CN102268842B - Method for deacidifying paper by using soluble tetraborate as paper deacidifying agent - Google Patents

Abstract

The invention discloses a method for using soluble tetraborate as a paper deacidification agent for paper deacidification. The aqueous solution of tetraborate with different concentrations is mixed with different types of organic solvents, and the method is soaked, sprayed, atomized or supercharged. Critical treatment and other ways to deacidify paper, especially acidified and aged paper; soluble tetraborate is used as paper deacidifier for deacidification, which can control the pH value of paper in an ideal range, and the process of deacidification It does not cause the diffusion of ink and the discoloration of paper, and enhances the mechanical strength of paper while deacidifying. Tetraborate also provides a certain effect of inhibiting microorganisms. After being treated with tetraborate solution, the durability of paper is improved. Significantly improved.

Description

The method that soluble tetraborate is used as paper deacidification agent for paper deacidification

technical field

The invention relates to a method for using soluble tetraborate to deacidify paper, such as ancient book paper; in particular, it relates to a method for using soluble tetraborate as a paper deacidifier for paper deacidification. the

Background technique

Chinese culture has a long history and is dazzling. It is estimated that there are as many as 80,000 kinds of Chinese ancient books and documents since the "Oracle Bone Inscriptions" were recorded. "Ancient books" is the abbreviation of ancient Chinese books, the main carrier and representation of human material civilization and culture, and a rich historical and cultural heritage left to us by the splendid civilization history of the Chinese nation for 5,000 years. However, many precious ancient books are damaged to varying degrees due to the age, wars and funerals, water and fire invasion, rat gnawing and moth erosion, and environmental deterioration, and most of the ancient books are damaged to varying degrees, and they are in urgent need of protection and rescue. According to statistics, there are about 1.4 million ancient books in the National Library of Ancient Books. However, due to the age, some precious and rare books handed down from generation to generation are also riddled with holes and incomplete. In today's time, the ancient books handed down from generation to generation are more and more precious. Among the 1.4 million volumes of ancient books, about 30% are slightly damaged, 10% are moderately damaged, and 10% are severely damaged. The sum of the three items is nearly half, especially the ancient books of the Republic of China period, the damage is even more serious. Due to the backwardness of papermaking technology in the period of the Republic of China, the acid content of the paper was high, and the pH value of a considerable number of thread-bound books in the Republic of China was below 3. The paper had already undergone severe acidification and mildew, and lost the mechanical strength that paper should have. It was on the verge of destruction. Therefore, how to protect these precious ancient books and documents is an urgent and arduous task before us. the

The types of damage to ancient books include insects, mildew, flocculation, rat bites, fire embers, paper aging, acidification, etc., and acidification and aging are a continuous process. Therefore, if these ancient books cannot be effectively treated at present, they must be It will continue to spread, even irrecoverable. Acidification of ancient books refers to the phenomenon that the acidity of ancient book paper gradually increases. The specific manifestation is that the paper becomes brittle, the color becomes yellow, dark, and the mechanical strength is reduced. In serious cases, it will not be able to be turned, or even broken into paper scraps. Among the damaged paper, the damage caused by acidification to ancient books accounts for a considerable proportion, and will seriously affect the preservation life of ancient books. If the pH value of ancient books and documents is lower than 6.2, it should be deacidified; if it is lower than 5.0, it must be deacidified. The harm caused by acidification of paper has attracted the attention of governments of various countries. In recent years, countries have carried out deacidification treatment of paper cultural relics. According to experiments, books with paper pH below 5.0 can be stored for up to 200 years. As long as the paper contains acid, even if the ancient books and documents are only hidden or in a good preservation environment, the qualitative change of the paper cannot be inhibited. the

Acidification is the main factor for the degradation of ancient paper. When restoring ancient books, alkaline compounds are added to increase the pH value of the paper to neutral or above, that is, "deacidification", thereby blocking the acidic hydrolysis of cellulose to achieve protection. The purpose of paper avoiding damage. Therefore, it is very important to find a deacidification agent suitable for deacidification of paper, so as to minimize the impact on paper appearance while achieving a good deacidification effect. the

At present, the deacidification agents commonly used in paper deacidification include calcium hydroxide, calcium bicarbonate, calcium propionate, magnesium bicarbonate, barium hydroxide-methanol solution, magnesium oxide, magnesium-titanium double metal alkoxide, methoxymethyl carbonate Magnesium, ethoxyethylmagnesium carbonate, methylmagnesium carbonate and ethylmagnesium carbonate, etc.

The pH value of the paper after the deacidification treatment of the calcium compound is obviously increased, the whiteness value is also increased correspondingly, and the alkali retention value is increased. The improvement of these physical and chemical performance indicators will extend the preservation life of the document for more than 100 years, and the calcium-containing compound deposited on the paper will slow down the pollution of acid gas in the air. However, the saturated solutions of calcium hydroxide and calcium bicarbonate are highly alkaline, which is not suitable for the neutral treatment of modern paper. the

After the water-soluble compound of magnesium is deacidified, the pH value of the paper can reach 9.4-10.4, and the residual amount of alkali is 2.0%. The excess will be naturally adsorbed on the surface of the paper, and MgCO ₃ will be generated as an alkaline residue to act as a buffer, and can resist the erosion of acidic substances for a long time. However, the pH of the paper after the deacidification treatment is relatively high, and it is not suitable for paper with a weight exceeding 140g/m2, large-format paper, photos, zinc oxide copies, and embrittled paper, and has relatively large limitations. The paper aging test shows that the mechanical strength of the paper is reduced, and the paper turns yellow seriously.

Among the non-aqueous deacidification agents, the barium hydroxide-methanol solution will spread the handwriting after deacidification; methoxymethyl magnesium carbonate has uneven deacidification, handwriting fading, white spots, wrinkling and discoloration, and adhesive oozing And other problems, so there are certain limitations; Ethoxyethyl magnesium carbonate helps to improve the durability of paper and delay aging, but there are also paper discoloration, white precipitates, Newton rings, and fading of handwriting. And diffusion, there are some unpleasant smells, the paper feels different after treatment, and the acid removal effect is uneven. Magnesium alkoxide has the disadvantages of relatively harsh preparation conditions and complicated process, and it will damage books to varying degrees. The treated books may absorb water faster, have obvious discoloration, and yellow and translucent stains appear at the same time. Not suitable as a large-scale deacidification agent. the

Deacidification of paper has been carried out for decades, and there is no report on the use of tetraborate for deacidification, which shows that those skilled in the art cannot simply deduce that tetraborate can be used for deacidification from the existing deacidification agent materials. Borates include metaborates, orthoborates, and polyborates. The most important borate is sodium tetraborate in tetraborate, commonly known as borax (Na ₂ B ₄ O ₇ 10H ₂ O), which can be used as disinfectant, fresh-keeping preservative, water softener, eyewash, soap additive , Ceramic glazes and glass raw materials, etc. Borax also plays an important role in industrial production. Tetraborate, which has some similar properties to sodium tetraborate, has two SP ² hybridized BO ₃ planar triangles and two SP ³ hybridized BO ₄ tetrahedrons in the borate group by sharing the corner O atoms. link up. In the aqueous solution of tetraborate, there is the following hydrolytic equilibrium:

Because of this hydrolytic equilibrium, aqueous tetraborate solutions can be used as pH calibration solutions. Since the pH of the saturated tetraborate aqueous solution is about 9.24, it can effectively avoid the problem that the solution is too alkaline and the alkali residue does not meet the standard. In addition, the SP ² electron-deficient structure in the borate makes the tetraborate have a strong electron-withdrawing ability, and it is easy to add polyols to enhance the ability of the intermolecular force; in addition, due to the special electron-deficient structure of the boride , so that its compounds have a variety of special properties, and are often used as modifiers in industrial production, but there is no application related to deacidification or strengthening of paper.

Contents of the invention

The invention provides a method for using soluble tetraborate as a paper deacidification agent for deacidification of paper.

The technical solution of the present invention is that the soluble tetraborate used as a paper deacidification agent refers to a tetraborate with a solubility greater than 0.002g/ml in a solvent at a room temperature of 20°C, and the soluble tetraborate is a soluble Tetraborate or a mixture of several soluble tetraborates, soluble tetraborate can optionally be mixed with other deacidification agents; the aqueous solution of paper deacidification agent and different types of organic solvents in a volume ratio of 100: 0～10:90 mixing, the mass concentration range of the above-mentioned paper deacidifying agent aqueous solution is 0.005%～saturated, the amount of paper deacidifying agent is 0.001～10 times of the paper mass, and the contact time between deacidifying agent solution and paper is 0.2～5h. the

As mentioned above, the organic solvent used is one or more of methanol, ethanol, propanol, isopropanol or glycerin. the

As mentioned above, the way of using the deacidification agent to implement deacidification includes soaking, spraying, atomization or supercritical fluid deacidification and all deacidification actions that make the soluble deacidification agent contact with the paper. the

As mentioned above, the processed paper can be modern paper and ancient paper, and the processing volume can be single-page paper or multi-page paper or books. the

In the above-mentioned method, the preferred mass concentration range of the above-mentioned paper deacidifier is 0.14 to 3.52%, the preferred amount of the paper deacidifier solution is 0.005 to 10 times the paper mass, and the preferred contact time between the deacidifier solution and the paper is 0.6~2.5h, the organic solvent used is preferably ethanol, and the volume ratio of water to ethanol is preferably 90:10~30:70

The above-mentioned method is characterized in that the above-mentioned several soluble tetraborates are lithium tetraborate, sodium tetraborate, potassium tetraborate or calcium tetraborate. the

The invention utilizes the property that soluble tetraborate can be hydrolyzed in aqueous solution and is used as a pH buffering agent, and neutralizes acidic substances in paper after mixing its saturated aqueous solution with different types of organic solvents according to a certain volume ratio. In the process of deacidification, the tetraborate solution can not only effectively control the pH value of the paper in the ideal range, that is, neutral to 8.5, but also has good alkali residue; in the aging experiment, the treated paper slowed down the pH of the paper. The further acidification of the paper plays a protective role in the long-term storage of the paper. the

The invention utilizes the typical electron-deficiency of tetraborate, that is, it has strong ability to accept electrons and is easy to self-polymerize, form complexes, add to polyhydroxy compounds, and the like. In the process of contacting with paper, it can combine with the hydroxyl group of cellulose molecules, increase the force between cellulose molecules, and improve the strength of paper to a certain extent. the

The method provided by the present invention for deacidifying modern books or ancient books by using soluble tetraborate does not cause a large change in the chromaticity of the appearance of the paper, and the tetraborate is not easy to react with some colored groups that are easily oxidized in the paper , so the color of the paper did not change significantly. the

The soluble tetraborate used in the invention also has a certain antibacterial property, can inhibit the growth of microorganisms, and protects the paper to a certain extent. the

Although the embodiment of the present invention only enumerates several kinds of tetraborates, the tetraborates that can be used for paper deacidification are not limited to these four borates. Those skilled in the art can according to the principles of the present invention Paper deacidification using all soluble tetraborates. the

Although the present invention only selects the cheapest newspaper for paper deacidification, this technology is not limited to deacidification of newspaper. Both newspapers and books are a way of recording text information using paper as a carrier. The bound volume of newspapers is different from books only in size. the

The present invention realizes by following scheme:

Take tetraborate aqueous solution with mass concentration ranging from 0.005% to saturation concentration (preferably 0.14 to 3.52%) and mix different types of organic solvents according to a certain volume ratio, and the ratio is 100:0 to 10:90 (preferably 90:10~30:70), using deacidification methods such as soaking, spraying, atomization or supercritical fluid, after 0.2~5h (preferably 0.6~2.5h), according to the amount of deacidification agent solution is 0.001 of the paper mass ~10 times (preferably 0.005~10), acting on the acidified ancient book paper to neutralize the acidic substances in the paper, and the pH value of the paper after deacidification is 7.1~8.5. The deacidified paper was baked at 105°C for 72 hours (equivalent to 25 years under natural conditions), and artificial aging simulation experiments were carried out to detect the maintenance of its pH and strength.

Deacidification agents include all soluble tetraborates such as borax (Na ₂ B ₄ O ₇ 10H ₂ O), Na ₂ B ₄ O ₇ 5H ₂ O, Li ₂ B ₄ O ₇ (anhydrous), K ₂ One or more of B ₄ O ₇ , CaB ₄ O ₇ and other tetraborates; the solvent used is but not limited to one or more of methanol, ethanol, propanol, isopropanol, glycerin and water The mixture (preferably water or ethanol or a mixture of water and ethanol) can be any solvent capable of dissolving the deacidification agent and its mixture.

The beneficial effects of the present invention are:

1. Use soluble borate solution as the deacidification agent for paper. After deacidification, the pH value of the paper can be controlled in an appropriate range, that is, between 7.1 and 8.5. After deacidification, the paper has a moderate alkalinity and has a good effect on the paper The deacidification effect; because the pH value of the saturated tetraborate aqueous solution is less than 9.30, the further alkaline hydrolysis of cellulose caused by the high pH value is avoided.

2. Using soluble tetraborate solution as a deacidification agent, it is not easy to react with some chromophoric groups in the paper. After deacidification treatment, the chroma of the paper does not change significantly. the

3. Boron has a special electron-deficient configuration and can form electron-deficient compounds. Tetraborate is a typical electron-deficient compound, which has a strong ability to accept electrons, and has the ability to easily undergo self-polymerization, form complexes, and add to polyhydroxy compounds. In the process of contacting with paper, it can combine with the hydroxyl group of cellulose molecules, increase the force between cellulose molecules, and improve the strength of paper to a certain extent. the

4. When studying the retention of deacidification agent, through the artificial aging simulation experiment, after drying at 105°C for 72 hours (equivalent to 25 years under natural conditions), the pH value and strength of the paper after aging were tested, and the paper was kept in good condition. . the

5. Tetraborate also has certain antibacterial properties, which is beneficial to the long-term preservation of paper. the

specific implementation plan

The use method of the present invention will be further elaborated below by implementing examples. the

The experiment uses the New York Times newspaper in 1989, and its performance parameters are listed in the following table: pH Tensile strength (KN/m) Elongation(%) Tear degree mN) Folding endurance (times) 3.23 1.72 0.87 122.0 5

Example 1

Take about 130g of the New York Times newspaper in 1989 and put it into a container of appropriate size. Mix the saturated aqueous solution of sodium tetraborate and ethanol at a volume ratio of 80:20 at a room temperature of 25°C. Take 850ml of the aqueous alcohol solution and soak Treat for 40 minutes to neutralize the acidic substances in the paper. The pH of the paper after deacidification is 8.46; the tensile strength is 1.82, which is 5.8% higher than that before deacidification; the elongation is 1.39, which is 59.8% higher than that before deacidification; the tearing degree is 146.8, which is higher than that before deacidification 20.3%; the folding strength is 7, which is 40% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

The comparison of performance parameters of paper before and after deacidification and after aging is shown in the table below: pH tensile strength Elongation% Tear degree mN Folding Endurance After deacidification 8.46 1.82 1.39 146.8 7 after aging 8.02 1.71 1.11 135.2 4

Example 2

Take about 207g of New York Times newspaper in 1989, put it into a container of appropriate size, and mix tetraborate (sodium tetraborate, potassium tetraborate, calcium tetraborate, etc.) saturated aqueous solution with ethanol according to the volume ratio Mix evenly at a ratio of 80:20, take 1200ml of alcohol water solution, soak for 40min, and neutralize the acidic substances in the paper. Take the deacidification agents listed in the table below, mix them with ethanol according to the same solvent volume ratio, and use the same conditions to treat the same amount of paper as a reference. From the comparison of deacidification results, it can be seen that the deacidification effect using borate is significantly better than other types of deacidification agents listed in the table below. After aging at 105℃ for 72 small tests, the strength remains good.

The comparison of performance parameters of paper before and after deacidification and after aging is shown in the table below: Na ₂ B ₄ O ₇ K ₂ B ₄ O ₇ CaB ₄ O ₇ CaCO ₃ Ca(C ₂ H ₅ COO) ₂ Ca(OH) ₂ MgCO ₃ Mg(HCO ₃ ) ₂ Mg(OH) ₂ pH 8.33 8.38 7.32 6.75 6.84 9.12 6.70 6.71 6.78

Example 3

Take about 110g of the New York Times newspaper in 1989, put it into a container of appropriate size, and mix the saturated aqueous solution of sodium tetraborate, the aqueous solution of potassium tetraborate and ethanol at a room temperature of 25°C in a ratio of 25:25:50 by volume. , take 950ml of alcohol aqueous solution, soak for 40min, and neutralize the acidic substances in the paper. The pH of the paper after deacidification is 8.24; the tensile strength is 1.99, which is 15.7% higher than that before deacidification; the elongation is 1.21, which is 68.1% higher than that before deacidification; the tearing degree is 142.0, which is higher than that before deacidification 16.4%; the folding strength is 8, which is 60% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 4

Take about 211g of New York Times newspaper in 1989, put it into a 2L atomization device, and mix potassium tetraborate saturated aqueous solution and calcium tetraborate saturated aqueous solution with ethanol at a volume ratio of 40:20:40 at a room temperature of 25°C Mix evenly, take 1500ml of alcohol water solution, inject the mixed solution from the atomizer, and treat for 1.5h to neutralize the acidic substances in the paper. The pH of the paper after deacidification is 8.19; the tensile strength is 2.24, which is 30.2% higher than that before deacidification; the elongation is 1.24, which is 41.7% higher than that before deacidification; the tearing degree is 145.5, which is higher than that before deacidification 19.3%; the folding strength is 8, which is 60% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 5

Take about 240g of New York Times newspaper in 1989, put it into a 2L atomization device, mix the saturated aqueous solution of calcium tetraborate and ethanol at a volume ratio of 65:35 at a room temperature of 25°C, and take 1800ml of alcohol aqueous solution , inject the mixed solution from the atomizer, and treat for 1.5h to neutralize the acidic substances in the paper. The pH of the paper after deacidification is 7.59; the tensile strength is 2.23, which is 29.7% higher than that before deacidification; the elongation is 1.33, which is 52.9% higher than that before deacidification; the tearing degree is 192.8, which is higher than that before deacidification 58.0%; the folding strength is 14, which is 180% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 6

Take about 187g of New York Times newspaper in 1989, put it into a container of suitable size, and mix saturated aqueous solution of lithium tetraborate, saturated aqueous solution of sodium tetraborate and ethanol at a volume ratio of 30:30:40 at a room temperature of 25°C Evenly, take 1000ml into a watering can, spray the paper for 1 hour, and neutralize the acidic substances in the paper. The pH of the paper after deacidification is 8.47; the tensile strength is 1.95, which is 13.4% higher than that before deacidification; the elongation is 1.32, which is 51.7% higher than that before deacidification; the tearing degree is 152.0, which is higher than that before deacidification 24.6%; the folding strength is 8, which is 40% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 7

Take about 301g of the New York Times newspaper in 1989, put it into a suitable size container, mix the saturated sodium tetraborate aqueous solution and ethanol at a room temperature of 25°C in a ratio of 75:25 by volume, take 2400ml and put it into a watering can, Spray the paper for 1 hour to neutralize the acidic substances in the paper. The pH of the paper after deacidification is 8.19; the tensile strength is 2.02, which is 17.4% higher than that before deacidification; the elongation is 1.38, which is 58.6% higher than that before deacidification; the tearing degree is 146.0, which is higher than that before deacidification 19.7%; the folding strength is 8, which is 60% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 8

Take about 169g of the New York Times newspaper in 1989, put it into a 2L supercritical CO2 treatment kettle, and inject the entrainer saturated aqueous solution of sodium tetraborate and aqueous solution of calcium tetraborate-ethanol ( 45:40:15), a total of 1000ml solution, 2.5h of treatment, the flow rate of CO2 fluid is 0.002t/h. The pH of the paper after deacidification is 8.03; the tensile strength is 2.32, which is 34.9% higher than that before deacidification; the elongation is 1.26, which is 44.8% higher than that before deacidification; the tearing degree is 184.8, which is higher than that before deacidification 51.5%; the folding strength is 10, which is 100% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 9

Take about 174g of the New York Times newspaper in 1989, put it into a 2L supercritical CO2 treatment kettle, and inject the entrainer potassium tetraborate saturated aqueous solution-ethanol mixed solution (volume ratio: 80:20) 1200ml, treatment for 3.5h, the flow rate of CO2 fluid is 0.002t/h. The pH of the paper after deacidification is 8.19; the tensile strength is 2.14, which is 24.4% higher than that before deacidification; the elongation is 1.23, which is 41.4% higher than that before deacidification; the tearing degree is 192.8, which is higher than that before deacidification 58.0%; the folding strength is 12, which is 140% higher than that before deacidification. After aging, the pH and strength remain good, and the deacidification effect is good.

Example 10

Take about 216g of the New York Times newspaper in 1989, put it into a 2L supercritical _CO2 treatment kettle, and under the condition of 25MPa and 36°C, inject the entrainer potassium tetraborate saturated aqueous solution-ethanol mixed solution (volume ratio 60:40) 1600ml, treatment for 4h, the flow rate of CO ₂ fluid is 0.002t/h. After supercritical _CO2 treatment, the pH value of the paper was 8.38, and the pH retention was good after aging; the tensile strength of the paper was 2.72, which was 58.2% higher than that before deacidification; the elongation was 1.57, which was 80.4% higher than that before deacidification, The tearing degree is 195.2, which is 60% higher than that before deacidification; the folding resistance is 14, which is 180% higher than that before deacidification; the strength remains good after aging at 105°C for 72 small tests.

Example 11

Take about 108g of the New York Times newspaper in 1989, put it into a 2L supercritical _CO2 treatment kettle, and under the condition of 24MPa and 39°C, inject the entrainer from the auxiliary pump, each sodium tetraborate saturated aqueous solution-ethanol mixed solution (The volume ratio is 50:50) 700ml, the treatment time is 1.4h, and the flow rate of CO ₂ fluid is 0.002t/h. After supercritical treatment, the pH value of the paper was 8.33, and the pH retention was good after aging; the tensile strength of the paper was 2.70, which was 56.9% higher than that before deacidification; the elongation was 1.54, which was 77.0% higher than that before deacidification; the tear The strength is 204.2, which is 67.2% higher than that before deacidification; the folding resistance is 13, which is 160% higher than that before deacidification; the strength remains good after aging at 105°C for 72 small tests.

Example 12

Take about 114g of the New York Times newspaper in 1989, put it into a 2L supercritical _CO2 treatment kettle, and inject the entrainer mixed solution of potassium tetraborate saturated aqueous solution and ethanol (volume ratio 50:50) 1000ml, treatment 2h, the flow rate of CO ₂ fluid is 0.002t/h. Take the deacidifying agent with the same ratio and volume, and use the spraying method to treat the paper with the same quality as a reference. After supercritical treatment, the pH value of the paper was 8.49 (spray method 8.20), and the pH retention was good after aging; the paper tensile strength was 2.82 (spray method 2.44), which was 63.9% higher than before deacidification; the elongation was 1.49 (spray method method 1.42), 77.0% higher than before deacidification; tearing degree 199.7 (spray method 171.2), 63.7% higher than before deacidification; folding resistance 14 (spray method 11), 180% higher than before deacidification %; After aging, the strength remains good, and the retention effect is better than that of the soaking method.

Example 13

Take about 149g of the New York Times newspaper in 1989, put it into a 2L supercritical _CO2 treatment kettle, and under the condition of 21MPa and 38°C, inject the entrainer mixed solution of sodium tetraborate saturated aqueous solution and ethanol from the auxiliary pump (volume Ratio 75:25), a total of 750ml solution, treatment for 1.5h, the flow rate of CO ₂ fluid is 0.002t/h. Take the deacidifying agent with the same ratio and volume, and use the spraying method to treat the paper with the same quality as a reference. After supercritical treatment, the tensile strength of the paper is 2.82 (spray method 2.44), which is 63.9% higher than before deacidification; the elongation is 1.46 (spray method 1.21), which is 67.8% higher than before deacidification; tearing degree is 184.2 (spraying method 151.2), which is 51.5% higher than before deacidification; folding resistance is 12 (spraying method 8), which is 140% higher than before deacidification; after aging, the strength remains good, and the retention effect is better than soaking method.

Claims (8)

1. A kind of method that soluble tetraborate is used for paper deacidification as paper deacidification agent, it is characterized in that: the soluble tetraborate as paper deacidification agent refers to solubility greater than 0.002g in the solvent when room temperature 20 ℃ /ml of tetraborate, the soluble tetraborate is a soluble tetraborate or a mixture of several soluble tetraborates, the soluble tetraborate can optionally be mixed with other deacidification agents The aqueous solution of paper deacidifier is mixed with different types of organic solvents in a volume ratio of 100:0 to 10:90. The mass concentration range of the above-mentioned paper deacidifier aqueous solution is 0.005% to saturation, and the amount of paper deacidifier is 1% of the paper quality 0.001 to 10 times, and the contact time between the deacidifying agent solution and the paper is 0.2 to 5 hours. 2. The method according to claim 1, characterized in that: the organic solvent used is one or more of methanol, ethanol, propanol, isopropanol or glycerin. 3. The method according to claim 1, characterized in that: the above-mentioned paper deacidification agent is implemented in a deacidification manner including soaking, spraying, atomization or supercritical fluid deacidification, which makes this soluble deacidification agent contact with paper. sour behavior. 4. The method according to claim 1, characterized in that: the processed paper is modern paper or ancient paper. 5. The method according to claim 1, characterized in that: the processed paper is a single sheet or multiple sheets. 6. The method according to claim 1, characterized in that: the mass concentration range of the above-mentioned paper deacidifier is 0.14 to 3.52%, and the amount of the paper deacidifier solution is 0.005 to 10 times that of the paper mass. Paper contact time is 0.6 ~ 2.5h. 7. The method according to claim 1, characterized in that: the organic solvent used is ethanol, and the volume ratio of the paper deacidification agent aqueous solution to ethanol is 90:10-30:70. 8. The method according to claim 1, characterized in that: above-mentioned several soluble tetraborates are lithium tetraborate, sodium tetraborate, potassium tetraborate or calcium tetraborate.