GB2289470A - Radiation-absorbing coating composition - Google Patents

Abstract

Coating composition comprises an acrylic polymer, an oxetane derivative and a UV/IR suppressing agent. The following components are specified: an acryl amide ether polymeric system, an methacrylate. HEMA polymericsystem, 1-aceton-2-ethoxetane, nitrocellulose, xylene, toluene, MIBK, BIBK, butyl acetate, IPA polymer, and SOLVESSO. Application of the coating is effected by allowing a coating liquid to flow down the surface (10) of a given substrate (e.g. glass or plastics) meanwhile causing the area of descent of the coating liquid to be expanded throughout the entire width of the surface (10) and enabling the coating liquid trickling down the surface to be collected in a reservoir (11) formed in the lower part of the surface and recovering the collected coating liquid in a tank (2) for cyclic use. <IMAGE>

Description

ULTRAVIOLET LIGHT/NEAR INFRARED LIGHT SUPPRESSING COATING AGENT FOR GLASS MATERIAL OR RESIN MATERIAL AND METHOD FOR APPLICATION THEREOF This invention relates to an ultraviolet light/near infrared light suppressing coating agent for use on glass material or resin material which, on being applied to show windows, show cases, etc. made of glass material or resin material such as acrylic or polycarbonate, effectively shields the show windows, show cases, etc. from the ultraviolet light and the near infrared light. The invention relates, in another aspect, to a method for the application of the coating agent.

The merchandise and the printed mater which are displayed inside show windows and shops are damaged by solar radiation in that it can cause discoloration and fading, and can provoke surface cracks, loss of strength, etc. The ultraviolet light falls in the range of from 300 nm to 400 nm in the spectrum of wavelengths of solar radiation. It is known that the ultraviolet light particularly of the wavelength of 360 nm degrades merchandise to the greatest extent.

The radiant heat due to near infrared radiation (800 nm to 1,100 nm) impairs the efficiency of space cooling inside shops and causes deterioration of perishable foods.

Among other ultraviolet lights, B and C ultraviolet lights (100 nm to 315 nm) are capable of causing cancer of the skin and disorders associated with fatigue. It has been the case heretofore that the B ultraviolet light is prevented from reaching the earth's surface because it is intercepted by the ozone layer occurring in the earth's atmosphere. In recent years, the ozone layer has been being destroyed by the emission of gas which has been in extensive use in human society. It has been reported in literature that even the B ultraviolet light is now reaching the earth's surface.

Heretofore, in order to prevent merchandise from being degraded by the action of ultraviolet light, and to preclude the emanation of the radiant heat from the near infrared light, the practice of applying a coating capable of intercepting the ultraviolet light and the near infrared light to the surface of show windows, show cases, etc. has been gaining in popularity. As coating materials for use in this practice, adhesive film-type materials or liquid coating agents have been widely known.

The known coating materials mentioned above intercept at most 80% of the ultraviolet light. To ensure perfect protection of the quality of merchandise from the ultraviolet light, the coating materials are demanded to effect the interception at higher proportions.

Particularly, with respect to ultraviolet light of the wavelength of 360 nm which inflicts cracks on the merchandise or causes discoloration thereof. The coating materials are required to intercept virtually all the radiation.

Further, the conventional film-type materials are not easily applied uniformly and securely to the surfaces of show windows, show cases, etc. Since the adhered surfaces can be wrinkled, the light passing therethrough is scattered on the undulating surfaces to the extent of degrading the efficiency with which the sealed surfaces intercept the radiant heat. This fact constitutes itself a drawback of the conventional film-type materials.

Furthermore, the conventional liquid coating agents show low adhesion to glass materials or the resin materials such as acrylic or polycarbonate, and are liable to result in an uneven surface on an applied layer of coating agent. Gradual separation of the applied layer can also occur with the elapse of time.

If a coating material perfectly intercepts even the visible radiation, it will deprive a room interior, for example, of the illuminance which is indispensable for human environmental quality. Thus, it must be adapted to secure necessary illuminance by reducing the proportion of interception which the coating material manifests to the visible radiation.

This invention has as its object the provision of an ultraviolet light/ near infrared light suppressing coating agent for use on a glass or a resin material, which enjoys ready applicability to the glass or resin materials, such as of acrylic or polycarbonate, adheres strongly to the material, intercepts the ultraviolet light at a ratio close to 100%, allows appropriate permeation of the near infrared light, and has a reduced ratio of interception of the visible radiation.

Another object of this invention is to provide an ultraviolet light/near infrared light suppressing coating agent for use on a glass material or a resin material which is non-toxic, waterproof and weatherproof, has a high hardness, and is able to form on a given surface an applied coating of uniform thickness and smooth finish.

To accomplish the objects described above, the ultraviolet light/near infrared light suppressing coating agent of this invention for use on a glass material comprises from 4.5% to 6.5% of an acryl amide ether system (polymer composition), from 45% to 55% of a xylene-toluene-MIBK (solvent), from 15% to 25% of solvesso 100, from 15% to 25% of 1-aceton-2-ethoxethane, and from 1.8% to 4.2% of an ultraviolet light/near infrared light suppressing agent.

By the same token, the ultraviolet light/near infrared light suppressing coating agent of this invention for use on a resin material comprises from 4.5% to 6.5% of an acryl ester DM methacrylate.-HEMA (polymer composition), from 45% to 55% of a xylene.BIBK.-butyl acetate (solvent), from 15% to 258 of 1-aceton-2-ethoxetane, from 7% to 10% of IPA (containing polymer), from 5% to 7% of nitrocellulose (0.18), and from 0.9% to 2% of an ultraviolet light suppressing agent.

In a second aspect of the invention, the method for the application of an ultraviolet light/near infrared light suppressing coating agent to a glass material or a resin material comprises causing a coating liquid 1 supplied from a tank 2 to flow through a discharge outlet 9 down the surface of a given substrate 10 so as to expand the area of flow of the coating liquid throughout the whole of the surface 10 being coated thereby coating the surface with the coating liquid, collecting the coating liquid l trickling down the lower edge of the substrate 10 being coated in a reservoir 11 formed in the lower part of the substrate 10, and recovering the collected coating liquid 1 in the tank 2 for cyclic use.

Embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a graph showing the results of a test performed on a glass plate for determination of transmittance by ultraviolet light and visible radiation with a wavelength of from 300 nm to 800 nm; Figure 2 is a graph showing the results of a test performed on a glass plate coated with the coating agent of this invention for use on a glass material for determination of transmittance by near infrared radiation with a wavelength of from 800 nm to 1,300 nm; Figure 3 is a graph showing the results of a test performed on a polycarbonate plate coated with the coating agent of this invention for use on a resin material for determination of transmittance by ultraviolet light and visible radiation with a wavelength of from 300 nm to 800 nm;; Figure 4 is a graph showing the results of a test performed on a polycarbonate plate coated with the coating agent of this invention for use on a resin material for determination of transmittance by near infrared radiation with a wavelength of from 800 nm to 1,300 nm; Figure 5 is an overall schematic diagram of an apparatus to be used for applying the coating agent of this invention; Figure 6 is an outline drawing of the apparatus illustrated in Figure 5; Figure 7 is a perspective view illustrating the discharge outlet of the apparatus of Figure 6; Figure 8 is a diagram illustrating a rotary vane and other related devices disposed in a connecting mouth of a discharge pipe; Figure 9 is a plan view illustrating the masking of an outer frame of a surface being coated by use of a curing sheet; and Figure 10 is a plan view illustrating the coating of the masked surface by use of the apparatus for application of a coating liquid according to the present invention.

Example 1: First, the ultraviolet light/near infrared light suppressing coating agent of this invention for use on a glass material will be described.

The ultraviolet light/near infrared light suppressing coating agent of this invention for use on a glass material is a liquid substance obtained by mixing from 4.5% to 6.5% of an acryl amide ether system (polymer composition), from 45% to 55% of a xylene-toluene-MIBK (solvent), from 15% to 25% of solvesso 100, from 15% to 25% of 1-aceton-2-ethoxethane, and from 1.8% to 4.2% of an ultraviolet light/near infrared light suppressing agent.

It is adapted particularly to be applied to the glass material with excellent fastness.

Now, the characteristic properties of the ultraviolet light/near infrared light suppressing coating agent of this invention for use on a glass material will be described below.

(1) Regarding transmittance The test of the coating agent for transmittance was carried out by Japan Cultural Goods Safety Testing Laboratory (juridical foundation). This test was made by a procedure which comprised applying the coating agent to the surface of a glass material in the form of a layer having a thickness of from 5 pm to 7 pm, drying the applied layer for 20 minutes, which was enough for the acquisition of resistance to touch, allowing it to stand for 48 hours and dry thoroughly, and measuring the transmittance of the dry coating by use of a spectrophotometer (produced by Shimadzu Seisakusho Limited and marketed under product code of 'MPS-5000').

In the diagrams of Figure 1 and Figure 2, the dotted lines represent the transmittance curves obtained of a glass material not using the coating agent and the solid lines represent the transmittance curves obtained of a glass material using the coating agent of this invention.

The results of this test shown in these diagrams clearly indicate that the glass material using the coating agent of this invention manifested an interception of 99.5% to the ultraviolet light of 360 nm (Point A in Figure 1), a wavelength which causes infliction of cracks or discoloration most seriously on merchandise or food, a transmission of about 60% (Point B in Figure 1) at most to the visible radiation of from 400 nm to 800 nm, and the maximum of about 80% transmittance (Point C in Figure 2) of the near infrared radiation of from 800 nm to 1,100 nm.

Incidentally, the coating agent of this invention degrades the illuminance of glass to a slight extent by intercepting the visible radiation. Since it moderates the glare of light on glass, it rather imparts to the glass material an enhanced sensation of transparency which is more comfortable to the eyes as compared with the glass material not using the coating agent.

(2) Regarding various properties such as hardness, lightfastness, and weatherability.

Table 1 given below shows the results of tests performed to determine various properties. The conditions under which the coating agent was applied to the samples of glass material subjected to the tests were the same as those used in the determination of transmittance described above.

TABLE 1

Itan of test Procedure of test Result Ultra-enargy 200 hours' (equivalent to 3 to No test 5 years' ordinary change lightfastness test) dotted Test for fast Separatiai of 100 cross-cut 100/100 adhesiveness squares (1 mm2) of sample with adhesive tape Test for 96 hours' immersion in hot Good waterproofness water at 50 C Test for 100 cycles of cleaning with No marked resistance to comm@rcially available change chemicals alkaline or weakyl alkaline detected window cleaning agent Heat cycling 10 cycles of temperature No marked changes between -20 and 60 C change detected Pencil Surface hardness tested with a 4H to 5H hardness test pencil hardness tester (3) Regarding test for solution The coating agent was tested for solution at Japan Food Analysis Center (juridical foundation). The analysis was made by the colorimetry using sodium sulphide.A sample having the coating agent applied to a surface 1 cm2 in area was kept in contact with 2 millilitres of solvent at 250C for 72 hours to allow possible solution of the applied coating into the solvent. The results of this test deny discernible solution of the applied coating.

(4) Regarding entomic sensitisation Regarding the sensitisation of insects, the ultraviolet light emitted from a fluorescent lamp illuminating displays of merchandise in a shop sensitises and attracts insects during the day as well as during the night. Particularly, in the case of shops which display foods under fluorescent light, the insects attracted to the fluorescent lamp can prejudice the hygiene of the foods displayed. In connection with this phenomenon, the fluorescent lamp demands use of an agent capable of suppressing the ultraviolet light.

A study of the relation between the ultraviolet light and the entomic sensitisation indicates that insects generally are sensitised by ultraviolet light but are not sensitised by radiation of such a long wavelength as red.

Rice stem borers (Chilo suppressails Walker), for example, manifest strong sensitivity to a wavelength zone of from 330 nm to 400 nm, particularly strong sensitivity to a wavelength of 360 nm. For the purpose of precluding the attraction of insects, therefore, ultraviolet light suppressing agents are indicated. Thus, fluorescent lamp covers coated with the coating agent of this invention which is capable of suppressing substantially 100% of the ultraviolet light from the fluorescent lamp prove to be highly effective.

The application of the coating agent of this invention to the fluorescent lamp cover of this kind ensures substantially 100% interception of the ultraviolet light emanating from the fluorescent lamp, accords effective prevention of all kinds of merchandise and all works of art from discoloration, deprives the light from the fluorescent lamp of glare and imparts thereto a luminance which is gentle to the eyes, and effects about 80% interception of the near infrared radiation emanating from the fluorescent lamp and consequently lowers the heating effect of the light and contributes effectively to the saving of energy.

(5) Regarding the saving of energy consumed for room air conditioning In an experiment carried out during the summer, the temperature in a room using untreated glass windows rose to a maximum of 320C while the temperature in direct solar radiation was 420C. When the coating agent of this invention was applied to the glass windows of the room, the temperature within the room was 29.50C at most when the temperature in direct solar radiation was 44.50C.

Thus the temperature difference outside and inside the room was 100C before the glass windows were treated and 150C after they were treated with the coating agent of this invention. This means that the coating agent intercepted the portion of the heat of solar radiation by an amount equivalent to a temperature difference of 50C.

During the night (9 o'clock pm), the temperature of the room using untreated glass windows fell from 320C to 21.50C, registering a difference of 10.50C. After the glass windows were treated with the coating agent of this invention, the temperature of the room fell from 29.50C to 240C, registering a difference of 5.50C. The results clearly indicate that the coating agent reduced the loss of heat from the room interior by an amount equivalent to a temperature difference of 50C.

Example 2: The ultraviolet light/near infrared light suppressing coating agent of this invention for use on a resin material is a liquid substance obtained by mixing from 4.5% to 6.5% of an acryl ester DM methacrylate.HEMA (polymer composition), from 45% to 55% of a xylene.BIBK.butyl acetate (solvent), from 15% to 25% of 1-aceton-2-ethoxetane, from 7% to 10% of IPA (containing polymer), from 5% to 7% of nitrocellulose (0.1%), and from 0.9% to 2% of an ultraviolet light suppressing agent. It is adapted particularly to be applied with outstanding adhesiveness to polycarbonate, a substance heretofore regarded as difficult to coat.

The characteristic properties of the ultraviolet light/near infrared light suppressing coating agent of this invention for use on a resin material will be described below.

(1) Regarding transmittance The test of the coating agent for transmittance was carried out by Japan Cultural Goods Safety Testing Laboratory (juridical foundation). This test was made by a procedure which comprised applying the coating agent to the surface of a polycarbonate plate in the form of a layer of 7 pm thickness, drying the applied layer for 10 minutes which was enough for the acquisition of resistance to touch, allowing the layer to stand for 48 hours and solidify, subjecting it to forced drying at a temperature of from 800C to 1100C (from 20 minutes to 30 minutes), allowing it to stand at room temperature for about one week and dry completely, and thereafter measuring the transmittance of the resultant dry coating by use of a spectrophotometer (produced by Shimadzu Seisakusho Limited and marketed under product code of 'MPS-5000').

In the diagrams of Figure 3 and Figure 4, the dotted lines represent the transmittance curves obtained of a resin material not using the coating agent and the solid lines represent the transmittance curves obtained of a resin material using the coating agent of this invention.

The results of this test shown in these diagrams clearly indicate that the resin material using the coating agent of this invention manifested an interception of 99.8% to the ultraviolet light of 360 nm (Point A in Figure 3), a wavelength which causes infliction of cracks or discoloration most seriously on merchandise or food, the maximum of about 85% transmission of the visible radiation of from 400 nm to 800 nm, and the maximum of about 55% interception of near infrared radiation of from 800 nm to 1,100 nm.

Incidentally, the coating agent of this invention reduces the transparency of the resin material to a slight extent by intercepting the visible radiation (near Point B in Figure 3). Since it moderates the glare, however, it rather imparts to the resin material an appearance of greater transparency which is more comfortable to the eyes as compared with the resin material not using the coating agent.

(2) Regarding various properties such as hardness, lightfastness, and weatherability Table 2 given below shows the results of tests performed to determine various properties. The conditions under which the coating agent was applied to the samples of polycarbonate plates subjected to the tests were the same as those used in the determination of transmittance described above.

TABLE 2

Item of test Procedure of test Result Test for 2000 hours' accelerated Below weatherability exposure with Sunshine #E2.0 Weather-O-Meter Test for fast Separation of 100 cross-cut 100/100 adhesiveness squares (1 mm2) with adhesive tape Test for Immersion in hot water at Good waterproofness 600C for 100 hours Test for Two hours' immersion in boiling Good resistance to water boiling water Test for 24 hours' immersion in aqueous Good resistance to 5% NaOH solution alkali Test for 24 hours immersion in aqueous Good resistance to 5% H2S04 solution acid Test for Surface hardness determined 5H hardness with a pencil hardness tester Colour hardness 5H (3) Regarding test for solution The coating agent was tested for solution at Japan Food Analysis Center (juridical foundation) in accordance with the procedure of the test for solution mentioned above. The results of this test were the same as those obtained of the coating agent used on the glass material.

The results deny discernible solution of any heavy metal.

(4) Regarding entomic sensitisation Regarding the sensitisation of insects, study results indicate that for the purpose of preventing attraction of insects, the fluorescent lamp covers coated with the coating agent of this invention which is capable of suppressing substantially 100% of the ultraviolet light from the fluorescent lamp prove to be highly effective.

The application of the coating agent of this invention for use on a resin material to fluorescent lamp covers of this kind ensures substantially 100% interception of the ultraviolet light emanating from the fluorescent lamp, and thus accords effective prevention of all kinds of merchandise and all works of art from discoloration, deprives the light from the fluorescent lamp of glare and imparts thereto a luminance gentle to the eyes, and effects about 55% interception of the near infrared radiation emanating from the fluorescent lamp and consequently lowers the heating effect of the light and contributes effectively to the saving of energy.

(5) Regarding the saving of energy consumed for room air conditioning In a test performed at 30 minutes past 1 o'clock on the afternoon of a summer day, the temperature within an outdoor telephone box made of resin reached the maximum of 43.30C before the coating agent of this invention was used on the telephone box. After the coating agent was used thereon the maximum temperature was 39.60C while the ambient temperature of the telephone box was 40.80C. This means that the coating agent of this invention intercepted the heat of radiation reaching into the interior of the resin telephone box during the day time in an amount equivalent to a temperature difference of 3.70C.

Method of Application: The method for applying the coating agents of this invention to a glass material and a resin material will be described below.

An apparatus constructed as illustrated in Figure 5 is to be used for the purpose of this application. This apparatus comprises a tank 2 for storing a coating liquid 1, a suction device 3 connected to the upper part of the tank 2, a suction pipe 4 adapted to recover the coating liquid 1 and connected to the upper part of the tank 2, connecting ports 5 formed in the lower part of the tank 2 and used to connect discharge pipes 6. Rotary vanes 8 (seen in detail in Figure 8) connected to respective motors 7 and pivotally supported inside the connecting ports 5, force the coating agent out of the ports 5 when the motor 7 is run. Discharge outlets 9 of a large width are connected to the respective leading ends of the discharge pipes 6.

In the construction described above, a removable lid 2a is set in place in the upper part of the tank 2 and a filter 2b is formed in the bottom part of the removable lid 2a. To this removable lid 2a is connected the suction pipe 4. When the removable lid 2a is tightly closed on the tank 2 and the suction device 3 is operating, negative pressure is created inside the tank 2 and a liquid can be sucked through the suction pipe 4 into the tank 2. The suction device 3 is provided with an air discharge outlet 3b.

Two discharge pipes 6 are connected to the lower part of the tank 2. The number of discharge pipes 6 does not need to be limited to two. Optionally, one discharge pipe 6 may be used instead. The rotary vanes 8 illustrated in Figure 8 are disposed inside the respective connecting ports 5 of the discharge pipes 6.

The rotary vanes 8 are rotatably supported within respective passages of the connecting ports 5 with the axes 8a thereof connected to respective electric motors 7. When the rotary vanes 8 are rotated by the motors 7, the coating liquid 1 stored inside the tank 2 is transferred via the discharge pipes 6 to the discharge outlets 9.

The apparatus described above is furnished with an electric circuit which, as illustrated in Figure 5, has an AC 100 volt power source 16 connected via a rectifier 15 to the small DC motors 7. The motors 7 are provided severally with switches 6b and the suction device 3 is provided with a switch 13.

Figure 6 represents the appearance of a preferred embodiment of the apparatus described above. The tank 2 mentioned above is fixed by a strap 21 to one lateral face bf a main casing 20 accommodating therein the suction device 3, the rectifier 15, etc. and the suction pipe 4 and the discharge pipes 6 are connected as described above to the upper and lower parts of the tank 2. At the end of each of the discharge pipes 6 remote from the tank 2, a handle 6a of a large diameter is formed as illustrated in Figure 7 to facilitate the work of application of the coating liquid. The switch 6b mentioned above is attached to the handle 6a. A discharge mouth 9 connected to the end part of the handle 6a is provided with a rectangular opening of large width such that the coating liquid 1 may be discharged over an expanded area.

When the coating agent of this invention is to be applied to the surface of a framed glass window, such as is illustrated in Figure 9, this surface 10 to be coated will be first cleaned. This cleaning is effected by wiping the surface with a detergent (methanol) thereby removing any grease film, tar (from for example cigarette smoke), and bacterial deposits. In this case, solid deposits such as silicone and putty which remain on the surface are removed with the blade of a scraper or cutter.

Then, the cleaned surface is masked as illustrated in Figure 9. A masking sheet 12 of resin material is attached by adhesive tape sequentially to the sides (1), (2), (3), and (4) of an outer frame 14 in the order mentioned with surface 10 left exposed. A reservoir 11 for collecting the coating liquid for reuse is formed as by folding upwardly the lower end of the masking sheet 12.

The end of the suction pipe 4 is inserted in the reservoir 11.

Then, the coating liquid 1 is applied to the surface 10 as illustrated in Figure 10. This application is effected by actuating the aspirating device 3 and causing the coating liquid supplied from the tank 2 and released through the discharge mouth 9 of the discharge pipe 6 to flow down the surface 10 on one lateral side of the surface 10. The discharge mouth 9 is then moved laterally in the direction of the arrow thereby enabling the area of descent of the coating liquid 1 flowing out of the discharge mouth 9 to pass across the entire width of the surface 10.

In this case, the coating liquid 1 which has flowed down into the reservoir 11 in the lower part of the masking sheet 12 is recovered into the tank 2 by virtue of the suction due to the continued operation of the suction device 3. Thus, the coating liquid 1 is cyclically reused and recovered.

Thereafter, the applied layer of the coating liquid 1 on the surface 10 is left standing until perfect solidification. Then, the adhesive tape is removed and the masking sheet 12 is removed from the outer frame 14.

In consequence of the operation described above, a very smooth coating of the coating agent having a thickness of from 5 pm to 7 pm is obtained on the surface 10 of the glass. The variation of the thickness of the applied coating is ascribable to the prevalent weather conditions on the particular date of application, the locality of the site of application, and possible changes of temperature and relative humidity of the ambient air, for example.

Claims (3)

1. An ultraviolet light/near infrared light suppressing coating agent for use on a glass material, comprising from 4.5% to 6.5% of an acryl amide ether system (polymer composition), from 45% to 55% of xylene.toluene.MIBK (solvent), from 15% to 25% of Solvesso 100, from 15% to 25% of 1-aceton-2-ethoxetane, and from 1.8% to 4.2% of an ultraviolet light/near infrared light suppressing agent.

2. An ultraviolet light/near infrared light suppressing coating agent for use on a resin material, comprising from 4.5% to 6.5% of an acryl ester DM methacrylate.HEMA (polymer composition), from 45% to 55% of xylene.BIBK.butyl acetate (solvent), from 15% to 25% of 1-aceton-2-ethoxetane, from 7% to 10% of IPA (containing polymer), from 5% to 7% of nitrocellulose (0.1%), and from 0.9% to 2% of an ultraviolet light suppressing agent.

3. A method for the application of an ultraviolet light/near infrared light suppressing coating agent for use on a glass material or a resin material, characterised by the steps of causing a coating liquid (1) supplied from a tank (2) to flow through a discharge outlet (9) down the surface of a given substrate (10) so as to expand the area of descent of the coating liquid throughout the entire width of the surface (10) being coated thereby coating the surface with the coating liquid, collecting the coating liquid (1) trickling down the lower edge of the substrate (10) being coated in a reservoir (11) formed in the lower part of the substrate (10), and recovering the collected coating liquid (1) in the tank (2) for cyclic use.