JPS5910943B2 - Method for improving wetting properties of polyurethane-coated glass surfaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the wetting properties of a polyurethane-coated glass surface, which can provide a polyurethane-coated glass surface with excellent wetting properties for water, aqueous solutions, and the like.

In recent years, a method has been developed in which the surface of a glass container for bottling beer, soft drinks, etc. is coated with a plastic film for the purpose of preventing the glass container from bursting or scattering when broken.

However, unlike glass, plastic films have strong water repellency, and when they get wet with water, aqueous solutions, etc., there is a problem in that the water on the glass surface condenses in the form of water droplets, giving an appearance similar to oil stains. In addition, depending on the ambient temperature, it is difficult to observe the internal condition of bottles due to condensation and cloudiness, so visual inspection of the cleanliness of bottles before bottling is carried out by pouring shower water onto the bottle surface. Special measures are required to do this. Therefore, the present inventors conducted various studies with the aim of solving the above-mentioned problems and improving the wetting characteristics of the 15 plastic-coated glass surface. As a result, the present inventors applied an artificial ultraviolet light source to the glass surface coated with a specific polyurethane film. The present invention was achieved based on the discovery that a polyurethane-coated glass surface having wettability comparable to that of a glass surface can be obtained by irradiating ultraviolet rays using a polyurethane resin.

Therefore, the method of improving the wettability of a polyurethane-coated glass surface according to the present invention involves irradiating the glass surface coated with a polyester-based polyurethane film with ultraviolet rays using an artificial ultraviolet 25 radiation source to modify the surface of the polyurethane film itself. It is characterized by the following.

According to the present invention, a plastic-coated glass surface with wettability comparable to that of a glass surface can be obtained.30 This does not show water-resistance immediately after washing with a washing machine, etc.; It can be used in the same way, and it also has the inherent effects of preventing bottle breakage and scattering, so it has great benefits in terms of use.

In addition, if the water repellency is improved by ultraviolet irradiation, 35
Even if exposed to the weather for a long time, it no longer becomes water repellent,
The improved condition is maintained. Furthermore, according to the present invention, it is possible not only to improve the water repellency of the surface of newly created unused polyurethane-coated glass (so-called preventive effect), but also to improve the water repellency of the surface of glass recovered after use. It can also be improved (so-called therapeutic effect). The polyurethane-coated glass surface in the present invention can have an appropriate shape such as a glass bottle.

As the polyurethane, for example, a polyether polyurethane made from a polyisocyanate such as hexamethylene diisocyanate or xylylene diisocyanate and a polyol such as polyoxypropylene glycol is used. The water repellency of polyester polyurethane is significantly improved by UV irradiation. As an artificial ultraviolet source,
For example, suitable ones such as sterilizing ultraviolet lamps, ultraviolet fluorescent lamps, xenon lamps, and high-pressure mercury lamps can be used, and high-pressure mercury lamps are particularly suitable.

Irradiation of ultraviolet rays from an artificial ultraviolet source is carried out, for example, by placing the object to be irradiated at an appropriate distance from the ultraviolet source, and in the case of a bottle or the like, by rotating the object or by placing ultraviolet sources on all sides.

Irradiation conditions are 1kW to 465 when unused (prevention)
30 minutes from a distance of 45cm using a high-pressure mercury lamp (0.5kW
time) or more preferably 60 minutes (1.0kW hour) or more, 4k
W-25C! ! It is sufficient to use a 15W-36α germicidal lamp for 10 minutes (at 0.67kW) or more from a distance of 45CTfL with a 15W-36α germicidal lamp for 10 minutes or more (at 0.67kW) with a 15W-36α germicidal lamp.
4 to 6 days from a distance of 5 crfL (1.5 to 2.2 kW
time), 1kW-46α high pressure mercury lamp for more than 15 minutes, 4k
The improvement effect can be seen in 10 minutes (at 0.67 kW) or more, preferably 15 minutes or more, from a distance of 45 cwL using a W-25α high-pressure mercury lamp. Although the above conditions are for room temperature irradiation, the irradiation time can be significantly shortened by heating the glass surface to 80 to 160°C, preferably 100 to 140°C, before irradiation. If the temperature is below the above range, it is difficult to achieve a good heating effect, and if the temperature is above the above range, there is a risk of deterioration of the polyurethane resin. The effect of improving water repellency by UV irradiation is that the shorter the elapsed time after coating with the polyurethane film, the shorter the exposure period, and of course the closer the irradiation is, the shorter the UV irradiation time will be. Moreover, too much irradiation may cause deterioration of the resin.

The effect of improving wettability due to ultraviolet irradiation is suppressed if an alkali is attached to the film during irradiation, and promoted in acidic conditions. The reason why the wetting properties of polyurethane films are improved by ultraviolet irradiation treatment is not yet clear, but the oxidative polymerization of polyurethane progresses due to ultraviolet photons, and the surface becomes thinner, albeit slightly. Apparent increase in hydrophilicity, reactant isocyanate (unreacted product or product decomposed by ultraviolet rays)
The carboxyl group of is excited by a photon and abstracts a hydrogen atom from another reactant, a polyol, to form a hydroxide-containing compound. It is conceivable that the number of hydrophilic groups increases due to a so-called photoreduction reaction. The present invention will be further explained below with reference to Examples.

Example 1 A vinyl coated bottle whose top layer was coated with a polyester-based polyurethane film was placed on a rotary table rotating at 20 revolutions per minute, and the temperature was 45 C! from the surface of the bottle. ! 4kW-25c1 on all sides of L position
A high-pressure mercury lamp for photochemistry was placed and irradiation was performed for 10 minutes.

Even though the obtained irradiation-coated bottles were passed through the bottling product process 20 times, the surface of the bottles after washing remained well wet and there was no condensation, and as with uncoated glass bottles, there was no problem during bottle inspection. There were no problems.

Further, even after six months of weathering, water repellency and dew condensation did not occur. On the other hand, polyurethane-coated bottles that were not irradiated with ultraviolet rays were passed through the bottling product process 20 times.
As the number of passes increases, the water repellency on the surface of the bottle after washing increases, and dew condensation begins to form. After the 10th time, bottle inspection becomes difficult, and if exposed for a long period of time, the bottle becomes water repellent and becomes condensing. Ta. The unirradiated polyester-based polyurethane-coated bottle that has passed through the above bottling product process 20 times is placed on a rotary table that rotates at 20 revolutions per minute in the same manner as above in order to improve its deteriorated water retraction properties, and the bottle is placed on a rotary stand that rotates at 20 revolutions per minute, 45° below the surface of the bottle. 4kW-25 on all sides of the position? When a high-pressure mercury lamp for photochemistry was placed and irradiation was performed for 10 minutes, a similar effect of improving water repellency was obtained.

Example 2 The surface of a coated beer bottle whose top layer was coated with a polyester-based polyurethane film was heated at 120°C immediately after the coating, and ultraviolet rays were irradiated from all sides at a position 30 cm from the bottle surface in the same manner as in Example 1. The same water-receiving property improvement effect as in Example 1 was achieved after irradiation for 1 minute.

Reference example 1 A 4kW ultraviolet lamp is applied to a nylon 12 coated bottle at 45C.
! Irradiation was performed from a distance of 7L for 15 minutes, and the bottles after irradiation were passed through the bottling product line seven times.

In other words, the bottle was washed with an alkaline aqueous solution seven times. The contact angle before irradiation was 49.10', while the contact angle after one pass through the bottled product line was 50.20'.
However, no effect of improving water repellency by irradiation was observed. Reference Example 2 Various types of polyurethane were coated on the surface of a glass plate, and 4kW ultraviolet rays were irradiated between two powders from a position of 45c1n.

Thereafter, the same washing with an alkaline aqueous solution as above was carried out twice. The results were as follows.

Claims (1)

[Scope of Claims] 1. Wetting properties of a polyurethane-coated glass surface, characterized in that the glass surface coated with a polyester-based polyurethane film is irradiated with ultraviolet rays using an artificial ultraviolet source to modify the surface of the polyurethane film itself. How to improve. 2. The method for improving the wettability of a polyurethane-coated glass surface according to claim 1, wherein the glass surface coated with a polyester-based polyurethane film is irradiated with ultraviolet rays using an artificial ultraviolet source at room temperature. 3. Wetting properties of a polyurethane-coated glass surface according to claim 1, wherein the glass surface coated with a polyester-based polyurethane film is heated to 80 to 160°C and then irradiated with ultraviolet rays using an artificial ultraviolet source. How to improve.