KR20160027935A - Optical resin material, method for preparing said optical resin material, optical resin member formed of said material and polarizing plate comprising said member - Google Patents

Abstract

The purpose of the present invention is to provide a technique capable of stably and surely obtaining resin products, such as a resin material which is useful for an optical use and has very small or desired orientation birefringence, and an optical film whose temperature dependency of main birefringence influencing optical characteristics is reduced. In addition, the present invention relates to an optical resin material, a method for preparing the optical resin, a film-shaped optical resin member formed of said material, and a polarizing plate comprising same member. The optical resin material comprises a composite component system in which the component number z is 2 or greater, wherein the component number is defined in a condition where the original number of a (co)polymer, x (x>=1), is counted to be included in the component number. The intrinsic birefringence, Δn^0, is respectively measured at each individual temperature under conditions where the temperature of a film, which is a uniaxially stretched film made of the composite-component system, is controlled within 15-70°C by stages. The absolute value of temperature coefficient of intrinsic birefringence at 15-70°C, which is obtained as a variation of the intrinsic birefringence per 1°C from a result of the measurement is in the range of 1.0 X 10^-5 (°C^-1) or less. Further, the temperature dependency of main birefringence is reduced.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical resin material, a method for producing the optical resin material, an optical resin member made of the above material, and a polarizing plate made of the above-mentioned material. BACKGROUND OF THE INVENTION 1. Field of the Invention MEMBER}

The present invention relates to an optical resin material in which the temperature dependence of the intrinsic birefringence of a polymer is suppressed (that is, the intrinsic birefringence is not changed by the measurement temperature), the intrinsic birefringence is adjusted to almost zero or a desired value, An optical resin member made of these materials, and a polarizing plate made of such a member.

In recent years, the diffusion and development of liquid crystal displays have been remarkable, and it is no exaggeration to say that they are used in all products of electronic apparatuses. In addition, in the case of a desktop PC monitor or a liquid crystal TV, the enlargement is progressing, and many products of 40 inches or more are coming out. A liquid crystal panel generally used in a liquid crystal display has a structure in which a liquid crystal display cell in which a liquid crystal component is sandwiched between two glass substrates and a polarizing plate are laminated and a polarizing film , An optical film capable of exhibiting various functions such as a retardation film and an antireflection film, and the like. As the material of such an optical member, a light-transmitting resin called " optical resin " or " optical polymer " The optical member made of these resin materials is not limited to the liquid crystal display described above, but is used in various optical related apparatuses. For example, in addition to the above, it is also possible to use a lens having excellent optical properties such as a lens in a signal reading lens system of an optical disk, a Fresnel lens for a projection screen, a plastic lens such as a lenticular lens, And is also used as a required functional member.

Here, the resin film is produced by, for example, melt extrusion molding, stretching or the like from the viewpoint of productivity thereof. In various optical films and plastic lenses made of the optical polymer thus produced, the polymer molecules are oriented in any one direction for various reasons and are not in an ideal amorphous state, and the refractive index differs depending on the polarization direction of the incident light , That is, birefringence occurs. There are several known birefringence of polymers. What is important in a transparent polymer used for an optical film for a liquid crystal display, a plastic lens, and the like, which is used in various optical related devices described above, Oriented birefringence " and " photoelastic birefringence ".

On the other hand, there is known a method of substantially eliminating one of orientation birefringence and photoelastic birefringence by selecting an additive to a light-transmitting polymer and its concentration, or by selecting a combination of copolymerization and a composition ratio. In the technique, the attenuation of the other side was insufficient. Under such circumstances, the inventors of the present application propose a technique of simultaneously attenuating and substantially eliminating the orientation birefringence and the photoelastic birefringence of an optical resin material, and to provide a method of producing an optical resin (optical polymer) having both a small orientation birefringence and a small photoelastic birefringence (Optical element, optical component, etc.) of the above resin (see Patent Document 1).

Concretely, it is preferable that the combination of the components of the composite component system and the component ratio (composition ratio) of the optical component are such that the optical material has both orientation birefringence and photoelastic birefringence And simultaneously, the optical birefringence and the photoelastic birefringence are both obtained. Thus, a very small optical resin is obtained by both the orientation birefringence and the photoelastic birefringence. As a result, it is possible to improve the problem of light leakage due to birefringence, and by using the obtained optical resin, it is possible to prevent the occurrence of "color uneven phenomenon", "light leakage" And the like.

Japanese Patent Publication No. 4624845

However, as a result of intensive studies by the present inventors, it has been found that, in the above-mentioned prior arts, in a composite component system of three or more components including a copolymer of two or more systems, both optical birefringence and photoelastic birefringence are extremely small. The optical characteristics of the film are at room temperature, and they have newly recognized that there are the following technical problems in actual use environments. Specifically, in the above-mentioned prior art, a complex component system is determined by using the intrinsic birefringence of each homopolymer corresponding to each monomer constituting each component of the copolymer. In this case, the intrinsic birefringence is measured at room temperature (room temperature) The inventors of the present invention have found that the intrinsic birefringence is temperature-dependent, and that the tendency becomes larger with temperature rise. The inventors of the present invention have thus come to realize that this point needs to be taken into consideration. That is, as described above, the optical film is used in various optical-related devices. For example, a cellular phone or a PC is not always used at a room temperature, but is used in various temperature environments such as extremely cold or hot Especially, since these devices generate heat during operation, various heat dissipation and cooling means are conceivable. However, the temperature of the optical film may locally increase. On the other hand, it is extremely useful in practical use if a product having an influence on the optical characteristics and considering the temperature dependence of the intrinsic birefringence newly discovered by the present inventors is obtained.

Accordingly, an object of the present invention is to provide a resin product such as an optical film which can be reliably and reliably obtained by considering the temperature dependence of intrinsic birefringence (i.e., orientation birefringence inherent to a polymer) A technology capable of reliably and reliably obtaining a resin material useful for optical applications in which the intrinsic birefringence is extremely small and the temperature dependency thereof is reduced. When such a technology is provided, it is possible to prevent the occurrence of "color unevenness", "light leakage" or "color change depending on the viewing angle" which occur in the screen due to the optical film used in various optical- Can be reliably suppressed, and a stable high performance liquid crystal display or the like can be designed. Another object of the present invention is to appropriately use the above-described technique to stably and surely adjust a resin material useful for optical applications in which the intrinsic birefringence is set to a desired value after considering the temperature dependency, and furthermore, For example, a polymer that is easy to exhibit orientation birefringence. When such a technique is provided, for example, in the case of a phase difference film of a liquid crystal display, it is necessary to adjust the orientation birefringence and the thickness so as to obtain a desired retardation by stretching the film in the manufacturing process. It is possible to obtain a film of desired orientation birefringence at a magnification, and thus a great merit in manufacturing can be obtained.

As a result of intensive investigations, the inventors of the present invention have found that an optical resin material having a composite component system of two or more components including a copolymer system of binary system or more and a (co) (I. E., Intrinsic birefringence inherent to the polymer), which is newly discovered by the inventors of the present invention at the time of designing the combination of the kinds of the monomer components constituting the complex component system and the composition ratios thereof (composition ratio) The present inventors have found a method for reducing the temperature dependency in the above-mentioned temperature range.

The above object is achieved by the following invention. That is, the present invention relates to an optical resin comprising a composite component system having a component number z of 2 or more, which is defined under the condition that the number of elements x (x? 1) of the (co) polymer is included in the component number and is counted. As the material, the complex component system may be composed of only a copolymer having a raw number x of 2 or more, or a copolymer having a raw number x of 1 or a raw number x of 2 or more and a copolymer having an anisotropy of polarizability and at least Wherein the combination of components constituting the complex component system is constituted by one kind of low molecular organic compound and the combination of the constituent components of the low molecular weight component and the low molecular weight component of the homopolymer corresponding to each monomer component forming the copolymer or polymer, At least one of the intrinsic birefringence temperature coefficients commonly exhibited by the organic compound in each of the homopolymers is selected to have a different sign from that of the other, Component ratio of the respective components constituting the component sum, using a different code relationship regarding the number of unique birefringence thermometer, provides an optical resin material being selected so that the intrinsic birefringence temperature dependent offset.

As a preferable form of the optical resin material, the uniaxially stretched film made of the above-mentioned composite component system is used to adjust the intrinsic birefringence? N ⁰ at the individual temperature in a state in which the temperature of the film is controlled in the range of 15 to 70 ° C stepwise And the absolute value of the intrinsic birefringence temperature coefficient d? N ⁰ / dT at 15 占 폚 to 70 占 폚, which is obtained as the change amount of the intrinsic birefringence per 1 占 폚, is within a range of 1.0 占^10-5 (占 폚 ^-1 ) , And the temperature dependence of the intrinsic birefringence is reduced.

Further, the present invention is an optical resin material comprising a composite component system in which the number of components z is 3 or more, which is defined under the condition that the number of components x (x? 2) of the copolymer is included in the component number and counted, x is not less than 3, or a copolymer having a number of raw x of 2 or more and at least one kind of low molecular weight organic compound having anisotropy of polarizability and capable of orienting in the polymer, The combinations of the components include the respective signs of the intrinsic birefringence of each homopolymer corresponding to each monomer component forming the copolymer and the sign of the orientation birefringence common to the respective homopolymers At least one of the homopolymers has a different sign from the other, and the intrinsic birefringence temperature coefficient of each of the homopolymers, Wherein at least one of the intrinsic birefringence temperature coefficients common to the respective homopolymers of the low-molecular organic compound is selected to have a different sign from that of the other, and the component ratios of the components constituting the complex compound system are different from each other Wherein the optical birefringence and the intrinsic birefringence temperature dependence exhibited by the optical resin are selected so as to be simultaneously canceled by using a different sign relation with respect to the refractive index and the intrinsic birefringence temperature coefficient of the optical resin.

Preferred examples of the optical resin material include those described below. The intrinsic birefringence? N ⁰ at each temperature is measured by using a uniaxially stretched film made of the aforementioned composite component in a state where the temperature of the film is controlled in the range of 15 to 70 ° C, The absolute value of the intrinsic birefringence temperature coefficient d? N ⁰ / dT at 15 ° C to 70 ° C, which is obtained as the change amount of the intrinsic birefringence per ° C, is in the range of 1.0 × 10 ^-5 (° C ^-1 ) or less and the temperature dependence of the intrinsic birefringence is reduced Having; An optical resin material comprising a copolymer formed by copolymerizing three or more kinds of monomer components, wherein the combination of the above three or more monomer components and the composition ratio of these monomer components are each a homopolymer corresponding to each monomer component The intrinsic birefringence Δn ⁰ of the uniaxially stretched film at 25 ° C. and the temperature of the film are controlled stepwise in the range of 15 to 70 ° C. and the intrinsic birefringence Δn ⁰ at each temperature is measured respectively, D? N ⁰ / dT obtained as an amount of change in intrinsic birefringence per 1 ° C, and the absolute birefringence? N ⁰ at 25 ° C measured using a uniaxially stretched film made of the copolymer is And the absolute value of the intrinsic birefringence at 25 DEG C is adjusted to be almost zero, that is, 3.0 x 10 < ^-3 > or less, And the absolute value of the intrinsic birefringence temperature coefficient d? N ⁰ / dT at 15 ° C to 70 ° C is adjusted to be 1.0 × 10 ^-5 (° C ^-1 ) or less, The temperature dependency is reduced.

Further, the present invention is, as another embodiment, a method for producing any one of the optical resin materials described above, wherein the kind of the monomer component of the complex component system selected as the raw material is determined and the composition ratio of the selected two or more monomer components is determined And the uniaxially stretched film composed of each homopolymer corresponding to each monomer component in the raw material adjusting step is subjected to a film forming step in which the temperature of the film is controlled stepwise in the range of 15 to 70 DEG C, And the intrinsic birefringence temperature coefficient d? N ⁰ / dT, which is the change amount of the intrinsic birefringence per 1 ° C, is calculated from the obtained measurement results, and the intrinsic birefringence temperature coefficient d? N ⁰ / create a relationship graph between the intrinsic birefringence Δn ^0, and from the relationship graph, and the inherent birefringence Δn ⁰ measured at 25 ℃ the unique In combination with a composition that can birefringence thermometer dΔn ⁰ / dT is zero together be present, or the intrinsic birefringence, and the temperature coefficient dΔn ⁰ / dT is zero, and also, the value of not less than the absolute value of the intrinsic birefringence at 25 ℃ 0.01 hope And the intrinsic birefringence Δn ⁰ measured at 25 ° C. inherent to the copolymer obtained by copolymerizing the selected monomer components is determined to be zero or a specific value, Assuming that the absolute value of the intrinsic birefringence measured at 25 ° C is a desired value of 0.01 or more and that the intrinsic birefringence temperature coefficient d? N ⁰ / dT is zero, the mass ratio of each monomer component is calculated, Determining the composition ratio of the components, using the selected and determined kind of monomer component, and adding the monomer component to the determined composition ratio It provides a method for producing an optical resin material by copolymerizing the monomers, characterized in that for synthesis of the copolymer.

In a preferred embodiment of the method for producing an optical resin material, when determining the composition ratio of the monomer component to be combined, the monomer component is N (where N is an integer of 3 or more), and the monomer component is copolymerized with the Assuming that the intrinsic birefringence and the intrinsic birefringence thermometer numbers together become 0 (zero) or the desired value, the mass fraction of each monomer is calculated using the following simultaneous equations and the composition ratio of the monomers constituting the copolymer is determined ≪ / RTI >

[In the formula (i), Δn ⁰ ₁ is, first indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _2, the second indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _N is the N-th homopolymer Lt; / RTI > In the above formula _{^{(ii), dΔn 0 1 /}} dT , the first represents the number of intrinsic birefringence thermometer of the second homopolymer, dΔn ⁰ ₂ / dT, the second of the second homopolymer intrinsic birefringence represents the temperature coefficient, dΔn ⁰ _N / dT represents the intrinsic birefringence temperature coefficient of the Nth homopolymer. In the formula (iii), W ₁ , W ₂ and W _N represent the mass fraction (%) of the first, second and Nth monomers, respectively.

Further, the present invention provides a film-like optical resin member which is formed by forming any one of the above-mentioned optical resin materials in a film form and is adjusted so as not to cause temperature dependency exhibited by the intrinsic birefringence. A preferred form thereof is a film-shaped optical resin member formed by forming a pressure-sensitive adhesive layer on at least one surface of the film. In addition, the present invention provides a polarizing plate characterized by being made of these film-shaped optical resin members.

Here, of the intrinsic birefringence Δn ⁰ "nearly zero" in the present specification, close to zero or zero, and means that the numerical value that can be considered to be almost zero, numerically surface, its absolute value is 3.0 × 10 represents ^{- 3} or less, and more preferably 1.0 x 10 < ^-3 > or less. Further, "the temperature dependency of the intrinsic birefringence is reduced" means that the intrinsic birefringence at the individual temperature is measured individually in the state where the temperature of the uniaxially stretched film is controlled in the range of 15 to 70 ° C D? N ⁰ / dT ", which is the amount of change in the intrinsic birefringence per 1 ° C, is calculated from the measurement results, the absolute value of the intrinsic birefringence temperature coefficient is within 1.0 × 10 ^-5 (° C. ^-1 ) .

According to the present invention, it is possible to provide a resin which is useful for optical applications in which the orientation birefringence is extremely small, for example, and which can reliably and reliably obtain a resin product such as an optical film in consideration of temperature dependency of intrinsic birefringence, Technology is provided. As a result, there is a problem of "uneven phenomenon", "light leakage" and "color depending on the angle of observation" which occur in the screen due to the optical film used in various optical related apparatuses used in various temperature ranges, Change " and the like can be reliably suppressed, and a stable high-performance liquid crystal display can be designed. Further, according to the present invention, there is provided a technique which makes it possible to adjust the orientation birefringence to a desired value after consideration of temperature dependency, and to synthesize a polymer which is easy to exhibit orientation birefringence. For example, in the case of a retardation film of a liquid crystal display, it is necessary to adjust the orientation birefringence and the thickness so as to obtain a desired retardation by stretching the film in a manufacturing process. In this case, desired orientation birefringence And a resin material useful for optical applications in which the temperature dependence is reduced can be stably and reliably prepared. Thus, an extremely industrially useful effect can be obtained. Further, by using an optical resin member formed by forming a pressure-sensitive adhesive layer on at least one surface of a film, which is further processed by using a pressure-sensitive adhesive to the film-shaped optical resin material provided by the present invention, Quot; color uneven phenomenon ", " light leakage ", " color change depending on the observation angle ", and the like can be controlled.

1 is a graph showing the intrinsic birefringence Δn ⁰ at 25 ° C. measured using a film formed by each homopolymer corresponding to four kinds of monomers and the intrinsic birefringence Δn ⁰ measured at 25 ° C., birefringence coefficient dΔn ⁰ / dT and, in that case, as the copolymer (copolymer) which is a combination of these monomers, the monomer of the three is Δn ⁰ and dΔn ⁰ / dT of the copolymer that is with zero Are two kinds of combinations.
FIG. 2 shows the orientation of a film formed of a polymer having intrinsic birefringence at almost zero at 25 ° C formed of a ternary copolymer P (MMA / TFEMA / BzMA = 52.0 / 42.0 / 6.0) obtained by copolymerizing three kinds of monomers And shows the temperature dependency of the birefringence? N _or . MMA is the abbreviation of methyl methacrylate, TFEMA is the abbreviation of 2,2,2-trifluoroethyl methacrylate, and BzMA is the abbreviation of benzyl methacrylate.
Fig. 3 is a graph showing the temperature dependence of the intrinsic birefringence? N ⁰ of a film formed by polymerizing three kinds of monomers shown in Fig. 2 and having a substantially zero intrinsic birefringence at 25 ° C.
4 is a graph showing the temperature dependency of the intrinsic birefringence? N ⁰ of a film formed from a two-component copolymer P (MMA / MeMI = 82/18) obtained by copolymerizing two kinds of monomers. MeMI is the abbreviation of methylmaleimide.
5 is a graph showing the relationship between (a) orientation birefringence DELTA n (n) in each of the three-component copolymer P (MMA / PhMA / BzMA = 39/23/38) prepared in Example 1 and MMA homopolymer PMMA and a graph showing a relation _or the orientation help, (b) is a diagram showing the temperature dependence of the intrinsic birefringence Δn ^0.
6 is a graph showing the relationship between the intrinsic birefringence Δn (MMA / PhMA / EMI = 29/54/17) of the three-component copolymer P (MMA / PhMA / EMI = 29/54/17) prepared in Example 3 and the homopolymer of MMA ^{0 &lt}; / RTI > PhMA is the abbreviation of phenyl methacrylate, and EMI is the abbreviation of ethyl maleimide.
7 is a conceptual diagram of a temperature control device of a sample film used for examining temperature dependency of intrinsic birefringence.
8 is a graph showing the relationship between the intrinsic birefringence Δn ⁰ at 25 ° C. measured using a film formed by each of the homopolymers corresponding to three kinds of monomers and the photoelastic coefficient C obtained from the photoelastic birefringence measured using the film And the composition of the copolymer (copolymer) wherein Δn ⁰ and C together are 0 (zero) is present as a combination of monomers thereof.

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments for carrying out the invention.

First, each term used in the present invention will be described. The " orientation birefringence " is a birefringence expressed by the orientation of the main chain of a polymer in the form of a chain (polymer chain) in general. For example, the orientation birefringence is a production process by extrusion molding and stretching of a polymer film, This occurs in the manufacturing process of various polymer optical elements and parts. That is, the polymer chain oriented by stress in the molding process of these materials can not be alleviated during cooling and solidification , and the main chain is oriented in the film / optical device, which causes orientation birefringence.

The "orientation birefringence" is generally determined by heating the polymer film to be measured at a temperature not lower than the glass transition temperature, uniaxially stretching in a softened state, and subsequently cooling and solidifying the polymer film, followed by measurement with a commercially available birefringence measuring device at room temperature . At this time, as shown in the formula (1), a linearly polarized light having a polarization plane (a plane including the traveling direction of light and a direction of electric field oscillation) in the parallel direction and the orthogonal direction to the uniaxial stretching direction, of the difference between the refractive index n _p of the parallel direction and the orthogonal direction of the refractive index n _d (n _p -n _d), it is defined as the orientation birefringence Δn _or.

Then, the Δn _or telling that "the birefringence is caused" when non-zero, it is referred to the value referred to as "double refraction". The case where? _Nor is a positive value, that is, a case where the refractive index in the parallel direction is large is referred to as "positive birefringence", and when? _Nor is a negative value, that is, Is referred to as " negative (-) oriented birefringence ". Further, it is known that randomly copolymerizing a positive orientation birefringent monomer and a negative orientation birefringent monomer at an appropriate ratio makes it possible to achieve zero birefringence at a molecular level, and has been put to practical use as a polymer for a pickup lens of an optical disk.

In the above case, when the linearly polarized light enters the stretched film, the light passing therethrough is decomposed into two linearly polarized lights orthogonal to each other, and a phase difference (retardation) occurs due to birefringence. The retardation Re is in the relationship as shown in the following formula (2) with the orientation birefringence and thickness d of the film.

In a general measuring apparatus, the above retardation can be measured in many cases. This measure means that a by dividing the result of the retardation obtained with the film thickness d, birefringence Δn _or orientation, be determined by calculation.

Here, the orientation birefringence Δn _or is the above-described degree of orientation f, intrinsic birefringence may be associated relationship as ⁰ and Δn, equation (3). That is, the extent to which the polymer main chain is oriented is referred to as orientation degree, and is represented by "f", and "f" has a value between 0 and 1.

f = 1 means that the polymer molecules are completely constant (completely stretched), and f = 0 means that the polymer molecules are completely random. "Intrinsic birefringence" Δn ^0, the degree of orientation f = corresponds to the orientation birefringence of each of the case of 1 and a unique properties according to the type of polymer. The orientation degree f can be measured by an infrared dichroic method (two-color method) or the like. Thus, by measuring the degree of orientation f, and orientation birefringence Δn _or, respectively, it can be obtained "intrinsic birefringence Δn ^0" in the measurement target polymer film. As described above, the orientation birefringence is a value attributed to the fact that the polymer can not be alleviated during cooling and solidification after melting the polymer and exists in a state in which the main chain is oriented in the film / optical device. Therefore, Various studies have been made on the idea that selection of a material that does not cause orientation birefringence is possible by examining the intrinsic value of the "intrinsic birefringence" in detail in optical applications using polarized light.

In addition to the orientation birefringence described above, in optical elements and parts formed by a polymer, the volume shrinkage generally occurs when the glass substrate is cooled to a temperature lower than the glass transition temperature (Tg) There is a photoelastic birefringence which is caused by external stress or the like. This photoelastic coefficient is an inherent property depending on the type of polymer. As described above, the inventors of the present invention have found that, even if an optical film is produced by a conventional production method of an optical film such as melt extrusion, in which birefringence is likely to occur, the above-mentioned "orientation birefringence" and "photoelastic birefringence" And a method for obtaining an optical film having no light leakage is proposed.

Optical devices and parts made of industrially produced polymers are generally produced by a method such as extrusion molding, stretching, injection molding, etc., in which "the polymer is heated to a glass transition temperature or higher, molded in a molten state, In many cases. Therefore, as described above, orientation birefringence easily occurs, and when stress is applied to the obtained optical element at a glass transition temperature or lower, photoelastic birefringence is likely to occur. Such birefringence is an optical film of a liquid crystal display for which it is required to maintain the polarization state of incident polarized light, and in various lenses, etc., the performance thereof is deteriorated. On the other hand, the inventors of the present invention have already focused on the intrinsic birefringence and photoelastic coefficient and selected three or more kinds of monomer components (repeating unit structures) each having a different combination of signs, By adjusting the copolymerization composition ratio so as to obtain a polymer which does not cause orientation birefringence and photoelastic birefringence. When a polymer synthesized by such a method is used, an optical film, an optical element, or a component having almost zero birefringence can be obtained, which is an extremely important technique in applications requiring such a low birefringence.

Further, when this technique is applied, it becomes possible to synthesize a polymer which is easy to exhibit orientation birefringence by adjusting the intrinsic birefringence to an appropriate value. For example, in the case of a retardation film of a liquid crystal display, orientation birefringence and thickness are adjusted so as to obtain a desired retardation by stretching the film in a manufacturing process, and industrially, from a characteristic of a manufacturing apparatus, The range of the stretching condition such as the above is also limited in reality. That is, in order to obtain a desired orientation birefringence at an easy-to-produce stretching magnification, it is desirable that the intrinsic birefringence be within a certain range.

Various types of retardation films are industrially manufactured and marketed and appropriately selected and used in accordance with the mode and configuration of the liquid crystal display. Hereinafter, a preferable range of the intrinsic birefringence in terms of design will be described taking as an example a quarter wavelength plate used in many liquid crystal displays. In principle, a quarter wavelength retardation is imparted to a quarter wavelength plate, in which the polymer has a birefringence wavelength dependency, a visible light ray does not have a single wavelength but a wavelength of about 400 nm to 800 nm It is generally designed on the basis of a wavelength in the vicinity of the wavelength of green light (for example, around 550 nm) having a high visibility (visual sensitivity). Again, when designing at a wavelength of 550 nm, first the quarter wavelength is 137.5 nm. A commercially available product of a retardation film is usually about 100 탆 or less in thickness. Recently, research and development are proceeding aiming at further thinning of about 20 탆. Here, the orientation birefringence by the above formula (2) _or Δn is about 1.4 × 10 ^-3, in the high degree of orientation f = 0.1 obtained by the conventional stretching, the above-described formula (3) for a film having a thickness of 100μm The intrinsic birefringence Δn ⁰ calculated by the above equation is about 0.014. With the recent enhancement of the stretching technique, it is also possible to obtain a higher degree of orientation, and hence the absolute value of the intrinsic birefringence required for the film material is low. Taking them into consideration, the absolute value of the intrinsic birefringence in producing the retardation film is preferably 0.01 or more, more preferably 0.05 or more, and more preferably 0.1 or more. The orientation degree f can be measured by an infrared absorption dichromatic method described later. Further, when it is difficult to measure the degree of orientation, crystalline If the In, the absolute value of the orientation birefringence Δn of the film _or in a thickness of about 100μm or less 1.4 × 10 ^-3 or more to lower the polymer, the absolute value of the intrinsic birefringence estimated to be less than 0.01 can do. The reason for such estimation is that most of the polymers that do not satisfy this condition are not reported except for the crystalline polymer. As described above, in some applications, such as optical films for liquid crystal displays, it is particularly important to adjust the intrinsic birefringence of the polymer to substantially zero or a desired value as appropriate. In view of this point, .

The inventors of the present invention found the following serious fact in the process of developing an optical film such as a retardation film designed by the above-described technique as a product suitable for the demand described above, and found that, in an environment in which a product using an optical film is used And the temperature of the optical film may rise due to the heat generated during operation of the mounted product. Thus, it has been recognized that there is a need to improve the technique proposed in the foregoing. In other words, the inventors of the present invention measured the temperature dependence of the intrinsic birefringence of the polymer in the course of the detailed examination, and found that the value of the intrinsic birefringence is not constant with respect to temperature but varies, and the tendency increases with increasing temperature In the past, I made a new discovery that was not recognized at all. Until now, intrinsic birefringence of a polymer has usually been measured at room temperature (room temperature), and various discussions have been made as to the inherent value depending on the polymer. This means that various developments have been performed on the premise of the quality of the product under the condition of room temperature (normal temperature). On the other hand, for example, the use environment of a liquid crystal display employing an optical film covers a wide variety of fields, and under a very cold condition, under a summer vehicle or a working environment accompanied by heat generation, Are often used under the conditions of. In addition, it is known that the electronic device itself generates heat during operation, and the optical film is also influenced by the temperature in this respect. In view of such a situation, the inventors of the present invention have proposed an optical film product capable of stably expressing superior performance in consideration of the temperature dependency of intrinsic birefringence of a polymer found by the present inventors in the development of an optical film In order to do so. According to the study by the inventors of the present invention, it has been found that, for example, the intrinsic birefringence of a stretching table (TAC) of a retarder used in a VA liquid crystal polarizing plate used in a liquid crystal TV has temperature dependency and a tendency of temperature dependency I could. This is because, in order to make the polarizing plate mounted on a product that generates heat at least at the time of operation to have a higher quality than that of the conventional one, it is necessary to reduce the temperature dependence of the intrinsic birefringence found by the present inventors to the required performance, It means that it becomes important to do development.

Here, the present inventors have studied the temperature dependency of the intrinsic birefringence of the polymer in more detail so far. First, it was confirmed that the temperature dependency of the intrinsic birefringence attributable to the orientation of the main chain of the polymer chain was also temperature-dependent even in the polymer species having almost zero intrinsic birefringence (that is, almost no orientation). Further, as a result of measuring the rate of change (intrinsic birefringence temperature coefficient) with respect to the temperature of the intrinsic birefringence for various polymers, they are also inherent properties of the polymer, and the fact that the sign is positive (+) and negative Confirmed.

As described above, the inventors of the present invention have found that by using the results of conventional measurements on the intrinsic birefringence and photoelastic coefficient, it is possible to select three or more kinds of monomer components (repeating unit structures) Is adjusted to be substantially zero, and a polymer which essentially does not cause orientation birefringence and photoelastic birefringence is obtained. However, the above-mentioned new discovery is that there is a temperature dependence in the measurement result of the intrinsic birefringence of each homopolymer which is conventionally used at the time of determining the above monomer composition, which is considered to exhibit an intrinsic value regardless of temperature, It has been recognized that it is necessary to develop a new technology in consideration of this point in order to provide an optical film in which excellent performance is stably maintained even under an environment of a wide range of use temperatures or in the case where a heat generation accompanies an operation of a mounted apparatus It came to the following. As a result of detailed examination under the above recognition, the present inventors have found a new finding that the rate of change with respect to the temperature of the intrinsic birefringence (intrinsic birefringence temperature coefficient) is a characteristic inherent to the polymer, and by using this, It is possible to realize the polymer design in which the influence due to the temperature change is suppressed in consideration of the dependency, and the present invention has been accomplished.

More specifically, in the present invention, attention is paid to the fact that the temperature dependence (intrinsic birefringence temperature coefficient) of the intrinsic birefringence of the homopolymer indicates positive or negative (positive), respectively, (Polymer) or the like having a desired intrinsic birefringence temperature by appropriately selecting a unit structure and adjusting it to an appropriate copolymerization ratio. A polymer which has an intrinsic birefringence of almost zero and an intrinsic birefringence temperature coefficient of zero (the birefringence does not change with temperature and is always zero), which is realized by the technique provided by the present invention, or a polymer having an intrinsic birefringence And the polymer having an intrinsic birefringence temperature coefficient of zero is considered to be particularly promising when it is used as a retardation film for a liquid crystal display as described below. The retardation film is used for compensating birefringence of a liquid crystal layer and other optical films of a liquid crystal panel (three-dimensionally canceling birefringence from each other and eliminating the influence of birefringence), and stably If you can compensate, it is extremely useful. Further, according to the technique provided by the present invention, for example, when the birefringence of a liquid crystal layer or another optical film is changed depending on the temperature, the opposite intrinsic birefringence temperature coefficient And it is also possible to obtain a remarkable practical effect that the compensation method can be made various.

In addition, as described above, it is possible to reliably and reliably obtain a material exhibiting the intrinsic birefringence of a desired value, to reduce the temperature dependency thereof, and to reliably and reliably prevent the resin material from suppressing the intrinsic birefringence from varying with temperature If an optical film can be obtained, the optical film such as a retardation film obtained by using this material is stably retained in intrinsic birefringence with respect to temperature change, and its performance is stably maintained. Therefore, a liquid crystal display constructed using such a retardation film or the like is an excellent product capable of stably maintaining a high performance even when it is used in various temperature environments, or when a mounted device causes heat generation accompanying operation .

The optical resin material in which the temperature dependency of the intrinsic birefringence of the present invention is reduced can be performed in the same manner as in the designing method in which the polymer proposed in the present invention has a substantially zero intrinsic birefringence and a photoelastic coefficient of zero. As a result, as will be described later, a resin material which is an object of the present invention and which is very useful for optical applications in which the intrinsic birefringence is very small and whose temperature dependence is reduced, or a material having intrinsic birefringence at a desired value, When a monomer composition is designed by the following formula and the synthesis conditions of the resin are determined so as to conform to the obtained monomer composition, a resin material useful for optical applications in which dependence is reduced can be easily and reliably obtained with a stable optical film.

Here, first, with respect to the designing method for obtaining a copolymer having the intrinsic birefringence of almost zero and the photoelastic coefficient of zero proposed by the inventors of the present invention, methyl methacrylate (MMA) and 2,2,2-trifluoro (TFEMA), and benzyl methacrylate (BzMA) will be specifically described as an example.

The intrinsic birefringence? _N ⁰ of the ternary copolymer obtained by synthesizing the above three monomer components so as to _have a mass ratio of W _PMMA , W _PTFEMA and W _PBzMA , respectively, is obtained by using each intrinsic birefringence of a homopolymer synthesized from each monomer , And can be obtained by the following equation (4). The photoelastic coefficient C of the ternary copolymer obtained by synthesizing the monomer component so as to be in the mass ratio of W _PMMA , W _PTFEMA , and W _PBzMA can be calculated by the following equation using the respective photoelastic coefficients of the homopolymer synthesized from the respective monomers 5). The following formula (6) is a formula showing the monomer composition of the ternary copolymer, and indicates that the three monomer components are copolymerized in a mass ratio (%) of W _PMMA , W _PTFEMA and W _PBzMA .

In the above formula (4), Δn ⁰ _PMMA represents intrinsic birefringence of a homopolymer (PMMA) of MMA, Δn ⁰ _PTFEMA represents intrinsic birefringence of a homopolymer (PTFEMA) of TFEMA, Δn ⁰ _PBzMA represents the intrinsic birefringence of _BzMA Represents the intrinsic birefringence of the homopolymer (PBzMA). In the formula (5), C _PMMA represents the photoelastic coefficient of the homopolymer of MMA, C _PTFEMA represents the photoelastic coefficient of the homopolymer of _TFEMA , and C _PBzMA represents the photoelastic coefficient of the homopolymer of _BzMA .

In the formula (4), the value of the intrinsic birefringence Δn ⁰ of the ternary copolymer at the left side is zero (Δn ⁰ = 0), and the value of the photoelastic coefficient C of the ternary copolymer at the left side in the formula (5) (Hereinafter also referred to as a zero-zero birefringent polymer) in which both of the intrinsic birefringence? N ⁰ and the photoelastic coefficient C are zero, by solving the equation by solving the equation ) of the monomer _{composition, W PMMA / W PTFEMA / W} PBzMA = 52.0 / 42.0 / 6.0 of MMA and TFEMA and BzMA is obtained, which enables the synthesis of. When the ternary copolymer having such a monomer composition is actually synthesized and its intrinsic birefringence and photoelastic coefficient are measured, it becomes almost zero under a temperature condition of 25 ° C.

The design method of the ternary copolymer based on the above simultaneous equations is easier to understand when considered from Fig. Fig. 8 is a graph in which the photoelastic coefficient is taken on the ordinate axis and the intrinsic birefringence is taken on the abscissa axis, which is called "birefringence map" by the present inventors. The values of PMMA, PTFEMA and PBzMA of the homopolymer composed of the respective monomers are plotted in Fig. 8, and it can be seen that the triangle connecting them is the origin. As is apparent mathematically, in this case, a solution is obtained by setting the left sides of the above-mentioned equations (4) and (5) to zero. Further, by measuring the intrinsic birefringence and the photoelastic coefficient of various homopolymers and plotting the values thereof in a birefringence map, it is possible to obtain a zero-zero birefringent polymer as a copolymer of any combination of monomers It is possible to visually judge whether or not it is possible. Then, for the combination in which the solution including the origin (zero) is obtained, the monomer composition is obtained by solving the equations (4) to (6), and a birefringent polymer can be prepared easily and reliably with zero intrinsic birefringence and photoelastic coefficient.

(Method for measuring birefringence)

The " intrinsic birefringence of the polymer " in the present specification is measured by the following method. First, a polymer solution to be measured is adjusted using a suitable organic solvent, a film is prepared from the solution, and the orientation birefringence and the degree of orientation thereof are measured using the obtained film as follows. The intrinsic birefringence of the polymer was determined. Taking the three-component polymer composed of the monomer as an example, first, the obtained polymer was put into a sample tube made of glass together with tetrahydrofuran in a mass ratio of four times, and stirred to sufficiently dissolve the polymer. The polymer solution was developed in the form of a glass plate to a thickness of about 0.3 mm using a knife coater, allowed to stand at room temperature for one day, and dried. Next, the obtained film was taken out from the glass plate, further dried in a reduced pressure dryer at 60 ° C for 48 hours, and the obtained polymer film having a thickness of about 40 μm was processed into a dumbbell shape and then subjected to a tensilon general purpose tester (Manufactured by ORIENTEC Co., Ltd.). At this time, films having several degrees of orientation f were prepared by adjusting the stretching temperature in the range of 120 to 140 占 폚, the stretching speed in the range of 2 to 30 mm / min, and the stretching ratio in the range of 1.1 to 3.0. The orientation birefringence of the stretched film was measured using an automatic birefringence measuring device ABR-10A (manufactured by Uniopt Co., Ltd.). The degree of orientation of the stretched film was measured by the infrared absorption dichroism method. Then, the intrinsic birefringence of the polymer was determined by dividing (or extrapolating) the value of the orientation birefringence measured as described above by the degree of orientation of the stretched film. The intrinsic birefringence of the polymer film measured by the above-mentioned method was 0.16 x 10 < ^-3 > at 25 DEG C and was a size that can be regarded as almost zero at room temperature.

(Temperature dependence of intrinsic birefringence)

Using a polymer having intrinsic birefringence of almost zero, which was made of the ternary copolymer (MMA / TFEMA / BzMA = 52.0 / 42.0 / 6.0) obtained as described above, it was hot-rolled 40 mm at 102 ° C and 40 mm / min, Then, the temperature dependency of the intrinsic birefringence was examined with respect to the sample stored at room temperature for 24 hours while controlling the temperature at 16 ° C to 70 ° C. Specifically, the retardation (Re) when the temperature was raised by the temperature control device was measured. Fig. 2 shows measurement results of the orientation birefringence. This is obtained by dividing the measured retardation by the film thickness of 28 占 퐉. The intrinsic birefringence shown in Fig. 3 is obtained by dividing this by the orientation degree f = 0.107 of the polymer molecular chain in the polymer film. As can be seen from these figures, birefringence was zero at around room temperature of 25 ° C, but birefringence increased with increasing temperature. As can be seen from these figures, this temperature dependence was in a linear relationship with the relative temperature. Further, when the value of the orientation birefringence 0.10 占^10-3 is multiplied by a thickness of 80 占 퐉 of a general polarizing plate protective film, it can be seen that it corresponds to 8 nm by retardation. Generally, it can be seen that the retardation of 1 nm can be visually recognized when placed between quadrangularly polarized (orthogonal polarizing plates), so that it is understood that the influence of the birefringence change due to the temperature change is large.

(Examination of Temperature Dependence of Intrinsic Birefringence of Polymer)

From the above results, the present inventors conducted the same test on optical films having various monomer compositions and examined the temperature dependency of intrinsic birefringence, and an example of the result is shown in Fig.

The example shown in Fig. 4 is a two-component copolymer comprising MMA / MeMI (methylmaleimide) and has a copolymerization composition of MMA / MeMI = 80/20. As shown in Fig. 4, it was confirmed that the intrinsic birefringence of the polymer exhibited temperature dependency, as in the case of the three-component system copolymer shown in Fig. 3 which was shown earlier. The intrinsic birefringence temperature coefficient d? N ⁰ / dT was 2.9 × 10 ^-5 ° C ^-1 . Also, although not shown, it was confirmed that both the polymer showing positive positive birefringence at room temperature and the polymer having negative (-) intrinsic birefringence at room temperature all had temperature dependency.

(Temperature dependence of intrinsic birefringence of each homopolymer)

The polymers showing the results in FIG. 3 and FIG. 4 all showed a positive correlation with respect to temperature, but the degree thereof was not uniform but varied depending on the monomer composition. Here, in order to examine the difference in degree, the degree of correlation was compared with the amount of change of? N per 1 占 폚 with respect to homopolymers corresponding to various monomers. Table 1 shows the intrinsic birefringence temperature coefficient d? N ⁰ / dT (n), which is the change amount of? N per 1 ° C, obtained by measuring the intrinsic birefringence Δn ⁰ of each polymer at 25 ° C. Respectively. As a result, the degree of correlation with temperature tended to depend on the side chain structure of each polymer. For example, it was suggested that polymers having a stiff (rigid) structure are low, and polymers having a structure having a high rigidity and a high polarization anisotropy are high. In Table 1, PPhMA is the abbreviation of the homopolymer of phenyl methacrylate, PMI is the abbreviation of the homopolymer corresponding to the polymaleimide, PMeMI is the abbreviation of the homopolymer corresponding to the polymethylmaleimide, , The abbreviation of homopolymer corresponding to polyethylmaleimide, PCHMI is the abbreviation of homopolymer corresponding to polycyclohexylmaleimide, and the other is abbreviation of homopolymer as described above.

[Table 1]

Temperature dependence of intrinsic birefringence of each homopolymer

The monomer forming the copolymer or polymer constituting the optical resin material of the present invention is not limited to the above-mentioned monomers, and examples thereof include aromatic monomers, acrylic monomers, vinyl monomers, maleimide monomers , Polar monomers and the like can be suitably used.

Examples of the aromatic monomer include styrene, alpha-methylstyrene, benzyl (meth) acrylate, alkylphenoxypolyalkylene glycol (meth) acrylate, 6- (4,6-dibromo-2-isopropyl (4,6-dibromo-2-s-butylphenoxy) -1-hexyl acrylate, 2,6-dibromo-4-nonylphenyl acrylate Dicyclopentyl acrylate, 2- (1-naphthyloxy) -1-ethyl acrylate, 2- (2-naphthyloxy) Octyl acrylate, 8- (1-naphthyloxy) -1-hexyl acrylate, 6- (2-naphthyloxy) 2-naphthyloxy) -1-octyl acrylate, 2-phenylthio-1-ethyl acrylate, and phenoxyethyl (meth) acrylate.

Examples of the acrylic monomer include alkyl (meth) acrylate and alkyl (cyclic) or (meth) acrylates having a heterocyclic ring on the side chain. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, (Meth) acrylate, n-octyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl N-decyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, Acrylate, and the like. These may be used singly or in combination of two or more kinds. Also, alkyl (meth) acrylate means alkyl acrylate and / or alkyl methacrylate.

Examples of the vinyl-based monomer include vinyl acetate, vinyl chloride, vinyl toluene, and various vinyl ethers.

Examples of the maleimide-based monomer include N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (2-ethyl) phenylmaleimide, N- N- (4-methylphenyl) maleimide, N- (2-methylphenyl) maleimide, N- ) Maleimide, N- (2,6-diethylphenyl) maleimide, N- (2,6-diisopropylphenyl) maleimide, N- (2-chlorophenyl) maleimide, N- (2-bromophenyl) maleimide, N- (2-chlorophenyl) maleimide, N- , N- (2,4-dimethylphenyl) maleimide, para-tolyl maleimide, and the like. Examples of the N-alkyl-substituted maleimide include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, Ni-propylmaleimide, N-butylmaleimide, N-butyl maleimide, Nt-butyl maleimide, Nn-pentyl maleimide, Nn-hexyl maleimide, Nn-heptyl maleimide, Nn-octyl maleimide, N-lauryl maleimide, N Alkyl-substituted maleimides such as stearyl maleimide, N-cyclopropyl maleimide, N-cyclobutyl maleimide, N-cyclohexyl maleimide and N-methyl citraconimide.

Examples of the polar monomer include ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated phosphoric acids, hydroxyl group-containing monomers and nitrogen-containing monomers.

Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, carboxylethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, have.

Examples of other polar monomers include hydroxyl group-containing monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate; , Amide group-containing monomers such as N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide and N-butoxymethyl Amino group-containing monomers such as 2- (N, N-dimethylamino) ethyl (meth) acrylate; Glycidyl group-containing monomers such as glycidyl (meth) acrylate; Alkoxysilyl group-containing monomers such as propyltrimethoxysilane (meth) acrylate, propyldimethoxysilane (meth) acrylate, propyltriethoxysilane (meth) acrylate and the like; (meth) acrylonitrile, N- ) Acryloylmorpholine, N-vinyl-2-pyrrolidone, and the like.

Examples of other monomers include acrylonitrile, methacrylonitrile, and the like. Further, it is also possible to use acrylic acid esters such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (Meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

The above (co) polymer can be produced by ordinary solution polymerization, bulk polymerization, emulsion polymerization or suspension polymerization, active radiation polymerization and the like.

The optical resin material of the present invention is composed of a copolymer or polymer formed from the monomer as described above and a low molecular weight organic compound capable of orienting in the polymer, and is made of a resin material having reduced temperature dependence of intrinsic birefringence It is possible. Examples of the low-molecular organic compound having anisotropy of the polarizability that can be used at that time and which can be oriented in the polymer include various plasticizers exemplified below. Representative plasticizers include, for example, polyoxyethylene aryl ethers, dialkyl adipates, 2-ethylhexyldiphenyl phosphate, t-butylphenyldiphenyl phosphate, di (2-ethylhexyl) adipate, toluenesulfonamide, di Propylene glycol dibenzoate, polyethylene glycol dibenzoate, polyoxypropylene aryl ether, dibutoxyethoxyethyl formate, and dibutoxyethoxyethyl adipate. In the present invention, in particular, a compound containing two aromatic groups is effective. For example, 1,2-diphenylethene (alias: trans-stilbene) or diphenylsulfide, diethyleneglycol di Benzoate, dipropylene glycol dibenzoate, benzyl benzoate, and 1,4-cyclohexanedimethanol dibenzoate. In the method for counting the number of "aromatic groups", condensed rings such as naphthalene rings are counted as one.

The intrinsic birefringence (Δn ⁰ ) and the intrinsic birefringence temperature coefficient (Δn ⁰ / Δn ⁰ ) of the (co) polymer were determined by adding a low molecular weight organic compound as described above to the dT) can be changed. The results of this review are shown below. Concretely, the optical resin material obtained by adding these low-molecular organic compounds to PMMA as the low-molecular organic compound, respectively, is taken as an example, and the intrinsic birefringence (? N ⁰ ) and intrinsic birefringence temperature coefficient (n ⁰ / dT), respectively. The results are summarized in Table 2 below. At this time, the amount of the low-molecular organic compound added to the PMMA was changed to two kinds of 3 mass% and 10 mass%, respectively, and a film was produced. For comparison, intrinsic birefringence (Δn ⁰ ) and intrinsic birefringence temperature coefficient (Δn ⁰ / dT) originally of PMMA without addition of a low-molecular organic compound are also shown in Table 2. As shown in Table 2, by adding a low molecular weight organic compound to PMMA as the (co) polymer, the intrinsic birefringence (n ⁰ ) of the (co) polymer and the intrinsic birefringence temperature coefficient (n ⁰ / dT ) Was changed. This means that the intrinsic birefringence temperature dependency of the obtained film can be reduced by a simple method of adding a low molecular weight organic compound as exemplified above to the (co) polymer in an appropriate amount.

[Table 2]

The intrinsic birefringence and the intrinsic birefringence temperature coefficient when a low molecular weight organic compound is added to PMMA

The optical resin material in which the temperature dependency of the intrinsic birefringence specified in the present invention is reduced can be easily and surely obtained by the following method. For example, the intrinsic birefringence inherent in the copolymer obtained by copolymerizing the above-mentioned monomer components and the intrinsic birefringence temperature coefficient are both 0 (zero), or the intrinsic birefringence is the intrinsic birefringence Is assumed to be a desired value having an absolute value of 0.01 or more and that the intrinsic birefringence temperature coefficient becomes 0 (zero), the mass fraction of each monomer can be calculated by solving the following simultaneous equations, The composition ratio of the monomer constituting the copolymer can be determined. Therefore, the copolymer exhibiting the intended performance can be easily obtained by blending monomers in consideration of the reactivity of each monomer, the reaction conditions, and the like so as to obtain the target monomer composition ratio obtained above.

[In the formula (i), Δn ⁰ ₁ is, first indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _2, the second indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _N is the N-th homopolymer Lt; / RTI > In the above formula _{^{(ii), dΔn 0 1 /}} dT , the first represents the number of intrinsic birefringence thermometer of the second homopolymer, dΔn ⁰ ₂ / dT, the second of the second homopolymer intrinsic birefringence represents the temperature coefficient, dΔn ⁰ _N / dT represents the intrinsic birefringence temperature coefficient of the Nth homopolymer. In the formula (iii), W ₁ , W ₂ and W _N represent the mass fraction (%) of the first, second and Nth monomers, respectively.

More specifically, for example, a resin material useful for an optical film in which the intrinsic birefringence aimed at by the present invention is a polymer of almost zero or a desired value, and whose temperature dependence of the intrinsic birefringence is reduced, In the case of a copolymer comprising a monomer of the following formula First, the kind of the monomer component capable of forming a polymer having substantially zero intrinsic birefringence is selected by the method shown in Fig. 8 described above. Here, it is assumed that three kinds of monomers from the first to the third are selected. Next, the temperature dependence of the intrinsic birefringence was examined for each film made of the corresponding homopolymer of each of these three kinds of monomers as described above, and the intrinsic birefringence temperature coefficient d? N ⁰ / dT I ask. The simultaneous equations (iv) to (vi) are established by assuming that the mass fractions (%) of the three kinds of monomers from the first to the third are W ₁ , W ₂ and W ₃ , respectively. And, for example, on the (iv) zero (dΔn ⁰ / dT = ⁰⁾ the left-hand zero formula ^{(Δn 0 = 0), (} v) the left-hand side of the equation, solution of W _1, W _2, W ₃ A polymer having an intrinsic birefringence of almost zero and an intrinsic birefringence temperature coefficient of zero, and having no temperature dependence on the orientation birefringence can be obtained. At this time, if the value of the left side of the formula (iv) and the value of the left side of the formula (v) are desired values, the orientation birefringence can be adjusted to a desired value, An optical film useful for a phase difference film of, for example,

The above formulas (i) to (iii) are expressed by the following three formulas (N = 3).

The design method of the ternary copolymer for obtaining a polymer with an intrinsic birefringence thermometer of a polymer is, for example, a polymer having intrinsic birefringence nearly zero by the simultaneous equations (iv) to (vi) Like FIG. 8, it is easier to understand when considered from FIG. 1 is used for designing a monomer composition ratio for synthesizing an optical resin material in the embodiment described later. It is assumed that the first monomer in the above formula is MMA, the homopolymer corresponding to the first monomer is PMMA, The second monomer is PhMA, the corresponding homopolymer is PPhMA, the third monomer in the above formula is EMI or BzMA, and the corresponding homopolymer is PEMI or PBzMA. In FIG. 1, the intrinsic birefringence Δn ⁰ at 25 ° C. (room temperature) is taken on the horizontal axis, the intrinsic birefringence temperature coefficient dΔn ⁰ / dT is taken on the vertical axis, and PMMA, PPhMA, PBzMA and PEMI The intrinsic birefringence? N ⁰ and the intrinsic birefringence temperature coefficient d? N ⁰ / dT are plotted, respectively.

From Figure 1, is a triangle connecting the respective plots of PMMA and PPhMA with a triangle and, PMMA and PPhMA and PBzMA connecting each plot of PEMI, be seen that including the origin ^{(Δn 0 = dΔn 0 / dT} = 0) have. As is apparent mathematically, in these cases, if the left sides of the above equations (iv) and (v) are all set to zero, a solution is obtained. In this manner, the intrinsic birefringence index n ⁰ / dT obtained by examining the intrinsic birefringence Δn ⁰ and temperature dependency at 25 ° C. (room temperature) is measured for various homopolymers, and these values are plotted in the map When a copolymer of any combination of monomers is used, it becomes possible to visually judge, for example, whether or not the intrinsic birefringence is almost zero and can be a polymer with a high birefringence thermometer. Then, the monomer composition is obtained by solving the equations (iv) to (vi) for the combination in which the solution including the origin is obtained. When the optical composition is obtained easily and reliably, the orientation birefringence is almost zero, The composition ratio of the polymer is obtained. Therefore, by using the optical resin material of the present invention prepared by copolymerizing a plurality of monomers under the above-described design, it is possible to provide a resin composition for optical use which exhibits stable optical characteristics even when used under various temperatures, It becomes possible to provide a more useful optical film product. Further, not limited to the description herein, by solving the equation for any of the N component in the equation (i) to (iii) under ^{Δn 0 = dΔn 0 / dT =} 0, and the intrinsic birefringence is substantially zero, Further, a polymer in which the intrinsic birefringence temperature coefficient is almost zero and the temperature dependency of intrinsic birefringence is reduced can be designed. Normally, when the number of components is four or more, a plurality of monomer compositions of the copolymer that can solve the equation are obtained.

[Example]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. The term "part" or "%" in the text is on a mass basis unless otherwise specified.

(Design of monomer composition ratio)

In this embodiment, PhMA (first monomer), BzMA (second monomer), and EMI (third monomer), which are the three kinds of monomers shown in FIG. 1, are selected, , The optical film produced by the obtained copolymer was designed so that the intrinsic birefringence and the intrinsic birefringence temperature coefficient become zero together. Specifically, the composition ratios of the above-mentioned three kinds of monomers were obtained by calculation as described above using the following formulas (iv) to (vi).

Specifically, in this embodiment, in order to design a copolymer capable of obtaining an optical film in which the intrinsic birefringence and the intrinsic birefringence temperature coefficient coincide with each other, the following simultaneous equations (iv) to (vi) The combination of monomers was then calculated. (Vii), (viii) and (ix) by substituting the intrinsic birefringence and the intrinsic birefringence temperature coefficient for each of the homopolymers used in the above into the equations (iv) to (vi).

When the simultaneous equations are calculated by setting the left sides of the equations (vii) and (viii) to 0 (zero), the monomer composition ratio of MMA / PhMA / BzMA = 33/34/33 In the case of the synthesized copolymer, the intrinsic birefringence and the intrinsic birefringence temperature coefficient of the optical film made of the copolymer are expected to be zero together.

(Synthesis of Polymer)

Hereinafter, the procedure of synthesizing the polymer so that the mass fraction of the three kinds of monomers calculated in the above examples is a monomer composition of MMA / PhMA / BzMA = 33/34/33 will be described. (MMA) and phenyl methacrylate (PhMA) were added to a sample tube made of glass in consideration of the reactivity and the like of each monomer used in the polymerization, aiming at a copolymer satisfying the composition ratio obtained by calculation. ) And benzyl methacrylate (BzMA) were blended so as to have a mass ratio of 41/22/37. Perbutyl O (trade name, manufactured by NOF CORPORATION) as a polymerization initiator was added in an amount so as to be 0.2 mass% with respect to the total amount of these monomers. These raw materials were mixed and stirred, sufficiently homogenized, filtered through a membrane filter, and transferred to a test tube. These test tubes were placed in a hot bath at 70 ° C and polymerized for 24 hours. Subsequently, heat treatment was carried out in a drier at 90 캜 for 24 hours.

The polymer thus obtained was dissolved in methylene chloride in an amount of 10 times, and the resulting polymer solution was added dropwise to methanol to precipitate the polymer. The polymer was filtered and sufficiently dried to remove the remaining monomers to obtain a ternary copolymer. The copolymer was measured for its copolymerization ratio using ¹³ CNMR, and a desired agreement with a desired mass fraction was obtained.

The intrinsic birefringence at 25 ° C calculated from the above formulas (iv) and (v) in the monomer ratio of the measured copolymer is Δn ⁰ = 0.11 × 10 ^-3 and the intrinsic birefringence temperature coefficient is dΔn ⁰ / dT = 0.32 x 10 ^-5 캜 ^-1 .

(Measurement of Optical Properties of Film Prepared from Polymer)

A film was prepared from the polymer obtained as described below, and the optical properties of the obtained film were examined. First, the obtained polymer was placed in a sample tube made of glass together with methylene chloride five times in a mass ratio and stirred to dissolve it sufficiently. Next, the obtained polymer solution was developed in the form of a glass plate to a thickness of about 0.3 mm using a knife coater, allowed to stand at room temperature for one day, and dried. Then, the obtained film was removed from the glass plate and further dried in a reduced-pressure dryer at 90 캜 for 24 hours. The thus obtained polymer film having a thickness of about 40 占 퐉 was processed into a dumbbell shape, and uniaxial stretching was carried out by a Tensilon general-purpose tester (manufactured by Orientech Co., Ltd.). At this time, the stretching temperature was 114 占 폚, the stretching speed was 50 mm / min. , A stretching magnification of 1.5 to 2.5, and the like, to produce films having several degrees of orientation f. Then, the birefringence of the stretched film was measured using an automatic birefringence measuring device ABR-10A (manufactured by Uni-Opt Co., Ltd.). The degree of orientation of the stretched film was measured by the infrared absorption dichroism method. As a result, the intrinsic birefringence of the film prepared above was -0.16 x 10 < ^-3 > at 25 DEG C and was a size that can be regarded as almost zero.

(Temperature dependence of intrinsic birefringence of the film)

The temperature-dependency of the orientation birefringence and the intrinsic birefringence of the sample thus obtained after the stretching was controlled at 12 占 폚 to 70 占 폚 with respect to a sample stored at room temperature for 24 hours. Specifically, the retardation (Re) when the temperature was raised by the temperature control device was measured. The orientation birefringence was obtained by dividing this by the film thickness, and plotted with respect to the orientation degree f of the polymer, and the result is shown in Fig. 5 (A). Fig. 5 (B) shows the intrinsic birefringence obtained from the orientation birefringence and the degree of orientation f and the change in temperature. Here, the orientation degree f was regarded as being constant in the measurement temperature range. As can be seen from these figures, the birefringence of the film made of the copolymer prepared in this Example hardly changes even when the temperature is increased, and the temperature dependency is reduced. The intrinsic birefringence temperature coefficient of the prepared film was d? N ⁰ / dT = 0.15 × 10 ^-5 ° C ^-1 . Further, the calculation of the intrinsic birefringence temperature coefficient was obtained from the data at 15 캜 to 70 캜. In any case of the present specification, the intrinsic birefringence temperature coefficient was calculated from the data at 15 캜 to 70 캜. For comparison, also in FIG. 5, the measurement results of PMMA were plotted in the same manner.

The film obtained from the copolymer was prepared in the same manner as in Example 1 except that a copolymer having the mass ratio of the monomer of the copolymer was set to MMA / PhMA / BzMA = 40/27/33 was prepared, and the intrinsic birefringence And the intrinsic birefringence temperature coefficient were obtained. As a result, the intrinsic birefringence at 25 ° C was Δn ⁰ = -0.22 × 10 ^-3 , and the intrinsic birefringence temperature coefficient was dΔn ⁰ / dT = 0.38 × 10 ^-5 ° ^-1 . The birefringence hardly changes even when the temperature is increased, and the temperature dependency is reduced.

Copolymer was prepared in the same manner as in Example 1 except that a copolymer of a three component system in which the mass ratio of the monomer of the copolymer was MMA / PhMA / EMI = 29/54/17 was prepared. The monomer composition was designed, . Then, the intrinsic birefringence and the intrinsic birefringence temperature coefficient at 25 ° C were determined for the film obtained from the copolymer. Fig. 6 shows the results. As a result, it was found that the intrinsic birefringence at 25 ° C was Δn ⁰ = -0.47 × 10 ^-3 and the intrinsic birefringence temperature coefficient was dΔn ⁰ / dT = -0.12 × 10 ^-5 ° C ^-1 . The copolymer prepared in this Example Even when the temperature of the film was raised, the birefringence hardly changed, and the temperature dependency was reduced.

(Measurement of Temperature Dependence of Intrinsic Birefringence of Polymer)

In the present invention, when examining the temperature dependency of the intrinsic birefringence, the film sample at the time of measuring birefringence is surely set to a desired temperature by using the structure shown in Fig. Reference numeral 1 in Fig. 7 denotes a sample holder whose center is a cavity, and a film sample is arranged in this cavity portion, so that the sample can be reliably held at a desired temperature. This sample holder has two thermocouples (thermocouples) indicated by 2 and 3 in Fig. 7, and the temperature of the sample is measured by these thermocouples. The circulation type handy cooler TRL, 108H, and LM (manufactured by THOMAS KAGAKU Co., Ltd.) for the closed system shown in FIG. 7 is operated appropriately, and the temperature of these thermocouples Is set to a desired temperature, the sample is brought to a desired temperature, and the birefringence is measured in this state. Reference numeral 5 denotes a recorder for recording information from a thermocouple. In the present invention, a touch-type paperless recorder TR · V550 (trade name, manufactured by KEYENCE CORPORATION) was used. Using this apparatus, measurement of intrinsic birefringence was performed using a film sample with strict temperature control.

1: Sample holder
2, 3: Thermocouple
4: Circulating handy cooler for sealed system
5: Recorder

Claims (10)

1. An optical resin material comprising a composite component system in which the number of components z defined by the condition that the number of elements x (x? 1) of the (co) polymer is included in the number of components and is 2 or more,
The composite-
A copolymer having a raw number x of 2 or more or a copolymer having a raw number x of 1 or a raw number x of 2 or more and at least one low molecular weight organic compound having anisotropy of polarizability and capable of orienting in the polymer And,
The combination of components constituting the complex component system may be,
At least one of the intrinsic birefringence temperature coefficient of each homopolymer corresponding to each monomer component forming the copolymer or the polymer and the intrinsic birefringence temperature coefficient commonly exhibited by the respective low molecular weight organic compound are different from each other Lt; RTI ID = 0.0 > a < / RTI >
The component ratio of each component constituting the complex component system is,
Wherein the optical birefringence temperature dependency is selected to cancel out by using a different sign relation with respect to the intrinsic birefringence temperature coefficient. The method according to claim 1,
The intrinsic birefringence? N ⁰ at each temperature is measured by using a uniaxially stretched film made of the aforementioned composite component in a state where the temperature of the film is controlled in the range of 15 to 70 ° C, The absolute value of the intrinsic birefringence temperature coefficient d? N ⁰ / dT at 15 ° C to 70 ° C, which is obtained as the change amount of the intrinsic birefringence per ° C, is in the range of 1.0 × 10 ^-5 (° C ^-1 ) or less and the temperature dependence of the intrinsic birefringence is reduced The optical resin material. An optical resin material comprising a composite component system in which the number of components, z, defined by the condition that the number x of raw materials of the copolymer (x? 2)
The composite-
Or a copolymer having a number of atoms x of 3 or more,
A copolymer having a number of atoms x of 2 or more and at least one low molecular weight organic compound capable of orienting in the polymer with anisotropy of polarization ratio,
The combination of components constituting the complex component system may be,
At least one of the sign of the intrinsic birefringence of each homopolymer corresponding to each monomer component forming the copolymer and at least one of the sign of the oriented birefringence common to the respective homopolymers of the low molecular weight organic compound is And also,
Wherein at least one of the intrinsic birefringence temperature coefficient of each of the homopolymers and the intrinsic birefringence temperature coefficient common to the respective homopolymers of the low molecular weight organic compound is selected to have a different sign from that of the other,
The component ratio of each component constituting the complex component system is,
Wherein the optical resin material is selected such that the intrinsic birefringence and the intrinsic birefringence temperature dependence represented by the optical resin are simultaneously canceled by using different sign relations with respect to the orientation birefringence and different sign relations with respect to the intrinsic birefringence temperature coefficient. The method of claim 3,
The intrinsic birefringence? N ⁰ at each temperature is measured by using a uniaxially stretched film made of the aforementioned composite component in a state where the temperature of the film is controlled in the range of 15 to 70 ° C, The absolute value of the intrinsic birefringence temperature coefficient d? N ⁰ / dT at 15 ° C to 70 ° C, which is obtained as the change amount of the intrinsic birefringence per ° C, is in the range of 1.0 × 10 ^-5 (° C ^-1 ) or less and the temperature dependence of the intrinsic birefringence is reduced The optical resin material. The method of claim 3,
An optical resin material comprising a copolymer formed by copolymerizing three or more kinds of monomer components,
The combination of the above three or more monomer components and the combination of these monomer components are such that the intrinsic birefringence Δn ⁰ at 25 ° C. of the uniaxially stretched film composed of each homopolymer corresponding to each monomer component and the temperature of the film are 15 in to a phase control in the range of 70 ℃ state, using the natural birefringence temperature dΔn ⁰ / dT obtained as a intrinsic birefringence variation in the measured Δn ⁰ respectively, 1 ℃ party intrinsic birefringence of the measurement results obtained at each temperature Lt; / RTI >
The intrinsic birefringence Δn ⁰ at 25 ° C. measured using a uniaxially stretched film made of the copolymer is adjusted to be almost zero at an absolute value of 3.0 × 10 ^-3 or less, is adjusted to a desired value less than the absolute value of 0.01, and, in either case, the absolute value of the intrinsic birefringence Temperature ⁰ dΔn / dT in the 15 ℃ to 70 ℃ so that 1.0 × 10 ^-5 (℃ ^-1) or less And the temperature dependency of the intrinsic birefringence is reduced. A method for producing an optical resin material according to any one of claims 1 to 5,
A raw material adjusting step of determining the kind of the monomer component of the complex component system selected as the raw material and determining the composition ratio of the selected two or more monomer components,
In the raw material adjusting step,
The intrinsic birefringence at each temperature was measured for each uniaxially stretched film corresponding to each monomer component while the temperature of the film was controlled stepwise in the range of 15 to 70 DEG C, From the measurement results, the intrinsic birefringence temperature coefficient d? N ⁰ / dT, which is the change amount of the intrinsic birefringence per 1 ° C,
A graph of a relationship between the intrinsic birefringence temperature coefficient d? N ⁰ / dT and the intrinsic birefringence? N ⁰ measured at 25 ° C is prepared,
From the relational graph, it can be seen that there is a combination in which the intrinsic birefringence Δn ⁰ measured at 25 ° C. and the intrinsic birefringence thermometer dΔn ⁰ / dT are zero, or the combination of the intrinsic birefringence temperature coefficient dΔn ⁰ / dT is zero , And a combination in which the absolute value of the intrinsic birefringence at 25 캜 is 0.01 or more may be present to determine the type of the monomer component,
The intrinsic birefringence Δn ⁰ measured at 25 ° C. inherent to the copolymer obtained by copolymerizing the selected monomer component is a desired value having an absolute value of intrinsic birefringence measured at zero or at 25 ° C. of 0.01 or more, It is assumed that the temperature coefficient d? N ⁰ / dT is zero and the mass ratio of each monomer component is calculated to determine the composition ratio of the monomer components to be combined,
Wherein the copolymer is synthesized by copolymerizing monomers obtained by using the monomer component selected and determined to have the monomer composition in the determined composition ratio. The method according to claim 6,
In determining the composition ratio of the monomer components to be combined, the monomer component is N (where N is an integer of 3 or more), and the intrinsic birefringence inherent in the copolymer obtained by copolymerizing these monomer components and the intrinsic birefringence temperature coefficient are both 0 Zero) or the desired value, and calculating the mass fraction of each monomer using the following simultaneous equations to determine the composition ratio of the monomers constituting the copolymer.

[In the formula (i), Δn ⁰ ₁ is, first indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _2, the second indicates the intrinsic birefringence of the second homopolymer, Δn ⁰ _N is the N-th homopolymer Lt; / RTI > In the above formula _{^{(ii), dΔn 0 1 /}} dT , the first represents the number of intrinsic birefringence thermometer of the second homopolymer, dΔn ⁰ ₂ / dT, the second of the second homopolymer intrinsic birefringence represents the temperature coefficient, dΔn ⁰ _N / dT represents the intrinsic birefringence temperature coefficient of the Nth homopolymer. In the formula (iii), W ₁ , W ₂ and W _N represent the mass fraction (%) of the first, second and Nth monomers, respectively. A method of producing an optical resin material according to any one of claims 1 to 5 or a method of producing an optical resin material according to claim 6 or 7, Wherein the film-like optical resin member is adjusted so as not to cause a dependency on the film. 9. The method of claim 8,
Further, a film-shaped optical resin member formed by forming a pressure-sensitive adhesive layer on at least one surface of the film. Wherein a film-shaped optical resin member according to claim 8 or 9 is used as a material for forming the polarizer.

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