1 2 +2.7X1-45···(II) Y: Tensile shear stress [MPa] X1: Average Feret pore diameter [nm] (33≦X1≦57) The resin composition according to one embodiment of the present invention is 2 The relationship between the number of holes per unit area and the tensile shear stress generated at the interface between the filler and the substrate may be expressed by the following formula (III): Y=-0.00080X2 2 +0.12X2+14···(III) Y: Tensile shear stress [MPa] X2: Unit number of holes [pcs / μm2 ](65≦X2≦163) In the resin composition according to one aspect of the present invention, the average perimeter of the openings of the plurality of holes may be 103 nm or more and 186 nm or less. This configuration allows the plurality of filler particles and the substrate to more effectively exert an anchoring effect, thereby improving adhesion between the plurality of filler particles and the substrate compared to conventional methods. This results in a resin composition with a higher tensile strength compared to conventional methods.

[0009] In a filler according to one embodiment of the present invention, the average value of the following (IV) for the openings of the plurality of holes may be 7 nm or more and 11 nm or less: Area / Peripheral Length (IV). According to this configuration, the anchoring effect between the plurality of filler particles and the substrate is more effectively exerted, thereby improving the adhesion between the plurality of filler particles and the substrate more than ever before. This results in a resin composition with a tensile strength that is more improved than ever before.

[0010] The resin composition according to one aspect of the present invention may be used for electromagnetic wave shielding. According to the above-described configuration, it is possible to realize an electromagnetic wave shielding resin composition having improved tensile strength and elastic modulus compared to conventional resin compositions.

[0011] The electromagnetic wave shielding resin composition according to one aspect of the present invention may contain the filler according to one aspect of the present invention in an amount of 3 volume % or more. According to this configuration, it is possible to realize an electromagnetic wave shielding resin composition having improved tensile strength compared to conventional resin compositions. [Effects of the Invention]

[0012] According to one aspect of the present invention, the tensile strength and modulus of elasticity of a resin composition containing a filler and a base material can be improved compared to conventional resin compositions. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an external view showing a resin composition according to one embodiment of the present invention. [Figure 2]FIG. 2 is a cross-sectional view showing a main part of a filler particle according to one embodiment of the present invention. [Figure 3] 2 is a flowchart showing an example of a method for producing the resin composition shown in FIG. [Figure 4] Reference numeral 1041 is a histogram showing the distribution of maximum Feret particle diameters of filler particles according to an example of the present invention. Reference numeral 1042 is a histogram showing the distribution of minimum Feret particle diameters of filler particles according to an example of the present invention. Reference numeral 1043 is a histogram showing the distribution of particle size aspect ratios of filler particles according to an example of the present invention. [Figure 5] Reference numeral 1051 is a histogram showing the distribution of maximum Feret pore diameters of filler particles according to an example of the present invention. Reference numeral 1052 is a histogram showing the distribution of minimum Feret pore diameters of filler particles according to an example of the present invention. Reference numeral 1053 is a histogram showing the distribution of pore size aspect ratios of filler particles according to an example of the present invention. [Figure 6] 1 is a histogram showing the distribution of the thickness of the alumina coating on filler particles according to an example of the present invention. [Figure 7] 1A to 1C are diagrams showing the state of each molded product according to the first to third comparative examples of the present invention and the molded products according to the first to third examples of the present invention when viewed from above. [Figure 8] 1 is a graph showing the tensile stress of each of the molded articles according to the first to third comparative examples of the present invention and the molded articles according to the first to third examples of the present invention. [Figure 9] 1 is a graph showing the elastic modulus of each molded article according to first to third comparative examples of the present invention and each molded article according to first to third examples of the present invention. [Figure 10] Reference numeral 1101 is a graph showing the amount of attenuation of the electric field strength of the molded article according to the third comparative example of the present invention. Reference numeral 1102 is a graph showing the amount of attenuation of the electric field strength of the molded article according to the third example of the present invention. [Figure 11]Reference numeral 1111 is a graph showing the attenuation of magnetic field strength of the molded article according to the third comparative example of the present invention. Reference numeral 1112 is a graph showing the attenuation of magnetic field strength of the molded article according to the third example of the present invention. [Figure 12] 1 is a graph showing the relationship between the addition rate and the tensile stress for a filler according to a comparative example of the present invention and a filler according to an example of the present invention. [Figure 13] Reference numeral 1301 denotes a top view of each test piece according to the fourth to sixth examples of the present invention, and reference numeral 1302 denotes a side view showing the state in which each test piece according to the fourth to sixth examples of the present invention is placed on a hot plate. [Figure 14] 1 is a graph showing the relationship between the average Feret pore diameter of the openings of the pores on the surface of the filler particles contained in each test specimen and the tensile shear stress when a tensile shear test was conducted on each test specimen according to the fourth to sixth examples of the present invention and each test specimen according to the fourth to sixth comparative examples of the present invention. [Figure 15] 1 is a graph showing the relationship between the number of unit pores of the openings of pores on the surface of a filler particle contained in each test piece and the tensile shear stress when a tensile shear test was conducted on each test piece according to the fourth to sixth examples of the present invention and each test piece according to the fourth to sixth comparative examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Configuration of Resin Composition] The structure of a resin composition 100 according to one embodiment of the present invention will be described with reference to FIGS. 1 and 2. The resin composition 100 is used, for example, as an electromagnetic wave shielding material, a thermally conductive material, or a conductive material. That is, the resin composition 100 is used, for example, as an electromagnetic wave shielding resin composition, a thermally conductive resin composition, or a conductive resin composition. Examples of electromagnetic wave shielding materials include materials for battery cases, materials for cables, and materials for wire harnesses. Examples of thermally conductive materials include materials for various heat generating elements and materials for various heat dissipating elements. Examples of conductive materials include sensing materials, antistatic materials, materials for wearable devices, robot devices, electrostatic coating base materials, copier materials, resin pastes, wiring layers, electrodes, adhesive tapes, and the like.

[0015] As shown in FIG. 1, a resin composition 100 is composed of a filler 1 and a resin 2 as a base material. The filler 1 is a filler added to the resin 2 and is composed of a plurality of filler particles 10. In this embodiment, the filler particles 10 have a substantially cylindrical shape, but there are no particular limitations on the shape and particle size of the filler particles 10. For example, the filler particles 10 may be in the shape of a substantially polygonal prism (such as a substantially triangular prism, a substantially square prism, a substantially pentagonal prism, or a substantially hexagonal prism), a foil, or a plate.

[0016] There are also no particular limitations on the type of resin 2, and thermoplastic resins, thermosetting resins, etc. can be used. Examples of thermoplastic resins include polypropylene, polyethylene, polyvinyl chloride, polyvinyl acetate, polystyrene, ABS resin, polyacrylonitrile, acrylonitrile styrene, acrylic, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyamide (e.g., nylon 4, nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 612, nylon 6-12, nylon 6-66, nylon MXD6), polyacetal, polyphenylene ether, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyether ether ketone, thermoplastic polyimide, liquid crystal polymer, fluororesin, polyarylate, polysulfone, polyether sulfonate, etc. Examples of suitable resins include polyolefins, polyamideimides, polyetherimides, polyetheramides, polyetheretheramides, polyetheramideimides, polyethersulfones, phenoxy resins, ionomers, polylactic acid, polyhydroxyalkanoates, polybutylene succinate, polybutylene succinate adipate, and various thermoplastic elastomers such as styrenes, polyolefins, polyvinyl chlorides, polyurethanes, polyesters, polyamides, polybutadienes, trans-polyisoprenes, fluorine-containing elastomers, fluorine rubbers, and chlorinated polyethylenes, as well as copolymers, blends, and polymer alloys based on these materials, and biomass plastics containing renewable organic resources such as plants. These resins can be used singly or in combination. Note that the term "resin" as used herein includes rubber and elastomers.

[0017] Examples of thermosetting resins include phenolic resins, urea resins, melamine resins, alkyd resins, unsaturated polyester resins, epoxy resins, silicone resins, polyurethane resins, polyimide resins, diallyl phthalate resins, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, nitrile rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, urethane rubber, silicone rubber, fluororubber, ethylene vinyl acetate rubber, epichlorohydrin rubber, and polysulfide rubber, and these may be used alone or in combination of two or more.

[0018] Furthermore, known additives that can be used when forming the resin composition 100 can be blended into the resin composition 100 as needed. Examples of additives that can be blended into the resin composition 100 include thickeners, viscosity reducers, plasticizers, crystal nucleating agents, crystallization accelerators, crystallization retarders, lubricants, release agents, reinforcing agents, crosslinking agents, alloying agents, compatibilizers, fillers, rubber reinforcing agents, fibrous reinforcing agents, flame retardants, flame retardant assistants, smoke reducing agents, antifogging agents, conductive agents, antistatic agents, thermal conductive agents, ballooning agents, foaming agents, colorants, fluorescent agents, lightweight fillers, high specific gravity metals, weathering agents, ultraviolet absorbers, light stabilizers, thermal decomposition inhibitors, hydrolysis resistance inhibitors, fungicides, antibacterial agents, metal deactivators, as well as adhesion improvers such as silane coupling agents, titanium coupling agents, and acid anhydrides, nonionic surfactants, and wettability improvers such as fluorine-based surfactants. These can be used alone or in combination.

[0019] Note that impurities may be mixed into the filler 1 and the resin composition 100 during their respective manufacturing processes. That is, the resin composition 100 may consist of the filler 1, the resin 2, and impurities. Furthermore, the resin composition 100 may contain additives in addition to the filler 1 and the resin 2.

[0020] 2, filler particles 10 are composed of aluminum particles 11 and alumina coatings 12 that cover the surfaces of the aluminum particles 11. Here, "covering the surfaces of the aluminum particles 11" does not mean that the surfaces of the aluminum particles 11 are completely covered by the alumina coatings 12, but rather includes, for example, a state in which part of the surface of the aluminum particles 11 is inevitably exposed from the alumina coatings 12 that cover the aluminum particles 11 during the production process of the filler particles 10.

[0021] 2 is a schematic diagram of the interface between the filler 1 and the resin 2 and the surrounding area. Specifically, the diagram shows a state in which a part of the resin 2, which is the base material, penetrates into the hole 14 (details in the next paragraph) of the alumina coating 12 through the opening 16 of the hole 14 and hardens, thereby exerting an anchor effect.

[0022] The alumina coating 12 is porous and consists of multiple coating cells 13. Holes 14 are formed in the coating cells 13. In other words, multiple holes 14 are formed in the alumina coating 12. There are no particular limitations on the shape or size of the holes 14, but the holes 14 in this embodiment are assumed to be small pores extending from the surface of the alumina coating 12 toward the surfaces of the aluminum particles 11. The bottom of the alumina coating 12 forms a barrier layer 15, which is in contact with the surfaces of the aluminum particles 11. The barrier layer 15 is an oxide coating formed in the early stage of the anodizing treatment. Openings 16 corresponding to each of the multiple holes 14 are formed on the surface of the alumina coating 12, i.e., the surface of the filler particles 10.

[0023] The filler particles 10 preferably have the following configuration. First, the filler particles 10 preferably have an average value of "(maximum Feret diameter + minimum Feret diameter) ÷ 2" of the openings 16 associated with each of the plurality of holes 14 formed in the alumina coating 12, of 33 nm or more and 57 nm or less. Hereinafter, "(maximum Feret diameter + minimum Feret diameter) ÷ 2" of the openings 16 will be referred to as the "Feret pore diameter." Hereinafter, the average value of "(maximum Feret diameter + minimum Feret diameter) ÷ 2" of the openings 16 associated with each of the plurality of holes 14 formed in the alumina coating 12 will be referred to as the "average Feret pore diameter."

[0024] Here, the Feret diameter of the opening 16 is the shortest distance between two imaginary parallel tangents sandwiching the outer edge of the opening 16 in a plan view. The maximum Feret diameter of the opening 16 is the maximum value of the shortest distance between the two imaginary parallel tangents when the two imaginary parallel tangents are rotated from 0° to 180° around the central axis (not shown) of the opening 16. The minimum Feret diameter of the opening 16 is the minimum value of the shortest distance between the two imaginary parallel tangents when the two imaginary parallel tangents are rotated from 0° to 180° around the central axis of the opening 16.

[0025] The filler particles 10 are formed within 1 μm of the surface of the alumina coating 12. 2 The number of pores 14 per unit area (hereinafter referred to as "unit pore number") is preferably 65 to 163. Furthermore, the filler particles 10 preferably have an average value (hereinafter referred to as "average perimeter") of the perimeters of the openings 16 associated with the plurality of pores 14 formed in the alumina coating 12 of 103 nm to 186 nm.

[0026] Furthermore, the filler particles 10 preferably have an average value of "area divided by perimeter" of the openings 16 associated with each of the plurality of holes 14 formed in the alumina coating 12, of 7 nm or more and 11 nm or less. Hereinafter, the "area divided by perimeter" of the openings 16 will be referred to as the "area ratio." Hereinafter, the average value of "area divided by perimeter" of the openings 16 associated with each of the plurality of holes 14 formed in the alumina coating 12 will be referred to as the "average area ratio." Meanwhile, the resin composition 100 preferably has a filler 1 addition rate of 3 vol (volume) % or more.

[0027] [Method for producing resin composition] A method for producing the resin composition 100 will be described with reference to Fig. 3. Note that the content of the production method and the order of each step shown in the flowchart of Fig. 3 are merely examples, and other production methods may be adopted, or the order of some of the steps may be changed.

[0028] Examples of methods other than the manufacturing method shown in the flowchart of FIG. 3 include, for example, adding a new water washing step as needed when the first water washing step or the second water washing step (both described below) is insufficient. Another example is omitting at least one of the first drying step and the second drying step (both described below) as needed when there is no effect from water droplets attached in the first water washing step or the second water washing step. Another example is omitting the first cutting step (described below) when aluminum wire, the raw material for filler particles 10, is processed continuously without cutting. Another example is a method in which filler particles 10 obtained by cutting aluminum wire are previously mixed and molded with resin 2, and the filler particles 10 integrated with resin 2 are anodized, and then mixed and molded again as a master batch.

[0029] As shown in FIG. 3, first, in step S (hereinafter abbreviated as "S") 101, aluminum wire, which is the raw material for filler particles 10, is cut into multiple pieces with a predetermined length, for example, approximately 30 cm, and the resulting wire pieces are manually stretched into a substantially straight shape (first cutting step). Next, in S102, a commercially available alkaline cleaning solution (Contaminon (registered trademark) L; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is diluted with water (for example, 40 times) and poured into a beaker, and multiple substantially straight wire pieces are placed therein. The beaker containing the wire pieces is then placed in a commercially available ultrasonic cleaner and washed for a predetermined time, for example, approximately 15 minutes, to degrease the surface of the wire pieces (pretreatment step).

[0030] Next, in S103, the degreased wire pieces are washed with water for a predetermined time, for example, about 1 minute (first washing step). Next, in S104, the water adhering to each of the washed wire pieces is wiped off with a rag or the like, and the wire pieces are dried in a commercially available desiccator (first drying step).

[0031] Next, in S105, an anodization treatment is performed. Specifically, the dried wire piece is immersed as an anode and a commercially available aluminum foil as a cathode in a predetermined electrolyte, for example, a 16 wt (weight) % phosphoric acid aqueous solution at about 15°C. Then, using a commercially available DC power supply, a predetermined current is passed through the anode and cathode for a predetermined time (anodization treatment step). The predetermined current value is, for example, about 1.5 mA / cm. 2 and the predetermined time is, for example, about 30 minutes.

[0032] Next, in S106, the anodized wire pieces are washed with water for a predetermined time, for example, about 1 minute (second washing step). Next, in S107, the water adhering to each of the washed wire pieces is wiped off with a rag or the like, and the wire pieces are dried in a commercially available desiccator (second drying step).

[0033] Next, in S108, the dried wire pieces are cut into pieces of a predetermined length, for example, about 0.5 mm, using a commercially available cutter (second cutting step). When the process in S108 is completed, the filler 1 consisting of a plurality of filler particles 10 having a substantially cylindrical shape is completed.

[0034] Next, in S109, the filler 1 and resin 2 are manually kneaded and stirred at room temperature of about 20°C (kneading step). For example, Flowblen QB200 (manufactured by Sumitomo Seika Chemicals Co., Ltd.), a type of thermoplastic polypropylene resin, is used as the resin 2. The addition rate of the filler 1 can be set arbitrarily.

[0035] Next, in S110, the kneaded mixture of filler 1 and resin 2 is press-molded using a commercially available press (1000k NC type testing machine; manufactured by Osaka Jacqui Co., Ltd.) to complete resin composition 100 (molding step). For example, the kneaded mixture is press-molded into a 150 mm square piece with a thickness of 1.4 mm at a room temperature of approximately 20°C under conditions of a heating rate of approximately 20°C / min, a molding temperature of 220°C, a press pressure of 800 kN, and a press time of 10 minutes. The press-molded mixture is then cooled to room temperature to complete resin composition 100. Note that if resin 2 is a thermoplastic resin, injection molding may be used instead of press molding.

[0036] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0037] [Example] Examples of the present invention will be described below with reference to Figures 4 to 15. First, a filler according to an example of the present invention (hereinafter referred to as "this filler") was produced by the same method as in the above-described embodiment, and then various indices showing the state of this filler were measured and calculated. In this example, an aluminum wire (manufactured by Good Fellow) with a diameter of 0.5 mm, a length of 500 m, and a purity of 99.5% (the remaining 0.5% being impurities) was used as the raw material for the filler particles that make up this filler and the untreated filler described below.

[0038] Images of this filler generated by a commercially available digital microscope were analyzed using ImageJ (National Institutes of Health, USA). Specifically, the maximum and minimum Feret particle sizes were measured for each of the 1,051 filler particles captured in the image of this filler, and the particle size aspect ratio was calculated. The maximum Feret particle size is the maximum Feret diameter when the particle size of the filler particle is expressed in Feret diameters. The minimum Feret particle size is the minimum Feret diameter when the particle size of the filler particle is expressed in Feret diameters. The particle size aspect ratio is the value obtained by dividing the maximum Feret particle size by the minimum Feret particle size. The results are shown in Figure 4.

[0039] Images of this filler generated using a commercially available SEM (scanning electron microscope) were also analyzed using ImageJ. Specifically, the maximum and minimum Feret pore diameters were measured for each of the 1,087 pores captured in the image of this filler, and the aspect ratio of the pore diameters was calculated. The maximum Feret pore diameter is the maximum Feret diameter when the diameter of the opening of the pores formed on the surface of the filler particle is expressed in Feret diameters. The minimum Feret pore diameter is the minimum Feret diameter when the diameter of the opening of the pores formed on the surface of the filler particle is expressed in Feret diameters. The aspect ratio of the pore diameter is the value obtained by dividing the maximum Feret pore diameter by the minimum Feret pore diameter. The results are shown in Figure 5.

[0040] In addition, a total of 11 images of different regions of this filler were generated using the SEM mentioned above, and the thickness of the alumina coating on a total of 100 filler particles randomly selected from each of the 11 images was measured and calculated. The results are shown in Figure 6.

[0041] Next, a molded product according to a first example of the present invention, a molded product according to a second example of the present invention, and a molded product according to a third example of the present invention were each produced, and the surfaces of each molded product were visually observed. Hereinafter, the molded product according to the first example of the present invention will be referred to as "first example product 111," the molded product according to the second example of the present invention will be referred to as "second example product 121," and the molded product according to the third example of the present invention will be referred to as "third example product 131."

[0042] Specifically, the resin compositions that served as the bases for the first to third example products 111 to 131 were manufactured using the filler and resin 2 in the same manner as in the previously described embodiment. In the first to third examples, polypropylene was used as resin 2. In the manufacture of the resin composition that served as the base for the first example product 111, the filler was added at a rate of 20 vol%. In the manufacture of the resin composition that served as the base for the second example product 121, the filler was added at a rate of 40 vol%. In the manufacture of the resin composition that served as the base for the third example product 131, the filler was added at a rate of 60 vol%. The manufactured resin compositions were then press-molded using a press similar to that used in this embodiment to produce the first to third example products 111 to 131, each measuring 150 mm square and 1.4 mm thick. The press molding conditions were also similar to those used in this embodiment.

[0043] Furthermore, using untreated filler and resin 2, a molded product according to a first comparative example of the present invention, a molded product according to a second comparative example of the present invention, and a molded product according to a third comparative example of the present invention were each produced. Hereinafter, the molded product according to the first comparative example of the present invention will be referred to as "first comparative product 110," the molded product according to the second comparative example of the present invention will be referred to as "second comparative product 120," and the molded product according to the third comparative example of the present invention will be referred to as "third comparative product 130." "Untreated filler" refers to a filler composed of a plurality of aluminum particles. In other words, it refers to a filler in which the filler particles are aluminum particles. The untreated filler was produced by following the steps S101 and S108 in the flowchart of Figure 3.

[0044] The manufacturing method for the first comparative product 110 to the third comparative product 130 was the same as the manufacturing method for the first practical product 111 to the third practical product 131. The additive rate of untreated filler in the first comparative product 110 was 20 vol%, the additive rate of untreated filler in the second comparative product 120 was 40 vol%, and the additive rate of untreated filler in the third comparative product 130 was 60 vol%.

[0045] The surfaces of the first example product 111 to the third example product 131 and the first comparison product 110 to the third comparison product 130 were in the state shown in FIG. 7. Specifically, in all of the first comparison product 110 to the third comparison product 130, the untreated filler was unevenly dispersed at the edges. On the other hand, in all of the first example product 111 to the third example product 131, the filler was uniformly dispersed. This result is presumably because the filler has stronger adhesion to the resin 2 than the untreated filler, and therefore the multiple filler particles that were once uniformly dispersed during the production process of the first example product 111 to the third example product 131 remained in their original positions without flowing.

[0046] Next, a test piece according to a first example of the present invention, a test piece according to a second example of the present invention, and a test piece according to a third example of the present invention were prepared, and the mechanical properties of each test piece were evaluated. Hereinafter, the test piece according to the first example of the present invention will be referred to as the "first example specimen," the test piece according to the second example of the present invention will be referred to as the "second example specimen," and the test piece according to the third example of the present invention will be referred to as the "third example specimen."

[0047] Specifically, the first example product 111 was cut to a width of 20 mm to form a first example piece that was rectangular in plan view, the second example product 121 was cut to a width of 20 mm to form a second example piece that was rectangular in plan view, and the third example product 131 was cut to a width of 20 mm to form a third example piece that was rectangular in plan view. The first comparative product 110 was cut to a width of 20 mm to form a first comparative piece that was rectangular in plan view, the second comparative product 120 was cut to a width of 20 mm to form a second comparative piece that was rectangular in plan view, and the third comparative product 130 was cut to a width of 20 mm to form a third comparative piece that was rectangular in plan view. The first comparative product corresponds to the test piece according to the first comparative example of the present invention, the second comparative product corresponds to the test piece according to the second comparative example of the present invention, and the third comparative product corresponds to the test piece according to the third comparative example of the present invention.

[0048] Tensile tests were performed on each of the first to third example specimens and the first to third comparative specimens using a commercially available tensile tester with a chuck distance of 85 mm and a tensile speed of 1.0 mm / min.

[0049] The results of the tensile stress are shown in Figure 8. Specifically, the tensile stress of the first example specimen was approximately 1.2 times that of the first comparative specimen, the tensile stress of the second example specimen was approximately 1.5 times that of the second comparative specimen, and the tensile stress of the third example specimen was approximately twice that of the third comparative specimen. These results demonstrate that the high adhesiveness of the filler results in improved tensile strength of resin compositions containing the filler compared to conventional ones.

[0050] The results of the elastic modulus are shown in Figure 9. Specifically, the elastic modulus of the first example specimen was approximately 1.3 times that of the first comparative specimen, the elastic modulus of the second example specimen was approximately 1.9 times that of the second comparative specimen, and the elastic modulus of the third example specimen was approximately 2.4 times that of the third comparative specimen. These results demonstrate that the high adhesiveness of the filler results in an improved elastic modulus of the resin composition containing the filler compared to conventional resin compositions.

[0051] The attenuation of the electric field intensity and the magnetic field intensity was measured for each of the third experimental specimen and the third comparative specimen. Specifically, an electromagnetic shielding effectiveness measuring device (a device for measuring near-field electric field shielding effectiveness and a device for measuring near-field magnetic field shielding effectiveness) manufactured by the KEC Kansai Electronics Industry Promotion Center (KEC) was used in accordance with the KEC method, and measurements were made at frequencies ranging from 0.1 MHz to 1000 MHz. More specifically, measurements were made three times for each specimen, and each measurement result was subjected to a five-point moving average process. The average value (solid line in FIG. 10) of the three data points obtained by the moving average process (dashed lines in FIG. 10) was then calculated to represent each attenuation value.

[0052] The results of the attenuation of the electric field strength are shown in Figure 10. Specifically, the third example specimen had a greater attenuation than the third comparison specimen across almost all frequency bands measured. This result demonstrates that the electric field shielding effect of the resin composition containing this filler is improved compared to conventional resin compositions. The results of the attenuation of the magnetic field strength are shown in Figure 11. Specifically, the third example specimen had a greater attenuation than the third comparison specimen across the frequency band of approximately 10 MHz or higher measured. This result demonstrates that the magnetic field shielding effect of the resin composition containing this filler is improved compared to conventional resin compositions.

[0053] It is believed that these effects were achieved because the filler has higher adhesion to resin 2 than the untreated filler, thereby reducing the flow of filler particles that occurs during the production process of the third embodiment product 131 and maintaining a high density of filler particles in the third embodiment product 131.

[0054] Using the results shown in FIG. 8, the relationship between the addition rate and tensile stress for the present filler and untreated filler was graphed. As a result, two approximation curves (solid and dashed lines in the figure) were obtained, as shown in FIG. 12. In FIG. 12, an addition rate of 0 vol% represents the case where only resin 2 is used, with no filler mixed in. Also, in the figure, the lower limit of effect manifestation, 3 vol%, represents the value at the intersection of the approximation curve for the case where anodizing treatment is performed and the approximation curve for the case where anodizing treatment is not performed. The results shown in FIG. 12 revealed that when the addition rate is 3 vol% or more and 60 vol% or less, the tensile strength of resin compositions containing the present filler is significantly improved compared to resin compositions containing untreated fillers.

[0055] Next, a test piece according to a fourth example of the present invention, a test piece according to a fifth example of the present invention, and a test piece according to a sixth example of the present invention were fabricated, and the mechanical properties of each test piece were evaluated. Hereinafter, the test piece according to the fourth example of the present invention will be referred to as "fourth example specimen 140," the test piece according to the fifth example of the present invention will be referred to as "fifth example specimen 150," and the test piece according to the sixth example of the present invention will be referred to as "sixth example specimen 160."

[0056] The fourth example specimen 140 to the sixth example specimen 160 were prepared as follows. That is, an aluminum plate (thickness: 0.5 mm) made of the same material as the aluminum particles constituting this filler was cut to prepare two rectangular test pieces in plan view, each 10 mm wide and 100 mm long, which were designated as the fourth sub-example specimen 141. The above-mentioned aluminum plate was also cut to prepare two rectangular test pieces in plan view, each 25 mm wide and 100 mm long, which were designated as the fifth sub-example specimen 151. The above-mentioned aluminum plate was also cut to prepare two rectangular test pieces in plan view, each 50 mm wide and 100 mm long, which were designated as the sixth sub-example specimen 161.

[0057] Then, the fourth to sixth working pieces 140 to 160 were each produced by the method indicated by reference numeral 1302 in FIG. 13. Specifically, a nylon hot melt sheet 200 was sandwiched between a short end portion (longitudinal length 5 mm) of one fourth sub-working piece 141 and a short end portion (longitudinal length 5 mm) of the other fourth sub-working piece 141. The two fourth sub-working pieces 141 in this state were then placed on a hot plate 400 using two backing plates 300 and heated until the surface temperature of the sandwiched portion of the hot melt sheet 200 reached 150°C. The hot melt sheet 200 had a thickness of 0.2 mm.

[0058] After the surface temperature reaches 150°C, the pressure applied to the area sandwiching the hot melt sheet 200 is approximately 1 kgf / cm 2 A weight was placed on the hot melt sheet 200 and maintained in this state for one minute. The weight had been preheated to a surface temperature of approximately 150°C. After one minute had passed, the weight was removed and the hot melt sheet 200 was allowed to cool until the surface temperature of the sandwiched portion reached 60°C, thereby producing a fourth example specimen 140 as shown by reference numeral 1301 in FIG. 13. A fifth example specimen 150 and a sixth example specimen 160 were also produced in the same manner.

[0059] Additionally, comparative specimens 4 to 6 were prepared in the same manner as described above using an aluminum plate made of the same material as the aluminum particles constituting the untreated filler. The fourth comparative specimen had the same shape, structure, and size as the fourth example specimen 140, and corresponds to a test specimen according to a fourth comparative example of the present invention. The fifth comparative specimen had the same shape, structure, and size as the fifth example specimen 150, and corresponds to a test specimen according to a fifth comparative example of the present invention. The sixth comparative specimen had the same shape, structure, and size as the sixth example specimen 160, and corresponds to a test specimen according to a sixth comparative example of the present invention.

[0060] Tensile tests were performed on each of the fourth to sixth experimental specimens 140 to 160 and the fourth to sixth comparative specimens using a commercially available tensile tester. The tensile tests were performed under conditions of a chuck distance of 100 mm and a tensile speed of 0.5 mm / min (see reference numeral 1301 in FIG. 13). By performing these tensile tests, the mechanical properties (specifically, tensile shear stress) at the interface between the filler and resin 2 were evaluated for each of the fourth to sixth experimental specimens 140 to 160. Similarly, the mechanical properties (specifically, tensile shear stress) at the interface between the untreated filler and resin 2 were evaluated for each of the fourth to sixth comparative specimens.

[0061] The average Feret pore size for each of the fourth example piece 140 to the sixth example piece 160 was calculated by the following method. That is, using a commercially available SEM, images of the fourth example piece 140 to the sixth example piece 160 were generated. Then, for each image, an arbitrary location was selected from the surface of the imaged example piece, and then 100 were arbitrarily selected from the openings of the multiple holes formed at that arbitrary location. Then, for each of the selected 100 openings, the maximum Feret pore size and the minimum Feret pore size were measured to calculate the Feret pore size, and the obtained 100 Feret pore sizes were averaged to obtain the average Feret pore size.

[0062] The relationship between the average Feret pore size and the tensile shear stress for each of the fourth example specimen 140 to the sixth example specimen 160 and the fourth to sixth comparative specimens is shown in Figure 14. The graph shown in Figure 14 includes the results for the fourth example specimen 140 to the sixth example specimen 160 and the fourth to sixth comparative specimens. The same is true for Figure 15.

[0063] Specifically, the tensile shear stresses of the fourth to sixth comparative specimens were all constant at 7.6 MPa, partly because there were no pores in the first place. On the other hand, for the fourth to sixth comparative specimens 140 to 160, the tensile shear stresses corresponding to the respective average Feret pore diameters were all approximately 1.8 times or more of the constant value of 7.6 MPa. In other words, for each of the fourth to sixth comparative specimens 140 to 160, the tensile shear stress was significantly improved compared to the respective comparative specimens within the range of the average Feret pore diameter from the lower limit of 33 nm to the upper limit of 57 nm.

[0064] The approximate curve in the graph shown in FIG. 14 is expressed by the following formula (1). Y=-0.030X1 2 +2.7X1-45···(1) Y: Tensile shear stress [MPa] X1: Average Feret pore diameter [nm] (33≦X1≦57) The number of unit holes was calculated for each of the fourth to sixth example pieces 140 to 160 using the following method. That is, images of the fourth to sixth example pieces 140 to 160 were generated using a commercially available SEM, and then one arbitrary location was selected from the surface of the example piece for each image. The total number of holes formed at that arbitrary location was then counted and divided by the area of ​​the region captured in the image of that arbitrary location to calculate the number of unit holes.

[0065] The relationship between the number of unit holes and the tensile shear stress in each of the fourth to sixth example specimens 140 to 160 and the fourth to sixth comparative specimens is shown in Figure 15. Specifically, the tensile shear stress of each of the fourth to sixth comparative specimens was a constant value of 7.6 MPa for the reasons mentioned above. On the other hand, for the fourth to sixth example specimens 140 to 160, the tensile shear stress corresponding to each number of unit holes was all approximately 1.7 times or more of the constant value of 7.6 MPa. In other words, for each of the fourth to sixth example specimens 140 to 160, the number of unit holes was below the lower limit of 65 / µm. 2 to an upper limit of 163 particles / μm 2 Within the range of 1000 to 10000, the tensile shear stress was significantly improved compared to the comparative specimens.

[0066] The approximate curve in the graph shown in FIG. 15 is expressed by the following formula (2). Y=-0.00080X2 2 +0.12X2+14···(2) Y: Tensile shear stress [MPa] X2: Unit number of holes [pcs / μm 2 ](65≦X2≦163) Furthermore, from the results shown in Figures 14 and 15, by performing multiple regression analysis with the average Feret pore diameter X1 and the number of unit pores X2 as explanatory variables and the tensile shear stress Y as the objective variable, it was found that the following equation (3) holds. Y=-0.0050X1 2 -0.00091X2 2 +0.0033X1·X2+22···(3) Y: Tensile shear stress [MPa] X1: Average Feret pore diameter [nm] (33≦X1≦57) X2: Unit number of holes [pcs / μm 2 ](65≦X2≦163) [Explanation of symbols]

[0067] 1. Filler 10 Filler particles 11 Aluminum particles 12 Alumina coating 14 holes 16 Opening 100 Resin composition

Claims

1. A resin composition containing a filler consisting of a plurality of filler particles, Each of the plurality of filler particles is Aluminum particles, an alumina coating having a plurality of pores formed therein and covering the surfaces of the aluminum particles; the average value of the following (I) values ​​of the openings of the plurality of holes is 33 nm or more and 57 nm or less, Surface 1 μm of the alumina coating ２ The resin composition according to claim 1, wherein the number of holes per unit area is 65 or more and 163 or less. (Maximum Feret diameter + Minimum Feret diameter) ÷ 2 ... (I)

2. 2. The resin composition according to claim 1, wherein the relationship between the average value of (I) for the openings of each of the plurality of holes and the tensile shear stress generated at the interface between the filler and the substrate is expressed by the following formula (II): Y=-0.030X １ ２ +2.7X １ -45・・・(II) Y: Tensile shear stress [MPa] X １ :Average pore size [nm] (33≦X １ ≦57)

3. The resin composition according to claim 1 , wherein an average value of the perimeters of the openings of the plurality of holes is 103 nm or more and 186 nm or less.

4. The resin composition according to claim 1, wherein an average value of the following (IV) values ​​of the openings of the plurality of holes is 7 nm or more and 11 nm or less: Area ÷ Perimeter (IV)

5. The resin composition according to claim 1 , which is used for shielding electromagnetic waves.

6. The resin composition according to claim 5 , wherein the filler content is 3% by volume or more.

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