Abstract: Synthetic mica tape is a mature technology for the manufacture of Class A fire-resistant cables and has been accepted by the cable industry at home and abroad. Mica for various fire resistant cables currently on the market
Belts, each with its own advantages and disadvantages, a variety of materials coexisting for cable manufacturers to choose, to manufacture cables with different fire ratings. However, for 1mm2 and above Class A fire resistant wire and cable, synthesis
Key words: fire resistant cable; synthetic mica tape; application
The application field of Class A durable fire cable is gradually expanding, from the original offshore oil platform to aviation, aerospace, navigation, subway, tunnel, commercial building, hospital, dance hall,
Metallurgical, chemical, and power plants require high fire resistance. In recent years, with the maturity of the A-grade refractory synthetic mica tape manufacturing technology, the A-grade fire-resistant cable made with it
The amount of use is constantly increasing.
As we all know, the refractory mica tape is divided into two grades: A grade (950-1000 ° C) and grade B (750-800 ° C). There are two kinds of phlogopite and synthetic mica tape, which are widely popular in the market. The former one
It is generally suitable for the manufacture of Class B fire-resistant cables, which are suitable for both Class B fire-resistant cables and Class A fire-resistant cables. Class A belt can replace Class B belt to manufacture Class B fire resistant cable, while Class B belt does not.
It can replace the Class A belt to manufacture Class A durable fire cables. Foreign mica tape manufacturers only produce Class B tapes, and there have been no reports of Class A synthetic tapes. Zui near, foreign countries have a film to strengthen Jinyun
The master tape is trying to break into the Chinese market, trying to compete with the synthetic mica tape invented by the Chinese, but the film-type mica tape is also a B-band, and cannot be compared with the synthetic tape at all.
And the price of performance is very different.
This paper discusses the application of synthetic mica tape in Class A fire-resistant cable to clarify the slang of a foreign-made synthetic mica tape and the fire-resistant wire and cable manufactured by it.
And expand the domestic and foreign markets of domestic grade A synthetic mica tape and fire resistant cable.
2. Production and characteristics of synthetic mica tape
In order to overcome the shortcomings of the high heat resistance of muscovite and phlogopite, Chen Yunsheng of Guangzhou Tianhe Yingke New Material Products Co., Ltd. first invented the A-grade refractory synthetic mica tape and passed
It is the pride of the Chinese people to test the UL in the United States and obtain the International Einstein Invention Gold Award from the United States and the patent granted by the Chinese Intellectual Property Office. In 1994, synthetic mica took the lead
It was first tested successfully in Guangzhou Cable Factory, and then gradually applied to the whole country, and has been exported to Europe, America, South Korea and Southeast Asia.
Synthetic mica is a large-sized, crystal-form artificial mica synthesized by replacing the hydroxyl group with fluorine ions under normal pressure conditions. Synthetic mica tape is a mica paper made from synthetic mica
The main material is made by sticking the glass cloth to one or both sides with an adhesive. Paste the glass cloth on the side of the mica paper called "single-sided tape", and paste it on both sides.
Belt". In the manufacturing process, several structural layers are bonded together, then dried by the furnace, then wound, and then cut into tapes of different specifications. In the manufacture of synthetic mica tape
The quality of glass cloth and adhesives is important. The quality of the glass cloth directly affects the mechanical strength of the product, while the adhesive is a key factor in ensuring that the tape does not delaminate. Domestic adhesive
Compared with the quality of imported adhesives, the cost of mica tapes varies.
In addition to the characteristics of natural mica tape, the synthetic mica tape has a small expansion coefficient, a large dielectric strength, a high electrical resistivity and a uniform dielectric constant, and its main feature is high heat resistance.
A Class A fire resistance level (950-1000 ° C) is achieved, while the natural mica tape can only reach Class B (750-800 ° C), even if it is three layers, it is difficult to reach Class A. This is already well known.
real. At the International Cable Expo held in Atlanta, USA a few years ago, synthetic mica tapes have received much attention from various countries and have fully demonstrated the status of synthetic mica tapes. Some people say that abroad
Several large mica tape manufacturers only produce natural mica tapes. First, European and American environmental regulations are strict (this will be discussed below), and second, natural mica tapes can meet Europe.
Standards for fire-resistant cables in the United States. Looking through the cable products samples from Europe and the United States, there is almost no report on Class A fire-resistant cables. I have talked with a European company, he
They took out samples of fire-resistant cables made of film-reinforced mica tape, with a fire rating of Class B, used in the North Sea oil field. They said: "It is difficult to reach Class A with this mica tape." Foreign city
Since there is no A-class mica tape on the field, of course, we have to use the B-class natural mica tape, which is quite normal. In this case, as one Italian company said, "some profiteers shake their donkeys.
Cheat the user."
In addition, the synthetic mica tape is softer than the natural mica tape, wraps around the bag, and has high tensile strength. It is an ideal refractory tape for fire-resistant wires and cables of 1mm2 and above. For several years, domestic is not
Less key projects have specified that fire-resistant cables must be made from Class A synthetic mica tape. 3. About the toxicity of synthetic mica tape
Synthetic mica tape is made from fluorophlogopite raw materials. The structural formula of phlogopite is: Kmg3(AISi3O10)(OH)2, and the structural formula of fluorophlogopite is Kmg3(AISi3O10)(OH)F2,
From the molecular structure, the difference between the two is that the former contains OH ions, the latter contains F ions, and its fluorine content is 8.89%. It is because of the F ion contained in the synthetic mica that heat resistance is achieved.
The level is greatly improved. The characteristics of synthetic mica fluorine are also an excuse for foreign film-reinforced phlogopite tape manufacturers to make a fuss about the need for competition. In fact, for fire-resistant electricity
In terms of cable, fluorine is not a key factor. The question is how much fluorine is released when the cable is burned, and whether the released fluorine reaches a lethal dose. A foreign businessman only said that it is reinforcing in the film.
In the phlogopite tape, a "polymer film" is used, and it is puzzling that the high-polymer is not contained in the fluorine-containing component, but it is recommended to contact the film in the product specification.
Wear gloves when you need to wash your hands with detergent. This shows that the film-reinforced phlogopite belt is toxic.
In the process of manufacturing synthetic mica tape with fluorophlogopite, after grinding and high temperature baking, the fluoride ion in the finished mica tape has been partially volatilized, otherwise the US UL laboratory will not judge
The toxicity of the synthetic mica tape is neglected, and the synthetic mica tape will not be imported in Europe and America. As a scholar in Northern Europe said; "Absolutely non-toxic is impossible, mostly
When organic combustibles burn, Co will be released. Can we say that it is non-toxic? "
In fact, the US environmental protection regulations are not necessarily strict, far less than European countries. For example, the United States still uses a large amount of fluoroplastics to make wire and cable, while fluoroplastics are burning.
The released fluorine is much more than the synthetic mica tape. The US fluoroplastic wire and cable is widely used in various important fields including navigation, aviation and aerospace, even the country.
Fluoroplastic wire and cable are also used in the building. UL Laboratories has never determined which fluoroplastics are negligible. Now, the domestic industry has also called for vigorous development of fluorine.
Plastic wire and cable. The fluoroplastic insulation has been done, who commented? Therefore, we really do not need to use the synthetic mica tape "fluorine" as a reason, and put gold on the American face to fool
Yourself. Even if the halogen-free polymer is basically composed of C=C bonds, will there be no Co emission when burning? Therefore, the synthetic mica tape is not attacked by it.
The "toxicity" that we attack is untenable. As for whether the synthetic mica tape can be used for halogen-free fire-resistant cables, since the UL laboratory has determined that its toxicity is "ignoring", of course
Can be used.
4. Application notes for synthetic mica tape
Each material has a need to pay attention to its use, and synthetic mica tape is no exception.
In general, synthetic mica tapes should be noted for the following during storage and use:
·The storage environment should be dry and ventilated, and the effective storage period is 6 months;
· Do not expose to rain during handling;
· In the case of wet weather, pay attention to the packaging. After unpacking, wrap the remaining mica tape to prevent dust or moisture;
· Do not drag the mica tape on the ground to prevent contamination or damage;
·The tension control of the wrapping should be even to prevent the wrapping from loosening or over-tightening, so as to be smooth, conformable, non-shedding and continuous.
·When the mica is equipped with a joint, a thin adhesive tape is used to prevent the connection path from being too large, which affects the insulation of the package;
· According to the outer diameter of the conductor and the width of the mica tape, choose the appropriate wrapping angle and splicing rate. The wrapping angle is generally 40-50o, and the tiling rate is generally 30-50%.
·When each coil of conductor is wrapped, before being wrapped and insulated, it should be wrapped with suitable packaging to prevent dust, moisture or damage, and prevent bumps during handling.
Depending on the environment in which you use it, you need to pay attention to other safety issues.
5. Comparison of synthetic mica tape and film-reinforced mica tape
The mica type and the reinforcing material used in the synthetic mica tape and the film-reinforced phlogopite tape are different, and the binder may be the same. According to the use of two kinds of mica tapes at home and abroad,
We can make the following comparisons:
(1) The tensile strength of the synthetic mica tape is larger than that of the film-reinforced phlogopite tape. If the winding tension is controlled properly, it will not break when wrapped.
(2) The softness of the synthetic mica tape is slightly worse than that of the film-reinforced phlogopite tape. The Zui is suitable for the winding of wire and cable conductors with a large area of 1mm2 and above, and the wrapping speed is slow;
The film-reinforced phlogopite tape is suitable for high-speed wrapping of special wire and cable conductors up to 1mm2, but requires a special wrapping machine.
(3) The synthetic mica tape is generally double-sided reinforcing, and the mica layer is not easily scratched during the wrapping process, and the mica layer of the film reinforcing mica tape is easily scratched.
(4) In the process of wrapping the synthetic mica tape, the operator does not need to take special anti-virus measures because it does not contain toxins; when using the film to reinforce the phlogopite tape, labor insurance is required.
(5) The synthetic mica tape will stop melting before the extrusion insulation, and will not melt when the deflection is adjusted; the film-reinforced phlogopite will melt at this time, and it is necessary to leave a few meters of bare conductor for extrusion.
Adjusting the bias and causing waste.
(6) The synthetic mica tape has lower requirements on the surface smoothness of the conductor, while the contrast requirement of the film-reinforced phlogopite tape is higher.
(7) Synthetic mica tapes can be used to manufacture qualified fire-resistant cables with ordinary wrapping equipment. The film-reinforced phlogopite tape is also difficult to manufacture using advanced foreign wrapping equipment.
Class A fire resistant cable.
(8) The price of synthetic mica tape is low, the manufacturing cost of fire-resistant wire and cable is low, and the profit is rich; and the price of film-reinforced phlogopite tape is expensive, which increases the cost of wire and cable products.
Relatively low profits.
According to the above comparison, it is not difficult to see that the film-reinforced mica tape, no matter how to reinforce, is still only a very ordinary class B refractory material. Practice has proved that China’s new invention
Class A refractory synthetic mica tape is more reliable and more affordable in practical applications, and is therefore more popular in the wire and cable manufacturing industry at home and abroad.