KR20070018801A - Light-colored polycarbonate compositions and methods - Google Patents

Abstract

Bulk polycarbonate-containing resin components; An amount of polycarbonate-siloxane copolymer sufficient to provide at least 3% by weight of siloxane of the total weight of the composition; And a colorant composition comprising titanium dioxide having an organic coating, such as a coating comprising polysiloxane, wherein the amount of titanium dioxide is 1 to 2.5% by weight, preferably 1 to 2.0% by weight, more preferably of the total weight of the composition. Preferably from 1 to 1.5% by weight), both light color and good flame retardancy. Such compositions can be used to produce shaped articles, in particular articles having a thin wall area that achieves a V0 UL fire rating at the first thickness.

Description

Lightly colored polycarbonate composition and its preparation method {LIGHT-COLORED POLYCARBONATE COMPOSITIONS AND METHODS}

FIELD OF THE INVENTION The present invention relates to polycarbonate compositions, and more particularly to polycarbonate / styrene based molding compositions colored with titanium dioxide to produce white or other light colored products.

Generally, the blend of polycarbonate resin and styrene includes rubber particles, such as polybutadiene, which act as an impact modifier. However, the addition of graft rubber to polycarbonate / styrene blends results in a reduction in the flame retardancy of the blend, requiring the addition of flame retardants that can adversely affect the high temperature properties of the material.

Summary of the Invention

The present invention provides a bulk resin component comprising (a) a polycarbonate; (b) an amount of polycarbonate-siloxane copolymer sufficient to provide at least 3% by weight or more of the siloxane of the total weight of the composition; And (c) a colorant composition comprising titanium dioxide having an organic coating, such as a coating comprising polysiloxane, wherein the amount of titanium dioxide is from 1 to 2.5% by weight, preferably from 1 to 2.0% by weight of the total weight of the composition. , More preferably 1 to 1.5% by weight).

In addition, the present invention (a) a bulk resin component containing a polycarbonate; (b) polycarbonate-siloxane copolymers; And (c) a molding composition comprising a colorant composition comprising titanium dioxide, the shaped article having a wall thickness of at least a first thickness.

Titanium dioxide has an organic coating and the amount of polycarbonate-siloxane copolymer is selected such that the molding composition achieves a V0 UL fire rating at the first thickness.

The present invention also relates to a bulk resin component comprising (a) a polycarbonate; (b) an amount of polycarbonate-siloxane copolymer sufficient to provide at least 3% by weight or more of the siloxane of the total weight of the composition; And (c) a colorant composition comprising titanium dioxide having an organic coating, such as a coating comprising polysiloxane, wherein the amount of titanium dioxide is from 1 to 2.5% by weight, preferably from 1 to 2.0% by weight of the total weight of the composition. Forming a blend, more preferably 1 to 1.5% by weight); And a step of molding the product from the blend to provide a method of molding a lightly colored flame retardant polycarbonate product.

The present invention also includes the steps of (a) including a polycarbonate-siloxane copolymer in an amount sufficient to provide at least 3% by weight or more of the siloxane of the total weight of the composition; And (b) selecting titanium dioxide having an organic coating, such as a coating comprising polysiloxane, as titanium dioxide, the bulk resin component comprising polycarbonate; Polycarbonate-siloxane copolymers; And it provides a method for improving the flame retardancy of the lightly colored composition comprising a colorant composition comprising titanium dioxide.

1 shows the relationship of p (FTP) to% TiO ₂ at various levels of the polycarbonate-siloxane copolymer.

Numerical values in the specification and claims of the present application represent average values for compositions that may contain individual polymers having different properties, especially as they relate to polymer composition. Moreover, these numerical values are intended to include the same numerical values as would have been reduced to the same number of valid figures and numerical values other than the stated values less than the experimental error of the measurement technique used in this application to determine the values. It must be understood.

As mentioned above, the addition of styrene-based impact modifiers to polycarbonates has a known detrimental effect on the flame retardancy of the composition. This problem can be overcome by adding a polycarbonate-siloxane copolymer. However, the inventors have observed that addition of titanium dioxide to the polycarbonate / polycarbonate-siloxane copolymer blend in order to obtain a light-colored product results in a reduction in the flame retardant properties of the composition. Has come. The present invention provides a battery charger for computer and business machine housings, the telecommunications industry and the electrical industry, by providing a lightly colored composition which avoids such reductions in product quality even when a rubbery impact modifier is present. It provides a useful heat resistant lightly colored material that can be used for a variety of applications including battery chargers.

In a first embodiment, the present invention provides a titanium dioxide-containing polycarbonate blend comprising a bulk polycarbonate resin, a polycarbonate-siloxane copolymer, and an organic-coated titanium dioxide. In another embodiment, the compositions of the present invention also include rubber impact modifiers and / or flame retardant effective amounts of flame retardants.

The term "lightly-colored" as used in the specification and claims of the present application, refers to any coloring of a polymer blend comprising titanium dioxide as one component of the colorant composition used. Refer. In particular, the term lightly colored includes the coloration achieved by mixing titanium dioxide with soluble dyes, as well as the white, cream, tannin and gray coloration achieved by combining titanium dioxide with other fillers or pigments of various colors. do.

The term "bulk polycarbonate resin" as used in the specification and claims of the present application refers to the polycarbonate resin used as the base component of the composition. There are many known polycarbonate resin formulations, and the proportion of bulk polycarbonate resin in a given composition is chosen to achieve the properties required for a given application. Thus, the bulk polycarbonate may be a high temperature polycarbonate, which polycarbonate is chosen to have good flow properties that do not contradict molding applications or extrusion. In general, the bulk phase component will be at least 50% or more of the total composition. In some embodiments, the bulk phase component is at least 75% of the total composition.

Bulk phase components include polycarbonate resins that may be in single form or in the form of a mixture of two or more polycarbonate homopolymers and / or copolymers. The polycarbonate (s) may be prepared by an interfacial process or melt transesterification process. In the most common embodiment of the interfacial process, bisphenol A (BPA) and phosgene react to form a polycarbonate. When a melt transesterification process is used, polyaryl is produced by reacting diaryl carbonate and dihydric phenol. Techniques for carrying out the melt transesterification reaction are well known and are described, for example, in Organic Polymer Chemistry by KJ Saunders, 1973, Chapman and Hall Ltd., as well as many US patents, for example US Pat. No. 3,442,854 number; 5,026,817; 5,026,817; 5,097,002; No. 5,142,018; 5,151,491; And 5,340,905. As is known in the art, there are many diaryl carbonates and dihydric phenols that can be used. The particular diaryl carbonate and particular dihydric phenol selected will depend on the nature of the polycarbonate desired. Typical diaryl carbonates that can be used include diphenyl carbonate, dialtolyl carbonate, bis (chlorophenyl) carbonate; m-cresyl carbonate; Dynaphthyl carbonate; Bis (diphenyl) carbonate; Diethyl carbonate; Dimethyl carbonate; Dibutyl carbonate; And dicyclohexyl carbonate, but are not limited to these. Common dihydric phenols include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (also bisphenol A ), 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2 -Bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane and 2,2-bis (4-hydroxy-3-bromophenyl Bis (hydroxyaryl) alkanes such as) propane; Bis (hydroxyaryl) cycloalkanes such as 1,1- (4-hydroxyphenyl) cyclopentane and 1,1- (4-hydroxyphenyl) cyclohexane; Dihydroxyaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethylphenyl ether; Dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; Dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; And dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone. In one general polycarbonate, the aromatic dihydroxy compound is bisphenol A (BPA) and the diaryl carbonate is diphenyl carbonate.

The polycarbonate resin used in the present invention includes a repeating structural unit of formula (I).

Where

At least about 60% or more of the total number of R ¹ groups are aromatic organic radicals, and the rest are aliphatic, cycloaliphatic or aromatic radicals.

Preferably, R ¹ is an aromatic organic radical, more preferably a radical of formula II.

Where

A ¹ and A ² are each monocyclic divalent aryl radicals,

Y ¹ is a bridging radical having 1 or 2 atoms that separates A ¹ from A ² .

In one exemplary embodiment, one atom separates A ¹ from A ² . Exemplary non-limiting examples of this type of radical include -O-, -S-, -S (O)-, -S (O) _2- , -C (O)-, methylene, cyclohexyl-methylene, 2- [2.2.1] -bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadedecidene, cyclododecylidene and adamantylidene. The bridging radical Y ¹ may be a hydrocarbon group or saturated hydrocarbon group such as methylene, cyclohexylidene or isopropylidene.

Preferred polycarbonates are based on bisphenol A, wherein A ¹ and A ² are each p-phenylene and Y ¹ is isopropylidene. The average molecular weight of the polycarbonate is preferably in the range of about 5,000 to about 100,000, more preferably in the range of about 10,000 to about 65,000, and most preferably in the range of about 15,000 to about 35,000. When present, the polycarbonate resin is used in an amount of about 1 to about 99 weight percent based on the total weight of the composition. The polycarbonate resin is preferably present in an amount of about 1 to about 95 weight percent, more preferably about 5 to about 90 weight percent, and most preferably about 5 to about 85 weight percent, based on the total weight of the composition. .

In addition to the linear homo-polycarbonates, the bulk polycarbonate resin component may contain two or more different dihydric phenols, or copolymers of these dihydric phenols with glycols or copolymers with hydroxy- or acid-terminated polyesters. Hetero-polycarbonate species, including copolymers or copolymers with dibasic acids or hydroxy acids. Polyarylates and polyester-carbonate resins or blends thereof may also be used. As well as branched polycarbonates, blends of linear polycarbonates and branched polycarbonates are also useful. Branched polycarbonates can be prepared by adding a branching agent during the polymerization. Such branching agents are well known and may include multifunctional organic compounds containing at least three functional groups which may be hydroxyl, carboxyl, carboxylic anhydride, haloformyl and mixtures thereof. Specific examples thereof include trimellitic acid, trimellitic anhydride, trimellitic acid trichloride, tris-p-hydroxy phenyl ethane, isatin-bis-phenol, tris-phenol TC (1,3,5-tris (( p-hydroxyphenyl) -isopropyl) benzene), tris-phenol PA (4 (4 (1,1-bis (p-hydroxyphenyl) -ethyl) alpha, alpha-dimethyl benzyl) phenol), 4- Chloroformyl phthalic anhydride, trimesic acid and benzophenone tetracarboxylic acid. Branching agents can be added at a level of about 0.05-2.0% by weight. Procedures for making branching agents and branched polycarbonates are described in US Pat. Nos. 3,635,895 and 4,001,184, which are incorporated herein by reference. All types of polycarbonate end groups are expected to be useful in polycarbonate compositions.

Bulk polycarbonate resins may also include blends of polycarbonate (s) with other non-polycarbonate-based thermoplastics. Non-limiting examples of such thermoplastics that may be included in the bulk component include (a) a polymer comprising an aromatic vinyl monomer as the structural component; (b) a polymer comprising an aromatic vinyl monomer and a vinyl cyanide monomer as structural components; (c) polymers comprising aromatic vinyl monomers, vinyl cyanide monomers and rubber like polymers as structural components; (d) aromatic polyesters; (e) polyphenylene ether; (f) polyether imides; And (g) polyphenylene sulfides. Specific examples of such ancillary thermoplastics are styrene acrylonitrile copolymers and polymethyl (methacrylate).

Siloxane-polycarbonate block copolymers are known for their low temperature ductility and flame retardancy, and can also be used as matrices for incorporating phosphorescent pigments. Such block copolymers can be prepared by introducing phosgene into a mixture of dihydric phenol such as BPA and hydroxyaryl-terminated polydiorganosiloxane under interfacial reaction conditions. Tertiary amine catalysts may be used to promote polymerization of the reactants.

Polycarbonate-siloxane copolymers useful in the compositions of the present invention are known, for example, from US Pat. Nos. 4,746,701, 4,994,532, 5,455,310 and 6,252,013, which are incorporated herein by reference, and are made by General Electric Co. General Electric Company) is marketed under the trade name LEXAN ST. Mitsubishi Engineering Plastics contains 100 parts by weight (pts.wt) of (A) (a) 1-99 weight percent polycarbonate resin and (b) 99-1 weight percent polycarbonate-organopolysiloxane copolymer. Polycarbonate type resins; (B) 0.1-5 pts. wt. phosphate type compound; And (C) 0.2-2 pts. A polycarbonate type resin composition is described comprising wt. fibrillated-forming polytetrafluoroethylene (JP 10007897). The polycarbonate-polysiloxane copolymers disclosed above may also be used in the present invention.

In general, polycarbonate-siloxane copolymers useful in the present invention are formed from polycarbonate blocks and poly (diorganosiloxane) blocks. The polycarbonate block comprises a repeating structural unit of formula (I) wherein at least about 60% of the total number of R ¹ groups are aromatic organic radicals and the remainder are aliphatic, cycloaliphatic or aromatic radicals. R ¹ is preferably an aromatic organic radical, more preferably Formula II (wherein A ¹ and A ² are each monocyclic divalent aryl radicals, and Y ¹ is 1 or 1 which separates A ¹ from A ² or Radicals having two atoms). In one exemplary embodiment, one atom separates A ¹ from A ² . Exemplary non-limiting examples of this type of radical include -O-, -S-, -S (O)-, -S (O) _2- , -C (O)-, methylene, cyclohexyl-methylene, 2- [2.2.1] -bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadedecidene, cyclododecylidene and adamantylidene. The bridging radical Y ¹ may be a hydrocarbon group or saturated hydrocarbon group such as methylene, cyclohexylidene or isopropylidene.

Poly (diorganosiloxane) blocks include repeating structural units of formula III.

Where

Each R 2 may be the same or different and C (1-13) 1 is selected from organic radicals,

n is an integer of 1 or more, preferably about 10 or more, more preferably about 25 or more, most preferably about 40 or more.

n is preferably an integer of about 1000 or less, preferably about 100 or less, more preferably about 75 or less, and most preferably about 60 or less. For easy understanding by those of ordinary skill in the art, n represents an average value.

In a preferred embodiment, the poly (diorganosiloxane) block comprises a repeating structural unit of formula IV.

Where

Each R may be the same or different and is selected from the group consisting of hydrogen, halogen, C (1-8) alkoxy, C (1-8) alkyl and C (6-13) aryl radicals,

R 1 is a C (2-8) divalent aliphatic radical,

R 2 is selected from the same or different C (1-13) monovalent organic radicals,

n is an integer of 1 or more, preferably about 10 or more, more preferably about 25 or more, most preferably about 40 or more.

In addition, n is preferably an integer of 1000 or less, preferably 100 or less, more preferably about 75 or less and most preferably about 60 or less. In one embodiment n is 50 or less.

Particularly preferred hydroxyaryl-terminated polydiorganosiloxanes are compounds wherein R2 is methyl and R is ortho-positioned to phenolic substituents as hydrogen or methoxy and R1 is ortho or para-positioned to phenolic substituents as propyl. Compound.

Some of the radicals included in R in the above formulas include halogen radicals such as bromo and chloro; Alkyl radicals such as methyl, ethyl and propyl; Alkoxy radicals such as methoxy, ethoxy and propoxy; Aryl radicals such as phenyl, chlorophenyl and tolyl. Radicals included in R 3 are, for example, dimethylene, trimethylene and tetramethylene. Radicals included in R4 include, for example, C (1-8) alkyl radicals, haloalkyl radicals such as trifluoropropyl and cyanoalkyl radicals; Aryl radicals such as phenyl, chlorophenyl and tolyl. R 4 is preferably methyl, or a mixture of methyl and trifluoropropyl, or a mixture of methyl and phenyl.

The siloxane-polycarbonate block copolymers have a weight average molecular weight (Mw, eg, measured by gel permeation chromatography, ultracentrifugation or light scattering) of at least about 10,000, preferably at least about 20,000. It is also desirable to have a weight average molecular weight of about 200,000 or less, preferably about 100,000 or less. Generally, it is preferred that the polyorganosiloxane units comprise about 0.5 to about 80 weight percent of the total weight of the siloxane-polycarbonate copolymer. The chain length of the siloxane block corresponds to about 10 to about 100 chemically bound organosiloxane units. They can be prepared, for example, as described in US-A-5,530,083, which is incorporated herein by reference.

 In the examples below, the polycarbonate-siloxane copolymer has a siloxane content of 20% by weight and a block length of 50 units of poly (diorganosiloxane) based on the total weight of the copolymer (n in Formulas III and IV). ) Is LEXAN ST (General Electric), a polycarbonate / polydimethylsiloxane (PC / PDMS) copolymer. The composition according to the invention as described in the examples comprises a polycarbonate-siloxane copolymer comprising at least 18% by weight of the total weight of the composition, for example 18-40% by weight, preferably 18-30% by weight, Preferably in an amount of 18 to 25% by weight. However, in these examples, the specific polycarbonate-siloxane copolymer used contained 20 weight percent siloxane. Since the siloxane ratio of the copolymer is believed to be involved in achieving the results of the present invention, another more general expression of the amount of copolymer is based on the amount of silicone in the total composition. Thus, the amount of polycarbonate-siloxane copolymer in the composition of the present invention is suitably expressed as an amount sufficient to provide an amount of at least 3% by weight, for example 3.6% by weight, of the total weight of the composition.

The composition of the present invention also contains a colorant composition containing titanium dioxide. The choice of titanium dioxide component is important in the context of the present invention, as some titanium dioxide materials, as described in the comparative examples, cause a significant reduction in the flame retardancy of the composition. Although not limited to specific mechanisms, it is believed that the degeneration of these properties is caused by black pigments such as carbon black and different distributions of titanium dioxide formulations that cause unsuitable results. Specifically, the results of microscopic evaluation show that the black pigment particles are fairly evenly dispersed, while the undesirable type of titanium dioxide apparently aggregates with the siloxane of the polycarbonate-siloxane copolymer. The present invention alleviates this problem by maintaining a minimum level of polycarbonate-siloxane copolymer that depends on the thickness of the material to be molded and by using titanium dioxide with an organic coating and optionally an additional inorganic coating. Commercially useful TiO ₂ pigments are typically prepared from colloidal suspensions which have chemically immobilized the pigment surface by adding low levels of alumina. Subsequently, a secondary organic coating, such as an organo-silicon coating, is applied to further reduce surface reactivity to improve the handling characteristic. Sometimes the correct coating formulation is owned by the supplier, but in general organic compositions and general compositions with or without Al ₂ O ₃ are known. Specific examples of suitable commercially available titanium dioxide preparations include Tioxide R-FC5 (Huntsman) (product of small crystals coated with TMP (trimethylolpropanol), PDMS (polydimethylsiloxane) and Al ₂ O ₃ ); Titafrance RL91 (product of small crystals coated with 1.2% PDMS silicone oil); And Kronos 2230 (crystal product of normal size coated with PDMS polysiloxane and Al ₂ O ₃ ). Based on the results of using these materials, the present invention includes TiO ₂ with organic coatings, in particular organic coatings comprising polysiloxanes, TMP or mixtures thereof.

The amount of titanium dioxide is suitably 1 to 2.0% by weight, preferably 1 to 1.5% by weight of the total weight of the composition. As the amount of polycarbonate-siloxane copolymer increases, the amount of titanium dioxide increases.

In addition to titanium dioxide, the colorant composition may include dyes, pigments or other colorants that combine with titanium dioxide such that overall light coloration occurs in the composition. In addition, the colorant composition may be a metal-effect pigment, a metal oxide-coated metal pigment, a plate graphite pigment, a plate-like molybdenum disulfide pigment, a pearl mica pigment, a metal oxide-coated mica pigment, an organic-effect pigment, a laminated It may also comprise visible effect materials such as optical interference pigments, polymeric holographic pigments or liquid crystal interference pigments. In one embodiment, the effect pigments are aluminum, gold, brass and copper metal effect pigments; In particular a metal effect pigment selected from the group consisting of aluminum metal effect pigments. In another embodiment, the effect pigments consist of copper phthalocyanine blue, copper phthalocyanine green, carbazole dioxazine, diketopyrrolopyrrole, iminoisoindolin, iminoisoindolinone, azo and quinacridone effect pigments. Pearl mica pigments or large particle sizes, preferably platy organic effect pigments selected from the crowd.

Optionally, the thermoplastic composition may comprise a rubbery impact modifier. When present, the impact modifier copolymer resin is suitably added to the thermoplastic composition in an amount of about 1 to 30 weight percent, and one or two or more of various different rubbery modifiers such as graft or nose shell rubber Combinations of modifiers. Acrylic rubber, ASA rubber, diene rubber, organosiloxane rubber, EPDM rubber, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS) rubber, ABS rubber, MBS rubber and Groups known as glycidyl ester impact modifiers are suitable.

Such compositions may also include anti-drip agents such as fluoropolymers. The fluoropolymer may be a fibrillated or non-fibrillated fluoropolymer. Preferably, the fluoropolymer is a fibril forming polymer. In some embodiments, the preferred fluoropolymer is polytetrafluoroethylene. In some embodiments, it is desirable to use an encapsulated fluoropolymer, i.e., a fluoropolymer encapsulated within the polymer, as anti-drip agent. Encapsulated fluoropolymers can be prepared by polymerizing the polymer in the presence of the fluoropolymer. Alternatively, the fluoropolymer may be substituted with a second polymer such as, for example, an aromatic polycarbonate resin or a styrene-acrylonitrile resin, for example, in US Pat. Nos. 5,521,230 and 4,579,906. There are several ways to pre-blend to form agglomerated materials for use as antidrip agents. Either method can be used to produce an encapsulated fluoropolymer.

Fluoropolymers in encapsulated fluoropolymers include fluoropolymers having a melting point of about 320 ° C. or higher, such as polytetrafluoroethylene. Preferred encapsulated fluoropolymers are styrene-acrylonitrile copolymers encapsulated polytetrafluoroethylene (ie TSAN). TSAN can be prepared by copolymerizing styrene and acrylonitrile in the presence of an aqueous dispersion of polytetrafluoroethylene (PTFE). TSAN can include, for example, about 50 wt% PTFE and about 50 wt% styrene-acrylonitrile copolymer based on the total weight of the encapsulated fluoropolymer. The styrene-acrylonitrile copolymer may include, for example, about 75 wt% styrene and about 25 wt% acrylonitrile, based on the total weight of the copolymer. TSAN offers significant advantages over polytetrafluoroethylene, ie TSAN is more readily dispersed in the composition.

If present, anti-drip agents are present in an amount effective to reduce the likelihood of dropping, for example from 0.1 to 1.4% by weight, more generally from 0.5 to 1% by weight.

The composition of the present invention may also contain a flame retardant effective amount of a flame retardant. Flame retardants may include phosphate flame retardants or sulfonate flame retardants. If the composition comprises a flame retardant component such as an alkyl aromatic copolymer, it is preferred that the flame retardant comprises an organic phosphate flame retardant. The organic phosphate flame retardant is preferably an aromatic phosphate compound of the formula (V).

Where

Each R ⁷ is the same or different and is alkyl, cycloalkyl, aryl, alkyl substituted aryl, halogen substituted aryl, aryl substituted alkyl, halogen or a combination of any of the foregoing, provided that at least one R ⁷ is aryl.

Suitable phosphate-based flame retardants are based not only on resorcinol, for example resorcinol tetraphenyl diphosphate, but also on the basis of bisphenols, for example bisphenol A tetraphenyl diphosphate (BPADP). Include things. Phosphates containing substituted phenyl groups are also suitable.

The flame retardant material may also be sulfonates such as Rimar salt (potassium perfluorobutane sulfonate) and potassium diphenylsulfone sulfonate. See also the perfluoroalkane sulfonate described in US Pat. No. 3,775,367, which is incorporated herein by reference.

In addition, the compositions of the present invention may also include other optional components of the type commonly used in polycarbonate compositions. Such components include, but are not limited to, antioxidants, UV stabilizers, mold release agents, fillers (eg, clays, wollastonite or talc), reinforcing agents such as glass fibers, and antistatic agents.

The present invention also provides a product having flame retardant properties, for example a molded product or an extruded product. When evaluating the flame retardancy of a polycarbonate product, the point where the wall thickness is minimal is taken into account because this area of the product is the most flammable. In the scope of the claims of this application, the minimum wall thickness is referred to as the "first thickness", and the article comprises (a) a bulk polycarbonate resin component; (b) polycarbonate-siloxane copolymers; And (c) a colorant comprising titanium dioxide, wherein the titanium dioxide has an organic coating and the amount of polycarbonate-siloxane copolymer is such that the molding composition has a V0 UL fire rating rating at the first thickness. Is chosen to achieve. Thus, the desired amount of polycarbonate-siloxane copolymer depends on the minimum thickness of the product, the amount of titanium dioxide and the type of organic coating. Suitable amounts at different thicknesses may vary somewhat depending on other components in the molding composition, but the following values provide exemplary criteria.

The compositions of the present invention are suitably used in the process of forming lightly colored flame retardant polycarbonate products. Such methods include (a) bulk polycarbonate resin components; (b) an amount of polycarbonate-siloxane copolymer sufficient to provide at least 3% by weight or more of the siloxane of the total weight of the composition; And (c) forming a blend comprising a colorant composition comprising titanium dioxide, wherein the amount of titanium dioxide is 1 to 2.0 weight percent of the total weight of the composition; And forming a product from the blend. The blend can be formed in a melt extruder or other conventional apparatus and the product can be suitably formed using known molding techniques, such as injection molding, or by extrusion.

The present invention will now be described in more detail with reference to the following non-limiting examples.

Example 1:

Four grades of TiO ₂ were obtained from the supplier. Their grades and properties are summarized in Table 1 below. Samples of the white composition were prepared as summarized in Table 2 below and tested for their flame retardancy and melt viscosity. The composition contained the following additives: release agent (pentaerythritol tetrastearate, commercially available as PETS G from Faci (> 90% esterification)); Phosphite stabilizers (tris (2,4-di-t-butylphenylphosphite, commercially available as IRGAFOS 168 from Ciba); hindered phenol stabilizers (octadecyl-3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate, commercially available as IRGANOX 1076 from Ciba); tradename NcendX P-30 (bisphenol A bis (diphenylphosphate)) or BPADP (commercially available from Albemarle) Drip retardant comprising T-SAN (50% by weight of polystyrene acrylonitrile and 50% by weight of poly (tetrafluoroethylene) obtained from General Electric Plastics Europe) Encapsulated poly (tetrafluoroethylene)).

In order to prepare the sample, polycarbonate pellets of bisphenol-A polycarbonate prepared by a melting process having a melt flow rate (MVR ℃ 300 ° C., 1.2 kg) of 23.5-28.5 g / cm 3 and a target value of 26.0 g / cm 3 were prepared in 5.1. Werner by mixing with pellets of bisphenol-A polycarbonate prepared by a melting process having a melt flow rate (MVR ＠ 300 ° C., 1.2 kg) (introduced through a powder feeder) of −6.9 g / cm 3 and a target value of 6.0 g / cm 3 Formulated in accordance with ISO294 on ENGEL injection molding machines using Axxicon ISO Manufactured (AIM) mold system for compounding on Werner & Pfleiderer idle twin screw extruder (25 mm screw) and subsequently to produce UL bar specimens It was. The resulting composition was tested according to the UL94 standard for Vertical Combustion Test V-0 at 1.6 mm. p (FTP) is the first time passability in the UL94 test. The results are shown in Table 3 below.

As apparent from the above results, the composition without colorant (NC) or with black pigment (BK) has a p (FTP) V0＠1.6 mm of 0.9 or more (90% or more probability of passing this test). Formulations containing no TiO ₂ had a reasonable possibility to pass the test. Melt viscosity was similar for each material to be tested.

This example illustrates the unexpected problems that occur when producing a white or lightly colored product using TiO ₂ in such a composition.

Example 2:

As indicated in Table 4 below, formulations were prepared by varying the amount of polycarbonate-siloxane copolymer from 12% to 20% using Tioxide R-FC5 ^™ (TiO ₂ Sample 1).

Flame retardancy was tested on these samples and 12% samples containing no (natural) colorants or containing black colorants. As shown in Table 5 below, only Lexan-ST (polycarbonate / polydie having a siloxane content of at least 20% by weight based on the total weight of the copolymer and a block length of 50 units of poly (diorganosiloxane) At least 0.9 p (FTP) × 1.6 mm was achieved only in TiO ₂ -containing samples with at least 1% TiO ₂ , with a level of 20% methylsiloxane (PC / PDMS) copolymer). Figure 1 shows the relationship between p (FTP) and% TiO ₂ in this experiment. As will be appreciated, as TiO ₂ increases, the p (FTP) value decreases.

Example 3:

The theoretical model with% polycarbonate-siloxane level = 14.5-21% (PC / ST ratio = 5.5-3.5) is designed with a polycarbonate-siloxane content of approximately 18% in a composition having a p (FTP) of at least 0.9. It was shown to be optimal in space. Thus, samples containing 18% polycarbonate-siloxane copolymers were prepared using the method described in Example 1, as indicated in Table 6 below. In addition to the components listed in Table 6 below, these compositions contained less than 0.01% by weight of colorant components in total. Colorants used in the formulation to obtain differently colored products include MONARCH 800, BAYFERROX 180 MPL, VERDE HELIOGEN K8730, AMARILLO SICOTAN K2001 FG, VERDE OXIDO DE CROMO, Pigment Yellow 119, AZUL SICOPAL K6310 and Ultramarine Ultramarine blue was included. The flame retardancy test results of these samples are described in Table 7 below.

Bulk polycarbonate-containing resin components; An amount of polycarbonate-siloxane copolymer sufficient to provide at least 3% by weight of siloxane of the total weight of the composition; And a colorant composition comprising titanium dioxide having an organic coating, such as a coating comprising polysiloxane, wherein the amount of titanium dioxide is 1 to 2.5% by weight, preferably 1 to 2.0% by weight, more preferably of the total weight of the composition. Preferably from 1 to 1.5% by weight), both light color and good flame retardancy. Such compositions can be used to produce shaped articles, especially those with thin wall regions that achieve a V0 UL fire rating at the first thickness.

Claims (8)

(a) a bulk resin component comprising a polycarbonate resin; (b) a polycarbonate-siloxane copolymer having a siloxane content in an amount sufficient to provide at least 3% by weight of siloxane of the total weight of the composition; And (c) a colorant composition comprising titanium dioxide, preferably having an organic coating comprising organosiloxane or trimethylolpropanol, wherein the amount of titanium dioxide is from 1 to 2.5% by weight of the total weight of the composition Composition. The method of claim 1, (a) said bulk resin component comprises at least 50% of the composition; (b) said bulk resin component further comprises an engineering thermoplastic, preferably styrene acrylonitrile copolymer or polymethyl (methacrylate); (c) the colorant composition comprises 1 to 1.5 weight percent of the total weight of the composition; (d) the organic coating comprises organosiloxane or trimethylolpropanol; or (e) A composition having at least one of the features wherein the amount of titanium dioxide is 1 to 1.5% by weight of the total weight of the composition. The method according to claim 1 or 2, (a) a rubbery impact modifier; (b) antidrip agents; Or (c) at least one of a flame retardant other than the polycarbonate-siloxane copolymer. The method of claim 3, wherein (a) The rubber-like impact modifier may be acrylic rubber, ASA rubber, diene rubber, organosiloxane rubber, EPDM rubber, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS ) Selected from the group consisting of rubber, ABS rubber, MBS rubber and glycidyl ester impact modifiers, and mixtures thereof; (b) the rubbery impact modifier is present in an amount from 1 to 30 weight percent; (c) the anti-drip agent is styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene; or (d) at least one of the features wherein the flame retardant is a phosphate flame retardant, preferably bisphenol A tetraphenyl diphosphate, or a perfluoroalkane sulfonate such as a sulfonate, preferably potassium perfluorobutane sulfonate. Having a composition. A composition made from the composition of any one of claims 1 to 4 having at least one wall thickness of at least a first thickness, wherein the molding composition is made to achieve a V0 UL fire rating at said first thickness. An article formed from the molding composition according to claim 1 wherein the amount of carbonate-siloxane copolymer is selected. The method of claim 5, An article having a first thickness of 1.6 mm. Forming a blend as defined in any of claims 1-4; And forming a product from the blend. Bulk resin component containing polycarbonate; Polycarbonate-siloxane copolymers; And a flame retardant of a lightly colored composition comprising a colorant composition comprising titanium dioxide, (a) using the polycarbonate-siloxane copolymer in an amount sufficient to provide at least 3% by weight of siloxane of the total weight of the composition; And (b) selecting titanium dioxide having an organic coating comprising polyorganosiloxane, trimethylolpropanol or mixtures thereof as titanium dioxide.

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