JP7277740B2 - Duct and its manufacturing method - Google Patents

Description

The present invention relates to a duct and its manufacturing method.

Ducts are provided in dashboards and ceilings of automobiles to ventilate air from air conditioners. As such a duct, a foam duct made of a foam molding is sometimes used in consideration of heat insulation and quietness (Patent Document 1). The foam duct is formed by foam blow molding or the like.

JP 2015-124380 A

By the way, when cold air is circulated in the duct in a high-humidity environment, a problem may arise in that dew condensation water produced by dew condensation on the outer surface of the duct drips.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a duct capable of suppressing dripping of condensed water.

According to the present invention, there is provided a duct in which a non-woven fabric is integrally formed with a duct body, wherein the duct body is a foam blow molding.

In the duct of the present invention, the non-woven fabric is integrally formed with the duct body, which is a foam blow molded body, so dew condensation is less likely to occur on the surface of the duct body, and even if dew condensation occurs, the dew condensation water is absorbed by the non-woven fabric. Therefore, dripping of condensed water is suppressed.

In addition, when the nonwoven fabric is attached with an adhesive or the like, the nonwoven fabric may peel off from the duct main body when the nonwoven fabric repeatedly absorbs and dries the condensed water. Since the non-woven fabric is integrally formed with the main body, the non-woven fabric is prevented from being peeled off from the duct main body.

Various embodiments of the present invention are illustrated below. The embodiments shown below can be combined with each other.
Preferably, in the above-described duct, the duct has at least one of concave portions and convex portions on the surface on which the nonwoven fabric is provided.
Preferably, in the duct described above, the nonwoven fabric has an average 10% elongation load measured in two orthogonal directions of 5.5 N or less.
Preferably, in the duct described above, the nonwoven fabric has a basis weight of 170 g/cm ² or less.
Preferably, a method for manufacturing a duct using first and second molds, comprising a blow molding step, wherein a foamed parison is placed between the first and second molds, and With the nonwoven fabric placed between the first mold and the foamed parison, the first and second molds are closed, and air is introduced into the foamed parison trapped in the cavity between the first and second molds. It is a method of blowing in.
Preferably, in the method described above, the first mold has at least one of concave portions and convex portions in a portion facing the nonwoven fabric.
Preferably, in the method described above, the nonwoven fabric has an average 10% elongation load measured in two orthogonal directions of 5.5 N or less.
Preferably, in the method described above, the nonwoven fabric has a basis weight of 170 g/cm ² or less.

1 is a perspective view of a duct 1 of one embodiment of the invention; FIG. 1 shows an example of a molding machine 10 that can be used to manufacture the duct 1 of one embodiment of the present invention. 3 is an enlarged cross-sectional view of the vicinity of molds 21 and 22 in FIG. 2; FIG. 4 is a cross-sectional view showing a state in which molds 21 and 22 are closed from the state in FIG. 3; FIG. FIG. 3 is a perspective view of the structure 31 after removal from the molds 21 and 22 and removal of burrs 34;

Embodiments of the present invention will be described below. Various features shown in the embodiments shown below can be combined with each other. In addition, the invention is established independently for each characteristic item.

1. Duct 1
The duct 1 is preferably a vehicle duct arranged in an instrument panel or ceiling of a vehicle. In FIG. 1, the duct 1 does not have branches, but it may have branches. The duct 1 is provided with an opening 1c. The number of openings 1c may be two or three or more. A duct 1 comprises a duct body 2 and a nonwoven fabric 3.

The duct body 2 is a foam blow molding and can be manufactured by blow molding a foam parison 23 (shown in FIGS. 2-3). Such a duct body 2 is excellent in heat insulation and sound absorption.

The duct body 2 includes a tubular portion 2a and a plate-shaped flange portion 2b protruding from the tubular portion 2a. Air flows through the cylindrical portion 2a. The flange portion 2b is formed by compressing the foamed parison 23 with first and second molds 21 and 22 (shown in FIG. 3), and is provided on the parting line PL of the duct 1. As shown in FIG. The flange portion 2b is used to fix the duct 1 to another member. Examples of fixing methods to other members include mechanical fixing using screws or pins, seal fixing using an adhesive, vibration welding, and fixing by partially melting the material, and any fixing method may be used. The expansion ratio of the cylindrical portion 2a is, for example, 1.5 to 6 times, and specifically, for example, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4. 5, 5.0, 5.5, 6.0 times, and may be in the range between any two of the numerical values exemplified here.

The nonwoven fabric 3 is integrally formed with the duct body 2 . According to such a configuration, dew condensation is less likely to occur on the surface of the duct body 2, and even if dew condensation occurs, the dew condensation water is absorbed by the nonwoven fabric 3, so dripping of the dew condensation water is suppressed. In addition, by integrally molding the nonwoven fabric 3 with the duct body 2, scattering of fragments when the duct 1 is damaged is suppressed.

In addition, the integral molding can save the trouble of attaching the nonwoven fabric 3 to the duct body 2, and also has an anchoring effect (the nonwoven fabric 3 is fixed to the duct body 2 by the resin soaking into the nonwoven fabric 3) without using an adhesive. The nonwoven fabric 3 can be fixed to the duct body 2 by the effect of Further, in the case of integral molding, the duct body 2 and the nonwoven fabric 3 are strongly integrated, so even if the nonwoven fabric 3 repeats absorption of dew condensation water and drying, the nonwoven fabric 3 is prevented from peeling off from the duct body 2. be.

The nonwoven fabric 3 may be provided only on one side or both sides of the parting line PL. When the duct 1 is a ceiling duct, it is preferable to provide the nonwoven fabric 3 on the lower side when installed in the vehicle. In this case, scattering of fragments when the duct 1 is damaged is effectively suppressed.

For the purpose of avoiding interference between the duct 1 and other members, the duct 1 may be provided with at least one of the concave portion 1a and the convex portion 1b. If the surface on which the nonwoven fabric 3 is provided has recesses 1a or protrusions 1b, the nonwoven fabric 3 needs to be stretched in order to follow the shape of the recesses 1a or protrusions 1b. If the nonwoven fabric 3 is difficult to stretch, the nonwoven fabric 3 will not easily follow the concave portion 1a or the convex portion 1b, and the integration of the duct main body 2 and the nonwoven fabric 3 will be insufficient, resulting in a gap between the two. may be lost.

A 10% elongation load is given as an index of the ease of stretching the nonwoven fabric 3 . The 10% elongation load is the load when the nonwoven fabric 3 is stretched by 10%, and can be measured under the following conditions.
Test piece: 100mm x 150mm
Distance between chucks: 76.2mm
Test speed: 200mm/min
Chuck part dimensions: 25.4 mm x 25.4 mm

The nonwoven fabric 3 preferably has a 10% elongation load of 5.5N or less, more preferably 4.5N or less. This value is, for example, 1.0 to 5.5 N, specifically, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4 .5, 5.0, 5.5 N, and may be in the range between any two of the values exemplified herein. The 10% elongation load is preferably measured in two directions perpendicular to each other, the average value is preferably within the above range, and the measured values in both directions are preferably within the above range. The two directions are preferably the MD direction (extrusion direction of the foamed parison 23) and the TD direction.

The nonwoven fabric 3 preferably has a basis weight of 170 g/cm ² or less. This is because the smaller the basis weight, the smaller the load when the nonwoven fabric 3 is stretched. The basis weight is, for example, 50 to 170 g/cm ² , specifically, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170 g/cm ² , It may be in a range between any two of the numerical values exemplified here.

The nonwoven fabric 3 preferably has a thickness of 0.5 to 2.0 mm, more preferably 0.5 to 1.5 mm. If the nonwoven fabric 3 is too thin, the effect of absorbing condensed water and preventing scattering of fragments may be insufficient. be.

The ratio of the depth of the concave portion 1a or the height of the convex portion 1b to the thickness of the nonwoven fabric 3 is, for example, 3-30, preferably 5-25. Specifically, this value is, for example, 3, 5, 10, 15, 20, 25, 30, and may be within a range between any two of the numerical values exemplified here.

The nonwoven fabric 3 is preferably not provided on the flange portion 2b. This is because if the nonwoven fabric 3 is provided on the flange portion 2b, the fastening strength with other members tends to decrease, and the dimensional accuracy tends to decrease.

When the duct 1 is molded, the stamps may be transferred to the surface of the duct 1 by the molds 21 and 22 . Such an imprint is difficult to transfer to the nonwoven fabric 3 . For this reason, it is preferable not to provide the nonwoven fabric 3 on the part where the marking is made. Such a configuration can be realized, for example, by using the nonwoven fabric 3 having openings at the portions to be engraved.

The nonwoven fabric 3 may be composed of one sheet, or may be composed of a plurality of sheets. If the nonwoven fabric 3 is composed of a plurality of sheets, it is easy to form the nonwoven fabric 3 integrally when the surface on which the nonwoven fabric 3 is provided has a complicated shape.

2. Configuration of Molding Machine 10 A molding machine 10 that can be used to manufacture a foamed duct according to one embodiment of the present invention will be described with reference to FIG. The molding machine 10 includes a resin supply device 20 , a head 18 and first and second molds 21 and 22 . The resin supply device 20 includes a hopper 12 , an extruder 13 , an injector 16 and an accumulator 17 . The extruder 13 and the accumulator 17 are connected via a connecting pipe 25 . The accumulator 17 and the head 18 are connected via a connecting pipe 27 .
Each configuration will be described in detail below.

<Hopper 12, Extruder 13>
The hopper 12 is used to charge the raw material resin 11 into the cylinder 13 a of the extruder 13 . Although the form of the raw material resin 11 is not particularly limited, it is usually in the form of pellets. The raw material resin 11 is, for example, a thermoplastic resin such as polyolefin. The raw material resin 11 is fed from the hopper 12 into the cylinder 13a, and then heated in the cylinder 13a to be melted into a molten resin. In addition, it is conveyed toward the tip of the cylinder 13a by the rotation of the screw arranged in the cylinder 13a.

<Injector 16>
The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. The blowing agent injected from the injector 16 includes physical blowing agents, chemical blowing agents, and mixtures thereof, but physical blowing agents are preferred. As physical blowing agents, inorganic physical blowing agents such as air, carbon dioxide gas, nitrogen gas, and water, organic physical blowing agents such as butane, pentane, hexane, dichloromethane, and dichloroethane, and supercritical fluids thereof are used. be able to. The chemical blowing agent may be injected from hopper 12 instead of injected from injector 16 .

<Accumulator 17, Head 18>
A molten resin 11 a obtained by melt-kneading a raw material resin and a foaming agent is extruded from a resin extrusion port of a cylinder 13 a and injected into an accumulator 17 through a connecting pipe 25 . The accumulator 17 has a cylinder 17a and a piston 17b slidable inside the cylinder 17a, and the molten resin 11a can be stored in the cylinder 17a. By moving the piston 17b after a predetermined amount of the molten resin 11a is stored in the cylinder 17a, the molten resin 11a is extruded through the connecting pipe 27 from the die slit provided in the head 18 and suspended to form the foamed parison 23. to form The shape of the foamed parison 23 is not particularly limited, and may be cylindrical or sheet-like.

<First and second molds 21, 22>
A foam parison 23 is guided between the molds 21 and 22 . As shown in FIG. 3, the molds 21 and 22 have cavities 21a and 22a, and pinch-off portions 21b and 22b are provided to surround the cavities 21a and 22a. The cavities 21a, 22a are configured to take the shape of the structure 31 when the molds 21, 22 are closed. The mold 21 is preferably provided with a convex portion 21c and a concave portion 21d corresponding to the concave portion 1a and the convex portion 1b.

3. Foam Duct Manufacturing Method The foam duct manufacturing method of the present embodiment includes a molding step.

In the molding step, the molds 21 and 22 are closed while the foamed parison 23 is placed between the molds 21 and 22 and the nonwoven fabric 3 is placed between the first mold 21 and the foamed parison 23. Air is blown into a bag-shaped foamed parison 23 confined in cavities 21a and 22a between 21 and 22.例文帳に追加

The molding process includes, for example, a nonwoven fabric setting process, an extrusion process, a mold closing process, and a blow process.

In the nonwoven fabric setting step, the nonwoven fabric 3 is held in the mold 21 as shown in FIG. In the extrusion process, a foamed parison 23 is extruded between dies 21 and 22 . In the mold closing step, the molds 21, 22 are closed after the extrusion step to enclose a portion of the foamed parison 23 within the cavities 21a, 22a between the molds 21, 22. As shown in FIG. The parts of the foamed parison 23 that are confined within the cavities 21a and 22a are shaped like bags. In the blowing process, air is blown into the bag-shaped foamed parison 23 . At this time, the foamed parison 23 and the nonwoven fabric 3 are shaped along the surface shapes of the cavities 21a and 22a, and the resin forming the foamed parison 23 permeates into the nonwoven fabric 3, thereby integrating the foamed parison 23 and the nonwoven fabric 3. become.

By the above steps, as shown in FIG. 4, the foamed parison 23 is formed in the cavities 21a and 22a to form the foamed blow-molded body 32, and the non-woven fabric 3 is molded integrally with the foamed blow-molded body 32. As shown in FIG. Portions of the foamed parison 23 outside the pinch-off portions 21b and 22b become burrs 34. As shown in FIG.

FIG. 5 shows a state after the structure 31 having such a configuration is removed from the molds 21 and 22 and the burrs 34 are removed. By cutting off the bag portions 31a at both ends of the structure 31 from the state shown in FIG. By forming the structure 31 so that the bag portion 31a is not formed in the molding process, it is possible to omit the step of cutting the bag portion 31a.

During the molding process, the nonwoven fabric 3 is integrally molded with the foam blow molding 32 by the resin forming the foamed parison 23 soaking into the nonwoven fabric 3 . The higher the air blowing pressure in the molding process, the easier it is for the nonwoven fabric 3 to conform to the projections 21c and the recesses 21d. As a result, the foaming ratio of the foam blow molded body 32 becomes low. Therefore, in foam blow molding, it is not preferable to increase the blowing pressure of air. As described above, the nonwoven fabric 3 used in the present embodiment preferably has a 10% elongation load of 5.5 N or less in order to improve the followability of the nonwoven fabric 3 without increasing the air blowing pressure too high.

Using the molding machine 10 shown in FIG. 2, the duct 1 having the structure shown in Table 1 was produced under the conditions shown below.

The inner diameter of the cylinder 13a of the extruder 13 was 50 mm, and L/D=34. For the raw material resin, a propylene homopolymer (manufactured by Borealis AG, trade name "Daploy WB140") and long-chain branched polypropylene (manufactured by Japan Polypropylene Corporation, trade name "EX6000K") were used at a mass ratio of 30:70. and LDPE base masterbatch containing 20 wt% sodium hydrogen carbonate foaming agent as a nucleating agent (manufactured by Dainichiseika Kogyo Co., Ltd., trade name "Fine Cell Master P0217K") for 100 parts by mass of resin. .0 parts by weight and 1.0 parts by weight of an LLDPE base masterbatch containing 40 wt% carbon black as a colorant. The temperature of each part was controlled so that the temperature of the foamed parison 23 was 190 to 200.degree. The blowing agent was injected through injector 16 using _N2 gas. The injection amount of the foaming agent, the extrusion speed of the molten resin 11a, and the gap between the die slits of the head 18 were set so that the expansion ratio of the foamed parison 23 was 2.5 times and the average thickness was 2.5 mm.

The foamed parison 23 formed under the above conditions is placed between the first and second molds 21 and 22, and the nonwoven fabric 3 having a thickness of 1.0 mm is placed between the first mold 21 and the foamed parison 23. Blow molding was performed in this state to produce a structure 31 shown in FIG. Next, the duct 1 was obtained by cutting off the bag portions 31a at both ends of the structure 31 . In samples 1 to 6, nonwoven fabric 3 having a basis weight and a 10% elongation load shown in Table 1 was used.

The measurement conditions for the 10% elongation load are as follows.
Test equipment: Universal testing machine RTF-1325 manufactured by A&D Co., Ltd.
Test piece: 100mm x 150mm
Distance between chucks: 76.2mm
Test speed: 200mm/min
Chuck part dimensions: 25.4 mm x 25.4 mm

The resulting duct 1 was evaluated for moldability by visual observation and finger touch, and evaluated according to the following criteria.
◯: No gap was observed between the duct body 2 and the nonwoven fabric 3 (the shape of the cavity can be clearly transferred).
Δ: A gap was confirmed between the duct main body 2 and the nonwoven fabric 3 at the edge of the concave portion 1a or the convex portion 1b (specifically, the portion formed between the wall surfaces [the angle is 110° or less]) (cavity shape could not be transferred).
x: A gap was observed between the duct main body 2 and the nonwoven fabric 3 also at portions other than the edges of the concave portion 1a and the convex portion 1b (the shape of the cavity could not be transferred).

As shown in Table 1, samples 1 to 4 with a 10% elongation load of 5.5 N or less have good formability, and samples 1 to 3 with a 10% elongation load of 4.5 N or less have good formability. was particularly good.

Reference Signs List 1: Duct 1a: Concave portion 1b: Convex portion 1c: Opening 2: Duct main body 2a: Cylinder portion 2b: Flange portion 3: Nonwoven fabric 10: Molding machine 11: Raw resin 11a: Molten resin 12: Hopper 13: Extruder 13a: Cylinder 16: Injector 17: Accumulator 17a: Cylinder 17b: Piston 18: Head 20: Resin supply device 21: First mold 21a: Cavity 21b: Pinch-off portion 21c: Convex portion 21d: Concave portion 22: Second mold 22a: Cavity 22b : Pinch-off part 23 : Foam parison 25 : Connecting pipe 27 : Connecting pipe 31 : Structure 31a : Bag part 32 : Foam blow molding 34 : Flash

Claims (6)

A duct in which a non-woven fabric is integrally formed on a duct body,
The duct body is a foam blow molded body,
The nonwoven fabric has an average value of 10% elongation load measured in two orthogonal directions of 4.5 N or less,
The duct , wherein the nonwoven fabric has a thickness of 1.0 to 2.0 mm . A duct according to claim 1,
The duct has at least one of concave portions and convex portions on the surface on which the nonwoven fabric is provided. A duct according to claim 1 or claim 2 ,
The duct, wherein the nonwoven fabric has a basis weight of 170 g/cm ² or less. A method for manufacturing a duct using first and second molds,
Equipped with a blow molding process,
In the blow molding step, the foamed parison is placed between the first and second molds, and the first and second molds are closed with the nonwoven fabric placed between the first mold and the foamed parison. , blowing air into the foamed parison confined within the cavity between the first and second molds;
The nonwoven fabric has an average value of 10% elongation load measured in two orthogonal directions of 4.5 N or less,
The method , wherein the nonwoven fabric has a thickness of 1.0 to 2.0 mm . 5. The method of claim 4 , wherein
The method, wherein the first mold has at least one of a concave portion and a convex portion in a portion facing the nonwoven fabric. A method according to claim 4 or claim 5 ,
The method, wherein the nonwoven fabric has a basis weight of 170 g/cm ² or less.

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