Note: Descriptions are shown in the official language in which they were submitted.
WOgS/34604 2192~ 11 P~ 3~; ~97
D~GT~ AnARI,T' POI.YMERS AND POIIYMER PRODTTCTS
CROSS~ N~ ~ TO RT~T~ATED APPT.I~'ATION
This is a continuation-in-part of Application
Serial No. 08/258,280 filed June 10, 1994 which is a
~ nt;ntl~tion of Application Serial No. 07/867, 718 filed
July 9, 1992 now U.S. Patent No. 5,321,065 issued June lg,
1994 .
BACE~GROUND OF THE INVENTION
Polymer blending has become one of the most
commercially important and inPYp~nctive ways of developing
new ~tf~; i3~ ~: from readily available base polymers. The
main aim of polyblending is the production of good
performance materials at a reduced c06t or the
modification of some specific properties of polymers. This
is achieved through the infinite hlf~n-lin~ possibilities,
the ability to use existing fl~ ;hl~ processing equipment,
and the capacity to combine expensive polymers with
ordinary and abundant ones.
Polyethylene is produced by polymerizing
2 0 ethylene gas and the result is a j oining together of the
ethylene molecules into long polymer chains. The most
common additives are heat and light stabilizers, slip,
antiblock and antistatic agents, flame retardants and
Wo 95/3 4604 ~ J .. 7
2192~
-2 -
pigments To protect against thermal n~ ; nn which can
be a problem during processing, antioxidants are usually
added Photo or light oxidation that occurs when natural
PE is exposed to W r~ t;~n is most often inhibited by
the addition of carbon black and/or W stabilizers.
PE is classif ied as either low and medium
density (LDPE and LLDPE) or high density (linear) PE
(HDPE) based on ASTM designation. LDPE and LLDPE have been
used in several applications: f ilm and sheeting,
housewares, closures and ~nnti~;n~rS~ packaging materials,
wire and cable coating, rotational molding, powder
coating, pipe extrusion, refuse or garbage bags and
extrusion coating The primary proce6sing techniques used
to convert HDPE into end products are blow and injection
molding for ~nnt~in~rs and lid closures, films and large
f~nnt~ i n~rS .
Ethylene(vinyl) acetate (EVA) copolymer is
generally obtained by adding vinyl acetate to PE. EVA is
tougher, more flexible, softer and less heat resistant
then LDPE 13eing softer and more flexible than PE, the
copolymers are of ten competitive with rubbers and
plasticized ~VC. At higher levels of Co~nn~
incorporation, the EVA' s are used as t~ax additives and as
^~tF: in other formulations for hot melt coatings and
adhesives In these applications, the copolymers provide
strength, improved barrier properties and better
processing characteristics.
WO 95/34604 ~ 97
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--3
Polypropylene (PP) in its natural form is
particularly vulnerable to degradative attack by oxygen
and sunlight . St~h; 1; 7F'rS have been developed which allow
- PP to retain its balance of good mechanical properties at
low cost, and to do so in severe envi., tq~ Phenolic
antioxidants have the primary function of reacting with
the polymer peroxy radicals to form more stable radicals,
and thus stop the chain oxidative attack. To protect the
polymer against long periods of outdoor exposure to W
radiation, W a~sorbers are added before processing. These
absorbers are colorless and transform W radiation into
harmless longer wavelength light. Common classes of W
additives include the b~on7~rh~nr~nf~q, benzotriazoles,
salicylates, and phenyltriazines. Certain nickel salts
also provide some degree of W absorption and act as a
free radical scavengers, preventing the prop~t;~n of the
photo-chain degradation process. PP finds Arpl;r~t;~m~ in
molded products for automotive and appliance uses,
r~k~;n~, fibers and fibrillated films, microporous
filters and ~ ;n;7ation eq-l; R, spun fibers, film
and sheet and nonwovens.
Styrene is used primarily for the ~-n~lf~-t~re Of
th~ tic resins, of which polystyrene (PS) and
polystyrene copolymers are the most important. Polystyrene
is the third most widely used thermoplastic resin,
surpassed only by PVC and PE. Most polystyrene is
.
Wo 9~/34604 1 ~ """ c~ 97
2i921~1 ~
--4 --
processed by rotational and injection molding, extrusion
and thermoforming. Two types of polystyrene are currently
used: crystal and impact polystyrene. Both types find uses
in houseware applications, packaging, appliances, wall
coverings and many specialty applications.
PVC is the most highly I ~l;f;Ah~e plastic known.
Products can be formed with a broad range of mechanical
properties. Being self-extinguishing, PVC also has
inherer~t flame resistance. Plasticizers such as phtahlates
and adipates contribute to its flexibility. The feel of
PVC is controlled by the amount of plasticizers and/or
filler material, as well as the type of resin. Impact
modifiers can be ;nrlll~P~i to increase breakage resistance.
~Jnder W irradiation, and in the presence of
oxygen and moisture, PVC undergoes a very fast
dehydroehlorination and perr~ t; nn proeess with the
formation of polyenes and subse~uent scission and/or
crosslinking of the chains Additives which have W
stabilization effeet ean be ;nr1~l~Pd to prevent
degradation in sunlight. One sueh stabilizer is t;tAn;~
dioxide (TiO2) which provides ader1uate proteetion for most
purposes and i8 most of ten introduced at levels up to 10
to 12 phr. ~t these levels, TiO2 can enhanee the
weathering properties of PVC produets beeause of its
ability to absorb to a certain degree W rArl;Atirn falling
on the polymer Ti02 is widely used in white and light
co o~ formulat~on~.
WO 95l34604 P~1/IJ~ 97
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Tio2 is approximately 509~ more costly than
unplasticized PvC used f or outdoor service and PVC
producers are looking for ways to reduce their TiO2
consumption .
Current thermoplastic polymeric materials are
generally disposed of by incineration. They can also be
disposed of by recycling which can be achieved by
increasing their oxidation temperature. Increasing the
oxidation temperature can be achieved through the use of
additives. Such additives have generally been known to
have certain other drawbacks as when such materials must
be incinerated, such additives generate toxic fumes
necessitating an additional treatment step which
increases the overall cost of ~; ~p..c~l . In any event, with
PVC, additional treatment for ~fflll~nt gases is necessary.
Certain thermoplastic polymeric materials can
either photodegrade or biodegrade. Generally,
photodegradable thermoplastic polymeric m~t~ l C are
~ht~;n~ by introducing photoactive additives into a base
r-t~ 1 such as for example polyolefin. These additives
consist of molecules ~r)ntA;n;ng oxygen and/or heavy metals
which play a role in the initiation and f-~rm-ti~n of free
radicals under the action of ultraviolet (W) r~ t; c~n .
The free radicals cause a rupture of the chains of the
polymer and therefore make the polymer fragile and
mechanically ~egradable.
Wo95/34604 P~~
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--6--
Although fre~uently in use, such photoactive
additives are generally strongly oxidizing which can cause
the degradation of the plastic material to begin
- immediately after the manufacture of the material thus
reducing the shelf life of the th-rm~-rl ~RtiC polymeric
materials .
Generally, biodegradable plastic materials can
be obtained by the introduction of a biopolymer such as
6tarch As starch can be attacked by microorganisms, the
material becomes susceptible to degradation
However, the incorporation of starch in such
material can have drawbacks as it can be partially
decomposed during the processing and it is highly
sensitive to water. Furthermore, starch i8 not compatible
with moRt polymers, and its incorporation during polymer
m-r,.-f~l-t~re can render the final product brittle.
Furthermore, in polymeric ~ilms with a particularly small
thickness, the particle size of starch can be a limiting
factor on the overall manufacturing process and the cost
becomes prohibitive.
A nu~ber of biopolymers in addition to starch
can also be used such as for example other carbohydrates
with one major drawback that upon blending with the
polymeric material, the biopolymer can undergo various
alterations such as oxidation and polycondensation Such
alteration to the biopolymer can have a negative effect on
the mechanical properties of the polymeric materials
Wo95l34604 r~ J~ ~97
- 2192111
--7--
As an alternative to the foregoing, a biopolymer
8uch as organosolv lignin can be incorporated with
thermoplastic polymeric materials
SVMMARY OF TXE INVENTION
This invention provides for degradable polymers
and polymer products having incorporated therein an
organosolv lignin The incorporation of the lignin
enhances the mechanical properties of the polymers while
causing them to~ degrade under certain conditions. The
polymers of this invention can be disposed of without
incineration or recycled, resulting in a savings in energy
and minimal pollution.
DESCRIPTION QF T~E ~ J EM~OI:IMENTS
The biopolymer employed in this invention is a
lignin which is separated from plant biomass by a novel
chemical delignification technology based on organic
solvents, for example ethanol. ~n~rillly referred to as
organosolv lignin, it is a free-flowing, non-toxic powder
It is soluble in aqueous alkali and in selected organic
solvents. It is generally char~c-t~ c~ by its
hydrophobicity, purity, melt flow properties and a low
level o~ carbohydrates and inorganic ~ nt~m;n~ntc,
WO 95/34604 219 2 ~ .. r ~~97
--8--
The lignins of this invention can be
incorporated into various polymeric materials and can have
various effects on the polymeric blend such as for example
they can function as an antioxidant, as a stabilizer
against ultraviolet radiation and can enhance the
mechanical properties of these materials.
The lignins of this invention can stimulate
degradation of the polymeric materials when photoadditives
are added to_ the blend. The products can degrade by
photodegradation of the polymeric materials and the lignin
or alternatively by bior~ rAtlAt~ n of the lignin under
composting conditions.
The lignins of this invention can be blended and
, '^~ with polymers such as for example polyethylene,
polypropylene, poly(vinyl) chloride and poly:.Ly~ e
copolymers in a weight ratio of from about 0.5~ to about
40~ with the polymer of choice. The blends can be then
processed by extrusion, calendering, in~ection or known
processes in the art to yield articles of manufacture
having different utilities such as for example, film and
molded products. Alternatively, the lignin can be blended
with a copolymer such as for example ethylene(vinyl)
acetate or styrene-blltA~ n~A copolymers. The resulting
blend is a master batch which can be diluted by further
2~ hl~n~q;nj with polymers such as for example polyethylene,
polypropylene~ poly(vinyl) choride and polystyrene
copolymers The blends can be processed using known
methods in the arts to yield the desired final products.
W0 95/34604 2 ~ 2 P~ 97
g
In a preferred ~^mhn~;r^nt, a master batch can be
prepared by mixing with organosolv lignin of from 359~ to
about 859~ on a weight basis with the copolymer of choice
such as EVA, sss or any other polymer which is known to
have a glass transition temperature in the same range as
that of the lignin. The master batch can be prepared by
mixing all ingredients directly or in successive stages.
For specific applications, the master batch can
also be coextruded with a polymer of choice depending on
the desired final product. Pellets can be produced with a
core and a sheath with a variable composition. The core o_
the pellet can have the composition of the master batch
while the sheath can have the polymer composition of the
;nti~n~ final product. The pellets can generally be
~ht~;n^d by gr^nlll^t;n; the f; 1 Am^-ltq coming out of the
extruder .
The core of the pellet can be manuf actured by
^nnR;~^r;nj the nature of the biopolymer to be
incorporated therein. When organosolv lignin is used, the
pellet can be manufactured without causing any ~^h^mi~ l or
physical deter;~^~r~t;nn by mixing the lignin or a master
batch polymer of particular interest such as for example
EVA or SBS or any other ma9ter batch polymer which is
known to have a glass transition temperature in the same
range as that of the lignin.
WO 95/34604 ~ 97
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The core which comprise6 of from about 35'~ to
about 8596 lignin and 65~ to 15~ master batch polymer can
be extruded at a temperature of from about 115C to about
1455C to form a polymer sheath having a similar
composition as the final product It is believed that
extrusion at the foregoing temperature will result in no
damage to the lignin. Extrusion of the sheath generally
requires a temperature of frora about 170 to about 230OC.
As a target, the overall composition of the coextruded
compound is preferably equivalent to the composition of
the f; n; ChP~ product . The thickness of the sheath can be
adjusted ~ r~;ng to the diameter of the core which
corresponds to the diameter of the central f; 1. t such
that the level of lignin in the final coextruded product
is of from about 0.59~ to about 40~. In a preferred
, for a core diameter of from about 1 mm to
about 2 mm, the sheath ~h;-knP~s is of from about 4 mm to
about 5 mm such that every individual pellet of compound
comprises from about 49,~ to about 25~ of lignin.
An advantage of using coextrusion at the
compounding temperature of polyethylenes and
polypropylenes is that the problem associated with the
thermal ~ ~ Eition and ~Y;~l~t;r~n of the biopolymer is
alleviated. In this particular instance, the c~L~uded
compound upon extrusion, takes on the appearance of
pellets which are heterogeneous under the microscope but
still are more-homogeneous overall by contrast to the
appearance of pellets which result from the mechanical
mixing of two ~ifferent pellet compositions.
W0 95l34604 . ~~ 5. '~97
21~2111
--11--
The master batch of this invention can be
processed by extrusion, blowing, injection or other
processes k-nown in the art. The rn~h;nPry generally used
requires adaptation to the processes of this invention to
meet the shorter residence times which are required at
critical temperatures such as for example the oxidation
temperature. It is also believed that the processes of the
invention can operate at a lower temperature mainly
because of the additional heat protection from the sheath
to the lignin-rich core which is easier to melt and the
viscosity of which is not as sensitive to the t~ Lur e
as the PE or PP.
In certain specific applications of this
invention, organosolv lignin powder with a median particle
size of from about 0.1 micron to about 100 microns and in
a quantity of from about 0 . 5% to about 40% can be mixed
with polyethylene or more generally an ethylene copolymer
to manufacture homogeneoug films having a th; ~knPn5 of
from about 5 microns to about 100 microns. The
polyethylene blends can be prepared by direct mixing or by
using a master batch preparation. It has been ,bse- ved
that the resulting films can degrade when iron stearate or
any other photoactive and/or ~ 1; ?; n~ additives such as
cerium salt is added in a range ~r~n~l~nt on the target
film shelf life and the conditions under which the film
will be used. A preferred range is of from about 0.1% to
about 0 . 5% of salt based on total weight of polymer blend.
The plastic films thus obtained can be used for many
agricultural applications, as well as for the manufacture
Wo 95/34604 1 ~ 97
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of plastic bags for refuse, shopping baskets, etc. In
agricultural ~,nrl;~ t;nn~, in which the stiffness of the
film is essential, the lignin nnnt:: ;nin~ polyethylene film
of the present invention appears particularly interesting
to use since the degradation of the film over time is
total, both for the surfaces which are outside the ground
and for those which are buried inside the ground.
~urthermore, in the agricultural applications field, the
adsorption and absorption capacities of lignin, of
essential oils, insecticides and the like, will permit
then a use of lignin as an additive for the new
fungicidal, rat-killing or other properties.
Likewise, the adsorption properties of lignin
can be utilized so that the lignin can be incorporated
into the photoactive products prior to its mixture with
the copolymers, which has the advantage of increasing the
homogeneity and the degradability of the film. On the
other hand, this lignin cnnt~;n;ng plastic film can be
coextruded, and can therefore be a part of a composite
film.
It should further be noted that the initial
mechanical properties of the lignin cnnt~;n;ng degradable
film of the present invention are comparable to those of a
f ilm which does not contain any lignin .
WO 95134604 2 1 9 2 1 1 1 ~ ' T ~97
--13--
Generally and highly dependant on the process of
preparation, the lignin thermally behave5 by partially
r~n~l ~nc; ng with apparent fusion and without oxidizing in a
temperature range of from about 125C to about 200OC and
S on the other hand by oxidizing without rr~n~n~t;nn at
about 160C. The properties of the lignin are material to
the processes of this invention. When the lignin
condenses, it is believed that it is capable of g~nPr~t;nr,
water to approximately from about 196 to about 6~ of its
weight . Therefore, special attf~nt i ~)n must be given to
eliminating water produced during the manuf acture of the
thermoplastic polymeric material.
The lignin and polymer can be mixed in an
extruder which can be either a single or double screw. The
mixing is preferably performed in a vented ~LLLUd~L such
that any water vapor formed from the lignin is .~l ;m;n~t~
The extrusion conditions are dependent on the scale of the
process .
The rotation speed of the screw is an important
paL t~r and is a function of the materials introduced
upstream .
The temperature prof ile is also an important
element o~ the success of a good mix since the lignin must
be protected from oxidation and thermal degradation. This
can be accomplished by adding the lignin to the already
molten polymer or by using the master batch described
herein. Upon mixing with the lignin, the lignin behaves as
WO 95/34604 ~ 9~
2192~
--14--
a thermal ;~nt; n~; ~nt which results in an increase in the
oxidation temperature of the polymer. An increase in the
oxidation temperature of the mixture enables the recycling
of such material thus permitting it to be melted again for
reuse without degradation In the case where the material
can no longer be recycled and it may prove necessary to
effectively incinerate the material, addition of the
lignin is beneficial as the heating value of the lignin is
equivalent to that of the polymer used, thus allowing its
destruction by incineration.
For OEample, when the polymer used is pure
polyethylene, its oxidation temperature is about from
150C to about 160C. By contrast with about 10% lignin,
the oxidation temperature is from about 185C to about
195C and with about 25~ lignin, the n~ t;nn temperature
is from about 195C to about Z05C. In another example,
when the polymer used is polypropylene, the oxidation
temperature is from about 210C to about 220OC. By
contrast with about 10~ lignin, the oxidation temperature
i5 from about 255C to about 265C.
The tl~ ctic polymeric material of this
invention can be used in appl;n~tjnn~ known in the art for
example in extrusion/blowing applications, calendering,
injection molding to form films, plates, sheetG, tubes,
bottle caps, wrapping paper, car parts and the like.
W0 95/34604 2 1 9 2 ~ 97
In order to improve the machining of the
thermoplastic polymeric materials of this invention,
plasticizers such as styrene butadiene rubber, zinc
stearate, soybean oil to name a few can be added during
5 fabrication.
Generally as thermoplastic polymeric materials
cannot be perfumed, the invention provides for the
addition of perfume material because of the presence of
lignin or any other biopolymer which can absorb such
scent additives. In one : ' r)rii ~nt of this invention,
lignin can be mixed hot or cold either alone or in
conjunction with the thermoplastic polymeric r~t~ri:~l, In
this embodiment, the lignin can be treated by maceration
in 601vents ~ nt~;nin~ essential oils before it is blended
with the polymeric materials. In another embodiment, a
mixture of scents such as for example terpenes and
citronella can be directly injected in one o~ the sections
of the extruder during the m-nllf~rturing of the mixture.
It is to be noted that lln~rt~-il y for polymers
such as polyethylene, the addition of a biopolymer such as
lignin to a polymeric ---t~r;;~l can lead to an i~ ruv~ t
in the material ~ s resilience to ultraviolet radiation.
This is ~lnPYE~ t~l as one does not add an additive which
would enable the resistance to photodegradation but rather
the lignin plays a role in stabilizing the thermoplastic
WO 9~134604 r~ 97
2192111 ~
-16 -
polymeric material to degradation by ultraviolet radiation
as shown in Table 1. It is also to be noted that without
the lignin, an increase in ~he length of exposure to
ultraviolet radiation causes an important fragmentation of
the polymer and a sudden and sign; f i ~-~n~ variation in the
molecular weight of the polymer.
Table l
Molecular Weiqht
Length of Exposure To Polyethylene + 10%
10 I~V ~adiation (hours) Polvethvlene Liqnin
o 320,000 300,000
240,000 242,000
200 35, 000 120, 000
In a preferred ~mh~ of this invention, PVC
can be blended on a weight basis with from about 0 . 5 to
about 40% organosolv lignin ~ith a specific gravity of
about 1. 27 and a median particle size of from about 0 .1
micron to about 100 microns. The final PVC/lignin blends
have stronger mechanical properties and can degrade under
the effect of liyht. The PVC blends can be used in
medical, food, fashion and home applications.
WO 95/34604 2 1 9 2 ~ l/L '~97
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The following sets forth one particular
embodiment for the blending of PVC with organosolv lignin.
The PVC used is a commercial unplasticized resin (Geon
85862 from BF Goodrich Technical Center, Avon Lake, Ohio,
USA) as a suspension polymer of high molecular weight (k =
67) and has the following formulation: PVC resin, 100 phr;
stabilizer, 2 phr; processing aid, 1. 5 phr; impact
modifier, 6 phr; lubricants, 3.75 phr; Ti02, variable from
0 to 10 phr. With 10 phr Tio2, the PVC resin has a
specific gravity of about 1.48.
PVC blends were prepared with the composition
set forth in Table 2.
Table 2
Blend # TiO2 (~) Orqanosolv Liqnin (96)
1 9.09
2 6.81 2.27
3 g . 54 4 . 54
4 2 . 27 6 . 82
0 0
6 o 4.54
7 0 6.82
8 o 9.09
9 0 13.63
o 18 . 18
Wo 9s/34604 r~ 97
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The. blends were prepared by melt compounding in
a Haake Rheomix 600 eriuipped with roller blades at a
temperature of ~about 195C. The time of mixing was about 8
minutes at a speed of roller blades of about 65 rpm. PVC
was added first and the lignin second after about 30
seconds. Several batches were prepared or each
formulation and after melt mixing the obtained blends were
ground to a particle size of from about 3 `to about 5 mm.
Sheets with a thirknpsq of about 2 mm were molded by
compression at about 195C. After cooli~g with air and
under pressure, the sheets were cut with a cutting die in
shoulder shaped specimens for -hAn;cAl testing.
The --~hAnirAl properties, tensile strength and
elongation at break were measured before and after 5 days
and 20 days of art;f;r;;~l weathering and were correlated
with the properties of PVC controls. They were measured
in accordance with ASTM D 638 using an Instron universal
testing machine.
The weathering of the samples was carried out
using eriuipment known in the art such as a Q-Panel QW. In
this tester rain and dew are ~; 1 AtP~i by a rnn~onR-Ation
system and it rnntA;n~ a series of W-A la~ps with a peak
~m; RR; nn at 343 nm and a gpectral power distribution of
from 295 to about 400 nm. A3.1 the qrPr; q were
subjected to several cycles of 4 hours each of W exposure
at an eriui,librium temperature of about 50C alternating
with rnn~ nq~tion exposure at an eriuilibrium temperature
of ahout 40C The number of days of accelerated
weathering was 5 and 20.
W095/34604 ~1~ 211~ 97
-19-
Table 3 shows the influence of lignin on the
fusion characteristics the blends. The processability or
the fusion characteristics of PVC blends is generally
influenced by the type of resin and additives present. A
change in formulation Pcre-r; Al l y in the case of rigid PVC
composition can affect the fusion characteristics of PVC
blends and conseguently their processability. Improper
prorP~s~hil ;ty can have a negative effect on the
mechanical properties of PVC and its weatherability. It
has been found that the fusion characteristics of blends
of PVC with lignin f~1L 1l CtP~1 with or without TiO2 present
almost the same characteristics as PVC controls. One may
conclude that the fusion characteristics of PVC-lignin
blends in comparison with PVC controls are very close and
the presence of lignin does not have a negative effect on
the processability of PVC-lignin blends. The specime~s of
PVC lignin blends with Tio2 were colored from beige to tan
and PVC lignin blends without Tio2 were dark brown.
Table 3
Blend Average Average Torgue Value Average Te~ll~eL.~L~Le
Type Fusion of the melt ( C)
Time
( S ) Max . At the end At max At the end
(fusion) of 3 min. torgue of 8 min.
75 2500 1575 184 205
2 80 2530 1600 180 204
3 85 2570 1600 183 204
4 88 2425 1475 182 204
5 165 1960 1430 182 204
6 100 2280 1430 186 204
7 105 2350 1420 189 203
8 78 2370 1400 181 202
Wo 95/34604 . ~I/~_ 5 ~~97
2~92~
--20--
Table 4 shows the strain-stress data for PVC
controls and PVC-lignin blends before and after 5 and 20
days. The lack of correlation between the values of the
tensile stress-strain data predicted by the theoretical
model elaborated by Nielsen (J. Appl. Polym. Sci., Vol.
lO, 97-103 (1966) ) particularly in the case of perfect
adhesion between filler (in this case lignin) and polymer
(in this case PVC) and the experimental values shown in
Table 4 suggest a certain degree of interaction between
the two polymers in the blend. Moreover, up to a certain
level of about 6.81~ lignin acts as a reinforcing agent
without having a negative impact on the elongation. As can
be seen afer weathering, all the blends show a higher
tensile strength value than PVC controls, and the
increased values can be correlated with lignin loading and
w.-~th~ri n~ period. The /~l ~ n~at; on at break decreasing can
be also correlated with weathering period and lignin
loading. It can also be seen that after 20 days weathering
period, all the blends regardless of their TiO2 level show
a high degree of embrittlement and an increase in tensile
strength with an almost lack in ~ n~t; ~n . It is believed
that the effect observed can be due to crr~l ;nk;n~.
WO 9~134604 2 1 9 2 ~ 1 1 P~ 97
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Table 4
Blend Tensile Strencrth Elonqation at Break
~YeQ . (MPA) (~)
Initial ~ Z0 Davs Initial ~aYE 20 Days
5 5 42.30 48.36 50.52 280 289 47
40.15 45.76 49.73 332 292 269
2 43.85 48.30 49.86 281 193 61
3 44.14 49.40 50.58 326 110 45
4 47.05 50.41 51.60 312 91 30
10 8 48.66 50.26 51.67 182 51 29
In addition, after the weathering period the PVC
blends without Tio2 and the PVC blends comprising lignin
are characterized by a change in color observed only on
the exposed side to W light. In the case of PVC blends
without TiO2, the color changed from white-grey to reddish
yellow and in the case of the PVC blends comprising lignin
the color changed to lighter tones. In the case of the PVC
blends comprising 9.09~6 Tio2, the change in color after
weathering is barely perceptible which is believed to be
2~ ~ue to the effe~t of Ti~ on the weathering of PVC.
Wo 95/34604
2192~
-22--
It i8 believed that the embrittlement and color
change due to ar~ i f; ~; ~ l w~ h,~r; ng show the
su6ceptibility of both interacting polymers to W
radiation. It is believed that the lignin photodegrade as
a result of the formation of free radicals, mainly phenoxy
radicals .
The PVC blends of this invention can be
formulated to --achieve good weatherability by bl~n~in~
synergistic leyels of Tio2 and lignin.
The invention and many of its attendant
advantages will be understood from the foregoing
description, and it will be apparent that various
modif ications and changes can be made without departing
from the spirit and 6cope of the invention or sacrificing
all of its material advantages, the specific materials,
procedures and example hereinbefore described being mereIy
pref erred: ' _ ' ; R ,
For example, by blending different kinds of PVC
~_ ~1q with lignin, other types of blends can be
formulated which would have the advantage of a lower
proc~RR;n~ temperature and milder wea~ r~h;lity
conditions. Suitable ~V absorbers and/or light-thermal
stabilizer gystems can also be included in the
formulations in order to achieve suitable mechanical
properties before weathering and suitable shades o colors
in th~ e "~l blend.
Wo9S134604 Y~
~192~
--23--
In another example, the lignin and Tio2 can be
formulated together to further optimize the photochemical
reaction of the lignin and TiO2 thus af f ecting the f inal
photodegrada3:)ility of the formulation.
