1、Designation: D4676 94 (Reapproved 2017)Standard Classification forRubber Compounding MaterialsAntidegradants1This standard is issued under the fixed designation D4676; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This classification covers antidegradants used in rubberand where appropriate defines their important chemical andphysica
3、l characteristics for use in rubber.1.2 The general term “antidegradant” describes materialsused in rubber to protect against the effects of oxygen andozone. Materials that fall in this general category include bothantioxidants and antiozonants.1.3 This standard does not purport to address all of th
4、esafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1218 Test Method for Refra
5、ctive Index and RefractiveDispersion of Hydrocarbon LiquidsD1519 Test Methods for Rubber ChemicalsDeterminationof Melting RangeD1747 Test Method for Refractive Index of Viscous Mate-rialsD2702 Practice for Rubber ChemicalsDetermination ofInfrared Absorption CharacteristicsD3461 Test Method for Softe
6、ning Point of Asphalt and Pitch(Mettler Cup-and-Ball Method)D4571 Test Methods for Rubber Compounding MaterialsDetermination of Volatile MaterialD4574 Test Methods for Rubber Compounding MaterialsDetermination of Ash ContentD4937 Test Method forp-Phenylenediamine AntidegradantsPurity by Gas Chromato
7、graphyD5376 Test Method for Rubber Compounding MaterialsDetermination of the Basic Nitrogen Content in RubberAntioxidant: Polymerized TMQE28 Test Methods for Softening Point of Resins Derivedfrom Pine Chemicals and Hydrocarbons, by Ring-and-Ball Apparatus3. Significance and Use3.1 There are many dif
8、ferent antidegradants available foruse in the rubber industry.3.2 This classification of the various materials covers theirchemical structure along with a brief reference to their overalluse and their properties.4. Basis of Classification4.1 Rubber antidegradants included in this classificationdocum
9、ent are divided into the six classes shown below. Theclassification in general is based on the chemical structurecategorization but in most cases it also classifies the materialsaccording to their potential rubber applications.4.2 Class 1, p-Phenylenediamines (PPDs)This group ofadditives represents
10、the primary materials used in tires andother mechanical goods to impart ozone protection. Theseadditives are also used as antioxidants and antiflex agents in anumber of applications but are considered to be stronglystaining and thus limited to black rubber applications. They canalso be used as raw p
11、olymer stabilizers.4.2.1 Although all PPDs have similar performancecharacteristics, the different types are frequently preferred forcertain end use conditions; for example, selection is based onthe type and degree of flexing to be experienced by the rubberarticle.4.3 Class 2, Trimethyl-dihydroquinol
12、ines (TMQs)Thesematerials are primarily used to protect rubber articles fromdegradation by atmospheric oxygen at higher temperatures.They are moderately staining.4.3.1 Although all TMQs have similar performancecharacteristics, different types are frequently preferred toaccommodate processing or end
13、use needs.4.4 Class 3, PhenolicsPhenolic antidegradants represent agroup of “nonstaining” and “nondiscoloring” additives usedprimarily in light colored mechanical goods and tires. They canalso be employed as raw polymer stabilizers. The term “non-discoloring” is used somewhat loosely, as products yi
14、elding1This classification is under the jurisdiction of ASTM Committee D11 onRubber and Rubber-like Materials and is the direct responsibility of SubcommitteeD11.20 on Compounding Materials and Procedures.Current edition approved Feb. 1, 2017. Published February 2017. Originallyapproved in 1987. Las
15、t previous edition approved in 2012 as D4676 94 (2012).DOI: 10.1520/D4676-94R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page
16、onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theD
17、evelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1slight discoloration are included in this classification. This isdone to distinguish them from the strongly staining anddiscoloring amine type antideg
18、radants (for example, PPDs).4.4.1 The different types of phenolic antidegradant affordvarying degrees of protection against oxidation, heat aging,rubber “poisons,” and crazing. In general they are weakerantioxidants than the staining amines types.4.5 Class 4, Alkylated Diphenylamines (DPAs)This clas
19、sof additives is generally considered representative of substi-tuted amine antioxidants and they are used as raw polymerstabilizers and in vulcanizate applications. They are moder-ately discoloring and staining.4.6 Class 5, Aromatic PhosphitesThese are phosphorouscontaining fully nonstaining-nondisc
20、oloring additives used asstabilizers for synthetic elastomers in “white rubber” applica-tions. They also have application as peroxide decomposers andradical traps in many polymer systems.4.7 Class 6, Diphenylamine-Ketone CondensatesThisgroup of additives is used primarily in carbon black loadedcompo
21、unds to protect against both oxygen and heat deteriora-tion.5. Basic Description of Antidegradants5.1 p-PhenylenediaminesThe individual materials in theclass of compounds designated as p-phenylenediamines vary inchemical structure and in performance characteristics depend-ing on the substitution on
22、the nitrogen atoms in the parentcompound, p-phenylenediamine. The three general types ofPPDs used in rubber are defined below:5.1.1 PPD Type I: N,N-dialkyl-p-phenylenediamines (seeFig. 1)R and R1are secondary alkyl groups, usually C6orlarger. These additives are generally liquids at ambient condi-ti
23、ons and represent single chemical components (90 %).5.1.2 PPD Type II: N-alkyl-N-aryl-p-phenylenediamines(see Fig. 2)R is a secondary alkyl group and R1is hydrogenor a primary alkyl substituent (usually methyl). These productsgenerally consist of a single component or purposeful mixtureof two or mor
24、e major components. They can be either liquidsor solids.5.1.3 PPD Type III: N,N-diaryl-p-phenylenediamines (seeFig. 3)R and R1can be the same or different groupsconsisting of hydrogen or alkyl groups (usually methyl).Therefore, this type can be individual components or mixturesof three or more isome
25、rs. This type of PPD is generally solidat ambient conditions.5.2 Trimethyl-dihydroquinolinesCompounds designatedas TMQs represent a group of antidegradants based on polym-erized aniline-acetone condensation products. The individualproducts differ by the degree of polymerization as well as theratio o
26、f aniline to acetone in the monomer preparation.5.2.1 Since these products are complex mixtures they arebest described with chemical reactions (see Fig. 4).5.2.2 The generally accepted chemical structure for TMQoligomers (polymers) is given in Fig. 5.5.2.3 Alternate structures may also be present co
27、ntaininganiline end groups or acetone bridges, or both, as shown in Fig.6.5.2.4 Other complex structures are also present in all TMQproducts. The precise nature of the oligomeric mixture is afunction of the monomer preparation conditions, monomerpurification, and polymerization conditions.5.3 Phenol
28、icsPhenolic antioxidants are classified chemi-cally according to the number of phenolic groups in themolecule. In general the more sterically hindered phenolicantioxidants are less discoloring but have lower antioxidantactivity in rubber applications.5.3.1 Monofunctional phenols (Type I) are frequen
29、tly re-ferred to as hindered phenols. They develop little discolorationhowever they show the weakest antioxidant activity and arerelatively volatile due to the low molecular mass. Theirprimary use is as polymer stabilizers. In the general structure(see Fig. 7), R1, R2, and R3can be hydrogen, alkyl,
30、aryl,aralkyl, or thioalkyl groups, or a combination thereof. Thesegroups may also contain carboxylic acid esters, thioesters, ortriazine functions.5.3.2 Bifunctional phenols (Type II) are also referred to ashindered bisphenols. They represent the most important classof phenolic antioxidants used in
31、rubber applications. In generalthey have good antioxidant activity with minimal discolor-ation. In the general structure (see Fig. 8 and Fig. 9), the Rgroups are normally located in the “ortho” or “para” position inrelation to the phenol function. R is generally alkylideneFIG. 1 Type IN-N-dialkyl-p-
32、phenylenediaminesFIG. 2 Type IINalkylNarylpphenylenediaminesFIG. 3 Type IIIN,Ndiaryl pphenylenediaminesFIG. 4 TMQ ChemistryFIG. 5 TMQ Oligomeric StructureD4676 94 (2017)2(methylene) or thio. R1, R2, R3, and R4can be hydrogen, alkyl,aryl, aralkyl, or thioalkyl groups, or a combination thereof. The“or
33、tho” bridged structures (Fig. 8) are commonly used inrubber.5.3.3 Multifunctional phenols (Type III) are similar to thebifunctional phenols in activity and discoloration but are morepersistent in the end use product due to higher molecular massand lower volatility. In the generalized structure (see
34、Fig. 10and Fig. 11), the R groups are defined in 5.3.2. The substitutionis also normally in the “ortho” and “para” positions relative tothe phenol group.5.4 Alkylated DiphenylaminesThese antioxidants arecomplex reaction products of diphenylamine and variousalkylating agents. The substituents are sel
35、ected to achieve adesired balance of cost and performance characteristics. In thegeneral structure (see Fig. 12) R can be hydrogen, alkyl, oraralkyl groups. There can be multiple substituents on either orboth rings. Alternate structures also have substituents on thenitrogen atom.5.5 Aromatic Phosphi
36、tesAromatic phosphites are phos-phorous esters of aromatic phenols. In the general structure(see Fig. 13) the R groups can be hydrogen, alkyl, aryl, oraralkyl.5.6 Diphenylamine-Ketone CondensatesThese antioxi-dants are complex reaction products of diphenylamine andalkyl ketones, primarily acetone (s
37、ee Fig. 14), some of whichare further condensed with formaldehyde producing productsof high molecular weight. They are low melting resins orliquids, essentially non-volatile and readily dispersable inrubber.6. Composition and Properties6.1 The important properties and characteristics of an-tidegrada
38、nts vary with antidegradant class and intended appli-cation. Those composition and property characteristics listedbelow are judged to be more significant for one or more of theclasses or individual types of antidegradants being considered.6.2 Purity of AssayEven though performance is not di-rectly r
39、elated to chemical purity a measurement of purity isgenerally specified for those antidegradants used in highperformance applications. This parameter is particularly appli-cable to those antidegradants that represent individual (or adefined number) of specific chemical entities; that is, PPDs andmos
40、t phenolics.6.2.1 PPD purity should be determined according to a gaschromatographic method defined in Test Method D4937.6.2.2 The purity of phenolic antioxidants can be determinedby various chromatographic techniques including gas chroma-tography (GC) and high pressure liquid chromatography(HPLC). A
41、STM methods specific to these materials have notyet been developed. The melting point of solids (Test MethodsD1519) and the refractive index of liquids (Test MethodsD1218 and D1747) are often used as an indicator of purity.6.2.3 Since TMQs, alkylated diphenylamines, and phosphiteantidegradants gener
42、ally represent reaction mixtures ratherthan individual chemical entities, their quality is usuallyFIG. 6 TMQ Oligomers with Aniline End Groups and an AcetoneBridgeFIG. 7 Type I Phenolic AntioxidantsFIG. 8 “Ortho” Bridged Type II Phenolic AntioxidantsFIG. 9 “Para” Bridged Type II Phenolic Antioxidant
43、sFIG. 10 “Ortho” Bridged Type III Phenolic AntioxidantsFIG. 11 “Para” Bridged Type III Phenolic AntioxidantsFIG. 12 Alkylated Diphenylamine General StructureFIG. 13 Aromatic Phosphites General StructureFIG. 14 DiphenylamineKetone Condensate General StructureD4676 94 (2017)3established by indirect me
44、thods. HPLC or GC techniques, orboth, are being utilized to analyze these materials but ASTMprocedures have not been developed.6.2.3.1 This is accomplished for TMQs by measuring theamount of basic nitrogen by a perchloric acid titration (TestMethod D5376). This indirectly defines the relative propor
45、tionof reactants in the mixed product.6.2.3.2 The relative purity of the complex alkylated diphe-nylamines can be assessed by comparison of the ultravioletspectrum with that of standard or reference materials.6.2.3.3 The relative purity of mixed aromatic phosphites canbest be established from the in
46、frared (IR) spectrum obtainedaccording to Practice D2702. Comparison of the spectra withstandard or reference materials is required to obtain a qualityparameter.6.2.3.4 Melting range gives an indication of thediphenylamine-ketone condensate type and relative molecularweight within types. The infrare
47、d spectrum also is an indicatorof antidegradant type.6.3 Volatile Materials (including moisture) in antidegrad-ants can be important in some end use applications. A methodfor this determination in PPDs is given in Test Methods D4571.6.4 Ash ContentThe presence of ash or noncombustiblesin antidegrada
48、nts is important for applications where inorganicresidues in the rubber compound would present an end useproblem (undissolved or undispersed inorganics in rubberformulations could initiate flaws). Ash measurement on PPDsis described in Test Methods D4574. This methodology couldbe adapted to the othe
49、r antidegradant classes.6.5 Softening PointThis parameter has typically been usedto characterize TMQ antidegradants since these materials aregenerally not crystalline solids. The softening point is indica-tive of the degree of TMQ oligomerization. The determinationcan be done according to Test Method D3461 or with TestMethods E28.6.6 Hydrolysis StabilityOne particularly important char-acteristic of aromatic phosphite antioxidants is their relativeresistance to hydrolysis, since these materials are typicallyadded as aqueous emulsions. The
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