Preparation method of soft vulcanizing agent film

Abstract

The invention provides a preparation method of a soft vulcanizing agent rubber sheet, and relates to the technical field of vulcanizing agent rubber sheet preparation, and the preparation method comprises the following steps: putting 15-25 parts by weight of CM3510, 50-60 parts by weight of a vulcanizing agent, 15-20 parts by weight of dioctyl phthalate, 1-2 parts by weight of an active agent and 1-2 parts by weight of a lubricant into an internal mixer, mixing at a rotating speed of 35-40 revolutions per minute until the temperature reaches 100 + / -5 DEG C, and discharging; transferring the discharged material to a first open mill, and carrying out primary milling for 1 minute at a rotating speed of 25-30 m / min to form a fragment-shaped rubber material; transferring the fragmented rubber material to a second open mill, and refining for 1-2 minutes at the rotating speed of 18-20 m / min until the temperature is reduced to 70 + / -2 DEG C to obtain a refined rubber sheet; and placing the refined rubber sheet in a cooling device, cooling to 40 DEG C at a speed of 10-15 DEG C / min, and then naturally cooling to 25 DEG C or below for storage. According to the preparation method, the hardness defect and the dispersity defect of a traditional vulcanizing agent film are overcome by coupling technologies of a low Mooney skeleton, a high-efficiency plasticizer, double-stage open milling and gradient cooling.

Description

Technical Field

[0001] The present application relates to the technical field of vulcanizing agent film preparation, and in particular to a method for preparing a soft vulcanizing agent film. Background Art

[0002] In the production of rubber vulcanizer films, the traditional method uses nitrile rubber or CPE135A as the backbone material, combined with chlorinated paraffin oil as a plasticizer, and the films are prepared using internal and open mixers. This technology has two major drawbacks: hardness: the nitrile rubber / CPE135A molecular chains are highly rigid (Mooney viscosity ML(1+4) ≥ 70 at 100°C); and chlorinated paraffin oil has a low plasticizing efficiency (plasticizing factor ≤ 0.3), resulting in a high Shore A hardness of the films. Furthermore, dispersibility: the hard films are difficult to break up during secondary mixing, forming undispersed clumps with a particle size greater than 100μm. This leads to uneven local crosslinking in the rubber products (large fluctuations in tensile strength). Summary of the Invention

[0003] In view of the above-mentioned defects or deficiencies in the prior art, the present application aims to provide a method for preparing a soft vulcanizing agent film, comprising the following steps: Put 15-25 parts by weight of CM3510, 50-60 parts by weight of vulcanizing agent, 15-20 parts by weight of dioctyl ester, 1-2 parts by weight of active agent, and 1-2 parts by weight of lubricant into an internal mixer, mix at 35-40 rpm until the temperature reaches 100±5°C, and then discharge; Transfer the discharge material to the first open mill and mix it at a speed of 25-30 m / min for 1 minute to form a crumb rubber compound; Transfer the shredded rubber material to a second open mill and refine it at a speed of 18-20 m / min for 1-2 minutes until the temperature drops to 70±2°C to obtain refined rubber sheets; The refined film is placed in a cooling device, first cooled to 40° C. at a rate of 10-15° C. / min, and then naturally cooled to below 25° C. for storage.

[0004] According to the technical solution provided in this application, the vulcanizing agent is added in stages: First, add 50% of the vulcanizing agent and mix with CM3510 and dioctyl ester for 3 minutes; The remaining vulcanizing agent, activating agent and lubricant are added when the temperature is ≥80℃.

[0005] According to the technical solution provided in this application, during the refining process of the second open mill, an isolation agent prepared by mixing silicone oil and anhydrous ethanol in a ratio of 1:5 is sprayed onto the surface of the rubber material, and the spraying amount is 0.1-0.3% of the weight of the flaky rubber material.

[0006] According to the technical solution provided in this application, the cooling device is an inert gas protection cabin with a gas dew point of ≤-40°C and an oxygen concentration of ≤100ppm.

[0007] According to the technical solution provided in this application, the vulcanizing agent includes sulfur, accelerator TMTD and unsaturated fatty acid zinc salt, and the mass ratio of the three is (40~45): (8~10): (2~3).

[0008] According to the technical solution provided in this application, before being put into the internal mixer, dioctyl ester and CM3510 are premixed at 60±5°C for 10-15 minutes to form a pre-swelling rubber material, and the premixing stirring speed is 200-300 rpm.

[0009] According to the technical solution provided in this application, the first open mill adopts a spiral groove roller with a groove depth of 0.5~1mm and a pitch angle of 30°~45°. When the rubber material passes through the roller gap, it is subjected to a shear rate of ≥500s -1 .

[0010] According to the technical solution provided in this application, a hydraulic pressure platform is provided in the inert gas protection cabin. After cooling to 40°C at a rate of 10-15°C / min, the following steps are further included: Applying a vertical pressure of 0.5-1 MPa to the film through the hydraulic platform for 2-3 minutes, and maintaining the oxygen concentration in the inert gas protection chamber ≤ 100 ppm during the pressurization process; The natural cooling to below 25° C. for storage comprises the following steps: After the pressure holding is completed, cool naturally to below 25℃ for storage.

[0011] According to the technical solution provided in this application, the lubricant is a compound of oxidized polyethylene wax and calcium stearate, the mass ratio of the two is 1:1, and the melting point of the compound is 115~125℃.

[0012] According to the technical solution provided in this application, the active agent is a composite system of nano zinc oxide and an organic zinc complex, wherein: Nano zinc oxide particle size is 20~50nm, specific surface area is 30~50m² / g; The organic zinc complex is a mixture of zinc ethylenediaminetetraacetate and zinc dimercaptobenzothiazole in a mass ratio of 1:(0.3~0.5); The mass ratio of nano zinc oxide to organic zinc complex in the composite system is (0.6-0.8):1.

[0013] Compared with existing technologies, this application offers the following advantages: CM3510 with a low Mooney viscosity (ML(1+4) ≤ 50 at 125°C) is used to reduce molecular chain entanglement; dioctyl ester molecules penetrate the rubber network (increasing free volume), lowering the glass transition temperature (Tg) by 8-10°C and significantly reducing hardness. Furthermore, a two-stage open mill process is employed: the first open mill refines the rubber into 1-5 mm fragments, increasing the specific surface area; the second open mill refines the rubber, applying gentle shear to prevent secondary agglomeration, improving dispersion efficiency, and enhancing uniformity. Gradient cooling at 10-15°C / minute inhibits molecular chain rearrangement and eliminates microcracks caused by internal stress. Thus, this application utilizes a "low Mooney structure + high-efficiency plasticizer, two-stage open mill, and gradient cooling" technology: CM3510 + dioctyl ester builds a flexible network, while rough refining fragments the rubber, followed by refining and shaping in a non-equilibrium process. Rapid freezing freezes the disordered molecular chains, preventing crystallization and hardening, thereby addressing the hardness and dispersibility shortcomings of films made with conventional vulcanizers. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a flow chart of the steps of the method for preparing the soft vulcanizing agent film provided in this application. DETAILED DESCRIPTION

[0015] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0016] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0017] Example 1 As mentioned in the background technology, in order to solve the problems in the prior art, the present application proposes a method for preparing a soft vulcanizing agent film, comprising the following steps: S1. Add 15-25 parts by weight of CM3510, 50-60 parts by weight of vulcanizing agent, 15-20 parts by weight of dioctyl ester, 1-2 parts by weight of active agent, and 1-2 parts by weight of lubricant into an internal mixer, mix at 35-40 rpm until the temperature reaches 100±5°C, and then discharge; S2, transfer the discharge material to the first open mill, and roughly refine it at a speed of 25-30 m / min for 1 minute to form a fragmented rubber material; S3, transferring the rubber fragments to a second open mill, and refining the rubber fragments at a speed of 18-20 m / min for 1-2 minutes until the temperature drops to 70±2° C., to obtain refined rubber sheets; S4. Place the refined rubber sheet in a cooling device and first cool it to 40°C at a rate of 10-15°C / min, then naturally cool it to below 25°C for storage. A cooling rate of 10-15°C / min corresponds to the critical rate of relaxation of the rubber molecular chain (DSC verification). Internal stress concentration occurs when the cooling rate is greater than 15°C / min.

[0018] The reaction mechanism is explained below: Low Mooney CM3510 + dioctyl ester builds a flexible network, and the Mooney viscosity of CM3510 is less than or equal to 50: the molecular chain is short and the entanglement density is low, providing an initial flexible skeleton. Dioctyl ester small molecule penetration: the plasticizer is inserted between the rubber molecular chains, increasing the free volume, reducing the resistance to chain segment movement, and reducing the glass transition temperature (Tg) by 8~10℃, significantly softening the rubber compound (reducing hardness). Two-stage milling process: First milling (high shear): high speed (25~30 m / min) and shear rate (≥500s -1 ) Tearing the rubber into 1-5 mm fragments increases the specific surface area and breaks up initial agglomerates. Second open mill refining (gentle shear): Low speed (18-20 m / min) controls the temperature rise (≤70°C) to prevent high temperatures from causing pre-crosslinking of the vulcanizer or molecular chain entanglement (secondary agglomeration), maintaining a fragmented and dispersed state. Gradient cooling freezes the non-equilibrium state: Rapid cooling stage (10-15°C / min): Rapidly passes through the molecular chain rearrangement temperature range (Tg-Tm), inhibiting ordered arrangement (crystallization) and freezing the disordered structure. Natural cooling stage: Avoids internal stress concentration caused by sudden cooling and eliminates the risk of microcracks. Technical coupling effect: "Flexible skeleton + fragmented dispersion + amorphous freezing" synergistically: Low Mooney CM3510 and dioctyl ester form a high-free volume network, which reduces hardness; crude refining fragmentation improves the dispersion interface, which resolves uneven dispersion; refining low-temperature setting and rapid freezing freezes, which inhibits crystallization and hardening.

[0019] The following is the verification of the CM3510 dosage boundary (other components are fixed), and the verification data is shown in Table 1: Table 1

[0020] As shown in the table above, if CM3510 < 15 phr: insufficient skeleton material → strength decreases by 18% (compared to 20 phr). If CM3510 > 25 phr: Mooney viscosity rises to 65, and hardness exceeds the target value (≥75 Shore A).

[0021] The following is the verification of the vulcanizing agent dosage boundary (fixing other components), and the verification data is shown in Table 2: Table 2

[0022] As can be seen from the above table, if the weight proportion of the vulcanizing agent is less than 50 parts, the cross-linking density is insufficient, resulting in an increase in the permanent deformation rate (>25% exceeds the standard); if the weight proportion of the vulcanizing agent is greater than 60 parts, the excessive vulcanizing agent agglomerates, resulting in a 386% increase in the proportion of aggregates (verified by SEM).

[0023] The following is a verification of the dioctyl ester dosage limit (glass transition temperature Tg is related to hardness), and the verification data is shown in Table 3: Table 3

[0024] As can be seen from the above table, if the weight proportion of dioctyl ester is less than 15 parts, plasticization is insufficient, resulting in a Tg decrease of less than 8°C and a hardness of ≥64 Shore A; if the weight proportion of dioctyl ester is greater than 20 parts, the risk of precipitation increases (migration rate > 0.2%), resulting in a decrease in long-term storage stability.

[0025] The following is a verification of the synergistic effect of key parameters. The data is shown in Table 4, where the comprehensive score = 0.4 × dispersion + 0.3 × (100-hardness range) + 0.3 × strength retention rate: Table 4

[0026] As can be seen from the table above, only when the three conditions of CM3510 (15-25), curing agent (50-60), and dioctyl ester (15-20) are met simultaneously can the following be achieved: dispersion > 95%, eliminating agglomeration defects (a 14% improvement compared to traditional solutions); hardness range < 2 Shore A, eliminating distribution defects; no migration or precipitation, and qualified storage stability.

[0027] In a preferred embodiment, the vulcanizing agent is added in stages: First, add 50% of the vulcanizing agent and mix with CM3510 and dioctyl ester for 3 minutes; The remaining vulcanizing agent, activating agent and lubricant are added when the temperature is ≥80℃.

[0028] Specifically, the vulcanizing agent is added in stages: The first stage (50% vulcanizing agent + CM3510 / dioctyl ester) involves low-temperature mixing (≤80°C) to prevent premature activation of the vulcanizing agent. The sulfur particles are then encapsulated with a plasticizer (dioctyl ester) and pre-dispersed into the rubber continuous phase. The second stage (remaining vulcanizing agent + activator / lubricant) involves adding an accelerator (such as TMTD) and activator at a higher temperature (≥80°C) to precisely trigger vulcanization activity and avoid scorching. Lubricants are also added simultaneously to reduce frictional heat and maintain dispersion stability.

[0029] This embodiment matches temperature and reaction activity in stages to improve the uniformity of vulcanizing agent dispersion and prevent local cross-linking (hardness fluctuation).

[0030] In a preferred embodiment, during the refining process of the second open mill, a release agent prepared by mixing silicone oil and anhydrous ethanol at a ratio of 1:5 is sprayed onto the surface of the rubber compound, with the spraying amount being 0.1-0.3% of the weight of the flaked rubber compound.

[0031] Specifically, a silicone oil / ethanol (1:5) blend system: ethanol evaporates quickly, removing heat and aiding cooling; the silicone oil forms a molecular-level barrier, reducing the rubber's surface energy. A spray rate of 0.1-0.3% allows for precise control of film thickness (nanometer-level), preventing both adhesion and excess release agent from penetrating the colloid and impacting vulcanization.

[0032] This embodiment can maintain the surface integrity of the refined film and ensure that there is no structural damage in the subsequent cooling process.

[0033] In a preferred embodiment, the cooling device is an inert gas protection cabin with a gas dew point of ≤-40°C and an oxygen concentration of ≤100 ppm.

[0034] Specifically, the dew point is ≤-40°C and the oxygen level is ≤100ppm, which can eliminate local hardening caused by water condensation (water molecules react with active agents such as ZnO); isolating oxygen prevents oxidation failure of the vulcanizing agent (such as sulfur → SO2) and oxidation and cracking of the rubber surface.

[0035] This embodiment ensures the chemical stability of the film during the cooling process and avoids performance degradation.

[0036] In a preferred embodiment, the vulcanizing agent includes sulfur, accelerator TMTD and unsaturated fatty acid zinc salt, and the mass ratio of the three is (40-45): (8-10): (2-3).

[0037] Specifically, sulfur acts as the main cross-linking agent, providing flexible sulfur bonds (-Sx-); TMTD acts as an ultra-fast accelerator, lowering the vulcanization temperature and compensating for the activation delay caused by low-temperature mixing; unsaturated fatty acid zinc salt has both activator and plasticizer functions, and its long alkyl chain intersperses the network, further increasing the free volume.

[0038] This embodiment synergistically reduces the cross-linking density and improves the softness of the film.

[0039] In a preferred embodiment, before being put into the internal mixer, dioctyl ester and CM3510 are premixed at 60±5° C. for 10-15 minutes to form a pre-swelling rubber material, and the premixing stirring speed is 200-300 rpm.

[0040] Specifically, premixing at 60±5°C—well below the boiling point of dioctyl ester (>300°C) and the decomposition temperature of CM3510—selectively softens the rubber phase. Medium-speed stirring (200-300 rpm) creates a "pre-swelling compound": plasticizer molecules are pre-embedded in the rubber network, shortening mixing time by 20% and avoiding local concentration gradients. This ensures uniform plasticization from the source and prevents uneven hardness distribution.

[0041] In a preferred embodiment, the first mixing mill uses a spiral grooved roller with a groove depth of 0.5-1 mm and a pitch angle of 30°-45°. When the rubber material passes through the roller gap, the shear rate is ≥500s-1.

[0042] Specifically, the groove depth is 0.5~1mm + the pitch angle is 30°~45°: the grooves produce axial diversion and enhance shear (shear rate ≥ 500s -1 The pitch angle optimizes rubber material conveying efficiency and prevents scorching. The size of crude refining fragments is controllable (1-5mm), increasing the specific surface area and laying the foundation for refined dispersion.

[0043] In a preferred embodiment, a hydraulic pressure platform is provided in the inert gas protection cabin, and after cooling to 40°C at a rate of 10-15°C / min, the following steps are further included: Applying a vertical pressure of 0.5-1 MPa to the film through the hydraulic platform for 2-3 minutes, and maintaining the oxygen concentration in the inert gas protection chamber ≤ 100 ppm during the pressurization process; The natural cooling to below 25° C. for storage comprises the following steps: After the pressure holding is completed, cool naturally to below 25℃ for storage.

[0044] Specifically, a vertical pressure of 0.5-1 MPa is maintained for 2-3 minutes. This pressure forces the molecular chains to relax in a directional manner above Tg (40°C), eliminating internal voids. Pressurization under an inert gas atmosphere simultaneously inhibits oxidation and void collapse. This eliminates cooling shrinkage stress, increases film density by 8-10%, and completely prevents microcracks.

[0045] In a preferred embodiment, the lubricant is a compound of oxidized polyethylene wax and calcium stearate, with a mass ratio of 1:1 and a melting point of 115-125°C.

[0046] Specifically, the oxidized polyethylene wax + calcium stearate (1:1 ratio) combines: oxidized polyethylene wax (melting point 115-125°C) melts at high temperatures to lubricate the mixer cavity, reducing mechanical energy consumption; calcium stearate migrates to the rubber surface, reducing friction on the mixer rollers. This dual lubrication mechanism reduces mixing temperature rise by 5-8°C, preventing high-temperature-induced pre-vulcanization (increased hardness). The compound's melting point of 115-125°C matches the mixer discharge temperature (100±5°C), achieving melt lubrication.

[0047] In a preferred embodiment, the active agent is a composite system of nano zinc oxide and an organic zinc complex, wherein: Nano zinc oxide particle size is 20~50nm, specific surface area is 30~50m² / g; The organic zinc complex is a mixture of zinc ethylenediaminetetraacetate and zinc dimercaptobenzothiazole in a mass ratio of 1:(0.3~0.5); The mass ratio of nano zinc oxide to organic zinc complex in the composite system is (0.6-0.8):1.

[0048] Specifically, nano zinc oxide (20~50nm): high specific surface area (30~50m 2 / g) provides more Zn 2+ Activates sites, promoting sulfide ring cleavage. Organic zinc complex (EDTA zinc + MBT zinc): EDTA zinc: Strong complexing ability stabilizes the zinc ion release rate; MBT zinc: Provides both activating and antioxidant properties. Mixing ratio (0.6-0.8): 1: Nano-ZnO provides primary activation, while organic zinc maintains crosslinking over time, preventing reversion. This achieves efficient and uniform vulcanization at low dosages, ensuring a balance between film softness and durability. The combined system uses nano-ZnO to provide instantaneous activation sites, while the organic zinc complex controls ion release. A mass ratio of <0.6 results in a vulcanization delay of >50%.

[0049] Example 2 (Basic Process) Based on Example 1, this example provides a basic process: Raw material ratio: CM3510: 20 parts by weight Vulcanizing agent: 55 parts by weight (42 parts sulfur + 9 parts TMTD + 4 parts unsaturated fatty acid zinc salt) Dioctyl ester: 18 parts by weight Active agent: 1.5 parts by weight (0.9 parts of nano zinc oxide + 0.6 parts of zinc EDTA / zinc dimercaptobenzothiazole = 1:0.4) Lubricant: 1.5 parts by weight (oxidized polyethylene wax / calcium stearate = 1:1) step: Premix swelling: Premix dioctyl ester and CM3510 at 60°C and 250 rpm for 12 minutes.

[0050] Staged refining: First, add premixed rubber + 50% vulcanizing agent (27.5 parts) at a mixer speed of 38 rpm; When the temperature reaches 80°C, add the remaining vulcanizing agent (27.5 parts) + activator + lubricant, mix until the temperature reaches 102°C and discharge (total time 8 minutes).

[0051] Rough refining: First open mill (spiral groove roller, groove depth 0.8mm, pitch angle 40°), speed 28m / min, shear rate 550s -1 , and roughly refine for 1 minute to obtain the rubber fragments.

[0052] Refining: The second open mill rotates at 19 m / min, sprays a release agent (silicone oil: anhydrous ethanol = 1:5, dosage 0.2%), and refines for 1.5 minutes to 69°C.

[0053] Cooling: Inert gas protection chamber (N2 dew point -45℃, O2≤80ppm), cool to 40℃ at 12℃ / min → hydraulic pressurize to 0.8MPa and maintain pressure for 2.5 minutes → naturally cool to 23℃ for storage.

[0054] Example 3 (stage-by-stage feeding verification) The same as Example 1, but all the vulcanizing agent is added at one time.

[0055] Example 4 (Verification of Release Agent Dosage) Same as Example 1, but no release agent was sprayed during refining.

[0056] Example 5 (Cooling Rate Verification) The same as Example 1, but the cooling rate is changed to 18°C / min (breaking through the 10-15°C / min of Claim 4).

[0057] Example 6 (Verification of Vulcanizing Agent Ratio) Adjust the vulcanizing agent ratio: sulfur: TMTD: zinc salt = 38:12:5 (exceeding the scope of claim 5).

[0058] Example 7 (Pressure Cooling Verification) Same as Example 1, but the hydraulic pressurization step is eliminated.

[0059] Performance testing methods and results Test items: Mooney scorch time (MS t5, 130°C): GB / T 1233; Dispersion: ISO 11345 (laser disperser, the higher the value, the more uniform); Film adhesion: GB / T 3510 (peel force after storage at 25°C for 7 days, N / cm); Mechanical properties of vulcanized rubber: GB / T 528 (tested after adding 5% of the rubber to the NR rubber compound and vulcanizing); Film hardness uniformity (GB / T 531.1): Measure the Shore A hardness at 5 points on the film and calculate the range (reflecting hardness distribution defects); Fluctuation of Mooney viscosity of rubber mix (GB / T 1232.1): Prepare three rubber mixes from the same batch of film and measure the standard deviation of the Mooney viscosity; SEM analysis of curing agent dispersion (ISO 11345): SEM observation of the number of curing agent aggregates (the proportion of particles ≤2μm); The test data is shown in Table 1: Table 5

[0060] As can be seen from the above table, the proportion of aggregates in Example 2 is only 4.3%, while the proportion of aggregates in Examples 3 and 5 is as high as 12.7% and 18.2%, respectively. This proves that the staged feeding and the ratio of the vulcanizing agent (the vulcanizing agent includes sulfur, accelerator TMTD and unsaturated fatty acid zinc salt, and the mass ratio of the three is (40~45): (8~10): (2~3)) significantly reduce agglomeration; in addition, the standard deviation of the Mooney viscosity fluctuation of Example 2 is 0.15, and that of Example 3 is 0.41, reflecting that the dispersion uniformity of the vulcanizing agent is improved and the quality of the compounded rubber is stable. In addition, it can be seen from the above table that the hardness defects are improved: the extreme hardness difference: Example 2 is only 1.2 Shore A, and Example 6 reaches 4.5 Shore A, because hydraulic pressure eliminates the cooling stress concentration, and the lubricant compounding improves the leveling property. Electron microscopy correlation: the proportion of aggregates is positively correlated with the extreme hardness difference (R 2 =0.92), confirming that uneven dispersion directly leads to hardness distribution defects, further supporting the fact that the present application improves dispersion uniformity to improve uneven hardness distribution defects, thereby achieving a soft film. Comprehensive performance verification: Dispersion → Processability: When the dispersion is greater than 95%, the Mooney scorch time is extended by 21% (comparing Examples 2 and 3), ensuring processing safety. Hardness uniformity → Finished product performance: When the hardness difference is ≤2 Shore A, the vulcanized rubber tensile strength is greater than 25 MPa (Comparing Examples 2 and 5 with Examples 4 and 6).

[0061] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of the present invention, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for preparing a soft vulcanizing agent film, characterized in that: The following steps are involved: Put 15-25 parts by weight of CM3510, 50-60 parts by weight of vulcanizing agent, 15-20 parts by weight of dioctyl ester, 1-2 parts by weight of active agent, and 1-2 parts by weight of lubricant into an internal mixer, mix at 35-40 rpm until the temperature reaches 100±5°C, and then discharge; Transfer the discharge material to the first open mill and mix it at a speed of 25-30 m / min for 1 minute to form a crumb rubber compound; Transfer the shredded rubber material to a second open mill and refine it at a speed of 18-20 m / min for 1-2 minutes until the temperature drops to 70±2°C to obtain refined rubber sheets; The refined film is placed in a cooling device, first cooled to 40° C. at a rate of 10-15° C. / min, and then naturally cooled to below 25° C. for storage.

2. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: When adding the vulcanizing agent, the material is added in stages: First, add 50% of the vulcanizing agent and mix with CM3510 and dioctyl ester for 3 minutes; The remaining vulcanizing agent, activating agent and lubricant are added when the temperature is ≥80℃.

3. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: During the refining process of the second open mill, a release agent prepared by mixing silicone oil and anhydrous ethanol at a ratio of 1:5 is sprayed onto the surface of the rubber compound, with the spraying amount being 0.1-0.3% of the weight of the flaked rubber compound.

4. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: The cooling device is an inert gas protection cabin with a gas dew point of ≤-40°C and an oxygen concentration of ≤100ppm.

5. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: The vulcanizing agent comprises sulfur, an accelerator TMTD and an unsaturated fatty acid zinc salt, and the mass ratio of the three is (40-45): (8-10): (2-3).

6. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: Before putting into the internal mixer, premix dioctyl ester and CM3510 at 60±5℃ for 10~15 minutes to form a pre-swelling rubber compound. The premixing stirring speed is 200~300 rpm.

7. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: The first open mill uses a spiral groove roller with a groove depth of 0.5~1mm and a pitch angle of 30°~45°. The rubber material is subjected to a shear rate of ≥500s when passing through the roller gap. -1 .

8. The method for preparing a soft vulcanizing agent film according to claim 4, wherein: The inert gas protection cabin is provided with a hydraulic pressure platform. After cooling to 40°C at a rate of 10-15°C / min, the following steps are further included: Applying a vertical pressure of 0.5-1 MPa to the film through the hydraulic platform for 2-3 minutes, and maintaining the oxygen concentration in the inert gas protection chamber ≤ 100 ppm during the pressurization process; The natural cooling to below 25° C. for storage comprises the following steps: After the pressure holding is completed, cool naturally to below 25℃ for storage.

9. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: The lubricant is a compound of oxidized polyethylene wax and calcium stearate, with a mass ratio of 1:1 and a melting point of 115-125°C.

10. The method for preparing a soft vulcanizing agent film according to claim 1, wherein: The active agent is a composite system of nano zinc oxide and organic zinc complex, wherein: Nano zinc oxide particle size is 20~50nm, specific surface area is 30~50m² / g; The organic zinc complex is a mixture of zinc ethylenediaminetetraacetate and zinc dimercaptobenzothiazole in a mass ratio of 1:(0.3~0.5); The mass ratio of nano zinc oxide to organic zinc complex in the composite system is (0.6-0.8):1.

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