JPH0260940A - Antifogging of shield for helmet use - Google Patents

Abstract

PURPOSE:To form an antifogging film having a persistent antifogging effect without forming marks or unevenness on the processed surface by subjecting the inside of the title shield formed by bending a surface-hardened transparent plastic plate to a specified pretreatment, coating this surface with an antifogging agent and curing same. CONSTITUTION:A wire electrode 12 is provided inside the title shield 10 formed by bending a surface-hardened transparent plastic plate in a direction crossing the direction of bending in a position spaced from the inner surface 10a of the shield 10 by a predetermined distance t; while the wire electrode 12 is kept in a position spaced by the predetermined distance and is allowed to perform corona discharge, it is moved along the inner surface 10a of to pretreat the surface 10a; and an antifogging agent is applied to the pretreated surface 10a, and cured to form an antifogging film thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of antifogging the inner surface of a helmet shield formed by bending a transparent plastic plate with a hard surface.

[Prior Art] This type of shield uses a plastic plate with a hard surface to reduce thermal shrinkage.

Even if the antifogging agent coated on the inner surface of the shield has excellent adhesion, the antifogging effect is greatly influenced by the surface characteristics of the shield of the object to be treated, particularly the wettability. For this reason, in order to further improve the wettability of the antifogging agent to the shield inner surface, the inner surface of the shield has been roughened before being coated with the antifogging agent.

Conventional pretreatment methods include treating the shield with 5-30% NaO.
Immerse it in a H aqueous solution for about 30 minutes, and use a sponge etc. to remove the Na
After thoroughly rinsing the OH aqueous solution with water, dry it by wiping off the moisture with a soft cloth or paper. After pretreatment, an antifogging agent is applied to the inner surface of the shield and dried to harden the antifogging agent to form an antifogging film.

[Problems to be Solved by the Invention] However, the conventional method not only causes a deterioration of the working environment due to the use of an aqueous NaOH solution, but also tends to scratch the inner surface of the shield with a sponge etc. during washing, and is also difficult to clean due to manual work. However, there was a problem in that the degree of roughness of the surface, that is, the pretreatment, was likely to vary.

Furthermore, the inner and outer surfaces of the shield were exposed to Na while immersed in the NaOH aqueous solution.
There is a problem that the hardness of the inner and outer surfaces decreases due to erosion by the OH aqueous solution, and especially on the inner surface of the shield, the base on which the anti-fog film is formed is plastic that has not been hardened, which has a negative impact on the sustainability of the anti-fog effect. was.

The purpose of the present invention is to provide an anti-fog treatment for a helmet shield that can perform pre-treatment without causing scratches or unevenness on the anti-fog treated surface, has high productivity, and can improve the sustainability of the anti-fog effect. It is about providing law.

[Means for Solving the Problems] In order to achieve the above object, the anti-fog processing method of the present invention provides a helmet shield that is formed by bending a transparent plastic plate with a hardened surface. Wire electrodes were arranged at a predetermined distance from the inner surface and perpendicular to the curved direction, and while maintaining the predetermined distance, the wire electrodes were moved along the shield inner surface while causing corona discharge to pretreat the shield inner surface. Thereafter, the pretreated inner surface of the shield is coated with an antifogging agent, and the coated antifogging agent is further cured to form an antifogging film on the inner surface of the shield.

[Operation] The inner surface of the shield can be roughened uniformly and without scratches in an extremely short period of time by corona discharge from the cowire electrode, and the antifogging agent can be applied as is.

[Example] Next, an example of the present invention will be described in detail based on the drawings.

As shown in FIGS. 1 to 3, 10 is a helmet shield, which is formed by bending a transparent plastic plate with a hardened surface.

In this example, the shield 10 is made of polycarbonate with high transparency and excellent optical properties, but other resins such as polyester, polystyrene, acetyl cellulose, acrylonitrile styrene, polymethyl methacrylate, acrylonitrile butadiene styrene, etc. may also be used.

In the pretreatment of the present invention, first, a pedestal 11 having a curved portion corresponding to the outer shape of the shield 10 was prepared.

The curved surface of this pedestal 11 is covered with a high-density polyethylene thin film 1
It is composed of two layers: a thin aluminum plate 1a and a thin aluminum plate 11b. Next, after placing the shield 10 on this pedestal 11, the wire electrode 12 of the corona discharge device was placed inside the shield 10 at a predetermined distance t1, 5 mm in this example, from the shield inner surface 10a. The wire electrode 12 is approximately L-shaped, and the lower end of the electrode is directed in a direction perpendicular to the curved direction of the shield 10 (the first
(Y direction in the figure) and has a length that covers the Y direction portion of the shield 10. Next, with the wire electrode 12 corona discharged to the thin aluminum plate 11b, the shield inner surface 1 is moved in the X direction and Z direction in FIG.
0a at a speed of 1 to 2 minutes per shield.

Subsequently, an antifogging agent was applied to the shield inner surface 10a that had undergone corona discharge. In this example, the acrylic graft type polymer is blended with polyacrylate of a photopolymerizable prepolymer, a crosslinking agent, a photoinitiator of the photopolymerizable prepolymer, and an organic solvent. The antifogging agent shown was applied by a casting method.

This shield inner surface 10a is heat-treated at a temperature of 110 to 120° C. for 5 to 15 minutes to dry the antifogging agent, and then irradiated with ultraviolet rays for 3 seconds at an irradiation distance of filOcm to harden the antifogging agent.
An antifogging film having a thickness of 5 to 7 μm was formed on the shield inner surface 10a.

Next, in order to evaluate the performance of the shield of this example, the following performance test was conducted in comparison with a comparative example shield pretreated with a conventional NaOH aqueous solution.

The results are shown in Table 1. Note that the comparative example shield was antifogged in the same manner as the present example except for the pretreatment step.

(a) Adhesion test Cuts reaching the underlying plastic plate on the antifogging film were made as 11 parallel lines vertically and horizontally at 2 mm intervals, and 100 squares were cross-cut.

Next, after adhering a cellophane adhesive tape to the surface of this antifogging film, the tape was peeled off, and the number of remaining samples that did not adhere to the tape was counted and expressed with the denominator as 100.

(b) Water resistance test The shield was placed in a constant temperature oven adjusted to a temperature of 40±05℃ for 24 hours.
After standing for a period of time, the shield was removed and visually observed for abnormalities such as peeling, whitening, and cracks in the antifogging film.

(c) Pencil scratch test Pencil hardness was measured in accordance with JIS-5400.

(d) Anti-fog test The shield is cut into small pieces to form test pieces. A transparent test box with a capacity of 11,000 ml is prepared, which is partitioned into two parts on the left and right by a single partition. A part of the partition wall is cut out, and a test piece is held in the opening via a rubber seal. The left and right chambers of the test box are kept airtight from each other.

500 c/min with a metering pump to the opposite side of the test piece to the anti-fog film side.
Cooling water at a temperature of 5° C. is sent in at a flow rate of c, and the cold water is circulated so as to come into contact with the test piece. On the other hand, air containing steam heated to a temperature of 40±05°C is sent to the surface of the anti-fog film at a flow rate of 500 cc per minute using an air metering pump, and this temperature difference causes fogging on the surface of the anti-fog film. The time required for the neck phenomenon of water droplets to occur was measured.

From the results shown in Table 1, the shield of this example was significantly superior in hardness to that of the comparative example.

[Effects of the Invention] As described above, compared to conventional anti-fog processing methods, the anti-fog processing method of the present invention eliminates scratches and processing unevenness on the inner surface of the shield, thereby increasing the yield rate. Also Na OH
Since no aqueous solution is used, the hardness of the shield surface after antifogging processing, especially the hardness of the antifogging film, can be increased, and the sustainability of the antifogging effect can be increased. Furthermore, the working environment is improved and production efficiency can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pretreatment device for antifogging processing according to an embodiment of the present invention. Figure 2 is a sectional view of the main part. FIG. 3 is an external perspective view of the helmet shield. 10: Helmet shield, 10a: Shield inner surface, 12: Wire electrode. Figure 1 Figure 2

Claims (1)

[Claims] A wire electrode is arranged inside a helmet shield formed by curving a transparent plastic plate with a hardened surface at a predetermined distance from the inner surface of the shield and perpendicular to the direction of curving. , a step of pretreating the inner surface of the shield by moving the wire electrode along the inner surface of the shield while causing corona discharge while maintaining the predetermined interval; and a step of applying an antifogging agent to the pretreated inner surface of the shield. and curing the applied antifogging agent to form an antifogging film on the inner surface of the shield.