JPH01306202A - Preparation of modified wood - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention particularly relates to a method for producing modified wood having excellent dimensional stability and weather resistance, which is industrially very advantageous.

[Prior art] Wood is light, strong, and easy to process, so it has been used for a wide range of purposes, including building materials and furniture materials. The disadvantage was that it was subject to change. Furthermore, wood used for outdoor purposes such as exterior wall materials, eaves, and rain shutters is susceptible to deterioration due to ultraviolet rays in sunlight, moisture, oxygen, etc., and has problems in weather resistance.

As a means to improve the dimensional stability and weather resistance of the above-mentioned wood, a method has been used in which a chemical substance is injected into the wood and the wood is reacted with heat to modify the wood.

However, such heat treatment methods mainly apply heat from the outside of the object to be heated, first heating the surface and then heating the inside by heat conduction.

Therefore, when heat treating large pieces of wood such as planks or pillars, even if the surface of the wood can be treated, it takes a long time to process the inside of the wood as much as possible, and during that time the surface is heated. However, there was a problem of discoloration and deterioration. Further, in this case, since the chemical treatment is performed from the surface, there is a problem that it becomes difficult to remove the unreacted solution inside the wood during the process of collecting the unreacted solution by suction and vacuum.

[Problems to be solved by the invention] The present invention chemically treats large pieces of wood, such as planks and pillars, to the inside as much as possible, so that the surface does not discolor, deteriorate, or crack, and has particularly excellent dimensional stability and weather resistance. The object of the present invention is to provide a method for producing modified wood that is industrially very advantageous.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present inventors have conducted repeated research with the aim of finding an industrially advantageous method for obtaining modified wood with excellent performance. The wood impregnated with a reaction solution consisting of a polybasic acid anhydride and an epoxy compound is then separated from the excess reaction solution that was not impregnated into the wood during the impregnation process, and then the wood impregnated with the reaction solution is subjected to high frequency treatment. By heating the wood to a temperature of 40 to 160°C and alternately adding a polybasic acid anhydride and an epoxy compound to the hydroxyl groups of the wood components present in the wood, chemical modification can be carried out from within the wood. We have discovered that modified wood with particularly excellent dimensional stability and weather resistance can be obtained industrially advantageously.

In addition, the wood impregnated with the above reaction solution is heated using high frequency,
By vacuuming the unreacted solution while chemically modifying it or after chemically modifying it, the unreacted solution is heated from the inside, efficiently vaporized and recovered, and the polybasic acid anhydride produced as a side reaction product during the heating process. They have discovered that by allowing oligomers of epoxy compounds and epoxy compounds to exist in the treated wood, it is possible to economically advantageously obtain modified wood that exhibits even better effects, particularly in terms of dimensional stability.

That is, in the present invention, when impregnating wood with the reaction solution prior to chemical modification, the excess reaction solution that was not impregnated is separated, which leads to long-term stability of the separated and recovered reaction solution. It has the feature of enabling continuous or cyclical use of the reaction solution, and by using high frequency, it is possible to treat large pieces of wood such as planks and columns as deep as possible, has good thermal efficiency, and has a short reaction time. In addition, since the temperature in the center of the wood is somewhat higher than that in the surface layer, the recovery of unreacted solution by suction and vacuum can be easily carried out with less damage such as cracks. This provides a manufacturing method suitable for industrial production.

The wood used in the present invention is one that retains the tissue structure of wood. Various shapes are used, such as columnar, plate-like, or block-like, and are particularly suitable for large pieces of wood such as planks and columns. There are also no particular restrictions on tree species.

There are no particular restrictions on the polybasic acid anhydride, but specific examples include phthalic anhydride, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, itaconic anhydride, Examples include het acid and pyromellitic anhydride. Particularly preferred are phthalic anhydride, maleic anhydride, succinic anhydride, etc., which are industrially advantageous and have a low concentration. Among them, phthalic anhydride is particularly preferred because it has a large wood-modifying effect.

Epoxy compounds used in the present invention are not particularly limited, but include epichlorohydrin, methyl glycidyl ether, ethyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate, phenyl glycidyl ether, styrene oxide, olefin oxide, butyl glycidyl ether. , talesyl glycidyl ether, bisphenol A glycidyl ether, glycerin diglycidyl ether, and the like. Particularly preferred are epichlorohydrin, methyl glycidyl ether, ethyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate, and styrene oxide, which are industrially produced in large quantities and have relatively small molecular weights and low boiling points. Among them, epichlorohydrin is used for wood modification. It is highly effective and preferable.

Next, the manufacturing method of the present invention will be explained step by step. First, wood in the form of columns, plates, blocks, etc. is preferably used with a wood moisture content of 15% or less in order to facilitate chemical modification and in relation to the chemicals used.

On the other hand, a mixed solution of a polybasic acid anhydride and an epoxy compound is used as the reaction solution. The mixing ratio is preferably adjusted so that the molar ratio of the polybasic acid anhydride to the epoxy compound is 1=1 to 30.

The reason why such an epoxy compound is used in excess compared to the polybasic acid anhydride is that the epoxy compound acts as a solvent for the polybasic acid anhydride, and also because of the esterified wood produced in the intermediate stage of chemical treatment. This is because it has the effect of increasing the degree of addition of the epoxy compound to the carboxyl group of the side chain of and lowering the acid value of the modified wood. In addition, the mixed solution is
Generally, it can be prepared without a solvent, but depending on the type of polybasic acid anhydride, it may not be possible to dissolve it. In that case, it is preferable to prepare using a solvent such as dimethylformamide or dimethyl sulfoxide. . In addition, the ring-opening esterification reaction between the hydroxyl groups in wood and polybasic acid anhydrides, and the addition esterification reaction between the side chain carboxyl groups generated by this ring-opening esterification reaction and epoxy compounds, are carried out without catalyst. However, to accelerate the reaction, acidic catalysts such as sulfuric acid, perchloric acid, para-toluenesulfonic acid, etc., or basic catalysts such as sodium carbonate, dimethylbenzylamine, pyridine, etc. may be used. good.

In order to impregnate wood with the reaction solution prepared as described above, for example, the wood is immersed in the reaction solution, or the reaction solution is applied to the wood under reduced pressure, under increased pressure, or under reduced pressure. A method such as injection can be used.

Next, the reaction solution-impregnated wood obtained by the above method and the excess reaction solution that was not impregnated into the wood are separated, and then only the reaction solution-impregnated wood is placed in a high-frequency heating device, electrode plates are placed above and below, and a frequency It is heated by applying high frequency waves of 5 to 27 M11z. In this heating method, the reaction solution impregnated into the wood itself generates heat, so the wood is heated from the inside and can be uniformly modified, and the heat efficiency is very high, so the reaction time can be shortened. Heating is 40-160℃
Must be done at ℃. This is because when the kneading temperature is below 40°C, the above-mentioned reaction hardly progresses, and when the temperature exceeds 160°C, disadvantages such as discoloration and deterioration of the wood occur. Although the heating time varies depending on the type of polybasic acid anhydride or epoxy compound, the reaction temperature, and the shape and dimensions of the wood, it can be considerably shorter than the external heating method.

After heating the wood impregnated with the above reaction solution and chemically modifying it,
The inside of the reaction vessel is suctioned and depressurized at a vacuum level higher than 50 nonJ, for example, to lower the boiling point of the unreacted solution in the treated wood and vaporize it, and the unreacted solution is recovered by cooling and liquefying it outside the reaction vessel. . In the high-frequency heating method, the temperature of the central part of the wood is slightly higher than that of the surface layer, so the unreacted solution can be efficiently recovered by suction and vacuum. Also, there is less damage such as cracking of the wood. After suctioning for a predetermined period of time, the modified wood taken out from the reaction vessel becomes a product as it is, and there is no need to wash or dry it again.

The modified wood thus obtained has a small acid value. This is due to the higher molar concentration of the epoxy compound than the polybasic acid anhydride present in the reaction m (ri), so that most of the side chain carboxyl groups in the esterified wood obtained in the intermediate stages of this chemical treatment are simultaneously , which indicates that an addition esterification reaction occurred with the epoxy group in the epoxy compound.

In addition, in the infrared absorption spectrum of the modified wood, characteristic absorptions of adducts of polybasic acid anhydrides and epoxy compounds were clearly seen, which also indicates that ring-opening esterification and addition esterification reactions occurred. It shows.

As mentioned above, the purpose of adding an epoxy compound to a carboxyl group is to add a highly hydrophobic epoxy compound residue to a hydrophilic carboxyl group, thereby reducing its hydrophilicity.

[Effects of the Invention] As described above, the production method of the present invention improves the stability of the reaction solution in order to separate the excess reaction solution that is not impregnated when the wood is impregnated with the reaction solution prior to chemical modification. Since the impregnated wood is chemically modified using high frequency waves, it can be treated evenly inside the wood, and the heat is more efficient and the reaction is more efficient than with conventional external heating methods. Time can be shortened. Furthermore, since the temperature of the central part of the wood is somewhat higher than that of the surface layer, it is easy to recover unreacted solution by suction and vacuum, and there is little damage such as cracking, making this a very advantageous method industrially.

On the other hand, the modified wood obtained by the production method of the present invention has particularly excellent dimensional stability, has a lower swelling rate due to moisture absorption than untreated wood, and has a very high anti-swelling (anti-shrinkage) rate (ASE). It has excellent long-term dimensional stability.

The reason for the excellent dimensional stability is the effect of reducing the number of hydroxyl groups by esterification and blocking with the hydroxyl groups in wood that have moisture adsorption ability, that is, the blocking effect, and the swelling of wood due to the cell wall structure. This is due to the effect that when the bulky substituent groups of polybasic acid anhydrides and epoxy compounds enter the water-permeable parts of the wood, the room for adsorbed water to enter is reduced.

Furthermore, in terms of weather resistance, the modified wood of the present invention is superior to untreated wood, with very little discoloration and deterioration. The reason for this excellent weather resistance is the same as mentioned above.

The modified wood obtained by the manufacturing method of the present invention suppresses dimensional changes due to moisture, which is a disadvantage of wood, without impairing the excellent characteristics of wood, and suppresses the dimensional changes caused by moisture in the sunlight.
It has become possible to suppress deterioration caused by moisture, oxygen, etc. Further, as a secondary effect, it can be expected to prevent or suppress wood decay and damage caused by various wood-decaying fungi, termites, and the like.

As described above, the modified wood having excellent properties obtained by the production method of the present invention is suitable for construction materials, furniture materials, and many other fields, such as columns, beams, foundations, and base materials. It is used for floors, eaves, shutters, exterior wall materials, desks, bookshelves, etc.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited to the Examples.

Fruit 71 & Example 1 Dried cypress wood (hereinafter referred to as dried wood) measuring 3 cm in the tangential direction x 3 cm in the radial direction x 12 cm in the fiber direction was mixed with 24.1 g of phthalic anhydride and 225.8 g of epichlorohydrin.
g (Molar ratio of phthalic anhydride and epichlorohydrin: 1:
15) under reduced pressure (25 m
Suction was performed for 1 hour at a pressure of 12,5 mHg).
kg/cm2) for 30 minutes to impregnate the wood with the reaction solution. Next, this impregnated wood was taken out of the reaction solution, placed in a high frequency reactor, with electrode plates placed above and below, and high frequency was applied at a frequency of 6.7 MHz and an output of 3 kW. After heating at an internal temperature of 80°C for 3 hours,
Further, while heating at 110° C. for 3 hours, suction and vacuum were applied at 50 mmH3 to remove unreacted solution to obtain modified wood. The weight increase rate of phthalic anhydride and epichlorohydrin in this modified wood was 33.3% by weight based on the wood.

Example 2 The injection conditions of Example 1 were changed to under reduced pressure (20 mm mm 1 liter for 1 hour, and then under increased pressure (6.5 kg/cm2) for 1 hour.
In addition, modified wood was obtained in the same manner as in Example 1 except that the heating conditions were changed to an internal temperature of 110° C. for 2 hours. The weight increase rate of phthalic anhydride and epichlorohydrin in this modified wood was 33.1% by weight based on the wood.

Example 3 Dry wood was immersed in a reaction solution consisting of 18.5 g of phthalic anhydride and 231.1 g of epichlorohydrin (molar ratio of phthalic anhydride and epichlorohydrin 1.20), and suction was applied under reduced pressure (20 mmHg) for 10 minutes. conduct,
Further, it was heated under pressure (20 kg/cm') for 20 minutes,
The reaction solution was impregnated into the wood. Next, this impregnated wood was taken out of the reaction solution, placed in a high frequency reactor with electrode plates sandwiched above and below, and high frequency was applied at a frequency of 8.7 MHz and an output of 3 kW. After heating at an internal temperature of 110° C. for 1 hour, the mixture was further heated at 110° C. for 6 hours while vacuuming with 50 mm) Ig was applied to remove unreacted solution to obtain modified wood. The weight increase rate of phthalic anhydride and epichlorohydrin in this modified wood was 34.0% by weight based on the wood.

Example 4 Dry wood was soaked in a reaction solution consisting of 13.5 g of maleic anhydride and 235.7 g of allyl glycidyl ether (molar ratio of maleic anhydride to allyl glycidyl ether: 1:15), and the mixture was soaked under reduced pressure (20 mmHg). Suction was carried out for 1 hour, and injection was continued for 1 hour under pressure (6.5 kg/cm2) to impregnate the wood with the reaction solution. This impregnated wood is then reacted with t8? & Take it out from inside, put it in a high frequency reaction device, sandwich the electrode plates on the top and bottom, and set the frequency to 6.
High frequency was applied at 7 MHz and an output of 3 kW. After heating at an internal temperature of 120° C. for 30 minutes, the mixture was further heated at 120° C. for 3 hours while suction and vacuum was applied to 50 mm and 11 g to remove unreacted solution to obtain modified wood.

The weight increase rate of allyl maleic anhydride glycidyl ether in this modified wood is 23.7% by weight based on the wood.
Met.

Comparative Example 1 Dry wood was immersed in a reaction solution consisting of 24.1 g of phthalic anhydride and 225.8 g of epichlorohydrin (molar ratio of phthalic anhydride to epichlorohydrin: 115), suctioned under reduced pressure (20n++nl 1g) for 1 hour, and further heated. The wood was injected under pressure (6.5 kg/crB for 1 hour) to impregnate the wood with the reaction solution.Then, the impregnated wood was taken out of the reaction solution, placed in a reaction vessel, and heated at 110°C for 3 hours using an external heating method. After heating at 110°C for 6 hours, the suction pressure was reduced to 20 + nmHg.Then, the modified wood was thoroughly dried using air drying and a hot air dryer at 105°C. The weight increase rate of phthalic anhydride and epichlorohydrin in this modified wood was 35.3% by weight based on the wood.

Comparative example 2 Untreated dried wood was used as a comparative example.

(Physical property test of modified wood) The modified wood obtained in Examples 1 to 4, the wood modified by the external heating method of Comparative Example 1, and the untreated wood of Comparative Example 2 were subjected to a physical property test.

The weight increase rate was expressed as the total amount of the polybasic acid anhydride and the epoxy compound in % by weight based on the wood.

The moisture absorption test was conducted as follows. That is, after measuring the weight and dimensions of a completely dry test piece in a hot air dryer at 105°C,
In a desiccator at 23℃ containing a saturated aqueous solution of 1 (75℃
%RH) and absorb moisture until a constant weight is reached.
The boiling rate and swelling rate (tangential and radial directions) were determined.

The dry water repeated test was conducted as follows. That is, 105℃
After drying completely in a hot air dryer and measuring the dimensions of the test piece, immerse it in distilled water and reduce the pressure (20 mmHg) for 30 minutes.
L, left for 22 hours. Thereafter, these were taken out, the dimensions of the water-absorbed test pieces were measured, and the anti-swelling ratio was determined.

Next, these water-absorbed test pieces were dried at 40°C for 4 hours and then at 105°C for 20 hours, and the dimensions of the test pieces were measured to determine the anti-acid shrinkage ratio. In addition, the anti-swelling (anti-shrinkage) rate (
ASE) is defined by the following equation.

Here, VC represents the volumetric swelling (shrinkage) rate of untreated wood, and Vt represents the volumetric swelling (shrinkage) rate of treated wood.

As is clear from the results in Table 1, the modified wood manufactured by the method of the present invention in Examples 1 to 4 had less discoloration than the externally heat-treated wood in Comparative Example 1, and It has superior dimensional stability compared to untreated wood,
It was clear that the effects of the present invention were recognized.

Example 5 Tangential direction focmX Radial direction 10cmX Fiber direction 20c
m dry wood was immersed in a reaction solution consisting of 342.8 g of phthalic anhydride and 4282.5 g of epichlorohydrinic acid (molar ratio of phthalic anhydride and epichlorohydrin 1:20), and suction was applied under reduced pressure (20+nmHg) for 10 minutes. The mixture was further injected for 20 minutes under pressure (20 kg/cm2) to impregnate the wood with the reaction solution. Then react this impregnated wood? 8. Take it out from the liquid, put it in a high frequency reaction device, put electrode plates on the top and bottom, and the frequency is 6.7 M)
Iz, high frequency was applied with an output of 3 kW. Internal temperature 11
After heating at 0℃ for 1 hour, further heating at 110℃
While heating for 15 hours, suction and vacuum were applied with 50 mm) Ig to remove the unreacted solution to obtain modified wood. The weight increase rate of phthalic anhydride and epichlorohydrin in this modified wood was 32.1% by weight based on the wood.

Comparative Example 3 Dry wood measuring 10 cm in the tangential direction, 10 cm in the radial direction, and 20 cm in the fiber direction was immersed in a reaction solution consisting of 342.8 g of phthalic anhydride and 4282.5 g of epichlorohydrin (molar ratio of fi hydrophthalic acid epichlorohydrin 1.20). Suction was performed under reduced pressure (20 mm 1 g) for 10 minutes, and then under increased pressure (20 kg/cm2) for 20 minutes.
The mixture was injected for a minute to impregnate the wood with the reaction solution. Next, this impregnated wood was taken out of the reaction solution, placed in a reaction container, heated at 110°C for 1 hour using an external heating method, and then vacuumed at 50 mm and 11 g while heating at 110°C for 20 hours. went. Thereafter, the wood was sufficiently dried using air drying and a hot air dryer at 105° C. to obtain a modified wood. The weight increase rate of phthalic anhydride and shrimp chlorophyll in this modified wood is 49.7% based on the wood.
% by weight.

(Physical property test of modified wood) The results of the physical property test of the modified wood obtained in Example 5 and the wood treated by external heating of Comparative Example 3 are shown in Table 2.

Table 2 As is clear from the results in Table 2, the modified wood obtained by the production method of the present invention in Example 5 had a low residual acid value on the surface and inside, the treatment was uniform, and oligomers were present. but,
Almost no unreacted solution remains. On the other hand, in the wood treated by external heating in Comparative Example 3, the residual acid value inside was high, and a considerable weight loss was observed due to the acetone extraction and cleaning. This is thought to be due to the fact that In this way, the external heating method treats the wood from the surface, so
While it is difficult to remove the unreacted solution inside, the high-frequency heating method uniformly processes from the inside, so the unreacted solution is efficiently removed, and the effects of the present invention are observed without discoloration or cracking. That is clear.

Claims (2)

[Claims] (1) Impregnate wood with a reaction solution consisting of a polybasic acid anhydride and an epoxy compound, then separate the wood impregnated with the reaction solution and the excess reaction solution that was not impregnated into the wood during the impregnation process, and then perform the reaction. Solution impregnated wood using high frequency 4
A method for producing modified wood, which comprises heating the wood to a temperature of 0 to 160°C to alternately add a polybasic acid anhydride and an epoxy compound to the hydroxyl groups of wood components present in the wood. (2) Impregnate wood with a reaction solution consisting of a polybasic acid anhydride and an epoxy compound, then separate the wood impregnated with the reaction solution and the excess reaction solution that was not impregnated into the wood during the impregnation process, and then proceed with the reaction. Solution impregnated wood using high frequency 4
By heating to a temperature of 0 to 160 degrees Celsius, while or after chemical modification, and vacuuming the unreacted solution, the unreacted solution is vaporized and recovered, and the polybase produced as a side reaction product during the heating is A method for producing modified wood, characterized in that an oligomer of an acid anhydride and an epoxy compound is present in the treated wood.