Adsorptive antibacterial filter paper for food and preparation method thereof

Abstract

The invention discloses adsorptive antibacterial filter paper for food and a preparation method thereof, and relates to the field of filter paper. The paper is prepared from the following raw materials in parts by weight: 60-80 parts of paper pulp fiber, 15-30 parts of inorganic filler, 5-10 parts of chitosan and 1-2 parts of papermaking additive. Chitosan with high deacetylation degree and paper pulp fibers are blended, inorganic filler with adsorbability is added, uniform blended paper pulp is prepared, and finally the filter paper is manufactured through the papermaking processes of forming, dewatering, squeezing, drying and the like. The chitosan and the inorganic filler with adsorbability are added into the filter paper, so that the mechanical strength and the wet strength of the filter paper can be ensured, and the adsorption capacity and the antibacterial property of the filter paper on harmful substances such as pigments and heavy metals in food can be improved.

Description

Technical Field

[0001] The present invention relates to the field of filter paper, and particularly to an adsorbent antibacterial filter paper for food and a preparation method thereof. Background Art

[0002] In recent years, driven by multiple factors such as market demand, technological progress, and environmental protection requirements, the filter paper industry has shown a rapid development trend. Technological progress, environmental protection requirements, and people's pursuit of high-quality food have put forward higher requirements for the performance of filter paper for food.

[0003] With the continuous expansion of the food production scale, higher requirements are placed on the mechanical strength and filtration efficiency of filter paper in the filtration process of food production. Existing filter papers improve the strength of filter paper by using higher-strength chemical fibers or introducing nanofibers or ultrafiltration membranes, but this method leads to the inability of the filter paper to degrade in the environment, causing environmental pollution and increasing production costs.

[0004] Since food filter paper is mainly applied to the food processing industry, higher safety requirements are imposed on it. How to manufacture filter paper with high strength, high safety, and environmental protection using safe and environmentally friendly fiber materials and various additives including adhesives, dispersants, and antibacterial agents is a problem that needs to be solved.

[0005] Patent CN111501414B discloses a preparation method of antibacterial filter paper. The antibacterial filter paper ensures a stable antibacterial effect of the antibacterial agent in the filter paper by adding antibacterial fillers in the manufacturing process of the antibacterial filter paper. However, this filter paper contains quaternary ammonium salts and has quaternary ammonium salt-like antibacterial agents, which have acute toxicity and are not suitable for food filter paper. In the production process of food, how to efficiently and safely remove harmful substances including pigments, bacteria, and heavy metal ions contained in food is a problem. There may be problems of safety and excessive chemical reagents through chemical methods. At this time, filtration can be selected to remove bacteria, and adsorption can be used to remove pigments and heavy metal ions. However, after the filter paper is used for a long time, the filter paper will be contaminated by bacteria and cannot be used. Therefore, the antibacterial performance of the filter paper itself also needs to be considered.

[0006] In summary, filter paper for food should have high mechanical strength, antibacterial performance, adsorption performance, good safety, and be able to degrade naturally and the degradation products should be non-polluting to the environment. Summary of the Invention

[0007] Aiming at the problems of insufficient safety and antibacterial performance of existing food filter paper, the present invention provides an adsorbent antibacterial filter paper for food and a preparation method thereof.

[0008] The specific technical solution of the present invention is as follows: an adsorbent antibacterial filter paper for food; it is prepared from the following raw materials in parts by weight: 60-80 parts of pulp fiber, 15-30 parts of porous inorganic filler, 5-10 parts of chitosan, and 10-2 parts of papermaking additive.

[0009] Preferably, the pulp fiber is selected from one or more of softwood pulp, sulfite pulp, and cotton pulp.

[0010] Softwood pulp, sulfite pulp, and cotton pulp fibers are slender and uniform, have high strength and interweaving ability, are suitable for manufacturing high-strength filter paper, and these pulp fibers are all natural fibers, harmless to the human body and can be naturally degraded.

[0011] Preferably, the porous inorganic filler is selected from one or more of activated carbon, nano-silica, diatomaceous earth, and bentonite.

[0012] The above-mentioned inorganic filler can improve the filtration accuracy, adsorption capacity and mechanical strength of the filter paper, and itself has stable chemical properties, is non-toxic to the human body, and has no pollution to the environment after the filter paper itself degrades.

[0013] Preferably, chitosan with a deacetylation degree of 90% is selected.

[0014] Chitosan is a natural polysaccharide with broad-spectrum antibacterial properties, which can effectively inhibit the growth of bacteria, fungi and molds. Therefore, the antibacterial performance of the filter paper is improved by the way of chitosan blending modification. The deacetylation degree of chitosan will directly affect the solubility, chemical activity, biocompatibility and functional properties (such as antibacterial property, adsorption property, etc.) of chitosan. When the deacetylation degree is high (>85%), chitosan has good solubility in dilute acids (such as acetic acid, hydrochloric acid), the content of free amino groups in the chitosan molecule is high, the reaction activity is strong, and the antibacterial performance is good. During the preparation process of the filter paper, chitosan and filter paper fibers are mixed to make chitosan evenly dispersed in the slurry, which can make the modification effect of chitosan stable. Through subsequent drying and curing, chitosan is stably combined with the filter paper. And chitosan can form a large number of hydrogen bonds with cellulose fibers to improve the strength and durability of the filter paper. The porous structure and adsorption property of chitosan itself can enhance the filtration efficiency and adsorption capacity of the filter paper, and cooperate with the adsorbent in the inorganic filler to improve the adsorption effect of the filter paper. Chitosan also has characteristics such as degradability and good biocompatibility, meeting the requirements of environmental protection.

[0015] Preferably, the papermaking additive is: wet strength agent, natural thickener, defoamer.

[0016] Preferably, the wet strength agent is selected as polyamide polyamine epichlorohydrin (PAE).

[0017] PAE has good stability at room temperature, does not contain harmful substances such as formaldehyde, belongs to an environmentally friendly wet strength agent and has good compatibility with other papermaking chemicals, and does not affect other properties of the paper. The epoxy group and amino group in the PAE molecule have high reactivity and can crosslink with the hydroxyl groups in cellulose fibers to form stable covalent bonds, thereby enhancing the wet strength of the paper. When in use, PAE can be directly added to the pulp without other treatment processes, which is convenient to use.

[0018] Preferably, the natural thickener is selected from one or more of gelatin, pectin, and starch.

[0019] The thickener can improve the viscosity, fiber dispersibility and formability of the pulp, thereby improving the uniformity, strength and filtration performance of the filter paper.

[0020] Preferably, the defoamer is selected from one or more of polydimethylsiloxane, modified silicone, a mixture of food-grade mineral oil and emulsifier, and food-grade fatty acid ester.

[0021] The above defoamer can ensure the stability of the production process and the uniformity of the filter paper. The composition and dosage of the defoamer need to meet the food safety standards and at the same time meet the requirements of the production process.

[0022] The preparation method of the adsorbent antibacterial filter paper for food use is as follows:

[0023] S1: Cook and beat the fiber raw material to make a uniform pulp slurry;

[0024] S2: Dissolve chitosan in dilute acid to make a chitosan solution;

[0025] S3: Mix the chitosan solution with the pulp slurry, and add inorganic fillers, wet strength agents, natural thickeners, and defoamers and stir evenly;

[0026] S4: Dilute the pulp and distribute the pulp onto the forming wire through a headbox to form a wet paper web;

[0027] S5: The wet paper web is made into a finished product through processes such as dehydration, compaction, drying, and hot pressing.

[0028] Preferably, the dilute acid is selected from one or more of acetic acid, citric acid, and acetic acid.

[0029] Ensure that the pulp concentration is uniform to facilitate the addition of other raw materials in subsequent processes. Chitosan has good solubility in dilute acetic acid, dilute citric acid, and dilute acetic acid and can be quickly dissolved.

[0030] Beneficial effects:

[0031] The adsorbent antibacterial filter paper for food of the present invention has high mechanical strength, excellent antibacterial properties and strong adsorption capacity. The raw materials of the filter paper are safe and stable, and the prepared filter paper can be naturally degraded without polluting the environment after degradation. The preparation process is simple and can be produced on a large scale.

[0032] The functional filter paper of the present invention reduces the pore size of the filter paper through steps such as selecting slender and uniform fibers, beating at a low consistency, adding wet strength agents, fillers and post-treatment. The antibacterial filter paper acts synergistically through two methods: physical filtration, adsorption and chemical antibacterial. It intercepts bacteria in food through filtration, and destroys the cell structure of bacteria through chitosan in the filter paper, inactivates spores and inhibits the growth of bacteria. Due to the excellent antibacterial properties of chitosan, bacteria are not easily generated on the filter paper itself after long-term use, which greatly reduces the bacterial content in the finally filtered food. Detailed implementation mode

[0033] In order to better illustrate the technical effects of the present invention, the following will analyze specific examples and comparative examples.

[0034] General example:

[0035] An adsorbent antibacterial filter paper for food; prepared from the following raw materials in parts by weight: 60 - 80 parts of pulp fiber, 15 - 30 parts of inorganic filler, 5 - 10 parts of chitosan, 0.5 - 1 part of wet strength agent, 1 - 2 parts of natural thickener, 0.03 - 0.06 part of defoamer.

[0036] The pulp fiber is selected from one or more of softwood pulp fiber, sulfite pulp fiber, and cotton pulp fiber.

[0037] The inorganic filler is selected from one or more of activated carbon, nano-silica, diatomite, and bentonite.

[0038] The degree of deacetylation of the chitosan is 75% - 95%.

[0039] The wet strength agent is polyamide polyamine epichlorohydrin (PAE).

[0040] The natural thickener is selected from one or more of gelatin, pectin, and starch.

[0041] The defoamer is selected from one or more of polydimethylsiloxane, modified silicone, a mixture of food-grade mineral oil and emulsifier, and food-grade fatty acid ester.

[0042] A preparation method of the above-mentioned adsorbent antibacterial filter paper for food, comprising the following steps:

[0043] S1: Cook the fiber raw material at 160 - 170 °C using the sulfate method, and beat the pulp with the assistance of ultrasonic waves to make a uniform pulp slurry with a concentration of 3% - 6%;

[0044] S2: Dissolve chitosan in 1% - 3% dilute acid to make a chitosan solution;

[0045] S3: Mix the chitosan solution with the pulp slurry, add inorganic fillers, wet strength agents, natural thickeners, and defoamers, and stir evenly;

[0046] S4: Dilute the pulp to a concentration of 0.1% - 1.5% to form a uniform suspension, and distribute the pulp onto the forming wire through a headbox to form a wet paper web;

[0047] S5: The wet paper web passes through a press roll, and the pressing pressure is adjusted within the range of 0.1 - 1 MPa according to the paper type for further dehydration and compaction; then it passes through a steam-heated dryer cylinder to remove the remaining moisture at 100 - 150 °C to dry the paper. Then, the smoothness and gloss of the paper are improved through a calender roll. Finally, the filter paper is placed in a hot press and treated at 100 - 200 °C and 0.5 - 1 MPa for 1 - 2 h.

[0048] In the above embodiment, the ultrasonic-assisted beating process in step S1 can improve the dispersibility and uniformity of pulp fibers, facilitating subsequent processing.

[0049] Example 1

[0050] An adsorbent and antibacterial filter paper for food; prepared from the following raw materials in parts by weight: 70 parts of softwood fiber, 22.5 parts of nano-silica, 7.5 parts of chitosan, 0.75 part of polyamide polyamine epichlorohydrin, 1.5 parts of xanthan gum, 0.045 part of polydimethylsiloxane.

[0051] The adsorbent and antibacterial filter paper for food is prepared through the following steps:

[0052] S1: Cook the softwood fiber raw material at 160 - 170 °C for 2 h using the sulfate method, and beat the pulp with the assistance of ultrasonic waves to make a uniform pulp slurry with a concentration of 3% - 6%;

[0053] S2: Dissolve chitosan with a deacetylation degree of 90% in 1% - 3% dilute acetic acid to make a chitosan solution;

[0054] S3: Mix the chitosan solution with the pulp slurry, add 22.5 parts by weight of nano-silica, 0.75 parts by weight of polyamide polyamine epichlorohydrin, 1.5 parts by weight of xanthan gum, 0.045 parts by weight of polydimethylsiloxane, and stir evenly;

[0055] S4: Dilute the pulp to a concentration of 0.1%-1.5% to form a uniform suspension, and distribute the pulp onto the forming wire through a headbox to form a wet paper web;

[0056] S5: The wet paper web passes through press rolls, and the pressing pressure is adjusted within the range of 0.1-1 MPa according to the paper type for further dehydration and compaction; then it passes through steam-heated dryer cylinders to remove the remaining moisture at 100-150 °C to dry the paper. Then, the smoothness and gloss of the paper are improved through calender rolls, and finally the filter paper is placed in a hot press and treated for 1-2 h under the conditions of 100-200 °C and 0.5-1 MPa.

[0057] Example 2

[0058] An adsorbent and antibacterial filter paper for food; it is prepared from the following raw materials in parts by weight: 60 parts of softwood fibers, 15 parts of nano-silica, 5 parts of chitosan, 0.5 part of polyamide polyamine epichlorohydrin, 1 part of xanthan gum, and 0.03 part of polydimethylsiloxane.

[0059] The adsorbent and antibacterial filter paper for food is prepared through the following steps:

[0060] S1: Cook the softwood fiber raw material with the sulfate method at 160-170 °C for 2 h, and beat the pulp with the assistance of ultrasonic waves to make a uniform pulp slurry with a concentration of 3%-6%;

[0061] S2: Dissolve chitosan with a deacetylation degree of 90% in 1%-3% dilute acetic acid to make a chitosan solution;

[0062] S3: Mix the chitosan solution with the pulp slurry, and add 15 parts by weight of nano-silica, 0.5 part by weight of polyamide polyamine epichlorohydrin, 1 part by weight of xanthan gum, and 0.03 part by weight of polydimethylsiloxane and stir evenly;

[0063] S4: Dilute the pulp to a concentration of 0.1%-1.5% to form a uniform suspension, and distribute the pulp onto the forming wire through a headbox to form a wet paper web;

[0064] S5: The wet paper web passes through press rolls, and the pressing pressure is adjusted within the range of 0.1-1 MPa according to the paper type for further dehydration and compaction; then it passes through steam-heated dryer cylinders to remove the remaining moisture at 100-150 °C to dry the paper. Then, the smoothness and gloss of the paper are improved through calender rolls, and finally the filter paper is placed in a hot press and treated for 1-2 h under the conditions of 100-200 °C and 0.5-1 MPa.

[0065] Example 3

[0066] An adsorbent antibacterial filter paper for food; prepared from the following raw materials in parts by weight: 80 parts of softwood fiber, 30 parts of nano-silica, 10 parts of chitosan, 1 part of polyamide polyamine epichlorohydrin, 2 parts of xanthan gum, 0.06 part of polydimethylsiloxane.

[0067] The adsorbent antibacterial filter paper for food is prepared through the following steps:

[0068] S1: Cook the softwood fiber raw material at 160 - 170 °C for 2 h by the sulfate method, and beat the pulp with the assistance of ultrasonic waves to make a uniform pulp slurry with a concentration of 3% - 6%;

[0069] S2: Dissolve chitosan with a deacetylation degree of 90% in 1% - 3% dilute acetic acid to make a chitosan solution;

[0070] S3: Mix the chitosan solution with the pulp slurry, and add 30 parts by weight of nano-silica, 1 part by weight of polyamide polyamine epichlorohydrin, 2 parts by weight of xanthan gum, and 0.06 part by weight of polydimethylsiloxane and stir evenly;

[0071] S4: Dilute the pulp to a concentration of 0.1% - 1.5% to form a uniform suspension, and distribute the pulp onto the forming wire through a headbox to form a wet paper web;

[0072] S5: The wet paper web passes through a press roll, and the pressing pressure is adjusted within the range of 0.1 - 1 MPa according to the paper type for further dehydration and compaction; then it passes through a steam-heated drying cylinder to remove the remaining moisture at 100 - 150 °C to dry the paper. Then, the smoothness and gloss of the paper are improved through a calender roll. Finally, the filter paper is placed in a hot press and treated under the conditions of 100 - 200 °C and 0.5 - 1 MPa for 1 - 2 h.

[0073] Example 4

[0074] The difference between this example and Example 1 is only that the weight fraction of chitosan added in step S2 of Example 4 is 1.5 parts.

[0075] Example 5

[0076] The difference between this example and Example 1 is only that the chitosan added in step S2 of Example 5 has a deacetylation degree of 40%.

[0077] Example 6

[0078] The difference between this example and Example 1 is only that no chitosan is added in Example 6.

[0079] Example 7

[0080] Example 7 is only different from Example 1 in that Example 7 adds conventional inorganic fillers such as calcium carbonate and silica.

[0081] Comparative Example 1

[0082] This comparative example is a filter paper manufactured by a conventional wet process.

[0083] The antibacterial properties and adsorption properties of Examples 1-6 and Comparative Example 1 were tested. The specific test methods are as follows:

[0084] Antibacterial property test:

[0085] The antibacterial property of the filter paper was tested using the contact method: (1) Cut the filter paper sample into small square pieces with a length and width of 0.5 cm each, and place them in a sterile petri dish; (2) Add 10 mL of Escherichia coli suspension with a concentration of 100 CFU / mL, and completely immerse the shredded filter paper pieces in the petri dish; (3) Incubate at 37 °C for 24 h; (4) Take out the shredded filter paper pieces, rinse them with sterile normal saline, and collect the rinsing solution; (5) Dilute the rinsing solution 10 times, spread it on an agar plate, and count the number of colonies after culturing for 48 h; (6) Calculate the bacterial reduction rate; (7) Repeat the experiment 3 times under the same conditions, and take the average value as the result.

[0086] Adsorption property test:

[0087] The adsorption property of the filter paper was tested using the dynamic contact method: (1) Install the filter paper sample in the filtration device; (2) Slowly add 1 L of sunset yellow solution with a concentration of 0.1 g / L to the container; (3) Collect the filtrate and measure the concentration of the sunset yellow solution in the filtrate; (4) Calculate the adsorption capacity; (5) Repeat the experiment 3 times under the same conditions, and take the average value as the result.

[0088] Replace the 0.1 g / L sunset yellow solution in step (2) with a 10 mg / L copper chloride solution, and conduct the adsorption property test again to test the adsorption effect of the filter paper on heavy metal ions.

[0089] Mechanical strength test: (1) Tensile strength test: (2) Cut the filter paper sample into small pieces with a length and width of 1 cm each; (3) Clamp the filter paper sample in the fixture of the tensile testing machine; (4) Stretch the sample at a constant rate until it breaks; (5) Record the maximum tensile force and the elongation at break.

[0090] Tensile strength test: (1) Cut the filter paper sample into small pieces with a length and width of 1 cm each; (2) Clamp the filter paper sample in the fixture of the tensile strength testing machine; (3) Apply a uniformly increasing pressure until the filter paper sample ruptures; (4) Record the pressure when the filter paper sample ruptures; (5) Calculate the tensile strength of the filter paper sample.

[0091] Wet strength test: (1) Cut the filter paper sample into small pieces with a length and width of 1 cm each; (2) Immerse the sample completely in water and keep it immersed for 5 min; (3) Clamp the filter paper sample in the fixture of the tensile testing machine; (4) Stretch the sample at a constant rate until it breaks; (5) Record the maximum tensile force and the elongation at break.

[0092] Chemical safety test:

[0093] Migration test:

[0094] Use edible oil as the simulation liquid, contact the filter paper and the edible oil at room temperature for 7 days, and use liquid chromatography technology to analyze the migrated chemical substances.

[0095] Residual solvent detection:

[0096] Cut the filter paper sample into pieces and put them into a headspace vial. Use a headspace sampler to heat the filter paper sample to volatilize the residual solvent in the filter paper, and finally analyze the volatile organic compounds in it by gas chromatography technology.

[0097] Heavy metal detection:

[0098] Use acid to digest the filter paper sample to convert heavy metals into detectable ionic forms, and use atomic absorption spectrometry to analyze the heavy metal ion components in the solution.

[0099] Formaldehyde detection:

[0100] The formaldehyde content in the filter paper sample was determined by acetylacetone spectrophotometry. The filter paper sample was cut into pieces, 1 g of filter paper fragments were taken, added with 50 mL of distilled water and soaked for 24 h, filtered, 5 mL of the filtrate was taken and added with 5 mL of acetylacetone, and heated in a water bath at 60 °C for 30 min. The absorbance was measured with a spectrophotometer at a wavelength of 412 nm. Formaldehyde standard solutions with concentrations of 0, 1, 2, 5, and 10 mg / L were respectively prepared, the absorbances were measured, and a standard curve was plotted. The concentration of formaldehyde in the filtrate was calculated according to the standard curve.

[0101] The test results of antibacterial performance and adsorption performance are shown in Table 1

[0102] Table 1 Bacterial reduction rate Pigment adsorption rate Heavy metal ion adsorption rate Example 1 99％ 98％ 98％ Example 2 97％ 95％ 94％ Example 3 99％ 98％ 98％ Example 4 75％ 74％ 78％ Example 5 53％ 51％ 47％ Example 6 15％ 43％ 47％ Example 7 15％ 58％ 51％ Comparative Example 1 15％ 25％ 19％

[0103] In order to fit the actual situation of food production, the above experiments used representative Escherichia coli suspensions, low-concentration artificial pigment (sunset yellow) solutions, and low-concentration heavy metal (copper chloride) solutions.

[0104] The antibacterial effect of chitosan is mainly affected by factors such as chitosan concentration, degree of deacetylation, environmental conditions, and contact mode.

[0405] Comparing the data of Examples 1-4, it can be obtained that the chitosan concentration in Example 1 is 7.3 wt%, the chitosan concentration in Example 2 is 6.1 wt%, the chitosan concentration in Example 3 is 8.1 wt%, and the chitosan concentration in Example 4 is 1.5 wt%. It is easy to conclude that when other conditions such as the degree of deacetylation and temperature are the same, the antibacterial effect of higher-concentration chitosan is better.

[0106] Comparing the data of Example 1 and Example 5, it can be obtained that the antibacterial effect of the filter paper containing chitosan with a high degree of deacetylation is significantly stronger than that of the filter paper containing chitosan with a low degree of deacetylation. This is because the reactivity of chitosan is related to the content of free amino groups on the chitosan molecule. Chitosan with a high degree of deacetylation (>85%) has strong reactivity, and at this time the content of free amino groups on the chitosan molecule is high. Because free amino groups can destroy the cell membrane of bacteria, when other conditions are the same, chitosan with a high degree of deacetylation shows strong antibacterial properties.

[0107] Comparing the data of Example 1 and Example 6, it can be obtained that chitosan has a great influence on the antibacterial performance and adsorption performance of filter paper. This is because other components of the filter paper do not have antibacterial effects, and the antibacterial performance of the filter paper is mainly manifested in the content of free amino groups of chitosan. Since chitosan molecules contain a large number of amino and hydroxyl groups, they can adsorb substances through various ways such as hydrogen bonding, electrostatic interaction, and chelation, and have strong adsorption ability. In Example 1, chitosan and inorganic fillers including adsorbents such as activated carbon, nano-silica, and nano-silicon oxide act together to better remove artificial pigments and heavy metal ions in food.

[0108] Comparing the data of Comparative Example 1 and Example 7, it can be obtained that: the adsorption rates of Example 7 for pigments and heavy metal ions are significantly reduced. This is because conventional fillers including calcium carbonate, silica, etc. do not have an adsorption effect, and relying solely on the adsorption effect of chitosan is not sufficient to remove pigments and heavy metal ions in food well.

[0109] Comparing the data of Comparative Example 1 and Comparative Example 1, it can be obtained that: the adsorptive antibacterial filter paper of the present invention is significantly stronger than ordinary filter paper in terms of antibacterial performance and adsorption performance.

[0110] The test results of mechanical strength and wet strength are shown in Table 2

[0111] Table 2 Elongation at break Tensile strength Elongation at break (wet state) Example 1 11.3％ <![CDATA[≥9KN / cm 2 > 7.6％ Example 2 10.5％ <![CDATA[≥9KN / cm 2 > 7.3％ Example 3 10.7％ <![CDATA[≥9KN / cm 2 > 7.4％ Comparative Example 1 10％ <![CDATA[≥5KN / cm 2 > 4％

[0112] Combined with the data in Table 2, it can be obtained that the mechanical strength and wet strength of the adsorptive antibacterial filter paper for food of the present invention are higher than those of ordinary filter paper, and it can meet the needs of the food production process. Since food filter paper is mostly used for liquid foods, the filter paper of the present invention has a high wet strength and can better meet the needs of actual production.

[0113] The raw materials used in the present invention mainly include: softwood fibers, nano-silica, chitosan, polyamide polyamine epichlorohydrin, xanthan gum, polydimethylsiloxane, etc., and none of them contain toxic substances. Softwood fibers belong to natural fibers, are harmless to the human body and can be naturally degraded.

[0114] Softwood fibers belong to natural fibers, are harmless to the human body and can be naturally degraded.

[0115] Nano-silica can improve the filtration accuracy, adsorption capacity and mechanical strength of the filter paper, has stable chemical properties, is non-toxic to the human body, and after the filter paper itself degrades, these inorganic fillers have no pollution to the environment.

[0116] Chitosan is a natural polysaccharide, which will decompose above 280°C, and the decomposition products are harmless to the human body. Chitosan has broad-spectrum antibacterial properties and can effectively inhibit the growth of bacteria, fungi and molds. During the preparation of the filter paper, chitosan and filter paper fibers are mixed to make chitosan evenly dispersed in the slurry, which can make the modification effect of chitosan stable. Through subsequent drying and curing steps, chitosan is stably combined with the filter paper. And chitosan can form a large number of hydrogen bonds with cellulose fibers to improve the strength and durability of the filter paper. The porous structure and adsorption performance of chitosan itself can enhance the filtration efficiency and adsorption capacity of the filter paper. Combined with the adsorbent in the inorganic filler, it can improve the adsorption effect of the filter paper. Chitosan also has characteristics such as degradability and good biocompatibility, meeting the requirements of environmental protection.

[0117] Polyamide polyamine epichlorohydrin has good stability at room temperature, does not contain harmful substances such as formaldehyde, belongs to an environmentally friendly wet strength agent, and has good compatibility with other papermaking chemicals without affecting other properties of the paper. When in use, PAE can be directly added to the pulp without other treatment processes, which is convenient to use.

[0118] Xanthan gum is a polysaccharide substance produced by microbial fermentation, has high viscosity and good stability, and has no toxic effect on the human body.

[0119] Since chitosan and nano-silica are directly mixed with the pulp during the manufacturing process of the filter paper and the filter paper is made after subsequent treatment, chitosan and nano-silica are stably combined with the filter paper fibers, and are not likely to migrate during normal use and do not produce other harmful chemical substances.

[0120] The raw materials and additives used in the manufacturing process of the filter paper do not contain heavy metals, and no heavy metal ions are detected during the above heavy metal ion detection process.

[0121] For the filter paper samples of Examples 1-4 and Comparative Example 1, formaldehyde was not detected in the filtrate by the acetylacetone spectrophotometry, which proves that the filter paper does not contain formaldehyde and has high safety.

[0122] The raw materials and equipment used in the present invention, unless otherwise specified, are common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0123] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes and equivalent transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An adsorbent antibacterial filter paper for food, characterized in that: The adsorbent antibacterial filter paper for food is prepared from the following raw materials in parts by weight: 60-80 parts of pulp fiber, 15-30 parts of porous inorganic filler, 5-10 parts of chitosan and 1-2 parts of papermaking additive.

2. The adsorbent antibacterial filter paper for food according to claim 1, characterized in that: The pulp fiber is selected from one or more of coniferous wood pulp fiber, sulfite wood pulp fiber, and cotton pulp fiber.

3. The adsorbent antibacterial filter paper for food according to claim 1 or 2, characterized in that: The porous inorganic filler is selected from one or more of activated carbon, nano-silicon dioxide, diatomaceous earth and bentonite.

4. The adsorbent antibacterial filter paper for plant-based food according to any one of claims 1 to 3, characterized in that: The deacetylation degree of the chitosan is 75%-95%.

5. The adsorbent antibacterial filter paper for food according to any one of claims 1 to 4, characterized in that: The papermaking additives are: 0.5-1 part of wet strength agent, 1-2 parts of natural thickener, and 0.03-0.06 parts of defoaming agent.

6. The adsorbent antibacterial filter paper for food according to claim 5, characterized in that: The wet strength agent is polyamide polyamine epichlorohydrin PAE.

7. The adsorbent antibacterial filter paper for food according to claim 5, characterized in that: The natural thickener is selected from one or more of gelatin, pectin and starch.

8. The adsorbent antibacterial filter paper for food according to claim 5, characterized in that: The defoaming agent is selected from one or more of polydimethylsiloxane, modified silicone, a mixture of food-grade mineral oil and emulsifier, and food-grade fatty acid ester.

9. A method for preparing the adsorptive antibacterial filter paper for food according to any one of claims 1 to 7, comprising the following steps: S1: Cooking and beating the fiber raw materials to prepare uniform pulp slurry; S2: dissolving chitosan in dilute acid to prepare a chitosan solution; S3: mixing the chitosan solution with the pulp slurry, adding the inorganic filler, wet strength agent, natural thickener and defoamer and stirring evenly; S4: diluting the pulp and distributing the pulp onto the forming wire through a headbox to form a wet paper web; S5: The wet paper web is made into finished product through dehydration, compaction, drying and hot pressing processes.

10. The method for preparing the adsorptive antibacterial filter paper for food according to claim 9, characterized in that: The dilute acid is selected from one or more of acetic acid, citric acid and acetic acid.