Masterbatch as well as preparation method and application thereof

Abstract

The invention discloses a rubber master batch and a preparation method and application thereof. The method comprises the following steps: adding multiphase filler carbon black slurry, white carbon black slurry and clay slurry into raw rubber, stirring, flocculating, and drying to obtain the rubber master batch. The wet mixing process for preparing the high-performance tire rubber material is realized through a multiphase gradient dispersion technology, and is particularly suitable for manufacturing tread rubber and sidewall rubber of OTR (Off-highway) giant radial tires.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber materials, and particularly relates to a masterbatch and a preparation method and application thereof. Background Art

[0002] In recent years, with the development of the automotive industry towards high speed, safety, energy conservation, comfort, etc., the requirements for the performance of tires have been further improved, which requires tires to have excellent wear resistance, low rolling resistance, good wet skid resistance, and good cut and fatigue resistance, etc.

[0003] Rubber is the main raw material of tires. The traditional modification method of rubber is to adjust the formula of tread rubber composites, such as developing and applying new rubber raw materials and new fillers, etc. The preparation process of rubber mainly includes dry mixing and wet mixing. Among them, dry mixing is to mix solid substances such as rubber raw materials, fillers and other additives in a certain proportion in a mixer or an open mill. However, the traditional dry mixing process has disadvantages such as uneven filler dispersion (carbon black aggregate size > 500nm), mixing temperature > 150°C resulting in rubber molecular chain breakage (Mooney viscosity drop ≥ 15%), and high dynamic heat generation.

[0004] Currently, it is inclined to prepare rubber products through a wet mixing process, that is, to obtain the final product by coagulating and co-precipitating fillers and other additives with latex under liquid phase conditions. However, the wet process also has problems such as easy phase separation during multi-phase filler blending, high dehydration energy consumption, and weak interfacial bonding (filler-rubber binding energy < 50kJ / mol), and it is difficult to meet the harsh requirements of engineering radial tires for masterbatch.

[0005] Therefore, the existing preparation methods of rubber for tires need to be improved. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, the present invention proposes a masterbatch and a preparation method and application thereof.

[0007] In one aspect of the present invention, a method for preparing a masterbatch is proposed. According to an embodiment of the present invention, the method includes: mixing a carbon black slurry, a silica slurry, a clay slurry and a rubber latex, then flocculating, and then drying to obtain the masterbatch, wherein the zeta potentials of the silica slurry, the clay slurry and the carbon black slurry gradually decrease, and the zeta potential difference between two slurries is 10 - 60mV, preferably 20 - 50mV, such as 15mV, 20mV, 25mV, 30mV, 35mV, 40mV, 45mV, 50mV, 55mV, etc.

[0008] In some embodiments, the potential value of the carbon black slurry is -30 mV to -40 mV, such as -31 mV, -32 mV, -33 mV, -34 mV, -35 mV, -36 mV, -37 mV, -38 mV, -39 mV, etc., the potential value of the silica slurry is +5 mV to +10 mV, such as +6 mV, +7 mV, +8 mV, +9 mV, etc., and the potential value of the clay slurry is -10 mV to -20 mV, such as -11 mV, -12 mV, -13 mV, -14 mV, -15 mV, -16 mV, -17 mV, -18 mV, -19 mV, etc. Among them, the carbon black slurry is dominated by negative charges, which can reduce the agglomeration of carbon black. The clay system has medium negative charges, which can promote the interlayer exfoliation of clay. At the same time, the silica slurry has weak positive charges, which can inhibit the sedimentation of silica. Thus, by controlling the formation of potential gradient differences of each slurry, the synergistic dispersion control of heterogeneous fillers such as carbon black, silica, and clay is effectively achieved, greatly improving the dispersion uniformity of the fillers in the rubber.

[0009] In some embodiments, the carbon black, coupling agent, and water are first stirred for the carbon black, the pH is adjusted with ammonia water, and then the first ultrasonic treatment is performed to obtain a carbon black slurry.

[0010] In some embodiments, the carbon black includes at least one of N234 carbon black, N110 carbon black, N330 carbon black, and N220 carbon black.

[0011] In some embodiments, the coupling agent includes at least one of Si75, Si69, and KH550.

[0012] In some embodiments, the mass ratio of the carbon black to the coupling agent is 1:(0.01 - 0.02).

[0013] In some embodiments, the temperature of the first stirring is 50 - 60 °C, and the time is 25 - 30 min.

[0014] In some embodiments, the rotation speed of the first stirring is 500 - 1200 rpm.

[0015] In some embodiments, the solid content of the carbon black slurry is 2 - 8 wt%.

[0016] In some embodiments, the frequency of the first ultrasonic treatment is 35 - 45 Hz, and the time is 5 - 15 min.

[0017] In some embodiments, the pH of the carbon black slurry is 9 - 10.

[0018] In some embodiments, the method for preparing the silica slurry comprises: secondarily stirring silica, an ionic liquid, and water, and then subjecting the mixture to second ultrasonic treatment to obtain the silica slurry.

[0019] In some embodiments, the ionic liquid comprises at least one of (1-butyl-3-methylimidazolium) chloride (i.e., (BMIM)Cl) and 1-butyl-3-methylimidazolium tetrafluoroborate (i.e., [BMIM][BF4]).

[0020] In some embodiments, the mass ratio of the silica to the ionic liquid in the mixture is 1:(0.005 - 0.01).

[0021] In some embodiments, the rotation speed of the second stirring is 500 - 1200 rpm, and the time is 25 - 30 min.

[0022] In some embodiments, the frequency of the second ultrasonic treatment is 35 - 45 Hz, and the time is 15 - 20 min.

[0023] In some embodiments, the solid content of the silica slurry is 2 - 8 wt%.

[0024] In some embodiments, the method for preparing the clay slurry comprises: tertially stirring clay, a surfactant, and water, and then subjecting the mixture to third ultrasonic treatment to obtain the clay slurry.

[0025] In some embodiments, the clay comprises at least one of montmorillonite and kaolin.

[0026] In some embodiments, the surfactant comprises at least one of sodium dodecylbenzenesulfonate and KH570.

[0027] In some embodiments, the mass ratio of the clay to the surfactant in the mixture is 1:(0.15 - 0.25).

[0028] In some embodiments, the rotation speed of the tertial stirring is 500 - 1200 rpm, and the time is 10 - 20 min.

[0029] In some embodiments, the frequency of the third ultrasonic treatment is 35 - 45 Hz, and the time is 5 - 15 min.

[0030] In some embodiments, the solid content of the clay slurry is 2 - 8 wt%.

[0031] In some embodiments, when adding the carbon black slurry, the silica slurry, and the clay slurry into the rubber latex respectively, an interfacial compatibilizer is added between two of the slurries.

[0032] In some embodiments, the interfacial compatibilizer is KH550 and KH570 with a mass ratio of 1:(0.5 - 1).

[0033] In some embodiments, the addition amount of the interfacial compatibilizer is 1 - 5 wt% of the total mass of the carbon black slurry, silica slurry and clay slurry, such as 2 wt%, 3 wt%, 4 wt%, etc.

[0034] In some embodiments, the mass ratio of the rubber latex, carbon black slurry, silica slurry and clay slurry is 100:(30 - 40):(15 - 25):(1 - 35).

[0035] In some embodiments, the rubber includes at least one of natural rubber and styrene - butadiene rubber.

[0036] In some embodiments, the rotation speed of the mixing is 500 - 1200 rpm and the time is 30 - 35 min.

[0037] In some embodiments, the drying is three - stage dehydration, and the three - stage dehydration includes:

[0038] (a) Drying at 78 - 82 °C for 8 - 10 min under a vacuum degree of - 0.08 MPa;

[0039] (b) Drying at 58 - 62 °C for 12 - 15 min under a vacuum degree of - 0.095 MPa;

[0040] (c) Drying at 38 - 42 °C for 18 - 20 min under a vacuum degree of - 0.1 MPa.

[0041] In the second aspect of the present invention, the present invention provides a masterbatch. According to the embodiments of the present invention, the masterbatch is prepared by the method described in the first aspect of the present invention.

[0042] In the third aspect of the present invention, the present invention provides a vulcanizate. According to the embodiments of the present invention, the vulcanizate includes the masterbatch described in the second aspect of the present invention.

[0043] In some embodiments, the tensile strength of the vulcanizate is 28 - 35 MPa, such as 29 MPa, 30 MPa, 31 MPa, 32 MPa, 33 MPa, 34 MPa, etc.

[0044] In some embodiments, the tear strength of the vulcanizate is 100 - 120 kN / m. For example, 102 kN / m, 104 kN / m, 106 kN / m, 108 kN / m, 110 kN / m, 112 kN / m, 114 kN / m, 116 kN / m, 118 kN / m, etc.

[0045] In some embodiments, the DIN abrasion of the vulcanizate is 80-104 mm 3 . For example, 84 mm 3 , 86 mm 3 , 88 mm 3 , 90 mm 3 , 92 mm 3 , 94 mm 3 , 96 mm 3 , 98 mm 3 , 100 mm 3 , 102 mm 3 etc.

[0046] In some embodiments, the heat build-up of the vulcanizate under compression is 18-24 °C. For example, 19 °C, 20 °C, 21 °C, 22 °C, 23 °C, etc.

[0047] In some embodiments, the RPA tanδ (60 °C) of the vulcanizate is 0.090-0.125. For example, 0.095, 0.100, 0.105, 0.110, 0.105, 0.110, 0.115, 0.120, etc.

[0048] In some embodiments, the Shore A hardness of the vulcanizate is 65-67. For example, 66, etc.

[0049] In the fourth aspect of the present invention, the present invention provides an application of the vulcanizate as described in the third aspect of the present invention in a tire tread rubber or a tire sidewall rubber.

[0050] The present invention has the following beneficial effects:

[0051] (1) Improves the uniformity of filler dispersion: In the existing dry mixing process, the filler dispersion is uneven, and the size of carbon black aggregates > 500 nm. However, the multi-phase gradient dispersion method of the present invention effectively realizes the coordinated dispersion control of multiple types of fillers by separately preparing three different modified slurries and using a potential regulation module to form a potential gradient difference among the slurries, greatly improving the uniformity of filler dispersion in the rubber;

[0052] (2) Reduces the damage to rubber properties during mixing: In the dry mixing process, a mixing temperature > 150 °C will cause the rubber molecular chains to break and the Mooney viscosity to decrease by ≥ 15%. However, the three-stage vacuum dehydration system of the present invention adopts a gradient cooling method, with the primary dehydration temperature being 80 ± 2 °C and gradually decreasing to 40 ± 2 °C at the third stage, avoiding the destruction of rubber molecular chains by high temperature and better retaining the original properties of the rubber;

[0053] (3) Enhanced interfacial adhesion: In the traditional wet process, there are problems of phase separation and weak interfacial adhesion during the blending of multi-phase fillers. In the present invention, by adding an interfacial compatibilizer during the rubber latex blending stage, the interfacial adhesion between the filler and the rubber is enhanced, and the filler-rubber binding energy is effectively improved.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be learned through the practice of the present invention. Detailed implementation manners

[0055] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0056] In the following embodiments and comparative examples, unless otherwise specified, the raw materials used are ordinary commercially available products that can be directly purchased in the art or prepared according to the existing conventional methods in the art. The "parts" mentioned in the embodiments and comparative examples all refer to parts by mass.

[0057] Example 1

[0058] (1) Prepare three slurries:

[0059] Carbon black slurry: Mix 35 parts of N234 carbon black, 0.5 part of silane coupling agent Si75 with water, then add ammonia water solution to adjust the pH of the system to 9.5, stir with a high-speed mixer at 800 rpm under the constant temperature condition of 50 °C for 30 minutes, and then perform ultrasonic treatment at 40 kHz for 10 min to form a carbon black slurry with a solid content of 4 wt%;

[0060] Clay slurry: Mix 5 parts of organic montmorillonite, 0.1 part of sodium dodecylbenzenesulfonate with water, treat it in a high-speed shear emulsifier at 800 rpm for 20 minutes, and then perform ultrasonic treatment at 40 kHz for 5 min to form a clay slurry with a solid content of 4 wt%;

[0061] Silica slurry: Mix 20 parts of silica and 0.16 part of (BMIM)Cl with water, treat it in a high-speed mixer at 800 rpm for 20 minutes, and then perform ultrasonic treatment at 40 kHz for 15 minutes to form a silica slurry with a solid content of 4 wt%;

[0062] During the preparation of the three slurries, an online Zeta potentiometer (accuracy ±0.1 mV) is used to monitor the potential values of the three slurries in real time, and the potential values of the carbon black slurry, clay slurry and silica slurry are controlled to be -35 mV, -15 mV and +5 mV respectively by fine-tuning with ammonia water / hydrochloric acid.

[0063] (2) Add the clay slurry, silica slurry, and carbon black slurry into a high-speed mixer containing 70 parts of natural rubber latex (parts are based on dry rubber) and 30 parts of styrene-butadiene rubber latex (parts are based on dry rubber) in sequence for mixing. The feeding interval for each slurry is 5 min. An interfacial compatibilizer is added between different filler slurries. The interfacial compatibilizer is KH550 and KH570 with a mass ratio of 1:1. Among them, the addition amount of the interfacial compatibilizer each time is 1 wt% of the total mass of the three slurries, and it is added in two times. The rotation speed of the high-speed mixer is 100 rpm, and the stirring time is 35 min;

[0064] (3) After the slurries are mixed with the natural rubber latex and styrene-butadiene rubber latex by high-speed stirring, flocculation occurs, and the co-precipitated multiphase filler masterbatch is obtained after filtering out the moisture;

[0065] (4) The multiphase filler masterbatch is dehydrated by three-stage vacuum to obtain the masterbatch. The conditions for three-stage vacuum dehydration are:

[0066] (a) Under a vacuum degree of -0.08 MPa, dry at 80 °C for 10 min;

[0067] (b) Under a vacuum degree of -0.095 MPa, dry at 60 °C for 15 min;

[0068] (c) Under a vacuum degree of -0.1 MPa, dry at 40 °C for 20 min.

[0069] Example 2

[0070] Control the potential values of the carbon black slurry, clay slurry, and silica slurry to be -40 mV, -20 mV, and +20 mV respectively, and the others are the same as in Example 1.

[0071] Example 3

[0072] Control the potential values of the carbon black slurry, clay slurry, and silica slurry to be -30 mV, -10 mV, and +10 mV respectively, and the others are the same as in Example 1.

[0073] Example 4

[0074] The interfacial compatibilizer is KH570, and the others are the same as in Example 1.

[0075] Example 5

[0076] No interfacial compatibilizer is added, and the others are the same as in Example 1.

[0077] Comparative Example 1

[0078] Prepare the three slurries according to Example 1, but do not adjust the pH value of the slurry, that is, do not control the potential values of the carbon black slurry, clay slurry, and silica slurry, and the others are the same as in Example 1.

[0079] Comparative Example 2

[0080] 70 parts of natural rubber, 30 parts of styrene-butadiene rubber, 35 parts of carbon black (N234), 20 parts of silica, 5 parts of organic montmorillonite, 5 parts of zinc oxide, 2 parts of stearic acid and 1 part of antioxidant 4020 were added into an internal mixer for mixing. The starting temperature of mixing was 90 °C, the starting speed was 40 rpm. After mixing was completed, the stock was discharged, and the discharging temperature was about 145 °C. Then, 1.2 parts of accelerator CZ and 2 parts of sulfur were added on an open mill. After mixing evenly, the rubber sheet was taken out. After standing for 8 h, it was vulcanized at 160 °C with a flat vulcanizer to obtain the vulcanizate.

[0081] The masterbatches prepared in each example and Comparative Example 1 were mixed with 5 parts of zinc oxide, 2 parts of stearic acid, 1 part of antioxidant 4020, 1.2 parts of accelerator CZ and 2 parts of sulfur under the same mixing conditions as in Comparative Example 2. After standing for 8 h, it was vulcanized at 160 °C with a flat vulcanizer to obtain the vulcanizate.

[0082] The vulcanizates prepared in each example and comparative example were tested according to the following method, and Table 1 shows the test results:

[0083] (1) Tensile strength: Refer to GB / T 528-2009;

[0084] (2) Tear strength: Refer to GB / T 528-2009;

[0085] (3) DIN abrasion: Refer to GB / T 9867-2008;

[0086] (4) Heat build-up under compression: Refer to GB / T 9867-2008;

[0087] (5) RPA tanδ: Test was carried out using RPA-2000 of Alpha in the United States. The vulcanizate was subjected to strain sweep in the range of 0.28% - 42% at a frequency of 10 Hz and a temperature of 60 °C to test tanδ.

[0088] (6) Shore A hardness: Refer to GB / T 531.1-2008.

[0089] Table 1

[0090]

[0091] It can be seen from the data in Table 1 that Comparative Example 2 is a vulcanizate obtained by mixing fillers with natural rubber and styrene-butadiene rubber through traditional dry mixing, and Examples 1-5 and Comparative Example 1 are masterbatches prepared by wet methods with different treatment methods and then vulcanized to obtain vulcanizates. The data shows that the hardness of the mixed rubber prepared by the dry method is significantly higher than that of the wet method. The hardness of Example 1 is slightly higher, but the difference from other wet method examples is small. However, the tensile strength, tear strength, abrasion resistance and low hysteresis performance of Example 1 are all the best, and the above-mentioned properties of the vulcanizate prepared by wet mixing are significantly better than those of the dry mixing of Comparative Example 2. This is because the filler is fully mixed with the rubber latex in the liquid phase, avoiding the problem of filler agglomeration caused by insufficient mechanical shear force in dry mixing. The carbon black, silica and clay fillers are dispersed in the rubber matrix at the nanoscale, forming a more uniform reinforcement network, reducing stress concentration, and thus bringing higher strength and reducing energy loss and heat generation during dynamic use.

[0092] It should also be noted that Examples 1-3 and Comparative Example 1 are wet mixing under different potential difference conditions. It can be seen that after adjusting the potential difference, the properties of the rubber compounds in Examples 1-3 are significantly better than those of Comparative Example 1. The performance difference between Examples 2 and 3 is small, but it is significantly inferior to Example 1. It can be seen that the potential difference affects the mixing and compatibility of multi-phase fillers, thus bringing about a performance gap.

[0093] Comparisons of the rubber compounds in Examples 1, 4, and 5 with different interfacial compatibilizers show that the performance of the rubber compounds prepared by adding interfacial compatibilizers is better, especially the difference in hysteresis performance is more obvious. The reason is that the addition of the interfacial compatibilizer reduces the van der Waals force between the fillers, prevents agglomeration caused by surface energy differences, and at the same time reduces the interfacial tension, promoting the formation of a stable microphase separation structure (such as nanoscale dispersion) of the multi-phase fillers, thereby improving the mechanical strength and thermal stability of the material.

[0094] The above examples are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that it is still possible to modify the technical solutions described in the foregoing examples, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a masterbatch, characterized in that: The method comprises: mixing carbon black slurry, white carbon black slurry, clay slurry and rubber latex, flocculating, and then drying to obtain a masterbatch, wherein the electric potentials of the white carbon black slurry, clay slurry and carbon black slurry gradually decrease, and the electric potential difference between the two slurries is 10 to 60 mV, preferably 20 to 50 mV.

2. The method according to claim 1, characterized in that The potential value of the carbon black slurry is -30mV to -50mV, the potential value of the white carbon black slurry is +5mV to +20mV, and the potential value of the clay slurry is -10mV to -20mV.

3. The method according to claim 1, characterized in that The method for preparing the carbon black slurry comprises: first stirring carbon black, a coupling agent and water, adjusting the pH with ammonia water, and then performing a first ultrasonic treatment to obtain the carbon black slurry; and / or, The carbon black comprises at least one of N234 carbon black, N110 carbon black, N330 carbon black and N220 carbon black; and / or, The coupling agent includes at least one of Si75, Si69 and KH550; and / or, The mass ratio of the carbon black to the coupling agent is 1:(0.01-0.02); and / or, The first stirring speed is 500-1200 rpm, and the time is 25-30 min; and / or, The solid content of the carbon black slurry is 2 to 8 wt %; and / or, The frequency of the first ultrasound is 35-45 Hz, and the duration is 5-15 min; and / or, The pH of the carbon black slurry is 9-10.

4. The method according to claim 1, characterized in that The method for preparing the white carbon black slurry comprises: performing a second stirring on white carbon black, an ionic liquid and water, and then performing a second ultrasonic treatment to obtain the white carbon black slurry; and / or, The ionic liquid comprises at least one of (BMIM)Cl and [BMIM][BF4]; and / or, The mass ratio of the white carbon black to the ionic liquid is 1:(0.005-0.01); and / or, The second stirring speed is 500-1200 rpm, and the time is 25-30 min; and / or, The frequency of the second ultrasound is 35-45 Hz, and the duration is 15-20 min; and / or, The solid content of the white carbon black slurry is 2-8 wt %.

5. The method according to claim 1, characterized in that The method for preparing the clay slurry comprises: performing a third stirring on clay, a surfactant and water, and then performing a third ultrasonic treatment to obtain the clay slurry; and / or, The clay comprises at least one of montmorillonite and kaolin; and / or, The surfactant comprises at least one of sodium dodecylbenzene sulfonate and KH570; and / or, The mass ratio of the clay and the surfactant is 1:(0.15-0.25); and / or, The third stirring has a rotation speed of 500 to 1200 rpm and a time of 10 to 20 min; and / or, The third ultrasound has a frequency of 35-45 Hz and a duration of 5-15 min; and / or, The solid content of the clay slurry is 2-8 wt %.

6. The method according to claim 1, characterized in that During the process of adding the carbon black slurry, white carbon black slurry and clay slurry to the rubber latex respectively, an interfacial compatibilizer is added between the two slurries respectively; and / or, The interface compatibilizer is KH550 and KH570 in a mass ratio of 1: (0.5-1); and / or, The added amount of the interfacial compatibilizer is 1-5 wt % of the total mass of the carbon black slurry, the white carbon black slurry and the clay slurry.

7. The method according to claim 1, characterized in that The mass ratio of the rubber latex to the carbon black slurry, the white carbon black slurry and the clay slurry is 100:(30-40):(15-25):(1-35); and / or, The rubber comprises at least one of natural rubber and styrene-butadiene rubber; and / or, The mixing speed is 500-1200 rpm and the mixing time is 30-35 min; and / or, The drying is a three-stage dehydration, and the three-stage dehydration includes: (a) drying at 78-82°C for 8-10 min under a vacuum degree of -0.08 MPa; (b) drying at 58-62° C. for 12-15 min under a vacuum degree of -0.095 MPa; (c) Drying at 38-42°C for 18-20 min under a vacuum degree of -0.1 MPa.

8. A masterbatch, characterized in that: The masterbatch is prepared by the method according to any one of claims 1 to 7.

9. A vulcanized rubber, characterized in that: The vulcanized rubber comprises the masterbatch according to claim 8; and / or, The tensile strength of the vulcanized rubber is 28 to 35 MPa; and / or, The tear strength of the vulcanized rubber is 100 to 120 kN / m; and / or, The DIN abrasion of the vulcanized rubber is 80 to 104 mm3; and / or, The compression heat of the vulcanized rubber is 18-24°C; and / or, The RPAtanδ (60°C) of the vulcanized rubber is 0.090 to 0.125; and / or, The Shore A hardness of the vulcanized rubber is 65-67.

10. Use of the vulcanized rubber according to claim 9 in tire tread rubber or sidewall rubber.

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