Page 94 - Handbook of Surface Improvement and Modification

6.3 Application data 89

6.3 APPLICATION DATA

Reaction of a rosin (tall oil rosin, gum rosin, or wood rosin) with a polyol (glycerin, pen-
taerythritol, trimethylolpropane, trimethylolethane, diethylene glycol, dipentaerythritol, or
sorbitol) gives a rosin ester intermediate, which is then reacted with a dienophile (maleic
anhydride, fumaric acid, itaconic acid, citraconic anhydride, acrylic acid, methacrylic
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acid, or vinyl acetate) to produce an adducted rosin ester. The adducted rosin ester is fur-
ther esterified with a poly(ethylene glycol) having M < 700 to produce the water-dispers-
w
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ible adducted rosin ester. Esterification with the low-molecular-weight PEG imparts
good water dispersibility of the adducted rosin ester while maintaining compatibility with
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other tackifier components. Combination of the aqueous tackifier dispersions with poly-
mer emulsions, particularly acrylics, gives pressure-sensitive adhesives that deliver good
loop tack and peel properties compared with commercial alternatives, even when the coat
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weight is reduced by 20%. The best results are obtained when dienophile comprises 5%
or more itaconic acid and poly(ethylene glycol) has a molecular weight in the range of
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200-400.
A hot-melt adhesive composition for bookbinding contains a base polymer (a pro-
pylene-based elastomer, an amorphous poly-α-olefin (APAO) having a weight average
molecular weight in the range of 1,000 to 5,000, and optionally, an ethylene-based or pro-
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pylene-based plastomer), a wax (e.g., polypropylene wax having melting point of 150 C)
an oil (hydrotreated heavy naphthenic petroleum oil), a tackifier (Eastotac C-100W), and a
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stabilizer (antioxidant Irganox 1010). The hot-melt adhesive has a suitable viscosity for
processing. It is flexible for multiple flipping, sets fast to allow clean trimming, has a long
open time to accept cover, bonds well to various paper stocks, and has a wide operation
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temperature window for extreme high and low temperature application fields.
A hot-melt pressure-sensitive adhesive has environmentally-friendly composition,
good adhesion, thermal stability and coating performance, as well as an excellent hand-
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peeling property and alkali-peeling property. The hot-melt pressure-sensitive adhesive
developed for labeling comprises a polar functional group-modified conjugated diene-
based polymer (an amino group-modified styrene-ethylene/butylene-styrene block copo-
lymer or a maleic acid group-modified styrene-ethylene-butylene-styrene block copoly-
mer), an aliphatic polyester-based resin (a poly(lactic acid) or a poly(butylene succinate)
based ester), and a tackifier (a rosin-based tackifier resin having an acid value of 100 to
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300 mg KOH/g).
A hot-melt adhesive is based on a polymer mixture of an ethylene vinyl acetate poly-
mer with low vinyl acetate content (less than 20%) and a functionalized metallocene-cata-
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lyzed polyethylene copolymer. The adhesive contains Fischer-Troupe wax having
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melting point of 105°C and hydrocarbon resin having softening point of 100°C. The hot-
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melt adhesive has wide service temperature range for bonding cellulosic substrates. The
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adhesive is well suited for case, tray, carton and bag sealing applications.
Pressure-sensitive adhesives that minimize and/or resist plasticizer migration contain
a wax chosen from ethylene-acrylic acid copolymer, ethylene-vinyl acetate, or their mix-
tures, a natural rubber, a synthetic rubber (styrene butadiene rubber), a tackifier (C5
hydrogen resin having number average molecular weigh in the range of 500-1500), and a
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solvent (toluene). The adhesive was developed to be used with PVC substrates.