Blocking resistance

In addition to polyamide, lamination inks ordinarily contain modifiers such as polyketone resin, plasticizer, and wax to impart specific properties such as block resistance and increased bond strength. Because laminating inks are usually reverse-side printed and end-up sandwiched between films, gloss is not a primary requirement. Water-base laminating inks that will meet the U.S. EPA emission requirements and have the correct functional properties are currently under development. 

Increased water resistance Increased tensile strength Increased block resistance Increased solvent resistance Increased adhesion to hydrophilic surfaces... 

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. 

Both EVA and PE-based adhesives are commonly used for bags. EVA-based formulas typically use lower levels of VA ( 18%) compared to case and carton adhesives to improve heat and blocking resistance. For both EVA and PE adhesives high levels of polymer (45-75%) are used for maximum strength. Adhesion is generally better and blocking slightly worse for EVA vs. PE. 

The resistor (R1) is used to control the capacitor. The first diode (D1) can be either a single diode (halfwave rectified) or a bridge rectifier. The second diode (D2) is to protect the capacitor from the HV spike from the coil and should be large enough to provide blocking resistance to this spike. The third diode (D3) similarly prevents the capacitance discharge from flowing back to the coil. 

Post-crosslinkable and substrate reactive polymers are widely used to Improve water and solvent resistance, strength, substrate adhesion and block resistance In binders, adhesives and coatings. The surprisingly rich chemistry of a new class of functional monomers (eg. 1 and 2) related to standard amide/aldehyde (amlnoplast) condensates, but which eliminate aldehyde emissions, was elucidated by monomeric model and mechanistic studies and discussed In the preceeding paper (1). Results with these monomers In copolymer systems are reported here. 

These comprise components A to C, the amount of component B being 5 to 50 pbw per 100 pbw of A (based on solid content) and the amount of C being 50 to 350 pbw per 100 pbw of A (based on solid content). A is an emulsion of ethylene-vinyl ester copolymer, which is composed of 5 to 35 wt.% of ethylene and 95 to 65 wt.% of vinyl ester, and has a Tg of -25 to -I-15C and a toluene-insoluble part of 30 wt.% or more. B is a thermal expansive hollow microbead and C is an inorganic filler. The emulsion has superior mechanical strength, crack resistance, water resistance, alkali resistance, blocking resistance, foaming property, embossing property and superior flame resistance and can be used for flameproof foam sheet for wallpaper. 

By contrast, conventional, nonreactive surfactants, apart from water uptake and the resulting drawbacks, may cause a permanent reduction in surface hardness, poor blocking resistance, inferior sandability and dirt pick-up. These effects were already observed by Van-derhoff in the early 1950s and were confirmed more recently by Hellgren et al. using the atomic force microscopy (AFM) technology [13]. 

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. 

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... 

FIGURE 12.4 Schematic cross section of a wafer with block resist-RIE for non-CMP planarization before (above) and after RIE (below). 

Cohesives are essentially contact adhesives. Cohesives are water borne products typically formulated with natural rubber latex polymers modified with other polymers such as acrylics and acetate polymers to yield the necessary peel and block resistant properties. Cohesives are used for a wide variety of applications on various paper products and films particularly for confectionery packaging. 

On elongation in the direction of the large arrows, the hard blocks resist deformation and the soft segments extend. On release of the stress, the original dimensions are recovered. 

Solid dimer polyamides used as vehicles for flexographic inks (14, 24) possess the required alcohol solubility to make it possible to use them on presses with rubber rolls. Their adhesion to films such as polyethylene, Saran, and Mylar is excellent, and their flexibility ensures that they will function properly on these flexible substrates. In addition, they have excellent gloss and good blocking resistance. Thus, they are commonly used on polyolefin, Saran, cellophane. Mylar, cellulose acetate, and PVC films. 

Epotal 181 D. [BASF AG] Ethylene polymer dispersion additive to other dispersions improves slip, blocking resistance, and hydrophobic pn ierties of film in paper finishing, adhesives. 

Pi with 0.01-10 phr PSP solution cast for films with good blocking resistance Mitsubishi Chem., 1984... 

ISO 5978. 1990. Rubber and plastics coated fabrics—Determination of blocking resistance. 

Slip agents, block resistance Silicone waxes... 

Uses Acrylic offering blocking resist, in exterior semi-gloss architectural coatings... 

Features Exc. low temp, film formation exc. scrub resist. good blocking resist., freeze/thaw stability exc. aging chars., water resist., flexibility Properties Milky wh. emulsion 0.5 p avg. particle size si. odor dens. 9.0 Ib/gal vise. 200-600 cps pH 4.8-5.5 nonionic 55% solids Airflex 4500 [Air Prods./Poiymers]... 

Uses Urethane for aq. parquet coatings, air- and force-drying primer surfacers for aufomofive refinishing additive resin to improve drying, hardness, and blocking resist, of aq. coatings Features Compat. with acrylic disps., other PU disps., water-thinnable polyesters and amino resins... 

Uses Acrylic for fast drying lacquers for wood finishing applies. Features Hard emulsion exc. print and block resist. very good stain and water resist. designed to replace traditional nitrocellulose lacquers and varnishes produces sealers with exc. sandability and min. grain raising Properties Ott-wh. translucent emulsion dens. 8.6 Ib/gal vise. 40 cps pH 8.0 hardness (Konig) 51 41.5% NV by wt. 

Features Very hard emulsion where block resist, and economy are important exc. compat. with waterborne alkyds Properties Mill wh. emubion dens. 8.5 Ib/gal vise. 80 cps pH 8.0 hardness (Konig) 72 41.5% NV by wt. 

Uses Vehicle for clear coatings on paper, paperboard, and other board coating applios. inks and overprint varnishes Features Heat resist. good block resist, and heat resist, to 450 F Properties Dens. 8.9 Ib/gal vise. 600 cps pH 8.7 hardness (Konig) 38 42%NVbywt,... 

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