Resin molded body

Abstract

To provide a resin molded article equipped with AlN whiskers that have excellent thermal conductivity. [Solution] The resin molded body comprises at least a fibrous AlN single crystal, an oxygen-containing layer covering the surface of the AlN single crystal, AlN whiskers having a diameter in the range of 1.0 μm to 10 μm, and a resin material, wherein the weight ratio of the AlN whiskers is 3.0 wt% to 65.0 wt%. The number of contact points, which is the total number of points where the AlN whiskers contact each other per unit volume, is 0.015 / μm 3 More than 1 / μm 3 The following ranges apply, and the number of contact points is 0.016 / μm 3 More than 1 / μm 3 It is preferable that the range be as follows:

Description

[Technical Field]

[0001] This disclosure relates to a resin molded article comprising AlN whiskers. [Background technology]

[0002] As electronic devices become smaller and more powerful, the importance of thermal management in these devices is increasing. Due to concerns about performance degradation, heat must be dissipated to the outside of the device as much as possible. In this regard, improving the thermal conductivity of resin components used inside electronic devices is required.

[0003] Adding insulating fillers, such as spherical ceramics, is a known method for improving the thermal conductivity of resin parts. To improve thermal conductivity, it is important to increase the contact efficiency between fillers to form a network (heat dissipation path). When spherical fillers are used, it is common practice to fill (add) the resin material with spherical fillers at a weight ratio of 70 wt% to 90 wt% from the standpoint of network formation. However, high filling amounts (weight ratios) present problems such as increased weight of the resin material (resin parts) and reduced processability. Furthermore, the amount of filler that can be added to the resin material is practically reaching its limit.

[0004] In light of this background, some of the inventors of the present invention have researched and developed fibrous AlN whiskers that possess both high thermal conductivity and high insulating properties (Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-73951 [Patent Document 2] Japanese Patent Publication No. 2018-154534 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, from the viewpoints of thermal conductivity, workability, etc. for commercial use of AlN whiskers disclosed in Patent Document 1 and Patent Document 2 with respect to a resin material, it was still unclear how much should be filled and in what form the AlN whiskers should be added to the resin material. Therefore, the present disclosure aims to provide a resin molded body including AlN whiskers excellent in thermal conductivity according to various embodiments.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the inventors have found that even a resin molded body including AlN whiskers with a small filling amount (small weight ratio) contributes to an improvement in thermal conductivity.

[0008] That is, a resin molded body according to one aspect has a fibrous AlN single crystal and an oxygen-containing layer covering the surface of the AlN single crystal, and includes at least an AlN whisker having a diameter in the range of 1.0 μm or more and 10 μm or less and a resin material, and the weight ratio of the AlN whisker is 3.0 wt% or more and 65.0 wt% or less.

[0009] Further, in the resin molded body according to one aspect, the weight ratio of the AlN whisker is 3.0 wt% or more and 20.0 wt% or less, or 50.0 wt% or more and 65.0 wt% or less.

[0010] Further, in the resin molded body according to one aspect, the number of contact points, which is the total number of points where the AlN whiskers contact each other per unit volume, is 0.015 / μm 3 or more and 1 / μm 3 or less, and the number of contact points is 0.016 / μm 3 or more and 1 / μm 3 or less.

[0011] Further, in the resin molded body according to one aspect, the number of contact points, which is the total number of points where the AlN whiskers contact each other per unit volume, is 0.015 / μm 3Above 1 / μm 3 is in the following range, and the number of contact points where the AlN whiskers contact each other per unit volume is 0.020 / μm 3 Above 1 / μm 3 is in the following range.

[0012] Further, in the resin molded body according to one aspect, the number of contact points, which is the total number of points where the AlN whiskers contact each other per unit volume, is 0.015 / μm 3 Above 1 / μm 3 is in the following range, and the number of contact points is 0.023 / μm 3 Above 1 / μm 3 is in the following range.

[0013] Further, in the resin molded body according to one aspect, the AlN whiskers have a diameter in the range of 5.0 μm or more and 10 μm or less.

Advantages of the Invention

[0014] The resin molded body of the present disclosure is excellent in thermal conductivity while containing AlN whiskers at a low weight ratio.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram schematically showing the configuration of a resin molded body according to one embodiment. [Figure 2] It is a schematic diagram schematically showing the configuration of a resin molded body according to a first modification. [Figure 3] It is a schematic diagram schematically showing the configuration of a resin molded body according to a second modification. [Figure 4] It is a schematic diagram schematically showing the configuration of a resin molded body according to a third modification. [Figure 5] It is a diagram showing the results of the thermal conductivity of the resin molded bodies according to Examples and Comparative Examples. [Figure 6] It is a diagram showing the results of the thermal conductivity of the resin molded bodies according to Examples and Comparative Examples. [Figure 7]Figure 7 is a table showing the measurement results for each of the six samples of resin molded articles (Figure 1) according to the above-described embodiment and the seven samples of resin molded articles (Figure 4) according to the third modified example described above. [Figure 8] Figure 8 is a graph showing the relationship between the number of contact points and thermal conductivity for each of the resin molded articles according to one embodiment and the third modified example, based on the measurement results shown in Figure 7. [Figure 9] Figure 9 is a graph showing the relationship between the number of contact points and thermal conductivity for each of the four average diameters (ranges), based on the measurement results shown in Figure 7. [Modes for carrying out the invention]

[0016] Various embodiments of resin molded articles and their manufacturing methods will be described below with reference to the attached drawings. Note that common components in the drawings are denoted by the same reference numerals. Also, please note that the attached drawings are not necessarily drawn to an exact scale.

[0017] 1. Resin molded body according to one embodiment An overview of a resin molded article according to one embodiment will be described with reference to Figure 1. Figure 1 is a schematic diagram showing the configuration of a resin molded article 1 according to one embodiment. In this disclosure, "resin molded article" refers to a molded article formed mainly from AlN whiskers and resin material.

[0018] One embodiment of the resin molded body 1 mainly comprises a sheet-like structure 10 formed by a network of multiple (numerous) AlN whiskers 11 in contact with each other, and a resin material 20. The resin molded body 1 according to one embodiment (and the resin molded body according to the modified example described later) may contain other additives such as a dispersant. The network-formed sheet-like structure 10 refers to a thin sheet-like structure in which multiple (numerous) AlN whiskers 11 are intertwined and in contact with each other, thereby forming a large number of heat dissipation paths. The resin molded body 1 according to one embodiment is formed by impregnating this sheet-like structure 10 with the resin material 20.

[0019] Each of the multiple AlN whiskers 11 mainly comprises a fibrous AlN single crystal and an oxygen-containing layer that covers the surface of the AlN single crystal in a cylindrical shape. Furthermore, each of the multiple AlN whiskers 11 may also include a hydrophobic layer that covers the oxygen-containing layer in a cylindrical shape on the outside of the oxygen-containing layer.

[0020] The length of each of the multiple AlN whiskers 11 may be in the range of 1.0 μm to 5.0 cm, but is not limited to this range. The diameter of each of the multiple AlN whiskers 11 may be in the range of 0.1 μm to 50.0 μm, but from the viewpoint of network formation (formation of heat dissipation paths), the diameter of the AlN whiskers 11 used in the resin molded body 1 is preferably 1.0 μm or more, and more preferably 2.0 μm to 50.0 μm. Since the details of the structure and manufacturing method of the AlN whiskers 11 used in the resin molded body 1 are already known (see, for example, Patent Documents 1 and 2 above), a detailed explanation of these is omitted in this disclosure.

[0021] Here, we will describe the manufacturing method for the sheet-like formed product 10 and the resin molded body 1 according to one embodiment.

[0022] First, multiple (many) AlN whiskers 11 manufactured by a known method are prepared. Then, the multiple AlN whiskers 11 are dispersed in a predetermined solvent, and a papermaking process is performed to produce a paper-like intermediate product in which the multiple AlN whiskers 11 are dispersed to a certain extent uniformly. Subsequently, this intermediate product can be pressed in a press machine at a predetermined pressure for a predetermined time to form a sheet-like product 10. The predetermined solvent can be any solvent without limitation, such as water or an organic solvent. When using an organic solvent as the predetermined solvent, for example, polar solvents such as ethanol or propanol can be used. The predetermined pressure is, for example, 10 kg / cm². 2 ~100kg / cm 2 The pressure should be such that [a certain pressure is appropriate]. The predetermined time mentioned above can be, for example, 5 to 60 minutes. The purpose of pressing the intermediate product with a press is to remove the predetermined solvent contained in the intermediate product. Therefore, if the content of the predetermined solvent in the intermediate product is small, the step of pressing the intermediate product with a press may be omitted, and the intermediate product produced as described above may be used as the sheet-like product 10.

[0023] Next, the formed sheet-like material 10 is placed on a predetermined mold, and after impregnating the mold with liquid resin material 20, the resin material 20 is solidified (hardened) to form a resin molded body 1 according to one embodiment.

[0024] Here, the resin material 20 can be any thermosetting resin without limitation, such as silicone resin, epoxy resin, phenolic resin, melamine resin, urea resin, thermosetting polyimide, unsaturated polyester resin, or polyurethane.

[0025] Furthermore, as the resin material 20, thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, acrylonitrile styrene copolymer, acrylonitrile butadiene styrene copolymer, acrylonitrile ethylene propylene diene styrene copolymer, and methacrylic resin can be used without limitation.

[0026] Furthermore, as the resin material 20, fluororesins such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride can be used without limitation.

[0027] Furthermore, as the resin material 20, polycarbonate, polyamide resin, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polyether ether ketone, polyphenyl sulfide, polysulfone, polyetherimide, polyamideimide, thermoplastic polyimide, liquid crystal polymer, etc., can be used without limitation.

[0028] Furthermore, as the resin material 20, acrylonitrile styrene acrylate, atactic polypropylene, cellulose acetate, cellulose acetate butyrate, chlorinated vinyl chloride, chloroprene rubber, diallyl phthalate, ethylene ethyl acrylate, ethylene propylene diene terpolymer, ethylene tetrafluoroethylene copolymer, ethylene vinyl acetate copolymer, ethyl vinyl ether, ethylene vinyl alcohol copolymer, perfluororub, tetrafluoroethylene-hexafluoropropylene copolymer, flexible urethane foam, etc., can be used without limitation.

[0029] Furthermore, as the resin material 20, glass fiber reinforced plastics, glass fiber reinforced thermoplastics, butyl rubber, ionomers, isoprene rubber, melamine formaldehyde, methyl methacrylate, nitrile rubber, natural rubber, polyacrylic acid, polyallyl ether ketone, polyester alkyd resin, polyacrylonitrile, polyarylate, etc., can be used without limitation.

[0030] Furthermore, as the resin material 20, poly(p-phenylenebenzobisoxazole), polybutadiene styrene, diallyl terephthalate, polydicyclopentadiene, polyethylene naphthalate, polyethylene oxide, polyethersulfone, phenol formaldehyde, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, polyisobutylene, polymethylpentene, etc., can be used without limitation.

[0031] Furthermore, as the resin material 20, polyphthalamide, polyphenylene ether, polyphenylene oxide, polytrimethylene terephthalate, reactive polyurethane, polyvinyl alcohol, polyvinyl butyral, acrylic-modified polyvinyl chloride, polyvinyl dichloride, vinyl chloride vinyl acetate copolymer, etc., can be used without limitation.

[0032] Furthermore, as the resin material 20, polyvinyl formal, polyvinylpyrrolidone, styrene-butadiene, styrene-butadiene rubber, styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene block copolymer, styrene-isoprene-styrene block copolymer, sheet molding compound, syndiotactic polystyrene, thermoplastic elastomer, thermoplastic polyurethane, urea-formaldehyde resin, ultra-high molecular weight polyethylene, vinyl chloride ethylene, vinyl chloride octyl acrylate, crosslinked polyethylene, etc., can also be used without limitation.

[0033] In one embodiment, the amount of AlN whiskers 11 (multiple AlN whiskers 11) in the resin molded body 1 is preferably in the range of 3.0 wt% to 65.0 wt% by weight, from the viewpoint of thermal conductivity and processability of the resin molded body 1. In order to improve the thermal conductivity of the resin molded body 1, it is necessary to fill the resin molded body 1 with at least 3.0 wt% of AlN whiskers 11. Furthermore, if the weight ratio of AlN whiskers 11 in the resin molded body 1 becomes 65.0 wt% or more, and especially 70.0 wt% or more, the processability of the resin molded body 1 will decrease (it will become difficult to mold the resin molded body 1). When a resin molded body 1 with important processability is required, the amount of AlN whiskers 11 (multiple AlN whiskers 11) in the resin molded body 1 is more preferably in the range of 3.0 wt% to 20.0 wt% by weight, and most preferably in the range of 5.0 wt% to 20.0 wt%. On the other hand, when a resin molded body 1 with high thermal conductivity is required, the amount of AlN whiskers 11 (multiple AlN whiskers 11) filling in the resin molded body 1 is more preferably in the range of 40.0 wt% to 65.0 wt% by weight, and most preferably in the range of 50.0 wt% to 65.0 wt%.

[0034] 2. Resin molded body according to the modified example 2-1. First variation Next, the outline of the resin molded body according to the first modified example will be explained with reference to Figure 2. Figure 2 is a schematic diagram showing the configuration of the resin molded body 2 according to the first modified example.

[0035] The resin molded body 2 according to the first modified example mainly comprises a plurality of AlN whiskers 11, the resin material 20 described above, and spherical AlN fillers 30. In other words, the resin molded body 2 according to the first modified example can be understood as a conventional resin material mainly comprising the resin material 20 and spherical AlN fillers 30, with a plurality of AlN whiskers 11 further added.

[0036] Furthermore, in the resin molded body 2 according to the first modified example, the sheet-like material 10 included in the resin molded body 1 according to the first embodiment described above does not exist. In other words, the resin molded body 2 according to the first modified example is formed by first preparing a plurality (many) of AlN whiskers 11 manufactured by a known method and a plurality of spherical AlN fillers 30 manufactured by a known method, placing them uniformly dispersed in a predetermined mold, impregnating the mold with a liquid resin material 20, and then solidifying (curing) the resin material 20.

[0037] The multiple AlN whiskers 11 and resin material 20 contained in the resin molded body 2 according to the first modified example can be the same as those used in the resin molded body 1 according to one embodiment. In addition, the spherical AlN filler 30 contained in the resin molded body 2 according to the first modified example can be a generally known type.

[0038] In the resin molded body 2 according to the first modified example, the amount of AlN whiskers 11 (multiple AlN whiskers 11) filling is preferably in the range of 3.0 wt% to 20.0 wt% by weight, more preferably in the range of 5.0 wt% to 20.0 wt%, and most preferably in the range of 5.0 wt% to 10.0 wt%, when the amount of spherical AlN filler 30 filling in the resin molded body 2 is, for example, about 60 wt% to 70 wt% by weight. If the spherical AlN filler 30 is already present in an amount of about 60 wt% to 70 wt%, then including 3.0 wt% or more of AlN whiskers 11 by weight makes it possible to improve the thermal conductivity of the resin molded body 2. On the other hand, if the spherical AlN filler 30 is already present in an amount of about 60 wt% to 70 wt%, then including more than 20.0 wt% of AlN whiskers 11 by weight is undesirable from the viewpoint of processability and moldability of the resin molded body 2.

[0039] 2-2. Second variation Next, an overview of the resin molded body according to the second modified example will be described with reference to Figure 3. Figure 3 is a schematic diagram showing the configuration of the resin molded body 3 according to the second modified example.

[0040] The resin molded body 3 according to the second modified example mainly comprises a plurality (many) of AlN whiskers 11 and a spherical resin material 50. In the resin molded body 3 according to the second modified example, as shown in Figure 3, a coated product 40 is formed in which each surface of the plurality of resin materials 50 is covered with a plurality of AlN whiskers 11. In other words, the resin molded body 3 according to the second modified example includes the coated product 40 as a substitute for the sheet-like product 10 in the resin molded body 1 according to one embodiment.

[0041] The resin molded body 3 according to the second modified example is formed by first preparing a plurality (many) of AlN whiskers 11 and a plurality of spherical resin materials 50 manufactured by a known method, forming a coated product 40 in which the surface of each of the plurality of resin materials 50 is covered with the plurality of AlN whiskers 11, then placing the coated product 40 on a predetermined mold, pressing the coated product 40 with a predetermined pressure and heat-treating it at a predetermined temperature.

[0042] The multiple AlN whiskers 11 included in the resin molded body 3 according to the second modified example can be the same as those used in the resin molded body 1 according to one embodiment. Furthermore, the resin material 50 included in the resin molded body 3 according to the second modified example can be the same as the resin material 20 that can be used in the resin molded body 1 according to one embodiment, and can be spherical without limitation.

[0043] Furthermore, as the second resin material 50 in the resin molded body 3 according to the second modification, a material with a diameter of 1.0 μm to 200.0 μm can be used as an example, more preferably a material with a diameter of 5.0 μm to 100.0 μm can be used, and most preferably a material with a diameter of 10.0 μm to 50.0 μm can be used.

[0044] The amount of AlN whiskers 11 (multiple AlN whiskers 11) filling in the resin molded body 3 according to the second modified example is preferably in the range of 3.0 wt% to 65.0 wt% by weight, from the viewpoint of thermal conductivity and processability of the resin molded body 3, as in the first embodiment described above.

[0045] 2-3. Third Variation Next, an overview of the resin molded body according to the third modified example will be described with reference to Figure 4. Figure 4 is a schematic diagram showing the structure of the resin molded body 4 according to the third modified example.

[0046] The resin molded body 4 according to the third modified example mainly comprises a plurality (many) of AlN whiskers 11 and the resin material 20 described above. The resin molded body 4 according to the third modified example is similar to the resin molded body 1 according to the first embodiment described above, but instead of using the sheet-like formed material 10 in the resin molded body 1, it uses multiple (many) AlN whiskers 11 that have been crushed to shorten their length. The length of the plurality (many) AlN whiskers 11 in the resin molded body 4 according to the third modified example is generally in the range of 1.0 μm to 300.0 μm, but is not limited to this range, and may be shorter than the length of the AlN whiskers used in the resin molded body 1 according to the first embodiment.

[0047] The resin molded body 4 according to the third modified example is formed by first preparing a plurality (many) of AlN whiskers 11 manufactured by a known method, crushing them to a predetermined length, dispersing the crushed plurality (many) of AlN whiskers 11 in a liquid resin material 20, placing the liquid resin material 20 in which the plurality (many) of AlN whiskers 11 are dispersed in a predetermined mold, and then solidifying (curing) the resin material 20.

[0048] The multiple AlN whiskers 11 and resin material 20 included in the resin molded body 4 according to the third modified example can be the same as those used in the resin molded body 1 according to one embodiment.

[0049] The amount of AlN whiskers 11 (multiple AlN whiskers 11) filling in the resin molded body 4 according to the third modified example is preferably in the range of 3.0 wt% to 65.0 wt% by weight, and more preferably in the range of 20.0 wt% to 40.0 wt%, from the viewpoint of thermal conductivity and processability of the resin molded body 4, as in the first embodiment described above. [Examples]

[0050] 1. Examples 1 to 3 After dispersing numerous AlN whiskers produced by a known method in water, a 10-minute straining process was performed to obtain a paper-like intermediate product in which multiple AlN whiskers were dispersed to a certain extent uniformly. Subsequently, the obtained intermediate product was processed at 40 kg / cm³. 2 A sheet-like material was formed by pressing it in a press machine at the specified pressure for 30 minutes.

[0051] Next, the formed sheet-like material was placed in a predetermined mold, and liquid epoxy resin was added to the mold. The epoxy resin was then cured by heating the mold at 80°C for 3 hours, followed by heating at 150°C for 1 hour, to obtain a resin molded body. The liquid epoxy resin was added so that the weight ratio (wt%) of AlN whiskers contained in the sheet-like material to the resin molded body was as shown in Table 1 below. The diameter of the AlN whiskers used in Example 1 was larger than the diameter of the AlN whiskers used in Examples 2 and 3. Furthermore, the resin molded bodies in Examples 1 to 3 correspond to the resin molded body 1 according to the above embodiment.

[0052] [Table 1]

[0053] 2. Examples 4 and 5 A slurry was prepared by adding and dispersing multiple spherical AlN fillers, manufactured by a known method, into a liquid epoxy resin, and then adding and dispersing a large number of AlN whiskers, also manufactured by a known method, into the epoxy resin. This slurry was uniformly placed in a predetermined mold, and the epoxy resin was cured by heating the mold at 80°C for 3 hours, followed by heating at 150°C for 1 hour, to obtain a resin molded body. The liquid epoxy resin was added so that the weight ratio (wt%) of AlN whiskers to the resin molded body was as shown in Table 2 below. The values ​​in parentheses in Table 2 below indicate the weight ratio of the total weight of AlN whiskers and spherical AlN fillers to the resin molded body. Furthermore, the resin molded bodies in Examples 4 and 5 correspond to resin molded body 2 of the first modified example described above.

[0054] [Table 2]

[0055] 3. Examples 6 and 7 A large number of AlN whiskers manufactured by a known method and a large number of spherical (powdered) phenolic resins were prepared. Then, a coated structure was formed such that the surface of each of the multiple phenolic resins was covered with multiple AlN whiskers.

[0056] Next, the formed coated object was placed on a predetermined mold, and the coated object was heated at 180°C for 5 minutes under pressure to cure the phenolic resin and obtain a resin molded body. The coated object was formed such that the weight ratio (wt%) of AlN whiskers contained in the resin molded body was as shown in Table 3 below. The resin molded bodies in Examples 6 and 7 correspond to resin molded body 3 in the second modified example described above.

[0057] [Table 3]

[0058] 4. Examples 8 to 11 Numerous AlN whiskers, manufactured by a known method, were crushed to a predetermined length. The lengths of the AlN whiskers ranged from 1.0 μm to 300.0 μm. Next, the crushed AlN whiskers were dispersed in a liquid epoxy resin. The liquid epoxy resin containing the dispersed AlN whiskers was placed in a predetermined mold, and the epoxy resin was cured by heating the mold at 80°C for 3 hours, followed by heating at 150°C for 1 hour, to obtain a resin molded body. The AlN whiskers were dispersed in the liquid epoxy resin such that the weight ratio (wt%) of the AlN whiskers contained in the resin molded body was as shown in Table 4 below. The diameter of the AlN whiskers used in Example 11 was greater than the diameter of the AlN whiskers used in Examples 8 to 10. Furthermore, the resin molded bodies according to Examples 8 to 11 correspond to the resin molded body 4 according to the third modified example described above.

[0059] [Table 4]

[0060] 5. Comparative Example 1 and Comparative Example 2 Comparative Examples 1 and 2 used commercially available resin molded articles containing only spherical AlN fillers. The resin material used in these commercially available products was silicone resin. The amount of spherical AlN filler contained in each of the resin molded articles of Comparative Example 1 and Comparative Example 2 (weight ratio (wt%) to the resin molded article) is shown in Table 5 below.

[0061] [Table 5]

[0062] 6. Evaluation The thermal conductivity of each of the resin molded articles obtained as described above, from Example 1 to Example 11, and from Comparative Example 1 and Comparative Example 2, was measured. The thermal conductivity of Example 1 to Example 11, and from Comparative Example 1 and Comparative Example 2, was calculated from the product of thermal diffusivity, specific heat, and density. For Example 1 to Example 11, and from Comparative Example 1 and Comparative Example 2, a LaserPIT device manufactured by Advance Riko Co., Ltd. was used to measure the thermal diffusivity, a DSC-60A manufactured by Shimadzu Corporation was used to measure the specific heat, and an AD-1653 manufactured by A&D Corporation was used to measure the density. Figures 5 and 6 show the results of the thermal conductivity of the resin molded articles from Example 1 to Example 11, and from Comparative Example 1 and Comparative Example 2.

[0063] As shown in Figures 5 and 6, the resin molded articles according to Examples 1 to 11 exhibited excellent thermal conductivity while containing AlN whiskers in a small weight ratio. Furthermore, comparing Example 5 with Comparative Example 1 (Example 5 can be understood as Comparative Example 1 with an additional 5.0 wt% of AlN whiskers added), the thermal conductivity of Example 5 was higher than that of Comparative Example 1. Moreover, the thermal conductivity of the resin molded articles according to Examples 1 to 3 was higher than that of the other examples.

[0064] The above results suggest that in the resin molded articles according to Examples 1 to 11, the network (heat dissipation path) caused by AlN whiskers is efficiently formed. In particular, it is thought that such a network is formed even more efficiently in resin molded articles that include sheet-like structures.

[0065] 7. Experimental Data Figure 7 is a table showing the measurement results for each of the six samples of resin molded body 1 (Figure 1) according to the above-described embodiment and the seven samples of resin molded body 4 (Figure 4) according to the third modified example described above. In Figure 7, "filling amount (wt)" indicates the amount of AlN whiskers 11 filled into the resin molded body (unit: wt), "filling amount (vol%)" indicates the amount of AlN whiskers 11 filled into the resin molded body (unit: vol%), and "thermal conductivity" indicates the thermal conductivity of the resin molded body.

[0066] Furthermore, the "number of contact points per unit volume" (i.e., "number of contact points") is defined as the number of contact points between multiple AlN whiskers 11 filled in the resin molded body per unit volume (μm). 3 This indicates the total number of contact points per unit area. Here, as an example, the number of contact points of AlN whisker 11 in a volume of 500 (μm) × 500 (μm) × 500 (μm) was measured, and the number of contact points measured in this way was calculated as 500. 3 (μm 3 The number of contact points per unit volume (i.e., "contact points") is calculated by dividing by ). In this case, the number of contact points was measured by taking X-ray CT images of each sample and performing computer-based image analysis on the acquired X-ray CT images.

[0067] Furthermore, the diameters of the multiple AlN whiskers 11 filled in the resin molded body are not exactly the same but vary. The "average diameter (μm)" represents the average of the diameters of these multiple AlN whiskers 11 (= sum of the diameters of the multiple AlN whiskers / total number of AlN whiskers). Here, as an example of "multiple AlN whiskers" for determining the average diameter, a portion of each sample was imaged using an electron microscope, and all AlN whiskers contained in the image obtained from this imaging were used. In another example, the entire sample was imaged using an electron microscope, and all AlN whiskers contained in the image obtained from this imaging could be used as "multiple AlN whiskers." In yet another example, all AlN whiskers contained in a unit volume in an image obtained using any of the above methods could be used as "multiple AlN whiskers."

[0068] Figure 8 is a graph showing the relationship between the number of contact points and thermal conductivity for each of the resin molded body 1 according to one embodiment and the resin molded body 4 according to the third modified example, based on the measurement results shown in Figure 7.

[0069] As is clear from Figures 8 and 7, focusing on the resin molded body 4 according to the third modified example, the number of contact points is 0.012 ( / μm).3 When the number of contact points is 0.015 ( / μm), the thermal conductivity is 1.5 (W / mk), whereas when the number of contact points is 0.015 ( / μm). 3 When the temperature is such that the thermal conductivity increases to 2 (W / mk) (following a quadratic curve), the upper limit of the number of contact points is preferably 1.0. Specifically, if the number of contact points exceeds 1, the viscosity of the resin material increases, which may make it difficult to mold the resin molded body into a sheet. Therefore, the upper limit of the number of contact points is preferably 1.0.

[0070] Therefore, the number of contact points is 0.015 ( / μm). 3 ) or more 1.0( / μm 3 It is even more preferable that the number of contact points be 0.029 ( / μm). Furthermore, as another upper limit, the number of contact points is 0.029 ( / μm). 3 When the number of contact points is 0.012 ( / μm), the thermal conductivity is 5 (W / mk), and this thermal conductivity is equal to the number of contact points. 3 The thermal conductivity is significantly greater than that of (1.5 (W / mk)) when ). Therefore, the number of contact points is 0.015 ( / μm 3 ) or more 0.029( / μm 3 It is even more preferable that the following conditions apply:

[0071] In addition, the number of contact points is 0.015 ( / μm). 3 When the number of contact points is 0.016 ( / μm), the thermal conductivity is 2 (W / mk), whereas the number of contact points is 0.016 ( / μm). 3 The thermal conductivity increases to 3 (W / mK) (following a quadratic curve) when ). Therefore, the number of contact points is 0.016 ( / μm). 3 ) or more 1.0( / μm 3 It is even more preferable that it be less than or equal to 0.016 ( / μm). 3 ) or more 0.029( / μm 3 It is even more preferable that the following conditions apply:

[0072] Focusing on a resin molded body 1 according to one embodiment, the number of contact points is 0.014 ( / μm). 3When the number of contact points is 0.020 ( / μm), the thermal conductivity is 4 (W / mk), whereas the number of contact points is 0.020 ( / μm). 3 The thermal conductivity increases to 4.7 (W / mk) when the temperature is such that... Furthermore, from a manufacturing standpoint (from the perspective of ensuring processability), it is preferable that the upper limit of the number of contact points be 1.0. Specifically, if the number of contact points exceeds 1.0, it may become difficult to form multiple AlN whiskers into a nonwoven fabric, and / or it may become difficult for the resin material to impregnate the voids formed between multiple AlN whiskers. Therefore, it is preferable that the upper limit of the number of contact points be 1.0.

[0073] Therefore, the number of contact points is 0.020 ( / μm). 3 ) or more 1.0( / μm 3 It is even more preferable that the number of contact points be 0.046 ( / μm) or less. Furthermore, as another upper limit, the number of contact points is 0.046 ( / μm). 3 When the number of contact points is 0.014 ( / μm), the thermal conductivity is 14 (W / mk), and this thermal conductivity is equal to the number of contact points. 3 The thermal conductivity is significantly greater than that of (4(W / mk)) when ). Therefore, the number of contact points is 0.020( / μm 3 ) or more 0.046( / μm 3 It is even more preferable that the following conditions apply:

[0074] In addition, the number of contact points is 0.020 ( / μm). 3 When the number of contact points is 0.023 ( / μm), the thermal conductivity is 4.7 (W / mk), whereas when the number of contact points is 0.023 ( / μm). 3 When the temperature is such that the thermal conductivity increases to 5.3 (W / mK) (following a quadratic curve), the number of contact points is 0.023 ( / μm). 3 ) or more 1.0( / μm 3 It is even more preferable that it be less than or equal to 0.023 ( / μm 3 ) or more 0.046( / μm 3 It is even more preferable that the following conditions apply:

[0075] Figure 9 is a graph showing the relationship between the number of contact points and thermal conductivity for each of the four average diameters (ranges), based on the measurement results shown in Figure 7. Here, the four average diameters (ranges) include the ranges of less than 1 μm, 1 μm or more and less than 5 μm, 5 μm or more and less than 10 μm, and 10 μm or more. Note that these four average diameters do not distinguish between the resin molded body 1 according to one embodiment and the resin molded body 4 according to the third modified example. Also, in the graph shown in Figure 9, the horizontal axis is expressed on a logarithmic scale.

[0076] As is clear from Figures 9 and 7, for the same or nearly the same number of contact points, the thermal conductivity is significantly higher when the average diameter is 1 μm or more and 10 μm or less compared to when the average diameter is less than 1 μm. Therefore, it is preferable that the average diameter is 1 μm or more and 10 μm or less. Furthermore, it is even more preferable that the average diameter is 5 μm or more and 10 μm or less.

[0077] This application is based on Japanese Patent Application No. 2022-016179, filed on February 4, 2022, entitled “Resin Molded Article and Method for Manufacturing the Same,” and enjoys the benefit of priority from that Japanese Patent Application. The entire contents of that Japanese Patent Application are incorporated herein by reference. [Explanation of symbols]

[0078] 1-4 Resin molded body 10 Sheet-like formed material 11 AlN Whisker 20 Resin materials 30 Spherical AlN fillers 40 Covered Formation 50 Spherical resin materials

Claims

1. A fibrous AlN single crystal, and an AlN whisker having a diameter in the range of 1.0 μm to 10 μm, having an oxygen-containing layer covering the surface of the AlN single crystal, Resin materials and, It must have at least the following: A resin molded article in which the weight ratio of the AlN whiskers is 3.0 wt% or more and 65.0 wt% or less.

2. The resin molded article according to claim 1, wherein the weight ratio of the AlN whiskers is 3.0 wt% or more and 20.0 wt% or less, or 50.0 wt% or more and 65.0 wt% or less.

3. The number of contact points, which is the total number of points where the AlN whiskers come into contact with each other per unit volume, is 0.015 / μm ３ More than 1 / μm ３ It is within the following range: The number of contact points is 0.016 / μm ３ More than 1 / μm ３ A resin molded article according to claim 1 or 2, within the following range.

4. The number of contact points, which is the total number of points where the AlN whiskers come into contact with each other per unit volume, is 0.015 / μm ３ More than 1 / μm ３ It is within the following range: The number of contact points is 0.020 / μm ３ More than 1 / μm ３ A resin molded article according to claim 1 or 2, within the following range.

5. The number of contact points, which is the total number of points where the AlN whiskers contact each other per unit volume, is 0.015 / μm ３ or more and 1 / μm ３ and is in the following range The number of contact points is 0.023 / μm ３ More than 1 / μm ３ A resin molded article according to claim 1 or 2, within the following range.

6. The resin molded article according to claim 1 or 2, wherein the AlN whisker has a diameter in the range of 5.0 μm to 10 μm.

Images