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.

Surfactants used for foam stabilization, also known as foam stabilizers, are a crucial additive in the production of polyurethane foam plastics. When selecting surfactants, what factors should be considered?



Surfactants can be divided into two types: soft foam surfactants and hard foam surfactants. Let's examine each:



Soft Foam Surfactants:

During the initial foaming stage, soft foam surfactants can dissolve to form polyurea, and in the later stages, they can assist in cell opening and bursting. Therefore, when selecting soft foam surfactants, the following factors need to be considered:



1. The activity of the surfactant;

2. The relationship between the operating range of the surfactant and the required dosage range;

3. The impact of the various components of the surfactant on the operating range.



Hard Foam Surfactants:

Hard foam surfactants have a higher degree of cross-linking, making bubbles more stable. They are commonly used for molded products or foaming in restricted cavities. When selecting hard foam surfactants, the following factors need to be considered:



1. Strong emulsification capability of the raw material components;

2. Ability to control the size of the foam cells effectively;

3. Ability to improve material flowability and ensure uniform density distribution.



Surfactants not only play a role in foam stabilization but also affect foam density, elasticity, tensile strength, and other properties. Therefore, when choosing surfactants, factors such as the activity of the raw materials, operating conditions, and foaming process need to be considered.

The amount of foam stabilizer determines the size of the foam structure's cells. More stabilizer leads to finer cells, but too much can cause shrinkage. Finding the right balance is crucial; too little stabilizer and the cells won't support each other, resulting in collapse during forming. Both are catalysts in action.

Polyurethane (Soft Foam) refers to a type of flexible polyurethane foam plastic with a certain elasticity, mostly having open-cell structures.

Polyurethane (Hard Foam) refers to foam plastics that do not undergo significant deformation under certain loads and cannot recover to their initial state after excessive loads. Mostly closed-cell.



Hard Foam Silicone Oil

Hard foam silicone oil is a type of highly active non-hydrolyzable foam stabilizer with a silicon-carbon bond, belonging to a broad-spectrum silicone oil category. It has excellent comprehensive performance and is suitable for HCFC-141b and water foaming systems, used in applications such as boards, solar energy, pipelines, etc.



Product Features:

1. Good emulsification performance: The excellent emulsification performance allows for good dispersion and mixing of the composite materials during the reaction with isocyanate, resulting in good flowability. The produced product has uniform cells and a very high closed-cell rate.

2. Good stability: The special molecular structure effectively controls the surface tension of the cells, stabilizing the cell structure and providing the product with excellent mechanical properties.



Soft Foam Silicone Oil:

A general-purpose siloxane surfactant for polyether-type flexible polyurethane foam plastics, it is a non-hydrolyzable polydimethylsiloxane-polyethylene copolymer, a high-activity stabilizer. It is used as a foam stabilizer in the production of polyurethane soft foam (sponge). It can provide a thin skin. In very low-density foam, it provides strong stability with fine and uniform cells. In medium-depth foam, compared to similar silicone oils, it has better foam opening properties and breathability.

What is Polyurethane Rigid Foam?



Polyurethane rigid foam, often abbreviated as PU rigid foam, is one of the most commonly used polyurethane products, second only to polyurethane soft foam, in polyurethane applications. Polyurethane rigid foam is mostly a closed-cell structure, known for its excellent insulation, lightweight, high strength-to-weight ratio, ease of construction, as well as soundproofing, shock absorption, electrical insulation, heat resistance, cold resistance, solvent resistance, and more. It is widely used in the insulation layers of refrigerator and freezer boxes, cold storage rooms, refrigerated trucks, as well as insulation materials for buildings, tanks, and pipelines. A small amount is used in non-insulation applications such as wood imitation and packaging materials. Generally, lower-density polyurethane rigid foam is primarily used as thermal insulation material, while higher-density polyurethane rigid foam can be used as structural material (wood imitation).



Polyurethane rigid foam is typically foamed at room temperature, with a relatively simple molding process. It can be categorized into manual foaming and mechanical foaming based on the degree of construction mechanization; high-pressure foaming and low-pressure foaming based on the foaming pressure; and casting foaming and spraying foaming based on the molding method.



What is Polyurethane Soft Foam?



Polyurethane soft foam, also known as PU soft foam, is a type of flexible polyurethane foam with a certain degree of elasticity. It is the most extensively used polyurethane product among all polyurethane products.



Polyurethane soft foam is mostly an open-cell structure, characterized by low density, good elastic recovery, sound absorption, breathability, and insulation properties. It is primarily used as cushioning materials for furniture, mattresses, vehicle seat cushions, and also finds industrial and domestic applications as filter materials, soundproofing materials, shock absorption materials, decorative materials, packaging materials, and insulation materials. Based on the degree of softness and load-bearing capacity, polyurethane soft foam can be divided into ordinary soft foam, super soft foam, high load-bearing soft foam, high resilience soft foam, etc. High resilience and high load-bearing soft foams are generally used for manufacturing seat cushions and mattresses. According to the production process, polyurethane soft foam can be divided into block foam and molded foam. Block foam is produced by continuous process to form large volume foam which is then cut into required shapes, while molded foam is produced by direct injection of the mixture into molds to form foam products of desired shapes.



After understanding polyurethane rigid foam and polyurethane soft foam, the question arises: how do we differentiate between the two?



In fact, the classification can be based on the degree of hardness, dividing them into soft foam plastics and hard plastics. Soft foam plastics have a matrix polymer component above the crystalline melting point, or, if it is an amorphous polymer, it is above the glass transition temperature; hard foam, on the other hand, has its matrix polymer in a crystalline state or an amorphous state but below the glass transition temperature. Semi-rigid foam is a foam plastic between soft and hard foam. It is similar to soft foam, with an open cell rate above 90℃, but semi-rigid foam has higher density and higher compression strength. After compression deformation, semi-rigid foam takes much longer to recover, and its crosslinking density is much higher than soft foam but lower than hard foam.



Based on this classification of softness and hardness, most polyolefin foams, unplasticized polyvinyl chloride (PVC) foams, phenolic foams, polycarbonate foams, and polyphenylene ether foams are all classified as hard foams, while elastic polyurethane foams and some polyolefin foams and plasticized PVC foams are classified as soft foams.



According to the national standard, soft foam plastics are those that are flexible, have low compression hardness, return to their original state after stress is relieved, and have minimal residual deformation. On the other hand, hard foam plastics are inflexible, have high compression hardness, deform when stress reaches a certain level, and do not return to their original state after stress is relieved.



The American Society for Testing and Materials (ASTM) specifies that to differentiate between soft and hard foam plastics, at a temperature of 18-29℃, a rod with a diameter of 2.5 cm is rotated around it for one full rotation within 5 seconds. If it does not fracture, it is classified as soft foam plastic; otherwise, it is classified as hard foam plastic.



According to ISO standards, when the compression deformation reaches 50% and is then released, if the thickness decreases by no more than 2% compared to the original thickness, it is classified as soft foam plastic. If it decreases by more than 10%, it is classified as hard foam plastic. If the decrease is between 2-10%, it is classified as semi-rigid foam plastic.



If we use elastic modulus as the criterion, in a standard environment of 23℃ and 50% relative humidity, a foam plastic with an elastic modulus greater than 686 MPa is classified as hard foam, less than 68.6 MPa is classified as soft foam, and between 68.6-686 MPa is classified as semi-rigid foam. Although the elastic modulus of semi-rigid foam is higher than that of soft foam, its stress-strain behavior is closer to soft foam and significantly different from hard foam. Generally, soft foam plastics mostly have an open-cell structure, while hard foam plastics mostly have a closed-cell structure, but there are exceptions.