Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~: 1 3~21 98 `
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This invention relates to colour concentrates.
More particularly, this invention relates to a
method of preparing organic colouring concentrates in
thermo plastic resins.
Various types of colour concentrates are known in
the prior art. Basically, colour concentrates are used
in the thermoplastic industry for providing colouring
ingredients for resins, which in turn, are used for
various types of products ranging from film , to
injection molding products or the like. Many of the
colouring additives used in the thermoplastic industry
are inorganic compounds. Typical of such compounds is ~;~
titanium dioxide, an inorganic additive, which provides ~-
a "white" colour for thermoplastic materials. Generally
speaking, inorganic colour concentrates can be produced
by various techniques without encountering problems of
dispersion of the pigment in the resin.
Organic pigments, on the other hand, pose a
different set of problems. When combined with various
20 typee of thermoplastic resins, eg. the polyethylenes, -~
the colour concentrates incorporating organic pigments
can be and are quite useful~in producing various types
of thermoplastic materials which have bright colours.
Due to the fact that the colouring agent per se is an -
25 ~ organic pigment, the prior art has been faced with
; problems in trying to produce organic pigment
concentrates~of thermoplastic compounds; generally, -~
these concentrates are only of }0 to 20 % organic
v~ pigment, (typically 15 %), in commercial products -
I available to the industry.
The~problems encountered in producing a higher
load~ing~level for~organic pigments in thermoplastic
resins (such concentrations being in the order of 40 to
60 %) deal with the fact that the organic pigment
component tends to agglomerate before or during
dispersion;into the molten carrier resin to be coloureds
the agglomerates remain as such and do not
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dispe~se so that the resulting product may have "spots"
or non-dispersed organic particles, which in the worst ~;
case renders the product useless or does not permit the
production of a satisfactory product from an appearance
point of view. As a minimum, the undispersed pigments
do not develop the full colour potential of the pigments
in the resin. -~
Again, generally speaking, it is desirable to ~ -
provide a higher loading or "super" concentrate of an
organic pigment in a thermoplastic resin carrier, in the
order of 40 to 60 %, to permit the users of the
concentrates to employ this "master batch" which could
reduce cost to the manufacturer of thermoplastic
products; making hi`gher concentrations of the "master
batches" where the organic compound is employed would
also enable higher production capacities in plants
; manufacturing the concentrates, which can then be
shipped to eg. satellite plants or directly to the users ; `~
for "let-down"; finally, it may be possible to obtain
; 20 better dispersion/non-agglomeration to provide clearer~ ;
products which are coloured with organic concentrates if
indeed non-agglomerating "master batches" could be
obtained.
In an attempt to solve the problems of
agglomeration and poor dispersion for organic colour
pigments in concentrates, while having high colour
~; pigment loadings, the prior art has had to resort to two
different types of solutions. One solution is to
provide special hydrophilic resins as carrier materials,
30 ! in combination with special processing aids and in ;this
manner, colour loading of approximately 40 % in these -~
special resins and processing aids have been obtained.
The problem with this type of solution is that due to
the special resins, and inclusion of special processing ~
35 aids, it may not always be possible to utilize this type ~-
of concentrated organic colouring mixture with different
types of thermoplastic materials which the colouring
32~ ~8
concentrate is normally intended to be used with. Thus,
not all of the thermoplastic resins would be compatible
with the special resins and special processing aids;
problemæ can occur in compatibility wherein such
compatibility may show up in the end products.
A second solution is to employ special low
molecular weight waxes as the carrier materials for the
organic pigments; this has resulted in concentrations of
around 40 % of organic pigment. Such low molecular
weight waxes, having molecular weight of less than
5,000, are normally melted in a pot or bath together
with the pigments, and the resulting products are then
pelletized to produce the "master batch". Again, since
low molecular weight waxes are employed as the carrier -~
or host material for the organic pigments, special
problems can be encountered with non-compatible ;~
thermoplastic materials in which the colouring
concentrate is intended to be added to; in `addition, low
molecular-weight materials tend to migrate to the ~
20 surface of any product and this may not be desirable in ~ -
many cases.
Conventionally, the organic pigments are normally
employed with var~ious types of processing aids, when
making "master~batches" of 10 to 20 % concentration of ~;~
25 ~ the ~organic~pigments~. These processing aids may include ~ ~-
various~types of additives,~such as zinc stearate, etc.
As-~po~Dted~out~above, as the inclusion of additives can
be mere~ly for~the purpose of permitting a colour
concentrate to be manufactured, the additives may not
jnecessarily be compatible with the use of the colour
concentrate in certain types of thermoplastics, not only
bec;ause it is not desired to have such additives in the
fina~l thermoplastlc product to which the colour
concentrate has been used, but also for certain types of ``~
products such~as those in contact with food where such
additives may~not be desirable. `
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Acco~dingly, it would be desirable if a method of
producing colour concentrates with conventional carrier
materials, e.g. normal molecular weight i.e. having a
molecular weight of at least 10,000 for polyolefins, or
polystyrenes, could be achieved for organic pigments in
which there was a high loading of the pigments. To this -~
end, in accordance with the present invention, there is
provided such a method which comprises providing a
source of hydrophobic carrier resin having a molecular - -
weight in excess of 10,000, providing a source of an
organic colouring pigment, said pigment being
substantially free of processing aids, separately
charging each of said carrier resin and said organic `
pigment to a high intensity mixer, mixing and blending
said carrier resin and said organic pigment in said high
intensity mixer for a period of time sufficient to
form a low density semi-molten substantially non-
flowable viscous mass-blend of said carrier resin and
said organic pigment, and forming said mass into a ;
colour concentrate.
In further aspects of the present invention, there
. .
is also provided a colour concentrate of an organic ;-
pigment and a hydrophobic carrier resin having a
molecular weight greater than 10,000, said pigment being ;
present in an amount of greater than 25% by weight of
~ the total composition, and being substantially uniformly
`~ dispersed in said composition, the balance of said
~composition being said carrier resin and being ;~
substantially free from agglomeration.
In addition to the above, the method of the present
inventionimay be used to prepare colour concentrates
having lower than 25% organic pigment, with conventional
carrier resins.
In greater detail of the present invention, colour ~ ~
concentrates of organic pigments having conventional ~;
carrier resins, free from conventional processing aids,
can now be prepared in an economical and easy manner. -~
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-5- 1 3321 98
Thus, one may employ any of the conventional c~rrier
resins of a hydrophobic nature, which are normally used
in the manufacture of various types of end products
ranging from film to cast or injection molded products,
and in which the organic pigment is substantially
uniformly dispersed in the carrier resin and is prPsent
in a non-agglomerating condition. Generally speaking,
the carrier resin can now be chosen to match the type of ~:
resin which the colour concentrate is adapted to be
added to. In this way, compatibility between the colour
concentrate carrier resin, and the processing resin, can
either be selected accordingly, or can be the same in :~
many cases.
Typical of the carrier resins that may be employed, ;~
15 for the more common processing resins used in industry, :
are those which are hydrophobic in nature, such as;
: polyethylene, polypropylene, copolymers of polyethylene,
~ copolymers of polypxopylene, polystyrene and the like. ~ .
.:
~:~ These resins will have a molecular weight in excess of .~
:~ 20 10,000 and their densities may vary considerably, ~::
depending on the properties desired for the carrier
resin in the colour concentrate.
Typical of the organic pigments that may be
employed with the present invention are those organic ;.. /-~
25 :pigments which provide yellow, blue, green, red or the .-
Iike colours; while there are a large variety of organic
pigments available for the purpose of colouring
thermoplastic resins, typical of such organic pigments
are~copper phthalocyanine blue, phthalocyanine blue -
alpha and beta, lithol rubine red, diarylide yellow
"AAMX" "AAA" "AAOT" "AAOAn, dianisidine orange "AAA", ; ;~
~: phthalocyanine green, and calcium lithol red, red
calcium "2B", barium "2B", strontium "2B", manganese ~-
"2B", red calcium "4B", and red lake "C".
~B
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321 98
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In carrying out the method of the present
invention, it is important that separate sources of the
organic pigmen-t, and the hydrophobic carrier resin, be
added to the high intensity blending step. Tests have
shown that should these ingredients be pre-blended,
agglomeration and poor dispersion will result, rendering
the colour concentrate of limited usefulness, if at all.
Conversely, it is most preferred according to the ;
present invention substantially simultaneously to add
each source to the high intensity mixing step - this can
be conveniently carried out by providing separate
charges of the desired amounts of organic pigment and
hydrophobic carrier resin to the high intensity mixing
step and thereafter subjecting the separate charges of -
; 15 such components together to a blending operation in the
high intensity mixer.
Having thus generally described the invention, `
reference will now be made to the accompanying examples,
illustrating preferred embodiments.
-~ 20 EXAMPLE 1
For this example, a series of formulations were
prepared both according to the invention and according
to conventional practice. The apparatus employed in the
example for blending the resin and additives is that
known as a "Gelimat", which is a high intensity mixer.
The following compositions were utilized. ~
Composition: Components % Amount ~1
;~ A) YelloW RGS
~;- Litnopone 25.0
~;; 30 , Zn Stearate 1.7
LLDPE 15.0
B) Yellow RGS 25.0 ~-~
TiO 41.7 -
i Zn ~tearate 1.7
LLDPE 31.6
`'; ~''"'.~''
I ~
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1 332 1 98
-7-
C) Yellow RGS 30.0
LLDPE 70.0
D) Yellow RGS 50.0
LLDPE 50.0
...
In the above compositions, none of the ingredients -~
were pre-blended; the term "Yellow RGS" designates a
yellow organic pigment; the term "LLDPE" designates a
linear low density polyethylene of a 12 melt index. ;~
In carrying out the method of the present
invention, as noted above, separate sources of the ~ -~
.,: -.:
~ organic pigment and the hydrophobic carrier resin are
~ . , , . . -
added to the high intensity blending step. Addition is
preferably carried out simultaneously, although one can
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practice the present invention by sequentially adding ;~-
separate sources provided that all separate sources are
added before any individual component is worked to a ~ -:
15 sufficient extent by the high intensity mixing device so i~
that it~becomes semi-molten or agglomerated. In other
words, it is possible to separately charge the organic ;~
p~igment and carrier resin individually, but both have to --
be present~in the high intensity mixing step before the
0~ dis~creet proper~ties of the components fed to the high ~ -~
intenslty mixing step are altered to any significant
extent ~j ;
In terms ~of the high intensity mixing step, a most ~`
con~venient~and suitable apparatus for carrying out the
5 ~method~of`the~près~ent invention utilizes a "Gelimat"
apparatus;~ such devlces come in varying sizes
tcapacities). The "Gelimat" apparatus is basically a
batch-type ~evice where individual batches of the '
products are blended and the~ ~ischarged. Reference may
30 be~had to co-pending;Canadian Patent Application, ~;
Serial~No. 486,540, f~iled July 9, 1985 for the pro~
cess and apparatus conditions for the use of the
., .. ; ~ ", ~ -
~ "Gelimat" type device. In
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' -8- 1 3321 '~8
the method of this invention, the charge size may vary
from small batches of eg. 2 pounds or more of
ingredient~ to 6 pounds or more; preferably the blending
is carried out in time intervals varying from 10 to
about 15 seconds, although such time intervals can be
varied as desired. The temperature at which the
products are subjected to may likewise vary; typically,
these can be from about 125 - 150C - that is the "dump"
temperature of the product after being fluxed will
10 normally be in this range, although wide variations can ~
be expected depending on the type oE organic pigment and ~-
the hydrophobic carrier resin used.
A~ter fluxing/blending according to the present
invention, the product can then be processed in one of i;
15 several different manners; for example, the product can
then be passed through an extruder and subsequently
pelletized after extrusion, or stil~ further, the
product emanating from the "Gelimat" can be ground into
; a powdèr by a conventional grinding apparatus.
One of the primary features of the present
invention is the fact that by the method disclosed
herein, the hydrophobic carrier resin can be the same
resin as that which the colour concentrate product is
intended to be used with. Thus, a typical carrier resin
25 may be an eg. linear low density polyethylene and the
resulting colour concentrate having a load factor of 30
to 50~ can then be employed as a colour concentrate for
such linear low density polyethylenes in the
conventional process. This is a significant advantage
30 since there will be inherent compatibility between the !
organic concentrate in its carrier resin with the resin
; to which the organic concentrate is intended to be used
with; whereby problems aqsociated with non-compatibility
as were encountered in the prior art can then be
avoided. Typically, the colour concentrates of the
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g .: ~
present invention will range between 25 to 50% of
organic pigment or more, depending upon the type of
organic pigment employed. When produced, the organic ~;
concentrate can be let down with compatible resins and
there after used in a diluted form or if desired, can be
used directly as produced by the present invention. In
most cases, the organic pigments can be let down after
transportation to a suitable point where such organic ;
concentrates are used, resulting in savings of ~-
transportation costs.
Accordingly, a further step in the method of the
present invention involves taking the colour concentrate ;~
obtained by the above described method, diluting the
same with a compatible resin, and subsequently adding `~
the diluted colour concen-trate as a colour additive to a
resin which is to be extruded, molded or the like.
Typically, when the colour concentrate of the present
invention is let down, it will be diluted t`o typically
between .25% to about 5% by weight of the compatible ~ ~-
resin; the compatible resin can be any resin which is
compatible with the carrier resin and most preferably,
is of the same type as the carrier resin. Thus, if the
carrier resin were a low density polyethylene, likewise
the resin in which the colour concentrate is let down
25 will be a low density polyethylene resin. Of course, ~~
various copolymers of polyethylene are substantially
compatible with such carrier resins as polyethylene and
they likewise may also be employed. -
For final use, the colouring concentrate will be ~`
employed in varying amounts depending on the degree of
colour desired but typically, these range from 1/4 of 1%
to 10%. It will be understood, however, that such
~; amounts are well known by those skilled in this art.
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Another feature of the method of the present
invention, and particularly to the products obtained
thereby, is the fact that various additives can be
eliminated which were required by prior art techniques
in order to produce high concentrations of organic
colouring components. In fact, as noted above, in
carrying out the method, the organic pigment and the
carrier resin should be free of additives in order to
not exhibit some of the detrimental side effects
associated with these additives. However, if desired,
after the product has been formed, additional additives ~-~
may be incorporated in subsequent steps.
For each composition, a colouring concentrate was
prepared by feeding each individual ingredient in a ;-~
separate container (a plastic bag) into the "Gelimat"
apparatus via a feed chute; the fluxing time in the
~ "Gelimat" for the ingredients varie~d between 12 to 14
:~ seconds for the different compositions and a batch
material was discharged from the "Gelimat" at
approximately 135C.
Each of the batches produced by the "Gelimat" was
then passed through a gear pump extruder and pelletized
to result in a product in which the individual
ingredients were formed into a blended composition.
2~5 ; Following pelletizing, each composition was then
used~as a colouring composition for a linear low density
polyethylene of a 1 melt index, in which the colouring
composition was let~down and blown into film where the
resulting film had a 0.75% organic yellow content. Each
film thus produced was studied to determine the
dispersion of the organic pigment in the colouring
conaentrate, with ratings being from Q to 5 with 0 ~;
representing very~ poor dispersion of the colouring ;
oomposition, to 5 representing very good dispersion of
such colouring compositions.
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-11- 1332198 ` ~:
The results of the dispersion testing are as -~
follows~
TABLE 1 ~;
Composition Dispersion Ratinq
A 0
B 3
C 4
D 4
Commercial Product 2
From the above results, it will be seen that ~ s`~
compositions C and D which employed the organic ``
colouring pigments together with the carrier resin, ~ J.,.'",
namely the linear low density polyethylene resin, each ` ~
10 had a very good dispersion rating of 4; a typical ~`;;`
commercial product only received a rating of 2 showing
that by using the techniques of the present invention,
vastly superior results can be obtained, and this was ~`~
achieved using compositions of between 30 to 50% organic ``
15 pigment loading. Those compositions which included `~
c~onventional additives, yet the same organic pigment, in
; amounts of only 25% received either a very poor rating
or~ at the best a~good rating~, even though they contained ; -
;a~lower amount o~ organic pigment than the compositions;
20 used in trials C and~D according to the present
invention. It is evident, therefore, that higher
loading~ with signif~icantly improved dispersion~results
càn~bè obtained~whe~n using the techniques of the present
nvention.
25 ~EXAMPLE~
Procedures similar to those of Example 1 were ~ f~
repeated, but in this case, the following compositions ~
were used. ~ ;
Compos~i;tion~ comPonents % Amount ~ ,''"~',~-!'
E) ~ ~ ~ellow RGS 50 `~-
LLDPE ~ 50 ,
F) Yellow RGS 60
` LLDPE 40
--~ 1 332 1 98
Processing conditions were similar to those of
Example l; the products obtained were let down in 1 melt ~ ~;
index linear low density polyethylene and blown into a
film, again so that the film had a .75% organic yellow
content. Table 2, following, shows the results with the
measurement ratings being based on a scale of 0 to 5 as
described above.
TABLE 2
Composition Dispersion Rating
10E)
F) l
; Again, using the techniques of the present invention, ~ -
excellent dispersion was obtained using a 50:50 organic
colouring additive; using this particular organic `~
colouring additive, at an amount of 60% compared to the
carrier resin, the dispersion ratings fell to an
unacceptable level of l for blown film. Thus, for this
particular yellow pigment, a threshold value below 60
`; of organic pigment would be applicable.
The above~procedures of Examples 1 and 2 were
20 ~repeated, using varying amounts of load levels for the
organic pigments and carrier resins and varying amounts
of charge sizes which were fed to the "Gelimat" in
individual containers. Dispersion ratings were -- i`~
consistent with the results given above, that is well
25 ~dispersed organic pigment in blown film, was obtained.
EXAMPLE 3 ~--
The procedures ~described in Example l were
repeated, this time with compositions I through P, using
t ~ the same conditions as described above. The
30 compositions were then used in formulations as organic ~ ~;
colouring pigments, being let down in a l melt index
;linear low dens~ity polyethylene and blown into a film of
l.5~ml. of thickness, the let down ratio being adjusted
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such that the final content of the organic pigment in
the film was 1~. Again, dispersion results were
assessed in the film products on a scale from 0 to 5 as
outlined above, with the following results being
5 obtained. ~-~
TABLE 3 `
PigmentDispersion
Composition Pigment Conc. (%)Ratinq _
I Yellow RG.S(l) 50 4
J Yellow RG.S(2) 50 3 ;~
K Green G 33 4
L Green G 50 4
M Blue NCG 33 4
N Blue G 33 4
o Blue G 50 3 ,~
P Red 2509 33 3 ~- -
.. , ~
In the above material, reference note (1) indicates
that the ingredients were fed directly to the high
-~ intensity mixer; reference (2~ denotes that the material
was ribbon blended. Each of the above compositions ~:
15 utilized a 12 melt index linear low density polyethylene~ ;
and as per Example 1, the ingredients were separately
fed except where indicated.
Generally speaking, different organic pigments have
different capabilities of being blended with a carrier~ ~
; ~ 20 resin; thus, a yellow pigment may be more easily blended~-
than eg. a~blue pigment, although this depends on the`;
individual organic compounds. From the above table, ~
however, it will be noted that in composition I, ; -
s~ compared to composition J, the former provided a -~
significantly higher dispersion rating at the same
amount of pigment concentration compared to that which
was ribbon blended. Again, by following the techniques
of the present invention, satisfactory to very good
~`~ results were obtained for dispersion at high loading
ievels compared to that which could be obtained by the
prior art.
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EXAMPLE 4
The procedures of Example 1 were repeated, again
using the same conditions, but in this case, the
following ingredients were employed:
Organic Pigment 10
TiO 40
LLD~E 50
The organic pigment used in separate tests, was (a) -
a yellow RG5 and (b) a green "G" pigment, both of an ~ -
organic nature. No pre-blending of the ingredients was
carried out prior to addition to the high intensity
mixer. The resulting compositions were let down in a 1
melt index linear low density polyethylene and blown -~
into film. The film was studied for dispersion ~`~
~ ` characteristics and it was found that both compositions
!: ~ produced a very badly dispersed film, even at a level of
~; 15 10~ organic pigment. It is evident, therefore, that the
nclusion of additional additives such as the TiO
together with the organic pigments, has a detrimental
` affect on the quality of dispersion if the TiO2 is melt
dispersed~at the same time as the organic pigments.
