A disposable filter component, a method for treating air and use of a polymer or copolymer of divinylbenzene

Abstract

The present disclosure relates to a single-use filter component for removing NO2 in an air handling system, the component comprising a polymeric composition as air filtration medium, the polymeric composition comprising a plurality of free vinyl groups, wherein the component allows an end user to inspect the air filtration medium to determine when the filter is exhausted based on a color change from white to yellow, or the component comprises an optical sensor configured to inform the end user of the color change. The present disclosure further relates to a single-use filter component for simultaneously removing NO2 in an air handling system, wherein the component comprises a HEPA filter formed from a polymeric composition comprising a plurality of free vinyl groups. The present disclosure further relates to an air handling system, a method of handling air, and the use of a polymer or copolymer of divinylbenzene for forming an air filtration medium.

Description

[0001] This invention provides a disposable filter component. More specifically, this invention provides a disposable filter component for removing NO2 from an air handling system. This invention also provides an air handling system comprising the aforementioned disposable filter component. Specifically, the disposable filter component comprises a polymer composition as an air filter medium, wherein the polymer composition contains a plurality of free vinyl groups. Furthermore, this invention provides a method of treating air, the method comprising passing NO2-containing air through the disposable filter. This invention also provides use for a polymer or copolymer of divinylbenzene for forming an air filter medium, more specifically, wherein at least 7.0% of the carbon atoms in the polymer or copolymer of divinylbenzene are vinyl carbon atoms. This invention is particularly applicable to air conditioning systems, including both residential air purifiers and industrial HVAC systems, as well as products such as face masks.

[0002] Air pollution is a growing concern in modern society, with devastating negative impacts on the environment and ultimately human health. Data from the World Health Organization (WHO) indicates that nine out of ten people breathe air exceeding WHO guidelines, containing high levels of pollutants, and it is estimated that ambient air pollution causes over four million premature deaths worldwide each year. Pollution is of particular concern in densely populated urban environments, where pollution from industrial processes (such as power generation, agriculture, and waste incineration) and large emissions from motor vehicles burning fuel can create hotspots of very high levels of harmful environmental pollutants. However, household air pollution is another problem, particularly in developing countries. Household air pollution can occur during domestic activities such as cooking or burning fuels (such as wood and coal).

[0003] Air pollutants include gaseous pollutants and particulate (still suspended in the air) pollutants. Particulate matter (PM) typically consists of very small solid or liquid particles, often solid carbon particles (PM2.5) with a diameter of less than 10 micrometers. 10 ), containing fine particles (PM) with diameters of less than 2.5 micrometers and less than 0.1 micrometers, respectively. 2.5 ) and ultrafine particles (PM 0.1 Common sources include internal combustion engines and the combustion of fuels such as wood and coal. Gaseous pollutants and particulate pollutants known to have negative health effects include nitrogen dioxide (NO2), nitric oxide (NO), ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO).

[0004] Despite a long-standing understanding of the problems caused by gaseous pollutants, most filters used for air purification focus on capturing particulate matter. Typically, filters are made of different layers of porous media, which may vary in thickness depending on the end application and the minimum size of the particulate matter to be filtered. These layers are usually made of glass fiber or polymers.

[0005] NO2 and particulate matter are significant pollutants produced by road emissions, specifically by the combustion of fuel in internal combustion engines. Road traffic is a major outdoor source of nitrogen dioxide. Therefore, those living near busy roads are particularly exposed to and affected by NO2 pollution. Additionally, NO2 can also be produced from internal sources such as cooking and heating. Long-term exposure to NO2 can lead to decreased lung function. Even short-term exposure has evidence that NO2 can increase the risk of bronchitis and asthma. NO2 can cause airway inflammation and increase susceptibility to respiratory infections and allergens.

[0006] However, the need to control NO2 levels in the environment means that effective air filters capable of filtering harmful gaseous pollutants such as NO2 are still required.

[0007] As is well known, filters can further include adsorbents or catalysts to remove gaseous pollutants such as volatile organic compounds, carbon monoxide, and nitrogen dioxide. Activated carbon is a commonly used adsorbent / catalyst, and its adsorption of NO2 has been extensively studied in recent decades. However, nitrogen dioxide escape can easily increase over time. Furthermore, activated carbon can reduce nitrogen dioxide to provide nitric oxide (NO), another pollutant. Activated carbon cannot bind NO2 or NO tightly, therefore it cannot adequately absorb pollutants to remove them from the air. Naturally, it is preferable to filter nitrogen dioxide from the air without generating other nitrogen oxides (primarily NO). Since air pollutants are often invisible to the naked eye (at least at background levels) and activated carbon is assumed to remain essentially black, it is impossible for end users to visually determine when the adsorbent is underperforming or depleted. Some commercial air purifiers are equipped with sensors that alert users to increased pollutant concentrations in the ambient air. The adsorption capacities of many other materials (such as zeolites, metal-organic frameworks (MOFs), and metal oxides (such as Al2O3 and TiO2) (both doped and undoped) have been studied, but none have the efficiency required for use in air filters to remove NO2. However, some air purifiers incorporate other materials (such as zeolites or alumina, as well as activated carbon).

[0008] For decades, it has been known that polymers can react with gaseous pollutants such as NO2. For example, Jellinek and Flagsman studied the reaction of nitrogen dioxide with polystyrene films in the *Journal of Polymer Science*, Part A-1, Vol. 7, pp. 1153–1168 (1969). Shortly afterward, Grubner et al. studied the reaction of nitrogen dioxide with polystyrene films in the *American Industrial Hygiene Association Journal*, 33:4, pp. 201–206, in their paper "Collection of Nitrogen Dioxide by Porous Polymer Beads". Q's reactivity. Q is a crosslinked polymer of ethylvinylbenzene and divinylbenzene, primarily used in HPLC columns. WO 2017 / 160646A1 discloses an air filter comprising a polymeric adsorbent for reactive gases. The disclosed reactive gases are hydrogen fluoride, fluorine, hydrogen bromide, bromine, hydrogen chloride, chlorine, sulfuric acid, sulfurous acid, hydrogen sulfide, sulfur dioxide, nitric acid, nitrous acid, nitrogen dioxide, or mixtures thereof. The polymeric adsorbent comprises (i) a reaction product of a precursor polymeric material and (ii) a nitrogen-containing compound, the precursor polymeric material comprising a polymerizable composition containing 8 wt% to 65 wt% maleic anhydride, 30 wt% to 85 wt% divinylbenzene, and 0 wt% to 40 wt% a styrene-type monomer, the nitrogen-containing compound being selected from ammonia or compounds having at least one primary or secondary amino group. This disclosure focuses on the removal of sulfur dioxide (SO2), removing reactive gases generated by reactions with amino groups present in the polymeric adsorbent.

[0009] Therefore, there is a need in the art for components in air handling systems that effectively remove NO2 from the air and allow end users to easily determine when the adsorbent material is depleted and needs replacement. The inventors developed this invention to overcome the problems in the prior art.

[0010] Therefore, in a first aspect, a disposable filter component for removing NO2 from an air handling system is provided, the component comprising a polymer composition as an air filter medium, the polymer composition containing a plurality of free vinyl groups.

[0011] This component allows the end user to inspect the air filter media to determine when the filter is depleted based on a color change from white to yellow, or the component includes an optical sensor configured to notify the end user of the color change.

[0012] This disclosure will now be described further. In the following paragraphs, different aspects / implementations of this disclosure are defined in more detail. Unless expressly stated to the contrary, each aspect / implementation so defined may be combined with any other aspect / implementation or multiple aspects / implementations. Specifically, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous, or one or more other features.

[0013] This invention relates to a single-use filter element for removing NO2 from an air handling system. "Single-use" means that the filter element is intended for use without regeneration and can be replaced with a replacement component once the filter element has reached the end of its service life. This can be determined as described herein. Furthermore, "single-use" should not be construed as limited to use in one instance, but rather as a single-use application. Therefore, a "single-use" filter can retain its NO2 adsorption capacity after being put into use by the end user. For example, an air conditioning system or air purifier can be turned on and off to actively pass air through the "single-use" filter element in various situations.

[0014] This component is part of an air handling system. Preferably, the component is a replaceable part of the air handling system. In other words, for example, in an air purifier, once the filter component is depleted, the component of the present invention can be removed by the end user and replaced with a new filter component. In another example, a mask (such as a respirator) may include a removable filter component. Alternatively, the component may be integrated into the air handling system. Generally, this is preferred when the air handling system is disposable, considering the cost of disposing of the entire system. For example, the air handling system may be a disposable mask including an integrally formed disposable filter component.

[0015] When installed in an air handling system, the filter element as described herein is suitable for removing NO2. An air handling system refers to any type of equipment or apparatus in which a filter element is provided to a flow of air to be treated to remove NO2.

[0016] The filter component comprises a polymer composition as an air filter medium. Specifically, the polymer composition contains a plurality of free vinyl groups. The inventors have discovered filter components comprising an air filter medium formed from a polymer composition containing a plurality of free vinyl groups, which exhibit advantageous selectivity in adsorbing NO2 from the air. Specifically, the inventors believe that NO2 reacts with the free vinyl groups and can therefore be considered as chemisorption. "Free vinyl groups" refers to polymer compositions containing R-CH=CH2 groups. The polymer composition can be obtained by reacting monomers containing alkenyl groups (i.e., those containing carbon-carbon double bonds) (such as vinyl groups) in an addition polymerization reaction to form a single-bonded carbon backbone. Thus, the free vinyl groups are those that are unreacted. As described herein, the inventors have found that divinylbenzene is a particularly preferred monomer that can be polymerized to produce a polymer in which a portion of the vinyl groups are unreacted for polymerization or crosslinking.

[0017] The component of this invention allows the end user to inspect the air filter media to determine when the filter is depleted. The end user can determine when the filter is depleted based on a color change from white to yellow. Alternatively, the component includes an optical sensor configured to notify the end user of the color change and therefore the need to replace the filter. The optical sensor may be configured to provide an output, for example, once reflected light of a specific wavelength is observed (i.e., light that is yellow enough to indicate depletion of NO2 removal performance).

[0018] Therefore, the filter component can take any form known in the art, as long as it has a means to allow the end user to be aware of the color change. In one embodiment, the component may include a frame (such as a peripheral frame) or a housing. The component may preferably take the form of a filter cartridge made of injection-molded rigid plastic. Such a filter cartridge may be designed to be fitted into an air filtration system (such as an air conditioner). In any case, the component contains air filter media and may include a re-openable opening that allows the user to directly observe the air filter media. Preferably, the opening in the component may be a screen or mesh that includes holes sufficient to contain the air filter media but allowing visual inspection. In another embodiment, the component may include an optically transparent portion (e.g., a transparent window) to allow inspection of the air filter media held within the component. In such embodiments, instead of the end user actively inspecting for color changes, an external optical sensor may be used to detect such color changes and notify the end user. Such an external optical sensor may be part of an air handling system in which the filter component is installed, rather than the filter component itself.

[0019] The inventors have discovered that by providing a polymer composition as an air filter medium having multiple free vinyl groups, nitrogen dioxide can react with the vinyl groups to produce a yellow product. Therefore, the inventors have found that by increasing the number of vinyl groups in the polymer, the color change is more pronounced, and simultaneously, the amount of NO2 that can be adsorbed is greatly increased. Therefore, the present invention does not require, and preferably does not require, that the polymer composition omits a separate colorimetric indicator (such as a pH indicator), for example, methyl red. In other words, the color change from white to yellow is entirely due to the chemisorption of NO2 by the polymer composition, which is a result of the reaction of multiple free vinyl groups with NO2.

[0020] In an alternative preferred embodiment, the component includes an optical sensor capable of detecting color changes from white to yellow and notifying the user once a sufficient color threshold has been reached. This is particularly preferred for air conditioning and air purification systems that can be installed in locations that are harder for users to access, such as in industrial HVAC systems.

[0021] Where the component allows for visual inspection, it preferably includes a yellow marking to allow the end user to compare it with the air filter media and thereby determine when the filter is depleted. Thus, once the color and marking of the air filter media match, the filter component of the present invention allows the end user to replace the filter containing the air filter media with a new filter component, and / or otherwise dispose of the depleted filter, such as when the filter component is part of a disposable face mask.

[0022] As will be understood, the precise point at which the color change indicates the filter has achieved depleted NO2 removal performance will depend on the selected filter medium. When a polymer has more free vinyl groups per unit weight, the intensity of the final color can be a darker yellow than a polymer with fewer free vinyl groups. Therefore, those skilled in the art can easily select the desired endpoint based on the chosen polymer and conventional testing. For example, the polymer can be tested to observe when the NO2 level in the treated test gas begins to rise, and the polymer's color can then be set to provide an endpoint or replacement point.

[0023] In one embodiment, the component further includes activated carbon downstream of the polymer composition. Because activated carbon can be used to adsorb other contaminants such as volatile organic compounds, fragrances, gaseous household chemicals, and many other gases, it is a preferred additional material for filter components, particularly for air conditioning systems. The inventors have discovered that by providing activated carbon downstream of the polymer composition, NO2 can be selectively adsorbed before contacting the activated carbon, where NO2 might otherwise be reduced to form NO. As will be understood, downstream refers to the location of the activated carbon relative to the direction in which the air to be treated moves through the filter during use. Downstream is used to refer to the location where the air to be treated subsequently arrives, such that the air first passes through the polymer composition and then through the activated carbon. This configuration minimizes or prevents the formation of NO on the activated carbon and releases the activated carbon's ability to treat contaminants other than NO2.

[0024] Preferably, the air filter medium is provided in the form of a plurality of beads retained within the component. The beads are substantially spherical and can be provided with an average particle size (d) preferably in the range of 100 μm to 1600 μm, preferably 300 μm to 1200 μm. 50 These beads can be, for example, held between mesh screens.

[0025] Preferably, the air filter medium has a density of at least 600m. 2 The surface area is approximately 700 m² / g. Such a high surface area allows for the efficient extraction of NO2 from the air, a pollutant typically present in relatively low concentrations (e.g., less than 1 ppm in ambient air). Surface area can also be referred to as BET specific surface area, which is the total surface area per unit mass (or volume) of porous polymer; such measurements are routine in the art and are typically measured via nitrogen adsorption. Preferably, the surface area is at least 700 m² / g. 2 / g, more preferably 750m 2 / g to 2000m 2 / g.

[0026] In one embodiment, the polymer composition may be loaded onto fibers. For example, the polymer composition may be loaded onto a loosely woven fabric, typically made of cotton. The polymer composition may also be loaded onto yarn, a material that can simultaneously adsorb the pollutant formaldehyde.

[0027] In another embodiment, the polymer composition itself may be provided in the form of a woven or nonwoven fabric, with fibers formed from the polymer composition. Preferably, the polymer composition is melt-blown to form a nonwoven sheet as an air filtration medium. Even more preferably, the polymer composition may be provided in the form of a HEPA filter. HEPA filters are well known in the art and are required to be able to filter at least 99.95%, preferably greater than 99.97%, of particles with a diameter equal to or greater than 0.3 μm. Thus, HEPA filters can physically capture and filter particles larger than 0.3 μm, including microorganisms (such as bacteria and viruses), dust, and aerosols, while adsorbing gaseous NO2 from the air. To prevent back pressure buildup, HEPA filters need to be replaced over time. The simultaneous color change resulting from the reaction with NO2 is used to indicate to the user when the filter is depleted and needs replacement.

[0028] Since existing filters may already include HEPA filters upstream of activated carbon filters, providing the NO2 treatment polymer itself as a HEPA filter is highly desirable. This is because there are no additional components to increase back pressure. This is especially important in air conditioning systems where back pressure limits are critical.

[0029] Another aspect of the invention provides a disposable filter component for simultaneously removing NO2 from an air handling system, wherein the component comprises a HEPA filter formed of a polymer composition containing a plurality of free vinyl groups. HEPA filters are well known and are typically replaced periodically without inspection based on the expected lifespan of the filter in a given application. Therefore, the filter of this other aspect is used to simultaneously remove NO2 from the filtered air. Considering the frequent, periodic replacement of the HEPA filter to ensure continuous and effective particulate filtration, the user does not need to inspect for color changes caused by NO2 adsorption.

[0030] The polymer composition contains a plurality of free vinyl groups. As described herein, the inventors have discovered that the presence of free vinyl groups and unreacted vinyl groups can be used to react with NO2 to effectively remove NO2 from the air, while causing the color of the polymer composition to change from white to yellow. As described herein, this can be achieved through... 13 C solid-state nuclear magnetic resonance (C 13 The presence of free vinyl groups in polymer compositions can be readily determined by C-SSNMR spectroscopy.

[0031] Particularly preferred is that the polymer composition is a hydrocarbon, i.e., composed of hydrogen and carbon. In other words, the polymer composition is preferably a polymerization product of a hydrocarbon precursor. The absence of additional functional groups in hydrocarbon polymers makes them relatively inert to many pollutants and also hydrophobic, making them particularly suitable for the selective adsorption of NO2. To incorporate free vinyl groups into the final polymer, preferably at least one precursor contains two vinyl groups, such that one vinyl group is incorporated into the polymer backbone during polymerization, while the other vinyl group remains unpolymerized and thus free. Therefore, divinylbenzene is a particularly preferred precursor, i.e., a particularly preferred monomer for polymerization. Thus, the polymer composition preferably comprises a polymer or copolymer of divinylbenzene. Even more preferably, the polymer composition consists of a polymer or copolymer of divinylbenzene. Divinylbenzene generally refers to a mixture of its para- and meta-isomers, as such isomer mixtures are the most common commercially available form.

[0032] Polymers and copolymers of divinylbenzene (DVB) are known and frequently used as porous polymer adsorbents in chromatography. Divinylbenzene polymers and copolymers possess particularly high surface areas ranging from mesoporous to microporous, allowing for efficient interaction between air and the polymer. While polymers and copolymers of DVB are known, DVB with two vinyl groups is used as a crosslinking agent during polymerization to link the two polymer chains during polymer growth rather than providing free vinyl groups. Therefore, the resulting polymer may not contain free vinyl groups. Common copolymers are obtained by polymerizing styrene with divinylbenzene (i.e., styrene-divinylbenzene).

[0033] The inventors have discovered that the number of free vinyl groups in the resulting polymer or copolymer can be increased by polymerizing monomers containing at least two vinyl groups and / or by increasing the concentration of such monomers in the polymerizable composition prior to polymerization. Therefore, the polymer composition is preferably a polymer of a polymerizable composition containing at least 60 wt% of monomers containing at least two vinyl groups. Even more preferably, the polymerizable composition contains at least 70 wt%, at least 80 wt%, at least 85 wt%, or at least 90 wt% of monomers containing at least two vinyl groups. Thus, when the polymer composition comprises or consists of a polymer or copolymer of divinylbenzene, the polymer composition is a polymer of a polymerizable composition containing at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 85 wt%, or at least 90 wt% divinylbenzene. Preferably, the polymer composition comprises a polymer of divinylbenzene, i.e., essentially a polymer of divinylbenzene. However, divinylbenzene with a purity close to 100% is difficult to obtain and may be relatively expensive. For this reason, at least 80 wt% divinylbenzene is particularly preferred for forming copolymers of divinylbenzene. In another embodiment, monomers having at least three vinyl groups (such as trivinylbenzene) can be used for polymerization. However, divinylbenzene is generally readily available commercially and is also a relatively inexpensive monomer for polymerization, thus reducing the cost of disposable filter components.

[0034] Preferably, the polymer composition comprises a copolymer of divinylbenzene and optionally substituted styrene (typically styrene and / or alkyl-substituted styrene, preferably styrene and / or ethylstyrene (i.e., ethylvinylbenzene)). Like divinylbenzene, alkylstyrene and ethylstyrene typically refer to mixtures of p-alkylstyrene and m-alkylstyrene, and p-ethylstyrene and m-ethylstyrene, respectively. Therefore, the polymer composition is preferably a polymeric product of a polymerizable composition substantially consisting of divinylbenzene and optionally substituted styrene (preferably styrene and / or ethylstyrene). Such compositions are commercially available as “divinylbenzene” because the divinylbenzene precursor is typically obtained only in relatively low purities (e.g., at least 50% by weight). Divinylbenzene is commercially produced typically by the thermal dehydrogenation of isomeric diethylbenzene. Commercially available divinylbenzene with a purity of at least 80% by weight is particularly suitable, given the desired increase in the number of free vinyl groups, as the remaining 20% ​​by weight is typically a mixture of styrene and ethylstyrene, along with unavoidable impurities. In commercially available divinylbenzene, some unavoidable impurities (such as naphthalene) may remain from the cyclization of o-divinylbenzene, although virtually all naphthalene can be easily isolated.

[0035] In another embodiment, the polymer composition may comprise methacrylates (such as methyl methacrylate) and divinylbenzene as discussed above, and optionally copolymers of styrene and / or alkylstyrene. Such polymer compositions may be obtained by polymerizing commercially available divinylbenzene with methacrylates.

[0036] Suitable divinylbenzene copolymers for use as air filter media according to the present invention include those available from […]. of VP OC 1065 (a copolymer of amine-functionalized styrene and DVB) and available from Mitsubishi Chemical Corporation HP20 is a copolymer of DVB and styrene. Q is a copolymer of ethylvinylbenzene and divinylbenzene. In a particularly preferred embodiment, the polymer composition is commercially available. of PAD1200 is a copolymer that can be polymerized from commercially available divinylbenzene and its associated impurities (such as ethylstyrene). Due to the incomplete polymerization of a large amount of divinylbenzene in the polymerizable composition used, PAD1200 provides a particularly high amount of free vinyl groups.

[0037] The polymer compositions used in this invention provide a plurality of free vinyl groups for reaction with NO2 from an air stream containing NO2. The number of free vinyl groups can be determined by... 13 C SSNMR spectroscopy is used for quantification. Regardless of the precursors and / or monomers used to form the polymer composition, preferably at least 5.0% of the carbon atoms in the polymer composition are vinyl carbon atoms, preferably at least 5.5%, at least 6.0%, at least 6.5%, at least 7.0%, and even more preferably at least 7.5% of the carbon atoms are vinyl carbon atoms. The concentration of such vinyl groups provides the desired strong color change from white to yellow, and as the number of vinyl carbon atoms decreases to below about 5.0%, the color change and the ability to adsorb NO2 gradually weaken.

[0038] In cases where the polymer composition contains a polymer or copolymer of divinylbenzene, the inventors have discovered that free vinyl groups... 13 A peak is generated at approximately 112 ppm in the C SSNMR spectrum (corresponding to the unsubstituted carbon of the vinyl group, i.e., -CH=). C H2). In any case, by 13 By comparing the C SSNMR spectrum with the spectrum of the polymer obtained from the reaction with bromine, peaks generated by vinyl groups can be easily identified. Bromine (Br2) reacts with free vinyl groups, and the peaks originating from these groups are readily identifiable. 13The vinyl carbon peaks in the aromatic region of the CSSNMR spectrum disappear. The total vinyl content of the polymer composition can then be quantified using the relative intensity of the vinyl carbon peaks (double the intensity value to indicate two carbon atoms in the vinyl groups). The inventors have found that PAD1200 contains approximately 3.8% unsubstituted vinyl carbon atoms, which corresponds to approximately 7.6% vinyl carbon atoms in the polymer composition relative to the total number of carbon atoms. The inventors have found... Q is a copolymer of ethyl styrene in greater quantities than PAD1200, as evidenced by larger peaks (approximately 15 ppm and 29 ppm) in the aliphatic region of the spectrum. Q produces an unsubstituted vinyl carbon peak with an intensity of about 3.2% at about 112 ppm (corresponding to a vinyl carbon content of about 6.4%).

[0039] 13 C10 SSNMR spectra were obtained using Topspin 4.0 software on the Bruker Avance Neo console at 14.1T (ν0 ( 1 It was obtained under a static field strength of H) = 600MHz. For 13 C. The probe is tuned to 150.94 MHz and referenced to alanine CH3 at 20.5 ppm. The powdered sample can be loaded into a zirconia MAS rotor with a Kel-F cap, providing sample mass before and after weighing. The sample mass can be from approximately 30 mg to approximately 60 mg. The rotor can be rotated using room temperature purified compressed air. The number of scans can be 1024, with D1 set to 30.0 s. 13 Such parameters are typical in the field of C SSNMR spectroscopy.

[0040] As will be understood, it has the molecular formula C 10 H 10Divinylbenzene contains four vinyl carbon atoms, two of which will form part of the polymer backbone for inclusion in the final polymer. Therefore, the maximum free vinyl group content of pure divinylbenzene in which only one vinyl group is polymerized is 20.0%. Thus, a polymer or copolymer of divinylbenzene containing at least 7.0% vinyl carbon atoms is obtained by keeping at least 35% of the second vinyl groups unreacted during polymerization. During polymerization, as the crosslinking level increases due to the polymerization of two vinyl groups of the same monomer, configuration fixation prevents further polymerization of the second vinyl groups of adjacent monomer units, thereby leaving the vinyl groups free in the resulting polymer. Therefore, as described herein, the polymer composition preferably comprises a copolymer formed from at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 85 wt%, or at least 90 wt% of monomers having at least two vinyl groups (most preferably divinylbenzene).

[0041] According to another aspect, an air handling system is provided that includes a disposable filter as described herein. Preferably, the air handling system is an automotive air conditioning system. This is particularly useful because the filter is used in systems that encounter high levels of NO2, where the system is routinely inspected and replaced during its service life.

[0042] Once the filter component is depleted, as determined by the user's observation that the polymer composition has turned yellow, it can be replaced. Alternatively, an optical sensor can be configured to warn the user of a color change. In such embodiments, a warning light in the control panel of the vehicle's dashboard can be used to warn the user of a color change in the filter, and thus alert the user that the filter is depleted and needs replacement. Alternatively, in embodiments where the polymer is in the form of a HEPA filter, the filter can be replaced simply as part of routine servicing of the vehicle's air conditioning system.

[0043] According to another aspect, a method for treating air to remove NO2 is also provided, the method comprising passing NO2-containing air through a disposable filter as described herein.

[0044] In another aspect, there is provided the use of a divinylbenzene polymer or copolymer for forming an air filter medium, wherein at least 7.0% of the carbon atoms in the divinylbenzene polymer or copolymer are vinyl carbon atoms, as described by... 13The results were determined by C SSNMR. Although commercially available polymers and copolymers of divinylbenzene are known, they are sold for applications such as the purification of biological materials (such as small peptides and proteins), wastewater treatment, chemicals, decolorization of sugar solutions and / or stevia, or chromatographic columns. The inventors have determined that such polymers and copolymers are particularly suitable for forming air filter media suitable for removing NO2 from the air. Attached Figure Description

[0045] The invention will now be further described with reference to the following non-limiting drawings, in which:

[0046] Figure 1 This is a graph comparing NO2 escape and NO generation over time for commercially available activated carbon and polymer PAD610.

[0047] Figure 2 This indicates the structure of a styrene-divinylbenzene copolymer that does not contain free vinyl groups.

[0048] Figure 3 This represents the structure of an ethylstyrene-divinylbenzene copolymer having multiple free vinyl groups.

[0049] Figure 1 This is a comparison between the polymer composition described herein for disposable filter components and commercially available activated carbon compositions for use in home air purifiers. Figure 1 The results are shown when air with approximately 40% relative humidity and 400 ppb NO2 is passed through the test sample at room temperature (22°C). Figure 1 The study showed a rapid increase in NO2 escape from activated carbon, while the polymer PAD610 (a polymethacrylate crosslinked with DVB and having multiple free vinyl groups) maintained low levels of NO2 escape over 90 hours. Advantageously, the polymer composition did not result in any significant level of NO production, while NO production was closely correlated with the amount of NO2 escape from the activated carbon and rapidly increased to over 40 ppb.

[0050] Figure 2 This represents the structure of a styrene-divinylbenzene copolymer without free vinyl groups. Divinylbenzene is used to crosslink the polymer backbone of styrene. On the other hand, Figure 3 The structure of a copolymer of ethylstyrene and divinylbenzene is indicated, such as that it can be obtained by polymerization of commercially available divinylbenzene having a purity of at least 80% by weight, with the remainder being essentially ethylstyrene. Although Figure 3 The structures shown include para-substituted benzene rings, but it should be understood that copolymers may include a mixture of meta- and para-substituted compounds. Figure 3The copolymer shown can be obtained by polymerizing commercially available divinylbenzene and exhibits better performance than... Figure 2 The contrast copolymer showed significantly more crosslinking. This increased crosslinking during polymerization resulted in some vinyl groups remaining unpolymerized and free within the resulting polymer.

[0051] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural references. The use of the term “comprising” is intended to be interpreted as including such features but not excluding other features, and also to include feature options that must be limited to those features described. In other words, the term also includes the limitations “consistently made of” (intended to indicate that certain additional components may be present, provided that they do not substantially affect the essential characteristics of the described feature) and “consisting of” (intended to indicate that other features may be excluded such that if these components were expressed as percentages of their proportions, they would total 100%, taking into account any unavoidable impurities), unless the context clearly indicates otherwise.

[0052] The detailed description above has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments shown herein will be apparent to those skilled in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A disposable filter component for removing NO2 from an air handling system, the component comprising a polymer composition as an air filter medium, the polymer composition comprising a polymer or copolymer of divinylbenzene, wherein the polymer composition comprises a plurality of free vinyl groups, and wherein at least 7.0% of the carbon atoms in the polymer composition are vinyl carbon atoms, through... 13 Measured by C SSNMR, and The aforementioned component allows the end user to inspect the air filter media to determine when the filter is depleted based on the color change of the polymer composition from white to yellow, wherein the color change from white to yellow is entirely caused by the chemisorption of NO2 on the polymer composition as a result of the reaction of the plurality of free vinyl groups with NO2.

2. The disposable filter component of claim 1, wherein the component includes at least an optically transparent portion to allow inspection of the air filter medium held within the component.

3. The disposable filter component according to any one of claims 1 or 2, wherein the air filter medium is provided in the form of a plurality of beads held within the component.

4. The disposable filter component according to any one of claims 1 or 2, wherein the air filter medium is provided in the form of a woven or nonwoven fabric.

5. The disposable filter component of claim 4, wherein the air filter medium is provided in the form of a HEPA filter.

6. The disposable filter component according to any one of claims 1 or 2, wherein the air filter medium has a density of at least 600 m³. 2 / g of surface area.

7. The disposable filter component according to any one of claims 1 or 2, the disposable filter component further comprising a yellow marking for allowing the end user to compare with the air filter media to determine when the filter is depleted.

8. The disposable filter component according to any one of claims 1 or 2, wherein the polymer composition is a polymeric product comprising at least 80% by weight of a polymerizable composition of divinylbenzene.

9. The disposable filter component according to any one of claims 1 or 2, wherein the component further comprises activated carbon downstream of the polymer composition.

10. An air handling system comprising a disposable filter according to any one of claims 1 to 9, wherein the air handling system is an automotive air conditioning system.

11. A method for treating air to remove NO2, the method comprising: The air containing NO2 is passed through a disposable filter according to any one of claims 1 to 9.

Images