JP2001208901A - Low birefringent optical resin material, its manufacturing method and its application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical resin material which is composed of a polymer resin and in which the birefringence is reduced without sacrificing its characteristics and its manufacturing method, and to provide various useful materials or articles by applying the optical resin material. SOLUTION: The low birefringent optical resin material is made by alignment treatment of a transparent polymer resin material in a state in which molecular alignment suppressing particles with a size smaller than the wavelength of light are mixed in the transparent polymer resin material. The molecular alignment suppressing particles are particles composed of a substance with isotropic polarization or particles with isotropy in shape. The extent of alignment produced in the polymer chain of the polymer resin material is suppressed due to the existence of the molecular alignment suppressing particles, and as a result, the birefringence induced by the alignment treatment is reduced. The optical resin material is advantageously used in a liquid crystal element or in an optical disc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low birefringence optical resin material, and more particularly, to a material having reduced birefringence and substantially no birefringence, or a degree to which birefringence is exhibited. The present invention relates to an optical resin material having a low content, a production method thereof, and an application thereof.

[0002]

2. Description of the Related Art Generally, in an optical resin material, birefringence is generated according to an actual processing method as widely known including its cause. That is, in almost all cases of a polymer resin generally used as an optical resin material, since the monomer forming the polymer has optical anisotropy due to the refractive index, the optical difference in this monomer is high. Anisotropy is exhibited in an optical resin material made of a polymer arranged or oriented in a certain direction, resulting in birefringence.

[0003] Specifically, a polymer resin produced by a polymerization reaction does not exhibit birefringence. This is because the polymer chains are randomly entangled, and no orientation occurs in the polymer chains. That is, in this state, since the optical anisotropy of each monomer is mutually canceled, the polymer resin does not exhibit birefringence. However, when such a polymer resin undergoes a molding process such as injection molding or extrusion molding, the random polymer chains are oriented by external force or the like applied at that time, and as a result, the obtained polymer resin is It shows birefringence.

FIG. 1 is an explanatory diagram showing the state of oriented polymer chains of a polymer resin and the birefringence exhibited thereby. As shown in this figure, the polymer resin that has undergone the molding step is generally in a state in which a large number of bonding units 1 forming the polymer chain are volumetrically bonded along a specific orientation direction. Here, the bonding unit is one of the monomers.
It is a unit based on molecules, and is represented by a rectangular figure in the figure, and the orientation direction is the horizontal direction in the figure. And, as described above, in almost all of the polymer resins used as the optical resin materials, each bonding unit 1 has optical anisotropy with respect to the refractive index. That is, the refractive index _npr regarding the polarization component in the direction parallel to the orientation direction is different from the refractive index _nvt regarding the polarization component in the direction perpendicular to the orientation direction (vertical direction in the figure).

[0005] Such optical anisotropy can be represented by a refractive index ellipsoid as is well known. FIG.
In the above, the elliptical mark 2 described in each connection unit 1 conforms to the notation system. For example, in the case of polymethyl methacrylate (PMMA), a binding unit [—CH ₂ —C (C
The refractive index of H ₃ ) (COOCH ₃ )-] is relatively small in the orientation direction and relatively large in the direction perpendicular to the orientation direction, and n _pr <n _vt , and is therefore shown in FIG. As can be seen, the index ellipsoid 3 when viewed on a macro scale is vertically long. As described above, when the refractive index _npr for the polarization component in the direction parallel to the orientation direction is different from the refractive index _nvt for the polarization component in the direction perpendicular to the orientation direction, the difference Δn (= _npr− n _vt ) is called the birefringence value.

The birefringence value Δn of a typical polymer resin used as an optical resin material is −
0.100, -0.00 for polymethyl methacrylate
43, +0.210 for polyphenylene oxide, +0.106 for polycarbonate, 0.027 for polyvinyl chloride, +0.105 for polyethylene terephthalate, and +0.044 for polyethylene.
In the present specification, the birefringence caused by the orientation of the polymer chain is called orientation birefringence, and the sign of the birefringence value Δn is positive (Δ
n> 0) is expressed as "the sign of the birefringence is positive", and the sign of the birefringence Δn is expressed as a negative (Δn <0) as "the sign of the birefringence is negative". It shall be.

[0007] Such orientation birefringence becomes a serious problem when polarization characteristics are involved in the application or application of optical resin materials. As a typical example, there is an optical component in a write / erase type magneto-optical disk device. In this write / erase type magneto-optical disk device, a polarized beam is used for a read beam or a write beam. , An optical element located in its optical path,
For example, if the disk itself or the lens shows birefringence, the reading or writing accuracy is adversely affected.

A liquid crystal element is one in which the birefringence of an optical element used has an important effect. This liquid crystal element has a structure in which the transmission / non-transmission of light is controlled by rotating a polarization plane of polarized light by a liquid crystal layer between a polarizer and an analyzer, which are made of orthogonal Nicols or parallel Nicols. Therefore, in the liquid crystal element, the birefringence of each of the constituent elements becomes a serious problem, and therefore, the selection range of the optical resin material used as the material of the constituent elements of the liquid crystal element is narrow and extremely limited.

Hitherto, various attempts have been made to reduce the orientation birefringence of an optical resin material, one of which is disclosed in International Publication No. WO 96/06370. In this technique, when a polymer chain of the polymer resin in the matrix is oriented by an external force, a low-molecular substance that can be oriented in the same direction as the orientation direction of the binding chain is added to a matrix made of a transparent polymer resin. In addition, the birefringence of the low-molecular substance reduces the alignment birefringence of the polymer resin.

More specifically, according to this technique, the polymer resin forming the matrix has an orientation birefringence having a positive or negative sign. It has been shown that the birefringence of the opposite sign to the orientation birefringence in the polymer resin, utilizing the fact that the birefringence of both are offset, to obtain a low birefringence optical resin material I have. In other words, in this optical resin material, the polymer chains are oriented when an action such as stress is applied from the outside in a process such as molding, and at this time, the low-molecular substance added is also oriented in the polymer chains. And the major axis direction of the refractive index ellipse in the low molecular substance oriented in accordance with the orientation of the polymer chain is a direction orthogonal to the major axis direction of the refractive index ellipse in the polymer resin. By taking advantage of this fact, the birefringence of the polymer resin is offset and reduced, and low birefringence is realized as a whole.

Such a technique has many advantages. For example, by adjusting the amount of the latter added to the former in accordance with the types of the polymer resin and the low-molecular substance to be combined, a resin whose overall birefringence is close to zero can be obtained. Moreover, this technology can be applied to any polymer resin in principle, and low-molecular substances do not substantially participate in the polymerization reaction of the polymer resin for the matrix. Because it has no reactivity to the monomer that gives the resin,
There are relatively few restrictions on the combination of the polymer resin and the low-molecular substance, so that a relatively large degree of freedom can be obtained in selecting the polymer resin for the optical resin material. Furthermore, low-molecular substances are compared with each unit molecule forming a high-molecular resin.
With respect to the refractive index, it generally has a larger optical anisotropy, and therefore, a desired effect can be obtained with a relatively small amount of addition. It can be used for optical resin materials.

However, in the technique of reducing the birefringence of the optical resin material by adding a low molecular substance, for example, the selection of the low molecular substance to be added is made in consideration of the high molecular resin for the matrix. The range is naturally limited. And a particularly important problem is to obtain a low-molecular substance exhibiting negative orientation birefringence,
It is actually difficult. That is, among the polymer resins widely used as optical resin materials, regardless of the case of polymethyl methacrylate or polystyrene having a negative birefringence, in the case of a polymer resin having a positive birefringence,
The range of low molecular weight materials having a negative birefringence to be applied to this may be so narrow that this method may not be applicable in practice. Specific examples of the polymer resin having a positive birefringence include, for example, polyethylene (Δn: +0.04
4), norbornene-based resin (Δn: for example +0.019)
2) can be mentioned.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is an optical resin material made of a polymer resin, wherein characteristics of the polymer resin are sacrificed. It is another object of the present invention to provide a low birefringence optical resin material in which the birefringence of the polymer resin is surely reduced irrespective of the sign, and a method for producing the same. Another object of the present invention is to provide various useful optical components and other articles or materials by applying the above low birefringence optical resin material.

[0014]

The low birefringence optical resin material of the present invention is obtained by subjecting a transparent polymer resin material mixed with molecular orientation suppressing particles having a size smaller than the wavelength of light to an orientation treatment. In other words, the molecular orientation suppressing particles are characterized by being formed of particles having a polarization isotropic property or particles having a shape isotropic property. Here, as the molecular orientation suppressing particles, those having higher hardness than the polymer resin material in the orientation treatment are used. As the molecular orientation suppressing particles, particles of an inorganic compound can be used. On the other hand, as the polymer resin material, a ring-opened polymer of a norbornene derivative can be used.

The method for producing a low birefringence optical resin material according to the present invention is characterized in that it comprises a step of mixing molecular orientation suppressing particles into a polymerizable material which produces a polymer resin material having transparency by a polymerization reaction. And The method for producing a low birefringence optical resin material of the present invention can be a method having a step of kneading molecular orientation suppressing particles in a transparent polymer resin material. Further, the method for producing a low birefringence optical resin material of the present invention can be a method having a step of mixing molecular orientation suppressing particles into a solution of a transparent polymer resin material. Further, the method for producing a low birefringence optical resin material of the present invention can be a method having a step of stretching a transparent polymer resin material mixed with molecular orientation suppressing granules.

An optical component according to the present invention is made of the above-mentioned low birefringence optical resin material. An optical apparatus according to the present invention is characterized in that the above optical component is used as an optical element. The adhesive for optical components of the present invention is made of the above-mentioned low birefringence optical resin material, and is used for joining optical components or optical elements.

The substrate for a liquid crystal element of the present invention is made of the above-mentioned low birefringence optical resin material, and is characterized by being interposed between the liquid crystal layer and the polarizing plate in the liquid crystal element. A polarizing plate for a liquid crystal element of the present invention is characterized in that a sheet made of the above-mentioned low birefringence optical resin material is bonded to both surfaces of a polarizer for a liquid crystal element. The adhesive for a liquid crystal element of the present invention is made of the above-mentioned low birefringence optical resin material, and is used for joining elements forming a liquid crystal element. The optical disc of the present invention is characterized in that the polymer resin material is made of the above-mentioned low birefringence optical resin material in which the polymer resin material is a ring-opening polymer of a norbornene derivative.

[0018]

According to the above arrangement, even if the polymer resin material constituting the matrix is a material which exhibits birefringence by itself, a state in which the molecular orientation suppressing particles satisfying specific conditions are mixed. By performing the orientation treatment, the degree of orientation of the polymer chains in the polymer resin material is suppressed, and as a result, the degree of birefringence developed is suppressed,
An optical resin material with reduced birefringence is obtained. And, because the optical resin material has low birefringence,
By forming various optical parts and optical products, good performance can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The low birefringence optical resin material of the present invention is obtained by subjecting a resin composition obtained by mixing molecular orientation suppressing particles to a transparent polymer resin material to an orientation treatment. It is something that can be done. In the present invention, the polymer resin material constituting the matrix of the optical resin material basically has transparency necessary for use as the intended optical resin material, and has other necessary characteristics. if there is,
There is no particular limitation, and any polymer resin material may be used. On the other hand, the molecular orientation suppressing granules mixed into the polymer resin material need to have a size smaller than the size of the wavelength of the applied light, and are made of a substance having isotropic properties with respect to polarization. It is necessary that the particles be granules or have isotropic shape.

The low birefringence optical resin material of the present invention is obtained by subjecting a polymer resin material constituting a matrix to an orientation treatment in a state where particles for suppressing molecular orientation are dispersed therein. As a result, the polymer chains of the polymer resin material are oriented in a specific direction. Here, the orientation treatment can be performed, for example, by applying an external force in a specific direction by a suitable molding treatment, a processing treatment such as a stretching treatment, and the polymer chains of the polymer resin material are oriented in a specific direction. Any method may be used, and the specific means is not limited.

In the optical resin material of the above-described embodiment, when the polymer chains are oriented, the presence of the molecular orientation suppressing particles hinders a part of the orientation of the polymer chains and reduces the degree of the orientation. As a result, the birefringence that is exhibited is reduced as compared with the case where the orientation treatment is performed in a state where no such molecular orientation suppressing granules are present.

The molecular orientation-suppressing particles mixed into the polymer resin material are as follows: (1) The size of the molecular orientation-suppressing particles is smaller than the wavelength of light; Having a size that does not cause scattering that substantially lowers the transparency of the material, and (2) a particle made of a substance having isotropic properties with respect to polarization, or having isotropic properties with respect to shape It is necessary to be granular.

When the powder mixed with the polymer resin material is a particle made of a substance having anisotropy with respect to polarization or a particle having anisotropy with respect to shape, the polymer resin material is oriented. In some cases, the birefringence exhibited by the treatment cannot be effectively reduced. In the above, the shape isotropy is such that if the grains have anisotropy with respect to polarization, the shape is such that no regular orientation is generated so as to express the polarization anisotropy as a whole. Means isotropic. Typical examples of such isotropic shapes are spheres and regular polygons.

The wavelength of light related to the size of the molecular orientation suppressing particles may be considered with reference to the wavelength of light applied to an optical device in which the obtained optical resin material is used. When light is used, the size of the molecular orientation suppressing particles needs to be several hundred nanometers or less. In fact, granules of such a size level are relatively easy to obtain. In addition, it is possible to easily obtain particles having isotropic properties with respect to polarization and particles having isotropic properties with respect to shape. Moreover, such granules can be applied as molecular orientation suppressing granules to virtually any polymer resin, and therefore, the freedom of choice of the polymer resin used for the optical resin material of the present invention is increased. The degree is extremely large. In addition, such particles do not substantially affect optical properties other than birefringence of the polymer resin, and have little effect on mechanical properties and the like.

As will be understood from the above description, the present invention provides a polymer resin material which forms a matrix by adding a certain substance to the polymer resin material. In terms of reducing or compensating for birefringence, it is similar to the prior art, but the mechanism for reducing the orientation birefringence of such a polymer resin material is completely different. In other words, in the prior art, utilizing the fact that the added low-molecular substance exhibits birefringence having a sign opposite to that of the orientation birefringence of the polymer resin material, the low-molecular substance as a whole is canceled out by the two. Although birefringence or low anisotropy is achieved, in the present invention, the degree of orientation is suppressed in the orientation treatment of the polymer resin material.

In the present invention, the polymer resin material for forming the matrix is required to have a certain degree of transparency for use as an optical resin material.
This polymer resin material is basically not particularly limited by the relationship with the molecular orientation suppressing particles mixed therein, and thus the degree of freedom in selecting the polymer resin material is extremely large. In fact, it is preferable to use a polymer resin material having general suitability as an optical resin material, and particularly suitable properties according to specific applications, such as excellent heat resistance and mechanical strength. It is preferable to use those having. The degree of transparency required for this polymer resin material is determined by the intended use of the optical component or the like, or the required optical characteristics, and is not particularly limited. The sign of the birefringence of the polymer resin material itself may be positive or negative.

Specific examples of the polymer resin material used in the present invention include polyolefins such as polyethylene and polypropylene, aromatic vinyl polymers such as polystyrene, poly (meth) acrylates such as polymethyl methacrylate, and polyphenylene. Oxides, polycarbonates, polyvinyl chloride, polyethylene terephthalate, polyarylate, polyethersulfone, polyethylene naphthalate, polymethylpentene-1, alicyclic polyolefins (for example, cyclic compounds such as dicyclopentadiene-based polyolefins and norbornene-based polyolefins) Ring-opening (co) polymers of olefins, hydrogenated (co) polymers thereof, saturated copolymers of cyclic olefins with unsaturated double bond-containing compounds, etc.), for example, tricyclodecanylamine Copolymers of alicyclic (meth) acrylates such as acrylate, cyclohexyl methacrylate and isobornyl methacrylate with (meth) acrylates such as methyl methacrylate, polysulfone, polyetherimide, amorphous polyamide, polyphenylene ether, and Examples include a hydrogenated polymer of a cyclic olefin, cyclopentadiene, a cationic (co) polymer of an aromatic vinyl compound, and the like. Among them, those having preferable optical characteristics include, for example, polymethyl methacrylate, certain polycarbonates, and alicyclic polyolefin-based polymers.

Of the above polymer resin materials, a polymer having a high degree of orientation birefringence alone requires the addition of a large amount of particles for suppressing molecular orientation, and as a result, the resulting optical resin material May be reduced in transparency. However, the alicyclic polyolefin-based polymer is usually a polymer having a small positive birefringence, so the amount of the molecular orientation suppressing particles to be mixed may be small, and therefore, high transparency,
An optical resin material having low birefringence in addition to heat resistance can be obtained, which is very preferable.

Preferred examples of the alicyclic polyolefin-based polymer include those obtained by ring-opening polymerization of a monomer comprising a norbornene derivative represented by the following general formula (1) or this monomer and a copolymerizable monomer copolymerizable therewith. And a hydrogenated polymer obtained by further hydrogenating such a ring-opened polymer. The ring-opening polymerization reaction of such a monomer is usually performed with a metathesis polymerization catalyst.

[0030]

Embedded image Wherein A and B are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X and Y each represent a hydrogen atom or a monovalent organic group, and m is 0 or 1. ]

In such a monomer having a norbornene ring, X or Y in the general formula (1) is represented by the formula
The monomer which is a carboxylic acid ester group represented by (CH ₂ ) _n COOR ¹ is preferable in that the obtained ring-opened polymer has a high glass transition temperature and a low hygroscopicity. One polar substituent group consisting of a carboxylic acid ester group is contained per one molecule of the monomer,
This is preferred in that the resulting ring-opened polymer has low hygroscopicity.

Further, among the carboxylic acid ester groups represented by the formula — (CH ₂ ) _n COOR ¹ , the smaller the value of n, the higher the glass transition temperature of the obtained ring-opened polymer. Is preferred because the synthesis is easy and the obtained ring-opened polymer has good properties. In the above formula, R ¹
Is a hydrocarbon group having 1 to 20 carbon atoms, but it is preferable that as the number of carbon atoms increases, the hygroscopicity of the obtained polymer decreases. However, from the viewpoint of the balance with the glass transition temperature of the obtained polymer, a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms is preferable, and a methyl group is particularly preferable. It is preferred that Further, a monomer in which a hydrocarbon group having 1 to 10 carbon atoms is simultaneously bonded as a substituent to a carbon atom to which a carboxylic acid ester group is bonded has a hygroscopic property without lowering the glass transition temperature of the obtained polymer. It is preferable because it lowers it. In particular, a monomer in which the substituent is a methyl group is preferable because its synthesis is easy. Among the above monomers, a tetracyclododecene derivative in which m is 1 in the general formula (1) is preferable in that a polymer having a high glass transition point can be obtained.

[0033] Among the compounds represented by the above general formula (1), examples of preferred compounds, 8-carboxymethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-carboxymethyltetracyclo [4.4.
0.1 ^2,5 .1 ^7,10] -3-dodecene, 5-carboxymethyl - bicyclo [2.2.1] -2-heptene, and the like.

The above-mentioned monomer can be subjected to ring-opening copolymerization with a monomer copolymerizable therewith, and such a copolymer can also be used. When the above-mentioned ring-opened polymer is hydrogenated, the hydrogenation rate is preferably high, at least 90 mol% or more, particularly 100 mol% or more.
Desirably, it is mol%. The molecular weight of the ring-opened polymer or a hydrogenated polymer thereof is preferably 20,000 to 500,000 in terms of polystyrene equivalent weight average molecular weight.

In the present invention, the molecular orientation suppressing particles can be freely selected from a wide range of materials as long as the particles satisfy the above conditions. The size of the molecular orientation suppression particles, as described above, may be a size smaller than the wavelength of light applied to the optical component or optical element by the optical resin material, for example, when the light is visible light Is a size of several hundred nanometers or less, for example, 50 to 300 n
m. When the applied light is a laser beam, a molecular orientation suppressing particle having a size corresponding to the wavelength may be used. When the size of the molecular orientation suppressing particles is excessively large, the obtained optical resin material has reduced transparency due to the presence of the molecular orientation suppressing particles.

The molecular orientation suppressing particles are made of a substance having an isotropic property with respect to polarization, or a particle having an isotropic property with respect to the shape when the material is made of a substance having no isotropic property with respect to polarization. It is necessary to be.

On the other hand, the particles having isotropic shape are typically those having an isotropic shape such as a sphere or a regular polygon, but are substantially isotropic. The shape may be any shape as long as the ratio of the minor axis to the major axis is, for example, 1/10 or more.

In the present invention, it is necessary that the powder used as the molecular orientation suppressing granules has a higher hardness than the polymer resin material in the orientation treatment. As a result of the orientation of the polymer chains of the material being inhibited by the mixed molecular orientation suppressing granules, the degree of orientation of the polymer chains due to the orientation treatment is suppressed as a whole.

In the present invention, the powder preferable as the molecular orientation suppressing particles is a powder of an inorganic compound, and specific examples thereof include various oxides, nitrides, carbides, fluorides and the like. However, those which are chemically stable are preferred. Specific examples of preferred granular materials include, for example, silica, aluminum oxide, titanium oxide, iron oxide, cerium oxide, yttrium oxide, manganese oxide, zirconium oxide, cobalt blue, indium oxide, magnesium oxide, neodymium oxide, and holmium oxide. Granules of an inorganic compound such as copper oxide and a composite oxide of aluminum oxide and magnesium oxide can be given. These inorganic compounds can be used as granules having a size smaller than the wavelength of light, and granules having an isotropic shape can be obtained.

It is also possible to use a powder composed of certain organic compound or polymer particles. Specific examples of such a substance include, for example, adamantane and dendrimer.

The mixing ratio of the particles for suppressing molecular orientation to the polymer resin material is not particularly limited as long as it is a ratio effective for reducing the orientation birefringence of the polymer resin material. 0.001 to polymer resin material
20 mass%, preferably in the range of 0.01 to 10 mass%. The mixing ratio of the molecular orientation suppressing particles is desirably small as long as the intended effect is obtained. If the mixing ratio of the molecular alignment suppressing particles is high, the transparency and mechanical strength of the obtained optical resin material are high. There is a possibility that the intrinsic properties of the polymer resin material, such as heat resistance, may be reduced.

In order to produce the low birefringence optical resin material of the present invention, a monomer or a composition thereof which produces a transparent polymer resin by a polymerization reaction is prepared, and the polymerization reaction of the polymerizable material is carried out. Incorporate the molecular orientation suppressing granules at the stage before starting, sufficiently disperse, an appropriate polymerization initiator,
After the addition of a chain transfer agent or the like, a method of initiating and proceeding the polymerization reaction by supplying energy such as heating or ultraviolet irradiation can be employed.

Here, the type and amount of the polymerization initiator and the chain transfer agent may be selected according to the same criteria as in the case of the ordinary polymerization reaction. For example, in the case of thermal polymerization, a peroxide such as benzoyl peroxide can be used as a thermal polymerization initiator. In the case of ultraviolet irradiation, benzoin methyl ether or the like, which is an ultraviolet radical polymerization initiator, can be used. In any case, normal butyl mercaptan or the like can be used as the chain transfer agent. According to this production method, it is advantageous in that the completion of the polymerization reaction allows the direct production of the polymer resin mixed with the molecular orientation suppressing granules.

Further, at the stage after the initiation of the polymerization reaction of the monomer or the composition thereof which forms the polymer resin and before the completion thereof, that is, the polymerization in a state where the polymerization reaction has been performed to some extent and the polymerizable oligomer is present. A method may be used in which the molecular orientation suppressing granules are mixed into the reaction system and sufficiently dispersed, and then the polymerization reaction is completed. Also in this production method, the completion of the polymerization reaction enables the direct production of a polymer resin material mixed with the molecular orientation suppressing granules.

In the above method, the molecular orientation suppressing particles are subjected to a surface treatment in advance with a surface treating agent (binder) having a high affinity for the monomer or its composition or the produced polymer resin. It is preferable that the dispersibility of the molecular orientation-suppressing particles in the polymer resin constituting the matrix can be increased. The treatment with this surface treatment agent can be performed as a series of steps together with the polymerization reaction.

Further, in the present invention, a polymer resin material having transparency is produced by a polymerization reaction, and this is heated and melted, and the molecular orientation suppressing granules are added thereto and kneaded, whereby the polymer resin material is kneaded. It is possible to produce a low birefringence optical resin material in which the molecular orientation suppressing particles are uniformly dispersed in the material.

Alternatively, a method of dissolving the polymer resin material in an appropriate solvent, adding the molecular orientation suppressing granules to a solution obtained and uniformly dispersing the resultant, and then removing the solvent by an evaporation treatment or the like, may be used. The desired optical resin material can be manufactured. According to the method of mixing the molecular orientation suppressing particles into the solution of the polymer resin material, it is easy to sufficiently disperse the molecular orientation suppressing particles in the form of fine powder, and furthermore, the polymer resin Since there is no need to heat the material, thermal degradation does not occur, and the optical properties and mechanical properties of the polymer resin material are not impaired. can get. Further, the solution in which the molecular orientation suppressing granules are dispersed can be used as it is for production of a product such as a film. Also in these methods, it is preferable to use the particles which have been subjected to a surface treatment with an appropriate surface treatment agent in advance as the molecular orientation suppressing particles.

The optical resin material mixed with the molecular orientation suppressing particles obtained by the above method usually shows birefringence as it is because the polymer chains of the polymer resin are not oriented. Not something. The optical resin material in which the molecular orientation suppressing particles are mixed is used as a raw material for various optical components and optical materials. In order to be ready for production, it is preferable to pelletize by an appropriate means. The pelletized optical resin material is molded into a desired shape by a normal molding technique excellent in mass productivity, such as injection molding or extrusion molding, to obtain a product.

In the matrix of the polymer resin forming such a molded product, the polymer chains are oriented in a specific direction by the action of an external force in the molding step, and the like.
Therefore, the orientation birefringence occurs, but in the course of this orientation, the molecular orientation suppressing granules mixed in the polymer resin material exhibit the effect of inhibiting the orientation of the polymer chains of the polymer resin, The birefringence of the polymer resin material to be developed by the alignment treatment is reduced, and the birefringence of the optical resin material as a whole becomes considerably smaller than in the case where the molecular orientation suppressing granules are not contained. .

For example, in the injection molding step, a high shear stress is generated in the polymer resin near the wall surface of the mold or near the gate of the mold, so that the orientation of the polymer chains is generated. In the extrusion molding step, Although the polymer chains of the polymer resin are oriented during extrusion or take-off, the degree of orientation of these polymer chains is suppressed, and the resulting birefringence is small. Also, when a film made of a polymer resin material mixed with molecular orientation suppressing granules is stretched, the orientation of the polymer chains of the polymer resin occurs. Although birefringence is developed, the resulting stretched film has low birefringence due to the inclusion of the molecular orientation suppressing particles.

That is, the molded optical resin material and the stretched optical resin material obtained as described above are:
The birefringence is extremely low, and the degree varies depending on the content ratio of the molecular orientation suppressing granules, the degree of orientation of the polymer chains, and other conditions. In some cases. In this specification, the term “low birefringence” simply includes the case of non-birefringence.

The optical resin material according to the present invention as described above can be used as a material for various optical parts by utilizing the above characteristics, and these optical parts can be used for various optical devices. . More specifically, the optical resin material according to the present invention has high utility especially as a member for a liquid crystal element. A specific example thereof is, for example, a liquid crystal element substrate arranged so as to be interposed between a liquid crystal layer and a polarizing plate. That is, the substrate formed of the optical resin material according to the present invention can be sufficiently used as a liquid crystal element substrate because it has no or low birefringence. When compared, the advantage of being an optical resin material is effectively utilized, and a liquid crystal device having good performance can be advantageously provided.

A polarizing plate for a liquid crystal element is formed by bonding transparent resin sheets to both surfaces of a polarizer. As the transparent resin sheet, a sheet made of the optical resin material according to the present invention can be used. As in the case of the liquid crystal element substrate, a liquid crystal device having good performance can be advantageously provided.

Further, the optical resin material according to the present invention can be used as an adhesive for adhering each component constituting the liquid crystal element. Such adhesives are preferred because of their low birefringence and in that they offer a great deal of freedom in the choice of component materials. That is, conventionally, since an adhesive made of a resin having a low birefringence is not provided, the bonding of each component is performed unless a certain degree of birefringence is allowed such as a monochrome type. Is performed using an adhesive, but as an alternative to this adhesive, an adhesive made of the optical resin material according to the present invention can be used, thereby improving the performance of the liquid crystal element in terms of durability and heat resistance. Can be improved.

FIG. 3 is an explanatory sectional view showing an example of the configuration of the liquid crystal element. In this example, 10 is a liquid crystal layer, 11
a, 11b are substrates arranged above and below the liquid crystal layer, 12a,
12b is a polarizing plate arranged on the outer surface of each of the substrates 11a and 11b, and each of the polarizing plates 12a and 12b is
The transparent resin sheet 14 is joined to both surfaces of the polarizer 13. In a liquid crystal device having such a configuration,
The substrates 11a and 11b and the transparent resin sheet 14 can be formed of the optical resin material according to the present invention. In addition, for bonding the substrates 11a and 11b and the respective polarizing plates 12a and 12b, the optical resin material according to the present invention is used. An adhesive as a raw material can be used.

FIG. 4 is an explanatory sectional view showing another example of the structure of the liquid crystal element. In this example, 10 is a liquid crystal layer, 15
Reference numerals a and 15b denote substrates disposed above and below the liquid crystal layer, respectively, and the polarizing plates 16a and 16b correspond to the substrates 15a and 15b, respectively.
5b, a polarizer 13 disposed on the outer surface thereof, and a transparent resin sheet 14 bonded on the outer surface of the polarizer 13 are laminated. That is, each substrate 15
a and 15b also serve as the transparent resin sheet 14 on the liquid crystal layer 10 side in the configuration of FIG.
16b is integrated with each substrate 15a, 15b. Also in the liquid crystal element having such a configuration, the substrates 15a, 15
b and the transparent resin sheet 14 can be formed of the optical resin material according to the present invention.
An adhesive using the optical resin material according to the present invention as a raw material can be used.

Further, a ring-opened polymer obtained from the norbornene derivative represented by the above-mentioned general formula (1) or a hydrogenated polymer thereof is used as a polymer resin, and a mixture obtained by mixing the molecular orientation suppressing granules with the polymer is An optical resin material having high transparency, excellent heat resistance, and low birefringence, and is particularly advantageous for manufacturing optical disks.

[0058]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. <Example 1> In this example, methyl methacrylate was used as a polymer resin material, and substantially spherical silica fine powder "Aerosil R812" having an average particle diameter of about 7 nm (Nippon Aerosil) was used as molecular orientation suppressing particles. (stock)
Was added at a ratio of 0.1% by mass to the polymer to prepare a silica dispersion solution. Using this silica dispersion solution, the thickness after drying is 100 μm by a solution casting method.
Was produced. This is designated as Sample 1. A stretching temperature of 80 ° C. and a stretching speed of 8 m were applied to the film of Sample 1.
Under the conditions of m / min, uniaxial stretching was performed at various stretching ratios. For each of the obtained stretched films, the birefringence value was determined, and the absorption intensity of expansion and contraction of α-CH ₃ with respect to light having a wave number of 1388 cm ⁻¹ was measured by a polarized infrared dichroism method. The degree of each orientation was determined. FIG. 5 shows the relationship between the obtained birefringence value and the magnitude of the stretching ratio, and FIG. 6 shows the relationship between the degree of orientation and the magnitude of the stretching ratio.

<Example 2> The addition ratio of the silica fine powder "Aerosil R812" as the molecular orientation suppressing granules was 2.0.
Except having changed to mass%, it carried out similarly to Example 1, and
A film having a thickness of 100 μm was produced. This is sample 2
And The film of Sample 2 was subjected to uniaxial stretching at various stretching ratios in exactly the same manner as in Example 1.
Each birefringence value and degree of orientation were determined. FIG. 5 shows the relationship between the obtained birefringence value and the magnitude of the stretching ratio, and FIG. 6 shows the relationship between the degree of orientation and the magnitude of the stretching ratio.

Comparative Example 1 A reference film having a thickness of 100 μm was prepared in the same manner as in Example 1 except that fine silica powder as molecular orientation suppressing particles was not added.
This is designated as Comparative Sample 1. The film of Comparative Sample 1 was uniaxially stretched at various stretching ratios in exactly the same manner as in Example 1, and the birefringence value and degree of orientation were determined. FIG. 5 shows the relationship between the obtained birefringence value and the magnitude of the stretching ratio, and FIG. 6 shows the relationship between the degree of orientation and the magnitude of the stretching ratio.

From the results shown in FIGS. 5 and 6, it is clear that the presence of the silica fine powder in the orientation treatment of the polymer resin material reduces the degree of birefringence exhibited. .

Example 3 8-methyl-8-carboxymethyltetracyclo [4. represented by the following structural formula (1)]
4.0.1 ^{2,5.1 7,10} ] -3-dodecene (250 parts by mass) and 1
-41 parts by weight of hexene and 750 parts by weight of toluene,
The reaction vessel was charged with nitrogen gas and heated to 60 ° C. To this, triethylaluminum (1.5 mol /
l) of a toluene solution of 0.62 parts by mass and a tungsten hexachloride solution modified with t-butanol / methanol (concentration: 0.05 mol / l, t-butanol: methanol: tungsten = 0.35: 0.3: 1) ) 3.7 parts by mass as a catalyst, and heated and stirred at 80 ° C for 3 hours,
A ring-opened polymer solution (a) was obtained. The polymerization conversion in this polymerization reaction was 97%. Further, the intrinsic viscosity (η _inh ) of the obtained polymer was 0.45 dl / g (in chloroform, at 30 ° C., and the concentration was 0.5 g / dl).

[0063]

Embedded image

4,000 parts by mass of the ring-opening polymer solution (a) thus obtained was placed in an autoclave, a hydrogenation catalyst was added thereto, and a hydrogen gas pressure of 100 kg / c was added.
Heating was performed for 3 hours under the conditions of m ² and a reaction temperature of 165 ° C. to perform hydrogenation. The hydrogenated polymer thus obtained was poured into a large amount of methanol to solidify the polymer. The hydrogenation rate of the hydrogenated polymer obtained here is substantially 100 mol%.
Met.

The above hydrogenated polymer was used as a polymer resin material, and the same molecular orientation suppressing particles as those used in Example 1 were added to the toluene solution in an amount of 0.2% to the polymer.
A silica dispersion solution was prepared by adding at a ratio of mass%.
Using this silica dispersion solution, a film having a thickness of 100 μm after drying was produced in the same manner as in Example 1, and it was recognized that this film had the same characteristics as Sample 1 of Example 1. Was done.

[0066]

According to the present invention, even if the polymer resin material constituting the matrix alone exhibits birefringence, the molecular orientation suppressing particles satisfying the specific conditions are mixed. By the orientation treatment in the state, the degree of orientation of the polymer chains in the polymer resin material is suppressed,
As a result, the degree of birefringence that is exhibited is suppressed, and as a result, an optical resin material with reduced birefringence is obtained.
Then, since the optical resin material has low birefringence, good performance can be obtained by forming various optical components and optical products.

The polymer resin is basically not subject to any restrictions. Therefore, even if the birefringence sign of the polymer resin itself is positive or negative, a low birefringence optical resin material is surely used. Can be provided. Further, as a result, the polymer resin can be freely selected from a wide range, so that the optical resin material having low birefringence using a polymer resin having suitable characteristics according to the intended use. Therefore, it is possible to advantageously provide, for example, a low birefringence optical resin material having excellent optical properties, mechanical properties, or particularly high heat resistance.

Further, by using the low birefringence optical resin material of the present invention, various optical parts having low birefringence can be formed, and devices including optical elements affected by birefringence, such as liquid crystal The components of the device can be advantageously provided, and various performances can be improved.

[Brief description of the drawings]

FIG. 1 shows the state of oriented polymer chains of a polymer resin,
It is explanatory drawing about the birefringence which is exhibited.

FIG. 2 is an explanatory diagram of a refractive index ellipsoid.

FIG. 3 is an explanatory cross-sectional view illustrating an example of a configuration of a liquid crystal element.

FIG. 4 is an explanatory cross-sectional view illustrating another configuration example of the liquid crystal element.

FIG. 5 is a graph showing the relationship between the birefringence value and the magnitude of the draw ratio for the samples of Examples and Comparative Examples of the present invention.

FIG. 6 is a graph showing the relationship between the degree of orientation and the magnitude of the draw ratio for the samples of Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coupling unit 2 Elliptical mark 3 Refractive index ellipsoid 10 Liquid crystal layer 11a, 11b Substrate 12a, 12b Polarizer 13 Polarizer 14 Transparent resin sheet 15a, 15b Substrate 16a, 16b Polarizer

Claims (15)

[Claims] 1. A transparent polymer resin material mixed with molecular orientation suppressing particles having a size smaller than the wavelength of light is subjected to an orientation treatment, and the molecular orientation suppressing particles have an isotropic property with respect to polarization. A low birefringence optical resin material, characterized in that it is made of a particle made of a substance or a particle having an isotropic shape. 2. The low birefringence optical resin material according to claim 1, wherein the molecular orientation suppressing particles have higher hardness than the polymer resin material in the alignment treatment. 3. The low birefringence optical resin material according to claim 1, wherein the molecular orientation suppressing particles are particles of an inorganic compound. 4. The low birefringence optical resin material according to claim 1, wherein the polymer resin material is a ring-opened polymer of a norbornene derivative. 5. A method for producing a low birefringence optical resin material according to claim 1, wherein the polymerizable material produces a transparent polymer resin material by a polymerization reaction. A method for producing a low-birefringence optical resin material, comprising a step of mixing molecular orientation-suppressing particles into the composition. 6. The method for producing a low birefringence optical resin material according to claim 1, wherein the molecular orientation suppressing particles are kneaded in a transparent polymer resin material. A method for producing a low birefringence optical resin material, comprising: 7. The method for producing a low birefringence optical resin material according to claim 1, wherein the molecular orientation-suppressing particles are contained in a solution of a polymer resin material having transparency. A method for producing a low birefringence optical resin material, comprising: 8. A method for producing a low birefringence optical resin material according to any one of claims 1 to 4, wherein the polymer resin material has transparency in which particles for suppressing molecular orientation are mixed. A method for producing a low-birefringence optical resin material, comprising a step of stretching. 9. An optical component comprising the low birefringence optical resin material according to claim 1. Description: 10. An optical apparatus using the optical component according to claim 9 as an optical element. 11. An adhesive for an optical component, comprising the low birefringence optical resin material according to claim 1 and used for bonding an optical component or an optical element. 12. A liquid crystal device comprising the low birefringence optical resin material according to claim 1 and interposed between a liquid crystal layer and a polarizing plate in the liquid crystal device. Substrate. 13. A sheet comprising the low birefringence optical resin material according to claim 1 and joined to both surfaces of a polarizer for a liquid crystal element. Polarizing plate for liquid crystal element. 14. An adhesive for a liquid crystal element, comprising the low birefringence optical resin material according to claim 1 and used for joining components forming a liquid crystal element. . 15. An optical disk comprising the low birefringence optical resin material according to claim 4.