Molded body and method for producing molded body

Abstract

The present disclosure provides a molded body which has a surface on which high adhesion is exhibited in high-temperature high-humidity environments without the need of forming an adhesive layer on the molded body. A molded body according to one embodiment of the present disclosure is an optical molded body made of a polycarbonate resin, and has at least one first surface, which has a chemical composition that differs from the chemical composition of an inner portion of the molded body. The at least one first surface has a contact angle with water of 40-65°, a contact angle with ethylene glycol of 20-40°, and a contact angle with dimethylformamide of 0-20°.

Description

Formed body, and method for manufacturing formed body

[0001] The present disclosure relates to a formed body and a method for manufacturing the formed body.

[0002] Polycarbonate resin is used as a material for optical articles such as a light diffusion film, a lenticular, or a film with a hard coat. However, when a polycarbonate resin is adopted for a formed body used as an optical article, the formed body is likely to have scratches on the surface, which leads to deterioration of optical properties. Therefore, processing for the purpose of imparting surface morphology and preventing scratches is often performed on the formed body.

[0003] As an example of such processing, it is known to form a hard coat layer made of a cured resin by applying and curing an ultraviolet curable resin or a thermosetting resin on the surface of a formed body, and manufacture a laminate having the formed body and the hard coat layer. However, since polycarbonate resin has low solvent resistance and high hydrophobicity, the curable resin that can be used for coating and the solvent that dissolves it are limited. In addition, since the adhesion between the formed hard coat layer and the formed body also tends to be low, the hard coat layer easily peels off in a high temperature and high humidity environment.

[0004] As a technique for improving adhesion, techniques for treating the surface of a formed body by flame treatment, sandblasting, corona treatment, etc. are known. Further, as another technique for improving adhesion, Patent Document 1 discloses a technique for forming an adhesive layer excellent in hydrophilicity by causing a polymerization reaction on the surface of a formed body.

[0005] Japanese Patent Application Laid-Open No. 8-188658

[0006] However, among the techniques for improving adhesion as described above, flame treatment and sandblasting are unsuitable for manufacturing optical molded products because they physically roughen the surface of the molded product or deform it. Corona treatment tends not to achieve adhesion for a sufficient duration, and molded products manufactured using corona treatment will experience delamination of the hard coat layer in a short time when placed in a high-temperature, high-humidity environment. Furthermore, the technology described in Patent Document 1 forms an adhesive layer made of polymer between the molded product and the hard coat layer, complicating the layer structure of the resulting laminate, which makes it difficult to recycle defective products among the finished products and has the problem of a large environmental burden.

[0007] One aspect of this disclosure aims to provide a molded article having a surface that exhibits high adhesion in high-temperature and high-humidity environments without requiring the formation of an adhesive layer on the molded article.

[0008] To solve the above problems, a molded article according to one aspect of the present disclosure is a molded article made of polycarbonate resin for optical use, wherein the molded article has at least one first surface constituting at least a part of the surface of the molded article, the first first surface having a chemical composition different from the chemical composition of the interior of the molded article, and the contact angle of water on the at least one first surface is 40° or more and 65° or less, the contact angle of ethylene glycol is 20° or more and 40° or less, and the contact angle of dimethylformamide is 0° or more and 20° or less.

[0009] Furthermore, in order to solve the above problems, a method for manufacturing a molded article according to one aspect of the present disclosure is a method for manufacturing a molded article made of polycarbonate resin for optical use, characterized in that it includes a step of treating at least a part of the surface of a polycarbonate resin substrate that will be the base material of the molded article by bringing it into contact with a discharge plasma in an atmosphere containing a first gas consisting of at least one organic compound having carbon atoms, nitrogen atoms, and silicon atoms in its chemical structure.

[0010] According to one aspect of this disclosure, it is possible to provide a molded article having a surface that exhibits high adhesion in a high-temperature, high-humidity environment without the need to form an adhesive layer on the molded article.

[0011] These are the C1s spectra obtained by X-ray photoelectron spectroscopy on the treated surface of the molded articles of Example 1 and Comparative Example 1 of this disclosure.

[0012] [Molded Article] A molded article according to one aspect of the present disclosure will be described below. The molded article according to one aspect of the present disclosure is a molded article made of polycarbonate resin for optical purposes, and has at least one first surface constituting at least a part of the surface of the molded article, the first surface having a chemical composition different from the chemical composition of the interior of the molded article, and on at least one first surface, the contact angle of water is 40° or more and 65° or less, the contact angle of ethylene glycol is 20° or more and 40° or less, and the contact angle of dimethylformamide is 0° or more and 20° or less.

[0013] In one aspect of this disclosure, the molded article is made of polycarbonate resin. For example, the main part of the molded article, specifically 50% or more by mass, 60% or more by mass, 70% or more by mass, 80% or more by mass, 90% or more by mass, 95% or more by mass, or 99% or more by mass of the molded article, is made of polycarbonate resin.

[0014] The polycarbonate resin constituting the molded article may be any known polycarbonate resin. For example, a polycarbonate resin obtained by polymerizing a dihydroxy compound with phosgene or diphenyl carbonate may be used. Alternatively, a polycarbonate resin obtained using a compound having an isosorbide skeleton instead of a dihydroxy compound may be used. Examples of dihydroxy compounds include bisphenol A, hydroquinone, tetramethylbisphenol A, resorcinol, 4,4-dihydroxydiphenyl, N-phenylphenolphthalein, bisphenol TMC, and biscresolfluorene. Furthermore, the method for producing the polycarbonate resin is not particularly limited and examples include the phosgene method (interfacial polymerization method) and the melt polymerization method (transesterification method). The polycarbonate resin produced by the melt polymerization method may be subjected to treatment to adjust the amount of terminal hydroxyl groups.

[0015] The molded article may further contain components other than polycarbonate resin (hereinafter referred to as "other components"). An example of other components is an ultraviolet absorber.

[0016] Typically, the interior of a molded article may consist of a homogeneous system of polycarbonate resin, or a homogeneous system of polycarbonate resin and other components. In this specification, the interior of a molded article refers to at least a portion of the area inside at least one first surface. For example, the interior of a molded article is a region extending from at least one first surface of the molded article to a depth of 100 nm to 1000 nm. The chemical composition of the interior of a molded article can be analyzed by subjecting the portion of the newly exposed cross-section, obtained by cutting the molded article, that belonged to the region extending from at least one first surface of the molded article to a depth of 100 nm to 1000 nm before cutting, to various measurement methods.

[0017] In the chemical composition of the molded body analyzed by X-ray photoelectron spectroscopy (XPS), the carbon atom content (C) may be between 80 atomic percent and 90 atomic percent. Furthermore, in the chemical composition of the molded body analyzed by XPS, the nitrogen atom content (N) may be between 0 atomic percent and 2 atomic percent. In the chemical composition of the molded body analyzed by X-ray photoelectron spectroscopy, the silicon atom content (Si) may be between 0 atomic percent and 1 atomic percent.

[0018] The shape of the molded body is not particularly limited and can be appropriately selected depending on the application. The molded body may be, for example, a sheet, a block, or granules. If the molded body is a sheet, its thickness may be 5 μm or more and 2000 μm or less.

[0019] In one aspect of this disclosure, the molded article is for optical applications. In other words, the molded article has optical properties that are generally acceptable for a component of an article intended to transmit or diffuse light. The optical properties of the molded article may be set as appropriate depending on the specific article. For example, the haze of the molded article may be 0% or more and 95% or less. As another example, the transmittance of the molded article with respect to light at a wavelength of 600 nm may be 5% or more and 100% or less.

[0020] [First Surface] The molded article has at least one first surface which constitutes at least a portion of the surface of the molded article. The first surface may be a surface formed by processing the surface of a substrate which is a precursor of the molded article.

[0021] As described later, at least one first surface has a chemical composition different from the chemical composition of the interior of the molded body. However, since the region having a different chemical composition from the interior of the molded body as at least one first surface may be in an extremely small range, with a depth of approximately 100 nm or less, the environmental impact is small even if the molded body is recycled without removing the first surface from the interior of the molded body. Therefore, compared to molded bodies of the prior art in which an additional adhesive layer exhibits adhesion, the molded body according to one aspect of this disclosure does not require the removal of an additional layer for recycling, and can therefore be recycled with a simple process.

[0022] In this specification, the portion of the entire surface of a molded article that does not constitute a first surface is referred to as a "second surface." In this specification, if there is at least one second surface on the surface of a molded article and that at least one second surface separates two or more first surfaces from each other, each separated first surface is counted as one first surface.

[0023] At least one first surface may occupy the entire surface of the molded body or only a portion of it. For example, if the molded body is in the form of a sheet, at least one first surface may occupy both sides of the sheet, or it may occupy only one side of the sheet and the other side may be occupied by the second surface. Also, at least one first surface may occupy the entire surface of any of the surfaces of the sheet or only a portion of that surface. Since at least one first surface exhibits high adhesion, it is preferable to provide at least one first surface on the surface of the molded body in the portion that is to be bonded to other components.

[0024] (Contact angle on the first surface) On at least one first surface, the contact angle of a particular liquid is within a specific range. With this configuration, in a molded article according to one aspect of the present disclosure, at least one first surface exhibits high adhesion in a high-temperature, high-humidity environment.

[0025] On at least one first surface, the water contact angle is an indicator of the strength of hydrogen bonds between water molecules and can be an indicator of hydrophilicity. The water contact angle is 40° or more, preferably 43° or more. The water contact angle is 65° or less, preferably 60° or less, and more preferably 50° or less. Within these ranges, the smaller the water contact angle, the higher the hydrophilicity of at least one first surface, resulting in the effect of maintaining higher adhesion even in high temperature and high humidity environments.

[0026] On at least one first surface, the contact angle of ethylene glycol can be an indicator of the interaction between the polar ethylene glycol and the surface of the first surface. The contact angle of ethylene glycol is 20° or more, preferably 25° or more. The contact angle of ethylene glycol is 40° or less, preferably 32° or less. Within these ranges, the smaller the contact angle of ethylene glycol, the greater the effect of at least one first surface maintaining higher adhesion even in high temperature and high humidity environments.

[0027] On at least one first surface, the contact angle of dimethylformamide can be an indicator of polarity. The contact angle of dimethylformamide is 0° or greater, preferably 4° or greater. The contact angle of dimethylformamide is 20° or less, preferably 15° or less, and more preferably 10° or less. Within these ranges, the smaller the contact angle of dimethylformamide, the greater the effect of maintaining higher adhesion on at least one first surface even in high-temperature and high-humidity environments.

[0028] Furthermore, it is preferable that the value obtained by dividing the contact angle of dimethylformamide by the contact angle of water is 0.2 or less, as this allows for higher adhesion in high-temperature and high-humidity environments. Moreover, it is preferable that the value obtained by dividing the contact angle of dimethylformamide by the contact angle of ethylene glycol is 0.3 or less, as this also allows for higher adhesion in high-temperature and high-humidity environments.

[0029] In a molded article, the contact angles of water, ethylene glycol, and dimethylformamide serve as indicators of different properties, as described above. In one embodiment of this disclosure, by combining each of these indicators controlled to fall within a specific range, it is possible to impart high adhesion to the molded article in high-temperature and high-humidity environments.

[0030] In this specification, the contact angles of water, ethylene glycol, and dimethylformamide are measured by the methods described later in the examples.

[0031] (Chemical composition of the first surface) At least one first surface has a chemical composition different from the chemical composition of the interior of the molded article. In this specification, "at least one first surface has a chemical composition different from the chemical composition of the interior of the molded article" means that the chemical compositions analyzed by XPS on the first surface and the interior of the molded article are significantly different from each other.

[0032] In the chemical composition of at least one first surface analyzed by XPS, it is preferable that the ratio of nitrogen atoms (N) to carbon atoms (C), and the ratio of silicon atoms (Si) to carbon atoms (C), on an atomic percentage basis, be controlled within a specific range. By having the ratios N / C and Si / C within a specific range, at least one first surface exhibits higher adhesion in a high-temperature, high-humidity environment. The inventors of this application hypothesize the following principle: The ratios N / C and Si / C serve as indicators of the abundance of C-N-Si bonds or O-C-N-Si bonds in the molded article, and it is presumed that the higher the ratios N / C and Si / C, the greater the abundance of these bonds. Here, C-N-Si bonds or O-C-N-Si bonds exhibit high bond stability even in a high-temperature, high-humidity environment. Therefore, it is considered that the higher the ratios N / C and Si / C, the more stable the adhesion of the first surface is, even in a high-temperature, high-humidity environment. Furthermore, the lower the N / C ratio and Si / C ratio, the more likely it is that the adhesion of the first surface under high temperature and high humidity conditions will be similar to that of the surface of an untreated molded body under high temperature and high humidity conditions.

[0033] Furthermore, since C-N-Si bonds or O-C-N-Si bonds exhibit high stability in high-temperature and high-humidity environments, they are expected to contribute to maintaining the transparency of molded articles and mitigating yellowing of molded articles.

[0034] In the chemical composition of at least one first surface analyzed by XPS, the ratio of nitrogen atom content N to carbon atom content C (unit: %) on an atomic percentage basis is preferably within a specific range. Without limiting this disclosure, the ratio N / C is preferably 10 or more, more preferably 12 or more, and even more preferably 15 or more. Within this range, a higher ratio N / C results in at least one first surface exhibiting higher adhesion under high temperature and high humidity conditions. Without limiting this disclosure, the ratio N / C is preferably 30 or less, more preferably 28 or less, and even more preferably 25 or less.

[0035] In the chemical composition of at least one first surface analyzed by XPS, the ratio of silicon atoms (Si) to carbon atoms (C) on an atomic percentage basis (Si / C) is preferably within a specific range. Without limiting this disclosure, the Si / C ratio is preferably 5 or higher, more preferably 10 or higher, and even more preferably 11 or higher. Within this range, a higher Si / C ratio results in at least one first surface exhibiting higher adhesion under high-temperature and high-humidity conditions. Without limiting this disclosure, the Si / C ratio is preferably 40 or lower, more preferably 37 or lower, and even more preferably 35 or lower.

[0036] In the chemical composition of at least one first surface analyzed by XPS, the carbon atom content C is preferably 45 atomic percent or more, more preferably 50 atomic percent or more. Furthermore, the carbon atom content C is preferably 80 atomic percent or less, more preferably 70 atomic percent or less.

[0037] In the chemical composition of at least one first surface analyzed by XPS, the nitrogen atom content N is preferably 5 atomic percent or more, more preferably 7 atomic percent or more. Furthermore, the nitrogen atom content N is preferably 30 atomic percent or less, more preferably 15 atomic percent or less.

[0038] In the chemical composition of at least one first surface analyzed by XPS, the silicon atom content (Si) is preferably 3 atomic percent or more, more preferably 5 atomic percent or more. Furthermore, the silicon atom content (Si) is preferably 30 atomic percent or less, more preferably 25 atomic percent or less.

[0039] The spectrum of at least one first plane analyzed by XPS preferably has a peak or peak shoulder originating from a C-N-Si bond or an O-C-N-Si bond, more preferably a peak or peak shoulder originating from a C-N-Si bond. The presence of such a peak or peak shoulder indicates the presence of a C-N-Si bond or an O-C-N-Si bond on the first plane.

[0040] The spectrum of at least one first plane analyzed by XPS preferably has a peak or peak shoulder around 286.7 eV. The peak or peak shoulder observed around 286.7 eV may originate from a C-N-Si bond or an O-C-N-Si bond. In this specification, "around X eV" (where X represents any real number) refers to the range from (X-5) eV to (X+5) eV, including the endpoint.

[0041] In this specification, X-ray photoelectron spectroscopy (XPS) and the determination of the presence of peaks or peak shoulders in the spectra analyzed thereby are performed by the methods described later in the examples.

[0042] [Uses of Molded Articles] The uses of molded articles according to one aspect of this disclosure are described below. For the sake of convenience, the descriptions of components having the same function as those described above will not be repeated.

[0043] The molded body according to one aspect of the present disclosure can be used in various optical articles, and for example, it may be used as a member of an optical laminate.

[0044] As an example, the laminate may have the above-described molded body and a resin layer laminated on at least one first surface of the molded body. In such a laminate, the interface between the molded body and the resin layer exhibits high adhesion even in a high-temperature and high-humidity environment due to at least one first surface of the molded body. The resin contained in the resin layer can be appropriately selected according to the desired function of the resin layer. As an example, in order to make the resin layer function as a hard coat layer, the resin layer may contain an ultraviolet-curable resin or a thermosetting resin. As such an ultraviolet-curable resin, acrylic resin, epoxy resin, urethane acrylate resin, polyester resin, etc. are used. Among these, acrylic resin and epoxy resin are more preferable as optical materials with high transparency. Also, as such a thermosetting resin, epoxy resin, urethane resin, acrylic resin, silica hybrid resin, etc. are used.

[0045] As another example, the laminate may be formed by laminating two or more of the above-described molded bodies. Among them, adopting two or more molded bodies composed of different polycarbonate resins is advantageous from the viewpoint that it is possible to laminate two or more molded bodies having different optical properties such as refractive index, and to laminate other molded bodies after imparting a shape such as concave or convex to a surface different from the surface on which the molded bodies are laminated.

[0046] 〔Manufacturing method of molded body〕 The manufacturing method of the molded body according to one aspect of the present disclosure will be described below. For the sake of convenience of explanation, the description of members having the same functions as the above-described members will not be repeated.

[0047] The manufacturing method of the molded body according to one aspect of the present disclosure is a method for manufacturing an optical molded body made of polycarbonate resin, and includes a step of treating at least a part of the surface of a polycarbonate resin base material that becomes the base material of the molded body by bringing the base material into contact with discharge plasma in an atmosphere containing a first gas composed of at least one organic compound having a carbon atom, a nitrogen atom, and a silicon atom in its chemical structure.

[0048] A molded body manufactured by the manufacturing method according to one aspect of the present disclosure is also one aspect of the present disclosure. Further, the molded body can be used for manufacturing the laminate detailed above.

[0049] The manufacturing method according to one aspect of the present disclosure is a method for manufacturing an optical molded body made of a polycarbonate resin. Since the molded body to be manufactured has the same use and the composition of the polycarbonate resin constituting it as those of the molded body described above, the description thereof will not be repeated.

[0050] The manufacturing method includes a surface treatment step. The surface treatment step is a step of treating at least a part of the surface of the base material of the molded body by bringing the base material into contact with discharge plasma in an atmosphere containing a first gas.

[0051] The atmosphere of the surface treatment step contains a first gas. The first gas is composed of at least one organic compound having carbon atoms, nitrogen atoms, and silicon atoms in its chemical structure. When the organic compound constituting the first gas comes into contact with discharge plasma on at least a part of the surface of the base material, it binds to that part. This bond changes the chemical composition of that part, and as a result, that part becomes the first surface of the molded body to be manufactured. In other words, in a state where the first gas contained in the atmosphere is in contact with at least a part of the surface of the base material, when discharge plasma further comes into contact with these, that part is treated and becomes the first surface.

[0052] Examples of the organic compound include polysilazane or cyclopolysilazane. From the viewpoint of successfully forming the first surface on the surface of the base material, it is preferable that the organic compound has an N-Si bond in its chemical structure. Among the organic compounds having an N-Si bond in their chemical structure, from the viewpoint of being industrially easily available, it is preferable that the first gas is at least one selected from the group consisting of polysilazane and cyclopolysilazane. The organic compound constituting the first gas may be of one kind or a combination of two or more kinds.

[0053] The atmosphere in the surface treatment process may further contain a second gas that is inert to the first gas. The second gas may be used to adjust the total pressure of the atmosphere. Examples of the second gas include helium gas and argon gas. When the atmospheric pressure is normal or pressurized, the second gas is preferably helium gas, from the viewpoint that its mass is small and it is suitable for generating glow discharges.

[0054] When the atmosphere in the surface treatment process contains a gas other than the first gas, such as a second gas, the content of the second gas in the atmosphere can be appropriately selected. The content of the second gas is preferably 90% by volume or more, and more preferably 95% by volume or more. Within this range, the higher the content of the second gas, the more easily the discharge stabilizes.

[0055] The atmospheric pressure (gauge pressure) in the surface treatment process may be atmospheric pressure, reduced pressure, or increased pressure, and it is preferable to adjust the pressure so that a glow discharge that generates discharge plasma occurs in the atmosphere. From the viewpoint of reducing the limitations on the equipment used in the surface treatment process and enabling processing with a greater degree of freedom, the pressure is preferably atmospheric pressure or increased pressure. As an example of atmospheric pressure or increased pressure, the atmospheric pressure (gauge pressure) is preferably 0.1 Torr or more and 10 Torr or less, and more preferably 0.5 Torr or more and 2 Torr or less.

[0056] From the viewpoint of stabilizing the glow discharge, it is preferable that the first gas and the second gas are continuously supplied to the atmosphere of the surface treatment process.

[0057] The base material is an article that serves as a precursor to the molded product to be manufactured, and is made of polycarbonate resin. Since the polycarbonate resin described above can be used, its explanation will not be repeated. Furthermore, the shape of the base material may be the same as or close to the desired shape of the molded product to be manufactured.

[0058] The discharge plasma may be generated by means known in the art, and the means should be appropriately selected so that the discharge plasma by glow discharge is generated in the atmosphere.

[0059] As a power source for generating discharge plasma, a high-frequency power supply can be used as an example, and specifically, a radio frequency (RF) power supply may be used. The frequency of the power supply may be between 10 MHz and 200 MHz. The power of the power supply may be between 100 W and 2000 W.

[0060] A discharge device may be one equipped with a pair of electrode plates. An example of a pair of electrode plates is a stainless steel plate and an aluminum plate. Here, the stainless steel plate is used on the ground side. The aluminum plate is connected to the power supply and preferably has a thickness of about 1 mm. From the viewpoint of improving the stability of the discharge and the durability and stain resistance of the aluminum plate, it is preferable that an alumina layer is formed on the surface of the aluminum plate by oxidation treatment. The electrode plates may be arranged parallel to each other, and the distance between them may be 0.5 mm or more and 30 mm or less.

[0061] The electrode plates may be flat or cylindrical. By using a cylindrical electrode plate as at least one of the electrode plates and wrapping the base material around the cylindrical surface, it becomes possible to manufacture the molded body using a roll method. When using a pair of electrode plates, one being flat and the other cylindrical, it is preferable to position the flat plate parallel to the cylindrical direction of the cylindrical electrode plate.

[0062] The contact time between at least a portion of the substrate surface and the discharge plasma can be appropriately selected from a range commonly used in the art.

[0063] [Additional Notes] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0064] [Summary] As can be understood from the above explanation, this disclosure encompasses the following aspects:

[0065] Embodiment 1: A molded article made of polycarbonate resin for optical purposes, wherein the molded article has at least one first surface constituting at least a part of the surface of the molded article, the first surface having a chemical composition different from the chemical composition of the interior of the molded article, and the contact angle of water on the at least one first surface is 40° to 65°, the contact angle of ethylene glycol is 20° to 40°, and the contact angle of dimethylformamide is 0° to 20°. According to this embodiment, a molded article is provided that has a surface exhibiting high adhesion in a high-temperature, high-humidity environment without the need to form an adhesive layer on the molded article.

[0066] Embodiment 2: A molded article according to Embodiment 1, wherein, in the chemical composition of at least one first surface analyzed by X-ray photoelectron spectroscopy, the ratio of nitrogen atom content N to carbon atom content C (N / C) is 10 to 30 on an atomic percentage basis, and the ratio of silicon atom content Si to carbon atom content C (Si / C) is 5 to 40 on an atomic percentage basis. According to this embodiment, at least one first surface exhibits higher adhesion in a high-temperature, high-humidity environment.

[0067] Embodiment 3: A molded article according to Embodiment 1 or 2, wherein the spectrum of at least one first surface analyzed by X-ray photoelectron spectroscopy has a peak or peak shoulder originating from a C-N-Si bond. According to this embodiment, at least one first surface exhibits higher adhesion in a high-temperature, high-humidity environment.

[0068] Embodiment 4: A molded article according to any one of Embodiments 1 to 3, wherein the spectrum of at least one first surface analyzed by X-ray photoelectron spectroscopy has a peak or peak shoulder around 286.7 eV. According to this embodiment, at least one first surface exhibits higher adhesion in a high-temperature, high-humidity environment.

[0069] Embodiment 5: A laminate comprising a molded body according to any one of Embodiments 1 to 4, and a resin layer containing an ultraviolet-curing resin or a thermosetting resin, laminated on at least one first surface of the molded body. According to this embodiment, a laminate is provided in which delamination between the molded body and the resin layer in a high-temperature, high-humidity environment is reduced.

[0070] Embodiment 6: A laminate comprising two or more molded articles according to any one of Embodiments 1 to 4. According to this embodiment, a laminate is provided in which delamination between molded articles in a high-temperature, high-humidity environment is reduced.

[0071] Embodiment 7: A method for manufacturing a molded article made of polycarbonate resin for optical purposes, comprising the step of treating at least a portion of the surface of a polycarbonate resin substrate, which will be the base material of the molded article, by bringing it into contact with a discharge plasma in an atmosphere containing a first gas comprising at least one organic compound having carbon atoms, nitrogen atoms, and silicon atoms in its chemical structure. According to this embodiment, a molded article having a surface that exhibits high adhesion in a high-temperature, high-humidity environment can be manufactured without the need to form an adhesive layer on the molded article.

[0072] Embodiment 8: A method for producing a molded article according to Embodiment 7, wherein the organic compound is at least one selected from the group consisting of polysilazanes and cyclosilazanes. According to this embodiment, it is possible to successfully form a first surface on the surface of a substrate using materials that are readily available industrially.

[0073] An embodiment of this disclosure is described below. In the following embodiments and comparative examples, molded articles were manufactured under various manufacturing conditions. The contact angle, chemical composition, and adhesion under high temperature and high humidity conditions of the manufactured molded articles were also evaluated.

[0074] [Example 1] As a discharge device, a chamber was used which consisted of an electrically installed stainless steel plate and a 1 mm thick aluminum plate placed on top of the stainless steel plate. The two plates were arranged so that the contact surface in the thickness direction of the aluminum plate was parallel to the stainless steel plate, and the distance between the two plates was 1 mm. The aluminum plate used had alumina formed on its surface by oxidation treatment. An RF power supply was connected to the aluminum plate.

[0075] A mixed gas of 1.0 volume% polysilazane gas and 99.0 volume% helium gas was supplied to the discharge device. The flow rate of the mixed gas was adjusted so that the total pressure (gauge pressure) in the discharge device was 0.5 Torr. A sheet made of polycarbonate resin that had not undergone any processing other than molding was used as the base material. The sheet was placed on a stainless steel plate, and the RF power supply was operated at a frequency of 150 MHz and a power of 500 W to bring the discharge plasma from the glow discharge of the aluminum plate into contact with the side of the sheet facing away from the stainless steel plate. The sheet that had been in contact with the discharge plasma was recovered from the discharge device as the molded body of Example 1.

[0076] [Example 2] The same procedure as in Example 1 was performed, except that the RF power supply was operated at 250W, which was 0.5 times the original power, to obtain the molded body of Example 2.

[0077] [Example 3] The same procedure as in Example 1 was performed, except that the RF power supply was operated at 1000W (2.0 times the original power), to obtain the molded body of Example 3.

[0078] [Example 4] The same procedure as in Example 1 was carried out to obtain the molded article of Example 4, except that the composition of the mixed gas was changed to 0.5 volume% polysilazane gas and 99.5 volume% helium gas.

[0079] [Comparative Example 1] The same procedure as in Example 1 was performed to obtain the molded article of Comparative Example 1, except that the composition of the mixed gas was changed to 100.0 volume% helium gas.

[0080] [Comparative Example 2] The same procedure as in Example 1 was performed to obtain the molded article of Comparative Example 2, except that the composition of the mixed gas was changed to 1.0 volume% nitrogen gas and 99.0 volume% helium gas.

[0081] Hereinafter, of the two surfaces of the sheet-like molded body in the examples and comparative examples, the surface that came into contact with the discharge plasma will be referred to as the "treated surface".

[0082] [Evaluation Example 1: Contact Angle on the Treated Surface of the Molded Body] The contact angles of water, ethylene glycol (EG), and dimethylformamide (DMF) on the treated surface of the molded bodies in the examples and comparative examples were measured by the following method. The molded body was placed on a horizontal surface with the treated surface facing upwards. Next, water was dropped onto the treated surface from a vertical direction. After dropping, the contact angle between the treated surface and the water was measured using a contact angle meter (portable contact angle meter PCA-11, manufactured by Kyowa Interface Science Co., Ltd.). The contact angle was measured at 10 arbitrary locations on the treated surface, and the number average of the 10 measured values ​​was taken as the contact angle of water.

[0083] The same procedure was performed by replacing water with ethylene glycol (EG) or dimethylformamide (DMF) to obtain the contact angles for ethylene glycol and dimethylformamide. The results of the contact angle measurements are shown in Table 1.

[0084] [Evaluation Example 2: Chemical Composition of the Treated Surface of the Molded Article] The chemical composition of the treated surface of each molded article in the examples and comparative examples was determined using X-ray photoelectron spectroscopy (XPS). For analysis, the 1s spectrum was used for carbon, the 1s spectrum for nitrogen, and the 1s spectrum for silicon.

[0085] The XPS measurement conditions were as follows: • Instrument: Model 5400 (ULVAC-FI) • Excitation X-ray: MgKα • Element range: From Li (lithium) to U (uranium) • Analyzer: Electrostatic hemispherical analyzer

[0086] Table 1 shows the results of chemical composition measurements for the molded articles of the Examples and Comparative Examples. Figure 1 shows the C1s spectra for the molded articles of Example 1 and Comparative Example 1.

[0087] In the C1s spectrum shown in Figure 1, each peak was identified by performing peak separation using curve fitting processing with the analysis software attached to the instrument. Each peak identified by curve fitting separation was considered to be a "peak or peak shoulder" in its spectrum.

[0088] [Evaluation Example 3: Adhesion of the treated surface of the molded body] An ultraviolet-curable resin (EPICLON-UE-8215, manufactured by DIC Corporation) was applied to the treated surface of the molded bodies of the examples and comparative examples, and the resin was cured by irradiating it with ultraviolet light to form a cured resin layer. After attaching cellophane tape (registered trademark) to the cured resin layer, cuts were made in the tape and the cured resin layer to form a total of 100 squares in a 10x10 cross-cut pattern.

[0089] After making the cuts, the tape was vigorously pulled perpendicular to the treated surface of the molded body at one of the following points (1) to (3) to peel the tape from the sample: (1) Immediately after making cuts in the tape and cured resin layer (2) Immediately after making cuts in the tape and cured resin layer and exposing the sample to an environment of 65°C and 95% relative humidity for 500 hours (3) Immediately after making cuts in the tape and cured resin layer and exposing the sample to an environment of 85°C and 85% relative humidity for 500 hours

[0090] When the tape was peeled off the sample, it was determined for each cell whether the cured resin layer had peeled off from the molded body along with the tape. If one or more cells out of 100 showed peeling of the cured resin layer, the adhesion of that sample was evaluated as insufficient ("×"). If no cells out of 100 showed peeling of the cured resin layer, the adhesion of that sample was evaluated as high ("〇"). The evaluation results are shown in Table 2.

[0091]

[0092]

[0093] Note that the contact angle values ​​for water, etc., and the chemical composition values ​​for C, etc., shown in Table 1 are obtained by rounding the measured values ​​to one decimal place, while the ratio values ​​for EG / water, N / C, etc., shown in Table 1 are calculated from the measured values. Therefore, the ratios shown in Table 1 may not match the ratios calculated from the contact angle and chemical composition values ​​shown in Table 1.

[0094] [Results] As shown in Table 1, the molded articles of Examples 1 to 4 tended to show lower contact angles with water, ethylene glycol (EG), and dimethylformamide (DMF) compared with the molded articles of Comparative Examples 1 to 2. Compared with Comparative Example 2, which was manufactured in an atmosphere containing nitrogen atoms but not silicon atoms, the molded articles of Examples 1 to 4, which were manufactured in an atmosphere containing both nitrogen atoms and silicon atoms, showed a significantly lower contact angle with DMF.

[0095] Furthermore, as shown in Table 1, for Examples 1 to 4, the value obtained by dividing the contact angle of DMF by the contact angle of water (DMF / water) was 0.2 or less in all cases, while for Comparative Examples 1 to 2, the value obtained by dividing the contact angle of DMF by the contact angle of water was greater than 0.2 in all cases. Also, for Examples 1 to 4, the value obtained by dividing the contact angle of DMF by the contact angle of EG (DMF / EG) was 0.3 or less in all cases, while for Comparative Examples 1 to 2, the value obtained by dividing the contact angle of DMF by the contact angle of EG was greater than 0.4 in all cases.

[0096] As shown in Table 1, the molded articles of Examples 1 to 4 tended to have a lower carbon atom content (C), a higher nitrogen atom content (N), and a lower silicon atom content (Si) compared to the molded articles of Comparative Examples 1 to 2. Consequently, the molded articles of Examples 1 to 4 had higher N / C and Si / C ratios compared to the molded articles of Comparative Examples 1 to 2. Furthermore, compared to Comparative Example 2, which was manufactured in an atmosphere containing nitrogen atoms but not silicon atoms, the molded articles of Examples 1 to 4, which were manufactured in an atmosphere containing both nitrogen atoms and silicon atoms, tended to have a significantly higher nitrogen atom content (N). This suggests that silicon atoms in the atmosphere contribute in some way to the bonding of nitrogen atoms to the treated surface.

[0097] Furthermore, it is presumed that the presence of silicon atoms (Si) in the molded articles of Comparative Examples 1 and 2, which were manufactured in an atmosphere free of silicon atoms, is due to unavoidable contamination during the manufacturing process.

[0098] The spectrum of the molded article of Example 1, shown in Figure 1, exhibited peaks or peak shoulders around 286.7 eV and 288.4 eV, respectively. However, these peaks or peak shoulders were not observed in the spectrum of the molded article of Comparative Example 1. Of these peaks, the peak shoulder around 288.4 eV is thought to originate mainly from oxygen-related bonds such as O=C-O-. The peak intensity around 288.4 eV was weaker than the peak intensity of other peaks in the spectrum of Example 1.

[0099] On the other hand, the peak shoulder around 286.7 eV in Example 1 is thought to originate from C-N-Si bonds, C-O-Si bonds, or O-C-N-Si bonds. The peak intensity of this peak around 286.7 eV was weaker than the peak intensity of the peak around 288.4 eV in Example 1 that originates from oxygen-involved bonds such as O=C-O. From the above, it is suggested that the C-N-Si bond, which does not contain oxygen, is the main bond among C-N-Si bonds, C-O-Si bonds, and O-C-N-Si bonds in Example 1.

[0100] Furthermore, the peak shoulder around 284.7 eV in Example 1 is suggested to originate from the Si-C bond.

[0101] As shown in Table 2, the molded articles of Comparative Examples 1 and 2 showed high adhesion under condition (1), but insufficient adhesion under the high temperature and high humidity conditions of (2) and (3). In contrast, the molded articles of Examples 1 to 4 showed high adhesion under all conditions (1) to (3).

[0102] From the above results, it was found that a molded article made of polycarbonate resin for optical purposes has at least one first surface constituting at least a part of the surface of the molded article, which has a chemical composition different from the chemical composition of the interior of the molded article, and on at least one first surface, the contact angle of water is 40° to 65°, the contact angle of ethylene glycol is 20° to 40°, and the contact angle of dimethylformamide is 0° to 20°, and the molded article has a surface that exhibits high adhesion in a high temperature and high humidity environment without requiring the formation of an adhesive layer on the molded article.

Claims

1. A molded article made of polycarbonate resin for optical purposes, wherein the molded article has at least one first surface constituting at least a part of the surface of the molded article, the first surface having a chemical composition different from the chemical composition of the interior of the molded article, and the contact angle of water on the at least one first surface is 40° or more and 65° or less, the contact angle of ethylene glycol is 20° or more and 40° or less, and the contact angle of dimethylformamide is 0° or more and 20° or less.

2. The molded article according to claim 1, wherein, in the chemical composition of at least one first surface analyzed by X-ray photoelectron spectroscopy, the ratio of nitrogen atom content N to carbon atom content C (N / C) is 10 to 30 on an atomic percentage basis, and the ratio of silicon atom content Si to carbon atom content C (Si / C) is 5 to 40 on an atomic percentage basis.

3. The molded article according to claim 1 or 2, wherein the spectrum of at least one first plane, analyzed by X-ray photoelectron spectroscopy, has a peak or peak shoulder originating from a C-N-Si bond.

4. The molded article according to claim 1 or 2, wherein the spectrum of the at least one first surface analyzed by X-ray photoelectron spectroscopy has a peak or peak shoulder around 286.7 eV.

5. A laminate comprising a molded body according to claim 1 or 2, and a resin layer containing an ultraviolet-curing resin or a thermosetting resin, laminated on at least one first surface of the molded body.

6. A laminate comprising two or more molded bodies according to claim 1 or 2.

7. A method for manufacturing a molded article made of polycarbonate resin for optical purposes, comprising the step of treating at least a portion of the surface of a polycarbonate resin substrate that will be the base material of the molded article by bringing it into contact with a discharge plasma in an atmosphere containing a first gas comprising at least one organic compound having carbon atoms, nitrogen atoms, and silicon atoms in its chemical structure.

8. The method for producing a molded article according to claim 7, wherein the organic compound is at least one selected from the group consisting of polysilazanes and cyclosilazanes.

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