Flame-retardant aromatic polycarbonate resin and molded articles made therefrom

Abstract

The present invention provides a flame-retardant aromatic polycarbonate resin and molded articles made therefrom that exhibit high flame retardancy without the need for flame retardants, as well as good heat resistance and transparency. [Solution] A flame-retardant aromatic polycarbonate resin composed of repeating structural units represented by the following formulas (1) and (2), wherein the molar ratio of the repeating structural units represented by formula (1) is greater than 70% and less than 100%, and the weight-average molecular weight is 10,000 to 100,000. [Formula 1] JPEG2026136460000008.jpg2276 [C2] JPEG2026136460000009.jpg2068

Description

Technical Field

[0001] The present invention relates to a flame-retardant aromatic polycarbonate resin and a molded article made therefrom.

Background Art

[0002] Aromatic polycarbonate resins are used in a wide range of industrial fields as materials for various molded articles by simple and highly productive processing methods such as injection molding. In particular, in applications that require high transparency, such as various lighting covers and protective covers for transmissive displays, they are widely used by taking advantage of the excellent transparency represented by the high light transmittance and extremely low haze of aromatic polycarbonate resins. In addition, in these applications, the flame retardancy during a fire is also attracting attention. Further, the thinning, miniaturization, and weight reduction of molded products are progressing, and further performance improvement of molding materials is required. Among them, the development of a polycarbonate resin with high flame retardancy even in thin walls has come to be desired, and several proposals have been made.

[0003] For example, in Patent Document 1, a method for producing a polycarbonate resin using a dihydroxy compound containing a specific compound in a specific amount is adopted, and a polycarbonate resin with high flame retardancy, good color tone, high heat resistance, and few foreign matters is described.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the conventionally known techniques, it has not been possible to obtain a flame-retardant aromatic polycarbonate resin that achieves a flame retardancy level of V-0 in a vertical burning test based on UL Standard 94 without having a flame retardant.

[0006] The object of the present invention is to provide a flame-retardant aromatic polycarbonate resin and molded articles made therefrom that have high flame retardancy without the presence of flame retardants, as well as good heat resistance and transparency. [Means for solving the problem]

[0007] The inventors of this invention conducted extensive research to achieve this objective and, as a result, discovered that a polycarbonate resin having a specific structure can solve the aforementioned problem, leading to the present invention. That is, the present invention is as follows.

[0008] (1) A flame-retardant aromatic polycarbonate resin composed of repeating structural units represented by the following formulas (1) and (2), wherein the molar ratio of the repeating structural units represented by formula (1) is greater than 70% and less than 100%, and the weight-average molecular weight is between 10,000 and 100,000. [ka] [ka]

[0009] (2) The flame-retardant aromatic polycarbonate resin described in item (1) above, wherein the total light transmittance of the polycarbonate resin is 85% or more. (3) Flame-retardant aromatic polycarbonate resin as described in item (1) or (2) above, used for 3D printing. (4) Flame-retardant aromatic polycarbonate resin as described in item (3) above, used for 3D printers, in the form of filaments with a diameter of 0.2 to 5.0 mm. (5) A molded article formed from the flame-retardant aromatic polycarbonate resin described in item (1) or (2) above. (6) The molded product described in item (5) above, wherein the molded product is a 3D printed product. (7) The molded product described in item (6) above, wherein the molded product is a 3D printed product formed by the fusion deposition modeling method. (8) A flame-retardant insulating sheet or film formed from the flame-retardant aromatic polycarbonate resin described in paragraph (1) or (2) above. (9) An electric or electronic device using the flame-retardant insulating sheet or film described in the preceding paragraph (8).

Advantages of the Invention

[0010] The flame-retardant aromatic polycarbonate resin of the present invention has flame retardancy without containing a flame retardant by limiting a specific structure within a narrow range, and is also excellent in heat resistance and transparency. These technologies are not available in conventional flame-retardant technologies. The flame-retardant aromatic polycarbonate resin of the present invention can impart high flame retardancy without using fluorine compounds, which are considered to be subject to strengthened regulations in the future. It is extremely useful for various industrial applications such as the OA equipment field and the electric and electronic equipment field, and the industrial effect it exhibits is extremely large.

Modes for Carrying Out the Invention

[0011] The present invention will be described in more detail.

[0012] <Flame-Retardant Aromatic Polycarbonate Resin> The flame-retardant aromatic polycarbonate resin in the present invention is a polycarbonate resin composed of repeating structural units represented by the following formula (1) and the following formula (2), and the molar ratio of the repeating structural unit represented by the formula (1) is more than 70% and less than 100%. Preferably, it is 75% to 99%, more preferably 78% to 95%, and even more preferably 80% to 90%. If it is lower than the above lower limit, satisfactory flame retardancy cannot be obtained. Also, by adjusting the molar ratio of the repeating structural unit represented by the formula (1), it is possible to adjust the glass transition temperature.

[0013]

Chemical Formula

[0014]

Chemical Formula

[0015] The molecular weight of the flame-retardant aromatic polycarbonate resin of the present invention, as the molecular weight in terms of standard polystyrene measured by GPC (gel permeation chromatography), has a weight average molecular weight (Mw) of 10,000 to 100,000, preferably 20,000 to 90,000, more preferably 30,000 to 80,000, still more preferably 40,000 to 75,000, and particularly preferably 50,000 to 70,000.

[0016] The total light transmittance of the molded plate with a thickness of 2.0 mm of the flame-retardant aromatic polycarbonate resin of the present invention is preferably 85% or more, more preferably 86% or more, still more preferably 87% or more. The upper limit is not particularly limited, but 92% or less is sufficient. Also, the Haze value of the molded plate with a thickness of 2.0 mm of the flame-retardant aromatic polycarbonate resin of the present invention is preferably 5% or less, more preferably 4% or less, still more preferably 3% or less, and particularly preferably 2.5% or less. The lower limit is not particularly limited, but 1% or more is sufficient.

[0017] The flame-retardant aromatic polycarbonate resin of the present invention is obtained by reacting a dihydroxy compound with a carbonate precursor. Examples of the reaction method include interfacial polycondensation method, melt transesterification method, solid-phase transesterification method of carbonate prepolymer, and ring-opening polymerization method of cyclic carbonate compound. In the case of interfacial polycondensation, a monohydric phenol terminal stopper is usually used.

[0018] In a reaction using, for example, phosgene as a carbonate precursor substance, the reaction is usually carried out in the presence of an acid binder and a solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used. As the solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. Also, a catalyst such as a tertiary amine or a quaternary ammonium salt can be used to promote the reaction. At that time, the reaction temperature is usually 0 to 40°C, and the reaction time is several minutes to 5 hours.

[0019] Transesterification reactions using, for example, diester carbonate as a carbonate precursor are carried out by heating and stirring a predetermined proportion of aromatic dihydroxy components with the diester carbonate under an inert gas atmosphere, and distilling off the resulting alcohol or phenol. The reaction temperature varies depending on the boiling point of the resulting alcohol or phenol, but is usually in the range of 120 to 300°C. The reaction is completed by reducing the pressure from the beginning and distilling off the resulting alcohol or phenol. A catalyst commonly used in transesterification reactions can also be used to accelerate the reaction. Examples of diester carbonates used in the transesterification reaction include diphenyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. Of these, diphenyl carbonate is particularly preferred.

[0020] Monofunctional phenols, commonly used as end-terminating agents, can be used. In particular, in reactions using phosgene as a carbonate precursor, monofunctional phenols are generally used as end-terminating agents to adjust molecular weight, and the resulting polycarbonate resin has superior thermal stability compared to those that are not, because its ends are sealed by groups based on monofunctional phenols. Specific examples of the monofunctional phenols include, for example, phenol, m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, 1-phenylphenol, 2-phenylphenol, p-tert-butylphenol, p-cumylphenol, isooctylphenol, and p-long-chain alkylphenols.

[0021] <Other ingredients> The flame-retardant aromatic polycarbonate resin of the present invention may be blended with other resins to impart various functions or improve the properties of the molded article; however, the type and amount of other resins should be carefully considered so as not to impair the objectives of the present invention.

[0022] The flame-retardant aromatic polycarbonate resin of the present invention may contain additives such as heat stabilizers, plasticizers, light stabilizers, polymerization metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, antioxidants, ultraviolet absorbers, and mold release agents, as needed, to impart various functions to molded articles and improve their properties.

[0023] <Regarding the manufacture of flame-retardant aromatic polycarbonate resin compositions> Any method can be used to produce a flame-retardant aromatic polycarbonate resin composition by blending the flame-retardant aromatic polycarbonate resin of the present invention with other resins and additives. For example, one method involves thoroughly mixing the aromatic polycarbonate resin component with other resins and additive components using pre-mixing means such as a V-type blender, Henschel mixer, mechanochemical device, or extruder, then granulating the mixture using an extruder or briquetting machine as needed, followed by melt-kneading in a melt-kneader such as a vented twin-screw extruder, and finally pelletizing using equipment such as a pelletizer. Alternatively, other methods include supplying the aromatic polycarbonate resin component and other components independently to a melt-kneader such as a vented twin-screw extruder, pre-mixing the aromatic polycarbonate resin component and some of the other components, and then supplying them independently to the melt-kneader with the remaining components, diluting and mixing the other components with water or an organic solvent as needed before supplying them to the melt-kneader, or pre-mixing such a diluted mixture with the other components before supplying it to the melt-kneader. Furthermore, if any of the ingredients to be blended are liquid, a so-called liquid injection device or liquid additive device can be used to supply them to the melting and mixing machine.

[0024] <Flame-retardant aromatic polycarbonate resin in filament form> The flame-retardant aromatic polycarbonate resin of the present invention is preferably in the form of a filament when used as a material for 3D printed articles, as described later. By being in the form of a filament, it can be suitably used as a molding material for fused deposition modeling (FDM) 3D printers. The filament can be monofilament or multifilament, but monofilament is preferred. Furthermore, the filament may or may not be stretched.

[0025] The filament shape is preferably such that the diameter is 0.2 to 5.0 mm, more preferably 1.5 to 3.2 mm, and even more preferably 1.6 to 3.1 mm. If the diameter of the filament is below the lower limit, it may become too thin and unsuitable for general-purpose fused deposition modeling (FDM) 3D printers. The upper limit of the diameter of a filament-like molded body suitable for general-purpose FDM 3D printers is approximately the upper limit mentioned above (for example, 5.0 mm).

[0026] <Manufacturing of molded products> The flame-retardant aromatic polycarbonate resin of the present invention can be used to manufacture various products by obtaining molded articles through injection molding or 3D printing. In injection molding, it is possible to manufacture not only using the conventional cold runner method but also using a hot runner that enables runnerless production. Furthermore, in injection molding, in addition to conventional molding methods, gas-assisted injection molding, injection compression molding, ultra-high-speed injection molding, injection press molding, two-color molding, sandwich molding, in-mold coating molding, insert molding, foam molding (including those using supercritical fluids), rapid heating and cooling mold molding, in-mold remelting molding, and molding methods consisting of combinations thereof can be used. In 3D printing, fused deposition modeling and the like can be used. Furthermore, the flame-retardant aromatic polycarbonate resin of the present invention can also be molded into a product by rotational molding without melting and kneading.

[0027] Furthermore, molded products formed from flame-retardant aromatic polycarbonate resin can undergo various surface treatments. These include decorative coatings, hard coatings, water-repellent / oil-repellent coatings, hydrophilic coatings, UV-absorbing coatings, infrared-absorbing coatings, electromagnetic wave-absorbing coatings, heat-generating coatings, antistatic coatings, static-resistant coatings, conductive coatings, and metallizing (plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), thermal spraying, etc.). Products coated with a transparent conductive layer on a transparent sheet are particularly preferred.

[0028] <Flame-retardant insulating sheet or film> The method for producing a flame-retardant insulating sheet or film using the flame-retardant aromatic polycarbonate resin of the present invention is not particularly limited, but methods such as calendering, extrusion, pressing, and casting can be used.

[0029] There are no specific requirements regarding the thickness of the flame-retardant insulating sheet or film, but it is preferably 10 μm to 500 μm, and more preferably 25 μm to 250 μm.

[0030] The resulting flame-retardant insulating sheet or film can be used in electrical and electronic equipment where flame retardancy is required. [Examples]

[0031] The present invention will be further described in detail by the following examples, but the present invention is not limited thereto. The evaluation was performed according to the following method.

[0032] Evaluation Method (i) Glass transition temperature (Tg) The obtained resin was measured using a TA Instruments Discovery SDT650 differential thermal and thermogravimetric analyzer under a nitrogen atmosphere at a heating rate of 20°C / min. Approximately 5 mg of sample was used for the measurement. (ii) Transparency of the molded sheet A 2.0 mm thick molded plate of the obtained resin was formed, and the total light transmittance and turbidity (haze) were measured using a color and turbidity simultaneous measuring instrument (COH400, manufactured by Nippon Denshoku Industries Co., Ltd.). (iii) Weight average molecular weight (Mw) The molecular weight distribution was measured using gel permeation chromatography (GPC) under the following conditions, and the weight-average molecular weight (Mw) was determined. A solution was prepared by dissolving 10 mg of the obtained resin in 5 mL of chloroform. (Measurement conditions) Equipment: HLC-8420 manufactured by Tosoh Corporation Column: TSKgel SupermultiporeHZM-M x 3 + TSKgel guardcolumn (manufactured by Tosoh Corporation) Flow rate: 0.350mL / min Detection conditions: UV254nm Column temperature: 40.0℃ Eluent: Chloroform (iv)Flame retardant A vertical combustion test according to UL standard 94 was conducted on a 1.6 mm thick sample, and its grade was evaluated. If the result did not meet any of the criteria for V-0, V-1, or V-2, it will be indicated as "not V" here.

[0033] [Example 1] 155.91 parts by mass of 4,4'-(m-phenylenediisopropylidene)diphenol (bisphenol M, sometimes abbreviated as M in Table 1), 11.4 parts by mass of 2,2-bis(4-hydroxyphenyl)propane (bisphenol A, sometimes abbreviated as A in Table 1), 112.47 parts by mass of diphenyl carbonate, and 2.8 × 10⁻¹ of potassium hydroxide at a concentration of 12.5 mmol / L as a catalyst. 4 4.6 × 10⁻¹ of tetramethylammonium hydroxide at a concentration of 274 mmol / L by mass. 3Parts by mass were added and heated to 180°C under a nitrogen atmosphere to melt. Then, the pressure was adjusted to 13.4 kPa over 5 minutes. Subsequently, the temperature was increased to 270°C at a heating rate of 45°C / hr. During this time, the pressure was also gradually reduced to 1 kPa. After that, the temperature was increased to 280°C and the pressure was reduced to 100 Pa. The polymerization reaction was carried out until the predetermined power was reached, and after the reaction was completed, the resin mass was removed from the flask. The removed resin mass was pulverized using a DAS type pulverizer (DAS-14, manufactured by Daiko Co., Ltd.). Subsequently, using the pulverized resin, 1.6 mm test pieces for vertical flame retardancy evaluation and 2 mm thick test pieces for transmittance measurement were molded using a vacuum compression molding machine (SFV-10, manufactured by Shinto Metal Industry Co., Ltd.). The flame-retardant aromatic polycarbonate resin and molded pieces were evaluated for Mw, Tg, flame retardancy, and transparency of the molded plates, and the results are shown in Table 1.

[0034] [Example 2, Comparative Examples 1-3] Polycarbonate resin was manufactured in the same manner as in Example 1, except that the amounts of each monomer were changed to the amounts shown in Table 1. A 1.6 mm thick test piece for vertical flame retardancy evaluation and a 2 mm thick test piece for transmittance measurement were molded. Using the polycarbonate resin and molded pieces, Mw, Tg, flame retardancy, and transparency of the molded sheet were evaluated, and the results are shown in Table 1.

[0035] [Table 1]

[0036] From the comparison between the examples and comparative examples in Table 1, it can be seen that the flame-retardant aromatic polycarbonate resin of the present invention exhibits high flame retardancy even without the presence of flame retardants, as well as good heat resistance and transparency. [Industrial applicability]

[0037] The flame-retardant aromatic polycarbonate resin of the present invention possesses flame retardancy without containing flame retardants by limiting its specific structure to a narrow range. This property is not found in conventional flame-retardant aromatic polycarbonate resins. Therefore, the flame-retardant aromatic polycarbonate resin of the present invention is extremely useful not only for lighting covers and protective covers for transmissive displays, but also for various industrial applications in fields such as office automation equipment and electrical and electronic equipment, and the industrial effects it provides are extremely significant.

Claims

1. A flame-retardant aromatic polycarbonate resin composed of repeating structural units represented by the following formulas (1) and (2), wherein the molar ratio of the repeating structural units represented by formula (1) is greater than 70% and less than 100%, and the weight-average molecular weight is between 10,000 and 100,000. 【Chemistry 1】 【Chemistry 2】

2. The flame-retardant aromatic polycarbonate resin according to claim 1, wherein the total light transmittance of the polycarbonate resin is 85% or more.

3. A flame-retardant aromatic polycarbonate resin according to claim 1, used for 3D printing.

4. The flame-retardant aromatic polycarbonate resin according to claim 3, used for 3D printers with a filament shape having a diameter of 0.2 to 5.0 mm.

5. A molded article formed from the flame-retardant aromatic polycarbonate resin described in claim 1.

6. The molded product according to claim 5, wherein the molded product is a 3D printed product.

7. The molded product according to claim 6, wherein the molded product is a 3D printed product formed by a fused deposition modeling method.

8. A flame-retardant insulating sheet or film formed from the flame-retardant aromatic polycarbonate resin described in claim 1.

9. Electrical and electronic equipment using the flame-retardant insulating sheet or film described in claim 8.

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