The cast iron manhole cover developed earlier, and was cast and molded from pig iron. Its bearing capacity and weather resistance are good; the disadvantage is that the production cost is high and the production process pollutes the environment; once it is broken, it completely collapses and the safety protection function is completely lost; part of the production The company's profit is only for the sake of cutting corners, making the product's load-carrying capacity impossible to guarantee; the lack of machining of the contact surface between the well cover and the well seat results in poor contact and causing a large beating noise; in addition, the cast iron manhole cover has a high recycling value, and illegal elements are profitable. The cast iron manhole cover was stolen and smashed and sold to a waste recycling station. Especially in recent years, as the price of steel has risen, the theft of cast iron manhole covers has been serious.
Resin usually refers to a range of softening or melting after heating. When softened, it has a tendency to flow under the action of external forces. It is a solid, semi-solid, or liquid organic polymer at normal temperature. Broadly speaking, any polymer that can be used as a raw material for processing plastic products is called a resin. Resin is divided into natural resin and synthetic resin. Natural resins refer to amorphous organic substances such as rosin, amber, shellac, etc., obtained from the secretions of plants and animals in nature. Synthetic resin refers to a resin product obtained by chemical synthesis of simple organic matter or chemical reaction of certain natural products. Natural resins can be classified according to the resin composition and the history of resin formation.
According to the basic components of the resin can be divided into three categories:
①Pure resin, which is a resinous substance composed of terpenoids and crude essential oil. Generally insoluble in water, but soluble in organic solvents such as rosin.
②Gum-containing resin or gum resin is composed of polysaccharides. It is soluble in water or swells with water, but insoluble in alcohol and organic solvents such as frankincense.
③Olein resin or fragrant gum refers to resin that contains more essential oils and is soluble in oil. According to the formation history of the resin, it can be divided into fossil resin, semi-fossil resin and fresh resin. The latter is the most important source of natural resins. Some natural resins are named after the names of the earliest ports for container shipments, such as Rima resin and Coba resin.
Synthetic resin is a viscous liquid or a solid that can be softened by heating. When heated, it usually has a melting or softening temperature range. It can show a plastic flow state under external forces. Some properties are similar to natural resins. The most important application of synthetic resins is the manufacture of plastics. In order to facilitate processing and improve performance, additives are often added, and sometimes they are also directly used for processing and forming, so they are often synonymous with plastics.
Synthetic resin is also a basic raw material for manufacturing synthetic fibers, coatings, adhesives, insulating materials and the like. There are many types of synthetic resins. According to the main chain structure, there are carbon chain, hetero chain and non-carbon chain synthetic resins; according to the characteristics of the synthetic reaction, there are addition polymerization type and polycondensation type synthetic resins. In practical applications, they are often divided into thermoplastic resins and thermosetting resins according to their thermal behavior. There are abundant sources of raw materials for the production of synthetic resins. In the early days, coal tar products and calcium carbide acetylene were mainly used, and now most of them are oil and natural gas products, such as ethylene, propylene, benzene, formaldehyde, and urea. The synthetic resin is produced by bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, melt polymerization, and interfacial polycondensation.
Plastics: Materials with plastic behavior. The so-called plasticity refers to the deformation that occurs when an external force is applied. After the external force is canceled, it can still maintain the state when the force is applied. The elastic modulus of plastic is between rubber and fiber, and it can deform to a certain extent when subjected to force. Soft plastic is close to rubber, and hard plastic is close to fiber.
Plastic refers to a material that uses resin (or polymerized directly with monomers during processing) as its main component, and additives such as plasticizers, fillers, lubricants, and colorants as auxiliary components that can be flow-molded during processing. Plastic is a synthetic polymer compound that can be freely changed in shape. Plastic is a material synthesized by polymerization or condensation reaction using monomer raw materials. It is composed of synthetic resin and additives such as fillers, plasticizers, stabilizers, lubricants, and colorants. Its main component is synthetic resin.
The resin manhole cover uses glass fiber and its products (glass cloth, tape, felt, yarn, etc.) as the reinforcing material, and synthetic resin as the matrix material, mainly composed of unsaturated polyester resin, filler, initiator, thickener, It consists of low shrinkage additive, film mold agent, pigment and reinforcing material. The resin composite manhole cover is divided into BMC and SMC, and SMC and BMC materials are all composite materials. BMC (DMC) material is the abbreviation of Bulk (Dough) molding compounds, that is, ball molding compound. It is often referred to as unsaturated polyester pellet molding compound in China. The main raw materials are GF (chopped glass fiber), UP (unsaturated resin), MD (filler), and various additives, which are fully prepregs. DMC materials were first applied in the former West Germany and the United Kingdom in the 1960s, and then developed significantly in the United States and Japan in the 1970s and 1980s, respectively. Because BMC lump molding compound has excellent electrical properties, mechanical properties, heat resistance, chemical resistance, and adapts to various molding processes, it can meet the performance requirements of various products. It is widely used in automobile manufacturing and railway transportation. , Construction accessories, mechanical and electrical products.
SMC composite material is the abbreviation of Sheet molding compound, that is, sheet molding compound. The main raw materials are composed of GF (special yarn), UP (unsaturated resin), low shrinkage additive, MD (filler) and various additives. It first appeared in Europe in the early 1960s, and around 1965, the United States and Japan successively developed this process. At the end of the 1980s, China introduced foreign advanced SMC production lines and production technology. SMC composite materials and SMC molded products have excellent electrical insulation properties, mechanical properties, thermal stability, and chemical corrosion resistance. Therefore, the application range of SMC products is quite common. The current development trend is that SMC composites replace BMC materials.
Resin manhole covers gradually integrate into our city life with its unique advantages. Streets, alleys, urban arterial roads, garden quarters, underground garages, factory workshops, etc. are everywhere. Due to the strong designability of resin composite materials, it is possible to design corresponding specifications and add patterns or colors according to the different intentions and requirements of users. Once the products are in place with the infrastructure, the overall image will be more beautiful. And more coordinated with the surrounding environment. Its non-recyclability and service life reduce the overall cost of maintenance and use of the project to a relatively low level.
The popularity of resin manhole covers is fundamentally that their comprehensive performance and economic indicators have surpassed those of cast iron manhole covers, and it can also solve the problem of theft of cast iron manhole covers. At the same time, it can reduce the consumption of resources and has important economic and social values. The manhole cover has the advantages of light weight and high strength, simple molding, low car milling noise, good chemical resistance, good acid and alkali resistance, and beautiful appearance.It has advantages not found in cast iron manhole covers. The surface pattern of the resin inspection manhole cover is beautifully designed and bright in color. Adjust, beautify the urban environment, easy to use, light weight, resin inspection manhole cover has no recycling value, natural anti-theft, resin inspection manhole cover through scientific formula, advanced technology, perfect technical equipment to make this product at -50 ° C --- Normal use in + 150 ° C environment, acid and alkali resistance, corrosion resistance, abrasion resistance, vehicle rolling resistance, long service life, meet the standard of resin manhole cover.
Resin manhole cover has the advantages of light weight and high strength, excellent fatigue resistance, breakage safety, simple molding, low rolling noise, good chemical resistance, good acid and alkali resistance, and beautiful appearance. Its comprehensive performance and economic indicators have surpassed cast iron manhole covers, and it can also solve the problem of stolen cast iron manhole covers. At the same time, it can reduce the consumption of resources, which has important economic and social values.
1. Strong anti-theft performance: Resin composite material manhole cover is made of unsaturated resin, glass fiber and other materials and reinforced skeleton through special production process. After high temperature grinding and pressing, the material has no recycling value, and it is very difficult to take out the steel bar. The cost exceeds the value of the steel bar) so it has the function of active anti-theft.
2. Large bearing capacity: the bottom adopts a special pan-bottom structure, which increases the load area by dozens or even dozens of times. The continuous reinforcing fiber yarn used guarantees that the fiber yarn and the glass fiber cloth are integrated into one material, so that the product has sufficient bearing capacity. And meet or exceed the standard.
3. Long service life: through the use of high-performance resin, glass fiber and special production process formula, to ensure the penetration of resin in glass fiber, greatly enhance the adhesion between the two, so that the material under the action of cyclic loading, not Internal damage occurs, which guarantees the service life of the product and the same superiority of other resin composite manhole covers. Eliminate the disadvantages of poor adhesion.
4. Beautiful and practical, high-grade: According to the needs of high-end customers, we can make personalized logos with complex logos and multiple colors on the same well cover surface, making the patterns delicate, bright and clear. According to customer requirements, we can make all kinds of imitation stone surfaces and colors the same as various stone pavements.
5. High temperature / low temperature resistance, good insulation performance, strong corrosion resistance: the product is corrosion-resistant, non-toxic and harmless. Without metal additives, it has a real insulation effect. Can be used in complex, changeable, harsh, and demanding places. The product has been tested by relevant authoritative testing agencies, and has obvious acid and alkali resistance, corrosion resistance, anti-aging and other indicators have reached and exceeded standards.
6.Environmental protection, non-slip, low noise: This product does not slip, no harsh noise and anti-interference phenomenon after the car is rolled. At the same time, due to the light weight of the product and the precise closure of the cover and seat, it overcomes other problems such as "jumping, rocking, ringing, and shifting" of other inspection manhole covers.