Oligomers urethane acrylate

Oligomer urethane acrylate (LR 8739) and photoinitiator Irgacure 184 were obtained from IAEA. Reaction diluents 2-methoxy ethyl acrylate (MEA, Tg = -110°C), 2-ethylhexyl acrylate (EHA, Tg = -50°C), 2-hydroxy ethyl methacrylate (HEMA, Tg = 55°C), N-vinyl pyrrolidone (NVP, Tg = 175°C), tripropylene glycol diacrylate (TPGDA, Tg = 90°C), and trimethylol propane triacrylate (TMPTA, Tg 250°C) were used as procured from E, Merck without any further purification. 

There are two approaches to forming urethane-acrylic hybrids. First, an acrylate terminated urethane oligomer can be used [147]. Alternatively, polyisocyanate and benzoyl peroxide can be combined in one side of the adhesive, and methacrylate monomers and urethane curatives (especially polyols) in the other [148]. 

Reactive oligomers such as epoxy resins, isocyanate-terminated compounds, and urethane-acrylates are extremely useful in the adhesive, coating, reaction injection molding (RIM), sealant and... 

Improved heat-resistant UV compositions for optical fiber applications These compositions are nonurethane UV cure compositions that have neither carbamate moieties nor long-chain poly(alkylene oxide) soft segments and exhibit inherently better thermal stability measured by thermogravimetric analysis (TGA) than typical coatings for optical fibers based on urethane acrylate oligomers. 

An acrylic oligomer is a higher molecular weight functional acry-lated molecule which may be, for example, polyesters of acrylic acid and methacrylic acid. Other examples of acrylic oligomers are the classes of urethane acrylates and urethane methacrylates. Urethane acrylates are manufactured from aliphatic or aromatic or cycloaliphatic diisocyanates or polyisocyanates and hydroxyl-containing acrylic acid esters. 

In an earlier investigation by Yang [1] triblock urethane acrylate oligomers terminated with acrylic acid were prepared and used in curable pressure sensitive adhesive compositions. 

Figure 3.84. Voxel obtained by irradiation of a mixed urethane acrylate oligomer and a urethane acrylate monomer in the presence of a mixture of benzoyl cyclohexanol and morpholino phenyl amino ketones at 780 nm using a 150-fs pulsed Ti sapphire mode-locked laser operating at 76 MHz, where light was focused by a 1.4 numerical aperture objective lens (a) scanning electronic microscopic images of the voxel and (b) longitudinal and lateral voxel size as function of the exposure time. (From Ref. [580] with permission of the American Institute of Physics.)...

The uncured conformal coatings are clear, transparent liquids with viscosities of 700 to 1400 cp at 25°C. A typical composition which has a viscosity of 820 cp at 25°C consists of 43 wt % of a high viscosity urethane acrylate oligomer, 49 wt % of a low viscosity monoacrylate diluent, 5 wt % of a polyfunctional thiol, 2 wt % of benzopinacol and 1 wt % of alpha, alpha-dimethoxy-alpha-phenylacetophenone. A trace amount of a fluorescent dye may be added, if desired, to facilitate inspection of the finished coating. 

Acrylated oligomers can be divided into three main classes polyester acrylates, epoxy acrylates, and urethane acrylates. Urethane acrylates are an especially important commercial class of oligomers. Applications Include binders for magnetic media, vehicles for inks, and coatings for vinyl floor tiles, optical fibers, and paper. Each application has certain performance requirements that must be met by the urethane oligomer. This paper will discuss the effect of urethane acrylate composition on end properties. 

The use of a symmetrical diisocyanate (HMDl), in which the two NCO groups possess the same reactivity, will produce an oligomer with a higher viscosity than one that contains an unsymmetrical diisocyanate (TDI or IPDI). This is due to the presence of more extended urethane acrylate (Figure 2) in HMDI based oligomers. ... 

The composition of urethane acrylates can be varied In order to achieve certain end properties required by the Intended application. The structure-property relationships discussed In this paper can provide guidance In the intelligent design of this class of radiation cure oligomer. 

The typical structure of urethane acrylate oligomers is shown in Figure 11.3. The chemistry of urethane acrylate is very versatile. Essentially, the chemistry and the final properties of urethane acrylate coatings are governed by the chemical structures of isocyanate and polyol and functionality. 

Figure 11.3. By choosing a suitable monomer, the degree of branching, and molecular weight of the polyester, one can customize the properties of the resulted polyester acrylate oligomers, such as flexibility (Tg), viscosity, functionality, reactivity, and other end properties of the final coatings. The performance properties of polyester acrylates lie between those of epoxy acrylates and urethane acrylates (Table 11.2).

Urethane acrylate oligomer, rheology modifier resin ... 

Polyols used for this purpose include trimethylol propane and propylene glycol. Systems containing urethane-acrylate oligomers bearing doubly-functionalized isocyanate groups are commercially available [24]. The chemical structure... 

Chart 11.4 Chemical structures of oligomers bearing acrylate and isocyanate groups isocyanato-allophane acrylate (left) and isocyanato-urethane acrylate (right) [24]. 

Chem. Descrip. Aiiphatic urethane acrylate Uses Urethane-acrylic for UV/EB-cured flexible varnishes, adhesives, inks plasticizer for other radiation-curable oligomers Features Difunctional rec. for low vise. wh. inks or transparent coatings where nonyellowing is essential produces films with good reactivity, adhesion, exc. flexibility... 

Chem. Descrip. Brominated urethane acrylate oligomer congt. isobomyl acrylate (25%)... 

Chem. Descrip. Aliphatic urethane acrylate oligomer Uses Urethane-ac ic, plastidzer for UV and EB-curing printing inks, plastic coatings... 

Chem. Descrip. Aliphatic polyether-based urethane acrylate oligomer blended with hexanediol diacrylate... 

Chem. Descrip. Aliphatic urethane diacrylate oligomer with acrylate monomer (30%) diluent... 

Chem. Descrip. Aliphatic urethane acrylate resin/SR 454 (ethoxylated trimethylolpropane triacrylate) blend, < 400 ppm MEHQ inhibitor Uses Urethane-acrylic for adhesives, coatings (metal, paper, PVC floor, wood), electronics, inks, photopolymers Features High performance difunctional oligomer hard, nonyellowing Properties APHA 100 clear liq. sp.gr. 1.104 vise. 2300 cps tens. str. 9000 psi tens, elong. 31% 99% reactive esters 75% oligomer, 25% EOTMPTA... 

Chem. Descrip. Aliphatic polyester-based urethane diacrylate oligomer Uses Urethane-acrylic for coatings, flexible pkg., screen inks Features Difunctional low vise. exc. conformal props. good weatherability, chem. resist., flexibility, adhesion, heat resist., abrasion resist., impact str., water resist. low shrinkage Properties APHA 55 clear liq. dens. 9.213 Ib/gal vise. 660 cps (60 C) ref. index 1.4882 tens. str. 945 psi 1% mod. 3557 psi elong. 53% CN996 [Sartomer]... 

Chem. Descrip. Aromatic urethane aciylate oligomer Uses Urethane-acrylic tor UV-curable metal coatings, plastic coatings, inks... 

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