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.

Polyurethane soft foam plastic is one of the important products in the polyurethane industry. Its production necessarily involves the use of organic amine catalysts, especially organic tertiary amine catalysts. This is because organic tertiary amine catalysts play a significant role in the main reactions of polyurethane foam formation: the reactions of carbon dioxide and molecular polymerization, promoting rapid expansion of reaction mixtures, increased viscosity, and sharp increase in polymer molecular weight. These conditions are essential for the formation of foam bodies, ensuring that soft foam plastics have advantages such as low density, high strength-to-weight ratio, high resilience, and comfort for sitting and lying. There are many types of organic amine catalysts that can be used for polyurethane soft foam plastics. Among them, the highly efficient catalysts recognized by various manufacturers are: triethylene diamine (TDEA) and bis(dimethylaminoethyl) ether (referred to as A1). These are also the most widely used organic amine catalysts in the world today, with the highest consumption among various catalysts.



Due to the molecular structural differences between TDEA and A1 catalysts, there are significant differences in their catalytic performance, particularly in their reactions to carbon dioxide gas and molecular polymerization. If the user does not pay attention to these differences in production, not only will they fail to produce qualified foam products, but it will also be difficult for foam bodies to form. Therefore, understanding and mastering the performance differences between these two catalysts in polyurethane foam production is of great significance. TDEA exists in a solid state under normal conditions, making its application less convenient. In actual production, low molecular weight alcohol compounds are commonly used as solvents, formulated into 33% solutions for ease of use, commonly referred to as A33. On the other hand, A1 is a low-viscosity liquid that can be directly applied. Below is a comparison of the catalytic performance differences between A1 and A33 in the production of polyurethane soft foam plastics.



A33 has a 60% catalytic function for the reaction with carbon dioxide gas and a 40% catalytic function for molecular polymerization. It has a low effective utilization rate of carbon dioxide gas, resulting in lower foaming height and higher foam density. Since most of the catalytic function is used for molecular polymerization reactions, it is easy to produce closed-cell foam bodies, which are stiff with low rebound, and the adjustable range of tin catalysts becomes narrower. To achieve the same catalytic function, the amount used is 33% more than A1. Both the bottom skin and outer skin of the foam body are thicker. Increasing the amount can increase the reaction speed, but the amount of tin catalyst must be reduced accordingly, otherwise closed-cell foam bodies will be produced.



A1 has an 80% catalytic function for the reaction with carbon dioxide gas and a 20% catalytic function for molecular polymerization. It has a high effective utilization rate of carbon dioxide gas, resulting in higher foaming height and lower foam density. Since most of the catalytic function is used for gas generation reactions, it is easy to produce open-cell foam bodies, which are soft with high rebound, and the adjustable range of tin catalysts becomes wider. To achieve the same catalytic function, the amount used is less than A33. Both the bottom skin and outer skin of the foam body are thinner. Increasing the amount can increase the reaction speed, but the amount of tin catalyst must be increased accordingly, otherwise over-foaming and cracking may occur.



In terms of overall performance between TDEA and A1, A1 has a higher comprehensive catalytic performance than triethylene diamine. Its actual application effects are also better, although not as convenient as triethylene diamine in terms of transportation and storage. Currently, the vast majority of mechanical continuous foam production facilities almost exclusively use A1, while all box-type foam production facilities use TDEA. However, this is not absolute. With a clear understanding of the differences between the two and appropriate formulation adjustments, they can be interchangeable and both can produce excellent foam products.

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.

Calculation of foaming distance for continuous foaming machine



Given: Bubble release time for the formula is 108 seconds, conveyor belt speed during foaming is 4.6 meters per minute. Calculate the swinging and trough foaming distances.

Foaming distance when swinging: (108/60) x 4.6 = 8.28 meters

Foaming distance when troughing: [((108-18)/60)] x 4.6 = 6.9 meters



Explanation: For the same formula, continuous foaming machine has a shorter bubble release time than small bubbles. The calculated foaming distance is shorter than the actual foaming distance. This method only provides approximate confirmation of the foaming distance, supporting the adjustment of the settling plate. Troughing: 18" indicates the time in seconds that the raw material stays in the overflow trough.



Calculation of foaming height for continuous foaming machine



Given: Formula flow rate: 80 kilograms per minute for polyether, 20 for white polyether, 60 for TDI, 20 for stone powder, conveyor belt speed 4.5 meters per minute, mold width 1.65 meters, producing foam with a density of 25 kilograms per cubic meter. What is the foaming height in meters?

Total formula weight: 80 + 20 + 60 + 20 = 180 kilograms

Formula volume: 180/25 = 7.2 cubic meters

Base area of conveyor running per minute:

4.5 x 1.65 = 7.425 cubic meters

Foaming height: 7.2/7.425 = 0.97 meters



Explanation: Silicone oil, amine, and tin are not considered here as they offset the amount of carbon dioxide used during the foaming process. Moisture content (MC) is not considered because MC does not increase foam weight when vaporized.



Foaming Daily Operation

Beginners worry that improper adjustment of the settling plate will cause the liquid sprayed from the nozzle to surge forward or backward, affecting foaming. The reaction rate gradually increases within the first two minutes after starting the machine, sometimes requiring corresponding adjustments to the settling plate. Adjustments to the settling plate are more critical in formulas with low density and high MC.

TDI flow rate can be calculated by determining the corresponding scale value for the flow rate, but it is recommended to measure the TDI flow rate during the first foam production. Flow rate is too important; if the flow rate is incorrect, everything else will be a mess. It's best to rely on the simplest and most intuitive method of measuring flow rate.

When powder is being mixed, the mixed stone powder should be left overnight and production should start the next day. For formulations containing melamine and stone powder, it is recommended to first mix the melamine with the polyether for a period of time before adding the stone powder.

Formulas for foam machines with longer mixing chamber or more teeth on the mixing shaft typically have less amine and lower material temperature. Conversely, formulas for foam machines with shorter mixing chamber or fewer teeth on the mixing shaft typically have more amine and higher material temperature.

For the same formula, when switching between dual spray swing heads and single spray swing heads, if the cross-sectional area of the two nozzles is similar, the requirements for the fineness and number of layers of the mesh are similar.

Correction of small material flow rate can be done by measuring the return flow rate of the small material, or by dividing the total usage by the foaming time for correction. When the values obtained from the two correction methods differ significantly, the data from the second correction method should be used.

Formulas for soft foam with better properties are usually in an unstable range, such as lower TDI index, lower water to MC ratio, lower T-9 dosage, and lower silicone oil dosage. Just like in our jobs, there must be effort before reward.

Polyurethane flexible foam, also known as sponge, usually undergoes a liquid-to-solid transformation process within two minutes. Compared to other fields of polyurethane, the short and intense reaction time of flexible foam increases the difficulty in achieving fine and orderly cell structure, as well as molecular arrangement.



Research and development (R&D) involve introducing new materials to give products new properties. New materials can be categorized into two types based on their reaction characteristics: one type consists of raw materials that conform to the chemical reactions of polyurethane, such as polyether, isocyanate, silicone oil, and catalysts with different properties and activities. These materials do not fundamentally disrupt the chemical reaction process. The other type includes raw materials (fillers) that do not conform to the chemical reactions of polyurethane, such as adding non-foaming substances like special metal powders, specially formulated inorganic or organic powders with unique properties, ultrafine inorganic powders (with a fineness of over 5000 mesh), special antibacterial agents, etc. These materials sometimes completely disrupt the reaction process, leading to new reaction patterns. Some fillers cause the original formula to collapse completely, while others cause a significant change in the density of the finished product by 30% to 50%. Some fillers drastically alter the rise time of the reaction in the formula, and some fillers cause severe damage to the foam structure after being added.



R&D usually keeps certain raw materials on hand to deal with common problems encountered during the process. These raw materials typically require a wide range of physical and chemical properties. For example, amines such as A33, A-1, A-210, A-230, A-260, 33-LV, CS-90, 9717, and 9727 are commonly used in production but may not all be kept on hand for R&D purposes because their reactivity does not have a fundamental difference. In extensive R&D, the above-mentioned amines can be classified as materials in the same category. For instance, if adding a particular substance causes significant collapse when using A33 for foaming, then the remaining eight types of amines might be deemed ineffective.



One common issue encountered in R&D is foam collapse, which is the least efficient result. It is often said that analyzing and adjusting can only be done effectively once the foam structure is stable. Many cases of foam collapse cannot be resolved by adjusting the formula alone; either the foam properties change drastically, rendering it impractical, or the foam remains unstable. To address this, crosslinking agents are introduced. Crosslinking agents, commonly used as additives in R&D, generally come in two types: linear structured agents, where 1,4-butanediol represents the raw material and urea formation occurs through linear chain growth, and bulk structured agents, such as diethanolamine and glycerol, which are closer to polyether chain growth patterns.



For example, in one R&D case, adjusting the formula could not prevent foam collapse. Experience revealed that strong amine activity caused imbalance. The amine content was reduced from 0.2 parts per hundred polyether to 0.05 parts, and the high cyanate content in the formula seemed odd. The overall reaction rate also slowed significantly with the reduction in amine content, but the collapse persisted. Later, switching to a weaker amine resolved the issue. Hence, sometimes the activity of an amine cannot be compensated for by its concentration alone. It should be noted that the addition of certain substances may result in significant differences in performance between small-scale and large-scale foam production. In such cases, the performance of the last large-scale foam produced should be the main reference point for adjustment.



Sunlight, air, and water—the most ordinary and often overlooked things—are the most precious. Mastering foam production, which seems simple and lacking content at first glance, is actually quite challenging. As a colleague in R&D often says, "I have too little knowledge (one regrets having too little knowledge when it's needed)" and "How long will we keep doing this? (There's pressure)." R&D and learning foam production involve using known points to understand unknown areas, while production and teaching foam production involve using known areas to operate unknown points. Although these two aspects seem similar, bridging the gap between them is quite difficult.