HK1106180A - Pelletized brominated anionic styrenic polymers and their preparation and use - Google Patents

Description

Pelletized brominated anionic styrenic polymers and their preparation and use

Technical Field

Brominated anionic styrenic polymers are very good flame retardants and are described in U.S. patent nos. 5,677,390; 5,686,538, respectively; 5,767,203, respectively; 5,852,131, respectively; 5,916,978 and 6,207,765 have disclosed very good methods for preparing the polymeric flame retardants.

Brominated anionic styrenic polymers are characterized by a tendency to form a large number of small particles and powders during granulation, such as brominated anionic polystyrene. It is apparent that when the particles are formed, they are easily broken and separated into small particles and fine powders, generally called "fines", unless they are bonded together by an additional binder or the like. Because of this feature, conventional pelletizing processes of various types are not suitable for making brominated anionic styrenic polymers substantially free of fines. It is also clear that the presence of fine powders in such products not only detracts from the appearance of the granulated product, but is also undesirable to the consumer.

In certain thermoplastic polymers, binders or other additional materials are used to ensure the integrity of the pelletized flame retardant in order to effectively utilize the brominated anionic styrenic polymer as a flame retardant, which is also undesirable to consumers. Thus, there is a need for a process for preparing undoped pelletized brominated anionic styrenic polymers that does not form undesirable fines during manufacture and packaging.

Brief summary of the invention

Brominated anionic styrenic polymers, in accordance with the present invention, can now be prepared and packaged in an undoped, pelletized form substantially free of fines. More preferred embodiments of the present invention enable economically beneficial results due to the relatively small amount of fines produced during operation. In fact, in a preferred embodiment of the invention, small amounts of dry fines may be formed which can be recycled in operation without incurring great expense and difficulty.

Thus, in accordance with one of the embodiments of the present invention, there are provided particles of undoped brominated anionic styrenic polymer having a bromine content of at least about 50 wt%, and wherein at least about 70 wt% (preferably at least about 75 wt%) of the particles are retained on a U.S. standard sieve No. 40 and no more than about 30 wt% (preferably no more than about 25 wt%) of the particles are retained on a U.S. standard sieve No. 5. In a preferred embodiment, the pelletized anionic styrenic polymer is a brominated anionic polystyrene having a bromine content of at least about 67 wt%, such as in the range of about 67 to about 71 wt%. Also preferred are pelletized brominated anionic styrenic polymers having a melt flow index (ASTM D1238-99) of at least about 4g/10min at 220 ℃ and 2.16kg, and more preferably at least about 5g/10min at 220 ℃ and 2.16 kg. If properly handled, the granules are substantially free of fines when prepared and packaged, i.e., granules that pass through a U.S. standard No. 40 sieve.

Another embodiment of this invention is a process for preparing particulate undoped brominated anionic styrenic polymer which comprises:

A) forming a ribbon of molten undoped brominated anionic styrenic polymer;

B) cooling the noodles and causing the noodles to break into particles thereon by flowing downwardly directed pressurized air onto a foraminous conveyor belt; and is

C) The pellets fall down into a classifier that removes fines from the pellets.

The term "undoped" means that no additional components, such as binders (e.g., waxes or other polymeric or oligomeric materials), inorganic salts, etc., have been added to the brominated anionic styrenic polymer prior to or during the aforementioned method of preparing the particles. In contrast, brominated anionic styrenic polymers contain only residual impurities remaining in the brominated polymer after it is prepared.

These and other embodiments of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.

Drawings

Figure 1 is a schematic front view of a mechanical system which has been found to be effective in preparing the particulate brominated anionic styrenic polymer of the present invention in accordance with the process of the present invention.

Fig. 2 is a schematic plan view of the system of fig. 1, simplified with components 10 and 12 omitted.

Further detailed description of the invention

Brominated anionic styrenic polymers

The polymer converted to particulate form according to the present invention is one or more of the blended brominated anionic styrenic polymers, namely: (i) at least one anionically produced brominated styrenic homopolymer, or (ii) at least one anionically produced brominated copolymer having two or more styrenic monomers, or (iii) both (i) and (ii). The bromine content of the polymer is at least about 50 weight percent. Preferred brominated anionic styrenic polymers, particularly brominated anionic polystyrenes, have a bromine content of at least about 60 wt%, more preferred brominated anionic styrenic polymers, particularly brominated anionic polystyrenes, have a bromine content of at least about 64 wt%, and particularly preferred brominated anionic styrenic polymers, particularly brominated anionic polystyrenes, have a bromine content in the range of about 67 wt% to about 69 wt%. Brominated anionic styrenic polymers such as brominated anionic polystyrene rarely have a bromine content in excess of about 71 weight percent. The brominated polystyrenic polymer generally has a melt flow index of at least about 3g/10min, preferably at least about 4g/10min, and more preferably at least about 5g/10min as measured by ASTM D1238-99 test procedure conducted at 220 ℃ and 2.16 kg. Typically, the melt flow index will range from about 3g/10min to about 40g/10min, and preferably from about 4g/10min to about 35g/10min, with the most preferred brominated styrenic polymers used in the practice of the present invention having a melt flow index in the range of from about 5g/10min to about 30g/10min under the conditions tested. In this regard, these polymers may not "melt" upon reaching the melting point temperature (at which they suddenly change from a solid to a liquid state), but rather they tend to become amorphous, i.e.: upon heating, they become progressively softer and progressively softer as the temperature increases, and tend to take on the characteristics of a liquid state into which other substances can be dispersed by using conventional mixing or blending processes.

In all embodiments of the invention, the most preferred brominated anionic styrenic polymer used to form the particles of the invention is undoped brominated anionic polystyrene.

Anionic polystyrene-based polymer, brominated to form a brominated anionic polystyrene-based polymer pelletized according to the present invention, is one or more anionic homopolymers and/or anionic copolymers of at least one vinyl aromatic hydrocarbon-based monomer. Preferred vinyl aromatic hydrocarbon monomers have the following general formula:

H₂C＝CR-Ar

wherein R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Ar is an aromatic group (including an alkyl ring-substituted aromatic group) having 6 to 10 carbon atoms, examples of the monomer are: styrene, alpha-methylstyrene, o-methylstyrene, m-methylstyrene, p-ethylstyrene, isopropenyltoluene, vinylnaphthalene, isopropenylnaphthalene, vinylbiphenyl, vinylanthracene, dimethylstyrene and tert-butylstyrene. Polystyrene is the preferred reactant. When the brominated anionic styrenic polymer is prepared by brominating an anionic copolymer of two or more vinyl aromatic hydrocarbon-based monomers, it is preferred that styrene be one of the monomers and that styrene contain at least 50 weight percent, and preferably at least about 80 weight percent, of copolymerizable vinyl aromatic hydrocarbon-based monomers. It should be noted that the terms "brominated anionic styrenic polymer" and "brominated anionic polystyrene" as used herein refer to anionic styrenic polymers that have previously existed by bromination such as: brominated anionic polymers made from anionic polystyrene or anionic copolymers of styrene or at least one other vinyl aromatic hydrocarbon-based monomer, to distinguish them from oligomers or polymers made by oligomerization or polymerization of one or more brominated styrenic monomers. The properties of the latter oligomers or polymers are significantly different from brominated anionic polystyrene in many respects. Also, the monomers or polymers associated with the terms "vinyl aromatic" and "styrenic" are used interchangeably herein.

The pendant aromatic groups comprising the anionic styrenic polymer may be alkyl substituted or substituted with bromine or chlorine atoms, but in most cases this substitution is not made.Generally, the anionic styrenic polymer used to prepare the brominated anionic styrenic polymer used in the practice of this invention has a weight average molecular weight (M)_w) Is in the range of about 2000 to about 50,000, and the polydispersity is in the range of 1 to about 10. Preferred brominated anionic styrenic polymers useful in the practice of this invention are prepared from anionic styrenic polymers having a weight average molecular weight (M)_w) Is in the range of about 3000 to about 10,000 and the polydispersity is in the range of 1 to about 4, and most preferably the ranges are about 3500 to about 4500, and 1 to about 4, respectively. M_wAnd polydispersity values are based on Gel Permeation Chromatography (GPC) techniques as will be described later.

Preparation methods for preparing anionic styrenic polymers such as anionic polystyrene are known in the art and reported in the literature. See, for example: U.S. patent nos. 3,812,088; 4,200,713, respectively; 4,442,273, respectively; 4,883,846, respectively; 5,391,655, respectively; 5,717,040, respectively; and 5,902,865, the disclosures of which are incorporated herein by reference. A particularly preferred method is disclosed in commonly owned U.S. Pat. No. 6,657,028, published on 9/2/2003, the disclosure of which is incorporated herein by reference.

Bromination processes that can be used to prepare brominated anionic styrenic polymers are disclosed in U.S. patent nos.: 5,677,390, respectively; 5,686,538, respectively; 5,767,203, respectively; 5,852,131, respectively; 5,916,978, respectively; and 6,207,765, the disclosures of which are incorporated herein by reference.

Preferred general properties of the brominated anionic polystyrene used to prepare the particles of the present invention include the following:

appearance/morphology-white powder

Bromine content-67 to 71 wt%

Melt flow index (220 ℃, 2.16kg) -4 to 35g/10min

Tg(℃)-162

Specific gravity (@23 ℃) -2.2

TGA (TA instruments model 2950, 10)At a temperature of N/min₂Lower)

1% weight loss, deg.C-342

5% weight loss, DEG C-360

10% weight loss, deg.C-368

50% weight loss, deg.C-393

90% weight loss, DEG C-423

Any reliable analytical method, as reported in the literature, can be used in determining the assay or property if deemed necessary or desirable. In any case of uncertainty or divergence, the following method is recommended:

1) bromine content-determination of the total bromine content of brominated anionic styrenic polymers is readily accomplished by using conventional X-Ray fluorescence techniques, due to their good or at least satisfactory solubility in solvents such as Tetrahydrofuran (THF). The samples analyzed were diluted samples, such as 0.1. + -. 0.05g of brominated anionic polystyrene in 60mL THF. The XRF spectrometer may be a Phillips PW1480 spectrometer. A standard solution of bromobenzene in THF was used as calibration standard.

2) Melt flow index-determination of the melt flow index of brominated anionic styrenic polymers using the method and test set-up of ASTM test method D1238-99. The extrusion plastometer was operated at 220 ℃ and 2.16kg applied pressure. The samples used in the tests contained 14 to 16 grams of brominated anionic polystyrene.

3) M of weight average molecular weight and polydispersity-anionic styrenic polymers_wValues were obtained by GPC using a Waters model 510 HPLC pump and as detector, a Waters refractive index detector, model 410, and Precision detectors, model PD2000, or equipment equivalent thereto. The columns were Waters's. mu. polystyrene type cross-linked copolymers, 500 Å, 10,000 Å and 100,000 Å. The autosampler was Shimadzu, model Sil 9A. PolystyreneAlkene standard sample (M)_w185,000) are periodically used to verify the accuracy of the light scatter values. The solvent was tetrahydrofuran, HPLC grade. The test method used required dissolving 0.015-0.020g of the sample in 10ml of THF, filtering an aliquot of the solution, and injecting 50. mu.L into the column. The separation was analyzed using software supplied by Precision detectors for a PD2000 light scatter detector. The results obtained with this instrument are weight average molecular weight and also number average molecular weight. Thus, the polydispersity value is obtained by dividing the weight average molecular weight by the number average molecular weight.

Preparation of granules

As noted above, the pelletized brominated anionic styrenic of the present invention can be prepared by a process comprising:

A) forming a ribbon of molten undoped brominated anionic styrenic polymer;

B) cooling the noodles while on the moving foraminous conveyor belt and causing at least a portion of the noodles to be broken up into particles by the downwardly directed pressurized air; and is

C) The particles leave the conveyor belt and fall into a classifier, where optionally at least part of the further fragments are broken up into particles, and in the classifier fines are removed from the particles formed in B), or optionally in C).

In carrying out step a) above, various commercially available machines can be successfully used to form molten or softened noodles of brominated anionic styrenic. For example, a Buss Ko-kneader (Coperion GmbH) or a co-rotating intermeshing twin screw extruder using Coperion GmbH, Berstoff, Century, Leistritz or JSW Japan Steel Works may be used. The machine is operated at a temperature in the appropriate range so that the brominated anionic styrenic polymer, if not molten, is at least highly flexible. The temperature range employed will vary somewhat depending upon the composition of the brominated anionic styrenic polymer to be processed. Thus, for brominated anionic polystyrene having the above properties, such as SAYTEX ® HP 3010, a temperature range of 220-240 ℃ has been found to be suitable.

In step B), the extrudate from the machine passes through a die plate and the resulting continuous strand falls onto a moving foraminous conveyor belt. Conveyor belt systems have a vacuum apparatus disposed below the porous bed that continuously draws air down onto the strips on the belt and down through the holes in the belt. Above the conveyor belt are located water sprays for cooling the hot polymer strands and downwardly located air blowers which provide sufficient capacity to cool the strands so that at least some of the strands on the belt are typically partially broken. If present, the unbroken strips, which are not supported as they leave the conveyor belt, are generally at least partially broken by gravity as they are pulled off the end of the belt.

In step C), the material on the belt and possibly all the material of the preceding conveyor belt that has escaped from the end of the conveyor belt falls into a classifier, which separates the particles and the fine powder from each other. The fall onto the classifier may also cause partial fragmentation to occur. The classifier may comprise, for example, a substantially horizontally disposed screen vibrating longitudinally back and forth. A particularly suitable machine of this type is a vibratory classifier such as that available from WitteCompany, inc.

In the general operation of step A), the conveyor belt used is about 14 feet (about 4.27 meters) long and operates at a speed in the range of about 100 to about 200ft/min (about 60.96 m/min). The pressurised air and water used to spray the noodles is typically at room temperature, but may be heated if desired in order to reduce thermal shock. The distance between the screens falling from the end of the conveyor belt into the classifier ranged from about 18 to about 36 feet (about 45.7 to about 91.4 cm).

In proper execution of the granulation process of the present invention, it is possible to produce a product having no more than about 5 wt%, preferably no more than about 3 wt%, more preferably no more than about 1 wt% of fines or dust passing through a U.S. standard No. 40 sieve. The process of the invention is therefore very efficient, collecting the fines only in small amounts and preferably recycling it back to step a) of the entire granulation operation.

The above operation of the present invention can be further explained by referring to the drawings. Referring to the prior preferred system shown in fig. 1 and 2, wherein like numerals indicate like parts, a powdered brominated anionic styrenic polymer, preferably brominated anionic polystyrene powder, having properties such as those of powdered Saytex HP-3010 polymer (Albemarle Corporation), is fed from hopper 10 into powder feeder 12 and through hopper 14 into kneader 15. The polymer emerging from the kneader 15 is introduced into a crosshead extruder 16. The kneader-extruder heats and forms a melt of brominated anionic styrenic polymer and the melt exits the die 18 as a strand of generally continuous polymer extruded from the die onto a moving conveyor belt 20. In the system schematic, the belt 20 is inclined upwardly so that the upper distal end of the belt is generally about 18 to about 36 inches (about 45.7 to about 91.4cm) above the vibratory classifier 30. The spray system, generally designated 33, forms and distributes a mist or spray of water onto the hot polymer strands located on the upper portion of the belt 20, which belt 20 moves in the direction indicated by arrow 35. The cooled noodles are then carried by the belt 20 under air knives 37, 37 which cut or break at least part of the noodles into granules. On the underside of the belt 20, near the air cutters 37, 37 are vacuum inlets 39, 39 of a conventional vacuum manifold (not shown) that draws residual water and fines away from the underside of the belt 20. The resulting particles are discharged at the upper outer end of the belt 20 and fall under gravity to the operatively upper surface of a classifier 30, which may be a vibratory classifier as shown in fig. 3. The impact of the fall may cause fragmentation of the chunks falling from the belt 20, which may form additional particles. Thus, the particles in the system shown in fig. 1, 2 are mainly formed in the area from the air cutters 37, 37 to the area including the classifier 30. The fines are separated and collected in a classifier 30 which continuously feeds the particles left behind after separation onto a transmission device 40, such as a segmented conveyor belt or a bucket elevator, arranged to receive and forward or upward transport the particles to a height suitable for feeding the particles into a suitable heavy duty packaging container 50, such as a Supersack or Gaylord container. A small amount of particle breakage may occur during this packaging step, which is generally not important, but this can be minimized by reducing the drop height from the transmission to the packaging container.

It will be readily appreciated that the system shown in figures 1 and 2 can be suitably modified to achieve the formation of substantially fines-free pelletized brominated anionic styrenic polymer. For example, kneaders such as Buss Ko-kneaders and associated crosshead extruders may be replaced by suitable twin-screw extruders, such as for example all twin-screw or single-screw extruders having a length/diameter (L/D) ratio equal to or greater than 20/1. Die face pelletizers or eccentric pelletizers can also be used in place of the strand die, conveyor, and vibratory sizers.

Granules of the invention

According to the present invention, a pelletized brominated anionic styrenic polymer has little, if any, fines particles or dust formed and packaged. It is generally stated that the particles of the present invention are comprised of undoped brominated anionic styrenic polymer having a bromine content of at least about 50 wt% (preferably at least about 60 wt%) and wherein at least about 70 wt% (preferably at least about 75 wt%) of the particles are retained on a U.S. standard sieve No. 40 and no more than about 30 wt% (preferably no more than about 25 wt%) of the particles are retained on a U.S. standard sieve No. 5. In a more preferred embodiment, the particles have a bromine content of at least about 64 wt%, and particularly preferred brominated anionic styrenic polymers have a bromine content in the range of about 67 wt% to about 69 wt%. The brominated anionic styrenic polymers of the invention, such as brominated anionic polystyrene, are very rarely more than about 71 wt% bromine, and therefore particularly preferred brominated anionic styrenic polymers of the invention, which are pelletized, have a bromine content in the range of about 67 wt% to about 71 wt%. Also preferred are pelletized brominated anionic styrenic polymers of the present invention wherein the melt flow index (astm d1238-99) is at least about 4 and preferably at least about 5.

Particularly preferred particles of the invention are formed from brominated anionic styrenic polymer having a bromine content in the range of from about 67 wt% to about 71 wt%, more preferably in the range of from 67 wt% to about 69 wt% bromine, and wherein at least about 80 wt% (more preferably at least about 85 wt%, and most preferably at least about 90 wt%) of the particles are retained on a standard U.S. sieve No. 40, and no more than about 20 wt% (more preferably no more than about 15 wt%, and most preferably no more than about 10 wt%) of the particles are retained on a standard U.S. sieve No. 5. Of all the previously pelletized products, the preferred brominated anionic styrenic polymer in all cases is brominated anionic polystyrene.

Another feature of the preferred granules of the present invention is that when poured into a 20mL cylindrical clear plastic capped bottle, there is essentially no visible dust or powder on the inside wall of the bottle.

Use of particles as flame retardants

The particles of the present invention can be used as flame retardants for many thermoplastic polymers. The polymer may be a thermoplastic polyester, such as: polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polycyclohexylene terephthalate, etc.; thermoplastic polyamides such as nylon 6, nylon 66, nylon 6, 12, and the like; a polycarbonate; polyphenylene ethers such as poly (2, 6-dimethylphenylene ether); polysulfones; polystyrene or other styrenic homopolymers; copolymers of two or more styrene monomers, such as: styrene, methylstyrene, ethylstyrene, t-butylstyrene, α -methylstyrene, vinylnaphthalene, etc.; rubber-modified vinyl aromatic hydrocarbon-based homopolymers or copolymers (e.g., high impact polystyrene); acrylic or methacrylic polymers such as ethylene-methacrylate, ethylene-ethyl acrylate, ethylene-butyl acrylate, poly (methyl methacrylate), and the like; ethylene-vinyl acetate copolymers; acrylonitrile copolymers and terpolymers such as acrylonitrile-butadiene-styrene copolymer (ABS) and styrene-acrylonitrile copolymer (SAN) and the like; polyolefins such as polyethylene, polypropylene, poly (1-butene) and copolymers of ethylene with one or more higher alkenyl olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene; and mixtures, blends or composites of different polymers, such as mixtures of poly (2, 6-dimethylphenylene ether) with polystyrene, mixtures of polycarbonate and polystyrene, and similar mixtures thereof. Other polymers are polymers that are flame retarded by the use of the flame retardant additives of the particles of the invention herein, including rubbery block copolymers such as styrene-ethylene-styrene, styrene-ethylene-propylene-styrene, styrene-ethylene-butylene-styrene, and the like; a polyurethane; an epoxy resin; a phenolic resin; elastomers such as natural rubber, butyl rubber, GRS, GRN, EPDM, and the like; polysiloxanes, and the like. Further, the polymer may be crosslinked by chemical means or radiation means as appropriate. A wide variety of non-flame retardant polymers suitable for use in the practice of the present invention are available from a variety of commercial sources.

A preferred group of base polymers that can be effectively flame retarded by the use of the particles of the present invention are polyesters. Thermoplastic polyesters, commonly referred to as polyalkylene terephthalates, are reaction products between aromatic dicarboxylic acids or their reactive derivatives, such as methyl esters or anhydrides, and aliphatic, cycloaliphatic, or araliphatic diols, and mixtures of such reaction products. Examples of such thermoplastic polyesters include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, 1, 4-cyclohexanedimethylene terephthalate, and corresponding copolyesters and mixtures, including mixtures of one or more thermoplastic polyesters with one or more other thermoplastic polymers such as polycarbonates, especially aromatic polycarbonates.

Preferred thermoplastic polyesters contain at least 80% by weight, and preferably at least 90% by weight, based on the dicarboxylic acid component, of terephthalic acid and at least 80% by weight, and preferably at least 90% by weight, based on the diol component, of ethylene glycol and/or 1, 4-butanediol units.

In addition to terephthalic acid units, the thermoplastic polyesters may preferably contain up to 20 mole% and preferably up to 10 mole% of other aromatic or cycloaliphatic C_8-14Dicarboxylic acids or aliphatic C_4-12Units of dicarboxylic acids, for example phthalic acid, isophthalic acid, 2, 6-naphthylene dicarboxylic acid, 4' -diphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid or cyclohexanediacetic acid.

In addition to ethylene glycol and 1, 4-butanediol units, the preferred thermoplastic polyesters may contain up to 20 mole% and preferably up to 10 mole% of other aliphatic C_3-12Diols or cycloaliphatic C_6-12Diols, for example 1, 3-propanediol, 2-ethylpropane-1, 3-diol, neopentyl glycol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethylene glycol, 3-ethylpentane-2, 4-diol, 2-methylpentane-2, 4-diol, 2, 3-trimethylpentane-1, 3-diol, 2-ethylhexane-1, 3-diol, 2-diethylpropane-1, 3-diol, 2, 5-hexanediol, 2-bis (4-hydroxy-cyclohexyl) propane, 2, 4-dihydroxy-1, 1, 3, 3-tetramethylcyclobutane, 2-bis (4- (2-hydroxy-ethoxy) phenyl) propane or 2, units of 2-bis- (4- (2-hydroxypropoxy) phenyl) propane.

The polyalkylene terephthalates may be branched with relatively small amounts of trihydro or tetrahydroalcohols or tribasic or tetrabasic carboxylic acids. See, for example, U.S. Pat. No. 3,692,744 in this regard. Examples of preferred branching agents are trimesic acid, trimellitic acid, trimethylolethane and trimethylolpropane and pentaerythritol.

Particularly preferred thermoplastic polyesters are those which have been prepared exclusively from terephthalic acid or its reactive derivatives, such as dialkyl esters, with ethylene glycol and/or 1, 4-butanediol, and also mixtures of these polyalkylene terephthalates. Preferred mixtures of polyalkylene terephthalates contain 1 to 50 wt.% of polyethylene terephthalate and 99 to 50 wt.% of polybutylene terephthalate. Particularly preferred mixtures contain 1 to 30% by weight of polyethylene terephthalate and 99 to 70% by weight of polybutylene terephthalate.

The polyalkylene terephthalates preferably used generally have an intrinsic viscosity of 0.4 to 1.5dl/g, preferably 0.5 to 1.3dl/g, more preferably 0.55 to 1.2dl/g, measured in phenol-o-dichlorobenzene (1: 1 weight ratio) at 25 ℃. An Ubbelohde viscometer was used.

Most preferably the intrinsic viscosity of the polyethylene terephthalate and polybutylene terephthalate and mixtures thereof is within this range. It is well known that manufacturers of engineering resins of polyethylene terephthalate synthesize recycled PET whose products are recovered from pure PET (generally 0.55 to 0.70IV) or from industrial waste, polyester film waste, bottles and small amounts of polyester fiber waste.

In addition to thermoplastic polyesters, which may be used in the practice of the present invention include, for example: polyether esters, polyether-polycarbonate mixtures or blends, polyester-ABS mixtures or blends, polyester-MBS mixtures or blends, and impact-modified thermoplastic polyesters.

The polyalkylene terephthalates may be produced by known methods. See, e.g., Encyclopedia of Polymer Science and Technology, Vol.11, pages 62-128, John Wiley & Sons, Inc., copyright 1969; and Kirk-Othmer, Encyclopedia of chemical Technology, 4th Ed., Vol.19, pages 609-653, John Wiley & Sons, Inc., copyright 1996.

Another group of preferred thermoplastic polymers that may be effectively flame retarded using the particles of the present invention are polyamides, sometimes referred to as nylon polymers. The base polymer of the polyamide may be any amorphous and/or partially crystalline, predominantly aliphatic/cycloaliphatic or partially aromatic thermoplastic polyamide. Generally, the materials are prepared by polycondensation and/or polymerization of diamines which are predominantly or wholly aliphatic or cycloaliphatic, or diamines which are partially or wholly aromatic, with carboxylic acids or lactams which are predominantly or wholly aliphatic or cycloaliphatic, or carboxylic acids or lactams which are predominantly or predominantly aromatic. Amines typically used to form polyamides include such diamines as: hexamethylenediamine, tetramethylenediamine, 2, 4-and 2, 4, 4-trimethylhexamethylenediamine, diaminodicyclohexylmethane (isomers), diaminodicyclohexylpropane (isomers), isophoronediamine (isomers) and xylylenediamine. Also useful as starting materials are aminocarboxylic acids such as e-aminocaproic acid, or ω -aminocarboxylic acids such as ω -aminolaurate and ω -aminodecanoic acid. The carboxylic acids generally used are aliphatic, or mixed aliphatic-aromatic dicarboxylic acids (having less than 50% by weight of aromatic components), such as adipic acid, 2, 4-and 2, 4, 4-trimethyladipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, isophthalic acid, terephthalic acid.

Copolyamides obtained from the main known monomers can also be used.

Illustrative polyamides which may be used in the practice of the present invention are the following polyamides, such as: nylon 6, nylon 6,9, nylon 6, 10, nylon 6, 12, nylon 11, nylon 12, nylon 6/6, 6 copolymers, and high temperature nylons such as nylon 4, 6, and partially aromatic nylons (such as Ixef polyarylamide PA MXD6, from Solvay, Zytel HTN from DuPont, and Amodel polyarylamide from Solvay). Other polyamides that may be used include Arlen modified polyamide 6T from Mitsui Chemicals, Inc., Genestar PA9T Polyamide resin from Kuraray company, Stanyl Polyamide 46 from DSM, Vydyne Polyamide 6/66 copolymer from Monsanto, Polyamide 612(Vestamid D from Creanova), and similar polyamides. For the different nylon polymers, nylon 6 and nylon 6,6 are the preferred base polymers.

The invention can also be applied to thermoplastic mixtures or blends of one or more polyamides, such as for example: polyamide-polyolefin mixtures or blends, polyamide-ionomer mixtures or blends, polyamide-ABS mixtures or blends, polyamide-EPDM mixtures or blends, polyamide-polyphenylene ether mixtures or blends, or impact modified polyamides.

Methods for preparing polyamides are known and described in the literature, see for example: encyclopedia of Polymer Science and Technology, Vol.10, pages 460-482, John Wiley & Sons, Inc., copyright 1969; and Kirk-Othmer, Encyclopedia of chemical Technology, 4th Ed., Vol.19, pages 559-584, John Wiley & Sons, Inc., copyright 1996.

The following examples illustrate the practice and advantages of the present invention. These examples are not intended to limit the scope of the invention as outlined.

Example 1

The very good results obtained with the invention used are demonstrated by the operation in a system as shown in fig. 1, 2. In this system, the following devices are used:

a) the extruder system was a 140mm Buss Ko-kneader 15 having an L/D of 11/1 (but it could be 7.1 or greater) fitted with a crosshead extruder 16, the curve of the kneader screw having kneading characteristics.

b) The die 18 is a 20-hole die, the diameter of the holes being 4 mm.

c) The conveyor belt 20 was a Scheer-Bay conveyor, 14 feet long (about 4.3meters), 15 inches wide (about 38.1cm), and 3 inches in diameter (about 7.6-cm) diameter roller. The mesh belt is inclined upwardly at an angle of about 12.

d) Classifier 30 is a Witte model 200 classifier.

The vertical distance between the end of the belt 20 falling to the top of the classifier 30 is about 24 inches (about 61cm) and the vertical distance between the end of the drive train 40 and the bottom surface of the empty shipping container 50 is about 60 inches (about.152 cm).

The operating conditions of the system were as follows:

the extruder system was operated at a barrel and melt temperature of 220-240 ℃. During operation, a vacuum of 6-8 inches of mercury (about 0.21-0.28 kg/cm) was applied to both the kneader and the crosshead extruder²). The conveyor speed is 150 to 175ft/min (about 45.7 to about 53.3 m/min). The amount of water mist supplied was about 1gallon/min (about 3.791/min). The air knife was operated at 10-25psig and was positioned about 5 inches (about 12.7cm) above the belt on the conveying surface. The vacuum applied below the conveyor belt was about 2200 cubic feet/min (about 62.3 m)³Min) and two vacuum applicators, each having a nozzle area of 45 square inches (about 114.3 cm), are positioned across the belt so that the vacuum is applied directly to the surface adjacent the conveyor belt²)。

Samples of the prepared brominated anionic polystyrene particles were periodically taken from the system during the 4 hours of operation for sieving or in some cases for melt flow determination. In the screening operation, a 100 gram sample was placed on three members of the stack, the uppermost being a U.S. standard No. 5 screen, the next layer being a U.S. standard No. 40 screen, and the lowermost member being a tray for collecting fines, and the entire stack of members was tapped 10 times by hand with as consistent force as possible when the sample was placed on the uppermost screen. The contents of the 3 members were then weighed, thereby obtaining values for the weight% of particles remaining on sieve No. 5, sieve No. 40 and the fines collection tray.

In melt flow assays, a sample of the particles is used in a standardization process.

Table 1 summarizes the data obtained in this operation.

TABLE 1

Sample number	Volatile matter%	Melt flow index	Retained on sieve No. 5%	Retained on size 40 sieve%	The percentage of fine powder passing through a No. 40 sieve%
						1	0.04	5.6	8.5	91.2	0.4
2	0.04	--	8.3	91.5	0.2
						3	0.04	7.4	19.4	80.2	0.4
4	0.03	--	20.3	79.1	0.6
						5	0.04	--	12.0	87.6	0.3
6	0.04	7.5	4.4	94.3	1.3
						7	0.04	--	12.1	87.5	0.3

Example 2

The same equipment, operating conditions and sample evaluations as in example 1 were used except that the Buss Ko-kneader and crosshead extruder were replaced with a 90mm twin screw compounding extruder, a co-rotating intermeshing twin screw extruder model ZSK-90, manufactured by Werner Pfleiderer. The extruder was operated at a speed of 1200lbs/hr (about 543kg/hour) and a temperature in the range of 220-240 deg.C. In this operation, samples were taken periodically during 4 hours of operation.

Table 2 summarizes the data obtained in this operation

TABLE 2

Sample number	Volatile matter%	Melt flow index	Retained on sieve No. 5%	Retained on size 40 sieve%	The percentage of fine powder passing through a No. 40 sieve%
						1	0.27	5.6	4.1	95.9	0.0
2	0.19	--	3.1	96.3	0.6
						3	0.04	6.9	2.7	96.9	0.4
4	0.08	--	3.5	96.0	0.4
						5	0.07	--	6.7	92.4	0.9

6	0.04	7.0	2.7	97.1	0.2
						7	--	--	4.4	95.2	0.3
8	0.04	8.6	8.3	91.3	0.3
						9	--	--	4.8	94.1	1.1
10	0.04	--	4.2	95.2	0.7
						11	0.06	6.3	1.6	98.0	0.4
12	0.04	--	3.2	96.4	0.4
						13	0.04	6.9	1.7	98.0	0.3
14	0.04	--	4.9	95.1	0.0
						15	0.06	--	3.4	95.4	0.0
16	0.06	7.4	2.2	97.1	0.7
						17	0.04	--	3.2	96.4	1.0
18	0.08	7.0	0.7	97.4	1.9
						19	0.04	--	0.5	98.9	0.6
20	0.04	--	4.1	95.5	0.4
						21	0.04	5.4	4.5	95.3	0.2
22	0.08	--	4.2	95.4	0.4
						23	0.07	5.3	1.6	95.8	2.6
24	0.07	--	1.3	97.9	0.8
						25	0.08	--	2.6	95.9	1.5
26	0.06	7.7	6.1	93.6	0.5
						27	0.04	--	4.3	95.4	0.3
28	0.04	5.6	2.8	97.0	0.3
						29	0.04	--	2.9	96.4	0.7
30	0.04	--	1.8	96.2	2.1
						31	0.04	4.9	2.3	96.0	1.7
32	0.04	--	1.7	96.8	1.5
						33	0.04	5.4	2.0	97.4	0.6
34	0.04	--	2.0	96.7	1.4
						35	0.08	--	1.8	96.9	1.3
36	0.08	5.8	2.7	95.8	1.5
						37	0.04	5.8	2.6	97.0	0.4
38	0.04	--	4.4	95.0	0.6

39	0.04	5.2	4.1	95.7	0.3
						40	0.04	--	4.5	95.2	0.3
41	0.02	--	2.2	97.4	0.4
						42	0.04	5.5	5.2	94.7	0.1
43	0.04	--	7.1	92.4	0.2
						44	0.04	5.4	6.5	93.0	0.4
45	0.04	--	5.3	94.6	0.2
						46	0.04	--	1.7	97.9	0.4
47	0.04	5.2	6.5	92.8	0.8
						48	0.04	--	4.6	94.8	0.6
49	0.04	9.0	2.6	96.4	1.0
						50	0.06	--	2.2	96.8	1.0
51	0.04	--	5.3	94.5	0.2
						52	0.04	5.7	7.7	92.2	0.1
53	0.04	--	6.6	93.2	0.2
						54	0.04	7.7	4.6	95.4	0.0
55	0.07	--	2.5	97.0	0.5
						56	0.06	--	2.4	96.9	0.7
57	0.04	9.2	4.0	93. 9	2.2
						58	0.04	--	7.6	92.1	0.3
59	0.04	4.6	5.9	93.3	0.8
						60	0.04	--	6.3	93.5	0.2
61	0.06	--	5.5	93.5	1.0
						62	0.04	7.8	6.6	93.2	0.3
63	0.07	--	6.7	93.1	0.2
						64	0.04	5.7	3.6	95.8	0.6
65	0.04	--	3.8	95.4	0.8
						66	0.04	--	2.9	96.2	0.9
67	0.04	5.4	3.3	96.1	0.5
						68	0.04	--	1.7	98.1	0.2
69	0.04	6.1	2.6	97.0	0.5
						70	0.04	--	5.5	94.1	0.5
71	0.04	--	4.2	95.6	0.2

72	0.03	--	10.3	88.7	1.0
						73	0.04	--	7.0	92.7	0.3
74	0.00	5.2	6.0	93.9	0.1
						75	0.04	--	5.9	93.2	0.8
76	0.04	--	3.5	95.9	0.6
						77	0.04	5.8	5.2	93.3	1.5
78	0.06	--	5.1	94.7	0.2
						79	0.11	6.8	5.1	94.6	0.2
80	0.06	--	5.2	94.4	0.4
						81	0.06	--	4.2	94.9	0.9
82	0.04	5.8	3.3	96.0	0.7
						83	0.04	--	11.5	88.3	0.3
84	0.04	6.2	7.2	90.8	0.1
						85	0.04	--	8.9	90.7	0.4
86	0.00	--	8.5	91.0	0.5
						87	0.00	7.2	15.0	84.8	0.2
88	0.06	--	11.0	88.7	0.2
						89	0.04	6.9	9.1	90.8	0.1
90	0.04	--	6.7	93.2	0.1
						91	0.04	--	8.4	91.3	0.3
92	0.04	6.2	7.3	92.6	0.1
						93	0.04	--	--	--	--
94	0.04	6.0	9.0	90.8	0.2
						95	0.06	--	3.3	96.3	0.4
96	0.04	--	8.4	91.4	0.2
						97	0.04	6.1	3.6	96.0	0.4
98	0.04	--	2.9	97.0	0.1
						99	0.04	5.8	4.2	95.4	0.4
100	0.04	--	7.9	91.8	0.3
						101	0.04	--	8.0	91.8	0.2
102	0.04	7.3	5.3	94.4	0.3
						103	0.04	--	9.0	90.6	0.4
104	0.04	6.2	3.7	96.0	0.4

105	0.03	--	4.1	95.0	0.9
						106	0.04	--	8.6	91.1	0.3
107	0.04	6.0	8.2	91.4	0.4
						108	0.00	--	6.1	93.7	0.2
109	0.04	--	6.9	92.9	0.2
						110	0.04	--	5.4	94.6	0.0
111	0.04	--	5.4	94.2	0.4
						112	0.06	6.3	7.1	92.8	0.2
113	0.04	--	3.4	96.2	0.5
						114	0.04	--	8.9	90.5	0.6
115	0.04	--	7.9	91.5	0.6
						116	0.03	--	6.7	92.3	1.0
117	0.04	6.3	9.8	90.0	0.2
						118	0.04	--	11.4	88.2	0.4
119	0.04	6.1	8.7	90.9	0.4
						120	0.04	--	8.1	91.5	0.4
121	0.03	--	10.3	89.5	0.2
						122	0.04	6.2	7.4	92.2	0.4
123	0.04	--	7.8	91.8	0.5
						124	0.04	5.9	7.5	92.2	0.3
125	0.04	--	9.1	90.8	0.1
						126	0.10	--	3.2	96.6	0.2
127	0.04	5.9	4.0	95.4	0.6
						128	0.04	--	12.8	85.5	1.8
129	0.00	5.6	5.8	93.5	0.6
						130	0.00	--	7.9	91.7	0.4
131	0.00	--	8.9	90.4	0.7
						132	0.04	5.2	7.2	92.6	0.2
133	0.04	--	7.0	92.5	0.5
						134	0.04	6.6	7.0	92.6	0.4
135	0.04	--	8.9	90.7	0.4
						136	0.04	--	5.0	94.2	0.8
137	0.04	7.7	4.5	93.7	1.9

The statistical results are shown in tables 1 and 2 over 3 total statistical ranges, with relative percentages retained on sieves No. 5 and 40 indicating that the percentage retained on sieve No. 5 is between 0 and 16 wt% and 83-100 wt% is retained on sieve No. 40. On the same statistical basis, 0-2% by weight of the fines passed through a No. 40 sieve. Thus, the process statistically considers yields that can provide the desired product to range from 98% to 100%.

Unless specifically stated otherwise, if the word "a" or "an" is used herein, it is not intended to be limiting, and should not be construed as limiting the specification or the claims to a single element to which the word refers. In addition, if the use of "a" or "an" is intended herein, one or more such elements are encompassed, unless the context clearly dictates otherwise.

All documents referred to herein are incorporated by reference in their entirety as if fully set forth in this document.

The present invention is susceptible to considerable variation within the spirit and scope of the appended claims. The above description is therefore not intended to be limiting, and should not be construed as limiting the invention to the particular exemplifications presented hereinabove. Further, what is intended to be covered is as set forth in the ensuing claims and the equivalents thereof permitted as a matter of law.

Claims (32)

1. Particles of undoped brominated anionic styrenic polymer having a bromine content of at least about 50 wt% and wherein at least about 70 wt% of the particles are retained on a U.S. standard No. 40 sieve and no more than about 30 wt% of the particles are retained on a U.S. standard No. 5 sieve.

2. The particle of claim 1 wherein the bromine content is at least about 60 wt%.

3. The particle of claim 1 wherein the bromine content is at least about 64 wt%.

4. The particle of claim 1, wherein the bromine content ranges from about 67 wt% to about 71 wt%.

5. The particle of claim 1, wherein the bromine content ranges from about 67 wt% to about 69 wt%.

6. The particle of any of claims 1-5, wherein the particle has a melt flow index of at least 4.5.

7. The granule of claim 6 wherein the melt flow index is at least 5.5.

8. The granule of any of claims 1-5 wherein at least about 75 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 25 wt% of the granule is retained on a U.S. Standard sieve No. 5.

9. The granule of any of claims 1-5 wherein at least about 80 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 20 wt% of the granule is retained on a U.S. Standard sieve No. 5.

10. The granule of any of claims 1-5 wherein at least about 85 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 15 wt% of the granule is retained on a U.S. Standard sieve No. 5.

11. The granule of any of claims 1-5 wherein at least about 90 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 10 wt% of the granule is retained on a U.S. Standard sieve No. 5.

12. The granule of any of claims 1-5 wherein at least about 75 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 25 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 4.5.

13. The granule of any of claims 1-5 wherein at least about 80 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 20 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 4.5.

14. The granule of any of claims 1-5 wherein at least about 85 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 15 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 4.5.

15. The granule of any of claims 1-5 wherein at least about 90 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 10 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 4.5.

16. The granule of any of claims 1-5 wherein at least about 75 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 25 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 5.5.

17. The granule of any of claims 1-5 wherein at least about 80 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 20 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 5.5.

18. The granule of any of claims 1-5 wherein at least about 85 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 15 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 5.5.

19. The granule of any of claims 1-5 wherein at least about 90 wt% of the granule is retained on a U.S. Standard sieve No. 40 and no more than about 10 wt% of the granule is retained on a U.S. Standard sieve No. 5, and wherein the granule has a melt flow index of at least 5.5.

20. Particles of undoped brominated anionic polystyrene having a bromine content of at least about 50 weight percent and wherein at least about 70 weight percent of the particles are retained on a standard U.S. sieve No. 40 and no more than about 30 weight percent of the particles are retained on a standard U.S. sieve No. 5.

21. The particles of claim 20 wherein at least about 80 wt% of the particles are retained on a U.S. standard sieve No. 40 and no more than about 20 wt% of the particles are retained on a U.S. standard sieve No. 5, wherein the bromine content is at least about 60 wt%, and wherein the polystyrene has a melt flow index of at least 4.5.

22. The particles of claim 20 wherein at least about 90 wt% of the particles are retained on a U.S. standard sieve No. 40 and no more than about 10 wt% of the particles are retained on a U.S. standard sieve No. 5, wherein the bromine content ranges from about 67 to about 71 wt%, and wherein the polystyrene has a melt flow index of at least 5.5.

23. A process for preparing an undoped particulate brominated anionic styrenic polymer, which process comprises:

A) forming a ribbon of molten undoped brominated anionic styrenic polymer;

B) cooling the noodles and breaking the noodles into particles thereon by flowing downwardly directed pressurized air onto a foraminous conveyor belt; and is

C) The pellets fall down into a classifier that removes fines from the pellets.

24. The process of claim 23 wherein the undoped brominated anionic styrenic polymer used in a) is undoped brominated anionic polystyrene.

25. The process of claim 23, wherein the process produces no more than about 2 wt% fines passing through a U.S. standard No. 40 sieve.

26. The method of any one of claims 23-25, wherein the polymer used has a melt flow index of at least about 4.5.

27. The method of any one of claims 23-25, wherein the polymer used has a melt flow index of at least about 5.5.

28. A process as claimed in any one of claims 23 to 25 wherein the polymer used has a bromine content of at least 50 wt%.

29. A process as claimed in any one of claims 23 to 25 wherein the polymer used has a bromine content of at least 60 wt%.

30. The method of any one of claims 23-25, wherein the polymer used has a bromine content ranging from about 67 wt% to about 71 wt%.

31. A process as claimed in any one of claims 23 to 25 wherein the polymer used has a bromine content of at least 60 wt% and a melt flow index of about 4.5.

32. A method as in any of claims 23-25 wherein the polymer used has a bromine content in the range of about 67 wt% to about 71 wt% and a melt flow index of about 5.5.