SSPC: The Society for Protective Coatings
Paint SPECIFICATION NO. 39
Two-Component Aliphatic Polyurea Topcoat
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.
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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|Guide 13||Guide for the Identification and Use|
|of Industrial Coating Materials in|
|PA 2||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
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
FED-STD-141: Paint, Varnish, Lacquer and Related
Materials: Methods of Inspection, Sampling
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.
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7.3.1 A Type 1 topcoat must be dry in less than 30 minutes.
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.
4 The 30-day cure requirement is based on obtaining optimal mechanical properties that may be required by some specifiers.
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SUMMARY OF PERFORMANCE TESTING RESULTS TO BE REPORTED
|Color Retention per||Maximum Gloss|
|ASTM D 2244||Reduction from Original|
|Performance||(Color change in||Reading per|
|Exposure Test||Level||Exposure Time||E*)(a)||ASTM D 523|
|Accelerated||Level 1A||500 h||2.0||20%|
|Weathering (c)||Level 2A||1000 h||3.0||30%|
|(ASTM D 4587,|
|Cycle 2)||Level 3A||2000 h||3.0||40%|
|South Florida||Level 1N||12 mo||2.0||35%|
|Level 2N||24 mo(d)||3.0||50%|
|(ASTM D 1014)|
|Solvent resistance (ASTM D 5402)|
|100 double rubs with MEK||no visible topcoat on cloth|
|Avg. of 3 pulls 4.1 MPa (600 psi)|
|Pull-Off Adhesion (ASTM D 4541, Type III or IV)||2 pulls, each 4.1 MPa (600 psi)|
|All pulls 3.4 MPa (500 psi)|
|Dry-Through (or Dry-To-Handle) Time (ASTM D 1640)||Type 1||less than 30 minutes|
|Type 2||30 minutes to 2 hours|
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.
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.
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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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.
Fast or Moderate Drying, Performance-Based