U.S. patent application number 16/610950 was filed with the patent office on 2020-02-27 for heat exchanger.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO. The applicant listed for this patent is DENSO CORPORATION, KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO. Invention is credited to Hirofumi FUTAMATA, Sayuri HASHIMOTO, Takayuki HIROSE, Hiroshi ITO, Satoru KOSAKA, Atsushi MURASE, Kenji NAKAMURA, Tomohide NISHINO, Kiyomi SAKAKIBARA, Kazuhisa UCHIYAMA.
Application Number | 20200064086 16/610950 |
Document ID | / |
Family ID | 64740596 |
Filed Date | 2020-02-27 |
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United States Patent
Application |
20200064086 |
Kind Code |
A1 |
ITO; Hiroshi ; et
al. |
February 27, 2020 |
HEAT EXCHANGER
Abstract
A heat exchanger having a polyamine on at least part of a
surface of the heat exchanger. The existence of polyamine on the
surface of the heat exchanger allows the odor components to be
temporality held by virtue of the action of polyamine, and the odor
components are not released into an interior room or the like at
once in conjunction with the evaporation of free water (such as
condensed water). Thus, the release of odor components is made
moderate, and changes in the concentration of odor components in
the interior room are reduced, so that strong odors sensed by
people are suppressed. A typical example of the polyamine is PEI,
and a typical example of the heat exchanger is an evaporator used
in a car air-conditioner.
Inventors: |
ITO; Hiroshi; (Nagakute-shi,
JP) ; KOSAKA; Satoru; (Nagakute-shi, JP) ;
SAKAKIBARA; Kiyomi; (Nagakute-shi, JP) ; MURASE;
Atsushi; (Nagakute-shi, JP) ; NAKAMURA; Kenji;
(Kariya-city, JP) ; HIROSE; Takayuki;
(Kariya-city, JP) ; UCHIYAMA; Kazuhisa;
(Kariya-city, JP) ; NISHINO; Tomohide;
(Kariya-city, JP) ; HASHIMOTO; Sayuri;
(Kariya-city, JP) ; FUTAMATA; Hirofumi;
(Kariya-city, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOYOTA CHUO KENKYUSHO
DENSO CORPORATION |
Nagakute-shi, Aichi
Kariya-city, Aichi |
|
JP
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOYOTA CHUO
KENKYUSHO
Nagakute-shi, Aichi
JP
DENSO CORPORATION
Kariya-city, Aichi
JP
|
Family ID: |
64740596 |
Appl. No.: |
16/610950 |
Filed: |
April 13, 2018 |
PCT Filed: |
April 13, 2018 |
PCT NO: |
PCT/JP2018/015457 |
371 Date: |
November 5, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60H 1/00335 20130101;
F25B 39/02 20130101; F25B 1/00 20130101; B60H 3/0092 20130101; F28F
19/04 20130101; F28F 2245/00 20130101; F28F 13/18 20130101 |
International
Class: |
F28F 13/18 20060101
F28F013/18; F25B 39/02 20060101 F25B039/02; F28F 19/04 20060101
F28F019/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2017 |
JP |
2017-126774 |
Claims
1. A heat exchanger having a polyamine on at least part of a
surface of the heat exchanger.
2. The heat exchanger as recited in claim 1, wherein the polyamine
has a molecular weight of 300 to 70,000.
3. The heat exchanger as recited in claim 1, wherein the polyamine
has a distance of 2 to 4 .ANG. between adjacent amino groups.
4. The heat exchanger as recited in claim 1, wherein the polyamine
includes a hydrated layer having a thickness of 20 to 90 nm.
5. The heat exchanger as recited in claim 1, wherein the polyamine
is a polymer having one or more types of functional groups selected
from a carbonyl group, a carboxyl group, an imide group, a hydroxyl
group, a nitrile group, a nitro group, a sulfide group, a sulfoxide
group, a sulfone group, a thiol group, or an ester group.
6. The heat exchanger as recited in claim 1, wherein the polyamine
comprises at least polyethylenimine (PEI).
7. The heat exchanger as recited in claim 1, wherein the heat
exchanger is an evaporator.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger that can
suppress odors sensed by people in an interior room or the
like.
BACKGROUND ART
[0002] Interior rooms of buildings, moving vehicles, etc. are
usually provided with air-conditioning apparatuses (referred to as
"air conditioners"). Air conditioners introduce air having passed
through heat exchangers into interior rooms to adjust the
temperature and humidity in the interior rooms.
[0003] People in such interior rooms may sense odors even when a
strong odor source is not present. Causes of such odors may often
be odor components released at certain timing from air conditioners
(in particular, from built-in heat exchangers) in addition to odor
components released from wall surfaces and the like.
[0004] Countermeasures against such odors (deodorization measures,
odor suppression measures) have been adopted, including removal of
odor components causing the odors, such as by adsorption,
decomposition, or washing. In addition, in the case of a member
(apparatus) that generates a large amount of condensed water on the
surface, such as an evaporator for an air conditioner, it has also
been proposed to perform surface treatment with a treatment agent
(such as (modified) polyvinyl alcohol) that has low affinity with
odor substances (odor components) and excellent hydrophilicity.
Descriptions relevant to this are found, for example, in the
following patent documents.
PRIOR ART DOCUMENTS
Patent Documents
[0005] [Patent Document 1] JP2002-285139A [0006] [Patent Document
2] JP2002-285140A [0007] [Patent Document 3] JP2003-3282A [0008]
[Patent Document 4] JP2004-293916A
SUMMARY OF INVENTION
Technical Problem
[0009] When using an evaporator subjected to hydrophilic treatment
as disclosed in the above patent documents, the odor components
absorbed on the surface are washed away with the condensed water,
and the odor components are less likely to accumulate on the
surface of the evaporator. In reality, however, even when an
evaporator subjected to such surface treatment is used, people may
be able to sense odors at certain timing during the operation of
the air conditioner. Thus, the conventional deodorization measures
have not necessarily been sufficient.
[0010] The present invention has been made in view of such
circumstances and an object of the present invention is to provide
a heat exchanger capable of deodorization or odor suppression by
means of a scheme (mechanism) different from conventional ones.
Solution to Problem
[0011] As a result of intensive studies to achieve the above
object, the present inventors have newly found that existence of
polyamine on the surface of a constitutional material (Al alloy
sheet) of a heat exchanger can suppress the odors sensed by people.
Developing this achievement, the present inventors have
accomplished the present invention as will be described
hereinafter.
Heat Exchanger
[0012] (1) The present invention provides a heat exchanger having a
polyamine on at least part of a surface of the heat exchanger.
[0013] (2) Existence of polyamine on at least part of the surface
of the heat exchanger allows people not to sense odors caused by
the heat exchanger in a space in which the air having passed
through the heat exchanger can be introduced. The mechanism for
obtaining such an effect can be considered as follows at present
from the studies on the present invention.
[0014] First, people detect even very low-concentration substances
(odor components) by smell and sense "odors." However, the human
nose tends to sense odors strongly when the amount (concentration)
of odor components or the quality (ratio of each odor component
mixed) has changed, rather than sensing the intensity of odors in
response to the absolute amount (concentration) of odor
components.
[0015] Next, in the case of heat exchangers, the release
(evaporation) of water plays a large role in the release of odor
components. In addition, many of the released odor components are
often those absorbed into the water existing on the surface of the
heat exchanger from the atmosphere, or the like.
[0016] Based on such knowledge and the results of an evaluation
test, which will be described later, the polyamine existing on the
surface of the heat exchanger temporarily holds the odor components
and water to suppress the release thereof and suppresses sudden
release of the odor components into an air-conditioned interior
room (i.e., releases the odor component slowly). It can thus be
considered that, as a result, people in the air-conditioned
interior room are less likely to sense the odors caused by the heat
exchanger.
Others
[0017] (1) In the heat exchanger of the present invention, it
suffices that the polyamine exists at least on the surface side,
and the existence form of the polyamine on the surface of the heat
exchanger is not limited. In a general form, the polyamine may
often be contained in a polymer film that coats the surface of the
heat exchanger. In this case, the polymer film may be composed of a
simple substance of polyamine or may also contain a polymer, a
resin, a metal, and the like other than the polyamine.
[0018] The polyamine as referred to in the present invention may be
modified, and part of the terminal groups may be substituted with
one or more types of polar functional groups such as a carbonyl
group, a carboxyl group, an imide group, a hydroxyl group, a
nitrile group, a nitro group, a sulfide group, a sulfoxide group, a
sulfone group, a thiol group, and an ester group. The polyamine
according to the present invention may be a mixture of two or more
types of polymers (high molecules), and one or more types thereof
may have a graft polymerization structure.
[0019] The polyamine preferably has a chelate structure.
Coordination of metal ions can give antiseptic and antibacterial
properties and other appropriate properties to the heat exchanger.
It is also preferred that the surface of the heat exchanger be
given a hydrophilic property. The polyamine itself may exhibit the
hydrophilic property, or the polyamine may cooperate with one or
more other polymers (high-molecular materials) to give the
hydrophilic property to the surface of the heat exchanger.
[0020] (2) Unless otherwise stated, a numerical range "x to y" as
referred to in the present description includes the lower limit x
and the upper limit y. Any numerical value included in various
numerical values or numerical ranges described in the present
description may be selected or extracted as a new lower or upper
limit, and any numerical range such as "a to b" can thereby be
newly provided using such a new lower or upper limit.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 is a schematic view illustrating a state in which
water molecules are bonded to and incorporated in a molecule of
polyethylenimine which is one of polyamines.
[0022] FIG. 2A is a set of explanatory views schematically
illustrating a mechanism for sensing odors.
[0023] FIG. 2B is a set of explanatory views schematically
illustrating a mechanism for releasing odor components.
[0024] FIG. 3 is a schematic diagram illustrating the overview of
an apparatus used in an evaluation test for odors.
[0025] FIG. 4 is a graph obtained in the evaluation test according
to a first example.
[0026] FIG. 5 is a graph obtained in the evaluation test according
to a second example.
[0027] FIG. 6 is a graph illustrating the thicknesses of hydrated
layers on the surfaces of materials under test used in the
evaluation test.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0028] One or more features freely selected from the present
description can be added to the above-described features of the
present invention. In some cases, methodological features can even
be features regarding a product. Which embodiment is the best or
not is different depending on the objectives, required performance,
and other factors.
Polyamine
(1) Structure
[0029] Polyamine is a polymer having amino groups. Examples of the
polyamine include a linear aliphatic hydrocarbon having three or
more primary amino groups bonded thereto. A further specific
example is polyethylenimine (PEI).
[0030] The molecular formula of PEI is
(--CH.sub.2--CH.sub.2--NH--).sub.n, which has a molecular structure
as illustrated in FIG. 1. The main functional group is an amino
group (--NH--), which is a polar group. The distance between
adjacent amino groups (distance between adjacent N molecules) is
about 3.7 .ANG.. The molecular diameter of water that is
hydrogen-bonded to the amino group is about 2 .ANG.. From this
viewpoint, the distance between adjacent amino groups of the
polyamine is preferably 2 to 4 .ANG. and more preferably 2.5 to 3.5
.ANG. in an embodiment.
(2) Water Characteristics
[0031] The polyamine exists as if it grows on the base material
surface of the heat exchanger, and incorporates one to several
molecules of water so as to retain them. The water included in the
polyamine is strongly electrically bonded to the polyamine and is
not easily separated (evaporated, desorbed, etc.) from the
polyamine even when heated to a high temperature, unless heated to
a boiling point or higher. On the other hand, on the surface side,
condensed water (dew condensation water) or the like that can move
freely is easily generated and evaporated in accordance with
changes in the environment (temperature and humidity of the
atmosphere) to which the surface of the heat exchanger is
exposed.
[0032] In the present description, as appropriate, water that is
incorporated in the polyamine and is not easily released will be
referred to as "bound water," water that is easily generated on the
polyamine or easily evaporated from the polyamine will be referred
to as "free water," and water that exists in the transition zone
between the bond water and the free water and exhibits intermediate
characteristics between the two will be referred to as
"intermediate water." In the case of a heat exchanger (in
particular, an evaporator), a typical example of the free water is
the "condensed water" (dew condensation water) caused by dew
condensation of water vapor in the air, and the intermediate water
can be rephrased as "adsorbed water." In the present description,
as appropriate, the term "condensed water" will be used
synonymously with the "free water" and the term "adsorbed water"
will be used synonymously with the "intermediate water."
[0033] The bound water/intermediate water (also referred to as a
hydrated layer) formed on the polyamine has a thickness of
preferably 20 to 90 nm and more preferably 30 to 70 nm in an
embodiment. An unduly small thickness may deteriorate the
slow-release effect, while the bound water/intermediate water
having an unduly large thickness may be difficult to form. The
thickness of such a hydrated layer bonded on the polyamine can be
specified with a scanning probe microscope (SPM).
(3) Odor Characteristics
[0034] The odor components can be released, as illustrated in FIG.
2A, on the surface of the base material (e.g., an Al alloy fin) of
the heat exchanger. First, when no polyamine exists on the base
material surface, as illustrated in FIG. 2A (1), the odor
components are in a state of being dissolved, absorbed, and
condensed in the free water (e.g., condensed water such as dew
condensation water) generated on the base material surface. When
the free water evaporates due to a humidity decrease or a
temperature increase in the atmosphere to which the base material
surface is exposed, the odor components are also released at once
into the atmosphere as the free water evaporates. This rapidly
increases the concentration of odor components in the atmosphere,
so that people present in the atmosphere will strongly sense the
odors.
[0035] Next, when polyamine exists on the base material surface of
the heat exchanger, as illustrated in FIG. 2A (2), the odor
components are in a state of being dissolved, absorbed, and
incorporated in the free water (e.g., condensed water such as dew
condensation water) generated on the base material surface. This is
the same as the case in which no polyamine exists.
[0036] However, many of the odor components in the state of being
absorbed and further condensed are organic substances, and they are
often high molecules having polarity in themselves, many of which
are in a state of captured by the polar groups of the polyamine due
to electrical attraction. As a result, even when the free water
existing on the polyamine evaporates, the odor components are not
released at once as the free water evaporates. This is one of
differences from the case in which no polyamine exists as
illustrated in FIG. 2A (1).
[0037] Moreover, the intermediate water/bound water remaining in
the vicinity of the polyamine after the evaporation of the free
water is less likely to evaporate than the free water, and the
bound water hardly evaporates. Thus, the odor components, which
have moved to the hydrated layer composed of the intermediate
water/bound water as the free water evaporates, are also not
released into the atmosphere at once. This is another one of
differences from the case in which no polyamine exists as
illustrated in FIG. 2A (1).
[0038] Furthermore, when polyamine exists, water in the hydrated
layer evaporates moderately and the odor components continue to be
also moderately released as the water evaporates. When polyamine
exists, therefore, the odor components are not excessively
concentrated in the hydrated layer.
[0039] After the free water and the water in the hydrated layer
evaporate, when free water is generated again, part of the
low-concentration odor components which are temporarily held in the
hydrated layer is moved (distributed) to the free water and the
odor components come to a further low-concentration state, so the
hydrated layer does not continue to accumulate odors.
[0040] It appears that such phenomena are repeated on the polyamine
existing on the base material surface of the heat exchanger and act
synergistically, so that the odor components are not released into
the atmosphere at once (i.e., slowly released), and odors that are
strongly sensed by people can be suppressed.
(4) Release Behavior of Odor Components on Evaporator
[0041] The mechanism in which the existence of polyamine on the
base material surface of the heat exchanger allows the odor
components to be slowly released (release behavior of the odor
components) will be specifically described in detail with reference
to FIG. 2B. FIG. 2B schematically illustrates the release behavior
of odor components when PEI, which is a typical example of
polyamine, exists on an evaporator, which is a typical example of
the heat exchanger.
[0042] As illustrated in FIG. 2B (1), when the air conditioner is
turned on to start the operation of a compressor, the compressed
refrigerant expands adiabatically in the evaporator to lower the
surface temperature of the evaporator. This cools the air in
contact with the surface of the evaporator, and the water vapor
contained in the air is condensed into dew on the surface to become
the free water (condensed water, dew condensation water). Then, the
odor components contained in the air in contact with the evaporator
are taken into the free water through dissolution and/or
absorption. Part of the odor components taken into the free water
also moves to the hydrated layer composed of the intermediate
water/bound water just beneath the free water (on the base material
surface side). Thus, the concentration of odor components in each
type of water comes to an equilibrium state within a range that
allows the odor components to be incorporated in the water of each
layer.
[0043] As illustrated in FIG. 2B (2), when the compressor of the
air conditioner stops its operation, the surface temperature of the
evaporator starts to rise, and the free water existing on the
surface is evaporated (released) accordingly. At this time, the
odor components dissolved/absorbed in the free water and odor
components in other possible forms are released into the interior
room together with the water vapor (water molecules) of the free
water. As described above, however, part of the odor components
taken into the free water has been transferred (distributed) to the
hydrated layer composed of the intermediate water/bound water. As
such, highly concentrated odor components are not released into the
air-conditioned interior room in conjunction with the evaporation
of free water. Furthermore, the hydrated layer composed of the
intermediate water/bound water receives the electrical attraction
force from the PEI side and is less likely to freely evaporate like
the free water. Thus, even when the free water evaporates, the odor
components having transferred to the hydrated layer are not
released into the interior room at once.
[0044] As illustrated in FIG. 2B (3), when the compressor is
restarted, free water is generated again on the surface of the
evaporator. Odor components contained in the air gradually decrease
due to washing or the like of the evaporator surface associated
with the outflow of the free water. As a result, when the
concentration of odor components taken into the free water also
decreases, the odor components which are temporarily held in the
hydrated layer move moderately to the free water in an opposite
manner, and the concentration of odor components comes to an
equilibrium state in whole.
[0045] As illustrated in FIG. 2B (4), when the free water
evaporates due to stopping the compressor again, the odor
components having transferred from the hydrated layer to the free
water are also released in conjunction with the evaporation of the
free water. As will be understood, the concentration of odor
components released at this time is relatively low.
[0046] As illustrated in FIG. 2B (5), when the free water
evaporates and the amount of the free water decreases, the water in
the hydrated layer also starts to gradually evaporate. In
conjunction with the evaporation, the odor components contained in
the hydrated layer are also released. Also in this case, the
concentration of odor components released due to the evaporation is
low because the amount of odor components contained in the hydrated
layer is not large.
[0047] After that, when a hydrated layer is newly generated and
odor components are taken in from the air in contact with the
evaporator via the free water or the like, part of the odor
components is transferred to and held again in the hydrated layer
composed of the intermediate water/bound water with a reduced
concentration of the odor components. Then, the cycle illustrated
in FIG. 2B (1), FIG. 2B (2), etc. described above is repeated
again.
[0048] In any case, the PEI existing on the base material surface
of the evaporator has a polarity capable of temporarily holding the
odor components and generates the hydrated layer, and the odor
components are thereby prevented from being released into the
air-conditioned interior room at once. As a result, the odor
components are slowly released into the air-conditioned interior
room, the concentration change in the odor components in the
air-conditioned interior room becomes moderate, and people in the
air-conditioned interior room do not sense strong odors.
(5) Molecular Weight
[0049] The reason that the polyamine exhibits the slow-release
action for odor components is due to its molecular structure. As
the molecular weight changes, the thickness or the like of the
hydrated layer changes and the slow-release effect for the odor
components can also change. For example, the larger the molecular
weight, the larger the thickness of the hydrated layer, and the
slow-release effect and therefore the deodorization effect tend to
be enhanced. In this context, the molecular weight of the polyamine
is preferably 300 to 70,000 and more preferably 400 to 35,000 in an
embodiment. Polyamines with an unduly low or high molecular weight
are not readily available. From another aspect, an unduly low
molecular weight may reduce the slow-release effect while an unduly
large molecular weight may increase the viscosity so that the
adhesion to the base material surface will be difficult.
[0050] The molecular weight as referred to in the present
description is a well-known Z-average molecular weight (Mz) and
calculated as Mz=.SIGMA.Mi3Ni/.SIGMA.Mi2Ni (Mi: each molecular
weight, Ni: number of molecules of molecular weight Mi).
(6) Adhesion
[0051] The polyamine may exist as a simple substance of polyamine,
for example, on the base material surface of the heat exchanger or
may also coexist with one or more types of polymers, surfactants,
etc., other than the polyamine. Examples of polymers mixed with the
polyamine include those having one or more types of polar
functional groups such as an amino group, a carbonyl group, a
carboxyl group, an imide group, a hydroxyl group, a nitrile group,
a nitro group, a sulfide group, a sulfoxide group, a sulfone group,
a thiol group, and an ester group.
[0052] The adhesion form of the polyamine to the base material
surface is not limited. The polyamine may adhere only to the
surface layer of a polymer film or adhere to the entire film
including the inside of a polymer film or may also be a polymer
film composed of a composite component. The region (site) to which
the polyamine adheres may be a part or all of the heat exchanger.
The heat exchanger is provided with a large number of fine air
passages, so a coating method, a dipping method, or the like is
appropriately selected as the adhesion (film formation) method for
the polyamine in accordance with the shape of the heat
exchanger.
Heat Exchanger
[0053] The heat exchanger includes a flow path through which a heat
medium flows and air fins disposed around the flow path. The heat
exchanger is typically an evaporator, but may be a condenser, a
radiator, or the like as long as deodorization/odor suppression is
required, and may not necessarily be used for air conditioning.
Furthermore, the heat exchanger and equipment provided with the
heat exchanger may be used in any of moving vehicles (such as
automobiles, railway vehicles, aircrafts, and ships), homes,
business places, and the like.
EXAMPLES
[0054] On the assumption that people in an interior room would be
less likely to sense odors caused from a car air-conditioner (in
particular, from the evaporator), various samples to which odor
components were made adhere were prepared and a test was performed
to evaluate odors generated from each sample. The present invention
will be described in more detail with reference to such specific
examples.
First Example
Sample
(1) Base Material
[0055] A silicate-based glass plate (simply referred to as a "glass
plate"/Sample 11) was prepared as the base material (test piece) to
which odor components were to adhere. The size of the base material
was 16.times.76.times.1 mm.
(2) High-Molecular Film
[0056] The surface of the glass plate was coated with a
high-molecular film composed of PEI (simply referred to as a "PEI
film"). PEI is a typical example of polyamine. The film formation
was performed through introducing glycidyltrimethoxysilane into
silanol groups on the glass plate surface and making the PEI adhere
to the glass plate surface.
(3) Odor Components
[0057] Acetic acid, butyric acid, and trimethylamine (TMA) were
used as the odor components made to adhere to the base material.
These are all typical odor substances composed of organic
substances. The base material was immersed in a mixed aqueous
solution of these odor components (acetic acid: 1,000 ppm, butyric
acid: 100 ppm, TMA: 1,000 ppm) for 3 days. The base material pulled
out of the mixed aqueous solution was sufficiently washed with pure
water and then naturally dried indoors. The sample thus obtained
was subjected to odor evaluation.
Test
[0058] The release behavior of the odor components according to the
sample was checked using a test apparatus as illustrated in FIG. 3.
Specifically, first, the sample to which the odor components
adhered was put into a glass chamber, and N.sub.2 with conditioned
humidity using a mass flow meter and a humidifier was introduced
into the chamber. This chamber was alternately immersed in a
constant-temperature bath of high-temperature (30.degree. C.) and a
constant-temperature bath of low temperature (2.degree. C.) to
change the environment in the chamber (temperature and humidity in
the vicinity of the surface of the material under test). At that
time, the holding time at the high temperature was set to 15
minutes and the holding time at the low temperature was also set to
15 minutes.
[0059] For the air having passed through the chamber and led to a
discharge port, measurement of humidity change and sensory
evaluation (odor intensity evaluation) were performed. Along with
the sensory evaluation, the air was collected in a collection tube,
and the concentration analysis for each odor component was also
performed using a gas chromatography-mass spectrometer (GC/MS). The
results thus obtained are illustrated together in FIG. 4.
[0060] The upper part of FIG. 4 illustrates the humidity of the air
introduced into the chamber (WET/DRY), the holding temperature of
the chamber, and the humidity of the air led out from the discharge
port (sensory evaluation port). The middle and lower parts of FIG.
4 illustrate the sensory evaluation results and the GC/MS
measurement results obtained, respectively, for Sample 11 (with a
PEI film) and Sample C0 (an aluminum alloy sheet with no PEI
film/details will be described later).
Evaluation
[0061] As apparent from FIG. 4, it has been revealed that the
release behavior of odor components differs depending on the
presence or absence of the PEI film. Specifically, Sample 11 with
the PEI film showed a moderate change in both the odor component
concentration in the GC/MS and the sensory evaluation as compared
with Sample C0 with no PEI film. That is, it has been revealed that
the odor components are slowly released by virtue of the PEI film
and the odors are thereby less likely to be sensed.
Second Example
Samples
[0062] An aluminum alloy sheet (simply referred to as an "Al alloy
sheet"/Sample C0) was prepared as the base material to which odor
components were to adhere. This Al alloy sheet may be used for a
heat exchanger (evaporator) and is obtained by surface-treating an
aluminum alloy (A1050) with a hydrophilic resin. The size of the
base material was 16.times.76.times.0.2 mm.
[0063] In addition to the Al alloy sheet (Sample C0), Sample 21 and
Sample 22 were also prepared by coating the surfaces of respective
Al alloy sheets with high-molecular films (PEI films) having
different molecular weights (PEI molecular weight for Sample 21:
600, PEI molecular weight for Sample 22: 10,000).
[0064] The odor components were made to adhere to the sample in the
same manner as in First Example. The sample thus obtained was
subjected to odor evaluation.
Test
[0065] (1) The same sensory evaluation (odor intensity evaluation)
as in the case of First Example was performed for each material
under test. The obtained results are illustrated together in FIG.
5. The upper part of FIG. 5 illustrates the temperature of the
chamber and the humidity of the discharge port (sensory evaluation
port). The lower part of FIG. 5 illustrates the sensory evaluation
result according to each sample.
[0066] (2) The thickness of a hydrated layer existing on the
surface of the material under test of each sample (before the
sensory evaluation test) was measured using an atomic force
microscope (AFM: SPM-8000FM available from Shimadzu Corporation),
which is a kind of scanning probe microscope (SPM). The results
thus obtained are illustrated in FIG. 6.
Evaluation
[0067] (1) As apparent from FIG. 5, Sample C0 with no PEI film
showed a sharply peaked odor intensity. On the other hand, in
Samples 21 and Sample 22 with the PEI films, the odor intensity was
significantly reduced and the change in the odor intensity was
moderate. This tendency was more prominent in the sample with a
larger amount of amino groups introduced.
[0068] (2) From FIG. 6, it has been found that the thicknesses of
hydrated layers generated on the surfaces of the materials under
test were 9 nm in Sample C0, 30 nm in Sample 21, and 50 nm in
Sample 22. It has thus been revealed that as the molecular weight
of PEI increases, the thickness of the hydrated layer formed on the
surface of the material under test also increases, so that the odor
intensity is reduced and the change in the odor intensity is
suppressed.
[0069] (3) Furthermore, from FIG. 5, it has also been revealed that
the timing at which the odor intensity reaches the maximum (peak)
is different in each sample. Specifically, in Sample C0 with no PEI
film, the odor intensity was maximized in the vicinity of a time
point at which the humidity of the discharge port was maximized. On
the other hand, in Samples 21 and 22 with the PEI films, the time
when the odor intensity was maximized was delayed from the time
when the humidity of the discharge port was maximized. As
previously described, the maximum values of Samples 21 and 22 were
significantly reduced as compared with Sample C0.
[0070] (4) The reason that such a tendency was obtained is
considered as follows. In Sample C0 with no PEI film, it appears
that the release of odor components is in conjunction with the
evaporation of water from the surface of the material under test.
On the other hand, in Samples 21 and 22 with the PEI films, it
appears that the release of odor components is not necessarily in
conjunction with the evaporation of water and the odor components
continue to be moderately released (i.e., slowly released) by
virtue of the PEI films.
[0071] Moreover, as the sample is formed with PEI having a higher
molecular weight, the maximum value of the odor intensity is
reduced and the timing at which the odor intensity is maximized is
delayed. One reason for this appears to be because the higher the
molecular weight of PEI, the thicker the hydrated layer can be
formed on the base material surface, and a larger amount of odor
components can be temporarily held.
[0072] In any case, it has been revealed that the existence of the
polyamine on the base material surface of the heat exchanger allows
the odor components to be moderately released (slowly released),
and even when the ambient environment (such as humidity and
temperature) changes, the odor components are not rapidly released,
so that the odors which are strongly sensed by people can be
suppressed.
* * * * *