Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/18—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00 of old paper as in books, documents, e.g. restoring

Definitions

• the invention relates to a method for the conservation treatment of paper, in particular paper with a high addition of wood pulp, the material to be treated being soaked with a preserving solution and then dried again, and a device for carrying out such a method, with an impregnation arrangement for soaking the one to be treated Material with the preservation solution and a drying system.
• scientific libraries however, such papers and in particular newspapers must also be collected and kept as a time document.
• vapor phase and liquid phase processes are used in the previously known methods of the type mentioned, and in particular in those for mass preservation.
• the following technologies and processes are essentially known and - more or less successfully - in use: Impregnation with methoxy-magnesium methyl carbonate in freon plus methanol in a non-aqueous, liquid phase - this treatment leads to chemical deacidification of the paper, but this is not associated with an increase in the mechanical properties.
• the application is therefore only useful for mechanically undamaged or only slightly damaged papers.
• impregnation with diethylzinc in the vapor phase which is currently still being used on a trial basis and also does not permit mechanical re-reinforcement of the paper.
• impregnation is carried out with methyl methacrylate, ethyl acrylate and dimethylaminoethyl methacrylate in a non-aqueous, liquid phase and the paper treated in this way is then exposed to gamma rays.
• this also increases the mechanical properties of the paper by depositing a polymer in the paper fibers, it is only possible with very complex and relatively dangerous techniques.
• Another known method has been used for some time the paper to be treated is split up sheet by sheet and the waste paper layers impregnated with calcium hydroxide in the aqueous, liquid phase are then reapplied to a new carrier as the core material.
• the object of the present invention is to improve a method or a device of the type mentioned at the outset in such a way that the disadvantages of the known methods and arrangements mentioned are avoided and in particular the problems mentioned in connection with the drying of the paper treated with the preserving solution are held back can be.
• the paper to be treated is introduced into an at least largely evacuable chamber and covered with the preserving solution, the vacuum chamber is evacuated and then slowly ventilated again, the paper soaked with the preserving solution is shock-frozen, and the frozen paper is then freeze-dried.
• the aqueous solution can more easily penetrate into the interstices of the paper, but it has been shown that the actual impregnation essentially takes place only during the slow re-introduction of the air into the chamber is done.
• the subsequent shock freezing and freeze-drying ensure on the one hand that the otherwise quickly attacking and destructive mold growth which is otherwise quickly attacking and destroying the treated paper in the moist state is prevented with certainty due to the very short drying time and the drying parameters and on the other hand any sticking together of layers of paper, which are accidentally or deliberately on top of each other, by the preservation solution or is also excluded by any substances released from the paper.
• the aim should be to reach temperatures of around -30 -4 ° to -4 ⁇ ° C as quickly as possible so that only small ice crystals can form, since large crystals of this type could damage the nonwoven fabric of the treated paper.
• a number of stacked layers of paper in block form are each treated together in the manner described for mass preservation. For the first time and in a very simple manner, this enables large library or archive holdings to be treated conservatively, the process steps described above guaranteeing economical treatment while ensuring the quality of the end product.
• books after removing the cover
• newspapers and magazines loose or bound
• paper blocks of up to around 40 ⁇ 0 ⁇ sheets, or approx. 4 cm, still allowing perfect results.
• the impregnation under vacuum conditions described above ensures penetration of the paper block through the preservation solution, although of course due to the filtering effect of the paper fleece there is a certain concentration gradient of the various components of the solution towards the center of the block, but this has no demonstrable harmful effects on the end result.
• the Drying by sublimation is avoided by sticking the individual layers of paper or sheets together with the wet preservation solution.
• the drying time can be reduced to about one and a half days, which also prevents mold or the like from forming on the paper block.
• At least one insert part with free flow cross sections in particular made of plastic fabric or a corrugated and / or perforated metal or plastic plate, can be introduced into the block between individual paper layers.
• This insert part ensures that the preservation solution can penetrate quickly, even with thicker paper blocks, and thus better soak the block, as well as, of course, quicker and better drying.
• gaseous rinsing medium preferably air
• gaseous rinsing medium preferably air
• a preservative solution can be a mixture of water-soluble strengthening or resizing agent with a low viscosity, preferably based on cellulose ether, and water-soluble neutralizing agent, preferably based on Eradalkali compounds.
• Methyl cellulose preferably 1% strength, can be used as a setting or resizing agent Solution of MC 40 ⁇ or 0 ⁇ , 1 to 1% solution of MC 40 ⁇ 0 ⁇ and as neutralizing agent 0 ⁇ , 1% solution of calcium hydroxide can be used.
• the water-soluble cellulose ethers thus serve to strengthen the paper fibers, which is particularly important, for example, for newsprint with its approximately 80% wood pulp. Is used for highly absorbent sheets, such as newsprint, methyl cellulose MC 40 ⁇ 0 ⁇ , for less absorbent sheets MC 40 ⁇ or MC 50 ⁇ .
• the calcium hydroxide added to the preservation solution serves as neutralizing agent, which combines with the CO2 in the air during the drying process and then remains as CaCO3 as a permanent buffer against (so-called alkaline reserve) further acid formation in the paper web.
• the pH of the treated papers is increased significantly;
• the pH value of old newspapers is usually initially 3 to 5 - after the treatment described between 5 to 7 and higher.
• the preservation solution can additionally have penetration aids, preferably nonionic surfactants, added, which in particular makes the impregnation step more effective and faster.
• the evacuation of the vacuum chamber during the impregnation of the paper to be treated with the preservation solution can, according to a further development of the invention, be carried out in the pressure range of approximately 1 mb, the subsequent re-ventilation being extended to a time range of approximately one hour.
• a device for the preservative treatment of paper, in particular of paper with a high wood pulp, with an impregnation arrangement for impregnating the material to be treated with a preservation solution and a drying system is designed according to the invention in such a way that the impregnation arrangement has an evacuable chamber with at least one trough-like receiving element for the material to be treated and the layered preservation solution, and the drying plant has a shock freezer and a freeze-drying unit.
• the drying system can furthermore have a drying press upstream of the shock freezing cell with a drain device for the squeezed out, excess preservation solution.
• the device itself can either consist of three largely independent units (watering arrangement, blast freezer, freeze-drying unit) with manual or mechanical manipulation in between, or it can have an at least partial combination of these units, whereby due to the simplicity of the method described, quasi-continuous continuous operation is also possible is.
• the evacuable chamber of the watering arrangement is designed so that six separate paper blocks up to a format of 50 ⁇ x 70 ⁇ cm and a thickness of about 3 to 4 cm at the same time in a movable tub, whereby each block is still contained in its own plastic tub.
• the watering arrangement or its control is set up so that either the workflow "flooding with preserving solution - introducing the paper blocks - evacuating" or the sequence "introducing the blocks to be treated - evacuating - flooding with preserving solution” can be carried out.
• the first-described workflow is more effective since, among other things, there is less obstructive foaming of the methyl cellulose.
• various insert parts such as metal or plastic grids or mesh, can be inserted into the blocks.
• a plastic fabric which e.g. used as an oil filter in the petroleum industry has been found to be particularly useful because it does not deform the wet block of paper and quickly directs the preservative solution into the central part of the block. If the paper is not very absorbent, two or more of these insert parts can also be inserted at different heights of the stack.
• a stick press with a drainage device is used as the drying press in the device designed, with which the excess of preservation solution is removed after the vacuum impregnation has been completed.
• the pressed cellulose is gray-brown, which results from its function as a "dirt carrier” and results in a certain cleaning of the treated papers.
• the freeze-drying unit used allows the thirty batches (blocks of paper) to be transferred directly from the blast freezer.
• the device which was designed for the pharmaceutical industry, was modified for the present purpose, whereby the ice capacity was increased from 10 ⁇ 0 ⁇ kp to 160 ⁇ kp. Because of the poor thermal conductivity of paper, the drying process is initially very slow. This process can be accelerated, inter alia, by carrying out discontinuous air or gas injections in order to remove the water vapor produced during sublimation more quickly.
• the blocks can be pressed if necessary and then archived or used again.

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Cited By (8)

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• 1986
  • 1986-12-30 AT AT345986A patent/AT391721B/de not_active IP Right Cessation
• 1987
  • 1987-12-28 EP EP87890296A patent/EP0273902A3/fr not_active Withdrawn

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