Method of fabricating plastic lens

Abstract

To provide a method of fabricating a plastic lens which has an optical functional layer with superior adhesivity and offers superior productivity and improved durability.SOLUTION: A plastic lens fabrication method is provided, comprising a formation step of forming an undercoat layer and an optical functional layer on at least one surface of a resin lens body in the described order. The lens body is made of a thermoplastic acrylic resin with a glass transition temperature of 116°C or higher. The undercoat layer is formed by a resistance heating vacuum deposition method using SiO as a deposition material and controlling the amount of O2 gas to apply a pressure less than 3.0×10-2 Pa. The optical functional layer is formed by an electron beam heating vacuum deposition method, where premelting of a deposition material for the optical functional layer is performed before and after formation of the undercoat layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a plastic lens. [Background technology]

[0002] Acrylic resins, typified by polymethyl methacrylate (PMMA), are used as optical materials, etc., due to their high transparency, low birefringence, photostability, etc. For example, Patent Document 1 discloses a plastic lens in which an antireflection layer is formed on the surface of a PMMA substrate. Furthermore, in recent years, acrylic resins with excellent heat resistance have been developed in response to the need for application of acrylic resins to components of surveillance cameras, vehicle-mounted cameras, and the like, which are used in harsh environments such as high temperatures and high humidity and require higher durability than conventional cameras. For example, Patent Document 2 discloses a plastic lens using an acrylic resin with excellent heat resistance as a substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-273601 [Patent Document 2] International Publication No. 2023 / 074597 Summary of the Invention [Problem to be solved by the invention]

[0004] Electron beam heating vacuum deposition (dry deposition) is a common method for forming optical functional layers (anti-reflection layers, partial reflection layers, etc.) on resin substrates. However, it is generally known that this method is difficult to achieve good adhesion when the substrate is made of acrylic resin. To address this issue, the plastic lens described in Patent Document 1 improves adhesion by forming an undercoat layer primarily composed of silicon oxide between the PMMA substrate and the anti-reflection layer using a resistance heating vacuum deposition method. However, as a result of investigations by the present inventors, it has become clear that even when the undercoat layer is formed using the method described in Patent Document 1, peeling easily occurs depending on the anti-reflection layer formation conditions. Additionally, this plastic lens has the problem that the PMMA substrate has low heat resistance, making it unable to fully meet the durability required for in-vehicle cameras and the like. On the other hand, in the plastic lens described in Patent Document 2, a hard coat layer is formed between a substrate made of acrylic resin and an anti-reflection layer by a wet film-forming method to improve adhesion. However, the shape accuracy of the formed film surface is significantly inferior in wet film-forming methods compared to dry film-forming methods, so this method cannot be used for applications requiring high-precision control of the surface shape. In addition, there is a problem of poor productivity because a hard coat application, drying, and curing process is required between the lens substrate molding process and the anti-reflection layer deposition process.

[0005] Therefore, an object of the present invention is to provide a method for producing a plastic lens that has excellent adhesion of an optical functional layer, excellent productivity, and improved durability. [Means for solving the problem]

[0006] That is, the present invention is as follows. [1] A method for manufacturing a plastic lens, comprising a forming step of forming an undercoat layer and an optically functional layer in this order on at least one surface of a resin lens body, the lens body is made of a thermoplastic acrylic resin having a glass transition temperature of 116°C or higher, The undercoat layer is formed by a resistance heating type vacuum deposition method, and SiO is used as a deposition material for the undercoat layer. The amount of O gas is controlled to 3.0 × 10 -2 It is formed at pressures below 100 Pa, The optical functional layer is formed by an electron beam heating vacuum deposition method, and premelting of the deposition material of the optical functional layer is carried out both before and after forming the undercoat layer. A method for manufacturing a plastic lens. [2] The method for producing a plastic lens according to [1], wherein the premelting before the formation of the undercoat layer is carried out in a state where the lens is not placed in a vapor deposition apparatus. [3] The method for manufacturing a plastic lens according to [2], characterized in that after forming the undercoat layer, pre-melting of the meltable material among the vapor deposition materials of the optical functional layer is carried out so that the total EB energy (output wattage x time) is less than 1500 kJ. [4] The method for manufacturing a plastic lens according to [3], wherein the thickness of the undercoat layer is 200 nm or more and less than 1000 nm. [5] The thickness of the undercoat layer is 80 nm or more and less than 1000 nm, After forming the undercoat layer, a reflected electron trap is attached to the electron gun to be used. The method for manufacturing a plastic lens according to [3], [6] The method for producing a plastic lens according to [1], wherein the premelting before the formation of the undercoat layer is carried out while the lens is placed in a vapor deposition apparatus. [7] The method for manufacturing a plastic lens according to [6], characterized in that, before and after forming the undercoat layer, the pre-melting of the meltable material among the vapor deposition materials of the optical functional layer is carried out so that the total EB energy (output wattage x time) is less than 1500 kJ. [8] The thickness of the undercoat layer is 200 nm or more and less than 1000 nm, Before forming the undercoat layer, a reflected electron trap is attached to the electron gun to be used. The method for manufacturing a plastic lens according to [7], [9] The thickness of the undercoat layer is 80 nm or more and less than 1000 nm, Before and after forming the undercoat layer, a reflected electron trap is attached to the electron gun used. The method for manufacturing a plastic lens according to [7],

[10] The method for producing a plastic lens according to any one of [1] to [9], wherein the optical functional layer is any one of an anti-reflection layer, a partially reflective layer, and a highly reflective mirror.

[11] The method for manufacturing a plastic lens according to

[10] , characterized in that the formation of the optical functional layer includes a step in which the surface temperature of the lens body is 60°C or higher.

[12] The method for manufacturing a plastic lens according to

[11] , wherein the vapor deposition material pre-melted before the formation of the undercoat layer is used as it is without being processed in the pre-melt after the formation of the undercoat layer (in the vapor deposition step of the optical functional layer). [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for producing a plastic lens that has excellent adhesion of the optical functional layer, excellent productivity, and improved durability. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of an example of a plastic lens (plano-convex lens) formed by the manufacturing method of this embodiment, the cross section being parallel to and including the optical axis Z. [Figure 2]FIG. 2(a) is a schematic diagram (front view) of a typical vapor deposition apparatus having a resistance heating type vapor deposition source, and FIG. 2(b) is a schematic diagram (front view) of a typical vapor deposition apparatus having an electron beam heating type vapor deposition source. [Figure 3A] FIG. 3(a) is a flow diagram showing a film formation procedure in the manufacturing method of this embodiment when the premelt before the formation of the undercoat layer is performed in a state where the substrate is not placed in the deposition apparatus. [Figure 3B] FIG. 3(b) is a flow diagram showing a film formation procedure in the manufacturing method of this embodiment when a premelt is formed before the undercoat layer is formed while the substrate is placed in a vapor deposition apparatus. [Figure 4A] Figure 4(a) is a graph of EB output versus time for a program designed to achieve a total EB energy (output wattage x time) of 340 kJ for the pre-melt of the meltable material, which is one of the vapor deposition materials for the optical functional layer, and Figure 4(b) is a graph of EB output versus time for a program designed to achieve a total energy of 86 kJ. [Figure 4B] FIG. 4(c) is a graph of EB output versus time for a program designed to achieve a total energy of 640 kJ. DETAILED DESCRIPTION OF THE INVENTION

[0009] Below, we will explain in detail the form for implementing the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist. In the following, a structural unit constituting the polymer that forms the thermoplastic acrylic resin contained in the plastic lens of the present embodiment will be referred to as a "monomer unit" and / or a "structural unit" that includes a plurality of such "monomer units." Furthermore, the constituent material of such a "monomer unit" may be referred to simply as "monomer" without the "unit" part.

[0010] <Plastic lens> The plastic lens of this embodiment may be any of a biconvex lens, a plano-convex lens, a meniscus lens, a biconcave lens, a plano-concave lens, a flat lens, a cylindrical lens, a Fresnel lens, a lenticular lens, a fly's eye lens, a lens array, a microlens array, a prism lens, etc.

[0011] The method for manufacturing a plastic lens according to this embodiment will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a cross section of an example of a plastic lens (plano-convex lens) formed by the manufacturing method of this embodiment, the cross section being parallel to and including the optical axis Z. The plastic lens P formed by the manufacturing method of this embodiment includes at least a resin lens body P1, an undercoat layer P2 covering at least one side of the lens body (plastic lens substrate) P1, and an optical functional layer P3 covering the undercoat layer P2 from the side opposite to the lens body P1. That is, the plastic lens P of this embodiment has the undercoat layer P2 and the optical functional layer P3 laminated in this order on the lens body P1. The plastic lens P formed by the manufacturing method of this embodiment may further include, in addition to the undercoat layer P2 and the optical functional layer P3, other layers such as an antifouling layer for making the surface of the plastic lens P less susceptible to dirt, or a gas barrier layer for suppressing the penetration of water vapor into the plastic lens P. In this disclosure, a surface of a lens body refers to a surface or interface that exerts some optical effect, such as refraction or reflection, on a light ray or light beam incident on the surface. In the plastic lens P of FIG. 1, the surfaces of the lens body P1 are surface Sa and surface Sb, where surface Sa is aspherical with a radius of curvature R and surface Sb is planar (with a radius of curvature of ∞). The plastic lens P of FIG. 1 is an example in which only surface Sa is covered with an undercoat layer P2. In a plastic lens formed by the manufacturing method of this embodiment, only one of the multiple surfaces may be covered with an undercoat layer P2 and an optical functional layer P3, as shown in FIG. 1, or two or more surfaces may be covered with an undercoat layer P2 and an optical functional layer P3. In the manufacturing method of such a plastic lens P, as described below, after molding the lens body P1, an undercoat layer forming process for depositing an undercoat layer P2 and an optical function layer forming process for forming an optical function layer P3 are carried out in this order.

[0012] <Lens body P1> The lens body P1 contains a thermoplastic acrylic resin. The "thermoplastic acrylic resin" is an acrylic resin that has thermoplastic properties, and preferably also has heat resistance from the viewpoint of durability. "Heat resistant" means that the Vicat softening temperature measured in accordance with ISO 306 B50 is 110°C or higher, and "low heat resistance" means that the Vicat softening temperature is lower than 110°C. The thermoplastic acrylic resin may be used alone or in combination of two or more kinds.

[0013] [Thermoplastic acrylic resin] From the viewpoint of durability, the thermoplastic acrylic resin contained in the lens body P1 has a glass transition temperature (Tg) measured in accordance with JIS-K7121 of 116°C or higher, preferably 117°C or higher, and more preferably 118°C or higher. Furthermore, taking into consideration the moldability of the lens body P1 and the like, the glass transition temperature Tg is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower.

[0014] The thermoplastic acrylic resin contained in the lens body P1 is a polymer containing, as a monomer component, at least one ethylenically unsaturated monomer having a carboxyl group or a carboxylic acid ester group. It may be a homopolymer or copolymer of the ethylenically unsaturated monomer, or a copolymer of the ethylenically unsaturated monomer with another monomer copolymerizable with the ethylenically unsaturated monomer. The proportion of the ethylenically unsaturated monomer in the thermoplastic acrylic resin, based on 100% by mass of the thermoplastic acrylic resin, is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, and is preferably 100% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. A proportion of the ethylenically unsaturated monomer within the above range is preferable from the viewpoints of heat resistance, low birefringence, moldability, and color tone. The ethylenically unsaturated monomer having a carboxyl group or a carboxylic acid ester group is not particularly limited, and examples thereof include methacrylic acid, acrylic acid, methacrylic acid esters, and acrylic acid esters. Examples of the ester bond-forming residue in the carboxylic acid ester group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a tricyclodecyl group, an isobornyl group, a phenyl group, a benzyl group, a 1-phenylethyl group, a 2-phenoxyethyl group, a 3-phenylpropyl group, and a 2,4,6-tribromophenyl group.

[0015] From the viewpoint of heat resistance, the thermoplastic acrylic resin contained in the lens body P1 preferably has a ring structure in its structure. More specifically, it is preferable that the thermoplastic acrylic resin has a structural unit having a ring structure in its structure, and the structural unit having a ring structure preferably includes at least one structural unit selected from the group consisting of a cyclic imide structural unit, a lactone ring structural unit, an aromatic vinyl structural unit, and an alicyclic vinyl structural unit. The structural unit having a ring structure may be one type alone or a combination of two or more types.

[0016] The proportion of structural units having a ring structure in the thermoplastic acrylic resin is preferably 15% by mass or more, more preferably 16% by mass or more, even more preferably 17% by mass or more, and particularly preferably 18% by mass or more, based on 100% by mass of the thermoplastic acrylic resin. The proportion of the ring structure in the above range is preferred from the viewpoints of heat resistance, low birefringence, scratch resistance, and moldability.

[0017] Examples of the cyclic imide structural unit constituting the thermoplastic acrylic resin include a maleimide structural unit and a glutarimide structural unit.

[0018] (Maleimide structural unit) As the maleimide structural unit constituting the thermoplastic acrylic resin, a structural unit represented by the following general formula (1) is suitable. [ka] In the general formula (1), R 1 represents any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms, and the alkyl group, alkoxy group, cycloalkyl group, and aryl group may have a substituent on a carbon atom.

[0019] The monomer for forming the maleimide-based structural unit is not particularly limited, and examples thereof include maleimide; N-alkyl group-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, and N-cyclohexylmaleimide; and N-aryl group-substituted maleimides such as N-phenylmaleimide, N-methylphenylmaleimide, N-ethylphenylmaleimide, N-butylphenylmaleimide, N-dimethylphenylmaleimide, N-hydroxyphenylmaleimide, N-methoxyphenylmaleimide, N-(o-chlorophenyl)maleimide, N-(m-chlorophenyl)maleimide, and N-(p-chlorophenyl)maleimide. From the viewpoints of imparting heat resistance and moist heat resistance, the above-mentioned monomers are preferably N-cyclohexylmaleimide, N-phenylmaleimide, N-methylphenylmaleimide, N-(o-chlorophenyl)maleimide, N-(m-chlorophenyl)maleimide, and N-(p-chlorophenyl)maleimide, and from the viewpoints of easy availability and imparting heat resistance, more preferably N-cyclohexylmaleimide and N-phenylmaleimide, and even more preferably N-phenylmaleimide. The maleimide structural unit may be one type alone or a combination of two or more types.

[0020] From the viewpoints of heat resistance, moldability, optical properties, and color stability, the content of the maleimide structural unit is preferably 0 to 50% by mass, more preferably 2 to 40% by mass, and even more preferably 5 to 30% by mass, relative to 100% by mass of the thermoplastic acrylic resin. In the present disclosure, the content of the structural units constituting the thermoplastic acrylic resin can be determined by the method described in the examples below.

[0021] (Glutarimide structural unit) The glutarimide structural unit constituting the thermoplastic acrylic resin may be formed after resin polymerization. As the glutarimide structural unit, a structural unit represented by the following general formula (2) is suitable. [ka] In the general formula (2), R 1 and R 2 are each independently a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group. Also, R 3 represents any one selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 18 carbon atoms. Particularly preferably, R 1 , R 2 , and R3 are all methyl groups. The glutarimide structural units described above may be of one type alone or a combination of two or more types.

[0022] From the viewpoints of heat resistance, moldability, and optical properties, the content of the glutarimide structural unit is preferably 0 to 50% by mass, more preferably 2 to 40% by mass, and even more preferably 5 to 30% by mass, based on 100% by mass of the thermoplastic acrylic resin.

[0023] The glutarimide structural unit can be obtained by known methods, such as a method of copolymerizing a (meth)acrylic acid ester and / or (meth)acrylic acid, followed by a reaction of ammonia or an amine with urea or unsubstituted urea at high temperature, a method of reacting a methyl (meth)acrylate-styrene copolymer with ammonia or an amine, or a method of reacting poly(meth)acrylic anhydride with ammonia or an amine. Specifically, the method described in US Pat. No. 4,246,374 to R.M. Kopchik can be mentioned.

[0024] In addition, glutarimide structural units can also be formed by imidizing an acid anhydride such as maleic anhydride, a half ester of the acid anhydride with a linear or branched alcohol having 1 to 20 carbon atoms, or an α,β-ethylenically unsaturated carboxylic acid.

[0025] Furthermore, another preferred preparation method includes a method in which a (meth)acrylic acid ester and, if necessary, an aromatic vinyl monomer or other vinyl monomers are polymerized, followed by an imidization reaction to obtain a resin containing the glutarimide structural unit. The imidization reaction may be carried out using an imidization agent, and if necessary, a ring closure promoter may be added. The imidization agent may be ammonia or a primary amine. Suitable primary amines include methylamine, ethylamine, n-propylamine, and cyclohexylamine. The method for carrying out the imidization reaction is not particularly limited, and conventionally known methods can be used, such as methods using an extruder, a horizontal twin-screw reactor, or a batch-type reaction tank. The extruder is not particularly limited, and a single-screw extruder, twin-screw extruder, or multi-screw extruder can be suitably used. More suitably, a tandem-type reactive extruder having two twin-screw extruders arranged in series can be used.

[0026] In addition to the imidization step, the production of the resin may include an esterification step in which the carboxyl groups of the resin are treated with an esterifying agent such as dimethyl carbonate, and in this case, a catalyst such as trimethylamine, triethylamine, or tributylamine may also be used in combination. The esterification step can be carried out using, for example, an extruder or a batch reaction vessel, similarly to the imidization step. In addition, for the purpose of removing excess esterifying agent, by-products such as methanol, or monomers, the apparatus used is preferably equipped with a vent port capable of reducing the pressure to atmospheric pressure or below.

[0027] (Lactone ring structural unit) The lactone ring structural unit constituting the thermoplastic acrylic resin may be formed after resin polymerization. As the lactone ring structural unit, a structural unit represented by the following general formula (3) is preferred. [ka] In the general formula (3), R 1 , R 2 , and R 3 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. The organic group may contain an oxygen atom. The lactone ring structural unit may be one type alone or a combination of two or more types.

[0028] From the viewpoints of heat resistance, moldability, and optical properties, the content of the lactone ring structural unit is preferably 0 to 50% by mass, more preferably 2 to 40% by mass, and even more preferably 5 to 30% by mass, based on 100% by mass of the thermoplastic acrylic resin.

[0029] The method for forming a thermoplastic acrylic resin containing a lactone ring structural unit is not particularly limited, but examples thereof include a method in which a monomer having a hydroxyl group in a side chain, for example, a monomer having a structure represented by the following general formula (4) (e.g., 2-(hydroxymethyl)methyl acrylate) is copolymerized with a monomer having an ester group, such as a (meth)acrylic acid ester monomer, and then the resulting copolymer is heat-treated in the presence or absence of a specific catalyst to introduce a lactone ring structure into the polymer. [ka]

[0030] In the general formula (4), R 1 represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group. R 2 represents a group having 1 to 12 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms, and the hydrocarbon group may be substituted with, for example, a hydroxyl group. Particularly preferably, R 1 is a hydrogen atom, and R 2 is a methyl group.

[0031] Furthermore, the monomer having the structure represented by general formula (4) may remain unreacted in the thermoplastic acrylic resin, as long as the effects of the present invention can be achieved.

[0032] (aromatic vinyl structural unit) As the aromatic vinyl structural unit constituting the thermoplastic acrylic resin, a structural unit derived from an aromatic vinyl monomer represented by the following general formula (5) is preferably used. [ka] In the general formula (5), R 1 represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group. R 2 is any one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms, and an aryloxy group having 6 to 8 carbon atoms; R 2 may all be the same group or different groups. 2 They may combine together to form a ring structure. n represents an integer of 0 to 5;

[0033] The monomer for forming the aromatic vinyl structural unit is not particularly limited, but examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, and isopropenyloctylbenzene. Among the above, styrene and isopropenylbenzene are preferred, as they are excellent in terms of fluidity and polymerization conversion. Styrene is more preferred from the viewpoint of reducing unreacted monomers by improving the polymerization rate. These may be appropriately selected depending on the properties required for the thermoplastic acrylic resin of this embodiment. The aromatic vinyl structural units described above may be of one type alone or a combination of two or more types.

[0034] From the viewpoints of heat resistance, moldability, and optical properties, the content of the aromatic vinyl structural unit is preferably 0 to 50 mass%, more preferably 2 to 40 mass%, and even more preferably 4 to 30 mass%, relative to 100 mass% of the thermoplastic acrylic resin.

[0035] (alicyclic vinyl structural unit) The alicyclic vinyl structural unit constituting the thermoplastic acrylic resin may be formed after resin polymerization. As the alicyclic vinyl structural unit, a structural unit represented by the following general formula (6) is preferably used. [ka] In the general formula (6), R1 to R3 each independently represent a hydrogen atom, a chain hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, a silyl group, or a chain hydrocarbon group substituted with a polar group (a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, or a silyl group). Among these, a hydrogen atom or a chain hydrocarbon group having 1 to 6 carbon atoms is preferred due to its excellent heat resistance and low water absorption. Examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the chain hydrocarbon group substituted with a polar group include a halogenated alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms. Examples of the chain hydrocarbon group include an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms; and an alkenyl group having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, and more preferably 2 to 6 carbon atoms. In general formula (6), X represents an alicyclic hydrocarbon group, and the number of carbon atoms constituting the group is usually 4 to 20, preferably 4 to 10, and more preferably 5 to 7. By controlling the number of carbon atoms constituting the alicyclic structure within this range, birefringence can be reduced. Furthermore, the alicyclic structure is not limited to a monocyclic structure, and may be a polycyclic structure such as a norbornane ring or a dicyclohexane ring. The alicyclic hydrocarbon group may have a carbon-carbon unsaturated bond, but the content of such a bond is 10% or less, preferably 5% or less, and more preferably 3% or less of the total carbon-carbon bonds. By keeping the carbon-carbon unsaturated bond content of the alicyclic hydrocarbon group within this range, transparency and heat resistance are improved. Furthermore, the carbon constituting the alicyclic hydrocarbon group may be bonded to any of the following: a hydrogen atom, a hydrocarbon group, a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, a silyl group, and a linear hydrocarbon group substituted with a polar group (a halogen atom, an alkoxy group, a hydroxy group, an ether group, an ester group, a cyano group, an amide group, an imide group, or a silyl group). Among these, a hydrogen atom or a linear hydrocarbon group having 1 to 6 carbon atoms is preferred in terms of heat resistance and low water absorption.

[0036] Among the structural units represented by general formula (6), the structural unit represented by the following general formula (7) is excellent in heat resistance and low water absorption. [ka] In general formula (7), Ra, Rb, Rc, and Rd each independently represent a hydrogen atom or a lower chain hydrocarbon group, and a hydrogen atom or a lower alkyl group having 1 to 6 carbon atoms is preferred because it has excellent heat resistance and low water absorption. The above-mentioned alicyclic vinyl structural units may be used alone or in combination of two or more.

[0037] The method for forming a thermoplastic acrylic resin containing an alicyclic vinyl structural unit is not particularly limited, and examples thereof include (1) a method of copolymerizing an aromatic vinyl compound with another monomer containing (meth)acrylic acid or a (meth)acrylic acid ester, and hydrogenating the carbon-carbon unsaturated bonds in the main chain and aromatic ring, and (2) a method of copolymerizing an alicyclic vinyl compound with another monomer containing (meth)acrylic acid or a (meth)acrylic acid ester, and hydrogenating the same as necessary. Method (1) is preferred because it allows the production of an alicyclic hydrocarbon copolymer more efficiently. The aromatic vinyl compound used in the above method (1) is not particularly limited, but examples thereof include styrene, α-methylstyrene, α-ethylstyrene, α-propylstyrene, α-isopropylstyrene, α-t-butylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, monofluorostyrene, 4-phenylstyrene, and the like, and among these, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, and the like are preferred. The alicyclic vinyl compound used in the above method (2) is not particularly limited, but examples thereof include cyclobutylethylene, cyclopentylethylene, cyclohexylethylene (vinylcyclohexane), cycloheptylethylene, cyclooctylethylene, norbornylethylene, dicyclohexylethylene, α-methylcyclohexylethylene, α-t-butylcyclohexylethylene, cyclopentenylethylene, cyclohexenylethylene, cycloheptenylethylene, cyclooctenylethylene, cyclodekenylethylene, norbornenylethylene, α-methylcyclohexenylethylene, and α-t-butylcyclohexenylethylene, and among these, cyclohexylethylene (vinylcyclohexane) is preferred.

[0038] From the viewpoints of heat resistance, moldability, and optical properties, the content of the alicyclic vinyl structural unit is preferably 0 to 80 mass%, more preferably 2 to 60 mass%, and even more preferably 5 to 40 mass%, relative to 100 mass% of the thermoplastic acrylic resin.

[0039] [Method for producing thermoplastic acrylic resin] The method for producing the thermoplastic acrylic resin is not particularly limited as long as the above-mentioned thermoplastic acrylic resin can be obtained, and any conventionally known method can be used. For example, the thermoplastic acrylic resin can be produced by bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, or emulsion polymerization using the respective monomers for forming the above-mentioned structural units. For producing the thermoplastic acrylic resin, preferably, bulk polymerization or solution polymerization is used, and more preferably, solution polymerization is used. The thermoplastic acrylic resin may be produced either continuously or batchwise. In the method for producing the thermoplastic acrylic resin, it is preferable to polymerize the monomers by radical polymerization. In the method for producing the thermoplastic acrylic resin, known polymerization initiators, chain transfer agents, etc. may be used as needed.

[0040] [Additives] The lens body P1 is not particularly limited as long as it can exhibit the effects of the present invention, and may contain various additives. The additives are not particularly limited, and examples thereof include antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, release agents, lubricants, other thermoplastic resins, softeners / plasticizers such as paraffinic process oil, naphthenic process oil, aromatic process oil, paraffin, organic polysiloxane, and mineral oil, flame retardants, antistatic agents, inorganic fillers such as organic fibers and pigments such as iron oxide, compatibilizers, dispersants, reinforcing agents such as glass fibers, carbon fibers, and metal whiskers, colorants, organic phosphorus compounds such as phosphites, phosphonites, and phosphate esters, other additives, and mixtures thereof. The method for kneading the thermoplastic acrylic resin and the additives is not particularly limited, and examples thereof include kneading using a kneader such as an extruder, a heated roll, a kneader, a roller mixer, or a Banbury mixer. Among these, kneading using an extruder is preferred from the viewpoint of productivity. The extruder is preferably provided with a vent port for the purpose of reducing volatile content. The kneading temperature may be in accordance with the preferred processing temperature of the thermoplastic acrylic resin and other thermoplastic resins added as additives, and is generally 140 to 350°C, preferably 180 to 300°C.

[0041] From the viewpoint of ease of molding and mechanical strength, the resin composition containing a thermoplastic acrylic resin and optional additives preferably has a weight-average molecular weight (Mw) of 10,000 to 1,000,000, more preferably 50,000 to 500,000, and even more preferably 70,000 to 200,000. When the weight-average molecular weight (Mw) is within the above range, the lens body P1 tends to have a good balance between moldability and mechanical strength. Furthermore, from the viewpoints of ease of molding, mechanical strength, and solvent resistance, the resin composition containing a thermoplastic acrylic resin and optional additives preferably has a molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of 1.25 to 3.00, more preferably 1.50 to 2.75, and even more preferably 1.75 to 2.50. When the molecular weight distribution (Mw / Mn) is within the above range, the lens body P1 tends to have a good balance of moldability, mechanical strength, and solvent resistance. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the resin composition can be measured using gel permeation chromatography (GPC), specifically, by the method described in the examples below.

[0042] The lens body P1 is formed by molding a resin composition containing a thermoplastic acrylic resin and, optionally, additives. The lens body P1 can be manufactured by injection molding, compression molding, injection compression molding, extrusion molding, cast molding, vacuum molding, pressure molding, blow molding, cast molding, or other molding methods. Alternatively, the desired shape can be obtained by cutting, lathing, or polishing a resin block. Among these, injection molding is preferred from the viewpoint of productivity. The injection molding method and injection molding machine are not particularly limited, and conventionally known injection molding methods and injection molding machines can be used.

[0043] Typically, injection molding consists of (1) an injection process in which resin is melted and filled into the cavity of a temperature-controlled mold; (2) a pressure holding process in which pressure is applied to the cavity until the gate is sealed, and an amount of resin equivalent to the amount of molten resin filled in the injection process that contracts when it comes into contact with the mold and cools; (3) a cooling process in which the molded product is held until the resin cools after the pressure holding process is released; and (4) the mold is opened and the cooled molded product is removed.

[0044] In this case, the molding temperature is preferably in the range of Tg + 100°C to Tg + 180°C, and more preferably in the range of Tg + 110°C to Tg + 160°C, based on the glass transition temperature (Tg) of the resin composition. Here, the molding temperature refers to the cylinder setting temperature of the injection molding machine. The higher the molding temperature, the better the shape transferability of the lens body P1 obtained. However, at high temperatures, coloration due to thermal degradation during residence in the molding machine is accelerated, so the molding temperature should be selected appropriately. The mold temperature is preferably in the range of Tg-70°C to Tg, and more preferably in the range of Tg-50°C to Tg-10°C, based on the glass transition temperature (Tg) of the resin composition.

[0045] The injection speed can be appropriately selected depending on the thickness and dimensions of the lens body P1 to be obtained, and can be appropriately selected from the range of, for example, 2 to 1000 mm / sec. The pressure for maintaining the pressure can be appropriately selected depending on the shape of the lens body P1 to be obtained, and can be appropriately selected within the range of, for example, 30 to 150 MPa. Here, the pressure for holding pressure is the pressure maintained by a screw for further feeding the molten resin from the gate after the molten resin has been filled.

[0046] Furthermore, an annealing step may be performed to relieve residual stress caused by injection molding and reduce the phase difference of the lens body P1. The annealing temperature is preferably in the range of Tg-50°C to Tg, and more preferably in the range of Tg-30°C to Tg-10°C, where Tg is the glass transition temperature of the resin composition. may be used.

[0047] <Undercoat layer> In the plastic lens P formed by the manufacturing method of the present embodiment, the undercoat layer P2 is a layer that covers at least one surface of the lens body P1. The undercoat layer P2 enhances the adhesion between the lens body (plastic lens substrate) P1 and the optical functional layer P3, and suppresses the generation of cracks in the optical functional layer P3 in a high-temperature environment or a high-temperature and high-humidity environment. Therefore, the plastic lens P formed by the manufacturing method of the present embodiment is a lens with excellent durability.

[0048] The undercoat layer P2 is composed of silicon oxide SiO x (1 < x < 2). As will be described later, for example, when forming a film by vacuum deposition using SiO as a material, the film is formed while oxidizing the deposition material in an oxygen atmosphere, so that the composition of the undercoat layer P2 can be made silicon oxide SiO x (1 < x < 2). Generally, in a film-formed product in which an optical functional layer made of a metal oxide is formed on a resin substrate, when a damp heat test is performed, due to the difference in the linear expansion coefficient and water absorption rate between the resin substrate and the optical functional layer, the optical functional layer cannot follow the expansion of the resin substrate, and cracks occur. However, the plastic lens P formed by the manufacturing method of the present embodiment has an undercoat layer P2 composed of silicon oxide SiO x (1 < x < 2) as a buffer layer between the lens body P1 and the optical functional layer P3, so the occurrence of cracks is suppressed.

[0049] The refractive index of the undercoat layer P2 at a wavelength of 500 nm is preferably 1.44 or more, more preferably 1.45 or more, further preferably 1.46 or more, preferably 1.64 or less, more preferably 1.62 or less, and further preferably 1.60 or less. When the refractive index is within this range, a high suppression effect on crack generation after the damp heat test is exhibited. The above refractive index of the undercoat layer P2 is silicon oxide SiOx It can be controlled by adjusting the composition of (1 < x < 2). For example, when forming the undercoat layer P2 by the vacuum evaporation method described later, increasing the oxygen partial pressure (increasing the oxygen introduction amount) makes the composition closer to SiO2 and the refractive index lower, and decreasing the oxygen partial pressure (decreasing the oxygen introduction amount) makes the composition closer to SiO and the refractive index higher. The refractive index of the undercoat layer P2 can be measured by the method described in the examples below.

[0050] The thickness (film thickness) of the undercoat layer P2 is preferably 80 nm or more, more preferably 100 nm or more, further preferably 200 nm or more, preferably less than 1000 nm, more preferably 800 nm or less, and further preferably 650 nm or less. When the thickness (film thickness) of the undercoat layer P2 is within this range, as described later, when the optical functional layer P3 is formed by an electron beam heating type vacuum evaporation method, it is possible to prevent the reflected electrons from reaching the surface of the lens body P1. Therefore, it is possible to prevent the embrittlement of the lens body P1 due to the reflected electrons and the decrease in the adhesion between the lens body P1 and the optical functional layer P3 due to the embrittlement of the lens body P1. The thickness (film thickness) of the undercoat layer P2 can be determined, for example, by direct observation of the cross section with an electron microscope, ellipsometry, or spectroscopic reflectometry method, and specifically, it can be determined by the method described in the examples below.

[0051] The undercoat layer P2 is formed by a resistance heating type vacuum evaporation method. By using the resistance heating type, as described later, reflected electrons that cause embrittlement of the lens body P1 are not generated, so the adhesion between the lens body P1 and the undercoat layer P2 can be enhanced. The vacuum evaporation method is to heat the evaporation material in a vacuum chamber to vaporize or sublime it and deposit it on the surface of a substrate placed at a distant position in the chamber to form a thin film. An evaporation apparatus used in vacuum evaporation has a chamber and an evaporation source provided within the chamber, and a substrate on which a film is to be formed is held within the chamber. Examples of evaporation sources that can be used include resistance heating evaporation sources and electron beam heating evaporation sources. A schematic diagram of a typical evaporation apparatus is shown in FIG. 2. FIG. 2(a) shows an example of an evaporation apparatus having a resistance heating evaporation source, and FIG. 2(b) shows an example of an evaporation apparatus having an electron beam heating evaporation source (electron gun). Although not shown, an evaporation apparatus equipped with both a resistance heating evaporation source and an electron beam heating evaporation source can also be used.

[0052] In the vapor deposition apparatus 11 of FIG. 2( a), 12 denotes a chamber, 13 denotes a resistance heating power supply, 14 denotes a vapor deposition dome, 15 denotes a boat, and 16 denotes a shutter. The resistance heating power supply 13 and the boat 15 are collectively referred to as a vapor deposition source. When the boat 15 is heated by the resistance heating power supply 13, the vapor deposition material 17 is heated by the heat and vapor is generated. The generated vapor reaches and deposits on a substrate 18 to be deposited on, which is held in the vapor deposition dome 14, thereby forming a thin film 19 made of the vapor deposition material 17. A plurality of boats 15 may be installed in the vapor deposition apparatus 11, which allows for an increase in the film thickness of the same vapor deposition material or for forming films from a plurality of vapor deposition materials (not shown).

[0053] In the deposition apparatus 20 shown in FIG. 2( b), reference numeral 21 denotes a chamber, 22 denotes an electron gun, 23 denotes an electron gun power supply, 24 denotes an evaporation dome, 25 denotes a crucible, 26 denotes a pole piece, and 27 denotes a shutter. The electron gun power supply 23, electron gun 22, and crucible 25 are collectively referred to as the evaporation source. An electron beam 32 generated by the electron gun 22 is deflected by 150° or more (e.g., 180° or 270°) due to the action of a magnetic field formed by the pole piece 26, and is then irradiated onto an evaporation material 29 contained inside the crucible 25. When the electron beam 32 irradiates the evaporation material 29, the evaporation material 29 is heated and vapor is generated. The generated vapor reaches and deposits on a deposition target substrate 30 held within the evaporation dome 24, thereby forming a thin film 31 made of the evaporation material 29. A plurality of crucibles 25 are mounted on a rotating table, and by rotating the rotating table, any crucible can be positioned at the electron beam irradiation position (not shown).

[0054] As described above, when the electron beam 32 is incident on the deposition material 29, some of the irradiated electrons are reflected (backscattered) on the surface of the deposition material 29 due to the input power and material properties, resulting in the emission of a certain amount of reflected electrons 33. When the reflected electrons 33 reach the substrate 30 after repeatedly reflecting off the inner walls of the deposition apparatus, resin decomposition (embrittlement of the substrate 30) occurs, causing poor adhesion between the substrate 30 and the thin film 31 (the thin film 31 becomes more likely to peel from the embrittled portions of the substrate 30). Since acrylic resins are particularly susceptible to the effects of the reflected electrons 33 compared to other resins, it is necessary to suppress the effects of the reflected electrons 33 in order to obtain good adhesion. Effective countermeasures include making it more difficult for the reflected electrons 33 to reach the substrate 30 and reducing the amount of reflected electrons 33 generated. Increasing the thickness of the undercoat P2 is one method for making it difficult for the reflected electrons 33 to reach the substrate 30. As a result, even if a large number of reflected electrons 33 head toward the substrate 30, the undercoat layer P2 acts as a barrier layer, preventing them from reaching the surface of the acrylic resin (the interface with the undercoat P2), thereby suppressing embrittlement of the substrate 30. On the other hand, methods for reducing the amount of reflected electrons 33 generated include reducing the energy of the electron beam 32 incident on the deposition material 29 and capturing the generated reflected electrons 33 so that they do not head toward the substrate 30. The energy of the electron beam 32 incident on the deposition material 29 is determined by the output wattage of the electron beam 32 and its irradiation (incidence) time. Therefore, by reducing the output of the electron beam 32 or shortening the irradiation time during the film formation process, the amount of reflected electrons 33 generated can be reduced, thereby suppressing embrittlement of the substrate 30. Furthermore, in order to capture the generated backscattered electrons 33 so that they do not head towards the substrate 30, it is effective to provide a backscattered electron trap to the electron gun 22. This reduces the amount of backscattered electrons 33 heading towards the substrate 30, making it possible to suppress embrittlement of the substrate 30. In addition, the use of a backscattered electron trap is preferable because it can reduce the effects of backscattered electrons reaching the substrate, such as substrate damage and changes in thin film quality due to the increased temperature of the substrate. Any backscattered electron trap can be used as long as it has the ability to sufficiently capture backscattered electrons. Examples include physical barrier traps, which attenuate the energy of backscattered electrons by causing them to collide multiple times within an opening at the landing point of the backscattered electrons or within an L- or U-shaped barrier in the direction of their travel, and magnetic deflection traps, which deflect the direction of their travel using a magnetic field to capture them. When using a backscattered electron trap, the use of a magnetic deflection trap is preferred due to its high backscattered electron capture performance, and it is even more preferable to use a combination of a magnetic deflection trap and a physical barrier trap. The backscattered electron trap 28 in Figure 2(b) is an example of a magnetic deflection trap.

[0055] The general vacuum deposition steps for the undercoat layer P2 and the optical functional layer P3, which are optical thin films, include the following six steps. (1) The substrate is fixed to the deposition dome, and the deposition dome is placed at the top of the chamber. The chamber is evacuated to create a high vacuum. (2) The substrate is heated together with the deposition dome using a halogen heater, sheath heater, etc. At this time, the deposition dome is rotated while heating to ensure uniform heating. (3) With the shutter closed, the deposition material is melted (pre-melted). While sublimable materials such as SiO2 can be sublimated in granular form, pre-melting is not strictly necessary. However, pre-heating is recommended to ensure a smooth transition to the next step (4). (Hereinafter, melting and pre-heating will be collectively referred to as pre-melting.) For meltable materials such as Ti3O5, pre-melting is necessary to prevent bumping (splash) and stabilize the deposition rate. In the case of electron beam heating, reflected electrons may escape from the gap in the shutter during pre-melting, reach the substrate, and adversely affect adhesion. Therefore, low power and short time heating are recommended. (4) When the pressure inside the chamber reaches a predetermined vacuum pressure (base vacuum pressure) and the substrate temperature stabilizes, the shutter is opened and the atoms and molecules of the vaporized deposition material are deposited on the substrate surface (evaporation). (5) When a thin film of the desired thickness is formed on the substrate, the shutter is closed to terminate the deposition. (6) The vacuum is broken, and the deposition dome and the substrate on which the deposited thin film is formed are removed from the chamber.

[0056] Of the six steps described above, steps (1), (2), and (3) are usually performed simultaneously, followed by steps (4), (5), and (6) in that order. However, as described below, it is also possible to perform step (3) first, then open the deposition apparatus again, place the substrate, and perform steps (1) and (2) sequentially or simultaneously, before performing steps (3) and beyond again. In this case, it is optional to evacuate the chamber before performing step (3). In either procedure, heating the substrate in step (2) is optional and need not be performed. Furthermore, when forming a multilayer film using different deposition materials, steps (3) to (5) are repeated for the deposition of the second and subsequent materials (hereinafter, the deposition processes for the second and subsequent deposition materials will be referred to as (3)', (4)', and (5)'). In this case, premelting of the second and subsequent deposition materials (step (3)') may be performed simultaneously with premelting of the first material (step (3)). By performing step (3)' simultaneously with step (3), deposition of the second material (step (4)') can be immediately started after the deposition of the first material (step (4)) is completed, which has the advantage of efficiently carrying out the vacuum deposition of a multilayer film made of multiple materials.

[0057] In step (4), commonly known techniques include depositing oxide films by introducing oxygen into the chamber and reacting it with the atoms and molecules of the deposition material, or depositing a mixture film by simultaneously using multiple deposition materials. Other widely used techniques include ion-assisted deposition (IAD), which irradiates the surface of the thin film being deposited with ions to increase the packing density and improve adhesion, and ion plating, which passes gaseous deposition particles through plasma to give them a positive charge and then applies a negative charge to the substrate to attract and deposit the gaseous deposition particles.

[0058] In the deposition of the undercoat layer P2 of this embodiment, the chamber is evacuated in step (1), and the pressure in the chamber is set to 2.0×10 -3 It is preferable to evacuate the pressure to less than 100 Pa. In heating the deposition material in steps (3) and (4), methods such as resistance heating, electron beam heating, high-frequency induction heating, laser heating, etc. can be appropriately selected depending on the deposition material, the type of substrate, and the target characteristics of the thin film to be formed. In forming the undercoat layer P2 of this embodiment, SiO is used as the deposition material, and the heating method must be resistance heating, which does not generate reflected electrons, in order to prevent embrittlement of the lens body P1. In the deposition of step (4), oxygen can be introduced into the chamber to react with the atoms and molecules of the deposition material while forming the film. In the deposition of the undercoat layer P2 of this embodiment, the amount of oxygen introduced (amount of O2 gas) is controlled to maintain the pressure in the chamber at 3.0 × 10 -2 Pa or less than 2.8 x 10 -2 It is preferable that the pressure is less than 2.6×10 Pa. -2 It is more preferable that the pressure is less than 1.0×10 Pa. -2 Pa or more is preferable, and 1.1 × 10 -2 Pa or more is more preferable, and 1.2 × 10 -2 It is more preferable that the pressure inside the chamber is equal to or higher than Pa. When the pressure inside the chamber is within this range, an undercoat layer P2 having a desired refractive index is formed, and high adhesion and a high effect of suppressing cracking after a wet heat test are obtained.

[0059] <Optical functional layer> In the plastic lens P formed by the manufacturing method of this embodiment, the optical functional layer P3 is a layer that covers the undercoat layer P2 from the side opposite to the lens body P1. That is, the plastic lens P formed by the manufacturing method of this embodiment has the undercoat layer P2 and the optical functional layer P3 laminated in this order on at least one surface of the lens body P1. Examples of the optical functional layer P3 include an anti-reflection layer, a partial reflection layer, a high-reflection mirror, an ultraviolet cut filter, an infrared cut filter, a bandpass filter, a notch filter, an edge filter, and a dichroic mirror. In this embodiment, the optical functional layer P3 is formed as an anti-reflection layer, a partial reflection layer, or a high-reflection mirror. The anti-reflection layer prevents surface reflection in the plastic lens P. The partial reflection layer transmits and reflects a portion of incident light (an optical functional layer with approximately 50% transmission and reflection is specifically referred to as a half-mirror layer). The high-reflection mirror reflects most of the incident light. In this embodiment, the optical functional layer P3 is formed adjacent to the undercoat layer P2. Therefore, it is preferable to optically design the optical functional layer P3 taking into account the optical properties and thickness of the undercoat layer P2 so that the overall film configuration combining the undercoat layer P2 and the optical functional layer P3 exhibits the desired optical performance.

[0060] The optical functional layer P3 is preferably configured by combining a high-refractive index film made of a high-refractive index material with a low-refractive index film made of a low-refractive index material having a refractive index lower than that of the high-refractive index material. It is particularly preferable for the optical functional layer P3 to be configured as a dielectric multilayer film in which the high-refractive index film and the low-refractive index film are alternately stacked. When the optical functional layer P3 is a dielectric multilayer film with the above configuration, the reflectance can be more precisely adjusted for light rays and luminous fluxes in a wide range of wavelength bands.

[0061] Known materials can be used as the high-refractive index material for forming the high-refractive index film. Specific examples include titanium oxide, zirconium oxide, tantalum pentoxide, niobium pentoxide, zinc sulfide, cerium oxide, hafnium oxide, lanthanum titanate, antimony oxide, indium oxide, tin oxide, and mixtures thereof (e.g., Merck's Substance H series). Alternatively, materials sold in low oxidation states, such as Ti2O3 and Ti3O5, or metal materials, can be used as deposition materials. Oxide films containing any amount of oxygen can be formed by introducing oxygen into the deposition chamber. In the optical functional layer P3 of this embodiment, the high-refractive index film is preferably made of a high-refractive index material containing at least one of titanium oxide and zirconium oxide. Containing at least one of titanium oxide and zirconium oxide is preferable in terms of adhesion to the lens body P1 and undercoat layer P2, ease of material procurement, film stability, and controllability of optical properties in the visible light region. When the optical functional layer P3 includes multiple high-refractive-index films, the composition of each high-refractive-index film can be appropriately set according to the design of optical properties, and therefore the compositions of each high-refractive-index film may be the same or different.

[0062] The refractive index of each high refractive index film at a wavelength of 500 nm is preferably 1.80 or more, more preferably 1.90 or more, and even more preferably 2.00 or more, and is preferably 2.50 or less, more preferably 2.45 or less, and even more preferably 2.40 or less. The refractive index of the high refractive index film can be measured by the method described in the examples below.

[0063] The thickness (film thickness) of each high refractive index film is preferably 5 nm or more, more preferably 6 nm or more, and even more preferably 7 nm or more, and is preferably 150 nm or less, more preferably 140 nm or less, and even more preferably 130 nm or less. When the thickness (film thickness) of each high refractive index film is within this range, the balance between film adhesion, scratch resistance, and controllability of optical properties tends to be good. The thickness (film thickness) of the high refractive index film can be determined, for example, by direct observation of the cross section using an electron microscope, ellipsometry, or spectral reflectance analysis, and specifically, by the method described in the examples below.

[0064] Known materials can be used as the low-refractive index material for forming the low-refractive index film. Specific examples include silicon oxide, magnesium fluoride, yttrium fluoride, thiolite, cryolite, aluminum oxide, and mixtures thereof (e.g., Merck's Substance L series and M series). Alternatively, a commercially available material such as SiO or a metal material can be used as the deposition material, and an oxide film containing any amount of oxygen can be formed by introducing oxygen into the chamber during deposition. In the optical functional layer P3 of this embodiment, the low-refractive index film preferably contains silicon oxide (provided that its refractive index at a wavelength of 500 nm is lower than that of the undercoat layer P2). The low-refractive index film containing the silicon oxide is preferred in terms of ease of material procurement, oxidation controllability, and film formation stability. Methods for adjusting the refractive index of the low refractive index film containing silicon oxide to be lower than the refractive index of the undercoat layer P2 include, for example, using SiO2 as a vapor deposition material for silicon oxide in the optical functional layer P3, or adjusting the oxygen partial pressure (amount of oxygen introduced) when forming the undercoat layer P2, as described above.Increasing the oxygen partial pressure (increasing the amount of oxygen introduced) makes the composition closer to SiO2, lowering the refractive index, and decreasing the oxygen partial pressure (reducing the amount of oxygen introduced) makes the composition closer to SiO2, highering the refractive index. When the optical functional layer P3 includes multiple low refractive index films, the composition of each low refractive index film can be appropriately set according to the design of optical properties, and therefore the compositions of each low refractive index film may be the same or different.

[0065] The refractive index of each low refractive index film at a wavelength of 500 nm is preferably 1.10 or more, more preferably 1.20 or more, and even more preferably 1.30 or more, and is preferably 1.70 or less, more preferably 1.60 or less, and even more preferably 1.50 or less. The refractive index of the low refractive index film can be measured by the method described in the examples below.

[0066] The thickness (film thickness) of each low refractive index film is preferably 2 nm or more, more preferably 3 nm or more, and even more preferably 4 nm or more, and is preferably 200 nm or less, more preferably 190 nm or less, and even more preferably 180 nm or less. When the thickness (film thickness) of each low refractive index film is within this range, the balance between film adhesion, scratch resistance, and controllability of optical properties tends to be good. The thickness (film thickness) of the low refractive index film can be determined, for example, by direct observation of the cross section using an electron microscope, ellipsometry, or spectral reflectance analysis, and specifically, by the method described in the examples below.

[0067] The total thickness (total film thickness) of the optical functional layer P3 is preferably 100 nm or more, more preferably 150 nm or more, and even more preferably 200 nm or more, and is preferably 600 nm or less, more preferably 500 nm or less, and even more preferably 400 nm or less. When the total thickness (total film thickness) of the optical functional layer P3 is in this range, the adhesion of the optical functional layer P3 to the lens body P1 and the undercoat layer P2 tends to be good. The total thickness (total film thickness) of the optical functional layer P3 can be determined, for example, by direct observation of the cross section using an electron microscope, ellipsometry, or spectral reflectance method, and specifically, by the method described in the examples below.

[0068] The optical functional layer P3 of this embodiment is formed by vacuum deposition, similar to the undercoat layer P2, and is formed by electron beam heating vacuum deposition as a heating method for the deposition material. Generally, dry film-forming methods such as vacuum deposition are superior in shape control compared to wet film-forming methods. Therefore, the plastic lens P formed by the manufacturing method of this embodiment is a plastic lens with excellent shape precision that can be used for applications requiring high-precision surface shape control, since the undercoat layer P2 and the optical functional layer P3 are formed by vacuum deposition. Furthermore, the plastic lens P of this embodiment can be formed by continuously depositing the undercoat layer P2 and the optical functional layer P3 using vacuum deposition, thereby reducing the number of steps and working time, resulting in excellent productivity. In forming the optical functional layer P3 of this embodiment, an electron beam is used as a heating method for heating the deposition material in the above-mentioned vacuum deposition steps (3) and (4) because of its work efficiency and high degree of freedom in material selection. During this process, the temperature inside the chamber and on the lens body rises due to radiant heat from the deposition material, but from the viewpoint of adhesion, it is preferable that the surface temperature of the lens body be 60°C or higher. In the manufacturing method of this embodiment, premelting of the vapor deposition material for the optical functional layer P3 in step (3) is performed both before and after the formation of the undercoat layer P2. The vapor deposition material premelted before the formation of the undercoat layer P2 is used in its original state for premelting after the formation of the undercoat layer P2 without any processing. Although premelting is performed with a shutter closed, reflected electrons that escape through the shutter gap can reach the substrate and adversely affect adhesion, so measures such as reducing the amount of reflected electrons generated are necessary. In the manufacturing method of this embodiment, premelting the vapor deposition material for the optical functional layer P3 before the formation of the undercoat layer P2 allows the vapor deposition material to be densely packed in the crucible and the surface of the vapor deposition material to be leveled. This reduces the total EB energy (output wattage x time) required to heat the vapor deposition material during premelting after the formation of the undercoat layer P2, making it possible to suppress not only the generation and scattering of reflected electrons but also bumping of the vapor deposition material. However, since the pre-melting of the vapor deposition material for the optical functional layer P3 is carried out before the undercoat layer P2 has been formed, if a substrate is placed inside the vapor deposition device at that time, it will be directly affected by reflected electrons, and therefore the measures to prevent reflected electrons will vary greatly depending on the conditions for placing the substrate. In the case of the film formation flow shown in Figure 3(a), i.e., when the premelting of the vapor deposition material for the optical functional layer P3 is performed before the undercoat layer P2 is formed without the substrate being placed in the vapor deposition apparatus, no countermeasures are necessary because reflected electrons do not affect the substrate during this premelting. However, after the substrate is placed in the vapor deposition apparatus and the undercoat layer P2 is formed, the premelting of the vapor deposition material for the optical functional layer P3 is performed again. However, if the total EB energy (output wattage x time) is too high, too many reflected electrons will be generated, causing the undercoat layer to fail to function as a barrier layer and causing embrittlement of the substrate. Therefore, it is important to reduce the total EB energy during premelting. Specifically, the total EB energy during premelting of the meltable material for the vapor deposition material for the optical functional layer is set to less than 1500 kJ, and from the viewpoint of productivity, it is preferably less than 1250 kJ, and more preferably less than 1000 kJ. 4(a), (b), and (c) show examples of programs designed to achieve total premelting energies of 340 kJ, 86 kJ, and 640 kJ, respectively. Furthermore, because sublimable materials can be sublimated in granular form, premelting is not strictly necessary. However, if premelting is performed, it is preferable to use low energy to reduce reflected electrons and improve productivity. Furthermore, even with the above measures, if the undercoat layer P2 is thin, it is not possible to prevent the substrate from becoming brittle due to reflected electrons, resulting in easy peeling. Therefore, when the undercoat layer P2 is thin (e.g., preferably 80 nm or more, more preferably 100 nm or more), it is preferable to attach a reflected electron trap to the electron gun used to reduce the number of reflected electrons generated during premelting and reaching the substrate. When the thickness of the undercoat layer P2 is 200 nm or more, the undercoat layer P2 can prevent reflected electrons from reaching the substrate without reducing the number of reflected electrons, so there is no need to attach a reflected electron trap to the electron gun used, but there is no problem if one is attached. On the other hand, in the case of the film formation flow shown in Figure 3(b), i.e., when the premelting of the vapor deposition material for the optical functional layer P3 is performed while the substrate is placed in the vapor deposition apparatus before the undercoat layer P2 is formed, the influence of reflected electrons on the substrate is extremely large, making it essential to provide a reflected electron trap. However, a reflected electron trap cannot capture all reflected electrons, and since the undercoat layer (barrier layer against reflected electrons) P2 is not formed during this premelting process, if the total EB energy (output wattage x time) is too high, the reflected electrons will cause embrittlement of the substrate, so it is also important to reduce the total EB energy during premelting. Specifically, the total EB energy during premelting of the meltable material for the vapor deposition material for the optical functional layer is set to less than 1500 kJ, and from the viewpoint of productivity, it is preferably less than 1250 kJ, and more preferably less than 1000 kJ. 4(a), (b), and (c) are examples of programs designed to achieve total pre-melting energies of 340 kJ, 86 kJ, and 640 kJ, respectively. Among the deposition materials for the optical function layer, sublimable materials can be sublimated in a granular state, so strictly speaking, pre-melting is not required. However, if pre-melting is performed, it is preferable to use low energy to reduce reflected electrons and improve productivity. After the undercoat layer P2 is formed, the deposition material for the optical functional layer P3 is premelted again. However, if the total EB energy (output wattage x time) is too high, reflected electrons are generated, preventing the undercoat layer from functioning as a barrier layer and causing embrittlement of the substrate. Therefore, it is important to reduce the total EB energy during premelting, even after the undercoat layer P2 is formed. Specifically, the total EB energy during premelting of the meltable material of the deposition material for the optical functional layer is set to less than 1500 kJ, and from a productivity perspective, it is preferably less than 1250 kJ, and more preferably less than 1000 kJ. Figures 4(a), (b), and (c) show examples of programs designed to achieve total premelting energies of 340 kJ, 86 kJ, and 640 kJ, respectively. Furthermore, since the sublimable material of the deposition material for the optical functional layer can be sublimated in a granular state, premelting is not strictly necessary. However, if premelting is performed, it is preferable to use low energy to reduce reflected electrons and improve productivity. Furthermore, even if the above measures are taken, if the undercoat layer P2 is thin, it is not possible to prevent the substrate from becoming embrittled by reflected electrons, and peeling easily occurs, so if the undercoat layer P2 is less than 200 nm thick, it is necessary to continue to attach a reflected electron trap to the electron gun used to reduce the number of reflected electrons generated during premelting and reaching the substrate.If the undercoat layer P2 is 200 nm thick or more, the undercoat layer P2 can prevent reflected electrons from reaching the substrate without reducing the number of reflected electrons, so it is not necessary to continue to attach a reflected electron trap to the electron gun used, but there is no problem if it is attached. The amount of reflected electrons generated is determined by the magnitude of the EB energy, not the amount of evaporation material used. Therefore, the upper limit of the total EB energy during pre-melting (1500 kJ) is an absolute value that does not depend on the amount of evaporation material used or the number or size of the crucibles. If the requirement of less than 1500 kJ is satisfied, pre-melting of the evaporation material in steps (3) and (3)' may be performed on multiple crucibles containing the evaporation material for the optical functional layer P3 before step (4). The shape of the deposition material is not particularly limited for both the deposition material (SiO) of the undercoat layer P2 and the deposition material of the optical function layer P3, and can be appropriately selected in consideration of the specifications and characteristics of the deposition apparatus, the availability of the deposition material, etc. Specific examples include pellets, tablets, granules, powder, fan shapes, ring shapes, rod shapes, etc. In addition, in the deposition step (4), the pressure in the chamber is 1.0 × 10 -3 Pa ~ 5.0 × 10 -2 It is preferable to control the amount of oxygen introduced so that the pressure is within the above-mentioned range. The aforementioned ion-assisted deposition method can also be used, but the amount of introduced gas must be adjusted to achieve the above-mentioned pressure range, taking into account the pressure increase caused by the preferred introduced gas, oxygen gas, argon gas, or a mixture of these. Ion-assisted deposition produces dense films, which suppresses optical shifts caused by moisture adsorption. Furthermore, a high amount of introduced oxygen gas can efficiently oxidize oxygen-deficient compounds. However, there are problems such as changes in the refractive index, which can deviate from the desired optical properties, and excessive gas introduction can increase film density, leading to increased film stress and substrate deformation, film cracking, and peeling. A shortened mean free path of vaporized deposition particles can reduce the film formation rate, and the energy required to apply the deposition material to achieve a certain film thickness can increase. When using ion-assisted deposition, it is preferable to appropriately design and determine the type and amount of introduced gas, assist conditions, and film structure, taking into account the above-mentioned advantages and disadvantages.

[0069] <Articles using plastic lenses> The plastic lens of this embodiment can be suitably used for applications such as lenses in household products, office automation equipment, audiovisual equipment, battery electrical components, lighting equipment, and automobile components.

[0070] One suitable example is a lens for a head-mounted display (HMD) for virtual reality (VR). Because a head-mounted display is an image display device worn on the head, it is required to be small, lightweight, and comfortable to wear. As a means for miniaturizing the display, a method has been proposed in which a lens is combined with a quarter-wave plate and a reflective polarizing plate, etc., to change the polarization state of light after passing through the lens and switch between reflection and transmission, thereby causing the image to make one and a half round trips through a single lens (U.S. Patent No. 6,563,638, JP 2017-21321 A, etc.). The above method has the following mechanism, for example. A quarter-wave plate and a reflective polarizer are placed on the back of a lens with a partially reflective coating on the front surface. Circularly polarized light entering the front of the lens is converted to linearly polarized light by the quarter-wave plate after passing through the lens. This linearly polarized light is reflected by the reflective polarizer and converted again by the quarter-wave plate into the opposite circularly polarized light, which enters the lens from the back and reaches the partially reflective coating on the front surface. The light reflected by the partially reflective coating and exiting the back of the lens is converted by the quarter-wave plate into linearly polarized light with a 90° difference in direction from the original, passes through the reflective polarizer, and enters the eye as an image. In this way, a high magnification and wide field of view can be obtained even in a thin optical module.

[0071] If the polarization state changes while passing through the lens, for example, after the first time the light passes through the lens, some of the light will be transmitted through the reflective polarizing plate, and images with low and high magnifications will overlap, making it difficult to obtain a clear image, so a lens with low birefringence is required. In addition, since the influence on imaging performance due to changes in lens shape caused by humidity changes during use is also undesirable, a lens with low moisture absorption and high shape stability in high-temperature, high-humidity environments is required. In this regard, the plastic lens formed by the manufacturing method of this embodiment is suitable because it has excellent shape precision and extremely good durability.

[0072] Other examples of suitable uses of plastic lenses formed by the manufacturing method of this embodiment include lenses for household appliances, office automation equipment, audiovisual equipment, battery-powered electrical components, lighting equipment, and the like, such as lenses for smartphone cameras and tablet PC cameras, lenses used in telephoto cameras (periscope cameras) with curved optical systems; lenses used in VR (virtual reality), AR (augmented reality), MR (mixed reality), SR (substitutional reality), DR (diminished reality), and XR (cross reality) head-mounted displays, liquid crystal projectors, near-infrared sensors (LiDAR; light detection and ranging), and particularly small, thin, non-uniformly shaped optical lenses; lenses for optical communications; lenses, Fresnel lenses, phase plates equipped with microlens arrays, and the like.

[0073] Examples of lenses for automobile parts include lenses used in head-up displays and in-vehicle camera lenses (particularly front lenses). Other examples include lenses used in aerial displays, such as substrates for retroreflective sheets and partially transmissive mirrors, microlens arrays for constructing two-sided corner reflector arrays, and lenses for enlarging or reducing images or correcting image planes or aberrations. [Example]

[0074] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0075] The thermoplastic acrylic resins prepared in the production examples were measured and evaluated as follows.

[0076] Structural Unit Analysis Unless otherwise noted, 1 H-NMR measurement and 13The structural units of the thermoplastic acrylic resins produced in the Production Examples were identified by C-NMR measurement, and the amounts present were calculated. 1 H-NMR measurement and 13 The measurement conditions for C-NMR measurement are as follows: Measuring equipment: JEOL Ltd. ECZ400 Measurement solvent: CDCl3 or DMSO-d6 ·Measurement temperature: 40℃

[0077] [Molecular weight measurement] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the thermoplastic acrylic resins produced in the Production Examples were measured using the following apparatus and conditions. Measurement equipment: Tosoh Corporation, gel permeation chromatography (HLC-8320GPC) Measurement conditions: Columns: One TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were connected in series. Column temperature: 40℃ The developing solvent was tetrahydrofuran, the flow rate was 0.6 mL / min, and 0.1 g / L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard. Detector: RI (differential refractive index) detector Detection sensitivity: 3.0 mV / min Sample: 0.02 g of thermoplastic acrylic resin in 20 mL of tetrahydrofuran Injection volume: 10μL Standard sample for calibration curve: The following 10 types of polymethyl methacrylate (PMMACalibration Kit MM-10, manufactured by Polymer Laboratories) with known monodisperse weight peak molecular weights and different molecular weights were used. Weight peak molecular weight (Mp) Standard sample 1 1,916,000 Standard sample 2 625,500 Standard sample 3 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10,850 Under the above conditions, the RI detection intensity was measured against the elution time of the thermoplastic acrylic resin. Based on the calibration curve obtained by measuring the standard sample for the calibration curve, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the thermoplastic acrylic resin were determined, and the molecular weight distribution (Mw / Mn) was determined using these values.

[0078] [Measurement of glass transition temperature] The glass transition temperature (Tg) (°C) of the thermoplastic acrylic resin was measured in accordance with JIS-K7121. First, a sample was conditioned (left at 23°C for one week) under standard conditions (23°C, 50% RH), and four test pieces (four locations) of approximately 10 mg each were cut out. Next, using a differential scanning calorimeter (PerkinElmer Japan Co., Ltd. Diamond DSC) under conditions of a nitrogen gas flow rate of 25 mL / min, the sample was heated from room temperature (23 ° C) to 200 ° C (first heating) at 10 ° C / min, held at 200 ° C for 5 minutes to completely melt the sample, then cooled from 200 ° C to 40 ° C at 10 ° C / min, held at 40 ° C for 5 minutes, and heated again under the above heating conditions (second heating). The DSC curve drawn during this heating period was measured by measuring the intersection of the step-change curve during the second heating period with a line equidistant from each baseline extension in the vertical direction (midpoint glass transition temperature). Four measurements were performed per sample, and the arithmetic mean (rounded to the nearest whole number) of the four measurements was taken as the measured value.

[0079] [Vicat softening temperature measurement] The thermoplastic acrylic resin was placed in an injection molding machine (Shibaura Machine Co., Ltd., EC-100SX) and molded into Type 1A dumbbell test specimens in accordance with ISO 8257-2. The test specimens were conditioned in an oven at a specified temperature for 16 hours, then cooled in a desiccator at 23°C for 1 hour, and the Vicat softening temperature (°C) of the thermoplastic acrylic resin was measured in accordance with ISO 306 B50.

[0080] The raw materials used in the production examples are as follows:

[0081] [Monomer] Methyl methacrylate (MMA): manufactured by Asahi Kasei Corporation N-phenylmaleimide (phMI): Nippon Shokubai Co., Ltd. N-Cyclohexylmaleimide (chMI): Nippon Shokubai Co., Ltd. Methyl 2-(hydroxymethyl)acrylate (RHMA): Combi-Blocks Styrene (St): Fujifilm Wako Pure Chemical Industries, Ltd.

[0082] [Organic solvents] Meta-xylene (mXy): Mitsubishi Gas Chemical Company, Ltd. Toluene: Fujifilm Wako Pure Chemical Industries, Ltd. Methyl isobutyrate: manufactured by Kanto Chemical Co., Ltd.

[0083] [Polymerization initiator] 1,1-Di(t-butylperoxy)cyclohexane: NOF Corporation, Perhexa C t-Amyl peroxyisononanoate: Arkema Yoshitomi Co., Ltd., Luperox 570 t-Amylperoxy-2-ethylhexanoate: Arkema Yoshitomi Co., Ltd., Luperox 575

[0084] [Chain transfer agent] n-Octyl mercaptan: Chevron Phillips Chemical Company

[0085] [Other additives, etc.] Stearyl phosphate: Sakai Chemical Industry Co., Ltd., Phoslex A-18 Monomethylamine: Mitsubishi Gas Chemical Company, Inc. Dimethyl carbonate: Fujifilm Wako Pure Chemical Industries, Ltd. Triethylamine: Fujifilm Wako Pure Chemical Industries, Ltd. Pd / C:NE manufactured by Chemcat Corporation Rikemal H-100: manufactured by Riken Vitamin Co., Ltd.

[0086] (Production Example 1: Thermoplastic acrylic resin A) 358.6 kg of methyl methacrylate (hereinafter referred to as MMA), 29.4 kg of N-phenylmaleimide (hereinafter referred to as phMI), 67.7 kg of N-cyclohexylmaleimide (hereinafter referred to as chMI), 0.77 kg of n-octyl mercaptan as a chain transfer agent, and 224.3 kg of meta-xylene (hereinafter referred to as mXy) ​​were weighed and added to a 1.25 m 3 The mixture was added to the reactor and stirred to obtain a mixed monomer solution. Next, 88.0 kg of MMA, 6.3 kg of phMI, and 142.4 kg of mXy were weighed and added to Tank 1 with stirring to obtain a mixed monomer solution for addition. The liquid in the reactor was bubbled with nitrogen at a rate of 30 L / min for 1 hour, and the liquid in Tank 1 was bubbled with nitrogen at a rate of 10 L / min for 30 minutes to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the solution temperature in the reactor to 115°C, and polymerization was initiated by adding a polymerization initiator solution prepared by dissolving 0.470 kg of 1,1-di(t-butylperoxy)cyclohexane in 1.905 kg of mXy at a rate of 1.0 kg / hour while stirring at 50 rpm. During the polymerization, the solution temperature in the reactor was controlled at 115±2° C. by temperature regulation using a jacket. 30 minutes after the start of the polymerization, the addition rate of the initiator solution was reduced to 0.5 kg / hour. In addition, starting from 1 hour after the start of polymerization, the additional mixed monomer solution was added in its entirety from Tank 1 at a constant rate over a period of 4 hours. Furthermore, the addition rate of the initiator solution was reduced to 0.25 kg / hour 3.5 hours after the start of polymerization, and the addition was stopped 5 hours after the start of polymerization. After 12 hours had passed since the start of the polymerization, a polymer solution containing a thermoplastic acrylic resin having a ring structure in its structure (main chain) was obtained, and the polymerization was terminated. This polymer solution was fed to a concentration device consisting of a tubular heat exchanger preheated to 250°C and a vaporization tank, and devolatilization was carried out. The vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged with a gear pump, extruded through a strand die, cooled with water, and pelletized to obtain thermoplastic acrylic resin A. The composition of the resulting pellets was confirmed to be 81.0 mass% of structural units derived from MMA, 6.6 mass% of phMI, and 12.4 mass% of chMI monomers, respectively. The weight-average molecular weight was 108,000, the Mw / Mn ratio was 2.04, the glass transition temperature was 134°C, and the Vicat softening temperature was 124°C.

[0087] (Production Example 2: Thermoplastic acrylic resin B) Glutarimidated resin was produced using a 15 mm diameter, co-rotating, intermeshing twin-screw extruder. The raw resin was a methyl methacrylate-styrene copolymer (8% styrene by mass) with a molecular weight of 100,000 and monomethylamine as the imidizing agent. The temperature settings for each temperature control zone were 230–250°C, and the screw speed was 150 rpm. Methyl methacrylate-styrene copolymer (hereinafter also referred to as “MS resin”) was fed at a rate of 2 kg / hr. The resin was melted and filled using a kneading block, and then 8 parts by mass of monomethylamine was injected into the reaction zone through a nozzle. A reverse flight was installed at the end of the reaction zone to fill the zone with resin. Post-reaction by-products and excess monomethylamine were removed by reducing the pressure at the vent port to −0.092 MPa. The resin exited the die at the extruder outlet as strands, which were cooled in a water bath and pelletized using a pelletizer to obtain glutarimidated MS resin intermediate (1). Next, a 15 mm diameter co-rotating intermeshing twin-screw extruder was set at 230°C and 150 rpm for each temperature control zone. The glutarimidated MS resin intermediate (1) was fed from the hopper at a rate of 1 kg / hr. The resin was melted and filled using a kneading block. A mixture of 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine was then injected into the resin through a nozzle to reduce the carboxyl groups in the resin. A reverse flight was added to the end of the reaction zone to fill the resin. The post-reaction by-products and excess dimethyl carbonate were removed by reducing the pressure at the vent port to -0.092 MPa. The resin exiting the die at the extruder outlet as strands was cooled in a water bath and then pelletized using a pelletizer to obtain glutarimidated MS resin intermediate (2). The glutarimidated MS resin intermediate (2) was then fed into a 15 mm diameter, co-rotating, intermeshing twin-screw extruder with each temperature-controlled zone set at 230°C, a screw speed of 150 rpm, and a feed rate of 1 kg / hr. The pressure at the vent port was reduced to -0.095 MPa, and volatiles such as unreacted auxiliary materials were again removed. The devolatilized imide resin emerged as strands from the die at the extruder outlet and was cooled in a water bath. It was then pelletized in a pelletizer to obtain thermoplastic acrylic resin B (glutarimidated MS resin). The weight average molecular weight of thermoplastic acrylic resin B was 85,000, Mw / Mn was 1.8, the contents of monomer units in the copolymer were 8 mass% styrene units, 82 mass% MMA units, and 10 mass% glutarimide units, the glass transition temperature was 128°C, and the Vicat softening temperature was 120°C.

[0088] (Production Example 3: Thermoplastic acrylic resin C) A reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, a nitrogen inlet pipe, and a dropping pump was charged with 5.40 parts by mass of methyl 2-(hydroxymethyl)acrylate (hereinafter referred to as RHMA), 37.6 parts by mass of methyl methacrylate (hereinafter referred to as MMA), 0.450 parts by mass of styrene (hereinafter referred to as St), and 90.0 parts by mass of toluene, and the temperature was raised to 105°C while nitrogen was passed through. As an initial initiator, a solution consisting of 3.63 parts by mass of toluene and 0.245 parts by mass of t-amyl peroxy isononanoate was added dropwise over 9 minutes, while solution polymerization was carried out at 105°C to 110°C. Then, 11 minutes later, a solution consisting of 4.42 parts by mass of toluene and 0.298 parts by mass of t-amyl peroxy isononanoate was added dropwise over 180 minutes as a dropping initiator. Simultaneously with the addition of the dropping initiator, a solution consisting of 6.6 parts by mass of RHMA, 45.9 parts by mass of MMA, and 4.05 parts by mass of St was added dropwise over 180 minutes, while solution polymerization was carried out at 105°C to 110°C, and the mixture was then aged for another 100 minutes. To the obtained polymerization solution, a solution consisting of 1.20 parts by mass of toluene and 0.0750 parts by mass of stearyl phosphate was added as a catalyst (cyclization catalyst) for the cyclization condensation reaction, and the cyclization condensation reaction to form a lactone ring structure was allowed to proceed for 1.5 hours under reflux at approximately 90°C to 110°C. The resulting polymerized solution was then passed through a multi-tube heat exchanger maintained at 220°C to complete the cyclocondensation reaction. The polymerized solution was then introduced into a vented twin-screw extruder (L / D = 52) equipped with a leaf-disk polymer filter (filtration accuracy: 5 μm) at its tip at a processing rate of 90 parts by mass / hour (based on resin amount) to devolatilize the polymerized solution. The vented twin-screw extruder used had one rear vent and four fore vents (referred to as the first, second, third, and fourth vents from the upstream side). The barrel temperature was 220°C, and the vacuum level was 13.3 to 400 hPa (10 to 300 mmHg). During devolatilization, ion-exchanged water was introduced from behind the first, second, and third vents at a rate of 1.3 parts by mass / hour. The weight-average molecular weight of the obtained thermoplastic acrylic resin C was 102,000, Mw / Mn was 2.3, the glass transition temperature was 125°C, the Vicat softening temperature was 116°C, and the proportions of MMA units, styrene units, lactone ring structures, and RHMA units in the copolymer were 76.8% by mass, 4.6% by mass, 16.9% by mass, and 1.7% by mass, respectively.

[0089] (Production Example 4: Thermoplastic acrylic resin D) A monomer composition consisting of 75.09 parts by mass of MMA, 26.04 parts by mass of styrene, and 0.46 parts by mass of t-amylperoxy-2-ethylhexanoate as a polymerization initiator was continuously fed into a 10-L incomplete mixing vessel equipped with a helical ribbon impeller at a rate of 1 kg / h. Continuous polymerization was carried out at an average residence time of 2.5 hours and a polymerization temperature of 150°C. The liquid was continuously withdrawn from the bottom of the vessel to maintain a constant liquid level, and then fed to a concentrator consisting of a tubular heat exchanger and a vaporizer for devolatilization. The vacuum in the vaporizer was maintained at 10-15 Torr. The resin flowing down the vaporizer was discharged using a screw pump, extruded through a strand die, water-cooled, pelletized, and introduced into a solvent removal apparatus to obtain pelletized methyl methacrylate-styrene copolymer. This copolymer was dissolved in methyl isobutyrate to prepare a 10% by weight methyl isobutyrate solution. A 1000 mL autoclave was charged with 500 parts by weight of this 10% by weight methyl isobutyrate solution of this copolymer and 1 part by weight of 10% by weight Pd / C as a hydrogenation catalyst. The mixture was maintained at 200°C under a hydrogen pressure of 9 MPa for 15 hours to hydrogenate the aromatic double bonds in the styrene moieties of the copolymer. The hydrogenation catalyst was removed using a filter, and 0.04 parts by weight of Rikemal H-100 was added to the polymer solution and mixed. The mixture was then fed to a concentrator consisting of a tubular heat exchanger and a vaporizer for devolatilization. The vacuum in the vaporizer was set to 10-15 Torr. The resin flowing down the vaporizer was discharged using a gear pump, extruded through a strand die, cooled with water, and pelletized to obtain thermoplastic acrylic resin D. The composition of the resulting pellets was confirmed to be 73.2% by mass of MMA and 26.8% by mass of vinylcyclohexane monomer-derived structural units, respectively. The weight-average molecular weight was 148,000, the Mw / Mn ratio was 2.0, the glass transition temperature was 118°C, and the Vicat softening temperature was 112°C.

[0090] The methods for measuring and evaluating each layer formed in the examples and comparative examples are as follows.

[0091] [Refractive Index] The refractive index at a wavelength of 500 nm of each layer formed in the examples and comparative examples was determined by the spectral reflectance method after previously forming a single layer on a glass substrate (optical glass B270i) under the same film-forming conditions and measuring the spectral reflectance using an ultraviolet-visible-near-infrared spectrophotometer (UH4150, manufactured by Hitachi High-Tech Corporation).

[0092] [Thickness of each layer (film thickness)] The thickness (film thickness) of each layer formed in the examples and comparative examples was determined using a spectroscopic ellipsometer (UVISEL2, manufactured by Horiba, Ltd.) Note that the film thickness was calculated using data from a sample in which a single layer was formed on a glass substrate (optical glass B270i) under the same film formation conditions.

[0093] [Example 1] (Lens molding) Using the thermoplastic acrylic resin A obtained in Production Example 1, injection molding was performed using an injection molding machine (FANUC Corporation, S-2000i50B) to obtain a plano-convex lens molded product (lens body) with an optical axis thickness of 3.2 mm and an effective diameter of φ41 mm. As a result, one surface including the optical axis was aspherical with a radius of curvature R of 93.5 mm, a conic constant k of -1.12452, and no even-order constants were set. Furthermore, the other surface including the optical axis was flat with a radius of curvature of ∞. The cylinder temperature was set to Tg + 135°C of the thermoplastic acrylic resin A used, and the mold temperature was set to Tg - 15°C of the thermoplastic acrylic resin A used. The first holding pressure was set to 60 MPa for 4 seconds, and then the second holding pressure was set to 40 MPa for 3 seconds to relieve stress distortion inside the molded product. The injection speed was set to 10 mm / s.

[0094] (Deposition of undercoat layer and optical functional layer) An undercoat layer and an antireflection layer were formed as an optically functional layer on the flat surface of the above-mentioned lens molded article by vacuum deposition using a vacuum deposition apparatus (SAPIO SGC-1300, manufactured by Showa Vacuum Co., Ltd.) Note that the electron gun (EB source for vacuum deposition G-12100, manufactured by Plasmatech Co., Ltd.) was not equipped with a reflected electron trap. First, we pre-melted the meltable material from the deposition materials for the anti-reflection layer. While evacuating the vacuum chamber of the vacuum deposition equipment, we heated and melted Ti3O5 granules filled in a copper liner using an electron gun. As shown in Figure 4(a), we programmed the EB output and time so that the total EB energy (output wattage x time) was 340kJ. Specifically, the EB output was increased linearly from 0 kW to 4.0 kW over 20 seconds (until 20 seconds after the start of premelting (start of EB irradiation), then maintained at 4.0 kW for 20 seconds (from 20 seconds after the start to 40 seconds after the start), then increased linearly from 4.0 kW to 4.5 kW over 5 seconds (from 40 seconds after the start to 45 seconds after the start), then maintained at 4.5 kW for 20 seconds (from 45 seconds after the start to 65 seconds after the start), then increased linearly from 4.5 kW to 5.0 kW over 2 seconds (from 65 seconds after the start to 67 seconds after the start), then maintained at 5.0 kW for 20 seconds (from 67 seconds after the start to 87 seconds after the start) to terminate the premelting. The shutter was always closed, and no lens molded product was placed in the deposition apparatus. Next, the lens molded product is placed in the vacuum deposition device, and the vacuum chamber is heated to 1.5 x 10 -3 The chamber was evacuated to a pressure of 1.4 × 10 Pa. Next, SiO granules packed in a molybdenum boat were heated and sublimated by resistance heating to form an undercoat layer with a thickness of 320 nm. During film formation, oxygen gas was used as a reactive gas at a total pressure of 1.4 × 10 -2 The deposition material used in the next step of forming the anti-reflection layer was not pre-melted during the deposition of the undercoat layer. Next, the TiO material that was first pre-melted was reheated, re-melted, and vaporized using an electron gun, and a high refractive index TiO layer was formed by electron beam evaporation. During film formation, oxygen gas was used as the reactive gas at a total pressure of 1.3 × 10 -2The electron beam was introduced so that the EB power was 86 kJ, and the target (molded lens + undercoat layer) was not particularly heated when the film was being formed. Electron beam heating of the Ti3O5 deposition material was started with the shutter closed, and after a re-premelt of the deposition material was performed, the shutter was opened and film formation was carried out. The re-premelt was performed as shown in Figure 4(b), with a program set up according to the EB power and time, so that the total EB energy (output wattage x time) was 86 kJ. Specifically, the EB output was increased linearly from 0 kW to 2.5 kW over 10 seconds (until 10 seconds after the start) from the start of pre-melting (start of EB irradiation), then maintained at 2.5 kW for 5 seconds (from 10 seconds after the start to 15 seconds after the start), then increased linearly from 2.5 kW to 2.8 kW over 2 seconds (from 15 seconds after the start to 17 seconds after the start), then maintained at 2.8 kW for 6 seconds (from 17 seconds after the start to 23 seconds after the start), then increased linearly from 2.8 kW to 3.3 kW over 2 seconds (from 23 seconds after the start to 25 seconds after the start), and then maintained at 3.3 kW for 10 seconds (from 25 seconds after the start to 35 seconds after the start) to complete the pre-melting. Next, the SiO2 granules packed in the copper liner were heated and sublimated by an electron gun, and a low refractive index SiO2 layer was formed by electron beam evaporation. During film formation, oxygen gas was used as a reactive gas at a total pressure of 1.3 × 10 -2 The electron beam was introduced so that the target for deposition (molded lens product + undercoat layer + TiO2 layer) was not particularly heated when deposition was carried out. Furthermore, electron beam heating of the SiO2 deposition material began with the shutter closed, and after pre-melting of the deposition material was carried out, the shutter was opened and deposition was carried out. During this process, pre-melting was carried out by programming according to the EB output and time so that the total EB energy (output wattage x time) was 22 kJ. The above-described film formation of the TiO2 layer and the SiO2 layer was repeated three times alternately to form an antireflection layer having the structure shown in Table 1, thereby obtaining a plastic lens. Note that before and during the formation of the TiO2 layer, the vapor deposition material to be used in the subsequent process of forming the SiO2 layer was not pre-melted, and similarly, before and during the formation of the SiO2 layer, the vapor deposition material to be used in the subsequent process of forming the TiO2 layer was not pre-melted.

[0095] [Example 2] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that thermoplastic acrylic resin B was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0096] [Example 3] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that thermoplastic acrylic resin C was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0097] [Example 4] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that thermoplastic acrylic resin D was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0098] [Example 5] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the undercoat layer was formed to a thickness of 450 nm.

[0099] [Example 6] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the undercoat layer was formed to a thickness of 610 nm.

[0100] [Example 7] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the undercoat layer was formed to a thickness of 900 nm.

[0101] [Example 8] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that an undercoat layer was formed to a thickness of 100 nm and an electron gun equipped with a reflected electron trap was used as the electron gun for heating the deposition material.

[0102] [Example 9] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that an undercoat layer was formed to a film thickness of 100 nm, the pre-melted TiO material was re-pre-melted so that the total EB energy (output wattage x time) was 640 kJ, and an electron gun equipped with a reflected electron trap was used as the electron gun for heating the deposition material.

[0103] [Example 10] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the pre-melted TiO material was re-pre-melted so that the total EB energy (output wattage × time) was 640 kJ, and an electron gun equipped with a reflected electron trap was used as the electron gun for heating the deposition material.

[0104] [Example 11] When forming the undercoat layer, oxygen gas was used at a total pressure of 8.0 × 10 -3 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the amount of the compound introduced was Pa.

[0105] [Example 12] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the initial premelting of the TiO granules before forming the undercoat layer was carried out so that the total EB energy (output wattage × time) was 640 kJ. The pre-melting was performed according to the program shown in Figure 4(c). Specifically, the EB output was linearly increased from 0 kW to 3.5 kW over 15 seconds (until 15 seconds after the start of pre-melting). Then, it was maintained at 3.5 kW for 5 seconds (from 15 seconds after the start to 20 seconds after the start). Then, it was linearly increased from 3.5 kW to 7.0 kW over 5 seconds (from 20 seconds after the start to 25 seconds after the start). Then, it was maintained at 7.0 kW for 15 seconds (from 25 seconds after the start to 40 seconds after the start). Then, it was linearly decreased from 7.0 kW to 6.1 kW over 15 seconds (from 40 seconds after the start to 55 seconds after the start). Finally, it was maintained at 6.1 kW for 60 seconds (from 55 seconds after the start to 115 seconds after the start) to complete the pre-melting.

[0106] [Example 13] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that a partially reflective layer was formed as the optically functional layer.

[0107] [Example 14] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the initial pre-melting of TiO granules before forming the undercoat layer was carried out with the lens molded product placed in the deposition apparatus, and an electron gun equipped with a reflected electron trap was used as the electron gun for heating the deposition material.

[0108] [Example 15] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that thermoplastic acrylic resin B was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0109] [Example 16] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that thermoplastic acrylic resin C was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0110] [Example 17] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that thermoplastic acrylic resin D was used instead of thermoplastic acrylic resin A as the thermoplastic acrylic resin.

[0111] [Example 18] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the undercoat layer was formed to a thickness of 450 nm.

[0112] [Example 19] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the undercoat layer was formed to a thickness of 610 nm.

[0113] [Example 20] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the undercoat layer was formed to a thickness of 900 nm.

[0114] [Example 21] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the undercoat layer was formed to a thickness of 100 nm.

[0115] [Example 22] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that an undercoat layer was formed to a film thickness of 100 nm and the pre-melted TiO material was pre-melted again so that the total EB energy (output wattage × time) was 640 kJ.

[0116] [Example 23] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the pre-melted TiO material was re-pre-melted so that the total EB energy (output wattage × time) was 640 kJ.

[0117] [Example 24] When forming the undercoat layer, oxygen gas was used at a total pressure of 8.0 × 10 -3 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the amount of the compound introduced was Pa.

[0118] [Example 25] A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the initial premelting of the TiO granules before forming the undercoat layer was carried out so that the total EB energy (output wattage x time) was 640 kJ. The pre-melting was performed according to the program shown in Figure 4(c). Specifically, the EB output was linearly increased from 0 kW to 3.5 kW over 15 seconds (until 15 seconds after the start of pre-melting). Then, it was maintained at 3.5 kW for 5 seconds (from 15 seconds after the start to 20 seconds after the start). Then, it was linearly increased from 3.5 kW to 7.0 kW over 5 seconds (from 20 seconds after the start to 25 seconds after the start). Then, it was maintained at 7.0 kW for 15 seconds (from 25 seconds after the start to 40 seconds after the start). Then, it was linearly decreased from 7.0 kW to 6.1 kW over 15 seconds (from 40 seconds after the start to 55 seconds after the start). Finally, it was maintained at 6.1 kW for 60 seconds (from 55 seconds after the start to 115 seconds after the start) to complete the pre-melting.

[0119] [Example 26] A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that a partially reflective layer was formed as the optically functional layer.

[0120] [Comparative Example 1] When forming the undercoat layer, oxygen gas was used at a total pressure of 3.5 × 10 -2 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the amount of the compound introduced was Pa.

[0121] Comparative Example 2 A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the initial premelting of TiO granules before forming the undercoat layer was carried out with the lens molded article placed in the vapor deposition device, and that the premelting was carried out so that the total EB energy (output wattage x time) was 86 kJ. The pre-melting was performed according to the program shown in Figure 4(b). Specifically, the EB output was increased linearly from 0 kW to 2.5 kW over 10 seconds (until 10 seconds after the start of pre-melting). Then, it was maintained at 2.5 kW for 5 seconds (from 10 seconds after the start to 15 seconds after the start). Then, it was increased linearly from 2.5 kW to 2.8 kW over 2 seconds (from 15 seconds after the start to 17 seconds after the start). Then, it was maintained at 2.8 kW for 6 seconds (from 17 seconds after the start to 23 seconds after the start). Then, it was increased linearly from 2.8 kW to 3.3 kW over 2 seconds (from 23 seconds after the start to 25 seconds after the start). Finally, it was maintained at 3.3 kW for 10 seconds (from 25 seconds after the start to 35 seconds after the start) to complete the pre-melting.

[0122] Comparative Example 3 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the undercoat layer was formed to a thickness of 100 nm.

[0123] Comparative Example 4 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the undercoat layer was formed to a thickness of 20 nm.

[0124] Comparative Example 5 A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that an undercoat layer was formed to a thickness of 20 nm and an electron gun equipped with a reflected electron trap was used as the electron gun for heating the deposition material.

[0125] Comparative Example 6 When forming the undercoat layer, oxygen gas was used at a total pressure of 3.5 × 10 -2 A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that the amount of the introduced light was such that Pa was 100% and a partially reflective layer was formed as the optically functional layer.

[0126] Comparative Example 7 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 1, except that a thermoplastic acrylic resin with low heat resistance (Delpet 80N, manufactured by Asahi Kasei Corporation, Vicat softening temperature 109°C) was used instead of thermoplastic acrylic resin A.

[0127] [Comparative Example 8] When forming the undercoat layer, oxygen gas was used at a total pressure of 3.5 × 10 -2 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the amount of the compound introduced was Pa.

[0128] Comparative Example 9 A plastic lens provided with an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the undercoat layer was formed to a thickness of 20 nm.

[0129] [Comparative Example 10] When forming the undercoat layer, oxygen gas was used at a total pressure of 3.5 × 10 -2 A plastic lens having an undercoat layer and an optically functional layer was produced in the same manner as in Example 14, except that the amount of the introduced fluorine-containing compound was Pa and a partially reflective layer was formed as the optically functional layer.

[0130] [Comparative Example 11] A plastic lens provided with an undercoat layer and an optically functional layer was prepared in the same manner as in Example 14, except that a thermoplastic acrylic resin with low heat resistance (Delpet 80N, manufactured by Asahi Kasei Corporation, Vicat softening temperature 109°C) was used instead of thermoplastic acrylic resin A.

[0131] The plastic lenses produced in the examples and comparative examples were measured and evaluated as follows.

[0132] (Durability evaluation) (1) Initial adhesion To evaluate the coating adhesion of the plastic lenses obtained in the examples and comparative examples, a cross-cut test was performed according to JIS K 5600-5-6. A multi-blade cutting tool was used to create 25 1mm x 1mm grids on the flat side of the plastic lens, and cellophane tape ("LP-24" manufactured by Nichiban Co., Ltd.) was applied to the grids. The tape was then quickly removed, and the surface condition of the cross-cut area was observed to determine whether or not peeling of the film (undercoat layer and optical functional layer) had occurred. The results were classified as follows: Classification 0 or 1 was A (good), Classification 2 was B (practical), and Classifications 3 to 5 were C (poor). (classification) 0: The edges of the cut are completely smooth and there is no peeling on any of the squares. 1: There is slight peeling of the film at the intersection of the cuts. The percentage of peeling in the cross-cut area does not clearly exceed 5% of the total area of ​​the cross-cut area, assuming that the total area of ​​the cross-cut area is 100%. 2: The membrane has small peeling along the edges of the cuts and / or at the intersections. The percentage of peeling in the cross-cut area is clearly greater than 5% but not more than 15% of the total area of ​​the cross-cut, taken as 100%. 3: The membrane is partially or completely peeled along the edges of the cuts and / or partially or completely peeled in several squares. The percentage of peeling in the cross-cut area is clearly more than 15% but not more than 35% of the total area of ​​the cross-cut area, taken as 100%. 4: The membrane has partially or completely peeled off significantly along the edges of the cuts and / or partially or completely peeled off in several squares. The percentage of peeling in the cross-cut area is clearly more than 35% but not more than 65% of the total area of ​​the cross-cut area, taken as 100%. 5: Any degree of peeling that cannot be classified as category 4.

[0133] (2) Humidity and heat test A wet heat test was carried out using the plastic lenses obtained in the examples and comparative examples. The plastic lenses were placed in a thermo-hygrostat (PL-4KP manufactured by Espec Corporation) set to 85°C and 85% RH, and kept in an 85°C, 85% RH environment for 200 hours. The plastic lenses were then removed from the thermo-hygrostat and kept in a thermostatic chamber at 23°C and 50% RH for 24 hours. (2-1) Changes in appearance after moist heat test After the wet heat test, the surface of the plastic lens was visually observed to determine whether or not cracks had occurred. (2-2) Adhesion after moist heat test After the wet heat test, the plastic lenses were evaluated for adhesion of the films (undercoat layer and optical functional layer) using the same evaluation method as for the initial adhesion in (1).

[0134] The results of each measurement and evaluation are shown in Tables 1 and 2.

[0135] [Table 1]

[0136] [Table 2] [Industrial Applicability]

[0137] The plastic lens of the present invention has excellent productivity and excellent durability, and is therefore suitable for use as lenses in household products, office automation equipment, audiovisual equipment, battery-powered electrical components, lighting equipment, automobile parts, and the like. Lenses used in household goods, office automation equipment, audiovisual equipment, battery-powered electrical components, lighting equipment, etc. include, for example, lenses for smartphone cameras and tablet PC cameras, lenses used in telephoto cameras (periscope cameras) with curved optical systems; lenses used in VR (virtual reality), AR (augmented reality), MR (mixed reality), SR (alternative reality), DR (reduced reality), and XR (cross reality) head-mounted displays, liquid crystal projectors, near-infrared sensors (LiDAR), etc., particularly small, thin, non-uniformly shaped optical lenses; lenses for optical communications; lenses, Fresnel lenses, phase plates with microlens arrays, etc. Examples of lenses for automobile parts include lenses used in head-up displays and in-vehicle camera lenses (particularly front lenses). Other examples include lenses used in aerial displays, such as substrates for retroreflective sheets and partially transmissive mirrors, microlens arrays for constructing two-sided corner reflector arrays, and lenses for enlarging or reducing images or correcting image planes or aberrations. [Explanation of symbols]

[0138] P plastic lens P1 lens body P2 Undercoat layer P3 optical functional layer Sa, Sb plane Z optical axis 11 Vapor deposition equipment 12 chambers 13 Resistance heating power supply 14 Vapor deposition dome 15. Boat 16 Shutter 17 Vapor deposition materials 18. Substrate for film formation 19 Thin Film 20 Vapor deposition equipment 21 Chamber 22 Electron gun 23 Electron gun power supply 24 Vapor deposition dome 25 Crucible 26 pole pieces 27 Shutter 28 Backscattered electron trap 29 Vapor Deposition Materials 30 Substrate for film formation 31 Thin Film 32 Electron Beam 33 Backscattered electron

Claims

1. A method for manufacturing a plastic lens, comprising a forming step of forming an undercoat layer and an optically functional layer in this order on at least one surface of a resin lens body, the lens body is made of a thermoplastic acrylic resin having a glass transition temperature of 116°C or higher, The undercoat layer is formed by a resistance heating vacuum deposition method, and SiO is used as a deposition material for the undercoat layer, and O ２ Control the gas volume to 3.0 x 10 －２ formed at a pressure of less than 100 Pa, The optical functional layer is formed by an electron beam heating vacuum deposition method, and premelting of the deposition material of the optical functional layer is carried out both before and after forming the undercoat layer. A method for manufacturing a plastic lens.

2. 2. The method for producing a plastic lens according to claim 1, wherein the premelting before the formation of the undercoat layer is carried out in a state where the lens is not placed in a vapor deposition apparatus.

3. 3. The method for producing a plastic lens according to claim 2, wherein, after the undercoat layer is formed, pre-melting of the meltable material among the vapor deposition materials of the optical functional layer is carried out so that the total EB energy (output wattage x time) is less than 1500 kJ.

4. The method for manufacturing a plastic lens according to claim 3, wherein the thickness of the undercoat layer is 200 nm or more and less than 1000 nm.

5. The thickness of the undercoat layer is 80 nm or more and less than 1000 nm, After forming the undercoat layer, a reflected electron trap is attached to the electron gun to be used.

4. The method for manufacturing a plastic lens according to claim 3.

6. 2. The method for producing a plastic lens according to claim 1, wherein the premelting before the formation of the undercoat layer is carried out while the lens is placed in a vapor deposition device.

7. 7. The method for manufacturing a plastic lens according to claim 6, wherein, before and after forming the undercoat layer, pre-melting of the meltable material among the vapor deposition materials of the optical functional layer is carried out so that the total EB energy (output wattage x time) is less than 1500 kJ.

8. The thickness of the undercoat layer is 200 nm or more and less than 1000 nm, Before forming the undercoat layer, a reflected electron trap is attached to the electron gun to be used.

8. The method for manufacturing a plastic lens according to claim 7.

9. The thickness of the undercoat layer is 80 nm or more and less than 1000 nm, Before and after forming the undercoat layer, a reflected electron trap is attached to the electron gun used.

8. The method for manufacturing a plastic lens according to claim 7.

10. The method for manufacturing a plastic lens according to any one of claims 1 to 9, wherein the optical functional layer is any one of an anti-reflection layer, a partially reflective layer, and a highly reflective mirror.

11. The method for manufacturing a plastic lens according to claim 10, further comprising a step of raising the surface temperature of the lens body to 60°C or higher in forming the optical functional layer.

12. 12. The method for manufacturing a plastic lens according to claim 11, wherein the vapor deposition material pre-melted before the formation of the undercoat layer is used as it is without being processed in the pre-melt after the formation of the undercoat layer (in the vapor deposition step of the optical functional layer).

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