Method for extracting cellulose from soy sauce residue for the preparation of food packaging films

Abstract

The present application relates to the field of packaging materials, and discloses a method for extracting cellulose from soy sauce residues for preparing food packaging film. The preparation process uses soy sauce residues as raw materials, and after the processes of desalting, drying, degreasing, decoloring, alkalization, acetylation modification, plasticization modification and film preparation, an excellent food packaging material is prepared. The food packaging film prepared by the method retains the environmental protection advantages of biodegradability of natural cellulose and has high safety. Meanwhile, through modification, the aggregation structure of cellulose itself is greatly improved, and glyceryl tri(ethylhexanoate) further reduces the hydrogen bond interaction between cellulose molecules, so that an excellent food packaging film material with smooth and transparent appearance, strong compression plasticity and high tensile strength is prepared.

Description

Technical Field

[0001] This invention relates to the field of packaging materials, and more specifically discloses a method for extracting cellulose from soy sauce residue for preparing food packaging films. Background Technology

[0002] Soy sauce is a traditional Chinese condiment, rich in nutrients and with a delicious flavor, making it an indispensable ingredient in Chinese family kitchens and restaurants. China consumes over 4 million tons of soy sauce annually, using over 500,000 tons of whole soybeans for brewing. Soy sauce residue, the waste generated after soy sauce production, is highly perishable due to its high moisture content and rich nutrients, making it difficult to preserve. Furthermore, the sheer volume of soy sauce residue means that direct disposal would result in significant resource waste and environmental pollution. Therefore, its treatment and utilization have become one of the urgent problems that the soy sauce industry needs to solve.

[0003] There are three main directions for utilizing soy sauce residue: First, to retain the nutrients in the residue directly or after processing and use it as feed for animal husbandry or as a microbial culture medium; second, to extract high-value-added components such as isoflavones, oils, proteins, and pigments from the residue; and third, some new applications that have developed in recent years, such as the preparation of bioadsorbents, composite binders, and other biomaterials.

[0004] Currently, there are numerous reports on the reuse of soy sauce residue, focusing primarily on the recovery and reuse of oils, isoflavones, and pigments. The reuse of the abundant fiber contained within the residue receives little attention. If, in addition to the traditional recovery and reuse of oils, isoflavones, and pigments from soy sauce residue, the rich cellulose content were further utilized, the utilization rate of the residue could be significantly increased, expanding economic benefits. Furthermore, with increasingly stringent environmental regulations, the environmental pollution caused by packaging materials derived from petrochemical products is becoming increasingly serious. Biodegradable packaging materials have broad development prospects in the future, and given the biodegradable nature of cellulose, its application in packaging materials is clearly more in line with environmental requirements. However, due to the excessively strong intermolecular hydrogen bonding network of cellulose, its poor thermoforming properties, high hydroxyl density in the molecular chain, strong hydrophilicity, and weak mechanical properties, cellulose is difficult to directly apply in daily life and production. Summary of the Invention

[0005] This invention provides a method for extracting cellulose from soy sauce residue for preparing food packaging films, in order to solve the problems of insufficient utilization of soy sauce residue and difficulty in directly applying cellulose to daily life and production in the existing technology.

[0006] To solve the above-mentioned technical problems, according to one aspect of the present invention, more specifically, a method for extracting cellulose from soy sauce residue for preparing food packaging film, comprising the following steps:

[0007] S1. Desalting: Mix soy sauce residue and water thoroughly at a weight ratio of 1:3-10 for 1-3 hours, filter to remove water, and repeat this operation 2-3 times to obtain desalted wet residue 1.

[0008] S2. Drying: The wet residue 1 prepared in step S1 is dried by blowing at 50-80℃ to obtain dry residue 2.

[0009] S3, Degreasing: The dry residue 2 prepared in step S2 and methyl tert-butyl ether are thoroughly mixed in a reaction vessel at a weight ratio of 1:2-8. The mixture is heated and stirred for 1-2 hours. The methyl tert-butyl ether is removed by hot filtration. The remaining residue is transferred back into the reaction vessel, and 80% ethanol solution is added. The mixture is heated and stirred for 1-2 hours. The ethanol solution is removed by hot filtration to obtain residue 3. The mass ratio of 80% ethanol solution to dry residue 2 is 1:2-9.

[0010] S4. Decolorization: The residue 3 prepared in step S3, sodium hypochlorite solution, and water are stirred thoroughly for 0.5-1 h at a weight ratio of 1:3:5-9. After the reaction is completed, the solution is filtered out to obtain residue 4.

[0011] S5. Alkalization: The residue 4 prepared in step S4 and the sodium hydroxide solution are thoroughly mixed at a weight ratio of 1:5-10. The mixture is heated to 85℃ and stirred for 1-2 hours. The solution is removed by hot filtration. The residue is washed with water until neutral and dried with a forced air to constant weight. After being crushed by a pulverizer, residue 5 is obtained.

[0012] S6. Acetylation Modification: The residue 5 prepared in step S5, glacial acetic acid, and acetic anhydride are mixed in a weight ratio of 1:3:3 and cooled to 0-5℃. Then, concentrated sulfuric acid with a weight ratio of 0.1 times that of residue 5 is added, and the temperature is controlled at 20-38℃ for 3-5 hours. Sodium acetate aqueous solution with a weight ratio of 1-2 times that of residue 5 is added to the reaction system, and the mixture is stirred at 20-25℃ for 1-2 hours. After the reaction is completed, the mixture is filtered, and the filtrate is added to a dilute acetic acid solution for sedimentation for 1-3 hours. The sedimented material is granulated by a granulator, filtered to remove the solvent, and the solid is dried to obtain cellulose acetate.

[0013] S7. Plasticizing modification: The cellulose acetate and triglyceride triethylhexanoate prepared in step S6 are added to a twin-screw extruder at a weight ratio of 100:10-25. After extrusion through a dual-die, the mixture is cooled in a water bath and granulated to obtain modified cellulose granules.

[0014] S8. Film Forming: Add the modified cellulose particles prepared in step S7 to an injection molding machine and injection mold them into food packaging film material of the desired shape.

[0015] Furthermore, in step S1, the sodium chloride content of wet residue 1 is 1.6-6.0%.

[0016] Furthermore, in step S2, the drying loss of dry residue 2 does not exceed 5.0%.

[0017] Furthermore, in step S3, the extraction temperature is 55-64℃.

[0018] Furthermore, in step S4, the effective chlorine content of the sodium hypochlorite solution is 6-14%.

[0019] Furthermore, in step S5, the concentration of the sodium hydroxide solution is 8-15%, and the drying loss of residue 5 does not exceed 2.0%.

[0020] Furthermore, in step S6, the concentration of the dilute acetic acid solution is 5-12%.

[0021] Furthermore, in step S7, the extruder inlet temperature is set to 90-110℃, the die zone temperature to 150-220℃, and the screw speed to 240-300 rpm.

[0022] Beneficial Effects: The method for extracting cellulose from soy sauce residue for preparing food packaging film disclosed in this invention can extract and utilize a large amount of natural fiber material from soy sauce residue, filling the gap in the recycling of cellulose from soy sauce residue, greatly improving the value of soy sauce residue recycling, increasing benefits, and reducing the environmental pollution caused by soy sauce residue. Furthermore, the food packaging film prepared by this method retains the environmentally friendly advantages of natural cellulose's biodegradability and has high safety. Simultaneously, through modification, the aggregated structure of cellulose itself is greatly improved, and triglyceride (ethylhexanoate) further reduces the hydrogen bonding between cellulose molecules, resulting in a high-performance food packaging film material with a smooth and transparent appearance, strong compressibility, and high tensile strength. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0024] Figure 1 This is a schematic diagram of the preparation process.

[0025] Figure 2 The image shows an SEM image of packaging material 1 prepared in Example 1.

[0026] Figure 3 The image shows a SEM image of packaging material 2 prepared in Example 2.

[0027] Figure 4 The image shows a SEM image of packaging material 3 prepared in Example 3. Detailed Implementation

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0029] Example 1

[0030] 120 kg of soy sauce residue and 360 kg of water were added to a mixing vessel and stirred for 3 hours. The mixture was then filtered by centrifuge. The residue was added back to 360 kg of water and stirred for 3 hours. The mixture was then centrifuged and filtered again. The residue was added back to 360 kg of water and stirred for 3 hours. The mixture was then centrifuged and filtered again. The salt content of the sample was found to be 1.6%. The residue was dried at 50°C for 8 hours with forced air drying, and the loss on drying was 4.1%.

[0031] Add 100 kg of the dried filter residue and 200 kg of methyl tert-butyl ether to the reactor, heat to 55°C, stir for 2 hours, filter while hot, transfer the filter residue to the reactor, add 200 kg of 80% ethanol solution, heat to 64°C, stir for 2 hours, filter while hot to remove ethanol, and weigh 80 kg after removing the solvent.

[0032] The residue after ethanol extraction was added to a reaction vessel, followed by 400 kg of water and 240 kg of sodium hypochlorite solution with an effective chlorine content of 14%. The mixture was stirred for 0.5 h, centrifuged, filtered, and the solution was removed.

[0033] The alkalized residue was added to a reaction vessel, and after removing the solvent, the weight was 80 kg. 400 kg of 15% sodium hydroxide solution was added, and the mixture was heated to 85°C and stirred for 2 hours. The solution was removed by hot filtration, and the filter residue was washed with water until neutral. It was then dried at 60°C with forced air until the weight loss was 2.0%. The residue was then added to a pulverizer and pulverized for 10 minutes. 50 kg of fiber residue was collected.

[0034] Add 50 kg of the above-mentioned fiber residue, 150 kg of glacial acetic acid, and 150 kg of acetic anhydride to a reaction vessel, start stirring, cool to 0°C, then slowly add 5 kg of concentrated sulfuric acid, maintaining the temperature at 20-38°C, and react for 3 hours. Add 50 kg of 18% sodium acetate aqueous solution to the reaction system, and stir at 20-25°C for 2 hours. Filter, transfer the filtrate to a reaction vessel, add 200 kg of 5% acetic acid solution, allow to settle for 1 hour, granulate the settled liquid using a granulator, centrifuge and filter to remove the solvent, and dry at 70°C for 10 hours to obtain cellulose acetate.

[0035] 30 kg of cellulose acetate and 3 kg of triglyceride (ethylhexanoate) were added sequentially to a twin-screw extruder. The feed inlet temperature was 90°C. After feeding, the feed inlet was held for 30 minutes. The die temperature was gradually increased from 150 to 220°C. The screw speed was 240 rpm. The extrusion was carried out through a dual-die, cooled in a 15°C water bath, and then cut and granulated.

[0036] The modified fiber particles were fed into the injection molding machine through the feed port. The temperature in the feed zone was 200°C. The temperature from the feed zone to the nozzle zone increased from 200°C to 220°C. The holding pressure was 1000 bar. After entering the mold for shaping and cooling, packaging material 1 was obtained.

[0037] Example 2

[0038] 120 kg of soy sauce residue and 1200 kg of water were added to a mixing vessel and stirred for 1 hour. The mixture was then filtered by centrifuge. The residue was added back to 1200 kg of water and stirred for 1 hour. The mixture was then centrifuged and filtered again. The salt content of the sample was found to be 6.0%. The residue was dried at 50°C for 8 hours, and the loss on drying was 5.0%.

[0039] Add 100 kg of the dried filter residue and 800 kg of methyl tert-butyl ether to the reactor, heat to 55°C, stir for 1 hour, filter while hot, transfer the filter residue to the reactor, add 900 kg of 80% ethanol solution, heat to 55°C, stir for 1 hour, filter while hot to remove ethanol, and weigh 76 kg after removing the solvent.

[0040] The residue after ethanol extraction was added to a reaction vessel, followed by 684 kg of water and 228 kg of sodium hypochlorite solution with an effective chlorine content of 6%. The mixture was stirred for 1 hour, centrifuged, filtered, and the solution was removed.

[0041] The alkalized residue was added to the reaction vessel, and after removing the solvent, the weight was 75 kg. 750 kg of 8% sodium hydroxide solution was added, and the mixture was heated to 85°C and stirred for 1 hour. The solution was removed by hot filtration, and the filter residue was washed with water until neutral. It was dried at 60°C with forced air until the weight loss was 1.8%. Then it was added to a pulverizer and pulverized for 10 minutes. 48 kg of fiber residue was collected.

[0042] Add 48 kg of the above-mentioned fiber residue, 144 kg of glacial acetic acid, and 144 kg of acetic anhydride to a reaction vessel, start stirring, cool to 5°C, then slowly add 4.8 kg of concentrated sulfuric acid, maintaining the temperature at 20-38°C, and react for 5 hours. Add 96 kg of 6% sodium acetate aqueous solution to the reaction system, and stir at 20-25°C for 2 hours. Filter, transfer the filtrate to a reaction vessel, add 200 kg of 12% acetic acid solution, allow to settle for 3 hours, granulate the settled liquid using a granulator, centrifuge and filter to remove the solvent, and dry at 70°C for 10 hours to obtain cellulose acetate.

[0043] 30 kg of cellulose acetate and 6 kg of triglyceride (ethylhexanoate) were added sequentially to a twin-screw extruder. The feed inlet temperature was 110°C. After feeding, the feed inlet was held for 30 minutes. The die temperature was gradually increased from 150 to 220°C. The screw speed was 300 rpm. The extrusion was carried out through a dual-die, cooled in a 10°C water bath, and then cut and granulated.

[0044] The modified fiber particles were fed into the injection molding machine through the feed port. The temperature in the feed zone was 200°C. The temperature from the feed zone to the nozzle zone increased from 200°C to 220°C. The holding pressure was 1000 bar. After entering the mold for shaping and cooling, packaging material 2 was obtained.

[0045] Example 3

[0046] 120 kg of soy sauce residue and 1200 kg of water were added to a mixing vessel and stirred for 1 hour. The mixture was then filtered by centrifuge. The residue was added back to 1200 kg of water and stirred for 1 hour. The mixture was then centrifuged and filtered again. The salt content of the sample was found to be 4.1%. The residue was dried at 50°C for 8 hours, and the loss on drying was 5.0%.

[0047] Add 100 kg of the dried filter residue and 800 kg of methyl tert-butyl ether to the reactor, heat to 55°C, stir for 1 hour, filter while hot, transfer the filter residue to the reactor, add 900 kg of 80% ethanol solution, heat to 55°C, stir for 1 hour, filter while hot to remove ethanol, and weigh 76 kg after removing the solvent.

[0048] The residue after ethanol extraction was added to a reaction vessel, followed by 684 kg of water and 228 kg of sodium hypochlorite solution with an effective chlorine content of 6%. The mixture was stirred for 1 hour, centrifuged, filtered, and the solution was removed.

[0049] The alkalized residue was added to the reaction vessel, and after removing the solvent, the weight was 75 kg. 750 kg of 8% sodium hydroxide solution was added, and the mixture was heated to 85°C and stirred for 1 hour. The solution was removed by hot filtration, and the filter residue was washed with water until neutral. It was dried at 60°C with forced air until the weight loss was 1.8%. Then it was added to a pulverizer and pulverized for 10 minutes. 48 kg of fiber residue was collected.

[0050] Add 48 kg of the above-mentioned fiber residue, 144 kg of glacial acetic acid, and 144 kg of acetic anhydride to a reaction vessel, start stirring, cool to 5°C, then slowly add 4.8 kg of concentrated sulfuric acid, maintaining the temperature at 20-38°C, and react for 5 hours. Add 96 kg of 6% sodium acetate aqueous solution to the reaction system, and stir at 20-25°C for 2 hours. Filter, transfer the filtrate to a reaction vessel, add 200 kg of 12% acetic acid solution, allow to settle for 3 hours, granulate the settled liquid using a granulator, centrifuge and filter to remove the solvent, and dry at 70°C for 10 hours to obtain cellulose acetate.

[0051] 30 kg of cellulose acetate and 7.5 kg of triglyceride (ethylhexanoate) were added sequentially to a twin-screw extruder. The feed inlet temperature was 110℃. After feeding, the feed inlet was held for 30 minutes. The die temperature was gradually increased from 150 to 220℃. The screw speed was 300 rpm. The extrusion was carried out through a dual-die, cooled in a 10℃ water bath, and then cut and granulated.

[0052] The modified fiber particles were fed into the injection molding machine through the feed port. The temperature in the feed zone was 200°C. The temperature from the feed zone to the nozzle zone increased from 200°C to 220°C. The holding pressure was 1000 bar. After entering the mold for shaping and cooling, packaging material 3 was obtained.

[0053] Comparative Example 1

[0054] 120 kg of soy sauce residue and 1200 kg of water were added to a mixing vessel and stirred for 1 hour. The mixture was then filtered by centrifuge. The residue was added back to 1200 kg of water and stirred for 1 hour. The mixture was then centrifuged and filtered again. The salt content of the sample was found to be 6%. The residue was dried at 50°C for 8 hours, and the loss on drying was 5.0%.

[0055] Add 100 kg of the dried filter residue and 800 kg of methyl tert-butyl ether to the reactor, heat to 55°C, stir for 1 hour, filter while hot, transfer the filter residue to the reactor, add 900 kg of 80% ethanol solution, heat to 55°C, stir for 1 hour, filter while hot to remove ethanol, and weigh 76 kg after removing the solvent.

[0056] The residue after ethanol extraction was added to a reaction vessel, followed by 684 kg of water and 228 kg of sodium hypochlorite solution with an effective chlorine content of 6%. The mixture was stirred for 1 hour, centrifuged, filtered, and the solution was removed.

[0057] The alkalized residue was added to the reaction vessel, and after removing the solvent, the weight was 75 kg. 750 kg of 8% sodium hydroxide solution was added, and the mixture was heated to 85°C and stirred for 1 hour. The solution was removed by hot filtration, and the filter residue was washed with water until neutral. It was dried at 60°C with forced air until the weight loss was 1.8%. Then it was added to a pulverizer and pulverized for 10 minutes. 48 kg of fiber residue was collected.

[0058] Add 48 kg of the above-mentioned fiber residue, 144 kg of glacial acetic acid, and 144 kg of acetic anhydride to a reaction vessel, start stirring, cool to 5°C, then slowly add 4.8 kg of concentrated sulfuric acid, maintaining the temperature at 20-38°C, and react for 5 hours. Add 96 kg of 6% sodium acetate aqueous solution to the reaction system, and stir at 20-25°C for 2 hours. Filter, transfer the filtrate to a reaction vessel, add 200 kg of 12% acetic acid solution, allow to settle for 3 hours, granulate the settled liquid using a granulator, centrifuge and filter to remove the solvent, and dry at 70°C for 10 hours to obtain cellulose acetate.

[0059] The modified fiber particles were fed into the injection molding machine through the feed port. The temperature in the feed zone was 200°C. The temperature from the feed zone to the nozzle zone rose from 200°C to 220°C. The holding pressure was 1000 bar. After entering the mold for shaping and cooling, packaging material 4 was obtained.

[0060] Test example:

[0061] Morphological characterization: The microstructure of the prepared injection-molded thin film materials was observed using scanning electron microscopy. The samples were deposited on an aluminum stage, and a thin gold conductive layer was sputtered onto them. The film surface was observed using a secondary electron detector at an accelerating voltage of 20 kV. SEM images of materials 1, 2, and 3 are shown below. Figure 2 , 3 4. As the amount of plasticizer triglyceride (ethylhexanoate) added increases, the surface smoothness decreases.

[0062] Tensile strength: The tensile strength of the test specimen was tested according to GB / T 1040.2—2006. Specimen shape: Type 1A; dimensions: 25mm × 5mm × 1mm; loading rate: 5mm / min; preparation method: injection molding; five tests were performed and the average value was taken. The test conditions were 25℃ and 50% relative humidity. The test results are shown in Table 1.

[0063] Table 1 Summary of Packaging Material Test Results

[0064]

[0065] Note: The amount of plasticizer added is relative to the weight of cellulose acetate.

[0066] The results above show that increasing the amount of plasticizer triglyceride (ethylhexanoate) decreases light transmittance; the tensile strength reaches its maximum at a 20% addition level, which is 2.1 times that of the sample without added triglyceride (ethylhexanoate). These results indicate that modified cellulose significantly improves its aggregated structure, and triglyceride (ethylhexanoate) further reduces the hydrogen bonding between cellulose molecules. This method can prepare high-performance packaging materials using soy sauce residue as material, possessing the biodegradable characteristics of fiber packaging materials. Furthermore, after modification, the materials are smooth and transparent, exhibiting strong compressibility and high tensile strength.

[0067] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention are also within the protection scope of the present invention.

Claims

1. A method for extracting cellulose from soy sauce residue for preparing food packaging films, characterized in that, Includes the following steps: S1. Desalting: Mix soy sauce residue and water thoroughly at a weight ratio of 1:3-10 for 1-3 hours, filter to remove water, and repeat this operation 2-3 times to obtain desalted wet residue 1. S2. Drying: The wet residue 1 prepared in step S1 is dried by blowing at 50-80℃ to obtain dry residue 2. S3, Degreasing: The dry residue 2 prepared in step S2 and methyl tert-butyl ether are thoroughly mixed in a reaction vessel at a weight ratio of 1:2-8. The mixture is heated and stirred for 1-2 hours. The methyl tert-butyl ether is removed by hot filtration. The remaining residue is transferred back into the reaction vessel, and 80% ethanol solution is added. The mixture is heated and stirred for 1-2 hours. The ethanol solution is removed by hot filtration to obtain residue 3. The mass ratio of 80% ethanol solution to dry residue 2 is 1:2-9. S4. Decolorization: The residue 3 prepared in step S3, sodium hypochlorite solution, and water are stirred thoroughly for 0.5-1 h at a weight ratio of 1:3:5-9. After the reaction is completed, the solution is filtered out to obtain residue 4. S5. Alkalization: The residue 4 prepared in step S4 and the sodium hydroxide solution are thoroughly mixed at a weight ratio of 1:5-10. The mixture is heated to 85℃ and stirred for 1-2 hours. The solution is removed by hot filtration. The residue is washed with water until neutral and dried with a forced air to constant weight. After being crushed by a pulverizer, residue 5 is obtained. S6. Acetylation Modification: The residue 5 prepared in step S5, glacial acetic acid, and acetic anhydride are mixed in a weight ratio of 1:3:3 and cooled to 0-5℃. Then, concentrated sulfuric acid with a weight ratio of 0.1 times that of residue 5 is added, and the temperature is controlled at 20-38℃ for 3-5 hours. Sodium acetate aqueous solution with a weight ratio of 1-2 times that of residue 5 is added to the reaction system, and the mixture is stirred at 20-25℃ for 1-2 hours. After the reaction is completed, the mixture is filtered, and the filtrate is added to a dilute acetic acid solution for sedimentation for 1-3 hours. The sedimented material is granulated by a granulator, filtered to remove the solvent, and the solid is dried to obtain cellulose acetate. S7. Plasticizing modification: The cellulose acetate and triglyceride triethylhexanoate prepared in step S6 are added to a twin-screw extruder at a weight ratio of 100:10-25. After extrusion through a dual-die, the mixture is cooled in a water bath and granulated to obtain modified cellulose granules. S8. Film Forming: Add the modified cellulose particles prepared in step S7 to an injection molding machine and injection mold them into food packaging film material of the desired shape.

2. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S1, the sodium chloride content of wet residue 1 is 1.6-6.0%.

3. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S2, the drying loss of the dry residue 2 does not exceed 5.0%.

4. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S3, the extraction temperature is 55-64℃.

5. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S4, the effective chlorine content of the sodium hypochlorite solution is 6-14%.

6. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S5, the concentration of sodium hydroxide solution is 8-15%, and the weight loss of residue 5 upon drying does not exceed 2.0%.

7. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S6, the concentration of the dilute acetic acid solution is 5-12%.

8. The method for extracting cellulose from soy sauce residue for preparing food packaging film according to claim 1, characterized in that: In step S7, the extruder inlet temperature is set to 90-110℃, the die zone temperature to 150-220℃, and the screw speed to 240-300 rpm.

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