MULTIFUNCTIONAL WOOD PRESERVATIVE COMPOSITION AND WOOD PRESERVATION TREATMENT METHOD USING THE SAME

Abstract

The present invention relates to a multifunctional wood preservative composition containing a compound prepared by reaction of hydrazine hydrate and boric acid and to a method for wood preservation treatment using the same.

The wood preservative composition of the present invention can not only impart flame retardant, insect-repellent, rot-resistant, insect-repellent, and rust-proof effects to wood, such as various wooden structures including wooden cultural assets, but also causes no whitening and makes relatively fewer color changes for dancheong. Furthermore, the wood preservative composition of the present invention is provided as a one-component type liquid and thus can save time and costs for wood treatment and is convenient to use.

Claims

1. A method for wood preservation treatment, the method comprising treating wood with a wood preservative composition comprising a compound prepared using hydrazine hydrate and boric acid at a reaction molar ratio of 1:1-10.

2. The method of claim 1, wherein the compound includes at least one selected from a stereoisomer thereof or a salt thereof.

3. The method of claim 1, wherein the composition further comprises a surfactant and a flame-retardant aid.

4. The method of claim 1, wherein the composition comprises 3 wt % to 70 wt % of the compound, 0.01 wt % to 5 wt % of a surfactant, and 0 wt % to 15 wt % of a flame-retardant aid.

5. The method of claim 4, wherein the surfactant is at least one selected from the group consisting of an anionic surfactant, a cationic surfactant, and a non-ionic surfactant.

6. The method of claim 5, wherein the anionic surfactant is at least one selected from the group consisting of an alkali salt of dodecylbenzenesulfonic acid, an alkali salt of an alpha-olefin sulfonic acid, an alkali salt of an alkyl benzene sulfonic acid, an alkali salt of a dialkylsulfosuccinic acid; an alkali salt of an alkyl phosphate, an alkali salt of an aminophosphonic acid, an alkali salt of an alkyl naphthalene acid, and an alkali salt of an alkyl allyl ether.

7. The method of claim 5, wherein the cationic surfactant is at least one selected from the group consisting of a quaternary ammonium salt having a structure of an alkyl group or aromatic group with 8 to 18 carbon atoms, a fatty acid amine acetate with 8 to 18 carbon atoms, a fatty acid imidazolium methosulfate with 12 to 18 carbon atoms, and a fatty acid imidazolium quaternary compound with 8 to 18 carbon atoms.

8. The method of claim 5, wherein the non-ionic surfactant is at least one selected from the group consisting of an alkyl phenol with 6 to 12 carbon atoms, a fatty acid ester with 12 to 18 carbon atoms, a fatty acid ether with 12 to 18 carbon atoms, a trisiloxane, and an acetylene-structured ethylene oxide adduct, and an amine oxide with 12 to 18 carbon atoms.

9. The method of claim 4, wherein the flame-retardant aid is at least one selected from the group consisting of phosphoric acid or a salt thereof, sulfuric acid or a salt thereof, a halogen acid or a salt thereof, sulfamic acid or a salt thereof, boric acid or a salt thereof, and a phosphonic acid or a salt thereof.

10. The method of claim 9, wherein the salt of phosphoric acid is at least one selected from the group consisting of monoammonium phosphate, diammonium phosphate, triammonium phosphate, monolithium phosphate, dilithium phosphate, trilithium phosphate, monosodium phosphate, disodium phosphate, trisodium phosphate, monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monoguanidine phosphate, diguanidine phosphate, a low-condensed ammonium polyphosphate with a condensation degree of 2-200, guanyl urea phosphate, an amine salt of phosphoric acid, and a hydrazine salt of phosphoric acid.

11. The method of claim 9, wherein the salt of sulfuric acid is at least one selected from the group consisting of ammonium sulfate, lithium sulfate, sodium sulfate, potassium sulfate, an amine salt of sulfuric acid, and a hydrazine salt of sulfuric acid.

12. The method of claim 9, wherein the salt of the halogen acid is at least one selected from the group consisting of ammonium chloride, lithium chloride, sodium chloride, potassium chloride, ammonium bromide, sodium bromide, potassium bromide, an amine salt of the halogen acid, and a hydrazine salt of the halogen acid.

13. The method of claim 9, wherein the salt of sulfamic acid is at least one selected from the group consisting of guanidine sulfamate, ammonium sulfamate, lithium sulfamate, sodium sulfamate, potassium sulfamate, an amine salt of sulfamic acid, and a hydrazine salt of sulfamic acid.

14. The method of claim 9, wherein the salt of boric acid is at least one selected from the group consisting of boric acid, borax, boron oxide, potassium pentaborate (KB5O7), potassium tetraborate (K2B4O7), sodium metaborate (NaBO2), ammonium pentaborate ((NH4)2B10O16.Math.8H2O), sodium octaborate (Na2B8O13), lithium octaborate (Li2B8O13), magnesium octaborate (MgB8O13), calcium octaborate (CaB8O13), and an amine salt of boric acid.

15. The method of claim 9, wherein the salt of phosphonic acid is at least one selected from the group consisting of amino trimethylene phosphonic acid, 1-hydroxyethylene-1,1-diphosphonic acid, ethylene diamine tetramethylene phosphonic acid, hexamethylene diamine tetramethylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid.

16. The method of claim 1, wherein the composition has at least one effect selected from the following: i) flame-retardant effect; ii) discoloration-resistant effect; iii) whitening-resistant effect; iv) mold-proof effect; v) rot-resistant effect; vi) insect-repellent effect; and vii) iron corrosion inhibiting effect.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0088] FIG. 1 shows infrared spectra of white powders obtained by evaporating and concentrating solutions, synthesized under conditions of #1 (left) and #2 (right) of Example 1, at 60° C. by an evaporation concentrator.

[0089] FIG. 2 shows X-ray diffraction spectra of white powders obtained by evaporating and concentrating solutions, synthesized under conditions of #1 (left) and #2 (right) of Example 1, at 60° C. by an evaporation concentrator.

[0090] FIG. 3 shows an X-ray diffraction (XRD) pattern of a powder obtained by drying the solution, synthesized under conditions of #2 of Example 1, at room temperature for 4 months.

[0091] FIG. 4 shows an XRD pattern of transparent crystals formed in the solution synthesized under conditions of #2 of Example 1 by leaving the solution at room temperature for 4 months.

[0092] FIG. 5 is a photograph showing the change in the appearance of wood according to the type of drug.

DETAILED DESCRIPTION OF THE INVENTION

[0093] Hereinafter, preferable exemplary embodiments will be described for better understanding of the present invention. However, the following exemplary embodiments are provided merely to illustrate the present invention and not to restrict the scope of the present invention. The exemplary embodiments of the present invention are provided to illustrate the present invention more completely to those skilled in the art.

Example 1: Synthesis of Hydrazine Borate

[0094] Hydrazine borates (#1 to #6) were synthesized by varying the amounts of boric acid (BA) and hydrazine hydrate (HH) while fixing the boric acid equivalent (BAE) level to 30 wt %.

[0095] Specifically, 150 g of BA was added, and HH was added at ratios shown in Table 1 after addition of water (distilled water), followed by reaction at a temperature of each reaction solution of 60° C. The termination time point of the reaction was when the solution became a transparent solution. The degree of precipitation was analyzed one day after the completion of the reaction.

TABLE-US-00001 TABLE 1 BA:HH reaction Reaction molar Distilled Total Precipitate No. ratio BA HH water amount pH formation*.sup.1 #1 1:1 150 g 121.5 g 228.5 g 500 g 9.50 x #2 2:1 150 g  60.8 g 289.2 g 500 g 8.42 x #3 3:1 150 g  40.5 g 309.5 g 500 g 7.45 ○ #4 4:1 150 g  27.5 g 322.5 g 500 g 6.13 ○ #5 5:1 150 g  24.3 g 325.7 g 500 g 6.33 ○ #6 6:1 150 g  20.3 g 329.7 g 500 g 6.59 ○ *.sup.1: x: No precipitates, ○: Precipitate formation

[0096] As a result, #1 and #2 resulted in transparent solutions, and #3 to #6 showed precipitate formation, identifying that as the proportion of boric acid in the ratio of BA and HH increase, the amount of precipitates increases. As a result of recovering and analyzing precipitates, all of the precipitates were BA.

[0097] The compound containing 1:1 of BA and HH had 65.9% BAE and the compound containing 2:1 of BA and HH had 79.4% BAE.

[0098] Then, as a result of evaporating and concentrating #1 and #2 at 60° C. by an evaporative concentrator, white solids corresponding to 28.7% and 23.9% of the weights of the raw specimens were obtained, and the infrared spectrum and X-ray diffraction (XRD) measurement results of these solids are shown in FIGS. 1 and 2, respectively. CHN elemental analysis results thereof are shown in Table 2 below.

TABLE-US-00002 TABLE 2 C H N #1 of Example 1 0.34 5.71 27.1 0.42 5.60 27.1 Average 0.38 5.66 27.10 #2 of Example 2 0.36 4.85 20.1 0.42 4.86 20.1 Average 0.39 4.86 20.10

[0099] As a result, it was identified that BA and HH reacted at a molar ratio of 2:1 [H.sub.2N.sub.2.Math.2H.sub.3BO.sub.3], indicating that an excess of HH was present in #1.

[0100] Meanwhile, the XRD pattern measurement results of a powder obtained by drying the solution synthesized under the conditions with respect to #2 at room temperature for 4 months are as shown in FIG. 3.

[0101] The XRD pattern measurement results of transparent crystals formed by leaving the solution synthesized under the conditions with respect to #2 at room temperature for 4 months are shown in FIG. 4.

Example 2: Synthesis of Hydrazine Borates with Different Boric Acid Equivalent (BAE) Levels

[0102] Hydrazine borates (#7 to #11) with different BAE levels were synthesized by varying the amounts of BA and HH. Specifically, BA was added at proportions shown in Table 3 below, and water was added and HH was added, followed by reaction at a temperature of each reaction solution of 60° C. Then, the termination time point of the reaction was when the solution became a transparent solution. The degree of precipitation was analyzed one month after the completion of the reaction.

TABLE-US-00003 TABLE 3 Total Reaction amount No BAE BA (g) HH (g) Water (g) (g) pH #7  40 wt % 100.0 40.6 109.4 250 8.45 #8  50 wt % 125.0 50.7 74.3 250 8.42 #9  55 wt % 137.5 55.7 56.8 250 8.41 #10 60 wt % 150.0 60.8 39.2 250 8.40 #11 71 wt % 178.3 71.7 0 250 8.37

[0103] As a result, all of the solutions were transparent solutions immediately after being prepared, but one month after the preparation, insoluble matter was deposited on the bottom in #9, #10, and #11, while colorless and transparent solutions were maintained in #7 and #8, indicating that a hydrazine borate solution was stable up to 50 wt % BAE at room temperature.

Preparative Example 1: Preparation of Wood Preservative Composition

Preparative Example 1-1: Preparation of Wood Preservative Composition (Example 3)

[0104] A wood preservative composition was prepared by adding 2 g of a 50% benzalkonium chloride solution to 100 g of a solution in which the hydrazine borate solution of #8 in Example 2 was diluted to 20 wt % BAE in distilled water.

Preparative Example 1-2: Preparation of Wood Preservative Composition (Example 4)

[0105] A wood preservative composition was prepared by adding diammonium phosphate in a content of 5 wt % on the basis of a solid content and a 0.5% sodium dodecyl benzene sulfonate anionic surfactant to 100 g of a solution in which the hydrazine borate solution of #8 in Example 2 was diluted to 20 wt % BAE in distilled water.

Preparative Example 1-3: Preparation of Wood Preservative Composition (Example 5)

[0106] A wood preservative composition was prepared by adding disodium octaborate tetrahydrate (DOT, Na.sub.2B.sub.8O.sub.13.Math.4H.sub.2O) in a content of 7 wt % on the basis of a solid content and a 1.0% sodium α-olefin sulfonate anionic surfactant to 100 g of a solution in which the hydrazine borate solution of #8 in Example 2 was diluted to 20 wt % BAE in distilled water.

Preparative Example 1-4: Preparation of Wood Preservative Composition (Example 6)

[0107] A wood preservative composition was prepared by adding ammonium amino trimethylene phosphonate in a content of 3 wt % on the basis of a solid content and a 1.0% Dynol 604 non-ionic surfactant to 100 g of a solution in which the hydrazine borate solution of #8 in Example 2 was diluted to 20 wt % BAE in distilled water.

Preparative Example 1-5: Preparation of Wood Preservative Composition Containing Phosphoric Acid Salt as Main Ingredient (Comparative Example 1)

[0108] A colorless transparent wood preservative composition having pH of 7.37 and containing triethanolamine as a main ingredient was prepared by placing 50.0 g of 85% phosphoric acid and 84.3 g of distilled water in a 500 mL beaker and adding 115.7 g of triethanolamine for 3 hours.

Preparative Example 1-6: Preparation of Wood Preservative Composition Containing Ammonium Salt as Main Ingredient (Comparative Example 2)

[0109] A wood preservative composition was prepared by diluting ammonium nitilotis(methylene)trisphosphonate (Amgard RD-1, Rhodia) to a solid content of 20% in distilled water.

Preparative Example 1-7: Preparation of Wood Preservative Composition Having Boric Acid Salt as Main Ingredient (Comparative Example 3)

[0110] In a 1 L beaker, 240 g of ethylene glycol and 60 g of polyethylene glycol were placed and mixed, and then the temperature was raised to 45° C. In this situation, mixing was conducted while 200 g of DOT was slowly added, and the temperature was raised to 90° C. while the mixture was stirred well. Thereafter, the mixture was heated until it became a transparent solution. After the solution was confirmed to be transparent, the solution was cooled to room temperature to thereby prepare 500 g of a wood preservative composition having an effective boric acid content of 48.0% and a high viscosity.

Preparative Example 1-8: Preparation of Wood Preservative Composition Having Sulfamic Acid Salt as Main Ingredient (Comparative Example 4)

[0111] After guanidine sulfamate was diluted to a solid concentration of 30% in distilled water, a 1.0% distearyl dimethyl benzyl ammonium bromide as a cationic surfactant was added thereto to thereby prepare a wood preservative composition having guanidine sulfamate as a main ingredient.

[0112] The ingredients of the wood preservative compositions of Examples 3 to 6 and Comparative Examples 1 to 4 are shown in Table 4 below.

TABLE-US-00004 TABLE 4 Hydrazine borate Surfactant Flame-retardant aid Example Hydrazine borate Benzalkonium — 3 solution #8 chloride Example Hydrazine borate Salt of Ammonium 4 solution #8 dodecylbenzenesulfonic phosphate acid Example Hydrazine borate Sodium alpha-olefin DOT 5 solution #8 sulfonate Example Hydrazine borate Dynel 604 Ammonium amino 6 solution #8 trimethylene phosphonate Comparative — — Triethanolamine Example phosphate 1 Comparative — — Ammonium Example nitrilotris(methylene)tris- 2 phosphonate Comparative — — DOT Example 3 Comparative — Distearyl dimethyl Guanidine sulfamate Example benzyl ammonium 4 chloride

Experimental Example 1: Test on Flame-Retardant Performance

[0113] The solutions of Examples 4, 5, and 6 were tested for flame-retardant performance.

[0114] Specifically, the wood preservative compositions of Examples 4, 5, and 6 were sprayed by using a simplified sprayer on surfaces of three sheets of plywood (specimens) of 190 mm in width, 290 mm in length, and 5 mm in thickness, corresponding to Grade 2 of KS F 3101 (normal plywood) once, respectively. The plywood sheets were left standing at room temperature for 48 hours, and then sprayed once more. The average throughput was 139.4 g/m.sup.2 for the first treatment and 111.3 g/m.sup.2 for the second treatment.

[0115] Thereafter, the flame-retardant performance was tested according to the “standards and methods for measuring flame-retardant performance of synthetic resin boards and plywood” of Article 7 of the “standards for flame-retardant performance (KOFEIS 1001)” by the Korea Fire Institute. According to the methods, after a sample is heated by a maker burner for 2 minutes and then the flame of the burner is removed, the time until a state of burning with flame stops is defined as “afterflame time”; the time until a state of burning without flame stops is defined as “afterglow time”; the area carbonized during the test is defined as “char area”; and the carbonized length is defined as “char length”. The acceptance standards according to KOFEIS 1001 are an afterflame time of 10 seconds or less, an afterglow time of 30 seconds or less, a char length of 20 cm or less, and a char area of 50 cm.sup.2 or less. The average values of the afterflame time, afterglow time, char time, and char area after the test on flame retardancy are shown in Table 5.

TABLE-US-00005 TABLE 5 Char area Char length Afterflame Afterglow (cm.sup.2) (cm) time (s) time (s) BAE (wt %) 24 34.7 8.7  4.5  0 18 38.6 9.2  3.4  0 12 38.4 9.6  4.0  0 Preservation treatment solution Example 4 37.0 8.9  1.0  0 Example 5 36.4 7.2  0.0  0 Example 6 42.3 8.0  2.5  0 No treatment 89.7 17.2 200↑ 200↑

[0116] The results identified that the untreated plywood was beyond the flame-retardant performance acceptance standards, but hydrazine borates having at least 12 wt % BAE or the wood preservative compositions of Examples 4, 5, and 6 showed excellent flame-retardant effects when used to treat plywood.

Experimental Example 2: Test on Discoloration Resistance

[0117] The hydrazine borate solution of #8 in Example 2 was diluted to an effective boric acid content of 20 wt %, and the diluted solution was sprayed on specimens, which were manufactured by printing Pinus densiflora wood samples of 70 mm in length, 150 mm in height, and 5 mm in thickness with 13 dancheong colors, respectively, or as a bare wood state of the wood sample. Spraying was conducted a total of two times by first spraying and, after 48 hours, second spraying. After the final spraying, the specimens were dried by standing vertically in a well-ventilated place for 7 days, followed by measurement. As for a control group, distilled water, not the preservative, was applied by way of the same method as above.

[0118] Regarding discoloration resistance, L*, a*, and b* values of each of the specimens before and after the treatment with the preservative were measured using a colorimeter, and the extents of change were compared by ΔL*, Δa*, Δb*, and ΔE* values. Of these, L*, a brightness index, is 100 for white and 0 for black, and a* and b*, chromacheckness indices, indicate hue and saturation. ΔE* was calculated using the equation below.

ΔE*=√{square root over ((ΔL*).sup.2+(Δa*)+(Δb*).sup.2)}

[0119] In the equation, ΔL*, Δa*, and Δb* are the changes of L*, a*, and b* before and after the preservative treatment.

[0120] The results of evaluation according to standards of the degree of color difference as shown in Table 6 below are shown in Table 7.

TABLE-US-00006 TABLE 6 Degree of color difference ΔE* Extremely small difference   0-0.5 Small difference 0.5-1.5 Perceptible difference 1.5-3.0 Significant difference 3.0-6.0 Extremely significant difference 6.0-12.0 Other colors 12.0 or more

TABLE-US-00007 TABLE 7 Color Color difference difference Dancheong color (ΔE*) Dancheong color (ΔE*) Blue green 0.61 Vermilion (juhong) 0.15 (noelog) Pea green 1.80 White (jidang) 0.07 (yanglog) Orange (jangdan) 1.24 Greenish brown 1.88 (hayeob) Navy blue 2.46 Reddish brown 1.94 (guncheong) (daja) Sky blue 1.87 Apricot (yugsaeg) 2.53 (samcheong) Chrome yellow 0.08 Black (meog) 0.04 (sukhwang) Brown (sukganju) 0.21 Bare wood 2.78 (baeggol)

[0121] The description in parentheses above is the Korean pronunciation in English.

Experimental Example 3: Test on Whitening Resistance

[0122] 5 g of seashell powder was added to 100 g of each of the solutions of #2 of Example 1 and Comparative Example 1. While the mixture was stirred at room temperature, a portion of solids was collected at regular time intervals, separated into solids and a liquid by a centrifuge, washed and dried three times, and then subjected to infrared spectrum measurement. The results of measuring the proportion of the original seashell powder and the produced calcium phosphate tribasic salt are shown in Table 8.

TABLE-US-00008 TABLE 8 30 Solution minutes 2 hours 8 hours 12 hours 72 hours #2 of Example 1  0%  0%  0%  0% 0% Comparative 10% 30% 90% 100% — Example 1

[0123] In addition, as a result of testing the solution of Comparative Example 2 in the same manner as above, the seashell powder was dissolved with bubbling of carbonic acid gas to change to a transparent solution. It was expected that the seashell powder was dissolved by a metal ion sequestering action of nitilotris(methylene)triphosphonic acid and thus was transparent.

[0124] Referring to Table 8, in the solution prepared in Comparative Example 1, calcium carbonate as a main component of seashell powder reacted with triethanolamine phosphate to start to change to calcium phosphate after 30 minutes, and all changed to calcium phosphate after 12 hours. However, in the hydrazine borate solution prepared in #2 of Example 1, the form of calcium carbonate was maintained even after 72 hours, indicating that hydrazine borate did not react with calcium carbonate and thus had an excellent whitening-resistant effect.

Experimental Example 4: Test on Mold-Proof Effect

[0125] For five species of test strains, Aspergillus niger (ASN), Penicillium funiculosum (PEC)], Rhizopus nigricans (RHN)], and Aureobasidium pullulans (AUP), and Tricoderma vidde (TRV), five species of reference strains isolated by the Forest Research Institute (FRI) were used.

[0126] The solution of Example 3 was sprayed onto specimens by way of the same method as in Experimental Example 3 so that the average amount of drug application was 120 g/m.sup.2 (6 specimens being used for each strain). After each strain was cultured at a temperature of 26° C.±2° C. and a relative humidity of 70-80% for 4 weeks, the growth condition of cells in each specimen was observed, and evaluation values were obtained according to the standards in Table 9 below, and the results are shown in Table 10.

TABLE-US-00009 TABLE 9 Evaluation value Growth condition of cells 0 No mold growth was observed in specimen. 1 Mold growth was observed on side of specimen. 2 Mold growth was observed on ⅓ or less of top surface of specimen. 3 Mold growth was observed on ⅓ or more of top surface of specimen.

TABLE-US-00010 TABLE 10 Terms ASN PEC RHN AUP TRV Example 3 0 0 0 0 0 No treatment 3 3 3 3 3

[0127] The results confirmed that in cases of no treatment, mold growth was observed on ⅓ or more of the top surface of the specimen regardless of the species of test strains, but in cases of treatment with the solution of Example 3, no mold growth was observed, showing excellent mold-proof effects.

Experimental Example 5: Test on Rot-Resistant Effect

[0128] The solution of Example 3 was tested on the brown rot fungus Tyromyces palustris and the white rot fungus T. versicolor for three weeks according to the test method specified in KS M-1701 Wood Preservatives (2010). Thereafter, the average weight reduction rates of specimens were obtained, and the results are shown in Table 11. According to KS M-1701, an average weight reduction rate of 3% or less is defined as the standard for achieving rot-resistant performance.

TABLE-US-00011 TABLE 11 Amount of chemical Average weight Classification Solution application (g/m.sup.2) reduction rate (%) White rot Example 3 110.4 0.19 fungus No treatment — — 4.95 Brown rot Example 3 111.0 0.00 fungus No treatment — — 5.82

[0129] The results confirmed that in cases of no treatment, the average weight reduction rates of the white rot fungus and the brown rot fungus were 4.95% and 5.82%, respectively, both of which exceed 3.0%. However, in cases of treatment with the solution of Example 3, the average weight reduction rates of the fungi were 0.19% and 0.00%, respectively, indicating excellent rot-resistant effects.

Experimental Example 6: Test on Insect-Repellent Effect

[0130] In a container, each specimen sprayed with the solution of Example 3 was placed and 200 animals of Reticulitermes speratus were placed, and then the container was left standing in a dark place at a temperature of 28° C.±2° C. and Reticulitermes speratus were grown for 3 weeks. The results of obtaining the insecticidal rate and the average weight reduction rate of each specimen are shown in Table 12. Herein, an average weight reduction rate of 3% or less was evaluated as having an insect-repellent effect.

TABLE-US-00012 TABLE 12 Average Amount of chemical Average weight insecticidal Solution application (g/m.sup.2) reduction rate (%) rate (%) Example 3 119.4 0.46 100.0 No treatment — 21.9 16.6

[0131] The results confirmed that in cases of no treatment, the average weight reduction rate and the average insecticidal rate were 21.9% and 16.6%, respectively. However, in cases of treatment with the solution of Example 3, the average weight reduction rate and the average insecticidal rate were 0.46% and 100.0%, respectively, indicating excellent insect-repellent effects.

Experimental Example 7: Test on Iron Corrosion

[0132] Two nails were driven at an interval of 10 mm into pine wood with a size of 200 mm in width, 40 mm in length, and 5 mm in thickness while the heads of the nails were placed upwards. The test nails are 38 mm in length defined according to KS D 3553, and degreased with benzene and washed with ethanol before use. Each of the solutions of Example 3 and Comparative Example 4 was applied at 110 g/m.sup.2 on wood. Each wood was placed in a desiccator (inner diameter of 18 cm) previously adjusted to a temperature of 40° C.±2° C. and a relative humidity of about 97% and containing a saturated aqueous solution coexisting with crystals of potassium sulfate while the heads of the nails were placed upwards. Each wood was left for 10 days while the temperature was maintained. After 10 days, the nails were pulled from each specimen and completely immersed in a beaker containing an aqueous solution of ammonium citrate (10%). The beaker was covered with a watch glass and then heated for 20 minutes. The nails were washed, wiped with a cloth, dried, and then weighed to 0.001 g. The weight reduction rate due to nail corrosion was calculated using the following equation.

[00001]$\mathrm{Weight}\mathrm{reduction}\mathrm{rate}\left(\%\right)=\frac{\mathrm{nail}\mathrm{weight}\mathrm{before}\mathrm{test}\left(g\right)-\mathrm{nail}\mathrm{weight}\mathrm{after}\mathrm{test}}{\mathrm{nail}\mathrm{weight}\mathrm{before}\mathrm{test}\left(g\right)}\times 100$

[0133] The iron corrosion rate was calculated using inserting the obtained weight reduction rate into the following equation, and these are shown in Table 13.

[00002]$\mathrm{Iron}\mathrm{corrosion}\mathrm{rate}\left(\%\right)=\frac{\mathrm{average}\mathrm{weight}\mathrm{reduction}\mathrm{rate}\mathrm{of}\mathrm{nail}\mathrm{of}\mathrm{treated}\mathrm{specimen}\left(\%\right)}{\mathrm{average}\mathrm{weight}\mathrm{reduction}\mathrm{rate}\mathrm{of}\mathrm{nail}\mathrm{of}\mathrm{untreated}\mathrm{specimen}\left(\%\right)}$

TABLE-US-00013 TABLE 13 Iron Amount of chemical Average weight corrosion Classification application (g/m.sup.2) reduction rate (%) rate Example 3 116.3 0.41 0.43 Comparative 118.2 1.68 1.75 Example 4 No treatment — 0.96 1.00

[0134] The results confirmed that compared with the untreated wood, the iron corrosion rate in the treatment with Example 3 containing hydrazine borate as an ingredient was 0.43, and the iron corrosion rate in the treatment with Comparative Example 4 containing guanidine sulfate as an ingredient was 1.75, indicating an excellent iron corrosion inhibiting effect of hydrazine borate.

Experimental Example 8: Test on Dilution Stability

[0135] As shown in Table 14, #2 of Example 2 having 50.0 wt % BAE and Comparative Example 3 having an effective boric acid content of 48.0 wt % were diluted in distilled water, and 40 mL of each was placed in a 50 mL polyethylene tube. The precipitation or lack thereof over time was visually observed while the tube was shaken every 6 hours, and the results are shown in Table 14.

TABLE-US-00014 TABLE 14 1:1 2:1 3:1 Elapsed #2 of Comparative #2 of Comparative #2 of Comparative days Example 2 Example 3 Example 2 Example 3 Example 2 Example 3 1 Days N N N N N N 3 Days N S N N N N 5 Days N M N S N N 7 Days N H N H N N N = No precipitate S = Small amount of precipitates M = Moderate amount of precipitates H = High amount of precipitates

[0136] As a result, precipitates were not formed over time regardless of the dilution concentration in #2 of Example 2, but precipitates were formed over time when Comparative Example 3 was diluted to 1:1 or 2:1. The reason for the results was considered to be that the stability of Comparative Example 3 was maintained due to viscosity even in a supersaturated state of DOT, but when Comparative Example 3 was diluted, DOT exceeded the original solubility thereof due to a decrease in viscosity, thereby forming precipitates.

[0137] It can be seen from the above experimental test results that the composition of the present invention has excellent effects in terms of flame retardancy, discoloration resistance, whitening resistance, rot resistance, insect repellence, and inhibition of weight reduction caused by iron corrosion, and thus has superior effects in wood preservation.

[0138] While the present invention has been described with reference to the particular illustrative embodiments, those skilled in the art to which the present invention pertains can understand that the present invention may be embodied in other specific forms without departing from the technical spirit or essential characteristics thereof. Therefore, the embodiments described above shall be construed as being exemplified and not limiting the present invention in any aspect. The scope of the present invention is not defined by the detailed description as set forth above but by the accompanying claims of the invention, and it should also be understood that all changes or modifications derived from the definitions and scopes of the claims and their equivalents fall within the scope of the invention.