JP2010069742A - Urethane foam molded product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a urethane foam molded product having high heat transfer properties without inhibiting sound absorbing characteristics, and to provide a method for manufacturing the same. <P>SOLUTION: This urethane foam molded product comprises a substrate made of a polyurethane foam and a magnetic filler compounded in the substrate and aligned in conjunction with each other, where the filler is made from an iron alloy of iron and a metal with a thermal conductivity of 150 W/(m×K) or more; and the relationship between the iron content x (wt.%) in the iron alloy and the filler volume y (mm<SP>3</SP>) falls within the area surrounded by point A (10, 0.25), point B (10, 0.01), point C (65, 0.0007), point D (90, 0.0007) and point E (90, 0.25) in Fig.1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a urethane foam molded article used as, for example, a sound absorbing material or a vibration absorbing material, and a method for producing the same.

  Urethane foam moldings are used in various fields such as automobiles as sound absorbing materials, vibration absorbing materials and the like. The urethane foam molding has a low thermal conductivity because it has a large number of cells (bubbles) inside. For this reason, when it arrange | positions around an engine, a motor, etc. with a heat_generation | fever, heat | fever accumulate | stores and there exists a possibility of producing a malfunction. In order to solve such a problem, an attempt has been made to improve the heat dissipation of the urethane foam molded article.

For example, a soundproof tire disclosed in Patent Document 1 includes a sound absorbing material in which a heat conductive material such as alumina powder is blended with polyurethane foam. Patent Document 2 discloses a sound absorbing material made of polyurethane foam having oriented magnetic particles.
JP-A-2005-104314 JP 2007-230544 A Japanese Patent Publication No. 3-64583

  As in the sound absorbing material disclosed in Patent Document 1, when a heat conductive material is blended with a base material made of polyurethane foam, a heat transfer path is formed by contact between the heat conductive materials. For this reason, the heat dissipation of the sound absorbing material is improved. However, in order to improve heat dissipation, a large amount of heat conducting material is required. When the blending amount of the heat conducting material is increased, the foam molding may be affected and the sound absorption characteristics may be deteriorated. In this regard, according to the sound absorbing material disclosed in Patent Document 2, the magnetic particles in the polyurethane foam are connected in a chain and oriented. Therefore, heat dissipation can be improved with a relatively small amount of magnetic particles.

  As described in Patent Document 2, the magnetic particles are oriented along the lines of magnetic force during foam molding in a magnetic field. In order to obtain a desired orientation state, stainless steel having excellent magnetization characteristics is used for the magnetic particles. However, the thermal conductivity of stainless steel is low. Therefore, even if the stainless steel particles are oriented, it is difficult to improve the heat dissipation to a satisfactory level.

  This invention is made | formed in view of such a situation, and makes it a subject to provide a urethane foam molded object with high heat transfer, and its manufacturing method, without inhibiting a sound absorption characteristic.

  In order to solve the above-mentioned problems, the present inventor has repeatedly studied magnetic fillers oriented in polyurethane foam. For example, Patent Document 3 discloses a copper-iron alloy made of nonmagnetic copper and ferromagnetic iron. The thermal conductivity of copper is 398 W / (m · K). On the other hand, the conductivity of iron is 84 W / (m · K). Thus, the thermal conductivity of copper is greater than the thermal conductivity of iron. Therefore, it was expected that a magnetic filler made of a copper-iron alloy having a large copper content would be effective in improving heat transfer if it was oriented in polyurethane foam. However, if the copper content is high, the iron content is reduced accordingly. That is, when the copper content is increased, the magnetization characteristics of the copper-iron alloy are degraded. For this reason, there has been a problem that the desired orientation state of the magnetic filler cannot be obtained when foam molding is performed in a magnetic field simply by increasing the copper content.

  In general, the force that a magnetic field exerts on a magnetic filler is determined by the product of the magnetic moment of the magnetic filler and the magnetic field gradient. The magnetic moment is the product of the magnetization and volume of the magnetic filler. Here, the magnetization varies depending on the composition of the magnetic filler and the strength of the applied magnetic field. Therefore, the magnetic moment changes depending on the composition and volume (size) of the magnetic filler if the strength of the applied magnetic field, that is, the magnetic flux density is constant. That is, when the magnetic flux density is constant, the force exerted on the magnetic filler varies depending on the composition and volume of the magnetic filler. For this reason, even if the magnetic filler has a composition with low magnetization characteristics (not easily oriented), a desired orientation state can be obtained by optimizing its volume.

The urethane foam molded article of the present invention made based on such knowledge has a base material made of polyurethane foam, and a magnetic filler blended in the base material and oriented in an interconnected manner, The magnetic filler is made of an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more. The iron content x (wt%) in the iron alloy and the volume y ( mm ³ ), point A (10, 0.25), point B (10, 0.01), point C (65, 0.0007), point D (90, 0.0007) in FIG. , The region is surrounded by a point E (90, 0.25) (corresponding to claim 1).

  That is, the urethane foam molded article of the present invention has a magnetic filler whose composition and volume are optimized in order to achieve both high thermal conductivity and magnetization characteristics. The magnetic filler is made of an iron alloy containing a metal having a thermal conductivity of 150 W / (m · K) or more. Therefore, the thermal conductivity of the magnetic filler is high. By orienting such a magnetic filler, the heat transferability of the urethane foam molded article can be improved. Moreover, compared with the case where the magnetic filler made from stainless steel with low heat conductivity is used, heat transfer property can be improved with a smaller compounding amount.

  For example, copper can be used as the metal having a thermal conductivity of 150 W / (m · K) or more. In this case, even if the copper content is as high as 90% by weight (point A in FIG. 1, the iron content is 10% by weight), the magnetic filler is oriented if the volume of the magnetic filler is within a predetermined range. To do. As described above, by orienting the magnetic filler having a high metal content with high thermal conductivity, the heat transfer property of the urethane foam molded article can be greatly improved.

  Here, the iron alloy may contain a trace amount of additive of 0.05% by weight or less and impurities inevitable in production in addition to a metal and iron having a thermal conductivity of 150 W / (m · K) or more. Good.

  In the urethane foam molded article of the present invention, the magnetic filler in the substrate may be arranged in a predetermined direction with a certain regularity. For example, it may be arranged linearly between one end and the other end of the urethane foam molded body (not necessarily the end opposite to the one end by 180 °) or may be arranged in a curved shape. . Moreover, you may arrange | position radially from the center toward the outer periphery. Moreover, you may arrange | position in the shape which combined these shapes.

The method for producing a urethane foam molded article of the present invention comprises an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more, and the iron content x (wt%) in the iron alloy and The relationship between the volume y (mm ³ ) of the magnetic filler is point A (10, 0.25), point B (10, 0.01), point C (65, 0.0007), and point D in FIG. (90, 0.0007), a mixed material preparation step of preparing a mixed material by mixing a magnetic filler in a region surrounded by a point E (90, 0.25) and a foamed urethane resin raw material, A foam molding step of injecting the mixed material into the foam cavity and foam molding in a magnetic field having a substantially uniform magnetic flux density (corresponding to claim 7).

  In a conventional molding method using a magnetic field, magnetic force distribution in a cavity such as a foaming mold is not considered. For example, when molding is performed between opposing magnets, the lines of magnetic force that escape to the outside increase as the distance between the magnets increases. For this reason, a magnetic flux density becomes small along the diameter expansion direction of a magnet. Moreover, when the space | interval between magnets becomes large, it will be easy to produce a difference in magnetic flux density according to the distance with a magnet. Thus, it is difficult to apply a uniform magnetic field to the entire foaming raw material filled in the cavity. When the magnetic flux density is not uniform and foam molding is performed in a magnetic field with a magnetic field gradient, the magnetic filler in the foaming raw material moves in an unnecessary direction along the lines of magnetic force, and the desired orientation state cannot be obtained. . For this reason, in the manufactured urethane foam molding, desired heat transfer properties, sound absorption characteristics and the like cannot be obtained.

  According to the manufacturing method of the present invention, in the foam molding process, foam molding is performed in a magnetic field in which the magnetic flux density in the cavity is substantially uniform. For this reason, the uneven distribution of the magnetic filler due to the difference in magnetic flux density can be suppressed, and a desired orientation state can be obtained. Further, even when the blending amount of the magnetic filler is relatively small, the magnetic filler can be oriented in a substantially uniformly dispersed state. Therefore, according to the production method of the present invention, the urethane foam molded article of the present invention can be produced simply and at low cost.

  Hereinafter, embodiments of the urethane foam molded article and the method for producing the same according to the present invention will be described. The urethane foam molded article and the method for producing the same according to the present invention are not limited to the following embodiments, and various modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention. It can implement with the form of.

<Urethane foam molding>
As described above, the urethane foam molded article of the present invention has a base material made of polyurethane foam and a magnetic filler that is blended in the base material and is connected and oriented. The polyurethane foam is manufactured from foamed urethane resin raw materials such as a polyisocyanate component and a polyol component. Details will be described in the method for producing a urethane foam molded article of the present invention described later.

  The magnetic filler is made of an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more. The metal having a thermal conductivity of 150 W / (m · K) or more (hereinafter referred to as “high thermal conductivity metal” as appropriate) may be one kind or two or more kinds. The type of the high thermal conductivity metal is not particularly limited, and may be appropriately selected from copper, aluminum, silver, zinc, molybdenum and the like. Especially, it is desirable to employ | adopt 1 or more types chosen from copper, aluminum, and silver from the reason that heat conductivity is high and it is generally utilized widely as an industrial use. The thermal conductivities of copper, aluminum, and silver are 398 W / (m · K), 236 W / (m · K), and 420 W / (m · K) in this order.

Further, in the magnetic filler, the relationship between the iron content x (% by weight) in the iron alloy and the volume y (mm ³ ) of the magnetic filler is represented by points A (10, 0.25) and points in FIG. It is in a region surrounded by B (10, 0.01), point C (65, 0.0007), point D (90, 0.0007), and point E (90, 0.25).

  As shown in FIG. 1, the iron content in the iron alloy may be appropriately determined in the range of 10% by weight to 90% by weight according to the volume of the magnetic filler. From the viewpoint of increasing the heat transfer property improvement effect of the urethane foam molded article by increasing the content of the high thermal conductivity metal, the iron content is desirably 70% by weight or less. 50% by weight or less, more preferably 30% by weight or less is more preferable.

The volume of the magnetic filler, depending on the content of iron in the iron alloy in a range of 0.0007Mm ³ or 0.25 mm ³ or less, may be suitably determined. The smaller the volume of the magnetic filler, the better the dispersibility. Therefore, it is easy to obtain a desired alignment state.

  The shape of the magnetic filler is not particularly limited. For example, various shapes such as a fibrous shape, a columnar shape, a thin plate shape, a spherical shape, an elliptical spherical shape, and an oval spherical shape (a shape in which a pair of opposing hemispheres are connected by a cylinder) can be employed. When the magnetic filler has a shape other than a sphere, the oriented magnetic fillers are in contact with at least one of a line and a surface, not a point. For this reason, compared with the case where it contacts by a point, the contact area of magnetic fillers becomes large. As a result, a heat transfer path is easily secured and the amount of heat transferred is increased. Therefore, heat transfer property becomes higher. From the viewpoint of production cost, ease of production, etc., a fibrous magnetic filler is preferred. In the case of using a fibrous magnetic filler, the length in the longitudinal direction is preferably set to 0.1 mm or more and 5 mm or less in consideration of dispersibility and the like.

In the case of a magnetic filler having a shape other than a sphere, the aspect ratio of the magnetic filler is preferably 2 or more from the viewpoint of increasing the contact area between the magnetic fillers and improving the compatibility with the polyurethane foam. . In this specification, the aspect ratio is defined by the following equation (1).
Aspect ratio = b ² / (a · a ′) Expression (1)
In the formula (1), b represents the maximum length of the magnetic filler, a represents the length of the transverse side cross-section lateral side, and a ′ represents the length of the longitudinal axis longitudinal section. Here, “the length of the transverse side in the direction perpendicular to the axis” and “the length of the longitudinal side in the direction perpendicular to the axis” are determined as follows. That is, with the maximum length b of the magnetic filler as an axis, a quadrangle in which a cross-sectional shape in a direction perpendicular to the axis (axial direction) is inscribed is defined, and the lateral length when the quadrangle is viewed in plan is expressed as “axis The length “a” of the horizontal side of the cross section in the perpendicular direction is referred to as “the length a ′ of the vertical side of the cross section in the axial direction”. Hereinafter, specific shapes will be described.

  FIG. 2 shows the maximum length, the length of the transverse axis in the axial direction, and the length of the longitudinal side in the axial direction in each shape of the magnetic filler. In FIG. 2, (a) shows the case of a cylindrical shape, (b) shows the case of a thin plate, and (c) shows the case of a fiber. In addition, the shape shown to Fig.2 (a)-(c) is only an illustration, and a magnetic filler is not limited to these shapes. First, in the case of the columnar shape shown in (a), the length in the axial direction is the maximum length b. The cross-sectional shape in the direction perpendicular to the axis is a circle. The length in the horizontal direction of the quadrangle inscribed by the circle is “the length a ′ of the transverse side in the axial direction”, and the length in the longitudinal direction is “the length a ′ of the longitudinal side in the axial direction”. Next, in the case of the thin plate shape shown in (b), the longitudinal direction is the axial direction, and the length in the longitudinal direction is the maximum length b. Since the cross-sectional shape in the direction perpendicular to the axis is a rectangle, the length in the horizontal direction of this rectangle is “the length a of the transverse side in the direction perpendicular to the axis”, and the length in the vertical direction (corresponding to the thickness) is “direction perpendicular to the axis” The length of the vertical side of the cross section is a '". Next, in the case of the fibrous form shown in (c), the length in the axial direction is the maximum length b. The cross-sectional shape in the direction perpendicular to the axis is substantially an ellipse. However, in the case of the fibrous form (c), it has a shape like an “elongated barrel” having a large central portion in the longitudinal direction and small end portions. For this reason, in the full length in the longitudinal direction, the size of the cross section in the axial direction is not constant. That is, the cross-sectional area of the ellipse is different between the position α, the position β, and the position γ. In this case, the lateral length of the quadrilateral inscribed by the ellipse at the position β where the cross-sectional area is maximum is “the length a of the transverse side of the axial direction”, and the longitudinal length is “the longitudinal section of the axial direction”. The length of the vertical side a ′ ”.

  The magnetic filler may be manufactured by rolling, wire drawing, cutting, or the like after a high thermal conductivity metal and iron are blended at a predetermined ratio and an iron alloy ingot is cast. Further, it is desirable that the iron alloy is heat-treated in order to precipitate a large amount of a fine structure of a metal having a high thermal conductivity. It is considered that the heat conduction path increases and the thermal conductivity of the iron alloy becomes higher due to the precipitation of a large amount of the fine structure of the high thermal conductivity metal. As the heat treatment, for example, an aging treatment for holding at a temperature of 450 ° C. or higher and 500 ° C. or lower for 5 hours or longer is suitable. In particular, the holding time is more preferably 10 hours or longer.

  What is necessary is just to determine the compounding quantity of a magnetic filler suitably considering the improvement effect of heat conductivity, a sound absorption characteristic, cost, etc. For example, from the viewpoint of improving heat transferability, the blending amount of the magnetic filler is preferably 0.1% by volume or more when the volume of the urethane foam molded article is 100% by volume. It is more suitable when it is 1 volume% or more. On the other hand, it is desirable that the blending amount of the magnetic filler is 20% by volume or less in consideration of the dispersibility of the magnetic filler, the influence on the sound absorption characteristics, and the like. It is more suitable when it is 3 volume% or less.

  In addition, fine irregularities are present on the surface of the urethane foam molded article due to cell openings and foam-type mold surface transfer. For this reason, the contact area when it is brought into contact with the mating member is reduced, and the heat transfer performance is reduced accordingly. Therefore, even if the internal heat transferability is improved by the orientation of the magnetic filler, heat is not easily transferred to the counterpart member due to the poor surface condition. In order to solve such a problem, the glossiness of the heat transfer surface in the urethane foam molded article of the present invention is preferably 10% or more. The glossiness is more preferably 15% or more. Here, the heat transfer surface is a surface that contacts the mating member and transfers heat. The mating member may be a heating element or an endothermic body. The heat transfer surface is disposed so as to intersect the orientation direction of the magnetic filler. There may be one heat transfer surface or two or more heat transfer surfaces.

  The glossiness is measured according to JIS Z8741 (1997). That is, the specular gloss at an incident angle of 60 ° is expressed as 100% on a glass surface having a refractive index of a constant value of 1.567 over the entire visible wavelength range. In this specification, it is considered that the greater the glossiness, the smoother the surface of the heat transfer surface is.

  The heat transfer surface having a glossiness of 10% or more is smoother with less unevenness than the surface state of a normal urethane foam molded article. For this reason, the contact area (heat transfer area) between the heat transfer surface and the mating member increases, and the amount of heat transferred between both increases. For example, the heat transferred from the counterpart member to the heat transfer surface (one end) is transferred to the other end in the orientation direction mainly through the magnetic filler in the urethane foam molded body, and quickly radiated from the other end. Thus, according to the urethane foam molded article of this embodiment, the effect of improving the heat transfer property by the internal magnetic filler can be sufficiently exhibited without being hindered by the surface state of the heat transfer surface. As a result, the heat transferability of the entire urethane foam molded article can be further improved.

  By the way, if foaming urethane resin raw material is foam-molded in a sealed foaming mold, the foamed urethane resin raw material comes into contact with the mold surface of the foaming mold, and foaming is suppressed, thereby forming a high-density skin layer. The magnetic filler and cells generated by foaming are sealed by the skin layer and are not easily exposed on the surface. Therefore, it is desirable that the surface of the skin layer be a heat transfer surface. The thickness of the skin layer is not particularly limited, but may be, for example, 20 μm or less.

<Method for producing urethane foam molding>
The manufacturing method of the urethane foam molding of this invention has a mixed material preparation process and a foam molding process. Hereinafter, each step will be described.

(1) Mixed material preparation process This process consists of an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more, and the iron content x (wt%) in the iron alloy, The relationship with the volume y (mm ³ ) of the magnetic filler is that points A (10, 0.25), B (10, 0.01), C (65, 0.0007), D ( 90, 0.0007) and a magnetic filler in a region surrounded by point E (90, 0.25) and a foamed urethane resin raw material are mixed to prepare a mixed material. The magnetic filler is as described in the description of the foamed urethane molded article of the present invention. Therefore, the description is omitted here.

  The foamed urethane resin raw material may be prepared from already known raw materials such as a polyisocyanate component and a polyol component. Examples of the polyisocyanate component include tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, naphthalene diisocyanate, and derivatives thereof (for example, obtained by reaction with polyols). May be appropriately selected from among prepolymers, modified polyisocyanates and the like. Polyol components include polyhydric hydroxy compounds, polyether polyols, polyester polyols, polymer polyols, polyether polyamines, polyester polyamines, alkylene polyols, urea-dispersed polyols, melamine-modified polyols, polycarbonate polyols. It may be appropriately selected from the group of polymers, acrylic polyols, polybutadiene polyols, phenol-modified polyols and the like.

Furthermore, you may mix | blend a catalyst, a foaming agent, a foam stabilizer, a crosslinking agent, a flame retardant, an antistatic agent, a viscosity reducing agent, a stabilizer, a filler, a coloring agent, etc. suitably. For example, examples of the catalyst include amine-based catalysts such as tetraethylenediamine, triethylenediamine, and dimethylethanolamine, and organometallic catalysts such as tin laurate and tin octoate. Moreover, water is suitable as the foaming agent. In addition to water, methylene chloride, chlorofluorocarbon, CO ₂ gas and the like can be mentioned. Moreover, a silicone type foam stabilizer is suitable as the foam stabilizer, and triethanolamine, diethanolamine and the like are suitable as the crosslinking agent.

  Each of the foamed urethane resin raw material and the magnetic filler is weighed and mixed. The prepared mixed material is immediately subjected to the next foam molding step.

(2) Foam molding process This process is a process in which the mixed material prepared in the previous mixed material preparation process is injected into a foam mold cavity and foam-molded in a magnetic field having a substantially uniform magnetic flux density.

  As described above, it is desirable that the heat transfer surface of the urethane foam molded body be as smooth as possible in order to sufficiently exhibit the effect of improving the heat transfer performance by the magnetic filler. As a method of forming the heat transfer surface smoothly, for example, a method of foaming by applying a release agent such as silicone grease to the surface of the foaming mold is conceivable. However, when a release agent is used, the release agent adheres to the surface of the resulting urethane foam molded article, which may affect various characteristics such as sound absorption characteristics. In addition, the attached release agent may be deteriorated to cause problems. Further, the surface state of the heat transfer surface may be deteriorated due to uneven coating of the release agent. In addition, the manufacturing cost increases due to the material cost of the release agent and the addition of a coating process.

  In order to solve such a problem, for example, the surface roughness of at least the portion (the heat transfer surface molding die surface) for molding the heat transfer surface of the urethane foam molded body in the foam mold surface is 0.5 μm or less. Is desirable. Of course, the surface roughness of all mold surfaces in the foaming mold may be 0.5 μm or less. The surface roughness of the heat transfer surface molding die surface is more preferably 0.3 μm or less, and further preferably 0.1 μm or less. In this specification, the value of arithmetic average roughness (Ra) calculated based on JIS B0601 (2001) is employ | adopted as surface roughness.

  By setting the surface roughness of the heat transfer surface molding die surface in the foaming die to 0.5 μm or less, a smooth heat transfer surface with few irregularities can be formed. That is, for example, a urethane foam molded article having a heat transfer surface with a glossiness of 10% or more can be easily obtained. Moreover, since it is not necessary to use a mold release agent, there is no problem due to adhesion of the mold release agent described above.

  Such a foaming die can be obtained, for example, by subjecting the heat transfer surface molding die surface to a surface treatment such as polishing. Moreover, you may use the resin film for mold release. That is, a release resin film having a surface roughness of 0.5 μm or less may be disposed along the mold surface of the foaming mold so as to include at least the heat transfer surface mold surface. In this case, the heat transfer surface molding die surface is formed by the release resin film. If the resin film for mold release is used, the present foaming type can be used as it is. Further, it is not necessary to apply a release agent.

  The release resin film is preferably one that is difficult to adhere to the urethane foam molded article. Examples thereof include films of polyethylene terephthalate (PET), polyester, polyethylene (PE), polypropylene (PP), silicone resin, polytetrafluoroethylene (PTFE), and the like. The release resin film may be used by cutting a commercially available one or molding it into a predetermined mold surface shape by a known method such as vacuum molding, injection molding, blow molding or the like.

  The magnetic field may be formed in the direction in which the magnetic filler is oriented. For example, when the magnetic filler is oriented linearly, it is desirable that the magnetic lines of force in the foam-type cavity be formed substantially parallel from one end of the cavity to the other end. In this case, for example, magnets may be disposed in the vicinity of both surfaces of one end and the other end of the foaming mold so as to sandwich the foaming mold. A permanent magnet or an electromagnet may be used as the magnet. When an electromagnet is used, magnetic field formation can be switched on and off instantaneously, and the control of the magnetic field strength is easy. For this reason, it is easy to control foam molding. Here, it is desirable that the magnetic field lines constituting the magnetic field form a closed loop. By doing so, leakage of magnetic field lines is suppressed, and a stable uniform magnetic field can be formed in the cavity. In addition, in order to form a magnetic field inside a foaming mold with the magnet arrange | positioned outside the foaming mold, it is good to use a material with a low magnetic permeability, ie, a nonmagnetic material, as a foaming mold. For example, there is no problem as long as it is a foam type made of aluminum or aluminum alloy, which is usually used for polyurethane foam molding. In this case, the magnetic field and magnetic lines generated from a magnetic source such as an electromagnet are not easily affected, and the magnetic field state can be easily controlled. However, a magnetic material may be appropriately used according to the required magnetic field and magnetic field lines.

  In this step, the magnetic flux density in the cavity is substantially uniform. For example, the difference in magnetic flux density in the cavity is preferably within ± 10%. It is more preferable that it is within ± 5%, more preferably within ± 3%. By forming a uniform magnetic field in the foam cavity, uneven distribution of the magnetic filler can be suppressed, and a desired orientation state can be obtained. The foam molding may be performed with a magnetic flux density of 200 mT or more and 250 mT or less. By doing so, the magnetic filler in the mixed material can be surely oriented.

  It is desirable that the magnetic field be applied while the viscosity of the foamed urethane resin material is relatively low. When a foamed urethane resin material is thickened and a magnetic field is applied when foam molding is completed to some extent, it is difficult to obtain desired heat transfer characteristics and sound absorption characteristics because the magnetic filler is difficult to be oriented. In addition, it is not necessary to apply a magnetic field in all the time for performing foam molding.

  After foam molding is completed in this step, the mold is removed to obtain the urethane foam molded article of the present invention. At this time, a skin layer is formed on at least one of the one end and the other end of the urethane foam molded article depending on the manner of foam molding. The skin layer may be excised depending on the use (of course, it may not be excised).

  Next, the present invention will be described more specifically with reference to examples.

<Measurement of thermal conductivity>
(1) Manufacture of magnetic filler First, ingots of two types of iron alloys were cast while changing the blending ratio of copper and iron. One is copper: 30% by weight, iron: 70% by weight (sample No. 1), and the other is copper: 90% by weight, iron: 10% by weight (sample No. 2). Thereafter, the ingot was placed in a furnace maintained at a temperature of 450 ° C. or higher and 500 ° C. or lower, and an aging treatment was performed for about 10 hours. Next, the thermal conductivity of the manufactured iron alloy (sample No. 1) was measured. The thermal conductivity was measured by a laser flash method in accordance with JIS R1611. As a result, sample no. The thermal conductivity of the iron alloy No. 1 was 109 W / (m · K). In this way, sample no. 1 was confirmed to be higher than the thermal conductivity (14 W / (m · K)) of stainless steel (SUS430F).

From the two types of iron alloys, fibrous magnetic fillers having different sizes were produced. Table 1 shows the size and aspect ratio of the magnetic filler produced together with the iron and copper contents in the original iron alloy. In this example, the volume of the magnetic filler was calculated by regarding the shape of the magnetic filler as a cylindrical shape. That is, assuming that the diameter of the magnetic filler (the diameter of the portion where the cross-sectional area in the direction perpendicular to the longitudinal direction is the maximum) is d and the length is l, it is calculated by the following equation [volume = π (d / 2) ² × l]. did.

  As shown in Table 1, all of the magnetic fillers of Examples 1 to 3 are in a region (hatched region) surrounded by points A to E in FIG. On the other hand, the magnetic filler of Comparative Example 1 is outside the range of the same region.

(2) Production of urethane foam molded article and measurement of thermal conductivity A urethane foam molded article was produced using the produced magnetic filler. First, a foamed urethane resin raw material was prepared as follows. Polyether component polyether polyol (“S-0248” manufactured by Sumika Bayer Urethane Co., Ltd., average molecular weight 6000, number of functional groups 3, OH value 28 mg KOH / g) 100 parts by weight, crosslinking agent diethylene glycol (manufactured by Mitsubishi Chemical Corporation) 2 weights Parts, 2 parts by weight of foaming agent water, 1 part by weight of a tetraethylenediamine catalyst (“No. 31” manufactured by Kao) and a silicone foam stabilizer (“SZ-1313” manufactured by Nihon Unica) 0.5 A premix polyol was prepared by blending with parts by weight. Diphenylmethane diisocyanate (MDI) as a polyisocyanate component (“NE1320B” manufactured by BASFINOAC polyurethane, NCO = 44.8 wt%) was added to the prepared premix polyol and mixed to obtain a foamed urethane resin material. Here, the blending ratio of the polyol component and the polyisocyanate component (PO: ISO) was set to PO: ISO = 78.5: 21.5, with the total weight of both being 100%.

  Next, each prepared magnetic filler was mixed with the prepared foamed urethane resin raw material to obtain a mixed material. The blending amount of the magnetic filler was adjusted so as to be 1% by volume when the volume of the urethane foam molded article was 100% by volume in consideration of the expansion ratio, the weight of the foamed urethane resin raw material, the specific gravity of the magnetic filler, and the like. .

  Next, the mixed material was poured into an aluminum foaming mold (see FIGS. 3 and 4 to be described later. The cavity was a cylindrical shape having a diameter of 100 mm × thickness of 20 mm) and sealed. Subsequently, the foaming mold was installed in a magnetic field generator to perform foam molding. FIG. 3 shows a perspective view of the magnetic field generator. FIG. 4 shows a cross-sectional view of the magnetic field generator. As shown in FIGS. 3 and 4, the magnetic field generator 1 includes a pair of electromagnet parts 2U and 2D and a yoke part 3.

  The electromagnet part 2U includes a core part 20U and a coil part 21U. The core portion 20U is made of a ferromagnetic material and has a cylindrical shape extending in the vertical direction. The coil portion 21U is disposed on the outer peripheral surface of the core portion 20U. The coil portion 21U is formed by a conducting wire 210U wound around the outer peripheral surface of the core portion 20U. The conducting wire 210U is connected to a power source (not shown).

  The electromagnet portion 2D is disposed below the electromagnet portion 2U with the foaming mold 4 interposed therebetween. The electromagnet part 2D has the same configuration as the electromagnet part 2U. That is, the electromagnet part 2D includes a core part 20D and a coil part 21D. The coil portion 21D is formed by a conducting wire 210D wound around the outer peripheral surface of the core portion 20D. The conducting wire 210D is connected to a power source (not shown).

  The yoke portion 3 has a C shape. The C-shaped upper end of the yoke part 3 is connected to the upper end of the core part 20U of the electromagnet part 2U. On the other hand, the C-shaped lower end of the yoke part 3 is connected to the lower end of the core part 20D of the electromagnet part 2D.

  The foaming mold 4 includes an upper mold 40U and a lower mold 40D. The foaming mold 4 is interposed between the core part 20U of the electromagnet part 2U and the core part 20D of the electromagnet part 2D. The upper mold 40U has a prismatic shape. A cylindrical concave portion is formed on the lower surface of the upper mold 40U. Similarly, the lower mold 40D has a prismatic shape. A cylindrical recess is formed on the upper surface of the lower mold 40D. The upper mold 40U and the lower mold 40D are arranged so that the openings of the recesses face each other. A cavity 41 is defined between the upper mold 40U and the lower mold 40D by combining the concave portions. As described above, the cavity 41 is filled with the mixed material.

  When both the power source connected to the conducting wire 210U and the power source connected to the conducting wire 210D are turned on, the upper end of the core portion 20U of the upper electromagnet portion 2U is magnetized to the S pole and the lower end is magnetized to the N pole. For this reason, magnetic force lines L (indicated by dotted lines in FIG. 4) are generated in the core portion 20U from the upper side to the lower side. Further, the upper end of the core portion 20D of the lower electromagnet portion 2D is magnetized to the S pole and the lower end is magnetized to the N pole. For this reason, lines of magnetic force L are generated in the core portion 20D from the upper side to the lower side. Further, the lower end of the core portion 20U is an N pole, and the upper end of the core portion 20D is an S pole. For this reason, lines of magnetic force L are generated from above to below between the core portion 20U and the core portion 20D. As described above, lines of magnetic force L are generated between the electromagnet portions 2U and 2D from the top to the bottom. The lines of magnetic force L radiated from the lower end of the core part 20D of the lower electromagnet part 2D flow through the yoke part 3 and flow into the upper end of the core part 20U of the upper electromagnet part 2U. Thus, since the magnetic force line L comprises a closed loop, the leakage of the magnetic force line L can be suppressed.

  As described above, the foaming mold 4 is interposed between the core portion 20U and the core portion 20D. For this reason, a uniform magnetic field is formed in the cavity 41 of the foaming mold 4 by lines of magnetic force L that are substantially parallel from the top to the bottom. After the foaming mold 4 was installed in the magnetic field generator 1, foaming was performed while applying a magnetic field for the first approximately 2 minutes. For the next approximately 5 minutes, foam molding was performed without applying a magnetic field.

After the foam molding was completed, the mold was removed to obtain a urethane foam molded article. The obtained urethane foam moldings were numbered as Examples 1 to 3 and Comparative Example 1, respectively, corresponding to the magnetic filler numbers in Table 1 above. On the other hand, as a magnetic filler, a fiber made of stainless steel (SUS430F) (“KC Metal Fiber SUS430F” manufactured by Niji Gisha Co., Ltd .: diameter of about 30 μm, length of about 2 mm, volume of 0.001414 mm ³ , aspect ratio of 4444) is used. Similarly, foam molding was performed. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 2. In addition, the compounding quantity of the magnetic filler in the urethane foam moldings of Examples 1 to 3 and Comparative Examples 1 and 2 is 1% by volume when the volume of the urethane foam molding is 100% by volume.

  When the manufactured urethane foam molding was observed visually, in the urethane foam moldings of Examples 1 to 3 and Comparative Example 2, the magnetic fillers were all connected and oriented. On the other hand, in the urethane foam molding of Comparative Example 1, the magnetic filler was only dispersed but not oriented.

  Moreover, the heat conductivity of the urethane foam molded article of Example 1 and the urethane foam molded article of Comparative Example 2 was measured. The thermal conductivity was measured by a disk heat flow meter method based on ASTM E-1530. As a result, the thermal conductivity of the urethane foam molding of Example 1 was 0.4 W / (m · K), whereas the thermal conductivity of the urethane foam molding of Comparative Example 2 was 0.00. It was 26 W / (m · K). That is, when a predetermined magnetic filler made of an iron alloy containing copper was used, the thermal conductivity was about 1.5 times that of the case using a stainless steel magnetic filler. From the above, it has been confirmed that by orienting the magnetic filler in the region surrounded by the points A to E in FIG.

<About thermal conductivity improvement effect by heat treatment>
Changes in thermal conductivity of cast iron alloys due to heat treatment were investigated. First, two types of iron alloy ingots having different mixing ratios of copper and iron were cast. One is 21.33% by weight of copper and 78.67% by weight of iron (sample No. 3), and the other is 48.42% by weight of copper and 51.58% by weight of iron (sample). No. 4). And the heat conductivity of the iron alloy after casting was measured. The thermal conductivity was measured by a laser flash method in accordance with JIS R1611. Next, each iron alloy was placed in a furnace maintained at a temperature of 450 ° C. or higher and 500 ° C. or lower, and an aging treatment was performed for about 10 hours. Thereafter, similarly, the thermal conductivity of the iron alloy was measured. FIG. 5 shows the measurement results of the thermal conductivity of each iron alloy after casting and after aging treatment.

  As shown in FIG. 5, in any iron alloy, the thermal conductivity was higher after the aging treatment. In particular, No. 1 with a high copper content. The increase in thermal conductivity of the iron alloy No. 4 was larger.

  Further, the structure of each iron alloy after casting and after aging treatment was observed. 6 to 9 show photographs of the alloy structure. FIG. 3 is a photograph of the alloy structure after casting (the photograph on the left is 100 times magnification, and the photograph on the right is 500 times magnification (same in FIGS. 7 to 9)). FIG. 3 is an alloy structure photograph after aging treatment of No. 3; FIG. 4 is a photograph of an alloy structure after casting of No. 4; FIG. 4 is an alloy structure photograph after aging treatment of No. 4;

  6-9, the copper structure is shown in white. When FIG. 6 and FIG. 7 or FIG. 8 and FIG. 9 are compared, it can be seen that the amount of deposited copper is increased by the aging treatment. Therefore, it is considered that the thermal conductivity is increased by increasing the amount of copper deposited by the aging treatment and expanding the heat propagation path.

  The urethane foam molded article of the present invention can be used for various applications in the field of automobiles and the like. For example, soundproof tires for reducing noise caused by road surface irregularities, engine covers and side covers arranged in the engine room of vehicles to reduce engine noise, and sound absorbing materials such as ceilings and pillars in vehicle interiors It is suitable for sound absorbing materials for motors of office automation (OA) equipment and home appliances, heat radiating sound absorbing materials for electronic devices such as personal computers, and sound absorbing materials for inner and outer walls of houses.

It is a graph which shows the relationship between content (weight%) of iron in an iron alloy, and the volume (mm < ³ >) of a magnetic filler about the magnetic filler contained in the urethane foam molding of this invention. It is explanatory drawing about the maximum length in each shape of a magnetic filler, the length of an axial direction cross-section horizontal side, and the length of an axial direction cross-section vertical side. In an Example, it is a perspective view of the magnetic field generator used for manufacture of a urethane foam molding. It is sectional drawing of the magnetic field generator. It is a graph which shows the measurement result of the heat conductivity of the iron alloy after casting and after an aging treatment. Sample No. 3 is a photograph showing the alloy structure of 3 after casting. Sample No. 3 is a photograph showing the alloy structure after aging treatment of No. 3. Sample No. 4 is a photograph showing an alloy structure after casting of No. 4; Sample No. 4 is a photograph showing an alloy structure after aging treatment of No. 4;

Explanation of symbols

1: Magnetic field generator 2U, 2D: Electromagnet part 20U, 20D: Core part 21U, 21D: Coil part 210U, 210D: Conductor 3: Yoke part 4: Foaming mold 40U: Upper mold 40D: Lower mold 41: Cavity L: Magnetic field line

Claims (9)

A base material made of polyurethane foam, and a magnetic filler blended in the base material and aligned and connected to each other,
The magnetic filler is made of an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more,
The relationship between the iron content x (% by weight) in the iron alloy and the volume y (mm ³ ) of the magnetic filler is shown by points A (10, 0.25) and B (10, 0) in FIG. .01), point C (65, 0.0007), point D (90, 0.0007), and within a region surrounded by point E (90, 0.25), a urethane foam molded article characterized by .   The urethane foam molded article according to claim 1, wherein the metal contained in the iron alloy is at least one selected from copper, aluminum, and silver.   The urethane foam molded article according to claim 1 or 2, wherein the iron alloy is subjected to an aging treatment for holding at a temperature of 450 ° C or higher and 500 ° C or lower for 5 hours or longer.   The urethane foam molded article according to any one of claims 1 to 3, wherein an iron content in the iron alloy is 70% by weight or less.   The urethane foam molded article according to any one of claims 1 to 4, wherein the magnetic filler has a fibrous shape.   6. The urethane foam molding according to claim 1, wherein the blending amount of the magnetic filler is 0.1 volume% or more and 20 volume% or less when the volume of the urethane foam molded body is 100 volume%. body. It consists of an iron alloy of iron and a metal having a thermal conductivity of 150 W / (m · K) or more, and the iron content x (wt%) in the iron alloy and the volume y (mm ³ ) of the magnetic filler The relationships are point A (10, 0.25), point B (10, 0.01), point C (65, 0.0007), point D (90, 0.0007), and point E (90 in FIG. , 0.25), a mixed material preparation step of preparing a mixed material by mixing the magnetic filler in the region surrounded by the foamed urethane resin raw material,
A foam molding process in which the mixed material is injected into a cavity of a foam mold, and foam molding is performed in a magnetic field having a substantially uniform magnetic flux density;
The manufacturing method of the urethane foam molding which has this.   The method for producing a urethane foam molded article according to claim 7, wherein the difference in magnetic flux density in the cavity is within ± 10%.   The method for producing a urethane foam molded article according to claim 7 or 8, wherein the magnetic flux density during foam molding is 200 mT or more and 250 mT or less.