TWI582123B - Norbornene-based optical anisotropic film and fabrication method for the same - Google Patents

Description

Norbornene optical anisotropic film and method of producing the same

The present invention relates to a norbornene optical anisotropic film and a method of producing the same.

Conventionally, inorganic glass has been commonly used in the field of optical materials including optical members such as lenses, liquid crystal display devices, color filters, display substrates such as electroluminescence display devices, backlights, light guides, and the like. However, inorganic glass has the latest trends such as fragility, lack of elasticity, high specific gravity, and poor processability, so that it cannot keep up with the latest trends of lighter weight, smaller and more compact.

In the use in optical materials, transparent resins are required to perform quite well in terms of heat resistance, chemical resistance, low absorbance, and the like. For example, in the fabrication of substrates for display devices, transparent resins are inevitably subjected to high temperature processing in the process of laminating metal or metal oxide films, but are also severely susceptible to heat or water absorption. The deformation of the substrate caused by the change in size.

First, the cellulose retardation film is now susceptible to great changes in the phase difference caused by water (ΔRo>5 nm, ΔRth>10 nm). Therefore, a film having high stability to water is required.

In particular, when the panel is driven by open cell bussiness, it is finally necessary to ensure the optical stability of the compensation film under high temperature and high humidity in the related art (ΔRo<1奈Meter, △Rth<1 nm).

For this reason, it has been proposed to add a cycloolefin-added polymer as a resin, that is, polynorbornene, to satisfy desired properties such as transparency, heat resistance, chemical resistance, low water absorption, and optical properties, and to use a cyclic olefin. A material for a liquid crystal display panel to which a polymer is added (refer to Patent Document 1).

The cyclic olefin-added polymer, particularly polynorbornene, is a material which has excellent resistance to thermal deformation of a high-temperature process due to its high glass transition temperature of about 250 ° C or higher. Furthermore, polynorbornene has extremely low water absorption, resulting in high dimensional stability against changes in humidity under use conditions, and a low linear elongation of about 55 ppm, thus having high dimensional stability for thermal changes.

However, a cyclic olefin-added polymer, polynorbornene, has a low dissolution rate for a general solvent, and thus it is impossible to form a film by a casting method. In other words, due to the addition of a polymer to a cyclic olefin, polynorbornene, which has a low dissolution rate for a general solvent, a cycloolefin-added polymer, polynorbornene, must be formed by a melt casting method. This has led to a deterioration in productivity. The reason is related to the fact that the melt casting method involves a lower line rate than the solvent casting method.

In order to overcome this problem, a method of using a norbornene compound which enhances the solubility in a solvent as an additional polymer has been developed (refer to Patent Document 2), but this method causes deterioration of drawability, and thus With There is a difficulty in reaching the amount of delay.

Related application [Application document]

[Patent Document 0001]: Japanese Patent Laid-Open Application No. H05-061026A (March 12, 1993).

[Patent Document 0002]: Korean Application No. 2008-0096577 (October 30, 2008).

It is an object of the present invention to provide a film comprising an additional polymer of a norbornene compound, the film of which is soluble in a general solvent to achieve high yield and to ensure high dimensional stability to water.

In order to solve the problems of the prior art, the present invention provides a norbornene optical anisotropic film comprising a norbornene resin comprising one of the repeating units represented by Chemical Formula 1:

Wherein R ₁ is hydrogen or a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethoxy group substituted by an alkoxy group having at least 4 carbon atoms. And m and n are each an integer of 1 or higher.

In the optical anisotropic film of the present invention, the repeating unit comprises a stretchability enhancing monomer B and a polymerizable enhancing monomer M. The stretchability enhancing monomer B comprises at least one of the group of monomers of the formula 2 or 3; and the polymerizable enhancing monomer M comprises a group of monomers selected from the chemical formula 4 or 5 At least one of:

In the optical anisotropic film of the present invention, the molar ratio of the copolymerizable monomer B to the copolymerization promoting monomer M is from 5.5:4.5 to 7.5:2.5.

In the optical anisotropic film of the present invention, the norbornene resin has an average molecular weight of from 350,000 to 600,000 g/mole.

In the optical anisotropic film of the present invention, the optical anisotropy film satisfies Rth/Ro 2.7.

In the optical anisotropic film of the present invention, when one sample of the full width film is stored in a water bath for one day, the optical anisotropy film has a retardation of ΔRo<1 nm and ΔRth<1 nm. The amount changes.

In the optical anisotropic film of the present invention, the optical anisotropic film has a stretchability of at least 120% at a thickness of 40 μm, an initial retardation amount (Rth) of 200 nm or less, and 30 nm. A pull-pull delay rate of /10% or less, a modulus of 1300 Newtons/nano square or more, and a photoelastic constant of 30x10 ^-12 square meters/Newton or less.

According to the present invention, there is also provided a method for producing an optically anisotropic film, comprising: (1) polymerizing a stretchability enhancing monomer B and a polymerizable reinforcing monomer M, in preparation for including the formula 1 One of the repeating units of norbornene resin; (2) dissolving the norbornene resin in a solvent, and casting the resulting solution into a film; and (3) pulling the film,

Wherein R ₁ is hydrogen or a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethoxy group substituted by an alkoxy group having at least 4 carbon atoms. And m and n are each an integer of 1 or more.

In the production method of the present invention, the solvent includes dichloromethane and methanol.

In the manufacturing method of the present invention, the norbornene in a solvent The resin has a solids content of 15 to 25 weight percent.

The effect of the invention:

The optically anisotropic film of the present invention can be dissolved in a general solvent, and thus high yield can be achieved and high dimensional stability to water can be ensured.

The invention will be described in detail below.

According to an aspect of the invention, there is provided an optical anisotropic film comprising a norbornene resin comprising one of the repeating units represented by the following Chemical Formula 1:

Wherein R ₁ is hydrogen or a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethoxy group substituted by an alkoxy group having at least 4 carbon atoms. And m and n are each an integer of 1 or higher.

This repeating unit includes one of the stretchability enhancing monomer B and a polymerizable enhancing monomer M as shown below:

The stretchability enhancing monomer B includes at least one selected from the group consisting of a plurality of monomers of the following Chemical Formula 2 or 3; and the polymerizable enhancing monomer M includes a plurality of the following Chemical Formula 4 or 5 At least one of the individual populations:

[Chemical Formula 4]

Preferably, the molecular weight of the norbornene resin is in the range of from 350,000 to 600,000 grams per mole. When the molecular weight is less than 350,000 gram/mol or more than 600,000 gram/mole, it may be difficult to control the process and the remaining solvent due to an increase or decrease in the solid content.

Preferably, the molar ratio of the copolymerizable monomer B to the copolymerization-enhancing monomer M is in the range of 5.5:4.5 to 7.5:2.5. When this Mohr fraction is within this definition, the film can achieve the properties required in the prior art.

In other words, Rth/Ro is satisfied in this optical anisotropic film. 2.7, and when one of the full width film samples is stored in a water bath for one day, the optical anisotropy film has a retardation change of ΔRo < 1 nm and ΔRth < 1 nm. Further, the optical anisotropic film has a stretchability of at least 120% at a thickness of 40 μm, an initial retardation amount (Rth) of 200 nm or less, a pull of 30 nm/10% or less - Push delay rate, modulus of 1300 Newtons/nano square or greater, and photoelastic constant (RT) of 30x10 ^-12 square meters/Newton.

According to another object of the present invention, there is provided a method for producing an optically anisotropic film, comprising: (1) polymerizing a stretchability enhancing monomer B and a polymerizable reinforcing monomer M to prepare to include One of the repeating units shown in Chemical Formula 1 is a norbornene resin; (2) dissolving the norbornene resin in a solvent, and casting the resulting solution into a film; and (3) pulling the film,

Wherein R ₁ is hydrogen or a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethoxy group substituted by an alkoxy group having at least 4 carbon atoms. And m and n are each an integer of 1 or more.

This solvent comprises dichloromethane and methanol, and the ratio of dichloromethane to methanol is in the range of from about 95:5 to 80:20.

Preferably, the norbornene resin in the solvent has a solids content of from 15 to 25 weight percent. When the solid content is about 15 to 25 weight percent, the film can exhibit a more controllable process and one of the remaining solvent doping target viscosity.

In the following, the invention will be explained in more detail with reference to a few embodiments, which are merely intended to be a detailed description of the invention and not to limit the scope of the invention.

[Examples]

Example 1 - BM5545

The stretchability enhancing monomer B and the polymerizable enhancing monomer M are copolymerized in accordance with a molar ratio of 5.5:4.5 (B:M). Next, the film was prepared at a humidity of 30% or less, and peeled off when the remaining solvent was substantially 0 weight percent.

The film was pulled at 185 ° C and dried at 70 ° C to finally produce a norbornene resin film.

Example 2 - BM6040

The procedure was carried out in the same manner as described in Example 1 to prepare a film in which the molar ratio of the monomer (B:M) was changed to 6:4 to synthesize the norbornene resin.

Example 3 - BM7030

The procedure was carried out in the same manner as described in Example 1 to prepare a film except that the molar ratio of the monomer (B:M) was changed to 7:3 to synthesize the norbornene resin.

Example 4 - BM7525

The procedure was carried out in the same manner as described in Example 1 to prepare a film except that the molar ratio of the monomer (B:M) was changed to 7.5:2.5 to synthesize the norbornene resin.

Comparative example

Comparative Example 1-BM1090

The procedure was carried out in the same manner as described in Example 1 to prepare a film in which the molar ratio of the monomer (B:M) was changed to 1:9 to synthesize the norbornene resin.

Comparative Example 2 - BM2080

The procedure was carried out in the same manner as described in Example 1 to prepare a film in which the molar ratio of the monomer (B:M) was changed to 2:8 to synthesize the norbornene resin.

Comparative Example 3 - BM8020

The procedure was carried out in the same manner as described in Example 1 to prepare a film in which the molar ratio of the monomer (B:M) was changed to 8:2 to synthesize the norbornene resin.

Experimental example:

The drawing processability, optical characteristics, physical properties, durability, and the like of the films prepared in Examples 1-4 and Comparative Examples 1-3 were measured. The relevant measurement methods are as follows.

Pullability evaluation: The damage was checked by unit pull (100%, 110%, 120%, 140%).

Haze: Use a haze meter.

Delay amount (Ro and Rth) measurements: using a polarimeter (Axo Scan).

Delay amount: A change in phase difference caused by unit pull (100%, 110%, 120%).

Modulus, tensile strength, and elongation: UTM is used.

Brittleness: sensory assessment

Photoelastic constant: Use a Cobra device. The weight per unit of film at a particular temperature.

Perform a measurement of Ro when changing.

Water stain: A change in the amount of retardation before and after immersion in water at room temperature.

Thermal expansion coefficient: TMA measurement.

The measurement results are shown in Table 1 below.

Table I

Claims (10)

A norbornene optical anisotropic film comprising: a norbornene resin comprising a repeating unit represented by Chemical Formula 1: Wherein R ₁ is a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethoxy group substituted by an alkoxy group having at least 4 carbon atoms; m and n are each an integer of 1 or higher. The norbornene optical anisotropic film according to claim 1, wherein the repeating unit comprises a stretchability enhancing monomer B and a polymerizable reinforcing monomer M, wherein the stretchability is improved. The monomer B includes at least one selected from the group consisting of a plurality of monomers of the chemical formula 2 or 3; and the polymerizable enhancing monomer M is represented by the chemical formula 5: [Chemical Formula 3] The norbornene optical anisotropic film according to claim 2, wherein a molar ratio of the stretchability enhancing monomer B to the copolymerization promoting monomer M is 5.5:4.5 to 7.5. :2.5. The norbornene optical anisotropic film according to claim 1, wherein the norbornene resin has an average molecular weight of from 350,000 to 600,000 g/mole. The norbornene optical anisotropic film according to claim 1, wherein the optical anisotropy film satisfies Rth/Ro<2.7. The norbornene optical anisotropic film according to claim 1, wherein the optical anisotropy film has ΔRo<1 nm when one sample of the full width film is stored in a water bath for one day. The amount of retardation of ΔRth < 1 nm changes. The norbornene optical anisotropic film according to claim 1, wherein the optical anisotropy film has an initial at least 120% stretchability, 200 nm or less at a thickness of 40 μm. Delay amount (Rth), pull-pull delay rate of 30 nm/10% or less, modulus of 1300 Newtons/nano square or more, and light of 30x10 ^-12 square meters/Newton or less Elastic constant (RT). A method for producing an optical anisotropic film, comprising: (1) polymerizing a stretchability enhancing monomer B and a polymerizable reinforcing monomer M to prepare a repeating unit comprising the chemical formula 1 shown below a norbornene resin; (2) dissolving the norbornene resin in a solvent, and casting the resulting solution into a film; and (3) pulling the film, Wherein R ₁ is a formazan group substituted by an alkoxy group having 1 to 2 carbon atoms, and R ₂ is a formazan group or an ethyl methoxy group substituted with an alkoxy group having at least 4 carbon atoms, and m and n are each an integer of 1 or more. The method for producing an optical anisotropic film according to claim 8, wherein the solvent comprises dichloromethane and methanol. The method for producing an optical anisotropic film according to claim 9, wherein the norbornene resin in the solvent has a solid content of 15 to 25 wt%.