High-strength dust-free paper and preparation method thereof

Abstract

The invention provides high-strength dust-free paper and a preparation method thereof, and the preparation method comprises the following steps: taking treated hot-melt ultra-short fibers and fluff pulp wood pulp fibers, and adding modified soybean protein and microparticle silica gel into the treated hot-melt ultra-short fibers and fluff pulp wood pulp fibers; under the action of vacuum suction under a forming net, the paper falls down through a forming head and is adsorbed to the forming net, and a dust-free paper fiber net is formed; performing compaction; conveying to a hot melting oven net, heating and solidifying; and carrying out surface treatment and shaping through a cooling system. According to the preparation method, the fiber structure of the dust-free paper is modified by adopting the modified soybean protein and the silica gel particles, the modified soybean protein has three important functional groups, an azetidine structure can react with-COOH on fluff pulp wood pulp fibers, a covalent bond is formed between the azetidine structure and the-COOH, and the strength of the dust-free paper can be obviously improved; epichlorohydrin and epoxy groups can react with primary amine or secondary amine of soybean protein, and are crosslinked on the surface of fluff pulp wood pulp fiber to form a three-dimensional cross-linked network structure, so that the strength of the paper is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of functional paper, and in particular to high-strength dust-free paper and a preparation method thereof. Background Art

[0002] Dust-free paper, also known as dry-laid papermaking nonwoven fabric, also known as dry-laid paper and puffed core material, its key process is the air-laid web process. Air-laid dry-laid papermaking is a technology that uses short fibers to make paper. Because no water resources are used in the production process of the paper web (its key process forming process), it is called dry-laid papermaking technology, and its products are also called "dust-free paper" in my country. The main fiber used to produce dust-free paper is fluff pulp produced from coniferous wood. The fluff pulp is broken into loose single fibers in a pulverizer. Other natural fibers or shorter synthetic fibers can also be used. Air is used instead of water as a carrier for dispersing and transporting fibers. During molding, air is sucked instead of dehydration to make the fibers spread on the molding net to form a paper web. During the molding process, the bonding between the fibers is not based on hydrogen bonds, but on polymer adhesives or hot-melt fibers themselves being heated and melted to strengthen. Dust-free paper is similar to ordinary paper, but it is soft, fluffy, elastic, has good dry and wet strength, thickness and high water absorption. These excellent physical properties make dust-free paper widely used in sanitary care products, industrial wipes, special medical products and other fields. Although dust-free paper has many advantages, it also has many disadvantages: such as high cost, low strength, poor durability, and difficult recycling. Therefore, on the basis of the original dust-free paper, further improving its various performances, such as strength, is a content that needs to be studied and explored at present. Summary of the invention

[0003] Technical problem to be solved: The purpose of the present invention is to provide a high-strength dust-free paper and a preparation method thereof. The fiber structure of the dust-free paper is modified by modified soy protein and micro-silica gel. After carboxymethylation and epichlorohydrin modification, the soy protein can produce three important functional groups, including azetidine structure, epichlorohydrin and epoxy group. Among them, the azetidine structure can react with the -COOH on the fluff pulp fiber to form a covalent bond, which can significantly improve the strength of the dust-free paper; at the same time, epichlorohydrin and epoxy group can react with the primary amine or secondary amine of soy protein, cross-link themselves on the surface of the fluff pulp fiber to form a three-dimensional cross-linked network structure, thereby improving the strength of the paper.

[0004] Technical solution: A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Take 20-30 parts of hot-melt short fibers for opening, and 50-70 parts of fluff pulp fibers for opening after crushing, and then treat with plasma; Step 2: Add 10-15 parts of modified soy protein and 2-5 parts of micro-silica gel and mix; Step 3: Sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net to form a dust-free paper fiber web; Step 4: compacting the dust-free paper fiber web; Step 5: Send it to the hot melt oven net and heat it at a temperature of 125-160°C for consolidation; Step 6: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Furthermore, the plasma treatment conditions are: power of 10-30W, pressure of 30-40Pa, and time of 2-5s. Furthermore, the preparation method of the modified soy protein is: S1: Mix 4-5g soy protein, 5g sodium chloroacetate and 10g water, add 4.5g 45% NaOH solution, heat to 40℃ for 2h, and then quickly heat to 70℃ for 2h; S2: ultrafiltration with an ultrafiltration membrane, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soybean protein solution; S3: Slowly add 7-8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath and react for 2-3 hours to obtain a modified soy protein solution; S4: filtering and drying to obtain modified soy protein. Furthermore, the molecular weight cutoff of the ultrafiltration membrane in S2 is 10 kDa. Furthermore, the micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g. Furthermore, in step 3, the molding humidity is 60-75%. Furthermore, in step 4, the compaction temperature is 80-90° C. and the pressure is 15-20 N / mm. Beneficial effects: 1. The present invention uses modified soy protein and micro-silica gel to modify the fiber structure of dust-free paper. After being carboxymethylated and modified with epichlorohydrin, the soy protein can produce three important functional groups, including azetidine structure, epichlorohydrin and epoxy group. Among them, the azetidine structure can react with the -COOH on the fluff pulp fiber to form a covalent bond, which can significantly improve the strength of the dust-free paper; at the same time, epichlorohydrin and epoxy group can react with the primary amine or secondary amine of soy protein, cross-link themselves on the surface of the fluff pulp fiber to form a three-dimensional cross-linked network structure, thereby improving the strength of the paper. 2. The micro-silica gel added in the present invention is a three-dimensional network structure connected by smaller silicon particles, forming a composite stable structure of large three-dimensional cross-linked network structure and small three-dimensional network structure interwoven inside the dust-free paper, thereby improving the tensile strength of the paper. At the same time, the micro-silica gel itself can also improve the smoothness and wear resistance of the paper. DETAILED DESCRIPTION Example 1 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 4g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 7 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 2 hours, filter, and dry to obtain modified soy protein; Step 4: 20 kg of hot-melt ultra-short fibers are taken for opening, and 50 kg of fluff pulp fibers are opened after being crushed, and then subjected to plasma treatment. The treatment conditions are: power 10 W, pressure 40 Pa, and time 5 s; Step 5: Add 10kg modified soy protein and 2kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 60%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 80°C and a pressure of 15N / mm; Step 8: Send it to the hot melt oven net and heat it at 125°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Example 2 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 2-3 hours, filter, and dry to obtain modified soy protein; Step 4: 25 kg of hot-melt ultra-short fibers are taken for opening, and 55 kg of fluff pulp fibers are opened after being crushed, and then subjected to plasma treatment. The treatment conditions are: power 15 W, pressure 35 Pa, and time 5 s; Step 5: Add 10kg modified soy protein and 3kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 65%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 17N / mm; Step 8: Send it to the hot melt oven net and heat it at 130°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Example 3 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 7-8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 2-3 hours, filter, and dry to obtain modified soy protein; Step 4: 25 kg of hot-melt ultra-short fibers are taken for opening, 60 kg of fluff pulp fibers are crushed and opened, and then subjected to plasma treatment. The treatment conditions are: power 20 W, pressure 35 Pa, time 4 s; Step 5: Add 15kg modified soy protein and 4kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 70%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 18N / mm; Step 8: Send it to the hot melt oven net and heat it at 140°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Example 4 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 3 hours, filter, and dry to obtain modified soy protein; Step 4: 25 kg of hot-melt ultra-short fibers are taken for opening, 65 kg of fluff pulp fibers are crushed and opened, and then subjected to plasma treatment. The treatment conditions are: power 25 W, pressure 35 Pa, time 4 s; Step 5: Add 15kg modified soy protein and 4kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 70%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 19N / mm; Step 8: Send it to the hot melt oven net and heat it at 150°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Example 5 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 3 hours, filter, and dry to obtain modified soy protein; Step 4: 25 kg of hot-melt ultra-short fibers are taken for opening, 65 kg of fluff pulp fibers are crushed and opened, and then subjected to plasma treatment. The treatment conditions are: power 30 W, pressure 40 Pa, and time 5 s; Step 5: Add 13kg modified soy protein and 5kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 75%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 90°C and a pressure of 20N / mm; Step 8: Send it to the hot melt oven net and heat it at 150°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Example 6 A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 3 hours, filter, and dry to obtain modified soy protein; Step 4: 30 kg of hot-melt ultra-short fibers are taken for opening, and 70 kg of fluff pulp fibers are crushed and opened, and then subjected to plasma treatment. The treatment conditions are: power 10 W, pressure 40 Pa, and time 5 s; Step 5: Add 15kg modified soy protein and 5kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 75%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 90°C and a pressure of 20N / mm; Step 8: Send it to the hot melt oven net and heat it at 160°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Comparative Example 1 The difference between this embodiment and embodiment 4 is that modified soy protein is not added. Specifically: A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Take 25kg of hot-melt ultra-short fibers for opening, and 65kg of fluff pulp fibers for opening after crushing, and then treat with plasma. The treatment conditions are: power 25W, pressure 35Pa, time 4s; Step 2: Add 4kg of micro-silica gel and mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 3: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 70%, forming a dust-free paper fiber web; Step 4: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 19N / mm; Step 5: Send it to the hot melt oven net and heat it at 150°C to solidify it; Step 6: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Comparative Example 2 The difference between this embodiment and embodiment 4 is that no micro-silica gel is added, as follows: A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Mix 5g of soy protein, 5g of sodium chloroacetate and 10g of water, add 4.5g of 45% NaOH solution, heat to 40°C for 2h, and then quickly heat to 70°C for 2h; Step 2: ultrafiltration with an ultrafiltration membrane with a molecular weight cutoff of 10 kDa, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soy protein solution; Step 3: Slowly add 8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath, react for 3 hours, filter, and dry to obtain modified soy protein; Step 4: 25 kg of hot-melt ultra-short fibers are taken for opening, 65 kg of fluff pulp fibers are crushed and opened, and then subjected to plasma treatment. The treatment conditions are: power 25 W, pressure 35 Pa, time 4 s; Step 5: Add 15 kg of modified soy protein; Step 6: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 70%, forming a dust-free paper fiber web; Step 7: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 19N / mm; Step 8: Send it to the hot melt oven net and heat it at 150°C for consolidation; Step 9: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Comparative Example 3 The difference between this embodiment and embodiment 4 is that soybean protein is directly used, specifically: A method for preparing high-strength dust-free paper, measured by weight, comprises the following steps: Step 1: Take 25kg of hot-melt ultra-short fibers for opening, and 65kg of fluff pulp fibers for opening after crushing, and then treat with plasma. The treatment conditions are: power 25W, pressure 35Pa, time 4s; Step 2: Add 15kg soy protein and 4kg micro-silica gel to mix. Micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g; Step 3: sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net. The forming humidity is 70%, forming a dust-free paper fiber web; Step 4: compact the dust-free paper fiber web at a compaction temperature of 85°C and a pressure of 19N / mm; Step 5: Send it to the hot melt oven net and heat it at 150°C to solidify it; Step 6: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper. Thickness measurement: Use a digital fabric thickness meter with an accuracy of 0.01mm. According to the standard, the pressure is 0.5kPa (the pressure foot area is 2500mm 2 , pressure of 125cN), randomly sample 6 points in the full-width dust-free paper to test its average thickness; Determination of breaking strength (i.e. tensile strength): using an electronic fabric strength tester, according to the standard, the sample size is 50mm×200mm (horizontal×vertical), the strength machine rising speed is 100mm / min, and randomly sample 6 points in the full-width dust-free paper to test its average breaking strength. The test results are shown in Table 1 below: Table 1 The above embodiments are intended to provide a clear and complete description of the technical solution, and are partial implementations of the present invention, rather than all implementations. However, the implementations of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations or simplifications that do not deviate from the spirit and principle of the present invention shall be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing high-strength dust-free paper, characterized in that: By weight, the method comprises the following steps: Step 1: Take 20-30 parts of hot-melt short fibers for opening, and 50-70 parts of fluff pulp fibers for opening after crushing, and then treat with plasma; Step 2: Add 10-15 parts of modified soy protein and 2-5 parts of micro-silica gel and mix; Step 3: Sent to the former, broken up through the air inlet and kept floating, and under the action of vacuum suction under the forming net, it falls through the forming head and is adsorbed onto the forming net to form a dust-free paper fiber web; Step 4: compacting the dust-free paper fiber web; Step 5: Send it to the hot melt oven net and heat it at a temperature of 125-160°C for consolidation; Step 6: After the cooling system, surface treatment and shaping are carried out to obtain high-strength dust-free paper.

2. The method for preparing high-strength dust-free paper according to claim 1, characterized in that: The plasma treatment conditions are: power of 10-30W, pressure of 30-40Pa, and time of 2-5s.

3. The method for preparing high-strength dust-free paper according to claim 1, characterized in that: The preparation method of the modified soy protein is as follows: S1: Mix 4-5g soy protein, 5g sodium chloroacetate and 10g water, add 4.5g 45% NaOH solution, heat to 40℃ for 2h, and then quickly heat to 70℃ for 2h; S2: ultrafiltration with an ultrafiltration membrane, concentrated to 20 mL, and then diluted to 200 mL with deionized water, and repeated ultrafiltration 3 times to obtain a carboxymethylated soybean protein solution; S3: Slowly add 7-8 mL of epichlorohydrin to the carboxymethylated soy protein solution in a 60°C water bath and react for 2-3 hours to obtain a modified soy protein solution; S4: filtering and drying to obtain modified soy protein.

4. The method for preparing high-strength dust-free paper according to claim 3, characterized in that: The molecular weight cut-off of the ultrafiltration membrane in S2 is 10 kDa.

5. The method for preparing high-strength dust-free paper according to claim 1, characterized in that: The micro-silica gel has a three-dimensional network structure and a specific surface area of ​​1100-1200m 2 / g.

6. The method for preparing high-strength dust-free paper according to claim 1, characterized in that: The molding humidity in step 3 is 60-75%.

7. The method for preparing high-strength dust-free paper according to claim 1, characterized in that: In step 4, the compaction temperature is 80-90° C. and the pressure is 15-20 N / mm.

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