Note: Descriptions are shown in the official language in which they were submitted.
WO90/11978 pcT~GB9o/oo47~
2~5~
--1--
CELLULOSIC PRODUCT, PRO OESS FOR T~E P~ODUCTION THE~EOF
AND USES THEREOF
This invention relates to a cellulosic product,
process-for the productlon thereof and uses thereof.
~he invention has particular application to the
processing of waste from paper m~lls.
In the Unlted Kingdom alone, over 500,000 tonnes
of waste are produced annually from paper mills. The
wast2 is approximately 70% water an~ 30~ dry matter by
weight; the latter is made up of approximately equal
proportions of clay (from the mlneral filler u~ed in
paper ~aking) and cellulose fi~res.
Although large quantities of this waste have been
generated for many years, a satlsfactory means of
utllising the material has not hitherto been available.
Paper makers c~rrently bear the cost of disposin~ of
the material.
8P-B-0 039 522 discloses a process for ths
manufact~re of l~quid and shock absorbing mater~al from
a suspens$on consisting wholly or substantial~y of
cellulose fibres. The suspension iq waste from a
manufactur~ng process in which fibres consisting wholly
or su~stan~ially of cellulose material are processed by
a wet method. The dry matter content of the waste is
required to contain 60-80% by weight of cellulose
fibres, from 20-40% by welght of inorganic filler and
from 0-10% of an adm~xture which is incorporated to
modlfy the properties of the end product (pellets).
The proce3s involves dewater~ng the initial suspen~ion
to a water content in the rang~ of 40-80% by welght and
then pelletlsing th~ 8emi-dry masS by squeezing it
through one or more narrow apertures. The resultant
pellets undergo a drying process. The pelletising and
drying conditions are ad~usted so that the end product
has a bulk density of 150-400 kg/m3 and a water content
of 0.5-l0~ by weight. The initial dewatering step is
WO ~/11978 PCT/GBgO/ ~ 75
20~0~
--2--
preferably such as to give a semi-dry mass containing
55-65% by weight water.
The need to use a starting material consisting
substantially of cellulose fibres limits the
applicability of the process disclosed in
EP-B-0 039 522 in that the bulk of the waste material
produced from paper making is unsuitable by virtue of
its high clay (filler) content.
It is an ob~ect of this invention to find a use
for waste material as such produced from paper making.
According to one aspect of this invention, there
is prov~ded a material in block or sheet form or ln
free-flowing particulate form which is a dewatered or
dried cellulosic pulp material having a water content
lS in the range of up to 20% by weight and whose dry
matter content comprises up to SS% by weight of
cellulosic fibres and not less than 45% by weight of
- inorganic filler particles.
In a second aspect, this inventton provides a
pr~cess for the production of a material accord~ng to
the first aspect of this invention, which process
comprises dewatering an aqueous slurry or sludge
~ containing cellulose fibres and inorganic filler, the
-~ resulting product having a dry matter content which
25 ~ comprises up to 55% by weight of cellulosic fibres and
not less than 45% by weight of inorg~n~c filler
particles and drying the resulting product to a
~- residual water content of up to 20% by weight, which
dried product is recovered in block, sheet or free-
" ~
flowing particulate form.
When the drled product i8 to bo recovered in
particulate form, a pelletising Qtep may be caried out
before or even after the drying step. Alternative~y a
dry product in the form of a sheet or block may be
comminuted to form a free-flowing meal. A dried
product containing above 10% by weight water content is
,:
WO ~/11978 ~ /~ 75
typically grey in colour and has the texture of cotton
wool. Hence it may be termed ~flock"~ 5uch dried
product preferably has a moisture content in the range
from lO to 15~ by weight. A product with such moisture
content, even if only in sheet or block form can be
used, with the minimum of breaking up, as an extender,
for example in horticultural products, typically in
peat-based products.
For many uses, however, the dried product 18 -
pelletised or otherwise comminuted, as will be
described hereinafter.
The dewatering step is advantageously carried out
on a sludge containing cellulose and inorganic filler
usin~ a filter press, preferably a screw press. Such
sludge is generally to be obtained by flocculation of
the slurry obtained in paper production. The final
water content of the mass resulting from the dewatering
stage is preferably 45-50% by weight. We have found
that the "Perrin~ Pusher Screw Press manufactured by
Wlll~am R. Perrin, Inc., 432 Monarch Avenue, AJax,
Ontario, Canada LlS 2G7 works well in the process of
this invention.
Unlike the process disclosed in EP-B-O 039 522,
the present invention may have a drying step preceding
a comminuting step. When drying precedes comminuting
or in the more specific case pelletising, the
surprising result i8 obtained that starting materials
containing higher proportions of mineral filler are
amenable to processingl and give useful end products.
~hs aforemQntioned drying step carrled out after
dewatQri~g is preferably a flash drying step.
Advantageously, the drylng step is carried out in an
apparatus which simultaneously pulverlses and dries
. further the dewatered feed mass of flock material.
Apparatus suitable for this purpose is manufactured by
Atritor Lim~ted, P.O. 80x lOl, Coventry CV6 5RD,
WO90/~1978 PCT/GB90/ ~ 75
2 ~ 3
-4-
England. The process of this invention is not limited
however to the use of this particular apparatus or to
any specific means for subdividing the flock.
Alternatively, when lower residual moisture
contents are required, in particular in the range of
0.25 to 1% by weight for reasons which will become
apparent hereinafter, drying, with or without use of an
intermediate flash drying step, is advantageously
carrled out on a vibrating fluidizing bed or on a
rotary louvered dryer.
After the dewatering step, selected additlves may
be incorporated into the semi-dry mass prior to lts
entry into the drying phase. Typical additives (which
will be selected according to the intended end use of
the final product) are colorants, fertilisers,
odourants and absorbent.
When pelletising as such is carried out in the
process of the present invention, it is preferably
carried out using an animal feed pelleting mill or an
equlvalent mill, so as to produce pellets which, if
desired, may then be compressed. The product obtained
ln this way is useful as cat litter or as hygenic
bedding for the broiler industry.
Suitably divided very dry material (generally 0.25
to 1% by weight water content) has been found to have
additional important uses. By for example
incorporating a resin into the material fed to the
drying stage, a final product can be obtalned which is
suitabl~ for shaping. iThis resin may be biodegradable
and may be starch derived. In any Ca8Q it will
generally be pre8en:t only in minor ~mount. A product
can thus be obtained which is suitable for example for
shaping lnto plant pots which because of thelr
constitution can be set in earth as such with a plant
therein, there is no need to remove the pot and discard
it when planting.
wo9o/lls78 PCT/GB90/ ~ 75
-5- 2~ 0~ 1
Thus, according to a third aspect of the
invention, there is pro~ided a moulding composition
comprising an intimate mixture comprising (a) dried or
dewatered cellulosic pulp having a dry matter aontent
of up to 60% by weight cellulose fibres and at least
40% by weight inorganic filler and containing little or
no water, and (b) a binder, the binder constituting at
least 2% by weight of the composltlon.
The binder ls preferably a synthetlc resin. For
many products, it will be sufficient to use scrap
polymer as binder. If the proportlon of pulp residue
present in the matertal with which the binder ls
blended is high (50% or more by weight) the polymer
should be in finely divided form. The binder is
~5 advantageously present in an amount of at least 5% by
weight of the composit~on. For many applications, a
binder content in the range from 10-60% by weight will
be acceptable. Preferred binder contents are in the
range 10-30% by weight; moulding compositions of the
invention having a binder content ln this range are
exc~ptional in that they are suitable for in~ect~on
~oulding, despite the very high filler content.
Both~thermoplastic and thermosetting resins may be
u~ed as synthetic resin binder.
- 2S The presently preferred thermoplastic resin binder
materials are for example low density polyethylene
(LDPE), polypropylene (PP), ethylene-propylene
copolymer3, acrylonitrlle-butadiene-styrene copolymers,
poly~mldes, especiallyinylon, ln particular nylon-6,
and thermoplastlc rubbers. LDPE and PP are preferred
bscause of meltlng rang .
Thermosetting reslns whlch may be employed include
urea/formaldehyde, phenolic, polyurethane,
polyisocyanurate, polyurea, polyester, epoxy and
bismaleimlde resins as well as polyamide caæting
systems, e.g. Nyrim ~Registered Trade Mark). The
~WO90/llg78 PCT/GBgO/~7s
-6- 2 Q ~ f~
resin forming material in general may be fixed with the
cellulose-containing material either before drying or
after drying thereof to a suitable state for moulding.
The character of the thermosetting system to be
S employed will determine the stage at which mixing wi~h
cellulose-containing material which is to be dried, is
being dried or has been dried is to occur and the
material to be then mixed with such material. Some
systems will generally require a peroxide or other
catalyst and the character of the system will depend
upan how it is constituted. Thus, when unsaturated
polymers or cross-linkable monomers aré to be cured in
situ using a peroxide or other catalyst, for example
when using unsaturated polyesters, acrylics and allyl
- 15 resirs, it is necessary to consider two-pack systems
with catalyst only being introduced prior to the
moulding stage. Where catalysts are only activated at
high temperatures, for example above 150C, a "two-
pack" approach is not required. Such situation applies
to such general thermosetting ma~eriAls as phenolic
resins, urea-formaldehyde resins, melamine-formaldehyde
resins, polyester sheet moulding compounds (SMC) and
d~ugh mQulding compounds (DMC).
The mixing of additives into a composition
containing large guantities of pulp residue will
generally require a dough mixer or planetary mixer
owing to the viscosities involved. The high
viscositles resulting from the presence of large
quantities of~pulp r~sidue (i.e.~ more than 30%) in the
composltion~ will al80 prevent the proces81ng of these
composltlons by tradltional casting techniques. Should
relatively high pressures be necessary to ensure
adequate filling of moulds, compression moulding is
therefore a suitable technique to adopt.
Alternatively, in~ection moulding may be feasible,
although its use will be limited to lower melting
~0 ~/11978 PCT~GB~/~7~
2 ~
--7--
polymer-containing moulding compositions as too high a
temperature will induce degradation of the cellulose.
A preferred moulding eomposition aeeording to a
fourth aspect of the invention is an in~eetion moulding
composition whieh eomprises an intimate mixture derived
from (a) dried or dewatered pulp obtained as a waste
produet from a paper making proeess, the pulp
eontaining, as dry material, up to 60% by wel~ht
eellulose fibres and not less than 40% by weight
inorganie filler and eontaining llttle or no water; and
(b) a thermoplastie resin, e.g. low density
polyethylene, the resln eonstltutlng at least 5% by
weight of the eomposition.
Compression mouldlng of eompositlons embodylng the
invention works satisfaetorily over a wide range of
binder eontents in the eomposition. It is possible to
form artieles from preferred eompositions in aeeordanee
with the invention by in~eetion moulding even at
relatively low blnd r eontents. In~eetlon mouldlng of
m~t rlals eonvention~liy requires a eonslderable
proportion of binder to he present in order for the
in~eetion moulding to work satlsfaetorlly. We have
; found that sueeessful in~eetion moulding runs ean be
aehieved with eompositions of this inventlon wlth a
.~ 25 binder eontent (speeifieally, but not neeessarily only
wlth low d~ensity polyathylene) as low as 5~ by weight
of this eomposition and gen~rally as low as 10~ by
weight.
Ifideslred,~one or more addltlves may be
ineorporated into a mouldlng eomposltlon ln aeeordanee
wit~ th$s lnvention, typie~lly in relatively small
-~ amounts, e.g. up to about lO~ by welght of the
eomposltion. Sueh additives inelude fire retardants,
eolorants, water repellants and other eonvention~l
ingredients. Moulding eompositions embodying thls
inventlon llke the aforementioned Nfloek" and similar
','~
,~
~WO90/11978 PCT/G890~7s
2 ~ ~ 5 i~ 3
material are hygroscopic and need to be bagged as soon
as possible after their production. However, moulded
pr~ducts produced thererom, as a result of the effect
of the binder, are less hygroscopic.
For use in forming a moulding composition of this
invention, the waste from paper making is preferably
dried directly to a very low water content after being
sub~ected to prelimlnary dewatering. ~hereafter the
dried pulp can be mixed intimately with a binder,
typ~cally a resin, ~o form the moulding compos~tion of
this in~ention. Mlxing with binder is preferably
carried out using a Z-blade mixer or a planetary mixer
and/or by feeding the starting ma~erials for produc~ng
the moulding composition through an extruder. More
homogenous mixing can be achieved if an initial Z-blade
mixing process is followed by one or two passes through
an extruder, e.g. a Betol extruder. It is convenlent
for the dried cellulosic pulp to be in the form of
pellets or granules as it is supplied to the mixing
process. Granulation of air dried pulp may ~e carsied
out ln a Christy Norris Spruemaster grarlulator which
can be fitted with differerlt size sieves to control
crumb size. If mixing wlth binder takes place at an
early stage in the drying. cellulose con~a~ning waste
whose water content is still as high as 40% by weight
may be contemplated. Such cellulose-contain~ng
mater~al will however have a bulk which is
disadvantageous; mixing o~ the flock with the binder is
less qonveni~n~ than using dried granules~or p~llets.
Moreover the presence of substantial amount~ of water
produces vapour problems in an extruder used for mixing
and in subsequent moulding equipment.
When the compounding of pulp residue with ~inder
comprises an extrusion techni~ue, compounding can be
successfully carried out in a conventional twin-screw
compounding extruder. For low density polyethylene,
-~090/11978 PCT/GB90/00475
-9- 2~ 6a~
barrel temperatures in the region of 150-160C and die
temperatures around 170C can be used. The extrudate
itself can be pelletised. To obtain a completely
uniform product, overall intensive mixing is required
S and this may be achieved by (a) passing the extrudate
through the extruder a second time or (b) fitting a
cavlty transfer mixer between the barrel and the die or
(c) using a specialised c~mpoundlng machine, e.g. Bus
Ko-Kneader.
Polymers which have high melt temperatures may
cause dlfficulties as the cellulose flbres present can
degrade. For example, nylon-6 having a melting point
of about 215C can only be blended with cellulose-
containing material provided that the residence time of
the mix in the barrel of an extruder is kept as short
as possible. No problem in this respect is achieved
with polypropylene which has a melting point of about
170C
Pulp residue contalning in~ection moulding
cc3pos$tlons ~ould e~sily. The pulp residue appears to
h~ve a lubricating effect. How~ever, when high filler
~ and fibre contents are employed (greater than 50% by
-~- w d ght of pulp residue), difficulties may be
- encountered in injectlon mouldlng of thin sections.
- 25 Moulding compositions containing pulp residue
~ mould more easily than compositions containing similar
-; l~vels of re conventional fillers. In some
e bcdi ents of the invention, one or more conventional
flllers m~y b~,incorporated into a mould~ng composition
accord~ng to thi8 invention. Such fillers ~nclude
powders, gla8s, wood, fi~re, talc and whitlng; the
;~ inclusion of these additlonal fillers may be
deleterlous lf the composltion ls to be in~ected
moulded. Higher filler loadings are possible with pulp
residue th~n conventional fillers such as glass fibre,
whiting, china clay etc. used as sole source of filler.
--WO ~/11978 PCT/GB90/ ~ 75
-lo- 2~
Although the use of cellulosic pulp in the
practice of this invention is mainly described herein
with reference to utilization of paper mill waste,
pulped waste paper can also be as an alternative or in
addition thereto.
The following examples illustrate the invention.
In the examples, reference will be made to the
accompanying drawing. The term n flock~ is used in the
examples to denote feedstock containing cellulose and
filler wlth wh~ch binder is mixed.
EXAMPLE 1
Waste from a paper mill is supplied at l to a
screw press 2. The waste contained dry matter
consisting, by weight of 50% inorganic filler (clay)
lS and 50% cellulose fibres. The solid matter content of
the waste was approximately 30% by weight. The output
of the screw press (at 3) had a moisture content of
about 45% by weight. This partially dewatered material
was-supplied to a flash dryer 4, which was an ~Atritor
dryer-pulverlser~ manufactured by Atrltor Llmited of
Coventry, England. The output from dryer 4 was a grey
fluffy materlal wlth a low water content. In one
embodiment of the ~nvention, this material may be used
~ directly as a drying or absorbing agent or as an
-~ 25 extender, e.g. for horticultural composts.
In another e bod1ment, the output at 5 from the
dryer 4 i~ fed to the input 6 of the pelletising press.
~- This may be a conventional pelletising press of the
type used for pelletlsihg animal feed. The pelletiqed
product pa8ses (at 8) to a two-stage packing plant 9,
,~ 10.
If desired, additives may be incorporated into the
feed stock at the input to the flash dryer 4.
The final, pellet$sed product may be used as cat
litter, or for other applications where good liquid
absorbing and/or shock-absorbing products are required.
WO 90/lV78 PCI'/GB90/00475
The product m~y also be used in the production of
moulding compositions when its moisture content is
reduced fur~her.
EXAMPLE 2
The procedure of Example 1 was modified in that
using a "Perrin" Pusher Screw Press, the starting
sludge was ~nitially dewatered to around 50~ dry
weight. The output from the screw press was fed to a
"Atritor" dryer-pulveriser which reduced the water
content of the material to approx~mately 30%. The
resultant grey flock product was then dried to
substantially complete dryness in an oven at 110C. At
the end of this process, the dry cellulosic flock
contained only 0.6% by weight of water. The dry flock
was then mixed in a Kenwood planetary mixer with a
commercially available }ow d-ensity polyethylene (LD110
manufactured by Plascoat Systems) for three minutes.
In a first run, 124 parts by weight of the dry flock
were mixed with 16 parts by weight low density
polyethylene, this corresponding to 11.4% by weight
resin in the composition (dry weight). The mixture
obtained in the planetary mixer was then passed twice
through a Betol extruder. The resultant intimate
mixture was then used to form in~ection moulded pots
us~ng a DAn~els Press operating at 180C. Thè
~- resulting product was easily demouldable and had a
smooth uniform glossy dark grey appearance.
A second sample of the dry flock was treated in
the same way asldescribed abuve, except that the
mlxture supplled to the planetary mixer consisted of
138 par~s by we~ght dry flock and 40 parts by weight
low density polyethylene (LDI10). This corresponds to
22.5% by weight resin in the composition ~dry weight).
As with the previous sample, injection moulding
produced a satisfactory product with no processing
difficulties.
. ~ WO90/11978 PCT/GB90/0047~
2~?~s9~0~
-12-
EXAMPLE 3
Following the procedure of Example 2, further
injection moulded products containing pulp residue and
low density polyethylene were produced, the contents of
flock (dry weight) in the moulding produced amounting
to 50, 65 and 85% by weight. For comparison, a
moulding was produced from the low den ity polyethylene
alone.
The properties of the products thus obtained were
then invest~gated. Firstly strength and modulus values
were determined and yielded the following values:-
TABLE l
.
Property % Flock in Compound
lS
0 50 65 85
.
Flexural Strength No failure 17.116.4 10.8
Mpa
Flexural M~dulus 0.24-0.33 1.31.69 2.5
GPa
.
Tensile Strength 8.3-31.4 4.978.84
5.97
MPa
.. . . .
As with the!flexural and tensile properties, the
intensity o mixing and the moulding conditions will
considerably in~luence the impact properties. In
particular, the ~mpact strength w~ll be subJect to
greater variability if mixing has not been int~nsive.
All the aforementioned samples were mixed under the
same conditions and they were subjected to impact test
measurement which yielded the following results:-
~ -' 90/11978 P~/GB90/00475
,_
-13- 2~6~
TABLE 2
% Pulp Residue 0% 50% 65% 85%
~;
Impact KJ/m2 No break 4.4 S.4 6.5
Izod Test
The moulded artlcles werQ all sub~ected to working
following woodworking techniques, for example,
drilling, nalling, screwing and sawing, and no problems
were encountered when the pulp residue constituted 50-
8S% by weight of the moulding.
The incorporation of flock enhances the fire
resistance of polyethylene moulded bodies which will
not;melt, drip or lose int-grity in the same manner as
unmodi~fied~polyethyl~ne when pulp residues are high,
e.g. 85-80~. ~owever the compogitions still burn and
are~not~self extinguis=hlng.
; 20 Fu~ther tests were carried out on the
d ~reaeneLoned mouldings, which~ being relatively
por~cus, can absorb signif~cant amounts of water or
solvents.~MouIdings containing high levels of pulp
residue are most affected as shown by the following
. ~
~ 25 results:-
,; ~,.,
"~
" ~
:~:
,
,,
. ,,
' :~
~,
''''":
';
,~
~'0 ~1197B PCTlGB90/ ~ 7~
.
-14- 2 ?~ g
TABLE 3
% Pulp Residue ~ by wt. of water absorbed by immersion
in moulding 24 hr. 1 week 1 month 2 months
_ _ _ _
0 <0.01 NA NA NA
1.1 3.0 6.3 8.4
1.5 4.2 8.9 10.2
2.6 8.5 12.1 12.3
NA - Not available
If the moulding compositions are not uniorm1y
compounded, this may lead to warping. Significant
dimensional changes may occur in humid environments
owing to water uptake. Water may extract material from
the mouldings during prolonged immersion as sugges~ed
by the following results:-
TABLE 4
% pulp Residue 0 50 65 85
- in moulding
25 % extracted after~,~ O <.1 ~.1 1.
2 months immersion
in water
_
Comparable experiments carried out using an
orgaoic solvent (petrol) showed the extent to which it
may also be absorbed by pulp residue/polyethylene
mouldings or extracts material from such mouldings.
WO90/11978 PCTrG890/~75
-15- 2 ? ~, 9 ~5 ;~, ~
TABLE 5
% Pulp Residue % by wt. of petrol absorbed by immersion
in moulding 48 hr. 1 week 1 month 2 months
S _
6.2 7.1 7.3 7.7
5.9 6.5 6.4 7.0
3.3 3.1 3.2 3.7
. ..
TABLE 6
.
% Pulp Residue 0 50 65 85
15 in moulding
% by wt. material ~ NA 1.9 2.6 4.8
ex~tracted in
2 cntbs
20~
, ~ ~ ~ ,. . __
In each of the following examples, there was used
a~pulp rssidue from a waste paper mill which had been
d wat red~and dried to a`resldual water content of less
~hAn~1% by~w d ght, the pulp re ldue having a dry weight
compositiQn of 50% cellulose and 50% clay.
;~r_ ~ '
EXAMP~E -4
~-~ 100 gr~s of dried pulp res1due were placed in the
, ..
~ m~Y~ng!~cha b r~of~ a! ~mJll pl~netary mdxer followed by
;~ 30 47.5g of epoxy resin (Eplkote 828, Shell Chemicals).
~ The cur1ng~ugsnt, 2.5g of benzyl dimethylamine, W~8
y~ add-d over a 5 minute period and mixed in for a further
15 minute This was designated Compound A.
~5~ ' A portion of Compound A was pressed in a steel
mould at 80C to produce sheet mould$ngs approximately
~ 1.2mm X 115mm X 115mm. A pressure of approximately
,,, ,~ ~
, . " ~ ,
-
,i, ~:
WO90/11~8 PCT~GB90/ ~ 75
-16- 2~ a 0
900kg was applied to the mould and the moulding was
removed after 15 minutes. The product was a hard, rigid
sheet.
A second portion of Compound A was pressed in a
different steel mould at 80/100C for 3G minutes to
produce a sheet 2.7mm X ll5mm. A pressure of
approximatqly 900kg was applied to the mould. The
product was a hard, black, rigid sheet.
When Compound A was left overnight before use
unsatisfactory mouldings were produced owing to
moisture uptake.
EXAMPLE 5
4 grams of phthalic anhydride were dissolved in 50
gram;s of acetone and this was mixed into 45 grams pulp
residue using a small planotary mixture. Then lO grams
of an epoxy resin (Epikote 828 from Shell Chemicals)
was mixed 1 . The mixture was spread out on a tray to
-allow~most of the acetone to evaporate. This took
~approxL~ately l hour. Thi~ wa d~signated Compound B.
A~pcrtlon of Co pound B was then pressed in ll5mm X
l.2mm sheet mould for l hour at 150C. The product was
~-~ a hard r~gid black sheet.
` If Ccmpound B was left overnlght before use
unsatisfactory mouldings were produced owing to
moisture uptake.
.,.:
EXAMPLE 6
; lOOg of~;dried pulp re8idue wsre placed ln the
mixlng vessel of a 8mall planetary mixer. Then a
-~ premix of 20g linear polyether diol (Desmophen l900
from Bayer UK), O.Ol dibutyl t~n dilaurate ~nd 0.05g of
a 33% solution of triethylene diamine in polyethylene
:~.
glycol molecular weight 200 was prepared. This premix
was mixed into the pulp residue for 30 minutes. Then
27.4g of polymeric diphenylmethane diisocyanate
.,
~.
, . . .
,,~ .,~
~,-, ::
.,
WO90~11978 PCT/GB90/ ~ 75
-17- 2 0 ~ 3
(Suprasec DND from ICI) were mixed in for 20 minutes.
This was designated Compound D. The amount of
isocyanate and polyether used were such that an excess
of isocyanate was present.
A portion of Compound C was immediately pressed at
80/100C in a llSmm X llSmm X 1.2mm sheet mould. A
pressure read~ng of 2000psi (13790 kpa) was used for 20
minutes . The product was a tough rigid sheet.
Approximately 30 mlnutes after mixing~ a portion
of Compound C was pressed at 80 to 100C in a 115mm X
llSmm X 2.7mm sheet mould. A pressure reading of
2000psi (13790 kpa) was used for 100 minutes, This
product was a tough rigid sheet.
If Compound C was left overnight before use,
unsatisfactory mouldings resulted.
EXAMPLE 7
lOOg of dried pulp residue and a pre-mix of SOg
Deæmophen 1900, O.lg of a 33% solution of triethylene
diamine in polyethylene glycol of molecular weight 200
and 0.03 dibutyl tin dilaurate were mixed on a
planetary mixer before mixing in 7.8g Suprasec DND.
This was designated Compound D. A portio~ of Compound
D was compression moulded as in Examples 4 and 5.
2S The compression moulded sheets were soft and
exuded traces of unreacted polyQther d~ol. The amounts
of ~socyanate and polyether used were of stoichiometric
equivalent molar guantitles.
; i
EXAMPLE 8
lOOg of dried pulp re~idue were mixed with 34g of
a pra-mix of 68% Desmophen 1200 (a branched polyester
polyol), 0.02g dibutyl tin dilaurate and 0.08g of a 33%
' solution of triethylene diamine in polyethylene glycol
(m.w. 200). This was carried out in a planetary mixer
over a 1 hour period.
WO90/11~8 PCT/GB90/00475
-18- 2~ 3~,
Then 14g Suprasec DND were added and ~ixed in over
15 minutes. This was designated Compound E. The
products were pressed into sheets as in Example 6.
The sheets were hard, rigid and black. An
improvement had been brought about by using a more
reactive polyol with a branched structure. Also,
though equivalent amounts of polyester polyol and
isocyanate were used, the formulation contained a
higher percentage of isocyanate and was better able to
tolerate trace guantities of water.
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