Rubber vulcanization accelerator as well as preparation method and application thereof

Abstract

The invention relates to the technical field of rubber vulcanization, and provides a rubber vulcanization accelerator as well as a preparation method and application thereof. The invention provides application of a rubber vulcanization accelerator to improvement of tensile strength and tear strength of rubber, and a preparation method of the rubber vulcanization accelerator comprises the following steps: acidizing lignin, and then mixing and reacting the acidized lignin with carbon disulfide under an alkaline condition; and carrying out heat treatment on a product obtained by the reaction to obtain the rubber vulcanization accelerator. Compared with the prior art, the rubber vulcanization accelerator disclosed by the invention has a relatively good vulcanization acceleration effect on rubber, also has a reinforcing effect, is an environment-friendly novel multifunctional rubber additive, and can be applied to production of rubber products.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber vulcanization, and more specifically to a rubber vulcanization accelerator and a preparation method and application thereof. Background Art

[0002] The wastewater produced by alkaline cooking in the pulp and paper industry is dark brown, so it is called black liquor. It is the main source of pollution in the paper industry, accounting for 90% of the pollution in the paper industry. In addition to inorganic substances such as sodium hydroxide and silicon dioxide, black liquor also contains a large amount of lignin. The traditional treatment method of black liquor is mainly to burn it as fuel after evaporation and concentration, but it has low thermal utilization efficiency, produces a large amount of greenhouse gases, and will lead to the loss of potential value-added substances such as lignin contained in the black liquor. The annual output of lignin, a by-product in black liquor, is about 50 million tons, but only 2% is used, and the rest is used as low-value fuel. Lignin is an aromatic natural polymer substance connected by phenyl-propane monomers through chemical bonds such as alkyl-alkyl, alkyl-aryl, and aryl-alkyl. The molecular structure of lignin contains a large number of active groups such as aromatic groups, methoxy groups, alcoholic hydroxyl groups, and phenolic hydroxyl groups, so it can undergo chemical reactions such as hydrolysis, alcoholysis, acidolysis of methoxy groups, alkylation, and hydroxymethylation. Efficient utilization of lignin in papermaking black liquor can not only solve the environmental pollution caused by black liquor, but also produce good economic benefits, which has dual significance for resources and the environment. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a rubber vulcanization accelerator and its preparation method and application. The rubber vulcanization accelerator of the present invention has good vulcanization promoting and reinforcing effects on rubber, is an environmentally friendly new multifunctional rubber additive, and can be used in the production of rubber products.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A rubber vulcanization accelerator is used for improving the tensile strength and tear strength of rubber. The preparation method of the rubber vulcanization accelerator comprises:

[0006] The lignin is subjected to an acid treatment, and then, under alkaline conditions, the acid treated lignin is mixed with carbon disulfide and reacted; the product obtained by the reaction is subjected to a heat treatment to obtain a rubber vulcanization accelerator.

[0007] The preparation reaction process of the rubber vulcanization accelerator of the present invention is as follows Figure 1 shown.

[0008] Xanthate is a type of non-toxic, pollution-free, environmentally friendly rapid vulcanization accelerator that does not contain nitrogen atoms in its molecular structure and therefore does not produce nitrosamines during the vulcanization process.

[0009] Lignin is a complex organic substance that can form chemical chains or hydrogen bonds with the active groups or double bonds of rubber molecules, which has a certain reinforcing effect on rubber. The phenolic hydroxyl groups contained in the lignin structure not only have anti-aging properties, but can also be functionally modified.

[0010] Preferably, the rubber vulcanization accelerator is added in an amount of 1 to 2 wt % in the rubber.

[0011] Preferably, the mass ratio of lignin to carbon disulfide is 1:(0.5-2.0), preferably 1:1.

[0012] Preferably, the acidification treatment comprises: mixing lignin with water, adjusting the pH to 1-6 with acid, and then reacting at 60-100° C. for 2-50 hours; preferably, adjusting the pH to 1-2 with acid.

[0013] Preferably, in the acidification treatment, lignin is mixed with water until the concentration of lignin is 2 to 5 wt %.

[0014] Preferably, the acid includes any one of hydrochloric acid, sulfuric acid and phosphoric acid.

[0015] Preferably, the alkaline condition is provided by sodium hydroxide and / or potassium hydroxide; the pH of the alkaline condition is 10-12.

[0016] Preferably, the acidified lignin is mixed with carbon disulfide at a reaction temperature of 20 to 30° C. and the reaction time is 1 to 5 hours.

[0017] Preferably, the heat treatment is carried out at 60-80° C. for 8-10 hours; and the heat treatment is preferably carried out under vacuum conditions.

[0018] Preferably, the lignin is provided by papermaking black liquor; the papermaking black liquor is dark brown wastewater produced by the alkaline pulping process in the papermaking industry and contains a large amount of lignin; the concentration of lignin in the papermaking black liquor is 25-35wt%.

[0019] The present invention also provides a method for preparing vulcanized rubber, comprising: mixing latex, alkali, rubber vulcanization accelerator, sulfur and zinc oxide, and drying at 60-150° C. to obtain vulcanized rubber;

[0020] The preparation method of the rubber vulcanization accelerator comprises:

[0021] The lignin is subjected to an acid treatment, and then, under alkaline conditions, the acid treated lignin is mixed with carbon disulfide and reacted; the product obtained by the reaction is subjected to a heat treatment to obtain a rubber vulcanization accelerator.

[0022] Preferably, in parts by mass, the mass ratio of the latex dry rubber, alkali, rubber vulcanization accelerator, sulfur and zinc oxide is 100:(0.1-2):(1-5):(1-2):(0.4-0.6), preferably 100:0.2:(1-2):2:0.4.

[0023] Preferably, the alkali comprises sodium hydroxide or potassium hydroxide; the alkali is mixed with other raw materials in the form of a solution.

[0024] The present invention converts the methoxy structure in lignin into a phenolic hydroxyl structure through acidification treatment, thereby achieving a significant increase in the content of the phenolic hydroxyl structure. The phenolic hydroxyl group is reacted with carbon disulfide to load xanthogenic acid on lignin to obtain lignin xanthogenic ester, which has a good vulcanization promoting and reinforcing effect on rubber. The present invention is a new type of environmentally friendly multifunctional rubber additive and can be used in the production of rubber products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the reaction process of the lignin xanthate of the present invention;

[0026] Figure 2 This is the infrared spectrum of the lignin xanthate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0028] In order to further illustrate the present invention, the following examples are used to explain it in detail. The raw materials used in the following examples and comparative examples of the present invention are all commercially available products.

[0029] The papermaking black liquor used in the embodiments of the present invention and the comparative examples was provided by Hainan Jinhai Pulp & Paper Co., Ltd.; carbon disulfide was purchased from Shanghai Aladdin Biochemical Co., Ltd.; sodium hydroxide, potassium hydroxide, hydrochloric acid and sulfuric acid were purchased from Xilong Science Co., Ltd.; sulfur dispersion, zinc oxide dispersion and zinc diethyldithiocarbamate (ZDC) dispersion were provided by Zhejiang Tianhe Resin Co., Ltd.; concentrated natural latex was provided by Hainan Rubber Group Corporation.

[0030] Example 1

[0031] The preparation method of the rubber vulcanization accelerator of this embodiment, the reaction process is as follows Figure 1 As shown, the specific steps include:

[0032] (1) Add 10 g of papermaking black liquor and 100 mL of pure water to a 500 mL three-necked flask equipped with an electric stirrer and a reflux condenser, and stir to fully dissolve the papermaking black liquor;

[0033] (2) Add 5 mL of hydrochloric acid to the system obtained in step (2) to adjust the pH of the system to 2, acidify the papermaking black liquor, control the reaction temperature to 100° C., continue stirring, react at a constant temperature for 10 hours, cool to room temperature, add 5 g of sodium hydroxide, adjust the pH of the system to 12, and then slowly drop 5 mL of carbon disulfide (control the mass ratio of lignin to carbon disulfide to be 1:1), react for 2 hours, stand to allow the product to fully precipitate, filter, wash with pure water to neutrality, and dry in a vacuum drying oven at 60° C. for 8 hours to obtain lignin xanthate; perform infrared analysis on the lignin xanthate to obtain the following: Figure 2 The spectrum shown is from Figure 2 It can be seen that the infrared spectrum of lignin-loaded xanthate is at 1365 cm -1 and 867cm -1 C=S and CS bonds appeared at the positions respectively, indicating that the lignin in the black liquor was successfully loaded with the promoter xanthate after the reaction.

[0034] The prepared lignin xanthate is used as a rubber vulcanization accelerator to prepare a vulcanized rubber film, which specifically includes the following steps:

[0035] (1) Preparation of compound latex film: Take 100 parts by mass of concentrated natural latex (calculated by the mass of dry rubber, i.e., 100 parts of concentrated natural latex dry rubber), add 0.2 parts of potassium hydroxide, 2.0 parts of lignin xanthate, 1.0 parts of sulfur and 0.4 parts of zinc oxide, stir, and mix well to obtain compound latex, which is then poured onto a glass plate and naturally dried to form a compound latex film; potassium hydroxide is mixed with other raw materials in the form of a solution, and the content of potassium hydroxide in the potassium hydroxide solution is 0.5 mol / L; sulfur and zinc oxide are mixed with other raw materials in the form of aqueous dispersions respectively; in the sulfur dispersion, the mass concentration of sulfur is 60 wt%; in the zinc oxide dispersion, the mass concentration of zinc oxide is 60 wt%; (2) Preparation of vulcanized latex film: The compound latex film is washed in a 60°C water bath, and then vulcanized in a 100°C drying oven for 2 hours to obtain a vulcanized film.

[0036] Example 2

[0037] The preparation method of the rubber vulcanization accelerator of this embodiment comprises the following steps:

[0038] (1) Add 20 g of papermaking black liquor and 120 mL of pure water to a 500 mL three-necked flask equipped with an electric stirrer and a reflux condenser, and stir to fully dissolve the papermaking black liquor;

[0039] (2) Add 8 mL of hydrochloric acid to the system obtained in step (2), adjust the pH of the system to about 2, acidify the papermaking black liquor, control the reaction temperature to 100° C., continue stirring, react at a constant temperature for 12 hours, cool to room temperature, add 6 g of sodium hydroxide, adjust the pH of the system to 12, and then slowly drop 8 mL of carbon disulfide (control the mass ratio of lignin to carbon disulfide to be 1:1), react for 3 hours, let stand to allow the product to fully precipitate, filter, wash with pure water to neutrality, and dry in a vacuum drying oven at 60° C. for 8 hours to obtain lignin xanthate.

[0040] The prepared lignin xanthate is used as a rubber vulcanization accelerator to prepare a vulcanized rubber film, which specifically includes the following steps:

[0041] (1) Preparation of a latex film: 100 parts by mass of concentrated natural latex (based on the mass of dry rubber) are added with 0.2 parts of potassium hydroxide, 1.8 parts of lignin xanthate, 1.0 parts of sulfur and 0.4 parts of zinc oxide, and stirred to obtain a latex after uniform mixing. The latex is poured onto a glass plate and naturally dried to form a latex film; potassium hydroxide is mixed with other raw materials in the form of a solution, and the content of potassium hydroxide in the potassium hydroxide solution is 0.5 mol / L; sulfur and zinc oxide are mixed with other raw materials in the form of aqueous dispersions; the mass concentration of sulfur in the sulfur dispersion is 60 wt%; the mass concentration of zinc oxide in the zinc oxide dispersion is 60 wt%;

[0042] (2) Preparation of vulcanized latex film: The formulated latex film was washed in a 60°C water bath and vulcanized in a 100°C drying oven for 2 h to obtain a vulcanized film.

[0043] Example 3

[0044] The preparation method of the rubber vulcanization accelerator of this embodiment comprises the following steps:

[0045] (1) Add 30 g of papermaking black liquor and 150 mL of pure water to a 500 mL three-necked flask equipped with an electric stirrer and a reflux condenser, and stir to fully dissolve the papermaking black liquor;

[0046] (2) Add 10 mL of hydrochloric acid to the system obtained in step (2), adjust the pH of the system to 2, acidify the papermaking black liquor, control the reaction temperature to 85°C, continue stirring, react at a constant temperature for 18 hours, cool to room temperature, add 8 g of sodium hydroxide, adjust the pH of the system to 12, and then slowly drop 8 mL of carbon disulfide (control the mass ratio of lignin to carbon disulfide to be 1:1), react for 4 hours, let stand to allow the product to fully precipitate, filter, wash with pure water to neutrality, and dry in a vacuum drying oven at 60°C for 8 hours to obtain lignin xanthate.

[0047] The prepared lignin xanthate is used as a rubber vulcanization accelerator to prepare a vulcanized rubber film, which specifically includes the following steps:

[0048] (1) Preparation of a latex film: 100 parts of concentrated natural rubber latex are added, based on the mass of dry rubber, with 0.2 parts of potassium hydroxide, 1.6 parts of lignin xanthate, 1.0 parts of sulfur and 0.4 parts of zinc oxide, stirred, and mixed evenly to obtain a latex, which is then poured onto a glass plate and naturally dried to form a latex film; potassium hydroxide is mixed with other raw materials in the form of a solution, and the content of potassium hydroxide in the potassium hydroxide solution is 0.5 mol / L; sulfur and zinc oxide are mixed with other raw materials in the form of aqueous dispersions; the mass concentration of sulfur in the sulfur dispersion is 60 wt%; the mass concentration of zinc oxide in the zinc oxide dispersion is 60 wt%;

[0049] (2) Preparation of vulcanized latex film: The formulated latex film was washed in a 60°C water bath and vulcanized in a 100°C drying oven for 2 h to obtain a vulcanized film.

[0050] Example 4

[0051] The preparation method of the rubber vulcanization accelerator of this embodiment comprises the following steps:

[0052] (1) Add 40 g of papermaking black liquor and 150 mL of pure water to a 500 mL three-necked flask equipped with an electric stirrer and a reflux condenser, and stir to fully dissolve the papermaking black liquor;

[0053] (2) Add 12 mL of hydrochloric acid to the system obtained in step (2), adjust the pH of the system to 2, acidify the papermaking black liquor, control the reaction temperature to 80°C, continue stirring, react at a constant temperature for 24 hours, cool to room temperature, add 10 g of sodium hydroxide, adjust the pH of the system to 12, and then slowly drop 10 mL of carbon disulfide (control the mass ratio of lignin to carbon disulfide to be 1:1), react for 4 hours, let stand to allow the product to fully precipitate, filter, wash with pure water to neutrality, and dry in a vacuum drying oven at 60°C for 8 hours to obtain lignin xanthate.

[0054] The prepared lignin xanthate is used as a rubber vulcanization accelerator to prepare a vulcanized rubber film, which specifically includes the following steps:

[0055] (1) Preparation of a latex film: 100 parts of concentrated natural rubber latex are added, based on the mass of dry rubber, with 0.2 parts of potassium hydroxide, 1.5 parts of lignin xanthate, 1.0 parts of sulfur and 0.4 parts of zinc oxide, stirred, and mixed evenly to obtain a latex, which is then poured onto a glass plate and naturally dried to form a latex film; potassium hydroxide is mixed with other raw materials in the form of a solution, and the content of potassium hydroxide in the potassium hydroxide solution is 0.5 mol / L; sulfur and zinc oxide are mixed with other raw materials in the form of aqueous dispersions; the mass concentration of sulfur in the sulfur dispersion is 60 wt%; the mass concentration of zinc oxide in the zinc oxide dispersion is 60 wt%;

[0056] (2) Preparation of vulcanized latex film: The formulated latex film was washed in a 60°C water bath and vulcanized in a 100°C drying oven for 2 h to obtain a vulcanized film.

[0057] Example 5

[0058] The preparation method of the rubber vulcanization accelerator of this embodiment comprises the following steps:

[0059] (1) Add 40 g of papermaking black liquor and 200 mL of pure water to a 500 mL three-necked flask equipped with an electric stirrer and a reflux condenser, and stir to fully dissolve the papermaking black liquor;

[0060] (2) Add 15 mL of hydrochloric acid to the system obtained in step (2), adjust the pH of the system to 2, acidify the papermaking black liquor, control the reaction temperature to 75°C, continue stirring, react at a constant temperature for 48 hours, cool to room temperature, add 15 g of sodium hydroxide, adjust the pH of the system to 12, and then slowly drop 15 mL of carbon disulfide (control the mass ratio of lignin to carbon disulfide to be 1:1), react for 5 hours, let stand to allow the product to fully precipitate, filter, wash with pure water to neutrality, and dry in a vacuum drying oven at 60°C for 8 hours to obtain lignin xanthate.

[0061] The prepared lignin xanthate is used as a rubber vulcanization accelerator to prepare a vulcanized rubber film, which specifically includes the following steps:

[0062] (1) Preparation of a latex film: 100 parts of concentrated natural rubber latex are added, based on the mass of dry rubber, with 0.2 parts of potassium hydroxide, 1.2 parts of lignin xanthate, 1.0 parts of sulfur and 0.4 parts of zinc oxide, stirred, and mixed evenly to obtain a latex, which is then poured onto a glass plate and naturally dried to form a latex film; potassium hydroxide is mixed with other raw materials in the form of a solution, and the content of potassium hydroxide in the potassium hydroxide solution is 0.5 mol / L; sulfur and zinc oxide are mixed with other raw materials in the form of aqueous dispersions; the mass concentration of sulfur in the sulfur dispersion is 60 wt%; the mass concentration of zinc oxide in the zinc oxide dispersion is 60 wt%;

[0063] (2) Preparation of vulcanized latex film: The formulated latex film was washed in a 60°C water bath and vulcanized in a 100°C drying oven for 2 h to obtain a vulcanized film.

[0064] Example 6

[0065] The only difference between this embodiment and embodiment 1 is that in this embodiment, concentrated natural latex is replaced by styrene-butadiene latex with a solid content of 60%, and the dry rubber mass of styrene-butadiene latex is the same as the dry rubber mass of concentrated natural latex; the usage amounts of other raw materials are adjusted accordingly according to the dry rubber mass of styrene-butadiene latex; and the steps of preparing the vulcanized rubber film are carried out with reference to that in embodiment 1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the commercially available rubber vulcanization accelerator ZDC is used to replace lignin xanthate in this comparative example, and the steps of preparing the vulcanized rubber film are carried out with reference to those in Example 1.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that in this comparative example, 2.0 parts of lignin xanthate are replaced by 2.0 parts of lignin, and the steps of preparing the vulcanized rubber film are carried out with reference to that in Example 1.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that in this comparative example, 2.0 parts of lignin xanthate are replaced by 5.0 parts of lignin xanthate, and the steps of preparing the vulcanized rubber film are carried out with reference to that in Example 1.

[0072] Test example

[0073] The performance test and analysis of the samples obtained in the embodiments and comparative examples of the present invention are performed, and the detection indicators and methods are as follows:

[0074] Vulcanization characteristics of compound latex film: The determination of vulcanization characteristics of compound latex film is carried out in accordance with GB / T 9869-2014 Determination of vulcanization characteristics of rubber compounds using the disc oscillation vulcanizer method.

[0075] Tensile strength of vulcanized rubber film: The tensile strength of vulcanized rubber film is tested in accordance with GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0076] Vulcanized rubber film tear strength: The tear strength of the vulcanized rubber film is tested in accordance with the test standard GB / T 529-2008 Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped specimen).

[0077] The test results are shown in Table 1.

[0078] Table 1

[0079]

[0080] It can be seen from Table 1 that, compared with the comparative example, the vulcanized rubber film prepared by using the lignin xanthate prepared in the embodiment of the present invention as a rubber vulcanization accelerator has higher tensile strength and tear strength.

[0081] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Use of a rubber vulcanization accelerator in improving the tensile strength and tear strength of rubber, characterized in that: The preparation method of the rubber vulcanization accelerator comprises: The lignin is subjected to an acid treatment, and then, under alkaline conditions, the acid treated lignin is mixed with carbon disulfide and reacted; the product obtained by the reaction is subjected to a heat treatment to obtain a rubber vulcanization accelerator.

2. The use according to claim 1, characterized in that: The rubber vulcanization accelerator is added in an amount of 1 to 2 wt % in the rubber.

3. The use according to claim 1, characterized in that: The mass ratio of the lignin to carbon disulfide is 1:(0.5-2.0).

4. The use according to claim 1, characterized in that: The acidification treatment comprises: mixing lignin with water, adjusting the pH to 1-6 with acid, and then reacting at 60-100° C. for 2-50 hours.

5. The use according to claim 1, characterized in that: The pH of the alkaline condition is 10-12.

6. The use according to claim 1, characterized in that: The reaction temperature is 20-30°C.

7. The use according to claim 1, characterized in that: The reaction time is 1 to 5 hours.

8. The use according to claim 1, characterized in that: The heat treatment is carried out at 60-80° C. for 8-10 hours.

9. A method for preparing vulcanized rubber, characterized in that: include: Mixing latex, alkali, rubber vulcanization accelerator, sulfur and zinc oxide, and drying at 60-150° C. to obtain vulcanized rubber; The preparation method of the rubber vulcanization accelerator comprises: Acidifying the lignin, and then mixing and reacting the acidified lignin with carbon disulfide under alkaline conditions; The product obtained by the reaction is subjected to heat treatment to obtain a rubber vulcanization accelerator.

10. The method for preparing vulcanized rubber according to claim 9, characterized in that: In parts by mass, the mass ratio of the latex dry rubber, alkali, rubber vulcanization accelerator, sulfur and zinc oxide is 100:(0.1-2):(1-5):(1-2):(0.4-0.6).

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