Urethane foam molded object and method for its manufacture

Abstract

Urethane foam molded object, comprising: a base material made from polyurethane foam; and Composite particles that are incorporated into and aligned within the base material, wherein the composite particles comprise thermally conductive particles formed from a non-magnetic material and having a thermal conductivity of 200 W / m · K or higher, and magnetic particles attached to surfaces of the thermally conductive particles with a binder and surface-treated with one or more surfactant(s) selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, wherein the heat-conducting particles comprise at least one of graphite particles and expandable graphite particles, and wherein the magnetic particles include at least one iron particle and one stainless steel particle.

Description

[Technical field]

[0001] The present disclosure relates to a urethane foam molded article with high thermal conductivity and a method for its production. [State of the art]

[0002] Urethane foam molded parts are used in various fields, such as motor vehicles and electronic devices, as sound-absorbing or vibration-damping materials. Urethane foam molded parts have a number of cells (bubbles) inside and consequently exhibit low thermal conductivity and poor heat dissipation properties. Therefore, in a case where a urethane foam molded part is arranged around a machine, motor, or the like that generates heat, there is concern that heat may accumulate in the urethane foam molded part and the temperature may rise. To solve this problem, for example, as described in patent document 1, a urethane foam molded part with heat dissipation properties was developed by arranging particles with high thermal conductivity, such as...Graphite is used to align the polyurethane foam and form a heat transfer path in the direction of alignment. Furthermore, patent document 2 discloses an elastomer molded article comprising an elastomer substrate and a powder of composite particles contained in and aligned within the substrate, wherein the composite particles comprise thermally conductive particles made of a non-magnetic material and magnetic particles bonded to the surfaces of the thermally conductive particles by a binder, and wherein the particle size distribution of the composite particle powder has two peaks, one peak on the side of the small particle size and one peak on the side of the large particle size. [Document List][Patent Documents] Patent Document 1: JP 2011-225833 A Patent Document 2: JP 2015-30735 A [Summary of the invention][Technical problem]

[0003] In the urethane foam molded article described in patent document 1, composite particles are used to align the particles with high thermal conductivity (heat-conducting particles). These composite particles are obtained by granulating the particles after magnetic particles have been attached to their surfaces. Furthermore, the composite particles are mixed with a foam urethane resin starting material and foam-molded in a magnetic field, thus producing a urethane foam molded article with the aligned composite particles. If the structure or size of the particles is not uniform when mixed with the foam urethane resin starting material, it becomes difficult to control the crosslinking and foaming reactions during foam molding.Furthermore, if there is a large mass difference between the particles to be mixed, the fluidity of the particles changes during foaming, the particles are not uniformly distributed in the foam urethane resin starting material, and the performance characteristics, such as heat dissipation properties, vary. In particular, when mixing the composite particles, their orientation plays a role in the formation of the heat transfer path, and the state of the magnetic particles attached to the heat-conducting particles—i.e., the particle size distribution of the composite particles—becomes important. However, in the prior art, there has been insufficient research on the particle size distribution of composite particles, and therefore concerns exist that the heat dissipation properties and formability of urethane foam molded parts may become inconsistent.

[0004] The present disclosure was obtained taking such circumstances into account, and one object of the present disclosure is to provide a urethane foam molded article in which the grain size of the admixed composite particles is advantageous and the thermal conductivity and formability are excellent. Furthermore, it is another object of the present disclosure to provide a method for its production. [Solution to the problem]

[0005] (1) To solve the problem described above, a urethane foam molded article of the present disclosure comprises a base material made of polyurethane foam and composite particles incorporated into and aligned within the base material, wherein the composite particles comprise thermally conductive particles formed of a non-magnetic material having a thermal conductivity of 200 W / m·K or higher, and magnetic particles attached to the surfaces of the thermally conductive particles with a binder and surface-treated with one or more surfactant(s) selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, wherein the thermally conductive particles comprise at least one of graphite particles and expandable graphite particles.and wherein the magnetic particles comprise at least one of iron particles and one of stainless steel particles.

[0006] The composite particles incorporated into the urethane foam molded article of the present disclosure are surface-treated with a predetermined surfactant. This allows the magnetic particles to be easily attached to the thermally conductive particles. Most of the magnetic particles exhibit poor hydrophilicity. Therefore, when a binder was added along with water at the time of composite particle production, it was difficult for the magnetic particles to attach to the thermally conductive particles. Consequently, it was not possible to produce the desired composite particles, and there were concerns that magnetic particles might remain after granulation that were not attached to the thermally conductive particles.Therefore, as a result of repeated investigations by the present inventors, it was found that the combined use of a binder and a surfactant during granulation improves the adhesion properties of the magnetic particles to the heat-conducting particles. A urethane foam molded article is produced by mixing the granulated composite particles with a foam urethane resin starting material and foaming the mixture in a magnetic field. Therefore, there is a need to select a surfactant that is less likely to interfere with the crosslinking and foaming reactions during foaming than the surfactant used during granulation.Based on this point, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant are used in the urethane foam molding article of the present disclosure. The carboxylic acid-type and the succinic acid-type surfactants are weakly acidic surfactants and have a minimal influence on the crosslinking and foaming reactions of the foam urethane resin starting material. Therefore, the use of the surfactant enables the production of composite particles in which a desired amount of magnetic particles has been attached to the surfaces of the thermally conductive particles, and allows the production of a urethane foam molding article without impairing the foaming process.Additionally, the surface treatment of the composite particles prevents the formation of rust in the composite particles.

[0007] According to the urethane foam molding device of the present disclosure, high thermal conductivity can be achieved because the orientation of the composite particles is advantageous and a heat transfer path is formed by the interconnected composite particles. Furthermore, since the inuniformity in the structure or size of the composite particles is reduced, it is easy to control the crosslinking and foaming reactions during foam molding, and the formability is excellent. Moreover, since the dispersibility of the composite particles is also advantageous, it is less likely that the performance, such as the heat dissipation properties, will vary depending on the position.

[0008] (2) In the configuration described above, a succinic acid-type surfactant can be included as the surfactant. A succinic acid-type surfactant not only has a low impact on foaming but also exhibits excellent rust-inhibiting properties. Therefore, even when a material prone to rusting, such as iron, is used as the magnetic particles, the formation of rust during granulation using water or similar processes can be prevented. According to the present configuration, manufacturing costs can be reduced because a relatively inexpensive material, such as iron, can be used as the magnetic particles.

[0009] (3) In each of the configurations described above, the surfactant can be water-soluble. Since, according to the present configuration, it is possible to dissolve and add the surfactant to the water during the granulation of the composite particles, the surface treatment can be carried out easily.

[0010] (4) In each of the configurations described above, in a particle size distribution of the composite particles, the proportion of small particles with a particle diameter of 100 µm or less may be 10% by mass or less in a case where the total mass of the composite particles is fixed at 100% by mass. As described below, since a number of particles with a particle diameter greater than 100 µm are included as the heat-conducting particles, small particles with a particle diameter of 100 µm or less become magnetic particles that do not constitute the composite particles or the like.In the present configuration, the proportion of magnetic particles not attached to the heat-conducting particles is small; in other words, the proportion of the composite particles, which have an advantageous grain size and include the magnetic particles attached to the surfaces of the heat-conducting particles, is large, which is effective in achieving high thermal conductivity and very good formability.

[0011] (5) In each of the configurations described above, the average particle diameter of the heat-conducting particles can be 200 µm or more and 2000 µm or less. According to the present configuration, such an average particle diameter is advantageous for forming a heat transfer path and the dispersibility of the composite particles can also be ensured.

[0012] (6) In each of the configurations described above, the magnetic particles can contain iron particles. Since iron is relatively inexpensive, the manufacturing costs can be reduced according to the present configuration. In addition, the composite particles are surface-treated with a surfactant. The surfactant has a corrosion-inhibiting effect, thus preventing the iron particles from rusting.

[0013] (7) In each of the configurations described above, the composite particles may include insulating inorganic particles attached to the surfaces of the thermally conductive particles with a binder. The insulating inorganic particles may be attached directly to the surfaces of the thermally conductive particles or may be attached indirectly via the magnetic particles, i.e., attached to the surfaces of the magnetic particles attached to the thermally conductive particles. The magnetic particles are made of a ferromagnetic material, such as stainless steel or iron. Therefore, the composite particles with the magnetic particles attached to the surfaces of the thermally conductive particles are highly thermally conductive.Furthermore, when the insulating inorganic particles are attached to the surfaces of the thermally conductive particles, it is less likely that the thermally conductive or magnetic (electrically conductive) particles between adjacent composite particles will come into contact with each other, even if the composite particles are oriented in a state where they are in contact. Therefore, the electrical resistance between the composite particles becomes high. Moreover, the insulating inorganic particles bring the composite particles into contact with each other, which can interrupt the electrical conduction between them. As a result, electrical insulating properties can be achieved in the urethane foam molded article of the present disclosure.As described above, both high thermal conductivity and very good electrical insulation properties can be achieved according to the present configuration. Therefore, the urethane foam molded article of the present disclosure can be used in applications where both heat dissipation properties and electrical insulation properties are required, such as a heat dissipation element in electronic devices. Furthermore, it is more effective to combine the present configuration with all of configurations (2) to (6).

[0014] (8) A process for producing a urethane foam molded article of the present disclosure, which is an aspect of a process for producing a urethane foam molded article of the present disclosure, comprises a composite particle manufacturing step of producing composite particles by stirring a granulation starting material comprising a powder of thermally conductive particles made from a non-magnetic material having a thermal conductivity of 200 W / m·K or higher, a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water, wherein the thermally conductive particles comprise at least one of graphite particles and expandable graphite particles.and wherein the magnetic particles comprise at least one of iron particles and stainless steel particles, a mixed starting material manufacturing step of producing a mixed starting material by mixing a powder of the composite particles and a foam urethane resin starting material, and a foam forming step of casting the mixed starting material into a cavity of a foam forming tool and performing foam forming while a magnetic field is applied such that a magnetic flux density in the cavity becomes substantially uniform.

[0015] In the composite particle manufacturing step, a predefined surfactant is used to attach the magnetic particles to the surfaces of the thermally conductive particles with the binder. This allows the magnetic particles to be easily attached to the thermally conductive particles, enabling the production of desired composite particles with a relatively large number of magnetic particles attached. When a relatively large number of magnetic particles form the composite particles, an alignment of the composite particles can be achieved in a relatively weak magnetic field during the subsequent foaming step. Furthermore, the surfactant used is less likely to interfere with the foaming of the foam urethane resin starting material.As described above, according to the manufacturing process of the present disclosure, desired composite particles can be produced in which the magnetic particles are attached to the surfaces of the heat-conducting particles, and the urethane foam molded article of the present disclosure with high thermal conductivity can be easily produced without affecting the foam molding.

[0016] (9) The method for producing a urethane foam molded article of the present disclosure, which is an aspect of a method for producing a urethane foam molded article of the present disclosure having configuration (7), comprises a composite particle manufacturing step of producing composite particles, a mixed starting material manufacturing step of producing a mixed starting material by mixing a powder of the composite particles and a foam urethane resin starting material, and a foam forming step of casting the mixed starting material into a cavity of a foam forming tool and performing foam forming while a magnetic field is applied such that a magnetic flux density in the cavity becomes substantially uniform, wherein the composite particle manufacturing step comprises a first stirring step of stirring a first starting material, which is a powder of thermally conductive particles,which are made from a non-magnetic material and have a thermal conductivity of 200 W / m·K or higher, comprising a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water, wherein the thermally conductive particles comprise at least one of graphite particles and expandable graphite particles, and wherein the magnetic particles comprise at least one of iron particles and stainless steel particles, and comprising a second stirring step of adding and further stirring a powder of insulating inorganic particles to a stirred product of the first starting material. The following are cases,where the previous manufacturing process is referred to as the "first manufacturing process" and the present manufacturing process is referred to as the "second manufacturing process".

[0017] According to the second manufacturing process of the present disclosure, composite particles in which the insulating inorganic particles are arranged in the outermost layer can be easily produced. When the composite particles are used, the electrical resistance between the composite particles becomes high, as it becomes difficult for the thermally conductive or magnetic particles to come into contact with each other. Therefore, according to the second manufacturing process of the present disclosure, a urethane foam molded article can be produced that exhibits not only high thermal conductivity but also very good electrical insulating properties.

[0018] (10) In configuration (8) or (9), the amount of the surfactant mixed in during the composite particle manufacturing step can be 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the thermally conductive particle powder. According to the present configuration, it is preferred that both an improvement in the adhesion properties of the magnetic particles and a reduction in the influence of the foam urethane resin starting material on the foaming process are achieved. [Advantageous effects of the invention]

[0019] According to the urethane foam molded article of the present disclosure, high thermal conductivity can be achieved because the orientation of the composite particles is advantageous and a heat transfer path is formed by the interconnected composite particles. Furthermore, since the inuniformity in the configuration or size of the composite particles is low, the crosslinking and foaming reactions during foam molding can be easily controlled, and the moldability is excellent. Moreover, since the dispersibility of the composite particles is also advantageous, it is less likely that performance characteristics, such as heat dissipation properties, will vary with position. The method for producing a urethane foam molded article of the present disclosure is excellent with respect to the particle size of the composite particles.Furthermore, the urethane foam molded object of the present disclosure can be easily manufactured with high thermal conductivity according to the manufacturing process of the present disclosure, without affecting the foam molding. [Brief description of the drawings] Fig. Figure 1 shows particle size distributions of powders of composite particles A to C, which have been produced in examples. [Description of embodiments]

[0020] An embodiment of a urethane foam molded article of the present disclosure and a method for its manufacture are described below. The embodiment is not limited to the following shape and can be implemented in various modified or improved forms that can be carried out by a person skilled in the art. <urethanschaum-formgegenstand>

[0021] The urethane foam molded object of the present disclosure comprises a base material made of polyurethane foam and composite particles which are incorporated into and aligned within the base material. [Basic material]

[0022] The polyurethane foam of the base material is produced from a foam urethane resin starting material, such as a polyisocyanate component and a polyol component. The details are described in the process for producing a urethane foam molded article of the present disclosure, which is described below. The shape, size, and the like of the base material are not specifically limited and can be determined in a suitable manner depending on the applications. The composite particles incorporated into the base material must be oriented with a certain regularity. For example, the composite particles can be arranged linearly or in a curved shape between one end and the other end (which need not be an end part at 180° to one end) of the urethane foam molded article.Furthermore, the composite particles can be arranged radially from the center to the outer circumference. [Composite particles]

[0023] The composite particles consist of thermally conductive particles made of a non-magnetic material with a thermal conductivity of 200 W / m · K or higher, and magnetic particles attached to the surfaces of the thermally conductive particles with a binder.

[0024] The thermally conductive particles are made of a non-magnetic material. In this description, diamagnetic and paramagnetic materials, which differ from ferromagnetic and antiferromagnetic materials, are referred to as non-magnetic materials. The thermal conductivity of the thermally conductive particles is 200 W / m·K or higher. Examples of thermally conductive particles include graphite and expandable graphite. A single type of particle can be used as the thermally conductive particle, or two or more types of particles can be used together.

[0025] The shape of the heat-conducting particles is not specifically restricted, as long as the heat-conducting particles can form a composite with magnetic particles. For example, a variety of shapes can be used, such as a flake shape, a fiber shape, a column shape, a spherical shape, an elliptical shape, and an elongated shape (a shape in which a pair of facing hemispheres is coupled to a cylinder). In a case where the heat-conducting particles form a shape other than a sphere, the contact area between the composite particles becomes large. This makes it easier to ensure a heat transfer path and also increases the amount of heat that can be transferred. For example, graphite particles with a large aspect ratio are preferred because such composite particles can be produced at relatively low cost.

[0026] Examples of graphite include natural graphite, such as scale-like graphite, flaky graphite, and earthy graphite, as well as synthetic graphite and the like. Synthetic graphite is less likely to form a scale-like structure. Therefore, natural graphite is preferred because it exhibits a scale-like structure and a strong effect on improving thermal conductivity. Expandable graphite, which contains a substance that, when heated, generates a gas that penetrates between the scale-like graphite layers, can also be used as graphite. When the expandable graphite is heated, the space between the layers expands due to the generated gas, forming a layer that is stable against heat and chemicals. This stable layer acts as a heat insulator, hindering heat transfer and thus providing a flame-retardant effect.A preferred expandable graphite may be selected taking into account the expansion onset temperature, the expansion rate, or the like. For example, it is assumed that the expansion onset temperature of the expandable graphite is higher than the heat generation temperature during the molding of the urethane foam component. In particular, an expandable graphite with an expansion onset temperature of 150 °C or higher is preferred.

[0027] Normally, urethane foam molded parts exhibit a dripping effect that suppresses combustion by dripping sparks, even when exposed to a flame. However, if magnetic particles are added, there are concerns that the dripping effect could be impaired and the self-extinguishing properties of urethane foam molded parts could be deteriorated. Therefore, the composite particles in the urethane foam molded parts of the present disclosure are aligned. Consequently, it is likely that heat applied to the urethane foam molded parts will be transferred to the thermally conductive particles. Thus, in a case where the thermally conductive particles are made of expandable graphite, the expandable graphite rapidly reaches the temperature of onset of expansion. This allows the flame-retardant effect of the expandable graphite to be provided quickly.Therefore, the use of expandable graphite as the heat-conducting particles suppresses the deterioration of the self-extinguishing properties of the urethane foam molded item and allows the flame retardancy to be maintained.

[0028] The size of the thermally conductive particles can be determined taking into account dispersibility, the size of the base material, or similar factors. To increase the thermal conductivity of the urethane foam molded part, the average particle diameter of the thermally conductive particles is preferably 200 µm or more. Conversely, when considering the dispersibility of the composite particles, the average particle diameter is preferably 2000 µm or less. Unless otherwise specified, the average particle diameter used in this description is the median diameter (D50) obtained from the volume-based particle size distribution measured by laser diffraction and scattering. For commercially available products, catalog values ​​may be used.

[0029] The magnetic particles are attached to the surfaces of the heat-conducting particles using a binder and play a role in aligning these particles. The magnetic particles must have excellent magnetization properties and are made of iron and stainless steel. These materials are easy to manufacture as fine particles and exhibit high saturation magnetization. Iron, in particular, is relatively inexpensive to produce, thus reducing manufacturing costs and making it preferable for mass production.

[0030] The magnetic particles can be attached directly to the surfaces of the thermally conductive particles or indirectly via other particles, such as insulating inorganic particles, as described below. Furthermore, the magnetic particles can be attached to only a portion of the surfaces of the thermally conductive particles or can be applied in such a way that they coat all surfaces. The size of the magnetic particles can be suitably determined by considering the size of the thermally conductive particles, the orientation of the composite particles, the thermal conductivity between the composite particles, or similar factors. For example, the diameter of the magnetic particles is preferably 1 / 10 or less than the diameter of the thermally conductive particles.As the size of the magnetic particles decreases, their saturation magnetization tends to deteriorate. Therefore, the average diameter of the magnetic particles must be set to 100 nm or more to align the composite particles with a smaller quantity of magnetic particles. The average particle diameter is more preferably 1 µm or more, and furthermore 5 µm or more.

[0031] The shape of the magnetic particles is not specifically restricted. For example, if the magnetic particles are flat, the distance between adjacent thermally conductive particles is short compared to a spherical shape. Therefore, the thermal conductivity between adjacent particles improves. As a result, the thermal conductivity of the urethane foam molded object is improved. Furthermore, if the magnetic particles are flat, they and the thermally conductive particles come into surface contact. That is, the contact area between the two particles becomes large. Therefore, the bonding force between the magnetic and thermally conductive particles is strengthened. Consequently, it is less likely that the magnetic particles will detach.Additionally, the thermal conductivity between the magnetic particles and the heat-conducting particles is also improved. For these reasons, flake-shaped particles are preferably used as the magnetic particles.

[0032] In a case where a highly electrically conductive material is used for the thermally conductive particles or the magnetic particles, an electrical conduction path is formed in the base material due to the composite particles being aligned in a state where they are interconnected. Therefore, for applying the urethane foam molded article of the present disclosure to elements requiring electrical insulating properties, such as heat dissipation elements in electronic devices, it is preferred to impart electrical insulating properties to the urethane foam molded article. For example, it is preferred to form the composite particles by attaching insulating inorganic particles to the surfaces of the thermally conductive particles in addition to the magnetic particles.In such a case, it is less likely that the thermally conductive or magnetic particles (electrically conductive particles) between adjacent composite particles will come into contact with each other, even if the composite particles are aligned. Therefore, the electrical resistance between the composite particles becomes high. Furthermore, the insulating inorganic particles bring the composite particles into contact with each other, which can interrupt electrical conduction between them.

[0033] The insulating inorganic particles must be particles of an inorganic material with insulating properties. In particular, particles of an inorganic material with a relatively high thermal conductivity are preferred, so that the thermal conductivity between the composite particles is not impaired. For example, the thermal conductivity of the insulating inorganic particles is preferably 5 W / m·K or higher. Examples of insulating inorganic materials with a thermal conductivity of 5 W / m·K or higher include aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium oxide, talc, calcium carbonate, clay, mica, silicon dioxide, and the like.

[0034] The insulating inorganic particles can be applied directly to the surfaces of the thermally conductive particles or indirectly via the magnetic particles. Furthermore, the insulating inorganic particles can be applied only to a portion of the surfaces of the thermally conductive particles or can be applied in such a way that all surfaces are coated. To increase the electrical resistance between the composite particles and thus improve the electrical insulating properties of the urethane foam molded part, the insulating inorganic particles are preferably arranged in the outermost layers of the composite particles.

[0035] The size of the insulating inorganic particles can be suitably determined by considering their adhesion properties to the thermally conductive and magnetic particles, their electrical insulating properties, and the thermal conductivity between the composite particles. If the insulating inorganic particles are too large, the adhesion properties or the thermal conductivity between the composite particles will deteriorate. For example, the particle diameter of the insulating inorganic particles is preferably 1 / 100 or more and 1 / 10 or less than the particle diameter of the thermally conductive particles. The shape of the insulating inorganic particles is not specifically restricted.For example, if the insulating inorganic particles are flat, the distance between adjacent thermally conductive particles can be reduced compared to a spherical shape. Therefore, the thermal conductivity between adjacent composite particles is less likely to be affected. Furthermore, the contact area becomes larger, making it less likely that the insulating inorganic particles will detach.

[0036] The binder used to attach the thermally conductive particles and magnetic particles, or the like, can be selected appropriately, taking into account the type of particles, their influence on foaming, and other factors. A water-soluble binder is preferred because it has a low impact on foaming and is environmentally friendly. Examples include methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, polyvinyl alcohol, starch, and the like. The binder used to attach the magnetic particles and the binder used to attach the insulating inorganic particles can be the same or different.

[0037] The composite particles are surface-treated with one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant (hereinafter conveniently referred to as "carboxylic acid-type / succinic acid-type surfactant"). The surface treatment can be carried out on only a portion of the composite particles (for example, only the surfaces of the magnetic particles or the like) or on all composite particles.

[0038] The carboxylic acid / succinic acid-type surfactant features a carboxyl group (-COOH) as a polar group. This polar group reacts with a hydroxyl group (-OH) or similar compound present on the surface of the thermally conductive or magnetic particles, thereby accelerating adhesion between the two. Furthermore, the surfactant is adsorbed onto the surface of the thermally conductive or magnetic particles by the polar group, while water or oxygen is blocked by a hydrophobic group on the opposite side, thus imparting anti-corrosion properties. Therefore, the materials forming the composite particles are less likely to rust, even when water is used during granulation.As described above, the use of a carboxylic acid / succinic acid-type surfactant not only improves the adhesion between the particles but is also effective in protecting the composite particles from corrosion. Therefore, manufacturing costs can be reduced by using relatively inexpensive materials, such as iron, for the magnetic particles.

[0039] Examples of carboxylic acid-type surfactants include alkyl ether carboxylates and the like. Examples of succinic acid-type surfactants include metal salts of alkenyl succinate and the like. Of these, the succinic acid-type surfactant not only has a low impact on foaming but also exhibits excellent corrosion protection properties and is therefore preferred. Furthermore, the carboxylic acid / succinic acid-type surfactant is water-soluble and can be dissolved in water and added during the granulation of the composite particles, thus simplifying the surface treatment.

[0040] The content of the composite particles in the urethane foam molded article of the present disclosure can be determined taking into account a thermal conductivity improvement effect, the influence on a foaming reaction, formability, or the like. For example, the content of the composite particles is preferably set to 20 vol% or less in a case where the volume of the urethane foam molded article is set to 100 vol%, in order to obtain a urethane foam molded article with desired physical properties without impairing a foaming reaction. The content is more preferably set to 15 vol% or less. On the other hand, the content of the composite particles is preferably set to 3 vol% or more to increase the thermal conductivity. The content is more preferably set to 10 vol% or more.

[0041] Furthermore, with a view to improving the granulation properties and reducing the number of magnetic particles that do not constitute the composite particles, the proportion of small particles with a particle diameter of 100 µm or less in the particle size distribution of the composite particles is preferably 10 wt% or less when the total mass of the composite particles is set to 100 wt%. In this description, a mass-based frequency distribution obtained by a sieving process is used as the particle size distribution of the composite particles, and the proportion of small particles is calculated based on this frequency distribution.

[0042] The urethane foam molded article of the present disclosure may further comprise insulating inorganic particles dispersed in the base material. That is, insulating inorganic particles may be dispersed in the base material in addition to the aligned composite particles. The insulating inorganic particles dispersed in the base material may be identical to or different from the insulating inorganic particles added as constituent particles of the composite to impart electrical insulating properties. Furthermore, the number of types of insulating inorganic particles dispersed in the base material may be one or more.The insulating inorganic particles dispersed in the base material preferably have a relatively high thermal conductivity, and aluminum hydroxide, aluminum oxide, magnesium hydroxide, magnesium oxide, talc, calcium carbonate, clay, mica, silicon dioxide, and the like are preferred. When the insulating inorganic particles are dispersed in the base material, they penetrate between the composite particles, and it is less likely that the composite particles will be electrically conductive to each other. Therefore, the electrical insulating properties of the urethane foam molded part are improved. Furthermore, in cases where the thermal conductivity of the insulating inorganic particles is relatively high, an additional heat transfer path is formed through the insulating inorganic particles, besides the heat transfer path through the composite particles.Therefore, the thermal conductivity of the urethane foam molded part is further improved. Furthermore, the flame retardancy of the urethane foam molded part is improved in cases where the insulating inorganic particles are flame retardant. <Verfahren zur Herstellung eines Urethanschaum-Formgegenstands>

[0043] The process for manufacturing a urethane foam molded article of the present disclosure is not specifically limited. As a preferred manufacturing process, the process for manufacturing a urethane foam molded article of the present disclosure comprises a composite particle manufacturing step, a mixed starting material manufacturing step, and a foam forming step. Each step is described below. [Composite particle manufacturing step]

[0044] The present step is a step of producing composite particles by stirring a granulation starting material comprising a powder of thermally conductive particles made from a non-magnetic material and having a thermal conductivity of 200 W / m·K or higher, a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water.

[0045] The thermally conductive particles, the magnetic particles, the binder, and the surfactants are as described above. Therefore, their description is omitted. Furthermore, the quantities of the powdered thermally conductive particles, the powdered magnetic particles, and the binder that are mixed can be adjusted appropriately, taking into account the magnetic field orientation of the composite particles to be produced, and the thermal conductivity in cases where the composite particles are mixed with a urethane foam molded part or the like.

[0046] For example, in a case where graphite is used as the thermally conductive particles, the amount of thermally conductive particle powder added is preferably set to 100 parts by mass or more, and 200 parts by mass or less, based on 100 parts by mass of graphite powder. In a case where the amount of added magnetic powder is less than 100 parts by mass, there is concern that the magnetic properties required for the alignment of the composite particles may be lacking, as the amount of magnetic particles is small. On the other hand, if the amount added exceeds 200 parts by mass, the amount of magnetic particles becomes excessive. Therefore, the mass of the urethane foam molded part increases, or the cost increases with the excessive amount.

[0047] The amount of binder added is preferably 2% by mass or more, and 4% by mass or less than a sufficient amount to ensure particle adhesion when the total mass of the powders being attached is fixed at 100% by mass. If the amount of binder added is less than 2% by mass, it will not spread across the particle surfaces, and the adhesion properties will deteriorate. Conversely, if the amount added exceeds 4% by mass, there is a risk of agglomeration of the composite particles due to the excess binder. The binder may be a solid or a liquid. If a water-soluble powder is used as the binder, water may be added after the binder and the powders have been pre-mixed with other starting materials.In such a case, the agglomeration of the particles can be prevented.

[0048] The amount of the carboxylic acid / succinic acid-type surfactant added can be suitably determined depending on the amount of thermally conductive particles, magnetic particles, or the like added. To improve the adhesion properties of the magnetic particles, the amount of the carboxylic acid / succinic acid-type surfactant added is preferably 0.1 parts by mass or more per 100 parts by mass of the thermally conductive particle powder. More preferably, the amount added is 0.3 parts by mass or more. On the other hand, if the influence of a foam urethane resin starting material on foam formation is taken into account, the amount added is preferably 30 parts by mass or less. More preferably, the amount added is 20 parts by mass or less.

[0049] The present step can be designed to include a preliminary stirring step of a starting material containing water, powdered thermally conductive particles, powdered magnetic particles, and a binder, and a main stirring step of adding a surface treatment agent, obtained by dissolving a carboxylic acid / succinic acid-type surfactant in water, to a stirred product of the starting material, followed by further stirring of the mixture. In the preliminary stirring step, the powdered starting materials and the binder are first stirred after the addition of water, which prevents agglomeration of the powdered starting material particles.Next, in the main stirring step, adding the surfactant, which was obtained beforehand by dissolving it in water, makes it easier for the surfactant to spread across and react with all magnetic particles, compared to adding the surfactant directly. Furthermore, this configuration can be easily applied even when using a surfactant with poor water solubility.

[0050] Furthermore, in a case where insulating inorganic particles are added as building blocks of the composite particles, the powder of the insulating inorganic particles can be included in the granulation starting material.In a case where the insulating inorganic particles are arranged in the outermost layers of the composite particles, the present step may be designed to include a first stirring step of stirring a first starting material comprising a powder of thermally conductive particles made from a non-magnetic material having a thermal conductivity of 200 W / m·K or higher, a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water, and a second stirring step of adding and further stirring a powder of the insulating inorganic particles to and into a stirred product of the first starting material (second manufacturing process).Furthermore, in a case where the present step consists of the preliminary stirring step and the main stirring step as described above, the insulating inorganic particles can be added and stirred after the main stirring step.

[0051] For example, in a case where graphite is used as the thermally conductive particles, the amount of added insulating inorganic powder is preferably set to 30 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the graphite powder. In a case where the added amount is less than 30 parts by mass, the effect of imparting electrical insulating properties is minimal, since the amount of insulating inorganic particles is small. On the other hand, if the added amount exceeds 100 parts by mass, the amount of insulating inorganic particles becomes large, and the thermal conductivity between the composite particles decreases. Therefore, the thermal conductivity of the urethane foam molded part decreases.

[0052] The composite particles can be obtained by suitable drying of the stirred granulation feedstock (the stirred product obtained in the second stirring step of the second manufacturing process described above). In the resulting composite particles, the proportion of small particles with a particle diameter of 100 µm or less is preferably 10 wt% or less, in a case where the total mass of the composite particles is set at 100 wt%. If the proportion of small particles is low, it can be assumed that the desired composite particles have been produced with a relatively large quantity of the attached magnetic particles or the like, and the alignment of the composite particles in the subsequent foaming step can be achieved even with a relatively weak magnetic field.Furthermore, a step involving the removal of small particles, taking into account malleability, is not necessary. [Mixed starting material manufacturing step]

[0053] The present step is a step of producing a mixed starting material by mixing a powder of the composite particles, which was produced in the previous step, and a foamed urethane resin starting material. The composite particles can be used as produced in the resulting powder, or they can be used after any large particles have been removed in a suitable manner, or the like.

[0054] The foam urethane resin starting material can be produced from known starting materials, such as a polyol or a polyisocyanate. The polyol can be selected appropriately from polyhydric hydroxy compounds, polyether polyols, polyester polyols, polymer polyols, polyether polyamines, polyester polyamines, alkylene polyols, urea-dispersed polyols, melamine-modified polyols, polycarbonate polyols, acrylic polyols, polybutadiene polyols, phenol-modified polyols, and the like. Furthermore, the polyisocyanate can be selected appropriately from, for example, toluene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl diisocyanate, naphthalene diisocyanate, derivatives thereof (e.g., prepolymers obtained by reaction with polyols and modified polyisocyanates), and the like.

[0055] The foam urethane resin starting material can optionally be mixed with a catalyst, blowing agent, foam stabilizer, plasticizer, crosslinking agent, chain extender, flame retardant, antistatic agent, thinner, stabilizer, filler, colorant, or the like. Examples of catalysts include amine-based catalysts such as tetraethylenediamine, triethylenediamine, and dimethylethanolamine, and organometallic catalysts such as tin laurate and tin octoate. Water is a preferred blowing agent. Examples of suitable blowing agents include methylene chloride, fluorocarbons, CO2 gas, and the like. A silicone-based foam stabilizer is also preferred, and triethanolamine, diethanolamine, and the like are preferred crosslinking agents.In the urethane foam molded article of the present disclosure, the insulating inorganic particles can be dispersed separately from the composite particles in the base material, as described above. When producing this type of urethane foam molded article, the powder of the composite particles and the powder of the insulating inorganic particles can be mixed with the foam urethane resin starting material.

[0056] The mixed starting material can be produced, for example, by mechanically stirring the powder of the composite particles and the foamed urethane resin starting material using a stirring paddle or the like. Alternatively, the mixed starting material can also be produced by preparing two types of starting materials by adding the powder of the composite particles to at least one of the two components (a polyol starting material and a polyisocyanate starting material) of the foamed urethane resin starting material and then mixing the two starting materials. As described above, to obtain a urethane foam molded part with desired physical properties without impairing a foaming reaction, the amount of powder of the added composite particles is preferably adjusted to 20 vol.% or less in a case where the volume of the urethane foam molded part is set to 100 vol.%.The amount added is preferably adjusted to 15% by volume or less. On the other hand, the amount of powder containing the added composite particles is preferably adjusted to 3% by volume or more to achieve the thermal conductivity improvement effect. The amount added is more preferably adjusted to 10% by volume or more. [Foam forming step]

[0057] The present step is a step of pouring the mixed starting material, which was produced in the previous step, into the cavity of a foam molding tool and carrying out foam molding while a magnetic field is applied such that the magnetic flux density in the cavity becomes substantially uniform.

[0058] The magnetic field must be generated in a direction corresponding to the orientation of the composite particles. For example, in a case where the composite particles are linearly oriented, the magnetic field is preferably generated such that the magnetic field lines within the cavity of the foam mold are substantially parallel from one end to the other. To generate such a magnetic field, magnets must be positioned near both surfaces of the foam mold, surrounding it. Permanent magnets or electromagnets can be used. If electromagnets are used, they can be instantly switched on and off to generate the magnetic field, and the intensity of the magnetic field can be easily adjusted and controlled. Therefore, the foam molding process can be easily set and controlled.Furthermore, the magnetic field lines that form the magnetic field preferably form a closed loop. In such a case, the escape of the magnetic field lines is prevented and a stable magnetic field can be formed in the cavity.

[0059] In the present step, the magnetic field is configured such that the magnetic flux density in the cavity becomes essentially uniform. For example, the difference in magnetic flux density in the cavity is preferably within ±10%. More preferably, the difference is within ±5%, and furthermore, within ±3%. The uniform magnetic field generated in the cavity of the foam mold prevents uneven distribution of the composite particles and ensures a desired alignment. Furthermore, foam molding is preferably carried out at a magnetic flux density of 150 mT or higher and 350 mT or lower. In such cases, the composite particles in the mixed starting material can be reliably aligned.

[0060] It is preferable to apply the magnetic field while the viscosity of the foamed urethane resin starting material is relatively low. If the magnetic field is applied after the viscosity of the foamed urethane resin starting material has increased and the foaming process is largely complete, it is difficult to align the composite particles, and consequently, it is difficult to achieve the desired thermal conductivity. There is no need to apply the magnetic field for the entire duration of the foaming process.

[0061] After the foam molding process is completed in the present step, the molding tool is released and the urethane foam molded object of the present disclosure is obtained. Depending on how the foam molding is to be carried out, a skin layer is formed at least at one end and at the other end of the urethane foam molded object. The skin layer can be removed depending on the application (it is understood that the skin layer may not need to be removed if necessary). Examples

[0062] Next, the present revelation will be described in more detail using examples. <Herstellung von Verbundteilchen>

[0063] First, three types of composite particles A to C were produced in the manner described below. [Composite particle A]

[0064] A granulation starting material comprising a powder of thermally conductive particles, a powder of magnetic particles, a binder, a succinic acid-type surfactant, a powder of insulating inorganic particles, and water was stirred to produce composite particles A (composite particle production step). First, powders of two types of thermally conductive particles, powders of two types of magnetic particles, and a binder were placed in the container of a high-speed stirred mixing granulator and mixed by a paddle stirrer. Water was then added to the mixture, and the components were mixed for one minute. Next, a surfactant obtained by dissolving a succinic acid-type surfactant in water was added to the mixture while stirring for approximately 1.5 minutes.A powder of insulating inorganic particles was then introduced into the mixture, and the components were mixed for four minutes. The stirring speed was set to 400 rpm. The resulting powder was dried and considered to be the powder of compound particles A. The details of the materials used are described below, and their quantities are shown in Table 1 (this also applies to the following compound particles B and C). (a) Heat-conducting particles Expandable graphite powder-1: “SYZR502FP”, manufactured by Shijiazhuang-Aidite Trading Co., Ltd., particle diameter: 300 to 500 µm, thermal conductivity: 200 W / m · K. Expandable graphite powder-2: “AED-03”, manufactured by Fujikokuen Co., Ltd., particle size (sieve mesh size) of 3 mm: 80%, thermal conductivity: 200 W / m · K. (b) Magnetic particles Stainless steel powder: “AKT”, manufactured by Mitsubishi Steel Mfg. Co., Ltd., average particle diameter: 11.5 µm. Iron powder: “SDP-4”, manufactured by Dowa Electronics Materials Co., Ltd., average particle diameter: 45 µm. (c) Insulating inorganic particles Talc powder: “MICR ACE (registered trademark) K-1”, manufactured by Nippon Talc Co., Ltd., average particle diameter: 8 µm. (d) Binders Strength: “INSTANT TENDER-JEL C”, manufactured by Nihon Cornstarch Corporation. (e) Surfactant of the succinic acid type Anionic surfactant of the succinic acid type: “SANHIBITOR (registered trademark) OMA-10”, manufactured by Sanyo Chemical Industries, Ltd. [Table 1] Granulation starting material Composite particles A Composite particles B Composite particlesC Heat-conducting particles[g] Expandable graphite powder-1 500 500 500 Expandable Graphite Powder-2 500 500 500 Magnetic particles [g] Powder made of stainless steel 500 500 500 iron powder 800 800 800 Insulating inorganic particles [g] talc powder 400 400 400 Binder [g] Strength 72 72 72 Surface-active agent [g] Succinic acid type 7 - - Amine-based - 7 - Water [g] 294 294 294 [Composite particle B]

[0065] Compound particles B were produced using the same process as the process for producing compound particles A, except that the succinic acid-type surfactant was changed to a non-ionic amine-based surfactant (“SANHIBITOR No. 50”, manufactured by Sanyo Chemical Industries, Ltd.). [Composite particle C]

[0066] Composite particles C were produced using the same procedure as for composite particles A, except that the surfactant was omitted. Specifically, powders of two types of thermally conductive particles, powders of two types of magnetic particles, and a binder were mixed. Water was then added to the mixture, and the components were mixed for one minute. A powder of insulating inorganic particles was then introduced, and the components were mixed for four minutes. Finally, the resulting powder was dried and considered to be composite particle C. [Particle size distribution]

[0067] The powders of composite particles A to C were sieved to measure the particle size distributions. Sieving was carried out using metal sieves with mesh sizes of 45 µm, 100 µm, 300 µm, 500 µm, 710 µm, 1000 µm, 2000 µm, and 3350 µm. Fig. Figure 1 shows the particle size distribution of the powder for each type of compound particle. As shown in the Fig. As shown in Figure 1, it was confirmed that, compared to the particle size distribution of the powder of composite particles C granulated without the use of the surfactant, the proportions of small particles with a diameter of 100 µm or less were low in the particle size distributions of the powders of composite particles A and B granulated using the surfactant. In Table 2, shown below, cases where the proportion of small particles with a diameter of 100 µm or less was 10 wt% or less of all composite particles are indicated by the symbol O, and a case where the proportion exceeded 10 wt% is indicated by the symbol Δ. [Rust protection properties]

[0068] The powders of composite particles A to C were visually inspected, and the presence or absence of rust was confirmed. As a result, the formation of rust in composite particles A and B, which were granulated using the surfactant, was not confirmed; however, the formation of rust in composite particles C, which were granulated without the use of the surfactant, was confirmed, as shown in Table 2 below. <Herstellung eines Urethanschaum-Formgegenstands> [Sample 1]

[0069] A urethane foam molded part was manufactured using the generated composite particles A. First, 100 parts by mass of a polyether polyol (“S-0248”, manufactured by Covestro AG), 2 parts by mass of diethylene glycol (manufactured by Mitsubishi Chemical Corporation) as a chain extender, 2 parts by mass of water as a blowing agent, 1.5 parts by mass of a tetraethylenediamine-based catalyst (“KAOLIZER (registered trademark) No. 31”, manufactured by Kao Corporation), and 0.5 parts by mass of a silicone-based foam stabilizer (“SZ-1333”, manufactured by DuPont Toray Specialty Materials Kabushiki Kaisha) were mixed to produce a polyol starting material. Additionally, a diphenylmethane diisocyanate (MDI)-modified product was prepared as a polyisocyanate starting material.The MDI-modified product was prepared by mixing a polyether polyol (the same as above) and 4,4'-diphenylmethane diisocyanate (“MILLIONATE MT”, manufactured by Tosoh Corporation) to achieve an isocyanate (NCO) content of 70 wt% and inducing a reaction at 100 °C for 180 minutes under a nitrogen stream. Next, 129.7 wt parts of the compound particles A were added to and mixed with 100 wt parts of the polyol starting material, producing a polyol premix. Subsequently, 100.6 g of the polyol premix and 13.7 g of the polyisocyanate starting material were mixed together and considered the mixed starting material (mixed starting material preparation step).

[0070] The mixed starting material was then poured into an aluminum foam mold (the cavity was a cuboid with a length of 130 mm, a width of 130 mm, and a thickness of 20 mm), and the mold was closed or sealed. The mold was then placed in a magnetic induction foam molding device, and the foam molding process was carried out. A uniform magnetic field with magnetic field lines running essentially parallel from top to bottom was generated within the mold cavity. The magnetic flux density in the cavity was 200 mT, and the variation in magnetic flux density within the cavity was within ±3%. The foam molding process was carried out with the magnetic field applied for the first two minutes and then without the magnetic field for approximately five minutes (foam molding step).After the foam molding process was complete, the mold was released, and a urethane foam molded item was obtained. The obtained urethane foam molded item is referred to as the urethane foam molded item of Sample 1. The content of the composite particles A in the urethane foam molded item of Sample 1 was 4 vol% when the volume of the urethane foam molded item was set to 100 vol%, and 42 wt% when the mass of the urethane foam molded item was set to 100 wt%. The urethane foam molded item of Sample 1 is incorporated into the concept of the urethane foam molded item of the present disclosure. [Sample 2]

[0071] A urethane foam molded object of sample 2 was produced using the same process as the process for producing sample 1, except that the composite particles A were changed to composite particles B. [Sample 3]

[0072] A urethane foam molded object of sample 3 was produced using the same process as the process for producing sample 1, except that the composite particles A were changed to composite particles C. <Bewertung von Urethanschaum-Formgegenständen>

[0073] The formability and thermal conductivity of the three produced samples were evaluated. Regarding formability, the Asker C hardness of each sample was measured using an "ASKER Durometer Type C" manufactured by Kobunshi Keiki Co., Ltd. and evaluated based on the Asker C hardness values ​​of sample 3 with the composite particles C granulated without the use of the surfactant. That is, if the Asker C hardness value was within ±5% of that of sample 3, it was assessed that there was no effect on foaming (indicated by the symbol O in Table 2 below); otherwise, it was assessed that there was an effect on foaming (indicated by the symbol × in the same table). Regarding thermal conductivity, the thermal conductivity of each sample was determined using "HC-110" manufactured by EKO Instruments Co., Ltd.The thermal conductivity was measured according to the heat flow measurement method of JIS A 1412-2: 1999 and evaluated based on the thermal conductivity values ​​of Sample 3, which contains the composite particles C. That is, if the thermal conductivity value was equal to or greater than that of Sample 3, the thermal conductivity was rated as advantageous (indicated by the symbol O in Table 2 below), and if the value was less, the thermal conductivity was rated as detrimental (indicated by the symbol × in the same table). Table 2 shows the evaluation results for formability and thermal conductivity. [Table 2] Sample 1 Sample 2 Sample 3 Composite particles A B C Surface-active agent Succinic acid type Amine-based None Particle size distribution ◯ ◯ Δ Presence or absence of rust Missing Missing Is available Urethane foam molded object Malleability (influence on foam forming) ◯ × - thermal conductivity ◯ × -

[0074] As shown in Table 2, in the urethane foam molded item of sample 1 with composite particles A, which were surface-treated with the succinic acid-type surfactant, the thermal conductivity did not decrease and no effects on the foaming process were observed; however, in the urethane foam molded item of sample 2 with composite particles B, which were surface-treated with the amino-based surfactant, the thermal conductivity and hardness decreased and an effect on the foaming process was confirmed. [Commercial Applicability]

[0075] The urethane foam molded article of the present disclosure can be used in a wide range of fields, such as motor vehicles, electronic devices, and buildings. For example, the urethane foam molded article is preferred as a soundproofing material in machines, engines, EGR valves, and the like, which are arranged in motor vehicle engine compartments; as a soundproofing material for an engine used in office automation (OA) equipment or household appliances; or as a soundproofing material used in electronic devices, such as a personal computer.

Claims

[1] Urethane foam molded object comprising: a base material made from polyurethane foam; and Composite particles that are incorporated into and aligned within the base material, wherein the composite particles comprise thermally conductive particles formed from a non-magnetic material and having a thermal conductivity of 200 W / m · K or higher, and magnetic particles attached to surfaces of the thermally conductive particles with a binder and surface-treated with one or more surfactant(s) selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, wherein the heat-conducting particles comprise at least one of graphite particles and expandable graphite particles, and wherein the magnetic particles include at least one iron particle and one stainless steel particle. [2] Urethane foam molded article according to claim 1, wherein the surfactant of the succinic acid type is included as the surfactant. [3] Urethane foam molded article according to claim 1 or 2, wherein the surfactant is water-soluble. [4] Urethane foam molded article according to one of claims 1 to 3, wherein in a particle size distribution of the composite particles a content of small particles with a particle diameter of 100 µm or less is 10 mass-% or less in a case where the total mass of the composite particles is set to 100 mass-%. [5] Urethane foam molded article according to any one of claims 1 to 4, wherein an average particle diameter of the heat-conducting particles is 200 µm or more and 2000 µm or less. [6] Urethane foam molded article according to any one of claims 1 to 5, wherein the magnetic particles comprise iron particles. [7] Urethane foam molded article according to any one of claims 1 to 6, wherein the composite particles comprise insulating inorganic particles which are attached to the surfaces of the heat-conducting particles with a binder. [8] Urethane foam molded article according to claim 1, wherein an average particle diameter of the heat-conducting particles is 200 µm or more and 2000 µm or less, the magnetic particles contain iron particles, The composite particles contain insulating inorganic particles that are attached to the surfaces of the heat-conducting particles with a binder. in a particle size distribution of the composite particles, a content of small particles with a particle diameter of 100 µm or less is 10 mass-% or less in a case where the total mass of the composite particles is fixed at 100 mass-%, and The surfactant is a succinic acid-type surfactant and is water-soluble. [9] Method for producing the urethane foam molded article according to claim 1, wherein the method comprises: a composite particle manufacturing step of producing composite particles by stirring a granulation starting material comprising a powder of thermally conductive particles made from a non-magnetic material having a thermal conductivity of 200 W / m · K or higher, a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water, wherein the thermally conductive particles comprise at least one of graphite particles and expandable graphite particles, and wherein the magnetic particles comprise at least one of iron particles and stainless steel particles; a mixed starting material manufacturing step of producing a mixed starting material by mixing a powder of the composite particles and a foam urethane resin starting material; and a foam forming step of pouring the mixed starting material into a cavity of a foam forming tool and performing foam forming while a magnetic field is applied such that a magnetic flux density in the cavity becomes essentially uniform. [10] Method for producing the urethane foam molded article according to claim 7, wherein the method comprises: a composite particle manufacturing step of the manufacturing of composite particles; a mixed starting material manufacturing step of producing a mixed starting material by mixing a powder of the composite particles and a foam urethane resin starting material; and a foam forming step of pouring the mixed starting material into a cavity of a foam forming tool and performing foam forming while a magnetic field is applied such that a magnetic flux density in the cavity becomes essentially uniform, where the composite particle manufacturing step a first stirring step of stirring a first starting material comprising a powder of thermally conductive particles made from a non-magnetic material having a thermal conductivity of 200 W / m·K or higher, a powder of magnetic particles, a binder, one or more surfactants selected from a carboxylic acid-type surfactant and a succinic acid-type surfactant, and water, wherein the thermally conductive particles comprise at least one of graphite particles and expandable graphite particles, and wherein the magnetic particles comprise at least one of iron particles and stainless steel particles, and a second stirring step of adding and further stirring a powder of insulating inorganic particles to a stirred product of the first starting material. [11] Method according to claim 9 or 10, wherein the amount of the surfactant mixed in during the composite particle manufacturing step is 0.1 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the powder of the thermally conductive particles.

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