Thermoplastic cross-linked rubber with high-temperature creep resistance as well as preparation method and application of thermoplastic cross-linked rubber

Abstract

The invention discloses high-temperature-creep-resistant thermoplastic cross-linked rubber as well as a preparation method and application thereof, and belongs to the technical field of rubber materials. The preparation method of the high-temperature-creep-resistant thermoplastic crosslinked rubber provided by the invention comprises the following steps: carrying out primary mixing, primary vulcanization and granulation on first raw rubber and a static crosslinking agent to obtain static high-crosslinked rubber particles; and carrying out secondary mixing and secondary vulcanization on second raw rubber, a dynamic crosslinking agent, a filler and the static high-crosslinking rubber particles to obtain the high-temperature creep resistant thermoplastic crosslinking rubber, the first raw rubber and the second raw rubber are the same or different. According to the preparation method, a static / dynamic cross-linked creep-resistant two-phase network structure can be constructed, the static phase in the network structure can limit excessive slippage of a dynamic phase molecular chain based on a steric hindrance effect, collaborative optimization of creep resistance and reprocessing performance is realized, and the preparation method has a wide application prospect in preparation of rubber products.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubber materials, and particularly relates to a high-temperature creep-resistant thermoplastic crosslinked rubber and a preparation method and application thereof. BACKGROUND

[0002] A thermoplastic elastomer (TPE) based on reversible physical crosslinking or dynamic vulcanization can theoretically achieve complete recycling and reprocessing. By implanting dynamic covalent bonds (DCBs) in the crosslinked network, the thermosetting polymer is endowed with dynamic properties such as self-healing and reprocessing. However, dynamic covalent bond crosslinked rubber has an inherent defect compared to traditional vulcanized rubber, i.e., easy creep, which is a fatal shortcoming for crosslinked rubber materials that are used in high-temperature and load conditions for a long time. In order to improve the anti-creep performance of DCB crosslinked polymer materials, researchers have carried out a series of explorations from the aspects of regulating network exchange chemistry and dynamics (J. Am. Chem. Soc., 2019, 141, 16595-16599; Angew. Chem. Int. Ed., 2022, 134, e202113872), network crosslinking structure and phase structure design (Macromolecules, 2018, 51, 5537-5546; Polymer, 2023, 273, 125854), and the like.

[0003] For example, the prior art with the application publication number CN 119775645 A discloses a recyclable inverse vulcanization copolymer vulcanized rubber, which uses a specific inverse vulcanization copolymer such as thioctic acid as a vulcanizing agent, endows the vulcanized rubber network with reprocessing performance, and retains certain anti-creep ability.

[0004] However, the existing modification process has the following problems: first, the introduction of high-activation-energy DCBs has limited improvement in creep performance, and the reprocessing of the material needs to be completed at a higher temperature (>180℃) for a longer time, which can cause serious aging and high processing energy consumption and a series of problems; second, the double crosslinking design based on hydrogen bonds and metal coordination bonds is complex and cumbersome for low-functionalized rubber, often involves multiple-step chemical modification, and easily causes degradation of other properties of the rubber, such as mechanical hysteresis, high fatigue heat generation, and aging; third, the control of the non-uniformity of the DCB concentration and crosslinking density in the network can improve the network anti-creep property, but this method is not suitable for general rubber materials, and has problems such as difficulty in phase regulation and limited anti-creep effect. SUMMARY

[0005] The application discloses a high-temperature creep-resistant thermoplastic crosslinked rubber and a preparation method and application thereof, and aims to solve the technical problems of poor creep performance of existing thermoplastic crosslinked rubber, degradation of other properties, and complicated preparation process.

[0006] To achieve the above object, the technical scheme of the present application is:

[0007] The first aspect of the present application provides a preparation method of a high-temperature creep-resistant thermoplastic crosslinked rubber, the preparation method comprising:

[0008] firstly mixing and vulcanizing the first rubber crumb and the static crosslinking agent, and granulating to obtain static high-crosslinking rubber particles;

[0009] secondly mixing and vulcanizing the second rubber crumb, the dynamic crosslinking agent, the filler and the static high-crosslinking rubber particles to obtain the high-temperature creep-resistant thermoplastic crosslinked rubber;

[0010] The first rubber crumb and the second rubber crumb are the same or different.

[0011] In combination with the first aspect, preferably, the first rubber crumb is one or more of styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene-diene rubber, natural rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized natural rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer, carboxyl nitrile rubber, and carboxyl styrene-butadiene rubber.

[0012] The second rubber crumb is one or more of styrene-butadiene rubber, polybutadiene rubber, ethylene-propylene-diene rubber, natural rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized natural rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer, carboxyl nitrile rubber, and carboxyl styrene-butadiene rubber.

[0013] In combination with the first aspect, preferably, the static crosslinking agent is one or more of effective sulfur vulcanization system, peroxide crosslinking agent, polythiol crosslinking agent, polyamine crosslinking agent, and aziridine crosslinking agent.

[0014] The peroxide crosslinking agent is one or more of dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0015] The polythiol crosslinking agent is one or more of 1,6-hexanedithiol, 1,10-decanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), 1,3,5-trimercapto-2,4,6-triazine, and bis(4-mercaptophenyl)sulfide.

[0016] The polyamine crosslinking agent is one or more of hexanediamine, diethylenetriamine, isophorone diamine, 4,4'-diaminodicyclohexyl methane, p-phenylenediamine, m-phenylenediamine;

[0017] The aziridine crosslinking agent is one or more of trimethylolpropane tris(3-aziridinyl propionate), pentaerythritol tris(3-aziridinyl propionate), trimethylolpropane tris(3-(2-methylaziridinyl) propionate).

[0018] In combination with the first aspect, preferably, the dynamic crosslinking agent is one or more of a benzene boronic acid-containing dimercapto crosslinking agent, a polycarboxylic acid crosslinking agent, a silicon-ether bond-containing dimercapto crosslinking agent, a polyepoxy crosslinking agent;

[0019] The benzene boronic acid-containing dimercapto crosslinking agent is dimercapto-p-phenylenediboronic acid ester;

[0020] The polycarboxylic acid crosslinking agent is one or more of sebacic acid, dimer acid, citric acid, terephthalic acid, butane tetracarboxylic acid;

[0021] The silicon-ether bond-containing dimercapto crosslinking agent is one or more of di(2-mercaptoethyl) silicate, tri(2-mercaptoethyl) silicate, tetra(2-mercaptoethyl) silicate;

[0022] The polyepoxy crosslinking agent is one or more of 1,6-hexane diglycidyl ether, ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether.

[0023] In combination with the first aspect, preferably, the filler includes one or more of carbon black, carbon nanotube, graphene, graphene oxide, white carbon black, calcium carbonate, coal dust.

[0024] In combination with the first aspect, preferably, the primary mixing is banburying or open mixing;

[0025] If banburying is used, the mixing temperature is 30-50°C, the mixing time is 8-15 min; the crosslinking temperature is 140-180°C, and the time is the positive curing time;

[0026] If open mixing is used, the mixing temperature is room temperature, and the mixing time is 5-20 min.

[0027] In combination with the first aspect, preferably, the secondary mixing is banburying or open mixing;

[0028] If banburying is used, the mixing temperature is 30-50°C, the mixing time is 8-15 min; the crosslinking temperature is 140-180°C, and the time is the positive curing time;

[0029] If open mixing is used, the mixing temperature is room temperature, and the mixing time is 5-20 min.

[0030] Preferably in combination with the first aspect, the mass ratio of the first rubber raw rubber and the static crosslinking agent is 100:(0.1-15) during the first mixing, the first vulcanization and the granulation of the first rubber raw rubber and the static crosslinking agent;

[0031] The mass ratio of the second rubber raw rubber, the dynamic crosslinking agent, the filler and the static high crosslinking rubber particles is 100:(0.5-10):(8-150):(10-200) during the second mixing and the second vulcanization of the second rubber raw rubber, the dynamic crosslinking agent, the filler and the static high crosslinking rubber particles.

[0032] The second aspect of the present application provides the thermoplastic crosslinked rubber with high temperature creep resistance prepared by the preparation method of the first aspect.

[0033] The third aspect of the present application provides the application of the thermoplastic crosslinked rubber with high temperature creep resistance of the second aspect in the preparation of rubber products.

[0034] Compared with the prior art, the advantages or beneficial effects of the embodiments of the present application at least include:

[0035] The preparation method provided by the present application introduces the static high crosslinking rubber particles into the dynamically covalently crosslinked rubber by sequential crosslinking to form a static / dynamic crosslinked anti-creep two-phase network structure. The static phase in the network structure can limit the excessive slippage of the dynamic phase molecular chain based on the steric hindrance effect. The static high crosslinking rubber particles can also be introduced into the dynamically crosslinked rubber as an anti-creep unit to transmit stress by interfacial force and prevent micro-deformation from accumulating to macro, thereby significantly improving the high temperature resistance of the vulcanized rubber, reducing the high temperature creep of the vulcanized rubber, and realizing the synergistic optimization of the anti-creep property and the reprocessing performance of the prepared static / dynamic two-phase crosslinked rubber, and the mechanical properties of the recycled sample remain basically unchanged. At the same time, the preparation process of the present application is simple and does not require special processing equipment, and has good universality and industrial application potential. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0037] Figure 1 The preparation flow chart of the thermoplastic crosslinked rubber prepared by the embodiments of the present application. DETAILED DESCRIPTION

[0038] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0039] In the following description of the embodiments of the present application, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the cases of A existing alone, B existing alone and A and B existing simultaneously. Wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0040] In the following description of the embodiments of the present application, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following (one)" or similar expressions means any combination of these items, including any combination of single item (one) or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b and c can be single or multiple.

[0041] Those skilled in the art should understand that in the following description of the embodiments of the present application, the sequence of the serial numbers does not mean the sequence of execution, and some or all steps can be executed in parallel or in sequence, and the execution sequence of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0042] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0043] It should be noted that all raw reagents in the embodiments of the present application are purchased in the market or prepared according to the conventional method well known to those skilled in the art.

[0044] In a first aspect, the embodiments of the present application provide a preparation method of a high-temperature creep-resistant thermoplastic crosslinked rubber, the preparation method comprising:

[0045] The first rubber raw rubber and the static crosslinking agent are once mixed, once vulcanized and granulated to obtain static high-crosslinking rubber particles;

[0046] The second rubber raw rubber, a dynamic crosslinking agent, a filler and the static high crosslinking rubber particles are subjected to secondary mixing and secondary vulcanization, so as to obtain the thermoplastic crosslinked rubber with high temperature creep resistance;

[0047] The first rubber raw rubber and the second rubber raw rubber are the same or different.

[0048] The static phase in the network structure can limit excessive slippage of the dynamic phase molecular chain based on the steric hindrance effect, and the static high crosslinking rubber particles can be introduced into the dynamic crosslinking rubber as an anti-creep unit to transfer stress by means of interfacial force and prevent micro-deformation from accumulating to macro, so as to significantly improve the high temperature resistance of the vulcanized rubber, reduce the high temperature creep of the vulcanized rubber, realize the synergistic optimization of the anti-creep property and the reprocessing property of the static / dynamic two-phase crosslinked rubber, and the mechanical properties of the recycled sample are basically unchanged compared with the original sample. At the same time, the preparation process of the application is simple, does not need special processing equipment, has good universality and industrial application potential.

[0049] In the embodiment of the application, the first rubber raw rubber or the second rubber raw rubber is preferably one or more of styrene butadiene rubber, polybutadiene rubber, ethylene propylene terpolymer rubber, natural rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized natural rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer, carboxyl nitrile rubber and carboxyl styrene butadiene rubber.

[0050] In the embodiments of the present application, the static crosslinking agent refers to a crosslinking system that can crosslink the olefin rubber or the functionalized rubber to generate irreversible crosslinking bonds, and preferably is an effective sulfur vulcanization system (preferably a low-sulfur (sulfur ≤ 0.5 parts) high accelerator system, such as 0.5 parts of sulfur / 3 parts of accelerator TMTD, 0.2 parts of sulfur / 3 parts of accelerator DPTT / 0.8 parts of accelerator MZ), a peroxide crosslinking agent (preferably dicumyl peroxide DCP, di-tert-butyl peroxide DTBP, 2,5-dimethyl-2,5-bis(tert-butyl peroxide) hexane DBPH, etc.), a polythiol crosslinking agent (preferably 1,6-hexanedithiol, 1,10-decanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), 1,3,5-trimercapto-2,4,6-triazine, bis(4-mercaptophenyl) sulfide, etc.), a polyamine crosslinking agent (preferably hexamethylene diamine, diethylenetriamine, isophorone diamine, 4,4'-diaminodicyclohexyl methane, p-phenylenediamine, m-phenylenediamine, etc.), an aziridine crosslinking agent (preferably trimethylolpropane tris(3-aziridinyl) propionate, pentaerythritol tris(3-aziridinyl) propionate, trimethylolpropane tris(3-(2-methylaziridinyl) propionate), a hexafunctional aziridine crosslinking agent PX-1096, etc.), or one or more thereof.

[0051] In the embodiments of the present application, the dynamic crosslinking agent refers to a compound that can crosslink the rubber and simultaneously introduce a dynamic covalent bond, including a benzene boronic acid-containing dimercapto crosslinking agent, which refers to a mercapto compound containing a boronate bond, such as dimercapto-p-phenylenediboronic acid ester, etc., a polybasic carboxylic acid crosslinking agent, which refers to a carboxylic compound that can crosslink epoxidized rubber to generate a hydroxyl ester bond, such as sebacic acid, dimer acid, citric acid, terephthalic acid, butane tetracarboxylic acid, etc., a silicon ether bond-containing polythiol crosslinking agent, which refers to a mercapto compound containing a silicon ether bond, such as di(2-mercaptoethyl) silicate, tri(2-mercaptoethyl) silicate, tetra(2-mercaptoethyl) silicate, etc., a polybasic epoxy crosslinking agent, which refers to an epoxy compound that can crosslink carboxylated rubber to generate a hydroxyl ester bond, such as 1,6-hexane diglycidyl ether, ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, etc., or one or more thereof.

[0052] In the embodiment of the present application, when the first raw rubber and the static crosslinking agent are mixed once, vulcanized once and granulated, the mass ratio of the first raw rubber to the static crosslinking agent is preferably 100:(0.1-15), and more preferably 100:0.2; when the second raw rubber, the dynamic crosslinking agent, the filler and the static high crosslinking rubber particles are mixed twice and vulcanized twice, the mass ratio of the second raw rubber, the dynamic crosslinking agent, the filler and the static high crosslinking rubber particles is preferably 100:(0.5-10):(8-150):(10-200), and more preferably 100:2:100:100. By controlling the addition amount of each raw material, the high-temperature creep resistance of the prepared rubber can be effectively controlled.

[0053] In a second aspect, the present application also provides a high-temperature creep resistant thermoplastic crosslinked rubber prepared by the preparation method of the first aspect.

[0054] In a third aspect, the present application also provides the use of the high-temperature creep resistant thermoplastic crosslinked rubber of the second aspect in the preparation of a rubber product. The high-temperature creep resistant thermoplastic crosslinked rubber has excellent high-temperature creep resistance and excellent repeated processing performance, filling the market gap in the balance between high-temperature creep resistance and recyclable processing performance of existing materials, and providing product advantages in the market competition of high-end, green and economical rubber products.

[0055] The technical solutions of the present application will be further described below with reference to specific embodiments.

[0056] Embodiment 1

[0057] The present embodiment provides a preparation method of a high-temperature creep resistant thermoplastic crosslinked rubber. In order to verify the variable content of rubber powder and the variable type and amount of dynamic crosslinking agent, the preparation is carried out according to the process flow chart shown in Figure 1 The preparation method comprises the following steps:

[0058] S101: adding styrene-butadiene rubber and dicumyl peroxide (DCP) according to a weight ratio of 100:0.2 into an open mill for mixing at room temperature for 10 minutes; the obtained mixed rubber A1 is pressed by a flat vulcanizing machine at 160°C according to the normal vulcanization time, and is further broken to obtain static high crosslinking rubber powder (particle size of 10-800 microns), which is marked as B1;

[0059] S102: adding static high crosslinking rubber powder B1, styrene-butadiene rubber and dynamic crosslinking agent (dimercapto-p-phenylenediamine borate or di(2-mercaptoethyl)silicate) according to the amounts in Table 1 into an open mill for mixing at room temperature for 15 minutes; the obtained corresponding mixed rubber C1-C6 is added into a flat vulcanizing machine, and is pressed at 160°C according to the normal vulcanization time to obtain corresponding thermoplastic crosslinked rubber, which is marked as M1-M6;

[0060] The specific raw material usage is shown in Table 1:

[0061] Table 1. List of Raw Material Consumption for Thermoplastic Crosslinked Rubbers M1 to M6

[0062]

[0063] Example 2

[0064] This embodiment provides a method for preparing a high-temperature creep-resistant thermoplastic crosslinked rubber. To verify the type of rubber in the rubber powder, the type and amount of static crosslinking agent, and the particle size variation of the rubber powder, the following specific steps are included:

[0065] S201: Add raw rubber and static crosslinking agent to a two-roll mill according to the formula in Table 2 and mix at room temperature for 10 min; the resulting compound A2-A8 is molded at 160℃ and vulcanized for the correct time using a flat vulcanizing machine, further crushed, and sieved to obtain different types of static high crosslinked rubber powder (particle size of 10-800 micrometers), denoted as B2-B8.

[0066] S202: Take static high cross-linked rubber powder B2-B8, styrene-butadiene rubber, and dimercapto-terephthalic acid diborate according to the dosage in Table 3, add them to a two-roll mill, mix at room temperature for 15 minutes, and add the corresponding compound C7 to C11 to a flat vulcanizing machine, and mold them at 160°C for the correct vulcanization time to obtain the corresponding thermoplastic cross-linked rubber, labeled as M7-M11.

[0067] The specific raw material usage is shown in Tables 2 and 3:

[0068] Table 2. List of Raw Material Consumption for Static Highly Crosslinked Rubbers B2 to B6

[0069]

[0070] Table 3. List of Raw Material Consumption for Thermoplastic Crosslinked Rubbers M8 to M14

[0071]

[0072] Example 3

[0073] This embodiment provides a method for preparing a high-temperature creep-resistant thermoplastic crosslinked rubber. To verify the type of raw rubber, filler type and dosage, processing equipment type, and processing time in the matrix rubber, the specific methods include:

[0074] S301: Butadiene styrene rubber, static crosslinking agent DCP were added into the open mill in the weight ratio of 100:0.2 and mixed at room temperature for 10 min; the obtained mixed rubber A7 was molded by a flat vulcanizing machine at 160℃ according to the normal vulcanization time, further broken, and static high crosslinking rubber powder (particle size of 40-800 microns) was obtained, marked as B7;

[0075] S302: The static high crosslinking rubber powder B7, raw rubber, dynamic crosslinking agent, and filler were added into the open mill or internal mixer according to the amount in Table 4 and mixed for a certain time, and the obtained corresponding mixed rubber C12-C17 was added into a flat vulcanizing machine, 160℃, and molded according to the normal vulcanization time, to obtain corresponding thermoplastic crosslinking rubber, marked as M12-M17.

[0076] The specific amount of raw materials is shown in Table 4:

[0077] Table 4: Raw material usage table for thermoplastic crosslinking rubber M12-M17

[0078]

[0079] *O represents mixing using an open mill; I represents mixing using an internal mixer.

[0080] Meanwhile, to verify the comprehensive performance of the high-temperature creep-resistant thermoplastic crosslinking rubber prepared in the above examples, the following comparative examples are provided for detailed description.

[0081] Comparative Example 1

[0082] The comparative example of the present application provides a preparation method of crosslinking rubber, specifically including:

[0083] Butadiene styrene rubber and dimercapto-p-phenylenediamine borate were added into the open mill in the weight ratio of 100:2 and mixed at room temperature for 15 min, and the obtained mixed rubber DC1 was added into a flat vulcanizing machine, 160℃, and molded according to the normal vulcanization time, to obtain a comparative crosslinking rubber, marked as DM1.

[0084] Comparative Example 2

[0085] The comparative example of the present application provides a preparation method of crosslinking rubber, specifically including:

[0086] According to the formula in Table 5, raw rubber and various crosslinking agents were added into the open mill and mixed at room temperature for 15 min, and the obtained mixed rubber DC2-DC4 was added into a flat vulcanizing machine, 160℃, and molded according to the normal vulcanization time, to obtain a comparative crosslinking rubber, marked as DM2-DM4.

[0087] The specific amount of raw materials is shown in Table 5:

[0088] Table 5: Raw material usage table for comparative crosslinking rubber DM2-DM4

[0089]

[0090] Comparative Example 3

[0091] The present application comparative example provides a preparation method of crosslinked rubber, specifically comprising:

[0092] The butadiene styrene rubber, static crosslinking agent DCP, dimercapto crosslinking agent containing phenylboronic acid, and carbon black were added into a mixer in a weight ratio of 100:0.25:1:40, and mixed at 40°C for 10 min. The obtained mixed rubber DC5 was added into a flat vulcanizing machine, and molded at 160°C according to the normal vulcanization time to obtain a comparative crosslinked rubber, marked as DM5.

[0093] Comparative Example 4

[0094] The present application comparative example provides a preparation method of crosslinked rubber, specifically comprising:

[0095] The butadiene styrene rubber, carboxyl butadiene styrene rubber, static crosslinking agent DCP, 1,6-hexane glycidyl ether, and graphene were mixed by an open mill at room temperature for 20 min in a weight ratio of 50:50:0.25:2:4. The obtained mixed rubber DC6 was added into a flat vulcanizing machine, and molded at 160°C according to the normal vulcanization time to obtain a comparative crosslinked rubber, marked as DM6.

[0096] The mechanical properties of the high-temperature creep resistant thermoplastic crosslinked rubber prepared in the above examples were tested:

[0097] Recovery method: the thermoplastic crosslinked rubbers M1-M17 and the comparative crosslinked rubbers DM1-DM6 were taken respectively, and after application experiments such as tensile, tear, wear resistance, and fatigue resistance, the used interface crosslinked rubbers M1*-M17* and the used comparative crosslinked rubbers DM1*-DM6* were obtained. The used thermoplastic crosslinked rubbers M1*-M17* and the used comparative crosslinked rubbers DM1*-DM6* were taken respectively, and the obtained corresponding fragments were molded at 160°C for 5 min to obtain the corresponding recovered crosslinked rubbers N1-N17 and the recovered comparative crosslinked rubbers DN1-DN6.

[0098] Performance test: the thermoplastic crosslinked rubbers M1-M17, the comparative crosslinked rubbers DM1-DM6, the recovered thermoplastic crosslinked rubbers N1-N17, and the recovered comparative crosslinked rubbers DN1-DN6 were tested respectively, and the specific test method was as follows:

[0099] Tensile strength test: the test was carried out on a U-CAN UT-2060 tensile machine, the test standard was ISO 37-2005, the test temperature was room temperature, and the tensile rate was 500 mm / min. At least 5 parallel tests were carried out, and the average value was taken.

[0100] Elongation at break: The test was performed on a U-CAN UT-2060 tensile machine, the test standard was ISO 37-2005, the test temperature was room temperature, and the tensile rate was 500 mm / min. At least 5 parallel tests were performed, and the average value was taken.

[0101] Gel content test: The gel content was measured by equilibrium swelling experiment. The specific experimental steps were as follows: the rubber sheet with a mass of m0 was soaked in toluene, the solvent was replaced every 24 h, after soaking for 72 h, the swelling equilibrium was reached, the sample was taken out and placed in a vacuum oven at 60°C to dry to a constant weight, the mass was m1, each sample was tested three times. The gel content (GF) was calculated according to equation (1-1): GF = m1 / m0 x 100%;

[0102] Creep experiment: performed on TADMA Q800. Set the constant constant stress to 0.2 MPa, measure the change of sample creep amount with time at the corresponding temperature, before the experiment, the sample was kept at the test temperature for 10 min.

[0103] The tensile strength recovery rate, 100% modulus recovery rate and elongation at break recovery rate of the thermoplastic crosslinked rubber N1-N17 and the comparative crosslinked rubber DN1-DN6 after reprocessing and recycling were calculated, and the calculation formula was as follows:

[0104] Tensile strength recovery rate = tensile strength of recycled crosslinked rubber ÷ tensile strength of unused crosslinked rubber x 100%;

[0105] Elongation at break recovery rate = elongation at break of recycled crosslinked rubber ÷ elongation at break of unused crosslinked rubber x 100%;

[0106] The test results are shown in Table 6:

[0107] Table 6 Performance test results of thermoplastic crosslinked rubber M1-M6 and comparative crosslinked rubber DM1

[0108] Crosslinked rubber marker code ~ n M1 M2 M3 M4 M5 M6 DM1 Gel content GF (%) 88.7 92.6 96.3 74.2 97.4 92.2 85.4 Tensile strength (MPa) 4.2 5.8 6.7 4.1 6.3 6.1 3.7 Elongation at break (%) 325 178 141 416 103 198 265 Creep rate (% / min, 160°C) 0.1720 0.1009 0.0532 0.1312 0.0832 0.0901 0.1846 Repeated processing recovery (Yes / No) Y Y Y Y Y Y Y Tensile strength recovery rate (%) 94 102 99 95 94 97 90 Elongation at break recovery rate (%) 93 104 97 97 91 94 87

[0109] From the comparative sample DM1, it can be seen that DM1 is a homogeneous crosslinked rubber sample prepared from a single dynamic crosslinking agent, and its formulation is consistent with the dynamic crosslinking phase of the static / dynamic crosslinked two-phase rubber M1-M3. As can be seen from Table 6, compared with the comparative crosslinked rubber DM1, with the introduction of the static high crosslinking particle phase, the gel content of the static / dynamic crosslinked two-phase rubber M1-M3 is significantly improved, and has higher tensile strength than the comparative sample DM1. More importantly, M1-M3 has a high temperature creep rate significantly better than DM1, and the creep rate gradually decreases with the increase of the content of the static high crosslinking particle phase. Notably, the introduction of the static high crosslinking particle phase does not cause the dynamic crosslinking network to deteriorate in reprocessing performance. On the contrary, M1-M3 has better repeated processing capability than DM1, and under the same reprocessing conditions, has higher retention rate of tensile strength and elongation at break. The above experiments show that by introducing the static high crosslinking particle phase, the dynamic crosslinking matrix rubber network can be enhanced, and at the same time the prepared two-phase crosslinked rubber has excellent high temperature creep resistance and reprocessing performance.

[0110] As can be seen from the results of comparative M2, M4 and M5, with the increase of the amount of dynamic crosslinking agent, the gel content of the two-phase crosslinked rubber is improved, which is due to the contribution of higher crosslinking density of the matrix phase and additional interfacial crosslinking. And with the increase of the amount of dynamic crosslinking agent, the creep rate of the two-phase crosslinked rubber is reduced, which is because the higher crosslinking density restricts the topological rearrangement of the network. In addition, the content of the dynamic crosslinking agent also has a certain influence on the reprocessing performance of the two-phase crosslinked rubber, and obviously the appropriate amount of dynamic crosslinking agent can adjust the high temperature creep resistance and repeated processing performance of the two-phase crosslinked rubber to obtain the best combination.

[0111] The results of M2 and M6 in Table 6 also show that the type of dynamic crosslinking agent also has a direct influence on the creep resistance and reprocessing performance of the two-phase crosslinked rubber. Since the siloxane dynamic bond in M6 has a higher exchange activation energy, it exhibits a lower creep rate, and relatively, since the borate ester bond in M2 has a low exchange activation energy, it has better reprocessing performance (higher mechanical property retention rate). The above experiments show that by introducing the static high crosslinking rubber particles as "anti-creep units" in the dynamic crosslinked rubber, the static / dynamic two-phase crosslinked rubber prepared has excellent creep resistance, while maintaining excellent reprocessing performance, and the mechanical properties of the recycled sample are basically maintained. The examples of the present application show that the content of different static high crosslinking particle phases, the amount and type of dynamic crosslinking agent all have a direct influence on the creep performance and reprocessing performance of the two-phase crosslinked rubber, and by adjusting these influencing factors, the dimensional stability (creep resistance) and recycling performance of the two-phase crosslinked rubber can be effectively adjusted.

[0112] The tensile strength recovery rate and elongation at break recovery rate of the recycled thermoplastic crosslinked rubber N7-N11 and the recycled comparative crosslinked rubber DN2-DN4 were calculated, and the specific test results are shown in Table 7:

[0113] Table 7 Performance test results of thermoplastic crosslinked rubber M8-M12 and comparative crosslinked rubber DM2-DM4

[0114]

[0115] According to Table 7, the optimal amount of each substance is screened according to the above examples, and it is found that the high-temperature creep resistance is obviously lower than that of the step-by-step sequential addition in the examples, and it does not have the repeatable processing performance, compared with the one-step mixing of Comparative Example 3.

[0116] The tensile strength recovery rate and elongation at break recovery rate of the recycled thermoplastic crosslinked rubber N12-N17 and the recycled comparative crosslinked rubber DN5-DN6 are calculated, and the specific test results are shown in Table 8:

[0117] Table 8 Performance test results of thermoplastic crosslinked rubber M12-M17 and comparative crosslinked rubber DM5-DM6

[0118]

[0119]

[0120] According to Table 8, the optimal amount of each substance is screened according to the above examples, and it is found that the high-temperature creep resistance is obviously lower than that of the step-by-step sequential addition in the examples, and it does not have the repeatable processing performance, compared with the one-step mixing of Comparative Example 3.

[0121] Therefore, by introducing static high-crosslinking rubber particles into dynamically covalently crosslinked rubber, a static / dynamic crosslinked anti-creep two-phase network structure is formed, which endows the rubber with excellent high-temperature creep resistance and excellent repeatable processing performance. Therefore, the present application proposes a method for preparing crosslinked rubber with high-temperature creep resistance and repeatable processing performance, and a large class of rubber compositions with excellent dimensional stability (creep resistance) and repeatable processing performance.

[0122] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be mutually referred to, and each embodiment focuses on the differences from other embodiments.

[0123] The above examples are only used to illustrate the technical solutions of the present application, and are not limited to the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions described in the foregoing examples can be modified, or some or all of the technical features can be replaced by equivalents; 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 present application.

Claims

1. A method for preparing a high temperature creep resistant thermoplastic crosslinked rubber, characterized in that, The preparation method comprises: The first rubber raw rubber and the static crosslinking agent are once mixed, once vulcanized, and granulated to obtain static high crosslinking rubber particles; The second rubber raw rubber, the dynamic crosslinking agent, the filler and the static high crosslinking rubber particles are twice mixed and twice vulcanized to obtain the high-temperature creep resistant thermoplastic crosslinking rubber. The first rubber raw rubber and the second rubber raw rubber are the same or different.

2. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The first rubber raw rubber is one or more of styrene butadiene rubber, polybutadiene rubber, ethylene propylene diene rubber, natural rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized natural rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer, carboxyl nitrile rubber and carboxyl styrene butadiene rubber. The second rubber raw rubber is one or more of styrene butadiene rubber, polybutadiene rubber, ethylene propylene diene rubber, natural rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized natural rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, epoxidized styrene / isoprene block copolymer, carboxyl nitrile rubber and carboxyl styrene butadiene rubber.

3. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The static crosslinking agent is one or more of effective sulfur vulcanization system, peroxide crosslinking agent, polythiol crosslinking agent, polyamine crosslinking agent and aziridine crosslinking agent. The peroxide crosslinking agent is one or more of dicumyl peroxide, di-tert-butyl peroxide and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The polythiol crosslinking agent is one or more of 1,6-hexanedithiol, 1,10-decanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), 1,3,5-trimercapto-2,4,6-triazine and bis(4-mercaptophenyl) sulfide. The polyamine crosslinking agent is one or more of hexamethylene diamine, diethylenetriamine, isophorone diamine, 4,4'-diaminodicyclohexylmethane, p-phenylenediamine and m-phenylenediamine. The aziridine crosslinking agent is one or more of trimethylolpropane tris(3-aziridinyl) propionate, pentaerythritol tris(3-aziridinyl) propionate and trimethylolpropane tris(3-(2-methylaziridinyl) propionate).

4. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The dynamic crosslinking agent is one or more of benzene boronic acid-containing dimercapto crosslinking agent, polybasic carboxylic acid crosslinking agent, silicon ether bond-containing dimercapto crosslinking agent and polybasic epoxy crosslinking agent. The benzene boronic acid-containing dimercapto crosslinking agent is dimercapto-p-phenylenediboronic acid ester. The polybasic carboxylic acid crosslinking agent is one or more of sebacic acid, dimer acid, citric acid, terephthalic acid and butane tetracarboxylic acid. The silicon ether bond-containing dimercapto crosslinking agent is one or more of di(2-mercaptoethyl) silicate, tri(2-mercaptoethyl) silicate and tetra(2-mercaptoethyl) silicate. The multi-element epoxy crosslinking agent is one or more of 1,6-hexane diglycidyl ether, ethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

5. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The filler includes one or more of carbon black, carbon nanotubes, graphene, graphene oxide, white carbon black, calcium carbonate, and coal ash powder.

6. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The first mixing is closed mixing or open mixing. If closed mixing is used, the mixing temperature is 30-50 DEG C, the mixing time is 8-15 min, the crosslinking temperature is 140-180 DEG C, and the time is the positive curing time. If open mixing is used, the mixing temperature is room temperature, and the mixing time is 5-20 min.

7. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The second mixing is closed mixing or open mixing. If closed mixing is used, the mixing temperature is 30-50 DEG C, the mixing time is 8-15 min, the crosslinking temperature is 140-180 DEG C, and the time is the positive curing time. If open mixing is used, the mixing temperature is room temperature, and the mixing time is 5-20 min.

8. The method for preparing the high-temperature creep-resistant thermoplastic crosslinked rubber according to claim 1, characterized in that, The mass ratio of the first rubber raw rubber and the static crosslinking agent is 100:(0.1-15) during the first mixing, the first vulcanization, and the granulation of the first rubber raw rubber and the static crosslinking agent. The mass ratio of the second rubber raw rubber, the dynamic crosslinking agent, the filler, and the static high crosslinking rubber particles is 100:(0.5-10):(8-150):(10-200) during the second mixing and the second vulcanization of the second rubber raw rubber, the dynamic crosslinking agent, the filler, and the static high crosslinking rubber particles. 9.A high-temperature creep resistant thermoplastic crosslinked rubber prepared by the method of any one of claims 1-8. 10.Use of the high-temperature creep resistant thermoplastic crosslinked rubber of claim 9 in the preparation of rubber products.

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