Adhesives for envelopes

Starch pyrodextrins and British gums have the abiUty, in aqueous dispersion, to form films capable of bonding like or unlike materials. Thus, they have uses as adhesives for envelopes, postage stamps, and other products. These dextrins are used in glass-fiber siting to protect the extmded fiber from abrasion, and as binders for metal core castings, water color paints, briquettes, and many other composite materials (qv). 

Envelope front seal adhesives are made from solutions of dextrins in water. They require high solid contents, usually 60 to 70%. Which of the two dextrin types (white or yellow) would be more suitable as adhesives for envelope seals ... 

Natural mbber latex is also used in adhesives for tape, packaging, envelopes, and in the footwear industry. It is used in the carpet industry as a binder for backing compounds, but this is another area in which synthetic SBR latex has competed effectively. There are a number of relatively small and specialized appHcations for natural mbber latex including mbberized coir or hair and cast products such as toys. Latex sheeting which is used in dental dams and for numerous other purposes can be made by dipping or casting onto a continuous belt. 

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. 

For example, poly(vinyl alcohol) (PVOH) finds application as an effective adhesive for paper products such as the old-fashioned postage stamps or envelopes. Licking the stamp or envelope flap causes the adhesive to become sticky because water plasticizes the PVOH and lowers the Tg below room temperature. On pressing the stamp to a piece of paper, the polymer chains can entangle and hydrogen bond with the cellulose in the paper. As the water... 

The adhesive for the seams on envelope backs must also be at a high solids to prevent strike through, allow fast production speeds, and provide lay-flat. Dextrins or pregelled starches may be used, but are usually heavily plasticized with the lower cost humectant-type plasticizers since blocking is not a factor on... 

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. 

Animal glues are used widely in a variety of ways with paper. For example, they have been the dominant adhesive for rewettable gummed paper tapes, labels, and envelope seals [69]. They are an important coadditive with synthetic wet-strength resins and rosin sizes for coated paper products [70]. They have been a primary binder for the grit that forms sandpaper [71]. 

Dextrins have many applications, with adhesives being their primary market (11,96). Dextrins are used as adhesives for case and carton sealing. For this application, borax is often added to the dextrin to add stability and increase viscosity. Dextrins are added to adhesives used in the laminating of products such as paperboard and shipping containers. The paper industry adds dextrins in adhesives for tube winding and bag adhesives. Library pastes, bottle label adhesives, envelop adhesives, gummed tape, and wall covering adhesives all benefit fiom dextrin addition. 

Dextrin compounds have strong adhesive properties and are used as pastes, particularly for envelopes, gununed paper, and postage stamps. Dextrin adhesives can bond to many different substrates. Paper and paperboard are the most common substrates. Laminating adhesives are usually made from highly soluble white dextrins and contain fillers such as clay. 

Solutions of Natural and Synthetic Polymers in Water. Aqueous Stank- and Dextrin-Based Adhesives. The starch- and dextrin-based adhesives reached their zenith between 1920 and 1935. Since then, they have been increasingly superseded by synthetic resin-based adhesives, and they are now important only in certain applications. However, they are still used in considerable quantities for applications such as labeling adhesives, paper-sack adhesives, and envelope gums. 

It was found, however, that an envelope of aluminum-laminated polymer film could not sufficiently stop moisture infiltration. A significant amount of moisture penetrated through adhesive for a margin of the envelope rather than through the aluminum-laminated film (Figure 8). To make this adhesive... 

One path for HIV infection may involve damaged (or healthy) vaginal epithelia [41,42] through cell surface adhesion [40]. Recently it has been reported that the major HIV envelope protein is held intact through hydrophobic residues [43]. For these and other reasons, we sought to combine hydrophobe substituted cationic polymers, particularly DCEs with active anionic polymers, with or without N9 present. 

Dextrins are produced by dry heating (roasting) starch in the presence of an acid catalyst. They are produced in a range of viscosity and color specifications. Dextrins are primarily used as adhesives in paper conversion, such as laminating and envelope production. A low-viscosity dextrin is used in Europe as a total chlorine free (TCF) coating binder for application on TCF paper. 

PVP is short for the polymer poly (vinyl pyrrolidone).1021 When PVP is left in the open air it absorbs around 15% of its weight as water from the air, such is its ability to cling to water molecules. It is also used in various personal care products like shampoos, toothpastes, and is the adhesive which has replace animal-based glues on envelopes and postage stamps. 

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