Specialty adhesives

In formulating adhesives, it is desirable to use materials with low cost. For specialty adhesives such as the acrylics, it is preferred to use commodity chemicals with a range of other uses. Minor components such as reactive rubbers, functional monomers and some additives are specially synthesized for acrylics, but these are expensive due to low volume. 

Kothari, V. M., Specialty Adhesives Can Be Compounded for Applications in Many Market Niches, Elastomerics, October 1989. 

Arofene . [Ashland] Phenolic resin for impregnating/specialty adhesives. 

The Adhesive The choice of the proper adhesive for one s label is quite obviously of major importance. The two t3rpes of adhesives generally used for pressure sensitive label construction are rubberbase and acrylic emulsion. In addition, most converters of label stock offer a variety of specialty adhesives to meet particularly demanding applications. Some of the terminology associated with pressure sensitive adhesives is as follows. 

A novel, latent curing system, which gives more than one year pot life at room temperature, has increased the use of epoxies for specialty adhesives and sealants, and for vinyl plastisols. The one-pack system provides fast cure when heated—for example 5 min at 100°C. 

DERMIL RESEARCH LTD. 24 Buckingham Square, Wickford Business Park, Wickford, Essex SSll 8YO UK, phone +44 (0)1268 732573, fax -1-44 (0)1268 732516. Intabond Specialty Adhesives for Laminating and Coating. 

STUDIO TAMBURINI Via P. Fomari 46, 20146 Milano Italy, 39 (2) 48704572. The European Market for Specialty Adhesives and Sealants. 

The emergence of the DH acrylic adhesives occurred concurrent with the introduction of the so-called HP or high performance acrylic adhesives. This type of system, as with the DH types, offered users the ability to bond through oily metals, but did not require the use of awkward oily primers. They also were based on formulations that contained specialty adhesion promoting components, often contained monomers that were less flammable than first generation products, and often were also considerably lower in odor. 

Chem. Descrip. Resin of dimeric adds derived trom rosin with lesser amounts of monomeric resin acids, and neutral material of rosin origin Uses Thermoplastic resin used in mtg. of protective coatings, spirit varnishes, epoxy ester resin vehicles, adhesives, and printing inks as a soldering flux tackitier tor NR, SBR, NBR, PS, PVC reinforcement for specialty adhesive prods. 

Uses Polyamide for thread bonding, specialty coatings, color cone, carrier resin, specialty adhesives, and polymer additives Features Chem. resist. lower melt temps. 

Chem. Desap. Pentaerythrityl rosinate, maleic-modifled CAS 8050-26-8 EINECS/ELINCS 232 79-9 Uses Resin in printing ink vehicles, soft oil-based paints and varnishes, specialty adhesives... 

Besides bulk adhesives, many new specialty adhesives have been developed to meet various socio-economical needs, e.g., time-saving, energy-saving, non-polluting, etc. As a result, we have seen several important transitions for the developments in adhesives chemistry ... 

As a whole, adhesive technologies have gradually transformed from art to science. Industry-wise, automation and robotics have started to replace old-fashioned operations. Both productivity and profits have been improved. As a result, as recession hit the bottom in late 1982, while many industries suffered from financial losses, the specialty adhesive industries made some impressive gains. 

The use of synthetic adhesives in the past twenty-five years (1) has grown/ particularly the use of eight classes of polymers polyvinyl acetate/ polyolefins/ styrenic block copolymerS/ acrylicS/ cyanoacrylates/ anaerobicS/ polyurethanes/ and epoxy resins. Some of these polymers are Still in high demand as specialty adhesives (2). During the last several yearS/ however / other polymers have been added to this list/ e.g. / polyamides/ polyimideS/ and polyesters. Today/ synthetic adhesives account for 75% of the adhesives produced and 85% of the sales/ while the market share of natural products has steadily declined. 

Adhesives are extremely important components of most fabricated products. They play a functional role which is nearly always invisible. Because of their enabling role, users and consumers notice an adhesive only when it fails. The nature of the adhesives function has placed pressure on the prices of adhesives. The economics of non-specialty adhesives have followed the path of other commodities. At the same time, performance requirements have escalated over time. A great deal of consolidation has been taking place among the manufacturers of adhesives (and sealants). 

Polyurethane materials exist in a variety of forms including flexible or rigid foams, chemical resistant coatings, specialty adhesives and sealants, and elastomers. Most polyurethanes are thermoset materials they cannot be melted and reshaped as thermoplastic materials. Once the reactions have ceased the thermoset polyurethanes are cured and cannot be heat shaped without degradation. The thermal stability results from the croslinking degree of polymer chains (the crosslink density) and from the nature and frequency of repeating units within the polymer chains. 

Carborane plastics are produced from the boron molecule (a boron hydride of composition B10FI14) by replacing the four terminal hydrogens with two carbon atoms. The monomer polymerizes at high heat and pressure to form rubbery solids, which will withstand temperatures above 315°C but the commercial plastics are usually copolymers with vinyls, sihcones, or other plastics. Carboranes have been used as specialty adhesives in the aerospace industry. 

Specialty adhesives such as EVA-copolymers, polyurethanes, etc., are formed by the melt-blown technology into webs for the assembly of components in diapers, automotive, furniture, carpets, bags and other industrial products. 

A wide variety of epoxy resins are commercially available monofunctional or polyfunctional, aliphatic, cyclic, or aromatic. Brominated epoxies may be useful where flammability is a concern. An oxirane functionality is all that is needed to make an epoxy resin, and structural adhesives are only one of over a dozen different uses for epoxy resins. Many epoxy resins on the market will not necessarily be suitable for adhesives, but their availability does expand the choices available for adhesive formulators. The specialty epoxy resins developed specifically for adhesive use sometimes will be more costly than the DGEBPA resins but may provide the basis for a specialty adhesive that can meet a unique need and therefore command a proportionally higher price. Examples of these are epoxy-fimctional dimer acids, urethanes, and various elastomers. 

UV-curable adhesives have established themselves as a significant part of the overall market for specialty adhesives because they offer a number of advantages over traditional adhesives, as illustrated in Fig. 13. One can expect this part to increase in the near future, as the ever more stringent regulations aiming to lower air pollution and energy consumption will progressively curtail the use of solvent-based adhesives. 

---