JPS626040B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing cellulose fiberboard. Conventional cellulose fiberboards have high specific gravity and high density, and flame-retardant cellulose fiberboards with low density and continuous micropores have not yet been obtained. By making a cellulose fiberboard with low density and continuous micropores, a fiberboard with good heat insulation and sound absorption properties can be obtained. In order to make it flame retardant, it is treated by impregnating or spraying with a flame retardant after paper forming. However, in such a method, the flame retardant is usually only physically attached to the cellulose fiberboard, or even if it is chemically bonded, it is only partially bonded. Therefore, when these methods are used, the applied flame retardant causes problems such as efflorescence, hygroscopicity, chemical pollution, and a decrease in flame retardancy over time, making it impossible to obtain sufficiently flame-retardant cellulose fibers. Not yet. In order to solve the above-mentioned drawbacks, as a result of intensive research, the present inventors reacted a polyvalent metal salt to flame-retardant cellulose phosphate, which had been prepared by treating wood pulp with a low-condensed ammonium phosphate aqueous solution and dried it, and produced paper under acidic conditions. By drying after molding, it became possible to produce a flame-retardant low-density cellulose fiberboard with unprecedentedly low density and bulky continuous micropores. To explain the details of the present invention, cellulose phosphate is produced by impregnating wood pulp with a low condensed ammonium phosphate aqueous solution and then drying it at 130°C to 170°C.
It can be produced by esterification at a temperature of °C. The obtained cellulose phosphate is mixed with water at a rate of about 2.5
Disintegrate with a beater at a concentration of % by weight to obtain pulp slurry. Next, using a solution of polyvalent metal salt, PH2.0~
Adjust to 7.0, preferably 2.7 to 6.5. PH is 2.0
If the pH is lower, no swelling of cellulose occurs and the pH is
If it exceeds 7.0, papermaking becomes difficult. After adjusting the pH, it is formed into a fiberboard using a paper forming machine, and dehydrated by suction to make a fiberboard with a moisture content of about 70%.
Air dry at ℃ for 1-3 hours. The polyvalent metal salts used here include aluminum sulfate, ferric sulfate, ferrous sulfate, zinc sulfate,
Copper sulfate, nickel sulfate, manganese sulfate, magnesium sulfate, aluminum alum, iron alum, sodium alum, potassium alum, chromium alum, Mohr's salt, ferric chloride,
These include aluminum chloride and zinc chloride. Among these polyvalent metal salts, particularly preferred are aluminum sulfate, ferric sulfate, aluminum alum, iron alum, and zinc chloride. It is usually preferable to use these polyvalent metal salts as a 20 to 40% by weight solution. These polyvalent metal salts adjust the pH of the cellulose phosphate fiber slurry, and at the same time, the metal binds to the phosphate groups bonded to cellulose and increases the bulk of the cellulose fiber bundle, resulting in a low-density fiber bundle. It is thought that a paper-made and dried fiberboard can be obtained. The cellulose phosphate fiberboard obtained in this way has a 1.5 to
A fiberboard with 7.0 times the bulk can be obtained, and since it has continuous micropores, it has heat insulation, sound absorption, and dew condensation prevention effects. Because flame retardant treatment is carried out through chemical bonding, fiberboard can be obtained that does not suffer from efflorescence, hygroscopicity, chemical pollution, or deterioration of flame retardancy caused by flame retardants over time.
It is effectively used as a sound absorbing material, a heat insulating material, and a cushioning material, and this fiberboard also passes JIS A 1321 flame retardant class 3. Examples are shown below to clarify the present invention. Example 1 After fully immersing 100 g of NBKP pulp in 150 g of a flame retardant mainly composed of condensed ammonium polyphosphate (manufactured by Otsuka Chemical Co., Ltd., trade name FR-30),
Remove the adhering flame retardant and dry at 80-90°C for 1 hour. At 140℃ to further perform esterification.
Phosphate cellulose fibers reacted in an air bath for 25 min
Obtained 120g. 500g of cellulose phosphate obtained
[Canadian Standard Freeness, CSF (aqueous) = 720 ml] was added to 20 ml of water and disintegrated with a beater, and the pH was adjusted to 2.7 using aluminum sulfate and a 30% by weight aqueous solution to the phosphate cellulose slurry in units of about 2 kg.
After adjusting to ~6.5, thoroughly disperse and process using a paper making machine.
A fiberboard was obtained by molding to 350 x 650 mm. This fiberboard is dehydrated by suction and the moisture content is 70%.
The target fiberboard was obtained by air drying at 125°C. As a control, untreated NBKP pulp was treated under the same conditions to obtain a fiberboard. The measurement results of the thickness and density of each fiberboard are shown in Table 1 below.

【table】

[Table] Example 2 The measurement results of a cellulose fiber board obtained in the same manner as in Example 1 except that aluminum sulfate was replaced with aluminum alum are shown in Table 2 below.

[Table] Example 3 The measurement results of a cellulose fiber board obtained in the same manner as in Example 1 except that aluminum sulfate was replaced with zinc chloride are shown in Table 3 below.

[Table] Γ Flame Retardancy Test The fiberboard obtained in Example 1 was subjected to a flame retardancy test based on the JIS A 1321 flame retardancy test method, and the results are shown in Table 4 below.

【table】

【table】

Claims (1)

[Claims] 1. A flame-retardant low-density product characterized in that cellulose phosphate is disintegrated in water to form a pulp slurry, then treated with a polyvalent metal salt, formed into a paper under acidic conditions, and dried. Method for manufacturing cellulose fiberboard. 2. Cellulose phosphate according to claim 1, wherein the cellulose phosphate is obtained by impregnating wood pulp with a low condensed ammonium phosphate aqueous solution, drying it, and further esterifying it at a temperature of 130 to 170°C. Manufacturing method. 3 The polyvalent metal salt is aluminum sulfate, secondary sulfate
Iron, ferrous sulfate, zinc sulfate, copper sulfate, nickel sulfate, manganese sulfate, magnesium sulfate, aluminum alum, iron alum, sodium alum, potassium alum, chromium alum, Mohr's salt, ferric chloride, chloride aluminum,
The manufacturing method according to claim 1, which is zinc chloride. 4. The manufacturing method according to claim 1, wherein the pH of the pulp slurry treated with the polyvalent metal salt under acidic conditions is in the range of 2.0 to 7.0. 5. The manufacturing method according to claim 4, wherein the PH is in the range of 2.7 to 6.5. 6. The manufacturing method according to claim 1, wherein the drying temperature after paper forming is 100 to 125°C.