Recycled cotton fiber modified polypropylene composite material with fresh scent and soft touch feeling and preparation method of recycled cotton fiber modified polypropylene composite material

Abstract

The invention discloses a recycled cotton fiber modified polypropylene composite material with fresh scent and soft touch feeling and a preparation method thereof. The polypropylene composite material is prepared from the following raw materials in percentage by weight: 40 to 60 parts of polypropylene, 20 to 30 parts of elastomer, 10 to 15 parts of whisker, 2 to 8 parts of processing aid and 5 to 10 parts of cyclodextrin modified cotton fiber. The cyclodextrin modified cotton fiber fragrant master batch is prepared from the following raw materials in percentage by weight: 80 to 90 parts of recycled cotton fiber, 10 to 20 parts of beta-cyclodextrin, 2 to 5 parts of liquid essence, 2 to 4 parts of cross-linking agent and 1 to 2 parts of catalyst. By modifying the recycled cotton fibers with beta-cyclodextrin including essence, the method not only solves the problem of dispersion of the recycled cotton fibers in a resin base material, but also optimizes the problem of poor odor of the recycled cotton fibers.

Description

Technical Field

[0001] This invention relates to a recycled cotton fiber modified polypropylene composite material with a pleasant aroma and soft texture, and its preparation method. The resulting material has special flavor, good texture, and environmentally friendly properties, and belongs to the field of polymer material processing and modification technology. Background Technology

[0002] Against the backdrop of the automotive industry's shift towards green environmental protection and high-end experiences, developing interior materials that combine sustainability and high quality has become a core issue for the industry. Polypropylene (PP) is widely used in automotive interiors due to its cost and performance advantages, but it has a stiff feel and is prone to producing unpleasant odors during processing and use. Meanwhile, waste cotton fibers generated by the textile industry are a resource-rich renewable material with a porous structure and a natural skin-friendly feel, making them ideal functional fillers. However, using them in modified PP materials still faces many technical bottlenecks.

[0003] In the existing technology, many patents have focused on optimizing the odor and feel of modified PP materials. For example, patent CN107903490A, "A soft-touch modified material with low volatile organic compounds and low odor and its preparation method," improves the feel by adding silicone and ethylene-octene copolymer and reduces odor using a vacuum devolatilization process. However, this method has limited applicability to recycled materials and cannot optimize the flavor of the composite material. Another patent, CN119490712A, "A recycled polypropylene composite material and its preparation method and application," uses nanoporous silicate as an adsorbent to reduce the odor of recycled PP, but this patent focuses on the physical adsorption and control of leaching of raw material odor and does not make any changes to improve the material's texture, especially the optimization of the feel.

[0004] Regarding the utilization of waste fibers, patent CN115122529A provides a technology and process for the recycling, modification, and high-value reuse of polypropylene fiber cloth. However, its technical approach mainly focuses on the recycling process itself, without optimizing the material's odor or texture. CN104911728A introduces a method for preparing easily dyeable modified polypropylene fiber blended recycled cotton yarn. In this method, the recycled cotton fiber mainly serves as a reinforcing skeleton, and its compatibility with the PP matrix remains an issue. Furthermore, it similarly neglects the synergistic optimization of odor and feel.

[0005] Therefore, there is an urgent need in this field for an innovative solution that can fundamentally solve the compatibility problem between recycled cotton fibers and PP while maintaining the mechanical properties of the materials, and synergistically endow the composite material with a lasting fresh scent and excellent feel. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a recycled cotton fiber-modified polypropylene composite material with a pleasant aroma and soft touch, and its preparation method. First, whiskers are used to replace traditional inorganic fillers in the resulting material to maintain the overall mechanical properties of conventional modified PP materials. Second, to optimize the odor generated during the processing of recycled cotton and PP materials, a fragrance is first encapsulated with cyclodextrin, and then used to modify the recycled cotton fibers. This improves the compatibility between the recycled cotton fibers and PP while giving the composite material a specific fragrance. Finally, elastomers and cyclodextrins are used to modify the recycled cotton fibers to enhance the tactile feel of the composite material, thereby achieving a soft-touch effect.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A recycled cotton fiber modified polypropylene composite material with a pleasant fragrance and soft touch, made from the following raw materials in parts by weight:

[0009] 40-60 parts of polypropylene

[0010] 20-30 parts of elastomer

[0011] 10-15 parts whiskers

[0012] Processing aids 2-8 parts,

[0013] 5-10 parts of cyclodextrin-modified cotton fiber;

[0014] The cyclodextrin-modified cotton fiber, by weight, is prepared from the following raw materials:

[0015] 80-90 parts of recycled cotton fiber

[0016] 10-20 parts of β-cyclodextrin

[0017] 2-5 parts liquid fragrance

[0018] 2-4 parts of crosslinking agent

[0019] 1-2 parts of catalyst.

[0020] The polypropylene material is one or more of homopolymer polypropylene and copolymer polypropylene, and specifically, the melt flow rate is between 10 and 60 g / 10 min at 230°C and 2.16 kg.

[0021] The elastomer is one or more of ethylene-vinyl acetate binary copolymer, ethylene-propylene binary copolymer, ethylene-butene binary copolymer, ethylene-hexene binary copolymer, ethylene-octene binary copolymer, and ethylene-propylene-diene terpolymer, with a melting temperature below 130°C.

[0022] The whiskers are one or more of basic magnesium sulfate whiskers and basic barium sulfate whiskers, with a length of 20–50 μm and a diameter of 2–5 μm.

[0023] The processing aids are one or a mixture of several of the following: antioxidant 1010, antioxidant 168, antioxidant DSTP, light stabilizers UV5229, 5589, 531, scratch-resistant silicone / amide additives, and compatibilizer polypropylene grafted maleic anhydride.

[0024] The recycled cotton fibers are post-consumer recycled cotton, are off-white in color, have a length of 1.5-5mm, and an aspect ratio of 100-300.

[0025] The β-cyclodextrin has a purity of ≥98.0% (dry basis, HPLC method) and a solubility of approximately 1.85 g / 100 mL in water at 25 °C.

[0026] The liquid flavoring is a highly heat-resistant, oily liquid, including lemon, milk, and coffee flavors, with the main components having a decomposition temperature of 250℃~280℃.

[0027] The crosslinking agent is one of 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA).

[0028] The catalyst is one of sodium hypophosphite (NaH2PO2) and sodium phosphite (Na2HPO3).

[0029] The method for preparing a recycled cotton fiber modified polypropylene composite material with a pleasant fragrance and soft touch includes the following steps:

[0030] (1) Preparation of cyclodextrin-modified cotton fibers

[0031] Step 1: Add β-cyclodextrin to deionized water (mass ratio of β-cyclodextrin to deionized water 1:10) and heat to 60°C. After the β-cyclodextrin is completely dissolved, add liquid flavoring (mass ratio of β-cyclodextrin to liquid flavoring between 3:1 and 5:1) through a constant pressure dropping funnel and stir continuously for 4-6 hours.

[0032] Step two: Dilute the solution prepared in step one with deionized water to obtain a 20% concentration β-cyclodextrin-encapsulated fragrance solution. Maintain the system temperature at 60℃, then add the crosslinking agent, catalyst, and recycled cotton fibers. After the recycled cotton fibers are fully impregnated, remove them and dry them in an 80-90℃ oven to remove surface moisture, then transfer them to a 150℃ oven for 3-5 minutes. At this time, the crosslinking agent undergoes an esterification reaction under the action of the catalyst, and its carboxyl groups form covalent ester bonds with the cotton fibers and the hydroxyl groups of cyclodextrin, thereby grafting cyclodextrin onto the cotton fibers.

[0033] Step 3: Wash the recycled cotton fibers prepared in Step 2 with deionized water, then freeze-dry them at low temperature and collect the product to obtain cyclodextrin-modified cotton fibers containing fragrance.

[0034] (2) Preparation of recycled cotton fiber modified polypropylene composite material

[0035] Step 1: Mix and stir the polypropylene, elastomer and processing aid package until homogeneous to obtain mixture A;

[0036] Step 2: Mix the whiskers and cyclodextrin-modified cotton fibers evenly to obtain mixture B;

[0037] Step 3: After setting the processing technology, add mixture A from the main feed port of the twin-screw extruder and mixture B from the side feed port (the side feed port should be placed after the melting section and before the mixing section of the twin-screw extruder). Then melt-blend, cool, granulate, and dry to obtain recycled cotton fiber modified polypropylene composite material.

[0038] The processing technology for a recycled cotton fiber modified polypropylene composite material with a pleasant aroma and soft touch involves setting the processing temperatures of zones I to X of a twin-screw extruder sequentially to 135℃, 185℃, 185℃, 195℃, 195℃, 205℃, 220℃, 225℃, 225℃, and 215℃. The main screw speed is 300–450 r / min, the water bath temperature is 23℃–50℃, and the melt temperature should be controlled below 230℃.

[0039] The advantages of this invention are:

[0040] 1. The method of encapsulating liquid fragrance with cyclodextrin solves the problem of difficulty in adding liquid fragrance during processing and optimizes the shortcomings of traditional fragrance materials, such as short fragrance duration and easy fragrance precipitation.

[0041] 2. By modifying recycled cotton fibers with cyclodextrin containing fragrance, the compatibility between recycled cotton fibers and PP is improved, and the composite material is given a unique fragrance.

[0042] 3. Compared with other technological inventions, the technical requirements of this solution are easy to achieve, the loss during the processing is low, the compatibility of the main components in the formula is good, and the mechanical properties are at the same level as those of traditional modified PP materials. Detailed Implementation

[0043] The present invention will be further described in detail below by way of embodiments and comparative examples, but the invention is not limited to the scope of the embodiments described herein.

[0044] Explanation of the main components and proportions in the composite material formulations of the examples and comparative examples:

[0045] Polypropylene A is homopolymer high-crystallinity polypropylene with a melt flow rate of approximately 10 g / 10 min, specifically grade PPBX3500 from SK Chemicals Co., Ltd., South Korea; Polypropylene B is copolymer high-impact polypropylene with a melt flow rate of approximately 10 g / 10 min, specifically grade PP SP179 from Zhenhai Refining & Chemical Co., Ltd.; the elastomer is 8-carbon POE, specifically grade POE 8842 from Dow Chemical Co., Ltd.; the whiskers are basic magnesium sulfate, with a length of 35-50 μm and a diameter of 3-4 μm, specifically grade MOS from Ube Materials Co., Ltd., Japan. HIGE; the processing aids are self-made baseless auxiliary masterbatches, containing antioxidants 168, 1010, and DSTP, as well as compatibilizer PP-g-MAH; the recycled cotton fibers are off-white, 1.5–2 mm in length, and specifically branded as FD-180 from Guangdong Yuanda Textile Co., Ltd.; the cyclodextrin is 99% pure β-cyclodextrin, specifically branded as Yingjietang-HP-β-CD; liquid fragrance A is a fig-flavored liquid fragrance, specifically branded as Huabao Fragrance-BE251034; the crosslinking agent is 1,2,3,4-butanetetracarboxylic acid (BTCA) from Aladdin Reagent (Shanghai) Co., Ltd.; the catalyst is sodium hypophosphite (NaH2PO2) from Aladdin Reagent (Shanghai) Co., Ltd. The weight percentage of the main components in each example and comparative example is shown in Tables 1 and 2.

[0046] Preparation processes of composite materials in examples and comparative examples:

[0047] The specific production and processing methods and the processing temperature of the extruder are described above and will not be repeated here.

[0048] Performance evaluation method:

[0049] Tensile property testing was conducted according to ISO 527-2 standard, with a sample size of 170mm × 10mm × 4mm; bending property testing was conducted according to ISO 178 standard, with a sample size of 80mm × 10mm × 4mm, a bending speed of 2mm / min, and a span of 64mm; notched impact testing of simply supported beams was conducted according to ISO 179-1 standard, with a sample size of 80mm × 10mm × 4mm and a notch depth of one-third of the sample thickness; odor testing was conducted according to Volkswagen PV3900 standard, with test conditions of 50g, 80℃*2h, and the test samples were divided into two states: untreated and dried at 100℃ for 12h. The test results were averaged after testing by 3 people; emission testing was conducted according to VDA278 standard, with the test samples divided into two states: untreated and dried at 100℃ for 8h; the performance test results corresponding to each example and comparative example are shown in Table 3.

[0050] Table 1. Formulation composition (by weight percentage) of cyclodextrin-modified recycled cotton fiber

[0051] Cyclodextrin modified cotton fiber A Cyclodextrin modified cotton fiber B Recycled cotton fibers 83 80 β-Cyclodextrin 10 15 Liquid Fragrance A 3 / Liquid Fragrance A / 2 Crosslinking agent 3 2 catalyst 1 1

[0052] Table 2. Material composition (weight percentage) of Examples 1-6 and Comparative Examples 1-4

[0053]

[0054]

[0055] Table 3. Material property test results of Examples 1-5 and Comparative Examples 1-3

[0056]

[0057] Examples 1 to 4 demonstrate the performance of the material of the present invention by optimizing the relative content of recycled cotton fibers in a PP / elastomer / cyclodextrin modified system. In terms of mechanical properties, it basically meets the performance requirements of automotive interior decorative parts. Regarding odor results, the recycled cotton fibers modified with fragrance-encapsulated cyclodextrin, when added to the material, do not exhibit the foul or rotten smell of recycled materials; instead, they possess a unique fragrance imparted by the fragrance.

[0058] Compared with Examples 1-2, Comparative Examples 1-2 differ primarily in their formulations for cyclodextrin-modified recycled cotton fibers. The fragrance / cyclodextrin ratio in cyclodextrin-modified cotton fiber B was reduced, resulting in minimal change to its mechanical properties. While all cases achieved an odor rating of 3.5 in the odor test, the concentration of the odor odor was significantly lower. Combined with the emission test results, it was found that due to the reduced fragrance / cyclodextrin ratio in cyclodextrin-modified cotton fiber B, both pre- and post-treatment VOC and FOG levels were lower than in Comparative Examples 1-2.

[0059] Combining Examples 1 and Comparative Examples 3 and 5, it can be observed that changing the reinforcing material in the formulation from whiskers + modified recycled cotton fibers to talc or talc + recycled cotton significantly reduces the mechanical properties. This not only demonstrates that whiskers are superior to talc in reinforcing polypropylene resin, but also indicates that modified recycled cotton fibers improve the overall performance of the composite material more effectively than unmodified recycled cotton. Furthermore, combining odor and emission tests, it was found that after baking at 100℃ for 12 hours, the FOG of Example 1 was 91.4% and 26.8% higher than that of Comparative Examples 3 and 5, respectively, while the VOC was higher than that of Comparative Example 3, and the FOG was lower than that of Comparative Example 5. This indicates that the emission of modified recycled cotton fibers is better than that of unmodified recycled cotton, but the overall emission performance is worse than that of talc.

[0060] Combining Example 1 and Comparative Examples 4 and 6, it can be found that when fragrance is added directly to the composite material system without being encapsulated by cyclodextrin, the odor not only fails to reach the level of Example 1, but also the VOC and FOG emissions in the emission test are higher than those in Example 1. In addition, the odor test results of Comparative Example 6 show that without modification of the recycled cotton fibers, their odor cannot be directly masked by fragrance.

Claims

1. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch, characterized in that: The following weight parts of raw materials are used to make the product: ​ polypropylene 40-60 parts, elastomer 20-30 parts, whisker 10-15 parts, processing aid 2-8 parts, cotton fiber modified by cyclodextrin 5-10 parts. The cotton fiber modified by cyclodextrin is prepared from the following raw materials in weight parts: recycled cotton fiber 80-90 parts, β-cyclodextrin 10-20 parts, liquid essence 2-5 parts, crosslinking agent 2-4 parts, catalyst 1-2 parts.

2. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The polypropylene material is one or more of homopolymer polypropylene and copolymer polypropylene, and the melt flow rate of the material is between 10 and 60 g / 10 min at 230℃ and 2.16 Kg.

3. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The elastomer is one or more of ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, and ethylene-propylene-diene terpolymer, and the melting temperature is within 130℃.

4. The recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The whisker is one or more of basic magnesium sulfate whisker and basic barium sulfate whisker, and the length is 20-50 μm and the diameter is 2-5 μm.

5. The recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The processing aid is one or a mixture of several of antioxidant 1010, antioxidant 168, antioxidant DSTP, light stabilizer UV5229, 5589, 531, anti-scratching silicone / amide aid, and compatible agent polypropylene grafted maleic anhydride.

6. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The recycled cotton fiber is post-consumer recycled cotton, and the color is white, the length is 1.5-5 mm, and the length-diameter ratio is 100-300.

7. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The β-cyclodextrin has a purity of ≥98.0% (dry basis, HPLC method) and a solubility in water at 25℃ of about 1.85 g / 100 mL.

8. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The liquid essence is a high-heat-resistant, oily liquid, including lemon, milk, coffee, etc., and the main components have a decomposition temperature of 250-280℃.

9. The recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The crosslinking agent is one of 1,2,3,4-butanetetracarboxylic acid (BTCA) and citric acid (CA).

10. A recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to claim 1, characterized in that: The catalyst is one of sodium hypophosphite (NaH2PO2) and sodium phosphite (Na2HPO3).

11. A method for preparing a recycled cotton fiber modified polypropylene composite material with a fresh scent and soft touch according to any one of claims 1-10, characterized in that: The following steps are included: (1) Preparation of cotton fiber modified by cyclodextrin Step one: β-cyclodextrin is added to deionized water (the mass ratio of β-cyclodextrin to deionized water is 1:10), and the temperature is raised to 60℃. After the β-cyclodextrin is completely dissolved, liquid essence is added through a constant-pressure dropping funnel (the mass ratio of β-cyclodextrin to liquid essence is between 2:1 and 10:1), and stirring is continued. The reaction is carried out for 4-6 hours to obtain solution A. Step two: Solution A is diluted with deionized water to obtain a 20% concentration of β-cyclodextrin inclusion essence solution. The system temperature is maintained at 60℃, and then crosslinking agent, catalyst, and recycled cotton fiber are added. After the recycled cotton fiber is fully soaked, it is taken out and dried in an 80-90℃ oven to remove surface moisture, and then transferred to a 150℃ oven for drying for 3-5 min. At this time, the crosslinking agent undergoes esterification under the action of the catalyst, and the carboxyl groups form covalent ester bonds with the hydroxyl groups of the cotton fiber and the cyclodextrin, thereby grafting the cyclodextrin onto the cotton fiber. Step three, the recycled cotton fiber prepared in step two is washed with deionized water, then low-temperature freeze-drying is carried out and the product is collected to obtain the cyclodextrin modified cotton fiber containing the encapsulated essence. (2) Preparation of recycled cotton fiber modified polypropylene composite material Step one, polypropylene, elastomer and processing aid are uniformly mixed to obtain mixture A; Step two, whiskers and cyclodextrin modified cotton fiber are uniformly mixed to obtain mixture B; Step three, after setting the processing technology, mixture A is added from the main feeding port of the twin-screw extruder, and mixture B is added from the side feeding port (the side feeding port should be placed after the melting section and before the mixing section of the twin-screw extruder), then melt blending, cooling, granulation, drying are carried out to obtain the recycled cotton fiber modified polypropylene composite material.

12. The processing technology of the recycled cotton fiber modified polypropylene composite material with a fresh fragrance and soft touch according to claim 11, characterized in that: The processing temperature of the I-X zone of the twin-screw extruder is 135℃, 185℃, 185℃, 195℃, 195℃, 205℃, 220℃, 225℃, 225℃, and 215℃, respectively. The main screw rotation speed is 300-450 r / min, the water tank temperature is 23-50℃, and the melt temperature should be controlled within 230℃.

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