JPS61285634A - Formation of diffusion film for tubular bulb - Google Patents

Abstract

PURPOSE:To obtain a diffusion film for a tubular bulb having no film discoloration while having a good external appearance of the film and being adequate for mass production by applying the suspension dispersed in the acryl composite particle emulsion containing colloidal silica to the inner surface of a glass globe and drying it. CONSTITUTION:For example, a material consisting of calcium phosphate (a white pigment), and the acryl composite particle emulsion (concentration of 40%) containing colloidal silica is stirred by a stirrer for 5min, followed by compounding the suspension through a sieve with 300 meshes. A white diffusion film is formed by applying 1.5g of the compounded suspension to the inner surface of a spherical transparent glass globe having the inside diameter of 10cm and drying it. Drying is performed by feeding hot wind at about 60 deg.C with wind flow of 500ml/sec into a glass globe for about 3min. Next, a bulb type fluorescent lamp is manufactured by incorporating a 13 watt type double U-shaped fluorescent lamp into the glass globe together with a stabilizer and a lighting tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of forming a diffusion film for a light bulb, particularly for a light bulb type having a light bulb base and incorporating a non-linear fluorescent lamp together with a ballast and a lighting tube. The present invention relates to a method for forming a diffusion film on the inner surface of an outer globe of a fluorescent lamp.

Conventional technology Fluorescent lamps have been used in large quantities in Japan, not only in factories and offices, but also in ordinary households, because they have much higher lamp efficiency and a longer lamp life than incandescent lamps. Ta. However, most fluorescent lamps have a linear or annular shape, which means they are larger than light bulbs and require ballasts and lighting tubes, making the entire device large and difficult to handle. Their major drawback is that they are more complicated than light bulbs. In recent years, in order to solve the drawbacks of fluorescent lamps and to save power, fluorescent lamps have been molded into an iU shape or double υ shape and integrated with a lighting tube and ballast to form a glass globe. A so-called bulb-shaped fluorescent lamp has been proposed. In this case, the inner surface of the glass globe is usually coated with a white pigment so that the light from the built-in fluorescent lamp is uniformly diffused.

An example of a method for applying this white pigment is a wet coating method that uses a suspension of a white pigment conventionally used in fluorescent lamps, etc. in an organic solvent containing a binder, such as nitrified cotton. Are known.

Further, there are already known methods in which water is used instead of the organic solvent and an aqueous polymer is used as the binder.

Problems that the invention aims to solve However, in the case of the coating method using a suspension that uses nitrified cotton as a binder, if the light is turned on for a long time, the ultraviolet rays emitted from the fluorescent lamp housed inside the glove will cause the problem. in,
It was discovered that the entire white diffusion film turned yellow, resulting in poor appearance and a significant decrease in luminous flux. In addition, products that use water-soluble polymers as a binder and water as a dispersant have strong foaming properties, and it has been found that they have the disadvantage of frequently causing poor membrane appearance due to the generation of bubbles during mass production. None of the methods could be implemented into a mass production process.

The present invention provides a method for forming a diffusion film for a bulb, which does not cause discoloration of the film, has a good appearance, and is suitable for mass production.

Means for Solving the Problems The present invention is characterized by a method for forming a diffusion film for a bulb, in which a suspension in which a pigment is dispersed in an acrylic composite particle emulsion containing colloidal silica is applied to the inner surface of a glass globe and dried. It is something to do.

Function When using the wet coating method, the important points are the selection of a solvent that has good pigment dispersibility, the selection of a binder that will not change color even when exposed to ultraviolet rays for a long time, and the use of a water-soluble polymer as a binder. If so, choose one with low foaming properties. The inventors investigated various binders and found that an acrylic composite particle emulsion containing colloidal silica was suitable. Acrylic composite particle emulsion containing colloidal silica is not simply a mixture of colloidal silica and acrylic resin, but the emulsion particles have a two-layer structure, with colloidal silica localized in the center and acrylic resin in the periphery. Because it has a novel structure in which colloidal silica and acrylic resin are distributed, it has superior water resistance, adhesion, heat resistance, and weather resistance compared to a simple mixture of colloidal silica and acrylic resin, and has better foaming properties than previously known. It has the characteristic of being significantly less foaming than vinyl acetate emulsion, which is a typical emulsion. In other words, the film formed by drying is completely insoluble in water, so even if moisture adheres to it, the film will not fall off at all.
It was also found that it has excellent weather resistance and does not discolor at all even when exposed to ultraviolet rays emitted from a fluorescent lamp for a long period of time.

Example Examples of the present invention will be described in detail below.

Example 1 Calcium sinate (white pigment) 6.6 kg
Acrylic composite particles containing colloidal silica Emulsilon (
40% concentration)...3.4 kg The above materials were stirred for 5 minutes using a stirrer, and then passed through a 300 mesh sieve to prepare a suspension. Using the prepared suspension, 1.5 dah was coated on the inner surface of a spherical transparent glass globe with an inner diameter of 10 alt, and dried to form a white diffusion film. Drying was carried out by blowing warm air at about 60° C. at a flow rate of 500 ml for 7 seconds into the glass globe for about 3 minutes. Next, a 13-watt double U-shaped fluorescent lamp was assembled together with a ballast and a lighting tube into a glass globe to produce a complete light bulb-shaped fluorescent lamp. Even when this lamp was lit for 6,000 hours, no film came off at all, and no discoloration of the film occurred.

Example 2 Barium carbonate (white pigment) 5.2 kg colloidal silica-containing acrylic composite particle emulsion (40
% concentration)...4.8 kg of the above materials were placed in a ball mill pot, and ball milled for 6 hours. After completing the ball mill, 2. After coating and drying, a white diffusion film was formed.

Drying was carried out by blowing warm air at about 80'C and a flow rate of 5 onl/sec into the glass globe for about 2 minutes. Next, a 13 Watt double U-shaped fluorescent lamp was assembled with a ballast and a lighting tube into a glass globe to produce a light bulb-shaped fluorescent lamp. Even after lighting for 6,000 hours, no film detachment occurred, and no discoloration of the film was observed.

Example 3 Nickel titanate (yellow pigment) 7 kg colloidal silica-containing acrylic composite particle emulsion (40
% concentration]...3kQ The above materials were placed in a ball mill pot and ball milled for 20 hours. After completing the ball mill, 1.
It was coated for 8y and dried to form a yellow diffusion film. Drying is about 6
The test was carried out by blowing warm air at 0°C and a flow rate of 60Oml/sec into the glass globe for about 3 minutes. Next, a 13-watt double U-shaped fluorescent lamp was assembled in a glass globe together with a ballast and a lighting tube to produce a light bulb-shaped fluorescent lamp. Even after the lamp was turned on for eooo hours, no film came off at all, and no discoloration of the film was observed.

Incidentally, one of the features of the present invention is that the incidence of film appearance defects due to foaming during mass application is extremely low. Example 1 and 2
When comparing the film failure rate with that when applied with
The results shown in the table below were obtained.

The mixing ratio of X vinyl acetate emulsion suspension is as follows.

Even if pigments other than Examples 1 to 3 were used, the number of occurrences of poor film appearance due to bubble generation remained basically the same;
It was confirmed that the number of films with defective film appearance per 00 films was 10 or less.

As described in detail, the present invention provides a diffusion film formed on the inner surface of a glass globe, which has excellent effects such as no discoloration, very little occurrence of film appearance defects even when applied in large quantities, and high film adhesion strength. It is possible to provide a method for forming a diffusion film for a bulb having the following properties.

Claims (1)

[Claims] A method for forming a diffusion film for a bulb, comprising applying a suspension in which a pigment is dispersed in an acrylic composite particle emulsion containing colloidal silica to the inner surface of a glass globe and drying it.