JPH0857812A - Method for treating water exposure organic remains for storage - Google Patents

Abstract

PURPOSE: To control an impregnation concentration by a temperature, reduce a treating period of time by a simple device, and obtain brittle water immersion organic remains having a microbial resistance, a shelf stability even under a high-temperature and -humidity environment, and a sufficient strength while keeping a dimensional stability. CONSTITUTION: Water immersion organic remains are dipped in a saturated water solution of sugar-alcohol. The water immersion organic remains are impregnated with the sugar-alcohol by successively raising the temperature of the saturated water solution from a room temperature to 60-80 deg.C. After that, the water immersion organic remains are taken out of the saturated water solution and dried. The saturated water solution of sugar-alcohol depends on the temperature increase thereof, but it is preferable that the sugar-alcohol is initially excessively loaded for always keeping the saturated state of the sugar-alcohol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preserving water-immersed organic remains excavated from ruins.

[0002]

2. Description of the Related Art Water-immersed organic relics, especially wood, found in archaeological sites are weakened by the decomposition of cell tissues by microorganisms before being buried in soil. This is a result of the fact that the polysaccharides constituting cellulose and hemicellulose, which are the main components of wood, are decomposed by microorganisms and significantly reduced. The brittle and weakened excavated water remnants of organic matter contain excess water, and if dried as it is, it contracts significantly and loses its value as a cultural property.

Therefore, as a storage method for drying a fragile water-immersed organic matter while strengthening it, a water-soluble polymer material such as polyethylene glycol (PEG # 400) has hitherto been used.
0), a method of impregnating an aqueous solution of sucrose with a water-immersed organic relic to strengthen it, or a method of substituting water in wood with an organic solvent and then impregnating it with a higher alcohol or polyethylene glycol. is there.

[0004]

In the conventional method of impregnating a polymer material such as polyethylene glycol, the heating device must be operated for a long period of time, and the decomposition of the polymer deteriorates the water-immersed organic relics. However, there are drawbacks such as corrosion of the heating device and insufficient penetration of the inside of the water-immersed organic relics. Further, the method using an organic solvent has drawbacks such as fire and safety.

The conventional method of impregnating sucrose is that fragile water-immersed organic relics cannot be sufficiently strengthened, decomposes during heat treatment to cause browning, sucrose dissolves in a high humidity environment, and There are drawbacks such as the possibility of decomposition.

[0006] In any of the above-mentioned conventional methods, a long-term processing period of a year is required for preservation processing, large-scale equipment is required, cost is high, and it is difficult to cope with recent excavation amounts. There are drawbacks.

The present invention improves the above-mentioned drawbacks of the prior art, controls the impregnation concentration by temperature, shortens the treatment period with a simpler device than before, is less susceptible to microorganisms, and is stable in hot and humid environments. It is an object of the present invention to provide a method for preserving water-immersed organic relics, which can be preserved by storing the fragile water-soluble organic relics and can be reinforced sufficiently while maintaining dimensional stability.

[0008]

Means for Solving the Problems The water-immersed organic relic is immersed in a saturated aqueous solution of sugar alcohol, and the temperature of the saturated aqueous solution is gradually increased from room temperature to 60 to 80 ° C. to impregnate the water-immersed organic relic with the sugar alcohol. After that, the water-immersed organic relic is taken out from the saturated aqueous solution and naturally dried or freeze-dried. It is preferable to initially add the sugar alcohol in excess so that the saturated aqueous solution of the sugar alcohol always maintains the saturated state of the sugar alcohol even if the temperature rises.

[0009]

[Function] By increasing the temperature of the saturated aqueous solution, the concentration of the sugar alcohol is increased, and the penetration of the sugar alcohol into the water-immersed organic remains is promoted. By drying the water-immersed organic remnant impregnated with sugar alcohol, water is removed and sugar alcohol crystallizes.
The sugar alcohol crystallized by impregnating the water-immersed organic relics stabilizes the dimensions of the water-immersed organic remnants, prevents decay from microorganisms, and has a low hygroscopicity, and thus stabilizes the water-immersed organic relics.

[0010]

EXAMPLES Generally, it is necessary for a preservative for water-immersed organic remnants to satisfy the following conditions. High solubility in water Capable of strengthening the structure of fragile organic relics (Crystallinity) Small molecular weight so that it can penetrate into the structure of organic relics High heat stability Non-decomposing to organisms Moisture absorption It has low properties and is stable under high humidity conditions.

Table 1 shows a comparison of the above-mentioned conditions of the conventional preservative and sugar alcohol.

[0012]

[Table 1]

In order to strengthen fragile wood products, it is necessary to impregnate the interior of wood with a highly concentrated aqueous solution. Therefore, Table 2 shows the solubility of saccharides and PEG in water. PEG is mixed with water at an arbitrary ratio, but with natural sugar, sucrose dissolves up to 76% when heated to 70 ° C. On the other hand, the sugar alcohols xylitol (Xylitol) dissolves up to 87%, lactulose (Lactulose) up to 85%, and maltitol up to (Maltitol) up to 80%.

[0014]

[Table 2]

The stability of wood products after storage treatment under high humidity conditions is an important issue in hot and humid regions such as Japan. Considering moisture absorption and dissolution of PEG in a high humidity environment, which has often been a problem in the past,
It is necessary to select a material that is less hygroscopic than PEG. As shown in Table 3, when the critical specific humidity was estimated from the moisture absorption of saccharides and PEG estimated from the increase in water content at constant humidity, PEG # 4000 was around 80%, sucrose was around 80%, and sugar alcohol was around. Xylitol is about 60
%, Maltitol has an extremely low hygroscopicity of about 85% and lactulose of about 90%.

[0016]

[Table 3]

As described above, PEG (# 200, # 40
00) or sucrose and sugar alcohols such as xylitol, lactulose, and maltitol, PEG # 4000, which is a conventional storage material, has problems in permeability, heat stability, color change, and hygroscopicity, and PEG # 200 Although it has high penetrability, it has problems with PEG # 4000 or higher in color change and hygroscopicity. In addition, sucrose is advantageous over PEG in many respects, but has problems of non-decayability and hygroscopicity. On the other hand, various sugar alcohols are compared with polyethylene glycol ((PEG # 4000) and sucrose which have been conventionally used,
It was found to be extremely effective as a preservative material for excavated organic relics, such as its solubility in water, thermal stability during impregnation, and stability under high humidity conditions during storage. It is also important that sugar alcohol has the property of being less susceptible to being invaded by organisms than sucrose. From such comparison, sugar alcohol is effective as a material for preserving excavated organic relics. In particular, lactitol and maltitol are excellent under the above conditions, and are considered to be ideal materials for preserving water-immersed organic remains. Lactitol and maltitol are new materials that have never been used as preservatives for waterlogged organic relics.

Therefore, the water-immersed organic relic is immersed in a saturated aqueous solution of sugar alcohol, preferably lactitol or maltitol.

The liquid temperature is gradually increased to 60 to 80 ° C.,
The temperature of the saturated aqueous solution is raised by raising the liquid temperature.

The saturated aqueous solution of sugar alcohol is preferably charged with an excess amount of sugar alcohol so that the concentration thereof increases as the liquid temperature rises.

The immersion period of the water-immersed organic remains depends on the size of the water-immersed organic remains, but is immersed for 3 days to 3 months.

The water-immersed organic remains impregnated with sugar alcohol are taken out from the saturated aqueous solution and dried. The method of drying is to leave it indoors to dry naturally. When the impregnation concentration of sugar alcohol is low, it is preferable to freeze-dry.

[0023]

[Experimental results] The effects of preservative treatment were measured using a sample of broad-leaved trees from the decayed Jomon period (3000 years ago), which is the most difficult to preserve among the waterlogged organic relics. The experimental results are shown in Table 4.

[0024]

[Table 4]

Using zelkova as an example of degraded hardwood,
Table 5 shows the results of an experiment on the change in dimensional stability depending on the shrinkage rate of the cusp surface (βcs cusp area), and the contraction state is shown in Photo 1. Degraded zelkova (saturated water content = 619%, shrinkage ratio βrad (radial direction) = 25.00, βtan (tangential direction) = 69.30, βcs (tree mouth area) = 76.9
In the experiment using 8), the sucrose-impregnated material showed almost no dimensional stabilizing effect at the stage of impregnation with 9%, but thereafter, the shrinkage rate of the wood surface tends to decrease almost linearly. 8
Shrinkage rate when impregnated with 0.8% is βrad = 0.65, βta
Since n = 2.98 and βcs = 3.62, the shrinkage rate at the time of 89% impregnation in which the concentration was increased in the supersaturated state further increased, and the shrinkage rate on the cusp surface became 0.91%. PEG # 4000
Shows the best result among the three kinds of chemicals at the 9% impregnation stage, but the worst result at the concentration increasing stage from 23.1% to 54.5%. However, at higher concentrations, the dimensional stability improved again,
%, 80.8% and 92% show good results along with lactulose. Lactulose improves dimensional stability while drawing a gentle curve as the impregnation concentration increases.
This curve is almost parallel to sucrose, but the dimensional stability of lactulose is always superior to that of sucrose. The shrinkage ratio at the impregnation concentration of 89% is βrad = 0.29, βtan =
Since −0.75 and βcs = −1.04, βrad has almost no contraction, and βtan tends to slightly expand.

[0026]

[Table 5]

[0027]

[Photo 1]

Next, as an example of deteriorated coniferous trees, Table 6 shows the results of an experiment in which the dimensional stability was changed by the shrinkage ratio (βcs) of the xylem surface using cypress. Cypress (saturated water content =
389%, shrinkage ratio βrad = 3.47, βtan = 1
In the experiment using 0.88, βcs = 13.97), P
The three impregnation methods of EG # 4000, sucrose and lactulose both showed good dimensional stability. Of these, the lactulose impregnation method always exhibits the best dimensional stability. From the stage of 9% impregnation, the shrinkage rate of the wood surface gradually decreased to 80.8%.
The contraction rate at the impregnation concentration of βrad = 0.00, βt
A sufficient dimensional stability effect of an = 0.73, βcs = 0.73 was obtained. On the other hand, the shrinkage ratio of PEG # 4000 is 5
At the impregnation concentration of 4.5%, the cusp contraction rate is 7.51%, which is slightly inferior, but at the impregnation concentration of 80.8%, the cusp contraction rate is a good value of 1.86%. Sucrose improves the dimensional stability while being almost parallel to lactulose, and exhibits a good shrinkage ratio of 0.84% at the mouth end surface at an impregnation concentration of 80.8%.

[0029]

[Table 6]

As described above, lactulose is always higher in dimensional stability than sucrose, and there is no unstable situation at a specific concentration such as PEG # 4000. Lactulose has a dimensional stability effect of 2% in terms of shrinkage at the mouth of the mouth if the impregnation concentration is about 80-90% for degraded hardwood (saturated water content = 619%) and softwood (saturated water content = 389%). Can be given.

Table 7 shows the shrinkage condition of the wood surface of the experiment using cypress (saturated water content 389%). Cypress (saturated water content = 389%, shrinkage βrad = 3.47
%, Βtan = 10.88%, βcs = 13.97), lactulose has the highest dimensional stability and 54.5%.
The shrinkage rate (βcs) of the mouth end surface has already reached 1.9% at the concentration of. Sucrose impregnation method at the same concentration 3.3%, PEG # 4
It is 7.5% in the 000 impregnation method, which shows that the dimensional stability is high with respect to degraded softwood.

[0032]

[Table 7]

Table 8 shows the shrinkage of the wood surface of the experiment using zelkova (saturated water content 619%). Zelkova (saturated water content = 619%, shrinkage ratio βrad = 25.00, βtan
= 69.30, βcs = 76.98), good dimensional stability cannot be obtained in any impregnation method unless impregnated with a high-concentration solution of 80 to 90%. The dimensional stability effect was good in the order of lactulose ≧ PEG # 4000> sucrose impregnation method, but slight expansion was observed in the tangential direction with lactulose, and deformation was observed with PEG # 4000.

[0034]

[Table 8]

As described above, the lactulose impregnation method is effective for dimensional stabilization of various water-leached soil woods having different tree species and water contents, and its anti-shrinkage effect (ASE) is always higher than that of sucrose, and PEG It was found that even when compared with # 4000, high dimensional stability was exhibited depending on the tree species and deterioration state.

Table 9 shows the experimental results on the deformation of wood (zelkova) when immersed in a 50% high-concentration solution, and Photo 2 shows the shrinkage. First, PEG # with high molecular weight
The sample immersed in 4000 was extremely deformed. In other samples dipped in the solution having a low molecular weight, those dipped at room temperature hardly deformed, and slightly deformed in the heating state at 70 ° C. This modification was in a state in which lactulose was more stable than sucrose, and PEG # 200 showed a slight swelling tendency. Also, looking at the weight change rate of the wood due to the temperature difference of the impregnation solution, PEG # 4000 significantly decreased due to the volume change due to deformation, and the effect of heating by impregnation was the order of lactulose>sucrose> PEG # 200. Was recognized.

[0037]

[Table 9]

[0038]

[Photo 2]

As a result of the preservation treatment experiment, the sugar alcohols of new materials, lactitol and maltitol, showed high dimensional stability as compared with the conventionally used polymer materials (PEG # 4000) and sucrose. Comparing the anti-shrinkage effect (ASE), which is an index showing the shrinkage prevention effect, a conventional method of impregnating polyethylene glycol (βtan92.
9, βrad95.0) or a method of impregnating sucrose (βt
An 86.3, βrad 85.7), and a method of impregnating lactitol (βtan 93.2, βrad9)
9.5) and the method of impregnating maltitol (βtan
90.2, βrad96.8) showed good results. More importantly, the impregnation period can be greatly shortened as compared with the conventional method. This is because in the case of sugar alcohol, the shrinkage of the wood due to the increase in the concentration is hardly seen, so that the concentration can be rapidly increased.
Inferring from the results of the experiment, the storage processing period can be shortened to one fifth of the conventional one, so that a dramatic reduction in the processing period can be expected.

[0040]

[Effect] The method for preserving water-immersed organic relics according to the present invention has the following effects. 1. It is possible to prevent microbial damage during impregnation due to non-decaying material. Therefore, it is suitable for preservation of flooded organic relics in hot and humid areas. 2. The sucrose impregnated material is damaged by ants, but the sugar alcohol impregnated wood according to the present invention is not damaged by ants. 3. Automatic operation is possible because the impregnation concentration can be controlled by temperature. 4. High dimensional stability. High dimensional stability can be maintained even when processing fragile relics. 5. Since it has low hygroscopicity, it is stable against environmental changes after storage treatment. 6. There is little risk of contraction change due to sudden concentration change.
As a result, the impregnation period can be significantly shortened, the treatment period can be shortened, and the treatment process can be simplified.

Claims (2)

[Claims] 1. A water-immersed organic relic is immersed in a saturated aqueous solution of sugar alcohol, and the temperature of the saturated aqueous solution is sequentially increased from room temperature to 6
A method for preserving a water-immersed organic residue, which comprises raising the temperature to 0 to 80 ° C. to impregnate the water-immersed organic residue with a sugar alcohol, and then removing the water-immersed organic residue from the saturated aqueous solution and drying. 2. The water immersion method according to claim 1, wherein the sugar alcohol is initially charged in excess so that the saturated aqueous solution of the sugar alcohol always maintains the saturated state of the sugar alcohol even when the temperature rises. Preservation method of organic relics.