An organotin compound-doped plastic scintillator and preparation method thereof

Abstract

The present invention relates to an organotin compound-doped plastic scintillator and a preparation method thereof. The organotin compound-doped plastic scintillator comprises: a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound; the content of the initiator in the organotin compound-doped plastic scintillator is 0 to 1 wt%; the content of the fluorescent dye is 0.01 to 30 wt%; the content of the crosslinking agent is 0 to 10 wt%; and the content of the organotin compound is 0.1 to 60 wt%.

Description

Technical Field

[0001] The present invention relates to an organotin compound doped plastic scintillator, a preparation method thereof and an application thereof, belonging to the field of radiation detection. Background Art

[0002] A scintillator is a component of a scintillator detector that interacts with particles and can convert high-energy rays or high-energy particles into visible light or ultraviolet light through the action of ionizing radiation. As an optical functional material, it is widely used in the fields of high-energy physics, medical imaging, security inspection, industrial exploration, etc. At present, the inorganic scintillation crystals NaI:Tl and CsI:Tl are the most important scintillators for gamma-ray energy spectrum detection, but their disadvantages are easy deliquescence, high cost, difficulty in large-size preparation, and long decay time.

[0003] Plastic scintillators are generally made of polymerizable monomers as a matrix and polymerized by adding fluorescent substances, and have the advantages of good environmental stability, extremely low cost, easy large-size preparation, and fast decay. However, due to the low effective atomic number (Z eff ), traditional plastic scintillators can only achieve gamma-ray counting detection and lack energy spectrum detection ability. While plastic scintillators sensitized with high effective atomic numbers have increased Z eff , improving their gamma-ray stopping ability and having gamma-ray energy spectrum detection ability. In addition, plastic scintillators have fast neutron detection ability and can achieve gamma / neutron discrimination. Therefore, the development of plastic scintillators sensitized with high atomic numbers has received great attention. Although commercially available organoheavy metal compound doped plastic scintillators have been prepared at present, there are still limitations such as difficulty in achieving high-content doping of organoheavy metal compounds and heavy-atom fluorescence quenching effects. For example, the EJ-256 product doped with 5 wt% Pb from the American company Eljen still does not show energy resolution and the light yield drops sharply.

[0004] In summary, the development of organoheavy metal compound doped plastic scintillators with high effective atomic numbers, moderate light yields, gamma energy spectrum detection ability and gamma / neutron discrimination ability has high practical value in radiation detection fields such as portal security inspection. Summary of the Invention

[0005] In order to overcome the disadvantage that traditional plastic scintillators cannot perform energy spectrum detection, the purpose of the present invention is to provide an organotin compound doped plastic scintillator, a preparation method thereof and an application thereof.

[0006] In the first aspect, the present invention provides an organotin compound doped plastic scintillator, comprising: a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye and an organotin compound;

[0007] The content of the initiator in the organotin compound doped plastic scintillator is 0 to 1 wt%

[0008] The content of the fluorescent dye is 0.01-30 wt%.

[0009] The content of the crosslinking agent is 0-10 wt%.

[0010] The content of the organotin compound is 0.1-60 wt% (it can be 0.1-40 wt%, and higher 40-60 wt%).

[0011] Preferably, the general structural formula of the organotin compound is (R 1 ) x (R 2 ) 4-x Sn; wherein, x is 0, 1, 2, 3, or 4; R 1 is a linear or branched alkyl substituent, preferably selected from at least one of methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl; R 2 is at least one of a linear or branched substituent containing an unsaturated bond, a substituent containing a benzene ring or an aromatic heterocycle, a substituent containing a halogen, and a substituent containing an ester group or a carbonyl group.

[0012] Preferably, the linear or branched substituent containing an unsaturated bond is selected from at least one of vinyl, propenyl, 3-methyl-2-butenyl, propynyl, methynyl, 1-ethoxyvinyl, maleic acid group, acrylate, methyl methacrylate, vinyl methacrylate, and furfuryl methacrylate, etc.;

[0013] The substituent containing a benzene ring or an aromatic heterocycle is selected from at least one of phenyl, benzyl, phenethyl, phenylpropyl, furyl, thienyl, thiazolyl, imidazolyl, pyridyl, oxazolyl, styryl, methylstyryl, etc.;

[0014] The substituent containing a halogen is selected from at least one of fluorine, chlorine, bromine, iodine, iodomethyl, etc.;

[0015] The substituent containing an ester group or a carbonyl group is selected from at least one of 2-ethyl-hexyl ester group, ethyl ester group, propyl ester group, 2,4-pentanedione group, 2,2,6,6-tetramethyl-3,5-heptanedione group, etc. Generally, when the organotin compound is at 0.1-40 wt%, the crosslinking agent can be not added to achieve uniform doping. When the content of the organotin compound > 40 and ≤ 60 wt%, the crosslinking agent needs to be added to achieve uniform doping. In special cases, when R 2 in the organotin compound is at least one of a linear or branched substituent containing an unsaturated bond, styryl, methylstyryl, etc. (for example, tin of styrene group), the unsaturated double bond contained therein can participate in the copolymerization of the plastic matrix monomer, and high-content (40-60 wt%) doping can also be carried out without adding a crosslinking agent.

[0016] Preferably, the plastic matrix is ​​polymerized from matrix monomers containing active groups of unsaturated bonds; preferably selected from polymers synthesized from monomers containing vinyl groups and / or polymers synthesized from monomers containing terephthalate groups, more preferably at least one of polystyrene, polyvinyltoluene, poly(9-vinylcarbazole), polymethyl methacrylate, and polyethylene terephthalate.

[0017] Preferably, the initiator is selected from at least one of an azo initiator, a peroxide initiator and a photoinitiator, and is preferably selected from at least one of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, photoinitiator 184, photoinitiator BAPO, etc.

[0018] Preferably, the crosslinking agent is selected from at least one of substances containing multiple functional groups in the molecule or compounds containing multiple unsaturated double bonds in the molecule, preferably at least one of divinylbenzene (DVB), ethylene glycol dimethacrylate, bisphenol A dimethacrylate, etc.

[0019] Preferably, the fluorescent dye comprises a primary fluorescent dye and / or a wavelength shifter;

[0020] The primary fluorescent dye is selected from at least one of 2,5-diphenyloxazole, p-terphenyl, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2-(4-biphenyl)-5-phenyloxadiazole, etc.;

[0021] The wave shifting agent is selected from at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene (English abbreviation: POPOP), 1,4-bis(2-methylphenylvinyl)benzene, 1,4-di(4-methylphenylvinyl)benzene, 9,10-diphenylanthracene, coumarin 6, 7-diethylamino-4-methylcoumarin, etc.

[0022] In a second aspect, the present invention provides a method for preparing an organotin compound-doped plastic scintillator, comprising:

[0023] (1) In an inert atmosphere, a monomer of a plastic matrix, an initiator, a cross-linking agent, a fluorescent dye, and an organic tin compound are mixed to obtain a mixed solution;

[0024] (2) The mixed solution is sealed and polymerized at 40° C. to 120° C. for 1 to 4 weeks to obtain the organotin compound-doped plastic scintillator. For example, in the process of preparing the plastic scintillator, the organotin compound is doped into plastic monomers such as styrene and vinyl toluene according to a corresponding mass ratio and mixed thoroughly.

[0025] Thirdly, the present invention provides a method for preparing an organotin compound-doped plastic scintillator, comprising:

[0026] (1) In an inert atmosphere, mix the monomers of the plastic matrix, initiator, crosslinking agent, fluorescent dye and organotin compound, seal them and heat them for polymerization to obtain a solid material of the organotin compound-doped plastic scintillator. Add the solid material of the organotin compound-doped plastic scintillator into the hopper of an injection molding machine and tighten the mold with a clamping device;

[0027] (2) Under the action of a heater, the solid material in the barrel is fully heated by the rotation of the screw and shear force to obtain a resin in a molten flow state;

[0028] (3) Through the rotation of the screw, the molten resin is conveyed to the front end of the barrel, and continuously conveyed under pressure, and injected into the mold cavity from the gate through the main runner and sub-runners;

[0029] (4) After the resin fills the mold cavity and is kept under pressure for a certain time to cool and form, the obtained organotin compound-doped plastic scintillator is taken out through a demolding device and an ejection device.

[0030] Fourthly, the present invention provides a method for preparing an organotin compound-doped plastic scintillator, comprising:

[0031] (1) In an inert atmosphere, mix the monomers of the plastic matrix, initiator, crosslinking agent, fluorescent dye and organotin compound, seal them and heat them for polymerization to obtain a solid material of the organotin compound-doped plastic scintillator. Add the solid material of the organotin compound-doped plastic scintillator into the hopper of an extruder and install an extruding die orifice with a certain shape at the extruding die end;

[0032] (2) Under the action of a heater, the solid material in the barrel is fully heated by the rotation of the screw and shear force to obtain a molten resin;

[0033] (3) Through the rotation of the screw, the molten resin is conveyed to the front end of the barrel, and under the extrusion of the extruder screw or plunger, through the installed extruding die orifice, a continuously extruded and formed organotin compound-doped plastic scintillator product is obtained.

[0034] Fifthly, the present invention provides an application of an organotin compound-doped plastic scintillator in the field of radiation detection, and the field of radiation detection includes: X-ray detection, γ-ray detection, γ-ray energy spectrum detection and neutron / gamma pulse shape discrimination.

[0035] Beneficial effects:

[0036] The present invention discloses a preparation method and examples of an organotin compound-doped plastic scintillator. The plastic scintillator is composed of a matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound. The preparation methods include bulk polymerization, injection molding, and extrusion molding. Compared with the undoped plastic scintillator, the organotin compound-doped plastic scintillator prepared by the present invention not only retains the advantage of nanosecond-level fast decay of the plastic scintillator but also increases the ability to detect gamma-ray energy spectra;

[0037] In the present invention, the organotin compound-doped plastic scintillator has a high effective atomic number, a fast decay time, a moderate light yield, and good energy resolution, and can be applied to X-ray detection, gamma-ray energy spectrum detection, and gamma / neutron discrimination, and has important application prospects in radiation detection fields such as portal security inspection. Description of the Drawings

[0038] Figure 1 It is a sample photo of plastic scintillators doped with different concentrations of tributyl(1-ethoxyvinyl)tin under natural light in Example 1; the sample size is 10 mm in height and 15 mm in diameter;

[0039] Figure 2 It is the scintillation performance test of the tributyl(1-ethoxyvinyl)tin-doped plastic scintillator in Example 1. Among them, a is the X-ray excitation emission spectrum of plastic scintillators doped with different concentrations of tributyl(1-ethoxyvinyl)tin, b is the scintillation decay time of the 20 wt% tributyl(1-ethoxyvinyl)tin-doped plastic scintillator under 137 the excitation of a Cs source, c is the multi-channel energy spectrum of plastic scintillators doped with different concentrations of tributyl(1-ethoxyvinyl)tin under 137 the irradiation of a Cs source, and d is the multi-channel energy spectrum of the 20 wt% tributyl(1-ethoxyvinyl)tin-doped plastic scintillator under 137 the irradiation of a Cs source (the light yield and energy resolution are determined by comparison with the commercial inorganic scintillator BGO);

[0040] Figure 3 It is the scintillation performance test of the 40 wt% tributyl(1-ethoxyvinyl)tin-doped plastic scintillator in Example 1 (in this example, the wavelength shifter is coumarin 6). Among them, a is the X-ray excitation emission spectrum, b is 137 the scintillation decay time under the excitation of a Cs source, and c is the multi-channel energy spectrum under 137 the irradiation of a Cs source;

[0041] Figure 4 It is the sample photo of plastic scintillators doped with different concentrations of tributylphenyltin (a) and plastic scintillators doped with different concentrations of 2-tributylstannylthiophene (b) provided in Example 2 under natural light; the sample size is 10 mm in height and 15 mm in diameter;

[0042] Figure 5 Scintillation performance test of tributylphenyltin-doped plastic scintillator provided in Example 2. Where a is the X-ray excitation emission spectrum of tributylphenyltin-doped plastic scintillator with different concentrations, b is the scintillation decay time of 20 wt% tributylphenyltin-doped plastic scintillator under 137 excitation of Cs source, and c is the multi-channel energy spectrum of tributylphenyltin-doped plastic scintillator with different concentrations under 137 irradiation of Cs source;

[0043] Figure 6 Scintillation performance test of 2-tributylstannylthiophene-doped plastic scintillator provided in Example 2. Where a is the X-ray excitation emission spectrum of 2-tributylstannylthiophene-doped plastic scintillator with different concentrations, b is the scintillation decay time of 20 wt% 2-tributylstannylthiophene-doped plastic scintillator under 137 excitation of Cs source, and c is the multi-channel energy spectrum of 2-tributylstannylthiophene-doped plastic scintillator with different concentrations under 137 irradiation of Cs source;

[0044] Figure 7 Scintillation performance test of 40 wt% 2-tributylstannylthiophene-doped plastic scintillator provided in Example 2 (in this example, the wavelength shifter is coumarin 6). Where a is the X-ray excitation emission spectrum, and b is the scintillation decay time under 137 excitation of Cs source;

[0045] Figure 8 Sample photos of dibutyltin diacetate-doped plastic scintillator with different concentrations provided in Example 4 under natural light; the sample size is 10 mm in height and 15 mm in diameter;

[0046] Figure 9 Scintillation performance test of dibutyltin diacetate-doped plastic scintillator with different concentrations provided in Example 4. Where a is the X-ray excitation emission spectrum of dibutyltin diacetate-doped plastic scintillator, b is the scintillation decay time of 10 wt% dibutyltin diacetate-doped plastic scintillator under 137 excitation of Cs source, and c is the multi-channel energy spectrum of dibutyltin diacetate-doped plastic scintillator with different concentrations under 137 irradiation of Cs source;

[0047] Figure 10 Sample photos of 10 wt% different organotin compound-doped plastic scintillator provided in Example 5 under natural light; the sample size is 15 mm in height and 15 mm in diameter;

[0048] Figure 11Scintillation performance test of 10 wt% different organotin compound-doped plastic scintillators provided in Example 5. Among them, a is the X-ray excitation emission spectrum, and b is 137 Multi-channel energy spectrum diagram under Cs source irradiation. Specific implementation mode

[0049] The present invention will be further described below through the following implementation modes. It should be understood that the following implementation modes are only used to illustrate the present invention and do not limit the present invention.

[0050] In the present disclosure, the organotin compound-doped plastic scintillator is composed of a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound. Among them, the content of the initiator can be 0 to 1 wt% (weight percentage content); the content of the crosslinking agent can be 0 to 10 wt% (weight percentage content); the content of the fluorescent dye can be 0.01 to 30 wt% (weight percentage content); the content of the organotin compound can be 0 to 40 wt% (weight percentage content), or higher 40 to 60 wt% (weight percentage content).

[0051] In an alternative embodiment, the initiator or crosslinking agent is used to shorten the polymerization time of the high-content organotin compound-doped plastic scintillator, and the initiator or crosslinking agent may not be added under low-content doping.

[0052] In an alternative embodiment, the organotin compound may have the following structure: formula (R 1 ) x (R 2 ) 4-x Sn organotin compound, where R 1 is a straight-chain or branched-chain alkyl substituent, R 2 is a straight-chain or branched-chain substituent containing an unsaturated bond, and x is an integer between 0 and 4. Typical examples of R 1 include but are not limited to methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl. Typical examples of R 2 include but are not limited to vinyl, propenyl, 3-methyl-2-butenyl, propynyl, methynyl, 1-ethoxyvinyl, maleic acid group, acrylate, methyl methacrylate, vinyl methacrylate, and furfuryl methacrylate. The content of the organotin compound can be 0.1 to 60 wt%, preferably 3 to 40 wt%, more preferably 10 to 30 wt%.

[0053] Among them, γ-rays deposit their energy on one or more electrons in the detector material through Compton scattering and the photoelectric effect with the scintillator. After the electrons de-excite, visible light is generated. Among them, the photoelectric effect depends on the effective atomic number (Z eff ), and is related to Z effIs proportional to the fourth power. The plastic scintillator of the undoped organotin compound only contains light elements such as carbon, hydrogen, oxygen, and nitrogen. The Z of the material eff Is small. Gamma rays can only interact with the plastic scintillator in the form of Compton scattering, and only gamma ray counting detection can be achieved, lacking the ability of energy spectrum detection. While the plastic scintillator doped with organotin compounds has a high Z eff Organic heavy metal compounds such as organotin and lead compounds improve the Z of the plastic scintillator eff , Improve its stopping ability for gamma rays, increase the energy deposition in the form of the photoelectric effect, and thus gamma ray energy spectrum detection can be achieved. In addition, since the introduction of organotin compounds only plays the role of increasing energy deposition and does not introduce new slow luminescence centers, the fast decay characteristics of the plastic scintillator are still retained. If the amount of organotin compound added is insufficient, it will lead to a low effective atomic number Ze ff Of the material, it is difficult to deposit energy by the photoelectric effect, and it is impossible to form a photoelectric effect peak, resulting in poor gamma ray detection ability. If the amount of organotin compound added is too high, the following two situations will occur: (1) Exceeding the solubility limit causes the doped compound to precipitate during the polymerization of the plastic scintillator, making the plastic scintillator opaque; (2) Making it difficult for the doped plastic scintillator to polymerize, and the prepared sample is difficult to form or is too soft to be processed subsequently.

[0054] In an alternative embodiment, the organotin compound may have the following structure: formula (R 1 ) x (R 2 ) 4-x Organotin compounds of Sn, where R 1 Is a straight-chain or branched-chain alkyl substituent, and R 2 Is a substituent containing a benzene ring or an aromatic heterocycle, and x is an integer between 0 and 4. Typical examples of R 1 Include but are not limited to methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl. Typical examples of R 2 Include but are not limited to phenyl, benzyl, phenethyl, phenylpropyl, furyl, thienyl, thiazolyl, imidazolyl, pyridyl, oxazolyl, styryl, or methylstyryl. The content of the organotin compound can be 0.1 to 60 wt%, preferably 3 to 40 wt%, more preferably 10 to 30 wt%.

[0055] In an alternative embodiment, the organotin compound may have the following structure: formula (R 1 ) x (R 2 ) 4-x Organotin compounds of Sn, where R 1 Is a straight-chain or branched-chain alkyl substituent, and R 2 Is a halogen-containing substituent, and x is an integer between 0 and 4. R1 Typical examples include, but are not limited to, methyl, ethyl, propyl, butyl, isopropyl and tert-butyl. R 2 Typical examples include, but are not limited to, fluorine, chlorine, bromine, iodine, iodomethyl. The content of the organotin compound can be 0.1 to 40 wt%, preferably 3 to 30 wt%, more preferably 10 to 20 wt%.

[0056] In an alternative embodiment, the organotin compound may have the following structure: formula (R 1 ) x (R 2 ) 4-x Sn organotin compounds, where R 1 is a linear or branched alkyl substituent, R 2 is a substituent containing an ester group or a carbonyl group, and x is an integer between 0 and 4. R 1 Typical examples include, but are not limited to, methyl, ethyl, propyl, butyl, isopropyl and tert-butyl. R 2 Typical examples include, but are not limited to, 2-ethyl-hexyl ester group, ethyl ester group, propyl ester group, 2,4-pentanedione group, 2,2,6,6-tetramethyl-3,5-heptanedione group. The content of the organotin compound can be 0.1 to 40 wt%, preferably 5 to 30 wt%, more preferably 10 to 20 wt%.

[0057] The following exemplarily describes the method for preparing an organotin compound-doped plastic scintillator by bulk polymerization.

[0058] Step 1: Wash the glass reaction vessel three times successively with deionized water, ethanol, and acetone, and then place it in an oven for overnight vacuum heating and drying.

[0059] Step 2: In an inert atmosphere, add the matrix monomer, initiator (0 to 1 wt%), crosslinking agent (0 to 10 wt%), fluorescent dye (0.01 to 30 wt%), and organotin compound to the glass reaction vessel cleaned in Step 1, and dissolve them at room temperature or by ultrasonic treatment to obtain a homogeneous solution system.

[0060] Step 3: After sealing the glass reaction vessel containing the mixed solution in Step 2, place it in an oven or use a heat transfer fluid (oil, water, etc.) to raise the temperature to the specified polymerization temperature and keep it at that temperature for polymerization for several days. Depending on the properties and doping amount of the added organotin compound, the selected polymerization temperature and polymerization time also vary in part. Organotin compounds with low boiling points and low doping contents are usually polymerized at 40 - 100 °C for several weeks, and higher doping amounts may require longer times; organotin compounds with high boiling points and low doping contents can be polymerized at 60 - 120 °C for several weeks, and higher doping amounts may require longer times.

[0061] Step 4: After the polymerization is completed, slowly cool the temperature to room temperature to reduce internal stress. Take out the cured product from the glass container, cut and polish it to obtain the desired organotin compound-doped plastic scintillator.

[0062] As a further preferred solution, the matrix monomer should be purified to remove stabilizers and water, and the purity of other raw materials should be above 95%. The batching environment is an inert gas environment (a glove operating box filled with argon or nitrogen).

[0063] The following exemplarily describes the method for preparing an organotin compound-doped plastic scintillator by injection molding.

[0064] Step 1: In an inert atmosphere, mix the plastic matrix, initiator, crosslinker, fluorescent dye and organotin compound, seal it and heat it for polymerization to obtain a solid material of the organotin compound-doped plastic scintillator. Add the prepared solid material into the hopper of the injection molding machine and tighten the mold with the clamping device.

[0065] Step 2: Under the action of the heater, the solid material in the barrel in Step 1 is fully heated to a molten flow state by the rotation and shear force of the screw and further mixed evenly.

[0066] Step 3: Through the rotation of the screw, the molten resin in Step 2 is conveyed to the front end of the barrel, continuously transmitted under high pressure, and injected into the mold cavity from the gate through the main runner and the sub-runners.

[0067] Step 4: After the resin fills the mold cavity and is kept under pressure for a period of time to cool and form, the prepared plastic scintillator product can be taken out through the demolding device and the ejector device.

[0068] As a further preferred solution, to improve the final optical quality of the plastic scintillator, it is very important to keep the raw materials clean during the barrel mixing step as they are easily contaminated. The solid material of the doped plastic scintillator or the mixed prepolymer resin should be purified to remove impurities and water, and the entire preparation process should be in an inert gas environment (argon or nitrogen) to eliminate the influence of humidity and oxygen.

[0069] The following exemplarily describes the method for preparing an organotin compound-doped plastic scintillator by extrusion molding.

[0070] Step 1: In an inert atmosphere, mix the plastic matrix, initiator, crosslinker, fluorescent dye and organotin compound, seal it and heat it for polymerization to obtain a solid material of the organotin compound-doped plastic scintillator. Add the prepared solid material into the hopper of the extruder and install a die of a certain shape at the extrusion die end.

[0071] Step 2: Under the action of the heater, the solid material in the barrel in Step 1 is fully heated by the rotation and shear force of the screw to become a molten and flowing state, and is further mixed evenly.

[0072] Step 3: The molten resin in Step 2 is conveyed to the front end of the barrel by the rotation of the screw. Under the extrusion action of the extruder screw or the plunger, continuous extrusion-molded plastic scintillator products can be obtained through the extrusion die installed in Step 1.

[0073] As a further preferred solution, in the barrel mixing step, the raw materials are vulnerable to contamination, and it is very important to keep them clean. The solid material doped with plastic scintillator or the well-mixed prepolymer resin should be purified to remove impurities and water. A complex drying procedure with a nitrogen purging system throughout the preparation process can eliminate the influence of humidity and reduce the problem of plastic degradation due to the presence of oxygen, improving the final optical quality of the plastic scintillator.

[0074] The following further exemplifies embodiments to illustrate the present invention in detail. It should also be understood that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, rather than being limited to the specific values in the following examples. Different organotin compounds are selected in the following examples for doping at different concentrations, and plastic scintillators with different optical and scintillation properties can be obtained.

[0075] Example 1

[0076] In this Example 1, one or two of the organotin compounds of the formula (R 1 ) x (R 2 ) 4-x Sn are doped at different concentrations, where R 1 is a linear or branched alkyl substituent, R 2 is a linear or branched substituent containing an unsaturated bond, and x is an integer between 0 and 4. Specifically, tributyl(1-ethoxyethylene)tin included therein is selected.

[0077] The preparation method of the above organotin compound-doped plastic scintillator includes the following steps:

[0078] In an inert atmosphere, the matrix monomer (vinyltoluene, abbreviated as VT), primary fluorescent dye (PPO), wavelength shifter (POPOP), and tributyl(1-ethoxyvinyl)tin with different doping amounts (ranging from 0 to 60 wt%, such as 0 wt%, 3 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%) are added to a cleaned and dried glass reaction vessel and dissolved at room temperature or by ultrasonic treatment to obtain a homogeneous solution system. After sealing the glass reaction vessel, it is placed in an oil bath and heated to the specified polymerization temperature and maintained for polymerization for several days. For plastic scintillators with a doping amount of 10 wt% and below, polymerization at 40 - 70 °C for three weeks is usually selected. Higher doping amounts (≤30 wt%) may require one month. Due to the solubility limit of POPOP, for higher doping amounts such as 40 - 60 wt%, a more soluble wavelength shifter (coumarin 6) is selected; and due to the increase in doping amount, the polymerization time is longer, and the prepared doped plastic scintillator is prone to softening and difficult to process. Therefore, a crosslinking agent (divinylbenzene, abbreviated as DVB) is newly added to the formulation to increase its polymerization rate and hardness. After process optimization, the high-doping plastic scintillator usually completes polymerization at 40 - 70 °C for three weeks. After polymerization, the temperature is slowly lowered to room temperature to reduce internal stress. The cured product is taken out of the glass container, cut and polished to obtain the doped plastic scintillator. For plastic scintillators with higher doping amounts such as 50 wt% and 60 wt%, due to excessive doping, organotin compounds precipitate, and due to too fast crosslinking speed, it becomes opaque.

[0079] As Figure 2 shown in a of, the X-ray excitation emission spectrum test results show that the emission peaks in the XEL of the tributyl(1-ethoxyvinyl)tin-doped plastic scintillator all originate from the wavelength shifter POPOP; and as the doping concentration of tributyl(1-ethoxyvinyl)tin increases, the XEL intensity is significantly higher than that of the undoped plastic scintillator, and the XEL intensity is the highest at 10 wt%; as Figure 2 shown in b of, 137 The scintillation decay time test results under Cs excitation show that the tributyl(1-ethoxyvinyl)tin-doped plastic scintillator still retains the fast decay characteristics of traditional plastic scintillators, and the decay time is about 4 ns;

[0080] In the present invention, the light yield of the plastic scintillator is measured by a relative method. As Figure 2 shown in c of, through 137 The multi-channel energy spectrum test results under Cs excitation show that as the doping concentration of tributyl(1-ethoxyvinyl)tin increases, the scintillation light yield decreases compared to the undoped plastic scintillator, but the counting rate increases by about two times, and a full-energy peak appears. The specific light yield and energy resolution are obtained by comparison with a commercial inorganic scintillator BGO (size: 14×14×5 mm), asFigure 2 As shown in d, the light yield is 7500 photons / MeV, and the energy resolution is approximately 16.3% @ 662 keV;

[0081] As Figure 3 shown in a, the test results of X-ray excited emission spectrum indicate that the emission peak in the XEL of the plastic scintillator doped with 40 wt% tributyl(1-ethoxyvinyl)tin originates from the wavelength shifter coumarin 6;

[0082] As Figure 3 shown in b, 137 The test results of the scintillation decay time under Cs excitation indicate that the plastic scintillator doped with 40 wt% tributyl(1-ethoxyvinyl)tin still retains the fast decay characteristic of the traditional plastic scintillator, and the decay time is approximately 6 ns;

[0083] As Figure 3 shown in c, through 137 The test results of the multi-channel energy spectrum under Cs excitation indicate that a higher concentration of tin doping increases the counting rate of the plastic scintillator. However, due to the deviation of the emission peak position of coumarin 6 from the sensitive band of the PMT (R2059) used in the test, and affected by the detection efficiency, no obvious full-energy peak appears. The above-mentioned plastic scintillator doped with tributyl(1-ethoxyvinyl)tin can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0084] Example 2

[0085] In this Example 2, one or two of the organotin compounds of the formula (R 1 ) x (R 2 ) 4-x Sn are doped at different concentrations, where R 1 is a straight-chain or branched-chain alkyl substituent, R 2 is a benzene ring-containing or heterocyclic substituent, and x is an integer between 0 and 4. Specifically, tributylphenyltin and 2-tributylstannylthiophene included therein are selected.

[0086] The preparation method of the above two organotin compound-doped plastic scintillators includes the following steps:

[0087] In an inert atmosphere, the matrix monomer (VT), initiator (AIBN), primary fluorescent dye (PPO), wavelength shifter (POPOP), and tributylphenyltin with different doping amounts (0 - 20 wt%, such as 0 wt%, 3 wt%, 7 wt%, 20 wt%) and 2 - tributylstannylthiophene (0 - 60 wt%, such as 0 wt%, 3 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 60 wt%) are added to a cleaned and dried glass reaction vessel and dissolved at room temperature or by ultrasonic treatment to obtain a homogeneous solution system. After sealing the glass reaction vessel, it is placed in an oil bath and heated to the specified polymerization temperature and maintained for polymerization for several days. Plastic scintillators with a doping amount of 10 wt% and below usually undergo polymerization at 40 - 70 °C for three weeks, while higher doping amounts (20 wt%) are polymerized at 90 °C for one month. Due to the solubility limit of POPOP, for higher doping amounts such as 40 - 60 wt%, a more soluble wavelength shifter (coumarin 6) is selected; and due to the increase in doping amount, the polymerization time is longer, and the prepared doped plastic scintillator is prone to becoming soft and difficult to process. Therefore, a crosslinking agent (DVB) is newly added to the formulation to increase its polymerization rate and hardness. After process optimization, plastic scintillators with high doping amounts usually complete polymerization after three weeks of polymerization at 40 - 70 °C. After polymerization, the temperature is slowly lowered to room temperature to reduce internal stress. The cured product is taken out of the glass container, cut and polished to obtain a doped plastic scintillator. However, for plastic scintillators with higher doping amounts such as 50 wt% and 60 wt%, due to excessive doping, the doped compounds precipitate and are opaque.

[0088] As Figure 5 shown in a of [reference], the X-ray excitation emission spectrum test results show that the emission peaks in the XEL of the plastic scintillator doped with tributylphenyltin all originate from the wavelength shifter POPOP; compared with the undoped plastic scintillator, the XEL intensity is the highest at a doping amount of 3 wt%.

[0089] As Figure 5 shown in b of [reference], 137 the scintillation decay time test results under Cs excitation show that the plastic scintillator doped with tributylphenyl organotin compounds still retains the fast decay characteristic of traditional plastic scintillators, with a decay time of 4.1 ns.

[0090] As Figure 5 shown in c of [reference], through 137 the multi-channel energy spectrum test results under Cs excitation show that as the doping concentration of tributylphenyltin increases, the scintillation light yield decreases compared to the undoped plastic scintillator, but the counting rate increases and a full-energy peak appears.

[0091] As Figure 6As shown in a, the X-ray excited emission spectrum test results indicate that the emission peaks in the XEL of the plastic scintillator doped with 2-tributylstannylthiophene all originate from the wavelength shifter POPOP; and as the doping concentration of 2-tributylstannylthiophene increases, the XEL intensity is significantly higher than that of the undoped plastic scintillator, and the XEL intensity is the highest with a doping of 3wt%;

[0092] As Figure 6 shown in b; 137 The scintillation decay time test results under Cs excitation show that the 2-tributylstannylthiophene-doped plastic scintillator still retains the fast decay characteristic of the traditional plastic scintillator, and the decay time is about 4.1 ns;

[0093] As Figure 6 shown in c, through 137 the multi-channel energy spectrum test results under Cs excitation show that as the doping concentration of 2-tributylstannylthiophene increases, the scintillation light yield decreases compared to the undoped plastic scintillator, but the counting rate increases and a full energy peak appears;

[0094] As Figure 7 shown in a, the X-ray excited emission spectrum test results indicate that the emission peaks in the XEL of the plastic scintillator doped with 40wt% 2-tributylstannylthiophene originate from the wavelength shifter coumarin 6;

[0095] As Figure 7 shown in b; 137 The scintillation decay time test results under Cs excitation show that the plastic scintillator doped with 40wt% 2-tributylstannylthiophene still retains the fast decay characteristic of the traditional plastic scintillator, and the decay time is about 6 ns;

[0096] The above-mentioned plastic scintillators doped with tributylphenyltin and 2-tributylstannylthiophene can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0097] Example 3

[0098] In this Example 3, one or two of the organotin compounds of the formula (R 1 ) x (R 2 ) 4-x Sn are doped at different concentrations, where R 1 is a linear or branched alkyl substituent, R 2 is a halogen-containing substituent, and x is an integer between 0 and 4. Specifically, tributyl(iodomethyl)stannane included therein is selected.

[0099] The preparation method of the above-mentioned organotin compound-doped plastic scintillator includes the following steps:

[0100] In an inert atmosphere, the matrix monomer (VT), initiator (AIBN), primary fluorescent dye (PPO), wavelength shifter (POPOP), and dibutyl(iodomethyl)stannane with different doping amounts (0 - 20 wt%, such as 0 wt%, 10 wt%, 20 wt%) are added to a cleaned and dried glass reaction vessel and dissolved at room temperature or by ultrasonic treatment to obtain a homogeneous solution system. After sealing the glass reaction vessel, it is placed in an oil bath and heated to a specified polymerization temperature and maintained for polymerization for several days. Usually, for doping amounts below 10 wt%, polymerization is carried out at 40 - 80 °C for three weeks, and higher doping amounts may require longer times. After polymerization is completed, the temperature is slowly lowered to room temperature to reduce internal stress. The solidified product is taken out of the glass container, cut and polished to obtain a doped plastic scintillator. The above-mentioned plastic scintillator doped with dibutyl(iodomethyl)stannane can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0101] Example 4

[0102] In this Example 4, one or two of the organotin compounds of the formula (R 1 ) x (R 2 ) 4-x Sn are doped at different concentrations, where R 1 is a linear or branched alkyl substituent, R 2 is a substituent containing an ester group or a carbonyl group, and x is an integer between 0 and 4. Specifically, dibutyltin diacetate included therein is selected.

[0103] The preparation method of the above-mentioned plastic scintillator doped with organotin compounds includes the following steps:

[0104] In an inert atmosphere, the matrix monomer (VT), primary fluorescent dye (PPO), wavelength shifter (POPOP), and dibutyltin diacetate with different doping amounts (0 - 20 wt%, such as 0 wt%, 6 wt%, 10 wt%, 20 wt%) are added to a cleaned and dried glass reaction vessel and dissolved at room temperature or by ultrasonic treatment to obtain a homogeneous solution system. After sealing the glass reaction vessel, it is placed in an oil bath and heated to a specified polymerization temperature and maintained for polymerization for several days. Usually, for doping amounts below 10 wt%, polymerization is carried out at 40 - 70 °C for three weeks, and for a high doping amount (20 wt%), polymerization is carried out at 90 °C for one month. After polymerization is completed, the temperature is slowly lowered to room temperature to reduce internal stress. The solidified product is taken out of the glass container, cut and polished to obtain a doped plastic scintillator.

[0105] As Figure 9As shown in a, the test results of X-ray excited emission spectra show that the emission peaks in the XEL of the dibutyltin diacetate compound-doped plastic scintillator all originate from the wavelength shifter POPOP; among them, the XEL intensity of the plastic scintillator doped with 6 wt% dibutyltin diacetate is significantly higher than that of the undoped plastic scintillator;

[0106] As Figure 9 shown in b, 137 The test results of the scintillation decay time under Cs excitation show that the dibutyltin diacetate compound-doped plastic scintillator still retains the fast decay characteristic of the traditional plastic scintillator, and the decay time is 3.6 ns;

[0107] As Figure 9 shown in c, through 137 The test results of the multi-channel energy spectrum under Cs excitation show that with the increase of the doping concentration of dibutyltin diacetate, the scintillation light yield decreases compared with the undoped plastic scintillator, but the counting rate increases and a full-energy peak appears; the above-mentioned dibutyltin diacetate-doped plastic scintillator can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0108] Example 5

[0109] In this Example 5, an organotin compound with the formula (R 1 ) 3 (R 2 )Sn is selected, where R 1 is butyl, and R 2 is one of a linear or branched substituent containing an unsaturated bond, a substituent containing a benzene ring or an aromatic heterocycle, a substituent containing a halogen, and a substituent containing an ester group or a carbonyl group. Specifically, plastic scintillators are prepared by selecting organotin compounds with the same doping amount of 10 wt% and different structures, and the performance differences are compared.

[0110] The preparation method of the above organotin compound-doped plastic scintillator includes the following steps:

[0111] In an inert atmosphere, the matrix monomer (VT), primary fluorescent dye (PPO), wavelength shifter (POPOP), and an organotin compound with a doping amount of 10 wt% (allyltributyltin, 2-(tributylstannyl)pyridine, 2-(tributylstannyl)thiophene, 2-(tributylstannyl)furan, tributyl(iodomethyl)stannane) are added to a cleaned and dried glass reaction vessel and dissolved at room temperature or by ultrasonic treatment to obtain a homogeneous solution system. After sealing the glass reaction vessel, it is placed in an oil bath and heated to the specified polymerization temperature and kept at that temperature for several days for polymerization. In the case of no initiator added, polymerization is usually carried out at 50 - 100 °C for ten days with a doping amount below 10 wt%. After the polymerization is completed, the temperature is slowly lowered to room temperature to reduce internal stress. The cured product is taken out of the glass container, cut and polished to obtain a doped plastic scintillator.

[0112] As Figure 11 shown in a of [reference], the test results of X-ray excitation emission spectra indicate that the emission peaks in the XEL of plastic scintillators doped with different organotin compounds all originate from the wavelength shifter POPOP;

[0113] As Figure 11 shown in b of [reference], through 137 the test results of multi-channel energy spectra under Cs excitation indicate that different organotin compounds have different effects on the light yield, but due to the doping of tin compounds, the counting rate of the plastic scintillator is increased and a full-energy peak appears;

[0114] The above-mentioned doped plastic scintillators can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0115] Example 6

[0116] In this Example 6, an organotin compound-doped plastic scintillator is prepared by an injection molding method, and the solid material of any one of the organotin compound-doped plastic scintillators in the above structures or the premixed prepolymer resin can be selected. Specifically, the tributyltin-based methacrylate-doped plastic scintillator included therein is selected.

[0117] The above-mentioned method for preparing an organotin compound-doped plastic scintillator by injection molding includes the following steps:

[0118] In an inert atmosphere, a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound are mixed, sealed, and heated for polymerization to obtain a solid material of tributyltin-based methacrylate-doped plastic scintillator. In an inert atmosphere, the prepared solid material is added to the hopper of an injection molding machine, and the mold is tightened with a mold clamping device. Under the action of a 150 °C heater, the solid material added to the barrel is sufficiently heated by the rotation of the screw to become a molten state, and after further mixing evenly, it is conveyed to the front end of the barrel and injected into the mold cavity through the sprue and runner from the gate. After the molten resin fills the mold cavity, it is kept under pressure for 5 min to cool and form, and the prepared tributyltin-based methacrylate plastic scintillator product can be taken out through the demolding device and the ejector device.

[0119] The above-mentioned tributyltin-based methacrylate-doped plastic scintillator can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

[0120] Example 7

[0121] In this Example 7, an organotin compound-doped plastic scintillator is prepared by an extrusion molding method, and the solid material of any one of the organotin compound-doped plastic scintillators in the above structures or the mixed prepolymer resin can be selected. Specifically, the tributyltin-based methacrylate-doped plastic scintillator included therein is selected.

[0122] The above method for preparing an organotin compound-doped plastic scintillator by extrusion includes the following steps:

[0123] In an inert atmosphere, a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound are mixed, sealed, and heated for polymerization to obtain a solid material of tributyltin-based methacrylate-doped plastic scintillator. In an inert atmosphere, the prepared solid material is added to the hopper of an extruder. Under the action of a 150 °C heater, the solid material added to the barrel is sufficiently heated by the rotation of the screw to become a molten state, and after further mixing evenly, it is conveyed to the front end of the barrel. Under the extrusion action, the plastic is extruded from a circular die with a diameter of 5 mm, and a cylindrical plastic scintillator product with a diameter of 5 mm in continuous extrusion molding can be obtained after cooling for 5 min.

[0124] The above-mentioned tributyltin-based methacrylate-doped plastic scintillator can be applied to radiation detection fields such as X-ray detection, γ-ray energy spectrum detection, and gamma / neutron discrimination.

Claims

1. An organotin compound-doped plastic scintillator, characterized in that, it comprises: a plastic matrix, an initiator, a crosslinking agent, a fluorescent dye, and an organotin compound; the content of the initiator in the organotin compound-doped plastic scintillator is 0-1 wt%; the content of the fluorescent dye is 0.01-30 wt%; the content of the crosslinking agent is 0-10 wt%; the content of the organotin compound is 0.1-60 wt%; the organotin compound is selected from tributyl(1-ethoxyvinyl)tin, tributylphenyltin, tributyl(iodomethyl)stannane, dibutyltin diacetate, allyltributyltin, 2-(tributylstannyl)pyridine, 2-(tributylstannyl)thiophene, 2-(tributylstannyl)furan, tributyltin methacrylate.

2. The organotin compound-doped plastic scintillator according to claim 1, characterized in that, the plastic matrix is a polymer synthesized from a vinyl-containing monomer and / or a polymer synthesized from a terephthalate group-containing monomer.

3. The organotin compound-doped plastic scintillator according to claim 2, characterized in that, the plastic matrix is at least one of polystyrene, polyvinyltoluene, poly(9-vinylcarbazole), polymethyl methacrylate, polyethylene terephthalate.

4. The organotin compound-doped plastic scintillator according to claim 1, characterized in that, the initiator is selected from at least one of azo initiators, peroxide initiators, and photoinitiators.

5. The organotin compound-doped plastic scintillator according to claim 4, characterized in that, the initiator is selected from at least one of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptonitrile, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide, photoinitiator 184, photoinitiator BAPO.

6. The organotin compound-doped plastic scintillator according to claim 1, characterized in that, the crosslinking agent is selected from at least one of divinylbenzene, ethylene glycol dimethacrylate, bisphenol A dimethacrylate.

7. The organotin compound-doped plastic scintillator according to claim 1, characterized in that, the fluorescent dye comprises a primary fluorescent dye and / or a wavelength shifter; the primary fluorescent dye is selected from at least one of 2,5-diphenyloxazole, p-terphenyl, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 2-(4-biphenyl)-5-phenyloxadiazole; the wavelength shifter is selected from at least one of 1,4-bis(5-phenyl-2-oxazolyl)benzene, 1,4-bis(2-methylstyryl)benzene, 1,4-bis(4-methylstyryl)benzene, 9,10-diphenylanthracene, coumarin 6, 7-diethylamino-4-methylcoumarin.

8. A method for preparing the organotin compound-doped plastic scintillator according to any one of claims 1-7, characterized in that, it comprises: (1) In an inert atmosphere, mixing the monomers of the plastic matrix, the initiator, the crosslinking agent, the fluorescent dye, and the organotin compound to obtain a mixed solution; (2) Seal the mixed solution and polymerize it at 40 - 120 °C for 1 - 4 weeks to obtain the organotin compound-doped plastic scintillator.

9. A method for preparing an organotin compound-doped plastic scintillator according to any one of claims 1 - 7, characterized in that, it comprises: (1) In an inert atmosphere, mix the monomer of the plastic matrix, initiator, crosslinking agent, fluorescent dye and organotin compound, seal it and heat it for polymerization to obtain the solid material of the organotin compound-doped plastic scintillator; then add the solid material of the organotin compound-doped plastic scintillator into the hopper of the injection molding machine and tighten the mold with the mold clamping device; (2) Under the action of the heater, the solid material in the barrel is fully heated by the rotation and shear force of the screw to obtain a resin in a molten flow state; (3) The molten resin is conveyed to the front end of the barrel by the rotation of the screw and continuously transported under pressure, and is injected into the mold cavity from the gate through the main runner and sub-runners; (4) After the resin fills the mold cavity, keep it under pressure for a certain time to cool and form, and then take out the obtained organotin compound-doped plastic scintillator through the demolding device and ejection device.

10. A method for preparing an organotin compound-doped plastic scintillator according to any one of claims 1 - 7, characterized in that, it comprises: (1) In an inert atmosphere, mix the monomer of the plastic matrix, initiator, crosslinking agent, fluorescent dye and organotin compound, seal it and heat it for polymerization to obtain the solid material of the organotin compound-doped plastic scintillator; then add the solid material of the organotin compound-doped plastic scintillator into the hopper of the extruder and install an extruder die of a certain shape at the extrusion die end; (2) Under the action of the heater, the solid material in the barrel is fully heated by the rotation and shear force of the screw to obtain a molten resin; (3) The molten resin is conveyed to the front end of the barrel by the rotation of the screw, and under the extrusion of the extruder screw or plunger, through the installed extruder die, a continuously extruded and formed organotin compound-doped plastic scintillator product is obtained.

11. An application of an organotin compound-doped plastic scintillator according to any one of claims 1 - 7 in the field of radiation detection, characterized in that, the field of radiation detection includes: X-ray detection, γ-ray detection and neutron / gamma pulse shape discrimination.

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