Transition layer rubber composition containing composite masterbatch and preparation method thereof

Abstract

The invention relates to the technical field of tire rubber, and discloses a transition layer rubber composition containing composite masterbatch and a preparation method of the transition layer rubber composition. Composite masterbatch is introduced into the rubber composition, and the rubber composition is prepared by mixing natural rubber, liquid regenerated rubber, cracked carbon black and hexamethylenetetramine. Wherein the glass transition temperature Tg of the liquid regenerated rubber is-60 to-50 DEG C, and the oil content of the liquid regenerated rubber is 4-8wt%; the BET specific surface area of the cracked carbon black is 60-100 m < 2 >. G <-1 >, the ash content is 15-25 wt%, and the ZnS content in the ash content is 5-12 wt%. The added composite master batch can effectively replace part of natural rubber and furnace black, the bonding strength and fatigue resistance of the rubber material are improved and the scorching safety area is expanded on the premise of not influencing the mechanical properties of the rubber composition, and the composite master batch is beneficial to reduction of heavy metal emission and carbon emission and improvement of economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of tire rubber, in particular to a transition layer rubber composition containing a composite masterbatch and a preparation method thereof. Background Art

[0002] In the complex construction of a tire, the transition layer is a layer of rubber between the carcass and the innerliner. Its function is to improve the adhesion between the innerliner and the carcass ply to prevent delamination during tire use. This requires the transition layer rubber to have high viscosity and good adhesion to the steel wire.

[0003] However, the current development and application of transition layer compounds also face numerous challenges. On the one hand, the trend toward higher-performance and greener tires places higher demands on transition layer compounds in terms of reduced rolling resistance, reduced heat generation, and improved environmental performance. Traditional compound formulations struggle to meet these demands. On the other hand, some raw materials, such as natural rubber and carbon black, rely on disposable resources, resulting in high costs and significant carbon emissions during production, which is inconsistent with the concept of sustainable development. Furthermore, while some new materials and technologies can theoretically improve the performance of transition layer compounds, in practice they face challenges such as complex processes, high production costs, and insufficient stability, limiting their widespread adoption.

[0004] Liquid reclaimed rubber is a low-viscosity rubber-like liquid obtained by physically and chemically crushing waste tires and rubber products, followed by desulfurization and plasticization. Its main components are: 1) Rubber matrix: degradation products of waste rubber such as natural rubber (NR) and styrene-butadiene rubber (SBR); 2) Functional additives: softeners (such as vegetable oil-based plasticizers), activators (dithiocarbamates), antioxidants, etc. Liquid reclaimed rubber is more adaptable to processing than traditional reclaimed rubber—it can be directly injected into the mixer, resulting in higher dispersion efficiency and better environmental protection. The short-chain rubber molecules in the reclaimed rubber act as "molecular plasticizers," filling the natural rubber network and reducing stress concentration. However, directly adding liquid reclaimed rubber will dilute the crosslink density between rubbers and weaken the adhesive strength of the rubber compound.

[0005] Pyrolysis carbon black is a solid carbonaceous residue remaining after pyrolysis of carbon-containing raw materials such as scrap tires, rubber products, and plastics at high temperatures (typically 500-900°C) in an oxygen-free or anoxic environment to remove volatile components (such as small hydrocarbons and combustible gases). Its primary component is carbon, with ash, small amounts of volatiles, and residual metals. It is an important product for resource recycling, offering both environmental and industrial applications. However, the graphite layers of pyrolysis carbon black are more disordered, forming more micropores, resulting in slightly weaker reinforcing properties but stronger adsorption. Its surface polar oxygen groups weaken its interfacial bonding with non-polar rubbers (such as NR). Therefore, how to utilize pyrolysis carbon black, a more environmentally friendly recycled resource, to enhance the adhesive strength and flexural properties of rubber compounds is a question worth considering. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a transition layer rubber composition containing a composite masterbatch and a preparation method thereof.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0008] A transition layer rubber composition containing a composite masterbatch, wherein the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber:

[0009] 40-60 parts by weight of natural rubber,

[0010] 40-60 parts by weight of styrene-butadiene rubber,

[0011] 20-30 parts by weight of composite masterbatch,

[0012] 50-70 parts by weight of furnace carbon black;

[0013] The composite masterbatch is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber:

[0014] 100 parts by weight of natural rubber,

[0015] 10 to 25 parts by weight of liquid regenerated rubber,

[0016] 5 to 15 parts by weight of pyrolysis carbon black,

[0017] 0.3-1.0 parts by weight of hexamethylenetetramine;

[0018] The liquid recycled rubber has a glass transition temperature Tg of -60 to -50°C and an oil content of 4 to 8 wt%;

[0019] The BET specific surface area of ​​the pyrolysis carbon black is 60 to 100 m 2 ·g -1, ash content is 15-25wt%, and ZnS content in the ash is 5-12wt%.

[0020] Preferably, the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber:

[0021] 45-55 parts by weight of natural rubber,

[0022] 45-55 parts by weight of styrene-butadiene rubber,

[0023] 23-27 parts by weight of composite masterbatch,

[0024] 55-65 parts by weight of furnace carbon black;

[0025] 1.0 to 4.0 parts by weight of zinc oxide,

[0026] 1.0 to 4.0 parts by weight of antioxidant,

[0027] 1.0 to 6.0 parts by weight of a vulcanizing agent,

[0028] 1.0 to 4.0 parts by weight of accelerator.

[0029] Preferably, the mass ratio of hexamethylenetetramine to cracked carbon black is (1.4-2.2):100.

[0030] Preferably, the method for preparing the composite masterbatch comprises the following steps:

[0031] 1) Put the natural rubber into an internal mixer and mix it at 100-110°C for 40-60 seconds;

[0032] 2) adding the pyrolysis carbon black-hexamethylenetetramine premix to step 1) and mixing for 20 to 40 seconds to raise the material temperature to 120 to 130° C.;

[0033] 3) Add liquid recycled rubber and continue mixing for 40 to 60 seconds until the peak temperature reaches 145 to 155°C and the sheet is produced.

[0034] Preferably, the vulcanizing agent is insoluble sulfur.

[0035] Preferably, the accelerator is accelerator CZ.

[0036] Preferably, the antioxidant is antioxidant 4020.

[0037] Furthermore, the present invention also provides a method for preparing the transition layer rubber composition containing the composite masterbatch, comprising the following steps:

[0038] 1) One-stage mixing: using an internal mixer to mix, adding raw rubber, fillers, and chemical additives for mixing, where the chemical additives do not include antioxidants, vulcanizing agents, and accelerators, mixing until the temperature reaches 145-165°C and the rubber is discharged to obtain a first-stage rubber;

[0039] 2) Second stage mixing: using an internal mixer for mixing, adding the first stage rubber, antioxidant, vulcanizing agent and accelerator for mixing, and cooling the sheet to room temperature to obtain a rubber composition.

[0040] Preferably, the rubber composition is vulcanized at a temperature of 150 to 170° C. and for a time of 10 to 20 minutes.

[0041] Preferably, the present invention further provides a tire, comprising a transition layer, wherein the transition layer is prepared by vulcanizing the transition layer rubber composition containing the composite masterbatch.

[0042] The present invention provides a transition layer rubber composition containing a composite masterbatch and a preparation method thereof. The ZnS / SiO2 acid center in the ash of the pyrolysis carbon black in the composite masterbatch can lock the HMT complex, continuously provide active formaldehyde-amine free radicals when vulcanized at 150°C, and form a trace amount of R / H-type bridges "on site", thereby improving the bonding strength of the cord fabric; and there is no free amine odor after HMT premixing, and TVOC is compliant. It also avoids the solid reclaimed rubber lumps and carbon black agglomeration to form particles in the thin rubber surface. In addition, the composite masterbatch can also maintain the mechanical properties of the belt layer rubber while enhancing the fatigue resistance of the belt layer rubber. The ash of the pyrolysis carbon black contains ZnS, which can replace part of ZnO to release Zn 2+ Activated vulcanization reduces heavy metal emissions. In summary, rubber compositions containing composite masterbatches have lower costs than rubber compositions containing natural rubber and furnace carbon black, lower carbon emissions, a larger scorch safety zone, and better bonding strength and fatigue resistance. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0044] The examples and comparative examples of the composite masterbatch are shown in Table 1.

[0045] The preparation method of composite masterbatch is as follows:

[0046] 1) Put the natural rubber into an internal mixer and mix at 100℃ for 50s;

[0047] 2) premixing the pyrolysis carbon black and hexamethylenetetramine uniformly, then adding the pyrolysis carbon black-hexamethylenetetramine premix to step 1), and mixing for another 30 seconds to raise the material temperature to 125° C.;

[0048] 3) Add liquid recycled rubber and continue mixing for 45 seconds until the peak temperature reaches 150°C and then produce the sheet.

[0049] The preparation method of ordinary masterbatch refers to that of compound masterbatch.

[0050] The difference between Comparative Examples 1-3 and Example 1 lies in the formulation, as shown in Table 1.

[0051] The difference between Comparative Example 4 and Example 1 lies in the preparation method. In step 2), the pyrolysis carbon black and hexamethylenetetramine are not pre-mixed but are directly and simultaneously put into an internal mixer for mixing.

[0052] Table 1

[0053] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Natural rubber*1 100 100 100 100 100 100 Liquid recycled rubber*2 24 12 18 0 0 24 Pyrolysis carbon black*3 15 8 12 15 15 15 Hexamethylenetetramine*4 0.3 0.4 0.8 0 0.3 0.3

[0054] Table 1 footnotes:

[0055] *1: Natural rubber, 3L, Vietnam

[0056] *2: Liquid recycled rubber, 60 mesh, Zhongce Recycling Technology Co., Ltd.

[0057] *3: Pyrolysis carbon black, CB60, Weihailongyinda

[0058] *4: Hexamethylenetetramine (HMT), Shandong Yanggu Huatai

[0059] The application example formula is shown in Table 2.

[0060] Application Examples 1-3 were added with the composite masterbatch prepared in Examples 1-3 in sequence.

[0061] Application Examples 4 and 5 both added the composite masterbatch prepared in Example 1.

[0062] Application Examples 6-8 were added with the common masterbatches of Comparative Examples 1-3 in sequence.

[0063] In Application Example 9, no masterbatch is added, and liquid reclaimed rubber, cracked carbon black, and hexamethylenetetramine are added simultaneously.

[0064] In Application Example 10, no masterbatch was added, and 100 parts by weight of natural rubber was added.

[0065] Application example: Mixing is carried out according to the following method. The specific steps are as follows:

[0066] 1) One-stage mixing: Use an internal mixer to mix, add raw rubber, fillers, and chemical additives for mixing. The chemical additives here do not include antioxidants, vulcanizers, and accelerators. Pressurize to a temperature of 120-130°C, remove the roller for cleaning, and then pressurize to a temperature of 150-165°C for rubber discharge to obtain a first-stage rubber;

[0067] 2) Second stage mixing: Use internal mixer for mixing, add first stage rubber, antioxidant, vulcanizing agent and accelerator for mixing, pressurize and mix for 20-35 seconds, lift the mixer for cleaning, pressurize to 100-110℃ for rubber discharge, and cool to room temperature to obtain the rubber composition.

[0068] Table 2

[0069]

[0070]

[0071] Table 2 footnotes:

[0072] *1: Natural rubber, 3L, Vietnam

[0073] *2: Styrene-butadiene rubber SBR1712, Sinopec

[0074] *3: Furnace black, Cabot N550

[0075] *4: Liquid recycled rubber, 60 mesh, Zhongce Recycling Technology Co., Ltd.

[0076] *5: Pyrolysis carbon black CB60, Weihai Longyinda

[0077] *6: Hexamethylenetetramine (HMT), Shandong Yanggu Huatai

[0078] *7: Zinc oxide, Shijiazhuang Zhiyi

[0079] *8: Antioxidant 4020, Shandong Shengao

[0080] *9: Insoluble sulfur OT20, Shandong Shangshun

[0081] *10: Accelerator DZ, Shandong Shangshun

[0082] All reagents are commercially available.

[0083] The belt rubber obtained in the application example was used for various performance tests, and the test results are shown in Table 2.

[0084] The test items are as follows:

[0085] 1) Tensile strength: Refer to ISO 37, tensile speed 500mm min -1 .

[0086] 2) Elongation at break: Refer to ISO 37, tensile speed 500 mm min -1 .

[0087] 3) Tensile stress M100: Refer to ISO 37, tensile speed 500mm min -1 .

[0088] 4) T-peel test: refer to ASTM D1876, 100mm min -1 The tensile load is applied at a constant speed.

[0089] 5) Flexural properties: Determine the flexural temperature rise according to ISO 132-2 (DeMattia method), 100°C, 100h.

[0090] 6) Scorch time Ts10: Refer to ISO 6502.

[0091] From Table 2, it can be seen that Application Examples 1-5 have better elongation at break, bonding strength and flexural properties, and their tensile strength and modulus of tensile stress M100 are close to those of Application Example 10.

[0092] TB (Tensile Strength): The tensile strengths of Application Examples 1-5 (with the addition of a composite masterbatch) were slightly higher than those of Application Example 10 (pure natural rubber system) and Application Examples 6-9 (with conventional or no masterbatch system). This indicates that the effect of the composite masterbatch on the tensile strength of the rubber composition is negligible, and that the pyrolysis carbon black and hexamethylenetetramine must be premixed.

[0093] EB (elongation at break): The elongation at break of application examples 1-5 (adding compound masterbatch) is better than that of other application examples, indicating that the compound masterbatch can effectively enhance the elasticity of the rubber composition, and the cracked carbon black and hexamethylenetetramine must be mixed in advance, otherwise the effectiveness of the compound masterbatch will be affected.

[0094] M100 (tensile stress at modulus): This stress at modulus reflects the rubber compound's resistance to deformation. The tensile stresses of Examples 1-5 (with the addition of a composite masterbatch) are close to those of Example 10 (a pure natural rubber system) and higher than those of Examples 6-9 (with conventional or no masterbatch systems). This indicates that the composite masterbatch has a negligible effect on the tensile stress of the rubber composition, and that the pyrolysis carbon black and hexamethylenetetramine must be premixed.

[0095] T-peel (bonding strength): The bonding strength of application examples 1-5 (adding composite masterbatch) is significantly higher than that of application examples 6-9 (ordinary masterbatch or no masterbatch system) and application example 10 (pure natural rubber system), indicating that the composite masterbatch effectively improves the interfacial bonding strength between the cord and the rubber, and the enhanced strength is better than that of directly adding the materials separately, and the masterbatch obtained by premixing and kneading cracked carbon black and hexamethylenetetramine is more effective in improving the bonding strength of the rubber compound.

[0096] Flexural temperature rise: The flexural temperature rise of application examples 1-5 (adding compound masterbatch) is lower than that of application examples 6-9 (ordinary masterbatch or no masterbatch system) and application example 10 (pure natural rubber system), indicating that it has better fatigue resistance and more balanced stress distribution.

[0097] Scorch time (Ts10): The scorch safety zone of application example 1-5 (adding compound masterbatch) is larger, indicating that the compound masterbatch system improves processing safety.

[0098] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can 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 should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transition layer rubber composition containing a composite masterbatch, characterized in that: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 40-60 parts by weight of natural rubber, 40-60 parts by weight of styrene-butadiene rubber, 20-30 parts by weight of composite masterbatch, 50-70 parts by weight of furnace carbon black; The composite masterbatch is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 100 parts by weight of natural rubber, 10 to 25 parts by weight of liquid regenerated rubber, 5 to 15 parts by weight of pyrolysis carbon black, 0.3-1.0 parts by weight of hexamethylenetetramine; The liquid recycled rubber has a glass transition temperature Tg of -60 to -50°C and an oil content of 4 to 8 wt%; The BET specific surface area of ​​the pyrolysis carbon black is 60 to 100 m 2 .g -1 , ash content is 15~25wt%, and ZnS content in the ash is 5~12wt%.

2. The transition layer rubber composition containing a composite masterbatch according to claim 1, characterized in that: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 45-55 parts by weight of natural rubber, 45-55 parts by weight of styrene-butadiene rubber, 23-27 parts by weight of composite masterbatch, 55-65 parts by weight of furnace carbon black; 1.0 to 4.0 parts by weight of zinc oxide, 1.0 to 4.0 parts by weight of antioxidant, 1.0 to 6.0 parts by weight of a vulcanizing agent, 1.0 to 4.0 parts by weight of accelerator.

3. A transition layer rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The mass ratio of the hexamethylenetetramine to the cracked carbon black is (1.4-2.2):

100.

4. A transition layer rubber composition containing a composite masterbatch according to any one of claims 1 to 3, characterized in that: The preparation method of the composite masterbatch comprises the following steps: 1) Put the natural rubber into an internal mixer and mix it at 100-110°C for 40-60 seconds; 2) adding the pyrolysis carbon black-hexamethylenetetramine premix to step 1) and mixing for 20-40 seconds to raise the material temperature to 120-130° C.; 3) Add liquid recycled rubber and continue mixing for 40 to 60 seconds until the peak temperature reaches 145 to 155°C and the sheet is produced.

5. A transition layer rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The vulcanizing agent is insoluble sulfur.

6. A transition layer rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The accelerator is accelerator CZ.

7. A transition layer rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The antioxidant is antioxidant 4020.

8. The method for preparing a transition layer rubber composition containing a composite masterbatch according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) One-stage mixing: Use an internal mixer to mix, add raw rubber, fillers, and chemical additives for mixing. The chemical additives here do not include antioxidants, vulcanizers, and accelerators. Mix until the temperature reaches 145-165°C and discharge the rubber to obtain a one-stage rubber; 2) Second stage mixing: Use internal mixer to mix, add first stage rubber, antioxidant, vulcanizing agent and accelerator for mixing, and cool the sheet to room temperature to obtain rubber composition.

9. The method for preparing a transition layer rubber composition containing a composite masterbatch according to claim 8, characterized in that: The vulcanization temperature of the rubber composition is 150-170° C., and the vulcanization time is 10-20 minutes.

10. A tire comprising a transition layer, characterized in that: The transition layer is prepared by vulcanizing a transition layer rubber composition containing a composite masterbatch as claimed in any one of claims 1 to 7.

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