KR100520456B1 - Flame Retardant Thermoplastic Resin Composition - Google Patents

Abstract

Flame retardant polycarbonate-based thermoplastic resin composition of the present invention

(A) 100 parts by weight of thermoplastic polycarbonate base resin;

(B) (B ₁ ) Linear phosphazene represented by the following general formula (I-a) and / or cyclic phosphazene compound represented by the following general formula (I-b) 5 to 90 weight%; And

(In the general formulas (I-a) and (I-b), R represents a substituent optionally selected from alkyl group, aryl group, alkyl substituted aryl group, aralkyl group, alkoxy group, aryloxy group, amino group and hydroxy group. , k is 0 or an integer from 1 to 10)

(B ₂ ) 95 to 10% by weight of phosphate ester morphide flame retardant represented by the following general formula (II);

In the above formula (II), x is 1 or 2, R ₁ is C ₆ -C ₂₀ aryl or alkyl substituted C ₆ -C ₂₀ aryl group, and R ₂ is C ₆ -C ₃₀ aryl or alkyl substituted C _{6 to C 30} aryl group derivatives, n and m each represent a number average degree of polymerization, and the average value of n + m is 0 to 5).

1 to 10 parts by weight of a mixture of;

(C) 0.01-1.0 parts by weight of perfluorinated alkane sulfonate salts; And

(D) 0.05 to 5 parts by weight of a fluorinated polyolefin resin having an average particle size of 0.05 to 1000 µm and a density of 1.2 to 2.3 g / cm ³ ;

Characterized in that consists of.

Description

Flame Retardant Thermoplastic Resin Composition

Field of invention

The present invention relates to a polycarbonate-based thermoplastic resin composition excellent in flame retardancy, heat resistance and mechanical strength, and more particularly, based on a thermoplastic polycarbonate-based resin, a specific structure phosphazene compound and phosphate ester morphide-based The present invention relates to a flame retardant thermoplastic resin composition comprising a flame retardant made of a compound, a fluorine alkane sulfonate salt, and a fluorinated polyolefin-based resin, which exhibits excellent flame retardancy, heat resistance and mechanical strength, and is excellent in impact resistance, thermal stability, workability and appearance characteristics.

Background of the Invention

Polycarbonate resins have been widely used in office automation devices, electrical and electronic products as engineering plastics because of their excellent low temperature impact resistance, self-extinguishing, electrical properties, transparency, dimensional stability, thermal stability, and the like compared to other resins. In addition, since polycarbonate is generally applied to a heat-dissipating molded article such as electrical and electronic products or other office equipment, it is essential to maintain flame retardancy and high mechanical strength. In order to impart flame retardancy to such resin compositions, conventionally adding bromine or chlorine-based flame retardants is a technique well known in the conventional manner. However, when using such a bromine or chlorine-based flame retardant, the demand for a resin that does not use a bromine or chlorine-based flame retardant is expanding rapidly in recent years due to the problem of human health of the gas generated during combustion.

As a technique for imparting flame retardancy without using a halogen flame retardant, the most common at present is to use a phosphate ester flame retardant. U.S. Patent No. 4,692,488 discloses thermoplastic resin compositions consisting of non-halogen aromatic polycarbonate resins, non-halogen SAN (styrene-acrylonitrile) copolymers, non-halogen phosphorus compounds, tetrafluoroethylene polymers and small amounts of ABS copolymers. have. If phosphorus-based compounds and fluorinated alkane polymers are used to impart flame retardancy to PC / ABS blend resin compositions as in U.S. Patent No. 4,692,488, the dropping of sparks generated during combustion can be prevented. There is a problem in that the surface cracks, that is, the "juicing" phenomenon occurs by migrating to the surface of the molding.

U.S. Patent 5,061,745 discloses a flame retardant resin composition composed of an aromatic polycarbonate resin, an ABS graft copolymer, a copolymer and a monomeric phosphate ester. This composition also has the disadvantage that due to the volatilization of the monomeric phosphate ester, it may cause a surface crack problem due to the juice phenomenon, and the degradation of heat resistance is severe.

Oligomeric phosphate ester compounds are also known to be used as flame retardants, and Japanese Patent Laid-Open No. 59-202,240 discloses a process for preparing such compounds. It is also disclosed that this compound can be used as a flame retardant of polyamide or polycarbonate resins.

U.S. Patent 5,204,394 discloses flame retardant resin compositions composed of aromatic polycarbonate resins, styrene-containing copolymers or graft copolymers and phosphate ester oligomers. However, the application of the flame retardant in the form of an oligomeric condensed phosphate ester to a thermoplastic resin has advantages in that less occurrence of juice phenomenon and relatively improved heat resistance compared to the case of using a monomeric phosphate ester. When using a flame retardant has a disadvantage in that the flame retardancy is lowered, it is necessary to add a larger amount of flame retardant to secure the same level of flame retardancy. In addition, since a certain amount of monomeric phosphate ester was included, it did not completely prevent the juice phenomenon that they migrate to the surface of the molding during molding.

U.S. Patent 5,672,645 discloses PC / ABS resin compositions consisting of aromatic polycarbonate resins, vinyl copolymers, graft copolymers, mixtures of monomeric and oligomeric phosphate esters and fluorinated polyolefins. Also in this case, there is a problem in that a juice phenomenon in which the monomeric phosphate ester moves to the surface of the molding during molding occurs, a decrease in heat resistance occurs, and a flame retardancy decreases when an excessive amount of the oligomeric phosphate ester is used.

Japanese Patent Publication No. 6-100,785 discloses a technique for preventing dropping during combustion by adding a silicone resin or phosphazene to a flame retardant resin composition composed of a thermoplastic resin, a phosphorus ester compound or a red phosphorus. However, the patent does not indicate that the flame retardancy is improved by the addition of phosphazene.

EP 728,811 discloses a flame retardant resin composition composed of an aromatic polycarbonate resin, a graft copolymer, a vinyl copolymer and an oligomeric phosphazene. This patent shows that the oligomer-type phosphazene is used as a flame retardant so that no dropping occurs during combustion without a separate anti-drip agent, and excellent heat resistance and impact strength can be obtained. The workability is lowered due to the fluidity drop, and thus, when excessive stress is applied during injection, black lines and black lines are generated on the surface of the injection molded product due to decomposition of the resin or flame retardant. In addition, when the oligomeric phosphazene is used as a flame retardant, mechanical strengths such as flexural strength and flexural modulus of the resin composition are deteriorated.

The present inventors have studied diligently to solve the conventional problems, and as a result, a combination of a flame retardant mixture of a phosphazene compound and a phosphate ester morphide compound and a fluorinated alkane sulfonate salt in a polycarbonate resin is used as a flame retardant. It was found that the synergistic effect of flame retardancy was exhibited without lowering the heat resistance and mechanical strength than the case of using only a phosphazene compound and a phosphate ester morphide flame retardant, and thus, the present invention was completed.

An object of the present invention is to provide a thermoplastic resin composition exhibiting excellent flame retardancy by using a phosphazene compound, a phosphate ester morphide flame retardant and a fluorinated alkane sulfonate salt in combination with a thermoplastic polycarbonate resin as a flame retardant.

Another object of the present invention is to use a combination of a phosphazene compound, a phosphate ester morphide flame retardant and a fluorinated alkane sulfonate salt in a thermoplastic polycarbonate resin as a flame retardant to increase the flame resistance without deterioration in physical properties such as heat resistance and mechanical strength. It is to provide a thermoplastic resin composition exhibiting an effect.

The above and other objects of the present invention can be achieved by the present invention described in detail below.

Summary of the Invention

Flame retardant thermoplastic resin composition of the present invention

(A) 100 parts by weight of thermoplastic polycarbonate base resin;

(B) (B ₁ ) Linear phosphazene represented by the following general formula (I-a) and / or cyclic phosphazene compound represented by the following general formula (I-b) 5 to 90 weight%; And

(In the general formulas (I-a) and (I-b), R represents a substituent optionally selected from alkyl group, aryl group, alkyl substituted aryl group, aralkyl group, alkoxy group, aryloxy group, amino group and hydroxy group. , k is 0 or an integer from 1 to 10)

(B ₂ ) 95 to 10% by weight of phosphate ester morphide flame retardant represented by the following general formula (II);

In the above formula (II), x is 1 or 2, R ₁ is C ₆ -C ₂₀ aryl or alkyl substituted C ₆ -C ₂₀ aryl group, and R ₂ is C ₆ -C ₃₀ aryl or alkyl substituted C _{6 to C 30} aryl group derivatives, n and m each represent a number average degree of polymerization, and the average value of n + m is 0 to 5).

1 to 10 parts by weight of a mixture of;

(C) 0.01-1.0 parts by weight of perfluorinated alkane sulfonate salts; And

(D) 0.05 to 5 parts by weight of a fluorinated polyolefin resin having an average particle size of 0.05 to 1000 µm and a density of 1.2 to 2.3 g / cm ³ ;

It is characterized by consisting of.

Or less, the flame-retardant in the respective components of the thermoplastic resin composition (A) polycarbonate-based resin of the present invention, (B) (B ₁₎ a phosphazene compound and (B ₂₎ a mixture of a phosphoric acid ester-based flame retardant, (C) perfluorinated alkane sulfonic Nate salt and (D) fluorinated polyolefin resin are demonstrated in detail.

Detailed Description of the Invention

(A) polycarbonate resin

The aromatic polycarbonate resin, which is the component (A) used in the preparation of the resin composition of the present invention, may be prepared by reacting diphenols represented by the following general formula (I) with phosgene, halogen formate or diester carbonate:

In the above formula, A represents a single bond, C ₁ -C ₅ alkylene, C ₁ -C ₅ alkylidene, C ₅ -C ₆ cycloalkylidene, -S- or -SO _2- .

Specific examples of the diphenol of the general formula (I) include hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, 2,2-bis- (4-hydroxyphenyl) -propane, 2,4-bis -(4-hydroxyphenyl) -2-methylbutane, 1,1-bis- (4-hydroxyphenyl) -cyclohexane, 2,2-bis- (3-chloro-4-hydroxyphenyl) -propane And 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane. Among them, 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane, 1,1-bis- (4-hydroxy Preferred are hydroxyphenyl) -cyclohexane and the like, and more preferred and the most widely used aromatic polycarbonates are 2,2-bis- (4-hydroxyphenyl) -propane, also called bisphenol-A.

Suitable polycarbonates used in the production of the resin composition of the present invention include those having a weight average molecular weight of 10,000 to 200,000, preferably 15,000 to 80,000.

As the polycarbonate used in the preparation of the resin composition of the present invention, a branched chain may be used, preferably 0.05 to 2 mol% of a tri- or more polyfunctional compound based on the total amount of diphenols used for polymerization, For example, it may be prepared by adding a compound having a trivalent or more phenol group.

Examples of the polycarbonate used in the production of the resin composition of the present invention include homo polycarbonates and copolycarbonates, and may also be used in the form of a blend of copolycarbonates and homo polycarbonates.

In addition, the polycarbonate used in the production of the resin composition of the present invention may be partially or entirely replaced by an aromatic polyester-carbonate resin obtained by polymerization in the presence of an ester precursor, such as a bifunctional carboxylic acid.

(B) flame retardant mixture

(B ₁ ) phosphazene compound

The phosphazene compound used in the present invention is a linear phosphazene represented by the following general formula (I-a) and / or a cyclic phosphazene compound represented by the following general formula (I-b):

In the formulas (I-a) and (I-b), R represents a substituent optionally selected from alkyl groups, aryl groups, alkyl substituted aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, amino groups and hydroxy groups. 0 or an integer from 1 to 10.

(B ₂ ) Phosphate ester morphide flame retardant

The phosphate ester morphide-based flame retardant used in the preparation of the resin composition of the present invention is a phosphate ester morphide-based compound represented by the following general formula (II) or a mixture thereof:

In formula (II), x is 1 or 2, R ₁ is C ₆ -C ₂₀ aryl or alkyl substituted C ₆ -C ₂₀ aryl group, R ₂ is C ₆ -C ₃₀ aryl or alkyl substituted C ₆ ~C ₃₀ aryl group, a derivative thereof, n and m represents an average degree of polymerization can be respectively, the average value of n + m is 5-0. Preferred R ₁ is a phenyl group or a phenyl group substituted with an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, isobutyl, isoamyl, t-amyl, and among these, a phenyl group or methyl More preferred are phenyl groups substituted with ethyl, isopropyl or t-butyl groups. Preferred R ₂ are those derived from resorcinol, hydroquinone or bisphenol-A.

Phosphoric acid ester morpholide compounds, such as the formula (II) according to the present invention, first of all the aromatic alcohol and morpholine having R ₁ group in phosphorus oxychloride (POCl ₃ ) in the presence of a suitable catalyst at a temperature of 50 ~ 200 ℃ The aryl morpholino chlorophosphate can be obtained by reacting the aryl morpholino chlorophosphate and the hydroxy aryl compound having an R ₂ group can be prepared by reacting at a temperature of 70 to 220 ° C. using an appropriate catalyst. At this time, a solution polymerization method or a melt polymerization method can be used as a polymerization method.

As a catalyst that can be used to prepare an oligomeric phosphate ester morphide compound such as Structural Formula (II) according to the present invention, aluminum chloride (AlCl ₃ ), magnesium chloride (MgCl ₂ ) or zinc chloride (ZnCl ₂ ) There are metal chlorides, and the like, and trivalent amines such as triethylamine are preferably added to remove hydrogen chloride (HCl) generated by the reaction.

The phosphate ester morphide compound prepared by the above method is monophosphate ester having both 0 and n values when morpholine is reacted with phosphorus oxychloride (POCl ₃ ) in an excess of aromatic alcohol having R ₁ group and morpholine. Only may be prepared, it is possible to control the amount of the compound having a value of both n and m according to the reaction process. In addition, the produced composite can be used as it is or as a purified compound.

(C) perfluorinated alkanesulfonate salts

The perfluorinated alkane sulfonate salts (C) used in the preparation of the flame retardant thermoplastic resin composition of the present invention include sodium or potassium perfluoride butane sulfonate, sodium or potassium perfluorinated methyl butane sulfonate, sodium or potassium perfluorinated octane sulfonate, Sodium or potassium perfluorinated methane sulfonate, sodium or potassium perfluorinated ethane sulfonate, sodium or potassium perfluorinated propane sulfonate, sodium or potassium perfluorinated hexane sulfonate, sodium or potassium perfluorinated heptane sulfonate, tetraethylammonium perfluorinated Butane sulfonate, tetraethylammonium perfluorinated methyl butane sulfonate, and the like. These may be used independently from each other, and two or more different types may be used together. The perfluorinated alkane sulfonate salts are used in an amount of 0.01 to 1.0 parts by weight based on 100 parts by weight of the base resin (A).

(D) fluorinated polyolefin resin

The fluorinated polyolefin resin (D) used in the production of the flame retardant thermoplastic resin composition of the present invention is conventionally available resins such as polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / vinylidene fluoride copolymer , Tetrafluoroethylene / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, and the like. These may be used independently from each other, and two or more different types may be used together.

When the fluorinated polyolefin resin is mixed and extruded together with the other component resins of the present invention, a fibrillar network is formed in the resin to lower the flow viscosity of the resin during combustion and increase the shrinkage rate to increase the shrinkage. To prevent.

The fluorinated resin used in the preparation of the resin composition of the present invention can be prepared using a known polymerization method, for example, a pressure of 7 to 71 kg / ㎠ and a temperature of 0 to 200 ℃, preferably 20 to 100 It can be prepared in an aqueous medium containing free radical forming catalysts such as sodium, potassium or ammonium peroxydisulfate at conditions of < RTI ID = 0.0 >

The fluorinated polyolefin resin may be used in an emulsion state or a powder state. When the fluorinated polyolefin resin in the emulsion state is used, the dispersibility in the entire resin composition is good, but there is a disadvantage in that the manufacturing process is complicated. Therefore, even if it is powder state, if it can disperse | distribute suitably in the whole resin composition and can form a fibrous network, it is preferable to use in powder state.

Fluorinated polyolefin-based resins which can be preferably used in the preparation of the resin composition of the present invention include polytetrafluoroethylene having a particle size of 0.05 to 1,000 µm and specific gravity of 1.2 to 2.3 g / cm 3.

The content of the fluorinated polyolefin resin used in the production of the resin composition of the present invention is 0.05 to 5 parts by weight based on 100 parts by weight of the component (A).

The flame retardant thermoplastic resin composition of the present invention may include general additives such as flame retardant aids, lubricants, mold release agents, nucleating agents, antistatic agents, stabilizers, reinforcing agents, inorganic additive pigments or dyes according to the respective applications in addition to the above components. The inorganic additive to be used may be used in the range of 0 to 60 parts by weight, preferably 1 to 40 parts by weight, based on 100 parts by weight of component (A).

The resin composition of the present invention can be produced by a known method for producing a resin composition. For example, the components of the present invention and other additives may be mixed simultaneously, then melt extruded in an extruder and made into pellets.

The composition of the present invention can be used for molding a variety of products, and is particularly suitable for the manufacture of housings and interiors of computer or electrical and electronic products that require flame retardancy and high impact resistance while being injected at high temperatures.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

Each component used to prepare the resin composition of the present invention is as follows.

(A) polycarbonate resin

A polycarbonate of bisphenol-A having a weight average molecular weight (Mw) of 25,000 was used.

(B) flame retardant mixture

(B ₁ ) phosphazene compound

The phosphazene compound used in the examples of the present invention is a cyclic phosphazene represented by the structure of (I-b), in which R is a phenoxy group and k is a mixture of 1 and 2.

(B ₂ ) Phosphate ester flame retardant

(B _2.1 ) The phosphate ester morphide compound (B _2.1 ) used in the examples of the present invention was obtained by reacting phenol and morpholine with phosphorus oxychloride, which contains 9% by weight of triphenylphosphate. In the general formula (II), 86% by weight of a compound in which R ₁ is a phenyl group, x is 1, and both n and m are 0, R ₁ is a phenyl group, x is 2, and both n and m are 0. A mixture of mono phosphate ester morpholide compounds containing 5% by weight phosphorus compound.

(B _2.2 ) The oligomeric phosphate ester morphide compound (B _2.2 ) used in the examples of the present invention reacts with resorcinol and phenyl morpholino chlorophosphate, where R ₁ is a phenyl group. And R ₂ is a resorcinol derivative, wherein 1.5% by weight of a phosphate ester morpholide compound having n and m of 0 and x of 1, x is 1, and n + m has a value of 1 68.4% by weight and a mixture of oligomeric phosphate ester morpholide compounds containing 30.1% by weight of compounds wherein x is 1 and the value of n + m is 2 or more.

(C) perfluorinated alkanesulfonate salts

The perfluoroalkane sulfonate salts used in the examples of the present invention used FR-2025, a potassium perfluorinated butane sulfonate, commercialized by US 3M.

(D) fluorinated polyolefin resin

Teflon (trade name) 7AJ of Dupont, USA was used.

Examples 1-4 and Comparative Examples A-C

Using the above-mentioned components, the same resin compositions as those shown in Examples 1 to 4 and Comparative Examples A to C of Table 1 were prepared, and their physical properties are also shown in Table 1.

After mixing each component with the composition shown in the said Table 1, antioxidant and a heat stabilizer are added and it mixes in a normal mixer. Then, it fed into the twin screw extruder of L / D = 29 and k = 45 mm. The mixture was prepared into a resin composition in pellet form through an extruder, and a specimen for evaluation of physical properties and flame retardancy at an injection temperature of 300 ° C. was prepared using a 10 oz injection machine.

These specimens were measured for 48 hours at 23 ° C. and 50% relative humidity, and then measured for physical properties according to ASTM standards. The molded specimens were measured for heat deflection temperature according to ASTM D648 and notched Izod impact strength (1/8 ") according to ASTM D256. Flame retardance was evaluated using 0.8 mm thick specimens in accordance with UL-94. The total combustion time is the sum of the first and second combustion times when five specimens were evaluated.

From the results of Table 1 above, when phosphazene compounds and phosphate ester morphide flame retardants are combined with fluorinated alkane sulfonate salts in a polycarbonate base resin, the existing phosphazene compounds and phosphate ester mothers are used. It can be seen that a synergistic effect is exhibited in flame retardancy without deterioration in heat resistance and mechanical strength than in the case of using only a polyd flame retardant.

The flame retardant thermoplastic resin composition according to the present invention exhibits excellent heat resistance and mechanical strength, and is excellent in flame retardancy, and thus is useful for manufacturing an injection molding of a frame, an exterior, or other office equipment of electrical and electronic products.

Example Comparative Example One 2 3 4 A B C (A) polycarbonate resin 100 100 100 100 100 100 100 (B) Organic Phosphorus Compound (B ₁ ) One One One One One One One (B _2.1 ) 4 - 4 4 4 - 5 (B _2.2 ) - 4 - - - 4 - (C) perfluorinated alkanesulfonate salts 0.1 0.1 0.3 1.0 (D) Fluorinated Polyolefin Resin 0.5 0.5 0.5 0.5 0.5 0.5 0.5 UL 94 flame retardant (0.8mm) V-0 V-0 V-0 V-0 V-2 (drip) V-2 (drip) V-0 Total combustion time 17 26 21 26 95 115 45 Heat deflection temperature 100 105 100 100 100 105 95 Izod impact strength (1/8 ") 50 53 52 45 50 52 40

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (6)

(A) 100 parts by weight of thermoplastic polycarbonate base resin; (B) (B ₁ ) Linear phosphazene represented by the following general formula (I-a) and / or cyclic phosphazene compound represented by the following general formula (I-b) 5 to 90 weight%; And (In the general formulas (I-a) and (I-b), R represents a substituent optionally selected from alkyl group, aryl group, alkyl substituted aryl group, aralkyl group, alkoxy group, aryloxy group, amino group and hydroxy group. , k is 0 or an integer from 1 to 10) (B ₂ ) 95 to 10% by weight of phosphate ester morphide flame retardant represented by the following general formula (II); In the above formula (II), x is 1 or 2, R ₁ is C ₆ -C ₂₀ aryl or alkyl substituted C ₆ -C ₂₀ aryl group, and R ₂ is C ₆ -C ₃₀ aryl or alkyl substituted C _{6 to C 30} aryl group derivatives, n and m each represent a number average degree of polymerization, and the average value of n + m is 0 to 5). 1 to 10 parts by weight of a mixture of; (C) 0.01-1.0 parts by weight of perfluorinated alkane sulfonate salts; And (D) 0.05 to 5 parts by weight of a fluorinated polyolefin resin having an average particle size of 0.05 to 1000 µm and a density of 1.2 to 2.3 g / cm 3; Flame-retardant thermoplastic resin composition, characterized in that consisting of. The flame retardant thermoplastic resin composition according to claim 1, wherein the component (B ₁ ) is a phenoxy phosphazene compound. The compound of claim 1, wherein R ₁ of the compound represented by the formula (II) is a phenyl group; Or a phenyl group substituted with an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, isobutyl, isoamyl, t-amyl, and the like. The flame retardant thermoplastic resin composition according to claim 1, wherein R ₂ of the compound represented by formula (II) is a resorcinol, hydroquinone or bisphenol-A derivative. The method of claim 1, wherein the component (C) perfluorinated alkane sulfonate salts are sodium or potassium perfluorinated butane sulfonate, sodium or potassium perfluorinated methylbutane sulfonate, sodium or potassium perfluorinated octane sulfonate, sodium or potassium Methane perfluorinated sulfonate, sodium or potassium perfluorinated sulfonate, sodium or potassium perfluorinated propane sulfonate, sodium or potassium perfluorinated sulfonate, sodium or potassium perfluorinated heptane sulfonate, tetraethylammonium perfluorinated butane sulfonate And tetraethylammonium perfluorinated methyl butane sulfonate. The flame retardant thermoplastic resin composition characterized by the above-mentioned. The flame retardant thermoplastic resin composition according to claim 5, wherein the perfluorinated alkane sulfonate salt is potassium perfluorinated butane sulfonate.