A sealing ring adhesive, its preparation method and application

Abstract

The present application relates to the technical field of adhesive, in particular to a kind of adhesive for sealing ring and its preparation method and application, the adhesive for sealing ring, by weight parts, including the following raw materials: modified fluorine rubber 90-110 parts, vulcanizing agent 4-5 parts, solvent 230-270 parts.The adhesive prepared by the present application has higher bonding strength, excellent temperature resistance and high compatibility with the base material.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to an adhesive for sealing rings, its preparation method, and its application. Background Technology

[0002] As a core component for sealing and protection, sealing rings are widely used in various industrial fields such as automobiles, machinery, electronics, and pipeline transportation. Their sealing performance directly determines the stability and safety of equipment operation. In the production and maintenance of sealing rings, adhesives are key materials for bonding and molding split sealing rings and repairing damaged sealing rings. Their bonding strength, environmental adaptability, and ease of construction have a decisive impact on the overall service quality of the sealing ring.

[0003] Currently, the mainstream adhesives for sealing rings on the market mainly include chloroprene adhesives, polysulfide adhesives, cyanoacrylate adhesives, and modified rubber-specific adhesives, each suitable for different substrates and operating conditions. Among them, cyanoacrylate adhesives offer fast positioning and are suitable for rapid bonding of small sealing rings; polysulfide and chloroprene adhesives are widely used in rubber-to-rubber bonding under ordinary operating conditions. However, with the development of industrial equipment towards high temperature, high pressure, and strong corrosion, and the increasing demands for sealing reliability in fields such as new energy vehicles and high-end equipment, existing adhesives are gradually revealing many technical shortcomings. For example, patent CN115505369A discloses a high tensile elongation silicone adhesive. This silicone adhesive includes a silicone adhesive base, silicone adhesive filler, and silicone adhesive additives. The silicone adhesive base is a mixture of polydimethylsiloxanes, the silicone adhesive filler is nano-light calcium carbonate, and the silicone adhesive additives consist of four reagents. The first reagent is a viscosity modifier, and the second reagent is a crosslinking agent. This invention effectively solves the problem of silicone adhesives being difficult to stretch by combining the silicone adhesive base, silicone adhesive filler, and silicone adhesive additives. By increasing the tensile strength of the silicone adhesive, the toughness and elasticity of the silicone sealing ring are improved, thereby extending the service life of the silicone sealing ring. Patent CN120758204B discloses a high thermal conductivity electronic packaging adhesive and its preparation method. This invention's high thermal conductivity electronic packaging adhesive, by weight, includes: 55 parts acrylate monomer. 60 parts, 40 parts methacrylate monomer 45 parts, photoinitiator 0.5 5 parts, modified boron nitride 10 25 parts, thixotropic agent 1 3 parts, defoamer 0.2 1 part and 0.5 part antioxidant One copy. This invention introduces a novel methacrylate monomer into the adhesive, endowing it with excellent hydrolysis resistance, effectively reducing its volume shrinkage rate, and improving its thermal conductivity. Furthermore, the modified boron nitride introduced into the adhesive prevents its aggregation, improves its dispersibility and compatibility, and further enhances the adhesive's thermal conductivity.

[0004] First, the core pain point is the insufficient adhesive strength and interfacial compatibility of the aforementioned adhesives. Common substrates for sealing rings, such as EPDM rubber and fluororubber, are mostly low surface energy materials. Traditional adhesives struggle to achieve good wetting, easily leading to interfacial delamination, brittle fracture, and other failures. Especially under cyclic vibration and thermal expansion / contraction conditions, cracks or even detachment can easily occur at the bonding joint, resulting in sealing failure and equipment malfunction. Second, their environmental adaptability is poor. Existing adhesives are prone to aging and degradation in high-temperature, humid, and corrosive environments, significantly reducing adhesive strength and failing to meet the long-term service requirements of special scenarios such as engine compartments and high-temperature industrial equipment.

[0005] Therefore, there is an urgent need in the market for an adhesive with high bonding strength, high temperature resistance, and good compatibility with the substrate interface. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain an adhesive for sealing rings that not only has high bonding strength and temperature resistance, but also good compatibility with the substrate interface.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides an adhesive for sealing rings, comprising, by weight, the following raw materials: 90-110 parts of modified fluororubber, 4-5 parts of vulcanizing agent, and 230-270 parts of solvent.

[0008] This invention firstly modifies fluororubber to enable it to form stronger chemical bonds with the sealing ring substrate, thereby fundamentally solving the problem of poor adhesion of conventional fluororubber. This gives the adhesive excellent initial adhesion and long-lasting interfacial stability. In addition, the modified fluororubber has better compatibility with solvents, which is conducive to obtaining a uniform adhesive solution with appropriate solid content and stable storage, avoiding the problems of difficult dissolution and easy gelation of unmodified fluororubber.

[0009] In some embodiments, the method for preparing the modified fluororubber includes the following steps: (1) Under nitrogen protection, p-phenylenediamine and 2-amino-isophthalaldehyde were added to DMF and stirred for 20-30 min. Then, a catalyst was added and the reaction was carried out at 130-140 °C for 40-50 h. The compound was obtained after post-treatment. (2) Add the compound obtained in step (1) along with fluororubber and dicyclohexylcarbodiimide into DMF and stir for 20-24 hours to obtain modified fluororubber.

[0010] Due to its low surface energy and strong chemical inertness, fluororubber adhesives often suffer from insufficient adhesion to substrates. Existing technologies typically improve adhesion by subjecting fluororubber to plasma or chemical etching surface treatments, or by blending it with tackifying resins. However, these methods offer limited improvement and may negatively impact the bulk properties. This invention grafts a compound generated from the reaction of p-phenylenediamine and 2-amino-isophthalaldehyde onto the fluororubber molecular chain. This introduces a rigid aromatic ring structure and polar groups into the fluororubber molecular chain. The aromatic ring structure may enhance the cohesive strength of the adhesive, while the polar groups significantly improve the physical adsorption and chemical interaction between the modified fluororubber and various substrate surfaces. Therefore, without sacrificing the inherent weather resistance and media resistance of fluororubber, its adhesive properties are fundamentally improved.

[0011] In some embodiments, the molar ratio of p-phenylenediamine to 2-aminoisophthalaldehyde is 1:(1-1.2).

[0012] In some embodiments, the fluororubber is a liquid-terminated carboxyl fluororubber.

[0013] In some embodiments, the mass ratio of the compound to the fluororubber in step (2) is (0.3-0.7):1.

[0014] In some embodiments, the catalyst is glacial acetic acid.

[0015] In some embodiments, the vulcanizing agent is a combination of triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0016] In some embodiments, the mass ratio of the triallyl isocyanurate to 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is (1.8-2.2):1.

[0017] In some embodiments, the solvent is methyl isobutyl ketone.

[0018] A second aspect of the present invention provides a method for preparing an adhesive for sealing rings, comprising the following steps: Add the modified fluororubber to the solvent and soak it at room temperature for 7-8 days. Then add the vulcanizing agent and stir for 5-10 minutes. Let it stand for 25-35 minutes to obtain the product.

[0019] The third aspect of the present invention provides a method for applying an adhesive for sealing rings, comprising the following steps: cutting a vulcanized rubber strip into a circular cross section, applying adhesive, and placing it at room temperature for 50-70 minutes; then aligning the two adhesive-coated surfaces together and placing them in a preheated mold, and vulcanizing at 155-165°C for 15-20 minutes.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The adhesive for sealing rings prepared by the present invention through modified silicone rubber, vulcanizing agent and solvent has high bonding strength, good temperature resistance and good compatibility with substrate.

[0021] (2) This invention modifies fluororubber to reduce its surface energy and enhance the cohesive strength of the adhesive, thereby improving the physical adsorption and chemical interaction between the modified fluororubber and the surfaces of various substrates, fundamentally improving its bonding performance without affecting the weather resistance and corrosion resistance of fluororubber.

[0022] (3) The adhesive prepared by the present invention can activate the vulcanizing agent in the adhesive layer through high temperature, so that it can not only be completely vulcanized, but also undergo interfacial co-crosslinking reaction with the vulcanization system in the rubber strip body on both sides, forming a three-dimensional network across the interface, thereby realizing the transition from "physical adhesion" to "chemical fusion", resulting in higher bonding strength and stronger temperature resistance. Attached Figure Description

[0023] Figure 1 A photograph of the adhesive prepared in Example 1; Figure 2 This is a photograph of the adhesive prepared in Example 1 applied to a fluororubber round strip. Figure 3 The adhesive prepared in Example 1 is shown in a photograph after vulcanization of fluororubber round bars. Detailed Implementation

[0024] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0025] In the following examples and comparative examples, the compounds and related reagents used were all commercially available. Among them, the adhesive JL-468 was purchased from Dongguan Juli Adhesive Products Co., Ltd.; the liquid carboxyl-terminated fluororubber CTFR, with a viscosity of 10-20 Pa·s (25°C), was purchased from Wuhan Kemic Biomedical Technology Co., Ltd.

[0026] Unless otherwise specified, the post-processing steps such as "washing", "drying", "stirring", and "extraction" used below are routine operations for those skilled in the art, and can be selected according to actual operation.

[0027] Preparation Example 1 The preparation method of modified fluororubber-1 includes the following steps: (1) Under nitrogen protection, 0.1 mol of p-phenylenediamine and 0.11 mol of 2-amino-isophthalaldehyde were added to 200 ml of DMF and stirred for 25 min. Then 60 g of 6 mol / L glacial acetic acid was added and reacted at 135 °C for 45 h. The temperature was lowered to room temperature, and the solid was washed with acetone and methanol after centrifugation and dried to obtain the compound. (2) Add 5g of the compound obtained in step (1), 10g of terminal carboxyl liquid fluororubber, and 5g of dicyclohexylcarbodiimide to 100ml of DMF, stir for 22h, wash with deionized water, extract with ethyl acetate, and dry to obtain modified fluororubber-1.

[0028] Preparation Example 2 The preparation method of modified fluororubber-2 is the same as that in preparation example 1, except that the amount of 2-amino-isophthalaldehyde added is 0.09 mol.

[0029] Preparation Example 3 The preparation method of modified fluororubber-3 is the same as that of preparation example 1, except that the amount of compound added in step (2) is 8g.

[0030] Example 1 An adhesive for sealing rings, comprising, by weight, the following raw materials: 100 parts modified fluororubber-1, 4.5 parts vulcanizing agent, and 250 parts methyl isobutyl ketone; The vulcanizing agent is a combination of triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in a mass ratio of 2:1.

[0031] The method for preparing the adhesive for the sealing ring in this embodiment includes the following steps: Modified fluororubber-1 is soaked in methyl isobutyl ketone at room temperature for 7-8 days, then a vulcanizing agent is added and stirred for 8 minutes, and allowed to stand for 30 minutes to obtain the product. Figure 1 As shown.

[0032] The method of applying adhesive to the sealing ring in this embodiment includes the following steps: A vulcanized FKM fluororubber strip with a diameter of 8mm is cut into a circular cross-section, and adhesive is applied to it to a thickness of 1±0.5mm (e.g., ...). Figure 2(As shown), place at room temperature for 60 minutes, then align the two adhesive-coated surfaces tightly together and place them in a preheated mold. Cure at 160°C for 18 minutes. The finished product is as follows. Figure 3 As shown.

[0033] Example 2 An adhesive for sealing rings, comprising, by weight, the following raw materials: 90 parts modified fluororubber-1, 4 parts vulcanizing agent, and 230 parts methyl isobutyl ketone; The vulcanizing agent is a combination of triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in a mass ratio of 1.8:1.

[0034] The method for preparing the adhesive for the sealing ring in this embodiment includes the following steps: Modified fluororubber-1 is soaked in methyl isobutyl ketone at room temperature for 7 days, then vulcanizing agent is added and stirred for 5 minutes, and then allowed to stand for 25 minutes to obtain the product.

[0035] The specific implementation method of the adhesive used for the sealing ring in this embodiment is the same as that in Embodiment 1.

[0036] Example 3 An adhesive for sealing rings, comprising, by weight, the following raw materials: 110 parts modified fluororubber-1, 5 parts vulcanizing agent, and 270 parts methyl isobutyl ketone; The vulcanizing agent is a combination of triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in a mass ratio of 2.2:1.

[0037] The method for preparing the adhesive for the sealing ring in this embodiment includes the following steps: Modified fluororubber-1 is soaked in methyl isobutyl ketone at room temperature for 8 days, then vulcanizing agent is added and stirred for 10 minutes, and then allowed to stand for 35 minutes to obtain the product.

[0038] The specific implementation method of the adhesive used for the sealing ring in this embodiment is the same as that in Embodiment 1.

[0039] Example 4 An adhesive for sealing rings, its preparation method and application method, are described in the same way as in Example 1, except that modified fluororubber-1 is replaced with modified fluororubber-2 in equal amounts.

[0040] Example 5 An adhesive for sealing rings, its preparation method and application method, are described in the same way as in Example 1, except that modified fluororubber-1 is replaced with modified fluororubber-3 in equal amounts.

[0041] Comparative Example 1 An adhesive for sealing rings and its preparation and application methods are disclosed. The specific implementation method is the same as that in Example 1, except that the modified fluororubber-1 is replaced with an equal amount of liquid-terminated carboxyl fluororubber.

[0042] Comparative Example 2 An adhesive for sealing rings, its preparation method and application method are disclosed. The specific implementation method is the same as that in Example 1, except that the adhesive is JL-468.

[0043] Performance testing 1. Adhesion: The adhesives obtained in each embodiment and comparative example were applied to rubber strips, and the following tests were performed using a Gottwell electronic universal tensile testing machine in accordance with standard ASTM D412. The test results are shown in Table 1: Table 1 As shown in Table 1, the adhesives prepared in Examples 1-3 have high bonding strength. A comparison of the data from Example 5 and Example 1 shows that changing the ratio of p-phenylenediamine to 2-aminoisophthalaldehyde may lead to a decrease in crosslinking density, weakened load-bearing capacity of the molecular chain network, reduced resistance to chain segment movement, easier chain slippage, decreased maximum force and 100% orientation force, and increased 5N elongation, indicating a decrease in adhesion. A comparison of the data from Example 5 and Example 1 shows that changing the ratio of the compound to fluororubber may cause some compounds within the modified fluororubber to be not chemically bonded, making them prone to dissociation and decreasing the maximum force. Simultaneously, the rigid groups of the free compound can still restrict chain movement, increasing 100% orientation stress, decreasing 5N elongation, and resulting in a decrease in overall adhesion. A comparison of Comparative Example 1 and Example 1 shows that directly using liquid-terminated carboxyl fluororubber as an adhesive results in a decrease in bonding strength. A comparison of Comparative Example 2 and Example 1 shows that the adhesive prepared in this invention has higher adhesion compared to ordinary commercially available adhesives.

[0044] 2. Temperature resistance Referring to the national standard GB / T 7124-2008, the tensile shear strength A0 of the finished rubber strips after applying the adhesives obtained in Examples 1-3 was tested. The strips were then placed at -20℃ and 250℃ for 72 hours, and the tensile shear strength A1 was tested again. The retention rate was calculated as (A1-A0) / A0×100%. The test results are shown in Table 2: Table 2 As can be seen from the data in Table 2, the adhesive prepared by this invention has good temperature resistance.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. An adhesive for sealing rings, characterized in that, By weight, it includes the following raw materials: 90-110 parts modified fluororubber, 4-5 parts vulcanizing agent, and 230-270 parts solvent.

2. The adhesive for sealing rings according to claim 1, characterized in that, The preparation method of the modified fluororubber includes the following steps: (1) Under nitrogen protection, p-phenylenediamine and 2-amino-isophthalaldehyde were added to DMF and stirred for 20-30 min. Then, a catalyst was added and the reaction was carried out at 130-140 °C for 40-50 h. The compound was obtained after post-treatment. (2) Add the compound obtained in step (1) along with fluororubber and dicyclohexylcarbodiimide into DMF and stir for 20-24 hours to obtain modified fluororubber.

3. The adhesive for sealing rings according to claim 2, characterized in that, The molar ratio of p-phenylenediamine to 2-aminoisophthalaldehyde is 1:(1-1.2).

4. The adhesive for sealing rings according to claim 2, characterized in that, The fluororubber is a liquid-terminated carboxyl fluororubber.

5. The adhesive for sealing rings according to claim 2, characterized in that, The mass ratio of the compound to fluororubber in step (2) is (0.3-0.7):

1.

6. The adhesive for sealing rings according to claim 1, characterized in that, The vulcanizing agent is a combination of triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

7. The adhesive for sealing rings according to claim 6, characterized in that, The mass ratio of the triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is (1.8-2.2):

1.

8. The adhesive for sealing rings according to claim 1, characterized in that, The solvent is methyl isobutyl ketone.

9. A method for preparing an adhesive for sealing rings according to any one of claims 1-8, characterized in that, Includes the following steps: Add the modified fluororubber to the solvent and soak it at room temperature for 7-8 days. Then add the vulcanizing agent and stir for 5-10 minutes. Let it stand for 25-35 minutes to obtain the product.

10. A method of applying the adhesive for sealing rings according to any one of claims 1-8 or the adhesive obtained by the preparation method according to claim 9, characterized in that, The process includes the following steps: Cut the vulcanized rubber strip into a circular cross-section, apply adhesive, and let it sit at room temperature for 50-70 minutes. Then, align the two adhesive-coated surfaces together and place them in a preheated mold. Vulcanize at 155-165℃ for 15-20 minutes.

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