A full-spectrum chemical long-acting protective rubber film composite structure and a preparation method thereof

Abstract

The application discloses a long-acting protective rubber film composite structure of full-spectrum chemicals and a preparation method thereof, relates to the technical field of high polymer composite materials, and aims to solve the technical problem that current protective materials are difficult to realize long-acting and reliable protection due to narrow protection spectrum or weak interlayer bonding force. The composite structure is a functional gradient system of multiple layers of polymer materials with different properties. The outer layer and the inner layer are chemically bonded through an interface bonding layer. The composite structure comprises, from outside to inside, a chemical corrosion-resistant elastomer layer, an interface bonding layer and a high-barrier resin layer. The layers are firmly combined through a chemically bonded interface formed by a synchronous co-sulfurization process. The application builds a clear functional gradient protection system. The chemical corrosion-resistant elastomer of the outer layer serves as the first line of defense, and the high-barrier resin of the inner layer serves as the core barrier. The interface bonding layer connects them, so that they can calmly cope with full-spectrum chemicals from inorganic acids and bases to organic solvents.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and more specifically, to a long-lasting protective rubber film composite structure for a full spectrum of chemicals and its preparation method. Background Technology

[0002] In numerous fields such as chemical production, hazardous chemical storage and transportation, environmental governance, emergency rescue, and military special applications, protective materials have long faced the challenges of complex and harsh chemical environments. In these scenarios, protective materials need to resist the erosion of various types of chemicals, including acids, alkalis, oils, esters, ketones, alcohols, and hydrocarbons. At the same time, they must also adapt to complex working conditions such as alternating high and low temperatures, frequent bending, and vibration, placing extremely high demands on their chemical stability, structural integrity, and long-term durability.

[0003] Existing protective solutions mainly rely on single polymer materials (such as fluororubber and nitrile rubber) or simple physical bonding composite structures. While single materials perform well in certain specific media, their protective spectrum is narrow and insufficient to cope with complex and diverse chemical environments. Simple physical bonding composite structures, on the other hand, rely solely on physical adhesion between layers, resulting in weak interfacial bonding strength. Under long-term penetration, swelling, and dynamic stress from chemical media, they are prone to interfacial delamination, blistering, or peeling, leading to rapid failure of protective function and failing to meet the requirements for long-term safety protection. Therefore, we propose a long-lasting protective rubber film composite structure for a full spectrum of chemicals and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art, adapt to practical needs, and provide a long-lasting protective rubber film composite structure for a full spectrum of chemicals and its preparation method, so as to solve the technical problem that current protective materials are difficult to achieve long-lasting and reliable protection due to their narrow protective spectrum or weak interlayer bonding.

[0005] To address the aforementioned technical problems, one objective of this invention is to provide a long-lasting protective rubber film composite structure for a full spectrum of chemicals. This composite structure is a multilayer functional gradient system of polymer materials with different properties. The outer and inner layers are chemically bonded through an interfacial bonding layer. From the outside to the inside, the composite structure consists of a chemically resistant elastomer layer, an interfacial bonding layer, and a high-barrier resin layer. Each layer is firmly bonded to the others through a chemical bonding interface formed by a simultaneous co-vulcanization process. The composite structure comprises the following components by weight: chemically resistant... The outer layer comprises 30-60 parts of a resistant elastomer layer, 15-40 parts of an interfacial bonding layer, and 8-20 parts of a high-barrier resin layer. The interfacial bonding layer is a composite system containing a polymer graft copolymer and nanofillers. The interfacial bonding layer is composed of the following components by weight: 80-97 parts of a polymer graft copolymer and 3-20 parts of nanofillers. The chemically resistant elastomer outer layer includes a fluororubber layer, a chloroprene rubber layer, or a hydrogenated nitrile rubber layer. The high-barrier resin layer includes an ethylene-vinyl alcohol copolymer film and an ethylene-vinyl alcohol copolymer composite film.

[0006] Preferably, the polymer graft copolymer is a fluororubber-g-ethylene-vinyl alcohol copolymer graft copolymer or an nitrile rubber-g-ethylene-vinyl alcohol copolymer graft copolymer. Due to the large polarity difference between the outer layer of the fluororubber and the inner layer of the ethylene-vinyl alcohol copolymer film, the direct composite interface bonding is weak. The graft copolymer is selected because part of its molecular chain is compatible with fluororubber, and the other part is similar in structure to the ethylene-vinyl alcohol copolymer film, which can form an effective molecular bridge between the two layers. During the synchronous co-vulcanization process, the graft copolymer can form chemical bonds with the adjacent layers, achieve a smooth polarity transition, and increase the interlayer bonding force.

[0007] Preferably, the nanofiller is nano-montmorillonite or nano-silica modified with a silane coupling agent. The introduction of the nanofiller is intended to strengthen and toughen the interfacial bonding layer. After modification with a silane coupling agent, the functional groups on the surface of the filler can generate strong interactions with the polymer matrix. The nanoparticles can serve as physical crosslinking points, improving the modulus, strength, and creep resistance of the interfacial layer, and can passivate crack tips, thereby improving the fatigue resistance and long-term durability of the composite film.

[0008] The second objective of this invention is to provide a method for preparing the above-mentioned long-lasting protective rubber film composite structure for a full spectrum of chemicals, comprising the following steps:

[0009] (1) The polymer graft copolymer of the interface bonding layer is dry mixed with the nanofiller, then melt-blended and granulated by a twin-screw extruder, and then calendered into a film by a calender to obtain the interface bonding layer film.

[0010] (2) A chemical corrosion resistant elastomer layer, an interfacial bonding layer and a high barrier resin layer are sequentially bonded together using a reactive adhesive and then pre-cured to obtain a composite preform.

[0011] (3) Place the composite preform obtained in step (2) in a vulcanization equipment and perform synchronous co-vulcanization molding so that each layer forms a chemical bonding interface with the synchronous co-vulcanization process through the reactive adhesive to obtain the final composite rubber film product.

[0012] Preferably, the dry mixing conditions in step (1) are: room temperature, speed of 250-350 rpm, and dry mixing time of 4-6 minutes; the barrel temperature zones of the twin-screw extruder are: zone 1 135-145℃, zone 2 145-155℃, zone 3 150-160℃, and die head temperature 155-165℃; the screw speed is 45-55 rpm.

[0013] Preferably, the reactive adhesive in step (2) is a polyurethane adhesive or an epoxy resin adhesive.

[0014] Preferably, the polyurethane adhesive is an epoxy-modified polyurethane adhesive or a water-based polyurethane adhesive.

[0015] Preferably, in step (2), the amount of adhesive applied between the elastomer layer and the interface bonding layer is 80-100 g / m², the pre-curing temperature is 80-90°C, and the time is 20-25 minutes; the amount of adhesive applied between the interface bonding layer and the resin layer is 60-80 g / m², the pre-curing temperature is 70-80°C, and the time is 15-20 minutes.

[0016] Preferably, the synchronous co-vulcanization molding operation in step (3) is carried out at 160-170℃ and 10-12MPa, and the vulcanization time is 30-45 minutes.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention constructs a functionally defined gradient protection system. The outer layer, a chemically resistant elastomer, serves as the first line of defense. Its superior chemical inertness preferentially resists the erosion of strong acids, strong oxidants, and various organic solvents, and withstands the main mechanical wear. The inner layer, a high-barrier resin, acts as the core barrier, its dense molecular structure significantly delaying or blocking the penetration of chemical molecules. These two lines of defense are organically connected through an interfacial bonding layer, forming a synergistic mechanism of resistance and barrier. This enables the system to effectively cope with a full spectrum of chemicals, from inorganic acids and alkalis to organic solvents, solving the problem that current protective materials often fail to achieve long-term reliable protection due to their narrow protective spectrum or weak interlayer bonding.

[0019] 2. This invention also features a specially designed interfacial bonding layer. The grafted copolymer molecular structure employed in this layer possesses excellent compatibility with adjacent layers. During simultaneous co-curing, it acts as a molecular bridge, chemically reacting with the elastomer and resin layers on both sides to form strong covalent bonds. The strength of these interfacial chemical bonds is far greater than the physical adsorption force provided by traditional adhesives, resulting in an order-of-magnitude increase in interlayer peel strength. Therefore, this composite structure effectively resists swelling stress, thermal stress, and dynamic bending stress caused by long-term chemical immersion, preventing early failure of protective functions due to interfacial debonding, blistering, and delamination, thus ensuring the long-term structural integrity of the product under harsh environments. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available. For any specific techniques or conditions not specified in the examples, they can be carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0022] A long-lasting protective rubber film composite structure for a full spectrum of chemicals is disclosed. This composite structure is a multilayer functionally graded system of polymer materials with different properties. The outer and inner layers are chemically bonded through an interfacial bonding layer. From the outside to the inside, the composite structure consists of a chemically resistant elastomer layer, an interfacial bonding layer, and a high-barrier resin layer. Each layer is firmly bonded to the others through a chemical bonding interface formed by a simultaneous co-vulcanization process. The composite structure comprises the following components by weight: 30-60 parts of the chemically resistant elastomer layer, 15-40 parts of the interfacial bonding layer, and 8-20 parts of the high-barrier resin layer. The chemically resistant elastomer outer layer includes a fluororubber layer, a chloroprene rubber layer, or a hydrogenated nitrile rubber layer. The interfacial bonding layer is a composite system containing polymer graft copolymers and nanofillers. The high-barrier resin layer includes an ethylene-vinyl alcohol copolymer film and an ethylene-vinyl alcohol copolymer composite film.

[0023] Due to the large polarity difference between the outer layer of fluororubber and the inner layer of the ethylene-vinyl alcohol copolymer film, the direct composite interface bonding is weak. The graft copolymer is selected because part of its molecular chain is compatible with fluororubber, and the other part is similar in structure to the ethylene-vinyl alcohol copolymer film, which can form an effective molecular bridge between the two layers. During the synchronous co-vulcanization process, the graft copolymer can form chemical bonds with adjacent layers, achieve a smooth polarity transition, and increase the interlayer bonding force. Therefore, the present invention uses fluororubber-g-ethylene-vinyl alcohol copolymer graft copolymer or nitrile rubber-g-ethylene-vinyl alcohol copolymer graft copolymer as the polymer graft copolymer.

[0024] The nanofiller is introduced to enhance and toughen the interfacial bonding layer. After modification with a silane coupling agent, the functional groups on the filler surface can interact strongly with the polymer matrix. The nanoparticles can serve as physical crosslinking points, improving the modulus, strength, and creep resistance of the interfacial layer, and can also passivate crack tips, thereby improving the fatigue resistance and long-term durability of the composite film. Therefore, this invention uses nano-montmorillonite or nano-silica modified with a silane coupling agent as the nanofiller.

[0025] Example 1

[0026] This embodiment provides a method for preparing a long-lasting protective rubber film composite structure for a full spectrum of chemicals, including the following steps:

[0027] (1) 23.75g of fluororubber-g-ethylene vinyl alcohol copolymer graft copolymer and 1.25g of nano-montmorillonite modified with silane coupling agent were placed in a high-speed mixer with a volume of 1L and dry-mixed for 5 minutes at room temperature and a speed of 300 rpm to obtain mixed powder;

[0028] The obtained mixed powder is continuously and stably fed into a co-rotating twin-screw extruder at a rate of 2.0 kg / h using a loss-in-weight feeder. Under the set temperature process, the barrel temperature is divided into three zones: zone 1 140℃, zone 2 150℃, zone 3 155℃, and die head 160℃. The mixture is melt-blended, devolatilized, and homogenized at a screw speed of 50 rpm. The extruded strip is cooled and solidified in a cooling water tank at a temperature of 25±2℃, and then cut into cylindrical pellets with uniform particle size by a pelletizer.

[0029] The obtained granules are fed into a two-roll precision calender and calendered under the conditions of a roll temperature of 130°C and a roll gap of 0.30 mm to finally obtain an interfacial bonding layer film.

[0030] (2) On the 40g fluororubber outer layer, use a precision scraper to uniformly coat the epoxy modified polyurethane adhesive, control the wet film thickness so that the coating amount is 90g / ㎡, immediately attach the interfacial bonding layer film obtained in step (1) to the adhesive surface, and use a rubber roller to roll back and forth 3 times with a pressure of 0.2MPa to completely remove the interfacial bubbles. Then place the bonded blank in a forced-air oven and preheat and cure it at 85℃ for 22 minutes.

[0031] On the other side of the pre-cured interfacial bonding layer, water-based polyurethane adhesive is uniformly coated using a wire bar coater, with the coating amount controlled at 70g / ㎡. Then, a 10g ethylene-vinyl alcohol copolymer film is covered on top. After being degassed by roller pressing, it is transferred to another oven and preheated and cured at 75℃ for 18 minutes to obtain the composite preform.

[0032] (3) Place the composite blank obtained in step (2) flat into the mold cavity of the 400-ton flat vulcanizing machine, close the mold, raise the pressure to 11MPa within 30 seconds, and start the heating program. Within 5 minutes, raise the mold temperature to 165℃ uniformly. Maintain this temperature and pressure for 35 minutes to carry out the synchronous co-vulcanization reaction.

[0033] After vulcanization, the heating is turned off, the pressure is kept constant, and the built-in circulating water cooling system of the vulcanizing machine is started to slowly cool the mold at a rate not exceeding 3℃ / minute. When the mold temperature drops below 80℃, the pressure is released and the mold is opened to remove the product. Finally, after curing at room temperature (23±2℃) for 24 hours and trimming and inspection, the final composite rubber film product is obtained.

[0034] Example 2

[0035] This embodiment provides a method for preparing a long-lasting protective rubber film composite structure for a full spectrum of chemicals, including the following steps:

[0036] (1) 23.75g of fluororubber-g-ethylene vinyl alcohol copolymer graft copolymer and 1.25g of nano-montmorillonite modified with silane coupling agent were placed in a high-speed mixer with a volume of 1L and dry-mixed for 5 minutes at room temperature and a speed of 300 rpm to obtain mixed powder;

[0037] The obtained mixed powder is continuously and stably fed into a co-rotating twin-screw extruder at a rate of 2.0 kg / h using a loss-in-weight feeder. Under the set temperature process, the barrel temperature is divided into three zones: zone 1 140℃, zone 2 150℃, zone 3 155℃, and die head 160℃. The mixture is melt-blended, devolatilized, and homogenized at a screw speed of 50 rpm. The extruded strip is cooled and solidified in a cooling water tank at a temperature of 25±2℃, and then cut into cylindrical pellets with uniform particle size by a pelletizer.

[0038] The obtained granules are fed into a two-roll precision calender and calendered under the conditions of a roll temperature of 130°C and a roll gap of 0.30 mm to finally obtain an interfacial bonding layer film.

[0039] (2) On the 50g fluororubber outer layer, use a precision scraper to uniformly coat the epoxy modified polyurethane adhesive, control the wet film thickness so that the coating amount is 90g / ㎡, immediately attach the interfacial bonding layer film obtained in step (1) to the adhesive surface, and use a rubber roller to roll back and forth 3 times with a pressure of 0.2MPa to completely remove the interfacial bubbles. Then place the bonded blank in a forced-air oven and preheat and cure it at 85℃ for 22 minutes.

[0040] On the other side of the pre-cured interfacial bonding layer, water-based polyurethane adhesive is uniformly coated using a wire bar coater, with the coating amount controlled at 70g / ㎡. Then, a 10g ethylene-vinyl alcohol copolymer film is covered on top. After being degassed by roller pressing, it is transferred to another oven and preheated and cured at 75℃ for 18 minutes to obtain the composite preform.

[0041] (3) Place the composite blank obtained in step (2) flat into the mold cavity of the 400-ton flat vulcanizing machine, close the mold, raise the pressure to 11MPa within 30 seconds, and start the heating program. Within 5 minutes, raise the mold temperature to 165℃ uniformly. Maintain this temperature and pressure for 35 minutes to carry out the synchronous co-vulcanization reaction.

[0042] After vulcanization, the heating is turned off, the pressure is kept constant, and the built-in circulating water cooling system of the vulcanizing machine is started to slowly cool the mold at a rate not exceeding 3℃ / minute. When the mold temperature drops below 80℃, the pressure is released and the mold is opened to remove the product. Finally, after curing at room temperature (23±2℃) for 24 hours and trimming and inspection, the final composite rubber film product is obtained.

[0043] Example 3

[0044] This embodiment provides a method for preparing a long-lasting protective rubber film composite structure for a full spectrum of chemicals, including the following steps:

[0045] (1) 23.75g of fluororubber-g-ethylene vinyl alcohol copolymer graft copolymer and 1.25g of nano-montmorillonite modified with silane coupling agent were placed in a high-speed mixer with a volume of 1L and dry-mixed for 5 minutes at room temperature and a speed of 300 rpm to obtain mixed powder;

[0046] The obtained mixed powder is continuously and stably fed into a co-rotating twin-screw extruder at a rate of 2.0 kg / h using a loss-in-weight feeder. Under the set temperature process, the barrel temperature is divided into three zones: zone 1 140℃, zone 2 150℃, zone 3 155℃, and die head 160℃. The mixture is melt-blended, devolatilized, and homogenized at a screw speed of 50 rpm. The extruded strip is cooled and solidified in a cooling water tank at a temperature of 25±2℃, and then cut into cylindrical pellets with uniform particle size by a pelletizer.

[0047] The obtained granules are fed into a two-roll precision calender and calendered under the conditions of a roll temperature of 130°C and a roll gap of 0.30 mm to finally obtain an interfacial bonding layer film.

[0048] (2) On the 60g fluororubber outer layer, use a precision scraper to uniformly coat the epoxy modified polyurethane adhesive, control the wet film thickness so that the coating amount is 90g / ㎡, immediately attach the interface bonding layer film obtained in step (1) to the adhesive surface, and use a rubber roller to roll back and forth 3 times with a pressure of 0.2MPa to completely remove interface bubbles. Then place the bonded blank in a forced-air oven and preheat and cure at 85℃ for 22 minutes.

[0049] On the other side of the pre-cured interfacial bonding layer, water-based polyurethane adhesive is uniformly coated using a wire bar coater, with the coating amount controlled at 70g / ㎡. Then, a 10g ethylene-vinyl alcohol copolymer film is covered on top. After being degassed by roller pressing, it is transferred to another oven and preheated and cured at 75℃ for 18 minutes to obtain the composite preform.

[0050] (3) Place the composite blank obtained in step (2) flat into the mold cavity of the 400-ton flat vulcanizing machine, close the mold, raise the pressure to 11MPa within 30 seconds, and start the heating program. Within 5 minutes, raise the mold temperature to 165℃ uniformly. Maintain this temperature and pressure for 35 minutes to carry out the synchronous co-vulcanization reaction.

[0051] After vulcanization, the heating is turned off, the pressure is kept constant, and the built-in circulating water cooling system of the vulcanizing machine is started to slowly cool the mold at a rate not exceeding 3℃ / minute. When the mold temperature drops below 80℃, the pressure is released and the mold is opened to remove the product. Finally, after curing at room temperature (23±2℃) for 24 hours and trimming and inspection, the final composite rubber film product is obtained.

[0052] Comparative Example 1: Ordinary nitrile rubber interlayer composite film:

[0053] (1) 25 parts of nitrile rubber compound were thinly sheeted on a two-roll mill. The NBR raw rubber sheet was calendered into a film with a thickness of 0.30±0.02mm on a calender.

[0054] All parameters of the composite pretreatment and synchronous co-vulcanization process in steps (2) and (3) are strictly consistent with those in Example 1 to obtain a common nitrile rubber interlayer composite film.

[0055] Comparative Example 2: Physically bonded composite film:

[0056] (1) 40 parts of fluororubber compound were vulcanized separately in a flat vulcanizing machine at 165°C and 11MPa for 35 minutes to obtain fluororubber vulcanized sheets.

[0057] (2) The bonding surfaces of the fluororubber vulcanized film are subjected to corona treatment to increase the surface energy. The same epoxy-modified polyurethane adhesive as in Example 1 is uniformly coated on the treated fluororubber vulcanized film and ethylene-vinyl alcohol copolymer film. The coating amount is 90 g / m². The two layers of materials are bonded together, rolled to remove air, and the bonded body is placed in an oven and cured at 80°C for 2 hours to allow the adhesive to cure completely, thus obtaining a physically bonded composite film.

[0058] Comparative Example 3: Single fluororubber membrane:

[0059] 50 parts of FKM compound were vulcanized at 165℃ and 11MPa for 35 minutes to obtain a homogeneous fluororubber vulcanized sheet with a thickness of about 1.5mm.

[0060] Comparative Example 4: Single ethylene-vinyl alcohol copolymer film:

[0061] Commercially available ethylene-vinyl alcohol copolymer films with a thickness of 0.15 mm were used directly as test samples without any composite or lamination treatment.

[0062] The performance of Example 1: composite rubber film, Comparative Example 1: ordinary nitrile rubber interlayer composite film, Comparative Example 2: physical bonding composite film, Comparative Example 3: single fluororubber film, and Comparative Example 4: single ethylene-vinyl alcohol copolymer film were compared by performance testing. The test results are listed in Tables 1, 2, 3, and 4.

[0063] Table 1. Comparison of interlayer bond performance test results:

[0064] Table 1 aims to quantitatively assess the interfacial bonding strength between the layers of the composite structure. This characteristic is the basis for ensuring that the composite material does not delaminate under stress or harsh environments, and maintains the integrity of the overall structure and long-term protective function.

[0065] Specific testing method: The interlayer peel strength of the composite film sample was measured using the 180° peel method;

[0066] The sample was cut into strips of a specified width and peeled at a constant speed of 180° on a universal testing machine. The peel strength ( The value is calculated by the average force during the peeling process, and it directly reflects the strength of the interlayer bond.

[0067] Table 1. Comparison of interlayer bonding performance

[0068]

[0069] As shown in Table 1, Example 1, employing the scheme of the present invention, exhibited the highest interlayer bond strength in the 180° peel test, with a peel strength as high as 13.2. This is thanks to the polar transition-mechanically reinforced interface layer composed of fluororubber-g-ethylene vinyl alcohol copolymer, which forms an interpenetrating network chemical bonding interface with the outer layer of fluororubber and the inner layer of ethylene-vinyl alcohol copolymer film under the simultaneous co-vulcanization process, mainly composed of covalent and ionic bonds, thus constructing an extremely strong interlayer bond.

[0070] In contrast, although Comparative Example 1 used the same process, the large polarity difference and poor compatibility between the nitrile rubber and the fluororubber and ethylene-vinyl alcohol copolymer films prevented effective interfacial chemical bonding, resulting in a peel strength of only 5.5. ;

[0071] Comparative Example 2 relies entirely on the physical adhesion of the adhesive and lacks the chemical bonds formed during simultaneous vulcanization. Its interfacial bonding is the weakest, with a peel strength of only 3.0. ;

[0072] Comparative Example 1 and Comparative Example 4 are homogeneous materials without interlayer interfaces, therefore their peel strength is not applicable to this test.

[0073] Table 2. Results of chemical resistance test:

[0074] Table 2 aims to systematically evaluate the volume stability and chemical resistance of the composite structure in a full spectrum of chemicals, including acids, alkalis, and organic solvents. This characteristic is the core indicator for evaluating whether it can achieve long-term protection across the entire spectrum.

[0075] Specific detection method: The volume change rate of the sample is measured using the immersion method in a specific chemical medium.

[0076] The sample is completely immersed in a chemical reagent of a specified concentration (such as 25% sulfuric acid, 40% sodium hydroxide, acetone, etc.) and kept at a constant temperature of 23°C for 168 hours. After removal, the surface liquid is quickly blotted dry with filter paper, and the volume before and after immersion is measured. The volume change rate, i.e., the degree of swelling, is given by the formula: Calculate, where, For the initial volume, This represents the volume after soaking.

[0077] Table 2. Comparison of chemical resistance properties

[0078]

[0079] As shown in Table 2, Example 1 using the scheme of the present invention exhibits excellent and balanced chemical stability in 25% sulfuric acid, 40% sodium hydroxide, and acetone, with volume changes of 6.2%, 4.8%, and 11.5% after 168 hours, respectively, all remaining at low levels. This is due to the gradient synergistic design of the corrosion-resistant fluororubber outer layer, the interfacial bonding layer, and the high-barrier EVOH inner layer. The fluororubber effectively resists the erosion of acids and solvents, the ethylene-vinyl alcohol copolymer film inner layer provides excellent alkali resistance and barrier properties, and the tough interfacial bonding layer ensures the integrity of the structure, achieving true full-spectrum chemical protection.

[0080] In contrast, Comparative Example 1, due to the fact that the intermediate layer of nitrile rubber is not resistant to alkali and acetone, swells severely in 40% sodium hydroxide and dissolves and fails in acetone.

[0081] Comparative Example 2, due to its weak physical bonding interface, experienced significant interface damage (bubbling, peeling, or delamination) in all three media, resulting in a complete loss of protective function.

[0082] Comparative Example 3 performed reasonably well in acid, but had extremely poor alkali resistance, with a volume change rate of 45.2%, and was soluble in acetone, indicating a narrow protective spectrum.

[0083] Comparative Example 4 is stable in alkali, but becomes brittle and crumbles when exposed to strong acid, and dissolves in acetone. Its mechanical integrity and chemical resistance cannot meet the actual protection requirements.

[0084] Table 3. Results of anti-permeability test:

[0085] Table 3 aims to accurately assess the rate at which chemical vapors (such as xylene) penetrate composite structural materials, a characteristic that directly determines the safe service life and long-term effectiveness of protective materials.

[0086] Specific testing method: The penetration breakthrough time of a specific chemical is measured using the standard test cell method.

[0087] The sample is sealed as a diaphragm in a dedicated permeation test cell, with a liquid challenge chemical (such as xylene) on one side and a flowing carrier gas (such as nitrogen) on the other. The concentration of the chemical vapor in the carrier gas is continuously monitored using gas chromatography or a dedicated sensor. The time elapsed from the start of the test until the chemical permeation rate measured by the detector reaches a predetermined threshold is recorded; this is the permeation breakthrough time.

[0088] Table 3. Comparison of anti-permeability performance

[0089]

[0090] As shown in Table 3, Example 1 using the scheme of the present invention exhibits a penetration time of more than 780 minutes for xylene, demonstrating excellent long-term barrier performance. This is due to its gradient structure: the fluororubber outer layer acts as the first barrier, consuming and delaying the attack of the medium, while protecting the core ethylene-vinyl alcohol copolymer film's high-barrier inner layer, enabling it to exert its ultimate barrier effect for a long time and efficiently, thus achieving a synergistic effect of long-term protection.

[0091] In contrast, Comparative Example 1 showed a significantly reduced xylene breakthrough time of 150 minutes due to poor barrier properties of the intermediate layer and weak interfacial bonding.

[0092] Comparative Example 2 has a physically bonded interface that is easily penetrated, allowing the medium to diffuse rapidly along the interface, resulting in the shortest breakthrough time.

[0093] Comparative Example 3, due to its rubber-like nature, has a large molecular chain spacing and limited barrier properties against small molecule solvents, resulting in a breakthrough time of only 280 minutes.

[0094] Although Comparative Example 4 has the best intrinsic barrier properties, its material is extremely brittle and prone to mechanical failure during actual testing or use, so its excellent barrier performance cannot be demonstrated when used independently.

[0095] Table 4. Results of Mechanical Durability Tests:

[0096] Table 4 aims to evaluate the composite structure's ability to withstand dynamic bending stress and its service life. This characteristic reflects the material's reliability and durability under actual frequent bending and deformation conditions.

[0097] Specific testing method: The sample is repeatedly bent until failure is achieved using a dynamic bending fatigue testing machine.

[0098] The sample strip is fixed on the testing machine and subjected to continuous, reciprocating bending motion under constant stroke and bending radius. The number of bending cycles before the sample first shows a visible crack or completes fracture is recorded. This number of cycles is the dynamic bending fatigue life of the material.

[0099] Table 4. Mechanical Durability Comparison

[0100]

[0101] As shown in Table 4, Example 1 using the scheme of the present invention exhibits a lifespan exceeding 16,000 cycles in dynamic bending fatigue testing, demonstrating exceptional mechanical durability. This is attributed to the strong and tough chemically bonded interface, which effectively transfers and disperses stress, while the gradient modulus design avoids stress concentration, allowing the composite structure to maintain its integrity under repeated bending.

[0102] In contrast, Comparative Example 1, due to its weaker interfacial bonding, is prone to microcracks and propagation under cyclic stress, resulting in a significant reduction in fatigue life to approximately 4000 cycles.

[0103] The physical bonding interface of Comparative Example 2 debonded rapidly under dynamic load, resulting in the shortest fatigue life of only about 2000 cycles.

[0104] Comparative Example 3, as an elastomer, has a certain degree of fatigue resistance, but it is still inferior to the composite reinforced structure of the present invention.

[0105] Comparative Example 4, due to the inherent brittleness of the material, has almost no flexibility and fractures brittlely after less than 100 bends, completely failing to meet the mechanical requirements of flexible protective materials.

[0106] In summary, this invention constructs a functionally defined gradient protection system. The outer layer, a chemically resistant elastomer, serves as the first line of defense. Its superior chemical inertness preferentially resists the erosion of strong acids, strong oxidants, and various organic solvents, while also withstanding major mechanical wear. The inner layer, a high-barrier resin, acts as the core barrier, its dense molecular structure significantly delaying or blocking the penetration of chemical molecules. These two lines of defense are organically linked through an interfacial bonding layer, forming a synergistic mechanism of resistance and barrier. This enables the system to effectively cope with a full spectrum of chemicals, from inorganic acids and alkalis to organic solvents, solving the problem that current protective materials often fail to achieve long-term reliable protection due to their narrow protective spectrum or weak interlayer bonding.

[0107] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A composite structure of a long-lasting protective rubber film for a full spectrum of chemicals, characterized in that, The composite structure is a multilayer functional gradient system of polymer materials with different properties. The outer and inner layers are chemically bonded through an interfacial bonding layer. The composite structure consists of a chemically resistant elastomer layer, an interfacial bonding layer, and a high-barrier resin layer from the outside to the inside. The layers are firmly bonded to each other through a chemical bonding interface formed by a simultaneous co-vulcanization process. The composite structure is composed of the following components in parts by weight: 30-60 parts of chemically resistant elastomer layer, 15-40 parts of the interface bonding layer, and 8-20 parts of high-barrier resin layer. The interface bonding layer is a composite system comprising polymer graft copolymer and nanofiller; The interface bonding layer is composed of the following components in parts by weight: 80-97 parts of polymer graft copolymer, 3-20 parts of nanofiller; The chemically resistant elastomer outer layer includes a fluororubber layer, a chloroprene rubber layer, or a hydrogenated nitrile rubber layer. The high-barrier resin layer includes an ethylene-vinyl alcohol copolymer film and an ethylene-vinyl alcohol copolymer composite film.

2. The long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 1, characterized in that, The polymer graft copolymer is a fluororubber-g-ethylene vinyl alcohol copolymer graft copolymer or a nitrile rubber-g-ethylene vinyl alcohol copolymer graft copolymer.

3. The long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 1, characterized in that, The nanofiller is nano-montmorillonite or nano-silica modified with a silane coupling agent.

4. A method for preparing a long-lasting protective rubber film composite structure for a full spectrum of chemicals, applicable to the long-lasting protective rubber film composite structure for a full spectrum of chemicals as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) The polymer graft copolymer of the interface bonding layer is dry mixed with the nanofiller, then melt-blended and granulated by a twin-screw extruder, and then calendered into a film by a calender to obtain the interface bonding layer film. (2) A chemical corrosion resistant elastomer layer, an interfacial bonding layer and a high barrier resin layer are sequentially bonded together using a reactive adhesive and then pre-cured to obtain a composite preform. (3) Place the composite preform obtained in step (2) in a vulcanization equipment and perform synchronous co-vulcanization molding so that each layer forms a chemical bonding interface with the synchronous co-vulcanization process through the reactive adhesive to obtain the final composite rubber film product.

5. The method for preparing the long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 4, characterized in that, The dry mixing conditions in step (1) are: room temperature, speed of 250-350 rpm, and dry mixing time of 4-6 minutes; The barrel temperature zones of the twin-screw extruder are: Zone 1 135-145℃, Zone 2 145-155℃, Zone 3 150-160℃, and the die head temperature 155-165℃. The screw speed is 45-55 revolutions per minute.

6. The method for preparing the long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 4, characterized in that, The reactive adhesive mentioned in step (2) is a polyurethane adhesive or an epoxy resin adhesive.

7. The method for preparing the long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 6, characterized in that, The polyurethane adhesive is an epoxy-modified polyurethane adhesive or a water-based polyurethane adhesive.

8. The method for preparing the long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 4, characterized in that, In step (2), the amount of adhesive applied between the elastomer layer and the interface bonding layer is 80-100 g / m², the pre-curing temperature is 80-90°C, and the time is 20-25 minutes. The amount of adhesive applied between the interface bonding layer and the resin layer is 60-80 g / m², the pre-curing temperature is 70-80℃, and the time is 15-20 minutes.

9. The method for preparing the long-lasting protective rubber film composite structure for a full spectrum of chemicals according to claim 4, characterized in that: In step (3), the simultaneous co-vulcanization molding operation is carried out at 160-170℃ and 10-12MPa, and the vulcanization time is 30-45 minutes.

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