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Патент USA US2109592

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Patented Ma.‘ 1, 1938
2,109,592
UNITED STATES PATENT OFFlCE
3,109,592
PREPARATION OF PLASTICS
Maurice L. Macht, Jersey City, and Alan F. Ran
dolph, Montclair, N. J., assignors,
by mesne as
signments, to E. I. du Pont de Nemours & Com
pany, Wilmington, Del., a corporation of Dela- I
ware
No Drawing. Application April 1, 1936,
Serial No. 72,218
12 illaims. (Cl. 105-22)
This invention relates to the preparation of
binder ingredients well known in the art include
plastics and, more particularly, relates to a proc
ess whereby solid coloring matter or other solid cellulose esters such as‘ cellulose acetate and
minor ingredients of a plastic composition may - propionate, cellulose ethers as ethyl and benzyl
be uniformly distributed throughout a mass of cellulose, various polymerized organic com
pounds as polyvinyl resins, polymerized esters of
plastic without the necessity of using either vol
atile or non-volatile liquid.
In the plastics art, particularly in the prepara
tion of molding compounds, the working up of
10 the plastic in the substantial absence of liquids,
except for plasticizers which may be liquid, is be
coming more and more important. This method
of procedure usually involves kneading the com
acrylic and alkacrylic acids.
More specifically, the present invention com
prises, in connection ‘with the preparation of a
batch of plastic having a cellulose derivative as
the binder ingredient, the dry-grinding of a pig
ment or solid dyestu?’ in a ball- or pebble-mill 10
together with from 3-20, preferably 3-6, times its
ponents of a batch of plastic in a masticator mix _ weight of the cellulose derivative until the pig
15 er, such as a Banbury mixer, or other mixer ment or dyestuif is thoroughly commlnuted and
dlspersed through the cellulose derivative, adding 15
adapted to give the plastic a severe kneading ac
tion. An advantage of ‘this procedure is that it the resulting pulverulent mixture, or a suitable
requires only a matter of a few minutes kneading
to obtain a homogeneous batch of plastic. How
20 ever, this short time of kneading, or homogeniz
ing, otherwise highly advantageous, makes the
uniform incorporation of solid coloring matter,
or other solid minor ingredients of the composi
tion, in the plastic a difficult problem.
An object of the present invention is to provide
25
an economical and practical process for uniform
ly and thoroughly distributing and dispersing
solid coloring matter, or other solid minor ingre
dient, in and through a batch of plastic, without
30 the necessity of using a liquid. A further object
is to provide such a process wherein the uniform
distribution of the solid minor ingredient of the
plastic is insured even though the batch of plas
tic, as a whole, is only kneaded for a matter of a
35 few minutes. Other objects of the invention will
be apparent from the description given herein
after.
The above objects are accomplished according
to the present invention by dry-grinding a solid
40 minor ingredient, such as solid coloring matter,
solid lubricant, or the like, to go into a batch of
plastic, with a portion of the binder ingredient
of the batch until a homogeneous, pulverulent
mass is obtained, adding said pulverulent mass to
45 the rest of the material making up the batch,
and homogenizing the whole in any desired man
ner.
Throughout the speci?cation and claims the
term "binder ingredient” has been used to des
50 ignate that ingredient,_ or a combination of in
gredients, forming-with or without plasticizer,
the continuous phase of a plastic substance to
which its plastic properties are primarily due, as
distinguished from ?llers, pigments, dyestuffs,
lubricants, plasticizers, and the like. Typical
portion thereof, to a batch comprising the cel
lulose derivative and other compounds to be
compounded therewith, and proceeding with the
compounding of the batch by kneading in a
masticator mixer.
20,
The following examples are given to illustrate
the present invention, parts being given by
weight;
Example 1.—A batch of molding compound is to
be made having the following composition:
Parts
Cellulose acetate _________________________ __ .75
Dimethoxyethyl phthalate-___....___..______.._ 25
Zinc oxide _______________________________ __
Cadmium yellow_________________________ __
4 30
1
This batch is made by dry-grinding in a ball mill
the ?ve parts of solid coloring matter, (4 parts
zinc oxide, 1 part cadmium yellow) and 20 parts
of dry cellulose acetate ?ake until the coloring 35
matter is uniformly dispersed through the ground
cellulose acetate ?ake. The resulting pulveru
lent mixture is of almost impalpable particle size.
This pulverulent mixture is then combined with
the remaining 55 parts of dry cellulose acetate 40
?ake going into. the batch, in suitably com
mlnuted form, and with the 25 parts of di
methoxyethyl phthalate, the plasticizer for the
cellulose acetate, and the whole batch thus as?
sembled is processed by being kneaded in a 45
masticator mixer for a few minutes until there
is formed a homogeneous plastic mass.
I
.The plastic mass formed in- this manner will
be uniformly colored and, upon being broken
down into granular form and subjected to ordl-. 50
nary thermoplastic molding technique, it will
yield articles of uniform color, free from ‘visible
agglomerations of pigment particles.
In commercial practice it is more convenient to
55
2,109,592
2
coloring ethyl cellulose molding compound is
prepare the pulverulent mixtures in comparative
made by grinding together in a ball mill:
ly large quantities so as to furnish a standing sup
ply for use in successive batches of compound.
This is illustrated in the following example, in
which both pigments and dyestu? are simulta
neously processed.
Ethyl cellulose
Pounds
4.5
Titanium dioxide _______________ -l _______ .._ 0.5
5
A batch having the composition:
'
7
Example 2.-—A cellulose acetate molding com
pound of the following composition is to be
Parts
Ethyl cellulose ________________________ __ 100
Triphenyl phosphate __________________ __
4
Diamyl phthalate _____________________ __
8
Cellulose acetate _____________________ __ '15
Titanium dioxide
02
Dimethyl phthalate _______________ _-____ 25
may be assembled as follows:
formed:
._
7
Parts
10
‘Titanium oxide ______________________ _
0.053
Madder lake
0.021
v
‘
15 Alizarine purple lake B _______________ .. 0.001
Parts
'
'
_
98.2 16
tTriphenyl phosphate___________________ ..
For the purpose of preparing a‘: stock mixture
for the coloring of successive batches, the follow
ing ingredients are pulverized together in a ball
20 mill: '.
-
‘
-
Ethyl cellulose
v
1°
4
Diamyl phthalate
8
Pulverized mixture of- ethyl cellulose and
Grams
titanium dioxide ___________ -1. ________ __
The batch‘ so assembled is then processed by 20 kneading same in a masticator mixer for two
Cellulose acetate _________ __'___' _____ _.-.___ 3000
minutes whereby a plastic homogeneous and free
Titanium
from visible ‘color specks is obtained.
oxide ________ _;_ _____________ __
Madder lake
___
530.
_
210
25 Alizarine purple lake B ________________ __
10
'
Example 5.—-The following ingredients are .25
ground together in a ball mill until there is pro
duced a finely ground, uniform powder:
The resulting pulverulent mixture is made up
-
_
'
Pounds
of one part of solid coloring matter to four parts '
Polymerized methyl alpha methacrylate resin- 4
of cellulose acetate. After the dry-grinding has
Hydrated chromium oxide ______________ __.,__ 1 so
30 been carried out in a‘ manner analogous to that
in Example 1, the ‘pulverulent mixture is ready
This mixture will be referred to below as Mix
for use for the purpose of coloring large batches.
To make up an assembled batch having the
ture A.
composition set forth at the begimiing of this
35 example, which composition includes a total of
v
.
Similarly there are ground together the follow
ing ingredients:
'
I
Pounds
35
0.075' part of solid coloring ‘matter, the follow
Polymerized methyl alpha methacrylate resin. 9
ving will be used:
Stearic acid_____
-
_' v ,_
Parts
Cellulose acetate_____.__- _____ _‘__;'__4______ 74.7
40 Dimethyl phthalate _____ _;'__'___._ _____ __ 25
Pulverized mixture ____ __'___; _________ __
0.375
The batch thus made' up is processedin the same
manner as that of Example
1.
.
.
Example 3.--A batch of- molding compound is
45
to be made up according to the following formula:
} Parts
1
This mixture will be referred to below as Mix
ture
B. 1
-
'
-
40
It is desired to produce a homogeneous plastic
having the following formula:
‘
Part5
Polymerized methyl alpha methacrylate
resin
____
'
Diamyl phthalafe
100
~
Hydrated chromium oxide ______ __.. ______ __
- 1
Stearic acid ____________________________ __
2
Cellulose, acetate ______ _'__Y___‘_.._'..__‘_____- '78
This-formula is obtained by assembling together
Dimethoxyethyl phthalate____e ________ __ 18
4
the following:
50 Triphenyl phosphate _________________ __
Rhodamine RX
0.002
‘
.
45
26
'
50
Parts
Polymerized methyl alpha methacrylate resin_ 78
Diamyl phthalate ____________ _...'...'._ ________ __ 26
55
A stock mixture is made‘ up by ball milling to
gether 19 parts of cellulose acetate and one part
of Rhodamine BX until a uniformly colored,
homogeneous, impalpable powder has been
formed.
The complete batch is then made up
by‘assembling the following:
I
60
Cellulose
~
Parts
acetate ____________ __- _______ __ 78
Dimethoxyethyl phthalaten; _________ .._ l8
Triphenyl phosphate ____ __'_____.. _____ -_ 4
Pulverized mixture of acetate and dye
65
stuff
-....
0.040
Due to the cellulose acetate in the pulverized
Mixture
A-..
Mixture“
..___
Example 4.—A ?nely pulverized mixture of
ethyl cellulose and pigment for the purpose of
75
'
5
20 55
The batch so assembled is then processed in a
masticator mixer and yields a mass in which the
pigment and lubricant are completely and
homogeneously dispersed.
60
In the following examples are given combina
tions of dry, pulverizable, solid minor ingredi
entsv with dry, pulverizable binders (the latter
mentioned ?rst in each instance) which may be
pulverized together to give a pulverulent mix- 65
ture adapted to be assembled with other ingredi
ents to give a uniform, homogeneous batch of
plastic‘upon kneading for a short time:
mixture, there is a slight excess of cellulose ace
tate over the 78 parts called for in the formula
70 but the excess is negligible for practical purposes.
The ingredients thus assembled are then kneaded
in a Banbury mixer as in Example 1.
-
___>
Example 6
'
7o
Parts
Cellulose acetate ?ake __________________ __ 760
‘Titanium dioxide
Cadmium yellow #1 __________ __.. _______ ....
Rhodamine B extra .................... _..
1“)
48
2 75
2,109,592
Example 7
Parts
Cellulose acetate ?ake _____________ ___ _____ _. 3
Zinc oxide
1
Example 8
-
Parts
Ethyl cellulose ________________ ___ ______ _'__ 19
Oil Red 0_____
_
10
1
Example 9
'
Benzyl
-
cellulose
Parts
____
I
9
Titanium dioxide _________________________ .._ 1
15
Example 10
'
‘
-
Parts
Polymethyl alpha methacrylate ___________ __ 12
20
Ultramarine CU __________________________ __
Aluminum palmitate _____________________ __
'
1
2
Example 11
'
Parts
Polymethyl alpha methacrylate ____________ __ '7
Stearic acid ______________________________ __ 1
25
The above examples are merely illustrative and
the invention is broadly applicable to all binder
ingredients adapted to be ground to a pulverulent
condition. Among such binder ingredients are
the cellulose esters, the cellulose ethers, various
30 polymerized organic compounds such as esters of
3
solid plasticizers is likely to result in the mixture
calcing under the-heating‘and impact eifects of
grinding.
The proportion of binder ingredient, to solid
minor ingredient in the mix subjected to the
grinding step may be varied widely. Ordinarily,
it is preferred to useat leastthree times as much
by weight of the binder ingredient as the solid
coloring matter or lubricant. The process is ad
vantageous even when the proportion of binder 10
ingredient amounts to as much as 20 times the
weight of the solid. minor ingredient but prac
tically a proportion of 3-6 times the weight of
binder ingredient to solid minor ingredient has
been found most useful. It will be understood 15
that the solid minor ingredients, where more
than one is being used, may be ground together
with ‘the binder ingredient or the solid minor
ingredients may be ground separately with the.
binder ingredient to make two stock supplies of 20
pulverulent mixtures, one containing one solid
minor ingredient and one containing the other.
As far as the present invention is concerned,
it is immaterial whether a large amount of
binder ingredient and solid minor ingredient are 25
ground up to form a stock supply, or whether
the amount of these two ingredients ground up
is merely sufiicient for the particular batch of
plastic being made up at the time.
Aslwill be understood by those skilled in the 30
methacrylic and acrylic acid. Where a binder
ingredient is not adapted to be ground to pulver _ art, any of the grinding apparatuses commonly
used in the plastics industry ,will be adapted for
ulent condition at room temperature, such bind
making the pulverulent mixtures according to
er ingredient may be used in the present inven
35 tion by resorting to chilling. Also, in cases where
the ?rst step in the process of the present inven
tion. The conventional ball mill or pebble mill
the binder ingredient cannot be pulverized as a
practical matter, the present invention may be is preferred, although mills of other types, such
employed by grinding the solid minor ingredient as a hammer mill, may be used if adequate pre
with a binder ingredient which is pulverizable cautions are taken to avoid loss of ingredients
40 and compatible with the chief binder ingredient
which would alter the proportions and, further,
that the material be ground ?nely enough to ac
to be used in the plastic and which, in the pro
complish the purpose of the present invention;
portions it is to be used in the batch to be as
The particular method of kneading the ingre- sembled, is unobjectionable or at least tolerable
dients assembled for the batch to be made will be
as a constituent of the binder. Frequently the
45 proportion of pigment, or the like, to be intro
obvious to those skilled .in the. art. The knead
duced into a batch of plastic is so small that the ing will preferably be done in a masticator mixer,
amount of such foreign binder ingredient ‘to be such as a Banbury mixer, which is adapted to
give the vigorous kneading desired, although in
introduced with it would have no material influ
ence upon the batch as a whole.
50
}
Those skilled in the art will recognize that the
use of cellulose nitrate in the present invention
is subject to a certain amount of risk as it is
known to be a hazardous procedure to subject
nitrocellulose in dry form to grinding vor inten
sive kneading.
The minor solid ingredient of the plastic must
likewise beadapted to be reduced to pulverulent
condition by grinding. Solid coloring matter is
generally applicable in the process of the present
Likewise, such solid lubricants as
60 invention.
stearic acid, aluminum palmitate, aluminum
stearate, zinc stearate, carnauba wax, candelilla
wax, parai?n wax, and the like. ‘The use of liq
uid lubricants such as mineral or vegetable oils
65 in the preliminary grinding step is not feasible _
in the present invention. Also, liquid plasticizers
must de?nitely be eliminated from the mix sub
jected to the grinding step and, in general, even
solid plasticizers must not be introduced into
70 the mixtures subjected to the grinding step. The
reason for this is that the perfect dispersion of
the pigment or lubricant is achieved only when
a free ?owing pulverulent mixture is obtained
which can be readily distributed in the assem
75 bled batch of plastic, while the presence of even
some instances the use of mixing rolls, or other
mixing equipment, is feasible.
'
The ingredients, and proportions thereof, go
ing to make up the batch with the pulverulent 50
mix of binder ingredient and minor solid ingre
dient, will be determined by the usual considera
tions in arriving at a batch compositiom What
ingredients or what proportions are used does
not have a critical bearing on the present inven 55
tion. However, one of the chief advantages of
the present invention is that the batch can be
worked up by momentary kneading without using
any liquid at all.
Since many plasticizers are 60
liquids, frequently-the assembled batch will con
tain liquid plasticizer. On the other hand, as
volatile liquids or non-volatile liquids are in no
way necessary to get a perfectly homogeneous
batch and-their use, in general, is uneconomical ‘
and disadvantageous where it can be avoided,
the process of the present invention will almost
invariably be carried out from beginning to end
in the absence of liquids other than the plas
ticizer which may be a liquid; in certain plastics
plasticizer may be omitted entirely vas those
skilled in the art will understand.
This invention provides a simple, inexpensive,
and satisfactory means for the preparation of >
plastic‘s'whereby solid minor ingredients such as
75
2,169,592
4
pigments, dyestuffs, and lubricants may be dis
tributed and dispersed homogeneously and com
pletely throughout a batch of plastic without the
necessity -of using volatile'or non-volatile liquid
ingredients. A further advantage of the present
invention is that no extra kneading or mixing of
'the plastic as a whole is necessitated and yet the
dispersion of the solid minor ingredients is com
plete and there are no color specks, nor is there
10 any objectionable non-uniform dispersion of solid
ingredients in the plastic.
'
As many apparently widely different embodi
ments of this invention may be made without de
parting from the spirit and scope thereof, it is
to
be understood that the invention is not limited
15
to the speci?c embodiments thereof except as
de?ned in the appended claims.
'
We claim:
1. In the process of preparing a batch of solid
20 homogeneous plastic having a solid minor ingre
dient uniformly dispersed therethrough, the steps
comprising dry-grinding in the absence of sol
vents and plasticizers the solid minor ingredient
ingredient of the batch, said portion amounting
to at least three times the weight of said minor
ingredient, until a homogeneous pulverulent mix
ture is obtained, ‘adding said pulverulent mixture
to the remainder of the binder ingredient and any
other ingredients making up the batch, and se
verely kneading and masticating the whole until
a homogeneous plastic is obtained.
6. In the process of preparing a batch of solid _
homogeneous plastic having solid coloring matter 10
uniformly dispersed therethrough, - the steps
comprising dry-grinding in the absence of . sol
vents and plasticizers the solid coloring matter of
the batch with a portion of the organic binder
ingredient of the batch, said portion amounting to
at least three times the weight of said solid color
ing matter, until a homogeneous pulverulent mix
ture is obtained, adding said pulverulent mixture
to the-remainder of the binder ingredient and any
other ingredients making up the batch, and
severely kneading and masticating the whole un
til a homogeneous plastic is obtained.
7. In the process of preparing a batch of solid
homogeneous plastic having a solid lubricant uni
formly dispersed therethrough, the steps com
20
of the batch with a portion of the organic binder
ingredient
of the batch until a homogeneous pul , prising dry-grinding in .the absence of solvents
25
verulent mixture is obtained, adding said pulver
and plasticizers the solid lubricant of the batch
ulent mixture to the remainder of the binder with a portion of the organic binder ingredient
ingredient and any other ingredients making up of the batch, said portion amounting to at least
the batch, and severely kneading and masticat
three times the weight of said solid lubricant,
30 ing the whole until a homogeneous plastic is ob
until a homogeneous pulverulent mixture is ob
tained.
tained, adding said pulverulent mixture to the re
2. In the process of preparing a batch of solid
of the binder ingredient and any other
homogeneous plastic having solid coloring matter mainder
ingredients making up the batch, and severely
uniformly dispersed therethrough, the'steps com
kneading and masticating the whole until a ho
35 prising dry-grinding in the absence of solvents mogeneous plastic is obtained.
and plasticizers the solid coloring ~matter of the
8. In the process of preparing a batch of solid
batch with a portion of the organic binder ingre
homogeneous plastic comprising an organic bind
dient of the batch until a homogeneous pulver
er ingredient, a plasticizer therefor, a solid lubri
ulent ‘mixture is obtained, adding said pulver
cant and solid ‘ coloring matter uniformly dis 40
persed therethrough, the steps comprising dry
40 ulent mixture to the remainder of the binder in
gredient and any other ingredients making up the grinding in the absence of solvents andplasticizers
batch, and severely kneading and masticating the the solid lubricant and solid coloring matter with
whole until a homogeneous plastic is obtained.
a portion of the binderingredient of the batch,
3. In the process of preparing a batch of solid said portion amounting to at least three times the 45
homogeneous plastic having a solid lubricant uni
combined weight of said solid lubricant and solid
45
‘formly dispersed therethrough, the steps com
coloring matter, until a homogeneous pulverulent
prising dry-grinding in the absence of solvents mixture is obtained, adding said pulverulent mix
and plasticizers the solid lubricant of the batch ture to the remainder of the binder ingredient and
with a portion of the organic binder ingredi
the plasticizer making up the batch, and severely 50
ent of the batch until a homogeneous pulver
kneading and masticating the whole until a ho
50
ulent mixture is obtained, adding said pulverulent mogeneous plastic is obtained.
mixture to the remainder of the binder ingredi
9. In the process of preparing a batch of solid
ent and any other ingredients making up the homogeneous plastic having, as the binder in
batch, and severely kneading and masticating the gredient, a cellulose ester and having a solid minor
ingredient uniformly dispersed therethrough, the
55 whole until a homogeneous plastic is obtained.
4. In the process of preparing a batch of solid steps comprising dry-grinding in the absence of
homogeneous plastic comprising an organic solvents and plasticizers the solid minor ingre
binder ingredient, a plasticizer therefor, a solid dient of the batch with a portion of the cellulose
lubricant and solid coloring matter uniformly dis
ester until a homogeneous pulverulent mixture 60
60 persed therethrough, the steps comprising dry
is obtained, adding said pulverulent mixture to
grinding in the absence of solvents and plastici
the remainder of the cellulose ester and any other
zers the solid lubricant and solid coloring matter ingredients making up the batch, and'severely
with a portion of the binder ingredient of the kneading and masticating the whole until a ho
batch until a homogeneous pulverulent mixture mogeneous plastic is obtained.
65
10. In the process of preparing a batch of solid
65 is obtained, adding said pulverulent mixture to
the remainder of the binder ingredient and the homogeneous plastic having, as the binder ingre
plasticizer making up the batch, and severely dient, cellulose acetate and having a solid minor
kneading and masticating the whole until a ingredient uniformly dispersed therethrough, the
homogeneous plastic is obtained.
steps comprising dry-grinding in the absence of 70
5. In the process of preparing a batch of solid‘ solvents and plasticizers the solid minor ingre
homogeneous plastic having a solid minor ingre
dient of the batch with a portion of the cellulose
76
dient uniformly dispersed therethrough, the steps
comprising dry-grinding in the absence of sol
vents and plasticizers the solid minor ingredient
of the batch with a portion of the organic binder
acetate until a homogeneous pulverulent mixture .
is obtained, addi‘ng said pulverulent mixture to
the remainder of the cellulose acetate and any 75
9,108,892"
,
,
w
'
5
other ingredients ma ng up the batch, and se-
12. In the process of preparing a batch of solid
verely kneading and masticating the whole until
a. homogeneous plastic is obtained.
homogeneous plastic having, as the binder in,
gredient, polymerized methyl methacrylate and
11. In the process of preparing a batch of solid
homogeneous plastic having, as the binder ingre-
having a solid minor ingredient uniformly dis-‘
persed therethrough, the steps comprising dry
dient, cellulose ether and having a solid minor in- grinding in the absence of solvents and plasti
gredient-uniformly dispersed therethrough, the cizers the solid minor ingredient of the batch
steps comprising dry-grinding in the absence of with a portion of the polymerized methyl meth
solvents and plasticizers the solid minor ingre- acrylate until a homogeneous pulverulent mixture
dient of the batch with a portion of the cellulose is obtained, adding said pulverulent mixture to
ether until a homogeneous pulverulent mixture is the remainder of the polymerized methyl meth
obtained, adding said pulverulent mixture to the acrylate and any other ingredients making up the
remainder of the cellulose ether and any other batch, and severely kneading and masticating the
ingredients making up the batch, and severely whole until a homogeneous plastic is obtained.
kneading and masticating thewhole until a homogeneous plastic is obtained.
MAURICE L. ‘MACHT. ‘
- ALAN F. RANDOLPH.
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