FI68099C - FOER REFRIGERATION FOR FLAMMING OF CELLULOSE MATERIAL - Google Patents

Description

m ^ ADVERTISING PUBLICATION /; o Π QQ «flPlp B 11 UTLÄGGNINGSSKRIFT 0 0 0 7 7 C (45> ρ„ Γ "('irj5 (51) Kv.lk.4 / lnt.CI.4 D 21 D 3/00 // D 21 J 1 / 00 FINLAND —FINLAND (21) Patent application - Patentansöknlng 783 & 37 (22) Application date - Ansökningsdag 28 11 78 <F «) (23) Starting date - Glltighetsdag 28.11.78 (41) Published public - Bllvit offentllg 30.05.79

National Board of Patents and Registration ^ Date of display and publication. - _

Patent- och registerstyrelsen 'Ansökan utlagd och utl.skriften publicerad 29 · 03 · ο5 (32) (33) (31) Privilege requested — Begärd priority 29 · 1 1 .77 02.11.78 Sweden-Sweden (SE) 7713 ^ 97 “ 1, 78113 ^ 8-7 (71) Alby Klorat AB, S - 77 ^ + 00 Avesta, Södra Skogsägarna AB, Skogsudden, S-351 89 Växjö, Sweden-Sweden (SE) (72) Mats-Olov Hedblom, Avesta, Zoja Lindh-Nömm, Strömsnäsbruk, Sweden-Sweden (SE) (7 * 0 Forssen s Salomaa Oy (5 * 0 Method for the production of flame-retardant cellulosic material -Förfarande för framstäl1 Ning av flamfast cellulosamaterial

The invention relates to a novel method for making a cellulosic fibrous material flame resistant and in particular to the use of a special drying technique to provide improved temporary or permanent flame resistance to a cellulosic material.

The term "cellulosic material" as used herein means all types of cellulosic pulps from wood chips to cellulose.

The fact that the material is "permanently flame-retardant" means that the material, after immersion and drying for at least three hours when exposed to the flame of a bunsen burner, does not maintain a flame and also does not allow any unwanted afterglow. The fact that the material is temporarily flame-retardant means that the flame-retardancy of the material is lost when the material is exposed to soaking and does not meet the requirements for permanent flame-retardant resistance.

The known methods for making a cellulosic material flame-resistant are based on the principle that the already finished, dried products are impregnated with a flame-retardant chemical in a separate step and then re-dried. However, due to factors such as the shape, density, surface quality, etc. of the products, it presents great difficulties and in certain circumstances it is practically impossible to achieve a sufficiently even distribution of the flame retardant chemical in the product. For similar reasons, subsequent drying is often associated with major problems.

It is an object of the present invention to provide a flame retardant material in which a flame retardant chemical is evenly distributed within a cellulosic material.

Another object of the invention is to provide a flame-retardant cellulosic material, which material is always desired to be permanently or temporarily flame-retardant by a simplified process having an impregnation step before drying the cellulosic material, whether or not a flame retardant cellulosic material is desired. The flame protection step is thus included as an integral part in the production of the cellulosic material, which material is then shaped in different ways depending on the intended end use. This means that, compared to known methods, one drying step can be completely eliminated.

The advantages presented according to the present invention are achieved in that the primarily aqueous cellulosic material is impregnated with a flame retardant chemical dissolved or suspended in water, the impregnated material is decomposed, e.g. torn, and optionally fluffed, and the material thus obtained is dried and optionally cured. with a warm, predominantly turbulent gas flow which at the same time conveys the cellulosic material inside the drying (and curing) system.

Impregnation with a flame-retardant chemical can take place in a known manner, in which case it is essential that the impregnation takes place in such a way as to obtain an even distribution of the chemical within the cellulosic material. In order to increase the penetration of the impregnating agent, a surfactant can be added. The impregnating agent, i.e. a flame-retardant chemical or a combination of several different chemicals, is then dissolved or suspended in water. The invention is not limited to any particular type of flame retardant chemical, but it is, of course, suitable to select chemicals which do not interfere with the temperature used for drying and possibly curing or which cause environmental contaminants. Examples of suitable liekinsuojäävistä chemicals are phosphoric acids, amidofosforihapot, airnnoniumfos- phosphates, ammonium sulfate, aimnoniumsulfamaatit, ammoniumamidofos-phosphates, ammoniumamidopolyfosfaatit, ammonium, boron acid, sodium borate, aluminum hydroxide, ammonium chloride, am bromide, kaliumaluminiumsulfaatti, antimony oxide in combination with a halogen, phosphates or .fosforihappo together with urea, the concentration of the flame retardant chemical must be sufficient to provide a flame retardant material, and the effective amount of the flame retardant chemical usually rises to about 5-60% by weight based on the dry mass.

Before the dipped or impregnated material enters the drying system, it is important that the material be subjected to mechanical disintegration, such as tearing and possibly fluffing, so that it acquires a suitable shape for further processing in the drying system.

The impregnated and appropriately comminuted cellulosic material is then introduced into a drying system where it encounters a warm gas stream whose flow rate exceeds the fluidization rate of the incoming material. It is suitable that the gas flow in the drying system is turbulent and that the fibers in the cellulosic material are mainly in the form of free fibers.

In order to control and regulate the drying and possible curing, it is suitable to provide a heating element, such as an oil burner, at one or more points in the drying system, as well as to remove water vapor formed when heating the cellulosic fibrous material. The separation of water vapor from the cellulosic fibrous material can advantageously take place in a cyclone-type separator. By arranging in this way one or more drying devices and one or more separators in the drying system, the dilution-drying (curing) process in the cellulosic fibrous material can be advantageously controlled and adjusted and the drying and curing of the spent cellulosic starting material pro rata.

One type of dryer that works according to the principle presented is the so-called flake dryer. This dryer is used to dry various pulps, but has never before been used to dry flame-retardant cellulosic material.

The drying process of the present invention forms a combination of a flame retardant and cellulosic fibers to obtain a fibrous cellulosic material that is flame resistant without being permanently flame resistant, which is completely satisfactory for many purposes. However, if it is desired to produce a material which is permanently flame-retardant, certain flame retardants such as phosphoric acid or ammonium phosphates with urea or ammonium salts of amidoxosphoric acids or amidopoly-phosphoric acids are optionally reacted with the urea and further between the fibers and the flame retardant, temperatures during excavation and possibly curing as well as residence time in the drying (and curing) system will, of course, vary depending on the cellulosic feedstock used, flame retardant chemical and desired end product and can be determined by simple experiments.

The present invention is further illustrated by the following examples:

Example 1

A pulp dryer made of fully bleached cellulose was introduced into a flake dryer equipped with three drying steps in a conventional manner. After the dewatering press, but before the coarse and fine tearing steps, the pulp was impregnated with a 50% ammonium polyphosphate solution by spraying so that it contained 25% of ammonium polyphosphate, calculated on the dry mass. About 1 minute. after the addition of the flame retardant, a sample of the effluent dried pulp was taken, which was flame resistant.No exceptions in the production process could be observed.

Example 2

The experiment of Example 1 was repeated, but the addition of flame retardant was about 15%.

The extracted mass showed satisfactory flame resistance.

Example 5

The experiment of Example 1 was repeated, but about 205% of ammonium sulfamate based on dry weight was added. The floated pulp had satisfactory flame resistance.

Example A

To a dissolution vessel containing 60 parts of water were added with vigorous stirring 20 parts of finely divided chloric acid and 20 parts of finely divided borax. The mixture was heated to 60 ° C for about 2 hours, at which time most of the added powder dissolved.

In the same manner as in Example 1, the mixture was added to an amount of up to 20% by dry weight based on dry mass.

The floated pulp sample had good flame resistance.

Example 5

Anhydrous reaction product NH3-P2O5 (prepared by burning elemental phosphorus with dry air to produce a mainly gaseous 72 ^ 5 which was reacted immediately with an excess of UH ^ in excess of the amount reacting with PgO4 and separating the reaction product in the form of a white powder) which containing 6.5% anide nitrogen, was dissolved in water to a concentration of 50%, after which the pH was adjusted to 6.5 by adding ammonium hydroxide solution. In the same manner as in Example 1, the solution was added to a wet volume of 20% (calculated as dry).

The extracted pulp sample proves to be very flame resistant.

68099

Example 6

The experiment was performed in the same manner as in Example 5, but with the difference that the temperatures in the three drying steps of the flake dryer were increased above normal. Under the other conditions used, the following outlet temperatures for the gas were measured at different drying stages:

drying step 1 about 100 ° C

drying step 2 about 140 ° C

drying step 3 about 180 ° C

The extracted mass showed permanent flame resistance properties.

Claims (4)

7 68099 A process for producing a fibrous, flame-retardant, cellulosic material by impregnation with a refractory chemical dissolved or suspended in water, characterized in that the material is decomposed and optionally fiberized after impregnation, and the material thus obtained is dried in a flake-dry state and optionally cured. Process according to Claim 1, characterized in that an aqueous, cellulosic material is used. 10 A method according to claim 1 or 2, characterized in that the water vapor generated in the system is separated from the cellulosic material and removed from the system. Method according to one of the preceding claims, characterized in that the impregnated cellulosic material is decomposed so that it is mainly in the form of free fibers during the drying (curing) process.