JPH11181267A - Fire retardant polycarbonate resin composition and light reflecting plate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fire retardant polycarbonate resin composition, improving a high reflectivity, light shielding property, heat-aging resistance, dust adhesion resistance, etc., without damaging a fire retardant property and mechanical physical properties, and to provide a light reflecting plate obtained by forming the same composition. SOLUTION: This fire retardant polycarbonate resin composition contains (A) polycarbonate resin and (B) titanium oxide powder in a weight ratio of (A) to (B) of (70:30)-(90:10), and is blended with (C) 1-8 pt.wt. alkylbenzene sulfonic acid based static resistant agent, (D) 100-3,000 ppm wt. phosphorus-based antioxidant and (E) 0.01-5 pt.wt. organopolysiloxane containing alkoxy group based on (100 pts.wt.) total weight of the components (A) and (B), and also a light reflecting plate is produced by forming the above composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant polycarbonate resin composition and a light-reflecting plate using the same.
More specifically, a flame-retardant polycarbonate containing no bromine compound that has improved high reflectivity, light-shielding properties, heat aging resistance, dust adhesion, etc. without impairing mechanical properties such as flame retardancy and impact resistance The present invention relates to a resin composition and a light-reflecting plate suitable for use in a backlight of a liquid crystal display formed by molding the composition.

[0002]

2. Description of the Related Art Polycarbonate resins are excellent as mechanical plastics (particularly, impact resistance), electrical characteristics, transparency, etc.
It is widely used in various fields such as A-devices, electric / electronic devices, and construction. Among these fields of use, high reflectance is required especially for the use of a reflector for a liquid crystal display backlight.

[0003] This polycarbonate resin has a high oxygen index among various thermoplastic resins and generally has self-extinguishing properties. However, in the field of OA equipment, electric and electronic equipment,
In order to satisfy safety requirements in various other applications,
Further, there is a strong demand for a resin composition having enhanced flame retardancy. On the other hand, in recent years, non-bromo (bromine-free) flame retardants have been required due to environmental issues. In addition, in the use of a reflector for a liquid crystal display backlight, high light-shielding properties and light resistance as well as the high reflectance described above are required. Has been requested.
Further, as the thickness of products using liquid crystal displays such as televisions and personal computers (PCs) is reduced, materials having excellent moldability are required. In addition, as liquid crystal panels have been improved to have higher definition and higher brightness, a problem has arisen in that dust adhering to the backlight reflector appears on the display screen.

[0004] From these backgrounds, while maintaining mechanical properties such as flame retardancy and impact resistance, high reflectivity, light shielding property,
There is a need for a flame-retardant polycarbonate resin composition that does not contain a bromine compound and that has excellent heat aging resistance and that does not cause dust adhesion. As a material for improving the reflectance of polycarbonate resin, a material obtained by blending titanium oxide with polycarbonate resin is known (Japanese Patent Publication No. Sho 6
No. 3-26140). However, a material containing conventional titanium oxide has low light-shielding properties, causes a problem of transparency, inevitably causes a decrease in luminance, is inferior in dust adhesion resistance, and inferior in heat aging resistance. Had disadvantages.

[0005]

SUMMARY OF THE INVENTION The present invention provides a high reflectivity, light-shielding property, heat aging resistance and dust resistance under such circumstances without impairing mechanical properties such as flame retardancy and impact resistance. An object of the present invention is to provide a non-brominated flame-retardant polycarbonate resin composition having improved adhesion and the like, and a flame-retardant light-reflecting plate using the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a polycarbonate resin containing a relatively large amount of titanium oxide has been added to a specific antistatic agent and phosphorous. Polycarbonate resin composition containing a predetermined antioxidant, a specific organopolysiloxane, and optionally a halogen-free phosphate compound, tetrafluoroethylene, a light diffusing agent, and a stilbenebisbenzoxazole derivative, respectively. And a light reflector obtained by molding the resin composition can be adapted to the purpose. The present invention has been completed based on such findings.

That is, the present invention relates to (1) a composition comprising (A) a polycarbonate resin and (B) a titanium oxide powder in a weight ratio of 70:30 to 90:10, and ) Total weight with the component (1
(C) 1 to 8 parts by weight of an alkylbenzenesulfonic acid-based antistatic agent (D) 100 to 3000 ppm by weight of a phosphorus-based antioxidant and (E) 0.01 to 5 parts by weight of an alkoxy group-containing organopolysiloxane. A flame-retardant polycarbonate resin composition containing parts by weight. (2) The description of (1), further comprising (F) 0.05 to 1 part by weight of a halogen-free phosphate ester compound as a phosphorus element based on 100 parts by weight of the total of the components (A) and (B). Flame-retardant polycarbonate resin composition. (3) Based on a total of 100 parts by weight of the components (A) and (B), (G) 0.01 to 1 part by weight of polytetrafluoroethylene having a fibril-forming ability is further blended (1) or (1). The flame-retardant polycarbonate resin composition according to 2). (4) The composition according to any one of (1) to (3), further comprising (H) 0.05 to 5 parts by weight of a light diffusing agent based on 100 parts by weight of the total of the components (A) and (B). The flame-retardant polycarbonate resin composition as described in the above. (5) Based on the total weight of the components (A) and (B), (I) the stilbenebisbenzoxazole derivative 1
The flame-retardant polycarbonate resin composition according to any one of (1) to (4), wherein the composition contains from 1 to 1000 ppm by weight. (6) A light reflecting plate formed by molding the flame-retardant polycarbonate resin composition according to any one of (1) to (5). (7) A light reflector according to (6), which is a reflector for a liquid crystal display backlight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the flame-retardant polycarbonate resin composition of the present invention, as the polycarbonate resin used as the component (A), various ones can be mentioned. I)

[0009]

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A polymer having a repeating unit having a structure represented by the following formula is preferred. In the above general formula (I), X ¹ and X ² each represent a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and specific examples include a methyl group,
Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-amyl group, isoamyl group, n-hexyl group, isohexyl group,
Examples include a cyclopentyl group and a cyclohexyl group. X ¹ and X ² may be the same or different. a and b represent the number of substitutions of X ¹ and X ² , respectively, and are integers of 0 to 4. When plural X ^1, a plurality of X ¹ may be the same as or different from each other, if X ² is plural, X ² may be the same with or different from each other.

Y is a single bond, an alkylene group having 1 to 8 carbon atoms (eg, a methylene group, an ethylene group, a propylene group, a butylene group, a pentylylene group, a hexylene group), an alkylidene group having 2 to 8 carbon atoms (eg, an ethylidene group) , Isopropylidene group, etc.), a cycloalkylene group having 5 to 15 carbon atoms (eg, cyclopentylene group, cyclohexylene group, etc.), a cycloalkylidene group having 5 to 15 carbon atoms (eg, cyclopentylidene group, cyclohexylidene group, etc.) ), - S -, - SO -, - SO 2 -, - O -, - CO
A bond or a formula (II-1) or a formula (II-2)

[0012]

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[0013] The bond represented by The polymer is usually represented by the general formula (III)

[0014]

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(Where X ¹ , X ² , a, b and Y are
It is the same as the above definition. ), And a carbonate precursor such as phosgene or a carbonate compound. That is, for example, in a solvent such as methylene chloride, in the presence of a known acid acceptor or molecular weight regulator, by the reaction of a dihydric phenol with a carbonate precursor such as phosgene, or in the presence or absence of a solvent, It can be produced by a transesterification reaction between a polyhydric phenol and a carbonate precursor such as a carbonate compound.

As the dihydric phenol represented by the general formula (III), various ones can be mentioned.
-Bis (4-hydroxyphenyl) propane [commonly known as bisphenol A] is preferred. Examples of the dihydric phenol other than bisphenol A include bis (4-hydroxyphenyl) methane; 1,1-bis (4-hydroxyphenyl) ethane; and bis (4 such as 1,2-bis (4-hydroxyphenyl) ethane. -Hydroxyphenyl) alkane, 1,1-bis (4-hydroxyphenyl) cyclohexane; bis (4-hydroxyphenyl) cycloalkane such as 1,1-bis (4-hydroxyphenyl) cyclodecane, 4,4′-dihydroxydiphenyl , Bis (4-hydroxyphenyl) oxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ether Hydroxyphenyl) ketone and the like It is. In addition, examples of the dihydric phenol include hydroquinone. These dihydric phenols may be used alone or in combination of two or more.

Examples of the carbonic acid ester include diaryl carbonates such as diphenyl carbonate, and dialkyl carbonates such as dimethyl carbonate and diethyl carbonate. When reacting the dihydric phenol with the carbonate precursor to produce a polycarbonate, a molecular weight modifier can be used as necessary. The molecular weight regulator is not particularly limited, and those conventionally used in the production of polycarbonate can be used. Such materials include, for example, phenol, p-cresol, p-tert-butylphenol, p-tert-octylphenol, p-
Monohydric phenols such as cumylphenol and nonylphenol are exemplified.

The polycarbonate resin of the component (A) may be a homopolymer using one of the above-mentioned dihydric phenols, or a copolymer using two or more of the above-mentioned dihydric phenols. Further, it may be a thermoplastic random branched polycarbonate resin obtained by using a polyfunctional aromatic compound in combination with the above-mentioned monohydric phenol. Further, a polycarbonate-polyorganosiloxane copolymer comprising an organosiloxane block having a number average degree of polymerization of 5 or more may be used.

Further, a mixture of two or more kinds of various polycarbonate resins may be used. In the composition of the present invention, the polycarbonate resin used as the component (A) has a viscosity average molecular weight of 13,000 to 30 in view of mechanical strength, particularly, Izod impact strength and moldability.
000, especially 15,000 to 25,000
Are preferred.

Polycarbonate resins having such characteristics include, for example, Teflon FN3000A and FN2500.
A, FN2200A, FN1900A, FN1500A
It is commercially available as an aromatic polycarbonate resin (trade name, manufactured by Idemitsu Petrochemical Co., Ltd.). In the resin composition of the present invention, the titanium oxide powder used as the component (B) is essentially low reflective (highly transparent) (A)
It has the effect of reducing the transparency and increasing the whiteness of the polycarbonate resin as a component, imparting high reflectivity, and improving the flame retardancy of the polycarbonate resin.

The composition obtained by adding titanium oxide as a white pigment to a polycarbonate resin has already been disclosed in JP-B-63-1988.
No. 26140, JP-A-6-200140, U.S. Pat. No. 5,391,1600, and the like, but there is no mention of a specific use of a reflection plate or the like using the composition. As described above, titanium oxide as the component (B) is used in the form of a fine powder for the purpose of imparting low transparency and high reflectivity to the polycarbonate resin of the component (A). Titanium can be produced by either the chlorine method or the sulfuric acid method.

The titanium oxide used in the present invention is:
Any of a rutile type and an anatase type may be used, but a rutile type is preferable in terms of thermal stability, weather resistance and the like. Further, the shape of the fine powder particles is not particularly limited, and can be appropriately selected and used, such as flaky, spherical, amorphous and the like. The titanium oxide used as the component (B) includes aluminum and / or
Alternatively, those which are surface-treated with an amine compound, a polyol compound or the like in addition to a silicon hydrated oxide are preferable. This treatment improves the uniform dispersibility in the polycarbonate resin composition and the stability of the dispersed state, and further improves the affinity with the flame retardant of the component (D) described later to form a uniform composition. Preferred for production.

Examples of the hydrated oxides, amine compounds and polyol compounds of aluminum and silicon include hydrated alumina, hydrated silica, triethanolamine and trimethylolethane, respectively. The treatment method itself in the surface treatment is not particularly limited, and an arbitrary method is appropriately adopted. The amount of the surface treatment agent imparted to the surface of the titanium oxide particles by this treatment is not particularly limited, but the light reflectivity of the titanium oxide and 1 to 1 with respect to the titanium oxide in consideration of the moldability of the polycarbonate resin composition. About 15% by weight is appropriate.

In the composition of the present invention, the particle diameter of the titanium oxide powder used as the component (B) is not particularly limited. However, in order to exhibit the above-mentioned effects efficiently, the average particle diameter is 0.1 to 0. Those having a size of about 0.5 μm are preferable. The content ratio of the polycarbonate resin of the component (A) and the titanium oxide powder of the component (B) in the composition of the present invention is selected in a weight ratio of 70:30 to 90:10. If the amount of the titanium oxide powder is less than the above range, the light-shielding properties are insufficient, and the effect of improving the flame retardancy is not sufficiently exhibited, and if the amount is more than the above range, the moldability deteriorates and silver is generated on the molded product. Tend to increase. The content ratio of the component (A) and the component (B) is particularly preferably in the range of 70:30 to 85:15 in terms of light-shielding properties, flame retardancy, moldability, and the like.

In the composition of the present invention, the alkylbenzenesulfonic acid-based antistatic agent used as the component (C) includes alkali metal salts of alkylbenzenesulfonic acid (such as sodium salt, potassium salt and lithium salt) and phosphonium salt of alkylbenzenesulfonic acid. In the present invention, phosphonium dodecylbenzenesulfonate is preferred because it does not cause a decrease in flame retardancy and high reflectivity.
In this case, it is possible to use together with an alkali metal salt of dodecylbenzenesulfonic acid according to the required characteristics of antistatic performance. The amount of addition is 1 to 8 parts by weight, preferably 1 to 4 parts by weight, based on 100 parts by weight of the total of the components (A) and (B). If the amount of the component (C) is less than 1 part by weight, the dust resistance is poor, and 8
Exceeding the weight parts results in poor heat resistance and appearance.

Examples of the component (D) phosphorus antioxidant used in the composition of the present invention include a phosphite compound and an aromatic phosphine compound. As a phosphite compound, pentaeristol-phosphite compound (PEP), ADK STAB PEP-36, P
EP-24 and PEP-8 (both manufactured by Asahi Denka Kogyo KK) are preferred, and PEP-36 is particularly preferred.

Examples of the aromatic phosphine compound include triphenyl phosphine, dicyclohexyl phenyl phosphine, triparatolyl phosphine, tris-4-methoxyphenyl phosphine, trimetatrile phosphine and the like. Among them, triphenylphosphine is particularly preferred. As the addition amount of the phosphorus-based antioxidant, 100 to 3000 wt ppm of the same compounding amount as a normal antioxidant is used.
When the amount is less than 100 ppm by weight, the heat aging resistance is not preferable, and when the amount exceeds 3000 ppm, the reflectance is lowered.

In the composition of the present invention, an alkoxy group is used as the component (E) in order to stabilize the thermoformability, and in particular to improve the properties of the component (B) titanium oxide, which tends to inhibit the smoothness of the surface of the molded article. It is necessary to contain a contained organopolysiloxane (hereinafter referred to as an organopolysiloxane).
There are various types of the organopolysiloxane. Specifically, the organopolysiloxane contains an organooxysilyl group in which an alkoxy group is bonded to a silicon atom directly or via a divalent hydrocarbon group, and may have a linear, cyclic, or cyclic structure. Examples thereof include reticulated and partially branched linear organopolysiloxanes. Particularly, a linear organopolysiloxane is preferable. Examples of the organopolysiloxane containing an organooxysilyl group in which an alkoxy group is bonded to a silicon atom directly or via a divalent hydrocarbon group include, for example, a compound represented by the general formula (IV):

[0029]

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Wherein R ¹ represents a monovalent hydrocarbon group;
Is a monovalent hydrocarbon group, an alkoxy group (—OR ⁴ ) or a general formula (V)

[0031]

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(Wherein R ² represents a divalent hydrocarbon group;
³ and R ⁴ represent a monovalent hydrocarbon group. X is an integer of 0 to 2. ) Represents an organooxysilyl group-containing monovalent hydrocarbon group. However, at least one of A in one molecule is an alkoxy group or an organooxysilyl group-containing monovalent hydrocarbon group. Further, m is an integer of 1 to 300, n is an integer of 0 to 300, and m + n is 1
It is an integer of up to 300. And a linear organopolysiloxane represented by the following formula:

Here, in the general formula (V), specific examples of the monovalent hydrocarbon group represented by R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and a hexyl group. Alkenyl groups such as alkyl group, vinyl group, allyl group, butenyl group, pentenyl group and hexenyl group;
An aryl group such as a phenyl group, a tolyl group and a xylyl group, and an aralkyl group such as a benzyl group and a phenethyl group are exemplified. A specific example of the monovalent hydrocarbon group represented by A is
It is the same as in the case of R ¹ above.

On the other hand, in the general formula (V), examples of the divalent hydrocarbon group represented by R ² include an alkylene group such as a methylene group, an ethylene group, a propylene group and a butylene group. The monovalent hydrocarbon groups represented by R ³ and R ⁴ are the same as those described above, and specific examples of the organooxysilyl group-containing monovalent hydrocarbon group include trimethoxysilylethylene and triethoxysilyl. Examples include an ethylene group, a dimethoxyphenoxysilyl propylene group, a trimethoxysilylpropylene group, a trimethoxysilylbutylene group, a methyldimethoxysilylpropylene group, and a dimethylmethoxysilylpropylene group. The organopolysiloxane of the component (E) may be used singly or in combination of two or more.

In the composition of the present invention, the content of the organopolysiloxane of component (E), which is used as required, is not particularly limited. A range from 0.01 to 5 parts by weight, based on the total weight with the titanium powder, is advantageous. If the amount is less than 0.01 part by weight, the effect of improving the properties of titanium oxide may not be sufficiently exhibited. If the amount exceeds 5 parts by weight, the effect is not so much improved for the amount, and it is more economical. In addition to the disadvantages, there is a tendency that the mechanical properties such as the impact strength of the molded product are reduced. In the composition of the present invention, for the purpose of further improving the flame retardancy, if necessary,
As the component (F), a halogen-free phosphate compound can be contained. The halogen-free phosphoric acid ester compound has a synergistic effect with the titanium oxide powder of the component (B), thereby imparting excellent flame retardancy, and also has an effect of improving the stabilization of the thermoformability of the polycarbonate resin composition. Have. Since the halogen-free phosphate compound of the component (F) does not contain a halogen atom such as bromine, when a molded article containing this is discarded, there is little risk of causing environmental pollution.

As such a halogen-free phosphoric acid ester compound, for example, a compound represented by the general formula (VI):

[0037]

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And monophosphate or polyphosphate. The above general formula (V
In I), R ^{1 to} R ⁴ each represent an optionally substituted aryl group, which may be the same or different. X represents an arylene group which may have a substituent, and c, d, e and f each represent 0
Or 1, p shows the number of 0-5. This p is represented by the average value of p of each phosphate ester when two or more phosphate esters are used as a mixture. As the substituent in the aryl group and the arylene group, for example, 1 to 1 carbon atoms
Examples include an alkyl group having 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group such as a phenyl group and a tolyl group. One of these substituents may be introduced, or a plurality of these may be introduced.

Examples of the non-halogen-containing phosphate compound represented by the general formula (VI) include monophosphate esters such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, and tribiphenyl phosphate; Resorcinol polyphosphate, phenyl hydroquinone polyphosphate,
Phenyl cresyl resorcin polyphosphate, phenyl cresyl hydroquinone polyphosphate, tetraphenyl resorcin diphosphate, tetraphenyl hydroquinone diphosphate, phenyl tricresyl resorcin diphosphate, phenyl tricresyl hydroquinone diphosphate, tetrabiphenyl resorcin Examples include polyphosphates such as diphosphate and tetrabiphenyl hydroquinone diphosphate. Among these, polyphosphate esters are preferred from the viewpoint of suppressing mold adhesion and contamination during thermoforming of the polycarbonate resin composition. Also,
These monophosphates and polyphosphates may be used alone or in combination of two or more.

In the composition of the present invention, the halogen-free phosphate compound of component (F), which is used as necessary, is composed of the polycarbonate resin of component (A) and the titanium oxide powder of component (B). Based on the total weight of
It is contained in a proportion of 0.05 to 1 part by weight as a phosphorus element. If the content of the phosphorus element is less than 0.05 part by weight, the effect of improving flame retardancy and the synergistic effect on titanium oxide may not be sufficiently exhibited. There is not much improvement in effectiveness,
Rather, it is economically disadvantageous and the molded article tends to have reduced heat resistance. From the viewpoints of the effect of improving the flame retardancy, the heat resistance of the molded article, the economic efficiency, and the like, a particularly preferable content of the phosphorus element is based on the total weight of the component (A) and the component (B).
It is in the range of 0.1 to 0.5 parts by weight.

In the composition of the present invention, when particularly high flame retardancy is required, polytetrafluoroethylene having a fibril-forming ability may be used as a component (G) if necessary. Resin dripping inhibitor)
Can be contained. Here, the fibril-forming ability refers to the ability to fibrillate (fibrillate) when subjected to the shearing stress of plasticization in kneading or injection molding, and is effective in obtaining high flame retardancy.

Polytetrafluoroethylene (PTFE) having a fibril-forming ability as described above can be prepared, for example, by adding tetrafluoroethylene in an aqueous solvent in the presence of sodium, potassium or ammonium oxydisulfide under a pressure of about 1 to 100 psi. , Temperature 0-200 ° C
To a degree, preferably from 20 to 100 ° C.

The type of PTFE having fibril-forming ability thus obtained is not particularly limited, but for example, those classified into type 3 in the ASTM standard are preferable. Specific products include Teflon 6
J (trade name, manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.), Polyflon TFE D-1, Polyflon TFE F-10
4 (trade name, manufactured by Daikin Industries, Ltd.). Other than those classified into Type 3, for example, Algoflon F5 (trade name, manufactured by Montefluos), Polyflon MP
A FA-100 and polyflon TFE F201
(Trade name, manufactured by Daikin Industries, Ltd.).

The polytetrafluoroethylene having the fibril-forming ability of the component (G) may be used alone or in combination of two or more. In the composition of the present invention, the content of the polytetrafluoroethylene having fibril-forming ability of the component (G), which is optionally used, is not particularly limited, but the polycarbonate resin of the component (A) and the polycarbonate resin of the component (B) are used. The range of 0.01 to 1 part by weight is advantageous, based on the total weight of the components with the titanium oxide powder. If the amount is less than 0.01 part by weight, the effect of preventing dropping may not be sufficiently exhibited, and if it exceeds 1 part by weight, the effect is not so much improved for the amount, and it is economically disadvantageous. .

In the composition of the present invention, it is preferable to use a light diffusing agent as the component (H), if necessary, to further improve the light reflectivity. Examples of the light diffusing agent include silica beads, acryl beads, glass beads, silicone resin beads, and core-shell type elastomer beads made of silicone and acryl, and maintain flame retardancy. From the viewpoint of improving light reflectivity, silica beads are particularly preferred.
The particle size of the light diffusing agent is preferably about 0.5 to 20 μm, and the silica bead is particularly preferably about 1 to 2 μm.

The addition amount is 0.05 to 5 parts by weight, and the silica beads are particularly preferably about 0.05 to 0.2 parts by weight. Outside this range, the light reflectivity decreases. In the composition of the present invention, a stilbene bisbenzoxazole derivative is used as a component (I), if necessary, to improve the light reflectivity. This is, without impairing the light resistance and heat resistance of the polycarbonate resin composition,
It has an effect as a lightness improver for increasing light reflectance.

Examples of this stilbenebisbenzoxazole derivative include compounds of the formula (VII)

[0048]

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4- (benzoxazole-2)
-Yl) -4 '-(5-methylbenzoxazol-2)
-Yl) stilbene or formula (VIII)

[0050]

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4,4'-bis (benzoxazol-2-yl) stilbene and the like. Examples of the compound represented by the formula (VII) include Hostalx KS (trade name, manufactured by Hoechst), and examples of the compound represented by the formula (VIII) include yeast bright OB-1 (trade name). Eastman Chemical Co., Ltd.) is commercially available.

In the present invention, the stilbenebisbenzoxazole derivative of the component (I) may be used alone.
Two or more kinds may be used in combination. Further, at least one pigment selected from blue and purple pigments may be mixed and used in an appropriate amount. As a mixture of a stilbene bisbenzoxazole derivative and a blue or purple pigment, for example, Hostalx KS-N (trade name, manufactured by Hoechst), East Bright OB-3 (trade name, manufactured by Eastman Chemical Company), and the like are commercially available. I have.

The content of the stilbene bisbenzoxazole derivative of the component (I) in the composition of the present invention is as follows:
It is selected in the range of 1 to 1000 ppm by weight based on the total weight of the polycarbonate resin (A) and the titanium oxide powder (B). This content is 1 ppm by weight.
If the amount is less than 1000 ppm, the effect of improving the light reflectance may not be sufficiently exhibited. If the amount exceeds 1000 ppm by weight, the effect is not so much improved for the amount thereof, which is rather economically disadvantageous. From the viewpoints of the effect of improving the light reflectivity and the economical efficiency, the preferred content of the component (I) is in the range of 10 to 500 ppm by weight based on the total weight of the components (A) and (B). .

The flame-retardant polycarbonate resin composition of the present invention may optionally contain various additives such as other antioxidants, lubricants (release agents), and other inorganic materials, as long as the object of the present invention is not impaired. A filler or the like may be appropriately contained. The flame-retardant polycarbonate resin composition of the present invention comprises, for example, the components (A), (B), (C), (D),
(E) component and (F) component used as required,
It can be prepared by blending (G) component, (H) component, (I) component and various additives and kneading them. As the compounding and kneading method, a method applied to a usual resin composition can be applied as it is, and a ribbon blender, a Henschel mixer, a Banbury mixer, a drum tumbler, a single screw or a multi-screw extruder having two or more screws, a co-kneader and the like can be used. The method used is preferred. The kneading temperature is not particularly limited, but is usually suitably selected from the range of 240 to 340 ° C.

The thus obtained resin composition is formed into a flat plate or a curved plate by a usual molding method, for example, an injection molding method or a compression molding method. can get. This light beam reflection plate is preferably used, for example, for a lighting device or a liquid crystal display backlight, but is particularly suitable as a liquid crystal display backlight reflection plate.

Since the light reflecting plate of the present invention does not contain a bromine compound in its material, it has excellent light resistance, has a small decrease in reflectivity even when used for a long period of time, and shows good characteristics. It has excellent characteristics.

[0057]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The types of materials used in Examples and Comparative Examples are as follows. (A) Polycarbonate (PC resin) Teflon FN1900A (trade name, manufactured by Idemitsu Petrochemical, bisphenol A type polycarbonate, viscosity average molecular weight 19000): Abbreviated as 1900A. : CR63
(C) Antistatic agent Dodecylbenzenesulfonic acid phosphonium salt (IPS-101 made by Takemoto Yushi): Abbreviated as IPS-101 Dodecylbenzenesulfonic acid sodium salt (Elecut S-412 made by Takemoto Yushi): Abbreviated as S-412 Secondary alkane sulfonate sodium salt (Hosttapur SAS93 manufactured by Hoechst Japan): SA
Abbreviated as S93 Stearic acid monoglyceride (Rikemar S100A manufactured by RIKEN Vitamin): Abbreviated as S100A (D) Phosphorus antioxidant triphenylphosphine (JC26 manufactured by Johoku Chemical)
3): Abbreviated as JC263 Penta-Eristo-Lulfite (Asahi Denka Kogyo Co., Ltd.)
ADK STAB PEP36): Abbreviated as PEP36 Octadecyl-3- (3,5-di-t-butyl-hydroxyphenyl) propionate (Irganox 1076 manufactured by Ciba Specialty): Irg. Abbreviated as 1076 Pentaerythyl-tetrakis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propione
G] (Irganox 1010 manufactured by Ciba Specialty)
): Irg. Abbreviated as 1010 (E) Organopolysiloxane methoxy-modified silicone BY16-160 (trade name, manufactured by Dow Corning Toray Silicone Co., Ltd.): Silicone B
Abbreviated as Y16-160 (F) Halogen-free phosphate ester ADK STAB PFR [trade name, manufactured by Asahi Denka Kogyo KK, phenyl resorcinol polyphosphate, phosphorus content 10.
(G) Fibril-forming polytetrafluoroethylene PTFE FA-100 [trade name, Daikin Industries, Ltd.]
Abbreviated as FA-100) (H) Light diffusing agent silica beads (P-600 manufactured by Catalysis Chemical Industry): P60
Abbreviated as 0 (I) Brightness improver Hostalx KS-N (trade name, manufactured by Hoechst): K
The performance of the polycarbonate resin composition was evaluated according to the following procedure. (A) Reflectance: 3.2 × 2.5 × 0.1 cm square plate at 280 ° C.
To form a sample. LCM Spectrophotometer MS2020
Evaluation was made based on the Y value of Plus (manufactured by Macbeth). (B) Flame retardant UL94: A vertical combustion test was performed on each sample having a thickness of 3 mm and 1.5 mm according to UL94. (C) Transmittance: SZ Sigma 9 manufactured by Nippon Denshoku Industries Co., Ltd.
The measurement was performed according to JIS K7105 using 0. (D) Heat aging resistance: 100 ° C, 100 ° C in a gear oven
The color difference (ΔE) before and after standing for 0 hours was measured using a spectrophotometer (MS2020 Plus manufactured by Macbeth). (E) Surface resistivity: 80 in accordance with JIS K6911
Using a × 80 × 3.2 mm square plate, it was measured after conditioning for 24 hours after molding. The unit was expressed in Ω / □. (F) Dust adhesion amount: After being placed at a distance of 1 cm under a fluorescent lamp and left for one week, the presence or absence of dust adhesion was visually observed.

Examples 1 to 6 and Comparative Examples 1 to 4 Each component of the type and amount shown in Tables 1 and 2
The mixture was melt-kneaded with a φ single screw extruder at a cylinder temperature of 280 ° C. and a screw rotation speed of 100 rpm, extruded and pelletized to prepare a resin composition. In addition, some liquids were melt-kneaded while being supplied by a metering pump. After the obtained pellets were dried at 120 ° C. for 5 hours, they were injection-molded to prepare test pieces for measuring physical properties.

The results of the performance evaluation of the resin composition are shown in Tables 1 and 2.

[0060]

[Table 1]

[0061]

[Table 2]

As can be seen from Tables 1 and 2, Examples 1 to 6 maintain a high flame retardancy because all of them use a combination of a specific antistatic agent and a specific antioxidant. In addition, it has properties that are remarkably excellent in heat aging resistance. In all of Examples 5 to 6, since the light diffusing agent and the brightness improver are used, improvement in transmittance is recognized. Comparative Examples 1 and 2 are inferior in flame retardancy and heat aging resistance because no specific antistatic agent is used, and have low reflectance. Comparative Examples 3 and 4 are inferior in heat aging resistance because no specific antioxidant is used.

[0063]

Industrial Applicability The flame-retardant polycarbonate resin composition of the present invention has high reflectivity, light-shielding property, heat-aging resistance, dust-resistance, etc., without impairing mechanical properties such as flame-retardancy and impact resistance. It is preferably used as a material such as a light beam reflecting plate. The light-reflecting plate of the present invention obtained by molding this resin composition does not contain a bromine compound, so it has excellent heat aging resistance, has a small decrease in reflectance even after long-term use, and is used for lighting devices. It is useful as a light reflector or a reflector for a liquid crystal display backlight.

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Claims (7)

[Claims] 1. A composition comprising (A) a polycarbonate resin and (B) a titanium oxide powder in a weight ratio of 70:30 to 90:10, and a total weight of the components (A) and (B). (C) 1 to 8 parts by weight of an alkylbenzenesulfonic acid-based antistatic agent (D) 100 to 3000 ppm by weight of a phosphorus-based antioxidant and (E) 0.01 to 5 parts by weight of an alkoxy group-containing organopolysiloxane. A flame-retardant polycarbonate resin composition containing parts by weight. 2. A halogen-free phosphate ester compound (F) in an amount of 0.05 to 1 part by weight as a phosphorus element based on 100 parts by weight of the total of the components (A) and (B). 2. The flame-retardant polycarbonate resin composition according to 1. 3. The composition according to claim 1, further comprising (G) 0.01 to 1 part by weight of polytetrafluoroethylene having a fibril-forming ability, based on 100 parts by weight of the total of the components (A) and (B). Or the flame-retardant polycarbonate resin composition according to 2 above. 4. The method according to claim 1, further comprising (H) 0.05 to 5 parts by weight of a light diffusing agent based on 100 parts by weight of the total of the components (A) and (B). The flame-retardant polycarbonate resin composition as described in the above. 5. The composition of claim 1, further comprising (I) 1 to 1000 ppm by weight of a stilbenebisbenzoxazole derivative based on the total weight of the components (A) and (B).
5. The flame-retardant polycarbonate resin composition according to any one of 4. 6. A light reflector formed by molding the flame-retardant polycarbonate resin composition according to claim 1. 7. The light reflector according to claim 6, which is a reflector for a liquid crystal display backlight.