JPH11209600A - Polyphenylene ether flame-retardant resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame-retardant resin composition that can inhibit the combustion dripping, shows excellent molding fluidity and is useful as parts for household electric appliances by compounding polyphenylene ether resin, a phosphorus flame retarder and a specific poly(tetrafluoroethylene) resin in a specific proportion. SOLUTION: This flame-retardant resin composition comprises (A) 100 pts.wt. of a poly(phenylene ether) resin such as poly(2,6-dimethyl-1,4-phenylene) ether, (B) 1-30 pts.wt. of a phosphorus flame retarder as phosphoric ester and (C) 0.02-1 pt.wt. of PTFE that has a number-average molecular weight Mn of <=1,000,000 calculated according to formula I (Mn is the number-average molecular weight; ΔHc is the non-dimensional value of the crystal heating in the unit of cal/g, when DSC is measured at the temperature descending rate of 10CC/min and has the crystallinity of >=96% calculated from formula II [TC is the crystallinity in %; AT = (the absorbance at 778 cm<-1> wavelength)/(the absorbance at 2367 cm<-1> wave length); the absorbance is the value obtained by IR measurement].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyphenylene ether-based flame-retardant resin composition excellent in drip prevention performance during combustion.

[0002]

2. Description of the Related Art Polyphenylene ether resins have properties such as excellent mechanical properties, electrical properties, acid resistance, alkali resistance, and heat resistance, as well as low water absorption and good dimensional stability. Although they are widely used as materials for housings and chassis of OA equipment such as computers and word processors, these materials are often required to have high flame retardancy due to safety problems.

[0003] For the purpose of improving the flame retardancy of a polyphenylene ether-based resin, it has been conventionally known that a phosphate compound such as triphenyl phosphate or cresyl diphenyl phosphate is blended as a flame retardant. Furthermore, the above-mentioned drawbacks when the phosphate ester compound is blended, a decrease in heat resistance, volatilization of the phosphate ester compound during molding,
For the purpose of improving bleed and the like, resorcinol / bisphenyl phosphate compounds, bisphenol A-polyphenyl phosphate compounds, etc., which are condensed phosphate compounds having a large molecular weight, have been used.

[0004] Furthermore, in recent years, the demand for fire safety has been particularly noticed, and regulations on the UL (Underwriters Laboratory) vertical combustion test for home electric appliances, OA equipment, and the like have become stricter with the years. In addition, as the thickness of products and parts has become thinner in order to reduce weight and improve economical efficiency, fires will drip during combustion, causing damage to other products and parts. There is a strong demand for the development of a technique for preventing a fire from dropping, a so-called dripping prevention technique. As dripping prevention technology,
Although a method of increasing the amount of a flame retardant is known, it is not economical to use a large amount of an originally expensive flame retardant, and it is preferable to promote generation of toxic gas and deterioration of mechanical properties. Absent.

As a conventional technique for preventing the dropping of a polyphenylene ether resin, US Pat. No. 4,355,126 discloses a technique in which polyphenylene ether, a vinyl aromatic resin, a flame retardant, and polytetrafluoroethylene (PTFE) are blended. Further, U.S. Pat. No. 4,716,196 discloses a polystyrene resin containing polyphenylene ether, a flame retardant, and PTFE having a particle size in the range of 70 to 700 microns.
Is disclosed. However, although all of the techniques attempt to develop the anti-dripping performance by adding PTFE, there is no description about the crystallinity and molecular weight of crystalline PTFE. Further, even if PTFE is added as an anti-dripping agent for the polyphenylene ether-based resin, the
Depending on the type of E, there are problems that sufficient anti-dripping performance is not exhibited, that the appearance is reduced, and that the flowability is reduced by increasing the amount of PTFE added.

[0006]

SUMMARY OF THE INVENTION In view of such circumstances, the present inventors have developed a method of preventing dripping during combustion of a polyphenylene ether-based resin, with a small amount of PTFE exhibiting sufficient dripping preventing performance, The present inventors have studied the development of a material having excellent fluidity. As a result, they have found that the incorporation of PTFE having a specific molecular weight and a specific crystallinity solves the above-mentioned problems, and has reached the present invention.

[0007]

That is, the polyphenylene ether-based resin composition of the present invention comprises (A) 1 to 30 parts by weight of a phosphorus-based flame retardant and (C) based on 100 parts by weight of a polyphenylene ether-based resin. ) 0.02 to 1 part by weight of polytetrafluoroethylene (PTFE) having a number average molecular weight (Mn) determined by the formula (1) of 1,000,000 or more and a degree of crystallinity determined by the formula (2) of 96% or more. And a flame-retardant resin composition.

Formula (1) Mn = 2.1 × 10 ¹⁰ ΔHc ~ ^5.16 (wherein Mn is a number average molecular weight, ΔHc is a temperature decreasing rate of 10 ° C.)
/ Min. The value obtained by making the crystal heating in cal / g units when the DSC measurement was performed as a dimensionless amount. ) Formula (2) C = (1−0.25 × AI) × 100 (where C is the crystallinity (%), AI = (absorbance at 778 cm− ¹ ) / (absorbance at 2367 cm− ¹ ). Is IR
(Value Obtained by Measurement) In the present invention, the (A) polyphenylene ether-based resin is a polyphenylene ether alone or a mixture with a styrene-based resin.

The polyphenylene ether is a homopolymer or a copolymer having the following general formula (1) as a repeating unit.

[0010]

Embedded image

(Wherein R1, R2, R3 and R4 are carbon 1
To 4 alkyl groups, aryl groups, monovalent residues such as hydrogen, and R3 and R4 are not simultaneously hydrogen. Representative examples of the homopolymer of polyphenylene ether include poly (2,6-dimethyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ether and poly (2 , 6-Diethyl-1,4-
Phenylene) ether, poly (2,6-diphenyl-)
1,4-phenylene) ether, poly (2,3,6-trimethyl-1,4-phenylene) ether and the like. Among them, particularly preferred is poly (2,6-dimethyl-1,4-phenylene) ether.

Examples of the polyphenylene ether copolymer include 2,6-dimethylphenol and 2,3,3-dimethylphenol.
Copolymer with 6-trimethylphenol or 2,6
A copolymer with diphenylphenol or a copolymer with o-cresol.

[0013] Further, those obtained by adding an amine compound or the like to the terminal or main chain by the polymerization method of polyphenylene ether and those obtained by modifying the terminal with a vinyl compound such as styrene or acrylate compound are included.

The styrene resin used in the present invention is:
Homopolymers or copolymers of styrene compounds, and rubber-modified polymers thereof.

Examples of the styrene-based compound include, in addition to styrene, nuclear alkyl-substituted styrenes such as o-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4-dimethylstyrene, and ethylstyrene; α-methylstyrene; α-alkyl-substituted styrenes such as α-methyl-p-methylstyrene and the like. Further, as the compound copolymerizable with the styrene-based compound, methyl methacrylate, methacrylates such as ethyl methacrylate, acrylonitrile, unsaturated nitrile compounds such as methacrylonitrile, acid anhydrides such as maleic anhydride,
Diene compounds having a conjugated double bond such as butadiene and isoprene, and hydrogenated products thereof are also included.
Among these polymers, particularly preferred polymers are polystyrene, styrene-acrylonitrile copolymer, rubber-modified polystyrene, and rubber-modified styrene-acrylonitrile copolymer.

The mixing ratio of the polyphenylene ether-based resin to the polystyrene-based resin is not limited. Polyphenylene ether may be used alone, but mixing with a styrene-based resin is preferred in view of fluidity. The preferred mixing ratio is polyphenylene ether 2
It is in the range of 0 to 90 parts by weight and 10 to 80 parts by weight of the styrene resin.

The (B) phosphorus-based flame retardant used in the present invention includes:
Any phosphorus-containing flame retardant known in the art, such as organic phosphorus compounds, red phosphorus, and inorganic phosphates can be used. Among them, a phosphate compound is preferably used. For example, the following general formulas (2) and (3):

[0018]

Embedded image

[0019]

Embedded image

Wherein R1, R2, R3, R4, R5,
R6 and R7 are each independently a phenyl group or an aryl group substituted with 1 to 3 alkyl groups having 1 to 6 carbon atoms, and may be an aromatic ring group further substituted with a hydroxyl group. X is an arylene group, n is a natural number, j,
k, l, and m are each independently 0 or 1. ), And among them, the condensed phosphate compound represented by the general formula (2) is more preferable.

Particularly preferred phosphate compound is a compound represented by the following general formula (4).

[0022]

Embedded image

(Wherein Q1, Q2, Q3, and Q4 represent an alkyl group having 1 to 6 carbon atoms or hydrogen;
2, R3 and R4 represent a methyl group or hydrogen. n is 1
N1 and n2 represent integers from 0 to 2;
1, m2, m3, and m4 each represent an integer of 1 to 3. The amount of the phosphorus-based flame retardant is in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyphenylene ether-based resin.
Preferably it is in the range of 5 to 20 parts by weight.

The present invention is characterized by polytetrafluoroethylene (PTFE) used as (C). Production of PTFE is performed by an emulsion polymerization method or a suspension polymerization method by radical polymerization using a peroxide using a tetrafluoroethylene monomer as a raw material. Further, a modified type in which a part of the fluorine atom is replaced with another substituent or element is also used. PTF obtained by this method
E takes the form of a powder or dispersion,
It is highly crystalline and readily fibrillates. In trying to blend the PTFE thus obtained with the resin composition of the present invention, it is extremely important that two values of the molecular weight and the crystallinity of the PTFE are at least certain values. That is, as the molecular weight, the number average molecular weight determined by the formula (1) is 1,000,000 or more, preferably 2,000,000 or more. Further, as the crystallinity, the value obtained by the above equation (2) is:
By blending PTFE of 96% or more, preferably 97% or more, a small amount can exhibit sufficient dripping prevention performance, and a composition excellent in appearance and fluidity can be obtained. PTFE having a crystallinity of less than 96% even if the number average molecular weight is 1,000,000 or more
In this case, not only does the appearance of the molded product deteriorate, but also the drip prevention performance is not sufficient. Further, PTFE having a molecular weight of less than 1,000,000 even when the crystallinity is 96% or more does not exhibit sufficient dripping prevention performance.

The equation (1) used for quantifying the number average molecular weight is expressed by 3256 in Journal of Applied Polymer Science, Vol. 17, Section 3253 (1973).
The relational expression between the heat of crystallization and the number average molecular weight in the DSC measurement described in the section is used.

The equation (2) used for quantifying the degree of crystallinity is represented by the following equation (3) at the time of IR measurement, described in Fluoropolymer Handbook, 42-45, published by Nikkan Kogyo Shimbun. The relationship between the absorbance ratio (AI) and the crystallinity expressed by

Formula (3) AI = (absorbance at 778 cm- ¹ ) / (absorbance at 2367 cm- ¹ ) The blending amount of PTFE is as follows.
It is in the range of 0.02 to 1 part by weight based on 00 parts by weight.
Preferably, the amount is 0.05 to 0.5 part by weight. However, if the PTFE of the present invention is used, a small amount of about 0.02 part can exhibit a certain degree of dripping prevention performance. Rather, it is not economical to add more than necessary, and it deteriorates the fluidity and the appearance of the molded article. A particularly preferred addition amount is 0.05 to 0.3 parts by weight.

The method for producing the flame-retardant resin composition of the present invention can be produced by melt-kneading using a generally known kneader such as an extruder, a heating roll, a kneader or a Banbury mixer. Particularly preferred is production by an extruder.

As PTFE, both powder and dispersion are used within the scope of the present invention. Examples thereof include a method of dry-blending with a polyphenylene ether-based resin to be kneaded and supplying the same to an extruder, and a method of adding a dispersion from a supply port provided in the middle of the extruder.
It is also conceivable to add PTFE after preparing a master batch with a polyphenylene ether-based resin or another resin.

The temperature at which the melt-kneading is performed is not particularly limited as long as the polyphenylene ether-based resin to be kneaded is melted, but the kneading is preferably performed at a temperature in the range of 240 ° C. to 300 ° C.

The flame-retardant resin composition of the present invention may contain other flame retardants and anti-dripping agents, for example, halogen-based flame retardants such as decabromodiphenyl ether, tetrabromobisphenol A, hexabromobenzene, and ammonium bromide. Halogen-containing inorganic compounds, red phosphorus, polyphosphoric acid,
Organic or inorganic phosphorus compounds such as ammonium phosphate; nitrogen-containing phosphorus compounds such as phosphonoamides; triazine skeleton-containing compounds such as melamines; inorganic compounds such as antimony oxide; metal hydroxides; phenolic resins; , Glass fiber, carbon fiber or the like may be used in combination.

The flame-retardant resin composition of the present invention may optionally contain a thermoplastic elastomer to improve impact resistance. For example, a styrene-butadiene block copolymer and a styrene-butadiene block copolymer in which part or all of butadiene is hydrogenated are exemplified.

Further, in order to impart other properties, other additives such as a plasticizer, for example, a plasticizer or the like may be used within a range not to impair the effects of the present invention.
A release agent, an antistatic agent, an ultraviolet absorber, an antioxidant, a light stabilizer, a colorant, an inorganic filler and the like can be contained.

[0034]

Next, the present invention will be described specifically with reference to examples. The following examples are all illustrative and do not limit the content of the present invention.

The raw materials used in the examples and comparative examples are as follows.

(A) Polyphenylene ether-based resin A-1: Poly (2,6-dimethyl-1,4-phenylene-ether) having a reduced viscosity of 0.54 (at 30 ° C. in chloroform) A-2: Rubber-modified Polystyrene (made by Asahi Kasei Corporation)
Trade name, Asahi Kasei polystyrene 494).

A-3: Polystyrene (Asahi Kasei Corporation)
Manufactured by Asahi Kasei Polystyrene 685).

(B) Phosphorus-based flame retardant B-1: Bisphenol A-polyphenyl phosphate (manufactured by Daihachi Chemical Co., Ltd., CR-741) B-2: Triphenyl phosphate (manufactured by Daihachi Chemical Co., Ltd., TPP) (C) Polytetrafluoroethylene The polytetrafluoroethylene shown in Table 1 was used. The DSC measurement for calculating the number average molecular weight and the IR measurement for calculating the crystallinity are performed by the following methods.

DSC measurement: Using DSC7 manufactured by PERKIN-ELMER, about 10 mg of a PTFE sample was accurately measured (in units of 0.1 mg), and 10 ° C./m from room temperature.
in. Immediately after heating up to 400 ° C at a speed of 10 ° C / mi
n. The temperature was lowered to 100 ° C. at the speed shown in FIG. 310 ° C when the temperature drops
The peak observed in the vicinity was processed by the onset method, and the heat of crystallization (in cal / g) was determined from the peak area and the sample amount.

IR measurement: A PTFE sample was formed into a film by compression molding at normal temperature, and FT / IR-70 manufactured by JASCO Corporation.
Using 00, IR measurement was performed in the range of 4000 cm- ¹ to 400 cm- ¹ . 778cm ~ ¹ from absorption spectrum
And the absorbance at 2367 cm- ¹ .

[0041]

[Table 1]

The combustion test and the evaluation of the physical properties were performed according to the following methods and conditions.

(1) Flame Retardancy Test A vertical combustion test and a 5V (vertical) test were performed on a test piece having a thickness of 1/16 inch based on the method specified in the UL-94 standard.

(2) Molding fluidity When a dumbbell piece for a tensile test having a thickness of 3.2 mm and a length of 217 mm in the flowing direction was injection molded, the minimum molding pressure (hereinafter referred to as SSP) required to completely fill the molded piece. Abbreviated.)
Was measured and used as a measure of molding fluidity. The lower the SSP value, the better the molding fluidity.

(3) Heat deformation temperature Load of 18.6 kg / cm ² based on ASTM D648
Was measured.

(4) Surface Condition of Molded Piece The injection molded piece was judged visually and tactilely. A surface having a smooth surface was evaluated as good, and a rough surface was evaluated as poor.

Examples 1 to 7 and Comparative Examples 1 to 4 According to the composition shown in Tables 2 and 3, the mixture was fed to a 30 mm twin-screw extruder set at a cylinder temperature of 300 ° C. and melt-kneaded at 100 rpm. The mixture was cut by cooling to obtain pellets. The pellets are heated at a cylinder temperature of 2
A test piece was obtained by molding at a mold temperature of 60 ° C. by an injection molding machine set at 40 ° C. Using this test piece, a combustion test and evaluation of physical properties were performed, and the results are shown in Tables 2 and 3.

Looking at the results in Table 2, it can be seen that the PTF within the scope of the present invention was obtained.
In all of Examples 1 to 4 using E, the number of drops was 0 or 1 out of 5 in the UL-94 vertical combustion test.
On the other hand, in Comparative Example 1 in which the number average molecular weight falls within the range of the present invention but the crystallinity does not enter, all five of the five samples were dropped. Further, although the degree of crystallinity falls within the range of the present invention, all five of Comparative Examples 2 in which the number average molecular weight does not fall were dropped.

From the results shown in Table 3, it can be seen that when the added amount of PTFE is 0.02 parts by weight or more, it is effective in preventing dripping during the combustion test. When the addition amount is 2 parts, not only the molding fluidity deteriorates, but also the surface condition of the molded piece deteriorates, which is not a preferable example.

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

Industrial Applicability The resin composition of the present invention is a flame-retardant resin composition which is excellent in drip prevention during combustion, and is excellent in the appearance of molded articles and molding fluidity. This composition is suitable for home electric parts, OA equipment parts, and the like, and plays a large role in these industries.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 27:18)

Claims (1)

[Claims] (A) Polyphenylene ether-based resin 1
(C) 1 to 30 parts by weight of the phosphorus-based flame retardant and (C) crystallization whose number average molecular weight (Mn) determined by the formula (1) is 1,000,000 or more and the formula (2) A flame-retardant resin composition comprising 0.02 to 1 part by weight of polytetrafluoroethylene (PTFE) having a degree of 96% or more. Formula (1) Mn = 2.1 × 10 ¹⁰ ΔHc ~ ^5.16 (wherein Mn is a number average molecular weight, ΔHc is a cooling rate of 10 ° C.)
/ Min. The value obtained by making the crystal heating in cal / g units when the DSC measurement was performed as a dimensionless amount. ) Formula (2) C = (1−0.25 × AI) × 100 (where C is the crystallinity (%), AI = (absorbance at 778 cm− ¹ ) / (absorbance at 2367 cm− ¹ ). Is IR
Value obtained by measurement)