Lignin cobalt salt and preparation method thereof
The lignin cobalt salt addresses the issues of migration and diffusion in existing cobalt salts by forming a stable compound with improved anti-aging and mechanical properties through a series of chemical treatments, enhancing bonding and mechanical strength.
Patent Information
- Application Number
- CN202411414820.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2024-12-10
AI Technical Summary
Existing cobalt salts used for bonding rubber and metal have issues with migration and diffusion, affecting mechanical properties and anti-aging performance, and their synthesis often uses environmentally harmful solvents.
A lignin cobalt salt is prepared by treating lignin with hydrochloric acid, followed by reactions with methanol, serinol, maleic anhydride, and cobalt chloride to form a lignin cobalt salt with improved anti-aging and mechanical properties.
The lignin cobalt salt enhances bonding and mechanical properties while reducing the negative effects of free acid migration, and improves anti-aging performance by capturing free radicals and participating in vulcanization.
Smart Images
Figure QLYQS_1 
Figure QLYQS_2 
Figure QLYQS_3
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of adhesives, in particular to a lignin cobalt salt and a preparation method thereof. Background Art
[0002] Cobalt salts are mainly used to enhance the bonding between rubber and metal. They have a very obvious effect on the bonding between rubber and copper-plated metal. They are widely used in products such as radial tires and steel hoses. There are many types of cobalt salts, most of which are purple-red flake solids. At present, most steel cords are brass-plated or galvanized. When bonding with rubber, the exclusive adhesive is organic acid cobalt salt. In addition to being used in the bonding formula of high-performance steel radial tires, it can also be used alone in the manufacture of high-bearing steel hoses and other fields.
[0003] However, the cobalt borate and cobalt neodecanoate in the prior art are mostly mixed carboxylic acids mainly composed of medium- and short-chain acids, which have strong acidity, small molecular weight and are easy to migrate and diffuse, and have a great influence on mechanical properties and anti-aging properties. In addition, the reaction raw materials and synthesis technologies mostly use benzene solvents, which are not in line with the development concept of green environmental protection. Therefore, the present invention uses lignin as a raw material to generate a lignin cobalt salt with good anti-aging properties. Summary of the invention
[0004] The object of the present invention is to provide a lignin cobalt salt and a preparation method thereof, so as to solve the problems existing in the prior art.
[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0006] A lignin cobalt salt is prepared by treating lignin with hydrochloric acid, and then reacting with methanol aqueous solution and serinol to obtain modified lignin; and reacting the modified lignin with maleic anhydride, and then treating with a cobalt chloride aqueous solution to obtain the lignin.
[0007] A method for preparing a lignin cobalt salt comprises the following preparation steps:
[0008] (1) Mix lignin and hydrochloric acid in a mass ratio of 1:8-10, stir and reflux at a speed of 200-300 r / min at a water bath temperature of 60-70°C for 20-30 min, filter and wash with pure water until neutral, and dry at 70-80°C for 6-8 h to obtain pretreated lignin;
[0009] (2) The pretreated lignin and sodium hydroxide solution were mixed uniformly at a mass ratio of 1:20-25, and then 0.8-1.2 times the mass of the pretreated lignin was added with a 55% formaldehyde aqueous solution and 0.2-0.3 times the mass of the pretreated lignin was added, and the mixture was stirred and refluxed at 70-80°C and 200-300 r / min for 2-3 hours, centrifuged and washed with pure water until neutral, and dried at 70-80°C for 6-8 hours to obtain modified lignin;
[0010] (3) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:8-10, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.08-0.12 times the mass of the modified lignin. The mixture was stirred and refluxed at 70-80°C and 300-500 r / min for 3-4 hours. The mixture was poured into pure water (mass fraction) 30-40 times the mass of the modified lignin and continued to be stirred for 3-5 minutes. The mixture was centrifuged and washed with pure water for 3-5 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 20-30 minutes. The mixture was centrifuged and washed with pure water for 3-5 times. The mixture was dried at 70-80°C for 6-8 hours to obtain lignin cobalt salt.
[0011] As an optimization, the lignin in step (1) has a purity greater than 99% and is purchased from Nantong Runfeng Petrochemical Co., Ltd.
[0012] As an optimization, the hydrochloric acid in step (1) has a mass fraction of 36% to 38%.
[0013] As an optimization, the concentration of the sodium hydroxide solution in step (2) is 0.1 mol / L.
[0014] As an optimization, the reaction process of the modified lignin in step (2) is as follows:
[0015] .
[0016] As an optimization, the reaction process of the modified lignin and maleic anhydride in step (3) is as follows:
[0017] .
[0018] As an optimization, the reaction process of immersing in a 10% by mass aqueous solution of cobalt chloride in step (3) is as follows:
[0019] .
[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:
[0021] In the preparation of lignin cobalt salt, the lignin is treated with hydrochloric acid, and then reacted with methanol aqueous solution and serinol to obtain modified lignin; the modified lignin is reacted with maleic anhydride, and then treated with cobalt chloride aqueous solution to obtain lignin cobalt salt.
[0022] Firstly, the present invention uses lignin as raw material, which is a green, environmentally friendly and renewable resource; hydrochloric acid is used to pretreat the lignin, so that a large number of anisole structures on the lignin are demethylated to form more benzene polyphenol structures, which can capture free radicals and have good anti-aging performance.
[0023] Secondly, through the phenolic reaction, the phenolic hydroxyl group of lignin is grafted at the ortho position to form a hindered phenol structure, which further improves the antioxidant effect. Finally, maleic anhydride and alcohol hydroxyl group react to form a carboxyl group, and a double bond is introduced. The carboxyl group combines with the cobalt salt, and the double bond participates in the vulcanization of the rubber to achieve a binding effect, avoiding the negative impact of free carboxylic acid, and at the same time participates in vulcanization cross-linking to achieve good mechanical properties. DETAILED DESCRIPTION
[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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 making creative work are within the scope of protection of the present invention.
[0025] In order to more clearly illustrate the method provided by the present invention, the following examples are described in detail.
[0026] Example 1
[0027] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0028] (1) Mix lignin and 36% hydrochloric acid solution in a mass ratio of 1:8, stir and reflux at a speed of 200 r / min at a water bath temperature of 60°C for 30 min, filter and wash with pure water until neutral, and dry at 70°C for 8 h to obtain pretreated lignin;
[0029] (2) The pretreated lignin and 0.1 mol / L sodium hydroxide solution were mixed uniformly at a mass ratio of 1:20, and then 0.8 times the mass of the pretreated lignin was added with a 55% formaldehyde aqueous solution and 0.2 times the mass of the pretreated lignin was added. The mixture was stirred and refluxed at 70°C and 200 r / min for 3 h, centrifuged and washed with pure water until neutral, and dried at 70°C for 8 h to obtain modified lignin.
[0030] (3) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:8, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.08 times the mass of the modified lignin. The mixture was stirred and refluxed at 70°C and 300 r / min for 4 h. The mixture was poured into pure water (mass fraction) 30 times the mass of the modified lignin and stirred for 5 min. The mixture was centrifuged and washed with pure water for 3 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 20 min. The mixture was centrifuged and washed with pure water for 3 times. The mixture was dried at 70°C for 8 h to obtain lignin cobalt salt.
[0031] Example 2
[0032] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0033] (1) Mix lignin and 37% hydrochloric acid solution in a mass ratio of 1:9, stir and reflux at 250 r / min for 25 min in a water bath at 65 °C, filter and wash with pure water until neutral, and dry at 75 °C for 7 h to obtain pretreated lignin;
[0034] (2) The pretreated lignin and 0.1 mol / L sodium hydroxide solution were mixed uniformly at a mass ratio of 1:22, and then a 55% formaldehyde aqueous solution with a mass fraction of 1 times the mass of the pretreated lignin and a serine with a mass fraction of 0.25 times the mass of the pretreated lignin were added, and the mixture was stirred and refluxed at 75°C and 250 r / min for 2.5 h, centrifuged and washed with pure water until neutral, and dried at 75°C for 7 h to obtain modified lignin;
[0035] (3) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:9, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.1 times the mass of the modified lignin. The mixture was stirred and refluxed at 75°C and 400 r / min for 3.5 h. The mixture was poured into pure water (mass fraction) 35 times the mass of the modified lignin and stirred for 4 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 25 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was dried at 75°C for 7 h to obtain lignin cobalt salt.
[0036] Example 3
[0037] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0038] (1) Mix lignin and 36% to 38% hydrochloric acid solution in a mass ratio of 1:10, stir and reflux at 300 r / min for 20 min in a water bath at 70°C, filter and wash with pure water until neutral, and dry at 80°C for 6 h to obtain pretreated lignin;
[0039] (2) Pretreated lignin and 0.1 mol / L sodium hydroxide solution were mixed uniformly at a mass ratio of 1:25, and then 1.2 times the mass of the pretreated lignin and 55% formaldehyde aqueous solution and 0.3 times the mass of the pretreated lignin were added, and the mixture was stirred and refluxed at 80°C and 200 r / min for 2 h, centrifuged and washed with pure water until neutral, and dried at 80°C for 6 h to obtain modified lignin;
[0040] (3) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:10, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.12 times the mass of the modified lignin. The mixture was stirred and refluxed at 80°C and 500 r / min for 3 h. The mixture was poured into pure water (40 times the mass of the modified lignin) and stirred for 3 min. The mixture was centrifuged and washed with pure water for 5 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 30 min. The mixture was centrifuged and washed with pure water for 5 times. The mixture was dried at 80°C for 6 h to obtain lignin cobalt salt.
[0041] Comparative Example 1
[0042] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0043] (1) Mix lignin and 0.1 mol / L sodium hydroxide solution in a mass ratio of 1:22, then add 55% formaldehyde aqueous solution with a mass fraction of 1 times the mass of lignin and 0.25 times the mass of serinol, stir and reflux at 75°C and 250 r / min for 2.5 h, centrifuge and wash with pure water until neutral, and dry at 75°C for 7 h to obtain modified lignin;
[0044] (2) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:9, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.1 times the mass of the modified lignin. The mixture was stirred and refluxed at 75°C and 400 r / min for 3.5 h. The mixture was poured into pure water (mass fraction) 35 times the mass of the modified lignin and stirred for 4 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 25 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was dried at 75°C for 7 h to obtain lignin cobalt salt.
[0045] Comparative Example 2
[0046] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0047] (1) Mix lignin and 37% hydrochloric acid solution in a mass ratio of 1:9, stir and reflux at 250 r / min for 25 min in a water bath at 65 °C, filter and wash with pure water until neutral, and dry at 75 °C for 7 h to obtain pretreated lignin;
[0048] (2) The pretreated lignin and 0.1 mol / L sodium hydroxide solution were mixed uniformly at a mass ratio of 1:22, and then a 55% formaldehyde aqueous solution with a mass fraction of 1 times the mass of the pretreated lignin and a serine with a mass fraction of 0.25 times the mass of the pretreated lignin were added, and the mixture was stirred and refluxed at 75°C and 250 r / min for 2.5 h, centrifuged and washed with pure water until neutral, and dried at 75°C for 7 h to obtain modified lignin;
[0049] (3) The modified lignin, succinic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:9, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.1 times the mass of the modified lignin. The mixture was stirred and refluxed at 75°C and 400 r / min for 3.5 h. The mixture was poured into pure water (mass fraction) 35 times the mass of the modified lignin and stirred for 4 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 25 min. The mixture was centrifuged and washed with pure water for 4 times. The mixture was dried at 75°C for 7 h to obtain lignin cobalt salt.
[0050] Comparative Example 3
[0051] A method for preparing a lignin cobalt salt mainly comprises the following preparation steps:
[0052] Sodium lignin sulfonate HF-1, maleic anhydride and N,N-dimethylacetamide were mixed evenly in a mass ratio of 1:1:9, and concentrated sulfuric acid with a mass fraction of 98% which was 0.1 times the mass of the modified lignin was added, and the mixture was stirred and refluxed at 75°C and 400r / min for 3.5h, poured into pure water with a mass fraction of 35 times the mass of the modified lignin and continued to be stirred for 4min, centrifuged and washed with pure water for 4 times, then immersed in a 10% mass fraction cobalt chloride aqueous solution, ultrasonicated for 25min, centrifuged and washed with pure water for 4 times, and dried at 75°C for 7h to obtain lignin cobalt salt.
[0053] Comparative Example 4
[0054] A traditional rubber cobalt salt adhesive is selected: cobalt neodecanoate.
[0055] Test Example 1
[0056] Effects of using lignin cobalt salt
[0057] Preparation of rubber compound: 100 parts of natural rubber SMR10, 8 parts of zinc oxide, 5 parts of sulfur HD-OT20, 2 parts of antioxidant 4020, 1 part of accelerator DZ, 0.3 parts of anti-scorch agent CTP, and 2 parts of the products obtained in each embodiment and comparative example were weighed by mass, the XSM-500 type internal mixer was heated to 90°C, the speed was set to 80r / min, the natural rubber SMR10 was added and plasticized for 50s, and then zinc oxide and antioxidant 4020 were added and plasticized for 200s, and then the rubber was discharged, and the mixture was placed on an open mixer at 55°C, with a roller distance of 1.4mm and rolled for 1min, and then sulfur HD-OT20, the products obtained in each embodiment and comparative example, accelerator DZ, and anti-scorch agent CTP were added and mixed for 4min, and the roller distance was adjusted to 0.5mm and passed 6 times to obtain a rubber compound.
[0058] 1. Test of the bonding performance between rubber and steel cord
[0059] 0.25+6+12*0.225HT copper-plated steel cord and rubber were vulcanized at a temperature of 151°C and a pressure of 10 MPa for 8 minutes. The samples were naturally cooled to room temperature and then taken out to obtain steel cord / rubber vulcanization specimens. The steel wire T extraction force was tested by a GT-AI-7000M tensile testing machine in accordance with the national standard GB / T 16586-2014, and the extraction speed was 200 mm / min.
[0060] 2. Test of tensile strength of rubber after vulcanization
[0061] The rubber compound was vulcanized at a temperature of 151°C and a pressure of 10 MPa for 8 minutes, and then naturally cooled to room temperature and taken out to obtain a rubber vulcanization specimen. The tensile strength of the specimen was tested using a GT-AI-7000M tensile testing machine according to GB / T528 standard, with a tensile speed of 500 mm / min.
[0062] 3. Anti-aging performance test
[0063] The rubber vulcanized sample was placed in a thermal oxygen aging chamber for aging test, treated at 105°C for 3 days, and the tensile strength after the aging test was tested; the tensile strength retention rate was calculated
[0064] The results are shown in Table 1.
[0065] Table 1
[0066] Extraction force Tensile Strength Tensile strength retention Example 1 741N 25.0MPa 97.2% Example 2 745N 25.2MPa 96.8% Example 3 744N 25.3MPa 97.1% Comparative Example 1 740N 25.2MPa 89.7% Comparative Example 2 706N 21.7MPa 96.5% Comparative Example 3 688N 21.3MPa 85.3% Comparative Example 4 742N 20.5MPa 76.8%
[0067] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the lignin cobalt salt prepared by the present invention has a good use effect.
[0068] It can be seen from Comparative Example 1 that pre-treating lignin with hydrochloric acid demethylates a large number of anisole structures on the lignin to form more benzene polyphenol structures. The benzene polyphenol structures can capture free radicals and have good anti-aging properties.
[0069] Comparative Example 2 shows that, compared with succinic anhydride, the double bonds on maleic anhydride enable the lignin cobalt salt to participate in the vulcanization of the rubber, thereby making the overall bonding tighter and improving the extraction force and tensile strength.
[0070] It can be seen from Comparative Example 3 that compared with the direct reaction of sodium lignin sulfonate and cobalt chloride, the lignin cobalt salt prepared by the present invention has more polyphenol structures formed by pretreatment demethylation and other groups grafted at the ortho position of the phenolic hydroxyl group to form hindered phenol, both of which further improve the antioxidant performance.
[0071] It can be seen from Comparative Example 4 that, compared with the use of the traditional rubber cobalt salt adhesive cobalt neodecanoate, the lignin cobalt salt prepared by the present invention can improve the overall tensile strength, while avoiding the free release of small molecule acids to accelerate rubber aging, it also has the effect of capturing free radicals, thereby improving the aging resistance.
[0072] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.
Claims
1. A lignin cobalt salt, characterized in that The lignin cobalt salt is prepared by treating lignin with hydrochloric acid, and then reacting with methanol aqueous solution and serinol to obtain modified lignin; and reacting the modified lignin with maleic anhydride, and then treating it with cobalt chloride aqueous solution to obtain the lignin.
2. A method for preparing the lignin cobalt salt according to claim 1, characterized in that: The method comprises the following preparation steps: (1) Mix lignin and hydrochloric acid in a mass ratio of 1:8-10, stir and reflux at a speed of 200-300 r / min at a water bath temperature of 60-70°C for 20-30 min, filter and wash with pure water until neutral, and dry at 70-80°C for 6-8 h to obtain pretreated lignin; (2) The pretreated lignin and sodium hydroxide solution were mixed uniformly at a mass ratio of 1:20-25, and then 0.8-1.2 times the mass of the pretreated lignin was added with a 55% formaldehyde aqueous solution and 0.2-0.3 times the mass of the pretreated lignin was added, and the mixture was stirred and refluxed at 70-80°C and 200-300 r / min for 2-3 hours, centrifuged and washed with pure water until neutral, and dried at 70-80°C for 6-8 hours to obtain modified lignin; (3) The modified lignin, maleic anhydride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:1:8-10, and 98% concentrated sulfuric acid (mass fraction) was added, which was 0.08-0.12 times the mass of the modified lignin. The mixture was stirred and refluxed at 70-80°C and 300-500 r / min for 3-4 hours. The mixture was poured into pure water (mass fraction) 30-40 times the mass of the modified lignin and continued to be stirred for 3-5 minutes. The mixture was centrifuged and washed with pure water for 3-5 times. The mixture was then immersed in a 10% cobalt chloride aqueous solution and ultrasonicated for 20-30 minutes. The mixture was centrifuged and washed with pure water for 3-5 times. The mixture was dried at 70-80°C for 6-8 hours to obtain lignin cobalt salt.
3. The method for preparing a lignin cobalt salt according to claim 2, characterized in that: The hydrochloric acid in step (1) is hydrochloric acid with a mass fraction of 36% to 38%.
4. The method for preparing a lignin cobalt salt according to claim 2, characterized in that: The concentration of the sodium hydroxide solution in step (2) is 0.1 mol / L.
5. The method for preparing a lignin cobalt salt according to claim 2, characterized in that: The reaction process of the modified lignin in step (2) is as follows: 。 6. The method for preparing a lignin cobalt salt according to claim 2, characterized in that: The reaction process of the modified lignin and maleic anhydride in step (3) is as follows: 。 7. The method for preparing a lignin cobalt salt according to claim 2, characterized in that: The reaction process of immersing in a 10% by mass aqueous solution of cobalt chloride in step (3) is as follows: 。