{"id":8059,"date":"2018-04-27T08:00:25","date_gmt":"2018-04-27T14:00:25","guid":{"rendered":"https:\/\/www.ulprospector.com\/knowledge\/?p=8059"},"modified":"2018-05-04T10:04:19","modified_gmt":"2018-05-04T16:04:19","slug":"pc-new-coatings-require-new-equipment-and-testing","status":"publish","type":"post","link":"https:\/\/ulprospector.ul.com\/8059\/pc-new-coatings-require-new-equipment-and-testing\/","title":{"rendered":"Passing the Test: New Coatings Require New Equipment and Testing"},"content":{"rendered":"

\"InnovationsThey say that \u201cnecessity is the mother of invention.\u201d This is true in coatings, not only in formulation but also in testing. Products are developed to fill a need, but how do you know you have achieved the properties required if tests for those key performance indicators don\u2019t exist?<\/p>\n

As an established example, we have elastomeric coatings. The first acrylic-based resins for roof coatings were formulated into paints around 1975. These resins were somewhat similar to ones used in caulks, at least in their flexibility, adhesion, water and weather resistance. As more and more paint companies developed products, it became very difficult for architects, specifiers and contractors to distinguish among acrylic roof coating products.1<\/sup><\/p>\n

In 1995, under the Roofing and Waterproofing Committee, D08 developed ASTM D6083, which is entitled \u201cStandard Specification for Liquid Applied Acrylic Coating Used In Roofing.\u201d Most of the tests cited as part of the standard exist from other standards. However, some were developed, in that there wasn\u2019t any way to evaluate specific properties, such as adhesion to various substrates. The ASTM D6083 specification employs either the ASTM C794 or D903 method for measuring peel adhesion, which was the result of a lot of laboratory work in the Springhouse facility of Rohm & Haas.<\/p>\n

\"Paint
Figure 1 – Sprayed polyurethane foam (SPF) adhesive failure (bottom). Peel test with cloth strip<\/figcaption><\/figure>\n

More recently, many new products and testing have been developed in tandem, to differentiate improvements to the products. Several cases are provided herein, citing ASTM standards. In most cases, there are similar standardized tests from DIN, SAE and other governing bodies.<\/p>\n

Scratch-resistant coatings<\/strong> for optical wear have been available for many years. Prior to their development, there had been many tests for resistance to chipping, scratching, etc. including ASTM D-0968-05, D4060-10, D6037-96 and others. These are all too harsh for plastics such as polycarbonate, polymethylmethacrylate, CR-39\u2122and Trivex\u2122, as well as coatings on plastics. Hence, several tests were developed, which include the Bayer Abrasion test (ASTM F735-81)2<\/sup>, Steel Wool Abrasion and others3<\/sup>. Instruments to qualitatively measure the reduction in optical clarity (haze) were developed along with the test methods.4<\/sup><\/p>\n

Recently, fingerprint transfer resistance<\/strong> has become a much-desired property for electronic devices with screens, as well as for appliances, where stainless steel and glossy black finishes have become popular. Again, to evaluate performance, one must have a reliable, reproducible and quantitative test method. Daikin America has developed a test method to evaluate the resistance to fingerprint transfer.<\/p>\n

As indicated in Optool DSX literature,5<\/sup> the fingerprint is transferred and then a Kimwipe is used with a standard force, to test ease-of-removal.<\/p>\n

\"Optool
Figure 2 – Optool DSX evaluation. SOURCE: Daikin America<\/figcaption><\/figure>\n

With the proliferation of wind turbines<\/strong> came the realization that the leading egde of the blades experienced erosion similarly to those on fixed wing and rotary aircraft. However, unlike the latter which can be addressed relatively easily, onshore blades that are 45M long, attached to a turbine\u2019s hub 80M off the ground, are very difficult to overhaul. In addition, downtime taking that unit out of service results in lost power and revenue. There are existing rain erosion tests that have been used for aircraft, but no test is available to evaluate ice accretion and shedding, which are additional issues with wind turbine blades.<\/p>\n

There are several laboaratories that have since developed test methods and equipment to appraise ice accretion and release from coatings systems. The United States Corp of Army Engineers runs the Cold Regions Research and Engineering Laboratory (CRREL).<\/p>\n

\"CRREL
Figure 3 – CRREL Test Equipment<\/figcaption><\/figure>\n

The aluminum cylinders are spray-coated with material, and then the coated cylinders are frozen into an ice mold. The sample is placed in a fixture and a load applied, so the failure stress (kPa) can be measured. Although a good test, there is a fair amount of variability and therefore reproducibility is a challenge.<\/p>\n

Fraunhofer Institute (IFAM) has developed an Icing Chamber to simulate the conditions of freezing rain or mist in sub-zero temperatures.<\/p>\n

\"Fraunhofer
Figure 6: Fraunhofer Institute (IFAM) Icing Chamber. SOURCE: Fraunhofer IFAM<\/a><\/figcaption><\/figure>\n

The Chamber mimics most conditions which include frost adhesion, ice-rain and runback ice test, where the ice moves along the blade as it is formed. It can test ice accretion, as well as cyclical melting and reformation of ice. Their system also utilizes Dynamin Differential Calorimetry to investigate the freezing point depression caused by funtional surfaces. Through the use of these new test methods, patents have been developed based on quantiative data collected during development.6<\/sup><\/p>\n

There are other examples of tests and equipment developed to evaluate coatings formulations in new markets. Dry time for fast-dry traffic paints is just one additional one. Many new ASTM tests have been developed for new products, applications and markets, as well as solventborne coatings, but have been deemed inappropriate for their waterborne counterparts.<\/p>\n

In summary, all of the tests cited were developed as a result of a need to quantify performance to differentiate changes in formulations. They almost always mirror an actual condition that exists, but in a way that is reproducible, can be performed in a laboratory setting, and in a much shorter time frame than occurs naturally.<\/p>\n

Further reading:<\/h3>\n