JPH0447658A - Sputter prevented fluorescent lamp - Google Patents

Abstract

PURPOSE:To facilitate film formation, provide good working effectiveness, and prevent drop of the light flux by forming a clear film of ultraviolet hardening resin of urethane acrylate containing at least two double bonds having on the outside surface of a glass tube. CONSTITUTION:4-gram coating is applied to the outside surface of a 20-watt fluorescent lamp in the form of straight tube using a clear ultraviolet hardening resin consisting of coating material compounds, which contains as chief constituent urethane acrylate including at least two double bonds having reactivity, whereto a reaction diluting agent, photo-polymerization actuating agent, and sensitiger are added. Drying process is performed at 100 deg.C for 10min, and the solvent is removed. Then the lamp is rotated at a revolving speed of 60rpm in a position 15cm apart from a high pressure Hg lamp, to irradiate the resin film on the lamp surface uniformly with ultraviolet rays, Hardening is completed by 15min. That is, urethane acrylate yields a tough and coloring-free coating film, which is in particular inevitable for a sputter preventive film, in a very short gardening time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a novel shatterproof fluorescent lamp.

Conventional fluorescent lamps are mainly composed of glass, and if they are damaged due to improper handling, glass pieces may fly off and cause personal injury. As a method for dealing with this problem, a shatterproof fluorescent lamp is known in which the outer surface of the glass tube of the fluorescent lamp is covered with a transparent synthetic resin tube. This is a tube made of heat-shrinkable polyester resin placed over a glass tube and heated to form a transparent synthetic resin coating on the outer surface of the glass tube.

Problems to be Solved by the Invention Conventional shatterproof fluorescent lamps use polyester resin tubes as described above in consideration of weather resistance, membrane strength, and the like. However, this tube is not completely transparent and has a large film thickness, which causes a major problem in that the luminous flux decreases by about 3%. In addition, the tube is extremely expensive, and it is necessary to cover the completed lamp with a polyester resin tube and heat it in a heating furnace for shrinkage treatment, which is extremely difficult to work with.

The present invention has been made to solve the above-mentioned conventional problems, and provides a shatterproof fluorescent lamp that is easy to form a coating, has good workability, and prevents a decrease in luminous flux.

Means for Solving the Problems In order to achieve this object, the shatterproof fluorescent lamp of the present invention has fewer reactive double bonds on the outer surface of the glass tube (
It has a structure in which an ultraviolet curable resin film made of a coating composition containing two urethane acrylates as a main component, to which a reactive diluent, a photopolymerizer, and a sensitizer are added is coated.

According to the present invention, the main component on the outer surface of the glass tube is made of urethane acrylate having at least two reactive double bond-containing functional groups, and a reactive diluent, a photopolymerization initiator, and a sensitizer are added to the outer surface of the glass tube. Since the ultraviolet curable resin coating is formed using the coating composition, a tough coating can be formed on the outer surface of the glass tube in a much shorter time than in the past.

EXAMPLE The biggest problem with the prior art shatterproof fluorescent lamps is that it takes a long time to form a coating, making it difficult to mass-produce. In other words, in the case of a typical straight tube 40W fluorescent lamp, it takes approximately 2 minutes to manually insert the lamp into the tube one by one, followed by an additional 3 minutes of shrinkage processing and cooling. A total of about 10 minutes was required, including 3 minutes and about 2 minutes to finish the lamp end.

As a method to solve these problems and improve mass productivity, it has been proposed to coat the outer surface of the lamp with a resin film. However, in this case, it takes 15 to 20 minutes to apply and dry the resin, and although labor can be saved, there is still a big problem in mass production. Recently, ultraviolet curable resins have been put into practical use that cause polymerization reactions with ultraviolet rays, resulting in extremely rapid curing compared to conventional heat curing. Acrylic oligomers are used. Here, oligomers refer to molecules with a molecular weight of several thousand between monomers and high molecular weight polymers. In order to apply ultraviolet curable resins to anti-scattering films, the inventors investigated various acrylic oligomers. As a result of experiments, we found that urethane acrylate is especially suitable as a shatterproof film.Urethane acrylate has the advantage of being able to produce a strong coating film that does not discolor, which is essential for a shatterproof film, in an extremely short curing time. In addition, since base resins generally have a high viscosity, UV-polymerizable, low-viscosity acrylic monomers are used to adjust the viscosity.They also absorb UV rays to generate radicals, which can be polymerized into oligomers and monomers. A photopolymerization initiator is added to cause a reaction.In order to enhance the effect of this photopolymerization initiator, an amine compound sensitizer is also added.Ultraviolet curing used in the present invention For ease of operation, the resin is preferably mixed with a solvent and used as a coating composition.Solvents include aromatic hydrocarbons such as xylene, esters such as butyl acetate, and ketones such as methyl ethyl ketone. , glycol diethers such as diethyl cellosolve can be used.

The coating composition according to the present invention is applied to the outer surface of a glass tube, and then heated and dried to remove the solvent.
A major feature is that a transparent ultraviolet curable resin film is rapidly formed by irradiation with near ultraviolet light of 00 to 400 nanometers for an extremely short period of several tens of seconds to several minutes.

Next, examples of the present invention will be described.

A transparent ultraviolet curable resin (Dainippon Ink Co., Ltd.) consisting of a coating composition whose main component is urethane acrylate containing at least two reactive double bonds, to which a reactive diluent, a photopolymerization initiator, and a sensitizer are added. Using Unidec C9-544 (manufactured by Kagaku Kogyo Co., Ltd.), 4 g was applied to the outer surface of a 20-watt straight fluorescent lamp. Drying is performed at 100° C. for 10 minutes to remove the solvent. Next, a high-pressure mercury lamp (output 80
The lamp was rotated at a rotational speed of 5 Qrpm at a position approximately 15 cm away from W/cm2, and the resin film on the lamp surface was evenly irradiated with ultraviolet rays. Curing is completed in about 15 seconds. After the lamp was completely cured, it was left for 24 hours, and then a drop strength test was conducted in which the lamp was held horizontally and allowed to fall naturally from a height of 3 m. Although the lamp was damaged, the glass pieces adhered to the coating and were completely removed. It didn't scatter. Furthermore, in an impact test, the coating did not break at all even when a 200g steel ball attached to the end of a 1m thread was applied to the lamp at an angle of 30 degrees. Then, as a result of measuring the luminous flux of the fluorescent lamp, the luminous flux of the lamp before the coating was applied was 1522 em.
(0 hours), whereas the length of the lamp with the anti-scattering film of the present invention was 1,520 (7 m), and the lamp using the conventional heat shrink tube was 1,462 em.
The fluorescent lamp of the present invention had almost no reduction in luminous flux due to the coating, and was brighter by 3% or more compared to the conventional lamp. Furthermore, when a life test was conducted, it was found that the fluorescent lamp of the present invention did not turn yellow like the conventional fluorescent lamp after being lit for 500 hours, and was found to have no problems.

Note that the ultraviolet curable resin according to the present invention is not limited to those shown in the above examples. Further, a solvent is not necessarily required, and if a solvent-free type is used, the time required for removing the solvent is not required, and further time reduction can be realized.

As explained in detail, the present invention has a method of forming an ultraviolet curable resin film mainly composed of urethane acrylate containing at least two reactive double bonds on the outer surface of a glass tube, thereby causing almost no decrease in luminous flux. , and compared to conventional heat-shrink tubes or ordinary resins applied to the outside of the lamp using a coating method, the film formation time can be significantly shortened, greatly improving mass productivity and preventing scattering. It is possible to provide a shaped fluorescent lamp.

Claims (1)

[Claims] A coating composition consisting of a urethane acrylate containing at least two reactive double bonds on the outer surface of a glass tube as a main component, and a reactive diluent, a photopolymerization initiator, and a sensitizer added to this urethane acrylate. A shatterproof fluorescent lamp characterized by a transparent ultraviolet curing resin coating.