JP2009073160A - Urethane foam molded article and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a urethane foam molded article having new structure and a manufacturing method thereof. <P>SOLUTION: The urethane foam molded article includes a foamed main body which has cavities aligned so as to run from one end toward another end. The urethane foam molded article is manufactured by pouring a mixture material obtained by blending a foaming urethane resin raw material with a magnetic viscous fluid into a foaming mold and foaming the mixture material in a magnetic field running from one end of the foaming mold toward another end. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a urethane foam molded article and a method for producing the same.

  Urethane foam moldings are widely used in various fields such as daily necessities, automobiles, and architecture as cushion materials, sound absorbing materials, vibration absorbing materials, and the like (see, for example, Patent Documents 1 and 2). The characteristics of the urethane foam molded product vary depending on the size, shape, openability, etc. of small bubbles called cells. For this reason, the structure of the cell is important in the design of a urethane foam molded article.

For example, Patent Document 3 describes that the cell size can be adjusted by the blending amount of a polyisocyanate component and a polyol component as raw materials, the blending amount of a foaming agent and a foam stabilizer, and the like. Patent Document 4 introduces a technology to obtain a urethane foam molded product with a biased density by using a foamed urethane resin material blended with a magnetic material and foaming while attracting the magnetic material by applying a magnetic field from one direction. Has been.
JP-T-2002-511917 JP 2005-48023 A JP-A-11-230157 JP 2006-181777 A

  For example, when a urethane foam molded body is used for an impact absorbing member mounted on an automobile or the like, it absorbs impact energy by deforming itself due to buckling or the like due to impact while securing necessary rigidity. Is required. In addition, when urethane foam moldings are used for the upper support for supporting the suspension on the vehicle body, softness in the vertical direction of the vehicle is required from the viewpoint of ride comfort, and hardness in the horizontal direction is required from the viewpoint of handling stability. Is done. Thus, various properties are required for urethane foam moldings depending on the application.

  However, conventionally, the size and density of the cells can only be adjusted, and the cell structure itself cannot be controlled. Therefore, it has been difficult to obtain desired characteristics.

  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 new structure, and its manufacturing method.

  (1) The urethane foam molded article of the present invention has a foam main body having pores oriented so as to communicate from one end to the other end (corresponding to claim 1). That is, the foamed body is not a cell having regularity and directionality as in the prior art, but has oriented pores. Here, “oriented holes” refers to holes arranged in a predetermined direction with a certain regularity. “One end” and “the other end” do not necessarily have to face each other by 180 degrees. For example, the hole may be formed in a straight line between one end and the other end or may be formed in a curved line. Moreover, you may form radially from the center toward the outer periphery. Moreover, you may form in the shape which combined these shapes. In addition, the holes communicate from one end to the other end. For this reason, when one end or the other end of the foam main body is viewed in plan, an opening of a hole penetrating the foam main body is observed.

  The urethane foam molded article of the present invention having such a foam main body exhibits the characteristics in which the characteristics due to the above-described pore structure and the characteristics derived from the urethane foam material are combined. For example, the urethane foam molded article of the present invention has high rigidity in the orientation direction of the pores. This is considered due to the orientation of the holes. Further, when a load is applied in the orientation direction of the holes, it buckles at a certain load and exhibits energy attenuation. This is considered to be due to the addition of the characteristics due to the pore structure to the characteristics derived from the urethane foam material. Furthermore, it recovers when the applied load is removed. This is considered to be due to the characteristics derived from the urethane foam material.

  Further, the characteristics in the orientation direction of the holes are different from the characteristics in the direction crossing the orientation direction. That is, the urethane foam molded article of the present invention has anisotropy. Therefore, it is suitable for applications requiring anisotropy, for example, a rubber member for an upper support for a suspension of a vehicle, a bound stopper for absorbing an impact, and the like.

  (2) Moreover, the manufacturing method of the urethane foam molding of this invention mixes a foaming urethane resin raw material and a magnetorheological fluid, prepares a mixed material, and injects this mixed material into a foaming mold, And a foaming step of foaming in a magnetic field from one end to the other end of the foaming mold (corresponding to claim 9).

  In the method for producing a urethane foam molded article of the present invention, a mixed material obtained by mixing a foamed urethane resin raw material and a magnetorheological fluid is used. A magnetorheological fluid is a fluid in which fine particles having ferromagnetism are dispersed in a solvent at a high concentration. When a magnetic field is applied to the magnetorheological fluid, the dispersed magnetic particles are connected along the direction of the magnetic field to form a chain cluster. For this reason, the viscosity of the magnetorheological fluid increases rapidly. During foam molding in a magnetic field, the magnetorheological fluid thickens and is oriented in the direction of the magnetic field, that is, from one end of the foaming mold to the other.

  The reaction in the foaming process is considered as follows. FIG. 11 shows a model of a part of the reaction in the foaming process. As shown in FIG. 11A, in the foaming step, bubbles 92 are generated in the foamed urethane resin raw material 90. The surface of the bubble 92 film (foam film) 920 is stabilized by the foam stabilizer 900 contained in the foamed urethane resin raw material 90. A magnetorheological fluid 91 is mixed in the foamed urethane resin raw material 90. The magnetorheological fluid 91 is formed by dispersing magnetic particles 911 in a solvent 910. When the bubble 92 is generated, the magnetorheological fluid 91 enters the bubble film 920. That is, the solvent 910 serves as a carrier, and the magnetic particles 911 enter the foam film 920. On the other hand, the solvent 910 has a bubble breaking action. Therefore, as shown in FIG. 11B, the bubbles 92 are destroyed by the solvent 910 that has entered the bubble film 920. Here, when a magnetic field is applied (the magnetic field is in the vertical direction in the figure), the foam film 920 flows due to the orientation of the magnetic particles 911, and a skeleton of a urethane foam molded body is formed. As a result, pores oriented to communicate from one end to the other end are formed.

  Thus, according to the manufacturing method of the present invention, the urethane foam molded article of the present invention can be easily manufactured. Moreover, both the foamed urethane resin raw material and the magnetorheological fluid are liquid. Therefore, the mixed state of the two is good, and there is no problem of sedimentation and poor dispersibility of the powder particles that occur when using a magnetic powder. In addition, handling is easier and less burden is placed on the equipment than when a powdered magnetic material is used.

  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 foamed body having pores oriented so as to communicate from one end to the other end. The pores of the foam main body only need to communicate from one end to the other end, and the individual pores may communicate in the middle. Further, the shape, size, number per unit area, etc. of the pores (openings) exposed on the end face of the foam main body are not particularly limited. Since these can be adjusted depending on the raw material, the foaming method, conditions, and the like, they may be appropriately adjusted according to the application.

  Moreover, the urethane foam molded article of the present invention may have a skin layer that seals pores at least one of one end and the other end of the foam main body. The skin layer is usually formed by foaming urethane resin raw material coming into contact with the inner wall of the foaming mold and suppressing foaming when the foamed urethane resin raw material is foam-molded in a sealed foaming mold. In this case, the air holes communicating from one end of the foam main body to the other end are sealed by the skin layer. The urethane foam molded article of the present invention has a low flow resistance in the pore orientation direction. For this reason, the formed skin layer can vibrate relatively freely. Therefore, for example, when sound waves are incident from the side on which the skin layer is formed, it is possible to obtain a sound absorption effect due to membrane vibration of the skin layer. The thickness of the skin layer is not particularly limited, but may be, for example, 20 μm or less. The presence / absence, thickness, and the like of the skin layer may be adjusted by the amount of raw material filled in the foaming mold, foaming time, foaming temperature, and the like.

  Since the urethane foam molded article of the present invention has a foam main body having oriented pores, the characteristics differ between the orientation direction of the pores and the direction intersecting the orientation direction. That is, it has anisotropy. For example, it is desirable from the load-displacement curve in the urethane foam molded article of the present invention that the static spring constant in the orientation direction of the pores is at least twice the static spring constant in the direction substantially perpendicular to the orientation direction. It is more preferably 4 times or more, and even more preferably 10 times or more. The static spring constant in the present invention is a value calculated by dividing the load when a sample having a thickness of 20 mm is compressed 2 mm (10%) in the thickness direction by the displacement.

  The urethane foam molded article of the present invention can be produced by foam molding a mixed material containing a foamed urethane resin raw material and a magnetorheological fluid.

(1) Foamed urethane resin raw material 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, and 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.

(2) Magnetorheological fluid The magnetorheological fluid may be a fluid in which magnetic particles are dispersed in a solvent. For example, a magnetorheological fluid (Magneto-Rheological fluid; MR fluid) containing micron-sized magnetic particles. And a magnetic mixed fluid (MCF) in which micron-sized magnetic particles are mixed with a magnetic fluid (MF) containing nano-sized magnetic particles. 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.

In addition, from the viewpoint of improving foamability and producing a lighter urethane foam molded article, it is desirable that the content of an additive that inhibits foaming (for example, a stabilizer having a foam breaking effect) is small. . Moreover, it is desirable that the magnetic particles are dispersed substantially uniformly in the solvent. In order to satisfy such a requirement, for example, the magnetorheological fluid includes a solvent, magnetic particles dispersed in the solvent, and an anti-settling agent for suppressing sedimentation of the magnetic particles. Good. In addition, the additive (for example, coloring agent etc.) which does not inhibit foaming may be mix | blended with the magnetorheological fluid of this structure. According to this configuration, the foaming rate can be improved as compared with the case where the MR fluid or MCF is used, and for example, a lightweight urethane foam molded body having a density of 0.2 g / cm ³ or less is manufactured. can do. Furthermore, when the magnetorheological fluid is composed only of the solvent, the magnetic particles dispersed in the solvent, and the anti-settling agent for suppressing the settling of the magnetic particles, the weight of the urethane foam molded body is reduced. It is more suitable for cost reduction.

  Here, examples of the solvent in which the magnetic particles are dispersed include oil-based solvents such as kerosene, isoparaffin, and polyalphaolefin. Of these, poly-α-olefins are preferred because they are less likely to volatilize at room temperature or high temperature. The particle diameter of the magnetic particles is desirably 1 μm or more and 10 μm or less. Here, the maximum diameter of the magnetic particles is adopted as the particle diameter. When the particle diameter is less than 1 μm, the influence of the magnetic particles on the foam film when a magnetic field is applied is reduced. For this reason, it is difficult to control the foam film which becomes the skeleton of the cell. On the other hand, if the particle diameter exceeds 10 μm, the solvent and the magnetic particles are separated, and the magnetic particles are likely to settle. For this reason, there is a possibility that only the magnetic particles are oriented, and it becomes difficult to control the foam film. Further, as the anti-settling agent, smectite is suitable. Below, the suitable manufacturing method of the urethane foam molding of this invention is explained in full detail.

<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 foaming process. Hereinafter, each step will be described.

(1) Mixed material preparation process This process is a process for preparing a mixed material by mixing a foamed urethane resin raw material and a magnetorheological fluid. Since the urethane foam raw material and the magnetorheological fluid have been described above, the description thereof is omitted here. What is necessary is just to adjust suitably the compounding quantity of the magnetorheological fluid with respect to a foaming urethane resin raw material, considering the physical property of the urethane foam molding obtained so that a desired void | hole may be formed. For example, in order to ensure responsiveness to a magnetic field, it is desirable to blend the magnetorheological fluid with 10 parts by weight or more with respect to 100 parts by weight of the combined polyisocyanate component and polyol component. It is more preferable to blend 15 parts by weight or more. On the other hand, considering the physical properties of the urethane foam molded product and the influence on the reaction state, the blending amount of the magnetorheological fluid is 70 parts by weight or less with respect to 100 parts by weight of the combined polyisocyanate component and polyol component. It is desirable to do. More preferably, it is 40 parts by weight or less. The mixed material prepared by weighing and mixing the foamed urethane resin raw material and the magnetorheological fluid is immediately subjected to the next foaming step.

(2) Foaming step This step is a step in which the mixed material prepared in the mixed material preparation step is injected into a foaming mold and foamed in a magnetic field from one end to the other end of the foaming mold. When the magnetic field is formed linearly, it is desirable that the magnetic lines of force inside the foaming mold are formed so as to be substantially parallel from one end of the foaming mold to the other end. For example, magnets may be arranged in the vicinity of both surfaces of one end and the other end of the foam mold so as to sandwich the foam 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. In this case, since a magnetic field is formed inside the foaming mold by a magnet arranged 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 is easily controlled. However, a magnetic material may be appropriately used 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. Even if the 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 the effect of controlling the foaming flow by the magnetorheological fluid, and it is difficult to form the desired pores. In addition, it is not necessary to apply a magnetic field in all the time for performing foam molding.

  When the magnetic field is formed linearly, it is desirable that the magnetic flux density of the magnetic field acting on the foaming mold is substantially the same in the magnetic force direction from one end of the foaming mold to the other end and in the direction perpendicular to the magnetic force direction. For example, the difference in magnetic flux density inside the foaming mold is preferably within ± 10%. It is more preferable that it is within ± 5%, more preferably within ± 3%. By forming a uniform magnetic field inside the foaming mold, it is possible to form pores oriented in the same manner in the entire foam body.

  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 one end and the other end of the foam main body depending on the foam molding method. On the end face of the foamed main body on which the skin layer is formed, the pores are sealed by the skin layer. Note that 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.

(1) Manufacture of urethane foam molded body Two types of urethane foam molded bodies having skin layers at one or both ends of the foam main body were manufactured. First, a foamed urethane resin raw material was prepared as follows. Polyether polyol polyether polyol ("S-0248" manufactured by Sumika Bayer Urethane Co., Ltd., average molecular weight 6000, functional group number 3, OH value 28 mgKOH / g) 100 parts by weight, and crosslinking agent diethylene glycol (Mitsubishi Chemical Co., Ltd.) 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 Part by weight and 2 parts by weight of a carbon-based pigment (“FT-1576” manufactured by Dainichi Seika Kogyo Co., Ltd.) were mixed to prepare a premix polyol. 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, MR fluid ("E-600" manufactured by Sigma High Chemical Co., Ltd.) was mixed with the prepared foamed urethane resin material to obtain a mixed material. The MR fluid was compounded in an amount of 29.2 parts by weight with respect to 100 parts by weight of the polyol component polyether polyol and the polyisocyanate component MDI.

  Thereafter, the mixed material was poured into an aluminum foaming mold (see FIGS. 1 and 2 described later. The cavity was a cylindrical shape having a diameter of 100 mm × thickness of 20 mm) and sealed. At this time, two kinds of mixed materials were prepared by changing the injection amount of the mixed material. First, the mixed material was injected so that the foamed molded product did not reach the ceiling surface of the cavity at the end of foaming (open state). In the other, the mixed material was injected so that the foamed molded product reached the ceiling surface of the cavity at the end of foaming (closed state). In the former open state, a skin layer is formed only on the lower surface of the foam body. On the other hand, in the latter closed state, skin layers are formed on the upper and lower surfaces of the foam body.

  Subsequently, the foaming mold was installed in a magnetic field generator to perform foam molding. FIG. 1 is a perspective view of the magnetic field generator. FIG. 2 shows a partial cross-sectional view of the magnetic field generator. As shown in FIGS. 1 and 2, 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 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. 2) 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 two types of urethane foam moldings. The urethane foam molded body in which the skin layer is formed only on the lower surface of the foam main body, the foam molded body of Example 1, and the urethane foam molded body in which the skin layers are formed on the upper and lower surfaces of the foam main body are A foamed molded product was obtained. The photograph of the foaming molding of Example 1, 2 is shown in FIGS. FIG. 3 is a top view photograph of the foam molded article of Example 1. FIG. 4 is a photograph of the foam molded article of Example 1 taken from the upper front side. FIG. 5 is a photograph of the foamed molded product of Example 2 taken from the upper front side.

  As shown in FIG. 3, many openings of various shapes of pores are observed on the upper surface of the foam molded article of Example 1. In addition, since this photograph was taken by irradiating light from the lower surface side (the back side of the paper surface) of the foam molded body of Example 1, the opening of the hole is shown in white. As can be seen from the fact that light from the lower surface side reaches the upper surface through the holes, the holes communicate with each other in the vertical direction. However, the foam molded article of Example 1 has a skin layer on the lower surface side. For this reason, the void | hole is sealed by the skin layer in the lower surface side of the foaming molding of Example 1. FIG. On the other hand, as shown in FIG. 4, no skin layer is formed on the upper surface side of the foam molded article of Example 1. The upper surface of the foamed molded body of Example 1 has a labyrinth pattern in which partition walls that divide pores are connected like a maze.

  As shown in FIG. 5, the foamed molded product of Example 2 has a skin layer on the upper surface side. In addition, although it cannot be seen in this photograph, it has a similar skin layer on the lower surface side. For this reason, the air holes communicating in the vertical direction are sealed by the skin layer. Moreover, when the side part cross section of the foaming molding of Example 2 is seen, it turns out that the void | hole is connected and oriented in the up-down direction. In addition, a partition wall extending in the vertical direction is observed like a bark.

(2) Load test With respect to the foamed molded article of Example 2 manufactured, a load was applied from the upper side (the orientation direction of the holes) to the upper surface (area of diameter 100 mm≈78.5 cm ² ), and the displacement relative to the load was measured. did. For comparison, the foamed urethane resin raw material having the same composition as described above was increased by the amount of the MR fluid in the mixed material and foam-molded without applying a magnetic field to produce a urethane foam-molded body (hereinafter, This is referred to as the foamed molded article of Comparative Example 1). Further, the same mixed material as above was subjected to foam molding without applying a magnetic field to produce a urethane foam molded body (hereinafter referred to as the foam molded body of Comparative Example 2). Of course, not only the foam molded body of Comparative Example 1 containing no MR fluid but also the foam molded body of Comparative Example 2 foamed and molded without applying a magnetic field even when MR fluid was blended from one end to the other end. No vacancies oriented to communicate were formed. Similarly, the amount of displacement with respect to the load was also measured for the foamed molded products of Comparative Examples 1 and 2. Here, a load test of one cycle is performed until a predetermined load is applied and removed. In FIG. 6, the load-displacement curve about each foaming molding is shown.

  As shown in FIG. 6, it can be seen that the foam molded body of Example 2 has higher rigidity than the foam molded bodies of Comparative Examples 1 and 2. Further, in the foamed molded product of Example 2, the load temporarily decreased from around the displacement amount exceeding 2 mm, and energy attenuation was observed. Nevertheless, like the foamed molded products of Comparative Examples 1 and 2, the foamed molded product of Example 2 returned to a substantially original shape when the load was removed. Moreover, about the foaming molding of Example 2, the same load test was done again 1 hour after performing the load test of 1 cycle (2nd time). A load-displacement curve in the second load test is also shown in FIG. As shown in FIG. 6, the maximum load is slightly reduced, but it can be seen that the high rigidity, energy attenuation, and restoration are maintained.

  In addition, in order to evaluate the restoration property, the thickness of each foamed molded product was measured before and after a one-cycle load test. The results are shown in FIG. As shown in FIG. 7, in any foamed molded product, there was almost no change in thickness before and after the load test.

  Thus, according to the urethane foam molded article of the present invention, a characteristic in which the characteristic derived from the original urethane foam material and the characteristic obtained by the specific pore structure are combined is exhibited. For example, the urethane foam molded article of the present invention exhibits both energy attenuation and high rigidity. For this reason, the urethane foam molding of this invention is useful as an impact-absorbing material part etc.

(3) Anisotropy test A 20 mm square block-shaped sample was cut out from the foamed molded article of Example 2 above. Skin layers are formed on the upper and lower surfaces of the sample. A load was applied to the upper surface (20 mm × 20 mm = 4 cm ² ) of this sample (the compression direction was the same as the orientation direction of the holes), and the displacement with respect to the load was measured. Similarly, a load was applied to the right surface (20 mm × 20 mm = 4 cm ² ) of the sample (the compression direction was a direction substantially perpendicular to the orientation direction of the holes), and the displacement with respect to the load was measured. FIG. 8 shows a load-displacement curve in each measurement.

  For comparison, 20 mm square block samples were similarly cut out from the foamed molded products of Comparative Examples 1 and 2 above. A load was applied to the upper surface of these samples, and the amount of displacement with respect to the load was measured. Further, a load was applied to the right surface of the sample, and a displacement amount with respect to the load was measured. 9 and 10 show load-displacement curves in each measurement.

  As shown in FIG. 8, it can be seen that the sample of Example 2 has high rigidity in the vertical direction (the orientation direction of the holes). Further, when the static spring constant was compared when the displacement was 2 mm (compression ratio 10%) when compressed from the upper surface and when compressed from the right surface, the former was 18.83 times the latter. On the other hand, as shown in FIGS. 9 and 10, the samples of Comparative Examples 1 and 2 had almost no difference in rigidity due to the difference in the compression direction. About each sample, the static spring constant at the time of compressing from the upper surface and the static spring constant at the time of compressing from the right surface were compared like Example 2. As a result, the sample of Comparative Example 1 was 0.99 times, and the sample of Comparative Example 2 was 1.58 times. From the above, it can be seen that in the urethane foam molded article of the present invention, the characteristics in the orientation direction of the pores and the characteristics in the orientation direction and in the substantially vertical direction are greatly different.

  The urethane foam molded article of the present invention can be used for various applications in fields such as daily necessities and automobiles. Particularly, it is suitable for an impact absorbing member that makes use of energy attenuation, an upper support for a suspension that requires anisotropy, and the like.

It is a perspective view of the magnetic field generator used for manufacture of the urethane foam molding of an Example. It is a fragmentary sectional view of the magnetic field generator. 2 is a top view photograph of the foamed molded product of Example 1. FIG. It is the photograph which image | photographed the foaming molding of Example 1 from the front side upper direction. It is the photograph which image | photographed the foaming molding of Example 2 from the near upper side. It is a load-displacement curve about each foaming molding of Example 2 and Comparative Examples 1 and 2. It is a measurement result of the thickness before and after a load test about each foaming fabrication object of Example 2 and comparative examples 1 and 2. It is a load-displacement curve in the sample produced from the foaming molding of Example 2. FIG. It is a load-displacement curve in the sample produced from the foaming molding of the comparative example 1. It is a load-displacement curve in the sample produced from the foaming molding of the comparative example 2. It is a model figure which shows a part of reaction in the manufacture process of the urethane foam molded object of this invention.

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 90: Foamed urethane resin raw material 900: Foam stabilizer 91: Magnetorheological fluid 910: Solvent 911: Magnetic particles 92: Bubbles 920: Foam film

Claims (11)

  A urethane foam molded article having a foamed body having pores oriented so as to communicate from one end to the other end.   Furthermore, the urethane foam molding of Claim 1 which has a skin layer which seals the said void | hole in at least one of the said one end and the said other end of the said foaming main body.   The urethane foam molded article according to claim 1 or 2, wherein a static spring constant in the orientation direction of the pores is at least twice as large as a static spring constant in a direction substantially perpendicular to the orientation direction.   The urethane foam molded article according to claim 1 or 2, wherein a static spring constant in the orientation direction of the pores is 10 times or more of a static spring constant in a direction substantially perpendicular to the orientation direction.   The urethane foam molded article according to any one of claims 1 to 4, wherein a mixed material containing a foamed urethane resin raw material and a magnetorheological fluid is foam-molded. The magnetorheological fluid includes a solvent, magnetic particles dispersed in the solvent, and an anti-settling agent for suppressing settling of the magnetic particles,
The urethane foam molded article according to claim 5, wherein the density after foam molding is 0.2 g / cm ³ or less.   The urethane according to claim 5 or 6, wherein the magnetorheological fluid comprises only a solvent, magnetic particles dispersed in the solvent, and an anti-settling agent for suppressing settling of the magnetic particles. Foam molded body.   The urethane foam molded article according to claim 6 or 7, wherein a particle diameter of the magnetic particles is 1 µm or more and 10 µm or less. A mixed material preparation step of mixing a foamed urethane resin raw material and a magnetorheological fluid to prepare a mixed material;
A foaming step of pouring the mixed material into a foaming mold and foaming in a magnetic field from one end of the foaming mold to the other;
The manufacturing method of the urethane foam molding which has this.   The urethane foam molded article according to claim 9, wherein the magnetic flux density of the magnetic field acting on the foaming mold is substantially the same in a magnetic force direction from one end to the other end of the foaming mold and in a direction perpendicular to the magnetic force direction. Method. The foamed urethane resin raw material includes a polyisocyanate component and a polyol component,
The urethane foam according to claim 9 or 10, wherein a blending amount of the magnetorheological fluid is 10 parts by weight or more and 70 parts by weight or less with respect to 100 parts by weight of a combination of the polyisocyanate component and the polyol component. Manufacturing method of a molded object.