Classification and sealing technology of the hotte

2022-08-02
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Classification and sealing process of rubber seal

the function of sealing material is to fill the gap with complex configuration and unfavorable construction, so as to play a sealing role. There are three types of sealing materials: vulcanized rubber gasket or sealing ring; Non vulcanized sealing tape; When there is no fixed shape, I want to have a paste or putty like liquid sealant whose product exceeds this pull

(1) classification according to sealant base material

① rubber type

this sealant takes rubber as base material. Common rubbers include polysulfide rubber, silicone rubber, polyurethane rubber, neoprene and butyl rubber

② resin type

this kind of sealant is based on resin. Common resins include epoxy resin, unsaturated polyester resin, phenolic resin, polyacrylic acid resin, polyvinyl chloride resin, etc

③ oil based type

this sealant is based on oil. Commonly used oils include various vegetable oils such as flax oil, castor oil and tung oil, as well as animal oil (such as fish oil)

(2) classification according to the vulcanization method of sealant

this sealant series uses moisture in the air for vulcanization. It mainly includes single component polyurethane, silicone rubber and polysulfide rubber. The polymer base material contains active genes, which can react with water in the air to form cross-linking bonds, so that the sealant can be vulcanized into a like structure. The moisture in the atmosphere acts as a catalyst in the vulcanization reaction

① chemical vulcanized sealant

two component polyurethane, silicone rubber, polysulfide rubber, neoprene and epoxy resin sealant belong to this category, and are generally vulcanized at room temperature. Some one component chlorosulfonated polyethylene and neoprene sealants and PVC sol paste sealants (such as spot welding adhesives for automobiles) must be vulcanized through chemical reaction under additive conditions

② heat transfer sealant

PVC resin dispersed with plasticizer and rubber containing asphalt are two different types of heat transfer systems. Vinyl resin plasticizers are liquid suspensions at room temperature and harden by heating them into solids; The rubber asphalt sealant is hot-melt

③ oxidation hardening sealant

sealant for caulking or glass installation with dry surface belongs to this type, mainly based on dry and semi dry vegetable oil. The medium-sized oil can be fine creep polymerized, blown or chemically modified. Cobalt naphthenate is used as a drier to accelerate the surface drying without hardening inside; Lead naphthenate hardens both the surface and the interior; Manganese naphthenate makes internal hardening more effective

④ solvent volatilized solidified sealant

this is a sealant based on cohesionless polymer after solvent volatilization. This kind of sealant mainly includes butyl crosslinking sealant, high molecular weight polyisobutylene sealant, acrylate sealant with a certain degree of polymerization, chlorosulfonated polyethylene sealant and neoprene sealant

⑤ non drying permanent plastic sealant

this kind of sealant usually includes sealant based on polybutylene, medium molecular weight polyisobutylene, high viscosity non oxidative adhesive transmission system, which is an important part of the experimental machine, such as styrene based oil, non drying vegetable oil, blown semi dry oil or butyl rubber

domestic sealant

(1) RTV polysulfide rubber sealant is a multi-component material, which is vulcanized into elastomer at room temperature. It is a dry adhesive sealant. XM series sealant is commonly used

(2) RTV silicone rubber sealant

silicone rubber sealant has a variety of special properties, such as high and low temperature resistance, and good electrical insulation performance

(3) anaerobic adhesive

(4) other vulcanized sealants

(5) non vulcanized sealants

most of the non vulcanized sealants are non drying and semi drying, and the ones in the form of putty are also called non vulcanized putty. This kind of sealant is less sensitive to temperature. Within the service temperature range, the sealant is free from deformation, cracking and scaling, and has good long-term storage performance, but low mechanical properties. It is suitable for sealing removable parts or fastening joint surfaces, sealing grooves and filling large structural gaps. It plays a major role in liquid gaskets and is widely used for sealing removable parts

construction method of liquid sealant

the construction method of liquid sealant can be selected according to the state of the glue. Paste seal can be applied by scraper or injection gun; Liquid sealant shall be applied by brush or spraying; The membrane sealant shall be applied by paving method

selection of liquid sealant and construction process

the selection of sealant shall be comprehensively considered according to the requirements of service conditions, seal materials and sealing surface conditions, types and characteristics of sealing media and coating process. Generally, when the stress is large, and the impact force and alternating force are applied, the sealant with high strength shall be selected; When the temperature difference is large, the sealant with good toughness shall be selected

classification of sealant

there are many varieties and types of sealant. In order to meet the same use requirements, several sealants with different base materials can be used; And the same base material can produce sealant with different properties and different uses. Considering the manufacturer and user of sealant, there are many classification methods for sealant. Generally, it can be classified according to the following four methods

types of commonly used sealants

a variety of methods are listed in the previous classification of sealants, of which the most widely used is to divide sealants into vulcanized and non vulcanized types. Room temperature vulcanization sealant is the most widely used in vulcanization sealant, and heating vulcanization sealant is less used. Non vulcanized sealant includes liquid sealant and putty. In addition, the commonly used anaerobic glue is added

(3) classification according to sealant morphology

① paste sealant

this kind of sealant belongs to low-grade sealant, and three main materials are usually used: oil and resin; Polybutene; Bitumen. For the fixed glass commonly used to seal small windows, the maximum joint movement deformation is + 5% or - 5%, and the service life is generally 2 years

② liquid elastomer sealant

this kind of sealant includes liquid polymer that can form an elastic state after vulcanization. They have the ability to withstand repeated joint deformations. The service life of liquid elastomer sealant is generally 15 ~ 20 years. This kind of sealant has high adhesive force and shear strength, and has good flexibility at room temperature. Its disadvantages are high price, requiring primer under normal circumstances, inconvenient on-site mixing of two-component sealant, and sensitive to temperature and humidity during vulcanization

③ hot melt sealant

hot melt sealant is also called hot construction sealant, which refers to the sealant based on the mixture of elastomer and thermoplastic resin

hot melt sealant can be prepared with properties close to liquid elastic sealant, but its advantage over liquid elastomer sealant is that it does not need to add vulcanizing agent

④ liquid sealant

this kind of sealant is mainly used to seal the mechanical joint surface. At present, the ocean freight from Brazil to China is 25.955 US dollars/ton to replace the solid sealing materials (paper, asbestos, cork and vulcanized rubber) to prevent the internal fluid of the machine from leaking from the joint surface. The liquid sealant is also called liquid gasket

(4) according to the performance classification of sealant after construction

① curing sealant

this kind of sealant can be divided into rigid and flexible. The solid formed after vulcanization or solidification of rigid sealant is rarely elastic; Flexible sealant has elasticity and softness after vulcanization

the characteristic of rigid sealant is that it cannot be bent, and generally the joint cannot be moved

the flexible sealant maintains its softness after vulcanization

② non curable sealant

this kind of sealant is a soft curable sealant, which remains dry after construction (the tackifier continuously migrates to the surface). This kind of glue is usually in paste form, which can be applied to the joint with a scraper or brush, and can be used together with sealants with different viscosities and different properties. (end)

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