Low-retraction-rate plastic alloy material, preparation method and sounding pipe

Abstract

The invention relates to the technical field of plastic alloy, in particular to a low-retraction-rate plastic alloy material, a preparation method and a sounding pipe. The low-retraction-rate plastic alloy material is prepared from the following raw materials in parts by mass: 50 to 100 parts of polyvinyl chloride, 20 to 40 parts of polycarbonate, 5 to 15 parts of tetraethoxysilane, 1 to 2 parts of carboxyl-terminated polyamidoamine, 0.01 to 0.1 part of lanthanum oxide, 1 to 5 parts of a fiber reinforcing agent, 1 to 2 parts of a calcium-zinc stabilizer and 1 to 2 parts of an antioxidant. The problem that polyvinyl chloride is prone to retraction is effectively solved, the impact strength is improved, the problem that nano silicon dioxide is poor in dispersity in a system is solved, the problem of compatibility between nano particles and polymers is solved, and the obtained alloy material has good thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of plastic alloys, and in particular to a low-shrinkage plastic alloy material, a preparation method and an acoustic detection tube. Background Art

[0002] The sonic detection tube is an indispensable sonic detection tube. The quality of a pile can be detected by using the sonic detection tube. When filling, the sonic detection tube is pre-buried in the pile. When testing, the transmitting transducer and the receiving transducer are respectively set in two pipes. By emitting high-frequency signals while rising in one sonic detection tube and then testing in another sonic detection tube, the defect location of concrete, the integrity of filling and other properties can be determined. It plays an important role in construction. Currently, the commonly used materials for sonic detection tubes include metal and plastic. The metal sonic detection tube has the disadvantages of high density and difficulty in construction, which limits its use.

[0003] Plastic acoustic detection pipes are corrosion-resistant and can effectively save materials when used in the construction of pipe piles. Plastic acoustic detection pipes are usually made of PVC plastic, but since PVC material is easy to shrink, its bonding performance with concrete is poor. At the same time, since concrete will have a strong squeezing effect on the acoustic detection pipe, the acoustic detection pipe is very easy to be damaged.

[0004] Polycarbonate (PC) has outstanding impact toughness, transparency and dimensional stability, and can be blended with many other resins to form blends. Among the five major engineering plastics, the output of polycarbonate is second only to PA, and its application is rapidly expanding from electronics, electrical, automotive, construction, office machinery, packaging and other departments to aviation, aerospace, electronic computers, optical disks and many other high-tech fields. At present, in order to improve the performance of PVC plastics, compounding it with polycarbonate to prepare a plastic alloy material with low shrinkage, high mechanical strength, good impact strength, and not easy to crack during use has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a low-shrinkage plastic alloy material, a preparation method and an acoustic detection tube.

[0006] A low-shrinkage plastic alloy material comprises the following raw materials by mass: 50-100 parts of polyvinyl chloride, 20-40 parts of polycarbonate, 5-15 parts of tetraethyl orthosilicate, 1-2 parts of carboxyl-terminated polyamidoamine, 0.01-0.1 parts of lanthanum oxide, 1-5 parts of fiber reinforcing agent, 1-2 parts of calcium zinc stabilizer and 1-2 parts of antioxidant.

[0007] Preferably, the weight average molecular weight of polyvinyl chloride is 42,000-46,000.

[0008] Preferably, the weight average molecular weight of the polycarbonate is 50,000-60,000.

[0009] Preferably, the fiber reinforcement is calcium sulfate whiskers.

[0010] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1078, and antioxidant DLTDP.

[0011] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add tetraethyl orthosilicate to an ethanol aqueous solution and ultrasonically treat for 1-2 hours, adjust the pH value of the system to 8-9, add carboxyl-terminated polyamidoamine and continue ultrasonically treating for 1-2 hours, let stand at room temperature for 5-10 hours, filter, wash, dry, and crush to obtain reinforced silica; S2, mixing polyvinyl chloride and reinforced silica, stirring at 180-190° C. for 10-30 min, adding lanthanum oxide and continuing stirring for 10-40 min, cooling to room temperature, adding polycarbonate, fiber reinforcement, calcium zinc stabilizer, and antioxidant and stirring for 1-5 min to obtain a premix; S3, extrude the premix, biaxially stretch at 110-130°C, and cool to room temperature.

[0012] Preferably, in S1, the ultrasonic frequency is 5-10 kHz and the drying temperature is 60-90°C.

[0013] Preferably, in S3, a twin-screw extruder is used for extrusion, the screw speed is 60-150 r / min, and the extrusion temperature is 190-200°C.

[0014] Preferably, in S3, during the biaxial stretching process, the stretching ratio is 1-2.

[0015] The above-mentioned low shrinkage plastic alloy material is used to make the acoustic detection tube. Beneficial Effects

[0016] The present invention can effectively reduce the thermal expansion and contraction of plastics, improve the overall mechanical properties to a certain extent, and has good affinity with concrete, is not easy to produce gaps between concrete, and has a low shrinkage rate, which helps to improve the construction convenience and integrity of the acoustic testing pipe during the acoustic testing process.

[0017] The present invention adds carboxyl-terminated polyamide amine to nano-silicon dioxide and combines them. Since the carboxyl-terminated polyamide amine has a special molecular structure, the bonding strength between the nano-silicon dioxide and the polyamide amine is high, and the polyamide amine can be well compatible with and embedded in polyvinyl chloride resin molecules, which can effectively solve the problem that the polyvinyl chloride material is easy to shrink. When used for the acoustic detection tube, it has excellent stability and good affinity with concrete. At the same time, it can promote full contact between polyvinyl chloride and polycarbonate. The product not only has significantly enhanced impact resistance, but is also not prone to cracking during use. In combination with the effect of lanthanum oxide, the rigidity of the product is effectively improved on the basis of ensuring heat resistance and stability, and the reliability of the acoustic detection tube is enhanced.

[0018] The invention effectively solves the problem of easy shrinkage of polyvinyl chloride, not only improves the impact strength, but also solves the problem of poor dispersibility of nano silicon dioxide in the system, overcomes the problem of compatibility between nano particles and polymers, and the obtained alloy material has good thermal stability. Compared with pure polyvinyl chloride materials, the mechanical properties, thermal stability and aging resistance of the invention are significantly improved.

[0019] The present invention optimizes the material formula production process and combines the biaxial stretching production process, so that the plastic alloy acoustic detection pipe has higher ring stiffness and impact resistance, meets the construction requirements under any conditions, has the characteristics of easy use, light weight, good connection sealing and corrosion resistance, and is an ideal substitute for steel acoustic detection pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a comparison chart of the tensile strength and bending strength of the sheets made from the premixes obtained in Example 5 and Comparative Examples 1-2.

[0021] Figure 2 The figure is a comparison chart of the impact strength of sheets made from the premixes obtained in Example 5 and Comparative Examples 1-2.

[0022] Figure 3 It is a comparison chart of the shrinkage rate and impact strength of the tubular profiles obtained by biaxial stretching in Example 5 and Comparative Examples 1-2.

[0023] Figure 4 This is a comparison chart of the ring stiffness and crush resistance of the tubular profiles obtained by biaxial stretching in Example 5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0024] The present invention will be further explained below in conjunction with specific embodiments.

[0025] The polyvinyl chloride used below was purchased from a certain cultural chemical company in Jiangsu, and its weight average molecular weight was 45,000; the polycarbonate used below was purchased from a certain European Plastic Chemical Company in Ningbo, and its weight average molecular weight was 55,000; the calcium zinc stabilizer used below was purchased from a certain Jisen Composite Materials Company in Kunshan. Example 1

[0026] A low-shrinkage plastic alloy material comprises the following raw materials: 50 kg of polyvinyl chloride, 20 kg of polycarbonate, 5 kg of tetraethyl orthosilicate, 1 kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.01 kg of lanthanum oxide, 1 kg of calcium sulfate whisker, 1 kg of calcium zinc stabilizer and 1 kg of antioxidant 1010.

[0027] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 20 kg of 40% ethanol aqueous solution and ultrasonically treat for 1 hour at an ultrasonic frequency of 5 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 1 hour. Let stand at room temperature for 5 hours, filter, wash, dry at 60°C, and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 180° C. for 10 min, adding lanthanum oxide and continuing stirring for 10 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1010, stirring at a speed of 1000 r / min for 1 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 60 r / min, the extrusion temperature is 190° C., biaxial stretching is performed at a temperature of 110° C., the stretching ratio is 1, and the mixture is cooled to room temperature. Example 2

[0028] A low-shrinkage plastic alloy material comprises the following raw materials: 100kg of polyvinyl chloride, 40kg of polycarbonate, 15kg of tetraethyl orthosilicate, 2kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.1kg of lanthanum oxide, 5kg of calcium sulfate whisker, 2kg of calcium zinc stabilizer and 2kg of antioxidant DLTDP.

[0029] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 40 kg of 60% ethanol aqueous solution and ultrasonically treat for 2 h at an ultrasonic frequency of 10 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 2 h. Let stand at room temperature for 10 h, filter, wash, dry at 90° C., and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 190° C. for 30 min, adding lanthanum oxide and continuing stirring for 40 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant DLTDP, stirring at a speed of 2000 r / min for 5 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 150 r / min, the extrusion temperature is 200° C., biaxial stretching is performed at a temperature of 130° C., the stretching ratio is 2, and the temperature is cooled to room temperature. Example 3

[0030] A low-shrinkage plastic alloy material, whose raw materials include: 70kg of polyvinyl chloride, 35kg of polycarbonate, 8kg of tetraethyl orthosilicate, 1.7kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.02kg of lanthanum oxide, 4kg of calcium sulfate whisker, 1.3kg of calcium zinc stabilizer, and 1.8kg of antioxidant 1010.

[0031] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 25 kg of 55% ethanol aqueous solution and ultrasonically treat for 80 min at an ultrasonic frequency of 8 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 80 min. Let stand at room temperature for 9 h, filter, wash, dry at 70°C, and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 188° C. for 15 min, adding lanthanum oxide and continuing stirring for 30 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1010, stirring at a speed of 1200 r / min for 4 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 80 r / min, the extrusion temperature is 197° C., biaxial stretching is performed at a temperature of 115° C., the stretching ratio is 1.5, and the mixture is cooled to room temperature. Example 4

[0032] A low-shrinkage plastic alloy material, whose raw materials include: 90kg of polyvinyl chloride, 25kg of polycarbonate, 12kg of tetraethyl orthosilicate, 1.3kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.08kg of lanthanum oxide, 2kg of calcium sulfate whisker, 1.7kg of calcium zinc stabilizer, and 1.2kg of antioxidant 1078.

[0033] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 35 kg of 45% ethanol aqueous solution and ultrasonically treat for 100 min at an ultrasonic frequency of 7 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 100 min. Let stand at room temperature for 7 h, filter, wash, dry at 80° C., and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 182° C. for 25 min, adding lanthanum oxide and continuing stirring for 20 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1078, stirring at a speed of 1800 r / min for 2 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 120 r / min, the extrusion temperature is 193° C., biaxial stretching is performed at a temperature of 125° C., the stretching ratio is 1.5, and the mixture is cooled to room temperature. Example 5

[0034] A low-shrinkage plastic alloy material, whose raw materials include: 80kg of polyvinyl chloride, 30kg of polycarbonate, 10kg of tetraethyl orthosilicate, 1.5kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.05kg of lanthanum oxide, 3kg of calcium sulfate whisker, 1.5kg of calcium zinc stabilizer, and 1.5kg of antioxidant 1010.

[0035] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 30 kg of 50% ethanol aqueous solution and ultrasonically treat for 90 min at an ultrasonic frequency of 9 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 90 min. Let stand at room temperature for 8 h, filter, wash, dry at 75° C., and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 185°C for 20 minutes, adding lanthanum oxide and continuing to stir for 25 minutes, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1010, stirring at a speed of 1500r / min for 3 minutes to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 100 r / min, the extrusion temperature is 195° C., biaxial stretching is performed at a temperature of 120° C., the stretching ratio is 1.5, and the mixture is cooled to room temperature.

[0036] Comparative Example 1 A low-shrinkage plastic alloy material, whose raw materials include: 80kg of polyvinyl chloride, 30kg of polycarbonate, 10kg of tetraethyl orthosilicate, 1.5kg of 2.0-generation carboxyl-terminated polyamidoamine, 0.05kg of lanthanum oxide, 3kg of calcium sulfate whisker, 1.5kg of calcium zinc stabilizer, and 1.5kg of antioxidant 1010.

[0037] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 30 kg of 50% ethanol aqueous solution and ultrasonically treat for 90 min at an ultrasonic frequency of 9 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Allow to stand at room temperature for 8 h, filter, wash, dry at 75°C, and crush to obtain nano-silicon dioxide. S2, feeding polyvinyl chloride, nano-silicon dioxide, and 2.0-generation carboxyl-terminated polyamidoamine into a high-speed kneader, stirring at a temperature of 185° C. for 20 min, adding lanthanum oxide and continuing stirring for 25 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1010, and stirring at a speed of 1500 r / min for 3 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 100 r / min, the extrusion temperature is 195° C., biaxial stretching is performed at a temperature of 120° C., the stretching ratio is 1.5, and the mixture is cooled to room temperature.

[0038] Comparative Example 2 A low-shrinkage plastic alloy material, whose raw materials include: 80kg of polyvinyl chloride, 30kg of polycarbonate, 10kg of tetraethyl orthosilicate, 1.5kg of 2.0-generation carboxyl-terminated polyamidoamine, 3kg of calcium sulfate whisker, 1.5kg of calcium zinc stabilizer, and 1.5kg of antioxidant 1010.

[0039] The method for preparing the above-mentioned low shrinkage plastic alloy material comprises the following steps: S1. Add ethyl orthosilicate to 30 kg of 50% ethanol aqueous solution and ultrasonically treat for 90 min at an ultrasonic frequency of 9 kHz. Use ammonia water to adjust the pH value of the system to 8-9. Add 2.0 generation carboxyl-terminated polyamidoamine and continue ultrasonically treating for 90 min. Let stand at room temperature for 8 h, filter, wash, dry at 75° C., and crush to obtain reinforced silica. S2, feeding polyvinyl chloride and reinforced silica into a high-speed kneader, stirring at a temperature of 185° C. for 20 min, cooling to room temperature, adding polycarbonate, calcium sulfate whisker, calcium zinc stabilizer, and antioxidant 1010, stirring at a speed of 1500 r / min for 3 min to obtain a premix; S3. The premix is ​​fed into a twin-screw extruder for extrusion, the screw speed is controlled to be 100 r / min, the extrusion temperature is 195° C., biaxial stretching is performed at a temperature of 120° C., the stretching ratio is 1.5, and the mixture is cooled to room temperature.

[0040] The premixes obtained in Example 5 and Comparative Examples 1-2 were extruded through a twin-screw extruder (screw speed of 100 r / min, extrusion temperature of 195° C.) to form sheets, and then the mechanical properties of each group of sheet samples were tested, as follows: (1) Determine the tensile strength of each group of specimens with reference to GB / T 1040.2-2022 "Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics"; (2) Determine the flexural strength of each group of specimens with reference to GB / T 9341-2008 “Determination of flexural properties of plastics”; (3) The impact strength of each group of samples was determined with reference to GB / T 1843-2008 “Determination of cantilever beam impact strength of plastics”.

[0041] like Figure 1 and Figure 2 As shown, the sheet made from the premix obtained in Example 5 has the highest tensile strength, flexural strength and impact strength, which is better than that of Comparative Examples 1-2 (P < 0.05).

[0042] The following performance tests were conducted on the tubular profiles (outer diameter 50 mm, wall thickness 2.5 mm, L-threaded connection) obtained by biaxial stretching in Example 5 and Comparative Examples 1-2: (1) Refer to GB / T 6671-2001 "Determination of longitudinal shrinkage of thermoplastic plastic pipes" to determine the shrinkage rate of each group of samples.

[0043] (2) The impact strength of each group of samples was determined with reference to GB / T 14152-2001 “Test method for external impact resistance of thermoplastic pipes - Clockwise rotation method”.

[0044] (3) The ring stiffness of each group of specimens was determined with reference to GB / T 9647-2015 “Determination of Ring Stiffness of Thermoplastic Pipes”.

[0045] (4) The flattening resistance of each group of samples was determined with reference to JT / T 871-2013 "High-strength steel-plastic sonic testing tube for concrete cast-in-place piles". The two parallel plates were gradually brought closer together. On the basis that the distance between the two parallel plates was greater than 65% of the outer diameter of the sonic testing tube, the relationship between the distance between the two plates and the outer diameter of the sonic testing tube was determined when cracks appeared on the sonic testing tube.

[0046] like Figure 3 and Figure 4 As shown, the tubular profile obtained in Example 5 has the smallest shrinkage rate, while the impact strength, ring stiffness and crush resistance are the highest, which is better than that of Comparative Examples 1-2 (P < 0.05).

[0047] The applicant believes that the reason for the above results is that the present invention adds carboxyl-terminated polyamide amine to nano-silicon dioxide and combines them. Since the carboxyl-terminated polyamide amine has a special molecular structure, the bonding strength between it and the nano-silicon dioxide is high, and it can be well compatible with and embedded in the polyvinyl chloride resin molecules, which can effectively solve the problem that the polyvinyl chloride material is easy to shrink. When used for the acoustic detection tube, it has excellent stability and good affinity with concrete. At the same time, it can promote full contact between polyvinyl chloride and polycarbonate. The product not only has significantly enhanced impact resistance, but is also not prone to cracking during use. Combined with the effect of lanthanum oxide, the rigidity of the product is effectively improved on the basis of ensuring heat resistance and stability, and the reliability of the acoustic detection tube is enhanced.

[0048] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A low shrinkage plastic alloy material, characterized in that: The raw materials include, by mass, 50-100 parts of polyvinyl chloride, 20-40 parts of polycarbonate, 5-15 parts of tetraethyl orthosilicate, 1-2 parts of carboxyl-terminated polyamidoamine, 0.01-0.1 parts of lanthanum oxide, 1-5 parts of fiber reinforcing agent, 1-2 parts of calcium zinc stabilizer and 1-2 parts of antioxidant.

2. The low shrinkage plastic alloy material according to claim 1, characterized in that: The weight average molecular weight of polyvinyl chloride is 42,000-46,000.

3. The low shrinkage plastic alloy material according to claim 1, characterized in that: The weight average molecular weight of polycarbonate is 50,000-60,000.

4. The low shrinkage plastic alloy material according to claim 1, characterized in that: The fiber reinforcement is calcium sulfate whisker.

5. The low shrinkage plastic alloy material according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 1078, and antioxidant DLTDP.

6. A method for preparing a low shrinkage plastic alloy material as claimed in any one of claims 1 to 5, characterized in that: The steps include: S1. Add tetraethyl orthosilicate to an ethanol aqueous solution and ultrasonically treat for 1-2 hours, adjust the pH value of the system to 8-9, add carboxyl-terminated polyamidoamine and continue ultrasonically treating for 1-2 hours, let stand at room temperature for 5-10 hours, filter, wash, dry, and crush to obtain reinforced silica; S2, mixing polyvinyl chloride and reinforced silica, stirring at 180-190° C. for 10-30 min, adding lanthanum oxide and continuing stirring for 10-40 min, cooling to room temperature, adding polycarbonate, fiber reinforcement, calcium zinc stabilizer, and antioxidant and stirring for 1-5 min to obtain a premix; S3, extrude the premix, biaxially stretch at 110-130°C, and cool to room temperature.

7. The method for preparing the low shrinkage plastic alloy material according to claim 6, characterized in that: In S1, the ultrasonic frequency is 5-10kHz and the drying temperature is 60-90°C.

8. The method for preparing the low shrinkage plastic alloy material according to claim 6, characterized in that: In S3, a twin-screw extruder is used for extrusion, the screw speed is 60-150r / min, and the extrusion temperature is 190-200°C.

9. The method for preparing a low shrinkage plastic alloy material according to claim 6, characterized in that: In S3, during the biaxial stretching process, the stretching ratio is 1-2.

10. A low shrinkage plastic alloy material as claimed in any one of claims 1 to 5 used for making an acoustic detection tube.

Images