JP2005193726A - Foaming duct - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To structure a foaming duct made by making resin foam by blow molding and molding the resin to a required shape, by foaming resin with a high expansion ratio. <P>SOLUTION: The foaming duct 1 is made by making the resin foam by blow molding and molding the resin to the required shape. The foaming duct 1 is structured by the foaming resin with the high expansion ratio. The foaming resin is polyolefin that is 2 to 5 in the expansion ratio, and 5 to 10gfMFR 1 to 5 in MT at 230°C. A core material for urging foaming is combined to the polyolefin resin by 2.5 to 7%, and the polyolefin resin is made to foam so as to have foaming bubbles with an average particle diameter of 100 to 300 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a foam duct mainly used as an air conditioning duct of an automobile, and relates to a foam duct formed by foaming a resin by blow molding and molding the resin into a required shape.

The air conditioning duct of an automobile is required to have high heat insulating properties and to prevent condensation on the surface of the duct. Conventionally, in order to satisfy this requirement, Japanese Patent Laid-Open No. 11-99579 has proposed that the outer surface of a duct is wound with a heat insulating material, and Japanese Patent Laid-Open No. 10-181334 discloses an organic decomposable material for a blow molded resin. JP-A-63-236620 and JP-A-2003-39536 propose a foamed duct formed by blending a chemical foaming agent and blow-molding a multilayer parison having a skin layer on the foamed layer. Proposed foam ducts.
JP 11-99579 A JP-A-10-181334 JP-A 63-236620 JP 2003-39536 A Special table 2001-527106

  The duct described in the above-mentioned Japanese Patent Application Laid-Open No. 11-99579 has a heat insulating effect. However, the manufacturing process is increased in order to integrate the heat insulating material with the duct, and the heat insulating material is formed on the curved duct surface. There was a problem that it was difficult to stick. Further, as described in the above-mentioned JP-A-10-181334, if a chemical foaming agent is blended into a resin and blow-molded, the duct line itself foams to obtain a duct having heat insulation properties. However, conventional foam ducts that are blow-molded with a degradable chemical foaming agent have many manufacturing problems in practice and have not yet been widely used as automotive air-conditioning ducts. The reason will be described next.

  When an inorganic agent such as ammonium bicarbonate or sodium bicarbonate, or an organic degradable chemical foaming agent such as dinitosopentamethylenetetraamine or asodicarbonamide is added to a polyolefin resin such as polypropylene or polyethylene, the cell expands as the temperature rises. There is a problem that the expansion of the parison decreases as the cell expands, and the blow moldability decreases. Further, the expansion of the cell has a problem that the cell tears on the inner surface of the parison that does not contact the cavity of the mold, and the required expansion ratio cannot be obtained. In particular, in a duct having connection ports at both ends of a pipe and the pipe through which air passes is bent in a complicated three-dimensional shape, the deterioration of blow moldability becomes a serious problem. For these reasons, foam blow molded ducts have many problems in commercialization.

  By the way, as described in the above-mentioned JP-A-63-236620 or JP-A-2003-39536, by providing a skin layer on the foam layer, it is possible to prevent destruction of foamed bubbles during blow molding. Even if it is possible, the foaming rate of the foamed layer is suppressed from having the skin layer, and there is a problem that a foaming duct having a high foaming rate cannot be obtained. There is also a description using volatility as a foaming agent. In the present invention, it is not volatile. This is different from the one using volatility, in which gaseous gas (carbon dioxide gas, nitrogen gas) is pressurized at normal temperature, put into the molten resin in a supercritical state, and foamed at normal pressure. Volatile blowing agents have the disadvantage of being flammable.

  On the other hand, as a technique for obtaining a foamed resin product without adding a foaming agent to the resin, a method of blow molding by blowing a gas such as nitrogen gas into the resin has been proposed (see Japanese Patent Application Publication No. 2001-527106). However, the above technique relates to a technique for producing a food container such as a milk bottle having a microporous foam cell of less than 60 μm, and an example of application to an air conditioning duct for automobiles as in the present invention is not disclosed.

  Accordingly, an object of the present invention is to provide a foam duct that can foam a resin by blow molding and can be molded into a required shape in order to cope with such a state of the art.

  In order to achieve the above object, a foam duct according to claim 1 of the present invention is provided in an air conditioner for an automobile, and includes a connection port portion that fits other members at both ends, and is provided between the connection port portions. Has a duct body in which a pipe passage through which air passes is bent into a three-dimensional shape, and the above-mentioned connection port and duct body have a foamed average particle diameter obtained by blow molding a single-layer parison foamed by a physical foaming method. It is comprised by the foam cell of 100-300 micrometers.

  The foam duct according to claim 2 of the present invention is the foamed resin according to claim 1, wherein the foamed resin is a polyolefin resin, the foaming ratio is 2 to 5 times, and the MT at 230 ° C. is 5 to 10 gfMFR1. It is characterized by being 5.

  Furthermore, the foam duct according to claim 3 of the present invention is the composition of claim 2, wherein the polyolefin resin is blended with 2.5 to 7% of a core material for promoting foaming, and the average particle diameter of the foamed cells is Is foamed so as to be 100 to 300 μm, and burrs are attached to the entire outer periphery.

  According to this invention, even if it is a foaming duct which foams resin by blow molding and shape | molds in a required shape, it can be comprised with the foaming resin of a high expansion ratio.

  FIG. 1 is a perspective view of a foam duct according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a blow molding aspect thereof, FIG. 3 is a cross-sectional view showing a state of clamping from the state of FIG. It is AA sectional drawing of FIG.

  In FIG. 1, reference numeral 1 denotes a foam duct, which illustrates an automobile air conditioning duct. 2 is a duct part, 3 is an inlet of a connection port, 4 is an outlet of a connection port, and 5 is a burr part. The foam duct 1 is formed by foaming a resin by blow molding and molding it into a required shape, and is made of a foam resin having a high expansion ratio. The foamed resin constituting the foamed duct 1 is a polyolefin resin, the foaming ratio is 2 to 5 times, and MT at 230 ° C. is 5 to 10 gfMFR1 to 5. A polyolefin resin is blended with 2.5 to 7% of a core material for promoting foaming, and foamed so that the average particle diameter of bubbles foamed during blow molding is 100 to 300 μm. The average particle diameter was determined by cutting the molded product and using the elliptical cross section of the bubble portion as the major axis of the average size ellipse. The core material is fine particles of talc, silica, mica, calcium carbonate, calcium silicate, barium sulfate, etc., and has the effect of attaching nitrogen gas blown into the molten resin during blow molding to generate small bubbles around it. .

  The foam duct 1 shown in FIG. 1 is blow-molded in the manner shown in FIGS. That is, 6 and 6 are a pair of split molds, 7 is an extrusion head, 8 is a parison, and the parison 8 extruded from the extrusion head 7 contains a core material and is blown with nitrogen gas. 9 is a burr | flash and is a part used as the burr | flash part 5 shown in FIG.

  2 and 3, the parison 8 is disposed between a pair of split molds 6 and 6, and the mold is clamped and blow-molded as shown in FIG. 3, but is blended into the parison 8 during blow molding. Since the nitrogen gas adhering to the core material is expanded to generate small bubbles, the molded body becomes a highly foamed body with small bubbles. FIG. 3 shows a blow nozzle for blow. For this reason, even if it is the foam duct 1 of a complicated shape as shown in FIG. 1, it can be blow-molded without causing destruction of bubbles.

  FIG. 5 is a front view, FIG. 6 is a side view, and FIG. 7 is a top view of the duct. As shown in FIGS. 5, 6, and 7, the duct body is subjected to three-dimensional bending and complicated bending. Moreover, since the both ends connection port of this duct has a fitting latching | locking part, it has a more complicated shape than the conventional duct. This shape also allowed blow molding. The details of the fitting locking portion are shown in FIG. The fitting locking portion of the duct is on the female side. Even such a fitting and locking portion can be molded without causing collapse of bubbles or becoming thinner than others.

  In the present invention, physical foaming means that a fine cell is grown at the time when the pressure and the critical temperature at which gas and liquid can coexist are exceeded (supercritical state) and the pressure reaches the atmospheric pressure. It is foamed and blow molded. In addition, the addition of the core material is effective as a means for quickly shifting the state that becomes thermodynamically unstable due to the pressure drop to the generation of bubble nuclei. In the present invention, since it is not necessary to use a conventional chemical foaming agent, a reduction in foaming ratio due to foaming or crushing of cells during blow molding is suppressed, and an automobile air conditioning duct having excellent dew condensation prevention properties is provided. be able to.

  The foam duct according to the present invention is not limited to an air conditioning duct of an automobile, but is excellent in versatility as a duct for various air conditioning.

It is a perspective view of the foaming duct which concerns on one embodiment of this invention. It is sectional drawing which shows the blow molding aspect. It is sectional drawing which shows the state clamped from the state of FIG. It is AA sectional drawing of FIG. It is a front view of a duct. It is a side view similarly. It is a top view similarly. It is a partially broken side view which shows the detail of a fitting latching part similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Foam duct 2 Duct part 3 Inlet 4 Outlet 5 Burr part 6,6 A pair of split mold 7 Extrusion head 8 Parison 9 Burr

Claims (3)

  In an air conditioner for an automobile, it has a connection port portion that fits other members at both ends, and a duct body in which a pipe passage through which air passes is bent in a three-dimensional shape between the connection port portions. The foamed duct is characterized in that the connection port and the duct body are made of foamed cells having a foamed average particle diameter of 100 to 300 μm by blow molding a single layer parison foamed by a physical foaming method.   2. The foamed duct according to claim 1, wherein the foamed resin is a polyolefin-based resin, the foaming ratio is 2 to 5 times, and MT at 230 ° C. is 5 to 10 gfMFR 1 to 5.   Mixing 2.5 to 7% of the core material for promoting foaming into polyolefin resin, foaming so that the average particle diameter of the foamed bubbles is 100 to 300 μm, and burring the entire outer periphery. The foamed duct according to claim 2, wherein

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