【国外标准】 Standard Specification for Rubber—Concentrated, Ammonia Stabilized, Creamed, and Centrifuged Natural Latex

4.1 This specification denotes limits on the 5 categories of latex as defined in the scope and defines the test methods to use for the specified properties. These test methods may be used for production control or for referee purposes.AbstractThis specification establishes the requirements for first grade concentrated natural rubber latex of the following categories: Category 1, centrifuged Hevea natural latex preserved with ammonia only or by formaldehyde followed by ammonia; Category 2, creamed Hevea natural latex preserved with ammonia only or by formaldehyde followed by ammonia; Category 3, centrifuged Hevea natural latex preserved with low ammonia with other necessary preservatives; and Category 4, centrifuged, or centrifuged and creamed, guayule latex, or other natural rubber latex, containing a specified dry weight amount of latex, with ammonia or other hydroxide, with other necessary preservatives and stabilizers. This specification applies to natural latex sources other than Hevea brasiliensis but does not apply to compounded latex concentrates. Materials shall be tested by analytical procedures that determine the following chemical properties an substances: total solids; dry rubber content; protein content; total alkalinity; viscosity; sludge content; coagulum content; KOH number; pH; mechanical stability; copper and manganese; density; volatile fatty acids; boric acid; and dry films.1.1 This specification covers requirements for first grade concentrated natural rubber latex (see Table 1) of the following categories:Category 1—Centrifuged Hevea natural latex stabilized with ammonia only.Category 2—Creamed Hevea natural latex stabilized with ammonia only.Category 3—Centrifuged Hevea natural latex stabilized with low ammonia.Category 4—Centrifuged, or centrifuged and creamed, guayule latex, or other natural rubber latex, containing less than 200 µg total protein per gram dry weight of latex, with ammonia or other hydroxide.Category 5—Centrifuged Hevea natural latex treated with aluminum hydroxide or by other means, stabilized with ammonia only containing less than 0.5 % non-rubber content.1.2 This specification is not necessarily applicable to latices prepared, stabilized, or preserved by other methods, and shall not be construed as limiting the desirability or usefulness of other categories of latices. It does apply to natural latex sources other than Hevea brasiliensis but does not apply to compounded latex concentrates.1.3 The analytical procedures applicable to the specifications are included and appear in the following order:  Section    Sampling 6 and 7    Total Solids 8 – 17    Dry Rubber Content 18    Protein Content 19    Total Alkalinity 20    Viscosity 21    Sludge Content 22    Coagulum Content 23    KOH Number 24    pH 25    Mechanical Stability 26    Copper and Manganese 27    Density 28 – 40    Volatile Fatty Acids 41 – 45    Boric Acid 46    Dry Films 47    Precision for All Test Methods 481.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.