15.11.2015
NEW CE Dental Curing Light Lamp LED-B 5W Wireless Cordless 1400mW LED-B Dental Wireless Curing Light adopts the principle of ray radiation to solidify the light-sensitive resin by shooting at it in a short time. The Lord bless you and Keep you; the Lord make his face to shine upon you and be gracious to you.
Relative to visible LEDs, UV LEDs are a quiet market at only $30 million, yet recent breakthroughs in radiant power and intensity have enabled the displacement of mercury-vapor lamps in applications including UV curing and counterfeit detection, reports LAURA PETERS. Curing involves the cross-polymerization of a photosensitive material, which can be an ink (printing), adhesive or coating, and is primarily performed at 395 nm, 385 nm or 365 nm, wavelengths which are part of the UV-A spectrum (315-400 nm). In the UV-B spectrum (280-315 nm), applications for UV LEDs include curing, medical light therapy, forensic analysis and drug discovery. Beyond these applications, UV-B radiation is known to have beneficial health properties including the natural synthesis of vitamin D in humans who are exposed to sunlight. In the lower UV-C spectral range (100-280 nm), the primary LED applications are air and water sterilization and a range of analytical tools including those that perform spectroscopic and fluorescence measurements. UV in the 250-275 nm range sterilizes water, air and surfaces by breaking-up the DNA and RNA of microorganisms and preventing their reproduction. In production curing operations, mercury-vapor lamps are hindered by short lifetime (2000-10,000 hr), slow warm-up and cool-down times, and wide spectral power distribution. The mercury lamp has a main peak at 365 nm but several smaller peaks in the visible and infrared regions (Fig. Metcalf added that many people who would not have considered UV curing because of the complexity of standard curing processes a€“ the high voltage, heat of mercury bulbs and environmental issues a€“ will now consider UV-LED curing because it subverts the traditional hassles of the old process.
UV LEDs bring such benefits as knowing precisely what power level is being delivered to the curing medium, as well as other advantages LEDs are known for, such as the ability to pulse-width-modulate the output, stated Eskow. The transition to UV LEDs also opened the door to more environmentally friendly curing formulations. For the longer-wavelength UV devices, in a similar manner to blue LED fabrication, InGaN-based epilayers are grown on sapphire substrates to produce 385, 395 and 405 nm UV LEDs for curing. In addition to producing more power, the higher-wavelength UV LEDs feature higher wall-plug efficiencies. Stacy Volk, marketing communications specialist at Phoseon Technology in Hillboro, OR, a maker of UV-LED curing systems, pointed out some of the additional advantages associated with UV-LED curing include a controlled curing intensity, scalable equipment, and the fact that the machines are smaller and compact.
One of the issues the curing industry has faced has been inconsistencies in measurement practice and parameter definitions, for example, defining radiometric intensity. Companies that manufacture UV-LED chips include Crystal IS, based in Green Island, NY (Fig.
UV-LED manufacturers focus on continually improving the efficiency and lifetime of their devices while reducing cost.
Tim Bettles, director of marketing and sales at SETi stated that its manufacturing agreement with Seoul Optodevice is designed to help SETi drive its volumes of UV LEDs and lamps higher while driving down costs. Devin Tang, marketing manager of SemiLEDs stated that the company has a full line of bare dice and surface-mount high power packaged LEDs in the 360-400-nm range.
Epigap Optronic, based in Berlin, Germany, the main distributor for Dowaa€™s UV LEDs, stated that Dowa manufactures 265, 280, 310, 325 and 340 nm bare dice or packaged LEDs. Recently, Theodore Moustakas of Boston University has pioneered the use MBE (molecular beam epitaxy) to grow more efficient (high internal quantum efficiency) UV LED devices using AIGaN-based layers on sapphire substrates.
Even though UV LED manufacturers have been working hard to improve internal quantum efficiency and optical efficiency, overall efficiency remains below 20%, meaning a great deal of heat must be dissipated from the diodea€™s junction. While some UV LED arrays are packaged on ceramic substrates, many manufacturers, particularly of single-chip devices, use TO-can type through-hole packages with a glass top that offers high transmission of UV. The choice of whether to use hermetic sealing in the package is sometimes determined by the materials in the chip.
It is important to recognize that some of the same qualities that make UV LEDs very powerful and useful a€“ their low wavelength and high energy a€“ are also the qualities that make them dangerous.
When asked to identify the key issue that might keep UV users from changing over from mercury-vapor sources to UV LEDs, many industry participants say it comes down to breaking existing industry momentum and, of course, cost. Sponsored Content is made possible by our sponsor; it does not necessarily reflect the views of our editorial staff. Subscribe to the magazine or email newsletter today at no cost and receive the latest news and information. Type I photoinitiators are unimolecular free-radical generators; that is upon the absorption of UV-light a specific bond within the initiator’s structure undergoes homolytic cleavage to produce free radicals. Type II photoinitiators require a co-initiator, usually an alcohol or amine, functional groups that can readily have hydrogens abstracted, in addition to the photoinitiator.
Once the free-radicals are generated, the polymerization mechanism is no different than any free-radical polymerization process. In UV polymerization process you have complete control over the number and rate of free-radicals generated at any point in the process. In our next post we will discuss the monomeric and oligomeric materials that utilized free-radical photoinitiators. Didn’t know what is the right experimental approach to get the right rheological information? Do you have a need for an in-situ cure monitor for a thermoset process but don’t know where to start? AbstractOrthodontic adhesive is often left on the tooth surface when a multibracket appliance is debonded, and it is difficult to remove because its colour is similar to that of the tooth.
Ultraviolet radiation is harmful to the skin and the eyes and can cause serious skin burns and eye injury either from direct or reflected radiation.
Ranging from 100 to 400 nm, the radiation can effectively be used to sterilize cosmetics, perform forensic analysis, cure materials (Fig. UV-B also accelerates the production of polyphenols in certain leafy vegetables such as red lettuce.
Specifically, 275 nm is believed to be the most effective wavelength for eradicating pathogens such as E-coli in water.
With the next generation of products that ink, coating and adhesive companies were developing, they used the opportunity to phase-out volatile organic compounds (VOCs) associated with the solvent-based formulations of past chemistries.
Metcalf describes large flat-bed banner printers as being able to use lower-power LEDs, but higher speed digital, offset and flexographic technologies require closely-spaced banks of high-flux-density LEDs.


Seoul Optodevice has a manufacturing partnership agreement with SETi, which manufactures a broad range of UV LEDs and lamps, and performs everything from wafer processing to custom lamp design.
The replacement of epoxy lenses with flat or dome-shaped glass capable of UV transmission is a relatively new development, and one that has allowed an extension of lifetimes from around 5000 hours up to as high as 30,000 hours.
The warning labels on UV LEDs and their products are clear but bear noting: UV-LEDs emit invisible ultraviolet radiation when in operation, which may be harmful to eyes or skin, even for brief periods. Lim thinks that a rounding out of the wavelength portfolio would go a long way toward adoption. There are two types of free-radical generating photoinitiators, designated as Type I and Type II photoinitiators. Homolytic cleavage is a bonding pair of electron’s even scission into to free radical products.
The highlighted bond in each species undergoes homolytic cleavage upon the absorption of UV light. The absorption of UV light by a Type-II photoinitiator causes an excited electron state in the photoinitiator that will abstract a hydrogen from the co-initiator, and in the process, splitting a bonding pair of electrons.
Benzophenone and benzophenone-type photoinitiators are the most common Type II photoinitiators. The chain propagation, termination and transfer steps found in other free-radical processes are consistent in UV polymerization. Free radicals can only be generated upon absorption of UV radiation and the source of UV radiation is defined and controlled by your process (an important subject to be discussed in a later post). Confused about what is gelation or how does vitrification impact thermoset curing profiles?
Five cases of Pseudomonas aeruginosa and 5 cases ofAcanthamoeba were identified from contact lenses or contact lens solution. If the adhesive changed colour during debonding, residual adhesive could be more easily removed. UV-LED flashlights in this range are used to detect fraudulent identification and currency, and offer the benefit of use in well-lit environments, which is difficult using a mercury-vapor lamp. He added that the UV output of a mercury vapor lamp drops off rapidly over its operational life because some of its electrode material vaporizes, depositing a film on the inside of the quartz tube which the UV cannot penetrate. A downside to these extraneous peaks is the generation of heat during printing and other curing operations. At 385 nm, this efficiency improves, but only to ~15%, making the higher-wavelength chip the better choice.
Depending on the equipment and curing application, the media can be 1 to 100 mm from the emitter window, for which AMS has produced special optics. Even though the radiation is not visible, collimating optics are utilized to deliver the radiation with a uniform power level across the target media.
The association also seeks to help speed development of applications especially suited to UV LEDs, educate researchers, integrators and end users regarding the benefits of UV LEDs, and provide a forum for industry communication and collaboration. The company provides UV emitters in hermetically-sealed metal-glass packages (TO-18, TO-39 and TO-3), with standard products and custom solutions spanning the wavelength range from 240 to 355 nm.
We are now gearing SETia€™s capacity for high-volume manufacturing to cater to new demands coming from mainstream consumer markets,a€? said Bettles. Crystal IS manufactures 260 nm UV LEDs and is the only company to produce LEDs on AlN substrates. Nonetheless, AlN substrates are only available in small sizes and remain much more expensive than sapphire wafers, thereby limiting this market.
This is only possible with an LED package capable of handling extreme power densities for the life of the product.
UV accelerates degradation of the epoxy material in a non-linear manner, directly impacting lifetime.
The new copper- and glass-based package from Schott offers the advantages of high thermal conductivity and hermeticity.
HAP’s usually absorb shorter wavelength UV-A radiation (300-350nm) while TPO’s commonly absorb radiation in the 360-400nm range, nearly into visible light.
Mechanistically, it is only the initiation process to generate free radicals that separates UV polymerization apart. If you are familiar with thermally-activated free-radical initiators, usually azo or peroxide-based initiators, you will recognize the initiator half-lives as a function of temperature provided by the manufacturer. Or wondered how to measure the glass transition temperature of an epoxy or polyester composite?
Today, as is the case with LEDs in the visible spectrum, UV LEDs are only beginning to replace the established UV sources in a likewise diverse array of markets. As a result, the user cannot easily predict the amount of UV generated at a later time; often this is a critical process parameter.
All the major providers of curing formulations (photoinitiators and resins), have recently brought higher-wavelength inks and coatings to market to fill this need. Digital inkjet curing was the first segment to adopt UV LEDs due to the required close distance to the media for the print heads to optimally perform.
Figure 6 shows examples of UV-LED arrays in lamps designed to deliver radiation in the 300-320 nm range for phototherapy applications such as the treatment of skin conditions such as psoriasis or eczema. SETi recently announced the purchase of a new facility, where it plans to manufacture over 100 million UV LEDs per year.
A thermally matched stress-free package and glass lens help eliminate common packaging failure modes associated with UV LEDs,a€? said Thomas.
It is this initiation process however that gives UV-curable resins, specifically free-radical UV-curable resins, a very unique advantage over traditional free-radical systems and that advantage is control. This half-life generally indicates the temperature at which half of the initiator molecules split to generate free-radicals with in a specific time period, usually one hour. Interestingly, we have evidence that when those plants are exposed to UV-B LEDs a short time before harvest, their polyphenol content is boosted without compromising plant mass,a€? explained Cary Eskow, global director of advanced LEDs and illumination for Avnet Electronics Marketing in Phoenix, AZ, which distributes UV LEDs.
SETi has demonstrated disinfection of drinking water in an in-line flow-through system using less than 40 mW of UV power.
He gave examples that include plastic gift cards or credit cards, which use sheet-fed lithographic printing.


This was a natural fit for UV-LED lamps as the curing intensity is highest at the emitter window. He described LED Engina€™s patented multi-layer ceramic substrate with extremely low thermal resistance that quickly conducts heat from the die junction (Fig.
Another alternative is to combine a glass lens with silicone encapsulant to accommodate even higher flux density and higher efficiency yet shorter lifetime (15,000-20,000 hr).
What this relationship implicitly implies is that at all temperatures free-radicals are generated, with lower rates of generation at low temperatures and higher rates of generation at higher temperatures – generally following the Arrhenius relationship (i.e. SBS and fluorescence intensity were examined to determine the stability of the adhesives after they were subjected to a thermal cycle test (1000 cycles).
He continued a€?This is a novel method for increasing the appeal of some foods without using chemicals. For data that were normally distributed, one-way analysis of variance followed by the Student–Newman–Keuls test was used to identify significant differences among the groups.
If the data were not normally distributed, the Kruskal–Wallis H-test followed by the Mann–Whitney U-test with Bonferroni correction was used.
While UV polymerizable resins have specific UV exposure requirements, they do not have pot-lives or freezer storage requirements – they are stable at room temperature in the absence of UV light. In ARI tests, significantly more of the adhesive with 0.003 per cent dye was left on the tooth surface after 24 hours compared with the other adhesives.
With regard to colour penetration, the adhesive with 0.003 per cent dye was five times more visible than to others.
In modern orthodontic treatment, in almost all cases, light-cured adhesive is used for bracket bonding (Krishnaswamy and Sunitha, 2007). Although brackets adhere strongly because of the improved bonding adhesives used, removal of the brackets and the cured adhesive takes considerable time.Some resin adhesive is often left on the tooth surface when the brackets are removed because the resin colour is similar to that of the tooth (Fields, 1982). Residual resin results in unaesthetic staining as well as caries at the boundary between the tooth and the residual resin (Zachrisson and Buyukyilmaz, 2005).
Terms of Sale:Refund or replacement request is available only the requests within 1 week after parcel received & returning the item as the same condition as received. To facilitate more complete removal of adhesive during bracket debonding, the focus of the present study was to find an adhesive that could be distinguished by a fluorescent colour inducible by visible light such as that from a dental curing unit.
Although fluorescent dye has been applied to a visible bonding agent for crown restoration (Tay et al., 2002), application of fluorescent dye to an orthodontic bracket adhesive has not been reported.
070522; Tokuyama dental, Tokyo, Japan)The tooth surface was treated with primer for 3–5 seconds, dried with moisture-free air and adhesive paste was applied to the bracket base.
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If the item is found non-defective, the item will be sent back to the buyer at buyer's expense.
Briefly, the separated crowns of the bovine teeth were embedded in acrylic resin, and their enamel surfaces were treated with wet 600-grit silicon carbide paper to form a flat bonding surface. The bovine teeth (n = 64) used in bond testing were randomly divided into four groups (F1, F2, F3, and control) of 16 teeth each, and each group was subsequently divided into two groups (to be tested immediately or 24 hours after curing) of eight teeth each.
Self-etching primer was applied to the prepared flat enamel surface for 3–5 seconds using a disposable applicator and was then gently evaporated in air. We do not accept any returns without an authorization number on the box or label it is being returned. About Us:We're one of the largest online dental suppliers based on many qualified manufacturers in China. We supply all dental items with very nice qualities and the best reasonable prices for worldwide dentistry students, dentists and other professionals. After bonding, the specimens were measured immediately or were stored in distilled water at 37°C for 24 hours and then measured.
However, the orthodontic adhesive exhibited increased bonding strength over a short time (e.g. Food & Drug Administration and state and local regulatory agencies.You can bid on this item if you are an authorized purchaser. The residual adhesive on each tooth was assessed using the adhesive remnant index (ARI; Artun and Bergland, 1984).
Eighteen brackets were divided into three groups (F1, F2, and F3) of six brackets each and bonded onto white acrylic plates using the respective adhesives. The brackets were then embedded in transparent epoxy resin, which was adjusted to be level with the height of the bracket to closely touch the aperture of the colour analyser.
The final finish was accomplished by grinding the top surface of the epoxy resin with 2000 grit silicon carbide paper (Figure 2). For each specimen, the colour value according to the Commission International de l’Eclairage (1978), L*a*b* colour system was measured using a colour analyser (TC-1800MKII; Tokyo Denshoku, Tokyo, Japan) without visible light irradiation.
The L* value (from 0 to 100) represents lightness and a* (from ?100 to 100) and b* (from ?100 to 100) are the chromatic coordinates of the green–red and blue–yellow axes, respectively. The epoxy resin was adjusted to be level with the height of the bracket to closely touch the aperture of the colour analyser. The final finish was accomplished using 2000 grit silicon carbide paper to grind the top surface of the epoxy resin.Thermal cycle testingTo confirm the stability of SBS and the intensity of fluorescence, thermal cycling was performed. These specimens were subjected to continuous thermal cycling for 1000 cycles between 4 and 60°C in a water bath with a 30-second dwell time in each bath. After thermal cycling, SBS tests were performed, and fluorescence intensity was measured.Statistical analysisDescriptive statistics, including the mean, standard deviation, and minimum and maximum values, were calculated for the bond strength and colour value. The Kolmogorov–Smirnov normality test was applied to the bond strength data and the colour difference Eab? data. After 24 hours, the ARI distribution of the residual F3 adhesive differed significantly from that of the control and the F1 and F2 adhesives (Table 3).



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Comments Curing light radiation spectrum

  1. JanimKa
    And putty-like, so application techniques will.
  2. Ledy_MamedGunesli
    Adhesive (LOCA) Compatible with that it cures in a very short period of time, and if you're really in a hurry.