Microduct-use resin tube

Abstract

Provided is a microduct-use resin tube that is excellent with respect to the insertion and laying of an optical fiber cable.　A microduct-use resin tube 1 into which an optical fiber cable is inserted and laid has as at least an inside surface 10 that is formed from a polyethylene resin containing a nonreactive silicone at 0.01 to 20 mass%.

Description

Resin pipe for microducts

[0001] The present invention relates to a resin pipe for a microduct into which an optical fiber cable is inserted and laid.

[0002] The so-called microduct system method, in which an optical fiber cable is inserted and installed in a small-diameter microduct disposed within a large-diameter main duct, has been widely adopted in Europe and the United States because once the conduit (microduct) is installed, it is possible to add, change, or update the optical fiber cable without large-scale construction work. Generally, the microduct system method employs a method of inserting the optical fiber cable into the microduct by pressurizing it with high-pressure compressed air, or a method that combines air-pressurized pushing and solid-state pushing (see, for example, Patent Document 1).

[0003] In either method, the tube that constitutes the microduct is required to have low friction, be resistant to cable buckling, and have good air pumping characteristics. Conventionally, pipes and tubes for air-pressurized optical cables have been made of synthetic resins such as polyethylene (see, for example, Patent Documents 2 and 3). Patent Document 2 proposes a pipe for air-pressurized optical cables that consists of a pipe body made of synthetic resin and a spiral wire that is half-embedded in the inner wall surface of the pipe body. Patent Document 3 also proposes a pipe for air-pressurized optical cables that has a Vicat softening point of 120 to 140°C, a density of 0.950 to 0.970 g / cm. ３ , Olsen stiffness 7500 to 13000 kg / cm ２ Plastic pipes made of polyethylene have been proposed.

[0004] JP 2001-309519, JP 5-323128, JP 10-62665

[0005] In recent years, the distances over which optical fiber cables are inserted and installed have become longer, and so there is a demand for resin pipes for microducts that have lower friction and are easier to push in by air pressure or solid state. However, the conventional resin pipes mentioned above have poor sliding properties with the cable, making them unsuitable for long-distance installation.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a resin pipe for a microduct that is excellent in the ability to insert and install an optical fiber cable.

[0007] The resin pipe for a microduct according to the present invention is a resin pipe for a microduct into which an optical fiber cable fiber is inserted and laid, and at least the inner surface is formed of a polyethylene resin containing 0.01 to 20% by mass of a non-reactive silicone. The polyethylene resin may contain two or more types of polyethylene with different densities. In this case, the polyethylene resin may contain, for example, high-density polyethylene (HDPE) and low-density polyethylene (LDPE). The non-reactive silicone may be, for example, silicone gum, silicone rubber, silicone oil, or silicone powder. The resin pipe for a microduct according to the present invention may be composed of two layers, an inner layer and an outer layer, and the inner layer may be formed of a polyethylene resin containing 0.01 to 20% by mass of a non-reactive silicone, and the outer layer may be formed of a polyethylene resin that does not contain a non-reactive silicone. Alternatively, the resin pipe for a microduct of the present invention may have an inner layer, an intermediate layer, and an outer layer, wherein the inner layer is formed of a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone, the intermediate layer is formed of a polyethylene resin that does not contain non-reactive silicone, and the outer layer is formed of a polyethylene resin that contains 0.01 to 20% by mass of non-reactive silicone or a polyethylene resin that does not contain non-reactive silicone.

[0008] According to the present invention, the friction of the inner surface that comes into contact with the optical fiber cable can be reduced, thereby improving the performance of inserting and laying the optical fiber cable.

[0009] 1A and 1B are cross-sectional views showing examples of the structure of a resin pipe according to an embodiment of the present invention.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] The resin pipe according to an embodiment of the present invention is a resin pipe for a microduct into which an optical fiber cable is inserted and laid, and at least the inner surface is formed of a polyethylene resin containing 0.01 to 20 mass% of non-reactive silicone. The "inner surface" here refers to the hollow surface that comes into contact with the optical fiber cable. The optical fiber cable may be inserted by air pressure pushing, solid pushing, or a combination of these.

[0012] 1 and 2A and 2B are cross-sectional views showing structural examples of resin pipes according to embodiments of the present invention. The resin pipes according to the present embodiments may have a single-layer structure composed of only a single resin layer 11, such as resin pipe 1 shown in Fig. 1; a two-layer structure composed of an inner layer 21 and an outer layer 22, such as resin pipe 2 shown in Fig. 2A; or a three-layer structure having an inner layer 31, an outer layer 32, and an intermediate layer 33, such as resin pipe 3 shown in Fig. 2B. The intermediate layer 33 shown in Fig. 2B may be composed of multiple layers, and may include a layer formed of a resin or material other than polyethylene.

[0013] In the case of the single-layer resin pipe 1 shown in Figure 1, the entire resin layer 11 is formed from a polyethylene resin containing 0.01 to 20 mass% of non-reactive silicone. In the case of the two-layer resin pipe 2 shown in Figure 2A, both the inner layer 21 and the outer layer 22 may be formed from a polyethylene resin containing 0.01 to 20 mass% of non-reactive silicone. However, from the viewpoint of suppressing increases in manufacturing costs, it is preferable to form the outer layer 22 from a polyethylene resin that does not contain non-reactive silicone. This allows for the inner surface 20 to be provided with slidability while reducing manufacturing costs.

[0014] Furthermore, in the case of the three-layered resin pipe 3 shown in Figure 2B, it is sufficient that at least the inner layer 31 is formed of a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone. The middle layer 33 and outer layer 32 may also be formed of a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone, but from the viewpoint of suppressing increases in manufacturing costs, it is preferable to form the middle layer 33 of a polyethylene resin that does not contain non-reactive silicone. On the other hand, from the viewpoint of suppressing increases in manufacturing costs, it is preferable to form the outer layer 32 of a polyethylene resin that does not contain non-reactive silicone, but by forming it of a polyethylene resin that contains 0.01 to 20% by mass of non-reactive silicone, it is possible to impart slidability to the outer surface as well.

[0015] The sizes of the resin pipes 1, 2, and 3 can be appropriately selected depending on the specifications of the microduct, but may be, for example, an outer diameter of 4 to 40 mm, an inner diameter of 2 to 38 mm, and a thickness of 1 to 3 mm. In the case of the two-layer resin pipe 2 shown in FIG. 2A, the thickness of the inner layer 21 is preferably 1 to 50% of the total thickness (total thickness of the inner layer 21 and the outer layer 22), and more preferably 5 to 30%. In the case of the three-layer resin pipe 3 shown in FIG. 2B, the thicknesses of the inner layer 31 and the outer layer 32 are each preferably 1 to 45% of the total thickness (total thickness of the inner layer 31, the outer layer 32, and the intermediate layer 33), and more preferably 5 to 30%.

[0016] The lengths of the resin pipes 1, 2, and 3 are not particularly limited and can be appropriately selected depending on the specifications of the microduct, production facilities, etc. The inner and / or outer surfaces of the resin pipes 1, 2, and 3 may be subjected to surface treatment such as unevenness or spiraling.

[0017] [Non-reactive silicone] In the resin pipes 1, 2, and 3 of this embodiment, the polyethylene resin constituting the inner surfaces 10, 20, and 30 contains non-reactive silicone in the range of 0.01 to 20% by mass. If the non-reactive silicone content is less than 0.01% by mass, the effect of improving the slidability of the inner surfaces 10, 20, and 30 cannot be obtained. Furthermore, even if the non-reactive silicone content exceeds 20% by mass, further improvement in slidability cannot be expected, resulting in increased manufacturing costs and reduced moldability (shapeability). From the perspective of balancing the slidability of the inner surfaces 10, 20, and 30 and manufacturing costs, the amount of non-reactive silicone in the polyethylene resin is preferably 0.05 to 10% by mass.

[0018] The non-reactive silicone used in the resin pipes 1, 2, and 3 of this embodiment may be any silicone that does not have a reactive functional group, and examples thereof include non-reactive silicone gum, silicone rubber, silicone oil, and silicone powder.

[0019] [Polyethylene Resin] The polyethylene resin constituting the inner surfaces 10, 20, and 30 of the resin pipes 1, 2, and 3 is not particularly limited as long as it is a resin primarily composed of polyethylene, but from the viewpoint of improving sliding properties, an HDPE resin primarily composed of high-density polyethylene (HDPE) is preferred. Furthermore, in the case of the single-layer resin pipe 1 shown in FIG. 1, from the viewpoint of ease of insertion of an optical fiber cable, the flexural modulus of the polyethylene resin is preferably 600 to 1800 MPa when the primary component is high-density polyethylene (HDPE), 100 to 400 MPa when the primary component is low-density polyethylene (LDPE), and 150 to 600 MPa when the primary component is linear low-density polyethylene (LLDPE).

[0020] On the other hand, from the viewpoint of improving the dispersibility of the non-reactive silicone and imparting flexibility, it is preferable to form the inner surfaces 10, 20, 30 from a polyethylene resin containing two or more types of polyethylene with different densities. When the polyethylene resin contains two types of polyethylene, for example, ３ and polyethylene having a density of 0.91 to 0.93 g / cm ３ The polyethylene may be used.

[0021] It is more preferable that the polyethylene resin constituting the inner surfaces 10, 20, 30 contains high-density polyethylene (HDPE), low-density polyethylene (LDPE), and / or linear low-density polyethylene (LLDPE). In this case, the content of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) in the polyethylene resin can be appropriately selected depending on the amount of non-reactive silicone blended and the physical properties required of the resin pipes 1, 2, 3, such as flexibility, but can be, for example, 0.01 to 20% by mass.

[0022] In the case of the two-layered resin pipe 2 shown in Fig. 2A, the polyethylene resin forming the inner layer 21 may be the same as or different from the polyethylene resin forming the outer layer 22. In the case of the three-layered resin pipe 3 shown in Fig. 2B, the polyethylene resin forming the inner layer 31, the polyethylene resin forming the outer layer 32, and the polyethylene resin forming the intermediate layer 33 may be the same as or different from each other.

[0023] The resin pipes 1, 2, and 3 of this embodiment may be colored by adding pigments or dyes to the polyethylene resin described above. Weathering agents, heat resistance agents, and the like may also be added to the polyethylene resin. Furthermore, other additives may be added to the polyethylene resin as needed, as long as they do not impair the effects of the present invention. Examples of other additives that may be added to the polyethylene resin include processing heat stabilizers, light stabilizers, UV absorbers, antioxidants, lubricants, colorants, antistatic agents, flame retardants, water repellents, waterproofing agents, hydrophilic agents, electrical conductivity agents, thermal conductivity agents, electromagnetic wave shielding agents, translucency adjusters, fluorescent agents, sliding agents, transparency agents, antiblocking agents, metal deactivators, and antibacterial agents.

[0024] As described above in detail, the resin pipe of this embodiment has at least the inner surface formed of polyethylene resin containing 0.01 to 20 mass % of non-reactive silicone, thereby reducing friction on the surface that comes into contact with the optical fiber cable and improving sliding properties. As a result, a microduct that is excellent in optical fiber cable insertion and installation performance and allows for long-distance installation can be realized.

[0025] EXAMPLES The effects of the present invention will be specifically described below with reference to Examples and Comparative Examples. In these Examples, resin pipes were produced by the following method, and their shaping properties and sliding properties were evaluated.

[0026] <Preparation of Evaluation Samples> (1) Raw Materials Polyethylene resin A: high-density polyethylene Polyethylene resin B: low-density polyethylene Non-reactive silicone: silicone gum

[0027] (2) Method for Producing Resin Pipes The raw materials described above were blended and kneaded in the proportions shown in Table 1 below, and the resulting mixture was molded using an extruder equipped with a pipe die to obtain resin pipes of the Examples and Comparative Examples. The molding conditions were a rotation speed of 26.7 rpm, pipe die nozzle dimensions of 18 mm outer diameter and 12 mm inner diameter, and molding speed of 3 m / min. The dimensions of the resin pipes were 12 mm outer diameter, 8 mm inner diameter, and 2 mm wall thickness.

[0028] <Evaluation> (1) Shapeability The shapeability of the resin pipes of the Examples and Comparative Examples was evaluated based on the roundness calculated from the flattening ratio. Specifically, for each resin pipe prepared by the above-mentioned method, the maximum and minimum values ​​of the outer diameter at any position were measured with a vernier caliper, and the flattening ratio was calculated by the arithmetic mean. As a result, pipes with a flattening ratio of 10% or less were evaluated as acceptable (○), and pipes with a flattening ratio of more than 10% were evaluated as unacceptable (×).

[0029] (2) Sliding property The kneaded material was placed in a mold of 150 mm x 150 mm x 2 mm, and a load of 10 MPa was applied for 3 minutes using a hot press at 220 ° C. to form a sheet. The sheet was cut into a width of 63 mm to obtain an evaluation test piece (length 150 mm, thickness 2 mm). Then, in accordance with the method specified in JIS K7125, the dynamic friction coefficient of the surface of each test piece was measured. For the measurement, a friction coefficient measuring device was used, which included a table movable in a direction parallel to the installation surface, a reinforcing plate for fixing the test piece to the table, a mating material placed on the test piece, a weight for pressing the mating material against the test piece with a constant load, and a load cell connected to the mating material.

[0030] The mating material was the same polyethylene resin A as used for the test piece, the dimensions of the contact surface of the mating material with the test piece were 63 mm x 63 mm, the weight of the weight (load during measurement) was 50 g, and the table movement speed was 100 mm / min. As a result, those whose dynamic friction coefficient was 0.2 or less were rated as pass (○), and those whose dynamic friction coefficient was more than 0.2 were rated as fail (×).

[0031] (3) Overall Evaluation A sample that was evaluated as acceptable (○) for both the shapeability and the sliding property was evaluated as passed (○), and a sample that was evaluated as unacceptable (×) for even one of the items was evaluated as unacceptable (×). The results are shown in Table 1 below.

[0032]

[0033] As shown in Table 1 above, Comparative Example 1, which was formed from a polyethylene resin containing no non-reactive silicone, had poor sliding properties. Furthermore, Comparative Example 2, which used a polyethylene resin containing more than 20% by mass of non-reactive silicone, had poor formability. In contrast, Examples 1 to 4, in which the inner surface was formed from a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone, had good formability and sliding properties.

[0034] From the above results, it was confirmed that the present invention can realize a resin pipe for a microduct that has excellent performance for inserting and laying optical fiber cables.

[0035] 1 to 3: Resin pipe 10, 20, 30: Inner surface 11: Resin layer 21, 31: Inner layer 22, 32: Outer layer 33: Intermediate layer

Claims

1. A resin pipe for a microduct into which an optical fiber cable is inserted and laid, at least the inner surface of which is made of polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone.

2. The resin pipe for microducts according to claim 1, wherein the polyethylene resin contains two or more types of polyethylene with different densities.

3. A resin pipe for a microduct according to claim 1 or 2, wherein the polyethylene resin contains high density polyethylene (HDPE) and low density polyethylene (LDPE).

4. A resin pipe for a microduct according to any one of claims 1 to 3, wherein the non-reactive silicone is silicone gum, silicone rubber, silicone oil or silicone powder.

5. A resin pipe for microducts according to any one of claims 1 to 4, which is composed of two layers, an inner layer and an outer layer, the inner layer being formed of a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone, and the outer layer being formed of a polyethylene resin that does not contain non-reactive silicone.

6. A resin pipe for microducts according to any one of claims 1 to 4, having an inner layer, an intermediate layer and an outer layer, wherein the inner layer is formed of a polyethylene resin containing 0.01 to 20% by mass of non-reactive silicone, the intermediate layer is formed of a polyethylene resin that does not contain non-reactive silicone, and the outer layer is formed of a polyethylene resin that contains 0.01 to 20% by mass of non-reactive silicone or a polyethylene resin that does not contain non-reactive silicone.

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