When establishing a polyurethane foam factory, careful consideration of the site selection and construction conditions is crucial for its success. Several principles guide the selection of the factory site:

Firstly, the principle of optimizing and reorganizing existing resources of project units is essential. This ensures that the factory can make the best use of available resources without unnecessary duplication.

Secondly, the principle of saving land and reducing investment is vital. By selecting a site that is efficient in its land use, the factory can minimize costs and maximize efficiency.

Thirdly, the principle of facilitating transportation and reducing product production costs is significant. A location that allows for easy transportation of raw materials and finished products helps in lowering overall production costs.

Lastly, the principle of preventing urban pollution and protecting the environment is paramount. Choosing a site away from densely populated areas helps in reducing the impact of factory operations on the city's environment.

In addition to these site selection principles, various factors related to construction conditions must also be considered:

Geographic location and transportation conditions play a crucial role. An ideal location would have good access to transportation networks, such as highways or railways, facilitating the movement of goods.

Resource status and social conditions are important factors. This includes assessing local service supporting facilities, availability of labor resources, and government policies that might affect the factory's operations.

Natural conditions, such as climate, geological factors, and seismic considerations, should not be overlooked. Understanding these factors helps in planning for any potential risks or challenges during construction and operation.

Factory construction conditions such as water supply, drainage, power supply, and heating are essential for the smooth functioning of the facility. Adequate provisions for these utilities must be ensured during the planning stages.

In conclusion, the successful establishment of a polyurethane foam factory hinges on a thoughtful analysis of both site selection principles and construction conditions. By adhering to these considerations, the factory can be set up in an optimal location with the necessary infrastructure for efficient and sustainable operations.

Density:

A. PU flexible foams with high density have many small pores, appearing fuller. However, the higher the density, the poorer the water absorption.

B. Generally, PU flexible foams with high density also have high hardness, but it is not ruled out that some high-density foams may add super soft additives, making the sponge very soft. Therefore, PU flexible foams of the same density may have different degrees of softness or hardness.

C. High-density foams are often used for sound-absorbing cotton, sofa cushions, soft packaging materials, etc. Medium and low-density foams are generally used for protective materials.

Resilience:

A. Slow rebound foams, also known as inert foams, memory foams, zero-pressure feeling foams, etc. Slow rebound foams have a "honeycomb" structure, so they cannot quickly return to their original shape after being compressed.

B. Characteristics of slow rebound foams: good water absorption, sound insulation performance; strong toughness, high tensile strength, good shock absorption and cushioning performance; good heat insulation and thermal insulation, can withstand severe cold and heat.

C. High rebound foams have a mixture of pore sizes, different skeleton thicknesses, and a high open hole rate. When compressed, they produce rebound forces with different supporting forces in different deformation states.

D. High rebound foams have super strong resilience and breathability; excellent anti-fatigue performance and flame retardancy; the feel is similar to latex surface.

In annual fire incidents, a significant proportion of ignitions are caused by foam, including sofa fires and various ignitions from soft packaging. These incidents occur far too frequently. How can we fundamentally eliminate or reduce such events?

One effective approach is to start from the source materials, much like treating the root cause of an illness. Adding flame retardants to polyurethane foam can effectively prevent ignition.

Now, let's understand flame-retardant foam:

Flame-retardant foam, also known as fire-resistant foam, has a chemical name of polyurethane foam material, which is divided into soft foam (mainly used for furniture) and rigid foam (mainly used for insulation). Generally, it is a fireproof material synthesized by adding various flame retardants to polyurethane.

The product's fire-retardant effect meets the requirements of ASTM Standard 117 and national standards. The usage method is the same as regular foam.

The combustion of polymers is a very complex and intense oxidation reaction. The process occurs as the polymer is continuously heated by an external heat source, initiating a free radical chain reaction with oxygen in the air. This releases some heat, further intensifying the degradation of the polymer, generating more flammable gases, and making the combustion more severe.

There are two methods for the flame retardancy of fire-resistant foam:

One is to chemically introduce flame-retardant elements or groups containing flame-retardant new elements into the molecular structure of the foam. The other method is to add compounds containing flame-retardant elements to the foam. The former method uses flame-retardant substances called reactive flame retardants, while the latter method uses substances called additive flame retardants.

Currently, the vast majority of flame retardants used in foam are additive flame retardants, while reactive flame retardants are mainly used in thermosetting resins such as epoxy resins and polyurethanes. The primary function of flame retardants is to interfere with the three basic elements required for combustion: oxygen, heat, and fuel. This can generally be achieved through the following means:

Flame retardants can produce heavier non-flammable gases or boiling liquids that cover the surface of the foam, interrupting the connection between oxidation and fuel.

By absorbing heat through decomposition or sublimation, flame retardants reduce the surface temperature of the polymer.

Flame retardants generate a large amount of non-flammable gases, diluting the concentration of flammable gases and oxygen in the combustion area.

Flame retardants capture radical free radicals, interrupting the chain reaction of oxidation.

Understanding the principles behind foam reactions is crucial. To master foaming, we must strive to establish a foam reaction model in our minds using the following four reaction equations. Through familiarity with the variations within the model, we cultivate sensitivity that allows us to comprehend the entire foam reaction process. This approach helps structure our knowledge base and professional skills in polyurethane foam. Whether actively studying foam reaction principles or passively exploring them during the foaming process, it serves as a vital means for us to deepen our understanding of formulations and enhance our skills.

Reaction 1

TDI + Polyether → Urethane

Reaction 2

TDI + Urethane → Isocyanurate

Reaction 3

TDI + Water → Urea + Carbon Dioxide

Reaction 4

TDI + Urea → Biuret (Polyurea)

01: Reactions 1 and 2 are chain-growth reactions, forming the main chain of the foam. Before the foam reaches two-thirds of its maximum height, the main chain rapidly elongates, with chain-growth reactions predominating inside the foam. At this stage, due to relatively low internal temperatures, reactions 3 and 4 are not prominent.

02: Reactions 3 and 4 are cross-linking reactions, forming the branches of the foam. Once the foam reaches two-thirds of its maximum height, the internal temperature rises, and reactions 3 and 4 intensify rapidly. During this stage, reactions 1 to 4 are vigorous, marking a critical period for the formation of foam properties. Reactions 3 and 4 provide stability and support to the foam system. Reaction 1 contributes to foam elasticity, while reactions 3 and 4 contribute to foam tensile strength and hardness.

03: Gas-producing reactions are termed foaming reactions. The generation of carbon dioxide is a foaming reaction and the primary exothermic reaction in polyurethane foam. In reaction systems containing methane, the vaporization of methane constitutes a foaming reaction and an endothermic process.

04: Reactions leading to the formation of foam constituents are known as gelation reactions, encompassing all reactions except for gas-producing reactions. This includes the formation of urethane, urea, isocyanurate, and biuret (polyurea) from reactions 1 to 4.