Resin heavy anti-corrosion "FRP lining anti-corrosion"
1. Definition, characteristics and expression of heavy anti-corrosion of plexiglass lining
2 FRP lining resin heavy-duty resin
3 FRP lining resin heavy-duty fiber
4 FRP lining resin heavy anti-corrosion construction technology
4.1 FRP laminate forming
4.2 FRP lining construction preparation
4.3 FRP lining construction
4.3.1 Rubber compound preparation
4.3.2 General FRP lining process
4.3.3 FRP lining operation for different substrates
22.214.171.124 Metal substrate FRP lining construction
126.96.36.199 FRP concrete lining construction
188.8.131.52 FRP secondary lining construction (FRP lining FRP)
4.4 FRP lining construction safety protection and precautions
5 FRP lining resin heavy anti-corrosion defects and solutions
6 Resin FRP lining new direction of heavy corrosion protection (composite resin heavy anti-corrosion)
1 Definition, characteristics and expression of heavy anti-corrosion of plexiglass lining
FRP lining anti-corrosion is a heavy-duty anti-corrosion form of concrete or carbon steel FRP lining with a thermosetting resin as the matrix resin and a continuous material (mostly glass fiber) as a reinforcing material. The resin has a high overall strength, good toughness, good anti-seepage and corrosion resistance, and convenient construction. However, in the intermittent construction, some need to do secondary bonding treatment, and the thickness of the one-time laminated layer is limited. Irregularities in the construction of irregularly shaped areas are prone to voids.
FRP lining utilizes the chemical stability of FRP and certain physical and mechanical properties to prevent corrosion of equipment. The principle of construction molding is to use resin as a binder for fiber reinforced materials. After curing, the entire inner lining layer is connected to form a solid whole, covering the surface of the protected equipment, thicker than the coating, and with fiber The reinforcing layer has better impermeability and better physical and mechanical properties. However, there is still the possibility of permeability in the FRP lining. In the interfacial layer of the fiber and the resin, once the corrosion starts, the interfacial layer along the fiber directly penetrates into the substrate. In addition, although the FRP lining has certain toughness and impact resistance, it is still a rigid material. It is subject to thermal stress changes, sudden changes in the ambient temperature, and curing shrinkage stress. It also easily leads to cracking of the lining layer and overall shelling.
The FRP lining resin has simple construction, low cost and convenient repair. The material and thickness of the lining layer can be adjusted reasonably with the medium conditions. The rigidity of the lining equipment is carried by carbon steel or concrete shell and can withstand certain external forces. Impact and vibration, therefore, heavy-duty anti-corrosion of FRP lining resin has a wide range of applications in anti-corrosion engineering, and it is also a lot of downstream areas that the author touches:
(1) Internal protection or external protection of containers, tanks, tanks, reactors, towers, etc. in the fields of petroleum, chemical, environmental protection, sulfuric acid, smelting, etc.;
(2) Large underground storage tank or floor lining protection;
(3) The insulation layer of the brick lining;
(4) Repair of secondary FRP lining after failure of other lining layers;
(5) The integrated anti-corrosion of plastic or other equipment is enhanced;
(6) External protection of civil structures.
Commonly classified by resin type, FRP lining resin heavy anti-corrosion manifestation mainly includes: epoxy resin FRP lining, unsaturated polyester resin FRP lining, vinyl ester resin FRP lining, furan resin FRP lining, phenolic resin FRP lining, ring Oxygen coal tar pitch lining. Among them, epoxy, unsaturated, vinyl ester resin FRP lining is the most used in practice.
Depending on the substrate, it can also be expressed as: concrete (cement substrate) FRP lining, carbon steel FRP lining, plastic FRP lining, etc. There are other substrates, but in practice these three substrates are mostly.
2 FRP lining resin heavy-duty resin
Resin plays a major role in impermeability and corrosion resistance in FRP lining. It also acts as a bonding substrate, bonding reinforcement material, and transfer load. It is the key raw material for the ultimate anti-corrosion of FRP lining. Commonly used resins for FRP lining are: epoxy resin, unsaturated polyester resin, vinyl ester resin, phenolic resin, furan resin. Different resins should be selected according to the medium environment according to the corrosion resistance and temperature resistance of the respective resins.
Unsaturated polyester resins, which are mostly used are m-phenyl UPR, bisphenol A-type UPR, and xylene-type UPR. Now, the chlorobridge acid type UPR and the corrosion-resistant benzene type UPR are also increased. Here is a brief introduction. For more detailed information on these resins, please refer to the book "Unsaturated Polyester Resins and Their Applications" by Mr. Zhou Juxing.
The meta-benzene UPR is a polycondensation of isophthalic acid (/anhydride) and a glycol and an unsaturated dibasic acid. It has good acid resistance, temperature resistance and good mechanical properties. It is a medium corrosion resistant UPR resin. . More on the market is 199#. However, the position of the benzene UPR resin in the field of corrosion-resistant FRP lining is very low, and the cost performance is not high at all times, so there are not many cases where it is actually used as a refractory FRP lining.
Therefore, there is a bisphenol A type UPR, which is a UPR prepared by substituting D33 alcohol for diol. The corrosion resistance is better than that between benzene and o-phenyl UPR, and it has certain toughness and better mechanical properties. . It is more resistant to acid and oxidation resistant media. Alkali resistance, although not vinyl ester resin, is much better than xylene type UPR and m-phenylene UPR. More on the market are the 197#, 3301#, 3201# these brands. The final corrosion resistance of bisphenol A type UPR has a great relationship with the substitution ratio of D33 alcohol. The cost of D33 alcohol is much higher than that of ordinary diol. The substitution ratio is larger and the corrosion resistance is better. Of course, this is the reason why the price of bisphenol A type 197 resin on the market is very different. It sells 15-16 yuan and sells 20 yuan. The high price of 197 does not dare to say that D33 alcohol must be high, but the cheap 197 must be D33 alcohol content is very low (this market is impossible for someone to do a loss of business), its ultimate corrosion resistance is actually and ordinary meta-benzene The resin is almost the same, so in order to get better corrosion resistance, we must carefully select the supplier of 197 resin. The 197 resin with good corrosion resistance has very good corrosion resistance and can be used in many places instead of vinyl ester resin. The cost performance is much higher than that of vinyl ester resin, which is also on the market. One reason for the large amount of such a resin is used.
Bisphenol A fumaric acid polyester resin, the typical grade is DSM's 382. This kind of resin is between vinyl ester resin and bisphenol A type UPR, its corrosion resistance and mechanical heat resistance and the current market. It is usually similar to a fumaric acid or adipic acid modified vinyl ester resin. The price/performance ratio is also very high, so there are many users on the market.
Xylene UPR resin, typically X41, 902-A3 of the author's alma mater enterprise Huachang Polymer Co., Ltd., has certain corrosion resistance, but the toughness and mechanical strength of the resin are more than 197, not to mention Said to be compared with vinyl ester resin. In the production process of this kind of resin, there is a lot of waste water, and the color of the final resin is also very poor. According to the current national environmental protection policy, such a resin cannot be produced, and it is impossible for xylene unsaturated resin to pass the environmental protection acceptance in Shanghai. It must be the OEM of the place where the environmental protection in the field is not strict. Only one or two manufacturers in the whole market are supplying this kind of resin. It is not made by other manufacturers, but the performance and comprehensive cost performance of the resin are not high. It can be used at the same price, with better corrosion resistance and better mechanical properties. Good other resin to replace it.
The chlorobridge acid type UPR is typically HS-297 of XXXX Company. It is a UPR which is obtained by partial replacement of dibasic acid and diol by chlorohydric acid. It is resistant to high temperature and flame retardant. The outstanding corrosion resistance is moisture resistant chlorine gas. And hypochlorous acid medium. This kind of resin has been used before, but with the application of vinyl ester resin in the market, especially the application of phenolic vinyl ester resin, the corrosion resistance of chlorobridge acid type UPR is not obvious, and the mechanical properties of the resin And the toughness is poor, the broad spectrum of corrosion resistance of the dehumidified chlorine gas medium is insufficient compared with the vinyl ester resin, and the cost performance is insufficient. Therefore, the resin is now in the field of heavy-duty anti-corrosion of the FRP lining resin, and has been used less and less. It is.
Vinyl ester resin, divided into fumaric acid adipic acid type, acrylic type, TDI modified first two types, standard bisphenol A epoxy type, phenolic epoxy type, brominated flame retardant type, high crosslinked density type, etc. Compared with the previous UPR resins, the vinyl ester resin has a good resistance to acid, alkali, oxidation and organic solvents. The molecular structure is not the same, and its temperature and corrosion resistance are not good. Again, the specific performance of the specific vinyl ester resin is not described in detail here, and the reader can find more information in the previous sections of this book.
Epoxy resin, the most used on-site FRP lining is bisphenol A liquid epoxy resin, E-44 and E-51 are the most used. The biggest advantage of epoxy resin FRP lining is that it has good bonding property with the substrate, small shrinkage and not easy to shell. The cured epoxy glass reinforced plastic lining is resistant to weak acids, weak bases and some solvents, but is insufficient at room temperature to cure heat, and is inferior to vinyl ester resin and furan resin fiberglass lining.
Epoxy resin-catalyzed curing agents (such as imidazole, tertiary amines, acid anhydrides, etc.) are not convenient for on-site room temperature fiberglass lining construction, and cross-linked ethylenediamine and phenalkamine T31 (lower toxicity) are often used. Aromatic amine 590# curing agent curing speed is too slow, not much, polyamide curing agent is a good choice.
In E-44 and E-51, the excessive content of inorganic chlorine and organic chlorine impurities will affect the electrical properties of the final epoxy resin FRP lining. The thinner added during the construction of epoxy resin FRP lining is limited by the length of this book. Please refer to the detailed chapter of the related chapter of Resin Heavy Anti-corrosion Collection.
The phenolic epoxy resin F-44 and F-51 are rarely used in the actual on-site FRP lining project, mainly because of its poor construction workability. This type of epoxy is used more in coating anti-corrosion than in resin. The length of this book is limited, please do not give a detailed introduction, please refer to the detailed introduction of the relevant chapter of the book "Resin Reinforced Corrosion".
Phenolic resin, thermosetting, curing with acid curing agent, cured glass fiber reinforced plastic, excellent acid resistance (especially glacial acetic acid), alkali resistant, non-oxidizing medium, resistant to ethanol, toluene, chlorobenzene, An organic solvent such as ethyl chloride. When the thermosetting phenolic resin is molded at room temperature glass steel, an acidic curing agent is used, and during the curing process, small molecules escape, resulting in insufficient denseness of the final lining layer and poor impermeability. The length of this book is limited. If you don't introduce more phenolic resins, please refer to the related chapters of the book "Resin Reinforced Corrosion".
Furan resin, after curing, is resistant to low concentrations of acid, alkali, acid and alkali, and some organic solvents, but it is very brittle and has poor adhesion to the substrate. The acid curing agent is basically required during construction. Make a barrier. Due to space limitations, do not introduce more furan resin, please refer to the detailed chapter of the "Resin Heavy Antiseptic" collection book.
3 FRP lining resin heavy-duty fiber
Fibers that can be used in FRP linings include natural fibers such as synthetic organic fibers, glass fibers, carbon fibers, and hemp fibers.
Glass fiber, the most applied. There are no alkali (E type), medium alkali (C type), high alkali (type A), acid resistance, but also can be divided into: surface felt, chopped strand mat, woven fabric, continuous yarn, short Cut raw silk, glass scales, etc. For a detailed introduction, please refer to the introduction of Chapter 10, which is not exhaustive here.
Natural fibers such as cotton fibers are not as strong as glass fibers, but are more flexible.
Organic fiber, commonly used polyester fiber and aramid fiber (Kevlar fiber), alkali and salt-resistant solution performance is better than glass fiber, sulfuric acid, hydrochloric acid performance is worse than glass fiber, no silica component, suitable for Glass city lining of fluorinated media. At present, polyester fiber can be made into surface felt (more used in engineering), chopped strand mat, and the model of Tianluo Textile New Material Co., Ltd. is more complete. Polypropylene fiber can be used, but not much. Aramid is more commonly used in building reinforced FRP linings. At this time, epoxy resin is used as the binder resin (the aramid and other thermosetting resins other than epoxy resin have poor bonding properties).
4 FRP lining resin heavy anti-corrosion construction technology
4.1 FRP laminate forming
Before the FRP lining is made, it is necessary to confirm the strength and impact resistance, and it is necessary to make a test laminate. From the ingredients to the flat film, to the bottom of the brush, to the surface felt, to the resin, to the first layer of chopped strand mat, to the second layer of chopped strand mat of the resin, to the resin to spread the continuous fiber cloth, to Press the air bubble to the last layer of the short-cut felt to press the bubble to the surface of the felt to brush the wax-rich resin layer. The detailed introduction and schematic diagram of the whole process can also be found in the “10.3.7 FRP layer” in Chapter 10 of this book. Related introduction.
Typical FRP laminate forming instructions: A. Safety matters; B. Work plan; C. Ensure construction area safety; D. Substrate treatment or mold surface preparation; E. Cutting glass fiber; F. G. Resin weighing and mixing operation; H. Resin standing defoaming; I. Brushing resin; J. Surface felt layering; K. Other layering, layering of other chopped strand mats, fiber cloth, etc.; L. rich resin layer; M. thorough cleaning; N. FRP laminate plate gel curing and cooling.
4.2 FRP lining construction preparation
(1) It must be ensured that the hand or tool can be operated smoothly during construction, and there should be no extremely narrow or dead corners.
(2) The surface of the lining metal casing must be flat and must not have a bump of more than 3 mm.
(3) The screw hole or the lug hole of the inner and outer linings should be increased in diameter, and the increase amount is twice the total thickness of the lining. It must be ground into a smooth transition.
(4) All parts welded to the casing must be welded before the lining is applied, and welding is strictly prohibited after the lining.
(5) Inside the device
peach gum and turpentine in large quantities. . However, not all of the plant's resins can eventually become amber. The resin components secreted by different trees are different. Only the physical and chemical properties of the trees are stable enough. The resin that can resist environmental erosion is likely to go through tens of millions of years to become amber. . In modern plants, only a few trees secrete resins that have the potential to become amber, the most typical of which is New Zealand's Southern Kauri.
Even the resin secreted by a suitable tree has to undergo a lot of environmental tests to become amber, and only a very small part can be finally made into a positive result. After the resin is secreted, the contact air will gradually harden and fall off to the surface of the soil, and oxidation will occur slowly in an oxygen-containing environment. The oxidation process is very slow if measured by the standards of everyday life.
But compared to the geological era of tens of millions of years, the destruction of amber by oxygen is almost instantaneous. Many resins are destroyed by oxygen and organisms on the surface and are naturally degraded. So an anaerobic environment is critical to the formation of amber. The best anaerobic environment on the surface is deep water, such as the bottom of the lake or the bottom of the sea. At present, several important amber producing areas, such as the Baltic Sea, Dominica, Mexico and Myanmar, have direct evidence that these ambers were buried deep in the sea. Fushun Amber was a little special, when an ancient swamp protected it.
The resin stored in the bottom of the water slowly buried in the ground during the deposition process, taking the first step toward amber. In the tens of millions of years of conversion to amber, a large part of the resin is inevitably degraded during the petrochemical process. Only a sufficient amount of resin can eventually form a certain size of amber ore, and this requires a large ancient forest, which has been secreted for a long period of time to form a resin with the potential to form amber.
The current commercial amber mining areas, such as the Baltic Sea and Dominica, are not the areas where the amber forest was located. After the amber forest secretes the resin, it is buried under the water body through transportation. When these resins become amber, they are once again transferred to the areas that are currently discovered through the transfer of geological tectonic movements. The dating of amber is generally determined by the fossils in the sediment layer in which it is located. But these ambers have undergone secondary handling, and they will form a geological age earlier than fossils that are currently in the same sedimentary layer. Burmese amber was initially underestimated by the geological age of its formation until the scientists re-examined the organisms and determined them with the isotope. The generation was only about 100 million years ago in the middle of the Cretaceous.
Third, the relationship between coba lipid and amber
Coba is also a resin fossil. It is a stage in the conversion of resin to amber. Many properties are similar to amber, and it can also encapsulate insects and other contents like amber, so it is often used to impersonate amber. sell. In fact, as a natural resin fossil, coba lipid has a certain collection value, but because of its relatively short age, the physical and chemical properties are not stable enough, and the stock is very large, the value of coba is far from amber. The common coba lipids currently on the market come mainly from Madagascar, Colombia and Borneo, ranging from 1 million to 15 million years.
In general, the color of coba is lighter than amber, but the formation of color has many factors, such as the effect of tree species and oxidation, so it cannot be used as an indicator to distinguish between coba and amber. The color of Madagascar coba is white, which is more distinct from amber; Colombian coba is mostly light in color, but some copas are golden yellow close to amber; Borneo produces both amber and amber. Coba, the two are very similar in appearance, and they are almost indistinguishable by color alone. Similarly, the famous amber producing area, Dominica, also has some copals produced, which can hardly be distinguished by the naked eye.
Since coba is a "semi-finished product" of resin to amber, there are many significant differences from amber, and we can use these differences to accurately identify coba and amber. The hardness of coba is 1.0~2.0, the hardness of amber is 2.0~3.0, and the hardness of normal human nail is just between coba and amber, so it is a simple and effective way to identify Coba with nails. Fat and amber methods. Under the force of the resin fossil surface, the nail can scratch the surface of the coba, but the amber can not be swiped.
The chemical properties of coba lipid are not as stable as amber, mainly because it is more susceptible to oxidation and dehydration, and is also soluble in organic solvents. If alcohol or an organic solvent-containing substance (such as nail polish) is dropped on the surface of the resin fossil, the contact surface of the coba fat will become sticky and lose its luster, and the amber will not change for a short period of time.
NEWECO is one of the leading unsaturated polyester resin manufacturers and suppliers,widely used in automobiles, ships, rail transit, wind power generation, pipe cans, heat and corrosion protection, building materials, stone repair, sanitary ware, artificial stone and other industries. Suitable for hand lay-up, spray, pultrusion, winding, molding, vacuum introduction / RTM, casting and other molding processes. NEWECO Resin is committed to excellence and focuses on the application of composite materials to provide customers with comprehensive solutions.