阅读说明：本技术 微胶囊纸的制备方法 (Preparation method of microcapsule paper ) 是由 宋特 吴晓彪 隋涛 王伟 余春柳 于 2020-12-29 设计创作，主要内容包括：本发明公开一种微胶囊纸的制备方法。包括以下步骤：1)用纸页成型器抄造定量为15-20g/m2的薄型湿纸幅；2)通过层间加填工艺将微胶囊包络体系加入到两张湿纸张之间,3)利用压榨和干燥工艺制备出高包络微胶囊纸；其中,所述的微胶囊包络体系的制备方法为：21)将纳米原纤化纤维素与β-环状糊精为主体的微胶囊混合搅拌；形成CNF/微胶囊分散体系；22)常温下,在CNF/微胶囊分散体系中加入1-3％丙烯酸锂溶液进行预处理5-15min；23)将预处理后的CNF/微胶囊分散体系进行离心洗涤至中性；24)将洗涤后的CNF/微胶囊分散体系中再包络10％-15％固含量的微胶囊,同时辅以超声波和搅拌协同分散作用。本发明逐级包络微胶囊预包络体系可以使得微胶囊的加填量远远高于普通纸浆和微胶囊混合抄造纸张中微胶囊含量。(The invention discloses a preparation method of microcapsule paper. The method comprises the following steps: 1) making thin wet paper web with weight of 15-20g/m2 with paper sheet former; 2) adding the microcapsule enveloping system between two pieces of wet paper by an interlayer filling process, and 3) preparing the high enveloping microcapsule paper by utilizing a squeezing and drying process; the preparation method of the microcapsule enveloping system comprises the following steps: 21) mixing and stirring the nanofibrillated cellulose and the microcapsule taking the beta-cyclodextrin as the main body; forming a CNF/microcapsule dispersion; 22) at normal temperature, adding 1-3% lithium acrylate solution into the CNF/microcapsule dispersion system for pretreatment for 5-15 min; 23) centrifugally washing the pretreated CNF/microcapsule disperse system to be neutral; 24) and enveloping the microcapsules with solid content of 10-15% in the washed CNF/microcapsule disperse system, and simultaneously assisting ultrasonic waves and stirring for synergistic dispersion. The gradual enveloping microcapsule pre-enveloping system can ensure that the filling amount of the microcapsules is far higher than the microcapsule content in the common paper pulp and microcapsule mixed papermaking paper.)

1. The preparation method of the microcapsule paper is characterized by comprising the following steps of:

1) making thin wet paper web with weight of 15-20g/m2 with paper sheet former;

2) the microcapsule enveloping system is added between two pieces of wet paper by an interlayer filling process,

3) preparing high-envelope microcapsule paper by using a squeezing and drying process;

the preparation method of the microcapsule enveloping system comprises the following steps:

21) mixing and stirring the nanofibrillated cellulose and the microcapsule taking the beta-cyclodextrin as the main body; forming a CNF/microcapsule dispersion;

22) at normal temperature, adding 1-3% lithium acrylate solution into the CNF/microcapsule dispersion system for pretreatment for 5-15 min;

23) centrifugally washing the pretreated CNF/microcapsule disperse system to be neutral;

24) and enveloping the microcapsules with solid content of 10-15% in the washed CNF/microcapsule disperse system, and simultaneously assisting ultrasonic waves and stirring for synergistic dispersion.

2. The method for preparing the micro-encapsulated paper as set forth in claim 1, further comprising:

25) adding cationic starch in the process of stirring and ultrasonic cavitation synergistic treatment.

3. The method for preparing the micro-encapsulated paper according to claim 1, wherein the method comprises the following steps:

31) adding 30-40% w/w of microcapsule taking beta-cyclodextrin as main body into nanofibrillated cellulose with solid content of 1-3%, mixing and stirring at the stirring speed of 1500-2000rpm for 20-30 min; simultaneously, uniformly dispersing the mixture by ultrasonic wave synergistic treatment to form a CNF/microcapsule dispersion system;

32) at normal temperature, adding 1-3% lithium acrylate solution into the CNF/microcapsule dispersion system for pretreatment for 5-15 min;

33) centrifugally washing the CNF/microcapsule dispersion system for 4-6 times until the system is washed to be neutral;

34) enveloping the microcapsules with solid content of 10-15% in the washed CNF/microcapsule disperse system, and simultaneously assisting ultrasonic and stirring for synergistic dispersion;

35) stirring the CNF/microcapsule under the condition of keeping the content of the CNF/microcapsule at 3-5% of solid content; the stirring speed is 1500-; carrying out ultrasonic cavitation cooperative treatment; in the process, 0.01-0.03% of cationic starch is added.

Technical Field

The invention relates to a preparation method of microcapsule paper.

Background

The addition of microcapsules to paper can impart new functionality to the paper. For example, the addition of the fragrant microcapsules in the paper can ensure that the fragrance of the paper has a long-term retention effect; the microcapsule with porous property can be highly filled by the coating effect of the nano-cellulose, the adsorption performance of paper is enhanced, and the microcapsule has important application in green packaging or home decoration.

The conventional microcapsule is mixed with paper, the filling amount of the microcapsule is low, a large amount of microcapsules can be lost in the papermaking process, and the mixed papermaking effect is not obvious.

Disclosure of Invention

In order to overcome the defects, the invention provides a preparation method of microcapsule paper, which adopts CNF as a pre-enveloping body structure and can greatly increase the content of microcapsules in paper.

In order to achieve the purpose, the preparation method of the microcapsule paper comprises the following steps:

1) making thin wet paper web with weight of 15-20g/m2 with paper sheet former;

2) the microcapsule enveloping system is added between two pieces of wet paper by an interlayer filling process,

3) preparing high-envelope microcapsule paper by using a squeezing and drying process;

the preparation method of the microcapsule enveloping system comprises the following steps:

21) mixing and stirring the nanofibrillated cellulose and the microcapsule taking the beta-cyclodextrin as the main body; forming a CNF/microcapsule dispersion;

22) at normal temperature, adding 1-3% lithium acrylate solution into the CNF/microcapsule dispersion system for pretreatment for 5-15 min;

23) centrifugally washing the pretreated CNF/microcapsule disperse system to be neutral;

24) enveloping the microcapsules with solid content of 10-15% in the washed CNF/microcapsule disperse system, and simultaneously assisting ultrasonic wave and stirring for synergistic dispersion;

further, the method also comprises the following steps:

25) adding cationic starch in the process of stirring and ultrasonic cavitation synergistic treatment.

Further, the method specifically comprises the following steps:

31) adding 30-40% w/w of microcapsule taking beta-cyclodextrin as main body into nanofibrillated cellulose with solid content of 1-3%, mixing and stirring at the stirring speed of 1500-2000rpm for 20-30 min; simultaneously, uniformly dispersing the mixture by ultrasonic wave synergistic treatment to form a CNF/microcapsule dispersion system;

32) at normal temperature, adding 1-3% lithium acrylate solution into the CNF/microcapsule dispersion system for pretreatment for 5-15 min;

33) centrifugally washing the CNF/microcapsule dispersion system for 4-6 times until the system is washed to be neutral;

34) enveloping the microcapsules with solid content of 10-15% in the washed CNF/microcapsule disperse system, and simultaneously assisting ultrasonic and stirring for synergistic dispersion;

35) stirring the CNF/microcapsule under the condition of keeping the content of the CNF/microcapsule at 3-5% of solid content; the stirring speed is 1500-; carrying out ultrasonic cavitation cooperative treatment; in the process, 0.01-0.03% of cationic starch is added.

The invention adopts the nanocellulose fiber to gradually envelop the microcapsule pre-enveloping system, so that the filling amount of the microcapsules is far higher than the content of the microcapsules in the common paper pulp and microcapsule mixed papermaking paper, and the microcapsules can be fixed in a rich nanocellulose network structure and can be uniformly dispersed among layers. In addition, in the laminating process, due to the abundant net-shaped cross-linking structure of the nano-cellulose and the existence of a large amount of hydroxyl on the surface, a large amount of hydrogen bonds are generated between the upper layer and the lower layer in the laminating process, and the interlayer bonding strength between the two layers is increased.

Detailed Description

Examples

Chemical pulp board of softwood and hardwood with beating degree of 40-50 DEG SR; the mass fraction (retention aid) of the cationic polyacrylamide is 0.03-0.05%;

a paper sheet former is adopted to manufacture thin paper with the fixed quantity of 15-20g/m2, a CNF/microcapsule enveloping system is added between two wet paper webs through an interlayer filling process to be pressed and dried, and a great amount of hydroxyl on the surfaces of nanocellulose and microcapsules are utilized to form hydrogen bond connection with upper and lower paper webs, so that the connection between the upper and lower layers is tighter, the microcapsules can be completely filled into the paper, a great amount of loss of the microcapsules cannot be caused, and the full filling effect is achieved.

The preparation process of the CNF/microcapsule envelope system is as follows:

(1) mixing and stirring the nanofibrillated cellulose with the solid content of 1-3% and the microcapsule (the adding amount is 30-40% w/w) taking the beta-cyclodextrin as the main body; the stirring speed is 1500-; meanwhile, uniformly dispersing the mixture with ultrasonic wave (fixed frequency and same time) to form a CNF/microcapsule dispersion system.

(2) At normal temperature, 1-3% lithium acrylate solution is added into a CNF/microcapsule dispersion system for pretreatment for 5-15min, so that the amorphous region structure on the surface of cellulose is looser and more free hydroxyl groups are exposed, and a richer hydroxyl network structure is formed.

(3) And (4) centrifugally washing the system for 4-6 times until the system is washed to be neutral.

(4) Then the microcapsule with solid content of 10-15% is enveloped, and simultaneously ultrasonic wave and stirring are assisted to realize synergistic dispersion, so that the characteristic of the microcapsule adding process in the system is achieved to the maximum extent.

(5) Stirring (stirring speed 1500-. A novel nano-fibrillating cellulose/cationic starch/microcapsule enveloping body with the maximum enveloping microcapsule effect of nano-cellulose is formed.

In the process, the nano-cellulose has high fibrillation degree, large specific surface area and abundant free hydroxyl groups, so that abundant net structures can be formed in the matrix material. The nano-cellulose has special properties which are not possessed by conventional fibers, such as high water retention value, good cohesive force, thickening property, suspension property, stability, dispersibility and the like, and the microcapsule is a micron-level granular substance taking beta-cyclic dextrin as a main body. Because the surfaces of the microcapsule and the nano-cellulose have a large amount of free hydroxyl groups and the surfaces of the microcapsule and the nano-cellulose have electronegativity, the cationic starch is added to change the potential on the surface of the envelope system, so that the system is more stable.

The gradual enveloping process of the nano fibrillated cellulose/microcapsule enveloping system is compared with the process of one-time enveloping microcapsules:

(1) the construction of the disposable microcapsule/nanofibrillated cellulose can not reach the ideal addition amount of the microcapsule, the addition amount can reach the amount of 30-40% w/w, if the microcapsule is added, the system is sticky, and is difficult to be uniformly dispersed through ultrasonic waves and stirring action, so that the enveloping system is not uniformly dispersed, and the microcapsule can not reach the ideal effect in the paper sheet after the subsequent paper forming.

(2) The nanocellulose gradually envelops the microcapsules, so that the addition amount of the microcapsules is higher than that of the microcapsules added at one time. The addition amount can reach 40-55%. The microcapsule/nano-cellulose system added for one time is pretreated and swollen by the lithium acrylate solution, so that the molecular cohesion of an amorphous area is reduced, the nano-fibrillated cellulose is further softened, more free hydroxyl groups and a space net structure are exposed, and the system can further contain the microcapsule by the way. The content of the additive can be further increased by 10-15% on the basis of one-time addition. The microcapsule filling amount of the system is maximized.

The microcapsules reach the maximum enveloping structure in a nanocellulose enveloping system through a step-by-step enveloping process, the microcapsules are tightly enveloped in the nanocellulose through the unique network structure of the nanocellulose, and the filling amount of the microcapsules is increased as much as possible by adopting a mode of filling the microcapsules between layers.

Compared with the prior art, the method has the advantages that

	Amount of filling	Loss of paper-forming microcapsules
			Interlayer filling of progressive envelope system in the embodiment	40-55％	Close to 0%
Disposable envelope system interlayer filling	30-40％	Close to 0%
			Common microcapsule pulp mixing	10-20％	20-30％

The microcapsule pre-enveloping system is enveloped by the nano cellulose fiber step by step, so that the filling amount of the microcapsule is far higher than the content of the microcapsule in the paper made by mixing common paper pulp and the microcapsule, and the microcapsule can be fixed in a rich nano cellulose network structure and can be uniformly dispersed among layers. In addition, in the laminating process, due to the abundant net-shaped cross-linking structure of the nano-cellulose and the existence of a large amount of hydroxyl on the surface, a large amount of hydrogen bonds are generated between the upper layer and the lower layer in the laminating process, and the interlayer bonding strength between the two layers is increased.

	Internal bond strength
		This patent is packed between envelope system layer step by step	198-215J/m2
Disposable envelope system interlayer filling	205-218J/m2
		Common double layer composite	155-175J/m2

In the process of enveloping the microcapsules again by the nano-cellulose, through swelling treatment by a lithium acrylate solution, the reduction of the molecular cohesion of the amorphous region of the nano-cellulose in the system is ensured, the system is softened, and more microcapsules can be loaded in the system. The amount of lithium acrylate added and the pretreatment time are very important to control.

Swelling treatment of lithium acrylate at normal temperature, concentration: 1%, 2%, 3%; the treatment time is 5min, 10min and 15 min.

Experiments show that the concentration is 2%, the time is 10min, the secondary enveloping microcapsules obtained by enveloping can achieve the best process effect, and the secondary enveloping microcapsules can achieve about 15%.