MELANGES-MAITRES, A VISCOSITE DETERMINEE, DE PIGMENTS DESTINES A LA COLORATION DE MATIERES THERMOPLASTIQUES

VISCOSITY-REGULATED MASTERBATCHES OF PIGMENTS FOR COLOURING THERMOPLASTICS

Abrégé anglais

Viscosity-regulated masterbatches
for colouring thermoplastics

Abstract of the Disclosure
Viscosity-regulated masterbatches which contain 10 to
49% of a pigment, 2 to 40% of a polyolefin wax, 20 to
85% of a copolymer of ethylene and vinyl acetate, and
0.5 to 10% of colloidal silicic acid.

Revendications

CLAIMS:

1. Viscosity-regulated masterbatches which contain 10 to
49% of a pigment, 2 to 40% of a polyolefin wax, 20 to 85% of
a copolymer of ethylene and vinyl acetate, and 0.5 to 10% of
colloidal silicic acid.

2. Masterbatches according to claim 1, which contain 15 to
30% of a pigment, 5 to 20% of a polyolefin wax, 35 to 65% of
a copolymer of ethylene and vinyl acetate, and 3 to 8% of
colloidal silicic acid.

3. Masterbatches according to claim 1, which contain a
polyethylene wax as polyolefin wax.

4. Masterbatches according to claim 1,which contain
an ethyl/vinyl acetate copolymer with a vinyl acetate
content of 15 to 40%.

5. A process for the manufacture of viscosity regulated
masterbatches according to claim 17 wherein 10 to 49 parts of
a pigment are intimately mixed with 2 to 40 parts of a
polyolefin wax and 20 to 85 parts of a copolymer of ethylene
and vinyl acetate and 0.5 to 10 parts of a colloidal silicic
acid.

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6. A process according to claim 5, wherein a start is made
from 15 to 30 parts of a pigment, 5 to 20 parts of a poly-
olefin wax, 35 to 65 parts of a copolymer of ethylene and
vinyl acetate, and 3 to 8 parts of a colloidal silicic acid.

7. A process according to claim 5, wherein a polyethylene
wax is used as polyolefin wax.

8. A process according to claim 5, which comprises the use
of an ethylene/vinyl acetate copolymer with a vinyl acetate
content of 15 to 40%.

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Description

~6~1333

I~ is known to colour ~.hermoplastics by means o~ pigrllented
plasticised compounds~ commonly known as masterbatches, or
with pigment preparations, This method :is always employed
whenever it is not possible to attain any satisfactory dis-
tribution of the pigment in the end product in the given
method o processing plastics granulates when pure pigments
are used for the colouration, These masterbatches are normally
composed of mainly inorganic pigments and a polymer of ~he
same kind as that of the material to be coloured. Master-
batches based on organic pigments usually contain very much
lower concentrations of pigment.

Organic pigments in powder form have generally a substantially
larger specific surface area than inorganic pigments and in
addition exhibit much greater differPnces in behaviour during
processing. In particular, they influence the so-called melt
viscosity of high molecular weight polymers to a very much
greater extent than inorganic pigmen~s,

For practical reasons~ commercially available masterbatches
which contain a polymer or a wax as carrier ma~erial are
manuactured with a homogeneous pigment concentration for
pigments which often vary very greatly in their behaviour.
This has the disadvantage that, during the processing to the
end product~ the polymer to be coloured and the masterbatch
used for the colouration have different melt viscosities, as


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a consequence o~ which the rap~d attaimnen~ of a homogeneous
Einal colouration is hampered or even prevented. Additional
steps are ~hen necessary to attain the desired homogen~ity.


A urther disadvantage of the commercially available master-
batches is to be observed in the fact that they can be used
in each case only for one particular polymer and one particu-
lar method of processing. This means a large number of pro-
ducts for the ultimate processer.


The present invention provides ~iscosity-regulated master-
batches which are substantially free of the shoxtcomings
mentioned above and which contain
to 49% of a pigment
2 - to 40% of a polyolefin wax
to 85% of a copolymer of ethylene and vinyl acetate, and
O. 5 to 10% of a colloidal silicic acld.


Preferred masterbatches are those which con~ain
to 30% of a pigment
to 20% of a polyolefin wag
to 65% of a copolymer of ethyl-ene and vinyl acetate and
3 to 8% of a colloidal silicic acid.


The pigments on which the masterbatches are based can be~ or
example~ inorganic pigments~ such as carbon black, ~itanium
dioxide9 iron oxidey chromium oxide green, molybdate orange

or ultramarine
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Organic pigrnents~ however, are preferred. These can belong to
the most widely different chemical classes. Examples of suc~
pigments are: azo, methineg azomethine, phthalocyanine, nitro,
perinone, perylenetetracarboxylic acid derivatives, dioxazine,
~hioindigo, iminoisoindolinone or quinacridone pigments, as
well as metal complex pigmen~s of the most widely different
chemical nature. It is also possible to use mixtures of
different pigments.


As copolymers of ethylene and vinyl acetate there are pree_
rably used those which contain 15 to 40% of vinyl acetate.


As polyolefin waxes there are preferably used those with a ~-
molecular weight of 500 to lO,000, in particular of 3000 to
9000. Polyethylene, polypropylene or polyisobutylene wax may
be mentioned as examples.


The particle siæe of the colloidal silicic acid of silicon
dioxide is advantageously between 8 and 60 nm3 preferably
between 10 and 30 nm.


The masterbatches are obtained by intimately mixing, in parti-
cular by kneading, the components


It is especially;advantageous to convert the co~ponents into
a;homogeneous mixtu~e in a mixer, for example a PElugschar

mixer9 at 50_400 revolutions per minute for 5 to 30 minutes,
and to process this mixture to a granulate in a con~inuousIy


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operating kneading extruder at temperatures between 1.20 and
260C

A further preferred method o~ manufacture consists in mixing
the components in a fast rotating ~luid mixer at 400_3000 revo-
lutions per minute for 2 to 20 minutes and subsequently granu_
lating the mixtur~ in a doublè screw extruder with a large
length/diameter ratio and/or with kneading elements, at tempe-
ratures between 120 and 260C, in particular bet~een 120 and
260C.

Mast~rbatches are obtained in the fonm of break_resis~ant and
abrasion_resistant granulates of readily con~rollable fonn an~
size They can be conveyed pneumatically and stored without
problems arising. They are characterised by a very wide
applicability. Whereas the majority of the masterbatches
currently on the market are suitable only for coIouring one
:
polymer, the preparations of the present invention can be used
for inCOL~pOratiOn in the most widely diEerent kinds of plas~
tic materials, in particular in polyoleins, polyvinyl
chloride7 polystyrene copolymers, polyamides ~nd thermoplastic
polyesters
': . ' '~: ' .
A further~material advantage of the masterbatches of this in- -
.
vention is that the melt viscosit~ can be adjusted to the
desired opt~mum value by vaxying on the one hand the amounts
.. .
o~ viscosity-lowering polyole~în wax and on the other Qf


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3L~6~33

viscosity-increasing silica gel. The often consi.dcrably
varying ef~ect on ~he melt vi.scosity exerted by orgal~ic
pigments can thereby be compensated, and this makes it
possible to create a range o masterbatches which is charac_
terised by a uniform rheological behaviour,


In the following Examples the parts and percen~ages are by
weight, unless indicated to the contrary.




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~E~ :

65 parts of an ethylene/vinyl acetate copolymer ~trade mark:
Microthene MU 760), 5 parts of a polyethylene wax (e.g. poly~
ethylene wax 190-Plv.) and 10 parts oE a colloidal silicon
dioxide are mixed with 20 parts of the a7o pigment C.I~ Red
144 for 10 minutes in a Pflugschar ~ixer~ ~ -



The mixture is kneaded in a continuous kneader (system Lis~) ;
at cylinder temperatures of 120-180C and converted into a
granulate. Ihe end product has a melt index of 32.6. Then
2~5 parts of the masterbatch are mixed in a drum with -
9705 parts of a polyethylene with a ~elt flow index of 2 and the
mixture is blo~n to sheets in an extruder. Sh&ets of a homo-
geneous colo~r are obtainedO
: :'.
~!i!~ ' . :' . :

65 parts of an ethylene/vinyl acetate copolymer (trade mark:
Microthene MU 760)~ 10 parts of a polyethylene wax and 5 parts
of a colloidal silicon dioxlde are mixed with 20 parts of the
azo pigment C.I. Yellow 93 for 10 minutes in a ~ lugschar
mixer. The mixture is kneaded in a continuous kneader (system
Lis~) at temperatures of 180-240C and converted into a
granulate.


: .
~ The end pr~duct has a mel~ index of 28. Five parts of this
:
product a~e mix~d with 95 parts of a polyvinyl chloride with


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a K-value of 70 and a plasticiser content of 35% and rolled
to a sheet, The sheet has a homogeneous colour.



To colour poly~ers in powder form lt is advantageous to
comminuce the preparations obtained isl Example 1 or 2 by
appropriate methods uncil the required par~is:le size is
obtained, preferably by low temperature grinding.

.
~ .

65 parts of an ethylene/vinyl acetate copolymer (trade mark~
Microthene MU 760), 10 parts of a polyethylene wax and 5 parts
of a colloidal silicon dioxide are mixed with 20 parts of the
azo pigmenc C.I. Red 166 for 2 minutes in a fluid mixer. The
mixture is kneated in a con~inuo~s double-shaft kneader (type
Leistrit~ at temperatures of 140-180C and converted into a
granulate. The end product has a melt index o~ 51. Five parts
of~this product are mixed wlth 95 parts of a polye~hylene
terephthalate~and spun at 295C in an extruderO The filament
obtained has a uniform colouration of excellent fastness ~ .
propertiesO



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57.4 parts of an ethylene/vinyl acetate copolymer ~trade mark:
Microthene MU 760), 17.5 parts of a polyethylene wax and
5 parts of ~ colloidal silicon dioxide are mixed with 20 parts ;~
of the phthalocyanine pigment C.I~ Blue 15 for 10 minutes in
a Pflugschar mixerO The mixeure is kneaded in a continuous
kneader (system List) at temperatures of 160 to 200 C and
converted into a granulate. The end product has a melt index
of 35. one part of this product i5 mixed with 99 parts of a
polyamide and injection moulded in a screw injection ~oulding
machine. Blue moulded pieces o~ homogenous colouration are
obtained.
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.
The following ~able shows with reference to three pigmen~s
,,
how on the one hand the melt index can be lowered by
increasing the content Oe silicic acid and On the other can
be raised by increasing the wa~ content.




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:~66Z333
_ _ _
CDI. Pigment CoI~ Pigment C.I. Pism~nt .
~ed 144 Green 7 _ Black 7
No MFI5 MFI5 _ _
_ _ _ _
80 parts of ethylene/
5 vinyl acetate copolymer 42.3 33.9 _
~0 parts of pigment
75 parts of ethylenet
vinyl acetate copolymer
6 20 parts of pig~ent 35.6 25~6 _
5 pares of colloidal
sio2
70 parts of ethylene/
vinyl acetate copolymer
7 20 parts of pigment 24.1 20.5 _
10 parts of colloidal
sio2
75 parts of ethylene/
vinyl acetate copolymer
8 20 parts of pigment 47.5 41.3 _ ..
5 parts of polyethylene i .
wax
70 parts of ethylene/
vinyl acetate copolymer
9 20 parts of pigment 58.7 51.4 _
10 parts of polyethylene
wax
60 parts of ethylene/
: vinyl acetate copolymer
10 20 parts of pigment 86~8 80.1
20 parts of polyethylene .
wax
60 parts of ethylene/
: 11 vinyl acetate copoly~er _ _ 4.5 : .
: 40 parts of pigment -
50 parts of ethylene/ :
~ vinyl acetate copolymer :
:: 12 40 parts of pigment _ _ 4.7 ~: :
~ : ~; 10 parts o- polyethylene ~ ;

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~(~,66833 `
. _ .. _. . .. _ _
C.I. Pigment C.I. Pigment CoI~ Pigment ::
No Red 144 Gre~n 7 Black 7

~FI5 MFII- MFI
_ _ _ _ ~ ~ . 5
40 parts of ethylene/
vinyl acetate copolymer : :
13 40 parts of pigment _ 10.2 -
20 parts of polyethylene

20 parts of ethylene/ . . .-
vinyl acetate copolymer
14 40 parts of pigment _ _ 19.3
40 parts of polye~hylene .~




* Melt flow index accordlng to ASTM 1238~62

~ , ' .

325 kg of an ethylene/vinyl acetate copolymer (trade mark:
Microthene MU 760)~ 50 kg of a polyethylene wax and 25 g of a
colloidal silicic acid are mixed ~ith 100 kg of the disazo
plgment C.I. Yellow 93 for 15 minutes at 100 rpm in a
2000 litre capacity Pflugschar mixer. The mixture is kneaded
in a double-shaf~ kneader at temperatures between 100C and
250C and converted into a granulate. : ~.
'~ ' .' ',
Ibe end product has a melt index of 47. T~o parts of this
product are mixed with 98 parts of a styrene/butadlene
copolymer and extruded to a sheet~ The extruded sheet has a
u~iform ~olouratlonO ;.


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