JPS62288004A - Flame-resistant treatment method of timber - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for flame-retardant treatment of wood, and more specifically, the present invention relates to a method for flame-retardant treatment of wood, and more specifically, it involves pressurizing sawn wood with saturated steam in a pressure cooker. This method involves heating, then treating under reduced pressure, and then impregnating the wood with a fire retardant chemical solution (this relates to a treatment method for making wood flame retardant without changing the surface or appearance of the wood).

[Conventional technology and problems]

Although wood has been widely used as a building material since ancient times, it has the disadvantage of being easily combustible. Various flame retardant treatment methods are known to improve this. One method is to apply fireproof paint to the surface of the wood. This method only makes the surface flame retardant, so if it is exposed to an open flame for a long time)
This has the disadvantage that it is ineffective and changes the surface condition. Also known is a method of impregnating fire retardant chemicals under normal pressure, increased pressure, or reduced pressure. In this method, too, a large amount of the chemical adheres to the surface, but only a small amount of the chemical impregnates the inside, resulting in insufficient flame retardant effect.

As an improvement method for this, Japanese Patent Application Laid-Open No. 59-20605 proposes a flame retardant treatment method for highly impregnable wood by carbonizing the surface of the wood and then impregnating it with a fire retardant solution. This method The flame retardant effect is quite high, but
Note that since the impregnation is near the surface, the flame retardant effect on thick wood is insufficient.

In addition, there is a drawback that the surface turns black or becomes foamy.

[Purpose of the invention]

An object of the present invention is to provide a treatment method for making sawn wood and its surface flame retardant both inside and outside without changing its appearance.

[Structure and operation of the invention]

This is a flame retardant treatment method for wood in which the wood is pressurized, the water vapor is discharged, the wood is treated under reduced pressure, and then the wood is impregnated with a fire retardant chemical solution.

The wood targeted by the present invention is a variety of tree species, including both domestic and foreign conifers and broad-leaved trees, and includes, for example, Douglas fir, Sakhalin fir, Japanese cypress, cedar, red pine, black pine, oak, camphor tree, and the like.

In the present invention, the sawn wood is first fed into a saturated steam inlet.
1 (M++ mHg vacuum and 20
It is stored in a cylindrical pressure cooker that can withstand the pressure of K910n.

Saturated steam is introduced into the pressure cooker, and the temperature is usually 110 to 170°C.
, more preferably at 120-150°C, usually for 1-5 hours, more preferably 2-5 hours, although it varies depending on the thickness of the wood.
Heat and pressurize for 4 hours. Then, the saturated steam is discharged, and the vacuum pump is operated to reduce the pressure in the pressure cooker to 700 mmHg or less, preferably 2007111WHg or less,
Boils and evaporates water contained in wood evenly. 0.5-3
After an hour has elapsed, the operation of the car pump is stopped and the inside of the pressure cooker is returned to normal pressure, after which the wood is sprayed with a fireproof chemical solution for about 30 minutes to evenly impregnate the wood. When the thickness of the wood is as thick as 30 mm or more, it is preferable to repeatedly perform depressurization and injection of fireproofing liquid. The fire retardants used here are known inorganic salts and organic substances, specifically sodium bicarbonate, soda carbonate,
Examples include potassium hydrogen carbonate, potassium carbonate, sodium silicate, ammonium phosphate, ammonium sulfate, phosphoric acid, boric acid, borax, and dicyandiamide. These fire retardants are usually used as a 1-50% aqueous solution by weight.

After the wood impregnated with the fire retardant agent is naturally dried for about a week,
Dry in a hot air dryer for 10 to 30 hours to reduce the moisture content to 1.
It is about 0 to 15 inches and is used for practical use.

〔Effect of the invention〕

The flame retardant treatment method of the present invention removes the resin that makes wood combustible in a pressure cooker, opens the wood cells, and then impregnates the wood with a fire retardant agent. It is absorbed quickly from the outside to the inside, and has a great fire prevention effect. In addition, this treatment does not cause any changes in the surface or appearance, such as color tone, rough skin, cracking, distortion, etc., so a flame-retardant treated material with high commercial value can be obtained.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples. In addition, flame retardancy evaluation was performed by the following method.

Flame retardancy evaluation: The flame of a Bunsen burner with a length of 20 m was applied to the board surface tilted at 45 degrees for 25 seconds, and the presence or absence of ignition was examined.

Example 1 A Douglas fir lumber sawn to a length of 400 mm, width of 100 mm, and thickness of 20 mm was stored in a pressure cooker, and steam at 2/9/cd was fed into the sealed pressure cooker to bring the internal temperature to 130°C, which was maintained for 5 hours. . Then, evacuate the saturated steam and move the inside of the pressure cooker for 150 m.
The pressure was reduced to xHg and left for 2 hours. Thereafter, the pressure was returned to normal, and an aqueous solution containing 3% by weight of boric acid and 3% by weight of borax was sprayed onto the wood for 30 minutes to evenly impregnate it. The treated wood was air-dried for 10 days and then dried in a hot air dryer at 50°C for 20
Dry for an hour. As a result of evaluating the flame retardance of this wood using the method described in Section 2, it was found that it did not catch fire.

Example 2 Instead of an aqueous solution containing 3% by weight of boric acid and 3% by weight of borax, 7% by weight of sodium bicarbonate was added to wood that had been brought back to normal pressure, and the temperature was allowed to drop below 50°C. Example 1 was repeated except that the injection was performed after waiting. The flame retardancy of the treated wood was evaluated using the method described above, and as a result, no ignition occurred.

Example 3 Example 1 was repeated except that instead of the aqueous solution containing 3% by weight boric acid and 3% by weight borax, an aqueous solution containing 3% by weight ammonium sulfate and 3% by weight ammonium phosphate was used. The flame retardancy of the treated wood was evaluated using the method described above, and as a result, no ignition occurred.

Comparative Example 1 Douglas fir wood was milled in the same manner as in Example 1, and an aqueous solution containing 3 parts by weight of boric acid and 3 parts by weight of borax was sprayed for 30 minutes. After air drying for 10 days, it was dried in a hot air dryer at 50° C. for 20 hours. The flame retardancy of the wood was evaluated by the method described in 1. As a result, it was ignited.

Claims (1)

[Claims] The sawn wood is heated under pressure with saturated steam in a pressure cooker,
A method for flame retardant treatment of wood, characterized in that the water vapor is then discharged, treated under reduced pressure, and then impregnated with a fire retardant chemical solution.