Abstract:
This thermal insulating sealing material can prevent breakage due to freezing. Formed from a water repellent urethane foam by mold forming. The impregnation of water during a car wash or rainy weather is prevented.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a thermal insulating sealing material provided and arranged around a radiator and that elastically contacts the bottom part of a cab to inhibit heat from an engine from flowing around to the front of the radiator.  
         [0003]     2. Description of the Related Art  
         [0004]     In an industrial vehicle, such as a truck, the engine room is confined and there is little available space because the cab is arranged on top of the engine. Consequently, as shown in  FIG. 2 , a structure is employed wherein a radiator  101  is arranged in front of an engine  100 , and while outside air is drawn in by a cooling fan  102  provided on the front surface side of the engine  100  rearward of the radiator  101 , heat is exchanged with the radiator  101 , after which the air passes through the periphery of the engine  100  and is then exhausted outside the vehicle from an outlet  104  provided in a lower cover  103  of the engine room.  
         [0005]     Incidentally, there is a problem in that the air that was heated by passing through the radiator and then further heated by the heat of the engine travels frontward along the bottom part of a cab  200  or the sidewalls of the engine room, causing a drop in the heat exchange function of the radiator  101 . Particularly in recent years, the adoption of fuel injection type engines has led to a trend in which engines have higher output with the engine itself running at increasingly higher temperatures, making it necessary to increase the cooling efficiency of the engine and the heat exchange function of the radiator  101 .  
         [0006]     Accordingly, as disclosed in, for example, Japanese Unexamined Utility Model Publication No. 05-065762 or Japanese Unexamined Patent Publication (KOKAI) No. 2000-204590, a partitioning member  300  made of a flame retardant resin foam is disposed around the radiator  101  so that the hot air present behind the radiator  101  does not flow around to the front of the radiator  101 . This partitioning member  300  is formed in a frame shape corresponding to the external shape of the radiator  101 , its upper surface elastically contacts a floor undersurface of the cab  200 , and both side surfaces elastically contact the sidewalls, and the like, of the engine room, thereby exhibiting sealing properties and preventing the flow of hot air present behind the radiator  101  around to the front of the radiator  101 .  
         [0007]     This partitioning member  300  is generally formed in a prescribed frame shape from urethane resin foam, and is used by bonding it to the radiator  101  with two-sided tape and the like, or by coupling it with bolts and the like. Urethane foam is ideal as a thermal insulating sealing material around the radiator  101  because it has low thermal conductivity, it is lightweight, and moreover it has excellent tracking characteristics due to its elasticity.  
         [0008]     Incidentally, in the case of a vehicle used in a cold region, if water that has impregnated the partitioning member during a car wash or rainy weather, then it may freeze to the opposite member at the elastic contact portion. Further, there is a problem in that, if the cab  200  is shaken, such as during inspection of the engine room, and the partitioning member  300  breaks at the frozen portion, then the sealing properties will decrease dramatically, leaving no choice but to replace the partitioning member  300 .  
         [0009]     Furthermore, although Japanese Unexamined Patent Publication (KOKAI) No. 2000-220467 recites a sound insulating material made of a low hydrophilic urethane foam, it does not recite or suggest its application as a thermal insulating sealing material around a radiator.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention takes the abovementioned circumstances into consideration, and has an object to prevent breakage due to freezing.  
         [0011]     A thermal insulating sealing material around a radiator of the present invention that solves the abovementioned problems is a thermal insulating sealing material provided and arranged around a radiator and that inhibits the flow of heat from an engine around to the front of the radiator by elastically contacting the bottom part of a cab, wherein the thermal insulating sealing material comprises a water repellent urethane foam.  
         [0012]     It is particularly preferable that the water repellent urethane foam contains a fluoro surfactant. In addition, it is preferably formed by mold forming.  
         [0013]     The thermal insulating sealing material of the present invention prevents the impregnation of water during a car wash or rainy weather because it is formed from a water repellent urethane foam. Accordingly, breakage due to freezing in cold regions is prevented, enabling it to be used for a long time. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a perspective view that depicts the state wherein the thermal insulating sealing material of the first embodiment according to the present invention is attached to a radiator.  
         [0015]      FIG. 2  is a schematic cross sectional view that depicts the configuration of an engine room having the thermal insulating sealing material. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     The thermal insulating sealing material of the present invention comprises a water repellent urethane foam. For the water repellent urethane foam, one in which a water repellent agent is bonded to a typical urethane foam, one in which a water repellent agent is included in the skeleton of the urethane foam, one in which the molecular skeleton of the urethane foam has a water repellent group, or the like, can be used.  
         [0017]     There are fluorine based and silicone based water repellent agents, which can be adhered to a urethane foam by a method that coats by spraying and the like. However, with this method, unevenness in the coating tends to arise because it is difficult to make visual confirmation, even if there are uncovered portions, and this deficiency tends to occur in cases where the urethane foam has a complex shape. In addition, there is a risk of freezing if exposed to a large quantity of water causing the water repellence to become insufficient. In addition, although it is possible to adhere a water repellent solution using a method such as impregnating and then drying the urethane foam, there is a problem in that the process is complicated.  
         [0018]     Therefore, it is preferable to use a urethane foam that includes a water repellent agent in the skeleton of the foam. This type of urethane foam can be manufactured by mixing in advance a water repellent agent in the resin foam raw ingredients, and foam forming in the presence of the water repellent agent. If manufacturing with this method, it is preferable to use a fluoro surfactant as the water repellent agent.  
         [0019]     For example, with respect to 100 parts by weight of the total amount of a polyol component and a polyisocyanate component, the fluoro surfactant is mixed at a proportion of 0.1-5 parts by weight, and foamed. For the fluoro surfactant, it is preferable to use one having an organic group with a fluoroaliphatic group having a carbon number of 3-20, particularly 6-12, and having an affinity for polyurethane resin. The compatibility with the polyurethane resin thereby increases. Within these, one having a perfluoro alkyl group is preferable.  
         [0020]     If a resin having a water repellent substituent, such as the fluorine group, is used in at least one of the polyol component and the polyisocyanate component, then a urethane foam having a water repellent group inside the molecular skeleton can be manufactured. If such a urethane foam is used, the water repellent agent will not be desorbed, and high water repellence can therefore be maintained over a long time period.  
         [0021]     Although it is possible to make the thermal insulating sealing material around the radiator in the present invention a prescribed shape by methods such as cutting the urethane foam, it is preferable to use, as is, urethane foam of a prescribed shape formed by mold forming. Because urethane foam formed by mold forming has an integral skin layer on the surface, the impregnation of water internally can be further suppressed, and freezing can be further prevented. In addition, if forming by mold forming, even complex seal shapes can be accommodated inexpensively. In particular, if using a urethane foam that includes a water repellent agent in the skeleton of the foam and that has an integral skin layer, then the water repellence can be particularly increased.  
         [0022]     The thermal insulating sealing material around the radiator of the present invention has a shape that exhibits sealing properties by wrapping around the radiator, elastically contacting the floor undersurface of the cab, and by both sides elastically contacting the sidewalls and the like of the engine room. The means of fixing to the radiator is not particularly limited to two-sided tape, bolts, claw engagement, and the like.  
       Embodiments  
       [0023]     The following concretely explains the present invention by embodiments and a comparative example.  
       First Embodiment  
       [0024]      FIG. 1  depicts a perspective view of a radiator provided with the thermal insulating sealing material of the present embodiment. A thermal insulating sealing material  1  is formed substantially U-shaped, and is bonded to a radiator  2  by a bolt so that it contacts the upper surface and both lateral surfaces of the radiator  2 . A steel plate (not shown) for fixing the bolts is integrally formed in the thermal insulating sealing material. The same as  FIG. 2 , the upper surface of the thermal insulating sealing material  1  elastically contacts the floor undersurface of the cab, and both lateral surfaces elastically contact the inner surface of the sidewalls of the engine room, thereby preventing the hot air of the engine room from flowing around to the front of the radiator  2 , and preventing a drop in the cooling efficiency of the radiator  2 .  
         [0025]     The thermal insulating sealing material  1  comprises a urethane foam provided with water repellence, and its entirety is integrally manufactured by mold forming. The following explains the method of manufacturing the thermal insulating sealing material  1 , and substitutes for a detailed explanation of the composition.  
         [0026]     The polyol component was prepared by mixing, with respect to 100 parts by weight of polyol (“Sumifine 3063” polyether polyol made by Sumika Bayer Urethane Co., Ltd., OH value=28, functional group=3), 0.15 parts by weight of a fluoro surfactant (“Megafac EXP.TF1068SF” made by Dainippon Ink and Chemicals, Inc., 60% solid content), 2.5 parts by weight of water, 1.3 parts by weight of an amine catalyst, and 0.5 parts by weight of a foaming agent.  
         [0027]     Meanwhile, denatured MDI (NCO=30-31%) was used as an isocyanate component and mixed with the abovementioned polyol component at a mixing ratio of NCO/OH=0.95, injected into a mold having a cavity the shape of the thermal insulating sealing material  1 , and foamed at 40°-70° C. for 10-30 minutes. The thermal insulating sealing material  1  obtained had an integral skin layer over its entire surface.  
         [0028]     Furthermore, simultaneous with forming the thermal insulating sealing material  1 , a test piece having dimensions of 100×100×50 mm was mold formed using the same raw ingredients, and submitted for testing, discussed later. An integral skin layer was formed across the entire surface of this test piece.  
       Second Embodiment  
       [0029]     The same as in the first embodiment, a test piece having dimensions of 100×100×50 mm was made by forming the urethane foam with a somewhat larger mold, and then peeling off the integral skin layer. In other words, the test piece of the present embodiment is the same as the one in the first embodiment except it does not have an integral skin layer.  
       COMPARATIVE EXAMPLE 1  
       [0030]     The test piece of the comparative example 1 was manufactured the same as in the first embodiment using a polyol component the same as in the first embodiment except that it does not include the fluoro surfactant. An integral skin layer was formed across the entire surface of this test piece.  
       Third Embodiment  
       [0031]     The entire surface of the test piece of the comparative example 1 was sprayed with a silicone based water repellent agent (“Cosmo Silicon Spray” made by Tsuchiya Co., Ltd.) in an amount of 10 g/m 2  to make the test piece of the present embodiment.  
       Testing and Evaluation  
       [0032]     The test pieces of the embodiments and the comparative example were mounted horizontally, and a water absorption test was performed by dumping from above at a height of 50 cm 1 L of water for approximately 20 s. This water absorption test was performed twice, and Table 1 lists the measurement results for the amount of water absorption based on the difference between the weight before water absorption and the weight after the first and second water absorptions. In addition, the percentage of water absorption was calculated after the second water absorption test, and that result is shown in Table 1. Furthermore, this test was respectively performed for different test pieces A, B.  
                                                                                           TABLE 1                                       Amount of               Water           Absorption   Water           (g)   Absorption                Skin       Initial Weight   First   Second   Percentage           Layer       (g)   Time   Time   (%)                        First   Urethane   Yes   A   50.4   12.4   15.8   31.3       Embodiment   containing       B   51.5   11.1   13.6   26.4           a water           repellent           agent       Second   Urethane   No   A   50.7   18.2   23.4   46.2       Embodiment   containing       B   51.2   19.5   24.4   47.7           a water           repellent           agent       Third   Coated with   Yes   A   50.8   16.2   21.6   42.6       Embodiment   a water       B   50.7   15.8   21.6   42.7           repellent           agent       Comparative   Urethane   Yes   A   51.2   16.8   24.6   48.0       Example 1   without a       B   53.5   17.0   27.6   51.6           water           repellent           agent                  
 
         [0033]     It can be seen in Table 1 that the water absorption percentage for the test piece of each embodiment is lower compared with the comparative example 1, thereby demonstrating water repellence. In addition, it is clear from a mutual comparison of the embodiments that using a urethane foam having a water repellent agent in the skeleton and moreover the test piece of the first embodiment having an integral skin layer have particularly excellent water repellence, and are ideally suited as the thermal insulating sealing material around the radiator. The second embodiment also demonstrates an advantageous effect, but falls short of the first embodiment. Further, the water repellence decreases greatly in the second embodiment, which does not have an integral skin layer, even with a urethane foam having a water repellent agent in the skeleton, and it is therefore understood that it is preferable to have an integral skin layer, i.e., to manufacture by mold forming.