Self-adhesive tape adhesion

The use of coatings applied in the form of tape is also increasing. Polyethylene and polyvinyl chloride films, either self adhesive or else supporting films of butyl adhesive, petrolatum or butyl mastic are in use as materials applied cold at ambient temperatures. Woven glass fibre or nylon bandage is also used to support films of filled asphalt or coal tar and these are softened by propane gas torches and applied to the steel surface hot, cooling to form a thick conforming adherent layer. 

Spiral corrosion due to inadequate overlap has been detected with self-adhesive tapes, and a 25 mm (or preferably half-tape-width) overlap is to be advocated. Within normal limits, the thicker the adhesive the better. 

The self-adhesive tape coatings are thin and the adhesive itself does not necessarily come into contact with the valleys in the cleaned metal surface. Under these circumstances, the transmission of water vapour through the film to the metal may be possible. Moisture-transmission characteristics and other properties of p.v.c. and polyethylene tapes, as given by major manufacturers, are provided in Table 14.6. 

Table 14.6 is only indicative of general properties, and the latest developments of specific manufacturers of self-adhesive tapes may show advances on these. 

Weld joints may be coated in the field with FBE powder, utilising a portable blast cleaning/induction heating and powder application system. Alternatively joints may be provided with self-adhesive laminate tapes or heat-shrink crosslinked polyethylene sleeves. 

Repairs to the coating are made with either hot-melt polyethylene sticks or polyethylene sheet patches with mastic profiling compounds for small damaged areas. Large repair areas are best treated as for field weld joint coating, where either heat-shrink crosslinked polyethylene sleeves or cold-applied self-adhesive laminate tapes are employed. 

In addition to the petrolatum tapes and those based on a laminate of p.e. or p.v.c. with an elastomeric sealant or pressure-sensitive adhesive layer, recent developments have centred around self-adhesive bituminous laminates. These tapes are commonly constructed with a p.v.c. backing, whose thickness ranges from 0 08 to 0 75 mm and a bituminous adhesive compound layer to provide a total tape thickness of up to 2 mm. In order to maintain conformability without compromising impact values, tapes may also be manufactured with a fabric reinforcement within the bituminous layer. 

The monitoring of temperatures for electronic control systems is now mainly by thermocouples, secured onto the outside of the pipe with self-adhesive tape and the pipe then insulated over. 

Examples are given of the use of extruded PE foam sections in conjunction with other polymeric materials in the production of triangular, semicircular, rectangular and trapezoidal profiles, e.g. beam-like structures in which the rigid support may be of GRP. The foam can be bonded with thermally-fusible adhesives or two-sided self adhesive tape affixed to the foam prior to fabricating. A standard range of the foam prodncts is available, but other types can be tailor-made. 

The gel cassette is assembled according to manufacturer s instructions. Make sure that the glass plates are clean. If necessary, clean the plates with a common washing liquid, rinse thoroughly with water, and dry. Use plain spacers. Sealing of the cassette with self-adhesive tape, molten 1% agarose, or a small amount of polymerization mixture should be done only in exceptional cases. 

Hoinkins et al., (1967) glued the ion exchange particles to a cylinder that rotated in the solution and could be easily removed and reimmersed. Bunzl (1974b) attached peat particles to a polyvinylchloride (PVC) cylinder with self-adhesive tape. The cylinder, which had a small propeller at its lower end, was rotated at 470 rpm in an H solution to saturate the peat. Then the cylinder was dipped in Pb(N03)2 and removed at certain times. Interruption tests showed that FD was rate-limiting for Pb-H exchange on peat. 

Because of their conductivity, reflecting effect, and light barrier properties, metallized films are increasingly used as functional coatings in technical applications. Examples include battery cell cases, prepaid telephone cards, self-adhesive labels, insulation foil in the building industry, decorative foil for design elements, security features for bank notes, and tear tapes, etc. 

Attenuated Total Reflectance This method can be used to identify solid drugs but is only of use where relatively large amounts of compounds are available. The finely-ground sample is spread as a thin layer onto the sticky side of a piece of self-adhesive tape, and the tape is placed against the reflecting surface of the instrument with the sample side in contact. Sufficient sample is required to cover the surface of the tape completely, otherwise the spectrum of the tape will be recorded in addition to that of the sample. The technique is of use when the acid and salt forms need to be differentiated. 

Take a length of natch and with pieces of Crepe self adhesive tape l z l/4" stick the primed ends to the match about 1" apart. Hang up and light one end of the natch standing wall clear. 

Waste paper stock destined for recycling is normally segregated into grades according to whether the original pulp was produced by chemical or mechanical methods. The separate stocks are then repulped (dispersed) in a hot dilute solution of sodium hydroxide, sodium phosphate, or sodium silicate in water, and cleaned via a series of raggers, cyclones, and screens. Self adhesive labels and tapes pose a perennial problem in recycle pulps that a recently developed test method may help to solve [70]. Standard printer s inks... 

The exposed area of woodbased panels and other materials were 1.0 m. Thus the loading factor in the chamber is 1.0 m /m. The air change rate was 1.0 airchange per hour. Since the emission from the edges of the board often are higher, the edges are consequently sealed with self-adhesive aluminium tape. For preconditioned test pieces the steady state concentration will be reached within a week. 

Taping (plain and reinforced)—includes self-adhesive, water activated, heat activated ... 

Certain surfaces require some form of pretreatment prior to printing. Foil usually requires primer wash, and polyethylenes and polypropylenes need to have the surface oxidised. The corona process is almost invariably used for films and flame treatment for bottles. Whether a surface has received treatment or not can be detected by immersing it in water and observing whether or not the water runs off. An oxidised surface has a lower wetting angle. If the surface is not printed soon after treatment another treatment may be necessary. Inks will not key onto non-oxidised PE and PP and will be removed when a self-adhesive tape test is employed. 

Print adhesion on plastics (and foil) is normally checked using a self-adhesive tape peel test. A few inches of a suitable standard tape is firmly pressed onto the print area then pulled off, slowly at first, then more rapidly. An assessment of print adhesion can be made from the quantity (ideally none) removed. Adhesion can vary according to the type and colour of the ink, the degree of pretreatment, the surface involved and the printing process, etc. In order to test print under likely use conditions, product immersion tests may be necessary 60°C (140°F) is a frequently used condition, for 3 to 6 h. If product-pack may be used with soapy hands, a solution of soap can be employed. A print adhesion test, as above, can then be carried out, on the washed material, after it has been cooled to room temperature. 

Fig. 15. Assembly of a gel cassette for casting IPGs, (a) Glass base plate (3 mm thick) (b) Gel Bond PAG foil (c) U-gasket (in general silicone or rubber, often glued to the glass cover plate usually 0.5 mm thick) (d) Template 3 mm thick glass plate with pieces of self-adhesive Dymo tape (250 p.m thick) for moulding of gel slots (e) paper clips as temporary, additional spacers. (From Gorg et al., 1978. Reproduced with permission of the publisher.)...

Personal hygiene products such as disposable diapers make use of self-adhesive strips, covered with a release tape that is removed at the point of use. Again unmodified acrylic dispersions as well as hot melts dominate this application. The same considerations apply here as in first-aid dressings, and in particular the adhesive must not cause skin irritation. 

Not only fibres can be produced with such technologies. Once the cellulose or its derivative is dissolved, this dope can be shaped into other bodies like hollow fibres for membrane applications (artificial kidney), membrane films, packaging films (e.g. Cellophane), self-adhesive tapes (Sellotape), or sponges. 

The easiest way to patch test a patient s own products is using tapes and medical self-adhesive dressings. Simply cut a small piece and stick it to the skin for 24-48 h. For further information, refer to the other chapters in this book that deal with acrylates and epoxy resins. 

Single- and double-sided self-adhesive tapes come in many forms and sizes, using a variety of backing materials such as - cellulose, polyester, foamed polyurethane and PVC. The adhesive is usually based on a tacky, semi-solid acrylic polymer which may be used with a release strip. Some special tapes are heat activated. 

Self-adhesive oxygen absorbers are available in various forms such as FreshMax (Multiform Desiccants, Buffalo, USA), Smartcan (Aquanautics Corporation, Alameda, California, USA) and including sachets with adhesive tape. There is some resistance to such an approach with pow-... 

This desalptiou of a spreading drop apphes only when the surface is absolutely smooth. However, most surfaces contain pores and crevices into which the liquid must flow if complete wetting is to be achieved (Figures 4.3 and 4.4). Air ttapped in a pore will oppose the penetration of the liquid. If the air has time to diffuse out of the hole before the adhesive sets, the penetration will be deeper. This is one cause for the increasing adhesion of self-adhesive tapes with time, since the adhesives used remain Uquid. A consolidant or adhesive used in conservation should be given time to penetrate before it hardens. A low-viscosity liquid is obviously more likely to flow readily into the pores. 

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