Specialty additives for polyurethane flexible foam
Polyurethane soft foam is a flexible polyurethane foam with a certain degree of elasticity, commonly known as polyurethane sponge, foam. This kind of foam is elastic, generally with low density, good elastic response, sound absorption, breathable, heat preservation and other properties, mainly used in a variety of thermal materials, cushioning materials, such as cars, boats and furniture sofa seat cushions, cushions and armrests, mattresses, clothing padding and so on. Industrial and civil use of soft foam as filter materials, sound insulation materials, shockproof materials, decorative materials, packaging materials and thermal insulation materials.
Among them, the laminated composite material made of soft foam sheet and various textile fabrics is one of the classic application fields of soft foam. The composite sheet is lightweight, with good heat insulation and air permeability, especially suitable for use as clothing lining. For example, it is used as clothing shoulder pads, bra sponge pads, all kinds of shoes lining and handbag lining.
In addition, due to the PU soft foam air permeability and moisture permeability, but also suitable for the production of mattresses. For example, in our country called “Simmons” mattress, most by the PU soft foam sheet, spring and fabrics made. At the same time, because PU soft foam has good sound absorption and vibration damping performance, can also be used as sound insulation materials within the equipment.
It can be seen that the application of PU foam is everywhere, is an important material essential to life. Qingdao Deda Zhicheng Chemical Industry, as a professional supplier of special additives, has accumulated many years of experience in the field of polyurethane additives, and is able to provide customers with all kinds of solutions for polyurethane foam plastic modifiers.
As a new product developed for polyurethane flexible foam, as a new generation of phenol-free phosphite antioxidant, AN6133 does not contain phenol, nonylphenol, bisphenol A and other free phenolic substances. With the advantages of low volatility, good heat resistance and hydrolysis resistance, it can effectively improve the thermal stability and anti-smoke (NOX) yellowing performance of polyurethane foam. And it can be widely used in PVC, rubber, plastic, oil and other polymers.
At the same time, it is used in soft/hard PVC materials as efficient auxiliary stabilizer and chelating agent, which can effectively improve its processing thermal stability and light stability, and keep the color stability and transparency of the products. It is an efficient antioxidant for ABS, SBS, SIS, SEBS and other rubber materials.
Polyurethane soft foam is mostly open-cell structure, with low density, good elastic response, sound absorption, air permeability, heat preservation and other properties, mainly used as furniture cushions, mattresses, transportation seat cushions and other cushion materials, industrial and civil use of soft foam as filtration materials, sound insulation materials, shockproof materials, decorative materials, packaging materials and thermal insulation materials, and so on. At present, high resilience, slow resilience, self-skinning, high flame retardant foam will be more and more widely used in various fields.
Chemical blowing agents
There are many kinds of substances used as chemical blowing agents, according to the chemical structure, there are mainly N-nitroso compounds, such as N, N-dinitroso pentamethylene tetramine (DPT), N, N-dimethyl-N, N-diylidene-p-phenylene diamide (NTA), etc.; azole compounds, such as azodicarbonamide (ADC), azodiisobutyronitrile, azo dicarboxylic acid isopropyl ester, azo dicarboxylic acid diethyl ester, bis(azodiyl) aminobenzene, azodicarboxylic acid, bis(azodi) amine benzene, and azodicarboxylic acid. Aminobenzene, azodicarboxylic acid barium, etc.; hydrazide compounds, such as 4,4-disulfonylhydrazine diphenyl ether (OBSH), p-phenylsulfonylhydrazine, 3,3-disulfonylhydrazine diphenyl sulfone, 4,4-diphenyl di-sulfonyl hydrazine, 1,3-benzene-disulfonylhydrazine, 1,4-benzene-disulfonylhydrazine, and so on. The main varieties used are foaming agent ADC, DPT, DBSH, etc., of which ADC accounts for 90% of the chemical foaming agent in foreign countries and more than 95% in China.
(1) ADC blowing agent
China is the world’s largest producer and supplier of ADC, the annual production capacity of 150,000 tons, accounting for about 50% of the total global production, 1995 to 2003, the average annual growth rate of production capacity of about 18%, showing a rapid momentum of development. There are more than 30 manufacturers in 30 provinces and cities across the country, including Jiangsu Sopo Group, Zhejiang Juhua Group Company, Jiangxi Electrochemical Plant, Ningxia Electrochemical Plant, the annual production capacity of 10,000 tons of level; production equipment, there are many improvements, such as sodium hypochlorite production equipment, large-scale, continuous; condensation kettle, oxidation kettle large-scale; change to continuous drying process, and so on. Optimized the synthesis of hydrazine hydrate process, oxidation process control parameters, improve the yield of each process, the comprehensive utilization of by-products and so on. At present, the domestic ADC blowing agent consumption structure is; PVC accounts for about 40%, polyethylene 35%, polypropylene 12%, rubber 5%, other 8%. There are 5,000 to 6,000 tons of exports each year, the products are mainly exported to Southeast Asia, Japan, South Korea and Russia.
Although China’s ADC production capacity and process technology has made great progress, but still commonly used urea method of synthesizing hydrazine hydrate as raw material, resource waste and serious environmental pollution; while foreign countries mainly use ketone nitrogen method or hydrogen peroxide method of raw material production of ADC blowing agent. The most obvious gap is that the domestic production of ADC can only be pure products, only a very small number of manufacturers to develop and produce a limited number of varieties of modified ADC blowing agent, but the yield is not high, the performance is not stable, the application range is narrow.
With the development of the plastics industry, a single ADC blowing agent can no longer meet the demand, so modified ADC blowing agent came into being. Abundant modification methods lead to diversification of ADC varieties, specialization, serialization, modification research has become the key to the development of ADC, and ADC modification process is basically no three wastes, less investment, economic and social benefits can be considerable. In recent years, Shanghai Xiangyang Chemical Factory has produced a series of ADC modified products AC-K, used in PVC artificial leather, the process is easy to control, the bubble holes are fine; Juhua Group has also developed three kinds of modified products. However, compared with foreign countries there is still a big gap, foreign countries have developed hundreds of varieties, there are still a large number of patents reported each year, many new varieties continue to come out to dominate the market, while China is mainly ADC raw powder sales and exports, to provide primary raw materials for the developed countries, and therefore will be polluted to stay at home, will be given to the profits abroad, the industry lacks the strength to develop.
ADC product modification is to optimize the foaming agent’s gas generation, granularity, color, thermal decomposition temperature, the main ways are: in the preparation process to change certain reaction conditions or add certain additives; ADC particles micronized; add additives in the ADC powder; different types of blowing agents to achieve the modified effect of compounding.
At present, the main types of modified products are: (A) particle miniaturization type. At present, the domestic ADC particles coarse, fewer grades, foreign according to the different particle size has a variety of grades to adapt to the foaming needs of different synthetic materials. It is mainly used to crush and classify the raw powder of foaming agent. (B) low temperature type. Ordinary ADC decomposition temperature is generally higher than 200 ℃, many softening point of low and easy to heat aging of the resin hope to have a low-temperature decomposition type products.
At present, the development of low-temperature type ADC is one of the main research topics in the field of its modification. Mainly choose one or more activators, and ADC to a certain proportion of the combination of activators can choose chromium, zinc, lead and other metal compounds, urea derivatives and nitroguanidine, etc., after modification of the ADC foaming agent can reach a minimum decomposition temperature of 80 ℃. (C) high dispersibility type. To obtain a uniform non-porous polymer with smooth surface, it is required that the blowing agent can be completely dispersed in proportion within the polymer. Generally, ADC blowing agent is easily affected by static electricity and other factors, and agglomerates into clusters, which affects product quality. The development of highly dispersible products is very important, ADC blowing agent and some inert inorganic compounds can be mixed with fine powder, in addition to ADC products can be added to the surfactant and other highly dispersible products. (D) Foaming inhibition type. Binary carboxylic acid and its hydrazide, phenols, amines and triazoles and other substances can inhibit the decomposition of ADC, when there is a metal ionic activator its inhibition effect is better. If a person is added to inhibit the foaming type foaming agent material, it will cause uneven patterns due to the difference in foaming effect, and thus produce foamed wallpaper and other upholstery materials. (E) Composite type. Other additives with specific functions can be mixed with ADC, or several foaming agents can be mixed with each other and compounded into one according to the principle of synergistic effect between various additives. Composite additives have become the mainstream of the development of the plastic additives industry. (F) foaming agent masterbatch. With other synthetic materials additives development trend, masterbatch has become one of the modification trend of the foaming agent ADC. ADC, foaming additives, polymers for mixing to get masterbatch, effectively solving the problem of dispersion and dust pollution, etc., is not yet developed domestically. AMERICHEM is the world’s most famous foaming agent masterbatch producers, supplying a dedicated series of ADC products brand name SUPERCELL; U.S. HENLY launched EXOCEROL and other series of blowing agent, are For the masterbatch form, such as EXOCER01232 and LAB010 is a mixture of heat-absorbing and exothermic type, A038 is a mixture of several kinds of exothermic blowing agent. Therefore, the key to future ADC foaming agent is to learn from foreign experience, vigorously develop heat-absorbing, heat-absorbing / exothermic and high-temperature decomposition of foaming agent varieties, and through the masterbatch and surface modification to reduce the dust contamination of the foaming agent.
(2)Blowing agent OBSH
OBSH blowing agent chemical name for 4,4′-di-disulfonylhydrazine diphenyl ether, is commonly used in the plastics and rubber industry, low-temperature blowing agent, mainly by the diphenyl ether sulfonation and hydrazine hydrate reaction and obtained, the earliest by the Japanese development and use, especially in the field of ultra-high-frequency wire and cable has been favored and widely used. OBSH foaming agent advantages of the decomposition of the temperature is low, do not need to add decomposition aids; suitable for a variety of synthetic materials; extremely low toxicity, suitable for contact with food, such as the use of the foam, the use of the foaming agent, and the use of the foaming agent, and so on. Toxicity is very low, suitable for contact with food packaging materials; good electrical insulation properties; sulfurizing agent and foaming agent dual role; bubble holes fine and uniform.
At present, foreign countries have developed a variety of OBSH blowing agent modified series of products, such as Japan Yonghe Kasei’s N # 3000, 5000, 100S, 100M and other OBSH blowing agent modified products. China has also carried out research and development of OBSH blowing agent, at present, Shanxi Research Institute of Chemical Technology, Hangzhou Haihong company has built a small-scale production equipment. OBSH blowing agent due to the relatively high price, the application of certain restrictions.
(3) foaming agent DPT
Chemical name N, N’-di-nitroso-pentamethylene tetramine, mainly used as a rubber blowing agent, heat of decomposition, often adding urea, urea derivatives, melamine, etc. to prevent irritating odors, basically not used for plastic foaming, there are a number of domestic producers, such as the Beijing Chemical Industry Plant, Shanghai Auxiliary Plant, Nanjing Chemical Auxiliary Plant, Suzhou Auxiliary Plant, Hengyang Organic Synthesis Chemical Plant, etc., consumption is not high.
Physical foaming agent
There are more types of physical blowing agents, such as aliphatic hydrocarbons, chlorinated hydrocarbons, hydrochlorofluorocarbons and carbon dioxide gas, etc. Since the 1950s, monofluorotrichloromethane (CFC-11) has been widely used as the preferred blowing agent for polyurethane, which has a destructive effect on the ozone layer of the atmosphere, and in order to protect the earth’s ecological environment, the use of CFCS compounds must be banned. Over the years, domestic and foreign countries have been looking for and developing ideal alternative products. In addition to considering the nature of the blowing agent itself, the alternative blowing agent generally requires appropriate adjustment and improvement of raw materials such as polyether polyols, leveling agents, catalysts, etc., so that the formulation system can be optimized, so the key to the physical blowing agent lies in the development of alternative products and application research. So far, the foam blowing agent CFC ~ 11 replacement of the following four main programs.
(1) carbon dioxide blowing agent
There are two types of carbon dioxide blowing agent, one is isocyanate and water reaction to generate carbon dioxide (water foaming) as a blowing agent, the other is liquid carbon dioxide. Water foaming and CFC-11 compared to the advantages of carbon dioxide ODP (ozone depletion value) is zero, non-toxic, safe, there is no recycling problems, do not need to invest in the transformation of foaming equipment; disadvantages are higher viscosity of the polyol component in the foaming process, the foaming pressure and foam temperature are higher, the foam and the substrate bonding deteriorated, especially the thermal conductivity of the hard foam products; due to the carbon dioxide from the bubble hole Diffusion of carbon dioxide from the pores of the bubble faster, while the air into the pores slower, thus affecting the dimensional stability of the foam, although it can be improved by modification, but still not as good as CFC-11 foaming materials.
At present, it is mainly used in the fields of heating pipe insulation, packaging foam and agricultural foam, etc., which do not require high thermal insulation; liquid carbon dioxide foam has the same advantages and disadvantages as water foam, and is mainly used in polyurethane soft foam, and can be used in hard foam to overcome the shortcomings of water foam such as increasing the consumption of isocyanate, brittleness of foam, and poor adhesion with substrate, etc. However, liquid foam should be used for the foaming, and it is necessary to make the foaming of the foam to be more efficient. However, liquid foaming to improve the foaming machine, liquid carbon dioxide storage and transportation costs increase, liquid carbon dioxide foaming technology is still under continuous research and development.
(2) Hydrogenated hydrochlorofluorocarbon blowing agent
Hydrogenated hydrochlorofluorocarbon (HCFC) type blowing agent, molecules containing hydrogen, chemical properties are unstable, easy to decompose, so its ODP is much smaller than CFC-11, so HCFC is used as a first-generation alternative to CFC blowing agent, temporarily used during the transition period should be replaced by non-chlorine compounds as much as possible in a short period of time.
At present, the European Union, the United States, Japan banned the use of HCFC-based blowing agent for the end of 2004, China’s deadline for the use of the year 2030. At present, the most mature product that can replace CFC-11 commercially is HCFC-14LB, which has good compatibility with polyol and isocyanate, and can directly replace CFC-11 with HCFC-14LB under the condition of not increasing the equipments, and the dosage is less than that of CFC-11 in achieving the same density and similar physical characteristics of the foam. The drawbacks of HCFC-141B are that the raw material is expensive, it is soluble in some ABS and high-impact polystyrene, and its thermal conductivity is higher than that of CFC-11, so it requires a higher density of the foam body to achieve the thermal insulation effect.
Another class of hydrochlorofluorocarbon products replacing CFC-11 is the 60:40 mixture of HCFC-22/HCFC-14LB, which is the most commonly used solvent in industrial production, with mature production technology and moderate price, with the disadvantage that the solubility of the HCFC-22/HCFC-141B system in general polyols is relatively low, and the processing of HCFC-22-containing The disadvantage is that the solubility of HCFC-22/HCFC-141B system in general polyol is relatively low, and processing of polyol containing HCFC-22 is relatively difficult. In addition, the ODP value of HCFC-124 is only 1/5 of that of HCFC-141B, allowing a longer service life, and some foreign enterprises plan to use it in building and refrigerator appliance foams to compete with the higher-cost hydrofluoroalkanes (HFC).
(3) Hydrocarbon blowing agents
Hydrocarbon compounds used as polyurethane blowing agents are mainly cyclopentane, especially cyclopentane’s rigid foam system has the advantages of lower thermal conductivity and anti-aging properties, zero ODP value, etc. It is often used in the fields of refrigerator, cold storage and building thermal insulation, and has become the first choice of rigid foam CFC-11 substitutes in China.
In addition to n-butane, isobutane as an auxiliary blowing agent, the preparation of cyclopentane polyurethane rigid foam must solve the following two problems, the selection of explosion-proof equipment to solve the problem of cyclopentane flammable, explosive; the use of certain measures such as n-pentane, isopentane and cyclopentane together, can improve the foam mobility, thereby solving the problem of poor solubility of cyclopentane in polyether polyol.
In recent years, the production and development of cyclopentane in China has made great progress, and high purity cyclopentane can be obtained through depolymerization, hydrogenation and other processes with ethylene cracking by-product C5 as raw material. Beijing Research Institute of Chemical Industry undertook the “cyclopentane product development” project through the appraisal, at present the domestic Longshan Chemical Factory in Jilin, Beijing Oriental Chemical Factory, Nanjing Hongbao Li Company Limited and so on has been successfully constructed cyclopentane production equipment, and with a number of famous domestic refrigerator manufacturers, to provide cyclopentane-type combination of polyether used as foaming materials. materials.
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Translated with DeepL.com (free version)
