Cool polylactic acid composite material, preparation method and application thereof, and cool polylactic acid fiber

Abstract

The invention discloses a cool polylactic acid composite material, a preparation method and application thereof and a cool polylactic acid fiber, and relates to the technical field of cool fibers, the preparation method of the cool polylactic acid composite material comprises the following steps: (1) under the action of an initiator, polylactic acid reacts with maleic anhydride to obtain maleic anhydride grafted polylactic acid; and (2) carrying out melt blending on the maleic anhydride grafted polylactic acid and the cool feeling agent, and carrying out cooling granulation to obtain the cool feeling polylactic acid composite material. The prepared cool-feeling fiber has natural cool-feeling performance, the hydrophilicity of polylactic acid and the compatibility of polylactic acid and jade powder are effectively improved through the chemical reaction of polylactic acid and maleic anhydride, the cool-feeling effect of the fiber is enhanced through jade powder, and the problem that traditional polylactic acid fiber is poor in comfort in a high-temperature environment is solved.

Description

Technical Field

[0001] This invention relates to the field of cooling fiber technology, specifically to a cooling polylactic acid composite material, its preparation method and application, and cooling polylactic acid fiber. Background Technology

[0002] Polylactic acid (PLA) fiber has been widely used in textiles, packaging, and medicine due to its biodegradability, environmental friendliness, and good physical properties. However, traditional PLA fibers typically perform poorly in high-temperature environments and lack comfortable cooling properties, which limits their application in summer clothing, sportswear, and other fields. To improve the cooling properties of PLA fibers, researchers have explored various methods to enhance their thermal properties.

[0003] Currently, one common technique to improve the cooling properties of PLA fibers is to introduce hydrophilic groups into their molecular structure. However, this method often leads to a decrease in the mechanical properties and durability of PLA, and the improvement in hydrophilicity is limited. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a cooling polylactic acid composite material, its preparation method and its application in cooling fibers. Maleic anhydride is used to graft and modify PLA, which effectively improves the hydrophilicity, processability and compatibility with inorganic powders of PLA. The introduction of cooling particles can give the fiber an additional cooling effect and increase the comfort when wearing it.

[0005] The technical problem to be solved by this invention is achieved by the following technical solution:

[0006] The first objective of this invention is to provide a method for preparing a cooling polylactic acid composite material, comprising the following steps:

[0007] (1) Under the action of an initiator, polylactic acid reacts with maleic anhydride to obtain maleic anhydride-grafted polylactic acid.

[0008] (2) Maleic anhydride-grafted polylactic acid and a cooling agent are melt-blended, cooled and granulated to obtain a cooling polylactic acid composite material.

[0009] A second objective of this invention is to provide a cool-feeling polylactic acid composite material obtained by the aforementioned preparation method.

[0010] A third objective of this invention is to provide the application of the aforementioned cooling polylactic acid composite material in cooling fibers.

[0011] The fourth objective of this invention is to provide a cooling polylactic acid fiber, which is obtained by melting and spinning the aforementioned cooling polylactic acid composite material with polylactic acid, and then stretching it.

[0012] The beneficial effects of this invention are:

[0013] 1. This invention significantly improves the cooling properties of PLA fibers by combining maleic anhydride-grafted polylactic acid with cooling particles, while maintaining their original excellent mechanical properties and environmental characteristics. This provides a new technical route and a broader market prospect for the application of PLA fibers in high-temperature environments.

[0014] 2. The cooling fiber prepared by this invention has natural cooling properties. The chemical reaction between polylactic acid and maleic anhydride effectively improves the hydrophilicity of polylactic acid and its compatibility with jade powder. Furthermore, the jade powder enhances the cooling effect of the fiber, thus solving the problem of poor comfort of traditional polylactic acid fibers in high-temperature environments.

[0015] 3. By introducing maleic anhydride, this invention improves the chemical structure of polylactic acid, enabling polylactic acid to better combine with cooling particles, further enhancing the cooling effect of the fiber, while maintaining the biodegradability and environmental performance of polylactic acid.

[0016] 4. This invention achieves uniform dispersion of cooling particles within a polylactic acid matrix through melt blending, and further disperses these particles evenly on the surface and interior of the fiber through melt spinning. Simultaneously, the continuous grooves on the fiber surface give the fiber excellent thermal conductivity, allowing for rapid heat dissipation from the body. The cooling fiber prepared by this invention utilizes its high thermal conductivity to generate a cooling sensation when the skin comes into contact with the fabric, providing the wearer with a cool and comfortable experience.

[0017] 5. This invention solves the technical problem of combining traditional polylactic acid (PLA) fibers with cooling particles, provides an efficient and environmentally friendly method for preparing PLA composite materials, and applies this PLA composite material to the processing of cooling fibers, thus broadening the application range of PLA fibers in cooling materials and further improving the functionality and market competitiveness of PLA fibers. Attached Figure Description

[0018] Figure 1 Fourier transform infrared (FTIR) spectra of maleic anhydride-grafted PLA prepared in Example 1 and pure PLA. Detailed Implementation

[0019] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.

[0020] This invention provides a method for preparing a cooling polylactic acid composite material, comprising the following steps:

[0021] (1) Under the action of an initiator, polylactic acid reacts with maleic anhydride to obtain maleic anhydride-grafted polylactic acid.

[0022] (2) Maleic anhydride-grafted polylactic acid and a cooling agent are melt-blended, cooled and granulated to obtain a cooling polylactic acid composite material.

[0023] Furthermore, the polylactic acid undergoes a drying pretreatment before use. Preferably, the drying is vacuum drying at a temperature of 50–80°C for 12–24 hours. Vacuum drying removes moisture from the polylactic acid.

[0024] Furthermore, the initiator includes, but is not limited to, at least one of dicumyl peroxide, benzoyl peroxide, and azobisisobutyronitrile.

[0025] Further, the mass ratio of polylactic acid, maleic anhydride, and initiator is 100:(5-10):(0.1-0.5). Under the action of the initiator, maleic anhydride is grafted onto the polylactic acid molecular chain.

[0026] Furthermore, the reaction temperature of the polylactic acid and maleic anhydride is 170–190°C, and the reaction time is 5–15 min. After the reaction, the product maleic anhydride-grafted polylactic acid is purified by a dissolution-precipitation method. Dichloromethane is preferred as the dissolution agent, ethanol is preferred as the precipitant, and the purification is preferably performed three times.

[0027] Furthermore, the maleic anhydride-grafted polylactic acid and cooling agent undergo a drying pretreatment before use. Preferably, the drying is vacuum drying at a temperature of 80–100°C for 8–12 hours. Vacuum drying removes moisture from the maleic anhydride-grafted polylactic acid and cooling agent.

[0028] Furthermore, the cooling agent is jade powder. Preferably, the particle size of the jade powder is less than 0.1 mm. Jade powder is a crystalline powder processed from natural jade, mainly composed of silicon dioxide and magnesium oxide, and possesses antibacterial, antifungal, and environmentally friendly properties. This invention uses jade powder as a cooling agent, which is not only widely available but also has good skin affinity.

[0029] Furthermore, the mass ratio of maleic anhydride-grafted polylactic acid to the cooling agent is 100:(5-10).

[0030] Furthermore, the melt blending temperature is 170–190°C. Melt blending allows the cooling agent to be uniformly dispersed in maleic anhydride-grafted polylactic acid.

[0031] PLA molecules are nonpolar, while jade powder is rich in hydroxyl groups on its surface. Direct blending of the two can easily lead to agglomeration due to high interfacial tension. After grafting PLA with MAH (PLA-g-MAH), the anhydride / carboxyl groups introduced into the molecular chain can form hydrogen or ester bonds with the hydroxyl groups on the jade powder surface, reducing interfacial energy. In terms of mechanical properties, when unmodified PLA is blended with jade powder, the rigid particles can restrict molecular chain movement, increasing fiber brittleness. The cooling sensation of jade powder stems from its high thermal conductivity and heat capacity, allowing it to quickly absorb and conduct heat from the body. However, due to poor compatibility, unmodified PLA and jade powder are prone to interfacial gaps and particle agglomeration, interrupting heat transfer pathways and diminishing the cooling effect.

[0032] The present invention provides a cool-feeling polylactic acid composite material obtained by the aforementioned preparation method.

[0033] This invention provides the application of the aforementioned cooling polylactic acid composite material in cooling fibers. The cooling polylactic acid composite material prepared according to this invention can be used as a masterbatch for the processing of cooling polylactic acid fibers, or it can be combined with other polymers for the processing of cooling fibers.

[0034] The present invention also provides a cooling polylactic acid fiber, which is obtained by mixing the aforementioned cooling polylactic acid composite material with polylactic acid, then melt spinning and stretching.

[0035] Furthermore, the mass ratio of the polylactic acid to the cooling polylactic acid composite material is 100:(5-10).

[0036] Furthermore, the melt spinning temperature is 180–200°C. Maleic anhydride-grafted polylactic acid is heated and melted through melt spinning, with a cooling agent dispersed within it. After spinning and forming, the resulting fibers are cooled and solidified to obtain cooling polylactic acid fibers.

[0037] Furthermore, the stretching speed is 100–500 m / min. Stretching allows the melt stream to undergo irreversible plastic deformation before cooling, promoting the axial orientation of polymer chains and forming submicron to micron-scale fiber structures.

[0038] Example 1

[0039] (1) Place PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0040] (2) The PLA dried in step (1) was added to a reaction vessel with maleic anhydride and dicumyl peroxide in a mass ratio of 100:8:0.5. The mixture was stirred for 8 minutes at 180°C and 1000 rpm. After the reaction was completed, the product was added to dichloromethane and heated to 60°C until completely dissolved. The product was then precipitated with ethanol. The dissolution-precipitation operation was repeated three times. The precipitate was dried in a vacuum drying oven at 60°C for 12 hours to obtain maleic anhydride-grafted PLA.

[0041] (3) The maleic anhydride-grafted PLA and jade powder prepared in step (2) were placed in a vacuum drying oven at 100℃ and dried for 10 hours for later use.

[0042] (4) The maleic anhydride-grafted PLA and jade powder dried in step (3) are added to a twin-screw extruder at a mass ratio of 100:5, melt-extruded at 180°C, cooled in a water bath, and cut into granules to obtain cool-feel PLA masterbatch.

[0043] (5) Place the cooling PLA masterbatch and PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0044] (6) The cool-feeling PLA masterbatch dried in step (5) and PLA are mixed evenly in a mass ratio of 5:100 and then melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain cool-feeling PLA fiber.

[0045] Figure 1 The FTIR spectra of maleic anhydride-grafted PLA prepared in Example 1 and pure PLA are shown. Figure 1 It can be seen that the molecular structure of PLA changes after maleic anhydride grafting modification. The FTIR spectra of pure PLA and maleic anhydride-grafted PLA show significant differences, especially at 1862 cm⁻¹. -1 The absorption peak observed in the FTIR spectrum of maleic anhydride-grafted PLA appeared at the specified peak, while it was not present in the FTIR spectrum of pure PLA. This indicates that the maleic anhydride molecule successfully underwent a grafting reaction with PLA. The acyl group of maleic anhydride bonded to the PLA molecular chain through a chemical reaction, forming a new chemical bond. Therefore, the appearance of this absorption peak confirms the success of the maleic anhydride grafting modification.

[0046] Example 2

[0047] The method is the same as in Example 1, except that the mass ratio of maleic anhydride-grafted PLA to jade powder in step (4) is adjusted to 100:7.

[0048] (1) Place PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0049] (2) The PLA dried in step (1) was added to a reaction vessel with maleic anhydride and dicumyl peroxide in a mass ratio of 100:8:0.5. The mixture was stirred for 8 minutes at 180°C and 1000 rpm. After the reaction was completed, the product was added to dichloromethane and heated to 60°C until completely dissolved. The product was then precipitated with ethanol. The dissolution-precipitation operation was repeated three times. The precipitate was dried in a vacuum drying oven at 60°C for 12 hours to obtain maleic anhydride-grafted PLA.

[0050] (3) The maleic anhydride-grafted PLA and jade powder prepared in step (2) were placed in a vacuum drying oven at 100℃ and dried for 10 hours for later use.

[0051] (4) The maleic anhydride-grafted PLA and jade powder dried in step (3) are added to a twin-screw extruder at a mass ratio of 100:7, melt-extruded at 180°C, cooled in a water bath, and cut into granules to obtain cool-feel PLA masterbatch.

[0052] (5) Place the cooling PLA masterbatch and PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0053] (6) The cool-feeling PLA masterbatch dried in step (5) and PLA are mixed evenly in a mass ratio of 5:100 and then melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain cool-feeling PLA fiber.

[0054] Example 3

[0055] The method is the same as in Example 1, except that the mass ratio of PLA to dicumyl peroxide in step (2) is adjusted to 100:0.3.

[0056] (1) Place PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0057] (2) The PLA dried in step (1) was added to a reaction vessel with maleic anhydride and dicumyl peroxide in a mass ratio of 100:8:0.3. The mixture was stirred for 8 minutes at 180°C and 1000 rpm. After the reaction was completed, the product was added to dichloromethane and heated to 60°C until completely dissolved. The product was then precipitated with ethanol. The dissolution-precipitation operation was repeated three times. The precipitate was dried in a vacuum drying oven at 60°C for 12 hours to obtain maleic anhydride-grafted PLA.

[0058] (3) The maleic anhydride-grafted PLA and jade powder prepared in step (2) were placed in a vacuum drying oven at 100℃ and dried for 10 hours for later use.

[0059] (4) The maleic anhydride-grafted PLA and jade powder dried in step (3) are added to a twin-screw extruder at a mass ratio of 100:5, melt-extruded at 180°C, cooled in a water bath, and cut into granules to obtain cool-feel PLA masterbatch.

[0060] (5) Place the cooling PLA masterbatch and PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0061] (6) The cool-feeling PLA masterbatch dried in step (5) and PLA are mixed evenly in a mass ratio of 5:100 and then melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain cool-feeling PLA fiber.

[0062] Example 4

[0063] The method is the same as in Example 1, except that the mass ratio of cooling PLA masterbatch to PLA in step (6) is adjusted to 8:100.

[0064] (1) Place PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0065] (2) The PLA dried in step (1) was added to a reaction vessel with maleic anhydride and dicumyl peroxide in a mass ratio of 100:8:0.5. The mixture was stirred for 8 minutes at 180°C and 1000 rpm. After the reaction was completed, the product was added to dichloromethane and heated to 60°C until completely dissolved. The product was then precipitated with ethanol. The dissolution-precipitation operation was repeated three times. The precipitate was dried in a vacuum drying oven at 60°C for 12 hours to obtain maleic anhydride-grafted PLA.

[0066] (3) The maleic anhydride-grafted PLA and jade powder prepared in step (2) were placed in a vacuum drying oven at 100℃ and dried for 10 hours for later use.

[0067] (4) The maleic anhydride-grafted PLA and jade powder dried in step (3) are added to a twin-screw extruder at a mass ratio of 100:5, melt-extruded at 180°C, cooled in a water bath, and cut into granules to obtain cool-feel PLA masterbatch.

[0068] (5) Place the cooling PLA masterbatch and PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0069] (6) The cool-feeling PLA masterbatch dried in step (5) and PLA are mixed evenly in a mass ratio of 8:100 and then melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain cool-feeling PLA fiber.

[0070] Comparative Example 1

[0071] The method is the same as in Example 1, except that maleic anhydride was not used to graft PLA.

[0072] (1) Place PLA and jade powder in a vacuum drying oven at 100℃ and dry for 10 hours, then set aside.

[0073] (2) The PLA and jade powder dried in step (1) are added to a twin-screw extruder at a mass ratio of 100:5, melt-extruded at 180°C, cooled in a water bath, and cut into granules to obtain cool-feel PLA masterbatch.

[0074] (3) Place the cooling PLA masterbatch and PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0075] (4) The cool-feeling PLA masterbatch dried in step (3) and PLA are mixed evenly in a mass ratio of 5:100 and then melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain cool-feeling PLA fiber.

[0076] Comparative Example 2

[0077] The method is the same as in Example 1, except that PLA fibers are prepared directly from pure PLA.

[0078] (1) Place PLA in a vacuum drying oven at 60℃ and dry for 12 hours for later use.

[0079] (2) The PLA dried in step (1) is melt-spun and drawn. The spinning temperature is 180℃ and the drawing speed is 300r / min to obtain PLA fibers.

[0080] The contact cooling coefficient of the cooling PLA fibers prepared in Examples 1-4 and Comparative Example 1, as well as the PLA fiber prepared in Comparative Example 2, was tested, and the results are shown in Table 1.

[0081] Table 1

[0082] sample <![CDATA[Cool touch coefficient (q max ) / J·cm -2 ·s -1 > Cooling PLA fiber prepared in Example 1 0.227 Cooling PLA fiber prepared in Example 2 0.316 Cooling PLA fiber prepared in Example 3 0.285 Cooling PLA fiber prepared in Example 4 0.290 Cooling PLA fibers prepared in Comparative Example 1 0.096 PLA fibers prepared in Comparative Example 2 0.135

[0083] As shown in Table 1, the cooling PLA fiber prepared by this invention exhibits significant cooling properties. Cooling properties refer to the fiber's ability to transfer heat when in contact with the skin, and are closely related to the fiber's hydrophilicity, surface structure, and hygroscopic properties. Grafting maleic anhydride improves the hydrophilicity of PLA, enhancing its heat conduction efficiency when in contact with the skin, thus resulting in a better cooling effect.

[0084] The tensile properties of the cooling PLA fibers prepared in Examples 1-4 and Comparative Example 1, as well as the PLA fibers prepared in Comparative Example 2, were tested, and the results are shown in Table 2.

[0085] Table 2

[0086]

[0087]

[0088] As shown in Table 2, adding jade powder and grafting PLA with maleic anhydride can make the prepared cool-feeling PLA fiber have higher tensile strength, which can withstand stronger tension and friction in daily use, and is less prone to breakage, deformation and other problems, thus greatly extending its service life.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a cool-feeling polylactic acid composite material, characterized by, The method comprises the following steps: (1) reacting polylactic acid with maleic anhydride under the action of an initiator to obtain maleic anhydride grafted polylactic acid; (2) melt blending the maleic anhydride grafted polylactic acid with a cooling agent, cooling and granulating to obtain a cooling polylactic acid composite material.

2. The method of claim 1, wherein: The initiator is at least one of dicumyl peroxide, benzoyl peroxide and azobisisobutyronitrile.

3. The method of claim 1, wherein: The mass ratio of the polylactic acid, the maleic anhydride and the initiator is 100:(5-10):(0.1-0.5).

4. The method of claim 1, wherein: The reaction temperature of the polylactic acid and the maleic anhydride is 170-190°C, and the reaction time is 5-15 min.

5. The method of claim 1, wherein: The cooling agent is jade powder. Preferably, the mass ratio of the maleic anhydride grafted polylactic acid and the cooling agent is 100:(5-7).

6. The method of claim 1, wherein: The temperature of the melt blending is 170-190°C.

7. A cooling polylactic acid composite material obtained by the preparation method in any one of claims 1-6.

8. Use of the cooling polylactic acid composite material in claim 7 in a cooling fiber.

9. A cool-feeling polylactic acid fiber, characterized by: Mixing the cooling polylactic acid composite material in claim 7 with polylactic acid, melt spinning, and drawing to obtain a cooling polylactic acid fiber.

10. The cool polylactic acid fiber according to claim 9, wherein: The temperature of the melt spinning is 180-200°C. Preferably, the drawing speed is 100-500 m / min.

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