Methods for reducing emissions of volatile compounds from a product

Abstract

A process for reducing emissions of volatile compounds from a product selected from a body panel or body shell, wherein the process comprises the following: Positioning a product comprising a polymeric material and a body panel or body shell in a chamber; Establish a negative pressure environment with a negative pressure of less than or equal to 6.7 hPa (5 mmHg) inside the chamber; Heating the product in the chamber to a temperature of 125 °C or greater, but less than or equal to 300 °C, sufficient to evaporate any volatile compound contained in the polymeric material; and Extraction of a gas stream containing vapors of the volatile compound from the chamber, wherein the extracted gas stream is condensed into a liquid phase to produce a liquid condensate that includes the volatile compound.

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to a method and apparatus for reducing emissions of volatile compounds from products made from polymeric materials. INTRODUCTION

[0002] Polymeric materials are used in a wide variety of applications, including the manufacture of plastics, fibers, paints, adhesives, elastomers, rubbers, foams, and coatings. Such materials are formed by polymerization, crosslinking, or curing, in which many small molecules, called monomers, react with each other or with other intermediate reaction products to form polymers or large macromolecules composed of multiple repeating units. In practice, an organic solvent, catalyst, or initiator may be used as a polymerization aid. During manufacturing, polymers are typically combined or blended with additives, modifiers, plasticizers, reinforcing materials, or fillers to customize the chemical, mechanical, physical, cosmetic, and / or processing properties of the resulting polymeric materials.

[0003] Products made from or containing polymeric materials can, under certain conditions, emit volatile compounds over time. These volatile compounds can include, for example, unreacting residual monomers, formed dimers, oligomers, additives, modifiers, moisture, solvents, residual catalysts, reaction by-products, and decomposition products of the polymeric materials themselves. Some of these volatile compounds may be incorporated into the polymeric materials during product manufacture and evolve slowly over time, while others may develop after product manufacture under certain environmental conditions.

[0004] US 2010 / 0146 808 A1 describes a method for drying paint applied to a painted article, comprising the steps of: (a) controlling a first pressure within the enclosure by drawing air from inside the enclosure through a first outlet and preventing air from entering the enclosure through any opening within the enclosure, such that the first pressure inside the enclosure is lower than a second pressure outside the enclosure, and (b) maintaining the first pressure within the enclosure to provide a selected time for drying paint applied to the painted article. SUMMARY

[0005] Emissions of volatile compounds from a product comprising a polymeric material and a body panel or body-in-white may be reduced or eliminated from the product by a process comprising placing the product in a chamber, creating an environment having a negative pressure of less than or equal to 5 mmHg within the chamber, and heating the product within the chamber to a temperature equal to or greater than 125°C but less than or equal to 300°C sufficient to vaporize a volatile compound contained in the polymeric material such that vapors of the volatile compound are removed or released from the product. A gas stream comprising vapors of the volatile compound is then withdrawn from the chamber and condensed to a liquid phase to produce a liquid condensate comprising the volatile compound.The liquid condensate can be pumped into a storage tank for further processing.

[0006] The polymeric material may comprise at least one polymer or copolymer selected from the group consisting of: acetals; acrylates; acrylonitrile-butadiene-styrene; alkyds; diallyl phthalate; epoxy; fluorocarbons; melamine-formaldehyde; nitrile resins; phenols; polyamides; polyamide-imides; poly(aryl ethers); polycarbonate; polyesters; polyimides; polymethylpentene; polyolefins; polyphenylene oxide; polyphenylene sulfide; polyurethanes; silicones; styrenes; sulfones; urea-formaldehyde; vinyls; and combinations thereof.

[0007] In one form, the volatile compound extracted from the product may have a normal boiling point of less than 100°C at normal atmospheric pressure. In another form, the volatile compound extracted from the product may be an organic compound and have a normal boiling point greater than or equal to 100°C at normal atmospheric pressure and a vapor pressure less than or equal to 5 mmHg at 20°C. The product may be heated within the chamber to a temperature below the normal boiling point of the volatile compound.

[0008] In one form, the product may comprise a fiber-reinforced polymer and the volatile compound a styrene compound. In this case, the fiber-reinforced polymer may be subjected to a negative pressure of less than or equal to 2 mmHg within the chamber and heated to a temperature greater than or equal to 150°C to vaporize the styrene compound.

[0009] In another form, the polymeric material may comprise a polymeric adhesive or sealant, and the volatile compound may comprise an organic solvent and / or a plasticizer. In this case, the product may be exposed to a negative pressure of less than or equal to 2 mmHg within the chamber and heated to a temperature greater than or equal to 125°C to evaporate the organic solvent and / or plasticizer.

[0010] In one form, the volatile compound may comprise a compound having a heat of vaporization in the range of 5 kJ / mol to 150 kJ / mol.

[0011] According to the invention, the product comprises a body panel or a body shell. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of a system for extracting volatile compounds from products comprising polymeric materials; Fig. Figure 2 is a plot of vapor pressure (mmHg) versus temperature (°C) for several styrene monomers and dimers at pressures up to 760 mmHg (1 atm); Fig. Figure 3 is a graph of vapor pressure (mmHg) versus temperature (°C) for equal styrene monomers and dimers, illustrated in Fig. 2 at negative pressures of up to 25 mmHg (~0.033 atm); Fig. Figure 4 is a graph of vapor pressure (mmHg) versus temperature (°C) for several volatile compounds found in adhesives and sealants at pressures up to 760 mmHg (1 atm); and Fig. Figure 5 is a graph of vapor pressure (mmHg) versus temperature (°C) for the same volatile compounds, illustrated in Fig. 4 at negative pressures of up to 25 mmHg (~0.033 atm). DETAILED DESCRIPTION

[0012] Emissions of volatile compounds from products made of or containing polymeric materials can be eliminated, reduced, or controlled by a process in which the products are heated in a vacuum or under atmospheric pressure for a sufficient time to extract or release volatile compounds from the polymeric materials. The temperatures and pressures used in the extraction of volatile compounds can be selected to allow specific volatile compounds to be released from the products without compromising various properties, including structural integrity, dimensional stability, or overall robustness of the products. The volatile compounds released from the polymeric materials can be condensable and can be captured or recovered by condensing the volatile compounds into a liquid phase.The collected or recovered liquid phase can be reused, for example, in the production of other polymeric materials. The extraction of volatile compounds can be performed on one or more intermediate or final products and can be performed at any suitable stage of the product manufacturing process.

[0013] As used herein, the term "polymeric material" refers to any material that comprises or contains a polymer and may include composite materials that include a combination of a polymer and a non-polymeric material. The term "polymer" is used broadly to refer to both homopolymers and heteropolymers. Homopolymers consist of a single type of polymer, whereas heteropolymers (also called copolymers) consist of two (or more) different types of monomers. The polymeric materials described herein may include one or more of the following thermosetting or thermoplastic polymers: acetals, including polyoxymethylene (POM); acrylates, including poly(methyl methacrylate) and poly(methyl acrylate); acrylonitrile butadiene styrene; alkyds; diallyl phthalate; epoxy;Fluorocarbons, including poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), perfluoroalkoxy resin, fluorinated ethylene-propylene resin, poly(vinylidene fluoride), ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer and poly(vinyl fluoride); melamine-formaldehyde; nitrile resins; phenols; polyamides; polyamide-imides; poly(aryl ethers); polycarbonate; polyesters; polyimides; polymethylpentene; polyolefins, including polyethylene, polypropylene, polybutylene and polyallomers; polyphenylene oxide; polyphenylene sulfide; polyurethanes; silicones; styrene, including polystyrene, styrene-acrylonitrile copolymer and styrene-butadiene copolymer; sulfones, including poly(ether-sulfone), poly(phenyl sulfone) and polysulfone; block copolymers; urea-formaldehyde; and vinyls, including polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyrate, polyvinyl formal and polyvinyl alcohol.;

[0014] The products can be made from polymeric materials or from a combination of polymeric and non-polymeric materials. Some examples of forming processes for polymeric materials include molding, extrusion, casting, and drawing. Some polymeric materials can comprise composites, which can include a polymer matrix phase and a reinforcement phase of fibers or particles dispersed throughout the continuous polymer matrix phase. The reinforcement phase can comprise a polymeric material or a non-polymeric material, such as glass, aramid, or carbon. In one form, the reinforcement phase can comprise a plurality of short or continuous fibers interconnected by the polymer matrix phase and can therefore be referred to as a fiber-reinforced polymer.Some examples of composite manufacturing processes include sheet molding, injection molding, resin transfer molding, pre-preg lay-up, pultrusion, filament winding, and thermal deformation. Some polymeric materials can be formulated for use as adhesives or sealants and can be used to attach or form a seal between two or more polymeric or non-polymeric materials.

[0015] Volatile compounds may be incorporated into products made from or containing polymeric materials and may also be present in the products themselves after curing (polymerization). Without prejudice to the intention to be bound by theory, it is believed that the presence of volatile organic or inorganic compounds in polymeric materials is due to the precursor compositions used to manufacture the polymeric materials. For example, some polymeric materials are intentionally formed from polymeric precursor compositions that contain a stoichiometric excess of one or more liquid reactants, e.g., a stoichiometric excess of monomers or polymers. In addition, certain polymeric precursor compositions may contain liquid additives or modifiers, e.g.,Organic solvents and / or plasticizers that are not involved in the polymerization reaction but are added for the purpose of adjusting the rheological or thixotropic properties of the precursor compositions. Since these precursor compositions may therefore contain one or more liquid components that are not consumed or otherwise eliminated during polymerization, the resulting polymeric materials may contain residual liquid components that, under certain temperature and pressure conditions, may evaporate or otherwise physically evolve from the polymeric materials even after polymerization is complete.

[0016] Some examples of liquid components that may be present in cured or partially cured polymeric materials include: residual monomers or oligomers, residual catalysts or initiators, plasticizers, solvents, e.g., organic solvents, and intermediate reaction products. Some examples of residual monomers that may be present in cured or partially cured polymeric materials include: alcohols, aldehydes (e.g., formaldehyde), alkenes, amides, amines, anhydrides, aromatic hydrocarbons, carboxylic acids, dienes, esters, ethers, imines, isocyanates, ketones, nitriles, and phenols (e.g., phenolformaldehyde). Some examples of catalysts or initiators used in polymeric precursor compositions include: organometallic compounds, transition metals, transition metal halides, peroxides, free radical initiators, and ionic initiators.Specific catalysts or initiators include carbon disulfide and carbonyl sulfide. Some examples of plasticizers used in polymeric precursor compositions include: adipates, azelates, benzoates, epoxy, esters, mellitates, trimellitates, phosphates, phthalates, polybutene, sebacates, sulfonamides, terephthalates, and orthophthalates. Some specific examples of plasticizers include: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) and tris-decylbenzene-1,2,4-tricarboxylate or tridecyl trimellitate (TDTM). Some examples of organic solvents used in polymeric precursor compositions include: alcohols, acetates, saturated, unsaturated, and aromatic hydrocarbons, ethers, and esters.Some specific examples of compounds that may be present in cured or partially cured polymeric materials include: saturated hydrocarbons (paraffins, alkanes, or cycloalkanes), such as butane, pentane, hexane, heptane, octane, (nonane), decane, pentadecane, and hexadecane; unsaturated hydrocarbons (olefins, alkenes, or alkynes), such as butene, isobutylene, 1,3-butadiene, propene, ethylene, and pentene; aromatic hydrocarbons (arenes), such as benzene, toluene, xylene, styrene, naphthalene, biphenyl, and phenol; halogenated hydrocarbons, formic acid, and methanol.

[0017] The volatile organic or inorganic compounds that can be vaporized, removed, and subsequently recovered by condensation from products consisting of polymeric materials may have relatively high boiling points and relatively low vapor pressures and thus diffuse relatively slowly from cured or partially cured polymeric materials under normal temperature and pressure conditions. In one form, the volatile organic or inorganic compounds may have boiling points greater than or equal to 100°C at normal atmospheric pressure (i.e., 760 mmHg, 101.3 kPa, or 14.7 psi) and / or vapor pressures less than or equal to 6.7 hPa (5 mmHg) at 20°C. The boiling point of a compound at normal atmospheric pressure may be referred to as the compound's "normal" boiling point.For example, the boiling point of the volatile organic or inorganic compounds at normal atmospheric pressure may be greater than or equal to 125 °C, 150 °C, or 200 °C; less than or equal to 400 °C, 350 °C, or 300 °C; or between 125 °C and 400 °C, 150 °C and 350 °C, or 200 °C and 300 °C. In addition, the vapor pressure of the volatile organic or inorganic compounds at 20 °C may be greater than 0 hPa (0 mmHg), greater than or equal to 1.3 10. -7 hPa (10 -7 mmHg) or greater than or equal to 1.3 10 -4 hPa (10 -4 mmHg); less than or equal to 6.7 hPa (5 mmHg), 1.3 (1 mmHg) or 0.13 hPa (0.1 mmHg); or between 0 hPa (0 mmHg) and 6.7 hPa (5 mmHg), 1.3 10 -7 hPa (10 -7 mmHg) and 1.3 hPa (1 mmHg), or 1.3 10 -4 hPa (10 -4mmHg) and 0.13 hPa (0.1 mmHg). In a specific example, the volatile organic or inorganic compounds may have boiling points greater than 250 °C at normal atmospheric pressure and / or vapor pressures less than or equal to 0.13 hPa (0.1 mmHg) at 20 °C.

[0018] In some situations, the volatile organic or inorganic compounds that can be evaporated, removed, and subsequently recovered by condensation from products containing polymeric materials may have relatively low boiling points and relatively high vapor pressures, but these cannot be easily released from the products due to the chemical and / or mechanical properties of the products, the physicochemical properties of the volatile compounds, and / or the presence of other volatile compounds within the product. For example, the rate at which a volatile compound can be extracted from a polymeric material in a product may depend on one or more of the following properties of the polymeric material: density, porosity, affinity for the volatile compound, diffusion coefficient, geometry, and / or dimensions.Furthermore, the rate at which a volatile compound can be extracted from a polymeric material may depend on one or more of the following properties of the volatile compound: molecular weight, structure, volatility, and adsorption coefficient. In one form, these volatile organic or inorganic compounds may have boiling points of less than 100°C or even less than 25°C at normal atmospheric pressure (i.e., 760 mmHg, 101.3 kPa, or 14.7 psi). In this case, the presently disclosed extraction process can be used to actively remove these volatile organic or inorganic compounds from the products.

[0019] The volatile organic or inorganic compounds that can be evaporated, removed and subsequently recovered by condensation from products containing polymeric materials can also have a latent heat of vaporization (ΔH vap) in the range of 5 kJ / mol to 150 kJ / mol, in the range of 10 kJ / mol to 100 kJ / mol or in the range of 30 kJ / mol to 60 kJ / mol.

[0020] The emission of volatile organic or inorganic compounds from a product comprising a polymeric material can be eliminated, reduced, or controlled by extracting the volatile organic or inorganic compounds from the product. In general, a volatile organic or inorganic compound can be extracted and optionally recovered from a product comprising a polymeric material by: (i) enclosing the product in a chamber, (ii) creating a vacuum or negative pressure environment within the chamber, (iii) heating the product to a temperature sufficient to vaporize the target compound within the product so that vapors of the target compound are released from the product, and (iv) continuously removing the released vapors from the chamber as an effluent stream.The vapors of the target compound released from the product can then be recovered, for example, by cooling the vapors to a temperature below a boiling point of the vapors to condense the vapors in the effluent stream to produce a liquid condensate comprising the target compound. In situations where the effluent stream contains two or more target compounds with different boiling points, a first liquid condensate can be recovered from the stream by cooling the stream to a first temperature and a second liquid condensate can be recovered from the stream by subsequently cooling the stream to a second temperature below the first temperature. This can be achieved by passing the stream through two or more condensers arranged in series or by feeding the stream to a distillation column designed to separate multiple volatile compounds from one another.In one form, the vapors of the target compound released from the product can be burned.

[0021] The effective extraction of volatile compounds from the product is achieved by controlling the pressure in the chamber, the temperature of the product during the extraction process, and the time the product is exposed to such temperatures and pressures. In one form, the product is heated in the chamber during the extraction process to a temperature equal to or greater than the boiling point(s) of the volatile compound(s) selected for extraction. The boiling point of a specific volatile compound depends on the ambient pressure, in this case, the pressure in the chamber. The boiling point of a volatile compound at a given pressure can be determined from experimental data or calculated, for example, using the Clausius-Clapeyron equation: lnP1P2=ΔHvapR(1T2−1T1) where ΔHvap is the enthalpy (heat) of vaporization of a specific volatile compound (in J / mol), R is the gas constant (~8.3145 J / mol-K), and P1 and P2 are the vapor pressures of the volatile compound (in mmHg) at two different temperatures T1 and T2 (in Kelvin). Therefore, if the latent heat of vaporization (ΔH vapIf the volatile compound's heat energy (P1) and vapor pressure (P1) at a specific temperature (T1) are known, we can calculate the temperature (T2) to which the volatile compound must be heated to volatilize it at a given pressure (P2). Other equations can alternatively be used to calculate the boiling point of a volatile compound at a given pressure, such as the Antoine, Riedel, and Wagner equations or the Design Institute for Physical Properties (DIPPR) correlation. For the latent heat of vaporization and vapor pressure of various organic and inorganic compounds, as well as the constants required in the Antoine, Riedel, and / or Wagner equations and / or the DIPPR correlation, see Don. W. Green et al., Perry's Handbook for Chemical Engineers, 8 thEd., 2008, pages 2-55-79, 2-145-155 and 2-477-478; the CRC Handbook of Chemistry and Physics; and James G. Speight, Lange's Handbook of Chemistry, 16 th Ed., 2005.

[0022] According to the invention, during the extraction process, the product is heated in the chamber to a temperature equal to or greater than 125°C and less than or equal to 300°C and subjected to a pressure of less than or equal to 6.7 hPa (5 mmHg). For example, during the extraction process, the product can be heated in the chamber to a temperature of 125°C or 150°C, but less than or equal to 300°C, preferably 200°C or 175°C. At the same time, the product can be subjected to a negative pressure of less than or equal to 2.7 hPa (2 mmHg), 1.3 hPa (1 mmHg) or 0.13 hPa (0.1 mmHg), but preferably greater than 0 hPa (0 mmHg). -7 hPa (10 -7 mmHg) or 1.3 10 -4 hPa (10 -4 mmHg).

[0023] The product can be exposed to certain desired temperature and pressure conditions for a period of time sufficient to reduce the amount of certain volatile compounds present in the product. The time required to reduce the amount of certain volatile compounds present in the product may depend on the temperature and pressure during the extraction process, as well as the chemical and mechanical properties of the product, the physicochemical properties of the volatile compound, and the presence of other volatile compounds. For example, the rate at which a volatile compound can be extracted from a polymeric material may depend on one or more of the following properties of the polymeric material: density, porosity, affinity for the volatile compound, diffusion coefficient, geometry, and / or dimensions.Furthermore, the rate at which a volatile compound can be extracted from a polymeric material may depend on one or more of the following properties of the volatile compound: molecular weight, structure, volatility, and adsorption coefficient. The residence time of a product in a selected temperature and pressure environment may need to be evaluated and controlled or adjusted based on the observed extraction or evaporation rate of the volatile target compound(s).

[0024] Fig. Figure 1 schematically illustrates a system 100 for extracting volatile compounds from products made with polymeric materials to eliminate or reduce the subsequent uncontrolled emission of such compounds therefrom. The system 100 includes a distillation chamber 110, a heater 112, a vacuum pump 114, a condenser 116, a reservoir 118, and a discharge pump 120.

[0025] The distillation chamber 110 includes a roof 122, side walls 124, and a floor 126 that define an interior 128 of the distillation chamber 110, as well as an outlet 130 through which a gas stream can be discharged from the distillation chamber 110. A temperature sensor 132 and a pressure sensor 134 can be coupled to the distillation chamber 110 to measure the temperature and pressure inside 128 of the distillation chamber 110 and communicate these measurements to a microprocessor or electronic control module (ECM) (not shown). The distillation chamber 110 is configured to contain within its interior 128 a product 105 that is made of or contains a polymeric material and thus may contain one or more volatile compounds that may be released from or formed from the product 105 under certain temperature and pressure conditions.The distillation chamber 110 can be constructed to contain a single product 105 or multiple products (not shown) simultaneously. The specific configuration of the distillation chamber 110 depends on the shape and size of the product 105(s) to be treated and may therefore vary from that shown in FIG. Fig. 1 illustrated.

[0026] The heater 112 is configured to heat a product 105 contained in the distillation chamber 110 to a temperature sufficient to vaporize a volatile compound contained in the product 105, such that vapors of the volatile compound are released from the product 105. The heater 112 may or may not be housed within the interior 128 of the distillation chamber 110 and may comprise any heat source or combination of heat sources capable of raising the temperature of a product 105 contained in the distillation chamber 110 or the temperature of the entire interior 128 of the distillation chamber 110 to a particular desired temperature. For example, the heater 112 may comprise one or more fuel-fired burners, electrical resistance heating elements, induction heating elements, a source of electromagnetic radiation, or a combination thereof.

[0027] The vacuum pump 114 includes an inlet 136 into which a gas stream is received and an outlet 138 through which a gas stream is discharged, the inlet 136 of the vacuum pump 114 being in fluid communication with the outlet 130 of the distillation chamber 110. The vacuum pump 114 is configured to create a vacuum or negative pressure environment within the interior 128 of the distillation chamber 110 such that a product 105 disposed within the chamber 110 is exposed to the negative pressure environment. In one form, the vacuum pump 114 may be part of an overall air evacuation, filtration, and treatment system (not shown).In combination, the heater 112 and the vacuum pump 114 are configured to subject a product 105 contained within the interior 128 of the distillation chamber 110 to a temperature and pressure sufficient to vaporize or volatilize a volatile compound contained within the product 105, thereby withdrawing or releasing vapors of the volatile compound from the product 105. The vacuum pump 114 can also be configured to transport or evacuate the released volatile compound vapors from the interior 128 of the distillation chamber 110 as an effluent stream. The effluent stream can be evacuated from the distillation chamber 110 and transported via a conduit 140 to the condenser 116. The line 140 may include a one-way check valve 142 to prevent backflow in situations where the pressure in the condenser 116 exceeds the pressure inside 128 of the distillation chamber 110.

[0028] The condenser 116 includes an inlet 144 in fluid communication with the outlet 130 of the distillation chamber 110 and an outlet 146 in fluid communication with the reservoir 118. The condenser 116 is configured to receive an effluent stream from the distillation chamber 110 and condense the volatile compound vapors released in the stream into a liquid phase referred to as the condensate. The condenser 116 may also be configured to separate the liquid condensate from the remaining components in the effluent stream. The liquid condensate comprising the volatile compound may be removed from the condenser 116 via the outlet 146 and transported to the reservoir 118 via a conduit 148. A valve 150 may be disposed within the conduit 148 to control the flow of liquid from the condenser 116 to the reservoir 118.Additionally, the condenser 116 may include a vacuum port 152, which may be connected to the inlet 136 of the vacuum pump 114 via another line 154. The remaining components of the effluent stream may be removed from the condenser 116 via the vacuum port 152 through the line 154. A vacuum shutoff valve 155 may be disposed within the line 154 to minimize pressure fluctuations in the condenser 116 and the interior 128 of the distillation chamber 110.

[0029] In one form, the condenser 116 may comprise a shell-and-tube or plate-and-frame heat exchanger and may include a coolant inlet 156 and a coolant outlet 158. In this case, a coolant may be introduced into the condenser 116 via the coolant inlet 156 and flow through the condenser 116 countercurrently with respect to the flow of the effluent stream through the condenser 116. The coolant may then be removed from the condenser 116 via the coolant outlet 158.

[0030] The liquid condensate may be collected and held in the reservoir 118. The liquid condensate may be drained from the reservoir 118 through a line 160 when the reservoir 118 is full or at any other time for any other reason. A valve 162 may be disposed within the line 160 to control the flow of the liquid condensate to the reservoir 118. In one form, the pump 120 may be used to pump the liquid condensate through the line 160 to another desired location.

[0031] A product 105 may be continuously heated and subjected to the vacuum in the distillation chamber 110 for a period of time sufficient to reduce the amount of volatile compounds contained in the product 105 to a desired level. In one form, a sensor or sampling port 164 may be connected to the interior 128 of the distillation chamber 110 or the conduit 140 and configured to detect the presence of one or more volatile compounds within the effluent stream exiting the distillation chamber 110 and / or to determine the concentration of those compounds within the effluent stream. In this case, the product 105 may be continuously heated and subjected to the vacuum in the distillation chamber 110 until the concentration of one or more volatile compounds in the effluent stream exiting the distillation chamber 110 is no longer detectable or is below a predetermined amount.The absence or relatively low concentration of volatile compounds within the effluent stream exiting the distillation chamber 110 can provide sufficient evidence that the concentration of volatile compounds contained in the product 105 has been effectively reduced or eliminated therefrom. EXAMPLES

[0032] The uncontrolled emission of volatile compounds from a product comprising a polymeric material can be eliminated or reduced by heating the product in a vacuum or subatmospheric pressure environment for a sufficient time to evaporate and release the volatile compounds from the product. The temperatures and pressures at which the volatile compounds are released from the product can be selected within the scope of claim 1 to maximize the rate at which the volatile compounds are released from the product while simultaneously avoiding adverse effects on various properties, including the structural integrity, dimensional stability, or robustness of the product. EXAMPLE 1

[0033] Fiber-reinforced plastics or polymers (FRP) are composite materials used in the manufacture of various consumer, commercial, and industrial products, such as aerospace, marine, and automotive body panels, high-performance sporting goods, building materials, appliance components, chemical containers, piping, and electrical equipment. The invention relates to use in products selected from a body panel or a body-in-white. The polymer precursor compositions or resin compositions used during the FRP manufacturing process may contain a stoichiometric excess of monomers, dimers, trimers, tetramers, and / or oligomers of styrene, wherein these residual styrene or styrene compounds may be included in the resulting FRP products. Some examples of styrene compounds include: styrene (C8H8); α-methylstyrene (C9H 10); 2,3-diphenyl-1-butene (C 16 H 16 ); 1,3-diphenyl-1-butene (C 16 H 16 ); 1,4-diphenyl-1-butene (C 16 H 16 ); 1-Ethyl-2(2-phenylethenyl)-benzene (C 16 H 16 ); 2,4-Diphenyl-4-methyl-1-pentene (C 18 H 20 ); and 2,4-diphenyl-4-methyl-2-pentene (C 18 H 20 The presently disclosed extraction process can be used to effectively reduce or eliminate the residual content of styrene and / or other styrenic compounds in these FRP products without compromising the structural integrity, dimensional stability, or robustness of the products.

[0034] Fig. Figure 2 illustrates a plot of vapor pressure (mmHg) as a function of temperature (°C) for the following monomers and dimers of styrene: styrene (C8H8) (solid line, 10); α-methylstyrene (C9H 10 ) (short dashed line, 20); 2,3-diphenyl-1-butene (C 16 H 16) (dash-dotted line, 30); 1,3-diphenyl-1-butene (C 16 H 16 ) (long dashed line, 40); and 1,4-diphenyl-1-butene (C 16 H 16 ) (dash-dot-dot line, 50) at pressures up to 760 mmHg (1 atm, 1013 hPa). The heat of vaporization or enthalpy of vaporization (ΔH vap) of the compounds at their boiling points is shown in the following table. The vapor pressure and latent heat of vaporization for each compound were obtained from Advanced Chemistry Development, Inc. (ACD / Labs): http: / / www.acdlabs.com / resources / ilab / . Vapor pressure curves 10, 20, 30, 40, and 50 represent the temperatures and pressures at which the gas phase of each compound is in equilibrium with its condensed phase. Thus, vapor pressure curves 10, 20, 30, 40, and 50 can be used to determine the temperatures and pressures required for vaporization and, thus, release of each styrenic compound from an FRP product during the specified extraction process. ΔH vap (kJ / mol) Styrol 36,65 α-Methylstyrol 38,26 2,3-Diphenyl-1-buten 50,78 1,3-Diphenyl-1-buten 52,81 1,4-Diphenyl-1-buten 54,94 1-Ethyl-2-(2-phenylethenyl)-benzol 53,66 2,4-Diphenyl-4-methyl-1-penten 54,92 2,4-Diphenyl-4-methyl-2-penten 55,01

[0035] As in Fig. 2, when carried out at normal atmospheric pressure (760 mmHg, 1013 hPa), normal curing temperatures (e.g., about 152 °C) may be sufficient to evaporate and thereby remove residual compounds of styrene (C8H8) from an FRP product, but are ineffective in the evaporation and removal of α-methylstyrene (C9H 10 ); 2,3-diphenyl-1-butene (C 16 H 16 ); 1,3-diphenyl-1-butene (C 16 H 16 ); or 1,4-diphenyl-1-butene (C 16 H 16 ) from the FRP product is not effective. This is because the boiling point of styrene (C8H8) at normal atmospheric pressure is about 145 °C, which is below the normal curing temperatures of about 152 °C. Due to their relatively high boiling points (about 163 °C, 290 °C, 309 °C, and 328 °C, respectively), α-methylstyrene (C9H 10 ); 2,3-diphenyl-1-butene (C 16 H 16 ); 1,3-diphenyl-1-butene (C 16 H 16 ); and 1,4-diphenyl-1-butene (C16 H 16 ) when the FRP product is cured at normal curing temperatures of approximately 152 °C.

[0036] Now, however, with reference to Fig. 3, heating the FRP product to a temperature of 152 °C while subjecting the FRP product to a negative pressure of 2.7 hPa (2 mmHg) can effectively decompose styrene (C8H8); α-methylstyrene (C9H 10 ); 2,3-diphenyl-1-butene (C 16 H 16 ); 1,3-diphenyl-1-butene (C 16 H 16 ); and 1,4-diphenyl-1-butene (C 16 H 16 ) from the FRP product. Therefore, the volatile compound extraction process described herein can be used to effectively extract one or more volatile compounds from an FRP product without heating the FRP product above normal processing temperatures.

[0037] Furthermore, the volatile compound extraction process can be performed at relatively low temperatures (e.g., at normal curing temperatures) concurrently with or following other heat treatment steps in the FRP manufacturing or finishing process. For example, the volatile compound extraction process described herein can be performed during or after the curing or partial curing of an FRP product, and also in the same chamber. EXAMPLE 2

[0038] Polymeric adhesives and sealants are commonly used in vehicle body assembly to bond body panels together or to form a seal between body panels or along a seamed portion of a body panel. For example, beads or strips of polymeric adhesives and sealants are often applied between overlapping body panels and along seamed or flanged edge areas of body panels. To adjust the rheological and thixotropic properties of the polymeric adhesives and sealants, solvents and other volatile compounds (e.g., plasticizers) are typically added to the adhesive and sealant precursor compositions. However, residual amounts of these volatile compounds may become trapped in the beads or strips of the adhesive or sealant after curing.The presently disclosed extraction process can be used to effectively reduce or eliminate the amount of residual volatile compounds from a product made with polymeric adhesives and sealants without compromising the structural integrity, dimensional stability, or robustness of the product.

[0039] Fig. Figure 4 illustrates a plot of vapor pressure (mmHg) as a function of temperature (°C) for the following volatile compounds: 2-methyloctane (C9H 20 ) (solid line, 60); 2-methylpentadecane (C 16 H 34 ) (dashed line, 70); and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) (C 16 H 30 O4) (dotted line, 80); at pressures up to 760 mmHg (1 atm, 1013 hPa). The heat of vaporization or enthalpy of vaporization (ΔH vap) of the volatile compounds at their boiling points is shown in the following table. The vapor pressure and latent heat of vaporization for each compound were obtained from Advanced Chemistry Development, Inc. (ACD / Labs): http: / / www.acdlabs.com / resources / i lab / . ΔH vap (kJ / mol) 2-Methyloctan (C9H 20 ) 36,48 2-Methylpentadecan (C 16 H 34 ) 49,48 (C) 16 H 30 O4) 51,87

[0040] As in Fig. 4, when carried out at normal atmospheric pressure (760 mmHg, 1013 hPa), normal curing temperatures (e.g. about 129 °C) cannot evaporate and thus cannot effectively produce 2-methyloctane (C9H 20 ); 2-methylpentadecane (C 16 H 34 ); or TXIB (C 16 H 30 O4) from a product made from these compounds using polymer adhesives or sealants. This is because the normal boiling points of 2-methyloctane (C9H 20 ), 2-methylpentadecane (C 16 H 34 ) and TXIB (C 16 H 30O4) are below 129 °C (ie about 143 °C, 277 °C and 280 °C). However, with reference to Fig. 5, heating the product at a temperature of 129 °C while subjecting the product to a negative pressure of 2.7 hPa (2 mmHg) can effectively evaporate and produce 2-methyloctane (C9H 20 ); 2-methylpentadecane (C 16 H 34 ); and TXIB (C 16 H 30O4) from the product. Therefore, the volatile compound extraction process described herein can be used to effectively extract one or more volatile compounds from a product made with polymeric adhesives and / or sealants without requiring heating the product above normal processing temperatures. In one form, the presently disclosed extraction process can be performed to extract one or more target volatile compounds from a product without extracting all volatile compounds from the product. For example, the presently disclosed process can be performed to extract certain solvent compounds from the product without extracting all plasticizer compounds.

[0041] Furthermore, the volatile compound extraction process can be performed at relatively low temperatures (e.g., at normal curing temperatures) concurrently with or following other heat treatment processes. For example, the volatile compound extraction process described herein can be performed during or after the curing or partial curing of a product manufactured with polymeric adhesives and / or sealants in the same chamber used for curing the adhesives and / or sealants.

Claims

[1] A process for reducing emissions of volatile compounds from a product selected from a body panel or a body-in-white, the process comprising: Positioning a product comprising a polymeric material and a body panel or body-in-white in a chamber; Creating a negative pressure environment with a negative pressure of less than or equal to 6.7 hPa (5 mmHg) within the chamber; Heating the product in the chamber to a temperature equal to or greater than 125 °C but less than or equal to 300 °C, sufficient to evaporate a volatile compound contained in the polymeric material; and withdrawing a gas stream comprising vapors of the volatile compound from the chamber, wherein the withdrawn gas stream is condensed to a liquid phase to produce a liquid condensate comprising the volatile compound. [2] The method of claim 1, wherein the polymeric material comprises at least one polymer or copolymer selected from the group consisting of: acetals; acrylates; acrylonitrile-butadiene-styrene; alkyds; diallyl phthalate; epoxy; fluorocarbons; melamine-formaldehyde; nitrile resins; phenols; polyamides; polyamide-imides; poly(aryl ethers); polycarbonate; polyesters; polyimides; polymethylpentene; polyolefins; polyphenylene oxide; polyphenylene sulfide; polyurethanes; silicones; styrenes; sulfones; urea-formaldehyde; vinyls; and combinations thereof. [3] The process of claim 1, wherein the volatile compound comprises a compound having a normal boiling point of less than 100°C at normal atmospheric pressure. [4] The process of claim 1, wherein the volatile compound comprises a compound having a normal boiling point greater than or equal to 100°C at normal atmospheric pressure and a vapor pressure less than or equal to 6.7 hPa (5 mmHg) at 20°C. [5] A process according to claim 4, wherein the product in step (c) is heated to a temperature below the normal boiling point of the volatile compound. [6] The method of claim 1, wherein the volatile compound comprises an organic compound. [7] The process of claim 1, wherein the product comprises a fiber-reinforced polymer. [8] The process of claim 7, wherein the volatile compound comprises a styrene compound, a negative pressure of less than or equal to 2.7 hPa (2 mmHg) established in the chamber, and heating the product in step (c) at a temperature greater than or equal to 150°C. [9] A method according to claim 1, wherein the polymeric material comprises a polymeric adhesive or sealant. [10] The process of claim 9, wherein the volatile compound comprises an organic solvent, a negative pressure of less than or equal to 2.7 hPa (2 mmHg) established in the chamber, and heating the product in step (c) at a temperature greater than or equal to 125°C.

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