Technological method for degumming flax fibers through combination of ultrasonic waves and compound enzymes

Abstract

The invention relates to a process method for degumming jute fibers through combination of ultrasonic waves and compound enzyme. The process method comprises the following steps: (1) carrying out ultrasonic treatment on pretreated jute fibers; (2) performing compound enzyme degumming treatment on the flax fibers subjected to ultrasonic treatment; and (3) bleaching the degummed flax fibers in a low-alkali-hydrogen peroxide system. The method can effectively utilize waste to extract natural fibers, is beneficial to environment protection and saves resources; moreover, the damage to the fiber quality is small, the degumming efficiency is high, and the obtained jute fiber can meet the spinning requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of flax degumming, and particularly relates to a process for degumming flax fiber by combining ultrasound and complex enzyme. Background Art

[0002] Sesame is an oil flax, a herbaceous plant of the genus Linum in the family Linaceae. Sesame stalks are rich in bast tissue, and sufficient sesame fibers can be separated. As a natural plant fiber, sesame fiber fabrics and clothing have the characteristics of rapid moisture absorption and heat dissipation, good air permeability, antibacterial and mildew-proof, antistatic, anti-allergic, and excellent strength and modulus. It is a free-breathing textile. At present, sesame fiber is interwoven with wool to form a plain weave product with a double warp and single weft structure, which makes the cloth surface light, smooth, flat and strong. It is a new way to achieve lightness and coolness of wool fabrics, and has unlimited market potential. Sesame fiber is located in the bast tissue of sesame stalks and is a bundle of plant fibers. Its basic chemical component is cellulose. Other non-fibrous substances such as pectin, hemicellulose, lignin, and fat wax are all associated with cellulose, which affects the deep processing of sesame fiber and greatly limits the application of sesame fiber. Therefore, to extract the usable fiber, its colloid must be degummed, separated, and impurity-removed. The quality of the degumming process directly affects the structure, mechanical properties and availability of the fiber, and is a key link in hemp fiber processing.

[0003] Enzymatic degumming utilizes the synergistic effect of extracellular proteins obtained through separation and purification, including degrading enzymes such as pectinase and hemicellulose, to degrade the external colloid of the fiber, relax the cell structure, and promote the effective combination of degrading enzymes with other polymers, thereby improving the overall degumming efficiency of sesame fiber.

[0004] Ultrasonic waves are a high-frequency mechanical energy with a frequency higher than 20kHz, and their functions are multifaceted. Ultrasonic waves are compressed and expanded when they move in liquid media. The resulting mechanical effects and fluid dynamic cavitation phenomena (the formation, expansion and rupture of many tiny steam bubbles) can increase the permeability of solvents to plant cells, increase the contact area between hydrated ions in the solution and sesame fibers, accelerate the diffusion rate of hydrated ions, increase the activity frequency of the puffing zone of the colloid complex, promote the emulsification, homogenization and suspension of the colloid complex, shorten the degumming time of sesame fibers, accelerate the reaction process, thereby improving the extraction efficiency of fibers and reducing damage to sesame fibers.

[0005] The sesame bast fiber is processed by physical degumming, chemical degumming, biological degumming and combined degumming to make the sesame fiber meet the requirements of spinnability. There are few studies on sesame fiber at home and abroad, and they are still limited to the basic degumming methods, with problems such as incomplete degumming, rough fiber surface and poor fiber color. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a process for degumming flax fibers, so as to shorten the degumming time, thereby improving the degumming efficiency of the flax fibers and preparing the flax fibers that can be used for textile processing.

[0007] The present invention provides a process for ultrasonic-compound enzyme combined degumming flax fiber, comprising the following steps:

[0008] (1) subjecting the pretreated flax fiber to ultrasonic treatment, and then drying;

[0009] (2) placing the ultrasonically treated sesame fiber in an enzyme solution with a bath ratio of 1:10 to 1:50 and a total amount of complex enzyme of 4% to 12% (owf), adjusting the solution pH to 3.0 to 6.0, treating at 30 to 70° C. for 4 to 14 hours, and then washing with water;

[0010] (3) The degummed sesame fiber is placed in a low-alkali-hydrogen peroxide boiling and bleaching solution at a temperature of 70 to 90° C. for 60 to 80 minutes, and then washed and dried.

[0011] Preferably, the pretreatment method of sesame fiber in step (1) is: cutting dry original stems with intact bast into sesame stem segments with a length of 10 cm, peeling off the sesame bast, and making single sesame fibers weighing 1 g.

[0012] Preferably, the specific process of ultrasonic treatment in step (1) is as follows: after adding distilled water at a bath ratio of 1:25 to 1:40, the pretreated sesame fiber is placed in an ultrasonic processor with a set frequency of 25 to 50 kHz, a power of 110 to 130 W, and a temperature of 50 to 90° C. for 60 to 100 minutes, and then placed in an oven at 60 to 70° C. and dried to a constant mass for standby use.

[0013] Preferably, the complex enzyme in step (2) comprises at least two biological enzymes selected from the group consisting of xylanase, β-mannanase, pectinase and laccase.

[0014] More preferably, the complex enzyme comprises xylanase, β-mannanase and pectinase.

[0015] Preferably, in step (2), citric acid-sodium citrate buffer is used to adjust the pH.

[0016] Preferably, the low-alkali-hydrogen peroxide bleaching liquid in step (3) contains 3% H2O2, 3.0 g / L NaOH, 3.0 g / L sodium silicate, 1.0 g / L scouring agent JFC, 4 g / L tetraacetylethylenediamine, and the bath ratio is 1:30 to 1:50.

[0017] Beneficial Effects

[0018] (1) The method of the present invention can effectively utilize waste to extract natural fibers, which is beneficial to protecting the environment and saving resources;

[0019] (2) The method of the present invention has mild reaction conditions, environmentally friendly operation, little damage to fiber quality, and high degumming efficiency;

[0020] (3) After degumming by the method of the present invention, flax fibers with a low residual glue rate and a small diameter are obtained, which can meet the spinning requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The cross-sectional morphology of the flax fiber obtained in Example 1 of the present invention at different magnifications: (a) 100 times fiber morphology, (b) 400 times fiber morphology, (c) 1000 times fiber morphology, and (d) longitudinal structural morphology.

[0022] Figure 2 The SEM images and electron microscope images of the present invention are (a) undegummed flax fiber, (b) flax fiber degummed by composite enzyme in comparative example 1, and (c) flax fiber degummed by ultrasound-composite enzyme in example 1. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0024] The present invention provides a process for ultrasonic-compound enzyme combined degumming flax fiber, comprising the following steps:

[0025] (1) After adding distilled water at a bath ratio of 1:25 to 1:40, the pretreated sesame fiber is placed in an ultrasonic processor with a set frequency of 25 to 50 kHz, a power of 110 to 130 W, and a temperature of 50 to 90° C. for 60 to 100 minutes, and then placed in an oven at 60 to 70° C. to dry to a constant mass for later use;

[0026] (2) placing the ultrasonically treated sesame fiber in an enzyme solution with a bath ratio of 1:10 to 1:50 and a total amount of complex enzyme of 4% to 12% (owf), adjusting the solution pH to 3.0 to 6.0, treating at 30 to 70° C. for 4 to 14 hours, and then washing with water;

[0027] (3) The degummed sesame fiber is placed in a low-alkali-hydrogen peroxide boiling and bleaching solution at a temperature of 70 to 90° C. for 60 to 80 minutes, and then washed and dried.

[0028] The pretreatment method of sesame fiber in the embodiment of the present invention is: select dry original stems with complete bast, cut off the stem segments with a length of about 10 cm, peel the sesame bast manually, and make single sesame fibers weighing about 1 g in the uniformly mixed sesame bast.

[0029] The method of the present invention utilizes the "cavitation effect" of the ultrasonic state. Under the impact of the kinetic energy of the ultrasonic wave, the colloid layer on the fiber surface is destroyed, and the colloid is gradually broken into small groups, which are then peeled off, and the residual glue rate of the fiber decreases. Subsequently, the fiber is soaked in a biological enzyme solution. The degumming enzyme system is at an optimal pH value, the enzyme activity is enhanced, the enzyme molecules are adsorbed on the surface of the fiber, and the binding groups of the active center are complexed with the substrate to form an enzyme-substrate complex. Due to the instability of the complex, enzyme molecules and soluble products will be formed. At the same time, in the degumming reaction, the enzyme cuts the α-1,4 glycosidic bonds of the long-chain substances (pentose, hexose) to generate small molecules soluble in water, thereby achieving the purpose of degumming and completing clean production. The sesame fiber treated by this process has a colloid removal rate of 75% to 85%.

[0030] The flax fibers obtained in the embodiments and comparative examples were tested and characterized:

[0031] The K / S value and whiteness of flax fiber under different degumming processes were determined using a computer colorimeter (Color i 5D, Datacolor, USA).

[0032] The YG(B)002 fiber fineness comprehensive analyzer was used to measure the average diameter of flax fiber, and the morphology of flax fiber under optical microscope before and after degumming was recorded.

[0033] The breaking strength of flax fiber was tested by YG001 single fiber electronic strength tester, and the breaking strength changes of flax fiber under different treatment conditions were analyzed.

[0034] The chemical structure changes of flax fiber after undegummed, bioenzyme-treated and chemical degummed were tested by total reflectance method using IR affinity-1 Fourier transform infrared spectrometer.

[0035] The surface morphology of flax fiber before and after degumming was examined using a TM 4000Plus scanning electron microscope.

[0036] The fiber sample powder was subjected to XRD test using a Rigaku Smart Lab SE X-ray diffractometer with Cu as target;

[0037] The XPS analysis of the fiber samples before and after degumming was carried out using an ESCALAB 250Xi X-ray photoelectron spectrometer.

[0038] Example 1

[0039] The process of degummed flax fiber in this embodiment comprises the following steps:

[0040] (1) The pretreated flax fiber was treated in an ultrasonic processor at a frequency of 40 kHz, a power of 120 W, and a temperature of 80° C. for 80 min, and then placed in a 65° C. oven to a constant mass for later use;

[0041] (2) placing the ultrasonically treated sesame fiber in an enzyme solution (containing 4.4% xylanase, 2.3% β-mannanase and 1.3% pectinase by weight) with a bath ratio of 1:30 and a composite enzyme dosage of 8% (owf), adjusting the pH to 5 with citric acid-sodium citrate buffer, treating at a temperature of 60°C for 4 hours, and then washing with water;

[0042] (3) The degummed sesame fiber is placed in a bleaching solution containing 3% H2O2, 3.0 g / L NaOH, 3.0 g / L sodium silicate, 1.0 g / L scouring agent JFC, 4 g / L tetraacetylethylenediamine, and a bath ratio of 1:40, and treated at a temperature of 80°C for 70 minutes, followed by water washing and drying.

[0043] The obtained sesame fiber had a residual rubber rate of 14.49%, a whiteness of 63.53, a breaking strength of 44.56 cN, and an average diameter of 14.21 μm.

[0044] Figure 1 The cross-sectional morphology of the flax fiber obtained in Example 1 at different magnifications: (a) 100 times fiber morphology, (b) 400 times fiber morphology, (c) 1000 times fiber morphology, and (d) longitudinal structural morphology.

[0045] Example 2

[0046] The process of degummed flax fiber in this embodiment comprises the following steps:

[0047] (1) The pretreated flax fiber was treated in an ultrasonic processor at a frequency of 40 kHz, a power of 120 W, and a temperature of 90° C. for 80 min, and then placed in a 65° C. oven to a constant mass for later use;

[0048] (2) placing the ultrasonically treated sesame fiber in an enzyme solution (containing 4.4% xylanase, 2.3% β-mannanase and 1.3% pectinase by weight) with a bath ratio of 1:30 and a composite enzyme dosage of 8% (owf), adjusting the pH to 6 with citric acid-sodium citrate buffer, treating at a temperature of 70°C for 8 hours, and then washing with water;

[0049] (3) The degummed sesame fiber is placed in a bleaching solution containing 3% H2O2, 3.0 g / L NaOH, 3.0 g / L sodium silicate, 1.0 g / L scouring agent JFC, 4 g / L tetraacetylethylenediamine, and a bath ratio of 1:40, and treated at a temperature of 80°C for 70 minutes, followed by water washing and drying.

[0050] The obtained sesame fiber had a residual rubber rate of 16.95%, a whiteness of 53.53, a breaking strength of 46.34 cN, and an average diameter of 16.11 μm.

[0051] Example 3

[0052] The process of degummed flax fiber in this embodiment comprises the following steps:

[0053] (1) The pretreated flax fiber was treated in an ultrasonic processor at a frequency of 40 kHz, a power of 120 W, and a temperature of 80° C. for 80 min, and then placed in a 65° C. oven to a constant mass for later use;

[0054] (2) placing the ultrasonically treated sesame fiber in an enzyme solution (containing 5.4% xylanase, 2.8% β-mannanase and 1.8% pectinase by weight) with a bath ratio of 1:20 and a composite enzyme dosage of 10% (owf), adjusting the pH to 5 with citric acid-sodium citrate buffer, treating at a temperature of 60°C for 6 hours, and then washing with water;

[0055] (3) The degummed sesame fiber is placed in a bleaching solution containing 3% H2O2, 3.0 g / L NaOH, 3.0 g / L sodium silicate, 1.0 g / L scouring agent JFC, 4 g / L tetraacetylethylenediamine, and a bath ratio of 1:40, and treated at a temperature of 80°C for 70 minutes, followed by water washing and drying.

[0056] The obtained sesame fiber had a residual rubber rate of 16.32%, a whiteness of 52.88, a breaking strength of 48.64 cN and an average diameter of 17.33 μm.

[0057] Example 4

[0058] The process of degummed flax fiber in this embodiment comprises the following steps:

[0059] (1) The pretreated flax fiber was treated in an ultrasonic processor at a frequency of 40 kHz, a power of 120 W, and a temperature of 80° C. for 90 min, and then placed in a 65° C. oven to a constant mass for later use;

[0060] (2) placing the ultrasonically treated flax fiber in an enzyme solution (containing 6.4% xylanase, 3.3% β-mannanase and 2.3% pectinase by weight) with a bath ratio of 1:40 and a composite enzyme dosage of 12% (owf), adjusting the pH to 5 with citric acid-sodium citrate buffer, treating at a temperature of 60°C for 8 hours, and then washing with water;

[0061] (3) The degummed sesame fiber is placed in a bleaching solution containing 3% H2O2, 3.0 g / L NaOH, 3.0 g / L sodium silicate, 1.0 g / L scouring agent JFC, 4 g / L tetraacetylethylenediamine, and a bath ratio of 1:40, and treated at a temperature of 80°C for 70 minutes, followed by water washing and drying.

[0062] The obtained sesame fiber had a residual rubber rate of 18.14%, a whiteness of 51.04, a breaking strength of 42.33 cN, and an average diameter of 18.71 μm.

[0063] Comparative Example 1

[0064] Degumming was performed using an enzyme solution with a composite enzyme dosage of 8% (owf) (containing 4.4% xylanase, 2.3% β-mannanase and 1.3% pectinase by weight), and the resulting sesame fiber had a residual glue rate of 18.23%, a whiteness of 62.89, a breaking strength of 43.36 cN and an average diameter of 17.22 μm.

[0065] Figure 2 The SEM pictures and electron microscope pictures (a) are sesame fibers without degumming, (b) are sesame fibers degummed by composite enzyme in comparative example 1, and (c) are sesame fibers degummed by combined ultrasonic-composite enzyme in example 1. It can be seen that the sesame fibers obtained by combined ultrasonic-composite enzyme degumming have a low residual glue rate and a small average diameter, and can better meet the spinning requirements.

[0066] Comparative Example 2

[0067] The sesame fiber degummed by xylanase had a residual rubber rate of 19.27%, a whiteness of 61.32, a breaking strength of 41.69 cN and an average diameter of 18.18 μm.

[0068] The sesame fiber degummed by β-mannanase had a residual gum rate of 21.98%, a whiteness of 60.66, a breaking strength of 43.92 cN and an average diameter of 18.66 μm.

[0069] The sesame fiber degummed by pectinase had a residual gum rate of 23.60%, a whiteness of 59.32, a breaking strength of 42.82 cN and an average diameter of 18.89 μm.

[0070] When degumming with a single biological enzyme, the residual glue rate of the sesame fiber obtained is relatively high.

Claims

1. A process for degumming flax fiber by ultrasonic-compound enzyme, comprising the following steps: (1) subjecting the pretreated flax fiber to ultrasonic treatment, and then drying; (2) placing the ultrasonically treated sesame fiber in an enzyme solution with a bath ratio of 1:10 to 1:50 and a total amount of complex enzyme of 4% to 12% (owf), adjusting the solution pH to 3.0 to 6.0, treating at 30 to 70° C. for 4 to 14 hours, and then washing with water; (3) The degummed sesame fiber is placed in a low-alkali-hydrogen peroxide boiling and bleaching solution at a temperature of 70 to 90° C. for 60 to 80 minutes, and then washed and dried.

2. The process according to claim 1, characterized in that: The pretreatment method of sesame fiber in step (1) is as follows: cutting the dry original stem with intact bast into sesame stem segments with a length of 10 cm, peeling the sesame bast, and making single sesame fibers weighing 1 g.

3. The process according to claim 1, characterized in that: The specific process of ultrasonic treatment in step (1) is as follows: after adding distilled water at a bath ratio of 1:25 to 1:40, the pretreated sesame fiber is placed in an ultrasonic processor with a set frequency of 25 to 50 kHz, a power of 110 to 130 W, and a temperature of 50 to 90° C. for 60 to 100 minutes, and then placed in an oven at 60 to 70° C. and dried to a constant mass for later use.

4. The process according to claim 1, characterized in that: The complex enzyme in step (2) comprises at least two biological enzymes selected from the group consisting of xylanase, β-mannanase, pectinase and laccase.

5. The process according to claim 4, characterized in that: The complex enzyme comprises xylanase, beta mannanase and pectinase.

6. The process according to claim 1, characterized in that: In the step (2), citric acid-sodium citrate buffer is used to adjust the pH.

7. The process according to claim 1, characterized in that: In the step (3), the low alkali-hydrogen peroxide bleaching liquid contains 3% H2O2, 3.0g / L NaOH, 3.0g / L sodium silicate, 1.0g / L scouring agent JFC, 4g / L tetraacetylethylenediamine, and the bath ratio is 1:30-1:50.

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