CN110452402A - A kind of method that Mechanical Method prepares hydrophobic high permeable fiber film - Google Patents

Abstract

The invention discloses a method for mechanically preparing a hydrophobic and highly air-permeable fiber membrane, which belongs to the field of biomass green fiber materials and environmental protection materials. In the invention, the cellulose raw material is sequentially subjected to enzymatic hydrolysis pretreatment, mechanical grinding, forming and drying steps to finally obtain a hydrophobic and highly air-permeable fiber membrane. The cellulose film prepared by the method of the present invention has a compact structure, excellent mechanical properties, high transparency, strong hydrophobicity, an average water contact angle of up to 106°, and an air permeability of up to 75.77s/(in ² ·100cc·1.22KPa); No chemicals are used in the preparation process of the invented cellulose membrane, no complex chemical reaction process is required, no complicated process and high equipment investment are required; the water contact angle of the obtained cellulose membrane can reach 106°, which has good water resistance , can be used in high humidity environment.

Description

A method for mechanically preparing hydrophobic and highly air-permeable fiber membranes

technical field

The invention belongs to the field of green fiber materials and environment-friendly micro-nano materials, in particular to a method for mechanically preparing hydrophobic and highly air-permeable fiber membranes.

Background technique

Cellulose is the most abundant biopolymer on earth, and it is mainly found in the cell walls of higher plants. Micro-nano cellulose not only has the advantages of wide source of raw materials, high strength, large specific surface area, good biocompatibility, biodegradability, renewable recycling, etc. Tens of microns scale, small diameter, large aspect ratio, and excellent mechanical properties. These remarkable properties make it possible to make transparent micro-nanocellulose film paper for high-end fields such as packaging, high-temperature-resistant flexible electronic component substrates, and microfluidic chips.

However, the surface of nanocellulose contains a large number of functional groups - hydroxyl groups, which are very easy to absorb water, resulting in high water absorption of transparent nanopaper, which limits the direct application in packaging, electronic devices, microfluidic chips and other fields.

At present, there are a large number of hydrophilic groups on the surface of the cellulose nanomembrane prepared by common methods. The cellulose membrane material is usually sensitive to humidity and has poor water tolerance. After absorbing moisture, the cellulose membrane will swell and deform and reduce its strength. and poor barrier properties. In addition, when preparing composite materials, hydrophilic cellulose also has the problem of poor compatibility with other hydrophobic matrices. A large number of literatures have been reported on the hydrophobic modification of nanocellulose, and physical adsorption and chemical modification are commonly used methods. Physical surface adsorption is mainly achieved by adsorbing surfactants, electrically opposite substances or polymer electrolytes on the surface of CNF through the action of water affinity, electrostatic attraction, hydrogen bond or van der Waals force. Chemical modification is to introduce various small molecules or macromolecules on the surface of cellulose through covalent linkage. However, these treatment methods generally require heating or long treatment time, and sometimes need to add some toxic chemical reagents, and the treatment efficiency is not high, making it difficult to scale production.

In summary, there are still many problems in the research process of the hydrophobicity of cellulose membranes, and there are still many problems in the process of cellulose microfibrillation that hinder its large-scale production and application, such as: long pretreatment cycle, not environmentally friendly, chemical Drugs are expensive, difficult to recycle, and have high preparation costs. In addition, cellulose nanomembranes prepared by traditional methods have poor water resistance and are not easy to use in humid environments. Complicated, costly or environmentally unfriendly subsequent treatments are required for hydrophobic modification. Therefore, there is an urgent need to develop an efficient, sustainable, low-cost, and environmentally friendly method to prepare high-performance cellulose membranes. Therefore, the present invention proposes a method for mechanically preparing hydrophobic and highly air-permeable fiber membranes to overcome the above-mentioned problems, realize green, energy-saving, and environmentally friendly production processes, and make new materials widely used in packaging, microfluidic chips, and high-temperature-resistant flexible electronics. High-end fields such as component substrates.

The information disclosed in this Background section is only for enhancing the understanding of the general background of the present invention and should not be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

Contents of the invention

Aiming at the above-mentioned deficiencies existing in the prior art, the object of the present invention is to prepare a kind of hydrophobic and highly air-permeable fiber membrane with a simple process, which solves the high energy consumption, high cost, and inability to mass-produce the technology prepared by the existing method. question.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A method for mechanically preparing a hydrophobic and highly air-permeable fiber membrane, comprising the following steps:

(1) Enzymolysis pretreatment: the cellulose raw material is subjected to enzymolysis pretreatment with cellulase under the condition of heating in a water bath to obtain a slurry;

(2) Mechanical grinding: After rinsing the slurry obtained in step (1), use a high-concentration disc refiner to perform mechanical grinding on the cellulose to microfibrillate the cellulose and realize the formation of the amorphous region of the cellulose. Destruction, partial dissolution of cellulose surface molecules and dissolution of hemicelluloses to obtain micro/nano cellulose suspensions;

(3) Molding and drying: the micron/nanocellulose suspension obtained in step (2) is molded by casting method, and the hydrophobic and highly air-permeable fiber membrane is obtained after drying.

Preferably, the cellulose raw material in step (1) is bagasse, cotton, wheat straw, reed, mulberry bark or jute; and the cellulose raw material is dispersed and pretreated with a cellulose decomposing machine at 40,000 rpm.

Preferably, the cellulase pretreatment conditions in step (1) are: enzymolysis time is 30 minutes, and enzymolysis temperature is 50°C.

As preferably, when adopting high-concentration disc mill to process cellulose suspension in step (2), the distance between the discs of high-concentration disc mill is 0.01-0.07mm; the cellulose content in the cellulose suspension is 5-30wt% ; Grinding frequency is 5-30 times.

As preferably, the micron/nanocellulose suspension obtained in step (2) is subjected to ultrasonic treatment and magnetic stirring treatment before the tape casting method described in step (3); the magnetic stirring speed is 600rpm; the micron/nanofiber The quantitative value of the plain suspension is 15g/cm ² .

As a preference, the drying treatment in step (3) is carried out in a blast drying oven.

Preferably, the drying temperature of the blast drying oven is 35-45°C.

Compared with prior art, the beneficial effect of the present invention is:

The cellulose film prepared by the present invention has excellent properties, compact structure, high strength, high transparency, good hydrophobicity, and air permeability as high as 75.77s/(in2.100cc.1.22KPa); and the cellulose film of the present invention has not undergone any hydrophobic Modification treatment does not require complicated chemical reactions, expensive chemical reagents and equipment, and molecular rearrangement and recrystallization can occur on the cellulose surface during mechanical treatment and film formation; the water contact angle of the obtained nanocellulose film Up to 106°, can be used in high humidity environment.

Description of drawings

Fig. 1 is the picture of the hydrophobic angle of the hydrophobic highly air-permeable cellulose film obtained in Example 1;

Fig. 2 is the scanning electron microscope picture of the obtained hydrophobic highly air-permeable cellulose film in embodiment 1;

Fig. 3 is the picture of the hydrophobic angle of the hydrophobic highly air-permeable cellulose film obtained in Example 2;

Fig. 4 is the scanning electron microscope picture of the obtained hydrophobic highly air-permeable cellulose film in embodiment 2;

Fig. 5 is the picture of the hydrophobic angle of the hydrophobic highly air-permeable cellulose film obtained in Example 3;

6 is a scanning electron microscope picture of the hydrophobic and highly air-permeable cellulose membrane obtained in Example 3.

Detailed ways

The present invention will be more readily understood with reference to the following examples, which are given without limiting the scope of the invention.

Example 1

(1) Disperse and pretreat the bagasse slurry with a cellulose decomposing machine at 40,000 rpm. After decomposing, use cellulase to perform enzymatic hydrolysis for 30 minutes under the condition of heating in a water bath at 50° C.;

(2) Rinse the enzymatically hydrolyzed cellulose slurry with a large amount of distilled water, remove the enzyme liquid, and use a high-concentration disc mill to grind the cellulose mechanically. The distance between the discs of the high-concentration disc mill is 0.07. mm; the cellulose content in the cellulose suspension is 30 wt%; the number of grinding times is 20 times. Grinding makes cellulose microfibrillation and achieves the destruction of the amorphous region of cellulose, the partial dissolution of cellulose surface molecules and the dissolution of hemicellulose to obtain a micro/nano cellulose suspension;

(3) The micron/nano cellulose suspension is subjected to magnetic stirring treatment, the magnetic stirring speed is 600rpm, and the micron/nano cellulose suspension is quantitatively 15g/cm ² is molded by tape casting, and dried in a blast drying oven treatment, the drying temperature is 35° C., and the hydrophobic and highly air-permeable fiber membrane can be obtained after drying.

Example 2

(1) Disperse and pretreat the bagasse slurry with a cellulose decomposing machine at 40,000 rpm. After decomposing, use cellulase to perform enzymatic hydrolysis for 30 minutes under the condition of heating in a water bath at 50° C.;

(2) Rinse the enzymatically hydrolyzed cellulose slurry with a large amount of distilled water, remove the enzyme liquid, and use a high-concentration disc mill to grind the cellulose mechanically. The distance between the discs of the high-concentration disc mill is 0.07. mm; the cellulose content in the cellulose suspension is 30 wt%; the number of grinding times is 25 times. Grinding makes cellulose microfibrillation and achieves the destruction of the amorphous region of cellulose, the partial dissolution of cellulose surface molecules and the dissolution of hemicellulose to obtain a micro/nano cellulose suspension;

(3) The micron/nano cellulose suspension is subjected to magnetic stirring treatment, the magnetic stirring speed is 600rpm, and the micron/nano cellulose suspension is quantitatively 15g/cm ² is molded by tape casting, and dried in a blast drying oven treatment, the drying temperature is 35° C., and the hydrophobic and highly air-permeable fiber membrane can be obtained after drying.

Example 3

(1) Disperse and pretreat the bagasse slurry with a cellulose decomposing machine at 40,000 rpm. After decomposing, use cellulase to perform enzymatic hydrolysis for 30 minutes under the condition of heating in a water bath at 50° C.;

(2) Rinse the enzymatically hydrolyzed cellulose slurry with a large amount of distilled water, remove the enzyme liquid, and use a high-concentration disc mill to grind the cellulose mechanically. The distance between the discs of the high-concentration disc mill is 0.07. mm; the cellulose content in the cellulose suspension is 30 wt%; the number of grinding times is 30 times. Grinding makes cellulose microfibrillation and achieves the destruction of the amorphous region of cellulose, the partial dissolution of cellulose surface molecules and the dissolution of hemicellulose to obtain a micro/nano cellulose suspension;

(3) The micron/nano cellulose suspension is subjected to magnetic stirring treatment, the magnetic stirring speed is 600rpm, and the micron/nano cellulose suspension is quantitatively 15g/cm ² is molded by tape casting, and dried in a blast drying oven treatment, the drying temperature is 35° C., and the hydrophobic and highly air-permeable fiber membrane can be obtained after drying.

performance testing test

The thickness, elastic modulus, folding endurance, contact angle and air permeability of the cellulose films obtained in Examples 1-3 of the present invention were tested respectively, and the test results are shown in Table 1 below.

Table 1 The performance test of the cellulose film obtained in Examples 1-3 of the present invention

As can be seen from Table 1, the cellulose film prepared by the present invention has excellent properties, compact structure, high strength, high transparency, good hydrophobicity, and air permeability as high as 75.77s/(in2.100cc.1.22KPa).

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to make and use various exemplary embodiments of the invention, as well as various Choose and change. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (7)

1. A method for mechanically preparing hydrophobic and highly air-permeable fiber membranes, characterized in that, may further comprise the steps: (1) Enzymolysis pretreatment: the cellulose raw material is subjected to enzymolysis pretreatment with cellulase under the condition of heating in a water bath to obtain a slurry; (2) Mechanical grinding: After rinsing the slurry obtained in step (1), use a high-concentration disc refiner to perform disc grinding mechanical grinding on the cellulose to microfibrillate the cellulose and destroy the amorphous region of the cellulose , Partial dissolution of cellulose surface molecules and dissolution of hemicellulose to obtain micro/nano cellulose suspension; (3) Molding and drying: the micron/nanocellulose suspension obtained in step (2) is molded by casting method, and the hydrophobic and highly air-permeable fiber membrane is obtained after drying. 2. mechanical method according to claim 1 prepares the method for hydrophobic highly air-permeable fiber membrane, it is characterized in that, the cellulose raw material described in step (1) is bagasse, cotton, wheat straw, reed, mulberry bark or jute; The above-mentioned cellulose raw material adopts the 40000rpm of cellulose unwinding machine to carry out dispersion pretreatment. 3. The method for mechanically preparing a hydrophobic and highly air-permeable fiber membrane according to claim 1, wherein the cellulase pretreatment conditions described in step (1) are: enzymolysis time is 30min, and enzymolysis temperature is 50°C . 4. mechanical method according to claim 1 prepares the method for hydrophobic highly air-permeable fiber film, it is characterized in that, when adopting high-concentration disc mill to process cellulose suspension in step (2), between the high-concentration disc mill grinding discs The pitch of the cellulose is 0.01-0.07mm; the cellulose content in the cellulose suspension is 5-30wt%; the grinding frequency is 5-30 times. 5. mechanical method according to claim 1 prepares the method for hydrophobic highly air-permeable fiber membrane, it is characterized in that, step (2) gained micron/nanometer cellulose suspension is carried out before casting method molding described in step (3). Ultrasonic treatment and magnetic stirring treatment; the rotational speed of the magnetic stirring is 600 rpm; the quantitative value of the micro/nano cellulose suspension is 15 g/cm ² . 6. The method for mechanically preparing hydrophobic and highly air-permeable fiber membranes according to claim 1, characterized in that, the drying treatment in step (3) is carried out in a blast drying oven. 7 . The method for mechanically preparing a hydrophobic and highly air-permeable fiber membrane according to claim 6 , wherein the drying temperature of the blast drying oven is 35-45° C.