Halogen-free environment-friendly heat-resistant aging-resistant rubber magnetic stripe and preparation method thereof

Abstract

This application relates to the field of flexible composite permanent magnet materials, and discloses a halogen-free, environmentally friendly, heat-resistant, and age-resistant rubber magnetic strip and its preparation method. The halogen-free, environmentally friendly, and age-resistant rubber magnetic strip is prepared from the following raw materials in parts by weight: 85-92 parts magnetic powder; 7-10 parts NBR rubber; 1.5-2.5 parts plasticizer; 1-2 parts dispersant; 0.5-1 part tackifier; 0.05-0.1 part lubricant; 0.5-1 part antioxidant; and 0.05-0.1 part vulcanizing agent. The plasticizer is composed of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalate. The rubber magnetic strip prepared by this application through kneading and dispersion, mixing, calendering, and hot vulcanization, when used in cooling fans, exhibits good halogen-free and environmentally friendly properties. It also demonstrates good heat aging resistance during long-term use in high-temperature environments, is less prone to hardening and cracking, and exhibits good magnetic property stability.

Description

Technical Field

[0001] This application relates to the field of flexible composite permanent magnet materials, and in particular to a halogen-free, environmentally friendly, heat-resistant, and age-resistant rubber magnetic strip and its preparation method. Background Technology

[0002] Rubber magnetic strips are flexible composite permanent magnet materials made from magnetic powder and rubber binder through extrusion or calendering processes. They combine the properties of magnetic powder and rubber, possessing both good magnetic properties and good flexibility, and are widely used in the field of micro fans.

[0003] When in use, the rubber magnetic strip is bent into a ring and attached to the rotor of the cooling fan. During operation, it generates an electromagnetic effect with the stator, thereby driving the cooling fan to rotate and achieve heat dissipation. The cooling fan operates in a high-temperature environment and also generates heat during operation. Therefore, the rubber magnetic strip needs to be able to operate stably for extended periods in temperatures ranging from -40℃ to 100℃.

[0004] To achieve halogen-free and environmentally friendly performance, existing rubber magnetic strips generally use NBR rubber as a rubber adhesive, combined with trace amounts of other additives to bond the magnetic powder. However, the magnetic powder content in rubber magnetic strips typically needs to reach 85-95%. Although NBR rubber has good bonding stability for large amounts of magnetic powder, its high viscosity necessitates the addition of plasticizers for softening during processing. Common plasticizers include dibutyl phthalate (DBP), dioctyl phthalate (DOP), paraffin oil, and naphthenic oil. Under long-term high-temperature environments, the plasticizers in the rubber magnetic strips made with these plasticizers are prone to precipitation, leading to weight loss, hardening, and even cracking, further resulting in a permanent decline in the magnetic properties of the rubber magnetic strips. Summary of the Invention

[0005] To address the problem that existing rubber magnetic strips used in cooling fans are prone to plasticizer decomposition or precipitation under long-term high-temperature environments, resulting in weight loss, hardening, cracking, and permanent degradation of magnetic properties, this application provides a halogen-free, environmentally friendly, heat-resistant, and age-resistant rubber magnetic strip and its preparation method.

[0006] Firstly, this application provides a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip, employing the following technical solution: A halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip is made from the following raw materials in parts by weight: 85-92 parts of magnetic powder; 7-10 parts of NBR rubber; Plasticizer 1.5-2.5 parts; 1-2 parts of dispersant 0.5-1 part tackifier; Lubricant 0.05-0.1 parts; Anti-aging agent 0.5-1 part; Vulcanizing agent 0.05-0.1 parts; The plasticizer is composed of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid ester.

[0007] By employing the above technical solutions, a high dosage of magnetic powder imparts excellent magnetic properties to the rubber magnetic strip; NBR rubber, acting as a binder for the magnetic powder, gives the rubber magnetic strip flexibility and processability; the plasticizer can fully penetrate and disperse into the rubber system, further synergistically improving the toughness of the rubber system with the dispersant; and the selection of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalate as synergistic plasticizers not only enhances the high-temperature aging resistance of the rubber magnetic strip but also prevents it from precipitating and migrating from the rubber magnetic strip, thus enabling the rubber magnetic strip to maintain good toughness and magnetic properties under long-term thermal aging conditions; the dispersant can improve the interfacial phase between the magnetic powder and NBR rubber. The dispersant's compatibility allows the magnetic powder to be fully and uniformly dispersed in the NBR rubber bonding system, improving the agglomeration of the magnetic powder. Simultaneously, the dispersant can interweave and disperse with the molecular chains of the NBR rubber, further improving the flexibility of the rubber magnetic strip. This allows the rubber magnetic strip to maintain good toughness under long-term high-temperature environments, making it less prone to cracking or breakage. It also synergistically reduces the precipitation and migration of plasticizers. The tackifier further enhances the adhesion of the magnetic powder; the lubricant improves the processing stability and surface quality of the rubber magnetic strip; the antioxidant further enhances the heat aging resistance of the rubber magnetic strip; and the vulcanizing agent crosslinks with the rubber system, improving the cohesion and flexibility of the resulting rubber magnetic strip.

[0008] The rubber magnetic strip prepared in this application is halogen-free and environmentally friendly. When used in a long-term high-temperature environment, it is not easy for plasticizers to migrate and precipitate. The rubber magnetic strip is not prone to weight loss, hardening or even cracking, and has good magnetic property stability.

[0009] Preferably, the weight ratio of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid ester is (1-1.5):1:(0.2-0.5).

[0010] By adopting the above technical solution and optimizing the ratio of the three components, polypentylene glycol sebacate and dioctyl adipate are used as the main plasticizer components, which can be fully penetrated and dispersed into the rubber system, optimizing the processing and molding stability of the rubber system, and enhancing the excellent low volatility and anti-migration properties of the rubber magnetic strip. In addition, a small amount of dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalate is added to give the rubber system excellent thermal stability. The three components work synergistically to achieve extremely low heating weight loss, excellent heat aging resistance and long-term durability without sacrificing processability and low-temperature performance.

[0011] Preferably, the magnetic powder is strontium ferrite magnetic powder and / or barium ferrite magnetic powder.

[0012] By adopting the above technical solution, strontium ferrite magnetic powder and / or barium ferrite magnetic powder are used as magnetic powders. These two magnetic powders have good magnetic properties, as well as good high temperature resistance and chemical stability, which enables the rubber magnetic strips to maintain stable magnetic properties under long-term high temperature environment.

[0013] Preferably, the dispersant is composed of diethylenetriaminepropylmethyldimethoxysilane and dodecyl succinic anhydride in a weight ratio of (2-3):1.

[0014] By adopting the above technical solution, diethylenetriaminepropylmethyldimethoxysilane can coat the surface of magnetic powder, reducing the agglomeration force between magnetic powder particles; dodecyl succinic anhydride has a long alkyl chain and anhydride group, which can further interact with the hydroxyl groups on the surface of magnetic powder under high temperature, further increasing the steric hindrance between magnetic powder particles and further preventing the agglomeration of magnetic powder. The two have excellent synergistic effect, ensuring that high content magnetic powder is uniformly and stably dispersed in a small amount of rubber without agglomeration.

[0015] Preferably, the tackifier is a terpene resin and / or rosin resin.

[0016] By adopting the above technical solution and using terpene resin and / or rosin resin as tackifiers, the self-adhesion and formability of magnetic powder can be effectively improved, ensuring the integrity in calendering and other processes, and further improving the thermal stability and performance stability of the obtained rubber magnetic strip.

[0017] Preferably, the lubricant is any one or a combination of calcium stearate, zinc stearate, and ethylene bis-stearamide.

[0018] By adopting the above technical solution, the lubricant has both internal lubrication (reducing intermolecular friction and improving fluidity) and external lubrication (preventing roller sticking), which is suitable for the mixing and calendering process of rubber magnetic strips, ensuring smooth processing, and improving the surface flatness of rubber magnetic strips.

[0019] Preferably, the anti-aging agent is anti-aging agent RD and / or anti-aging agent 4010.

[0020] By adopting the above technical solution, antioxidant RD and / or anti-aging agent 4010 have good compatibility with the rubber system of this application, and can further synergistically and effectively delay the thermo-oxidative aging process of the rubber main chain, thereby maintaining relatively stable flexibility and mechanical strength.

[0021] Preferably, the vulcanizing agent is DCP and / or BIBP.

[0022] By adopting the above technical solution, peroxide vulcanization forms CC crosslinking bonds with high bond energy, which can fully and uniformly crosslink in the system of this application, thereby improving the crosslinking stability of the prepared rubber magnetic strip.

[0023] Secondly, this application provides a method for preparing a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip, using the following technical solution: A method for preparing a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip includes the following steps: S1. Mixing: Add the dispersant to the magnetic powder, knead and disperse to obtain mixture A; add the remaining components to mixture A and mix to obtain the compound. S2. Calendering: Calendering the compound to obtain rubber magnetic sheets; S3. Hot vulcanization: The rubber magnetic sheet is hot vulcanized to obtain halogen-free, environmentally friendly, heat-resistant and aging-resistant rubber magnetic strips.

[0024] By adopting the above technical solution, the mixing step first fully disperses the magnetic powder and dispersant to improve the agglomeration defects of the magnetic powder, and then fully mixes the components to make the different raw materials evenly dispersed; the calendering step processes the compound to give the material a certain shape and size, and improves the flatness and consistency of the material; the hot vulcanization step can make the rubber magnetic sheet vulcanize, further enhancing the thermal stability and magnetic stability of the material.

[0025] Preferably, in step S1, the kneading and dispersion temperature is 120-130℃, the kneading and dispersion time is 30-40 min, the mixing temperature is 100-110℃, and the mixing time is 15-30 min; in step S3, the hot vulcanization temperature is 150-160℃, and the hot vulcanization time is 10-20 min.

[0026] By adopting the above technical solution, the better kneading conditions enable the dispersant to fully disperse the magnetic powder. Then, the mixing is carried out at a lower temperature to make the system fully mixed and uniform and slightly cross-linked. Finally, the system is subjected to hot vulcanization at a higher temperature to make the system fully and uniformly vulcanized. The rubber magnetic strips obtained in this way have better surface smoothness and comprehensive performance.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip of this application is made of specific components of magnetic powder, NBR rubber, plasticizer, dispersant, tackifier, lubricant, antioxidant, and vulcanizing agent. The plasticizer is composed of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid. The resulting rubber magnetic strip has good halogen-free and environmentally friendly properties, can meet the requirements of cooling fans in high-temperature environments, is not prone to plasticizer migration and precipitation, and is not prone to hardening and cracking. It also has good magnetic performance stability.

[0028] 2. The dispersant is composed of diethylenetriaminepropylmethyldimethoxysilane and dodecyl succinic anhydride, which can increase the steric hindrance between magnetic powder particles, further prevent the agglomeration of magnetic powder, and improve the performance stability of rubber magnetic strips.

[0029] 3. Through the preparation steps of kneading and dispersing, mixing, calendering and hot vulcanization, the raw materials can be fully mixed and reacted. The resulting rubber magnetic strips are less prone to plasticizer precipitation, hardening and cracking problems when used in long-term high-temperature environments, and have good magnetic property stability. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the embodiments.

[0031] The following are some of the sources and specifications of the raw materials used in this application. All raw materials used in the embodiments of this application are commercially available, including but not limited to the following models and manufacturers. Raw materials with equivalent performance can also be used: 1. NBR rubber: JSR N240S; 2. Polypentylene glycol sebacic acid ester: molecular weight 3000-5000.

[0032] Example Example 1

[0033] Example 1 discloses a method for preparing a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip, comprising the following steps: S1. Mixing: Add 0.1 kg of dispersant to 8.5 kg of magnetic powder and knead for 40 min at 120℃ to obtain mixture A; add 0.7 kg of NBR rubber, 0.15 kg of plasticizer, 0.1 kg of tackifier, 0.005 kg of lubricant, 0.05 kg of antioxidant and 0.005 kg of vulcanizing agent to mixture A and mix at 100℃ for 30 min to obtain the compound. S2. Calendering: Calendering the compound to obtain rubber magnetic sheets; S3. Hot vulcanization: The rubber magnetic sheet is hot vulcanized at a temperature of 150℃ for 20 minutes to obtain a halogen-free, environmentally friendly, heat-resistant and aging-resistant rubber magnetic strip. In step S1, the dispersant is diethylenetriaminepropylmethyldimethoxysilane, and the magnetic powder is strontium ferrite magnetic powder with a particle size of 0.1µm. The plasticizer is composed of polypentylene glycol sebacate, dioctyl adipate and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid ester in a weight ratio of 1:1:0.2. The tackifier is a terpene resin; the lubricant is calcium stearate; the antioxidant consists of antioxidant RD and antioxidant 4010 in a weight ratio of 2:1; and the vulcanizing agent is DCP.

[0034] Example 2-3 The difference between Examples 2-3 and Example 1 lies in the amount of raw materials used and the preparation conditions, as detailed in Table 1 below.

[0035] Table 1 Parameter table for Examples 1-3

[0036] Example 4

[0037] The difference between Example 4 and Example 3 is that the dispersant is composed of diethylenetriaminepropylmethyldimethoxysilane and dodecyl succinic anhydride in a weight ratio of 2:1, while the rest is the same as in Example 3.

[0038] Example 5

[0039] The difference between Example 5 and Example 3 is that the dispersant is composed of diethylenetriaminepropylmethyldimethoxysilane and dodecyl succinic anhydride in a weight ratio of 3:1, while the rest is the same as in Example 3.

[0040] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that the plasticizer 4,5-epoxytetrahydrophthalic acid dioctyl(2-ethylhexyl) ester was replaced with dioctyl adipate in equal amounts, while the rest was the same as in Example 3.

[0041] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that the polypentylene glycol sebacate in the plasticizer is replaced with an equal amount of dioctyl sebacate, while the rest is the same as in Example 3.

[0042] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that the plasticizer is dioctyl phthalate, while the rest is the same as in Example 3.

[0043] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that the plasticizer is composed of paraffin oil and dioctyl phthalate in a weight ratio of 2:1, while the rest is the same as in Example 3.

[0044] Performance testing The following tests were conducted on the performance of the halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strips prepared in Examples 1-5 and Comparative Examples 1-4: Tested finished product specifications: thickness 2mm; 1. Magnetic stability test The magnetized rubber strip was placed at 100℃ for 24 hours and the remanence reduction rate of the rubber strip was measured (unit: %). A remanence reduction rate of ≤5% was considered qualified. The test results were recorded. 2. Weight loss test due to heating: Place the rubber magnetic strip at 100℃ for 24 hours. After wiping it clean with alcohol, test the weight loss rate of the rubber magnetic strip (unit: %). A weight loss rate of ≤0.5% is considered qualified. Test and record the test results. 3. Mechanical property testing Using a tensile testing machine, dumbbell-shaped specimens were prepared. The initial tensile strength (unit: MPa) of the rubber magnetic strip was tested at a tensile rate of 500 mm / min. After placing the rubber magnetic strip at 85℃ and 85% humidity for 7 days, the tensile strength (unit: MPa) was tested again. The test results were recorded. The following are the performance test data of the halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strips prepared in Examples 1-5 and Comparative Examples 1-4. Please refer to Table 2 below for details.

[0045] Table 2 Performance data of halogen-free, environmentally friendly, heat-resistant, and age-resistant rubber magnetic strips of Examples 1-5 and Comparative Examples 1-4

[0046] Combining Examples 1-3 and 4-5, further optimization of the type and proportion of dispersant can improve the magnetic property stability and thermal aging stability of the prepared rubber magnetic strips. Compared with Example 3, Examples 4-5 show a lower remanence reduction rate, a lower heating weight loss rate, and an increased tensile strength, and the tensile strength reduction rate after damp heat testing is also lower. This may be because the better weight ratio of dispersant improves the uniformity of magnetic powder dispersion in the rubber system.

[0047] In conjunction with Examples 3 and Comparative Examples 1-4, using polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid as plasticizers in specific proportions as described in this application can produce a good synergistic effect with the rubber and magnetic powder dispersion system, improving magnetic property stability and thermal aging stability. In Comparative Examples 1-2, the type of plasticizer was changed, resulting in an increased remanence reduction rate and significantly increased weight loss upon heating of the prepared rubber magnetic strips. Furthermore, the mechanical properties decreased after damp heat testing. In Comparative Examples 3-4, the use of existing plasticizers resulted in a significantly decreased remanence reduction rate and significantly increased weight loss upon heating of the prepared rubber magnetic strips. The mechanical properties also decreased significantly after damp heat testing. This may be because the change in the type and proportion of plasticizers caused precipitation problems in the rubber magnetic strips under long-term thermal aging conditions, leading to hardening and embrittlement.

[0048] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip, characterized in that, It is prepared from the following raw materials in parts by weight: 85-92 parts of magnetic powder; 7-10 parts of NBR rubber; Plasticizer 1.5-2.5 parts; 1-2 parts of dispersant 0.5-1 part tackifier; Lubricant 0.05-0.1 parts; Anti-aging agent 0.5-1 part; Vulcanizing agent 0.05-0.1 parts; The plasticizer is composed of polypentylene glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid ester.

2. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The weight ratio of polypentyl glycol sebacate, dioctyl adipate, and dioctyl (2-ethylhexyl) 4,5-epoxytetrahydrophthalic acid ester is (1-1.5):1:(0.2-0.5).

3. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The magnetic powder is strontium ferrite magnetic powder and / or barium ferrite magnetic powder.

4. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The dispersant is composed of diethylenetriaminepropylmethyldimethoxysilane and dodecyl succinic anhydride in a weight ratio of (2-3):

1.

5. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The tackifier is a terpene resin and / or rosin resin.

6. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The lubricant is any one or a combination of calcium stearate, zinc stearate, and ethylene bis-stearamide.

7. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The anti-aging agent is anti-aging agent RD and / or anti-aging agent 4010.

8. The halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 1, characterized in that, The vulcanizing agent is DCP and / or BIBP.

9. A method for preparing a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Mixing: Add the dispersant to the magnetic powder, knead and disperse to obtain mixture A; add the remaining components to mixture A and mix to obtain the compound. S2. Calendering: Calendering the compound to obtain rubber magnetic sheets; S3. Hot vulcanization: The rubber magnetic sheet is hot vulcanized to obtain halogen-free, environmentally friendly, heat-resistant and aging-resistant rubber magnetic strips.

10. The method for preparing a halogen-free, environmentally friendly, heat-resistant, and aging-resistant rubber magnetic strip according to claim 9, characterized in that, In step S1, the kneading and dispersion temperature is 120-130℃, the kneading and dispersion time is 30-40 min, the mixing temperature is 100-110℃, and the mixing time is 15-30 min; in step S3, the hot vulcanization temperature is 150-160℃, and the hot vulcanization time is 10-20 min.

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