CN-122008663-A - Composite sealing material for electrolytic tank and preparation method

CN122008663ACN 122008663 ACN122008663 ACN 122008663ACN-122008663-A

Abstract

The invention relates to the technical field of electrolytic tank sealing materials, in particular to an electrolytic tank composite sealing material and a preparation method thereof. The porous polytetrafluoroethylene composite electrolyte membrane comprises an impermeable layer, a composite matrix layer and an interface transition layer, wherein the impermeable layer is a microporous polytetrafluoroethylene layer, the microporous polytetrafluoroethylene layer is provided with a through hole structure, the interface transition layer is a fluorine-containing siloxane network layer, the composite matrix layer comprises an elastomer phase, a sheet-shaped insulating heat-conducting filler and a layered ion capturing filler, the surface of the sheet-shaped insulating heat-conducting filler is provided with a fluorosilane treatment layer, and the surface of the layered ion capturing filler is provided with a fluorine-containing organosilane treatment layer.

Inventors

WANG ZHANYANG
MA ZHEN
WANG WEI
ZHANG XUEGUANG
WANG KEXIN

Assignees

辽宁瑞麟氢能科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The composite sealing material for the electrolytic tank is characterized by comprising an impermeable layer, a composite matrix layer and an interface transition layer arranged between the impermeable layer and the composite matrix layer; The impermeable layer is a microporous polytetrafluoroethylene layer, and the microporous polytetrafluoroethylene layer is provided with a through hole structure; the interface transition layer is a fluorine-containing siloxane network layer, the fluorine-containing siloxane network layer is formed by hydrolytic condensation of fluorine-containing alkyl trialkoxysilane and epoxy trialkoxysilane, and the fluorine-containing siloxane network layer permeates into through holes of the microporous polytetrafluoroethylene layer to form a mechanical embedding structure; the composite matrix layer comprises an elastomer phase, a flaky insulating heat-conducting filler and a lamellar ion capturing filler, wherein the surface of the flaky insulating heat-conducting filler is provided with a fluorosilane treatment layer, and the surface of the lamellar ion capturing filler is provided with a fluorine-containing organosilane treatment layer; The layered ion capturing filler is distributed in the thickness direction gradient in the composite matrix layer, and the mass fraction of the layered ion capturing filler is higher than the mass fraction of the composite matrix layer in the rest thickness range of the composite matrix layer within the thickness range of 0-0.30 mm taking the surface of the composite matrix layer, which is close to the interface transition layer, as a starting surface.
2. The electrolytic cell composite sealing material according to claim 1, wherein the average pore diameter of the microporous polytetrafluoroethylene layer is 0.05 to 5 micrometers, and the penetration depth of the fluorine-containing siloxane network layer into the microporous polytetrafluoroethylene layer is 5 to 120 micrometers.
3. The electrolytic tank composite sealing material according to claim 1, wherein the elastomer phase is a dual-phase structure formed by dynamic vulcanization, the dual-phase structure comprises an ethylene propylene rubber phase and a fluorosilicone rubber phase, wherein the ethylene propylene rubber phase is a continuous phase, the fluorosilicone rubber phase is a dispersed phase, and the volume fraction of the fluorosilicone rubber phase is 10% -45%.
4. The electrolytic cell composite sealing material according to claim 1, wherein the layered ion capturing filler is a complex of a layered double hydroxide and a fluorine-containing anion exchange resin, and the layered double hydroxide and the fluorine-containing anion exchange resin exist in the thickness range of 0-0.30 mm in the form of composite particles.
5. The electrolytic tank composite sealing material according to claim 1, wherein the flaky insulating heat conducting filler is flaky boron nitride, the flaky boron nitride is distributed in an oriented manner in the composite matrix layer, and an included angle between the normal line of the flaky boron nitride and the thickness direction of the electrolytic tank composite sealing material is 0-30 degrees.
6. The electrolytic cell composite sealing material according to claim 1, wherein the composite substrate layer further comprises a reactive ion-pair crosslinking system comprising a quaternary ammonium salt-based polymer and a sulfonate-based polymer, and the reactive ion-pair crosslinking system and a peroxide crosslinking system together comprise a composite crosslinking structure.
7. The electrolytic cell composite sealing material according to claim 1, wherein the electrolytic cell composite sealing material is a frame type sealing gasket, the frame type sealing gasket is integrally formed with flange sealing ribs along the circumferential direction, the flange sealing ribs are formed by the composite substrate layer, and the impermeable layer continuously covers the top surface and the inner side surface of the flange sealing ribs.
8. A method for preparing the composite sealing material for an electrolytic cell according to any one of claims 1 to 7, comprising: s1, providing a microporous polytetrafluoroethylene layer as an impermeable layer, and performing plasma surface activation on the impermeable layer to form an activated surface; s2, preparing a fluorine-containing siloxane network precursor sol, wherein the fluorine-containing siloxane network precursor sol comprises fluorine-containing alkyl trialkoxysilane and epoxy trialkoxysilane; S3, applying the fluorine-containing siloxane network precursor sol to the activated surface and performing hydrolytic condensation to form an interface transition layer on the surface of the impermeable layer in situ, and enabling the interface transition layer to permeate into the through holes of the impermeable layer in the forming process; s4, preparing a composite matrix layer rubber compound, wherein the composite matrix layer rubber compound at least comprises an elastomer phase, a flaky insulating heat-conducting filler with a fluorosilane treatment layer on the surface and a lamellar ion capturing filler with a fluorosilane treatment layer on the surface; S5, preparing an enrichment film close to one side of the interface transition layer and a matrix film far away from one side of the interface transition layer, wherein the mass fraction of the layered ion capturing filler in the enrichment film is higher than that of the layered ion capturing filler in the matrix film; And S6, carrying out compression heating forming on the lamination body, and crosslinking and curing the composite matrix layer to obtain the electrolytic cell composite sealing material.
9. The method according to claim 8, wherein the surface activation of the plasma in step S1 includes a process condition of 100 to 800 watts for a process time of 5 to 180 seconds, and the working gas of the plasma includes a mixed gas of argon and oxygen.
10. The method of claim 8, wherein the fluorosilicone network precursor sol in step S2 further comprises a vinylsilane and a silylsilane, and wherein the addition reaction of vinyl groups and silylhydrogen groups occurs simultaneously during the hydrolytic condensation in step S3.

Description

Composite sealing material for electrolytic tank and preparation method Technical Field The invention relates to the technical field of electrolytic tank sealing materials, in particular to an electrolytic tank composite sealing material and a preparation method thereof. Background When the electrolytic tank operates in an alkaline or salt-containing electrolyte environment, the sealing part needs to form effective barrier to the electrolyte and keep a stable sealing state under the conditions of assembly compaction, temperature change, medium infiltration and the like. In addition to the dielectric resistance of the bulk material, the bond stability of the interface between the structural layers (e.g., barrier layer and elastomeric carrier layer) of the seal also affects the risk of leakage during long-term use. In the prior art, reinforced composite materials have been proposed that combine porous or expanded polytetrafluoroethylene structures with elastomeric materials. For example, publication number US20030211264A1 discloses ePTFE reinforced elastomer composites that are brought into a "substantially non-permeable" state in at least a partial region by impregnating an elastomer emulsion into the pores of the ePTFE and can be used to form media resistant elastomer composites (e.g., pump tubing, etc.). In addition, in the lamination bonding of a fluoropolymer substrate and silicone rubber, there is also a proposal to improve the adhesive strength by surface activation and introduction of a silane coupling agent. For example, publication No. EP2074188A1 discloses that a plastic or Polytetrafluoroethylene (PTFE) substrate/fluoropolymer substrate is subjected to plasma treatment to activate surface functional groups, and is coated with a liquid silicone rubber composition containing a silane coupling agent on its surface and then cured to obtain a laminated film structure and to improve interlayer bonding strength. Furthermore, from a material system perspective, publication number US6447918B1 also discloses interpenetrating polymer network layer structures comprising PTFE and cured silicone elastomers for obtaining specific surface layer properties. However, for the sealing conditions of long-term infiltration and loading of the electrolyte in the electrolytic tank, the above-mentioned routes, while respectively involving the technical points of "porous PTFE and elastomer composite", "surface activation+silane promotion bonding", "PTFE/siloxane network system", etc., may still have problems in some cases that when the interface bonding between the impermeable layer and the composite matrix layer is not stable enough, micro defects at the interface may develop into migration channels extending along the interface between layers under the action of long-term medium, thereby increasing the risk of electrolyte infiltration along the interface and causing sealing failure. US20030211264A1 focuses on achieving low permeability characteristics of the composite material by infiltration filling, and does not explicitly disclose construction of a controlled interface transition structure in porous PTFE through-holes for cell sealing interfaces, whereas EP2074188A1 discloses coating a silane-containing liquid silicone rubber after plasma treatment to improve lamination bonding, but focuses on improving bonding strength of laminated film structures, and does not give specific structural interface schemes for inhibition of interface migration channels under cell conditions. Therefore, a major technical problem to be solved in the prior art is how to enhance the interface bonding and the interface blocking stability between the polytetrafluoroethylene impermeable layer and the elastomer composite matrix layer under the long-term action of the electrolyte of the electrolytic bath, so as to inhibit the leakage risk caused by the migration of the electrolyte/ions along the interface. Disclosure of Invention In order to overcome the technical defects, the invention aims to provide the composite sealing material for the electrolytic tank and the preparation method thereof, and the invention forms mechanical embedding by constructing a fluorine-containing siloxane network interface transition layer which penetrates through holes in situ between a microporous polytetrafluoroethylene impermeable layer and a composite matrix layer, and meanwhile, the layered ion capturing filler is arranged on the near-interface side of the composite matrix layer and distributed in a gradient manner in the thickness direction, so that the interface barrier and the stability are improved to inhibit electrolyte from migrating and leaking along the interface. The invention discloses an electrolytic cell composite sealing material, which comprises an impermeable layer, a composite matrix layer and an interface transition layer arranged between the impermeable layer and the composite matrix layer; The impermeable layer is a microporous polytetrafluoro