JP4659536B2 - Duct member and duct comprising the same - Google Patents

Description

  The present invention relates to a duct member and a duct formed by appropriately combining a plurality of the duct members.

  Usually, an automobile is provided with a large number of facilities in order to provide a comfortable and safe driving environment for passengers and the like, for example, air conditioning facilities. This air conditioning equipment basically includes a cooling mechanism including an evaporator and the like, a drive source such as a fan for sending out temperature-controlled air, an air conditioning duct, an outlet (outlet), and the like. Here, the air-conditioning duct is housed inside an automobile interior material, such as an instrument panel or a ceiling, and is configured to maintain a required outer shape so as to be a path through which temperature-controlled air flows without resistance.

In addition, in response to the reduction of automobile weight, which is part of the recent energy saving, air conditioning ducts are required to be further reduced in weight. In order to satisfy these requirements and to allow efficient distribution of temperature-controlled air, the air-conditioning duct can be made thin, and can be easily molded, and can be handled and shaped and retained after molding. For example, a blow molded article such as polyethylene (PE) resin having rigidity is preferably employed. In addition, as described in [Patent Document 1] below, a method is also disclosed in which a pipe that is flexible and easy to attach is employed as an air conditioning duct.
Japanese Patent Laid-Open No. 11-280959

  However, if the air conditioning duct is manufactured as a solid body such as the above-mentioned molded product of PE resin, the rigidity after molding can be secured, but there is a limit to its thinning, and it is difficult to achieve a certain weight reduction, On the other hand, when priority is given to weight reduction, the problem that the rigidity falls is inherent. Furthermore, when the air-conditioning duct is a solid body, internal noise generated from a driving source such as a fan, which is regarded as important in recent automobiles, cannot be reduced. In addition, in the case of the pipe disclosed in the above-mentioned invention “pipe for transporting gaseous fluid and manufacturing method thereof” described in [Patent Document 1], there is a problem that the structure is complicated and the manufacturing is complicated. .

  On the other hand, the invention “automobile air duct” described in [Patent Document 2], the invention “Air-conditioning duct” described in [Patent Document 3], and the invention “Gaseous Fluid” described in [Patent Document 4]. Various air-conditioning ducts are disclosed in “Airtight pipes to be transported and manufacturing methods thereof”. According to these inventions, the ease of processing is improved while maintaining the air permeability and rigidity of temperature-controlled air ([Patent Document 2]), or at least a part of the tube wall of the air conditioning duct is made of a porous material having air permeability. Air-conditioning noise radiated into the passenger compartment is reduced ([Patent Document 3]), and the first layer of porous material is reversibly mechanically deformable and flexible viscoelasticity. It can be inserted into a second layer made of a thin film of a liquid-tight material of a mold to form a pipe and attenuate sound ([Patent Document 4]).

  However, in the case of the invention described in [Patent Document 2], basically different sheets are combined to form a duct, so that the manufacturing process is complicated and the weight increases. In the case of the invention described in [Patent Document 3], since the air conditioning duct as the main body and the introduction part and the lead-out part for connecting the duct to other members are separately manufactured and integrated, the manufacturing process becomes complicated. In addition, the air conditioning duct cannot be said to have sufficient rigidity because of its material, and handling properties and the like are inferior. Also in the case of the invention described in [Patent Document 4], since it is necessary to integrate a plurality of layers, the production is not easy and the productivity is inferior. Further, like [Patent Document 3], there is a problem that it cannot be said that the material has sufficient rigidity because of its material.

The present invention has been proposed in order to suitably solve this problem in view of the problems associated with the prior art, and has a light weight and sufficient rigidity, such as air permeability and heat insulation required for a duct. It is an object of the present invention to provide a duct member capable of appropriately controlling various physical properties and a duct made of the duct member.
JP 2003-146051 A JP 2004-66908 A Japanese Patent Laid-Open No. 11-294648

In order to overcome the above problems and achieve the intended purpose, the invention according to claim 1
In a duct member comprising a main body part forming a wall of the duct and a flange part formed at a required position of the main body part,
A synthetic fiber composed of a core part made of a fiber of the first resin and a sheath part made of a second resin having a lower melting point than the first resin and covering the outer periphery of the core part is heated. Formed by molding into
The main body portion is formed with a plurality of fixing portions by melting and solidifying the sheath portions that are close to and in contact with each other while maintaining the fiber state of the synthetic fiber,
The apparent density of the main body is 0.1 g / cm ³ or more, and is set in a range less than the true density of the first resin or the second resin, which has a low true density,
The body part is molded by melting only the sheath part, and the flange part is completely melted by heating the core part and the sheath part with a higher compression ratio than the body part. The apparent density is set higher than that of the main body.

Therefore, according to the first aspect of the present invention, a duct member that exhibits remarkable effects such as excellent lightness, rigidity, heat insulation, anti-condensation and high sound absorption, that is, excellent low noise, can be easily manufactured. obtain. Since the flange portion having an apparent density set higher than that of the main body portion is provided, the rigidity of the duct member or the like can be greatly improved, and the structure can be easily attached to the automobile interior material or the like. Since the flange portion is formed by completely melting the core portion and the sheath portion, the flange portion has high rigidity and can further improve the rigidity of the main body portion. By setting the apparent density of the main body to a range of 0.1 g / cm ³ or more and less than the true density of the first resin or the second resin, which has a lower true density, a duct member made of a solid body, etc. As compared with the above, excellent heat insulation and dew condensation prevention and high sound absorption, that is, excellent low noise property can be exhibited. Furthermore, the duct member is molded by melting only the sheath portion of the main body portion, so that the air permeability and the like of the main body portion can be further improved.

The invention of claim 2 is the invention of claim 1 Symbol placement, ventilation as defined in JIS L 1096A of the main body portion is greater than 0, is a 30cm ³ / cm ² · S the range It is a summary. Therefore, according to the invention which concerns on Claim 2 , compared with the duct member etc. which consist of a solid body, the outstanding heat insulation, dew condensation prevention property, and high sound absorption property, ie, the outstanding low noise property, can be expressed.

A duct according to the invention described in claim 3 is formed by combining at least two or more duct members described in claim 1 or 2 . Therefore, according to the invention which concerns on Claim 3 , the duct which show | plays outstanding effect | action with outstanding heat insulation, dew condensation prevention property, and high sound absorption property, ie, the outstanding low noise property, can be manufactured easily.

  As described above, according to the duct member of the present invention and the duct made of the duct member, a duct member that is lightweight and has sufficient rigidity and a duct made of the duct member can be obtained.

Next, a duct member according to the present invention and a duct composed of the duct member will be described below with reference to the accompanying drawings by way of preferred embodiments. The inventor of the present application uses a synthetic fiber having a so-called core-sheath structure that employs different materials in the core part and the outer peripheral part (sheath part) as a material such as an air conditioning duct of an automobile. It has been found that a duct member (duct) having both rigidity capable of maintaining the shape can be manufactured. In the present invention, “melting” means that the second resin constituting the sheath exceeds the melting temperature and becomes liquid and is mixed with the sheath 12b without any boundary, and the second resin is softened. It refers to both the state and the state.

  In order to facilitate understanding of the duct member according to the embodiment, first, the synthetic fiber 12 having a core-sheath structure which is a material of the duct member will be described. As shown in FIG. 1, the synthetic fiber 12 has a core 12a made of the first resin on the inner side and a second resin having a lower melting point than the first resin so as to cover the outer side (outer periphery). A sheath portion 12b made of a material is provided (see FIG. 1A). Therefore, in the synthetic fiber sheet body 13 formed by assembling the synthetic fibers 12 into a sheet shape, the outer sheath portion 12b is melted by heating by applying predetermined heat, and then brought close to and in contact with each other by solidification accompanying cooling. The sheath portions 12b that are formed form a large number of fixing portions 14 (see FIG. 1B). That is, a strong skeleton as a whole is formed by bridging the plurality of core portions 12a by the fixing portions 14 formed in large numbers. This means that when the synthetic fiber sheet body 13 is heated and melted to obtain a molded body having a required shape, rigidity capable of retaining the shape is imparted. Furthermore, since the core portion 12a is less melted by the first resin as the material, the initial fiber state is maintained and the state in which many fine voids 16 are present is maintained.

  It is also possible to control the heating of the synthetic fiber 12 to form the fixing portion 14 so that only the sheath portion 12b is selectively melted and the core portion 12a is not melted at all. In this case, since the element in which the gap 16 is crushed becomes small, the initial fiber state of the synthetic fiber 12 is maintained substantially completely. Note that the fixation at the fixing portion 14 is not only a state in which the melted sheath portions 12b are welded to each other, as is apparent from the meaning of “melting” in the above ([0019]), but is also softened by heating. The state in which the sheath portions 12b are formed by being bonded by the softening is also included.

In this embodiment, crystalline polypropylene is used as the first resin, and polyethylene is used as the second resin. However, the present invention is not limited to this. Specifically, the second resin is a resin that melts at a temperature lower than that of the first resin and develops thermal welding (softening adhesion), and the first resin is thermally stable at the melting temperature of the second resin. Each resin is used. Any material can be adopted as long as the core portion 12a is configured to form the fixing portion 14 from the sheath portion 12b while maintaining its fiber state. In addition, about the material of the core part 12a, it is preferable from the point of higher rigidity etc. to show fixed plasticity with respect to the heat | fever applied at the time of formation of the adhering part 14. FIG .

  The two duct members 10 and 10 (the first duct member 10a and the second duct member 10b) according to the present embodiment are formed in the shape of an air conditioning duct that requires the above-described synthetic fiber sheet body 13 (synthetic fiber 12). It is formed (the manufacturing method will be described later [0032]), and as shown in FIG. 2, by joining both duct members 10 and 10 (first duct member 10a and second duct member 10b), FIG. The duct 11 shown in FIG. Here, the first duct member 10a and the second duct member 10b are joined and integrated with, for example, a hot melt adhesive to form the duct 11. The duct member 10 includes a main body 18 that forms the main part thereof, and a flange 20 that is formed at a required portion of the main body 18 and has an apparent density higher than that of the main body 18 (details will be described later [0030]). It consists of and.

  The duct member 10 (duct 11) employs the above-described synthetic fiber 12 (synthetic fiber sheet body 13) as its material. For this reason, as shown in FIG. 4, the surface state is such that a large number of synthetic fibers 12 are joined together by melting the sheath portion 12b covering the outer periphery while substantially maintaining the fiber state (core portion 12a). The fixed portion 14 is formed. That is, until the adhering portion 14 is formed, the synthetic fiber sheet body 13 is merely an aggregate of the synthetic fibers 12 as shown in FIG. 5 (see FIG. 5 (a)). Can be freely deformed (see FIG. 5B). On the other hand, after the fixing portion 14 is formed, the fixing portion 14 becomes a knot point of each synthetic fiber 12, and in order to limit its free movement, after being molded into a required shape under one end heating, That shape is retained (see FIG. 4).

  By using the synthetic fiber 12 having such characteristics as the material, the duct member 10 (duct 11) according to the present invention exhibits the following characteristics. That is, (1) Since the shape can be freely changed until the sheath portion 12b is melted and solidified, the duct member 10 (duct 11) having a complicated three-dimensional shape can be easily manufactured. After the sheath portion 12b is melted and solidified, a large number of fixing portions 14 are formed from the sheath portion 12b located on the surface of the synthetic fiber 12, so that (2) good moldability and sufficient rigidity as a molded body ( Good shape retention and handling properties as a product can be ensured. Further, since the gap 16 is retained and remains in the portion other than the fixing portion 14, (3) the apparent density is small and light, (4) the air permeability is ensured, and the high sound absorption property and the anti-condensation effect are obtained. I can expect. The (3) apparent density and (4) air permeability refer to the numerical values of the main body 18 in the duct member 10 (duct 11).

In particular, (3) apparent density (molding density of the main body 18) and (4) air permeability are the weight per unit area of the synthetic fiber 12 (synthetic fiber sheet body 13) before heating and melting, the molding compressibility, and the heating temperature. The numerical value can be easily controlled by adjusting the time. Specifically, (3) the apparent density is not less than 0.1 g / cm ³ and less than the true density of the first resin or the second resin constituting the synthetic fiber 12 which has a lower true density. The If it is this numerical range, it can be set as the molded object provided with (4) air permeability mentioned later and sufficient rigidity as the duct member 10 (duct 11). When this value is less than 0.1 g / cm ³ , sufficient rigidity as the duct member 10 (duct 11) cannot be secured. On the other hand, when the true density of the first resin or the second resin constituting the synthetic fiber 12 is reached, the synthetic fiber 12 (synthetic fiber sheet body 13) is almost completely melted. However, the property is substantially in a solid state, and it becomes impossible to obtain the characteristics achieved by reducing the weight and ensuring air permeability. In the first resin and the second resin in this example, the crystalline polypropylene, which is the material of the core 12a, has a lower true density, and its density is around 0.9 g / cm ^3. There is an upper limit.

(4) In the present invention, the air permeability of the main body portion 18 adopts that defined in JIS L 1096A (Fragile type method), and the numerical value exceeds 0 and is 30 cm ³ / cm ² · S or less. It is considered as a range. By being in this range, airflow related to the wall portion of the duct member 10 formed by the main body portion 18 such as the flowability of temperature-controlled air sufficient as an air conditioning duct, low noise property, high heat insulating property, and dew condensation prevention property. It can be combined with the effect related to sex. Therefore, when the numerical value is 0 cm ³ / cm ² · S, that is, when the property is solid, the above-described effects derived from the air permeability cannot be used. On the other hand, when exceeding 30 cm < ³ > / cm < ² > * S, the interruption | blocking property of the temperature control air which distribute | circulates the inside of the duct member 10 (duct 11) falls, and cannot fully fulfill | perform the function as a duct.

  Comparing this with a general nonwoven fabric, the entire nonwoven fabric is composed of a substance (resin) having the same melting point, and therefore, until a large number of fibers forming the nonwoven fabric are melted by heating. It is the same and can be easily formed into a free shape. However, once melted, the entire number of fibers forming the nonwoven fabric is melted. This also means that the fiber forming the nonwoven fabric develops fluidity, spreads two-dimensionally due to the fluidity, and exhibits a solid property. In this case, the effect of the duct member 10 (duct 11) according to the present invention is not obtained at all.

  On the other hand, if the heating temperature is low, the characteristics as the fiber assembly, that is, the air permeability, is ensured, but the shape of the formed body cannot be maintained because there are no or few fixed portions that retain the shape. Also, the degree of freedom of molding is low, and for example, a duct having a deeply carved part cannot be suitably manufactured.

  Further, the first duct member 10a and the second duct member 10b are formed with flange portions 20 and 20 as margin portions for bonding at the end portions thereof (see FIG. 2). Further, when the duct 11 is formed, flanges 20 and 20 are provided as attachment portions for easily performing the attachment at a portion where the duct 11 is attached to the in-vehicle air outlet (outlet) (see FIG. 1 and FIG. 1). (See FIG. 2).

  In the present invention, the flange portion 20 is formed by increasing the compression ratio of the predetermined portion corresponding to the synthetic fiber sheet body 13 by molding and melt-compressing. In this way, by intentionally forming the flange portion 20 having an apparent density higher than that of the main body portion 18 at the end portion of the duct member 10 and the like, the duct 11 can be easily manufactured and attached to the interior of the automobile. There is an effect. Furthermore, the rigidity of the duct member 10 (duct 11) as a whole can be further improved, and its shape retention and handling properties can be improved. Note that the synthetic fiber sheet body 13 can be easily formed by subjecting only the flange portion 20 to a temperature at which even the core portion 12a can be melted to melt and compress the synthetic fiber sheet body 13 almost completely. In this case, not only the sheath portion 12b but also the core portion 12a is in a state close to a molten solid body, and the rigidity of the entire duct member 10 (duct 11) can be further improved.

(Example of manufacturing method)
Below, an example of the manufacturing method of the duct 11 which concerns on a present Example is demonstrated. As shown in FIG. 6, the manufacturing method of the duct 11 is performed by using a cotton pattern or the like having the above-described synthetic fiber 12 in a predetermined shape, and heating the synthetic fiber sheet body 13 which is the obtained laminated sheet, The melting stage S1 in which the 12 sheath portions 12b are in a molten state and the synthetic fiber 12 in which the sheath portion 12b is in a molten state are molded while being compressed by a required mold 26 (see FIG. 7 (described later [0034])). It basically consists of a compression molding stage S2 and a final stage S3.

  The melting stage S <b> 1 is a stage in which the synthetic fiber sheet body 13 is given sufficient heat to melt the sheath 12 b. Since the synthetic fiber 12 in this embodiment has high heat insulation properties, the synthetic fiber 12 is heated from both sides in the thickness direction of the synthetic fiber sheet 13 for the purpose of suitable heating. The temperature to be added is the melting temperature of the sheath 12b, which is about 130 to 140 ° C. in the present embodiment.

  In the next compression molding step S2, the outer shape of the duct member 10 (here, the first duct member 10a) shown in FIG. This is a stage where press molding is performed by applying a required molding compression force using a molding die 26 having an inner contour shape that matches with the upper die 26a and the lower die 26b. First, the upper mold 26a and the lower mold 26b are separated from each other, and the synthetic fiber sheet body 13 composed of the synthetic fibers 12 in which the sheath portion 12b is in a molten state is disposed therebetween (see FIG. 7B). Then, the mold 26 is closed while the upper die 26a and the lower die 26b are gradually approached, and the synthetic fiber sheet body 13 is press-molded to form the first duct member 10a (FIGS. 7C and 7C). d)). Then, the molded first duct member 10 a is removed from the mold 26.

  Further, in the main compression molding step S2, the apparent density of the first duct member 10a is determined. That is, when the thickness of the synthetic fiber sheet body 13 before compression molding is T and the apparent density is D, if the thickness of the inner contour shape of the mold 26 (= thickness of the first duct member 10a) is t, compression molding is performed. The apparent density of the subsequent first duct member 10a can be calculated and controlled by D × (T / t). That is, the apparent density of the first duct member 10a can be set finely for each part by the design of the inner contour shape of the mold 26 and the thickness of the synthetic fiber sheet body 13. Needless to say, the air permeability can be controlled by setting the apparent density.

  The first duct member 10a having a desired thickness, apparent density, and air permeability can be obtained through the steps S1 and S2 so far. In the final stage S3 to be finally performed, the second duct member 10b is manufactured through a similar process by cutting unnecessary parts and performing a predetermined inspection on the molded first duct member 10a. This is the stage of obtaining the duct 11 which is a finished product.

  In this manufacturing method, the synthetic fibers 12 are preliminarily assembled in a laminated manner to form a sheet-like synthetic fiber sheet 13 and then heated and melted. However, the present invention is not limited to this. The duct member 10 may be obtained by simply heating and compressing a necessary amount of the synthetic fibers 12 in an aggregated state and directly heating and compressing them.

(Another example)
In the above-described embodiment, the two duct members 10 and 10 (the first duct member 10a and the second duct member 10b) are joined to obtain the finished duct 11, but the present invention is limited to this. It is not a thing. For example, in order to blow out air from an air outlet provided in the ceiling of an automobile, the duct member 10 is disposed on the back side of the ceiling member 30 by adhesion or the like with the opening side in close contact as shown in FIG. It is also possible.

(Experimental example)
Hereinafter, experimental examples of the duct member according to the present invention and a duct made of the duct member will be described. In addition, this experiment example is an example of the duct member which concerns on this invention, and a duct which consists of this, Comprising: The content is not limited.

(Experiment 1) Apparent Density and Breathability Synthetic fiber sheet made of synthetic fiber (trade name: NBF; manufactured by Daiwa Boseki Co., Ltd.) made of crystalline polypropylene for the core and polyethylene for the sheath ( 10 mm in thickness and an apparent density of 0.07 g / cm ³ ), which is heated to a surface temperature of 130 to 140 ° C., and is about 1 minute in the required mold shown in FIG. Compression is performed under the conditions, and the duct member according to Examples 1 to 4 is manufactured by a mold having a cavity (compression ratio) described in Table 1 below, and the actual thickness (mm) after the molding, Apparent density (g / cm ³ ) and air permeability (cm ³ / cm ² · S) were measured. Measurement methods and conditions are as follows.

(Measurement method and conditions)
-Thickness: Considering the variation depending on the site, measurement was made at a total of 4 points, and the average value was calculated.
-Apparent density: A part of the main body of the duct was cut out and calculated from the volume and weight calculated from the dimensions. Similar to the thickness, the average value was calculated from a total of 5 points in consideration of variation depending on the part.
-Breathability: Measured according to the method specified in JIS L 1096A (Fragile type method). The measurement was performed twice and the average value was calculated. In the measurement, a sample piece of the duct member according to Examples 1 to 4 previously cut to a required size is sandwiched and fixed between two rings having an inner hole of φ50, and the upper side is fixed here. This is done by circulating air under the condition of 125 Pa.

(Result of Experiment 1)
The results of Experiment 1 are also listed in Table 1 below. From Table 1, it was confirmed that any duct member has physical properties that can be suitably used. Moreover, a certain level of air permeability was ensured.

(Experiment 2) Sound Absorption, Pressure Loss, Weight, and Thermal Conductivity as a Duct Next, the shapes shown in FIG. 3 according to Example 5 and Comparative Examples 1 and 2 under the conditions described in Table 2 below. The sound absorption (db), weight (g) and thermal conductivity (W / m · K) were measured, and the difference based on Comparative Example 2 was calculated. In addition, the duct according to Example 5 is a duct member (second duct member) which is paired with the duct member (first duct member 10a) according to Example 2 (thickness 2 mm) manufactured in Experiment 1 and is paired with this. 10b) was bonded with a hot melt adhesive. The measurement method / conditions and the contents of Comparative Example 1 or 2 are as follows.

(Measurement method and conditions)
Sound absorption: Using the apparatus shown in FIG. 9, the duct according to each example or comparative example is installed, the sound pressure of each frequency is measured by a sound collecting device (microphone), and OA. The (overall) value was calculated. The reason why the absorbent material is arranged on the upper part of the duct as the test object is to selectively measure and evaluate only the sound generated from the vicinity of the duct outlet.
-Thermal conductivity: Based on JIS A 1412-2, the duct which concerns on each Example and a comparative example was processed into the test piece of required shape, and was measured.
Comparative Example 1: A duct made of general-purpose HDPE (high density polyethylene) into a duct shape shown in FIG.
Comparative Example 2: Internal sound-absorbing urethane (thickness: 5 mm, foaming density: 0.025 g / cm ³ ) normally used at the required position of the duct of Comparative Example 1 (A region (near the outlet) in FIG. ³ ) Placed duct.

(Result of Experiment 2)
The results of Experiment 2 are described together with Table 2 below, and the sound pressure at each frequency is shown in FIG. From Table 2 and FIG. 10, it was confirmed that the duct (duct member) according to the present invention is greatly improved in noise performance, weight, low thermal conductivity and the like as compared with the conventional ducts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a synthetic fiber constituting a duct member (duct) according to a preferred embodiment of the present invention, with (a) a state before heating and (b) a state after heating, each partially cut away. . It is a perspective view which shows two duct members which concern on an Example. It is a perspective view which shows the duct comprised from the two duct members of FIG. It is the schematic which shows the state after the heating of a synthetic fiber sheet body. It is the schematic which shows the state before the heating of a synthetic fiber sheet body. It is process drawing which shows an example of the manufacturing method of the duct which concerns on an Example. It is a state figure which shows the compression molding stage using the shaping | molding die used with the manufacturing method of FIG. It is the schematic of the duct which concerns on another Example. It is the schematic of the apparatus which evaluates the sound absorptivity of the experiment 2. FIG. It is a graph which shows the sound absorptivity result of Experiment 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Duct member, 12 Synthetic fiber, 12a Core part, 12b Sheath part, 14 Adhering part 18 Main body part, 20 Flange part, 32 Duct member

Claims (3)

In a duct member comprising a main body portion (18) forming a wall of a duct, and a flange portion (20) formed at a required position of the main body portion (18),
From a core part (12a) made of a fiber of the first resin and a sheath part (12b) made of a second resin having a melting point lower than that of the first resin and covering the outer periphery of the core part (12a) The synthetic fiber (12) that is composed is formed by molding under heating,
The main body portion (18) maintains a fiber state of the synthetic fiber (12) and melts and solidifies the sheath portions (12b, 12b) that are in close proximity to and in contact with each other to obtain a large number of fixing portions. (14) is formed,
The apparent density of the main body (18) is 0.1 g / cm ³ or more, and is set to a range less than the true density of the first resin or the second resin, which has a lower true density,
The body portion (18) is formed by melting only the sheath portion (12b), and the flange portion (20) has a higher compressibility than the body portion (18). A duct member characterized in that (12a) and the sheath (12b) are completely melted by heating so that the apparent density is set higher than that of the main body (18). The duct member according to claim 1, wherein the air permeability defined in JIS L 1096A of the main body (18) is in a range of more than 0 and 30 cm ³ / cm ² · S or less. It is formed by combining at least two or more duct members (10) according to claim 1 or 2.
A duct characterized by that.

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