ISO/TC 45/SC 3/WG 3 - Carbon black, silica and rubber chemicals

This document specifies the test methods to be used for magnesium oxide intended for use in the rubber industry as a stabilizer and vulcanizing agent. The choice of the properties to be determined and the values required are subject to agreement between the interested parties.

This document specifies two methods for the determination of the total sulfur in all types of carbon black for use in the rubber industry: — Method A, using a combustion furnace; — Method B, using an automatic analyser. With respect to safety aspects and test precision, it is preferable to use automatic systems. Method B is therefore the preferred method. Classical chemical analysis (Method A) is acceptable if automatic equipment is not available.

This document specifies two methods for the determination of the specific surface area of types and grades of carbon black for use in the rubber industry: — method A: automatic gas chromatography method (carrier gas method); — method B: automatic volumetric method. Somewhat different results might be obtained from the two methods. The degassing procedure differs between method A and method B, and it is important to investigate the possibility of correcting the results by using standard reference blacks. The results might also differ from those obtained using the multipoint method specified in ISO 18852, which is the preferred method. These methods are not applicable to porous carbon blacks.

This document specifies a general method for determining the aggregate size distribution (ASD) of silica by using a disc centrifuge according to the principle of sedimentation. As pre-stage the silica is de-agglomerated in water using strong ultrasonic power treatment. The method is used for precipitated silica.

This document specifies a method for the determination of the light transmittance of the toluene extract from carbon black for use in the rubber industry, as a means of measuring the discolouration caused by the extractable matter. The light transmittance value provides an estimate of the degree of discolouration caused by the toluene-extractable matter present on the surface of the carbon black. This method might not be applicable to carbon blacks with a high extractable-matter content.

This document specifies sampling and test methods for the determination of the general characteristics of organic chemicals such as accelerators, antidegradants (including wax) and vulcanizing agents (excluding peroxides).

ISO 5435:2017 specifies a method for the determination of the tinting strength of carbon black relative to an industry tint reference black. The method is based on the use of five different commercial instruments. Other instruments can be used if the test results for the standard reference blacks are within the control limits given in ASTM D4821. NOTE The Densichron reflectometer and the Meeco Colormaster are no longer commercially available, but the procedures have been included for the benefit of those who still use these instruments.

ISO 11236:2017 applies to a variety of substituted p-phenylenediamine antidegradants (PPDs) used in the rubber industry. The three general classes of PPDs are dialkyl, alkyl-aryl and diaryl, which are used to impart ozone resistance to rubber. The following test methods are of greatest significance in assessing the purity of production PPDs, and hence their suitability for use in rubber. They are specified in this document as follows: - determination of purity by gas chromatography (GC); - determination of purity by high-performance liquid chromatography (HPLC); - determination of ash; - determination of volatile matter.

ISO 9298:2017 specifies the methods to be used for the evaluation of zinc oxide for use in the rubber industry. The analytical methods are applicable to all commercial zinc oxides, for example: - direct type (American process); - indirect type (French process); - other types produced by different chemical methods, i.e. precipitation and calcination. Zinc oxide can also be coated with organic materials, such as fatty acids, oil, wetting agents, etc., in order to improve the dispersion in rubber.

ISO 15825:2017 specifies a method for determining the size distribution of carbon black aggregates, using a disc centrifuge photosedimentometer. This technique is based on the hydrodynamic behaviour of carbon black in a centrifugal field. The determination of the aggregate size distribution is important in the evaluation of carbon black used in the rubber industry.

ISO 1437:2017 specifies a method for determining the water-wash sieve residue from regular, untreated carbon black for the rubber industry. It may not be applicable to oil-treated blacks because the oil could prevent proper wetting of the black by water.

ISO 1304:2016 specifies methods for the determination of iodine adsorption number of carbon blacks for use in the rubber industry. Two titration methods are described: - method A: titration using a burette and starch as indicator; - method B: potentiometric titration with an automatic titrator. The iodine adsorption number is related to the surface area of a carbon black and is generally in agreement with the nitrogen surface area. However, it is significantly depressed in the presence of a high content of volatile or solvent-extractable materials; the iodine adsorption number therefore does not always provide a measure of the specific surface area of a carbon black. Ageing of carbon black can also influence the iodine number. In case of dispute, the preferred method is method B (potentiometric titration).

ISO 19246:2016 specifies a general method for determining the liquid absorption capacity of a pigment and extender by using di-(2-ethylhexyl) adipate (DOA, CAS 103-23-1). The determination of the DOA absorption number is performed by means of an absorptometer which is equipped with a torque measurement and processing system. The DOA absorption number provides an indication of the void volume formed by the aggregates and agglomerates of the pigments and extenders.

ISO 1126:2015 specifies methods for determining the loss on heating of carbon black for use in the rubber industry. This loss on heating is due primarily to loss of moisture, but traces of other volatile materials may also be lost. These methods are not applicable to treated carbon blacks which contain added volatile materials. One of the following three methods is used: - method 1: gravity-convection oven method; - method 2: moisture balance method; - method 3: infrared irradiation method (rapid method). Method 1 is the preferred method.

ISO 1125:2015 specifies a method for determining the ash of all types of carbon black for use in the rubber industry.

ISO 18852:2015 specifies a method for the determination of the nitrogen surface area (NSA) of carbon blacks and other rubber compounding ingredients, like silicas and zinc oxides, based on the Brunauer, Emmett and Teller (BET) theory of gas adsorption using a multipoint determination as well as the determination of the statistical thickness surface area (STSA), otherwise known as the external surface area. STSA, however, is not applicable to silica and zinc oxide. The method can also be used for verifying "single-point" procedures described in ISO 4652 and other standards.

Oil absorption number (OAN) is a measure of the ability of a carbon black to absorb liquids. This property is a function of the structure of the carbon black. Either dibutyl phthalate (DBP) or paraffin oil is acceptable for use with standard pelleted grades, including N‑series carbon blacks found in ASTM D1765, although OAN testing using paraffin oil on some speciality blacks and powder blacks might result in unacceptable differences as compared to OAN testing using DBP oil. While studies have shown the two oils to give comparable precision, paraffin oil offers the advantage of being non-hazardous. ISO 4656:2012 specifies a method using an absorptometer for the determination of the oil absorption number of carbon black for use in the rubber industry. The same method is used for the determination of the oil absorption number of compressed samples of carbon black. The procedure for the preparation of the compressed samples is described in an annex.

Carbon black for the rubber industry is generally pelletized to reduce dust and to improve handling and incorporation into polymers. Variations in pellet size distribution can affect dispersion in polymers, bulk handling, and conveying properties. ISO 8511:2011 specifies a method for the determination of the pellet size distribution of carbon black.

ISO 8942:2010 specifies two methods for the determination of the individual pellet crushing strength of carbon black for use in the rubber industry: method A: using pellets of size ranging from 1,4 mm to 1,7 mm; method B: using pellets of size 1 mm.

ISO 6209:2009 specifies a method for the quantitative determination of the solvent-extractable material in carbon black for use in the rubber industry. The method is applicable to all types of carbon black.

Describes a method for the determination of the fraction of a test portion of pelletized carbon black used in rubber industry that will pass through a sieve with 125 m nominal aperture size under specified conditions. Replaces the third edition.

Specifies a method for the determination of the dust content of pelletized carbon blacks. Permits a differentiation to be made between micro-pellets and dust and is applicable to all pelletized carbon blacks for the rubber industry.

Gives a method for the determination of the pour density of all types of pelletized carbonblacks for use in the rubber industry. Replaces the third edition which has been technically revised.

Specifies procedures for the sampling of carbon black for use in the rubber industry, delivered in bulk, semi-bulk or packages.

ISO 15825:2015 specifies a method for determining the size distribution of carbon black aggregates, using a disc centrifuge photosedimentometer. This technique is based on the hydrodynamic behaviour of carbon black in a centrifugal field. The determination of the aggregate size distribution is important in the evaluation of carbon black used in the rubber industry.

This International Standard specifies four methods for the determination of the specific surface area of types and grades of carbon black for use in the rubber industry: — method A using the Ni‑Count‑1 apparatus (Clause 3); — method B using the Areameter apparatus (Clause 4); — method C using gas chromatography (Clause 5); — method D using the Monosorb surface-area analyser (Clause 6). Somewhat different results might be obtained from the four methods. The degassing procedure used differs from method to method, and it is important to investigate the possibility of correcting the results by using standard reference blacks. The results might also differ from those obtained using the multipoint method specified in ISO 18852, which is the preferred method.

ISO/TS 16176:2011 specifies a method for determining the size distribution of carbon black aggregates dispersed in a liquid by means of a high-power ultrasonic device. The measurement is done with a disc centrifuge photosedimentometer. This technique is based on the hydrodynamic behaviour of carbon black in a centrifugal field. The determination of the aggregate-size distribution is important in the evaluation of carbon black used in the rubber industry.

ISO 5435:2008 specifies a method for the determination of the tinting strength of carbon black relative to an industry tint reference black. The method is based on the use of five different commercial instruments. Other instruments may be used if the test results for the standard reference blacks are within the control limits given in ASTM D 4821. NOTE The Densichron reflectometer and the Meeco Colormaster are no longer commercially available, but the methods have been included for the benefit of those who still use these instruments.

ISO 3858:2008 specifies a method for the determination of the light transmittance of the toluene extract from carbon black for use in the rubber industry, as a means of measuring the discolouration caused by the extractable matter. The light transmittance value provides an estimate of the degree of discolouration caused by the toluene-extractable matter present on the surface of the carbon black. This method may not be applicable to carbon blacks with a high extractable-matter content.

Oil absorption number (OAN) is a measure of the ability of a carbon black to absorb liquids. This property is a function of the structure of the carbon black. Either dibutyl phthalate (DBP) or paraffin oil is acceptable for use with standard pelleted grades, including N-series carbon blacks found in ASTM D 1765, although OAN testing using paraffin oil on some speciality blacks and powder blacks may result in unacceptable differences as compared to OAN testing using DBP oil. While studies have shown the two oils to give comparable precision, paraffin oil offers the advantage of being non-hazardous. ISO 4656:2007 specifies a method using an absorptometer for the determination of the oil absorption number of carbon black for use in the rubber industry. The same method is used for the determination of the oil absorption number of compressed samples of carbon black. The procedure for the preparation of the compressed samples is described in the standard.

ISO 1437:2007 specifies a method for determining the water-wash sieve residue from regular, untreated carbon black for the rubber industry. It may not be applicable to oil-treated blacks because the oil could prevent proper wetting of the black by water.

ISO 1138:2007 specifies three methods for the determination of the total sulfur in all types of carbon black for use in the rubber industry: Method A, using an oxygen bomb calorimeter; Method B, using a combustion furnace; Method C, using an automatic analyser. With respect to safety aspects and test precision, it is preferable to use automatic systems. Classical chemical analysis (Method A and Method B) is acceptable if automatic equipment is not available.

ISO 1126:2006 specifies methods for determining the loss on heating of carbon black for use in the rubber industry. This loss on heating is due primarily to loss of moisture, but traces of other volatile materials may also be lost. The methods are not applicable to treated carbon blacks which contain added volatile materials. The following methods are described: method 1: gravity-convection oven method; method 2: moisture balance method; method 3: infrared irradiation method (rapid method).

ISO 1304:2006 specifies methods for the determination of iodine adsorption number of carbon blacks for use in the rubber industry. Two titration methods are described: method A: titration using a burette and starch as indicator; method B: potentiometric titration with an automatic titrator.

ISO 18852:2005 specifies a method for the determination of the nitrogen surface area (NSA) of carbon blacks and other rubber compounding ingredients, like silicas and zinc oxides, based on the Brunauer, Emmett and Teller (BET) theory of gas adsorption using a multipoint determination. This test method specifies the sample preparation and treatment, instrument calibration, required accuracy and precision of the experimental data, and calculation of the surface area results from the data obtained. Also given is a procedure for calculating the statistical thickness surface area (STSA), otherwise known as the external surface area. The test method specified uses an automatic volumetric static-vacuum apparatus, the surface area being calculated using the BET theory based on monolayer measurements.

ISO 3858:2004 specifies a method for the determination of the light transmittance of the toluene extract from carbon black for use in the rubber industry, as a means of measuring the discolouration caused by the extractable matter. The light transmittance value provides an estimate of the degree of discolouration caused by the toluene-extractable matter present on the surface of the carbon black. The method may not be applicable to carbon blacks with a high extractable-matter content.

Specifies the agreed values for the properties of standard reference blacks (SRB) to be used in conjunction with methods of test for carbon black. Replaces the second edition.

Gives a method for the determination of the pellet size distribution of carbon black. Replaces the first edition which has been technically revised.

Describes adsorptive methods for the determination of the surface area of carbon blacks by means of hexadecyltrimethylammonium bromide (CTAB). Excluded is the area of micropores that are too small to admit molecules of CTAB. Cancels and replaces the first edition, which has been technically revised.

Specifies four methods for the determination of the specific surface area of types and grades of carbon black for use in the rubber industry: method A using the Ni-Count-1 apparatus, method B using the Areameter apparatus, method C using gas chromatography, method D using the Monosorb surface-area analyser. Somewhat different results may be obtained from the four methods. The degassing procedure differs from method to method, and it is important to investigate the possibility of correcting the results by using standard reference blacks (ISO/TR 12245:1994).

Cancels and replaces the second edition (1991). Specifies a method for the determination of the tinting strength of carbon black relative to an industry tint reference black. The method is based on the use of three different commercial instruments. Other instruments may be used but they shall have at least equivalent performance.

The system is used to classify rubber grade carbon blacks by the use of a four-character nomenclature system. The first character gives some indication of the influence of the carbon black on the rate of cure of a typical rubber compound containing the black, the second character gives information on the average particle size of the carbon black, and the last two characters are assigned arbitrarily. All rubber grade carbon blacks for which a number is currently assigned at the time of publication of this classification system are listed in two tables. Assignment of a number is exclusively the ASTM D-24 Committee's responsibility.

Specifies principle, reagent, apparatus, sample preparation, conditions of the test, procedure and the expression of the results. An annex is given for checking and adjusting the torque spring and hydraulic damping, another for checking the constant-rate burette.

Specifies a method for determining the water-wash sieve residue from regular, untreated carbon black for the rubber industry. It may not be applicable to oil-treated blacks because the oil could prevent proper wetting of the black by water.

Specifies a standard test formula for evaluation of carbon black in rubbers. Describes the evaluation of vulcanization characteristics as well as the tensile stress strain properties of vulcanized test mixes. Gives the contents of the test report.