A magnetic encoder nitrile rubber composite material, a preparation method and application thereof

Abstract

The application discloses a nitrile rubber composite material for a magnetic encoder and a preparation method and application thereof, and belongs to the technical fields of rubber compounding, magnetic powder, internal mixing and vulcanization. According to the application, the raw materials of the nitrile rubber composite material for the magnetic encoder include, in terms of weight fractions, 100 parts of nitrile rubber raw rubber, 3-10 parts of zinc oxide, 0.5-4 parts of stearic acid, 0.5-4 parts of an internal rubber release agent, 400-1000 parts of strontium ferrite SrFe 12 O9, 20-60 parts of calcium silicate, 0-30 parts of a plasticizer, 1-10 parts of odorless DCP, 0.5-10 parts of TAIC and 0.5-5 parts of HVA-2. The nitrile rubber composite material has good processing performance and moderate viscosity, and is capable of being quickly mixed in a mixing process, generating moderate heat, being quickly formed into a lump, being quickly filled into a mold cavity in a mold pressing process, and being not prone to defects such as air pockets and flow marks. The nitrile rubber composite material is capable of being smoothly demolded in a mold pressing process at 160-190 DEG C, has high production efficiency and high product qualification rate.

Description

Technical Field

[0001] This invention belongs to the fields of rubber compounding, magnetic powder, mixing and vulcanization technology, and specifically relates to a nitrile rubber composite material for magnetic encoders, its preparation method and application. Background Technology

[0002] With the rapid development of the automotive industry, the requirements for vehicle performance are increasing, especially in terms of safety and intelligence. As a core component for detecting the position or speed of rotating parts, the performance of magnetic encoders directly affects the accuracy and reliability of vehicle speed monitoring. Currently, accuracy and resolution are inherent weaknesses in vehicle control; for the same volume, the accuracy of on-board magnetic encoders is lower than that of photoelectric encoders. Low-speed signal jitter and zero-point instability can cause problems such as jerking and incorrect speed adjustments in ESP and motor closed-loop control during vehicle crawling, idling, and reversing. Hysteresis characteristics lead to inconsistent physical position output angles during forward and reverse steering, resulting in low accuracy in autonomous driving path tracking and steering centering control. Summary of the Invention

[0003] The purpose of this invention is to provide a nitrile rubber composite material for magnetic encoders, its preparation method, and its application. By adding magnetic powder to nitrile rubber material and controlling the amount, followed by processing, vulcanization molding, and magnetization using a high-shear rubber mixing device, a nitrile rubber composite material for magnetic encoders with required magnetic properties is obtained. This workpiece can meet the magnetic requirements for detecting the position and speed of rotating components, with a surface magnetic field greater than 50 mT for the magnetic ring.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a nitrile rubber composite material for magnetic encoders, comprising, by weight, 100 parts of nitrile rubber raw rubber, 3-10 parts of zinc oxide, 0.5-4 parts of stearic acid, 0.5-4 parts of rubber internal release agent, and strontium ferrite (SrFe). 12 O9400~1000 parts, calcium silicate 20~60 parts, plasticizer 0~30 parts, 1,3-bis(tert-butylperoxyisopropyl)benzene (odorless DCP) 1~10 parts, triallyl isocyanurate (TAIC) 0.5~10 parts and N,N'-m-phenylenebismaleimide (HVA-2) 0.5~5 parts.

[0005] Preferably, the acrylonitrile (ACN) content of the raw nitrile rubber is 28~51wt%, and the Mooney viscosity L1+10 is 45~70 at 100℃.

[0006] If the viscosity of the nitrile rubber raw material used in this invention is too low, its mechanical properties will not be well maintained at 170°C; if the viscosity is too high, its flowability will be insufficient, which is not conducive to rapid mold filling and high-speed, high-efficiency production. Furthermore, it is compatible with the strontium ferrite (SrFe) filler used in this invention.12 O9 also significantly increases viscosity, therefore the initial raw rubber viscosity must be limited to a certain range. Nitrile rubber is selected from raw rubber with medium to high ACN% and high ACN% content (28~51wt%). Compared with raw rubber with medium to low ACN% and low ACN% content, raw rubber with medium to high ACN% and high ACN% content has better oil resistance, heat resistance, and mechanical properties.

[0007] Preferably, the plasticizer is an ether ester-based environmentally friendly plasticizer.

[0008] Preferably, the zinc oxide contains 25% to 35% ZnO.

[0009] Preferably, the rubber release agent is Modified 935P.

[0010] Preferably, the strontium ferrite SrFe 12 The purity of O9 is >99%, the particle size range is 1~8μm, and the proportion of median particle size of 4.0μm~5.5μm is greater than 50wt%.

[0011] SrFe ferrite with the above-mentioned particle size structure 12 After O9 crosslinks with nitrile rubber raw rubber, the molecular chain segments between the crosslinking points have good microscopic matching and strong interaction, especially at a high temperature of 170℃, which can better form a bonded rubber and ensure the comprehensive performance of the product after magnetization.

[0012] The second technical solution of the present invention provides a method for preparing the above-mentioned nitrile rubber composite material for magnetic encoders, comprising the following steps: Nitrile rubber raw material, zinc oxide, stearic acid, rubber internal release agent, and calcium silicate are added to a mixer and mixed. Then, strontium ferrite (SrFe) is added. 12 O9 and plasticizer are further mixed, cleaned, and then discharged and allowed to stand to obtain a compound without vulcanizing agent. The compound without vulcanizing agent is transferred to a two-roll mill and 1,3-bis(tert-butylperoxyisopropyl)benzene, triallyl isocyanurate and N,N'-m-phenylenebismaleimide are added. The mixture is then thinned and sheeted to obtain a compound sheet. The compound sheet is then molded by a molding device and then magnetized to obtain the nitrile rubber composite material for the magnetic encoder.

[0013] Compared with the prior art, the present invention selects heat-resistant nitrile rubber raw rubber and adds magnetic strontium ferrite (SrFe) to the nitrile rubber formulation. 12 O9 employs a high-shear internal mixer to ensure uniform dispersion of the composition during mixing. Furthermore, by screening the magnetic powder particle size and purity, it guarantees both the required magnetic properties of the composite material and excellent oil and heat resistance, thus ensuring the product's lifespan.

[0014] The third technical solution of the present invention provides an application of the above-mentioned nitrile rubber composite material for magnetic encoders in the preparation of magnetic encoders.

[0015] The beneficial technical effects of the present invention are as follows: The nitrile rubber composite material provided by this invention has good processing performance, moderate viscosity, fast powder absorption and moderate heat generation during the mixing process, and fast agglomeration. During the molding process, it fills the mold cavity in a short time and is not prone to defects such as air pockets and flow marks. The nitrile rubber composite material provided is easy to demold during molding at 160~190℃, with high production efficiency and high product qualification rate. Detailed Implementation

[0016] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0017] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0018] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0020] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0021] The nitrile rubber raw material 1052J used in this invention was purchased from Zeon, Japan. Its acrylonitrile content is 33.5 wt%, Mooney viscosity L1+10 is 45 at 100°C.

[0022] The nitrile rubber raw material 1965 used in this invention was purchased from Nandi, with an acrylonitrile content of 19wt%, Mooney viscosity L1+10, and 65 at 100°C.

[0023] The zinc oxide used in this invention was purchased from Guangzhou Aoqinka, and its ZnO content is 30%.

[0024] The stearic acid used in this invention was purchased from Nanchuan International Trade.

[0025] The Modelli 935P used in this invention was purchased from Nanchuan International Trade.

[0026] The strontium ferrite SrFe used in this invention 12 O9 was purchased from Beikuang Magnetic Materials, model BMXF-3D, with SrFe 12 The purity of O9 is >99%, the particle size range is 1~8μm, and the proportion of particles with a median particle size of 4.5μm is 82%.

[0027] The calcium silicate used in this invention was purchased from Nanchuan International Trade Co., Ltd.

[0028] The plasticizer TP-95 used in this invention was purchased from Nanchuan International Trade.

[0029] The odorless DCP used in this invention was purchased from Nanchuan International Trade.

[0030] The crosslinking agent TAIC used in this invention was purchased from Nanchuan International Trade.

[0031] The crosslinking agent HVA-2 used in this invention was purchased from Nanchuan International Trade.

[0032] Examples 1-3 and Comparative Examples 1-2 Preparation of nitrile rubber composite materials: (1) Prepare all raw materials according to the formula in Table 1; (2) The rubber compound was produced using an ML-55L internal mixer. The internal mixer used was from Dalian No. 2 Rubber & Plastics Machinery Co., Ltd., model: X(S)N-55 / 32, with a main motor power of 110KW and a rotor speed (front / back) of 32 / 26r / min. Nitrile rubber raw rubber, zinc oxide, stearic acid, Modelli 935P and calcium silicate were added and mixed for 2 minutes. Then strontium ferrite SrFe was added. 12 O9. Mix the plasticizer for 5 minutes, clean, mix to 120℃ to discharge the glue, let stand, and obtain the unvulcanized rubber compound; after forming a smooth high-roll rubber on the unvulcanized rubber compound on the open mill, add odorless DCP, crosslinking agent TAIC, and crosslinking agent HVA-2, cut left and right, after consuming the powder, triangularly wrap thinly 5 times, roll 3 times, and get the rubber compound sheet.

[0033] (2) Preparation of test pieces and samples: The compounded rubber sheet was vulcanized at 175℃ for 10 minutes on a 50-ton flat vulcanizing machine; it was then vulcanized again at 150℃ for 2 hours to obtain test pieces with a thickness of 0.6±0.1mm. These test pieces were then cut into ring shapes using a special cutter and finally magnetized on a special magnetizing device (MT-25200 magnetizer) (magnetizing voltage adjusted to 1200V) to obtain magnetic nitrile rubber composite material. The performance of the prepared magnetic nitrile rubber composite material was measured, and the results are shown in Table 1.

[0034] Table 1 Note: The strontium ferrite in Comparative Example 1 was not sieved, while Examples 1, 2, 3 and Comparative Example 2 were sieved through a 200-mesh sieve; Comparative Example 2 was subjected to low shear force internal mixing at 2.5 MPa; Examples 1, 2, 3 and Comparative Example 1 were subjected to high shear force internal mixing at 4.5 MPa.

[0035] The data in Table 1 shows that: (1) Comparing Example 1 and Example 2, Example 1 introduced magnetic powder strontium ferrite SrFe into the formulation. 12 O9 gives the rubber the ability to be magnetized, and its surface magnetic strength after magnetization can meet the requirements of actual use; no magnetic powder was added in the formulation of Example 2, so the rubber body could not be made magnetic under the same magnetization conditions.

[0036] (2) Compared with Example 3, both Example 1 and Example 3 contain magnetic powder strontium ferrite (SrFe). 12 O9, and judging from the magnetization results, the magnetic properties can meet the actual use requirements. However, Example 3 uses raw rubber 1965 with low acrylonitrile content, which has significantly worse mechanical strength and heat resistance than Example 1. In environments with long-term high-temperature use, the rubber ages quickly, the hardness changes greatly, the rubber easily loses its elasticity, and eventually loses its function.

[0037] (3) Compared with Comparative Example 1, Example 1 used magnetic powder strontium ferrite (SrFe) that was not sieved. 12 O9, after magnetization, has a lower surface magnetic strength than Example 1, failing to meet the standard requirement of 50mT.

[0038] (4) Compared with Comparative Example 2, Comparative Example 2 uses a low shear force internal mixer. After magnetization, the surface magnetic intensity fluctuates greatly and the magnetic field strength is unstable, which will lead to unstable magnetic induction signal.

[0039] (5) From the overall perspective of Examples 1-3 and Comparative Examples 1-2, the magnetic encoder composite material of Example 1, by selecting heat-resistant nitrile rubber and introducing sieved magnetic powder strontium ferrite SrFe into the formulation, 12O9. Using a high-shear-strength internal mixer for kneading, with the synergistic effect of various conditions, ensures that the nitrile rubber composite material has the required surface magnetic strength and also guarantees the service life of the product. This is the most ideal formula and processing solution.

[0040] Compared with the prior art, the present invention selects heat-resistant nitrile rubber (ACN% 28~51wt%) and adds sieved magnetic powder strontium ferrite SrFe to the nitrile rubber formulation. 12 O9 gives the rubber the ability to be magnetized. It is then further mixed using a high-shear internal mixer to obtain a magnetic, high-temperature resistant, and oil-resistant nitrile rubber composite material.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A nitrile rubber composite material for a magnetic encoder, characterized in that, By weight, the raw materials include: 100 parts nitrile rubber raw rubber, 3-10 parts zinc oxide, 0.5-4 parts stearic acid, 0.5-4 parts rubber internal release agent, and strontium ferrite (SrFe). 12 O9400~1000 parts, calcium silicate 20~60 parts, plasticizer 0~30 parts, 1,3-bis(tert-butylperoxyisopropyl)benzene 1~10 parts, triallyl isocyanurate 0.5~10 parts and N,N'-m-phenylenebismaleimide 0.5~5 parts.

2. The nitrile rubber composite material for magnetic encoders according to claim 1, characterized in that, The acrylonitrile content of the raw nitrile rubber is 28~51wt%, and the Mooney viscosity L1+10 is 45~70 at 100℃.

3. The nitrile rubber composite material for magnetic encoders according to claim 1, characterized in that, The plasticizer is an environmentally friendly ether ester plasticizer.

4. The nitrile rubber composite material for magnetic encoders according to claim 1, characterized in that, The zinc oxide contains 25wt% to 35wt% ZnO.

5. The nitrile rubber composite material for magnetic encoders according to claim 1, characterized in that, The rubber internal release agent is Modeli 935P.

6. The nitrile rubber composite material for magnetic encoders according to claim 1, characterized in that, The strontium ferrite SrFe 12 The purity of O9 is >99%, the particle size range is 1~8μm, and the proportion of median particle size of 4.0μm~5.5μm is greater than 50wt%.

7. A method for preparing a nitrile rubber composite material for a magnetic encoder according to any one of claims 1 to 6, characterized in that, Includes the following steps: Nitrile rubber raw material, zinc oxide, stearic acid, rubber internal release agent, and calcium silicate are added to a mixer and mixed. Then, strontium ferrite (SrFe) is added. 12 O9 and plasticizer are further mixed, cleaned, and then discharged and allowed to stand to obtain a compound without vulcanizing agent. The compound without vulcanizing agent is transferred to a two-roll mill and 1,3-bis(tert-butylperoxyisopropyl)benzene, triallyl isocyanurate and N,N'-m-phenylenebismaleimide are added. The mixture is then thinned and sheeted to obtain a compound sheet. The compound sheet is then molded by a molding device and then magnetized to obtain the nitrile rubber composite material for the magnetic encoder.

8. The use of a nitrile rubber composite material for a magnetic encoder as described in any one of claims 1 to 6 in the manufacture of a magnetic encoder.

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