JP7845849B2 - Flame-retardant polycarbonate resin composition - Google Patents

Description

This invention relates to a flame-retardant polycarbonate resin composition, and more specifically, to a flame-retardant polycarbonate resin composition that meets the PFBS regulations and complies with the PFAS regulations, and possesses excellent flame retardancy.

Polycarbonate resin is a resin with excellent heat resistance, mechanical properties, and electrical properties, and is widely used as a material for manufacturing parts in various industrial fields, such as vehicle parts, electrical and electronic equipment components, housing materials, and other industrial sectors. In particular, flame-retardant polycarbonate resin compositions are suitably used as parts for vehicle components, electrical and electronic equipment components such as personal computers, mobile phones, and battery cases, and office automation and information equipment such as printers and photocopiers.

Halogen-based flame retardants have traditionally been used to impart flame retardancy to polycarbonate resins, and in recent years, phosphorus-based flame retardants and organic sulfonic acid metal salt-based flame retardants have been used. When these flame retardants are combined with polyfluoroethylene as a drip-preventing agent, dripping is suppressed and flame retardancy can be improved, and the applicant has made various proposals for this purpose.
For example, Patent Document 1 proposes a flame-retardant polycarbonate resin composition containing an aromatic polycarbonate resin, a specific core-shell type graft copolymer with a butadiene rubber core, a fluorinated polyolefin, and an organic sulfonic acid metal salt-based flame retardant, specifically potassium perfluorobutanesulfonate.

However, in recent years, fluorinated compounds have become subject to international regulations, primarily in Japan, Europe, and the United States, and there are moves to further strengthen these regulations. In the EU, perfluorobutanesulfonic acid and its metal salts (PFBS) are regulated under REACH, and it is predicted that these regulations will be strengthened and banned within a few years. Furthermore, PFAS regulations for perfluoro and polyfluoroalkyl compounds are progressing, mainly in the EU and the United States. While currently focused on specific sectors such as food and textiles, there is a possibility of these regulations spreading to other fields.

Japanese Patent Publication No. 2019-19191

Therefore, in order to comply with the aforementioned PFBS and PFAS regulations, there is a strong demand for polycarbonate resin compositions that exhibit excellent flame retardancy without relying on perfluorobutanesulfonic acid metal salts or polytetrafluoroethylene. However, polytetrafluoroethylene is an effective drip inhibitor, and achieving V-0 in the UL-94 test without it is not easy.
This invention has been made in view of the above circumstances, and its objective (problem) is to provide a flame-retardant polycarbonate resin composition that has excellent flame retardancy, clears the PFBS regulations and complies with the PFAS regulations.

The inventors of the present invention have conducted extensive research to achieve the above objectives and have found that the above objectives can be solved by combining a polycarbonate resin consisting of 40 to 100% by mass of recycled polycarbonate resin and 60 to 0% by mass of virgin polycarbonate resin with a non-fluorine-based organic sulfonic acid-based flame retardant composition, thereby completing the present invention.
This invention relates to the following flame-retardant polycarbonate resin compositions and molded articles.

[1] (A) Polycarbonate resin consisting of 40 to 100% by mass of recycled polycarbonate resin (A1) and 60 to 0% by mass of virgin polycarbonate resin (A2), with (B) 0.05 to 0.3 parts by mass of an organic sulfonic acid-based flame retardant that does not contain fluorine, and (C) Polytetrafluoroethylene is not contained, or if it is contained, the content is 0.09 parts by mass or less.
A flame-retardant polycarbonate resin composition characterized in that the amount of perfluorobutanesulfonic acid and its metal salt (PFBS) in the resin composition is less than 10 ppm, and the amount of polyfluoroalkyl compound (PFAS) is less than 1000 ppm.
[2] (B) The flame-retardant polycarbonate resin composition according to [1] above, wherein the organic sulfonic acid-based flame retardant is one or more of the following: p-toluenesulfonic acid or its metal salt, phenylsulfonylbenzenesulfonic acid or its metal salt, or polystyrenesulfonic acid or its metal salt.
[3] A molded article of the flame-retardant polycarbonate resin composition described in [1] or [2] above.

The flame-retardant polycarbonate resin composition of the present invention meets the PFBS regulations and complies with the PFAS regulations, exhibiting excellent flame retardancy.
To comply with PFBS and PFAS regulations, it is necessary to eliminate or reduce compounds containing C-F bonds from the composition. In other words, it is necessary to eliminate or reduce the amount of fluorine-containing flame retardants such as PFBS and polytetrafluoroethylene, which is useful as a drip-preventing agent. In such cases, flame retardancy usually deteriorates. Specifically, in the UL94 vertical combustion test, the burning time is extended and dripping occurs. To improve this, the inventor continued diligent research and found that by blending a certain percentage or more of recycled polycarbonate resin into the base polycarbonate resin, the burning time is shortened, resulting in the development of high flame retardancy. It is presumed that trace components mixed in during the manufacturing process of recycled polycarbonate resin contribute to the shortening of the burning time, but the details are still under investigation.

The present invention will be described in detail below with reference to embodiments and examples.
In this specification, unless otherwise specified, "~" means that the numbers before and after it are included as the lower and upper limits, respectively.

The flame-retardant polycarbonate resin composition of the present invention comprises (A) 100 parts by mass of polycarbonate resin consisting of 40 to 100% by mass of recycled polycarbonate resin (A1) and 60 to 0% by mass of virgin polycarbonate resin (A2), (B) 0.05 to 0.3 parts by mass of an organic sulfonic acid-based flame retardant that does not contain fluorine, and (C) polytetrafluoroethylene is not contained, or if it is contained, the content is 0.09 parts by mass or less.
The resin composition is characterized by having an amount of perfluorobutanesulfonic acid and its metal salt (PFBS) of less than 10 ppm and an amount of polyfluoroalkyl compound (PFAS) of less than 1000 ppm.
The present invention will be described in detail below.

[(A) Polycarbonate resin]
The polycarbonate resin (A) used in the present invention consists of 40 to 100% by mass of recycled polycarbonate resin (A1) and 60 to 0% by mass of virgin polycarbonate resin (A2).

The polycarbonate resins (A1) and (A2) are preferably aromatic polycarbonate resins. Aromatic polycarbonate resins are aromatic polycarbonate polymers obtained by reacting an aromatic dihydroxy compound with a phosgene or carbonic acid diester. The method for producing the aromatic polycarbonate resin is not particularly limited and may be any method such as the phosgene method (interfacial polymerization method) or the melting method (transesterification method).

Representative aromatic dihydroxy compounds include, for example, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-t-butylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 4,4-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxybiphenyl, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)ether, and bis(4-hydroxyphenyl)ketone.

Among the aromatic dihydroxy compounds mentioned above, those starting from 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) or 2,2-bis(4-hydroxy-3-methylphenyl)propane (i.e., bisphenol C) are preferred, and those starting from bisphenol A are particularly preferred.
Furthermore, the above-mentioned aromatic dihydroxy compounds may be used individually or as a mixture of two or more types.

In this invention, the polycarbonate resins (A1) and (A2) are preferably obtained by either interfacial polymerization or transesterification.

<Recycled polycarbonate resin (A1)>
By including recycled polycarbonate resin (A1) as a standalone component in (A) polycarbonate resin at a concentration of 40% by mass or more, the flame extinguishing time after exposure to flame can be shortened, and a high level of flame retardancy can be achieved.

Recycled polycarbonate resin (A1) is polycarbonate resin recovered from molded products using polycarbonate resin as a base material. It is a material recycled material also known as market-recovered polycarbonate resin, recovered, or recycled polycarbonate resin. It may be polycarbonate resin recovered from used molded products that have been shipped to the market, or polycarbonate resin recovered from waste materials, scraps, or defective products generated during the manufacturing process of molded products. Note that so-called chemically recycled products, where polycarbonate resin is returned to its starting raw materials before being made into polycarbonate resin, do not fall under recycled polycarbonate resin (A1), but rather correspond to virgin polycarbonate resin (A2).

Preferred types of molded products from which polycarbonate resin is recovered include beverage containers such as water bottles for water dispensers, baby bottles, and water bottles; optical components such as headlamps, camera lenses, light guide plates, and transparent covers for electrical components in vehicles such as automobiles; cases and housings for electronic components in pachinko machines, etc.; sheets; building materials such as corrugated sheets and carport panels; semiconductor transport containers; and optical recording media such as CDs and DVDs. Among these, recycled polycarbonate resin recovered from headlamp lenses, sheets, transparent covers for electrical components, water bottles, semiconductor transport containers, optical discs, and pachinko machine parts is particularly preferred.

Recycled polycarbonate resin (A1) may be used alone or in a mixture of two or more types.

The recycled polycarbonate resin (A1) is preferably derived from polycarbonate resin collected from the market.

The molecular weight of the recycled polycarbonate resin (A1) is calculated as the viscosity-average molecular weight (Mv) from the solution viscosity measured at 25°C using methylene chloride as the solvent. Preferably, it is 13,000 or higher, more preferably 15,000 or higher, even more preferably 18,000 or higher, particularly 20,000 or higher, preferably 50,000 or lower, more preferably 40,000 or lower, even more preferably 36,000 or lower, and particularly preferably 33,000 or lower.

The viscosity-average molecular weight [Mv] of polycarbonate resin refers to the value calculated using Schnell's viscosity formula, i.e., η = 1.23 × ^10⁻⁴ Mv ^0.83 , by determining the intrinsic viscosity [η] (unit dl/g) at 25°C using an Ubbelohde viscometer with methylene chloride as the solvent. Furthermore, the intrinsic viscosity [η] is the value calculated by measuring the specific viscosity [η _sp ] at each solution concentration [C] (g/dl) and using the following formula.

<Virgin polycarbonate resin (A2)>
Virgin polycarbonate resin (A2) is polycarbonate resin that is not used in the manufacture of molded products (virgin), other than recycled polycarbonate resin (A1).

The virgin polycarbonate resin (A2) has the same raw material components and polymerization method as described above. The virgin polycarbonate resin (A2) is preferably an aromatic polycarbonate resin, more preferably one starting from bisphenol A or bisphenol C, and particularly preferably one starting from bisphenol A.

The content of virgin polycarbonate resin (A2) is 60 to 0% by mass in polycarbonate resin (A), and polycarbonate resin (A1) is 40 to 100% by mass, preferably (A1) 45 to 100% by mass, (A2) 55 to 0% by mass, more preferably (A1) 50 to 100% by mass, (A2) 50 to 0% by mass, even more preferably (A1) 55 to 100% by mass, and (A2) 45 to 0% by mass. It is also preferable that (A1) be 50 to 95% by mass and (A2) be 50 to 5% by mass, more preferably (A1) 50 to 90% by mass and (A2) 50 to 10% by mass, and even more preferably (A1) 55 to 80% by mass and (A2) 45 to 20% by mass.

The molecular weight of virgin polycarbonate resin (A2) is calculated as the viscosity-average molecular weight (Mv) from the solution viscosity measured at 25°C using methylene chloride as the solvent. Preferably, it is 15,000 or more, more preferably 18,000 or more, particularly 20,000 or more, preferably 40,000 or less, more preferably 36,000 or less, and particularly preferably 33,000 or less.

[(B) Fluorine-free organic sulfonic acid-based flame retardants]
The flame-retardant polycarbonate resin composition of the present invention contains (B) a fluorine-free organic sulfonic acid flame retardant. The content of (B) the fluorine-free organic sulfonic acid flame retardant is 0.05 to 0.3 parts by mass, preferably 0.05 to 0.25 parts by mass, and more preferably 0.05 to 0.2 parts by mass, per 100 parts by mass of (A) polycarbonate resin. By combining (A) polycarbonate resin in such amounts, a flame-retardant polycarbonate resin composition can be obtained that clears PFBS regulations, complies with PFAS regulations, and exhibits excellent flame retardancy.

(B) As a fluorine-free organic sulfonic acid-based flame retardant, a non-fluorine organic sulfonic acid or its metal salt that does not have a C-F bond in its molecule is preferred.

The metal in the metal salt is preferably an alkali metal or an alkaline earth metal. Examples include alkali metals such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs); and alkaline earth metals such as magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Among these, sodium, potassium, and cesium are preferred, with sodium and potassium being particularly preferred.

Preferred non-fluorinated organic sulfonic acids or their metal salts include aromatic sulfonic acids or their metal salts, aromatic sulfonamides (or sulfonimides) or their metal salts, and polystyrene sulfonic acids or their metal salts; more preferably, these metal salts.

Specific examples of these include alkali metal salts of aromatic sulfonic acids having at least one aromatic group in their molecule, such as potassium 3-(phenylsulfonyl)benzenesulfonate (i.e., potassium diphenylsulfon-3-sulfonate), dipotassium diphenylsulfon-3,3'-disulfonate, sodium benzenesulfonate, potassium benzenesulfonate, cesium benzenesulfonate, sodium p-toluenesulfonate, potassium p-toluenesulfonate, cesium p-toluenesulfonate, sodium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate, cesium dodecylbenzenesulfonate, potassium styrenesulfonate, sodium polystyrenesulfonate, potassium polystyrenesulfonate, and cesium polystyrenesulfonate;
Examples include alkaline earth metal salts of aromatic sulfonic acids having at least one aromatic group in their molecule, such as magnesium p-toluenesulfonate, calcium p-toluenesulfonate, strontium p-toluenesulfonate, barium p-toluenesulfonate, magnesium dodecylbenzenesulfonate, and calcium dodecylbenzenesulfonate.

Examples of metal salts of aromatic sulfonamides (or sulfonimides) include the potassium salt of N-(p-tolylsulfonyl)-p-toluenesulfoimide, the potassium salt of N-(N'-benzylaminocarbonyl)sulfanilimide, and the potassium salt of N-(phenylcarboxyl)-sulfanilimide.

(B) Among the above-mentioned organic sulfonic acid-based flame retardants that do not contain fluorine, p-toluenesulfonic acid or its metal salt, phenylsulfonylbenzenesulfonic acid or its metal salt, and polystyrenesulfonic acid or its metal salt are preferred, and among these, their metal salts, particularly alkali metal salts, are preferred.

(B) Fluorine-free organic sulfonic acid flame retardants may be used individually or in combination of two or more types in any combination and ratio.

[(C) Polytetrafluoroethylene]
The flame-retardant polycarbonate resin composition of the present invention does not contain (C) polytetrafluoroethylene, or if it does contain it, the amount is 0.09 parts by mass or less per 100 parts by mass of (A) polycarbonate resin. Polytetrafluoroethylene having fibril-forming ability has been used as a sagging prevention agent, but in the present invention, a flame-retardant polycarbonate resin composition compliant with PFAS regulations can be made by not containing (C) polytetrafluoroethylene, or if it does contain it, the amount is 0.09 parts by mass or less as described above.

[Other resin components]
The flame-retardant polycarbonate resin composition of the present invention may contain (A) a fluorine-free resin other than polycarbonate resin, to the extent that it does not impair the effects of the present invention.
Examples include thermoplastic polyester resins such as polyethylene terephthalate resin, polytrimethylene terephthalate resin, and polybutylene terephthalate resin; styrene-based resins such as polystyrene resin, high-impact polystyrene resin (HIPS), acrylonitrile-styrene-acrylic rubber copolymer (ASA resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and acrylonitrile-butadiene-styrene copolymer (ABS resin); polyolefin resins such as polyethylene resin and polypropylene resin; polyamide resin; polyimide resin; polyetherimide resin; polyurethane resin; polyphenylene ether resin; polyphenylene sulfide resin; and polysulfone resin. Note that other resins may be present individually, or two or more in any combination and ratio.
If other resins are included, it is preferable that the amount is 30 parts by mass or less per 100 parts by mass of (A) polycarbonate resin, and more preferably 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, 7 parts by mass or less, 5 parts by mass or less, 3 parts by mass or less, and especially 1 part by mass or less.

[Other additives]
The flame-retardant polycarbonate resin composition of the present invention may further contain additives other than those described above, as long as they do not impair the effects of the present invention. Examples of such additives include stabilizers, mold release agents, ultraviolet absorbers, antistatic agents, dyes and pigments, antifogging agents, lubricants, antiblocking agents, sliding modifiers, impact resistance modifiers, plasticizers, dispersants, and antibacterial agents. These additives must not contain fluorine.

[Stabilizer]
The flame-retardant polycarbonate resin composition of the present invention may also contain a stabilizer, and phosphorus-based stabilizers or phenol-based stabilizers are preferred.

Any known phosphorus-based stabilizer can be used. Specific examples include phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphate (phospho oxoacids); acidic pyrophosphate metal salts such as sodium acidic pyrophosphate, potassium acidic pyrophosphate, and calcium acidic pyrophosphate; phosphates of Group 1 or Group 2B metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; and organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds, although organic phosphite compounds and organic phosphate compounds are particularly preferred.

Examples of organic phosphite compounds include triphenyl phosphite, tris(mononylphenyl) phosphite, tris(mononyl/dinonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, monooctyldiphenyl phosphite, dioctylmonophenyl phosphite, monodecyldiphenyl phosphite, didecylmonophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, and 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite.
Examples of such organic phosphite compounds include, for example, "ADEKA Stab 1178,""ADEKA Stab 2112," and "ADEKA Stab HP-10" manufactured by ADEKA Corporation, "JP-351,""JP-360," and "JP-3CP" manufactured by Johoku Chemical Industry Co., Ltd., and "Irgaphos 168" manufactured by BASF.

Suitable organic phosphate compounds include metal salts of organic phosphates. Specifically, examples include mixtures of zinc salts of distearyl acid phosphate and zinc salts of monostearyl acid phosphate, monostearyl acid phosphate, and distearyl acid phosphate.
Examples of such organic phosphate metal salts include, for instance, "JP-518Zn" manufactured by Johoku Chemical Industry Co., Ltd. and "AX-71" manufactured by ADEKA Corporation.

Furthermore, the phosphorus-based stabilizer may be present in any combination and ratio, or two or more types may be present.

The phosphorus-based stabilizer content is typically 0.001 parts by mass or more, preferably 0.01 parts by mass or more, and more preferably 0.03 parts by mass or more, per 100 parts by mass of (A) polycarbonate resin, and typically 1 part by mass or less, preferably 0.7 parts by mass or less, and more preferably 0.5 parts by mass or less. If the phosphorus-based stabilizer content is below the lower limit of the above range, the thermal stabilization effect may be insufficient. If the phosphorus-based stabilizer content exceeds the upper limit of the above range, the effect may plateau, making it uneconomical.

Examples of phenolic stabilizers include hindered phenolic antioxidants. Specific examples include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 2,4-dimethyl-6-(1-methylpentadecyl)phenol, diethyl[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphoate, 3,3',3”,5,5',5”-hexa-tert-butyl-a,a',a”-(mesitylene-2,4,6- Examples include triyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate.

Among these, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferred.
Examples of such phenolic antioxidants include, for instance, BASF's "Irganox 1010" and "Irganox 1076," and ADEKA's "ADEKA Stab AO-50" and "ADEKA Stab AO-60."
Furthermore, the phenolic stabilizer may be present in any combination and ratio, or in any combination of two or more types.

The content of the phenolic stabilizer is typically 0.001 parts by mass or more, preferably 0.01 parts by mass or more, and typically 1 part by mass or less, preferably 0.5 parts by mass or less, per 100 parts by mass of (A) polycarbonate resin. If the content of the phenolic stabilizer is below the lower limit of the above range, the effect of the phenolic stabilizer may be insufficient. If the content of the phenolic stabilizer exceeds the upper limit of the above range, the effect may plateau, making it uneconomical.

[Release agent]
The flame-retardant polycarbonate resin composition of the present invention preferably contains a mold release agent. While known mold release agents commonly used for resins can be used, polyolefin compounds and fatty acid ester compounds are preferred.

Examples of polyolefin compounds include those selected from paraffin wax and polyethylene wax, with a preferred weight-average molecular weight of 700 to 10,000, and more preferably 900 to 8,000.

Examples of fatty acid ester compounds include saturated or unsaturated monovalent or divalent aliphatic carboxylic acid esters, glycerol fatty acid esters, sorbitan fatty acid esters, and other fatty acid esters, as well as their partially saponified products. Among these, mono- or di-fatty acid esters composed of a fatty acid having 11 to 28 carbon atoms, preferably 17 to 21 carbon atoms, and an alcohol are preferred.

Examples of fatty acids include palmitic acid, stearic acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melissic acid, tetrariacontanoic acid, montanic acid, adipic acid, and azelaic acid. Furthermore, fatty acids may also be alicyclic.
Examples of alcohols include saturated or unsaturated monohydric or polyhydric alcohols. These alcohols may have substituents such as aryl groups. Among these, monohydric or polyhydric saturated alcohols having 30 or fewer carbon atoms are preferred, and aliphatic saturated monohydric or polyhydric alcohols having 30 or fewer carbon atoms are more preferred. Here, "aliphatic" includes alicyclic compounds.
Specific examples of such alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol.
The above-mentioned ester compounds may contain aliphatic carboxylic acids and/or alcohols as impurities, and may also be mixtures of multiple compounds.

Specific examples of fatty acid ester compounds include glycerin monostearate, glycerin monobehenate, glycerin dibehenate, glycerin-12-hydroxymonostearate, sorbitan monobehenate, pentaerythritol monostearate, pentaerythritol distearate, stearyl stearate, and ethylene glycol montanate.

The release agent content is preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2.5 parts by mass, and even more preferably 0.25 to 2 parts by mass, per 100 parts by mass of (A) polycarbonate resin. If the content is less than 0.1 parts by mass, surface quality tends to deteriorate due to poor release during melt molding. On the other hand, if it exceeds 3 parts by mass, the kneading workability of the resin composition tends to deteriorate, and clouding is likely to occur on the surface of the molded article.

[Method for producing flame-retardant polycarbonate resin composition]
There are no limitations on the method for producing the flame-retardant polycarbonate resin composition of the present invention, and a wide range of known methods for producing polycarbonate resin compositions can be employed. For example, a method may be used in which recycled polycarbonate resin (A1), virgin polycarbonate resin (A2), and (B) a fluorine-free organic sulfonic acid-based flame retardant, as well as other components added as needed, are pre-mixed using various mixers such as a tumbler or Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, roll, braver, single-screw extruder, twin-screw extruder, or kneader. The melt-kneading temperature is not particularly limited, but is usually in the range of 240 to 320°C.

[Flame-retardant polycarbonate resin composition]
The flame-retardant polycarbonate resin composition of the present invention contains less than 10 ppm of perfluorobutanesulfonic acid and its metal salts (PFBS) and less than 1000 ppm of polyfluoroalkyl compounds (PFAS), thus satisfying PFBS and PFAS regulations. PFAS regulations are being implemented by the EU/REACH and the US/EPA. According to the REACH definition, PFAS is a general term for perfluoroalkyl compounds, polyfluoroalkyl compounds, and their salts, meaning it targets compounds with C-F bonds. Therefore, in the present invention, PFAS also includes PFBS and targets compounds with C-F bonds. Currently, regulatory thresholds are being considered by each community, but based on past PFBS regulations, it is assumed that a content of 1000 ppm or less will satisfy PFAS regulations.

[Molded product]
The flame-retardant polycarbonate resin composition of the present invention can be used to produce various molded products by molding pellets obtained by pelletizing the above-mentioned flame-retardant polycarbonate resin composition using various molding methods. Alternatively, the resin, which is melt-kneaded in an extruder, can be directly molded into molded products without going through the pellet stage.

To manufacture molded articles of the flame-retardant polycarbonate resin composition of the present invention, any molding method commonly used for polycarbonate resin compositions can be arbitrarily employed. Examples include injection molding, ultra-high-speed injection molding, injection compression molding, two-color molding, hollow molding methods such as gas-assisted molding, molding using insulated molds, molding using rapidly heated molds, foam molding (including supercritical fluids), insert molding, IMC (in-mold coating) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, press molding, and blow molding. Furthermore, molding methods using a hot runner system can also be employed.

There are no restrictions on the shape, pattern, color, or dimensions of the molded product; these can be arbitrarily set according to the intended use of the product.
Examples of molded products include electrical and electronic equipment, office automation equipment, information terminal equipment, machine parts, home appliances, vehicle (automobile) parts, building materials, various containers, amusement machines, leisure goods and miscellaneous items, lighting equipment parts, casings, etc.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

The raw materials used in the following examples and comparative examples are shown in Table 1 below.

(Examples 4, 7; Reference Examples 1-3, 5-6 ; Comparative Examples 1-5)
[Manufacturing of polycarbonate resin composition pellets]
Each component listed in Table 1 above was blended in the proportions (parts by mass) shown in Table 3 below, mixed in a tumbler for 20 minutes, and then supplied from the upstream feeder to a Toshiba Machine Co., Ltd. twin-screw extruder (TEM26SX) equipped with one vent. The mixture was kneaded at a rotation speed of 180 rpm, a discharge rate of 20 kg/hour, and a barrel temperature of 255°C. The molten resin extruded into strands was rapidly cooled in a water bath and pelletized using a pelletizer to obtain pellets of the polycarbonate resin composition.

[Measurement of PFBS and PFAS content (unit: mass ppm)]
The amount of PFBS in the composition was quantified by gas chromatography. Specifically, the polycarbonate resin composition obtained above was completely dissolved in methylene chloride, and then methanol was added to precipitate the polycarbonate components. The methanol-soluble PFBS was then quantified using a Shimadzu GC-2010. This method does not detect PTFE, so only PFBS can be accurately detected. The amount of PFAS in the resin composition was also quantified by combustion ion chromatography. Specifically, the polycarbonate resin composition pellets obtained above were heated in an argon atmosphere at 270°C for 10 minutes using an AQF-100 automatic sample combustion device manufactured by Mitsubishi Chemical Analytec, and the amount of F ions generated was quantified using an ICS-90 manufactured by Nippon Dionex.
In Table 3, "ND" indicates "not detected," meaning the level was below the detection limit (1 ppm) and could not be detected.

[Flame retardancy evaluation]
After drying the pellets obtained by the above manufacturing method at 120°C for 4 hours, they were injection molded using a Sumitomo Heavy Industries SE100DU injection molding machine under the conditions of a cylinder temperature of 260°C, a mold temperature of 80°C, and a molding cycle of 30 seconds to produce test pieces for UL combustion testing with a length of 125 mm, a width of 13 mm, and a thickness of 1.5 mm or 2.0 mm.

The flame retardancy was evaluated by conditioned the UL combustion test specimens obtained using the method described above in a constant temperature and humidity chamber at 23°C and 50% humidity for 48 hours, and then conducted in accordance with the UL94 test (combustion test for plastic materials for equipment components) as defined by UL in the United States.

The UL94-V test evaluates flame retardancy by measuring the afterflame time and drip rate after indirectly applying a burner flame to the lower end of a test specimen of a predetermined size, held vertically, for 10 seconds. To achieve flame retardancy of V-0, V-1, and V-2, the criteria shown in Table 2 below must be met.

Here, afterflame time refers to the length of time the test specimen continues to burn with flame after the ignition source has been removed. Furthermore, cotton ignition by drip is determined by whether the marker cotton, located approximately 300 mm below the bottom of the test specimen, is ignited by the drippings from the test specimen. In addition, if even one of the five tests for a single material fails to meet the above criteria, it is evaluated as NR (not rated) and V-2 is not satisfied.
The maximum burning time (seconds), total burning time (seconds), and number of drips are listed in Table 3 below.
The evaluation results are shown in Table 3 below.

The flame-retardant polycarbonate resin composition of the present invention complies with PFBS regulations and PFAS regulations, exhibits excellent flame retardancy, and has excellent moldability. Therefore, molded products can be suitably used in electrical and electronic equipment, office automation equipment, information terminal equipment, machine parts, home appliances, vehicle parts, building materials, various containers, amusement machines, leisure goods and miscellaneous items, lighting equipment, and other components.

Claims (2)

(A) Polycarbonate resin consisting of 40 to 100% by mass of recycled polycarbonate resin (A1) and 60 to 0% by mass of virgin polycarbonate resin (A2) is per 100 parts by mass of polycarbonate resin, (B) containing 0.05 to 0.3 parts by mass of a fluorine-free organic sulfonic acid flame retardant, (C) not containing polytetrafluoroethylene, or if it is contained, the content is 0.09 parts by mass or less, and (B) the fluorine-free organic sulfonic acid flame retardant is phenylsulfonylbenzenesulfonic acid or its metal salt.
A flame-retardant polycarbonate resin composition characterized in that the amount of perfluorobutanesulfonic acid and its metal salt (PFBS) in the resin composition is less than 10 ppm, and the amount of polyfluoroalkyl compound (PFAS) is less than 1000 ppm. A molded article of the flame-retardant polycarbonate resin composition according to claim 1 .