Title of Invention

A PROCESS FOR THE PRODUCTION OF FINELY DIVIDED, PULVERULENT RUBBER POWDER

Abstract This invention relates to pulverulent rubbers containing filler which remain free-flowing even after exposure to mechanical stresses and to a process for the production thereof, in which the rubber powder is obtained in two precipitation steps, and to the use of these powders for the production of vulcanisable rubber compounds.
Full Text lA
Pulverulent rubber powder containing filler, process for the production thereof and use thereof
This invention relates to pulverulent rubbers containing fillers, to a process for the production thereof and to the use thereof.
Numerous publications have appeared relating to the aim and purpose of using powdered rubbers as well as to possible processes for the production thereof.
The explanation for the interest in pulverulent rubbers is readily evident from the processing techniques used in the rubber industry, where rubber compounds are produced in time-consuming processes with elevated inputs of energy and labour. The principal reason for this is that the rubber raw material is in bale form.
Comminuting the bale, intimate mixing with fillers, mineral oil plasticisers and vulcanisation auxiliaries proceeds in roll mills or in internal mixers in two or more processing stages. The compound is generally stored between the stages. Downstream from the internal mixers or roll mills are extruder/pelletisers or extruder/roller dies. The only way out of this highly complex rubber processing method is to use an entirely novel processing technology. The use of free-flowing rubber powders has accordingly long been discussed as such powders would make it possible to process rubber compounds simply and rapidly in the same manner as pulverulent thermoplastics.
DE-PS 2822 148 discloses a process for the production of a pulverulent rubber containing fillers.
According to this patent, an aqueous filler emulsion is added to a rubber latex, rubber solution or an aqueous emulsion of a rubber and the desired rubber powder is precipitated.


Variants for preventing the resultant filler contents being
determined by grain size, as occurs when this process is
used, have been filed and, as DE-PS 3723 213 and DE-PS 3723
214, are part of the prior art.
According to DE-PS 3723213, in a two-stage process, a
quantity of >50% of the filler is initially incorporated
into the rubber powder particles. In the second stage, the
remainder of the filler is applied onto the so-called basic
rubber grains.
This may be considered a variant of dusting as no bond is
created between the filler and rubber.
However, as E.T. Italiaander has pointed out (presentation 151, technical conference of the Rubber Division of the ACS, Anaheim, California, 6-9 May 1997 (GAK 6/1997 (50) 456-464), despite the bright future predicted in the Delphi Report (Delphi Report, "Kunftige Herstellverfahren in der Gummiindustrie", Rubber Journal, volume 154, no. 11, 20-34 (1972)) for pulverulent and pelletised rubbers and numerous attempts made by well-known polymer manufacturers from the mid 1970's until the early 1980's to produce pulverulent NBR, SBR/carbon black masterbatches and pelletised NR, the rubber bale remains the standard form in which polymers are supplied.
One disadvantage of known processes is firstly that a grinding operation is necessary in order to achieve a grain diameter of the filler particles of 10 m, which is considered essential to the quality of the final product.
However, this requires not only elevated energy input but also results in damage to the filler structure which, together with the active surface area, is a significant parameter for its effectiveness in rubber applications.
Secondly, the handling properties of prior art products suffer in that the particles stick together during storage.

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The object of the invention is accordingly to provide a pulverulent rubber containing filler which is easily handled, together with a process for the production thereof.
The present invention provides a pulverulent rubber (rubber powder) having a filler content solidly bonded to the rubber matrix by the precipitation process. No confusion is thus possible with only superficially (adhesively) coated rubber particles (keyword: dusting, surface precipitation (sic)) .
The powders according to the invention exhibit a narrow
size distribution which is shifted towards smaller particle
sizes as is known from the prior art
(Kautschuk + Gummi + Kunststoffe 7, 28 (1975) 397-402) .
This fact facilitates processing of the powders.
Moreover, due to the production process, the filler content
of the individual particles is not determined by grain
size.
The pulverulent rubbers contain from 20 to 250 phr, in
particular from 50 to 100 phr, of filler (phr: parts per
hundred parts of rubber).
The following, individually or as mixtures, have proved to
be suitable types of rubber:
natural rubber, emulsion SBR having a styrene fraction of
10 to 50%, butyl/acrylonitrile rubber,
butyl rubbers, terpolymers prepared from ethylene,
propylene (EPM) and unconjugated dienes (EPDM), butadiene
rubbers, SBR, produced using the solution polymerisation
process, having styrene contents of 10 to 25%, as well as
1,2-vinyl constituent contents of 20 to 55% and isoprene
rubbers, in particular 3,4-polyisoprene.
In addition to the stated rubbers, the following elastomers may be considered, individually or as mixtures:
carboxyl rubbers, epoxy rubbers, trans-polypentenamer, halogenated butyl rubbers, rubbers prepared from

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2-chlorobutadiene, ethylene/vinyl acetate copolymers, epichlorohydrins, optionally also chemically modified natural rubber, such as for example epoxidised grades. Fillers which may be mentioned are the carbon blacks known from rubber processing and white fillers of a synthetic nature, such as for example precipitated silicas or natural fillers, such as for example siliceous chalk, clays etc..
Carbon blacks, as are generally used in rubber processing, are particularly suitable.
Such carbon blacks include furnace blacks, gas blacks and
lamp backs having an iodine absorption value of 5 to
1000 m2/g, a CTAB value of 15 to 600 m2/g, a DBP adsorption
of 30 to 400 ml/100 g and a 24 M4 DBP value of 50 to
370 ml/100 g in a quantity of 5 to 250 parts, in particular
of 20 to 150 parts, per 100 parts of rubber, in particular
of 40 to 100 parts.
Precipitated silicas known from the rubber sector are also suitable.
These generally have an N2 surface area, determined using the known BET method, of 35 to 700 m2/g, a CTAB surface area of 30 to 500 m2/g, a DBP value of 150 to 400 ml/100 g. The product according to the invention contains these silicas in a quantity of 5 to 250 parts, in particular of 20 to 100 parts, relative to 100 parts of rubber.
If white natural fillers are used, such as clays or siliceous chalks having an N2 surface area of 2 to 35 m /g, they are used in a quantity of 5 to 350 parts, relative to 100 parts of rubber.
Filled rubber powders, which contain a mixture of silicas and carbon black are also suitable.
In this case, the total quantity of filler amounts to 20 to 250 parts of filler per 100 parts of rubber.

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Apart from the above-stated fillers, the rubber powders
according to the invention optionally contain known
processing or vulcanisation auxiliaries such as zinc oxide,
zinc stearate, stearic acid, polyalcohols, polyamines,
plasticisers, anti-ageing agents to counter the action of
heat, light or oxygen and ozone,
reinforcing resins, flame retardants, such as for example
A1(OH)3 and Mg(OH)2, pigments,
various crosslinking chemicals and optionally sulfur in
concentrations conventional in rubber processing.
The cross-section of the rubber powders according to the invention differs distinctly from that of products known from the prior art.
While these latter products ideally exhibit a homogeneous distribution of the filler in the rubber composition or vice versa and have a shell of filler particles, according to the invention there is a homogeneous distribution of filler and rubber component within the pulverulent products and in the associated peripheral zone.
Depending upon the filler loading of the particles, filler particles are incorporated into the surface, such that the particles do not stick together, even under pressure, such as when several sacks are stacked.
This "inertisation" of the surface should not be confused with the known technique of dusting tacky powders with fillers. These only superficially adhering fillers are rapidly detached when exposed to mechanical stress, for example in conveying plant or on transfer into silos. The sticking and agglomeration of the finely divided powders, which it is the intention to avoid, then occurs despite the dusting.
Unlike the tacky particles superficially coated with fillers as flow auxiliaries as are known from the prior art, according to the invention, filler particles are incorporated into the surface during the precipitation process for the production of the pulverulent rubber.

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Depending upon the filler loading with one or more of the above-stated fillers, the advisable distribution between the interior of the particles and an outer zone associated therewith is established.
In a product having an elevated filler loading (>80 parts of filler per hundred parts of rubber), only 1 to 10 parts of this quantity of filler are incorporated in the outer grain zone.
However, if the pulverulent rubber contains a total of The distributions of the filler within the particles and in the so-called peripheral zone generally vary between these contents.
The greater is the total filler content, the less is the need to suppress the tackiness of the powder by an increased concentration of filler in the peripheral zone.
The present invention also provides a process for the production of finely divided, pulverulent rubbers containing filler (rubber powders) by precipitation from mixtures containing water which contain filler in the form of suspensions, water-soluble salts of a metal of groups IIa, lIb, IIIa and VIII of the periodic system of elements and a rubber latex or aqueous emulsions of a rubber solution by addition of an acid, which process is characterised in that >50 wt.% of the finely divided filler are mixed with 0.1 to 6.5 parts by weight per 100 parts by weight of rubber of the stated water-soluble salts and a rubber latex or an aqueous emulsion of a rubber solution, the pH value of the mixture is reduced to a value in the range from 5.5 to 4.5 {first stage), the remainder of the finely divided filler in the form of a suspension is added and the pH value is reduced to approx. 3.2 (second stage),

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such that the rubber in the mixture is completely-precipitated together with the filler.
The duration of the precipitation operation, which is determined by the pH value and the filler content, and the extent thereof may readily be determined by means of a series of measurements.
In the case of a powder rubber having an elevated filler loading (>80 parts of filler phr), 1 to 10 parts of this quantity will generally be used as the remaining proportion in the second stage on precipitation of the powder rubber.
If the powder rubber contains less than 80 parts of filler phr, for example a total of only 50 parts phr, >10 to 2 0 parts of this quantity will be introduced into the mixture in the form of a suspension before conclusion of the precipitation operation.
In this manner, the fillers are incorporated into the outer grain zone (peripheral zone) of the rubber powder.
These proportions of the filler are thus not applied externally onto the individual rubber particles {c.f. DE-PS 37 23213), but are integrated into the surface of the rubber.
This distribution of the filler and the manner in which the fillers are bonded to the rubber composition bring about the elevated flowability of the powders according to the invention and prevent sticking during storage of the powder, without these properties being lost on exposure to mechanical stresses during conveying, transfer into silos etc.
The above-stated carbon blacks are used as fillers in finely divided (fluffy) form, the carbon blacks generally having an average grain diameter of 1 to 9 m, preferably of 1 to 8 m, before they are suspended.

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This facilitates dispersion, such that aqueous suspensions containing filler particles of an average particle diameter of distinctly less than 10 m are obtained without elevated energy input.
Precipitated silica may advantageously be used in the form of a filter cake which has been washed until salt-free.
Metal salts which may be considered are those originating
from elements of groups IIa, IIb, IIIa and VIII of the
periodic system of elements. This division into groups
corresponds to the former IUPAC recommendation
(Periodisches System der Elemente, Verlag Chemie, Weinheim,
1985)
Typical representatives are magnesium chloride, zinc
sulfate, aluminium chloride, aluminium sulfate, iron
chloride, iron sulfate, cobalt nitrate and nickel sulfate,
wherein the salts of aluminium are preferred. Aluminium
sulfate is particularly preferred.
The salts are used in a quantity of 0.1 to 6.5 parts by
weight per 100 parts by weight of rubber. Acids suitable
and optionally used to establish the defined pH values are
primarily mineral acids, such as for example sulfuric acid,
phosphoric acid and hydrochloric acid, wherein sulfuric
acid is particularly preferred. However, carboxylic acids,
such as for example formic and acetic acid, may also be
used.
The quantity of acid is determined by the nature and quantity of the water-soluble metal salt, the filler, the rubber and the optionally present alkali metal silicate. This quantity may readily be determined by initial investigatory testing.
According to a preferred embodiment of the process according to the invention, up to 5 parts by weight per 100 parts by weight of rubber of silica (SiO2) are additionally used in the form of an alkali metal silicate solution, preferably as water glass having an Na2O:SiO2 molar ratio of 2:1 to 1:4. The alkali metal silicate solution may here

9
be added both to the rubber component and to the filler suspension. It is preferably added to the rubber component, especially when the process is performed continuously.
The process according to the invention is generally performed as follows:
first of all, a filler suspension is produced by dispersing a proportion, preferably >50%, of the filler present in the final product in water together with the metal salt and optionally the alkali metal silicate solution. The overall quantity of water is determined by the nature of the filler and the degree of digestion. In general, the water insoluble constituents of the filler amount to approx. 6 wt.%. This value is not a binding restriction and both lower and higher quantities may be encountered. The maximum content is limited by the pumpability of the suspension.
The filler suspension produced in this manner is then intimately mixed, preferably in the presence of an emulsifier, with the rubber latex optionally containing alkali metal silicate solution or the aqueous emulsion of a rubber solution optionally containing alkali metal silicate solution. Known stirrers, such as for example propeller stirrers, are suitable for this purpose.
After mixing, a pH value in the range from 5.5 to 4.5 is first established while stirring is continued. This results in basic rubber grains having a constant filler content. The size of these basic grains is controlled by the selected quantity of metal salt in the range from 0.1 to 6.5 phr. Control is effected by the largest grain size being obtained with the lowest quantity of metal salt.
The solids content of the latex used generally amounts to 20 to 25 wt.%. The solids content of the rubber solutions is generally 3 to 35 wt.%, that of the rubber emulsions generally from 5 to 30 wt.%.

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These mixtures and the production thereof are known from the prior art.
When working up rubber powders having filler contents of >100 phr, it is advantageous to reduce the pH value down to 2.5 before phase separation. An acid from the above-stated group of acids is advantageously used for this purpose.
The process according to the invention may be performed both discontinuously and continuously.
The precipitated rubber powder is advantageously separated by means of a centrifuge and then dried to a residual water content of generally During the production process, further processing and/or vulcanisation auxiliaries may be added to the rubber powder according to the invention in a quantity conventional for vulcanisable rubber compounds or also a smaller quantity.
The rubber powders according to the invention are used for
the production of vulcanisable rubber compounds.
The constituents necessary for producing the compound may
all be present in the rubber powder.
Preferably, however, the powders contain rubber of the
above-stated types and fillers.
They may, however, also be mixed in a conventional manner
with other rubbers and fillers, if this is necessary for
the desired rubber compound.
It is possible according to the invention to produce a finely divided rubber powder which is free-flowing and also remains free-flowing after exposure to mechanical stresses (for example conveying, packaging).
By virtue of the finely divided nature thereof, no grinding or other comminution measures are required to obtain finely divided dispersions.

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These then give rise to the finely divided rubber powders, which may readily be processed, and to vulcanisates having improved properties.

13
6PPD N-l,3-diraethylbutyl-N'-phenyl-p-
phenylenediamine
CBS N-cyclohexyl-2-benzothiazolesulfenamide

12 Examples
A. The Examples describe the processing behaviour of
rubber powders produced according to the prior art
(DE-PS 3723213) and the rubber powders according to the
invention.
The technical rubber data obtained with these powders are also compared.
In Example 1, compounds 1 to 4 are produced using an N 375 carbon black in the only form in which it is generally available, namely in wet-beaded form. In order to achieve the fineness required according to DE-PS 3723213 of 10 m (average grain diameter) , it had to be ground beforehand. This corresponds to the situation at the time of filing of the stated patent. Compounds 5 to 8 are produced using N 375 in "fluffy" form.
It has been found that the vulcanisate produced using the rubber powders according to the invention give rise to superior technical rubber data with shorter compounding times for the rubber compounds and identical compositions of the compounds.
B. Test standards used in the Examples:
Unit Standard
Tensile strength Mpa DIN 53504
Modulus, 300% Mpa DIN 53504
Tear propagation
resistance N/mm DIN 53507
Shore A hardness - DIN 53507
DIN abrasion nm3 (sic) DIN 53516
Elongation at break % DIN 53504
C. Chemicals used in the Examples:
TESPT bis(triethoxysilylpropyl)tetrasulfane (Si69, Degussa AG
Naftolen ZD plasticiser, aromatic hydrocarbons

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Example 1 Comparison of an emulsion SBR compound filled with N 375 (82 parts) as a function of compounding time (standard process in comparison with process according to the invention)
a) Formulations 1-4 5-8
PB I (standard) 180
EPB I (according to the invention) - 180
ZnO RS 3 3
Stearic acid 2 2
Naftolen ZD 30 30
6PPD 2 2
Wax 1 1
CBS 1.35 1.35
Sulfur 1.35 1.35

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b) Compounding process

1st stage

Internal mixer: GK 1.5 N, volume 1.6 L, friction 1:1.11, plunger
pressure 5.5 bar
Compound 1-8
PRM (sic) [l/min] 60
Temp. [°C] 50
Filler loading 0.85
Compounding time:
0-0.5' PB I or EPB I
Naftolen ZD, ZnO RS, stearic acid.
6PPD, wax
0.5' cleaning and venting
0.5'-x' compounding and discharge
X' = 1, 2, 3, 4
Batch temperature: -150°C

16

2nd stage

Internal mixer: RPM 4 0 GK 1.5 N, volume 1.6 L, friction 1 pressure 5.5 bar , temperature 50°C, filler loading : 1.11, plunger 0.68
Compounding time:
0-0.5' batch, stage accelerator, 1 sulfur
0.5'-1.5' compounding, discharge & sheeting out
Batch temperature: - 110°C
c) Vulcanisate testing
1. Filler dispersion, particle size, polydispersity

Standard Process according to the
invention
Compounding time 4 3 2 1 4 3 2 1
[min]
Dispersion 96.5 95.7 95.4 93.5 95.4 95.6 95.2 93.4
coefficient [%]
lst moment ( m) 13.0 17.6 16.3 16.5 11.4 10.8 12.3 12.1
(sic)
2nd moment ( m) 21.7 28.9 28.9 27.7 15.8 13.5 17.9 16.8
(sic)
3rd moment ( m) 36.4 40.5 40.7 41.5 27.6 19.6 30.2 26.4
(sic)
Polydispersity 0.67 0.64 0.65 0.68 0.38 0.25 0.46 0.39
The comparison shows that, using the process according to the invention, particle sizes (moments 1-3) are distinctly-smaller than in the case of the standard process and that

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furthermore the particles are also more uniform (lower value for polydispersity).
2. Technical rubber data

Standard Process according to the
invention
Compounding time 4 3 2 1 4 3 2 1
[min]
Test method:
Tensile strength 15.9 15.8 15.1 15.0 16.4 16.7 16.4 16.4
[MPa]
Modulus, 3 00% 6.8 7.1 6.8 7.0 7.3 7.5 7.3 7.4
[MPa]
Elongation at 600 570 560 550 590 590 590 600
break [%]
Fracture energy 145 135 127 124 14 7 149 148 155
[J]
Shore A hardness 64 63 65 65 64 63 64 65
Ball rebound: %
0°C 18.7 18.1 17.9 18.1 18.4 18.3 18.2 18.4
60°C 35.1 34.8 34.3 33.9 37.5 36.8 37.1 36.3
Loss anqle:
tan 5 (0°C) 0.374 0.373 0.368 0 .368 0.381 0.374 0.359 0.365
tan 8 (60°C) 0.311 0.304 0.318 0.311 0 .298 0.299 0.302 0.300
The comparison shows that even at the shortest compounding time (1'), the products according to the claimed process

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provide excellent properties. The advantages are particularly distinct with regard to strength values, fracture energy and greater elongation at break. There are also advantages with regard to rebound and tan at 60°C.

19
Example 2 Comparison of an emulsion SBR based car tread
compound filled with silica/TESPT (standard
process in comparison with process according to
the invention)
a) Formulations 1 2
PB II (standard) 175
EPB II (according to the invention) - 175
ZnO RS 3 3
Stearic acid 2 2
Naftolen ZD 10 10
6PPD 2 2
Wax 1 1
CBS 1.5 1.5
DPG 2 2
Sulfur 1.5 1.5

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b) Compounding process
1 stage

Internal mixer: GK 1.5 N, volume 1.6 L, friction 1:1.11, plunger
pressure 5.5 bar
Compound 1 & 2
PRM (sic) [1/min] 60
Temp. [°C] 50
Filler loading 0.8
Compounding time:
0-3' PB II or EPB II
Naftolen ZD, ZnO RS, stearic acid,
6PPD, wax
3 ' cleaning and venting
3' -4' compounding and discharge
Batch temperature: -155°C

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2 stage

Internal mixer: RPM 4 0 GK 1.5 N, volume 1.6 L, friction 1 pressure 5.5 bar , temperature 50°C, filler loading :1.11, plunger 0.68
Compounding 0-0.5'
0.5'-1.5 ' time: batch, stage accelerator,
compounding, 1 sulfur
discharge & sheeting out
Batch temperature: ~ 110°C
c) Technical rubber data

Test method Unit 1 2
Dispersion Roughness factor 3025 960
Tensile strength MPa 20.2 22.7
Modulus, 300% MPa 12.9 13.7
Elongation at break % 410 440
Fracture energy- J 12 6 143
Shore A hardness - 78 77
DIN abrasion mm3 90 80
The products of the process according to the invention are distinguished by better dispersion, greater strength, greater reinforcing behaviour and better DIN abrasion.

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WE CLAIM:
1. A process for the production of finely divided, pulverulent rubber powder
containing filler, comprising:
a) mixing > 50 wt. % of a filler with:
i. 0.1 to 6.5 parts by weight of water-soluble salts per 100
parts by weight of rubber, and ii. a rubber latex or an acqueous emulsion of a rubber solution.
b) reducing the pH value of the mixture formed in step a) to a value in
the range from 5.5 to 4.5,
c) adding the remainder of the filler as a filler suspension, and
d) reducing the pH value to approximately 3.2 causing the
precipitation of the rubber and the filler,
wherein the filler suspension comprises water-soluble salts of a metal selected from group IIa, lIb, IlIa or VIII of the periodic table of elements.
2. The process according to claim 1, wherein the filler comprises a total
content of > 80 parts phr of filler, 1 to 10 parts phr of this quantity are added as
the remainder.
3. The process according to claim 2, wherein the filler comprises a total
content of > 80 parts phr of filler, > 10 to 20 parts phr of this quantity are added
as the remainder.
4. The process according to claim 1, further comprising:
Adding carbon black having an average grain size of 1 to 9 m.

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5. The process according to claim 1, comprising:
adding silica in the form of a filter cake which has been washed until salt-free.
6. The process according to claim 1, further comprising:
adding processing and/or vulcanization additives during the precipitation.
7. The process according to claim 1, wherein the water-soluble salts
comprise aluminum sulfate.
8. The process according to claim 1, comprising:
performing the process in the presence of alkali metal silicate.
9. The process according to claim 8, comprising:
adding up to 5 phr of SiO2 in the form of an alkali metal silicate solution.
10. The process according to claim 1, comprising reducing the pH value to 2.5
before phase separation.
11. The process according to claim 1, comprising:
adding the pulverulent rubber powder to a mix for a vulcanizate.
This invention relates to pulverulent rubbers containing filler which remain free-flowing even after exposure to mechanical stresses and to a process for the production thereof, in which the rubber powder is obtained in two precipitation steps, and to the use of these powders for the production of vulcanisable rubber compounds.

Documents:

00315-cal-1999-abstract.pdf

00315-cal-1999-claims.pdf

00315-cal-1999-correspondence.pdf

00315-cal-1999-description(complete).pdf

00315-cal-1999-form-1.pdf

00315-cal-1999-form-18.pdf

00315-cal-1999-form-2.pdf

00315-cal-1999-form-3.pdf

00315-cal-1999-form-5.pdf

00315-cal-1999-g.p.a.pdf

00315-cal-1999-letters patent.pdf

00315-cal-1999-priority document others.pdf

00315-cal-1999-priority document.pdf

315-CAL-1999-CORRESPONDENCE 1.1.pdf

315-CAL-1999-CORRESPONDENCE-1.1.pdf

315-CAL-1999-FOR ALTERATION OF ENTRY.pdf

315-CAL-1999-FORM 27-1.1.pdf

315-CAL-1999-FORM 27.pdf

315-CAL-1999-FORM-27.pdf

315-CAL-1999-PA.pdf


Patent Number 203274
Indian Patent Application Number 315/CAL/1999
PG Journal Number 10/2007
Publication Date 09-Mar-2007
Grant Date 09-Mar-2007
Date of Filing 06-Apr-1999
Name of Patentee PKU PULVERKAUTSCHUK UNION GMBH.
Applicant Address PAUL-BAUMANN-STRASSE 1, GERMANY, DE-45764 MARL
Inventors:
# Inventor's Name Inventor's Address
1 DR. UDO GORL HERDERSTRASSE 38, DE-53332 BORNHEIM
2 DR. REINHARD STOBER BORNWIESENWEG 22, DE-63594 HASSELROTH
3 HARTMUT LAUER ECKARDROTHER STRASSE 2, DE-63628 BAD SODEN-SALMUNSTER
4 UWE ERNST BITTERFELDER STRASSE 7A, DE-45772 MARL
PCT International Classification Number C 08 K 3/10
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 19815453.4 1998-04-07 Germany