Production method and application of a ternary ethylene-propylene sealing ring

Abstract

The application relates to a production method and application of a ternary ethylene-propylene sealing ring, and belongs to the technical field of rubber. The production method comprises foaming extrusion, cutting and welding fusion; the foaming extrusion process is that ternary ethylene-propylene material is extruded into shape through an extrusion die by a foaming process to obtain a ternary ethylene-propylene sealing strip; and the welding fusion process is that butt joints of ternary ethylene-propylene sealing strips with different lengths are welded and fused together by a hot vulcanization process. The ternary ethylene-propylene material is adopted, so that the corrosion of a humid and hot underground environment to products such as a box body is avoided. The foaming extrusion process is used for processing, the method of mold injection is avoided to produce sealing rings with specific lengths, the sealing strip produced by using a set of extrusion dies is prepared into sealing rings with different sizes through the cutting and welding method, and can be used for the sealing of box bodies with various sizes. The development cost is saved.

Description

Technical Field

[0001] This invention belongs to the field of rubber technology, and in particular relates to a method for producing and applying an EPDM sealing ring. Background Technology

[0002] Currently, the sealing and protective components for enclosures operating in underground, humid, and hot environments mainly use silicone rubber, nitrile rubber, polyurethane foam sealing rings, or silicone foam sealing rings. However, these materials all have certain shortcomings when used in high-protection scenarios. For example, silicone rubber and nitrile rubber are not resistant to acids and alkalis, polyurethane foam sealing rings are not resistant to high temperatures, and silicone foam sealing rings are prone to aging and corrosion.

[0003] These materials, when used for extended periods in the humid and hot underground environment, are prone to causing the sealing rings to fail. Furthermore, when the size of the protective rings on the sealed enclosure varies, molds of corresponding sizes must be made, resulting in high mold-making costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a production method and application of EPDM sealing rings, achieving low cost, short production cycle, and high protective performance when EPDM sealing rings are applied to enclosures of different sizes.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In one aspect, a method for producing a EPDM sealing ring includes: foaming extrusion, cutting, and welding fusion;

[0007] The raw materials used in the foaming extrusion step consist of the following components in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide vulcanizing agent, 25-35 parts carbon black reinforcing agent, 2 parts foaming agent, 1-2 parts sulfur, 1-2 parts accelerator, 1-2 parts surfactant, 15-25 parts paraffin oil, and 1.5-2.5 parts calcium oxide.

[0008] The foaming and extrusion process includes:

[0009] S1. Add EPDM rubber to a two-roll mill for plasticizing; then add reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide, and surfactant for mixing;

[0010] S2. Add sulfur to the rubber compound, pre-vulcanize, then add accelerator and foaming agent in the mixing mill and mix, then produce samples and sheets.

[0011] S3. Freely foam in an oven at a set temperature 1, then extrude the foamed finished sealing strip;

[0012] The welding fusion process involves welding the joints of EPDM sealing strips of different lengths together using a hot vulcanization process.

[0013] Optionally, the reinforcing carbon black is reinforcing carbon black N550.

[0014] Optionally, the foaming agent is an organic foaming agent AC.

[0015] Optionally, the accelerator includes one or more of accelerator M and accelerator TT.

[0016] Optionally, the surfactant is stearic acid (SA).

[0017] Optionally, during the foaming and extrusion process, the plasticizing temperature after adding EPDM rubber is 50°C.

[0018] Optionally, the mixing temperature after adding the corresponding amounts of reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide, and surfactant stearic acid is 50°C.

[0019] Optionally, the pre-vulcanization temperature after adding sulfur is 170°C.

[0020] Optionally, the temperature for free foaming in the oven is 175°C.

[0021] Secondly, the EPDM seal ring obtained using the above-mentioned production method for EPDM seal rings.

[0022] Thirdly, the application of the aforementioned EPDM sealing rings in the waterproof sealing of the enclosure.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. This invention uses EPDM material, fully utilizing its resistance to acid, alkali, salt water vapor corrosion, successfully avoiding corrosion of the enclosure and other products caused by the humid and hot underground environment. Furthermore, it employs a foaming extrusion process, avoiding the use of injection molding to produce sealing rings of specific lengths. Sealing strips produced using a single extrusion die are then cut and welded to create sealing rings of various sizes, enabling sealing of enclosures of multiple sizes. This saves development costs.

[0025] 2. This invention forms an internal independent pore structure through a foaming process. The pores are not interconnected, which effectively avoids the problem of unbalanced mechanical properties of the sealing surface caused by local damage to traditional sealing rings. This achieves reliable waterproof protection for the sealing ring and can be used for IP68 protection requirements. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0027] Figure 1 This is a schematic diagram of the overall structure in Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure at the butt joint corner of the sealing ring in Embodiment 1 of the present invention;

[0029] Figure 3 This is a cross-sectional schematic diagram of the sealing ring in Embodiment 1 of the present invention;

[0030] Figure 4 This is the present invention. Figure 3 A magnified view of a portion of the image;

[0031] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0032] Among them, 1. EPDM sealing strip; 2. Flat surface. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] A method for producing an EPDM sealing ring includes: foaming extrusion and welding fusion;

[0036] The raw materials used in the foaming extrusion step consist of the following components in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide vulcanizing agent, 25-35 parts carbon black reinforcing agent, 2 parts foaming agent, 1-2 parts sulfur, 1-2 parts accelerator, 1-2 parts surfactant, 15-25 parts paraffin oil, and 1.5-2.5 parts calcium oxide.

[0037] The foaming and extrusion process includes:

[0038] S1. Add EPDM rubber to a two-roll mill for plasticizing; then add reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide, and surfactant for mixing;

[0039] S2. Add sulfur to the rubber compound, pre-vulcanize, then add accelerator and foaming agent in the mixing mill and mix, then produce samples and sheets.

[0040] S3. Freely foam in an oven at a set temperature, then extrude the foamed product to obtain EPDM sealing strips;

[0041] The welding fusion process involves welding the joints of EPDM sealing strips of different lengths together using a hot vulcanization process.

[0042] Optionally, the grade of the EPDM raw material is 4067-1084, and the density is 0.65±0.05g / cm.

[0043] Optionally, the reinforcing carbon black is carbon black N550; it is a rubber carbon black suitable for natural rubber and various synthetic rubbers, easy to disperse, and has good reinforcing, elasticity and recovery properties.

[0044] Optionally, the foaming agent is an organic foaming agent AC; the components include azodicarbonamide, which is used to generate a large number of closed pore structures during the baking process.

[0045] Optionally, the accelerator includes one or more of accelerator M and accelerator TT; used to increase the reaction rate.

[0046] The components of accelerator M include: 2-mercaptobenzothiazole;

[0047] Accelerator TT, also known as accelerator TMTD, consists of: dimethyl disulfide carbonyl dimethylamine.

[0048] Optionally, the surfactant is stearic acid (SA), also known as octadecanoic acid, which is used together with the foaming agent to complete the foaming process and play an emulsifying role to adjust the size of the pore structure.

[0049] Optionally, during the foaming and extrusion process, the plasticizing temperature after adding EPDM rubber is 50°C.

[0050] Optionally, the mixing temperature after adding the corresponding amounts of reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide, and surfactant stearic acid is 50°C.

[0051] Optionally, the pre-vulcanization temperature after adding sulfur is 170°C.

[0052] Optionally, the temperature for free foaming in the oven is 175°C.

[0053] Optionally, the foamed EPDM sealing strip has a plane parallel to the extrusion direction.

[0054] Optionally, a EPDM sealing strip of a set length is cut, with the cut cross-section being: on a plane parallel to the extrusion direction, at a 45° angle to the extrusion direction.

[0055] Optionally, the cross sections of the EPDM sealing strips of the set length obtained by cutting are joined together and then welded together to form a 90-degree angle.

[0056] Through the above foaming process, an independent and closed pore structure can be formed inside the EPDM sealing strip. By adjusting the process parameters, the size and distribution of the pores can be adjusted, thereby regulating the material hardness and achieving better sealing performance.

[0057] The EPDM sealing ring obtained by the above-mentioned production method has a Shore hardness of A30 and a compression ratio of 40%.

[0058] Optionally, the EPDM sealing strip has an adhesive coating on a plane parallel to the extrusion direction.

[0059] Optionally, the adhesive used is 3M adhesive with a thickness of 0.1mm.

[0060] A EPDM sealing ring is obtained by the above-described method for producing EPDM sealing rings.

[0061] The above-mentioned EPDM sealing rings are used in the field of waterproof sealing of enclosures.

[0062] Optionally, the above applications include: applications in the field of waterproof sealing of electronic components; electronic components include: electronic components used in vehicles, communication equipment, medical instruments, industrial equipment, military equipment, aerospace equipment and / or underwater equipment.

[0063] Example 1

[0064] A method for producing an EPDM sealing ring includes: foaming extrusion and welding fusion;

[0065] The foaming and extrusion process is as follows: EPDM material is foamed and extruded using an extrusion die to obtain EPDM sealing strips;

[0066] 100 parts EPDM rubber, 5 parts zinc oxide vulcanizing agent, 30 parts carbon black N550 reinforcing agent, 2 parts organic foaming agent AC, 1.5 parts sulfur, 1.5 parts accelerator M, 0.5 parts accelerator TT, 2 parts stearic acid SA surfactant, 20 parts paraffin oil, and 2 parts calcium oxide.

[0067] The foaming extrusion process is as follows: EPDM rubber is added to a two-roll mill and plasticized at 50°C for 5 minutes. Then, the corresponding proportions of carbon black, paraffin oil, calcium oxide, zinc oxide, and stearic acid are added and mixed at 50°C for 10 minutes. Next, the corresponding proportions of sulfur are added to the rubber compound and pre-vulcanized at 170°C for 10 minutes. Then, the vulcanization system and foaming agent are added to a mixing mill and mixed for 10 minutes. Samples are then produced and sheets are extruded. Finally, the mixture is freely foamed in an oven at a set temperature of 175°C for 18 minutes, and the foamed sealing ring is extruded.

[0068] The welding fusion process involves welding the joints of EPDM sealing strips of different lengths together using a hot vulcanization process.

[0069] The grade of the EPDM raw material is 4067-1084, and the density is 0.65±0.05g / cm³.

[0070] During the foaming process, an independent and closed pore structure is formed inside the EPDM sealing strip.

[0071] The Shore hardness of the EPDM sealing strip is A30.

[0072] like Figure 3 As shown, the foamed EPDM sealing strip 1 has a plane 2 parallel to the extrusion direction, and adhesive is applied to this plane.

[0073] Optionally, the adhesive used is 3M adhesive with a thickness of 0.1mm.

[0074] like Figure 2 As shown, after foaming and extrusion, a EPDM sealing strip 1 of a set length is cut. The cut section is: on a plane parallel to the extrusion direction, at a 45° angle to the extrusion direction.

[0075] like Figure 1 As shown, the cross sections of the EPDM sealing strip 1, which are cut to a set length, are joined together and then welded together to form a 90-degree angle.

[0076] This embodiment utilizes a foam extrusion process to avoid using injection molding to produce sealing rings of specific lengths. It uses only one extrusion die to continuously produce sealing strips. The cross-sectional shape of the sealing strip perpendicular to the extrusion direction is as follows: Figure 4 As shown, it includes a plane 2 and an arc surface at a set distance from the plane. The plane 2 and the arc surface are connected by a vertical surface perpendicular to the plane.

[0077] Sealing rings of different sizes can be manufactured by cutting and welding, which can be used for sealing various sizes of boxes, saving development costs.

[0078] The EPDM sealing ring prepared in this embodiment has a compression of 40%, which can achieve reliable waterproof protection and meet IP68 protection requirements.

[0079] When the compression is too large, the permanent deformation and rebound performance of the sealing ring is poor. When the sealed enclosure is opened, the sealing ring cannot rebound quickly, and the pores inside the sealing ring are easily compressed and deformed into an open structure, resulting in permanent deformation and inability to rebound. When the compression is too small, the compression deformation of the sealing ring is too small, causing the enclosure it protects to fail to meet the IP68 protection requirements.

[0080] The above applications include: applications in the field of waterproof sealing of electronic components; electronic components include: electronic components used in vehicles, communication equipment, medical instruments, industrial equipment, military equipment, aerospace equipment and / or underwater equipment.

[0081] The above applications include, but are not limited to, water level detectors, various gas sensors, data collectors, water meters, electricity meters, and various industrial switching and communication equipment installed in damp locations, water accumulation locations, and sewage treatment equipment in tunnels. Products protected by this sealing ring have demonstrated excellent sealing performance even when operating in water depths of 5 meters and containing polluted water containing hot steam, acid, alkali, salt, etc.

[0082] Comparative Example

[0083] The EPDM sealing ring obtained by injection molding is composed of the following raw materials in parts by weight: 80 parts EPDM 3280, 20 parts polypropylene K912, 3 parts active zinc oxide, 3 parts light magnesium oxide, 0.5 parts stearic acid, 0.25 parts antioxidant 1010, 0.5 parts antioxidant 168, 30 parts paraffin wax, 30 parts carbon black N660, 50 parts calcium silicate CSH-21, 1.2 parts naphthenic oil, 1.2 parts sulfur, 1.2 parts accelerator M, 1.2 parts accelerator TMTD, and 1.2 parts accelerator CZ.

[0084] EPDM and polypropylene blended thermoplastic elastomers are usually made in one step by compression molding and vulcanization. They are difficult to reheat and reshape, so they cannot be joined after extrusion molding. Using ordinary adhesives will result in the inability to guarantee a waterproof seal at the joint. Therefore, a sealing ring can only be formed in one piece by molding.

[0085] On the one hand, the proportional method requires a dedicated set of molds to produce different types of boxes, which increases mold costs when multiple boxes are used.

[0086] On the other hand, the sealing ring formed by the proportional molding method does not involve the participation of foaming agent in the reaction. After thermoforming, there are no air bubbles inside. Compared with EPDM foam sealing ring, the internal structure is dense and solid, so the elasticity is poor, the hardness is high, and the sealing and protection performance of the box is weak.

[0087] The performance test results of Example 1 and the comparative example are shown in Table 1.

[0088] Table 1

[0089]

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing EPDM sealing rings, Its features are, This includes: foaming extrusion, cutting, and welding fusion; The raw materials used in the foaming extrusion step consist of the following components in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide vulcanizing agent, 25-35 parts carbon black reinforcing agent, 2 parts foaming agent, 1-2 parts sulfur, 1-2 parts accelerator, 1-2 parts surfactant, 15-25 parts paraffin oil, and 1.5-2.5 parts calcium oxide. The foaming and extrusion process includes: S1. Add EPDM rubber to a two-roll mill for plasticizing; then add reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide, and surfactant for mixing; S2. Add sulfur to the rubber compound, pre-vulcanize, then add accelerator and foaming agent in a mixing mill and mix, then produce samples and sheets. The pre-vulcanization temperature after adding sulfur is 170℃, and the time is 10 minutes; S3. Allow the foam to expand freely in a baking oven at a set temperature, and then extrude the foamed finished sealing strip; The temperature for free foaming in the baking oven is 175℃, and the time is 18 minutes. The welding process involves fusing the butt joints of EPDM sealing strips of different lengths together using a hot vulcanization process; the Shore hardness of the EPDM sealing strip is A30, and the compression of the EPDM sealing ring is 40%. The foaming agent is an organic foaming agent AC.

2. The method for producing the EPDM sealing ring as described in claim 1, characterized in that, The grade of the EPDM raw material is 4067-1084, and its density is 0.65±0.05 g / cm³. 3 .

3. The method for producing the EPDM sealing ring as described in claim 1, characterized in that, The reinforcing carbon black is reinforcing carbon black N550.

4. The method for producing the EPDM sealing ring as described in claim 1, characterized in that, The accelerator includes one or more of accelerator M and accelerator TT.

5. The method for producing the EPDM sealing ring as described in claim 1, characterized in that, The surfactant is stearic acid (SA).

6. The method for producing a EPDM sealing ring as described in claim 1, characterized in that, During the foaming and extrusion process, the plasticizing temperature after adding EPDM rubber is 50℃ and the time is 5 minutes.

7. The method for producing a EPDM sealing ring as described in claim 1, characterized in that, The mixing temperature after adding the corresponding amounts of reinforcing agent carbon black, paraffin oil, calcium oxide, vulcanizing agent zinc oxide and surfactant stearic acid is 50°C and the mixing time is 10 minutes.

8. The method for producing a EPDM sealing ring as described in claim 1, characterized in that, The foamed EPDM sealing strip has a plane parallel to the extrusion direction.

9. The method for producing a EPDM sealing ring as described in claim 1, characterized in that, Cut EPDM sealing strips to a set length. The cut section is on a plane parallel to the extrusion direction, at a 45° angle to the extrusion direction.

10. The method for producing a EPDM sealing ring as described in claim 1, characterized in that, After the cross sections of the EPDM sealing strips of the set length are cut together, they are welded together to form a 90-degree angle.

11. A EPDM sealing ring obtained by the production method of any one of claims 1-10, characterized in that, EPDM sealing strips have a plane parallel to the extrusion direction, and adhesive is applied to said plane.

12. The EPDM sealing ring as described in claim 11, characterized in that, The adhesive used is 3M adhesive, with a thickness of 0.1mm.

13. A method for producing a EPDM sealing ring as described in any one of claims 1-10 and / or the application of the EPDM sealing ring as described in any one of claims 11-12 in the field of waterproof sealing of enclosures, characterized in that, include: Applications in the field of waterproof sealing of electronic components.

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