Method for preparing industrial-scale inverse-vulcanized sulfur-rich polymer by means of temperature programming

Abstract

Disclosed in the present invention is a method for preparing an industrial-scale inverse-vulcanized sulfur-rich polymer by means of temperature programming. The method at least comprises the following steps: step 1, melting a dicyclopentadiene raw material with a certain weight in warm water; step 2, adding precipitated sulfur to the molten dicyclopentadiene, and mixing same until uniform; step 3, heating the mixture to 50°C, and then introducing nitrogen or a rare gas into same; step 4, heating the mixture to 115-120°C; step 5, heating the reaction liquid obtained in step 4 to 140°C, so as to obtain a dark brown pre-polymer; step 6, cooling the dark brown pre-polymer to room temperature, so as to obtain a brown viscous body-prepolymer; step 7, subjecting the brown viscous body-prepolymer to temperature-programmed curing, so as to obtain an inverse-vulcanized sulfur-rich polymer product; and step 8, testing the product by using a differential scanning calorimeter (DSC). The present invention relates to the technical field of chemistry, and in particular relates to a method for preparing an industrial-scale inverse-vulcanized sulfur-rich polymer by means of temperature programming.

Description

A method for preparing industrial-scale reverse vulcanized sulfur-rich polymers by programmed temperature Technical Field

[0001] The present invention relates to the field of chemical technology, and in particular to a method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature elevation. Background Art

[0002] Traditional polymer materials are mostly prepared based on petrochemical products and have the disadvantage of being non-renewable. With the increasing awareness of environmental protection in all walks of life, people's exploration of sustainable and renewable materials has gradually increased. How to use renewable energy or industrial by-products to prepare new polymers with similar or better properties than traditional polymers has become one of the current research hotspots in the field of materials chemistry. Elemental sulfur (S8) is a by-product of the desulfurization reaction that must first be undergone in petroleum refining in the petrochemical industry. Its output is far higher than the demand for sulfur conversion, resulting in about 7 million tons of elemental sulfur being discarded and unable to be processed each year worldwide, causing great pollution to the environment and soil. Therefore, in recent years, domestic and foreign researchers have made preliminary explorations on how to utilize redundant elemental sulfur and tap its potential to prepare chemical materials with good performance.

[0003] The inverse vulcanization method (also known as reverse vulcanization) for preparing sulfur-rich cross-linked polymers was first proposed in 2013 and has garnered widespread attention. This method uses elemental sulfur, a byproduct of the petroleum industry, as a raw material. In the molten state, it cross-links with small organic molecules, resulting in the highly atom-economical preparation of sulfur-rich cross-linked polymers. Such small molecules include, but are not limited to, 1,3-diisopropenylbenzene (DIB), dicyclopentadiene (DCPD), limonene, squalene, perillyl alcohol, and divinylbenzene (DVB). The sulfur-rich polymers prepared using this method are structurally stable and possess unique physical and chemical properties, finding applications in lithium-sulfur batteries, infrared imaging, self-healing, and heavy metal adsorption. However, significant potential remains for the exploration of these new materials' applications. However, the self-acceleration phenomenon severely limits the progress of large-scale industrial research on these materials, increasing the risk of implosion and potentially threatening life. This phenomenon is primarily due to the gradual polymerization of monomers in the reaction system as the reaction proceeds, leading to an increase in the reaction system's viscosity. This further hinders the activity of free radicals in the reaction, and the large amount of accumulated heat cannot be quickly eliminated, which ultimately leads to a significant increase in the polymerization rate. For the inverse sulfur-rich polymerization reaction, at high temperatures, there are a large number of sulfur radicals in the reaction system. If the reaction temperature cannot be effectively controlled, the self-acceleration phenomenon is very likely to occur. In addition, if this reaction system is completed in an open environment, small organic molecules may also be oxidized by oxygen in the air to produce peroxides, thereby triggering the self-oxidation phenomenon. This will lead to the generation of more free radicals, further accelerating the occurrence of the self-accelerating reaction. In response to this problem, existing improved methods include introducing diethyldithiocarbamate metal catalyst catalysis and photocatalysis, but due to their respective process defects, these two methods have failed to produce (in kilograms or tons) sulfur-rich polymers on an industrial scale.

[0004] Summary of the Invention

[0005] To solve the above technical problems, the present invention adopts the following technical solution: a method for preparing an industrial-scale inverse vulcanized sulfur-rich polymer by programmed temperature, comprising at least the following steps:

[0006] Step 1: Take a certain weight of dicyclopentadiene raw material and put it into warm water at 38℃~40℃ and place it until it melts;

[0007] Step 2: Weigh 2 kg of molten dicyclopentadiene in step 1 into a 5 L reactor, then weigh 2 kg of precipitated sulfur (S8) and mix well;

[0008] Step 3: Heat the mixture in step 2 to 50°C, then continuously introduce nitrogen or rare gas to evacuate the oxygen or air in the reactor;

[0009] Step 4: Heat the mixture in step 3 to between 115°C and 120°C to melt it into a transparent reaction solution with a light brown color;

[0010] Step 5: The reaction solution obtained in Step 4 is heated to 140° C. and maintained at this temperature under nitrogen or a rare gas atmosphere for 1 hour, until the color of the reaction solution obtained in Step 4 gradually darkens to an opaque brown reaction solution. The reaction is then continued for 2 hours until the viscosity reaches 100 mPa·s. The temperature is then lowered to below 130° C. to obtain a dark brown prepolymer. The heat source is then removed to terminate the reaction.

[0011] Step 6: Repeat steps 1 to 5 five times to obtain five batches of prepolymer, and then place the five batches of prepolymer into metal trays numbered 1, 2, 3, 4, and 5, respectively;

[0012] Step 7: The five batches of prepolymers obtained in step 6 were respectively subjected to gel permeation chromatography (GPC) to measure the relative molecular weight (number average molecular weight) of the polymers. and weight average molecular weight ) and polymer molecular weight distribution (PDI) were tested, and the number average molecular weight of the five batches was measured. The average value is about 600, and the weight average molecular weight The average value of is about 1000, the average value of PDI is about 1.66, and DSC tests are performed on 5 batches of prepolymers;

[0013] Step 8: Cool the five batches of dark brown prepolymers obtained in step 6 to room temperature to obtain a brown viscous substance - prepolymer sulfur-cyclopentadiene (PreSDCPD);

[0014] Step 9: The five batches of brown viscous prepolymers (pre-SDCPD) obtained in step 8 are subjected to programmed temperature curing to react the unreacted double bonds in the cyclopentadiene. The specific reaction process is as follows: 140°C / 1h+145°C / 1h+150°C / 1h+(170-180°C) / 2h, i.e., heating at 140°C for 1 hour, heating to 145°C and holding for 1 hour, then heating to 150°C and holding for 1 hour, and finally heating to between 170°C and 180°C and holding for 2 hours, thereby obtaining a fully cross-linked polymer (pre-SDCPD).

[0015] Step 10: The five batches of fully cross-linked polymers prepared in step 8 were characterized by differential scanning calorimetry. It was found that after programmed temperature increase, the solid resin had no exothermic peak in the range of >150°C compared to the prepolymer, indicating that the reaction was complete. Furthermore, it was confirmed that fully cross-linked brown solid sulfur-cyclopentadiene was obtained by thermal post-treatment. The glass transition temperature (T) of the fully cross-linked polymer sulfur-cyclopentadiene was g >120℃.

[0016] Preferably, the gas may be one of nitrogen, inert gas, carbon dioxide and other gases.

[0017] Furthermore, in step five, when the viscosity reaches 90-110 mPa·s, the heat source may be removed.

[0018] Furthermore, in step nine, the temperature range of the programmed temperature increase is 130-180°C.

[0019] The beneficial effects of the present invention are as follows: by continuously introducing nitrogen or rare gas, oxygen or air in the reactor is evacuated, thereby preventing the occurrence of self-acceleration and self-oxidation of the reverse vulcanization reaction; judging the reaction degree of the reaction liquid by the viscosity of the prepolymer, thereby effectively avoiding the problems of insufficient reaction and excessive cross-linking of the reaction system; and by programmed temperature increase, effectively controlling the system temperature, accelerating and increasing the system curing efficiency, and thus increasing the production to an industrial scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] FIG1 shows the viscosity-time characteristics of polythioene of the present invention;

[0022] FIG2 is a DSC graph of the first batch of cured polysulfide resin of the present invention;

[0023] FIG3 is a DSC graph of the second batch of cured polysulfide resin of the present invention;

[0024] FIG4 is a DSC graph of the third batch of cured polysulfide resin of the present invention;

[0025] FIG5 is a DSC graph of the fourth batch of cured polysulfide resin of the present invention;

[0026] FIG6 is a DSC graph of the fifth batch of cured polysulfide resin of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The technical solution adopted by the present invention is as follows: a method for preparing an industrial-scale inverse vulcanized sulfur-rich polymer by programmed temperature, comprising at least the following steps:

[0029] Step 1: Take a certain weight of dicyclopentadiene raw material and put it into warm water at 38℃~40℃ and place it until it melts;

[0030] Step 2: Weigh 2 kg of molten dicyclopentadiene in step 1 into a 5 L reactor, then weigh 2 kg of precipitated sulfur (S8) and mix well;

[0031] Step 3: Heat the mixture in step 2 to 50°C, then continuously introduce nitrogen or rare gas to evacuate the oxygen or air in the reactor;

[0032] Step 4: Heat the mixture in step 3 to between 115°C and 120°C to melt it into a transparent reaction solution with a light brown color;

[0033] Step 5: The reaction solution obtained in step 4 is heated to 140° C. and maintained at a constant temperature under nitrogen or a rare gas for 1 hour, causing the reaction solution obtained in step 4 to gradually darken in color and become an opaque brown reaction solution. The reaction is then continued for 2 hours until the viscosity reaches 100 mPa·s, and the temperature is then lowered to below 130° C. to obtain a dark brown prepolymer.

[0034] Step 6: Repeat steps 1 to 5 five times to obtain five batches of prepolymer, and then place the five batches of prepolymer into metal trays numbered 1, 2, 3, 4, and 5, respectively;

[0035] Step 7: The five batches of prepolymers obtained in step 6 were respectively subjected to gel permeation chromatography (GPC) to measure the relative molecular weight (number average molecular weight) of the polymers. and weight average molecular weight ) and polymer molecular weight distribution (PDI) were tested, and the number average molecular weight of the five batches was measured. The average value is about 600, and the weight average molecular weight The average value of is about 1000, the average value of PDI is about 1.66, and DSC tests are performed on 5 batches of prepolymers;

[0036] The following table shows the test results of relative molecular weight and molecular weight distribution of 5 batches of prepolymers

[0037] Step 8: Cool the five batches of dark brown prepolymers obtained in step 6 to room temperature to obtain a brown viscous substance - prepolymer sulfur-cyclopentadiene (PreSDCPD);

[0038] Step 9: The five batches of brown viscous prepolymers (pre-SDCPD) obtained in step 8 are subjected to programmed temperature curing to react the unreacted double bonds in the cyclopentadiene. The specific reaction process is as follows: 140°C / 1h+145°C / 1h+150°C / 1h+(170-180°C) / 2h, i.e., heating at 140°C for 1 hour, heating to 145°C and holding for 1 hour, then heating to 150°C and holding for 1 hour, and finally heating to between 170°C and 180°C and holding for 2 hours, thereby obtaining a fully cross-linked polymer (pre-SDCPD).

[0039] Step 10: The five batches of fully cross-linked polymers prepared in step 8 were characterized by differential scanning calorimetry. It was found that after programmed temperature increase, the solid resin had no exothermic peak in the range of >150°C compared to the prepolymer, indicating that the reaction was complete. Furthermore, it was confirmed that fully cross-linked brown solid sulfur-cyclopentadiene was obtained by thermal post-treatment. The glass transition temperature (T) of the fully cross-linked polymer sulfur-cyclopentadiene was g >120℃.

[0040] The method of the present invention is applicable to a variety of binary reaction systems, such as elemental sulfur and dicyclopentadiene (DCPD) (mixing ratio of 20wt%:80wt%-80wt%:20wt%), elemental sulfur and 1,3-diisopropenylbenzene (DIB) (mixing ratio of 20wt%:80wt%-80wt%:20wt%), elemental sulfur and limonene (limonene) (mixing ratio of 20wt%:80wt%-80wt%:20wt%), elemental sulfur and squalene (squalene) (mixing ratio of 20wt%:80wt%-80wt%:20wt%), elemental sulfur and perillyl alcohol (mixing ratio of 20wt%:80wt%-80wt%:20wt%) and elemental sulfur and divinylbenzene (DVB) (mixing ratio of 20wt%:80wt%-80wt%:20wt%);

[0041] It also includes multi-reaction systems, such as elemental sulfur, dicyclopentadiene (DCPD) and 1,3-diisopropenylbenzene (DIB), as well as the addition of other non-reactive materials such as asphalt, petroleum coke and activated carbon.

[0042] The gas may be one of nitrogen, inert gas, carbon dioxide and other gases.

[0043] In step 5, when the viscosity reaches 90-110 mPa·s, the heat source can be removed.

[0044] In step nine, the temperature range of the programmed temperature rise is 130-180°C.

[0045] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature, characterized in that: Step 1: Put the dicyclopentadiene raw material into warm water at 38℃~40℃ and place it until it is in a molten state; Step 2: Weigh 2 kg of molten dicyclopentadiene in step 1 and put it into a 5L reactor, then weigh 2 kg of precipitated sulfur and mix well; Step 3: Heat the mixture in step 2 to 50°C, then continue to introduce gas to exhaust the oxygen in the reactor; Step 4: Heat the mixture in step 3 to between 115°C and 120°C to melt it into a transparent reaction solution with a light brown color; Step 5: heating the reaction solution obtained in step 4 to 140° C., keeping the temperature constant, and reacting it for 1 hour under the protection of nitrogen or a rare gas, so that the color of the reaction solution obtained in step 4 gradually deepens and becomes an opaque brown reaction solution, and then continuing to react for 2 hours until the viscosity reaches 100 mPa·s, and then reducing the temperature to below 130° C. to obtain a dark brown prepolymer; Step 6: Repeat steps 1 to 5 for 5 times to obtain 5 batches of prepolymers, and then put the 5 batches of prepolymers into metal trays numbered 1, 2, 3, 4, and 5, respectively; Step 7: The five batches of prepolymers obtained in step 6 were tested for relative molecular weight and molecular weight distribution of polymers using gel permeation chromatography. The number average molecular weight of the five batches was The average value is 600, the weight average molecular weight The average value of the polymer molecular weight distribution is 1000, and the average value of the polymer molecular weight distribution is 1.

66. The five batches of prepolymers were tested by differential scanning calorimeter. The polymer relative molecular weight includes the number average molecular weight and weight average molecular weight Step 8: Cooling the five batches of dark brown prepolymers obtained in step 6 to room temperature respectively to obtain a brown viscous body - prepolymer sulfur-cyclopentadiene; Step nine: subjecting the five batches of brown viscous prepolymer sulfur-cyclopentadiene obtained in step eight to programmed temperature curing to react the unreacted double bonds in the cyclopentadiene. The specific reaction process is heating at 140° C. for 1 hour, heating to 145° C. and maintaining for 1 hour, then heating to 150° C. and maintaining for 1 hour, and finally heating to between 170° C. and 180° C. and maintaining for 2 hours, thereby obtaining a completely cross-linked polymer sulfur-cyclopentadiene; Step 10: The five batches of fully cross-linked polymers in step 8 were tested by differential scanning calorimetry. It was found that after programmed temperature increase, the solid resin had no exothermic peak in the range of >150°C compared with the prepolymer, proving that the reaction was complete and that the fully cross-linked brown solid sulfur-cyclopentadiene was obtained by thermal post-treatment. The glass transition temperature T g >120℃.

2. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 1, characterized in that: The dicyclopentadiene is replaced by other polyene compounds, and the polyene compound includes one of 1,3-diisopropenylbenzene, limonene, squalene, perillyl alcohol or divinylbenzene.

3. A method for preparing industrial-scale reverse vulcanized sulfur-rich polymers by programmed temperature rise according to claim 2, characterized in that the mixing ratio of sulfur and polyene compound is 20wt%:80wt%-80wt%:20wt%.

4. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 1, characterized in that: The dicyclopentadiene is replaced by a mixture of polyene compounds, and the mixture includes multiple species of dicyclopentadiene, 1,3-diisopropenylbenzene, limonene, squalene, perillyl alcohol or divinylbenzene.

5. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 4, characterized in that: The mixing ratio of sulfur and the mixture is 20wt%:80wt%-80wt%:20wt%.

6. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 4, characterized in that: Other non-reactive materials are added, including asphalt, petroleum coke and activated carbon.

7. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 1, characterized in that: The gas may be one of nitrogen, an inert gas and carbon dioxide.

8. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 1, characterized in that: In step 5, when the viscosity reaches 90-110 mPa·s, the heat source can be removed.

9. The method for preparing an industrial-scale reverse-vulcanized sulfur-rich polymer by programmed temperature rise according to claim 1, characterized in that: In step nine, the temperature range of the programmed temperature rise is 130-180°C.

Images