FILTER AND METHOD FOR DEVELOPING A FILTER THAT DECREASES VOLATILE ORGANIC COMPOUNDS OF A VEHICLE

Disclosed is a method for developing a filter suitable for specific volatile organic compounds (VOCs) emitted from a brand new vehicle.

DETAILED DESCRIPTION

Numerous volatile organic compounds (VOCs) are emitted from a brand new vehicle, including acetaldehyde, propionaldehyde, acetic acid, butanol, trimethylamine, butyric acid, hexanol, etc. The kind and concentration of the VOCs vary greatly depending on what materials are used for the interior parts of the brand new vehicle. In general, the VOCs from the brand new vehicle do not cause a severe problem since they are thoroughly controlled during the manufacture of the vehicle. However, when VOCs adsorbed to different parts of the vehicle, such as an evaporator core of an air conditioner, are emitted at once such as during use of the vehicle, they may cause offensive odor and unpleasantness. If a small amount of VOCs is filtered by a filter, the vehicle may be made more pleasant. The present invention provides a filter customized for VOCs, particularly a filter that may be used in any application related to air conditioning. The filter can also be suitable for any product that filters harmful substances, such as a gas mask.

The present invention provides a method for developing a filter for decreasing VOCs, including:

(a) collecting an indoor gas from a brand new vehicle;

(b) analyzing the collected gas;

(d) selecting adsorbent substances for the target VOCs; and

(e) combining the adsorbent substances to provide a filter.

In the step (a), a gas circulating through an air-conditioning system of a brand new vehicle is collected using a method commonly employed in the related art. More specifically, it may be performed by a-1) hermetic sealing three out of the four vehicle air conditioner exhausts, a-2) covering the remaining one exhaust through which air can flow using a glass tube and a vinyl bag, a-3) connecting the opening of the vinyl bag (e.g., a 10-L PE sample bag) to the glass tube and a-4) operating the air conditioner at level 2 under an internal ventilation condition and collecting a gas in the vinyl bag.

In the step (b), the collected gas may be analyzed using the following method and apparatus. Among VOCs, the seven compounds specified as foul odor substances, i.e. styrene, toluene, xylene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), butyl acetate and isobutyl alcohol, may be detected using a Tenax-TA adsorbent tube (Supelco, U.S.A) in which 200 mg or more of a Tenax-TA absorbent is filled. After the collection, the Tenax-TA adsorbent tube may be kept at a temperature of about 4° C. and analyzed by GC/MSMS (3800GC/1200L, Varian, U.S.A). Alternatively, other GC/MS techniques known to those skilled in the art may be used for analysis.

GC/MS analysis data for an indoor gas from a brand new vehicle are given in Table 1. Air conditioner air and indoor air (air from the passenger compartment) from a brand new vehicle were individually collected and analyzed. The brand new vehicle used in the test was specially manufactured for the test.

In Table 1, the detection limit is the lowest concentration that can be detected by smelling. In the step (c), target VOCs which contributed a lot to offensive odor were determined based on their measured concentration as compared to a threshold value, which is a minimum concentration that enables detection of the smell by the human nose. The threshold value varies depending on components of the smell, ranging from very low to very high.

After carrying out sensory evaluation for each substance with a large threshold value, main components were determined by comparing the results for the air conditioner air and the indoor air. Results of carrying out sensory evaluation considering threshold values and determining the VOCs contributing to the odor from the vehicle are given in Table 2.

In Table 2, the threshold value was the detected concentration divided by the detection limit. The threshold values may be an effective means for evaluating the contribution of each substance to the smell of the vehicle. As noted above, the detection limit is the lowest concentration that can be detected by smelling. Thus, the threshold value is a very important factor that is indicative of the intensity of odor.

In the step (d), adsorbent substances for the target VOCs are selected. This can be accomplished, for example, by selecting adsorbent substances having pore sizes similar to the sizes of the determined VOCs and having functional groups capable of chemically binding with the VOCs. At present, a technique of capturing similar substances separately is available. For example, porous adsorbent substances having functional groups which are capable of capturing acetaldehydes and fatty acids may be selected. In the step (e), the a filter is prepared using the combination of selected adsorbent substances. For example, the selected porous adsorbent substances may be provided between a filter paper for filtering dust and a filter paper for attaching the adsorbent substances according to a commonly employed filter preparation method.

An exemplary embodiment of a combination filter for reducing offensive odor was prepared as follows.

A melt-blown nonwoven was laminated with a PP nonwoven (15 g/m2).

Step 2. Binder Treatment

The resulting laminate was bonded with Epoclean® (200 g/m2) and a spunbond nonwoven (70 g/m2) through binder treatment.

The nonwoven laminate was cut to have a designed filter width and bent to have a designed number of grooves.

Step 4. Assembly

Nonwovens were bonded on the filter sample to maintain filter shape and to more completely prevent passage of dust. Although nonwovens were bonded on two sides for a general vehicle filter, nonwovens were bonded on four sides of the filter sample in this example.

Test Example

1) Adsorption of VOCs

Sensory evaluation was carried out first by seven panelists listed in Table 3 (Lee, Kim, Ahn, Kim, Kim, Son and Lim) at a concentration 100 times higher than that detected from a vehicle. After passing through the filter, the odor intensity decreased by 2 or more levels based on the panelist feedback. The same test was repeated 3 times and the results are given in Table 3.

Gas analysis results were as follows.

From Table 4, it was demonstrated that the target gases were removed very effectively.

2) Operation Life

Results of testing long-term gas capturing ability were as follows.

Tests were carried out at concentrations 100 times higher than those detected from a vehicle, as described in Table 5.

A result of injecting gases with 100 times higher concentrations and analyzing by GC/MS at different times is given in Table 6. It was demonstrated that the gas removal ability was maintained for a long period of time.

The present invention provides a method for capturing specific harmful VOCs causing offensive odor rather than undiscriminatingly adsorbing gases. As such, the present method is capable of providing a filter having extended operation life. The present invention also provides an air filter that is very effective for capturing specific VOCs from a brand new vehicle.

The present invention has been described in detail with reference to specific embodiments thereof. However, it will be appreciated by those skilled in the art that various changes and modifications may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.