Plate heat exchanger sealing gasket and production method thereof

Abstract

The invention discloses a plate heat exchanger sealing gasket and a production method thereof, and belongs to the technical field of high-molecular compound compositions. The sealing gasket is prepared from the following raw materials in parts by weight: 100 parts of mixed rubber, 65-75 parts of filler, 2-3 parts of a coupling agent, 30-35 parts of acrylic resin, 15-22 parts of a plasticizer and 3-4 parts of a vulcanization accelerator, the vulcanization accelerator is prepared from bis (tert-butylperoxy isopropyl) benzene, tetramethyl thiuram sulfide and dibenzothiazyl disulfide. According to the plate heat exchanger sealing gasket and the production method thereof, the internal structure of the sealing gasket is improved through the combined action of the rubber, the resin, the dolomite powder, the filler and various auxiliaries, the mechanical strength of the sealing gasket is improved, the compression set of the sealing gasket is reduced, and the sealing gasket is stable in form and high in integrity; and the sealing performance between the sealing gasket and the plate sheet is ensured.

Description

Technical Field

[0001] This invention relates to a plate heat exchanger sealing gasket and its manufacturing method, belonging to the technical field of polymer compound compositions. Background Technology

[0002] Plate heat exchangers are widely used in industries such as chemical, petroleum, power, and pharmaceutical. Their main components are clamping screws, plates, and gaskets. A gasket is placed between every two adjacent plates. After the plates are clamped together by the clamping screws, a gap is formed between the adjacent plates and the gaskets to allow for media flow. The gaskets prevent media leakage between the plates, reduce heat loss, and maintain the appropriate gap size between the plates.

[0003] During operation, the gaskets in a plate heat exchanger are constantly compressed; and the medium flowing between the plates comes into direct contact with the gaskets. Prolonged pressure and exposure to high temperatures and chemical media (oil, acid) can cause the gaskets to age, crack, or harden, affecting the heat exchanger's efficiency and even leading to leaks. Furthermore, the gaskets expand at high temperatures and contract at low temperatures, exhibiting a reciprocating expansion and contraction characteristic. Additionally, during operation, the heat exchanger requires shutdown for cleaning or maintenance. After cleaning and maintenance, when the gaskets are reinstalled and the plates are compressed, the gaskets' resilience and compressibility can cause them to fail to form an effective seal between the plates at the preset compression gap. In such cases, replacing the gaskets or reducing the gap between the plates is necessary; the former increases operating costs, while the latter affects heat exchange efficiency.

[0004] Plate heat exchanger gaskets are typically made from rubber raw materials and additives such as accelerators, plasticizers, antioxidants, vulcanizing agents, and fillers. The gasket manufacturing process involves multiple steps, including mixing, extrusion, calendering, and vulcanization. During processing, the various additives and rubber raw materials undergo complex physical and chemical changes, determining the overall performance of the gasket. To maintain the required sealing preload between the gasket and the plate under different temperature and pressure conditions, the gasket needs to possess good stress relaxation rate and compression set properties. Currently, some publicly available rubber gasket production formulas and processes primarily focus on the gasket's high-temperature resistance and corrosion resistance, while neglecting the aforementioned characteristics. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a plate heat exchanger gasket and its manufacturing method, which improves the mechanical strength of the gasket, reduces the compression permanent deformation and stress relaxation rate of the gasket, and makes the gasket have a stable appearance and strong integrity.

[0006] The present invention achieves the above objectives by adopting the following technical solutions: On one hand, the present invention provides a plate heat exchanger sealing gasket, made from the following raw materials in parts by weight: Mixed rubber 100 parts, filler 65-75 parts, coupling agent 2-3 parts, acrylic resin 30-35 parts, plasticizer 15-22 parts, vulcanization accelerator 3-4 parts; The mixed rubber is composed of hydrogenated nitrile butadiene rubber and ethylene propylene diene monomer rubber; The filler is composed of semi-reinforcing carbon black and dolomite powder in a weight ratio of (50-60):(15-18); The coupling agent is composed of isopropyl dioleoyl oxy (dioctyl phosphate oxy) titanate and / or isopropyl triisostearoyl titanate; The plasticizer is composed of paraffin oil and dioctyl adipate in a weight ratio of (10-15):(5-7); The vulcanization accelerator is composed of bis-tert-butylperoxyisopropylbenzene, tetramethylthiuram sulfide, and dibenzothiazole disulfide.

[0007] Preferably, the weight ratio of hydrogenated nitrile rubber to ethylene propylene diene monomer (EPDM) rubber is (25-35):(60-70).

[0008] Preferably, the weight ratio of bis-tert-butylperoxyisopropylbenzene, tetramethylthiuram sulfide, and dibenzothiazole disulfide is (0.7-1):(1.5-2.2):0.8.

[0009] Preferably, the weight ratio of isopropyl dioleoyl oxy (dioctyl phosphate oxy) titanate to triisostearoyl titanate is (1.3-1.7):(0.7-1.3).

[0010] Optionally, the mass fraction of acrylonitrile in the hydrogenated nitrile rubber is 35-43%.

[0011] On the other hand, the present invention also provides a manufacturing process for the above-mentioned plate heat exchanger gasket, comprising the following steps: Step S1: Mix paraffin oil with coupling agent, dolomite powder and semi-reinforcing carbon black to prepare a premix; Step S2: Add the mixed rubber and acrylic resin into a mixer and mix them thoroughly. Step S3: Put the premix obtained in step S1 into the internal mixer and continue mixing and internal mixing; Step S4: After discharging and cooling the intensively mixed mixture obtained in step S3, put it into a two-roll mill, add plasticizer and vulcanization accelerator to the intensively mixed mixture, and knead to obtain the compound rubber. Step S5: Feed the rubber compound into a cold feed extruder and extrude it to obtain strips of rubber compound. Let it rest. Step S6: Place the mixed rubber strips in a flat vulcanizing machine, and mold and vulcanize them to obtain the plate heat exchanger gasket.

[0012] Preferably, step S1 specifically involves: mixing paraffin oil with a coupling agent in a molten state to form a mixture, spraying the mixture onto dolomite powder under high-speed stirring, continuing to stir for 3-4 minutes, then adding semi-reinforcing carbon black and continuing to stir and mix evenly to form a premix.

[0013] Preferably, the mixing temperature in steps S2 and S3 does not exceed 150°C, the rotation speed is 34-38 r / min, the mixing time in step S2 is 8-10 min, and the mixing time in step S3 is 10-12 min.

[0014] Preferably, the temperature during the initial milling process in step S4 is not higher than 80°C, and the time is 10-12 minutes.

[0015] Preferably, in step S6, the molding and vulcanization temperature is 155-170℃, and the time is 13-18min.

[0016] The beneficial effects of this application include, but are not limited to: The plate heat exchanger gasket and its manufacturing method provided by this invention utilize the combined effects of rubber, resin, dolomite powder, fillers, and various additives to improve the internal structure of the gasket, thereby increasing its mechanical strength, reducing its compression set and stress relaxation rate, and ensuring a stable appearance and strong integrity, thus guaranteeing the sealing performance between the gasket and the plate. During production, dolomite powder is first processed to prepare a premix, which is then mixed with rubber, resin, and other components, improving the bonding performance between the dolomite powder and these components. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of a plate heat exchanger gasket, with tongue-shaped structures distributed around its perimeter. Detailed Implementation

[0018] The present invention will be further described in detail below. However, it should be noted that the following specific embodiments are merely exemplary examples of the invention, and the scope of protection of the invention is not limited thereto. The scope of protection of the invention is defined only by the claims. It will be apparent to those skilled in the art that various other modifications and substitutions can be made to the embodiments of the invention within the scope of protection defined by the claims, and the same technical effects can still be achieved, thus achieving the ultimate technical objective of the invention.

[0019] In this invention, all numerical ranges include end values ​​and may include new numerical ranges obtained by arbitrarily combining the upper and lower limits of the disclosed ranges.

[0020] Unless otherwise specified, all raw materials in this manual were purchased through commercial channels. Specific information on some raw materials is described below.

[0021] Hydrogenated nitrile butadiene rubber, Qilu Petrochemical; Ethylene propylene diene monomer (DCPD monomer), PetroChina Jilin Petrochemical; Semi-reinforcing carbon black, 150-200 mesh; Dolomite powder, 130-220 mesh, Meng County, Yangquan City, Shanxi Province; Isopropyl dioleoyl oxy(dioctyl phosphate oxy) titanate (ZJ-311), Guangzhou Zhongjie Chemical Technology Co., Ltd.; Triisostearoyl titanate isopropyl ester (TTS), Hubei Fangde New Materials Co., Ltd.; Paraffin oil, Zibo Taichang Lubricating Oil Co., Ltd.; Dioctyl adipate (DOA), Shandong Yousuo Chemical Technology Co., Ltd.; Di-tert-butylperoxyisopropylbenzene, Hubei Kemaidi Chemical Co., Ltd.; Tetramethylthiuram sulfide, Zhonghe Chemical (Shandong) Co., Ltd.; Dibenzothiazole disulfide, Shandong Qiangsen Chemical Co., Ltd.

[0022] I. The following will provide a detailed description of the plate heat exchanger gasket and its production method provided by the present invention through specific embodiments and comparative examples.

[0023] Example 1: The raw materials used in the plate heat exchanger sealing gasket provided in this embodiment are shown in Table 1.

[0024]

[0025] The production method of the plate heat exchanger gasket provided in this embodiment is as follows: Step S1: Melt the paraffin oil and mix it with the coupling agent to make a mixture. Dilute the coupling agent. Spray the mixture into dolomite powder under high-speed stirring at 1300 rpm and continue stirring for 4 minutes to allow the coupling agent to interact with the dolomite powder and form active sites on the surface of the dolomite powder. Then add semi-reinforcing carbon black and continue stirring to mix evenly to make a premix. Step S2: Add the mixed rubber and acrylic resin into a mixer and mix them at a speed of 34-38 r / min, a mixing temperature of 130-140℃, and a time of 8 min. Step S3: Put the premix obtained in step S1 into the internal mixer and continue mixing and kneading at a temperature of 130°C for 12 minutes. Step S4: After the intensively mixed mixture obtained in step S3 is discharged and cooled, it is fed into a two-roll mill. Plasticizer and vulcanization accelerator are added to the intensively mixed mixture, and the mixture is kneaded at a temperature not higher than 80°C for 12 minutes to obtain the compound rubber. Step S5: Feed the rubber compound into a cold feed extruder and extrude it to obtain strips of rubber compound. Let it rest. Step S6: Cut the mixed rubber strip according to the shape and size of the sealing gasket mold cavity in the flat vulcanizing machine. Place the cut mixed rubber strip in the mold cavity of the flat vulcanizing machine and mold and vulcanize at a temperature of 155-170℃ for 15 minutes. This allows the rubber, resin and other raw materials to cross-link with each other under the action of various additives, forming a plate heat exchanger sealing gasket. Then place the plate heat exchanger sealing gasket in an oven at 150℃ for 2 hours.

[0026] Example 2: The raw materials used in the plate heat exchanger sealing gasket provided in this embodiment are shown in Table 2.

[0027]

[0028] The production method of the plate heat exchanger gasket provided in this embodiment is as follows: Step S1: Melt the paraffin oil and mix it with the coupling agent to make a mixture. Spray the mixture onto the dolomite powder under high-speed stirring at 1400 rpm and continue stirring for 4 minutes. Then add the semi-reinforcing carbon black and continue stirring to mix evenly to make a premix. Step S2: Add the mixed rubber and acrylic resin into the internal mixer and mix them at a speed of 35 r / min, a mixing temperature of 135℃, and a time of 10 min. Step S3: Put the premix obtained in step S1 into the internal mixer and continue mixing and internal mixing at a temperature of 130°C for 10 minutes. Step S4: After the intensively mixed mixture obtained in step S3 is discharged and cooled, it is fed into a two-roll mill. Plasticizer and vulcanization accelerator are added to the intensively mixed mixture, and the mixture is kneaded at a temperature not higher than 80°C for 12 minutes to obtain the compound rubber. Step S5: Feed the rubber compound into a cold feed extruder and extrude it to obtain strips of rubber compound. Let it rest. Step S6: Cut the mixed rubber strip according to the shape and size of the sealing gasket mold cavity in the flat vulcanizing machine. Place the cut mixed rubber strip in the mold cavity of the flat vulcanizing machine, mold and vulcanize at 160℃ for 14 minutes to form the plate heat exchanger sealing gasket. Then place the plate heat exchanger sealing gasket in an oven at 150℃ for 2 hours.

[0029] The final production step of the plate heat exchanger gasket involves filling the mold cavity of a flat vulcanizing machine with appropriately sized compounded rubber strips. The temperature and pressure provided by the machine melt the strips, allowing them to fully fuse together at the joints and solidify. The degree of fusion at the joints is closely related to the Mooney viscosity of the rubber compound, the vulcanization rate and time, and the crosslinking density.

[0030] Example 3: The raw materials used in the plate heat exchanger sealing gasket provided in this embodiment are shown in Table 3.

[0031]

[0032] The production method of the plate heat exchanger gasket provided in this embodiment is the same as that in Embodiment 1.

[0033] Example 4: The raw materials used in the plate heat exchanger sealing gasket provided in this embodiment are shown in Table 4.

[0034]

[0035] The production method of the plate heat exchanger gasket provided in this embodiment is the same as that in Embodiment 2.

[0036] In the above production methods, the refining of the rubber compound in the open mill can be carried out using conventional methods. This typically involves adding plasticizers and vulcanization accelerators after the rubber compound has wrapped around the rollers, followed by steps such as cutting, thin-passing, forming triangular wraps, and sheeting. Cold-feed extruders are equipment used in the rubber industry, and can be used to extrude rubber compounds using conventional parameters.

[0037] Comparative Example 1: The difference between this comparative example and Example 1 is that the acrylic resin is replaced with tert-butylphenol resin and the coupling agent is replaced with titanate coupling agent HY-311.

[0038] Comparative Example 2: The difference between this comparative example and Example 1 is that steps S1-S3 in Example 1 are replaced with "mixing and mixing the mixed rubber, acrylic resin, paraffin oil, and coupling agent in a mixer at a speed of 34-38 r / min, a mixing temperature of 130-140℃, and a time of 15 min".

[0039] Comparative Example 3: The difference between this comparative example and Example 2 is that the coupling agent used is 5 parts of silane coupling agent KH-550.

[0040] Comparative Example 4: The difference between this comparative example and Example 1 is that the vulcanization accelerator is replaced with 3 parts zinc oxide, 2 parts stearic acid, and 1 part sulfur.

[0041] II. Performance Analysis of Plate Heat Exchanger Gaskets Produced in Each Embodiment and Comparative Example Test standards: Shore A hardness GB / T531; tensile properties: GB / T528-2009; compression set GB / T7759-96 (24h, 200℃).

[0042] Stress relaxation rate: Thermal cycling test, the temperature is raised to 160℃ in 15 min, the internal pressure is increased to 1.0 MPa, and maintained for 20 min; the temperature is lowered to 25℃ in 30 min, the internal pressure is increased to 1.5 MPa, and maintained for 20 min, and the cycle test is repeated 7.0 times.

[0043] The test results are shown in Table 5.

[0044]

[0045] Comparison shows that the plate heat exchanger gaskets provided in the embodiments of the present invention exhibit excellent performance in terms of hardness, tensile strength, compression set, stress relaxation rate, and flatness. The gaskets produced in the comparative examples, however, suffer from increased compression set, inadequate flattening, and a tendency for the tongue portion to break during demolding.

[0046] Furthermore, practical application in the field has proven that the plate heat exchanger gasket provided by this invention has good corrosion resistance to most acids and organic solvents; and the thinning rate of the gasket at the fluid inlet and outlet meets the requirements.

[0047] The above specific embodiments should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, any alternative improvements or modifications made to the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0048] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A plate heat exchanger gasket, characterized in that: Made from the following raw materials in parts by weight: Mixed rubber 100 parts, filler 65-75 parts, coupling agent 2-3 parts, acrylic resin 30-35 parts, plasticizer 15-22 parts, vulcanization accelerator 3-4 parts; The mixed rubber consists of hydrogenated nitrile rubber and EPDM rubber; The filler is composed of semi-reinforcing carbon black and dolomite powder in a weight ratio of (50-60):(15-18); The coupling agent is composed of isopropyl dioleyloxy (dioctylphosphoacyloxy) titanate and / or triisostearoyl isopropyl titanate; The plasticizer is composed of paraffin oil and dioctyl adipate in a weight ratio of (10-15):(5-7); The vulcanization accelerator consists of di-tert-butyl peroxyisopropylbenzene, tetramethylthiuram sulfide and dibenzothiazole disulfide.

2. The plate heat exchanger sealing gasket according to claim 1, characterized in that: The weight ratio of hydrogenated nitrile rubber and EPDM rubber is (25-35):(60-70).

3. The plate heat exchanger sealing gasket according to claim 1, characterized in that: The weight ratio of di-tert-butyl peroxyisopropylbenzene, tetramethylthiuram sulfide and dibenzothiazyl disulfide is (0.7-1):(1.5-2.2):0.

8.

4. The plate heat exchanger sealing gasket according to claim 1, characterized in that: The weight ratio of isopropyl dioleyl (dioctyl phosphate) titanate to isopropyl triisostearoyl titanate is (1.3-1.7): (0.7-1.3).

5. The plate heat exchanger sealing gasket according to claim 1, characterized in that: The mass fraction of acrylonitrile in hydrogenated nitrile rubber is 35-43%.

6. A production process for a plate heat exchanger sealing gasket according to any one of claims 1 to 5, characterized in that: The steps include: Step S1: mixing paraffin oil with a coupling agent, dolomite powder, and semi-reinforced carbon black to prepare a premix; Step S2: putting the mixed rubber and acrylic resin into an internal mixer for mixing and kneading; Step S3: putting the premix obtained in step S1 into an internal mixer and continuing mixing and kneading; Step S4: discharging the banburying mixture obtained in step S3, cooling it, and putting it into an open mill, adding a plasticizer and a vulcanization accelerator into the banburying mixture, and refining it to obtain a rubber mix; Step S5: putting the mixed rubber into a cold feed extruder, extruding a mixed rubber strip to obtain a strip, and then leaving it for storage; Step S6: placing the mixed rubber strip on a flat vulcanizer, molding and vulcanizing to obtain a plate heat exchanger sealing gasket.

7. The production process according to claim 6, characterized in that: Step S1 is specifically as follows: paraffin oil is mixed with a coupling agent in a melted state to form a mixed liquid, the mixed liquid is sprayed on dolomite powder in a high-speed stirring state, stirring is continued for 3-4 minutes, and then semi-reinforced carbon black is added and stirred and mixed evenly to form a premix.

8. The production process according to claim 6, characterized in that: The banburying temperatures in steps S2 and S3 are both no more than 150° C., the rotating speeds are both 34-38 r / min, the banburying time in step S2 is 8-10 min, and the banburying time in step S3 is 10-12 min.

9. The production process according to claim 6, characterized in that: The temperature during the initial refining in step S4 is not higher than 80° C. and the refining time is 10-12 minutes.

10. The production process according to claim 6, characterized in that: In step S6, the molding and vulcanization temperature is 155-170° C., and the time is 13-18 minutes.

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