Lighting cover

Abstract

[Problem] To provide a surface protection film which has outstanding scratch resistance and outstanding durability (environmental resistance) with respect to at least one of temperature, humidity, and chemicals, as well as a method for manufacturing the surface protection film; and to provide a lighting cover which is prevented from peeling while having the prescribed performance. [Solution] A surface protection film 1 according to the present invention is a film made of SiAlON, the SiAlON having a refractive index of 1.90-1.94, inclusive, to light having a wavelength of 550 nm. The surface protection film 1 is formed on a film forming surface M of a prism 2 by sputtering Si and sputtering Al while introducing O2 gas and N2 gas in a vacuum chamber in which the prism 2 is placed. A lighting cover C according to the present invention includes the surface protection film 1.

Description

Technical Field

[0001] The present invention relates to illumination having a protective film made of The related surface silicon nitride. On the cover

Background Art

[0002] As a surface protective film applied to a thermal head, the one described in Japanese Unexamined Patent Application Publication No. 2011-83923 (Patent Document 1) is known. This surface protective film has a silicon nitride film formed by a high-frequency (RF) sputtering method in an argon gas atmosphere mixed with 2% nitrogen gas as a surface layer.

[0003] On the other hand, as a cover for illumination (guide lights) installed on each road surface of roads and guide roads, a cover in which a coating is formed on the surface of a glass prism by vacuum deposition or the like is known. The coating on the cover is designed to have high hardness and scratch resistance while transmitting illumination light. Also, the coating is designed to withstand the environmental temperature and humidity assumed on the road surface for a long time, and also to withstand chemicals such as snow melting agents used on the road surface for a long time.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above-described surface protective film protects the surface layer of the thermal head from wear due to friction generated when a recording medium or the like passes therethrough. ​However, sialon is composed of atoms of silicon, aluminum, oxygen, and nitrogen (SiAlON), and the properties of sialon vary depending on the atomic ratio of silicon to aluminum, etc. The sialon film in the above-mentioned surface protective film is manufactured by a predetermined manufacturing method as described above and only has predetermined properties. There is room for improvement in the scratch resistance, etc. of the sialon film in the above-mentioned surface protective film.

[0006] On the other hand, there is room for improvement in the scratch resistance and environmental resistance of the coating on the cover of the induction lamp. Also, there is a possibility that the coating may peel off due to long-term use or the action of a strong impact, etc.

[0007] Therefore, the main object of the present invention There is a predetermined is to provide an illumination cover that has the performance of

Means for Solving the Problems

[0008] The invention according to claim 1 is Illumination cover wherein it is made of sialon which is The refractive index of the sialon with respect to light having a wavelength of 550 nm and is 1.90 or more and 1.94 or less includes a surface protection film and is characterized by this. The invention according to claim 2 is Illumination cover wherein it is made of sialon which is The sialon and contains aluminum in an atomic ratio of 15% or more and 32% or less includes a surface protection film and is characterized by this. The invention according to claim 3 is Illumination cover wherein it is made of sialon which is In the composition of the sialon in terms of the number of atoms, the quotient obtained by dividing aluminum by the sum of aluminum and silicon is 0.38 or more and 0.67 or less includes a surface protection film and is characterized by this. The invention according to claim 4 is Illumination cover wherein it is made of sialon which is The sialon andand contains oxygen in an atomic ratio of 7% or more and 16% or less includes a surface protection film This is what is characterized thereby. The invention according to claim 5 is Illumination cover in which it is made of sialon which is The average absorption rate of the sialon in the visible range and is 1% or less includes a surface protection film This is what is characterized thereby exists.

Advantages of the Invention

[0010] The main effect of the present invention There is a predetermined is to provide an illumination cover that has the performance of and prevents peeling.

Brief Description of the Drawings

[0011]

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Mode for Carrying Out the Invention

[0012] Hereinafter, examples of embodiments according to the present invention will be described with appropriate reference to the drawings. Note that the present invention is not limited to the following examples.

[0013] [First Embodiment] ≪Configuration of Surface Protective Film, etc.≫ As illustrated in FIG. 1, the surface protective film 1 according to the first embodiment of the present invention is formed on the film formation surface M of a glass prism 2. The prism 2 with the surface protective film 1 is used as an illumination cover C that also serves as an optical system element of a road guiding lamp (not shown) for illumination. The prism 2 is a base material on which the surface protective film 1 is formed, and in particular, when it is in a plate shape, it is a substrate. The film formation surface M of the prism 2 is the surface that is exposed when it is installed in the road guiding lamp. Note that the surface protective film 1 itself may be regarded as the illumination cover C. Also, the film formation surface M may be a surface that exceeds the exposed surface, such as the entire surface of the prism 2. One or more intermediate films may be disposed between the prism 2 and the surface protective film 1. The prism 2 may have a material other than glass. The surface protective film 1 may be formed on a portion other than the prism 2 in the road guiding lamp, or may be formed on devices, parts, members, etc. other than the road guiding lamp. For example, the surface protective film 1 may be formed on guiding lamps and displays related to automobile roads, railways (tracks), monorails, and sidewalks.

[0014] The surface protective film 1 is a film made of sialon (SiAlON). The properties of sialon change depending on the atomic number ratio of silicon and aluminum, etc. The properties of sialon approach those of silicon nitride (Si 3 N 4 ) when the number of silicon atoms increases relative to the number of aluminum atoms, and approach those of aluminum oxide (Al 2 O 3 ) when the number of aluminum atoms increases relative to the number of silicon atoms. The atomic number ratio of oxygen and nitrogen that bind changes according to the atomic number ratio of silicon and aluminum. The properties of sialon (such as the atomic number ratio of silicon and aluminum) can be changed by the type of manufacturing method and its condition setting, etc.

[0015] Figure 2 is a schematic graph showing various properties of the sialon film, with the horizontal axis representing the atomic number ratio of silicon to aluminum and the vertical axis representing the relative strength of various properties (hardness, adhesion, and chemical resistance). On the horizontal axis, the number of aluminum atoms increases relative to the number of silicon atoms as going to the left, and at the left end, it is Al 2 O 3 becomes. Also, the number of silicon atoms increases relative to the number of aluminum atoms as going to the right, and at the left end, it is Si 3 N 4 becomes. The hardness of the sialon film becomes harder (higher on the vertical axis) as the number of silicon atoms increases. The adhesion of the sialon film to the substrate is high (located above on the vertical axis) at the central part of the horizontal axis where aluminum and silicon are mixed, and is low on both sides thereof. The chemical resistance of the sialon film shows a substantially constant high level (upper side on the vertical axis) when the number of silicon atoms is equal to or more than a certain level relative to the number of aluminum atoms, and becomes lower when the number of silicon atoms is less than a certain level relative to the number of aluminum atoms. The surface protective film 1 made of sialon according to the present invention has an atomic number ratio of silicon to aluminum at which both hardness, adhesion, and chemical resistance are at a high level (refer to the good region in Figure 2).

[0016] Also, the refractive index of the sialon film changes according to the atomic number ratio of silicon to aluminum, and generally increases as the number of silicon atoms increases relative to the number of aluminum atoms. For example, a sialon film having a refractive index of 1.90 or more and 1.94 or less with respect to light having a wavelength of 550 nm corresponds to the atomic number ratio in the above-described good region, and has high levels of hardness, adhesion, and chemical resistance, and becomes the surface protective film 1 of the present invention.

[0017] ≪Manufacturing apparatus of surface protective film, etc.≫ Next, an embodiment of the apparatus for manufacturing the above-described surface protective film 1 will be described. Note that the manufacturing apparatus of the surface protective film 1 according to the present invention is not limited to the following form.

[0018] Figure 3 is a schematic top view of the manufacturing apparatus 101 according to this embodiment. The manufacturing apparatus 101 is a drum-type sputtering film-forming apparatus (carousel-type sputtering apparatus), and forms a surface protection film 1 on one side of one or more plate-shaped prisms 2. The manufacturing apparatus 101 includes a vacuum chamber 102 as a film-forming chamber, and a cylindrical drum 104 rotatably disposed around its own axis at the center thereof. On the outer peripheral cylindrical surface of the drum 104, the prism 2 to be formed with a film is held with the film-forming surface M facing outward.

[0019] A first sputtering source 110 is disposed on one surface of the vacuum chamber 102. The first sputtering source 110 includes a sputtering cathode 112 for setting a first target T1, a pair of anti-deposition plates 114, and a sputtering gas inlet 116 into which sputtering gas is introduced with an appropriate flow rate adjustment. The sputtering cathode 112 is connected to an external DC power source (not shown). The anti-deposition plate 114 is disposed so as to separate the space between the first target T1 and the portion of the drum 104 facing the first target T1 from the inner portion of the other vacuum chamber 102. The sputtering gas inlet 116 flows sputtering gas toward the space separated by the anti-deposition plate 114.

[0020] A second sputtering source 120 is disposed on another surface of the vacuum chamber 102. Similar to the first sputtering source 110, the second sputtering source 120 includes a sputtering cathode 122 for setting a second target T2, a pair of anti-deposition plates 124, and a sputtering gas inlet 126.

[0021] Furthermore, a radical source 130 is disposed on another surface of the vacuum chamber 102. The radical source 130 has a radical gas inlet 134 into which gas can be introduced with flow rate adjustment by a valve 132, and a gun 136 capable of generating plasma by applying a voltage by an acceleration voltage power source (not shown). The gas introduced into the interior of the vacuum chamber 102 from the radical gas inlet 134 is radicalized by the plasma generated by the gun 136 and irradiated in a beam shape toward the prism 2.

[0022] In addition, exhaust portions 140 are provided on both sides of the radical source 130. In each exhaust portion 140, the interior of the vacuum chamber 102 is exhausted. Note that the arrangement and the number of installations of at least any one of the first sputtering source 110, the second sputtering source 120, the radical source 130, and each exhaust portion 140 are not limited to those described above. The current (voltage) in at least any one of the first sputtering source 110, the second sputtering source 120, and the radical source 130 may be related to direct current or may be related to low-frequency or high-frequency alternating current.

[0023] An operation example of the manufacturing apparatus 101 (an example of a method for manufacturing the surface protective film 1) will be mainly described with reference to FIG. 4.

[0024] First, the prism 2 is set on the drum 104, silicon (Si) is set as the first target T1, and aluminum (Al) is set as the second target T2 (step S1). Next, the interior of the vacuum chamber 102 is evacuated (step S2). Subsequently, the drum 104 is rotated so that the prism 2 held by the drum 104 sequentially and repeatedly passes at high speed inside each of the first sputtering source 110, the second sputtering source 120, and the radical source 130 (step S3). Next, the prism 2 is cleaned (step S4). That is, oxygen (O 2With gas introduced, a high-frequency voltage is applied to the gun 136 to generate radical oxygen, which moves and irradiates the moving prism 2 for a predetermined time. Even if there are substances such as organic matter adhering to the surface of the prism 2 due to such irradiation with radical oxygen, the organic matter and the like are decomposed and peeled off by the radical oxygen and the ultraviolet rays generated by the plasma, and the surface of the prism 2 is cleaned. By such cleaning, the adhesion of the film to be formed later is improved.

[0025] Subsequently, the surface protective film 1 is formed (step S5). That is, with the rotation of the drum 104 maintained, a rare gas (here, Ar gas) is introduced from the sputter gas inlet 116 of the first sputter source 110, and a direct current (DC) voltage is applied to the sputter cathode 112. As a result, Si on the surface of the first target T1 is deposited on the surface of the prism 2 by sputtering with Ar. Also, a rare gas (here, Ar gas) is introduced from the sputter gas inlet 126 of the second sputter source 120, and a direct current voltage is applied to the sputter cathode 122. As a result, Al on the surface of the second target T2 is deposited on the surface of the prism 2 by sputtering with Ar. Furthermore, with oxygen gas (O 2 gas) and nitrogen gas (N 2 gas) introduced from the radical gas inlet 134 of the radical source 130, a high-frequency voltage is applied to the gun 136 to generate radical oxygen and radical nitrogen, which irradiate the moving prism 2 on which Si and Al are deposited, and Si and Al are oxynitrided. Incidentally, a rare gas may be introduced together with the O 2 gas and the N 2 gas. The film thickness of the surface protective film 1 is controlled by the length of the sputtering time when the input power to the sputter cathode 112 is constant and the film formation rate, which is the physical film thickness formed per unit time, is constant. Therefore, when the time corresponding to the desired film thickness has elapsed, the voltage application to the sputter cathodes 112, 122 and the gun 136 is stopped, and the formation of the surface protective film 1 is completed.

[0026] Once the formation of the surface protective film 1 is completed, the drum 104 is stopped, appropriately cooled, and then the prism 2 with the surface protective film 1 is taken out (step S6). In addition, one or more intermediate films may be further applied between the surface protective film 1 and the prism 2 by the manufacturing apparatus 101 or another apparatus.

[0027] [Second Embodiment] Next, a second embodiment of the present invention, which is the same as the first embodiment except for the surface protective film, will be described. For members and parts having the same configuration as those in the first embodiment, the same reference numerals are appropriately assigned and the description thereof is omitted. The second embodiment has appropriate modification examples similar to those of the first embodiment. As illustrated in FIG. 5, the surface protective film 201 according to the present invention is formed on the film formation surface M of the prism 2 made of glass.

[0028] The surface protective film 201 is a film including a sialon layer 204 which is a layer made of sialon and a dielectric layer 206 which is a layer made of a dielectric. The surface protective film 201 is preferably an alternating film of the sialon layer 204 and the dielectric layer 206, and more preferably an alternating film of the sialon layer 204 and one type of dielectric layer 206 made of a dielectric. The surface protective film 201 is a multilayer film including two or more layers. The number of layers of the surface protective film 201 is not particularly limited and may be either odd or even. The arrangement of each layer in the surface protective film 201 is not particularly limited, but preferably the dielectric layer 206 is the outermost layer which is the layer on the most air side (opposite side to the prism 2) in the surface protective film 201.

[0029] The material of the dielectric in the dielectric layer 206 is not particularly limited. Since the sialon has a refractive index such that the sialon layer 204 can play the role of a high refractive index layer, it is preferably at least one of a low refractive index material and a medium refractive index material. For example, the dielectric (material) is silicon oxide (SiO 2 ), calcium fluoride (CaF 2 ), magnesium fluoride (MgF 2 ​) or a mixture of two or more of these.

[0030] The total physical film thickness of each sialon layer 204 in the surface protective film 201 (when there is one sialon layer 204, the physical film thickness of the sialon layer 204) is preferably 200 nm or more from the viewpoint of obtaining better scratch resistance.

[0031] ≪Manufacture of surface protective film, etc.≫ The surface protective film 201 is formed by physical vapor deposition (Physical Vapor Deposition (PVD), vacuum evaporation, sputtering, etc.) or atomic layer deposition (Atomic Layer Deposition), etc., and preferably, in both the sialon layer 204 and the dielectric layer 206, it is sequentially formed by the same manufacturing apparatus. The sialon layer 204 is preferably formed in the above-described manufacturing apparatus 101 in the same manner as the sialon-based surface protective film 1 of the first form.

Example

[0032] Next, preferred examples of the present invention and comparative examples not belonging to the present invention will be described. Note that the present invention is not limited to the following examples. Also, depending on the understanding of the present invention, the following examples may substantially become comparative examples, or the following comparative examples may substantially become examples.

[0033] ≪Manufacturing conditions common to Examples 1 to 4 and Comparative Examples 1 to 7, etc.≫ Examples 1 to 4 and Comparative Examples 1 to 7 were each formed with the following conditions aligned by the above-described manufacturing apparatus 101. Examples 1 to 4 belong to the first form described above. That is, in Examples 1 to 4 and Comparative Examples 1 to 7, films were directly formed without an intermediate film on one side (film formation surface M) of the plate-shaped prism 2 made of white plate glass. The Vickers hardness (HVpl) of the white plate glass substrate is 646.23. The Vickers hardness of the quartz substrate is 959.93. The Vickers hardness (HVpl) here is the Vickers conversion value of the DIN standard for indentation hardness and was measured with a measuring device (HM2000LT manufactured by Fischer Instruments). The same applies hereinafter. Also, the inside of the vacuum chamber 102 was set to 2×10 -4 Pa (Pascal) at the start of film formation. Furthermore, the rotation speed of the drum 104 was set to 100 rpm (revolutions per minute). Note that the rotation of the drum 104 may be temporarily speeded up or once stopped. Furthermore, as Si of the first target T1, a material with a purity of 99.99% doped with B (boron) was used. As Al of the second target T2, a material with a purity of 99.99% was used. In addition, for O 2 gas, N 2 gas, and Ar gas, materials with a purity of 99.99% or more were used in all cases. Note that a turbo molecular pump was used in the exhaust section 140.

[0034] ≪Manufacturing conditions, etc. of Examples 1 to 4≫ Then, Examples 1 to 4 were formed under the following common conditions. That is, the flow rate of each Ar gas in the first sputtering source 110 and the second sputtering source 120 was set to 120 sccm (Standard Cubic Centimeter per Minute; 120 milliliters per minute) in all cases. Also, the flow rate of O 2 gas in the radical source 130 was set to 10 sccm in all cases, and the flow rate of N 2 gas in the radical source 130 was set to 150 sccm in all cases. Furthermore, the power in the radical source 130 was set to 1500 W (watts). Also, Examples 1 to 4 were formed under the individual conditions shown in Table 1 below.

[0035]

Table 1

[0036] That is, in the film formation of Example 1, the power of the sputter cathode 112 of the first sputter source 110 was 9000 W, and the power of the sputter cathode 122 of the second sputter source 120 was 6000 W. The film formation rate was 0.40 nm / sec (nanometers per second). Also, in the film formation of Example 2, the power of the first sputter source 110 was 4500 W, and the power of the second sputter source 120 was 6000 W. The film formation rate was 0.25 nm / sec. Furthermore, in the film formation of Example 3, the power of the first sputter source 110 was 9000 W, and the power of the second sputter source 120 was 5000 W. The film formation rate was 0.36 nm / sec. In addition, in the film formation of Example 4, the power of the first sputter source 110 was 9000 W, and the power of the second sputter source 120 was 4000 W. The film formation rate was 0.32 nm / sec.

[0037] ≪Manufacturing conditions, etc. of Comparative Examples 1 to 7≫ Also, Comparative Examples 1 to 7 were film-formed under the individual conditions shown in Tables 2 and 3 below.

[0038]

Table 2

Table 3

[0039] That is, Comparative Example 1 (Al 2 O 3In the film formation of the [film name], the first sputtering source 110 was deactivated because Si was unnecessary, except that Ar gas was introduced at 120 sccm for atmosphere adjustment in the vacuum chamber 102. Also, the power of the second sputtering source 120 was set to 6500 W, and Ar gas was introduced at 100 sccm. For the radical source 130, the power was set to 2000 W, and 2 O gas was introduced at 70 sccm, and 2 N gas was not introduced. The film formation rate was 0.38 nm / sec. Also, in the film formation of Comparative Example 2 (aluminum nitride film; AlN film), the first sputtering source 110 was deactivated in the same manner as in Comparative Example 1. Also, the power of the second sputtering source 120 was set to 6000 W, and Ar gas was introduced at 120 sccm. For the radical source 130, the power was set to 2000 W, and 2 N gas was introduced at 50 sccm, and 2 O gas was not introduced. The film formation rate was 0.29 nm / sec. Furthermore, in the film formation of Comparative Example 3 (aluminum oxynitride film; AlON film), the first sputtering source 110 and the second sputtering source 120 were the same as in Comparative Example 2. For the radical source 130, the power was set to 2000 W, and 2 O gas was introduced at 10 sccm, and 2 N gas was introduced at 100 sccm. The film formation rate was 0.26 nm / sec. Still further, in the film formation of Comparative Example 4 (silicon oxynitride film; SiON film), the power of the first sputtering source 110 was set to 9000 W, and Ar gas was introduced at 80 sccm. Also, the second sputtering source 120 was deactivated because Al was unnecessary, except that Ar gas was introduced at 100 sccm for atmosphere adjustment in the vacuum chamber 102. For the radical source 130, the power was set to 1000 W, and 2 O gas was introduced at 10 sccm, and 2 N gas was introduced at 150 sccm. The film formation rate was 0.20 nm / sec.

[0040] In addition, Comparative Example 5 (silicon nitride film; Si 3 N 4In the film formation of the film), the power of the first sputtering source 110 was set to 8000 W, and Ar gas was introduced at 100 sccm. Also, the second sputtering source 120 was made inoperative in the same manner as in Comparative Example 4, except that the flow rate of Ar gas was set to 100 sccm. Regarding the radical source 130, the power was set to 1000 W, and N 2 gas was introduced at 80 sccm, and O 2 gas was not introduced. The film formation rate was 0.20 nm / sec. Also, in the film formation of Comparative Example 6 (silicon oxide film; SiO 2 film), the power of the first sputtering source 110 was set to 9000 W, and Ar gas was introduced at 120 sccm. Also, the second sputtering source 120 was made inoperative in the same manner as in Comparative Example 4, except that the flow rate of Ar gas was set to 120 sccm. Regarding the radical source 130, the power was set to 1000 W, and O 2 gas was introduced at 100 sccm, and N 2 gas was not introduced. The film formation rate was 0.34 nm / sec. Furthermore, in the film formation of Comparative Example 7 (sialon film), the power of the first sputtering source 110 was set to 9000 W, and Ar gas was introduced at 120 sccm. Also, the power of the second sputtering source 120 was set to 3000 W, and Ar gas was introduced at 120 sccm. Regarding the radical source 130, the power was set to 1500 W, and O 2 gas was introduced at 10 sccm, and N 2 gas was introduced at 150 sccm. The film formation rate was 0.27 nm / sec.

[0041] ≪Properties, etc. of Examples 1 to 4 and Comparative Examples 1 to 7≫ The various properties of Examples 1 to 4 and Comparative Examples 1 to 7 are shown in Tables 4 to 5 below. Also, the compositions of the sialon films (Examples 1 to 4 and Comparative Example 7) are shown in Table 6 below. Furthermore, the Vickers hardness measured as described above is shown in FIG. 6. Furthermore, the transparency of the sialon films (Examples 1 to 4 and Comparative Example 7) is shown in FIGS. 7 (spectral absorption rate distribution) and 8 (average absorption rate in the visible region).

[0042]

Table 4

Table 5

[0043]

Table 6

[0044] The composition of the sialon film (SiAlON) was analyzed by energy dispersive X-ray analysis (EDX) for Examples 1 to 4 and Comparative Example 7. From this analysis, the element ratios (atomic ratios, %) of Examples 1 to 4 and Comparative Example 7 were grasped as the composition (Table 6). When the power of the second sputtering source 120 (Al power) is higher than the power of the first sputtering source 110 (Si power), that is, when Al power / (Al power + Si power) is large, the ratio of the element ratio of Al to the sum of the element ratios of Al and Si in SiAlON, that is, Al / (Al + Si), becomes large. However, due to differences in the absolute values of each power and the introduction flow rates of various gases, etc., the magnitude of Al / (Al + Si) and the magnitude of Al power / (Al power + Si power) do not have a simple proportional relationship. SiAlON characteristics approach those of Al as Al / (Al + Si) increases, and approach those of Si as Al / (Al + Si) decreases. 2 O 3 and approach those of Si as Al / (Al + Si) decreases. 3 N 4 and approach those of Si as Al / (Al + Si) decreases.

[0045] The refractive index (for light with a wavelength of 550 nm) is the smallest at 1.48 in Comparative Example 6 (SiO 2 ), and is small next in Comparative Example 1 (Al 2 O 3 ). In contrast, the refractive index of each nitride is 2.00 in Comparative Example 2 (AlN) and 2.04 in Comparative Example 5 (Si 3 N 4 ), which is higher than the others. The refractive index of SiAlON becomes 1.90 or more when Al / (Al + Si) is equal to or more than a certain level (the level of Example 4), and becomes less than 1.90 when Al / (Al + Si) is less than a certain level (less than the level of Example 4 and at the level of Comparative Example 7).

[0046] The Vickers hardness is lower (softer) than that of the quartz substrate in Comparative Example 1 (Al 2 O 3 ) and Comparative Example 6 (SiO 2 ). The Vickers hardnesses of Comparative Examples 2 to 5 exceed that of the quartz substrate, and in descending order of magnitude (hardness), they are Comparative Example 5 (Si 3 N 4 ), Comparative Example 4 (SiON), Comparative Example 3 (AlON), and Comparative Example 2 (AlN). Also, the Vickers hardness of SiAlON is approximately the same as those of Comparative Examples 3 and 4. Among SiAlON, the Vickers hardness of Example 2 is the lowest, and that of Example 1 is the highest. The Vickers hardness of SiAlON generally increases as Al / (Al + Si) decreases and approaches Si 3 N 4 . The Vickers hardnesses of Examples 1 to 4 exceed that of the quartz substrate. Therefore, Examples 1 to 4 have sufficient scratch resistance.

[0047] Regarding the transparency of SiAlON, first, by forming a thin film on the film-forming surface M of Prism 2, in the visible region and adjacent regions, the spectral transmittance distribution (horizontal axis: wavelength, vertical axis: transmittance) of Prism 2 with a sialon film becomes sinusoidal, but its central axis is horizontal, its upper limit is about 97%, and its lower limit is about 80%. Therefore, although some interference occurs in the transmitted light of Prism 2 with a sialon film, the transmittance of the transmitted light is sufficient at least in the visible region. Therefore, Prism 2 with a sialon film is sufficiently transparent to visible light and can be sufficiently used as the lighting cover C. Next, regarding the light absorption in SiAlON (the smaller the absorption, the more transparent), the absorption rate [%] can be simply expressed as "100 - (transmittance [%] + reflectance [%])", and hereinafter, with the transmittance being T and the reflectance being R, it is expressed as 100 - T - R. Therefore, in the visible region and adjacent regions, T and R were measured, and the absorption rate 100 - T - R was calculated (Figure 7). Also, the average absorption rate in the visible region was calculated (Figure 8). Here, the visible region is the wavelength range of visible light, and here it was set to be 400 nm or more and 700 nm or less. The average absorption rate exceeded 1 in Comparative Example 7, and was 1 or less in Examples 1 to 4. Therefore, the absorption of the SiAlON in Examples 1 to 4 is smaller than that in Comparative Example 7, and the transparency is higher than that in Comparative Example 7.

[0048] Furthermore, hot water tests, constant temperature and humidity tests, and chemical resistance tests were conducted on Examples 1 to 4 and Comparative Examples 1 to 7 (Table 5). Each test was conducted on a new sample on which no other tests or the like had been performed after film formation.

[0049] The hot water test was conducted as follows. That is, the sample was placed in hot water at 98 °C for 24 hours and then taken out, and the state of the sample was observed. In the hot water test, in Comparative Example 1 (Al 2 O 3 ), Comparative Example 2 (AlN), and Comparative Example 3 (AlON), film dissolution occurred. Also, in Comparative Example 5 (Si 3 N 4 ), film peeling occurred. In the hot water test, no change was observed in the films of the other Examples and Comparative Examples.

[0050] The constant temperature and humidity test was conducted as follows. That is, the sample was placed in a constant temperature and humidity chamber maintained at an air temperature of 85 °C and a relative humidity of 85% for 72 hours and then taken out, and the state of the sample was observed. In the constant temperature and humidity test, cracks occurred in the films of Comparative Example 1 (Al 2 O 3 ), Comparative Example 2 (AlN), and Comparative Example 3 (AlON). Also, in Comparative Example 4 (SiON) and Comparative Example 5 (Si 3 N 4) In Comparative Example 7, peeling of the film occurred. In the constant temperature and humidity test, no change was observed in the films of the Examples and Comparative Examples other than the above. Those in which peeling or dissolution of the film occurs in at least one of the hot water test and the constant temperature and humidity test are considered to have poor adhesion to the prism 2. Incidentally, for Comparative Example 6 (SiO 2 ) in which the Vickers hardness was not sufficient, the constant temperature and humidity test was omitted.

[0051] The chemical resistance test was carried out for the following three chemicals. The three chemicals are sodium acetate (sodium acetate), sodium formate (sodium formate), and potassium formate (potassium formate). These chemicals are used as snow melting agents on roads. The chemical resistance test was carried out in the same manner for each of the three chemicals as follows. That is, the sample was taken out after being placed in an aqueous solution of the chemical at 3% by weight at room temperature for 24 hours, and the state of the sample was observed. In the chemical resistance test, in Comparative Example 1 (Al 2 O 3 ), the film dissolved in sodium formate, and in Comparative Examples 2 (AlN) and 3 (AlON), the film dissolved in sodium formate and potassium formate. Also, in Comparative Examples 4 (SiON) and 5 (Si 3 N 4 ), peeling of the film occurred with respect to sodium acetate, sodium formate, and potassium formate. Furthermore, in Comparative Example 7, dissolution of the film occurred with respect to potassium formate. In the chemical resistance test, no change was observed in the films of the Examples and Comparative Examples other than the above for any of the chemicals.

[0052] ≪Summary of Examples 1 to 4 and Comparative Examples 1 to 7, etc.≫ Examples 1 to 4 are films made of sialon, and the refractive index of the sialon with respect to light having a wavelength of 550 nm is 1.90 or more and 1.94 or less. Examples 1 to 4 are surface protective films 1 that have sufficient Vickers hardness, sufficient scratch resistance, and sufficient transparency, and also have environmental resistance, that is, heat resistance and moisture resistance (good adhesion), as well as chemical resistance. On the other hand, Comparative Example 7 is a sialon film having a refractive index of 1.89, which is less than 1.90, and is inferior in moisture resistance and chemical resistance (formic acid Ka). Also, Comparative Examples 1 to 5 are inferior in environmental resistance (adhesion), and Comparative Examples 1 and 6 are inferior in Vickers hardness or scratch resistance. Also, Examples 1 to 4 are films made of sialon, and the sialon contains aluminum in the range of 15% to 32% in terms of atomic ratio. Examples 1 to 4 are surface protective films 1 that have sufficient Vickers hardness, sufficient scratch resistance, and sufficient transparency, and are excellent in environmental resistance. On the other hand, Comparative Example 7 is a sialon film having 10.3% of aluminum, which is less than 15% in terms of atomic ratio, and is inferior in moisture resistance and chemical resistance (formic acid Ka). Furthermore, Examples 1 to 4 are films made of sialon, and in the atomic composition of the sialon, the quotient of aluminum divided by the sum of aluminum and silicon (Al / (Al + Si)) is 0.38 or more and 0.67 or less. Examples 1 to 4 are surface protective films 1 that have sufficient Vickers hardness, sufficient scratch resistance, and sufficient transparency, and are excellent in environmental resistance. On the other hand, Comparative Example 7 is a sialon film having an Al / (Al + Si) of 0.276 (27.6%), which is less than 0.38, and is inferior in moisture resistance and chemical resistance (formic acid Ka). In addition, the sialon of Examples 1 to 4 contains oxygen in the range of 7% to 16% in terms of atomic ratio. Examples 1 to 4 are surface protective films 1 that have sufficient Vickers hardness, sufficient scratch resistance, and sufficient transparency, and are excellent in environmental resistance. On the other hand, Comparative Example 7 is a sialon film having 20.2% of oxygen, which is more than 20% in terms of atomic ratio, and is inferior in moisture resistance and chemical resistance (formic acid Ka). Also, the average absorption rate in the visible region of the sialon of Examples 1 to 4 is 1% or less. Therefore, Examples 1 to 4 are excellent in transparency.

[0053] And the lighting cover C including the surface protection film 1 of Examples 1 to 4 has sufficient Vickers hardness, sufficient scratch resistance, and sufficient transparency or light transmittance of illumination light, and is excellent in environmental resistance. For example, even when incorporated into a road guiding lamp, it can prevent the situation where small scratches (scratches) etc. occur and the cloudiness and light transmittance deteriorate, and can also withstand temperature and humidity changes and deicing agents. Also, in the surface protection film 1 of Examples 1 to 4, peeling that occurred in conventional road guiding lamps is prevented. Furthermore, in Examples 1 to 4, in the vacuum chamber 102 provided with the prism 2, while introducing O 2 gas and N 2 gas, by performing sputtering of Si and sputtering of Al, it is formed on the prism 2. Also, the sputtering of Si and the sputtering of Al are performed by applying a DC voltage. Thus, Examples 1 to 4 which are novel sialon films are actually formed.

[0054] <<Manufacturing conditions etc. common to Examples 11 to 17 and Comparative Examples 11 to 12>> Examples 11 to 17 and Comparative Example 11 were each formed into a film under the following conditions by the above-described manufacturing apparatus 101. Also, Comparative Example 12 was formed by vacuum evaporation with only the prism 2 (substrate) being the same as Examples 11 to 17 and Comparative Example 11. Examples 11 to 17 belong to the above-described second form. For clarity, Examples 5 to 10 and Comparative Examples 8 to 10 are numbered as missing. That is, Examples 11 to 17 and Comparative Examples 11 to 12 were directly formed into a film without an intermediate film on one side of a substrate made of a cycloolefin polymer (COP; "ZEONEX E48R" manufactured by Nippon Zeon Co., Ltd.). The manufacturing conditions common to Examples 11 to 17 and Comparative Example 11 were made the same as the manufacturing conditions common to Examples 1 to 4 and Comparative Examples 1 to 7, except for the material of the prism 2 (substrate). In Comparative Example 12, there are no manufacturing conditions common to others except for the substrate.

[0055] <<Manufacturing conditions etc. of Examples 11 to 17>> And Examples 11 to 17 were formed into a film under the following common conditions. That is, when forming the SiO dielectric layer 206 2 layer, the powers of the first sputtering source 110 and the second sputtering source 120 were set to 9000 W and 0 W in order, and the flow rates of each Ar gas in the first sputtering source 110 and the second sputtering source 120 were both set to 120 sccm. Also, the power of the radical source 130 was set to 1000 W, and the flow rates of Ar gas, O 2 gas, N 2 gas in the radical source 130 were set to 0 sccm, 100 sccm, and 0 sccm in order. The film formation rate in this case was set to 0.34 nm / sec. On the other hand, when forming the sialon layer 204, the powers of the first sputtering source 110 and the second sputtering source 120 were set to 9000 W and 6000 W in order, and the flow rates of each Ar gas in the first sputtering source 110 and the second sputtering source 120 were both set to 120 sccm. Also, the power of the radical source 130 was set to 1500 W, and the flow rates of Ar gas, O 2 gas, N 2 gas in the radical source 130 were set to 0 sccm, 10 sccm, and 150 sccm in order. The film formation rate in this case was set to 0.4 nm / sec. The manufacturing conditions common to Examples 11 to 17 are shown in Table 7 below. Also, the layer configurations and the physical film thicknesses of each layer of Examples 11 to 17 are shown in Tables 8 to 10 below.

[0056]

Table 7

[0057]

Table 8

Table 9

Table 10

[0058] The total number of layers of the surface protective films 201 in Examples 11 to 17 are 4, 2, 15, 10, 11, 2, and 12 in sequence. In the surface protective films 201 of Examples 13 and 15, the lowermost layer, which is the first layer (the layer closest to the substrate) counted from the substrate, is a SiO 2 layer. On the other hand, in the surface protective films 201 of Examples 11, 12, 14, 16, and 17, the lowermost layer is a SiAlON layer 204.

[0059] Example 16 is formed in a flow similar to the flow of the flowchart of the first form (Figure 4) except for step S5 (formation of the surface protective film). In step S5 of Example 14, first, the first layer of SiAlON layer 204 is formed under the above-described manufacturing conditions. The physical film thickness of the first layer of SiAlON layer 204 is adjusted by the film formation time since the film formation rate is constant at the above-described value. That is, the first layer is formed at the film formation time calculated by dividing the physical film thickness of the first layer by the film formation rate of the SiAlON layer 204. Next, the second layer of dielectric layer 206 (SiO 2 layer) is formed under the above-described manufacturing conditions. The second layer is formed at the film formation time calculated by dividing the physical film thickness of the second layer by the film formation rate of the SiO 2 layer. The surface protective film 201 of Example 12 is formed in the same manner as the surface protective film 201 of Example 16, except for the physical film thickness of each layer. The surface protective films 201 of Examples 11, 14, and 17 are formed by appropriately repeating the formation of the surface protective film 201 of Example 16.

[0060] On the other hand, the surface protective films 201 of Examples 13 and 15 are formed in the same manner as the surface protective films 201 of Examples 11, 14, and 17, except that the odd-numbered layers are SiO 2 layers and the even-numbered layers are SiAlON layers 204. In Tables 8 to 10, the physical film thickness ("total") of the surface protective film 201, the total of the physical film thicknesses of all SiO 2 layers in the surface protective film 201 ("SiO 2 total"), and the total of the physical film thicknesses of all SiAlON layers 204 in the surface protective film 201 ("SiAlON total") are shown together. Similarly, various totals are shown in Table 13 described later.

[0061] In Examples 11 and 12, the total physical film thickness (nm) of the sialon layer 204 was 104.65 and 61.35, respectively, and both were less than 215 nm. In Examples 13 to 17, the total physical film thickness (nm) of the sialon layer 204 was 585.88, 215.96, 215.96, 270.00, and 290.34, respectively, and all were 215 nm or more.

[0062] <<Manufacturing conditions, etc. of Comparative Examples 11 to 12>> On the other hand, Comparative Examples 11 to 12 were formed as follows. First, in Comparative Example 11, Si 3 N 4 layer, which is an Si 3 N 4 layer and an alternating film with an SiO 2 layer were formed under the manufacturing conditions shown in Table 11 below in the manufacturing apparatus 101. That is, when forming the Si 3 N 4 layer, the respective powers in the first sputtering source 110 and the second sputtering source 120 were 8000 W and 0 W, respectively, and the flow rates of the Ar gas in the first sputtering source 110 and the second sputtering source 120 were both 100 sccm. Further, the power in the radical source 130 was 1000 W, and the flow rates of the Ar gas, O 2 gas, and N 2 gas in the radical source 130 were 0 sccm, 0 sccm, and 80 sccm, respectively. The film formation rate in this case was 0.2 nm / sec. In addition, the SiO 2 layer of Comparative Example 11 was formed under the same conditions as when forming the SiO 2 layer in Examples 11 to 17.

[0063]

Table 11

[0064] Next, in Comparative Example 12, a TiO 2 layer, which is a TiO 2Layer and SiO 2 It is an alternating film with the SiO layer and was formed under the manufacturing conditions shown in Table 12 below by vacuum evaporation. More specifically, the vacuum evaporation is Ion Assist Deposition (IAD). SiO 2 During the film formation of the SiO layer, the voltage of the electron beam (EB) was 6 kV (kilovolts), the current was 100 mA (milliamperes), and the film formation rate was 10 Å / sec (angstroms per second). Also, the acceleration voltage of the ion beam (ion gun) was 750 V, the acceleration current was 250 mA, and the flow rate of O 2 gas supplied to the ion beam emission part was 20 sccm, and the flow rate of O 2 gas introduced into the vacuum chamber was 0 sccm (except for the above-mentioned ion beam emission part, no O 2 gas was introduced into the vacuum chamber). On the other hand, during the film formation of the TiO 2 layer, the voltage of the EB was 6 kV (kilovolts), the current was 450 mA, and the film formation rate was 3 Å / sec. Also, the acceleration voltage of the ion beam was 700 V, the acceleration current was 250 mA, and the flow rate of O 2 gas supplied to the ion beam emission part was 15 sccm, and the flow rate of O 2 gas introduced into the vacuum chamber was 120 sccm. In addition, during the film formation of any layer, the temperature in the vacuum chamber was maintained at 100 °C, and the degree of vacuum at the start of the film formation of the first layer was 8.0×10 -4 Pa.

[0065]

Table 12

[0066] The layer configurations and the physical film thicknesses of each layer of Comparative Examples 11 to 12 like this are shown in Table 13 below. The total number of layers of the surface protective films of Comparative Examples 11 to 12 was 15 and 5 in order. In the surface protective films of Comparative Examples 11 and 12, the lowermost layer was the SiO 2 layer in both cases. Comparative Examples 11 and 12 were formed under the above-mentioned manufacturing conditions.

[0067] [Table 13]

[0068] <<Properties, etc. of Examples 11 to 17 and Comparative Examples 11 to 12>> The various properties of Comparative Examples 11 to 12 and Examples 11 to 17 are shown in Table 14 below. In addition, the transparency (simulation values on a white plate glass substrate) of Comparative Examples 11 to 12 and Examples 11 to 17 are shown in FIGS. 9 to 17 (spectral reflectance distribution) in order. Furthermore, the photographs of Comparative Examples 11 to 12 and Examples 11 to 17 taken after the scratch resistance test are shown in FIGS. 18 to 26 in order.

[0069] [Table 14]

[0070] Regarding the transparency (spectral reflectance distribution), in Examples 11, 13 to 15, 17 and Comparative Examples 11 to 12, the reflectance is generally 1% or less in the visible region (here, 400 nm or more and 700 nm or less). More specifically, in the regions of Example 11 where the wavelength is 400 nm or more and less than 405 nm and where the wavelength is more than 680 nm and 700 nm or less, the reflectance slightly exceeds 1% and is 2% or less, and in the region of 405 nm or more and 680 nm, the reflectance is 1% or less. Also, in Example 17, the reflectance is 1% or less in the region of 420 nm or more and 670 nm or less, and the reflectance is 2% or less in the visible region outside that region. Furthermore, in Comparative Examples 11, 12 and Examples 13, 14, the reflectance in the visible region is 0.5% or less. Still further, in Example 15, the reflectance in the visible region is 0.5% or less except for several regions, and the reflectance in those several regions is also 1% or less. Therefore, in Examples 11, 13 to 15, 17 and Comparative Examples 11 to 12, transparency in the visible region (most of it in Example 17) is obtained. In the case of the other party, Examples 12 and 16 have a reflectance of generally 3% or less in the near-infrared region (here, 800 nm or more and 1000 nm or less). More specifically, in Example 12, the reflectance is 1% or less at 850 nm or more and 1000 nm or less, and in Example 16, the reflectance is 3% or less at 850 nm or more and 1000 nm or less. Therefore, in Examples 12 and 16, transparency in the near-infrared region is obtained.

[0071] In addition, regarding scratch resistance, the following test was conducted. That is, an abrasive (Scotch-Brite 7530DOT manufactured by 3M Japan Co., Ltd.; equivalent to #3000) was applied to the surface protective film of the sample with a load of 200 g (grams) and moved 10 times back and forth from the first end to the second end along a virtual straight line (length 20 mm (millimeters)) on the surface protective film. Then, the abrasive was removed from the surface protective film, and the surface protective film was photographed and observed. As a result of such a test, in Examples 13 to 17 (Figs. 22 to 26) and Comparative Example 11 (Fig. 18), only independent thin streak-like scratches were observed to a small extent and the number of scratches was small, and the scratch resistance was good. Also, in Examples 11 to 12 (Figs. 20 to 21), compared with Examples 13 to 17 and Comparative Example 11, the number of scratches was slightly larger and the scratch resistance was relatively average. On the other hand, in Comparative Example 12, a relatively large number of streak-like scratches were observed and the scratch resistance was inferior compared to others.

[0072] Furthermore, for Examples 11 to 17 and Comparative Examples 11 to 12, the same constant temperature and humidity test (temperature 85°C, relative humidity 85%, held for 72 hours (hr)) as in Examples 1 to 4 and Comparative Examples 1 to 7 was conducted, and after that test, the sample was further held in the same environment for 328 hours (total 400 hours) in the tank, and a long-term constant temperature and humidity test was conducted. In each constant temperature and humidity test of Examples 11 to 17 and Comparative Examples 11 to 12, in addition to appearance observation, a tape test (peel test) was conducted. That is, a cut was made with a knife along a virtual square with a side of 10 mm on the surface protective film of the sample, and an adhesive tape (Cellotape CT-15 manufactured by Nichiban Co., Ltd.) was attached to the square partitioned by the cut and peeled off vertically. In the 72-hour constant temperature and humidity test, in any of Examples 11 to 17 and Comparative Examples 11 to 12, the appearance after the test was good and peeling did not occur. On the other hand, in the long-term constant temperature and humidity test, in Examples 11 to 17 and Comparative Example 12, the appearance after the test was good and peeling did not occur, while in Comparative Example 11, peeling occurred.

[0073] ≪Summary of Examples 11 to 17 and Comparative Examples 11 to 12, etc.≫ The surface protective films 201 of Examples 11 to 17 include one or more sialon layers 204 made of sialon and one or more dielectric layers 206 made of dielectric. Therefore, a transparent surface protective film 201 excellent in scratch resistance and durability is provided. Comparative Example 11 is a multilayer film including an Si 3 N 4 layer and a dielectric layer, and peeling occurs in the long-term constant temperature and humidity test, resulting in poor durability. Further, Comparative Example 12 is a multilayer film including a TiO 2 layer and a dielectric layer, and there are many scratches in the scratch resistance test, resulting in poor scratch resistance. Further, in the surface protective films 201 of Examples 11 to 17, the dielectric layer 206 is made of SiO 2 . Therefore, the dielectric layer 206 can be formed more easily and at a lower cost as a low refractive index layer, and a transparent surface protective film 201 can be designed more easily by a multilayer film with the sialon layer 204 acting as a high refractive index layer. Furthermore, in the surface protective films 201 of Examples 13 to 17, the total physical film thickness of the sialon layers is 215 nm or more. Therefore, the number of scratches is fewer in the scratch resistance test, and the scratch resistance is further excellent.

Explanation of Reference Numerals

[0074] 1,201 ··· Surface protective film, 2 ··· Prism (substrate), 102 ··· Vacuum chamber (film deposition chamber), 204 ··· Sialon layer, 206 ··· Dielectric layer, C ··· Lighting cover.

Claims

Claim 1 An illumination cover comprising a surface protective film made of sialon, wherein the refractive index of the sialon with respect to light having a wavelength of 550 nm is 1.90 or more and 1.94 or less characterized thereby. Claim 2 An illumination cover comprising a surface protective film made of sialon, wherein the sialon contains aluminum in an atomic ratio of 15% or more and 32% or less characterized thereby. Claim 3 An illumination cover comprising a surface protective film made of sialon, wherein, in the atomic composition of the sialon, the quotient obtained by dividing aluminum by the sum of aluminum and silicon is 0.38 or more and 0.67 or less characterized thereby. Claim 4 An illumination cover comprising a surface protective film made of sialon, wherein the sialon contains oxygen in an atomic ratio of 7% or more and 16% or less characterized thereby. Claim 5 An illumination cover comprising a surface protective film made of sialon, wherein the average absorption rate of the sialon in the visible region is 1% or less characterized thereby.

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