Environment-friendly paper bag and production process and application thereof

Abstract

The invention discloses an environment-friendly paper bag and a production process and application thereof, and belongs to the technical field of paper bag preparation, the environment-friendly paper bag comprises base paper, and a wet strength agent accounting for 3%-6% of the total mass of oven dry pulp, aluminum sulfate accounting for 7%-8% of the total mass of the oven dry pulp and cationic rosin size accounting for 2.5%-3% of the total mass of the oven dry pulp are added into the base paper; the wet strength agent is obtained by heating carboxyl-containing modified chitosan and formylated starch according to a mass ratio of 1: 1 under an acidic condition; the aldehyde content of the aldehyde starch is 43%-45%; the carboxyl-containing modified chitosan is one of carboxymethylation modified chitosan and anhydride acylation modified chitosan. The prepared environment-friendly paper bag is good in air permeability, has good wet strength, can resist rain wash, further has certain antibacterial property, prevents diseases and insect pests, reduces pesticide residues and can be used as a fruit cultivation paper bag.

Description

Technical Field

[0001] This invention belongs to the field of paper bag manufacturing technology, specifically relating to an environmentally friendly paper bag and its production process and application. Background Technology

[0002] In fruit cultivation, bagging technology has become a widely used technique because it can improve the coloring, cleanliness, and integrity of the fruit. However, paper bags generally have limitations in terms of poor mechanical properties, requiring the addition of reinforcing agents to improve their strength. Furthermore, due to the influence of climatic conditions such as wind and rain during the fruit growing season, the paper bags used for preparing the fruit bags must have good wet strength.

[0003] Patent CN104313947A discloses a method for preparing breathable and waterproof fruit-growing bagging paper. The method involves pulping, beating, grinding, refining, mixing, and forming a mesh from softwood and hardwood pulp to obtain wood pulp paper. A waterproof and highly breathable emulsion is then uniformly coated onto the wood pulp paper, resulting in a breathable and waterproof fruit-growing bagging paper with high breathability and water resistance. This increases paper strength and significantly improves paper utilization, making it suitable for various fruits. However, this method uses urea-formaldehyde resin as a wet strength agent. This reinforcing agent is petroleum-based, and the large amount used in fruit-growing bags, coupled with the environmental impact of petroleum-based reinforcing agents, contributes to environmental stress. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly paper bag, its production process, and its application to solve the problem of poor paper bag strength.

[0005] The objective of this invention can be achieved through the following technical solutions: An environmentally friendly paper bag includes a base paper containing 3%-6% wet strength agent, 7%-8% aluminum sulfate, and 2.5%-3% cationic rosin gum. The wet strength agent is obtained by heating carboxyl-modified chitosan and aldehyde-modified starch under acidic conditions at a mass ratio of 1:1. The aldehyde content of the aldehyde-based starch is 43%-45%; The carboxyl-modified chitosan is one of carboxymethylated chitosan and anhydride acylated chitosan.

[0006] Furthermore, the wet strength agent is prepared through the following steps: Carboxyl-modified chitosan and aldehyde-modified starch were added to an aqueous ethanol solution, the pH was adjusted to 6 h, and the mixture was heated and stirred at 70 °C. The wet strength agent was obtained by concentration under reduced pressure. The carboxyl-modified chitosan contains unreacted amino groups, which can react with aldehyde-modified starch to form Schiff bases.

[0007] Furthermore, the carboxymethylated modified chitosan is prepared by the following steps: Chitosan was alkalized, and then a mixture of chloroacetic acid and isopropanol was added. The mixture was reacted at 30°C for 4 hours. The reaction was stopped and the isopropanol was removed. After washing and drying, carboxymethylated modified chitosan was obtained. The ratio of chitosan to chloroacetic acid was 10 g: 0.005 mol.

[0008] Furthermore, the anhydride-acylated modified chitosan is prepared by the following steps: Chitosan was alkalized, acid anhydride was added, and the mixture was stirred and dispersed. Then, tetramethylpiperidine oxide was added, and the reaction continued. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH of the system to 10-12. The mixture was filtered, and the pH of the filtrate was adjusted to 3-4 with glacial acetic acid. The filtrate was then filtered again, and the residue was dried to obtain anhydride-modified chitosan. The amount of tetramethylpiperidine oxide added was 2% of the mass of chitosan. The acid anhydride was one of maleic anhydride, succinic anhydride, and 2-octenyl succinic anhydride. The ratio of chitosan to acid anhydride was 10 g: 0.005 mol.

[0009] Furthermore, the aldehyde-modified starch is prepared by the following steps: Starch was added to an aqueous solution of sodium periodate, the system was adjusted to acidity with hydrochloric acid, and the reaction was carried out at 30°C in the dark. After the reaction was completed, the starch was washed with ethanol and acetone and dried at 40°C to constant weight to obtain aldehyde-modified starch. The starch was either tapioca starch or sweet potato starch.

[0010] Furthermore, the pulp's freeness is 60-65. o SR.

[0011] Furthermore, the pulp comprises one or more of bleached softwood pulp, bleached hardwood pulp, and recycled pulp mixed in any proportion.

[0012] Furthermore, a production process for an environmentally friendly paper bag includes the following steps: At a stirring speed of 600 r / min, aluminum sulfate, cationic dispersed rosin gum, and wet strength agent are slowly added to the pulp in sequence. After the stirring speed is reduced to 200 r / min, the addition interval of each additive is 2 min. After thorough mixing and dispersion, pulp material is obtained. After papermaking and drying, base paper is obtained.

[0013] It also includes the application of an environmentally friendly paper bag in fruit cultivation paper bags.

[0014] The beneficial effects of this invention are: The environmentally friendly paper bags prepared by this invention have good air permeability, good wet strength and can withstand rain erosion. The environmentally friendly paper bags also have certain antibacterial properties, prevent pests and diseases, reduce pesticide residues, and can be used as fruit cultivation paper bags.

[0015] The raw materials for preparing paper bags using this invention are readily available, do not use large amounts of petroleum-based materials, do not put pressure on the environment, and can use recycled paper as raw material, making it environmentally friendly. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 Preparation of wet strength agent: Cassava starch was added to an aqueous solution of sodium periodate, and the pH of the system was adjusted to 3 with hydrochloric acid. The reaction was carried out at 30°C in the dark for 1.5 hours. After the reaction was completed, the starch was washed with ethanol and acetone and dried at 40°C to constant weight to obtain aldehyde-modified starch. The aqueous solution of sodium periodate was prepared by mixing sodium periodate and water at a mass ratio of 6.5 g: 50 mL; the mass ratio of sodium periodate to cassava starch was 6.5:12; the aldehyde content of the aldehyde-modified starch was determined to be 43%. According to the specified ratio, 10g of chitosan (CS, degree of deacetylation ≥95%, viscosity 100~200mPa·s), 12g of sodium hydroxide, and 100mL of isopropanol solvent were suspended in a flask and alkalized at -18℃ for 12h. 1g of chloroacetic acid was dissolved in 10mL of isopropanol and added dropwise to the above mixture over 30min. The reaction was carried out at 30℃ for 4h, and then the isopropanol was removed. The mixture was washed once each with 80% ethanol, 90% ethanol, and anhydrous ethanol for desalting and dehydration. Finally, the product was vacuum dried at 50℃ to obtain carboxymethylated modified chitosan.

[0018] Carboxymethylated chitosan and aldehyde-modified starch were added to a 50% (v / v) aqueous ethanol solution at a mass ratio of 1:1. The pH was adjusted for 6 hours, and the mixture was heated to 70°C and stirred for 1 hour. The wet strength agent was obtained by concentration under reduced pressure.

[0019] Example 2 Preparation of wet strength agent: Cassava starch was added to an aqueous solution of sodium periodate, and the pH of the system was adjusted to 3 with hydrochloric acid. The reaction was carried out at 30°C in the dark for 2 hours. After the reaction was completed, the starch was washed with ethanol and acetone and dried at 40°C to constant weight to obtain aldehyde-modified starch. The aqueous solution of sodium periodate was prepared by mixing sodium periodate and water at a mass ratio of 6.5 g: 50 mL; the mass ratio of sodium periodate to cassava starch was 6.5:12; the aldehyde content of the aldehyde-modified starch was determined to be 45%. According to the specified ratio, 10g of chitosan (CS, degree of deacetylation ≥95%, viscosity 100~200mPa·s) and 100mL of water were mixed and dispersed by stirring. 15g of sodium carbonate was added, and after the sodium carbonate dissolved, acid anhydride was added. After stirring for 30min, tetramethylpiperidine oxide was added, and the reaction was continued for 4h. After the reaction was completed, sodium hydroxide aqueous solution was added to adjust the pH of the system to 10-12. The mixture was filtered, and the pH of the filtrate was adjusted to 3-4 with glacial acetic acid. The filtrate was then filtered again, and the residue was dried to obtain anhydride-acylated chitosan. The amount of tetramethylpiperidine oxide added was 2% of the mass of chitosan. The acid anhydride was maleic anhydride; the ratio of chitosan to acid anhydride was 10g:0.005mol.

[0020] Anhydride-acylated chitosan and aldehyde-modified starch were added to a 50% (v / v) aqueous ethanol solution at a mass ratio of 1:1. The pH was adjusted for 6 hours, and the mixture was heated to 70°C and stirred for 1 hour. The wet strength agent was obtained by concentration under reduced pressure.

[0021] Comparative Example 1 Compared to Example 2, this comparative example uses untreated chitosan instead of anhydride-acylated chitosan to prepare a wet-strength agent. The remaining raw materials and preparation process are the same as in Example 2.

[0022] Example 3 Compared with Example 2, the acid anhydride used in this embodiment is succinic anhydride; the ratio of chitosan to succinic anhydride is 10g:0.005mol. The remaining raw materials and preparation process are the same as in Example 2.

[0023] Example 4 Compared with Example 2, the acid anhydride used in this example is 2-octenyl succinic anhydride; the ratio of chitosan to 2-octenyl succinic anhydride is 10g:0.005mol. The remaining raw materials and preparation process are the same as in Example 2.

[0024] Example 5 This embodiment provides a production process for environmentally friendly paper bags, including the following steps: A pulping degree of 65 o SR bleached softwood pulp, bleached hardwood pulp, and recycled wood pulp were mixed at a mass ratio of 8:2:5, and the mixed pulp concentration was adjusted to 2.5%. At a stirring speed of 600 r / min, the wet strength agent prepared by the method in Example 1 (3%-6% of the total oven-dry pulp mass), aluminum sulfate (7%-8% of the total oven-dry pulp mass), and cationic rosin gum (2.5%-3% of the total oven-dry pulp mass) were added slowly in sequence. After reducing the stirring speed to 200 r / min and ensuring thorough mixing and dispersion, the pulp was obtained. The interval between the additions was 2 minutes. Water was added to dilute the pulp to a concentration of approximately 0.3%, and the pulp was formed using a paper forming machine to achieve a basis weight of (40±1.0) g / m³. 2The paper sheets, wet paper sheets at 4kg / cm 2 Press under pressure for 2 minutes, then dry at 90°C for 4 minutes to obtain the base paper.

[0025] Adjust the proportions of raw materials in the slurry, and test the wet tensile index, antibacterial properties, and air permeability of the samples: Antibacterial properties were tested using the inhibition zone method. *Escherichia coli* was selected as the bacterial strain. The paper samples were cut into small round pieces with a diameter of 6 mm and sterilized under ultraviolet light for 1 hour. The diluted bacterial solution was then applied to a solid culture medium and spread evenly using a spreader. After the surface of the solid culture medium had slightly dried, the sterilized round samples were placed in the center of the four cross-shaped sections of the solid culture medium, inverted, and incubated at 37°C for 24 hours. The diameter of the inhibition zone was then measured.

[0026] Wet tensile index: Following the method for determining the tensile strength of paper and paperboard after immersion in water as specified in GB / T 465.2-2008, the paper samples were tested using a tensile testing machine, with an immersion time of 15 minutes. The results were finally converted into the wet tensile index, expressed in Nm·g. -1 express.

[0027] Air permeability: The test was conducted according to GB / T458-2008 using the Göller method. Paper samples were cut into 50 mm × 50 mm pieces, clamped in the instrument, and then the support frame was removed, allowing the inner cylinder to descend until it could float. The time taken for the inner cylinder to descend smoothly from 0 mL to 300 mL was recorded. The average value of the samples measured on both sides was taken. Results are expressed in μm / (Pa·s). Paper samples 1-6 were prepared based on Example 5, and relevant tests were conducted. The results are shown in Table 1 below: Table 1

[0028] Example 6 Compared with paper sample 3 in Example 5, the wet strength agent in this embodiment is replaced with the wet strength agent prepared in Example 2, while the other raw materials and preparation conditions are the same as those in the paper sample preparation in Example 3.

[0029] Example 7 Compared with paper sample 3 in Example 5, the wet strength agent in this embodiment is replaced with the wet strength agent prepared in Example 3, while the other raw materials and preparation conditions are the same as those in the paper sample preparation in Example 3.

[0030] Example 8 Compared with paper sample 3 in Example 5, the wet strength agent in this embodiment is replaced with the wet strength agent prepared in Example 4, while the other raw materials and preparation conditions are the same as those in the paper sample preparation in Example 3.

[0031] Comparative Example 2 Compared with paper sample 3 in Example 5, the wet strength agent in this embodiment is replaced with the wet strength agent prepared in Comparative Example 1, while the other raw materials and preparation conditions are the same as those in the paper sample of Example 3.

[0032] The wet tensile index, antibacterial properties, and air permeability of the paper samples were measured, and the results are shown in Table 2 below: Table 2

[0033] The test results show that the paper sample prepared in this embodiment of the invention has better wet strength than Comparative Example 2 (which uses aldehyde-modified starch and chitosan as raw materials to prepare a wet strength agent). The added wet strength agent is made from starch aldehyde and chitosan with antibacterial properties. A Schiff base reaction occurs between starch aldehyde and chitosan, consuming some aldehyde groups, which leads to a decrease in the degree of cross-linking inside the paper sample. In this invention, by treating chitosan and introducing carboxyl groups, the consumption of aldehyde groups is reduced on the one hand, and carboxyl groups are introduced on the other hand, which improves the strength of the hydrogen bond cross-linking network inside the paper sample, thereby improving the strength of the paper sample. Compared with paper sample 3 in Example 5, the wet strength agent in Example 8 changed the type of acid anhydride and introduced hydrophobic alkyl long chains, which has a promoting effect on improving the air permeability of the paper sample. The prepared environmentally friendly paper bag has high air permeability and strong wet strength, and can be well applied to fruit-growing paper bags.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly paper bag, characterized in that, The base paper contains 3%-6% wet strength agent, 7%-8% aluminum sulfate, and 2.5%-3% cationic rosin gum. The wet strength agent is obtained by heating carboxyl-modified chitosan and aldehyde-modified starch under acidic conditions at a mass ratio of 1:

1. The aldehyde content of the aldehyde-based starch is 43%-45%; The carboxyl-modified chitosan is one of carboxymethylated chitosan and anhydride acylated chitosan.

2. The environmentally friendly paper bag according to claim 1, characterized in that, The wet strength agent is prepared through the following steps: Carboxyl-modified chitosan and aldehyde-modified starch were added to an aqueous ethanol solution, the pH was adjusted to 6 h, and the mixture was heated and stirred at 70 °C. The wet strength agent was obtained by concentration under reduced pressure.

3. The environmentally friendly paper bag according to claim 1, characterized in that, The carboxymethylated modified chitosan is prepared through the following steps: Chitosan was alkalized, and a mixture of chloroacetic acid and isopropanol was added. The mixture was reacted at 30°C for 4 hours. The reaction was stopped and the isopropanol was removed. After washing and drying, carboxymethylated modified chitosan was obtained. The ratio of chitosan to chloroacetic acid was 10 g: 0.005 mol.

4. The environmentally friendly paper bag according to claim 1, characterized in that, The anhydride-acylated modified chitosan is prepared through the following steps: Chitosan was alkalized, and anhydride was added and stirred for 30 min to disperse it. Then, tetramethylpiperidine oxide was added, and stirring was continued for 4 h. After that, sodium hydroxide aqueous solution was added to adjust the pH of the system to 10-12, and the mixture was filtered. The pH of the filtrate was adjusted to 3-4 with glacial acetic acid, and the mixture was filtered again. The filter residue was dried to obtain anhydride-modified chitosan. The amount of tetramethylpiperidine oxide added was 2% of the mass of chitosan. The anhydride was one of maleic anhydride, succinic anhydride, and 2-octenyl succinic anhydride. The ratio of chitosan to anhydride was 10 g: 0.005 mol.

5. The environmentally friendly paper bag according to claim 1, characterized in that, The aldehyde-modified starch is prepared by the following steps: Starch was added to an aqueous solution of sodium periodate, the system was adjusted to acidity with hydrochloric acid, and the reaction was carried out at 30°C in the dark. After the reaction was completed, the starch was washed with ethanol and acetone and dried at 40°C to constant weight to obtain aldehyde-modified starch. The starch was either tapioca starch or sweet potato starch.

6. The production process of an environmentally friendly paper bag according to claim 1, characterized in that, Includes the following steps: At a stirring speed of 600 r / min, aluminum sulfate, cationic dispersed rosin gum, and wet strength agent are slowly added to the pulp in sequence, with an interval of 2 min between each addition. After the stirring speed is reduced to 200 r / min, the pulp is obtained after thorough mixing and dispersion. The pulp is then processed and dried to obtain the base paper.

7. The production process of an environmentally friendly paper bag according to claim 6, characterized in that, The pulp freeness is 60-65. o SR.

8. The production process of an environmentally friendly paper bag according to claim 6, characterized in that, The pulp comprises one or more of bleached softwood pulp, bleached hardwood pulp, and recycled pulp, mixed in any proportion.

9. Application of an environmentally friendly paper bag in fruit cultivation paper bags.

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