KR20090016172A - A polycarbonate resin having a low coefficient of thermal expansion, a method for preparing the same, and an optical film comprising the same - Google Patents

Abstract

A polycarbonate resin is provided to secure excellent light transmittance and low thermal expansion coefficient and to prepare a plastic substrate or a display optical film with excellent performance. A polycarbonate resin is manufactured by reacting a polycarbonate monomer having an epoxy end and silica particles having an amine group on the surface, and has a linkage unit like the following chemical formula 1 or the chemical formula 2. The average molecular weight of the polycarbonate monomer is 400-50,000. A method for manufacturing the polycarbonate resin comprises a step for mixing 100 parts by weight of polycarbonate monomer having an epoxy end and 1-100.0 parts by weight of silica particles having an amine group on the surface; and a step for hardening the raw material mixture at a room temperature to -250 °C.

Description

Polycarbonate resin having a low coefficient of thermal expansion, a method of manufacturing the same, and an optical film comprising the same {A POLYCARBONATE RESIN HAVING A LOW COEFFICIENT OF THERMAL EXPANSION, A METHOD FOR PREPARING THE SAME, AND AN OPTICAL FILM COMPRISING THE SAME}

The present invention relates to a polycarbonate resin having a low coefficient of thermal expansion and suitable for a film material applied to a substrate for a display, a method of manufacturing the same, and an optical film manufactured using the same.

Plastic substrate material is a key material for the implementation of plastic flat panel displays (replacement of existing FPD glass substrates) or next-generation displays (conformable display / flexible displays, e-paper). .

When comparing the physical properties of plastic substrates for flexible displays with conventional glass substrates, weight, deformability, nonbreakability, design, and roll-to are the key characteristics of flexible displays. Plastic material is excellent in terms of roll processability. However, in order to use the plastic optical film for the substrate, it is required to improve the physical properties in terms of weak chemical resistance, thermal properties, and gas barrier properties of the plastic substrate compared to the glass.

In order to use the optical film as a substrate material for a display, various properties such as thermal stability, chemical resistance, excellent optical properties, surface flatness, and mechanical properties are required in combination.

In general, in order to satisfy such various characteristics, an inorganic barrier layer, an undercoat layer, and an overcoat layer are applied to both surfaces of a transparent optical film that is a base film.

In this base film, bare film is a key substrate material that determines the optical properties such as thermal processing temperature of the substrate material, coefficient of thermal expansion (CTE), optical properties such as transparency or birefringence, and mechanical strength. Polycarbonate (PC), Polyethersulphone (PES), Polyester (Polyethlene Terephthalate (PET), Polyimide (PI), Polyarylate (PAR), Polyethylene Naphthalate (PEN) ) Is the most commonly used polymer. The glass substrate and the conventional polymer plastic substrate are as shown in Table 1 below when the physical properties are compared.

 Properties Glass PC PES PET PEN Manufacturing method Fusion Solvent casting Extrusion Extrution & biaxially drawing Extrution & biaxially drawing Density (g / cm ³ ) 2.77 1.2 2.2 5.3 6.1 Glass transition temperature (℃) 690 215 223 78 121 Heat shrink Almost none <0.01 @ 180 ℃ <0.8 @ 180 ℃ MD 1.0 TD 0.5 @ 150 ℃ MD 0.5 TD 0.1 @ 150 ℃ Thermal expansion coefficient (ppm / ℃) 8 70 60 80 20 Light transmittance (%) 91 90 89 89 88 Refractive index 1.54 1.61 1.65 1.66 1.70

* Source: MacDonald W. A., J. Materials Chem. 14 (4) (2004)

Until recently, technical development of substrate materials has been focused on improving glass transition temperature of bare film materials that determine gas barrier properties and substrate process temperatures of barrier layers.

However, the barrier properties have been reported to have recently been improved to a level that satisfies the requirements of the organic light emitting diode (OLED), and the requirements for heat resistance of the substrate material have been gradually relaxed.

In the case of process temperature, amorphous silicon-TFT process temperature is generally around 350 ° C, but the process temperature of plastic LCD is reported to be reduced to 150 ° C. Recently, Samsung Electronics developed a 5-inch and 7-inch TFT-LCD module based on a plastic substrate using a 130 ℃ process, and expects the process temperature to be lowered below 100 ℃ in the future.

However, even if the gas barrier property is secured and the substrate process temperature is lower than the glass transition temperature of the plastic, the flexible display may not be implemented using all the plastic substrates.

Indeed, current TFT processes have been developed for borosilicate glass with a Coefficient of Thermal Expansion (CTE) of 4 ppm / ° C, but very high CTE for isotropic transparent films (eg 70 ppm for PC). / ° C.). Therefore, in the case of the substrate material having a high CTE, the dimensional stability is secured for the implementation of the TFT-array, which requires the micrometer precision due to the misalignment between pixels due to the temperature change during the process. I can't.

In addition, in a plastic substrate having a multi-layered thin film structure having different physical properties, the thermal expansion rate difference between the interlayer materials (polymer and inorganic material) is large, so that thermal stress occurs at the interface during heating / cooling. .

As a result, crack generation and interfacial peeling occur, which makes it difficult to maintain a gas barrier characteristic of the substrate after the process, thereby seriously reducing durability and reliability of the substrate. The problem caused by low CTE is the biggest obstacle to the application of flexible displays, and it is a technical task to be preempted for the practical use of plastic substrates in the future.

However, polymer materials for substrates with low CTE have not been developed so far enough to meet the demands of set-makers worldwide.

It is an object of the present invention to provide a polycarbonate resin having a low coefficient of thermal expansion and a method for producing the same.

Another object of the present invention is to provide an optical film comprising the polycarbonate resin.

The present invention provides a polycarbonate resin prepared by reacting a polycarbonate unit having an epoxy terminal and a silica particle having an amine group on its surface, and having a linking unit such as the following Chemical Formula 1 or Chemical Formula 2 and a method of manufacturing the same.

[Formula 1]

[Formula 2]

The linking unit of Formula 1 or Formula 2 may be present at the sock end of the polycarbonate unit, and a large number may be present on the surface of the silica particles.

In addition, the present invention provides an optical film comprising the polycarbonate resin.

Hereinafter, the present invention will be described in detail.

Polycarbonate (PC), together with Sumitomo Bakelite's polyether sulfone (PES), is the most widely used material for plastic substrates. PC substrate materials have been recently developed by Teijin, Japan.

In recent years, since the general PC is a substrate material for display, the heat resistance is poor and the process progresses. Therefore, the glass transition temperature is higher than 60 ° C. and the thermal strain at 180 ° C. is higher than 0.05%. And a substrate PC having a small retardation of less than 1 nm. Deijin's PCs have been applied to mobile phones (monochrome STN-LCDs) since 1999, and are currently producing 500,000 to 600,000 units per month.

In the present invention, in order to improve the coefficient of thermal expansion of the polymer without inhibiting the optical properties of the polycarbonate, an inorganic filler can be added, in which case the interfacial adhesion between the inorganic filler and the polymer is one of the very important factors. Therefore, the present invention is to synthesize a polycarbonate or a polycarbonate having a low CTE by using a synthetic filler having a functional group capable of reacting with the polycarbonate precursor.

In the present invention, the polycarbonate unit having an epoxy terminal may use a weight average molecular weight of 400 to 50,000, preferably 1,000 to 30,000, so that the polycarbonate unit having an epoxy end may have a more advantageous effect in securing excellent light transmittance and low CTE. Can be used.

In the polycarbonate resin of the present invention, the terminal of the polycarbonate unit is crosslinked by the silica particles, thereby ensuring a low CTE, and the main chain of the polycarbonate unit is at least one of repeating units represented by the following Chemical Formulas 3 to 5 It is preferable to include one but not necessarily limited thereto.

[Formula 3]

[Formula 4]

[Formula 5]

In addition, in the present invention, the silica particles having an amine group on the surface may be those having an average particle diameter of 5 to 900 nm, preferably those having 10 to 500 nm. The silica particles have a lower CTE than the carbonate resin, and when the polymer is added, the average particle diameter is at least 5 nm or more to obtain the effect of improving the CTE, and in order to secure transparency of the polycarbonate composite, the silica particle is preferably 900 nm or less. Do.

The silica particles may be reacted with 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the polycarbonate unit. When the content of the silica particles is 1 part by weight or more to obtain the effect of improving the CTE, in order to secure the transparency of the polycarbonate composite is preferably 100 parts by weight or less.

The polycarbonate resin of the present invention may be prepared by further adding an amine curing agent for epoxy to the polycarbonate unit and the silica particles to control the degree of crosslinking.

As the amine curing agent, an aliphatic amine or an aromatic amine may be used, and an amine compound including two or more primary amine groups may be used. The amine curing agent is diethylene triamine (DETA), diethylene tetraamine, diethylene tetraamine (Triethylene Tetramine, TETA), methane diamine (MDA), N-aminoethyl pyrazine (N-Aminoethyl piperazine, AEP), m-xylene diamine, Isophorone Diamine (IPDI), bis (4-amino 3-methylcyclohexyl) methane (Bis (4-Amino 3) -Methylcyclohexyl) Methane, Larominc 260), N, N'-Diethylenediamine (N, N'-DEDA), Tetraethylenepentaamine (TEPA), and Hexamethylenediamine M-phenylene diamine or 4,4'-dimethylaniline (diamino diphenyl metone) (4,4'-Dimethylaniline (Diamino) diphenyl methone), DAM or DDM), diamino diphenyl sulfone (DDS), 9-dipe 1 selected from the group consisting of -1,4-phenylenediamine, 9-phenyl-1,4-phenylenediamine, 1,3-phenylenediamine, and diaminoeiphenylmethane. It is possible to use more than one aromatic amine.

The amine curing agent may control the degree of curing of the polycarbonate through the reaction with the epoxy group, it is possible to control the content of the amine curing agent based on the epoxy group of the polycarbonate unit according to the desired degree of curing. In particular, in the equivalent reaction of the amine curing agent and the polycarbonate unit, one amine group per two epoxy groups is a quantitative concentration, and in the equivalent reaction, the molar ratio of epoxy group / amine group [NH ₂ ] is 2/1. Concentration ratios can be used. Therefore, in the present invention, the content of the amine curing agent is preferably 1.0 to 2.5 so that the molar ratio of the epoxy group [epoxy group] / amine group [NH ₂ ] to 0.5 to 3.0 based on the epoxy group of the polycarbonate unit. It is preferable to control the polycarbonate resin to be used in view of securing the degree of curing and excellent low thermal expansion coefficient.

The present invention is to prepare a raw material mixture by mixing 100 parts by weight of a polycarbonate unit having an epoxy terminal, 1 to 100 parts by weight of silica particles having an amine group on the surface; It provides a method for producing a polycarbonate resin comprising the step of curing the raw material mixture. At this time, the curing step may be carried out at room temperature (25 ℃) to 250 ℃.

In addition, the present invention may further include the step of (solvent-casting) coating the raw material mixture on a substrate such as a release film, Teflon film, such as to produce an optical film comprising the polycarbonate resin It can be processed into various other forms using molds, etc.

The raw material mixture may further include a solvent in order to dissolve and mix the polycarbonate unit and the silica particles. The solvent is preferably an organic solvent such as THF, chloroform, dichloromethane, and most organic solvents except aliphatic hydrocarbons and alcohols have excellent solubility, and any solvent capable of mixing the above components may be used. .

At this time, the content of the solvent can be adjusted to an appropriate range according to the coating property, preferably it can be used so that the solid content is 5 to 90% by weight, when the solvent content of the raw material mixture is too high, the viscosity is too low to coat well Some solvent may be removed prior to coating to adjust the viscosity to a degree suitable for coating.

In one example of the present invention, a method for producing a polycarbonate resin by reacting a polycarbonate having an epoxy terminal with a silica particle having an amine group on its surface is as shown in Scheme 1 below.

Scheme 1

As another example of the present invention, a method of preparing a polycarbonate resin by reacting a polycarbonate having an epoxy terminal with silica particles having an amine group on its surface and simultaneously using the silica particles and an amine curing agent to control the degree of crosslinking is as follows. As shown in Scheme 2.

Scheme 2

On the other hand, the present invention provides an optical film containing the polycarbonate resin.

In particular, the optical film produced according to the invention is characterized in that the thermal expansion coefficient is 60 ppm / ℃ or less, preferably 10 to 50 ppm / ℃.

The optical film may be prepared by applying the reaction product of the polycarbonate resin of the present invention in the form of a film, and then drying and curing the same.

At this time, in the production method, the type of the catalyst and the solvent used, the content of each component is in accordance with the contents described above, in the production of the film is dried at a temperature of room temperature (25 ℃) to 100 ℃, It is preferable to perform hardening at the temperature of normal temperature (25 degreeC)-250 degreeC from the uniformity of formation of a film.

However, the manufacturing method described only a preferred example of optical film production, the manufacturing method of the optical film of the present invention is not necessarily limited to the above method.

According to the present invention, a polycarbonate resin prepared by reacting a polycarbonate unit having an epoxy terminal with silica particles having an amine group on its surface may be used to produce an optical film having a significantly reduced thermal expansion rate.

Preferred examples are provided to aid the understanding of the present invention, but the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

Example  1. on the surface An amine group  Having Silica Particles Synthesis

As shown in Scheme 3 below, 100 g of colloidal silica (30 wt% in IPA, 40 nm average particle diameter) was added to 200 ml of isopropyl alcohol (IPA), and aminopropyltriethoxy silane ((aminopropyl) was added thereto. 6 g of triethoxy silane (APTES) and 1.4 g of water were mixed.

After adding hydrochloric acid to the mixture to pH 2.5, the mixed solution was reacted with stirring at a reactor temperature of 60 ° C. for 12 hours.

After the stirring reaction, the water in the reaction solution was first removed using MgSO _4, and then the remaining solvent was removed by a 50 ° C. rotary evaporator.

The solvent, almost free of solvent, was dried in a vacuum oven at 50 ° C. for 30 minutes to prepare silica particles having amine groups on the surface.

Scheme 3

Example  2. An amine group Modified  Polycarbonate Film Preparation Using Silica

15 g of glycidyl end-capped poly (bisphenol A-co-epichlorohydrin, M _n = 1700), as a polycarbonate unit having an epoxy end, 5 g of the silica particles prepared in Example 1 and 10 g of diaminodiphenylmethane were mixed at room temperature for 10 minutes, and the solvent was added to the mixed solution at room temperature under vacuum (in 27 in. Hg) for 30 minutes. After some removal, it processed into the film form using the film processing machine.

The film was dried at room temperature for 3 hours and further dried in a vacuum oven. After vacuum drying at room temperature for 15 minutes, it was dried at 50 ° C for 30 minutes and at 70 ° C for 1 hour.

The solvent-free film was cured at 100 ° C. for 1 hour and cured at 150 ° C. for 1 hour to prepare a transparent optical film including a polycarbonate resin.

Through the following evaluation method, it was confirmed that the polycarbonate resin of Example 2 prepared by the above-described manufacturing method has excellent light transmittance and low thermal expansion coefficient.

(1) Coefficient of Thermal Expansion (CTE) Measurement and Results

Instrument: thermal mechanical analyzer (TMA)

-Measurement section and heating rate: normal temperature ~ 200 ℃, 10 ℃ / min

Sample: film form

CTE value: 50 ppm / ° C

(2) Transmittance Measurement and Results

Instrument: UV-VIS spectrometer

Sample: film form

Transmittance: 85% @ 550nm

From the measurement results, the thermal expansion coefficient of the conventional polycarbonate resin is 70 ppm / ℃, while the polycarbonate resin of the present invention has a significantly low thermal expansion coefficient of 50 ppm / ℃, the transmittance is 85% almost the same level It can be seen that.

Polycarbonate resin according to the present invention is a useful technology that can contribute to the industrial development by securing an excellent light transmittance and a low coefficient of thermal expansion, to be able to produce a plastic substrate or a display optical film of higher performance.

Claims (12)

A polycarbonate resin prepared by reacting a polycarbonate unit having an epoxy terminal with silica particles having an amine group on its surface, and having a linking unit represented by the following Chemical Formula 1 or Chemical Formula 2. [Formula 1]

[Formula 2]

The method of claim 1, The polycarbonate unit has a polycarbonate resin having a weight average molecular weight of 400 to 50,000. The method of claim 1, The polycarbonate resin is crosslinked by the silica particles. The method of claim 1, The main chain of the polycarbonate unit is a polycarbonate resin containing at least one of the repeating units represented by the following formula (3). [Formula 3]

[Formula 4]

[Formula 5]

The method of claim 1, The average particle diameter of the silica particles is 5 to 900 nm polycarbonate resin. The method of claim 1, The silica particles are reacted with 1 to 100 parts by weight based on 100 parts by weight of the polycarbonate unit. The method of claim 1, The polycarbonate resin is a polycarbonate resin is prepared by further reacting by further adding an amine curing agent comprising two or more primary amine groups. The method of claim 7, wherein The content of the amine curing agent is a polycarbonate resin prepared by reacting the molar ratio of the epoxy group / amine group is 0.5 to 3.0 based on the epoxy group of the polycarbonate unit. Preparing a raw material mixture by mixing 100 parts by weight of a polycarbonate unit having an epoxy terminal and 1 to 100 parts by weight of silica particles having an amine group on a surface thereof; And Curing the raw material mixture at room temperature to 250 ℃ Method for producing a polycarbonate resin comprising a. The method of claim 9, In the step of preparing the raw material mixture to further react the amine curing agent including two or more primary amine groups in an amount such that the molar ratio of the epoxy group / amine group is 0.5 to 3.0 based on the epoxy group of the polycarbonate unit Method of producing polycarbonate resin An optical film comprising the polycarbonate resin according to any one of claims 1 to 8. The method of claim 11, The optical film has a thermal expansion coefficient of 60 ppm / ℃ or less.