HK1105024B - Optical article and manufacturing method of the same - Google Patents

Description

Optical article and method for manufacturing the same

Technical Field

The present invention relates to an optical article having a functional film (functional layer) such as an antireflection layer on an optical substrate made of glass or plastic, and a method for producing the same.

Background

In the production of various optical articles, various functional films (functional layers) including a hard coat layer, a colored layer, an antireflection layer, and an antifouling layer are directly formed on an optical substrate made of glass or resin, or a primer layer is interposed between the functional films and the optical substrate. In addition, in the process of manufacturing a spectacle lens or other optical articles, an antireflection layer is directly formed on an optical substrate made of glass or resin or a hard coat layer is interposed between the antireflection layer and the optical substrate or a primer layer and a hard coat layer are interposed, thereby suppressing light reflection and improving light transmittance. One embodiment of the antireflection layer is an antireflection layer having a multilayer structure formed by stacking a low refractive index sublayer and a high refractive index sublayer. Suitable materials for forming the low-refractive-index sublayer are SiO₂Or SiO_xIsosilica, or MgF₂. Is suitable for being used as a structureThe material forming the high-refractive-index sub-layer being ZrO₂、Ta₂O₅、TiO₂、CeO₂Or Y₂O₃And the like. The anti-reflective layer may also comprise Al₂O₃Or CeF₃Etc. of the intermediate refractive index sublayers.

In the formation of a functional thin film and an antireflection layer having a multilayer structure, a vacuum evaporation method is often used in which a substance constituting a thin film or a substance constituting each sub-layer is heated and evaporated by a method such as an electron gun or resistance heating under vacuum conditions and laminated on an optical substrate.

Patent document 1 discloses a film forming apparatus having three chambers, wherein a third chamber is used to form an antifouling layer on an antireflection layer. After the optical substrate is placed in the first chamber, the antireflection film is evaporated in the second chamber, and the antifouling layer is formed on the antireflection film in the third chamber.

In order to maintain a good state of a surface having a large influence on optical characteristics of an optical article, it is important to improve durability, particularly scratch resistance, of an anti-reflection layer having a multilayer structure. In semiconductor optical components such as image sensors, a silicon nitride thin film is known as a material having high durability and high light transmittance.

Patent document 2 discloses the following: the silicon nitride thin film is formed by irradiating the substrate with nitrogen ions simultaneously with vacuum deposition of silicon, or by alternately performing vacuum deposition of silicon and irradiation of nitrogen ions. The silicon nitride layer has superior light transmittance, and thus, the silicon nitride layer may be used as one of sub-layers of an anti-reflection layer having a multi-layer structure. The antireflection layer is required to be formed into a uniform layer with a predetermined thickness in order to obtain a desired optical effect. However, it is difficult to stably form a silicon nitride layer. Therefore, in the method disclosed in patent document 2, it is required to accurately control the deposition rate of silicon and the irradiation amount of nitrogen ions.

Patent document 1: japanese unexamined patent application publication No. 2005-187936

Patent document 2: japanese unexamined patent publication No. 5-214515

In addition, there have been some optical designs of antireflection layers using a low refractive index layer and a high refractive index layer having the above-mentioned compositions, which are designed to obtain an optical system having high transmittance. However, the refractive index of the silicon nitride layer is different from that of the layer having the above composition. The silicon nitride layer basically has a high refractive index, but its refractive index is different from those of other layers having a high refractive index, and therefore, it is necessary to design a new optical system.

In addition, when a silicon nitride layer is used as the high refractive index layer, it is presumed that an interface portion between the silicon nitride layer and the silicon dioxide layer used as the low refractive index layer becomes SiON_xSuch a composition state. It is difficult to control the refractive index of the layer including the interface portion and the film thickness corresponding to the refractive index. For example, Si₃N₄Has a high refractive index of about 2.05, however, if Si is used₃N₄Layer and SiN_xO_yAnd SiO₂When the two materials coexist, the refractive index is in the range of 1.45-2.05. It is believed that the durability of the anti-reflective layer comprised of the silicon nitride sublayer and the silicon dioxide sublayer is greatly improved. However, it is difficult to manufacture an anti-reflection layer having sufficient optical characteristics.

In addition, in order to maintain a surface of an optical article, which has a large influence on optical characteristics, in a good state, it is very important to design a functional film for improving durability, particularly scratch resistance. In semiconductor optical components such as image sensors, a silicon nitride thin film is known as a material having high durability and high light transmittance.

Typically, a thin film of silicon dioxide is formed on an optical substrate, either alone or as part of a multilayer film. In particular, when the optical substrate is a resin, the weak scratch resistance of the silica thin film also affects the durability of the optical substrate.

The silicon nitride film can improve the scratch resistance of the silicon dioxide film. Patent document 2 discloses the following: the silicon nitride thin film is formed by irradiating the substrate with nitrogen ions simultaneously with vacuum deposition of silicon, or by alternately performing vacuum deposition of silicon and irradiation of nitrogen ions. However, it is difficult to stably form a silicon nitride thin film. In the method disclosed in patent document 2, it is required to accurately control the deposition rate of silicon and the irradiation amount of nitrogen ions.

Disclosure of Invention

One aspect of the present invention is to provide an optical article including an optical article. The optical article has a layer including a nitrided portion, the nitrided portion being a surface of the layer on a side facing away from the optical substrate, the layer being in SiO_xIs a main component and is formed directly on the optical substrate or with at least one other layer sandwiched between the layer and the optical substrate.

Since the optical article includes the layer including the nitrided portion, which is the surface of the layer on the side opposite to the optical substrate, the durability, particularly the scratch resistance, of the layer including the nitrided portion can be improved by using such an optical article.

In this optical article, the main component of the nitrided portion is Si_sO_tN_u(s>0，t≧0，u>0)。

As one form of such an optical article, there is provided an antireflection layer formed directly on an optical substrate or having at least one other layer interposed between the antireflection layer and the optical substrate, and an antifouling layer formed directly on the antireflection layer. The anti-reflection layer comprises more than 2 sub-layers, wherein at least one of the sub-layers except the outermost layer of the anti-reflection layer is the layer comprising the part subjected to the nitriding treatment.

One embodiment of such an antireflection layer includes 2 or more low refractive index sublayers and at least one high refractive index sublayer sandwiched between the 2 or more low refractive index sublayers, and one of the 2 or more low refractive index sublayers is an outermost layer, and one of the other layers of the 2 or more low refractive index sublayers is the layer including the portion subjected to the nitriding treatment.

As another form of the optical article, there is an antireflection layer formed directly on an optical substrate or having at least one other layer interposed between the antireflection layer and the optical substrate. The antireflection layer includes 2 or more sublayers, and at least the outermost layer among the 2 or more sublayers is the layer including the nitrided portion.

Another aspect of the present invention is to provide a method of manufacturing an optical article having a functional layer formed directly on an optical substrate or sandwiching at least one other layer between the functional layer and the optical substrate and the functional layer including at least one sublayer.

The functional layer referred to herein means a thin film having a specific function, including an antireflection layer, an optical filter such as a low-pass filter, a high-pass filter, a band-pass filter, and the like, and a hard film and the like.

The method for manufacturing an optical article includes a step of forming a functional layer. The step of forming the functional layer includes a layer forming step of forming a sub-layer by vacuum deposition and a nitriding step of nitriding the surface including the sub-layer obtained in the layer forming step.

In the method for producing an optical article, it is preferable that the nitriding step includes (includes): a gas containing nitrogen is introduced into a vacuum chamber in which the layer forming step is performed, and plasma treatment or ion gun treatment is performed.

Drawings

FIG. 1 is a schematic view showing a schematic structure of an apparatus for forming an antireflection layer.

Fig. 2 is a flowchart illustrating a method for manufacturing a lens according to the first embodiment.

Fig. 3 is an enlarged cross-sectional view showing the general structure of the antireflection layer.

FIG. 4 is a schematic view showing the schematic structure of an apparatus for forming an antireflection layer and an antifouling layer.

Fig. 5 is a flowchart showing a method for manufacturing a lens according to a second embodiment.

Fig. 6 is an enlarged cross-sectional view showing the general structure of the antireflection layer and the antifouling layer.

FIG. 7 is a schematic view showing the schematic structure of an apparatus for forming a functional thin film and an antifouling layer.

Fig. 8 is a flowchart illustrating a method for manufacturing a lens according to a third embodiment.

Fig. 9 is an enlarged cross-sectional view showing a general structure of the functional film.

Description of the symbols

1 optical substrate (Plastic lens, 1a lens, 1b lens, 1c lens)

2 hard coating

3 anti-reflection layer (functional layer)

4 antifouling layer

10a, 10b and 10c optical article

30 (low refractive index) film, 31 to 34 sublayers, 35 uppermost layer (outermost layer, sublayer), 39 (nitride-containing) partial layer

40 workpiece substrate (base material)

50 film forming apparatus, 52, 53, and 54 vacuum generating apparatus (52a rotary pump, 52b roots pump, 52c cryopump; 53a rotary pump, 53b roots pump, 53c cryopump; 54a rotary pump, 54b roots pump, 54c turbo molecular pump), 55 AR vapor deposition source [55a AR vapor deposition source (low refractive index substance), 55b AR vapor deposition source (high refractive index substance) ], 56 electron gun, 57 shutter, 59a antifouling layer vapor deposition source, 59b antifouling layer vapor deposition source

60 plasma generator (RF coil), 61 matching box, 62 high frequency oscillator, 63 oxygen, 64a nitrogen, 64b argon, 65 automatic pressure regulator, 66 mass flow controller, 67 compensation plate, 68 heater, 69 mass flow controller

70 ion gun, 71 DC power supply, 72 RF power supply

80 strutting arrangement, 81 dome

Detailed Description

(first embodiment)

One mode of the first embodiment of the present invention relates to a method for manufacturing an optical article, the method including a step of forming an antireflection layer having a multilayer structure, the antireflection layer including at least one sub-layer composed of silicon dioxide, and the antireflection layer being formed directly on an optical substrate or sandwiching at least one other layer between the antireflection layer and the optical substrate. The step of forming the antireflection layer includes a layer formation step of forming at least one sublayer made of silicon dioxide by vacuum deposition and a nitriding step of nitriding the surface of the at least one sublayer made of silicon dioxide.

Here, the sub-layers described in the present application refer to layers constituting an anti-reflection layer or a functional layer of a multilayer structure. In particular, the sublayer is defined by SiO₂Or SiO_xIsosilica, or MgF₂Low refractive index sublayer of ZrO of₂、Ta₂O₅、TiO₂、CeO₂Or Y₂O₃Equal materialA high refractive index sublayer of material, and Al₂O₃Or CeF₃Etc. are formed by the intermediate refractive index sub-layers.

In the present method for manufacturing an optical article, a vacuum-evaporated sub-layer or sub-layers made of silicon dioxide are subjected to a nitriding treatment instead of using a silicon nitride layer as a single sub-layer in the multilayer structure. That is, the surface of the sub-layer composed of silicon dioxide is partially nitrided to obtain an effect that acts as silicon nitride.

In the nitriding step, a gas containing nitrogen is introduced into a vacuum chamber in which the layer forming step is performed, and plasma treatment or ion gun treatment is performed. The nitriding treatment in this manufacturing method is intended to nitride partially or entirely the surface of one sub-layer made of silicon dioxide, which is produced in the layer forming step. Therefore, the film thickness does not need to be strictly controlled. In addition, even if the timing of controlling the ion current is not precisely grasped, silicon nitride can be easily introduced into the antireflection layer of the multilayer structure. The scratch resistance of the anti-reflective layer can be improved by introducing silicon nitride. In particular, in plasma treatment, silicon nitride can be easily introduced into an apparatus for vacuum deposition or during deposition without using an ion source.

Other aspects of the first embodiment of the present invention relate to an optical article having an antireflection layer formed directly on an optical substrate or having at least one other layer sandwiched between the antireflection layer and the optical substrate. The antireflection layer has a multilayer structure including at least one sublayer composed of silicon dioxide, and a surface of the at least one sublayer composed of silicon dioxide on a side facing away from the optical substrate is subjected to nitriding treatment.

In addition, in another mode of the first embodiment of the present invention, at least one sublayer made of silicon dioxide in the antireflection layer of the optical article has a nitrogen-containing partial layer formed on a surface on the side facing away from the optical substrate. In this case, the partial layer in the present application refers to a surface layer portion of the sub-layer made of silicon dioxide. The invention relates to nitriding the surface layer portion of at least one sublayer of silicon dioxide. That is, at least one of the sub-layers made of silicon dioxide is a layer including a nitrided portion (surface nitrided layer).

By nitriding the sub-layer composed of silicon dioxide, a nitrogen-containing partial layer is formed on the side of at least one sub-layer composed of silicon dioxide facing away from the optical substrate. Therefore, since the scratch-susceptible surface of the anti-reflection layer is nitrided and silicided, the scratch resistance thereof can be improved.

Part of the layer containing Si_sO_tN_u(s and u are positive numbers, and t is a number of 0 or more). After the sub-layer made of silicon dioxide is nitrided, a region containing silicon nitride is partially or entirely formed on the surface of the sub-layer, and therefore the scratch resistance can be improved. In addition, there is a limit to the thickness and/or area of the partial layer formed by the nitriding process, and therefore, the partial layer can maintain the optical properties of silicon dioxide as a sub-layer, so that there is little need to modify the film design of the anti-reflection layer. In addition, the presence of silicon nitride improves scratch resistance and makes it possible to effectively utilize the characteristics of the sub-layer made of silicon dioxide, that is, to impart adhesion between the substrate and the upper layer.

In the optical article according to the first embodiment of the present invention, it is preferable that at least one of the sublayers made of silicon dioxide subjected to the nitriding treatment is a layer farthest from the optical substrate in the antireflection layer. In the optical article according to the first embodiment of the present invention, at least one of the nitrogen-containing partial layers is preferably an outermost layer of the antireflection layer. The nitrided at least one sub-layer of silicon dioxide, which may be any one of the layers in the multilayer structure, contributes to the improvement of the scratch resistance of the anti-reflective layer. Considering that the uppermost layer, i.e., the sub-layer forming the surface facing away from the optical substrate side, is most susceptible to scratches, it is preferable to subject the sub-layer to a nitriding process.

Fig. 1 is a schematic structural view of a film forming apparatus 50 for forming an antireflection layer 3 having a multilayer structure, the antireflection layer 3 being formed on the surface of a substrate (workpiece) 40 placed on a support device 80 by vacuum evaporation. The supporting device 80 has a disk-shaped dome 81 projecting upward, and a plurality of work substrates (optical substrates, specifically, lens substrates) 40 are concentrically arranged on the dome 81, and a film is formed on the work substrates 40 while rotating the dome 81. The film forming apparatus 50 has three chambers CH1, CH2, and CH3 through which the supporting apparatus 80 can pass. The chambers CH1 to CH3 can be sealed with each other, and the internal pressures of the chambers CH1 to CH3 are controlled by vacuum generators 52, 53, and 54, respectively.

The chamber CH1 is an inlet or a door chamber, and degassing is performed by keeping the inside of the chamber CH1 at a certain pressure for a certain time after the support device 80 is introduced from the outside. The chamber CH1 is provided with a vacuum generator 52, and the vacuum generator 52 has a rotary pump 52a, a roots pump 52b, and a cryopump 52 c.

The chamber CH2 is a second chamber in which an antireflection layer (AR layer) is formed. Therefore, the chamber CH2 includes AR vapor deposition sources 55a and 55b, an electron gun 56 for vapor deposition from the AR vapor deposition source 55, and an openable shutter 57 for adjusting the amount of vapor deposition. The antireflection layer has a structure in which a low-refractive-index sublayer containing silicon dioxide as a main component and a high-refractive-index sublayer composed of another composition having, for example, TiO are laminated₂、Nb₂O₃、Ta₂O₅、ZrO₂One or more than 2. Therefore, at least two vapor deposition sources 55a and 55b and an electron gun 56 for heating and melting the vapor deposition sources 55a and 55b are provided in the chamber CH 2. The chamber CH2 is kept at an appropriate pressure by the vacuum generator 53, and the vacuum generator 53 includes a rotary pump 53a, a roots pump 53b, and a cryopump 53 c.

In addition, a mass flow controller 66 for controlling the atmosphere in the chamber is connected to the chamber CH 2. The oxygen gas supply source 63 and the nitrogen gas supply source 64a are connected to a mass flow controller 66 so that the atmosphere in the chamber CH2 can be controlled to 100% oxygen gas or 100% nitrogen gas, or a mixture gas of oxygen gas and nitrogen gas in an appropriate ratio.

Further, an RF coil 60 for generating high-frequency plasma is provided inside the chamber CH 2. By connecting the RF coil 60 to the high-frequency oscillator 62 through the matching box 61, plasma having a predetermined output power is generated at a predetermined frequency in the chamber CH 2.

Further, an ion gun 70 is provided inside the chamber CH 2. The ion gun 70 is connected to a DC power supply 71 and an RF power supply 72, and can irradiate ions of a predetermined energy onto the workpiece substrate 40 placed on the support device 80. The ion gun 70 is connected to the oxygen gas supply source 63 and the nitrogen gas supply source 64a via the mass flow controller 69, so that the ion gun 70 can irradiate the workpiece substrate 40 with oxygen ions or nitrogen ions.

The chamber CH3 is a removal chamber. The support device 80 on which the workpiece substrate 40 having the antireflection layer on one side is placed is moved from the chamber CH2 to the chamber CH3, and then the workpiece substrate 40 is turned over and returned to the chamber CH2 again. Next, after forming the antireflection layer on the other surface of the workpiece substrate 40, the support device 80 is returned to the chamber CH3, and then the pressure in the chamber CH3 is returned to atmospheric pressure, and the support device 80 is taken out. The chamber CH3 is maintained at an appropriate pressure by a vacuum generator 54 having a rotary pump 54a, a roots pump 54b, and a turbo-molecular pump 54 c. The workpiece substrate 40 taken out of the chamber CH3 together with the supporting device 80 is placed in a constant temperature and humidity chamber (not shown) and annealed in an atmosphere of appropriate humidity and temperature. The workpiece substrate 40 is left in the chamber for a predetermined time to be aged.

The film formation apparatus 50 can perform the nitridation process on the low refractive index sublayer mainly composed of silicon dioxide by using the plasma generation apparatus (RF coil) 60 or the ion gun 70 provided in the chamber CH 2. The atmosphere in the chamber CH2 is adjusted to a nitrogen atmosphere or a mixed atmosphere of nitrogen and oxygen by using the automatic pressure adjuster 65, and then, a plasma is generated by the RF coil 60, thereby irradiating nitrogen ions to the silicon dioxide sublayer, and nitriding the sublayer. The atmosphere in chamber CH2 may also be nitrogen-argon or nitrogen-oxygen-argon. Further, the surface of the sub-layer made of silicon dioxide can be nitrided by irradiating the workpiece substrate 40 with nitrogen ions using the ion gun 70.

It is very difficult to form a sub-layer made of silicon nitride by vacuum evaporation. However, it is relatively easy to form nitride on the surface by performing plasma treatment or ion gun treatment on silicon oxide. In this case, Si is formed on the surface₃N₄Compounds other than nitrogen and silicon, e.g. Si_sO_tN_u(s and u are positive integers, and t is an integer of 0 or more) and SiO₂A mixture of (a). That is, the nitride-containing partial layer is formed in a state of entirely or partially covering the surface of the sub-layer composed of silicon dioxide, and therefore the durability of the covered portion is improved. In addition, since the nitride-containing partial layer is formed only on the outermost layer of the sub-layer composed of silicon dioxide, there is little influence on the film design of the antireflection layer.

Fig. 2 is a flowchart illustrating a process of forming an antireflection layer having a multilayer structure on a work substrate 40 in a film formation apparatus 50. Fig. 3 is a cross-sectional view of the film structure (layer structure) of the optical article 10a of the present embodiment including the antireflection layer 3.

The antireflection layer 3 includes, as an example, a 1 st sublayer 31 made of silicon oxide, a 2 nd sublayer 32 made of zirconium oxide, a 3 rd sublayer 33 made of silicon oxide, a 4 th sublayer 34 made of zirconium oxide, and a 5 th sublayer 35 made of silicon oxide, which are formed on the substrate 1.

When the optical substrate (base material) 1 is plastic, the hard coat layer 2 is formed on the optical substrate 1 before the antireflection layer 3 is formed in step 11. In order to improve the adhesion between the hard coat layer 2 and the substrate 1, a primer layer may be formed between the hard coat layer 2 and the substrate 1. The hard coat layer 2 imparts scratch resistance to the plastic lens 1. Meanwhile, the hard coating layer 2 exists between the plastic lens 1 and the anti-reflection layer 3, so that the anti-reflection layer 3 has good adhesion with the plastic lens 1, and has a function of preventing the anti-reflection layer 3 from being stripped from the plastic lens 1. Therefore, even if the anti-reflection layer 3 has not high adhesion to the plastic lens 1, the adhesion between the plastic lens 1 and the anti-reflection layer 3 can be improved by the hard coat layer 2.

As a method of forming the hard coat layer 2, the following method is generally employed: a curable composition capable of forming a hard coat layer 2 is applied to the surface of a plastic lens 1, and the coating film is cured. When the plastic lens 1 is a thermoplastic resin, it is preferable to cure the coating film by using an electromagnetic wave such as ultraviolet rays or an ionizing radiation such as an electron beam, rather than curing the coating film by heat curing.

For example, a thermosetting composition containing inorganic fine particles. The composition comprises a silicone compound which generates a silanol group by ultraviolet irradiation and a photocurable silicone composition mainly comprising an organopolysiloxane having a reactive group such as a halogen atom or an amino group which undergoes a condensation reaction with the silanol group. The curable composition containing inorganic fine particles further contains an acrylic ultraviolet-curable monomer composition such as UK-6074 manufactured by Mitsubishi Rayon Co., Ltd., and SiO₂Or TiO₂Inorganic fine particles having an equivalent particle diameter of 1nm to 100 nm. The curable composition containing inorganic fine particles is obtained by dispersing a photocurable silicon composition, an acrylic ultraviolet-curable monomer composition, and inorganic fine particles in a silane compound or a silane coupling agent having a polymerizable group such as a vinyl group, an allyl group, an acryloxy group, or a methacryloxy group, and a hydrolyzable group such as a methoxy group.

As a method for forming the coating film of the hard coat layer 2, a dipping method, a spin coating method, a spray coating method, a flow coating (flow) method, a doctor blade method, or the like can be used. In order to improve the adhesion, the surface of the plastic lens 1 is preferably subjected to a surface treatment using corona discharge, high-voltage discharge such as microwave, or the like, before the coating film is formed. The formed coating film is cured by heating, ultraviolet rays or electron beams, etc., to obtain the hard coat layer 2.

The substrate 1 on which the hard coat layer 2 is formed is fixed on a support device 80 as a work substrate 40, and is conveyed to the film forming apparatus 50. In the film forming apparatus 50, the supporting apparatus 80 is first introduced into the chamber CH1 and degassed, and then the supporting apparatus 80 is moved into the chamber CH2 and the plasma processing in step 12 is performed. In step 13, the 1 st sublayer 31 made of silicon oxide is formed (layer forming step), and then, in step 14, the surface of the sublayer 31 is nitrided by plasma treatment or ion gun treatment (nitriding treatment step). In this way, the partial layer 39 containing a nitride is formed on the surface (surface facing away from the substrate 1) of the seed layer 31 made of silicon oxide so as to cover the entire surface or a part of the surface. In this case, a gas having an arbitrary composition and containing nitrogen gas may be used as the introduced gas, and examples thereof include 100% nitrogen gas, a mixed gas of nitrogen gas and oxygen gas, a mixed gas of nitrogen gas and argon gas, or a mixed gas of nitrogen gas, oxygen gas and argon gas.

After the 2 nd sub-layer 32 made of zirconia is formed in step 15, the 3 rd sub-layer 33 made of silica is formed in step 16. Then, in step 17, the surface is nitrided in the same manner as in step 14. In steps 15 and 16, a 2 nd sub-layer 32 of high refractive index and a 3 rd sub-layer 33 of low refractive index are formed successively. Thereafter, the surface of the low refractive index 3 rd sub-layer 33 formed later can be nitrided by the nitriding process of step 17. That is, by continuously performing the layer forming step of step 16 and the nitriding step of step 17, the surface of the seed layer formed in the layer forming step can be nitrided. If step 15 and step 16 are combined into one layer forming step, the surface of the seed layer formed before the nitriding treatment may be nitrided in step 17.

After the formation of the 4 th sublayer 34 composed of zirconia in step 18, the 5 th sublayer 35 composed of silica is formed in step 19. In step 20, the surface is nitrided in the same manner as in step 14. Thus, the antireflection layer 3 having a 5-layer structure is formed on one side of the optical article, so that, at step 21, the substrate 40 is turned over and fixed on the supporting device 80, and steps 12 to 20 are repeated to form the antireflection layer 3 having a multilayer structure. When the antireflection layers 3 are formed on both sides of the substrate 40, the substrate 1 (the work substrate 40) is taken out at step 22.

Here, the three silicon oxide sublayers 31, 33, and 35 are shared, and only the uppermost sublayer 35 among them may be subjected to the nitriding treatment, or any two layers including the uppermost sublayer 35 may be subjected to the nitriding treatment. In the above-described nitriding treatment, only the extremely thin surface of the silicon oxide sublayer is nitrided, and therefore, the performance as the antireflection layer 3 is hardly affected.

(examples 1 to 1)

Several examples of manufacturing plastic spectacle lenses as optical articles according to the manufacturing method shown in fig. 2 will be described below. In the following examples and comparative examples, a plastic lens substrate for spectacles (manufactured by Seiko Epson Co., Ltd., trade name: Seiko super Sovereign) was used as the optical substrate 1. In step 11, hard coat layers 2 are formed on both sides of the optical substrate 1. In the subsequent steps, the optical base 1 on which the hard coat layer 2 is formed is used as a work substrate 40, and the antireflection layer 3 is formed thereon.

The work substrate 40 is fixed to the dome 81 of the supporting device 80 with the concave surface facing downward, and then conveyed to the film forming apparatus 50. In step 12, after degassing in the chamber CH1, 100% argon gas was introduced into the chamber CH2, and the gas pressure was controlled to 4.0X 10^-2Pa while processing the workpiece substrate 40 with the plasma generated by the high-frequency plasma generating device. Plasma treatment was performed for 1 minute under the condition of plasma generation at a frequency of 13.56MHz and a power of 400W. The purpose of this treatment is to clean the substrate surface, thereby improving the adhesion between the substrate 1 and the antireflection layer 3.

Then, performing steps 13-20, alternately performing SiO₂Sublayers 31, 33 and 35 and ZrO₂Evaporation of the sublayers 32 and 34, the antireflection layer 3 constituted by these sublayers is formed. The film thickness of each layer was adjusted so that the 1 st Sublayer (SiO)₂) The film thickness of 31 is 0.09 lambda and the 2 nd sublayer (ZrO)₂)32 film thickness of 0.16 lambda, 3 rd Sublayer (SiO)₂)33 film thickness of 0.05 lambda, 4 th sublayer (ZrO)₂)34 film thickness of 0.27 lambda, 5 th Sublayer (SiO)₂) The film thickness of 35 was 0.27. lambda..

The uppermost layer 35 of the anti-reflection layer 3 is SiO₂And (3) a layer. The plasma generating apparatus 60 is used in the nitridation processing of steps 14, 17, and 20. Therefore, in the deposition of SiO₂After layering, nitrogen and oxygen were mixed at 7: 3 is introduced into the chamber at a controlled gas pressure of 4.0X 10^-2Pa, and a high-frequency plasma generator is used to generate plasma. Plasma treatment was performed for 5 minutes under the condition that plasma was generated at a frequency of 13.56MHz and a power of 600W. Thus, the SiO in the 1 st 31, 3 rd 33 and 5 th 35 sub-layers₂A nitride-containing partial layer 39 is formed on the layer surface. That is, the 1 st, 3 rd, and 5 th sub-layers 31, 33, and 35 are layers including portions subjected to nitriding treatment (surface-layer nitriding treatment layers).

Then, in step 21, the support device 80 is moved into the chamber CH3, the support device 80 is removed from the chamber, the convex surface of the lens is fixed downward on the dome 81 of the support device 80 by turning it over, and the same process as described above is performed. Then, in step 22, the workpiece substrate 40 is taken out of the chamber CH 3. Thus, a plastic lens having antireflection layers 3 on both sides of the workpiece substrate 40 (lens base material 1) was manufactured (sample S1-1). I.e. on the opposite side of the substrate 1 with the hard coating 2 also with the anti-reflection layer 3. In sample S1-1, the surfaces of the silicon dioxide sublayers 31, 33, and 35 of the antireflection layer 3 were nitrided, that is, the surface facing away from the substrate 1 was nitrided.

(examples 1 and 2)

In example 1-2, steps 14 and 17 were not performed, and a plastic lens having an antireflection layer 3 having a 5-layer structure was produced in the same manner as in example 1-1 (sample S1-2). Therefore, in sample S1-2 of this example 1-2, of the silicon dioxide sublayers 31, 33, and 35 included in the antireflection layer 3, only the outermost (5 th layer) sublayer 35 (i.e., the sublayer 35 of the antireflection layer 3 formed on the side facing away from the optical substrate 1) was subjected to nitriding treatment to form the nitride-containing partial layer 39.

(examples 1 to 3)

In example 1-3, step 14 was not performed, and a plastic lens having an antireflection layer 3 having a 5-layer structure was produced in the same manner as in example 1-1 (sample S1-3). Therefore, in sample S1-3 of this example 1-3, of the silicon dioxide sub-layers 31, 33, and 35 included in the antireflection layer 3, only the 3 rd sub-layer 33 and the 5 th sub-layer 35 were subjected to nitriding treatment, and the nitride-containing partial layer 39 was formed.

(examples 1 to 4)

In examples 1 to 4, step 17 was not performed, and a plastic lens having an antireflection layer 3 having a 5-layer structure was produced in the same manner as in example 1 to 1 (sample S1-4). Therefore, in sample S1-4 of this example 1-4, of the silicon dioxide sub-layers 31, 33, and 35 included in the antireflection layer 3, only the 1 st sub-layer 31 and the 5 th sub-layer 35 were subjected to nitriding treatment, and the nitride-containing partial layer 39 was formed.

(examples 1 to 5)

In examples 1 to 5, steps 12 to 20 were performed to perform nitridation treatment on all the silicon dioxide sublayers 31, 33 and 35 included in the antireflection layer 3. However, in the nitriding process of steps 14, 17 and 20, the ion gun 70 is used instead of the plasma generating device 60. Therefore, nitrogen gas 64a and oxygen gas 63 were introduced into the ion gun 70 at a ratio of 7: 3, the flow rate was controlled at 35SCCM, and the sublayers 31, 33 and 35 were irradiated with ions. The pressure in the chamber during the control process was 4X 10^-3Ion irradiation was carried out for 5 minutes under conditions of ion irradiation at a frequency of 13.56MHz, an RF power of 450W, an accelerating voltage of 500V and a suppression voltage of 300V at Pa. The rest was the same as in example 1-1.

Therefore, in sample S1-5 of this example 1-5, all of the silicon dioxide sublayers 31, 33, and 35 included in the antireflection layer 3 are subjected to nitriding treatment to form the nitride-containing partial layer 39.

(examples 1 to 6)

In examples 1 to 6, lenses having an antireflection layer 3 composed of a 7-layer structure were manufactured. Therefore, a process of depositing a 6 th sub-layer, a process of depositing silicon dioxide as a 7 th sub-layer of an outermost layer, and a process of nitriding the silicon dioxide of the outermost layer are added. In addition, TiO is used in forming the high refractive index sub-layer₂To replace ZrO₂. The rest was the same as in example 1-1.

In the step of forming the high refractive index sub-layer, ion accelerator evaporation (ion assisted deposition) is used to perform TiO deposition₂And (4) evaporation. In the ion irradiation conditions, 100% oxygen gas with a flow rate of 35SCCM was introduced into the ion gun 70, and the frequency was adjusted to 13.56MHz, the RF power was adjusted to 450W, the acceleration voltage was adjusted to 500V, and the suppression voltage was adjusted to 300V. The pressure in the chamber during the treatment was 4X 10^-3Pa. In this case, sublayer 1 (SiO)₂) Has a film thickness of 0.08 lambda and a 2 nd sublayer (TiO)₂) The film thickness of (2) is 0.07 lambda, the 3 rd Sublayer (SiO)₂) Has a film thickness of 0.10 lambda and a 4 th sublayer (TiO)₂) The film thickness of (2) is 0.18 lambda, 5 th Sublayer (SiO)₂) Has a film thickness of 0.07 lambda of sub-layer No. 6 (TiO)₂) The film thickness of (2) is 0.14 lambda, 7 th Sublayer (SiO)₂) The film thickness of (2) was 0.26. lambda.

Therefore, in sample S1-6 of this example 1-6, all of the silicon dioxide sub-layers included in the antireflection layer 3 were subjected to nitriding treatment to form the nitride-containing partial layer 39.

Comparative examples 1 to 1

In comparative example 1-1, steps 14, 17 and 20 were not performed, and a plastic lens having the same composition as in example 1-1 and not subjected to nitriding treatment (sample SR 1-1), i.e., having SiO with a low refractive index was produced (sample SR 1-1)₂Sub-layer and high-refractive-index ZrO₂And 5-layer structured anti-reflection layers 3 formed by sub-layers. The rest was the same as in example 1-1. Therefore, in sample SR 1-1 of this comparative example 1-1, all of the silicon dioxide sublayers 31, 33, and 35 included in the antireflection layer 3 were not nitridedAnd (6) processing.

Comparative examples 1 and 2

In comparative examples 1-2, plastic lenses having the same composition as in examples 1-6 and not subjected to nitriding treatment (sample SR 1-2) were produced, i.e., the plastic lenses had SiO with a low refractive index₂Sublayer and high refractive index TiO₂And 7-layer structured anti-reflection layers 3 formed by sub-layers. The other points are the same as in examples 1 to 6. Therefore, in the sample SR 1-2 of this comparative example 1-2, the nitridation treatment was not performed on all the silicon dioxide sublayers included in the antireflection layer 3.

(evaluation)

The scratch resistance of samples S1-1 to S1-6, SR 1-1 and SR 1-2 produced in examples 1-1 to 1-6 and comparative examples 1-1 and 1-2 was evaluated by the following method. The evaluation results are shown in Table 1. The steel wool (#0000) wound around the jig was reciprocated 50 times on the outermost surface of the antireflection layer 3 of each of samples S1-1 to S1-6, SR 1-1 and SR 1-2 in a state of a load of 2 kg. The degree of scratching thus produced was compared with the standard sample and evaluated on four scales of A, B, C and D. Where a indicates the best, B, C, D indicates the degradation sequentially.

TABLE 1

In samples S1-1 to S1-6 of examples 1-1 to 1-6, at least one of the silicon dioxide sublayers was nitrided. The samples S1-1 to S1-6 were evaluated as good in the scratch resistance test (A). On the other hand, the samples SR 1-1 and SR 1-2 of comparative examples 1-1 and 1-2, which were not nitrided, were evaluated as poor (D) in the scratch resistance test.

When the results were comprehensively evaluated, all of the samples S1-1 to S1-6 of the examples were very good (excellent) as products. Samples SR 1-1 to SR 1-2 of the comparative example were all X (failed). As a result, it was found that the scratch resistance was improved by nitriding at least one of the silicon dioxide sublayers.

Although not clearly shown in table 1 (evaluation results), the samples of examples 1-2, 1-3 and 1-4 in which only the uppermost layer and any two layers including the uppermost layer were nitrided had slightly inferior scratch resistance, although the level of scratch resistance was also good (a), compared to the samples of examples 1-1, 1-5 and 1-6 in which all the silica sub-layers were nitrided. However, the differences are within the full allowable range.

In addition, the first embodiment (example) described above relates to an optical article having an antireflection layer formed on a plastic eyeglass lens having a hard coat layer. For an optical article having a glass substrate, an antireflection layer may be formed on the substrate without a hard coat layer interposed between the substrate and the antireflection layer, and for such an optical article having a glass substrate, the manufacturing method disclosed in the above embodiment may also be applied. The optical article is not limited to a spectacle lens, but includes optical products such as an optical element of an image display device, a prism, an optical fiber, an element for an information recording medium, and an optical filter, and the manufacturing method disclosed in the above embodiment can be applied to these optical articles.

(second embodiment)

A layer (antifouling layer) having an antifouling function such as water repellency is often formed on an optical article used in daily life such as an eyeglass lens. One of the purposes of the antifouling layer is to prevent the surface from being contaminated with grease or the like, thereby suppressing the deterioration of optical performance. The most suitable composition for forming the antifouling layer is a fluorine-containing silane compound. The antifouling layer formed from the fluorine-containing silane compound has high water repellency and high antifouling property. Further, when silicon oxide is used as the uppermost layer of the anti-reflection layer, the anti-fouling layer formed of a fluorine-containing silane compound has advantages of high adhesion to the surface of the anti-reflection layer and high durability. This is probably due to the formation of siloxane bonds between the anti-reflection layer and the stain-proofing layer by oxygen atoms on the surface of the anti-reflection layer.

On the other hand, if the silicon nitride layer is used as the uppermost layer of the anti-reflection layer instead of the silicon oxide layer, siloxane bonds are difficult to form, and the durability of the antifouling layer is likely to be lowered. Therefore, if the silicon nitride layer is present in the uppermost layer of the anti-reflection layer, a reaction between the uppermost layer of the anti-reflection layer and the anti-fouling layer formed on the silicon nitride layer is inhibited, and there is a problem that the durability of the anti-fouling layer is lowered.

One mode of the second embodiment of the present invention relates to a method for manufacturing an optical article, the method including a step of forming an antireflection layer and an antifouling layer, the antireflection layer being formed directly on an optical substrate or sandwiching at least one other layer between the antireflection layer and the substrate, and the antireflection layer having a multilayer structure including 2 or more low-refractive-index sublayers and at least one high-refractive-index sublayer. The step of forming the anti-reflection layer and the anti-fouling layer includes the steps of: the method comprises a 1 st step of forming a 1 st low refractive index sublayer, a nitriding step of nitriding the surface of the 1 st low refractive index sublayer, a 2 nd step of forming a 2 nd low refractive index sublayer on the surface of the 1 st low refractive index sublayer facing away from the optical substrate with at least one high refractive index sublayer sandwiched therebetween, and a step of directly forming an antifouling layer on the surface of the 2 nd low refractive index sublayer facing away from the optical substrate.

The sublayers described here are the same as those described in the first embodiment. In the method for manufacturing the optical article, the low refractive index sub-layer made of silicon dioxide or the like is subjected to nitriding treatment instead of using silicon nitride as a single sub-layer of the multilayer structure. That is, the surface of the low refractive index sublayer is partially nitrided, thereby obtaining an effect of improving the film strength. In this production method, since the advantage of nitriding can be obtained while maintaining the layer structure of the anti-reflection layer having silicon dioxide as the low refractive index sublayer, for example, the 2 nd low refractive index sublayer having the anti-fouling layer laminated thereon can be selected without nitriding.

Therefore, in the 1 st step and the 2 nd step, the 1 st low refractive index sublayer and the 2 nd low refractive index sublayer are preferably formed of silicon dioxide.

In this manufacturing method, the 1 st low refractive index sublayer is formed by vacuum deposition in the 1 st step, and the surface of the low refractive index sublayer formed of silicon dioxide or the like can be partially or entirely nitrided by introducing a nitrogen-containing gas into the vacuum chamber in which the 1 st step is performed and performing plasma treatment or ion gun treatment on the gas in the nitriding treatment step. Therefore, it is not necessary to strictly control the film thickness for introducing the nitrided layer, and even if the ion current is not controlled or the time is accurately grasped, the nitrided film can be easily introduced into the anti-reflection layer having a multilayer structure, and the scratch resistance of the anti-reflection layer can be improved. In particular, in plasma processing, silicon nitride can be easily introduced into an apparatus for vacuum evaporation or during evaporation without the need for an ion source.

Other aspects of the second embodiment of the present invention relate to an optical article having an antireflection layer formed directly on an optical substrate or having at least one other layer sandwiched between the optical substrate and the antireflection layer, and an antifouling layer. The anti-reflection layer comprises a 1 st low-refractive-index sublayer and a 2 nd low-refractive-index sublayer, wherein the surface, facing away from the optical substrate, of the 1 st low-refractive-index sublayer is subjected to nitriding treatment, the 2 nd low-refractive-index sublayer is formed on the surface, facing away from the optical substrate, of the 1 st low-refractive-index sublayer, at least one high-refractive-index sublayer is sandwiched between the 1 st low-refractive-index sublayer and the 2 nd low-refractive-index sublayer, and then the anti-fouling layer is directly laminated on the surface, facing away from.

In addition, an optical article in another mode of the second embodiment of the present invention has an antireflection layer formed directly on an optical substrate or having at least one other layer interposed between the optical substrate and the antireflection layer, and an antifouling layer. The anti-reflection layer comprises a 1 st low-refractive-index sublayer and a 2 nd low-refractive-index sublayer, wherein the 1 st low-refractive-index sublayer is provided with a nitrogen-containing part layer on the side opposite to the optical substrate, the 2 nd low-refractive-index sublayer is formed on the surface, opposite to the optical substrate, of the 1 st low-refractive-index sublayer, at least one high-refractive-index sublayer is sandwiched between the 1 st low-refractive-index sublayer and the 2 nd low-refractive-index sublayer, and then the anti-fouling layer is directly laminated on the surface, opposite to the. The partial layers are the same as those described in the first embodiment.

That is, the optical article has an antireflection layer formed directly on an optical substrate or at least one other layer sandwiched between the optical substrate and the antireflection layer, and the antireflection layer includes 2 or more sublayers, and among the 2 or more sublayers, at least one layer whose surface layer is nitrided except for the outermost layer of the antireflection layer, that is, the surface layer nitrided layer is SiO_xA layer which is the main component and is a layer containing a nitrided portion of the surface of the layer facing away from the optical substrate. One form of the antireflection layer includes 2 or more low refractive index sublayers, one of the 2 or more low refractive index sublayers is an outermost layer, at least one of the other 2 or more low refractive index sublayers is a layer whose surface layer is subjected to nitriding treatment, the outermost low refractive index sublayer is formed on a surface of the other low refractive index sublayers, which surface faces away from the optical substrate, and at least one high refractive index sublayer is interposed between the other low refractive index sublayers and the outermost low refractive index sublayer.

By nitriding the 1 st low refractive index sublayer, at least one of the sublayers forms a nitrogen-containing partial layer on the side opposite to the optical substrate, and the scratch-susceptible surface is nitrided, so that the scratch resistance of the surface can be improved. Further, since the 2 nd low refractive index sublayer on which the antifouling layer is laminated is not nitrided, adhesion between the 2 nd low refractive index sublayer and the antifouling layer can be maintained, and durability of the antifouling layer can be improved.

Preferably the 1 st and 2 nd low refractive index sublayers are formed of silicon dioxide. In this case, the partial layer contains Si_sO_tN_u(s and u are positive integers, and t is an integer of 0 or more). When the sub-layer formed of silicon oxide is nitrided, a region containing silicon nitride is partially or entirely formed on the surface of the sub-layer, whereby the scratch resistance can be improved. In addition, since the thickness and/or area of the partial layer formed by the nitridation process is limited, the optical properties of silicon dioxide as a sub-layer are preserved. Therefore, little or no modification of the film design of the antireflective layer is required. In addition, silicon nitride can improve scratch resistance and can effectively utilize the characteristics of a sub-layer formed of silicon dioxide, that is, can impart adhesion between a substrate and an upper layer. Further, since the uppermost silicon oxide layer on which the antifouling layer is laminated is not nitrided, the durability of the antifouling layer can be maintained and the scratch resistance can be improved.

A suitable composition for forming the antifouling layer is a fluorosilane-containing compound. An example of the fluorine-containing silane compound suitable for the antifouling layer is a compound represented by the following general formula (1).

Compound 1

In the general formula (1), Rf¹Represents a perfluoroalkyl group, X represents a hydrogen atom, a bromine atom or an iodine atom, Y represents a hydrogen atom or a lower alkyl group, Z represents a fluorine atom or a trifluoromethyl group, R¹Represents a hydroxyl group or a hydrolyzable group, R²Represents a hydrogen atom or a monovalent hydrocarbon group. a. b, c, d and e are integers of 0 or 1 or more, a + b + c + d + e is at least 1 or more, and the order of the repeating units in the formula, which are composed of a, b, c, d and e, is not limited. f represents 0, 1 or 2, g represents 1, 2 or 3, and h represents an integer of 1 or more.

Another example of the fluorine-containing silane compound suitable for the antifouling layer is a compound represented by the following general formula (2).

Compound 2

In the general formula (2), Rf²Comprises the formula: - (C)_kF_2k) O- (wherein k is an integer of 1 to 6) and represents a divalent group having an unbranched linear perfluoropolyalkyl ether structure. R³Represents a monovalent hydrocarbon group having 1 to 8 carbon atoms, and X represents a hydrolyzable group or a halogen atom. P represents 0, 1 or 2, n represents an integer of 1 to 5, and m and r represent 2 or 3.

Fig. 4 is a schematic structural view showing a film forming apparatus 50 for forming an antireflection layer of a multilayer structure on the surface of a substrate (workpiece) 40 placed on a supporting device 80 by vacuum evaporation.

The film forming apparatus 50 shown in fig. 4 is different from the film forming apparatus 50 shown in fig. 1 in the function of the chamber CH 3. In the film forming apparatus 50 shown in fig. 4, the chamber CH3 has a function as an outlet chamber, and a function of forming an antifouling layer by vapor deposition of a fluorine-containing silane compound in the chamber. Therefore, an antifouling layer vapor deposition source 59a impregnated with a fluorine-containing silane compound, a heater (halogen lamp) 68, and a compensation plate 67 for controlling the amount of discharge of the fluorine-containing silane compound by adjusting the opening degree are provided in the chamber CH 3. The chamber CH3 is maintained at an appropriate pressure by a vacuum generating device 54 equipped with a rotary pump 54a, roots pump 54b, and turbo-molecular pump 54 c. The workpiece substrate 40 taken out of the chamber CH3 together with the supporting device 80 is placed in a constant temperature and humidity bath (not shown), and the workpiece substrate 40 is annealed in an atmosphere of appropriate humidity and temperature. The workpiece substrate 40 is left in the chamber for a predetermined time to be aged. Other structures and actions are the same as those of the film forming apparatus 50 of the first embodiment, and therefore, the same reference numerals are used in the drawings, and a repetitive description thereof will be omitted.

Fig. 5 is a flowchart showing a process of forming an antireflection layer having a multilayer structure on the work substrate 40 in the film formation apparatus 50. Fig. 6 is a cross-sectional view showing the film structure of the optical article 10b of the present embodiment including the antireflection layer 3 and the stain-proofing layer 4. The antireflection layer 3 includes, as an example, a 1 st sublayer 31 made of silicon oxide, a 2 nd sublayer 32 made of zirconium oxide, a 3 rd sublayer 33 made of silicon oxide, a 4 th sublayer 34 made of zirconium oxide, and a 5 th sublayer 35 made of silicon oxide, which are formed on a substrate.

When the optical substrate (base material) 1 is plastic, in step 101, the hard coat layer 2 is formed on the optical substrate 1 before the antireflection layer 3 is formed, as in the manufacturing method shown in fig. 2.

The substrate 1 on which the hard coat layer 2 is formed is fixed to a supporting device 80 as a work substrate 40 and conveyed to a film forming apparatus 50. In the film forming apparatus 50, the supporting apparatus 80 is first introduced into the chamber CH1 and degassed, and then the supporting apparatus 80 is moved into the chamber CH2 and plasma processing is performed in step 102. In step 103, a 1 st sublayer 31 made of silicon oxide is formed (layer forming step (1 st step)), and then, in step 104, the surface of the sublayer 31 is nitrided by plasma treatment or ion gun treatment (nitriding treatment step). In this way, the partial layer 39 containing a nitride is formed on the surface (surface facing away from the substrate 1) of the seed layer 31 made of silicon oxide so as to cover the entire surface or a part of the surface. In this case, a gas having an arbitrary composition and containing nitrogen gas may be used as the introduced gas, and examples thereof include 100% nitrogen gas, a mixed gas of nitrogen gas and oxygen gas, a mixed gas of nitrogen gas and argon gas, or a mixed gas of nitrogen gas, oxygen gas and argon gas.

After the formation of the 2 nd sublayer 32 made of zirconia in step 105, the 3 rd sublayer 33 made of silicon oxide is formed in step 106 (layer formation step (1 st step)), and then surface nitridation (nitridation treatment step) is performed in step 107 in the same manner as in step 104.

After forming the 4 th sublayer 34 made of zirconia in step 108, the 5 th sublayer 35 made of silica is formed in step 109 (layer forming step (2 nd step)). The 5 th sublayer 35 is the uppermost layer of the antireflective layer 3. Therefore, after the layer forming step (the 2 nd step), in step 110, the support device 80 is moved to the chamber CH3, and the antifouling layer 4 made of a fluorine-containing silane compound is directly formed on the 5 th sublayer 35 made of silicon oxide. Thus, the antireflection layer 3 and the stain-proofing layer 4 having a 5-layer structure were formed on one surface of the optical article. In step 111, the substrate 40 is flipped over and fixed on the supporting device 80, and steps 102-110 are repeated. When the anti-reflection layer 3 and the stain-proofing layer 4 are formed on both sides of the substrate 40, the substrate 40 is taken out at step 112.

Here, 3 silicon oxide sublayers 31, 33, and 35 are common, and in addition to the uppermost sublayer 35, the low refractive index sublayers 31 and 33 may be nitrided. When the uppermost sublayer 35 is the 2 nd low refractive index sublayer, it is not nitrided. In addition, in the above-described nitriding treatment, only the extremely thin surface of the silicon oxide sub-layer is nitrided, and therefore, the performance as the antireflection layer 3 is hardly affected.

(example 2-1)

Several examples of manufacturing plastic spectacle lenses as optical articles according to the manufacturing method shown in fig. 5 will be described below. In the following examples and comparative examples, a plastic lens substrate for spectacles (manufactured by Seiko Epson Co., Ltd., trade name: Seiko super Sovereign) was used as the optical substrate 1. In step 101, hard coat layers 2 are formed on both sides of the optical substrate 1. The optical substrate 1 having the hard coat layer 2 formed thereon is used as a work substrate 40, and an antireflection layer 3 is formed thereon.

The work substrate 40 is fixed to the dome 81 of the supporting device 80 with the concave surface facing downward, and then conveyed to the film forming apparatus 50. In step 102, after degassing in the chamber CH1, 100% argon gas was introduced into the chamber CH2, and the gas pressure was controlled to 4.0 × 10^-2Pa while processing the workpiece substrate 40 by the plasma generated by the high-frequency plasma generating device. Plasma treatment was performed for 1 minute under the condition of plasma generation at a frequency of 13.56MHz and a power of 400W. The purpose of this treatment is to clean the substrate surface, thereby improving the adhesion between the substrate 1 and the antireflection layer 3.

Then, step 103-110 is performed to alternately perform SiO₂Sublayers 31, 33 and 35 and ZrO₂Evaporation of the sublayers 32 and 34, the antireflection layer 3 constituted by these sublayers is formed. The film thickness of each layer was adjusted so that the 1 st Sublayer (SiO)₂) The film thickness of 31 is 0.09 lambda and the 2 nd sublayer (ZrO)₂)32 film thickness of 0.16 lambda, 3 rd Sublayer (SiO)₂)33 film thickness of 0.05 lambda, 4 th sublayer (ZrO)₂)34 film thickness of 0.27 lambda, 5 th Sublayer (SiO)₂) The film thickness of 35 was 0.27. lambda..

The uppermost layer 35 of the anti-reflection layer 3 is SiO₂And (3) a layer. Plasma generating device 60 is used in the nitridation processes of steps 104 and 107. Therefore, in the deposition of SiO₂After layering, nitrogen and oxygen were introduced into the chamber CH2 in a ratio of 7: 3 under a controlled gas pressure of 4.0X 10^-2Pa, and generating plasma by using a high-frequency plasma generating device. Plasma treatment was performed for 5 minutes under the condition that plasma was generated at a frequency of 13.56MHz and a power of 600W. Thus, the SiO in the 1 st 31 and 3 rd 33 sub-layers₂A nitride-containing partial layer 39 is formed on the layer surface. That is, the 1 st sublayer 31 and the 3 rd sublayer 33 are sublayers (surface layer nitrided layers) including nitrided portions.

Then, the supporting device 80 is moved into the chamber CH3, and the antifouling layer 4 is formed (step 110). As the vapor deposition source 59a, a fluorine-containing organosilicon compound (product name: KY-130, which is a compound represented by the general formula (2)) produced by Shin-Etsu Chemical co. KY-130 was diluted with a fluorine-based solvent (product name: Novec HFE-7200, manufactured by Sumitomo 3M, Ltd.) to prepare a solution having a solid content of 3%, 1g of the solution was immersed in porous ceramic particles (pellet) and the particles were dried, and the dried particles were fixed in a chamber CH3 as a vapor deposition source 59 a. In the film formation process, a halogen lamp is used as the heater 68, and the particles as the evaporation source 59a are heated to 600 ℃ to evaporate the fluorine-containing organosilicon compound. The deposition time was 3 minutes.

After the antifouling layer 4 is formed, the supporting device 80 is taken out from the chamber, and the convex surface of the lens is fixed downward to the dome 81 of the supporting device 80 by inverting, and the same treatment as described above is performed. Thus, a plastic lens having the antireflection layer 3 and the antifouling layer 4 on both sides of the workpiece substrate 40 (lens base material 1) was manufactured (sample S2-1), i.e., having the antireflection layer 3 and the antifouling layer 4 also on the other side of the base material 1 on which the hard coat layer 2 was formed. In sample S2-1, the silicon dioxide sublayers 31 and 33 of the antireflection layer 3 are the 1 st low refractive index sublayers, and the surfaces thereof are nitrided, that is, the surface facing away from the substrate 1 is nitrided. In addition, the sublayer 35 serves as a 2 nd low refractive index sublayer on which the antifouling layer 4 is directly formed.

(examples 2 and 2)

In example 2-2, without performing step 107, a plastic lens having an antireflection layer 3 of 5-layer structure was produced in the same manner as in example 2-1 (sample S2-2). Therefore, in sample S2-2 of this example 2-2, of the silicon dioxide sub-layers 31, 33, and 35 included in the antireflection layer 3, only the innermost layer (the 1 st sub-layer) 31 (i.e., the sub-layer 31 of the antireflection layer 3 that forms the surface of the optical substrate 1) was subjected to the nitriding treatment to form the nitride-containing partial layer 39.

(examples 2 to 3)

In example 2-3, the step 104 was not performed, and a plastic lens having an antireflection layer 3 composed of 5 layers was produced in the same manner as in example 2-1 (sample S2-3). Therefore, in sample S2-3 of this example 2-3, of the silicon dioxide sub-layers 31, 33, and 35 included in the antireflection layer 3, only the 3 rd sub-layer 33 was subjected to nitriding treatment to form the nitride-containing partial layer 39.

(examples 2 to 4)

In examples 2 to 4, steps 102 to 110 were performed to perform nitridation treatment on the silicon dioxide sublayers 31 and 33 included in the antireflection layer 3. However, for the nitridation processes of steps 104 and 107, an ion gun 70 is used instead of the plasma generation device 60. Thus, nitrogen 64a and oxygen 63 were mixed in a ratio of 7: 3 into the ion gun 70, controlling the flow rate to 35SCCM, and irradiating the sublayers 31 and 33 with ionsAnd (4) shooting. The pressure in the chamber during the holding treatment was 4X 10^-3Ion irradiation was carried out for 5 minutes under conditions of ion irradiation at a frequency of 13.56MHz, an RF power of 450W, an accelerating voltage of 500V and a suppression voltage of 300V, simultaneously with Pa. The other points are the same as those in example 2-1.

Therefore, in sample S2-4 of this example 2-4, the silicon dioxide sublayers 31 and 33 of the antireflection layer 3 as the 1 st low refractive index sublayer, the surface of which is nitrided, that is, the surface facing away from the substrate 1, to form the nitride-containing partial layer 39. In addition, the sublayer 35 serves as a 2 nd low refractive index sublayer on which the antifouling layer 4 is directly formed.

(examples 2 to 5)

In example 2-5, the same steps 102 to 110 as in example 2-1 were performed, and the silicon dioxide sublayers 31 and 33 included in the antireflection layer 3 were nitrided. However, in step 110, a fluorine-containing organosilicon compound (trade name: OPTOOL DSX, a compound represented by the above general formula (1)) produced by Daikin Industries, Ltd. was used as the vapor deposition source 59a for forming the antifouling layer 4. Therefore, OPTOOL DSX was diluted with a fluorine-based SOLVENT (product name: DEmNAM SOLVENT manufactured by Daikin Industries, Ltd.) to prepare a solution having a solid content concentration of 3%, 1g of the solution was impregnated into porous ceramic particles (pellet) and the particles were dried, and the dried particles were used as a vapor deposition source 59a and fixed in a chamber CH 3.

Therefore, in sample S2-5 of this example 2-5, the silicon dioxide sublayers 31 and 33 of the antireflection layer 3 as the 1 st low refractive index sublayer, the surface of which is nitrided, that is, the surface facing away from the substrate 1, to form the nitride-containing partial layer 39. In addition, the sublayer 35 serves as a 2 nd low refractive index sublayer on which the antifouling layer 4 is directly formed.

(examples 2 to 6)

In examples 2 to 6, lenses having 7-layer structured antireflection layers were produced. Therefore, the process of nitriding the 5 th silicon dioxide sub-layer, the process of evaporating the 6 th sub-layer and the evaporation operation are addedIn step 110, the antifouling layer 4 is formed on the surface of the 7 th silica sublayer, which is the outermost 7 th silica sublayer. In addition, TiO is used in forming the high refractive index sub-layer₂To replace ZrO₂. The other points are the same as those in example 2-1. In the step of forming these high refractive index sublayers, TiO is deposited by ion accelerator deposition₂And (4) evaporation. The irradiation conditions at this time were adjusted to 13.56MHz, 450W RF power, 500V acceleration voltage and 300V suppression voltage by introducing 100% oxygen gas at a controlled flow rate of 35SCCM into the ion gun 70. The pressure in the chamber during the treatment was 4X 10^-3Pa. In this case, sublayer 1 (SiO)₂) Has a film thickness of 0.08 lambda and a 2 nd sublayer (TiO)₂) The film thickness of (2) is 0.07 lambda, the 3 rd Sublayer (SiO)₂) Has a film thickness of 0.10 lambda and a 4 th sublayer (TiO)₂) The film thickness of (2) is 0.18 lambda, 5 th Sublayer (SiO)₂) Has a film thickness of 0.07 lambda of sub-layer No. 6 (TiO)₂) The film thickness of (2) is 0.14 lambda, 7 th Sublayer (SiO)₂) The film thickness of (2) was 0.26. lambda.

Therefore, in sample S2-6 of this example 2-6, all the silica sub-layers except the outermost silica sub-layer included in the antireflection layer 3 were subjected to nitriding treatment to form the nitride-containing partial layer 39.

(examples 2 to 7)

In examples 2 to 7, the steps 104 and 107 of nitriding the layers 31 and 33 corresponding to the 1 st low refractive index sublayer were omitted, and instead, the layer 35 corresponding to the 2 nd low refractive index sublayer was nitrided, and then the antifouling layer 4 was formed, and by this manufacturing method, a plastic lens having the same composition as in example 2 to 1, i.e., having the antireflection layer 3 having a composition consisting of SiO and the antifouling layer 4 (sample S2-7) was manufactured (sample S2-7)₂And ZrO₂And (3) a 5-layer structure of high refractive index sublayers. The other points are the same as those in example 2-1.

(examples 2 to 8)

In examples 2 to 8, plastic lenses (samples S2 to 8) having the same composition as in examples 2 to 6 were produced, that is,has a structure formed by SiO₂And TiO and a low refractive index sublayer of₂And a 7-layer anti-reflection layer 3 composed of high refractive index sublayers, and nitriding only the uppermost sublayer of the anti-reflection layer 3 corresponding to the 2 nd low refractive index sublayer, and forming an antifouling layer 4 on the nitrided uppermost sublayer. The other points are the same as in examples 2 to 6.

Comparative example 2-1

In comparative example 2-1, steps 104 and 107 were not performed, and a plastic lens (sample SR 2-1) having the same composition as in example 2-1, i.e., having a composition consisting of SiO₂And ZrO₂The anti-reflection layer 3 and the anti-fouling layer 4 having a 5-layer structure composed of the high-refractive-index sub-layers of (a) and (b), and the nitriding treatment is not performed. The other points are the same as those in example 2-1. Therefore, in sample SR 2-1 of this comparative example 2-1, the nitridation treatment is not performed on all of the silicon dioxide sublayers 31, 33, and 35 included in the antireflection layer 3.

Comparative examples 2 and 2

In comparative example 2-2, a plastic lens (sample SR 2-2) having the same composition as in example 2-6, i.e., having a composition consisting of SiO₂And TiO and a low refractive index sublayer of₂And a 7-layer structure antireflection layer 3 made of a high refractive index sublayer, and the nitriding treatment is not performed. The other points are the same as in examples 2 to 6. Therefore, in the sample SR 2-2 of this comparative example 2-2, the nitridation treatment was not performed on all the silicon dioxide sublayers included in the antireflection layer 3.

(evaluation)

The scratch resistance and durability of the antifouling layer 4 of the samples S2-1 to S2-8 and SR 2-1 to SR 2-2 produced in examples 2-1 to 2-8 and comparative examples 2-1 to 2-2 were evaluated by the following methods. The evaluation results are shown in tables 2(a) and 2 (b).

For the evaluation of scratch resistance, steel wool (#0000) wound around a jig was reciprocated 50 times on the outermost surface of the antireflection layer 3 of each of samples S2-1 to S2-8 and SR 2-1 to SR 2-2 in a state of a load of 2 kg. The degree of scratch thus produced was compared with the standard sample, and the scratch resistance was evaluated on four scales of A, B, C and D. Where a indicates the best, B, C, D indicates the degradation sequentially.

In order to evaluate the durability of the antifouling layer 4, a cotton cloth loaded with 200g of weight was reciprocated 5000 times on the convex surface of the lens to be subjected to acceleration treatment. The antifouling performance before and after the accelerated treatment was evaluated by the contact angle and the wiping property of the oil-based ink. For the measurement of the contact angle, the contact angle of pure water was measured by a liquid drop method using a contact angle meter (Kyowa scienceco., ltd., model "CA-D Type"). For the wiping property of the oil-based ink, a black oil-based marker (manufactured by Zebra co., ltd., trade name: High Mackee Care) was used to draw a straight line of about 4cm on the convex surface of the lens and left for 5 minutes. Then, the mark portion was wiped with a wiping Paper (Nippon Paper Crecia Co., Ltd., trade name: K-Dry), and the wiping property of the oil-based ink was evaluated according to the following criteria.

O: wiping 10 times or less can completely remove the waste liquid.

And (delta): the wiping times are 11 to 20 times, so that the cleaning agent can be completely removed.

X: the unremoved portion remained after 20 times of wiping.

Tables 2(a) and 2(b) below are a summary of the evaluation results of the lenses obtained in the examples and comparative examples in the second embodiment.

TABLE 2(a)

TABLE 2(b)

In samples S2-1 to S2-8 of examples 2-1 to 2-8, at least one of the silica sub-layers was nitrided, and the samples were evaluated as good (A) or good (B) in the scratch resistance test. On the other hand, the samples SR 2-1 and SR 2-2 of comparative example 2-1 and comparative example 2-2, which were not nitrided, were evaluated as poor (D) in the scratch resistance test. As a result, it was found that the scratch resistance was improved by nitriding at least one of the silicon dioxide sublayers. In addition, the samples of examples 2-2 and 2-3 in which only one silicon dioxide sublayer was subjected to nitriding treatment were evaluated to be lower in the level of scratch resistance, B, than the samples of examples in which all the silicon dioxide sublayers except the outermost layer were subjected to nitriding treatment, but the level was within a completely allowable range.

Regarding the durability of the antifouling layer, samples S2-1 to S2-6 of examples 2-1 to 2-6 in which the uppermost low refractive index sublayer of the antireflection layer 3 was not subjected to nitriding treatment, and samples SR 2-1 and SR 2-2 of comparative examples 2-1 and 2-2 had sufficient durability without changing the wiping performance before and after the acceleration treatment. On the other hand, samples S2-7 and S2-8 of examples 2-7 and 2-8 in which the uppermost low refractive index sublayer of the antireflection layer 3 was subjected to nitriding treatment were sufficient in the wiping performance before the acceleration treatment, and the wiping performance after the acceleration treatment was lowered. From this, it is understood that the durability of the antifouling layer 4 can be greatly improved by not performing the nitriding treatment on the uppermost low refractive index sublayer 35 of the antireflection layer 3.

When the results were comprehensively evaluated, all of samples S2-1 to S2-8 of examples were excellent or good. Samples SR 2-1 to SR 2-2 of the comparative example were all X (failed). As a result, it was found that the scratch resistance was improved by nitriding at least one of the silicon dioxide sublayers. It is also understood that the wiping performance can be improved by not nitriding the uppermost low refractive index sublayer of the antireflection layer 3.

In addition, the second embodiment (example) described above relates to an optical article having an antireflection layer and an antifouling layer formed on a plastic spectacle lens having a hard coat layer, but for an optical article having a glass substrate, an antireflection layer may be formed on the substrate without the hard coat layer being sandwiched between the substrate and the antireflection layer. The optical article is not limited to a spectacle lens, but includes optical products such as an optical element of an image display device, a prism, an optical fiber, an element for an information recording medium, and an optical filter, and the manufacturing method disclosed in the above embodiment can be applied to these optical articles.

(third embodiment)

One of the inventions described in the third embodiment of the present invention (the first invention) relates to a method for producing an optical article having one or more thin films on an optical substrate, wherein the thin film of the outermost layer is a low refractive index thin film, and the surface of the low refractive index thin film is nitrided.

According to the first invention, the surface of the low refractive index film formed on the outermost layer of the optical substrate is nitrided, whereby the durability, particularly the scratch resistance, of the film can be improved.

A second invention (second invention) described in a third embodiment of the present invention is characterized in that, in the first invention, the low refractive index thin film is formed by vacuum deposition and then subjected to the nitriding treatment in which a gas containing nitrogen gas is introduced into a vacuum chamber in which the vacuum deposition is performed and subjected to a plasma treatment or an ion gun treatment.

According to the second invention, after the low refractive index thin film is formed on the optical substrate, a gas containing nitrogen is introduced into the vacuum chamber, and the surface of the low refractive index thin film can be nitrided by plasma treatment or ion gun treatment. Thereby improving the durability, particularly the scratch resistance, of the film.

A third invention (third invention) described in a third embodiment of the present invention is characterized in that the low refractive index thin film mainly composed of silica is formed in the first invention or the second invention.

According to the third aspect of the present invention, the durability, particularly the scratch resistance, of the optical article can be improved by nitriding the low refractive index thin film containing silica as a main component.

A fourth aspect of the invention described in the third embodiment of the present invention (fourth aspect) relates to an optical article having one or more thin films on an optical substrate, wherein a thin film forming an outermost layer in the thin film is a low refractive index thin film having a nitrogen-containing partial layer on a surface facing away from the optical substrate. The partial layer described herein in this application refers to a surface layer portion of the low refractive index film. The invention relates to nitriding the surface layer portion.

According to the fourth aspect of the present invention, the nitrogen-containing partial layer is formed on the surface of the low refractive index film of the outermost layer, whereby the durability, particularly the scratch resistance, of the optical article can be improved.

A fifth aspect of the invention (a fifth aspect) described in the third aspect of the invention is the fourth aspect of the invention, wherein the low refractive index thin film is formed mainly of silica.

According to the fifth aspect of the present invention, the thin film mainly composed of silica is nitrided, whereby the durability, particularly the scratch resistance, of the optical article can be improved.

In the third embodiment, the low refractive index thin film made of silicon dioxide or the like is nitrided, that is, the surface of the low refractive index thin film is wholly or partially nitrided to form a nitrogen-containing partial layer, so that the scratch resistance of the scratch-susceptible surface can be improved. In this case, the partial layer contains Si_sO_tN_u(s and u are positive integers, and t is an integer of 0 or more).

In the above production method, the surface of the low refractive index thin film such as silicon dioxide may be partially or entirely nitrided by introducing a gas containing nitrogen into a vacuum chamber and performing plasma treatment or ion gun treatment. Therefore, without precise film thickness control for introducing the nitrided layer, the nitrided film can be easily introduced even without controlling the ion current or precisely grasping the time, so that the scratch resistance of the antireflection layer can be improved. In particular, in plasma treatment, silicon nitride can be easily introduced into an apparatus for vacuum deposition or during deposition without using an ion source.

The low refractive index film made of silicon dioxide or the like described above may form part of various functional films, for example, part of an antireflection film. For low refractive index films composed of silicon dioxide, the presence of SiO in the partial layer formed is due to₂And Si_sO_tN_u(s and u are positive integers, and t is an integer of 0 or more), and therefore, the refractive index of the partial layer is in the range of 1.45 to 2.05, but the thickness and/or area thereof is limited, and therefore, the film design of the antireflection film is rarely affected.

Further, an antifouling film may be formed on the uppermost layer of the functional thin film. In this case, it is preferable to further form a low refractive index film on the nitrogen-containing partial layer of the low refractive index film. By not nitriding the silicon oxide of the uppermost layer on which the antifouling layer is laminated in this way, the abrasion resistance of the antifouling layer can be improved while maintaining the durability of the antifouling layer.

The composition suitable for forming the antifouling layer is a fluorine-containing silane compound, and one example of the fluorine-containing silane compound suitable for the antifouling layer is a compound represented by the above general formula (1).

Another example of the fluorine-containing silane compound suitable for the antifouling layer is a compound represented by the above general formula (2).

Fig. 7 is a schematic configuration diagram of a film formation apparatus 50 for forming various functional thin films formed on the surface of a substrate (workpiece) 40 placed on a support apparatus 80 by vacuum evaporation. The support means 80 is the same as that shown in figure 1. The film forming apparatus 50 has three chambers CH1, CH2, and CH3 through which the supporting apparatus 80 can pass. The chambers CH 1-CH 3 can be sealed with each other. The internal pressures of the chambers CH1 to CH3 are controlled by vacuum generators 52, 53, and 54, respectively. Chamber CH1 is an entrance or door chamber. The chamber CH2 is a second chamber for forming various functional thin films. In addition, a mass flow controller 66 for controlling the atmosphere in the chamber is connected to the chamber CH 2. The oxygen gas supply source 63, the argon gas supply source 64b, and the nitrogen gas supply source (not shown) are connected to a mass flow controller 66 so that the atmosphere in the chamber CH2 can be controlled to 100% oxygen gas, 100% argon gas, or 100% nitrogen gas, or a mixture of these gases in an appropriate ratio.

The chamber CH3 is a chamber for forming an antifouling layer by vapor deposition of a fluorine-containing silane compound. Therefore, the chamber CH3 has therein an antifouling layer vapor deposition source 59b impregnated with a fluorine-containing silane compound, a heater (halogen lamp) 68, and a compensation plate 67 for controlling the amount of discharge of the fluorine-containing silane compound by adjusting the opening degree. The chamber CH3 is maintained at an appropriate pressure by a vacuum generator 54 equipped with a rotary pump 54a, roots pump 54b, and turbo-molecular pump 54 c. In the case of forming the antifouling layer, the workpiece substrate 40 taken out from the chamber CH3 together with the supporting device 80 is placed in a constant temperature and humidity bath (not shown), and is annealed in an atmosphere of an appropriate humidity and temperature. The workpiece substrate 40 is left in the chamber for a predetermined time to be aged. In the case where the antifouling layer is not formed in the chamber CH3, the above-described annealing and aging are not required. Other structures and actions are the same as those of the film forming apparatus 50 of the first embodiment, and therefore, the same reference numerals are used in the drawings, and a repetitive description thereof will be omitted.

Fig. 8 is a flowchart showing a process of forming a single-layer low refractive index thin film in the film forming apparatus 50, taking as an example a process of forming a functional thin film on the work substrate 40. Fig. 9 is a sectional view showing the film structure of the optical article 10c according to the present embodiment.

When the optical substrate (base material) 1 is plastic, the hard coat layer 2 is formed on the optical substrate 1 before the low refractive index film 30 is formed in step 151. The hard coat layer 2 is formed in the same manner as in the above embodiment.

The substrate 1 on which the hard coat layer 2 is formed is fixed to a supporting device 80 as a work substrate 40 and conveyed to a film forming apparatus 50. In the film forming apparatus 50, the supporting apparatus 80 is first introduced into the chamber CH1 and degassed, and then the supporting apparatus 80 is moved into the chamber CH2 and plasma processing is performed in step 152. The purpose of this treatment is to clean the surface and thereby improve the adhesion between the hard coat layer 2 and the low refractive index film 30 on the substrate 1.

After forming a silicon oxide film as a low refractive index film in step 153, the surface is nitrided by plasma treatment or ion gun treatment in step 154, so that a nitride-containing partial layer 39 covering the whole or part of the surface (the surface facing away from the substrate 1) of the silicon oxide film 30 is formed. That is, the silicon oxide film 30 is a layer including a nitrided portion (surface nitrided layer). In this case, a gas containing nitrogen and having an arbitrary composition is used as the introduced gas, and examples thereof include 100% nitrogen, a mixed gas of nitrogen and oxygen, a mixed gas of nitrogen and argon, or a mixed gas of nitrogen, oxygen, and argon.

Since the functional thin film is formed on one surface of the optical article, the substrate 40 is reversed and fixed to the supporting device 80 in step 155, and steps 152 to 154 are repeated. When the functional thin films are formed on both sides of the substrate 40, the substrate 40 is taken out in step 156.

(example 3-1)

Several examples of manufacturing plastic spectacle lenses as optical articles according to the manufacturing method shown in fig. 8 will be described below. In the following examples and comparative examples, a plastic lens substrate for spectacles (manufactured by Seiko Epson Co., Ltd., trade name: Seiko super Sovereign) was used as the optical substrate 1. In step 151, a work substrate 40 having hard coat layers 2 formed on both sides of the base material 1 is used, and a silica thin film 30 as a low refractive index thin film is formed thereon.

The work substrate 40 is fixed to the dome 81 of the supporting device 80 with the concave surface facing downward, and then transferred to the film forming apparatusIs placed in 50. After degassing in the chamber CH1, in the chamber CH2, a step 152 was performed in which 100% argon gas was introduced while controlling the gas pressure to 4.0X 10^-2Pa while processing the workpiece substrate 40 with plasma generated by the high-frequency plasma generating device. Plasma treatment was performed for 1 minute under the condition of plasma generation at a frequency of 13.56MHz and a power of 400W. This treatment is intended to clean the substrate surface and improve the adhesion between the substrate 1 and the low refractive index film 30.

Next, step 153 is performed to perform vapor deposition of a silica thin film 30, the silica thin film 30 having a film thickness of 90nm, which exhibits excellent performance as a hard film and an antireflection film.

In the nitridation process of step 154, plasma generation device 60 is used. Therefore, after evaporation of the silica thin film, nitrogen and oxygen were mixed in a ratio of 7: 3 into chamber CH2, control: the gas pressure is 4.0 × 10^-2Pa, and generating plasma by using a high-frequency plasma generating device. Plasma treatment was performed for 5 minutes under the condition that plasma was generated at a frequency of 13.56MHz and a power of 600W. Thus, the nitride-containing partial layer 39 is formed on the surface of the silicon dioxide thin film 30.

The support device 80 moved into the chamber CH3 is then removed from the chamber, inverted and secured with the convex surface of the lens facing downward on the dome 81 of the support device 80, and the same process as described above is performed. (sample S3-1)

(examples 3 and 2)

In example 3-2, after the nitriding treatment in example 3-1, deposition of a silica thin film was performed again. This is effective for forming an antifouling layer on the nitrided silicon dioxide film 30, which nitrided silicon dioxide film 30 is a base layer (preparation layer) of the antifouling layer. The antifouling layer exhibits excellent durability as long as the film thickness of the silicon dioxide thin film (base layer) formed after the nitriding treatment is at least 5 nm.

Then, the supporting device 80 is moved into the chamber CH3, and the antifouling layer 4 is formed. As the vapor deposition source 59b, a fluorine-containing organosilicon compound (product name: KY-130, a compound represented by the general formula (2)) produced by Shin-etsu chemical co. KY-130 was diluted with a fluorine-based solvent (product name: Novec HFE-7200, manufactured by Sumitomo 3M, Ltd.) to prepare a solution having a solid content of 3%, 1g of the solution was immersed in porous ceramic particles (pellet) and the particles were dried, and the dried particles were fixed in a chamber CH3 using the deposition source 59 b. In the film formation process, a halogen lamp was used as the heater 68, and the particles as the evaporation source 59b were heated to 600 ℃ to evaporate the fluorine-containing organosilicon compound. The deposition time was 3 minutes.

The support device 80 in the chamber CH3 is then removed from the chamber, inverted and the convex surface of the lens is secured downwardly to the dome 81 of the support device 80, and the same process as described above is performed again. (sample S3-2)

Comparative example 3-1

In comparative example 3-1, a plastic lens not subjected to the nitriding treatment in example 3-1 was produced (sample SR 3-1).

Comparative examples 3 and 2

In comparative example 3-2, a plastic lens not subjected to the nitriding treatment in example 3-2 was produced (sample SR 3-2).

(evaluation)

The scratch resistance of samples S3-1, S3-2, SR 3-1 and SR 3-2 produced in examples 3-1 and 3-2 and comparative examples 3-1 and 3-2 was evaluated by the following method. The evaluation results are shown in Table 3.

For the evaluation of scratch resistance, steel wool (#0000) wound around a jig was reciprocated 50 times on the outermost surface of each of samples S3-1, S3-2, SR 3-1, and SR 3-2 under a load of 2 kg. The degree of scratch thus produced was compared with the standard sample, and the scratch resistance was evaluated on four scales of A, B, C and D. Where a indicates the best, B, C, D indicates the degradation sequentially.

TABLE 3

In the samples S3-1 and S3-2 of examples 3-1 and 3-2, the silicon dioxide thin film was nitrided, and therefore the evaluation of the scratch resistance test of the samples S3-1 and S3-2 was good (A). On the other hand, the samples SR 3-1 and SR 3-2 of comparative example 3-1 and comparative example 3-2, which were not nitrided, were evaluated as failed (D) in the scratch resistance test. As a result, it was found that the scratch resistance was improved by nitriding the silica thin film.

When evaluated comprehensively, all of the samples S3-1 and S3-2 of the examples were very good (excellent) as products. Samples SR 3-1 and SR 3-2 of the comparative example were all X (failed).

The third embodiment (example) described above relates to an optical article in which a functional film is formed on a plastic spectacle lens having a hard coat layer. For optical articles having a glass substrate, it is also possible to form an antireflection layer on the substrate without interposing a hard coat layer between the substrate and the antireflection layer. The third embodiment of the present invention relates to a structure in which a silicon dioxide thin film having a nitrided surface is formed on the outermost layer, but the same effects as those of the present embodiment can be obtained also when a thin film having 2 or more layers having an antireflection function is formed on the outermost layer. The optical article is not limited to a spectacle lens, but includes optical products such as an optical element of an image display device, a prism, an optical fiber, an element for an information recording medium, and an optical filter, and the manufacturing method disclosed in the above embodiment can be applied to these optical articles.

Claims (7)

1. An optical article having a layer comprising a nitrided portion, the nitrided portion being the surface of the layer on the side facing away from the optical substrate, the layer being in SiO_xIs a main component and is formed directly on the optical substrate or at least one other layer is sandwiched between the layer and the optical substrate.

2. The optical article of claim 1, wherein the nitrided portion is Si_sO_tN_uHere, s>0，t≧0，u>0。

3. The optical article according to claim 1, wherein the optical article has an antireflection layer formed directly on the optical substrate or sandwiching at least one other layer between the antireflection layer and the optical substrate, the antireflection layer including 2 or more sublayers, and an antifouling layer formed directly on the antireflection layer, wherein at least one of the sublayers other than an outermost layer of the antireflection layer is the layer including the nitrided portion.

4. The optical article according to claim 3, wherein the antireflection layer comprises 2 or more low-refractive-index sublayers and at least one high-refractive-index sublayer sandwiched between the 2 or more low-refractive-index sublayers, and one of the 2 or more low-refractive-index sublayers is the outermost layer, and at least one of the other layers of the 2 or more low-refractive-index sublayers is the layer containing the nitrided portion.

5. The optical article according to claim 1, wherein the optical article has an antireflection layer formed directly on the optical substrate or sandwiching at least one other layer between the antireflection layer and the optical substrate; the antireflection layer includes 2 or more sub-layers, and at least the uppermost layer among the 2 or more sub-layers is the layer including the portion subjected to the nitriding treatment.

6. A method of manufacturing an optical article having a functional layer which is formed directly on an optical substrate or which sandwiches at least one other layer between the functional layer and the optical substrate, and which functional layer comprises at least one sublayer; the manufacturing method includes a step of forming the functional layer, the step of forming the functional layer includes a layer forming step of forming a sub-layer included in the functional layer by vacuum deposition, and a nitriding step of nitriding a surface of the sub-layer obtained in the layer forming step.

7. The method for manufacturing an optical article according to claim 6, wherein the nitriding treatment step comprises: a gas containing nitrogen is introduced into the vacuum chamber in which the layer forming step is performed, and plasma treatment or ion gun treatment is performed.