Mineral fibre[1]It is the fiber obtained from the mineral rock with fibrous structure, and the main components are various oxides, such assilicon dioxide、alumina, magnesium oxide, etc. Its main source is all kinds of asbestos, such as chrysotile, crocidolite, etc.OnMineral fibreOn the basis of a brief overview, several common mineral fibers are introduced, such asAluminium silicate fibre, glass fiber, gypsum fiber, carbon fiber, etc.Mineral fiber is more and more widely used in paper industry.Some of its excellent properties can make paper havePlant fibreNo function of.
Mineral fibers are fibers obtained from mineral rocks with fibrous structure, and the main components are various oxides, such assilicon dioxide, alumina, magnesium oxide, etc., mainly from various asbestos, such as chrysotile, crocidolite, etc[2]。
Good dispersibility, suitable for variousMixing machineMix.Made from artificial rock wool fiber of our factoryBrake liningThe grinding surface of the product is free of cotton ball particles, and the appearance of the product is even and consistent, with good texture.The production process is equipped with special equipment to separate slag balls, and the content of slag balls is low<3%. After the brake lining is made, the manufacturing noise is low[1]。
Recommended dosage
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Drum brake lining for passenger and freight cars: 15% - 35%,
Disc brake lining: 8-25%
Recommended mixing tools
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Pear rake mixer: 6-10 minutes
Vertical shaft high-speed mixer (equipped with high-speed reamer): 4-6 minutes
Fiber technical indicators
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Technical indicators
1. Average fiber length 1.0~3.5mm
2. Average fiber diameter 3.0~8.0 μ m
3 Fiber distribution 40 # 30~40% 60 # 40~60%
4 Fiber burning vector (adjusted according to customer needs)<1% (800 ℃/h)
5 Slag ball content<3%
6 Fiber moisture content<1.5%
7 Fiber capacity 0.10~0.25g/cm3
8 Asbestos composition 0
Spraying construction process
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Preparation before construction
1. Base course
The base course shall be firm, free from cracking, powder dropping, sand raising, hollowing, peeling, lime cracking points, old coatings with poor adhesion, and rust and peeling on the surface of metal materials;The base course shall be clean, and the surface shall be free of dust, laitance, oil stains, rust spots, mildew spots, salt products, moss and other sundries;Before spraying, the base course shall be inspected, and spraying construction can be carried out only after it is qualified.The position and size of hangers for installing various pipelines have been accepted to meet the design and quality requirements, and the reserved pipeline openings shall be marked[3]。
2. Climatic conditions
The temperature of construction environment and spraying base course shall not be lower than 4 ℃, and the normal construction can be carried out only when the wind force in the construction environment is not greater than level 3.On the premise of not affecting the minimum requirements of ambient temperature for spraying construction, the construction site shall be kept ventilated to speed upSpraying materialsDry curing.
3. Spraying equipment and materials
Fiber sprayingCount the bales of cotton, spray several barrels of adhesive, clear the special cotton sprayer, high-pressure glue pump, special spray gun and electric mixer, thickness gauge, thickness measuring needle, setting out tools, mold platen, bucket and liquid measuring cylinder, power equipment and spraying construction scaffolding.
Spraying construction
1. Base treatment
Clean the dust and dirt on the spraying base surface with compressed air or clean water;Check whether the hanging parts and embedded parts are secure, and fasten the loose parts. If the original base surface has been damaged or has serious cracks, repair it first.The doors and windows as well as various equipment, pipelines and non spraying parts shall be protected with plastic film, and the non spraying parts and ventilation pipeline through-hole shall be blocked.Clear the obstacles on the working surface, ensure the smooth movement space and safety of the spraying hand, and maintain the best spraying distance and spraying angle.
2. Spray primer
Before using the adhesive, the adhesive must be mixed with clean water in strict accordance with the mass ratio of glue: water=10:1. It is not allowed to add water at will. It is mixed in a 160 liter plastic bucket. The mixer is used to fully mix to ensure that the adhesive and water are completely and evenly mixed. If the amount is less than the whole bucket, it must be mixed evenly and then taken according to the amount.
debuggingFiber sprayingThe air pressure, glue pump pressure and feeding device of the spraying host shall be adjusted and tested in strict accordance with the equipment operation instructions, and the air pressure range and feeding mixing speed shall be gradually adjusted through sample test spraying, glue flow and cotton output measurement until the fiber spraying state is stable and meets the requirements of the spraying process.Ensure that the adhesive remains atomized and the spray gun nozzle is sprayed continuously and stably.The spraying angle shall ensure that the adhesive and fiber cotton meet 20-30cm in front of the spray gun.The air pressure of the spraying host shall be controlled at 20-30KPa, and it shall be stable. The pressure of the spraying adhesive pump shall be controlled at 1-2KPa, and the cotton spraying amount shall be 0.8kg/min~1.25kg/min. The glue mixture shall be consistent with the cotton spraying amount to achieve good bonding effect.
The thickness scale shall be placed according to the measured area, one for every 5 ㎡ area as the reference of the spraying thickness. The height of the scale shall be 20% higher than the design spraying thickness to ensure that the design requirements are met after shaping.
After the base course surface is cleaned, the prepared spraying adhesive aqueous solution can be used to pre spray the base surface with proper and uniform amount of adhesive, without exposing the bottom or flowing.
3. Spraying insulation layer
Spray the thermal insulation layer, adjust the working air pressure and feeding device to ensure uniform fiber feeding, and the mixing speed is 25-30r/min;Adjust the proportion of water consumption and glue consumption, mix evenly, mix as needed, and spray to the base surface together.The distance between the spray gun and the base surface should be 400 ㎜ - 600 ㎜ to ensure continuous and uniform spraying on the base layer. The spraying angle should be 60-75 °, and the bottom should not be exposed. Direct spraying is not allowed. When spraying to the thickness of the scale, move the spray gun at a uniform speed to ensure the minimum spraying rebound.
4. Surface shaping
After the surface of the sprayed insulation layer is dried for about half an hour, according to the different requirements of the insulation or sound absorption engineering, use a special platen shaping tool for surface processing. When the platen is leveled, it should be pressed down to the design thickness. The internal and external corners should be tidied up and kept in a right angle state.
5. Spraying surface coating
Spray the adhesive surface coating evenly on the reshaped product surface again to enhance the surface strength.If the design requires surface coloring, color paste can be sprayed for coloring after finishing the surface coating.The construction site after spraying shall be cleaned in time, the rebound material shall be removed from the site, and the protective fence and scaffold for spraying shall be removed.
Aluminium silicate fibreThere are two production methods for the products: one is the wet production process of electric arc furnace melting and blowing, and the other is the dry production process of resistance furnace melting and blowing.The main method of producing aluminum silicate fiber and its products in China is the electric arc furnace melt blown wet production process, which mainly produces felt and board products.
Aluminum silicate fiber can be used withPlant fibreCopy, Li Cuizhen, etc[4]Use plant fiber to improveCeramic fiber paperThe strength test can improve the strength of refractory paper by adding different wood pulp content.In addition, aluminum silicate fiber can also replace some paper fillers.Pang Jinjiang et al. used aluminum silicate fiber as filler in paper and mixed it with light calcium carbonate (PCC) filler to explore the optimal addition amount of aluminum silicate fiber as filler and the effect on paper performance after mixing it with PCC.The test results show that the ash content and filler retention of the paper are improved in varying degrees after the addition of aluminum silicate fiber, the tensile strength and folding resistance of the paper are reduced, and the tear index basically remains unchanged;The filler content shall be controlled within 10%, which can basically meet the strength requirements;And the tearing index basically remains unchanged;The whiteness, opacity and other optical properties of the paper have been improved to varying degrees.
glass fibre
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Glass fiber and naturally generatedCellulosic fibreThe difference is that its cross section is round, straight and the diameter is unchanged, and it can be made very fine. Its density is higher than that of cellulose fiber and mostman-made fiberIt is much higher and the available temperature range is much wider.No glass fiberNatural fiberSuch swelling or brooming phenomenon, and less excellentChemical resistanceAnd non hygroscopic, so glass fiber is a good filter material.However, due to the poor strength of glass fiber paper, it can be blended with other plant fibers with good strength to obtain filter materials with good performance.Luoguo et al[5]Through the research on the blending performance of glass fiber and plant fiber, it is found that the beating degree of 25% glass fiber and 75% sisal fiber is 36○The strength and loose thickness can meet the requirements of filter material.
Gypsum fibre
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Gypsum microfiber is also called fiber calcium sulfate, also known asGypsum whisker。Its chemical properties are stable and water solubility is low.It has orthorhombic crystal system and white luster. Fibrous crystals formed under specific conditions have high strength and large length diameter ratio (about 100 ∶ 1), with length of 10 to 100 μ m, and the longest of 250 μ m. The fiber diameter is basically the same.It is a kind of mineral fiber with good performance and low price.Gypsum microfiber is mainly used for resin, rubber, coating, reinforcing agent or functional filler in paper making, and can also be used forfriction material, building materialssealing material Thermal insulation and flame retardant materials.Gypsum microfiber has excellent properties. As a reinforcing agent, the strength of the product can be increased by about 30%.Gypsum fiber with L/D ratio ≥ 100 applied in papermaking can replace part or most of the pulp (50%~70%) as special gypsum paper, and those with L/D ratio ≤ 50 can be used as advanced filler of paper (15%~20%), which can greatly increase the output of paper, reduce the consumption of wood (wood pulp), protect the environment, reduce the wastewater discharge in paper mills, and reduce pollution.
Gypsum microfiber is rich in resources. If it can be widely used in paper industry, it will bring considerable economic benefits.Li Hongkui et al[6]Add gypsum fiber toPlant fibreThe results showed that the physical strength of the paper was the best when 38% gypsum microfiber was added to the softwood pulp;The breaking length, folding strength, tearing index and bursting index of the blank sample increased by 22.8%, 60.6%, 39.9% and 25.4% respectively.stayHardwood pulpThe physical strength of the paper is the best when 22% gypsum microfiber is added to the paper;The breaking length, folding strength, tearing index and bursting index of the blank sample increased by 19.6%, 46.9%, 19.1% and 44.1% respectively.
carbon fibre
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Carbon fiber paper is made of carbon fiber orActivated carbon fiberAnd carbon fiber or activated carbon fiber mixed with other plant or non plant fibers to produce functional paper with special properties.The carbon fibers themselves do not have the properties of interlacing and hydrogen bonding like plant fibers, so adhesives must be used.For functional paper with a certain carbon fiber content, the carbon fiber content can be adjusted between 5% and 60% at the beginning of wet papermaking.
With the development of modern papermaking technology, especially the application of dry papermaking technology and diagonal screen paper machine in functional paper production, the carbon fiber content of carbon fiber paper can theoretically vary from 0% to 100%.
A certain amount of carbon fiber is matched with a corresponding amount of pulp fiber（Plant fibreThe process of making carbon fiber paper with special properties from mineral fibers and synthetic fibers has attracted more and more attention.As a functional material, carbon fiber also has the properties of carbon fiber paper as its composite material, and carbon fiber in carbon fiber paper exists in the form of irregular short fibers, isotropic.In some fields, the use of long fiber composite molding is incomparable
It is proposed that carbon fiber paper has the following properties.
(1) Excellent electric heating performance, as a heating device.
(2) Conductivity, the self resistance, density, thickness and processing technology of carbon fiber paper will affect the conductivity of carbon fiber paper and change the carbon fiber resistance.Carbon fiber paper with different conductivity can be obtained by controlling the production process, which can be used in different fields.
(3) Porosity. Carbon fiber is a uniform porous material. In addition, carbon fiber has a large specific surface area, so carbon fiber paper is an important filter material.
In addition, carbon fiber paper also has lightweight, high temperature resistance, corrosion resistance and other properties.In general, from the functional characteristics of raw carbon fiber, it has a wide range of uses, including the use of its conductive surface heater, FRP substrate manufactured by drug resistance, civil substrate manufactured by mechanical properties, filter materials manufactured by adsorption, battery electrodes, etc[7]。
Sepiolite fiber
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Sepiolite, also known as palygorskite, is a non-metallic ore with good colloidal rheology, stability and adsorption.The particles are fibrous or hair needle shaped. The Mohs hardness is generally between 2 and 2.5. The body is light and the density is 1 to 2.2 g/mthree。Its chemical composition is relatively simple, mainly silicon and magnesium, including SiOtwoThe content is generally 54%~60%, and the content of MgO is mostly 21%~25%.Sepiolite has extremely high thermal stability and high temperature resistance, which can reach 1500~1700 ℃. Its products can be used as high temperature resistant materials, such as fire extinguisher materials, thermal insulation materials, etc.Gao Yujie[8]The sepiolite mixed with other fibers is used as raw material for papermaking research, and paper sheets for different purposes are made by wet method.The beating characteristics of sepiolite are preliminarily discussed, and different binders are used to improve the paper strength of sepiolite.Adsorption paper and flame retardant paper are prepared by mixing sepiolite with coniferous wood pulp, glass wool pulp and other fibers.Sepiolite fiberIt has good paper-making performance. If the conditions are appropriate, wet papermaking can be used.Yan Quanxiang, etc[9]For sepiolite andPlant fibreWhen used in combination, it was found that after adding sepiolite, the strength of paper such as folding strength, tearing strength, tensile index and bursting strength decreased slightly, but by a small margin, while the whiteness increased, and sepiolite retention rate was high, showing the functional characteristics of special paper and flame retardant paper.
Wollastonite
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Wollastonite is a naturally occurring calcium metasilicate (Ca3 (SiO9)).Wollastonite has three kinds of homomorphic polymorphs, namely, mainly the low temperature triclinic variant, the low temperature monoclinic variant (parawollastonite) and the high temperature triclinic variant (also known as pseudowollastonite and B2 wollastonite).Because of wollastoniteSilica tetrahedronThe calcium oxide octahedron is also distributed in a chain like structure, which is parallel to the b axis, and three groups of dissociations {100}, 001}, and {002} parallel to the [010] crystal belt are developed, which enable it to be processed into mineral fibers with high aspect ratio through appropriate mechanical crushing methods.Sun Chuanmin et al[10]The application of modified wollastonite in newsprint.After chemical modification, it is added to deinked pulp to make newsprint.The results show that modified wollastonite can greatly improve the whiteness, opacity and printability of recycled newsprint.Newsprint with 10%~15% modified wollastonite (quantitative 44~47 g/m2) has high whiteness (58%~60%), high strength (fracture length 3800~4000 m) and high opacity (95%~97%), which belongs to high-quality newsprint.On the other hand, since the modified wollastonite has good adsorbability to ink particles, fine fibers and organics, the wastewater discharged from the papermaking process of newsprint with modified wollastonite is easy to treat, and the BOD, COD andHeavy metal elementsThe content is extremely low, reaching the national first level standard for comprehensive emissions.The modified wollastonite shows the dual environmental effects of protecting forests and water bodies in the paper industry, and is a new functional filler with excellent performance in the paper industry.
Vermiculite
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Vermiculite (also known as hydromica) is a kind of iron magnesiumAluminosilicate mineralThe chemical composition is (Mg, Fe, A1) 3 [(Si · Al) 4O10] (OH) 2 · 4H2O.Vermiculite has some characteristics of mica in its natural state, which is scaly and flaky, easy to split into small pieces, and flexible.When heated to 150~950 ℃, the water loss will expand and the volume will increase by 18~25 times.The expanded vermiculite has the advantages of looseness, low density, stable chemical properties, heat insulation, sound insulation, antibacterial, fire resistance, cold resistance, etc.In the paper industry, people make full use of vermiculite's thermal expansion, heat insulation, fire resistance, ion exchange and adsorption properties to produce special paper and treat paper wastewater.
Vermiculite surface is colorful, with light green, dark green, brass, bronze, silver grey, golden yellow and other different colors, and glittering pearl luster.Due to its beautiful color and special texture, vermiculite can be added to the paper copy to make unique paper pages, such as decorative paper.There are studies at home and abroad on the production of wallpaper with paper or other materials as the base material and vermiculite as the filler. The simple production process is: vermiculite raw ore is mixed with adhesive and coated on the paper base after drying, crushing and screening, and then embossing and rewinding.The wallpapers produced by the above process are gorgeous and dazzling, which not only have a sense of primitive roughness, but also have a sense of modern elegance. At the same time, they also have certain thermal insulation, sound absorption, moisture absorption and fire resistance properties.In addition, because vermiculite itself has antibacterial properties, the wallpaper produced by adding vermiculite also has certain antibacterial properties, that is to say, adding vermiculite into the paper material can produce various special papers that integrate decoration and functionality [13].
