End-to-end solutions from raw materials to production equipments for PU foam and mattress.
Polyurethane Foam Machine Buying Guide
Sabtech Technology Limited aims to provide global customers with innovative and practical products, such as polyurethane foam machine. We have always attached great importance to product R&D since establishment and have poured into a tremendous investment, both time and money. We have introduced advanced technologies and equipment as well as first-class designers and technicians with which we are highly capable of creating a product that can effectively solve customers' needs.
We seek to establish long-term business relationships with clients and partners, as evidenced by the repeat business from existing clients. We work collaboratively and transparently with them, which allows us to resolve issues more effectively and to deliver exactly what they want, and further to build a large customer base for our Sabtech brand.
At Sabtech Technology Limited, we offer solutions of polyurethane foam machine and suchlike products that can be tailored to the needs of our existing and future partners and customers in any given market. Get the questions answered about product specifications, use and care at the product page.
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In December 2021, we received an inquiry from Mr. Hairun in Malaysia. Mr. Hairun is a mattress manufacturer in need of producing rebonded foam. He had limited knowledge about machine usage and selection and had no prior experience with the production process. Therefore, he required guidance from experts who could assist him from the ground up.
We systematically explained the principles of foam production to Mr. Hairun, along with the necessary materials and equipment. We also took him on a tour of our factory to provide a clear understanding of the entire production process.
After understanding Mr. Hairun's preferences for the rebonded foam, including density, softness, and market prices, we offered him the most suitable foam production solution. We also provided him with information on foam production costs and compared raw material prices for his reference.
Based on the client's needs, budget, and existing factory layout, we devised a cost-effective machine configuration and layout plan for his facility, including an assessment of startup costs.
Once the machines were successfully installed, our team of engineers provided Mr. Hairun with one-on-one foam production training. When he successfully produced the foam he desired for the first time, he called us and said, "I am happy with crying, thank you very much!" Afterward, he purchased a batch foam machine from us and continued to reorder foam chemical materials from our company.
We systematically explained the principles of foam production to Mr. Hairun, along with the necessary materials and equipment. We also took him on a tour of our factory to provide a clear understanding of the entire production process.
After understanding Mr. Hairun's preferences for the rebonded foam, including density, softness, and market prices, we offered him the most suitable foam production solution. We also provided him with information on foam production costs and compared raw material prices for his reference.
Based on the client's needs, budget, and existing factory layout, we devised a cost-effective machine configuration and layout plan for his facility, including an assessment of startup costs.
Once the machines were successfully installed, our team of engineers provided Mr. Hairun with one-on-one foam production training. When he successfully produced the foam he desired for the first time, he called us and said, "I am happy with crying, thank you very much!" Afterward, he purchased a batch foam machine from us and continued to reorder foam chemical materials from our company.
Many factors affect the foaming process and final product quality when manufacturing polyurethane flexible foam. Among these, natural environmental factors such as temperature, air humidity, and atmospheric pressure play crucial roles. These factors significantly influence foam density, hardness, elongation rate, and mechanical strength.
1. Temperature:
Polyurethane foaming reaction is highly sensitive, with temperature being a key control factor. As material temperature rises, the foaming reaction accelerates. In sensitive formulations, excessively high temperatures can pose risks like core burning and ignition. Generally, it's essential to maintain consistent temperatures for polyol and isocyanate components. Increasing temperature leads to a corresponding decrease in foam density during foaming.
Particularly in summer, elevated temperatures increase reaction speed, resulting in decreased foam density and hardness, increased elongation rate, yet enhanced mechanical strength. To counter hardness reduction, adjusting the TDI index is advisable. Manufacturers must adjust process parameters according to seasonal and regional temperature variations to ensure product quality stability.
2. Air Humidity:
Air humidity also affects the foaming process of polyurethane flexible foam. Higher humidity causes reactions between isocyanate groups in the foam and airborne moisture, leading to reduced product hardness. Increasing TDI dosage during foaming can compensate for this effect. However, excessive humidity can raise curing temperatures, potentially causing core burning. Manufacturers need to carefully adjust foam process formulations and parameters in humid environments to ensure product quality and stability.
3. Atmospheric Pressure:
Atmospheric pressure is another influencing factor, especially in areas at different altitudes. Using the same formulation at higher altitudes results in relatively lower foam product density. This is due to atmospheric pressure variations affecting gas diffusion and expansion during foaming. Manufacturers operating in high-altitude regions should take note of this and may need to adjust formulations or process parameters to meet quality requirements.
In conclusion, natural environmental factors significantly impact the foaming process and final product quality of polyurethane flexible foam. Manufacturers must adjust process parameters based on seasonal, regional, and environmental conditions to ensure stable foam density, hardness, and mechanical strength, meeting customer demands and standards.
1. Temperature:
Polyurethane foaming reaction is highly sensitive, with temperature being a key control factor. As material temperature rises, the foaming reaction accelerates. In sensitive formulations, excessively high temperatures can pose risks like core burning and ignition. Generally, it's essential to maintain consistent temperatures for polyol and isocyanate components. Increasing temperature leads to a corresponding decrease in foam density during foaming.
Particularly in summer, elevated temperatures increase reaction speed, resulting in decreased foam density and hardness, increased elongation rate, yet enhanced mechanical strength. To counter hardness reduction, adjusting the TDI index is advisable. Manufacturers must adjust process parameters according to seasonal and regional temperature variations to ensure product quality stability.
2. Air Humidity:
Air humidity also affects the foaming process of polyurethane flexible foam. Higher humidity causes reactions between isocyanate groups in the foam and airborne moisture, leading to reduced product hardness. Increasing TDI dosage during foaming can compensate for this effect. However, excessive humidity can raise curing temperatures, potentially causing core burning. Manufacturers need to carefully adjust foam process formulations and parameters in humid environments to ensure product quality and stability.
3. Atmospheric Pressure:
Atmospheric pressure is another influencing factor, especially in areas at different altitudes. Using the same formulation at higher altitudes results in relatively lower foam product density. This is due to atmospheric pressure variations affecting gas diffusion and expansion during foaming. Manufacturers operating in high-altitude regions should take note of this and may need to adjust formulations or process parameters to meet quality requirements.
In conclusion, natural environmental factors significantly impact the foaming process and final product quality of polyurethane flexible foam. Manufacturers must adjust process parameters based on seasonal, regional, and environmental conditions to ensure stable foam density, hardness, and mechanical strength, meeting customer demands and standards.
14. Poor Rebound
A. Raw materials: high activity polyether polyols, low molecular weight, highly active silicone oil.
B. Process formulation: high silicone oil content, excessive tin, high water content with the same tin usage, high TDI index, large amount of white oil and powder.
15. Poor Tensile Strength
A. Raw materials: excessive low molecular weight polyether polyols, low functionality hydroxyl value.
B. Process formulation: insufficient tin, poor gelation reaction, high TDI index with the same tin usage, low water content, low crosslinking.
16. Smoke during Foaming
Excessive amine release a large amount of heat during water and TDI reaction, causing evaporation of low-boiling substances and smoke. If not core scorching, smoke mostly consists of TDI, low-boiling substances, and monomer cycloalkanes in polyether polyols.
17. Foam with White Streaks
Fast foaming and gelation reaction but slow transfer in continuous foaming, resulting in a dense layer due to localized compression, causing white streaks. Increase transfer speed or lower material temperature, reduce catalyst usage.
18. Brittle Foam
Excessive water in the formulation leads to excess biuret formation, which does not dissolve in silicone oil. Poor use of tin catalyst, insufficient cross-linking reaction, high content of low molecular weight polyether polyols, high reaction temperature causing ether bond breakage and decreased foam strength.
19. Foam Density Lower than Set Value
Foam index is too high due to inaccurate measurement, high temperature, low pressure.
20. Foaming with Skin, Edge Skin, and Bottom Air
Excessive tin, insufficient amine, slow foaming rate, fast gelation rate, low temperature during continuous foaming.
21. Elongation Rate Too High
A. Raw materials: high activity polyether polyols, low functionality.
B. Process formulation: low TDI index, insufficient cross-linking, high tin.
22. Uncontrolled Foam (Small bubbles rapidly moving beneath surface)
A. Low-pressure foaming machine: increase mixing head speed, decrease gas injection.
B. High-pressure foaming machine: increase mixing head pressure.
23.Milky Moving Lines
A. Increase conveyor speed
B. Adjust cushion plate inclination.
C. Reduce amine catalyst usage
24.Inserted Material Backflow
A. Increase conveyor speed.
B. Adjust cushion plate inclination.
C. Increase amine catalyst usage.
25.Moon Pits
A. Low-pressure foaming machine: reduce mixing head speed and gas injection.
B. High-pressure foaming machine: increase mixing head pressure.
C. Silicone oil quality issue.
D. Increase amine amount while reducing tin amount to ensure adequate cell opening.
26.Slow Curing,Sticky Surface
Polymer strength increases too slowly, resulting in soft, sticky foam that is difficult to cut.
Foam blocks appear unstable when exiting channels.
Increase catalyst usage, check polyol, water, and TDl measurement accuracy.
A. Raw materials: high activity polyether polyols, low molecular weight, highly active silicone oil.
B. Process formulation: high silicone oil content, excessive tin, high water content with the same tin usage, high TDI index, large amount of white oil and powder.
15. Poor Tensile Strength
A. Raw materials: excessive low molecular weight polyether polyols, low functionality hydroxyl value.
B. Process formulation: insufficient tin, poor gelation reaction, high TDI index with the same tin usage, low water content, low crosslinking.
16. Smoke during Foaming
Excessive amine release a large amount of heat during water and TDI reaction, causing evaporation of low-boiling substances and smoke. If not core scorching, smoke mostly consists of TDI, low-boiling substances, and monomer cycloalkanes in polyether polyols.
17. Foam with White Streaks
Fast foaming and gelation reaction but slow transfer in continuous foaming, resulting in a dense layer due to localized compression, causing white streaks. Increase transfer speed or lower material temperature, reduce catalyst usage.
18. Brittle Foam
Excessive water in the formulation leads to excess biuret formation, which does not dissolve in silicone oil. Poor use of tin catalyst, insufficient cross-linking reaction, high content of low molecular weight polyether polyols, high reaction temperature causing ether bond breakage and decreased foam strength.
19. Foam Density Lower than Set Value
Foam index is too high due to inaccurate measurement, high temperature, low pressure.
20. Foaming with Skin, Edge Skin, and Bottom Air
Excessive tin, insufficient amine, slow foaming rate, fast gelation rate, low temperature during continuous foaming.
21. Elongation Rate Too High
A. Raw materials: high activity polyether polyols, low functionality.
B. Process formulation: low TDI index, insufficient cross-linking, high tin.
22. Uncontrolled Foam (Small bubbles rapidly moving beneath surface)
A. Low-pressure foaming machine: increase mixing head speed, decrease gas injection.
B. High-pressure foaming machine: increase mixing head pressure.
23.Milky Moving Lines
A. Increase conveyor speed
B. Adjust cushion plate inclination.
C. Reduce amine catalyst usage
24.Inserted Material Backflow
A. Increase conveyor speed.
B. Adjust cushion plate inclination.
C. Increase amine catalyst usage.
25.Moon Pits
A. Low-pressure foaming machine: reduce mixing head speed and gas injection.
B. High-pressure foaming machine: increase mixing head pressure.
C. Silicone oil quality issue.
D. Increase amine amount while reducing tin amount to ensure adequate cell opening.
26.Slow Curing,Sticky Surface
Polymer strength increases too slowly, resulting in soft, sticky foam that is difficult to cut.
Foam blocks appear unstable when exiting channels.
Increase catalyst usage, check polyol, water, and TDl measurement accuracy.
Functionality: Refers to the number of special groups (and reactivity) in the structure of an organic compound. For polyether or polyester polyols, functionality refers to the number of atoms containing active hydrogen.
Hydroxyl Value (OHV): From an analytical perspective, the hydroxyl value is defined as the milligrams of potassium hydroxide equivalent to the hydroxyl value in 1 gram of the sample. The weight percentage of hydroxyl value is represented as OH%. OHV = Weight percentage of hydroxyl value * 33.
Molecular Weight: The molecular weight refers to the relative weight of a single substance or compound molecule, equal to the sum of the atomic weights of the atoms in the molecule.
Molecular Weight = 56.1*Functionality *1000 / Hydroxyl Value
56.1 is the molecular weight of potassium hydroxide. For simple compounds, the molecular weight is the sum of the atomic weights of the atoms in the molecule.
Isocyanate Group Percentage Content: The isocyanate group percentage content is typically expressed as NCO%. For pure TDI/MDI, it can be calculated using the molecular formula:
NCO% for TDI = 42 * 2 / 174 = 48%
NCO% for MDI = 42 * 2 / 250 = 33.6%
42 is the molecular weight of NCO.
Sometimes NCO% is also represented using amine equivalents: the number of grams of isocyanate ester consumed per gram of molecule amine to form the corresponding urea.
Amine Equivalent and NCO% are related as follows:
Amine Equivalent = 4200 / NCO%
Equivalent Value and Equivalent Number: Equivalent value refers to the molecular weight corresponding to one unit functionality in each compound molecule.
Equivalent Value = Number average molecular weight / Functionality
For polyester and polyether products, the equivalent value is calculated directly from the hydroxyl value data.
Equivalent Value = 56100 / Hydroxyl Value
TDI Equivalent = Number average molecular weight / Functionality
= 174 / 2 = 87
= 42.02 * 100 / NCO%
Hydroxyl Value (OHV): From an analytical perspective, the hydroxyl value is defined as the milligrams of potassium hydroxide equivalent to the hydroxyl value in 1 gram of the sample. The weight percentage of hydroxyl value is represented as OH%. OHV = Weight percentage of hydroxyl value * 33.
Molecular Weight: The molecular weight refers to the relative weight of a single substance or compound molecule, equal to the sum of the atomic weights of the atoms in the molecule.
Molecular Weight = 56.1*Functionality *1000 / Hydroxyl Value
56.1 is the molecular weight of potassium hydroxide. For simple compounds, the molecular weight is the sum of the atomic weights of the atoms in the molecule.
Isocyanate Group Percentage Content: The isocyanate group percentage content is typically expressed as NCO%. For pure TDI/MDI, it can be calculated using the molecular formula:
NCO% for TDI = 42 * 2 / 174 = 48%
NCO% for MDI = 42 * 2 / 250 = 33.6%
42 is the molecular weight of NCO.
Sometimes NCO% is also represented using amine equivalents: the number of grams of isocyanate ester consumed per gram of molecule amine to form the corresponding urea.
Amine Equivalent and NCO% are related as follows:
Amine Equivalent = 4200 / NCO%
Equivalent Value and Equivalent Number: Equivalent value refers to the molecular weight corresponding to one unit functionality in each compound molecule.
Equivalent Value = Number average molecular weight / Functionality
For polyester and polyether products, the equivalent value is calculated directly from the hydroxyl value data.
Equivalent Value = 56100 / Hydroxyl Value
TDI Equivalent = Number average molecular weight / Functionality
= 174 / 2 = 87
= 42.02 * 100 / NCO%
Chemical change is the process of producing new substances after the molecular groups of various reactants interact with each other. Many properties of substances are determined by their molecular structures, and understanding the molecular and group structures in polyurethane reactants is instructive for production.
The main indicators of British standard flame retardancy are generally threefold: thermal weight loss (the mass lost when the specified size of sponge is heated at a specified temperature for a specified time, with smaller values indicating better thermal stability); smoke density (the amount of smoke generated when the foam burns, indicating the ease of light passing through the smoke, with smaller amounts of smoke being better); and ease of combustion (the more difficult it is to ignite, with further subdivisions based on ignition time and burning rate).
TDI (toluene diisocyanate) has one benzene ring, MDI (diphenylmethane diisocyanate) has two benzene rings, and crude MDI has multiple benzene rings. Benzene rings are very stable substances, requiring a large amount of energy (bond dissociation energy) to break. As the number of benzene rings increases, the thermal stability of the foam increases (crude MDI > MDI > TDI), making it less likely to decompose when heated. With more benzene rings, there are more carbon atoms in the molecule, resulting in more smoke when incompletely burned (crude MDI > MDI > TDI). From the above, it can be concluded that when one formula decreases the amount of TDI and increases the amount of MDI, the thermal stability of the foam will be enhanced. The thermal weight loss index is likely to pass the British standard test, but the smoke density, which is not easy to pass, will increase. At this point, it is advisable to appropriately increase the amount of melamine cyanurate to reduce smoke density.
The higher the molecular weight of the polyether, the worse the thermal stability, but the better the fire resistance. In the production of high-rebound flame-retardant foam, the amount of flame retardant added is only two-thirds that of regular-density flame-retardant foam, yet the flame retardancy remains very good and does not ignite. However, high-rebound flame-retardant foam is more difficult to pass the British standard test than regular foam (thermal weight loss is difficult to pass).
Flame retardants are not very stable when heated. Since the British standard test emphasizes thermal weight loss, the amount of flame retardant in the formula is the minimum required to pass the flame retardancy test.
When both TDI and water content in the formula decrease while methane content increases, the foam is less likely to ignite. The decrease in intrinsic properties due to the reduction of hard segments results in decreased thermal stability, thus reducing the ability to pass the thermal weight loss index.
When the foam density decreases, the TDI content increases, and both smoke density and thermal stability increase.
Inorganic materials like calcium carbonate and barium sulfate do not decompose when heated during British standard tests, but their addition does not improve the foam's properties, so they are not used in the British standard formula.
Besides selecting raw materials, achieving a balance is also crucial when meeting British standards. For example, both TDI and flame retardants, if given too much or too little, make it difficult to pass the test. Foaming is a balanced science, adjusting the formula is about seeking balance, and selecting raw materials is also about seeking balance.
The main indicators of British standard flame retardancy are generally threefold: thermal weight loss (the mass lost when the specified size of sponge is heated at a specified temperature for a specified time, with smaller values indicating better thermal stability); smoke density (the amount of smoke generated when the foam burns, indicating the ease of light passing through the smoke, with smaller amounts of smoke being better); and ease of combustion (the more difficult it is to ignite, with further subdivisions based on ignition time and burning rate).
TDI (toluene diisocyanate) has one benzene ring, MDI (diphenylmethane diisocyanate) has two benzene rings, and crude MDI has multiple benzene rings. Benzene rings are very stable substances, requiring a large amount of energy (bond dissociation energy) to break. As the number of benzene rings increases, the thermal stability of the foam increases (crude MDI > MDI > TDI), making it less likely to decompose when heated. With more benzene rings, there are more carbon atoms in the molecule, resulting in more smoke when incompletely burned (crude MDI > MDI > TDI). From the above, it can be concluded that when one formula decreases the amount of TDI and increases the amount of MDI, the thermal stability of the foam will be enhanced. The thermal weight loss index is likely to pass the British standard test, but the smoke density, which is not easy to pass, will increase. At this point, it is advisable to appropriately increase the amount of melamine cyanurate to reduce smoke density.
The higher the molecular weight of the polyether, the worse the thermal stability, but the better the fire resistance. In the production of high-rebound flame-retardant foam, the amount of flame retardant added is only two-thirds that of regular-density flame-retardant foam, yet the flame retardancy remains very good and does not ignite. However, high-rebound flame-retardant foam is more difficult to pass the British standard test than regular foam (thermal weight loss is difficult to pass).
Flame retardants are not very stable when heated. Since the British standard test emphasizes thermal weight loss, the amount of flame retardant in the formula is the minimum required to pass the flame retardancy test.
When both TDI and water content in the formula decrease while methane content increases, the foam is less likely to ignite. The decrease in intrinsic properties due to the reduction of hard segments results in decreased thermal stability, thus reducing the ability to pass the thermal weight loss index.
When the foam density decreases, the TDI content increases, and both smoke density and thermal stability increase.
Inorganic materials like calcium carbonate and barium sulfate do not decompose when heated during British standard tests, but their addition does not improve the foam's properties, so they are not used in the British standard formula.
Besides selecting raw materials, achieving a balance is also crucial when meeting British standards. For example, both TDI and flame retardants, if given too much or too little, make it difficult to pass the test. Foaming is a balanced science, adjusting the formula is about seeking balance, and selecting raw materials is also about seeking balance.
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we welcome custom designs and ideas and is able to cater to the specific requirements. for more information, please visit the website or contact us directly with questions or inquiries.
Over 20 years of first-hand production and usage experience, our technology development team aims to make every machine exhibit the characteristics of simplicity, labor efficiency, ease of operation, and minimal maintenance.
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Contact Person: Wenky Lau
Contact Number: +86-15687268672
Email: sales1@alforu.cn
WhatsApp: +86 15687268672
Company Address: NO. 18 South Industry Road, Dongguan City, Guangdong Province China
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