JPH07100920B2 - How to deoxidize library materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention Deterioration of paper, books and newspapers is well known and impressed by librarians and filers throughout the world. The causes of paper degradation are numerous and include intrinsic acidity, photodegradation, oxidation and microbial attack under certain conditions. These factors, coupled with the quality of the original paper, severely reduce the permanence of books and collections. Many other phenomena, such as floods, fires, and destruction of culture, inevitably add to these problems, but many insidiousness problems are the acidity of many papers in the last 100 years. Is becoming generally accepted.

The demand for large quantities of printing paper in the latest century results in the introduction of pulp fibers made from wood by chemical or mechanical means. However, paper made from untreated wood pulp was too absorbent to produce a sharp image imprint, so chemicals had to be added to the wood fibers during processing. These additives make the paper accept inks, dyes and increase the opacity of the paper. Unfortunately, many of these chemicals are acidic or are deposited by a mild acid mechanism that initiates mild but acidic acid degradation of the paper. Other contributions to paper acidification are provided by man by industrial emissions of sulfur, nitrogen, carbon oxides or by natural processes such as seawater spray. Even books or papers with neutral and alkaline properties are not exempt. When paper near its acidic nature degenerates, volatile acids diffuse through adjacent books or form by penetrating the atmosphere, eventually acidifying even "safe or stable" books.

To prevent this acid degradation, the paper material must be deacidified and applied with an alkaline pre- or buffering agent to delay the return to the acidic state. Current,
There are many methods in the development or commercialization of the various stages to deoxidize bound or unstitched paper.
Among these are the use of volatile metal alkyls such as U.S. Pat.Nos. 3,969,549 and 4,051,276 and volatile amines such as U.S. Pat.Nos. 3,472,611 and 3,7.
The methods of 71,958 and 3,703,353 are counted. 1972
U.S. Pat. No. 3,676,182, issued Jul. 11, 1993, discloses halogenated hydrocarbon solvents or optional plasticizers, such as lower aliphatic hydrocarbons such as n-butane (Col.7) with ethylene glycol (Col.9). , Cellulosic materials are treated with alkali and alkaline earth metal bicarbonates, carbonates and hydroxides (Col. 17). July 1972
U.S. Pat. No. 3,676,055 issued to Smith on the 11th treats a cellulosic material consisting of 1000 cc of 7% magnesium oxide (sic. Magnesium methoxide) in methanol and an additional 20 pounds of dichlorodifluoromethane (Freon 22). A non-aqueous deoxidizing solution is described. Smit
Canadian Patent No. 911,110, issued October 3, 1982, describes a deoxidation solution (p5) of 7% magnesium methoxide solution in methanol (10 parts) and halogenated solvent (90 parts); magnesium alkoxide. States that it reacts with water in paper to form magnesium hydroxide (p31), a mildly alkaline milk of magnesium. Improved results have been reported using halogenated hydrocarbon solvents (p40).

Unfortunately, all of these methods suffer from one or more of the many drawbacks that prevent them from being used extensively. These drawbacks include high cost, toxicity, processing complexity, residual odor, deleterious effects on certain papers and inks, and alkaline reserves.
This includes lack of ne reserve) and the need to dry the book or paper for very little moisture before processing.

SUMMARY OF THE INVENTION Acidic cellulosic materials can be treated with inexpensive, non-toxic materials that in some sense eliminate or minimize many of the problems of the prior art, including the need to dry the book or paper prior to processing. Was discovered. This method prints such paper (im
It can be used for cellulosic materials (paper) even when printed and / or spelled. In particular, books, paper and other materials with cellulosic materials are subject to the acidic pH of the material.
And a basic metal oxide, hydroxide or salt (hereinafter,
It has been discovered that it can be preserved by treating it with particles of alkaline material (referred to as alkaline or basic material). Even more surprisingly, it is not necessary to neutralize the acid present within the treatment period. Rather, an oxide, hydroxide or salt of a basic metal of suitable size is used as a cellulosic or paper web (wherein these particles gradually stop and neutralize the acidic compounds present or formed during aging). Web). These basic materials are also provided in the buffer in an amount sufficient for reoxidation due to other acidic effects while the paper is later stored.

The alkaline material is a material that is commonly available and is preferably selected from those that are relatively non-toxic. These particles are substantially colorless to image, colorless, and sized to provide good coverage. Submicron or near submicron particles are preferred as they can be suspended in a gas or an inert liquid, which eliminates the need for solutions or solvents that contribute to many of the drawbacks of current methods. Particles of these sizes are also closely supported within the paper matrix and do not loosen under normal use. Typical BET surface areas are in the range of 50-200 m ² / g which gives a high probability of acid contact and termination.

The present invention will be described in more detail.

DETAILED DESCRIPTION OF THE INVENTION Cellulosic materials can be treated with a suitable basic metal oxide, hydroxide or salt. Suitable materials are oxides, hydroxides, carbonates, bicarbonates of metals and zinc of Groups 1 and 2 of the Periodic Table. The cations are Mg, Zn, Na,
Materials that are K and Ca are preferred. Especially preferred are Mg and Zn.
Relatively non-toxic oxides, carbonates, bicarbonates and Na, K of
It is a hydroxide of Ca. Representative examples include magnesium oxide, magnesium carbonate, magnesium bicarbonate, zinc carbonate, zinc bicarbonate, zinc oxide, sodium hydroxide, potassium hydroxide, calcium hydroxide. Most preferred is magnesium oxide. The main particle size (95-99%) is 0.01-0.
9 microns is preferred, the average particle size is preferably 0.2-0.6 microns, and most preferably about 0.4 microns. Typical surface areas are 50 to 200 m ² / g BET, preferably about 170m ² / g
Is.

The particles are formed by grinding elemental metals and collecting smoke, by grinding preformed oxides or calcining elemental salts. For example, basic magnesium carbonate is calcined at 450-550 ° C to produce a polydisperse highly active magnesium oxide having an average particle size of 0.4 microns and a predominant particle size of 0.1-0.9 microns.

The particles are finished in the papermaking process or by electrostatic transfer, such as in xerography, by a dispersion in a gas or by a dispersion in an inert liquid.
ed paper). In the case of a liquid suspension of particles, the liquid chosen is preferably inert and has a vapor pressure high enough to be removed from the book or paper after exposure. A well suited liquid for this purpose is a halogenated hydrocarbon. Typical materials are Freon 11 (trichloromonofluoromethane), Freon 113 (1,1.2-trichloro-1,
2,2-trifluoroethane), DuPont Freon Fluorcarbons such as Freon 114 (1,2-dichloro-1,1,2,2-tetrafluoroethane) and Allied Chemical Getron (Allied Chemical Getron).
netron) 11 and 113 and mixtures. Suspensions are not susceptible to settling and / or flocculation if surfactants are used to overcome surface tension and charge traction effects. Typical materials are ICI Solsperse 6000 and 3
000 and 3M Fluorad FC740 and 741. Mixtures of these surface-active agents are used, the preferred surface-active agents being
A fluorinated alkyl ester known as Fluorad FC740.

The amounts of surfactant and alkaline material will depend in part on the length of treatment and the desired amount of deposition. However, in general, the concentration of alkaline material is about 0.01-0.3% and the surfactant is about 0.005.
~ 1.0%. The most preferred range for particles of basic material is about 0.01-0.2% and the most preferred range for surfactants is about 0.005-0.5%.

In the case of unspelled or single sheet paper, deposition occurs using a gas or air bearing dispersion. Active methods of deposition enhancement such as aerosol impaction, paper filtration and electrostatic attraction have been shown to be promising in increasing the rate of deposition. Impact of the gas-bearing dispersion on the paper in combination with electrostatic attraction is particularly effective. In this method, the paper is placed against a chargeable plate and the electric field thus created is used to attract particles to the paper.

The preferred method for spelled sheet material such as books or manuscripts is the use of suspensions in liquids. The liquid is used not only to disperse the particles to give a uniform treatment, but also to release the spelled material. The pages are easily separated and exposed to particles by the use of spray nozzles or the motion imparted to the spelled material while submerged. Liquid suspensions can produce high concentrations of particles in the treatment medium and deposit the required amount of alkaline material in a short time. By using a halogenated hydrocarbon-surfactant combination, stable concentrations of submicron particles range from 20-30 mg / ft ^{3 in} gas to 1-100 mg / ft ^{3 in} liquid.
Increase to ³ . At high concentrations, a single immersion in the treatment medium for a few seconds is sufficient to deposit the required amount of basic material. At low concentrations, two or more dips or long dips are required to achieve the same effect. After immersion, the inert liquid is evaporated, recovered and recycled.

The following examples serve to illustrate the invention.
All parts and percentages in the description and claims are:
Unless otherwise indicated, weight.

Example 1 The imaged acidic sheet of the sample was MgO powder (0.0
It was treated with an airborne dispersion with an average 0.4 micron particle size with a predominant particle size of 1-0.9 micron and a concentration of 25 mg / ft ³ . The sheets were placed in a glove box adapted to regulate humidity to 32% and the initial temperature was 22 ° C in standard atmosphere. Particles are Trost Air Mill (Air
Mill) and was transported to the glove box through a line connected to the discharge device. After 3 hours of exposure to the static air dispersion, the pH of the paper increased from an initial pH of 4.4 to 6.6 and the image was not harmed.

Example 2 50 samples of imaged acidic sheet of 3 samples with pH 4.3
It was dried in the oven for 1 hour at 0 ° C and then placed in a glove box under the conditions described in Example 1. The magnesium oxide dispersion in air as described in Example 1 was then pumped into the box and the container of warm water (40 ° C) was capped. The relative humidity went from 34% to 94% in 10 minutes, the water container was blocked after 10 minutes, and the dispersion treatment was interrupted at 1/2 hour. The moistening treatment of paper increased the deposition rate more than double that of Example 1. The sample sheet facing the dispersion has a pH of 7.2 to
It became 8.7.

Example 3 A paper sheet of imaged acidic book (pH 4.0) was placed in contact with the charged area of a static electricity generator (WINSCO Model N100-V). The stream of dispersed particles described in Example 1 was applied to the paper for about 5 seconds. After exposure, the pH of the paper was 8.5 and the image was not damaged.

Example 4 1000 ml of Allied Chemical Genetron containing 0.78 g (0.05%) of 3M Fluorad FC740 surfactant in the liquid treatment suspension.
3.2 g of MgO (500 g of basic hydromagnesite
(Calculated for 3 hours at 0 ° C.). This suspension was used to process a single sheet of acid book paper imaged by submerging each sheet in the suspension for 20 seconds. The sheets were then air dried and these sheets (40) with the same number of untreated sheets were subjected to accelerated aging by TAPPI standard T453m-48 for up to 28 days.
ageing). After removing the sample from the furnace, the folding endurance test value of the paper was measured using the MIT folding endurance tester (TAPPI standard T511su-69). The pH value was measured with a flat probe electrode according to TAPPI standard T529pm-74. The results are shown in the table below.

This paper came from a book 37 years ago.

Currently, the only method useful to measure the effect of treatment is to apply some type of accelerated aging, in this case paper to dry heating, and directly compare the strength retention of treated and untreated samples as described above. That is. The increase in life expectancy can be evaluated by converting the folding endurance test value to a logarithmic value and calculating a regression equation of treated and untreated paper with respect to the time of accelerated aging. The slopes of the resulting equation are then directly compared. This method, when applied to the above data, increased the life expectancy of treated paper by a factor of 2.5 over its untreated counterpart.

Example 5 The liquid suspension produced as in Example 4 was used for newsprint (6 years old) with a very high initial folding endurance value.
The paper employed from this book had an average pH of 5.0. After treatment as described in Example 4, the treated paper had an average pH of about 9.0. The results of accelerated aging are shown in the table below: Accelerated aging at 70 ℃ in water saturated atmosphere was done to show the effect of moisture during exposure. The acid hydrolysis was probably increased, although the paper gradually lost strength in the wet state, probably due to low temperatures. This is the pH before and after exposure
Indicated by a decrease in The pH of untreated paper dropped from 5.0 to 4.5 after 28 days in the drying oven, but dropped to 3.7 in the wet state. The treated sample remained at about pH 9.0 in the drying oven, but dropped to pH 6.6. After 28 days in the wet oven. These results show that the expected shelf life was nearly doubled with dry oven aging and slightly increased with wet oven aging. The sample was removed after treatment and the brittleness was measured again after 14 days of oven exposure. This was done when it was noticed that the treated samples appeared significantly whiter than the untreated samples after exposure to the oven. Brittleness measurement is TAPPI
Made according to standard T452. Untreated paper is brittle on average 73.7
From 12 to 65.6, a fragility of the treated sample of 74.4 to 65.6
It fell to 9.5, about 7%.

Example 6 A 30 gallon capacity tank was charged with 20 gallons of the processing suspension as described in Example 4. A spelled manuscript (average pH 3.9) featuring strong binding was placed at the spine of the book against the angle of a V-shaped metal tray (angle 90 ° C). The assemblage was weighed and dropped vertically into a suspension (the book spine perpendicular to the tank bottom). The bottom edge of the book block was approximately 1 inch above the bottom of the tank. A low impact, wide deflection, flat pattern spray nozzle was oriented to spray downward against the top edge of the book. Flow rate is 1.5
It was gallons / minute. The effect of the spray applied to the pages of the book was average. After 5 minutes, the book was removed and placed in a vacuum oven. The room is evacuated for 45 minutes, during which time about 100
% Fluorocarbon solution was collected in a freezing trap. A number of arbitrary pH measurements in the books showed values between 8.5 and 8.7. The indicator, bromocresol purple, was brushed on a few pages and it was shown that the method used produced excellent uniformity without image damage.

Example 7 In the tank used in Example 6, 0.3 g (0.02
%) Submicron magnesium oxide and 0.15g (0.01
%) Fluorad FC740 surfactant and 20 gallons of a suspension. A bound volume (average pH 4.1), characterized by having weak bonds, was fixed on the same V-shaped tray as described in Example 5. The assembly was lowered into suspension at the leading edge of the book facing upwards. After separating the book for 3 minutes, the book is gently placed in the suspension for 2 more minutes.
Moved up and down for a minute. Before removing the book, remove one cover,
The assembly was rotated 45 ° in the opposite direction from the free edge. When the book was pulled out of suspension, it closed freely with little or no pressure applied to the bond. After air drying, the pH changed from 6.1 to 7.3 without image damage.

Although the invention has been described using MgO, other alkaline materials are used in the same or similar amounts. Similarly, other surfactants and inert volatile liquids for dispersions will be apparent to those skilled in the art.

Claims (17)

[Claims] 1. A main particle size of 0.01-0.9 micron and a surface area of 50-200 m dispersed in a gas or in a liquid consisting essentially of an inert halogenated hydrocarbon and a surface-active agent. Appropriate alkaline particles of a basic metal selected from the group consisting of oxides, hydroxides and salts that are ² / gBET, increasing the pH of the material through the interstices of the imaged material and damaging its image. A sufficient amount and time to provide the alkaline buffer without the presence of the particles, if the particles are dispersed in a gas, by aerosol collisions, filtration by paper or by increased precipitation due to electrostatic attraction to form a book, image. A method of deoxidizing a material comprising treating paper and other imaged materials having a cellulosic material. 2. The method of claim 1 wherein the alkaline particles have an average particle size of 0.2 to 0.6 microns. 3. The method according to claim 1, wherein the basic metal is magnesium oxide. 4. The basic metal is magnesium carbonate, zinc carbonate, sodium carbonate, potassium carbonate, calcium carbonate,
The method of claim 1 which is a salt selected from the group consisting of sodium hydroxide, potassium hydroxide and calcium hydroxide. 5. The method according to claim 1, wherein the basic metal is a salt of calcium carbonate. 6. The method according to claim 1, wherein the basic metal is a salt of zinc carbonate. 7. The method according to claim 1, wherein the halogenated hydrocarbon is 1,1,2-trichloro-1,2,2-trifluoroethane. 8. The method of claim 1 wherein the concentration of basic metal is about 0.01-0.3%. 9. The method according to claim 1, wherein the concentration of the basic metal is about 0.01 to 0.2%. 10. The method according to claim 1, wherein the surfactant is a fluorinated alkyl ester. 11. The method of claim 1 wherein the particles are electrostatically moved toward the material. 12. The method of claim 1 wherein the aerosol is formed by particles in a gas. 13. A method according to claim 12 wherein the gas is selected from air, carbon dioxide, nitrogen and argon. 14. The method of claim 1 wherein the aerosol is formed of particles in air. 15. The method of claim 1 wherein the concentration of surfactant is between about 0.005 and about 1.0%. 16. The method of claim 1 wherein the concentration of surfactant is between about 0.005 and about 0.5%. 17. The method of claim 1 wherein the alkaline particles are applied at high humidity.