KR20240013551A - Polycarbonate resin composition - Google Patents

Abstract

The present invention relates to a polycarbonate resin composition with excellent optical properties.

Description

Polycarbonate resin composition {Polycarbonate resin composition}

The present invention relates to a polycarbonate resin composition with excellent optical properties.

Recently, as liquid crystal display devices have become thinner and larger, the thickness of the components used in them is also becoming thinner. The liquid crystal display device is equipped with a backlight, which is a luminous part that emits light from behind the LCD, and a light guide plate or diffusion plate is used to diffuse or transmit light depending on the type and location of the light source. The thickness of the light guide plate is also becoming thinner according to recent trends. The general level of the light guide plate actually used is about 0.5 mm thick, but the thinnest is about 0.3 mm, and the thickness is trending to become even thinner in the future.

Due to the trend toward thinning, the use of edge-type backlight units with LEDs mounted on the corners of the backlight is increasing, replacing the cold cathode fluorescent lamps (CCFLs) that were mainly used previously. The edge-type backlight unit is a surface light source in which light originating from a light source mounted at the corner is transmitted through the light guide plate, and part of the light that passes through the plate is scattered by the light scattering layer applied to the surface of the plate, causing the entire surface to emit light evenly. This illuminates the liquid crystal display device. This light scattering layer is formed by transferring or printing a dot pattern on the surface of the light guide plate, and recently, a fine prism structure has been transferred to increase light efficiency.

Because the light guide plate requires high light transmittance, PMMA, an acrylic resin, was commonly used as a material for the light guide plate. Although acrylic resin has high light transmittance, it is not suitable for application to thin light guide plates due to its lack of mechanical strength, and has the disadvantage of being vulnerable to heat generated from electronic devices due to its lack of heat resistance.

Polycarbonate is attracting attention as a replacement for such acrylic resin. Polycarbonate has superior mechanical strength compared to acrylic resin, so it can be used as a material for thin light guide plates. It also has excellent heat resistance and flame retardancy, so it is gradually replacing acrylic resin in LED backlight units and lighting fixtures with large heat generation. However, since polycarbonate has a lower total light transmittance than acrylic resin, it is required to have a light transmittance comparable to that of acrylic resin while maintaining the advantages of polycarbonate.

In this regard, Japanese Patent Publication No. 2008-045131 mixes PMMA with a viscosity average molecular weight (Mv) of 20,000 to 60,000 among acrylic resins to polycarbonate with Mv of 15,000 to 40,000 in the range of 0.1 to 0.3 phr to achieve excellent photoconductivity. There is a suggestion. However, physical properties such as heat resistance still need to be improved.

Accordingly, while researching materials that can be used as a material for a light guide plate, the present inventors discovered a resin composition containing polycarbonate, polyoxytetramethylene-polyoxypropylene glycol random copolymer, and polypropylene glycol, as will be described below, The present invention was completed by confirming that it can be used as a material for a light guide plate due to its excellent transmittance and color stability.

The present invention is to provide a polycarbonate resin composition with excellent transmittance, excellent color uniformity, and excellent processability.

In order to solve the above problems, the present invention provides a polycarbonate comprising a repeating unit represented by the following formula (1); Polyoxytetramethylene-polyoxypropylene glycol random copolymer represented by the following formula (2); and polypropylene glycol represented by the following formula (3), wherein the weight ratio of the polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol is 1:9 to 9:1. :

[Formula 1]

In Formula 1,

R ₁ to R ₄ are each independently hydrogen, C _1-10 alkyl, C _1-10 alkoxy, or halogen,

Z is C _1-10 alkylene unsubstituted or substituted with phenyl, C _3-15 cycloalkylene unsubstituted or substituted with C _1-10 alkyl, O, S, SO, SO ₂ , or CO,

[Formula 2]

In Formula 2,

n and m are each independently integers of 1 or more,

n+m is 20 or more and less than 100,

[Formula 3]

In Formula 3 above,

p is an integer from 1 to 100.

Additionally, the present invention provides an optical molded article comprising the polycarbonate resin composition.

Since the present invention can be subject to various changes and can take various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Hereinafter, a polycarbonate resin composition and a molded article thereof according to specific embodiments of the invention will be described in more detail.

Prior to this, the terminology used in this specification is only for referring to specific implementation examples and is not intended to limit the invention. And, as used herein, singular forms include plural forms unless phrases clearly indicate the contrary.

polycarbonate

The term 'polycarbonate' used in the present invention refers to a polymer produced by reacting a diphenol-based compound, phosgene, carbonate ester, or a combination thereof. Polycarbonate has excellent heat resistance, impact resistance, mechanical strength, transparency, etc., and is widely used in the manufacture of compact discs, transparent sheets, packaging materials, automobile bumpers, and UV-blocking films. In particular, in the present invention, it is used as a material for the light guide layer. use.

Polycarbonate according to the present invention refers to a repeating unit formed by reacting an aromatic diol and a carbonate precursor.

The polycarbonate includes a repeating unit represented by the following formula (1):

[Formula 1]

In Formula 1,

R ₁ to R ₄ are each independently hydrogen, C _1-10 alkyl, C _1-10 alkoxy, or halogen,

Z is C _1-10 alkylene unsubstituted or substituted with phenyl, C _3-15 cycloalkylene unsubstituted or substituted with C _1-10 alkyl, O, S, SO, SO ₂ , or CO.

Preferably, R ₁ to R ₄ are each independently hydrogen, C _1-4 alkyl, or halogen. More preferably, R ₁ to R ₄ are each independently hydrogen, methyl, chloro, or bromo.

Also preferably, Z is straight or branched C _1-10 alkylene that is unsubstituted or substituted with phenyl, more preferably methylene, ethane-1,1-diyl, propane-2,2-diyl, butane-2,2-diyl, 1-phenylethane-1,1-diyl, or diphenylmethylene. Also preferably, Z is cyclohexane-1,1-diyl, O, S, SO, SO ₂ , or CO.

Preferably, the compound represented by Formula 1 is bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl) Sulfoxide, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 2,2-bis(4-hydroxy-3 ,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2 , 2-bis (4-hydroxy-3-chlorophenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane (bisphenol C), 2,2-bis (4-hydroxy-3 , 5-dimethylphenyl) propane and 1,1-bis (4-hydroxyphenyl) -1-phenylethane.

The meaning of ‘derived from an aromatic diol compound’ means that the hydroxyl group of the aromatic diol compound and the carbonate precursor react to form a repeating unit represented by Formula 1 above.

For example, when bisphenol A, an aromatic diol compound, and triphosgene, a carbonate precursor, are polymerized, the repeating unit represented by Formula 1 is represented by Formula 1-1 below.

[Formula 1-1]

The carbonate precursors include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditoryl carbonate, bis(chlorophenyl) carbonate, di-m-cresyl carbonate, dinaphthyl carbonate, One or more types selected from the group consisting of bis(diphenyl) carbonate, phosgene, triphosgene, diphosgene, bromophosgene, and bishaloformate may be used. Preferably, triphosgene or phosgene can be used.

Presumably, the polycarbonate has a weight average molecular weight of 15,000 g/mol to 50,000 g/mol. Within the above range, formability and workability are excellent when manufacturing thin film products. In this specification, examples of methods for measuring weight average molecular weight are not greatly limited, but for example, the weight average molecular weight converted to polycarbonate (standard material, e.g., bisphenol A type linear PC) measured by GPC method can be used. . In the process of measuring the weight average molecular weight of polycarbonate equivalent measured by the GPC method, detectors and analysis devices such as commonly known analysis devices (GPC measurement equipment, e.g. Agilent 1200 series) and differential refractive detectors (Refractive Index Detector) are used. Columns can be used, and commonly applied temperature conditions, solvents, and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 25°C, tetrahydrofuran solvent, and a flow rate of 1 mL/min. More preferably, the weight average molecular weight of the polycarbonate is at least 20,000 g/mol, at least 25,000 g/mol, or at least 30,000 g/mol, and at most 70,000 g/mol, or at most 60,000 g/mol, or at least 50,000 g/mol. It may be less than mol.

Polyoxytetramethylene-polyoxypropylene glycol random copolymer

Meanwhile, the polycarbonate has relatively excellent mechanical properties, electrical properties, and weather resistance compared to other types of resin, so it can be used as a light guide plate. However, since the light transmittance, which is an important consideration in the light guide plate, is rather low, there is a need to improve it. Accordingly, in the present invention, polyoxytetramethylene-polyoxypropylene glycol random copolymer represented by the following formula (2) is used together with the polycarbonate.

[Formula 2]

In Formula 2,

n and m are each independently integers of 1 or more,

n+m is 20 or more and less than 100.

The term 'polyoxytetramethylene-polyoxypropylene glycol random copolymer' used in the present invention refers to a polymer produced by randomly copolymerizing tetrahydrofuran and propylene oxide. From this perspective, the repeating units between square brackets in Formula 1 should be understood as being randomly arranged.

Conventionally, there have been attempts to improve light transmittance in a light guide plate by adding polyoxyalkylene glycol. However, in the case of polyoxypropylene glycol, although compatibility with polycarbonate is high, heat resistance is low, so a problem occurs in which light transmittance is lowered due to high temperature during the production of the light guide plate. In addition, in the case of polyoxytetramethylene glycol, although heat resistance is high, it is difficult to improve light transmittance because compatibility with polycarbonate is poor.

However, the polyoxytetramethylene-polyoxypropylene glycol random copolymer containing all of the repeating units as in the present invention compensates for the disadvantages of each polyoxyalkylene glycol, improving both heat resistance and light transmittance. You can do it.

The polyoxytetramethylene-polyoxypropylene glycol random copolymer preferably has a weight average molecular weight of 1,000 g/mol to 4,000 g/mol. Within the above range, the physical properties of the light guide plate can be effectively improved.

In addition, the polyoxytetramethylene-polyoxypropylene glycol random copolymer is included in an amount of 200 to 10,000 ppm based on the total weight of the polycarbonate resin composition, preferably 250 ppm or more, 300 ppm or more, or 350 ppm or more, and 9000 ppm or more. ppm or less, 8000 ppm or less, 7000 ppm, or 5000 ppm or less. Below 200 ppm, the degree of improvement in light transmittance is minimal, and above 10,000 ppm, the properties of polycarbonate may deteriorate.

polypropylene glycol

In addition, in order to further improve the optical properties of the polycarbonate, the polycarbonate, polyoxytetramethylene-polyoxypropylene glycol random copolymer, and polypropylene glycol are used together.

The term ‘polypropylene glycol’ used in the present invention is a polymer represented by the following formula (3) and can be produced by a homopolymerization reaction of propylene glycol:

[Formula 3]

In Formula 3 above,

p is an integer from 1 to 100.

The weight average molecular weight of the polypropylene glycol is preferably 1,000 g/mol to 4,000 g/mol. Within the above range, the physical properties of the light guide plate can be effectively improved.

In addition, the polypropylene glycol is contained in an amount of 200 to 10,000 ppm based on the total weight of the polycarbonate resin composition, preferably 250 ppm or more, 300 ppm or more, or 350 ppm or more, and 9000 ppm or less, 8000 ppm or less, 7000 ppm or more. ppm, or contained below 5000 ppm. Below 200 ppm, the degree of improvement in light transmittance is minimal, and above 10,000 ppm, the properties of polycarbonate may deteriorate.

polycarbonate resin composition

The polycarbonate resin composition according to the present invention uses a mixture of the polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol, specifically, polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene. The weight ratio of glycol is 1:9 to 9:1.

The inventors of the present invention mixed polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol, compared to the comparative example in which polyol-based additives polyoxypropylene glycol and polyoxytetramethylene glycol or polypropylene glycol were used alone. When used, it was confirmed that optical properties were improved due to their synergistic effect, and in particular, long light transmittance was improved, thereby completing the present invention.

Preferably, the weight ratio of the polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol is 1.5:8.5 to 8.5:1.5, 2:8 to 8:2, 2.5:7.5 to 7.5:2.5, or 3. :7 to 7:3. When included in the above weight ratio, the effect of improving optical properties can be further improved without deteriorating the physical properties of the polycarbonate resin.

Additionally, if necessary, the polycarbonate resin composition may contain one type from the group consisting of antioxidants, heat stabilizers, plasticizers, antistatic agents, nucleating agents, flame retardants, lubricants, impact modifiers, fluorescent whiteners, and ultraviolet absorbers commonly used in the art. Additional additives selected from the above may be included.

The antioxidant prevents oxidation of the polycarbonate resin composition and molded articles formed therefrom and maintains their physical properties. Such antioxidants may include phosphite-based antioxidants, hindered phenol-based antioxidants, phosphorus-based antioxidants, thio-based antioxidants, or mixtures thereof.

Examples of the phosphite antioxidant include PEP-36 (Bis(2,6-di-ter-butyl-4-methylphenyl)pentaerythritol-diphosphite), and DP9228 (bis(2,4-dicumylphenyl)pentaerythritol diphosphate). Any one or more selected from the group consisting of may be mentioned. In addition, examples of the hindered phenolic antioxidant include IR1010 ([3-[3-(4-hydroxy-3,5-ditert-butyl-phenyl)propanoyloxy]-2,2-bis[3-(4- hydroxy-3,5-ditert-butyl-phenyl)propanoyloxymethyl]propyl] 3-(4-hydroxy-3,5-ditert-butyl-phenyl)propanoate).

The antioxidant may be included in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of polycarbonate. Within this range, deterioration of physical properties due to oxidation can be effectively suppressed.

The polycarbonate resin composition can be prepared by mixing polycarbonate, polyoxytetramethylene-polyoxypropylene glycol random copolymer, polypropylene glycol, and additives as needed, and can be melted to produce optical molded products as will be described below. It is preferable to knead and produce pellets.

The melt kneading may be carried out by a method commonly used in the art, such as a ribbon blender, Henschel mixer, Banbury mixer, drum tumbler, single screw extruder, twin screw extruder, conider, multi-screw extruder, etc. You can. The temperature of the melt kneading can be adjusted appropriately as needed, and is preferably adjusted to a temperature of 200°C to 300°C.

optical molded products

Additionally, the present invention provides an optical molded article containing the polycarbonate resin composition. Preferably, the optical molded article is a light guide plate.

The term 'light guide plate' used in the present invention refers to a component that performs the brightness and uniform lighting function of the backlight unit of the liquid crystal display device. Since light passes through the light guide plate, transparency, or light transmittance, must be excellent. In addition, since high temperatures are required for forming and operating the light guide plate, high heat resistance is required.

Accordingly, the polycarbonate resin composition according to the present invention can be usefully used as a light guide plate because it has excellent light transmittance and heat resistance required for a light guide plate.

The light guide plate may be manufactured using a method commonly used in the art. For example, injection molding, injection compression molding, extrusion molding, vacuum molding, blow molding, press molding, pressure molding, foam molding, heat bending molding, compression molding, The light guide plate can be manufactured by applying molding methods such as calendar molding and rotation molding.

The thickness of the light guide plate can be appropriately adjusted depending on the purpose of use, and the shape of the light guide plate may also have a flat or curved shape depending on the purpose of use.

The polycarbonate resin composition according to the present invention exhibits excellent optical properties and can be usefully used as a material for a light guide plate.

Below, preferred embodiments are presented to aid understanding of the invention. However, the following examples are provided only to make the present invention easier to understand, and the content of the present invention is not limited thereto.

<Substances used>

The following materials were used in the following examples and comparative examples.

- Polycarbonate resin (PC)

Bisphenol A type linear polycarbonate with a weight average molecular weight of 36,500 g/mol and an MFR (1.2 kg at 300°C) of 120 g/min was used.

- Polyoxytetramethylene-polyoxypropylene glycol random copolymer

Polycerin DCB-2000 from NOF Corporation with a weight average molecular weight of 2,000 g/mol was used.

- Polypropylene glycol

PPG-2000 from KPX, which has a weight average molecular weight of 2,000 g/mol, was used.

- Antioxidants

DP9228: Cas No. 154862-43-8; Bis(2,4-dicumylphenyl) pentaerythritol diphosphite

IR1010: Made by BASF

<Examples and Comparative Examples>

After mixing the contents of each component as shown in Table 1 below, pellets were manufactured at a speed of 80 kg per hour in a twin screw extruder (L/D = 36, Φ = 45, barrel temperature 240°C).

Prescription (ppm) division DCB 2000 PPG 2000 DP9228 IR1010 Example 1 2450 1050 1500 500 Example 2 1750 1750 1500 500 Example 3 1050 2450 1500 500 Example 4 2800 700 1500 500 Example 5 700 2800 1500 500 Example 6 350 3150 1500 500 Example 7 3150 350 1500 500 Comparative Example 1 0 0 0 0 Comparative Example 2 0 0 1500 500 Comparative Example 3 3500 0 1500 500 Comparative Example 4 0 3500 1500 500 Comparative Example 5 175 3325 1500 500 Comparative Example 6 3325 175 1500 500

<Experimental example>

The pellets prepared in Examples and Comparative Examples were injection molded into specimens with a width of 150 mm, a length of 80 mm, and a thickness of 4 mm, and the physical properties were measured by the following method.

(1) Transmittance (3T, Tt%) and color tone (3T, YI)

Transmittance was measured in the range of about 350 to 1050 nm using UltraScan PRO (manufactured by HunterLab) according to ASTM D1003.

(2) Long-light transmittance (150T, Tt%) and long-light color tint (150T, YI)

Using Hitachi's Spectrophotometer U-4100, light was irradiated in a direction perpendicular to the thickness direction of the specimen to measure the 380 to 780 nm long-light transmittance and long-light color tone of the specimen.

The measurement results are shown in Table 2 below.

Transmittance
(3T, Tt%) Y.I.
(3T) long light transmittance
(150T, Tt%) Jang Gwang YI
(150T) Example 1 91.5 0.7 76.7 7.7 Example 2 91.6 0.7 78.1 6.5 Example 3 91.5 0.7 77.2 7.9 Example 4 91.5 0.7 76.6 7.6 Example 5 91.3 0.7 76.1 8.1 Example 6 91.4 0.7 74.1 8.0 Example 7 91.6 0.8 76.0 8.1 Comparative Example 1 91.4 0.9 72.9 12.1 Comparative Example 2 91.5 0.8 75.9 80.3 Comparative Example 3 91.5 0.8 75.7 8.7 Comparative Example 4 91.4 0.9 68.6 10.3 Comparative Example 5 91.3 0.9 73.5 9.0 Comparative Example 6 91.6 0.7 75.8 8.5

As shown in Table 2 above, as can be seen in the present invention, the polycarbonate composition according to the present invention is excellent in transmittance, color tone, long light transmittance, and long light color tone, and can achieve a uniform and stable color tone, It was confirmed that excellent optical characteristics can be achieved when applied to a light guide plate.

Claims (12)

Polycarbonate containing a repeating unit represented by the following formula (1);
Polyoxytetramethylene-polyoxypropylene glycol random copolymer represented by the following formula (2); and
Contains polypropylene glycol represented by the following formula (3),
The weight ratio of the polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol is 1:9 to 9:1,
Polycarbonate resin composition:
[Formula 1]

In Formula 1,
R ₁ to R ₄ are each independently hydrogen, C _1-10 alkyl, C _1-10 alkoxy, or halogen,
Z is C _1-10 alkylene unsubstituted or substituted with phenyl, C _3-15 cycloalkylene unsubstituted or substituted with C _1-10 alkyl, O, S, SO, SO ₂ , or CO,
[Formula 2]

In Formula 2,
n and m are each independently integers of 1 or more,
n+m is 20 or more and less than 100,
[Formula 3]

In Formula 3 above,
p is an integer from 1 to 100.
According to paragraph 1,
The repeating unit represented by Formula 1 is bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, and bis(4-hydroxyphenyl)sulfoxide. , bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 2,2-bis(4-hydroxy-3,5 -Dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2 -bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C), 2,2-bis(4-hydroxy-3,5 -Dimethylphenyl)propane and 1,1-bis(4-hydroxyphenyl)-1-phenylethane, characterized in that it is derived from any one or more aromatic diol compounds selected from the group consisting of,
Polycarbonate resin composition.
According to paragraph 1,
The repeating unit represented by Formula 1 is characterized in that it is represented by the following Formula 1-1,
Polycarbonate resin composition.
[Formula 1-1]

According to paragraph 1,
The weight average molecular weight of the polycarbonate is 15,000 g/mol to 50,000 g/mol,
Polycarbonate resin composition.
According to paragraph 1,
The weight ratio of the polyoxytetramethylene-polyoxypropylene glycol random copolymer and polypropylene glycol is 1.5:8.5 to 8.5:1.5,
Polycarbonate resin composition.
According to paragraph 1,
The weight average molecular weight of the polyoxytetramethylene-polyoxypropylene glycol random copolymer is 1,000 g/mol to 4,000 g/mol,
Polycarbonate resin composition.
According to paragraph 1,
The polyoxytetramethylene-polyoxypropylene glycol random copolymer is contained in an amount of 200 to 10,000 ppm based on the total weight of the polycarbonate resin composition.
Polycarbonate resin composition.
According to paragraph 1,
The weight average molecular weight of the polypropylene glycol is 1,000 to 4,000 g/mol,
Polycarbonate resin composition.
According to paragraph 1,
The polypropylene glycol is contained in an amount of 200 to 5000 ppm based on the total weight of the polycarbonate resin composition.
Polycarbonate resin composition.
According to paragraph 1,
The polycarbonate resin composition further contains one or more additives selected from the group consisting of antioxidants, heat stabilizers, plasticizers, antistatic agents, nucleating agents, flame retardants, lubricants, impact modifiers, optical brighteners, and ultraviolet absorbers.
Polycarbonate resin composition.
According to clause 10,
The antioxidant includes a phosphite-based antioxidant, a hindered phenol-based antioxidant, or a mixture thereof.
Polycarbonate resin composition.
An optical molded article comprising the polycarbonate resin composition of any one of claims 1 to 11.