Lignin-butadiene styrene rubber composite rubber and preparation method and application thereof

Abstract

The invention discloses a lignin-butadiene styrene rubber composite rubber and a preparation method and application thereof, the preparation method comprises the following steps: treating pulping black liquor by using a 5-20 [mu] m prefilter to obtain black liquor lignin; the solid content of the pulping black liquor is 10-20%, the density is 1.03-1.10 g / mL, and the pH value is 11.0-13.5; carrying out concentration treatment on the black liquor lignin by adopting a nanofiltration membrane to obtain lignin liquid; the molecular weight of the nanofiltration membrane is 1000-8000, the treatment condition is 40-70 DEG C, and the membrane inlet pressure is 10-40 bar; adding styrene-butadiene latex into the lignin liquid, and stirring at 50-500r / min for 5-20 minutes to obtain a composite emulsion; inorganic acid is added into the composite emulsion for acidification treatment, the pH value is adjusted to be 2.0-5.0, after composite rubber is separated out, a plate-and-frame filter press is adopted for conducting solid-liquid separation on the composite rubber, the pressing pressure of the plate-and-frame filter press is 10-20 kg, then water is used for washing, the washing temperature is 40-60 DEG C, and hot air drying is conducted. The composite rubber disclosed by the invention has good mechanical properties and ageing resistance when being applied to rubber products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite materials, and particularly relates to a lignin-styrene-butadiene rubber composite glue as well as a preparation method and application thereof. BACKGROUND

[0002] The pulp and paper industry is one of the most serious pollution industries in China, and the black liquor pollution problem is particularly prominent. As the main component of black liquor, lignin still faces great challenges in its treatment and resource utilization. In the pulping process, lignin is severely damaged by cooking chemicals, and the raw material sources are diverse and complex in structure, making it difficult to separate and efficiently utilize. At present, most of the black liquor from pulping is only used as fuel to recover energy and alkali, and the actual utilization rate of lignin is low, which cannot realize high-value utilization, resulting in resource waste and environmental pressure.

[0003] Lignin is a natural polymer composed of aromatic alcohol polymers, widely exists in plant cell walls, accounting for about 20-25% of the dry weight of plant cells, and is the second largest renewable organic resource in nature. Lignin has a variety of active functional groups in its molecular structure, good reaction activity and modification potential, and can be used to produce dispersants, cement water reducing agents and other chemical products, and has broad prospects in replacing petroleum-based carbon materials. The development of lignin-based materials is increasingly valued. On the other hand, the rubber industry, as a traditional manufacturing industry, is increasingly in urgent need of green additives such as rice husk ash silica and bio-based carbon materials and their application processes under the pressure of policies such as carbon tax. Although lignin has high carbon content and is renewable, its application in rubber (such as styrene-butadiene rubber) still has problems such as poor dispersity, easy agglomeration, complex process and large pollution in the extraction process. Existing extraction methods mostly rely on alkali or solvent dissolution, not only producing secondary pollution, but also increasing the application cost, which limits its promotion in the rubber industry. Therefore, developing environmentally friendly and efficient lignin extraction technology and promoting its high-value application in rubber has important significance for realizing the resource utilization of black liquor and helping the green transformation of the rubber industry. SUMMARY

[0004] In order to improve the utilization rate of pulping black liquor, solve the problems of heavy pollution, high energy consumption, insufficient resource recovery and other problems existing in the existing pulping black liquor treatment process, and overcome the technical bottleneck that lignin is difficult to disperse in styrene-butadiene rubber and easy to agglomerate, the present application provides a lignin-styrene-butadiene rubber composite glue and its preparation method and application. The method extracts lignin from black liquor by using an environmentally friendly and efficient nanofiltration membrane technology, and co-precipitates the lignin with a styrene-butadiene latex to prepare a lignin-styrene-butadiene rubber composite glue. The process not only significantly improves the dispersibility of lignin in the rubber matrix and avoids the agglomeration phenomenon in the traditional dry mixing process, but also realizes the high-value utilization of pulping black liquor, and the obtained composite glue material has good mechanical properties and aging resistance.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] In one aspect of the present application, a preparation method of a lignin-styrene-butadiene rubber composite glue is provided, which specifically comprises the following steps:

[0007] (1) treating the pulping black liquor with a pre-filter of 5-20 μm to obtain black liquor lignin; the solid content of the pulping black liquor is 10-20%, the density is 1.03-1.10 g / mL, and the pH value is 11.0-13.5;

[0008] (2) concentrating the black liquor lignin by using a nanofiltration membrane to obtain a lignin liquid; the molecular weight of the nanofiltration membrane is 1000-8000, and the treatment conditions are 40-70°C and an inlet membrane pressure of 10-40 bar;

[0009] (3) adding a styrene-butadiene latex to the lignin liquid, stirring at 50-500 r / min for 5-20 min to obtain a composite emulsion;

[0010] (4) adding an inorganic acid to the composite emulsion for acid precipitation treatment, adjusting the pH value to 2.0-5.0, precipitating the composite rubber, and then using a plate-and-frame filter press to separate the composite rubber from the liquid, the pressing pressure of the plate-and-frame filter press being 10-20 kg, then washing with water at a temperature of 40-60°C, and hot air drying to obtain the lignin-styrene-butadiene rubber composite glue.

[0011] In the present application, first, a pre-filter is used to remove fiber impurities in the pulping black liquor, and the obtained fiber impurities are recycled to the papermaking section; then, a nanofiltration membrane is used to concentrate the black liquor lignin to extract lignin, and the alkali-containing filtrate produced by nanofiltration is recycled to the black liquor treatment section of the paper mill.

[0012] As a further scheme of the present application: in step (1), the pulping black liquor is at least one of dissolving pulp black liquor, soda pulping black liquor, and kraft pulping black liquor.

[0013] As a further scheme of the present application: in step (2), the solid content of the lignin liquid is 15-25%, and the density is 1.08-1.20 g / mL.

[0014] As a further scheme of the present application: in step (3), the amount of the lignin liquid used is 10-50% of the mass of the styrene-butadiene latex.

[0015] And / or, in step (3), the solid content of the styrene-butadiene latex is 20-40%.

[0016] As a further scheme of the present application: in step (4), the inorganic acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and the mass concentration of the inorganic acid is 10-30%.

[0017] And / or, in step (4), the temperature of the acid precipitation treatment is 40-60℃.

[0018] And / or, in step (4), the amount of water used for washing is 4-10 times the amount of the composite rubber used.

[0019] In another aspect of the present application, a lignin-styrene-butadiene rubber composite glue is provided, which is prepared by the above-mentioned method for preparing a lignin-styrene-butadiene rubber composite glue.

[0020] In a third aspect of the present application, the above-mentioned lignin-styrene-butadiene rubber composite glue is applied in rubber products, and the rubber products include the following components: the lignin-styrene-butadiene rubber composite glue containing 100 parts of styrene-butadiene rubber, 10-65 parts of white carbon black, 1-4 parts of stearic acid, 1-8 parts of zinc oxide, 1-6 parts of antioxidant N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine, 0.5-1.5 parts of accelerator N-(1,1-dimethylethyl)-2-benzothiazole sulfenamide, 2-5 parts of coupling agent bis-[gamma-(triethoxysilyl)propyl]tetrasulfide, 1-4 parts of accelerator N,N'-diphenylguanidine, 0.5-2 parts of sulfur, and 0.1-0.5 parts of anti-scorching agent N-cyclohexylthiophthalimide.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] This invention employs nanofiltration membrane separation to extract lignin from pulping black liquor. This process is highly efficient and clean, significantly reducing wastewater, waste gas, and waste residue generated during traditional lignin extraction, thus significantly lowering the difficulty and cost of waste treatment. Simultaneously, this method directly obtains high-purity liquid lignin, eliminating the need for further dissolution with alkalis or organic solvents, and allows for excellent liquid-liquid blending with styrene-butadiene rubber latex. This simplifies the preparation process of lignin-styrene-butadiene rubber composites, reduces production steps and additive consumption, effectively shortens the production cycle, and improves overall process efficiency and economy. Furthermore, based on the synergistic co-precipitation of liquid lignin and styrene-butadiene rubber latex, it fundamentally solves the problems of difficult dispersion and easy agglomeration of dry lignin in the rubber matrix, significantly improving the compatibility and uniformity of the composite rubber. The final lignin-styrene-butadiene rubber composite exhibits good mechanical properties and resistance to thermo-oxidative aging. Detailed Implementation

[0023] The present invention is further illustrated below by way of examples, but these examples do not limit the invention to the scope of the embodiments described. Experimental methods not specifically described in the following examples were performed according to conventional methods and conditions, or according to the product instructions. Furthermore, all reagents and raw materials used in the present invention are commercially available. In the embodiments and comparative examples of the present invention, the organic content of the pulping black liquor is 60-70%; the inorganic content is 30-40%; and lignin accounts for 25-35% of the solids in the pulping black liquor.

[0024] Example 1

[0025] The preparation method of lignin-styrene-butadiene rubber composite adhesive includes the following steps:

[0026] (1) A 5μm pre-filter was used to filter black liquor from caustic soda pulping with a solid content of 10%, a density of 1.04 g / mL, and a pH of 12.4.

[0027] (2) The treatment liquid was concentrated by ultrafiltration using a 1000 molecular weight nanofiltration membrane made of alkali-resistant polysulfone membrane. The treatment temperature was 40℃ and the feed pressure was 10 bar. The solid content of the concentrated liquid after treatment was 15% and the density was 1.10 g / mL.

[0028] (3) The solid content of the styrene-butadiene latex used is 20%.

[0029] (4) The lignin liquid is mixed with styrene-butadiene latex and stirred thoroughly. The stirring conditions are 50 r / min for 5 min and the amount of lignin liquid is 10% of the mass of styrene-butadiene latex.

[0030] (5) The pH of the composite emulsion system was adjusted by using hydrochloric acid with an acid concentration of 10%, and the pH after the reaction was controlled to be 2.0. The temperature of the system was controlled to be 40℃.

[0031] (6) A plate and frame filter press is used to separate the solid and liquid components of the mixture after adding acid, and the mixture is washed with clean water. The amount of water used for washing is 4 times that of the composite rubber, the washing temperature is 40°C, and the plate and frame pressing pressure is 10 kg.

[0032] (7) The composite adhesive is dried by hot air drying, and the volatile matter content is 3% after drying.

[0033] Example 2

[0034] The preparation method of lignin-styrene-butadiene rubber composite adhesive includes the following steps:

[0035] (1) A 10μm pre-filter was used to filter the dissolving black liquor with a solid content of 15%, a density of 1.07g / mL, and a pH of 12.8.

[0036] (2) The treatment liquid was concentrated by ultrafiltration using a 4000 molecular weight nanofiltration membrane made of alkali-resistant polysulfone membrane. The treatment temperature was 60℃ and the feed pressure was 25 bar. The solid content of the concentrated liquid after treatment was 20% and the density was 1.15 g / mL.

[0037] (3) The solid content of the styrene-butadiene latex used is 30%.

[0038] (4) The lignin liquid was mixed with styrene-butadiene latex and stirred thoroughly. The stirring conditions were 200 r / min for 10 min, and the amount of lignin liquid was 30% of the mass of styrene-butadiene latex.

[0039] (5) The pH of the composite emulsion system was adjusted by sulfuric acid with an acid concentration of 20%, the pH after the reaction was controlled to be 3.5, and the temperature of the system was controlled to be 50℃.

[0040] (6) A plate and frame filter press is used to separate the solid and liquid components of the mixture after adding acid, and the mixture is washed with clean water. The amount of water used for washing is 7 times that of the composite rubber, the washing temperature is 50°C, and the plate and frame pressing pressure is 15 kg.

[0041] (7) The composite adhesive is dried by hot air drying, and the volatile matter content is 2% after drying.

[0042] Example 3

[0043] The preparation method of lignin-styrene-butadiene rubber composite adhesive includes the following steps:

[0044] (1) A 20μm pre-filter was used to filter sulfate pulping black liquor with a solid content of 20%, a density of 1.08g / mL, and a pH of 12.6.

[0045] (2) The treatment liquid was concentrated by ultrafiltration using an 8000 molecular weight nanofiltration membrane made of alkali-resistant polysulfone membrane. The treatment temperature was 70℃ and the feed pressure was 40 bar. The solid content of the concentrated liquid after treatment was 25% and the density was 1.15 g / mL.

[0046] (3) The solid content of the styrene-butadiene latex used is 40%.

[0047] (4) The lignin liquid was mixed with styrene-butadiene latex and stirred thoroughly. The stirring conditions were 500 r / min for 20 min, and the amount of lignin liquid was 50% of the mass of styrene-butadiene latex.

[0048] (5) Phosphoric acid was used to adjust the pH of the composite emulsion system. The acid concentration was 30%, the pH after the reaction was controlled to be 5.0, and the temperature of the system was controlled to be 60℃.

[0049] (6) A plate and frame filter press is used to separate the solid and liquid components of the mixture after adding acid, and the mixture is washed with clean water. The amount of water used for washing is 10 times that of the composite rubber, the washing temperature is 60℃, and the plate and frame pressing pressure is 20 kg.

[0050] (7) The composite adhesive is dried by hot air drying, and the volatile matter content is 1% after drying.

[0051] Comparative Example 1

[0052] Liquid lignin and an equal amount of dry lignin powder were added during the rubber compounding process, and a styrene-butadiene rubber compounding formula was used for compounding, vulcanization, and testing.

[0053] Comparative Example 2

[0054] The only difference from Example 1 is that the nanofiltration membrane operation in step (2) is omitted.

[0055] Comparative Example 3

[0056] The only difference from Example 1 is that in step (2), the processing temperature is 20°C.

[0057] Comparative Example 4

[0058] The only difference from Example 1 is that in step (3), the solid content of styrene-butadiene latex is 10%.

[0059] Comparative Example 5

[0060] The only difference from Example 1 is that in step (4), the stirring speed is 1000 r / min.

[0061] Comparative Example 6

[0062] The only difference from Example 1 is that in step (5), the temperature of the system is controlled at 20°C.

[0063] Comparative Example 7

[0064] The only difference from Example 1 is that in step (6), the washing temperature is 20°C.

[0065] Application Examples

[0066] The products of Examples 1-3 and Comparative Examples 1-7 were mixed according to the following formula: by weight, 100 parts of styrene-butadiene rubber lignin-styrene-butadiene rubber composite, 40 parts of silica, 2 parts of stearic acid, 4 parts of zinc oxide, 3 parts of antioxidant N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine, 1 part of accelerator N-(1,1-dimethylethyl)-2-benzothiazole sulfinamide, 4 parts of coupling agent bis-[γ-(triethoxysilyl)propyl]tetrasulfide, 2 parts of accelerator N,N′-diphenylguanidine, 1.4 parts of sulfur, and 0.3 parts of scorch inhibitor N-cyclohexylthiophthalimide.

[0067] After mixing and vulcanization, physical and mechanical properties were tested. Then, the vulcanized compound was subjected to thermo-oxidative aging treatment at 70℃ in air for 72 hours, followed by further testing of its relevant physical and mechanical properties. Additionally, an equal amount of styrene-butadiene rubber (SBR) as the lignin-styrene-butadiene rubber composite in the compounding formulation was used for mixing, vulcanization, and testing as a reference sample. Specifically, the testing methods followed GB / T 528-2009. The test results are shown in Table 1. The average membrane flux refers to the volume of sample passing through a unit area per unit time; for example, the filtrate volume passing through the membrane device in 1 hour is 4.1 L, and the small-scale membrane area is 0.2 m². 2 The average membrane flux is calculated to be 4.1 / (0.2*1) = 20.5 L / (m²). 2 ·h), the moisture content of the composite adhesive is determined by taking a certain amount of sample in a 105℃ oven, drying it for 2 hours, and calculating the weight loss rate, which is the moisture content.

[0068] Table 1

[0069]

[0070]

[0071] As shown in Table 1 and the process flow, the lignin-styrene-butadiene rubber composite rubber prepared by the method of this invention has a simpler production process, does not involve organic solvents, significantly reduces wastewater and waste gas emissions, and has a high degree of continuous and automated operation, effectively solving the problem of lignin dispersion uniformity in the composite rubber. After mixing, the composite rubber exhibits superior mechanical properties and good resistance to thermo-oxidative aging. Among these, Example 2 achieves the best overall performance in key indicators such as mechanical properties, anti-aging properties, and process efficiency.

[0072] This invention achieves efficient resource utilization of pulping black liquor, reducing exhaust gas pollution from black liquor combustion and realizing high-value transformation of waste. By using lignin to replace part of the carbon black, it promotes the substitution of petrochemical-based carbon with bio-based carbon. Simultaneously, leveraging lignin's inherent UV resistance and anti-aging properties, it endows rubber products with more functional properties and reduces the amount of some additives used. This method organically combines black liquor treatment with rubber production, promoting cross-industry collaboration between pulping and papermaking and the rubber industry, and improving the level of comprehensive resource utilization. The wet blending process of lignin and styrene-butadiene rubber latex effectively solves the problem of lignin dispersion in rubber. By replacing traditional petrochemical-based carbon with bio-based carbon materials, the lignin-styrene-butadiene rubber composite prepared by this invention exhibits excellent comprehensive performance and significant environmental benefits and application prospects.

[0073] Finally, it should be noted that in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0074] Although this disclosure has been described above through specific embodiments, it should be understood that those skilled in the art can devise various modifications, improvements, or equivalents to this disclosure within the spirit and scope of the appended solutions. Such modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed in this disclosure.

Claims

1. A method for preparing a lignin-styrene-butadiene rubber composite adhesive, characterized in that, Specifically, the following steps are included: (1) The pulping black liquor is treated with a 5-20 μm pre-filter to obtain black liquor lignin; the solid content of the pulping black liquor is 10-20%, the density is 1.03-1.10 g / mL, and the pH value is 11.0-13.5; (2) The black liquor lignin is concentrated using a nanofiltration membrane to obtain lignin liquid; the molecular weight of the nanofiltration membrane is 1000-8000, the processing conditions are 40-70℃, and the inlet pressure is 10-40 bar. (3) Add styrene-butadiene latex to the lignin liquid and stir at 50-500 r / min for 5-20 min to obtain a composite emulsion; (4) Add inorganic acid to the composite emulsion for acid precipitation treatment, adjust the pH value to 2.0-5.0, and after the composite rubber is precipitated, use a plate and frame filter press to separate the solid and liquid of the composite rubber. The pressing pressure of the plate and frame filter press is 10-20 kg, and then wash with water at a temperature of 40-60℃. Dry with hot air to obtain the lignin-styrene-butadiene rubber composite.

2. The method for preparing lignin-styrene-butadiene rubber composite adhesive according to claim 1, characterized in that, In step (1), the pulping black liquor is at least one of dissolving pulping black liquor, caustic soda pulping black liquor, and sulfate pulping black liquor.

3. The method for preparing lignin-styrene-butadiene rubber composite adhesive according to claim 1, characterized in that, In step (2), the solid content of the lignin liquid is 15-25%, and the density is 1.08-1.20 g / mL.

4. The method for preparing lignin-styrene-butadiene rubber composite adhesive according to claim 1, characterized in that, In step (3), the amount of lignin liquid used is 10-50% of the mass of the styrene-butadiene latex; And / or, in step (3), the solid content of the styrene-butadiene latex is 20-40%.

5. The method for preparing lignin-styrene-butadiene rubber composite adhesive according to claim 1, characterized in that, In step (4), the inorganic acid is at least one of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, and the mass concentration of the inorganic acid is 10-30%. And / or, in step (4), the temperature of the acid precipitation treatment is 40-60°C; And / or, in step (4), the amount of water used for washing is 4 to 10 times the amount of composite rubber used.

6. A lignin-styrene-butadiene rubber composite adhesive, which is prepared by the method of preparing the lignin-styrene-butadiene rubber composite adhesive according to claims 1 to 5.

7. The lignin-styrene-butadiene rubber composite adhesive according to claim 6, characterized in that, The volatile matter content of the lignin-styrene-butadiene rubber composite is less than or equal to 3%.

8. The application of the lignin-styrene-butadiene rubber composite as described in claims 6-7 in rubber products, characterized in that, The rubber product comprises the following components by weight: 100 parts of styrene-butadiene rubber (SBR) composite rubber, 10-65 parts of silica, 1-4 parts of stearic acid, 1-8 parts of zinc oxide, 1-6 parts of antioxidant N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine, 0.5-1.5 parts of accelerator N-(1,1-dimethylethyl)-2-benzothiazole sulfinamide, 2-5 parts of coupling agent bis-[γ-(triethoxysilyl)propyl]tetrasulfide, 1-4 parts of accelerator N,N′-diphenylguanidine, 0.5-2 parts of sulfur, and 0.1-0.5 parts of scorch inhibitor N-cyclohexylthiophthalimide.

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