Modified liquid reclaimed rubber as well as rubber composition and preparation method thereof

Abstract

The invention provides modified liquid reclaimed rubber as well as a rubber composition and a preparation method thereof, and the modified liquid reclaimed rubber is prepared from the following raw materials in parts by weight: 70-90 phr of tire waste rubber powder, 0.5-8 phr of maleic acid modified resin, 1-20 phr of modified lignosulfonate and 0.5-15 phr of a processing aid, an anti-aging and anti-reduction type rubber composition is prepared according to the liquid reclaimed rubber and is prepared from 10 to 50 phr of modified liquid reclaimed rubber, 50 to 90 phr of an anti-aging agent and 5 to 10 phr of a dispersing aid. According to the liquid reclaimed rubber prepared by the preparation method disclosed by the invention, the maleic acid modified resin and the modified lignosulfonate are used as reinforcing agents to prepare the anti-reduction type modified liquid reclaimed rubber, and the environmental pollution of the prepared rubber is reduced; the anti-aging agent is added, so that the anti-aging performance of the rubber is also remarkably improved, the lasting time is long and stable, and the service life of the rubber is prolonged.

Description

Technical Field

[0001] This invention relates to the field of reclaimed rubber manufacturing technology, and more particularly to the field of manufacturing liquid reclaimed rubber. Background Technology

[0002] Reclaimed rubber, as an environmentally friendly material, offers significant economic and environmental benefits through the reuse of waste rubber. Liquid reclaimed rubber is a specialty reclaimed rubber product pioneered by our company. It is a novel and important raw material for reclaimed rubber. Liquid reclaimed rubber is a material with a certain degree of fluidity at room temperature, especially at rubber processing temperatures, and has good processing properties. Utilizing the remaining functions of liquid reclaimed rubber is the focus of this project.

[0003] Liquid reclaimed rubber breaks down the three-dimensional cross-linked network of rubber to form flowable oligomers, combining the properties of plasticizers and rubber, thus solving the compatibility problem between traditional reclaimed rubber and raw rubber. Traditional reclaimed rubber, due to its incomplete residual vulcanization network, is susceptible to main chain breakage caused by oxygen, ozone, and heat during processing and use, leading to problems such as decreased tensile strength and cracking. Traditional reclaimed rubber also carries the risk of reduction; incompletely removed metal ions and residual vulcanization accelerators in the reclaimed rubber may trigger reduction reactions, accelerating material degradation.

[0004] The conventional antioxidants used in the rubber formulation mentioned in patent CN119144070A have antioxidant properties that decay over time, produce toxic substances during production or degradation, and have poor oil resistance. The liquid reclaimed rubber preparation method mentioned in patent CN119931149A uses lignin as a functional agent, and the prepared rubber has insufficient anti-aging and anti-reduction properties. Summary of the Invention

[0005] This invention addresses the shortcomings of current functional additives in rubber, particularly the poor dispersion of added antioxidants and the premature consumption of effective components during rubber compounding due to heat and oxidation, resulting in insufficient anti-aging and anti-reduction properties of antioxidants. It provides a modified liquid reclaimed rubber composition that improves antioxidant dispersion and enhances the retention rate of effective antioxidant components. Maleic acid-modified resin is used as an anti-reduction agent to significantly improve the anti-reduction properties of the liquid reclaimed rubber; furthermore, maleic acid-modified resin is a low-toxicity, biodegradable, and environmentally friendly material, which can serve as an anti-reduction agent and reduce environmental pollution.

[0006] The modified liquid reclaimed rubber and antioxidant composition provided by this invention can replace conventional antioxidants, anti-reduction additives, and also replace some plasticizers and softeners, thereby improving the processing performance of the rubber composition.

[0007] To prepare a modified liquid rubber composition, the present invention also provides a preparation method that can prepare an anti-aging and anti-reduction liquid reclaimed rubber composition.

[0008] To achieve the above objectives, this invention provides a modified liquid reclaimed rubber comprising the following parts by weight: 70-90 phr of waste tire rubber powder, 0.5-8 phr of maleic acid-modified resin, and 1-20 phr of modified lignin sulfonate. The waste rubber powder, maleic acid-modified resin, and modified lignin sulfonate are blended together. Through physical interaction, the lignin sulfonate disperses the three components in the system, the sulfonic acid groups ensure uniform distribution of the rubber powder within the system, reducing agglomeration, and the maleic acid-modified resin penetrates the pores of the rubber powder. Simultaneously, the double bonds in the maleic acid groups undergo a DA grafting reaction with the double bonds in the rubber, improving the interfacial chemical properties of the rubber.

[0009] In terms of chemical interaction, the bisphenol structure in lignin sulfonate combines with rubber molecules to generate ultra-large hindered phenol molecules, which can enhance the antioxidant and reduction resistance of liquid reclaimed rubber. The anhydride groups in maleic acid modified resin and the hydroxyl and sulfonic acid groups in lignin sulfonate can synergistically exert a reduction-resistant effect. The anhydride groups react with unsaturated double bonds or free radicals in the rubber matrix to form stable chemical bonds, increasing chemical inertness and making it less susceptible to reduction. The hydroxyl and sulfonic acid groups in lignin sulfonate can undergo reduction reactions, protecting the rubber compound.

[0010] As a preferred option, the raw materials, by weight, include: 80-90 phr of waste tire rubber powder, 5-8 phr of maleic acid modified resin, 10-20 phr of modified lignin sulfonate, and 0.5-15 phr of processing aids.

[0011] Preferably, the maleic acid modified resin is any one of maleic acid modified terpene resin, maleic acid modified DCPD resin, or maleic acid grafted C5-C9 resin. The anhydride groups in the maleic acid modified resin can react with unsaturated double bonds or free radicals in the rubber matrix to form stable chemical bonds, reducing oxidative degradation and delaying aging. The presence of the anhydride groups enhances the resin's chemical inertness, making it less susceptible to reduction at reducing temperatures and maintaining stable performance. The modified resin can react with vulcanization accelerators, peroxides, etc., optimizing the vulcanization network and reducing the damage to the vulcanization structure caused by reducing substances. Maleic acid modified resin can increase the viscosity and cohesive strength of liquid reclaimed rubber, improve processing fluidity, and enhance interfacial bonding with fillers. The anhydride, being a polar group, allows for better compatibility with the rubber matrix and fillers, reducing phase separation.

[0012] Preferably, the processing aid is any one of aromatic oils, naphthenic oils, paraffin oils, phthalates, tall oils, and silicone oils.

[0013] Preferably, the composition comprises the following raw materials by weight: 10-50 phr of modified liquid reclaimed rubber, 50-90 phr of antioxidant, and 5-10 phr of dispersant. The modified liquid reclaimed rubber and a large proportion of antioxidant allow this rubber composition to replace, in equal amounts, traditional pure antioxidants. Simultaneously, the premixed liquid reclaimed rubber and antioxidant work synergistically, producing two effects: firstly, after this rubber composition replaces the antioxidant, the antioxidant is more evenly dispersed in the rubber, thus better exerting its function; secondly, it can reduce the premature loss of pure antioxidants caused by oxygen and temperature during rubber compounding. The anti-aging and anti-reduction liquid reclaimed rubber composition obtained in this project can be used as an antioxidant masterbatch.

[0014] Preferably, the antioxidant is any one or more of antioxidant RD, antioxidant 6PPD, antioxidant DTPD, antioxidant 4030, antioxidant 4010NA, and antioxidant 1068.

[0015] Preferably, the dispersing agent is any one of carbon black, silica, lignin, or graphite / carbon fiber.

[0016] The present invention also provides a method for preparing a rubber composition of modified liquid reclaimed rubber, comprising the following steps: S1. Waste tire rubber powder is washed, desulfurized, and dried to obtain rubber powder with a particle size of 20-100 mesh. Waste tire rubber powder, maleic acid modified resin, and modified lignin sulfonate are added to a high-speed mixing tank and mixed to obtain a mixture.

[0017] S2, the mixture is transferred to a low-speed mixing tank and continuously stirred to obtain premixed rubber powder for continuous desulfurization.

[0018] S3, the premixed rubber powder is transferred to a desulfurization extruder, and after desulfurization, modified liquid reclaimed rubber is obtained.

[0019] S4, a cooled modified liquid reclaimed rubber, blended with an antioxidant.

[0020] S5, the blend and dispersant are co-extruded to obtain a rubber composition of modified liquid reclaimed rubber.

[0021] Preferably, the stirring speed in step S1 is 100-2000 rpm and the stirring time is 5-20 minutes; the stirring speed in step S2 is 20-100 rpm and the stirring is continuous.

[0022] Preferably, in step S3, the desulfurization temperature is 250–400°C; in step S4, the temperature is cooled to 50–80°C.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The modified liquid reclaimed rubber prepared by the present invention is a modified liquid reclaimed rubber with added maleic acid modified resin and modified lignin sulfonate. Maleic acid modified resin and modified lignin sulfonate have synergistic anti-reduction advantages, which improve the aging resistance and anti-reduction properties of the liquid reclaimed rubber, and significantly improve its dynamic stability. Maleic acid modified resin and modified lignin sulfonate can also enhance interfacial bonding and improve rubber dispersibility, reducing the use of dispersants in the preparation process.

[0024] A high-proportion antioxidant and modified liquid reclaimed rubber were blended to prepare an anti-aging and anti-reduction type liquid reclaimed rubber composition, which directly replaces traditional antioxidants. Compared with traditional antioxidants, the product of this invention has better dispersibility, resulting in more uniform dispersion of the antioxidant at the same dosage and better anti-aging effect. Secondly, it can reduce the premature consumption of antioxidants due to heat and oxygen during the traditional rubber mixing process, thus extending the antioxidant's action period. The liquid rubber composition prepared in this project has better compatibility with polymer materials, better exerting the function of the antioxidant itself.

[0025] Another advantage of this technology is that it simplifies the preparation method and makes it easy to produce. Detailed Implementation

[0026] The present application will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0027] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; the parts in the following embodiments refer to parts by weight.

[0028] General Implementation Examples:

[0029] Composition of modified liquid reclaimed rubber: 70-90 phr of waste tire rubber powder, 0.5-8 phr of maleic acid modified resin, 1-20 phr of modified lignin sulfonate, and 0.5-10 phr of processing aids. Rubber composition: 10-50 phr of modified liquid reclaimed rubber, 50-90 phr of antioxidant, and 5-10 phr of dispersant.

[0030] A method for preparing modified liquid reclaimed rubber: S1. Wash, desulfurize, and dry the waste tire rubber powder to obtain rubber powder with a particle size of 20-100 mesh; heat to 60-80℃ to soften the maleic acid modified resin, stir until it has good fluidity, add the waste tire rubber powder, maleic acid modified resin and modified lignin sulfonate into a high-speed mixing tank and stir to mix at a stirring speed of 100-2000 rpm for 5-20 minutes to obtain a mixture; S2, transfer the stirred mixture into a low-speed mixing tank and stir at a speed of 20-100 rpm to obtain premixed rubber powder. S3, the premixed rubber powder is fed into a desulfurization extruder for desulfurization; after desulfurization, modified liquid reclaimed rubber is obtained, with a desulfurization temperature of 250-400℃; S4, Cool the modified liquid reclaimed rubber to 50-80℃, add an antioxidant and blend to obtain a blend; S5, the blend and dispersant are co-extruded to obtain a rubber composition of modified liquid reclaimed rubber.

[0031] Example 1

[0032] Composition of modified liquid reclaimed rubber: 80 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, 5 phr of modified lignin sulfonate, and 10 phr of naphthenic oil. Rubber composition: 17 phr of modified liquid reclaimed rubber, 75 phr of antioxidant RD, and 8 phr of carbon black N330.

[0033] Preparation method: First, the waste tire rubber powder is cleaned, desulfurized and dried to obtain rubber powder with a particle size of 20-100 mesh; then, the maleic acid modified resin is heated to 60-80℃ to soften it, and stirred until it has good fluidity. The waste tire rubber powder, maleic acid modified resin and modified lignin sulfonate are added to a high-speed mixing tank and stirred and mixed at a stirring speed of 800 rpm for 10 minutes to obtain a mixture.

[0034] The mixed material is transferred to a low-speed mixing tank and stirred continuously at a speed of 50 rpm to prepare the premixed adhesive powder.

[0035] The premixed rubber powder was fed into a desulfurization extruder and liquefied to obtain modified liquid reclaimed rubber. The desulfurization temperature was 360℃ and the desulfurization time was 10 min.

[0036] The modified liquid reclaimed rubber is cooled to 70°C in an extruder, an antioxidant is added, and extrusion and compounding continue.

[0037] Dispersants are added to the aforementioned antioxidant blends.

[0038] The aforementioned blend is extruded to obtain a rubber composition of modified liquid reclaimed rubber.

[0039] This formulation has the following characteristics: The amount of reclaimed rubber powder used in this liquid reclaimed rubber formulation is relatively low, and the overall cost may be relatively low. However, the mechanical properties of the product need to be verified to ensure they meet the requirements. The amount of maleic acid modified resin and modified lignin sulfonate is relatively small, so the flexibility and filling effect of the product may be relatively weak, and the resistance to reduction may also be low.

[0040] Example 2 Composition of modified liquid reclaimed rubber: 70 phr of waste tire rubber powder, 6 phr of maleic acid modified DCPD resin, 12 phr of modified lignin sulfonate, and 12 phr of naphthenic oil. Rubber composition: 17 phr of modified liquid reclaimed rubber, 75 phr of antioxidant RD, and 8 phr of carbon black N330.

[0041] The preparation method is the same as in Example 1.

[0042] In this formula, the amounts of waste tire rubber powder, maleic acid modified resin, and modified lignin sulfonate are in the middle range, resulting in a relatively balanced overall performance, making it suitable for rubber products with moderate performance requirements. The amounts of maleic acid modified resin and highly dispersive composite resorcinol are moderate, providing a certain degree of modification effect and stability.

[0043] Example 3 Composition of modified liquid reclaimed rubber: 70 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, 15 phr of modified lignin sulfonate, and 10 phr of naphthenic oil. Rubber composition: Same as in Example 1.

[0044] The preparation method is the same as in Example 1.

[0045] This formulation features: the amount of waste tire rubber powder used in this formulation reaches the upper limit, resulting in a higher proportion of the product's main component, which may improve the product's wear resistance and aging resistance; the amount of maleic acid modified resin and lignin sulfonate used can achieve a good balance of overall performance, making it suitable for rubber products with high performance requirements.

[0046] Example 4 Composition of modified liquid reclaimed rubber: 75 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, 10 phr of modified lignin sulfonate, and 10 phr of naphthenic oil. Rubber composition: Same as in Example 1.

[0047] The preparation method is the same as in Example 1.

[0048] This formulation has the following characteristics: The amount of reclaimed rubber powder used in this formulation is slightly lower, but by increasing the amount of maleic acid modified resin and naphthenic oil, the performance deficiency can be compensated to a certain extent, while maintaining good flexibility and processing performance.

[0049] Example 5 Composition of modified liquid reclaimed rubber: 63 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, 20 phr of modified lignin sulfonate, and 12 phr of naphthenic oil. Rubber composition: Same as in Example 1.

[0050] The preparation method is the same as in Example 1.

[0051] Features of this formula: The amount of reclaimed rubber powder in this formula is close to the upper limit, resulting in strong main properties of the product; by adjusting the amount of maleic acid modified resin, modified lignin sulfonate, and naphthenic oil, a good balance of comprehensive performance can be achieved, making it suitable for rubber products with high performance requirements.

[0052] Example 6 Composition of modified liquid reclaimed rubber: 52 phr of waste tire rubber powder, 8 phr of maleic acid modified DCPD resin, 25 phr of modified lignin sulfonate, and 15 phr of tall oil. Rubber composition: Same as in Example 1.

[0053] The preparation method is the same as in Example 1.

[0054] This formulation features tall oil as a processing aid. Tall oil is a natural plant-derived additive and an environmentally friendly material. It has softening, dispersing, and mild sulfurizing activity, high viscosity, and poor flowability at low temperatures.

[0055] Example 7 Composition of liquid reclaimed rubber: Modified liquid reclaimed rubber composition: 57 phr of waste tire rubber powder, 8 phr of maleic acid modified DCPD resin, 20 phr of modified lignin sulfonate, and 15 phr of aromatic oil. Rubber composition: Same as in Example 1.

[0056] The preparation method is the same as in Example 1.

[0057] The characteristics of this formulation are: the processing aid used in this formulation is aromatic oil. Aromatic oil has strong polarity, which significantly reduces the hardness of the rubber compound and improves its fluidity. The aromatic ring structure can penetrate the vulcanization network and help break the SS bond, but it has poor environmental performance.

[0058] Example 8 Composition of modified liquid reclaimed rubber: 57 phr of waste tire rubber powder, 8 phr of maleic acid modified DCPD resin, 20 phr of modified lignin sulfonate, and 15 phr of tall oil. Rubber composition: Same as in Example 1.

[0059] The preparation method is the same as in Example 1.

[0060] This formulation features tall oil as a processing aid. Tall oil is a natural plant-derived, environmentally friendly material that combines softening, dispersing, and mild sulfurizing activity. It has high viscosity and poor flowability at low temperatures.

[0061] Example 9 Composition of modified liquid reclaimed rubber: 57 phr of waste tire rubber powder, 8 phr of maleic acid modified terpene resin, 20 phr of modified lignin sulfonate, and 15 phr of naphthenic oil. Rubber composition: Same as in Example 1.

[0062] The preparation method is the same as in Example 1.

[0063] This formulation features: maleic acid-modified terpene resin, which contains a natural terpene skeleton and medium- to high-polarity carboxyl groups. It can soften the adhesive while improving self-adhesion, reducing the risk of brittleness of reclaimed rubber at low temperatures, and is an environmentally friendly material suitable for green products.

[0064] Example 10 Composition of modified liquid reclaimed rubber: 57 phr of waste tire rubber powder, 8 phr of maleic acid modified C5 resin, 20 phr of modified lignin sulfonate, and 15 phr of naphthenic oil. Rubber composition: Same as in Example 1.

[0065] The preparation method is the same as in Example 1.

[0066] This formulation features: maleic acid modified C5 resin, which has a linear C5 chain structure and intermediate carboxyl groups, is inexpensive, and has good compatibility with hydrocarbon rubbers; it reduces melt viscosity, making it easy to inject or extrude, provides general-purpose thickening, and has a reinforcing effect on tensile strength.

[0067] The liquid reclaimed adhesives used in the following examples all adopted the formulation of the liquid reclaimed adhesive from Example 3, and the preparation method followed the preparation method of Example 1.

[0068] Example 11 Rubber composition: 22 phr of modified liquid reclaimed rubber, 70 phr of antioxidant RD, and 8 phr of carbon black N330.

[0069] The composition of this rubber composition, with moderate additions of antioxidants and modified liquid reclaimed rubber, is expected to produce moderate performance.

[0070] Example 12 Rubber composition: 35 phr modified liquid reclaimed rubber, 60 phr antioxidant RD, 5 phr carbon black N330.

[0071] The composition of this rubber composition contains a relatively large amount of modified liquid reclaimed rubber and a relatively small amount of antioxidant, so its resistance to reduction is expected to be low.

[0072] Example 13 Rubber composition: 24 phr modified liquid reclaimed rubber, 70 phr antioxidant RD, 6 phr carbon black N330.

[0073] Example 14 Rubber composition: 11 phr of modified liquid reclaimed rubber, 80 phr of antioxidant RD, and 9 phr of carbon black N330.

[0074] The composition of this rubber compound contains the largest amounts of modified liquid reclaimed rubber and antioxidants, and its performance is expected to be the best.

[0075] Comparative Example 1 Liquid reclaimed rubber composition: 85 phr of waste tire rubber powder, 5 phr of modified lignin sulfonate, and 10 phr of naphthenic oil. The composition of the rubber composition is the same as that in Example 1.

[0076] The preparation method is the same as in Example 1.

[0077] This comparative example lacks maleic acid-modified resin, resulting in decreased tensile properties, aging resistance, and reduction resistance.

[0078] Comparative Example 2 Composition of liquid reclaimed rubber: 85 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, and 10 phr of naphthenic oil. The composition of the rubber composition is the same as that in Example 1.

[0079] The preparation method is the same as in Example 1.

[0080] The comparative ratio lacks modified lignin sulfonate, which may reduce the crosslinking stability, reduction resistance, and dispersibility of the liquid reclaimed rubber.

[0081] Comparative Example 3 Composition of modified liquid reclaimed rubber: 80 phr of waste tire rubber powder, 5 phr of maleic acid modified DCPD resin, 5 phr of modified lignin sulfonate, and 10 phr of naphthenic oil. Rubber composition: 17 phr of modified liquid reclaimed rubber, 75 phr of antioxidant RD, and 8 phr of silica.

[0082] The preparation method is the same as in Example 1.

[0083] The comparative example replaced the dispersant with silica, which can synergistically improve the resistance to reduction.

[0084] Comparative Example 4 The composition ratio of the liquid reclaimed adhesive is the same as in Example 1; Rubber composition: 17 phr modified liquid reclaimed rubber, 75 phr antioxidant RD, 8 phr graphite / carbon fiber.

[0085] The preparation method is the same as in Example 1.

[0086] This comparative example uses graphite / carbon fiber as a dispersing agent. Graphite has excellent electrical and thermal conductivity, which can improve the heat resistance and electrical conductivity of rubber. Graphite also has lubricity and wear resistance, which can also enhance the wear resistance of rubber. Carbon fiber can significantly improve the tensile strength, stiffness and impact resistance of materials. Carbon fiber can be customized in terms of performance, and different properties of rubber can be improved by adding different carbon fibers. Graphite / carbon fiber can be combined to synergistically improve the wear resistance and tear resistance of rubber.

[0087] Comparative Example 5 The composition ratio of the liquid reclaimed adhesive is the same as in Example 1: Rubber composition: 17 phr modified liquid reclaimed rubber, 75 phr antioxidant 6 PPD, 10 phr naphthenic oil.

[0088] The preparation method for this comparative example is the same as that for Example 1.

[0089] Comparative Example 6 The composition ratio of the liquid reclaimed adhesive is the same as in Example 1: Rubber composition: 17 phr modified liquid reclaimed rubber, 75 phr antioxidant DTPD, and 10 phr naphthenic oil.

[0090] The preparation method for this comparative example is the same as that for Example 1.

[0091] Table 1. Liquid Reclaimed Rubber Raw Materials for Examples 1-9

[0092] Table 2. Raw material list for rubber compositions in Examples 10-13 Name / Raw Material Modified liquid reclaimed rubber (PHR) Anti-aging agent RD (phr) Carbon black (Phr) Example 11 22 70 8 Example 12 35 60 5 Example 13 24 70 6 Example 14 11 80 9

[0093] Table 3. Raw material list for liquid reclaimed rubber in Comparative Examples 1-4

[0094] Samples of the products from the comparative and example examples were used to replace antioxidant RD in rubber formulations for testing of anti-aging and anti-reduction properties. The strength of the rubber's anti-aging properties was verified by the retention rate of tensile strength, elongation at break, and decrease rate of mechanical properties after hot air aging (70°C × 72h), and the strength of the rubber's reduction properties was verified by the decrease rate of Mooney viscosity.

[0095] Table 4 shows the test results of the rubber's anti-aging and anti-reduction properties in Examples 1-9. Name / Testing Items Tensile strength retention Elongation at break retention mechanical property degradation rate Mooney viscosity reduction rate Example 1 72％ 90％ 20％ 23％ Example 2 76％ 85％ 18％ 20％ Example 3 87％ 80％ 12％ 15％ Example 4 83％ 88％ 14％ 17％ Example 5 81％ 77％ 10％ 14％ Example 6 90％ 89％ 7％ 12％ Example 7 91％ 75％ 9％ 10％ Example 8 88％ 74％ 11％ 14％ Example 9 85％ 76％ 14％ 16％ Example 10 84％ 76％ 15％ 18％

[0096] Table 4 shows that Example 7 has the best anti-aging and anti-reduction properties. Examples 1-5 are formulations with the same components but different ingredient ratios. The more modified sodium lignosulfonate added, the higher the anti-reduction properties, the higher the dispersibility, and the better the mechanical strength. Example 1 has a lower proportion of maleic acid modified resin and modified lignosulfonate, resulting in lower performance. Examples 3 and 6-8 use different processing aids. Naphthenic oil is mainly used as a physical softener, which reduces intermolecular forces by penetrating the rubber powder and assists in desulfurization. Aromatic oil is also a physical softener with high polarity and strong penetrability, excellent compatibility with rubber, and is also a physical softener, but it has a high PAH content. Tall oil is mainly composed of rosin acid, fatty acids, and resin acids, containing weakly acidic functional groups, and has both acid catalysis and physical softening properties. It also contains unsaturated fatty acids that crosslink with rubber.

[0097] The comparison between Examples 9, 10, and 3 compares the effects of maleic acid-modified DCPD resin, maleic acid-modified terpene resin, and maleic acid-modified C5 resin on rubber processing properties: Maleic acid-modified DCPD resin's main chain is dominated by cyclic single bonds with low double bond residue; maleic acid-modified terpene resin's main chain contains linear isoprene units, exhibiting higher flexibility than DCPD and moderate thermal stability; maleic acid-modified C5 resin has more aliphatic segments, high flexibility, and low thermal decomposition temperature; maleic acid-modified DCPD resin, due to its numerous cyclic structures and few double bonds in the main chain, exhibits the best resistance to reduction due to its strong molecular chain rigidity and good compatibility with rubber, followed by maleic acid-modified terpene resin; maleic acid-modified C5 resin, due to its numerous double bonds and high main chain flexibility, exhibits relatively poor resistance to reduction.

[0098] Table 5. Test results of rubber anti-aging and anti-reduction properties in Examples 11-14. Name / Testing Items Tensile strength retention Elongation at break retention mechanical property degradation rate Mooney viscosity reduction rate Example 11 84％ 81％ 12％ 11％ Example 12 79％ 74％ 16％ 6％ Example 13 88％ 85％ 10％ 8％ Example 14 92％ 89％ 7％ 14％

[0099] As shown in Table 5, Examples 11-14 were designed based on the liquid reclaimed rubber formulation of Example 3, with changes to the raw material ratios of the rubber composition. Experimental results show that the rubber in Example 14 exhibits stronger anti-aging properties, and the higher the proportion of liquid reclaimed rubber within a certain range, the more effective the functional reinforcement. Example 12 demonstrates the best anti-reduction properties.

[0100] Table 6. Test results of rubber anti-aging and anti-reduction properties in Examples 1 and Comparative Examples 1-4. Name / Testing Items Tensile strength retention Elongation at break retention mechanical property degradation rate Mooney viscosity reduction rate Example 1 72％ 90％ 20％ 23％ Comparative Example 1 40％ 39％ 31％ 37％ Comparative Example 2 36％ 29％ 34％ 42％ Comparative Example 3 76％ 69％ 26％ 18％ Comparative Example 4 64％ 59％ 24％ 29％ Comparative Example 5 73％ 91％ 19％ 24％ Comparative Example 6 72％ 89％ 21％ 22％

[0101] As shown in Table 6, compared with Comparative Example 1, the liquid reclaimed rubber lacked maleic acid modified resin. Maleic acid modified resin has the functions of thickening and plasticizing, and can improve the dispersibility and processing performance of the rubber compound. Its absence leads to uneven dispersion of carbon black filler, forming local concentration points and accelerating oxidation. The antioxidant groups in maleic acid modified resin can synergistically delay oxidation with carbon black or naphthenic oil. Maleic acid modified resin can participate in the vulcanization reaction to enhance the crosslinking density and improve the reduction resistance. After its absence, the rubber compound is prone to swelling or structural damage in a reducing environment. Therefore, the anti-aging properties of rubber lacking maleic acid modified resin are significantly reduced, and the reduction resistance is also weakened.

[0102] Compared with Example 1, the absence of modified lignin sulfonate leads to a decrease in the crosslinking density of the rubber, a looser crosslinking network, and a weakening of intermolecular forces, making it more prone to breakage or oxidative cracking during thermo-oxidative aging. Lignosulfonate has free radical scavenging capabilities, and its absence leads to a decrease in antioxidant properties. In a reducing environment, the rubber has already undergone chemical degradation. Therefore, the lack of modified lignin sulfonate results in a significant decrease in the anti-aging and anti-reduction properties of the rubber.

[0103] Compared with Example 1, the carbon black was converted into white carbon black, and the strength of both examples decreased slightly.

[0104] Compared with Example 1, Comparative Example 4 lacks carbon black, which significantly reduces mechanical strength and resistance to photo-oxidation. Carbon black can absorb ultraviolet light, and its absence leads to the exposure of rubber molecular chains, accelerating photo-oxidation. Therefore, the anti-aging and anti-reduction properties of this comparative example are reduced. The strength of graphite / carbon fiber is also insufficient compared to carbon black.

[0105] Comparative Examples 5 and 6 used other antioxidants, and the test results were not significantly different from those of Example 1.

[0106] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the present invention in any form or substance. It should be noted that any improvements and additions made by those skilled in the art without departing from the method of the present invention should also be considered within the scope of protection of the present invention. Any modifications, alterations, and equivalent changes made by those skilled in the art using the above-disclosed technical content without departing from the spirit and scope of the present invention are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the present invention.

Claims

1. A modified liquid reclaimed adhesive, characterized in that, By weight, the raw materials include: 70-90 phr of waste tire rubber powder, 0.5-8 phr of maleic acid modified resin, and 1-20 phr of modified lignin sulfonate.

2. The modified liquid reclaimed adhesive according to claim 1, characterized in that, By weight, the raw materials include: 80-90 phr of waste tire rubber powder, 5-8 phr of maleic acid modified resin, 10-20 phr of modified lignin sulfonate, and 0.5-15 phr of processing aids.

3. The modified liquid reclaimed adhesive according to claim 1 or 2, characterized in that, The maleic acid modified resin is any one of maleic acid modified terpene resin, maleic acid modified DCPD resin, or maleic acid grafted C5 to C9 resin.

4. A modified liquid reclaimed adhesive according to claim 1 or 2, characterized in that: The processing aid is any one of aromatic oils, naphthenic oils, paraffin oils, and tall oils.

5. A rubber composition for modified liquid reclaimed rubber, characterized in that, According to claims 1-4, a modified liquid reclaimed adhesive comprises, by weight, the following raw materials: 10-50 phr of modified liquid reclaimed adhesive, 50-90 phr of antioxidant, and 5-10 phr of dispersant.

6. The rubber composition of a modified liquid reclaimed rubber according to claim 5, characterized in that, The antioxidant is any one or more of antioxidant RD, antioxidant 6PPD, antioxidant DTPD, antioxidant 4030, antioxidant 4010NA, and antioxidant 1068.

7. The rubber composition of a modified liquid reclaimed rubber according to claim 5, characterized in that: The dispersing agent is any one of carbon black, silica, lignin, and graphite / carbon fiber.

8. A method for preparing a rubber composition of modified liquid reclaimed rubber, characterized in that, The rubber composition of the modified liquid reclaimed rubber according to any one of claims 1-7 comprises the following steps: S1. Add waste tire rubber powder, maleic acid modified resin, and modified lignin sulfonate into a high-speed mixing tank and stir to mix to obtain a mixture. S2. Transfer the mixture into a low-speed mixing tank and stir to obtain premixed rubber powder; S3. Add the premixed rubber powder to the desulfurization extruder of the liquid reclaimed rubber, and obtain the modified liquid reclaimed rubber after desulfurization. S4, Cool modified liquid reclaimed rubber, blended with antioxidant; S5. Extruding the blend with the dispersant yields a rubber composition of a modified liquid reclaimed rubber.

9. A method for preparing a rubber composition of modified liquid reclaimed rubber according to claim 8, characterized in that, The stirring speed in step S1 is 100~2000 rpm, and the stirring time is 5~20 minutes; the stirring speed in step S2 is 20~100 rpm, and the stirring is continuous.

10. A method for preparing a rubber composition of modified liquid reclaimed rubber according to claim 8, characterized in that, In step S3, the desulfurization temperature is 250~400℃; in step S4, the temperature is cooled to 50~80℃.

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