WO2008066306A1

WO2008066306A1 - Norbornene polymer or copolymer and method of preparing the same

Info

Publication number: WO2008066306A1
Application number: PCT/KR2007/006022
Authority: WO
Inventors: Sang Wook Park; Soo Min Back; Heon Seung Chae; Min Joo Kang; Jong Min Park
Original assignee: Kolon Industries, Inc.
Priority date: 2006-11-27
Filing date: 2007-11-27
Publication date: 2008-06-05
Also published as: JP5187314B2; JP2010511073A; KR20080047687A; KR101175818B1

Abstract

Disclosed is a norbornene polymer or copolymer, which exhibits superior heat resistance and optical properties and is thus suitable for use as a material for heat- resistant optical parts and electronic parts. Also, a method of preparing the same is provided.

Description

[DESCRIPTION]

[invention Title]

NORBORNENE POLYMER OR COPOLYMER AND METHOD OF PREPARING THE SAME

[Technical Field]

The present invention relates to a norbornene polymer or copolymer and a method of preparing the same.

.Background Art]

A cyclic olefin polymer polymerized from a cyclic olefin monomer, such as norbornene, has superior transparency, heat resistance, and chemical resistance, and inferior birefringence and water absorption, to those of conventional olefin polymers. Thus, such a cyclic olefin polymer may be used for insulation films of semiconductors or TFT-LCDs, protective films of polarizers, multichip modules, integrated circuits (IC), printed circuit boards, sealants for electronic devices, or low-dielectric coating agents, films, and packages for flat panel displays or optical purposes, and may also be used as material for plastic substrates for flexible displays.

However, in order to serve for the above end uses, the norbornene polymer must be guaranteed to have high optical properties and thermal stability. Norbornene polymers that are commercially available at present have light transmittance of about 80-90% and a glass transition temperature (Tg) of 100~180^°C, and thus do not satisfy the requirements for the above end uses . In order to prepare the cyclic olefin polymer, addition polymerization through copolymerization with olefin, homogeneous polymerization using a metallocene catalyst, or norbornene polymerization using ROMP (Ring- opening Metathesis Polymerization) is conducted these days. In the case of addition polymerization through copolymerization with olefin, a homogeneous vanadium catalyst is used. However, this method is disadvantageous because the activity of the catalyst is low, oligomers are produced in large amounts, and heat resistance is not high. In the case of homogeneous polymerization using a zirconium-based metallocene catalyst, as the concentration of the cyclic monomer increases, the activity of the catalyst decreases and the glass transition temperature decreases. Further, the resuJ tant norbornene polymer has very high crystallinity, and undesirably, does not dissolve in a general organic solvent.

Also, attempts have been made to subject a norbornene polymer obtained through ROMP (Ring-opening Metathesis Polymerization) to hydrogenation in the presence of a Pd or Raney-Ni catalyst in order to prepare a stable backbone, but encountered problems in that thermal stability was decreased and the production cost was increased.

Further, in the case where the cyclic olefin monomer contains a polar functional group such as an ester group, the polar functional group is found to play a role in enhancing intermolecular packing and increasing adhesion to a metal substrate or another polymer, and is thus continuing to receive attention, but is problematic in that the optical properties and thermal stability thereof are not assured. Typically, a polymer composed of a monomer having a bulky structure has a tendency to have a decreased glass transition temperature, and has undesirable thermal stability problems, and thus is regarded as unsuitable for use as an electronic material. However, the present inventors determined that, when a ring-opened polymer is prepared from a norbornene monomer, into which a bulky substituent is introduced, the glass transition temperature is somewhat increased, and thus confirmed that an optical material including the same exhibits superior optical properties and thermal properties, thereby completing the present invention.

[Disclosure] [Technical Problem]

Accordingly, the present invention provides a norbornene polymer or copolymer having high heat resistance and good optical properties.

In addition, the present invention provides a method of preparing a norbornene polymer or copolymer that exhibits high heat resistance and increased light transmittance and refractive index.

In addition, the present invention provides an optical material having superior refractive index and light transmittance .

[Technical Solution] According to an embodiment of the present invention, a norbornene homopolymer or copolymer may include a repeating unit represented by Formula 1 below: Formula 1

wherein Ri, R₂ and R₃, which are the same as or different from each other, are a hydrogen atom, a Cχ~io linear or branched alkyl group, or a C₅~i₂ cyclic alkyl group, at least one of Ri, R₂ and R₃ not being a hydrogen atom, and R₄ is selected from among

and

, in which R₅ is a hydrogen atom, a Ci~i₀ linear or branched alkyl group, or a C_5^i₂ cyclic alkyl group; X is -CH=CH- or -CH₂CH₂-; and n is an integer of 0 or more.

In the above embodiment, the norbornene homopolymer or copolymer may have a weight average molecular weight of 15,000-600,000.

According to another embodiment of the present invention, a method of preparing a norbornene homopolymer or copolymer may include polymerizing a norbornene monomer represented by Formula 2 below in the presence of a metathesis polymerization catalyst:

Formula 2

wherein Ri, R₂ and R₃, which are the same as or different from each other, arej a hydrogen atom, a Ci~io linear or branched alkyl group, or a C₅-_I2 cyclic alkyl group, at least one of Ri, R₂ and R₃ not being a hydrogen

atom, and R₄ is selected from among

and

, in which R₅ is a hydrogen atom, a Ci~io linear or branched alkyl group, or a C₅~i₂ cyclic alkyl group; and n is an integer of 0 or more.

In the above embodiment, the metathesis polymerization catalyst may be a ruthenium-based catalyst. The method according to the above embodiment may further include subjecting a carbon-carbon double bond of the norbornene homopolymer or copolymer to hydrogenation in the presence of a hydrogenation catalyst.

According to a further embodiment of the present invention, an optical material may include the norbornene homopolymer or copolymer as above.

The optical material may have a refractive index of 1.5 or more and light transmittance of 0.9 or more, according to Equation 1 below: Equation 1

intensity of light incident perpendicular to a substrate

Ia. intensity of light absorbed by a substrate

intensity of light reflected from a substrate.

[Best Mode]

Hereinafter, a detailed description will be given of the present invention.

According to the present invention, the norbornene polymer, which is a homopolymer or copolymer including the repeating unit of Formula 1, is a ring-opened polymer of a cyclic norbornene monomer into which an ester group and a bulky substituent are introduced, and has a weight average molecular weight of 15,000-600,000 and a glass transition temperature (Tg) of 200~300°C.

The norbornene polymer of the present invention is polymerized from a monomer having the structure of Formula 2 in the presence of a metathesis polymerization catalyst, according to Reaction 1 below:

Reaction 1

wherein R₁, R₂ and R₃, which are the same as or different from each other, are a hydrogen atom, a Ci~io linear or branched alkyl group, or a C₅-.₁₂ cyclic alkyl group, at least one of Ri, R₂ and R₃ not being a hydrogen

atom, and R₄ is selected from among

and

, in which R₅ is a hydrogen atom, a C₁-V_1O linear or branched alkyl group, or a C₅~i₂ cyclic alkyl group; X is -CH=CH- or -CH₂CH₂-; and n is an integer of 0 or more. In Reaction 1, a ruthenium phenylidene catalyst

(Grubbs catalyst) is a type of metathesis polymerization catalyst useful for the preparation of the norbornene polymer of the present invention, but the present invention is not limited to the ruthenium phenylidene catalyst. Used in the present invention, the metathesis polymerization catalyst is a compound of a Group 4 to 8 transition metal of the periodic table, and may be an arbitrary catalyst for ROMP (Ring-opening Metathesis Polymerization) of the norbornene monomer of Formula 2. For example, a catalyst disclosed in "Olefin Metathesis and Metathesis Polymerization (K.J.Ivin and J. C. MoI, Academic Press, San Diego, 1997)' may be used. Examples of the metathesis polymerization catalyst include an ROMP catalyst composed of a combination of transition metal halide and a co-catalyst, a Group 4 to 8 transition metal-carbene complex catalyst, and a metallacyclobutane complex catalyst. These metathesis polymerization catalysts may be used alone or in combinations of two or more thereof. Among them, particularly useful is a Group 4 to 8 transition metal- carbene complex catalyst. Examples of the Group 4 to 8 transition metal-carbene complex catalyst include a tungsten-alkylidene complex catalyst, a molybdenum-alkylidene complex catalyst, a rhenium-alkylidene complex catalyst, and a ruthenium- carbene complex catalyst. In the present invention, particularly useful is a ruthenium-carbene complex catalyst, which is a ruthenium-based catalyst.

The ruthenium-carbene complex catalyst may be prepared through the process disclosed in Org. Lett., 1999, Vol.l, p953 and Tetrahedron Lett., 1999, Vol.40, p2247. In the present invention, the metathesis polymerization catalyst is used such that the molar ratio of the catalyst to the monomer is 1:100-1:2,000,000, and preferably 1:1,000-1:500,000. When the amount of catalyst exceeds the above molar ratio, it is difficult to remove the catalyst. On the other hand, when the amount of catalyst is less than the above molar ratio, polymerization activity is not sufficiently exhibited.

The ring-opening polymerization of the norbornene monomer using the metathesis polymerization catalyst may be performed in the presence or absence of a solvent in an inert gas atmosphere. The solvent is not particularly limited, as long as it dissolves the produced polymer and does not inhibit the polymerization reaction. Examples of the solvent include aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, nitrogen-containing hydrocarbons, ethers, ketones, and esters.

The concentration of the norbornene monomer in the solvent preferably ranges from 1 wt% to 50 wt%. When the concentration is less than 1 wt%, the productivity of the polymer may become poor. On the other hand, when the concentration exceeds 50 wt%, the resultant polymer has too high a viscosity and makes hydrogenation difficult.

The ring-opening polymerization is conducted at 0~100^°C for 1-20 hours, which may be appropriately adjusted depending on the extent of progress of the reaction.

The polymer thus prepared has a weight average molecular weight of 15,000-600,000 and a glass transition temperature (Tg) of 200-300 ^°C.

Further, the ring-opened norbornene polymer obtained through ring-opening polymerization may be subjected to hydrogenation. Through hydrogenation using hydrogen gas in the presence of a hydrogenation catalyst, the carbon-carbon double bond of the backbone of the ring-opened norbornene polymer may be converted into a saturated single bond.

The hydrogenation catalyst is not particularly limited, but examples thereof include a homogeneous catalyst, such as a Ziggler catalyst or a ruthenium-carbene complex catalyst, which is a combination of a transition metal compound and an alkali metal compound, or a heterogeneous catalyst obtained by supporting a metal, such as nickel, palladium, platinum, rhodium, or ruthenium, on a support such as carbon, silica, diatomite, alumina or titanium oxide. In this way, a catalyst generally used for the hydrogenation of the olefin compound may be appropriately used. The hydrogenation is typically conducted in the presence of an organic solvent. The type of organic solvent may be appropriately selected depending on the solubility of the resultant hydrogenation product. An organic solvent that is the same as the solvent for the polymerization may be used. Thus, after the polymerization reaction, hydrogenation is conducted in such a manner that the metathesis polymerization cataLyst is removed to thus obtain a filtrate to which the hydrogenation catalyst is then added, without the need to exchange the solvent . The hydrogenation conditions may be appropriately selected depending on the type of hydrogenation catalyst, and the hydrogenation catalyst is preferably used in an amount of 0.01-50 parts by weight based on 100 parts by weight of the ring-opened polymer. Further, in order to appropriately control the reaction rate and the hydrogenation efficiency, the reaction is preferably conducted at -10~250^°C under 0.01-10 MPa for 0.1-50 hours.

In the present invention, the term "norbornene monomer" indicates a monomer containing at least one norbornene (bicyclo [2, 2, 1] hept-2-ene) ) unit, as represented by Formula 3 below:

Formula 3

The norbornene monomer represented by Formula 2 may be obtained by subjecting cyclopentadiene (CPD) , dicyclopentadiene (DCPD) , or a mixture thereof, which is substituted or unsubstituted with an alkyl group, and alkylacrylate, having an adamantyl group, to a Diels-Alder reaction. Specifically, CPD, DCPD or a mixture thereof, which is substituted or unsubstituted with an alkyl group, and alkylacrylate, having an adamantyl group, are reacted at a molar ratio of 1:0.5-10, and preferably 1:0.5-4.

The reaction temperature therefor is 180-220 ^°C, and the reaction pressure is atmospheric pressure or more.

When the monomer of Formula 2 is synthesized, a polymerization inhibitor may be added to adjust n in Formula 2 to a desired numeral. The polymerization inhibitor is selected from the group consisting of aniline, cyclohexane, phenol, 4-epoxyphenol, nitrobenzene, hydroquinone, benzoquinone, copper dichloride, and 2,2- di (4-tert-octylphenyl) -1-picrylhydrazyl, and preferably, hydroquinone or benzoquinone is used, but the present invention is not limited thereto.

The polymerization inhibitor is added such that the molar ratio of the CPD, DCPD or mixture thereof, which is substituted or unsubstituted with an alkyl group, to the polymerization inhibitor is 1:0.001-0.05, and preferably 1:0.002-0.04.

The monomer thus obtained is represented by Formula 2. In Formula 2, at least one of Ri to R₃, in particular, Ri, is not a hydrogen atom. This monomeric structure functions to increase the amorphous properties of a polymer having it as a repeating unit to thus increase light transmittance.

As the organic solvent, alcohol may be used alone or in a mixture with water or another organic solvent such as tetrahydrofuran, other than the alcohol. The alcohol is exemplified by methanol, ethanol, isopropanol, butanol, etc. Although the temperature for the polymerization varies depending on the type of solvent, it is maintained at 20~100^°C, and the polymerization is conducted for 1-24 hours, thus preparing the norbornene polymer. The norbornene polymer Ls dissolved in the solvent, and is manufactured into a film or a sheet through a solvent casting process. The manufactured film has a thickness of 50~500 μm, a high refractive index of 1.5 or more, and light transmittance of 0.9 or more according to Equation 1 below: Equation 1

=τ

Io

^o intensity of light incident perpendicular to a substrate

/ — a intensity of light absorbed by a substrate

/ _⁼⁼ intensity of light reflected from a substrate

[Mode for Invention]

A better understanding of the present invention may be obtained through the following examples, which are set forth to illustrate, but are not to be construed as the limit of the present invention.

Synthesis of Norbornene Monomer (Synthesis Examples 1~4 and Comparative Synthesis Examples 1~2) <Synthesis Example 1> Synthesis of 2-Methyl-2- Adamantyl-5-Norbornene-2-Methyl-2-Carboxylate

In a 0.25 I autoclave, DCPD (dicyclopentadiene, Aldrich, 10.2 ml, 0.0757 mol) , 2-methyl-2- adamantylmethacrylate (42.6 g, 0.18 mol), and hydroquinone

(0.83 g, 0.1 mol) were placed, and were then reacted at

180^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 110^°C (yield: 85%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product was 48.5:51.5.

¹H-NMR (500MHz, CDCl₃), endo: δ β.20 (dd, IH), 6.18 (dd, IH); exo: 66.12 (m, 2H)

<Synthesis Example 2> Synthesis of 2-Ethyl-2- Adamantyl-5-Norbornene-2-Methyl-2-Carboxylate

In a 0.25 i autoclave, DCPD (dicyclopentadiene, Aldrich, 10.2 ml, 0.0757 mol), 2-ethyl-2- adamantylmethacrylate (44.3 g, 0.18 mol), and hydroquinone

(0.83 g, 0.1 mol) were placed, and were then reacted at

200^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 120^°C (yield: 87%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product was 45.5:54.5.

¹H-NMR (500MHz, CDCl₃), endo: 56.22 (dd, IH), 6.19 (dd, IH); exo: 56.18 (m, 2H)

<Synthesis Example 3> Synthesis of 2-Methyl-2- Adamantyl-5-Norbornene-2-Ethyl-2-Carboxylate

In a 0.25 i autoclave, DCPD (dicyclopentadiene,

Aldrich, 10.2 ml, 0.0757 mol) , 2-methyl-2- adamantylethacrylate (44.3 g, 0.18 mol), and hydroquinone

(0.83 g, 0.1 mol) were placed, and were then reacted at

210^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 117 ^°C (yield: 79%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product was 40.2:59.8.

¹H-NMR (500MHz, CDCl₃), endo: 56.20 (dd, IH), 6.18 (dd, IH); exo: 56.14 (m, 2H)

<Synthesis Example 4> Synthesis of l-Adamantyl-5- Norbornene-2-Methyl-2-Carboxylate

In a 0.25 i autoclave, DCPD (dicyclopentadiene,

Aldrich, 10.2 ml, 0.0757 mol), 1-adamantylmethacrylate (40.0 g, 0.18 mol), and hydroquinone (0.83 g, 0.1 mol) were placed and then reacted at 200^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 100^°C (yield: 85%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product is 40.9:59.1.

¹H-NMR (500MHz, CDCl₃), endo: 66.18 (dd, IH), 6.04 (dd, IH); exo: 56.12 (dd, IH), 6.04 (dd, IH)

<Cαmparat±ve Synthesis Example 1> Synthesis of Norbornene-2-Carboxylic Acid Methyl Ester

In a 0.5 I autoclave, DCPD (dicyclopentadiene, Aldrich, 67 ml, 0.5 mol) , methylacrylate (Aldrich, 94.6 ml, 1.05 mol), and hydroquinone (2.3 g, 0.02 mol) were placed, and were then reacted at 200^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 50^°C

(yield: 69%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product was 52.8:47.2. 1H-NMR (500MHz, CDCl₃), endo: 66.17 (dd, IH), 5.91

(dd, IH); exo: δ 6.09 (m, 2H)

<Comparative Synthesis Example 2> Synthesis of Norbornene-2 , 3-Dicarboxylic Acid Anhydride In a 0.5 I autoclave, DCPD (dicyclopentadiene, Aldrich, 67 ml, 0.5 mol), maleic anhydride (Aldrich, 103.0 g, 1.05 mol) , and hydroquinone (2.3 g, 0.02 mol) were placed, and were then reacted at 200^°C for 12 hours, after which the reaction product was cooled, transferred into a distiller, and subjected to vacuum distillation at 1 torr using a vacuum pump, thus obtaining a desired product at 85^°C (yield: 61%) . The molar ratio (mol%) of the exo isomer to the endo isomer of the product was 54.5:45.5.

¹H-NMR (500MHz, CDCl₃), endo: δ l.66 (d, IH), 1.45 (d, IH); exo: δ l.79 (d, IH), 1.58 (d, IH)

Synthesis of Norbornene Polymer (Examples 1~6 and Comparative Examples 1~2)

<Example 1> 2-Methyl-2-Adamantyl-5-Norbornene-2- Methyl-2-Carboxylate Homopolymer a. 1.00 g (3.33 mmol) of the 2-methyl-2-adamantyl-5- norbornene-2-methyl-2-carboxylate monomer obtained in Synthesis Example 1 was dissolved in dichloroethane with stirring at room temperature, added with 2.74 mg (3.33 μmol) of a benzylidene-bis (tricyclophosphine) dichlororuthenium catalyst in 0.5 ml of dichloroethane, and then stirred. After 2-3 hours, a methanol solution was added in droplets to stop the polymerization, after which the reaction solution was poured on 200-300 ml of methanol to thus precipitate, thereby obtaining a white polymer resin product. The product was dissolved again in 10-30 ml of dichloroethane, added in droplets to a large amount of methanol to thus precipitate, purified, and dried, thus obtaining a ring-opened polymer at a yield of 95% . The polymer thus obtained had a weight average molecular weight of 75,000 and a degree of polymerization of 1.12, according to GPC analysis. b. 10.0 g of the ring-opened polymer obtained in a was dissolved in 100 ml of dichloroethane and the total amount thereof was placed in an autoclave equipped with a stirrer, after which the inner atmosphere of the autoclave was changed to nitrogen. Subsequently, the autoclave was sealed, after which hydrogen gas was supplied at 5 MPa and then stirring was conducted at 120^°C for 24 hours. After the completion of the reaction, the reaction solution was re-precipitated in 1000 ml of methanol, thus obtaining a saturated ring-opened polymer. The yield was 88%.

<Exaraple 2> 2-Ethyl-2-Adamantyl-5-Norbornene-2- Methyl-2-Carboxylate Hαmopolymer a. Polymerization was conducted in the same manner as in Example 1, with the exception that 1.00 g (3.17 mmol) of the 2-ethyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate obtained in Synthesis Example 2 was used instead of the 2- methyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate, and 2.60 mg (3.17 μmol) of a benzylidene- bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 86%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 69,000 and a degree of polymerization of 1.92. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 82%.

<Example 3> 2-Methyl-2-Adamantyl-5-Norbornene-2- Ethyl-2-Carboxylate Homopolymer a. Polymerization was conducted in the same manner as in Example 1, with the exception that 1.00 g (3.17 mmol) of the 2-methyl-2-adamantyl-5-norbornene-2-ethyl-2-carboxylate obtained in Synthesis Example 3 was used instead of the 2- methyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate, and

2.60 mg (3.17 μmol) of a benzylidene- bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 89%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 76,000 and a degree of polymerization of 1.75. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 86%.

<Example 4> l-Adamantyl-5-Norbornene-2-Methyl-2- Carboxylate Homopolymer a. Polymerization was conducted in the same manner as in Example 1, with the exception that 1.00 g (3.49 mmol) of the l-adamantyl-5-norboinene-2-methyl-2-carboxylate obtained in Synthesis Example 4 was used instead of the 2- methyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate, and 2.87 mg (3.49 μmol) of a benzylidene- bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 91%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 63,000 and a degree of polymerization of 1.56. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 85%.

<Example 5> Copolymer of 2-Methyl-2-Adamantyl-5- Norbornene-2-Methyl-2-Carboxylate and l-Adamantyl-5- Norbornene-2-Methyl-2-Carboxylate a. Polymerization was conducted in the same manner as in Example 1, with the exception that 0.50 g (1.67 mmol) of the 2-methyl-2-adamantyl-5-norbornene-2-methyl-2- carboxylate and 0.48 g (1.67 mmol) of the l-adamantyl-5- norbornene-2-methyl-2-carboxylate obtained in Synthesis

Example 4 were used, and 2.75 mg (3.34 μmol) of a benzylidene-bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 82%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 67,000 and a degree of polymerization of 2.21. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 74%. <Example 6> Copolymer of 2-Methyl-2-Adamantyl-5- Norbornene-2-Methyl-2-Carboxylate and Norbornene-2 , 3- Dicarboxylic Acid Anhydride a. Polymerization was conducted in the same manner as in Example 1, with the exception that 0.51 g (1.70 mmol) of the 2-methyl-2-adamantyl-5-norbornene-2-methyl-2- carboxylate and 0.28 g (1.70 mmol) of the norbornene-2, 3- dicarboxylic acid anhydride obtained in Comparative Synthesis Example 2 were used, and 2.80 mg (3.40 μmol) of a benzylidene-bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 59%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 37,000 and a degree of polymerization of 2.11. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 51%.

<Comparative Example 1> Norbornene-2-Carboxylic Acid Methyl Ester Homopolymer a. Polymerization was conducted in the same manner as in Example 1, with the exception that 1.00 g (6.57 mmol) of the norbornene-2-carboxylic acid methyl ester obtained in Comparative Synthesis Example 1 was used instead of the 2- methyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate, and 5.40 mg (6.57 μmol) of a benzylidene- bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 80%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 25,000 and a degree of polymerization of 2.11. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 74%.

<Comparative Example 2> Norbornene-2 , 3-Dicarboxylic Acid Anhydride Homopolymer a. Polymerization was conducted in the same manner as in Example 1, with the exception that 1.00 g (6.09 mmol) of the norbornene-2, 3-dicarboxylic acid anhydride obtained in Comparative Synthesis Example 2 was used instead of the 2- methyl-2-adamantyl-5-norbornene-2-methyl-2-carboxylate, and 5.01 mg (6.09 μmol) of a benzylidene- bis (tricyclophosphine) dichlororuthenium catalyst was used. The yield was 82%, and, according to GPC analysis, the resultant polymer had a weight average molecular weight of 19,000 and a degree of polymerization of 2.35. b. A saturated ring-opened polymer was obtained in the same manner as in Example 1. The yield was 72%.

Manufacture of Film

Using the polymers obtained in Examples 1-6 and Comparative Examples 1~2, respective films were manufactured. Specifically, each of the polymers obtained in Examples 1-6 and Comparative Examples 1-2 was mixed with an organic solvent according to a composition shown in Table 1 below, to prepare a coating solution. Subsequently, the coating solution was cast on a glass substrate using an applicator (Yoshimitsu YBA-4) , dried at room temperature for 1 hour, and then further dried at 100 ^°C for 18 hours in a nitrogen atmosphere. Subsequently, the dried glass substrate was allowed to stand at -10 ^°C for 10 sec, after which the film was removed from the glass substrate using a knife, thereby obtaining the transparent films of Examples 7~18 and Comparative Examples 3~β, having uniform thicknesses, in which the thickness deviation was less than 5%, as shown in Table 1.

TABLE 1

(1) Glass Transition Temperature

The glass transition temperature of each of the polymers of Examples 1~6 and Comparative Examples 1~2 was measured using TGA (Thermogravimetric Analysis) and DSC

(Differential Scanning Calorimetry) . The results are shown in Table 2 below.

TABLE 2

(2) Light Transmittance

Each of the films of Examples 7-18 and Comparative Examples 3-6 was measured for the intensity of light incident perpendicular to a substrate, the intensity of light absorbed by a substrate, and the intensity of light reflected from a substrate at 400-800 nm using a hazemeter (Nippon Denshoku 300A) . The measured values were substituted into Equation 1 below, thus determining light transmittance. The results are shown in Table 3 below. Equation 1

J .

⁰ intensity of light incident perpendicular to a substrate

a intensity of light absorbed by a substrate

r intensity of light reflected from a substrate

(3) Refractive Index

Each of the films of Examples 7~18 and Comparative Examples 3~β was measured for refractive index using an Abbe refractometer and a sodium light source at 25⁰C. The results are shown in Table 3 below.

TABLE 3

As is apparent from the results of the evaluation, the norbornene polymer according to the present invention had a glass transition temperature of 200^°C or higher, and thus superior thermal stability, thus making it suitable for use as electronic material. Further, the film formed using the norbornene polymer, despite having an adamantyl group as a bulky substituent, had higher light transmittance and refractive index than the film manufactured using the polymer having no bulky substituent. Therefore, an optical material prepared using the norbornene polymer of the present invention can exhibit superior optical properties and heat resistance, and thus can be applied not only as material for heat-resistant optical parts, for example, plastic lenses, pick-up lenses for optical disks, and lenses for duplicators, but also as material for protective films of semiconductors, circuit protectors, and electrical insulation films.

[industrial Applicability] As described hereinbefore, the present invention provides a norbornene homopolymer or copolymer obtained from a norbornene monomer having a bulky substituent and a method of preparing the same. Thereby, the norbornene homopolymer or copolymer can exhibit superior heat resistance and optical properties and is thus suitable for use as material for heat- resistant optical parts and electronic parts.

Claims

[CLAIMS]

[Claim l]

A norbornene homopolymer or copolymer, comprising a repeating unit represented by Formula 1 below: Formula 1

wherein Ri, R₂ and R₃, which are same as or different from each other, are a hydrogen atom, a C_H0 linear or branched alkyl group, or a C₅~i₂ cyclic alkyl group, at least one of Ri, R₂ and R₃ not being a hydrogen atom, and R₄ is

selected from among

, and

in which R₅ is a hydrogen atom, a Ci_~io linear or branched alkyl group, or a C₅-_I2 cyclic alkyl group; X is -CH=CH- or - CH₂CH₂-; and n is an integer of 0 or more.

[Claim 2]

The norbornene homopolymer or copolymer according to claim 1, which has a weight average molecular weight ranging from 15,000 to 600,000.

[Claim 3]

A method of preparing a norbornene homopolymer or copolymer, comprising polymerizing a norbornene monomer represented by Formula 2, below, in presence of a metathesis polymerization catalyst: Formula 2

wherein R₁, R₂ and R₃, which are same as or different from each other, are a hydrogen atom, a Ci~io linear or branched alkyl group, or a Cs~i₂ cyclic alkyl group, at least one of Ri, R₂ and R₃ not being a hydrogen atom, and R₄ is

selected from among

, and

in which R₅ is a hydrogen atom, a C₁-_Io linear or branched alkyl group, or a Cs-^ cyclic alkyl group; and n is an integer of 0 or more.

[Claim 4]

The method according to claim 3, wherein the metathesis polymerization catalyst is a ruthenium-based catalyst.

[Claim 5]

The method according to claim 3 or 4, further comprising subjecting a carbon-carbon double bond of the norbornene homopolymer or copolymer to hydrogenation in presence of a hydrogenation catalyst.

[Claim 6]

An optical material, comprising the norbornene homopolymer or copolymer of claim 1 or 2.

[Claim 7]

The optical material according to claim 6, which has a refractive index of 1.5 or more.

[Claim 8]

The optical material according to claim 6, which has a light transmittance of 0.9 or more, according to Equation 1 below: Equation 1

intensity of light incident perpendicular to a substrate j a intensity of light absorbed by a substrate l_r= intensity of light reflected from a substrate.