RU2039760C1 - Method of preparing polymeric fibre-optics overemitter - Google Patents

Abstract

FIELD: scintillation engineering. SUBSTANCE: overmitting addition (coumarin-30) is added to the polymerizing mixture containing 95-99 wt.-% methylmethacrylate, 1-5 wt. -% alkylacrylate-C₁-C₄, lauroyl peroxide and lauroylmercaptan. In layers polymerization is carried out at the rate 1-2 cm/h at 50-70 C, and obtained blocks were subjected for coextrusion with polyfluoroacrylate at 190-200 C for 20-30 min. EFFECT: improved method of polymeric substance preparing. 2 cl, 1 tbl

Description

 The invention relates to a scintillation technique, in particular, to a method for producing a polymer fiber optic re-emitter (FOP), which is used to collect light from a scintillator in a scintillation plate-fiber optic re-emitter-optical fiber (optical fiber) photodetector system.

 The main indicators of the quality of the re-emitter are the light output (absorption length of at least 100 cm), the efficiency of recording the passage of particles through the sample (the minimum number of photoelectrons should be at least 1).

 Closest to the proposed method in technical essence is a method for producing a GP, which consists in the fact that a toluene is removed from a bilayer fiber containing a polystyrene core and a polymethyl methacrylate (PMMA) sheath, and a 7-diethylamino-re-emitting additive is applied to the core in a toluene solution 3- (1-methylbenzimidazolyl-2) coumarin (coumarin-30), then the solvent is removed. Dyed fiber in this form is used as BOC. With this method, the surface of the core will inevitably deteriorate, and the re-emitting additive is distributed unevenly over the surface of the fiber. As a result of this, the efficiency of recording the passage of particles through a sample varies greatly along the length of the fiber and gives a large spread of indicators, which leads to a decrease in the light output (absorption length is 10-20 cm) and the registration efficiency is up to 0.7.

 The aim of the invention is to increase the light output and particle detection efficiency.

This goal is achieved by the fact that in the method for producing a polymer fiber-optic re-emitter containing a core based on polymethyl methacrylate with a re-emitting additive of 7-diethylamino-3- (1-methylbenzimidazolyl-2) coumarin, a re-emitting additive in an amount of 0.03-0.07 wt. .h. per 100 wt. including the monomer mixture is introduced into the polymerization mixture containing 95-99 wt. methyl methacrylate, 1-5 wt. alkyl acrylate C ₁ -C ₄ , 0.15-0.2 parts by weight per 100 parts by weight monomer mixture of lauroyl peroxide, 0.55-0.6 wt.h. lauryl mercaptan, polymerization was carried layered with a rate of 1-2 cm / hr at a temperature of 50-70 ^{° C} and the resulting blocks are subjected to coextrusion poliftorakrilatom at a temperature of 190-200 ^{° C} for 20-30 min.

 To further increase the absorption length and the efficiency of registration of particles in the polymerization mixture, you can additionally enter 3-5 wt.h. naphthalene.

PRI me R 1. The polymerization mixture containing 95 wt. methyl methacrylate (MMA), 5 wt. methyl acrylate (MA), 0.2 wt.h. peroxide of lauroyl (PL), 0.55 wt. including laurylmecrcaptan (LMC), 0.05 parts by weight 7-diethylamino-3- (1-methylbenzimidazolyl-2) coumarin (coumarin-30) is purified from mechanical impurities by microfiltration and polymerized in glass ampoules by immersing the ampoules with the reaction mixture at a speed of 2 cm / h in a thermostatic liquid at a temperature of 70 ^about C. After complete immersion, the ampoules are kept at 70 ^about 5 hours, followed by heating at 120 ^about C for 1.5 hours to exhaust the residual monomer.

The resulting blocks are used to form the core of a bicomponent fiber. A fluorine-based polymer based on tetrafluoropropyl fluoroacrylate (FN-1) is used as the shell material. The bicomponent fiber (GPs) with a diameter of 1 mm was prepared by co-extrusion at a temperature of 190 ^C and a time of the polymer being in the heated chamber for 20 minutes.

The quality of the VOP was evaluated by two indicators: the absorption length λ and the particle registration efficiency N _fe λ is estimated as the size of the segment in cm, at which the light signal decreases by a factor of l.

N _fe was estimated in this way: a GP sample was placed between scintillation counters and irradiated with a collimated radioactive source Ru ¹⁰⁶ . From the number of registered photons passing through the sample, N _{ph is calculated} .

The table shows the values of λ and N _fe .

 PRI me R 2. In example 1, use a polymerization mixture containing 99 wt. MMA, 1 wt. ethyl acrylate (EA), PL 0.15 parts by weight LMK 0.55 parts by weight coumarin 30 0.03 parts by weight

Polymerization mode: temperature 60 ^о С, ampoule immersion speed 1.5 cm / h.

Coextrusion Mode: temperature 200 ^C, time 30 min, using tetraftorpropilmetakrilat (MN-1) as the sheath material.

The values of the indicators λ and N _FE are shown in the table.

 PRI me R 3. In example 1, use a polymerization mixture containing 97 wt. MMA, 3 wt. butyl acrylate (BA), 0.2 wt.h. PL, 0.55 parts by weight LMK, 0.07 parts by weight coumarin-30.

Polymerization mode: temperature -50 ^о С, ampoule immersion speed 1 cm / h.

Extrusion mode: temperature 200 ^о С, time 25 min. The values of the indicators λ and N _FE are shown in the table.

 PRI me R 4. According to example 1, but PL 0.15 wt.h. LMK 0.6 parts by weight and an additional 3 parts by weight naphthalene.

The values of the indicators λ and N _FE are shown in the table.

 PRI me R 5. According to example 1, but additionally contains 5 wt.h. naphthalene.

The values of the indicators λ and N _FE are shown in the table.

 It can be seen from the comparison examples that, in the absence of alkyl acrylate (Example 7), the polymer is not processed by extrusion due to an increase in molecular weight, with an increase in the content of alkyl acrylate> 5 wt. (example 8) decreases the quality of GPs. A decrease in the content of dye (coumarin-30) leads to a deterioration in the quality of GPs (example 9), and an increase in its content is impractical (example 10).

 With a decrease in the content of PL and LMC (examples 11, 12), the molecular weight increases, the polymer is not processed by extrusion, an increase in the content of PL and LMC (examples 13, 14) leads to flaring up of the blocks and deterioration of their quality.

 Examples 15-22 illustrate the transcendental values of the polymerization and extrusion modes.

 From example 23 it is seen that the use of another initiator leads to a deterioration in the quality of the GP.

Claims (2)

1. METHOD FOR PRODUCING A POLYMER FIBER-OPTICAL TRANSMITTER by polymerizing a vinyl monomer in the presence of a radical initiator and a chain transmitter to form a core, followed by applying a polyacrylic shell to the core, including a re-emitting additive of 7-diethylamino-3 (1 ′ -methylbenzimide) benzimide the fact that, in order to increase the light output and particle detection efficiency, a mixture of 95 99 wt.% is used as a vinyl monomer. methyl methacrylate and 1 to 5 wt. With ₁ - C ₄ -alkylacrylate, and carry out layer-by-layer polymerization of this mixture in the presence of 0.03 0.07 wt.h. re-emitting additives per 100 wt.h. comonomers with a speed of 1 2 cm / h at 50 70 ^o C, and the shell is applied by coextrusion of the core with polyfluoroacrylate at 190 200 ^o C for 20 30 minutes  2. The method according to claim 1, characterized in that the polymerization is carried out in the presence of 3 to 5 wt.h. naphthalene per 100 parts by weight comonomers.

Images