EP0542966A1

EP0542966A1 - Process and device for mass conservation of archives.

Info

Publication number: EP0542966A1
Application number: EP92911703A
Authority: EP
Inventors: Guenther Dr Schwarz
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-06-04
Filing date: 1992-06-03
Publication date: 1993-05-26
Anticipated expiration: 2012-06-03
Also published as: ATE137831T1; WO1992021817A1; DE4118249C2; AU1896292A; DE4118249A1; US5421945A; DE59206229D1; EP0542966B1

Abstract

PCT No. PCT/EP29/01229 Sec. 371 Date Feb. 1, 1993 Sec. 102(e) Date Feb. 1, 1993 PCT Filed Jun. 2, 1992 PCT Pub. No. WO92/21817 PCT Pub. Date Dec. 10, 1992.The mass preservation of archives by melting on them a binder combination reinforced with a nonwoven or woven fabric, in which a woven or nonwoven fabric on a supporting belt or supporting roller is impregnated with an aqueous, pollutant-free, self-cross-linking and/or not self-cross-linkable and/or pre-cross-linked dispersion, free of volatile solvents, of a thermoplastic binder with a high film-forming temperature above 60 DEG C., into which dispersion waxes or paraffins, with a concentration-based on the solids portion of the dispersion-of 3 to 10% by weight have been incorporated by hot precipitation, dried and, in conjunction with the substrate that is to be preserved, fused under the action of pressure and temperature by a brief temperature shock at a temperature appreciably exceeding the film-forming temperature to a substrate-sealing film with embedded nonwoven or woven fabric.

Description

Method and device for the mass preservation of archives

The invention relates to a method for the mass preservation of archives by preferably melting on both sides of a binder combination reinforced by a nonwoven or woven fabric.

Recently, due to alarming reports from all libraries and archives, great efforts have been made to save the printed and written works that are on the verge of disintegration, which, besides wear and tear due to use, are particularly threatened by the temporary durability of the paper.

The reason for the low durability of modern papers in particular is sulfuric acid and acid-forming ingredients, which have been used in industrial paper production since 1850. Unfavorable storage conditions such as heat, high air humidity and climate fluctuations accelerate the decay.

In order to preserve these archival documents with papers from around 1850, a number of chemical processes have been proposed which consist essentially in exposing the archival documents to a gaseous or liquid neutralizing agent in order to neutralize the acid components to prevent further destruction in the paper. This can prevent further disintegration, but the previous, perfect condition of the paper cannot be restored. In particular, the brittleness of the paper that has occurred remains even after such neutralization. In any case, extensive deacidification

£ R $ ATZBJ VΓΓ rich technical systems are required, which can only be built at a central location and operated by specially trained personnel, so that the archive material for treatment must be transported to such central locations, which means that the risk of damage to the brittle archive material during transport is very considerable is increased. Furthermore, these processes are also very expensive and, as I said, are of no use at all in cases in which the disintegration of the paper has progressed to such an extent that the neutralized and deacidified paper can no longer be used due to the fragility that has arisen is possible.

In addition, attempts have of course also been made to consolidate the paper which has become fragile due to the acid decay, but so far only manual methods have been available for this, but not suitable for mass preservation.

At present, the fixing is carried out by hand by using polyethylene film as an adhesive layer in conjunction with fleece at a relatively long pressing time (5 to 6 minutes) and relatively high temperatures (120 ° Celsius). The result is anything but optimal. The printed image is blurred and the high press temperature in connection with the relatively long press time very much affects the archive material to be restored.

The invention is therefore based on the object of developing a method for mass preservation using plastic layers which are preferably melted on both sides in such a way that, with the greatest possible environmental friendliness, it is quick and easy without any great equipment Effort can be carried out, so that it is in particular also possible to use the method decentrally even in smaller archives. In addition, the printed image should neither be obscured, nor should the recognizability be impaired in any other way.

To achieve this object, it is provided according to the invention that nonwoven or fabric with an aqueous, pollutant-free, self-crosslinking and / or externally crosslinkable and / or pre-crosslinked dispersion free of volatile solvents of a thermoplastic binder with a high, above, on a carrier tape or a carrier roller 60 ° C film formation temperature, into which waxes or paraffins with a concentration - based on the solids content of the dispersion - of 3 to 10% by weight have been incorporated, soaked and dried and in connection with the substrate to be preserved is melted together under the action of pressure and temperature by a brief temperature shock at a temperature significantly exceeding the film formation temperature to form a film sealing the substrate with embedded fleece or tissue.

The method according to the invention provides a very simple way of strengthening the archival material with maximum transparency and adhesion between the applied sealing film and the substrate. In addition, the double-sealed substrate is still a thin film, which is therefore only a little thicker than the original substrate itself, which is again completely flexible, even if a completely brittle substrate was present beforehand. Due to the combination according to the invention of a method for producing quick-curing coatings from carrier bodies according to the patent specification DE 38 02 797 embedded with the use

REPLACEMENT LEAF Tied nonwovens provide an extremely easy-to-use sealing option for archival documents. The short temperature shock according to the invention has the very decisive advantage that only the coating that is actually to be melted into a film is heated and not, for example, also the carrier material, that is to say the substrate to be preserved. This means that the substrate is not impaired at all, especially if, after the film has been melted together, cooling is again provided from the outside, so that the heat contained in the layer is also removed again before it re-occurs can be delivered to the inside of the substrate.

The process according to the invention, in which nonwovens made of cellulose fibers or glass fibers or plastic fibers or carbon fibers or of course also mixtures of such fibers can be used, preference being given to using ultrathin nonwovens, also offers the advantage that by adjusting the binder films to a pH greater than 7, the acid content can also be neutralized simultaneously with the decisive mechanical solidification of the substrates, so that further decompositions can no longer take place. With the method according to the invention, it is then no longer necessary, as previously, to deacidify the paper with the aid of the methods which have already been developed for this anyway and a subsequent, also very complex and unreasonable consolidation, but one can do it quickly and rationally feasible melt coating processes with incorporated reinforcement fleeces simultaneously accomplish deacidification and consolidation. For example, solvent-free alkalis which do not split off pollutants can be added to these binder combinations. In addition, the addition of epoxidized oils or also 4-tertiary-butyl-catecholate to prevent further breakdown of the cellulose fiber.

It has been shown that the binders provided according to the invention have a high melting point or high minimum film-forming temperature (MFT) and can be applied in a conventional manner, for example by rolling, knife coating, spraying, filling, pouring or electrostatic spraying , if they are exposed to a high temperature, are suddenly subjected to a melting process and thereby form a coherent film, this also applies if the binders are arranged on a nonwoven, which is then embedded in the film as a strengthening reinforcement when the film melts together . This film formation under the temperature shock eliminates disturbances such as ("orange peel effect", "roller marks", "doctor strip", "raster effect", etc.), which are very often the result of even the most careful recipe design and viscosity control Due to the high melting temperature or the high MFT, the film formed in the melting process solidifies immediately after leaving the temperature zone, so that immediately after the temperature shock the stackability, blocking resistance, opening developability etc. and at the same time there is resistance to mechanical and chemical effects of the surface formed, it has proven to be particularly advantageous to use dispersions, for example based on acrylates, methacrylates, and their esters, nitriles, amides, vinyl acetate Styrene

REPLACEMENT LEAF Use butadiene, vinyl propionate, isobutene, polyurethane, vinylidene.

Hard resins which are water-soluble or made water-soluble by amination are preferred. Reactive resins which are water-dilutable or are dispersed / emulsified in water by means of suitable emulsifiers can be used in conjunction with the corresponding catalysts , Promoters, accelerators (possibly latent settings) as part of the thermal hardening to improve the resistance to mechanical and chemical action.

Hard resins are, for example, copolymers of styrene and acrylic acid, while reactive resins, e.g. systems capable of polycondensation (melamine-urea resins), resins capable of polymerization (polyesters, acrylate resins) or resins capable of polyaddition (polyurethane compounds) with the corresponding catalysts or reactants.

If latent hardener systems are used, the production of 1-component materials is possible. The prerequisite here is that the light-off temperature is above 100 ° C.

Water-thinnable liquids with reactive groups, which are included in the chemical reaction as binder constituents, can help to reduce the viscosity with a high solids content. You can also have a clearly positive influence on the curing and film properties. Examples of such reactive diluents are polyols, polyethers, polyetherols and epoxides, each with at least two reactive groups. As a recipe

REPLACEMENT LEAF Turbo blocks can be used to influence the processing and film properties of film formers (polyvinyl alcohol), plasticizers, wetting agents, defoamers, matting agents, etc.

The short temperature shock according to the invention - the short-term heating also has the advantage that only the coating which is actually to be melted into a film is heated, and not, for example, the carrier material, even if the layer has been applied directly to the carrier material can be achieved in various ways, for example also by radiant heat. However, it is preferably provided that the pre-dried layer is melted into a film in direct contact with a surface which serves as an energy source and is approximately 100 to 200 ° C., it being additionally advantageous if the film is immediately behind that for its formation leading heater is cooled. Corresponding to the preferred contact heating, either on a press surface, or preferably on a heated calender roll, any cooling of the film after the film-forming heating device should possibly also be carried out by a cooled calender roll. Instead or in addition, contact-free nozzle cooling can also be provided.

In the method according to the invention, the hot precipitation of a high concentration of wax or paraffin is of considerable importance, since in addition to an extremely fine distribution of the wax or paraffin, this results in a kind of coating effect of the individual dispersion particles by wax particles. This results in a significant improvement in the rheological properties and, as a result, very uniform application layers, regardless of the type of application of the layer. Come in addition

REPLACEMENT LEAF nor that during melt flow hardening, because of this coating of the dispersion particles by wax, there is a very rapid, uniform melting together, in which, obviously, chemical reactions which have not been researched in detail also occur, since the layers formed in this way, in addition to having a high mechanical hardness, are extremely hard are also resistant to liquids. It has been shown that even after days, liquids have not yet passed through such a layer.

In addition, the proportion of waxes or paraffins which are preferably hotly precipitated enables a very simple transfer process in such a way that the film is first formed on a roller or an endless belt and from there the actual carrier is also transferred. By means of this transfer process according to the invention, porous surfaces in particular, which are rough in their surface structure, can be provided with a smooth coating layer without having to use excessively large amounts of dispersing agent, since the agent does not have to be applied wet to the porous surface and therefore also not can penetrate to a high degree.

While hot precipitation of waxes has particularly good properties, but is not an indispensable prerequisite for a usable result, a relatively high proportion of wax in the order of magnitude of at least 3 to 10% or even more is of particular importance. In addition, it has proven expedient to combine wax and emulsifier during the wax precipitation.

The following waxes have proven to be particularly suitable for the purposes according to the invention: montan waxes (montanic acid or montan ester waxes), polyethylene waxes, polymer di

REPLACEMENT BLADE version, natural waxes, ethylene / vinyl acetate copolymers in combination with suitable emulsifiers.

Not only the type of wax or paraffin used, but also the selected emulsifier system have a decisive influence on essential processing and surface properties (flow, gloss, separation effect, hardness, resistance). By adding appropriate emulsifiers, e.g. the detachment from the plastic tape can be completely prevented, so that an excellent laminating adhesive can be obtained in this way.

The hardness, the viscosity and the gloss are also very strongly influenced by the respective emulsifier (on a combination of different emulsifiers), an emulsifier amount of approx. 2 to 6% based on the overall recipe having proven to be very expedient.

Finally, the following substances have proven particularly suitable as emulsifiers: oleic acid ethoxylate, fatty alcohol ethoxylate,

Oleic acid alkylnolamide or - preferably - castor oil ethoxylate.

The transfer process also allows the very simple production of structured films, in that the roller or the belt has a corresponding surface structuring which is then retained accordingly after the transfer to the actual carrier.

The transfer process should be carried out with particular advantage in such a way that the actual film formation, i.e. the film formed from a pre-dried dispersion layer is melted together with the transfer.

REPLACEMENT LEAF The above-mentioned possible surface structuring of the nonwoven or fabric-reinforced binder films has the great advantage that, for example, by setting a matt surface, the legibility of the prints or lettering compared to an excessively high-gloss surface and the disturbing reflections that occur in this way is greatly increased can improve.

In addition, it also largely depends on the binder combination used whether the nonwoven is first applied to the transfer belt or on a transfer roller and then the, in the transfer method preferred for the mass preservation of archival documents compared to the direct coating method which is of course also possible Soak the dispersion solution and the fleece or vice versa, whether you first apply a film to the dispersion and apply the fleece or fabric to it. In the former case, larger amounts of dispersion can be stored in the nonwoven or woven fabric, so that a greater impregnation is ensured and thus also the greatest possible transparency of the reinforced film.

It is of course within the scope of the invention, even when carrying out the transfer process, to actually carry out the pre-dried film with embedded fleece or fabric and to transfer and melt it onto the archival material to be preserved in a single operation, or else initially to melt a film of the binder and the nonwoven or fabric on the transfer belt and to take off this finished thin film and to wind it up on a roll in order to then deliver these prefabricated armored films to the libraries, for example, which then only have a relatively small, simple calender will need to to be able to melt such a film onto the archivals to be protected. The binder combination then melts a second time, but this is possible without any problems, since the binder composition can be reactivated, that is to say thermoplastic.

To carry out the method according to the invention, it is particularly advantageous to provide an endless transfer belt made of plastic or metal between a drying device and a transfer station with heatable transfer rollers or transfer belts and optionally an inlet and outlet for the substrate to be coated On the return path from the transfer station or the winding device for the prefabricated film, an application device and a feed station for the nonwoven or fabric pass.

It is true that the preferred transfer process can also be carried out with the aid of a transfer roller, to which the dispersion layer is first applied and pre-dried in order to be transferred from it to the actual carrier. In practice, however, a transfer belt is generally advantageous simply because of the greater length. The greater length of a transfer belt enables a problem-free arrangement of a large number of application stations and an independent predrying before the melt contact hardening, so that in practice a transfer device with the aid of a transfer roller can only be used advantageously in special cases.

Although the film according to the invention formed by melt flow hardening can be removed from the transfer belt or the transfer roller quite easily - any loose particles are automatically removed by the nozzle cooling -

REPLACEMENT LEAF In some cases it may nevertheless be useful to arrange a cleaning device for the transfer belt in front of the application device in order to remove any remaining coating parts or layers on the transfer belt in the event of any malfunctions, so that they do not interfere with the subsequently formed film become. The application devices for intermediate layers, for example an already mentioned adhesion promoter layer or a color primer layer or the like, are arranged downstream of the drying device, the use of a transfer belt instead of a transfer roller again having structural and procedural advantages.

In addition to the use of cooled cooling rollers or a nozzle cooling which immediately follow the heatable transfer rollers in order to ensure a particularly sudden cooling of the film formed by melt flow hardening and thus a completely unproblematic further processing of the coated carrier, the invention can also be further developed it should be provided that a detour of the transfer belt relative to the carrier to be coated is provided between successive transfer rollers. As a result of this detour, both shocks of the strip and small surface defects cannot decisively affect the quality of the finished film, since such defects are no longer arranged in the area of two successive rollers at the same location on the coating.

Corresponding silicone release papers can also be carried to improve the release effect and to achieve certain (eg very matt) surfaces. Further advantages, features and details result from the following description of some exemplary embodiments and from the drawing. Show:

1 and 2 different schematic exemplary embodiments of double belt machines according to the invention and

3 and 4 are schematic representations of calender machines for the mass preservation of archive materials according to the invention.

In the double belt machine shown in FIG. 1, the archive materials indicated as sheets 1 are fed via belt B to a double belt machine 2, the upper belt of the double belt machine 2 being designed as a transfer belt 3. The binder dispersion is applied as a layer to this transfer belt 3 made of steel or plastic in a station 4, while a thin fleece or paper 7 is applied from a roll 6 in a subsequent station 5. The fleece or fabric impregnated with the dispersion is moved past a drying station 8 with, for example, hot air nozzles, so that the binder is dried on. The transfer belt with the dried impregnated fleece then passes between the rollers of the double belt machine, at least the upper input roller 9 being heated in such a way that the sheet to be preserved is melted together with the sheet to be preserved and the binder is melted together to form a film . The counter-pressure roller 10 to the roller 9 should not be heated when sealing on one side, in order to avoid heating the sensitive archival documents, that is to say the sheet 1. In the same way, the rollers 11 and 12 should be cooled as much as possible in the outlet nip of the double belt machine in order to limit as far as possible the risk of the archives being heated from the heated film layer. If both sides are to be sealed at the same time in one pass, the counter-pressure roller must of course also be heated, since in this case sealing fleece is also supplied from the opposite side.

The arrangement according to FIG. 2 differs from that according to FIG. 1 only in that the arrangement of the binding agent application station 4 and the fleece feeding station 5 are interchanged, ie. H. that the fleece or fabric is first applied to the transfer belt 3 and then is directly impregnated with the binder dispersion.

Furthermore, it is indicated in FIG. 2 that the film tape melted together in the double-belt machine with internal fleece or fabric reinforcement can also be pulled off via a roll 13, in which case, of course, no sheets 1 are fed in at the input side. The roll 13 is then fed to the corresponding libraries, archives or the like, so that they can apply the prefabricated film to the archive material with the aid of a simple laminating machine. Even if sheets are fed in, it is advantageous to roll up and then seal the opposite side in the second pass. In most cases it is useful to roll up the sealed archival material in order to cut and trim it later.

FIGS. 3 and 4 show a deviation from the double-belt machines according to FIGS. 1 and 2 calender devices, but the mode of operation is essentially the same for the rest. The transfer belt 3 again runs past the binder application station 4 and the nonwoven feed station 5 (or vice versa in FIG. 4). About a heated deflection drum 14, and in addition a hot air nozzle dryer section 15 can be provided, the pre-dried layer reaches the heated calender 16 whose feed gap 18 the sheets 1 to be preserved are fed. Between the calender 16 and its counter-pressure roller 10, the nonwoven with the binder mixture and the sheet 1 are brought together, the binder mixture melting onto the sheet 1 as a film with an imaginary nonwoven or fabric. Following the calender, cooling is provided at 17, which can either be contact cooling by means of a roller or else an air nozzle cooling. In FIG. 4, as in FIG. 2, it is again indicated that the film formed on the calender from the nonwoven or woven fabric with the binder mixture by melting together does not have to be melted directly onto the sheet 1 when it is formed, but that it also has to be melted can pull off over a roller 13 in order to then make it available as a prefabricated film to smaller libraries which then only need a simple melting calender in order to be able to melt such a film onto their archival material for sealing purposes.

In addition to the arrangement shown, in which only one side is provided with a sealing layer, the formation can of course also be such that a film layer is applied to the top and bottom of the sheets 1 at the same time.

REPLACEMENT LEAF

Claims

1. Process for the mass preservation of archival materials by melting a binder combination reinforced by a nonwoven or fabric, characterized in that nonwoven or fabric with an aqueous, pollutant-free self-crosslinking and / or externally crosslinkable and / or externally crosslinkable and / or externally crosslinkable or pre-crosslinked dispersion free of volatile solvents of a thermoplastic

Binder with a high film formation temperature above 60 ° C., into which waxes or paraffins with a concentration of 3 to 10% by weight, based on the solids content of the dispersion, have been incorporated by hot precipitation, soaked and dried and in Connection to the substrate to be preserved under the influence of pressure and temperature by means of a brief temperature shock with a temperature which melts the film formation temperature to form a film sealing the substrate with embedded fleece or tissue.

2. The method according to claim 1, characterized in that the substrate is sealed on both sides with a film reinforced by fleece or fabric.

3. The method according to claim 1 or 2, characterized gekenn¬ characterized in that the nonwoven or woven fabric contains cellulose fibers and / or glass fibers and / or plastic fibers and / or carbon fibers.

4. The method according to any one of claims 1 to 3, gekenn¬ characterized by the use of dispersions based

HE - Acrylates, methacrylates and their esters, nitriles, amides,

- vinyl acetate,

- styrene,

- butadiene,

- vinyl propionate,

- isobutene,

- polyurethane,

- vinylidene.

5. The method according to claim 1, characterized by the use of reactive thinners based on

- polyols, - polyethers,

- polyetherols or

- Epoxides with at least two reactive groups each.

6. The method according to any one of claims 1 to 5, gekenn¬ characterized by the use of waxes based on -Montan waxes (montanic acid, montan ester waxes),

- polyethylene waxes, - natural waxes, in combination with suitable emulsifiers.

7. The method according to claim 6, characterized in that as emulsifiers

- oleic acid ethoxylate,

- fatty alcohol ethoxylate,

- Oleic acid alkylolamide or castor oil ethoxylate can be used.

REPLACEMENT LEAF

8. The method according to any one of claims 1 to 7, characterized in that the binder film has a pH greater than 7.

9. The method according to claim 8, characterized in that the dispersion solvent-free alkalis, which do not split off pollutants, are added.

10. The method according to claim 9, characterized in that the dispersion epoxidized oils or 4-tertiary butyl catechol are added.

11. The method according to any one of claims 1 to 10, characterized in that the pre-dried layer in direct contact with an approximately 100-200 ° C hot, serving as an energy source surface is melted together to form a film.

12. The method according to any one of claims 1 to 11, characterized in that the film is cooled immediately behind the heater leading to its formation.

13. The method according to any one of claims 1 to 12, characterized in that the pre-dried layer by

Application of the liquid dispersion to a transfer roller or an endless transfer belt - before or after the feeding of the fleece or the fabric - is formed and is transferred from there to the actual carrier, with the transfer causing the melting to form a film .

14. The device according to one of claims 1 to 13, characterized by a ge between a drying device device and a transfer station with heatable transfer rollers and, if necessary, an inlet and outlet for the continuous transfer belt, which is made of plastic or metal and runs around the substrate to be coated, and which on the return path from the transfer station passes through an application device and a feed station for the nonwoven or woven fabric .

15. The apparatus according to claim 14, characterized in that a cleaning device for the transfer belt is arranged in front of the application device.

16. Device according to one of claims 14 and 15, da¬ characterized in that cooled cooling rollers are arranged behind the heatable transfer rollers.

17. The device according to one of claims 14 to 16, da¬ characterized in that the transfer rollers are designed as multiple calenders.

18. Device according to one of claims 14 to 17, characterized by a lifting device for controlling the contact time at different transfer belt speeds due to different looping of the calender roll.