Acrylates prepolymers

Reactive prepolymers used as binders are produced by acrylation of oligomers, such as epoxy resins, urethanes, polyesters, silicones, oligo-buta-diene, melamine derivatives, cellulose, and starches. Prepolymers are the principal ingredients of coating formulations and largely determine the basic properties of the coating. Examples of industrially important acrylated prepolymers are in Table 5.9. 

Examples of Acrylate Prepolymers Used for Radiation Technology... 

Tensile strength of radiation-cured purified natural rubber Tensile strength of radiation-cured purified natural rubber Examples of industrially important acrylated prepolymers The arrangement for direct roll coating Different types of cells on the surface of a gravure roll Reverse roll coating... 

Several studies have concentrated on the photocrosslinking of epoxy-based resins. Using differential scanning calorimetry the photocuring of epoxy and acrylic prepolymers has been disturbed by the... 

Figure 8. Schematic structure of silicone and thermoset acrylic prepolymers (4)...

Baxendale, Evans, and Parks—Styrene and methyl acrylate prepolymers linked with diisocyanate to give (A-B)n block polimiers. 

In 19A6, Baxendale, Evans, and Parks reported (25) on a stepwise formation of an (A-B)jj block polymer in which low molecular weight polystyrene and methyl acrylate prepolymers were linked with diisocyanate to form a high molecular weight, multiblock polymer. 

Typical resin formulations contained 2 to 5 % of photoinitiator and equal parts of the acrylic prepolymer and of the diluent. The resin was applied as a uniform layer of controlled thickness, between 12 and 36 un, on a KBr disk with a calibrated wirewound applicator. 

Acrylated prepolymers usually have high viscosities and require a diluent. This can be an acrylate monomer or a low-toxicity monomer that itself takes part in the curing reaction. The use of such reactive diluents results in changes to the viscosity, flexibility, and the speed of cure of the formulation. 

For the synthesis of urethane-acrylate prepolymer, hexamethylene diisocyanate (HDI, 0.178 moles,) was placed in a reaction vessel, then 2-hydroxyethyl-acrylate (HEA, 0.178 moles) was added. The reaction temperature was kept at 45°C for 30 min., to avoid thermal polymerization through the vinyl groups, then a stoichiometric quantity of dry polypropylene glycol (PPG) (MW 725, hydroxyl number 147 mg of KOH/g (67.4 ml.)) was added along with dibutyl-tin-dilaurate as a catalyst... 

Chem. Descrip. Acrylic prepolymer emulsion Uses Acrylic for interior flat latex paints, primer sealers, exterior masonry, exterior wood stains, caulks, sealants, and mastics Features Prevents paint blistering/peeling soon after applic./before the paint film is leached of its water exiraclables provides alkali resist., pig-... 

A curing agent, such as an organic peroxide, may be added to the acrylic prepolymer mixture to enhance the crosslinking of the prepol miers and thus the subsequent solidification of the resulting polymer to form a matrix. 

Acrylic prepolymers containing 5-40% aminoalkyl(meth) acrylate units and having 1000-50,000 m.wt. are treated with functional group containing unsaturated compounds to give photocurcible PSA s. ... 

Jap. Kokai Tokkyo Koho JP 82 051-780 1982 Hitachi Radiation curable adhesive tape production from (meth)acrylate prepolymer. 

Gummeson reported that the triazine ring has six reaetive sites that ean be utilized to prepare materials with a range of unsaturated funetionality for light euring. This allows formation of a number of acrylated prepolymers. An aerylated melamine resin was illustrated as follows... 

Gummeson s data shows, however, that these materials do not cure as rapidly as do the epoxy acrylate prepolymers.Their shrinkage, however, is lower than that of the epoxy acrylates. Also, he reported that these prepolymers yield films that possess better adhesion to the substrate and better abrasion resistance than films formed with epoxy acrylates. 

Trimethylolpropane triacrylate Benzoylhexanol Urethane acrylate prepolymer Product 65 (shop primer for concrete floors) Methyl methacrylate 91... 

Bjorkner B (1981) Sensitization capacity of acrylated prepolymers in ultraviolet curing inks tested in the guinea pig. Acta Derm Venereol 61 7... 

Determination of Hydroxy Groups in DinitropropyI Acrylate Prepolymer... 

Titier, C., Pascault, J. P, Taha, M., and Rosenberg, B. J., Epoxy-amine multimeth-acrylic prepolymers, kinetic and structural studies, J. Polym. Sci., Part A, Polym. Chan., 33, 175, 1995. 

Kim et al examined the strong infi ared band at 3450cm of tetrahydrofiiran associated hydroxy groups in dinitropropyl acrylate prepolym in order to det mine hydroxy groups. 

Scheme 8.21 Synthesis of the citric acid based unsaturated prepolymers from citric acid 1,8-octanediol and glycerol l,3 diglycerolate diacrylate or bis(hy-droxypropylfumarate) (A) acrylated prepolymers (B) fumarate-con-taining prepolymers.

These vinyl esters are di(meth)acrylic prepolymers obtained by the reaction of (meth)acrylic acid with diglycidic ether of bisphenol A (DGEBA) (precursor of epoxy resins) (see Section 16.6). The reaction can be catalyzed by amino or phosphonated bases... 

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