WO2002042557A1

WO2002042557A1 - Solidifying agent and/or stabilizer

Info

Publication number: WO2002042557A1
Application number: PCT/EP2001/013567
Authority: WO
Inventors: Manfred Anders; Karl Bredereck
Original assignee: ZFB Zentrum für Bucherhaltung GmbH
Priority date: 2000-11-21
Filing date: 2001-11-21
Publication date: 2002-05-30
Also published as: DE10057554A1; DE10057554B4; EP1341966A1

Abstract

The invention relates to a solidifying agent and/or stabilizer for organic material, comprising a silylated derivative, dissolved in an unpolar solvent, of a compound that contains hydroxyl, carboxyl or amino groups. The invention further relates to a method for solidifying and/or stabilizing organic material, wherein said solidifying agent is used. The solidifying agent is inter alia used to preserve and restore paper, wood, textiles, paints and inks.

Description

FASTENING AND / OR STABILIZING AGENTS

The present invention relates to strengthening agents and / or stabilizing agents for organic material, a method for strengthening / stabilizing organic material and the use of the strengthening or stabilizing agents.

All products made of organic materials made of paper, wood, textiles or the like are subject to a more or less severe aging or decomposition. Here, for. B. paper mainly destroyed by acids, but also by oxidation processes or by the influence of microorganisms. Despite considerable progress in recent years, however, major problems, such as paper strengthening from non-aqueous media, in the preservation and restoration of books and documents are essentially unsolved.

The consolidation or stabilization of old, brittle organic materials, especially paper, is one of the central problems in the conservation and restoration of these materials. While new possibilities for the deacidification of paper, including the mass deacidification process, have been successfully developed, there are no satisfactory processes in the area of consolidation that allow paper consolidation, in particular entire book blocks, and, if possible, also serve to deacidify the paper.

It is known that severely damaged papers can be reattached using the paper splitting process. In this process, the paper is split and glued again together with a thin intermediate layer and a special adhesive that contains cellulose ether and a deacidifying agent. However, this very effective consolidation method involves a very high level of manual work and is therefore cost-intensive. Although it is possible to cut costs by machine paper splitting, this method also requires considerable effort, since a book is in the individual pages must be dismantled before the individual papers can be split, since only splitting individual pages is possible.

It is also known to solidify brittle paper by soaking the paper with acrylic acid derivatives and polymerizing it by irradiation with gamma rays. By adding amine-substituted acrylic methacrylate, the paper can also be deacidified to a limited extent. Disadvantages of this process, however, are the further damage to the already fragile paper due to the gamma radiation, the bleeding of colors and inks due to the impregnation with acrylic acid derivatives and the unpleasant smell of the residual monomers or oligomers remaining in the paper, which are also harmful to health.

Paper is also stabilized by lamination, with a thin polymer film being applied to the paper on one or both sides by melting or gluing. The disadvantage of this single sheet process is the increasing paper thickness, so that after treatment and consolidation the cover intended for the book no longer fits. As a further side effect, the handle and the appearance of the paper are changed significantly and the durability of the polymers used is not guaranteed. In addition, no simultaneous deacidification or mass treatment is possible.

In the parylene process, paper strengthening is carried out from the gas phase without a solvent. This process, developed by Union Carbide Corporation, is used primarily in the electronics industry. In this known process, the stable parylene dimer is first evaporated under vacuum at 150 ° C. and then split into the reactive monomers at 650 to 690 ° C. The reactive gas is then passed onto or over the object to be treated, on and in which it then polymerizes. The polymer penetrates into the paper into the pores and forms a stabilizing network around the paper fibers. Due to the high degree of crosslinking of the polymer, it is not soluble in any solvent. The treatment is therefore irreversible, ie the polymer can no longer be removed become. In addition, simultaneous deacidification is not possible with this process.

The Batteile Institute has also increased the strength of paper by up to 100% using hexamethyl diisocyanate as a strengthening agent. However, isocyanates are not compatible with any known soluble deacidifying agent and, when applied directly to the paper, form crosslinked polyureas, a further disadvantage being the increase in hardness of the paper.

The classic conservative method for stabilizing aged paper is re-gluing. Solutions of various water-soluble polymers, in particular cellulose or starch ethers, gelatin, but also polyvinyl alcohols or polyacrylates, are applied to the paper. Methyl cellulose has proven itself best for aqueous treatment, while hydroxypropyl cellulose is used as the solvent for treatment with alcohol.

Like methyl cellulose, almost all other polymers used in glue restoration are only soluble in water, with the exception of alcohol-soluble, highly substituted hydroxypropyl cellulose, ethyl cellulose and methyl cellulose. A problem which arises with the re-sizing is therefore the fact that sensitive papers which contain water- or alcohol-soluble inks or colors cannot be re-sized.

The object of the invention is therefore to provide a setting agent and / or stabilizing agent, a method for setting and / or stabilizing organic material in bulk and the use of this setting agent for the preservation and restoration of organic material, in which the further decomposition of the organic material prevented and the renewed stabilization by deacidification and consolidation can take place in one step and the stabilization of damaged objects to usable material is achieved. According to the invention, this object is achieved by claims 1, 7, 8 and 10. Preferred further developments result from the subclaims.

According to the invention, there is provided a strengthening agent for organic material which contains a silylated derivative of a compound containing hydroxyl and / or carboxyl and / or amino groups in a non-polar solvent. With this use according to the invention it is possible to make the previously only water-soluble resizing agents soluble in non-polar solvents by means of a temporary (intermediate) chemical modification. Due to the temporary masking of the polar hydroxyl, carboxyl and amino groups with non-polar substituents, which can easily be split off again, the polarity of the compounds used according to the invention can be reduced and compatibility with the deacidifying agent can also be achieved.

The agent according to the invention acts as a protective colloid against hydrolysis-sensitive deacidifying agents and thus delays the reaction of this deacidifying agent with water. This promotes the even distribution of the deacidifying agent with paper, whereby the pre-drying of the paper before deacidification no longer needs to be as extreme.

The degree of silylation of the various polyhydroxy compounds allows the solubility to be controlled in a targeted manner, and in principle solvents of the most varied polarity can be used universally. The higher the degree of silylation, the more non-polar the solvent must be. Thus, the modified polyhydroxy compounds used according to the invention can generally be adapted to almost all solvents, up to supercritical carbon dioxide as the solvent.

The combinations of silylated cellulose ethers with METE show an amazing further effect. The strong interaction between the polyvalent cations of the deacidifying agent and the post-sizing agent also has a positive effect on the distribution of the deacidifying agent on the paper. The silylated compounds act like a protective colloid on the METE because the treatment solution can be easily applied to the non-pre-dried paper without immediate hydrolysis. The hydrophobic silylated cellulose agents wrap around the deacidifying agent, protecting it from moisture and delaying hydrolysis. In addition, the silylated polyhydroxy compounds, in particular the silylated cellulose ethers, form a transparent film with the METE, which also prevents the formation of coarse crystallites from the deacidifying agent.

While the paper, which has not been pre-dried and only deacidified with METE, is completely coated with fine crystallites of the hydrolyzed deacidifying agent, no crystalline deposits of the deacidifying agent can be seen in paper treated with a combination of silylated polyhydroxy compounds and METE.

Because of this, a reduction in the pre-drying is also possible in the case of mass deacidification with the addition of such agents, which not only saves time but also has a positive effect on the paper, since less extreme drying also leads to less cornification.

For the single sheet treatment carried out without predrying, completely new possibilities also open up, since it is now also possible, e.g. B. with METE from non-polar solvents to deacidify materials directly.

Organosilyl compounds have been found to be suitable for the invention, the masking of the hydroxyl groups as a rule to trialkylsilyl ethers, usually trimethylsilyl ether, being a suitable method. Trimethylchlorosilane or hexamethyldisilazane can be used as the silylating agent, trialkylsilyl groups being preferred.

For the purposes of the invention, compounds containing hydroxyl, carboxyl or amino groups have been polysaccharides, carbohydrates and their derivatives, such as alkyl glycosides (e.g. butyl glucoside, octyl glucoside) and alkyl polyglycosides, cellulose and cellulose derivatives (e.g. cellulose ether), Starch and starch derivatives (e.g. starch ether), hemicellulose and hemicellulose derivatives, galactomannans and galactomannan derivatives, guar and guar derivatives, chitin and chitin derivatives, chitosan and chitosan derivatives, dextrans and dextran derivatives, dextrins and dextrin derivatives, xanthans and xanthene derivatives, polyvinyl alcohol derivate and polyvinyl , Gelatin and gelatin derivatives or polyethylene amines and their derivatives are shown to be promising. The conversion z. B. the cellulose or the cellulose derivative in the corresponding silylated cellulose derivative makes the resulting compound soluble in non-polar solvents.

In particular, organic solvents such as alkanes, alkenes or hexamethyldisiloxane (HMDO), supercritical carbon dioxide or halogenated hydrocarbons have proven to be suitable as non-polar solvents, the persilylated or almost persilylated compounds containing hydroxyl or amino groups, e.g. B. polysaccharides or the like, solve well and these are compatible as a solution with the deacidifying agents used in mass deacidification.

By blocking the hydroxyl groups, the silylated compounds are moreover compatible with the hydrolysis-sensitive deacidifying agents, such as magnesium alcoholates, titanium / magnesium alcoholates or the like, which are used in the various mass deacidification processes.

This derivatization opens up a wide spectrum for paper treatment from non-polar solvents. With the aid of the strengthening agent according to the invention, all common resizing agents already used in paper restoration can be modified and made soluble in non-polar solvents according to the following formula:

Masking Cell-OH> Cell-O-Si (Me) ₃ The conventional post-sizing agents, which have hitherto been used successfully in aqueous post-sizing, can be used as strengthening agents after an intermediate derivatization into a corresponding organosilyl derivative. This enables existing experiences about the compatibility of these substances with the paper and their aging behavior to be adopted. These substances also meet the high restoration requirements.

This method can also be used to integrate new additives into the chemical system of mass deacidification which, because of their polar nature, could not previously be used. These groups can also be masked here by means of an intermediate silylation of the polar hydroxyl, amine or carboxyl functions. In this way, silylated antioxidants, complexing agents (metal ion deactivators), radical scavengers, light stabilizers (UV stabilizers), peroxide decomposers, antiozonants or pesticides, in particular fungicides, bactericides or insecticides, can be incorporated into the chemical system of mass deacidification.

If these substances come into contact with moisture or water, even from the air, after treatment, the silyl group introduced by the chemical modification is slowly split off again and escapes as a volatile substance. Are z. B. trimethylsilyl ether of the corresponding hydroxyl compound, ultimately forms as volatile leaving substance hexamethyldisiloxane (HMDO), which can be used as a solvent in the deacidification process.

Cell-O-Si (Me) ₃ + H ₂ 0> Cell-OH + HO-Si (Me) ₃

2 (Me) ₃ Si-OH> (Me) ₃ Si-0-Si (Me) ₃ + H ₂ O

HMDO. The hydrolysis of the unstable (cellulose) silyl ethers is catalyzed by acids, but also by bases. Persilylated polysaccharide derivatives are relatively stable due to their hydrophobic character and hydrolyze only very slowly. The voluminous trimethylsilyl groups make it difficult for water to reach the ether oxygen atom (steric hindrance). In contrast, celluloses with an average degree of substitution (MS) of 1, 5 or less hydrolyze very quickly because they do not have this steric hindrance. No catalysis is necessary here, as these compounds already hydrolyze through the air humidity within a few hours. One only observes a very slow hydrolysis on persilylated celluloses, which accelerates with increasing degree of hydrolysis.

The degree of substitution (degree of silylation) makes it possible, on the one hand, to vary the solubility of (polyhydroxy) compounds, in particular polysaccharides, from polar (water) to nonpolar (petroleum ether) and, on the other hand, to specifically control the sensitivity to hydrolysis.

In the deacidification and consolidation by means of the consolidation agent according to the invention for consolidation by post-gluing with silylated cellulose ethers from non-polar solvents, only the substances which are now unmodified remain on the paper together with the deacidification substance after the hydrolysis by the atmospheric moisture. This also applies to all other silylated additives.

For the strengthening of paper in mass deacidification, particularly persilylated, low molecular weight methyl celluloses in concentrations of 0.01 to 5% by weight, in particular 0.5% by weight, in the treatment solution have proven to be suitable. In the case of brittle, horny papers, the addition of 0.001 to 0.5% by weight, preferably 0.1% by weight, of persylated butyl glucoside can have a positive effect on flexibility. Depending on the aim of the treatment, the resistance of the paper to oxidative degradation processes can be improved by adding antioxidants.

In this way - via a temporary chemical modification - the substances known from aqueous treatment can also be used from non-polar solvents, whereby the compatibility with hydrolysis-sensitive deacidifying agents enables simultaneous deacidification of the organic material to be treated.

With the agent according to the invention, paper is preserved and restored; Wood, textiles, paints and inks, as well as a fixation of soluble inks before an aqueous treatment possible.

The invention is explained in more detail below with reference to the examples:

In Examples 1 and 2 below, the paper sheets were coated directly on both sides with the setting agent and deacidifying agent without predrying. The additive additive in the strengthening agent solution is 2% by weight in all tests, if no additional information is given. Naturally, aged, acid-glued wood pulp paper from 1961 was used as the paper.

The results of the paper strengths were determined by elongation at break test in the running direction of the papers as work load [J / m ² ]. The mechanical strength of the samples was tested both immediately after the treatment and after five weeks (35 days) of artificial aging at 80 ° C., 65% relative atmospheric humidity.

In the following, the abbreviation "-Si" stands for the silylated derivatives of the corresponding compound. Example 1 Deacidification and consolidation with magnesium monobutyl triglycol ether carbonate (Lithco;

FMC) as a deacidifying agent

It is known from the literature that the monobutyl triglycol ether as magnesium alcoholate (MG3) in the deacidifying agent from Lithco (FMC) is said to have a fixing effect on the paper. However, the results of a comparative study showed that MG3 did not have any additional stabilizing effect on naturally aged wood sanding paper (federal budget plan 1961), on the contrary, there was a slight (slight) decrease in strength directly after the treatment.

The corresponding tests are given in the table below, 0.05 mol of MG3 per liter of petroleum ether being used as the FMC deacidifying solution. HPC = hydroxypropyl cellulose (MS ~ 5)

Table 1

Artificial additive Aging: 0 days artificial Aging: 35 days

[J / m ² ] [J / m ² ] untreated sample 7026 3150 only deacidified (0.05 m MG3) 5609 6270 ent. + HPC - Si 6128 7392 ent. + Cellulose - Si 6133 8039 ent. + Cellulose - Si (4%) 7117 8313

The silylated cellulose derivatives compensate for part of the loss of strength due to deacidification. In the course of artificial aging, the silyl groups on the cellulose ethers split off, the molecules becoming more polar and thus also being able to form stronger interactions with the paper fibers. As a result, the strength of the paper increases. Papers treated with strengthening agents and deacidifying agents have a higher strength after the artificial aging than the untreated paper before the artificial aging. Example 2

Deacidification and consolidation with magnesium titanium ethanolate (METE) in HMDO as

Deacidifying agent in single sheet treatment (without predrying):

In these experiments, a 0.05 molar solution of METE in HMDO was used as the deacidifying solution. This deacidifying agent has proven itself in mass deacidification for several years.

Table 2

Artificial additive Aging: 0 days artificial Aging: 35 days

[J / m ² ] [J / m ² ) untreated sample 7026 3150 only deacidified (0.05 m METE) 7545 4612 ent. + Methylcellulose-Si (0.2%) 8343 6532 ent. + HPC - Si 8540 8903 ent. + Methylcellulose-Si (1%) + 10057 8604

Butyl triglycol ether (1%)

As Table 2 above shows, the use of silylated cellulose ethers leads to a significant improvement in strength.

The effect of these additives as a protective colloid for the deacidifying agent is already apparent when the solutions are applied to the papers. Without an additive, this type of application results in immediate hydrolysis of the deacidifying agent on the paper surface, the papers then being covered by a white, dusty layer of finely crystalline hydrolyzed deacidifying agent.

The strengthening agent used according to the invention, in the present case a silylated cellulose ether, significantly delays the hydrolysis of the deacidifying agent. The hydrophobic silylated cellulose ethers encase the deacidifying agent. This protects it against moisture and hydrolysis delayed. The treatment solution can easily be applied to the (not pre-dried) paper without immediate hydrolysis. The silylated cellulose ethers form a transparent film with the METE. This is also shown by the following scanning electron microscopic images. While the paper that has only been deacidified with METE is completely coated with fine crystallites of the hydrolyzed deacidifying agent (Fig. 1), no crystalline deposits of the deacidifying agent can be seen in the paper that has been treated with a combination of silylated cellulose ether and METE (Fig. 1) .2). The formation of a film and the use of a deacidifying agent do not result in dusty deposits of the hydrolyzed deacidifying agent on the paper.

In this way (see Examples 1 and 2), the very hydrolysis-sensitive deacidifying agents of the mass deacidification processes can be used directly in single sheet treatment, even without pre-drying the paper.

Example 3 Deacidification and consolidation with METE in HMDO as deacidifying agent in the

mass treatment

For the treatment of entire book blocks, the common mass deacidification method of the Deutsche Bücherei (Leipzig) was adopted in almost all work steps. Various silylated additives were added to the treatment solution (METE in HMDO). The results are summarized in Table 3.

Table 3

Artificial additive Aging: 0 days artificial Aging: 35 days

[J / m ² ] [J / m ² ] untreated sample 7026 3150 only deacidified (METE) 7698 6899 ent. + Methylcellulose-Si (0.2%) 8799 7989 ent. + HPC - Si (1%) 8325 7566 ent. + Methyl cellulose Si (1%) + 10927 9001 butyl triglycol ether (1%)

As can be seen from the table above, the strengthening agent for organic material according to the invention leads to a significant and permanent improvement in the mechanical strength of the paper.

Due to the protective colloidal effect of the silylated polyhydroxy compounds on the hydrolysis-sensitive deacidifying agent, the hydrolysis of the deacidifying agent can be retarded to such an extent that such extreme predrying, as is common today, is no longer necessary in mass deacidification.

Example 4 Fixing wooden objects

Old and partly moldy wooden objects, in which the cellulose part has already largely decomposed, are treated with a persylated trimethylsilyl cellulose (TMSC) dissolved in pentane. After filling the voids in the wooden article with this solution, e.g. through a vacuum impregnation, the volatile pentane evaporates.

TMSC hydrolyzes to pure cellulose at room temperature in about 6 months. The cellulose formed in this way is again in the interior of the wood, which is therefore as fiber-forming semi-crystalline substance again contributes to a considerable stabilization of the wood.

Example 5 Fixation of solvent-sensitive paints and inks before an aqueous one

treatment

Paints and inks that bleed easily in water, for example stamping inks, can be fixed with highly substituted polysaccharide silyl ethers before aqueous treatment. The effectiveness is best if the paper to be treated is coated on both sides with a solution of highly substituted polysaccharide silyl ethers. At these points, the paper becomes so hydrophobic that no polar solvent (water) reaches the colors and inks and bleeding does not occur. Here too, a deacidifying agent that is also dissolved in the treatment solution, e.g. METE the paper to be deacidified at these areas.

Depending on the molecular weight / viscosity of the silylated cellulose ether, a 0.5 to 5% by weight solution with heptane or pentane is preferably used as the solvent.

Claims

1. Fixing and / or stabilizing agent for organic material, containing at least one silylated derivative of hydroxyl and / or carboxy and / or amino group-containing compounds in a non-polar solvent.

2. Fixing and / or stabilizing agent according to claim 1, characterized in that the silyl groups are organosilyl compounds.

3. strengthening and / or stabilizing agent according to claim 1 or 2, characterized in that ß the compounds containing hydroxyl, carboxyl or amino groups polysaccharides, carbohydrates and their derivatives, cellulose and cellulose derivatives, starch and starch derivatives, hemicellulose and hemicellulose derivatives, Galactomannans and galactomannan derivatives, guar and guar derivatives, chitin and chitin derivatives, chitosan and chitosan derivatives, dextrans and dextran derivatives, dextrins and dextrin derivatives, xanthans and xanthene derivatives, polyvinyl alcohol and polyvinyl alcohol derivatives, partially hydrolyzed polyvinyl acetate and their derivatives or gelatin and gelatin can be.

4. Fixing and / or stabilizing agent according to one of claims 1 to 3, characterized in that the non-polar solvent is an organic solvent.

5. Fixing agent according to one of claims 1 to 4, characterized in that the fixing agent contains additives.

6. A method for strengthening organic material, characterized in that the organic material to be treated is introduced into a solution of the strengthening agent according to one of claims 1 to 5.

7. A method for stabilizing organic material, characterized in that the organic material to be treated is introduced into a solution which, in addition to the deacidifying agent, contains further additives for stabilizing against chemical or biological aging processes.

8. Use of a strengthening agent according to one of claims 1 to 5 for the preservation and restoration of papers, wood, textiles, paints and inks, and for fixing soluble inks before an aqueous treatment.