阅读说明：本技术 可调控亲疏水性纳米纤维素薄膜、及其制备方法和应用 (Controllable hydrophilic and hydrophobic nano cellulose film, and preparation method and application thereof ) 是由 蒋兴宇 查瑞涛 张春亮 于 2018-06-07 设计创作，主要内容包括：本发明提供了一种可调控亲疏水性纳米纤维素薄膜,还提供了该纳米纤维素薄膜的制备方法和应用。所述纳米纤维素薄膜采用纳米纤维素、聚合物、施胶剂、施胶促进剂制备。本发明所制备的可调控亲疏水性的纳米纤维素薄膜具有高的疏水接触角,高的阻隔水和氧的能力,稳定性好,适印性好。本发明采用红外二次加热和加入施胶剂的方法,提高了纳米纤维素膜施胶度。本发明制备薄膜的方法简单易行,操作方便,制备周期短；采用工业上成熟的流延法,可以大规模生产可调控亲疏水性纳米纤维素薄膜。(The invention provides a nano cellulose film with adjustable hydrophilicity and hydrophobicity, and also provides a preparation method and application of the nano cellulose film. The nano-cellulose film is prepared from nano-cellulose, a polymer, a sizing agent and a sizing promoter. The nano cellulose film with adjustable hydrophilicity and hydrophobicity prepared by the invention has high hydrophobic contact angle, high water and oxygen barrier capability, good stability and good printability. The invention adopts the method of infrared secondary heating and adding sizing agent, thus improving the sizing degree of the nano cellulose membrane. The method for preparing the film is simple and easy to implement, convenient to operate and short in preparation period; the industrially mature tape casting method is adopted, and the nano cellulose film with adjustable hydrophilicity and hydrophobicity can be produced in a large scale.)

1. The nano-cellulose film with adjustable hydrophilicity and hydrophobicity is characterized in that the nano-cellulose film is prepared from nano-cellulose, a polymer, a sizing agent and a sizing promoter.

2. The nanocellulose film of claim 1, wherein the nanocellulose is selected from one or more of: nanocrystalline cellulose, microfibrillated cellulose, nanofibrillated cellulose, and their respective modified products;

Preferably, the modified product is selected from one or more of the following: nanocrystaline cellulose, microfibrillated cellulose, cationized, carboxymethylated, carboxylated and hydroxypropylmethylated products of nanofibrillated cellulose.

3. The nanocellulose film of claim 2, wherein said cationized modified product has a degree of substitution of 0.03 to 0.2, carboxymethylated modified product has a degree of substitution of 0.05 to 0.4, carboxylated modified product has a degree of substitution of 0.05 to 0.4, and hydroxypropyl methylated modified product has a degree of substitution of 0.05 to 0.6.

4. the nanocellulose film of any of claims 1 to 3, wherein the polymer is selected from one or more of: guar gum, gelatin, carrageenan, gellan gum, locust bean gum, furcellaran, cellulose gum or soy protein.

5. The nanocellulose film of any of claims 1 to 4, characterized in that the sizing agent is selected from one or more of the following: alkenyl succinic anhydride, alkyl ketene dimer.

6. The nanocellulose film of any of claims 1 to 5, wherein the sizing accelerator is selected from one or more of: polydiallyl dimethyl ammonium chloride, cationic polyacrylamide, polyethyleneimine, polyvinylamine and chitosan.

7. The method of any one of claims 1 to 6, wherein the method is an in-slurry hydrophobization method comprising the steps of:

(1) Adding the nano-cellulose dispersion liquid into the polymer solution, uniformly mixing, adding a sizing agent and a sizing promoter in the continuous stirring process, and uniformly mixing to obtain mixed slurry;

(2) And (2) pouring the mixed slurry obtained in the step (1) into a casting machine to cast a membrane, and drying to obtain the nano cellulose membrane.

8. The method for preparing a nanocellulose film according to any of claims 1 to 6, characterized in that it is a surface hydrophobization method comprising the steps of:

(1) Adding the nano-cellulose dispersion liquid into the polymer solution, and uniformly mixing to obtain mixed slurry;

(2) Pouring the mixed slurry obtained in the step (1) into a casting machine to carry out casting film making to obtain a nano cellulose/polymer composite film;

(3) And (3) coating a sizing agent and a sizing accelerator on the surface of the nano-cellulose/polymer composite film obtained in the step (2), and performing secondary drying to obtain the nano-cellulose film.

9. the method for preparing a nanocellulose film according to claim 7 or 8, characterized in that said nanocellulose: polymer (b): sizing agent: the mass ratio of the sizing accelerator is 100-500: 24-100: 0.04-0.08: 0.0001 to 0.004; the mass fraction of the nano-cellulose in the nano-cellulose dispersion liquid is 2%; the mass fraction of the polymer in the polymer solution is 2%; the nano cellulose dispersion liquid and the polymer solution are both aqueous solutions;

Preferably, the conditions for cast film formation are: the speed of the casting machine is 0.1-0.5 m/min; the temperature of the heating plate is adjusted to be 60-90 ℃, and the knife edge gap is 300-450 mu m; the drying method is infrared drying.

10. Use of the nanocellulose film of any one of claims 1 to 6 or prepared by the method of any one of claims 7 to 9 for the preparation of packaging materials, solar cell substrate materials, photovoltaic devices and/or flexible circuits.

Technical Field

The invention belongs to the field of material science, and particularly relates to a nano cellulose film with adjustable hydrophilicity and hydrophobicity, and a preparation method and application thereof.

Background

Cellophane, a commercially regenerated cellulose film that can replace polypropylene and polyethylene, has found wide use in food packaging, printing paper, linered paper, decorative packaging, and the like. A large amount of carbon disulfide is used in the process of sulfonating and ortho-formation in the production process of the cellophane, a large amount of carbon disulfide is generated in the process of solidification in an acid bath, a series of byproducts such as hydrogen sulfide, sulfur dioxide, sulfuric acid mist and the like exist, meanwhile, the post-treatment process of waste gas is expensive, secondary pollution exists, and therefore the worldwide cellophane yield is always about 10 ten thousand tons per year in recent decades, and the market potential demand is very large. It is necessary to develop a low-pollution, green and environment-friendly regenerated cellulose film production technology.

Nanocellulose has the properties of large aspect ratio, high crystallinity, low density and high strength. The film prepared from the nano-cellulose has high strength, high transparency, high thermal stability and high gas barrier property, and can be widely used as packaging materials, solar cell substrate materials, photoelectric devices, flexible circuits and the like.

The nano cellulose molecular structure contains a plurality of active hydroxyl groups, so that the nano cellulose is endowed with high hydrophilicity, and the nano cellulose film prepared by carrying out vacuum filtration or room-temperature natural evaporation on the nano cellulose dispersion liquid has moisture sensitivity in practical application, so that the nano cellulose is easy to swell after absorbing water, the strength and the rigidity are reduced, the permeation of water and air is accelerated, the application of the nano cellulose film in a high-humidity environment is limited, and the large-scale production is difficult to realize.

the chemical modification of the nanocellulose can effectively improve the hydrophobic capacity of the cellulose, and comprises esterification, carbonylation, etherification, polymer grafting modification and the like. In the prior art, a superhydrophobic nano cellulose membrane is prepared by modifying a nano cellulose membrane with perfluoroalkyl thiol, but the nano cellulose membrane only realizes surface hydrophobization and is assisted by a mesoporous silicon nano network coated on the surface. In the prior art, a series of operations such as organoalkoxysilane, waterborne fluorocarbon resin and corresponding curing agent are used to obtain modified nanocellulose, and a vacuum filtration method is used to obtain the hydrophobized nanocellulose membrane, but the operation is complex and the period is long. The key step of preparing the hydrophobic substance by preparing the hydrophobic substance containing the organoalkoxysilane and then preparing the super-hydrophobic oleophobic transparent nano-cellulose paper by a suction filtration-hot pressing method in the prior art is the preparation of the hydrophobic substance, but the hydrophobic substance is added into the cellulose dispersion liquid by simple mixing, the long-term stability of the nano-cellulose paper is to be further determined, and the large-scale production has certain limitation. In the prior art, a water-resistant regenerated nano cellulose film can be prepared by adopting a method combining a mechanical method and a chemical method, and the hydrophobic modification of the cellulose film is realized by spraying an ethanol solution of polymethyltriethoxysilane on the surface, but only the surface hydrophobic modification is involved, and the stability of a hydrophobic coating is required to be further improved.

Although the existing chemical modification can realize the control of the hydrophobicity of the nano cellulose membrane, the defects of long reaction time, heating and catalyst requirement, low efficiency, difficulty in large-scale production and the like generally exist, and the method is far away from industrial production.

The problem to be solved at present is to find a nano cellulose film which is convenient and rapid, can be produced in a large scale and can regulate and control the hydrophilic and hydrophobic capacity.

in the papermaking process, the sizing agent is used to improve the water resistance of the cellulose membrane and improve the water resistance of the cellulose membrane. Compared with the traditional sizing method, the nano-cellulose has high specific surface area and contains a large amount of hydroxyl, so that the contact area between the nano-cellulose and the sizing agent can be effectively increased, the sizing effect can be increased, and the prepared hydrophobic nano-cellulose film has a large application space.

Disclosure of Invention

Therefore, the invention aims to overcome the defects in the prior art and provide the nano cellulose film with controllable hydrophilicity and hydrophobicity, and the preparation method and the application thereof.

Before the technical solution of the present invention is explained, the terms used herein are defined as follows:

The term "ASA" means: alkenyl succinic anhydrides.

the term "AKD" refers to: an alkyl ketene dimer.

in order to achieve the above purpose, the first aspect of the present invention provides a controllable hydrophilic and hydrophobic nanocellulose film, which is prepared by using nanocellulose, a polymer, a sizing agent and a sizing accelerator.

the nanocellulose film according to the first aspect of the invention, wherein the nanocellulose is selected from one or more of: nanocrystalline cellulose, microfibrillated cellulose, nanofibrillated cellulose and their respective modified products;

Preferably, the modified product is selected from one or more of the following: nanocrystaline cellulose, microfibrillated cellulose, cationized, carboxymethylated, carboxylated and hydroxypropylmethylated products of nanofibrillated cellulose.

more preferably, the degree of substitution of the cationized modified product is 0.03-0.2, the degree of substitution of the carboxymethylated modified product is 0.05-0.4, the degree of substitution of the carboxylated modified product is 0.05-0.4, and the degree of substitution of the hydroxypropyl methylated modified product is 0.05-0.6.

the nanocellulose film according to the first aspect of the invention, wherein said polymer is selected from one or more of: guar gum, gelatin, carrageenan, gellan gum, locust bean gum, furcellaran, cellulose gum or soy protein.

the nanocellulose film according to the first aspect of the invention, wherein said sizing agent is selected from one or more of the following: alkenyl succinic anhydride, alkyl ketene dimer.

the nanocellulose film according to the first aspect of the invention, wherein said sizing promoter is selected from one or more of the following: polydiallyl dimethyl ammonium chloride, cationic polyacrylamide, polyethyleneimine, polyvinylamine and chitosan.

the second aspect of the present invention provides the method for preparing the nanocellulose film described in the first aspect, which is an in-slurry hydrophobization method, comprising the steps of:

(1) adding the nano-cellulose dispersion liquid into the polymer solution, uniformly mixing, adding a sizing agent and a sizing promoter in the continuous stirring process, and uniformly mixing to obtain mixed slurry;

(2) And (2) pouring the mixed slurry obtained in the step (1) into a casting machine to cast a membrane, and drying to obtain the nano cellulose membrane.

The third aspect of the present invention provides the method for preparing the nanocellulose film described in the first aspect, wherein the method for preparing the nanocellulose film is a surface hydrophobization method, and comprises the following steps:

(1) adding the nano-cellulose dispersion liquid into the polymer solution, and uniformly mixing to obtain mixed slurry;

(2) Pouring the mixed slurry obtained in the step (1) into a casting machine to carry out casting film making to obtain a nano cellulose/polymer composite film;

(3) And (3) coating a sizing agent and a sizing accelerator on the surface of the nano-cellulose/polymer composite film obtained in the step (2), and performing secondary drying to obtain the nano-cellulose film.

The production method according to the second or third aspect of the invention, wherein the ratio of the nanocellulose: polymer (b): sizing agent: the mass ratio of the sizing accelerator is 100-500: 24-100: 0.04-0.08: 0.0001 to 0.004; the mass fraction of the nano-cellulose in the nano-cellulose dispersion liquid is 2%; the mass fraction of the polymer in the polymer solution is 2%; the nano cellulose dispersion liquid and the polymer solution are both aqueous solutions;

Preferably, the conditions for cast film formation are: the speed of the casting machine is 0.1-0.5 m/min; the temperature of the heating plate is adjusted to be 60-90 ℃, and the knife edge gap is 300-450 mu m; the drying method is infrared drying.

A fourth aspect of the invention provides the use of a nanocellulose film of the first aspect or prepared according to the method of the second or third aspect for the preparation of packaging materials, solar cell substrate materials, photovoltaic devices and/or flexible circuits.

The technical route adopted by the invention is as follows:

1. Slurry hydrophobization: adding a certain amount of nano cellulose dispersion liquid into a proper amount of polymer solution, uniformly mixing by using a homogenizer, adding different amounts of sizing agent and sizing accelerator in the continuous stirring process, and uniformly mixing to obtain mixed slurry. And pouring the mixed slurry into a casting machine to cast a film, and drying to obtain the nano cellulose film with different hydrophobicities.

2. surface hydrophobization method: adding a certain amount of nano-cellulose dispersion liquid into a proper amount of polymer solution, and uniformly mixing by using a homogenizer to obtain mixed slurry. And pouring the mixed slurry into a casting machine to carry out casting film making to obtain the nano cellulose/polymer composite film. And then coating different amounts of sizing agent and sizing accelerator on the surface of the nano-cellulose/polymer composite membrane, and performing secondary drying under an infrared lamp to obtain the nano-cellulose membrane with the hydrophobic surface.

the nano-cellulose is one or more of nano-microcrystalline cellulose, microfibrillated cellulose, nano-fibrillated cellulose and the modified products;

The modified products comprise cationization, carboxymethylation, carboxylation and hydroxypropyl methylation products of nano microcrystalline cellulose, microfibrillated cellulose and nano fibrillated cellulose;

the degree of substitution of the cationized modified product is 0.03-0.2, the degree of substitution of the carboxymethylated modified product is 0.05-0.4, and the degree of substitution of the hydroxypropyl methylated modified product is 0.05-0.6.

the polymer is one or mixture of at least two of guar gum, gelatin, carrageenan, gellan gum, locust bean gum, furcellaran, cellulose gum or soybean protein;

The sizing agent is any one of Alkenyl Succinic Anhydride (ASA) and Alkyl Ketene Dimer (AKD) or a mixture of the alkenyl succinic anhydride and the Alkyl Ketene Dimer (AKD) in any proportion;

The sizing accelerator is any one of poly (diallyl dimethyl ammonium chloride), cationic polyacrylamide, polyethyleneimine, polyvinylamine and chitosan or a mixture of the poly (diallyl dimethyl ammonium chloride), the cationic polyacrylamide, the polyethyleneimine, the polyvinylamine and the chitosan in any proportion;

Typical processes for route 1 and route 2 are as follows:

1. Mixing 100-500 parts of nano cellulose dispersion liquid and 24-100 parts of polymer solution, adding 0.04-0.08 part of sizing agent and 0.0001-0.004 part of sizing accelerator, and stirring to obtain mixed slurry; pouring the mixed slurry into a casting machine for casting film, adjusting the speed of the casting machine to 0.1-0.5 m/min, adjusting the temperature of a heating plate to 60-90 ℃, adjusting the knife edge gap to 300-450 mu m, and performing infrared drying to obtain the final product.

The adjustable hydrophilic and hydrophobic nano cellulose film prepared by the in-slurry hydrophobic method comprises the following materials in proportion:

Nano-cellulose: polymer (b): sizing agent: and (3) sizing accelerator being 100-500: 24-100: 0.04-0.08: 0.0001 to 0.004 m/m;

Polymer (b): 2% of water, and m/m;

Nano-cellulose: 2% of water, m/m.

2. Mixing 100-500 parts of nano cellulose dispersion liquid and 24-100 parts of polymer solution, and stirring to obtain mixed slurry; pouring the mixed slurry into a casting machine for casting to prepare a membrane, adjusting the speed of the casting machine to 0.1-0.5 m/min, adjusting the temperature of a heating plate to 60-90 ℃, adjusting the knife edge gap to 300-450 mu m, and drying to obtain the nano cellulose membrane without the sizing agent. And (3) coating 0.04-0.08 part of sizing agent and 0.0001-0.004 part of sizing accelerator on the surface of the dried nano cellulose film in sequence, and then carrying out infrared drying to obtain a final product.

The adjustable hydrophilic and hydrophobic nano cellulose film prepared by the surface hydrophobic method comprises the following materials in parts by weight:

nano-cellulose: polymer (b): sizing agent: and (3) sizing accelerator being 100-500: 24-100: 0.04-0.08: 0.0001 to 0.004 m/m;

Polymer (b): 2% of water, and m/m;

Nano-cellulose: 2% of water, m/m.

Compared with the prior art, the invention can promote the sizing agent to react with the cellulose hydroxyl and the polymer efficiently under the action of the sizing accelerant, introduces hydrophobic groups on the surfaces of the cellulose and the polymer through an internal sizing method and a surface sizing method, prepares the hydrophobic cellulose film through an industrially mature tape casting method, obviously improves the sizing degree of the cellulose film and shortens the preparation time.

The contact angle of the surface of the prepared film is 110.63 degrees; has good mechanical property, oxygen resistance and printability. The invention has the advantages of green, large-scale production, simple operation and the like, and the preparation method is simple and efficient and has obvious film hydrophobic effect.

The controllable hydrophilic and hydrophobic nano cellulose film provided by the invention has the following beneficial effects:

1. the nano cellulose film with adjustable hydrophilicity and hydrophobicity prepared by the invention has high hydrophobic contact angle, high water and oxygen barrier capability, good stability and good printability.

2. The invention adopts the method of infrared secondary heating and adding sizing agent, thus improving the sizing degree of the nano cellulose membrane.

3. The method for preparing the film is simple and easy to implement, convenient to operate and short in preparation period; the industrially mature tape casting method is adopted, and the nano cellulose film with adjustable and controllable hydrophilicity and hydrophobicity can be produced in a large scale.

Detailed Description

the invention is further illustrated by the following specific examples, which, however, are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

This section generally describes the materials used in the testing of the present invention, as well as the testing methods. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. It will be apparent to those skilled in the art that the materials and methods of operation used in the present invention are well within the skill of the art, provided that they are not specifically illustrated.

The reagents and instrumentation used in the following examples are as follows:

reagent:

Guar gum, purchased from north Hebei, chemical Limited;

Polydiallyldimethylammonium chloride, 2,2,6, 6-tetramethylpyridin-1-yloxy radical, available from sigma aldrich trade, ltd;

AKD, available from baioyole biotechnology limited;

Cationic polyacrylamides, available from maya reagent, inc;

Bleached kraft softwood pulp available from cral Arraco;

Bleached hardwood chemical pulp, available from Shandong Rizhang Sensen Bo pulp paper, Inc.;

Concentrated sulfuric acid, purchased from Beijing chemical plant;

NaBr, NaOH, gelatin, 2, 3-epoxypropyltrimethylammonium chloride, isopropanol, ASA, available from Allantin Biotechnology Ltd;

NaClO, available from Afahesar chemical Co., Ltd;

Propylene oxide, available from Shanghai Michelin Biotechnology, Inc.

The instrument comprises the following steps:

a casting machine was purchased from Permama plastics machines, Inc. of Dongguan, model BMSJ110X 32-2100.

High pressure homogenizer available from PhD technologies, Inc., USA, model D-3M.