UV-curing acrylates

An increase of the light-intensity leads not only to a faster cure but also to a more complete polymerization 19. For instance, the amount of residual unsaturation of the UV-cured acrylate polymer was shown to drop from 15 to 5% when the light intensity was increased from to 3 to 100 mW cm-2. This trend can be explained by two factors (i), an increase of the sample temperature which provides more molecular mobility and (ii), a longer time lag between conversion and shrinkage... 

UV-cured acrylate coatings oxidize upon exposure to elevated temperatures (>139 C). The oxidation can be retarded by the addition to the coating of suitable antioxidants. 

Photostabilization processes have not received much attention in the last year other than a multitude of review and specialist industrial articles. These include stabilization of polypropylene fibres, new stabilizer developments, sorting of stabilizers for polyethylene, trends in UV absorbers, hindered piperidines (hindered amine stabilizers (HAS)) for polyacrylics and urethanes, new stabilizers for polyolefins, enhanced service life applications, stabilizer mas-terbatches for polyester, stabilizers for UV cured acrylic overcoats for PVC, ° stabilization of clearcoats and various commercial packages. ... 

UV-cross-linking acrylate resins. Generally, UV-curing acrylate resins contain [8] ... 

FIG U RE 11.14 Pyrogram of UV-cured acrylic ester resin at 400°C in the presence of TMAH along with its possible cross-linking stmctnre and formation pathway of products. Sample weight 0.1 mg reagent 4 pi of 25 wt% TMAH solution in water separation column metal capillary (30 m x 0.25 mm i.d.) coated with 0.25 pm of 5% diphenyl-95% dimethylpolysiloxane (Frontier Lab, Ultra ALLOY +5) column temp 30 (5 min)-230°C at 5°C/min. 

The use of a fibre-coupled confocal Raman microscope and an infrared microscope for both point mapping and global imaging in the study of spatial variations in polymer chemistry and morphology is illustrated by studies of the curing of the UV-cured acrylate coatings, crystallinity in drawn polyethylene terephthalate (PET) film, molecular orientation in PET bottles, and the analysis of a PES/PEES copolymer blended with epoxy resin and cured at elevated temperature. 8 refs. 

More commonly, acrylic polymers have been utilized as the sole or major components of radiation-curable adhesive systems. These acrylics have included a homopolymer and many examples of copolymers. One UV-cured acrylic ester copolymer system cited was claimed to have 180° peel strength of 4.8 to 5.5 pounds/inch. Radiation-curable systems based on copolymers of vinyl acetate and 2-ethylhexyl acrylate have been reported more frequently than other compositions and sometimes have been applied by hot melt techniques. These pressure-sensitive adhesives have displayed 180° peel strengths ranging from about 1.5 to 3 pounds/inch when cured by either UV or EB radiation. Not surprisingly, solutions of acrylic polymers in acrylic and vinyl monomers have also been used as radiation-curable pressure-sensitive adhesives. 

Matsubara et al., applied reactive pyrolysis gas chromatography in the presence of organic alkali to study the network structure of a UV.-cured acrylic ester prepared from polyethylene glycol diacrylate. An a-amino-aUcylphenone type photoinitiator was used. The network formation can be illustrated as follows... 

Mounting microchips on a printed circuit board UV curing acrylics... 

Silica-Filled UV-Cured Acrylates for Scratch-Resistant Coatings... 

Examples of unsaturated polyester and UV-curing acrylic coatings are given in Tables 16.1 and 16.2,... 

Eastman Chemical (UK) Ltd for the coil coating enamel formula in Table 13.3 and the polyester epoxy powder formulae in Table 14.4. Shell Chemicals for the can coating formula in Table 14.1 and the electrodeposition primer formula in Table 14.2. CIBA Polymers for the solventless epoxy formula in Table 14.3. Cargill Blagden for the one-pack polyurethane formulae in Tables 15.1 and 15.2. UCB sa for the UV-curing acrylic formula in Table 16.2. 

Litvinov, V. M. Dias, A. A., Analysis of Network Structure of UV-Cured Acrylates by NMR Relaxation, C NMR Spectroscopy, and Dynamic Mechanical Experiments. Macromolecules 2001, 34,4051-4060. 

Maurice PDL, Rycroft RJG (1986) Allergic contact dermatitis from UV curing acrylate in the manufacture of optical fibres. Contact Dermatitis 15 92-93... 

Fig. 36. DMA data at 1 Hz for a UV-cured acrylate pol3maer which is representative of a highly cross-linked system (79). The highly cross-linked acrylate represented has a very...

Figure 3 DMA recording of the storage modulus ( ) loss modulus ( ") and tan S for a UV-cured acrylate elastomer.

The major advantages of these UV-curable hybrid systems lie in their superior combination of properties which can be tailor-made for a given application by adjusting the proportions of the two components. The IPN formed will exhibit the main features of the two polymer networks, for instance the toughness and scratch resistance of UV-cured acrylate polymers and the elastomeric character of the cross-linked polyurethane-vinyl ether, with the expected benefit regarding adhesion and impact resistance. 

UV-cured acrylate functionahsed silicones have been successfully used as release coatings [125,129,134]. They consist of either acrylate end-capped linear polydimethylsiloxanes or of sdicone chains containing pendent acrylate groups. 

Sterilization. All devices implanted in the body or that come into contact with body fluids or blood must be sterilized and be resistant to the sterilization conditions. Adhesive-bonded parts are notused in direct contact with the body fluids. They are generally part of an electronic module that is hermetically sealed or otherwise encapsulated or shielded. However, the sterilization conditions for the module must not degrade the internal adhesive-attached components. Some adhesives such as cyanoacrylates and UV-cured acrylics degrade at the elevated temperatures and high humidity... 

The performance of different kinds of solder masks (UV-cured acrylated, thermally cured epoxies and alkyd/amine systems and dry film solder masks) under humid conditions at elevated temperatures is described by Fox All systems suffer from serious reduction of insulation resistance. The soldering process partially restores the insulation resistance. 

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