Fire hazard analysis and countermeasures of polyurethane foam sealant production process

[abstract] based on the basic production principle and characteristics of polyurethane foam caulking agent, fire hazard analysis was carried out on the raw materials. The safety problems and causes in the production of polyurethane foam sealant are put forward. The fire hazard of polyurethane foam caulking agent production process was quantitatively evaluated by hazard evaluation method. The countermeasures to prevent fire accidents are put forward from the aspects of building design, fire prevention management and production technology.

【 key words 】 polyurethane foam caulking agent; The raw material; Production process; Fire hazard; Risk assessment method; Prevention countermeasures

0 the introduction

Polyurethane foam caulking agent is a new type of construction and installation material. The product is a polyurethane foam expansion filler material that USES polyurethane material characteristics and adopts the form of aerosol to realize the single-group dispensing foam process. It is specially used for the crack treatment of building components. It can replace traditional caulking materials such as cement mortar, rock wool, wool top and silica gel, so as to achieve the tightness of crack treatment of building components and play the role of heat preservation, heat insulation, sealing and delaying the spread and expansion of fire [1]. Therefore, the domestic introduction of polyurethane foam sealant manufacturers are increasing year by year.

Due to the particularity of polyurethane foam production process, fire risk exists in every link of production process. However, most manufacturers in China do not have the ability to develop experimental products. They only buy the formula temporarily and produce according to the formula. They do not know enough about the raw materials and process characteristics of their chemical products and the quality requirements for the filling of pressure-resistant aerosol cans [2]. In addition, in the domestic and foreign mandatory standards for this kind of products, only the combustion performance of finished products is stipulated in the fire protection, and the potential fire hazards in the production process are not specially considered, resulting in a certain impact on the fire protection supervision work of fire law enforcement personnel, and also causing safety and quality hazards for manufacturers. Therefore, most manufacturers have experienced container e xplosion phenomenon in the process of filling or transportation to varying degrees, and some manufacturers even caused fires, causing unnecessary injuries and huge property losses. Such as:

A factory in northeast China in 2004. In May 2005, because hundreds of boxes of products did not reach enough cooling time after shaking, the stack exploded and caused a fire, causing direct losses of more than 100,000 yuan.

On October 14, 2004, the construction site of a food processing plant in tianjin, because operators use hot halogen tungsten lamp, roast burning fire, polyurethane foam gap filling agent combined with a lack of fire water supply of construction site and the corresponding fire extinguishing equipment, although the fireman to save, still eventually lead to the direct and indirect economic losses of more than 13 million yuan.

In view of the above situation, it is of great significance to analyze and study the fire risk of polyurethane foam caulking agent production process and put forward the corresponding prevention countermeasures, so as to improve the fire precontrol ability of this process and ensure its safe production.

Polyurethane foam caulking agent and its production process

1.1 basic principle and characteristics of the product

Polyurethane foam caulking agent is sprayed out by canning spray agent. After spraying, the volume of polyurethane foam expands rapidly and reacts with water in the air to form a uniform semi-rigid foam body, so as to fill, seal, bond, fix and prevent the spread of fire.

Polyurethane products have the following main performance characteristics:

1) single-group bubble filling, quick filling, simple construction, high efficiency and little labor.

2) high filling degree to ensure full sealing.

3) when the product is filled with foam, excess foam can flow out from both sides of the crack, which will not negatively affect the extrusion deformation of the door and window frame.

4) can be firmly bonded with cement mortar and PVC board.

5) foam has no corrosive effect on PVC frame material.

6) uniform semi-rigid closed-hole material can be formed after curing, which can be waterproof, soundproof and hinder air circulation, ensure the sealing around Windows, and prevent the spread of fire.

7) after the foam solidifies, the expanded part is easy to repair and can be cut with cutting tools, which is convenient and quick.

8) the surface can be protected by coating and latex paint brush to prevent ultraviolet radiation from aging the material, and the service life can be more than 50 years.

9) semi-rigid polyurethane foam belongs to the elastomer connection, which can prevent the adverse effects caused by thermal expansion and cold contraction of the frame, and has the effect of shock absorption and shockproof.

10) material does not spontaneously ignite, which can be automatically extinguished after the fire source is removed.

11) curing foam is resistant to temperature change (temperature change range: -30~100℃), solvent, acid and alkali erosion, and the product has strong applicability.

12) no freon, no effect on ozone layer, no harm to human body. The strong sealing of foam can reduce the loss of energy, belongs to environmental protection and energy saving materials.

1.2 introduction to the production process of polyurethane foam caulking agent

Polyurethane foam sealant is stored in a single pressure tank with polyurethane prepolymer, foaming agent and injection agent as raw materials. Its main raw materials are: dimethyl ether, propane, butane, silicone oil, isocyanate, polyether and so on. The main raw material of prepolymer is isocyanate, the main raw material of foaming agent is dimethyl ether and propane, the ratio of dimethyl ether and propane has a great influence on foaming agent. Polyurethane foam sealant was filled into a 750-ml pressure-resistant tinplate tank with an aerosol tank, which was filled with 260 g of combination polyether, 350 g of isocyanate, propane and dimethyl ether, 135 g in total. The mixture was subjected to chemical reaction, then vibrated for 10 min and placed at room temperature for 24 h to obtain the final product [3]. The production process is shown in the following figure.

1.3 raw materials and fire risk

Some raw materials of polyurethane foam sealant have fire hazard to varying degrees, which is the main factor leading to fire hazard of polyurethane foam sealant production process.

1.3.1 dimethyl ether

Dimethyl ether (CH3OCH3) is a new type of fuel. It is a colorless, slightly mellow gas that mixes easily with air and is flammable. Dimethyl ether (LPG) has similar physical properties to LPG and can be used as a clean fuel for civil use as an alternative to fuel oil, LPG and city gas [4]. The physical and chemical properties of dimethyl ether are shown in table 1.