Method for preparing coffee filter paper by taking coffee grounds as filler

Abstract

The invention discloses a method for preparing coffee filter paper by taking coffee grounds as filler, and belongs to the technical field of papermaking. The preparation method comprises the following steps: drying, crushing and sieving coffee grounds, and carrying out ultrasonic dispersion on sieved powder to prepare coffee grounds suspension; the method comprises the following steps: defibering wood pulp, mixing the defibering wood pulp with a wet strength agent solution, a retention and drainage aid and a coffee residue suspension, and then carrying out papermaking, squeezing, drying and water balance treatment to obtain the coffee filter paper. The waste coffee grounds are used as the functional filler, so that the efficient utilization of wastes is realized, the phenomena of resource waste and environmental pollution are reduced, the process is simple, and the preparation cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing coffee filter paper with coffee grounds as filler, belonging to the technical field of papermaking. BACKGROUND

[0002] Coffee filter paper is a filter material made of cellulose with many fine pores, which can filter out solid impurities and oily components in coffee, so that the coffee tastes more mellow and refreshing, and the bitterness is reduced. Coffee filter paper is a disposable product, which is an indispensable consumable in hand-brewed coffee, drip coffee machine and other brewing methods. It is convenient to use and does not need to be cleaned after brewing, so most coffee shops use coffee filter paper to brew coffee. Chinese patent No. CN110886121A provides a coffee filter paper and a preparation method thereof, but the preparation process is complex, the inner layer, the middle layer and the outer layer are obtained by compression roller compounding and shaping to obtain the coffee filter paper, and silica, polyacrylate, hydroxymethyl cellulose, polysiloxane, amylase, etc. are added, which has high cost and is difficult to realize real industrial application.

[0003] Therefore, it is urgent to find a coffee filter paper preparation method with simple process and low cost. The coffee filter paper prepared with coffee grounds as filler improves the added value of coffee grounds, reduces resource waste, and at the same time achieves the effect of improving the taste and flavor of coffee. The present application realizes the high value-added utilization of coffee grounds, reduces the pollution to the environment, and meets the requirements of high value-added utilization of biomass resources and economic green and sustainable development. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a coffee filter paper preparation method with simple process and low cost, which has the advantages of simple process, low cost, green and sustainable development, etc., and solves the problem of complex preparation process.

[0005] The present application aims to provide a method for preparing coffee filter paper with coffee grounds as filler, which specifically comprises the following steps: (1) The collected coffee grounds are dried at 50-60°C, then crushed by a ball mill, and sieved to obtain coffee ground powder; the coffee ground powder is dispersed in water, and ultrasonic treatment is carried out in a 500 W ultrasonic cleaner at room temperature for 20 min to prepare a coffee ground suspension.

[0006] (2) The wood pulp fiber (including coniferous wood pulp and broad-leaved wood pulp) with a beating degree of 15-25 ºSR is defibrated to obtain a uniform wood pulp suspension.

[0007] (3) adding a wet strength agent solution and a retention and drainage agent into the wood pulp suspension, defibrating, and mixing with the coffee grounds suspension, wherein the wet strength agent is at least one of chitosan, urea-formaldehyde resin, polyamide polyamine epichlorohydrin, and the retention and drainage agent is at least one of cationic starch, carboxymethyl cellulose, and sodium alginate.

[0008] (4) papermaking the mixed pulp, then pressing for 25-35 s under a pressure of 0.3-0.5 Mpa, drying for 10-20 min at a temperature of 105℃, and finally performing moisture balance treatment for 3-5 h under a temperature of 23-27℃ and a relative humidity of 40%-50% to prepare coffee filter paper with a basis weight of 30-50 g / m².

[0009] Preferably, the mesh number of the screen in step (1) is 200-400.

[0010] Preferably, the concentration of the coffee grounds suspension in step (1) is 1-3 g / L.

[0011] Preferably, the wet strength agent in step (3) is at least one of chitosan, urea-formaldehyde resin, polyamide polyamine epichlorohydrin, and the concentration is 0.2-0.4 g / L.

[0012] Preferably, the ratio of the absolutely dry wood pulp to the wet strength agent solution in step (3) is 1 g:100 mL-1 g:300 mL.

[0013] Preferably, the retention and drainage agent in step (3) is at least one of cationic starch, carboxymethyl cellulose, and sodium alginate, and the mass ratio of the absolutely dry wood pulp to the retention and drainage agent is 1 g:0.05 g-1 g:0.09 g.

[0014] Preferably, the wood pulp in step (2) comprises mixed pulp of coniferous wood pulp and broad-leaved wood pulp, and the beating degree is 15-25 ºSR.

[0015] Preferably, the pH value of the chitosan solution in step (3) is adjusted to 5.5-6.5. If the pH value of the chitosan solution is too low, the hydrogen bonding between chitosan and fibers will be affected, resulting in low strength of the coffee filter paper; if the pH value is too high, the solubility of chitosan will decrease, and the proportion of the wet strength agent will be too low to affect the strength of the coffee filter paper; preferably, the pH value of the chitosan solution is adjusted to 6.

[0016] Preferably, the basis weight of the coffee filter paper in step (4) is 30-50 g / m².

[0017] The beneficial effects of the present application are as follows: (1) Efficient utilization of waste and cost reduction: Coffee grounds are used as functional fillers, which are low in price and high in yield, and can be converted into coffee filter paper with high added value. The addition amount can reach 35%, effectively reducing the amount of wood pulp and production cost, and reducing environmental pollution caused by improper disposal such as landfill and incineration. Coffee grounds will fill in the fiber pores, thereby reducing the pore size of the filter paper, filtering out most of the coffee bean particles during coffee filtration, reducing the problem of coffee taste, and improving the taste and flavor of coffee.

[0018] (2) Excellent mechanical properties: In the preparation method of the coffee filter paper provided by the application, chitosan is added as a wet strength agent. The chitosan is adsorbed on the negatively charged fibers through electrostatic combination and hydrogen bond action, and can bridge between the fibers, effectively improving the tensile strength and tear resistance of the coffee filter paper.

[0019] (3) Simple and green process: The reagents used in the preparation process are environmentally friendly and can be degraded under natural conditions, reducing wastewater discharge and treatment cost. The preparation process is simple and highly feasible, with stable parameters and potential for large-scale industrial production. DETAILED DESCRIPTION

[0020] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with specific examples.

[0021] Example 1 A method for preparing coffee filter paper using coffee grounds as filler, specifically comprising the following steps: 0.1 g of coffee grounds (10%wt) passing through a 200 mesh sieve was weighed, ultrasonically cleaned in a 500 W ultrasonic cleaner at room temperature for 20 min, and uniformly dispersed to obtain a coffee ground suspension.

[0022] 0.06 g of chitosan was dissolved in 20 mL of 1% acetic acid solution, diluted to 200 mL, and the pH value was adjusted to 6 for standby. 0.24 g of softwood pulp with a beating degree of 15 ºSR (calculated on an absolute dry basis), 0.55 g of hardwood pulp with a beating degree of 15 ºSR (calculated on an absolute dry basis), and a retention and drainage aid were weighed, added to the above chitosan solution, and defibrated in a fiber standard disintegrator. After mixing with the above coffee ground suspension, papermaking, pressing (pressure 0.4 Mpa, pressing time 30 s), drying and molding (drying temperature 105°C, drying time 15 min), and balancing the moisture (temperature 25°C, relative humidity 50%, time 4 h), coffee filter paper was obtained.

[0023] The addition amount of the retention and drainage aid in Example 1 was 0.05 g of cationic starch, 0.05 g of carboxymethyl cellulose, 0.05 g of cationic starch, and 0.05 g of carboxymethyl cellulose, respectively, and the performance is shown in Table 1: Table 1: Tensile strength and tear resistance of coffee filter paper with different retention aids and filter aid dosages Table 1 shows that the amount of retention and filtration aids added affects the product performance. The combined addition of cationic starch and carboxymethyl cellulose (CMC) yields better results because they are complementary in terms of charge properties, fiber binding mechanisms, and filtration performance, synergistically improving the mechanical strength and retention rate of the filter paper. A significant synergistic effect exists between them and coffee grounds: cationic starch increases the retention rate of coffee grounds, and CMC coats the coffee grounds and improves filtration performance. The combined effect of these three factors allows the coffee filter paper to maintain good strength and filtration performance even with high filler content, achieving high-value utilization of coffee grounds and optimization of filter paper performance.

[0024] Example 2 A method for preparing coffee filter paper using coffee grounds as filler includes the following steps: Weigh 0.1 g of coffee grounds (10%wt) that have passed through a 200-mesh sieve, and sonicate them in a 500 W ultrasonic cleaner at room temperature for 20 minutes to disperse them evenly and obtain a coffee grounds suspension.

[0025] A certain amount of chitosan was weighed and dissolved in 20 mL of 1% acetic acid solution, diluted to 200 mL, and the pH was adjusted to 6 for later use. 0.05 g of cationic starch and 0.05 g of carboxymethyl cellulose were weighed separately from softwood pulp (15ºSR, oven-dry), hardwood pulp (15ºSR, oven-dry), and added to the chitosan solution. The mixture was then disintegrated in a fiber standard dissociator and mixed with the coffee grounds suspension. The mixture was then subjected to papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0026] In Example 2, the amounts of chitosan added were 0.04 g, 0.06 g, and 0.08 g, respectively, and their properties are shown in Table 2. Table 2: Tensile strength and tear resistance of coffee filter paper with different chitosan addition amounts Table 2 shows that the amount of chitosan added affects the performance of the product. As the amount of chitosan added increases, its tensile strength and tear resistance are better. This is because there are many amino and hydroxyl groups on the chitosan molecular chain, which can serve as positive charge centers and hydrogen bond centers, respectively. They can then be adsorbed onto the negatively charged fibers through electrostatic bonding and hydrogen bonding, and can also bridge between fibers, thereby improving the strength of the coffee filter paper.

[0027] Example 3 A method for preparing coffee filter paper using coffee grounds as filler includes the following steps: Weigh 0.1 g of coffee grounds (10%wt) that have passed through a 200-mesh sieve, and sonicate them in a 500 W ultrasonic cleaner at room temperature for 20 minutes to disperse them evenly and obtain a coffee grounds suspension.

[0028] 0.06 g of chitosan was dissolved in 20 mL of 1% acetic acid solution, diluted to 200 mL, and the pH was adjusted to 6 for later use. 0.05 g of cationic starch and 0.05 g of carboxymethyl cellulose were weighed separately from softwood pulp (15 ºSR, oven-dry), hardwood pulp (15 ºSR, oven-dry), and chitosan solution. The mixture was then dissolved in a fiber standard dissociator and mixed with the coffee grounds suspension. The mixture was then subjected to papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0029] Example 3 The properties of the medium coniferous wood added at 10% and 20% are shown in Table 3: Table 3: Tensile strength and tear resistance of coffee filter paper with different amounts of coniferous wood added Table 3 shows that the amount of coniferous wood added affects the strength of the filter paper. As the amount of coniferous wood added increases, its tensile strength and tear resistance are better. This is because the secondary wall outer layer of hardwood fiber is thicker, which makes it more resistant to mechanical action and less prone to fission during pulping, resulting in lower paper strength. Coniferous wood pulp is more prone to fission, resulting in higher paper strength. Adding an appropriate amount of coniferous wood helps to improve the strength of the filter paper.

[0030] Example 4 A method for preparing coffee filter paper using coffee grounds as filler includes the following steps: Weigh 0.3 g of coffee grounds (30% wt) that have passed through a 200-mesh sieve, and sonicate them at room temperature for 20 minutes in a 500 W ultrasonic cleaner to obtain a coffee grounds suspension.

[0031] Weigh 0.06 g of chitosan and dissolve it in 20 mL of 1% acetic acid solution. Dilute to 200 mL and adjust the pH to 6 for later use. Weigh 0.11 g of softwood pulp (on an oven-dry basis) with different degrees of beating, 0.43 g of hardwood pulp (on an oven-dry basis) with different degrees of beating, 0.05 g of cationic starch, and 0.05 g of carboxymethyl cellulose. Add them to the chitosan solution and dissolve them in a fiber standard dissociator. Mix with the coffee grounds suspension and then perform papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0032] The freeness of the wood pulp in Example 4 were 18ºSR, 20ºSR, and 25ºSR, and their properties are shown in Table 4. Table 4: Tensile strength and tear resistance of coffee filter paper with different beating degrees Table 4 shows that the beating degree of wood pulp affects the strength of filter paper. As the beating degree increases, its tensile strength and tear resistance are better. This is because increasing the beating degree reduces the average length of the fibers, increases the number of fine fibers, promotes the bonding of hydrogen bonds between fibers, and improves the bonding force between fibers, thereby increasing the strength of coffee filter paper.

[0033] Comparative Example 1 Weigh 0.11 g of softwood pulp (on an oven-dry basis) with a freeness of 15 ºSR and 0.44 g of hardwood pulp (on an oven-dry basis) with a freeness of 15 ºSR. After decomposition in a fiber standard decomposer, papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and forming (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) are carried out to obtain commercial coffee filter paper.

[0034] Comparative Example 2 Weigh 0.2 g of coffee grounds (20% wt) that have passed through a 200-mesh sieve, and sonicate them in a 500 W ultrasonic cleaner at room temperature for 20 min to disperse them evenly and obtain a coffee grounds suspension.

[0035] Weigh 0.06 g of chitosan and dissolve it in 20 mL of 1% acetic acid solution. Dilute to 200 mL and adjust the pH to 6 for later use. Weigh 0.13 g of softwood pulp (freezing degree 15 ºSR), 0.52 g of hardwood pulp (freezing degree 15 ºSR), 0.05 g of cationic starch, and 0.05 g of carboxymethyl cellulose. Add them to the chitosan solution and dissolve them in a fiber standard dissociator. Mix with the coffee grounds suspension and then perform papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0036] Comparative Example 3 Weigh 0.3 g of coffee grounds (30% wt) that have passed through a 200-mesh sieve, and sonicate them at room temperature for 20 minutes in a 500 W ultrasonic cleaner to obtain a coffee grounds suspension.

[0037] Weigh 0.06 g of chitosan and dissolve it in 20 mL of 1% acetic acid solution. Dilute to 200 mL and adjust the pH to 6 for later use. Weigh 0.11 g of softwood pulp (freezing degree 15 ºSR), 0.44 g of hardwood pulp (freezing degree 15 ºSR), 0.05 g of cationic starch, and 0.05 g of carboxymethyl cellulose. Add them to the chitosan solution and dissolve them in a fiber standard dissociator. Mix with the coffee grounds suspension and then perform papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0038] Comparative Example 4 Weigh 0.35 g of coffee grounds (30% wt) that have passed through a 200-mesh sieve, and sonicate them in a 500 W ultrasonic cleaner at room temperature for 20 minutes to disperse them evenly and obtain a coffee grounds suspension.

[0039] Weigh 0.06 g of chitosan and dissolve it in 20 mL of 1% acetic acid solution. Dilute to 200 mL and adjust the pH to 6 for later use. Weigh 0.10 g of softwood pulp (freezing degree 15 ºSR), 0.39 g of hardwood pulp (freezing degree 15 ºSR), 0.05 g of cationic starch, and 0.05 g of carboxymethyl cellulose. Add them to the chitosan solution and dissolve them in a fiber standard dissociator. Mix with the coffee grounds suspension and then perform papermaking, pressing (pressure 0.4 MPa, pressing time 30 s), drying and shaping (drying temperature 105℃, drying time 15 min), and moisture equilibration (temperature 25℃, relative humidity 50%, time 4 h) to obtain coffee filter paper.

[0040] The performance of Comparative Examples 1-4 is shown in Table 4: Table 4: Tensile strength and tear resistance of coffee filter paper Furthermore, by optimizing conditions such as the proportion of coniferous wood and the amount of coffee grounds added, this invention significantly improves the tensile strength and tear resistance of the coffee filter paper. Compared with commercial coffee filter paper, the tensile strength can be increased by up to 83.33%, and the tear resistance by 64.27%. As the amount of coffee grounds added increases, the strength of the coffee filter paper tends to decrease. In Comparative Example 2, when the amount of coffee grounds added is 20%, the tensile strength is 0.48 KN / m, and the tear resistance is 547.20 mN, both of which are higher than the strength of the coffee filter paper in Comparative Example 1. This effectively reduces the amount of wood pulp used and achieves the best balance between cost and performance.

[0041] In summary, the coffee filter paper preparation method provided by this invention uses coffee grounds as a filler, which is inexpensive and has a high yield, transforming it into high-value-added coffee filter paper. The addition amount can reach 20%, effectively reducing wood pulp usage, lowering production costs, and reducing environmental pollution caused by inappropriate disposal methods such as landfill and incineration. The addition of chitosan as a wet strength agent allows it to be adsorbed onto negatively charged fibers through electrostatic bonding and hydrogen bonding, and it can also bridge between fibers, effectively improving the tear strength and tensile strength of the coffee filter paper. Its mechanical properties meet the requirements for coffee filter paper use and can effectively replace current commercial coffee filter paper. The coffee filter paper preparation process is simple and feasible, and the reagents used are green and environmentally friendly, showing potential for industrial application.

Claims

1. A method of making coffee filter paper with coffee grounds as filler, characterized by, The method comprises the following steps: (1) drying and crushing coffee grounds to obtain coffee ground powder, and dispersing the coffee ground powder in water to obtain a uniform coffee ground suspension by ultrasonic treatment; (2) defibrating wood pulp fibers to obtain a wood pulp suspension; (3) adding a wet strength agent solution and a retention and drainage aid to the wood pulp suspension, and mixing the defibrated wood pulp suspension with the coffee ground suspension; and 2. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, (4) papermaking, pressing, drying and moisture balancing the mixed pulp to obtain the coffee filter paper.

3. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, The screen mesh size of the screening treatment is 200-400 mesh.

4. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, The concentration of the coffee ground suspension is 1-3 g / L.

5. The coffee filter manufacturing method according to claim 4, wherein The wet strength agent is at least one of chitosan, urea-formaldehyde resin, polyamide polyamine epichlorohydrin, and the concentration is 0.2-0.4 g / L.

6. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, The ratio of the absolutely dry wood pulp to the wet strength agent solution is 1 g:100 mL-1 g:300 mL.

7. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, The retention and drainage aid is at least one of cationic starch, carboxymethyl cellulose and sodium alginate, and the mass ratio of the absolutely dry wood pulp to the retention and drainage aid is 1 g:0.06 g-1 g:0.09 g.

8. The method for preparing coffee filter paper using coffee grounds as filler according to claim 1, characterized in that, The wood pulp fibers comprise mixed pulp of coniferous wood pulp and broad-leaved wood pulp, and the beating degree is 15-25 ºSR. The addition amount of the coffee grounds is 10%-35% of the total mass of the pulp, based on the total mass of the absolutely dry substances.

9. The coffee filter paper prepared by the method of any one of claims 1-8.

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