1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 746B Polymeric Materials Long Term Property Evaluations STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRI
2、GHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Polymeric Materials Long Term Property Evaluations, UL 746B Fourth Edition, Dated April 4, 2013 SUMMARY OF TOPICS This revision of the Fourth Edition of ANSI/UL 746B was issue
3、d to incorporate the following change in requirements: 1. Removal of Two-Component Variable from Silicone Rubber Material Specied in Table 7.1 2. Assignment of a Generic Thermal Index Temperature of 85C to PPA in Table 7.1 3. Fixed Temperature Evaluation for Exceptionally Durable Materials Specied i
4、n Paragraph 13.4, new Table 13.2, and new Paragraph 13.4.1 The new and revised requirements are substantially in accordance with Proposal(s) on this subject dated August 5, 2016 and November 4, 2016. Text that has been changed in any manner or impacted by ULs electronic publishing system is marked w
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9、le purchaser is storing an electronic Standard on the purchasers computer system. DECEMBER 21, 2016 UL 746B tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL DECEMBER 21, 2016 UL 746B tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTH
10、ORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL April 4, 2013 (Title Page Reprinted: December 21, 2016) 1 UL 746B Standard for Polymeric Materials Long Term Property Evaluations First Edition September, 1975 Second Edition June, 1979 Third Edition August, 1996 Fourth Editi
11、on April 4, 2013 This ANSI/UL Standard for Safety consists of the Fourth Edition including revisions through December 21, 2016. The most recent designation of ANSI/UL 746B as an American National Standard (ANSI) occurred on December 21, 2016. ANSI approval for a standard does not include the Cover P
12、age, Transmittal Pages and Title Page. Comments or proposals for revisions on any part of the Standard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line Collaborative Standards Development System (CSDS) at https:/. ULs Standards for Safety are co
13、pyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2016 UNDERWRITERS LABORATORIES INC. ANSI/UL 746B-
14、2016UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL DECEMBER 21, 2016 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT
15、PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .5 2 References .5 3 Supplementary Test Procedures 5 4 Characteristics of Polymeric Materials .6 5 Use of Polymeric Materials .6 DETERMINATION OF THE RELATIVE THERMAL INDICES OF POLYMERIC MATERIALS 6 General 7 7 Relative Thermal Index Based Upon Histo
16、rical Record .8 8 Relative Thermal Index Based Upon Long-Term Thermal-Aging Programs 10 9 Apparatus .11 9.1 Ovens .11 10 Scope of Test Programs .12 10.1 Selection of test properties 12 11 Property-Evaluation Tests 13 11.1 General .13 11.2 Choice of end-point .14 12 Sampling Programs .14 13 Selection
17、 of Oven Temperatures 14A 14 Selection of Control Material 14B 15 Specimens .15 16 Thermal Aging 15 17 End-of-Life .19 17.1 Primary properties 19 17.2 Secondary properties .19 18 Proof Testing .20 19 Analysis and Evaluation .21 20 Related Material Coverage of Variations in Material Composition .26 2
18、0.1 General .26 20.2 Thermoplastic materials .26 20.3 Thermosetting molded materials .31 21 Aging, Specimen, and Check-Test Schedules 32 21.1 General .32 21.2 Polypropylene .32 21.3 Coating powders .33 22 Fixed Time Sampling Method 39 22.1 General .39 22.2 Screening Procedure .39 22.3 Remainder of F
19、ixed Time Sampling Method .40 RELATIVE THERMAL INDEX CLASS 23 Assignment of Temperature Classications 40 MARKING 24 General 41 DECEMBER 21, 2016 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMI
20、SSION FROM UL SUPPLEMENT SA - FOLLOW-UP INSPECTION INSTRUCTIONS INTRODUCTION SA1 Scope SA1 SA2 Glossary SA1 SA3 Responsibility of the Manufacturer .SA2 SA4 Responsibility of the Field Representative SA3 SA5 Selection of Samples for Follow-Up Testing .SA3 SA6 Follow-Up Test Program SA3 DECEMBER 21, 2
21、016 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements cover long-term test procedures to be used for the evaluation of materials used for
22、 parts intended for specic applications in end products. 1.2 Together with the Standards mentioned in Supplementary Test Procedures, Section 3, these investigations provide data with respect to the physical, electrical, ammability, thermal, and other properties of the materials under consideration a
23、nd are intended to provide guidance for the material manufacturer, the molder, the end-product manufacturer, safety engineers, and other interested parties. 2 References 2.1 Any undated reference to a code or standard appearing in the requirements of this standard shall be interpreted as referring t
24、o the latest edition of that code or standard. 3 Supplementary Test Procedures 3.1 The Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL 94, covers ammability of polymeric materials used for parts in devices and appliances. The Standard for Polymeric Ma
25、terials Short Term Property Evaluations, UL 746A, contains short-term test procedures to be used for the evaluation of materials used for parts intended for specic applications in electrical end products. The Standard for Polymeric Materials Fabricated Parts, UL 746D, contains requirements for trace
26、ability and performance of parts molded and fabricated from polymeric materials. 3.2 Programs for the investigation of material part modications, such as the plating of plastics or the use of ame-retardant paints, are contained in the Standard for Polymeric Materials Use in Electrical Equipment Eval
27、uations, UL 746C. 3.3 Data concerning the effect of various environments and contaminants upon the properties of materials can also be obtained through standard test procedures. The more commonly used procedures are briey described in the Standard for Polymeric Materials Short Term Evaluations, UL 7
28、46A. 3.4 Test procedures are provided in the Standard for Polymeric Materials Use in Electrical Equipment Evaluation, UL 746C, for the evaluation of polymeric materials in specic applications in end products. These test procedures include references to the data obtained from the standard property te
29、sts as well as other practical means of evaluation. 3.5 Requirements for materials that have been modied to match the requirements of a specic application, including the use of recycled and regrind materials, the use of additives and colorants, and the blending of two or more materials, are describe
30、d in the Standard for Polymeric Materials Fabricated Parts, UL 746D. APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 4 Characteristics of Polymeric Materials 4.1 Pol
31、ymeric materials include thermoplastic, thermosetting, and elastomeric materials. A thermoplastic material can be easily softened and resoftened by repeated heating. A thermosetting material cures by chemical reaction and, when cured, cannot be resoftened. An elastomeric material is capable of being
32、 stretched at room temperature to at least twice its length under low stress and recovers to its original length when released from the stress. 4.2 Characteristics of polymeric materials that necessitate additional consideration include: a) Mold stresses b) Insulating quality c) Resistance to igniti
33、on d) Extinguishing characteristics e) Production of smoke and gases f) Mechanical Strength g) Compatibility with solvents h) Melting or distortion i) Cold ow, if under stress j) Fuel contribution k) Dimensional stability 5 Use of Polymeric Materials 5.1 The reduction to an acceptable level of the r
34、isks of electric shock, re, and personal injury from electrical equipment depends upon the selection of materials, design, and processing of parts as well as the assembly, mounting, and relative positions of these parts. 5.2 The properties needed by individual parts are dened by the function or func
35、tions of the part. An enclosure, for example, must ordinarily be designed to withstand mechanical abuse. Accordingly, a material known to have substantial impact strength would normally be used although a material that has a lower impact strength, but is reinforced, might also be acceptable. 5.3 Ele
36、ctrical equipment of necessity employs many materials that usually have divergent properties. The ability to match the demands of the application with the characteristics of a material as well as the ability to compare the properties of one material with those of another can lead to an acceptable se
37、lection of materials. APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIONS - UL 746B 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 5.4 The information gained from the data obtained from these tests can be used as an aid in the
38、 evaluation of electrical equipment using parts made of polymeric materials. Knowledge of materials can be obtained from an analysis of data from standard tests conducted on small specimens. DETERMINATION OF THE RELATIVE THERMAL INDICES OF POLYMERIC MATERIALS 6 General 6.1 A relative thermal index o
39、f a material is an indication of the materials ability to retain a particular property (physical, electrical, etc.) when exposed to elevated temperatures for an extended period of time. It is a measure of the materials thermal endurance. For each material, a number of relative thermal indices can be
40、 established, each index related to a specic property and a specic thickness of the material. 6.2 In determining the relative thermal index of a material, the basic concepts to be followed are stated in the Institute of Electrical and Electronics Engineers Specications No. 1, General Principles for
41、Temperature Limits in the Rating of Electrical Equipment; No. 98, Guide for the Preparation of Test procedures for the Thermal Evaluation of Electrical Insulating Materials; No. 101, Guide for the Statistical Analysis of Thermal Life Test Data. 6.3 The relative thermal index of a material is to be b
42、ased upon an evaluation of long-term thermal-aging data obtained under the program described in Relative Thermal Index Based Upon Long-Term Thermal-Aging Programs, Section 8. Thermal indices on a generic basis have been established through knowledge of extensive eld-service records, as outlined in R
43、elative Thermal Index Based Upon Historical Record, Section 7. Relative thermal indices may also be established based upon a study and evaluation of the interrelationship of all of the data mentioned in Supplementary Test Procedures, Section 3, which can also be coupled with knowledge concerning the
44、 materials performance in insulating systems gained through experience or long-term aging tests. 6.4 A comparison of the thermal-aging characteristics of one material of proven eld service at a particular temperature level with the thermal-aging characteristics of another material with no eld servic
45、e history provides a means for estimating the relative thermal index level at which the second material might also provide acceptable eld service. 6.5 Another explanation of a relative thermal index is the maximum temperature below which a material maintains its characteristics over a reasonable per
46、iod. This relative thermal index serves the very great need to evaluate materials that are exposed to heat sources in electrical products in which they are not used as part of an insulating system and in which they are not subjected to other major degradation inuences. It is to be assumed that neith
47、er excessively long nor excessively short duty cycles are involved. 6.6 To be valid for use in a specic application, a relative thermal index of a material must be established by a study of the degradation rates of all properties that are relied upon in that application. As a corollary to this princ
48、iple, more than one relative thermal index can be assigned to a material depending on the relative degradation rates of the properties of the material and depending on which of these properties are considered in establishing the indices. APRIL 4, 2013 POLYMERIC MATERIALS LONG TERM PROPERTY EVALUATIO
49、NS - UL 746B 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 7 Relative Thermal Index Based Upon Historical Record 7.1 Table 7.1 presents a list of materials, each of which is assigned a relative thermal index based on acceptable service experience, the chemical structure of the material, and a knowledge of the performance of the material in tests of insulating systems and electrical equipment. The assigned r
