JP6835357B2 - Resin duct - Google Patents

Description

The present invention relates to a resin duct used for a ventilation / air conditioning duct of a house, which is rich in flexibility, has good workability, and has a small pressure loss.

Conventionally, in order to reduce the pressure loss due to friction between the fluid and the solid surface through which the fluid flows, a technique for imparting unevenness to the solid surface through which the fluid flows has been studied. In particular, in the housing industry, many systems that ventilate and air-condition by passing air through the duct are adopted, and there is a strong demand for reducing the pressure loss of the duct that is piped in the house in all directions. By reducing the pressure loss of the duct, the ventilation / air conditioning system used can be miniaturized, energy saving, and expansion of the living space can be expected. At the same time, from the viewpoint of shortening the construction period and work safety, the duct is required to be lightweight and excellent in operability.

As a hose in which a technique for reducing pressure loss is used on a solid surface through which a fluid flows, Patent Document 1 describes a hose having square irregularities on the inner pipe surface perpendicular to the pipe axis direction, and at the time of burying. In order to withstand the soil pressure applied from the outside, a resin having a property (rigidity) that is not easily deformed by an external force, for example, a resin such as nylon 12 is used. However, when a rigid resin is used, the flexibility is not satisfactory for use as a ventilation / air-conditioning pipe for a house, and the cutting work is difficult, so that the workability is not satisfactory. In addition, since it has square irregularities, dust and dirt tend to collect in the recesses, which leads to the generation of mold in the duct, so it is satisfactory for use in applications that cannot be easily cleaned, such as houses. is not it.
Patent Document 2 describes a pipe having triangular irregularities parallel to the pipe axis on the inner pipe surface of the hard resin pipe, but since it is a hard resin pipe, it is not flexible and cutting work is difficult. Therefore, it is not satisfactory from the viewpoint of flexibility and workability when used as a ventilation / air conditioning pipe for a house. In addition, since the pitch of the unevenness is narrow, the pressure loss characteristics are not satisfactory for use as piping for ventilation and air conditioning in a house.
Further, Patent Document 3 describes a technique of a flexible pipe material using a non-woven fabric, and since the non-woven fabric is used, flexibility and workability are satisfactory. However, in order to reduce the pressure loss, it is preferable that the inner surface is flat with no unevenness, so that the pressure loss characteristics are not satisfactory for use as a ventilation / air conditioning pipe for a house.

JP-A-2002-188762 Japanese Unexamined Patent Publication No. 4-351389 Japanese Unexamined Patent Publication No. 2014-129838

An object of the present invention is to provide a resin duct which is rich in flexibility, has good workability, and has a small pressure loss.

As a result of diligent studies to achieve the above object, the present inventors have formed a meat portion made of a band-shaped body including at least a non-woven fabric and a ring-shaped or spiral core material made of a thermoplastic hard resin, and the inner surface has specific unevenness. The present invention has been completed by finding that a resin duct having a shape can reduce pressure loss.

That is, the present invention is a resin duct composed of at least a meat portion made of a strip containing a non-woven fabric and a spiral core material made of a thermoplastic hard resin, and satisfying the structures (1) and (2) below. (1) When the repeating unit of the apex of the convex portion on the inner surface of the duct is X (mm), 5 mm ≦ X ≦ 25 mm.
(2) When the depth of the depression between the protrusions on the inner surface of the duct is Z (mm) and the inner diameter of the duct is ID (mm), 0.01 ≦ Z / ID ≦ 0.05.

Further, the present invention is preferably the above-mentioned resin duct in which the thermoplastic hard resin is an olefin-based thermoplastic resin, and more preferably the above-mentioned resin duct in which a heat insulating layer is further laminated on the outside of the resin duct.

Since the resin duct of the present invention has a specific uneven shape on the inner surface, the pressure loss of the fluid is reduced. Therefore, when selecting a ventilation / air conditioning system, it is possible to make it smaller, save energy, and expand the living space.

A partial cross-sectional schematic diagram showing one of the preferred embodiments of the resin duct of the present invention.

FIG. 1 is a partial cross-sectional schematic view showing one of the preferred embodiments of the resin duct of the present invention. The resin duct has a tube meat portion and heat in a band state in which a resin film is laminated on one side or both sides of a non-woven fabric. A spiral core material made of a plastic hard resin is integrated by melt bonding.

As the non-woven fabric constituting the meat portion made of the strip-shaped body of the resin duct of the present invention, the core material is formed of synthetic fibers obtained from a fiber-moldable thermoplastic resin such as polypropylene, polyethylene, or polyethylene terephthalate. It is preferable in terms of welding adhesion and recycling. In particular, from the viewpoint of flexibility, versatility, and processability, a non-woven fabric consisting of a mixed spun fiber of polypropylene and polyethylene or a composite spun fiber in which polyethylene is present on the fiber surface or a mixture of polyethylene fiber and polypropylene fiber. Non-woven fabric, a mixed spun fiber of polyethylene terephthalate and polyethylene, or a non-woven fabric made of a composite spun fiber in which polyethylene is present on the fiber surface, or a non-woven fabric made of a mixture of polyethylene fiber and polyethylene terephthalate fiber has duct formability. Is the best. In this case, the low melting point polymer or the low melting point polymer fiber acts as a heat binder component to fix the shape of the non-woven fabric and further provide heat-sealing property with the core material. In particular, a fiber composed of a low melting point polymer and a high melting point polymer, such as a composite spinning fiber or a mixed spinning fiber using the above-mentioned polyethylene component as a low melting point component, and a fiber in which the low melting point polymer is present on the fiber surface is a thermal binder fiber. It is also a good example to use as. In this case, the low melting point polymer existing on the fiber surface melts and adheres to the core material.

It is also possible to use inorganic fibers such as glass fiber and rock wool as the fibers constituting the non-woven fabric, but the inorganic fibers are preferable because the fiber cut pieces are scattered in the air at the time of cutting, which causes deterioration of the working environment. It can not be said. Further, when a large impact is applied during work or after installation, the fiber pieces of the inorganic fibers may invade the duct in some cases and may be mixed with the gas in the duct, which is not preferable.

The basis weight of the nonwoven fabric may include the 30 to 200 g / m ^2, and more are preferred those 70~120 g / m ^2. The non-woven fabric may be any of spunbonded non-woven fabric, melt blown non-woven fabric, wet non-woven fabric, water-related non-woven fabric, needle punch non-woven fabric and the like, but spun-bonded non-woven fabric is particularly preferable from the viewpoint of strength. The thickness of the constituent fibers is preferably in the range of 1 to 5 dtex from the viewpoint of duct moldability.

If it is desired to prevent the pipe meat portion from protruding to the inner surface of the duct when the resin duct is bent, a resin film may be laminated on both sides or one side of the non-woven fabric. The resin film to be laminated on the non-woven fabric is preferably made of an olefin resin. The thickness of the film to be laminated is not limited as long as it has flexibility, but when flexibility is important, the thickness is preferably 100 μm or less.

Examples of the resin constituting the core material of the resin duct of the present invention include polyolefin resins such as polypropylene and polyethylene, polyester resins typified by polyethylene terephthalate, polyamide resins typified by nylon 6, and vinyls such as acrylic and polystyrene. Examples thereof include thermoplastic resins such as based resins, and among them, hard thermoplastic resins composed of carbon atoms and hydrogen atoms, or these atoms and oxygen atoms are preferable, and polyethylene, polyester, polypropylene, etc. are typically used. Examples include polypropylene. In particular, polypropylene and polyethylene are preferable from the viewpoint of hardness, weather resistance, versatility, etc., and polyethylene is more suitable.

The uneven shape of the inner surface of the duct satisfies the following (1) and (2) when the duct is unfolded in the length direction.
(1) When the repeating unit of the apex of the convex portion on the inner surface of the duct is X (mm), 5 mm ≦ X ≦ 25 mm,
(2) When the depth of the depression between the protrusions on the inner surface of the duct is Z (mm) and the inner diameter of the duct is ID (mm), 0.01 ≦ Z / ID ≦ 0.05.

In the above (1), the resin duct in which the repeating unit X (mm) of the apex of the convex portion on the inner surface of the duct is in the above range has a small fluid pressure loss. However, when the repeating unit X (mm) is less than 5 mm, the shape of the convex portion becomes sharp, so that the pressure loss becomes large and the resistance when flowing the fluid increases, which is not appropriate. On the other hand, if it exceeds 25 mm, the pressure loss becomes large and the resistance when flowing the fluid increases, which is not appropriate.
More preferably, the repeating unit X (mm) is between 5 and 13 (mm).

The repeating unit X (mm) of the convex apex of the inner surface of the duct developed in the length direction is obtained by observing with a microscope or a graduated loupe having a magnification of 8 times or more and measuring the distance between the convex apex. be able to.

In the above (2), the resin duct in which the depth Z (mm) of the depression between the protrusions on the inner surface of the duct is in the above range has a small fluid pressure loss.
However, when the relationship Z / ID between the depth Z (mm) of the depression and the inner diameter ID (mm) of the duct is less than 0.01, the inner surface is almost flat and uneven even when the inside of the pipe is touched with a fingertip and observed. Is not appropriate because it turns out that there is almost no such thing, and the pressure loss of the fluid increases and the resistance when the fluid flows increases. Further, when the relationship Z / ID between the depth Z (mm) of the depression and the inner diameter ID (mm) of the duct exceeds 0.05, the pressure loss of the fluid increases and the resistance when the fluid flows increases, which is appropriate. Not.
The relationship Z / ID between the depth Z (mm) of the recess and the inner diameter ID (mm) of the duct is preferably in the range of 0.015 to 0.023, and further in the range of 0.018 to 0.023. Is more preferable.

For the depth Z (mm) of the depression between the convex parts inside the duct, the cross-sectional shape of the duct developed in the length direction was observed with a microscope with a magnification of 10 times, and the vertices of three or more convex parts were connected. It can be determined by measuring the distance between the line and the line connecting the deepest points of two or more recesses.
Further, the duct inner diameter ID (mm) is a value measured by inserting a taper gauge having a minimum scale of 0.1 mm into the hose (distance between the convex portions facing each other on the inner surface of the duct), and the depth Z of the recess obtained above ( It can be obtained by adding a value twice as large as (mm).

By coating the resin duct with a heat insulating material, it is possible to obtain a resin duct having heat insulating properties. The heat insulating layer is for preventing the heat of the gas flowing in the resin duct from being taken to the outside or being transferred to the inside of the resin duct, and the heat insulating material is made of polyurethane foam or polyethylene foam. Thermoplastic foams such as, thermoplastic fiber materials such as felt made of polyethylene fiber and polyester fiber, and inorganic fiber material made of glass fiber and rock wool are used. Among them, from the viewpoint of flexibility and safety of the working environment, it is preferable to use a thermoplastic fiber material such as felt made of polyethylene fiber or polyester fiber.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. In the following examples and comparative examples, flexibility, workability, pressure loss measurement and evaluation were performed as follows.

<Evaluation of flexibility>
(1) A resin duct having a length of 2 m is installed in a straight tubular shape, and the terminal on one side thereof is fixed. Next, the terminal on the non-fixed side is gradually bent toward the fixed terminal side, and is bent until just before the resin duct is flattened. The bending radius r (mm) of the resin duct in that state is measured.
(2) The flexibility was evaluated according to the following criteria. The ID represents the inner diameter of the duct (mm).
◯: r ≦ 2 × ID (good flexibility and easy handling during construction)
Δ: 2 × ID <r ≦ 3 × ID (There is some difficulty in handling during construction, but there is no problem in construction)
×: 3 × ID <r (poor flexibility, not suitable for use as a duct)

<Evaluation of workability>
The workability was evaluated by combining the evaluation of the flexibility with the evaluation of the cutability of the duct.
The cutability of the duct was evaluated according to the following criteria.
1. 1. Is the tool used for cutting a general tool represented by scissors or a cutter? ○: Cutting work is possible with a general tool ×: Cutting work cannot be performed without using a special tool. Is the number of tools used for cutting small? ○: Can be cut with one tool ×: Use two or more tools For workability evaluation, use the results of flexibility evaluation and cutability evaluation. The evaluation was made according to the following criteria.
○: All three evaluated items are ○
×: There is at least one △ or × result among the evaluated items.

<Pressure loss: Measurement of friction loss coefficient (λ) during straight pipe>
(1) A resin duct with a length of 3 m is installed in a straight tube, and a blower / exhaust fan ("SJF-250-2") manufactured by Suiden Co., Ltd. is attached to the terminal on one side of the duct, and 0.5 m inside from both ends of the duct. Make a hole of Φ8mm in the place and attach the differential pressure gauge. Next, the air volume generated from the blower / exhaust fan is changed stepwise, and the pressure difference ΔP (Pa) and the equivalent flow velocity V (m / sec) at that time are measured.
(2) Using the equivalent flow velocity V (m / sec) measured by the method (1) above and the cross-sectional area A (m ² ) of the hose, the value of the air flow rate Q (m ³ / hour) is calculated by the equation (1). ).
Equation (1) Air volume Q = 3,600 x V x A
(3) From the value of the air volume Q (m ³ / hour) calculated in (2) above and the value of the pressure difference ΔP (Pa), the value of the air permeability a (m ³ / hour / Pa ^1/2 ) is expressed by the formula. Calculate according to (2).
Equation (2) Ventilation rate a = Q / ΔP ^1/2
(4) The pressure loss coefficient ζ is calculated according to the equation (3) using the value of ^{the air permeability a (m 3} / hour / Pa ^1/2 ) calculated in the above (3).
Equation (3) Pressure loss coefficient ζ = 2 / [ρ (a / 3,600) ² ]
In addition, ρ represents an air density (kg / m ³ ).
(5) Using the pressure loss coefficient ζ calculated in (4) above, the friction loss coefficient λ at the time of straight pipe is calculated according to the equation (4).
Equation (4) Friction loss coefficient λ = (ID × ζ) / L
The ID is the inner diameter of the duct (m), and L is the length of the duct (m).
(6) The friction loss coefficient λ for straight pipes was evaluated according to the following criteria.
⊚: 0.020 <λ ≦ 0.045 (friction between the fluid and the inner pipe surface is small, and there is almost no pressure loss of the fluid)
◯: 0.045 <λ ≦ 0.060 (There is some friction between the fluid and the inner pipe surface, but there is no problem with the pressure loss of the fluid when using the hose)
Δ: 0.060 <λ ≦ 0.080 (There is friction between the fluid and the inner pipe surface, and a decrease in the flow rate due to the pressure loss of the fluid is observed when using the hose)
×: 0.080 <λ (Since the friction between the fluid and the inner pipe surface is large, the pressure loss of the fluid is also large when using the hose, which is not suitable for using the hose)

<Example 1>
(1) A strip-shaped body (“KD5030WN” manufactured by Shinwa) in which polyethylene is bonded to both sides of a polyester non-woven fabric cut to a width of 30 mm is spirally wound on a pipe making machine having an outer diameter of 54.5 mm and adjacent to the strip-shaped body. A tube meat portion was formed by heat-sealing the side edges to each other with hot air at 500 ° C.
(2) Subsequently, on the same tube making machine as in (1) above, HDPE (“HY540” made by Nippon Polyethylene) is squeezed into a single-screw extruder (40 mmφ, cylinder temperature = 200 ° C, die temperature = 230 ° C). The hose-shaped molded product is cooled to 60 ° C by applying cold air and water from the outside of the pipe making machine to the strip-shaped body, and then removed from the pipe making machine and air-cooled to have an inner diameter of 53. A resin duct of Example 1 having 2 mm, a repeating unit of the convex portion X = 8 mm, and Z / ID = 0.012 was obtained.

<Example 2>
A molded product was obtained through the same steps as in Example 1. At this time, by weakening the twist of the spring-shaped rotating rod of the pipe making machine, the repeating distance of the convex portion was set to 5 mm. The hose-shaped molded product is cooled to 70 ° C by applying cold air and water from the outside of the pipe making machine, and then removed from the pipe making machine and air-cooled to have an inner diameter of 52.7 mm and a repeating unit of the convex portion X =. A resin duct of Example 2 having 5 mm and Z / ID = 0.017 was obtained.

<Example 3>
A molded product was obtained through the same steps as in Example 1. After cooling the hose-shaped molded product to 50 ° C by applying cold air and water from the outside of the pipe making machine, the hose-shaped molded product is removed from the pipe making machine and air-cooled to have an inner diameter of 53.4 mm and a convex repeating unit X = 8 mm. A resin duct of Example 3 having Z / ID = 0.010 was obtained.

<Example 4>
A molded product was obtained through the same steps as in Example 1. By using a pipe making machine with an outer diameter of 79.0 mm, cold air and water are applied from the outside of the pipe making machine to cool the hose-shaped molded product to 100 ° C., and then the hose-shaped molded product is removed from the pipe making machine and air-cooled. The resin duct of Example 4 having an inner diameter of 75.5 mm, a repeating unit of the convex portion X = 8 mm, and Z / ID = 0.023 was obtained.

<Example 5>
A molded product was obtained through the same steps as in Example 1. By stopping the cold air and water from the outside of the pipe making machine, removing the hose-shaped molded product from the pipe making machine at 120 ° C. and air-cooling it, the inner diameter is 50.5 mm, and the repeating unit of the convex portion X = 8 mm, Z. A resin duct of Example 5 having / ID = 0.040 was obtained.

<Example 6>
A molded product was obtained through the same steps as in Example 1. Using a pipe making machine with an outer diameter of 81.9 mm, cool the hose-shaped molded product to 90 ° C by applying cold air and water from the outside of the pipe making machine, and then remove it from the pipe making machine and air-cool it. A resin duct of Example 6 having an inner diameter of 79.0 mm, a repeating unit of the convex portion X = 13 mm, and Z / ID = 0.018 was obtained.

<Example 7>
A molded product was obtained through the same steps as in Example 1. Using a pipe making machine with an outer diameter of 158.0 mm, cool the hose-shaped molded product to 90 ° C by applying cold air and water from the outside of the pipe making machine, and then remove it from the pipe making machine and air-cool it. A resin duct of Example 1 having an inner diameter of 155.0 mm, a convex repeating unit X = 25 mm, and Z / ID = 0.015 was obtained.

<Comparative example 1>
A molded product was obtained through the same steps as in Example 1. At this time, by weakening the twist of the spring-shaped rotating rod of the pipe making machine, the repeating distance of the convex portion was set to 4 mm. The cooling conditions for the hose-shaped molded product were the same as in Example 1. Finally, a resin duct of Comparative Example 1 having an inner diameter of 53.2 mm, a repeating X unit of the convex portion = 4 mm, and Z / ID = 0.011 was obtained.

<Comparative example 2>
A molded product was obtained through the same steps as in Example 1. At this time, by strengthening the twist of the spring-shaped rotating rod of the pipe making machine, the repeating distance of the convex portion was set to 27 mm. The cooling conditions for the hose-shaped molded product were the same as in Example 1. Finally, a resin duct of Comparative Example 2 having an inner diameter of 53.2 mm, a repeating unit of the convex portion X = 27 mm, and Z / ID = 0.013 was obtained.

<Comparative example 3>
A molded product was obtained through the same steps as in Example 1. The hose-shaped molded product is cooled to 130 ° C. by applying cold air and water from the outside of the pipe making machine, and then removed from the pipe making machine and air-cooled to have an inner diameter of 49.5 mm and a repeating unit of the convex portion X =. A resin duct of Comparative Example 3 having 8 mm and Z / ID = 0.051 was obtained.

<Comparative example 4>
A molded product was obtained through the same steps as in Example 1. The hose-shaped molded product is cooled to 50 ° C by applying cold air and water from the outside of the pipe making machine, and then removed from the pipe making machine and air-cooled to have an inner diameter of 53.9 mm and a repeating unit of the convex portion X =. A resin duct of Comparative Example 2 having 8 mm and Z / ID = 0.006 was obtained.

As shown in Examples 1 to 7, when the repeating unit X and Z / ID of the apex of the convex portion on the inner surface of the duct are within the range of the present invention, the obtained resin duct has excellent pressure loss characteristics.
On the other hand, when the repeating unit X of the convex apex of the inner surface of the duct is less than 5 mm as in Comparative Example 1, when X exceeds 20 mm as in Comparative Example 2, Z / ID is 0.05 as in Comparative Example 3. If the Z / ID is less than 0.01 as in Comparative Example 4, the pressure loss characteristics are inferior.

Since the resin duct of the present invention has a specific uneven shape on the inner surface, it has excellent fluid pressure loss characteristics. Furthermore, it is highly flexible and has good workability, so it can be used for ventilation and air conditioning ducts in houses.

As described above, a preferred embodiment of the present invention has been described, but various additions, changes or deletions can be made without departing from the spirit of the present invention, and such additions, changes or deletions are also included in the scope of the present invention. Is done.

Claims (3)

A resin duct composed of a meat portion made of a strip containing at least a non-woven fabric and a spiral core material made of a thermoplastic hard resin, and satisfying the following structures (1) and (2).
(1) When the repeating unit of the apex of the convex portion on the inner surface of the duct is X (mm), 5 mm ≦ X ≦ 25 mm.
(2) When the depth of the depression between the protrusions on the inner surface of the duct is Z (mm) and the inner diameter of the duct is ID (mm), 0.01 ≦ Z / ID ≦ 0.05. Resin ducts of claim 1, the thermoplastic hard resin is characterized that it is an olefin thermoplastic resin. A resin duct in which a heat insulating layer is further coated on the outside of the resin duct according to claim 1 or 2.