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| GoodRich MAGMA Industrial Technologies Limited OFFERS FORMALDEHYDE & UREA FORMALDEHYDE RESIN PLANTS FOR MDF, PARTICLEBOARD & PLYWOOD MANUFACTURERS IN THE CAPACITY RANGE FROM 10 TONS TO 100 TONS PER DAY |
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The chemical compound formaldehyde (also known by IUPAC nomenclature as methanol), is a gas with a strong pungent smell. It is the simplest aldehyde. Formaldehyde is a colorless gas at room temperature and pressure, with a density of 1.03. It is not commercially available as a gas, and is normally used in a solution of 37% formaldehyde, as Formaldehyde gas is readily soluble in water. The water solution is colorless, and has a very strong, pungent odor. This product is called by Trade names such as Formalin or Formol. Formaldehyde is also soluble in many of the common organic solvents, such as benzene and acetone. Its melting point is �118oC and its boiling point is �19oC in the gaseous form & 97oC in the form of 37% solution. Formaldehyde is also readily oxidized by atmospheric oxygen to form formic acid. Formaldehyde solutions must be kept tightly sealed to prevent this from happening in storage.
PROCESS FOR MAKING FORMALDEHYDE- Formaldehyde is produced by the catalytic oxidation of methanol.Worldwide, formaldehyde synthesis involves two optional routes -
In both processes, methanol is vaporised by warming, mixed with air and possibly recycle gas, and introduced into a vessel containing a catalyst. The catalyst assists the oxidation of methanol into formaldehyde in a reaction which is almost complete and is highly selective. After leaving the catalyst chamber, the hot gases containing the formaldehyde are cooled through a heat exchanger to remove heat energy. The cooled gases then pass into absorption columns where the formaldehyde and small traces of unreacted methanol are absorbed into water to produce a high strength aqueous solution of formaldehyde. The gas leaving the absorber is principally nitrogen but does contain significant amounts of other gases including traces of formaldehyde. In some plants, most of the gas leaving the absorber is re-used and the balance is heated in a catalytic converter to convert all the gases (except nitrogen) to carbon dioxide and water prior to release to atmosphere. If necessary, the formaldehyde solution from the absorber is passed through a de-acidification tower to remove traces of formic acid.At various stages of the process, heat produced can be recovered by generating steam.
PLANT DESCRIPTION FOR MAKING FORMALDEHYDE- �
Goodrich through their principals, offers Formaldehyde making technology. Our prinicipals have made big strides in the last 15 years to make the process simple & cost-effective. The technology is based on Silver catalyst, with the following advantages �
Formaldehyde Plants offered by GoodRich are the most efficient, which can be commissioned within a short period of 6 months. They could achieve their installed capacities almost immediately on start-up, without encountering any teething problems.
MANUFACTURING PROCESS FOR FORMALDEHYDE-
Formaldehyde is the oxidation/dehydrogenation product of methanol with oxygen in the presence of silver catalyst.
A fixed quantity of methanol and water is introduced into a mixing vessel from where this mixture is taken into an evaporator. Air is also introduced into the evaporator. A temperature of 70 0C is maintained which facilitates for the evaporation of methanol. The air and methanol vapour mixture is further heated to 100 0C. in the Superheater and then introduced into the Reactor where in presence of silver catalyst maintained at a temperature of 650 0C, the oxidation / dehydrogenation reaction takes place as per the following chemistry �
CH3OH = HCHO + H2
H2 + � O2 = H2O
CH3OH + � O2 = HCHO + H2O
ABSORPTION-
The reaction gas containing Formaldehyde, unreacted Methanol and water vapour is absorbed by circulating and cooling the Formaldehyde solution from the absorber sump. The part of the circulation is taken out as product.
Mostly the absorber is packed with pall rings. If proper packing size and cooling is maintained,more than 95% absorption is completed in the absorption column - I.
The unabsorbed gas from the absorption column - I is absorbed in the absorption column - II bycirculating and cooling absorber sump dilute Formaldehyde solution. Finally the gas is washed with pure DM water at the upper part of the column, provided with bubble cap trays and then exhausted as tail gas to the atmosphere.
RAW MATERIAL AND UTILITIES CONSUMPTION PER TONNE OF FORMALDEHYDE-
FORMALDEHYDE PLANT DETAILS-
LABOUR REQUIREMENT FOR PLANT OPERATION-
FLOW DIAGRAM OF FORMALDEHYDE PLANT-
FORMALDEHYDE (37%) RETAIL MARKET PRICES IN MUMBAI (January,2006)
Packing:
: 230/100 kgs net in HDPE carboy drums / 35 kgs HDPE blue colour carboys.
USES OF FORMALDEHYDE-
Formaldehyde is a raw material for many types of industries as per details given below :-
Manufacture of Moulding Powders:
Resins:
Pharmaceutical Industries:
Explosives:
Other uses:
The manufacture of amino and phenolic resins accounted for 55% of the total formaldehyde demand. Wood products accounted for 36% of the total demand, with MDF & particle board first and plywood second. Some other products that use formaldehyde include disinfectant in houses, ships, utensils and clothes, in glass mirrors, waterproofing fabrics, explosives, and slow release fertilizers. It is also used as a preservative in wheat and oats, and as an embalming agent. There are hundreds of other uses, since formaldehyde is used as an intermediate in the production of other chemicals and resins, such as phenolic, polyacetal, and melamine resins, and also methylene dianiline.
There is a great demand for the use of formaldehyde in a wide range of applications. Formaldehyde is primarily produced for the use in the manufacturing of chemical resins and as a chemical intermediate. The polymer industry is an example of how formaldehyde is used as an intermediate. Formaldehyde is also heavilyrelied on as a fumigant, disinfectant, embalming fluid and a wood preservative. The wood manufacturing industry accounts for 36% of the demand for formaldehyde worldwide. In the wood manufacturing industry formaldehyde is used as cell preservative due to its cost and ease of production. It is also highly effective in preventing microorganisms from invading wood products.
FORMALIN TECHNICAL-
Formalin technical is a water-methanol solution of formaldehyde. A part of unreacted methanol stays in the solution as a depolymerizer, preventing paraformaldehyde precipitation.
Applications: It is used as a raw material in manufacture of plastics, paints, synthetic resins and adhesives, tanning agents, insulating materials, disinfectants and medicines, textile auxiliary materials, as a disinfectant in agriculture, as well as in many organic syntheses.
HEALTH EFFECTS OF FORMALDEHYDE-
Because formaldehyde resins are used in many construction materials, including plywood, carpet, and spray-on insulating foams, and because these resins slowly give off formaldehyde over time, formaldehyde is one of the more common indoor air pollutants. At concentrations above 0.1 mg/kg in air, inhaled formaldehyde can irritate the eyes and mucous membranes, resulting in watery eyes, headache, a burning sensation in the throat, and difficulty in breathing.
Large formaldehyde exposures, for example from drinking formaldehyde solutions, are potentially lethal. Formaldehyde is converted to formic acid in the body, leading to a rise in blood acidity, rapid, shallow breathing, hypothermia, and coma or death. People who have ingested formaldehyde require immediate medical attention.
In the body, formaldehyde can cause proteins to irreversibly bind to DNA. Laboratory animals exposed to large doses of inhaled formaldehyde over their lifetimes have developed more cancers of the nose and throat than are usual. However, some studies suggest that smaller cocentrations of formaldehyde like those encountered in most buildings have no carcinogenic effects. Formaldehyde is classifed as a probable human carcinogen.
FORMALDEHYDE EMISSION FROM UREA FORMALDEHYDE RESINS-
Few issues in the forest products industry rival the debate and concern over the emission of formaldehyde from products bonded with urea-formaldehyde adhesive resins. This issue originated in the mid-1970s as the increasing use of formaldehyde-emitting panel products in the more tightly constructed homes led to numerous complaints. This has resulted in an increasing scrutiny of formaldehyde emission levels from building products used within homes by state and national regulatory agencies, including the Housing and Urban Development (HUD) and the Environmental Protection Agency (EPA), and the adoption by industry of voluntary standards for the emission of formaldehyde from wood products bonded with urea-formaldehyde adhesive resin, most notably MDF & particleboard. Similar concerns in Europe led to the well-known E-l standard limiting formaldehyde emissions from MDF & particleboard used in construction. In response to consumer concerns and regulatory actions, the particleboard, medium-density fiberboard and hardwood plywood industries have made major strides in reducing formaldehyde emission levels from products bonded with urea-formaldehyde adhesive resins.
The evolution of formaldehyde from urea-formaldehyde materials is incontrovertible. Over the past 40 years, investigators have examined extensively the structure of components of urea-formaldehyde resin systems and the physical chemistry of their formation and degradation in aqueous solutions. Classical kinetic, chromatographic, and NMR techniques have been applied. It can be concluded from these studies that the reactions leading to the formation ofurea-formaldehyde products formed during urea- formaldehyde resin synthesis and cure are reversible. In the forward direction, water iseliminated; therefore, the reverse reactions can be viewed as hydrolysis, which leads to the release of formaldehyde. Because most, if not all, of these reactions are catalyzed by acid, the use of an acid catalyst to hasten bond cure unfortunately also increases the rate of hydrolysis and formaldehyde liberation.
The reduction in formaldehyde emission levels from products bonded with urea-formaldehyde adhesive resins has been achieved by employing one or more of several technological methods. In general, these methods include:
The most widely used approach for reducing formaldehyde emission levels has emphasized decreasing the mole ratio of F/U. Ratios of about 1.6 that were common 10 to 15 years ago have now been reduced to values as low as 1.0 and, in some cases, lower. Unfortunately, lowering the F/U ratio produces resins with less tolerance for processing variations and panels that often have poorer physical and structural properties. As a consequence, some panel manufacturers use adhesive resins with a higher F/U ratio and employ other methods to achieve the necessary reduction in formaldehyde emission levels.
Recent research has suggested that Resins cured with the amine hydrochlorides had less formaldehyde liberation than those cured with ammonium chloride. This indicates that the incorporation of flexible polyamines offers promise for improving the durability and stability of urea-formaldehyde bonded wood products and possibly for reducing formaldehyde emissions.
Urea formaldehyde resin is a major commercial adhesive, especially within the forest products industry. It offers a number of advantages when compared with other adhesive systems. However, despite the fact that great strides have been made to offset its major disadvantage by lowering the formaldehyde emission levels of products bonded with urea formaldehyde adhesive resin, the industry still faces the possibility of more restrictive regulations on formaldehyde emissions.
METHANOL, THE RAW MATERIAL FOR FORMALDEHYDE-
FORMALDEHYDE is manufactured from Methanol as its raw material. Methanol is a petrochemical product manufactured by fertilizer plants and also from natural gas.
Methanol, also known as methyl alcohol or wood alcohol, is a chemical compound with chemical formula CH3OH. It is the simplest alcohol, and is a light, volatile, colourless, flammable, poisonous liquid that is used as an antifreeze, solvent, fuel, and as a denaturant for ethyl alcohol.
PROCESS FOR MAKING METHANOL-
Methanol is produced mainly from natural gas. Naphtha, fuel oil and coal are other suitable feedstocks. Modern industrial scale methanol production is based exclusively on synthesis gas mixture of hydrogen, carbon monoxide and carbon dioxide at a pressure of 50 - 100 atm and 250 - 300oC in the presence of copper catalyst (low pressure process).
STRUCTURE OF THE INDIAN INDUSTRY-
There are 8 methanol units spread all over the country with licensed capacities of 5,00,000 TPA. The demand for methanol is more than 10,00,000 tonnes in the country and presently methanol is imported in large quantities.
INTERNATIONAL STATUS-
The present installed world capacity of methanol is about 40 million TPA. There are in total 150 methanol plants with capacities ranging from 50,000 TPA to 825,000 TPA. The current world consumption is around 36 million TPA. The chemical demand is 30 million TPA and fuel demand 6 million TPA.
METHANOL SAFETY DATA SHEET-
APPLICATIONS OF METHANOL- Methanol is the simplest alcohol, containing one carbon atom. It is a colourless, tasteless liquid with a faint odor, commonly known as "wood alcohol". Methanol is used to produce many synthetic organic compounds and forms part of many commercially available solvents. Some of the better known chemicals are formaldehyde, chloromethanes, methylamines, DMT, pesticides, various bulk drugs, methyl methacrylate, dye intermediates, etc.
USES OF METHANOL-
Methanol is used in the following products / industries:
STORAGE OF METHANOL-
Methanol should be stored in areas protected from flames, sparks and excessive heat. M.S. tanks are suitable for storage. It is mostly supplied in bulk by tankers.
CAPACITIES OF METHANOL PLANTS IN INDIA-
METHANOL RETAIL MARKET PRICES IN MUMBAI (January,2006)
As against the above, the High-sea price of imported methanol is Rs.14.40 per kg and the landed cost to the factory is around 17.00 per kg. with concessional import duty for plywood, particle board and MDF manufactures. UREA FORMALDEHYDE RESINS (UF RESINS)- UF resin is by far the dominant adhesive for MDF, Particleboard and Plywood. It provides a strong adhesion in a permanently dry environment, cures fast and is relatively cheap. UF is applied to fibers, particles & flakes as an aqueous solution. It has an affinity for wood surfaces. In the presence of heat and an acidic catalyst (or hardener), UF condenses into a three-dimensionally cross-linked network thereby providing bonding PHYSICAL PROPERTIES-
These are typical values for Urea Formaldehyde (UF) resin. Values may be slightly different depending upon the specific grade of resin. Urea formaldehyde resin is a colourless to milky viscous liquid, with faint formaldehyde odour. It is soluble in water and alcohol. The free formaldehyde content of UF resins is usually less than 0.5 per cent depending on grade. MANUFACTURING PROCESS FOR UF RESIN- The building blocks for UF resin are urea and formaldehyde. Urea is synthesized from ammonia NH3 and carbon dioxide CO2 under heat and pressure into CO(NH2)2 and water H2O. Both ammonia and carbon dioxide are obtained from natural gas. Urea is a whitish crystal, traded in pellet form. Urea is best known as fertilizer. Its molecular weight is 60 The solubility of formaldehyde in water is very high. It has a characteristic odor detectable down to minute concentration of 0.3 parts per million (�ppm�) in the ambient air. Most people perceive formaldehyde as an irritant above a concentration of 1.0 ppm. Urea and formaldehyde are combined in a reactor into UF resin. It is shipped to engineered wood products� Plants as a colloidal aqueous solution with a solid content of about 65%. This liquid is odorless, slightly opaque, and, of course, not flammable. When shipped, the UF resin is already polymerized and cross linked to a certain degree. It has therefore a limited shelf life measured in days. In its semi-condensate form, UF solution consists of molecules in various interim steps such as mono-, di-, tri-, and tetramethylol ureas. In the solution, urea and formaldehyde are present at a molar ratio of about 1:1.11. The 10% excess of formaldehyde is needed to bring about the required reactions into a cross linked and glasslike solid. Decades ago, molar ratios as high as 1:2 were used. Emission of formaldehyde forced resin manufacturers to lower the molar ratio. Today�s 1:1.1 appears the lowest limit and requires an extremely tight control of the process parameters for manufacturing MDF and Particleboard. The manufacture of UF resins involves the reaction of formaldehyde with urea under controlled conditions. Notes:Related formaldehyde based resins are produced by the reaction of formaldehyde with phenol, melamine, resorcinol or combinations of these. UF resins are produced in a batch-wise process in vessels ranging from 5 tons up to 30 tonnes capacity. In the classical manufacturing method, the formaldehyde is charged to the reactor, at about 60�C, the contents made alkaline and then urea is charged during which time the temperature falls to about 40�C. The contents are then heated to about 120�C, the pH adjusted to approximately 5.0 and the reaction is allowed to proceed until the desired degree of polymerisation has occurred. The reaction is quenched with alkali and the contents cooled. Water may be stripped off in a dehydration stage and some further urea charged to react with excess formaldehyde. Critical reaction parameters are:
The individual steps of the manufacturing procedure are monitored and controlled by accurate instrumentation on the reactors and by in-process testing. The final products are comprehensively tested to prescribed specifications. As condensation proceeds, the viscosity increases and the resin eventually becomes hydrophobic. When the required degree of condensation has been achieved, the solution is neutralized, cooled and the PH adjusted to 7-8. Then the Resin is transferred to resin holding tank. RAW MATERIAL AND UTILITIES CONSUMPTION PER TON OF UREA FORMALDEHYDE RESIN-
UREA-FORMALDEHYDE PLANT DETAILS-
FLOW CHART FOR UF RESIN PLANT- CHEMISTRY OF UREA - FORMALDEHYDE RESIN FORMATION- Urea - formaldehyde resins are formed by the reaction of urea and formaldehyde. The overall reaction of urea with formaldehyde is quite complex and, although initially studied early in this century, is not completely understood even at the present time.
The synthesis of a urea-formaldehyde resin takes place in two stages. In the first stage, urea is hydroxymethylolated by the addition of formaldehyde to the amino groups. This reaction is in reality a series of reactions that lead to the formation of mono-, di-, and trimethylolureas. Tetramethylolurea is apparently not produced, at least not in a detectable quantity.
The addition of formaldehyde to urea takes place over the entire pH range. The reaction rate is dependent on the pH. The rate for the addition of formaldehyde to successively form one, two, and three methylol groups has been estimated to be in the ratio of 9:3:1, respectively. The exact ratio, of course, is dependent on the reaction conditions employed in the addition reaction.
The second stage of urea formaldehyde resin synthesis consists of the condensation of the methylolureas to low molecular weight polymers. The rate, at which these condensation reactions occur is very dependent on the pH and, for all practical purposes, occurs only at acidic pHs.
The difference between the pH profiles of the two stages of urea-formaldehyde resin synthesis is used to advantage in the production of urea-formaldehyde adhesive resins. In general, the commercial production of urea-formaldehyde adhesive resins is carried out in two major steps. The first step consists of the formation of methylolureas by the reaction of urea and formaldehyde under basic conditions with a pH of ~8-9. This step is carried out under basic conditions to allow the methylolation reactions to proceed in the absence of reactions involving the condensation of the methylolureas.
In the second step, the reaction mixture is brought to the acid side, with a pH of about 5, and the condensation reactions are carried out until a desired viscosity is reached. Then, the reaction mixture is cooled and neutralized. Water is removed by vacuum distillation to give a resin with a desired solids content (typically about 60-65%). Urea is often added in two, or sometimes more, steps. The initial addition of urea is made during the methylolation step, in which the formaldehyde-to-urea (F/U) ratio is typically large (~1.6-2). Usually, the second addition of urea is made during the condensation step. The second and any subsequent additions of urea lower the final F/U ratio to the desired level.
An acidic-cure catalyst is added to the urea formaldehyde resin before it is used as an adhesive. Ammonium chloride and ammonium sulfate are the most widely used catalysts for resins used by the forest products industry. A variety of other acids can be used as a catalyst, including formic acid, boric acid, phosphoric acid, oxalic acid, and acid salts of hexamethylenetetramine.
Resin cure is normally conducted at a temperature of ~120 �C and a pH < 5. The reactions that occur during the final cure of the resin are thought to be similar to those that occur during the acid condensation of the methylolureas. The traditional viewpoint is that these reactions lead to the formation of a cross linked polymeric network for the hardened, cured resin. However, there is evidence that a colloidal phase also occurs during resin cure. This evidence illustrates the lack of a full understanding of the physical and chemical processes leading to the cure of urea formaldehyde resin systems and the need for continued research.
GRADES OF UREA FORMALDEHYDE RESINS-
Urea formaldehyde resins are the product of formaldehyde polycondensation. They are used in manufacturing of wood Particleboards / MDF boards with emission classes of E0, E1 & E2 as well as in manufacturing plywood boards.
USES OF UF RESINS- Approximately 2 million metric tons of urea-formaldehyde resin are produced annually. More than 70% of this urea-formaldehyde resin is used by the forest products industry for a variety of purposes. The resin is used in the production of an adhesive for bonding particleboard (61% of the urea-formaldehyde used by the industry), medium density fiberboard (27%), hardwood plywood (5%), and a laminating adhesive for bonding (7%), for example, furniture case goods, overlays to panels, and interior flush doors.
Urea formaldehyde resins are the most prominent examples of the class of thermosetting resins usually referred to as amino resins. Urea formaldehyde resins comprise about 80% of the amino resins produced worldwide. Melamine formaldehyde resins constitute the remainder of this class of resins, except for minor amounts of resins that are produced from other aldehydes or amino compounds (especially aniline), or both.
The use of urea formaldehyde resins as a major adhesive by the forest products industry is due to a number of advantages, including low cost, ease of use under a wide variety of curing conditions, low cure temperatures, water solubility, resistance to microorganisms and to abrasion, hardness, excellent thermal properties, and lack of color, especially of the cured resin.
The major disadvantage associated with urea formaldehyde adhesives as compared with other thermosetting wood adhesives, such as phenol-formaldehyde and polymeric diisocyanates, is the lack of resistance to moist conditions, especially in combination with heat. These conditions lead to a reversal of the bond-forming reactions and the release of formaldehyde. For this reason, urea formaldehyde resins are usually used for the manufacture of products intended for interior use only. However, even when used for interior purposes, the slow release of formaldehyde (a suspected carcinogen) from products bonded with urea formaldehyde adhesives is a major concern that has come under close scrutiny by State and Federal regulatory agencies.
Adhesives based on formaldehyde are used as binders in the production of reconstituted wood panels such as particleboard, plywood, medium density fibreboard, laminated veneer lumber, finger joints and laminated beams. UF resins and other related formaldehyde resins are also used in resin impregnated decorative paper laminates, glass fibre insulation binders, foundry cores, pulp and paper processing aids, paper sizing, textile treatments, paints and enamels, and miscellaneous joinery applications.
CURING OF UF RESIN-
During hot pressing, the polymerization and condensation is completed. Shortly before the UF solution is sprayed onto the wood fibers for MDF or particles & flakes for Particleboard, a catalyst is added. It is an acid; most UFs condense fastest with a pH range of 3�4 (7 is neutral). Now the UF solution�s shelf life is reduced dramatically and measured in hours. In the presence of heat supplied during pressing, the pre-condensated UF cross links into a solid resin. During the hot pressing, a portion of the excess formaldehyde is emitted. The reaction is reversible: too much heat hydrolyses the UF resin into urea and formaldehyde thereby degrading the bond and releasing even more formaldehyde. It is therefore of critical importance to precisely control pressing time and immediately cool the finished panels after completion of the pressing.
The UF system has these additional components optimized for each plant:
Catalyst(or Hardener):-Salts such as ammonium chloride often combined with hexamethylentetramine create an acidic environment during hot pressing, finalizing the condensation.
Buffer:To prevent precuring of UF prior to hot pressing, a buffering agent is added such as ammonia or urea. It neutralizes the small amount of catalytic acid generated during room temperature thereby avoiding a pre-mature curing.
Scavenger:Even at a molar ratio as low as 1:1.11, free formaldehyde is emitted during hot pressing.Agents such as specific ureas capable of absorbing the formaldehyde prior to any emissions, so-called formaldehyde scavengers, are added to the UF solution.
Wax:To slow down the rate of liquid water absorption of the MDF or Particleboard during its end-use application, wax as hydropholic agent is added as an aqueous dispersion with a solid content of typically 50%. Solid wax addition amounts to about 1% relative to the dry wood weight of MDF or Particleboard panel.
Others:To impart MDF or Particleboard special attributes such as resistance to fungi or retardation against burning, a host of additives are available for such special applications. But it should be noted that some 95%+ of today's consumed MDF or Particleboard volumes do not require such special treatments.
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