Paste-like composition and method for producing a paste-like composition

Abstract

The present invention provides a paste-like composition that can adhere to lead blocks, does not generate harmful fumes when heated, and can supply appropriate amounts of Bi and Sn to the appropriate locations on the lead block. [Solution] A paste-like composition used for cutting lead blocks or hard lead blocks, comprising an alloy powder of Bi and Sn with an average particle size of 0.020 mm or less, an aqueous phosphoric acid solution, a volatile oil, and a surfactant.

Description

Technical Field

[0001] This invention relates to a paste-like composition or the like that softens a lead block (or a hard lead block; the same applies hereinafter) as a low-melting-point alloy in order to cut the lead block.

Background Art

[0002] Conventionally, as one of the decommissioning operations of nuclear power plants, there is a cutting operation of lead blocks that were used as radiation shielding materials.

[0003] As a method for cutting lead blocks, Patent Document 1 discloses melting an alloy material composed of Bi and Sn (melting point: 139°C) in a container and dropping it onto the lead block from a hole at the bottom of the container, thereby softening the lead block as a low-melting-point alloy composed of Bi, Pb, and Sn, applying a blade to the softened portion, and moving the blade downward while sliding it to cut the lead block.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method disclosed in Patent Document 1, since the alloy material composed of Bi and Sn is dropped from the hole at the bottom of the container, it is difficult to control the amount and position of the alloy material supplied onto the lead block, and the alloy material is wasted by being dropped onto parts other than the cutting part or by being dropped in an amount more than necessary.

[0006] Furthermore, because the alloy material was dripped from above, the lead block could only be cut from the top surface, which was inconvenient. Therefore, when we attempted to cut the lead block using a commercially available paste containing an alloy material made of Bi and Sn that could be adhered to surfaces other than the top surface, we found that it produced harmful smoke when heated.

[0007] In view of the above problems, the object of this invention is to provide a paste-like composition that can be adhered to a lead block, does not generate harmful smoke when heated, and can supply an appropriate amount of Bi and Sn to an appropriate location on the lead block, and a method for producing the paste-like composition. [Means for solving the problem]

[0008] To solve the above objective, claim 1 is a paste-like composition used for cutting lead blocks or hard lead blocks, characterized by comprising an alloy powder of Bi and Sn having an average particle size of 0.020 mm or less, an aqueous phosphoric acid solution, a volatile oil, and a surfactant.

[0009] Claim 2 is the paste-like composition according to Claim 1, characterized in that the volatile oil is at least one of turpentine oil (pine essential oil), spike lavender oil (aspic oil), and petrol.

[0010] Claim 3 is a paste-like composition according to Claim 1, further comprising a drying oil.

[0011] Claim 4 is a paste-like composition according to Claim 3, characterized in that the drying oil has an iodine value of 100 to 130.

[0012] Claim 5 is a paste-like composition according to any one of claims 1 to 4, wherein the surfactant further comprises at least one of sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

[0013] Claim 6 is a paste-like composition according to any one of claims 1 to 4, characterized in that the volume ratio of the phosphoric acid aqueous solution to the volatile oil is 100:1 to 10:1.

[0014] Claim 7 is a method for producing a paste-like composition used for cutting lead blocks or hard lead blocks, comprising: a first production step of adding a surfactant and a volatile oil to an aqueous phosphoric acid solution and stirring to produce an additive; and a second production step of adding the additive to an alloy powder of Bi and Sn having an average particle size of 0.020 mm or less and stirring to produce a paste-like composition.

[0015] Claim 8 is a method for producing the paste-like composition described in Claim 7, characterized in that the volatile oil is at least one of turpentine oil (pine essential oil), spike lavender oil (aspic oil), and petrol.

[0016] Claim 9 is a method for producing the paste-like composition described in Claim 7, characterized in that in the first production step, a drying oil is further added to the aqueous phosphoric acid solution.

[0017] Claim 10 is a method for producing the paste-like composition described in Claim 9, characterized in that the drying oil has an iodine value of 100 to 130.

[0018] Claim 11 is a method for producing a paste-like composition according to any one of claims 7 to 10, characterized in that the surfactant further comprises at least one of sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

[0019] Claim 12 is a method for producing a paste-like composition according to any one of claims 7 to 10, characterized in that the volume ratio of the phosphoric acid aqueous solution to the volatile oil is 100:1 to 10:1. [Effects of the Invention]

[0020] According to this invention, it is possible to adhere to a lead block, generate no harmful smoke when heated, and supply an appropriate amount of Bi and Sn to an appropriate position of the lead block.

Brief Description of the Drawings

[0021] [Figure 1] It is a perspective view showing a state in which the lead block is being heated in the present embodiment. [Figure 2] It is a flowchart showing an example of a method for cutting a lead block in the present embodiment. [Figure 3] It is a flowchart showing an example of a method for generating a paste-like composition in the present embodiment. [Figure 4] It is a component table of an example of a Bi-Sn alloy paste in the present example.

Modes for Carrying Out the Invention

[0022] Embodiments of this invention will be described.

[0023] The paste-like composition of the present embodiment contains Bi and Sn and is used for cutting a lead block. In the present embodiment, the object to be cut is described as a lead block, but the paste-like composition of the present invention can also be used for cutting a hard lead block containing about 10% antimony.

[0024] Since the paste-like composition is in a paste state, it can be adhered to the side surface or the bottom surface of the lead block, and by heating in a state of being adhered to the lead block, the lead block is softened as a low-melting-point alloy composed of Bi, Pb, and Sn. As a method for heating the paste-like composition, there are a method of adhering the paste-like composition to a lead block in a pre-heated state, a method of adhering it to a lead block at about room temperature and then heating the lead block and / or the paste-like composition, and the like.

[0025] Next, referring to FIGS. 1 and 2, an outline of a method for cutting the lead block 1 using the paste-like composition P will be described.

[0026] The method for cutting lead block 1 broadly includes a supply process (step S1), a heating process (step S2), and a cutting process (step S3).

[0027] In the supply process (step S1), the paste-like composition P is filled into a syringe (not shown) and extruded from the tip of the syringe to supply it to the portion of the lead block 1 to be cut. At this time, the paste-like composition P may be supplied while adhering it to the lead block 1.

[0028] In the heating step (step S2), the paste-like composition P adhered to the lead block 1 is heated to approximately 180°C using a heat gun 2. At this time, the paste-like composition P may be heated directly with the heat gun 2, or the paste-like composition P may be heated indirectly by heating the lead block 1. This causes the portion of the lead block 1 to which the paste-like composition P is adhered to soften into a low-melting-point alloy composed of Bi, Pb, and Sn. Instead of the heat gun 2, an infrared heater or heating wire may be used as the heating means. Furthermore, when using an infrared heater, black paint may be applied to the object to be heated. For example, by applying black paint to the lead block 1 and irradiating the applied portion with infrared rays, the lead block 1 can be heated efficiently.

[0029] Note that the melting points of the composition [Bi:58wt%, Sn:42wt%] are 139°C, the melting point of the composition [Bi:45wt%, Sn:55wt%] is 165°C, and the melting point of the composition [Bi:65wt%, Sn:35wt%] is 165°C. Therefore, heating to about 180°C in step S2 is sufficient, but depending on the components of the composition, heating to about 165°C may suffice.

[0030] In the cutting process (step S3), the lead block 1 is cut by applying the tip of the cutting tool to the softened portion of the lead block 1 and moving the tool downwards (when cutting the lead block 1 from the top surface to the bottom surface). A reciprocating saw or an ultrasonic cutter may be used as the cutting tool.

[0031] Furthermore, depending on the size of the lead block 1, steps S1 to S3 are repeated to cut the lead block 1. At this time, steps S1 to S3 may be performed simultaneously. That is, the paste-like composition P may be supplied to the part to be cut, the part may be heated, and the cutting tool may be moved. Alternatively, as described above, steps S1 and S2 may be swapped, the lead block 1 (even just the part to be cut) may be heated in advance, the paste-like composition P may be supplied to it, and the paste-like composition P may be heated.

[0032] Next, the paste-like composition P will be described.

[0033] The paste-like composition P is produced by adding additives containing an aqueous phosphoric acid solution, a volatile oil, and a surfactant to an alloy powder of Bi and Sn.

[0034] The mass ratio of Bi to Sn in the alloy powder should be 45:55 to 65:35. Furthermore, to form the alloy powder into a paste, an alloy powder with an average particle size of 0.020 mm (20 μm) or less should be used. For example, a commercially available Bi-Sn alloy with a particle size of 3 to 11 μm and an average particle size of 7 μm (58 wt% Bi, 42 wt% Sn) can be used as the alloy powder.

[0035] When Bi-Sn alloy is heated, it oxidizes and becomes covered with an oxide film, preventing it from liquefying. Therefore, it does not react with lead block 1, and oxidation during heating must be prevented. In this embodiment, a phosphoric acid aqueous solution is included as an additive to prevent oxidation of the Bi-Sn alloy during heating. The concentration of the phosphoric acid aqueous solution is preferably 10 wt% to 20 wt%.

[0036] When Bi-Sn alloys are made into a paste, uniform water distribution within the alloy powder ensures that a uniform alloy is formed upon heating. To achieve this, a volatile oil is added as an additive. At least one of the following volatile oils can be used: turpentine oil (pine oil), spike lavender oil (aspic oil), and petrol. The volume ratio of the phosphoric acid aqueous solution to the volatile oil is preferably 100:1 to 10:1.

[0037] Furthermore, a surfactant is included as an additive to emulsify the volatile oil. The surfactant is selected based on the HLB value of the surfactant, depending on the volatile oil included as an additive. As a surfactant, at least one of sorbitan monolaurate (HLB value 8.6) and polyoxyethylene sorbitan monooleate (HLB value 10) can be used. Span® 20 can be used as the sorbitan monolaurate. Tween® 80 can be used as the polyoxyethylene sorbitan monooleate. However, including both Span 20 (sorbitan monolaurate) (HLB value 8.6) and Tween 80 (polyoxyethylene sorbitan monooleate) (HLB value 10) makes it easier to emulsify the drying oil described later. The volume ratio of the phosphoric acid aqueous solution to the surfactant is preferably 1000:1 to 100:1.

[0038] When adding additives to Bi-Sn alloy powder, the preferred ratio of alloy powder to additive is 1.0 mL to 2.0 mL of additive per 10 g of alloy powder.

[0039] Furthermore, when a paste-like composition P produced using an additive that employs only turpentine oil as the volatile oil is adhered to a lead block at room temperature and then heated, the turpentine oil evaporates during the heating process, making it impossible to soften the lead block 1. Therefore, a drying oil that does not evaporate easily during heating may be further included in the additive. The volume ratio of the phosphoric acid aqueous solution to the drying oil is preferably 100:1 to 10:1. In addition, the addition of a drying oil facilitates emulsification of the phosphoric acid aqueous solution, surfactant, and volatile oil.

[0040] Drying oils are classified based on their iodine value, an indicator of the abundance of C=C double bonds in their composition. These include drying oils with an iodine value of 130 or higher (e.g., linseed oil, tung oil, poppy seed oil, perilla oil, walnut oil, sesame oil, safflower oil, sunflower oil, etc.), semi-drying oils with an iodine value of 100 to 130 (e.g., sesame oil, corn oil, cottonseed oil, soybean oil, etc.), and non-drying oils with an iodine value of 100 or less (e.g., olive oil, tonsil oil, peanut oil, coconut oil, camellia oil, rapeseed oil). Additives may include at least one of these drying, semi-drying, or non-drying oils.

[0041] Next, the method for producing the paste-like composition P of this embodiment will be explained using Figure 3.

[0042] First, the surfactant is added to the phosphoric acid aqueous solution and stirred (Step S11). As mentioned above, at least one of Span20 (sorbitan monolaurate) and Tween80 (polyoxyethylene sorbitan monooleate) can be selected as the surfactant. The volume ratio of the phosphoric acid aqueous solution to the surfactant should be 1000:1 to 100:1.

[0043] Next, a volatile oil is added to the mixture prepared in step S11 and stirred (step S12). As mentioned above, at least one of the following can be selected as the volatile oil: turpentine oil (pine essential oil), spike lavender oil (aspic oil), and petrol. The volume ratio of the phosphoric acid aqueous solution to the volatile oil should be 100:1 to 10:1.

[0044] Next, at least one of a drying oil, semi-drying oil, or non-drying oil is added to the mixture obtained in step S12 and stirred to obtain an additive (step S13). However, if no drying oil, semi-drying oil, or non-drying oil is added as an additive, step S13 is skipped. As mentioned above, examples of drying oils include linseed oil, tung oil, poppy seed oil, perilla oil, walnut oil, sesame oil, safflower oil, and sunflower oil. Examples of semi-drying oils include sesame oil, corn oil, cottonseed oil, and soybean oil. Examples of non-drying oils include olive oil, tonsil oil, peanut oil, coconut oil, camellia oil, and rapeseed oil. The volume ratio of the phosphoric acid aqueous solution to the drying oil should be 100:1 to 10:1.

[0045] Next, the additive prepared in step S13 is added to the Bi-Sn alloy powder and stirred to obtain a paste-like composition P (step S14). As mentioned above, the ratio of alloy powder to additive when adding the additive to the Bi-Sn alloy powder is 1.0 mL to 2.0 mL of additive per 10 g of alloy powder.

[0046] Steps S11-S13 (excluding step S13 if no drying oil, semi-drying oil, or non-drying oil is added as an additive) are an example of the "first production step" of the present invention. Step S14 is an example of the "second production step" of the present invention.

[0047] As described above, the paste-like composition P of this embodiment can be supplied in an appropriate amount to the appropriate location on the lead block 1. Compared to the conventional method of dropping an alloy material consisting of Bi and Sn onto the lead block 1, the amount of Bi-Sn alloy used is reduced by 92%, and the cutting time is shortened by 56% due to the reduction in time loss.

[0048] Next, examples of the present invention will be described. In this example, a method for producing a Bi-Sn alloy paste, which is an example of a paste-like composition P, will be described. Figure 4 shows an example of chemicals used to produce the Bi-Sn alloy paste.

[0049] First, as an example of step S11, 50 mL of 19% wt% phosphoric acid aqueous solution is mixed with 50 μL of 2 wt% Tween 80 aqueous solution, and then 50 μL of 2 wt% Span 20 aqueous solution is added and mixed.

[0050] Next, as an example of step S12, 0.5 mL of turpentine oil is added to the mixture obtained in the example of step S11 and stirred.

[0051] Next, as an example of step S13, 0.5 mL of at least one of drying oils, semi-drying oils, or non-drying oils is added to the mixture obtained in the example of step S12 and stirred to obtain an additive. If multiple types of oils are selected from drying oils, semi-drying oils, and non-drying oils, the total amount added should be 0.5 mL.

[0052] Next, as an example of step S14, 0.5 mL of the additive obtained in the example of step S13 is added to 3.5 g of Bi-Sn alloy powder (Bi-Sn powder with a particle size of 3-11 μm and an average particle size of 7 μm (58 wt% Bi, 42 wt% Sn)) and stirred to obtain a Bi-Sn alloy paste.

[0053] Furthermore, experiments were conducted on Bi-Sn alloy pastes prepared by adding drying oils (linseed oil), semi-drying oils (sesame oil), and non-drying oils (olive oil) as additives. The results showed that the Bi-Sn alloy paste using semi-drying oil (sesame oil) as an additive formed the Bi-Sn alloy the fastest upon heating, compared to the Bi-Sn alloy pastes using drying oils (linseed oil) and non-drying oils (olive oil) as additives. Therefore, among drying, semi-drying, and non-drying oils, it is preferable to include a semi-drying oil (iodine value of 100 to 130) as an additive. [Explanation of Symbols]

[0054] 1: Lead block 2: Heat gun P: Paste-like composition

Claims

1. A paste-like composition used for cutting lead blocks or hard lead blocks, Bi and Sn alloy powder with an average particle size of 0.020 mm or less, Aqueous solution of phosphoric acid and Volatile oils and Surfactants and A paste-like composition characterized by containing the following:

2. A paste-like composition according to claim 1, The paste-like composition is characterized in that the volatile oil is at least one of turpentine oil (pine essential oil), spike lavender oil (aspic oil), and petrol.

3. A paste-like composition according to claim 1, A paste-like composition characterized by further containing a drying oil.

4. A paste-like composition according to claim 3, The drying oil is a paste-like composition characterized by having an iodine value of 100 to 130.

5. A paste-like composition according to any one of claims 1 to 4, The surfactant is characterized by further comprising at least one of sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

6. A paste-like composition according to any one of claims 1 to 4, A paste-like composition characterized in that the volume ratio of the aqueous phosphoric acid solution to the volatile oil is 100:1 to 10:

1.

7. A method for producing a paste-like composition used for cutting lead blocks or hard lead blocks, A first production step involves adding a surfactant and a volatile oil to an aqueous phosphoric acid solution and stirring to produce an additive, A second production step involves adding the additive to an alloy powder of Bi and Sn having an average particle size of 0.020 mm or less, stirring, and producing a paste-like composition. A method for producing a paste-like composition characterized by containing the following:

8. A method for producing the paste-like composition described in claim 7, A method for producing a paste-like composition, characterized in that the volatile oil is at least one of turpentine oil (pine essential oil), spike lavender oil (aspic oil), and petrol.

9. A method for producing the paste-like composition described in claim 7, A method for producing a paste-like composition, characterized in that the first production step involves further adding a drying oil to the aqueous phosphoric acid solution.

10. A method for producing the paste-like composition described in claim 9, The method for producing a paste-like composition is characterized in that the drying oil has an iodine value of 100 to 130.

11. A method for producing a paste-like composition according to any one of claims 7 to 10, A method for producing a paste-like composition, characterized in that the surfactant further comprises at least one of sorbitan monolaurate and polyoxyethylene sorbitan monooleate.

12. A method for producing a paste-like composition according to any one of claims 7 to 10, A method for producing a paste-like composition, characterized in that the volume ratio of the aqueous phosphoric acid solution to the volatile oil is 100:1 to 10:1.

Images