Tacky layer

Jap. Kokai Tokkyo Koho J 56120-786 1981 Hitachi Photocuring PSA sheet comprises tacky layer containing (meth)acrylic ester photopolymerization initiator and accelerator. 

The force of particle adhesion will depend on the depth to which the particles are embedded in the oil layer this in turn is determined by the particle precipitation velocity. Here the forces of adhesion will naturally be different for flat and spherical surfaces in the adhesion of two flat bodies separated by a tacky interlayer, the contact area is constant but when particles touch a tacky layer, the contact area may increase during the time in which the particle is becoming embedded in this layer. 

Simple addition of silanes to a rubbery polymer latex cannot impart water-resistant bonds to a mineral unless the silane deposits a resinous or tacky layer at the interface. A silane-modified resin or plasticizer will be effective if it can be retained as a separate phase in the emulsion and deposited as a primer layer on the mineral. 

In addition to this, the adhesion of a particle to a solid substrate covered with a tacky layer depends on the kinetic energy of the dust particle at the instant at which it comes into contact with the substrate (Fig. III.21). 

We see from Fig. III.21 that the adhesive force on the particles depends on the depth of penetration of the particle into the oil layer, which in turn is determined by the settling velocity of the particles. The adhesive forces will naturally be different for plane and spherical surfaces, since, in the sticking of two plane solids separated by a tacky layer the contact area is constant. 

In view of the absence of published data regarding the mechanism underlying the behavior of a tacky layer in the capture of dust, we must at present confine attention to qualitative considerations. It should be noted that the property of tackiness is used for the trapping of dust particles in self-cleaning oil filters, rou -cleaning automobile antidust filters. Rank filters made of metallic mesh, settling plates in konimeters, impactors, and similar apparatus [162]. In addition to this, adhesion to... 

The dry-processed, peel-apart system (Fig. 8b) used for negative surprint apphcations (39,44) is analogous to the peel-apart system described for the oveday proofing apphcation (see Fig. 7) except that the photopolymer layer does not contain added colorant. The same steps ate requited to produce the image. The peel-apart system rehes on the adhesion balance that results after each exposure and coversheet removal of the sequentially laminated layer. Each peel step is followed by the apphcation of the appropriate process-colored toners on a tacky adhesive to produce the image from the negative separations. The mechanism of the peel-apart process has been described in a viscoelastic model (45—51) and is shown in Figure 8c. 

In contact adhesives, the so-called tack open time is important. This can be defined as the time available after the adhesive is applied during which the surface remains tacky enough for the application of the adherend. It can be easily measured by applying a thin layer of fresh adhesive on Kraft paper and making a bond at different times until no bond is obtained. 

This mbber is very tacky in nature and contains acrylic group, which makes it polar in nature. Nanocomposites have been prepared based on this elastomer with a wide range of nanohllers. Layered silicates [53-55] have been used for this preparation. Sol-gel method [56,57], in situ polymerization [58], and nanocomposites based on different clays like bentonite [59] and mica [60] have been described. The mechanical, rheological, and morphological behaviors have been investigated thoroughly. 

The tacky polymeric microspheres that comprise the pressure-sensitive adhesive layers of repositionable notes are patented inventions. One such material (U.S. Patent 5,714,237) is prepared by a free-radical polymerization reaction of isooctyl acrylate (Fig. 14.3.1) in the presence of polyacrylic acid with a chain-... 

The main property that distinguishes a pressure-sensitive adhesive from other types of adhesives is that it exhibits a permanent and controlled tack. This tackiness is what causes the adhesive to adhere instantly when it is pressed against a substrate. After it has adhered, the PSA should exhibit tack, peel and shear properties that are reproducible within narrow limits. This requires that the adhesive layer be only slightly cross-linked.113 PSAs are based on polymers with low Tg, typically in the range-74 to +13°C.114... 

Tack - The property of a polymer, compound, or adhesive that causes two layers to stick together on application of mild pressure. Tacky polymers or compounds do not necessarily stick to other surfaces. 

Drying Properties.—Heavy resin oils have drying properties when spread in a thin layer on a strip of glass and kept at 50° for 74 hours, they thicken appreciably and become very tacky. 

Primers are applied quickly after surface preparation and result in a dry or slightly tacky film. It is generally recommended that they have a dried coating thickness range of tenths of a mil to approximately 2 mils. It is necessary to control the primer thickness, since if the primer layer becomes too thick, its bulk properties may predominate, and the primer could become the weakest part of the joint. 

Pressure-sensitive adhesives are used for labelling applications. They are permanently tacky and adhere to the surface of the desired substrate under pressure. A paper or plastic film label is coated with a pressure-sensitive adhesive and applied to a backing layer - usually siliconised paper from which the label can be removed easily. The labels are then printed and sent... 

The main use of adhesives in labelling applications is in the form of pressure-sensitives, i.e., sticky labels attached either directly or indirectly (behind a potential barrier layer) to a foodstuff. Pressure-sensitive adhesives are a distinct category of adhesives that in dry form are permanently tacky at room temperature. These adhesives will adhere to a variety of substrates when applied with pressure they do not require activation by water, heat or solvents and they have sufficient cohesive strength to be handled with the fingers or by mechanical means in labelling stations. 

All specimens were made from IM7/977-2 prepreg supplied by Cytec. One single panel, 300 mm X 750 mm was laid up by hand on a warm table because the prepreg was not particularly tacky. Hot de-bulks (vacuum only, 60 C) were carried out after every fourth layer. A 10 p.m FIFE film was inserted in the mid-plane of the laminate in order to simulate an artificial crack. A final pressurised de-bulk (120 C, 3 bar pressure, 30 minutes) was carried out in order to reach a laminate thickness close to neat cured thickness, prior to Z-pinning with 0.28 mm diameter pins (T600/BMI), at densities of 0.5%, 2% and 4% in the selected locations. Table 1 summarises the range of specimens made. 

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