Tack of pressure-sensitive adhesives

D 3121 Test Method for Tack of Pressure Sensitive Adhesives by Rolling Ball... 

ASTM D3121 -94 (1999) Standard test method for tack of pressure-sensitive adhesives by rolling ball. 

Pressure Sensitive Tadc of Adhesives Using an Inverted Probe Machine, Test for (D 2979) Tack of Pressure-Sensitive Adhesives by Rolling Ball, Tbst for [Pg.790]

Figure 14. Standard test methods fiat the tack of pressure-sensitive adhesive tapes A) Rolling-ball tack B) Rotating-drura tack ...

Zosel, A. (1997). The Effect of Bond Formation on the Tack of Polymers. Journal of Adhesion Science and Technology, Vol. 11, No. 11, pp. 1447-1457, ISSN 0169-4243 Zosel, A. (1998). The Effect of Fibrilation on the Tack of Pressure Sensitive Adhesives. International Journal of Adhesion Adhesives, Vol. 18, pp. 265-271, ISSN 0143-7496... 

Zosel, A., Fracture energy and tack of pressure sensitive adhesives. Adv. Press. Sens. Adhes. TechnoL, 1, 92-127 (1992). 

Tack of pressure-sensitive adhesives We will study pressure-sensitive adhesives in a special chapter later in Volume 4. 

Illustrations of several test methods used to characterize tack of pressure-sensitive adhesives (PSAs) (a) flat probe tack, (b) loop tack, and (c) rolling ball tack... 

Zosel A (1998) Effect of fibrillation on the tack of pressure sensitive adhesives. Int J Adhes Adhes 18(Compendex) 265... 

Resins are used to improve the tack of pressure sensitive adhesives. They must be compatible with the polymer (i.e. mixture has a single Tg) and modify its viscoelastic properties resulting in improved polymer flow characteristics, substrate wetting, and adhesive bond formation. 

In another tack test, a steel ball of specified diameter is rolled down a grooved incline onto a conditioned surface area of pressure sensitive adhesive (ASTM D 3121, PSTC-6). The length of travel before it stops is the rolling ball tack (Fig. 2d) reported in millimeters. It is relatively inexpensive and simple to set up. Similar test variables to the probe tack test apply. 

In the earlier art, there was some consideration that partial incompatibility of the tackifier resin with the rubber was responsible for the appearance of tack, but this no longer is seriously held in light of continuing studies by many investigators. Aubrey [38] has addressed this in his review of the mechanism of tackification and the viscoelastic nature of pressure sensitive adhesives. Chu [39] uses the extent of modulus depression with added tackifier as a measure of compatibility. Thus in a plot of modulus vs. tackifier concentration, the resin that produces the deepest minimum is the most compatible. On this basis, Chu rates the following resins in order of compatibility for natural rubber rosin ester > C-5 resin > a-pinene resin > p-pinene resin > aromatic resin. 

Because of the unique properties of pressure-sensitive adhesives, special tests not applicable to other types have been developed. While standard physical tests such as nonvolatile content, viscosity, and specific gravity are performed to ensure consistency of application, these tests do not predict adhesive performance. For pressure-sensitive adhesives, three critical performance characteristics are usually measured tack, peel, and shear strength. 

The fourth and fifth papers have to do with properties of pressure-sensitive adhesives. In particular, the matter of how the materials composing pressure-sensitive adhesives (rubbers and resins) interact and phase separate to produce the phenomenon of tack or pressure-sensitivity is addressed. Both studies use dynamic mechanical measurements to uncover phasing - one in a silicone and the other in natural and styrene-butadiene rubber systems tackified with various resins. 

Recent reviews of the basis of tack have been presented by Wool and, in the context of Pressure-sensitive adhesives, by Creton and Fabre. ... 

The maximum tack properties of pressure-sensitive adhesive appear to occur when the room-temperature modulus falls within the range 5 X 10 to 1 X 10 dyn/cm and the glass transition temperature is within the range of —10 to 10°C. Figures 34-40 are plots of adhesive properties vs. resin concentration for two rubbers (SBR and NR) with various resins. It is seen in Figures 32, 33, and 41 that the adhesives show optimum tack and peel properties at the resin loading which has a minimum G (25°C) value (about 40-60% loading). 

Tack property of a material that enables it to form a bond immediately on contact with another surface, which can be an adherent or another layer of adhesive. High tack is particularly important in the case of pressure-sensitive adhesives (tapes, labels), for which it is even measured. Tack is generally difficult to measure in setting adhesives. 

Hammond, F.H., Tack. In D. Satas (Ed.), Handbook of Pressure Sensitive Adhesive Technology, Vol. 1. Van Nostrand Reinhold, New York, 1989, pp. 38-60. 

Two important parameters in the formulation of pressure sensitive adhesives are tack and hold, which is the ability to resist creep under deadload. As noted, butyl and polyisobutylene are inherently tacky polymers. This tack can be enhanced with a wide variety of resins and other tackifiers. The hold or cohesive strength is low compared to some other pressure sensitive adhesive polymers, such as natural rubber, but can be increased if required by (1) incorporation of high molecular weight PIB or natural rubber, (2) the choice of the other ingredients, particularly resins and fillers, and (3) the partial or preferential curing techniques noted previously. The poly isobutylene polymers are primarily used in label pressure sensitive adhesives and in certain tapes where high cohesive strength is not necessary. 

Tack loss occurring during aging of pressure-sensitive adhesives has been traced in some cases to the hydration of ester-type resins in the formulation. Therefore, in case of a tack loss problem, it should be determined whether the loss is oxidative or due to moisture pickup. Where hydration occurs, control of water pickup during manufacture or storage, change in resin type, or the removal of the moisture in a vacuum oven are possible solutions. 

The Pressure Sensitive Tape Council has developed a series of test procedures for the determination of tack, adhesion, and shear properties of pressure sensitive adhesives. The most commonly used tests are ... 

Abstract The basic concepts, formulations, and test methods of pressure-sensitive adhesives are presented. The importance of interfacial interactions, viscous loss, and extensibility are stressed. The common rheological tests are described and the equivalence of deformation rate and test temperature is emphasized. The much longer time scale for bond formation versus the rate of deformation upon debonding in peel or tack is exploited by the formulator to optimize properties. The formulation principles and common ingredients for preparing acrylic- and rubber-based adhesives are described, and the performance capabilities of these two types of pressure-sensitive adhesives are contrasted. 

Christensen SF, Everland H, Hassager O, AJmdal K (1998) Observations of peeling of a polyisobutylene-based pressure-sensitive adhesive. Int J Adhes Adhes 18 131 Creton C, Shull KR (2009) Probe Tack. In Benedek I, Feldstein MM (eds) Handbook of pressure-sensitive adhesives and products, fundamentals of pressure sensitivity. CRC Press, New York, pp 6-1-6-26 Dahlquist CA (1966) Tack. In The Ministry of Technology (ed) Adhesion fundamentals and practice. Gordon and Breach, New York, pp 143-151 Eaverarts AI, Clemens LI (2002) Pressure sensitive adhesives. In Chaudhury M, Pocius AV (eds) Surfaces, chemistry and applications adhesion science and engineering. Elsevier Science B.V, The Netherlands, pp 465-534... 

An interesting observation is that, while geckos and some insects have adopted hairy tissues for robust and reversible adhesion, some other insects and tree frogs seem to have achieved this via smooth tissues. The main similarity of both designs is that the structured pad surfaces or particular properties of the pad materials guarantee a maximum real contact area with diverse substrates. Dahlquisfs criterion, which is based on empirical observations of pressure-sensitive adhesives, establishes an upper limit for Young s modulus ( 100 kPa) of materials with tack... 

Adhesives. Acryhc emulsion and solution polymers form the basis of a variety of adhesive types. The principal use is in pressure-sensitive adhesives, where a film of a very low T (<—20 " C) acrylic polymer or copolymer is used on the adherent side of tapes, decals, and labels. Acrylics provide a good balance of tack and bond strength with exceptional color stabiUty and resistance to aging (201,202). AcryUcs also find use in numerous types of constmction adhesive formulations and as film-to-film laminating adhesives (qv). 

G-5—G-9 Aromatic Modified Aliphatic Petroleum Resins. Compatibihty with base polymers is an essential aspect of hydrocarbon resins in whatever appHcation they are used. As an example, piperylene—2-methyl-2-butene based resins are substantially inadequate in enhancing the tack of 1,3-butadiene—styrene based random and block copolymers in pressure sensitive adhesive appHcations. The copolymerization of a-methylstyrene with piperylenes effectively enhances the tack properties of styrene—butadiene copolymers and styrene—isoprene copolymers in adhesive appHcations (40,41). Introduction of aromaticity into hydrocarbon resins serves to increase the solubiHty parameter of resins, resulting in improved compatibiHty with base polymers. However, the nature of the aromatic monomer also serves as a handle for molecular weight and softening point control. 

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