Photocurable monomers

For aqueous inks, the resins are water- or alkali-soluble or dispersible and the solvent is mosdy water containing sufficient alcohol (as much as 25%) to help solubilize the resin. To keep the alkah-soluble resin in solution, pH must be maintained at the correct level. Advances include the development of uv inks. These are high viscosity inks that require no drying but are photocurable by uv radiation. In these formulations, the solvent is replaced by monomers and photoinitiators that can be cross-linked by exposure to uv radiation. The advantage of this system is the complete elimination of volatile organic compounds (VOC) as components of the system and better halftone print quaUty. Aqueous and uv inks are becoming more popular as environmental pressure to reduce VOC increases. 

The cured polymer samples used for physical property testing were prepared by photocuring 12 mil thick sheets of degassed and photosensitized monomer mixtures, using a mold composed of glass plates lined with polyester film and separated by a double thickness of vinyl electrical tape. A GE sunlamp was used for Illumination, and Darocure 1173 (E. Merck) was used as the photoinitiator. Hydrocarbon monomers were used as received from the manufacturers. All the vinyl group-containing compounds were stored at -5°C until use. 

Alkenyloxystyrene monomers such as 4-allyloxystyrene are useful components of photocured cationically polymerizable compositions. Used alone or in combination with divinyl ethers they provide low viscosity formulations, which are excellent solvents for commercial onium salt photoinitiators. Photocuring rates are comparable to vinyl ether monomers and the initially photocured alkenyloxystyrene polymers may be further heat processed to yield crosslinked phenolic type resins having outstanding thermal resistance properties. The new materials have good adhesive properties and are potentially useful where a combination of ease of processability and high performance is required. 

Para-t-butylphenyl glycidyl ether BPGE had a similar viscosity and C/O ratio as those of NA and had the best properties of the photocurable epoxies that were surveyed, but this monomer dewetted from Si substrates immediately after spin coating and formed a puddle at the substrate center. Other monofunctional epoxies exhibited the same behavior. Mixtures of BPGE with multifunctional aromatic epoxies wetted Si substrates and could be used as planarizing layers. 

We chose to modify the anhydride monomers with photopolymerizable methacrylate functionalities. Methacrylate-based polymers have a long history in biomedical applications, ranging from photocured dental composites [20] to thermally cured bone cements [21]. Furthermore, photopolymerizations provide many advantages for material handling and processing, including spatial and temporal control of the polymerization and rapid rates at ambient temperatures. Liquid or putty-like monomer/initiator... 

Curing by light irradiation can be apphed to a variety of polymers. The acrylic family is a typical example of photosensitive monomers. A well-documented review has recently been dedicated to the curing of composites by ultraviolet radiation [45], Photocuring time is much shorter than for traditional thermal curing (minutes rather than hours), leading to a significant reduction in the cycle time. 

Recent concerns over the residual concentration of free thioxanthone photoinitiators and amine coinitiators in coatings and inks on food packaging have resulted in the evolution of macroinitiators <2002PLM4591, 2003JPH(159)103> or polymeric photoinitiators <1996MI379> wherein the thioxanthone unit and, in some instances, the amine coinitiator are covalently bound to a copolymer which is formulated with the ink or coating and then photocured in the normal way. Several copolymers, for example, 636, based upon the polymerization of acrylate esters derived from 4-hydroxythioxanthones with either acrylamide or 2-acryloxyethyltrimethylammonium iodide co-monomer have been explored as water-soluble photoinitiators <2005JPH(169)95>. 

Photocurable coatings are widely used for metal, plastics wood and paper. Photoinitiated free-radical polymerization, however, can only be applied to vinyl monomers. The studies of Crivello have broadened the scope of monomers. In addition, photoinitiated cationic polymerization is not sensitive toward oxygen (air). Photoinitiated free-radical polymerization sometimes requires working in inert atmosphere in order to avoid the inhibition through oxygen1). 

The preparation of other in vivo implants using photocurable coumarin end-groups and at least one lactone monomer selected from s-caprolactone, glycolide, or DL-lactide is described by the author [2]. 

Diacrylate monomers have been prepared that are photocurable in visible light and that have small polymerization shrinkage and high X-ray contrast properties. When polymerized with 0.01 to 0.04 pm glass powder, these dental composites were easily machined into artificial teeth. 

Polymerization of epoxy monomers, requiring probably the simultaneous participation of the phenolic hydroxy group, and the production of polyurethanes are the main applications of the abovementioned catalysts. In particular, their role in the trimerization of the i.scx yanate group " appears quite relevant and several investigations of the synthesis of epoxy resins-- " - and polyurethanes- arc reported. A different type of catalyst is constituted by acetophenone-derived p-aminoketones employed with photocurable resins. -- ... 

Sellinger and Laine [34] presented methacrylate/cube hybrids (XXIX) (Scheme 8) that can act as thermosets or photocurable monomers. 

The reaction of glycidyl acrylate with a-(2-carboxyethyl)benzoin methyl ether has allowed one to obtain [101] the corresponding acrylic monomer which, upon copolymerization with different amounts of MMA, butyl methacrylate and 2-(V, V-dimethylamino)ethyl methacrylate, gives rise to polymeric photoinitiators, containing side-chain benzoin methylether moieties, for photocurable coatings ... 

Vinyl ether and epoxy chemistry established more than 50 years ago finally found its way into radiation curing technology. These compounds have been demonstrated to be reactive monomers in curing processes photoinitiated by iodonium and sulfonium salts. In particular, vinyl ethers are known to be among the most reactive monomers in photocuring chemistry. 

In silicone chemistry, there has been recently a resurgent interest in the chemistry and technology of photocurable compositions derived from epoxy and vinyl ether silicones. Several types of silicones with vinyl and epoxy groups were designed [1, 2] which differ in functionality, spacer group and monomer content. The cured products have excellent physical properties and are of commercial interest in a number of areas. The crosslinking chemistry of such modifided silicones involves the well known cationic crosslinking/polymerization of vinyl ethers. The silicone unit acts basically as an internal solvent. The... 

Cho and Hong (2005) used photodifferential scanning calorimetry to investigate the photocuring kinetics of UV-initiated cationic photopolymerization of 1,4-cyclohexane dimethanol divinyl ether (CHVE) monomer with and without a photosensitizer, 2,4-diethylthioxanthone (DETX) in the presence of a diaryliodonium-salt photoinitiator. Two kinetic parameters, the rate constant (k) and the order of the initiation reaction (m), were determined for the CHVE system using an auto-catalytic kinetics model as shown in the following equation ... 

Photopolymer systems are photocurable resins incorporating reactive liquid monomers, photoinitiators, chemical modihers and hhers. Typically stereolithography utilizes UV radiation, so UV-curable systems are used. Free-radical-photopolymerizable acrylate systems were originally used however, newer cationic epoxy-resin and vinyl ether systems (based on iodinium- or sulfonium-salt cationic initiators) are now being utilized. 

S. Minegishi, et al., Novel photocurable monomers the synthesis of difunctional vinyl ethers with a phosphonate group and difunctional 1-propenyl ethers with a phosphonate group and their photoinitiated cationic polymerization. J. Polym. Sci. A Polym. Chem. 2005, 43(14), 3105-3115. 

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