MXPA99011328A - Liquid crystalline polyester compositions containing carbon black - Google Patents

Abstract

Disclosed are liquid crystalline polyester molding compositions which are capable of being molded into an article having a thickness of less than 1.5 mm and a flammability classification of 94V-O as determined by the UL-94 20 mm Vertical Burning Test (ASTM D 3801) which are comprised of (i) certain all-aromatic, liquid crystal polyester consisting essentially of terephthalic acid residues, 2,6-naphthalenedicarboxylic acid residues, hydroquinone residues, and p-hydroxybenzoic acid residues;and (ii) about 0.1 to 10 weight percent, based on the total weight of the liquid crystalline polyester molding composition, carbon black. Theses liquid crystalline polyester molding compositions also may contain glass fiber. The disclosed molding compositions are particularly useful for manufacturing circuit boards and electrical connectors for use in various electronic devices.

Description

LIQUID CRYSTALLINE POLYESTER COMPOSITIONS CONTAINING BLACK CARBON DESCRIPTION OF THE INVENTION This application claims the benefit of US Provisional Application Serial No. 60 / 048,830 filed on June 6, 1997. This invention pertains to novel liquid crystalline polyester derivative compositions from terephthalic acid, 2,6-naphthalenedicarboxylic acid, hydroquinone and p-hydroxybenzoic acid containing about 0.1 to 10 weight percent carbon black. These new compositions can be molded into thin articles that exhibit a flammability rating of 94V-0 as determined by the "Flammability UL-94" test.The liquid crystalline polyester compositions also possess excellent mechanical properties, temperature resistance and Flame Resistance The compositions are especially useful when formed in composite with glass fibers and injection molded into thin articles useful as supports for circuit boards and / or electrical connectors for electrical / electronic applications such as in computers. Liquid crystalline polyesters (LCP) - are unique among polymers because they have high tensile, flexural and temperature resistance properties that are highly desirable for high performance applications, such as in structural applications and in electrical applications and electronic Another property that is alt Amente Desirable for electrical and electronic applications is a high resistance to burning. This property is most often measured by the Flanderwriters Laboratory Flammability Test (UL-94). A classification of V-0, (which is the best possible classification for the test) is desired for electrical and electronic applications. Among the initial LCPs available were those derived from poly (ethylene terephthalate) and p-acetoxybenzoic acid. These LCPs have the disadvantages of relatively low temperature resistance and inadequate flammability characteristics. Subsequently, all the aromatic LCPs were developed and marketed. Typical of these aromatic LCPs are those described in US Pat. No. 4,169,933 and derived from "terephthalic acid, 2,6-naphthalenedicarboxylic acid, hydroquinone, and p-hydroxybenzoic acid." Relatively thin, for example, less than 1.5 mm, articles which have good tensile and flexural modulus properties and high thermal properties (thermal distortion temperature) are used as circuit boards in the electrical / electronic industry.For such electronic applications, it is important that those thin articles exhibit excellent burnout resistance , for example of a 94V-0 classification as determined by UL-94 20 mm Vertical Burgning Test (ASTM D3801) US Patent 5,124,397 discloses a resin composition for sliding movement comprising (a) certain thermotropic liquid crystalline polyesters, and (b) from 10 to 70 weight percent spherical vitreous carbon. The compositions described also contain graphite, glass fiber or poly (tetrafluoroethylene). The flammability characteristics of the resin compositions are not mentioned in the patent. Japanese Published Patent Application JP 08-220,407 A discloses a light collection lens holder comprising a filled liquid flame retardant liquid crystal resin. PCT International Application WO 96/06888 describes LCP containing a small amount of low molecular weight polyethylene. The polyethylene acts as an internal lubricant or mold release, although it does not significantly increase the flammability of the LCP composition. Example 4C of this PCT patent document describes an LCP composition consisting of (i) 61.5% of an LCP containing residues of hydroquinone (9.6%), 4,4 '-biphenol (9.6%), terephthalic acid (13.5%) ), 2,6-naphthalenedicarboxylic acid (5.8%) and p-hydroxybenzoic acid (61.5%). (ii) 0.5% oxidized low pressure polyethylene, (iii) 23.3% glass fiber, (iv) 1.3% carbon black and (v) 13.3% talcum. The LCP compositions contemplated by this PCT patent document are intended for use in the manufacture of main parts in drive devices of copying machines, printers and video related equipment that requires good characteristics of mechanical strength and high tribology. The flammability characteristics of the LCP compositions are not mentioned. Japanese Published Patent Application JP 08-13,248 A discloses fire resistant polyester fibers prepared by mixing and spinning a masterbatch containing 5-40 weight percent carbon black and 60-95 weight percent of copolymer polyester based on poly (ethylene terephthalate) prepared by copolymerization of poly (ethylene terephthalate) with 5-20 mole percent of an isophthalic acid component and a matrix polymer consisting of poly (ethylene terephthalate) It does not contain carbon black. Liquid crystalline polyesters are not contemplated by this reference. Japanese Published Patent Application JP 07-196,894 A discloses a liquid crystalline resin composition consisting of 0.01-10 weight percent carbon black and a liquid crystalline polyesteramide or polyester forming an anisotropic melting phase. The liquid crystalline resin compositions also contain 0.5-60 parts by weight of a flame retardant organobromine compound per 100 parts of the liquid crystalline resin. JP 07-196,894 describes the flammability characteristics only for resin compositions containing an amount of flame retardant of an organobromine compound which suggests that the presence of such a flame retardant is essential up to an acceptable flammability rating. A selected class of liquid crystalline polyester compositions comprising (i) certain total aromatic liquid crystalline polyesters, (ii) carbon black, and optionally, (iii) glass fibers exhibiting excellent tensile properties and flexural moduli has been discovered. , high thermal properties and improved flammability characteristics (thermal distortion temperature) Compositions comprising components (i) and (ii) and glass fibers, for example 30 weight percent glass fibers exhibit a flammability rating of 94V-0 and reduced flame retardant times as determined by UL-94 20 mm Vertical Burning Test (ASTM D 3801) using an article having a thickness of less than 1.5 mm, preferably less than 1 mm, molded from the liquid crystalline polyester composition The liquid crystalline polyester component of the compositions of the present invention consists essentially of e of diacid residues consisting essentially of terephthalic acid (T), and residues of 2,6-naphthalenedicarboxylic acid (N); diol residues consisting of hydroquinone (HQ) residues; and p-hydroxybenzoic acid (PHB) residues. More specifically, the total aromatic liquid crystalline polyesters used in the present invention consist essentially of about 1.5 to 25 mole percent residues of terephthalic acid (T), from about 6.5 to 37 mole percent acid waste 2, 6-naphthalenedicarboxylic acid (N), about 16 £ to 42 percent mole of hydroquinone (HQ) residues, and about 17 to 67 mole percent of p-hydroxybenzoic acid (PHB) residues; wherein the total molar percentage of the residues T, N, HQ and PHB is equal to 100. Preferably, the molar ratio T: N is from about 10:90 to about 60:40, the moles of HQ are equal to Total moles of T and N, and the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to, or lower than 365 ° C. It has been found that the addition of carbon black to aromatic liquid crystalline polyesters improves the flammability characteristics of such polyesters by significantly reducing the post-flame times obtained in UL-94 20 mm Vertical Burning Test (ASTM D 3801). Research has shown that the addition of carbon black along with fiberglass to crystalline aromatic liquid polyesters reduces the time after the flame during the UL-94 test and can improve the flammability rating of polyester up to V-0 as was measured by UL-94 20 mm Vertical Burning Test. The excellent "classification of flammability that the liquid crystalline polyester compositions of the invention exhibit does not depend on the presence therein of any flame retardants such as bromide-containing flame retardants." Such bromide-containing compounds present both health and Corrosion and its use in molding compositions is usually not favored, Therefore, the polyester compositions of the present invention preferably lack essentially any flame retardants, particularly bromide-containing flame retardants. invention, in its broader aspects, provides novel liquid crystalline polyester molding composition comprising: i) a liquid crystalline polyester consisting essentially of about 1.5 to 25 mole percent of terephthalic acid (T) residues, about 6.5 to 37 mol percent of 2,6-naphthalic acid residues endicarboxylic (N), about 16 to 42 mole percent of hydroxyquinone (HQ) residues and about 17 to 67 mole percent of p-hydroxybenzoic acid (PHB) residues; where the total molar percentage of the residues T, N, HQ and PHB is equal to 100; and (ii) about 0.1 to 10 weight percent based on the total weight of the molding composition of liquid crystalline polyester, carbon black; provided that the articles have a thickness of less than 1.5 mm molded from the molding composition which also contains at least 20 weight percent glass fiber exhibiting a flammability rating of 94V-0 as determined by UL-94 20 'mm Vertical Burning Test (ASTM D 3801). A second embodiment of the invention is the liquid crystalline polyester molding composition defined above which also contains at least 20 weight percent glass fibers. The liquid crystalline polyester molding compositions of the present invention are particularly suitable for use in the manufacture of circuit boards in various electronic devices. The total aromatic liquid crystalline polyesters provided by the present invention consist essentially of diacid residues consisting essentially of residues of terephthalic acid (T) and residues of 2,6-naphthalene dicarboxylic acid (N); diol residues consisting of ^ hydroquinone (HQ) residues; and residues of p-hydroxybenzoic acid (PHB), more specifically, 1.5 to 25 mole percent residues of terephthalic acid (T), about 6.5 to 37 mole percent of 2, β-naphthalenedicarboxylic acid (N) residues , approximately 16 to 42 mole percent of hydroquinone (HQ) residues and approximately 17 to 67 mole percent of p-hydroxybenzoic acid (PHB) residues; wherein the total molar percentage of the residues T, N, HQ and PHB is equal to _100. Preferably, the molar ratio T: N is from about 10:90 to about 60:40, the moles of HQ are equal to total moles of T and N, and the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to, or less than about 375 ° C, more preferably less than about 365 ° C. These liquid crystalline polyesters can be prepared by methods well known to those skilled in the art, for example, by heating terephthalic acid, 2,6-naphthalenedicarboxylic acid, and acylated derivatives of hydroquinone and p-hydroxybenzoic acid with or without a catalyst for forming the LCP and a volatile carboxylic acid Examples of possible acylated derivatives of hydroquinone and p-hydroxybenzoic acid include hydroquinone diacetate and p-acetoxy acid and p-propionyloxybenzoic acid dipropionate Alternatively, the compositions can be prepared by heating the terephthalic acid, 2,6-naphthalenedicarboxylic acid, hydroquinone and p-hydroxybenzoic acid in a reactor with an aliphatic acid anhydride, such as acetic or propionic anhydride, with or without a catalyst, to first carry out the acylation of the groups hydroxy and carry out after the polycondensation reaction as described above For those skilled in the art, a useful variation of this alternative method is the separate acylation of the hydroxy-containing monomers in a first reactor, transferring this product to a second reactor, adding the dicarboxylic acids, and carrying out the polycondensation reaction as described above. Likewise, the liquid crystalline polyesters of the invention can be prepared by first synthesizing a relatively low molecular weight polyester by one of the previously described methods to form a pre-polymer which can then be further polymerized to a high molecular weight by techniques of solid state polymerization well known to those skilled in the art. Likewise, a prepolymer of the polyesters of the invention can be prepared with or without a catalyst in an extruder and be further polymerized at a higher molecular weight by solid state polymerization techniques well known to those skilled in the art. The diacid residues can be derived from terephthalic acid and, 6-naphthalenedicarboxylic acid, diaryl esters thereof, for example diphenyl terephthalate and difernyl. 2, 6-naphthalenedicarboxylate and possibly acid chlorides thereof, although diacids are preferred. If the diaryl esters of the diacids are used, the phenolic hydroxyl groups of hydroquinone and p-hydroxybenzoic acid must be non-esterified. Catalysts suitable for use in the preparation of LCP include dialkyl tin oxide, diaryl tin oxide, titanium dioxide, titanium alkoxy silicates, titanium alkoxides, alkali metal and alkaline earth metal salts of carboxylic acids, gaseous acids such as Lewis acids, for example, BF, hydrogen halides, for example, HCl, and the like. The amount of catalyst normally used is about 50 to about 500 parts per million based on the total weight of the starting materials (minus the amount of any acyl anhydride used.) If a multi-stage synthesis process is used as described above, the catalyst can be added during the acylation or the polycondensation steps The use of about 100 to about 300 parts per million by weight of at least one alkali metal-containing catalyst is sufficient The liquid crystalline polyesters of the present invention have inherent viscosities (IV) in the range of about 4 to 10 dl / g, preferably about 5 to 8 dl / g, measured at 25 ° C in 60:40 in weight of pentafluorophenol / 1,2,4-trichlorobenzene a 0.1 g / 100 ml in a Schott Gerate viscometer, as will be apparent to those with experience in the art ^ liquid crystalline polyesters may contain smaller amounts, for example, of up to 10 mole percent of the polyester, of residues derived from other diacid and diol monomers such as isophthalic acid, 1,4-cyclohexanedicarboxylic acid and 4,4'-biphenol provided, although the Fundamental properties of the molding compositions of the invention are retained. Aromatic liquid crystalline polyesters consist only more preferably of residues of terephthalic acid, 2,6-naphthalenedicarboxylic acid, hydroquinone, and p-hydroxybenzoic acid. The liquid crystalline polyester molding compositions of the present invention contain from about 0.1 to 10, preferably about 0.5 to 5, percent by weight of carbon black, based on the total weight of the molding composition. Any carbon black that is finely divided is suitable for use in the molding compositions of the present invention. Suitable carbon blacks include, but are not limited to, Black Pearl 800 and Dusty Black Black 35 from Cabot Corporation. The particle size of the carbon blacks can vary from about 10 to 500 nanometers with a particle size range of about 100 to 200 nanometers which is preferred. Liquid crystalline polyester molding compositions more preferably contain about 1 to 3 weight percent carbon black. The carbon black can be added to the PCL by any means known to those skilled in the art, so long as the carbon black is well dispersed and does not adversely affect the mechanical properties of the composition. Examples of suitable dispersion methods include extrusion and addition of carbon black during the preparation of LCP. In the extrusion method, the LCP, carbon black and other optional additives such as glass fiber can be extruded as a physical mixture. Likewise, the LCP and one of the other ingredients can be pre-extruded and formed into pellets, physically mixed with the remaining and extruded ingredients. Alternatively, the LCP and the carbon black or the LCP and the glass fiber can be added to the extruder hopper and the other ingredient (carbon black or fiberglass) can be fed laterally into the extruder. Preferably, the LCP, the carbon black and the optional fiberglass are mixed in one operation so that production costs are kept at a minimum level. Another alternative is to pre-extrude a mixture of carbon black, for example from about 10 to 50 weight percent, into a suitable polymer, preferably the same liquid crystalline polyester, to form a masterbatch which is then mixed with additional LCP and fiberglass to prepare the desired mixture. The molding compositions comprise a narrow mixture of the total aromatic crystalline polyester, described above, the carbon black and the glass fibers constitute a second embodiment of the present invention. Normally, the polyester compositions will contain at least 20 weight percent, preferably about 25 to 40 weight percent glass fibers. The glass fibers useful in preparing the compositions of the invention include those having thicknesses (diameters) of about 9 to 15 microns and fiber lengths of about 0.8 to 26 mm. (approximately 1/32 to 1 inch). The glass fibers can be coated or uncoated.

The LCP / carbon black / fiberglass compositions of the present invention are especially useful for molding relatively thin articles, for example of a thickness of less than 1.5 mm, preferably less than 1 mm. The LCP / carbon black / fiberglass compositions and the molded articles can be prepared using the composition techniques described above and processes that are conventional in the composition and formation of synthetic polymer compositions. For example, one or more of the liquid crystalline polyesters defined herein may be compounded with carbon black and glass fiber in an extruder and converted to tablets. Liquid crystalline polyester, carbon black and glass fibers can be composed of 10 to 400 mm of twin-screw extruders that can be co-rotating or counter-rotating. The tablets of the LCP / carbon black / fiberglass compositions can be formed into molded articles by means of an injection molding machine. Suitable injection molding machines normally have a clamping force of 20 to about 500 tons. The liquid crystalline molding compositions of the invention may contain various additives and fillers such as antioxidants, titanium dioxide, flame retardants, and droplet suppressors, if desired. The articles molded from the compositions are useful for a variety of end uses that require a combination of good tensile, flexural, swelling and thermal resistance properties. Molded articles are especially useful for use in electronic applications such as injection molded circuit boards and electrical connectors that will withstand welding conditions. An essential requirement of such circuit boards is that a test rod having a thickness of 0.8 mm (0.03125 inches) exhibits a flammability rating or range of 94V-0 as determined by UL-94 20 mm Vertical Burning Test (ASTM) D 3801). The preparation of the liquid crystalline polyesters and the glass fiber containing compositions of the present invention are further illustrated by the following examples. In the examples, the inherent viscosities (I.V., dl / g) of the LCP are measured at 25 ° C in 60:40 pentafluorophenol / 1,2,4-trichlorobenzene at 0.1 g / 100 ml in a Schott Gerate viscometer. The samples are dissolved by stirring at room temperature. The melting points are determined using a Differential Scanning Calorimeter, Model 2920, using a Thermal Analyst 2200 control system with LNCA II accessory at a heating ratio of 20 ° C / minute. The composition of the liquid crystalline polyesters is determined by hydrolyzing approximately 100 mg of polyester in a magnetically stirred culture tube in 2 ml of deoxygenated dimethyl sulfoxide (dß) and 0.5 ml of 5 N deoxygenated NaOH in methanol (d4). The hydrolysis is carried out at 80 ° C. After hydrolysis, the tube is cooled slightly and then 5 ml of deoxygenated D20 containing a reference is added to dissolve all the solids. The solution is then added to an NMR tube and capped. The proton NMR spectral data is collected with a JEOL Delta 270 spectrometer operating at 270.05 MHz for observation of the potron nucleus. The LCP / carbon black / fiberglass compositions are prepared with Black Pearl 80O carbon black (Cabot Corporation) having an average particle size of 17 nm and Owens Corning OC492A glass fiber having a diameter of 11 microns and a length of 6.4 mm (1/4 inch) or Owens Corning OC408BC glass fiber that has a diameter of 14 microns and a length of 6.4 mm (1/4 inch) by composing and extruding from a 30-mm extruder Wener-Pfleiderer that has an L / D ratio of 32, 9 barrels and 6 zones. The LCP and carbon black are fed to the neck of the extruder and the fiberglass is fed downstream through the side feeder. A fixed temperature point of 335 ° C is used in the first half of the extruder to ensure complete melting of the LCP. A lower fixed point of 310 ° C is used in the downstream half of the extruder to improve the integrity of the extruded stream that is ground into approximately 3 mm (approximately 1/8 inch) tablets. The composite tablets are injection molded in test bars 13 mm x 125 mm x 0.8 mm in a Boy 50 Injection Molding Machine with a melting temperature of 335 ° C and a mold temperature of 90 ° C. The liquid crystalline polymer and the composite tablets are dried at 150 ° C overnight in a Conair dehumidifying dryer before each stage. The flammability of the 0.8 mm thick test bars is determined as specified by the UL-94 flammability test. EXAMPLE 1 AND COMPARATIVE EXAMPLE Cl A liquid crystalline polyester consisting of 8.6 mole percent residues of terephthalic acid, 20 mole percent residues of 2,6-naphthalenedicarboxylic acid, 28.6 mole percent hydroquinone residues and 42.8 mole percent percent of p-hydroxybenzoic acid residues and having IV of about 6.0 dl / g is prepared by melt polymerization processes from terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid. LCP is composed of Owens Corning OC492A glass fibers to prepare a liquid crystalline molding composition containing 30 weight percent glass fiber (Comparative Example C-1) The same LCP is composed of carbon black and fiberglass Owens Corning OC492A for obtaining a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30 percent by weight of fiberglass (Example 1). The test bars 13 mm x 125 mm x 0.8 mm "in thickness are prepared from molding compositions and the flammability characteristics are determined by the Flammability Test UL-94. The flammability rating of the bars of Example 1 is V-0/33 and (2) the bars of Comparative Example C-1 is-V-0/42 is determined by UL-94 20 mm Vertical Burning Test The values "33" and "42" refer to times after of the total flame (in seconds) for a set of 5 bars tested, that is, the sum of the times after the flame "(t + t2) for a set of 5 bars. The times ti + t2 are the times in seconds that a bar continues for after the flame once the flame source has been removed. "Tests for Flammability of Plastics Materials - UL 94", published on May 14, 1993, also defines times ti + t2. If the sum of the times after the flame ti + t2 for a set of 5 samples exceeds 50 seconds, the UL 94 classification can not be V-0. Example 1 and Comparative Example C-1 illustrate that carbon black significantly reduces the flammability, especially the post-flame times of a liquid crystalline polyester molding composition according to the present invention. EXAMPLES 2 AND "3 AND COMPARATIVE EXAMPLE C-2 A" liquid crystalline polyester consisting of 8.6 moles per "percent residues of terephthalic acid, 20 mole percent of 2,6-naphthalene dicarboxylic acid residues, 28.6 mole percent of waste of hydroquinone and 42.8 mol percent of p-hydroxybenzoic acid residues and having an IV of about 6.2 dl / g is prepared through terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid and is further polymerized by a solid state process The LCP is composed of Owens Corning OC408BC glass fiber to prepare a crystalline polyester molding composition -liquid containing 30 weight percent glass fibers (Comparative Example C-2). The same LCP is composed of carbon black and Owens Corning OC408Bc glass fiber to obtain the liquid crystalline polyester molding compositions containing 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber (Example 2) and 2.0 weight percent carbon black and 30 weight percent fiberglass (Example 3). The test bars 13 mm x 135 mm x 0.8 mm thick (1/2 inch x 5 inches x 1/32 inch thickness) were prepared from the three molding compositions and the mechanical properties and flammability characteristics (UL-94 Flammability Test) are determined. The flammability tests were carried out on bars of 13 mm x 125 mm x 0.8 mm. Tension tests were performed on bars of 19 mm x 216 mm x 3.2 in thickness (3/4 inch x 8.5 inches x 1/8 inch thickness). Bending tests were performed on 13 mm x 127 mm x 19 mm thick bars (1/2 in. X 5 in. X 1/8 in. Thick). The results are shown in Table I. The values given for the thermal distortion temperatures (HDT; ASTM D 648; at 18559.2 g / cm2 (264 pounds per square inch) are ° C; the values given for the tensile strength (ASTM D 638) are in g / cm2 (pounds per square inch); the values given for elongation at break (ASTM D 638) "are percentages; 7 _" "and the values given for Notched Izod (ASTM D 256; executed at 23 ° C) are in joules (feet-pounds per inch). These examples further illustrate that carbon black significantly reduces the time after the flame of the samples and has no deleterious effect on the critical mechanical properties of the LCP when it is composed of 30 weight percent glass fiber.

TABLE I Examples C-2 2 3 HDT 296 297 296 Resistance to tension 18,169 19,859 19,325 Elongation at break 1.5 1.7 1.8 Notched Izod 2.1 1.9 1.9 Classification UL-94 V2 / 42 VO / 32 VO / 36 Example C-2 of the molding composition received a V2 classification due to a of the five bars tested he drained and lit the cotton. The time after the flame for this composition was 42 seconds which is less than the time after the flame of 50 seconds allowed for a V-0 classification. EXAMPLE 4 AND COMPARATIVE EXAMPLE C-3 Liquid crystalline polyester consisting of 8.6 mole percent residues of terephthalic acid, 20 mole percent residues of 2,6-naphthalenedicarboxylic acid, 28.6 mole percent of hydroquinone residues and 42.8 mole percent of p-hydroxybenzoic acid residues and that has an IV of about 6.5 dl / g were prepared from terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid and additionally polymerized by solid state process. The LCP is composed of Owens Corning OC408BC glass fiber to prepare a liquid crystalline polyester molding composition containing 30 weight percent glass fiber (Comparative Example C-3). The same LCP is composed of Owens Corning OC40BC carbon black and glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber (Example 4). ). The test bars 13 mm x 125 mm x 0.8 mm thick were prepared from molding compositions and the flammability characteristics (UL-94 Flammability Test) were determined by two groups of five test bars for each molding composition. The test bars prepared from Comparative Example C-3 and its composition have flammability classifications of V-0/45 and V-0/47, considering that the test bars prepared from the composition of Example 4 have classifications of flammability of V-0/35 and V-0/38. EXAMPLE 5 A liquid crystalline polyester consisting of 8.6 mole percent residues of terephthalic acid, 20 mole percent of 2,6-naphthalenedicarboxylic acid residues, 28.6 mole percent of hydroquinone residues and 42.8 mole percent of acid waste p-hydroxybenzoic and having an IV of about 6.1 dl / g is prepared from terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid and further polymerized by solid state process. This LCP is composed of carbon black and Owens Corning OC408BC glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber. The test bars 13 mm x 125 mm x 0.8 mm thick were prepared from the molding composition and the flammability characteristics (UL-94 Flammability Test) were determined for two groups of five bars. Both groups of test bars have flammability ratings of V-0/40. EXAMPLE 6 A liquid crystalline polyester consisting of 8.6 mole percent residues of terephthalic acid, 20 mole percent residues of 2,6-naphthalenedicarboxylic acid, 28.6 mole percent of hydroquinone residues and 42.8 mole percent waste p-hydroxybenzoic acid and having an IV of about 6.0 dl / g is prepared from terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid and further polymerized by solid state process. This LCP is composed of carbon black and Owens Corning OC408BC glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber.

The test bars 13 mm x 125 mm x 0.8 mm thick were prepared from the molding composition and the flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars. Both groups of test bars have flammability ratings of V-0/37. EXAMPLE 7 AND COMPARATIVE EXAMPLE C-4 Liquid crystalline polyester consisting of 12.7 mole percent terephthalic acid residues, 20.7 moles per "percent" of 2,6-naphthalenedicarboxylic acid residues, 33.4 mole percent of hydroquinone residues and 33.2 mole percent of p-hydroxybenzoic acid residues and having an IV of about 6.8 dl / g and a point of melting of 332 ° C are prepared from melt polymerization of terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid.This LCP is composed in a Wener-Pfleiderer extruder in one case, with Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 30_ percent by weight glass fiber (composition of Comparative Example 4), and in a second case, with Black Pearl 800 carbon black (Cabot Corporation) and Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber (Composition of Example 7). The test bars 13 mm x 125 mm x 0.8 mm thick were prepared from molding compositions by injection molding on a Boy 50-S Injection Molding Machine and the flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars. The test bars prepared from the Composition of Example 7 have a total burn time of 27 seconds and a flammability rating of V-0 while the test bars prepared from Comparative Example 4 and their composition had a total burn time of 101 seconds and a classification and inflammability of Vl. EXAMPLE 8 AND COMPARATIVE EXAMPLE C-5 - A liquid crystalline polyester polymer consisting of 3.9 mole percent terephthalic acid residues, 15.4 mole percent 2-6 naphthalenedicarboxylic acid residues, 19.3 mole percent hydroquinone residues and 61.4 mole percent mole percent of p-hydroxybenzoic acid residues and having a 6.6 dl / g and a melting point of 322 ° C are prepared by melt polymerization of terephthalic acid, 2,6-naphthalene dicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid. This LCP is composed of a Wener-Pfleiderer extruder in one case with Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 30 weight percent glass fiber (Composition of Comparative Example 5) , and in a second case, with Black Pearl 800 carbon black (Cabot Corporation) and Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 percent by weight of carbon black and 30% by weight. percent by weight of glass fiber (Composition of Example 8). The test bars 13 mm x 125 mm x 0.8 mm thick were prepared from molding compositions by injection molding in a Boy 50-S Injection Molding Machine and the flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars. The test rods prepared from the Composition of Example 8 have a total burn time of 39 seconds and a flammability rating of V-0 considering that the rods can be prepared from the composition of Comparative Example 5 had a time of total burnt of 83 seconds and a flammability rating of Vl. EXAMPLE 9 AND COMPARATIVE EXAMPLE C-6 A liquid crystalline polyester consisting of 10.3 mole percent terephthalic acid residues, 25.2 mole percent 2,6-naphthalenedicarboxylic acid residues, 35.5 mole percent hydroquinone residues and 29.0 mole percent of p-hydroxybenzoic acid residues and that has an IV 5.8 dl / g and a melting point of 325 ° C are prepared by melt polymerization of terephthalic acid, 2,6-naphthalenedicarboxylic acid, p-diacetoxybenzene, and p-acetoxybenzoic acid. This LCP is composed in a Wener-Pfleiderer extruder in one case, with Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 30 weight percent glass fiber (Example Composition Comparative 6), and in a second case, with Black Pearl 800 carbon black (Cabot Corporation) and Owens Corning OC-492A glass fiber to obtain a liquid crystalline polyester molding composition containing 1.0 weight percent black carbon and 30 weight percent fiberglass (Composition of Example 9). The test bars 13 mm x 125 mm x ~ 0.8 mm thick were prepared from of molding compositions by injection molding in a Boy 50-S Injection Molding Machine and flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars. The test bars prepared from the Composition of Example 9 have a total burn time of 42 seconds and a flammability rating of V-0 considering that the test bars can be prepared from the composition of Comparative Example 6 had a total burn time of 90 seconds and a flammability rating of Vl. EXAMPLE 10 AND COMPARATIVE EXAMPLE C-7 The procedures described in Examples 7-9 were repeated to prepare compositions comprising a liquid crystalline polyester consisting of 14.3 mole percent terephthalic acid residues., 14.3 mole percent of 2,6-naphthalenedicarboxylic acid residues, 28.6 percent of hydroquinone residues and 42.8 mole percent of p-hydroxybenzoic acid residues containing (1) 30 percent by weight of PPG 3540 glass fiber (Composition of Comparative Example 7) and (2) 1.0 percent by weight of carbon black and 30 percent by weight of glass fiber PPG 3540 (Composition of Example 10). Flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars 13 mm x 125 mm x 0.8 mm thick prepared from the compositions. The test bars prepared from the Composition of Example 10 have a total burn time of 27 seconds and a flammability rating of V-0 considering that the test bars can be prepared from the composition of Comparative Example 7 had a total burn time of 101 seconds and a flammability rating of Vl. EXAMPLE 11 AND COMPARATIVE EXAMPLE C-8 The procedures described in Examples 7-9 were repeated to prepare compositions comprising a liquid crystalline polyester consisting of 8.6 mole percent residues of terephthalic acid, 20.0 mole percent acid residues 2 , 6-naphthalenedicarboxylic acid, 28.6 percent hydroquinone residues and 42.8 mole percent p-hydroxybenzoic acid residues containing (1) 30 weight percent PPG 3540 glass fiber (Composition of Comparative Example 8) and (2) ) 1.0 weight percent carbon black and 30 weight percent PPG 3540 glass fiber (Composition of Example 11). Flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars 13 mm x 125 mm x 0.8 mm thick prepared from the compositions. The test bars prepared from the Composition of Example 11 have a total burn time of 43 seconds and a flammability rating of V-0 considering that the test bars can be prepared from the composition of Comparative Example 8 had a total burn time of 87 seconds and a flammability rating of Vl. EXAMPLE 12 AND COMPARATIVE EXAMPLE C-9 The procedures described in Examples 7-9 were repeated to prepare compositions comprising a liquid crystalline polyester consisting of 3.8 mole percent of terephthalic acid residues, 19.2 mole percent of acid residues. , 6-naphthalenedicarboxylic acid, 23.0 percent hydroquinone residues, and 54.0 mole percent p-hydroxybenzoic acid residues containing (1) 30 weight percent glass fiber PPG 3540 (Composition of Comparative Example 9) and (2) ) 1.0 weight percent carbon black and 30 weight percent PPG 3540 glass fiber (Composition of Example 12). The flammability characteristics (UL-94 Flammability Test) were determined for two groups of five test bars 13 mm x 125 mm x 0.8 mm thick prepared from the compositions. The test bars prepared from the composition of Example 12 have a total burn time of 39 seconds and a flammability rating of V-0 considering that the test bars can be prepared from the composition of Comparative Example 9 had a total burn time of 83 seconds and a flammability rating of Vl. It has been described in detail in the invention with particular reference to the preferred embodiments thereof, although it will be understood that variations and modifications will be made within the spirit and scope of the invention.

Claims (10)

1. CLAIMS 1. A liquid crystalline polyester molding composition comprising: (i) a total aromatic liquid crystalline polyester consisting of 1.5 to 25 mole percent terephthalic acid (T) residues, 6.5 to 37 mole percent acid waste 2, 6-naphthalenedicarboxylic acid (N), 16 to 42 mole percent residue (HQ), and 17 to 67 percent p-hydroxybenzoic acid (PHB) residue; wherein the total molar percentage of the residues T, N, HQ and PHB is equal to 100 and the liquid crystalline polyester has an inherent viscosity in the range of 4 to __ 10 dl / g measured at 25 ° in 60:40 by weight of pentafluorophenol / 1, 2,4-thromchlorobenzene; and (ii) from 0.1 to 10 weight percent, based on the total weight of the liquid crystalline polyester molding composition, of carbon black; provided that the articles have a thickness of less than 1.5 mm molded from the molding composition which also contains at least 20 weight percent glass fiber that exhibit a flammability rating of 94V-0 as determined through the UL-94-20 mm Vertical Burning Test (ASTM D 3801).
2. 2. The molding composition according to claim 1, characterized in that the molar ratio T: N is 10:90 to 60:40, the moles of HQ are equal to the total moles of T and N, the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to or less than 375 ° C and the amount of carbon black present is 0.5 to 5 weight percent, based on the total weight of the molding composition of liquid crystalline polyester.
3. 3. The composition according to claim 1, characterized in that the amount of carbon black present is 0.5 to 5 weight percent, based on the total weight of the liquid crystalline polyester molding composition, and the composition contains at least 20 weight percent, based on the total weight of the liquid crystalline polyester molding composition, of glass fiber.
4. 4. The molding composition according to claim 3, characterized in that the molar ratio T: N is 10:90 to 60:40, the moles of HQ are equal to the total moles of T and N, the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to, or less than 375 ° C, and the amount of glass fiber present is from 25 to 40 weight percent based on the total weight of the molding composition of liquid crystalline polyester.
5. 5. The molding composition according to claim 4, characterized in that the molar ratio T: N is 10:90 to 60:40, the moles of HQ are equal to the total moles of T and N, the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to, or less than 375 ° C, the amount of carbon black present is 1 to 3 weight percent, based on the total weight of the molding composition of liquid crystalline polyester, the amount of glass fiber present is 25 to 40 weight percent, based on the total weight of the liquid crystalline polyester molding composition, and the glass fibers have thicknesses (diameters) of 9 to 15 microns and fiber lengths from 0.8 to 26 mm.
6. 6. A molded article having a thickness of less than 1.5 mm and a flammability rating of 94V-0 as determined by the Vertical Burning Test (ASTM D 3801), comprised of: (i) a total aromatic liquid crystalline polyester consisting of 1.5 to 25 mole percent residues of terephthalic acid (T), 6.5 to 37 mole percent residues of 2,6-naphthalenedicarboxylic acid (N), 16 to 42 mole percent of hydroquinone (HQ) residues , and 17 to 67 mole percent of p-hydroxybenzoic acid (PHB) residues; wherein the total molar percentage of the residues T, N, HQ and PHB is equal to 100 and the liquid crystalline polyester has an inherent viscosity in the range of 4 to 10 dl / g measured at 25 ° in 60:40 in weight of pentafluorophenol / 1, 2, 4-thyrochlorobenzene; and (ii) from 0.1 to 10 weight percent, based on the total weight of the liquid crystalline polyester molding composition, of carbon black.
7. The molded article according to claim 6, characterized in that the molar ratio T: N is 10:90 to 60:40 the moles of HQ are equal to the total moles of T and N, the liquid crystalline polyesters have points of fusion determined by differential scanning calorimetry (DSC) equal to, or less than 375 ° C and the amount of carbon black present is 0.5 to 5 weight percent, based on the total weight of the crystalline polyester molding composition liquid.
8. The molded article according to claim 6, characterized in that it contains at least 20 weight percent, based on the total weight of the glass fiber molded article.
9. 9. The molded article according to claim 8, characterized in that the molar ratio T: N is 10:90 to 60:40, the moles of HQ are equal to the "total moles of T and N, the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to, or less than 375 ° C, the amount of carbon black present is 0.5 to 5 weight percent based on the total weight of the molded article and the amount of The present fiberglass is 25 to 40 weight percent, based on the total weight of the molded article
10. 10. The molded article according to claim 8, characterized in that the molar ratio T: N is 20:80 to 45: 55, the moles of HQ are equal to the total moles of T and N, the liquid crystalline polyesters have melting points determined by differential scanning calorimetry (DSC) equal to or less than 355 ° C, the amount of black of present carbon is 1 to 3 weight percent in bas For the total weight of the molded article, the amount of glass fiber present is 25 to 40 weight percent, based on the total weight of the molded article, and the glass fibers have thicknesses (diameters) of 9 to 15 microns. and the fiber lengths from 0.8 to 26 mm.