Preparation method of lignin-silica composite material

Abstract

This invention belongs to the field of rubber modification material synthesis technology, and particularly relates to a method for preparing a lignin-silica composite material. Addressing the problem of uneven lignin dispersion in non-polar rubber in existing technologies, this invention provides a method for preparing a lignin-silica composite material, comprising: mixing lignin, silica, and water until homogeneous; adding the mixture to a ball mill jar for ball milling to obtain a preliminary mixture; mixing anhydrous ethanol and a silicon source, and hydrolyzing with acid for 15-45 minutes to obtain a reaction solution; adding the reaction solution to the preliminary mixture, and continuing ball milling for 30-90 minutes; and spray drying after ball milling to obtain the lignin-silica composite material. This invention reacts the numerous methoxy, phenolic hydroxyl, and carboxyl groups present in the lignin structure with the hydroxyl groups in silica, and then further grafting modification using a silicon source, effectively improving the dispersibility of lignin in non-polar rubber.

Description

Technical Field

[0001] This invention belongs to the field of rubber modified material synthesis technology, and particularly relates to a method for preparing a lignin-silica composite material. Background Technology

[0002] Lignin is a natural polymer compound with a three-dimensional network structure. Its abundance in nature is second only to cellulose. Although the pulp and paper industry and biorefining industry separate more than 50 million tons of industrial lignin byproducts from plants annually, the current effective utilization rate of industrial lignin is less than 5%. Lignin molecules possess a rigid aromatic structure, which allows it to be used as a reinforcing agent in rubber. However, in non-polar rubbers such as natural rubber and EPDM rubber, the abundance of phenolic hydroxyl groups on the lignin surface makes it difficult to disperse uniformly, leading to internal agglomeration and severely affecting various polymer properties. Therefore, there is an urgent need to provide a method to improve the dispersibility of lignin in non-polar rubbers.

[0003] For example, a Chinese invention patent application [Application No.: 202110848612.6] discloses a lignin-silica composite material and its preparation method and application. This invention involves a first reaction of aminated lignin with a sodium metasilicate solution, a second reaction of adding ammonium chloride solution, and a third reaction of adjusting the pH to 1-5 to obtain the lignin-silica composite material. The solvent for the sodium metasilicate solution is an ethanol solution, and the mass-to-volume ratio of sodium metasilicate to ethanol solution is 1 g: 20-60 mL.

[0004] Although that invention application also ultimately produced a lignin-silica composite material, its purpose was to improve the dispersibility of silica, an inorganic nanoparticle, as can be seen from the fact that the technical solution of that invention application included a large proportion of silica. Therefore, the technical concept of that invention application is completely different from that of this application. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a method for preparing lignin-silica composite materials that can improve the dispersibility of lignin in non-polar rubber.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions:

[0007] A method for preparing a lignin-silica composite material includes the following steps:

[0008] Step 1: Mix lignin, silica, and water thoroughly, then add the mixture to a ball mill jar for ball milling to obtain a preliminary mixture;

[0009] Step 2: Mix anhydrous ethanol and silicon source, add acid and hydrolyze for 15-45 minutes to obtain reaction solution;

[0010] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 30-90 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0011] In the above-mentioned method for preparing lignin-silica composite material, in step one, the mass ratio of lignin, silica, and water is 25:25:50.

[0012] In the above-mentioned method for preparing lignin-silica composite material, in step one, zirconium oxide is added during ball milling, and the ball milling time is 1-3 hours.

[0013] In the above-mentioned method for preparing lignin-silica composite material, in step two, the silicon source is a mixture of γ-aminopropyltriethoxysilane and 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane.

[0014] In the above-mentioned method for preparing lignin-silica composite material, in step two, the mass ratio of anhydrous ethanol, γ-aminopropyltriethoxysilane, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane is 20:2:1.

[0015] In the above-mentioned method for preparing lignin-silica composite material, the acid added in step two is dilute hydrochloric acid, and the pH value of hydrolysis is 3-5.

[0016] In the above-mentioned method for preparing lignin-silica composite material, in step three, the mass ratio of the initial mixture to the reaction solution is 100:23.

[0017] The above-mentioned method for preparing lignin-silica composite material also includes the step of applying the lignin-silica composite material to rubber.

[0018] In the above-mentioned method for preparing lignin-silica composite materials, the operation steps are as follows:

[0019] The lignin-silica composite material, natural rubber, carbon black, indirect zinc oxide, and stearic acid were sequentially added to a torque rheometer and mixed for 20 minutes at 48 r / min and 100°C to obtain a compound. The compound was then added to a two-roll mill, and sulfur and 2,2'-dithiodibenzothiazole were added sequentially. The mixture was then mixed for 10 minutes at 60°C. The two-roll mill was used with the minimum roll spacing (less than 1 mm) and the rolls were rolled in a triangular pattern 5 times. The spacing was then adjusted to 2 mm to remove air bubbles before sheeting. Finally, the sheet was cured by hot pressing at 150°C for 20 minutes using a flat vulcanizing machine to obtain the finished rubber product.

[0020] In the above-mentioned method for preparing lignin-silica composite material, the mass ratio of the lignin-silica composite material, natural rubber, carbon black, indirect zinc oxide and stearic acid is 15:100:35:5:2.5.

[0021] Compared with existing technologies, the advantages of this invention are:

[0022] 1. This invention reacts numerous methoxy, phenolic hydroxyl, and carboxyl groups in the lignin structure with the hydroxyl groups in silica, and then uses a silicon source for further grafting modification, which effectively improves the dispersibility of lignin in non-polar rubber.

[0023] 2. The raw materials for this invention are readily available, the operation is simple, and the production cost is low, making it suitable for large-scale promotion and use. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments.

[0025] Example 1

[0026] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0027] Step 1: Mix 25 parts by weight of lignin, 25 parts by weight of silica and 50 parts by weight of water until homogeneous, add the mixture to a ball mill jar containing zirconium oxide and ball mill for 1 hour to obtain a preliminary mixture.

[0028] Step 2: Mix 20 parts by weight of anhydrous ethanol, 2 parts by weight of γ-aminopropyltriethoxysilane and 1 part by weight of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 3, and hydrolyze for 15 min to obtain the reaction solution.

[0029] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 30 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0030] Example 2

[0031] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0032] Step 1: Mix 25 parts by weight of lignin, 25 parts by weight of silica and 50 parts by weight of water until homogeneous, then add the mixture to a ball mill jar containing zirconium oxide and ball mill for 3 hours to obtain a preliminary mixture.

[0033] Step 2: Mix 20 parts by mass of anhydrous ethanol, 2 parts by mass of γ-aminopropyltriethoxysilane and 1 part by mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 5, and hydrolyze for 45 min to obtain the reaction solution.

[0034] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 90 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0035] Example 3

[0036] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0037] Step 1: Mix 25 parts by weight of lignin, 25 parts by weight of silica and 50 parts by weight of water until homogeneous, add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0038] Step 2: Mix 20 parts by mass of anhydrous ethanol, 2 parts by mass of γ-aminopropyltriethoxysilane and 1 part by mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0039] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0040] Example 4

[0041] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0042] Step 1: Mix 20 parts by weight of lignin, 30 parts by weight of silica and 50 parts by weight of water until homogeneous, then add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0043] Step 2: Mix 20 parts by mass of anhydrous ethanol, 2 parts by mass of γ-aminopropyltriethoxysilane and 1 part by mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0044] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0045] Example 5

[0046] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0047] Step 1: Mix 25 parts by weight of lignin, 50 parts by weight of silica and 25 parts by weight of water until homogeneous, add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0048] Step 2: Mix 20 parts by mass of anhydrous ethanol, 2 parts by mass of γ-aminopropyltriethoxysilane and 1 part by mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0049] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0050] Example 6

[0051] This embodiment provides a method for preparing a lignin-silica composite material, including the following steps:

[0052] Step 1: Mix 30 parts by weight of lignin, 20 parts by weight of silica and 50 parts by weight of water until homogeneous, add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0053] Step 2: Mix 20 parts by mass of anhydrous ethanol, 2 parts by mass of γ-aminopropyltriethoxysilane and 1 part by mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0054] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0055] Example 7

[0056] This embodiment provides a method for applying lignin-silica composite materials to rubber, including the following steps:

[0057] 15 parts by weight of lignin-silica composite material, 100 parts by weight of natural rubber, 35 parts by weight of carbon black, 5 parts by weight of indirect zinc oxide, and 2.5 parts by weight of stearic acid were sequentially added to a torque rheometer and mixed for 20 minutes at 48 r / min and 100°C to obtain a compound. The compound was then added to a two-roll mill, and 3 parts by weight of sulfur and 0.5 parts by weight of 2,2'-dithiodibenzothiazole were added sequentially. The mixture was then mixed for 10 minutes at 60°C with the two-roll mill extrusion rolls at the minimum thin-pass setting. The mixture was then rolled in a triangular pattern 5 times, and the gap was adjusted to 2 mm to remove air bubbles before sheeting. Finally, the sheet was hot-pressed at 150°C for 20 minutes using a flat vulcanizing machine to obtain the finished rubber product.

[0058] Comparative Example 1

[0059] This comparative example provides a method for preparing a lignin-silica composite material, comprising the following steps:

[0060] Step 1: Mix 25 parts by weight of lignin, 25 parts by weight of silica and 50 parts by weight of water until homogeneous, add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0061] Step 2: Mix 20 parts by weight of anhydrous ethanol and 3 parts by weight of sodium metasilicate, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 minutes to obtain the reaction solution;

[0062] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0063] Comparative Example 2

[0064] This comparative example provides a method for preparing a lignin-silica composite material, comprising the following steps:

[0065] Step 1: Mix 20 parts by weight of lignin, 30 parts by weight of silica and 50 parts by weight of water until homogeneous, then add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0066] Step 2: Mix 20 parts by weight of anhydrous ethanol and 3 parts by weight of γ-aminopropyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution;

[0067] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0068] Comparative Example 3

[0069] This comparative example provides a method for preparing a lignin-silica composite material, comprising the following steps:

[0070] Step 1: Mix 20 parts by weight of lignin, 30 parts by weight of silica and 50 parts by weight of water until homogeneous, then add the mixture to a ball mill jar containing zirconium oxide and ball mill for 2 hours to obtain a preliminary mixture.

[0071] Step 2: Mix 20 parts by mass of anhydrous ethanol and 3 parts by mass of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0072] Step 3: Add the reaction solution obtained in Step 2 to the initial mixture obtained in Step 1, and continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain the lignin-silica composite material.

[0073] Comparative Example 4

[0074] This comparative example provides a method for preparing a lignin-silica composite material, comprising the following steps:

[0075] Step 1: Mix 20 parts by weight of anhydrous ethanol, 2 parts by weight of γ-aminopropyltriethoxysilane and 1 part by weight of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, add dilute hydrochloric acid to adjust the pH to 4, and hydrolyze for 30 min to obtain the reaction solution.

[0076] Step 2: Add lignin and silica to a ball mill jar containing zirconium oxide and ball mill for 2 hours. Then add 20 parts by mass of lignin, 30 parts by mass of silica and 50 parts by mass of water to the reaction solution.

[0077] Step 3: Continue ball milling for 60 minutes. After ball milling, a composite material solution is obtained. Spray dry to obtain lignin-silica composite material.

[0078] Application Example 1

[0079] A piece of natural rubber was taken and cut into 5 equal parts. The contact angle between the composite material solution and the natural rubber in Example 3 and Comparative Examples 1-4 was measured using a TH-SDJ80 contact angle measuring instrument produced by Shandong Tianhong Intelligent Technology Co., Ltd., and recorded as test groups 1-5 respectively. The results are shown in the table below:

[0080] experimental group Static contact angle (degrees) Test Group 1 40 Test Group 2 110 Test Group 3 86 Test group 4 72 Test group 5 122

[0081] Results Analysis: As shown in the table above, the lignin-silica composite material prepared by the method provided in this invention has the best compatibility with natural rubber, meaning it is easier to disperse in natural rubber. Changing the composition of the silicon source or altering the reaction sequence will significantly affect the dispersion performance of the final lignin-silica composite material.

[0082] Application Example 2

[0083] Rubber product 1 was prepared by using the lignin-silica composite material obtained in Example 3 and the method described in Example 7;

[0084] Rubber product 2 was prepared by using the lignin-silica composite material obtained in Comparative Example 1 and the method described in Example 7;

[0085] Rubber product 3 was prepared by using the lignin-silica composite material obtained in Comparative Example 2 and the method described in Example 7;

[0086] Rubber product 4 was prepared by using the lignin-silica composite material obtained in Comparative Example 3 and the method described in Example 7;

[0087] Rubber product 5 was prepared by using the lignin-silica composite material obtained in Comparative Example 4 and the method described in Example 7;

[0088] The relevant performance data of rubber products 1-5 were tested respectively, and the results are shown in the table below:

[0089]

[0090] Results Analysis: By comparing the relevant performance data of rubber products 1-5, it can be seen that the rubber products prepared by this invention also have the best comprehensive performance, thus achieving the expected purpose of this invention.

[0091] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing a lignin-silica composite material, characterized by, The preparation method comprises the following steps: Step 1: mixing lignin, white carbon black and water uniformly, and adding into a ball mill tank to perform ball milling to obtain a preliminary mixture; Step 2: mixing anhydrous ethanol and a silicon source, adding acid to hydrolyze for 15-45 min to obtain a reaction solution; Step 3: adding the reaction solution obtained in step 2 into the preliminary mixture obtained in step 1, continuing to ball mill for 30-90 min, and obtaining a composite material solution after ball milling, and spray drying to obtain a lignin-silicon dioxide composite material, in step 2, the silicon source is a mixture of γ-aminopropyl triethoxysilane and 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane, in step 2, the mass ratio of anhydrous ethanol, γ-aminopropyl triethoxysilane and 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane is 20:2:

1.

2. The method for preparing a lignin-silica composite material according to claim 1, characterized by: in step 1, the mass ratio of lignin, white carbon black and water is 25:25:

50.

3. The method for preparing a lignin-silica composite material according to claim 1, characterized by: in step 1, zirconium oxide is further added during ball milling, and the ball milling time is 1-3 h.

4. The method for preparing a lignin-silica composite material according to claim 1, characterized by: in step 2, the acid added is dilute hydrochloric acid, and the pH value of hydrolysis is 3-5.

5. The method for preparing the lignin-silica composite material as described in claim 1, characterized in that: in step 3, the mass ratio of the preliminary mixture and the reaction solution is 100:

23.

6. The application of the lignin-silicon dioxide composite material prepared by the preparation method of any one of claims 1-5 in the preparation of a rubber finished product.

7. Use according to claim 6, wherein: The preparation steps of the rubber finished product are as follows: adding the lignin-silicon dioxide composite material, natural rubber, carbon black, indirect zinc oxide and stearic acid into a torque rheometer in sequence, and performing dense mixing at a rotation speed of 48 r / min and a temperature of 100 DEG C for 20 min to obtain a mixed rubber; adding the mixed rubber into an open mill to wrap the roller, and adding sulfur and 2, 2'-dithiodibenzothiazole in sequence, and mixing at a temperature of 60 DEG C for 10 min, the interval between the extrusion rollers of the open mill is the minimum thin pass, and the triangular package is punched for 5 times, the interval is adjusted to 2 mm to remove bubbles, and then the sheet is taken out, and a flat vulcanizing machine is used to heat press at a temperature of 150 DEG C for 20 min to solidify and form, and a rubber finished product is obtained.

8. Use according to claim 7, wherein: The mass ratio of the lignin-silicon dioxide composite material, natural rubber, carbon black, indirect zinc oxide and stearic acid is 15:100:35:5:2.5.

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