Do you know what are the main raw materials of polyurethane foam?
Hyundai Motor Company's Ulsan plant will exclusively use BASF's Elastoflex polyurethane foam combination to manufacture car seats. This highly elastic polyurethane foam has a low VOC content and is mainly used in the production of car seats and headrests.
Compared to traditional foams, Elastoflex improves comfort, elasticity and load-bearing properties of seats and headrests, for example.
In order to meet the most stringent emission control regulations, BASF has also optimized the production process of polyether polyols. Polyether polyols are used in the production of Elastoflex polyurethane foam, which is used in the production of high-comfort seats. The optimized production process enables BASF to produce specialty polyether polyols with low cost, high performance and low VOC emissions.
In tests conducted by the world's leading testing agency SGSKorea, Elastoflex reduced acetaldehyde and formaldehyde emissions by more than 30%, helping to improve in-vehicle air quality and the health of car drivers. Field tests have also shown that the newly developed polyurethane composition has excellent flow properties and reduced product defect rates, resulting in improved production line productivity.
In the production of automobiles, car seats occupy a large area, which directly determines the number of materials used. Cars gradually affect people's way of life and make people's travel more and more convenient. Traditional car seats are mostly leather products, and most of them are made of sponge and other materials, which lack a certain degree of comfort. Nowadays, flexible polyurethane foam plastics As one of the production materials of car seats, it is of high quality and low price, and is gradually applied by manufacturers to a large number of car production.
Polyurethane foam is a kind of relatively soft new material with certain elasticity. It has many pores, density sole, good resilience, sound absorption, ventilation, and good thermal insulation properties. It is used in all aspects of life. Many manufacturers choose to use high-elasticity polyurethane foam as the material for car seats, and the performance of this material is gradually accepted by people.
The static comfort of a car seat refers to whether the matching relationship between the car seat and the human body can provide users with comfortable sitting conditions. The static comfort of the seat is related to the size parameters, surface treatment and adjustment characteristics of the seat.
The composition of car seats is mostly foam materials with high elasticity and low density, which can prevent the burning of substances. Today, the Chinese government has stricter requirements on automotive materials, requiring the maximum combustion value to be ≤70mm/min. Such regulations greatly increase the safety of the car itself, and the flexible polyurethane foam with this burning rate standard is used. Doing saddles is also gradually appearing in the field of vision of manufacturers.
The wear resistance of flexible polyurethane foam is used as the raw material of car seats. The fragility of many plastic products makes them unable to be used for a long time, but flexible polyurethane foam has good wear resistance. It has strong tensile strength and tear resistance, which makes it have superior performance. Compared with traditional car seats, it has low cost, long service time and strong plasticity. It can be applied to automobiles and gradually attract automobile production. favored by manufacturers.
With the development of the automobile industry, people have higher and higher requirements for its quality, especially safety, comfort and environmental protection have become the development trend of contemporary automobiles. QC/T 850-2011 "Polyurethane Foams for Passenger Car Seats" issued and implemented in 2011 is the first industry standard in my country that proposes emission requirements for polyurethane foams for car seats. Standard GB/T 7630-2011 "Guidelines for Air Quality Evaluation in Passenger Cars". This has prompted domestic assembly plants to put forward higher requirements for volatile organic compounds (VOC), mechanical properties and comfort properties of car seats.
Polyurethane flexible foam refers to a porous or reticulated foam (sponge) material with certain elasticity and softness. Its outstanding properties are softness, good rebound, sound absorption, ventilation, heat preservation, buffering, energy absorption, etc., and according to different There are also various characteristics of application areas.
Polyurethane flexible foam has been widely used in all aspects of people's daily life and many industrial fields since Bayer's polyester flexible foam (sponge) began industrial production in 1952. After more than 60 years of development, domestic flexible foam The actual production is estimated at more than 3 million tons. The main types of products are shockproof materials, sound insulation materials, filter materials, thermal insulation materials, packaging materials, decorative materials, clothing materials and so on. In terms of the type of production, flexible polyurethane foam mainly includes: block foam (ordinary sponge), high-resilience molded foam, self-skin foam, slow-rebound foam, etc.
Production Technology of Hydrophilic Polyurethane Flexible Foam
1. Basic Features
It has a great affinity for water, absorbs water quickly and has a large amount of water, high softness (good hand feel) and good elasticity; the microscopic cells are fine and have a reticular open-cell structure, and its excellent biological affinity and blood compatibility. It broadens its wide application in cosmetic and medical fields.
2. The current scope of application
The characteristics of hydrophilic polyurethane foam also determine that it will have a good application in some fields.
(1) Nursing and physiological products such as mattresses for bedridden patients and accessories for sanitary napkins
(2) Medical excipients, surgical excipients (absorbing blood is similar to cotton wool)
(3) Trauma dressing accessories, such as medical anti-inflammatory products such as Band-Aids, etc.
(4) Daily cleaning block, bath block, etc.
(5) Cosmetic care products, such as puffs, etc.
(6) Absorption treatment materials in special fields.
3. Production process
At present, there are two main process methods that have been industrialized or are being developed, one is a one-step method (same as the production method of ordinary PU foam), and the other is a two-step method, that is, the prepolymer method.
A typical two-step approach:
(1) Basic formula for prepolymer synthesis
Polyether polyol 0-100
Small molecule polyols 0-10
Catalyst 0.2-0.6
TDI 20-50 (non-yellowing can use HDI, IPDI, HMDI, etc.)
NCO% 3-14%
The production process of non-yellowing sponge flexible foam
At present, the bulk polyurethane flexible foams (sponges) are prone to yellowing. Now the anti-yellowing foam usually refers to the addition of antioxidants, heat stabilizers and light stabilizers during foam production, which can temporarily relieve The yellowing speed of the foam is easy to be turned yellow mainly because the benzene ring on the isocyanate can be gradually oxidized into a quinoid structure and turn yellow. In addition, the foam macromolecular chain contains carbonyl, amino, azo, alkenyl, etc. The chromophore, when light enters, will selectively absorb and emit light of a certain wavelength, resulting in a certain degree of yellowing of the flexible foam.
Effective solutions to tackle yellowing
The most effective way is to use non-yellowing aliphatic isocyanates for foaming. Aliphatic isocyanates, such as IPDI, HDI and HMDI, etc., the urethane bonds formed by these isocyanates are relatively stable. Aliphatic amine also has no benzene ring conjugated structure, and does not form an auxiliary color group, and aliphatic amine itself is not easy to be oxidized, and it is not easy to cause yellowing; therefore, the selection of aliphatic isocyanate can significantly reduce the yellowing of foam.
Technical Difficulties of Aliphatic Isocyanate Foaming
In fact, many people have tried foaming production in this area over the years, but most of them have encountered some technical difficulties more or less, that is, aliphatic isocyanates generally have low activity, and the foaming process is difficult to control and operate. The range or latitude is very narrow, and it is difficult to make flexible foam that meets the requirements. The problems that often occur in the foaming process are: collapsed or partially collapsed foam, coarse foam, surface powder or closed cells, and more serious blockages. Bubbles shrink.
What needs to be explained here is that the foam sponge foamed with aliphatic isocyanate does not actually turn yellow at all, but will oxidize and turn yellow very slowly under long-term light, water and heat conditions. The rate of yellowing of this type of foam is very low, and it seems to people that it does not turn yellow.
Foaming process
Different people or regions may have different foaming process methods, mainly due to different formulations, catalyst selection and dosage. This method is not the only one and is for reference only.
The highly active polyether and other additives are pre-mixed at room temperature, and then poured into IPDI and stirred for 6-15 seconds, and then poured into a pre-heated foaming box. - After 30 minutes, push the block out and ripen at room temperature for 24 hours before cutting. The cells are uniform and fine, with high strength, good elasticity, no pulverization, and generally no shrinkage. When a small amount of shrinkage occurs, you need to press lightly. Special caution is required not to use grafted polyether polyols.
Production process of microcellular flexible foam material
1. Application of microporous soft foam
It should be noted here that microcellular foam does not refer to microcellular PU elastomers (such as soles, insoles, high-speed rail gaskets, tires, car springs, etc.), but a soft high-density polyurethane foam sheet. It belongs to special polyurethane soft foam. This polyurethane flexible foam sheet has been widely used in communications, computers, household appliances, digital products, other electronic products, shoe materials, medical equipment, hardware, etc. as sealing, shock absorption, and cushioning materials.
2. Outstanding performance
High sealing, high energy absorption (high cushioning), high dimensional stability. Excellent compression deformation resistance, water resistance, high temperature resistance, aging resistance, environmental protection and no pollution, etc.
3. Basic molding process
This foaming process is different from the ordinary water-based chemical foaming or ordinary physical foaming agent (such as dichloromethane, etc.) foaming process, but adopts the permanent gas injection foaming method, and the basic production process adopts multi-component low-pressure foaming process. It is mechanically poured on the release paper of the conveyor belt and continuously scraped to a uniform thickness and then cured by a constant temperature gel in a drying tunnel. The product is rolled into a roll and then post-cured; the unique foaming process determines the outstanding performance of the material.
Technical focus:
Organometallic salt catalysts are suitable to control the reaction rate.
Strict temperature control is also an important factor in controlling product quality.
As one of the six major synthetic materials in the world, the polyurethane industry has expanded rapidly in recent years. According to the "2016-2022 China Polyurethane Industry Market Trend Forecast and Trend Forecast Research Report" released by Booz Data: the global output of polyurethane products has exceeded 21 million tons, of which foam system and non-foam system products each account for half of the country, and its huge growth potential is prepared for attention.
The trend of production scale is obvious In production, the polyurethane industry, like most chemical industries, has an increasingly obvious trend of intensification and scale. As polyurethane production technology becomes more and more mature, products become more popular and application fields continue to expand, manufacturers find that in order to maintain a certain level of profitability, they must have certain economies of scale. As a result, the scale of new enterprises is getting bigger and bigger, and the production capacity is also increasing rapidly.
