JP7310679B2 - air conditioning duct - Google Patents

Description

TECHNICAL FIELD The present invention relates to an air conditioning duct, which is a ventilation pipe of an air conditioner installed in a vehicle (automobile, train, airplane, ship, etc.), building, or the like.

Most air conditioning ducts are seamless pipes formed by extrusion molding of resin, but there are also pipes with joints formed by joining a plurality of duct members divided in the circumferential direction of the duct. As an example of the latter, in Patent Document 1, a portion of the back surface of a plate-like base material for a molded ceiling of an automobile and both edge surfaces of a duct member having a U-shaped cross section are adhered with an adhesive. An air conditioning duct (roof duct) is described. Since part of the plate-shaped base material is also used as one of the duct members forming part of the circumferential direction of the duct, installation space and materials can be reduced.

In addition, Patent Document 1 is characterized in that the adhesive is heated and softened by residual heat when the raw sheet for the resin base material is molded, and the adhesive includes a hot melt adhesive and a thermosetting adhesive. , one-component reactive adhesives, two-component reactive adhesives, etc. can be used.
Of these, thermosetting, one-part reaction, and two-part reaction adhesives cure only by chemical reaction, so the curing time is long, and in the semi-cured state, there is a possibility that the parts may fall off, making it difficult to handle the product. workability and manufacturing efficiency are not good.
Hot-melt adhesives, on the other hand, harden when cooled, so the curing time is shorter than thermosetting, one-component, and two-component adhesives, making it possible to handle products quickly. Therefore, workability and manufacturing efficiency are good.

JP 2007-038531 A

Warm air flows through the air conditioning duct during heating. On the other hand, hot-melt adhesives are thermoplastic and therefore weak against heat. However, until now, heat has not been a problem when using hot melt adhesives in air conditioning ducts. It is presumed that it was thought that hot-melt adhesives would not soften or melt at temperatures as warm as air.

However, according to the studies of the present inventors, for example, in the case of an air-conditioning duct for an automobile, the portion arranged on the dashboard or center console near the air-heating part (e.g., heater core) of the air-conditioning system is located on the roof farther from the air-heating part. It has been found that hot-melt adhesives can soften or melt and become less adhesive due to the flow of hotter air compared to the portion located at the top. Depending on the extent of the decrease in adhesive strength, it may lead to separation between the duct members, so it is necessary to take countermeasures.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an air conditioning duct in which the adhesive layer does not soften or melt even when high-temperature air flows, and the duct members do not separate.

[1] Air-conditioning duct An air-conditioning duct in which a plurality of duct members divided in the circumferential direction of the duct are adhered with an adhesive layer interposed between the duct members,
The plurality of duct members are made of polyolefin resin,
The adhesive layer is made of an olefin hot melt adhesive,
The open time of the olefin hot melt adhesive is 5 to 60 seconds,
In accordance with JIS K7198, a disk-shaped test piece with a diameter of 10 mm and a thickness of 1 to 2 mm was used for the olefin hot melt adhesive after curing, using a φ 10 mm parallel plate as the geometry, and the test temperature was 20 to 180 ° C. , a strain rate of 2%, a frequency of 50 Hz, a dynamic viscoelasticity test at a temperature increase rate of 5 ° C./min and a storage modulus (G') at 80 ° C. of 40 kPa or more,
An air-conditioning duct characterized by an adhesive layer having a shear adhesive strength (JIS K6850) of 0.05 MPa or more between duct members at 80°C.

Here, the shear adhesive strength is preferably 0.09 MPa or more.

The air-conditioning duct is preferably an automobile air-conditioning duct that is disposed within a distance of 2 m from the air heating portion of the air conditioner of the automobile. This is because the present invention, which is excellent in adhesiveness at high temperatures, is particularly suitable for this portion, since freshly heated high-temperature air flows through the air heating portion. Examples of the air heating unit include a heater core, a heat pump heat exchanger, a positive temperature coefficient (PTC) heater, a fuel heater, and the like. A dashboard or a center console can be exemplified as the part.

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Olefin-based hot-melt adhesives are cured by cooling, so the curing time is shorter than that of thermosetting, one-component, and two-component reaction adhesives. Moreover, the present invention uses a hot-melt adhesive with an open time of 60 seconds or less, so that the curing time is particularly short. As a result, the cycle time can be shortened, and the number of work-in-progress products can be reduced, enabling efficient production.

Furthermore, the present inventors have found out the following items (a) to (d) through intensive studies.
(a) Since the hot-melt adhesive has an open time of 5 seconds or more, stringiness can be prevented when the adhesive is applied in a bead shape (string shape).
(b) The hot-melt adhesive has an open time of 60 seconds or less, thereby satisfying the requirements for high-temperature adhesiveness. The reason for this is thought to be that an adhesive with a short open time is less likely to soften at high temperatures because it is presumed that the amount of plasticizer compounded is small.
(c) The hot-melt adhesive has a storage elastic modulus of 40 kPa or more at 80° C., thereby satisfying the requirements for high-temperature adhesion. The reason for this is thought to be that the adhesive needs to have cohesive strength at the high temperature evaluation temperature (assumed temperature during use), and thus must be hard.
(d) With the above (b) and (c), the shear adhesive strength (JIS K6850) at 80° C. between the duct members by the adhesive layer can be 0.05 MPa or more. It does not soften or melt even if the gas flows, and the plurality of duct members do not separate.

According to the present invention, it is possible to provide an air conditioning duct in which the adhesive layer does not soften or melt even when high-temperature air flows, and the duct members do not separate.

FIG. 1 is a graph showing the storage modulus of adhesives (after curing) used in Examples and Comparative Examples at a test temperature of 20 to 180.degree. FIG. 2 is a perspective view of both member adhesion test pieces for measuring the shear adhesive strength of Examples and Comparative Examples. FIG. 3 is a graph showing the relationship between the measured shear bond strength and the open time of the adhesive. FIG. 4 is a cross-sectional view showing an air conditioning duct of an embodiment and a manufacturing method thereof. FIG. 5 is a cross-sectional view showing an embodiment of an air conditioning duct installed in the center console of an automobile.

1. Duct Member Although the plurality of duct members is not particularly limited, the following aspects (a) and (b) can be exemplified.
(a) A mode in which the plurality of duct members is a combination of a plate-shaped duct member and a channel-shaped duct member having a U-shaped, U-shaped, C-shaped, or V-shaped cross section Plate-shaped duct member is not limited to a member dedicated to the duct, and may be a part of a plate-like member (for example, base material) of another functional product. Examples of the plate-like member include a plate-like base material for a center console of an automobile, a plate-like base material for a molded ceiling, and the like.
(a) Multiple duct members are combinations of channel-shaped duct members and channel-shaped duct members

The polyolefin-based resin of the duct member is not particularly limited, but examples include polypropylene (PP), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), polymethylpentene (TPX), and the like. The plurality of duct members may be made of the same polyolefin resin or may be made of different polyolefin resins.

2. Adhesive Layer The shape of the adhesive layer is not particularly limited, but may be a planar shape, a bead shape, or the like.
The thickness of the adhesive layer is not particularly limited, but can be exemplified from 0.1 to 1 mm.

Next, embodiments of the present invention will be described with reference to the drawings. The structure, material, shape and dimensions of each part in the embodiment are examples, and can be changed as appropriate without departing from the gist of the invention.

A plate-like first member made of PP material used for the first duct member of the air-conditioning duct described later and a plate-like second member made of PE material used for the second duct member were produced. These first member and second member were adhered with various adhesives shown in the following Table 1, and each test piece of Examples 1 to 5 and Comparative Examples 1 to 5 corresponding to the adhesion portion of the air conditioning duct was obtained. It was prepared and the shear adhesive strength was measured. In addition, the open time, storage elastic modulus, etc. of each adhesive were measured. Details will be described in order below.

[First member]
A solid plate-shaped first member having a thickness of 3 mm was molded from PP.
As the PP, TSOP5 (trade name “Prime Polypro LA880G” manufactured by Prime Polymer Co., Ltd.) was used. The composition of the PP is 74% by mass of resin (ethylene/propylene copolymer), 5% by mass of rubber (ethylene/α-olefin copolymer), 20% by mass of talc (powder), and 0.0% of other (additives, etc.). 5% by mass.

[Second member]
A closed-cell foam plate-like second member having a thickness of 3 mm was molded from PE foam.
As the foamed PE, the trade name "Softlon NF" manufactured by Sekisui Chemical Co., Ltd. was used. The composition of the foamed PE is 90% by mass or more of resin (olefin resin) and 2% by mass or less of carbon black.

[glue]
The trade names and main components of adhesives used in Examples and Comparative Examples are as follows.
Example 1: Trade name “RAC-60” manufactured by MORESCO (main component: olefin resin)
Example 2: Trade name “RAC-90” manufactured by MORESCO (main component: olefin resin)
Example 3: Trade name “Asahi Tac FR590” manufactured by Asahi Chemical Synthetic Co., Ltd. (main component: α-olefin copolymer)
Example 4: Trade name “swifttherm 2699” manufactured by Sekisui Fuller Co., Ltd. (main component: olefin resin)
Example 5: Trade name “swifttherm 2003” manufactured by Sekisui Fuller Co., Ltd. (main component: olefin resin)
Comparative Example 1: Trade name “SX-PPK1000” manufactured by Cemedine (main component: acrylic-modified silicone)
Comparative Example 2: Trade name “PPX+PPX-3” manufactured by Cemedine (main component: cyanoacrylate)
Comparative Example 3: Trade name “Scotch-WeldDP-8010Blue” manufactured by 3M (main component: acrylic resin)
Comparative Example 4: Trade name “RAC-22Z” manufactured by MORESCO (main component: olefin resin)
Comparative Example 5: Trade name “Asahi Tac AB5415” manufactured by Asahi Chemical Synthetic Co., Ltd. (main component: α-olefin copolymer)
Here, the adhesive used in Examples 1 to 5 and Comparative Examples 4 and 5 was an olefin hot melt adhesive, and the adhesive used in Comparative Example 1 was a one-liquid reactive adhesive (moisture curing). , the adhesive used in Comparative Example 2 is a one-component reactive adhesive (instant type), and the adhesive used in Comparative Example 3 is a two-component reactive adhesive.

[Characteristics of adhesive before curing]
(1) Measurement of Open Time The open time of each adhesive was measured according to JAI-7 (Japan Adhesive Industry Association Standard) "Test Method for Hot Melt Adhesives".
Specifically, each adhesive was applied to an adhesive test piece made of K liner B flute (220 g/m ² ) corrugated cardboard, at room temperature 23 ° C ± 2 ° C, application temperature 180 ± 2 ° C, adhesive area 5000 mm ² (adhesion width 50 mm × Bonding depth 100 mm), applied with a coating amount of 3 ± 0.3 g / m, and then released after pressing with a pressing pressure of 2 kgf x pressing time of 2 seconds, when 80% or more of the material breaks. time was measured. Table 1 shows the results.

(2) Curing Time Table 1 shows the curing time published as product information for each adhesive of Comparative Examples 1-3. Since hotmelts solidify when cooled, their curing time is not much different from the open time.

[Characteristics of adhesive after curing]
(3) Measurement of storage modulus In accordance with JIS K7198 "Test method for temperature dependence of dynamic viscoelasticity", each adhesive after curing (diameter 10 mm, thickness 1 to 2 mm Disc-shaped test piece ) was measured.
Specifically, using a "stress-controlled rheometer AR2000ex" manufactured by TA Instruments, using a φ10 mm aluminum parallel plate as a geometry, a test temperature of 20 to 180 ° C., a strain rate of 2%, a frequency of 50 Hz, and a heating rate of 5 ° C./ A dynamic viscoelasticity test was performed at 10 minutes to measure the storage modulus. The results are shown in FIG. 1, and Table 1 shows the respective storage elastic moduli at 23° C. and 80° C.

[Adhesion performance]
(4) Measurement of shear bond strength of both member adhesion test pieces In accordance with JIS K6850 "Adhesive - Test method for tensile shear bond strength of rigid adherend", Examples 1 to 5 and Comparative Examples 1 to 5 An adhesive test piece for both members was prepared, and the shear adhesive strength was measured by applying a tensile shear load parallel to the adhesive surface.
Specifically, as shown in FIG. 2, the first member and the second member are cut into strips of 100 mm × 25 mm, and between the overlapped ends of both members, "hot melt applicator Dynamelt SR05" manufactured by ITW Dynatech Co., Ltd. ”, each adhesive is applied at a tank temperature of 180 ° C., a nozzle temperature of 180 ° C., an adhesion area of 250 mm ² (adhesion width 25 mm × adhesion depth 10 mm), and an adhesion thickness of 0.1 to 0.3 mm, After clamping between the ends with a clamping force of about 2 kg × clamping time of 5 to 10 seconds, it is released and left at 20 ° C. and 50% Rh for 24 hours (curing) to prepare an adhesion test piece for both members. bottom. Then, the end portion chucking range of the first member and the end portion chucking range of the second member are chucked with a chuck jig so that the distance between the jigs is 112.5 mm and the distance from the end of the bonding portion to the chucking position is 50 mm. Then, it was pulled in the opposite direction at a pulling speed of 50 mm/min, and the shear bond strength was measured. The results are shown in FIG.

[evaluation]
As shown in Table 1, Comparative Example 1 (using a one-component reactive adhesive) and Comparative Example 3 (using a two-component reactive adhesive) had high shear adhesive strength at 80°C, but the curing time was 3. , 600 to 10,800 seconds or 86,400 seconds, which is inefficient for production use.
Comparative Example 2 (using a one-liquid reactive adhesive (instantaneous type)) has a high shear adhesive strength at 80° C., but a short open time of 2 to 3 seconds.

Further, Comparative Examples 4 and 5 (using a hot melt adhesive) have a long open time of 180 seconds, a low storage modulus of 15 or 14 kPa at 80 ° C., and a shear adhesive strength of 0.03 or 0 at 80 ° C. It was as low as 0.02 Mpa. Even hot melt adhesives with a long open time are presumed to have a large amount of plasticizer, and those with a low storage elastic modulus at high temperatures are soft at high temperatures, so they satisfy the adhesiveness requirements at high temperatures. Not likely.
On the other hand, Examples 1 to 5 (using hot melt) have an open time in the range of 5 to 60 seconds, a storage modulus at 80 ° C. of 40 kPa or more, and a shear adhesive strength at 80 ° C. It was 0.05 Mpa or more (especially 0.09 Mpa or more in Examples 1 to 4).

Based on this result, an open time within the range of 5 to 60 seconds is evaluated as ◯ (good), and an open time outside the range is evaluated as x (improper). A storage elastic modulus of 40 kPa or more at 80° C. is evaluated as ◯ (good), and a storage modulus of less than 40 kPa is evaluated as x (improper). A shear bond strength of 0.05 MPa or more at 80° C. is evaluated as ◯ (good), 0.09 MPa or more as ⊚ (best), and less than 0.05 MPa as x (improper). If there is even one item with an X, it will be x (improper). .

[Air conditioning duct]
Using the constructions of Examples 1 to 5, air conditioning ducts of the Examples as shown in FIGS. 4 and 5 can be manufactured.
This air-conditioning duct 1 is arranged in a center console 10 within a distance of 2 m from an air heating part (for example, a heater core) under the dashboard of an air-conditioning system in an automobile. It is for blowing conditioned air 14 toward the thigh 13 of 12 .

The air-conditioning duct 1 is divided into two parts in the circumferential direction of the duct. It is a square tube-shaped one adhered by an adhesive layer 4 . The plate-shaped first duct member 2 is not a dedicated duct member, but a part of a plate-shaped base material forming the side portion of the center console 10 . Since a part of the plate-shaped base material is also used as one of the duct members forming a part of the duct in the circumferential direction, the installation space and materials can be reduced. A blowout port 5 is formed in the first duct member 2 .

The first duct member 2 is made of the same PP as in Examples 1 to 5, the second duct member 3 is made of the same foamed PE as in Examples 1 to 5, and the adhesive layer 4 is made of the olefin hot glue of Examples 1 to 5. A melt adhesive is appropriately selected and used.
Therefore, the open time of the olefin-based hot melt adhesive is 5 to 60 seconds, the storage elastic modulus (G′) of the adhesive layer 4 at 80° C. is 40 kPa or more, and the duct members 2 and 3 made of the adhesive layer 4 Shear adhesive strength (JIS K6850) at 80° C. between is 0.05 MPa or more.

An example of the manufacturing method of this air conditioning duct 1 will be described. As shown in FIG. 4, an adhesive layer 4 is formed by applying an olefinic hot-melt adhesive to the joint surface of the first duct member 2 . The heat-softened PE sheet is formed into a channel shape using a mold 21 to form the second duct member 3 . The joint end surface of the second duct member 3 is pressed against the first duct member 2 and attached. The adhesive layer 4 on the first duct member 2 is softened by the residual heat of the second duct member 3 and hardened by being cooled to room temperature, so that the two duct members 2 and 3 are adhered by the adhesive layer 4. .

It should be noted that the present invention is not limited to the above-described embodiments, and can be embodied with appropriate modifications without departing from the gist of the invention.

Reference Signs List 1 air-conditioning duct 2 first duct member 3 second duct member 4 adhesive layer 5 outlet 10 center console 11 seat 12 passenger 13 thigh 14 conditioned air 21 mold 22 mold

Claims (6)

An air conditioning duct in which a plurality of duct members divided in a plurality in the duct circumferential direction are adhered by an adhesive layer interposed between the duct members,
The plurality of duct members are made of polyolefin resin,
The adhesive layer is made of an olefin hot melt adhesive,
The open time of the olefin hot melt adhesive is 5 to 60 seconds,
In accordance with JIS K7198, a disk-shaped test piece with a diameter of 10 mm and a thickness of 1 to 2 mm was used for the olefin hot melt adhesive after curing, using a φ 10 mm parallel plate as the geometry, and the test temperature was 20 to 180 ° C. , a strain rate of 2%, a frequency of 50 Hz, a dynamic viscoelasticity test at a temperature increase rate of 5 ° C./min and a storage modulus (G') at 80 ° C. of 40 kPa or more,
An air-conditioning duct characterized by an adhesive layer having a shear adhesive strength (JIS K6850) of 0.05 MPa or more between duct members at 80°C. 2. The air conditioning duct according to claim 1, wherein said shear bond strength is 0.09 MPa or more. 3. The air conditioning duct according to claim 1, wherein the plurality of duct members are a combination of a plate-shaped duct member and a channel-shaped duct member. 3. The air conditioning duct according to claim 1, wherein the plurality of duct members are a combination of channel-shaped duct members and channel-shaped duct members. 5. The air conditioning duct according to any one of claims 1 to 4, wherein the air conditioning duct is an automotive air conditioning duct disposed within a distance of 2 m from an air heating unit of an air conditioner in an automobile. 6. The air conditioning duct according to claim 5, wherein said portion is a dashboard or center console of an automobile.

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