Preparation method of plant fiber material insole for relieving plantar pressure

Abstract

The present invention discloses a preparation method of a plant fiber material insole for relieving foot pressure. The method is as follows: The insole is divided into three regions: the forefoot, the foot arch, and the heel. According to the physical properties of the fiber felts with different aspect ratios, the insole component parameters with different shapes and different fiber partitions are designed; Bamboo fibers with different aspect ratios are selected, mixed with nanocellulose with water as the medium, and made into porous materials with light weight, different densities (different surface hardnesses), and creepable and shape-fixed by means of thermoforming with high temperature, short time, and fixed thickness. Cotton cloth is wrapped on the upper and lower surfaces, and the plant fiber insole is made by sewing at the splicing joints. The plant fiber insole made by the present invention can be more completely fitted to the sole of one's own foot, and can reduce the patient problems caused by wearing ill-fitting insoles.

Description

Technical Field

[0001] The present invention belongs to the technical field of bamboo processing and utilization, and particularly relates to a preparation method of an insole made of plant fiber material for relieving foot pressure. Background Art

[0002] The human foot sole is an uneven planar structure, which can generally be divided into three parts: the forefoot, the foot arch, and the heel. When a person stands statically or runs at a constant speed (10 Km / h), the stress on the sole of the foot is uneven and the pressure on the sole of the foot is inconsistent. Moreover, the sweat gland distribution density is relatively large in the foot arch and metatarsophalangeal parts, and it is easy to sweat, and the amount of sweat in the foot arch part is the largest. Therefore, it is necessary to improve the fit between the insole and the foot sole, that is, to partition the insole, and utilize the physical and mechanical properties of bamboo fiber felts with different aspect ratios to relieve the pain caused by uneven stress on the sole of the foot during long-term standing or exercise, and to increase the air permeability and sweat absorption performance, reduce the relative humidity of the foot, and improve the comfort level.

[0003] In daily life, uneven stress on the foot sole and moisture absorption and air permeability are important problems to be solved. As a buffer area between the foot sole and the shoe sole, the insole improves the uniformity of stress on the foot sole and the moisture absorption and air permeability. However, the preparation of traditional bamboo fiber insoles usually uses bamboo fibers for textile, and is made through steps such as carding, mixing, and sewing. The prepared bamboo fiber insole is similar to the traditional insole, has a certain moisture absorption and air permeability, and has no obvious self-adaptive performance. An insole that belongs specifically to oneself and can fit the foot sole more completely can reduce diseases caused by wearing ill-fitting insoles, such as plantar fasciitis, athlete's foot, foot arch collapse, forefoot pain, etc.

[0004] Nanocellulose is a biodegradable material with a nano size, high strength, large specific surface area, and large crystallinity, which is prepared by further deep processing of cellulose. Taking CNF as an example, it is prepared by mechanical treatment, usually with a diameter of 5 - 60 nm and a length of about several micrometers, and has extremely strong hydrogen bond binding ability. Therefore, nanofibers can be mixed with plant fibers to prepare a lightweight material that can be creep-shaped and fixed.

[0005] To solve the above problems, a preparation method of an insole made of plant fiber material for relieving foot pressure is proposed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a preparation method of an insole made of plant fiber material for relieving foot pressure in view of the deficiencies of the above-mentioned prior art. According to the physical properties (i.e., density, surface hardness, air permeability and water absorption performance, stress deformation characteristics) of bamboo fibers with different aspect ratios after felting, two parameters of different thicknesses and different fiber partitions are provided for the preparation of the soft surface of the insole, which can increase the sole support, improve the water absorption and air permeability performance, and fit the foot sole curve.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a preparation method of a plant fiber material insole for relieving foot pressure, characterized in that the method is as follows:

[0008] S1. Insole component design: Divide the insole into three areas: the forefoot, the foot arch, and the heel. The forefoot and the heel are made of low-density long plant fiber felts, and the foot arch is made of high-density short plant fiber felts;

[0009] S2. The preparation method of the long plant fiber felt in S1 is as follows:

[0010] Soak the long plant fibers in water for 4 - 6 hours, then stir until the long plant fibers are suspended in the water to obtain a mixture of long plant fibers and water; Pour the nano-cellulose solid-liquid mixture a into the mixture of long plant fibers and water, and stir and mix evenly to obtain the prepared solution a;

[0011] Pour the prepared solution a into the forefoot mold and the heel mold respectively, then perform pre-pressing respectively to obtain the compressed forefoot sample and the compressed heel sample; Perform hot pressing on the compressed forefoot sample and the compressed heel sample respectively to obtain the forefoot long plant fiber felt and the heel long plant fiber felt;

[0012] S3. The preparation method of the short plant fiber felt in S1 is as follows:

[0013] Soak the short plant fibers in water for 4 - 6 hours, then stir until the short plant fibers are suspended in the water to obtain a mixture of short plant fibers and water; Pour the nano-cellulose solid-liquid mixture b into the mixture of short plant fibers and water, and stir and mix evenly to obtain the prepared solution b;

[0014] Pour the prepared solution b into the foot arch mold, then perform pre-pressing to obtain the compressed foot arch sample; Perform hot pressing on the compressed foot arch sample to obtain the foot arch short plant fiber felt;

[0015] S4. Multi-layer stitching: Use the forefoot long plant fiber felt obtained in S2, the heel long plant fiber felt, and the foot arch short plant fiber felt obtained in S3 to splice as the insole soft surface, lay it flat on a layer of cotton cloth, then cover it with another layer of cotton cloth, and stitch at the splicing place to make a plant fiber insole.

[0016] Preferably, the long plant fibers in S2 and the short plant fibers in S3 are both bamboo fibers, cotton fibers or hemp fibers.

[0017] Preferably, the stirring frequency in S2 and the stirring frequency in S3 are both (48.3 ± 1.65) S -1 。

[0018] Preferably, in the mixture of long plant fibers and water in S2, the mass fraction of long plant fibers is 5-10 wt%, and the aspect ratio range of the long plant fibers is 618-713.

[0019] Preferably, in the nano-cellulose solid-liquid mixture a in S2, the solid content of nano-cellulose is 20%-30%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture a in the prepared solution a to the long plant fibers in the mixture of long plant fibers and water is (5-15):(85-95).

[0020] Preferably, in the mixture of short plant fibers and water in S3, the mass fraction of short plant fibers is 10-20 wt%, and the aspect ratio range of the short plant fibers is 264-383.

[0021] Short plant fibers with an aspect ratio of 264-383, due to their short length, are easily dispersed in water. After being mixed with nano-cellulose to form a felt, the fibers are easily overlapped, with fewer pores. Therefore, the formed fiber felt has a larger density and a higher surface hardness. Under the condition of applying the same pressure, the compression deformation of the short plant fibers is smaller, the supporting ability is stronger, the contact area of the fibers increases, and the hygroscopicity is better, but the air permeability is lower; while long plant fibers with an aspect ratio of 618-713, due to their long length, are not easily separated in water. After being mixed with nano-cellulose to form a felt, the fibers are loosely overlapped and have larger pores. Therefore, the formed fiber felt has a small density and a low surface density, a weak supporting ability, a small contact area of the fibers, a reduced hygroscopic property but a higher air permeability.

[0022] Preferably, in the nano-cellulose solid-liquid mixture b in S3, the solid content of nano-cellulose is 20%-30%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture b in the prepared solution b to the short plant fibers in the mixture of short plant fibers and water is (5-15):(85-95).

[0023] Preferably, the heights of the forefoot mold, the heel mold in S2 and the instep mold in S3 are all 10 mm; the heights of the prepared solution a poured into the forefoot mold and the heel mold in S2 are both 5-7 mm; the height of the prepared solution b poured into the instep mold in S3 is 5-7 mm.

[0024] Preferably, the thickness of the pre-pressing in S2 and S3 is 4-6 mm; the temperature of the hot pressing is 200 °C, and the time is 3-5 min / mm.

[0025] The present invention has the following advantages compared with the prior art:

[0026] 1. The present invention uses bamboo fibers with different aspect ratios to prepare insole, and utilizes its physical and mechanical properties after felting to ensure good moisture absorption, air permeability and foot sole fitting degree; based on the human foot sole structure and the foot sole stress when standing and running at a constant speed, it is proposed to prepare plant fiber insoles by zoning, and use the physical properties of bamboo fiber felt to meet the physiological structure of the foot sole. Nano-cellulose is used to bond bamboo fibers to form fiber felt, so that the fibers can be shaped, providing a certain support strength and surface hardness, and having the property of creep stability. During use, it can be shaped under force to form a fixed shape, so that it fits the foot sole structure better when used again, reducing the risk of foot diseases.

[0027] 2. According to the different pressures on the soles of the feet and the characteristics of the foot sole structure when a person stands or runs at a constant speed (10 km / h), the present invention divides the insole into three areas: the forefoot, the instep and the heel, and designs insole components with different shapes to increase the uniformity of the foot sole pressure distribution. According to the physical properties (i.e., density, surface hardness, air permeability and water absorption performance, and the characteristics of deformation under force) of bamboo fibers with different aspect ratios after felting, two parameters of different thicknesses and different fiber zoning are provided for the preparation of the soft surface of the insole, which can increase the foot sole support, improve the water absorption and air permeability performance, and fit the foot sole curve.

[0028] 3. The plant fiber insole made by the present invention can use bamboo fiber as the base and water as the medium, mix with nano-cellulose, stir evenly, and use the extremely strong hydrogen bond binding force of nano-cellulose as the adhesive between fibers to form a uniform suspension liquid; and adopt a thermoforming method with high temperature, short time and fixed thickness to evaporate water and link with each other to form a porous material (the middle layer of the insole) with light weight, different densities (different surface hardnesses) and creep stability, providing a certain support strength and surface hardness; combine the prepared soft surface components, wrap cotton cloth on the upper and lower surfaces, and sew the joints to produce insoles in batches. Utilizing the creep stability characteristic of the middle layer of the insole, the insole can be shaped under force to adapt to the standing and walking postures and foot sole structures of different people, reduce foot problems, and improve the air permeability and sweat absorption performance. At the same time, it can also be mass-produced, reducing the production and manufacturing costs, and meeting the consumption level of the public.

[0029] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0030] Figure 1 is the schematic diagram of the insole design and zoning of the present invention.

[0031] Figure 2 is the picture of the outer surface and cross-section of long plant fibers and short plant fibers in Embodiment 1.

[0032] Figure 3 is the schematic diagram of the stitching of plant fiber felt in the present invention.

[0033] Figure 4 It is a schematic diagram of preloading in Example 3. Detailed implementation manners

[0034] Example 1

[0035] The preparation method of the plant fiber material insole for relieving foot pressure in this example is as follows:

[0036] S1. Insole component design: According to the uneven structure of the sole, different stresses when standing or running at a constant speed on the sole, and the physical properties of plant fibers with different aspect ratios after forming felt, the insole is divided into three regions: the front sole, the foot arch, and the rear heel ( Figure 1 as shown), the front sole and the rear heel are made of low-density long plant fiber felt, and the foot arch is made of high-density short plant fiber felt;

[0037] S2. The preparation method of the long plant fiber felt in S1 is as follows:

[0038] Put the long plant fibers into water and soak for 5 h, then stir at a stirring frequency of (48.3 ± 1.65) S -1 under the condition until the long plant fibers are suspended in water to obtain a mixture of long plant fibers and water; pour the nano-cellulose solid-liquid mixture a into the mixture of long plant fibers and water and stir to mix evenly to obtain the prepared solution a; the mass fraction of long plant fibers in the mixture of long plant fibers and water is 7 wt%, and the aspect ratio range of the long plant fibers is 618 - 713; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture a is 25%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture a and long plant fibers in the mixture of long plant fibers and water in the prepared solution a is 10:90;

[0039] Pour the prepared solution a into the front sole mold and the rear heel mold respectively, then perform preloading respectively, and the preloading thickness is 4 mm to obtain the compressed front sole sample and the compressed rear heel sample; put the compressed front sole sample and the compressed rear heel sample into a hot press respectively and perform hot pressing and forming at a temperature of 200 °C and a time of 4 min / mm to obtain the front sole long plant fiber felt and the rear heel long plant fiber felt; the height of the prepared solution a poured into the front sole mold and the rear heel mold is 5 mm;

[0040] The surface hardness of the front sole fiber felt and the rear heel fiber felt made of long plant fibers is 25°, the water absorption rate in 10 min is 239.2%, the compression modulus is 1.1 MPa, and the density is 0.11 g / cm 3 ;

[0041] The preparation method of the short plant fiber felt described in S3 and S1 is as follows:

[0042] After soaking the short plant fibers in water for 5 h, stir at a stirring frequency of (48.3 ± 1.65) S -1 until the short plant fibers are suspended in water to obtain a mixture of short plant fibers and water; pour the nano-cellulose solid-liquid mixture b into the mixture of short plant fibers and water, and stir and mix evenly to obtain the configured solution b; the mass fraction of short plant fibers in the mixture of short plant fibers and water is 15 wt%, and the aspect ratio range of the short plant fibers is 264 - 383; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture b is 25%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture b to short plant fibers in the mixture of short plant fibers and water in the configured solution b is 10:90;

[0043] Pour the configured solution b into the instep mold, and then perform pre-pressing with a pre-pressing thickness of 4 mm to obtain a compressed instep sample; place the compressed instep sample in a hot press and perform hot pressing and forming at a temperature of 200 °C and a time of 4 min / mm to obtain an instep short plant fiber felt; the height of the configured solution b poured into the instep mold is 5 mm; the heights of the forefoot mold, the heel mold, and the instep mold are all 10 mm;

[0044] The surface hardness of the instep fiber felt made of short plant fibers is 43°, the water absorption rate in 10 min is 267.7%, the compression modulus is 1.9 MPa, and the density is 0.137 g / cm 3 ; both the long plant fibers described in S2 and the short plant fibers described in S3 are bamboo fibers, and the outer surfaces and cross-sections of the long plant fibers and the short plant fibers are as Figure 2 shown;

[0045] S4. Multi-layer stitching: Use the forefoot long plant fiber felt obtained in S2, the heel long plant fiber felt, and the instep short plant fiber felt obtained in S3 to splice as the soft surface of the insole, lay it flat on a layer of cotton cloth, then cover it with another layer of cotton cloth, and stitch at the splicing part ( Figure 3 as shown) to make a plant fiber insole.

[0046] The plant fiber insole prepared in this embodiment is used in cloth shoes. Since nano-cellulose has extremely strong hydrogen bond binding ability, after mixing nano-cellulose with bamboo fibers and performing hot forming, the originally loose bamboo raw fibers can be turned into a porous fiber felt, which has physical properties such as light weight, relatively hard surface, and creep and shape fixation. Using this property, due to the characteristics of the sole structure and the sole pressure distribution, the plant fiber insole can be force-shaped to fit the sole structure.

[0047] Example 2

[0048] The preparation method of the plant fiber material insole for relieving plantar pressure in this example is as follows:

[0049] S1. Insole component design: According to the uneven structure of the sole, different stresses during plantar standing or uniform running, and the physical properties of plant fibers with different aspect ratios after forming felt, the insole is divided into three areas: the forefoot, the instep, and the heel ( Figure 1 as shown), the forefoot and the heel are made of low-density long plant fiber felt, and the instep is made of high-density short plant fiber felt;

[0050] S2. The preparation method of the long plant fiber felt described in S1 is as follows:

[0051] After soaking the long plant fibers in water for 4 h, stir at a stirring frequency of (48.3 ± 1.65) S -1 until the long plant fibers are suspended in water to obtain a mixture of long plant fibers and water; pour the nano-cellulose solid-liquid mixture a into the mixture of long plant fibers and water and stir and mix evenly to obtain the configured solution a; the mass fraction of long plant fibers in the mixture of long plant fibers and water is 5 wt%, and the aspect ratio range of the long plant fibers is 618 - 713; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture a is 20%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture a to long plant fibers in the mixture of long plant fibers and water in the configured solution a is 5:95;

[0052] Pour the configured solution a into the forefoot mold and the heel mold respectively, and then perform pre-pressing. The pre-pressed thickness is 5 mm to obtain the compressed forefoot sample and the compressed heel sample; put the compressed forefoot sample and the compressed heel sample into a hot press and perform hot pressing and forming at a temperature of 200 °C and a time of 3 min / mm to obtain the forefoot long plant fiber felt and the heel long plant fiber felt; the height of the configured solution a poured into the forefoot mold and the heel mold is 6 mm;

[0053] The surface hardness of the forefoot fiber felt and the heel fiber felt made of long plant fibers is 18°, the water absorption rate in 10 min is 204.3%, the compression modulus is 0.9 MPa, and the density is 0.91 g / cm 3 ;

[0054] S3. The preparation method of the short plant fiber felt described in S1 is as follows:

[0055] After soaking the short plant fibers in water for 4 h, stir at a stirring frequency of (48.3 ± 1.65) S -1Under the condition of , stir until the short plant fibers are suspended in water to obtain a mixture of short plant fibers and water; pour the nano-cellulose solid-liquid mixture b into the mixture of short plant fibers and water, and stir and mix evenly to obtain the configured solution b; the mass fraction of short plant fibers in the mixture of short plant fibers and water is 10wt%, and the aspect ratio range of the short plant fibers is 264-383; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture b is 20%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture b to short plant fibers in the mixture of short plant fibers and water in the configured solution b is 5:95;

[0056] Pour the configured solution b into the footwell mold, and then perform pre-pressing with a pre-pressing thickness of 5 mm to obtain a compressed footwell sample; place the compressed footwell sample in a hot press and perform hot pressing at a temperature of 200 °C and a time of 3 min / mm to obtain a footwell short plant fiber felt; the height of the configured solution b poured into the footwell mold is 6 mm; the heights of the forefoot mold, the heel mold and the footwell mold are all 10 mm;

[0057] The surface hardness of the footwell fiber felt made of short plant fibers is 35°, the water absorption rate in 10 min is 255.9%, the compression modulus is 1.5 MPa, and the density is 0.106 g / cm 3 ; The long plant fibers in S2 and the short plant fibers in S3 are both cotton fibers;

[0058] S4. Multi-layer stitching: Splice the forefoot long plant fiber felt obtained in S2, the heel long plant fiber felt and the footwell short plant fiber felt obtained in S3 as the soft surface of the insole, lay it flat on a layer of cotton cloth, and then cover it with another layer of cotton cloth, and stitch at the splicing point ( Figure 3 as shown), and make a plant fiber insole.

[0059] The plant fiber insole prepared in this embodiment is used in leather shoes.

[0060] Example 3

[0061] The preparation method of the plant fiber material insole for sole pressure relief in this embodiment is as follows:

[0062] S1. Insole component design: According to the uneven structure of the sole, different stresses when standing or running at a constant speed on the sole, and the physical properties of plant fibers with different aspect ratios after forming felt, the insole is divided into three areas: the forefoot, the footwell and the heel ( Figure 1 as shown), the forefoot and the heel are made of low-density long plant fiber felt, and the footwell is made of high-density short plant fiber felt;

[0063] The preparation method of the long plant fiber felt described in S2 and S1 is as follows:

[0064] After soaking the long plant fibers in water for 6 h, stir at a stirring frequency of (48.3 ± 1.65) S -1 until the long plant fibers are suspended in water to obtain a mixture of long plant fibers and water; pour the nano-cellulose solid-liquid mixture a into the mixture of long plant fibers and water, and stir and mix evenly to obtain the prepared solution a; the mass fraction of long plant fibers in the mixture of long plant fibers and water is 10 wt%, and the aspect ratio range of the long plant fibers is 618 - 713; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture a is 30%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture a to long plant fibers in the mixture of long plant fibers and water in the prepared solution a is 15:85;

[0065] Pour the prepared solution a into the forefoot mold and the heel mold respectively, and then perform pre-pressing. The pre-pressed thickness is 6 mm to obtain the compressed forefoot sample and the compressed heel sample; put the compressed forefoot sample and the compressed heel sample into a hot press respectively and perform hot pressing and forming at a temperature of 200 °C and a time of 5 min / mm to obtain the forefoot long plant fiber felt and the heel long plant fiber felt; the height of the prepared solution a poured into the forefoot mold and the heel mold is 7 mm;

[0066] The surface hardness of the forefoot fiber felt and the heel fiber felt made of long plant fibers is 30°, the water absorption rate in 10 min is 254.8%, the compression modulus is 1.3 MPa, and the density is 0.15 g / cm 3 ;

[0067] The preparation method of the short plant fiber felt described in S3 and S1 is as follows:

[0068] After soaking the short plant fibers in water for 6 h, stir at a stirring frequency of (48.3 ± 1.65) S -1 until the short plant fibers are suspended in water to obtain a mixture of short plant fibers and water; pour the nano-cellulose solid-liquid mixture b into the mixture of short plant fibers and water, and stir and mix evenly to obtain the prepared solution b; the mass fraction of short plant fibers in the mixture of short plant fibers and water is 20 wt%, and the aspect ratio range of the short plant fibers is 264 - 383; the solid content of nano-cellulose in the nano-cellulose solid-liquid mixture b is 30%, and the mass ratio of nano-cellulose in the nano-cellulose solid-liquid mixture b to short plant fibers in the mixture of short plant fibers and water in the prepared solution b is 15:85;

[0069] Pour the configured solution b into the footwell mold, and then perform pre-pressing with a pre-pressed thickness of 6 mm to obtain a compressed footwell sample; place the compressed footwell sample in a hot press and perform hot pressing and forming at a temperature of 200 °C for 5 min / mm to obtain a footwell short plant fiber felt; the height of the configured solution b poured into the footwell mold is 7 mm; the heights of the forefoot mold, the heel mold, and the footwell mold are all 10 mm;

[0070] The surface hardness of the footwell fiber felt made of short plant fibers is 51°, the water absorption rate in 10 min is 271.3%, the compression modulus is 2.2 MPa, and the density is 0.144 g / cm 3 ; the long plant fibers described in S2 and the short plant fibers described in S3 are both hemp fibers;

[0071] S4. Multi-layer stitching: splice the forefoot long plant fiber felt obtained in S2, the heel long plant fiber felt, and the footwell short plant fiber felt obtained in S3 as the soft surface of the insole, lay it flat on a layer of cotton cloth, and then cover it with another layer of cotton cloth, and stitch at the splicing point ( Figure 3 as shown) to make a plant fiber insole.

[0072] The plant fiber insole (size 37) prepared in this embodiment is used in sports shoes. Information of the experimental personnel: female, height 160, weight 46 kg. After the experimental personnel ran 1 km wearing the sports shoes with the plant fiber insole of this embodiment, the soles of the feet of the experimental personnel remained dry, and the weight of the sports shoes was relatively light, indicating that the plant fiber insole of this embodiment has the effect of quickly absorbing water, meeting the requirement of quickly absorbing sweat after the feet sweat during daily exercise and keeping the feet dry.

[0073] The forefoot mold, the heel mold, and the footwell mold in Embodiments 1-3 need to be customized, or the molds of existing silicone insoles need to be modified. The upper mold is used for pre-pressing during pre-pressing, and the height of the protruding part of the upper mold is 8 mm; the schematic diagram of pre-pressing in Embodiment 3 is as Figure 4 shown.

[0074] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent changes made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. Preparation method of plant fiber material insole for relieving plantar pressure Characterized in that This method is as follows S1. Insole component design: Divide the insole into three areas: the forefoot, the foot arch, and the heel. The forefoot and the heel are made of low-density long plant fiber felts, and the foot arch is made of high-density short plant fiber felts; S2. Preparation method of the long plant fiber felt in S1 is as follows Soak the long plant fibers in water for 4 - 6 hours, then stir until the long plant fibers are suspended in water to obtain a mixture of long plant fibers and water; Pour the nano-cellulose solid-liquid mixture a into the mixture of long plant fibers and water, and stir and mix evenly to obtain the prepared solution a; The solid content of nano-cellulose in the nano-cellulose solid-liquid mixture a is 20% - 30%; Pour the prepared solution a into the forefoot mold and the heel mold respectively, then perform pre-pressing respectively to obtain the compressed forefoot sample and the compressed heel sample; Perform hot pressing on the compressed forefoot sample and the compressed heel sample respectively to obtain the forefoot long plant fiber felt and the heel long plant fiber felt; S3. Preparation method of the short plant fiber felt in S1 is as follows Soak the short plant fibers in water for 4 - 6 hours, then stir until the short plant fibers are suspended in water to obtain a mixture of short plant fibers and water; Pour the nano-cellulose solid-liquid mixture b into the mixture of short plant fibers and water, and stir and mix evenly to obtain the prepared solution b; The solid content of nano-cellulose in the nano-cellulose solid-liquid mixture b is 20% - 30%; Pour the prepared solution b into the foot arch mold, then perform pre-pressing to obtain the compressed foot arch sample; Perform hot pressing on the compressed foot arch sample to obtain the foot arch short plant fiber felt; S4. Multi-layer stitching: Stitch and splice the forefoot long plant fiber felt obtained in S2, the heel long plant fiber felt, and the foot arch short plant fiber felt obtained in S3 as the insole soft surface, lay it flat on a layer of cotton cloth, then cover it with another layer of cotton cloth, and stitch at the splicing points to make a plant fiber insole.

2. The preparation method of the plant fiber material insole for relieving plantar pressure according to claim 1 Characterized in that The long plant fibers in S2 and the short plant fibers in S3 are both bamboo fibers, cotton fibers or hemp fibers.

3. The preparation method of the plant fiber material insole for relieving plantar pressure according to claim 1 Characterized in that The frequencies of the stirring described in S2 and the stirring described in S3 are both (48.3 ± 1.65) s -1 .

4. The preparation method of the plant fiber material insole for relieving plantar pressure according to claim 1 Characterized in that The mass fraction of the long plant fibers in the mixture of long plant fibers and water in S2 is 5 - 10wt%, and the aspect ratio range of the long plant fibers is 618 - 713.

5. The preparation method of the plant fiber material insole for relieving plantar pressure according to claim 1 Characterized in that The mass ratio of the nano-cellulose in the nano-cellulose solid-liquid mixture a in the prepared solution a in S2 to the long plant fibers in the mixture of long plant fibers and water is (5 - 15):(85 - 95).

6. The preparation method of a plant fiber material insole for relieving plantar pressure according to claim 1, characterized in that, in the mixture of short plant fibers and water described in S3, the mass fraction of short plant fibers is 10-20 wt%, and the aspect ratio range of the short plant fibers is 264-383.

7. The preparation method of a plant fiber material insole for relieving plantar pressure according to claim 1, characterized in that, in the solution b after configuration described in S3, the mass ratio of the nanocellulose in the nanocellulose solid-liquid mixture b to the short plant fibers in the mixture of short plant fibers and water is (5-15):(85-95).

8. The preparation method of a plant fiber material insole for relieving plantar pressure according to claim 1, characterized in that, the heights of the forefoot mold, the heel mold described in S2 and the instep mold described in S3 are all 10 mm; the heights of the solution a after configuration poured into the forefoot mold and the heel mold in S2 are both 5-7 mm; the height of the solution b after configuration poured into the instep mold in S3 is 5-7 mm.

9. The preparation method of a plant fiber material insole for relieving plantar pressure according to claim 1, characterized in that, the thicknesses of the pre-pressing in S2 and the pre-pressing in S3 are both 4-6 mm; the temperatures of the hot pressing and forming in S2 and the hot pressing and forming in S3 are both 200 °C, and the time is both 3-5 min / mm.

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