A method for preparing PA6 fluorescent powder

Abstract

The invention belongs to the field of polymer materials and relates to a preparation method of PA6 fluorescent powder. After a modified liquid containing soybean protein isolate, corn starch, ethyl acetate and water is ground and mixed with silicon dioxide, heat treatment is first performed to denature the soybean protein isolate, and then freeze-drying is performed to obtain modified silicon dioxide. Subsequently, the modified silicon dioxide is used to load curcumin. Finally, the modified silicon dioxide loaded with curcumin and PA6 are compounded in a solvent by a dissolution precipitation method. The finally prepared PA6 fluorescent powder has a high curcumin loading amount and a good fluorescent effect, and the application field of the PA6 powder is effectively broadened. In addition, the preparation method has easy-to-obtain raw materials, simple steps, low cost, and is suitable for large-scale application.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and relates to a method for preparing PA6 fluorescent powder. Background Art

[0002] PA6 (polyamide 6, nylon 6) is a type of high molecular polymer formed by the ring-opening polymerization of caprolactam. It has excellent mechanical properties and chemical inertness, so it is widely used. PA6 powder has a wide operating temperature and good impact resistance. It has been used in adhesives, fillers, coatings and other fields. For example, PA6 fluorescent powder is used for fingerprint display and anti-counterfeiting purposes. However, the molecular chain of PA6 material contains repeated amide bonds and has a high hygroscopicity. Therefore, the dimensional stability of PA6 material is poor, so it is of great significance to study the dimensionally stable PA6 fluorescent powder.

[0003] The existing technology modifies PA6 by adding inorganic fillers such as silica, which is beneficial to improving the dimensional stability of PA6.

[0004] Curcumin is a type of natural phenolic antioxidant extracted from the rhizomes of turmeric, mustard, curry and other plants of the ginger family. It has fluorescent properties, and the use of curcumin to prepare PA6 fluorescent materials has important application prospects.

[0005] However, curcumin has poor water solubility and is difficult to evenly combine with materials such as silica and PA6 without using a carrier. Even after curcumin is loaded with a carrier, it is still difficult to evenly combine with silica and PA6.

[0006] For example, Reference 1 (Preparation of Zein-Sodium Alginate Nanoparticles and Study on Their Loading of Curcumin [J]. Chinese Food Additives, 2024, 35(3):25-34.) uses an antisolvent method to prepare zein-sodium alginate particles for loading curcumin, in which hydrogen bonds and hydrophobic effects are the main driving forces for the combination of sodium alginate and zein. Zein is embedded in curcumin, and sodium alginate is used to coat it, which increases the encapsulation rate of curcumin and improves the photothermal stability and thermal stability of curcumin. However, the curcumin-loaded nanomaterials in this document cannot be combined with other materials, which limits its scope of application.

[0007] For example, in reference 2 (Effects of plasma-assisted treatment on the structure and functional properties of chickpea starch-curcumin complex [J]. Journal of Food Safety and Quality, 2023, 14(24):264-271.), starch extracted from chickpeas is modified by plasma to have more active groups on its surface to form a starch-curcumin complex. The introduction of curcumin can inhibit the activity of amylase and regulate the function of intestinal flora. Starch is a good curcumin carrier and can generally form a complex through blending, heating, adsorption, encapsulation and other methods. However, the starch-curcumin complex in this document is also difficult to combine with other materials.

[0008] Therefore, it is necessary to study a new method for preparing PA6 fluorescent powder using silica and curcumin to achieve uniform combination of curcumin with silica and PA6. Summary of the invention

[0009] The purpose of the present invention is to solve the above problems existing in the prior art and provide a method for preparing PA6 fluorescent powder.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing PA6 fluorescent powder comprises grinding and mixing a modified liquid containing soy protein isolate, corn starch, ethyl acetate and water with silicon dioxide, firstly heat-treating the soy protein isolate to denature it, then freeze-drying it to obtain modified silicon dioxide, then using the modified silicon dioxide to load curcumin, and finally compounding the modified silicon dioxide loaded with curcumin and PA6 in a solvent by a dissolution precipitation method to obtain PA6 fluorescent powder;

[0012] The principle of the present invention is as follows:

[0013] The compounding of silicon dioxide and PA6 can further improve the dimensional stability of PA6. The present invention attempts to introduce silicon dioxide and curcumin into PA6 powder at the same time. However, silicon dioxide cannot directly load curcumin. The present invention uses protein denaturation to form a "shell" with soy protein isolate to tightly fix silicon dioxide therein. Since soy protein isolate is an excellent carrier of curcumin, it can adsorb and bind curcumin, thereby obtaining modified silicon dioxide loaded with curcumin. Then, the modified silicon dioxide is used as the core to successfully prepare PA6 fluorescent powder by dissolution precipitation method.

[0014] If the "sheath" has a large number of holes, the adsorption of curcumin can be further enhanced. In the process of forming the "sheath", corn starch is introduced into the present invention. Corn starch has high water absorption and can absorb a large amount of water. A large number of holes can be formed after freeze drying, thereby enhancing the adsorption of curcumin. Due to the hydrophobic effect between soy protein isolate and corn starch, the two can produce more serious agglomeration in the modified liquid, which is not conducive to the combination of soy protein isolate and silicon dioxide. Ethyl acetate can play a lubricating role between soy protein isolate and corn starch, weaken the acting force and contact area between the two, so that the two have good fluidity after mixing, which is conducive to the combination of soy protein isolate and silicon dioxide. The effect of ethyl acetate is as follows: Figure 1 shown.

[0015] The protein used in Document 1 and the starch used in Document 2 are both good carriers of curcumin, but starch cannot form a tight bond with silica, and pure protein cannot form a "shell" on the surface of silica after grinding with silica, because pure protein forms uneven bumps on the surface of silica and cannot completely wrap the silica.

[0016] As the preferred technical solution:

[0017] In the preparation method of the PA6 fluorescent powder as described above, the modified liquid also contains disodium hydrogen phosphate and PVP (polyvinyl pyrrolidone). The better the water retention performance of corn starch is, the more conducive it is to form pores and adsorb curcumin. In order to improve the water retention performance of corn starch, the present invention also introduces disodium hydrogen phosphate and PVP in the process of forming the "shell". Disodium hydrogen phosphate, as a water-retaining agent, can enable corn starch to retain hygroscopic moisture so as to produce more pores; PVP can combine disodium hydrogen phosphate with water through hydrogen bonds. The role of PVP is as follows: Figure 1 As shown; in addition, during the cooling process of freeze-drying, the molecular chains of PVP can curl, so that the water molecules and disodium hydrogen phosphate are more tightly combined with corn starch. A part of the space originally occupied by water molecules and disodium hydrogen phosphate under the high temperature of heat treatment is released, forming a hierarchical structure of soy protein isolate, PVP, water, disodium hydrogen phosphate, ethyl acetate, and corn starch, which increases the deformation of the modified substance caused by external force during the grinding process, and the surface area of ​​the covered silicon dioxide is larger, thereby increasing the contact area between the modified substance and silicon dioxide, making it easier for the modified substance to combine and cover silicon dioxide, similar to pressing a sponge and plasticine, the sponge has a greater degree of deformation and a larger specific surface area.

[0018] In the preparation method of the PA6 fluorescent powder as described above, the preparation process of the modified liquid is: after mixing the soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP in water, stirring at 55-60° C. for 1.5-2 hours.

[0019] In the preparation method of PA6 fluorescent powder as described above, the mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate and PVP is 5~5.5:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate and PVP in the modified liquid is 80~82wt%.

[0020] In the preparation method of PA6 fluorescent powder as described above, the mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to the mass ratio of silicon dioxide is 1:1.

[0021] In the preparation method of the PA6 fluorescent powder as described above, the grinding temperature is 20-25°C and the grinding time is 5-6 minutes.

[0022] In the preparation method of the PA6 fluorescent powder as described above, the heat treatment is carried out by steam treatment, and the heat treatment time is 60 to 70 minutes.

[0023] In the preparation method of the PA6 fluorescent powder as described above, the freeze-drying process is: first freeze at -70°C for 48 to 50 hours, then keep the temperature constant and freeze at a vacuum degree of 2 to 2.5 Pa for 48 to 50 hours.

[0024] The preparation method of a PA6 fluorescent powder as described above, using modified silica to load curcumin means: the modified silica is immersed in an ethanol solution of curcumin and then dried, wherein the concentration of the ethanol solution of curcumin is 0.5~1wt%, the mass ratio of the modified silica to the ethanol solution of curcumin is 1:40~50, the immersion temperature is 30~40℃, the time is 5~10min, and the drying is carried out by vacuum drying, the drying temperature is 60℃, and the time is 24h.

[0025] The preparation method of the PA6 fluorescent powder as described above, wherein the modified silica loaded with curcumin and PA6 are compounded in a solvent by a dissolution precipitation method, refers to: after the modified silica loaded with curcumin, PA6 and water are mixed, the temperature is raised to 160-162°C and then kept warm for 24-26 hours, and then the temperature is lowered to 20-25°C, and then post-processed (the post-processing process is: vacuum drying, the drying temperature is 60°C, and the time is 24 hours), wherein the mass ratio of the modified silica loaded with curcumin, PA6, and water is 0.2-0.3:1.3:50-60, and the role of water is solvent, and PA6 is a good solvent under normal conditions. There are only a few solvents such as formic acid, trifluoroacetic acid, and meta-cresol. Although PA6 has a large number of amide bonds and has strong water absorption, water is still a poor solvent for PA6 at room temperature and pressure. However, in the supercritical and subcritical states, water has many properties that do not exist at room temperature, such as high fluidity, high ion product constant, and small dielectric constant. When the temperature rises, the hydrogen bonding between water molecules weakens, the fluidity increases, and it can enter the PA6 lattice, breaking the hydrogen bonding between PA6 molecular chains, so that PA6 can be dissolved in superheated water, and curcumin will not dissolve in water, thereby avoiding the diffusion of curcumin into water during the dissolution and precipitation process.

[0026] A method for preparing a PA6 fluorescent powder as described in any of the above items, wherein the yield of the PA6 fluorescent powder (yield = mass of PA6 fluorescent powder / mass of PA6 before dissolution + mass of modified silica × 100%) is 70%, the average particle size is 90~100μm, the encapsulation rate of curcumin is 68~92%, and the loading rate is 1.6~5.4%.

[0027] Beneficial effects:

[0028] (1) Silicon dioxide and curcumin are simultaneously introduced into the PA6 fluorescent powder prepared by the present invention, which not only improves the dimensional stability of PA6, but also uniformly combines curcumin with PA6. The curcumin loading amount is high and the fluorescent effect is good, which effectively broadens the application field of PA6 powder.

[0029] (2) The raw materials used in the present invention, such as soy protein isolate, silicon dioxide, and curcumin, are easily available, low in cost, and simple in steps, and are suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the principle of the preparation method of the present invention;

[0031] Figure 2 This is a SEM image of the PA6 fluorescent powder prepared in the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0033] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0034] (1) Yield of PA6 fluorescent powder:

[0035] Yield = mass of PA6 fluorescent powder / (mass of PA6 before dissolution + mass of modified silica) × 100%.

[0036] (2) Encapsulation rate and loading rate of curcumin:

[0037] PA6 fluorescent powder and deionized water were mixed at a mass ratio of 1:60 to form a PA6 fluorescent powder dispersion, and then the PA6 fluorescent powder dispersion was centrifuged at 15000r / min for 30min, 1mL of supernatant was added with 1mL of deionized water and 5mL of ethanol, and the mixture was extracted and mixed using a vortex machine; the absorbance of unencapsulated curcumin was measured at a wavelength of 426nm using a UV-visible spectrophotometer (UV-visible spectrophotometer provided by Beijing Puxi General Co., Ltd., model TU-1810); water and ethanol were mixed in a volume ratio of 1:5 as a solvent, and curcumin was used as a solute, and the curcumin concentration and 426nm were compared at 0.02mg / mL, 0.03mg / mL, 0.04mg / mL, 0.8mg / mL, 0.12mg / mL, and 0.16mg / mL. A standard curve of wavelength absorbance; the content of unencapsulated curcumin is calculated based on this standard curve, and then the encapsulation rate and loading rate of curcumin are calculated according to formulas (I) and (II);

[0038] (I) Embedding rate = (M1-M2) / M1×100%;

[0039] (II) Load rate = (M1-M2) / M0×100%;

[0040] Wherein: M1 is the mass of curcumin (that is, the total mass of the embedded curcumin and the unembedded curcumin); M2 is the mass of the unembedded curcumin; M0 is the mass of the PA6 fluorescent powder.

[0041] Example 1

[0042] A method for preparing PA6 fluorescent powder, the specific steps are as follows:

[0043] (1) Preparation of raw materials;

[0044] Soy protein isolate: CAS: 9010-10-0, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0045] Corn starch: CAS: 9005-25-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0046] Ethyl acetate;

[0047] Disodium hydrogen phosphate;

[0048] PVP: CAS: 9003-39-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0049] water;

[0050] Silicon dioxide: average particle size 50 nm, CAS: 7631-86-9, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0051] Curcumin: CAS: 458-37-7, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0052] Ethanol;

[0053] PA6;

[0054] (2) Preparation of modified liquid;

[0055] Soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP were mixed in water and stirred at 60°C for 2 hours to obtain a modified solution. The mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP was 5.5:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP in the modified solution was 82wt%; the effects of ethyl acetate and PVP were as follows: Figure 1 As shown;

[0056] (3) Preparation of modified silica;

[0057] The modified liquid and silicon dioxide were ground and mixed at a grinding temperature of 25°C for 6 minutes, and the mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to silicon dioxide was 1:1;

[0058] Heat treatment is performed until the soy protein isolate is denatured, the heat treatment adopts steam treatment, and the heat treatment time is 70 minutes;

[0059] Freeze drying to obtain modified silica, the freeze drying process is: first freeze at -70°C for 48 hours, then keep the temperature constant and freeze dry at a vacuum degree of 2Pa for 48 hours;

[0060] (4) Preparation of modified silica loaded with curcumin;

[0061] The modified silicon dioxide is immersed in an ethanol solution of curcumin and then dried to obtain a modified silicon dioxide loaded with curcumin, wherein the concentration of the ethanol solution of curcumin is 1wt%, the mass ratio of the modified silicon dioxide to the ethanol solution of curcumin is 1:40, the immersion temperature is 40°C, the immersion time is 10min, and the drying is carried out by vacuum drying at a temperature of 60°C and a drying time of 24h;

[0062] (5) Preparation of PA6 fluorescent powder;

[0063] The modified silica loaded with curcumin, PA6 and water are mixed, the mass ratio of the modified silica loaded with curcumin, PA6 and water is 0.3:1.3:60, then the temperature is raised to 162°C and kept for 26 hours, then the temperature is lowered to 25°C and cooled, and finally vacuum dried at 60°C for 24 hours to obtain PA6 fluorescent powder.

[0064] The yield of the final PA6 fluorescent powder is 70%; the average particle size is 90μm. Figure 2 As shown; the encapsulation rate of curcumin is 92% and the loading rate is 5.4%.

[0065] Comparative Example 1

[0066] A method for preparing PA6 composite powder is basically the same as that of Example 1, except that: in step (3), heat treatment is omitted.

[0067] The curcumin embedding efficiency of the prepared PA6 composite powder was 31%, and the loading rate was 1.6%.

[0068] Compared with Example 1, the embedding rate and loading rate of curcumin are significantly reduced. This is because Example 1 of the present invention uses protein denaturation to form a "sheath" with soy protein isolate and then tightly fixes silica therein. Since soy protein isolate is an excellent carrier of curcumin, it can adsorb and bind curcumin, thereby obtaining modified silica uniformly loaded with curcumin, thereby improving the embedding rate and loading rate of curcumin in PA6 fluorescent powder. After grinding the protein and silica in Comparative Example 1, soy protein isolate cannot form a "sheath" state on the surface of silica. Soy protein isolate only forms an uneven concave-convex state on the surface of silica, and cannot completely wrap silica, which affects the loading of silica on curcumin and reduces the embedding rate and loading rate of curcumin in PA6 composite powder.

[0069] Example 2

[0070] A method for preparing PA6 fluorescent powder, the specific steps are as follows:

[0071] (1) Preparation of raw materials;

[0072] Soy protein isolate: CAS: 9010-10-0, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0073] Corn starch: CAS: 9005-25-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0074] Ethyl acetate;

[0075] Disodium hydrogen phosphate;

[0076] PVP: CAS: 9003-39-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0077] water;

[0078] Silicon dioxide: average particle size 50 nm, CAS: 7631-86-9, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0079] Curcumin: CAS: 458-37-7, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0080] Ethanol;

[0081] PA6;

[0082] (2) Preparation of modified liquid;

[0083] Soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP were mixed in water and stirred at 55°C for 1.5 hours to obtain a modified solution, wherein the mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP was 5:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP in the modified solution was 80wt%;

[0084] (3) Preparation of modified silica;

[0085] The modified liquid and silicon dioxide were ground and mixed, the grinding temperature was 20°C, the grinding time was 5 min, and the mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to silicon dioxide was 1:1;

[0086] Heat treatment is performed until the soy protein isolate is denatured, the heat treatment adopts steam treatment, and the heat treatment time is 60 minutes;

[0087] Freeze drying to obtain modified silica, the freeze drying process is: first freeze at -70°C for 50 hours, then keep the temperature constant and freeze dry at a vacuum degree of 2.5 Pa for 50 hours;

[0088] (4) Preparation of modified silica loaded with curcumin;

[0089] The modified silicon dioxide is immersed in an ethanol solution of curcumin and then dried to obtain a modified silicon dioxide loaded with curcumin; wherein the concentration of the ethanol solution of curcumin is 0.5wt%, the mass ratio of the modified silicon dioxide to the ethanol solution of curcumin is 1:50, the immersion temperature is 30°C, the immersion time is 5min, and the drying is carried out by vacuum drying at a temperature of 60°C and a drying time of 24h;

[0090] (5) Preparation of PA6 fluorescent powder;

[0091] The modified silica loaded with curcumin, PA6 and water are mixed, the mass ratio of the modified silica loaded with curcumin, PA6 and water is 0.2:1.3:50, then the temperature is raised to 160°C and kept for 24 hours, then the temperature is lowered to 20°C and cooled, and finally vacuum dried at 60°C for 24 hours to obtain PA6 fluorescent powder.

[0092] The final yield of the PA6 fluorescent powder was 70%, the average particle size was 100 μm, the encapsulation rate of curcumin was 85%, and the loading rate was 4.9%.

[0093] Example 3

[0094] A method for preparing PA6 fluorescent powder, the specific steps are as follows:

[0095] (1) Preparation of raw materials;

[0096] Soy protein isolate: CAS: 9010-10-0, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0097] Corn starch: CAS: 9005-25-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0098] Ethyl acetate;

[0099] Disodium hydrogen phosphate;

[0100] PVP: CAS: 9003-39-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0101] water;

[0102] Silicon dioxide: average particle size 50 nm, CAS: 7631-86-9, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0103] Curcumin: CAS: 458-37-7, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0104] Ethanol;

[0105] PA6;

[0106] (2) Preparation of modified liquid;

[0107] Soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP were mixed in water and stirred at 58°C for 1.7 hours to obtain a modified solution, wherein the mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP was 5.2:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP in the modified solution was 81wt%;

[0108] (3) Preparation of modified silica;

[0109] The modified liquid and silicon dioxide were ground and mixed, the grinding temperature was 22°C, the grinding time was 5.5 min, and the mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to silicon dioxide was 1:1;

[0110] Heat treatment is performed until the soy protein isolate is denatured, the heat treatment adopts steam treatment, and the heat treatment time is 65 minutes;

[0111] Freeze drying to obtain modified silica, the freeze drying process is: first freeze at -70°C for 49 hours, then keep the temperature constant and freeze dry at a vacuum degree of 2.2 Pa for 49 hours;

[0112] (4) Preparation of modified silica loaded with curcumin;

[0113] The modified silicon dioxide is immersed in an ethanol solution of curcumin and then dried to obtain a modified silicon dioxide loaded with curcumin; wherein the concentration of the ethanol solution of curcumin is 0.75wt%, the mass ratio of the modified silicon dioxide to the ethanol solution of curcumin is 1:45, the immersion temperature is 35°C, the immersion time is 7min, and the drying is carried out by vacuum drying at a temperature of 60°C for 24h;

[0114] (5) Preparation of PA6 fluorescent powder;

[0115] The modified silica loaded with curcumin, PA6 and water are mixed, the mass ratio of the modified silica loaded with curcumin, PA6 and water is 0.25:1.3:55, then the temperature is raised to 161°C and kept for 25 hours, then the temperature is lowered to 22°C and cooled, and finally vacuum dried at 60°C for 24 hours to obtain PA6 fluorescent powder.

[0116] The final yield of PA6 fluorescent powder was 70%, the average particle size was 95 μm, the encapsulation rate of curcumin was 88%, and the loading rate was 5.2%.

[0117] Example 4

[0118] A method for preparing PA6 fluorescent powder, the specific steps are as follows:

[0119] (1) Preparation of raw materials;

[0120] Soy protein isolate: CAS: 9010-10-0, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0121] Corn starch: CAS: 9005-25-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0122] Ethyl acetate;

[0123] Disodium hydrogen phosphate;

[0124] PVP: CAS: 9003-39-8, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0125] water;

[0126] Silicon dioxide: average particle size 50 nm, CAS: 7631-86-9, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0127] Curcumin: CAS: 458-37-7, provided by Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0128] Ethanol;

[0129] PA6;

[0130] (2) Preparation of modified liquid;

[0131] Soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP were mixed in water and stirred at 60°C for 2 hours to obtain a modified solution, wherein the mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP was 5.5:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP in the modified solution was 82wt%;

[0132] (3) Preparation of modified silica;

[0133] The modified liquid and silicon dioxide were ground and mixed at a grinding temperature of 25°C for 6 minutes, and the mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to the mass ratio of silicon dioxide was 1:1;

[0134] Heat treatment is performed until the soy protein isolate is denatured, the heat treatment adopts steam treatment, and the heat treatment time is 70 minutes;

[0135] Freeze drying to obtain modified silica, the freeze drying process is: first freeze at -70°C for 48 hours, then keep the temperature constant and freeze dry at a vacuum degree of 2Pa for 48 hours;

[0136] (4) Preparation of modified silica loaded with curcumin;

[0137] The modified silicon dioxide is immersed in an ethanol solution of curcumin and then dried to obtain a modified silicon dioxide loaded with curcumin, wherein the concentration of the ethanol solution of curcumin is 1wt%, the mass ratio of the modified silicon dioxide to the ethanol solution of curcumin is 1:50, the immersion temperature is 40°C, the immersion time is 10min, and the drying is carried out by vacuum drying at a temperature of 60°C and a drying time of 24h;

[0138] (5) Preparation of PA6 fluorescent powder;

[0139] The modified silica loaded with curcumin, PA6 and water are mixed, the mass ratio of the modified silica loaded with curcumin, PA6 and water is 0.3:1.3:50, then the temperature is raised to 162°C and kept for 26 hours, then the temperature is lowered to 25°C and cooled, and finally vacuum dried at 60°C for 24 hours to obtain PA6 fluorescent powder.

[0140] The final yield of PA6 fluorescent powder was 70%, the average particle size was 94 μm, the encapsulation rate of curcumin was 90%, and the loading rate was 5.2%.

[0141] Example 5

[0142] A method for preparing PA6 fluorescent powder is basically the same as Example 4, except that: in step (1), disodium hydrogen phosphate and PVP are not prepared, and in step (2), disodium hydrogen phosphate and PVP are not added when preparing the modified liquid.

[0143] The final yield of PA6 fluorescent powder was 70%, the average particle size was 86 μm, the encapsulation rate of curcumin was 68%, and the loading rate was 1.6%.

[0144] By comparing Example 4 with Example 5, it can be seen that the curcumin embedding rate of the PA6 fluorescent powder of Example 5 is significantly lower than that of Example 4. This is because Example 4 further introduces disodium hydrogen phosphate and PVP in the process of forming the "shell" relative to Example 5, which can improve the water retention performance of corn starch. The better the water retention performance of corn starch, the more conducive it is to forming pores and adsorbing curcumin.

[0145] Comparative Example 2

[0146] A method for preparing PA6 fluorescent powder is basically the same as that of Example 5, except that corn starch and ethyl acetate are not prepared in step (1), and corn starch and ethyl acetate are not added when preparing the modified liquid in step (2).

[0147] The final yield of PA6 fluorescent powder was 70%, the average particle size was 64 μm, the encapsulation rate of curcumin was 0.2%, and the loading rate was 0.3%.

[0148] By comparing Example 5 with Comparative Example 2, it can be seen that the embedding rate of curcumin in the PA6 fluorescent powder of Comparative Example 2 is significantly lower than that of Example 5. This is because corn starch and ethyl acetate are also introduced into Example 5 in the process of forming the "shell" relative to Comparative Example 2. Corn starch has high water absorption and can absorb a large amount of water. A large number of pores can be formed after freeze-drying, thereby enhancing the adsorption of curcumin.

Claims

1. A method for preparing PA6 fluorescent powder, characterized in that: The modified liquid containing soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, PVP and water is ground and mixed with silica, and then heat-treated to denature the soy protein isolate, and then freeze-dried to obtain modified silica, and then the modified silica is used to load curcumin, and finally the modified silica loaded with curcumin and PA6 are compounded in a solvent by a dissolution precipitation method to obtain PA6 fluorescent powder; The preparation process of the modified liquid is as follows: after mixing soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate and PVP in water, stirring at 55-60° C. for 1.5-2 hours; The heat treatment adopts steam treatment, and the heat treatment time is 60 to 70 minutes; Using modified silica to load curcumin means: immersing the modified silica in an ethanol solution of curcumin and then drying, wherein the concentration of the ethanol solution of curcumin is 0.5-1wt%, the mass ratio of the modified silica to the ethanol solution of curcumin is 1:40-50, the immersion temperature is 30-40°C, and the immersion time is 5-10min; Compounding the modified silica loaded with curcumin and PA6 in a solvent by a dissolution precipitation method means: after mixing the modified silica loaded with curcumin, PA6 and water, heating to 160-162° C. and keeping the temperature for 24-26 hours, cooling to 20-25° C., and then post-treating, wherein the mass ratio of the modified silica loaded with curcumin, PA6 and water is 0.2-0.3:1.3:50-60.

2. The method for preparing PA6 fluorescent powder according to claim 1, characterized in that: The mass ratio of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate and PVP is 5-5.5:1:0.1:0.2:0.2, and the total concentration of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate and PVP in the modified liquid is 80-82wt%.

3. The method for preparing PA6 fluorescent powder according to claim 2, characterized in that: The mass ratio of the total mass of soy protein isolate, corn starch, ethyl acetate, disodium hydrogen phosphate, and PVP to silicon dioxide is 1:

1.

4. The method for preparing a PA6 fluorescent powder according to claim 1, characterized in that: The grinding temperature is 20-25°C and the grinding time is 5-6 minutes.

5. The method for preparing PA6 fluorescent powder according to claim 1, characterized in that: The freeze drying process is: First freeze at -70℃ for 48 to 50 hours, then keep the temperature constant and freeze at a vacuum degree of 2 to 2.5Pa for 48 to 50 hours.

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