Blocking resistance, testing

For each oven taiperature setting, the residence recruized to produce a "cured" coating was determined. "Cure" was determined by a block resistance test. Ttoo coated board samples exiting frcm the oven were allowed to cool to 66°C and then pressed together face-to-face in a heated press (66°Cl set at a pressure of 80 psi. After 10 minutes, the boards were ranoved from the press and separated frcm one another. The coatings were considered "cured" if no blocking occurred. 

Block resistance - wet/dry - ink to ink and ink to substrate The exposure time, pressure, and temperature are specified by the end use requirement (i.e. 3 min at 1034 bar, 50 °C for surface print ink (5.4) - The ink surface s resistance to heat and pressure is subjectively measured. Ink properties that effect blocking results are hardness , adhesion, cohesion, and slip. The polymer glass transition temperature (Tg), molecular weight, and surface compatibility effect the block resistance test... 

Using this equation, the approximate (T — T ) value required for a film of a thermoplastic copolymer to be dry-to-touch, ie, to have a viscosity of 10 mPa-s(=cP), can be estimated (3,4). The calculated (T — T ) for this viscosity is 54°C, which, for a film to be dry-to-touch at 25°C, corresponds to a T value of —29 "C. The calculated T necessary for block resistance at 1.4 kg/cm for two seconds and 25°C, ie, rj = 10 ° mPa(=cP), is 4°C. Because the universal constants in the WLF equation are only approximations, the T values are estimates of the T requited. However, if parameters such as the mass per area appHed for blocking were larger, the time longer, or the test temperature higher, the T of the coating would also have to be higher. 

Determination of Heat Liberated on Explosion with Calorimeter (99-104) Lead Block Expansion Test (Trauzl Test) (104-06) Compression Tests with Small Lead Blocks (106-08) Testing of Detonators, which include Sand Test and Nail Test (108-14) Water Resistance of Electric Detonators (114-15) Testing Burning (Safety) Fuse (115-18) Testing Detonating Fuse (118-19)... 

Detailed resistance tests against decay fungi and termites have been conducted on epoxide-treated wood. Brown-rot fungi, L. lepideus and G. tra-beum, yielded 44.2% and 62.9% weight loss (WL) of control southern pine, respectively, after 12-week soil block tests. 

Some PAL Inhibitors (especially AOA and AOPP) have been used to test the role of PAL In disease resistance. These PAL Inhibitors did not block resistance expression or glyceollln accumulation In soybean tissue treated with an Incompatible race of PhvtoDhthora meoasoerma... 

Bonding of chemicals to wood cell wall components--cellulose, hemicellulose and lignin—can change the physical and chemical properties of the wood. For example, reaction of southern pine with simple epoxides results in a modified wood which is resistant to attack by subterranean termites in laboratory tests (1). Wood modified with acetic anhydride, dimethyl sulfate, 0-propiolactone and epoxides are highly resistant to attack by microorganisms in standard soil block laboratory tests (2,3). Southern pine modified by reaction with acetic anhydride and propylene and butylene oxides has a reduced tendency to swell in the presence of water (4). 

Blocking test n. Procedure for determining the tendency of painted surfaces to stick together (block) when stacked or placedin contact with each other under a weighted load. See block resistance. 

Antiblock performance was tested, yielding a large number of quantified information. The ASTM standards were used to determine the coefficient of friction and blocking resistance. This research shows that the methods are very useful and have sufficient precision for research studies. 

AS 4878.11-2001 Methods of test for coated fabrics - Determination of blocking resistance. 

NF EN 25978 1993 Rubber- Or plastics-coated fabrics. Determination of blocking resistance. ASTM D3702-94(2009) Standard Test Method for Wear Rate and Coefficient of Friction of Materials in Self-Lubricated Rubbing Contact Using a Thrust Washer Testing Machine. 

ASTM D3003-01(2012) Standard Test Method for Pressure Mottling and Blocking Resistance of Organic Coatings on Metal Substrates. 

AS 1580.409.3-2002 Paints and related materials - Methods of test - Blocking resistance of latex paint finishes. 

ASTM D918-99(2008) Standard Test Mettiod for Blocking Resistance of Paper and... 

D-3024. Specification for Protein-Base Adhesives for Structural Laminated Wood Products for Use Under Interior (Diy Use) Exposure Conditions. Employs the D-0>905 block shear, D-0906 plywood shear, and D-4300 mold resistance tests to evaluate mostly casein-base adhesives for use in interior grade laminated beams. 

This test was developed to determine the tear resistance of foam. The tear-resistance test, also known as the block method, uses the block specimen described in Figure 14-7. The block specimen is mounted by spreading the block so that each tab is held in the jaw of the tensile testing machine. The load is applied by separating the jaws at a specified speed. The force required to rupture the specimen is recorded. The tear resistance is calculated from the maximum load recorded and the average thickness of the specimen. The tear resistance is reported in newtons per meter. 

Figure 14-7. Block specimen—tear resistance test. (Reprinted with permission of ASTM.)...

D 2793-69 Test Method for Block Resistance of Organic Coatings and Wood Substrates. 

D 4946-89 Test Method for Blocking Resistance of Architectural Paints. 

ASTM D4946-89(2003) Standard Test Method for Blocking Resistance of Architectural Paints. ISO 15741 2001 Paints and varnishes — Friction-reduction coatings for the interior of on-and offshore steel pipelines for non-corrosive gases. 

The over-washing test is performed on holes perforate reference block defined in standard NFA 09.521 and permits the evaluation of the resistance to over-washing of penetrants (see figure 2, annex 1). 

The characteristics of interior paints that require testing and analysis include hiding and appearance, package stabiHty, adhesion, spatter resistance, flow and leveling, color and sheen uniformity, touch-up, stain removal, burnish resistance, and block and print resistance. A popular test that assesses the wet abrasion resistance of an interior paint is to measure its scmb resistance. A mechanical device is used to scmb a paint film of a specified thickness with a standard bmsh and abrasive cleanser suspension. The number of scmb cycles (back and forth movements of the weighted bmsh) at various end points (first cut through, or 50% removal of the film) is then recorded. Scmb resistance usually holds steady or decreases slightly as PVC is increased, but drops quickly once the CPVC is exceeded in a paint formulation. 

Due to the polyether blocks, these polymers retain their flexibility down to about -40°C and only Grade 6333 breaks in an Izod test at this temperature (using specimens of thickness 3.2 mm). The materials generally show excellent resistance to crack growth from a notch during flexure some grades are reported... 

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