TW201915276A - Light weight & high strength non-asbestos corrugated fiber cement roofing sheets manufactured by autoclave method - Google Patents

Abstract

A light weight and high strength non-asbestos conugated fiber cement roofing sheets comprising, Portland cement, pozzolonic material, fibrous reinforcing material, bentonite clay and additives wherein said fibrous reinforcing material is a combination of plurality of fibers having 8 to 20% of cellulose fiber, 0 to 3% of modified PET fibers and 0 to 6% other fibers optionally containing 0 to 3% rock wool/modified rock wool, organic fiber like jute, bamboo and mineral fibers selected from wollastonite modified or unmodified, sepiolite and mineral fiber.

Description

Lightweight high-strength non-asbestos corrugated fiber cement roofing plate manufactured by high-pressure method

The invention relates to a lightweight high-strength non-asbestos corrugated fiber cement roofing plate manufactured by an autoclave method.

In the past, asbestos-cement compositions have been formed into products such as flat sheets, corrugated sheets, boards, panels, and the like. These boards usually contain 43 to 55% Portland cement, about 30 to 35% siliceous materials and / or fillers, and about 10 to 12% asbestos fibers. The product has many desirable qualities, including high strength, external resistance, and ease of application. Asbestos is a naturally occurring mineral product. But day after day, the availability of high-quality fibers is greatly reduced. Therefore, alternative fibers with similar strength to asbestos and cost-effective corrugated board products must be developed.

Generally, wood pulp and the unique properties of good dispersion in cement / water slurry due to the hydrophilic properties of synthetic fibers such as polyvinyl alcohol and modified polypropylene fibers have been used as a substitute for asbestos. These boards usually contain 70% to 80% Portland cement, about 10 to 20% siliceous materials and / or fillers, and about 4 to 8% such as polyvinyl alcohol and modified polypropylene Fiber synthetic fiber and wood pulp.

The combination of the above fibers and fillers can not subject the final product to hydrothermal curing (autoclave), and only the air curing / water curing method can be used.

Indian Patent Application 6305 / CHE / 2015 describes the manufacture of non-asbestos corrugated sheets by high-pressure methods. In this invention, asbestos fibers are replaced with cotton pulp, modified or unmodified wollastonite, and modified PET fibers. Replace the part of cement with GGBS slag and fly ash. In addition, use silica fume and additives.

US 4,377,415 relates to a cement-wollastonite product, which basically consists of a Portland cement binder with a weight content between about 40% and 90%, and a silica fume with a weight content between about 10% and 60% Composed of stone. The product may contain between about 1% and 15% fiber by weight. If the product contains fibers other than asbestos and will be molded on a Hatschek or other type of wet forming machine, it may contain clay with a weight content of between 2% and 15%, and a weight content of about 0.03 Poly (ethylene oxide) homopolymer between% and 0.5%. The product may also contain silica and / or fillers to replace a portion of wollastonite with a weight content of between about 10% and 40%. The filler can be a waste fiber-cement product or an inert filler material.

US 8,293,003 B1 teaches a cement product incorporating nanocrystalline cellulose and cellulose fibers throughout the product and a method of manufacturing the product.

US 5,122,550 relates to a non-asbestos friction material composition suitable for use as a friction element, which includes: a binder, a reinforcing material, and a structural integrity imparting amount of cellulose ester fibrils.

US 6,284,815 B1 teaches that a non-asbestos friction material has been disclosed, which contains non-asbestos fiber reinforcement materials, thermosetting resin binders and fillers as main components, wherein the fiber reinforcement material is a combination of various non-asbestos fibers and contains sepiolite fibers , Cellulose fiber and acrylic pulp as fiber reinforcement materials. The friction material of the present invention has excellent fading characteristics, effective stability, and the like, and has a low cost.

US Patent No. 8,182,606 B2 describes the manufacture of low-density fiber cement building materials by using low-density additives such as hollow ceramic microspheres, pozzolan (density: 2-25 lbs / cu.ft), and other low-density additives alone or in combination.

Australian Patent 2008348271A1 describes the manufacture of structural fiber cement building materials by using microspheres, calcium silicate, polymer beads, expanded vermiculite / beads / shale and combinations thereof, the structural fiber cement building materials having less than 1.25g / cc density and thickness less than 19 mm.

Indian Patent 279236 describes the manufacture of lightweight cement cellulose fiber reinforced building materials without using any low density additives. In this invention, the flat fiber cement board is manufactured using bauxite and wood pulp by a high-pressure method.

In the present invention, in order to obtain a lightweight and high-strength non-asbestos corrugated board, attempts have been made to increase the amount of pulp and use modified wollastonite with a high aspect ratio.

Attempts have been made to replace some or all amounts of PET fibers with alternative fibers such as mineral fibers, sepiolite, jute fibers, bamboo fibers, and the like.

Part of the cellulose fiber (cotton pulp) has been replaced by modified rock wool fiber.

GGBS slag has been replaced by fly ash to reduce density and make the board lighter.

Similarly, microsilica has been replaced with high surface area fly ash to reduce costs and solve processing problems by maintaining cone and screen filtrate solids.

We have used bentonite to improve interlayer adhesion and used finely ground silica and rice husk ash to replace some of the fly ash.

We have used anionic polyacrylamide flocculants by effectively using fine particles in the form of flocs.

Products that replace asbestos fibers and PVA fibers, silica, and partially replace cement with suitable materials make them unique green products in many ways. The present invention provides a method of manufacturing a lightweight and high-strength non-asbestos fiber cement corrugated board that includes reinforcing fibers as described herein.

The object of the present invention is to provide a lightweight and high-strength non-asbestos corrugated fiber cement roofing plate manufactured by a high-pressure method.

Another object of the present invention is to replace asbestos fiber, wood pulp, PVA, modified polypropylene fiber, micro silica and partially substituted cement to make it a lightweight and high-strength non-asbestos fiber cement corrugated roof board.

Yet another object of the present invention is to use a larger amount of cellulose fibers and high aspect ratio wollastonite / modified wollastonite to replace asbestos fibers, modified polypropylene and PVA fibers.

A further object of the present invention is to use sepiolite, mineral fiber, jute fiber and bamboo fiber to replace part or all of the modified PET fiber.

A further object of the invention is to use modified rock wool fibers to partially replace cotton rag pulp.

Yet another object of the present invention is to manufacture lightweight non-asbestos corrugated board by replacing GGBS with fly ash.

Yet another object of the invention is to improve the adhesion between layers in the green stage by incorporating bentonite in the formulation.

Another object of the present invention is to maintain the cone and screen filtrate solids by replacing micro silica with high surface area fly ash, rice hull ash, and finely ground silica to solve the processing problem.

Another object of the present invention is to effectively use fine particles in the form of flocs by adding an anionic polyacrylamide flocculant.

Still another object of the present invention is to reduce the drying shrinkage of corrugated plates manufactured by hydrothermal (autoclave) curing.

Another object of the present invention is to propose a method for manufacturing building products with improved strength and other characteristics to the product, and to manufacture non-asbestos fiber cement roofing panels by a high-pressure method.

According to the present invention, a lightweight and high-strength non-asbestos fiber cement corrugated roof board is provided, including: Portland cement, pozzolonic material, fiber reinforced material, bentonite and additives, wherein the fiber reinforced material is 8 to 20% cellulose fiber, 0 to 3% modified PET fiber, and 0 to 6% other fiber combinations of multiple fibers, the other fiber optionally contains modified or unmodified wollastonite, Fibrous minerals of sepiolite and mineral fibers.

According to the present invention, there is also provided a method for manufacturing a lightweight and high-strength non-asbestos corrugated fiber cement roofing board, which comprises preparing a slurry; passing the slurry through the steps of forming a film; applying the film to an accumulator roll ) On; and pre-curing and curing in an autoclave to produce the product.

The invention relates to a non-asbestos cement roof fiber product using a high-pressure method, which does not contain asbestos, PVA and original wood pulp, GGBS, and micro silica powder, but contains alone or with cellulose, modified PET fiber, wollastonite / Modified wollastonite, sepiolite, mineral fiber, jute fiber, bamboo fiber, and other fibers used in combination with cement and silicon-containing materials such as fly ash, finely ground silica and rice hull ash, in order to The slurry is formed on the screen and the product is then satisfactorily produced on the machine by screen and / or felt vacuum filtration.

In the following paragraphs, the term cellulose pulp preferably refers to cellulose pulp obtained by mechanically pulping waste jeans cotton or other natural cotton in loose or clothing form. The modified PET fiber has a high molecular weight, has good water dispersibility and is compatible with cement. Wollastonite is a naturally-occurring mineral fiber with a very good aspect ratio. It achieves strength and durability by reducing water movement. Wollastonite can optionally be modified with additives such as vinyl silane, amino silane, glycidyl silane, and vinyl acetoxy silane alone or in combination. Thanks to the present invention, we have achieved strengths similar to lightweight asbestos-based fiber cement boards. Sepiolite is a naturally occurring soft white clay mineral. The fibrous texture of sepiolite makes it suitable for enhancing action. Jute and bamboo fibers are derived from natural plants that have been processed to suit fiber cement applications. Mineral fiber is a naturally occurring mineral product.

Similarly, the fly ash refers to the fly ash produced during the combustion of pulverized coal in thermal power plants. Rice husk ash is ash produced by controlled burning of ground rice husks containing amorphous silica silica.

Bentonite is also a naturally occurring clay mineral, which has very good swelling properties and is used to achieve adhesion between layers.

In the following paragraphs, when the inventor refers to non-asbestos fiber cement sheets, it is the new and inventive non-asbestos fiber cement sheets described in the present invention and environmentally friendly products.

For clarity and a better understanding of the present invention, the method of the present invention and its advantages will now be explained in more detail with reference to known methods of manufacturing such panels.

Step 1-Preparation of slurry According to the present invention, there is provided an improved method for manufacturing a non-asbestos cement roof fiber cement board containing treated reinforcing fibers.

The reinforcing fiber basically includes cellulose pulp with an amount of 8-20% and having fiber openings Deg.SR 12-50, modified PET fiber of 0-3%, and an amount of 0.25 to 10% and having a length of 5 to 40 Wollastonite / modified wollastonite, 0-5% sepiolite, 0-5% mineral fiber, 0-5% jute fiber, 0-5% bamboo fiber, 0-5 % Modified rock wool fiber, 20 to 55% of Portland cement, the silicon-containing material in the adhesive is basically crushed fly ash with a surface area of 2000-4000 cm ² / gm, and the amount is 15-55% , The amount of fine fly ash with a surface area greater than 4000 cm ² / gm is 20-60%, the amount of rice hull ash with a surface area greater than 5000 cm ² / gm is 0-20%, and the amount of finely ground silica is 0 to 25%. And an amount of 1-5% of bentonite and an amount of 0.01 to 2% by weight of fillers, flocs and additives in the total mixture including reinforcing fibers, cement, fillers and additives.

When making the slurry, take care to ensure that the silicon-containing materials, additives and cement are homogeneously mixed with the reinforcing fibers.

The mixing / holding system ensures that the solids are not separated from the aqueous solution, that is, the solids do not settle, thereby obtaining a laminate with uniformly distributed binder and reinforcing fibers in the process.

Step 2: Application of the slurry The formulation thus obtained with respect to the above-mentioned formulation independently operates on a pilot plant and a factory sheet forming machine such as a Hasek machine, in which the film is picked up and superimposed on the stock roll. After reaching the desired thickness, the composite material is cut and flattened, and transported for corrugation and stacking before pre-curing. After a period of time and at a predetermined temperature, the initial curing in the composite makes it strong and obtains sufficient release strength.

Step 3: Curing the aligned product The demolded corrugated board was then placed on a trolley and cured under an autoclave, maintaining a steam pressure of 90 to 130 psi for a duration of 5 to 15 hours. After curing, the cured material in the tram is pulled out and stacked under ambient conditions for further inspection and distribution.

The example uses the above slurry and the method of manufacturing the lightweight and high-strength non-asbestos fiber cement corrugated roof panel requested, in order to replace asbestos fiber, PVA fiber, GGBS, micro silica and use fly ash to partially replace cement . Some typical examples and test results are as follows: Table 1 The present invention - factory test

By using fine fly ash and high aspect ratio modified / unmodified wollastonite in Example 4, superior characteristics are achieved compared to traditional asbestos and non-asbestos fiber cement corrugated roof panels. The product of the invention meets all the requirements of 1S 14871: 2000 Indian standard and ISO 9933: 1995 international standard.

Type test efficacy: 1) Water impermeability: No water droplets were observed under the corrugated board after 24 hours. 2) Frost resistance: freeze-thaw cycle the corrugated board, cool to -20 ° C within 1 to 2 hours and maintain for 1 hour. Thaw in water to ambient temperature within 1 to 2 hours and maintain for 1 hour. After 50 cycles, no cracks, delamination and color changes were observed. 3) Heat and rain: humidify the corrugated board at 2.5l / min / m2 for 2 hours and 50 minutes and heat to 70 ° C for 2 hours and 50 minutes, with an interval of 10 minutes each time. Repeat the cycle 25 times to check for longitudinal and transverse cracks, visual defects, color changes and delamination. The exposed plate passed the test. 4) Warm water: The sample is exposed to warm water at a temperature of 60 ° C for 56 days, and the exposed board meets the standard requirements. 5) Immersion and drying: Test according to EN 494: 2004 (each cycle is immersed in water for 18 hours at ambient temperature and dried for 6 hours in an oven at 60 ° C and a relative humidity of <20%). After 50 cycles, the board was stored at ambient temperature for 7 days and tested, which met the standard requirements. 6) Carbonization test: Carbonization for each cycle is 24 hours, including the following: immersion in water at ambient temperature for 9 hours, drying in a ventilated oven at 60 ° C for 1 hour, purification with carbon dioxide at ambient temperature for 5 hours, at 60 Dry in a ventilated oven at ℃ for 8 hours and cool to ambient temperature within 1 hour. The sample was exposed for 50 cycles. No visual defect cracks were observed. Table 2 The present invention - pilot factory test

In Example 5, rock wool fibers were used to partially replace jeans cotton pulp. In Examples 6 and 7, rice husk ash and ground silica were used as partial replacements for crushed fly ash. In Examples 8, 9 and 10, sepiolite, mineral fiber and jute / bamboo fiber were used as partial or complete replacements of modified PET fiber, respectively.

Through the compression method, it was determined that the lightweight and high-strength non-asbestos fiber cement corrugated roof sheet manufactured by the high-pressure method of the present invention has better bearing capacity than the traditional asbestos and non-asbestos fiber cement corrugated roof sheet.

Claims (14)

A lightweight and high-strength non-asbestos corrugated fiber cement roofing board, including: i) 20 to 60% by weight of general Portland cement; ii) 20 to 60% by weight of pozzolanic materials; iii) 8- 20% by weight of cellulose fiber; iv) 1-5% by weight of bentonite clay; v) 0.1-3% by weight of modified PET fiber; vi) 0.2-6% by weight of modified / unmodified wollastonite Vii) 0.01-2% by weight of additives; and viii) optional 0.1 to 6% by weight of another fiber selected from rock wool, jute fiber, bamboo fiber, sepiolite, ceramic fiber, glass Fiber, mineral fiber, mineral wool and ceramic wool, the other fiber is used alone or in combination with cellulose fiber to (partially or completely) replace modified wollastonite and modified PET fiber, where the density of the product is less than 1200 Kg / M3. The product as described in item 1 of the patent application scope, where general Portland cement is preferably present in the range of 35-50% by weight, pozzolanic material is present in the range of 35-50% by weight, and cellulose fibers are present In the range of 10-16% by weight, bentonite clay exists in the range of 1.5-3% by weight, modified PET fiber exists in the range of 0.2-1% by weight, modified / unmodified wollastonite exists in 2-6% by weight. The product as described in item 1 of the patent application scope, where wollastonite is vinyl silane, amino silane, glycidyl silane and vinyl acetoxy silane used alone or in combination, with silicon content of 0.1 to 3% The weight of limestone is modified, and these silanes help bridge between organic and inorganic materials. The product according to item 1 of the patent application scope, wherein the pozzolanic material is selected from crushed fly ash, fine fly ash, rice husk ash, fumed silica, pozzolan, and optionally ground blast furnace slag. The product as described in item 1 of the patent application range, where optionally 5 to 25% by weight of silicon-containing material such as ground silica is used to partially replace fly ash. The product as described in item 1 of the patent application scope, wherein the cellulose fiber is selected from denim cotton rags, waste cotton cloth and natural cotton. The product as described in item 1 of the patent application scope, wherein the cellulose fiber selected from jeans cotton rags, waste cotton cloths and natural cotton used alone or in combination can optionally be used together with wood pulp. The product as described in item 1 of the patent application scope, in which wollastonite / modified wollastonite has an aspect ratio of 5 to 50. The product as described in item 1 of the patent application, wherein the additive used is a pan-gel, plasticizer, strong plasticizer, flocculant, defoamer, polysiloxane or acrylic based water-reducing admixture. The products mentioned in items 1 to 9 of the patent application range can also be used to manufacture non-asbestos flat sheets / plates. A method for manufacturing a lightweight and high-strength non-asbestos corrugated fiber cement roofing board includes: a) preparing a slurry; b) making the slurry undergo a step of forming a thin film by the Hasek method; c) The film is applied to the stock roll; d) the flat plate is cut from the stock roll after reaching the desired thickness; f) the flat plate is formed into the desired waveform; g) pre-cured and de-stacked; and h) at high pressure Cured in the kettle. The method as described in item 11 of the patent application scope, wherein the slurry is a homogeneous mixture containing silicon material, Portland cement, reinforcing fibers, bentonite and additives. The method as described in item 11 of the patent application range, wherein the curing step is performed in an autoclave maintained at a vapor pressure of 90 to 130 psi for 5 to 15 hours. The method as described in items 11 to 13 of the patent application range, wherein the reinforcing fibers are preferably processed to cellulose pulp having an opening Deg. SR 12-50 and having a length-weight average fiber length lot 0.7 to 2.9 mm.