JP5577065B2 - Urethane foam molding and method for producing the same - Google Patents

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 (see, for example, Patent Document 1). The urethane foam molded article has a large number of cells (bubbles) inside. For this reason, the thermal conductivity of the urethane foam molding is small. Therefore, when it arrange | positions around an engine, a motor, etc. with a heat_generation | fever, heat | fever accumulates in a urethane foam molding, and there exists a possibility of causing the temperature rise of an engine, a motor, etc. In order to solve such a problem, it is necessary to improve the heat dissipation of the urethane foam molded article. For example, Patent Documents 2 and 3 disclose urethane foam molded articles having oriented magnetic particles.

JP 2003-97645 A JP 2007-230544 A JP 2009-51148 A

  When the magnetic particles in the polyurethane foam are oriented in a state of being connected to each other as in the urethane foam molded products disclosed in Patent Documents 2 and 3, a heat transfer path is formed in the orientation direction of the magnetic particles. The Thereby, the heat dissipation of a urethane foam molded object improves. Here, 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, iron, stainless steel or the like having excellent magnetization characteristics is used for the magnetic particles. However, the thermal conductivity of iron and stainless steel is small. For this reason, even if these magnetic particles are oriented, it is difficult to improve the heat dissipation of the urethane foam molded body to a satisfactory level.

  From the viewpoint of improving heat dissipation, it is considered effective to contain fillers having high thermal conductivity in the urethane foam molded body in a state of being connected to each other. Examples of the filler having a high thermal conductivity include carbon fiber. However, carbon fiber is a non-magnetic material. For this reason, carbon fibers are difficult to be oriented in a magnetic field. Therefore, unlike the magnetic particles, the heat transfer path cannot be formed by connecting the carbon fibers by foam molding in a magnetic field. Therefore, even if a urethane foam molded article is produced by blending carbon fibers, the heat dissipation effect by the carbon fibers cannot be sufficiently exhibited.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the urethane foam molded object which has a desired sound absorption characteristic, and high heat conductivity, and its manufacturing method.

  (1) In order to solve the above-mentioned problem, the urethane foam molded article of the present invention has a foam main body made of a polyurethane foam in which a skeleton resin partitioning a cell extends in a streak shape from one end to the other end, The skeleton resin contains magnetic particles oriented in the direction from the one end to the other end, and a highly thermally conductive filler made of a non-magnetic material and connected to each other in the direction from the one end to the other end. It is characterized by.

  Unlike the normal polyurethane foam having a cell structure having no directionality, the foam main body in the urethane foam molded article of the present invention is a polyurethane in which the skeletal resin defining the cells extends in a streak shape from one end to the other end. It consists of a form. Here, “one end” and “the other end” do not necessarily have to face each other by 180 °. That is, the skeleton resin may extend in a straight line or a curved line between one end and the other end. Moreover, you may extend radially toward the outer periphery from the center. Moreover, you may extend in the shape which combined these shapes.

  The skeleton resin contains magnetic particles and a high thermal conductive filler. The thermal conductivity of the high thermal conductive filler is large. However, the high thermal conductive filler is made of a nonmagnetic material. Therefore, it is difficult to align in a magnetic field. For this reason, it is difficult to originally contain a highly thermally conductive filler made of a non-magnetic material in the skeleton resin in a state along a certain direction. In this regard, the urethane foam molded article of the present invention utilizes the magnetic field orientation of the magnetic particles. That is, when a magnetic field directed from one end to the other end is applied during molding of the foam main body, the magnetic particles contained in the resin raw material are oriented along the lines of magnetic force. Along with the orientation of the magnetic particles, the resin flows so as to be rolled, and a skeleton that extends in a streak shape in the direction of the magnetic field, that is, from one end to the other end is constructed. At this time, the highly thermally conductive filler contained in the resin raw material together with the magnetic particles also moves as if oriented from one end to the other end due to the flow of the resin. As a result, the high thermal conductive fillers are arranged in the skeleton resin in a state where they are connected to each other from one end to the other end.

  Thus, the urethane foam molded article of the present invention has high thermal conductivity due to the action of the high thermal conductive filler arranged in the skeleton resin. That is, the heat applied to one end of the urethane foam molded article of the present invention is transmitted to the other end in the alignment direction via the high thermal conductive filler, and is quickly released from the other end. Therefore, according to the urethane foam molded article of the present invention, it is possible to effectively suppress an increase in the temperature of the sound absorbing object serving as a heat source.

  Further, as is clear from the examples described later, it has also been confirmed that the urethane foam molded article of the present invention exhibits high sound absorption in a specific frequency region. Thus, the urethane foam molded article of the present invention has both high thermal conductivity and desired sound absorption characteristics.

  (2) The method for producing a urethane foam molded article according to the present invention is a method for producing a urethane foam molded article having the constitution (1) above, and is a high heat comprising a foamed urethane resin raw material, magnetic particles, and a non-magnetic substance. A raw material mixing step of mixing conductive fillers into a mixed raw material, and a foaming step of injecting the mixed raw material into a foaming cavity and foaming in a magnetic field from one end of the cavity to the other. It is characterized by having.

  According to the production method of the present invention, the urethane foam molded article of the present invention can be easily produced. That is, in the production method of the present invention, as described above, a urethane foam molded article is produced using the magnetic field orientation of the magnetic particles. Hereinafter, the reaction in the foaming step will be described in detail. FIG. 1 shows a model of a part of the reaction in the foaming process. In addition, the magnitude | size, shape, etc. of the magnetic body particle | grains and highly heat conductive filler in this invention are not limited at all by FIG.

  As shown in FIG. 1A, the mixed raw material 9 is a mixture of a foamed urethane resin raw material 90, magnetic particles 91, and a high thermal conductive filler 92. In the foaming step, bubbles 93 are generated in the mixed raw material 9. Usually, the surface of the bubble 93 film (foam film) 930 is stabilized by the foam stabilizer 900 contained in the foamed urethane resin raw material 90. However, the mixed raw material 9 contains magnetic particles 91. The magnetic particles 91 enter the foam film 930. The magnetic particles 91 have a bubble breaking action. Therefore, as shown in FIG. 1B, the bubbles 93 are destroyed by the magnetic particles 91 that have entered the bubble film 930. At this time, as shown by white arrows in FIG. 1B, when a magnetic field is applied from the bottom to the top, the magnetic particles 91 are oriented in the vertical direction. Along with the orientation of the magnetic particles 91, the foam film 930 flows so as to be rolled up and down, and the skeleton of the foam main body is constructed. As the foam film 930 flows, the high thermal conductive filler 92 also moves so as to align in the vertical direction. Thus, the high thermal conductive fillers 92 are arranged in the skeleton resin in a state where they are connected to each other in the vertical direction.

  According to the present invention, it is possible to provide a urethane foam molded article having desired sound absorption characteristics and high thermal conductivity, and a simple manufacturing method thereof.

It is a model figure which shows a part of reaction of the foaming process in the manufacture process of the urethane foam molding of this invention. 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 SEM photograph of the axial direction (magnetic field direction) cross section of the urethane foam molding of Example 1. It is the SEM photograph which expanded a part of frame resin in the section. It is a SEM photograph of the axial direction cross section of the urethane foam molded article of Comparative Example 2. It is the SEM photograph which expanded a part of frame resin in the section. It is a graph which shows the measurement result of the heat conductivity of the urethane foam molding of Example 1 and Comparative Examples 1-5. It is a graph which shows the measurement result of the sound absorption rate of the urethane foam molding of Example 1 and Comparative Example 1.

  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>
The urethane foam molded article of the present invention has a foam main body made of a polyurethane foam in which a skeleton resin partitioning a cell extends in a streak shape from one end to the other end. Magnetic particles oriented in the direction of the other end and high thermal conductive fillers made of a non-magnetic material and connected to each other in the direction of the other end from the one end are contained.

  The structure of the skeleton resin of the foam main body can be confirmed, for example, by observing the cross section of the foam main body with a scanning electron microscope (SEM). Moreover, the urethane foam molded article of the present invention may have a cell-free skin layer on at least one of one end and the other end of the foam main body. The skin layer can be formed by, for example, foam-molding in a sealed foaming mold, bringing the foamed urethane resin raw material into contact with the foamed inner wall, and suppressing foaming. Moreover, the urethane resin member used as an outer skin layer may be previously installed in a foaming type, and the foaming urethane resin raw material may be foam-molded.

The magnetic particles contained in the skeleton resin may be those having excellent magnetization characteristics. For example, ferromagnetic materials such as iron, nickel, cobalt, gadolinium, and stainless steel, MnO, Cr ₂ O ₃ , FeCl ₂ , MnAs Antiferromagnetic materials such as these, and particles of alloys using these are suitable. Among these, iron powder and the like are preferable from the viewpoint of easy availability as fine particles.

  The size of the magnetic particles may be determined in consideration of the dispersibility, the orientation, the bubble breaking action during the foaming reaction, and the like. For example, it is desirable that the particle diameter of the magnetic particles be 100 μm or less. From the viewpoint of improving dispersibility and orientation, and breaking the foam film to construct a desired skeleton, the particle diameter of the magnetic particles is preferably small. For example, 50 μm or less, 20 μm or less, and further 10 μm or less are preferable. In addition, from the viewpoint of easy availability, the particle diameter of the magnetic particles is preferably 0.1 μm or more. Here, the maximum particle length is defined as the particle diameter.

  The shape of the magnetic particles is not particularly limited. For example, from the viewpoint of easy dispersion and easy penetration into the foam film during the foaming reaction, it is desirable to employ spherical (true spherical and substantially spherical) particles.

  The content of the magnetic particles is 0.5% by volume or more when the volume of the foamed body is 100% by volume (hereinafter the same in content) from the viewpoint of building a skeleton by flowing the resin by orientation. It is desirable to do. It is more suitable when it is 1 volume% or more. On the other hand, in consideration of the influence on the foaming reaction, cost, and the like, the content of the magnetic particles is preferably 10% by volume or less. It is more suitable when it is 5 volume% or less.

  The high thermal conductive filler contained in the skeleton resin may be a non-magnetic material having a high thermal conductivity. In the present specification, diamagnetic materials and paramagnetic materials other than the ferromagnetic materials and antiferromagnetic materials are referred to as nonmagnetic materials. For example, the thermal conductivity of the high thermal conductive filler is desirably 300 W / m · K or more. It is more preferable that it is 500 W / m · K or more. As the high thermal conductive filler, for example, a carbon material, copper, aluminum, and an alloy based on these can be used.

  The shape of the high thermal conductive filler is not particularly limited. For example, various shapes such as a fibrous shape, a scaly shape, a columnar shape, a spherical shape, an elliptical spherical shape, and an elliptical spherical shape (a shape in which a pair of opposing hemispheres are connected by a cylinder) can be employed. When the high thermal conductive filler has a shape other than a sphere, the high thermal conductive 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 at a point, the contact area of highly heat conductive fillers becomes large. As a result, a heat transfer path is easily secured and the amount of heat transferred is increased. For example, a fibrous filler such as carbon fiber is preferable from the viewpoint of manufacturing cost, ease of manufacturing, and the like.

  The size (maximum length) of the high thermal conductive filler may be determined in consideration of the dispersibility, the size of the foam body to be manufactured, and the like. For example, one having a maximum length of 500 μm or less may be used.

  The content of the high thermal conductive filler may be determined in consideration of the influence on the foaming reaction, the effect of improving thermal conductivity, and the like. For example, in order to obtain a foamed body that does not inhibit the foaming reaction and satisfies the desired sound absorption characteristics, the content of the high thermal conductive filler is desirably 10% by volume or less. It is more suitable when it is 5 volume% or less. On the other hand, in order to obtain the effect of improving thermal conductivity, the content of the high thermal conductive filler is preferably 0.5% by volume or more. It is more suitable when it is 1 volume% or more.

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

(1) Raw material mixing step This step is a step of mixing a foamed urethane resin raw material, magnetic particles, and a high thermal conductive filler made of a non-magnetic material to obtain a mixed raw material.

  The foamed urethane resin raw material may be prepared from already known raw materials such as polyol and polyisocyanate. Polyols include polyhydric hydroxy compounds, polyether polyols, polyester polyols, polymer polyols, polyether polyamines, polyester polyamines, alkylene polyols, urea-dispersed polyols, melamine-modified polyols, polycarbonate polyols, acrylics What is necessary is just to select suitably from polyols, polybutadiene polyols, phenol modified polyols, etc. Examples of the polyisocyanate include tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, naphthalene diisocyanate, and derivatives thereof (for example, by reaction with polyols). What is necessary is just to select suitably from prepolymers obtained, modified polyisocyanate, etc.).

In addition, 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 colorant, and the like may be appropriately added to the foamed urethane resin raw material. 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. Other than 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.

  The type, size, shape, and content of the magnetic particles are as described in the description of the urethane foam molded body of the present invention. As the mixed raw material, magnetic particles may be used as they are, such as the above iron powder, but a dispersion in which magnetic particles are dispersed in a solvent may be used. Examples of such a dispersion include a magnetorheological fluid (Magnetorheological fluid; MR fluid) containing micron-sized magnetic particles and a microfluid (Magnetic fluid; MF) containing nanosized magnetic particles. Examples thereof include a magnetic compound fluid (MCF) in which magnetic particles of a size are mixed. The magnetic mixed fluid (MCF) referred to here is, for example, a particle-dispersed mixed functional fluid described in Japanese Patent Application Laid-Open No. 2002-170791. Specifically, a product “E-600” manufactured by Sigma High Chemical Co., a product “MRF-122-2ED”, “MRF-132DG”, “MRF-140CG” manufactured by Lord, etc. can be used.

  The kind, size, shape and content of the high thermal conductive filler are as described in the description of the foamed urethane molded article of the present invention. Therefore, the description is omitted here.

  The mixing in this step can be performed by mechanically stirring the foamed urethane resin raw material, the magnetic particles, and the high thermal conductive filler using a propeller or the like. In addition, magnetic particles and a high thermal conductive filler are appropriately added to the components of the foamed urethane resin raw material to prepare two types of raw materials (polyol raw material and polyisocyanate raw material) in advance, By injecting at high pressure, the raw materials may collide with each other.

  In the case of employing the latter collision stirring method, this process is carried out in such a manner that the foamed urethane resin raw material comprises a polyol raw material containing a polyol and a polyisocyanate raw material containing a polyisocyanate, and the magnetic particles and the high thermal conductive filler It is blended and prepared in at least one of a polyol raw material and the polyisocyanate raw material, and the polyol raw material and the polyisocyanate raw material are mixed by jetting each other at high pressure to form the mixed raw material. can do. According to this configuration, continuous production becomes possible. Therefore, this configuration is suitable for mass production. Moreover, according to this structure, compared with the method of stirring mechanically, the washing | cleaning process of the container required for every mixing becomes unnecessary, and a yield improves. Therefore, the manufacturing cost can be reduced.

  In this configuration (collision stirring method), a polyol raw material and a polyisocyanate raw material, in which magnetic particles and a high thermal conductive filler are blended in advance, are each injected at high pressure from the injection holes provided in the mixing head of the high pressure foaming apparatus. And collide. As described above, the particle diameter of the magnetic particles is preferably 100 μm or less from the viewpoint of being oriented during the foaming reaction and breaking the foam film to construct a desired skeleton. In addition, the maximum length of the high thermal conductive filler is desirably 500 μm or less. If the size of the magnetic particles and the high thermal conductive filler is larger than the diameter of the injection holes, the injection holes are likely to be damaged due to contact of the magnetic particles and the like. Thereby, there exists a possibility that durability of a mixing head may fall. Moreover, the larger the size of the magnetic particles and the high thermal conductive filler, the more easily the magnetic particles and the high thermal conductive filler settle in the polyol raw material. For this reason, uniform mixing is difficult. Therefore, when the collision stirring method is employed, it is desirable that the maximum lengths of the magnetic particles and the high thermal conductive filler are smaller than the diameters of the injection holes through which the polyol raw material and the polyisocyanate raw material are injected. By doing so, it is possible to reduce the load on the mixing head and extend the life of the high-pressure foaming apparatus. Moreover, sedimentation of the magnetic particles and the high thermal conductive filler is suppressed, and an increase in viscosity in the polyol raw material can be reduced.

(2) Foaming step This step is a step in which the mixed raw material obtained in the previous raw material mixing step is injected into a foaming cavity and foamed in a magnetic field from one end of the cavity to the other. For example, when foaming is performed in a magnetic field in which the lines of magnetic force are substantially parallel from one end of the cavity to the other end, the skeleton resin of the foam main body extends substantially linearly from one end to the other end. In order to form such a magnetic field, for example, magnets may be disposed near 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. Therefore, it is easy to control foam molding.

  Moreover, 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 magnetic field can be formed in the cavity. In order to form a magnetic field inside the foaming mold with a magnet disposed outside the foaming mold, it is preferable to use a material having a low magnetic permeability, that is, a nonmagnetic material. 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 foaming mold made of a magnetic material may be used as appropriate according to the required magnetic field and magnetic field lines.

  It is desirable that the magnetic field be applied while the viscosity of the foamed urethane resin material is relatively low. If a foamed urethane resin raw material is thickened and a magnetic field is applied when foam molding is completed to some extent, the magnetic particles are difficult to be oriented, so that a desired skeleton cannot be constructed. In addition, it is not necessary to apply a magnetic field in all the time for performing foam molding.

  For example, when foam molding is performed using a pair of opposing magnets without considering the magnetic force distribution in the cavity, the lines of magnetic force that escape to the outside increase as the outer periphery of the magnet is closer. 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. If foam molding is performed in a magnetic field with a non-uniform magnetic flux density and a magnetic field gradient, the magnetic particles in the mixed raw material move in unnecessary directions along the lines of magnetic force, making it difficult to obtain a desired skeleton. Therefore, it is desirable that the magnetic flux density of the magnetic field be substantially the same in the magnetic force direction from one end of the cavity to the other end and in the direction perpendicular to the magnetic force direction. That is, it is desirable that 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%.

  After foam molding is completed in this step, the mold is removed to obtain the urethane foam molded article of the present invention. Under the present circumstances, the skin layer may be formed in at least one of the one end and other end of a foam main body by the method 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.

<Manufacture of urethane foam molding>
[Example 1]
First, polyether polyol (“S-0248” manufactured by Sumika Bayer Urethane Co., Ltd., average molecular weight 6000, functional group number 3, OH value 28 mg KOH / g) 100 parts by weight, and diethylene glycol (manufactured by Mitsubishi Chemical Corporation) as a crosslinking agent 2 parts by weight 2 parts by weight of water as a foaming agent, 1 part by weight of a tetraethylenediamine catalyst (“No. 31” manufactured by Kao Corporation), and 0.5 weight of a silicone foam stabilizer (“SZ-1313” manufactured by Nihon Unica) And a polyol raw material was prepared. Moreover, diphenylmethane diisocyanate (MDI) (“NE1320B” manufactured by BASFINOAC polyurethane, NCO = 44.8 wt%) was prepared as a polyisocyanate raw material. The polyol raw material and the polyisocyanate raw material were prepared so that PO: MDI = 78.5: 21.5 when the total weight of the polyether polyol (PO) and MDI was 100%.

  Next, iron powder (“HQ grade” manufactured by BASF Japan Ltd .; diameter 1.1 μm, thermal conductivity 70 W / m · K) as magnetic particles and carbon fiber as a high thermal conductive filler are added to the prepared polyol raw material. (“Raheama (registered trademark), R-A301” manufactured by Teijin Ltd.); average fiber diameter of 8 μm, length of 200 μm, thermal conductivity of 600 W / m · K) was added. The blending amounts of iron powder and carbon fiber were both 1% by volume when the volume of the urethane foam molded article to be produced was 100% by volume.

  Subsequently, the polyol raw material containing iron powder and carbon fibers and the polyisocyanate raw material were mixed by being injected and collided with each other at high pressure from the injection holes arranged to face the mixing head of the high pressure foaming apparatus.

  The mixed raw material obtained by the collision stirring was poured into an aluminum foaming mold (see FIGS. 2 and 3 to be described later. The cavity was a cylinder 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. 2 is a perspective view of the magnetic field generator. FIG. 3 shows a cross-sectional view of the magnetic field generator. As shown in FIGS. 2 and 3, the magnetic field generation device 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 raw 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 (shown by dotted lines in FIG. 3) 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. Specifically, the magnetic flux density in the cavity 41 was about 200 mT. Further, the difference in magnetic flux density in the cavity 41 was within ± 3%. 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 cylindrical urethane foam molded body. The obtained urethane foam molded article was used as the urethane foam molded article of Example 1.

[Comparative Example 1]
The polyol raw material and the polyisocyanate raw material before adding the iron powder and the carbon fiber are mixed by being injected and collided from the injection holes of the mixing head, respectively, in the same manner as in Example 1. A foamed urethane resin material was used. The obtained foamed urethane resin material was subjected to foam molding without applying a magnetic field. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 1.

[Comparative Example 2]
Only carbon fiber (same as above) was added to the polyol raw material. The blending amount of the carbon fiber was 1% by volume as in Example 1. In the same manner as in Example 1, the polyol raw material containing only carbon fibers and the polyisocyanate raw material were each mixed by being injected and collided from the injection holes of the mixing head. The obtained mixed raw material was foam-molded without applying a magnetic field. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 2.

[Comparative Example 3]
Only iron powder (same as above) was added to the polyol raw material. The amount of iron powder was 1% by volume, as in Example 1. In the same manner as in Example 1, the polyol raw material containing only iron powder and the polyisocyanate raw material were mixed by being injected and collided from the injection holes of the mixing head, respectively. The obtained mixed raw material was foam-molded without applying a magnetic field. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 3.

[Comparative Example 4]
In the same manner as in Example 1, the mixed raw material of Comparative Example 3 was subjected to foam molding in a magnetic field to produce a urethane foam molded article. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 4.

[Comparative Example 5]
The mixed raw material of Example 1 was foam-molded without applying a magnetic field. The obtained urethane foam molded article was used as the urethane foam molded article of Comparative Example 5.

<SEM observation of urethane foam molding>
The cross sections of the urethane foam moldings produced in Example 1 and Comparative Example 2 were observed with a scanning electron microscope (SEM). 4 is an SEM photograph of an axial (magnetic field) cross section of the urethane foam molded article of Example 1. FIG. FIG. 5 is an SEM photograph in which a part of the skeleton resin in the cross section is enlarged. 6 is an SEM photograph of an axial cross section of the urethane foam molded article of Comparative Example 2. FIG. FIG. 7 is an SEM photograph in which a part of the skeleton resin in the cross section is enlarged.

  As shown in FIG. 4, in the urethane foam molded article of Example 1, the skeleton resin that partitions the cells extends in a streak shape in the magnetic field direction (vertical direction). On the other hand, as shown in FIG. 6, in the urethane foam molded article of Comparative Example 2, the skeleton resin is formed in a mesh shape, and regularity is not seen in the extending direction of the skeleton resin. This difference is due to the presence or absence of iron powder (magnetic particles). That is, the urethane foam molded body of Example 1 is manufactured from a mixed raw material containing iron powder in addition to carbon fibers. For this reason, at the time of foam molding in a magnetic field, as the iron powder is oriented along the lines of magnetic force, the resin flows and the skeleton as shown in FIG. 4 is constructed.

  Further, according to FIG. 5, it can be confirmed that the iron powder is aligned in the magnetic field direction in the skeleton resin of the urethane foam molded article of Example 1. In addition, carbon fiber is also contained in the skeleton resin. However, it is thought that carbon fiber overlaps with iron powder. Therefore, in FIG. 5, the carbon fibers could not be visually recognized separately from the iron powder. On the other hand, according to FIG. 7, it can be confirmed that carbon fiber is contained in the skeleton resin of the urethane foam molded article of Comparative Example 2. However, the directions of the carbon fibers are various and are not connected to each other in the vertical direction.

<Measurement of thermal conductivity>
The thermal conductivity of the urethane foam molded articles of Example 1 and Comparative Examples 1 to 5 manufactured was measured. The thermal conductivity was measured by a hot wire method (probe method) based on JIS R2616 (2001). For the measurement, “QTM-D3” manufactured by Kyoto Electronics Industry Co., Ltd. was used. FIG. 8 shows the measurement results of thermal conductivity.

  As shown in FIG. 8, the thermal conductivity of the urethane foam molded body of Example 1 was much higher than that of each urethane foam molded body of the comparative example. For example, the urethane foam molded article of Comparative Example 5 contains both carbon fibers and iron powder, like the urethane foam molded article of Example 1. Nevertheless, the thermal conductivity was almost the same as that of the urethane foam molded article of Comparative Example 2 containing only carbon fibers. The urethane foam molded article of Comparative Example 5 is foam molded without applying a magnetic field. For this reason, it is considered that the iron powder is not oriented and the desired skeleton is not constructed. In addition, the heat conductivity of the comparative example 2 urethane foam molding containing only carbon fiber was large compared with the urethane foam molding of the comparative examples 3 and 4 containing only iron powder. From the above results, it is confirmed that even if the high thermal conductive filler is a non-magnetic material, a urethane foam molded product with high thermal conductivity can be obtained by blending with magnetic particles and foam molding in a magnetic field. It was done.

<Measurement of sound absorption coefficient>
The sound absorption coefficient of the urethane foam moldings of Example 1 and Comparative Example 1 was measured. The sound absorption coefficient was measured in accordance with the normal incident sound absorption coefficient method of JIS A 1405. Here, the incident direction of the sound wave was set to be the same as the axial direction of the urethane foam molded body (vertical direction in FIG. 4). FIG. 9 shows the measurement result of the sound absorption coefficient. In FIG. 9, the urethane foam molded article of Example 1 is indicated by a thick line, and the urethane foam molded article of Comparative Example 1 is indicated by a thin line.

  As shown in FIG. 9, the urethane foam molded article of Example 1 exhibited substantially the same sound absorption characteristics as the urethane foam molded article of Comparative Example 1. Thus, the urethane foam molded article of the present invention has high thermal conductivity while maintaining predetermined sound absorption characteristics.

  The urethane foam molded article of the present invention can be used in a wide range of fields such as automobiles, electronic equipment, and architecture. For example, soundproof tires for reducing noise caused by road surface unevenness, engine covers and side covers arranged in the engine room of a vehicle to reduce engine noise, motors for office automation (OA) devices and home appliances It is suitable for a sound absorbing material for a house, a heat radiating sound absorbing material for an electronic device such as a personal computer, and a sound absorbing material for an inner and outer wall of a house.

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 9: Mixed raw material 90: Foamed urethane resin raw material 900: Foam stabilizer 91: Magnetic particles 92: High thermal conductive filler 93: Bubble 930: Foam film

Claims (7)

The skeletal resin partitioning the cell has a foamed body made of polyurethane foam extending in a streak shape from one end to the other end, and the skeleton resin has a magnetic material oriented in the direction from the one end to the other end. A method for producing a urethane foam molded article comprising body particles and a highly thermally conductive filler made of a non-magnetic material and connected to each other in the direction from the one end to the other end ,
A raw material mixing step of mixing a foamed urethane resin raw material, the magnetic particles, and the high thermal conductive filler into a mixed raw material;
A foaming step of injecting the mixed raw material into a cavity of a foaming mold and foaming in a magnetic field formed from one end of the cavity toward the other end and having a magnetic flux density difference within ± 10%;
A method for producing a urethane foam molded article comprising: The method for producing a urethane foam molded article according to claim 1, wherein the high thermal conductive filler is carbon fiber. The method for producing a urethane foam molded article according to claim 1 or 2, wherein the magnetic particles are iron powder. 4. The method for producing a urethane foam molded article according to claim 1, wherein a particle diameter of the magnetic particles is 100 μm or less. 5. The method for producing a urethane foam molded article according to any one of claims 1 to 4, wherein the high thermal conductivity filler has a thermal conductivity of 500 W / m · K or more. The foamed urethane resin material comprises a polyol material containing polyol and a polyisocyanate material containing polyisocyanate,
The magnetic particles and the high thermal conductive filler are previously blended and prepared in at least one of the polyol raw material and the polyisocyanate raw material,
The method for producing a urethane foam molded article according to any one of claims 1 to 5, wherein the polyol raw material and the polyisocyanate raw material are mixed by jetting and colliding with each other to form the mixed raw material. . The method for producing a urethane foam molded article according to claim 6 , wherein maximum lengths of the magnetic particles and the high thermal conductive filler are smaller than a diameter of an injection hole into which the polyol raw material and the polyisocyanate raw material are injected.