JPS6120312B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an aqueous membrane fire extinguishing foam. Aqueous membrane fire extinguishing foams using fluorine-based surfactants are extremely effective against fires caused by highly flammable substances such as gasoline, naphtha, ether, and benzene, and have been extensively researched and have many patent applications filed. is being done. The feature of aqueous film fire extinguishing foam using fluorine-based surfactants is that it forms a thin aqueous film and stable foam on the surface of flammable materials, allowing for rapid extinguishing and prevention of sustained re-ignition. It is in. However, in order to prevent large-scale fires in tanks in petroleum complexes, there is a strong need for the ability to form an aqueous film and the stability of foam on the tank walls that are heated to high temperatures and on the surface of the heated and boiling oil. . In order to deal with this problem, for example,
Publication No. 26160 proposes a method for improving foam mobility and flame resistance using surfactants derived from tetrafluoroethylene oligomers.
Furthermore, JP-A-49-52498 discloses that a fire extinguishing agent with excellent foam stability and spreadability can be obtained by using a cationic surfactant having a perfluoroalkyl group and a hydrocarbon amphoteric surfactant in combination. It is stated that. However, in all formulations, the fire resistance of the foam is insufficient, and further improvement is desired for practical purposes. The present inventor conducted a comparative study on the fire resistance performance of a huge variety of fluorine-containing surfactants, and discovered the general formula derived from hexafluoropropene trimer or tetramer: [In the formula, A is SO ₂ or CO, R is an alkyl group having 6 or less carbon atoms or a benzyl group (they may be the same or different), X is a halogen or a lower alkyl sulfate residue, and m represents 3 or 4] has been found to have significantly superior fire resistance properties, and the present invention has been completed. The compound represented by the general formula [] can be obtained, for example, by the method described in JP-A-51-11084. Outstanding effects cannot be expected from hexafluoropropene oligomer derivatives other than those derived from trimers and tetramers. For A, SO ₂ or CO is particularly effective. R is a lower alkyl group, preferably an alkyl group having 6 or less carbon atoms or a benzyl group. three Rs
may be the same or different. X is a halogen or lower alkyl sulfate residue, typically an iodine, bromine, chlorine, dimethyl sulfate or diethyl sulfate residue. The aqueous membrane fire extinguishing foam of the present invention may contain suitable additives that have been used in conventionally known fluorine-based fire extinguishing foams, and are usually used in combination. For example, foam stabilizers such as polyethylene glycol, polyvinyl alcohol, carboxymethyl cellulose, etc., solubilizing and foam stabilizers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and storage stabilizers for formulations at low temperatures. In addition, ethylene glycol, lower alcohol, etc. may be used in combination with a non-fluorine surfactant as an auxiliary agent to improve foaming properties and spreadability. It may also be used in combination with other fluorine-containing surfactants. Further, the present invention provides a compound represented by the above [] with the formula: C _o F _2o+1 CH ₂ CH ₂ CON(CH ₂ CH ₂ OH) ₂ [] [wherein n is an integer of 6 to 8] By using the compound in combination, even more excellent fire resistance performance can be obtained. For example, the compound represented by the formula []
It can be obtained from polyfluorocarboxylic acid obtained by hydrolyzing polyfluoronitrile obtained by the method described in Publication No. 30820, and has almost no fire resistance by itself. The most favorable result is obtained by mixing compound [] with compound [] in approximately equal amounts, and it is possible to replace up to about 80% of compound []. If used in excess, the fire resistance will deteriorate. The aqueous membrane fire extinguishing foam of the present invention contains the above compounds [] or [] and [] in the diluent at the time of use.
It is preferable to formulate the compound in an amount of 0.1 to 0.5% by weight/volume, and even when used in combination with conventionally known fluorine-based aqueous membrane fire extinguishers, sufficient effects cannot be obtained unless it is present in an amount of at least 0.05%. The use of 0.5% or more is for economic reasons, and the effect is further improved by using more than 0.5%. Since aqueous membrane fire extinguishing foam is usually used at 3% by volume or 6% by volume, the formulation may be determined accordingly. The present invention will be explained below with reference to Examples. Example 1 A circular iron container with an inner diameter of 140 mm and a depth of 40 mm is used. The container was divided into two parts along the diameter by a partition wall having a height of 40 mm and a thickness of 1.6 mm, and a gap of 3 mm was provided between the partition wall and the bottom of the container. Add 200 ml of n-heptane to this container. On the other hand, the test fluorine-based surfactant 0.2W/V%, diethylene glycol monobutyl ether 1.8W/V
% of the aqueous solution is mechanically foamed and the entire volume is poured into one side of the container separated by the partition wall. The n-heptane on the other side is ignited, and the time required for the bubbles to collapse by combustion and for the flame to spread over the entire surface is measured. The measurement was performed five times and the average value is shown in Table 1 as the fire resistance capacity.

【table】

[Table] Example 2 45ml of liquid was poured into a circular iron container with an inner diameter of 140mm and a depth of 100mm.
Add 200 ml of n-heptane at ±2°C. On the other hand, fluorine surfactant 0.2W/V%, ethylene glycol monobutyl ether 1.8W/V% and non-fluorine surfactant (C ₁₂ H ₂₅ NH
(CH ₂ ) ₂ COOH) Mechanically foam 50 ml of an aqueous solution containing 0.1 W/V% to make 7 times the foam. Pour the entire amount of this foam onto the above n-heptane, and after 1 minute, place a small plate with an inner diameter of 35 mm that has been ignited with n-heptane in the center of the container, and gently submerge it into the foam to see how the flame spreads and how it is extinguished. observed. Table 2 shows the time required for flame extinguishing or expansion as fire resistance. Two minutes after extinguishing the fire in the test, a flame was brought close to the foam surface and it was observed whether the n-heptane would re-ignite.The results are shown in Table 2 as sealing properties. The fluorine-containing surfactants tested were the same as in Example 1, and corresponded to the numbers in Table-1.

【table】

【table】

Claims (1)

[Claims] 1 General formula derived from hexafluoropropene trimer or tetramer: [In the formula, A is SO ₂ or CO, R is an alkyl group with 6 or less carbon atoms or a benzyl group, which may be different, X is a halogen or a lower alkyl sulfate residue,
m represents 3 or 4] is an aqueous membrane fire extinguishing agent containing a compound represented by the following as an essential component. 2 General formula derived from hexafluoropropene trimer or tetramer: _[ In the _{formula , A , R and} An aqueous membrane fire extinguishing agent containing as an essential component a compound represented by an integer of 6 to 8.