A method for improving the dispersibility and thermal stability of insoluble sulphur

Abstract

This invention discloses a method for improving the dispersibility and thermal stability of insoluble sulfur, belonging to the field of sulfur processing and production technology. The technical solution includes: 1) mixing naphthenic oil, a dispersant, a stabilizer, and a compatibilizer to obtain a mixture; the dispersant is one or more of dithiodibenzothiazole, zinc stearate, dioctyl phthalate, polyethylene glycol monolaurate, oleyl alcohol, and fatty alcohol polyoxyethylene ether; the compatibilizer is one or more of ethylene propylene diene monomer (EPDM), EVA resin, and liquid butadiene rubber; 2) mixing the mixture with unfilled insoluble sulfur semi-finished product and performing an oil-filling treatment to obtain insoluble sulfur. The method provided by this invention not only produces insoluble sulfur with good dispersibility and thermal stability, but also has a simple and easy-to-implement process, which is beneficial for improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of sulfur processing and production technology, and particularly relates to a method for improving the dispersibility and thermal stability of insoluble sulfur. Background Technology

[0002] Insoluble sulfur is an amorphous polymer of sulfur, characterized by its insolubility in common solvents such as carbon disulfide. It is primarily used as a rubber vulcanizing agent in the tire industry, including for tire treads and sidewalls. Its advantages include preventing blooming (surface whitening) and improving the heat resistance, abrasion resistance, and aging resistance of rubber products.

[0003] The synthesis of insoluble sulfur is divided into batch and continuous processes. The basic production process can be divided into the following steps: sulfur melting / gasification heating, rapid cooling, solidification, extraction, filtration, drying, sieving, and oil filling. The batch process is costly and cumbersome, and the synthesized sample is a large, blocky particle. In the continuous process, the sulfur raw material can be recycled, resulting in low cost. The synthesized sample is a micron-sized spherical fine powder (usually with a particle size of 10-20 μm). However, the product prepared by the continuous method has a large specific surface area and high surface energy, which easily forms hard agglomerates, resulting in poor dispersion performance in rubber and difficulty in separation in the matrix. The dispersibility of the product affects the mechanical and abrasion resistance properties of rubber products. The main factors affecting the dispersibility of insoluble sulfur include: particle size, particle shape, particle uniformity, the compatibility of particle surface polarity with the matrix (such as rubber), oil filling amount, and mixing process. Insoluble sulfur is a linear amorphous polymer of sulfur (degree of polymerization 200-3000). It is thermodynamically unstable and easily undergoes depolymerization at high temperatures, transforming into cyclic soluble sulfur (S8). Poor thermal stability of the product directly leads to problems such as rubber vulcanization failure, product performance degradation, and reduced production efficiency. Therefore, dispersibility and thermal stability are key indicators for evaluating the performance of insoluble sulfur.

[0004] To improve product dispersibility, patent CN103303873A adds sodium tripolyphosphate, zinc stearate, silica, anti-scorching agent, and lignin sulfonate during sulfur melting, followed by stirring and heating. However, this method of adding dispersants during sulfur melting and heating is prone to solvent washing during later extraction, affecting the dispersant's effectiveness. Patent CN103303874A adds alum during sulfur melting and heating to improve product dispersibility, but alum significantly increases the ash content, causing the ash content to exceed the national standard (which stipulates an ash content below 0.3%). Patent CN102732064A adds water-soluble polymers such as amylose, amylopectin, modified starch, and cyclodextrin to insoluble sulfur, dissolving them in water and then coating them with powder to improve dispersibility. However, water-soluble polymers often have polar groups such as hydroxyl groups, while insoluble sulfur is a non-polar product, making it difficult for the water-soluble polymers to effectively coat the product, thus affecting the dispersion effect. Therefore, a simple and efficient method is needed to improve the dispersibility of insoluble sulfur products. Summary of the Invention

[0005] To address the shortcomings of existing technologies, a method is proposed to improve the dispersibility and thermal stability of insoluble sulfur. This method not only ensures that the prepared insoluble sulfur has good dispersibility and thermal stability, but also features a simple and easy-to-implement process, which is beneficial for improving production efficiency.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the dispersibility and thermal stability of insoluble sulfur includes the following steps:

[0008] 1) Mix naphthenic oil, dispersant, stabilizer and compatibilizer to obtain a mixture;

[0009] The dispersant is one or more of the following: dithiodibenzothiazole, zinc stearate, dioctyl phthalate, polyethylene glycol monolaurate, oleyl alcohol, and fatty alcohol polyoxyethylene ether.

[0010] The compatibilizer is one or more of EPDM rubber, EVA resin, and liquid butadiene rubber;

[0011] The stabilizer includes one or more of methylstyrene, pinene, and hydrobromic acid;

[0012] The amount of naphthenic oil added is 18%-25% of the mass of the unfilled insoluble sulfur semi-finished product;

[0013] The amount of the dispersant added is 0.1%-5% of the mass of the unfilled, oil-insoluble sulfur semi-finished product;

[0014] The amount of stabilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product;

[0015] The amount of the compatibilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product;

[0016] 2) The mixture is mixed with unfilled insoluble sulfur semi-finished product and subjected to oil filling treatment to obtain insoluble sulfur.

[0017] Preferably, in step 1), an antistatic agent is added before mixing, and the antistatic agent includes one or more of sodium dodecylbenzenesulfonate and glyceryl monostearate.

[0018] Preferably, the amount of dispersant added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

[0019] Preferably, the amount of stabilizer added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

[0020] Preferably, the amount of the compatibilizer added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

[0021] Preferably, the amount of antistatic agent added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

[0022] Preferably, the un-oil-added insoluble sulfur semi-finished product is prepared by the following method:

[0023] a. The raw material liquid sulfur is vaporized at high temperature, and the resulting vaporization product is subjected to CS2 rapid cooling synthesis at 60°C to obtain an insoluble sulfur preproduct.

[0024] b. The insoluble sulfur preproduct is sequentially subjected to aging, refining, centrifugation, drying, pulverizing, and sieving to obtain un-oil-added insoluble sulfur.

[0025] Preferably, after the oil filling treatment in step 2), the particles are further graded and screened; the particle size of the sieved particles is 30-150μm.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The present invention provides a method for improving the dispersibility and thermal stability of insoluble sulfur. Using unextended insoluble sulfur as raw material, a dispersant, compatibilizer, antistatic agent, and stabilizer are added to naphthenic oil. This mixed naphthenic oil is then added to the unextended insoluble sulfur raw material for oil extrusion. During the oil extrusion process, the dispersant and compatibilizer are added. The dispersant material fills the micropores of the insoluble sulfur, and the compatibilizer makes the product have a polar surface, which is highly beneficial for dispersion in polar rubber. This results in the prepared insoluble sulfur exhibiting excellent dispersibility and thermal stability.

[0028] Meanwhile, the one-pot oil filling process avoids the need for subsequent separate addition of dispersants, stabilizers, etc., shortens the process time, reduces resource and energy consumption, is simple and easy to implement, and helps improve production efficiency. Attached Figure Description

[0029] Figure 1 The image shown is a DSC characterization diagram of the product prepared in Example 1 of this invention.

[0030] Figure 2 The image shown is a scanning electron microscope image of the product prepared in Example 1 of this invention.

[0031] Figure 3 Micrograph of the compounded film prepared using the product prepared in Example 1 of the present invention;

[0032] Figure 4 The image shown is a DSC characterization diagram of the product prepared in Example 2 of this invention.

[0033] Figure 5 The image shown is a scanning electron microscope image of the product prepared in Example 2 of this invention.

[0034] Figure 6 Micrograph of the compounded film prepared using the product prepared in Example 2 of the present invention;

[0035] Figure 7 The image shown is a DSC characterization diagram of the product prepared in Example 3 of this invention.

[0036] Figure 8 The image shown is a scanning electron microscope image of the product prepared in Example 3 of this invention.

[0037] Figure 9 Micrograph of the compounded film prepared using the product prepared in Example 3 of the present invention;

[0038] Figure 10 The image shown is a DSC characterization diagram of the product prepared in Example 4 of this invention.

[0039] Figure 11 The image shown is a scanning electron microscope image of the product prepared in Example 4 of this invention.

[0040] Figure 12 Micrograph of the compounded film prepared using the product prepared in Example 4 of this invention;

[0041] Figure 13 The image shows the DSC characterization of the product prepared in Comparative Example 1 of this invention.

[0042] Figure 14 A scanning electron microscope image of the product prepared in Comparative Example 1 of this invention;

[0043] Figure 15 Micrograph of the compounded film prepared using the product prepared in Comparative Example 1 of the present invention.

[0044] Figure 16 This is a DSC characterization diagram of the product prepared in Comparative Example 2 of the present invention;

[0045] Figure 17 This is a scanning electron microscope image of the product prepared in Comparative Example 2 of the present invention;

[0046] Figure 18 Micrograph of the compounded film prepared using the product prepared in Comparative Example 2 of the present invention.

[0047] Figure 19 The image shows the DSC characterization of the product prepared in Comparative Example 3 of this invention.

[0048] Figure 20 This is a scanning electron microscope image of the product prepared in Comparative Example 3 of the present invention;

[0049] Figure 21 The image shows a micrograph of the compounded film prepared using the product prepared in Comparative Example 3 of this invention. Detailed Implementation

[0050] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0051] A method for improving the dispersibility and thermal stability of insoluble sulfur includes the following steps:

[0052] 1) Mix naphthenic oil, dispersant, stabilizer and compatibilizer to obtain a mixture;

[0053] The dispersant is one or more of the following: dithiodibenzothiazole, zinc stearate, dioctyl phthalate, polyethylene glycol monolaurate, oleyl alcohol, and fatty alcohol polyoxyethylene ether.

[0054] The stabilizer is one or more of methylstyrene, pinene, and hydrobromic acid;

[0055] The stabilizer includes one or more of methylstyrene, pinene, and hydrobromic acid;

[0056] The amount of naphthenic oil added is 18%-25% of the mass of the unfilled insoluble sulfur semi-finished product;

[0057] The amount of the dispersant added is 0.1%-5% of the mass of the unfilled, oil-insoluble sulfur semi-finished product;

[0058] The amount of stabilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product;

[0059] The amount of the compatibilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product;

[0060] 2) The mixture is mixed with unfilled insoluble sulfur semi-finished product and subjected to oil filling treatment to obtain insoluble sulfur.

[0061] This invention mixes naphthenic oil, a dispersant, a stabilizer, and a compatibilizer to obtain a mixture. In this invention, the amount of naphthenic oil added is preferably 18%-25% of the mass of the unfilled, oil-insoluble sulfur semi-finished product. In this invention, the dispersant is one or more of dithiodibenzothiazole, zinc stearate, dioctyl phthalate, polyethylene glycol monolaurate, oleyl alcohol, and fatty alcohol polyoxyethylene ether. In this invention, the amount of dispersant added is 0.1%-5% of the mass of the unfilled, oil-insoluble sulfur semi-finished product, preferably 0.3-3%, more preferably 0.5%-2%. In this invention, by using the above-mentioned dispersant material to fill the micropores of the insoluble sulfur, the agglomeration force between filler particles can be reduced, allowing the filler to form a uniform dispersed phase in the rubber compound, rather than locally agglomerated "lumps," directly improving the overall physical properties of the product.

[0062] In this invention, the compatibilizer is one or more of ethylene propylene diene monomer (EPDM) rubber, EVA resin, and liquid butadiene rubber. In this invention, the amount of compatibilizer added is 0.1%-5% of the mass of the unextended oil-insoluble sulfur semi-finished product, preferably 0.3-3%, and more preferably 0.5-2%. In this invention, using the above-mentioned compatibilizer can make the product have a polar surface, improving the bonding degree between the product and the rubber molecular chain.

[0063] In this invention, the stabilizer includes one or more of methylstyrene, pinene, and hydrobromic acid. In this invention, the use of the above stabilizer can stabilize the free radicals at both ends of insoluble sulfur, maintain the long-chain structure, and preserve high thermal stability. In this invention, the amount of stabilizer added is 0.1%-5% of the mass of the unextended insoluble sulfur semi-finished product, preferably 0.3-3%, and more preferably 0.5-2%.

[0064] In this invention, dispersants, stabilizers, and compatibilizers are directly mixed with naphthenic oil. The dispersants and compatibilizers are added during the oil-filling process of insoluble sulfur. The dispersant material fills the micropores of the insoluble sulfur, while the compatibilizer makes the product have a polar surface, which is highly beneficial for dispersion in polar rubber. The addition of stabilizers stabilizes the free radicals at both ends of the insoluble sulfur, maintaining a long-chain structure and high thermal stability. Furthermore, the one-pot oil-filling process avoids the need for subsequent separate additions of dispersants and stabilizers, shortening the process time, reducing resource and energy consumption, and is simple and easy to implement, thus improving production efficiency.

[0065] In this invention, an antistatic agent is preferably added before mixing. The antistatic agent preferably includes one or more of sodium dodecylbenzenesulfonate and glyceryl monostearate. In this invention, the amount of antistatic agent added is 0.1%-5% of the mass of the unextended, oil-insoluble sulfur semi-finished product, preferably 0.3-3%, and more preferably 0.5-2%. In this invention, the addition of the antistatic agent can prevent powder agglomeration and ensure particle size uniformity.

[0066] After obtaining the mixture, the present invention further involves mixing the mixture with unextended insoluble sulfur semi-finished product and performing an oil-extending treatment to obtain insoluble sulfur. In the present invention, the unextended insoluble sulfur semi-finished product is preferably prepared by the following method:

[0067] a. The raw material liquid sulfur is vaporized at high temperature, and the resulting vaporization product is subjected to CS2 rapid cooling synthesis at 60°C to obtain an insoluble sulfur preproduct.

[0068] b. The insoluble sulfur preproduct is sequentially subjected to aging, refining, centrifugation, drying, pulverizing, and sieving to obtain un-oil-added insoluble sulfur.

[0069] The unextracted insoluble sulfur powder used in the embodiments and comparative examples of this invention adopts the following process: the raw material liquid sulfur is vaporized at high temperature (>500℃) and synthesized by rapid cooling with CS2 at 60℃ to obtain an insoluble sulfur preproduct; the obtained insoluble sulfur preproduct is aged at 55℃ for 10h, refined at 50℃ for 5h, centrifuged at 600rpm / min, dried at 50℃ for 2h, pulverized and passed through a 100-mesh sieve to obtain the product.

[0070] In this invention, after oil filling, it is preferable to further perform grading and sieving; the particle size of the sieved particles is 30-150 μm.

[0071] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0072] Example 1

[0073] Add 25 parts of 4006 naphthenic oil, 1 part of dithiodibenzothiazole, 0.5 parts of zinc stearate, 0.5 parts of liquid cis-butadiene rubber, 0.5 parts of sodium dodecylbenzenesulfonate, and 1 part of methylstyrene additive to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oil extrusion of the product, obtaining the final insoluble sulfur product.

[0074] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 1 and 2 As shown.

[0075] Dispersibility test: 500g of masticated masterbatch (with added carbon black), 20g of oil-extended insoluble sulfur powder, 4g of N-tert-butyl-2-benzothiazole sulfenamide, and 20g of adhesive RA-65 additive were placed in an internal mixer and heated to 105℃. The mixture was then continuously mixed at this temperature for 100 seconds. Afterwards, it was subjected to roller milling at 70℃, cut twice, and then sheeted. The sheeted material was then examined under a microscope (see attached microscope image). Figure 3 (As shown) The number of undispersed sulfur beans (sulfur particles with a diameter greater than 1 mm) was measured, and the number, size, and uniformity of the sulfur beans were used to represent the quality of dispersibility.

[0076] Depend on Figure 1 It can be seen that the DSC peak temperature is 133.4℃, from Figure 2 As can be seen from the scanning electron microscope image, the particles are uniformly distributed without obvious aggregation. Figure 3 It can be seen that no sulfur granules were found in the compounded rubber sheet, indicating that the insoluble sulfur sample in this example has good thermal stability and is well dispersed in rubber.

[0077] Example 2

[0078] Add 18 parts of 4006 naphthenic oil, 1 part of oleyl alcohol, 2 parts of EVA resin, 0.1 parts of glyceryl monostearate, and 2 parts of pinene to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the mixture to 100 parts of unextended insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oil extrusion process, obtaining the final insoluble sulfur product.

[0079] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 4 and 5 As shown, the specific microscope images taken during the dispersibility test are as follows. Figure 6 As shown, the specific dispersion test method is the same as in Example 1.

[0080] Depend on Figure 4 It can be seen that the peak temperature of DSC is 128.5℃. Figure 5 As can be seen from the scanning electron microscope image, the particles are uniformly distributed without obvious aggregation. Figure 6 It can be seen that no sulfur beans were found in the compounded rubber sheets, indicating that the mixture was well dispersed in the rubber.

[0081] Example 3

[0082] Add 25 parts of 4006 naphthenic oil, 0.5 parts of dioctyl phthalate, 0.5 parts of fatty alcohol polyoxyethylene ether, 0.1 parts of ethylene propylene diene monomer (EPDM) rubber, 0.5 parts of glyceryl monostearate, and 0.1 parts of hydrobromic acid to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oil extrusion process, obtaining the final insoluble sulfur product.

[0083] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 7 and 8 As shown, the specific microscope images taken during the dispersibility test are as follows. Figure 9 As shown, the specific dispersion test method is the same as in Example 1.

[0084] Depend on Figure 7 It can be seen that the peak temperature of DSC is 128.5℃. Figure 8 As can be seen from the scanning electron microscope image, the particles are uniformly distributed without obvious aggregation. Figure 9 It can be seen that no sulfur beans were found in the compounded rubber sheets, indicating that the mixture was well dispersed in the rubber.

[0085] Example 4

[0086] Add 25 parts of 4006 naphthenic oil, 0.2 parts of polyethylene glycol monolaurate, 1 part of liquid cis-butadiene rubber, 2 parts of sodium dodecylbenzenesulfonate, and 1 part of methylstyrene additive to a mixer. Mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended insoluble sulfur powder and mix thoroughly at 30 rpm for 30 minutes to complete the oil extrusion process, obtaining the final insoluble sulfur product.

[0087] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 10 and 11 As shown, the specific microscope images taken during the dispersibility test are as follows. Figure 12 As shown, the specific dispersion test method is the same as in Example 1.

[0088] Depend on Figure 10 It can be seen that the peak temperature of DSC is 128℃. Figure 11 As can be seen from the scanning electron microscope image, the particles are uniformly distributed without obvious aggregation. Figure 12 It can be seen that no sulfur beans were found in the compounded rubber sheets, indicating that the mixture was well dispersed in the rubber.

[0089] Comparative Example 1

[0090] Add 25 parts of 4006 naphthenic oil, 0.5 parts of liquid cis-butadiene rubber, 0.5 parts of sodium dodecylbenzenesulfonate, and 1 part of methylstyrene additive to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oiling of the product.

[0091] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 13 and 14 As shown, the specific microscope images taken during the dispersibility test are as follows. Figure 15 As shown, the specific dispersion test method is the same as in Example 1. Figure 13 It can be seen that the DSC peak temperature is 126.7℃, from Figure 14 It can be seen that there are obvious large particle aggregates in the scanning electron microscope images, which are caused by Figure 15 It can be seen that there are many sulfur beads in the compounded rubber sheets. The sulfur beads are of different sizes, indicating that the insoluble sulfur sample in this comparative ratio is poorly dispersed in the rubber. The dispersant plays a crucial role in the dispersibility.

[0092] Comparative Example 2

[0093] Add 25 parts of 4006 naphthenic oil, 1 part of dithiodibenzothiazole, 0.5 parts of zinc stearate, 0.5 parts of liquid cis-butadiene rubber, and 0.5 parts of sodium dodecylbenzene sulfonate to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended, insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oiling of the product.

[0094] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 16 and 17 As shown, the specific microscope images taken during the dispersibility test are as follows. Figure 18 As shown, the specific dispersion test method is the same as in Example 1. Figure 16 It can be seen that the peak temperature of DSC is 125℃, from Figure 17 As can be seen, the particles are evenly distributed in the scanning electron microscope image, with a small number of small particles agglomerated. Figure 18 It can be seen that there are fewer sulfur beads in the compounded rubber sheet, and the sulfur bean particle size is small, indicating that the insoluble sulfur sample in this comparative ratio is relatively well dispersed in the rubber, but has poor thermal stability. The stabilizer plays a crucial role in stability.

[0095] Comparative Example 3

[0096] Add 25 parts of 4006 naphthenic oil, 1 part of dithiodibenzothiazole, 0.5 parts of zinc stearate, 0.5 parts of sodium dodecylbenzenesulfonate, and 1 part of methylstyrene additive to a mixer. Stir and mix at 30 rpm for 10 minutes to obtain a mixture. Add the above mixture to 100 parts of unextended insoluble sulfur powder and stir thoroughly at 30 rpm for 30 minutes to complete the oil extrusion process, obtaining the final insoluble sulfur product.

[0097] The obtained insoluble sulfur final product was characterized for thermal stability and microstructure by DSC and scanning electron microscopy, specifically as follows: Figure 19 and 20 As shown. The specific microscope image taken during the dispersibility test is shown below. Figure 21 As shown, the specific dispersibility test method is the same as in Example 1. It can be seen that the DSC peak temperature is 126.8℃, and large particle agglomeration is observed in the scanning electron microscope image. A large number of sulfur beads appear in the compounded rubber sheet, and the sulfur bean particle size is relatively large, indicating that the insoluble sulfur sample in this comparative example is poorly dispersed in the rubber, and the compatibilizer plays a crucial role in dispersibility.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the dispersibility and thermal stability of insoluble sulfur, characterized in that, Includes the following steps: 1) Mix naphthenic oil, dispersant, stabilizer and compatibilizer to obtain a mixture; The dispersant is one or more of the following: dithiodibenzothiazole, zinc stearate, dioctyl phthalate, polyethylene glycol monolaurate, oleyl alcohol, and fatty alcohol polyoxyethylene ether. The compatibilizer is one or more of EPDM rubber, EVA resin, and liquid butadiene rubber; The stabilizer includes one or more of methylstyrene, pinene, and hydrobromic acid; The amount of naphthenic oil added is 18%-25% of the mass of the unfilled insoluble sulfur semi-finished product; The amount of the dispersant added is 0.1%-5% of the mass of the unfilled, oil-insoluble sulfur semi-finished product; The amount of stabilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product; The amount of the compatibilizer added is 0.1%-5% of the mass of the unfilled oil-insoluble sulfur semi-finished product; 2) The mixture is mixed with unfilled insoluble sulfur semi-finished product and subjected to oil filling treatment to obtain insoluble sulfur; In step 1), an antistatic agent is added before mixing. The antistatic agent includes one or more of sodium dodecylbenzenesulfonate and glyceryl monostearate. The amount of antistatic agent added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

2. The method for improving the dispersibility and thermal stability of insoluble sulfur according to claim 1, characterized in that, The amount of dispersant added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

3. The method for improving the dispersibility and thermal stability of insoluble sulfur according to claim 1, characterized in that, The amount of stabilizer added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

4. The method for improving the dispersibility and thermal stability of insoluble sulfur according to claim 1, characterized in that, The amount of the compatibilizer added is 0.3%-3% of the mass of the unfilled oil-insoluble sulfur semi-finished product.

5. The method for improving the dispersibility and thermal stability of insoluble sulfur according to claim 1, characterized in that, The un-oil-added insoluble sulfur semi-finished product was prepared by the following method: a. The raw material liquid sulfur is vaporized at high temperature, and the resulting vaporization product is subjected to CS2 rapid cooling synthesis at 60°C to obtain an insoluble sulfur preproduct. b. The insoluble sulfur preproduct is sequentially subjected to aging, refining, centrifugation, drying, pulverizing, and sieving to obtain un-oil-added insoluble sulfur.

6. The method for improving the dispersibility and thermal stability of insoluble sulfur according to claim 1, characterized in that, After oil filling in step 2), the particles are further graded and screened; the particle size of the sieved particles is 30-150 μm.

Images