JPH11268008A - Flame-retarding composition and flame-retarding treatment process for woody material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a harmless flame-retarding composition free from ammonia smell, not generating formaldehyde and not using a halogenated compound as the composition of generating dioxin at the time of burning and also provide a flame-retarding treatment process for a woody material for carrying out the flame-retarding treatment easily and with good workability by using the flame-retarding composition. SOLUTION: A flame-retarding composition for a woody material is composed of orthophosphoric acid and urea dissolved together in water, or composed of an orthophosphoric acid and urea water solution into which alcohol is added. In a flame-retarding treatment process for the woody material, respective flame- retarding treatment processes are applied on the woody material for coating, and then the woody material is dried, or the woody material is immersed in the flame-retarding compositions, and then the woody material is dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to, for example, wood veneer,
The present invention relates to a flame retardant composition for imparting flame retardancy to particle board, plywood, and the like (these materials are generally referred to as a wood material), and a flame retardant treatment method for a wood material using the flame retardant composition.

[0002]

2. Description of the Related Art First, a general method for flame retarding woody materials will be described. In general, a flame retardant composition used for wood materials is composed of relatively limited types of elements. These elements include Vb group elements such as N, P, and Sb, halogen group VIIb elements, A
Elements such as 1, B, S, and Zr. Incidentally, N itself does not have a flame retardant action, but exhibits a synergistic effect of flame retardation in combination with P. Sb is Br
Used in combination with Compounds containing these elements control a solid-phase reaction (a thermal decomposition reaction process) or an interfacial reaction, and suppress the transfer of oxygen or heat to suppress combustion. Halogen-containing compounds are generally known to control the gas phase reaction to suppress combustion [edited by The Japan Wood Preservation Association,
"Recycling technology and safe disposal technology for preservation waste material" (1994)].

[0003] In order to exhibit the flame-retardant effect, it is known to use a physical action or a chemical action. The former is based on boric acid or borax. Boric acid is thermally decomposed into boron oxide, which covers the combustibles and blocks oxygen and heat. There is also a method of foaming using an amino resin or the like. Amino resins exhibit flame retardancy because products generated during combustion cover the combustibles to block the flame. When foaming by melting, the foam becomes an obstruction to air and flame and hinders combustion. 1
The amount of air required to burn kg wood material is about 4
Since it is relatively large, km ³ , combustion is suppressed if air is cut off by foaming. Aluminum hydroxide exhibits an endothermic effect, and exhibits flame retardancy due to a thermal effect.

[0004] Water, CO ₂ , NH ₃ , SO ₂ , SO _{3 and the} like are nonflammable gases and have a flame retardant effect. Compounds that generate such nonflammable gas include alkali carbonate,
Alkali bicarbonate, ammonium halide, orthophosphate, chloride, sulfamate, sulfate and the like are known. These compounds decompose at temperatures lower than 270 ° C. to produce nonflammable gases [Yoshiyuki Inoue, “Wood Conservation Chemistry” (1969), Uchida Ritsurupo Shinsha].

[0005] Next, as a result of chemical action, halogen-based flame-retarding compositions use a gas produced by vaporization or thermal decomposition of the composition itself as a radical scavenger to stop the radical chain reaction during gas combustion. It is known to exhibit a chemical effect [Forestry Experiment Station, edited by “New Edition Wood Industry Handbook”, 1967, Maruzen Co., Ltd.]. in addition,
It also exhibits a combustion suppression effect by dilution of the halogen-containing gas itself.

Further, the halogen-based flame retardant composition acts on cellulose in a solid phase, and promotes the formation of carbonized residue. In this case, the halogen compound contained in the composition functions as a radical scavenger and suppresses a chain reaction of combustion.
The effect of the halogen to suppress the chain reaction is in the order of Cl <Br <I [Shizuo Kubota, Dyeing Industry, 32 (2), 7
4 (1984); S Kubota, POLYMERIC MATERIALS ENC
YCLOPEDIA, Volume 4 (FG), p.2389, CRC Press
(1996), Yoshiyuki Inoue, "Wood Protection Chemistry" (196)
9) Uchida Lao Tsurupo New Company].

[0007] On the other hand, orthophosphoric acid is known for flame retardancy of cellulose. Orthophosphoric acid is known to act as a dehydration catalyst and react with hydroxyl groups of cellulose to thermally decompose cellulose to carbon and water. In the flame retardant composition containing orthophosphoric acid, orthophosphoric acid is first bonded to the OH group at the 6-position carbon of cellulose by esterification, and then water is eliminated to form C = C. This orthophosphoric acid changes the thermal decomposition mechanism of wood material (cellulose),
Suppresses generation of combustible gas (such as levoglucosan).
In other words, a method of eliminating the reactive side chain free radicals of cellulose from before the onset of a flame cuts off the decomposition route from cellulose to levoglucosan, thereby exhibiting a flame retardant effect. ), 74 (198)
4); S Kubota, POLYMERIC MATERIALS ENCYCLOPEDIA
, Volume 4 (FG), p.2389, CRC Press (199
6), Yoshiyuki Inoue, "Wood Conservation Chemistry" (1969), Uchida Lai Tsurupo Shinsha].

Therefore, in practice, as the flame retardant composition used for woody materials, compounds containing phosphorus and nitrogen are known, similarly to the flame retardant composition for cellulose. For example, a mixture of primary and secondary ammonium phosphates, orthophosphoric acid and a melamine resin (methylolmelamine), and the like. Examples of chlorides used for wood materials include, for example, zinc chloride (a mixture of zinc chloride and sodium dichromate), rubber chloride, and paraffin chloride [Forestry Experiment Station, “Shinban Wood Industry” Handbook ", 1967, Maruzen Co., Ltd.].

That is, as a flame retardant composition for wood materials, a phosphoric acid compound such as ammonium phosphate, dicyandiamide, and the like are known. hand,
By blocking the decomposition pathway of cellulose, dehydration carbonization is promoted and the occurrence of flame is prevented. As a treatment method using such a flame retardant composition, for example, Japanese Patent Application Laid-Open No. 53-20402 discloses Japanese Patent Publication No. 49-4860.
No. 0 discloses a method for improving the flame retardancy of cellulose, which is applied to flame retardancy of woody materials. According to the treatment method disclosed in this publication, a wood material is immersed and dried in an aqueous solution of condensed ammonium phosphate obtained by heating and condensing phosphoric acid and urea, and then heated to a predetermined temperature to cause a reaction. It is designed to impart flame retardancy to the material.

[0010]

When a wood material is subjected to a flame retarding treatment, the wood material that has been subjected to a flame retarding treatment with a boric acid compound has a higher flame retardancy than the one that has been subjected to a flame retarding treatment with a phosphoric acid compound. Is inferior. This is believed to be due to the loss of boric acid by the water vapor generated during carbonization.
In addition, the formation of a film, the formation of a glassy melt, or foaming has a heat insulating effect, and potassium carbonate, cyanide, acetate and the like form a carbonized phase, thereby providing heat insulation. However, these compounds have the disadvantage of producing strong alkali upon thermal decomposition. In addition, halogen (chlorine, bromine)
Has the problem that dioxin is generated during combustion.

On the other hand, chemicals (eg, N-methyloldimethylphosphonopropionamide (Pyrobatex CP of Ciba Geigy) and melamine resin) for fixing the flame retardant composition by reacting it with cellulose are not only used at the time of processing but also at the time of processing. Formaldehyde is also emitted from products, causing indoor air pollution. Further, among the above-mentioned compositions for flame retardation, although the flame retardant effect of the composition itself is recognized, a large amount of the composition is required in view of the characteristics of the woody material, and the flame retardant treatment is extremely large. Many require a lot of time and effort.

The flame retardant composition used in the above-mentioned JP-A-53-20402 requires a heating step in order to condense phosphoric acid and urea to obtain condensed ammonium phosphate. In addition, there is a drawback in that when heated during the flame-retarding treatment, ammonia is generated to give off odor. Furthermore,
Compounds containing phosphorus and nitrogen, such as condensed ammonium phosphate, are particularly effective for cellulose due to their synergistic effect, but in order to properly carry out the condensation reaction, the mixing ratio of phosphoric acid and urea must be a predetermined value. Must be ratio. Further, it is necessary to heat and fix after applying or immersing the flame retardant composition to the wood material, and a large-scale heat treatment device for fixing is required. . Furthermore, in order to synthesize these flame retardant compositions, a large-scale reactor is required, and the reaction requires a long time. Also, among the compositions for flame retardation, some orthophosphate esters are highly toxic such as tris (2,3-dibromopropyl) phosphate.

On the other hand, when a wood material is impregnated with a flame retardant composition using polyethylene glycol or the like as a penetrating agent, the polyethylene glycol does not evaporate and evaporates in the wood material even when air-dried or heat-dried. Because of the stagnant state, there is a problem that the fixing state of the active ingredient is poor, and the active ingredient of the flame retardant composition easily escapes together with the polyethylene glycol by rainwater or the like. Further, when the flame retardant composition containing lactitol as a carrier agent is impregnated into a wood material, there is a problem that the insect repellent effect and the fungicide effect are weakened.

The present invention has been made in view of the above problems, and has no ammonia odor, does not generate formaldehyde, is non-toxic, and does not use a halogen compound which causes dioxin generation during combustion. An object of the present invention is to provide a flame-retardant composition and a method for flame-retarding a woody material that can easily perform a flame-retardant treatment with good workability using the flame-retardant composition.

[0015]

In order to solve the above-mentioned conventional problems, the present inventors have focused on orthophosphoric acid having an excellent flame-retardant effect, and have a simple composition containing orthophosphoric acid as a main component. However, as a result of intensive studies as to whether a flame retardant composition free of the above problems could not be found, the present invention was completed. That is, the present invention relates to a flame retardant composition for woody material obtained by dissolving orthophosphoric acid and urea in water, or a flame retardant composition for woody material obtained by adding alcohol to an aqueous solution of orthophosphoric acid and urea. The gist, further, after applying the respective flame retardant composition to the wood material, drying the wood material, or, after immersing the wood material in the flame retardant composition, the The gist of the present invention is to provide a method for flame retarding a wood material by drying the wood material.

[0016]

Embodiments of the present invention will be described below. The orthophosphoric acid and urea used in the present invention having the above constitution are water-soluble chemicals which are generally available and have no toxicity. Among them, urea swells the woody material, improves the penetration of the flame retardant composition, contributes to dimensional stability, and develops flame retardancy depending on the thickness of the woody material.

The mixing ratio of orthophosphoric acid and urea in the present invention is not particularly limited as long as it is within a practical range. For example, in the case of a composition that expects a chemical reaction (esterification reaction) as in the past, the ratio of phosphorus to nitrogen is specified, whereas the mixing ratio of orthophosphoric acid and urea of the present invention is treated. It can be changed freely according to the properties of the woody material. Since the flame retardation is promoted by the reaction of cellulose and orthophosphoric acid of the woody material, it is considered that a higher mixing ratio of orthophosphoric acid is preferable, but as a result, the mixing weight ratio of orthophosphoric acid and urea is 1%. : 9 to 6:
Treating the wood material between 4 increased flame retardancy. On the other hand, urea itself is known to have no flame-retardant effect. However, when urea itself is present together with orthophosphoric acid, it exhibits a higher flame retardancy than the case of using orthophosphoric acid alone due to a synergistic effect. In the case of using a flame retardant composition containing more urea than orthophosphoric acid: urea = 1: 9, urea may precipitate on the surface of the wood material and impair the sustainability of the flame retardancy.

The weight percentage of orthophosphoric acid and urea relative to the total weight of the aqueous solution is preferably 5% to 80%, more preferably 30% to 60%.
If it is less than 5%, the flame retardant effect may not be provided to the wood material, and if it is more than 80%, the surface of the wood material may be sticky.

When an alcohol is used in the present invention, it is preferable that the alcohol easily evaporates during drying and is relatively inexpensive and easily available. Examples of such a material include ethyl alcohol, methyl alcohol, and isopropyl alcohol. The alcohol is used in an amount of 10 to 60 based on the total weight of the finally obtained flame retardant composition.
It is preferred to add by weight. Thereby, the stickiness after the flame retarding treatment is eliminated, and the permeability of the composition in the thickness direction of the material is improved. Therefore, it is suitable for a case where a thick wood material is subjected to flame retarding treatment. If the amount of the alcohol is less than 10% by weight, the penetrating power to the wood material is reduced, and the flame retardancy is reduced accordingly. On the other hand, when the amount of alcohol added exceeds 60% by weight, it is easy to penetrate deep into the woody material, but the flame retardancy is also lowered because the absolute concentration of the flame retardant composition at the permeated site is too low.

In preparing the flame retardant composition containing alcohol, first, orthophosphoric acid and urea are dissolved in water to form an aqueous solution. In this way, there is no problem even if alcohol is subsequently added to the aqueous solution.
On the other hand, when orthophosphoric acid and urea are added to a mixture of water and alcohol in advance, a cloudy liquid is obtained. When such a cloudy liquid is applied to the surface of a wooden material, the effective components (orthophosphoric acid and urea) are not uniform on the surface of the wooden material, so that the flame retardant effect is reduced.

Since the aqueous solution or alcohol aqueous solution of the composition for flame retardation constituted as described above is hydrophilic and has low viscosity, it has good permeability even to a wood material having a high water content.
This seems to be due to the swelling action and moderate moisturizing action of urea. In addition, a preservative such as boric acid or borax may be added to the flame retardant composition according to the present invention.

When the wood material is subjected to the flame retarding treatment by the method of the present invention, it is necessary to fix the flame retardant composition to the wood material by a predetermined means. That is, the flame-retarding composition is applied to the surface of the wood material, or the entire material is immersed for about 1 to 48 hours and then dried, and can be fixed near the material surface without heat treatment.
Flame retardancy can be imparted to wood materials.

In drying the woody material after the coating treatment or the immersion treatment, natural drying such as air drying may be performed.
Alternatively, forced drying by heating may be used. An appropriate mode of drying may be adopted according to the size and thickness of the woody material or the surrounding environmental conditions.

The wood material impregnated with the flame retardant composition of the present invention by a predetermined means has excellent antiseptic and termite resistance. This is thought to be due to the fact that the digestive enzyme of the composition component of the present invention does not exist in the intestine of the ant that causes harm and the ant cannot be nourished, thereby leading to the development of the decay-resistant effect and the corrosion-resistant effect. .

The woody material treated with the flame retardant composition of the present invention includes not only wood veneer but also fiberboard, particleboard, plywood and the like. Examples of tree species used for woody materials include:
Examples include conifers such as cedar, pine, cypress, toga, and rice pine, and broadleaf trees such as buna, oak, oak, Makamba, shiino tree, lauan, and apiton.

[0026]

EXAMPLES The present invention will be described more specifically with reference to examples. Example 1 A mixture having a weight ratio of orthophosphoric acid and urea of "9: 1" was prepared, and a 50% by weight aqueous solution was prepared from this mixture to prepare a composition for flame retardancy. This flame retardant composition was prepared as follows: length 300 mm × width 120 mm × thickness 1 m
The test specimen (m) (applied to a wood veneer (tree type: Yonematsu)) was air-dried and fixed. The test is J
The test was carried out in accordance with the fiber burning test method (micro burner method (for thin specimens)) according to IS-L-1091.

In the above-described combustion test method, a flame is applied to a test body arranged at an angle of 45 degrees to measure the degree of spread of combustion and the like. The extent of combustion spread is evaluated based on the area of the carbonized portion of the test body (carbonized area) and the maximum length of the carbonized portion (carbonized distance). In addition, since the test piece is placed at an angle, the carbonized part tends to be naturally elliptical, and the place where the flame hits is not necessarily at the center of the carbonized part because the woody material has the directionality of the fiber. Since there is no carbonization, the flame retardancy was determined from both the carbonized area and the carbonized length. As shown in Table 1, the test results in Example 1 show that the carbonized area was 59.3 cm ² and the carbonized length was 12.0.
cm. In this case, the surface of the veneer had a sticky feeling. Table 1 also shows the test results of Examples 2 to 5 below.

[0028]

[Table 1]

Example 2 A test was carried out in the same manner as in Example 1 except that a composition for flame retardation was prepared from a mixture of orthophosphoric acid and urea at a weight ratio of "7: 3". The result is
The carbonized area was 55.0 cm ² and the carbonized length was 8.8 cm.
This example also had a sticky feeling.

Example 3 A test was carried out in the same manner as in Example 1 except that a flame retardant composition was prepared from a mixture of orthophosphoric acid and urea at a weight ratio of "5: 5". The result is
The carbonized area was 32.1 cm ² and the carbonized length was 7.0 cm.

Example 4 A test was conducted in the same manner as in Example 1 except that a composition for flame retardation was prepared from a mixture of orthophosphoric acid and urea at a weight ratio of “3: 7”. The result is
The carbonization area was 29.5 cm ² and the carbonization length was 7.0 cm.

Example 5 A test was conducted in the same manner as in Example 1 except that a composition for flame retardation was prepared from a mixture of orthophosphoric acid and urea at a weight ratio of "1: 9". The result is
The carbonization area was 35.9 cm ² and the carbonization length was 9.5 cm.
In Examples 3 to 5 described above, no stickiness was felt on the surface of the wooden material.

Comparative Example 1 JP-A-53-204 described above
A flame-retardant composition was prepared with the same formulation as in Example 1 in the flame-retardant treatment method disclosed in JP-A-02-02. That is, a mixture of orthophosphoric acid and urea in a weight ratio of "1: 3" is heated to form a condensate, and water is added to the condensate to form a condensate.
An aqueous solution having a concentration of 0% by weight was prepared, and 5% by weight of urea was added to the aqueous solution to obtain a flame retardant composition. The flame retardant composition was added with a length of 300 mm and a width of 12 mm.
A wood veneer (tree type: Yonematsu) having a size of 0 mm x 1 mm was “immersed” and dried to be tested. The test is JIS-L
The test was carried out according to the fiber combustion test method (micro burner method) according to -1091. As shown in Table 2, this test result had a carbonized area of 61.9 cm ² and a carbonized length of 14.5 cm. Table 2 also shows the results of Comparative Example 2 below.

[0034]

[Table 2]

Comparative Example 2 A flame retardant composition prepared according to the same formulation as in Comparative Example 1 was immersed in the same test specimen as in Comparative Example 1, air-dried, and further dried based on Example 2 of the publication.
The test piece was fixed on the test piece by heat treatment at 0 ° C. for 6 minutes. The specimen thus prepared was subjected to a fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonized area was 71.8 cm ² and the carbonized length was 15.0 cm. Further, in both Comparative Examples 1 and 2, stickiness was produced on the surface of the wooden material.

As described above, in the flame retardant compositions according to Examples 1 to 5, water evaporates by air drying, and orthophosphoric acid and urea are fixed on the surface and deep layer of the veneer veneer. Incidentally, orthophosphoric acid and urea each have a flame-retardant effect on wood materials, but because they are used in combination, they exhibit synergistic effects with each other. Therefore, the compositions for flame retardancy of Examples 1 to 5 show a remarkable flame retardant effect as compared with Comparative Examples 1 and 2, despite the fact that Comparative Examples 1 and 2 are "immersed". Further, the compounding ratio in a certain range (Examples 3 to 5)
If so, the stickiness will disappear.

Example 6 A mixture having a weight ratio of orthophosphoric acid and urea of "3: 7" was prepared.
A weight percent aqueous solution was prepared as a flame retardant composition. A immersion tank filled with the composition for flame retardation is 300 mm long.
After a wood veneer (tree type: Yonematsu) having a width of 120 mm and a thickness of 1 mm was “immersed”, it was taken out and air-dried, and subjected to a test. The test was performed in accordance with the fiber combustion test method (micro burner method) according to JIS-L-1091. As shown in Table 3, the test results showed that the carbonized area was 16.0 cm ² ,
The carbonization length was 5.0 cm. When treated by "immersion" as in Example 6, compared with the case where the flame retardant composition prepared under the same conditions was treated by "application" (Example 4), penetration into the inside of the material spreads, It can be seen that the flammability has been greatly improved.

[0038]

[Table 3]

Example 7 A mixture having a weight ratio of orthophosphoric acid and urea of "3: 7" was prepared.
An aqueous solution having a concentration of% by weight was prepared to obtain a flame retardant composition.
This flame retardant composition was prepared as follows: length 300 mm × width 120 mm
X A 1 mm thick medium-density fiberboard (hereinafter abbreviated as MDF) was applied and then air-dried. The test was performed in accordance with the fiber combustion test method (micro burner method) according to JIS-L-1091. As shown in Table 4, the test results were as follows: carbonized area 34.9 cm ² , carbonized length 7.
5 cm. Table 4 also shows Examples 8 to 10 below.

[0040]

[Table 4]

Example 8 A flame-retardant composition prepared according to the same formulation as in Example 7 was prepared by mixing a composition having a length of 300 mm × a width of 120 mm ×
What was applied to a 1 mm thick cedar board was used for the test. The test was performed in accordance with the fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonization area was 44.1 cm ² and the carbonization length was 8.5 cm.

Example 9 A mixture having a weight ratio of orthophosphoric acid and urea of "5: 5" was prepared, and an aqueous solution having a concentration of 50% by weight was prepared as a flame retardant composition. This flame retardant composition was prepared as follows: length 300 mm × width 120 mm × thickness 2
The sample was applied to an MDF having a thickness of 1 mm and air-dried, and then subjected to a test. The test was performed in accordance with the fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonization area was 27.1 cm ² and the carbonization length was 6.0 cm.

Example 10 A flame-retardant composition prepared according to the same formulation as in Example 9 was prepared using a composition having a length of 300 mm and a width of 120 mm.
X A 2 mm-thick cedar board was applied and then air-dried. The test was performed in accordance with the fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonization area was 29.3 cm ² , and the carbonization length was 6.5 cm.
Met.

As in each of Examples 7 to 10 described above, even when MDF or cedar was used as the woody material, Comparative Examples 1 and 2 were used.
2 shows that the composition is excellent in flame retardancy and stickiness, and that the composition for flame retardation of each Example is suitable regardless of the type of wood material.

Example 11 A mixture having a weight ratio of orthophosphoric acid and urea of "5: 5" was prepared.
An aqueous solution having a concentration of 0% by weight was prepared, and "30% by weight" of "ethyl alcohol" was added to the total weight of the final composition to obtain a flame retardant composition. This flame retardant composition was applied to an MDF having a length of 300 mm, a width of 120 mm and a thickness of 2 mm, and then air-dried. The test is JIS-
The test was carried out according to the fiber combustion test method according to L-1091 (Meckelburner method (for thick specimens)). As a result of the test, as shown in Table 5, the carbonized area was 66.4 cm ² and the carbonized length was 11.5 cm. In addition, the following Examples 12 to 1
Table 5 also shows Table 5.

[0046]

[Table 5]

Example 12 A flame-retardant composition prepared according to the same formulation as in Example 11 was prepared using a composition having a length of 300 mm and a width of 120 m.
After coating on an oriented strand board (hereinafter abbreviated as OSB) of mx 2 mm in thickness and air-dried, it was subjected to a test. The test was performed in accordance with the fiber combustion test method (Meckelburner method) according to JIS-L-1091. As a result, the carbonized area was 67.6 cm ² and the carbonized length was 1.
It was 2.5 cm.

Example 13 A flame-retardant composition prepared according to the same formulation as in Example 11 was prepared using a composition having a length of 300 mm and a width of 120 m.
After applying to a cedar board of mx 2 mm in thickness and air-dried, it was subjected to the test. The test was performed in accordance with the fiber combustion test method (Meckelburner method) according to JIS-L-1091. As a result, the carbonized area was 87.9 cm ² and the carbonized length was 1.
It was 2.5 cm.

Example 14 A mixture having a weight ratio of orthophosphoric acid and urea of "5: 5" was prepared.
An aqueous solution having a concentration of 0% by weight was prepared, and “50% by weight” of ethyl alcohol was added to the total weight of the final composition to obtain a flame retardant composition. This flame retardant composition was used for a length 3
The sample was applied to an OSB having a size of 00 mm x a width of 120 mm x a thickness of 2 mm and then air-dried. The test is JIS-L
The test was carried out according to the fiber combustion test method according to -1091 (Meckelburner method). As a result, the carbonized area was 45.8.
cm ² and a carbonization length of 11.5 cm.

Example 15 A flame-retardant composition prepared according to the same formulation as in Example 14 was prepared using a composition having a length of 300 mm and a width of 120 m.
What applied to the cedar board of mx 2 mm in thickness was used for the test. The test was performed in accordance with the fiber combustion test method (Meckelburner method) according to JIS-L-1091. As a result, the carbonized area was 44.6 cm ² and the carbonized length was 10.5 cm.

As described above, Embodiments 11 to 15
Uses thick (2 mm) woody material in anticipation of the permeability improvement effect of the addition of ethyl alcohol.
Reasonable results have been obtained in both flame retardancy and stickiness. In this case, it is better to add ethyl alcohol in a large amount (50% by weight, Examples 14 and 15).
High flame retardancy was exhibited as expected. There was no difference in the stickiness in the table, but the feeling was better as the amount of alcohol added was larger.

[0052]

As described above, the flame-retardant composition according to the present invention is a simple composition obtained by dissolving orthophosphoric acid and urea in water, so that the production of the composition is not significant. No equipment is required and a long reaction time is not required. Further, since there is no need to cause a condensation reaction between orthophosphoric acid and urea, the mixing ratio of these components is arbitrary. By appropriately adjusting the compounding ratio, the degree of flame retardancy and the presence or absence of stickiness can be adjusted. In addition, "the phosphoric acid and urea are heated to obtain a condensate, and further, an aqueous solution of the condensate is obtained to obtain a flame retardant composition, a wood material is immersed in the composition, dried, and then heat-fixed." Compared to the prior art, despite having a simple composition as described above, orthophosphoric acid and urea exhibit a synergistic effect and exhibit a remarkable flame retardant effect. Then, since orthophosphoric acid and urea are fixed by evaporating water in the drying step, a fixing heating step for flame retarding treatment as in the related art is not required.

When an alcohol is added, the flame retardant composition tends to penetrate deep into the woody material. Since the alcohol used here has a low boiling point and easily evaporates, even in the case of natural drying such as air-drying, the alcohol not only in the vicinity of the material surface but also in the deep layer evaporates and promotes the fixation of orthophosphoric acid and urea. Therefore, the use of alcohol is particularly suitable for the case where a thick woody material is subjected to flame retarding treatment. Further, the stickiness of the surface of the woody material after the flame retarding treatment is further reduced.

According to the flame-retardant treatment method of the present invention, the flame-retardant composition is fixed only by applying the flame-retardant composition to the surface of the wooden material and drying it. Therefore, a heat treatment for fixing is not required, and the flame retarding treatment can be easily performed. Furthermore, since the flame retardant composition is rich in fluidity, when the wood material is "immersed", the flame retardant composition permeates a large amount into the wood material, and the flame retardancy is further improved. Hard to run off by rainwater.

That is, the wood material treated by the flame retardant composition or the flame retardant treatment method according to the present invention exhibits extremely high flame retardancy, good appearance, and excellent durability. In addition, even if the wood material has a high water content, it tends to be flame-retardant, and the surface does not have unnatural coloring and does not lose its natural wood texture. Since it does not contain chlorine or bromine, there is no generation of dioxin or bromodioxin during combustion, and it is harmless because ammonia and formaldehyde are not generated during processing as well as in products. Furthermore, it is excellent in the adhesiveness of the paint, and has an antiseptic effect and an anti-termite effect.

Claims (4)

[Claims] 1. A composition for flame retarding woody materials, wherein orthophosphoric acid and urea are dissolved in water. 2. A composition for flame retarding woody materials, wherein orthophosphoric acid and urea are dissolved in water and alcohol is added to the aqueous solution. 3. A method for flame retarding a wood material, comprising applying the flame retardant composition according to claim 1 or 2 to a wood material, and drying the wood material. 4. A method for flame retarding a wood material, comprising: immersing the wood material in the flame retardant composition according to claim 1 or 2, and drying the wood material.