Compositions for optical materials, resin compositions, and resin molded articles

Abstract

The present invention provides an optical material composition that enables a large in-plane phase difference of an optical component, a resin composition containing the optical material composition, and a resin molded article thereof. [Solution] The optical material composition of the present invention contains a trehalose derivative. Preferably, such a trehalose derivative is one or more selected from the group consisting of trehalose benzoate, trehalose acetate, and trehalose naphthoate. The optical material composition of the present invention makes it possible to increase the in-plane phase difference of an optical member.

Description

Technical Field

[0001] The present invention relates to a composition for optical materials, a resin composition, a resin molded body, and a film.

Background Art

[0002] Various optical members such as optical films and polarizing plates are functional materials indispensable in the fields of electronic devices such as liquid crystal display devices and image display devices, and fields such as optical lenses, and are widely used. When the optical characteristics of an optical member are improved, the functions of a display device or the like can be made more high-performance. Therefore, a technique for further improving the optical performance in the field of optical members is extremely important.

[0003] It is known that an optical member can be manufactured, for example, by molding a highly transparent resin. Therefore, as a means for improving the optical performance of an optical member, it is effective to develop a resin capable of imparting excellent optical performance or to develop an additive capable of imparting excellent optical performance, and such studies are actively being conducted.

[0004] For example, Patent Document 1 proposes a material containing acicular or spindle-shaped inorganic particles having optical anisotropy and a transparent polymer. It is said that such a material can provide an optical film with a large in-plane retardation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the technology described in Patent Document 1 requires the use of inorganic particles, which presents a problem as it necessitates a process for dispersing the inorganic particles in the polymer. Furthermore, in recent years, there has been a desire to bring about further improvements in the optical properties of optical components, and there was room for improvement, for example, in increasing the in-plane phase difference of optical components.

[0007] The present invention has been made in view of the above, and aims to provide an optical material composition that enables a large in-plane phase difference of an optical component, a resin composition containing the optical material composition, and a resin molded article thereof. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to achieve the above objectives and, as a result, discovered that these objectives can be achieved by using a trehalose derivative as an essential component, thus completing the present invention.

[0009] In other words, the present invention encompasses, for example, the subject matter described in the following sections. Item 1 A composition for optical materials containing a trehalose derivative. Section 2 The optical material composition according to item 1, wherein the trehalose derivative is one or more selected from the group consisting of trehalose benzoate, trehalose acetate, and trehalose naphthoate. Section 3 A resin composition comprising the optical material composition described in item 1 or 2 and a resin having a cyclic skeleton. Section 4 The resin composition according to claim 3, wherein the resin having the cyclic skeleton is at least one selected from the group consisting of polycarbonate, polystyrene, and cellulose ester. Section 5 The resin composition according to item 4, wherein the cellulose ester is triacetylcellulose. Section 6 A resin molded article comprising a resin composition for optical materials as described in any one of items 3 to 5. Section 7 An optical material containing a resin molded article as described in item 6. [Effects of the Invention]

[0010] The optical material composition of the present invention can increase the in-plane phase difference of optical components and is suitable as an additive to optical components and the like. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. In this specification, the expressions "containing" and "including" include the concepts of "containing," "including," "substantially consisting of," and "consisting only of."

[0012] In the numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in one step can be arbitrarily combined with the upper or lower limit of a numerical range in another step. In the numerical ranges described in this specification, the upper or lower limit of a numerical range may be replaced with values ​​shown in the examples or values ​​that can be uniquely derived from the examples. Furthermore, in this specification, numbers connected by "~" mean a numerical range that includes the numbers before and after "~" as the lower and upper limits.

[0013] The optical material composition of the present invention contains a trehalose derivative as an essential component. When incorporated into an optical component containing a resin or the like, the in-plane phase difference of the optical component can be increased. In other words, the optical material composition of the present invention is suitable for use in adjusting the optical performance of an optical component and is suitable as an additive to an optical component.

[0014] Conventionally, in order to increase the in-plane phase difference of optical components such as optical films, it was necessary to stretch the film with a high stretching strength. However, by using the optical material composition of the present invention, it becomes possible to increase the in-plane phase difference of the film even at a lower stretching ratio than in the conventional method.

[0015] A trehalose derivative means a compound in which a hydrogen atom of a hydroxyl group of trehalose is substituted with another group. For example, a trehalose derivative is a compound formed by an esterification reaction (or esterification exchange reaction) between trehalose and a carboxylic acid or its ester compound. Therefore, a trehalose derivative is a compound having a structure in which a hydroxyl group in a trehalose molecule is replaced by a moiety derived from a carboxylic acid compound.

[0016] Examples of trehalose derivatives include trehalose benzoate, trehalose acetate, and trehalose naphthoate.

[0017] Among them, the trehalose derivative is preferably at least one selected from the group consisting of trehalose benzoate and trehalose acetate (that is, the trehalose derivative is preferably trehalose benzoate and / or trehalose acetate). In this case, the composition for an optical material of the present invention can make the in-plane retardation of an optical member larger.

[0018] Trehalose benzoate can have a benzoate moiety introduced into some or all of the plurality (up to 8) of hydroxyl groups derived from the trehalose molecule. That is, trehalose benzoate can exist as a monoester form, a diester form, a triester form, and the like. The trehalose benzoate contained in the composition for an optical material of the present invention can be any of these ester forms, and can contain not only one kind but also two or more kinds of ester forms. Also, the degree of esterification substitution of trehalose benzoate is not particularly limited. For example, the degree of esterification substitution of trehalose benzoate is 1 or more, preferably 1.1 or more, and may be 6 or more, or may be 7 or more. The degree of esterification substitution of trehalose benzoate is particularly preferably 7 to 8.

[0019] Trehalose acetate is a material in which acetate moieties can be introduced to some or all of the multiple hydroxyl groups (up to 8) derived from the trehalose molecule. In other words, trehalose acetate can exist as a monoester, diester, triester, etc. The trehalose acetate contained in the optical material composition of the present invention may be any of these esters, and may contain not just one but two or more esters. Furthermore, the degree of esterification substitution of trehalose acetate is not particularly limited. For example, the degree of esterification substitution of trehalose acetate is 1 or more, preferably 1.1 or more, and may also be 6 or more, or 7 or more. A degree of esterification substitution of trehalose acetate of 7 to 8 is particularly preferred. Therefore, a preferred example of trehalose acetate is trehalose octaacetate (i.e., an ester compound of trehalose and 8 acetic acids).

[0020] Trehalose naphthoate is a compound in which naphthoate moieties can be introduced to some or all of the multiple hydroxyl groups (up to 8) derived from the trehalose molecule. In other words, trehalose naphthoate can exist as a monoester, diester, triester, etc. The trehalose naphthoate contained in the optical material composition of the present invention may be any of these esters, and may contain not just one but two or more esters. Furthermore, the degree of esterification substitution of trehalose naphthoate is not particularly limited. The naphthoate moiety may be a 1-naphthyl group or a 2-naphthyl group. For example, the degree of esterification substitution of trehalose naphthoate is 1 or more, preferably 1.1 or more, and may also be 6 or more, or 7 or more. A degree of esterification substitution of trehalose naphthoate of 7 to 8 is particularly preferred.

[0021] The method for producing the trehalose derivative is not particularly limited, and for example, known production methods can be widely adopted. For example, a trehalose derivative can be synthesized by reacting trehalose with a carboxylic acid compound. Alternatively, a trehalose derivative can be synthesized by an ester exchange reaction between trehalose and a carboxylic acid ester compound.

[0022] When the trehalose derivative is trehalose benzoate, examples of the carboxylic acid compound include benzoic acid, and examples of the carboxylic acid ester compound include alkyl esters of benzoic acid. The alkyl group in these alkyl ester moieties is, for example, an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group.

[0023] Also, trehalose benzoate can be synthesized by reacting trehalose with benzoyl chloride.

[0024] When the trehalose derivative is trehalose acetate, examples of the carboxylic acid compound include acetic acid, and examples of the acetic acid ester compound include alkyl esters of acetic acid. The alkyl group in these alkyl ester moieties is, for example, an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group.

[0025] When the trehalose derivative is trehalose naphthoate, examples of the carboxylic acid compound include 1-naphthalenecarboxylic acid or 2-naphthalenecarboxylic acid, and examples of the carboxylic acid ester compound include, for example, alkyl esters of 1-naphthalenecarboxylic acid and alkyl esters of 2-naphthalenecarboxylic acid. The alkyl group in these alkyl ester moieties is, for example, an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms, and examples thereof include a methyl group.

[0026] Furthermore, trehalose naphthoate compounds can be synthesized by the reaction of trehalose with naphthoyl chloride. Specifically, naphthoyl chlorides include 1-naphthoyl chloride or 2-naphthoyl chloride.

[0027] The trehalose used in the method for producing trehalose derivatives may be synthesized by known methods, for example, or trehalose can be obtained from a commercially available product.

[0028] Trehalose derivatives can also be obtained from commercially available products.

[0029] The trehalose derivative contained in the optical material composition of the present invention may be one or more types.

[0030] The optical material composition of the present invention may contain other components besides the trehalose derivative, as long as the effects of the present invention are not inhibited. Examples of other components include pH adjusters, light stabilizers, antioxidants, preservatives, surfactants, fillers such as inorganic particles, flame retardants, pigments, colorants, fungicides, and lubricants. One or more of these additives may be included in the optical material composition of the present invention.

[0031] The optical material composition of the present invention may be in solid or liquid form. When the optical material composition of the present invention is in solid form, its shape is not particularly limited and examples include powder, granules, flakes, lumps, pellets, etc. When the optical material composition of the present invention is in liquid form, it may be a solution or a dispersion such as a slurry. The liquid optical material composition can be formed, for example, using a solvent.

[0032] The type of solvent is not particularly limited, and an appropriate solvent can be selected depending on the purpose. For example, the solvent can be appropriately selected depending on the purpose of dissolving or dispersing the trehalose derivative. The solvent may be water or various organic solvents. Examples of organic solvents include chlorinated hydrocarbons such as chloroform and 1,2-dichloroethane; ether compounds such as diethyl ether and tetrahydrofuran; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketone compounds such as acetone and methyl ethyl ketone; ester compounds such as vinyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and t-butanol; formamides such as N,N-dimethylformamide and N,N-dimethylacetamide; pyrrolidones such as 2-pyrrolidone and N-methylpyrrolidone; and dimethyl sulfoxides.

[0033] If the optical material composition of the present invention contains a solvent, its content is not particularly limited. Furthermore, if the optical material composition of the present invention is in solid form, it may be dissolved or dispersed in the solvent during use or storage.

[0034] In the optical material composition of the present invention, the content of the trehalose derivative is not particularly limited. For example, the content of the trehalose derivative relative to the total amount of the optical material composition of the present invention excluding the solvent can be 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The optical material composition of the present invention may consist only of the trehalose derivative.

[0035] The method for preparing the optical material composition of the present invention is not particularly limited and can be obtained by mixing a predetermined amount of trehalose derivative with other components as needed. The mixing method is not particularly limited and can be broadly employed using known mixing methods.

[0036] The optical material composition of the present invention, when incorporated into the optical component described below (an optical film such as a resin film), can increase the in-plane phase difference of the optical film. In particular, as described above, it is possible to increase the in-plane phase difference of the optical film even at a low stretching ratio. Therefore, the optical material composition of the present invention is suitable for use in adjusting the optical performance of optical components and is suitable as an additive to optical components. That is, the optical material composition of the present invention may also be an optical film composition.

[0037] Whether the in-plane phase difference of an optical component containing the optical material composition of the present invention is large can be determined from a graph plotting the relationship between the optical component (optical film) and its in-plane birefringence (ΔNxy). Specifically, a graph is created with the stretching strength when the optical component (optical film) is stretched on the X axis and the measured value of the in-plane birefringence (ΔNxy) of the optical component (optical film) on the Y axis, and the in-plane birefringence (ΔNxy) of the optical component (optical film) at each stretching strength is plotted on the graph. It is preferable to take at least two points (preferably three points) for each optical component (optical film). A straight line is drawn on the obtained plots based on the least squares method, and the slope of this line is taken as the in-plane phase difference of the optical film. That is, the larger the slope of the line, the larger the in-plane phase difference of the optical component (optical film) can be determined.

[0038] The method of using the optical material composition of the present invention is not particularly limited, and for example, it can be incorporated into various optical components by any appropriate method.

[0039] The content of the optical material composition of the present invention in an optical member is not particularly limited. For example, it is preferable that the trehalose derivative be contained in 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, particularly preferably 2 parts by mass or more, and also preferable that it be contained in 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less.

[0040] The method for incorporating the optical material composition of the present invention into an optical member is not particularly limited. For example, the optical material composition can be incorporated into an optical member by adding it at any stage in the manufacturing of the optical member. Alternatively, when molding an optical member to form a molded body, the optical material composition can be incorporated into the molded body by preparing a raw material by mixing the optical member with the optical material composition of the present invention in advance and then molding this raw material. By these methods, the optical material composition of the present invention can be incorporated into an optical member, thereby increasing the in-plane phase difference of the optical member.

[0041] When the optical material composition of the present invention is added to various optical components, the optical components may be in a solid state or in a liquid state such as a solution.

[0042] The type of optical component is not particularly limited; for example, various optical films can be cited, and resin films are preferred. Specific optical components can be broadly categorized into known resin films that can be used in the field of optics.

[0043] In particular, the resin forming the resin film is preferably a resin having an annular skeleton, as this allows for a larger in-plane phase difference with the optical material composition of the present invention.

[0044] A resin having a cyclic skeleton means that the polymer compounds constituting the resin have a cyclic skeleton within their molecules. A cyclic skeleton is, for example, a saturated or unsaturated cyclic group, such as an aromatic ring, a ring derived from a cycloalkane compound, a ring derived from a cycloalkene compound, or a ring derived from polysaccharides such as cellulose.

[0045] Specific examples of resins having a cyclic skeleton include polycarbonate resins, polystyrene resins, and cellulose esters. Other examples include polyester resins, acrylic resins, and polyolefin resins, which also have a cyclic skeleton. Polycarbonate resins include, for example, aromatic polycarbonate resins.

[0046] In particular, the resin having a cyclic skeleton is preferably at least one selected from the group consisting of polycarbonate, polystyrene, and cellulose ester. Resin films formed from these resins tend to have a particularly large in-plane phase difference when subjected to the optical material composition of the present invention, and moreover, it is possible to increase the in-plane phase difference of the film even at a low stretching ratio.

[0047] Examples of the cellulose esters mentioned above include monoacetylcellulose, diacetylcellulose, triacetylcellulose, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and polycaprolactone-grafted cellulose acetate.

[0048] Among these, triacetylcellulose is preferred as the cellulose ester. Resin films formed from triacetylcellulose tend to have a particularly large in-plane phase difference when subjected to the optical material composition of the present invention, and moreover, it is possible to increase the in-plane phase difference of the film even at a low stretching ratio.

[0049] Therefore, the resin having a cyclic skeleton is more preferably at least one selected from the group consisting of polycarbonate, polystyrene, and cellulose ester, and even more preferably at least one selected from the group consisting of polycarbonate, polystyrene, and triacetylcellulose.

[0050] The optical material composition of the present invention can be used in combination with various resins for forming the resin film described above. For example, the optical material composition of the present invention can be combined with the resin having the annular skeleton described above to form a resin composition. A resin molded article can also be obtained using the resin composition.

[0051] By including the optical material composition of the present invention, such a resin composition can form a resin film with a large in-plane phase difference, and the resulting resin film can have a high in-plane phase difference even at a low stretch ratio.

[0052] The shape of the resin contained in the resin composition is not particularly limited, and may be in the form of powder, pellets, lumps, fibers, etc. The method for obtaining a resin molded article (e.g., a resin film) from the resin composition is also not particularly limited, and known resin film molding methods can be widely used in the present invention.

[0053] The proportion of the optical material composition and resin of the present invention contained in the resin composition is not particularly limited. For example, it is preferable that the trehalose derivative be present in an amount of 0.1 parts by mass or more per 100 parts by mass of resin, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, particularly preferably 2 parts by mass or more, and also preferable that it be present in an amount of 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less.

[0054] The method for preparing the resin composition is not particularly limited; for example, the resin composition can be prepared by mixing a predetermined resin with the optical material composition of the present invention.

[0055] In the resin composition, the total content of the resin and the trehalose derivative is not particularly limited. For example, the content of the trehalose derivative relative to the total amount of the optical material composition of the present invention, excluding the solvent, can be 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The resin composition may consist only of the trehalose derivative and the resin.

[0056] In specifying the inventions contained herein, the components (properties, structures, functions, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure encompasses all subject matter consisting of any combination of the combinatable components described herein. [Examples]

[0057] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0058] (Manufacturing example 1; Trehalose benzoate) Trehalose benzoate was prepared by a known method. Specifically, 34.2 parts by mass of trehalose (manufactured by Nagase Vita) and 70 parts by mass of water were charged into a 1 L five-necked flask equipped with a stirring rod, thermometer, cooling condenser, dropping funnel, and pH electrode connected to a pH meter, and dissolved. Then, while cooling to below 10°C in a water bath, 100 parts by mass of cyclohexanone containing 75.0 parts by mass of benzoyl chloride was gradually added. Subsequently, while maintaining a temperature below 20°C, 48.5 parts by mass of a 48% caustic soda aqueous solution was added via a dropping funnel at a rate that maintained the pH at 10-11. After removing the water bath, stirring was continued at room temperature (20-30°C) for 1 hour to complete the reaction. A small amount of sodium carbonate was then added and heated to convert the trace amounts of remaining benzoyl chloride into sodium benzoate. After standing for about 30 minutes, the aqueous phase was separated and removed. 70 parts by mass of water were added, the mixture was heated to 40-50°C in a water bath, stirred for 30 minutes, and then allowed to stand for about 30 minutes to separate and remove the aqueous phase. This procedure was repeated two more times (total number of water washes: 3), the mixture was heated to 120°C, and the solvent was removed under reduced pressure to obtain the trehalose benzoate with a degree of esterification substitution of 7-8.

[0059] (Manufacturing example 2; Trehalose octaacetate) A 500 mL separable flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen gas inlet tube was mounted on a heating oil bath. Using this separable flask, 50 g (0.15 mol) of trehalose, 570 g (7.2 mol) of pyridine, and 120 g (1.18 mol) of acetic anhydride were mixed and reacted at 70°C for 2 hours while bubbling nitrogen gas at a flow rate of 10 mL / min. Pyridine, unreacted acetic anhydride, and by-product acetic acid were removed by distillation under reduced pressure. 220 g of methanol was added to the resulting residue and mixed, and crystals were precipitated by standing at -5°C for 18 hours. This solution was filtered to remove the precipitated crystals, washed with 30 g of methanol at -5°C, and further dried under reduced pressure at 45°C for 8 hours to obtain trehalose octaacetate.

[0060] (Manufacturing example 3; Trehalose 2-naphthoate) Trehalose naphthoate was prepared by a known method. Specifically, 34.2 parts by mass of trehalose (manufactured by Nagase Vita) and 70 parts by mass of water were charged into a 1 L five-necked flask equipped with a stirring rod, thermometer, cooling condenser, dropping funnel, and pH electrode connected to a pH meter, and dissolved. Then, while cooling to below 10°C in a water bath, 100 parts by mass of cyclohexanone containing 75.0 parts by mass of 2-naphthoyl chloride was gradually added. Subsequently, while maintaining a temperature below 20°C, 48.5 parts by mass of a 48% caustic soda aqueous solution was added via a dropping funnel at a rate that maintained the pH at 10-11. After removing the water bath, stirring was continued at room temperature (20-30°C) for 1 hour to complete the reaction. A small amount of sodium carbonate was then added and heated to convert the trace amounts of remaining 2-naphthoyl chloride into sodium 2-naphthoate. After standing for about 30 minutes, the aqueous phase was separated and removed. 70 parts by mass of water were added, the mixture was heated to 40-50°C in a water bath, stirred for 30 minutes, and then allowed to stand for about 30 minutes to separate and remove the aqueous phase. This procedure was repeated two more times (total number of water washes: 3), the mixture was heated to 120°C, and the solvent was removed under reduced pressure to obtain trehalose 2-naphthoate with a degree of esterification substitution of 7-8.

[0061] (Manufacturing example 4; sucrose benzoate) Sucrose benzoate was obtained using the same method as in Production Example 1, except that trehalose was replaced with sucrose.

[0062] (Manufacturing example 5; Sucrose octaacetate) Sucrose octaacetate was obtained using the same method as in Production Example 2, except that trehalose was replaced with sucrose.

[0063] (Manufacturing example 6; sucrose naphthoate) Sucrose naphthoate was obtained using the same method as in Production Example 3, except that trehalose was replaced with sucrose.

[0064] (Example 1) The trehalose benzoate (hereinafter sometimes abbreviated as "TB") obtained in Production Example 1 was obtained as an optical material composition.

[0065] (Example 2) The trehalose octaacetate (hereinafter sometimes abbreviated as "TOA") obtained in Production Example 2 was obtained as an optical material composition.

[0066] (Example 3) The trehalose 2-naphthoate (hereinafter sometimes abbreviated as "TN") obtained in Production Example 3 was obtained as an optical material composition.

[0067] (Comparative Example 1) The sucrose benzoate (hereinafter sometimes abbreviated as "SB") obtained in Production Example 4 was obtained as an optical material composition.

[0068] (Comparative Example 2) The sucrose octaacetate (hereinafter sometimes abbreviated as "SOA") obtained in Production Example 5 was obtained as an optical material composition.

[0069] (Comparative Example 3) The sucrose naphthoate (hereinafter sometimes abbreviated as "SN") obtained in Production Example 6 was obtained as an optical material composition.

[0070] (Evaluation method) [In-plane phase difference measurement] Preparation of resin film A resin film for measuring in-plane phase difference was prepared using the following procedure. One of the following resins was used: PC, PS, TAC, or PMMA. PC: Polycarbonate resin (Toughlon® A2200: Manufactured by Idemitsu Kosan Co., Ltd.) PS: Polystyrene resin (PSJ-Polystyrene GPPS G9305: Manufactured by PS Japan Co., Ltd.) TAC: Cellulose ester resin (LT-105: Manufactured by Daicel Corporation) PMMA: Polymethyl methacrylate resin (Acrypet® SV001: Manufactured by Mitsubishi Chemical Corporation)

[0071] A resin composition was prepared by mixing 5 parts by mass of the optical material composition obtained in each example and comparative example with 100 parts by mass of the resin. This resin composition was dissolved in dichloromethane as a solvent to obtain a solution with a concentration of 100 g / L. A resin film with a thickness of 40 μm was obtained by a casting method using this solution.

[0072] ≪In-plane phase difference measurement≫ The resin film obtained as described above was cut into 40mm x 60mm pieces, and stretched films were prepared by stretching them at various stretching strengths (e.g., 2x stretching) using a uniaxial stretcher. The in-plane refractive index ΔNxy of each stretched film was measured. The stretching temperature was set to 140-160°C for PC, 110-120°C for PS, 210-230°C for TAC, and 80-100°C for PMMA. The in-plane refractive index of the stretched film was measured using a "KOBRA-WR" manufactured by Oji Instruments Co., Ltd., under conditions of 23°C and 40%RH. The in-plane refractive index of the stretched film was measured after converting it to a thickness of 40μm. The in-plane refractive index of the stretched film obtained at each stretching strength was plotted on a stretching strength-ΔNxy graph (i.e., a graph where the X axis is the stretching strength of the resin film (stretched film) and the Y axis is the in-plane birefringence (ΔNxy)). A straight line was drawn using the least squares method, and the magnitude of the in-plane phase difference of the resin film was determined from the slope of this line.

[0073] (Evaluation results) Tables 1, 2, and 3 show the slope of the straight line in the tensile strength-ΔNxy graph for resin films (PC, PS, TAC, or PMMA films) containing the optical material compositions obtained in each example and comparative example, respectively. Table 4 contains the data obtained for plotting the aforementioned tensile strength-ΔNxy graph for each film. For clarification, in the matrix in Table 4, for example, each value in the PC-Comparative Example 1 column represents the tensile strength value and the ΔNxy value at that tensile strength when the PC film (polycarbonate resin film) containing the optical material composition of Comparative Example 1 is stretched.

[0074] The results in Tables 1-3 show that the optical material composition consisting of a trehalose derivative (Example) can increase the in-plane phase difference of various resin films compared to the Comparative Example. In particular, when the resin film is formed of a resin having a cyclic skeleton (polycarbonate, polystyrene, cellulose ester), the optical material composition of the Example can significantly increase the in-plane phase difference compared to the optical material composition of the Comparative Example.

[0075] [Table 1]

[0076] [Table 2]

[0077] [Table 3]

[0078] [Table 4]

Claims

1. A composition for optical materials containing a trehalose derivative.

2. The optical material composition according to claim 1, wherein the trehalose derivative is one or more selected from the group consisting of trehalose benzoate, trehalose acetate, and trehalose naphthoate.

3. A resin composition comprising the optical material composition according to claim 1 or 2 and a resin having a cyclic skeleton.

4. The resin composition according to claim 3, wherein the resin having a cyclic skeleton is at least one selected from the group consisting of polycarbonate, polystyrene, and cellulose ester.

5. The resin composition according to claim 4, wherein the cellulose ester is triacetylcellulose.

6. A resin molded article comprising the resin composition described in claim 3.

7. An optical material comprising a resin molded article as described in claim 6.

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