EP0297112A1

EP0297112A1 - Flame retarded modified polyphenylene esters having improved flow characteristics

Info

Publication number: EP0297112A1
Application number: EP87906011A
Authority: EP
Inventors: Thomas Patrick Fidelle; Charles Turner Ludwig; Robert John Nulph
Original assignee: Great Lakes Chemical Corp
Current assignee: Great Lakes Chemical Corp
Priority date: 1986-11-14
Filing date: 1987-09-08
Publication date: 1989-01-04
Also published as: JPH01501315A; EP0297112A4; WO1988003542A1

Abstract

Des compositions d'éthers de polyphénylène à inflammation retardée modifiées à l'aide d'une résine alkénylaromatique qui présentent des caractéristiques d'écoulement améliorées comprennent une résine alkénylaromatique bromée, un diester de l'acide tétrabromophtalique et un agent d'amélioration du retard à l'inflammation.Compositions of delayed-ignition polyphenylene ethers modified with an alkenylaromatic resin which have improved flow characteristics include a brominated alkenylaromatic resin, a tetrabromophthalic acid diester and a delay-enhancing agent inflammation.

Description

FLAME RETARDED MODIFIED POLYPHENYLENE ESTERS HAVING IMPROVED FLOW CHARACTERISTICS

Background of the Invention Field of the Invention.

This invention relates to modified polyphenylene ether resins having improved flow properties and, in particular, it relates to modified polyphenylene ether resins incorporating a brominated alkenyl aromatic resin, a diester of tetrabromophthalic acid and a flame retardant enhancer such as antimony trioxide.

Description of the Prior Art. Modified polyphenylene ether ("MPPE") resins are a well known class of thermoplastic resins which combine relatively high impact, excellent thermal stability, low water absorption and a low degree of flammability. These resins are produced by alloying polyphenylene ether polymers with alkenyl aromatic resins such as impact polystyrene. The terms "modified polyphenylene ether" and "MPPE" are used herein to refer broadly to all of these alloyed resins.

Even though modification with polystyrene does increase ease of molding of unmodified polyphenylene ethers, such MPPE resins often exhibit far from ideal flow properties. Thus further flow modification is usually required to provide resins that are readily moldable at moderate temperatures.

Although unmodified polyphenylene ethers exhibit substantial inherent flame resistance, modification with impact polystyrene significantly increases their flammability. Since MPPE resins find increasing application in electrical and electronic equipment and appliances, a high level of flame retardancy is usually required.

Aromatic phosphate esters have been used for some time to increase the flame retardancy of MPPE resins. As noted in U.S. Patent No. 4,579,901, Table 1, when sufficient amounts of the esters are added to provide a good degree of flame retardancy, the compositions are also plasticized\ resulting in improved melt flow behavior. However, such compositions also exhibit a serious loss of heat resistance, a marked disadvantage. Another problem is that some of the volatile fluid phosphate esters often migrate to the surface during molding, accumulating as droplets near the molding vents. This effect, known in the trade as "juicing," is not only objectionable from an appearance standpoint, but it may also result in stress cracking. The plastic part as molded may be under stress and the accumulated liquid phosphate ester can induce cracking. For example, see U.S. 4,503,178, column 1, line 65, to column 2, line 11.

Therefore, it is a principal object of this invention to provide alkenyl aromatic resin modified polyphenyl ether compositions having flame retardancy and improved flow properties during molding.

Another object of this invention is to provide such flame retardant compositions which have reduced amounts of the flow enhancer that accumulates on the surface of molded parts. SUMMARY OF THE INVENTION The foregoing and other objects, advantages, and features of the subject invention may be obtained with a flame retarded modified polyphenylene ether resin composition based on a polyphenylene ether homo- or co-polymer modified with an alkenyl aromatic resin. The modified polyphenylene ether resin incorporates effective amounts of a brominated alkenyl aromatic resin, a diester of tetrabromophthalic acid, and an enhancing agent. Preferably, the modified polyphenylene ether resin incorporates about 1-20 percent by weight of a brominated alkenyl aromatic resin of the formula:

where R and R' are H or CH₃; x may be 2 to 5; y is 1 when R is CH₃ and 0 to 3 when R is H; n is 5 to 10000; about 1-20 percent by weight of a diester of tetrabromophthalic acid of the formula:

where R" and R"' independently represent straight or branched C_4-18 aliphatic groups; C_4-18 alkenyl groups; C_2-6 haloalkyl groups; benzyl, phenyl, and halo-substituted benzyl and phenyl; and R₂(OCH₂CH(R₃))_xOH, where R₂ may be CH₃, C₂H₅, or H; R₃ may be CH₃ or H; and X is 1 to 10; and about 1-15 percent by weight of an enhancing agent such as antimony trioxide, all by weight of the overall flame retarded resin composition.

The present invention also encompasses premixed concentrates of the polymer additives of this invention. Such additive concentrates may comprise about 1-20 parts by weight each of brominated alkenyl aromatic resin and diester of tetrabromophthalic acid, and, optionally, about 1-15 parts by weight of an enhancing agent. Advantageously, such concentrates may be provided in blended form with modified polyphenylene ether resin as a diluent.

By utilizing the unique flame retardant agent combination of this invention, a high degree of flame retardance can be imparted to modified polyphenylene ether resin compositions without adversely affecting the flow properties of the resin and without encountering the problem of "juicing" experienced with prior art flame retardant and flow enhancers.

DESCRIPTION OF THE PREFERRED EMBODIMENTS It has now been discovered that modified polyphenylene ethers having a high degree of flame retardancy, improved flow, and much reduced tendency for juicing can be realized by using as the flame retardants therein the combination of a brominated alkenyl aromatic resin, a diester of tetrabromophthalic acid and an enhancing agent.

The polyphenylene ethers to which this invention is directed are also referred to as polyoxyphenylenes and as poly- (phenylene oxide)s. Such products, some of them well-known commercially as discussed below, are characterized by their excellent thermal stabilities and mechanical properties. Those contemplated in this invention have backbones which consist only of aromatic structures having ether linkages. Variations in the location of the ether structures, ortho, meta, or para, on the aromatic units produces an array of possible homo- and co-polymers, all envisioned as potential substrates for this invention. In particular, application is directed to the para-substituted polyphenylene ethers.

It has been discovered in the development of the polyphenylene ethers that they can be alloyed with other resins, particularly polystyrenics, to produce modified polyphenylene ethers more readily useful in molding operations while maintaining many of the desirable thermal, mechanical, and chemical properties of the base resins.

For example, General Electric's "NORYL" resins are polystyrene alloys with the homopolymer of 2,6-dimethylphenol, and Borg Warner's "PREVEX" resins are polystyrene alloys with the copolymer of 2,6-dimethγlphenol and 2,3,6-trimethylphenol. There appears to be a semantic tendency to refer to the NORYL alloys as "polyphenylene oxides" and the PREVEX alloys as "polyphenylene ethers." The terminology "polyphenylene ethers" and "MPPE" is used herein to refer not only to both of these commercial examples but also to other modified polyphenylene ethers and oxides. Further details of various MPPE resins and their technology may be found in Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Vol. 9, pp 130-131 and Vol. 18, pp

594-605, and in Modern Plastics Encyclopedia, 1985-86 Edition, pp 34 and 36.

Brominated alkenyl aromatic resins are utilized in accordance with this invention as flame retardant additives in combination with tetrabromophthalic acid diesters and enhancing agents in the present compositions. Preferably the brominated alkenyl aromatic resins have the structural formula:

where R and R' are H or CH₃; x may be 2 to 5; y is 1 when R is CH₃ and 0 to 3 when R is H; n is 5 to 10000.

These brominated alkenyl aromatic resins may be prepared by bromination of the alkenyl aromatic resin in a halogenated hydrocarbon solvent using a metal halide catalyst. Alternatively, brominated monomer such as di- or tri-bromostyrene may be polymerized as known in the art to give the brominated alkenyl aromatic resins.

Suitable brominated alkenyl aromatic resins include polybrominated polystyrene having a degree of bromination lying in the range of about 2-3 and a degree of polymerization lying in the range of of about 5-10,000. An especially preferred material is a lower molecular weight polybrominated polystyrene (degree of polymerization about 27, degree of bromination about 2.6). Other suitable materials include brominated poly-(alpha-methylstyrene) and brominated poly-(4-methylstyrene). The second essential component of the flame retardant system is a diester of tetrabromophthalic acid. Preferably, the diester has the formula:

where R" and R"' independently represent straight or branched C_4-18 aliphatic groups; C_4-18 alkenyl groups; C_2-6 haloalkyl groups; benzyl, phenyl, and halo-substituted benzyl and phenyl; and R₂(OCH₂CH(R₃))_xOH, where R₂ may be CH₃, C₂H₅, or H; R₃ may be CH₃ or H; and X is 1 to 10. A preferred material is di-(2-ethylhexyl) tetrabromophthalate, a product commercially available from Great Lakes Chemical Corporation under the trademark "DP-45." Other suitable materials include 2-hydroxypropyl methoxy polyoxyethylene glycol tetrabromophthalate, commercially available from Pennwalt Corp as "RC 9571, and other alkyl esters of tetrabromophthalic acid. A third essential component of the flame retardant system is an enhancing agent or so-called synergist for the bromine contained in the brominated alkenyl aromatic resin and the diester of tetrabromophthalic acid. In accordance with the present invention certain metal compounds are employed with the bromine-containing compounds of this invention to promote a cooperative effect there between and thus to enhance the flame retardancy of the resultant plastic composition as compared to the flame retardancy of either one component used separately.

Suitable enhancing agents include oxides and halides of antimony, arsenic, bismuth, tin and zinc. Exemplary enhancing agents include Sb₂O₃, Sb₂O₅, SbCl₃, SbBr₃, SbI₃, SbOCl, As₂O₃, As₂O₅, ZnBO₄, BaB₂O₄ H₂O, 2 ZnO-3 B₂O₃·3.5 H₂O and stannous oxide hydrate. The preferred enhancing agent is antimony trioxide.

The brominated alkenyl aromatic resin is utilized in accordance with the present invention in an effective amount, that is, any amount which, when used with the other flame retardant additives, will achieve the desired level of flame retardants in the modified polyphenylene ether resin. In general, the amount of brominated alkenyl aromatic resin employs will lie in the range of about 1-20 percent, preferably 2-10 percent, by weight, based on the total weight of the flame retarded MPPE resin composition. Similarly, the diester of tetrabromophthalic acid is employed in an amount effective to achieve the desired level of flame retardants in the MPPE, when used in combination with the other agents of this invention. Thus, the amount of diester generally employed lies in the range of about 1-20 percent, preferably about 2-10 percent, by weight, based on the total weight of the MPPE resin composition. Higher amounts of the brominated alkenyl aromatic resin and diester of tetrabromophthalic acid may be employed so long as the desired end result is achieved, that is, so long as the MPPE is satisfactorily flame retarded and the melt flow and other physical properties are not adversely affected.

The amount of enhancing agent employed in the present invention compositions is any amount which when used with said bromine-containing flame retardants will promote a cooperative effect therebetween. In general, the amount employed is from about 1% to about 15%, preferably from about 2% to about 10%, by weight, based on the total weight of the MPPE resin composition. Higher amounts can be used as long as the desired end result is achieved.

It is also within the scope of the present invention to employ other materials in the present invention composition where one so desires to achieve a particular end result. Such materials include, without limitation, adhesion promotors; antioxidants; antistatic agents; antimicrobials; colorants; flame retardants in addition to the bromine containing flame retardants described herein; heat stabilizers; light stabilizers; pigments; plasticizers; preservatives; ultraviolet stabilizers and fillers. For a complete listing of these other additives, See Modern Plastics Encyclopedia, ibid., pp.104-176.

The amount of such other materials employed in the present invention compositions can be any quantity which will not substantially adversely affect the desired results derived from the present invention compositions. Thus, the amount used can be zero (0) percent, based on the total weight of the composition, up to that percent at which the composition can still be classified as a plastic. In general, such amount will be from about 0% to about 75% and more desirably from about 1% to about 50%.

In general, the modified polyphenylene ether composition is formulated using methods known in the art. Thus, a previously alloyed composition of polyphenylene ether homo- or co-polymers with an alkenyl aromatic resin such as polystyrene may be compounded with the other agents in accordance with this invention using procedures generally known to those skilled in the art. For example, a concentrate of the flame retardant additives in MPPE may be formulated, with the concentrate thereafter being compounded with additional MPPE and other additives in order to achieve the desired formulation. Other suitable formulating methods may be employed.

EXAMPLES Examples 1-9 Compounding/Injection Molding Procedures: Concentrates of the flame retardant additives in MPPE were made and then let down to the desired level. As an example, 175g of MPPE were charged to a Brabender Prep-Center mixing bowl, preheated to 240°C, and di-(2-ethylhexyl) tetrabromophthalate, 175g, was added over a 5-mihute period, resulting in a 50% concentrate. A number of identical batches were compounded which were then granulated and combined. For a typical let-down, 220g of the 50% concentrate, 66g brominated polystyrene, 22g antimony trioxide, and 1892g MPPE were combined and extruded through a 1-1/4 inch diameter Brabender extruder fitted with a single stage screw and with all zones set at 270°C. The extrudate contained 5% di-(2-ethylhexyl) tetrabromophthalate, 1% antimony trioxide, and

3% brominated polystyrene. Other final concentrations were made by appropriate selection and let down of charged constituents.

All granulated let-down extrudates were injection molded in a 30-ton Newbury molder fitted with interchangeable

ASTM cavity dies. Barrel zone temperatures were set at 480°F, screw speed set at 100 rpm and sufficient injection pressure utilized to maintain a 1/4-inch injection cushion.

Compositions of Examples 1-9, prepared by the foregoing procedure, are detailed in Table I. The compounding resin utilized was Noryl 731 impact polystyrene modified polyphenylene ether homopolymer commercially available from General Electric

Corp.

LMBPS - Low molecular weight brominated polystyrene.

Pyro-Chek 68PB-Brominated polystyene commercially available from Ferro Corporation.

DTBP - Di-(2-ethylhexyl) tetrabromophthalate commercially available from Great Lakes Chemical Corporation under the trademark "DP-45."

RC 9571 - 2-Hydroxypropyl methoxy polyoxyethylene glycol tetrabromophthalate (ethoxy repeating unit = 7 average) commercially available from Pennwalt Corp.

Kronitex 50 - Triaryl phosphate commercially available from FMC Corp. The compositions of Examples 1-9 were evaluated for flammability, thermal and mechanical properties utilizing the following standard procedures:

Flammability, Thermal and Mechanical Test Procedures: Two small scale flammability tests were used to assess the flame retardancy imparted by inclusion of flame retardant additives into the alkenyl aromatic resin modified polybehylene ethers. These were the oxygen index test, ASTM D2683, and the Underwriters Laboratory (UL) Subject 94 vertical burn test, Tests for Flammability of Plastic Materials for Parts in Devices and Appliances.

The oxygen index test is a measure of ease of extinction of a burning specimen in a controlled nitrogen/oxygen atmosphere. For this test, a specimen of the dimensions 0.125 inches in thickness by 0.250 inches in width by 3.5 inches in length is clamped vertically at one end in a holder which is placed in a test column. A mixture of nitrogen and oxygen is introduced through the column. The nitrogen/oxygen ratio is adjusted so the specimen can be ignited at the top by a small pilot flame. The percentage of oxygen is adjusted until the level is reached where a specimen will just burn for a 3 minute period or for a length of 50 millimeters. That minimum oxygen concentration is reported as the Oxygen Index (01). The greater the OI value, the more flame retardant the specimen tested. More widely used industrially is the UL 94 vertical burn test. It is a small scale test which measures the ability of a specimen to propagate flame and is used as the basis for a voluntary standard for electrical and electronic devices, cabinets for television receivers, business machines, computers and the like. In the UL 94 vertical burn test, which is conducted in a draft free enclosure, a specimen of the dimensions 0.5 inches in width by 5 inches in length by the minimum use thickness is suspended vertically with its bottom edge 12 inches above a layer of cotton gauze. The bottom edge is contacted with a 3/4 inch flame from a prescribed laboratory burner held 3/8 inch below the bottom edge. Two ten second ignitions are supplied to each of 5 specimens and the UL 94 classification determined based on the following criteria: Classification V-0 V-1 V-2

Maximum total flame time 10 ignitions, sec 50 250 250

Maximum individual flame time, sec 10 30 30

Flaming drips (igniting cotton) None None Allowed

Maximum afterglow time, sec 30 60 60 By this test method, V-0 is the classification for a material showing the greatest flame retardancy and V-2 the classification of one demonstrating the least.

Tensile/Elongation ASTM D638: A type I size dumbell specimen is clamped in an Instron testing machine fitted with appropriate grips and extensometer. A testing speed of 20 inches a minute is set, the machine started and operated until the specimen breaks. Tensile strength and percent elongation are calculated from the appropriate test data. Flexural Properties ASTM D790, Method I. A specimen of the dimensions 0.125 inch in thickness by 1.0 inch in width by 3 inches in length is placed in the flexural fixture of an Instron testing machine, set at a testing speed of 0.05 inch a minute. The machine is started and the stress-strain relationship plotted on a graph. From the graph the maximum fiber stress and tangent modulus of elasticity are calculated.

Izod Impacted, ASTM D256 Method I: A specimen of the dimensions 0.125 inch in thickness by 0.5 inch width by 2.5 inches in length, and notched to prescribed dimensions, is clamped in an appropriate impact tester and the weighted pendulum allowed to swing downward to contact the specimen. Impact strength is then calculated from the energy readout on the dial and specimen thickness.

Heat Deflection Temperature (HPT) ASTM D648: A specimen of the dimensions 0.125 inch in thickness by 0.5 inch width by 5 inches in length, is placed in the appropriate testing apparatus fitted with a weight to apply a force of 264 psi. The surrounding oil is heated at 2°C a minute and the temperature recorded when the specimen has deflected 0.010 inch.

Flow Properties by Spiral Mold Procedure: Plastics compounds were injection molded on a 30-ton Newbury molder fitted with a 3/16 inch wide by 65 inch long cavity spiral mold. A melt temperature - injection pressure combination was selected which yielded a suitable injection cushion for the compound with the anticipated highest melt flow. All compounds were then molded at these machine settings and the length of the resulting spirals noted.

The data obtained for Examples 1-9 are shown in Table II.

Analyses of the experimental results shown in Table II permit the following observations and conclusions:

Example 1 - A control sample containing no invention additive illustrates its intrinsic low flow and absence of significant flame retardancy.

Examples 2 and 3 - These comparative examples containing only brominated polystyrene additives provide good flame retardancy but only at the expense of reduced flow.

Example 4 - This comparative example shows the combined effects of addition of a brominated polystyrene and of a previously known phosphate flow modifier to be good flame retardancy and flow but adversely affected Heat Distortion Temperature (HDT), and Tensile and Flexural Strengths.

Examples 5-9 - These invention examples show the excellent flame retardancy and formulation flow achieved by combined use of brominated polystyrene and tetrabromophthalate esters.

Example 10. This example illustrates the superiority of tetrabromophthalate diesters to aromatic phosphate esters in resisting volatilization when heated at elevated temperatures. "Juicing" of flow modifiers from polyphenylene ether resins and objectionable appearance and stress cracking problems are closely related to volatility of the modifier.

Therefore, in order to determine their relative volatilities, sufficient di-(2-ethylhexyl) tetrabromophthalate and Kronitex 50 were weighed into tared 4-inch diameter Petri dishes to just cover the bottoms of the dishes with thin films. The dishes, with contents, were then heated in a forced draft oven held at 175°C and the weight loss determined hourly over eight hours. In the following table, these weight losses are expressed as the percent of the original weight:

Example 11-15 Compositions of Examples 11-15, prepared by the previously described procedures, are detailed in Table IV. The compounding resin utilized was PREVEX PQA, a polystyrene modified polyphenylene ether copolymer commercially available from Borg- Warner Corporation.

Compositions of Table IV were evaluated by previously described methods, with the results being shown in Table V.

Analyses of the experimental results shown in Table IV permit the following observations and conclusions:

Example 11 - This control sample, containing no invention additives illustrates its intrinsic low flow and absence of significant flame retardancy.

Example 12 - This comparative example, containing only a brominated polystyrene additive, shows excellent flame retardancy but largely unimproved flow.

Example 13 - This comparative example shows the combined effects of addition of a brominated polystyrene and of a previously known phosphate flow modifier to be improved flame retardancy and flow but adversely affected Heat Distortion Temperature and Tensile and Flexural Strengths.

Examples 14 and 15 - These invention examples show the excellent flame retardancy and formulation flow achieved by combined use of brominated polystyrene and tetrabromophthalate esters.

For convenience in user handling, premixed concentrates of plastic additive materials are frequently provided by manufacturers. Such concentrates of polybrominated styrene, tetrabromophthalates, and, optionally, antimony trioxide are considered to fall within the scope of this invention whether supplied as mixtures containing only these two or three materials or further diluted by the addition of MPPE resins. Such concentrates desirably incorporate about 1-20 parts by weight each of the brominated alkenyl aromatic resin and the diester of tetrabromophthalic acid, and, optionally, about 1-15 parts by weight of the enhancing agent as previously disclosed. Advantageously, such concentrates may also be provided in blended form with MPPE resin as a diluent. Compositions of exemplary concentrates are given in Examples 16-18.

Example 16

Constituent Parts by Weight

LMBPS 3.0

DTBP 7.5

Example 17 Constituent Parts by Weight

LMBPS 3.0

DTBP 5.0

Antimony Trioxide 1.0

Example 18

Constituent Parts by Weight

Pyro-Check 68PB 3.0

Di-(n-octyl) tetra- brmophthalate 7.5

Antimony trioxide 1.5

MPPE 10.0

Claims

1. A flame retarded modified polyphenylene ether resin composition comprising: a polyphenylene ether homo- or co-polymer modified with an alkenyl aromatic resin; an effective amount of a brominated alkenyl aromatic resin; an effective amount of a diester of tetrabromophthalic acid; and an effective amount of an enhancing agent.

2. A flame retarded modified polyphenylene ether resin composition, as claimed in claim 1, wherein the composition comprises about 1-20 percent by weight of a brominated alkenyl aromatic resin of the formula:

where R and R prime are H or CH₃; X may be 2 to 5; Y is 1 when R is CH₃ and 0 to 3 when R is H; and n is 5 to 10,000.

3. A flame retarded modified polyphenylene ether resin composition, as claimed in claim 1, wherein the composition comprises about 1-20 percent by weight of a diester of tetrabromophthalic acid of the formula:

where R" and R"' independently represent straight and branched C_4-18 aliphatic groups; C_4-18 alkenyl groups; C_2-6 haloalkenyl groups; benzyl, phenyl, and halo-substituted benzyl and phenyl; and R₂(OCH₂CH(R₃))_x-OH, where R₂ may be CH₃, C₂H₅, and H; R₃ may be CH₃ or H; and X is 1-10.

4. A flame retardant modified polyphenylene ether resin composition, as claimed in Claim 1, wherein the enhancing agent is an oxide or halide of a metal selected from the group consisting of antimony, arsenic, bismuth, boron tin and zinc.

5. A flame retarded modified polyphenylene ether resin composition, as claimed in Claim 1, wherein the brominated alkenyl aromatic resin is brominated polystyrene having a degree of bromination lying in the range of about 2 to 3 and a degree of polymerization lying in the range of about 1-20; wherein the diester of tetrabromophthalic acid is di-(2-ethyl- hexyl) tetrabromophthalate; and wherein the enhancing agent is antimony oxide.

6. A flame retarded modified polyphenylene ether resin composition wherein the polyphenylene ether is a homopolymer of 2 , 6 dimethylphenol alloyed with polystyrene .

7. A flame retarded modified polyphenylene ether resin composition, as claimed in Claim 1, wherein the polyphenylene ether is a copolymer of 2, 6-dimethylphenol and 2,3,6-trimethylphenol alloyed with polystyrene.

8. In a flame retarded modified polyphenylene ether resin composition comprising a polyphenylene ether homo- or co-polymer modified with an alkenyl aromatic resin, a flame retardant agent and an enhancing agent, the improvement comprising the use of a mixture of brominated alkenyl aromatic resin and a diester of tetrabromophthalic acid as the flame retardant agent.

9. An additive concentrate composition for modified polyphenylene ether resins comprising: about 1-20 parts by weight a brominated alkenyl aromatic resin of the formular:

where R and R prime are H or CH₃; X may be 2 to 5; Y is 1 when R is CH₃ and 0 to 3 when R is H; and n is 5 to 10,000; about 1-20 parts by weight of a diester of tetrabromophthalic acid of the formula:

where R" and R"' independently represent straight or branched C_4-18 aliphatic groups; C_4-18 alkenyl groups; C_2-6 haloalkyl groups; benzyl, phenyl, and halo-substituted benzyl and phenyl; and R₂(OCH₂CH(R₃))_xOH, where R₂ may be CH₃, C₂H₅, or H; R₃ may be CH₃ or H; and X is 1 to 10;); and optionally, about 1-15 parts by weight of an enhancing agent selected from the group consisting of an oxide or halide of a metal selected from the group consisting of antimony, arsenic, bismuth, boron tin and zinc.

10. An additive concentrate composition, as claimed in claim 9, and further compressing modified polyphenylene ether resin as a diluent.