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Патент USA US2408697

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Patented Oct. 1, 1946
_ 2,408,696‘
UNITED STATE-S PATENT OFFICE
TREATMENT OF CARBON BLACK
Hugh M. Smallwood, Nutley, N. 1., assignor to
'
United States Rubber Company, New York,
N. Y.,~a corporation of New Jersey _
No Drawing. Application July 13, 1940,
Serial No. 345,429
'
8 Claims. (Cl. 106-307)
.
'2
.
treatment proceeds, this warm ‘zone passes
' The present invention relates to the treatment
throughout the entire body of the black. When
chlorine -is passed rapidly into large bodies of
carbon black, in which the heat developed in the
‘ flcation of certain carbon blacks which has the
property of yielding rubber mixes having abnor 5 reaction cannot be rapidly dissipated, mild ex
plosions may take place.
mally low viscosities and electrical conductivities,
The rate of passing chlorine through the‘car
together with exceptionally low hysteresis in the
bon black is, therefore, determined by, the size 4'
vulcanized condition. Other objects will be ap
and shape of the container used to confine the
parent from the following description.
'
This invention comprises treating hydrogen 10 carbon black. The rate may vary through a wide
containing carbon black with gaseous chlorine ; range without appreciably affecting the properties
of the ‘product. , The treatment is preferably con-'
under such conditions as will leave more than
of carbon black.
‘
'
An object of the invention is to obtain a modi- '
tinued until chlorine issues freely from the out
about 1% hydrogen chloride adsorbed on the
- let, i. e., until the reaction has been completed.
‘ lblack. Any carbon black prepared from natural
As noted above, considerable quantities of‘ hy
gas or from aromatic hydrocarbons can be used 15
drogen chloride are formed in the course of the
in the practice of this invention. - The treatment
treatment of the carbon black with chlorine. Part
of the black is spoken of as a treatment with
chlorine. Bromine, however, ‘can be successfully
of this hydrogen chloride is evolved as such, and
substituted for chlorine, but the latter is prefer
part is retained in the adsorbed state on the car- ,
. able because it is cheaper.
~
-
Carbon black treated according to the presen
invention gives a product which possesses the fol
20 bon black. The relative amounts of hydrogen
chloride evolved or retained on the black will
depend primarily on the temperature at which ‘
the treatment is carried out. The higher the
J temperature of treatment the'greater the propor
‘such low viscosity that much higher loadings of 25 tion of hydrogen chloride evolved, and the smaller
lowing advantages:
-
‘
(1) When mixed into rubber the product, has 1
the treated carbon black can' be used than of un
the proportion of adsorbed hydrogen chloride re
maining on the black. '
7 treated black.
Substantially all of the hydrogen chloride
(2) The mixture with rubber has an abnor
- formed in the process can be removed from the
-mally low electrical conductivity, and, when vul
canized, an abnormally low hysteresis.
80 carbon black by heating it in a stream of nitro
gen at temperatures in the neighborhood of 400°
The process consists in passing gaseous chlorine
C., or by washing the chlorinated black with hot
over the carbon black at any temperature ‘in the '
range from room temperature to 500° C.
water. Experiments have shown that the at-_
tainment of desirable properties in the rubber mix
Throughout ‘this entire range a reaction takes
place between the chlorine and the carbon black.
is dependent upon retaining as much adsorbed
The main features of this reaction will now be
hydrogen chloride on the black as is possible. The
described.
preferred treatment, therefore, consists in treat
-
Carbon black of the present invention contains '
several tenths of a per cent of hydrogen in a
state other than as loosely absorbed water. It
‘is ?rmly attached to the carbon, since this hy
drogen is only slowly driven off from the carbon
on heating in a current of nitrogen at 1000° C. ‘
ment of the carbon-black with chlorine at tem
peratures as ‘close to room temperature as pos
sible.
'
'
v
,
,
Treatment of carbon black with hydrogen chlo
ride under conditions which leave appreciable
amounts of hydrogen chloride adsorbed on the
When chlorine is passed through carbon black
at temperatures in the range given above, hydro ' 45 black are not equivalent: to the chlorine treat‘
ment, since the desirable properties are not ob
gen chloride is formed. In the lower part of the
tained in full measure.
,
temperature range evidence of a vigorous reac
Typical treatments of black are ‘given in Table
tion is found in the factthat appreciable wann
L‘blacks A, B, C and .13 being examples of 'my _
ing of the carbon black occurs at the point where
the ‘chlorine ?rst encounters ‘the black. As the 50 invention.
- “cases
Table I
A
Black treated with
B
01'
Oi!
O
,D
Oi!
- 1!
Hm
Brl.
Temp. 0! treatment _______________ -_ 340-4709 0... 161-173‘ 0--. Room
Room
110-18)‘ 0.
Time of treatment, min ........... __ 12o
Weight of black,
.
11)
an
10m
1900
120.
822.
in
2.6-
Per cent HI retaiilinnd
-
944
- 827
12
3.8. .
’
4.0.
‘large quantities of carbon black, to drop the black
In these experiments a typical channelblack
-'of the type used for manufacture ‘of tire treads
was Lused throughout. This black contained ap
slowly through an atmosphere of chlorine. _
The blacks prepared as above were compound
‘ed in rubber according to the following formula
proximately .2% . hydrogen‘ as determined by
(parts are by weight):
chemical analysis. The‘black was, in all cases, 15
con?ned in aé'glass container equipped with an. '
inlet for chlorine at one end and with an outlet
-
I
Parts
Smoked sheet
Treated black
at the other end for removal of evolved gaseous
Pine tar
products and excess chlorine.
In‘those cases in which experiments were made 20 Stearic acid
at elevated temperatures, theglass container was
.I
’
100
50
2
>
4.5
- Fast curing zinc oxide_-___. ______ ___s _____ __
'
'
'
2
Acetone-diphenylamine reaction product___ 1.7
heated externally by means of an electrical re
After the treatment, the
N,N'-diphenyl' p-phenylene diamine _____ -_ ‘0.3
amount of adsorbed, hydrogen chloride was de-'
Thiazole accelerator ____________________ __ ‘1.12
Sulfur
'
2.62
sistance furnace.
termined by the following procedure: ,
Five-gram samples of carbon black were re
The compounds of rubber and chlorinated
‘ ?uxed for thirty minutes with 150 cc. distilled
blacks were mixed as follows. Rubber was
broken down in the customary manner on a 12."~
water. The samples were then ?ltered while hot,
and washed six or seven times with 30 cc. por
mill with rolls maintained at' 200-250av F. The
tions of hot water. » The ?ltrate and washings 80 carbon black, treated or untreated ‘control. was
were combined, allowed to cool, and titrated with
then added in the customary manner, and mill
ing continued‘ with cutting until 'an intimate
mixture had been obtained. The remaining com
the washing failed to remove any further acid
pounding ingredients were then added in the
35 order given above. Experience indicates that the
from the black.
A detailed description of the preparation of
usual methods of- preparing mixes, common to
the art, are adequate to enable observation of
chlorinated carbonblack C will now be given. ‘
standardized ‘sodium hydroxide solution. ‘Pre
liminary experiments showed that prolonging _
~302 grams of a standard rubber channel black ._ the unique properties of chlorinated black.
The mixes were’ cured as usualin a steam .
was placed in a glass tube,'approximately 4 cm.
inside diameter and 75 cm long. The bottom of 40 heated platen press for 40 min. at 143‘0.
'
Table 11
.
‘ r
_'
o'
‘
I
n v
I
'
-
r
1
Above basemix containing ............... -_ Untreated control--- A.
'r-so
-11.4...
o.n
' s.
4.5.... $2.: ............ .- -4.s.--_ -4.e.
Electrical resistivity (ohm-cm.) ........... .. 2.5)(10' ............ .. 2X10‘-..
reaterthan10"-_ 1X1 ... 6X10‘.
Torsional hysteresis at can? I‘ .... .7; ...... .. .157 ............... -. .l48...-. .103 ............ -1. .l4_4....- .134.
the tube was constricted and ‘closed witha loose ‘so
plug of asbestos. At this point an 8 mm. glass
' tube had been sealed to the large tube. Com
mercial chlorine from a cylinder was introduced
The torsional hysteresis testis described in
Gerke et' al., U. B. P. 2,118,001. The electrical
resistivity was measured according to the tech
nique described in the Gerke et al. patent.
at the smaller tube attached to the large tube. ‘ _ In Table II note that the halogenated blacks.
(Formulas G. H and vJ) give higher electrical
resistivity and lower torsional hysteresis than
the control (li'orrnula'li')v containing untreated leading to a hood for removal of waste gases.
- black. Further. the black ‘treated with hydro;
Chlorine was passed through the column of car
gen. chloride (D, Formula I) gave very little low-1
bon black at a rate of approximately 50 to. per
ering of hysteresis and only a. four-fold chi-n86
minute for a period of 2 hours. A slight warm
in resistivity, even though it‘ contained'more ad-.
ing of'the blackwas ‘noticed during the course
sorbed hydrochloride than black A. '
of the-treatment, but apart from this, the tem
It will be noted from the foregoing data that
perature remained at room temperature. The
the chlorinated carbon black exerts a strong res
black so obtained was found to contain 4.0% ad
tarding action upon the vulcanization reac-_
sorbed hydrogen chloride by means of the an
tion, as judged by T-BO. This is due to the well
alytical procedure described above.
.
'known retardation of vulcanization by strong
Experience with this process indicates that
shape of container used for the black. and the‘ acids. This eifect can be overcome by adding to
the mix, along with the customary curing in
rate of streaming chlorine through the black, are
_' relatively unimportant. Temperature is of im
gredients, su?lcient basic material to neutralize
portance only insofar as vit controls the amount , the hydrogen‘ chloride contained on the black.
The basesusedinthisoperationmustbesuill
of hydrogen chloride remaining on the black.
ciently strong to form salts with hydrochloric
Various means of bringing the carbon into con- .
acid which do not retard vulcanization. Zinc tact with the ‘chlorine could be used without de
' parting from the-spirit of this invention. For 7| oxide is not a sufliciently strong base for this
- The upper end of the large tube was connected.
by means of- a ground joint,'to a smaller tube
example, 'it might be advisable. when treating
purpose. Sodium hydroxide is sumeiently basic,
2,408,090
(y
.
5 ,
'
6
a
_.
.
The carbon black treated by the present inven- ,
tion is to be distinguished from activated char
as are also the quaternary bases. Similarly, com
pounds such as triethanola'mine can be used ad- '
- vantageously for this purpose.
coal, which is not in the ?nely divided form such
as channel black, but is in a granular porous
The optimum amount of basic material is best
determined by preliminary experiments in rub
ber, rather than by calculation of the amount
01 basic equivalent to the acid adsorbed on the
carbon black. It has been found that the op
timum amountof base is rather'less than that.v '
equivalent to the acid content of the black. This 10
is probably due to the reaction of part of the
hydrogen chloride with the rubber hydrocarbon.
Alternatively, it may be that some of the hy
drogen chloride is evolved during the mixing
state.
‘
'
v
'
~
Having thus ‘described my invention, what I
claim and desire to protect by Letters Patent is:
1. 'A process which comprises treating ?nely
divided hydrogen-containing carbon black with
gaseous halogen for a time and at a temperature
su?lcient to leave more than about 1% hydrogen
halide adsorbed on the black. _
2. A process which comprises treating ?nely
divided hydrogen-containing carbon black with
15 gaseous chlorine for a time and at a temperature
operation.
sufficient to leave more than. about 1% hydrogen
chloride adsorbed on the black.
3. A process which comprises treating ?nely
In any event, the chlorinated black may be
mixed into rubber, and the excess acid may be
‘neutralized without any dis advantage to the re
sultant vulcanizate.
'
divided hydrogen-containing carbon black with
-
In these experiments the chlorinated black 20 gaseous chlorine at a temperature approximating
‘room temperature and for a vtime ,suilicient to
wasladded to the rubber as described above.
leave more than about 1% hydrogen chloride
After the black was completely incorporated, the
adsorbed on the black.
'
'
base‘was added. The mix was then blended for
" 5 min.
4. A processwhich comprises treating ?nely,
The curing ingredients were then added.
The following data were obtained. -
25 divided hydrogen-containing channel black ‘with
'
Table In
a
K
L
M >
N
Bass mix as above with ........... -.' 4 Untreated black.-. Chlorinated black -' Chlorinated black
Plum
.
7
.
(6.0% H01). _
a news bl'aOH
iTo?‘tlg‘unolomiue.
Chlorinated black‘
(6.0% HCl);
’
8.28..
~
...-.
(5.0% RC1).
‘10.3.
' OUBED W AT 143' C.
v
T-50--
_
_
>
.
>
.
\‘
-14.2-
+135.--“ ..... ..--
-17.4 ........... ..
Viscosity (Mooney).-.
as
80
5B
Electrical resistivity
2.5)(10'
Greater than 101).‘. Greater than 10".- Greater than 10". ‘.
Torsional hysteresisat 280° F ..... ._
.179
.275!
'
-
'
.
'
—-7.8.
--___--_--_- 65.
.y.- -
1
.100. ,
l
I This high value is due to the gross retardation of cure. Note that the mixes made from chlorinated black have
yisoosities less than um 01 the control (rel-mun x).
The low viscosity of the rubber mix, as a re
gaseous chlorine for a time and at a temperature
sult of chlorination oi the carbon black prior 45 sufficient to leave more than about v1% hydrogen’
chloride adsorbed on the black.
to mixing with the rubber, was further demon
5. Carbon black derived from hydrogen con- ‘
strated by the preparation of a mix of 100 of rub
tainlngcarbon black and containing more than
1% hydrogen chloride adsorbed on the black.
6. A process which comprises treating ?nely
ber,v 90 parts of chlorinated black containing
' (‘4.8% adsorbed hydrogen chloride, 2 parts of pine‘
tar, 4.5 parts of stearic acid, and 14 partsot a 50
divided hydrogen-containing carbon black with
30% aqueous solution of‘ sodium hydroxide. This
a gaseous halogen at a temperature and for a
mix had a viscosity’oi 116. A parallelgmix con
time su?lcientto produce about 4% of hydrogen
taining untreated carbon black would be so hard
halide adsorbed on the black.
as to be substantially non-plastic.
.
7. A‘ carbon black derlved'trom hydrogen-con
By the present invention there may’ be pre
pared a new type 01- carbon black which, when 55 taining carbon black and having about 4% hy
drogen halide adsorbed on the black.
'‘
compared to the conventional type of channel
'8. A process which comprises submitting chan
black, gives a mix with rubber of abnormally low
viscosity and electrical conductivity. together ‘- nel black to the action of chlorine for a time
and at a temperature su?icient to leave a _chlo-~ ’
with a vulcanlzate having abnormally low
hysteresis. Carbon blacks or the color grades 60 rlne content of more than about 1% on the
prepared according to thev present invention may I
also be used to give inlrsand lacquers oi greater
. ?uidity than do conventional carbon pigments.
treated black.
-
'
-
'
g
HUGH 1d. EMAIL-WOOD.
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