JP3418821B2 - Composition for flame retarding woody materials and flame retarding treatment method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wood veneer,
The present invention relates to a flame-retardant composition for imparting flame retardancy to particle boards, plywood and the like (collectively referred to as wood-based materials), and a flame-retardant treatment method for wood-based materials using the flame-retardant composition.

[0002]

2. Description of the Related Art First, a general flame retardant treatment method for wood materials will be outlined. Flame-retardant compositions that are generally used for wood materials are composed of relatively limited types of elements. These elements are Vb group elements such as N, P, Sb, halogen VIIb group elements, A
It is a group of elements such as l, B, S, and Zr. Incidentally, N has no flame retardant effect by itself, but exhibits a synergistic effect of flame retardancy when combined with P. Also, Sb is Br
Used in combination with. The compound containing these elements controls solid-phase reaction (thermal decomposition reaction process) and interfacial reaction, interrupts transfer of oxygen and heat, and suppresses combustion. Compounds containing halogen are generally known to control the gas phase reaction to suppress combustion [edited by the Japan Wood Preservation Association,
"Technology for recycling waste disposal materials and safe disposal technology" (1994)].

In order to exhibit the flameproof effect, it is known that it is based on a physical action and a chemical action. The former is due to boric acid and borax. Boric acid is thermally decomposed into boron oxide, and this boron oxide covers combustible materials to block oxygen and heat. There is also a method of foaming using an amino resin or the like. The amino resin exhibits flame retardancy because the product produced during combustion covers the combustible material to block the flame. When foamed by melting, the foam becomes an obstacle to air and flames and prevents combustion. 1
The amount of air required to burn kg of wood material is about 4
Since it is relatively large at km ³ , combustion is suppressed if air is cut off by foaming. Then, aluminum hydroxide exhibits an endothermic effect, and flame retardancy is exhibited by a thermal action.

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

Next, as a chemical action, in the halogen-based flame retardant composition, the gas generated by vaporization or thermal decomposition of the composition itself serves as a radical scavenger to stop the radical chain reaction during gas combustion. It is known to exhibit a chemical action [Forestry Experiment Station, "New Edition Wood Industry Handbook", 1967, Maruzen Co., Ltd.]. in addition,
It also exhibits a combustion suppressing effect by diluting the halogen-containing gas itself.

Further, the halogen-based flame-retardant composition acts on cellulose even in the solid phase to promote the formation of carbonization residue. In this case, the halogen compound contained in the composition acts as a radical scavenger and suppresses a chain reaction of combustion.
The chain reaction suppressing effect of halogen is said to be 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 Conservation Chemistry" (196)
9) Uchida Old Tsurupo Shinsha].

On the other hand, orthophosphoric acid is known for the flame retardation of cellulose. Orthophosphoric acid acts as a dehydration catalyst and is known to react with hydroxyl groups of cellulose to thermally decompose cellulose into carbon and water. In the flame retardant composition containing orthophosphoric acid, first, orthophosphoric acid is bonded to the OH group of 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 the production of combustible gas (levoglucosan, etc.).
That is, the method of eliminating the highly reactive cellulose side-chain free radicals before inflammation causes the decomposition route of cellulose to levoglucosan to be cut off, thereby exhibiting a flame-retardant effect [Shizuo Kubota, Dyeing Industry, 32 (2 ), 74 (198
4); S Kubota, POLYMERIC MATERIALS ENCYCLOPEDIA
, Volume 4 (FG), p.2389, CRC Press (199
6), Yoshiyuki Inoue, "Wood Conservation Chemistry" (1969), Uchida Lao Tsurupo Shinsha].

Therefore, in practice, as the flame-retardant composition used for wood materials, a compound containing phosphorus or nitrogen is known as in the case of the flame-retardant composition of cellulose. For example, a mixture of primary and secondary ammonium phosphates, orthophosphoric acid and a melamine resin (methylolmelamine), and the like. Chromated zinc chloride (a mixture of zinc chloride and sodium dichromate), chlorinated rubber, chlorinated paraffin, etc. are known as chlorides used for wood materials [Forestry Research Institute, "New Edition Wood Industry"]. Handbook ", 1967, Maruzen Co., Ltd.].

That is, phosphoric acid compounds such as ammonium phosphate and dicyandiamide are known as flame retardant compositions for wood materials, and become orthophosphoric acid esters by heating during flame retarding treatment or during combustion. hand,
By blocking the cellulose decomposition pathway, dehydration and carbonization is promoted to prevent the occurrence of flame. As a treatment method using such a flame retardant composition, for example, JP-A-53-20402 discloses Japanese Patent Publication No. 49-4860.
The cellulose flame retardant treatment method disclosed in Japanese Patent No. 0 is disclosed and applied to the flame retardation of wood materials. According to the treatment method disclosed in this publication, the woody material is immersed in an aqueous solution of condensed ammonium phosphate obtained by heating and condensing phosphoric acid and urea, and the woody material is dried and then heated to a predetermined temperature to cause a reaction. It is designed to impart flame retardancy to materials.

[0010]

By the way, when the wood material is flame-retarded, the wood material treated with the boric acid compound is more flame-retardant than that treated with the phosphoric acid compound. Is inferior. It is considered that this is because boric acid is lost due to steam generated during carbonization.
Further, there is an adiabatic action in the formation of a film, the formation of a glassy melt, foaming, etc., and potassium carbonate, cyanide, acetate, etc. form a carbonized phase, which provides heat insulation. However, these compounds have a drawback that they generate a strong alkali upon thermal decomposition. In addition, halogen (chlorine, bromine)
The flame-retardant composition containing is disadvantageous in that it produces dioxin during combustion.

On the other hand, agents for reacting the flame-retardant composition with cellulose to fix the composition (for example, N-methyloldimethylphosphonopropionamide (Pyrovatex CP of Ciba-Geigy Co.) and melamine resin) are used not only during processing. Formaldehyde is also emitted from products, causing indoor air pollution. Further, among the above-mentioned flame retardant composition, 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 wood-based material, and a great deal of flame retardant treatment is required. Many of them take a lot of time and effort.

Further, 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 ammonia is generated by heating during the flame-retardant treatment to give offensive odor. Furthermore,
A compound containing phosphorus and nitrogen, such as condensed ammonium phosphate, is particularly effective for cellulose due to their synergistic effect, but in order to properly perform the condensation reaction, the compounding ratio of phosphoric acid and urea should be a predetermined value. Must be in proportion. In addition, since it is necessary to heat and fix the wood material after applying or immersing the flame retardant composition to the wood material, which requires a large-scale heat treatment device for fixing, there is a limit to the size of the wood material that can be heat-treated. . Furthermore, in order to synthesize these flame retardant compositions, a large-scale reaction device is required, and the reaction also takes a long time. Among the flame retardant compositions, some orthophosphoric acid esters are highly toxic, such as tris (2,3-dibromopropyl) phosphate.

On the other hand, when a wood-based material is impregnated with a flame-retardant composition using polyethylene glycol or the like as a penetrant, polyethylene glycol does not evaporate in the wood-based material even when air-dried or heat-dried. Since it stays, the fixing state of the active ingredient is poor, and there is a problem that the active ingredient of the flame retardant composition is easily washed out together with polyethylene glycol due to rainwater or the like. Further, when a wood-based material is impregnated with a flame-retardant composition containing lactitol as a carrier agent, there is a problem that the insect-proof effect and the mildew-proof effect are weakened.

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

[0015]

In order to solve the above-mentioned conventional problems, the present inventor has focused on orthophosphoric acid having an excellent flame retardant effect and has a simple composition containing this as a main component. However, as a result of diligent research into whether or not a composition for flame retarding without the above-mentioned problems can be found, the present invention has been completed. That is, the present invention, orthophosphoric acid and urea is dissolved in water, the flame retardant composition of the woody material formed by adding an alcohol and spirit in the aqueous solution, further, the respective flame retarded compositions Is applied to a wood material, then the wood material is dried, or the wood material is immersed in a flame-retardant composition, and then the wood material is dried. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION 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 a wood-based material to improve the penetration of the flame-retardant composition, contributes to dimensional stability, and exhibits flame-retardant properties depending on the thickness of the wood-based 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 and nitrogen is specified, whereas the mixing ratio of orthophosphoric acid and urea of the present invention is treated. It can be freely changed according to the properties of the wood material. It should be noted that, since the flame retardancy proceeds due to the reaction of the wood material cellulose and orthophosphoric acid, it is considered that it is preferable to add a large proportion of orthophosphoric acid, but as a result, the mixture weight ratio of orthophosphoric acid and urea is 1 : 9 to 6:
The flame retardancy was increased by treating the wood-based material between 4 times. On the other hand, urea itself is known to have no flame retardant effect, but when it coexists with orthophosphoric acid, it shows higher flame retardancy than the case of using orthophosphoric acid alone due to a synergistic effect. When a flame retardant composition containing a larger amount of urea than orthophosphoric acid: urea = 1: 9 is used, urea may be deposited on the surface of the wood material and impair the sustainability of 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 5% or less, the wood material may not have a flame retardant effect, and if it is 80% or more, the surface of the wood material may be sticky.

The use have luer alcohol in the present invention are suitable easy ones available transpiration easy relatively inexpensive when dry. Examples of such substances include ethyl alcohol, methyl alcohol, isopropyl alcohol and the like. Such alcohol is preferably added in an amount of 10 to 60% by weight based on the total weight of the finally obtained flame retardant composition. This eliminates the sticky feeling after the flame-retardant treatment and improves the composition permeability in the material thickness direction. Therefore, it is suitable for flame-retarding a thick wood material. If the amount of alcohol added is less than 10% by weight, the penetrating power into the wood-based material will be small, and the flame retardancy will be reduced accordingly. On the other hand, when the amount of alcohol added exceeds 60% by weight, the wood material easily penetrates deeply, but the absolute concentration of the flame-retardant composition at the permeation site is too dilute, and the flame retardancy also decreases.

When preparing the flame retardant composition containing alcohol, first, orthophosphoric acid and urea are dissolved in water to form an aqueous solution. By doing so, there is no problem even if alcohol is added to the aqueous solution thereafter.
On the other hand, when orthophosphoric acid and urea are added to a mixture of water and alcohol in advance, it becomes a cloudy liquid. When such a cloudy liquid is applied to the surface of the wood material, the active ingredients (orthophosphoric acid and urea) are not uniform on the surface of the wood material, so the flame retardant effect is reduced.

The aqueous solution or alcoholic solution of the flame retardant composition having the above-described structure is hydrophilic and has a low viscosity, and therefore has good permeability even to a wood material having a high water content.
This is considered to be due to the swelling action and the proper moisturizing action possessed by urea. An antiseptic agent such as boric acid or borax may be added to the flame retardant composition according to the present invention.

In flame-retarding the wood material 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, it is possible to fix the composition to the vicinity of the surface of the wood material without heat treatment by simply applying the flame-retardant composition to the wood material, or immersing the whole material for about 1 to 48 hours and then drying.
Flame retardancy can be imparted to wood materials.

When drying the wood-based material after the coating treatment or the dipping treatment, natural drying such as air drying,
Alternatively, forced drying by heating may be used. As the drying mode, an appropriate mode may be adopted according to the size and thickness of the wood material or the ambient environment conditions.

The wood material impregnated with the flame retardant composition according to the present invention by a predetermined means has excellent antiseptic property and ant-preventive property. This is because the digestive enzyme of the composition component of the present invention does not exist in the intestine of the ant which causes corrosion, and the ant cannot feed the ant, which is considered to lead to the expression of the decay-resistant effect and the corrosion-resistant effect. .

The wood materials treated with the flame retardant composition of the present invention include not only wood veneer but also fiberboard, particle board, plywood and the like. Examples of tree species used for wood materials include
Examples include conifers such as cedar, pine, cypress, toga, and pine, and hardwoods such as beech, oak, oak, citrus, shiino tree, rawan, and apiton.

[0026]

EXAMPLES Next, the present invention will be described more specifically by way of examples. [Example 1] A mixture having a weight ratio of orthophosphoric acid and urea of "9: 1" was prepared, and an aqueous solution having a concentration of 50% by weight was prepared from the mixture to obtain a flame retardant composition. This flame-retardant composition has a length of 300 mm, a width of 120 mm and a thickness of 1 m.
The test piece of m (wood veneer (tree species: Yonematsu)) was "coated", air-dried and fixed, and then used for the test. The test is J
The test was performed according to the fiber combustion test method (microburner method (for thin test body)) according to IS-L-1091.

The above-mentioned combustion test method is one in which a flame is applied to a test body arranged at an angle of 45 degrees to measure the extent of combustion and other factors. The extent of combustion is evaluated by the area of the carbonized portion of the test body (carbonized area) or the maximum length of the carbonized portion (carbonized distance). In addition, since the test piece is placed at an angle, the carbonized portion tends to be oval naturally, and because the wood-based material has fiber directionality, the location of the flame is not always at the center of the carbonized portion. Therefore, it was decided to judge the flame retardancy from both the carbonized area and the carbonized length. As shown in Table 1, the test results in Example 1 are as follows: carbonization area 59.3 cm ² , carbonization length 12.0.
It was cm. In this case, the surface of the wood veneer had a sticky feeling. The test results of Examples 2 to 5 below are also shown in Table 1.

[0028]

[Table 1]

Example 2 A test was conducted in the same manner as in Example 1 except that the flame retardant composition was prepared from a mixture of orthophosphoric acid and urea in a weight ratio of “7: 3”. The result is
The carbonization area was 55.0 cm ² and the carbonization length was 8.8 cm.
There was a sticky feeling in this example as well.

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

Comparative Example 1 Japanese Patent Laid-Open No. 53-204
A flame-retardant composition was prepared with the same formulation as in Example 1 in the flame-retardant treatment method disclosed in JP-A No. 02-202. That is, a mixture of orthophosphoric acid and urea in a weight ratio of "1 to 3" is heated to produce a condensate, and water is added to the condensate to obtain 4
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 prepare a flame retardant composition. This flame retardant composition has a length of 300 mm and a width of 12
A wood veneer (tree type: Yonematsu) having a thickness of 0 mm and a thickness of 1 mm was “immersed” and dried to be tested. The test is JIS-L
It was carried out according to the fiber combustion test method (micro burner method) according to -1091. As shown in Table 2, the test results were a carbonization area of 61.9 cm ² and a carbonization length of 14.5 cm. The results of Comparative Example 2 below are also shown in Table 2.

[0034]

[Table 2]

Comparative Example 2 A flame-retardant composition prepared by the same formulation as in Comparative Example 1 was dipped in the same test body as in Comparative Example 1 and then air-dried.
The test piece was fixed by heat treatment at 0 ° C. for 6 minutes. The test body thus prepared was subjected to the 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 Comparative Examples 1 and 2, a sticky feeling was generated on the surface of the wooden material.

As described above, in the flame retardant compositions according to each of Examples 1 to 5, water was evaporated by air drying, and orthophosphoric acid and urea were fixed on the surface of the wood veneer and the deep layer. Incidentally, orthophosphoric acid and urea each have a flame-retardant effect on wood materials, but since they are used together, they exert a synergistic effect on each other. Therefore, the flame-retardant compositions of Examples 1 to 5 exhibit exceptional flame-retardant effects as compared with Comparative Examples 1 and 2, even though the Comparative Examples 1 and 2 are subjected to the "immersion" treatment. In addition, a compounding ratio within a certain range (Examples 3 to 5)
If so, the sticky feeling disappears.

Example 6 A mixture having a weight ratio of orthophosphoric acid and urea of "3: 7" was prepared, and 50% of the mixture was prepared.
A wt% aqueous solution was prepared to obtain a flame retardant composition. In a dipping tank filled with this flame retardant composition, a length of 300 mm ×
A wood veneer having a width of 120 mm and a thickness of 1 mm (tree species: Yonematsu) was “immersed”, taken out, and air-dried to be subjected to the test. The test was performed according to the fiber combustion test method (micro burner method) according to JIS-L-1091. As shown in Table 3, this test result shows that the carbonized area was 16.0 cm ² ,
The carbonization length was 5.0 cm. When treated by "immersion" as in this Example 6, compared with the case where the flame-retardant composition prepared under the same conditions was treated by "application" (Example 4), permeation into the interior of the material was spread and it was difficult. It can be seen that the flammability is greatly improved.

[0038]

[Table 3]

Example 7 A mixture having a weight ratio of orthophosphoric acid and urea of "3: 7" was prepared, and 30% of this mixture was used.
An aqueous solution having a concentration of wt% was prepared to obtain a flame retardant composition.
This flame-retardant composition has a length of 300 mm and a width of 120 mm.
× A medium-density fiberboard (hereinafter, abbreviated as MDF) having a thickness of 1 mm was applied and then air-dried to be subjected to the test. The test was performed according to the fiber combustion test method (micro burner method) according to JIS-L-1091. As shown in Table 4, this test result shows that the carbonization area was 34.9 cm ² and the carbonization length was 7.
It was 5 cm. Table 4 also shows Examples 8 to 10 below.

[0040]

[Table 4]

Example 8 A flame-retardant composition prepared by the same formulation as in Example 7 was used, and was 300 mm in length × 120 mm in width ×
The test piece was applied to a cedar plate having a thickness of 1 mm. The test was performed according to the fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonized area was 44.1 cm ² and the carbonized 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 to obtain a flame retardant composition. This flame-retardant composition has a length of 300 mm, a width of 120 mm and a thickness of 2
What was applied to MDF mm mm and air dried was used for the test. The test was performed according to 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 by the same formulation as in Example 9 was used, and the length was 300 mm and the width was 120 mm.
C. A test piece was applied to a cedar plate having a thickness of 2 mm and air-dried. The test was performed according to the fiber combustion test method (micro burner method) according to JIS-L-1091. As a result, the carbonized area was 29.3 cm ² , the carbonized length was 6.5 cm.
Met.

Even when MDF or cedar is used as the wood material as in each of Examples 7 to 10 described above, Comparative Example 1,
It is found that the flame retardancy and stickiness are superior to those of No. 2, and the flame retardant composition 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, and 3 parts were prepared from this mixture.
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, which was then air-dried and subjected to a test. The test is JIS-
The test was performed according to the fiber combustion test method (Meckel burner method (for thick test body)) according to L-1091. As shown in Table 5, the test results were a carbonized area of 66.4 cm ² and a carbonized length of 11.5 cm. In addition, the following Examples 12 to 1
5 is also shown in Table 5.

[0046]

[Table 5]

[Example 12] A flame-retardant composition prepared by the same formulation as in Example 11 was used.
An oriented strand board (hereinafter, abbreviated as OSB) having a size of m × 2 mm and applied with air and then dried was used for the test. The test was performed according to the fiber combustion test method (Meckel burner method) according to JIS-L-1091. As a result, the carbonization area was 67.6 cm ² , the carbonization length was 1
It was 2.5 cm.

Example 13 A flame-retardant composition prepared by the same formulation as in Example 11 was used to prepare a composition having a length of 300 mm and a width of 120 m.
After being applied to a cedar plate having a size of m × 2 mm and dried in air, it was used for the test. The test was performed according to the fiber combustion test method (Meckel burner method) according to JIS-L-1091. As a result, the carbonization area was 87.9 cm ² , the carbonization length was 1.
It was 2.5 cm.

Example 14 A mixture in which the weight ratio of orthophosphoric acid and urea was “5: 5” was prepared, and 5% was obtained from this mixture.
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 has a length of 3
An OSB having a size of 00 mm × width 120 mm × thickness 2 mm was air-dried and then subjected to a test. The test is JIS-L
It was carried out according to the fiber combustion test method (Meckel burner method) according to -1091. The result is a carbonized area of 45.8.
It was cm ² , and the carbonization length was 11.5 cm.

Example 15 A flame-retardant composition prepared by the same formulation as in Example 14 was used, and the length was 300 mm and the width was 120 m.
What was applied to a cedar plate of m × thickness 2 mm was used for the test. The test was performed according to the fiber combustion test method (Meckel burner method) according to JIS-L-1091. As a result, the carbonization area was 44.6 cm ² and the carbonization length was 10.5 cm.

As described above, Examples 11 to 15
So, in anticipation of the penetrating effect of the addition of ethyl alcohol, a thick (2 mm) wood material is used.
Correspondingly good results have been obtained with respect to 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).
As expected, it showed high flame retardancy. In addition, the sticky feeling did not show any difference in the table, but the feel was better as the amount of alcohol added was larger.

[0052]

As described above, according to the present invention, the flame retardant composition according to the present invention, orthophosphoric acid and urea because it is easy disjoint composition dissolved in water, large-scale equipment to the composition prepared It does not require a long reaction time. Further, since it is not necessary to cause the condensation reaction of orthophosphoric acid and urea, the compounding ratio of these may be arbitrary. By appropriately adjusting the blending ratio of these, it is possible to adjust the degree of flame retardancy and the presence or absence of stickiness. In addition, "phosphoric acid and urea are heated to obtain a condensate, and an aqueous solution of the condensate is further obtained to form a flame retardant composition, and a wood material is dipped in this to be dried and then heat-fixed." Despite the simple composition as described above, orthophosphoric acid and urea exert a synergistic effect and exhibit a remarkable flame retarding effect, as compared with the prior art.
Further, since the orthophosphoric acid and the urea are fixed by evaporating the water in the drying step, the fixing heating step for the flame retardant treatment unlike the prior art is not required.

Further, since the alcohol is added , the flame retardant composition easily penetrates into the deep portion of the wood material.
Since the alcohol used here has a low boiling point and easily evaporates, even in 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 fixing of orthophosphoric acid and urea. Therefore, the use of alcohol is suitable for the flame-retardant treatment of thick wood materials. Further, the sticky feeling on the surface of the wood-based material after the flame-retardant treatment is further reduced.

According to the flame-retardant treatment method of the present invention, the flame-retardant composition is fixed simply by coating the surface of the wood material with the flame-retardant composition and drying. Therefore, the heat treatment for fixing is unnecessary, and the flame-retardant treatment can be easily performed. Furthermore, since this flame-retardant composition is highly fluid, when the wood material is subjected to "immersion treatment", the flame-retardant composition penetrates into the wood material in a large amount and the flame retardancy is further improved. Also, it is difficult to be washed out by rainwater.

That is, the wood-based material treated with the flame-retardant composition or the flame-retardant treatment method according to the present invention has extremely high flame-retardant property, good appearance, and excellent durability. In addition, even a wood material having a high water content is likely to be flame-retardant, and the surface does not have unnatural coloration and the natural wood texture is not lost. Since it does not contain chlorine or bromine, it does not generate dioxin or brominedioxin during combustion, and is harmless because it does not occur when ammonia or formaldehyde becomes a product, not only during processing. Furthermore, it has excellent adhesiveness to the paint, and is given antiseptic and ant-preventive effects.

Claims (3)

(57) [Claims] 1. A flame-retardant composition for a wood-based material, which comprises dissolving orthophosphoric acid and urea in water and adding alcohol to the aqueous solution. 2. A method for flame-retarding a wood-based material, which comprises applying the flame-retardant composition according to claim 1 to the wood-based material and then drying the wood-based material. 3. A method for flame-retarding a wood-based material, which comprises immersing the wood-based material in the flame-retardant composition according to claim 1 and then drying the wood-based material.