Method for producing regenerated cellulose fiber using modified milk protein

Abstract

This invention provides a method for producing modified milk protein-regenerated cellulose fibers that improves the stability of milk proteins and enhances the binding properties between milk proteins and fibers. [Solution] The present invention involves condensing the N-terminus and C-terminus of a whey protein peptide to form a cyclic milk protein having an amide ring structure, and further esterifying some of its hydroxyl groups with acryloyl chloride to obtain a modified cyclic milk protein having acrylate groups. This modified protein is grafted onto cellulose to produce regenerated cellulose fibers. According to the present invention, the chemical stability of the protein and its binding affinity to cellulose are improved, the protein content in the fiber can be maintained at a high level of 5.54 to 7.16%, and a milk protein-modified regenerated cellulose fiber with excellent dimensional stability and a shrinkage rate of less than 3% can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of cellulose fibers, and more specifically relates to a method for manufacturing regenerated cellulose fibers modified with milk protein.

Background Art

[0002] Cellulose fibers are manufactured using cellulose as a raw material, and have advantages such as excellent hygroscopicity, easy dyeing, and difficulty in becoming charged. They are widely used in fields such as clothing and textile products, and are utilized in the manufacture of underwear, outerwear, and various decorative supplies.

[0003] Milk protein mainly consists of casein and whey protein. Since its molecular structure contains various polar and non-polar amino acids, it has good biocompatibility and biodegradability. By adding it to fibers, the fibers can be made softer and more skin-friendly, and it also has the effect of promoting the metabolism of the human body.

[0004] However, milk protein has low biological stability. Since an acidic or alkaline environment exists during the manufacturing process of regenerated cellulose fibers, the structure and biological activity of milk protein are easily affected, resulting in a problem that the protein content in the actually obtained fibers is low. Due to the insufficient stability of milk protein, its application in the fiber field is limited.

[0005] In patent application number "CN201010184697.4" (invention name: "Milk protein blended regenerated cellulose fibers and their manufacturing method and uses"), milk protein is added to the viscose spinning dope. However, the protein is decomposed by the alkaline environment, resulting in a large waste of resources, a low protein content in the viscose fibers, and insufficient functionality.

[0006] Furthermore, in patent application number "CN21310528000.4" (title of invention: "Milk Protein / Bamboo Charcoal Viscose Fiber and Method for Producing the Same"), milk protein is adsorbed using the adsorption properties of bamboo charcoal. However, this method fails to address the effects of acidic and alkaline environments on milk protein, and also suffers from problems such as difficult operation, high process costs, and significant impact on the textile product.

[0007] Furthermore, the binding strength between milk protein and fiber is insufficient, resulting in low binding affinity. Consequently, after multiple washes, the protein content in the fiber decreases significantly, leading to a lack of sustained functionality. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Chinese Patent Application Number CN201010184697.4 [Patent Document 2] Chinese Patent Application Number CN21310528000.4 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] To solve the problems described above in the prior art, the present invention provides a method for producing milk protein-modified regenerated cellulose fibers, with the aim of improving the stability of milk protein and improving the binding properties between milk protein and fiber. [Means for solving the problem]

[0010] To solve the above technical problems, the present invention employs the following technical means. A method for producing milk protein-modified regenerated cellulose fiber, comprising the following steps:

[0011] S1: Preparation of cyclic intermediate Whey protein peptides are dissolved in dimethyl sulfoxide to obtain a whey protein peptide solution. The whey protein peptide solution is placed in an ice bath, a condensing agent is added to the whey protein peptide solution and stirred for 5-10 minutes, and then the accelerator N,N-diisopropylethylamine is added to the whey protein peptide solution and stirred for another 5-10 minutes. The ice bath is removed and the reaction is allowed to proceed at room temperature for 24-36 hours. After the reaction is complete, hydrochloric acid solution is added to stop the reaction, and after extraction, the product is sequentially washed with saturated sodium bicarbonate solution and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography to obtain cyclic milk protein.

[0012] Preferably, the mass ratio of the whey protein peptide to dimethyl sulfoxide is 1:12 to 15.

[0013] Preferably, the temperature of the ice bath is 0 to 5°C.

[0014] Preferably, the condensing agent is a mixture of HATU and HOAt, and the molar ratio of the whey protein peptide, HATU, and HOAt is 1:1 to 3:1 to 3.

[0015] Preferably, the molar ratio of the whey protein peptide to N,N-diisopropylethylamine is 1:3 to 4.

[0016] Preferably, the concentration of the hydrochloric acid solution is 0.1 mol / L, and the amount added is 50-60% of the mass of the whey protein peptide solution.

[0017] S2: Preparation of modified cyclic milk protein Cyclic milk protein is dissolved in tetrahydrofuran, and triethylamine, an acid scavenger, is added. The mixture is stirred for 10-20 minutes under nitrogen protection. Acryloyl chloride is slowly added under ice bath conditions and the mixture is reacted for 12-16 hours. The hydroxyl groups of cyclic milk protein are esterified with acryloyl chloride, and unsaturated double bonds are grafted onto some of the hydroxyl groups of the cyclic milk protein, yielding cyclic milk protein acrylate. After the reaction is complete, the mixture is concentrated, extracted with ethyl acetate, washed with saturated sodium chloride solution, concentrated under reduced pressure, and dried to obtain modified cyclic milk protein.

[0018] Preferably, the amount of triethylamine added is 10-13% of the mass of cyclic milk protein, and the amount of acryloyl chloride added is 30-36% of the mass of cyclic milk protein.

[0019] Preferably, the temperature of the ice bath is 0 to 5°C.

[0020] Whey protein peptides are hydrolysis products of whey protein, and their structure is a linear peptide structure with an N-terminus and a C-terminus in the peptide chain. Using whey protein peptides as a raw material, the N-terminus and C-terminus of the peptide chain are condensed using a condensing agent to form an amide bond and link them, thereby obtaining a cyclic milk protein having an amide ring structure. The cyclic milk protein contains numerous hydroxyl groups, and some of these hydroxyl groups undergo esterification with acryloyl chloride to obtain cyclic milk protein acrylate, i.e., modified cyclic milk protein.

[0021] S3: Preparation of spinning solution The pulp raw material is immersed in a sodium hydroxide solution with a mass fraction of 14-18% at a temperature of 50-60°C for 40-60 minutes. The alkaline solution dissolves the low-molecular-weight hemicellulose, yielding an insoluble portion, which is designated as α-cellulose.

[0022] Press the α-cellulose to obtain alkali cellulose with a diameter of 15-20 μm. After pulverization, aging treatment is carried out. The aging temperature is 20-25 °C, and the aging time is 1.5-2 hours. After aging, 30-40% of the mass of α-cellulose of CS2 is added and mixed to carry out a yellowing reaction. The yellowing temperature is 15-20 °C, and the yellowing time is 30-60 minutes to produce cellulose xanthate. Dissolve the cellulose xanthate in a sodium hydroxide solution with a mass fraction of 4-8%, and successively carry out dissolution, filtration, defoaming, and aging. The aging time is 12-24 hours, and the aging temperature is 15-20 °C to obtain a spinning dope.

[0023] Preferably, the viscosity of the spinning dope is controlled to be 55-65 seconds (falling ball method), the degree of aging is controlled to be 10-14 mL (10% NH4Cl), the NaOH content is 3.5-5.0 wt%, and the methyl cellulose (MC) content is 8.2-9.4 wt%.

[0024] S4: Blending Add the modified cyclic milk protein into the spinning dope and stir for 20-30 minutes. Then, add ammonium cerium nitrate, heat up to 30-40 °C and react for 60-80 minutes to graft the modified cyclic milk protein onto the cellulose polymer to obtain a blended spinning dope.

[0025] Preferably, the addition amount of the modified cyclic milk protein is 8-10% of the methyl cellulose (MC) content in the spinning dope.

[0026] Preferably, the addition amount of the ammonium cerium nitrate is 2-3% of the modified cyclic milk protein.

[0027] S5: Spinning In a spinning machine, the co-blended yarn stock is extruded from the spindle and passed through a coagulation bath to obtain a bundle of primary fibers. The bundle of primary fibers is shaped by spindle draw of 30-60%, spinning wheel draw of 40-60%, convergence draw of 10-30%, and -2--1% re-shrunk draw. After desulfurization, washing, application of oil, drying, and opening, milk protein modified regenerated cellulose fibers are obtained.

[0028] Preferably, the composition of the coagulation bath is 120-170 g / L of sulfuric acid, 35-50 g / L of zinc sulfate, and 230-260 g / L of sodium sulfate, the reaction temperature is 40-50°C, and the spinning rate is 30-80 m / min.

[0029] Preferably, the concentration of Na2S in the desulfurization is 2.5 to 3.5 g / L, and the concentration of urea is 0.5 to 1 g / L.

[0030] Preferably, in the application of the oil, the oil is SJ-718, and the amount used is 1-2% of the oven-dry mass of the fiber. [Effects of the Invention]

[0031] By employing the above technical means, the present invention achieves the following technical effects.

[0032] 1. The milk protein-modified regenerated cellulose fiber obtained by the present invention has a high protein content, accounting for 5.54-7.16% of the fiber mass.

[0033] 2. The milk protein-modified regenerated cellulose fibers obtained by the present invention have excellent mechanical properties, with a dry tensile strength of 2.84 to 3.15 cN / dtex and a wet tensile strength of 1.96 to 2.18 cN / dtex.

[0034] 3. The milk protein-modified regenerated cellulose fiber obtained by the present invention has good hygroscopicity, and its tide return rate is 14.3-15.1%.

[0035] 4. Using whey protein peptides extracted from milk as a raw material, a condensing agent is used to condense the N-terminus and C-terminus of the peptide chain to form and link amide bonds, thereby obtaining a cyclic milk protein having an amide ring structure. Some of the numerous hydroxyl groups in the cyclic milk protein are esterified with acryloyl chloride to obtain cyclic milk protein-acrylate, i.e., modified milk protein. Here, because the amide ring structure is more stable, the modified milk protein is less likely to decompose or precipitate in alkaline spinning solutions and acidic coagulation baths, thereby improving the protein content in the fiber.

[0036] 5. The modified milk protein is modified with acrylate, and under the action of cerium ammonium nitrate, it is further grafted with cellulose polymers, which not only improves the mechanical strength and dimensional stability of the fibers, but also strengthens the bond between the protein and fibers through chemical bonding, maintaining a high level of protein content in the fibers even after multiple washes.

[0037] 6. The milk protein-modified regenerated cellulose fibers obtained by the present invention have good dimensional stability and a shrinkage rate of less than 3%. [Modes for carrying out the invention]

[0038] The present invention will be further described below with reference to specific examples.

[0039] Example 1 A method for producing milk protein-modified regenerated cellulose fiber, comprising the following steps:

[0040] S1: Preparation of cyclic intermediate Whey protein peptide was dissolved in dimethyl sulfoxide to obtain a whey protein peptide solution. The whey protein peptide solution was placed in an ice bath, a condensing agent was added to the whey protein peptide solution and stirred for 8 minutes, and then the accelerator N,N-diisopropylethylamine was added to the whey protein peptide solution and stirred for 8 minutes. The ice bath was removed and the reaction was allowed to proceed at room temperature for 30 hours. After the reaction was complete, hydrochloric acid solution was added to stop the reaction, and after extraction, the product was sequentially washed with saturated sodium bicarbonate solution and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography to obtain cyclic milk protein.

[0041] The mass ratio of the whey protein peptide to dimethyl sulfoxide was 1:13.

[0042] The temperature of the ice bath was 0°C.

[0043] The condensing agent was a mixture of HATU and HOAt, and the molar ratio of the whey protein peptide, HATU, and HOAt was 1:2:2.

[0044] The molar ratio of the whey protein peptide to N,N-diisopropylethylamine was 1:3.5.

[0045] The concentration of the hydrochloric acid solution was 0.1 mol / L, and the amount added was 55% of the mass of the whey protein peptide solution.

[0046] S2: Preparation of modified cyclic milk protein Cyclic milk protein was dissolved in tetrahydrofuran, and triethylamine, an acid scavenger, was added. The mixture was stirred for 15 minutes under nitrogen protection. Acryloyl chloride was slowly added under ice bath conditions and the mixture was reacted for 14 hours. The hydroxyl groups of cyclic milk protein were esterified with acryloyl chloride, and unsaturated double bonds were grafted onto some of the hydroxyl groups of the cyclic milk protein, yielding cyclic milk protein acrylate. After the reaction was complete, the mixture was concentrated, extracted with ethyl acetate, washed with saturated sodium chloride solution, concentrated under reduced pressure, and dried to obtain modified cyclic milk protein.

[0047] The amount of triethylamine added was 12% of the mass of cyclic milk protein, and the amount of acryloyl chloride added was 34% of the mass of cyclic milk protein.

[0048] The temperature of the ice bath was 0°C.

[0049] S3: Preparation of spinning solution Bamboo pulp was immersed in a sodium hydroxide solution with a mass fraction of 16% at 55°C for 50 minutes. The alkaline solution dissolved the low-molecular-weight hemicellulose, yielding an insoluble portion, which was identified as α-cellulose.

[0050] Alkali cellulose with a diameter of 15 μm was obtained by pressing α-cellulose, which was then ground and subjected to aging treatment. The aging temperature was 23°C and the aging time was 2 hours. After aging, 35% of the mass of α-cellulose CS2 was added and mixed, and a yellowing reaction was carried out. The yellowing temperature was 18°C ​​and the yellowing time was 50 minutes, producing cellulose xanthogenic acid ester. The cellulose xanthogenic acid ester was dissolved in a 6% by mass sodium hydroxide solution, and dissolution, filtration, defoaming, and aging were carried out sequentially. The aging time was 20 hours and the aging temperature was 18°C ​​to obtain a spinning solution.

[0051] The viscosity of the spinning solution was controlled to 60 seconds (ball drop method), the maturity level was controlled to 13 mL (10% NH4Cl), the NaOH content was 4 wt%, and the methylcellulose content was 8.8 wt%.

[0052] S4: Comixture The modified cyclic milk protein was added to the spinning solution and stirred for 25 minutes, then cerium ammonium nitrate was added, and the temperature was raised to 35°C and the reaction was carried out for 70 minutes to graft the modified cyclic milk protein onto the cellulose polymer, obtaining a comixed spinning solution.

[0053] The amount of modified cyclic milk protein added was 9% of the methylcellulose content in the spinning solution.

[0054] The amount of cerium ammonium nitrate added was 2.5% of the modified cyclic milk protein.

[0055] S5: Spinning In a spinning machine, the co-blended yarn solution was extruded from the spindle and passed through a coagulation bath to obtain primary fiber bundles. The primary fiber bundles were then shaped by 40% spindle draw, 50% spinning wheel draw, 15% convergence draw, and -2% re-shrunk draw. After desulfurization, washing, oil application, drying, and fiber opening, milk protein modified regenerated cellulose fibers were obtained.

[0056] The coagulation bath consisted of 150 g / L of sulfuric acid, 40 g / L of zinc sulfate, and 240 g / L of sodium sulfate. The reaction temperature was 45°C, and the spinning rate was 60 m / min.

[0057] The concentration of Na2S in the desulfurization process was 3 g / L, and the concentration of urea was 0.8 g / L.

[0058] In the application of the oiling agent, SJ-718 was used, and its amount was 1.5% of the absolute dry mass of the fiber.

[0059] Example 2 A method for producing milk protein-modified regenerated cellulose fiber, comprising the following steps:

[0060] S1: Preparation of cyclic intermediate Whey protein peptide was dissolved in dimethyl sulfoxide to obtain a whey protein peptide solution. The whey protein peptide solution was placed in an ice bath, a condensing agent was added to the whey protein peptide solution and stirred for 5 minutes, and then the accelerator N,N-diisopropylethylamine was added to the whey protein peptide solution and stirred for 10 minutes. The ice bath was removed and the reaction was allowed to proceed at room temperature for 24 hours. After the reaction was complete, hydrochloric acid solution was added to stop the reaction, and after extraction, the product was sequentially washed with saturated sodium bicarbonate solution and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography to obtain cyclic milk protein.

[0061] The mass ratio of the whey protein peptide to dimethyl sulfoxide was 1:12.

[0062] The temperature of the ice bath was 5°C.

[0063] The condensing agent was a mixture of HATU and HOAt, and the molar ratio of the whey protein peptide, HATU, and HOAt was 1:1:3.

[0064] The molar ratio of the whey protein peptide to N,N-diisopropylethylamine was 1:3.

[0065] The concentration of the hydrochloric acid solution was 0.1 mol / L, and the amount added was 50% of the mass of the whey protein peptide solution.

[0066] S2: Preparation of modified cyclic milk protein Cyclic milk protein was dissolved in tetrahydrofuran, and triethylamine, an acid scavenger, was added. The mixture was stirred for 10 minutes under nitrogen protection. Acryloyl chloride was slowly added under ice bath conditions and the mixture was reacted for 12 hours. The hydroxyl groups of cyclic milk protein were esterified with acryloyl chloride, and unsaturated double bonds were grafted onto some of the hydroxyl groups of the cyclic milk protein, yielding cyclic milk protein acrylate. After the reaction was complete, the mixture was concentrated, extracted with ethyl acetate, washed with saturated sodium chloride solution, concentrated under reduced pressure, and dried to obtain modified cyclic milk protein.

[0067] The amount of triethylamine added was 10% of the mass of cyclic milk protein, and the amount of acryloyl chloride added was 30% of the mass of cyclic milk protein. The temperature of the ice bath was 5°C.

[0068] S3: Preparation of spinning solution Bamboo pulp was immersed in a sodium hydroxide solution with a mass fraction of 14% at 50°C for 60 minutes. The alkaline solution dissolved the low-molecular-weight hemicellulose, yielding an insoluble portion, which was identified as α-cellulose.

[0069] Alkali cellulose with a diameter of 20 μm was obtained by pressing α-cellulose, which was then ground and subjected to aging treatment. The aging temperature was 20°C and the aging time was 1.5 hours. After aging, 30% of the mass of α-cellulose in CS2 was added and mixed, and a yellowing reaction was carried out. The yellowing temperature was 15°C and the yellowing time was 30 minutes, producing cellulose xanthogenic acid ester. The cellulose xanthogenic acid ester was dissolved in a 4% by mass sodium hydroxide solution, and dissolution, filtration, defoaming, and aging were carried out sequentially. The aging time was 12 hours and the aging temperature was 15°C to obtain a spinning solution.

[0070] The viscosity of the spinning solution was controlled to 55 seconds (ball drop method), the maturity level was controlled to 10 mL (10% NH4Cl), the NaOH content was 3.5 wt%, and the methylcellulose content was 8.2 wt%.

[0071] S4: Comixture The modified cyclic milk protein was added to the spinning solution and stirred for 20 minutes, then cerium ammonium nitrate was added, and the temperature was raised to 30°C and the reaction was carried out for 60 minutes to graft the modified cyclic milk protein onto the cellulose polymer, obtaining a co-mixed spinning solution.

[0072] The amount of modified cyclic milk protein added was 8% of the methylcellulose content in the spinning solution.

[0073] The amount of cerium ammonium nitrate added was 2% of the modified cyclic milk protein.

[0074] S5: Spinning In a spinning machine, the co-blended yarn solution was extruded from the spindle and passed through a coagulation bath to obtain primary fiber bundles. The primary fiber bundles were then shaped by 30% spindle draw, 60% spinning wheel draw, 10% convergence draw, and -1% re-shrunk draw. After desulfurization, washing, oil application, drying, and fiber opening, milk protein modified regenerated cellulose fibers were obtained.

[0075] The coagulation bath consisted of 120 g / L of sulfuric acid, 50 g / L of zinc sulfate, and 230 g / L of sodium sulfate. The reaction temperature was 40°C, and the spinning rate was 30 m / min.

[0076] The concentration of Na2S in the desulfurization process was 2.5 g / L, and the concentration of urea was 0.5 g / L.

[0077] In the application of the oiling agent, SJ-718 was used, and the amount used was 1% of the absolute dry mass of the fiber.

[0078] Example 3 A method for producing milk protein-modified regenerated cellulose fiber, comprising the following steps:

[0079] S1: Preparation of cyclic intermediate Whey protein peptides were dissolved in dimethyl sulfoxide to obtain a whey protein peptide solution. The whey protein peptide solution was placed in an ice bath, a condensing agent was added to the whey protein peptide solution and stirred for 10 minutes, and then the accelerator N,N-diisopropylethylamine was added to the whey protein peptide solution and stirred for 5 minutes. The ice bath was removed and the mixture was allowed to react at room temperature for 36 hours. After the reaction was complete, hydrochloric acid solution was added to stop the reaction, and after extraction, the product was sequentially washed with saturated sodium bicarbonate solution and saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography to obtain cyclic milk protein.

[0080] The mass ratio of the whey protein peptide to dimethyl sulfoxide was 1:15.

[0081] The temperature of the ice bath was 2°C.

[0082] The condensing agent was a mixture of HATU and HOAt, and the molar ratio of the whey protein peptide, HATU, and HOAt was 1:3:1.

[0083] The molar ratio of the whey protein peptide to N,N-diisopropylethylamine was 1:4.

[0084] The concentration of the hydrochloric acid solution was 0.1 mol / L, and the amount added was 60% of the mass of the whey protein peptide solution.

[0085] S2: Preparation of modified cyclic milk protein Cyclic milk protein was dissolved in tetrahydrofuran, and triethylamine, an acid scavenger, was added. The mixture was stirred for 20 minutes under nitrogen protection. Acryloyl chloride was slowly added under ice bath conditions and the mixture was reacted for 16 hours. The hydroxyl groups of cyclic milk protein were esterified with acryloyl chloride, and unsaturated double bonds were grafted onto some of the hydroxyl groups of the cyclic milk protein, yielding cyclic milk protein acrylate. After the reaction was complete, the mixture was concentrated, extracted with ethyl acetate, washed with saturated sodium chloride solution, concentrated under reduced pressure, and dried to obtain modified cyclic milk protein.

[0086] The amount of triethylamine added was 13% of the mass of cyclic milk protein, and the amount of acryloyl chloride added was 36% of the mass of cyclic milk protein.

[0087] The temperature of the ice bath was 2°C.

[0088] S3: Preparation of spinning solution Bamboo pulp was immersed in a sodium hydroxide solution with a mass fraction of 18% at 60°C for 40 minutes. The alkaline solution dissolved the low-molecular-weight hemicellulose, yielding an insoluble portion, which was identified as α-cellulose.

[0089] Alkali cellulose with a diameter of 18 μm was obtained by pressing α-cellulose, which was then ground and subjected to aging treatment. The aging temperature was 25°C and the aging time was 2 hours. After aging, 40% of the mass of α-cellulose in CS2 was added and mixed, and a yellowing reaction was carried out. The yellowing temperature was 20°C and the yellowing time was 60 minutes, producing cellulose xanthogenic acid ester. The cellulose xanthogenic acid ester was dissolved in an 8% sodium hydroxide solution by mass fraction, and dissolution, filtration, defoaming, and aging were carried out sequentially. The aging time was 24 hours and the aging temperature was 20°C to obtain a spinning solution.

[0090] The viscosity of the spinning solution was controlled to 65 seconds (ball drop method), the maturity level was controlled to 14 mL (10% NH4Cl), the NaOH content was 5.0 wt%, and the methylcellulose content was 9.4 wt%.

[0091] S4: Comixture Modified cyclic milk protein was added to the spinning solution and stirred for 30 minutes, then cerium ammonium nitrate was added, and the temperature was raised to 40°C and the reaction was carried out for 80 minutes to graft the modified cyclic milk protein onto the cellulose polymer, obtaining a comixed spinning solution.

[0092] The amount of modified cyclic milk protein added was 10% of the methylcellulose content in the spinning solution.

[0093] The amount of cerium ammonium nitrate added was 3% of the modified cyclic milk protein.

[0094] S5: Spinning In a spinning machine, the co-blended yarn solution was extruded from the spindle and passed through a coagulation bath to obtain primary fiber bundles. The primary fiber bundles were shaped by 60% spindle draw, 40% spinning wheel draw, 10% convergence draw, and -1% re-shrunk draw. After desulfurization, washing, oil application, drying, and fiber opening, milk protein modified regenerated cellulose fibers were obtained.

[0095] The coagulation bath consisted of 170 g / L of sulfuric acid, 35 g / L of zinc sulfate, and 260 g / L of sodium sulfate. The reaction temperature was 50°C, and the spinning rate was 80 m / min.

[0096] The concentration of Na2S in the desulfurization process was 3.5 g / L, and the concentration of urea was 1 g / L.

[0097] In the application of the oil, the oil used was SJ-718, and the amount used was 2% of the absolute dry mass of the fiber.

[0098] Comparative Example 1 As a representative example, we selected Example 1 and made it identical to Example 1 except that we omitted step S2 and directly added equal proportions of cyclic milk protein to the spinning solution. This was designated as Comparative Example 1.

[0099] Comparative Example 2 Comparative Example 2 was created by replacing the cyclic milk protein in Comparative Example 1 with an equal amount of whey protein and adding it to the spinning solution, making it identical to Comparative Example 1.

[0100] The cellulose fibers obtained in the examples and comparative examples were evaluated for their physical properties, and the results are shown in Table 1. Table 1 As is clear from Table 1, the milk protein-modified regenerated cellulose fibers obtained in Examples 1-3 have a high protein content, stable protein properties, and a decrease in protein content in the fibers after 50 washes of water is less than 5%. In addition, they have excellent mechanical properties, good dimensional stability, and high hygroscopicity.

[0101] In Comparative Example 1, the S2 step was omitted, and cyclic milk protein was added directly to the spinning solution, resulting in a decrease in fiber strength, particularly a significant decrease in wet tensile strength. Furthermore, the rate of decrease in protein content and shrinkage rate in the fibers after 50 washes increased. This is because the inclusion of acrylate in the modified cyclic milk protein improved the graft bonding effect with the fibers, and the introduction of acrylate further improved fiber strength and reduced shrinkage rate. On the other hand, because acrylate is hydrophobic, the desiccation rate of Comparative Example 1 increased slightly.

[0102] In Comparative Example 2, compared to Comparative Example 1, all of the fiber properties were reduced, and in particular, the protein content decreased significantly. This indicates that cyclic milk protein is more stable, less affected by acidic and alkaline environments, can prevent a decrease in protein content in the fiber, and is less likely to adversely affect the mechanical properties of the fiber.

[0103] Unless otherwise specified, all proportions and percentages mentioned in this invention are mass proportions. Furthermore, all raw materials used are commercially available.

[0104] In conclusion, the above description illustrates preferred embodiments of the present invention and does not limit it. Those skilled in the art can make various modifications, equivalent substitutions, or improvements to the technical configurations described in each of the embodiments within the spirit and principles of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A method for producing milk protein-modified regenerated cellulose fiber, The above manufacturing method includes a step for manufacturing a cyclic intermediate, a step for manufacturing modified cyclic milk protein, a step for manufacturing a spinning stock, a co-mixing step, and a spinning step, The modified cyclic milk protein is a cyclic milk protein-acrylate having an amide ring structure and an acrylate group. The aforementioned co-mixing step, The process involves adding modified cyclic milk protein to the spinning solution and stirring for 20-30 minutes, then adding cerium ammonium nitrate, raising the temperature to 30-40°C, and reacting for 60-80 minutes to graft the modified cyclic milk protein onto cellulose polymers to obtain a co-mixed spinning solution. The amount of the modified cyclic milk protein added is 8-10% of the methylcellulose content in the spinning solution. The amount of cerium ammonium nitrate added is characterized by being 2-3% of the modified cyclic milk protein. A method for producing regenerated cellulose fiber modified from milk protein.

2. The manufacturing process for the aforementioned cyclic intermediate is, A step of dissolving whey protein peptides in dimethyl sulfoxide to obtain a whey protein peptide solution. The whey protein peptide solution is placed under an ice bath, a condensing agent is added and stirred for 5 to 10 minutes, then the accelerator N,N-diisopropylethylamine is added and stirred for 5 to 10 minutes, after which the ice bath is removed and the reaction is carried out at room temperature for 24 to 36 hours. After the reaction is complete, hydrochloric acid solution is added to stop the reaction. After extraction, the product is sequentially washed with saturated sodium bicarbonate aqueous solution and saturated saline solution, dried with anhydrous sodium sulfate, filtered and concentrated, and then purified by silica gel column chromatography to obtain cyclic milk protein. A method for producing milk protein-modified regenerated cellulose fiber according to claim 1, characterized by including the following:

3. The mass ratio of the whey protein peptide to dimethyl sulfoxide is 1:12 to 15. The method for producing milk protein-modified regenerated cellulose fibers according to claim 2, characterized in that the temperature of the ice bath is 0 to 5°C.

4. The condensing agent is a mixture of HATU and HOAt, and the molar ratio of whey protein peptide, HATU, and HOAt is 1:1 to 3:1 to 3. The molar ratio of the whey protein peptide to N,N-diisopropylethylamine is 1:3 to 4. The method for producing milk protein-modified regenerated cellulose fibers according to claim 2, characterized in that the concentration of the hydrochloric acid solution is 0.1 mol / L and the amount added is 50 to 60% of the mass of the whey protein peptide solution.

5. The above-mentioned process for producing modified cyclic milk protein is, Cyclic milk protein is dissolved in tetrahydrofuran, triethylamine, an acid scavenger, is added, and the mixture is stirred under a nitrogen atmosphere for 10-20 minutes. Then, acryloyl chloride is gradually added under an ice bath and the mixture is reacted for 12-16 hours. A process to obtain cyclic milk protein-acrylate by esterifying the hydroxyl groups of cyclic milk protein with acryloyl chloride to introduce unsaturated double bonds to some of the hydroxyl groups of cyclic milk protein. The process involves concentrating the solution after the reaction is complete, extracting it with ethyl acetate, washing it with saturated sodium chloride aqueous solution, and then concentrating it under reduced pressure and drying it. A method for producing milk protein-modified regenerated cellulose fiber according to claim 1, characterized by including the following:

6. The amount of triethylamine added is 10 to 13% of the mass of cyclic milk protein. The amount of acryloyl chloride added is 30-36% of the mass of cyclic milk protein. The method for producing milk protein-modified regenerated cellulose fibers according to claim 5, characterized in that the temperature of the ice bath is 0 to 5°C.

7. The manufacturing process of the aforementioned spinning solution, This process involves soaking, pressing, crushing, aging, yellowing, dissolving, filtering, defoaming, and maturing pulp raw materials to obtain spinning solution. The viscosity of the spinning solution is 55-65 seconds (ball drop method), and the degree of maturity is 10-14 mL (10% NH₄). ４ A method for producing milk protein-modified regenerated cellulose fiber according to claim 1, characterized in that the Cl) and NaOH content is 3.5 to 5.0 wt%, and the methylcellulose content is 8.2 to 9.4 wt%.

8. The aforementioned spinning process, The process involves extruding the co-blended yarn stock from the spinning machine's nozzle and passing it through a coagulation bath to obtain primary fiber yarn. The aforementioned primary fiber yarn is shaped by subjecting it to spinneret draw of 30-60%, spinneret draw of 40-60%, convergence draw of 10-30%, and re-shortening draw of -2-1%. The process involves desulfurization, washing, lubrication, drying, and fiber opening. A method for producing milk protein-modified regenerated cellulose fiber according to claim 1, characterized by including the following:

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