Note: Descriptions are shown in the official language in which they were submitted.
~7~927
The present invention relates to the stabilization of
organic polymers.
In particular it relates to a new group of polysil~xanic
stabilizing additives containing sterically hindered phenol
groups in the molecule, the procedure for the preparation of
these stahilizing compounds and the stabilized polymeric
compositions.
It is ~nown that organic polymers are inclined to degrade
over a period of ~ime due to exposure to atmospheric agents,
and that they are also easily subJect to degradation during
operating and transformation processes owin~ to the high
temperatures reached.
This degradation is reflected in a decrease o~ the
physical charac~eristics o~ the polymer, such as, for 2~ampl2,
a decrease in the breaklng load and ln fle~ibility, and with
alterations in the optlcal propertles o~ the ~nd product.
To counteract these forms of degrada~ion it i~ common
practice to introduce stabilizing compounds lnto the polymer.
A group of compounds which is widely used for this purpose ls
that of s~erically hindered phenol~
The probl~ms ~hich arise in the s~abilization o~ organio -~
" ` ~ ; ' ' ' "~' . , ';
2~77~f~7
polymers ba~ically derive from incompatibility b~tween polymer
and stabilizer and the discharging of the stabilizer from the
polymer. It is therefore necessary to have stabilizing
compounds which are as compatible as pc~ssible wi~h the polymer
to be stabilized, and which are capable of remai.niny inside
the polymer.
U.S. Patent 4.888.375 and European Patent Application
182.415 describe sterically hindered phenolic antioxidant
additives having a hydrolizable sillcic function in the
molecule.
These compounds, after hydrolysis of the sililated
function, are capable of interacting among each other or with
a solid support, producing complex resinous structures capable
of remainlng for a period of time inside the oryanic polymer
in which they are incorporate~.
In addition, stabilizing compounds of a polymeric nature,
including sterically hindered phenol groups attached to the
silicon atoms of a polysiloxanic chain are described, for
example, in U.S. Patents 4 . 430 . 235 and 4 . 879 . 378 .
However, eve~ if the incorporation of the st~bilizer in
a polymeric structure allows for its homogeneous m~ing inside
~he polymeric materials ~o be stabilized, and this
inco~pora~ion is capable of remaining inside the polymer for
~ period of time, ~here are certain partlcular cases when
these stabilizers do not g~ve sufficient guarantee for the
, ~
-;
'
~77~27
uses or w~ich they are destined.
This is the case, for example, when the end products are
destined to come into contact with particular substances or
solvents which are capable of extractlng the stabilizing
siloxanic polymer, or to come into contact with food when the
total non-mi~ration of the add~iYe towards the surface of the
product must be guaranteed.
A new group of stabilizers which overcomes the above
disadvantages has now been surpris$ngly found.
The present invention consequzntly relates to a new group
of stabilizing compounds o~ a polymeric nature composed o~ a
polysiloxanic chain having, besides sterically hindered phenol
groups, reactive organic groups capable of chemically binding
themselves to the polymeric structure to be stabilized.
The present invention also relates to a process for the
preparation of the above polymeric sta~ilizers.
Furthermore, the present invention relatP~ to polymeric
compositioas containing an organic polymer and a stabilizing
quantity of the above polymerlc stabilizers.
In accordancP with this, the first aspec~ of the present
invzntion relates to polymeric stabilizing compounds having
the following formula:
MX~YpZqM~ (I)
wherein
2~77927
Il'
X ~ --o--si-- ~ --03/2SI--
R2 ~z
E~L
Y = o $i or _o3~2SI -
R~ R~
z = -O-Si-, -O3/2SI - or -O~2Si-
R~
~'
M ~ Rn-Si-, ~, R3,
R'
M'- -OM,
M and M' can optionall~ form together a direct bond ~hus
produclng a cyclic structure,
Fl is a phen~l or a line~r or branched alkyl radical
containing ~rom 1 to 20 car~o~ atoms,
F~ is a reacti~e organic group capabla of chemicall~ binding
itsel~ to the polymQric ~true*ure to ~B 8~biliZ8d,
R3 is a linear or branched alXyl radical cont~ining from 1 to
6 car~on ato~s,
R~ is a rad~c~l ~el2c~ed from the group i~cludlng:
R5 ~ :-
~ ' ,
. .
~77~7
RC 3,
R5 ~ (0)n~-R8 -
R6 OE
wherein,
F~ and R6, ~he sa~e or d~fferent, are al~yl radicals, linear
or branched, con~aining from 1 to 10 carbon atoms,
R7 ls an akyl ne radical, llnear or branched, containlng from
3 to 10 carbon atoms,
R8 is an alkylene radical, linear or branched, containing from
1 to 10 carbon atoms, or a biradical selected from -R~-COO-R1o~,
-R~-coo-Rlo-s-Rll- and -R~o~S~R~
R~, Rlo and Rll, the same or different, are alXylene radicals,
line~r or branched, containlng ~rom 2 to 10 c OE bon atoms,
R' is a phenyl or an alkyl rad~cal, line æ or branched,
containing ~rom 1 ~o 10 carbon atoms,
RN is oqual to R', R~ or R~,
m, p, the same or differen~, are integess from 1 to 50,
q is an integer betwe~n O ~nd 50,.
n is equal to O or 1.
R~ is pr~ferably selected from radic~l~ cont~inlny a
car~on-carbon doubl0 bond, an epo~ rin~, a sulphide group, or
an aminic gr p.
- 6 -
~77g27
~ ore preferably, R~ is a radical selected ~rom the group
including:
. C~I2=CH-
C}I3
C~2=C-cOO~ 2) 3
~0~
C~I2--C~ --( CH2 ) 3-
~IS--( CHz ) 3
}IZ~- ( CH2) 3-
-V
When R~ is an alkyl radical, it preferably contains from
to 10 car~on atoms t and even more prefera~:11y fro~ 1 to 3
carbon atoms. Particularly preferred is the case where R~ is
methyl .
Rs and R,S are preferably braslched, and even more
preferably are t-~utyl radicals.
The stabilizing compound~; o~ ~he pr~ent invention are
polymers having a rando~ distribution o:e ~os o~ic units X, Y
and Z.
They ~ay also have hydro~ r alko~yl gro~ps oll 'che
silicon ato~ whid ar~ ~ot hown i~ t:h~ ge~eral ~orl~ulae
given.
The co~pounds corresponding to genoral fomlula (I) can ba
: , , " . , ~
,
2~77~,~7
obtained, ~or example, by the reaction of a mixture of
compounds having the following formulae:
(R~ )n
Si-(R~)3-n (II)
R~
(R~ )n
Si (R~ I I )3-n (III)
R"
optionally in the presence of compounds havin~ the following
formulae:
(R~.)r
li--(R~ ~ )4-r (IV)
R~
R"--Si--R" ' (V)
wherein R''' is 0~ or C1, r is equal to 0, 1 or 2, and ~, F~,
R~, R', Rn, and n have the meaning prev~ously defined.
The compounds having formula (II), (III), (IV) and (V)
hydrol~ze under ~land conditio~s generating ~llan31~ whiCh ca~
be conden~ed among each other to form polysiloxanic structures
which are more or less complex depending on the ~umber o~ R'''
group~ linked to the silicon a~om.
By suitably varying ~he ratios b~tween ~he compounds
having formula (II), tIII), (IV) and (V) which are reacted, it
-- 8 --
- . . .
- : . - - . :. , .
:
2~7~92~
is possible to vary the m, p, q values in the compounds having
formula (I~ obtained.
In ~articular, depending o~ the quantities us~d o~ a
compound having formula (V), which acts as chai~ terminator,
products can be obtalned with structures more or less comple~
and with higher or lower molecular weights.
The above hydrolysis and copolymerization reaction is
carried out in water or in a mi~ture of organic solvent and
water in ratios of up to 10:1.
When in the reagents having formula (II), (III), (IV) and
(V), R''' is equal to OR3, the process is carried out at a
temperature ranginy from 20 to 100C for a period of 2-20
hour~, until the complete hydrolysis of the reagents. At this
stage the polymerization reaction is carried out at the
boiling point of the solvent, in the presencs of a
condensation catalyst, eliminating the reaction water and
alcohol by distillation. The reactton is then continued at
reduced pressure (0.1-50 mm Hg ) at temperatures ranging from
60 to 140C. The polymerization reaction generally requires a
period of 2 to 10 hours.
When, on the other hand, R''~ is equal to Cl, the
reaction is carried out under stirrlng at tamperatures ranging
from 20 to 120~C for a period of 1-~ hours. The product is
recovered from the organic phase after eliminating the solvent
by distillatlon at reduc~d pressure.
'
~7~27
Comm~tcial products such as vinylmethyldichlorosilane,
vinyltriethoxysilane, 3-mercaptopropyltrimetho~ys~lane, 3-
.--glycldyloxyproyltrimethoxysilane, 3-methacryloxypropyltri-
chlorosilane, 3-aminopropyltriethoxys;ilane, may be used as
reagents having formula (II).
With respect to the reagents havin~ formula (II~), these
can be synth~sized, for example, as described in U.S. Patent
4.888.375 in the name of same Applicant.
Examplss of alko~ysilanic compounds having formula (III)
are those having the following formulae:
t OC~2C~3
~ ~ (CH2)2COO(CX2)3S\-CX~
t . C~2c~3
HO~ ( C}I2. ) 2 COO ( C~2 ) 3 S i- ( C~2 C~3 ~ 3
oC~I2CX3
~ /
xo~coo (c~2) 3si\C~3
t OC~2C~3
t
1~0~(~2)3Si~(C~3~3)3
t ~ ~C~C~3
~O ~(C~2)3Sl\~3
t - 10 - OC~2C~3
-
2~77~27
t.
r.O~ (C~2 ) 2COC ( CE~2 ~ 3 ~5~ (C ~I2 ) 3Si- tOC~;3 ) 3
t __
wherein t is a ter-butyl radical.
Commercial products such as dimethyldichlorosilane,
diphenyldichloro~llane, dimethyldietho~y~ilane can be used as
reagents having formula (IV).
Co.~ercial products such as trlmethylchloros~lane,
trimethylethoxysilane, vinyldimethylethoxysilane ~ay be used
as reagents having formula (V).
The organic solvent is selected rom the group lncluding
ethers, s~ch as tet~hydrofuran (THF), alcohols such as
ethanol, aliphatic hydrocar~ons, such a~ heptane, alicyclic
hydrocar~ons, such as cyclohe~ane, or aromatic hydrocar~on~s,
such as toluene.
Condensation catalysts s~rhich can be used are, for
example, dibu~yltindllaurate, zinc octancat , t$n ~ctanoate or
an alXallne hydro~ide. ~he concent~;~tion of the catalyst ~ s
wit~in the ra~ge of O.OQ5-t).5~ by w~ight ~rith r~spec~ to th~
reagents charged.
ThQ ~oly~ additi~3 of the present l~enti a~
character~zed ~ at they have a s~ctl~re fus~ whlch i~
capable o:E lin}~g to the polymerlc ma~ or to t~a
reinforc:~g materlal o t~e plas~ic product o~ e ~e~.,
thU5 pr~v~nt~ng the. s~llizer from belng discharged from the
matrix or improving the adhesion between matrix and support.
As said before, these characteristics, together with the
capacity of delaying the degradation of the polymers, are
particularly important when the non-migration of the additive
and lts non-extractability with sol~ents, fats or soaps are
required.
This is the case, for example, when polymeric end
products are destined to come in contact with food, or in the
stabilization of polymeric mixtures or copolymers, or also for
the production of composite end products composed of
multilayers of organic polymers or polymer and inorganic
support.
In this latter case, in fact, the migration of the
additive almost always causes a detachment of the various
layers, a loss o~ mechanical characteristics of the product
and a more rapid degradation of the oryanic material.
The siliconic products of the present invention are
generally added to the organic polymer to be stabilized in the
compounding phase.
More generally the stabilizers of the present invention
are added as additives either in th~ final phase of the
syn~hesis process or in the production phase of the end-
products.
The most widely used me~hod is to add the products in the
preparatory phase of the end-product because i~allows for the
- 12 -
' ' ' ' ' `
2~77~7
level of addition to correspond to the characte-istics o~ the
product to be obtained.
. The polymers to be stabilized can be polyolefins (LDPE,
LLDPE, HDPE, PP) and their copolymers, the copolymers o~ these
with acrylic acid or maleic anhydride, polyesters, polyamides,
polycarbonates, polyurethanes, terpolymers EPDM and ABS,
svnthetic rubbers.
One of the applications o~ this technology is the
production of products made of low density polyethylene (LDPE)
cross-linked during the extrusion phase.
When the additive of the present invention has R2 groups
containing a double reactive bond or a sulphide group, the
grafting o~ the additive to the polymeric matrix takes places
owing to the formation of radicals, and can possibly be
induced by the presence of small quantities of organic
peroxide during the operating phase of the polymeric material
~t high temperatures.
The stabilizers of the present invention may additionally
contain one or more additives selected, for e~ample, from
antioxidants, heat and light stabilizers, metal disactivators,
basic co-stabilizers and nuclea~ing agen~s.
In particular, they can be used in combination with
additives based on sterically hindered amines, such as those
corresponding to the trade-names Uvasil 299, ~inuvin 770,
Tinuvin 622, Chi~assorb 944, or phosphites andJor phosphonites
- 13 -
~ ' ' ' ' ' ' ' ! ,~'
.. ',..,' '"' ' ' ',`,
~
2~77~7
such as those corresponding to the trade-names Ultrano~ 626,
W~ston 618, Alkanox 240, Sandostab PEYQ, or organic compounds
containing sulphur such as distearyl thiodipropionate and
dilauryl thiodipropionate.
The quantlty of silioonlc additive nonmally used varies
from 0.05% to 1~ by weight o~ the weight of the resin to b2
stabilized. The preferred quantlties vary from 0.1~ to 0.8% by
weight of the welght of the resin.
The fo~lowing examples provide a bPtter illustra~ion of
the present invention but do not limit it 1~ any way.
EXAMP~E 1
PreDaration of a stabilizer corresDondlnq to the followina
formula:
C~3 C~3
M(o-si )m~(o-li-)p-M
IX (I 2)3--C-(c~2)2
CX2 t
wherein M is H or C~3CX~-, M' $s OH or C~3CH20- ar~ t is ter-
butyl.
~ 5.0 ml of ethanol, 11.1 g (O.025 moles) o~ a co~pound
having formula (III) ~herein R~ is methyl, ~ ls e~hyl and R~
_ . . . . _ . . _ . . . . . .
is ~ (CXz~COO~CXz~3-,
t
- 14 -
,,: ' ~ ' ' '`
2~37~27
1. o ml of diethoxy methylvinylsilane and 5.0 ml of H2O are
charged into a flask equipped with a stlrrer, cond~nser and
.~hermometer.
The solution ls kept at 65C until gas chromatograhic
analysis no longer reveals the presence of the reagents, i.e
for about 3 hours.
The ethanol is then removed by di.stillation, 0.05 ml o
dibutyltindilaurate are aaded and the mixture ls brought to a
temperature of 120C at reduced pressure (5-12 mm Hg) for a
pPriod of 3 hours.
A colourless resinous product is obtained, having an
average osmometric molecular weight o~ 1300 Da, and whose IR
and NMR spectra are consistent with the structure indicated,
with a ratio m/p=0.2.
E~AMPLE 2
Preoaration of a stabilizer corresPondin~ to the followina
formula~
1 3
M(o3/2-si-)m~(o~ )p-~ ~ t
CH (C~)3-C-CO-(c~2)2
Il .
C~2 t
wherein M is H or C~3CH2-, M' is O~ or C~3C~20- and t 1 ter-
butyl.
20.0 ml o~ ethanol, 11.91 g ~0.026 moles) of a co~pound
having formula (III) wherein Rl ls methyl, R3 i~ ethyl and R7
,
2~7~7
is t
7~o ~ (CH2)2coo(cH2)
O.50 y (0.0026 moles) of triethoxyvinylsilane and 3.0 ml o~
HzO are charged ~nto a flas~ equipped with stirrer, condenser
and thermometer.
The solution is kept at 55~C until gaschromatographic
analysis no longer reveals the presence of the reagents, i.e.
for about 5 hours. It is then left overnight at room
temperature.
The ethanol is then removed by distillat~on, 0.04 ml of
dibutyltindilaurate are added and the mixture is brought to a
temperature of 100 to 130C at reduced pressure (up to 0.4 ~m
Hg) for a period of 3 hours.
9.87 g of a resinous produ~t are obtained, whose IR and
NMR spectra ar~ consistent wi~h the structure indica~ed, with
a ratio m/p=0.1.
E~U~PLE 3
Pre~aration of t e same_s~abllizer as E~amDle 2
The same procedurP i~ n~ed a~ descr~b~d in Example ~, but
charging 9.85 g of the com~ound ha~ing formula (III) and 1.10
g of trietho~yvinylsilane.
8.36 g of a re~inou~ product are obtai~ed, ~hos~
structure corIesponds t~ that of the product of E~ampl8 2,
- 16 -
.
;, ~ , , , ;
,.. . . ..
'
2~77~2~
with a ratio m/p=0.2.
EXAMPLE 4
Preparation of the~same stabilizer as ExamDle 2.
The same procedure is used as described in Example 2, but
charging 11,67 g of the compound hav~ng formula (III) and 4.93
g of triethoxyvinylsilane.
11.70 g of a resinous product are obtained, whos~
structure corresponds to that of the product of Example 2,
with a ratio m/p=l.O.
COMPARATIVE E2AMPLE A
Preparation of a stabi}izer correspond~nq to the followina
formula:
H3
~(o-Si-)p-~' t
(I ~)3-0-C~-(C~ )2 ~ ~
wherein M is ~ or CH3CH2-, M' is 0~ or C~3C~20- and t is ter-
b~tyl.
20.0 ml of ethanol, 5.0 ml of ~20 and 9.42 g of a
compound havi~g for~ a ~III) wherein Rl i5 methyl, R3 is ethyl
.. ._ ... . _ . .
and R~ is t
~ (C~2)2~00(C~)3-
æ e charged Into a flask equipped wi~h a qtirrer, condenser
and thermometer.
- 17 -
~ . . . .
2~7~2~
The solution is kep-t at 60C for about 2 hours. The
ethanol is then removed by distillation, 0.02 ml of
dibutyltindilaurate are added and the temperature is brought
to 120C at reduced pressure (4 mm Hg) for a perlod of 3
hours.
8.21 g of a colo~rless resinous product are obtained,
having an average osmometric molecular w~ight of about 1800
Da.
EXAMPLE 5
Pre~aration of a stabilizer correspondina to the follow~nq
forsnula_ C~I
l'3
~03/2-fi-, m~(o-si-)p-~- ~ CX3
CH (CH2)3 ~ r
C~2 CH3
wherein M is ~ or CX3CH2-, and M' is OH or C~3C~20- .
20.0 ml of e~hianol, 6. a g ( o . 020 moles) o~ a compound
having formula (III) wherein Rl is methyl, R~ ~ ethyl and R~
_ . . .
is
C~3
~I0~ (C~2) 3 '
.~,~
3.8 g (Oo2 moles) of trletho~y vi~yl~ilane and 3.0 ml of H20
are charged into a flask equipped with a stirrer, condanser.
and thermometer.
- 18 -
: . : . . , : ,,~ ,
2~7~27
The solution is kept at room temperature until
gaschromatographic analysi-~ no longer reveals the presenc~ of
the reagents, i.e. for about 20 hours.
O.05 ml of dibutyltindilaurate S~re then added and the
ethanol is slowly removed (4 hours) by distillat~on. ~he
temperature ls brought to 120C at reduced pressure (u~ to 5
mm Hg) for a perlod of 3 hours.
6.53 g of a resinous prod-~ct are obtained, having an
average osmometric molecular weight of 2500 Da, whose NMR
spectrum is con~istent with the structure indlcated, wlth a
ratio m/p-lØ
EXAMPLE 6
Preparation of a stabilizer correspon~inq to the followin~
formula:
H3 :
~(O3/2-si-~m-(o-si-)p-M' t
CN (CH2)3-O-CO ~ H
CX2 t
wherein M is H dr CH3cH2-, M ~ is 0~ or CH3~0- and t is ter-
butyl.
20.0 mi of ethanol, 5.60 g (O.013 ~oles) of a compound
having formula (~II) wherein Rl i~ methyL, ~ is ethyl and R~
. _ . . .. .. .. _ . _
is t
(c~2)3
t
-- 19 --
~7~7
2.47 g (O. oi3 moles) of triethoxyvinylsilane and 3.0 ml of H20
are charged into a flask equlpped with a stirrer, ~o~denser
and thermometer.
The same procedure is used as described in Eæample 2.
6086 g of a glass which can be broken into a solid white
product , are obtained, whose IR and NMR spectra are
consistent with the structure indicated, wlth a ratio m/p~.O.
EXAMPLE 7
Preparation o~ a stabilizer corresPondina tn the followinq
formula:
CH3
~(03/2-si-)m-(o-si-)p-Nl t
(I 2)3 (CH2)~-0-cO-(c~2)2
SH t
wherein M is H or CH3C~2-, M' is OH or CH3CH20- and t is ter-
butyl.
20.0 ml o~ ethanol, 7.98 g (0.017 moles) of a compound
having formula (III) whereln ~ is methyl, R3 is ethyl and R6
~s
HO ~ (C~2~2COO(c~2)3-r
3.5 ml (O.017 moles) of 3-mercaptopropyltrimethoxysilane a~d
4.0 ml of H20 arQ charged into a flask eguipped wi~h a
stirrer, condenser and the¢mometer.
- 20 -
, , .
, ' . ': . ~ ' ~
. .::
2~77927
The solution is kept at room tempera-ture until
gaschromatographic analysis no longer reveals the presence of
~he reagents, i.e. for about lO hours.
The ethanol is then removed by distillation, and 50 ml of
toluene and 0.02 ml of dibutyltindilaurate are added. The
temperature is brought to 110C for a period of 3 hours while
the water is azeotropically eliminated. The toluene is then
removed by distillation and the residue is treated for 1 hour
at 120C under vacuum.
9.35 g of a resinous product is obtained whose IR and NMR
spectra are consistent with the structure indicated, with a
ratio m/p=lØ
EXAMPLE 8
Pre~aration of LDPE stabilized with the com~ounds of the
invention.
Masters of commercial LDPE of the Riblene CF 2200 type
with 10% by weight of stabilizer were prepared with the
stabilizing compounds prepared as described in Examples
1,2,3,4 accor ing to the following procedure.
The stabilizing compound is dissolved in toluene; LDPE in
powder form is added to this solution, and the solvent is then
removed by evaporation at reduced pressure under stirring.
The masters t~us prepared are mixed with further
commercial LDPE of ~he Riblene CF 2200 type to obtain mi~tures
containing 0.2~ by weight of stabilizer~
- 21 -
~77~f~37
Each of these mixtures, to which 2,5-dimethyl-2,5-
di(terbutylperoxy)hexane up to 0.015~ by weight has been
added, is extruded ln a Brabender l.aboratory-~ype extruder
with 50 rpm of the screw, and with the following temperature
profile fro~ the head zone to the tail zone: 155-160-170-
170C.
The samples thus eætruded are cut into pellets and
pressed for 3 minutes at 200C, to obtain sample plates having
a thickness of 0.5 mm.
Using the same procedure but without peroxide, LDPE
sample plates were prepared to which the compound of
Comparative Example A, ANOg 20 or ANOX PP18 were added. The
two latter products are. commercial additives containing the
sterically hindered phenol group.
The sample plates thus prepared were extracted in soxhlet
with acetone for 10 hours and with 1,2-dichloroethane for 7
hours.
The relative quantity of antioxidant remaining after the
extraction treatment is evaluated on a first series of sample
plates by IR measurements. The relative absorption variation
is calculated at 1735 cm~~ compared with a non-stabilized
sample (TQ), and the remaining percentage of antioxidant is
expressed as:
Æ - A/Ao x 100
where Æ is the extraction resistance and Ao and A are the
- 2~ -
,: .
.. : .
~ ' ,
~77~27
absorption values respectively before and after the extraction
treatment. The results are shown in Table 1.
To verify the stabilization of theitest samples after the
extraction treatment, a second series of sample plates was
submitted to prolonged thermal treatment in an oven with air
circulation at 100C. The degradation process was observed on
the basis of the formation of carbonylic compounds revealed by
IR measurements. In particular, the index valuei o~ car~onyl
(ICo) is calculated, expressed as:
I~ ~ Al7lo~-l/Alsss~-l
The induction time ls determined from the ICo values. A
greater effectiveness of the stabilizing action corresponds to
a high value of the induction time. The induction times of the
non-extracted (TIo) and extracted (TI) test samples are shown
in Table II.
TABLE I
, ,. . . ~ ~ i
~ m/p R~
Example 1 O.2 63
Example 2 0.1 70
Example 3 0.2 77
Example 4 1.O 93
Example A (comparison) O S0
ANOX 20 / ~0
ANOX PP18 / ~ ~ r
_ ~
- 23
.: : ~ : .
i, , .
' ~
2~77~27
TABLE II,
. ~-- . ___
S A M P L E m/p~Io(h) TI (h)
_ _ .___ _ __
TQ ~ . / 10 10
Ea:a~nple 1 0. 2 1650 920
Example ~ 0.1 1100 6~0
Example 3 O . 2 750 640
Example 4 1. O 630 500
Example A ( comp~rison ) O 1500 550
ANOX 20 / 1300 130
ANO~ PP18 i 1700 10
' ___. ___ ~
. . .. . . .
.
: . . .,; . .-
. .
- .: , . -~ . :
,~
'' ' . ' ,'
~ ', ' . . ~
