JP2006258940A - Optical material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical material which is composed of a polytrimethylene terephthalate based resin and of which the birefringence is adjusted. <P>SOLUTION: The invention comprises: (1) the optical material which is composed of the polytrimethylene terephthalate based resin; (2) the optical material of (1) which is characterized by being stretched; (3) the resin of which the slope K obtained by least squares approximation satisfies an equation and an inequality shown below as follows, K=Δn(S)/S, 5.0×10<SP>-5</SP><K, in relation to the birefringence (Δn(S)) and a stretching ratio (S) in the case the polytrimethylene terephthalate based resin is stretched; (4) the optical material of (1) to (3) formed into a film or a sheet with extrusion; and (5) the optical material of (1) to (4) with birefringence of 0.002 or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical material having excellent optical characteristics.

Recently, with the expansion of the display market, there has been an increasing demand for clearer images, and there is a need for optical materials with higher optical properties than simple transparent materials. In general, a polymer has birefringence because its refractive index is different between the direction of the molecular main chain and the direction perpendicular thereto. Depending on the application, it is required to strictly control this birefringence, and a quarter-wave plate having a function of changing light polarized by a polarizing plate into circularly polarized light is consciously applied to a polymer material molded body. The function is given by generating birefringence.
In recent years, optical communication systems have become widespread, and the demand for optical devices used for broadband and high-speed communication is increasing. For example, in an arrayed waveguide diffraction grating (AWG) that is a planar lightwave circuit (PLC), a wave plate is inserted into the optical waveguide in order to solve the polarization dependence. At this time, in order to reduce the generated radiation loss as much as possible, it is desirable to reduce the thickness of the wave plate and narrow the gap width, and there is a demand for a material having a small thickness and a large in-plane birefringence.

As described above, an optical material having controlled birefringence and excellent thickness uniformity and transparency has been demanded.
On the other hand, Patent Document 1 discloses a film made of polytrimethylene terephthalate resin as a film having excellent thickness uniformity and transparency. However, there was no description or suggestion that polytrimethylene terephthalate resin is suitably used as an optical material.
JP-A-11-156934

  An object of the present invention is to provide an optical material of a polytrimethylene terephthalate resin with controlled birefringence.

The present inventors have surprisingly found that a molded article made of a polytrimethylene terephthalate resin having controlled birefringence can be suitably used as an optical material, and has completed the present invention.
That is, the present invention
[1] An optical material comprising a polytrimethylene terephthalate resin,
[2] The optical material according to [1], which is stretched,
[3] Resin in which the value of the slope K obtained from the least square approximation in the relationship between the birefringence (Δn (S)) and the draw ratio (S) when the polytrimethylene terephthalate resin is drawn satisfies the following formula: The optical material according to [1] or [2], wherein
K = Δn (S) / S
5.0 × 10 ⁻⁵ <K
[4] The optical material according to any one of [1] to [3], which is a film or sheet formed by extrusion molding
[5] The optical material according to any one of [1] to [4], wherein the absolute value of birefringence is 0.002 or more,
It is.

  The present invention makes it possible to provide an optical material with controlled birefringence.

Hereinafter, the present invention will be specifically described.
The polytrimethylene terephthalate in the present invention is a polytrimethylene terephthalate polymerized using terephthalic acid as an acid component and trimethylene glycol (also referred to as 1,3-propanediol) as a glycol component (hereinafter abbreviated as PTT). May be.)
In addition to PTT, the PTT resin of the present invention is an aromatic dicarboxylic acid other than terephthalic acid, such as phthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, as long as it does not impair the purpose of the present invention. Diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylmethane dicarboxylic acid, diphenyl ketone dicarboxylic acid, diphenyl sulfone dicarboxylic acid and the like; aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid; fats such as cyclohexane dicarboxylic acid Cyclic dicarboxylic acid; using oxydicarboxylic acid such as ε-oxycaproic acid, hydroxybenzoic acid, hydroxyethoxybenzoic acid, etc., and glycol component, ethylene glycol, tetramethylene glycol, pentamethylene glycol, Hexamethylene glycol, octamethylene glycol, neopentyl glycol, cyclohexanedimethanol, xylylene glycol, diethylene glycol, polyoxyalkylene glycol, may be copolymerized with some hydroquinone.

The amount of copolymerization in the case of copolymerization is not particularly limited as long as it does not impair the purpose of the present invention, but is usually 20 mol% or less of the total acid component or 20 mol% or less of the total glycol component. It is preferable.
In addition, the above-described polyester component may be added to a branched component, for example, an acid having trifunctional or tetrafunctional ester-forming ability such as tricarballylic acid, trimesic acid, trimellitic acid, or glycerin, trimethylolpropane, pentaerythritol, etc. Alcohols having a functional or tetrafunctional ester-forming ability may be copolymerized, and in this case, the amount of these branching components is 1.0 mol% or less of the total acid component or the total glycol component, preferably 0.8. It is 5 mol% or less, More preferably, it is 0.3 mol% or less. Further, the PTT resin may be used in combination of two or more of these copolymer components.

The method for producing the PTT resin used in the present invention is not particularly limited. For example, JP-A-51-140992, JP-A-5-262862, JP-A-8-311177, etc. Can be obtained according to the methods described.
For example, terephthalic acid or an ester-forming derivative thereof (for example, a lower alkyl ester such as dimethyl ester or monomethyl ester) is reacted with trimethylene glycol or an ester-forming derivative thereof at a suitable temperature and time in the presence of a catalyst. Further, there is a method in which the glycol ester of terephthalic acid obtained is subjected to a polycondensation reaction to a desired degree of polymerization at a suitable temperature and time in the presence of a catalyst.
The polymerization method is not particularly limited, and melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, and a combination thereof can be used.

The intrinsic viscosity [η] of the polytrimethylene terephthalate resin of the present invention is preferably 0.60 dl / g or more from the viewpoint of mechanical properties, particularly toughness, and [η] is 0.68 dl / g or more. More preferably, [η] is most preferably 0.75 dl / g or more from the viewpoint of moldability.
In the optical material of the present invention, the birefringence is preferably 0.002 or more. Birefringence (Δn) is described in various documents (for example, Chemical Review, No. 39, 1998 (published by Academic Publishing Center)). The absolute value of the birefringence of the optical material is more preferably 0.005 or more, and particularly preferably 0.01 or more.
In the production of the optical material of the present invention, in the relationship between the birefringence (Δn (S)) when stretched and the stretch ratio (S), the value of the slope K obtained from the least square approximation satisfies the following equation: Is preferably used.
K = Δn (S) / S
5.0 × 10 ⁻⁵ <K
The draw ratio (S) is a value represented by the following equation, where L0 is the distance between chucks before stretching and L1 is the distance between chucks after stretching.

The value of the slope K is more preferably 1.0 × 10 ⁻⁴ <K, and particularly preferably 2.0 × 10 ⁻⁴ <K. For example, when a film is used for a wave plate of an arrayed waveguide grating (AWG), a material having a K value in this range has a large change in birefringence due to stretching and orientation, and the film thickness is required to be as thin as possible. This is preferable because a sufficiently large birefringence can be obtained.
In the PTT resin of the present invention, a polymer other than polytrimethylene terephthalate can be mixed within a range that does not impair the object of the present invention. Polymers other than PTT include polyolefins such as polyethylene and polypropylene, styrene resins such as polystyrene and styrene acrylonitrile copolymer, polyamide, polyphenylene sulfide resin, polyether ether ketone resin, polyester, polysulfone, polyphenylene oxide, polyimide, poly At least one or more of thermoplastic resins such as ether imide and polyacetal, and thermosetting resins such as phenol resin, melamine resin, silicone resin, and epoxy resin can be further added.

  Furthermore, arbitrary additives can be mix | blended according to various objectives within the range which does not impair the effect of this invention remarkably. The type of additive is not particularly limited as long as it is generally used for blending resins and rubber-like polymers. Inorganic fillers, pigments such as iron oxide, stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bisstearamide, lubricants, mold release agents, paraffinic process oil, naphthenic process oil, Softeners and plasticizers such as aromatic process oil, paraffin, organic polysiloxane, mineral oil, hindered phenol antioxidants, antioxidants such as phosphorus heat stabilizers, hindered amine light stabilizers, benzotriazoles Examples include ultraviolet absorbers, flame retardants, antistatic agents, reinforcing agents such as organic fibers, glass fibers, carbon fibers, and metal whiskers, coloring agents, other additives, and mixtures thereof.

The method for producing an optical material in the present invention is not particularly limited, and a known method can be used. For example, it can be produced using a melt kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a Brabender, or various kneaders.
The optical material in the present invention can be molded by a known method such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, extrusion molding, foam molding, etc. Secondary processing and molding methods can also be used.
When the form of the optical material of the present invention is a film or a sheet, a preferable method is a method such as extrusion. For example, an unstretched film can be extruded by using an extruder equipped with a T die, a circular die, or the like. Further, after dissolving the polytrimethylene terephthalate resin using a solvent soluble in the polytrimethylene terephthalate resin, for example, a mixed solvent of chloroform and methylene dichloride, a solvent such as hexafluoroisopropanol, o-chlorophenol, etc. The optical material can also be cast by solidification by casting and solidifying.

  The film obtained by the above method can further be longitudinally uniaxially stretched in the mechanical flow direction, transversely uniaxially stretched in the direction orthogonal to the mechanical flow direction, and a sequential biaxial stretching method of roll stretching and tenter stretching, A biaxially stretched film can be produced by stretching by a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, or the like. The strength of the film can be improved by stretching. The final draw ratio can be determined from the heat shrinkage rate of the obtained molded body. The draw ratio is preferably 0.1% or more and 1000% or less in at least one direction, more preferably 0.2% or more and 600% or less, and more preferably 0.3% or more and 300% or less. Especially preferred. By designing in this range, a stretched optical material preferable in terms of birefringence, retardation, heat resistance, and strength can be obtained.

In the present invention, the difference between a film and a sheet is only the thickness, the film means a thickness of 300 μm or less, and the sheet has a thickness exceeding 300 μm. The thickness of the film is preferably in the range of 0.1 to 300 μm, more preferably in the range of 0.2 to 250 μm, and particularly preferably in the range of 0.3 to 200 μm. The sheet is desirably 10 mm or less, more desirably 5 mm or less.
The optical material of the present invention includes a polarizing plate protective film, a liquid crystal optical compensation film, a display front plate, a display substrate, a lens and the like used for a display such as a liquid crystal display, a plasma display, an organic EL display, a field emission display, and a rear projection television. An arrayed waveguide diffraction grating (AWG) which is a planar lightwave circuit (PLC), a wave plate used for the waveguide, a wavelength tunable filter, an optical switch, a flexible optical waveguide, and the like. The optical material of the present invention can be subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

Next, the present invention will be described by way of examples.
First, the evaluation methods used in the present invention and examples will be described.
(A) Evaluation.
(1) Measurement of birefringence
A birefringence measuring apparatus described in detail in Polymer Engineering and Science 1999, 39, 2349-2357 was used. The absolute value (| Δn |) of birefringence (Δn) was obtained as follows.
| Δn | = | nx−ny |
(2) Intrinsic Viscosity For the intrinsic viscosity [η], use an Ostwald viscometer so that the composition is solute (PTT resin component) /solution=1.00 g / dl in o-chlorophenol at 35 ° C. After being dissolved and insoluble matter (inorganic reinforcing material or the like) was precipitated, the specific viscosity ηsp was measured using the supernatant and determined by the following formula.
[Η] = 0.713 × ηsp / C + 0.1086
C = 1.00 g / dl

(B) Used raw materials, etc. (1) Polytrimethylene terephthalate resin (A-1)
A polytrimethylene terephthalate resin with [η] = 1.2 dl / g was used.
(2) Polycarbonate resin (B-1)
As the polycarbonate resin used for comparison, a polycarbonate resin having a melt flow rate of 10 g / 10 min (according to ASTM D1238, 300 ° C., load 1.2 kg) was used.

[Examples 1-5 and Comparative Examples 1-2]
The pellets of (A-1) or (B-1) were put into a hopper of a Technobel T-die mounting extruder (KZW15TW-25MG-NH type / width 150 mm T-die mounting / lip thickness 0.5 mm). By adjusting the resin temperature in the cylinder of the extruder and the temperature of the T-die and performing extrusion molding, uniaxial stretching (stretching speed 5% / min) of the obtained unstretched film was performed using a tensile tester. 5. The film of Comparative Examples 1-2 was obtained. Nx necessary for obtaining | Δn | = | nx−ny | is a refractive index in a uniaxial tensile direction, and ny is a refractive index in a direction perpendicular to the uniaxial tensile direction. Tables 1 and 2 show the composition, extrusion conditions, stretching conditions, film thickness, and absolute values of birefringence. Further, the relationship between birefringence (Δn (S)) and stretch ratio (S) obtained from the results of Tables 1 and 2 was plotted, and the value of K was obtained by least square approximation. The results are shown in Table 3. A graph showing the relationship between birefringence (Δn (S)) and draw ratio (S) is shown in FIG.

  The optical material of the present invention is an optical material that is transparent and has excellent optical properties in which birefringence is controlled, and is a polarizing plate used in displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, etc. Liquid crystal optical compensation film such as protective film, viewing angle control film, display front plate, display substrate, lens, etc., arrayed waveguide diffraction grating (AWG) which is a planar lightwave circuit (PLC), wavelength plate used for waveguide, variable wavelength Filters, optical switches, flexible optical waveguides.

It is a graph which shows the relationship of birefringence ((DELTA) n (S)) at the time of extending | stretching of an Example and a comparative example, and a draw ratio (S).

Claims (5)

  An optical material made of polytrimethylene terephthalate resin.   2. The optical material according to claim 1, wherein the optical material is stretched. In the relationship between birefringence (Δn (S)) and stretch ratio (S) when a polytrimethylene terephthalate resin is stretched, the value of the slope K obtained from the least square approximation is a resin that satisfies the following equation: The optical material according to claim 1 or 2.
K = Δn (S) / S
5.0 × 10 ⁻⁵ <K   The optical material according to any one of claims 1 to 3, wherein the optical material is a film or sheet formed by extrusion molding.   The optical material according to any one of claims 1 to 4, wherein an absolute value of birefringence is 0.002 or more.

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