CN114315545B - Crystallization process for photoinitiator production and product thereof - Google Patents
Crystallization process for photoinitiator production and product thereof Download PDFInfo
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- 238000003756 stirring Methods 0.000 claims description 28
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- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 8
- 238000004321 preservation Methods 0.000 claims description 8
- QNODIIQQMGDSEF-UHFFFAOYSA-N (1-hydroxycyclohexyl)-phenylmethanone Chemical compound C=1C=CC=CC=1C(=O)C1(O)CCCCC1 QNODIIQQMGDSEF-UHFFFAOYSA-N 0.000 claims description 6
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- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- UKRQMDIFLKHCRO-UHFFFAOYSA-N 2,4,6-trimethylbenzoyl chloride Chemical compound CC1=CC(C)=C(C(Cl)=O)C(C)=C1 UKRQMDIFLKHCRO-UHFFFAOYSA-N 0.000 description 1
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- JCRCPEDXAHDCAJ-UHFFFAOYSA-N ethoxy(diphenyl)phosphane Chemical compound C=1C=CC=CC=1P(OCC)C1=CC=CC=C1 JCRCPEDXAHDCAJ-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to a crystallization process for photoinitiator production and a product thereof, wherein the crystallization process comprises three steps of cooling crystallization, heating crystallization and uniform cooling crystallization; the crystallization process adjusts the crystal size and morphology obtained by crystallization through cooling crystallization and heating crystallization steps, and then controls the uniform cooling crystallization at a specific cooling rate, so that the photoinitiator crystals with concentrated particle size distribution are obtained, and compared with the photoinitiator crystals with flaky and fragile microstructures obtained by the traditional direct cooling crystallization process, the photoinitiator crystals obtained by the crystallization process fully grow in the third dimension direction, have the advantages of massive microstructure, high thickness, high hardness, difficult agglomeration and agglomeration in the storage process, and obviously improve the storage stability.
Description
Technical Field
The invention belongs to the field of production of photoinitiators, and relates to a crystallization process for producing photoinitiators and a product thereof.
Background
The photoinitiator is a compound which can absorb energy with a certain wavelength in an ultraviolet light region or a visible light region to generate free radicals, cations and the like so as to initiate the polymerization, crosslinking and curing of monomers; the preparation process of the photoinitiator generally comprises the steps of molecular synthesis of the photoinitiator, solvent evaporation and dissolution and crystallization; wherein, the dissolution and crystallization process is used as a key step of photoinitiator production, which has important influence on the crystal structure and performance of the photoinitiator product;
the existing photoinitiator dissolving and crystallizing process generally adopts the steps of heating and dissolving the photoinitiator, and then directly cooling and crystallizing at low temperature to obtain photoinitiator crystal slurry, namely directly cooling and crystallizing through low-temperature chilled water or cold brine; the temperature control of the cooling process is less, and the obtained crystal has the problems of low hardness, easy breakage and poor storage performance;
CN103333206a discloses a preparation method of a TPO photoinitiator, which comprises taking diphenyl ethoxyphosphine as a main raw material, reacting with toluene and 2,4, 6-trimethylbenzoyl chloride together, heating to melt, cooling for crystallization, filtering, and drying to obtain a product; CN211226974U is a purifying device for photoinitiator, which is capable of cooling the photoinitiator solution to below zero by adopting brine to cool the solution, and rapidly cooling and crystallizing the solution; the above processes all adopt direct cooling crystallization, lack of control on the cooling process, and the obtained crystals have the corresponding defects.
Therefore, it is still of great importance to develop a crystallization process for photoinitiator production that can effectively enhance the properties of the crystal structure.
Disclosure of Invention
The invention aims to provide a crystallization process for photoinitiator production and a product thereof, wherein the crystallization process comprises three steps of cooling crystallization, heating crystallization and uniform cooling crystallization; the crystallization process adjusts the crystal size and morphology obtained by crystallization through cooling crystallization and heating crystallization steps, and then controls the uniform cooling crystallization at a specific cooling rate, so that the photoinitiator crystals with concentrated particle size distribution are obtained, and compared with the photoinitiator crystals with flaky and fragile microstructures obtained by the traditional direct cooling crystallization process, the photoinitiator crystals obtained by the crystallization process fully grow in the third dimension direction, have the advantages of massive microstructure, high thickness, high hardness, difficult agglomeration and agglomeration in the storage process, and obviously improve the storage stability.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a crystallization process for photoinitiator production, the crystallization process comprising the steps of:
(1) Cooling and crystallizing: cooling the photoinitiator solution to a crystallization temperature;
(2) Heating and crystallizing: heating and crystallizing the solution cooled and crystallized in the step (1) at a preset heating rate;
(3) And (5) cooling and crystallizing at a constant speed: and (3) carrying out uniform cooling crystallization on the solution obtained by heating crystallization in the step (2) to obtain crystal slurry containing photoinitiator crystals.
The traditional cooling crystallization process of the photoinitiator generally comprises the steps of placing a photoinitiator solution in a cooling crystallizer, and then directly introducing chilled water for cooling crystallization to obtain a photoinitiator crystal; the photoinitiator crystals obtained by the operation mode have wide particle size distribution range, are mostly of a two-dimensional lamellar structure, have poor hardness and brittleness, have poor subsequent storage performance, are easy to agglomerate, and influence the service performance of the photoinitiator; the crystallization process comprises three steps of cooling crystallization, heating crystallization and uniform cooling crystallization; the initial crystal nucleus is generated through a cooling crystallization process, the size and the morphology of the initial crystal nucleus are effectively adjusted through a specific heating crystallization operation, the subsequent full growth of the crystal in the third dimension direction is facilitated, and then the uniform cooling crystallization operation is performed at a specific cooling rate, so that the crystal nucleus growth rate is improved, and the obtained crystal is massive, high in hardness, not fragile and concentrated in particle size distribution.
The particle size distribution of the photoinitiator crystals obtained by the invention is in the range of 10-30 meshes, and the ratio of the particle size distribution can reach more than 65%.
In addition, the research shows that the step (3) adopts uniform cooling crystallization, and compared with the non-uniform cooling crystallization process, the obtained crystal has larger granularity, higher hardness, more sufficient growth in the third dimension direction, better storage performance, quick crystal growth rate and short crystal growth time after uniform cooling crystallization.
The crystal slurry containing the photoinitiator crystals obtained by the uniform cooling crystallization is filtered and dried to obtain a photoinitiator crystal product, and the crystal structure of the crystal slurry has the characteristics of high hardness and difficult breakage and agglomeration of crystals in the storage process, so that the storage stability is obviously improved.
Preferably, the cooling rate of the cooling process of step (1) is selected from 10 to 20 ℃/h, such as 11, 12, 13, 14, 15, 16, 17, 18 or 19 ℃/h etc., preferably 14 to 18 ℃/h, such as 14.5, 15, 15.5, 16, 16.5, 17 or 17.5 ℃/h etc.
In the step (1), the cooling rate is controlled in the above range in the process of cooling and crystallization, which is favorable for rapidly obtaining crystal nuclei, saving the operation time of the crystallization process, and the size and performance of the crystal nuclei are convenient for the subsequent operation of Wen Huajing, so that the structural performance of the finally obtained photoinitiator crystal is improved, and the photoinitiated crystal which is massive, thick, hard, not fragile and excellent in storage performance is obtained.
Preferably, the preset heating rate in step (2) is selected from 1 to 5 ℃/h, such as 2 ℃/h, 3 ℃/h or 4 ℃/h, and the like, preferably 3 to 4 ℃/h, such as 3.5 ℃/h, and the like.
The temperature rising rate is controlled in the range, the size and the shape of the initial crystal nucleus can be effectively adjusted, the full growth of the subsequent crystal nucleus in the third dimension direction is facilitated, and the concentration of the crystal particle size distribution is increased.
Preferably, the temperature increase value in step (2) is selected from 1℃to 5℃such as 1.5℃and 2℃and 2.5℃and 3℃and 3.5℃and 4℃and 4.5℃and the like, and more preferably 2℃to 4℃such as 2.5℃and 3℃and 3.5℃and the like.
The temperature rising temperature is controlled in the range in the process of rising temperature crystallization, so that excessive melting of crystal nuclei is avoided, the initial crystal nucleus size and morphology are adjusted, and the subsequent crystal is fully grown.
Preferably, the heating medium used in the process of heating and crystallizing in the step (2) is selected from hot water or low-pressure steam.
Preferably, the cooling rate in step (3) is selected from 2.5 to 6 ℃/h, e.g. 3 ℃/h, 3.5 ℃/h, 4 ℃/h, 4.5 ℃/h, 5 ℃/h or 5.5 ℃/h etc., preferably 3.5 to 5 ℃/h, e.g. 4 ℃/h or 4.5 ℃/h etc.
The step (3) adopts uniform cooling crystallization, which is favorable for obtaining photoinitiator crystals with concentrated particle size distribution, and the obtained crystals are in a block shape, fully grow in the third dimension direction, and have large thickness, large hardness and difficult breakage; in addition, the cooling rate is controlled to be selected from 3.5 ℃/h to 5 ℃/h, the grain size of the obtained crystal is within the range of 10-30 meshes, the ratio of the grain size of the obtained crystal can reach more than 75wt%, the subsequent storage is convenient, and the subsequent use performance is better.
Preferably, the final temperature of the reduced temperature crystallization in step (3) is 8℃to 18℃such as 9℃10℃11℃12℃13℃14℃15℃16℃17℃or the like.
Preferably, the step (3) further comprises crystal growth after the uniform cooling crystallization.
Preferably, the crystal growing method comprises keeping constant temperature at the end temperature of the uniform cooling crystallization in the step (3).
Preferably, the crystal growing process is accompanied by stirring, and the stirring speed is preferably 10 rpm-100 rpm; for example, 20rpm, 30rpm, 40rpm, 50rpm, 60rpm, 70rpm, 80rpm, 90rpm, etc., and more preferably 20rpm to 50rpm.
The crystal growing process is accompanied by stirring, and the stirring speed is adopted to keep crystals in the crystal slurry in a moving state.
Preferably, the time for growing the crystals is 0 to 2 hours, for example, 0 hours, 0.1 hours, 0.3 hours, 0.5 hours, 0.7 hours, 0.9 hours, 1 hour, or 1.5 hours, etc., and more preferably 1 to 10 minutes, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, or 9 minutes, etc.
Preferably, the cooling and crystallizing in the step (1) further comprises pre-cooling the photoinitiator solution.
Preferably, the pre-cooling rate is 3 ℃/h to 8 ℃/h, such as 4 ℃/h, 5 ℃/h, 6 ℃/h, 7 ℃/h, or the like.
Preferably, the initial temperature of the photoinitiator solution in step (1) is between 35℃and 45℃such as 36℃37℃38℃39℃40℃41℃42℃43℃44℃and the like.
The initial temperature refers to the initial temperature at which the crystals are cooled and crystallized in the step (1).
Preferably, the concentration of the photoinitiator solution in step (1) is 30 to 50wt%; for example, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt% or 49wt%, etc., preferably 35wt% to 45wt%.
The concentration of the photoinitiator in the photoinitiator solution for cooling crystallization is in the range, so that crystal particles with more concentrated particle size distribution range can be obtained, and the obtained crystal particles with more particle sizes are distributed in the range of 10-30 meshes.
Preferably, the photoinitiator in the photoinitiator solution in step (1) is a photoinitiator 184, and the formula is as follows:
preferably, the solvent of the photoinitiator solution in step (1) is selected from petroleum ether.
Preferably, stirring is carried out during the steps (1), (2) and (3); the stirring speed is preferably 150 to 350rpm, for example, 160rpm, 170rpm, 180rpm, 190rpm, 200rpm, 210rpm, 220rpm, 230rpm, 240rpm, 250rpm, 260rpm, 270rpm, 280rpm, 290rpm, 300rpm, 310rpm, 320rpm, 330rpm or 340rpm, etc., and more preferably 200 to 250rpm.
The stirring rate is controlled within the range, so that the crystal nucleus suspension state in the crystallizer is good, the crystal nucleus suspension state is uniformly distributed, and crystals with good structural performance and concentrated particle size distribution are obtained; the stirring speed is preferably 200 rpm-250 rpm, and the stirring speed is too high, which is unfavorable for the growth of crystals, and the granularity of the obtained crystals can be reduced.
Preferably, the processes of the step (1), the step (2) and the step (3) are performed in a cooling crystallization kettle, the cooling crystallization kettle comprises a kettle body for containing a photoinitiator solution, a heat preservation sleeve is wrapped outside the kettle body, and a heating coil and a cooling coil which are alternately arranged are arranged in the heat preservation sleeve.
The cooling crystallization process is carried out in the cooling crystallization kettle, the outer wall of the cooling crystallization kettle is wrapped with the heat preservation sleeve, and the heat preservation sleeve is internally provided with the heating coil and the cooling coil, so that compared with a crystallizer only comprising the cooling coil, the cooling crystallization kettle is convenient to control the temperature rising crystallization process, is convenient to control the temperature rising and the temperature reducing rate, and further ensures a good crystallization effect in the uniform-speed temperature reducing crystallization process. Compared with the method for realizing the temperature control by simply adjusting the flow of the cooling medium in the cooling coil, the temperature control method provided by the invention has the advantage of better temperature control effect.
Preferably, hot water is circulated through the heating coil.
Preferably, chilled water is circulated within the cooling coil.
Preferably, the pipeline inlets and outlets of the heating coil and the cooling water coil are respectively provided with a valve capable of adjusting flow.
The valve is arranged here to facilitate control of the flow of the cooling medium and the heating medium.
Preferably, a stirring paddle is arranged in the kettle body.
Preferably, a temperature sensor is arranged in the cooling crystallization kettle.
Preferably, the cooling crystallization kettle further comprises a controller, wherein the controller can receive and process signals of the temperature sensor and can control the opening sizes and the opening and closing states of the valves of the heating pipeline and the cooling pipeline.
The cooling crystallization kettle can control the cooling rate and the heating rate through the arrangement, and is convenient for realizing the cooling crystallization process.
Preferably, the cooling crystallization kettle is also provided with a photoinitiator solution inlet and a crystal slurry outlet.
As a preferred technical scheme of the invention, the crystallization process comprises the following steps:
(a) Preparing a solution: the photoinitiator 184 is dissolved in a solvent to obtain a photoinitiator solution with the temperature of 50-70 ℃ and the concentration of 35-45 wt%;
(b) Precooling: transferring the photoinitiator solution obtained in the step (a) into a cooling crystallization kettle; opening a cooling coil or a cooling coil and a heating coil, and controlling the cooling rate of 3-8 ℃ per hour to precool to 35-45 ℃;
(c) Cooling and crystallizing: controlling the solution obtained in the step (b) to be cooled to 25-30 ℃ at a cooling rate of 14-18 ℃ per hour, and cooling and crystallizing;
(d) Heating and crystallizing: controlling the solution cooled and crystallized in the step (c) to heat at a preset heating rate of 3-4 ℃ per hour, wherein the heating value of the heating is selected from 2-4 ℃;
(e) And (5) cooling and crystallizing at a constant speed: controlling the solution obtained by heating and crystallizing in the step (d) to uniformly cool and crystallize at a final temperature of 8-18 ℃ at a cooling rate of 3.5-5 ℃/h;
(f) Growing the crystal: controlling the temperature of the product obtained by uniform cooling crystallization in the step (e) to be constant at the end temperature value of the product for 0-2 h, so as to obtain crystal slurry containing photoinitiator crystals;
wherein, stirring is carried out in the process of step (b) -step (e), and the stirring speed is 200 rpm-250 rpm;
and (f) stirring in the crystal growing process, wherein the stirring speed is 20-50 rpm.
In a second aspect, the present invention provides a photoinitiator crystal obtained by the crystallization process according to the first aspect, wherein the morphology of the photoinitiator crystal is in a block shape.
Preferably, the mass ratio of the particle size of the photoinitiator crystals is between 10 mesh and 30 mesh is greater than or equal to 65%, such as 66%, 67%, 68%, 69%, 70%, 71%, 73%, 75%, 77%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96% or 98%, etc., preferably greater than or equal to 75%.
Compared with the prior art, the invention has the following beneficial effects:
(1) The crystallization process for photoinitiator production comprises the steps of cooling crystallization, heating crystallization and uniform cooling crystallization, and through the combination of the steps, the third dimension (thickness) direction of the crystal is fully grown, so that a blocky crystal is obtained, the obtained crystal has the characteristics of high hardness and uneasy breakage, the problem that the flaky crystal obtained by the traditional crystallization process is easy to break, agglomerate and agglomerate in the storage process is solved, and the storage performance of the photoinitiator crystal is improved;
(2) The crystallization process for photoinitiator production has the advantage that the grain size distribution range of the obtained crystals is more concentrated.
Drawings
FIG. 1 is a microscopic view of the crystals of the photoinitiator obtained in example 1 and comparative example 1 of the present invention;
FIG. 2 is a graph showing the particle size distribution of the photoinitiator crystals obtained in example 1 and example 4 of the present invention;
FIG. 3 is a particle size distribution diagram of the photoinitiator crystals described in comparative example 1 of the present invention;
FIG. 4 is a graph showing the particle size distribution of the photoinitiator crystals obtained in comparative examples 2 and 3 according to the present invention;
FIG. 5 is an XRD pattern of the photoinitiator crystals obtained in example 1 and comparative example 1 of the present invention;
FIG. 6 is a schematic structural diagram of a cooling crystallization kettle according to the present invention;
1-kettle body, 2-insulation sleeve, 20-heating coil, 21-cooling coil, 22-inlet valve, 23-outlet valve, 3-stirring paddle, 4-temperature sensor inserting port, 5-controller, 6-photoinitiator solution adding port and 7-crystal slurry discharging port.
Detailed Description
The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
The raw materials used in the examples and comparative examples were selected from the following compositions:
the photoinitiator was photoinitiator 184 from the new material stock company of the Tianjin ju-dado;
the solvent is selected from petroleum ether with a boiling range of 60-90 ℃;
example 1
The present embodiment provides a crystallization process for photoinitiator production, the crystallization process comprising the steps of:
(a) Preparing a solution: the photoinitiator 184 was dissolved in petroleum ether to give a photoinitiator solution at a temperature of 50 ℃ and a concentration of 43.5 wt%;
(b) Precooling: transferring the photoinitiator solution obtained in the step (a) into a cooling crystallization kettle, and controlling the pre-cooling to 35 ℃ at a cooling rate of 5 ℃/h;
(c) Cooling and crystallizing: controlling the solution obtained in the step (b) to be cooled to 27 ℃ at a cooling rate of 16 ℃/h;
(d) Heating and crystallizing: controlling the solution cooled and crystallized in the step (c) to be heated at a preset heating rate of 3 ℃/h, wherein the heating value of the heating is 3 ℃;
(e) And (5) cooling and crystallizing at a constant speed: controlling the solution obtained by heating and crystallizing in the step (d) to uniformly cool and crystallize at a final temperature of 10 ℃ at a cooling rate of 4.5 ℃/h to obtain crystal slurry containing photoinitiator crystals;
the above process was carried out in a cooling crystallization kettle using a propeller type stirring paddle, and the stirring rate was controlled to 200rpm during steps (b) to (e).
The slurry containing the photoinitiator crystals obtained in example 1 was filtered, washed and dried to obtain photoinitiator crystals.
Example 2
The present example provides a crystallization process for photoinitiator production; the crystallization process is different from the crystallization process in example 1 only in that no pre-cooling process is included, namely, the cooling crystallization process directly cools the photoinitiator solution from 50 ℃ to 27 ℃ at a cooling rate of 16 ℃/h, and other parameters and conditions are exactly the same as those in example 1;
example 3
The present example provides a crystallization process for photoinitiator production; the crystallization process is different from the crystallization process in the embodiment 1 only in that a crystal growing step is added after the step (e), namely the temperature of a product obtained by uniform cooling crystallization in the step (e) is controlled to be constant at the end temperature value for 15min, and crystal slurry containing photoinitiator crystals is obtained, and other parameters and conditions are identical to those in the embodiment 1.
Example 4
The difference between this example and example 1 is that the cooling rate of the uniform cooling crystallization in step (e) is 3.5 ℃/h, and other parameters and conditions are exactly the same as those in example 1.
Example 5
The difference between this example and example 1 is that the cooling rate of the uniform cooling crystallization in step (e) is 2.5 ℃/h, and other parameters and conditions are exactly the same as those in example 1.
Example 6
The difference between this example and example 1 is that the cooling rate of the uniform cooling crystallization in step (e) is 6 ℃/h, and other parameters and conditions are exactly the same as those in example 1.
Example 7
The present embodiment provides a crystallization process for photoinitiator production, the crystallization process comprising the steps of:
(a) Preparing a solution: dissolving a photoinitiator in a solvent to obtain a photoinitiator solution with the temperature of 60 ℃ and the concentration of 45 wt%;
(b) Precooling: transferring the photoinitiator solution obtained in the step (a) into a cooling crystallization kettle; controlling the pre-cooling to 38 ℃ at a cooling rate of 7 ℃/h;
(c) Cooling and crystallizing: controlling the solution obtained in the step (b) to be cooled to 27.5 ℃ at a cooling rate of 17 ℃/h;
(d) Heating and crystallizing: controlling the solution cooled and crystallized in the step (c) to be heated at a preset heating rate of 4 ℃/h, wherein the heating value of the heating is 3.5 ℃;
(e) And (5) cooling and crystallizing at a constant speed: controlling the solution obtained by heating and crystallizing in the step (d) to uniformly cool and crystallize at a cooling rate of 4.5 ℃/h until the end temperature is 15 ℃ to obtain crystal slurry containing photoinitiator crystals;
other parameters and conditions were exactly the same as in example 1.
Comparative example 1
The comparative example adopts the crystallization process of the traditional factory, namely, the photoinitiator solution in the step (a) is placed in a cooling crystallization kettle, then 0 ℃ frozen water is introduced for cooling crystallization until the solution temperature is 10 ℃, and then the crystallization treatment is carried out for 1.5 hours, so as to obtain the photoinitiator crystal slurry;
other parameters and conditions were exactly the same as in example 1.
Comparative example 2
The comparative example differs from example 1 only in that no constant cooling is used in step (e), and the cooling rate follows the following curve equation; the cooling speed is fast and then slow;
T＝4.19exp(-t/2.11)+15.55exp(-t/264.04)+4.19exp(-t/25.26)+8.57，R2＝0.9999；
wherein T is temperature, DEG C, T is time, min;
other parameters and conditions were exactly the same as in example 1.
Comparative example 3
The comparative example differs from example 1 only in that no constant cooling is used in step (e), and the cooling rate follows the following curve equation; the cooling rate is slow and then fast;
t= 43.14exp (T/263.76) -11.97exp (T/166.68) -13.85exp (T/166.64) +15.14, r2=0.9999; wherein T is temperature, DEG C, T is time, min;
other parameters and conditions were exactly the same as in example 1.
Comparative example 4
The comparative example differs from example 1 only in that the temperature-rising crystallization process is not included, and other parameters and conditions are exactly the same as those in example 1.
The photoinitiator crystals obtained in the above examples and comparative examples were tested for particle size distribution, especially for mass fractions having particle size distributions between 10 and 30 mesh; the test results are shown in table 1;
TABLE 1
| The mass ratio of the granularity between 10 and 30 meshes is wt% | |
| Example 1 | 79.98 |
| Example 2 | 76.15 |
| Example 3 | 80.12 |
| Example 4 | 76.58 |
| Example 5 | 67.75 |
| Example 6 | 65.24 |
| Example 7 | 77.25 |
| Comparative example 1 | 29.50 |
| Comparative example 2 | 24.56 |
| Comparative example 3 | 26.17 |
| Comparative example 4 | 40.25 |
The data in the above table were tested by sieving.
As can be seen from the above Table 1, the particle size distribution of the photoinitiator crystals obtained by the crystallization process of the invention is more than 65% by mass between 10 and 30 meshes, and the corresponding mass ratios in comparative examples 1 to 4 are all less than 50%;
in addition, as can be seen from comparative examples 1, 2, the pre-cooling process is added, which is advantageous for improving the concentration of the particle size distribution of the crystals; as can be seen from comparative examples 1 and 3, the crystal growth in the crystal slurry obtained by the crystallization process of the present invention is substantially balanced, and the grain size is limited to be raised during the crystal growth process; as can be seen from comparative examples 1 and 4-6, the uniform cooling rate in step (e) of the present invention has a large influence on the particle size distribution of the product crystals, and the cooling rate is further preferably 3.5 to 4.5 ℃/h; as can be seen from comparative examples 1 and 2-3, the crystallization process of the photoinitiator adopts uniform cooling crystallization, and compared with the cooling operation mode adopted in comparative examples 2-3, the proportion of the obtained crystals with the particle size distribution in the range of 10-30 meshes is obviously higher, so that the uniform cooling at a proper temperature is illustrated to be beneficial to the growth of the crystal particle size; as can be seen from comparative examples 1 and 4, the proportion of the grain size distribution of the crystals obtained in the range of 10 to 30 mesh was significantly reduced without employing the temperature rising crystallization operation during the experiment.
Performance test:
polarizing microscope test: the crystals obtained in example 1 and comparative example 1 were subjected to a polarizing microscope to test the crystal morphology thereof; as shown in fig. 1, the photoinitiator crystals of comparative example 1 were significantly smaller in the third dimension (thickness) direction, which was a plate-like structure; the photoinitiator crystals obtained in example 1 were sufficiently grown in the third dimension direction and had a block structure; the difference of the crystal morphology enables the crystal obtained in the embodiment 1 to have enough hardness, not to be fragile, not to be easy to agglomerate in the storage process, not to influence the subsequent use, and is beneficial to improving the subsequent use effect.
The crystal size distribution is tested in the following two ways; the first is to test by a granularity tester; the test results in figures 2, 3 and 4 were obtained as described above; the second method is screening, the photoinitiator crystals are screened through screens with the mesh number of 10 meshes and 30 meshes, the mass of the crystal particles which are obtained through screening and are positioned between 10 meshes and 30 meshes is weighed and recorded, the mass ratio of the crystal particles is calculated, and the data in table 1 adopt the second mode.
In the process of testing by adopting the second testing method, the photoinitiator crystals obtained in the embodiments 1-7 have higher hardness, are not fragile and have good stability in the screening process; in the screening process of the flaky photoinitiator crystals in the comparative example 1, the crystals are obviously broken and have low hardness; therefore, compared with the flaky photoinitiator crystals in comparative example 1, the crystals obtained by the crystallization process have higher stability, are not easy to break up and agglomerate in the storage process, and further ensure the subsequent use performance.
The particle size distribution diagrams of the photoinitiator crystals obtained in examples 1 and 4 of the present invention are shown in fig. 2, and it can be seen that the particle size distribution of the photoinitiator crystals obtained by the crystallization process of the present invention is concentrated; the particle size distribution curve of the photoinitiator crystals in comparative example 1 of the present invention is shown in fig. 3, and it can be seen that the particle size distribution range is wider; the particle size distribution curves of the photoinitiator crystals in comparative examples 2 and 3 of the present invention are shown in fig. 4, and it can be seen that the crystal sizes are smaller.
The XRD curves of the photoinitiator crystals in example 1 of the present invention and comparative example 1 are shown in FIG. 5, and it can be seen that the crystal phase structure of the crystals is similar.
The structural schematic diagram of the cooling crystallization kettle is shown in fig. 6, and comprises: a kettle body 1 for containing photoinitiator solution, wherein the kettle body is externally wrapped with a heat preservation sleeve 2, and a heating coil 20 and a cooling coil 21 which are alternately arranged are arranged in the heat preservation sleeve; hot water is circulated through the heating coil 20; chilled water flows through the cooling coil 21; the inlet and outlet of the heating coil 20 and the cooling coil 21 are respectively provided with an inlet valve 22 and an outlet valve 23 which can adjust the flow; the stirring paddle 3 is arranged in the kettle body and is driven to rotate by a motor.
The kettle body is provided with a temperature sensor inserting port 4, and the temperature sensor is inserted below the liquid level in the kettle body through the temperature sensor inserting port, so that the temperature of the liquid in the kettle body is monitored in real time;
the cooling crystallization kettle further comprises a controller 5, wherein the controller 5 can receive and process signals of the temperature sensor and can control the opening sizes and the opening and closing states of the inlet valve 22 and the outlet valve 23; thereby realizing the real-time control of the temperature in the cooling crystallization process and the program temperature control process.
The kettle body is provided with a photoinitiator solution adding port 6 and a crystal slurry discharging port 7, the crystal slurry discharging port is positioned at the bottom of the kettle body, and the photoinitiator solution adding port is positioned at the top of the kettle body.
The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.
Claims (31)
1. A crystallization process for photoinitiator production, characterized in that the crystallization process comprises the steps of:
(1) Cooling and crystallizing: cooling the photoinitiator solution to a crystallization temperature;
(2) Heating and crystallizing: heating and crystallizing the solution cooled and crystallized in the step (1) at a preset heating rate;
(3) And (5) cooling and crystallizing at a constant speed: carrying out uniform cooling crystallization on the solution obtained by heating crystallization in the step (2) to obtain crystal slurry containing photoinitiator crystals;
the cooling rate in the cooling process in the step (1) is selected from 10-20 ℃/h;
the preset heating rate in the step (2) is selected from 1-5 ℃/h;
the temperature rise value in the step (2) is selected from 1-5 ℃.
2. The crystallization process for photoinitiator production according to claim 1, wherein the cooling rate of the cooling process of step (1) is selected from 14 ℃/h to 18 ℃/h.
3. The crystallization process for photoinitiator production according to claim 1, wherein the preset heating rate of step (2) is selected from 3 ℃/h to 4 ℃/h.
4. A crystallization process for photoinitiator production according to claim 3 wherein the elevated temperature in step (2) is selected from 2 ℃ to 4 ℃.
5. The crystallization process for photoinitiator production according to claim 1, wherein the heating medium used in the process of raising the temperature to crystallize in step (2) is selected from hot water or low pressure steam.
6. The crystallization process for photoinitiator production according to claim 1, wherein the cooling rate in step (3) is selected from 2.5 ℃/h to 6 ℃/h.
7. The crystallization process for photoinitiator production according to claim 1, wherein the cooling rate in step (3) is selected from 3.5 ℃/h to 5 ℃/h.
8. The crystallization process for photoinitiator production according to claim 1, wherein the end point temperature of the reduced crystallization of step (3) is 8 ℃ to 18 ℃.
9. The crystallization process for photoinitiator production according to claim 1, wherein the uniform temperature reduction crystallization in step (3) further comprises crystal growth.
10. The crystallization process for photoinitiator production according to claim 9, wherein the method of seeding comprises maintaining a constant temperature at the end point temperature of the constant temperature-decreasing crystallization of step (3).
11. The crystallization process for photoinitiator production according to claim 10, wherein the crystal growing process is accompanied by stirring at a rate of 10rpm to 100rpm.
12. The crystallization process for photoinitiator production according to claim 11, wherein the stirring rate is 20rpm to 50rpm.
13. The crystallization process for photoinitiator production according to claim 9, wherein the time for crystal growth is 0 to 2 hours.
14. The crystallization process for photoinitiator production according to claim 1, wherein the cooling of step (1) further comprises pre-cooling the photoinitiator solution prior to crystallization.
15. The crystallization process for photoinitiator production according to claim 14, wherein the pre-chilled cooling rate is 3 ℃/h to 8 ℃/h.
16. The crystallization process for photoinitiator production according to claim 1, wherein the initial temperature of the photoinitiator solution in step (1) is between 35 ℃ and 45 ℃.
17. The crystallization process for photoinitiator production according to claim 1, wherein the concentration of the photoinitiator solution in step (1) is 30 to 50wt%.
18. The crystallization process for photoinitiator production according to claim 17, wherein the concentration of the photoinitiator solution in step (1) is between 35% and 45% by weight.
19. The crystallization process for photoinitiator production according to claim 1, wherein the photoinitiator in the photoinitiator solution in step (1) is photoinitiator 184.
20. The crystallization process for photoinitiator production according to claim 1, wherein the solvent of the photoinitiator solution in step (1) is selected from petroleum ether.
21. The crystallization process for photoinitiator production according to claim 1, wherein stirring is accompanied during step (1), step (2) and step (3); the stirring speed is 150 rpm-350 rpm.
22. The crystallization process for photoinitiator production according to claim 21, wherein the stirring rate is 200rpm to 250rpm.
23. The crystallization process for photoinitiator production according to claim 1, wherein the processes of step (1), step (2) and step (3) are performed in a cooling crystallization kettle comprising a kettle body for containing a photoinitiator solution, wherein a heat preservation sleeve is wrapped outside the kettle body, and a heating coil and a cooling coil are alternately arranged in the heat preservation sleeve.
24. The crystallization process for photoinitiator production according to claim 23, wherein hot water is circulated through the heating coil.
25. The crystallization process for photoinitiator production according to claim 23, wherein chilled water is circulated within the cooling coil.
26. The crystallization process for photoinitiator production according to claim 23, wherein the heating coil and the cooling water coil are each provided with a valve for adjusting the flow rate.
27. The crystallization process for photoinitiator production according to claim 23, wherein the kettle body is internally provided with a stirring paddle.
28. The crystallization process for photoinitiator production according to claim 23, wherein the cooling crystallization kettle is built-in with a temperature sensor.
29. The crystallization process for photoinitiator production according to claim 23, wherein the cooling crystallization kettle further comprises a controller, the controller being capable of receiving and processing signals from the temperature sensor and controlling the opening and closing of the valve openings of the heating line and the cooling line.
30. The crystallization process for photoinitiator production according to claim 23, wherein the cooling crystallization kettle is further provided with a photoinitiator solution inlet and a crystal slurry outlet.
31. The crystallization process for photoinitiator production according to claim 1, wherein the crystallization process comprises the steps of:
(a) Preparing a solution: the photoinitiator 184 is dissolved in a solvent to obtain a photoinitiator solution with the temperature of 50-70 ℃ and the concentration of 35-45 wt%;
(b) Precooling: transferring the photoinitiator solution obtained in the step (a) into a cooling crystallization kettle; opening a cooling coil or a cooling coil and a heating coil, and controlling the cooling rate of 3-8 ℃ per hour to precool to 35-45 ℃;
(c) Cooling and crystallizing: controlling the solution obtained in the step (b) to be cooled to 25-30 ℃ at a cooling rate of 14-18 ℃ per hour, and cooling and crystallizing;
(d) Heating and crystallizing: controlling the solution cooled and crystallized in the step (c) to heat at a preset heating rate of 3-4 ℃ per hour, wherein the heating value of the heating is selected from 2-4 ℃;
(e) And (5) cooling and crystallizing at a constant speed: controlling the solution obtained by heating and crystallizing in the step (d) to uniformly cool and crystallize at a final temperature of 8-18 ℃ at a cooling rate of 3.5-5 ℃/h;
(f) Growing the crystal: controlling the temperature of the product obtained by uniform cooling crystallization in the step (e) to be constant at the end temperature value of the product for 0-2 h, so as to obtain crystal slurry containing photoinitiator crystals;
wherein, stirring is carried out in the process of step (b) -step (e), and the stirring speed is 200 rpm-250 rpm;
and (f) stirring in the crystal growing process, wherein the stirring speed is 20-50 rpm.
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