Discussion on fire prevention and flame retardancy

2022-07-24
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As the saying goes: in 2016, ncm622, ncm811 and NCA with high nickel accounted for more than 5% of the total output of three yuan materials in China. Paper is one of the objects of fire. People have a natural fear of fire, and paper packaging is even worse. Therefore, paper packaging has always been the focus of fire protection. This paper is devoted to the exploration of the theory of fire prevention and flame retardancy of paper packaging, in order to improve the protective performance of paper packaging through the research on fire prevention and flame retardancy of paper packaging mouth

we know that whether paper or paperboard, they are all interwoven with fibers. The paperboard commonly used for paper packaging is made of plant fiber. Because of the flammability of its basic component - plant fiber, the study on the combustion mechanism of paper or paperboard is determined. It is of special significance to use certain technical means and processes to improve the fire resistance of paper or paperboard

early studies showed that when paper was burning, the multi-faceted pyrolysis in front of the flame produced gases. As a result of the movement of air and these gases, the flame moved, diffused and spread along the paper surface, and the paper surface was heated to the decomposition temperature. However, recent studies have shown that during combustion, the gas produced by paper pyrolysis is under the flame. As the gas diffuses, the flame spreads out of the pyrolysis zone. At the same time, due to the heat conduction in the phase, the adjacent paper surface is heated to the thermal decomposition temperature if there is oil stain, which is the combustion mechanism of the paper

it can be seen from the combustion mechanism of paper that in order to endow paper with fire resistance, we must start from the following three aspects:

1. Isolate the paper surface and flame, and prevent the flame from burning and spreading on the paper surface

2. Reduce or consume oxygen in the combustion environment and suffocate the flame

3. Reduce the temperature in the combustion zone or use fire-resistant fibers to prevent paper pyrolysis

the fireproof paper produced by various processes and methods has no more than the above three mechanisms. For example, the paper is impregnated with NaHCO3 solution to give it fire resistance and emit incombustible gases such as water vapor and carbon dioxide, which can asphyxiate the flame; For example, borax, boric acid, water glass and other substances are added to the paper. These substances form a glassy protective layer at the place where they burn in the paper under high temperature, so as to isolate the paper surface from the flame and prevent the flame from burning and spreading on the paper surface; If ammonium salt is added to the paper, the incombustible helium will be released, which will absorb heat, so as to asphyxiate the flame and reduce the temperature of the combustion area and the surrounding air

there are many methods and technologies to endow paper with fire resistance, but there is no mature technology for the fire resistance of paper packaging. If we use fireproof cardboard to produce paper packaging, we can certainly achieve the purpose of resistance. However, compared with the general packaging paperboard, the use of fireproof paperboard is not desirable in terms of economic benefits. The most convenient and effective way to use ordinary packaging paperboard and endow paper packaging with fire resistance is to add fire retardant to the adhesive

there are many known fire retardants. In addition to the above mentioned, there are guanidine salt, water-soluble guanidine based salt, nepheline free, gaseous helium, halogen derivatives, oxidation, etc. Among all these numerous fire proofing agents, which one or several fire proofing agents can not only endow paper packaging with fire resistance, but also be suitable for the production of paper and silk packaging industry? This is a heavy and meaningful job

the following principles must be followed when selecting fire retardant:

first, the physical properties of the existing adhesive shall not be affected, or the physical properties of the mixture added with fire retardant shall meet the production requirements

the physical properties of the adhesive include fluidity, viscosity and strong adhesion

II. The selected fireproof agent shall be cheap and easily available

for manufacturers using water glass as adhesive, there is no need to add additional fireproof agent, because water glass itself is a kind of fireproof agent. As the paper packaging products produced with sodium silicate have some shortcomings, such as brittle, easy to get damp and white, most manufacturers have turned to starch adhesive. In the preparation of starch adhesive, a certain amount of borax should be added. As we know, borax is a kind of fire retardant, but the dosage in starch adhesive is very small, generally about 0.4%, so the fire retardant effect is not obvious

for each kind of adhesive with fluidity, there is an optimal viscosity and surface tension index. Any tendency to deviate significantly from the best indicators will have an adverse impact on the quality of the adhesive and its application. Therefore, the influence of fire retardant on adhesive must be considered when selecting fire retardant

among many fire proofing agents, some will reduce the fluidity of the adhesive. The mixed buffer high performance plus is the strongest mixed buffer material designed by Pregis. Others will improve the fluidity of the adhesive. Therefore, in the production of paper packaging products with fire-retardant effect, at least two or more fire retardants should be added to the adhesive. One of them must be able to reduce the fluidity of the adhesive; The other can improve its fluidity. The total amount of fireproof agent is determined according to the fire resistance of paper packaging, and the ratio of various materials is subject to the best flow index. In order to endow paper packaging with fire resistance, the viscosity and surface tension of adhesives should be controlled

if urea based resin is added to the starch adhesive and sodium bromide and ammonium chloride are added to the composite material, the price is high, then paper packaging products with good fire resistance, flame retardancy, moisture resistance and water resistance can be prepared. The following methods can also be adopted:

30 parts of the mixture of starch and urea based resin; Ammonium chloride 31.5 parts

9.9 parts of sodium bromide; Water 70 points

direct preparation of adhesive for the production of paper packaging products can produce paper packaging products with good fire and water resistance. The experiment shows that the paperboard bonded and laminated with this adhesive does not burn on the Bunsen lamp, and there is no spark when moving out of the flame. The control sample ignited immediately and burned completely on the Bunsen burner

to sum up, the development of fire resistant paper packaging is technically feasible, with good economic benefits and certain social benefits. It is believed that through the in-depth study on the fire prevention and flame retardance of paper packaging, the protective performance of paper packaging will be improved day by day, and its passive and weak position of being inaccessible to fire will be completely changed

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