Fiber cement board doped with degreased short velveteen fibers and preparation method of fiber cement board

Abstract

The invention belongs to the technical field of fiber cement boards, and particularly relates to a fiber cement board doped with degreased short lint fibers and a preparation method thereof, lint solid waste is used as one of raw materials of the fiber cement board, effective utilization of the lint solid waste is realized, dependence on wood fibers is reduced, and production cost is reduced; meanwhile, in the production process of the fiber cement board, clear water is produced by using the fiber reinforced cement board to realize degreasing treatment on the cotton wool solid waste, so that the use of a large amount of strong alkali chemical agents is avoided, the resource utilization rate is increased, the influence on the environment is reduced, and the obtained fiber cement board has good breaking strength.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber cement boards, and in particular relates to a fiber cement board doped with defatted short cotton linter fibers and a preparation method thereof. Background Art

[0002] The cotton lint solid waste generated in industrial production usually contains more than 40% dust and other impurities. These solid wastes have not been effectively utilized, not only occupying a large amount of space, but also causing secondary pollution to the environment during the treatment process, such as the use of a large amount of strong alkaline chemicals, etc., and also wasting precious resources. In addition, in the production process of fiber cement board, the traditional preparation method relies on a large amount of wood fiber, which not only increases the production cost, but also has a negative impact on the environment. Especially when wood fiber mainly relies on imports, the supply chain security is easily affected by the import and export cycle, which is not conducive to the development of the domestic industry. Summary of the invention

[0003] In order to solve the problems raised by the background technology, the present invention utilizes cotton lint solid waste, reduces dependence on imported wood fiber, and reduces production costs. At the same time, in the production process of fiber cement board, it realizes degreasing treatment of cotton lint solid waste, improves resource utilization, and reduces the impact on the environment. A fiber cement board doped with defatted short cotton lint fiber and a preparation method thereof are provided.

[0004] The technical solution of the present invention is as follows:

[0005] The invention provides a fiber cement board doped with defatted short cotton linter fibers. The fiber raw materials in the fiber cement board include defatted short cotton linter fibers and wood pulp fibers, wherein, based on the total weight of the fiber cement board, the defatted short cotton linter fibers account for 1%-4% and the wood pulp fibers account for 1%-5%. The defatted short cotton linter fibers are prepared by soaking cotton linter solid waste in clean water during the production of fiber reinforced cement boards.

[0006] The degreased short cotton linter fiber is prepared by the following steps:

[0007] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and cutting;

[0008] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers.

[0009] The present invention also provides a method for preparing a fiber cement board doped with defatted short cotton linter fibers, wherein the fiber cement board is prepared by the following steps:

[0010] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and cutting;

[0011] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers;

[0012] (3) Raw material pulping: mixing defatted short cotton linter fibers, wood pulp fibers, siliceous materials, calcareous materials, polyvinyl alcohol fibers, and auxiliary fillers to obtain a slurry;

[0013] (4) Forming: The slurry moves forward through the felt of the slurry flow equipment, is dehydrated by the vacuum system, and is wound on the forming cylinder to form a blank. When the thickness of the blank reaches the preset thickness, it is torn off;

[0014] (5) Stacking and pressing: Stack the torn blanks into slabs and press them for dehydration;

[0015] (6) Demolding and curing: The pressurized slab is subjected to first curing, demolding, second curing, and drying in sequence to obtain a fiber cement board.

[0016] In the step (2), the pH value of the clean water used for soaking the fiber reinforced cement board production is not less than 11.

[0017] In the step (2), the beating degree of the defatted short cotton linter fiber is greater than 13 and the wet weight is not less than 6.

[0018] In the step (4), the solid content of the slurry is 14%-16%.

[0019] In the step (5), the pressure of the pressing dehydration is 15-75 MPa and the time is 3-10 min.

[0020] In the step (6), the first curing is static curing or heating pre-curing, and the second curing is autoclave curing or moisturizing curing.

[0021] The temperature of the heating pre-curing is 41-45°C for 12-14 hours; the temperature of the autoclave curing is 180-185°C for 8-8.5 hours.

[0022] In the step (6), the drying temperature is 90-95° C. and the drying time is 2-3 hours.

[0023] Beneficial Effects

[0024] The present invention uses cotton lint solid waste as one of the raw materials of fiber cement board, thereby realizing effective utilization of cotton lint solid waste, reducing dependence on wood fiber, and reducing production costs. At the same time, in the production process of fiber cement board, the clean water produced by fiber reinforced cement board is used to achieve degreasing treatment of cotton lint solid waste, avoiding the use of a large amount of strong alkaline chemicals, thereby improving resource utilization and reducing the impact on the environment. The obtained fiber cement board has good flexural strength. DETAILED DESCRIPTION

[0025] The following examples are intended to illustrate the present invention rather than to further limit the present invention.

[0026] The present invention provides a fiber cement board doped with defatted short cotton linter fibers, wherein the fiber raw materials in the fiber cement board include defatted short cotton linter fibers and wood pulp fibers, wherein, based on the total weight of the fiber cement board, the defatted short cotton linter fibers account for 1%-4% and the wood pulp fibers account for 1%-5%; the defatted short cotton linter fibers are prepared by soaking cotton linter solid waste in clean water during the production of fiber reinforced cement boards.

[0027] Compared with the prior art, which often uses wood pulp fiber as one of the important raw materials for producing fiber cement boards, the present invention uses cotton linter solid waste as one of the raw materials for fiber cement boards, thereby reducing the dependence on wood fiber.

[0028] In addition, the raw materials of the fiber cement board also include 48%-78% siliceous material, 11%-41% calcareous material, 0-3% polyvinyl alcohol fiber, and 1%-3% auxiliary filler.

[0029] In addition, the defatted short cotton linter fiber is prepared by the following steps:

[0030] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and cutting;

[0031] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers.

[0032] The production water is a solution with calcium hydroxide as the main component and a pH value of usually above 12 used in the production process of fiber cement boards. It is circulating water that can be used for production after being precipitated in a water storage tank to remove large particle impurities.

[0033] The present invention also provides a method for preparing the fiber cement board doped with defatted short cotton linter fibers, wherein the fiber cement board is prepared by the following steps:

[0034] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and cutting. It can be crushed to a specified length according to actual needs.

[0035] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers.

[0036] Preferably, the pH value of the fiber reinforced cement board production water used for soaking is not less than 11. The pH can be maintained by filtering the fiber reinforced cement board production water currently used for soaking and then adding it again, or by automatically replenishing new fiber reinforced cement board production water based on pH monitoring. The total soaking time is determined according to the mass of the crushed cotton lint fibers until the cotton lint fibers no longer float within 40 minutes. During soaking, the crushing progress can be accelerated by regular stirring. The fiber reinforced cement board production water can also be heated to shorten the degreasing time.

[0037] In the process of producing fiber cement board, the present invention utilizes the clear water produced by fiber reinforced cement board to realize the degreasing treatment of cotton wool solid waste, thus avoiding the use of a large amount of strong alkaline chemical agents, thereby improving the resource utilization rate and reducing the impact on the environment.

[0038] Considering that there are still some cotton lint fibers that are not fully degreased after wet crushing-immersion degreasing, it is necessary to carry out wet crushing-immersion degreasing again to speed up the degreasing efficiency for the production of fiber cement boards. Preferably, the beating degree of the defatted short cotton lint fibers is greater than 13 and the wet weight is not less than 6.

[0039] After that, the defatted short cotton lint fibers are beaten into a pulp storage tank for standby use. Here, preferably, since the short cotton lint fibers and the wood pulp fibers to be mixed therewith are both lightweight materials, they can be premixed by certain means before pulping. The premixing can be carried out by combining high-pressure gas delivery with cyclone stirring. The wood pulp fibers are sent into the short cotton lint fiber slurry stirred by cyclone flow under high-pressure gas blowing, stirred, and then sent to the homogenizer together.

[0040] (3) Raw material pulping: defatted short cotton linter fibers, wood pulp fibers, siliceous materials, calcareous materials, polyvinyl alcohol fibers, and auxiliary fillers are homogenized and mixed to obtain a slurry.

[0041] (4) Molding: As the slurry moves forward through the continuously running felt of the slurry flow equipment, it is dehydrated by the vacuum system and wound on the molding cylinder to form a blank. When the thickness of the blank reaches the preset thickness, it is torn off.

[0042] When slurry is discharged, for example, the slurry is placed or pumped into a slurry storage tank, and then placed into a slurry headbox by gravity or pumping for production.

[0043] In addition, if the process requires, vibrating screens and refining equipment can be added to reprocess and select the slurry before use.

[0044] Preferably, the solid content of the slurry is 14%-16%.

[0045] (5) Stacking and pressing: Stack the torn blanks into slabs and press them for dehydration;

[0046] When stacking, the blanks torn off the forming cylinder are trimmed and neatly stacked on a pad or a trolley, one plate and one mold at a time. The edge materials and unqualified scrap blanks are recycled.

[0047] The stacked slabs are sent to a press for pressing and dehydration according to the process requirements to discharge a certain amount of water. Preferably, the pressure of the pressing and dehydration is 15-75 MPa and the time is 3-10 minutes.

[0048] (6) Demolding and curing: The pressurized slab is subjected to first curing, demolding, second curing, and drying in sequence to obtain a fiber cement board.

[0049] Preferably, the first curing is static curing or heating pre-curing.

[0050] The slab is sent to a rest curing area or a pre-curing kiln for rest curing or heating pre-curing, wherein the temperature of the heating pre-curing is 41-45°C and the time is 12-14 hours.

[0051] The slab after static curing or pre-curing is separated from the steel formwork, and the formwork is evenly brushed with an environmentally friendly release agent and then returned to the stacking area for recycling; the slab is stacked on a trolley according to the process requirements for the second curing. Preferably, the second curing is autoclave curing or moisturizing curing, for example, it is sent to an autoclave for autoclave curing or placed in a moisturizing curing area for moisturizing curing according to the product process requirements.

[0052] Preferably, the autoclave curing is performed at 180-185° C. for 8-8.5 h.

[0053] Then, the steamed boards are dried to remove a certain amount of water, and then thickness testing, classification and stacking are performed after drying. Preferably, the drying temperature is 90-95° C. and the drying time is 2-3 hours.

[0054] Finally, according to production requirements, the fiber cement board is cut at the edges and corners, or the surface is polished and sanded.

[0055] The present invention utilizes cotton lint solid waste as one of the raw materials of fiber cement board, thereby reducing the dependence on wood fiber and reducing the production cost. Meanwhile, in the production process of fiber cement board, the clean water produced by fiber reinforced cement board is utilized to realize the degreasing treatment of cotton lint solid waste, thereby avoiding the use of a large amount of strong alkaline chemical agents, thus improving the resource utilization rate and reducing the impact on the environment. The obtained fiber cement board has good flexural strength.

[0056] Example 1

[0057] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crusher for crushing and cutting.

[0058] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water used in the production of fiber reinforced cement boards. Stirring is performed regularly during soaking to maintain the pH value at 12 until the cotton lint fibers no longer float within 40 minutes to obtain defatted short cotton lint fibers, which are then put into a slurry storage tank for standby use.

[0059] (3) Raw material pulping: 3% of defatted short cotton linter fiber, 5% of wood pulp fiber, 48% of quartz sand, 41% of cement and 3% of auxiliary filler are homogenized and mixed in a homogenizer for 15 minutes to obtain a slurry.

[0060] (4) Molding: The slurry is pumped to the slurry storage tank, diluted to a concentration of 16%, and then pumped into the slurry head box for production. During the continuous operation of the slurry head equipment, the felt moves forward (the operating speed is 85m / min), dehydrated by the vacuum system, and wound on the molding cylinder into a blank. When the thickness of the blank reaches 9.5mm, it is torn off.

[0061] (5) Stacking and pressurizing: After the torn blanks are trimmed, they are neatly stacked one plate and one mold on a pad or a trolley. The stacking height does not exceed 1.1m. They are stacked into slabs and pressed for dehydration. The pressure is set to 15MPa and the continuous pressurizing time is 3min.

[0062] (6) Demolding and maintenance:

[0063] (61) The pressed slab is sent to a pre-curing kiln for heating and pre-curing. The temperature is controlled at 41°C and the pre-curing time is 12 h.

[0064] (62) The pre-cured slab is separated from the steel formwork, and the formwork is evenly brushed with an environmentally friendly release agent and then returned to the stacking area for recycling. The slab is stacked on a trolley according to the process requirements and sent to an autoclave for autoclave curing. The temperature is 180°C, the insulation time is 8.5 hours, and the temperature is increased for 2 hours and decreased for 4 hours to complete the steam curing of the slab.

[0065] (63) The steamed boards are dried at 90°C for 2.5 hours to ensure that the moisture content is less than 8.5%. After drying, the thickness is tested and the boards are classified and stacked.

[0066] (64) Cut the edges and corners, sand the thickness to 8 mm, and sand the surface to 120 grit to ensure that the surface is flat and free of defects.

[0067] Example 2

[0068] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crusher for crushing and cutting.

[0069] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water used in the production of fiber reinforced cement boards. Stirring is performed regularly during soaking to maintain the pH value at 12 until the cotton lint fibers no longer float within 40 minutes to obtain defatted short cotton lint fibers, which are then put into a slurry storage tank for standby use.

[0070] (3) Raw material pulping: 4% of defatted short cotton linter fiber, 4% of wood pulp fiber, 48% of quartz sand, 41% of cement, and 3% of auxiliary filler are homogenized and mixed in a homogenizer for 15 minutes to obtain a slurry.

[0071] (4) Molding: The slurry is pumped to the slurry storage tank, diluted to a concentration of 16%, and then pumped into the slurry head box for production. During the continuous operation of the slurry head equipment, the felt moves forward (the operating speed is 85m / min), dehydrated by the vacuum system, and wound on the molding cylinder into a blank. When the thickness of the blank reaches 9.5mm, it is torn off.

[0072] (5) Stacking and pressurizing: After the torn blanks are trimmed, they are neatly stacked one plate and one mold on a pad or a trolley. The stacking height does not exceed 1.1m. They are stacked into slabs and pressed for dehydration. The pressure is set to 15MPa and the continuous pressurizing time is 3min.

[0073] (6) Demolding and maintenance:

[0074] (61) The pressed slab is sent to a pre-curing kiln for heating and pre-curing. The temperature is controlled at 41°C and the pre-curing time is 12 h.

[0075] (62) The pre-cured slab is separated from the steel formwork, and the formwork is evenly brushed with an environmentally friendly release agent and then returned to the stacking area for recycling. The slab is stacked on a trolley according to the process requirements and sent to an autoclave for autoclave curing. The temperature is 180°C, the insulation time is 8.5 hours, and the temperature is increased for 2 hours and decreased for 4 hours to complete the steam curing of the slab.

[0076] (63) The steamed boards are dried at 90°C for 2.5 hours to ensure that the moisture content is less than 8.5%. After drying, the thickness is tested and the boards are classified and stacked.

[0077] (64) Cut the edges and corners, sand the thickness to 8 mm, and sand the surface to 120 grit to ensure that the surface is flat and free of defects.

[0078] Example 3

[0079] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crusher for crushing and cutting.

[0080] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water used in the production of fiber reinforced cement boards. Stirring is performed regularly during soaking to maintain the pH value at 12 until the cotton lint fibers no longer float within 40 minutes to obtain defatted short cotton lint fibers, which are then put into a slurry storage tank for standby use.

[0081] (3) Raw material pulping: 1% of defatted short cotton linter fiber, 2% of wood pulp fiber, 78% of quartz sand, 11% of cement, 3% of polyvinyl alcohol fiber, and 5% of auxiliary filler are homogenized and mixed in a homogenizer for 15 minutes to obtain a slurry.

[0082] (4) Molding: The slurry is pumped to the slurry storage tank, diluted to a concentration of 16%, and then pumped into the slurry head box for production. During the continuous operation of the slurry head equipment, the felt moves forward (the operating speed is 85m / min), dehydrated by the vacuum system, and wound on the molding cylinder into a blank. When the thickness of the blank reaches 9.8mm, it is torn off.

[0083] (5) Stacking and pressurization: After the torn blanks are trimmed, they are neatly stacked one plate and one mold on a pad or a trolley. The stacking height does not exceed 1.1m. They are stacked into slabs and pressed for dehydration. The pressure is set to 75MPa and the pressurization time is 10min.

[0084] (6) Demolding and maintenance:

[0085] (61) The pressed slab is sent to a pre-curing kiln for heating and pre-curing. The temperature is controlled at 41°C and the pre-curing time is 12 h.

[0086] (62) The pre-cured slab is separated from the steel formwork, and the formwork is evenly brushed with an environmentally friendly release agent and then returned to the stacking area for recycling; the slab is stacked on a trolley according to the process requirements and sent to the moisturizing curing area for moisturizing curing for 28 days.

[0087] (63) After curing, the edges and corners of the board are cut, the thickness is sanded to 8mm, and the surface is sanded to 120 mesh to ensure that the surface is flat and flawless.

[0088] Example 4

[0089] (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crusher for crushing and cutting.

[0090] (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water used in the production of fiber reinforced cement boards. Stirring is performed regularly during soaking to maintain the pH value at 12 until the cotton lint fibers no longer float within 40 minutes to obtain defatted short cotton lint fibers, which are then put into a slurry storage tank for standby use.

[0091] (3) Raw material pulping: 2% of defatted short cotton linter fiber, 1% of wood pulp fiber, 78% of quartz sand, 11% of cement, 3% of polyvinyl alcohol fiber, and 5% of auxiliary filler are homogenized and mixed in a homogenizer for 15 minutes to obtain a slurry.

[0092] (4) Molding: The slurry is pumped to the slurry storage tank, diluted to a concentration of 16%, and then pumped into the slurry head box for production. During the continuous operation of the slurry head equipment, the felt moves forward (the operating speed is 85m / min), dehydrated by the vacuum system, and wound on the molding cylinder into a blank. When the thickness of the blank reaches 9.8mm, it is torn off.

[0093] (5) Stacking and pressurization: After the torn blanks are trimmed, they are neatly stacked one plate and one mold on a pad or a trolley. The stacking height does not exceed 1.1m. They are stacked into slabs and pressed for dehydration. The pressure is set to 75MPa and the pressurization time is 10min.

[0094] (6) Demolding and maintenance:

[0095] (61) The pressed slab is sent to a pre-curing kiln for heating and pre-curing. The temperature is controlled at 41°C and the pre-curing time is 12 h.

[0096] (62) The pre-cured slab is separated from the steel formwork, and the formwork is evenly brushed with an environmentally friendly release agent and then returned to the stacking area for recycling; the slab is stacked on a trolley according to the process requirements and sent to the moisturizing curing area for moisturizing curing for 28 days.

[0097] (63) After curing, the edges and corners of the board are cut, the thickness is sanded to 8mm, and the surface is sanded to 120 mesh to ensure that the surface is flat and flawless.

[0098] In the above embodiments, the defatted short cotton linter fibers all reached a beating degree of 15 and a wet weight of 8.

[0099] Experimental Results

[0100] The fiber cement boards prepared in Examples 1-4 were tested for density and flexural strength, specifically according to the testing method in GBT7019-2014. The test results are shown in Table 1.

[0101] Table 1 Test results

[0102]

[0103] As can be seen from Table 1, the fiber cement boards prepared by the present application in Examples 1-4 maintain a flexural strength comparable to that of traditional products and meet the high standards of the construction industry.

Claims

1. A fiber cement board mixed with defatted short cotton linter fibers, characterized in that: The fiber raw materials in the fiber cement board include defatted short cotton linter fibers and wood pulp fibers, wherein, based on the total weight of the fiber cement board, the defatted short cotton linter fibers account for 1%-4% and the wood pulp fibers account for 1%-5%; the defatted short cotton linter fibers are obtained by soaking cotton linter solid waste in clean water during the production of fiber reinforced cement boards.

2. The fiber cement board doped with defatted short cotton linter fibers according to claim 1, characterized in that: The degreased short cotton linter fiber is prepared by the following steps: (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and segmenting; (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers.

3. A method for preparing a fiber cement board doped with defatted short cotton linter fibers as claimed in claim 1, characterized in that: The fiber cement board is prepared by the following steps: (1) Wet crushing: Add clean water from fiber reinforced cement board production and cotton lint fibers after dust removal from cotton lint solid waste screening into the crushing equipment for crushing and segmenting; (2) Soaking and degreasing: The crushed cotton lint fibers are soaked in clean water to obtain defatted short cotton lint fibers; (3) Raw material pulping: mixing defatted short cotton linter fibers, wood pulp fibers, siliceous materials, calcareous materials, polyvinyl alcohol fibers, and auxiliary fillers to obtain a slurry; (4) Forming: The slurry moves forward through the felt of the slurry flow equipment, is dehydrated by the vacuum system, and is wound on the forming cylinder to form a blank. When the thickness of the blank reaches the preset thickness, it is torn off; (5) Stacking and pressing: Stack the torn blanks into slabs and press them for dehydration; (6) Demolding and curing: The pressurized slab is subjected to first curing, demolding, second curing, and drying in sequence to obtain a fiber cement board.

4. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (2), the pH value of the clean water used for soaking the fiber reinforced cement board production is not less than 11.

5. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (2), the beating degree of the defatted short cotton linter fiber is greater than 13 and the wet weight is not less than 6.

6. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (4), the solid content of the slurry is 14%-16%.

7. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (5), the pressure of the pressing dehydration is 15-75 MPa and the time is 3-10 min.

8. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (6), the first curing is static curing or heating pre-curing, and the second curing is autoclave curing or moisturizing curing.

9. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 8, characterized in that: The temperature of the heating pre-curing is 41-45°C for 12-14 hours; the temperature of the autoclave curing is 180-185°C for 8-8.5 hours.

10. The method for preparing the fiber cement board doped with defatted short cotton linter fibers according to claim 3, characterized in that: In the step (6), the drying temperature is 90-95° C. and the drying time is 2-3 hours.

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