SSPC: The Society for Protective Coatings Paint SPECIFICATION NO. 39 Two-Component Aliphatic Polyurea Topcoat Fast or

• Scope

• This specification contains performance require-ments for a two-component, weatherable polyurea topcoat. The coating may be fast or moderately fast drying (see Note 12.1).

• Coatings 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), and 2B (frequently wet by salt water, 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.

• The specified coating is intended for application by single-component airless spray, electrostatic spray, or plural-component equipment, depending upon its formulation.

• This coating is intended for use as a topcoat over suitably primed ferrous metal and cementitious substrates.

• Description

• 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.

• COATING TYPE: The two types of polyurea coat-ings are differentiated by drying time.

• Type 1 (Fast Drying): A Type 1 coating dries to handle in less than 30 minutes (per ASTM D 1640).

• Type 2 (Moderate Drying): A Type 2 coating dries 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 speci-fier 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 speci-fied, Level 3A for accelerated weathering (longest accelerated exposure) will be assumed.

• Level 1A: Level 1A coatings have been evaluated for 500 hours in accelerated weathering testing.

• Level 2A: Level 2A coatings have been evaluated for 1000 hours in accelerated weathering testing.

• Level 3A: Level 3A coatings have been evaluated for 2000 hours in accelerated weathering testing.

• Level 1N: Level 1N coatings have been evaluated for 12 months in natural exterior weathering testing.

• 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 proper-ties 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 neces-sary to establish their color and gloss retentive properties.

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• Referenced Standards

• The latest issue, revision, or amendment of the refer-enced 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.

• 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.

• SSPC STANDARDS:

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:2

Z129.1 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 Testing3

• Method 3011 Condition in Container Method 4331 Spraying Properties

• Composition

• This is a performance-based coating specification, therefore the manufacturer is given wide latitude in the selection of materials and manufacturing processes (see Note 12.4).

• RESIN REQUIREMENT: The reactive 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).

• Standard Testing Conditions

• 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.

• APPLICATION: In accordance with the manufac-turer’s written recommendations, the topcoat shall be spray-applied in a single coat or multiple coats.

• 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 recom-mended film thickness, then the minimum DFT shall be 150

• ASTM, 100 Barr Harbor Road, West Conshohocken PA, 19248, (http://www.astm.org).

• ANSI, 1819 L Street, NW, Washington, DC 20036, (http://www.ansi.org).

• FED-STD 141 may be obtained from http://assist.daps.dla.mil.

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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.

• 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

• 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.

• Requirements of Liquid Coating

• APPLICATION PROPERTIES: All guidance provided by the manufacturer regarding mixing of multi-compo-nent products, thinning requirements, and special application requirements shall be followed. The coating shall be easily applied by spray when tested in accordance with FED-STD-141, Method 4331. The paint shall show no streaking, running, or sagging during application or while drying.

• 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 consis-tency of greater than 10 Krebs units or noncompliance with the application requirements shall be cause for rejection.

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• 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).

• 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).

• 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.

• 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.

• Physical Tests of Applied Films

• 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 appli-cable

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.

7.3.2 A Type 2 topcoat must be dry in 30 minutes to 2 hours.

• Weathering Requirements

• 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 wh 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

4 The 30-day cure requirement is based on obtaining optimal mechanical properties that may be required by some specifiers.

• 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 testing defined in Section 5.3 based on field experience of committee personnel and examination of other referenced standards that have with-stood the test of time. ASTM D 5144-97, para 8.1.1 “Standard Guide for Use of Protective Coatings in Nuclear Power Plants” and ANSI N5.12-1973, para 6.4 “Protective Coatings (Paints) for the Nuclear Industry” both call for minimum adhesion values of 1.4 MPa (200 psi). The minimum recoatability adhesion value of 4.1 MPa (600 psi) specified herein is a substantial increase over the stringent requirements of coatings for nuclear service.

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TABLE 1

SUMMARY OF PERFORMANCE TESTING RESULTS TO BE REPORTED

• Smaller values of color change (less than 2.0 E*) may be visible to the eye, but the noticeable change maximum of 3.0 E* specified herein is deemed acceptable for most industrial and marine applications. More stringent gloss and color retention requirements should be specified as needed.⁶
• These values do not apply to deep tones and safety colors.

• Either outdoor or accelerated testing will fulfill the requirements of this standard. The user must stipulate the type of testing to be used. Both tests are not required unless specified.

• South Florida testing is ongoing. 24-month testing was completed in July 2003 and testing is continuing to obtain 48-month data.

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.

• Level 1A: Products conforming to this performance level shall have a maximum gloss reduction of 20% and maximum color change of 2.0 ∆E* per ASTM D 2244 after 500 hours expo-sure.

• Level 2A: Products conforming to this performance level shall have a maximum gloss reduction of 30% and maximum color change of 3.0 ∆E* after 1000 hours exposure.

• Level 3A: Products conforming to this performance level shall have a maximum gloss change of 40% and a maximum color change of 3.0 ∆E* after 2000 hours exposure.

• The maximum allowable gloss reduction and color change levels for accelerated UV-A/Condensation and Florida exposure were derived from committee consensus, notably by resin and coating manufacturers and users who have field and laboratory experience and have actively participated on the SSPC Polyurethane Coatings Committee.

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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.

• Level 1N: Products conforming to this perfor-mance level shall have a maximum gloss change of 35% and a maximum color change of 2.0 ∆E* after a 12-month exposure.

• Level 2N: Products conforming to this perfor-mance level shall have a maximum gloss change of 50% and a maximum color change of 3.0 ∆E* after a 24-month exposure.

• Labeling

• Labeling shall conform to ANSI Z129.1.

• Technical data shall be provided for at least all data elements categorized as “essential” in SSPC-Guide 13.

• Inspection

• 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 procure-ment 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 manufacturer’s 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.

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• Disclaimer

• 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 methods specified herein, or of the specification or standard itself.

• This specification does not attempt to address prob-lems 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

Notes are not requirements of this specification.

12.1 The polyurea 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 Hindered7 Aliphatic Polyureas (Type 2, 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 reac-

tion 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 approxi-mately 70% amine functional resins by weight solids of the non-isocyanate co-reactants. This 70% value is not a mandatory compositional requirement of this specification but is offered as an informational guideline for formulation purposes.

• The term “hindered” refers to the use of a certain type of amino reagent that tempers and retards the fast reactivity rate with an isocyanate co-reactant during the formation of a polyurea polymer.