CN110241649B

CN110241649B - Paper deacidification agent based on sodium phytate modified magnesium hydroxide and preparation method thereof

Info

Publication number: CN110241649B
Application number: CN201910518387.2A
Authority: CN
Inventors: 张涛
Original assignee: Hubei Taide Anxin Information Technology Co ltd
Current assignee: Hubei Taide Anxin Information Technology Co ltd
Priority date: 2019-06-15
Filing date: 2019-06-15
Publication date: 2021-08-03
Anticipated expiration: 2039-06-15
Also published as: CN110241649A

Abstract

The invention relates to a paper deacidification agent based on sodium phytate modified magnesium hydroxide and a preparation method thereof. Firstly, respectively dispersing magnesium hydroxide and sodium phytate in deionized water and an alcohol solution, then mixing the two dispersions according to a proportion for modification, and then dispersing the modified magnesium hydroxide in a mixed solvent of perfluoroheptane and petroleum ether to obtain the target deacidification agent. The deacidification agent has the advantages of easily obtained raw materials, mild reaction conditions, simple and convenient preparation and use methods, small dosage, high efficiency, good deacidification effect and uniformity.

Description

Paper deacidification agent based on sodium phytate modified magnesium hydroxide and preparation method thereof

Technical Field

The invention relates to the technical field of book and file treatment and chemical compositions, in particular to a paper deacidification agent based on sodium phytate modified magnesium hydroxide and a preparation method thereof.

Background

At present, in various libraries, museums and file organizations in China, tens of thousands of precious books, calligraphy and painting, newspapers, files and other cultural heritages which are left over all the time are kept, wherein most of the cultural heritages are written and printed by handmade paper or mechanical paper. With the passing of time, the phenomena of yellowing, mildewing, pulverization, fragmentation and the like of paper documents gradually occur, mainly caused by paper acidification. The deterioration of the paper material is macroscopically manifested as discoloration and microscopically is the structural damage (reduction in mechanical strength).

Cellulose is a main component of paper, which is quite stable under neutral and weakly alkaline conditions, not only being difficult to hydrolyze and oxidize, but also having a hydrolysis rate that increases proportionally with increasing hydrogen ion concentration, i.e., the lower the pH (the stronger the acidity) the faster the hydrolysis rate of cellulose. The degree of polymerization decreases after hydrolysis of the cellulose, which leads to a consequent decrease in the strength of the paper material, with the consequent deterioration and embrittlement of the paper as a result.

The acid in paper is from many sources, including sulfite, alum and other substances added in the paper making process, acid gas increased gradually due to industrial development, and acid substances brought by external microorganisms, mold and the like. These different routes of acidic substances are important causes of acid deterioration of paper documents.

The deacidification technology of the paper literature widely applied at present mainly comprises the following steps: the method comprises a solution method and a gas phase method, wherein the gas phase method has the defects of relatively complex process, vacuum matching, long treatment period, relatively expensive equipment and the like; the solution method is divided into a water system and an organic system, and the deacidification agent used in the water system solution method can cause paper wrinkles, adhesion, fading and the like. The use of organic solutions is therefore more advantageous in deacidification of paper. The deacidification agent used in the process typically comprises a metal oxide or hydroxide (e.g., magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, etc.) and an organic solvent (fluoroalkane). However, since the polarity of the fluoroalkane is very small, the dispersibility of the magnesium hydroxide, magnesium oxide and the like in the fluoroalkane is very poor, so that the improvement of the dispersibility of the deacidification substance in the organic solvent is a key factor for improving the efficiency of the deacidification agent.

Disclosure of Invention

The invention aims to overcome the various problems of the existing paper deacidification agent and provides the deacidification agent with simple preparation process, convenient use and good effect, and the preparation method comprises the following steps:

preparing a dispersion liquid A by using magnesium hydroxide and water, and preparing a dispersion liquid B by using sodium phytate and an alcohol solvent; mixing the dispersion liquid A and the dispersion liquid B according to a certain proportion, and then heating for reaction to obtain modified magnesium hydroxide; dispersing the modified magnesium hydroxide in a mixed solvent consisting of perfluoroheptane and petroleum ether.

Further, the concentration of the dispersion A is 1 to 10g/L, and the concentration of the dispersion B is 0.1 to 5 g/L.

Further, slowly dripping the dispersion liquid B at the normal temperature into the dispersion liquid A at the temperature of 60-75 ℃ during mixing, keeping the temperature at 60-75 ℃ after finishing dripping, reacting for 1-3h, filtering while hot, washing and drying to obtain the modified magnesium hydroxide.

Further, washing by using an alcohol solvent with the temperature of 60-75 ℃, wherein the drying temperature is 30-45 ℃, and the drying time is 18-36 h.

Further, the alcohol solvent is specifically absolute ethyl alcohol.

Furthermore, the mass ratio of the magnesium hydroxide to the sodium phytate needs to be controlled within the range of 0.5-5:0.05-2.5 when the dispersion liquid A and the dispersion liquid B are mixed.

Further, the mass ratio of the perfluoroheptane to the petroleum ether in the mixed solvent is 1530-1615: 32-66.

Furthermore, the mass ratio of the modified magnesium hydroxide to the mixed solvent is 0.01-0.5: 100.

Further, the modified magnesium hydroxide is uniformly dispersed in the mixed solvent through homogenization and ultrasonic treatment.

Another object of the present invention is to provide a deacidification agent prepared by the above method.

The modification of magnesium hydroxide by sodium phytate can also reduce the surface activation energy of magnesium hydroxide, contribute to enhancing the compatibility of magnesium hydroxide and organic solvent and improve the dispersion of magnesium hydroxide in perfluoroheptane. Sodium phytate is an important pure natural green additive, and the most remarkable characteristics of the sodium phytate are strong oxidation resistance and color protection, and residual sodium phytate has no adverse effect on paper. When the magnesium hydroxide is dispersed, the magnesium hydroxide and the modifier are prepared into dispersion liquid and then titrated, so that the magnesium hydroxide can be more fully contacted with the modifier, and the modification rate and the modification degree of the magnesium hydroxide are improved. The polarity of the perfluoroheptane is very low, and petroleum ether which is mutually soluble and has similar polarity is used as a solubilizer, so that the dispersibility of the modified magnesium hydroxide in the perfluoroheptane can be further improved.

Compared with the prior art, the invention has the following beneficial effects: the raw materials are easy to obtain, the reaction condition is mild, the preparation and use methods are simple and convenient, the adoption of complex and expensive vacuum equipment is avoided, and the cost is reduced; the composite organic solvent system is adopted, so that the adverse effect of the deacidification process on the paper is reduced; the deacidification agent has the advantages of less dosage, high efficiency, good deacidification effect and uniformity.

Drawings

FIG. 1 is a transmission electron micrograph of magnesium hydroxide before and after treatment with the modification method of example 1 of the present invention.

FIG. 2 is an electron micrograph of a paper document before and after deacidification treatment with the deacidification agent prepared in example 1 of the present invention.

Detailed Description

In order to make those skilled in the art fully understand the technical solutions and advantages of the present invention, the following embodiments are further described.

Example 1

2g of magnesium hydroxide powder is dispersed in 398g of deionized water at 70 ℃, and the mixture is uniformly stirred to obtain a dispersion A with the concentration of 5 g/L. 0.2g of sodium phytate is added into 399.8g of absolute ethyl alcohol, and the mixture is stirred uniformly to obtain a dispersion liquid B with the concentration of 0.5 g/L. The dispersion B was slowly added dropwise to the dispersion A, and the temperature of the mixed solution was maintained at 70 ℃ for 2 hours. And after the reaction is finished, carrying out suction filtration while the reaction is hot, repeatedly washing the reaction product for 3 times by using deionized water at 70 ℃, and then placing a filter cake in an environment at 35 ℃ for vacuum drying for 24 hours to obtain the modified magnesium hydroxide.

1600g of perfluoroheptane and 32g of petroleum ether are mixed and stirred uniformly to obtain a mixed solvent. Adding 2g of dried modified magnesium hydroxide into the mixed solvent, transferring the obtained mixture into a homogenizer for homogenizing for 8min under the condition of 8000r/min, and then carrying out ultrasonic treatment for 30min to obtain the deacidification agent.

Example 2

1.7g of magnesium hydroxide powder was dispersed in 198.3g of deionized water at 70 ℃ and stirred uniformly to obtain dispersion A having a concentration of 8.5 g/L. 0.2g of sodium phytate is added into 199.8g of absolute ethyl alcohol, and the mixture is stirred uniformly to obtain 1g/L dispersion liquid B. The dispersion B was slowly added dropwise to the dispersion A, and the temperature of the mixed solution was maintained at 70 ℃ for 2 hours. And after the reaction is finished, carrying out suction filtration while the reaction is hot, repeatedly washing the reaction product for 3 times by using deionized water at 70 ℃, and then placing a filter cake in an environment at 35 ℃ for vacuum drying for 24 hours to obtain the modified magnesium hydroxide.

1615g of perfluoroheptane and 35g of petroleum ether are mixed and stirred uniformly to obtain a mixed solvent. Adding 1.5g of dried modified magnesium hydroxide into the mixed solvent, transferring the obtained mixture into a homogenizer for homogenizing for 8min under the condition of 8000r/min, and then carrying out ultrasonic treatment for 30min to obtain the deacidification agent.

Comparative example 1

Putting the magnesium hydroxide powder in an environment with the temperature of 35 ℃ for vacuum drying for 24h, then directly mixing the magnesium hydroxide powder and perfluoroheptane according to the proportion of 1:800, transferring the obtained mixture into a homogenizer for homogenizing for 8min under the condition of 8000r/min, and then carrying out ultrasonic treatment for 30min to obtain the deacidification agent.

Comparative example 2

Comparative example 2 is substantially the same as comparative example 1 except that: the magnesium hydroxide, the perfluoroheptane and the petroleum ether are directly mixed according to the proportion of 1:800: 40.

Comparative example 3

Comparative example 3 is substantially the same as comparative example 1 except that: the magnesium hydroxide, the perfluoroheptane and the sodium phytate are directly mixed according to the proportion of 1:800: 0.2.

The paper documents were subjected to a soaking deacidification treatment (soaking time 3min) at room temperature using the deacidification agents prepared in examples 1 and 2 and comparative examples 1 to 3, and then taken out to air-dry. The deacidification agent and the treated paper were tested for properties as shown in table 1 below.

TABLE 1 Deacidification Effect of different deacidification agents

The transmission electron microscope analysis of magnesium hydroxide before and after modification in example 1 showed the results shown in FIG. 1 (left before modification and right after modification). As can be seen from FIG. 1, the surface of the modified magnesium hydroxide is changed from smooth to uneven and has a layer of coating, which shows that the surface energy of the magnesium hydroxide can be effectively reduced by modification, and meanwhile, the modifying agent is coated on the surface of the magnesium hydroxide in the form of a coating layer, which is beneficial to the dispersion of the magnesium hydroxide in the perfluoroheptane.

The paper document was subjected to a soaking deacidification treatment at room temperature using the deacidification agent prepared in example 1 (soaking time 3min), then taken out and air-dried, and the microstructure changes before and after deacidification treatment of the paper document were analyzed by a scanning electron microscope, and the results are shown in fig. 2 (left before deacidification and right after deacidification). As can be seen from fig. 2, a large number of solid particles are attached to the surface of the paper fiber after the deacidification treatment, and the structure of the solid particles is substantially consistent with that of the nano-magnesium hydroxide, which indicates that the magnesium hydroxide particles are attached to the surface of the paper fiber to achieve the deacidification effect.

The influence of the soaking time on the deacidification effect was examined by using the deacidification agent obtained in example 1 in the same manner, and the results are shown in table 2.

TABLE 2 influence of soaking time on deacidification Effect

The above experimental results show that: the soaking time is too short (below 1 min), the adhesion amount of the deacidification agent on the surface of the paper is less, and the paper acidity treatment is not obvious; the soaking time is too long (more than 5 min), the pH value is not obviously increased, and the appearance of obvious white accumulation on the surface of the paper can be observed macroscopically, which can influence the basic physical properties of the paper. The moderate soaking time can ensure the deacidification effect of the paper to be obvious and the physical performance of the paper to be basically unchanged, the micro deacidification agent has enough adhesion on the paper and the macro paper has no obvious white accumulation on the surface, so the soaking time is preferably controlled to be 1-5 min. The experiment also shows that the short-time soaking treatment of the perfluoroheptane-petroleum ether composite solvent system has little influence on the basic performances of paper, such as brittleness and the like.

Similar effects were obtained by conducting the above experiment using the deacidification agent obtained in example 2.

Claims

1. The preparation method of the paper deacidification agent based on the sodium phytate modified magnesium hydroxide is characterized by comprising the following steps: preparing a dispersion liquid A by using magnesium hydroxide and water, and preparing a dispersion liquid B by using sodium phytate and an alcohol solvent; mixing the dispersion liquid A and the dispersion liquid B according to a certain proportion, and then heating for reaction to obtain modified magnesium hydroxide; dispersing modified magnesium hydroxide in a mixed solvent consisting of perfluoroheptane and petroleum ether, wherein the mass ratio of the perfluoroheptane to the petroleum ether is 1530-1615:32-66, and the mass ratio of the modified magnesium hydroxide to the mixed solvent is 0.01-0.5: 100.

2. The method of claim 1, wherein: the concentration of the dispersion A is 1-10g/L, and the concentration of the dispersion B is 0.1-5 g/L.

3. The method of claim 1, wherein: and (3) slowly dripping the dispersion liquid B at the normal temperature into the dispersion liquid A at the temperature of 60-75 ℃ during mixing, keeping the temperature at 60-75 ℃ after finishing dripping, reacting for 1-3h, filtering while hot, washing and drying to obtain the modified magnesium hydroxide.

4. The method of claim 3, wherein: washing with 60-75 deg.C alcohol solvent at 30-45 deg.C for 18-36 h.

5. The method of claim 1, wherein: the alcohol solvent is specifically absolute ethyl alcohol.

6. The method of claim 1, wherein: when the dispersion liquid A and the dispersion liquid B are mixed, the mass ratio of the magnesium hydroxide to the sodium phytate needs to be controlled within the range of 0.5-5: 0.05-2.5.

7. The method of claim 1, wherein: the modified magnesium hydroxide is uniformly dispersed in the mixed solvent through homogenization and ultrasonic treatment.

8. A paper deacidification agent based on sodium phytate modified magnesium hydroxide, characterized in that the deacidification agent is prepared according to any one of the methods in claims 1 to 7.