China hemp fiber non-woven fabric as well as preparation method and application thereof

Abstract

The invention discloses a China hemp fiber non-woven fabric and a preparation method and application thereof, and belongs to the technical field of non-woven fabrics. The hemp fiber non-woven fabric provided by the invention has good air permeability, antibacterial property and liquid evaporation rate, that is, the hemp fiber non-woven fabric can be quickly dry and comfortable after absorbing liquid, and the softness of the hemp fiber non-woven fabric after absorbing the liquid tends to be increased; therefore, the composite material can be widely applied to preparation of hygienic products, particularly used as a surface layer of a sanitary towel, is mild, non-irritant, soft and easy to dry, and also has an excellent effect of inhibiting microorganisms and a good breathing effect.

Description

Technical Field

[0001] The invention belongs to the technical field of nonwoven fabrics, and in particular relates to a hemp fiber nonwoven fabric and a preparation method and application thereof. Background Art

[0002] Hemp, which originated in China, is the earliest textile raw material used by human society. It is a natural cellulose fiber that is biodegradable at the end of its service life. In other words, hemp is an abundant, renewable and environmentally friendly raw material.

[0003] Since products made of hemp have the effects of coolness, breathability, UV resistance, and natural antibacterial, hemp is widely used in medical, civil textile and other fields. However, there are some inevitable problems in the application of hemp, such as the high roughness of hemp, which leads to poor user experience when it is prepared into materials in contact with the human body; and the existing technology may affect its original air permeability and antibacterial properties while reducing its roughness. Therefore, most of the applications of hemp in the prior art are further modified or compounded with other fabrics. For example, patent CN117211007A discloses a hemp fiber blended spunlace nonwoven fabric for disposable underwear, which shows that the spunlace nonwoven fabric has good antibacterial properties, is non-irritating to the skin, soft and comfortable, etc., but the proportion of hemp fiber in this scheme is only 20-60%. Patent CN109576902A discloses a cotton and linen soft blended spunlace nonwoven fabric material, in which the proportion of hemp is only 5-50%. For another example, although patent CN117338989A discloses an antibacterial sanitary napkin made of all hemp fiber, an analysis of its technical solution shows that the surface layer is not made of original hemp fiber, but modified hemp fiber, specifically ammonium oxalate-complex enzyme modified hemp fiber cloth, which helps to effectively remove the blocking substances in the fiber mesh structure, increase the oxygen content, and is not conducive to the growth of anaerobic bacteria while retaining the antibacterial properties of hemp fiber. In addition, although patent CN117569003A provides an antibacterial non-woven fabric made of all hemp fiber, its components are not original hemp fiber, but the product of a series of treatments of original hemp fiber, such as cottonized hemp fiber, hemp antibacterial microcapsules, dicarboxyl hemp fiber, etc.

[0004] Therefore, how to use hemp fiber to provide a product with 100% hemp fiber as raw material and excellent antibacterial and breathable properties as well as good softness has become a research hotspot. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a hemp fiber non-woven fabric which has excellent air permeability, antibacterial properties and liquid evaporation rate and is gentle, soft and non-irritating to human skin.

[0006] To achieve the above object, in a first aspect of the present invention, the present invention provides a hemp fiber nonwoven fabric, the hemp fiber nonwoven fabric is composed of hemp fibers; the hemp fibers contain macropores with a pore size of >10 μm, mesopores with a pore size of 1-10 μm, and micropores with a pore size of <1 μm, and the total porosity of the hemp fibers is 30-50%;

[0007] In the hemp fiber, the porosity of macropores accounts for 48-65% of the total porosity, the porosity of mesopores accounts for 24-50% of the total porosity, and the porosity of micropores accounts for 2-12% of the total porosity;

[0008] When the moisture regain of the hemp fiber nonwoven fabric increases from 0% to 100%, the bending rigidity decreases by ≥2%.

[0009] As an implementation scheme of the present invention, when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the bending rigidity decreases by 3-5%.

[0010] As an embodiment of the present invention, the total porosity of the hemp fiber is 36-48%.

[0011] As an embodiment of the present invention, in the hemp fiber, the porosity of macropores accounts for 51-60% of the total porosity.

[0012] As an embodiment of the present invention, in the hemp fiber, the porosity of the mesopores accounts for 36-44% of the total porosity.

[0013] As an embodiment of the present invention, in the hemp fiber, the porosity of small pores accounts for 3-6% of the total porosity.

[0014] As an embodiment of the present invention, the hemp fiber has a fineness of >2000 Nm and a length of >28 mm.

[0015] As an embodiment of the present invention, the hemp fiber has a fineness of 2240-2600 Nm and a length of 28.3-35 mm.

[0016] In a second aspect of the present invention, the present invention provides a method for preparing the hemp fiber nonwoven fabric, the preparation method comprising the following steps:

[0017] S1. Break and beat the hemp stalks after rain and dew to obtain hemp skins;

[0018] S2, degumming the hemp skin using a composite bacterial solution, wherein the composite bacterial solution contains alkaliphilic Bacillus and Pseudomonas fluorescens in a mass ratio of 1:(1-2);

[0019] S3, placing the hemp fiber after the primary degumming in step S2 in a secondary degumming solution for secondary degumming to obtain degummed hemp fiber; the pH value of the secondary degumming solution is 12-13.5, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 9-10 mL / L;

[0020] S4, soaking the degummed hemp fiber in oil, and then deoiling and dehydrating it for humidification and curing; wherein the relative humidity of the humidification and curing treatment is 60-70%, and the temperature is ≥25°C;

[0021] S5, opening and combing the hemp fiber after the humidification and curing treatment to obtain hemp fiber with a length of more than 28 mm and a residual rubber rate of 5-20%;

[0022] S6. The hemp fiber is cleaned, combed and laid to obtain a fiber web; wherein the weight of the fiber web is ≥33g / m 2 ;

[0023] S7. The fiber web is subjected to a spunlace process and a spunlace post-process in sequence to obtain a hemp fiber non-woven fabric; wherein the spunlace process includes four spunlace processes, and the spunlace pressures in the first to fourth spunlace processes are 35-45 bar, 60-70 bar, 75-85 bar, and 85-95 bar, respectively.

[0024] As an embodiment of the present invention, the concentration of bacteria in the composite bacteria solution is (0.1-10)×10 -8 CFU / mL.

[0025] As an embodiment of the present invention, the solid-liquid ratio of the first degumming is 1 g: (5-15) mL.

[0026] As an embodiment of the present invention, the temperature of the first degumming is 32-36° C. and the time is 6-8 hours.

[0027] As an embodiment of the present invention, the solid-liquid ratio of the secondary degumming is 1g:(8-12)mL.

[0028] As an embodiment of the present invention, the temperature of the secondary degumming is 98-100° C., and the time of the secondary degumming is 60-120 min.

[0029] In the third aspect of the present invention, the present invention provides the use of the hemp fiber non-woven fabric in the preparation of sanitary products.

[0030] As an embodiment of the present invention, the sanitary products include any one of sanitary napkins, panty liners, band-aids, diapers, adult pull-up pants, and disposable underwear.

[0031] In a fourth aspect of the present invention, the present invention provides a sanitary napkin, the surface layer of the sanitary napkin is the hemp fiber non-woven fabric of the present invention.

[0032] As an embodiment of the present invention, the sanitary napkin further comprises an absorbent layer and a backing layer.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] When the moisture regain of a hemp fiber non-woven fabric provided by the present invention increases from 0% to 100%, the decrease in flexural rigidity is within a specific range, and the porosity of the hemp fiber in the hemp fiber non-woven fabric provided by the present invention and the proportion of the porosity of pores in different pore size ranges to the total porosity are within a certain range, and the fineness of the hemp fiber is within a specific range; the obtained hemp fiber non-woven fabric has good air permeability, antibacterial properties and liquid evaporation rate, that is, it can dry quickly after absorbing liquid and the softness will show an increasing trend after absorbing liquid; therefore, it can be widely used in the preparation of sanitary products, especially as the surface layer of sanitary napkins, which is not only mild and non-irritating, soft and easy to dry, but also has excellent microbial inhibition and good respiratory effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 These are photos of hemp skin and hemp fiber at different steps in Example 1:

[0036] a- a photograph of the hemp skin obtained after the treatment in step S1, b- a photograph of the hemp fiber obtained after the deoiling and dehydration in step S4, c- a photograph of the hemp fiber obtained after the humidification and health treatment in step S4;

[0037] Figure 2 This is a photograph of the hemp fiber nonwoven fabric prepared in Example 1:

[0038] a-Photograph of single-layer hemp fiber non-woven fabric, b-Photograph of multi-layer hemp fiber non-woven fabric;

[0039] Figure 3 This is a scanning electron microscope image of the hemp skin obtained after the treatment in step S1 in Example 1;

[0040] Figure 4 This is a scanning electron microscope image of the hemp fiber obtained after the treatment in step S5 in Example 1;

[0041] Figure 5 This is a photograph of the sanitary napkin product provided in Application Example 1:

[0042] a-photograph of the sanitary napkin product unfolded, b-photograph of the sanitary napkin product folded;

[0043] Figure 6This is a photo of the adult pull-up pants product provided in Application Example 2:

[0044] a-Photograph of the outside side of adult pull-up pants, b-Photograph of the inside side of adult pull-up pants. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0047] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0048] The reagents or instruments used in the present invention without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0049] In one embodiment of the present invention, the present invention provides a hemp fiber nonwoven fabric, the hemp fiber nonwoven fabric is composed of hemp fibers; the hemp fibers contain macropores with a pore size of >10 μm, mesopores with a pore size of 1-10 μm, and micropores with a pore size of <1 μm, and the total porosity of the hemp fibers is 30-50%;

[0050] In the hemp fiber, the porosity of macropores accounts for 48-65% of the total porosity, the porosity of mesopores accounts for 24-50% of the total porosity, and the porosity of micropores accounts for 2-12% of the total porosity;

[0051] When the moisture regain of the hemp fiber nonwoven fabric increases from 0% to 100%, the bending rigidity decreases by ≥2%.

[0052] The hemp fiber nonwoven fabric provided by the present invention has good air permeability and antibacterial properties, and also has good liquid evaporation rate (liquid includes water, blood, etc.) and softness.

[0053] Specifically, in the first aspect, the hemp fiber non-woven fabric provided by the present invention is composed of 100% original natural hemp fiber. Since the existing prepared hemp fiber fails to fundamentally solve the problems of coarseness and hardness of hemp fiber, it is difficult to spin 100% original natural hemp fiber. On the basis of solving the problems of coarseness and hardness, there will be excessive damage to the structure of hemp fiber, resulting in significant deterioration of the air permeability and antibacterial properties of hemp fiber. Therefore, the full hemp fiber non-woven fabric disclosed in the prior art is not composed of 100% natural original hemp fiber, but the original hemp fiber is chemically modified to improve the antibacterial property of the product, or the original hemp fiber is mixed with other fibers such as chemical fiber to reduce the difficulty of production; the present invention can realize the preparation of hemp fiber non-woven fabric with 100% original natural hemp fiber by controlling the specific pore structure and porosity of hemp fiber, without chemical modification, and the raw material is natural and safe; at the same time, there is no need to consider the blending ratio with other fibers, and the raw materials are simple and easy to prepare;

[0054] Secondly, the total porosity of hemp fiber in the hemp fiber non-woven fabric is 30-50%, the porosity of macropores with a pore size of more than 10 μm accounts for 48-65%, the porosity of mesopores with a pore size of 1-10 μm accounts for 24-50%, and the porosity of small pores with a pore size of less than 1 μm accounts for 2-12%; the total porosity range and the porosity ratio range of macropores, mesopores and small pores can better maintain the good natural properties of the original hemp fiber, and can even further improve the air permeability, antibacterial properties and evaporation rate of liquids of the hemp fiber non-woven fabric without modifying the hemp fiber, thereby achieving a more excellent comprehensive performance of the hemp fiber non-woven fabric prepared using the original hemp fiber;

[0055] On the third aspect, the hemp fiber non-woven fabric provided by the present invention uses 100% original hemp fiber and controls the pore structure and porosity of the hemp fiber within the range given by the present invention. On the basis of maintaining the good natural properties of the hemp fiber as much as possible, it can also effectively avoid the rigidity problem of the hemp fiber, so that when the regain of the prepared hemp fiber non-woven fabric increases from 0% to 100%, the bending stiffness decreases by ≥2%. The decrease in bending stiffness can ensure that the hemp fiber cloth has good softness, is gentle and non-irritating, and has better softness after absorbing liquid. The existing non-woven fabrics made of hemp fiber blends or other fibers do not have the characteristic of being softer after absorbing liquid, but will show an increase in hardness after absorbing liquid. That is, the hemp fiber non-woven fabric prepared by the present invention has a better user experience than the non-woven fabrics in the prior art.

[0056] Exemplarily, the total porosity of hemp fiber can be any point value between 30-50% or any two points in the range, such as 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, etc.

[0057] Exemplarily, in the hemp fiber, the proportion of the porosity of macropores to the total porosity can be any point value between 48-65% or any two points in the range, for example, it can be 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, etc.

[0058] Exemplarily, in the hemp fiber, the proportion of the porosity of the mesopores to the total porosity can be any point value between 24-50% or any two points in the range, such as 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, etc.

[0059] Exemplarily, in the hemp fiber, the proportion of the porosity of small pores to the total porosity can be any point value between 2-12% or any two point range values, such as 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc.

[0060] It should be noted that the total porosity of hemp fiber and the porosity of macropores, mesopores and micropores are obtained by mercury intrusion testing. Specifically, the mercury intrusion testing method includes the following steps: drying the hemp fiber at 50°C to constant weight (mass change rate of less than 1% in 1 hour), cutting it into 1 cm segments with a mass of less than 2 g, and then putting the cut hemp fiber into a mercury intrusion instrument for testing; the mercury intrusion method uses the conductivity of mercury, and the sensor collects the electrical information and converts it into the change of mercury, and then obtains the porosity information.

[0061] The pore radius of the macropores, mesopores and small pores is calculated by the Washburn equation (Pr = -2γcosθ), wherein the interfacial tension γ between mercury and air is 0.485 N / m, the contact angle θ between mercury and the material is 130°, the pore radius r is in nm, and P is the applied external pressure in Psia.

[0062] Exemplarily, when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the decrease in flexural stiffness may be any point value ≥2% or any two-point range value, such as 2-6%, 2-4%, 4-6%, 3-5%, etc., or may be 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, etc.

[0063] It should be noted that when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the decrease in flexural rigidity = (flexural rigidity at 0% moisture regain - flexural rigidity at 100% moisture regain) / flexural rigidity at 0% moisture regain × 100%;

[0064] Among them, the bending stiffness of the hemp fiber non-woven fabric at a moisture regain of 0% or 100% is tested using a YG207N automatic fabric stiffness tester, specifically:

[0065] (1) Determine and calculate the mass per unit area of ​​the sample according to GB / T4669;

[0066] (2) Randomly cut 12 specimens with a size of (25±1) mm × (250+1) mm; the long sides of 6 specimens are parallel to the longitudinal direction of the hemp fiber non-woven fabric, and the long sides of 6 specimens are parallel to the transverse direction of the hemp fiber non-woven fabric; the specimens are at least 100 mm away from the edge of the hemp fiber non-woven fabric;

[0067] (3) Place the sample on the platform with one end of the sample aligning with the front edge of the platform. Place the upper pressing plate on the sample and align them.

[0068] (4) Press the start button and push the specimen forward at a certain speed so that the specimen extends out of the front edge of the platform and bends under its own weight until the extended end of the specimen contacts the inclined surface. Record the extended length of the specimen.

[0069] (5) Take half of the extended length as the bending length, record four bending lengths for each sample, and calculate the average bending length of each sample; calculate the average bending length C of each sample in two directions in centimeters; calculate the average bending stiffness per unit width in two directions according to formula I, retaining three significant figures;

[0070] Formula I: G = m × C 3 ×10 -3 ;

[0071] Where G is the bending stiffness per unit width, in millinewton centimeters (mN cm); m is the mass per unit area of ​​the sample, in grams per square meter (g / m 2 ); C is the average bending length of the sample, in centimeters (cm).

[0072] In addition, a moisture regain of 0% refers to the state when the weight of the hemp fiber non-woven fabric is the dry weight; a moisture regain of 100% refers to the state when the hemp fiber non-woven fabric absorbs water and its weight is twice its dry weight; the state of achieving a moisture regain of 100% is achieved by spraying water on the surface of the hemp fiber non-woven fabric using a sprayer, combing it and leaving it to stand in a sealed bag for more than 4 hours, taking out the hemp fiber non-woven fabric, weighing it and calculating the moisture regain to 100%.

[0073] In one embodiment, when the moisture regain of the hemp fiber nonwoven fabric increases from 0% to 100%, the bending stiffness decreases by 3-5%.

[0074] Exemplarily, when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the decrease in flexural stiffness may be any point value between 3-5% or any two points in the range, for example, it may be 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, etc.

[0075] The present invention has found that when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the decrease in flexural rigidity will not only affect the softness of the hemp fiber non-woven fabric, but also have a certain impact on the liquid evaporation rate and antibacterial properties of the product. When the decrease in flexural rigidity is further selected to be 3-5%, the obtained product has better softness after liquid absorption and a higher liquid evaporation rate, that is, the liquid can evaporate faster after absorbing it, maintaining a dry and refreshing user experience, and the antibacterial properties are also better.

[0076] In one embodiment, the total porosity of the hemp fiber is 36-48%.

[0077] The present invention has found that hemp fiber has a loose porous structure, but the porosity range of hemp fiber obtained by each different treatment method is different. The porosity of hemp fiber will not only affect the air permeability of hemp fiber non-woven fabric, but also affect its antibacterial effect and softness. When the porosity of hemp fiber is further selected to be 36-48%, the air permeability and antibacterial properties of the obtained hemp fiber non-woven fabric are better, the liquid evaporation rate is larger, and the softness is excellent.

[0078] In one embodiment, in the hemp fiber, the porosity of macropores accounts for 51-60% of the total porosity.

[0079] In one embodiment, in the hemp fiber, the porosity of mesopores accounts for 36-44% of the total porosity.

[0080] In one embodiment, in the hemp fiber, the porosity of small pores accounts for 3-6% of the total porosity.

[0081] The present invention has found that when the porosity of the macropores, mesopores and micropores of the hemp fiber are further selected to be within the above ranges, the comprehensive performance of the obtained hemp fiber non-woven fabric is better.

[0082] In one embodiment, the hemp fiber has a fineness of >2000 Nm and a length of >28 mm.

[0083] In one embodiment, the hemp fiber has a fineness of 2240-2600 Nm and a length of 28.3-35 mm.

[0084] It should be noted that the fineness of hemp fiber is obtained by the mid-section weighing method with reference to GB / T 18147.4-2015, and the length is obtained by the manual grouping weighing method with reference to GB / T 18147.3-2015.

[0085] Exemplarily, the fineness of hemp fiber can be any point value between 2240-2600Nm or any two points in the range, such as 2240Nm, 2260Nm, 2280Nm, 2300Nm, 2320Nm, 2340Nm, 2360Nm, 2380Nm, 2400Nm, 2420Nm, 2440Nm, 2460Nm, 2480Nm, 2500Nm, 2520Nm, 2540Nm, 2560Nm, 2580Nm, 2600Nm, etc. The length of hemp fiber can be any point value or any two point range value between 28.3-35mm, for example, it can be 28.3mm, 28.5mm, 28.8mm, 29.0mm, 29.3mm, 29.5mm, 29.8mm, 30.0mm, 30.3mm, 30.5mm, 30.8mm, 31.0mm, 31.3mm, 31.5mm, 31.8mm, 32.0mm, 32.3mm, 32.5mm, 32.8mm, 33.0mm, 33.3mm, 33.5mm, 33.8mm, 34.0mm, 34.3mm, 34.5mm, 34.8mm, 35.0mm, etc.

[0086] The present invention has found that the fineness and length of hemp fiber will affect the softness and liquid evaporation rate of hemp fiber to a certain extent. When the fineness and length of hemp fiber are further selected within the above range, the obtained product has better softness and faster liquid evaporation.

[0087] In one embodiment of the present invention, the present invention provides a method for preparing the hemp fiber nonwoven fabric, the preparation method comprising the following steps:

[0088] S1. Break and beat the hemp stalks after rain and dew to obtain hemp skins;

[0089] S2, degumming the hemp skin using a composite bacterial solution, wherein the composite bacterial solution contains alkaliphilic Bacillus and Pseudomonas fluorescens in a mass ratio of 1:(1-2);

[0090] S3, placing the hemp fiber after the primary degumming in step S2 in a secondary degumming solution for secondary degumming to obtain degummed hemp fiber; the pH value of the secondary degumming solution is 12-13.5, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 9-10 mL / L;

[0091] S4, soaking the degummed hemp fiber in oil, and then deoiling and dehydrating it for humidification and curing; wherein the relative humidity of the humidification and curing treatment is 60-70%, and the temperature is ≥25°C;

[0092] S5, opening and combing the hemp fiber after the humidification and curing treatment to obtain hemp fiber with a length of more than 28 mm and a residual rubber rate of 5-20%;

[0093] S6. The hemp fiber is cleaned, combed and laid to obtain a fiber web; wherein the weight of the fiber web is ≥33g / m 2 ;

[0094] S7. The fiber web is subjected to a spunlace process and a spunlace post-process in sequence to obtain a hemp fiber non-woven fabric; wherein the spunlace process includes four spunlace processes, and the spunlace pressures in the first to fourth spunlace processes are 35-45 bar, 60-70 bar, 75-85 bar, and 85-95 bar, respectively.

[0095] The preparation method of the hemp fiber non-woven fabric provided by the present invention does not require the introduction of special devices, is easy to operate, can efficiently produce the hemp fiber non-woven fabric, and is beneficial to actual production.

[0096] It should be noted that the residual rubber rate of hemp fiber is tested by referring to the residual rubber rate test method in Part 2 of GB / T 18147.2-2008.

[0097] Exemplarily, the residual rubber rate of hemp fiber can be any point value between 5-20% or any two points in the range, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, etc.

[0098] The present invention has been found that the sequential primary and secondary degumming have a certain influence on the porosity of hemp fiber and the proportion of porosity of different pore sizes. When the primary and secondary degumming of the present invention are selected, the pore structure characteristics of the prepared hemp fiber are within the scope of the present invention, thereby being able to prepare a hemp fiber non-woven fabric with excellent comprehensive performance.

[0099] Specifically, the present invention defines that the composite bacterial solution used in a degumming process contains alkaliphilic Bacillus and fluorescing Pseudomonas in a mass ratio of 1: (1-2), that is, alkaliphilic Bacillus and fluorescing Pseudomonas are selected for compounding. On the one hand, alkaliphilic Bacillus and fluorescing Pseudomonas are naturally widely available and easy to obtain; on the other hand, alkaliphilic Bacillus can produce alkaline β-mannanase well, and fluorescing Pseudomonas can stably produce pectinase and hemicellulase. The two are compounded in a certain ratio to form a composite bacterial solution. Under the combined action of the above-mentioned enzyme types produced mainly and other enzymes produced, the composite bacterial solution can not only be used for the subsequent The combined effect of the subsequent secondary degumming can achieve an excellent degumming effect, and can achieve a balance in the contents of cellulose, hemicellulose and lignin in the hemp fiber within an appropriate degumming rate range, so that the hemp fiber has a suitable bonding force in the subsequent combing and web laying, and can be successfully combed and web laid to prepare hemp fiber non-woven fabrics; and the primary degumming process of the above-mentioned specific types of microorganisms is relatively mild, and the produced enzymes have excellent compounding effects, which can effectively and gently enzymatically hydrolyze the gelatinous components in the hemp skin, while changing the pore structure and porosity of the hemp fiber without destroying the basic supporting structure of the hemp fiber. The secondary degumming defined in the present invention is to place the hemp fiber after the primary degumming treatment in a secondary degumming solution for degumming, the pH value of the secondary degumming solution is 12-13.5, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 9-10mL / L; after the primary degumming treatment, degumming is carried out in a secondary degumming solution within a specific pH value range and a specific volume concentration of hydrogen peroxide, which can further remove the colloid and maintain the balance of the content of vitamins, lignin and hemicellulose, thereby changing the pore structure and porosity of the hemp fiber, maintaining the appropriate bonding force between the hemp fibers, thereby laying the foundation for achieving the excellent comprehensive effect of the hemp fiber non-woven fabric.

[0100] In one embodiment, the pH value of the secondary degumming solution is adjusted to 12-13.5 by adding sodium hydroxide.

[0101] The present invention achieves a pH value of 12-13.5 for the secondary degumming solution by selecting natural, non-toxic and harmless sodium hydroxide. On the one hand, it has good environmental protection, and on the other hand, it will not leave any residue. The hemp fiber non-woven fabric prepared from the hemp fiber obtained by adjusting the pH value using sodium hydroxide is mild, non-irritating and highly safe.

[0102] In one embodiment, the concentration of bacteria in the composite bacteria solution is (0.1-10)×10 -8 CFU / mL.

[0103] In one embodiment, the solvent of the composite bacterial solution is water. The preparation method of the composite bacterial solution is: adding alkaliphilic Bacillus and fluorescens to water at a mass ratio of 1: (1-2) to obtain the composite bacterial solution.

[0104] In one embodiment, the solid-to-liquid ratio of a degumming process is 1 g: (5-15) mL.

[0105] In one embodiment, the temperature of the first degumming is 32-36° C., and the time is 6-8 hours.

[0106] In one embodiment, the solid-to-liquid ratio of the secondary degumming is 1 g: (8-12) mL.

[0107] In one embodiment, the temperature of the secondary degumming is 98-100° C., and the time of the secondary degumming is 60-120 min.

[0108] The present invention finds that in the primary and secondary degumming treatments, the combination of specific types of microorganisms, the pH value of the secondary degumming solution, and the volume concentration of hydrogen peroxide can affect the pore structure characteristics of hemp fibers. Further optimization of parameters in the primary and secondary degumming treatment processes can effectively improve the degumming efficiency.

[0109] In one embodiment, during the secondary degumming, an auxiliary agent and a penetrant may be added to the secondary degumming solution.

[0110] The present invention has no specific requirements for the selection of auxiliary agents and penetrants, and conventionally selectable substances in the art can be selected. For example, the auxiliary agent includes at least one of sodium metabisulfite and trisodium phosphate, and the penetrant includes at least one of the penetrant JFC series, penetrant OE-35, penetrant SF, penetrant T, penetrant OEP-70, and penetrant AEP; the mass concentration of the auxiliary agent and the penetrant can be 0.8-1g / mL.

[0111] The present invention has found that humidification treatment can avoid damage to hemp fiber in the subsequent opening, combing and web laying stages, thereby better preserving the structural and functional characteristics of hemp fiber and achieving good comprehensive performance of hemp fiber. Exemplarily, the relative humidity of humidification treatment can be any point value or any two-point range value between 60-70%, such as 60%, 62%, 64%, 66%, 68%, 70%, etc.; the temperature can be any point value or any two-point range value ≥25°C, such as 25-30°C, 25-35°C, 25-40°C, etc.

[0112] In one embodiment, the length of the hemp fiber is 28.3-35 mm.

[0113] The present invention has found that the length of hemp fiber has a significant effect on whether the web can be successfully laid. When the length of the hemp fiber is selected within the range given by the present invention, especially 28.3-35 mm, the web can be successfully laid and the hemp fiber non-woven fabric can be prepared. Exemplarily, the length of the hemp fiber can be any point value or any two point range value between 28.3-35mm, such as 28.3mm, 28.5mm, 28.8mm, 29.0mm, 29.3mm, 29.5mm, 29.8mm, 30.0mm, 30.3mm, 30.5mm, 30.8mm, 31.0mm, 31.3mm, 31.5mm, 31.8mm, 32.0mm, 32.3mm, 32.5mm, 32.8mm, 33.0mm, 33.3mm, 33.5mm, 33.8mm, 34.0mm, 34.3mm, 34.5mm, 34.8mm, 35.0mm, etc.

[0114] The present invention has found that the laying method and the quantitative range of the fiber web in the preparation process of the non-woven fabric will affect the uniformity of the hemp fiber arrangement and the interaction between the hemp fibers, and will also have a certain impact on the pore structure of the prepared hemp fibers, thereby affecting the comprehensive performance of the non-woven fabric; using the cross-laying of the present invention and the quantitative range of the fiber web in the laying under the parameters of the hemp fiber provided by the present invention can make the prepared hemp fiber non-woven fabric evenly stressed, avoid local stress concentration and other problems, and can further improve the pore structure of the hemp fiber used in the laying; thereby helping to achieve good air permeability, antibacterial properties, softness and liquid evaporation rate of the hemp fiber non-woven fabric.

[0115] In one embodiment, the basis weight of the fiber web in the laid web is 33-38 g / m 2 .

[0116] For example, the basis weight of the fiber web in the web laying process may be 33-38 g / m 2 Any point value or any range of two points in the range, for example, 33g / m 2 , 34g / m 2 , 35g / m 2 , 36g / m 2 , 37g / m 2 , 37g / m 2 wait.

[0117] The present invention has found that the hydroentanglement process will affect the entanglement effect of the hemp fiber web formed after laying, and the parameters in the hydroentanglement process will also affect the pore structure of the hemp fibers in the fiber web; by selecting the multi-pass hydroentanglement process of the present invention, specifically four-pass hydroentanglement processes to hydroentangle the hemp fiber web after laying, and limiting the hydroentanglement pressure range of the first to fourth hydroentanglement processes, the entanglement effect of the hemp fiber web can be effectively enhanced, and the pore structure of the hemp fibers in the fiber web can be further improved, thereby achieving good air permeability and antibacterial properties of the subsequently prepared hemp fiber non-woven fabric, and also making the obtained hemp fiber non-woven fabric have excellent softness and excellent liquid evaporation rate.

[0118] Exemplarily, the hydroentanglement pressure in the first hydroentanglement process can be any point value or any range value between 35-45 bar, such as 35 bar, 37 bar, 39 bar, 40 bar, 42 bar, 45 bar, etc.; the hydroentanglement pressure in the second hydroentanglement process can be any point value or any range value between 60-70 bar, such as 60 bar, 62 bar, 64 bar, 66 bar, 68 bar, 70 bar, etc.; the hydroentanglement pressure in the third hydroentanglement process can be any point value or any range value between 75-85 bar, such as 75 bar, 77 bar, 79 bar, 80 bar, 82 bar, 85 bar, etc.; the hydroentanglement pressure in the fourth hydroentanglement process can be any point value or any range value between 85-95 bar, such as 85 bar, 87 bar, 89 bar, 90 bar, 92 bar, 95 bar, etc.

[0119] The present invention has no requirements on the method of rain and dew hemp, and can adopt the conventional method of rain and dew hemp, that is, the original hemp stems are spread flat on the field, and the purpose of degumming is achieved under sunlight and rain and dew soaking; the factors affecting the rain and dew hemp mainly include temperature, time, moisture, light and the type of microorganisms.

[0120] In one embodiment, the primary degumming process further includes inactivation, filtration, collection of filter residues and washing.

[0121] In one embodiment, the inactivation temperature is 95-100°C.

[0122] In one embodiment, the cleaning is washing with water.

[0123] In one embodiment, the secondary degumming treatment further includes oxygen bleaching and acid washing.

[0124] Oxygen bleaching is to immerse the hemp fiber after secondary degumming in an oxygen bleaching agent. The present invention has no particular limitation on the selection of the oxygen bleaching agent, and a stabilizer can be added to the oxygen bleaching agent. The stabilizer can be conventionally selected, for example, the stabilizer includes at least one of sodium silicate, non-silicon stabilizer, polyhydroxycarboxylate, magnesium salt, and nitride stabilizer, and the mass percentage of the stabilizer is 0.3-0.6%.

[0125] The present invention has no special requirements on the immersion temperature and time during the oxygen bleaching process, and the effects of the present invention can be achieved within the conventional immersion temperature and time range in the art.

[0126] Exemplarily, the immersion temperature is 98-100° C. and the immersion time is 60-90 min.

[0127] The present invention has no special requirements for pickling. The pH value of the system after pickling can be 7, which can completely neutralize the natural alkaline substances added in the secondary degumming process, thereby ensuring the mildness, non-irritation and safety of the hemp fiber.

[0128] For example, the pickling may be performed using acetic acid, with the addition ratio of acetic acid being 0.01-0.02%.

[0129] In one embodiment, in step S4, the oil used in the oil immersion treatment is a mixture of vegetable oil, mineral oil and water, and the treatment time is 10-14 hours.

[0130] The present invention has found that oil treatment can increase the lubricity between hemp fibers and reduce the damage to hemp fibers caused by opening, combing, and laying during the subsequent preparation of hemp fiber non-woven fabrics, thereby better maintaining or even improving the structural characteristics of the prepared hemp fibers and achieving the preparation of hemp fiber non-woven fabrics with excellent comprehensive effects.

[0131] The present invention has no special requirements on the types of vegetable oil and mineral oil, and any vegetable oil and mineral oil that can be conventionally used for fiber oil treatment can be used. Exemplarily, the vegetable oil includes at least one of palm oil, soybean oil, rapeseed oil, peanut oil, corn oil, and olive oil; the mineral oil includes at least one of mineral oil, petrolatum, mineral wax, paraffin, microcrystalline wax, ozokerite, and montan wax.

[0132] In one embodiment, the mass ratio of vegetable oil to mineral oil is (0.8-1.2):1.

[0133] The present invention has found that when the mass ratio of vegetable oil to mineral oil in the oil immersion treatment is (0.8-1.2):1, the oil immersion effect is better.

[0134] Exemplarily, the oil immersion treatment time may be any point value or any two point range values ​​between 50-70 min, such as 50 min, 55 min, 60 min, 65 min, 70 min, etc.

[0135] In one embodiment, the oil-immersion treatment is followed by leaving the sample for 10-14 hours before de-oiling and dehydration.

[0136] In one embodiment, in step S4, the humidification treatment time is 12-48 hours.

[0137] The present invention has no special requirements for the opening and combing after the humidification and curing treatment, and conventional operations in the art can be adopted.

[0138] In one embodiment, in step S6, the cleaning process is to compact the hemp fibers and then loosen, remove impurities and mix them through a carding machine.

[0139] In one embodiment, in step S6, the combing is to further loosen and comb the cleaned hemp fibers to form a fiber web.

[0140] The present invention has no special requirements for opening and combing, and conventional equipment and conventional operation methods in the field can be used.

[0141] In one embodiment, in step S7, the post-treatment of spunlacing includes oxygen bleaching, drying and impurity separation, wherein the oxygen bleaching is to immerse the hemp fiber nonwoven fabric after the spunlacing process in an oxygen bleaching agent.

[0142] The present invention has no special requirements for the selection of oxygen bleaching agent, and any conventional oxygen bleaching agent that can be used for non-woven fabrics can be used.

[0143] Exemplarily, the oxygen bleaching agent may be an aqueous solution of hydrogen peroxide and sodium hydroxide, wherein the mass percentage of hydrogen peroxide in the oxygen bleaching agent is 1.5-2%, and the mass percentage of sodium hydroxide is 1.5-2%.

[0144] The present invention has no special requirements on the immersion temperature and time during the oxygen bleaching process, and the effects of the present invention can be achieved within the conventional immersion temperature and time range in the art.

[0145] Exemplarily, the immersion temperature is 98-100° C. and the immersion time is 60-90 min.

[0146] The present invention has no special requirements for the drying process and the impurity separation process, and the purpose of the present invention can be achieved by adopting conventional drying methods and impurity separation methods in the art.

[0147] In one embodiment of the present invention, the present invention provides the use of hemp fiber nonwoven fabric in the preparation of sanitary products.

[0148] The hemp fiber nonwoven fabric provided by the present invention has excellent air permeability, antibacterial property and good softness, especially after absorbing liquid, the bending stiffness shows a significant downward trend, that is, it has a trend of becoming softer with use, and the user experience is good; at the same time, the hemp fiber nonwoven fabric provided by the present invention also has a good liquid evaporation rate, and the liquid can evaporate quickly after absorbing liquid, thereby maintaining good dryness, and can further avoid the growth of microorganisms, and enhance the antibacterial performance. Therefore, it can be widely used in the preparation of sanitary products.

[0149] In one embodiment, the sanitary product includes any one of a sanitary napkin, a panty liner, a Band-Aid, a diaper, an adult pull-up pants, and a disposable undergarment.

[0150] In one embodiment of the present invention, the present invention provides a sanitary napkin, the surface layer of the sanitary napkin is the hemp fiber non-woven fabric of the present invention.

[0151] The surface layer of the sanitary napkin provided by the present invention uses the hemp fiber non-woven fabric of the present invention. On the first aspect, the hemp fiber non-woven fabric has high air permeability, and when applied to the preparation of the surface layer of the sanitary napkin, it can ensure good air permeability; on the second aspect, the hemp fiber non-woven fabric has good antibacterial properties, and when applied to the surface layer, it can prevent the reproduction and growth of microorganisms, thereby achieving excellent antibacterial effects; on the third aspect, the hemp fiber has excellent softness, and the softness shows an increasing trend after absorbing liquid. When applied to the preparation of the surface layer of the sanitary napkin, it will not cause friction irritation to the skin, has mild characteristics, and provides good user experience; on the fourth aspect, the hemp fiber has a good liquid evaporation rate. When used as a surface layer in the preparation of the sanitary napkin, it can evaporate quickly after absorbing liquid, thereby improving the dryness during use, enhancing the user experience, and avoiding the problem of microbial growth caused by slow evaporation of the liquid, that is, it can ensure a long-term antibacterial effect.

[0152] In one embodiment, the sanitary napkin further comprises an absorbent layer and a backing layer.

[0153] The present invention has no particular limitation on the materials of the absorbent layer and the bottom layer of the sanitary napkin, and any materials conventionally applicable to the absorbent layer and the bottom layer of sanitary napkins can be used.

[0154] Exemplarily, the material of the absorption layer may be a polymer absorbent material, fiber, etc. The polymer absorbent material includes at least one of polyethylene and polypropylene, and the fiber includes at least one of cotton fiber and bamboo pulp paper.

[0155] Exemplarily, the bottom layer may be a PE film, a non-base fabric composite film, or the like.

[0156] Example 1

[0157] An embodiment of the present invention provides a hemp fiber nonwoven fabric, and a method for preparing the hemp fiber nonwoven fabric comprises the following steps:

[0158] S1. Placing hemp stalks in the field for rain and dew retting to obtain rain and dew hemp. The temperature of the rain and dew retting is 18-30°C for 25 days. After the rain and dew retting, the hemp stalks are collected and crushed. Then, the woody parts and impurities of the crushed hemp stalks are removed to obtain hemp skin. The obtained hemp skin is photographed as shown in Figure 1 As shown in a;

[0159] S2. Place the hemp skin in a biological degumming pot, add a composite bacterial solution at a temperature of 35°C according to a solid-liquid ratio of 1g:10mL (the solvent in the composite bacterial solution is water, and the total concentration of alkaliphilic Bacillus and fluorescent Pseudomonas in the composite bacterial solution is 10 -8 CFU / mL, the mass ratio of alkaliphilic Bacillus and fluorescens is 1:1, wherein the deposit number of alkaliphilic Bacillus is CCTCC M2016316, and the deposit number of fluorescens is CGMCC No.3839), and the biological degumming treatment is maintained at 35°C for 7 hours; after the biological degumming treatment is completed, it is heated to 95°C for inactivation, and then filtered, and the filter residue is collected and washed with clean water;

[0160] S3, adding the filter residue after washing in step S2 and the secondary degumming solution to the secondary degumming pot at a solid-liquid ratio of 1g:10mL, and degumming at 98°C for 90min. After the secondary degumming, take out the hemp fiber, wash it three times with water, add it to the oxygen bleaching agent at a solid-liquid ratio of 1g:10mL, and oxygen bleach it at 98°C for 60min. After the oxygen bleaching, wash it three times with water, then add acetic acid aqueous solution (the mass percentage of acetic acid in the acetic acid aqueous solution is 0.02%) to wash until the pH value of the system is 7, and finally wash it with water and spin dry;

[0161] The pH value of the secondary degumming solution is 12.4, the solutes include sodium hydroxide, hydrogen peroxide, sodium pyrosulfite, trisodium phosphate and penetrant JFC, and the solvent is water; in the secondary degumming solution, the volume concentration of hydrogen peroxide is 10 mL / L, the mass concentration of sodium pyrosulfite is 0.9 g / L, the mass concentration of trisodium phosphate is 0.9 g / L, and the mass concentration of penetrant JFC is 0.9 g / L;

[0162] The solutes of the oxygen bleaching agent include hydrogen peroxide, sodium hydroxide and sodium silicate, and the solvent is water; in the oxygen bleaching agent, the mass percentage of hydrogen peroxide is 2%, the mass percentage of sodium hydroxide is 0.5%, and the mass percentage of sodium silicate is 0.5%;

[0163] S4, immersing the hemp fiber after drying in step S3 in an oiling agent and keeping it for 60 minutes, draining the oiling agent after the oiling is completed, and letting it stand for 12 hours, and then deoiling and dehydrating; then humidifying and curing the hemp fiber after deoiling and dehydration, and keeping it in an environment with a relative humidity of 65% and a temperature of 30°C for 24 hours;

[0164] The solute of the immersion oil agent is soybean oil and mineral oil in a mass ratio of 1:1, the solvent is water, and the mass ratio of the soybean oil and mineral oil to water is 1:10;

[0165] The photo of hemp fiber after deoiling and dehydration is as follows Figure 1 As shown in b, the photograph of hemp fiber after humidification and health treatment is as follows Figure 1 As shown in c;

[0166] S5, loosening, combing, and compacting the hemp fiber after the humidification and health treatment in step S4 to obtain hemp fiber;

[0167] S6, the hemp fiber prepared in step S5 is opened, cleaned and mixed by a carding machine, then enters a hemp bin through a hemp suction machine, and then enters multiple carding machines to card into a fiber web, and then the fiber webs formed by multiple carding machines are combined and stacked, cross-laid, and the laying parameters are controlled so that the weight of the fiber web is 36g / m 2 ;

[0168] S7, the fiber web after cross-laying in step S6 is spunlaced by a rotary drum spunlacing machine, and a total of four spunlacing processes are performed, and the spunlacing pressures in the first to fourth spunlacing processes are 40 bar, 65 bar, 80 bar, and 90 bar, respectively, and a spunlaced hemp fiber non-woven fabric is obtained after the spunlacing; then the spunlaced hemp fiber non-woven fabric is added to an oxygen bleaching agent at a solid-liquid ratio of 1 g:10 mL, and oxygen bleached at 98°C for 75 minutes, and after the oxygen bleaching is completed, it is washed with water three times and dried, and finally dried and impurities are removed to obtain a hemp fiber non-woven fabric;

[0169] The solute of the oxygen bleaching agent includes hydrogen peroxide and sodium hydroxide, and the solvent is water; in the oxygen bleaching agent, the mass percentage of hydrogen peroxide is 2%, and the mass percentage of sodium hydroxide is 1.5%;

[0170] The photograph of the prepared hemp fiber nonwoven fabric is as follows: Figure 2 As shown in a, Figure 2 b in the middle shows a photograph taken when the hemp fiber nonwoven fabric is further prepared into multiple layers.

[0171] Examples 2-6 and Comparative Examples 1-3

[0172] Examples 2-6 and comparative examples 1-3 respectively provide a hemp fiber non-woven fabric. The parameters of the hemp fiber non-woven fabrics in each example and comparative example are shown in Table 1 below.

[0173] After testing, the pH value of the secondary degumming solution and the humidity of the humidification treatment were adjusted on the basis of Example 1 to achieve the parameters of the hemp fiber non-woven fabric of Examples 2-3 in Table 1.

[0174] Through experiments, the temperatures of the first degumming and the second degumming were adjusted on the basis of Example 1 to achieve the parameters of the hemp fiber nonwoven fabrics of Examples 4-5 in Table 1.

[0175] After testing, the mass ratio of alkaliphilic Bacillus and fluorescing Pseudomonas in the composite bacterial solution in the first degumming and the volume concentration of hydrogen peroxide in the secondary degumming solution in the second degumming were adjusted on the basis of Example 1 to achieve the parameters of the hemp fiber non-woven fabric in Example 6 in Table 1.

[0176] After testing, the temperature and time of the first degumming and the second degumming were adjusted on the basis of Example 1 to achieve the parameters of the hemp fiber nonwoven fabric of Comparative Example 1 in Table 1.

[0177] After testing, the parameters of the hemp fiber nonwoven fabric of Comparative Examples 2-3 in Table 1 were achieved by adjusting the basis of Example 1 in terms of the basis weight of the fiber web and the parameters of the spunlace.

[0178] It should be noted that Examples 2-6 and Comparative Examples 1-3 include but are not limited to the above-mentioned methods given by the inventors to adjust the parameters in Table 1 through experiments, and the above-mentioned methods selected and adjusted through experiments are only given as exemplary descriptions.

[0179] Table 1

[0180]

[0181]

[0182] In the above Table 1, the test methods of each parameter are as follows:

[0183] 1. The total porosity of hemp fiber, the proportion of macropores (pore size > 10 μm) in the total porosity, the proportion of mesopores (pore size 1-10 μm) in the total porosity and the proportion of small pores (pore size < 1 μm) in the total porosity: measured by mercury intrusion method, specifically:

[0184] The hemp fiber was dried at 50°C to constant weight (mass change rate of less than 1% in 1 hour), and then cut into 1 cm segments with a mass of less than 2 g. The cut hemp fiber was then placed in a mercury intrusion instrument for testing.

[0185] The pore radius of the macropores, mesopores and small pores is calculated by the Washburn equation (Pr = -2γcosθ), wherein the interfacial tension γ between mercury and air is 0.485 N / m, the contact angle θ between mercury and the material is 130°, the pore radius r is in nm, and P is the applied external pressure in Psia.

[0186] 2. Hemp fiber length: measured by manual grouping weighing method in accordance with GB / T 18147.3-2015.

[0187] 3. Fineness of hemp fiber: measured by mid-section weighing method according to GB / T 18147.4-2015.

[0188] 4. The test method for the decrease in bending stiffness (△G) when the moisture regain of hemp fiber nonwoven fabric increases from 0% to 100% includes the following steps:

[0189] (1) Sample preparation: Take two hemp non-woven fabric samples, one of which is dried at 50°C to a constant weight (mass change rate in 1 hour is less than 1%), which is a hemp fiber non-woven fabric with a moisture regain of 0%; the other is sprayed with water on the surface of the hemp fiber non-woven fabric using a sprayer, combed and placed in a sealed bag for more than 4 hours until the mass is twice the mass of the hemp fiber non-woven fabric with a moisture regain of 0%, that is, a hemp fiber non-woven fabric with a moisture regain of 100%;

[0190] (2) Determine and calculate the mass per unit area of ​​the sample according to GB / T4669;

[0191] (3) Randomly cut 12 specimens with a size of (25±1) mm × (250+1) mm; the long sides of 6 specimens are parallel to the longitudinal direction of the hemp fiber non-woven fabric, and the long sides of 6 specimens are parallel to the transverse direction of the hemp fiber non-woven fabric; the specimens are at least 100 mm away from the edge of the hemp fiber non-woven fabric;

[0192] (4) Place the sample on the platform of the YG207N automatic fabric stiffness tester, with one end of the sample aligning with the front edge of the platform. Place the upper pressing plate on the sample and align them;

[0193] (5) Press the start button and push the specimen forward at a certain speed so that the specimen extends out of the front edge of the platform and bends under its own weight until the extended end of the specimen contacts the inclined surface. Record the extended length of the specimen.

[0194] (6) Take half of the extended length as the bending length, record four bending lengths for each sample, and calculate the average bending length of each sample; calculate the average bending length C of each sample in two directions, in centimeters; calculate the average bending stiffness per unit width in two directions according to formula I, retaining three significant figures;

[0195] Formula I: G = m × C 3 ×10 -3 ;

[0196] Where G is the bending stiffness per unit width, in millinewton centimeters (mN cm); m is the mass per unit area of ​​the sample, in grams per square meter (g / m 2 ); C is the average bending length of the sample, in centimeters (cm);

[0197] (7) The change range is calculated by bending stiffness: the decrease range of bending stiffness △G = (bending stiffness at 0% regain - bending stiffness at 100% regain) / bending stiffness at 0% regain × 100%.

[0198] Comparative Example 4

[0199] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the combing parameters are adjusted through experiments so that the length of the hemp fiber is 15 mm;

[0200] After subsequent preparation, the hemp fibers were too short to be successfully cross-laid, and therefore, hemp non-woven fabrics could not be prepared.

[0201] Comparative Example 5

[0202] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the basis weight of the fiber web in the laying process is 25g / m 2 ;

[0203] After subsequent preparation, the spunlace web was torn due to the low quantitative weight of the fiber web during laying, so the hemp non-woven fabric could not be prepared.

[0204] Comparative Example 6

[0205] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the hydroentanglement process includes two hydroentanglement processes, the hydroentanglement pressure in the first hydroentanglement process is 40 bar, and the hydroentanglement pressure in the second hydroentanglement process is 65 bar;

[0206] After subsequent preparation, the fiber web cannot be completely entangled due to the small number of spunlace processes in the spunlace process, so the hemp non-woven fabric cannot be prepared.

[0207] Comparative Example 7

[0208] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the hydroentanglement process includes four hydroentanglement processes, and the hydroentanglement pressures in the first to fourth hydroentanglement processes are 20 bar, 50 bar, 60 bar, and 75 bar respectively;

[0209] After subsequent preparation, the water spunlace pressure in the water spunlace process was too low, resulting in the inability to completely entangle the fiber web, and thus the hemp non-woven fabric could not be prepared.

[0210] Comparative Example 8

[0211] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the hydroentanglement process includes four hydroentanglement processes, and the hydroentanglement pressures in the first to fourth hydroentanglement processes are 50 bar, 80 bar, 95 bar, and 105 bar, respectively;

[0212] After subsequent preparation, due to the excessively high water spunlace pressure in the water spunlace process, holes appeared in the fiber web, and thus the hemp non-woven fabric could not be prepared.

[0213] Comparative Example 9

[0214] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the hydroentanglement process includes four hydroentanglement processes, and the hydroentanglement pressures in the first to fourth hydroentanglement processes are 40 bar, 80 bar, 95 bar, and 65 bar, respectively;

[0215] After subsequent preparation, due to the large change gradient of the water spunlace pressure in the water spunlace process, holes appeared in the fiber web, and some parts could not be completely entangled, so hemp non-woven fabric could not be prepared.

[0216] Comparative Example 10

[0217] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the hemp fiber nonwoven fabric is first subjected to secondary degumming and then subjected to primary degumming;

[0218] After subsequent preparation, the hemp fiber has a low degree of degumming and a high residual glue rate after the secondary degumming and then the primary degumming treatment, resulting in uneven fiber combing and inability to successfully cross-lay the web, so it is impossible to prepare hemp non-woven fabric.

[0219] Comparative Example 11

[0220] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that in the composite bacteria solution, the mass ratio of alkaliphilic Bacillus to fluorescing Pseudomonas is 1:6;

[0221] After subsequent preparation, due to the bonding force between the prepared hemp fibers, the resistance during the combing process is large, resulting in easy breakage, and the subsequent web cannot be successfully laid, so the hemp non-woven fabric cannot be prepared.

[0222] Comparative Example 12

[0223] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that in the composite bacteria solution, the mass ratio of alkaliphilic Bacillus and fluorescing Pseudomonas is 6:1;

[0224] After subsequent preparation, due to the bonding force between the prepared hemp fibers, the resistance during the combing process is large, resulting in easy breakage, and the subsequent web cannot be successfully laid, so the hemp non-woven fabric cannot be prepared.

[0225] Comparative Example 13

[0226] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that Bacillus subtilis (commonly available in the market, purchased from Beijing Biobo Biotechnology Co., Ltd.) is used to replace the alkaliphilic Bacillus;

[0227] After subsequent preparation, due to the bonding force between the prepared hemp fibers, the resistance during the combing process is large, resulting in easy breakage, and the subsequent web cannot be successfully laid, so the hemp non-woven fabric cannot be prepared.

[0228] Comparative Example 14

[0229] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that Paenibacillus macerans (commonly available in the market, purchased from Beijing Biobo Biotechnology Co., Ltd.) is used to replace Pseudomonas fluorescens;

[0230] After subsequent preparation, due to the bonding force between the prepared hemp fibers, the resistance during the combing process is large, resulting in easy breakage, and the subsequent web cannot be successfully laid, so the hemp non-woven fabric cannot be prepared.

[0231] Comparative Example 15

[0232] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the pH value of the secondary degumming solution is 10, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 7 mL / L;

[0233] After subsequent preparation, the residual rubber rate of the prepared hemp fiber was too high at 30%, resulting in uneven fiber combing and failure to successfully cross-lay the web, so the hemp non-woven fabric could not be prepared.

[0234] Comparative Example 16

[0235] The comparative example of the present invention provides a hemp fiber nonwoven fabric, the only difference between the hemp fiber nonwoven fabric and Example 1 is that the pH value of the secondary degumming solution is 14, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 12 mL / L;

[0236] After subsequent preparation, since the residual rubber rate of the prepared hemp fiber was too low at 3%, the fiber was over-combed and could not be successfully cross-laid, so the hemp non-woven fabric could not be prepared.

[0237] Effect Example 1

[0238] Since the corresponding hemp non-woven fabrics could not be prepared in Comparative Examples 4-16, they were not investigated.

[0239] The properties of the hemp fiber nonwoven fabrics prepared in Examples 1-6 and Comparative Examples 1-3 were tested respectively, specifically the following aspects:

[0240] 1. Breathability

[0241] The test was carried out in accordance with GB / T5453. The test instrument used was YG(B)461D digital fabric air permeability meter; the air permeability was recorded.

[0242] 2. Softness

[0243] According to the testing method of the decrease in flexural rigidity when the moisture regain of hemp fiber non-woven fabric increases from 0% to 100%, the flexural rigidity of hemp fiber non-woven fabric at moisture regain of 0% and moisture regain of 100% was tested respectively.

[0244] 3. Liquid evaporation rate

[0245] Liquids include water and blood, and the test methods are consistent. Blood is commercially available artificial blood, specifically:

[0246] (1) Cut 5 pieces of hemp fiber non-woven fabric, each with a size of 10 cm × 10 cm, mark them and make sure they are flat and wrinkle-free;

[0247] (2) Adjust the humidity of the cut sample to equilibrium under standard atmospheric conditions;

[0248] (3) Weigh the original weight of the sample to an accuracy of 0.001 g;

[0249] (4) Use a pipette to accurately measure 0.2 mL of liquid and gently drop it on the sample, with the pipette tip no more than 1 cm away from the sample surface;

[0250] (5) When the droplet contacts the sample surface and spreads completely, immediately remove it with tweezers and weigh it to an accuracy of 0.001 g;

[0251] (6) After weighing the mass, hang the sample vertically and naturally in a standard atmosphere, and weigh the mass every (1±0.5) min to an accuracy of 0.001 g;

[0252] (7) The test is terminated when the mass change rate between two consecutive weighings does not exceed 1%, and the time when the mass remains unchanged is recorded.

[0253] 4. Antibacterial

[0254] 1) Test method for antibacterial performance of dissolution antibacterial (inhibitory) products: refer to Appendix C4 of GB 15979-2002 for testing; the bacteria used are Staphylococcus aureus ATCC 6538, Escherichia coli 8099, and Candida albicans ATCC 10231; the test is repeated three times, and the antibacterial rates at 2 minutes and 20 minutes are recorded;

[0255] 2) Test method for antibacterial performance of non-dissolving antibacterial (inhibitory) products: refer to Appendix C5 of GB 15979-2002 for testing; the strains used are Staphylococcus aureus ATCC 6538, Escherichia coli 8099, and Candida albicans ATCC 10231; the test is repeated three times, and the average antibacterial rate is recorded; a commercially available pure cotton non-woven fabric is used as a control sample;

[0256] 5. Mildness test

[0257] 1) Skin allergy test:

[0258] (1) Preparation before the test: Cut the hemp fiber non-woven fabric into 2.5×2.5cm 2 The test pieces of different sizes are moistened with physiological saline and used for skin allergy test;

[0259] (2) The test sample group consisted of healthy white guinea pigs with intact skin, 16 in each group. 24 hours before the test, a 3×3 cm 2 The next day, wet the test sample and apply it directly to the left hair removal area, then cover it with a layer of non-irritating plastic film and fix it with non-irritating adhesive tape to induce contact for 6 hours. Repeat the induction in the same way on the 7th and 14th days. On the 28th day, wet the test sample and apply it to the right 3×3cm 2 The hair removal area (hair removal the day before the test) was fixed for 6 hours for stimulation. A negative control group was set up in the test, and the test sample was applied only during the stimulation contact; the positive control group was operated in the same way as the test sample group, with 2,4-dinitrochlorobenzene replacing the test sample, the induction concentration was 1%, and the stimulation concentration was 0.2%. The skin reaction was observed 24 hours and 48 hours after the stimulation contact, and the skin reaction was scored according to Table 2;

[0260] Table 2

[0261]

[0262] According to the standards in Table 2, the number of animals with skin reactions (reaction ≥ 1) was divided by the number of experimental animals in the group to obtain the sensitization rate (%). The sensitization intensity was evaluated according to Table 3. When the sensitization rate was 0%, it was judged that no skin allergic reaction was observed.

[0263] Table 3

[0264] Sensitization rate / % 0-8 9-28 29-64 65-80 81-100 Sensitization intensity Very mild Mild Moderate strength Extreme Strength

[0265] 2) Vaginal mucosal irritation (single):

[0266] (1) Take a hemp fiber nonwoven fabric sample, add sterile saline, and draw the sample liquid after 24 hours for vaginal mucosal irritation test;

[0267] (2) Select healthy female rabbits in early adulthood and divide them into a test group and a control group, with 3 rabbits in each group; use the sample solution as the test sample and saline as the control sample, fix the animal on its back, and expose the perineum and vaginal opening. Wet the catheter and gently insert it into the vagina, and slowly inject 2 mL of the test solution or control page with a syringe, and pull out the catheter to complete the infection. After 24 hours, kill the animal, remove the intact vagina, and observe with the naked eye to see if there are signs of congestion, edema, etc. Fix with 10% formalin solution for 24 hours, select tissue sections from both ends and three central parts of the vagina for histopathological examination, and score the irritation response of the vaginal mucosa according to the provisions of Table 4;

[0268] Table 4

[0269]

[0270] Stimulation back score = A + B + C + D. According to the standard in Table 4, the stimulation response scores of the three parts of the three animals in the test group were added together and then divided by the total number of observations (number of animals × 3) to obtain the average score of the vaginal mucosal irritation response of the test group. The scoring method of the control group was the same as above. The stimulation index was obtained by subtracting the average score of the control group from the average score of the test group, and the stimulation intensity was graded according to Table 5.

[0271] Table 5

[0272] Vaginal mucosal irritation index ＜1 1～＜5 5～＜9 9～＜12 ≥12 Intensity of vaginal mucosal irritation none Very light Mild Moderate Severe

[0273] The results of the above effect test are shown in Table 6-7;

[0274] Table 6

[0275]

[0276] Table 7

[0277]

[0278]

[0279] It can be seen from Example 1 and Comparative Examples 4-16 that the inventors of the present application have solved the current problem that non-woven fabrics cannot be prepared using 100% hemp fiber by exploring a preparation method for non-woven fabrics using 100% hemp fiber as raw materials, and successfully prepared pure hemp fiber non-woven fabrics.

[0280] In addition, it can be seen from Table 6 and Table 7 that the microstructure and parameter index of the hemp fiber non-woven fabric have a significant effect on its air permeability, antibacterial property, softness and liquid evaporation rate. The inventor of the present application studied the microstructure and parameter index of the prepared hemp fiber non-woven fabric, and finally obtained a hemp fiber non-woven fabric with excellent comprehensive performance. Further, it can be seen from Examples 1-6 and Comparative Examples 1-3 that the microscopic pores and bending stiffness changes of the hemp fiber non-woven fabric have a significant effect on its air permeability, antibacterial property, softness and liquid evaporation rate. When the total porosity of the hemp fiber in the hemp fiber non-woven fabric provided by the present invention and the proportion of the porosity of the macropores, mesopores and micropores to the total porosity are within the range given by the present invention, and the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, when the bending stiffness decreases within the range given by the present invention, the obtained hemp fiber non-woven fabric has good air permeability, antibacterial property, softness and liquid evaporation rate. Specifically, the air permeability of the hemp fiber nonwoven fabric obtained in Examples 1-6 is above 621.2 mm / s, the flexural rigidity at a moisture regain of 0% is below 0.860 mN·cm, the flexural rigidity at a moisture regain of 100% is below 0.827 mN·cm, the evaporation time of water is below 30 min, the evaporation time of blood is below 49 min, and no irritation is shown in the irritation test; in terms of antibacterial test, the antibacterial rates of Escherichia coli, Staphylococcus aureus and Candida albicans at 20 min are 87.3-96.4%, 75. The antibacterial rates of the hemp fiber non-woven fabric are between 0-84.6% and 62.4-71.6%, and the antibacterial rates of Escherichia coli, Staphylococcus aureus and Candida albicans in the non-dissolution antibacterial test are between 35-49%, 42-61% and 74-86%, respectively; especially when the total porosity of the hemp fiber and the proportion of the porosity of the macropores, mesopores and micropores in the total porosity are further selected to be within the preferred range given in the present invention, and the moisture regain of the hemp fiber non-woven fabric is increased from 0% to 100%, and the decrease in the flexural rigidity is also within the preferred range given in the present invention, the comprehensive performance of the obtained hemp fiber non-woven fabric is better. Specifically, the air permeability of the hemp fiber nonwoven fabric obtained in Examples 1-3 is above 678.8 mm / s, the flexural rigidity at a moisture regain of 0% is below 0.780 mN·cm, the flexural rigidity at a moisture regain of 100% is below 0.743 mN·cm, the evaporation time of water is below 27 min, the evaporation time of blood is below 45 min, and no irritation is shown in the irritation test; in terms of antibacterial test, the antibacterial rates of Escherichia coli, Staphylococcus aureus and Candida albicans at 20 min in the dissolution antibacterial test are between 92.5-96.4%, 80.7-84.6% and 69.8-71.6%, respectively, and the antibacterial rates of Escherichia coli, Staphylococcus aureus and Candida albicans in the non-dissolution antibacterial test are between 43-49%, 57-61% and 84-86%, respectively;

[0281] It can be seen from Example 1 and Comparative Examples 1-3 that when the total porosity of the hemp fiber used to prepare the hemp fiber non-woven fabric is too low or the proportion of the porosity of macropores, mesopores and small pores in the total porosity is not within the specific range described in the present invention, or when the moisture regain of the hemp fiber non-woven fabric increases from 0% to 100%, the decrease in flexural rigidity is not within the range given in the present invention, the comprehensive performance of the obtained hemp fiber non-woven fabric shows a significant downward trend, especially the antibacterial performance. The total porosity of hemp fiber and the porosity proportions of macropores, mesopores and small pores are different, which not only affects the antibacterial property of the product due to the air permeability of the hemp fiber non-woven fabric, but also affects the distribution and content of the antibacterial groups on the hemp fiber in the hemp fiber non-woven fabric, thereby affecting the antibacterial property of the product. That is, the antibacterial performance of the obtained hemp fiber non-woven fabric is affected by many factors such as the total porosity of the hemp fiber, the proportion of macropores, mesopores and small pores in the hemp fiber, and the distribution and content of the antibacterial groups in the hemp fiber. Therefore, although the total porosity of Comparative Example 3 is within the scope of the present invention, its antibacterial rate was found to be relatively low in actual multiple parallel tests. It is speculated that this is because the proportion of the porosity of macropores, mesopores and small pores in the total porosity changes, resulting in changes in the distribution and content of antibacterial groups on the hemp fiber, thereby affecting the antibacterial properties of the product.

[0282] In addition, the hemp fiber involved in the preparation process of the hemp fiber non-woven fabric in Example 1 was observed by scanning electron microscopy. Specifically, the fiber cross section was cut using a Hastelloy slicer, adhered to the conductive adhesive and dried, and the fiber cross section was observed using a cold field scanning electron microscope. The acceleration voltage of the scanning electron microscope was 10 kV, and the fiber was subjected to gold spraying before cold field scanning electron microscope observation. The observation results were as follows: Figure 3 and Figure 4 As shown; among them, Figure 3 The scanning electron microscope images of the hemp skin obtained after the treatment in step S1 in the preparation process of the hemp fiber in Example 1 at different magnifications are shown in FIG. Figure 3 It can be seen that the proportion of small pores in hemp leather is relatively large, while the proportion of large pores is relatively small; Figure 4 The scanning electron microscope images of the hemp fiber treated in step S4 of Example 1 at different magnifications are shown in FIG. Figure 4 It can be seen that after treatment, the proportion of small pores in hemp fiber is significantly reduced, the proportion of large pores shows an increasing trend, and the porosity of hemp fiber after treatment also shows a significant increasing trend.

[0283] Application Example 1

[0284] The application example of the present invention provides a sanitary napkin, which comprises a sanitary napkin body and wings, wherein the wings are arranged on both sides of the sanitary napkin body, and the sanitary napkin body comprises a surface layer, a wrapping layer, a bottom film and an outer film from top to bottom, wherein an absorbent layer is arranged inside the wrapping layer;

[0285] The surface layer is made of the hemp fiber nonwoven fabric of the present invention

[0286] The photographic picture of the sanitary napkin product is as follows Figure 5 As shown, Figure 5 The middle a is the unfolded photo. Figure 5 Figure b in the middle is a photo of the folded state.

[0287] Application Example 2

[0288] The application example of the present invention provides an adult pull-up pants, the adult pull-up pants include an adult pull-up pants body, the adult pull-up pants body includes a surface layer, an absorbent body and a bottom film from the skin contacting surface downward, the absorbent body includes a first absorbent body and a second absorbent body, and the second absorbent body is located below the first absorbent body; the surface layer is made of the hemp fiber non-woven fabric of the present invention;

[0289] The photographic picture of the adult pull-up pants product is as follows Figure 6 As shown, Figure 6 The middle a is a photo of the outer side. Figure 6 Middle b is a photograph of the inner side.

[0290] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A hemp fiber nonwoven fabric, characterized in that: The hemp fiber nonwoven fabric is composed of hemp fibers; the hemp fibers contain macropores with a pore size greater than 10 μm, mesopores with a pore size of 1-10 μm, and micropores with a pore size less than 1 μm, and the total porosity of the hemp fibers is 30-50%; In the hemp fiber, the porosity of macropores accounts for 48-65% of the total porosity, the porosity of mesopores accounts for 24-50% of the total porosity, and the porosity of micropores accounts for 2-12% of the total porosity; When the moisture regain of the hemp fiber nonwoven fabric increases from 0% to 100%, the bending rigidity decreases by ≥2%.

2. The hemp fiber nonwoven fabric according to claim 1, characterized in that: When the moisture regain of the hemp fiber nonwoven fabric increases from 0% to 100%, the bending rigidity decreases by 3-5%.

3. The hemp fiber nonwoven fabric according to claim 1, characterized in that: The total porosity of the hemp fiber is 36-48%; and / or, in the hemp fiber, the porosity of macropores accounts for 51-60% of the total porosity; and / or, in the hemp fiber, the porosity of the mesopores accounts for 36-44% of the total porosity; And / or, in the hemp fiber, the porosity of small pores accounts for 3-6% of the total porosity.

4. The hemp fiber nonwoven fabric according to claim 1, characterized in that: The hemp fiber has a fineness of >2000Nm and a length of >28mm.

5. The hemp fiber nonwoven fabric according to claim 4, characterized in that: The hemp fiber has a fineness of 2240-2600 Nm and a length of 28.3-35 mm.

6. The method for preparing the hemp fiber nonwoven fabric according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: S1. Break and beat the hemp stalks after rain and dew to obtain hemp skins; S2, degumming the hemp skin using a composite bacterial solution, wherein the composite bacterial solution contains alkaliphilic Bacillus and Pseudomonas fluorescens in a mass ratio of 1:(1-2); S3, placing the hemp fiber after the primary degumming in step S2 in a secondary degumming solution for secondary degumming to obtain degummed hemp fiber; the pH value of the secondary degumming solution is 12-13.5, and the volume concentration of hydrogen peroxide in the secondary degumming solution is 9-10 mL / L; S4, soaking the degummed hemp fiber in oil, and then deoiling and dehydrating it for humidification and curing; wherein the relative humidity of the humidification and curing treatment is 60-70%, and the temperature is ≥25°C; S5, opening and combing the hemp fiber after the humidification and curing treatment to obtain hemp fiber with a length of more than 28 mm and a residual rubber rate of 5-20%; S6. The hemp fiber is cleaned, combed and laid to obtain a fiber web; wherein the weight of the fiber web is ≥33g / m 2 ; S7. The fiber web is subjected to a spunlace process and a spunlace post-process in sequence to obtain a hemp fiber non-woven fabric; wherein the spunlace process includes four spunlace processes, and the spunlace pressures in the first to fourth spunlace processes are 35-45 bar, 60-70 bar, 75-85 bar, and 85-95 bar, respectively.

7. The preparation method according to claim 6, characterized in that: The concentration of bacteria in the composite bacteria solution is (0.1-10)×10 -8 CFU / mL; and / or, the solid-to-liquid ratio of a degumming is 1 g: (5-15) mL; And / or, the primary degumming temperature is 32-36° C. and the time is 6-8 h.

8. The preparation method according to claim 6, characterized in that: The solid-liquid ratio of the secondary degumming is 1g: (8-12)mL; And / or, the temperature of the secondary degumming is 98-100° C., and the time of the secondary degumming is 60-120 min.

9. Use of the hemp fiber nonwoven fabric according to any one of claims 1 to 5 in the preparation of sanitary products.

10. The use according to claim 9, characterized in that: The sanitary products include any one of sanitary napkins, panty liners, band-aids, diapers, adult pull-up pants, and disposable underwear.

11. A sanitary napkin, characterized in that: The surface layer of the sanitary napkin is the hemp fiber nonwoven fabric as described in any one of claims 1 to 5.

12. The sanitary napkin according to claim 11, characterized in that The sanitary napkin further comprises an absorbent layer and a backing layer.

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