Note: Descriptions are shown in the official language in which they were submitted.
:~04~174
This invention relates to improvements in and relating
to adhesive compositions and more particularly to a pressure-
sensiti~e adhesive composition comprising a blend of a rubber
component and an aromatic hydrocarbon resin.
Generally, pressure-sensitive adhecive compo~itions
are considered satisfactory if they have a proper balance of
tackiness, adhesive stren~th, cohesive stren~hh and weather-
resistance. Resinous materials which serve as the adhesion-
and tack-imparting component must be highly compatible with
rubbers and soluble in solvents.-
Heretofore, pressure-sensitive adhesive compositions
which are useful as adhesive coatings on tapes, sheets of
paper, fabric and other backing materials have been proposed
which are mixtures of natural rubber and/or synthetic rubber
with a terpene resin. This resin is alp~a-pinene, beta-pinene
or mixtures thereof which are-present in refined pine resins.
The~e naturally occuring substances are limited in their origin,
and their resources are growing more and more scarce with con-
siderable yield and price fluctuations.
As the-tac~$i~r~-f r E~essure-sensitive adh~sive com-
positions there are also known rosin esters, aliphatic hydro-
carbons and cumaDQne~-indenQ resin. These resins however are
inferior to terpene resins in the balance of cohesive stre~gth,
adhesive strength, tackiness and other important properties,
and are furthermore not-ver~-compatibl~ with rubbers or not
well soluble in solvents.
Therefore, it is the primary object of this invention
to provide improved pressure-sensitive adhesive compositions
~.~
- 2 - ~
~046~74 ~ ~which contain synthetic or natural rubbers in combination
with aromatic hydrocarbon resins which are less costly, more
abundantly available and comparable to or even better in
~uality than terpene resins.
In accordance with the invention, there is provided a
pressure-sensitive adhesive composition which comprises 100
parts by weight of a rubber component including styrene-
butadiene copolymers or rubbery mixtures chiefly consisting of
styrene-butadiene copolymers, in combination with from 20 to
140 parts by weight of a resin component consisting of an
aromatic hydrocarbon resin resulting from the polymerization
of a thermally cracked petroleum fraction at temperatures in
the range of -30 to +60~. in the presence of a ~riedel-Crafts
catalyst added in amounts ~f 0.01 to 5 weight percent of said
fraction, said fraction boiling in the range of 140 to 220C
and having a conjugated diolefin content of 0.7 weight percent
or less, a rate of conjugated idiolefin content of 3 percent
or less, a total content of indene and its alkyl derivatives
of 2 weight percent of less and a rate of indene content of
8 percent or less.
The term rubber component as used herein includes
$tyrene-butadiene copolymer rubbers commonly known as SBR and
rubbery mixtures chiefly consisting of SBR. Illustrative
of these rubber components are cold rubber type SBR or hot
rubber type SBR prepared by an emulsifying polymerization ~-
process, and random copolymer type or block rubber type SBR
prepared by a solution polymerization process. These SBRs may
be mixed ~ith other tvpes of rubber such as for example natural
rubber, isoprene rubber, butyl rubber, polyisobutylene,
~ 3
.~ . - . . . .
~046~'74
butadiene rubber, ethylen0-propylene rubber, ethylene-propylene
d:Lene rubber, chloroprene rubber, nitrile rubber and the like.
Preferred among these rubbers are natural rubber and isoprene
rubber. They may be used in amounts of 0 - 100 parts by
weight, preferably 0 - 80 parts by weight, more preferably
0 - 60 parts by weight per 100 parts by weight of SBR.
The term resin component includes aromatic hydrocarbon
resins resulting from the polymerization of a thermally
cracked petroleum fraction having a boiling point in the
range of 140 to 220C.
Generally, petroleum hydrocarbon resins are prepared
by polymerizing thermally cracked, normally liquid petroleum
oil fractions and have boiling points ranging between 20 and
280C, between 20 and 170C and between 140 and 280C. When
a petroleum fraction boiling in the range of 20 to 140C is
used for polymerization, the resulting resin will be non-
aromatic with no aromatic ring. Since such fraction contains
large amounts of conjugated diolefins and non-conjugated
diolefins, the resin has a high degree of unsaturation and
hence a very low weather-resistance. With petroleum fractions
boiling in the range of 140 to 280C, the resulting resin
will be aromatic but still not quite satisfactory in its
resistance to weather.
A close investigation of the characteristic properties
of each of the various components in the starting petroleum
fractions has now indicated that it is possible to obtain
a highly satisfactory tack-imparting resin by precise separa-
tion of certain selected components in the starting oil.
1046174
The resin component of the pressure-sensitive adhesive
composition according to the invention is an aromatic hydro-
carbon resin prepared from a starting petroleum fraction boiling
in the range of 140Q to 220C and containing unsaturated com-
pounds which are substantially styrene and its derivatives,
and indene and its derivatives. This starting material is
regulated to satisfy a condition such that the content of con-
jugated diolefins i8 0.7 weight percent of less, the rate of
conjugated diolefin content is 3 percent of less, the total
content of indene and its alkyl derivatives is 2 weight per-
cent or less and the rate of indene content is 8 percent or less.
The starting material is subjected to polymerization in the
presence of a Friedel-Crafts catalyst. The catalyst is removed, ;
and thereafter unreacted petroleum fraction and low molecular
polymers are removed by evaporation or distillation, whereby
an aromatic hydrocarbon resin having the desired properties is
obtained.
The starting material for the resin employed in accord- ~
ance with the invention is a thermally cracked petroleum fracr ~ -
tion boiling in the range of 140 to 220OC which is present in
the by-products obtained when ethylene, propylene, butenes and
butadienes are produced by thermal cracking as by for example
steam cracking of petroleum fractions such as naphtha, kero-
sene and light oii fractions.
A gas chromatographical analysis was made of the petro- ;
leum fraction boiling in the above range, with the results
tabulated below.
,,
- 5 - ~
;,.~. .. .. . . .
, ~: - , . .
: . ,
1046174
TABLE I-COMPONENTS IN CRACKED OIL OF 140 - 220C
FRACTION
Boiling
Component Point C Content
_ Hg abs) Percent)
Styrene ------------------------------ 145.8 13-20
Allylbenzene ------------------------- 156-157 0.1-1
~-Methylstyrene ----------~ ---- 165.4 0.5-6
~-Methylstyrene ---------------------- 175 0.5-6
p-Vinyltoluene ----------------------- 168~
m-Vinyltoluene ----------------------- 169~ 10-20
o-Vinyltoluene ----------------------- 171J
Indene ------------------------------- 182.2 2-11
Methylindene homologs ---------------- 184-206~
Dimethylindene and ethylindene~ 1-3
homologs ------------------------ 4~212J
Xylene (o-, m-, and p-isomers) ------- 138-142~
Ethylbenzene ------------------------- 136.2~ 17-10
Isopropylbenzene --------------------- 152.5J
Ethyltoluene (o-, m-, and p~-isomers) - 158-164.6 18-7
n-Propylbenzene ---------------------- 159.6 1-0.1
Trimethylbenzene (1,3,5-, 1,2,4-,
and 1,2,3,-isomers) ------------- 164.6-176.5 25-6
Indane ------------------------------- 177 9-1
Methylindane homologs ---------------- 182-203
Dimethyl and ethylindane
homologs -----------------~ 200~ 2-0.5
Naphthalene -------------------------- 218J
Dic~yclopentadiene (1) ---------------- 170 0.2-3
Undetected component (2) -------------140- 220 0.7-5.4
.
- ~0461'74
Note ~ A part or whole of the dicyclopentadiene may in
some cases be depolymerized with heat into cyclo-
pentadiene.
~2): A part of the undetected component contains cyclo-
pentadiene-methylcyclopentadiene co-dimer and
methylcyclopentadiene dimer. A part o~ whole there- - '
of may in some cases be depolymerized with heat
into cyclopentadiene and methylcyclopentadiene. It
is possible to analyze these monomers by gas chroma- ;
tography.
The total of styrene and its derivatives, indene and ~ ;~
its derivatives is considered as the polymerizable component.
In case cyclopentadiene and methylcyclopentadiene are produced -~-
by heating and contained in the starting oil as described in
Notes (1) and (2) of Table I, these monomers are also considered
as polymerizable components.
In order to produce a hydrocarbon resin suitable for
the purpose of the invention, it is essential that a thermally
cracked petroleum oil fraction boiling in the range of 140 to ~-
220C be precisely distilled to obtain a particular fraction ,
which satisfies the following conditions. The former fraction
is conveniently referred to as "starting cracked oil", and the
latter fraction as "starting fraction".
STARTING FRACTI ON ;
(a) The total content of cyclopentadiene and methyl~
cyclopentadiene, that is, the content of conjugated diolefin
in the starting fraction separated from the starting cracked
~V461'74
oil is adjusted to a value of 0.7 wt. percent or less and the '~
rate of content of the conjugated di~efin defined in the
following equation (1) is adjusted to 3% or less.
Rate of con~ugated diolein content (%)
Conjugated diolefin content in the
_ starting fraction (wt. ~) x 100 --- (1)
Polymerizable component in the
starting fraction twt. %)
(b) The total content of indene and its alkyl deriv-
atives in the starting fraction is adjusted to a value of 2 wt.
percent or less and the rate of content of the indene defined
in the following equation (2) is adjusted to 8% or less.
.
Rate of indene content (%)
Content of indene and its alkyl
derivatives in the starting fraction
(wt. %) ' ' x 100 --- (2)
=
Polymerizakle componea~ in the
starting fraction (wt ~)
Each component of the starting cracked oil and of the ~ ,
starting fraction is ana~yzed by gas chromatography under the
following conditions.
(1) Styrene, allybenzene, 1,3,5-trimethylbenzene, ,
and o-ethyltoluene are analyzed at 100C with a flow rate of
' ,helium at 60 cc/min. by empl ~ g a co~umn 3 meters long in
which UCelite''* (manufactured by Johns-Manville Corp.) con-
taining 20% by w~ight of "Apiezon L"** grease (manufactured('by
Associated Electri~al,Industries Ltd.) is filled.
*Trademark for a 325-mesh uncalcined, amorphous diatomaceous
earth.
**Trademark for a hydrocarbon grease having a very low vapor
pressure and good thermal stability produced by a molecular
distillation.
-- 8 --
~0461~4
(ii) Other components than those listed in (i) is
analyzed at 125C with helium flowing at a rate of 60 cc/min.
by employing a similar column in which "Celite" containing
20% by weight of polyethylene glycol 4,000 is filled.
The total content of styrene, its alkyl derivatives,
indene, its alkyl derivatives, cyclopentadiene, and methyl- ;
cyclopentadiene analyzed as above is considered as a poly-
merizable component.
For the separation of the starting fraction from the
starting cracked oil, there may be employed any convenient
and suitable process such as for example atmospheric dis- ;
tillation, vacuum distillation and extractive distillation.
Ac previously stated, it is one of the requisite
conditions in the preparation of the starting fraction from
the starting cracked oil that the total content of cyclo-
pentadiene and methylcyclopentadiene, namely, the content of
conjugated diolefin should be held at a value of 0.7 weight
percent or 12ss and the rate of conjugated diolefin content
at 3 percent or less. This condition may be conveniently ;~
met with by distilling either the starting cracked oil or
the fraction which contains the required total content of
indene and alkyl indene and the required rate of indene
content, thereby selectively removing conjugated diolefins.
This operation is facilitated by the fact that the boiling
points of cyclopentadiene and methyl cyclopentadiene are
42C and 70C, respectively, which are lower than the initial
boiling point of the starting cracked oil.
1046174
If these conjugated diolefins are in the form of
Diels-~lder dimers as found in the starting cracked oil,
there may be conveniently employed an atmospheric distilla-
tion to obtain the adjusted values of total indene content
and rate of indene content, in which distillation the con-
jugated diolefin dimers can be depolymerized into conjugated
diolefins which may be thereafter removed from the starting
fraction by distillation.
However, if such conjugated diolefin dimers are found
only in a minor proportion in the starting fraction, it is
not always necessary to remove them because the dimers as
compared to conjugated diolefins are less harmful to the
resulting resin with respect to its resistance to weather
and heat.
In order to satisfy the second requisite condition
that the total content of indene and alkyl indene is 2 weight
percent or less and the rate of indene content is 8 percent
or less, the starting cracked oil may be conveniently dis-
tilled to remove conjugated diolefins, with the distillate
further subjected to precise fractionation. Since o-
vinyltoluene and indene normally boil at 171C and 182~2C,
respectively, this boiling difference may be utilized so that
the starting fraction satisfying the requirements of the
resin of the invention can be taken overhead from the column.
In the art of petroleum resins it is an entirely new
concept to take a selected component in a thermally cracked
petroleum oil and subject it to a precise fractionation to
obtain a fraction having highly restricted characteristics.
-- 10 --
-
104t;174
Particularly, as disclosed herein, this concept is directed
to restricting the content and rate of content of c~jugated
diolefins and indenes;to certain values a~ above listed. This
operation can not be performed by ordinary known distillation
columns but it requires an atmospheric or vacuum fractionator
equiE~ped with a greater number of trays.
To the starting fraction prepared as above is added
0.01 - 5 wt. percent of a Friedel-Crafts type catalyst such as
boron trifluoride, aluminum chloride, and a complex compound
of boron trifluoride and phenol, preferably, boron trifluoride,
boron trifluoride etherate, and boron trifluoride phenolate. -
The resulting mixture is polymerized at a temperature ranging
between -30 and +60C for a period of 10 minutes to 15 hours. ~
Then, the catalyst is decomposed and removed with alkalis such ~ ;
as caustic soda and sodium carbonate. If necessary, the thus
treated reaction product is washed with water, and unreacted
oil and low molecular weight polymers are separated from the
reaction product by evaporation or distillation. The resulting
product is an aromatic hydrocarbon resin having a softening
point of 60 - 120C and a bromine value of 15 or less. It has
excellent resistance to weather and heat. The preferred resin
here has a softening point of 80 - 100C.
It has now been found that if any of the four Lmportant
criteria for the starting fraction; namely, 1) 0.7 wt.% con-
jugated diolefin contene, ~i) 3~ conjugated diolefin content
rate, iii) 2 wt.% indene and its alkyl derivative content, and
iv~ 8% indene content rate, should be neglected, the hydro-
carbon resin resulting from the polymerization of
-- 11 --
1046174
such defective starting fraction will exhibit very poor
resistance to weather and heat, will become yellowish and
when used in a pressure-sensitive adhesive composition, will
be unsatisfactory in respect of the weather-resistance, co-
hesive strength, adhesive streng~h, tackiness and tackiness
life.
The pressure-sensitive adhesive compositions according
to the invention are prepared by blending the above-specified
aromatic hydrocarbon resin with styrene-butadiene rubber (SBR)
or rubbery mixtures chiefly consisting of this SBR. Blending
ratios may vary widely. Generally, the resin may be 20 to 140
parts by weight, preferably 30 to 120 parts by weight per 100
parts rubber. If desired, there may be added various addi-
tives including for example about 0 to 60 parts of a softening
agent, 0 to 60 parts of a plasticizer, 0 to 100 parts of a
filler and 0 to 50 parts of an ageing inhibitor. These parts
may depend upon the type of rubber component used but may
usually be in the range of 0 to 100 parts per 100 parts rubber.
The invention will be further described with reference
to the following examples presented only for purposes of
illustration but not in the limiting sense.
Example 1
The resin component for use in the pressure-sensitive
adhesive compositions of the invention is prepared in the
manner following.
The starting cracked oil previously defined was a by-
product of the steam cracking of naphtha and had a boiling
- 12 -
,
1046~74
point in the range of 140C to 220C. It was analyzed by
gaq chromatography to reveal the following composition:
Composition of Starting Cracked Oil
Polymerizable components (wt. %) --------------- 49.0
Total content of cyclopentadiene and
methyl cyclopentadiene (wt. %) ----------------- 1.6
Total content of indene and its ~- -
alkyl derivatives (wt. %) ---------------------- 8.4
Content of dicyclopentadiene (wt. %) ----------- 0.4
Rate of conjugated diolefin content (%) -------- 4.0
Rate of indene content (~)---------------------- 18.5
The above identified starting cracked oil was charged
via a heater into a first fractionator A-l and thence to a
second fractionator B-l, both fractionators being specified
in the following table.
TABLE II-SPECIFICATIONS AND OPERATING CONDITIONS
OF FRACTIONATORS
Fractionators ------------------------------ A-l B-l
Type of tray ------------------------------- (1) (2)
Number of trays ---------------------------- 30 7
Feed tray (from the bottom) ---------------- 18 4
Feed temperature (C) ---------------------- 108 55
Bottom preS~ure (mm. Hg. abs.) ------------- 120 110
Bottom temperature (C) ------------------- 145 120
Top temperature (C) ----------------------- 93 25
- 13 -
,
- 1046174
Top pressure (mm. Hg. abs) --------------- 68 95
Residence time at bottom (hr.) ----------- 1.0 0.5
Reflux ratio ----------------------------- 5.0 2.0
(1) ----- Sieve
(2) ----- Bubble cap.
The operating conditions of the fractionator A-l had
been chosen so that the overhead fraction of this fractionator
contained a total content of indene and its alkyl derivatives
of 2 weight percent or less and a rate of indene content of 8
percent or less. The overhead product of the first fraction-
ator A-l was thereafter introduced into the second frationator
B-l which was operated also under the above tabulated conditions
so that there was obtained a desired starting fraction from
the bottom of the fractionator B-l in which the total content
of cyclopentadiene and methyl cyclopentadiene was 0.7 weight
percent or less and the rate of diolefin content was 3 per-
cent or less. Con~ugated diolefins were removed from the top
of the fractionator B-l. This opeEatiOn produced 58 parts of
the starting fraction against 100 parts of the starting cracked
oil. The resulting starting fraction consisted of the follow-
ing composition:
Composition of Starting Fraction
Polymerizable components (wt. %) ------------------ 42.60
Total content of cyclopentadiene and
methyl cyclopentadiene (wt. %) -----~ ----------- 0.40
- 14 -
1C146174
Total content of indene and its alkyl ~ ~-
derivatives (wt. %) ------------------------------- 1.00 ~-
Rate of conjugated diolefin content (%) ----------- 0.84
Rate of indene content (%) ------------------------ 2.51 ;
To the starting fraction thus obtained was added 0.5
weight percent of boron trifluoride phenol complex as catalyst,
and polymerization was carried out for 3 hours at 20C. The -
product was washed with aqueous solution of ~odium hydroxide
to remove the catalyst and then washed with water. Unreacted
oil and low polymers were removed from the product by distil-
lation. The resulting resin had a softening poin~ by Ring and
Ball method of 95C, a bromine value of 7 (according to ASTM
.:
D-1158-57T) and a Gardner color of 1 (according to ASTM D~
1544-58T). The resin was blended in amounts of 30 parts, 50
parts, 80 parts and 100 parts by wèight, respectively, per
100 parts by weight of a commercially available styrene-buta-
diene rubber ~SBR). The blend was dissolved in toluene to
make up 20 weight percent concentration.
:,,
Example 2
50 parts by weight of the resin prepared in Example 1
was blended with 70 parts by weight of SBR and 30 parts by
weight of natural rubber, and the whole was dissolved in 600
parts by weight of toluene.
Comparative Examples 1 and 2
The starting cracked oil was subjected to polymeriza-
tlon under the same conditions as in Example 1. A similar
- 15 -
.... . . . . . .
1046174
operation was also carried out with the starting cracked oil
but at a polymeriza~on temperature of 60C. There were
obtained two different resins, one having a softening point of
120C, a bromine value of 12 and a color of 2 and the other
havlng a softening point of 80C, a bromine value of 25 and a
color of 5. These resins were blended each in amounts of 30,
50, 80 and 100 parts by weight per 100 parts by weight of SBR.
Comparative Examples 3 and 4
The procedure of Comparative Example 1 was followed
except that the following resins were used.
Comparative Example 3: "Picolite A"* (softening point
115C), a terpene resin, manu- ~ ;
factured by Esso Chemicals Co.
Comparative Example 4: "YS resin PX1150"** (softening
15` point 115C), a terpene resin,
manufactured by Yasuhara Resin
Industries Ltd.
Comparative Examples 5 - 8
The procedure of Example 2 was followed except that
50 parts by weight of each of the resins used in Comparative
Examples 1 - 4 was blended with the rubber components.
The various pressure-sensitive~adhesive compositions
obtained in the foregoing Examples and Comparative Examples
were subjected to the following tests and the results of these
tests are shown in Tables III and IV.
*Trademark
**Trademark
- 16 -
1046174 ~ ~:
1. Test of Tackiness:
Each of the various adhesives obtained as above was
applied to a polyester film (38 microns thick) to a thickness
of about 30 microns. The coated film was disposed for 25
hours at room temperature of 23+1C thereby making an ad-
hesive tape. This tape was tested for its tackiness by the
J. Dow Ball Rolling ~ethod in which steel balls measuring in
the range of 32/32 inch to 1/32 inch diameter were rolled on
the adhesive tape tilted at an angle of 30 with an approach
run of 10 cm. Largest diameter ball that stopped within an
adhesive area of 10 cm square of the tape was taken as a
measure of tackiness of each particular adhesive composition.
The larger the ball number, the greater the tack, as shown
in Tables III and IV.
~ -
2. Test of Adhesive Strength:
This was conducted in accordance with the provisions
of Japanese Industrial Standards (JIS) Z-1523. The adhesive
tapes prepared as above were cut to 25 mm wide strips and
stuck on a stainless steel panel polished by a water-proof
polishing paper. The force was measured which was required
to peel the strips 180 at a rate of 300 mm per minute.
3. Test of Cohesive Strength:
This test was in accordance with JIS Z-1524 in which
strips of the adhesive tapes measuring 25 cm by 25 cm were
attached to a stainless steel panel fixed in position. The
distance was measured by which the test strip was shifted
under the influence of a 1 kg load applied to the film part
- 17 -
- 104~174
of the tape after a lapse of 24 hours.
4 Test of Tack Life:
The test strips that had been subjected to Test 1
above were further disposed at room temperature of 23+1C for
a period of 7 consecutive days and thereafter again tested
by the procedure of Test 1.
5. Test of Weather-Resistance:
Each test adhesive was coated on a "Cellophane"*
paper to a thickness of 30 microns and disposed at room temp-
erature of 23+1C for 24 hours. To the thus prepared ad-
hesive "Cellophane" was stuck a white paper which was then
radiated by a 15 W. sterilization lamp located 30 cm apart.
Changes of color of the adhesive compositions over a period
of 15 hours were observed with the naked eyes. This color
evaluation was indicated in Table III by the following marks:
-------- Excellent (substantially colorless,
transparent)
O -------- Good (slightly yellowish)
X -------- Bad (extremely yellowish)
It has thus now been found that the pressure-sensi-
tive adhesive compositions provided in accordance with the pre-
sent invention exhibit an excellent balance of adhesive strength,
cohesive strength, tackiness and weather resistance as com-
pared to those prepared in Comparative Examples.
*Trademark for a brand of regenerated cellulose film produced
from viscose by treatment with sulfuric acid and/or ammonium
salts.
- 18 -
?
104~i17
o ~ X ~c X :e X
1` 1` ~
~ m
.,~ ~ u~ o o u~ In o u~ u~ O O
~ O O ~1 _1 O O ~i O O ~i _i
~:
,P~
U~ ~ î o o o o o o O O O O O O
~ ~ a O O ~ O O O u~ O u~ O u~
E~ ~ a~ o o ~ co a~ ~ a~ 1
H ~ U~--. ~i ~ 1 t~l _I ~i
H ~ Z
~3 ~m ~ D u~ ~ O o u~ o
E~-
. ~ ~ .,.
: ~ O O O O O O O O O O O O
. ~ ~ U~ CO
~ _
:
p D l X ¦ 1~ W ~ W
-- 19 --
~04617~
U ~ ~ ~`,) O ~ # ~ ~ .~
~ : '
,~ s~
E~ ~ u~ In o o o o o o . -,
~o~
~ ~s ~ ~Sn O O In o $
.,, ~ . . . .
tn ~ l~1 _1 ~ * * * * o
: s ~
C~ _ o ~.
E~l O 3 ~
E~ .~ ~ , .
~ ~ ~ O O O O O O O O ~
E-~ ~ ~ Ir) o 11'~ u~ ~1
'~~ ~. ~ ` , U ,'' '' .
H O a~ : :
H -- ~ Z
~m ~r o u~ O O O O o ~ ~
~ o O O O O O O O ~ ~ ~
. ~ 3 ~ ~
X
:~
~ ~ ' ~ a) ~ ~ ~
~ ~ ~ 1 C,~
-- 20 --
104~174
TABLE IV: TEST RESULTS
A & esive Cohesive
A &esive Tackiness Strength Strength
Compound (Ball No.) (g/25 mm wide) (distance of
tape shift)
- (mm)
Example 2 13 1,400 0.0
Comparative
Example 5 0 1,150 0.0
Comparative
Example 6 5 1,100 0.5
Comparative
Example 7 19 1,050 1.0
Comparative - .
Example 8 7 1,250 1.0
-
.
...
.
