Drug injection tube

Abstract

To provide a chemical injection tube with high pressure resistance. [Solution] This technology provides a chemical injection pipe for injecting chemicals into the ground, which is made of a resin composition containing polyethylene resin having a melt flow rate (MFR) of 0.35 g / 10 min or less, as measured in accordance with JIS K7210. The maximum allowable stress of the chemical injection pipe according to this technology can be 4.5 MPa or more. The chemical injected using the chemical injection pipe according to this technology can be a urethane-based injection material.

Description

Technical Field

[0001] The present technology relates to a chemical solution injection tube. More specifically, it relates to a chemical solution injection tube for injecting a chemical solution into the ground.

Background Art

[0002] Technologies for injecting necessary chemical solutions into the ground are being developed for the purpose of strengthening soft ground, crushed ground, filled ground, etc., and ground improvement before construction of tunnels, bridges, roads, etc.

[0003] For example, in Patent Document 1, there is provided a ground improvement injection device that is inserted into a curved insertion hole in the ground and discharges an injection material, which includes a tube body made of a soft resin or rubber, has a discharge hole formed at the tip, and has a supply port for an injection material made of a foaming resin provided at the hand-held end. A flexible injection tube, a packer provided in the middle of the injection tube, and a supply tube that extends along the injection tube on the hand-held side of the packer and supplies an expansion material made of a foaming resin to the packer are provided. By this, even if the insertion hole in the ground is curved, the injection tube can be inserted into the ground, and a technology for reliably injecting the injection material into the ground has been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in the above-mentioned Patent Document 1, in the injection of a chemical solution into the ground, while flexibility of the chemical solution injection tube is required, in reality, pressure resistance capable of withstanding the supply pressure of the chemical solution is also required at the same time.

[0006] Therefore, the main object of the present technology is to provide a chemical solution injection tube having high pressure resistance. [Means for solving the problem]

[0007] The inventors of this invention conducted intensive research on raw materials for chemical injection pipes that would have pressure resistance equivalent to or better than that of nylon pipes, which have been widely used for chemical injection pipes in the past. As a result, they discovered that when polyethylene resin is used as a raw material, differences in its MFR (Metal Fluid Ratio) affect the pressure resistance of the chemical injection pipe, leading to the completion of this technology. In other words, this technology involves a chemical injection pipe for injecting chemicals into the ground, The present invention provides a chemical injection tube made of a resin composition containing polyethylene resin having a melt flow rate (MFR) of 0.35 g / 10 min or less, as measured in accordance with JIS K7210. The maximum allowable stress of the chemical injection pipe related to this technology can be set to 4.5 MPa or higher. The tensile yield stress of the polyethylene resin used in the chemical injection pipe related to this technology, as measured in accordance with JIS K7161, may be 20 MPa or higher. The polyethylene resin used in the chemical injection tube related to this technology may be uncrosslinked polyethylene. The polyethylene resin used in the chemical injection pipe related to this technology may have a minimum required strength (MRS) of 8.0 MPa or higher, as measured in accordance with JIS K6797. The chemical solution injected using the chemical solution injection tube relating to this technology may be a urethane-based injection material. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram illustrating a first embodiment of the chemical injection tube 1 related to this technology. [Figure 2] This is a schematic diagram illustrating a second embodiment of the chemical injection tube 1 related to this technology. [Modes for carrying out the invention]

[0009] The following describes preferred embodiments for implementing this technology. The embodiments described below are examples of typical embodiments of this technology, and any combination of these embodiments is possible. Furthermore, this does not mean that the scope of this technology will be narrowed.

[0010] (1) Raw materials The chemical injection pipe according to this technology is made of a resin composition containing polyethylene resin. Polyethylene resin is inexpensive and lightweight compared to nylon, which has been widely used as a raw material for chemical injection pipes in the past, making it very suitable as a raw material for resin pipes used for chemical injection into the ground. In addition, as long as the function and effect of this technology are not impaired, the chemical injection pipe can be manufactured by freely combining one or more raw materials commonly used in the manufacture of resin pipes. The components of the resin composition used in this technology will be described in detail below.

[0011] (1-1) Polyethylene resin The polyethylene resin used in this technology is characterized by having a melt flow rate (MFR) of 0.35 g / 10 min or less, as measured in accordance with JIS K7210. While the effects and benefits of this technology can be achieved with an upper limit of MFR of 0.35 g / 10 min or less for the polyethylene resin, it is preferably 0.33 g / 10 min or less, more preferably 0.30 g / 10 min or less, and even more preferably 0.25 g / 10 min or less. By using polyethylene resin with an upper limit of MFR within this range, molding stability can be further improved, and the pressure resistance of the manufactured chemical injection pipes can be further enhanced.

[0012] The lower limit of the MFR of the polyethylene resin that can be used in this technology is not particularly limited, but is, for example, 0.01 g / 10 min or more, preferably 0.03 g / 10 min or more, and more preferably 0.05 g / 10 min or more. By using polyethylene resin with an MFR in this range, the flexibility of the manufactured chemical injection tube can be further improved.

[0013] The tensile yield stress of the polyethylene resin used in this technology is not particularly limited as long as it does not impair the operation or effect of this technology. However, the lower limit of the tensile yield stress measured in accordance with JIS K7161 is, for example, 20 MPa or more, preferably 22 MPa or more, and more preferably 23 MPa or more. By using polyethylene resin with a lower limit of tensile yield stress in this range, the pressure resistance of the manufactured chemical injection pipes can be further improved.

[0014] The upper limit of the tensile yield stress of the polyethylene resin that can be used in this technology is not particularly limited, but is, for example, 40 MPa or less, preferably 35 MPa or less, and more preferably 30 MPa or less. By using polyethylene resin with an upper limit of tensile yield stress within this range, the flexibility of the chemical injection pipes manufactured can be improved.

[0015] The polyethylene resin used in this technology may be either crosslinked or uncrosslinked polyethylene, but in this technology, uncrosslinked polyethylene is preferred. Using uncrosslinked polyethylene improves the flexibility of the chemical injection tubes produced.

[0016] The minimum required strength of the polyethylene resin used in this technology is not particularly limited as long as it does not impair the function or effect of this technology. However, the lower limit of the minimum required strength (MRS) measured in accordance with JIS K6797 is, for example, 6.0 MPa or higher, preferably 6.3 MPa or higher, and more preferably 8.0 MPa or higher. By using polyethylene resin with a minimum required strength in this range, the pressure resistance of the manufactured chemical injection pipes can be further improved.

[0017] There is no particular upper limit to the minimum required strength of the polyethylene resin that can be used in this technology; for example, it may be 12.0 MPa or less.

[0018] Examples of the polyethylene resin that can be used in the present technology include ethylene homopolymers such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and very-low-density polyethylene (VLDPE); ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene-butene block copolymers, ethylene-butene random copolymers, ethylene-vinyl acetate copolymers (EVA), and ethylene-methyl methacrylate copolymers. In the present technology, among these, it is preferable to use high-density polyethylene (HDPE). By using high-density polyethylene (HDPE), the pressure resistance of the chemical liquid injection tube to be manufactured can be further improved.

[0019] The polyethylene resin that can be used in the present technology can be produced using a Ziegler-Natta catalyst composed of titanium chloride and an organoaluminum compound, a metallocene catalyst composed of an organometallic complex, a Phillips catalyst composed of a chromium compound such as chromium oxide, etc. However, in the present technology, it is preferable to use a catalyst other than the metallocene catalyst.

[0020] (1-2) Other resin components In the chemical liquid injection tube according to the present technology, resins other than the polyethylene resin with an MFR of 0.35 g / 10 min or less can be used in combination as long as the functions and effects of the present technology are not impaired. For example, thermoplastic resins such as polyolefin resins, polystyrene resins, polyamide resins, and polyester resins other than the polyethylene resin with an MFR of 0.35 g / 10 min or less; thermoplastic elastomers such as olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers can be mentioned.

[0021] (1-3) Other components In the manufacture of the chemical liquid injection tube according to the present technology, as long as the objectives and effects of the present technology are not impaired, as other components, various components that can be used in the manufacture of the resin tube can be freely selected and used singly or in combination of two or more according to the purpose.

[0022] Examples of components that can be used in the manufacture of chemical injection tubes related to this technology include inorganic fillers, flame retardants, stabilizers, plasticizers, colorants, antioxidants, dispersants, ultraviolet absorbers, reinforcing fibers (glass fibers, carbon fibers, etc.), antistatic agents, lubricants, nucleating agents, and the like.

[0023] (2) Manufacturing method The chemical injection tubes related to this technology are characterized by their physical properties and the resin components used, and their manufacturing method is not particularly limited as long as it does not impair the function or effect of this technology. Chemical injection tubes can be manufactured by freely combining one or more general resin tube manufacturing methods.

[0024] In this technology, extrusion molding is preferred. Specifically, for example, a resin raw material and, if necessary, other additives can be supplied to an extruder, heated and mixed to prepare a molten resin composition, which can then be introduced into an annular die located downstream of the extruder and extruded from the tip of the annular die to manufacture a chemical injection pipe.

[0025] (3) Physical properties of the chemical injection tube [Maximum allowable stress] The chemical injection tube according to this technology is characterized by its high pressure resistance. The specific maximum allowable stress of the chemical injection tube according to this technology can be freely set according to the type and viscosity of the chemical to be injected, but the lower limit of the maximum allowable stress of the chemical injection tube according to this technology is, for example, 4.5 MPa or more, preferably 4.6 MPa or more, and more preferably 4.7 MPa or more.

[0026] The upper limit of the maximum allowable stress of the chemical injection pipe in this technology is, for example, 8.0 MPa or less, preferably 7.5 MPa or less, and more preferably 7.0 MPa or less. By setting the upper limit of the maximum allowable stress of the chemical injection pipe within this range, the flexibility of the chemical injection pipe can be improved.

[0027] In this technology, the maximum allowable stress of the chemical injection pipe is the value calculated using the method described in the example below.

[0028] [Destructive pressure] The burst pressure of the chemical injection tube in this technology can be freely set according to the type and viscosity of the chemical intended for injection, but the lower limit of the burst pressure of the chemical injection tube in this technology is, for example, 4.0 MPa or higher, preferably 4.3 MPa or higher, and more preferably 4.5 MPa or higher.

[0029] The upper limit of the burst pressure of the chemical injection tube according to this technology is, for example, 8.0 MPa or less, preferably 7.5 MPa or less, and more preferably 7.0 MPa or less. By setting the upper limit of the burst pressure of the chemical injection tube within this range, the flexibility of the chemical injection tube can be improved.

[0030] In this technology, the burst pressure of the chemical injection tube is the value measured by the method described in the example below.

[0031] [Inner diameter] The inner diameter of the chemical injection tube related to this technology can be freely set according to the condition of the ground to be injected, the type and viscosity of the chemical solution to be injected, etc., as long as it does not impair the function and effect of this technology. The lower limit of the inner diameter of the chemical injection tube is, for example, 5 mm or more, preferably 7 mm or more, more preferably 8 mm or more, and even more preferably 10 mm or more. By setting the lower limit of the inner diameter of the chemical injection tube within this range, moldability can be improved.

[0032] The upper limit of the inner diameter of the chemical injection tube is, for example, 20 mm or less, preferably 17 mm or less, and more preferably 15 mm or less. By setting the inner diameter of the chemical injection tube within this range, the tube can be given an appropriate thickness, thereby improving its pressure resistance.

[0033] [Outer diameter] The outer diameter of the chemical injection pipe related to this technology can be freely set according to the ground conditions, the type and viscosity of the chemical solution to be injected, etc., as long as it does not impair the function and effect of this technology. The lower limit of the outer diameter of the chemical injection pipe related to this technology is, for example, 10 mm or more, preferably 13 mm or more, and more preferably 15 mm or more. By setting the lower limit of the outer diameter of the chemical injection pipe related to this technology to this range, the chemical injection pipe can be given an appropriate thickness, and its pressure resistance can be improved.

[0034] The upper limit of the outer diameter of the chemical injection tube is, for example, 30 mm or less, preferably 25 mm or less, and more preferably 20 mm or less. By setting the outer diameter of the chemical injection tube within this range, moldability can be improved.

[0035] [thickness] The thickness of the chemical injection tube in this technology can be freely set as long as it does not impair the function or effect of this technology. In this technology, the lower limit of the thickness of the chemical injection tube is, for example, 1.0 mm or more, preferably 1.5 mm or more, and more preferably 2.0 mm or more. By setting the lower limit of the thickness of the chemical injection tube within this range, the pressure resistance can be improved.

[0036] The upper limit of the thickness of the chemical injection tube is, for example, 6.0 mm or less, preferably 5.0 mm or less, and more preferably 4.0 mm or less. By setting the thickness of the chemical injection tube within this range, moldability and flexibility can be improved.

[0037] (4) Chemical solution The chemical injection pipe relating to this technology can be used to inject any type of chemical into the ground, as long as it does not impair the action or effect of this technology. Examples include urethane-based injection materials, acrylic-based injection materials, cement-based injection materials, water glass-based injection materials, silica-based injection materials, etc. Among these, the chemical injection pipe relating to this technology is particularly suitable for injecting urethane-based injection materials.

[0038] As a urethane-based injection material, for example, an injection material consisting of a first component containing a polyol and a second component containing an isocyanate can be used. The polyols, isocyanates, and other additives that can be used in the urethane-based injection material can be freely selected according to the ground conditions and the purpose of ground improvement.

[0039] (5) Forms of use of the drug injection tube Figure 1 is a schematic diagram illustrating a first embodiment of the chemical injection pipe 1 according to this technology. The chemical injection pipe 1 according to this technology is inserted into the ground at one end, and the chemical is injected from the chemical supply port 11 at the other end. The direction of insertion of the chemical injection pipe 1 into the ground is indicated by the symbol G in Figure 1. The shape of the chemical injection pipe 1 according to this technology is not particularly limited as long as it is tubular, and can be freely designed according to the condition of the ground, the type and viscosity of the chemical to be injected, etc., as long as the operation and effect of this technology are not impaired.

[0040] The end of the chemical injection pipe 1 in the insertion direction G into the ground (the opposite end of the chemical supply port 11) may be provided with a chemical discharge port 12 for discharging the chemical into the ground. Additionally, one or more chemical discharge holes 121 for discharging the chemical into the ground may be provided on the side wall of the chemical injection pipe 1. Both the chemical discharge port 12 at the end of the chemical injection pipe 1 and the chemical discharge holes 121 on the side wall of the chemical injection pipe 1 may be provided, or only one of them may be provided. Furthermore, depending on the intended location for chemical injection, it is possible to use the chemical injection pipe 1 with unnecessary portions of the chemical discharge port 12 at the end of the chemical injection pipe 1 and the chemical discharge holes 121 on the side wall of the chemical injection pipe 1 blocked off.

[0041] The chemical injection pipe 1 according to this technology may be equipped with a stirring section M for stirring the chemical solution. For example, when injecting a chemical solution consisting of two or more liquids, such as a urethane-based injection material, into the ground, it is preferable to equip the chemical injection pipe 1 with a stirring section M. By equipping the chemical injection pipe 1 with a stirring section M, the liquids will not be completely mixed upstream of the stirring section M, which will slow down the start of the reaction of each liquid and, as a result, reduce the temperature rise. Also, since the reaction will not proceed easily upstream of the stirring section M, the length of the chemical injection pipe 1 can be changed depending on the position of the stirring section M. The specific form of the stirring section M can be freely selected and used as long as it does not impair the operation and effect of this technology. Examples of stirring mechanisms that can be used in this technology include static mixers.

[0042] The chemical injection pipe 1 related to this technology may, as long as it does not impair the purpose or effect of this technology, be equipped with one or more other components that can be used in general resin pipes inserted into the ground, depending on the purpose. Other components that can be used in this technology include, for example, fittings and valves for connecting to various devices used for injecting chemicals into the ground.

[0043] The chemical injection pipe 1 in this technology can be used as a single pipe, as in the first embodiment, but it can also be used as a set of multiple chemical injection pipes 1a, 1b, 1c, and 1d, as in the second embodiment shown in Figure 2. When using multiple chemical injection pipes 1a, 1b, 1c, and 1d, the injection location can be freely set by using chemical injection pipes 1a, 1b, 1c, and 1d of different lengths. Although not shown, it is also possible to branch each chemical injection pipe 1a, 1b, 1c, and 1d in a desired direction to inject the chemical at various locations in the ground. Furthermore, the chemical injected into each chemical injection pipe 1a, 1b, 1c, and 1d may be the same, but it is also possible to inject different chemicals depending on the purpose. [Examples]

[0044] The present technology will be described in more detail below based on the following examples. The examples described below are representative examples of the present technology and should not be interpreted as narrowing the scope of the present technology.

[0045] (1) Manufacturing of chemical injection tubes The resins and their additives shown in Table 1 below are supplied to an extruder, heated and kneaded, then introduced into an annular die located downstream of the extruder. The mixture is then extruded from the lip at the tip of the annular die to produce a product with an outer diameter of 1.6 cm, an inner diameter of 1.3 cm, a thickness of 0.15 cm, and a volume of 68.3 cm³. 3 A chemical injection tube with a diameter of / m was manufactured. The physical properties of the resin used were measured using the following method.

[0046] [density] The density of the resin used was measured in accordance with JIS K7112.

[0047] [MFR] The MFR values ​​of the resins used in Examples 1, 2, and 4, and Comparative Examples 1 to 3, were measured in accordance with JIS K7210. The MFR of the resin used in Example 3 was measured in accordance with ISO 1133. The MFR of the resin used in Comparative Example 4 was measured in accordance with GB / T3682.1. Note that JIS K7210 uses MFR at a load of 21.2N ≈ 2.16kg, while ISO 1133 and GB / T 3682.1 use MFR at a load of 5.0kg.

[0048] [Tensile yield stress] The tensile yield stress of the resins used in Examples 1, 2, and 4, and Comparative Examples 1 to 3, was measured in accordance with JIS K7161. The tensile yield stress of the resin used in Example 3 was measured in accordance with ISO 527. The tensile yield stress of the resin used in Comparative Example 4 was measured in accordance with GB / T1040.

[0049] [Tensile elongation] The tensile elongation of the resins used in Examples 1, 2, and 4, and Comparative Examples 1 to 3, was measured in accordance with JIS K7161. The tensile elongation of the resin used in Example 3 was measured in accordance with ISO 527. The tensile elongation of the resin used in Comparative Example 4 was measured according to GB / T1040.

[0050] [Flexural modulus] The flexural modulus of the resins used in Examples 1, 2, and 4 was measured in accordance with JIS K7171. The flexural modulus of the resin used in Example 3 was measured in accordance with ASTM D790.

[0051] [Charpy impact strength] The Charpy impact strength of the resin used was measured in accordance with JIS K7111.

[0052] [Type D Durometer Hardness] The Type D durometer hardness of the resins used in Examples 1, 2, 4, and Comparative Example 1 was measured in accordance with JIS K7215. The Type D durometer hardness of the resin used in Comparative Example 4 was measured according to GB / T2411.

[0053] (2) Measurement of the physical properties of the chemical injection tube [Gel fraction] The gel fraction of the manufactured drug injection tubes was measured in accordance with JIS K6769:2004.

[0054] [Maximum allowable stress] The maximum allowable stress of the manufactured chemical injection pipe was calculated using the following formula (Naday's formula). Maximum allowable stress (MPa) = (2 × tensile yield stress of resin (MPa) × pipe thickness (cm)) / (pipe outer diameter (cm) - pipe thickness (cm))

[0055] [Destructive pressure] The burst pressure of the manufactured chemical injection tube was measured using the following method. Test equipment: Constant temperature bath (PH-4KT, manufactured by ESPEC Corporation), fittings (manufactured by CATEX Corporation) Measuring equipment: Test pump (Kyowa Corporation "TP-50"), pressure gauge (maximum pressure 6.0 MPa) Test conditions: A 250 mm sample was cut from the manufactured chemical injection tube. The cut sample was placed in a constant temperature bath set to 23°C, and a pressure of 2.0 MPa was applied to the inside of the cut sample with room temperature water. After standing for 2 minutes, the sample was checked for leaks and other defects. Subsequently, the pressure was gradually increased, and the maximum pressure at which the sample ruptured was measured.

[0056] (3) Results The results are shown in Table 1 below.

[0057] [Table 1]

[0058] (4) Discussion Examples 1-4, which used polyethylene resin with an MFR of 0.35 g / 10 min or less as the raw material, showed higher maximum allowable stress and fracture pressure compared to Comparative Examples 1-4, which used polyethylene resin with an MFR exceeding 0.35 g / 10 min as the raw material. Furthermore, the fracture pressure of Examples 1-4 was equivalent to or higher than that of tubes made from nylon, which has been commonly used as a raw material for chemical injection tubes.

Claims

1. A chemical injection pipe for injecting chemicals into the ground, A chemical injection tube made of a resin composition containing polyethylene resin having a melt flow rate (MFR) of 0.35 g / 10 min or less, as measured in accordance with JIS K7210.

2. A chemical injection tube according to claim 1, wherein the maximum allowable stress is 4.5 MPa or more.

3. The chemical injection tube according to claim 1, wherein the polyethylene resin has a tensile yield stress of 20 MPa or more, as measured in accordance with JIS K7161.

4. The chemical injection tube according to claim 1, wherein the polyethylene resin is non-crosslinked polyethylene.

5. The chemical injection tube according to claim 1, wherein the polyethylene resin has a minimum required strength (MRS) of 8.0 MPa or more, as measured in accordance with JIS K6797.

6. The chemical solution injection tube according to claim 1, wherein the chemical solution is a urethane-based injection material.

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