阅读说明：本技术 一种新型疏水改性纳米纤维素及其制备方法和应用 (Novel hydrophobically modified nano-cellulose and preparation method and application thereof ) 是由 沙力争 马超 赵会芳 张学金 邱苏鹏 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种新型疏水改性纳米纤维素及其制备方法和应用,属于功能涂料技术领域。本发明首先用2,2,6,6-四甲基哌啶氧化物(TEMPO)氧化预处理纤维素,得到带有羧基的纤维素,然后进行高压均质得到纳米纤维素；再采用两步法疏水改性纳米纤维素,第一步用戊二酸酐、丙酸酐作为复合酸酐为酯化改性纳米纤维素的试剂；第二步用1-三癸胺和正癸胺通过静电吸附作用与酯化改性的纳米纤维素反应形成络合物,即所述的新型疏水改性纳米纤维素。将本发明制备的改性纳米纤维素涂敷在书画纸表面,可显著改善书画纸的强度性能,且由于纳米纤维素尺寸小,更容易沉积在纸张表面或者渗透孔隙,可增强纸的水蒸气阻隔性能以及疏水性,延长保存时间。(The invention discloses novel hydrophobically modified nano-cellulose and a preparation method and application thereof, belonging to the technical field of functional coatings. Firstly, oxidizing and pretreating cellulose by using 2,2,6, 6-tetramethylpiperidine oxide (TEMPO) to obtain cellulose with carboxyl, and then, carrying out high-pressure homogenization to obtain nano-cellulose; hydrophobic modification of the nano-cellulose is carried out by adopting a two-step method, and glutaric anhydride and propionic anhydride are used as composite anhydride as reagents for esterifying and modifying the nano-cellulose in the first step; and in the second step, 1-tridecylamine and n-decylamine are reacted with the esterified nano-cellulose through electrostatic adsorption to form a complex, namely the novel hydrophobic modified nano-cellulose. The modified nano-cellulose prepared by the method is coated on the surface of the writing and painting paper, so that the strength performance of the writing and painting paper can be obviously improved, and the nano-cellulose is small in size, so that the nano-cellulose is more easily deposited on the surface of the paper or permeates pores, the water vapor barrier property and the hydrophobicity of the paper can be enhanced, and the storage time can be prolonged.)

1. A preparation method of novel hydrophobic modified nano-cellulose is characterized by comprising the following steps: the method specifically comprises the following steps:

(1) crushing and uniformly stirring fiber slurry, then carrying out oxidation pretreatment on the fiber slurry by adopting a TEMPO/NaClO/NaBr system, and carrying out suction filtration and washing to obtain oxidized cellulose;

(2) preparing the oxidized cellulose obtained in the step (1) into a suspension with the concentration of 1-2%, and then carrying out high-pressure homogenization treatment to obtain a nano cellulose suspension;

(3) rotationally evaporating the nano-cellulose suspension obtained in the step (2) to obtain gel-like nano-cellulose; then adding N-N-dimethylformamide into the gel-like nano-cellulose according to the proportion, uniformly dispersing by ultrasonic, heating to 80-90 ℃, and stirring at constant temperature for 4-6 h; after stirring, continuously adding glutaric anhydride, propionic anhydride and 4-dimethylamino pyridine according to the proportion, and obtaining reaction liquid 1 after ultrasonic dispersion is uniform; heating the reaction solution 1 to 80-120 ℃ for constant-temperature reaction for 4-8h, cooling after the reaction is finished, centrifuging and washing a product to obtain esterified modified nano-cellulose;

(4) respectively adding a 1-tridecylamine solution and an n-decylamine solution into the esterified and modified nanocellulose obtained in the step (3) according to the ratio, uniformly mixing to obtain a reaction solution 2, adjusting the pH value of the reaction solution 2 to be neutral, and stirring at constant temperature of 40-80 ℃ for reaction for 2-6 hours; and after the reaction is finished, centrifuging and washing the product, and finally carrying out dialysis separation treatment to obtain the novel hydrophobic modified nano-cellulose.

2. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the fiber pulp in the step (1) is any one of wood pulp, cotton pulp, hemp pulp, bamboo pulp and reed pulp.

3. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: in the fiber slurry obtained in the step (1), the mass ratio of oven-dried fibers, 2,6, 6-tetramethylpiperidine oxide, sodium bromide and sodium hypochlorite is 1: 0.01-0.02: 0.05-0.2: 6-10.

4. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the number of times of the high-pressure homogenization treatment in the step (2) is 10-15, and the pressure adopted by the high-pressure homogenization treatment is 800-1000 bar.

5. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the dosage ratio of the oven-dried nano-cellulose to the N-N-dimethylformamide in the nano-cellulose water suspension in the step (3) is 1-2 parts by mass: 60-100 parts by volume, wherein: the mass portion and the volume portion are as follows: ml is used as a reference.

6. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the mass ratio of the oven-dried nano-cellulose to the glutaric anhydride, the propionic anhydride and the 4-dimethylamino pyridine in the nano-cellulose water suspension in the step (3) is 1: 20: 20: 0.6.

7. the method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the concentration of the 1-tridecylamine solution and the concentration of the n-decylamine solution in the step (4) are both 3-6%.

8. The method for preparing the novel hydrophobically modified nanocellulose according to claim 1, characterized in that: the mass ratio of the esterified and modified nano-cellulose to the 1-tridecylamine in the 1-tridecylamine solution to the n-decylamine in the n-decylamine solution is 1: 0.1-0.45: 0.1-0.45.

9. The novel hydrophobically modified nanocellulose prepared by the method of preparing the novel hydrophobically modified nanocellulose as claimed in any one of claims 1 to 8.

10. Use of the novel hydrophobically modified nanocellulose prepared by the process of any of claims 1 to 8, wherein: can be used for preparing writing and painting paper.

Technical Field

The invention belongs to the technical field of functional coatings, and particularly relates to novel hydrophobically modified nano-cellulose and a preparation method and application thereof.

Background

As is well known, in domestic artistic creation, particularly in painting and calligraphy artistic creation, artists or artistic enthusiasts pursue expressive force in individuality and microcosmic aspects, so that the water absorption and color ink reducibility of domestic artistic paper are different, and the difference requirement of products is very large. Therefore, the differential water absorbability and the ink absorbability of the painting and calligraphy paper become one of the key links of the production of the artistic paper. The painting and calligraphy paper has low strength, is easy to damage, has large moisture absorption and is easy to mildew, and the painting and calligraphy paper also has special attention in production.

Disclosure of Invention

In view of the problems or defects of the prior art, the present invention aims to provide a novel hydrophobically modified nanocellulose, and a preparation method and applications thereof. The invention mainly utilizes the combination of esterification modification and amide reaction to carry out hydrophobic modification on the nano-cellulose and carry out surface sizing on the writing and painting paper, thereby solving the technical problems of the prior writing and painting paper.

In order to achieve the above objects of the present invention, the present invention designs a novel method for preparing hydrophobically modified nanocellulose: firstly, oxidizing and pretreating cellulose by using 2,2,6, 6-tetramethylpiperidine oxide (TEMPO) to obtain cellulose with carboxyl, and then carrying out high-pressure homogenization to obtain nano-cellulose; hydrophobic modification of the nano-cellulose is carried out by adopting a two-step method, and glutaric anhydride and propionic anhydride are used as composite anhydride as reagents for esterifying and modifying the nano-cellulose in the first step; and in the second step, 1-tridecylamine and n-decylamine are reacted with the esterified nano-cellulose through electrostatic adsorption to form a complex, namely the novel hydrophobic modified nano-cellulose.

The technical scheme adopted by the invention is as follows:

a preparation method of novel hydrophobically modified nanocellulose specifically comprises the following steps:

(1) crushing and uniformly stirring fiber slurry, then carrying out oxidation pretreatment on the fiber slurry by adopting a TEMPO (2,2,6, 6-tetramethylpiperidine oxide)/NaClO/NaBr system, and carrying out suction filtration and washing to obtain oxidized cellulose;

(2) preparing the oxidized cellulose obtained in the step (1) into a suspension with the concentration of 1-2%, and then carrying out high-pressure homogenization treatment to obtain a nano cellulose suspension;

(3) rotationally evaporating the nano-cellulose suspension obtained in the step (2) to obtain gel-like nano-cellulose; then adding N-N-dimethylformamide into the gel-like nano-cellulose according to the proportion, uniformly dispersing by ultrasonic, heating to 80-90 ℃, and stirring at constant temperature for 4-6 h; after stirring, continuously adding glutaric anhydride, propionic anhydride and 4-dimethylamino pyridine according to the proportion, and obtaining reaction liquid 1 after ultrasonic dispersion is uniform; heating the reaction solution 1 to 80-120 ℃ for constant-temperature reaction for 4-8h, cooling after the reaction is finished, centrifuging and washing a product to obtain esterified modified nano-cellulose;

(4) respectively adding a 1-tridecylamine solution and an n-decylamine solution into the esterified and modified nanocellulose obtained in the step (3) according to the ratio, uniformly mixing to obtain a reaction solution 2, adjusting the pH value of the reaction solution 2 to be neutral, and stirring at constant temperature of 40-80 ℃ for reaction for 2-6 hours; after the reaction is finished, centrifuging and washing the product, and finally carrying out dialysis separation treatment to obtain the novel hydrophobic modified nano-cellulose.

Further, according to the above technical scheme, the fiber pulp in the step (1) may be any one of wood pulp, cotton pulp, hemp pulp, bamboo pulp, reed pulp, and the like.

Preferably, in the above technical solution, the wood pulp is any one of hardwood pulp or softwood pulp.

Further, according to the technical scheme, in the fiber slurry obtained in the step (1), the mass ratio of the oven-dried fiber to the 2,2,6, 6-tetramethylpiperidine oxide to the sodium bromide to the sodium hypochlorite is 1: 0.01-0.02: 0.05-0.2: 6-10.

Further, in the above technical solution, the pressure adopted in the high-pressure homogenization treatment in the step (2) is 800-1000 bar.

Further, in the technical scheme, the high-pressure homogenization treatment in the step (2) is performed for 10-15 times, and the time for each treatment is 30-60 s.

Further, in the above technical solution, the stirring speed in step (3) is 400-800rpm, more preferably 500-600 rpm.

Further, according to the technical scheme, the use amount ratio of the oven-dried nano-cellulose to the N-N-dimethylformamide in the nano-cellulose water suspension in the step (3) is 1-2 parts by mass: 60-100 parts by volume, wherein: the mass portion and the volume portion are as follows: ml is used as a reference.

Further, according to the technical scheme, the mass ratio of the oven-dried nano-cellulose to the glutaric anhydride, the propionic anhydride and the 4-dimethylaminopyridine in the nano-cellulose water suspension in the step (3) is 1: 20: 20: 0.6.

further, in the above technical scheme, the concentration of the 1-tridecylamine solution in the step (4) is 3-6%, and the specific preparation method of the 1-tridecylamine solution is as follows: adding 3-6g of 1-tridecylamine into 100mL of N-N Dimethylformamide (DMF), and uniformly stirring.

Further, in the above technical scheme, the concentration of the n-decylamine solution in the step (4) is 3-6%, and the specific preparation method of the n-decylamine solution is as follows: adding 3-6g of N-decylamine into 100mL of N-N Dimethylformamide (DMF), and uniformly stirring.

Further, in the above technical scheme, the mass ratio of the esterified and modified nanocellulose in the step (4), 1-tridecylamine in the 1-tridecylamine solution, and n-decylamine in the n-decylamine solution is 1: 0.1-0.45: 0.1-0.45.

Further, in the above technical solution, the stirring speed in step (4) is 400-800rpm, and more preferably 600 rpm.

The second purpose of the invention is to provide the novel hydrophobic modified nano-cellulose prepared by the method.

The third purpose of the invention is to provide the application of the novel hydrophobic modified nano-cellulose prepared by the method, which can be used for preparing writing and painting paper.

Compared with the prior art, the novel hydrophobically modified nano-cellulose and the preparation method and the application thereof have the following beneficial effects:

(1) the invention controls the surface sizing of the writing and painting paper by controlling the process formula of the modified nano-cellulose, such as concentration, dosage, surface sizing speed and the like, thereby controlling different water absorbability and ink absorbability and further realizing differential adjustment.

(2) The nanocellulose modified by the two-step method is coated on the writing and painting paper in a surface sizing mode, and the nanocellulose is small in size, so that the nanocellulose is more easily deposited on the surface of the paper or permeates pores, the water vapor barrier property and the hydrophobicity of the paper can be enhanced, and therefore the nanocellulose is less prone to absorb moisture and mildew when the environmental humidity is high, and the storage time of the nanocellulose is prolonged.

(3) The modified nano-cellulose prepared by the method is coated on the surface of the writing and painting paper, so that the strength performance of the writing and painting paper can be obviously improved, and meanwhile, the chemical components of the adopted modified nano-cellulose are the same as those of the plant fibers of the writing and painting paper, so that the writing of the writing and painting paper is not adversely affected.

(4) The nano-cellulose adopted in the invention is derived from plant fiber raw materials, and has the advantages of environmental protection, degradability and the like.

Drawings

Fig. 1 is a flow chart of a preparation process of the novel hydrophobically modified nanocellulose of the present invention.

FIG. 2 is a process flow diagram for preparing writing and painting paper by using the novel hydrophobically modified nanocellulose.

Detailed Description

The present invention will be described in further detail below with reference to examples. The present invention is implemented on the premise of the technology of the present invention, and the detailed embodiments and specific procedures are given to illustrate the inventive aspects of the present invention, but the scope of the present invention is not limited to the following embodiments.

Various modifications to the precise description of the invention will be readily apparent to those skilled in the art from the information contained herein without departing from the spirit and scope of the appended claims. It is to be understood that the scope of the invention is not limited to the procedures, properties, or components defined, as these embodiments, as well as others described, are intended to be merely illustrative of particular aspects of the invention. Indeed, various modifications of the embodiments of the invention which are obvious to those skilled in the art or related fields are intended to be covered by the scope of the appended claims.

For a better understanding of the invention, and not as a limitation on the scope thereof, all numbers expressing quantities, percentages, and other numerical values used in this application are to be understood as being modified in all instances by the term "about". Accordingly, unless expressly indicated otherwise, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Two key properties of the writing and drawing papers developed in this invention are water resistance and physical strength properties (tear index, length at break, etc.). The higher the concentration of the modified nanocellulose is, the better the hydrophobicity of the paper is, the water absorption is deteriorated, while the addition of the modified nanocellulose slightly improves the physical strength property, but also needs to consider the influence of the cost and the physical strength of the paper, so that it is necessary to select an appropriate concentration for surface sizing. The method firstly uses 2,2,6, 6-tetramethyl piperidine oxide (TEMPO) to oxidize and pretreat the cellulose, and then carries out high-pressure homogenization, the dispersion performance of the prepared nano cellulose in water is greatly improved, and the generated carboxyl has negative charges and has charge repulsion, thereby improving the dispersion performance.

According to the invention, glutaric anhydride and propionic anhydride are used as the composite anhydride as the reagent of the esterification modified nano-cellulose to carry out esterification reaction with the prepared nano-cellulose, so that the hydrophobicity is obviously improved.

The 1-tridecylamine and the n-decylamine of the invention react with the esterified nano-cellulose through electrostatic adsorption to form a complex, so that the hydrophobicity is further improved.

The concentration of each reagent of the present invention refers to the mass/volume percent concentration of the dispersoid and the dispersion medium in g/mL.