A pouring method for the preparation of large-volume plastic scintillator

Abstract

The present invention discloses a pouring method for preparing large-volume plastic scintillator. It includes the following steps: subjecting industrial-grade styrene to alkali washing, water washing and vacuum distillation to obtain styrene monomer; 2) in a mixer, mixing the styrene monomer with a first scintillator, a second scintillator and an initiator to obtain a mixture, and after the first scintillator and the second scintillator are dissolved, adding the mixture into a prepolymerization kettle for prepolymerization reaction to obtain a precast slurry; 3) pouring the precast slurry into a tempered glass mold through a heating conduit, sealing it and placing it in a water bath for polymerization reaction, and then placing it in a high-temperature chamber to continue the polymerization reaction, thus obtaining the plastic scintillator. In addition to ensuring that the scintillator has good luminescence performance (the light yield can reach 82% of EJ-200), the present invention also has the characteristics of low energy consumption, high efficiency and suitability for large-scale production; moreover, the production cost is significantly reduced, and plastic scintillators of any size can be obtained.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear detection materials and relates to a pouring method for preparing large-volume plastic scintillators. Background Art

[0002] Nuclear radiation detection technology is an important tool for people to understand and recognize the microscopic world, and is the foundation and important part of the nuclear technology field. Nuclear radiation detection plays a crucial role in both basic research including particle physics, nuclear physics, space radiation environment measurement, and practical applications including nuclear medicine, radiation protection, industrial fields, etc. Classified by nuclear detection materials, nuclear radiation detectors mainly include three categories: gas detectors, scintillator detectors, and semiconductor detectors. Among them, plastic scintillator, as a kind of organic scintillator, can be used for detecting various radiations such as α, β, γ, cosmic rays, etc., and has the advantages of easy processing, non-deliquescence, radiation resistance, short scintillation decay time, etc., and is a widely used scintillator. Summary of the Invention

[0003] The purpose of the present invention is to provide a pouring method for preparing large-volume plastic scintillators.

[0004] The method for preparing large-volume plastic scintillators using the pouring process of the present invention not only ensures that the scintillator has good luminescence performance (the light yield can reach 82% of EJ-200), but also has the characteristics of low energy consumption, high efficiency, and suitability for large-scale production. In addition, on the one hand, the large-volume plastic scintillator provided by this method significantly reduces the production cost through large-scale production, and on the other hand, it itself is a highly transparent amorphous thermoplastic material. The above two advantages can meet the needs of users for batch procurement and arbitrary processing.

[0005] The present invention provides a pouring method for preparing large-volume plastic scintillators, including the following steps: subjecting industrial-grade styrene to alkali washing, water washing, and vacuum distillation to obtain styrene monomer;

[0006] 2) In a mixer, mixing the styrene monomer with a first scintillator, a second scintillator, and an initiator to obtain a mixture, and after the first scintillator and the second scintillator are dissolved, adding the mixture to a prepolymerization kettle for prepolymerization reaction to obtain a precast slurry;

[0007] 3) Pouring the precast slurry into a tempered glass mold through a heating conduit, sealing it, and placing it in a water bath for polymerization reaction, and then placing it in a high-temperature chamber to continue the polymerization reaction to obtain a plastic scintillator.

[0008] In the above preparation method, the industrial-grade styrene is subjected to the alkali washing using an aqueous sodium hydroxide solution with a mass percentage of 10% - 15% of equal mass;

[0009] The conditions for the vacuum distillation are as follows: the negative pressure in the rotary evaporation kettle is maintained at 180 - 240 mmHg, the water bath temperature is increased to 95 - 105 °C, and at the same time, the stirrer is turned on to keep its rotation speed at 80 - 100 rpm.

[0010] In the above preparation method, the mass ratio of the styrene monomer, the first scintillator, the second scintillator and the initiator can be 100:0.8 - 1.2:0.015 - 0.025:0.08 - 0.12, specifically 100:1:0.02:0.1, 100:0.8 - 1:0.015 - 0.020:0.08 - 0.12, 100:1.0 - 1.2:0.020 - 0.025:0.08 - 0.10 or 100:0.9 - 1.1:0.017 - 0.024:0.09 - 0.11;

[0011] A magnetic stirring device is provided in the mixer;

[0012] To prevent the mixture from being oxidized during the polymerization process, the prepolymerization reaction is carried out in an inert atmosphere; the inert atmosphere is nitrogen or argon;

[0013] The prepolymerization kettle is internally provided with a stirring device, and the rotation speed of the stirring device can be 30 - 40 rpm, specifically 35 rpm;

[0014] The working temperature of the prepolymerization kettle can be 100 °C - 125 °C, the time of the prepolymerization reaction can be 3.5 - 4.5 h, specifically 4 h, so that the conversion rate of the mixture can be 30% - 35%.

[0015] In the above preparation method, the heating temperature of the heating conduit is 90 - 100 °C;

[0016] The temperature of the water bath can be 80 - 90 °C;

[0017] The time for the polymerization reaction in the water bath can be 12 - 14 h, specifically 12 h or 12 - 13 h;

[0018] The temperature for the polymerization reaction in the high-temperature chamber can be 100 - 120 °C, and the time can be 1.5 h - 2.5 h, specifically 2 h, 2 h - 2.5 h, 1.5 h - 2 h or 1.75 h - 2.25 h.

[0019] In the above preparation method, the tempered glass mold is made according to the following steps: two pieces of tempered glass are used, and a silicone rubber sleeve with a thickness of 10 mm - 30 mm is clamped around the two pieces, and a precast slurry pouring inlet is reserved on one side;

[0020] The tempered glass mold is fastened with a clamp during use;

[0021] In step 3), the air inside the tempered glass mold is removed before sealing the mold.

[0022] In the above preparation method, after the prefabricated slurry is poured into the tempered glass mold and sealed in step 3), the operation is as follows: the tempered glass mold is sent to the shelf through a conveyor belt, and the shelf sends the mold into a water bath. When more than 95% of the polymerization reaction is completed, the shelf exits the water bath; after the tempered glass mold is unloaded, it is sent into the high-temperature chamber.

[0023] In the above preparation method, after the polymerization reaction is carried out in the high-temperature chamber in step 3), it further includes: cooling the temperature of the tempered glass mold to 50-60 °C, taking the tempered glass mold, and completing demolding to obtain the plastic scintillator.

[0024] In the above preparation method, the size of the plastic scintillator is 2m 2 ~8m 2 。

[0025] The present invention has the following beneficial effects:

[0026] 1. Using industrial-grade styrene as the matrix of the organic scintillator can reduce the raw material procurement cost.

[0027] 2. Adopting a water bath, on the one hand, water is easily obtained, and on the other hand, the water bath can keep the glass mold evenly heated. There is no secondary pollution of oil stains on the glass mold, which is convenient for quick cleaning and reuse.

[0028] 3. The scintillator prepared by the present invention has good luminescence performance (the light yield can reach 82% of EJ-200), and by controlling the size of the tempered glass mold, plastic scintillators of any size can be obtained.

[0029] 4. The pouring process for preparing large-volume plastic scintillators in the present invention has the characteristics of low energy consumption, high efficiency, and suitability for large-scale production due to the supply guarantee of its raw materials, convenient operation, and high production efficiency. It is beneficial to reduce the cost of organic scintillators and further provides the possibility for low-cost batch procurement of plastic scintillators. Description of the Drawings

[0030] Figure 1 It is a comparison diagram of the signal response waveforms of the styrene plastic scintillator prepared in Example 1 of the present invention and EJ-200.

[0031] Figure 2 It is a comparison of the measurement results of the plastic scintillator prepared in Example 1 of the present invention and EJ-200 for cosmic ray muons.

[0032] Figure 3 It is a process flow chart of the pouring process of the plastic scintillator prepared in Example 1 of the present invention.

[0033] Figure 4 This is the structural schematic diagram of the tempered glass mold in Embodiment 1 of the present invention.

[0034] Figure 5 This is the cross-sectional structural schematic diagram of the silicone rubber sleeve clamped between two pieces of tempered glass in the tempered glass mold in Embodiment 1 of the present invention.

[0035] Figure 4-5 The various markings in it are as follows:

[0036] 1 Tempered glass, 2 Silicone rubber sleeve, 3 Hose. Specific implementation manner

[0037] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods.

[0038] Unless otherwise specified, the materials, reagents, etc. used in the following embodiments can all be obtained from commercial channels.

[0039] Embodiment 1:

[0040] According to the pouring method for preparing large-volume plastic scintillator as Figure 3 shown, prepare large-volume plastic scintillator:

[0041] Step 1: Wash industrial-grade styrene with a 10% - 15% (specifically 10% in one experiment) sodium hydroxide aqueous solution by mass, wash with water, dry and purify, and then perform vacuum distillation on styrene to remove polymerization inhibitors such as tert-butylcatechol to obtain pure styrene monomer;

[0042] Step 2: Add the obtained pure styrene monomer to a mixer with a stirring device, weigh 1% of 2,5-diphenyloxazole, 0.02% of 2,5-diphenyl-1,3,4-oxadiazole, and 0.1% of azobisisobutyronitrile according to the mass of the pure styrene monomer, mix with the styrene monomer and put in a clean magnetic stirrer. Under the action of magnetic force, stir at a rate of 1060 rpm for more than 1 hour to dissolve 2,5-diphenyloxazole, 0.02% of 2,5-diphenyl-1,3,4-oxadiazole, and 0.1% of azobisisobutyronitrile in the styrene monomer, and then take out the magnetic stirrer;

[0043] Step 3: Open the conduit valve on the lower side of the stirrer to make the mixed liquid enter the prepolymerization kettle. Open the nitrogen filling valve to remove the air in the prepolymerization kettle. Set the temperature of the prepolymerization kettle in the range of 100°C - 125°C (specifically 110°C), and start the rotor in the prepolymerization kettle to stir the mixed liquid, and keep the stirring speed at 35 rpm. The prepolymerization time is about 4 hours, so that the conversion rate of the mixed liquid is between 30% - 35% (specifically 32% in one experiment). At this time, the preformed slurry is in a viscous state similar to glycerol;

[0044] Step 4: Prepare the tempered glass mold. Figure 4-5 As shown, two clean, flat, and size-required tempered glasses 1 are used, a silicone rubber sleeve 2 (thickness is 10 mm to 30 mm, specifically 20 mm) with required thickness is clamped around the two tempered glasses 1, the glass mold is fastened with a clamp, and an inlet for prefabricated slurry is reserved on one side of the tempered glass mold, and the inlet can be specifically provided with a hose 3 for introducing prepolymer;

[0045] Step 5: Open the valve at the bottom of the prepolymerization kettle to allow the prefabricated slurry to flow continuously into the tempered glass mold along the heating conduit (i.e., hose 3) at the bottom of the prepolymerization kettle. After canning, seal the mold to minimize air retention in the mold.

[0046] Step 6: The tempered glass mold is sent to the shelf by a conveyor belt, and the shelf is sent into a water bath at 80-90°C (specifically 85°C) for polymerization reaction under the traction of a hook. The water bath polymerization time is about 12 hours;

[0047] Step 7: After the pre-pulping conversion rate exceeds 95%, the rack is dragged out of the water bath under the traction of the hook, and the rack is sent to a high temperature chamber with a temperature of 100 to 120° C. (specifically 100° C.) for further polymerization reaction for 2 hours;

[0048] Step 8: Cool down the temperature of the high temperature chamber to 50-60℃ (specifically 50℃). When the mold temperature is consistent with the ambient temperature of the high temperature chamber, remove the mold fixture and glass, demould and obtain 2m 2 ~8m 2 Large size plastic flash (a specific experiment obtained a size of 6m 2 ).

[0049] The large volume plastic flash prepared by the above method was tested and its fluorescence response time characteristics were comparable to those of the common EJ-200 plastic flash on the market (see Figure 1 ), the light output is about 86% of EJ-200 (see Figure 2 ), but the present invention can prepare plastic flash of any size, and under the above-mentioned optimized method conditions, it is easier to obtain large-sized plastic flash.

Claims

1. A casting method for the preparation of large-volume plastic scintillator, comprising the following steps: 1) Alkaline washing, water washing and vacuum distillation are carried out on industrial-grade styrene to obtain styrene monomer; 2) In a mixer, the styrene monomer is mixed with a first scintillator, a second scintillator and an initiator to obtain a mixture. After the first scintillator and the second scintillator are dissolved, the mixture is added to a prepolymerization kettle for prepolymerization reaction to obtain a precast slurry; The mass ratio of the styrene monomer to the first scintillator, the second scintillator and the initiator is 100: 0.8~1.2: 0.015~0.025: 0.08~0.12; The working temperature of the prepolymerization kettle is 100°C~125°C, and the time of the prepolymerization reaction is 3.5~4.5h, so that the conversion rate of the mixture is 30%~35%; 3) The precast slurry is poured into a tempered glass mold through a heating conduit, sealed and placed in a water bath for polymerization reaction, and then placed in a high-temperature chamber for continuous polymerization reaction to obtain the plastic scintillator; The temperature of the water bath is 80~90°C; the time for the polymerization reaction in the water bath is 12~14h; The temperature for the polymerization reaction in the high-temperature chamber is 100~120°C; the time for the polymerization reaction in the high-temperature chamber is 1.5~2.5h.

2. The pouring method according to claim 1, characterized in that: The industrial-grade styrene is subjected to the alkaline washing with an equal mass of an aqueous sodium hydroxide solution with a mass percentage of 10%~15%; The conditions for the vacuum distillation are as follows: a negative pressure state of 180~240mmHg is maintained in the rotary evaporation kettle, the water bath temperature is increased to 95~105°C, and at the same time, a stirrer is started, and its rotation speed is maintained at 80~100rpm.

3. The pouring method according to claim 1 or 2, characterized in that: A magnetic stirring device is provided in the mixer; The prepolymerization reaction is carried out in an inert atmosphere; the inert atmosphere is nitrogen or argon; The prepolymerization kettle is internally provided with a stirring device, and the rotation speed of the stirring device is 30~40rpm.

4. The pouring method according to claim 1 or 2, characterized in that: The heating temperature of the heating conduit is 90~100°C.

5. The pouring method according to claim 1 or 2, characterized in that: The tempered glass mold is made according to the following steps: Two pieces of tempered glass are used, and a silicone rubber sleeve with a thickness of 10mm~30mm is clamped around the two pieces of tempered glass, and an inlet for pouring the precast slurry is reserved on one side; The tempered glass mold is fastened with a clamp during use; In step 3), the air in the tempered glass mold is exhausted before sealing the tempered glass mold.

6. The pouring method according to claim 1 or 2, characterized in that: In step 3), after the precast slurry is poured into the tempered glass mold and sealed, the operation is as follows: The tempered glass mold is sent to a shelf through a conveyor belt, and the shelf sends the mold into a water bath pool for water bath. When more than 95% of the polymerization reaction is completed, the shelf exits the water bath pool; after the tempered glass mold is unloaded, it is sent into the high-temperature chamber.

7. The pouring method according to claim 1 or 2, characterized in that: After the polymerization reaction in the high-temperature chamber in step 3), it further includes: cooling the temperature of the tempered glass mold to 50~60°C, taking the tempered glass mold, completing demolding, and obtaining the plastic scintillator.

8. The pouring method according to claim 1 or 2, characterized in that: The size of the plastic scintillator is 2 m 2 ~8 m 2 .

Images