Modified flax fiber and its preparation and application

Abstract

The present invention belongs to the technical field of fiber material preparation and specifically discloses a modified flax fiber, its preparation, and application. The modified flax fiber is prepared by treating flax fiber with liquid ammonia, soaking it in lubricating oil, mixing it with a polyurethane resin, and then heat-curing it. The surface of the modified flax fiber is coated with an oil film. The modified flax fiber of the present invention is durable and fluffy, has high dimensional stability, good shrinkage and wrinkle resistance, high softness, good elasticity, and good hygroscopicity. The preparation method of the modified flax fiber is simple to operate, easy to control, low in cost, and suitable for industrial production. The preparation process can avoid recrystallization of cellulose III. The prepared modified flax fiber has excellent performance and is conducive to the development of high-end flax.

Description

Technical Field

[0001] The present application relates to the technical field of fiber material preparation, and in particular to a modified flax fiber and its preparation and application. Background Art

[0002] Flax fiber is a natural cellulosic fiber composed of a variety of chemical substances, including cellulose, lignin, pectin, hemicellulose, nitrogen-containing substances, fatty waxes, and ash. Its fibers are coarse, rigid, and free of natural curl. Due to its unique internal structure, flax fabrics possess excellent properties such as moisture absorption, breathability, mildew and antibacterial properties, smoothness, and comfort. This makes it an ideal fabric for men's and women's uniforms, jackets, and casual wear, and a natural, environmentally friendly fabric ideal for the new century. Furthermore, its simple, elegant style and health benefits have made it a popular choice among consumers. Currently, flax is widely used in the production of home textiles. The flax product range is diversifying, extending beyond yarn, cloth, and mats to include a wide range of products, including pillows, bedspreads, curtains, tablecloths, cushions, neck pillows, and tapestries. Home textiles made from flax are not only easy to clean but also offer a unique style.

[0003] Flax fiber has the advantages of excellent moisture absorption, low static electricity, strong warmth retention, corrosion resistance and heat resistance. However, flax fiber also has defects such as hardness, easy wrinkling, shrinkage, difficulty in spinning, weaving and dyeing, which leads to its poor wearing performance and is not easy to be made into high-end textile flax fiber.

[0004] To address this situation, a variety of modification methods have been developed, including physical, chemical, and biological modification. Physical modification methods primarily include discharge technology, high-pressure steam flash explosion, ultrasonic cavitation, microwave irradiation, and liquid ammonia processing. Chemical modification methods primarily include cellulose ester modification, cellulose ether modification, cellulose grafting, and cellulose crosslinking.

[0005] Currently, the main methods for modifying flax fibers that have achieved industrial production both domestically and internationally include liquid ammonia processing and alkali mercerization. Liquid ammonia modification and alkali mercerization have similar effects. Existing research shows that caustic soda mercerization can eliminate pre-treatment creases and improve the dyeing depth and brilliance of linen fabrics. Liquid ammonia treatment can also improve the fabric's wearability, including wrinkle recovery angle, dimensional stability, and wrinkle-free index. However, residual alkali from alkali mercerization is difficult to remove and can lead to fiber erosion and unevenness. The key difference is that liquid ammonia modification is superior to alkali mercerization.

[0006] Liquid ammonia treatment decrystallizes flax and alters the cellulose crystal structure, transforming cellulose I into cellulose III, reducing crystallinity and increasing amorphous regions. However, this change is reversible, as cellulose III is unstable. Washing to remove the ammonia causes recrystallization of cellulose III, which in turn transforms into cellulose I. Liquid ammonia swells the fibers, forming hydrogen-bonded complexes. The nitrogen atoms in ammonia, due to their unshared electron pairs, react with hydroxyl groups in cellulose, replacing OH-O with OH-N, forming a swelled complex. This complex decomposes when the ammonia is removed with water. When the liquid ammonia reagent is removed, cellulose I undergoes lattice changes. Flax cellulose is a natural polymer with a crystalline structure. The characteristics of the crystals impart microscopic order, meaning that the spatial arrangement of the structural units has a three-dimensional, long-range, ordered lattice structure. After liquid ammonia treatment, the crystallinity and other diffraction properties of flax fibers undergo significant changes, with decreased crystallinity, increased amorphous regions, and the transformation of cellulose I into the low-temperature variant cellulose III. After deammonification with hot water, cellulose III is largely converted back to cellulose I, restoring its crystallinity to its initial state. This, in turn, reduces the softness, hygroscopicity, and dye adsorption properties of the liquid ammonia-modified flax fiber. Therefore, in the liquid ammonia modification process for flax fiber, removing residual liquid ammonia from the fiber is a crucial step, as it determines the performance of the modified fiber.

[0007] Existing research provides a method for crystallization modification of flax fibers. The flax fibers are placed in a sealed container, filled with a modifying medium, and pressurized to the modification pressure. The pressure is then instantaneously released and the modifying medium removed to obtain crystallization-modified flax fibers. This method, employing the above technical solutions, offers the following advantages: 1. Modification is achieved by altering the lattice structure. The modified fibers overcome their original defects, resulting in increased porosity, reduced crystallinity, and improved fiber softness, thus enhancing the product's dimensional stability, softness, and dyeing properties. 2. The instantaneous release of pressure maximizes the expansion of the modified fibers, significantly increasing their bulk and softness, thereby significantly improving their spinning, weaving, and dyeing properties. This method removes liquid ammonia from the flax fibers by evaporating them through simultaneous heating and vacuuming, preventing recrystallization of cellulose III. However, this method requires controlling the flow rate, time, and temperature of the ammonia solution during the filling process, as well as controlling the pressure increase and pressure reduction time. This modification method is difficult to control, and different pressure increase rates are required for flax fibers of different deniers and lengths, making it less universal. The pressure increase rate must be calculated for each modification, making the process cumbersome.

[0008] Therefore, if a modified flax fiber and a preparation method can be provided, which can reduce the fiber crystallinity without damaging the fiber, avoid adverse conditions such as cellulose III recrystallization, and obtain better dimensional stability, anti-shrinkage and anti-wrinkle, good durability and other effects, and the preparation method is simple and easy to control, it will be more conducive to the development of flax fiber in the textile field. Summary of the Invention

[0009] In view of the above-mentioned shortcomings of the prior art, the present invention provides a modified flax fiber and its preparation and application, so as to solve the problems existing in the prior art, such as high crystallinity of flax fiber, resulting in poor fabric feel, itchy feeling, poor dimensional stability and poor wrinkle resistance; easy recrystallization after liquid ammonia treatment; and complex modification method and difficulty in control.

[0010] To achieve the above and related objects, the present invention provides a first aspect of a modified flax fiber. The modified flax fiber is prepared by treating flax fiber with liquid ammonia, soaking it in lubricating oil, mixing it with a polyurethane resin, and then heating and curing it. The surface of the modified flax fiber is coated with an oil film.

[0011] In one embodiment of the present application, the lubricating oil includes silicone oil and hydrocarbon lubricating oil.

[0012] A second aspect of the present invention provides a method for preparing modified flax fiber, the method comprising the following steps:

[0013] (1) Liquid ammonia treatment: the pre-dried flax fibers are placed in liquid ammonia for padding;

[0014] (2) Adsorption treatment: mixing the lubricating oil with the flax fibers treated with liquid ammonia in step (1), and allowing the mixture to stand to allow the lubricating oil to be adsorbed on the flax fibers treated with liquid ammonia, thereby obtaining oil-containing flax fibers;

[0015] (3) Film formation: mixing the oil-containing flax fiber in step (2) with the polyurethane resin, heating, and keeping the temperature constant to obtain modified flax fiber with an oil film coated on the surface.

[0016] Based on the above technical means, the present invention reduces the moisture content of the flax fibers by pre-drying them, preventing uneven moisture content in the fibers and thereby improving the liquid ammonia treatment effect. The present invention vaporizes and dries the liquid ammonia in the flax fibers at high temperatures, removing the liquid ammonia as a mixture of steam and ammonia, achieving the purpose of liquid ammonia treatment while avoiding the need for hot water to remove ammonia and preventing recrystallization of cellulose III.

[0017] In one embodiment of the present application, the lubricating oil in step (2) includes silicone oil and hydrocarbon lubricating oil.

[0018] In one embodiment of the present application, in step (2), the mass ratio of the lubricating oil to the flax fibers treated with liquid ammonia is (5-15):(1-2); and the standing time is 15-30 minutes.

[0019] In one embodiment of the present application, the mass ratio of the oil-containing flax fiber to the polyurethane resin in step (3) is (1-2):(5-10).

[0020] In one embodiment of the present application, the heating rate in step (3) is 3-8°C / min, and the temperature is heated to 80-100°C.

[0021] In one embodiment of the present application, the holding time in step (3) is 20 to 50 minutes.

[0022] In one embodiment of the present application, the flax fibers are pre-dried in step (1) and then air-cooled.

[0023] According to the above technical means, the present invention can quickly cool the high-temperature flax fibers through air cooling, so that when the flax fibers are immersed in liquid ammonia, the temperature is lower, thereby achieving a better liquid ammonia treatment effect.

[0024] A third aspect of the present invention provides a use of the modified flax fiber as described above or the modified flax fiber prepared by the method for preparing the modified flax fiber as described above in single yarn or fabric.

[0025] The beneficial technical effects of the present invention are:

[0026] Flax fiber has streaks and cracks on its microscopic surface and high crystallinity, which makes its fabric have poor gloss, poor feel, and an itchy feeling, making it difficult to meet consumer requirements and also restricting the development of high-end flax.

[0027] The present invention first pre-dries the flax fibers to reduce their moisture content, then air-cools them after drying to quickly cool the high-temperature flax fibers so that when they are placed in liquid ammonia, the temperature is lower, thereby achieving a better liquid ammonia treatment effect. The present invention uses liquid ammonia to padded the flax fibers, allowing ammonia molecules to penetrate into the flax fiber fibrils in a very short time, swelling the fibers, reducing the pores between the base fibrils or microfibrils within the fibers, promoting the cross-linking of transverse hydrogen bonds between microfibril units, increasing the elasticity of the fiber material, reducing crystallinity, and increasing the amorphous region of the flax fibers, thereby improving the dye uptake, softness, and emollient properties of the flax fibers.

[0028] The present invention involves immersing flax fibers treated with liquid ammonia in lubricating oil, separating the solid and liquid to obtain oil-containing flax fibers. A thermo-reactive waterborne polyurethane resin is then mixed with the oil-containing flax fibers for thermal curing, spreading a lubricating oil film of a certain thickness on the flax fiber surface. The thermo-reactive waterborne polyurethane resin is commonly used as a textile finishing agent, exhibiting good film-forming properties and elasticity, and can impart wrinkle resistance to fabrics. Its primary uses include wrinkle prevention, shrinkage prevention, dimensional stability, and stretch processing for linen fabrics. It can react with aminosilicone oil and other additives to form a three-dimensional polymer film on the fibers, which can impart various long-lasting finishing properties to the fibers, such as excellent softness, fullness, washability, wear resistance, smoothness, and a pleasant hand feel. The polyurethane resin can be used to manufacture household textiles such as clothing, raincoats, tents, quilts, and pillowcases. Therefore, the present invention utilizes a polyurethane resin to react with the oil-containing flax fibers to impart a variety of finishing properties to the flax fibers. In addition, the present invention avoids using hot water to remove ammonia, and instead uses heating evaporation to remove ammonia, thereby preventing the ammonia-cellulose composite from being converted back into cellulose I. During the thermal curing process, the residual liquid ammonia in the oil-containing flax fiber evaporates, thereby achieving the purpose of simultaneously removing the residual liquid ammonia. In addition, no recrystallization of cellulose III occurs during the deammoniation process, and the performance of the modified flax fiber can be maintained.

[0029] Furthermore, the oil-containing flax fiber of the present invention can construct a network structure within the polyurethane resin, improving its compressive properties and helping to reduce interfacial deformation. Simultaneously, due to the polyurethane resin's sealing effect on the fiber, the lubricating oil is securely locked within the resin matrix, resulting in a good oil retention rate, thereby maintaining the performance of the modified flax fiber. Furthermore, the oil film applied to the flax fiber after liquid ammonia mercerization further enhances the fiber's softness. Furthermore, the polyurethane resin, acting as a film-forming agent, can further regulate the flax fiber's properties, such as its fullness and wrinkle resistance. Furthermore, the isolating effect of the oil film ensures that the various finishing properties of the modified flax fiber of the present invention are durable, maintaining good performance even after repeated washings.

[0030] In summary, the modified flax fiber of the present invention is durable and fluffy, has high dimensional stability, good shrinkage and wrinkle resistance, high softness, and good elasticity and moisture absorption. The modified flax fiber of the present invention can improve the rough feel and itchy feeling of linen fabrics, enhance overall softness, and improve wearing comfort.

[0031] The modified flax fiber preparation method of the present invention is simple to operate, easy to control, low in cost, and suitable for industrial production. Recrystallization of cellulose III can be avoided during the preparation process. The prepared modified flax fiber has excellent performance and is conducive to the development of high-end flax. DETAILED DESCRIPTION

[0032] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention pertains. It should be understood that certain features of the present invention (described in the context of separate embodiments for clarity) may also be provided in combination in a single embodiment. On the contrary, a plurality of features of the present invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or in any other described embodiment of the present invention when appropriate. Certain features described in the context of various embodiments will not be considered as essential features of those embodiments unless the embodiment is inoperable without those elements. The present invention will be further described below by specific examples, but it should be noted that the specific process conditions and results described in the embodiments of the present invention are only used to illustrate the present invention and cannot limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and substance of the present invention should be included within the scope of protection of the present invention.

[0033] The present invention provides a method for preparing modified flax fiber, which comprises the following steps:

[0034] (1) Liquid ammonia treatment: The flax fibers are preliminarily dried through a drying drum, and the pre-dried flax fibers are cooled by a blower. After cooling, the fibers are placed in liquid ammonia and padded for 1 to 5 minutes.

[0035] (2) Adsorption treatment: mixing lubricating oil with the flax fibers treated with liquid ammonia in step (1), and allowing the mixture to stand at room temperature for 15 to 30 minutes to allow the lubricating oil to be adsorbed on the flax fibers treated with liquid ammonia, thereby obtaining oil-containing flax fibers; wherein the lubricating oil comprises silicone oil and hydrocarbon lubricating oil, and the mass ratio of the lubricating oil to the flax fibers treated with liquid ammonia is (5 to 15):(1 to 2);

[0036] (3) Film formation: mixing the oil-containing flax fiber in step (2) with the polyurethane resin, heating, and keeping the temperature for 20 to 50 minutes to obtain a modified flax fiber with an oil film coated on the surface, wherein the mass ratio of the oil-containing flax fiber to the polyurethane resin is (1 to 2): (5 to 10), and heating to 80 to 100° C. at a heating rate of 3 to 8° C. / min.

[0037] The present invention also provides a modified flax fiber, which is prepared by treating flax fiber with liquid ammonia, soaking it in lubricating oil, mixing it with a polyurethane resin, and then heating and curing it. The surface of the modified flax fiber is coated with an oil film. The lubricating oil includes silicone oil and hydrocarbon lubricating oil.

[0038] The present invention also provides the use of the modified flax fiber as described above or the modified flax fiber prepared by the preparation method of the modified flax fiber as described above in single yarn or fabric.

[0039] The present invention is described in detail below by way of specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not to be limited to the specific numerical values exemplified below.

[0040] Example 1

[0041] (1) Liquid ammonia treatment: The flax fibers were preliminarily dried by a drying drum, and the pre-dried flax fibers were cooled by a blower. After cooling, the fibers were placed in liquid ammonia and padded for 1.5 min.

[0042] (2) Adsorption treatment: silicone oil and the flax fibers treated with liquid ammonia in step (1) are mixed at a mass ratio of 5:1, and the mixture is allowed to stand at room temperature for 20 minutes to allow the lubricating oil to be adsorbed on the flax fibers treated with liquid ammonia, thereby obtaining oil-containing flax fibers;

[0043] (3) Film formation: The oil-containing flax fiber in step (2) is mixed with the polyurethane resin in a mass ratio of 1:5, heated to 80°C at a heating rate of 5°C / min, and kept warm for 30 minutes to obtain a modified flax fiber with an oil film coated on the surface.

[0044] Example 2

[0045] (1) Liquid ammonia treatment: The flax fibers are preliminarily dried through a drying drum, and the pre-dried flax fibers are cooled by a blower. After cooling, the fibers are placed in liquid ammonia and padded for 1 minute.

[0046] (2) Adsorption treatment: silicone oil and the flax fibers treated with liquid ammonia in step (1) are mixed at a mass ratio of 6:1, and the mixture is allowed to stand at room temperature for 25 minutes to allow the lubricating oil to be adsorbed on the flax fibers treated with liquid ammonia, thereby obtaining oil-containing flax fibers;

[0047] (3) Film formation: The oil-containing flax fiber in step (2) is mixed with the polyurethane resin in a mass ratio of 1:6, heated to 90°C at a heating rate of 5°C / min, and kept warm for 30 minutes to obtain a modified flax fiber with an oil film coated on the surface.

[0048] Example 3

[0049] (1) Liquid ammonia treatment: The flax fibers were preliminarily dried by a drying drum, and the pre-dried flax fibers were cooled by a blower. After cooling, the fibers were placed in liquid ammonia and padded for 1.5 min.

[0050] (2) Adsorption treatment: amino silicone oil and the flax fiber treated with liquid ammonia in step (1) are mixed at a mass ratio of 5:1, and the mixture is allowed to stand at room temperature for 20 minutes to allow the lubricating oil to be adsorbed on the flax fiber treated with liquid ammonia, thereby obtaining oil-containing flax fiber;

[0051] (3) Film formation: The oil-containing flax fiber in step (2) is mixed with the polyurethane resin in a mass ratio of 1:5, heated to 80°C at a heating rate of 5°C / min, and kept warm for 30 minutes to obtain a modified flax fiber with an oil film coated on the surface.

[0052] Example 4

[0053] (1) Liquid ammonia treatment: The flax fibers are preliminarily dried through a drying drum, and the pre-dried flax fibers are cooled by a blower. After cooling, the fibers are placed in liquid ammonia and padded for 2 minutes.

[0054] (2) Adsorption treatment: silicone oil and the flax fiber treated with liquid ammonia in step (1) are mixed in a mass ratio of 8:1, and the mixture is allowed to stand at room temperature for 30 minutes to allow the lubricating oil to be adsorbed on the flax fiber treated with liquid ammonia, thereby obtaining oil-containing flax fiber;

[0055] (3) Film formation: The oil-containing flax fiber in step (2) is mixed with the polyurethane resin in a mass ratio of 1:5, heated to 100°C at a heating rate of 8°C / min, and kept warm for 30 minutes to obtain a modified flax fiber with an oil film coated on the surface.

[0056] Comparative Example 1

[0057] The flax fiber was placed in liquid ammonia for 1.5 minutes, washed with hot water at 70°C for 5 minutes, washed twice, washed with warm water, neutralized with 1g / L hydrochloric acid for 5 minutes, washed thoroughly with water until neutral, and dried to obtain modified flax fiber.

[0058] Comparative Example 2

[0059] The flax fibers are preliminarily dried by a drying drum, and the pre-dried flax fibers are cooled by a fan, and then placed in liquid ammonia for padding for 1.5 minutes.

[0060] The flax fiber treated with liquid ammonia was mixed with a polyurethane resin in a mass ratio of 1:5, magnesium chloride and aluminum nitrate were added as synergistic catalysts, the mass concentration of the polyurethane resin was 100 g / L, and the mass concentration of the catalyst was 15 g / L. The mixture was baked at 160°C for 3 min to obtain modified flax fiber.

[0061] Performance Testing

[0062] Wrinkle Resistance: Fabrics made from the modified flax fibers prepared in Examples 1-4 and Comparative Examples 1-2 were used as test samples. The wrinkle recovery angles of the fabrics were measured after 20 washes, and the wrinkle recovery angles were calculated. The test results are shown in Table 1.

[0063] Softness: Fabrics made from the modified flax fibers prepared in Examples 1-4 and Comparative Examples 1-2 were used as test samples. The softness (SF) of the test samples prepared in Examples 1-4 and Comparative Examples 1-2 was rated according to AATCC 202-2014, the relative hand value of textiles. The rating results are shown in Table 2.

[0064] Oil Content: The modified flax fibers prepared in Examples 1-4 were tested for oil content. The test method involved using a high-speed centrifuge to measure the difference in mass before and after weighing. The oil-spinning speed was 3000 rpm, and the test lasted 30 minutes. The sample was weighed and the change in oil content was calculated. The test results are shown in Table 3.

[0065] Crystallinity: The modified flax fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested for fiber crystallinity using wide-angle X-ray diffraction, and the decrease in crystallinity compared to the unmodified flax fibers was calculated. The test results are shown in Table 4.

[0066] Table 1 Wrinkle resistance test results of modified flax fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0067] Initial wrinkle recovery angle Wrinkle recovery angle after washing 20 times Example 1 263° 255° Example 2 266° 257° Example 3 271° 263° Example 4 259° 250° Comparative Example 1 231° 209° Comparative Example 2 251° 231°

[0068] As shown in Table 1, the modified flax fibers prepared by the present invention exhibited wrinkle recovery angles greater than 250° after 20 washes, demonstrating superior wrinkle resistance compared to Comparative Examples 1 and 2. The wrinkle recovery angle of the modified flax fibers prepared by the present invention did not significantly decrease after 20 washes, with the maximum reduction rate being 3.47%. This is because the present invention, on the one hand, increases the wrinkle recovery angle of the flax fibers through liquid ammonia treatment, and on the other hand, further increases the wrinkle recovery angle through wrinkle-resistant finishing by polyurethane resin treatment. The reduction rates for Comparative Example 1 and Comparative Example 2 were 9.5% and 7.9%, respectively. The modified flax fibers in Comparative Example 2 do not contain an oil film, lacking the barrier properties of the oil film. Consequently, their wrinkle resistance is relatively reduced.

[0069] Table 2 Softness test results of modified flax fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0070]

[0071]

[0072] (Note: The higher the grade, the softer the fabric.)

[0073] As shown in Table 2, the modified flax fibers prepared by the preparation method of the present invention all achieved a softness rating of Grade 7, significantly improving their softness compared to Comparative Examples 1 and 2. This is because the softness of the modified flax fibers of the present invention is affected by three factors: first, the effect of liquid ammonia improves softness; second, the effect of lubricants such as silicone oil enhances the compliance of the flax fibers, softening the fiber bundles and improving their hand feel; and third, the softening effect of the polyurethane resin further adjusts the fullness and softness of the flax fibers. Consequently, due to these combined effects, the modified flax fibers of the present invention possess excellent softness. Furthermore, the oil film allows the modified flax fibers of the present invention to maintain a full, soft hand even after multiple washes.

[0074] Table 3 Test results of oil content of modified flax fibers prepared in Examples 1 to 4

[0075] Oil content (%) Oil retention rate (%) Example 1 13.42 100 Example 2 12.78 100 Example 3 13.43 100 Example 4 12.62 100

[0076] As shown in Table 3, the modified flax fibers prepared according to the present invention have good oil content and oil retention, due to the lubricating oil being securely locked in the polyurethane resin. Under the action of the oil film, the modified flax fibers according to the present invention exhibit durable finishing properties, increasing fiber bundle density, reducing hairiness, improving weaving efficiency and quality, enhancing suppleness, enhancing hand feel, and providing antistatic properties.

[0077] Table 4 Test results of crystallinity reduction rate of modified flax fibers prepared in Examples 1 to 4 and Comparative Examples 1 to 2

[0078] Crystallinity reduction rate (%) Example 1 25％ Example 2 22％ Example 3 25％ Example 4 21％ Comparative Example 1 11％ Comparative Example 2 18％

[0079] As shown in Table 4, the crystallinity of the modified flax fiber prepared in the present invention is significantly lower than that of the unmodified flax fiber. Therefore, the modified flax fiber of the present invention exhibits improved softness and wrinkle resistance. The preparation method of the present invention effectively prevents recrystallization of cellulose III during the deammoniation treatment.

[0080] In summary, the modified flax fiber of the present invention has good shrinkage and wrinkle resistance and high softness. It can also improve the rough feel and irritation of linen fabrics, enhance overall softness, and improve wearing comfort. The method for preparing the modified flax fiber of the present invention is simple to operate, easy to control, and low-cost, making it suitable for industrial production. The prepared modified flax fiber has excellent performance and durability.

[0081] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing modified flax fiber, characterized in that: The method comprises the following steps: (1) Liquid ammonia treatment: the pre-dried flax fibers are placed in liquid ammonia for padding; (2) Adsorption treatment: mixing the lubricating oil with the flax fibers treated with liquid ammonia in step (1), and allowing the mixture to stand for 15 to 30 minutes to allow the lubricating oil to be adsorbed on the flax fibers treated with liquid ammonia, thereby obtaining oil-containing flax fibers. The mass ratio of the lubricating oil to the flax fibers treated with liquid ammonia is (5 to 15):(1 to 2), and the lubricating oil includes silicone oil and hydrocarbon lubricating oil. (3) Film formation: the oil-containing flax fiber in step (2) is mixed with the polyurethane resin, heated, and kept warm to obtain modified flax fiber with an oil film coated on the surface.

2. The method for preparing modified flax fiber according to claim 1, characterized in that: In the step (3), the mass ratio of the oil-containing flax fiber to the polyurethane resin is (1-2): (5-10).

3. The method for preparing modified flax fiber according to claim 1, characterized in that: The heating rate in step (3) is 3-8°C / min, and the temperature is heated to 80-100°C.

4. The method for preparing modified flax fiber according to claim 1, characterized in that: The holding time in step (3) is 20 to 50 minutes.

5. The method for preparing modified flax fiber according to claim 1, characterized in that: In the step (1), the flax fibers are pre-dried and then air-cooled.

6. A modified flax fiber obtained by the method according to any one of claims 1 to 5, characterized in that: The modified flax fiber is prepared by treating flax fiber with liquid ammonia, soaking it in lubricating oil, mixing it with polyurethane resin, and heating and curing it. The surface of the modified flax fiber is covered with an oil film, and the lubricating oil includes silicone oil and hydrocarbon lubricating oil.

7. Use of the modified flax fiber prepared by the method according to any one of claims 1 to 5 in single yarn or fabric.

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