UV-curable Adhesives Research Articles

Synthesis of Poly(methyl urethane) Acrylate Oligomer Using 2-Isocyanatoethyl Methacrylate for UV Curable Coating

The poly(methyl urethane) acrylate oligomer was obtained by the reaction of methyl acrylate oligomer and 2-isocyanatoethyl methacrylate. Synthesis of poly(methyl urethane) acrylate oligomer was done with 2-mercaptoethanol (2-MEOH), methyl acrylate, 2,2'-azobisisobutyronitrile (AIBN, initiator) and dibutyltin dilaurate as a catalyst. Then 2-MEOH was used for functional chain transfer agent. The structure and property of the synthesized oligomers were characterized by FT-IR, FT-NMR, rheometer, and DSC. In this study, by synthetic method including the addition of 2-isocyanatoethyl methacrylate, thermal behavior of synthesized material was improved more than that reported in the previous study. Poly(methyl urethane) oligomer can be used for UV curable coatings, inks and adhesives. UV curable coating have high resistance against weather, ozone, aging, frictional wear, and heat. Besides they can absorb the shock and resist rust according to the thickness of film. It is used as an adhesive, paint, optical fiber coating agent, and waterproof agent because of these advantages at the present time.

Synthesis and Photo-Polymerization of Poly(Alkyl Urethane) Acrylate Oligomers Using 2-Isocyanatoethyl Methacrylate for UV Curable Coating

The poly(alkyl urethane) acrylate oligomers (AUAOs) were obtained by the reaction of alkyl acrylate oligomers and 2-isocyanatoethyl acrylate. Synthesis of AUAOs were done with 2-mercaptoethanol (2-MEOH), alkyl (methyl, butyl, 2-ethylhexyl) acrylate, 2,2′-azobisisobutyronitrile (AIBN, initiator) and dibutyltin dilaurate as a catalyst. Then 2-MEOH was used for functional chain transfer agent. The oligomers were characterized by FT-IR, FT-NMR, rheometer, and DSC. Each oligomer was blended and photopolymerized by UV light, and their ball tack, adhesiveness, and thermal resistance were confirmed by ball tack tester and so on. Photo-polymerized AUAOs can be used for UV curable coatings, inks and adhesives.

Tiny Particles that Make a Major Impact

Surface-modified SiO2 nanoparticles manufactured on an industrial scale are already in use in epoxy resin-based structural adhesives and in UV-cured electronic adhesives. Products of this kind have been successfully used, for example, in the Airbus A380 and in the automotive industry. This article describes the properties and mechanisms of action of the nanoparticles and also covers the current status of research and development into future adhesive applications.

UV curable adhesives provide fast, clear, bubble-free laminating to enhance LCD screens, monitors and kiosk panels

UV curable adhesives provide fast, clear, bubble-free laminating to enhance LCD screens, monitors and kiosk panels

Conductive UV Curable Adhesives for Printed RFID Antenna Structures

Summary: For the use as RFID antennas conductive adhesives were developed and investigated which are UV curable and could be applied with printing methods like offset printing or flexography. Further investigated aspects of the materials have been the range of the distance between emitter and receiver. The resulting formulations which are based on acrylates filled with silver pigments for the conductivity allow to cure layers with a thickness of up to 50 µm with a maximal volume resistance of 1.6 × 10−5 Ω/cm.

Conductive UV Curable Adhesives for Printed RFID Antenna Structures

AbstractSummary: For the use as RFID antennas conductive adhesives were developed and investigated which are UV curable and could be applied with printing methods like offset printing or flexography. Further investigated aspects of the materials have been the range of the distance between emitter and receiver. The resulting formulations which are based on acrylates filled with silver pigments for the conductivity allow to cure layers with a thickness of up to 50 µm with a maximal volume resistance of 1.6 × 10−5 Ω/cm.

Increase of the Light Extraction Efficiency in InGaN-Based Light-Emitting Diodes Integrated with Microlens Arrays Made of UV-Curable Optical Adhesive

Increase of the Light Extraction Efficiency in InGaN-Based Light-Emitting Diodes Integrated with Microlens Arrays Made of UV-Curable Optical Adhesive

A novel in situ relative-conductivity-based technique for monitoring the cure process of UV-curable polymers

The cure process of UV-curable cationic adhesives containing cycloaliphatic epoxide, oxetane, and ε-caprolactone polyol was investigated using a specially designed sensor comprising two indium tin oxide (ITO)-coated glass plates separated by a Teflon spacer, which measures the electrical conductivity and capacitance of the resin sample. The experimental results showed that, as the photoinitiator concentration increased, the relative conductivity rapidly decreased, indicating an increase in the percentage of cure conversion and the cure rate, as confirmed by photodifferential scanning calorimetry (photo-DSC) analysis. Moreover, a thinner sample and a higher UV-light intensity resulted in a shorter gelation time, a higher degree of cure and a faster cure. This novel in situ measuring technique has been proven to be reliable and effective in monitoring the cure process of UV-curable adhesives, and provides new possibilities for evaluating the curing behavior of photocurable polymers.

Synthesis and properties of poly(bisphenol A acryloxyethyl phosphate) as a UV curable flame retardant oligomer

Poly(bisphenol A acryloxyethyl phosphate) (BPAAEP) being used for UV curable flame retardant coatings and adhesives, was synthesized from phosphorus oxychloride, hydroxylethyl acrylate and bisphenol A as raw materials, and characterized using 13C NMR, 31P NMR, FTIR, MS and GPC measurements. A series of formulations with different ratios of BPAAEP to urethane acrylate, EB220, were prepared to obtain flame retardant resins. The flame retardancy of the UV cured films was investigated by the limiting oxygen index (LOI). A synergistic effect between phosphorus and nitrogen was observed when 1.5 wt% phosphorus was presented in the resin. Their maximum photopolymerization rates ( R p max ) and final unsaturation conversion ( P f) in the cured films at the presence of a 3 wt% photofragmenting initiator were investigated. The results showed that the P f increased with increasing EB220 content photo-DSC analysis. The data from dynamic mechanical thermal analysis showed that BPAAEP has good miscibility with EB220. Moreover, the crosslink density and T g of the cured film decreased along with the content of BPAAEP in the blend.

Uneven curing induced interfacial delamination of UV adhesive-bonded fiber array in V-groove for photonic packaging

The common approach to attaching a large number of fibers to a guided-wave device is to fabricate a linear array using V-grooves. UV-curable adhesives are used to attach the fiber in V-groove for the fabrication of fiber array. Interfacial delaminations at the adhesive fiber interfaces are common after the reliability test due to uneven curing of the UV adhesive. This paper investigated the causes of uneven curing that gave rise to delamination. An analytical ray tracing technique was used to estimate the variation in light intensity or shadowing during the UV curing of adhesive. These effects were found to be very severe when the refractive index difference between the adhesive and the cladding materials is very large. Based on this study, it can be concluded that the delamination problem can be minimized by selecting a UV-curable adhesive having the same refractive index of the cladding material. It is also recommended to light illuminate from the topside for fiber packaging

In-line monitoring of the conversion in photopolymerized acrylate coatings on polymer foils using NIR spectroscopy

Near-infrared (NIR) reflection spectroscopy was used to monitor the conversion of double bonds in acrylate coatings after irradiation with UV light or electron beams. Quantitative analysis of the spectroscopic data was performed either with a chemometric method on the basis of the PLS algorithm or according to the Beer–Lambert law. FTIR spectroscopy was used for calibration. In-line monitoring of the conversion in pilot-scale was carried out on clear and pigmented coatings, which were applied to polymer foils or paper by roll coating. Useful data were obtained from layers with a thickness from 4 g/m 2 upwards and at line speeds of at least up to 120 m/min. It was shown that any change of the irradiation dose or other parameters such as inertization leads to an immediate response in the conversion record. Similar investigations were also performed on layers of UV-curable adhesives on the basis of acrylic hot-melts.

Fabrication of Lateral dc Plasma Display Panels With Planar Pixel Structure

A novel lateral pixel structure where both anodes and cathodes are placed on a single plate is devised to realize monochrome dc plasma display panels. UV curable adhesives are used as the electrical insulating layers for the separation of anode and cathode addressing lines. 5/spl times/6-cm displays have been successfully fabricated on both glass and flexible substrates.

In-line determination of the conversion in acrylate coatings after UV curing using near-infrared reflection spectroscopy

Near-infrared (NIR) reflection spectroscopy was used to determine the conversion of acrylic double bonds after UV photopolymerization. Quantitative analysis of the spectra was performed with chemometric methods using FTIR spectroscopy for calibration. Moreover, it was shown that the calibration of the PLS algorithm can also be performed directly to specific properties of the coatings such as their hardness which responds extremely sensitively even to small changes of the conversion. In-line monitoring of the conversion by NIR spectroscopy was carried out for acrylate coatings with a thickness of some micrometers applied to polymer foils and panels and for thick layers of UV-curable adhesives on the basis of acrylic hot-melts. The effect of changes of the irradiation dose, the emission spectrum of the UV source and other parameters on the conversion was studied.

A study on UV-curable adhesives for optical pick-up: II. Silane coupling agent effect

Ultraviolet curable optical pick-up adhesive composites composed of acrylic and methacrylic mono-, bi- and trifunctional monomers and two kinds of urethaneacrylate oligomers have been easily prepared. In this paper, we studied the influence of various silane coupling agents to enhance the adhesion property in thermal and humid conditions by acting as both inorganic surface and organic polymer modifiers. Among them, vinyltriethoysilane (VTES) provides good adhesion effects on acrylate binder as well as silica surface. VTES added adhesives were studied by the real time FT-IR. The reliability of adhesives was explained by thermal-mechanical analysis (TMA) and then durability was tested by water boiling test. These UV-adhesives were successfully applied and settled in CD and DVD optical pick-up bodies in commercial application.

A study on UV-curable adhesives for optical pick-up: I. Photo-initiator effects

Ultraviolet curable optical pick-up adhesive composites composed of acrylic and methacrylic mono-, bi- and trifunctional monomers and two kinds of urethaneacrylate oligomers has been easily prepared by dual planetary mixer. And various fillers, thixotropic agents, antiemission and rheological additives were also used. The free radical photo-initiated polymerization reaction followed with various photo-initiators and its physical and mechanical properties were tested within 30 s of UV-irradiation. In this paper, we studied the influence of the photo-initiators and their mixtures on the polymerization rate of the adhesive compositions were studied. From these results, the mixture Irgacure 184 and Irgacure 819 provides synergic effects of surface and through curing. UV-adhesives of two types were well applied and settled in CD and DVD optical pick-up body at the reliability evaluation of Samsung Electronics’ production lines.

Comparative study of novel polymer prototype for controlled thermally reworkable UV curable acrylic adhesives in absence and presence of reactive diluent

"Comparative study of novel polymer prototype for controlled thermally reworkable UV curable acrylic adhesives in absence and presence of reactive diluent." Surface Engineering, 19(4), p. 315

Optimization and characterization of UV-curable adhesives for optical communications by response surface methodology

Novel organic UV-curable material (UCM) containing fluorine and methoxy-silane has been specifically developed for the fabrication of optical-communications systems devices. Response surface methodology (RSM) was used to evaluate the effect of UCM and colloidal silica content in UV-curable adhesive formulations on the refractive index, curing, adhesion strength (dry and wet) and coefficient of thermal expansion (CTE). A central composite design for two variables at five levels was chosen as the experimental design. UCM for all six responses was highly significant and colloidal silica was significant for conversion and adhesion strength (dry and wet). UCM and colloidal silica had significant interactive effects on adhesion strength and CTE. Based on the fitted model, in order to get the optimal conditions for the application of optical adhesives in high-performance optical components, UCM should be set over 20 wt% and colloidal silica be set below 10 wt%.

Comparative Study of Novel Polymer Prototype For Controlled Thermally Reworkable UV Curable Acrylic Adhesives in Absence and Presence of Reactive Diluent

An acrylic polypropylene oxide polymer was synthesised containing two sterically hindered urea linkages. The thermal decrosslinking behaviour of the resulting polymer matrix was studied with various basic and non-basic species. The study determined that the basic species facilitate the decrosslinking of the polymer matrix, whereas the non-basic species show no discernible decrosslinking behaviour. This study also determined that the decrosslinking behaviour of this polymer system could be controlled by the specific properties of the severing species. The work details that as the steric hindrance of the basic species increases, the decrosslinking temperature also increases. Finally, the decrosslinking properties of the polymer were studied in the presence of a reactive diluent to determine if the presence of species necessary for real adhesive formulations would impair the decrosslinking properties of the network.

Optical Measurements of Shrinkage in UV-Cured Adhesives

This paper describes an optical method that has been developed to accurately measure shrinkage during the cure of adhesives treated with UV light. The experiment was designed to measure changes in the volume of very small quantities of material appropriate to uses in the fiber-optic and micro-electronic industries. A spot-curing device (EFOS Inc.) was used to deliver a controlled exposure of UV-light with a known distribution of wavelengths to the sample. The results indicate that reproducible values for the volumetric shrinkage can be achieved using spot-curing methods. The technique described in this paper, combined with other experimental measurements under development, will assist in the selection of the appropriate adhesive for specific applications and the curing conditions needed to optimize its final properties.

A novel assembling technique for fiber collimator arrays using UV-curable adhesives

Packaging and assembly covers almost 80% of the overall cost of any fiber-optic devices. It is thus a demanding issue to lower the cost of fiber-optic alignment and attachment process. This work summarizes the results for the development of automated alignment and attachment processes for the packaging of 1/spl times/8 collimator arrays, which are critical for many photonic devices. The emphasis of this work is on the comparison of the use of three different UV-curing adhesives (Adhesives A, B, and C). It is concluded that regardless of curing shrinkage, a proper adhesive joint design can alleviate the optical loss effect of the relative fiber-lens displacement induced during curing and the subsequent cooling processes.