Modified high-temperature-resistant fluororubber as well as preparation method and application thereof

Abstract

The invention discloses modified high-temperature-resistant fluororubber as well as a preparation method and application thereof, and belongs to the technical field of fluororubber materials. According to the modified high-temperature-resistant fluororubber provided by the invention, by adding the modified triallyl isocyanurate, the decomposition of the triallyl isocyanurate in the fluororubber at a high temperature can be slowed down, so that the high-temperature resistance of the fluororubber is improved. The problem that the long-term mechanical property change rate of fluororubber at 280 DEG C or above is large is solved, the long-term mechanical property stability of ternary peroxide fluororubber in a higher-temperature environment is achieved, and the requirement for high-temperature-resistant fluororubber in the industrial field is met. In addition, the modified triallyl isocyanurate disclosed by the invention is simple in preparation process, low in material cost and easy in process production, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of fluororubber materials, and in particular relates to a modified high-temperature resistant fluororubber and a preparation method and application thereof. Background Art

[0002] In the current field of rubber materials, ternary peroxide fluororubber, as an important type of high-performance rubber, has shown outstanding comprehensive performance. The monomers such as vinylidene fluoride (VDF), tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) in its molecular composition structure give the rubber unique high temperature resistance, pressure resistance and chemical corrosion resistance. In terms of temperature resistance, ternary peroxide fluororubber can be used stably for a long time in an environment of 230°C under normal working conditions.

[0003] However, when the working environment temperature rises and remains in the high temperature range for a long time, the performance degradation problem of ternary peroxide fluororubber gradually becomes prominent. Taking the tensile strength, a key mechanical performance indicator, as an example, after the temperature exceeds 250°C, its tensile strength shows a relatively obvious downward trend as time goes by. In terms of hardness, high temperature will also have an impact on it, causing the rubber hardness to increase, thereby reducing the flexibility of the material. In some application scenarios that require frequent dynamic deformation, this change in hardness may cause the material to fail prematurely. As the use time increases, obvious cracks will appear on the surface of the material, which may cause the sealing life of sealing products to be greatly shortened.

[0004] Triallyl isocyanurate is mainly used as a crosslinking and modifier for polyolefins, a vulcanizing agent for special rubbers, a crosslinking agent for unsaturated polyester fiberglass, and an internal plasticizer for polystyrene. It is relatively stable at room temperature, but it is easy to decompose under high temperature, strong acid, strong alkali and other conditions, releasing toxic gases. In fluororubber materials, triallyl isocyanurate is the weak point of crosslinking at high temperature and is also the most easily decomposed structural point.

[0005] In high-end application fields, the requirements for material performance are extremely stringent. For example, in the aerospace field, the sealing components around the aircraft engine need to withstand complex and changing temperature environments during different stages such as engine startup, cruising and landing. Once the material performance is excessively attenuated and the seal fails, it will directly threaten flight safety. Therefore, in order to meet the growing demand in these high-end application fields, it is urgent to modify the ternary peroxy fluororubber to withstand higher temperatures, which is of vital significance for improving the product performance, reliability and safety in related fields. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the object of the present invention is to provide a modified high temperature resistant fluororubber and a preparation method and use thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The invention provides a modified triallyl isocyanurate. The modified triallyl isocyanurate is prepared by using triallyl isocyanurate, polyimide and an adsorbent as raw materials. The mass ratio of the triallyl isocyanurate, polyimide and the adsorbent is 6:(1-10):(0.1-1).

[0009] Furthermore, the mass ratio of triallyl isocyanurate, polyimide and adsorbent is 6:3:1; and the adsorbent is white carbon black.

[0010] The present invention also provides a preparation method of the modified triallyl isocyanurate, which comprises uniformly mixing triallyl isocyanurate and polyimide, adding an adsorbent, and grinding to obtain the modified triallyl isocyanurate.

[0011] Furthermore, the grinding is spheroidal graphite, the rotation speed of the spheroidal graphite is 100-1000rpm, and the ball milling time is 2-50min.

[0012] Furthermore, the rotation speed of the spheroidal graphite is 300-450rpm, and the ball milling time is 5-25min.

[0013] The present invention also provides a modified fluororubber, which is prepared using fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent as raw materials, and the mass ratio of the fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent is (50-200):(1-10):(10-60):(0.1-5):(0.1-10):(0.1-10); the vulcanizing agent is the above-mentioned modified triallyl isocyanurate.

[0014] Furthermore, the mass ratio of the fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent is 100:5:30:1:3:4; the fluororubber raw rubber is ternary peroxide fluororubber raw rubber, the acid absorber is at least one of zinc oxide and magnesium oxide, the filler is at least one of carbon black, diatomaceous earth, barium sulfate and kaolin, and the vulcanizer is at least one of 2,5-di-tert-butyl peroxide-2,5-dimethylethane and 2,4-di-tert-butyl peroxide isopropylbenzene.

[0015] The present invention also provides a preparation method of the modified fluororubber, which comprises mixing fluororubber raw rubber, an acid absorber, a filler, an internal mold release agent, a vulcanizing agent and a vulcanizing agent together to obtain a fluororubber mixed rubber; stopping, re-mixing, first-stage vulcanization, and second-stage vulcanization to obtain the modified fluororubber.

[0016] Furthermore, the parking temperature is 10-40°C, and the parking time is 10-50h; the one-stage vulcanization process is a pressure of 15MPa, a temperature of 180°C, and a time of 5min; the two-stage vulcanization process is a temperature of 230°C and a time of 4-18h.

[0017] The present invention also provides the use of the modified triallyl isocyanurate and modified fluororubber in preparing high temperature resistant rubber materials.

[0018] The present invention has achieved the following beneficial effects:

[0019] The present invention provides a modified high temperature resistant fluororubber, which can slow down the decomposition of triallyl isocyanurate in fluororubber at high temperature by adding modified triallyl isocyanurate, thereby improving the high temperature resistance of fluororubber. The present invention solves the problem of large change rate of long-term mechanical properties in fluororubber at 280°C and above, realizes the long-term stability of mechanical properties of ternary peroxide fluororubber in a higher temperature environment, and meets the demand for high temperature resistant fluororubber in the industrial field. In addition, the modified triallyl isocyanurate of the present invention has a simple preparation process, low material cost, and is easy to process production, and has broad application prospects.

[0020] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0021] The above contents of the present invention are further described in detail below through specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. DETAILED DESCRIPTION

[0022] The raw materials and equipment used in the present invention are all known products, which are obtained by purchasing commercially available products.

[0023] The following experiments without any explanation of temperature are reactions under normal temperature conditions, where normal temperature is room temperature, which is 25±5℃.

[0024] The white carbon black used in the specific implementation is a gas phase hydrophilic white carbon black with a specific surface area of ​​about 380 m 2 / g.

[0025] Example 1: Preparation of modified fluororubber 1

[0026] (1) Add triallyl isocyanurate and polyimide to a beaker and stir thoroughly to disperse the polyimide evenly in the triallyl isocyanurate. Add white carbon black to the mixture of triallyl isocyanurate and polyimide (the mass ratio of triallyl isocyanurate, polyimide and white carbon black is 6:3:1), and mill in a ball mill at a speed of 300-450 rpm for 5-25 minutes to allow the mixture of triallyl isocyanurate and polyimide to be fully adsorbed on the white carbon black to obtain modified triallyl isocyanurate.

[0027] (2) When preparing a fluororubber compound, by weight, 100 parts of ternary peroxide fluororubber raw rubber, 5 parts of acid absorbent, 30 parts of filler, 1 part of internal mold release agent, 3 parts of vulcanizing agent, and 4 parts of vulcanizing agent are used. The ternary peroxide fluororubber raw rubber is a ternary peroxide type fluororubber composed of three monomers: vinylidene fluoride (VDF), tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), with a fluorine content of 66-69% and Mooney 17; the acid absorbent is zinc oxide, the filler is carbon black, the vulcanizing agent is 2,5-di-tert-butylperoxy-2,5-dimethylethane, and the vulcanizing agent is the modified triallyl isocyanurate obtained in step (1).

[0028] The ternary peroxide fluororubber raw rubber, acid absorber, filler, internal release agent, vulcanizer and vulcanizing agent were put into an internal mixer and mixed at room temperature for 5 minutes. Then, the mixing mill was opened with a roller distance of 3mm for mixing 2 to 3 times, and then the roller distance was reduced to 1mm for thin pass, and 4 to 8 triangular packages were turned over. Finally, the roller distance was adjusted back to 3mm to sheet the rubber to obtain peroxide fluororubber mixed rubber.

[0029] The peroxide fluorine compound rubber needs to be left at room temperature for 24 hours, then mixed 2 to 3 times with a roller distance of 3mm on the mixing mill, and then the roller distance is reduced to 1mm for thin pass, and 4 to 8 triangular packages are turned over, and then the roller distance is adjusted back to 3mm to sheet the peroxide fluorine compound rubber, and then the first and second stage vulcanization are carried out in sequence to obtain modified fluororubber 1.

[0030] The first stage vulcanization conditions are 15MPa pressure, 180℃ and 5min; the second stage vulcanization conditions are 230℃ and 4-18h.

[0031] Example 2: Preparation of modified fluororubber 2

[0032] The preparation method of Example 1 is referred to, except that the vulcanizing agent 2,5-di-tert-butylperoxide-2,5-dimethylethane is replaced by 2,4-di-tert-butylperoxide isopropylbenzene, to obtain modified fluororubber 2.

[0033] Example 3: Preparation of modified fluororubber 3

[0034] The preparation method of Example 1 is referred to, except that the acid absorber is replaced by magnesium oxide, and the vulcanizing agent 2,5-di-tert-butylperoxide-2,5-dimethylethane is replaced by 2,4-di-tert-butylperoxide isopropylbenzene, to obtain modified fluororubber 3.

[0035] The following is the preparation method of the control sample.

[0036] Comparative Example 1: Preparation of unmodified fluororubber

[0037] The preparation method of Example 1 is referred to, except that the triallyl isocyanurate modified by the vulcanizing agent is replaced by triallyl isocyanurate not modified by polyimide, so as to obtain unmodified fluororubber.

[0038] The beneficial effects of the present invention are demonstrated by experimental examples below.

[0039] Experimental Example 1: Properties of the modified fluororubber of the present invention

[0040] In order to verify the heat aging performance of the modified fluororubber of the present invention, the fluororubber obtained in Examples 1-3 and Comparative Example 1 was made into test pieces and aged at 280°C for 3d (d: day) and 5d, respectively. The fluororubber test pieces before and after aging were subjected to tensile tests according to GB / T 528-2009.

[0041] Table 1 Thermal aging properties of modified fluororubber of the present invention

[0042]

[0043] The experimental test results are shown in Table 1: Comparing the fluororubbers obtained in Examples 1-3 and Comparative Example 1, the hardness change rate and the mechanical property change rate of the fluororubber before and after aging are significantly reduced by adding modified triallyl isocyanurate compared to adding triallyl isocyanurate that is not modified by polyimide. Among them, further comparing Examples 1-3, the hardness change rate and the tensile strength change rate of the fluororubber obtained in Example 1 are the smallest before and after aging. The fluororubber obtained in Comparative Example 1 has cracks on the surface of the material after three days of pressurized high-temperature aging, while the fluororubber obtained in Examples 1-3 has no cracks on the surface, indicating that the modified triallyl isocyanurate of the present invention can slow down the destruction of triallyl isocyanurate as a weak point of the cross-linked network structure at high temperature, thereby reducing the mechanical property change rate of the fluororubber material before and after high-temperature aging.

[0044] In summary, the present invention provides a modified high temperature resistant fluororubber, which can slow down the decomposition of triallyl isocyanurate in fluororubber at high temperature by adding modified triallyl isocyanurate, thereby improving the high temperature resistance of fluororubber. The present invention solves the problem of large change rate of long-term mechanical properties in fluororubber at 280°C and above, realizes the long-term stability of mechanical properties of ternary peroxide fluororubber in a higher temperature environment, and meets the demand for high temperature resistant fluororubber in the industrial field. In addition, the modified triallyl isocyanurate of the present invention has a simple preparation process, low material cost, and is easy to process production, and has broad application prospects.

Claims

1. A modified triallyl isocyanurate, characterized in that: The modified triallyl isocyanurate is prepared by using triallyl isocyanurate, polyimide and adsorbent as raw materials, and the mass ratio of the triallyl isocyanurate, polyimide and adsorbent is 6:(1-10):(0.1-1).

2. The modified triallyl isocyanurate according to claim 1, characterized in that: The mass ratio of triallyl isocyanurate, polyimide and adsorbent is 6:3:1; and the adsorbent is white carbon black.

3. The method for preparing the modified triallyl isocyanurate according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: uniformly mixing triallyl isocyanurate and polyimide, adding an adsorbent, and grinding to obtain the modified triallyl isocyanurate.

4. The preparation method according to claim 3, characterized in that: The grinding is spheroidal graphite, the rotation speed of the spheroidal graphite is 100-1000rpm, and the ball milling time is 2-50min; preferably, the rotation speed of the spheroidal graphite is 300-450rpm, and the ball milling time is 5-25min.

5. A modified fluororubber, characterized in that: The modified fluororubber is prepared from fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent as raw materials, and the mass ratio of the fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent is (50-200):(1-10):(10-60):(0.1-5):(0.1-10):(0.1-10); the vulcanizing agent is the modified triallyl isocyanurate according to claim 1 or 2.

6. The modified fluororubber according to claim 5, characterized in that: The mass ratio of the fluororubber raw rubber, acid absorber, filler, internal mold release agent, vulcanizer and vulcanizing agent is 100:5:30:1:3:4; the fluororubber raw rubber is ternary peroxide fluororubber raw rubber, the acid absorber is at least one of zinc oxide and magnesium oxide, the filler is at least one of carbon black, diatomaceous earth, barium sulfate and kaolin, and the vulcanizer is at least one of 2,5-di-tert-butyl peroxide-2,5-dimethylethane and 2,4-di-tert-butyl peroxide isopropylbenzene.

7. The method for preparing the modified fluororubber according to claim 5 or 6, characterized in that: The preparation method comprises the following steps: mixing fluororubber raw rubber, an acid absorber, a filler, an internal mold release agent, a vulcanizing agent and a vulcanizing aid together to obtain a fluororubber mixed rubber; stopping, re-mixing, first-stage vulcanization and second-stage vulcanization to obtain the modified fluororubber.

8. The preparation method according to claim 7, characterized in that: The parking temperature is 10-40°C, and the parking time is 10-50h; the one-stage vulcanization process is 15MPa pressure, 180°C temperature, and 5min; the two-stage vulcanization process is 230°C temperature and 4-18h.

9. Use of the modified triallyl isocyanurate according to claim 1 or 2 and the modified fluororubber according to claim 5 or 6 in the preparation of high temperature resistant rubber materials.

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