Note: Descriptions are shown in the official language in which they were submitted.
9,2~5~2~
This invention relates to a pre-testing method for
a weathering test on samples of plastic, fibre, coating
material, or the like. This application is a divisional
of Canadian Application No. 468,814 filed November 28,
1984.
Conventionally, in ~ea~u~em~n~. O;e w~atherabllit~
of plastic material or the like, weathering machines
according to JIS B7751 to 77$4 are generally used.
In these testing machines, ordinarily, a light
source such as a carbon arc lamp, xenon arc lamp or the
like is used and the light emitted from this light source
is irradiated onto a sample, thereby performing the
accelerated weathering test.
However, in these weathering machines, the
apparatus containing such a light source emits radiation
at an ultraviolet irradiation intensity of about 6 mW per
cm2 of the surface to be irradiated. Therefore, it takes
approximately hundreds of hours or longer to measure and
discriminate the ultraviolet deterioration characteristic
that equivalent1y corresponds to one year o irradiation
of solar light.
~2~
-- 2 --
Also, in the known methods all the samples in each
lot are subjected to testing so that there are problems in
that measurement and discrimination of the result is time
consuming and these methods are extrernely inefficient.
It is an object of the present invention to
provide a pre-testing method for allowing the weathering
test to be very eficiently performed.
According to this invention, there is provided a
weathering test comprising the steps of: irradiating a
plurality of samples with radiation that is generated by a
metal halide lamp containing mainly halide of iron
enclosed together with mercury and rare gas and that is
iltered by a filter that substantially removes wavelength
components other than ultraviolet wavelengths, the
filtered radiation havln~ an energy level sufeicLent to
deteriorate said samples in a short time; maintaining the
samples at a temperature that is low enough to prevent
substantial heat deterioration of the samples during the
irradiating; and selecting from the plurality of samples a
sample which should be subjected to the weathering test in
accordance with the degree of the deterioration.
Use oE the pre-testing method allows the tendency
and degree of ultraviolet deterioration characteristic of
the sample to be determined with high accuracy in an
extremely short time. Therefore, on the basis of these
results, only the samples which should be tested by the
weathering machine ~ay be selected and tested. Thus,
there is an advantage in that the entire test may be
~ efficiently executed. Also, the testing apparatus for use
; 30 in the pre-test method has a simpler structure than the
weathering machine and is economical.
~5~9:~
-- 3 --
Fig. 1 shows a spectral energy distribution
diagram of a metal halide lamp for an ultraviolet light
source which is used in this invention;
Fig. ? shows a transmission characteristic diagram
of a filter which is used in combination with the metal
halide lamp;
Figs. 3A and 3B illustrate a front view and a side
elevational view of the light source in combination with
the metal halide lamp and filter, respectlvely;
Figs. 4A and 4B illustrate a front view and a side
elevational view of a pre-testing apparatus for use in the
present invention, respectlve~y; and
Figs, 5 to 10 show comparlson diagrams between the
test result in examples oE the invention and the test
result by a conventional method.
; An embodiment of the present invention will now be
described by way of example only. First, necessary
samples are produced for every lot.
Next, ultraviolet rays having an intensity of 50
mW or more per cm2 of the surface to be irradiated ~re
irradiated onto these samples by a light source in
combination with a high pressure metal vapor electric
discharge lamp and a filter which transmits only the
ultraviolet rays within a wavelength range of 300 to 400
nm under the condition whereby the temperature of the
sample is 80C or less. The reason for the wavelength
range of the ultraviolet rays specified above is that the
test conditions specified by a JIS rule are not satisfied
if the wavelength range is less than 300 nm, and strictly
~25~ 4
speaking, less than 275 nm. Also, in the case where the
wavelength range is over 400 nm, many visible and infrared
rays are included in the light that is irradiated from the
light source, so that the sample is largely thermally
affected. Therefore, it is necessary to avoid such
influences, and the like.
From an economical viewpoint a desirable range for
irradiation intensity of the ultraviolet rays on a sample
is approximately 80 to 200 mW per cm~ of the surface to be
irradiated although a higher irradiation intensity may be
preferable. More preferably, a range of about 100 to 150
mW is used. The optimum high pressure metal vapor
discharge lamp to obtain such a wavelength range and
intensity is set forth in, Eor example, the oEficial
gazette o ~apanese Patent ~pplication P-~bliqati~n ~aid-
open No. 187~3/19B3. This lamp is a metal halide l~mp irl
which a halide oE a metal such as iron and tin is enclosed
together with proper quantities of mercury and rare gas in
a light emitting tube made of quartz glass and having at
least a pair of electrodes. The light emission spectrum
of this metal halide lamp has a fairly large energy
distribution in the wavelength range of 300 to 400 nm as
shown in Fig. 1. This metal halide lamp is not limited to
the lamp wherein the halide of iron and tin has been added
into the light emitting tube but also may be a lamp
wherein metal halide, mainly containing halide of iron,
has been enclosed in the light emitting tube.
A carbon arc lamp having an energy peak in the
wavelength range of 300 to ~00 nm has been used in
weathering machines to date. However, this lamp
irradiates many infrared rays as well as ultraviolet
rays. Also gases such as CO, CO2, NO, NO2, etc. are
generated while the lamp is lighting. ThereEore~ as dis-
closed in the official gazette of Japanese Utility Model
9~
-- 5 --
Application Publication Laid-open No. 16796/1~77, the lamp
itself has to be equipped with cooling and ventilating
mechanisms, causing the lamp and overall apparatus to
become complicated and to be increase~ in size and cost.
Thus, this type of lamp is not suited for implementation
in the present invention.
Even in the metal halide lamps described abo~e, it
is impossible to avoid irradiation of energy in a wave-
length range other than 300 to 400 nm. Therefore, it is
necessary to restrict the irradiated wavelength range of
the lamps to 300 - 400 nm by use in combination with a
proper filter. The optimum filter used for this purpose
is a filter made of soft glass having a low meltiny point
and which consists of, Eor example, 60 - ~5% SiO2, 15 -
20~ Pb, 7 - 8~ Na, 7 - ~ K, l~ Co, and 1~ Ni, where all
percen~ages are hy masY.
The ultraviolet transmission characteristic of
this filter is as shown in Fig. 2. By combining this
filter with the metal halide lamp, ultraviolet rays of
wavelengths 290 to 460 nm, and particularly 300 to 400 nm,
are obtained extremely efficiently. However, if this
filter is merely attached around the metal halide lamp,
radiation heat froM the lamp will immediately damaye the
filter. Therefore, for example, as shown in ~igs. 3A and
3B, a water cooled light source 6 is suitably constituted
in a manner such that: a water cooled jacket 2 has an
inner tube 2a and an outer tube 2b which consist of quartz
glass which can transmit the ultraviolet rays; a cooling
liquid is circulated between the inner and outer tubes 2a
and 2b; a light emitting tube 1 is arranged at the centre
of the inner tube 2a of the wafer cooled jacket 2; and a
filter 3 is disposed between the inner and outer tubes 2a
an~ 2b.
~L~5~
-- 6 --
In the official gazettes of Japanese Utility Model
Application Publication Laid-open Nos. 29675/1977 and
29034/1979, apparatus are disclosed in which, in the
weathering machine, the ultraviolet rays in a particular
wavelength range of, say, 300 - 400 nm are controlled by
combining a filter with a lamp. However, in both such
apparatus, the radiation energy of thle lamp varies depend-
ing upon the time lapsed since lighting of the lamp and
upon changes in power source voltage, so that the energy
components in a particular wavelength range also change.
m erefore, to ensure constant energy components, any
energy change in the particular wavelength range is
detected to control a voltage which is applied to the lamp
in accordance with the change. Consequently, the above-
ment~oned apparatus are ~uite dif~erent from the apparatuso~ thi~ invention in which the light emitted erom the lamp
is irradiated onto the sample through the filter.
Figs. 4A and 4B illustrate a front view and a side
elevational view of an example of a testing apparatus to
implement the present invention. In the drawings, a
reference numeral 4 denotes a testing apparatus main body;
4a is an ultraviolet irradiating chamber; and 4b is a
chamber for enclosing attached apparatus. A light source
apparatus 6' is provided over the ultraviolet irradiating
chamber 4a. The light source apparatus 6' ~omprises a
reflecting mirror 5 and the light source 6 such as a metal
halide lamp or the like attached in the apparatus 6'. A
sample mounting plate 7 is disposed below the light source
6 so as to be vertically adjustable and rotatable as
necessary. The distance between the sample mounting plate
7 and the light source 6 can be adjusted by vertically
moving either of or both of the sample mounting plate 7
and the light source apparatus 6'.
9~2~
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The reason for constituting the testing apparatus
in this way is to eliminate a variation in distance
between the sample and the light source 6 due to the
capacity of the light source 6, thickness of sample, etc.
5 By suitably selecting the capacity of the light source 6
and the distance between the light source 6 and the
sample, it is possible to irradiate onto the sample
ultraviolet rays having an intensity of 50 mW or more per
cm2, preferably, 80 to 200 mW, and more desirably, 100 to
150 mW. Also, in order to uniformly irradiate the
ultraviolet rays onto the sample, the sample mounting
plate 6 can be freely rotated as necessary.
An air blower 8 is used to cool the sample mount-
ing plate 7 and the air in the ultraviolet irradiating
lS chamber ~a is exhausted to the outside by an air exhaust-
in~ apparatu~ n the case where the sample is
irradiated with strony ul~raviolet rays, it i~ necessary
to maintain the sample at temperatures below about 80C to
prevent deformation of the sample due to the heat.
However, as mentioned above, this temperature can be
easily controlled by using the means in which the water
cooled metal halide lamp is used as the light source in
combination with the filter and also by using the means in
which the sample is cooled by use of the air blowing and
~5 exhausting apparatus, and the like~ Table 1 shows the
ultraviolet irradiation time and the temperature of the
sample when the surface of the sample is irradiated by the
ultraviolet rays of a constant intensity in the cases
where: only the water cooled metal halide lamp is used
3~ (no filter); the filter is combined with this lamp (filter
is used); and the means for cooling the sample is also
used in addition to the filter (filter and sample cooling
means are used), respectively.
Table 1
_ __ .
Ultraviolet Filter and
rays irradi- sample cool-
ation intensity No filter Filte:r ing means
(mW/cm2) is used are used
For one For ten
20 - 60 hour and hours and
at 100C at 100C For 100
or over or over hours or
_ more and
For 0.3 For one at 65C
80 - 120 second and hour and or below
at 100C at 100C
or over or over
_ ___. . _ ___
AS will be clear from this table, in the case
where the filter is combined with the water cooled metal
halide lamp and the sample cooling means is also utilized,
even if the strong ultraviolet rays having an intensity of
80 to 120 mW/cm2 are irradiated onto the sample for more
than a hundred hours, the sample can be maintained at
temperatures of 65C or below.
Alternatively, the cooling of the sample may be
controlled by control of the input to the lamp or the
temperature of the sample mounting plate in addition to
the control of the quantity and temperature of the cooling
air. Further, a pump, cooler and the like for the cooling
water to the light source are enclosed in the chamber 4b
for enclosing the attached apparatus in addition to a
power supplying apparatus, ballast apparatus and the li]ce
for the light source.
- 9 - ~
In such a testing apparatus as described above,
for example, in the case where a metal halide lamp of a
rated input of 1.5 kW is used as the metal halide lamp of
the light source and the distance between the light source
- 5 6 and the sample mounting plate 7 is set to 10 cm and the
light source 6 is used at the rated input, the ultraviolet
irradiation intensity on the sample mounting plate 7 is
about 100 mW per cm2. This value is approximately 10 to
15 times larger than the ultraviolet irradiation intensity
of a conventional weathering machine. When it is assumed
that the ultraviolet deterioration characteristic of the
sample, when such strong ultraviolet rays are irracliated
onto the sample, has a similar tendency to the ultraviolet
deterioration characteristic of the sample which is tested
by the actual weathering machine, it is possible to
disc~iminate the ultraviolet deterioration characteristic
eor the timQ interval. This tLme interval is about 1/10 -
1/15 shorter than the time interval that is needed in the
case where the weathering machine is used.
As described above, the use of the foregoing
method enables the ultraviolet deterioration characteris-
tics of the samples for every lot to be discriminated in
an extremely short time. Therefore/ if the samples are
selected from among these samples in accordance with a
degree of ultraviolet deterioration and are tested by the
weathering machine, the superfluous tests and time can be
omitted, so that the test becomes very ef~icient.
The largest problem in use of the testing method
is whether or not the ultraviolet deterioration character-
istic of the sample irradiated by strong ultraviolet rayshave the same tendency as the ultraviolet deterioration
characteristic of the sample which was tested by the
weathering machine. Unless they have the same tendency,
the pre-testing method according to the invention will be
:;
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meaningless. Therefore, as shown in the following exam-
ples, many samples consisting of various kinds of plastic
materials were tested by the testing apparatus (herein-
after, referred to as the pre-testing apparatus) to imple-
ment the invention and by the weathering machine (herein-
a~ter, referred to as the formal testing machine~, and the
tendency and degree of the ultravi~let deterioration were
examined. The testing apparatus and machine used in each
example and the test conclitions are as follows.
(1) Pre-testing apparatus
Model ... The apparatus made by Iwasaki Electric Co.,
Ltd. (with a structure as shown in Figs. 4A and
4B)
Con~itions
r~,arnp u~ed: Metal halide lamp of 1.5 kW
~adiatLon wavelen~Jth: 300 - 400 nm
Energy distribution: As shown in Fig. 1
Ultraviolet irradiation intensity on the
surface of the sample: 100 + 5 mW/cm2
The highest temperature at the sample
surface: 65C or less
(2) Formal testing machine
Model ... WE-SUN-HC* made by Toyo Electrochemical Industry
Co., Ltd. (testing machine which is used in the
testing method based on JIS A1415)
Conditions
Lamp used: Carbon arc lamp of 4 kVA
Ultra~iolet irradiation intensity on
the surface of the sample: 6 mW/cm2
Black panel temperature: 63 + 3 C
Spray: 18 min/120 min
* Trade mark
-
~2S~24
- 11 -
Also, in this test, the tendency and degree of the
ultraviolet deterioration were examined from the changes
in color difference and physical property of the sample
which had been tested by the above testing apparatus and
machine. A discriminating method and the test result in
the practical example with regard to each of the color
difference test and physical property test will now be
explained hereinbelow, respectively.
In the following examples, typical plastic
materials were selected as samples and they were tested
under the particular conditions as mentioned above. The
invention is not limited to these examples.
(( ~ )) Color di~eerence test
With respe~ct to the samples at every ti.me ob~lne~
by the above two testing apparatus and machine, the whole
color differences before and after the test were obtained
and they were plotted in the graph in which an axis of
abscissa indicates the time and an axis of ordinate
represents the color difference. Each time the same color
difference was read and the ratios of the times regarding
the formal testing machine and pre-testing apparatus were
obtained. Then, the magnifications of the ultraviolet
deterioration accelerating properties were derived. For
the whole color difference,~ E (color difference) was
obtained from CIEL* a* b* which is the colorimetric system
on the basis of the International Illumination Commi~tee
in 1976. As the color difference meter, CR-100* (Trade
mark) made by Minolta Camera Co., Ltd. was used.
~L2~;5~
(Example 1)
Sample: Hard transparent PVC sheet containing organic
tin. The thickness is 0.4 mm.
The stimulus values of the XYZ system which is
the colorimetric system on the basis of the
International Commission on Illumination in 1931
are X, Y and Z, while the chromaticity
coordinates are x and y, namely:
x = X
X + Y + Z
y = Y
X + ~ + ~
In this example, the reference color is set
such that Y ~ 47.4, x ~ 0.307 and y ~ 0~311,
wherein, behlnd the sample, a white sheek l~
placed.
Result: In case of the formal testing machine
As shown in Fig. 5A.
In case o~ the pre-testing apparatus
As shown in Fig. 5B.
Comparison: As shown in Table 2 (mean magnification:
12~7)-
Table 2
_
~E Formal testing machine Pre-testin~ apparatus R/P
R(hours) P(hours)
_ _ .
42 o 450 35 132 97
308.0 920 76 12.1
10.0 1000 84 11.9
___
(Mean: 12.7)
-
- 13 -
As will be clear from the above experimental exam
ple, the use of the pre-testing apparatus enables the data
regarding the ultraviolet deterioration of the sample to
be obtained in a short time compared to the case where the
formal testing machine was used. The difference between
the test times was approximately a multiple of thirteen.
This result nearly coincides with the prediction value
calculated from the difference in ultraviolet irradiation
intensity per cm2 of the surface to be irradiated. Thus,
it was confirmed that the ultraviolet deterioration
characteristic of the sample in the case where the pre-
testing apparatus was used has substantially the same
tendency as that in the case where the sample was tested
by the formal testing machine. In addition, the sample
was maintained at a temperature below about 65C during
the test and even in case of the hard vinyl chloride or
the like, deformatlon or the like due to the heat was not
caused at all.
tExample 2)
20 Sample: ABS sheet (Grade: A-322 made by Toray
Industries, Inc., Natural). The thickness is
2.0 mm.
(Reference color: Y = 62.5, x = 0.328,
y = 0.342)
25 Result: In case of the formal testing machine
As shown in Fig. 6A.
In case of the pre-testing apparatus
As shown in Fig. 6B.
Comparison: As shown in Table 3 (mean magnification:
15-4)-
.
~ 9
- 14 -
Table 3
AE Formal testing machine Pre-testing apparatus R~P
R(hours) P(hours)
_ . .
2.0 30 2 15.0
4.0 70 5 14~0
8.0 160 11 14,5
10.0 270 15 ~ a . o
(Mean: 15.4)
(Example 3)
Sample: Acryl ic denaturat:ion PVC sheet (Trade mark:
Dalpla AV sheet). The thlckne~s i.s 3.0 mm.
(Reeerence color: Y = 73.7, x ~ 0~320,
y ~ 0,31~)
Result: In case of the formal testing machine
As shown in Fig. 7A.
In case of the pre-testing apparatus
As shown in Fig. 7B.
; Comparison: As shown in Table 4 (mean magnification:
14.3)-
Table 4
_ _ _
~E Formal testing machine Pre-testing apparatus R/P
R(hours) P(hours)
. . _ . _
4.0 250 25 10.0
8.0 480 3~ 12.6
12.0 740 47 15.7
¦ 16.0¦ 1000 53 18.9
_ ._ _
(Mean: 14.3)
- 15 -
(Example 4)
Sample: Polycarbonate ~Trade mark: Daipla Double
Skin sheet PD-600). The thickness is 6.0 mm.
(Reference color: Y = 34.9, x = 0.314,
y = 0.317)
Result: In case of the formal testing machine
As shown in Fig. 8A.
In case of the pre-testing apparatus
A5 shown in Fig. 8B.0 Comparison: As shown in Table 5 (mean magnification:
13.8).
Table 5
_ _ ___~__ _
aE Formal testing machlne Pre-testin~ ~pparatus ~/P
R~hour~) P(hours)
_. ___ _
2.0 160 12 13.3
~.0 320 27 11.9
6.0 500 43 11.6
8.0 1150 63 18.3
(Mean: 13.8)
(Example 5)
Sample: Polyethylene sheet ~Grade: Hizecks* 5000SF
made by Mitsui Petrochemical Industries,
Ltd.).
The thickness is 0.5 mm.
(Reference color: Y = 57.2, x = 0.305,
y = 0.309)
* Trade mark
,
- 16 -
Result: In case of the forma] testing machine
As shown in Fig. 9A~
In case of the pre-testing apparatus
As shown in Fig. 9Bo Comparison: As shown in Table 6 (mean magnification:
10.3)-
Table 6
__
~E Formal testing machine Pre-testing apparatus R/P
R(hours) P~hours)
0.5 220 22 10.0
1.0 500 48 10.4
1.5 920 88 10.5
(Mean: 10.3)
As will be clear from the comparison data in
Examples 1 to 5, use of the pre-testing method enables
data regarding the ultraviolet deterioration of the sample
to be obtained in a short time as compared to the case
where the formal testing machine was used. The difference
between the test times was about 10 to 20 times and the
mean value was about 15 times. This result almost
coincides with the prediction values calculated from the
difference in ultraviolet irradiation intensity per cm2 of
the surface to be irradiated. Thus, it was confirmed that
the ultraviolet deterioration characteristic of the sample
in the case where the pre-testSng method was used has
substantially the same tendency as that in the case where
the sample was tested by the formal testing machine. The
reason for the difference in acceleration of the
ultraviolet deterioration in the various kinds of plastic
materials is that the absorption characteristics of the
~25~ 24
17 -
ultraviolet rays differ due to the molecular structures
and first hues of the plastic materials. On the other
hand, there is a tendency such that the magnification also
becomes large with an increase in ~E. It can be consi-
dered that this is because no water is used in the pre-
testing apparatus so that the degree of stain on the
surface of the sample is less than that in the case where
the formal testing machine was used and therefore the
ultraviolet deterioration was accelerated.
(( B )) Physical property test
B-1) Bending test at a bend angle of 180
After the ultraviolet rays had been irradiated
- onto the portion of 30 mm2 of the central portion of the
sample having a width of 10 mm and a length of 65 mm by
the formal testing machine and by the pre testing
appara tllS ~ the degree of physical property deterioration
Oe the sample was examined due ~o the repetitive Eol~lng
operations at a bend angle o 180.
(Example 6)
20 Samp~e: Polypropylene sheet (Grade: RB-110* made by
Tokuyama Soda Co., ~td.). The thickness is
0.2 mm.
(Reference color: Y = 65.5, x = 0.312,
y = 0.316)
Result and comparison: As shown in Table 7.
* Trade mark
~s~
- 18 -
..
Table 7
,
Formal testing machine Pre-testing apparatus
Irradiation Degree of Irradiation Degree of
time deterioration time deterioration
(hours) * (hours) *
_
100 A 10 A
200 A 20 A
300 B 30 B
500 40 _C
*A : The sample was not cut even when it had been folded
50 times or more.
B : The sample was cut when it had been Eolded 20 times
or more.
C : The ~ample wa~ cut when it had been olded once.
B-2) Tensile impact test
The test was performed on the basis of ASTMD1822
using the universal impact testing machine made by ToyO
Seiki Mfg. Co., ~td. The ratios of the times regarding
formal testing machine and pre-testing apparatus were
obtained in a similar manner as in case of the color
difference. Then, the acceleration properties (magnifica-
tions) of the ultraviolet deterioration were derived.
(Example 7)
30 Sample: Acrylic denaturation PVC sheet (Trade mark~
Daipla AV sheet). The thickness is 3.0 mm.
Result: In case of the formal testing machine
As shown in Fig. 1OA.
In case of the pre-testing apparatus
As shown in Fig. 1OB.
Comparison: As shown in Table 7 (mean magnification:
7.8)
~2~
- 19 -
- Table 8
Formal test-Pre-testing _
Impact value ing machinea]pparatus R/P
(kg-cm/cm2) R(hours) P~hours)
_
180 120 20 6.0
150 160 26 6.2
110 270 34 8.0
700 65 10.
(Mean: 7.8)
~s will be clear Erom the data in Examples 6 and
7, the u~e of the pre-te~ting method also enables the data
regarding the ultraviolet deterioration on the phy~ical
property sureace O;e the sample to be obtained in an
extremely short time as compared to the case where the
formal testing machine was used.
