Process for the preparation of air barriers for tire innerliners

Abstract

This invention provides a method for preparing an air-blocking agent for tire airtight layers, belonging to the field of fine chemical technology. The method includes: Step 1: Raw ore pretreatment, using water washing to remove clay impurities adhering to the ore surface and manually removing associated minerals; Step 2: Coarse crushing, using coarse crushing equipment to crush the raw ore to 80-200 mesh; Step 3: Magnetic separation, using a magnetic separator to remove particles with high iron content from the coarsely crushed raw ore; Step 4: Integrated ultrafine grinding and modification, using a dry grinding process in a pneumatic kinetic energy mill at a temperature of 180-230℃, with the aid of additives, to crush the coarsely crushed raw ore using self-impact and self-friction methods; Step 5: Post-treatment, thoroughly mixing the ultrafine-ground and modified raw ore at a preset temperature and time. This invention effectively improves the grinding precision of black talc powder, enhances its dispersibility and rubber matrix affinity, and effectively removes associated minerals and heavy metal impurities.

Description

[0001] This application is a divisional application of the patent application filed on November 18, 2019, with application number 201911128695.0 and invention title "A method for preparing an air-blocking agent for tire airtight layer using black talc as raw material". Technical Field

[0002] This invention belongs to the technical field of fine chemicals, and particularly relates to a method for preparing an air-blocking agent for tire airtight layers. Background Technology

[0003] Black talc appears black due to the presence of a graphene-like layered structure between its molecular layers. It is a layered magnesium silicate mineral with a Mohs hardness of only 1-1.5, is chemically stable, and resistant to high temperatures and acid / alkali corrosion. The main mineral components of black talc are talc, quartz, calcite, dolomite, and organic carbon. Its main chemical components are magnesium oxide, silicon nitride, calcium oxide, aluminum oxide, and small amounts of iron oxide, sodium oxide, and titanium oxide.

[0004] Black talc's low whiteness significantly limits its applications. Currently, its main use is in the production of high-grade ceramics and glazes after high-temperature calcination for whitening, followed by ultrafine grinding, with prices ranging from 800-1200 yuan / ton. This approach is energy-intensive, produces low-value-added products, and fails to fully utilize black talc resources. Therefore, finding suitable application areas based on the physical and chemical properties of black talc from different regions, and employing appropriate processing methods to preserve its flaky characteristics and produce products with high aspect ratios, is essential for achieving functional, high-value-added, and green applications of black talc.

[0005] The precision of pulverization in existing methods for preparing air-blocking agents for tire airtight layers needs to be improved. It is difficult to remove difficult-to-grind associated minerals and heavy metal impurities, resulting in low product purity. At the same time, the dispersibility and rubber matrix affinity of black talc powder need to be improved. Therefore, it is urgent to develop a method for preparing air-blocking agents for tire airtight layers using black talc as raw material. Summary of the Invention

[0006] In view of the problems existing in the above and / or existing methods for preparing air-blocking agents for tire airtight layers using black talc as raw material, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to provide a method for preparing an air-blocking agent for tire airtight layers, which can effectively improve the grinding precision of black talc powder, as well as its dispersibility and rubber matrix compatibility, while also effectively removing difficult-to-grind associated minerals and heavy metal impurities. The technical solution is as follows:

[0008] To solve the above-mentioned technical problems, according to one aspect of the present invention, a method for preparing an air-blocking agent for a tire airtight layer is provided. The air-blocking agent uses black talc powder as raw material. The fineness of the black talc powder is 5000 mesh, its sheet thickness is in the nanometer range, its average aspect ratio is 30-40, and its specific surface area is 14m². 2 The preparation method includes:

[0009] Step 1: Raw ore pretreatment, which includes two steps: washing and screening. Washing is used to remove clay impurities attached to the surface of the raw ore. Screening is a manual process to remove associated minerals (such as quartz, calcite, dolomite, magnetite, etc.).

[0010] Step 2: Coarse crushing, using coarse crushing equipment to crush the raw ore to 80-200 mesh;

[0011] Step 3: Magnetic separation, using a magnetic separator to remove particles with high iron content from the coarsely crushed raw ore;

[0012] Step 4: Integrated ultrafine grinding and modification. In a pneumatic kinetic mill with an internal temperature of 180-230℃, the raw ore after coarse crushing is ground using a dry grinding process with the help of additives. The ore is then ground by self-impact and self-friction. Rapid evaporation of water between the talc layers is used for rapid delamination. The black talc powder is then in-situ composite modified using additives in an integrated grinding and modification process to achieve the dual effects of coupling and dispersion. The additives are any one or any combination of silane coupling agents, aluminate coupling agents, titanate coupling agents, grinding aid coupling agents, rare earth coupling agents, alkali metal fatty acid salts, ammonium polyacrylate, sodium polyacrylate, sodium hexametaphosphate, and sodium tripolyphosphate.

[0013] Step 5: Post-processing. The ultrafine pulverized and modified raw ore is thoroughly mixed at a preset temperature and time to ensure uniform coating and complete reaction of the modifier, and to remove residual water from the raw ore.

[0014] In some embodiments, the bottom of the pneumatic kinetic mill has a slag discharge port to remove difficult-to-crush associated minerals, and the slag discharge rate can be controlled by a high-temperature resistant rotary discharge valve.

[0015] In some embodiments, the high-temperature compressed superheated gas flow used in the pneumatic kinetic mill has a pressure of 0.5-1 MPa and a temperature of 250-320°C.

[0016] In some embodiments, the additive is sprayed into the top of the mill by an atomizing nozzle, and 4-8 atomizing nozzles are evenly distributed on the top of the pneumatic kinetic mill.

[0017] In some embodiments, the amount of additive is 0.3-1.5% of the total mass of black talc powder, and the coarsely crushed raw ore is pulverized to 1250-5000 mesh under the action of the additive.

[0018] In some embodiments, the top of the pneumatic kinetic mill is provided with 1-6 classifiers, the rotation speed of which is adjustable in the range of 100-4500 rpm to control the particle size of the pulverized raw ore.

[0019] In some embodiments, the coarse crushing equipment is any two or more of the following: jaw crusher, roller press, impact hammer crusher, cone crusher, Raymond mill, and vertical mill.

[0020] In some embodiments, the magnetic field strength of the magnetic separator is adjustable, and the magnetic separation controls the iron content of the coarsely crushed raw ore to 0.1-1%.

[0021] In some embodiments, a high-speed mixer is used for post-processing, with a preset temperature of 80-120°C and a preset time of 3-15 minutes.

[0022] The method for preparing an air-blocking agent for a tire airtight layer provided by the embodiments of the present invention has at least one or a portion of the following advantages:

[0023] (1) Using air kinetic energy mill and dry crushing process, the raw ore (black talc raw material) is crushed by self-impact and self-friction at a higher temperature, and the rapid evaporation of water between talc layers is used for rapid flake removal. The crushing efficiency is high, the energy consumption is low, and the sample after crushing has a complete flake structure, a large aspect ratio, and fine particle size with a narrow distribution.

[0024] (2) Through the integrated process of crushing and modification, black talc powder is in-situ composite modified at high temperature, which shortens the process flow and greatly improves the modification effect and crushing efficiency, achieving the dual effects of coupling and dispersion.

[0025] (3) By using magnetic separation and slag removal processes, difficult-to-grind associated minerals and heavy metal impurities are removed, thus improving product purity;

[0026] (4) The ultrafine modified black talc powder produced by this preparation method and process can reach a fineness of 5000 mesh, a layer thickness of nanometer scale, an average aspect ratio of about 30-40, and a specific surface area of ​​up to 14m². 2 Furthermore, it exhibits excellent dispersibility and good affinity with the rubber matrix, and its application in tire airtight layers can provide excellent airtightness and certain reinforcing properties. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 This is a 40,000x magnified SEM image of the product obtained in Embodiment 1 of the present invention;

[0029] Figure 2 The contact angle of the product obtained in Embodiment 1 of the present invention;

[0030] Figure 3 This is a diameter-to-thickness ratio distribution diagram of the product obtained in Embodiment 1 of the present invention. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] This invention provides a method for preparing an air-blocking agent for tire airtight layers.

[0035] Example 1

[0036] A method for preparing an air-blocking agent for tire airtight layers using black talc as a raw material includes the following steps:

[0037] (1) Pretreatment of raw ore: After washing the blocky raw ore with water, the associated minerals such as quartz, calcite, dolomite, and magnetite are manually removed, while the raw ore with high talc content and good platy structure is retained.

[0038] (2) Coarse crushing: The raw ore is coarsely crushed to 2-5cm using a jaw crusher, then crushed to 2-5mm using a roller crusher, and finally crushed to 80 mesh using a Raymond mill.

[0039] (3) Magnetic separation: An electromagnetic dry automatic magnetic separator is used to screen the coarsely crushed material under a magnetic field strength of 12000GS. The iron oxide content in the material after magnetic separation is 0.05%.

[0040] (4) Ultrafine grinding and modification integration: The gas kinetic energy mill uses a superheated airflow of 0.7MPa and 290℃, with the classifier speed at 3200rpm, the slag discharge port fully open, and the dosage of silane coupling agent (KH580) 0.5%, sodium polyacrylate 0.2%, and aluminate coupling agent 0.3% to perform ultrafine grinding and modification treatment on the coarsely crushed material.

[0041] (5) Post-processing: The ultrafine pulverized and modified material was processed for 8 minutes in a high-speed mixer at 1500 rpm and 110°C.

[0042] After post-processing, the powder material is fed into the finished product silo and packaged by an automatic packaging machine to obtain the air-blocking agent for the tire airtight layer. The physicochemical properties of the product obtained in Example 1 are shown in Table 1.

[0043] Table 1. Physical and chemical properties of the product

[0044]

[0045] Example 2

[0046] Using the product prepared in Example 1, an air tightness test was conducted in brominated butyl rubber with different amounts of air barrier agent.

[0047] The rubber formulation is as follows: brominated butyl rubber (100 parts), stearic acid (1 part), naphthenic oil V700 (9 parts), sulfur (1 part), zinc oxide (3.5 parts), accelerator DM (1.3 parts), homogenizer (7 parts), resin (4 parts), and air-blocking agents (30, 40, 50, and 60 parts). A single-stage mixing process was used, where the raw materials were sequentially added to a Banbury mixer and mixed thoroughly. Then, the mixture was passed through a two-roll mill three times in a triangular pattern and three times in a thin pass. After standing for 6 hours, it was vulcanized for 20 minutes at 15 MPa using a flat vulcanizing apparatus. After vulcanization and molding, the air tightness was tested after standing for 24 hours. The air tightness of the samples is shown in Table 2.

[0048] Table 2 Relationship between air barrier dosage and air permeability in brominated butyl rubber

[0049]

[0050] Example 3

[0051] The product prepared in Example 1 was used to conduct air tightness tests on styrene-butadiene rubber (SBR) with different amounts of air barrier agent. The rubber formulation was: SBR (100 parts), stearic acid (1 part), sulfur (1.75 parts), zinc oxide (3 parts), accelerator NS (1 part), and air barrier agent (30, 40, 50, and 60 parts). A single-stage mixing process was used, where the raw materials were sequentially added to a Banbury mixer and mixed thoroughly. Then, the mixture was passed through a two-roll mill three times in a triangular pattern and three times in a thin pass. After standing for 6 hours, it was vulcanized for 17 minutes at 15 MPa using a flat vulcanizing apparatus. After vulcanization and molding, the air tightness was tested after standing for 24 hours. The air tightness of the samples is shown in Table 3.

[0052] Table 3 Relationship between air barrier dosage and air permeability in styrene-butadiene rubber

[0053]

[0054] In summary, the method for preparing an air-blocking agent for tire airtight layers using black talc as raw material can effectively improve the pulverization precision of black talc powder, enhance the dispersibility and rubber matrix affinity of black talc powder, and effectively remove difficult-to-grind associated minerals and heavy metal impurities, thus achieving good economic benefits.

[0055] The method for preparing an air-blocking agent for a tire airtight layer provided by the embodiments of the present invention has at least one or a portion of the following advantages:

[0056] (1) Using air kinetic energy mill and dry crushing process, the raw ore (black talc raw material) is crushed by self-impact and self-friction at a higher temperature, and the rapid evaporation of water between talc layers is used for rapid flake removal. The crushing efficiency is high, the energy consumption is low, and the sample after crushing has a complete flake structure, a large aspect ratio, and fine particle size with a narrow distribution.

[0057] (2) Through the integrated process of crushing and modification, black talc powder is in-situ composite modified at high temperature, which shortens the process flow and greatly improves the modification effect and crushing efficiency, achieving the dual effects of coupling and dispersion.

[0058] (3) By using magnetic separation and slag removal processes, difficult-to-grind associated minerals and heavy metal impurities are removed, thus improving product purity;

[0059] (4) The ultrafine modified black talc powder produced by this preparation method and process can reach a fineness of 5000 mesh, a layer thickness of nanometer scale, an average aspect ratio of about 30-40, and a specific surface area of ​​up to 14m². 2 Furthermore, it exhibits excellent dispersibility and good affinity with the rubber matrix, and its application in tire airtight layers can provide excellent airtightness and certain reinforcing properties.

[0060] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing an air-blocking agent for a tire airtight layer, wherein the air-blocking agent uses black talc powder as raw material, the black talc powder having a fineness of 5000 mesh, a sheet thickness in the nanometer range, an average aspect ratio of 30-40, and a specific surface area of ​​14 m². 2 Its characteristics are, The preparation method includes: Step 1: Raw ore pretreatment, including two steps: water washing and screening. The water washing method is used to remove clay impurities attached to the surface of the raw ore, and the screening method is to manually remove associated minerals. Step 2: Coarse crushing, using coarse crushing equipment to crush the raw ore to 80-200 mesh; Step 3: Magnetic separation, using a magnetic separator to remove particles with high iron content from the coarsely crushed raw ore; Step 4: Integrated ultrafine grinding and modification. In a pneumatic kinetic mill with an internal temperature of 180-230℃, a dry grinding process is used to grind the coarsely crushed raw ore using self-impact and self-friction under the action of additives. Rapid delamination is achieved by utilizing the rapid evaporation of water between talc layers. The black talc powder is then in-situ composite modified using the additives in the integrated grinding and modification process to achieve the dual effects of coupling and dispersion. The additives are any one or any combination of silane coupling agents, aluminate coupling agents, titanate coupling agents, grinding aid coupling agents, rare earth coupling agents, alkali metal fatty acid salts, ammonium polyacrylate, sodium polyacrylate, sodium hexametaphosphate, and sodium tripolyphosphate. Step 5: Post-processing. The ultrafine pulverized and modified raw ore is thoroughly mixed at a preset temperature and time to ensure uniform coating and complete reaction of the modifier, and to remove residual water from the raw ore.

2. The preparation method according to claim 1, characterized in that, The pneumatic kinetic mill has a slag discharge port at the bottom to remove difficult-to-crush associated minerals. The amount of slag discharged from the slag discharge port can be controlled by a high-temperature resistant rotary unloading valve.

3. The preparation method according to claim 2, characterized in that, The high-temperature compressed superheated gas flow used in the pneumatic kinetic mill has a pressure of 0.5-1 MPa and a temperature of 250-320℃.

4. The preparation method according to claim 2, characterized in that, The additive is sprayed into the top of the mill by an atomizing nozzle, and 4-8 of the atomizing nozzles are evenly distributed on the top of the pneumatic kinetic mill.

5. The preparation method according to claim 4, characterized in that, The amount of the additive is 0.3-1.5% of the total mass of the black talc powder. Under the action of the additive, the coarsely crushed raw ore is pulverized to 1250-5000 mesh.

6. The preparation method according to claim 2, characterized in that, The top of the pneumatic kinetic mill is equipped with 1-6 classifiers, the rotation speed of which is adjustable within the range of 100-4500 rpm to control the particle size of the crushed raw ore.

7. The preparation method according to any one of claims 1-6, characterized in that, The coarse crushing equipment is any two or more of the following: jaw crusher, roller press, impact hammer crusher, cone crusher, Raymond mill, and vertical mill.

8. The preparation method according to claim 7, characterized in that, The magnetic field strength of the magnetic separator is adjustable, and the magnetic separation controls the iron content of the coarsely crushed raw ore to 0.1-1%.

9. The preparation method according to claim 7, characterized in that, The post-processing uses a high-speed mixer, and the preset temperature for the post-processing is 80-120℃, and the preset time is 3-15min.

Images