Adhesives for laminating

Formed commercially by the polymerization of S, NajCOj and PhX in a sealed container at 275--370 C, substituted derivatives are known but not fully evaluated. Used as high-temperature adhesives, for laminates and in coatings. 

Standard specification for phenolic and aminoplastic adhesives for laminating and fingerjointing of timber, and for furniture and joinery. SABS 1349-1981, South African Bureau of Standards, 1981. 

If one amino group in o-phenylenediamine is converted to an amide group by formic acid, the intermediate benzimidazole is formed. This reaction, conducted with a wide range of reactants, produces resins (polybenzimidazoles) used as high-temperature adhesives for laminates in the aerospace industry. Heat insulation is made by including tiny bubbles of silica and all... 

Lignins from waste hquors are also used as extenders for phenoplasts and in adhesives for laminated paper and board, hnoleum pastes, animal feedstuff pellets, etc. 

Large quantities of starch are consumed as a component of adhesives for paper and paperboard, especially in the production of corrugated board. Dextrins, derived from com or potato starch, are used as adhesives for laminated products and as gums for envelope construction and sealing. 

Adhesives for Laminating. Solid fiberboard for boxes and shipping containers is tough and durable due to a combination of two or more plies of paperboard bonded with a solid fiber laminating adhesive ( ). Warping can be a problem,... 

Substances used in the manufacture of adhesives for laminated materials are not specifically listed in the Plastics Directive 2002/72/EC. Within the EU,... 

Durability to Washing Excellent Durability to Drycleaning Good Forms stiff films. Recommended as an adhesive for laminating when good drycleaning resistance is required. 

PVAc-dispersion with plasticizer, adhesive for laminating textile/textile and textile/paper, filling agent for textile finishing. 

Polyurethanes are produced by the chemical action of di-isocyanate and polyol. The properties can be varied by the type of isocyanate used and the proportion of the two monomers. There are four main groups of classification for the thermoplastic groups of polyurethane, i.e. rigid foam, flexible foam, non-cellular and cellular polymers. Two main isocyanates used are toluene di-isocyanate (TDI) and diphenylmethane diisocyanate (MDI). Polyurethanes have limited application in the pharmaceutical or medical industries. Polyurethane is used as an adhesive for laminations (thermosetting material). Like thermosetting polyurethane, thermoplastic polyurethanes can be found as esters and ethers. 

Similarly, a polyurethane containing polyester segments is an effective adhesive for lamination of PET film to wood. The polyester segment of polyurethane is compatible with the polyester film surface while the urethane linkages provide hydrogen bonding interaction between adhesive and substrate (Diagram 12). 

Products and Uses A nutritious milk protein containing all the essential amino acids. Used in a wide variety of products including cheese, interior paints, adhesives for laminates (plywood), feeds, and dietetic preparations. Acts as a thickener, whitening agent, binder, coating, glue, and sizing. 

Acrylics and urethanes are used as adhesives for laminations, also. These adhesives are known as two-part systems, and they require time to cure after the lamination is formed before they reach their final bond strengths. The chemical cross-linking reactions take place during the curing process. 

Casein adhesives are based on milk protein. They are used for labeling reflllable beer bottles because they resist cold water immersion but are readily removed in an alkaline wash when the bottles are returned. Another use is as an ingredient in adhesives for laminating aluminum foil to paper. 

Natural rubber adhesive, or latex, is used in self-seal applications, where it makes use of its unique ability to bond only to itself with pressure. Applications include selfseal envelopes, press-to-seal cases, and cold-seal candy wraps. Natural rubber latex is also used in adhesives for lamination of polyethylene film to paper, such as in multiwall hags. 

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. 

Another technique that has been described recently is the use of an adhesive for lamination. In this process, the lamination is accomplished by gluing at room temperature and at very low pressures using an adhesive tape. The authors report that homogeneous monolithic sintered structures resulted using this technique. 

Resins based on para-substituted phenols can be either one-step or two-step, but they cannot cure to a thermoset state. In the manufacture of phenolic resins, smaller quantities of acetaldehyde and furfuraldehyde are used in addition to formaldehyde. Furthermore, resorcinol, bisphenol A, and p-alkylphenols are employed, in addition to phenol, when special properties are desired. Formaldehyde concentrations of 37-50 weight % in aqueous solutions are most commonly employed. The catalysts most frequently used are acids such as oxalic, hydrochloric, sulfuric, p-toluenesul-fonic, and phosphoric and bases such as sodium, calcium, and barium hydroxide. In the weakly acidic range metal carboxylates are employed. Thermoset phenolic resins are employed as structural adhesives for laminating and bonding applications. Para-alkyl-substituted resins are employed as tackifiers in contact adhesives, pressure-sensitive adhesives, and hot-melt adhesives. 

Figure 4 UV curing of an adhesive for laminates (source DELO Germany).

Adhesives for Laminated Films. Laminated films are currently produced by two techniques lamination and extrusion. In lamination, the low-viscosity adhesive solution is applied by rolls to one of the films in a thickness of a few micrometers and dried. The two films are then combined in the laminator. The adhesives used are either two-component or one-component, moisture-cross-linking polyurethane adhesives, depending on requirements (type of film, sterilization resistance, sealing seam strength, etc.). Besides the traditional solvent-based systems developments have been made in the direction of solvent-free systems (high-solids products) and of polyurethane emulsion-based systems. 

RF resin is also used to make fast-curing adhesives for laminated timber and beams as well as adhesive applications in building construction. 

Table 2. Adhesive for Lamination of Aiuminum Foii to Kraft Paper.

Chapter 8 Adhesives for packaging and paper, bookbinding, by P. Cognard Chapter 9 Polyurethane adhesives for laminating and packaging, by J. F. Lecam, Bostik-Findley... 

Polyurethane chemistry and adhesives and sealants is such a large and important topic that several chapters will he spent covering this subject A general chapter in Volume 1 (written by a team of scientists from Loughborough University in the UK), PU sealants in Volume 3, PU flexible adhesives and sealants by Sika in Volume 2 and again in Volume 5 probably, and PU adhesives for laminating and packaging in Volume 4 by Bostik-Findley. 

A detailed study of PU adhesives for flexible packaging is provided in Volume 4 by the chapter PU adhesives for laminating by J-F LECAM. 

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