1、SSPC-Paint 38April 1, 200611. Scope1.1 This specification covers the requirements for a high- performance single-component moisture-curing UV-stable polyurethane topcoat (ASTM D 16, Type II polyurethane). It is intended to be used as a topcoat that provides good color and gloss retention. 1.2 Coatin
2、gs meeting the requirements of this specifica-tion are generally suitable for exposures in environmental zones 1A (interior, normally dry), 1B (exterior, normally dry), 2A (frequently wet by fresh water, excluding immersion), 2B (frequently wet by salt water, excluding immersion), 3B (chemical expos
3、ure, neutral) and 3C (chemical exposure, alkaline).1.3 The specified coating is intended for application by brush, spray, or roller. It is generally applied over a primer or intermediate coating.2. Description2.1 This single-package moisture-curing polyurethane coating is characterized by the presen
4、ce of free polyisocyanate groups capable of reacting with atmospheric moisture in order to form a film.2.2 WEATHERING LEVELS: This specification contains three levels of accelerated and South Florida weathering performance that are discussed in Section 6.2.3. Referenced Standards3.1 The latest issue
5、, revision, or amendment of the refer-enced standards in effect on the date of invitation to bid shall govern, unless otherwise specified. Standards marked with an asterisk (*) are referenced only in the Notes, which are not requirements of this specification.3.2 If there is a conflict between the r
6、equirements of any of the cited referenced standards and this specification, the requirements of this specification shall prevail.3.3 SSPC STANDARD:Guide 13 Guide for the Identification and Use of Industrial Coating Materials in Computerized Product Databases3.4 AMERICAN SOCIETY FOR TESTING AND MA-T
7、ERIALS (ASTM) STANDARDS:1* D 16 Standard Terminology for Paint Related Coatings, Materials, and ApplicationsD 523 Standard Test Method for Specular Gloss* D 562 Standard Test Method for Consistency of Paints Measuring Krebs Units (KU) Viscosity Using the Stormer-Type ViscometerD 1014 Standard Practi
8、ce for Conducting Exterior Exposure Tests of Paints and Coatings on Metal Substrates* D 1296 Standard Test Method for Odor of Volatile Solvents and Diluents* D 1475 Standard Test Method for Density of Liquid Coatings, Inks, and Related Products* D 1535 Standard Practice for Specifying Color by the M
9、unsell System* D 1640 Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room TemperatureD 1849 Standard Test Method for Package Stability of PaintD 2244 Standard Test Method for Calculation of Color Tolerances and Color Differences From Instrumentally Measured Color
10、Coordinates* D 2369 Standard Test Method for Volatile Content of Coatings* D 2371 Standard Test Method for Pigment Content of Solvent-Reducible Paints* D 2621 Standard Test Method for Infrared Identification of Vehicle Solids from Solvent-Reducible Paints* D 2697 Standard Test Method for Volume Nonv
11、olatile Matter in Clear or Pigmented CoatingsSSPC: The Society for Protective CoatingsPAINT SPECIFICATION NO. 38Single-Component Moisture-Cure WeatherableAliphatic Polyurethane Topcoat, Performance-Based1 ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. Standards availabl
12、e online from http:/www.astm.org.2American National Standards Institute, 1819 L Street, NW, Suite 600, Washington, DC 20036. Standards available online from http:/www.ansi.org.SSPC-Paint 38April 1, 20062D 2794 Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformatio
13、n (Impact)D 3925 Standard Practice for Sampling Liquid Paints and Related Pigmented CoatingsD 4214 Standard Test Methods for Evaluating Degree of Chalking of Exterior Paint FilmsD 4541 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion TestersD 4587 Standard Practice for
14、Fluorescent UV-Condensation Exposures of Paint and Related CoatingsD 5402 Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent RubsG 154 Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials3.5 AMERICAN NATIONAL STAND
15、ARDS INSTITUTE (ANSI) STANDARD:2Z129.1 Hazardous Industrial Chemicals Precautionary Labeling3.6 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) STAN-DARD:3TP 67-03 Standard Method of Test for Analysis of Structural Steel Coatings for Isocyanate Content4. Composition Requi
16、rements4.1 RESIN REQUIREMENT: The resin used in the coating shall be a polyisocyanate-based product that cures through a chemical reaction with atmospheric moisture. Use of other resins or modifiers shall be minimal and limited to products necessary for formula ingredient compatibility and to improv
17、e recoating properties. Manufacturers formulations of single-component moisture-curing weatherable polyurethane topcoats normally contain levels of polyisocyanate in vehicle solids above 3.5% by weight. The method and formula for determining isocyanate content, developed by AASHTO as TP 67, is shown
18、 in the Annex. 4.2 VOC Content: See Note 12.1 for information on VOC content.5. Requirements of Liquid Coating5.1 PACKAGE STABILITY: Package stability shall be tested in accordance with ASTM D 1849. Storage conditions shall be 30 days at 52 1C (126 2 F). A change in consis-tency of greater than 10 K
19、rebs units or noncompliance with the application requirements shall be cause for rejection.5.2 APPLICATION PROPERTIES: All guidance provided by the manufacturer regarding thinning requirements and special application requirements shall be followed (see Note 12.2). Following the manufacturers directi
20、ons, the coating shall be easily applied by brush, roller, or spray. The coating shall have no streaking, running, or sagging or other defects during application or while drying.6. Weathering Requirements6.1 WEATHERING RESISTANCE: Two weathering test procedures are specified below. Test data may not
21、 be available for the desired color and gloss specified. Performance levels are established using whites and light colors. It is left to the discretion of the specifier whether to accept Florida data from a similar color or to use UV-A data in lieu of Florida weath-ering data. NOTE: Commercial test
22、sites in North America conforming to this requirement are located in southern Florida and Arizona. Other test sites may be used if agreed upon by the contracting parties.6.1.1 Accelerated Weathering: Accelerated weathering shall be performed in accordance with ASTM D 4587, Cycle 2. Test panels shall
23、 have a primer/intermediate coat as recommended by the manufacturer with a curing duration as mutually agreed upon by the manufacturer and the contracting parties.Apparatus Fluorescent UV/condensation apparatus complying with ASTM G 154.Procedure Test according to ASTM D 4587 Cycle 2 procedure. This
24、 eight-hour duration comprises one test cycle. Continue cycle testing to achieve the exposure hours defined in the required performance levels (as shown in Table 1).6.1.2 South Florida Weathering: South Florida weath-ering shall be performed in accordance with ASTM D 1014 (45 south exposure, washed
25、with mild detergent before readings are taken.) Test panels shall have a primer/intermediate coat as recommended by the manufacturer.6.1.3 Coating application shall be according to the manufacturers written recommendations. A minimum of three 2American National Standards Institute, 1819 L Street, NW
26、, Suite 600, Washington, DC 20036. Standards available online from http:/www.ansi.org.3American Association of State Highway and Transportation Officials, 444 North Capitol Street, NW, Suite 249, Washington DC 20001, 202-624-5800 (http:/www.transportation.org/aashto/home.nsf). SSPC-Paint 38April 1,
27、20063Months to Noticeable ChangeTABLE 2FLORIDA EXPOSURELevel 1Level 2Level 312 to 2324 to 4748 or more Noticeable change following Florida Exposure Testing is defined as a gloss reduction of 35% or more of the initial gloss value measured at a 60 angle or a color change greater than 3.0 E* C.I.E 197
28、6 L*A*B*(see Section 6.1.3 and Note 12.3).Hours to Noticeable Change Noticeable change following accelerated UV-A/Condensation testing is defined as a gloss reduc-tion of 25% or more of the initial gloss value measured at a 60 angle or a color change greater than 3.0 E* C.I.E.1976 L*A*B* (see Sectio
29、n 6.1.1 and Note 12.3).63 to 125126 to 250251 or moreTABLE 1TIME CORRESPONDING TO EACH PERFORMANCE LEVELAccelerated UV-A/ CondensationCycles to Noticeable ChangeLevel 1Level 2Level 3500 to 9991000 to 19992001 or moreMeasurement Test/Minimum CriteriaTABLE 3SUMMARY OF PERFORMANCE TESTING RESULTS TO BE
30、 REPORTEDAccelerated Weathering(Section 6.6.1)500 h1000 h2000 h25% from original readingLevel 1Level 2Level 3Color Changeless than 3.0 E* C.I.E 1976 L*A*B*South FloridaWeathering(Section 6.1.2)(ASTM D 1014)Level 1Level 2Level 312 mo24 mo48 mo35% from original readingColor Changeless than 3.0 E* C.I.
31、E 1976 L*A*B*Exposure TestMaximum Gloss Reduction, ASTM D 523Exposure TimePerformance LevelColor RetentionASTM D 2244 Smaller values of color change (less than 3.0 E*) may be visible to the eye, but the noticeable change maximum of 3.0 E* specified here is considered acceptable for most industrial a
32、nd marine applications. More stringent gloss and color retention requirements may be specified as needed.SSPC-Paint 38April 1, 20064panels shall be exposed. Each replicate panel must meet the minimum acceptance criteria. Clear coatings must be tested over the intended basecoat. Initially, and at the
33、 end of the exposure period for each level, tristimulus color values shall be measured according to ASTM D 2244, and 60 degree gloss shall be measured according to ASTM D 523. Table 3 summarizes the tests of Section 6 as well as the minimum acceptance criteria. See Note 12.3 regarding test results f
34、or darker colors.6.2 Performance Levels: Tables 1 and 2 specify the amount of time the coating must perform before noticeable change in order to achieve the defined performance level. Polyurethane topcoats are available in a wide range of color and gloss. Procurement documents shall state the desire
35、d level of performance, exposure method (in accordance with Tables 1 and 2), color, and gloss. For example, a specifier may require Level 2 Florida exposure, initial gloss greater than 80, matched to a specific color. A certain level of accelerated weathering does not necessarily correspond to a par
36、ticular level of atmospheric weathering and they need to be specified independently. These are two independent complementary tests for measuring coating performance. If no level is speci-fied, Level 3 will be assumed.47. Laboratory Physical Tests of Applied Coatings7.1 RECOATABILITY: Intercoat and s
37、ubstrate adhesion properties of the polyurethane topcoats shall be determined by measurement of adhesion values between:a) primer and the substrate, b) polyurethane topcoat and the primer or intermediate coat, and, if applicablec) the second coat of polyurethane topcoat and the same previously appli
38、ed topcoat.Coating manufacturers shall provide acceptable window (time frame) ranges between application of coatings in a multi-coat system. Unless the purchaser specifically requests a variance, the maximum dry film thickness and the minimum curing time (with reported conditions for temperature and
39、 humidity) as stated on the manufacturers product data sheets will be used for coating application prior to adhesion testing. All testing shall be performed on a minimum of three steel test panels each with minimum dimensions of 75 x 150 x 5 mm (3 x 6 x 1/4 inches). The panels shall be prepared to t
40、he minimum surface preparation recommendations of the coating manufacturer.7.2 ADHESION 7.2.1 Primer Adhesion to Steel Substrate: Apply the primer to the steel panel and cure according to the manufac-turers recommendations. Test adhesion according to ASTM D 4541, and identify the type of adhesion te
41、ster used (Type II, III, IV, or V). The minimum adhesion acceptance value of the primer to the substrate shall be 4.1 MPa (600 psi).7.2.2 Polyurethane Topcoat Adhesion to the Primer: Apply topcoat to panels (previously primed as described in 7.2.1) and cure according to the manufacturers recommenda-
42、tions. Test the intercoat adhesion between topcoat and primer or intermediate coat in accordance with ASTM D 4541, and identify the type of adhesion tester used. Intercoat adhesion is defined as the force required to separate the topcoat from the underlying coat. The minimum intercoat adhesion accep
43、-tance value of the topcoat to the primer shall be 4.1 MPa (600 psi).7.2.3 Polyurethane Topcoat Adhesion to (Same) Previ-ously Applied Topcoat: Apply a second coat of topcoat, and cure according to the manufacturers recommendations. Test 4 Note: Maximum gloss reduction values shown in Table 1 (25%)
44、and Table 2 (35%) are specific for these different test methods (see Section 6.1). The maximum allowable gloss reduction and color change values for Accelerated UV-A/Condensation and Florida Exposure were derived from experience provided by resin and coating manufacturers, end-users and coating spec
45、ification engineers who have actively participated on the SSPC Polyurethane Coatings Committee.TABLE 4REQUIRED PROPERTIESTest ASTM Result (Units) Minimum Acceptable ValuesAdhesionDirect Impact ResistanceSolvent (MEK) ResistanceEvaluating degree of chalking of exterior paintsD 4541D 2794D 54024.1 (60
46、0)6.8 (60)1006, where 10 is no chalking*D 4214MPa (psi)Nm (inch-lb)Number of double-rubsPhotographic standard rating method* At desired weathering level.SSPC-Paint 38April 1, 20065the intercoat adhesion in accordance with ASTM D 4541, and identify the type of adhesion tester used. The minimum interc
47、oat adhesion shall be 4.1 MPa (600 psi). 7.3 Polyurethane topcoat cohesion (bond strength within a single layer of coating) shall be equal to or greater than the minimum acceptable intercoat adhesion.7.4 Properties required of the polyurethane topcoat are described in Table 4, which includes the cor
48、responding ASTM test methods.8. Material Quality AssuranceTests may be used to determine the acceptability of a lot or batch of a qualified coating (see Note 12.4). 9. Labeling 9.1 Labeling shall conform to ANSI Z129.19.2 Technical data shall be provided for at least all data elements categorized as
49、 “essential” in SSPC-Guide 13. The specifier may require additional data to satisfy quality assur-ance or local regulatory requirements.10. Inspection10.1 All coatings supplied under this specification are subject to timely inspection by the purchaser or an authorized representative. The purchaser shall have the right to reject any materials supplied that are found to be defective under this specification (see Note 12.5). In case of dispute, unless otherwise specified, the arbitration or settlement procedure established in the procurement documents shal
