Note: Descriptions are shown in the official language in which they were submitted.
f(354
The ~esent lnvention relate~ to a reso~cinol in
filler pXepa~ations useful in rubbe~ adhesion ~ixtures for
the better adhesion o~ ~ubber yulcani~ates to metal textile
or glass ~ibxe structures.
In particular the ~resent invention relates to a
process for the production of such a preparation.
This application is a divisional application of
copending application No. 369,997, filed February 3, 1981.
It is known that to improve the stability of vulcani-
zed moulded rubber articles, as ~or example, tires, conveyorbelts, V belts and hoses against mechanical deformation, they
are reinforced with inserts. These composite articles have
inserts of textile fibres or textile fibre structures such as
fabrics or fleeces, or metal wires or metal wire structures,
as for example, steel cord, which can also have coatings of
brass, zinc or the like. Glass fibres or glass fibre struc-
tures have also been used as insert materials.
The rigid anchoring or adhesion of the insert
material to the rubber vulcanizates is important so that a
long service life of the dynamically stressed moulded articles
is attained. Thus, it is known that in order to attain a high
degree of adhesion, the filler carbon black in the rubber
mixtures partially replaced by a silica filler (see German
Patent No. 1,620,786). As is known, the adhesion can be
further improved substantially by adding components capable of
forming synthetic resin, such as phenol and/or amines and al-
dehydes or compounds splitting off aldehydes, to the rubber
nuxtures. Resorcinol and hexamethylene, tetramine (see British Patent
No. 801,928 and French Patent No. 1,021,959), when~ required in combination
with a silica filler (see German Auslegeschrift No. 1,078,320) are in wide-
spread use as resin-forming co~ponents in rubber adhesion muxtures.
Because of its poox dispe~sibility resorcinol is
~ ~S~5~
difficult to process in rubber adhesion mixtures Therefore,
more readil~ dispe~sible mixtures of resorcinol with a silica
filler (see German Patent No. 1,031,478~, as for example the
product supplied under the trademark Cofill II by DEG~SA,
which is a 1:1 mixture of resorcinol and a specific silica
filler, are used in most cases. In fact, the resorcinol,
which usually is in the form of lumps or platelets, is homo-
geneously distributed in this product. However, this product
also has disadvantages. Thus, for example, when using it an
undesirable dust formation can result.
The mixture also reduces the tendency of the re-
sorcinol to sublime out of the rubber mixture at the usual
processing temperatures only slightly or not at all so that
dust extraction plants are required to keep the ambient air
clean. Moreover, easy dosability and fluidity of the powdered
product leave a lot to be desired.
The present invention provides as disclosed and claimed
in copending application No. 369,997 a resorcinol-containing
preparation which is homogeneously distributed, readily
fluid and dosable, and which preferably does not form dust
on being weighed; and mixed in and is well dispersible in
rubber mixtures and whose resorcinol component shows reduced
sublimation, without impairing the quality of rubber articles
produced with these preparations, i.e., particularly that
neither their rubber-technological properties nor their good
adhesion properties between insert or coating and vulcanizate
are reduced.
According to the present invention as disclosed and
claimed in copending application No. 369,997 there is provided
a resorcin-filler preparation which comprises resorcinol and
at least one carbon black in homogeneous distribution.
In one embodiment of the present invention the
5~
carbon black is a furnace black having a specific particle
surface area of approximately 120 square metres per yram, as
measured by nitrogen adsorption (DIN 66132), and electron-
microScopically determined average ~rimary particle size of
20 to 45 nm and a dibutyl phthalate absorption (DIN 53601) of
45 to 130 ml, which is present in an amount of 30 to 70
parts by weight per 70 to 30 parts by weight of resorcinol
made up to 100 in each case.
~n another embodiment of the present invention the
carbon black is a furnace black which has a specific particle
surface area of approximate~y 7~ to 85 square metres per gram,
an electron-microscopically determined average primary par-
ticle size of 24 to 30 nm and a dibutyl phthalate absorption
(DIN 53601) of 110 millilitres per 100 grams, which is present
in an amount of 50 parts by weight per 50 parts by weight of
resorcinol.
The present invention also provides a rubber adhesion
mixture for improved adhesion of rubber vulcanizates to metal,
textile and glass fibre structures containing the aforesaid
resorcinol in filler preparations.
The present invention further provides as disclosed
and claimed in copending application No. 369,997 a process
for producing the resorcinol filler preparation in which a
resorcinol in the form of platelets or in a similar form and
carbon black in the form of a powder are mixed in a high-
speed mixer for several seconds, b) the product formed is
processed in a low-speed mixer to a preparation assuming sub-
stantially a bead-like structure and in order to attain the
bead-like or granular structure of the preparation in the
process step a) the resorcinol is reduced to an average par-
ticle size of 0.10 to Q.4Q ~m or when the resorcinol is pre-
sent and used as a powcle~ havin~ sa~d avera~e particle sizes
3~
only a short-term treatment in the high-speed mixer is per~
formed or only the process step b) is carried out. Suitably,
step Ib~ is carried out in ~ closed cylindrical vessel having
an inside diameter of approximately 2 metres and at a speed
be-tween 10 and 20 r.p.m. and a residence time of 1 to 5
hours. ~lternatively, step b) is carried out in the re-
volviny drum of a drying beading device.
According to the present invention of this applica-
tion there is provided a process for producing a resorcin-
filler preparation in which carbon black is put into a mixercapable of high-speed performance and provided with a heating
device, and when required with a
- 3a -
3s~
coolinq device, as well as with a propeller-type or rough
mixing tool, resorcinol is liquefied by heating, the
liquid resorcinol is fed into the fast running, heatecl mixer in
batches or continuously, the step for forming the preparation
is thus initiated, continued and completed until beads are
formed and the beads are cooled or allowed to cool in -the
running mixer until they are free from tackiness.
Rubber adhesion mixtures and mixtures based on
synthetic and/or natural rubber which contain - in addition
to the usual mixture ingredients such as sulphur, accelerators,
fillers, plasticizer(oil), antiagers, antioxidants, metallic
oxides, stearic acid and similar known mixture ingredients,
particularly the aldehydic compounds or compounds splitting
off aldehydes, such as hexamethylene tetramine or paraform-
aldehyde, which Eorm resins with resorcinol. It is a known
fact that the adhesion mixtures are used for improved adhesion
of the vulcanization products produced therefrom to metal,
-textile or glass fibre structures and inserts or coatings.
While carbon black is used in powdered form for
practical and economic reasons, the resorcinol can be used in
various forms as described hereinbefore. It has been found
that if it is desired to obtain the preparations according to
the invention in the form of beads or granulates, the resorcinol
must have an average particle size between approximatel~ 0~10
and 0.~0 mm or it must be reduced to these par icle sizes during
the first process step referred to as a). Particle sizes
smaller than approximately 0.10 mm impede or prevent the formation
of beads or granulates. When the average particle sizes are
larger than approximately 0.40 mm, then no homogeneous beads
(in size and shape) or no corresponding granulates are ob-tained.
The particle sizes are determined by sieve analysis
and the evaluation of the sieve analysis permits the average
par-ticle sizes -to be computed (see ASTM D 1511-74), As mentioned
hereinbefore, in a favourable embodiment the resorcinol can
also be used in a liquid form, i.e., in the molten state.
The ratio by weight of carbon black to resorcinol in
-the preparation according to the invention may vary within
wide limlts. Thus, the upper limit of this ratio can be 95 to 5O
For practical reasons the ratio by weight of carbon black to
resorcinol is preferably between 70 to 30 and 30 to 70. When
required the lower limit may be fallen short of.
The ~resent lnventlon will be further illustrated by
way of the following production Examples.
Example 1
The starting products characterized hereafter were used:
carbon carbon carbon silica
black black black filler
no. 1 no. 2 no. 3
average
particle 1)
diameter
in nm 27 29 25 18
specific 2
surface area )
in sq.m/g 80 95 180 175
DBP number )
in ml/g 100 120 110 170
volatile 4)
components 1.0 6.0 14.5
filler type furnace gas gas precipi-
black black black tated
silica
) average value determined electron - microscopically and
with the aid of the partlcle-size analyzer TGZ3 of the firm
of Zeiss.
) determined with the nitrogen adsorption method according -to
DIN 66132.
3) dibutyl-phthalate adsorption according to DIN 53601.
) determined according to DIN 53552.
s~
3000 g of the carbon black no. 1 and 3000 g o~
resorcinol were mixed in a high-speed mixer at 1400 r.p.m. for
five seconds. In this short-term mixing step the resorcinol
which had consisted of approximately 5 x 10 mm platelets and
of lumps of a similar size, was converted along with the carbon
black into a homogeneous form while the resorcinol was
comminuted. The average particle size thus decreased to 0.21 mm.
This mixture was then put into a so-called drying bead drum
o~ cylindrical shape which had a diameter of 2 m and a length
of 50 cm, and rotated therein at a speed of 12 r.p.m. for
appro~imately 90 minutes. After this time a bead~like preparation
(preparation I) was removed from the drum.
Further bead-like preparations were produced in the
same manner always in a 1:1 mixture with resorcinol, i.e., the
preparation no. II with carbon black no. 2 and the preparation
no. III with carbon black no. 3. The most important properties
of the preparations I to III thus produced and, for comparison,
the 1:1 mixture according to the prior art (Cofill 11( ) of
Degussa) have been listed herafter:
Preparation No. I II III mixture
according
to the
prior art
powder density )
in g/litre 448 440 400 260
tamping density )
in g/litre 506 484 452 338
)measured according to DIN 53600
6)determined according to DIN 53194
Sieve Analysis
in Percent
Preparation No. I II III
_ _
larger than 1 mm lOt4 13.2 17.8
0.7 to 1.0 mm 14.6 15.2 14.4
--6--
5'~
0.5 to 0.7 mm 14.4 16.0 16.6
0.25 to 0.5 mm 26.4 24.8 27.0
0.125 to 0~25 mm 20.0 16.8 14.0
smaller than 0.125 mm 14.2 14.0 10.2
average par-ticle size
(in mm) 0.51 0.56 0.62
residue
after washing out the
resorcin with hot water,
in percent by weight 51.4 50.7 49.3
The three preparations according to the invention have
the following favourable properties. The preparations are
readily fluid, dust-free granulates and have a distinctly
higher powder density and tamping density. Particularly the
tamping densities of the preparations according to the invention
(i.e., the tamping densities corresponding to -those in practice)
in the range from 450 to 500 g per litre are noticeably more
favourable than those of the product according to the prior
art, i.e., 338 g per litre.
The following tests were carried out to prove a further
important advantage of the preparations according to the
invention, namely, the decreased sublimation tendency of the
resorcinol in the preparation.
~ x mple 2
10 g of each the resorcinol-filler preparations
according -to the invention and of the product according to the
prior art (for comparison) were weighed into a flat porcelain
dish and these samples were heated for 24 hours at 8 different
defined temperatures. After cooling the samples they were
reweighed and the loss in weight was computed in percent. The
following results for the loss in weight were thus obtained.
Loss :in Weight in ~ for
sublimation preparation preparation prepartion product
temperature ~ II III accord-
in C i.ny to
the pri-
or art
_ _
0,23 0,48 0,79 1,2
0,38 0,94 1,3 1,8
0,47 1,0 1,5 1,9
0,93 1,6 2,2 2,8
1,3 2,1 2,6 3,8
100 2,5 3,6 4,5 5,3
110 3,3 4,2 5,0 7,2
150 16,8 20,2 16,8 29,4
The products according to the invention show distinctly
more favourable values than the product according to the prior
art. The preparation I has the lowest losses in weiyht at all
the temperatures, i.e., it has the most favourable values.
Example 3
In order to exclude the effect of entrained water in
the test for sublimation tendency, three preparations were once
more produced from the same three kinds of carbon black in the
manner described in Example 1, Elowever, these carbon blacks
had been prev.iously dried at 125C. Furthermore, for comparison,
a product according to the prior art was produced from the
silica filler (which had also been previously dried in the same
manner~ and resorcin (1:1 mi.xture). The test for sublimation
was carried out at 70C. The test results again show a distinct
super.iority of the preparations according to the invention:
--8--
5 ~ 5 L~
Decrease ln Sublimation in ~ercent by Weight at 70~C
preparation preparation prior art
No. IV No. V 1:1 mixture
1:1 mixt~lre 1:1 mixture o-~ dried
of dried of dried silica filler
carbon black carbon black and
No. 1 and No. 3 and resorcin
resorcin resorcin
_
after 24 hours 0.32 0.46 1.04
after 48 hours 0.49 0.53 1.13
after 72 hours 0.63 0.67 1.38
after 96 hours 0.99 0.96 2.02
after 168 hours 1.46 1.67 2.37
E mple 4
A further variant in the production of -the preparation
according to the invention lies in that the solid resorcinol
lies in the form of platelets or lumps is not used as the
starting product but that the resorcinol is first liquefied
by heating and according to experience the resorcinol assumes
temperature of approximately 120C, whereupon 480 g of the carbon
black no. 1 described in Example 1 are put into a high-speed
mixer having a propeller-type mixing tool, the speed being 500
r.p.m. The heating jacket of the mixer is charged with hot
water or steam of approximately lOO~C. 520 g of the liquid
resorcinol are then added while the mixer is running. As the
result of the intensive mixing process beads are forming
while their temperatures decrease until they are no longer sticky.
After further cooling, the final product is obtained. The
following properties of this product are determined by sieve
analysis and by defining the powder density and the tamping
density.
;o
5~
Sieve Analysis
in Percent
larger than 2 mm 10.8
1.0 to 2.0 mm 50.8
0.7 to 1.0 mm 20.8
0.5 to 0.71 mm 12.6
0.25 to 0.5 mm 4.6
0.125 to 0.25 mm 0.2
smaller than 0.125 mm 0.2
average particle size (in mm) 1.30
powder density (DIN 53600) 680 g/litre
tamping density (DIN 53194) 780 g/litre
Preparations having particularly high powder densities
are obtalned in this manner. It is assumed that these high powder
densities are attained because the liquid resorcin can penetrate
the interstices formed by the carbon black and is fixed therein.
The production variant of this Example can also be
carried out continuously. For example, carbon-black beading
machines li~e t~ose described in the German Patent No. 2,147,503
can be used with advantage for this purpose.
Example 5
If the premix is ground in a drying bead drum instead
of the second step of the trea~ent described in Example 1,
an optimal distribu-tion of the resorcinol on the carbon black
surface is obtained but the grinding causes the product to loosen
up substantially and the product then has a very low and thus an
unfavourable powder density.
In order to avoid this disadvan~age, the following
production variant was used.
The resorcinol which was in the form of 5 x 10 mm
platelets and lumps was ground in a pinned disc mill to an average
particle size of 0.17 mm. The proportion of resorcinol having a
--1.0--
particle size smaller than 0~125 mm was 33~.
3000 g of -this finely ground resorcinol were mixed with
3000 g of carbon black no. 1 from Example 1 in a high-speed
mixer. The mixing time was 7 seconds (and should generally be
between 5 and 10 seconds) and the speed of the mixing tool was
1400 r.p.m. After removing this preparation from the mixer it
had the following test values:
powder density 301 g/litre
tamping density 375 g/litre
These values of the powdered preparation according to
the invention still surpass the values of the mixture according
to the prior art in Example 1.
The preparations are used with technological advantages
in so-called rubber adhesion mixtures, i.e., rubber mixtures which,
in the vulcanized state, strongly adhere to inserts or coatings
of 1) textile structures of fibres, threads, wires, yarns, fabrics,
webs and the like from -textile fibres of natural or synthetic
origin, 2) of metal structures and particularly of steel struc-tures
or 3) of glass, particularly of silicate glass. Said fibres
) threads, wires, etc., include particularly synthetic products of
polyesters, as for example, polyethylene glycol terephthalate,
of polyamides, as for example, polyamide-6, polyamide-6,6,
polyamide-6,10, polyamide ll and polyamide-12, also of polyamides
such as polv-p-and/or m-phenylene terephthalamide or isophthalamide
and of regenerated cellulose (viscose). The metal structures
preferably include metal wires and particularly uncoated, brass-
plated or zinc-coated steel cord.
The following Examples show the extent to which good
adhesion values can be attained from rubber mixtures which had been
0 produced with the use of the preparations according to the
invention.
Examples of Application
A) The followin~ four rubber mixtures were produced
from the mix-ture ingredients listed hereafter and were tested
for adhesion. The amounts are in parts by weight. The mix-ture
noO 4 is -the comparison mixture.
Ingredients Mixture No.
1 2 3 4
_ _ . _ . _ . . .. . _ _ .
natural rubberl) 30 30 30 30
polyisoprene rubber ) 70 70 70 70
stearic acid
poly-2,2,4-trimethyl
-1,2-dihydro-quinoline
plasticizer oil, highly
aromatic, cold setting
point + 0C 4 4 4 4
HAF-Black N 330 ) 45 45 45 45
granulated, activated,
precipitated silica
filler 3) +) 15 15 15 12.5
zinc oxide 6 6 6 6
lead oxide 2 2 2 2
preparation no. I of
Example 1 5 - _ _
preparation no. II of
Example 1 - 5
preparation no. III of
Example 1 _ - 5
mixture according to the
pri+o)r art (see Example _ . - 5
benzothiazyl-2-di-
cyclohexylsulphen-
amide 0.7 0.7 0.7 0.7
hexamethylene tetramine
containing 3P6 of SiO2 1.5 1.5 1.5 1.5
sulphur, insoluble 4 4 4 4
) Producer: Degussa, Postfach 2644,
D 6000 Frankfurt/Main 1.
-12-
3s~
) ribbed smoked sheets No. l
60 Mooney L 4 (lOO~C)
con-tent of zinc-pentachloro thiophena-te 0.2
) with a cis-1,4 content of 98-99~
3) average primary particle size 18 ~m;
specific surface area (DIN 66132)
175 sq m/g (Ultrasil ~ VN3 of Degussa)
In accordance with the ASTM Standard D2229-73 the
four rubber mixtures were then vulcanized and tested together
with or on brass-plated steel cord. The following test
conditions were chosen:
Construction of the brass-plated steel cord:
7 x 3 x 0.15 mm.
Length of embedding the steel cord in rubber: 1 cm
Vulcanization temperature: 145C.
Vulcanization time: 100 minutes.
The tests were carried out with a tensile testing
machine according to DIN 51221, page 3.
Rate of pulling out the steel cord (pull out test):
100 mm/minute.
The force required to pull the steel cord out of the
test sample was measured and the average value of 10
measurements was determined.
The ten test readings and the average value in N/cm
have been listed in the Table hereafter.
Table 1
Vulcanizate containing:
preparation preparation preparation for comparison:
I II III mixture according
to the prior art
_ . _ . . ._ . . ._
390 360 340 3~0
390 380 340 350
-13-
~ 5~S~
320 380 350 350
400 390 3~0 30n
400 390 320 370
350 330 320 310
300 270 260 350
360 300 370 390
360 330 300 390
380 1 280 340 370
_ ~_
aver- 365 341 328 352
age
value
Slnce the results of this adhesion test (which is
close to actual conditions) show a fairly substantialy extent of
variation, it appears tha-t the vulcanizates from the rubber
mixtures containing the preparations according to the invention
have at leas-t equally good adhesive strengths as those according
to the prior art. Insofar as a trend is concerned -the adhesion
test with the preparation I shows the best values.
B) The following two rubber mixtures were produced from the
20 mixture ingredients listed hereafter and used for testing the
adhesion on textile fabrics. The amounts are in parts by weight.
The mixture no. 6 is the comparison mixture.
Ingredients Mixture No.
__
natural rubber ) 50 50
na-tural rubber 2) 50 50
stearic acid 3 3
poly-2,2,4-trimethyl-1,2-
dihydro quinoline 1
30 plasticizer oil, highly aromatic,
cold setting point ~ 0C. 7 7
GPF Black N 660 ) 27 30
granulated activated, precipitated
silica filler 3) +) 1 15 12
-14-
s~-~
zinc oxide 6 6
preparation no. I oE Example 1 6
mixture accoxding to ~he prior
art (see ~xample 1) + _ 6
benzothiazyl-2-cyclohexyl
sulphenamide 1
hexamethylene tetramine containing
3% of SiO2 +) 1.5 1.5
sulphur, insoluble 2.5 2.5
) Producer: Degussa, Postfach 2644
D 6000 Frankfurt/Main 1
GPF = General Purpose Furnace (Black)
) ribbed smoked sheets no. l;
60 Mooney L 4 (100C),
content of zinc pentachloro thiophenate 0.2%
brown crepe; 60 Mooney L 4 (100C);
content of zinc pentachloro thiophenate 0.2%
3) average primary particle size 18 ~Im;
specific surface area (DIN 66132) 175 sq.
m/g (Ultrasil ~ VN3 of Degussa)
The two rubber mixtures were then vulcanized, in
each case together with or on a fabric of polyethylene glycol
teraphthalate (Trevira ~ EP) having a square metre weight of
550 g and consisting of threads having a strength (measured
in dtex) of lOG x 3 in the warp and 940 x 3 in the wef~ and a
thread number of 116 per 10 cm in the warp and 45 per 10 cm
in the weft, in a press at a pressure of 1.4 kN per sq cm
and the bond was tested for adhesion (textile adhesion test
according -to DIN 53530). The fabric used was nei-ther impregnated
nor treated.
In each case the separating force required to pull
the fabric layer from the rubber test strip of 2.5 cm width
was measured. The pull-test machine defined in DIN 51221, page
-15-
3 was used. Minimum and maxirnum values of the force readings
in the individual phases of t}le separation of the fabric from
the rubber were measured in N and the following values were
obtained:
Table 2
Vulcanizate containing:
preparation I for comparison:
(from mixture 5) mixture according
to the prior art
(from mixture 6)
1. 200 3 270 180 ~ 240
2. 220 J 300 180 ~ - ~ 260
It is evident from the test results that the adhesive
strengths of the fabrics on rubber show favourable values and
that they are superior to those according to the prior artO
Altogether, it is evident from the examples that the
preparations according to the invention result in a distinct
advance in the art as compared with the prior art. This is
borne out by the improved fluidity and dosability of the products
according to the invention and by the fact that they do not form
dust. The reduced sublimation tendency is a further important
advantage. In the adhesive effect and in the rubber~technological
properties at least rends towards better test values can be
detected. In this respect the preferred embodiment of the
preser.t invention (preparation I according to Example 1) must
also be regarded as an advance in the art as compared with the
prior art.
The preparations according to the invnetion are used
in rubber mixtures for producing all kinds of vehicle tires,
particularly pneumatictires, for retreading tires, for producing
conveyor belts, technical hoses, as for example, fire hoses and
compressed-air hoses, as well as rubberized fabrics, containers,
shoes, camping articles, boats, V-belts and other moulded articles,
-16-
all of which are composite articles of rubber and the inser-ts
or coatings mentioned hereinbefore.
-17-
