Composite masterbatch-containing cord fabric rubber composition and preparation method thereof

Abstract

The invention relates to the technical field of tire rubber, and discloses a cord fabric rubber composition containing composite masterbatch and a preparation method of the cord fabric 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 tire cord layer rubber composition containing a composite masterbatch and a preparation method thereof. Background Art

[0002] The most important material in a tire is its adhesive compound, such as the belt compound, carcass compound, transition layer compound, and even the adhesive sheet compound. While the adhesive compound formula is generally not easily adjusted during tire design, extensive research has been conducted on its performance, including static mechanical properties before and after aging, bond strength, and dynamic heat generation. The tire's ply rubber, like the skeleton in the human body, is a core component that supports the tire structure and transmits loads. It is composed of a rubber matrix and is composited with tire cord (nylon, polyester, or steel wire). During driving, it withstands internal pressure and tension, impact loads, and dynamic flexure. Its performance directly determines the tire's lifespan and safety. Therefore, the ply rubber must combine high strength, high adhesion, and fatigue resistance.

[0003] Natural rubber (NR) and furnace carbon black (such as N330 and N550) are used extensively in the tire cord ply rubber to enhance adhesion and flexural fatigue performance. Natural rubber, primarily composed of cis-1,4-polyisoprene, has a highly flexible and crystalline molecular chain. When stretched or flexed, the molecular chains absorb energy through conformational changes, slowing crack propagation. This property enables natural rubber to maintain structural integrity under repeated deformation conditions (such as tire rolling), laying the foundation for flexural fatigue performance. Despite its low polarity, the double bonds in its molecular chains can chemically crosslink or physically adsorb with reactive groups on the cord surface (such as amide groups in nylon cord and the oxide layer in steel cord) through vulcanization. Furthermore, the high elasticity of natural rubber creates a "wrapping effect" on the cord surface, similar to an "elastic bandage" that enhances interfacial bonding. Oxygen-containing functional groups (such as hydroxyl and carboxyl groups) on the carbon black surface physically adsorb (via van der Waals forces) or chemically interact (such as with the vulcanization system) with the rubber molecular chains, forming a "bound rubber layer." When the material flexes, microslip at the interface between carbon black aggregates and rubber dissipates energy, reducing local stress peaks and slowing crack propagation. This mechanism acts like a "shock absorber," minimizing fatigue damage. However, both natural rubber and furnace carbon black are derived from disposable resources, resulting in high costs and a large carbon footprint.

[0004] Currently, several improvements are being made to improve the bonding strength and flexural fatigue performance of the rubber ply, but obvious problems still exist. 1) Surface modification of solid reclaimed rubber using a silane coupling agent. The alkoxy groups (-OCH3) of the coupling agent react with the hydroxyl groups (-OH) on the surface of the solid reclaimed rubber to form Si-OC chemical bonds. Simultaneously, its organic functional groups (such as vinyl) react with the double bonds of the matrix rubber (such as natural rubber) through free radical addition. The silane coupling agent forms a "bridge" structure between the reclaimed rubber and the matrix rubber, increasing the interfacial bonding energy while reducing the Mooney viscosity of the rubber and improving processing fluidity. However, there are still residual hard lumps in the solid reclaimed rubber, which leads to local stress concentration and "fisheye" defects. 2) After the cracked carbon black is activated by acid washing, the surface active sites bind to the silane coupling agent, which forms "active anchor points" on the carbon black surface. Its organic chain segments (such as bis-(γ-triethoxysilylpropyl) tetrasulfide) undergo cross-linking reactions with rubber molecular chains, increasing the crosslink density at the carbon black-rubber interface. However, this solution is complex to manufacture and has high costs, making it difficult to promote. 3) A ternary system of resorcinol (R)-formaldehyde (H)-hexamethylenetetramine (HMT) is used, in which HMT acts as a formaldehyde slow-release agent, condensing with resorcinol to form a thermosetting resin, which forms covalent bonds with the hydroxyl groups on the cord surface, thereby improving the cord's adhesion strength. However, this solution carries significant operational toxicological risks, can delay vulcanization, and reduce production efficiency. Therefore, a masterbatch system is urgently needed that can simultaneously reduce costs and emissions while maintaining the adhesion and flexural properties of the cord.

[0005] Liquid reclaimed rubber is a low-viscosity rubber-like liquid obtained by desulfurizing and plasticizing scrap tires and rubber products through physical and chemical methods. 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 the rubbers and weaken the bond strength of the cord.

[0006] Pyrolysis carbon black is a solid carbonaceous residue left after removing volatile matter (such as small molecule hydrocarbons, combustible gas) from carbon-containing raw materials such as waste tires, rubber products and plastics in an oxygen-free or oxygen-deficient environment at high temperature (usually 500-900 DEG C). Its main component is carbon, and it also contains ash, a small amount of volatile matter and residual metal. It is an important product of resource recycling, and has environmental protection and industrial application value. However, the pyrolysis carbon black has higher disorder degree of graphite layer accumulation and forms more micropores, resulting in slightly weaker reinforcing performance but stronger adsorption; the surface polar oxygen-containing groups make the interface bonding force between the pyrolysis carbon black and non-polar rubber (such as NR) weaker. Therefore, how to use the more environmentally friendly recycled resource-pyrolysis carbon black to enhance the adhesion strength and flexing performance of the rubber compound is a problem worth considering. SUMMARY

[0007] The present application provides a cord rubber composition containing a composite masterbatch and a preparation method thereof.

[0008] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0009] A cord rubber composition containing a composite masterbatch, the rubber composition is prepared by mixing the following components by weight based on 100 parts of rubber matrix:

[0010] 70-90 parts by weight of natural rubber,

[0011] 10-30 parts by weight of composite masterbatch,

[0012] 40-60 parts by weight of furnace carbon black,

[0013] 1.0-3.0 parts by weight of vulcanizing agent,

[0014] 1.0-4.0 parts by weight of accelerator,

[0015] 4.0-6.0 parts by weight of activator;

[0016] The rubber matrix is natural rubber and composite masterbatch;

[0017] The composite masterbatch is prepared by mixing the following components by weight based on 100 parts of raw rubber:

[0018] 100 parts by weight of natural rubber,

[0019] 10-25 parts by weight of liquid reclaimed rubber,

[0020] 5-15 parts by weight of pyrolysis carbon black,

[0021] 0.3-1.0 parts by weight of hexamethylene tetramine;

[0022] The liquid recycled rubber has a glass transition temperature Tg of -60 to -50°C and an oil content of 4 to 8 wt%;

[0023] 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%.

[0024] Preferably, the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber:

[0025] 75-85 parts by weight of natural rubber,

[0026] 15 to 25 parts by weight of composite masterbatch,

[0027] 40-60 parts by weight of furnace carbon black,

[0028] 1.0 to 3.0 parts by weight of a vulcanizing agent,

[0029] 1.0 to 4.0 parts by weight of accelerator,

[0030] 4.0 to 6.0 parts by weight of activator,

[0031] 1.0 to 4.0 parts by weight of antioxidant,

[0032] 1.0-4.0 parts by weight of microcrystalline wax

[0033] Preferably, the mass ratio of hexamethylenetetramine to cracked carbon black is (1.4-2.2):100.

[0034] Preferably, the method for preparing the composite masterbatch comprises the following steps:

[0035] 1) Put the natural rubber into an internal mixer and mix it at 100-110°C for 40-60 seconds;

[0036] 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.;

[0037] 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.

[0038] Preferably, the activator comprises zinc oxide and stearic acid, with 2.0 to 4.0 parts by weight of zinc oxide and 1.0 to 2.0 parts by weight of stearic acid.

[0039] Preferably, the vulcanizing agent is insoluble sulfur.

[0040] Preferably, the accelerator is accelerator NS and / or accelerator TMTD.

[0041] Preferably, the antioxidant is a combination of two or three of 4020, RD, DTPD and CPL.

[0042] Furthermore, the present invention also provides a method for preparing the rubber composition for a cord layer containing a composite masterbatch, comprising the following steps:

[0043] 1) Mixing stage: 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 145-155°C and the rubber is discharged to obtain a first stage of rubber;

[0044] 2) Mixing stage 2: Use an internal mixer to mix, add the first-stage rubber, antioxidant, vulcanizing agent, and accelerator, mix until the temperature reaches 100-10°C, discharge the rubber, and cool the sheet to room temperature to obtain a rubber composition.

[0045] Preferably, the rubber composition is vulcanized at a temperature of 150 to 170° C. and for a time of 10 to 20 minutes.

[0046] Furthermore, the present invention also provides the use of the tire cord ply rubber composition containing the composite masterbatch in the preparation of the tire cord ply.

[0047] Furthermore, the present invention also provides a tire, comprising a tread, a belt layer, a cord layer, a sidewall and a bead, wherein the cord layer is prepared by vulcanizing the cord layer rubber composition containing the composite masterbatch.

[0048] The present invention provides a rubber composition for a cord layer 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 adhesion strength of the cord; and there is no free amine odor after HMT premixing, and TVOC is compliant. It also avoids the agglomeration of solid reclaimed rubber lumps and carbon black to form particles within the thin rubber surface. In addition, the composite masterbatch can also maintain the mechanical properties of the cord layer rubber while enhancing the fatigue resistance of the cord layer rubber. The ash of the pyrolysis carbon black contains ZnS, which can replace part of ZnO to release Zn 2+ Activated vulcanization reduces zinc oxide addition and reduces heavy metal emissions. In summary, rubber compositions containing composite masterbatches offer lower costs than those made with natural rubber and furnace carbon black, lower carbon emissions, a wider scorch safety zone, and improved bonding strength and fatigue resistance. DETAILED DESCRIPTION

[0049] 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.

[0050] The examples and comparative examples of the composite masterbatch are shown in Table 1.

[0051] The preparation method of composite masterbatch is as follows:

[0052] 1) Put the natural rubber into an internal mixer and mix at 100℃ for 50s;

[0053] 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.;

[0054] 3) Add liquid recycled rubber and continue mixing for 45 seconds until the peak temperature reaches 150°C and then produce the sheet.

[0055] The preparation method of ordinary masterbatch refers to that of compound masterbatch.

[0056] The difference between Comparative Examples 1-3 and Example 1 lies in the formulation, as shown in Table 1.

[0057] 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.

[0058] Table 1

[0059] 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

[0060] Table 1 footnotes:

[0061] *1: Natural rubber, 3L, Vietnam

[0062] *2: Liquid recycled rubber, 60 mesh, Zhongce Recycling Technology Co., Ltd.

[0063] *3: Pyrolysis carbon black, CB60, Weihailongyinda

[0064] *4: Hexamethylenetetramine (HMT), Shandong Yanggu Huatai

[0065] The application example formula is shown in Table 2.

[0066] Application Examples 1-3 were added with the composite masterbatch prepared in Examples 1-3 in sequence.

[0067] Application Examples 4 and 5 both added the composite masterbatch prepared in Example 1.

[0068] Application Examples 6-8 were added with the common masterbatches of Comparative Examples 1-3 in sequence.

[0069] In Application Example 9, no masterbatch is added, and liquid reclaimed rubber, cracked carbon black, and hexamethylenetetramine are added simultaneously.

[0070] In Application Example 10, no masterbatch was added, 100 parts by weight of natural rubber and 4.0 parts by weight of zinc oxide were added.

[0071] Application example: Mixing is carried out according to the following method. The specific steps are as follows:

[0072] 1) Mixing stage: start the internal mixer, set the rotor speed of the internal mixer to 40 rpm, the mixing pressure to 12 MPa, the cooling water temperature to 35°C, and the rotor temperature to 35°C; add natural rubber, compound masterbatch, carbon black, zinc oxide, stearic acid, and microcrystalline wax, mix for 30 seconds, lift the top plug, hold for 10 seconds, press the top plug, mix until the temperature reaches 130°C, lift the top plug, hold for 10 seconds, press the top plug, and wait until the temperature reaches 150°C before draining to obtain a first stage of rubber;

[0073] 2) Mixing stage 2: Start the internal mixer, set the rotor speed of the internal mixer to 30 rpm, the mixing pressure to 10 MPa, the cooling water temperature to 35°C, and the rotor temperature to 40°C, put the first-stage rubber, insoluble sulfur, accelerator, and antioxidant into the mixing chamber, mix for 50 seconds, lift the top plug, hold for 10 seconds, press the top plug, mix until the temperature reaches 90°C, lift the top plug, hold for 10 seconds, press the top plug, when the rubber temperature reaches 100°C, lift the plug and discharge the rubber, and cool the lower sheet to room temperature to obtain the rubber composition.

[0074] Table 2

[0075]

[0076]

[0077] Table 2 footnotes:

[0078] *1: Natural rubber, 3L, Vietnam

[0079] *2: Furnace black, Cabot N326

[0080] *3: Liquid recycled rubber, 60 mesh, Zhongce Recycling Technology Co., Ltd.

[0081] *4: Pyrolysis carbon black CB60, Weihai Longyinda

[0082] *5: Hexamethylenetetramine (HMT), Shandong Yanggu Huatai

[0083] *6: Insoluble sulfur OT20, Shandong Shangshun

[0084] All reagents are commercially available.

[0085] The rubber cord layer obtained in the application example was used for various performance tests, and the test results are shown in Table 2.

[0086] The test items are as follows:

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

[0088] 2) Elongation at break: Refer to ISO 37, tensile speed 500 mm min -1 .

[0089] 3) Tensile stress M100: Refer to ISO 37, tensile speed 500mm min -1 .

[0090] 4) T-peel test: refer to ASTM D1876, 100mm min -1 The tensile load is applied at a constant speed.

[0091] 5) Flexural properties: Determine the flexural temperature rise according to ISO 132-2 (DeMattia method), 100°C, 100h.

[0092] 6) Scorch time Ts10: Refer to ISO 6502.

[0093] From Table 2, we can see that Application Examples 1-5 have better elongation at break, bonding strength and flexural properties, and their tensile strength and modulus of elongation M100 are also not low.

[0094] TB (Tensile Strength): The tensile strength of Application Examples 1-5 (adding a composite masterbatch) is slightly lower than that of Application Example 10 (a pure natural rubber system), but significantly higher than that of Application Examples 6-9 (using conventional or no masterbatch systems). 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.

[0095] 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.

[0096] M100 (modulus) : The modulus of application examples 1-5 (adding the composite masterbatch) is close to that of application example 10 (pure natural rubber system), but is obviously higher than that of application examples 6-9 (ordinary masterbatch or no masterbatch system). It can be seen that the effect of the composite masterbatch on the modulus of the rubber composition is negligible, and the pyrolytic carbon black and hexamethylenetetramine must be premixed.

[0097] T-peel (adhesion strength) : The adhesion strength of application examples 1-5 (adding the composite masterbatch) reaches 11-12.5 N·mm -1 , which 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 force between the cord and the rubber, and the improvement in strength is better than that of the material directly added, and the masterbatch obtained by premixing and mixing the pyrolytic carbon black and hexamethylenetetramine has a better effect on improving the adhesion strength of the rubber.

[0098] Flex fatigue temperature rise : The flex fatigue temperature rise of application examples 1-5 (adding the composite 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.

[0099] Scorch time (Ts10) : The scorch safety zone of application examples 1-5 (adding the composite masterbatch) is larger, indicating that the composite masterbatch system improves the processing safety.

[0100] The above describes the embodiments of the present application, and through the above description of the disclosed embodiments, those skilled in the art can implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tire cord ply 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 the rubber matrix: 70-90 parts by weight of natural rubber, 10 to 30 parts by weight of composite masterbatch, 40-60 parts by weight of furnace carbon black, 1.0 to 3.0 parts by weight of a vulcanizing agent, 1.0 to 4.0 parts by weight of accelerator, 4.0-6.0 parts by weight of activator; The rubber matrix is ​​natural rubber and composite masterbatch; 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 tire cord ply rubber composition containing a composite masterbatch according to claim 1, wherein: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 75-85 parts by weight of natural rubber, 15 to 25 parts by weight of composite masterbatch, 40-60 parts by weight of furnace carbon black, 1.0 to 3.0 parts by weight of a vulcanizing agent, 1.0 to 4.0 parts by weight of accelerator, 4.0 to 6.0 parts by weight of activator, 1.0 to 4.0 parts by weight of antioxidant, 1.0-4.0 parts by weight of microcrystalline wax 3. A carcass 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 carcass rubber composition containing a composite masterbatch according to claim 1 or 2, 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 carcass rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The activator comprises zinc oxide and stearic acid, wherein the zinc oxide is 2.0 to 4.0 parts by weight and the stearic acid is 1.0 to 2.0 parts by weight.

6. A carcass rubber composition containing a composite masterbatch according to claim 1 or 2, characterized in that: The vulcanizing agent is insoluble sulfur; And / or, the accelerator is accelerator NS and / or accelerator TMTD; And / or, the antioxidant is a combination of two or three of 4020, RD, DTPD, and CPL.

7. The method for preparing a tire cord ply rubber composition containing a composite masterbatch according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) Mixing stage: Use internal mixer to mix, add raw rubber, filler, chemical additives and mix. Chemical additives here do not include antioxidant, vulcanizing agent and accelerator. Mix until the temperature reaches 145-155℃ and the rubber is discharged to obtain a first stage rubber; 2) Mixing stage 2: Use an internal mixer to mix, add the first-stage rubber, antioxidant, vulcanizing agent, and accelerator, mix until the temperature reaches 100-10°C, discharge the rubber, and cool the sheet to room temperature to obtain a rubber composition.

8. The method for preparing a carcass rubber composition containing a composite masterbatch according to claim 7, characterized in that: The vulcanization temperature of the rubber composition is 150-170° C., and the vulcanization time is 10-20 minutes.

9. Use of the tire cord ply rubber composition containing the composite masterbatch according to any one of claims 1 to 6 in the preparation of tire cord plies.

10. A tire comprising a tread, a belt layer, a cord layer, a sidewall and a bead, characterized in that: The cord layer is prepared by vulcanizing a cord layer rubber composition containing a composite masterbatch as claimed in any one of claims 1 to 6.

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