Aliphatic Polyurea Topcoat Application
PAINT SPECIFICATION NO. 39 – Two-Component Aliphatic Polyurea Topcoat Fast or Moderate Drying, Performance-Based
1.1 This speciﬁcation contains performance requirements for a two-component, weatherable polyurea topcoat. The coating may be fast or moderately fast drying (see Note 12.1).
1.2 Coatings meeting the requirements of this speciﬁcation are generally suitable for exposures in Environmental Zones 1A(interior, normally dry), 1B (exterior, normally dry), 2A (frequently wet by fresh water, excluding immersion), and 2B (frequently wet by saltwater, excluding immersion). Resistance of polyurea topcoats in Environmental Zones 3B (chemical exposure, neutral) and 3C (chemical exposure, alkaline) can vary based upon formulation. The coating manufacturer should be contacted for speciﬁc chemical resistance data if required.
1.3 The speciﬁed coating is intended for application by single-component airless spray, electrostatic spray, or plural-component equipment, depending upon its formulation.
1.4 This paint coating is intended for use as a topcoat over suitably primed ferrous metal and cementitious substrates.
2.1 The resins used in the coating shall result in a polyurea product as described in Notes 12.1.1 and 12.1.2 or a hybrid system as described in Note 12.2. This coating is comprised primarily of polyamine and polyisocyanate resins that react to form a polyurea topcoat.
2.2 COATING TYPE: The two types of polyurea coatings are differentiated by drying time.
2.2.1 Type 1 (Fast Drying): A Type 1 coating dries to handle in less than 30 minutes (per ASTM D 1640).
2.2.2Type2 (Moderate Drying): AType2coatingdries to handle from 30 minutes to 2 hours (per ASTM D 1640).
2.3 RESIN TYPES: A coating meeting the requirements of this speciﬁcation shall be a hindered aliphatic polyurea, non-hindered aliphatic polyurea, or hybrid coating (see Notes
12.1 and 12.2).
2.4 WEATHERING LEVELS: This specification contains three levels of accelerated weathering (Levels 1A, 2A and 3A) and two levels of outdoor weathering performance (Levels 1N and 2N). Table 1 speciﬁes the amount of time the coating must perform before noticeable color and gloss change in order to achieve the required performance level as deﬁned in paragraphs 2.4.1 through 2.4.5 and Table 1. A certain level of accelerated weathering does not necessarily correspond to a particular level of atmospheric weathering. The speciﬁer shall stipulate the requirements for outdoor weathering, accelerated weathering, or both. These are two independent, complementary tests for measuring coating performance. If no performance level and/or speciﬁc weathering test is speciﬁed, Level 3A for accelerated weathering (longest accelerated exposure) will be assumed.
2.4.1 Level 1A: Level 1A coatings have been evaluated for 500 hours in accelerated weathering testing.
2.4.2 Level 2A: Level 2A coatings have been evaluated for 1000 hours in accelerated weathering testing.
2.4.3 Level 3A: Level 3A coatings have been evaluated for 2000 hours in accelerated weathering testing.
2.4.4 Level 1N: Level 1N coatings have been evaluated for 12 months in natural exterior weathering testing.
2.4.5 Level 2N: Level 2N coatings have been evaluated for 24 months in natural exterior weathering testing.
Typical specular gloss levels are shown in Note 12.3.
Polyurea topcoats are available in a wide range of color and gloss. Procurement documents shall state the desired level of performance, exposure method, color, and gloss. For example, a speciﬁer may require Level 2N outdoor exposure, initial gloss greater than 80, matched to a speciﬁc color.
2.5 This speciﬁcation addresses performance properties of only white and pastel colored coatings. Because dark pigments are more sensitive to ultraviolet degradation, testing of individual coatings in deep tones and safety colors is necessary to establish their color and gloss retentive properties.
3. Referenced Standards
3.1 The latest issue, revision, or amendment of the referenced documents in effect on the date of invitation to bid shall govern unless otherwise speciﬁed. Those documents marked with an asterisk (*) are referenced only in the Notes or the Appendix, which are not requirements of this speciﬁcation.
3.2 If there is a conﬂict between the requirements of any of the cited reference documents and this speciﬁcation, the requirements of this speciﬁcation shall prevail.
3.3 SSPC STANDARDS:
|SSPC Guide 13||
Guide for the Identiﬁcation and Use of Industrial Coating Material in Computerized Product Databases
Measurement of Dry Film Thickness with Magnetic Gages
3.4 ASTM INTERNATIONAL STANDARDS:
1 D 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 Viscometer
D 1014 Standard Practice for Conducting Exterior Exposure Tests of Paints on Steel
D 1296 Standard Test Method for Odor of Volatile Solvents and Diluent
D 1475 Standard Test Method for Density of Liquid Coatings, Inks, and Related Products
D 1535 Standard Practice for Specifying Color by the Munsell System
D 1640 Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature
D 1849 Standard Test Method for Package Stability of Paint
D 2244 Standard Test Method for Calculation of Color Differences from Instrumentally Measured Color 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 3925 Practice for Sampling Liquid Paints and Related Pigmented Coatings
D 4541 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers
D 4587 Standard Practice for Fluorescent UV-Condensation Exposures of Paint and Related Coatings
D 5402 Standard Practice for Assessing the Solvent Resistance of Organic Coatings Using Solvent Rubs
3.5 AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) STANDARD:
2Z129.1 Hazardous Industrial Chemicals – Precautionary Labeling
3.6 FEDERAL SPECIFICATIONS AND STANDARDS:
3 FED-STD-141: Paint, Varnish, Lacquer and Related Materials: Methods of Inspection, Sampling and Testing
3 *Method 3011 Condition in Container
Method 4331 Spraying Properties
4.1 This is a performance-based coating speciﬁcation, there fore the manufacturer is given wide latitude in the selection of materials and manufacturing processes (see Note 12.4).
4.2 RESIN REQUIREMENT: There active components used in the coating shall be comprised primarily of polyamine and polyisocyanate resins that react to form a polyurea (see Notes 12.1 and 12.2).
5. Standard Testing Conditions
5.1 TEST PANELS [each test speciﬁes the number of replicates]: Panel size shall be 75 x 150 x 5 mm (3 x 6 x 3/16 inches) or greater. All test panels shall be coated with the primer recommended by the topcoat manufacturer. Follow the primer manufacturer’s instructions for surface preparation, application, and cure of the primer.
5.2 APPLICATION: In accordance with the manufacturer’s written recommendations, the topcoat shall be spray-applied in a single coat or multiple coats.
5.3 DRY FILM THICKNESS: The minimum dry ﬁlm thickness (DFT) of the test panels shall be the manufacturer’s written recommended minimum thickness. If there is no recommended ﬁlm thickness, then the minimum DFT shall be 150 micrometers (6.0 mils). The maximum DFT of the test panels shall be 50 micrometers (2.0 mils) more than the minimum or 135% of the minimum, whichever is greater. The DFT shall be measured in accordance with Appendix 5 of SSPC-PA 2.
1 ASTM, 100 Barr Harbor Road, West Conshohocken PA, 19248, (http://www.astm.org).
2 ANSI, 1819 L Street, NW, Washington, DC 20036, (http://www.ansi.org).
3 FED-STD 141 may be obtained from http://assist.daps.dla.mil.
4 The 30-day cure requirement is based on obtaining optimal mechanical properties that may be required by some speciﬁers.
5 It is recognized that under controlled laboratory conditions with speciﬁc coatings, higher adhesion values (above 4.1 MPa/600 psi) can be readily obtained. By committee consensus, a minimum recoatibility adhesion level of 4.1 MPa (600 psi) was deemed acceptable for testingdeﬁned in Section 5.3 based on ﬁeld experience of committee personnel and examination of other referenced standards that have withstood the test of time. ASTM D 5144-97, para 8.1.1 “Standard Guide for Use of Protective Coatings in Nuclear Power Plants” and ANS.
SSPC-Paint 39 April 1, 2004
5.4 CURE: Before any testing, the coating shall be dried and cured in accordance with the manufacturer’s written recommendations, or otherwise shall be aged for a minimum of 30 days in an environment with a relative humidity of 50 ± 10% and an ambient temperature of 25 ± 2°C (77 ± 5°F).4
5.5 BACKS AND EDGES: Coat and seal all edges and the back of each panel with a coating or tape that will provide the necessary protection to these surfaces.
6. Requirements of Liquid Coating
6.1 APPLICATION PROPERTIES: All guidance provided by the manufacturer regarding mixing of multi-component products, thinning requirements, and special application requirements shall be followed. The coating shall be easily applied by spray when tested in accordance with FED-STD141, Method 4331. The paint shall show no streaking, running, or sagging during application or while drying.
6.2 PACKAGE STABILITY: Package stability shall be tested in accordance with ASTM D 1849. Storage conditions shall be 30 days at 52 ± 1°C (125 ± 2°F). A change in consistency of greater than 10 Krebs units or noncompliance with the application requirements shall be cause for rejection.
7. Physical Tests of Applied Films
7.1 ADHESION TESTS: Adhesion properties of the polyurea topcoat shall be determined by measurement of adhesion values between:
a.) the polyurea topcoat and the primer, and if applicable
b.) the second coat of polyurea topcoat and the same previously applied topcoat.
The coating manufacturer shall provide an acceptable time frame 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 humidity) as stated on the manufacturer’s product data sheets shall be used for coating application prior to adhesion testing.
7.1.1 Topcoat Adhesion to Primer: Prepare three panels according to Sections 5.1 through 5.4. Test adhesion according to ASTM D 4541, Type III or Type IV, with three pulls on each of the three replicate panels. At least two of the pulls on each panel as well as the average of the three pulls on each panel shall be at least 4.1 MPa (600 psi). 5 One pull on each panel may be as low as 3.4 MPa (500 psi).
7.1.2 Recoatability: Prepare three panels according to Sections 5.1 through 5.4. Apply a second coat of topcoat and cure according to the manufacturer’s recommendations. Test adhesion according to ASTM D 4541, Type III or Type IV, with three pulls on each of the three replicate panels. At least two of the pulls on each panel as well as the average of the three pulls on each panel shall be at least 4.1 MPa (600 psi).5 One pull on each panel may be as low as 3.4 MPa (500 psi).
7.2 SOLVENT RESISTANCE: Prepare three panels according to Sections 5.1 through 5.4. Conduct a solvent resistance test on each panel in accordance with ASTM D 5402 using 100 double rubs of MEK solvent. When viewed without magniﬁcation, no topcoat shall be visible on the cloth.
7.3 DRY TIME: Spray the topcoat onto a suitable test panel at the maximum thickness recommended by the manufacturer. Test the topcoat for Dry-Through (or Dry-To-Handle) Time in accordance with ASTM D 1640.
7.3.1 A Type 1 topcoat must be dry in less than 30 minutes.
7.3.2 A Type 2 topcoat must be dry in 30 minutes to 2 hours.
8. Weathering Requirements
8.1 WEATHERING RESISTANCE: Two weathering test procedures are described below. Test data may not be available for the desired color and gloss speciﬁed. Performance levels are established using whites and light colors. Outdoor testing, as described in Section 8.1.2, is preferred. If outdoor weathering test data is not available for the desired color and gloss speciﬁed, accelerated test data shall be used until outdoor weathering data becomes available. It is left to the discretion of the speciﬁer whether to accept outdoor data from a similar color or to use UV-A data in lieu of outdoor weathering data. The natural weathering site shall have a daily average total ultraviolet radiation of 1±0.1 MJ/m2. [NOTE: Commercial test 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. Sixty-degree specular gloss shall be measured in accordance with ASTM D 523 and tristimulus color measured according to ASTM D 2244 at the beginning and end of the time period deﬁned by the required performance level.
8.1.1 Accelerated Weathering: Triplicate test panels shall be prepared in accordance with Sections 5.1 through 5.4. Accelerated weathering shall be performed in accordance with ASTM D 4587, Cycle 2. Sixty-degree gloss shall be measured according to ASTM D 523 and tristimulus color measured according to ASTM D 2244 at the beginning and end of the time period deﬁned in the selected level. The coating shall meet the weathering test requirements in Table 1 for the required performance level.
220.127.116.11 Level 1A: Products conforming to this performance level shall have a maximum gloss reduction of 20% and maximum color change of 2.0 ΔE*per ASTMD2244 after 500 hours exposure.
18.104.22.168 Level 2A: Products conforming to this performance level shall have a maximum gloss reduction of 30% and maximum color change of 3.0 ΔE* after 1000 hours exposure.
22.214.171.124 Level 3A: Products conforming to this performance level shall have a maximum gloss change of 40% and a maximum color change of 3.0 DE* after 2000 hours exposure.
8.1.2 Outdoor Weathering: Triplicate test panels shall be prepared in accordance with Sections 5.1 through 5.4. Outdoor weathering shall be performed in accordance with ASTM D 1014 (45-degree south exposure, washed with mild detergent.). Sixty-degree gloss shall be measured according to ASTM D 523 and tristimulus color measured according to ASTM D 2244 both initially and at the end of each level period. The coating shall meet the weathering test requirements at the beginning and at the end of the time period deﬁned in the selected performance level.
126.96.36.199 Level 1N: Products conforming to this performance level shall have a maximum gloss change of 35% and a maximum color change of 2.0 ∆E* after a 12-month exposure.
188.8.131.52 Level 2N: Products conforming to this performance level shall have a maximum gloss change of 50% and a maximum color change of 3.0 ∆E* after a 24-month exposure.
9.1 Labeling shall conform to ANSI Z129.1.
9.2 Technical data shall be provided for at least all data elements categorized as “essential” in SSPC-Guide 13.
10.1 All material supplied under this speciﬁcation is subject to timely inspection by the purchaser or an authorized representative. The contractor shall replace such material as is found defective under this speciﬁcation (see Notes 12.5 and 12.6). In case of dispute, unless otherwise speciﬁed, the arbitration or settlement procedure established in the procurement documents shall be followed. If no arbitration procedure is established, then a procedure mutually agreeable to the purchaser and material supplier shall be used.
10.2 Samples of paints may be requested by the purchaser and shall be supplied upon request, along with the manufacturerʼs name and identiﬁcation for the materials. Samples may be requested at the time the purchase order is placed, at pre-shipment, or may be taken from unopened containers at the job site.
10.3 Unless otherwise speciﬁed, the sampling shall be in accordance with ASTM D 3925.
11.1 While every precaution is taken to ensure that all information furnished in SSPC standards and speciﬁcations is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials,coatings, or method sspeciﬁed herein, or of the speciﬁcation or standard itself.
11.2 This speciﬁcation does not attempt to address problems concerning safety associated with its use. The user of this speciﬁcation, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all governmental regulations.
Notes are not requirements of this speciﬁcation.
12.1 The polyurea topcoat coatings currently used generally fall into one of the two categories listed below. Advantages of these coatings include: moderate or fast dry, even at low temperatures, high ﬁlm build, good abrasion and corrosion resistance, and good color and gloss retention. The dry time can vary from minutes to hours depending upon the formulation.
12.1.1 Hindered Aliphatic Polyureas (Type2 Moderate Cure): The properties of this type of polyurea include good color and gloss retention and controllable ﬁlm builds, pot lives, and dry times with application advantages using either conventional or plural spray equipment. Typical dry times (to handle) range from 30 minutes to 2 hours with dry ﬁlm thickness up to 15 mils per coat. Variable pot lives range from 30 minutes to 90 minutes.
12.1.2 Non-Hindered Aliphatic Polyureas (Type 1 Fast Cure): While having good color and gloss retention, the reaction rate of this type of polyurea is rapid with a short pot life that requires plural equipment for spray application and high ﬁlm build with very fast cure and dry characteristics.
12.2 HYBRID SYSTEMS: The coating may be modiﬁed with light-stable polyols, such as acrylics or polyesters, to form hybrid systems. Hybrid systems that meet the performance requirements of this speciﬁcation typically contain approximately 70% amine functional resins by weight solids of the non-isocyanateco-reactants. This 70% value is not a mandatory compositional requirement of this speciﬁcation but is offered as an informational guideline for formulation purposes.
12.3 GLOSS LEVELS: Typically, 60-degree specular gloss levels are identiﬁed as follows: Low Gloss – less than 30 Medium Gloss – 30 to 70 High Gloss – higher than 70
12.4 VOC CONTENT: Each coating, after recommended thinning, must conform to published government regulations regarding volatile organic compound (VOC) content. VOC information should be supplied on the label or the technical data sheet. Various governmental agencies may have different VOC limits or use different methods of testing. The owner may modify this speciﬁcation as necessary to specify a particular VOC content limit consistent with local regulations. Coatings meeting the composition and performance requirements of this speciﬁcation usually have a VOC level less than 3.5 lb/gal (420 g/L). Some of these coatings are near 100% solids and have almost no VOC content.
12.5 The procurement documents should establish the responsibility for samples, testing, and any required afﬁdavit certifying full compliance with the speciﬁcation.
12.6 QUALITY ASSURANCE TESTS: If the user chooses, tests may be used to determine the acceptability of a lot or batch of a qualiﬁed coating. The quality assurance tests are used to determine whether the supplied products are of the same type and quality as those originally tested and certiﬁed for acceptance. The selected tests should accurately and rapidly measure the physical and chemical characteristics of the coating necessary to verify that the supplied material is substantially the same as the previously accepted material. All of the quality assurance tests must be performed on the originally submitted qualiﬁcation sample. The results of these tests are used to establish pass/fail criteria for quality assurance testing of supplied products.
12.6.1 Establishing Quality Assurance Acceptance Criteria: Many ASTM test methods contain precision and bias statements. Speciﬁcation developers should be cognizant of the fact that these statements exist. Quality assurance test criteria should not be more stringent than the inter-laboratory precision of the test methods used.
Example: A common quality assurance test is density (weight per gallon) as measured by ASTM D 1475. The inter-laboratory reproducibility at the 95% conﬁdence level tells us that because of errors associated with the method, any two measurements of the same material can differ by as much as 1.8%, without the measurements being considered suspect.
This only represents the precision of the measurement technique and does not account for normal variances in the manufactured product.
The acceptable range for paint density must be stated. For example, a composition speciﬁcation may state this requirement as 10.0 ± 0.2 lb/gal, 10.0 lb/gal ± 2%, or as a range from 9.8 to 10.2 lb/gal. The manufacturer of proprietary products should provide this information. Using these values, if the manufacturer’s lab measures the density to be 9.8 lb/gal, the product meets the speciﬁcation and the paint is shipped to the job. Because of the lab to lab variation of 1.8%, the user’s lab may measure the density of this sample to be as low as 9.8 less 1.8% of 9.8 (equals 9.6) lb/gal. Similarly for the high end, the manufacturer may measure density of 10.2 lb/gal while the user measures 10.2 plus 1.8% of 10.2 (equals 10.4) lb/gal. The pass/fail criteria for the user to accept a batch of paint should therefore be 9.6 to 10.4 lb/gal.
Where precision and bias data are not available for a given test method, determine the standard deviation of a minimum of ﬁve measurements taken on the originally tested and certiﬁed material. The pass/fail criterion is that the measurement of the test sample shall fall within two standard deviations of the target value. The contracting parties must agree on a target value.
12.6.2 Recommended Quality Assurance Tests: Recommended quality assurance tests include but are not limited to, infrared analysis (ASTM D 2621), viscosity (ASTM D 562), weight per gallon (ASTM D 1475), total solids (ASTM D 2369), dry time (ASTM D 1640), percent pigment (ASTM D 2371), gloss (ASTM D 523), color (ASTM D 1535), condition in container (FED-STD-141, Method 3011), and odor (ASTM D 1296).
Appendix1: Optional Laboratory Physical Tests of Applied Films
Properties of polyurea topcoat vary with formulation for the intended use. When polyurea topcoats are tested for direct impact resistance in accordance with ASTM G 14, values typically range from 20 to 50 in-lb. When polyurea topcoats are tested in accordance with ASTM D 4060 (Taber abrasion using a CS 17 wheel and a 1000 g weight for 1000 cycles), values for loss typically fall between 80 and 140 mg. Speciﬁc values for the various types of polyurea coatings can be obtained from coating manufacturers for the purpose of deﬁning desired property requirements.
PAINT SPECIFICATION NO. 39 – Two-Component Aliphatic Polyurea Topcoat Fast or Moderate Drying, Performance-Based